The invention relates to an economical method of making a polymer having reduced VOCs and coating compositions containing such polymers. In one embodiment, the method of invention requires providing a reactant mixture (a), providing a solvent mixture (b) comprising a reactive component (c) which is substantially free of any heteroatoms and is not a crystalline solid at room temperature and comprises (i) from 12 to 72 carbon atoms, and (ii) at least two functional groups, and subjecting the reactant mixture (a) in the solvent mixture (b) to polymerization conditions sufficient to polymerize reactant mixture (a) to provide a mixture (d) of a polymer (axe2x80x2) in solvent mixture (b), wherein reactive component (c) under the polymerization conditions is substantially nonreactive: (1) with the components of reactive mixture (a), (2) in the polymerization of reactant mixture (a) and (3) with the polymer (axe2x80x2). Coating compositions of the invention comprising polymers made by the disclosed method provide low VOCs without any reduction in application or performance properties.

The invention relates to the manufacture of thermosetting polymers and/or oligomers for use in curable coating compositions, especially curable coating compositions having a low or reduced VOC.
Curable thermoset coating compositions are widely used in the coatings art. They are often used as topcoats in the automotive and industrial coatings industry. Such topcoats may be basecoats, clearcoats, or mixtures thereof. Color-plus-clear composite coatings are particularly useful as topcoats where exceptional gloss, depth of color, distinctness of image, or special metallic effect is desired. The automotive industry has made extensive use of these coatings for automotive body panels.
Color-plus-clear composite coatings, however, require an extremely high degree of clarity in the clearcoat to achieve the desired visual effect. High-gloss coatings also require a low degree of visual aberrations at the surface of the coating in order to achieve the desired visual effect such as high distinctness of image (DOI). Finally, such composite coatings must also simultaneously provide a desirable balance of finished film properties such as durability, hardness, flexibility, and resistance to environmental etch, scratching, marring, solvents, and/or acids.
In order to obtain the extremely smooth finishes that are generally required in the coatings industry, coating compositions must exhibit good flow before curing. Good flow is observed when the coating composition is fluid enough at some point after it is applied to the substrate and before it cures to a hard film to take on a smooth appearance. Some coating compositions exhibit good flow immediately upon application and others exhibit good flow only after the application of elevated temperatures.
One way to impart fluid characteristics and good flow to a coating composition is to incorporate volatile organic solvents into the composition. These solvents provide the desired fluidity and flow during the coating process, but evaporate upon exposure to elevated curing temperatures, leaving only the coating components behind.
However, the use of such solvents increases the volatile organic content (VOC) of the coating composition. Because of the adverse impact that volatile organic solvents have on the environment, many government regulations impose limitations on the amount of solvent that can be used. Increasing the percentage nonvolatile (% NV) of a coating composition or decreasing the VOC provides a competitive advantage with respect to environmental concerns, air permitting requirements and cost.
Prior art attempts to improve the VOC of polymers and coating compositions have generally focused on the removal of volatile organic solvents from polymers by methods such as vacuum distillation. However, such techniques have significant disadvantages. First, they generally require the use of more energy and labor which leads to higher costs. Increased costs also result from the disposal of removed solvent. Finally, the viscosity of the stripped polymer often creates processing and manufacturing challenges.
There is thus a continuing desire to reduce the volatile organic content (VOC) of coating compositions and the components of such coating compositions while avoiding the problems of the prior art. This must be done without sacrificing the rheological properties of the coating composition required for trouble-free application of the composition while still maintaining the optimum level of smoothness and appearance. Finally, any such coating composition must continue to provide finished films having a good combination of properties with respect to durability, hardness, flexibility, and resistance to chipping, environmental etch, scratching, marring, solvents, and/or acids.
More particularly, it would be very desirable to provide a method of making film-forming components for coating compositions wherein the film-forming component is polymerized in a material which is inert with respect to polymerization but does not volatilize upon exposure to elevated curing temperature. Ideally, such a material would enter into the film-forming reaction of a thermosetting coating composition incorporating said film-forming component. The desired effect of incorporating the material into the final film would be to increase the crosslink density of the coating and to impart positive film attributes such as etch resistance, flexibility, scratch and mar, chip resistance.
Accordingly, it is an object of the instant invention to provide a method of making binders for curable coating compositions which provide all of the advantages of prior art binders, but that contribute lower levels of volatile organic solvents to the final coating composition while still providing desirable application properties as well as finished films having commercially acceptable appearance and performance properties.
It is another object of the invention to provide a method of making acrylic oligomers and/or polymers for curable coating compositions which provide all of the advantages of prior art acrylic oligomers and binders, but that contribute lower levels of volatile organic solvents to the final coating composition while still providing desirable application properties as well as finished films having commercially acceptable appearance and performance properties.
It is another object of the invention to provide a method of making film-forming components for curable coating compositions wherein the film-forming component is polymerized in a material which (1) is inert with respect to polymerization, (2) does not contribute to the VOC of a coating composition incorporating said film-forming component, and (3) enters into the film-forming reaction when the coating composition is cured.
These and other objects have been achieved with the methods and coating compositions of the invention.
In one embodiment, the method of invention requires providing a reactant mixture (a), providing a solvent mixture (b) comprising a reactive component (c) which is substantially free of any heteroatoms and is not a crystalline solid at room temperature and comprises (i) from 12 to 72 carbon atoms, and (ii) at least two functional groups, and subjecting the reactant mixture (a) in the solvent mixture (b) to polymerization conditions sufficient to polymerize reactant mixture (a) to provide a mixture (d) of a polymer (axe2x80x2) in solvent mixture (b), wherein reactive component (c) under the polymerization conditions is substantially nonreactive: (1) with the components of reactive mixture (a), (2) in the polymerization of reactant mixture (a) and (3) with the polymer (axe2x80x2).
In another embodiment of the invention, a method of making an acrylic polymer is provided, comprising providing a reactant mixture (a) comprising one or more ethylenically unsaturated monomers having at least one carbonxe2x80x94carbon double able to undergo free radical polymerization, providing a solvent mixture (b) comprising a reactive component (c) which is substantially free of any heteroatoms and is not a crystalline solid at room temperature and comprises (i) from 12 to 72 carbon atoms, and (ii) at least two functional groups, and subjecting the reactant mixture (a) in the solvent mixture (b) to polymerization conditions sufficient to polymerize reactant mixture (a) to provide a mixture (d) of a polymer (axe2x80x2) in solvent mixture (b), wherein reactive component (c) under the polymerization conditions is substantially nonreactive: (1) with the components of reactive mixture (a), (2) in the polymerization of reactant mixture (a) and (3) with the polymer (axe2x80x2).
The invention also provides curable coating compositions, comprising a mixture (d) comprising a polymer (axe2x80x2) and a solvent mixture (b) and at least one crosslinking agent (e). Mixture (d) is made by the process comprising providing a reactant mixture (a), providing a solvent mixture (b) comprising a reactive component (c) which is substantially free of any heteroatoms and is not a crystalline solid at room temperature and comprises (i) from 12 to 72 carbon atoms, and (ii) at least two functional groups, and subjecting the reactant mixture (a) in the solvent mixture (b) to polymerization conditions sufficient to polymerize reactant mixture (a) to provide a mixture (d) of a polymer (axe2x80x2) in solvent mixture (b), wherein reactive component (c) under the polymerization conditions is substantially nonreactive: (1) with the components of reactive mixture (a), (2) in the polymerization of reactant mixture (a) and (3) with the polymer (axe2x80x2). The at least one crosslinking agent (e) comprises at least one functional group (i) which is reactive with reactive component (c).
Coating compositions of the invention comprising crosslinking agent (e) and mixture (d) of polymer (axe2x80x2) and reactive component (c) made by the disclosed method provide coating compositions having low or reduced VOCs without any reduction in application or performance properties.
The invention provides a method a making a polymer (axe2x80x2), especially a mixture (d) of polymer (axe2x80x2) in a solvent mixture (b) comprising at least one reactive component (c). The mixture (d) of polymer (axe2x80x2) in a solvent mixture (b) is especially suitable for use in coating compositions having low VOCs.
xe2x80x98Low VOC polymer or coating compositionxe2x80x99 as used herein refers to polymers or coating compositions having a VOC of no more than 3.2 lbs. of volatile organic solvent/gallon of polymer or coating composition, more preferably no more than 2.4 lbs. of volatile organic solvent/gallon of polymer or coating composition, and most preferably no more than 1.6 lbs. of volatile organic solvents/gallon of polymer or coating composition.
Polymer (axe2x80x2) is provided in a mixture (d) in combination with a solvent mixture (b). Polymer (axe2x80x2) results from the polymerization of reactant mixture (a) comprising one or more components. Solvent mixture (b) comprises a particular reactive additive or component (c) that must be substantially inert with respect to three things under the polymerization conditions to which reactant mixture (a) is subjected. xe2x80x9cSubstantially inertxe2x80x9d as used herein refers to a degree of reaction between the reactive additive component (c) and the reaction mixture (a) of less than 3% of the total functionality of (c), preferably less than 2%, and most preferably less than 1% of the total functionality of reactive additive (c). In a most preferred embodiment, any reaction between reactive additive (c) and reaction mixture (a) will be attributable solely to the presence of unwanted impurities and/or contaminants in reactive additive (c).
First, the reactive component (c) must be substantially inert or nonreactive with the components of reactant mixture (a) under the polymerization conditions. Thus, reactive component (c) must generally be free of any functional groups which might be reactive with one or more functional groups of the components of reactant mixture (a) under the conditions used to polymerize reactant mixture (a). Functional groups (ii) of reactive component (c) will normally be free of any groups that are reactive with one or more functional groups of the components of reactant mixture (a) under conditions used to polymerize reactant mixture (a).
Second, the reactive component (c) must be substantially inert or nonreactive during the polymerization of reactant mixture (a). That is, reactive component (c) may not polymerize under the polymerization conditions which result in the transformation of reactant mixture (a) into polymer (axe2x80x2).
Finally, the reactive component (c) must be substantially inert or nonreactive with the resulting polymer (axe2x80x2) while under the polymerization conditions used to polymerize reactant mixture (a). For example, if an epoxy functional component and an acid functional component are polymerized to provide an epoxy upgrade polymer, the reactive component (c) may not have any functional groups reactive with the secondary hydroxyl formed by the ring opening of the oxirane functional group.
Put another way, the functional groups (ii) of reactive component (c) are limited to those functional groups which may be on one or more components of reactant mixture (a) but which do not enter into the polymerization of reactant mixture (a) or any graft polymerization processes involving reactant mixture (a) or polymer (axe2x80x2).
Polymer (axe2x80x2) may be any polymer, oligomer or mixture thereof, resulting from the polymerization of reactant mixture (a). As used herein xe2x80x98polymer (axe2x80x2) may generally have a number average molecular weight of from 400 to 50,000 Daltons. Usually, the polymer (axe2x80x2) will have a number average molecular weight of from 1000 to 50,000 Daltons. Polymer (axe2x80x2) may be an acrylic polymer, a polyurethane polymer, a polyester polymer, an epoxy upgrade polymer, a dendrimer polymer, or the like. Polymer (axe2x80x2) will preferably be an acrylic polymer, a polyurethane polymer, or a polyester polymer. Most preferably, polymer (axe2x80x2) will be an acrylic polymer or a polyurethane polymer, with acrylic polymers being especially preferred.
It will be appreciated that the composition of reactant mixture (a) will depend upon the desired type of polymer (axe2x80x2). In general, reactant mixture (a) will be comprised of one or more components, preferably two or more components that can be subjected to polymerization conditions to produce a polymer (axe2x80x2). More preferably the component of reactant mixture (a) will be monomers or compounds that can react with each other and/or compounds produced therefrom, to provide a polymer of increased molecular weight relative to the initial starting reactants of mixture (a).
If polymer (axe2x80x2) is an acrylic polymer, reactant mixture (a) will be comprised of ethylenically unsaturated monomers having at least one carbonxe2x80x94carbon double bond able to undergo free radical polymerization.
Illustrative ethylenically unsaturated monomers include, without limitation, alpha, beta-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms such as acrylic, methacrylic, and crotonic acids, and the esters, nitriles, and amides of those acids; alpha, beta-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms and the anhydrides, monoesters, and diesters of those acids; vinyl esters, vinyl ethers, vinyl ketones, and aromatic or heterocylic aliphatic vinyl compounds. Carbamate functional ethylenically unsaturated monomers, cyclic carbonate functional ethylenically unsaturated monomers, and/or isocyanate functional ethylenically unsaturated monomers may also be used, most preferably in combination with other ethylenically unsaturated monomers.
Representative examples of suitable esters of acrylic methacrylic, and crotonic acids include, without limitation, those esters from reaction with saturated aliphatic and cycloaliphatic alcohols containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, lauryl, stearyl, cycolhexyl, trimethylcyclohexyl, tetrahydrofurfuryl, stearyl, sulfoethyl, and isobornyl acrylates, methacrylates, and crotonates; and polyalkylene glycol acrylates and methacrylates.
Representative examples of other ethylenically unsaturated polymerizable monomers include, without limitation, such compounds as fumaric, maleic, and itaconic anhydrides, monoesters, and diesters with alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and tert-butanol.
Representative examples of polymerizable vinyl monomers include, without limitation, such compounds as vinyl acetate, vinyl propionate, vinyl ethers such as vinyl ethyl ether, vinyl and vinylidene halides, and vinyl ethyl ketone.
Representative examples of aromatic or heterocylic aliphatic vinyl compounds include, without limitation, such compounds as styrene, alpha-methyl styrene, vinyl toluene, tert-butyl styrene, and 2-vinyl pyrrolidone.
Representative examples include acrylic and methacrylic acid amides and aminoalkyl amides; acrylonitrile, and methacrylonitriles.
Other suitable examples include acrylates or methacrylates having hydroxy, epoxy, or other functional groups, such as hydroxyalkyl acrylates and methacrylates, glycidyl esters of methacrylic and acrylic acid such as glycidyl methacrylate, and aminoalkyl esters of methacrylic or acrylic acid like N,N-dimethylaminoethyl (meth)acrylate.
Acrylic monomers having carbamate functionality in the ester portion of the monomer are well known in the art and are described, for example in U.S. Pat. Nos. 3,479,328, 3,674,838, 4,126,747, 4,279,833, and 4,340,497, 5,356,669, and WO 94/10211, the disclosures of which are incorporated herein by reference. One method of synthesis involves reaction of a hydroxy ester with urea to form the carbamyloxy carboxylate (i.e., carbamate-modified acrylic). Another method of synthesis reacts an xcex1,xcex2-unsaturated acid ester with a hydroxy carbamate ester to form the carbamyloxy carboxylate. Yet another technique involves formation of a hydroxyalkyl carbamate by reacting a primary or secondary amine or diamine with a cyclic carbonate such as ethylene carbonate. The hydroxyl group on the hydroxyalkyl carbamate is then esterified by reaction with acrylic or methacrylic acid to form the monomer. Other methods of preparing carbamate-modified acrylic monomers are described in the art, and can be utilized as well. The acrylic monomer can then be polymerized along with other ethylenically unsaturated monomers, if desired, by techniques well known in the art.
Ethylenically unsaturated isocyanate monomers are well-known in the art and include meta-isopropenyl-.alpha.alpha.-dimethylbenzyl isocyanate (sold by American Cyanamid as TMI(copyright)) and isocyanatoethyl methacrylate.
Cyclic carbonate ethylenically unsaturated monomers are well-known in the art and include (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate.
When polymer (axe2x80x2) is an acrylic resin, it will generally have a number average molecular weight of from 1000 to 50,000, preferably from 10,000 to 25,000, with molecular weights of from 15,000 to 20,000 being most preferred.
In a preferred embodiment, polymer (axe2x80x2) will be a hydroxyl or carbamate functional resin which may or may not be water dispersible. For example, in one preferred embodiment, polymer (axe2x80x2) will be a water dispersible acrylic polymer having a hydroxyl equivalent weight of from 250 to 1500 g/mole and an acid equivalent weight of from 500 to 3000 g/mole. In another preferred embodiment, the polymer (axe2x80x2) will be a water dispersible acrylic polymer having a carbamate equivalent weight of from 250 to 1500 g/mole and an acid equivalent weight of from 500 to 3000 g/mole. In another preferred embodiment, the polymer (axe2x80x2) is an acrylic polymer having a hydroxyl equivalent weight of from 250 to 1500 g/mole and an acid equivalent weight greater than 3000 g/mole. Finally, in another preferred embodiment, the polymer (axe2x80x2) is an acrylic polymer having a carbamate equivalent weight of from 250 to 1500 g/mole and an acid equivalent weight greater than 3000 g/mole.
If polymer (axe2x80x2) is a polyester, reactant mixture (a) will be comprised of a mixture of at least one polycarboxylic acid and/or anhydride, and at least one polyol and/or epoxide. Such reactants will be subjected to polymerization via esterification.
The polycarboxylic acids used to prepare the polyester polymer (axe2x80x2) consist primarily of monomeric polycarboxylic acids or anhydrides thereof having 2 to 18 carbon atoms per molecule. Among useful acids are phthalic acid, hexahydrophthalic acid, adipic acid, sebacic acid, maleic acid, and other dicarboxylic acids of various types. Minor amounts of monobasic acids can be included in the reaction mixture, for example, benzoic acid, stearic acid, acetic acid, and oleic acid. Also, higher carboxylic acids can be used, for example, trimellitic acid and tricarballylic acid. Anhydrides of the acids referred to above, where they exist, can be used in place of the acid. Also, lower alkyl esters of the acids can be used, for example, dimethyl glutarate and dimethyl terephthalate.
Polyols that can be used to prepare the polyester polymer (axe2x80x2) include diols such as alkylene glycols. Specific examples include ethylene glycol, 1,6-hexanediol, neopentyl glycol, and 2,2-dimethyl-3-hydroxypropionate. Other suitable glycols include hydrogenated Bisphenol A, cyclohexanediol, cyclohexanedimethanol, caprolactone-based diols such as the reaction product of e-caprolactone and ethylene glycol, hydroxy-alkylated bisphenols, polyether glycols such as poly(oxytetramethylene)glycol, and the like.
Although the polyol component of reactant mixture (a) can comprise all diols, polyols of higher functionality can also be used. It is preferred that the polyol be a mixture of at least one diol; and at least one triol, or one polyol of higher functionality. Examples of polyols of higher functionality would include trimethylol ethane, trimethylol propane, pentaerythritol, and the like. Triols are preferred. The mole ratio of polyols of higher functionality to diol is less than 3.3/1, preferably up to 1.4/1. Limited amounts of monofunctional alcohols, such as ethylhexanol, may also be used.
Polyurethane polymers (axe2x80x2) may be prepared by the polymerization of a reactant mixture (a) comprising at least one di- and/or polyisocyanate and at least one polyol. They are prepared by a chain extension reaction of a polyisocyanate (e.g., hexamethylene diisocyanate, isophorone diisocyanate, MDI, etc.) and a polyol (e.g., 1,6-hexanediol, 1,4-butanediol, neopentyl glycol, trimethylol propane). They can be provided with active hydrogen functional groups by capping the polyurethane chain with an excess of diol, polyamine, amino alcohol, or the like include in reactant mixture (a).
For example, suitable polyisocyanates can be an aliphatic polyisocyanate, including a cycloaliphatic polyisocyanate or an aromatic polyisocyanate. Useful aliphatic polyisocyanates include aliphatic diisocyanates such as ethylene diisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane, 1,6-diisocyanatohexane, 1,4-butylene diisocyanate, lysine diisocyanate, 1,4-methylene bis-(cyclohexyl isocyanate) and isophorone diisocyanate. Useful aromatic diisocyanates and araliphatic diisocyanates include the various isomers of toluene diisocyanate, meta-xylenediisocyanate and para-xylenediisocyanate, also 4-chloro-1,3-phenylene diisocyanate, 1,5-tetrahydro-naphthalene diisocyanate, 4,4xe2x80x2-dibenzyl diisocyanate and 1,2,4-benzene triisocyanate can be used. In addition, the various isomers of xcex1xe2x80x2, xcex1xe2x80x2, xcex1xe2x80x2, xcex1xe2x80x2-tetramethyl xylylene diisocyanate can be used. Also useful as the polyisocyanate are isocyanurates such as DESMODUR(copyright) N 3300 from Mobay and biurets of isocyanates such as DESMODUR(copyright) N100 from Mobay.
Active hydrogen-containing chain extension agents generally contain at least two active hydrogen groups, for example, diols, dithiols, diamines, or compounds having a mixture of hydroxyl, thiol, and amine groups, such as alkanolamines, aminoalkyl mercaptans, and hydroxyalkyl mercaptans, among others. Both primary and secondary amine groups are considered as having one active hydrogen. Active hydrogen-containing chain extension agents also include water. In a preferred embodiment of the invention, a polyol is used as the chain extension agent, to provide a polyurethane. In an especially preferred embodiment, a diol is used as the chain extension agent with little or no higher polyols, to minimize branching. Examples of preferred diols which are used as polyurethane chain extenders include 1,6 hexanediol, cyclohexanedimethylol, and 1,4-butanediol. While polyhydroxy compounds containing at least three hydroxyl groups may be used as chain extenders, the use of these compounds produces branched polyurethane resins. These higher functional polyhydroxy compounds include, for example, trimethylolpropane, trimethylolethane, pentaerythritol, among other compounds.
Monofunctional capping alcohols such as 2-ethylhexanol may also be used. The mono- or polyfunctional alcohol may contain additional functional groups. Non-limiting examples are glycidol, hydroxyalkylcarbamates such as hydroxy ethyl carbamate or hydroxy butyl carbarnate, and hydroxy acids such as 1-hydroxybutylic acid.
The polyurethane polymer may be chain extended in any manner using these compounds having at least two active hydrogen groups. Accordingly, reactant mixture (a) may thus include such compounds with a mixture of polyisocyanate, polyol, and multi-functional compounds.
It is an aspect of the invention that the reactant mixture (a) is polymerized in a solvent mixture (b).
Solvent mixture (b) will comprise a reactive component (c) which is substantially free of any heteroatoms and is not a crystalline solid at room temperature and comprises (i) from 12 to 72 carbon atoms, and (ii) at least two functional groups. The non-functional part of reactive component (c) of the invention will generally have from 12 to 72 carbons, more preferably from 18 to 54 carbons, and most preferably from 36 to 54 carbons. In a particularly preferred embodiment of the invention, the nonfunctional part of reactive component (c) will have 36 carbons.
xe2x80x9cHeteroatomsxe2x80x9d as used herein refers to atoms other than carbon or hydrogen. The phrase xe2x80x9csubstantially withoutxe2x80x9d heteroatoms as used herein means that the portion of reactive component (c) which does not include functional groups (ii) will generally have no more than two atoms which are other than carbon or hydrogen, i.e., atoms such as N, O, Si, mixtures thereof, and the like. More preferably, that portion of reactive component (c) that does not include functional groups (ii) will have no more than one atom that is other than carbon or hydrogen. In a most preferred embodiment, that portion of reactive component (c) that does not include functional groups (ii) will have no heteratoms, i.e., will consist solely of carbon and hydrogen atoms. Thus, in a most preferred aspect of the invention, the only heteratoms in reactive component (c) will be present in functional groups (ii).
It is another aspect of the invention that reactive component (c) will not be a crystalline solid at room temperature, i.e., at temperatures of from 65 to 75xc2x0 F. xe2x80x9cCrystallinexe2x80x9d refers to a solid characterized by a regular, ordered arrangement of particles. Rather, reactive component (c) will be an amorphous solid, a wax or a liquid at room temperature. xe2x80x9cAmorphousxe2x80x9d refers to a noncrystalline solid with no well-defined ordered structure.
In a more preferred embodiment of the invention, reactive component (c) will comprise a mixture of two or more saturated or unsaturated structures selected from the group consisting of noncyclic structures for reactive component (c), aromatic-containing structures for reactive component (c), cyclic-containing structures for reactive component (c), and mixtures thereof. Saturated structures are preferred, especially where durability issues are of concern. For example, a most preferred reactive component (c) will comprise a mixture of two or more structures selected from the group consisting of aliphatic structures for reactive component (c), aromatic-containing structures for reactive component (c), cycloaliphatic-containing structures for reactive component (c), and mixtures thereof.
It is particularly preferred that reactive component (c) comprise at least two, more preferably three, of the three cited structures. If reactive component (c) comprises only two of the three cited structures for reactive component (c), then at least one of the two structures must be present as a mixture of two or more isomers thereof.
For example, the mixture of reactive components (c) may comprise at least one aliphatic structure for reactive component (c) and at least one other structure for reactive component (c) selected from the group consisting of aromatic-containing structures for reactive component (c), cycloaliphatic-containing structures for reactive component (c), and mixtures thereof. If the xe2x80x98at least one other structure for reactive component (c)xe2x80x99 is not a mixture of aromatic-containing structures for reactive component (c) and cycloaliphatic-containing structures for reactive component (c), either the aromatic-containing structures or the cycloaliphatic containing structures must be present as a mixture of two or more isomers.
Alternatively, the mixture of reactive components (c) may comprise at least one aromatic-containing structure for reactive component (c) and at least one other structure for reactive component (c) selected from the group consisting of aliphatic structures for reactive component (c), cycloaliphatic-containing structures for reactive component (c), and mixtures thereof. If the xe2x80x98at least one other structure for reactive component (c)xe2x80x99 is not a mixture of aliphatic structures for reactive component (c) and cycloaliphatic-containing structures for reactive component (c), either the aliphatic structures or the cycloaliphatic containing structures must be present as a mixture of two or more isomers.
In a most preferred embodiment, reactive component (c) will comprise one or more aliphatic structures for reactive component (c), one or more aromatic-containing structures for reactive component (c), and one or more cycloaliphatic-containing structures for reactive component (c). Particularly advantageous mixtures of reactive component (c) will comprise from 3 to 25% by weight of reactive component (c) having an aliphatic structure, from 3 to 25% by weight of reactive component (c) having an aromatic-containing structure, and 50 to 94% by weight of reactive component (c) having a cycloaliphatic-containing structure. More preferred mixtures of reactive component (c) will comprise from 3 to 18% by weight of reactive component (c) having an aliphatic structure, from 5 to 23% by weight of reactive component (c) having an aromatic-containing structure, and 55 to 85% by weight of reactive component (c) having a cycloaliphatic-containing structure. Most preferred mixtures of reactive component (c) will comprise from 5 to 10% by weight of reactive component (c) having an aliphatic structure, from 10 to 20% by weight of reactive component (c) having an aromatic-containing structure, and 60 to 70% by weight of reactive component (c) having a cycloaliphatic-containing structure.
Finally, reactive component (c) must comprise at least two functional groups (ii) per molecule. Preferred reactive components (c) may have from two to six functional groups (ii) while most preferably reactive component (c) will have two to three functional groups (ii).
Functional groups (ii) may be selected from a variety of active hydrogen containing groups and groups reactive with such active hydrogen containing groups. Examples of illustrative functional groups are hydroxy, isocyanate (blocked or unblocked), epoxy, carbamate, aminoplast, aldehyde, acid, epoxy, amine, cyclic carbonate, urea, mixtures thereof, and the like.
In a most preferred embodiment, functional group (ii) will be any one of a pair of reactants that would result in a thermally irreversible chemical linkage. The term xe2x80x9cthermally irreversible linkagexe2x80x9d refers to a linkage the reversal of which is not thermally favored under the traditional cure schedules used for automotive coating compositions. Illustrative examples of suitable thermally irreversible chemical linkages are urethanes, ureas, esters and ethers. Preferred thermally irreversible chemical linkages are urethanes, ureas and esters, with urethane linkages being most preferred. Such chemical linkages will not break and reform during the crosslinking process as is the case with the linkages formed via reaction between hydroxyl groups and aminoplast resins.
It will be appreciated that if one member of a xe2x80x9cpairxe2x80x9d is selected for use as functional group (ii), the other member of the xe2x80x9cpairxe2x80x9d will generally be selected as functional group (ei) of crosslinking agent (e) discussed below. Examples of illustrative reactant xe2x80x9cpairsxe2x80x9d are hydroxy/isocyanate (blocked or unblocked), hydroxy/epoxy, carbamate/aminoplast, carbarnate/aldehyde, acid/epoxy, amine/cyclic carbonate, amine/isocyanate (blocked or unblocked), urea/aminoplast, and the like.
Preferred functional groups (ii) are hydroxyl, primary carbamate, isocyanate, aminoplast functional groups, epoxy, carboxyl and mixtures thereof. Most preferred functional groups (ii) are hydroxyl, primary carbamate, and mixtures thereof, with primary carbamate groups being particularly preferred.
Illustrative examples of suitable reactive components (c) having functional groups (ii) which are carboxyl are fatty acids and addition reaction products thereof, such as dimerized, trimerized and tetramerized fatty acid reaction products and higher oligomers thereof. Suitable acid functional dimers and higher oligomers may be obtained by the addition reaction of C12-18 monofunctional fatty acids. Suitable monofunctional fatty acids may be obtained from Cognis Corporation of Ambler, Pa. Such materials will be acid functional and will contain some unsaturation. In addition, saturated and unsaturated dimerized fatty acids are commercially available from Uniqema of Wilmington, Del.
Hydroxyl functional reactive components (c) are commercially available as the Pripol(trademark) saturated fatty acid dimer (Pripol(trademark) 2033) supplied by Uniqema of Wilmington, Del. Hydroxyl functional reactive components (c) may also be obtained by reduction of the acid group of the above-discussed fatty acids.
Reactive components (c) having two or more carbamate functional groups may be obtained via the reaction of the hydroxyl functional reactive components (c) with a low molecular weight carbamate functional monomer such as methyl carbamate under appropriate reaction conditions. Alternatively, carbamate functional reactive components (c) may be made via decomposition of urea in the presence of hydroxyl functional reactive component (c) as described above. Finally, carbamate functional reactive components (c) can be obtained via the reaction of phosgene with the hydroxyl functional reactive component (c) followed by reaction with ammonia.
Amine groups suitable for use as functional group (ii) may be primary or secondary, but primary amines are most preferred. Reactive components (c) having amine functional groups (ii) may be obtained via reaction of the acid functional component (c) to form an amide, followed by conversion to a nitrile and subsequent reduction to an amine
Reactive components (c) having isocyanate functional groups (ii) may be obtained via reaction of the amine functional component (c) described above with carbon dioxide.
Aminoplast functional groups may be defined as those functional groups resulting from the reaction of an activated amine group and an aldehyde or formaldehyde. Illustrative activated amine groups are melamine, benzoguanamine, amides, carbamates, and the like. The resulting reaction product may be used directly as functional group (ii) or may be etherified with a monofunctional alcohol prior to use as functional group (ii).
Reactive components (c) having aminoplast functional groups (ii) may be made via reaction of carbamate functional reactive component (c) as described above with formaldehyde or aldehyde. The resulting reaction product may optionally be etherified with low boiling point alcohols.
Reactive components (c) having aldehyde functional groups (ii) may be made via reduction of the acid functional reactive components (c) described above.
Reactive components (c) having urea functional groups (ii) may be made via reaction of an amine functional component (c) with urea. Alternatively, amine functional component (c) can be reacted with phosgene followed by reaction with ammonia to produce the desired urea functional groups (ii).
Reactive components (c) having epoxy functional groups (ii) may be made using either saturated or unsaturated fatty acids described above. If an unsaturated fatty acid is used, reaction with peroxide will form internal epoxy groups. More preferably, an acid or hydroxyl functional reactive component (c) will be reacted with epichlorohydrin. Preferred epoxy functional reactive components (c) will be obtained using saturated starting materials.
Reactive components (c) having cyclic carbonate functional groups (ii) may be made via carbon dioxide insertion into an epoxy functional reactive component (c) as described above.
A preferred example of for reactive component (c) will have the following structures therein:
As discussed above, it is an aspect of the invention that reactive component (c) under the polymerization conditions is substantially nonreactive: (1) with the components of reactive mixture (a), (2) in the polymerization of reactant mixture (a) and (3) with the polymer (axe2x80x2). Thus, the functional groups (ii) of reactive component (c) discussed above must be selected so as not to participate in the polymerization reaction of reactant mixture (a). The functional groups (ii) must also not react with any of the functional groups of the components reactant mixture (a) and/or on polymer (axe2x80x2).
In general, if one of the reactants present in mixture (a) contains a functional group which is a member of a reactant pair discussed above with respect to functional groups (ii) and functional group (ei), reactive additive (c) may not contain the other member of the xe2x80x9cpairxe2x80x9d.
For example, when reactive component (c) is used in a free radical acrylic polymerization where an isocyanate functional monomer is used, the functional groups (ii) of reactive component (c) may not be hydroxy or amine. When high polymerization temperatures are used (such as 140xc2x0 C.), functional groups (ii) of reactive component (c) may not be acid functional. When reactive component (c) is used in an ionic radical polymerization, the level of non-aromatic unsaturated groups on reactive component (c) must be minimized, preferably to a level of less than 5 weight percent, more preferably less than 2 weight percent, based on the total weight of reactive component (c).
When the reactive component (c) is used in a urethane polymerization, functional groups (ii) must not contain any groups that would react with the isocyanate or active proton source (usually hydroxy). The typical functional groups on reactive component (c) that should be avoided in this case are hydroxy and amine groups. Other functional groups on reactive component (c) might also have to be avoided depending on the nature of any functional groups on the active hydrogen material. For example, if glycidol is used as a capping group in the urethane polymerization, the reactive component (c) must be free of acid groups.
When the reactive component (c) is used in a polyester polymerization, functional groups (ii) may not groups that will react with anhydrides, acids, and alcohols. Examples of such groups to be avoided include acids, hydroxy, epoxy, unblocked isocyanates and the like. In such as case, non-limiting examples of functional groups (ii) of reactive component (c) would be carbamate, vinyl or mixtures thereof.
Finally, it is within the scope of the invention that reactive component (c) may have functional groups that are also reactive with polymer (axe2x80x2) when exposed to cure conditions, but are inert during polymerization conditions. A non-limiting example of this would be use of a ketamine functionalized reactive component (c) with an epoxy, cyclic carbonate and/or isocyanate functional acrylic polymer.
In addition to reactive additive (c), solvent mixture (b) may further comprise other solvents and/or cosolvents such as water and/or organic solvents. Illustrative solvents include aromatic hydrocarbons, such as, petroleum naphtha or xylenes, ketones such as methyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone or acetone; esters such as butyl acetate or hexyl acetate; and glycol ether esters, such as propylene glycol monomethyl ether acetate. Other examples of useful solvents include, without limitation, m-amyl acetate, ethylene glycol butyl ether-acetate, xylene, N-methylpyrrolidone, blends of aromatic hydrocarbons, and mixtures of these.
In general, solvent mixture (b) will comprise from 0 to 95% by weight of reactive additive (c), more preferably from 0 to 75% by weight, and most preferably from 0 to 20% by weight, all based on the total weight of solvent mixture (b).
Coating compositions of the invention will comprise mixture (d) made by the method of the invention wherein mixture (d) comprises polymer (axe2x80x2) and solvent mixture (b). Coating compositions of the invention may further comprise other known film-forming binders not made by the method of the invention, but most preferably will not. Illustrative examples include acrylic polymers, polyurethane polymers, polyester polymers, epoxy functional polymers, mixtures thereof, and the like.
In general, coating compositions of the invention will comprise mixture (d) having from 10 to 90% by weight nonvolatile of polymer (axe2x80x2), more preferably from 20 to 80% by weight nonvolatile of polymer (axe2x80x2) and most preferably from 40 to 60% by weight nonvolatile of polymer (axe2x80x2), based on the total weight of mixture (d).
For the coating compositions of the invention, solvent mixture (b) will generally have from 5 to 100% by weight of reactive additive (c), more preferably from 30 to 100% by weight of reactive additive (c), and most preferably from 80 to 100% by weight of reactive additive (c), all based on the total weight of solvent mixture (b).
Coating compositions of the invention will also comprise at least one crosslinking agent (e). Crosslinking agent (e) will comprise at least one functional group (ei) that is reactive with reactive component (c). Crosslinking agent (e) may further comprise additional functional groups (eii) that are reactive with the functional groups of polymer (axe2x80x2). Alternatively, the coating compositions of the invention may further comprise an additional crosslinking agent (f) comprising functional groups reactive with polymer (axe2x80x2). In a preferred embodiment, the coating compositions of the invention will comprise at least one crosslinking agent (e) having both functional groups (ei) and (eii).
Illustrative examples of at least one crosslinking agent (e) are those crosslinking agents having one or more crosslinkable functional groups. Such groups include, for example, aminoplast, hydroxy, isocyanate, amine, epoxy, acrylate, vinyl, silane, and acetoacetate groups. These groups may be masked or blocked in such a way so that they are unblocked and available for the cross-linking reaction under the desired curing conditions, generally elevated temperatures. Useful crosslinkable functional groups include hydroxy, epoxy, acid, anhydride, silane, activated methylene and acetoacetate groups. Preferred crosslinking agents will have crosslinkable functional groups that include hydroxy functional groups and amino functional groups and isocyanate groups. Di- and/or polyisocyanates and/or aminoplast resins are most preferred for use as crosslinking agents in coating compositions comprising the mixture (dxe2x80x2) of the invention. Mixed crosslinkers may also be used.
For example, when the reactive additive (c) comprises hydroxy functional groups, for example, the crosslinking agent may be an aminoplast resin, a polyisocyanate and blocked polyisocyanate resin (including an isocyanurate, biuret, or the reaction product of a diisocyanate and a polyol having less than twenty carbon atoms), and an acid or anhydride functional crosslinking agent.
In a more preferred embodiment, the crosslinker (e) will have functional groups (ei), that will react with the functional group on (c) to form a crosslink that is non-reversible under cure conditions. This will help to insure that the reactive additive remains crosslinked in the film. Some non-limiting examples of crosslinkable functional groups pairs that fall under this category are: carbamate:aminoplast, hydroxy:epoxy, acid:epoxy, vinyl:vinyl, and hydroxy:isocyanate. An example of a crosslink that is reversible under cure conditions is hydroxy:aminoplast, and hydroxy:activated methylene.
The coating compositions of the invention are particularly suitable for use in automotive coating compositions, especially primers, basecoats, and/or clearcoats, with clearcoats being especially preferred. The coating compositions of the invention may be powder coatings, waterborne, power slurry, or solventborne.
Coating compositions of the present invention preferably form the outermost layer or layer of coating on a coated substrate. Preferably, the instant coating compositions are applied over one or more layers of primer coatings. For example, the coating compositions of the invention may be used as an automotive topcoat coating applied over a layer of electrocoat primer and/or primer surfacer.
When such coating compositions are used as topcoat coatings, they preferably have a 20 degree gloss, as defined by ASTM D523-89, of at least 80 or a DOI, as defined by ASTM E430-91, of at least 80, or both. Such gloss and DOI are particularly useful in providing an automotive finish that will appeal to the buyer of the vehicle. Topcoat coatings may be one coat pigmented coatings or may be a color-plus-clear composite coating.
Coating compositions of the present invention, if used as a one coat pigmented coating or the color coating of a color-plus-clear composite coating, will include one or more pigments well-known in the art, such as inorganic pigments like titanium dioxide, carbon black, and iron oxide pigments, or organic pigments like azo reds, quinacridones, perylenes, copper phthalocyanines, carbazole violet, monoarylide and diarylide yellows, naphthol orange, and the like.
In a preferred embodiment, the coating composition of the present invention is the clearcoat of a color-plus-clear composite coating. The clearcoat may be applied over a color coat according to the invention or may be applied over a color coat of a formulation already known in the art. Pigmented color coat or basecoat compositions for such composite coatings are well known in the art and do not require explanation in detail herein. Polymers known in the art to be useful in basecoat compositions include acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds, and polysiloxanes. Such basecoats may comprise the polymer (axe2x80x2) of the invention. Preferred polymers include acrylics and polyurethanes.
Other materials well-known to the coatings artisan, for example, surfactants, fillers, stabilizers, wetting agents, dispersing agents, adhesion promoters, UV absorbers, light stabilizers such as HALS, antioxidants, solvents, catalysts, and/or rheology control agents, may also be incorporated into the coating compositions of the invention. The amount of these materials used must be controlled to achieve the desired performance properties and/or to avoid adversely affecting the coating characteristics.
Coating compositions can be coated onto an article by any of a number of techniques well known in the art. These include, for example, spray coating, dip coating, roll coating, curtain coating, and the like. For automotive body panels, spray coating is preferred. When the coatings will be relatively thick, they are usually applied in two or more coats separated by a time sufficient to allow some of the water and/or solvent evaporate from the applied coating layer (xe2x80x9cflashxe2x80x9d). The coats as applied are usually from 1 to 3 mils of the coating composition, and a sufficient number of coats are applied to yield the desired final coating thickness.
Where a color-plus-clear composite coating is applied to the prepared substrate, the color coat is usually applied in one or two coats, then allowed to flash, and the clear coat is then applied to the uncured color coat in one or two coats. The two coating layers are then cured simultaneously. Preferably, the cured base coat layer is 0.5 to 1.5 mils thick and the cured clear coat layer is 1 to 3 mils, more preferably 1.6 to 2.2 mils thick.
Coating compositions of the invention are preferably subjected to conditions so as to cure the coating layers. Although various methods of curing may be used, thermal-curing is preferred. Generally, thermal curing is effected by exposing the coated article to elevated temperatures provided primarily by radiative heat sources. Curing temperatures will vary depending on the particular blocking groups used in the crosslinking agents, however they generally range between 93 degree C. and 177 degree C. In a preferred embodiment, the cure temperature is between 135 degree C. and 165 degree C. In another preferred embodiment, a blocked acid catalyst is included in the composition and the cure temperature is between 115 dgree C. and 140 degree C. In a different preferred embodiment, an unblocked acid catalyst is included in the composition and the cure temperature is between 80 degree C. and 100 degree C. The curing time will vary depending on the particular components used and physical parameters, such as the thickness of the layers. Typical curing times range from 15 to 60 minutes, and preferably 15-25 minutes at the target temperature.

Method for obtaining coating compositions having reduced VOC


A combustion-engined setting tool for driving fastening elements in constructional components includes a member (32) arranged in the combustion chamber (13) for generating turbulence of an oxidant-fuel mixture filling the combustion chamber (13), an ignition unit (23) for igniting the oxidant-fuel mixture, a drive for at least temporarily driving the turbulence generating member (32), and a switch (22) for actuating the ignition unit (23) and actuated by the turbulence generating member (32).

1. Field of the Invention
The present invention relates to a combustion-engined setting tool for driving fastening elements such as, e.g., nails, bolts, pins, in a constructional components and which includes a combustion chamber, means arranged in the combustion chamber for generating turbulence of an oxidant-fuel mixture filling the combustion chamber, an ignition unit for igniting the oxidant-fuel mixture, and drive means for a least temporarily driving the turbulence generating means.
2. Description of the Prior Art
In the setting tools described above, a portion of the liquid gas or another vaporable fuel, which is mixed with an oxidant, e.g., environmental air, is combusted in the tool combustion chamber. In order to obtain as high as possible drive-in energy from the combustion process, it is important that the combustion of the gas or gas mixture takes place under turbulent flow conditions. Only a turbulent combustion permits to obtain a necessary drive-in energy from the combustion process, producing a sufficiently rapid pressure increase in the combustion chamber for accelerating the setting piston to a degree necessary for driving a fastening element in. With a laminar combustion, the combustion process and the resulting pressure increase take place so slow that only a fraction of the required mechanical energy can be obtained from the combustion process.
European Patent EP-0 544471B1 discloses a combustion-engined setting tool having a combustion chamber for combusting a mixture of air and fuel gas and in which ventilator means is provided in the combustion chamber for generating turbulence therein. The ventilator means is driven by an electric motor which is supplied with electrical energy from a battery. The ventilator means is actuated by the head switch of the setting tool when the setting tool is pressed against a constructional component. The ignition unit is actuated for igniting the air-fuel mixture in the combustion chamber when an actuation switch is actuated, while the head switch is still closed.
The drawback of the setting tool of the European Patent consist in complicated and costly electronics which actuates and controls the ventilator means and which also actuates ignition. A further drawback consists in that several accumulators are needed, which increases the tool weight.
German Publication DE 199 62 711 A1 discloses a combustion-engined setting tool in which a separation plate with through-openings is arranged in the combustion chamber, dividing the combustion chamber in two chambers. An adjustment device is used for changing the distance between the separation plate and a rear wall that axially limits the combustion chamber, whereby the volumes of the forechamber and the main chamber change. In the forechamber, a first portion of the air-fuel mixture is ignited, with the flame jets penetrating into the main chamber through the openings in the separation plate, creating turbulence in the main chamber and igniting the air-fuel mixture therein.
The drawback of the tool disclosed in DE 199 62 711 A1 consists in that the combustion process is sensible to the environmental conditions such as, e.g., temperature, scavenging ratio of the combustion chamber, or the environmental pressure. This results from the fact that the turbulence is generated as a result of the combustion process itself, i.e., when the combustion in the forechamber is poor, then the combustion in the main chamber is even worse.
German Publication DE 102 26 878 A1 discloses a combustion-engined setting tool in which, as in the previously described case, the turbulence is generated by a perforated separation plate that remains static before and during the ignition process. After the combustion process ends, the separation plate and the rear wall are displaced in a direction toward the piston guide, so that the combustion chamber completely collapses. After the combustion chamber has collapsed, another, non-perforated plate is displaced as a result of application thereto a spring-biasing force from a location at the rear end of the setting tool remote from the piston guide up to the rear wall in order to scavenge the space before this plate with fresh air.
Here, likewise, the drawback consists in that the combustion process is sensible to the fluctuation of the environmental conditions such as, e.g., temperature, scavenging ratio of the combustion chamber, or the environmental pressure.
The object of the present invention is to provide a setting tool of the type described above and in which the drawbacks of the known tools are eliminated.
Another object of the present invention is to provide a setting tool of the type described above which would have a high energy efficiency.


As described herein, lactosylceramide (LacCer) levels are up-regulated in the CNS during chronic experimental autoimmune encephalomyelitis (EAE), an experimental model of multiple sclerosis (MS). LacCer acts in an autocrine manner to trigger transcriptional programs that promote the recruitment and activation of CNS infiltrating monocytes and microglia, and neurodegeneration. In addition, increased B4GALT6 expression and LacCer levels were detected in CNS MS lesions in human patients. Finally, the inhibition of LacCer synthesis suppressed local CNS innate immunity and neurodegeneration in EAE, and interfered with the activation of human astrocytes in vitro. Thus, B4GALT6 is a therapeutic target for MS and other neuroinflammatory disorders.

Astrocytes are the most abundant cells in the central nervous system (CNS). Under normal conditions astrocytes modulate synaptic activity, and provide nutrients and support needed for neuronal survival1-4. In the context of neuroinflammation, astrocytes control CNS infiltration by peripheral pro-inflammatory leukocytes5-8 and regulate the activity of microglia, oligodendrocytes and cells of the adaptive immune system9. Thus, it is important to characterize the mechanisms regulating astrocyte activation during CNS inflammation, as well as potential targets for the therapeutic modulation of astrocyte activity.
Multiple sclerosis (MS) is a chronic demyelinating autoimmune disease of the CNS. In most patients, MS initially presents a relapsing-remitting clinical course (relapsing-remitting MS, RRMS) that is followed by a progressive phase (secondary progressive MS, SPMS) characterized by a continued and irreversible accumulation of disability in which available treatments show limited efficacy10. Recent findings suggest that the local CNS innate immune response drives disease progression in SPMS9,11,12.


A wireless transmission system includes a first wireless transmission device and a second wireless transmission device. The first wireless transmission device sets multiplex data to at least one predetermined bit contained in an input first packet and thereby generates a second packet containing the multiplex data, and transmits the second packet to the second wireless transmission device. The second wireless transmission device receives the second packet from the first wireless transmission device, performs error detection on the second packet, and when the error detection ends normally, extracts the multiplex data from the at least one predetermined bit in the second packet.

An approach to achieve high capacity is needed to deal with the recent rapid increase in traffic, and a technique to increase the transmission capacity has been studied (e.g., International Patent Publication No. WO2018/179922).
To increase the transmission capacity, it is necessary to change the operating frequency of a wireless transmission device or increase the bandwidth of a wireless channel for transmitting data. However, in the case of changing the operating frequency or increasing the bandwidth of a wireless channel, it is not possible to easily increase the transmission capacity due to a limitation to device performance and a legal limitation such as a radio law.

Wireless transmission system, wireless transmission device, wireless transmission method, and wireless transmission program


The various laser architectures described herein provide increased gain of optical energy as well as compensation of optical phase distortions in a thin disk gain medium. An optical amplifier presented herein provides for scalable high energy extraction and gains based on a number of passes of the signal beam through a gain medium. Multiple, spatially separate, optical paths may also be passed through the same gain region to provide gain clearing by splitting off a small percentage of an output pulse and sending it back through the amplifier along a slightly different path. By clearing out the residual gain, uniform signal amplitudes can be obtained.

In recent years, there have been significant advances in laser technology including solid state laser technology. This technology is being used in numerous applications including scientific research, manufacturing, medicine, security, communications, and many others. Many laser applications require reliable high power outputs and numerous mechanisms have been developed to achieve such. Indeed, high power laser amplifiers have been developed in a variety of forms to accommodate a wide variety of applications, but each amplifier generally functions to amplify the power of an input pulse or beam to provide an amplified output pulse or beam.
Design of laser amplifiers may be limited by factors related to optical component tolerances in the amplifier to pulses of high-energy laser light and average power loading. For example, in one large class of amplifier designs, known as regenerative amplifiers, multiple passes through a single gain medium or plural gain media are used for efficient extraction of gain. In these regenerative amplifiers, an optical path is defined around which an input pulse makes a number of passes before being coupled out as an amplified pulse.
Regenerative amplifiers are generally used to provide relatively strong amplification of laser pulses. Multiple passes through the gain medium are achieved by placing the gain medium in an optical resonator, together with an optical switch that may be formed by an electro-optic modulator and one or more polarizers. The number of round trips in the resonator is controlled with the optical switch and, when this number is large, a high overall amplification factor (i.e., gain) can be achieved.
While these regenerative amplifiers provide significant gain, they are often difficult to implement due to their complex cavities. Moreover, switching of the laser pulses within the cavity usually decreases the achievable pulse energies or beam due to nonlinear propagation effects within the switch. Additionally, regenerative amplifiers, under some operating conditions, suffer from chaotic or multi-stable operation. In these operating conditions, the residual gain in the gain medium after energy extraction significantly affects the gain that can be imparted on a subsequent signal pulse. Regenerative amplifiers also generally amplify one pulse at a time. Therefore, the repetition rate of the laser system is less than the reciprocal of the time between the injection and ejection of each amplified pulse.
Another concern in high power laser systems regards heat. High average power laser systems typically produce heat and most laser architectures are designed with this in mind because high temperatures within a gain medium can reduce gain and/or cause thermo-mechanical strains that result in stress-induced birefringence. Temperature distributions in a gain medium can also lead to phase distortions which result in poor laser beam quality. At more extreme temperatures, damage to the gain material or optical coatings can occur. High temperatures within a laser system can also lead to mechanical movements that result in optical misalignment.
In order to efficiently extract heat from a solid gain medium, the fraction of cooled surface area per heated volume is generally maximized. Two geometries that have been used for high power laser systems include fibers and thin disks. In the case of fibers, two dimensions are minimized and one dimension is maximized so that a large surface area to volume ratio can be obtained for efficient cooling. Additionally, fiber amplifier geometries support very large gain-length products. Fiber amplifiers, however, are not optimal for high-power short pulses because high intensities may result from transmission of laser pulse energy through a very small cross section of an optical fiber. For high pulse powers and small cross-sections, the peak intensity can be extremely high and lead to deleterious nonlinear propagation effects.
One solution for thermal management of pulsed laser operation includes using disk shaped gain media, in which only one dimension is minimized. This geometry also provides large surface areas for heat extraction per gain volume. The thin disk is typically cooled from one side and is accessed optically from the other. A reflective surface is provided between the cooling system and the gain medium. Alternatively, the disk may be cooled from both sides if a thermally conductive medium is used that can also transmit the laser pump and signal beams of energy. Generally, the signal beam is the desired beam of laser energy that is operated on and/or used in a particular application whereas the pump beam may include any type of energy operable to stimulate the gain medium and amplify the signal beam.
Though the thin disk geometry can be efficiently cooled, the pump absorption-length product and signal gain-length product for typical gain media is small. For this reason, thin disk based lasers generally use a multi-pass optical system for optical pumping, and a multi-pass system for the signal beam. After each pass of the pump beam, a portion of the pump beam is absorbed. However, after multiple passes of the pump beam, most of the pump laser light can be absorbed by the crystal. For example, small gains may be achieved each time the signal traverses through a thin disk. Higher amplitude gains thus require multiple traversals of the signal beam through the thin disk so that a larger effective gain-length product can be achieved. Because greater energy extraction can be achieved by using a larger gain volume, a thin disk may utilize a relatively large pump and signal beam spot size. This allows for higher power without exceeding intensity thresholds for deleterious nonlinear propagation effects.
Although heat can be removed from a thin disk, thermal gradients typically lead to phase distortions due to temperature dependent indices of refraction, thermal expansion, and/or strain effects. For thin disk geometries where a reflective surface is included, thermo-mechanical distortions can lead to especially strong phase distortions and each pass of the signal beam can lead to accumulated phase distortions. These phase distortions can also include birefringent effects, such as strain-induced birefringence.
Accumulated phase distortions in a laser system can also lead to "hot spots" or losses that limit the laser powers that can be achieved. For example, if a thin disk imparts focusing phase distortions to a signal beam, the beam may eventually be focused to such a small spot size that it could damage an optical component with extreme intensities or even ionize the air, losing energy in the process. Accordingly, the laser power would be intentionally "dialed down" to avoid these effects. A signal beam that accumulates a divergence with traversals of the disk can also become too large for an optic, aperture, or an amplified region for a subsequent traversal through the gain medium. Consequently, divergence also results in an energy loss that limits the laser power.
In high power diode pumped laser systems, laser energy from multiple laser diodes may be collected and transmitted to a gain region via fiber. However, such generally requires beam combining mechanisms where multiple diode sources can be independently transmitted to the gain region. This allows for higher pump powers to be used than could be obtained from a single diode source. Additionally, multimode fibers may be used to supply higher average power. In any case, fibers are limited in the amount of power that they can easily transmit. A laser system that provides for simplified beam combining from multiple sources, at the gain medium, would provide a significant benefit.


A surgical retractor includes a side loading socket configured to receive a connector head. A linearly moveable slide retains the connector head within the socket cavity. The slide has a convex face outwardly from the socket cavity which assists in xe2x80x9csnappingxe2x80x9d in a connector head. A convex inner face assists in retaining an inserted connector head. A notch in the tip of the slide assists in preventing rotation of a connector head having opposing locking pins when one of the pins is received in a recess at the back of the socket cavity. A grip is connected to the slide which may move the slide from a locked to a released position within a slot in the socket body.

The present invention relates generally to a surgical retractor apparatus used with interchangeable retractor blades. More particular the present invention relates to a surgical retractor with side loading interchangeable retractor blades.
When conducting some surgical procedures, it is often desirable to retract tissue. Although there are a number of procedures and devices available to retract tissue, U.S. Pat. No. 6,042,540 allows for the top loading as well as the side loading of retractor blades into a socket. The side loading feature of this, and other prior art, is believed to be advantageous whereby the surgeon""s vision is not obscured while connecting, or disconnecting a blade from a retractor. The ""540 patent discloses a number of retractors which can utilize the blade of FIG. 1A, specifically, the longitudinal retractor of FIG. 3, the transverse retractor of FIG. 4, and the side-loading hand-held retractor of FIG. 5. As shown in FIGS. 1A and 1C, the blades typically have connector heads locking pins typically extend from opposite sides of the longitudinal axis of the connector head. Although the ""540 patent specifically shows a top loading connector head, other connector heads also employ the opposing locking pin construction.
The ""540 patent utilizes a xe2x80x9ccam memberxe2x80x9d to restrain a connector head within a socket cavity. There are believed to be a number of problems with this design. First, cams are known in the art typically as: xe2x80x9ca disc or cylinder having an irregular form such that its motion, usually rotary gives to a part or parts in contact with it a specific rocking or reciprocating motion or motionsxe2x80x9d. In the ""540 patent, the rotation of the cam 130 about pivot 128 locks and unlocks the connector head from within the socket chamber. One of the perceived drawbacks of this xe2x80x9ccamxe2x80x9d design is the release lever 124 rotates and extends away from the socket 12 as the cam is moved in and out of the socket chamber.
Another perceived problem with the design shown and described in the ""540 patent is the cam is described as being positioned at least partially xe2x80x9cwithinxe2x80x9d a side loading socket. While this design appears to allow for the grip of the socket to tighten if a blade were to be attempted to be pulled side-ways out of the socket cavity, this tightening effect also would appear to cause an inserted connector head to bind instead of rotate within the socket cavity.
Accordingly, a need exists for an improved retractor design.
A need exists for a surgical retractor which accepts blades having a connector head at least in a side loading manner.
Another need exists for a surgical retractor which securely retains connector heads in a socket.
Another need exists for a side loading surgical retractor socket which does not rely on an awkward cam mechanism.
Yet another need exists for a side loading surgical retractor socket which allows a connector head to xe2x80x9csnapxe2x80x9d in to a locked configuration without a need for an operator to manually operate a locking mechanism.
Accordingly, a surgical retractor includes a body having a socket for receiving a connector head. The socket has a slide which moves linearly toward and away from a connector head when positioned within the socket. A convex surface on a first face of the slide allows for the connector head to be pushed into position or xe2x80x9csnappedxe2x80x9d in, while a convex surface on a second face of the slide is believed to assist in retaining an inserted connector head in position within the socket. The second face of the socket may also be constructed with a notch at a tip of the slide which allows pinned hubs to be received within the notch to resist turning in at least one direction. While the preferred embodiments accepts only side loaded connector heads, other non-preferred embodiments could accept top loaded connector heads as well.


An image forming apparatus includes an image bearing member, a transfer member disposed facing the image bearing member to form a transfer region therebetween, a transfer bias application device to apply to the transfer region a transfer bias including a direct current (DC) component and an alternating current (AC) component to transfer the toner image onto the recording medium as the recording medium passes through the transfer region, and a controller operatively connected to the transfer bias application device to allow, during a bias change period in a sheet absent period in which the image bearing member rotates and no recording medium passes through the transfer region, the transfer bias application device to selectively apply to the transfer region one of the transfer bias without the AC component and the transfer bias with a peak-to-peak voltage of the AC component less than that applied in image formation.

1. Field of the Invention
Exemplary aspects of the present invention generally relate to an image forming apparatus, such as a copier, a facsimile machine, a printer, or a multi-functional system including a combination thereof.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile capabilities, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges a surface of an image bearing member (which may, for example, be a photoconductive drum); an optical writer projects a light beam onto the charged surface of the image bearing member to form an electrostatic latent image on the image bearing member according to the image data; a developing device supplies toner to the electrostatic latent image formed on the image bearing member to render the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image bearing member onto a recording medium or is indirectly transferred from the image bearing member onto a recording medium via an intermediate transfer member; a cleaning device then cleans the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the unfixed toner image to fix the unfixed toner image on the recording medium, thus forming the image on the recording medium.
In known electrophotographic image forming apparatuses, toner images of yellow, magenta, cyan, and black are formed on photosensitive drums of the respective colors. The image forming apparatus using an intermediate transfer method employs a belt-type intermediate transfer member (hereinafter refers to simply as intermediate transfer belt) formed into an endless loop that contacts the photosensitive drums, forming a primary transfer nip therebetween. In the primary transfer nip, a toner image formed on the photosensitive drum is transferred primarily onto the intermediate transfer belt. This process is known as a "primary transfer process".
A secondary transfer roller contacts a peripheral surface of the intermediate transfer belt, forming a secondary transfer nip therebetween, so that the toner image on the intermediate transfer belt is secondarily transferred onto a recording medium in a process known as "secondary transfer process". A secondary transfer opposed roller is disposed inside the loop formed by the intermediate transfer belt, facing the secondary transfer roller with the intermediate transfer belt interposed therebetween. The secondary transfer opposed roller disposed inside the loop of the intermediate transfer belt is grounded. By contrast, the secondary transfer roller disposed outside the loop is supplied with a secondary transfer bias. With this configuration, a secondary transfer electric field causing the toner image to move electrostatically from the secondary transfer opposed roller side to secondary transfer roller side is formed. The toner image on the intermediate transfer belt is transferred secondarily onto a recording medium fed to the secondary transfer nip in appropriate timing such that the recording medium is aligned with the toner image formed on the intermediate transfer belt.
When using a recording medium having a coarse surface such as Japanese paper, a pattern of light and dark according to the surface condition of the recording medium appears in an output image. More specifically, toner does not transfer well to such embossed surfaces, in particular recessed portions of the surface. This inadequate transfer of the toner appears as a pattern of light and dark patches in the resulting output image.
In view of the above, in a known image forming apparatus, instead of using a secondary transfer bias composed only of a direct current (DC) voltage, a bias in which an alternating current (AC) voltage is superimposed on a DC voltage is supplied as a secondary transfer bias, thereby preventing the pattern of light and dark. Such a secondary transfer bias causes the toner to move back and forth between the recessed portions of the recording medium and the image bearing member such as the intermediate transfer belt. Accordingly, the toner contacts the recessed portions of the recording medium, preventing improper transfer of toner. In this configuration, generation of a pattern of light and dark patches is suppressed, as compared with using the secondary transfer bias including the DC voltage only.
The superimposed bias in which the AC component is superimposed on the DC component is used as a transfer bias not only to prevent generation of the pattern of light and dark.
For example, in another known image forming apparatus, the transfer bias including the AC component superimposed on the DC component is used during double sided printing to prevent unevenness of transfer, dropouts of toner, and improper transfer of toner to a non-image formation area of a recording medium. In this configuration, a peak-to-peak voltage of the AC component is equal to or less than twice the absolute value of the DC component.
In another example, the superimposed bias including the AC component superimposed on the DC voltage is used together with an intermediate transfer member with a fluorocarbon resin surface to prevent generation of blank spots in an output image, which often happens in the intermediate transfer method. In this configuration, the peak-to-peak voltage of the AC component is equal to or greater than 2.05 times the DC component.
The superimposed bias is used also to prevent a partial toner transfer failure in character images or line images. In this case, the frequency of the AC component is equal to or less than 4 kHz and the number of cycles is 20 cycles or more.
Although advantageous and generally effective for its intended purpose, there is a drawback of using the superimposed bias with the AC component superimposed on the DC component in that the superimposed bias promotes degradation of parts such as the transfer member and shortens the life of these parts, which is not the case with the transfer bias using the DC component only.
When applying the secondary transfer bias including the superimposed bias having the peak-to-peak voltage of the AC component substantially greater than the absolute value of the DC component, for example, four times greater than the absolute value of the DC component, the toner can be transferred adequately to the recessed portions of the recording medium having a rough surface, and hence a desired image density can be obtained. The pattern of light and dark patches is prevented from appearing on the output image. Although advantageous, because the peak-to-peak voltage of the AC component of the secondary transfer bias is significantly higher, for example, four times greater than the absolute value of the DC component, the AC component promotes degradation of the transfer member.
In view of the above, there is demand for an image forming apparatus that is capable of preventing degradation of parts even when the transfer bias includes the AC component superimposed on the DC component.

Image forming apparatus and transfer bias application device therein


A radiation image read-out apparatus comprises a main scanning system which scans a stimulable phosphor sheet, on which a radiation image has been stored, with stimulating rays in a main scanning direction. The stimulating rays cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. A sub-scanning system moves the stimulable phosphor sheet with respect to the stimulating rays in a direction approximately normal to the main scanning direction. A light guide member, which has a light input face extending along a main scanning line on the stimulable phosphor sheet, guides the emitted light entering the light guide member at its light input face to a light output face. A photodetector is connected to the light output face. A stimulating ray antireflection film is overlaid on the light input face, and further, may be overlaid over any provided reflection mirror. The stimulating ray antireflection film is designed so that the reflectivity of the stimulating rays from the stimulating ray antireflection film is lowest when the stimulating rays impinge thereupon at an angle of incidence which falls within the range of 30.degree. to 50.degree..

1. Field of the Invention
This invention relates to an apparatus for reading out a radiation image which has been stored on a stimulable phosphor sheet. This invention particularly relates to a radiation image read-out apparatus with which light emitted by a stimulable phosphor sheet in proportion to the amount of energy stored thereon during its exposure to radiation can be detected accurately.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the amount of energy stored during exposure to the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318, 4,387,428, and Japanese Unexamined Pat. Publication No. 56(1981)-11395, it has been proposed to use stimulable phosphors in radiation image recording and reproducing systems. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet) is first exposed to radiation which has passed through an object such as the human body in order to store a radiation image of the object thereon, and is then scanned with stimulating rays, such as a laser beam, which cause it to emit light in proportion to the amount of energy stored during exposure to the radiation. The light, which is emitted by the stimulable phosphor sheet when it is stimulated, is photoelectrically detected and converted into an electric image signal. The image signal is then used to reproduce the radiation image of the object as a visible image on a recording material such as photographic film, on a display device such as a cathode ray tube (CRT), or the like.
FIG. 4 is a perspective view showing a conventional radiation image read-out apparatus. It has been proposed to use radiation image read-out apparatuses like that shown in FIG. 4 in the radiation image recording and reproducing systems described above. With such a radiation image read-out apparatus, a stimulable phosphor sheet, on which a radiation image has been stored, can be scanned with stimulating rays, such as a laser beam, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, and the emitted light can be photoelectrically detected.
In the radiation image read-out apparatus of FIG. 4, stimulating rays 2 are produced by a stimulating ray source 1, and the beam diameter of the stimulating rays 2 is precisely adjusted by a beam expander 3. Thereafter, stimulating rays 2 are deflected by a light deflector 4, which may be constituted of a galvanometer mirror or the like. The deflected stimulating rays 2 are reflected by a plane reflection mirror 5, after which they impinge upon a stimulable phosphor sheet 10 and scan it in the main scanning directions indicated by the double headed arrow A. An f.theta. lens 6 is located in the optical path of the deflected stimulating rays 2 between the light deflector 4 and the plane reflection mirror 5. The f.theta. lens 6 keeps the beam diameter of the stimulating rays 2 uniform, and stimulating rays 2 having a uniform beam diameter scan the stimulable phosphor sheet 10 at a constant speed in the main scanning directions. In the illustrated radiation image read-out apparatus, the stimulating ray source 1, the beam expander 3, the light deflector 4, the plane reflection mirror 5, and the f.theta. lens 6 constitute a main scanning means. While the stimulating rays 2 impinge upon the stimulable phosphor sheet 10, the stimulable phosphor sheet 10 is moved by a sub-scanning means, which may be constituted of an endless belt device 20, in the sub-scanning direction indicated by the arrow B, which direction is approximately normal to the main scanning directions. Consequently, the whole surface of the stimulable phosphor sheet 10 is exposed to the stimulating rays 2. When it is being exposed to the stimulating rays 2, the stimulable phosphor sheet 10 emits light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light enters a light guide member 8. The light guide member 8 has a linear light input face 8a which is positioned along a main scanning line 2c on the stimulable phosphor sheet 10. A ring-shaped light output face 8b of the light guide member 8 is connected to a light receiving face of a photodetector 9, which may be constituted of a photomultiplier. The light guide member 8 is made from a transparent thermoplastic resin sheet, such as an acrylic resin sheet, so that light which has entered the light guide member 8 at its light input face 8a is guided through repeated total reflection inside of the light guide member 8 to the light output face 8b. The light, which has been emitted by the stimulable phosphor sheet 10 and which has entered the light guide member 8, is guided inside of the light guide member 8, emanates from the light output face 8b, and is detected by the photodetector 9. Shapes and materials which are suitable for the light guide member 8 are disclosed in, for example, U.S. Pat. No. 4,346,295.
A filter (not shown) is positioned so that it is in close contact with the light receiving face of the photodetector 9. The filter transmits only light whose wavelengths fall within the wavelength distribution range of the light emitted by the stimulable phosphor sheet 10, and filters out light whose wavelengths fall within the wavelength distribution range of the stimulating rays 2. Therefore, only light which is emitted by the stimulable phosphor sheet 10 will be detected by the photodetector 9. The photodetector 9 converts the light emitted by the stimulable phosphor sheet 10 into an electric signal and feeds it into an image processing circuit 11 which processes the electric signal. The processed electric signal is fed into an image reproducing apparatus, which may be constituted of a CRT, a light beam scanning recording apparatus, or the like, and is used to reproduce a visible image. Alternatively, the processed electric signal may be stored on a magnetic tape or the like.
Also, in the radiation image read-out apparatus described above, in order to improve the efficiency with which the light emitted by the stimulable phosphor sheet 10, when it is scanned with the stimulating rays 2, is guided, a reflection mirror 14 is often located facing the light input face 8a of the light guide member 8 with the main scanning line 2c intervening therebetween. The reflection mirror 14 reflects the light which is emitted from the position on the stimulable phosphor sheet 10 which is being scanned. The light advances from the side opposite to the light guide member 8 towards the light input face 8a of the light guide member 8.
FIG. 5 is a schematic side view showing a major part of the radiation image read-out apparatus shown in FIG. 4. As illustrated in FIG. 5, in the conventional radiation image read-out apparatus described above, a part 2a of the stimulating rays 2 impinging upon a position on the stimulable phosphor sheet 10, which position is being scanned at any given instant, is reflected by the surface of the stimulable phosphor sheet 10. These reflected stimulating rays 2a are then reflected by the light input face 8a of the light guide member 8 and impinge upon a position on the stimulable phosphor sheet 10 which is not being scanned at the given instant, which causes said position on the stimulable phosphor sheet which is not being scanned to emit light. (This phenomenon is referred to as the flare phenomenon.) When the flare phenomenon occurs, light emitted from the position on the stimulable phosphor sheet 10, which position is not being scanned at the given instant, enters the light guide member 8 and is detected by the photodetector 9 together with the light which is emitted from the position on the stimulable phosphor sheet 10, which position is being scanned at the given instant. Therefore, the radiation image stored on the stimulable phosphor sheet 10 cannot be read out accurately, and the contrast in a visible radiation image which is reproduced from the image signal thus detected will be low.
Also, in cases where the reflection mirror 14 is located as illustrated in FIG. 5, parts 2a2a of the stimulating rays 2, which have been reflected from the position on the stimulable phosphor sheet 10, which position is being scanned at the given instant, toward a reflection surface 14a of the reflection mirror 14, are reflected by the reflection surface 14a towards the light input face 8a of the light guide member 8. The reflected stimulating rays 2a2a are even further reflected by the light input face 8aand impinge upon positions on the stimulable phosphor sheet 10, which positions are not being scanned at the given instant. Therefore, when the reflection mirror 14 is provided, an even larger adverse effect occurs from the flare phenomenon, even though the efficiency, with which the light emitted by the stimulable phosphor sheet 10 is guided, is improved.
In order to reduce the adverse effects of the flare phenomenon, the applicant has proposed various radiation image read-out apparatuses.
For example, in U.S. Pat. No. 4,818,880, a radiation image read-out apparatus is disclosed wherein an antireflection film is overlaid on a light input face of the light guide member in order to prevent stimulating rays from being reflected by the light input face. Stimulating rays reflected from a stimulable phosphor sheet are allowed to enter the light guide member and are filtered out by a filter, which is positioned between a light output face of the light guide member and a light receiving face of a photodetector. Also, U.S. Pat. No. 4,680,473 discloses a radiation image read-out apparatus wherein an antireflection film, which will prevent stimulating rays from being reflected by a reflection mirror, is overlaid on a reflection surface of the reflection mirror.
In the disclosed radiation image read-out apparatuses wherein an antireflection film is overlaid on a light input face of a light guide member or on a reflection surface of a reflection mirror, the antireflection characteristics of the antireflection film vary in accordance with the angle of incidence of the stimulating rays, which have been reflected from a stimulable phosphor sheet, upon the antireflection film. It has heretofore been considered to be important that stimulating rays, which have been reflected from a stimulable phosphor sheet and which impinge at a comparatively small angle of incidence upon the light input face of the light guide member or upon the reflection surface of the reflection mirror, be prevented as much as possible from being reflected by the light input face or the reflection surface. Therefore, the antireflection film has heretofore been designed so that its reflectivity is lowest for the reflected stimulating rays, which impinge at an angle of incidence of 0.degree. upon the antireflection film. However, it has recently been revealed that stimulating rays, which are reflected from a position on a stimulable phosphor sheet and impinge at a large angle of incidence upon the light input face of the light guide member or upon the reflection surface of the reflection mirror, have an even greater adverse effect upon the image quality of an image, which is reproduced from an image signal detected from the stimulable phosphor sheet, than those stimulating rays, which are reflected from the stimulable phosphor sheet and impinge at a comparatively small angle of incidence upon the light input face of the light guide member or upon the reflection surface of the reflection mirror. Specifically, stimulating rays, which have been reflected from a position on a stimulable phosphor sheet, which is being scanned at any given instant, and impinge at a large angle of incidence upon the light input face of the light guide member, are reflected by the light input face of the light guide member, and impinge upon and stimulate positions on the stimulable phosphor sheet, which are spaced far apart from the position on the stimulable phosphor sheet which is being scanned at the given instant. Also, stimulating rays, which have been reflected from the position on the stimulable phosphor sheet, which is being scanned at any given instant, and impinge at a large angle of incidence upon the reflection surface of the reflection mirror, are reflected by the reflection surface of the reflection mirror to the light input face of the light guide member, are then reflected by the light input face of the light guide member, and impinge upon and stimulate positions on the stimulable phosphor sheet, which are spaced far apart from the position on the stimulable phosphor sheet which is being scanned at the given instant. For example, if the stimulating rays thus reflected from the light input face of the light guide member stimulate positions on the stimulable phosphor sheet, which are spaced far apart from the position on the stimulable phosphor sheet which position is being scanned at any given instant, the change in image density will not be sharp at regions of the image where it should be sharp, or black lines will appear along directions in which the flare phenomenon has occurred. Therefore, the conventional antireflection film cannot substantially eliminate the problem of stimulating rays being reflected from a stimulable phosphor sheet and impinging at a large angle of incidence upon the light input face of the light guide member or upon the reflection surface of the reflection mirror.


A multimedia device (100) including a separating entity configured to separate a multimedia stream into audio frames and video frames, a sequencing entity configured to add a sequence number to at least one audio frame, a transceiver configured to transmit audio frames to a remote audio device, a controller coupled to a video player, the controller configured to determine a delay associated with transmitting the audio frames to the remote audio device based upon the sequence number and to control the presentation of the video frames at the video player based on the delay.

Currently, many Bluetooth enabled mobile phones support a suite of basic functionality such as the Headset/Hands-Free profiles for enabling hands-free calling, certain OBEX functionality for pushing, pulling, and transferring files, and some type of serial connection for generic access. Most of these phones also support to some degree media content such as MP3 and other format audio clips. Some Bluetooth enabled phones also have the capability to play MP4 type media content, which combines video, audio, and metadata in the same file. However, audio and video synchronization problems may occur when video content is viewed on a cell phone display or other host device and the accompanying audio content is played on a wireless headset. For example, streaming stereo quality audio from a media device like a cell phone or personal computer via Bluetooth to a stereo headset requires the use of the Generic Audio Video Access Profile (GAVDP), Advanced Audio Distribution Profile (A2DP), and the Audio Video Distribution Transport Protocol (ADVTP). A2DP requires use of a sub-band coding (SBC) scheme to ensure interoperability between all Bluetooth devices. If music files are stored on a phone in MP3 format, they generally are transcoded to SBC in order to stream the audio using A2DP. The transcoding of the audio content and the transmission thereof to the wireless headset introduces latency that affects synchronization. Synchronization may also be affected by the re-transmission of data between the host device and the headset and by the subsequent processing of the audio content on the headset.
The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description thereof with the accompanying drawings described below. The drawings may have been simplified for clarity and are not necessarily drawn to scale.

Synchronizing remote audio with fixed video