Aqueous solutions or dispersions of copolymers A) a process of making them and their use in binder compositions. Copolymers A) containing a hydroxy-functional, hydrophobic copolymer I) containing 30 to 85% by weight of (meth)acrylic acid esters having C1 to C18 hydrocarbon radicals in the alcohol portion, aromatic vinyl compounds and/or vinyl esters and 5 to 45% by weight of hydroxy-functional monomers; a hydroxy- and carboxy-functional, hydrophilic-hydrophobic copolymer II) containing 4 to 20% by weight of (meth)acrylic acid esters having C1 to C18 hydrocarbon radicals in the alcohol portion, aromatic vinyl compounds and/or vinyl esters, 4 to 15% by weight of hydroxy-functional monomers and 0.8 to 3.0% by weight of acid-functional monomers; and optionally a hydroxy-functional hydrophobic copolymer III) containing 0 to 16% by weight of hydroxy- and/or non-functional (meth)acrylic acid esters or aromatic vinyl compounds, wherein 1) the sum of Ia), Ib), IIa), IIb) IIc) and IIIa) is 100%, based on the weight of these components, 2) copolymers A) have an acid number, based on solids, of 10 to 28 mg KOH/g substance, 3) the weight percent of monomers IIc) in monomer II) is less than 25% by weight and 4) the weight percent of hydroxy-functional monomers IIb) in copolymer II) is higher than the weight percent of hydroxy-functional monomers Ib) in copolymer I).

1. Field of the Invention
The present invention relates to aqueous copolymer dispersions, which can be cured by various crosslinking resins, to a method of producing these dispersions and to their use in binders.
2. Description of the Prior Art
It is known from a various publications that dispersions based on copolymers can be used in water-thinnable lacquers and coating compositions. For example, EP-A-225,612 and DE-A-3,543,361 describe physically drying polymer dispersions which are produced by a two-stage polymerization process, wherein monomers containing carboxyl groups are used in only one of the two polymerization stages.
So that coatings produced from these dispersions exhibit good resistance to water, ammonia is used in the production thereof. Additions of other neutralizing agents impair the water resistance of coatings and films prepared therefrom. Monomers containing hydroxyl groups are not used, since they can have an unfavorable effect on the resistance to water.
Methods of producing multi-layer coatings are described, e.g., in EP-A-363,723, DE-A-4,009,858, DE-A-4,009,931, EP-A-521,919, DE-A-4,009,932 and EP-A-365,775. A base coat is first applied from which a polymer film is formed. A top coat is then applied and the base coat is then applied and the base coat and top coat are subsequently stoved together. Copolymer dispersions which are produced by a two-stage production process, optionally in combination with aminoplast resins, may be used for the base coat or top coat. Higher coating thicknesses and good visual properties of the films can be obtained by the use of these special copolymer dispersions. A disadvantage of all these dispersions, however, is the high proportion of carboxyl-functional monomers in the hydrophilic copolymer constituent.
JP-A-80/82 166 describes polyacrylate dispersions which are produced by a two-stage process. Starting materials containing carboxyl groups are used in both stages of their production. This results in dispersions with relatively low solids contents. The resulting coatings exhibit a reduced resistance to water.
U.S. Pat. No. 4,151,143 describes polyacrylate dispersions which are produced by a two-stage process, wherein the first stage is produced in organic solution, is subsequently dispersed, and an emulsion polymerization is effected as the second stage in the presence of the first stage. The resulting products have high molecular weights, but exhibit unsatisfactory film formation when used in coating compositions, and overall exhibit properties which differ from those of customary secondary dispersions.
EP-A-557,844 describes aqueous two-component polyurethane coatings which are stabilized by the addition of external emulsifiers and which are based on hydrophilic polyisocyanates and emulsion copolymers which are practically free from carboxylate groups. Due to the high molecular weights of the polymers and the permanent hydrophilic properties of the emulsifiers added, these coating compositions are still deficient with regard to their resistance to water, pigment wetting and film appearance for some applications.
EP-A-358,975 describes aqueous two-component polyurethane compositions which exhibit good properties. For some applications, however, an improvement in their solids content, resistance to water, processing time or reliability of application is needed.
DE-A 4,439,669, DE-A 4,322,242 and JP-A 04001254 describe aqueous two-component polyurethane compositions which are based on copolymers containing special monomers and can be produced by a two-stage process. These special monomers are claimed to impart improved properties to coatings produced therefrom, but result in products which are considerably more costly so that the possibilities of using them economically are limited.
From the multitude of patent applications in the field of polymer dispersions, it is apparent that there is a continuing need for improved products in order to satisfy the increasing demands being made on lacquers or coatings. In particular, dispersions are required which are capable, due to reactive groups, of being cured by suitable crosslinking agents at low temperatures, preferably at room temperature, to form high-quality coatings.
Dispersions which are advantageous from an economic and application technology point of view are those which have a high solids content and excellent stability on storage, both as a dispersion and in a lacquer. A very good capacity for pigmentation, for example, is necessary for systems such as these, and this has a considerable effect on the excellent film appearance which is required. The lacquer films must exhibit very good resistance to solvents, water and environmental effects.
It is an object of the present invention to provide aqueous dispersions that can be used in as many application areas as possible and that exhibit good compatibility with as many commercially available crosslinking agents as possible. It is an additional object to provide a simple and economical production method for the dispersions, i.e., a production method which does not involve a costly, time-consuming distillation stage and which does not involve the use of further components that have to be produced separately. It is another object of the present invention to provide dispersions that have solvent contents of less than 12% and can obtain the desired properties when prepared from raw materials which are readily available and which are as inexpensive as possible.
Surprisingly, these objects may be achieved with the specially selected copolymers of the present invention and the process for their production which are described hereinafter.
The present invention relates to aqueous solutions or dispersions of copolymers A) containing
I) a hydroxy-functional, hydrophobic copolymer containing
Ia) 30 to 85% by weight of (meth)acrylic acid esters having C1 to C18 hydrocarbon radicals in the alcohol portion, aromatic vinyl compounds and/or vinyl esters and
Ib) 5 to 45% by weight of hydroxy-functional monomers,
II) a hydroxy- and carboxy-functional, hydrophilic-hydrophobic copolymer containing
IIa) 4 to 20% by weight of (meth)acrylic acid esters having C1 to C18 hydrocarbon radicals in the alcohol portion, aromatic vinyl compounds and/or vinyl esters,
IIb) 4 to 15% by weight of hydroxy-functional monomers and
IIc) 0.8 to 3.0% by weight of acid-functional monomers, and
III) optionally a hydroxy-functional hydrophobic copolymer containing
IIIa) 0 to 16% by weight of hydroxy- and/or non-functional (meth)acrylic acid esters or aromatic vinyl compounds,
wherein
i) the preceding percentages are based on the total weight of components I), II) and III,
ii) the sum of Ia), Ib), IIa), IIb) IIc) and IIIa) is 100%, based on the weight of these components,
iii) copolymer A) has an acid number, based on solids, of 10 to 28 mg KOH/g substance,
iv) the weight percent of monomers IIc) in monomer II) is less than 25% by weight and
v) the weight percent of hydroxy-functional monomers IIb) in copolymer II) is higher than the weight percent of hydroxy-functional monomers Ib) in copolymer I).
The present invention also relates to a method of preparing aqueous dispersions or solutions of copolymers A) by
a) free radically copolymerizing in a 70 to 95% organic solution a mixture of 30 to 85% by weight of monomers Ia) and 5 to 45% by weight of monomers Ib) to form a hydrophobic, hydroxy-functional copolymer I) which is essentially free from carboxyl groups,
b) subsequently free radically copolymerizing 4 to 20% by weight of monomers IIa), 4 to 15% by weight of monomers IIb) and 0.8 to 3.0% by weight of monomers IIc) to form a hydrophilic-hydrophobic, hydroxy- and carboxy-functional copolymer II)
c) optionally subsequently free radically copolymerizing 0 to 16% by weight of monomers IIIa) to form a hydroxy-functional, hydrophobic copolymer III),
d) neutralizing 70 to 130% of the carboxyl groups and
e) dissolving or dispersing the copolymer A) in water,
wherein the percentages of the monomers are selected such that copolymer A) contains 60 to 90% by weight of copolymer I) and 10 to 40% by weight of copolymer II).
Finally, the present invention relates to binder compositions containing 50 to 90% by weight of copolymers A) and 5 to 50% by weight of at least one crosslinking resin selected from aminoplast resins, blocked polyisocyanates and polyisocyanates containing free isocyanate groups, and to the use of these binders for preparing chemically crosslinked lacquers and coatings.
Preferred are copolymers A) wherein
i) the weight percent of monomers IIa) in copolymer II) is 25 to 65% by weight,
ii) the weight percent of monomers IIb) in copolymer II) is 25 to 65% by weight,
iii) the weight percent of copolymer I) in copolymer mixture A) is 60 to 90% by weight, more preferably greater than 80 to 90% by weight,
iv) the weight percent of copolymer II) in copolymer mixture A) is 10 to 40% by weight, more preferably 10 to less than 20% by weight and
v) at least 70%, preferably at least 90%, of the carboxyl groups in copolymer A) are present in salt form.
More preferably, the weight percent of carboxyl-functional monomers IIc) in copolymer II) is 6 to 18% by weight and results in an acid number of 15 to 20 mg KOH/g substance. In addition, it is preferred that an excess of the neutralizing agent is present such that after converting all of the carboxyl groups into salt form, a pH of 7.9 to 10.0 is obtained.
Particularly preferred copolymers A) are those wherein copolymer I) contains
Ia) 40 to 80% by weight of (meth)acrylic acid esters having C1 to C18 aliphatic hydrocarbon radicals in the alcohol portion and/or aromatic vinyl compounds,
Ib) 7.5 to 35% by weight of hydroxy-functional (meth)acrylic acid esters,
copolymer II) contains
IIa) 4 to 10% by weight of (meth)acrylic acid esters having g of C1 to C18 aliphatic hydrocarbon radicals in the alcohol portion and/or aromatic vinyl compounds,
IIb) 6 to 12% by weight of hydroxy-functional (meth)acrylic acid esters,
IIc) 1.5 to less than 2.5% by weight of acid-functional monomers, and
copolymer III) contains
IIIa) 0 to 16% by weight of hydroxy- and non-functional (meth)acrylic acid esters or aromatic vinyl compounds,
wherein the carboxyl-functional monomers are used in amounts such that copolymer A) has an acid number, based on solids, of greater than 12 to less than 25 mg KOH/g substance results, and wherein greater than 90% of the carboxyl groups exist in salt form.
In another preferred embodiment copolymers A) contain an amount of less than 12% by weight of a solvent mixture of 30 to 95% by weight of a hydrophobic, water-immiscible, unsaponifiable solvent i) and 5 to 70% by weight of a water-miscible or water-soluble, unsaponifiable solvent ii).
It was surprising that the objectives of the present invention could be obtained without the presence of the hydroxy-functional polyethers which are described and employed in EP-A-758,007. The omission of these polyethers considerably simplifies the production of the dispersion according to the invention.
The fact these polyethers are not required is even more surprising when it is considered that copolymers A) are preferably prepared in a special solvent mixture containing 30 to 95% by weight, more preferably 50 to 85% by weight, of a hydrophobic, water-immiscible, unsaponifiable solvents i) and 5 to 70% by weight, more preferably 15 to 50% by weight, of water-miscible or water-soluble, unsaponifiable solvents ii).
Examples of hydrophobic, water-immiscible, unsaponifiable solvents i) include xylene, toluene, solvent naphtha and commercial hydrocarbon mixtures, such as Isopar solvent, Terapin solvent, crystal oil and white spirits. Examples of water-miscible or water-soluble, unsaponifiable solvents include butyl glycol, methoxy-propanol, butyl diglycol, diethylene glycol, dipropylene glycol, ethyl glycol, propyl glycol and methyl diglycol. The preparation of copolymers A) is preferably carried out in the absence of water, i.e., in organic solvents only.
It could not be predicted that it would be possible to prepare copolymers A) in this manner since DE-A-3,022,824, which describes water-thinnable copolymers, states that water-immiscible solvents impair the water-thinnability of the binder compositions. Therefore, this reference teaches away from the addition of these solvents. This is confirmed by the fact that none of the examples use any of the solvents i) described above.
Copolymers A) are prepared by initially copolymerizing monomers Ia) and Ib) to form a copolymer I), wherein the amount of copolymer I) in copolymer dispersion A) is 60 to 90, preferably greater than 80 to 90% by weight, and the proportion of copolymer II) in copolymer dispersion A) is 10 to 40, preferably 10 to less than 20% by weight.
Carboxyl-functional monomers are not used for the production of copolymer I). In order to achieve the objectives of the present invention, it is essential that hydrophobic copolymer I) is initially produced, that hydrophilic-hydrophobic copolymer II) is subsequently produced in situ, and that hydrophobic copolymer III) is optionally produced subsequently in situ.
Other procedures, e.g., initially producing a hydrophilic copolymer and then a hydrophobic copolymer, or producing portions of copolymers I) and II) alternately, or separately producing copolymers I) and II) and then mixing them, result in dispersions of poorer quality.
(Meth)acrylic acid esters Ia) are selected from those having linear or branched aliphatic hydrocarbon radicals with 1 to 18, preferably 1 to 8 carbon atoms. Examples of suitable monomers Ia) include ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, styrene, vinyltoluene, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, xcex1-methylstyrene, and mixtures of these and other monomers. Vinyl esters can optionally be used in combination with these (meth)acrylic acid esters. The amount of monomers Ia) in copolymer A) is 30 to 85, preferably 40 to 80% by weight. Preferred monomers Ia) are styrene, methyl methacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl-acrylate and mixtures of these monomers.
Examples of suitable hydroxy-functional monomers Ib) include hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate and hydroxybutyl methacrylate. The amount of monomers Ib) in copolymer A) is 5 to 45, preferably 7.5 to 35% by weight. Preferred monomers Ib) are hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.
Production of copolymer I) is carried out by a radical-initiated copolymerization of monomer mixture Ia) and Ib) in organic solution, preferably in the previously described solvent mixture. Suitable initiators include organic peroxides, such as di-tert.-butyl peroxide or tert.-butyl peroxy-2-ethylhexanoate, and azo compounds. The initiators are used in amounts of 0.5 to 6.5, preferably 2.0 to 4.5% by weight. The copolymerization is generally conducted at 90 to 180xc2x0 C. as a monomer addition process.
Following the copolymerization of monomers Ia) and Ib) to form copolymer I), copolymerization of monomers IIa), IIb) and IIc) to form copolymer II) is carried out in the presence of copolymer I).
Suitable hydrophobic monomers IIa) are the monomers described under Ia). Preferred monomers IIa) are methyl methacrylate, butyl acrylate, styrene, butyl methacrylate, 2-ethylhexyl acrylate and mixtures of these monomers.
The amount of monomers IIa) in copolymer A) is 4 to 20, preferably 4 to 10% by weight. The amount of hydrophobic monomers IIa) in copolymer II) is 25 to 65, preferably 30 to 60% by weight.
Suitable monomers and preferred monomers IIb) are the monomers described under Ib). The amount of monomers Ib) in copolymer A) is 4 to 15, preferably 6 to 12% by weight. The amount of hydroxy-functional monomers IIb) in copolymer II) is 25 to 65, preferably 35 to 55% by weight, provided that the amount of hydroxy-functional monomers IIb) in copolymer II) must be higher than the amount of hydroxy-functional monomers Ib) in copolymer I). The amount (% by weight) of hydroxy-functional monomers IIb) in copolymer II) is preferably at least 25% higher, more preferably at least 50% higher, than the amount of hydroxy-functional monomers Ib) in copolymer I).
It has surprisingly been found that this increased proportion of crosslinking sites in copolymer II) results, even when there is a low content of hydroxyl groups, in advantageous properties of the resulting coatings, e.g., water and solvent resistance. This has a favorable economic effect on the binder compositions.
Examples of suitable monomers IIc) include acrylic acid, methacrylic acid, maleic acid (anhydride) and other carboxyl-functional copolymerizable monomers. Acrylic acid or methacrylic acid are preferred. The amount of monomers IIc) is 0.8 to 3.0, preferably 1.5 to less than 2.5% by weight. The amount of monomers IIc) in copolymer II) is less than 25, preferably 6 to 18% by weight, so that copolymer II) has a pronounced hydrophilic-hydrophobic character.
When a solvent mixture is used which contains at least one hydrophilic solvent that is not saponifiable and at least one hydrophobic, water-immiscible solvent which is not saponifiable, and when a degree of neutralization is used which is at least 70, preferably greater than 90%, this selected mixture of hydrophobic monomers, hydroxy-functional monomers, and hydrophilic carboxy-functional monomers in copolymer II) results in an excellent level of properties in the resulting coating.
The hydroxyl-functional monomers are used in amounts such that the theoretical hydroxyl number (OH no.), which can be calculated from the equation given below, of copolymer A), based on solids, is greater than 25 to less than 250, preferably greater than 50 to less than 175 mg KOH/g substance:       OH              xe2x80x83                  no      .        =                              amount                                xe2x80x83                              of                                xe2x80x83                              hydroxyl                                xe2x80x83                              monomer                                xe2x80x83                              in                                xe2x80x83                              1000                                xe2x80x83                              g                                xe2x80x83                              of                                xe2x80x83                              A                )            xc3x97      56.1              molecular                    xe2x80x83                  weight                    xe2x80x83                  of                    xe2x80x83                  hydroxyl                    xe2x80x83                  monomer
The carboxyl-functional monomers are used in amounts such that the resulting theoretical acid number (acid no.), which can be calculated from the equation given below, of copolymer A), based on solids, is greater than 8 to less than 33, preferably greater than 12 to less than 25 and more preferably greater than 15 to less than 20 mg KOH/g substance:       acid              xe2x80x83                  no      .        =                              amount                                xe2x80x83                              of                                xe2x80x83                              carboxyl                                xe2x80x83                              monomer                                xe2x80x83                              in                                xe2x80x83                              1000                                xe2x80x83                              g                                xe2x80x83                              of                                xe2x80x83                              A                )            xc3x97      56.1              molecular                    xe2x80x83                  weight                    xe2x80x83                  of                    xe2x80x83                  carboxyl                    xe2x80x83                  monomer
Following the in situ production of copolymer II), copolymerization of monomers IIIa) to form copolymer III) is optionally carried out in the presence of copolymers II) and I). The amount of copolymer III) in copolymer A) is less than 16% by weight, preferably 1 to 13% by weight.
Suitable hydrophobic monomers IIIa) include those described under Ia) and Ib), wherein a mixture of non-functional and hydroxy-functional monomers is preferred.
Organic amines or water-soluble inorganic bases can be used for the neutralization of the carboxyl groups which are incorporated into copolymer II). N-methylmorpholine, triethylamine, dimethylethanolamine, dimethylisopropanol-amine and methyl-diethanol-amine are preferred. Diethylethanolamine, butanolamine, morpholine, 2-aminomethyl-2-methyl-propanol and isophoronediamine are also suitable. Ammonia is less suitable, but can be used in combination with another neutralizing agent.
The neutralizing agent is added in amounts such that 70 to 130%, preferably more than 90% of the carboxyl groups are neutralized. The amount of neutralizing agent is preferably sufficient such that free neutralizing agent is still present after all of the carboxyl groups have been converted into salt form. This corresponds to a degree of neutralization of greater than 100%, which significantly improves, the stability of the dispersion, lacquer stability, pigment wetting and the visual properties of the resulting coatings.
The pH of the aqueous dispersion is 6.0 to 11.0, preferably 7.9 to 10.0. The solids content is greater than 35, preferably xe2x89xa740%.
The organic solvents are used in amounts such that the finished dispersion contains less than 12, preferably less than 9% by weight of solvent. At least a portion of the solvents may also be removed by distillation if particularly low contents of organic solvents are required.
Aqueous copolymers A) are used in or as lacquers or coating compositions in combination with crosslinking resins and optionally with pigments and other known additives from lacquer chemistry. Other binders or dispersions, e.g., those based on polyesters, polyurethanes, polyethers, polyepoxides or polyacrylates, may also be used.
The compositions contain 50 to 95, preferably 65 to 90% by weight of copolymers A), optionally in admixture with other binders or dispersions, and 5 to 50, preferably 10 to 35% by weight of crosslinking resins or mixtures of different crosslinking resins.
Examples of suitable crosslinking resins include amide- and amine-formaldehyde resins, phenolic resins, aldehyde and ketone resins (such as phenol-formaldehyde resins), resols, furan resins, urea resins, carbamic acid ester resins, triazine resins, melamine resins, benzo-guanamine resins, cyanamide resins and aniline resins, such as those described in xe2x80x9cLackkunstharzexe2x80x9d, by H. Wagner and H. F. Sarx, Carl Hanser Verlag Munich, 1971.
Also suitable as crosslinking resins are blocked polyisocyanates, for example, those based on isophorone diisocyanate, hexamethylene diisocyanate, 1,4-diisocyanato-cyclohexane bis-(4-isocyanatocyclohexyl)-methane and 1,3-diisocyanatobenzene; those based on lacquer polyisocyanates containing biuret or isocyanurate groups and prepared from 1,6-diisocyanatohexane, isophorone diisocyanate and bis-(4-isocyanatocyclohexyl)-methane; and those based on lacquer polyisocyanates containing urethane groups and prepared from 2,4- and/or 2,6-diisocyanatotoluene or isophorone diisocyanate and low molecular weight polyhydroxyl compounds such as trimethylolpropane, the isomeric propanediols or butanediols and mixtures of polyhydroxyl compounds of this type.
Examples of suitable blocking agents for these polyisocyanates include monohydric alcohols such as methanol, ethanol, butanol, hexanol, cyclohexanol or benzyl alcohol; oximes such as acetoxime or methyl ethyl ketoxime; lactams such as xcex1-caprolactam; phenols, and amines such as diisopropylamine or dimethylpyrazole.
The hydrophilic modification of copolymer component A) is generally sufficient to ensure the dispersibility of the crosslinking resins if these resins are not soluble or dispersible in water. Blocked polyisocyanates which are soluble or dispersible in water can be obtained, for example, by modification with carboxylate and/or polyethylene oxide groups.
Also suitable as crosslinking resins are low viscosity, hydrophobic or hydrophilic polyisocyanates which contain free isocyanate groups and which are based on aliphatic, cycloaliphatic, araliphatic and/or aromatic isocyanates. These polyisocyanates generally have a viscosity at 23xc2x0 C. of 10 to 3500 mPa.s. If necessary, the polyisocyanates can be used in admixture with small amounts of inert solvents in order to reduce the viscosity to a value within this range.
These polyisocyanates can be rendered hydrophilic, for example, by reaction with sub-stoichiometric amounts of monohydric, hydrophilic polyether alcohols. The preparation of hydrophilic polyisocyanates of this type is described in EP-A-540,985 for example. It is also possible to impart hydrophilic properties to polyisocyanates by the addition of commercially available emulsifiers.
Mixtures of different crosslinking resins can also be used in accordance with the present invention.
In one preferred embodiment, mixtures of a hydrophilic polyisocyanate and a low viscosity, hydrophobic polyisocyanate are used in combination with the dispersions according to the invention in aqueous two-component systems which are reactive at room temperature. Preferred mixtures are those containing 30 to 90% by weight of a hydrophilic polyisocyanate based on hexamethylene diisocyanate and 10 to 70% by weight of a hydrophobic polyisocyanate based on hexamethylene diisocyanate, isophorone diisocyanate and/or bis-(4-isocyanatocyclohexyl)-methane. Also preferred are mixtures containing 10 to 65% by weight of a low viscosity hydrophobic polyisocyanate based on hexamethylene diisocyanate and containing isocyanurate, biuret, allophanate and/or uretdione groups and 35 to 90% by weight of a hydrophilic polyisocyanate based on isophorone diisocyanate.
The term xe2x80x9clow viscosityxe2x80x9d means viscosities of 10 to 1500 mPa.s at 23xc2x0 C.
In another preferred embodiment, mixtures of hydrophilic polyisocyanates containing free isocyanate groups and amino crosslinking resins, which preferably do not contain free amino groups, are combined with copolymers dispersions A) and are cured, preferably at temperatures of 60 to 120xc2x0 C. These mixtures preferably contain 25 to 68% by weight of polyisocyanates containing free isocyanate groups and 32 to 75% by weight of amino crosslinking resins.
The known additives from lacquer technology can be added by mixing the individual components before, during or after the production of the aqueous binder combinations, even when the coating compositions are intended to be processed as one-component systems. Examples of these additives include anti-foaming agents, thickeners, pigments, dispersing agents, catalysts, anti-skinning agents, anti-settling agents and emulsifiers.
The coating compositions according to the invention are suitable for all fields of application in which aqueous paint, varnish and coating compositions requiring a high level of properties are employed, e.g., coatings for mineral-based building surfaces, coatings and sealants for wood and timber-based products, coatings for metal surfaces, coverings and coatings for roads based on asphalt or bitumen, and coatings and sealants for plastics.
The lacquers or coating media which are produced using the binder vehicle combinations according to the invention include primers, primer surfacers and pigmented or transparent covering lacquers, as well as single-coat lacquers which can be employed for one-off and mass-production applications, e.g. in the field of industrial lacquer coating, for the original lacquer coating of automobiles and the lacquer coating thereof for repair purposes.
The aqueous copolymers A) according to the invention are preferably used in combination with polyisocyanates and most preferably in combination with mixtures of hydrophilic and hydrophobic polyisocyanates for coating metal surfaces or plastics at temperatures from room temperature to 140xc2x0 C., or in combination with amino crosslinking resins for coating of metal surfaces at 110 to 180xc2x0 C., in the form of single-layer coatings or as covering lacquers.
The coating compositions can be applied by various spraying processes, such as compressed air, airless or electrostatic spraying processes, using one- or optionally two-component spraying installations. The lacquers and coating compositions can also be applied by other methods, for example, by brushing, rolling or by doctor blades.

Aqueous dispersions containing a mixture of copolymers and their use in binders


A computer-based method for construction portfolios, including: populate an initial estimated portfolio covariance matrix; generate initial configurations by populating covariance matrices with randomly selected assets; determine scores for the initial configurations; calculate a first statistical function for the scores; select an initial configuration satisfying a criterion regarding the statistical function; generate iteration configurations by successively replacing one asset with a randomly selected asset; determining a score for each iteration configuration; calculate a second statistical function of the scores; calculate a statistical function of the first and second statistical functions; select a starting cooled configuration; generate modified cooled configurations by replacing one asset when a score for the modified cooled configuration satisfies a criterion; and when a score for a modified cooled configuration satisfies a criterion, save, in a memory unit, the assets and weights of dividend factors of assets for the cooled configuration as a recommended set of assets.

FIG. 1 illustrates the minimum variance frontier of risky assets. FIG. 1 is based on FIG. 7.10 from the Bodie reference described below. Conventional Mean-Variance Optimization (MVO), as pioneered by Harry Markowitz, is well-known and has been used to construct portfolios for the last half-century. For an exposition see, for example, Investments, by Zvi Bodie, Alex Kane, and Alan J. Marcus (Irwin, (c) 1996), Section 7.4, "The Markowitz Portfolio Selection Model". Also see Portfolio Optimization, by Michael J. Best, (Taylor & Francis, (c) 2010). Under MVO assumptions, higher risk is associated with higher returns, leading to the well-known "efficient frontier"
FIG. 2 illustrates the risk-return plot for two overlapping 20-year time periods. FIG. 2 is based on FIG. 4.6 of Bernstein reference described below. MVO is known to be unstable in practice: see, for example, The Intelligent Asset Allocator by William Bernstein, (McGraw Hill, (c) 2001). Some "hints" (constraints) usually must be supplied to prevent the algorithm from chasing asset sectors with recent high performance. Another practical consideration is that in many cases investors are limited to long-only positions, either because of difficulties in obtaining credit for short positions, or because short positions are forbidden by statute or by investment policy (e.g. in some retirement accounts and pension plans).
Despite the theory, results from historical data tell a different story. The so-called "Low Volatility Anomaly" (LVA) has been documented extensively. See for example The New Finance—The Case Against Efficient Markets by Robert A. Haugen, (Prentice-Hall, (c) 1995). Also see: http://www.spindices.com/documents/presentations/20121106-global-webinar-spdji-kang-look-volatility.pdf
The data show that in many cases, a lower volatility stock portfolio is associated with higher returns: this is NOT what the well-known MVO risk/return tradeoff would have suggested.
After a number of years during which the existence, magnitude, and possible causes of the LVA have been debated, some recent ETF (Exchange-Traded Fund) offerings have been developed to market it. See for example: http://seekingalpha.com/article/1230991-low-volatility-landscape-gets-4-new-etfs and http://www.invescopowershares.com/products/overview.aspx?ticker=XSLV
One suggestion for incorporating this phenomenon into practical portfolio construction (as advocated for example by Haugen, for example, in Chapter Six of his book, Section "Value Man and Growth Man Too") is to use MVO "top-down" to determine a broad stock vs. bond mix, but to then use a low-volatility criterion for detailed stock selection.
Alternatively, risk-aversion and time horizon considerations can also be used to determine the top-down asset mix. See "Strategic Asset Allocation" (John Y. Campbell and Luis M. Viceira, Oxford University Press, (c) 2002), Chapter 3, esp. FIG. 3.3.
Small-cap stocks are especially attractive in the context of portfolio construction since they have historically enjoyed a long-term performance advantage over large-cap stocks. See for example the SBBI (Stocks, Bonds, Bills, and Inflation) 2006 Yearbook (Ibbotson Associates, (c) 2006) which shows that over the period 1926-2005, the geometric mean return on large company stocks was 10.4%, while for small company stocks it was 12.6%, giving small-cap stocks a 2.2% annualized advantage.
FIG. 3 illustrates the effect of moving to lower- and higher-risk portfolios. FIG. 3 is based on FIG. 6.16 from Haugen and shows that the estimated annual advantage of a low-volatility portfolio (what Haugen refers to as the "efficient version") is about 1%, and so, assuming additivity, approximately 3.2% of excess annualized performance (on average) is achievable.
FIG. 4 illustrates value versus growth in the U.S. from 1927-2006. FIG. 4 is based on FIG. 8.20 of the Hebner reference described below. Depending on the data source, it may in fact be that the improvement in returns is more than additive. See for example Index Funds: The 12-Step program For Active Investors, by Mark T. Hebner, (IFA Publishing, (c) 2007). The data cited in the Hebner book shows that the large blend vs. small value performance over 1926-2006 is 10.65% vs. 14.50%, an annual performance differential of 3.85%. This expected level of outperformance is an extremely attractive prospect for the long-term investor. However, practical implementation of a true minimum-variance portfolio may be very difficult.
The variance of a portfolio can be computed from the covariance matrix and portfolio weights as shown in, for example Investment Analysis and Portfolio Management, 4th. ed. by Jerome B. Cohen, Edward D. Zinbarg, and Arthur Zeikel, (Richard D. Irwin Inc., (c) 1982) Chapter 4, Appendix B.
Seeking an unconstrained minimum variance solution may be unstable (i.e. may lead to large positive and negative weights) and require more data than can be easily assembled. For example, portfolio optimization (as described in e.g. equation 2.6 of Best) requires inversion of the asset return covariance matrix. However, it is well-known that an n-by-n covariance matrix based on fewer than n observations will be rank-deficient and hence not invertible, and that even with n or more observations the matrix may be singular or nearly singular.
Take for example the problem of finding a minimum variance portfolio for the Russell 2000 Index, which is based on performance data for approximately 2,000 small-cap stocks. If daily closing data is assembled for each stock, then under the assumption of 250 trading days per year, it will take at least eight years to assemble a full-rank covariance matrix. This period of time is longer than a typical business cycle, raising the possibility that by the time the data is collected, it may be too late to make timely investment decisions based on it.
Additionally, for all but the largest funds, maintaining a position in each of 2,000 stocks may be expensive, and so some kind of sampling approach (investing in only a subset of the 2,000 stocks) is necessary. A method based on picking a relatively small number of stocks for the portfolio and adding them incrementally to the portfolio could substantially reduce transaction costs.
An equal-weighting approach reduces the difficulty of the optimization problem, avoids unstable and wildly differing portfolio weights for stocks in the portfolio, and automatically constrains the portfolio to be long-only. It can also be justified on the basis that more sophisticated methods may give statistically-indistinguishable results unless measurement is over a very long timescale. See Optimal Versus Naive Diversification: How Inefficient is the 1/N Portfolio Strategy?, by Victor DeMiguel, Lorenzo Garlappi, and Raman Uppal, (c) 2007 Oxford University Press, available at: http://faculty.london.edu/avmiguel/DeMiguel-Garlappi-Uppal-RFS.pdf
A refinement of the 1/N approach is to start with equal weights and then modify them within bounds (say 50% to 150% of the equal weights), to further reduce volatility. This "modified equal-weighting" approach avoids the unstable portfolio weights arising from an unconstrained minimization approach while making fuller use of the data, and is computationally within a constant factor of the amount of time it takes to determine the volatility of the 1/N portfolio.
But even after applying the equal-weighting approach or the modified equal-weighting approach, the solution space is very large. If we are selecting 50 equally-weighted stocks from a set of 500 (for example) with the objective of minimizing variance, there are C(500,50)=2.3×1069 combinations to consider, while if selecting 50 stocks from a set of 2000 there are C(2000,50)=2.0×10100. Clearly, exhaustive search of all possible combinations is impractical.
However, if there were a practical, even if approximate, solution to this problem, it could be iterated: pick the next-lowest variance basket of 50 stocks repeatedly until a stopping criterion (such as selection of 25% of all stocks in the original set) is satisfied.
Accordingly there is a long-felt need for a system allowing incremental construction of an approximate minimum-variance modified-equal-weight portfolio of size m, given an n by n possibly rank-deficient covariance matrix of asset returns, where m is less than n.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Method and system for constructing approximate minimum variance portfolios


This invention is directed to dish drainers, which have integrally formed connecting elements in the basket and pan thereof.. The connector elements are used to maintain the basket and pan coupled together during shipment, when displayed for sale or when in use. The connector may be disconnected to separate the pan from the basket in order to clean the dish drainer components.

This invention is directed to a new and improved dish drainer. Dish drainers are widely used in the kitchen to permit washed dishes, glasses, cups and utensils to drip dry after washing.
Dish drainers comprise two separate units, the upper being called the basket (rack) and the bottom being called the pan. The basket normally sits on the pan, which catches the water from the washed dishes, etc., and directs the water into the adjacent sink.
In shipping the dish drainers, it is today commonplace that they are placed in packaging in an attempt to hold the basket and rack together for future sale. In most instances, a plastic shrink wrapping and a corrugated board are used for this purpose. This constitutes additional, non functional components that add to the cost of the product and present a problem in recycling due to the type of plastic film and cardboard required. Todays environmental concerns are focused on reducing or eliminating all difficult to recycle packaging. If the basket and rack are not held together properly, they will separate when displayed for sale, causing product rejection.
Users also find that the basket, particularly when not loaded with dishes will move on the pan. When the pan and basket are tilted to drain off excess water into the sink, an unsecured basket will slide forward and in some cases, will slide into the sink.
The present invention provides a solution to the aforementioned disadvantages noted above.


A screening assembly is provided including a closed housing having an inlet and a first outlet, and a second outlet. A screen drum having a plurality of circumferential slots is mounted for rotation in the housing so that liquid passing from the inlet to the second outlet must pass through the drum slots. A a barrier member mounted on a short housing segment between the inlet and first outlet prevents short-circuiting of suspension flow from the inlet to the first outlet, and also includes a plurality of comb-like teeth extending into the drum circumferential slots. The barrier member has concave surface portions thereof adjacent the suspension inlet and outlet. The drum has a plurality of circumferentially spaced grooves or raised portions formed in or on the exterior surface thereon and extending substantially parallel to the axis of the rotation of the drum. The center lines of the inlet and first outlet preferably make an angle of about 45.degree.-90.degree. with respect to each other, and the second outlet is perpendicular to a plane containing the inlet and first outlet.

The present invention relates to a screening assembly that is designed to be simple and versatile being relatively inexpensive to construct and maintain, and having a minimum number of component parts to perform the necessary operations. Prior art screening assemblies have been effective in performing their ultimate function, however they often are too bulky for many types of uses and environments and can be unnecessarily complicated.
The simplicity and versatility of the present invention are readily apparent when the small number of component parts thereof are considered, and when it is considered the assembly according to the invention may be used in many situations and environments. The screening assembly according to the present invention is capable of separating out knots, fiber bundles, shives and scrap material from suspensions of cellulosic fiber material having consistencies on the order of 8 to 10%, and can accomplish this without any air introduction so that no foam is developed, and can accomplish this without interruptions due to clogging of the screening element.
According to the present invention a screening assembly is provided comprising a closed housing having an inlet, a first outlet, and a second outlet. While the terms "inlet" and "outlet" are used in the present specification and claims for convenience, it should not be assumed that the recited elements can be used only as inlets or outlets, or always function as such. The screening assembly according to the invention further comprises a screen drum mounted for rotation about an axis and having a plurality of circumferential through-extending slots formed along the exterior periphery thereof, and disposed in planes substantially perpendicular to the axis of rotation.
Means are provided for rotating the drum about its axis of rotation, and means are provided for mounting the drum for rotation about its axis within the housing so that suspension passing from the inlet to the second outlet must pass through the drum slots, the second outlet being essentially coaxial with the drum, and so that suspension flows pass the drum from the inlet to the first outlet. Means are also provided for preventing short-circuiting of suspension flow from the inlet to the first outlet, and for dislodging suspension particles caught within the drum slots. Such short-circuiting preventing and particle dislodging means may comprise a single component, such as a barrier member mounted on a short housing segment between the inlet and first outlet, and having a plurality of comb-like teeth extending into the drum circumferential slot. The barrier member preferably has concave surfaces formed on portions thereof adjacent the inlet and first outlet to facilitate directing the suspension.
The inlet and the first outlet preferably lie in a common plane, each having a center line, and the housing preferably connects the inlet and the first outlet so that the center lines thereof make an angle of about 45.degree.-90.degree. with respect to each other. The second outlet preferably is disposed perpendicular to the common plane containing the inlet and the first outlet.
The drum preferably has a plurality of axially extending surface manifestations formed thereon to facilitate transportation of the suspension being screened by the drum. Such surface manifestations may comprise of a plurality of circumferentially spaced grooves, or a plurality of circumferentially spaced raised portions.
In addition to the barrier member, accessory cleaning devices may be provided spaced from the barrier member around the circumference of the drum, and having a plurality of comb-like teeth extending into the drum slots to effect dislodgement of suspension particles therefrom. Such a cleaning device or devices are mounted and dimensioned to allow passage of suspension therepast from the inlet to the first outlet.
It is the primary object of the present invention to provide a simple, versatile, and effective screening assembly. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.


The process for applying a thermally attached lubricating coating on an interior wall of a cylindrical medicinal container includes applying a thermally attachable lubricant to an interior wall of the container; uniformly spreading or homogenizing the applied lubricant on the wall to form a lubricating coating and thermally attaching the lubricating coating by irradiating the lubricating coating with infrared radiation selectively in a cylindrical region of the container at elevated temperatures above a maximum operating temperature of the container. The apparatus for performing the process includes an insertable spraying device for applying the thermally attachable lubricant (3) to the interior wall of the container (1) from a supply reservoir; a device for homogenizing the lubricant to form the lubricating coating (4) and a rod-shaped infrared radiation source (5) insertable into an interior space of the container. The radiation source has a radiation screen (5a, 6, 7) for keeping the radiation away from the container outlet.

1. Field of the Invention
The present invention relates to a process for applying a thermally attached lubricating coating to the interior wall of a cylindrical medicinal container, which has a tapered outlet on one end and a slidable elastomeric stopper acting as a plunger or piston at the other end of the container. The invention also relates to an apparatus for performing this process.
2. Related Art
Containers for medicinal purposes, especially pharmaceutical containers or containers for diagnostic purposes, have slidable elastomeric closure devices, such as pistons or piston stoppers. The slidable elastomeric closure device for these containers is inserted in an interior chamber in a hollow body of the container and slides lubricated on an interior wall of the hollow body. Syringe cylinders of fillable syringes, injector bodies of cylindrical ampoules and containers are typical examples. However other examples include the piston burettes used in analytical chemistry. In order to solve this problem correctly a silicone-lubricating coating is often applied to the interior wall of the hollow body.
The fillable syringes are of special significance here. Fillable syringes made from glass have been disclosed and are known from many years from numerous publications. These fillable syringes comprise glass, which does not have an integrated needle. Glass syringes with attached needles are notoriously well known.
This sort of fillable syringe made from glass requires a lubricant between the movable elastomeric piston or plunger and the glass syringe cylinder. Silicone oil is preferred for this purpose. This silicone oil is usually applied by washing the interior of the injector cylinder. Great differences exist between the processing syringe bodies with and without needles. Since the needle is usually attached with glue, such as epoxy resin, or other adhesives, that have limited heat resistance different process conditions are required.
A maximum processing temperature of 130xc2x0 C. is allowed at the site of the glue or adhesives in finished syringes with hollow needles attached with an adhesive or glue. An adherent lubricant coating is only guaranteed however, when the lubricant, preferably silicone, is applied at temperatures of about 300xc2x0 C.
Thus it is known to provide a glass syringe cylinder with a silicone coating at about 300xc2x0 C. and then subsequently to connect a needle-supporting piece with the syringe body that is made from glass. However this method requires additional assembly effort and thus additional costs, which make it considerably disadvantageous, because it is a mass-produced product.
If a silicone lubricant coating is applied to a syringe with a needle already attached to it, there is a risk that the often very narrow needle duct is filled with silicone lubricant, which can lead easily to unintended injection of silicone oil in application.
This problem also exists in pre-filled plastic syringes. DE 197 53 766 A1 describes a method for providing containers for medicinal purposes with an interior silicon coating. These containers comprise an elongated plastic hollow body, especially a syringe cylinder. The silicone coating is provided by special reactive silicone oil, which hardens under the influence of light. This method avoids the otherwise conventional step of pre-conditioning the interior surface, e.g. by plasma treatment.
It is an object of the present invention to provide a process of the above-described type for providing a thermally attached lubricating coating on an interior wall of a cylindrical medicinal container, which has a tapered outlet at one end and an elastomeric stopper at the other end, which is slidable like a piston in the container, which process is conducted, so that a thermal bonding of the lubricant to the interior wall is possible at very high temperatures without damage to temperature sensitive parts at the outlet end of the container.
It is another object of the present invention to provide an apparatus for performing the improved process according to the invention.
According to the invention this process comprises the steps of:
a) applying a thermally attachable lubricant to the interior wall of the container in a known manner;
b) homogenizing the applied lubricant on the interior wall to form a lubricating coating; and
c) thermally attaching the lubricating coating by irradiating the lubricating coating with infrared radiation selectively in a cylindrical region of the container at elevated temperatures above a maximum operating temperature of the container.
The apparatus for performing this process according to the invention comprises
means for applying the thermally attachable lubricant from a supply reservoir to the interior wall of the container;
means for homogenizing the lubricant applied by the means for applying to form the lubricating coating; and
a rod-shaped infrared radiation source insertable into an interior space in the container, said radiation source having a radiation screen or barrier for keeping the radiation away from the container outlet.
By means of selective heating of the container wall with the infrared radiation the lubricating coating or layer applied to it can be reliably attached in a simple manner and at a high temperatures, while the outlet of the container remains free of lubricant and the attachment of the syringe or injector needle is not damaged. At the same time the germ count and the endotoxins are reduced because of the high temperatures. Furthermore the method according to the invention does not require pre-conditioning of the surface to which the lubricant is applied, e.g. by plasma treatment.
The method according to the invention and the apparatus for performing that method are thus advantageous for applying a thermally attached lubricating coating, especially a silicone coating, both to glass or plastic syringe bodies with integral needles and without integral needles.
Preferably the silicone oil used as the lubricant in the method according to the invention should be reactive silicone oil, non-reactive silicone oil or a mixture of both types of silicone oil. Other thermally fixable or attachable lubricants can be used.
According to a preferred embodiment of the invention the lubricant is applied by spraying, which leads to a relatively uniformly wetting silicone coating in a very simple manner. However other known methods for applying lubricants, especially silicone oils, are also conceivable.
The temperature range for the thermal attachment, among other things, depends on whether or not a glass or a plastic container is to be coated. The temperature range is preferably at about 300xc2x0 C. in the case of glass containers.
For plastic containers the thermal attachment should be performed in a temperature range, which is about 50xc2x0 C. above the maximum operating temperature of the plastic container.
For selective irradiation of the interior wall of the container the rod-shaped infrared radiation source has a preferably top-side covering member in the form of a cylindrical cap acting as a radiation screen or shield. Alternatively the screen can be a mushroom-shaped body, which is attached with its stem to the top end of the radiation source and which keeps the infrared radiation away from the outlet of the container. Other forms of the screen or shield are conceivable.

Process and apparatus for applying a thermally attached lubricating coating on an interior wall of a cylindrical container for medicinal purposes


Disclosed are four gel compositions that have improved properties over the prior art. These gels include elastosols, solid rubbery gels, UV cured gels and chemically cured gels. The gels are formed from selectively hydrogenated styrene/diene block copolymers, unhydrogenated styrene/diene block copolymers, and selectively hydrogenated styrene/diene block copolymers that have been maleated.

1. Field of the Invention
The present invention relates broadly to gel compositions. The present invention particularly relates to elastosols, solid rubbery gels, UV curable gels and chemically curable gels.
2. Background of the Art
Gel compositions are well known in the art and are known to be useful in making many types of products. For the purposes of the present invention, a gel is a solid and rubbery material. Gels are useful for preparing articles such as clear oil gel candles, when combined with oil, or air fresheners, when combined with a volatile solvent and a fragrance. Other applications of such gels are the formation of soft articles such as gaskets, cushions and toys.
While gels are well known, there continues to be discovered new applications and corresponding new requirements for gels. This has led to a significant increase in the need to improve gel properties, and hence, has led to new opportunities for novel gel compositions. For example, in U.S. Pat. No. 6,881,776, two-phase gel compositions are shown. However, the resulting gels are generally too soft or even liquid in some cases, which may be useful for some applications but not for all applications. What would be needed for some applications would be solid rubbery gels. In another example, U.S. Pat. No. 5,900,445 teaches a method for preparing elastosols. However, the elastosols of the '445 patent do not have the necessary properties at high temperature that are needed for certain applications such as sealants that will stay in place in automotive paint baking ovens. Likewise, certain UV cured and chemically cured gels are known, yet improvement needs to be made in the way the gels are prepared.
New gel compositions are required to meet the ever changing and ever demanding applications that are being developed. The present invention addresses some of those applications, by proposing new compositions and methods for making such compositions.


This invention relates to polymer blends having improved hydrolytic stability, moldability, fire retardancy and dielectric strength which comprise, in admixture, (1) a linear aromatic polyester prepared from an aromatic dicarboxylic acid and bisphenol, and (2) polyphenylene sulfide. Such blends have a weight proportion of the polyphenylene sulfide in the range of above about 5 weight percent to less than about 60 weight percent, based on the admixture of the sulfide polymer and the polyester.

This invention relates to blends of polyphenylene sulfides and linear aromatic carboxylic polyesters comprising a bisphenol wherein the carboxylic acid component can be an aromatic dicarboxylic acid or an aliphatic saturated dicarboxylic acid such as oxalic or adipic acids.
Linear aromatic polyesters prepared from aromatic dicarboxylic acids and bisphenols are well known for their stability for molding, extrusion, casting, and film-forming applications. For example, U.S. Pat. No. 3,216,970 to Conix, disclose linear aromatic polyesters prepared from isophthalic acid, terephthalic acid, and a bisphenolic compound. Such high molecular weight compositions are known to be useful i the preparation of various films and fibers. Further, these compositions, when molded into useful articles using conventional techniques, provide properties superior to articles molded from other linear polyester compositions. For instance, aromatic polyesters are known to have a variety of useful properties, such as good tensile, impact, and bending strengths, high thermal deformation and thermal decomposition temperatures, resistance to UV irradiation and good electrical properties.
Aromatic polyesters which are particularly well suited for molding applications may also be prepared by reacting an organic diacid halide with a difunctional aliphatic reactive moldifier, such as glycol, and subsequently reacting this product with a bisphenol compound. The resulting polyesters have reduced melt viscosities and melting points which permits molding at temperatures within the operable limits of conventional molding apparatus (i.e. less than about 300.degree. C.). This type of glycol-modified polyester is more fully disclosed in U.S. Pat. No. 3,471,441, to Hindersinn.
In order to form a successful molding resin on a commercial scale, a polymer should be capable of being molded conveniently without significant degradation in physical properties. In this respect, although the aforementioned aromatic polyesters generally display excellent physical and chemical properties, a persistent and troublesome problem has been their sensitivity to hydrolytic degradation at elevated temperatures. This sensitivity to the combined effects of heat and moisture is also exhibited in commercially available polycarbonate resins as evidenced by the desirability to reducing the water content of the resin to less aromatic polyester resins often display a more pronounced tendency to rapidly degrade and embrittle than do polycarbonate resins. This is demonstrated by the loss of tensile strength which can occur when an aromatic polyester resin is molded and subsequently immersed in boiling water. This tendency may be explained, in part, by the hydrolysis of the ester linkages under these conditions. In any event, it is to be appreciated that sensitivity to moisture represents a significant problem in aromatic polyester resins that would significantly limit their commercial utility in applications such as in autoclaves or at elevated temperatures in humid atmospheres.

Polymer blends with improved dielectric strength


A method is disclosed for filtering a protein in a liquid mixture in a manner that does not substantially damage or otherwise limit the recovery of the protein in the filtration filtrate. The method generally includes passing a liquid mixture containing a protein (e.g., an aqueous vWF mixture) through a filter while applying a counter pressure to the liquid mixture filtrate to accurately reduce and control the pressure differential across the filter. The disclosed method has the advantage that relatively high filtration flow rates can be achieved at relatively low pressure differentials, in contrast to high pressure differentials, which actually reduce the filtration flow rate of protein liquid mixtures. Further, the method can recover substantially all of the protein that is initially present in the liquid mixture.

1. Field of the Disclosure
The disclosure relates generally to filtration methods for the purification of proteins. More particularly, the disclosure relates to the low-shear, counter-pressure sterile filtration of proteins susceptible to damage by shear forces (e.g., shear-sensitive proteins, blood coagulation cascade proteins), for example when being transported in a fluid.
2. Brief Description of Related Technology
Purified protein mixtures can be administered to patients for a variety of therapeutic uses. A purified protein mixture prepared for infusion into patients must be sterilized prior to use. A suitable sterilization process for some proteins includes membrane filtration of a purified protein mixture. The filter membrane can be sized to retain (i.e., remove from the protein mixture) particulates, microorganisms, and some viruses, while the proteins are able to pass through the membrane.
However, some proteins are not efficiently recovered as purified, sterilized proteins using conventional methods such as membrane filtration. This effect is most pronounced when attempting to filter proteins that are shear-sensitive and/or part of the blood coagulation cascade. An example of such a protein is the von Willebrand factor (vWF), which circulates in plasma complexed with factor VIII and assists in the regulation of biological blood coagulation activity. Specifically, the vWF proteins are sensitive to shear forces induced by the velocity gradient of a transporting fluid medium, in particular when the vWF proteins pass through or near a filter membrane (i.e., where flow constrictions and circuitous flow paths in the neighborhood of filter membrane pores result in particularly large velocity gradients). Thus, when filtration units are operated at sufficient pressures to ideally generate desirable process flow rates, increased flow rates (and the accompanying increase in induced shear forces) tend to reduce process yield, for example by damaging or destroying the proteins, and/or by reducing the filtration rate over time.
Accordingly, it would be desirable to develop a method of filtering a purified vWF mixture in a manner that does not substantially damage the vWF proteins, yet which method still permits a suitably high process throughput (i.e., filtration rate) over time. Additionally, it would be desirable to develop a filtering method generally applicable to any protein, such that the general protein can be filtered (e.g., sterile filtered) at an efficient rate without incurring substantial damage to/loss of the protein.

This patent is subject to a terminal disclaimer.


Hybrid and commingled yarns containing reinforcing fibers and thermoplastic matrix fibers when sized with a dispersion or emulsion having a dispersed phase containing a thermoplastic compatible with the thermoplastic of the matrix fibers but having a lower melting point allow preparation of thermoplastic matrix fiber reinforced composite structures at reduced consolidation temperatures, cycle times, and/or consolidation pressures without loss of composite physical properties.

1. Field of the Invention
The present invention pertains to the field of fiber-reinforced thermoplastic composites. More particularly, the invention pertains to an improved process for preparing such composite structures wherein the time required to fully consolidate the composite is reduced significantly, and to the products produced thereby. This improvement is achieved through the use of commingled yarn containing reinforcing fibers and thermoplastic matrix fibers which have been sized with an emulsion or dispersion of a thermoplastic which is melt-compatible with the thermoplastic fibers but which has a melting point significantly lower than the thermoplastic matrix fibers.
2. Description of the Related Art
Thermoplastic matrix fiber-reinforced composites are now well known items of commerce. Such products may be prepared by numerous methods. Glass mat reinforced polypropylene composites, for example, are prepared by impregnating needled or non-needled continuous or chopped fiber layers with molten polypropylene to form an intermediate, somewhat lofty product, which may then be consolidated under heat and pressure to form composite structures having a thickness considerably lower than the intermediate product. Such products are particularly useful in the transportation industry for body panels and engine covers. Complex shapes are difficult to achieve with this process.
A similar process is resin transfer molding. By this process, a plurality of fiber-reinforced laminae interspersed with sheets of thermoplastic or having thermoplastic sheets exterior to one or both sides of the laminate layup are consolidated under heat and pressure whereupon the thermoplastic flows into the fiber reinforcing laminae. Such products often do not have the same physical properties as thermoplastic composites formed from thermoplastic impregnated fiber-reinforced prepregs.
The use of thermoplastic impregnated fiber reinforced prepregs is now commonplace. Such prepregs are stacked together and consolidated under heat and pressure. However, because the prepregs themselves are stiff and "boardy", it is difficult and in many cases impossible to prepare composites which are other than planar or modestly curvilinear.
Improvements in forming thermoplastic composites of complex shapes are illustrated by the use of thermoplastic powder impregnated prepregs and the use of hybrid or commingled yarns. In the former case, unidirectional or woven fiber reinforcement is impregnated with the necessary quantity of thermoplastic in the form of a fine powder. A binder, generally a high molecular weight polyoxyethylene glycol, polyvinylalcohol, polyacrylate, polyvinylpyrollidone or similar water or alcohol soluble polymer is usually necessary to provide integrity, particularly with unidirectional fibers, and to prevent loss of the thermoplastic powder from the prepreg during shipping and handling. The presence of the binder can result in an undesirable decrease in composite physical properties. Such powder impregnated prepregs, however, can be utilized to prepare composites of complex shapes due to their drapeability, particularly when wet.
Hybrid and commingled yarns have also proven successful in preparing composites of complex shapes. In the remainder of the specification, the term "hybrid yarn" will be used to define yarns which are combinations of reinforcing fibers and thermoplastic matrix fibers, whether truly commingled, i.e. having relatively statistical or uniform distribution of the different fiber types; or whether served, core/shell, partially commingled, or co-wound. Of course, commingled yarns are the preferred hybrid yarns. The term "thermoplastic matrix fibers" refers to the hybrid yarn fibers which will fuse during consolidation to form the thermoplastic matrix to distinguish these thermoplastic fibers from thermoplastic fibers which may serve as reinforcing fibers, and which do not fuse during consolidation.
Commingled yarns may be prepared as disclosed in U.S. Pat. Nos. 4,799,985 and 4,818,318 which are herein incorporated by reference. In general, fiber reinforcing tows are spread to form a unidirectional tape while thermoplastic tows are similarly spread and superimposed upon the fiber tape generally under low or relatively modest pressure. Combs or air jets are then utilized to more thoroughly intermix the reinforcing and thermoplastic fibers whereupon the commingled tape is then reformed into a commingled tow or yarn. In some cases, a slight twist is imparted to the yarn to aid in maintaining its integrity. The commingling produced by this process results in a product having a uniform distribution of reinforcing fibers and thermoplastic fibers. This uniform distribution is important, as the physical properties of consolidated structures decrease when non-uniform fiber distribution occurs, a condition aggravated as the melt viscosity of the thermoplastic increases. While cowound yarns (essentially not commingled) have been used with low melt viscosity thermoplastics such as the aliphatic nylons, even here the commingled yarns produce composites with superior properties when compared to cowound yarns of the same composition.
In order to weave or braid hybrid and commingled yarns, a certain degree of yarn integrity is necessary. Limited success has been achieved by twisting the yarn, for example at 0.2-0.8 twists per centimeter. However this level of twist is not totally satisfactory since it tends to damage the delicate reinforcing fiber filaments. Moreover, the composite properties are reduced due to the twist. To assist in fiber integrity, sizes may be applied. However use of traditional sizes such as polyoxyalkylene polyethers, polyvinylpyrollidone, polyvinylalcohol, polyvinylacetate, polyacrylates and the like, while capable of preparing tow with improved weaving and braiding characteristics, again results in a decrease in physical properties which may be severe at times depending on the chemical makeup of the size. This decrease in physical properties becomes more severe as the level of size increases. However, even when such sizes are applied at practical levels, moderate twist must often be applied to further assist yarn integrity.
The commingled yarns produced as described above may be woven into fabric "prepregs" or braided into a variety of braided "prepregs" including ribbons, ropes, and hollow tubular braids. In the preparation of composite products, one or more of such prepregs are laid up together and consolidated under heat and pressure. The time required for full consolidation varies with the melt viscosity of the thermoplastic, the degree of commingling, and the pressure applied. Lengthy consolidation times are commonplace, especially with non-planar structures which do not lend themselves to application of high consolidation pressures. These long consolidation times increase the cost of the finished products.
It would be desirable to devise a process whereby the twist imparted to commingled yarns could be reduced significantly or avoided entirely, and where any size applied would not significantly lower physical properties of the finished composite. It would further be desirable to lower the consolidation time and/or pressure in order to produce finished products in a shorter time and/or at less expense.

Process for preparing thermoplastic matrix fiber-reinforced prepregs and composite structure products formed thereby


A high resolution digital to analog conversion system using a medium resolution converter compensated for error correction. The errors of more significant bits are stored in a memory during correction mode and recalled during normal operation. The errors are evaluated by comparing the binary weighted currents of a sub-DAC with corresponding reference currents and stored in the memory. The comparing operation is exercised by sequential approximation method for fast execution and simpler circuitry.

Recent papers and patents on high resolution digital to analog (D/A) conversion technique have proposed trimmed analog device, reference refreshing cyclic method and dynamic element matching method, etc. However, because of the stringent requirement and the lack of satisfactory algorithm, the conversion rate has not achieved high speed.
In U.S. Pat. No. 4,465,996, Boyacigiller etal proposed a method for error correction. A high accuracy digital to analog converter (DAC), which employs an EPROM to store the error values, was used to correct the errors in the output of a primary DAC. It also corrects the error by an overlapping correction method such that the error of every quantum level can be corrected.
Maio etal proposed a D/A conversion technique (in IEEE Journal of Solid State Circuits, Vol. SC-16, No. 6, Dec. 1981 "An Untrimmed D/A Converter with 14-Bit Resolution"), which features that correction values obtained from an Error Detection Circuit are stored in a RAM after comparing with the output of a Ramp Function Generator and the main DAC. In normal operation when there are input data, the corresponding correction is fetched from the RAM and then sent to a sub-DAC for correcting the output of the main DAC.
Both these methods have shortcomings. Boyacigiller's method is not automatic. Maio's method has the following drawbacks: (1) the self-calibration is not easy to accomplish; (2) an offset must be added to allow for additive and subtractive correction; (3) correction time for compensation is long; (4) the linearity of sub-DAC and Ramp Function Generator must match exactly.

Error correction system for digital to analog converters

Industrial Technology Research Institute, R.O.C.


An optical film constituted by a laminate of a polarizer and a reflective polarizing film through an acrylic-based pressure-sensitive adhesive agent, the polarizer having an anti-glare layer, wherein the optical film has a haze (H) in a range of from 5% to 30%. Preferably, a haze (H1) of the polarizer and a haze (H2) of the reflective polarizing film satisfy the relation H1>H2. Preferably, the haze (H) of the optical film satisfies the relation H/H1>0.5.

1. Field of the Invention
The present invention relates to an optical film used in a liquid-crystal display device (LCD) or the like. More specifically, it relates to an optical film adapted for improvement in display characteristic and luminance, and a liquid-crystal display device using the optical film.
2. Description of the Related Art
An LCD is used in a personal computer or the like. There has been a rapidly increasing demand for the LCD in recent years. Measures to make all constituent members of the LCD thin to thereby make the LCD thin as a whole have been examined. One of the constituent members which has been improved most remarkably in terms of reduction in thickness is a backlight unit. The backlight unit used in a liquid-crystal panel is constituted by a laminate of various films such as a laminate of a light pipe, a diffusing plate and a condensing sheet. Accordingly, interference or sticking caused by lamination of films looks like a defect when an image is displayed. Particularly the necessity for making the constituent members of the backlight unit (such as a light pipe, a diffusing plate and a condensing sheet) thin, reducing clearances between the members or removing some of the members for the sake of simplification has occurred with the strong requirement of reduction in thickness of the liquid-crystal panel in recent years. Hence, there a rises a problem that a defect or a sticking portion due to interference fringes (Newton's rings) or sticking caused by lamination of films is made visible when an image is displayed. On the other hand, both reduction in thickness of the backlight unit and improvement in definition of display lead to reduction in luminance of the panel, that is, go against the recent tendency to increase in luminance of the LCD panel. Therefore, a luminance enhancement film becomes essential to supply required panel luminance.
Although measures to insert a diffusing plate between the backlight unit and the liquid-crystal panel or to provide a diffusing layer in the luminance enhancement film or the polarizer itself have been heretofore taken to make the aforementioned defect invisible on the display, the measurements could not satisfy the requirement of reduction in thickness, retention of necessary characteristic and reduction in cost.

Optical film and liquid-crystal display device using the optical film


A water ski fin extends through the rear of a water ski. Pivotally connected to a lower portion of the fin is a wing extending substantially perpendicularly from the fin. A device is connected to the wing that allows the wing to pivot and change its angle of attack as a function of the speed of the fin through the water.

This invention relates to water sports equipment and more particularly, to finned water skis for controlling the stability during operation.
Conventional water skis include a fin or rudder mounted to the rear on surface portions of the ski. These fins make it easier for the skier to control his skis.
It has been found that slippage of the rear fin can be reduced by providing horizontally extending wings that extend outward from this fin. These wings can act as breaks to help maintain precise control of the ski. Two wings are typically mounted on the fins at fixed angles.
Angular positions can significantly effect the performance of the skis. Examples of a fin having a fixed manually adjustable angular position is disclosed in U.S. Pat. No. 4,439,166, which is hereby incorporated by reference.
Ideally, it is desirable to maintain a variable angle of the wing with respect to the speed of water past the wing. A wing at a fixed angle can cause unwanted drag and a degradation of ski performance as the speed of the ski increases.


Embodiments include a method of adding first and second binary numbers having C bits and divided into D words to provide a third binary number in E successive adding operations, C, D and E being plural positive integers, the method comprising: a first group of D adding operations adding together respective words of the first and second binary numbers to provide D sum and carry outputs ranging from a least significant to a most significant sum and carry output; one or more subsequent groups of adding operations adding together sum and carry outputs from an immediately preceding group of adding operations, a final group of the one or more subsequent groups resulting in the third binary number consisting of the sum outputs from the final group and a carry from the most significant carry output of the final group, wherein E is less than D.

Intelligent Transport Systems (ITS), as defined by Directive 2010/40/EU, are systems in which information and communication technologies are applied in the field of road transport, including infrastructure, vehicles and users, and in traffic management and mobility management, as well as for interfaces with other modes of transport (Article 4(1) of the ITS Directive). In this context, reliable vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication is an essential element. Such communication is used for both real time exchange of safety messages between vehicles and with infrastructure to resolve potentially dangerous road situations as well as to exchange essential information to improve traffic. V2V/V2I communication is based on the IEEE 802.11p standard, which is an amendment to the IEEE 802.11 standards to add wireless access in vehicular environments within the designated ITS band of 5.85 to 5.925 GHz.
Security of any communication links within ITS is clearly fundamental to prevent unwanted, wrong or misleading information. Security is predominantly used to authenticate that messages are coming from trusted sources, and therefore the information they carry can be trusted as well. This can be done using asymmetrical keys where a sender signs a message using their secret private key and a recipient can verify that the signature and message are coming from that particular sender using the sender's known public key corresponding to the private key.
The most widely known and used type of public key cryptography is RSA, based on the asymmetric difficulty of multiplying two large prime numbers and factorising the resulting number without prior knowledge of its factors. The two large prime numbers forms the basis of a private key, as this provides the solution to the factorisation problem, while the product can form the basis of a public key, whose knowledge cannot be used to easily determine the two prime factors. Another type of public key cryptography is known as Elliptic Curve Cryptography (ECC), which has been proposed for use in ITS, the main reason being that ECC keys and signatures are of much shorter length while still providing the same level of security as much longer keys in alternative approaches such as RSA. This property minimizes overhead in communication taking into account that the signature and the public key needs to be communicated with each message. Both types of cryptography require large numbers to be multiplied together as part of the verification process.
An ECC scheme is determined by key length and the chosen underlying curve. Typical ITS key lengths considered are, for example, 256 bits, 384 bits or 512 bits. The NIST (P256, P384, P512) curves are also used in ITS predominantly, but other choices such as Brainpool curves may be used. In ECC, the main algorithm for signing messages and verifying the signatures is called the Elliptic Curve Digital Signature Algorithm (ECDSA).
In ITS V2V or V2I (which may be encompassed by the general term V2X, or vehicle to everything), cars are typically broadcasting safety messages at rates of tens of messages per second (e.g. 10-20 Hz). A particular car may be receiving messages from hundreds (e.g. 100-200) of other cars and therefore needs to receive and authenticate thousands of messages a second (e.g. 1000-2000). Therefore, the speed of authentication computations is an important parameter in ITS, as this will determine how many messages can be authenticated and used for safety or traffic management applications and how many other cars a particular car can trust and consider in road situations.
Authentication computations, for example using ECDSA, are based on computation of large numbers (e.g. 256-512 bits and beyond). Basic computations involve multiplications, additions and subtractions of large numbers. Most other operations (including division) are based on these three operations. Considering that both multiplication and subtraction (in general, of large numbers in particular) are based on addition, a fundamental point is that addition of large numbers is a major contributor to computation times in large number arithmetic operations.


The present invention provides an arrangement of fastening elements for holding bundles retained by cable ties, and a method therefor. The arrangement of elements includes a pair of strips removably attached to a sequence of fastening elements, whereby the pair of strips facilitate the transport, readying, and positioning of each fastening element prior to interaction with the cable tie. Also provided is a method for molding the arrangement of cable ties in which the cable ties are advantageously used for retaining bundles of cables, pipes, and similarly elongated items.

Following the assembly of the cables and the insertion and cinching of the cable tie in the locking component, a separate plastic fastening element should be used for retaining the bundle, as disclosed in DE 94 01 448 U1. For the positive threading of the cable tie, this fastening element has a holding loop with its fastening plate anchored on an appropriately formed support part. Here it has been shown to be advantageous when the threading of the cable tie into the holding loop and the positioning of the tie in the holding loop are manually accomplished by means of a pin. This operation, however, is not only time consuming (and therefore costly), but also requires dexterity.
The use of binding devices for processing continuous sequences of cable ties via automatic feed prior to interaction with locking components results in difficulties threading the cable tie through the holding loop of the fastening element, both before and after the assembly of the bundle of cables. Also, costly vibrator conveyors with appropriate guide channels are needed for the exact positioning element and the guiding in front of the tie exit opening of the binding device.
Accordingly, it is the objective of the invention to economically design and coordinate the fastening elements so that a supply of the fastening elements can be transported and positioned correctly for efficient processing in the binding device.
The present invention overcomes the issues of the prior and current art, and meets the aforementioned objectives with the design of the fastening elements and their pull-off union with strips. The pair of strips serves as the transport strips in the automatic operation. It is then possible for the fastening elements to be supplied to the binding device as a group in a position favoring further processing and, following their separation from the strips, to be favorably positioned for threading the cable tie.
In order to create better preconditions for the automatic processing of the fastening elements in the binding device, additional means such as a rack profile on one surface of each strip enhance the transport of the strips or make it possible for several groups of fastening elements arranged in rows to be combined in a chain of any desired length when injected in the casting mold and then subsequently rolled up, so that a great supply of fastening elements is available.
The foregoing examples represent several of the embodiments of the present invention; however, one skilled in the art will recognize that the examples in no way limit the invention disclosed herein.
Described in DE 41 05 460 C2 is a process for arranging cable binders in a so-called tie cluster for use in a binding device, in which the individual ties are end-bonded by injection. Here the bundling ties aligned one after the other in the longitudinal direction are connected by fusing their ends together in the molding tool, to then be separated again from each succeeding tie after being used in the binding device.
On the other hand, the ties fused together at their ends serve merely as transport adjuncts in the feed and automatic positioning of fastening elements arranged in a row and are not utilized in the binding of the cable bundles.

Arrangement of fastening elements for holding bundles retained by cable ties


The present invention is directed to a system and method for emulating a serial small computer system interface (SAS) connection for direct attached serial advanced technology attachment (SATA) communication are disclosed. A system in accordance with the present invention includes a host controller. The host controller includes a physical interface for accepting at least one of a SAS connection or a direct attached SATA device. A common interface logic configured to receive SAS communications and SATA communications having a SAS emulated connection is included in the host controller. An emulation logic is communicatively coupled to the common interface logic. The emulation logic being configured to determine a value of a ConnectedSata signal based on the state of a SATA link state machine.

Data storage system controllers often implement devices employing various communication protocols. Typically, host controllers implementing serial SCSI devices may also support serial ATA devices as well. A dual protocol capability may allow for hybrid systems with increased transactional performance offered by SCSI based drives while permitting back-up redundancy from lower cost serial ATA drives. As a result, the host controller includes a physical connection interface for both serial SCSI and serial ATA as well as the individual circuitry associated with the communication protocols for the different standards. The inclusion of circuitry for both serial SCSI and serial ATA requires additional chipset space thus increasing die size during manufacture and the expense associated with having a dual physical connection/communication protocol system. Furthermore, the complexity of a dual circuit system increases the cost of the host controller. Additionally, with the inclusion of both serial SCSI and serial ATA circuitry, the integration of devices implementing these protocols occurs at a higher level logic than if only one type of device is implemented. As a result, the higher level circuitry is required to handle the integration of data which-in-turn may effect data transfer performance in comparison to a single protocol controller.
Serial SCSI implements connections during communication between the host/device (initiator/target). Connections include a serial SCSI protocol (SSP), SCSI management protocol (SMP) and serial ATA tunneled protocol (STP). In contrast, during serial ATA communication, the host and device do not establish a connection as is done with SAS communication.
Therefore, it would be desirable to provide a method and system for emulating SAS connection for utilization with SATA devices/communication.

Serial attached small computer system interface (SAS) connection emulation for direct attached serial advanced technology attachment (SATA)


A medical device attachable to the front of a conventional syringe and having a hub assembly selectively attachable to the syringe, a nose projecting forwardly from the hub assembly, a rearwardly biased needle retraction mechanism seated inside the nose, a retractable needle projecting forwardly of the nose, and a fluid flow path from the fluid chamber through the hub assembly, nose, needle retraction assembly and needle, wherein the needle is retracted into the nose and a retraction tube external to the syringe by rotating the syringe relative to the nose.

1. Field of the Invention
This invention relates to the use of conventional syringes in combination with a newly disclosed frontal attachment having a retractable needle. The invention relates more particularly to a medical device comprising in combination a needle, nose and hub assembly attachable to a conventional syringe preferably having a forwardly facing luer lock connector. The subject device has a needle retraction mechanism that is activated by rotating the syringe barrel relative to the nose of the device to retract the needle from a patient and propel it into the nose and a retraction tube that is part of the hub assembly.
2. Description of Related Art
Conventional syringes comprising a generally cylindrical barrel, a fixed needle projecting forwardly from the barrel, and a plunger slidably disposed inside the barrel through an opening in the rear of the barrel are well known. More recently, syringes have been made with a luer connector on the front of the barrel to which a needle hub is attachable to allow needles of different gauges or sizes to be used with a commonly configured barrel.
Even more recently, in an effort to control the spread of blood-borne pathogens and the incidence of contamination by contact with either exposed needles or bodily fluids, syringes having fixed or changeable needles have been designed to embody various "safety" elements. Such "safety" elements should desirably include a retractable needle, but many products marketed as having "safety" elements include, for example, covers or guards that are manually operated by medical personnel administering an injection to shield or cover the needle tip following removal of the needle from a patient.
Some previously disclosed needle retraction systems without changeable needles are activated either manually or automatically by application of a force upon completion of an injection to force the needle and needle tip back inside a retraction chamber. The only known syringe having a changeable, retractable needle does not have a conventional luer lock connection, and the retraction mechanism is activated by the application of a forwardly directed force to the plunger handle following removal of the needle from a patient, thereby exposing the needle and also exposing the user to the risk of needle-stick injury.
U.S. Pub. No. 2006/0155244 to Popov discloses a venipuncture device that rotates a port unit following needle retraction. The retraction chamber is disposed inside the medical device, is not part of the frontal attachment and remains stable while the port unit is moved rotationally relative to the retraction chamber following needle retraction. The frontal attachment disclosed there cannot be used with a generic luer lock syringe.
Although many advancements in syringe technology have been made in recent years, a frontal attachment device is needed that can be used with a standard syringe having a conventional luer lock connector, that offers the advantages of a changeable needle in combination with the advantages of a retractable needle providing sufficient retraction force to retract the needle while inserted into a patient, and that can be activated by the application of a rotational force to the syringe barrel while stabilizing the nose without applying a forwardly directed force to the plunger or the needle.

Frontal attachment device for syringe with rotationally activated retractable needle