A thermosetting composition is provided comprising:

The present invention relates to thermosetting (curable) compositions of one or more crosslinking agents and one or more epoxy functional polymers. The epoxy functional polymer is prepared by atom transfer radical polymerization, and has well defined polymer chain structure, molecular weight and molecular weight distribution. The present invention also relates to methods of coating a substrate, substrates coated by such methods, and color-plus-clear composite coating compositions.
Reducing the environmental impact of curable compositions, such as that associated with emissions into the air of volatile organic compounds during the application of curable coating compositions, has been an area of ongoing investigation and development in recent years. Accordingly, interest in high solids liquid coating compositions has been increasing, due in part to their comparatively lower volatile organic content (VOC), which significantly reduces air emissions during the application process.
Lower VOC coating compositions are particularly desirable in the automotive original equipment manufacture (OEM) market, due to the relatively large volume of coatings that are used. However, in addition to the requirement of lower VOC levels, automotive manufacturers have very strict performance requirements for the coatings that are used. For example, automotive OEM clear top coats are typically required to have a combination of good exterior durability, acid etch and water spot resistance, and excellent gloss and appearance.
Thermosetting coatings containing epoxy functional polymers have been developed in recent years for use as automotive OEM clear top coats. Such coating compositions typically comprise a crosslinking agent having at least two functional groups that are reactive with epoxides, and an epoxy functional polymer. The epoxy functional polymers used in such coating compositions are typically prepared by standard, i.e., non-living, radical polymerization methods, which provide little control over molecular weight, molecular weight distribution and polymer chain structure.
The physical properties, e.g., viscosity, of a given polymer can be directly related to its molecular weight. Higher molecular weights are typically associated with, for example, higher Tg values and viscosities. The physical properties of a polymer having a broad molecular weight distribution, e.g., having a polydispersity index (PDI) in excess of 2.5, can be characterized as an average of the individual physical properties of and indeterminate interactions between the various polymeric species that comprise it. As such, the physical properties of polymers having broad molecular weight distributions can be variable and hard to control.
The polymer chain structure, or architecture, of a polymer can be described as the sequence of monomer residues along the polymer back bone or chain. An epoxy functional copolymer prepared by standard radical polymerization techniques will contain a mixture of polymer molecules having varying individual epoxy equivalent weights and polymer chain structures. In such a copolymer, the epoxy functional groups are located randomly along the polymer chain. Moreover, the number of functional groups is not divided equally among the polymer molecules, such that some polymer molecules may actually be free of epoxy functionality. In a thermosetting composition, the formation of a three-dimensional crosslinked network is dependent on the functional equivalent weight as well as the architecture of the individual polymer molecules that comprise it. Polymer molecules having little or no reactive functionality (or having functional groups that are unlikely to participate in crosslinking reactions due to their locations along the polymer chain) will contribute little or nothing to the formation of the three-dimensional crosslinked network, resulting in decreased crosslink density and less than optimum physical properties of the finally formed polymerizate, e.g., a cured or thermoset coating.
The continued development of new and improved thermosetting compositions having lower VOC levels and a combination of favorable performance properties is desirable. In particular, it would be desirable to develop thermosetting compositions that comprise epoxy functional copolymers having well-defined molecular weights and polymer chain structure, and narrow molecular weight distributions, e.g., PDI values less than 2.5.
International patent publication WO 97/18247 and U.S. Pat. Nos. 5,763,548 and 5,789,487 describe a radical polymerization process referred to as atom transfer radical polymerization (ATRP). The ATRP process is described as a living radical polymerization that results in the formation of polymers having predictable molecular weight and molecular weight distribution. The ATRP process of these publications is also described as providing highly uniform products having controlled structure (i.e., controllable topology, composition, etc.). These patent publications also describe polymers prepared by ATRP, which are useful in a wide variety of applications, for example, with paints and coatings.
It would be desirable to develop thermosetting compositions that comprise epoxy functional copolymers prepared using atom transfer radical polymerization, thus having well-defined molecular weights and polymer chain structure, and narrow molecular weight distributions. Such compositions would have lower VOC levels due to lower viscosities, and a combination of favorable performance properties, particularly in coatings applications.
In accordance with the present invention, a thermosetting composition is provided comprising:
(a) a crosslinking agent having at least two functional groups that are reactive with epoxides; and
(b) a non-gelled, epoxy functional polymer prepared by atom transfer radical polymerization, in the presence of an initiator having at least one radically transferable group, and wherein the polymer contains at least one of the following polymer chain structures:
xe2x80x94{(M)pxe2x80x94(G)q}xxe2x80x94
or
xe2x80x94{(G)qxe2x80x94(M)p}xxe2x80x94
wherein M is a residue, that is free of epoxy functionality, of at least one ethylenically unsaturated radically polymerizable monomer; G is a residue, that has epoxy functionality, of at least one ethylenically unsaturated radically polymerizable monomer; p and q represent average numbers of residues occurring in a block of residues in each polymer chain structure; and p, q, and x are each independently selected for each structure such that the epoxy functional polymer has a number average molecular weight of at least 250.
Also provided by the present invention are methods of coating a substrate using compositions of the present invention, substrates coated by such methods, and color-plus-clear composite coating compositions.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as modified in all instances by the term xe2x80x9caboutxe2x80x9d.
As used herein, the term xe2x80x9cpolymerxe2x80x9d is meant to refer to both homopolymers, i.e., polymers made from a single monomer species, and copolymers, i.e., polymers made from two or more monomer species, as well as oligomers.
The epoxy functional polymer used in the composition of the present invention is a non-gelled polymer prepared by atom transfer radical polymerization, in the presence of an initiator having at least one radically transferable group. The polymer contains at least one of the following polymer chain structures:
xe2x80x94{(M)pxe2x80x94(G)q}xxe2x80x94xe2x80x83xe2x80x83(I)
or
xe2x80x94{(G)qxe2x80x94(M)p}xxe2x80x94xe2x80x83xe2x80x83(II)
where M is a residue, that is free of epoxy functionality, of at least one ethylenically unsaturated radically polymerizable monomer; G is a residue, that has epoxy functionality, of at least one ethylenically unsaturated radically polymerizable monomer; p and q represent average numbers of residues occurring in a block of residues in each polymer chain structure; and p, q, and x are each independently selected for each structure such that the epoxy functional polymer has a number average molecular weight (Mn) of at least 250, preferably at least 1000, and more preferably at least 2000. The epoxy functional polymer also typically has a M, of less than 16,000, preferably less than 10,000, and more preferably less than 5000. The Mn of the epoxy functional polymer may range between any combination of these values, inclusive of the recited values. Unless otherwise indicated, all molecular weights described in the specification and claims are determined by gel permeation chromatography using a polystyrene standard. Note that structures I and II define xe2x80x9cx segmentsxe2x80x9d within the polymer.
The subscripts p and q as shown in structures I and II represent average numbers of residues occurring in a block of residues in each polymer chain structure. Typically, p and q each independently have a value of 0 or more, preferably at least 1, and more preferably at least 5 for each of general polymer structures I and II. Also, subscripts p and q each independently have a value of typically less than 100, preferably less than 20, and more preferably less than 15 for each of general polymer structures I and II. The values of subscripts p and q may range between any combination of these values, inclusive of the recited values. Moreover, the sum of p and q is greater than zero within an x segment and q is greater than zero within at least one x segment in the polymer.
Typically, the subscript x as shown in structures I and II has a value of at least 1. Also, subscript x typically has a value of less than 100, preferably less than 50, and more preferably less than 10. The value of subscript x may range between any combination of these values, inclusive of the recited values. Moreover, when more than one of the structures I and/or II occur in a polymer molecule, x may have different values for each structure (as may p and q) allowing for a variety of polymer architectures, such as gradient copolymers.
The xe2x80x94(M)pxe2x80x94 portion of general structures I and II represents (1) a homoblock of a single type of M residue (that is p units long), (2) an alternating block of two types of M residues, (3) a polyblock of two or more types of M residues, or (4) a gradient block of two or more types of M residues. For purposes of illustration, when the M-block is prepared from, for example, 10 moles of methyl methacrylate, the xe2x80x94(M)pxe2x80x94 portion of structures I and II represents a homoblock of 10 residues of methyl methacrylate. In the case where the M-block is prepared from, for example, 5 moles of methyl methacrylate and 5 moles of butyl methacrylate, the xe2x80x94(M)pxe2x80x94 portion of general structures I and II typically represents, depending on the conditions of preparation, as is known to one of ordinary skill in the art: (a) a diblock of 5 residues of methyl methacrylate and 5 residues of butyl methacrylate having a total of 10 residues (i.e., p=10); (b) a diblock of 5 residues of butyl methacrylate and 5 residues of methyl methacrylate having a total of 10 residues; (c) an alternating block of methyl methacrylate and butyl methacrylate residues beginning with either a residue of methyl methacrylate or a residue of butyl methacrylate; and having a total of 10 residues; or (d) a gradient block of methyl methacrylate and butyl methacrylate residues beginning with either residues of methyl methacrylate or residues of butyl methacrylate having a total of 10 residues.
The xe2x80x94(G)qxe2x80x94 portions of polymer chain structures I and II may be described in a manner similar to that of the xe2x80x94(M)pxe2x80x94 portions.
The following are presented for the purpose of illustrating the various polymer architectures that are represented by general polymer chain structures I and II.
Homoblock Polymer Architecture:
When x is 1, p is 0 and q is 5, general polymer chain structure I represents a homoblock of 5 G residues, as more specifically depicted by the following general formula III.
xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94xe2x80x83xe2x80x83III
Diblock Copolymer Architecture:
When x is 1, p is 5 and q is 5, general polymer chain structure I represents a diblock of 5 M residues and 5 G residues as more specifically depicted by the following general formula IV.
xe2x80x94(M)xe2x80x94(M)xe2x80x94(M)xe2x80x94(M)xe2x80x94(M)xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94xe2x80x83xe2x80x83IV
Alternating Copolymer Architecture:
When x is greater than 1, for example, 5, and p and q are each 1 for each x-segment, polymer chain structure I represents an alternating block of M and G residues, as more specifically depicted by the following general formula V.
xe2x80x94(M)xe2x80x94(G)xe2x80x94(M)xe2x80x94(G)xe2x80x94(M)xe2x80x94(G)xe2x80x94(M)xe2x80x94(G)xe2x80x94(M)xe2x80x94(G)xe2x80x94xe2x80x83xe2x80x83V
Gradient Copolymer Architecture:
When x is greater than 1, for example, 4, and p and q are each independently within the range of, for example, 1 to 3, for each x-segment, polymer chain structure I represents a gradient block of M and G residues, as more specifically depicted by the following general formula VI.
xe2x80x94(M)xe2x80x94(M)xe2x80x94(M)xe2x80x94(G)xe2x80x94(M)xe2x80x94(M)xe2x80x94(G)xe2x80x94(G)xe2x80x94(M)xe2x80x94(G)xe2x80x94(G)xe2x80x94(M)xe2x80x94(G)xe2x80x94(G)xe2x80x94(G)xe2x80x94xe2x80x83xe2x80x83VI
Gradient copolymers can be prepared from two or more monomers by ATRP methods, and are generally described as having architecture that changes gradually and in a systematic and predictable manner along the polymer backbone. Gradient copolymers can be prepared by ATRP methods by (a) varying the ratio of monomers fed to the reaction medium during the course of the polymerization, (b) using a monomer feed containing monomers having different rates of polymerization, or (c) a combination of (a) and (b). Gradient copolymers are described in further detail on pages 72 through 78 of international patent publication WO 97/18247.
Residue M of general polymer chain structures I and II is derived from at least one ethylenically unsaturated radically polymerizable monomer. As used herein and in the claims, xe2x80x9cethylenically unsaturated radically polymerizable monomerxe2x80x9d and like terms are meant to include vinyl monomers, (meth)allylic monomers, olefins and other ethylenically unsaturated monomers that are radically polymerizable.
Classes of vinyl monomers from which M may be derived include, but are not limited to, (meth)acrylates, vinyl aromatic monomers, vinyl halides and vinyl esters of carboxylic acids. As used herein and in the claims, by xe2x80x9c(meth)acrylatexe2x80x9d and like terms is meant both methacrylates and acrylates. Preferably, residue M is derived from at least one of alkyl (meth)acrylates having from 1 to 20 carbon atoms in the alkyl group, vinyl aromatic monomers, vinyl halides, vinyl esters of carboxylic acids and olefins. Specific examples of alkyl (meth)acrylates having from 1 to 20 carbon atoms in the alkyl group from which residue M may be derived include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethyl cyclohexyl (meth)acrylate, and isobutyl (meth)acrylate.
Residue M may also be selected from monomers having more than one (meth)acrylate group, for example, (meth)acrylic anhydride and diethyleneglycol bis((meth)acrylate). Residue M may also be selected from alkyl (meth)acrylates containing radically transferable groups, which can act as branching monomers, for example, 2-(2-bromopropionoxy)ethyl acrylate.
Specific examples of vinyl aromatic monomers from which M may be derived include, but are not limited to, styrene, p-chloromethylstyrene, divinyl benzene, vinyl naphthalene and divinyl naphthalene. Vinyl halides from which M may be derived include, but are not limited to, vinyl chloride and vinylidene fluoride. Vinyl esters of carboxylic acids from which M may be derived include, but are not limited to, vinyl acetate, vinyl butyrate, vinyl benzoate, vinyl esters of VERSATIC Acid (VERSATIC Acid is a mixture of tertiary aliphatic carboxylic acids available from Shell Chemical Company), and the like.
As used herein and in the claims, by xe2x80x9colefinxe2x80x9d and like terms is meant unsaturated aliphatic hydrocarbons having one or more double bonds, obtained by cracking petroleum fractions. Specific examples of olefins from which M may be derived include, but are not limited to, propylene, 1-butene, 1,3-butadiene, isobutylene and di-isobutylene.
As used herein and in the claims, by xe2x80x9c(meth)allylic monomer(s)xe2x80x9d is meant monomers containing substituted and/or unsubstituted allylic functionality, i.e., one or more radicals represented by the following general formula VII,
xe2x80x83H2Cxe2x95x90C(R)xe2x80x94CH2xe2x80x94xe2x80x83xe2x80x83VII
wherein R is hydrogen, halogen or a C1 to C4 alkyl group. Most commonly, R is hydrogen or a methyl group. Examples of (meth)allylic monomers include, but are not limited to: (meth)allyl alcohol; (meth)allyl ethers, such as methyl (meth)allyl ether; (meth)allyl esters of carboxylic acids, such as (meth)allyl acetate; (meth)allyl benzoate; (meth)allyl n-butyrate; (meth)allyl esters of VERSATIC Acid; and the like.
Other ethylenically unsaturated radically polymerizable monomers from which M may be derived include, but are not limited to: cyclic anhydrides, e.g., maleic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride and itaconic anhydride; esters of acids that are unsaturated but do not have xcex1,xcex2-ethylenic unsaturation, e.g., methyl ester of undecylenic acid; and diesters of ethylenically unsaturated dibasic acids, e.g., diethyl maleate.
The monomer block designated as (G)q in the structures above may be derived from one type of monomer or a mixture of two or more monomers. As discussed above, such mixtures may be blocks of monomer residues or they may be alternating residues.
Residue G of general polymer chain structures I and II may be derived from monomers having epoxy functionality. Preferably residue G is derived from at least one of glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl(meth)acrylate, 2-(3,4-epoxycyclohexyl)ethyl(meth)acrylate and allyl glycidyl ether. In a particularly preferred embodiment of the present invention, residue G is derived from glycidyl methacrylate. Alternatively, epoxy functionality may be incorporated into the polymer by post-reaction, such as by preparing a hydroxyl or acid functional polymer and converting it to an epoxy functional polymer by reacting it with epichlorohydrin or a glycidyl ester.
Preferably, the polymer contains at least one of the following polymer chain structures:
xe2x80x83xcfx86xe2x80x94[{(M)pxe2x80x94(G)q}xxe2x80x94(M)rxe2x80x94T]zxe2x80x83xe2x80x83(VIII)
or
xcfx86xe2x80x94[{(G)qxe2x80x94(M)p}xxe2x80x94(G)sxe2x80x94T]zxe2x80x83xe2x80x83(IX)
where the subscripts r and s represent average numbers of residues occurring in the respective blocks of M and G residues. The xe2x80x94(M)rxe2x80x94 and xe2x80x94(G)sxe2x80x94 portions of general structures VIII and IX have meanings similar to those as previously described herein with regard to portions xe2x80x94(M)pxe2x80x94 and xe2x80x94(G)qxe2x80x94. The moiety xcfx86 is or is derived from a residue of the initiator free of the radically transferable group; p, q, and x are as defined above; z is at least 1; T is or is derived from the radically transferable group of the initiator; and the epoxy functional polymer has a polydispersity index of less than 2.5, preferably less than 2.0, more preferably less than 1.8, and even more preferably less than 1.5.
It should be understood that the structures VIII and IX can represent the polymer itself or, alternatively, each of the structures can comprise a terminal segment of the polymer. For example, when the polymer is by prepared by ATRP using an initiator having one radically transferable group and z is 1, either of the structures VIII and IX can represent an entire linear polymer. However, when the epoxy functional polymer is a star or other branched polymer, wherein some of the branches may not have epoxy functionality, general polymer chain structures VIII and IX represent a portion of the epoxy functional polymer.
For each of general polymer structures VIII and IX, the subscripts r and s each independently have a value of 0 or more. Subscripts r and s each independently have a value of typically less than 100, preferably less than 50, and more preferably less than 10, for each of general polymer structures VIII and IX. The values of r and s may each range between any combination of these values, inclusive of the recited values.
The epoxy functional polymer typically has an epoxy equivalent weight of at least 128 grams/equivalent, preferably at least 200 grams/equivalent. The epoxy equivalent weight of the polymer is also preferably less than 10,000 grams/equivalent, preferably less than 5000 grams/equivalent, and more preferably less than 1000 grams/equivalent. The epoxy equivalent weight of the epoxy functional polymer may range between any combination of these values, inclusive of the recited values. As used herein, epoxy functional equivalent weights are determined in accordance with ASTM D 1652.
As mentioned above, the epoxy functional polymer used in the thermosetting compositions of the present invention is prepared by atom transfer radical polymerization. The ATRP method is described as a xe2x80x9cliving polymerizatior.,xe2x80x9d i.e., a chain-growth polymerization that propagates with essentially no chain transfer and essentially no chain termination. The molecular weight of a polymer prepared by ATRP can be controlled by the stoichiometry of the reactants, i.e., the initial concentration of monomer(s) and initiator(s). In addition, ATRP also provides polymers having characteristics including, for example, narrow molecular weight distributions, e.g., PDI values less than 2.5, and well defined polymer chain structure, e.g., block copolymers and alternating copolymers.
The ATRP process can be described generally as comprising: polymerizing one or more radically polymerizable monomers in the presence of an initiation system; forming a polymer; and isolating the formed polymer. The initiation system comprises: an initiator having at least one radically transferable atom or group; a transition metal compound, i.e., a catalyst, which participates in a reversible redox cycle with the initiator; and a ligand, which coordinates with the transition metal compound. The ATRP process is described in further detail in international patent publication WO 97/18247 and U.S. Pat. Nos. 5,763,548 and 5,789,487.
In preparing epoxy functional polymers of the present invention, the initiator may be selected from the group consisting of linear or branched aliphatic compounds, cycloaliphatic compounds, aromatic compounds, polycyclic aromatic compounds, heterocyclic compounds, sulfonyl compounds, sulfenyl compounds, esters of carboxylic acids, polymeric compounds, and mixtures thereof, each having at least one radically transferable group, which is typically a halo group. The initiator may also be substituted with functional groups, e.g., epoxy groups. Additional useful initiators and the various radically transferable groups that may be associated with them are described on pages 42 through 45 of international patent publication WO 97/18247.
Polymeric compounds (including oligomeric compounds) having radically transferable groups may be used as initiators, and are herein referred to as xe2x80x9cmacroinitiators.xe2x80x9d Examples of macroinitiators include, but are not limited to, polystyrene prepared by cationic polymerization and having a terminal halide, e.g., chloride, and a polymer of 2-(2-bromopropionoxy)ethyl acrylate and one or more alkyl (meth)acrylates, e.g., butyl acrylate, prepares by conventional non-living radical polymerization. Macroinitiators can be used in the ATRP process to prepare graft polymers, such as grafted block copolymers and comb copolymers. A further discussion of macroinitiators is found in U.S. Pat. No. 5,789,487.
Preferably, the initiator may be selected from the group consisting of halomethane, methylenedihalide, haloform, carbon tetrahalide, methanesulfonyl halide, p-toluenesulfonyl halide, methanesulfenyl halide, p-toluenesulfenyl halide, 1-phenylethyl halide, 2-halopropionitrile, C1-C6-alkyl ester of 2-halo-C1-C6-carboxylic acid, p-halomethylstyrene, mono-hexakis(xcex1-halo-C1-C6-alkyl)benzene, diethyl-2-halo-2-methyl malonate, benzyl halide, ethyl 2-bromoisobutyrate and mixtures thereof. A particularly preferred initiator is diethyl-2-bromo-2-methyl malonate.
Catalysts that may be used in preparing epoxy functional polymers of the present invention, include any transition metal compound that can participate in a redox cycle with the initiator and the growing polymer chain. It is preferred that the transition metal compound not form direct carbon-metal bonds with the polymer chain. Transition metal catalysts useful in the present invention may be represented by the following general formula X,
TMn+Qnxe2x80x83xe2x80x83(X)
wherein TM is the transition metal, n is the formal charge on the transition metal having a value of from 0 to 7, and Q is a counterion or covalently bonded component. Examples of the transition metal (TM) include, but are not limited to, Cu, Au2+, Ag, Hg, Pd, Pt, Co, Mn, Ru, Mo, Nb, Fe, and Zn. Examples of Q include, but are not limited to, halogen, hydroxy, oxygen, C1-C6-alkoxy, cyano, cyanato, thiocyanato and azido. A preferred transition metal is Cu(I) and Q is preferably halogen, e.g., chloride. Accordingly, a preferred class of transition metal catalysts are the copper halides, e.g., Cu(I)Cl. It is also preferred that the transition metal catalyst contain a small amount, e.g., 1 mole percent, of a redox conjugate, for example, Cu(II)Cl2 when Cu(I)Cl is used. Additional catalysts useful in preparing the epoxy functional polymers of the present invention are described on pages 45 and 46 of international patent publication WO 97/18247. Redox conjugates are described on pages 27 through 33 of international patent publication WO 97/18247.
Ligands that may be used in preparing epoxy functional polymers of the present invention include, but are not limited to compounds having one or more nitrogen, oxygen, phosphorus and/or sulfur atoms, which can coordinate to the transition metal catalyst compound, e.g., through sigma and/or pi bonds. Classes of useful ligands, include but are not limited to: unsubstituted and substituted pyridines and bipyridines; porphyrins; cryptands; crown ethers; e.g., 18-crown-6; polyamines, e.g., ethylenediamine; glycols, e.g., alkylene glycols, such as ethylene glycol; carbon monoxide; and coordinating monomers, e.g., styrene, acrylonitrile and hydroxyalkyl(meth)acrylates. A preferred class of ligands are the substituted bipyridines, e.g., 4,4xe2x80x2-dialkyl-bipyridyls. Additional ligands that may be used in preparing epoxy functional polymers of the present invention are described on pages 46 through 53 of international patent publication WO 97/18247.
In preparing the epoxy functional polymers of the present invention the amounts and relative proportions of initiator, transition metal compound and ligand are those for which ATRP is most effectively performed. The amount of initiator used can vary widely and is typically present in the reaction medium in a concentration of from 10xe2x88x924 moles/liter (M) to 3 M, for example, from 10xe2x88x923 M to 10xe2x88x921 M. As the molecular weight of the epoxy functional polymer can be directly related to the relative concentrations of initiator and monomer(s), the molar ratio of initiator to monomer is an important factor in polymer preparation. The molar ratio of initiator to monomer is typically within the range of 10xe2x88x924:1 to 0.5:1, for example, 10xe2x88x923:1 to 5xc3x9710xe2x88x922:1.
In preparing the epoxy functional polymers of the present invention, the molar ratio of transition metal compound to initiator is typically in the range of 10xe2x88x924:1 to 10:1, for example, 0.1:1 to 5:1. The molar ratio of ligand to transition metal compound is typically within the range of 0.1:1 to 100:1, for example, 0.2:1 to 10:1.
Epoxy functional polymers useful in the thermosetting compositions of the present invention may be prepared in the absence of solvent, i.e., by means of a bulk polymerization process. Generally, the epoxy functional polymer is prepared in the presence of a solvent, typically water and/or an organic solvent. Classes of useful organic solvents include, but are not limited to, ethers, cyclic ethers, C5-C10 alkanes, C5-C8 cycloalkanes, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, amides, nitriles, sulfoxides, sulfones and mixtures thereof. Supercritical solvents, such as CO2, C1-C4 alkanes and fluorocarbons, may also be employed. A preferred class of solvents are the aromatics, particularly preferred examples of which are xylene and SOLVESSO 100, a blend of aromatic solvents available from Exxon Chemicals America. Additional solvents are described in further detail on pages 53 through 56 of international patent publication WO 97/18247.
The epoxy functional polymer is typically prepared at a reaction temperature within the range of 25xc2x0 C. to 140xc2x0 C., preferably from 50xc2x0 C. to 100xc2x0 C., and a pressure within the range of 1 to 100 atmospheres, typically at ambient pressure. The atom transfer radical polymerization is typically completed in less than 24 hours, e.g., between 1 and 8 hours.
Prior to use in the thermosetting compositions of the present invention, the ATRP transition metal catalyst and its associated ligand are typically separated or removed from the epoxy functional polymer. This, however, is not a requirement of the invention. Removal of the ATRP catalyst is achieved using known methods, including, for example, adding a catalyst leg binding agent to the a mixture of the polymer, solvent and catalyst, followed by filtering. Examples of suitable catalyst binding agents include, for example, alumina, silica, clay or a combination thereof. A mixture of the polymer, solvent and ATRP catalyst may be passed through a bed of catalyst binding agent. Alternatively, the ATRP catalyst may be oxidized in situ and retained in the epoxy functional polymer.
The epoxy functional polymer may be selected from the group consisting of linear polymers, branched polymers, hyperbranched polymers, star polymers, graft polymers and mixtures thereof. The form, or gross architecture, of the polymer can be controlled by the choice of initiator and monomers used in its preparation. Linear epoxy functional polymers may be prepared by using initiators having one or two radically transferable groups, e.g., diethyl-2-halo-2-methyl malonate and xcex1,xcex1xe2x80x2-dichloroxylene. Branched epoxy functional polymers may be prepared by using branching monomers, i.e., monomers containing radically transferable groups or more than one ethylenically unsaturated radically polymerizable group, e.g., 2-(2-bromopropionoxy)ethyl acrylate, p-chloromethylstyrene and diethyleneglycol bis(methacrylate). Hyperbranched epoxy functional polymers may be prepared by increasing the amount of branching monomer used.
Star epoxy functional polymers may be prepared using initiators having three or more radically transferable groups, e.g., hexakis(bromomethyl)benzene. As is known to those of ordinary skill in the art, star polymers may be prepared by core-arm or arm-core methods. In the core-arm method, the star polymer is prepared by polymerizing monomers in the presence of the polyfunctional initiator, e.g., hexakis(bromomethyl)benzene. Polymer chains, or arms, of similar composition and architecture grow out from the initiator core, in the core-arm method.
In the arm-core method, the arms are prepared separately from the core and optionally may have different compositions, architecture, molecular weight and PDI""s. The arms may have different epoxy equivalent weights, and some may be prepared without any epoxy functionality. After the preparation of the arms, they are attached to the core.
Epoxy functional polymers in the form of graft polymers may be prepared using a macroinitiator, as previously described herein. Graft, branched, hyperbranched and star polymers are described in further detail on pages 79 through 91 of international patent publication WO 97/18247.
The polydispersity index (PDI) of epoxy functional polymers useful in the present invention, is typically less than 2.5, more typically less than 2.0, and preferably less than 1.8, for example, 1.5. As used herein, and in the claims, xe2x80x9cpolydispersity indexxe2x80x9d is determined from the following equation: (the weight average molecular weight (Mw)/number average molecular weight (Mn)). A monodisperse polymer has a PDI of 1.0.
The symbol xcfx86 as shown in structures VIII and IX is or is derived from a residue of the initiator free of the radically transferable group; it is most often a sulfonyl group or a malonate. For example, if the epoxy functional polymer is initiated by benzyl bromide, xcfx86, or more specifically, xcfx86-, is a residue of the structure:
Also, xcfx86 may derived from the residue of the initiator. For example, when the polymer is initiated using epichlorohydrin, xcfx86,or more specifically, xcfx86-, is the 2,3-epoxy-propyl residue,
The 2,3-epoxy-propyl residue can then be converted to, for example, a 2,3-dihydroxypropyl residue. Derivations or conversions of the initiator residue are preferably performed at a point in the ATRP process when loss of epoxy functionality along the polymer backbone is minimal, for example, prior to incorporating a block of residues having epoxy functionality.
In general formulas VIII and IX, subscript z is equal to the number of epoxy functional polymer chains that are attached to xcfx86. Subscript z is at least 1 and may have a wide range of values. In the case of comb or graft polymers, wherein xcfx86 is a macroinitiator having several pendant radically transferable groups, z can have a value in excess of 10, for example 50, 100 or 1000. Typically, z is less than 10, preferably less than 6 and more preferably less than 5. In a preferred embodiment of the present invention, z is 1 or 2.
Symbol T of general formulas VIII and IX is or is derived from the radically transferable group of the initiator. For example, when the epoxy functional polymer is prepared in the presence of diethyl-2-bromo-2-methyl malonate, T may be the radically transferable bromo group.
The radically transferable group may optionally be (a) removed or (b) chemically converted to another moiety. In either of (a) or (b), the symbol T is considered herein to be derived from the radically transferable group of the initiator. The radically transferable group may be removed by substitution with a nucleophilic compound, e.g., an alkali metal alkoxylate. In the present invention, it is desirable that the method by which the radically transferable group is either removed or chemically converted also be relatively mild with regard to the epoxy functionality of the polymer. Many nucleophilic substitutions and hydrolysis reactions can result in loss of epoxy functionality from the polymer.
In a preferred embodiment of the present invention, the radically transferable group is a halogen and is removed by means of a mild dehalogenation reaction, which does not reduce the epoxy functionality of the polymer. The reaction is typically performed as a post-reaction after the polymer has been formed, and in the presence of at least an ATRP catalyst. Preferably, the dehalogenation post-reaction is performed in the presence of both an ATRP catalyst and its associated ligand.
The mild dehalogenation reaction is performed by contacting the halogen terminated epoxy functional polymer of the present invention with one or more ethylenically unsaturated compounds, which are not readily radically polymerizable under at least a portion of the spectrum of conditions under which atom transfer radical polymerizations are performed, hereinafter referred to as xe2x80x9climited radically polymerizable ethylenically unsaturated compoundsxe2x80x9d (LRPEU compound). As used herein, by xe2x80x9chalogen terminatedxe2x80x9d and similar terms is meant to be inclusive also of pendent halogens, e.g., as would be present in branched, comb and star polymers.
Not intending to be bound by any theory, it is believed, based on the evidence at hand, that the reaction between the halogen terminated epoxy functional polymer and one or more LRPEU compounds results in (1) removal of the terminal halogen group, and (2) the addition of at least one carbon-carbon double bond where the terminal carbon-halogen bond is broken. The dehalogenation reaction is typically conducted at a temperature in the range of 0xc2x0 C. to 200xc2x0 C., e.g., from 0xc2x0 C. to 160xc2x0 C., a pressure in the range of 0.1 to 100 atmospheres, e.g., from 0.1 to 50 atmospheres. The reaction is also typically performed in less than 24 hours, e.g., between 1 and 8 hours. While the LRPEU compound may be added in less than a stoichiometric amount, it is preferably added in at least a stoichiometric amount relative to the moles of terminal halogen present in the epoxy functional polymer. When added in excess of a stoichiometric amount, the LRPEU compound is typically present in an amount of no greater than 5 mole percent, e.g., 1 to 3 mole percent, in excess of the total moles of terminal halogen.
Limited radically polymerizable ethylenically unsaturated compounds useful for dehalogenating the epoxy functional polymer of the composition of the present invention under mild conditions include those represented by the following general formula XII.
In general formula XII, R1 and R2 can be the same or different organic groups such as: alkyl groups having from 1 to 4 carbon atoms; aryl groups; alkoxy groups; ester groups; alkyl sulfur groups; acyloxy groups; and nitrogen-containing alkyl groups where at least one of the R1 and R2 groups is an organo group while the other can be an organo group or hydrogen. For instance when one of R1 or R2 is an alkyl group, the other can be an alkyl, aryl, acyloxy, alkoxy, arenes, sulfur-containing alkyl group, or nitrogen-containing alkyl and/or nitrogen-containing aryl groups. The R3 groups can be the same or different groups selected from hydrogen or lower alkyl selected such that the reaction between the terminal halogen of the epoxy functional polymer and the LRPEU compound is not prevented. Also an R3 group can be joined to the R1 and/or the R2 groups to form a cyclic compound.
It is preferred that the LRPEU compound be free of halogen groups. Examples of suitable LRPEU compounds include, but are not limited to, 1,1-dimethylethylene, 1,1-diphenylethylene, isopropenyl acetate, alpha-methyl styrene, 1,1-dialkoxy olefin and mixtures thereof. Additional examples include dimethyl itaconate and diisobutene (2,4,4-trimethyl-1-pentene).
For purposes of illustration, the reaction between the halogen terminated epoxy functional polymer and LRPEU compound, e.g., alpha-methyl styrene, is summarized in the following general scheme 1.
In general scheme 1, P-X represents the halogen terminated epoxy functional polymer.
As indicated above, the epoxy functional polymer may have any of a number of polymer structures, selected from linear polymers, branched polymers, hyperbranched polymers, star polymers, gradient polymers, and graft polymers. Mixtures of one or more different types of these polymers may be used in the composition of the present invention.
The epoxy functional polymer may be used in the thermosetting composition of the present invention as a resinous binder or as an additive in combination with a separate resinous binder, which may be prepared by atom transfer radical polymerization or conventional polymerization methods. When used as an additive, the epoxy functional polymer as described herein may have low functionality (it may be monofunctional) and a correspondingly high equivalent weight. Alternatively, for other applications such as use as a reactive diluent, the additive may be highly functional with a correspondingly low equivalent weight.
The epoxy functional polymer is typically present in the thermosetting composition of the present invention in an amount of at least 0.5 percent by weight (when used as an additive), preferably at least 10 percent by weight (when used as a resinous binder), and more preferably at least 25 percent by weight, based on the total weight of resin solids of the thermosetting composition. The thermosetting composition also typically contains epoxy functional polymer present in an amount of less than 99.5 percent by weight, preferably less than 90 by weight, and more preferably less than 75 percent by weight, based on the total weight of resin solids of the thermosetting composition. The epoxy functional polymer may be present in the thermosetting composition of the present invention in an amount ranging between any combination of these values, inclusive of the recited values.
The thermosetting composition of the present invention further comprises a crosslinking agent having at least two functional groups that are reactive with epoxides. The parameter of at least two functional groups per molecule is also intended to encompass mixtures of crosslinking agents in which di-functional materials are mixed with tri- or higher functionality materials. Examples of suitable crosslinking agents include polyamines, polyamides and polycarboxylic acids, including polyanhydrides, and polyphenolic compounds.
Suitable polyamines and polyamides include amine and amide functional addition polymers and oligomers typically used in film-forming compositions such as acrylic and vinyl polymers and dicyanodiamide.
Suitable polycarboxylic acids include dodecanedioic acid, azelaic acid, adipic acid, 1,6-hexanedioic acid, succinic acid, pimelic acid, sebacic acid, maleic acid, citric acid, itaconic acid, aconitic acid, carboxylic acid-terminated polyesters, half-esters formed from reacting an acid anhydride with a polyol, and mixtures thereof.
Also among the polycarboxylic acids which may be used are carboxylic acid group-containing polymers such as acrylic polymers, polyesters, and polyurethanes; oligomers such as ester group-containing oligomers; as well as fatty diacids.
Acid-functional acrylic crosslinkers may be made by copolymerizing methacrylic acid and/or acrylic acid monomers with other ethylenically unsaturated copolymerizable monomers, using techniques known to those skilled in the art. Alternatively, acid-functional acrylics can be prepared from hydroxy-functional acrylics reacted with cyclic anhydrides using conventional techniques.
Additional polycarboxylic acid crosslinking agents are ester group-containing oligomers. Examples include half-esters formed by reacting polyols and 1,2-acid cyclic anhydrides such as the half ester formed by reacting pentaerythritol and methylhexahydrophthalic anhydride, or acid functional polyesters derived from polyols and polyacids or anhydrides. The half-esters are of relatively low molecular weight and are quite reactive with epoxy functionality enabling the formulation of high solids fluid compositions while maintaining outstanding properties such as gloss and distinctness of image.
Such ester group-containing oligomers and the preparation thereof are described in U.S. Pat. No. 5,384,367, column 8, line 41 to column 11, line 10.
Suitable polyanhydrides include addition polymers and oligomers typically used in film-forming compositions such as acrylic and vinyl polymers.
Examples of polyanhydrides suitable for use as curing agents in the curable compositions of the present invention include those described in U.S. Pat. No. 4,798,746 at column 10, lines 16-50; and in U.S. Pat. No. 4,732,790 at column 3, lines 41-57.
The crosslinking agent is typically present in the thermosetting compositions of the present invention in an amount of at least 10 percent by weight, preferably at least 25 percent by weight, based on total resin solids weight of the composition. The crosslinking agent is also typically present in the composition in an amount of less than 90 percent by weight, preferably less than 75 percent by weight, based on total resin solids weight of the composition. The amount of crosslinking agent present in the thermosetting composition of the present invention may range between any combination of these values, inclusive of the recited values.
The equivalent ratio of epoxide groups in the polymer to reactive functional groups in the crosslinking agent is typically within the range of 1:0.5 to 1:1.5, preferably 1:0.8 to 1:1.2.
Usually the thermosetting composition will also preferably contain catalysts to accelerate the cure of the crosslinking agent with reactive groups on the polymer(s). When the crosslinking agent is acid functional, basic esterification catalysts are typically used and the thermosetting composition of the present invention may comprise one or two packages. To form one-package compositions, the thermosetting composition of the present invention is substantially free of basic esterification catalyst. In a preferred embodiment, the composition of the present invention has no or only small amounts of basic esterification catalyst such that the composition is stable for a time sufficient to allow formulation of the composition as a single component; i. e., one-package, composition.
To form multi-package or multi-component compositions in which the epoxy functional polymer and acid functional crosslinking agent are present in separate packages and combined shortly before application, an esterification catalyst to promote cure can be included in the composition. A number of such catalysts are known in the art. These catalysts include basic materials such as secondary amine catalysts, for example, piperidine; tertiary amine catalysts such as methyl dicocoamine, N,N-dimethyldodecylamine, pyridine, and N,N-dimethylaniline; ammonium compounds, including tetrabutylammonium bromide, tetrabutylammonium hydroxide, and tetrabutylammonium acetate; phosphonium compounds, including ethyltriphenylphosphonium acetate and tetrabutyl phosphonium bromide; and other ammonium and phosphonium salts.
Suitable catalysts for polyamine crosslinking agents include tertiary amines as are known in the art.
The catalyst is usually present in an amount of about 0.05 to about 5.0 percent by weight, preferably about 0.25 to about 2.0 percent by weight, based on the total weight of resin solids in the thermosetting composition.
The thermosetting composition of the present invention is preferably used as a film-forming (coating) composition, and may contain adjunct ingredients conventionally used in such compositions. Optional ingredients such as, for example, plasticizers, surfactants, thixotropic agents, anti-gassing agents, organic cosolvents, flow controllers, anti-oxidants, UV light absorbers and similar additives conventional in the art may be included in the composition. These ingredients are typically present at up to about 40% by weight based on the total weight of resin solids.
The thermosetting composition of the present invention is typically a liquid and may be waterborne, but is usually solventborne. Suitable solvent carriers include the various esters, ethers, and aromatic solvents, including mixtures thereof, that are known in the art of coating formulation. The composition typically has a total solids content of about 40 to about 80 percent by weight.
The thermosetting composition of the present invention may contain color pigments conventionally used in surface coatings and may be used as a monocoat; that is, a pigmented coating. Suitable color pigments include, for example, inorganic pigments such as titanium dioxide, iron oxides, chromium oxide, lead chromate, and carbon black, and organic pigments such as phthalocyanine blue and phthalocyanine green. Mixtures of the above mentioned pigments may also be used. Suitable metallic pigments include in particular aluminum flake, copper bronze flake and metal oxide coated mica, nickel flakes, tin flakes, and mixtures thereof.
In general, the pigment is incorporated into the coating composition in amounts up to about 80 percent by weight based on the total weight of coating solids. The metallic pigment is employed in amounts of about 0.5 to about 25 percent by weight based on the total weight of coating solids.
As stated above, the thermosetting compositions of the present invention may be used in a method of coating a substrate comprising applying a thermosetting composition to the substrate, coalescing the thermosetting composition over the substrate in the form of a substantially continuous film, and curing the thermosetting composition.
The compositions can be applied to various substrates to which they adhere including wood, metals, glass, and plastic.
The compositions can be applied by conventional means including brushing, dipping, flow coating, spraying and the like, but they are most often applied by spraying. The usual spray techniques and equipment for air spraying and electrostatic spraying and either manual or automatic methods can be used.
After application of the composition to the substrate, the composition is allowed to coalesce to form a substantially continuous film on the substrate. Typically, the film thickness will be about 0.01 to about 5 mils (about 0.254 to about 127 microns), preferably about 0.1 to about 2 mils (about 2.54 to about 50.8 microns) in thickness. The film is formed on the surface of the substrate by driving solvent, i.e., organic solvent and/or water, out of the film by heating or by an air drying period. Preferably, the heating will only be for a short period of time, sufficient to ensure that any subsequently applied coatings can be applied to the film without dissolving the composition. Suitable drying conditions will depend on the particular composition, but in general a drying time of from about 1 to 5 minutes at a temperature of about 68-250xc2x0 F. (20-121xc2x0 C.) will be adequate. More than one coat of the composition may be applied to develop the optimum appearance. Between coats the previously applied coat may be flashed; that is, exposed to ambient conditions for about 1 to 20 minutes.
The film-forming composition of the present invention is preferably used as the clear coat layer in a multi-component composite coating composition such as a xe2x80x9ccolor-plus-clearxe2x80x9d coating system, which includes at least one pigmented or colored base coat and at least one clear topcoat. In this embodiment, the clear film-forming composition may include the thermosetting composition of the present invention.
The film-forming composition of the base coat in the color-plus-clear system can be any of the compositions useful in coatings applications, particularly automotive applications. The film-forming composition of the base coat comprises a resinous binder and a pigment to act as the colorant. Particularly useful resinous binders are acrylic polymers, polyesters, including alkyds, and polyurethanes. Polymers prepared using atom transfer radical polymerization may also be used as resinous binders in the base coat.
The base coat compositions may be solventborne or waterborne. Waterborne base coats in color-plus-clear compositions are disclosed in U.S. Pat. No. 4,403,003, and the resinous compositions used in preparing these base coats can be used in the practice of this invention. Also, waterborne polyurethanes such as those prepared in accordance with U.S. Pat. No. 4,147,679 can be used as the resinous binder in the base coat. Further, waterborne coatings such as those described in U.S. Pat. 5,071,904 can be used as the base coat.
The base coat contains pigments to give it color. Suitable pigments include those discussed above. In general, the pigment is incorporated into the coating composition in amounts of about 1 to 80 percent by weight based on weight of coating solids. Metallic pigment is employed in amounts of about 0.5 to 25 percent by weight based on weight of coating solids.
If desired, the base coat composition may contain additional materials well known in the art of formulated surface coatings, including those discussed above. These materials can constitute up to 40 percent by weight of the total weight of the coating composition.
The base coating compositions can be applied to various substrates to which they adhere by conventional means, but they are most often applied by spraying. The usual spray techniques and equipment for air spraying and electrostatic spraying and either manual or automatic methods can be used.
During application of the base coat composition to the substrate, a film of the base coat is formed on the substrate. Typically, the base coat thickness will be about 0.01 to 5 mils (0.254 to 127 microns), preferably 0.1 to 2 mils (2.54 to 50.8 microns) in thickness.
After application of the base coat to the substrate, a film is formed on the surface of the substrate by driving solvent out of the base coat film by heating or by an air drying period, sufficient to ensure that the clear coat can be applied to the base coat without the former dissolving the base coat composition, yet insufficient to fully cure the base coat. More than one base coat and multiple clear coats may be applied to develop the optimum appearance. Usually between coats, the previously applied coat is flashed.
The clear topcoat composition may be applied to the base coated substrate by any conventional coating technique such as brushing, spraying, dipping or flowing, but spray applications are preferred because of superior gloss. Any of the known spraying techniques may be employed such as compressed air spraying, electrostatic spraying and either manual or automatic methods.
After application of the clear coat composition to the base coat, the coated substrate may be heated to cure the coating layer(s). In the curing operation, solvents are driven off and the film-forming materials in the composition are crosslinked. The heating or curing operation is usually carried out at a temperature in the range of from 160-350xc2x0 F. (71-177xc2x0 C.) but if needed, lower or higher temperatures may be used as necessary to activate crosslinking mechanisms.
The invention will be further described by reference to the following examples. Unless otherwise indicated, all parts are by weight.

Thermosetting compositions containing epoxy-functional polymers prepared using atom transfer radical

Abstract: (b) a non-gelled, epoxy functional polymer prepared by atom transfer radical polymerization, in the presence of an initiator having at least one radically transferable group. The polymer contains at least one of the following polymer chain structures:

Abstract: or

Abstract: wherein M is a residue, that is free of epoxy functionality, of at least one ethylenically unsaturated radically polymerizable monomer; G is a residue, that has epoxy functionality, of at least one ethylenically unsaturated radically polymerizable monomer; p and q represent average numbers of residues occurring in a block of residues in each polymer chain structure; and p, q, and x are each independently selected for each structure such that the epoxy functional polymer has a number average molecular weight of at least 250. Also provided by the present invention are methods of coating a substrate using compositions of the present invention and substrates coated by such methods, as well as color-plus-clear composite coatings.


A semiconductor device comprises a BGA substrate having one principal plane furnished with a large number of solder balls, the solder balls constituting a ball grid array; a semiconductor chip mounted on another principal plane of the BGA substrate, the semiconductor chip being electrically connected to the BGA substrate by metal wires; and chip capacitors mounted on the semiconductor chip to reduce power source noise.

1. Field of the Invention
The present invention relates to a semiconductor device and, more particularly, to a semiconductor device which handles signals at high speed, and to a semiconductor device which has capacitors for reducing power source noise.
2. Description of the Background Art
FIG. 22 is a perspective view for describing a typical structure of a conventional semiconductor device of the above type. FIG. 23 is a cross-sectional view for describing the semiconductor device shown in FIG. 22. In these FIGS. 22 and 23, reference numeral 1 indicates a system substrate on which to mount components. Reference numeral 2 indicates a BGA (ball grid array) substrate mounted on the system substrate 1. As is well known, numerous solder balls 3 are interposed between the BGA substrate 2 and a principal plane of the system substrate 1 to keep the two substrates fixed and electrically connected. Reference numeral 4 indicates a semiconductor chip mounted on the BGA substrate 2. As shown in FIG. 23, bumps 5 are interposed between the semiconductor chip 4 and a principal plane of the BGA substrate 2 to have the chip and substrate fixed and electrically connected.
Reference numeral 6 indicates chip capacitors mounted on the system substrate 1 and BGA substrate 2. A large number of chip capacitors 6 are interposed connectively between power supply terminals (not shown) on a semiconductor device that handles signals at high speed; these chip capacitors 6 are provided to reduce power source noise and thereby to stabilize voltage levels of the power source and ground.
Given the above constitution, one disadvantage of the conventional semiconductor device is that the chip capacitors 6 are located away from the semiconductor chip 4. Therefore, as the speed of signals, which are handled by the semiconductor device, is higher, the inductance between the semiconductor chip 4 and the chip capacitors 6 becomes higher. The growing inductance progressively reduces the immunity of the chip to power source noise.
Another disadvantage is that the flow of high-speed signals generates electromagnetic waves from the semiconductor chip 4, its package, or its mounting substrate. When reaching nearby electronic equipment, the electromagnetic waves can induce electric currents therein by electromagnetic induction, triggering a malfunction at times.
Further, semiconductor chips are mounted on the system substrate basically in a two-dimensional manner. This leads to another problem: semiconductor chips, as they are designed to become ever higher in performance, incorporate a growing number of I/O terminals which translate into an ever-greater external size. On that extended component scale, differences in thermal expansion coefficient between the semiconductor chip 4 and the system substrate 1 can result in a warped substrate or dislodged terminals. Here, "dislodged terminals" means that the accuracy of location of terminals is changed for worse.
Therefore, above-mentioned flaws make it difficult to mount semiconductor chips 4 precisely on the system substrate 1. The yield rate of the chip 4 thus tends to decline and the reliability of mounting worsens.
The BGA type semiconductor device is at its limit of fabrication when coming to measure about 40 mm per side. When large-sized devices carry numerous terminals, they may adopt a pin grid array structure. The pin grid array structure, however, requires installing a socket between the semiconductor chip and the mounting substrate, which raises fabrication costs.
The BGA type semiconductor device is the to be at its limit of fabrication when coming to measure about 40 mm per side. When large-sized devices carry numerous terminals, they may adopt a pin grid array structure. The pin grid array structure, however, requires installing a socket between the semiconductor chip and the mounting substrate, which raises fabrication costs.
Multi-chip modules (MCM) have different external shapes and different numbers of terminals from one system to another. Such diversities make it difficult for the modules to share sockets and substrates between them. This is another factor pushing up the costs involved.
Another problem with the BGA type is that the module or chip is not receptive to what is known as rework. That is, considerable difficulties are experienced when a semiconductor device or MCM is dismounted from the system substrate for repair or for replacement with a new one having higher performance and the repaired or a replacement device is again mounted onto the system substrate.
Furthermore, the heat dissipating structure of the BGA type leaves much to be desired in terms of performance and production costs.

Semiconductor device having capacitors for reducing power source noise


The present invention includes improvements to a rotating frame trap which makes the trap more species specific and provides a more humane kill of targeted species. These improvements include means of trigger tensioning, latch adjustment for hair trigger firing, a recessed trigger design, multiple latches, a square notch latch coupled with a flat jaw wire, a pan attachement on a trigger, and a one directional firing mechanism.

1. Field of the Invention
The present invention is a more species specific and humane animal trap. The animal trap is actuated by triggering mechanism improvements.
2. Description of Prior Art
In searching prior art, the following patents were discovered:
U.S. Pat. No. 1,210,253; Dec. 26, 1916; Ahlenus
U.S. Pat. No. 1,970,672; Aug. 21, 1934; Prestenback
U.S. Pat. No. 2,228,808; Jan. 14, 1941; Keppel
U.S. Pat. No. 2,459,580; Jan. 18, 1949; Oleen
U.S. Pat. No. 2,496,393; Feb. 7, 1950; Hayden
U.S. Pat. No. 2,564,811; Aug. 21, 1951; Mau
U.S. Pat. No. 2,577,182; Dec. 4, 1951; Clark
U.S. Pat. No. 2,701,428; Feb. 8, 1955; Mau
U.S. Pat. No. 2,947,107; Aug. 2, 1960; Lehn
U.S. Pat. No. 3,010,245; Nov. 28, 1961; Conibear
U.S. Pat. No. 3,106,036; Oct. 8, 1963; Lehn
U.S. Pat. No. 3,146,545, Sept. 1, 1964; Frost
U.S. Pat. No. 3,335,517; Aug. 15, 1967; Montgomery et al
U.S. Pat. No. 3,421,251; Jan. 14, 1969; Hofmeister
U.S. Pat. No. 3,426,471; Feb. 11, 1969; Lehn
U.S. Pat. No. 3,760,531; Sept. 25, 1973; Conibear
U.S. Pat. No. 3,762,094; Oct. 2, 1973; Conibear
U.S. Pat. No. 3,816,955; Jun. 18, 1974; Conibear
U.S. Pat. No. 3,924,347; Dec. 9, 1975; Conibear
U.S. Pat. No. 3,991,509; Nov. 16, 1976; Frost
U.S. Pat. No. 4,117,623; Oct. 3, 1978; Conibear
U.S. Pat. No. 4,128,961; Dec. 12, 1978 Conibear
U.S. Pat. No. 4,406,082; Sept. 27, 1983; Askins et al;
U.S. Pat. No. 4,250,654; Feb. 17, 1981; Souza et al;
U.S. Pat. No. 5,579,602; Dec. 3, 1996; Maw
This seems to be a crowded art. The goals of the above inventors included more humane and reliable kills with lighter weight low cost mechanisms. Many an animal has suffered needlessly when caught in such a manner that death came slowly. Often an animal would twist off or bite off a leg to escape. Many a pet dog has been caught in a trap meant for a wild animal. Hunters have accidently stepped into traps and been injured, even suffering, on occasion, a cruel death from exposure while trapped.
In the prior art, as an animal goes through a trap known as a rotating frame trap, it hits a trigger wire which rotates a trigger bracket which elevates a latch which holds the trap jaws apart. As the latch elevates, the trap jaws are rotated by at least one spring, snapping shut on the animal. The intent is to humanely kill a specific specie of animal. Rotating frame traps are designed with a specific jaw spread and spring strength along with other factors for a specific size animal. Far too often, something smaller than the appropriate size is killed by the trap. Examples of unintended kills include rare otters, Atlantic salmon, baby alligators, squirrels, chipmunks, grouse, quail, and song birds. Even when the appropriate sized target specie is caught in a prior art rotating frame trap, it often is caught in a non-lethal area of the body because of excess free travel or slop in the trap's firing mechanism.
Also, in the prior art, the latching mechanisms tend to wear and become less reliable than the present invention.
Rotating frame traps are often used in buckets and in cavities in the ground in order to avoid non-target catches.
As will be seen in the subsequent description, the present invention includes improvements over the prior art that insure a more reliable, humane, and species specific kill than is currently available.

Species specific tensioned hair triggered firing mechanism for animal traps


The present invention relates to a process of liquefying starch wherein the liquefaction step is carried out at pH less than 6. It also relates to the use of antioxidants.

Grains such as corn have long been used as a source of starch. One of the classic methods of separating the starch and then using it in other industrial processes is the wet-milling process. This method is a highly specific and integrated system developed to separate the major components of a grain kernel as completely as possible (see Stanley A. Watson, Starch: Chemistry & Technology, Vol. II, Industrial Aspects, Academic press, New York, 1967, pp 30-51). A final granular starch slurry coming out of the wet milling process can be used in a variety of industrial processes.
One of the most important processes is the conversion of starch to high fructose syrup. In practice, this conversion involves four major steps; namely liquefaction of granular starch slurry, saccharification of the liquified starch into dextrose, purification, and then isomerization of dextrose into fructose. The most common grain used in this process is corn in the production of high fructose corn syrup (see N. H. Aschengreen, et al; Starch Vol. 31, pp 64-66 (1979)). During the four step conversion to fructose, it is currently necessary that the granular starch slurry is varied widely in pH. The pH of the slurry coming out of the commercial wet-milling operation is about 4, then raised to a pH of from 6-6.4, and calcium is added along with enzyme. For saccharification of the starch the ph is lowered to 4.3-4.5 and for the final isomerization the pH is increased back to about 7.8. The result of these wide shifts in pH is a high ion exchange requirement to desalt the syrup during and after processing. Furthermore, high pH causes byproduct formation, sugar breakdown, color formation, and an overall decrease in product yield. These factors add millions of dollars annually to the cost of high fructose syrup production. The industrial isomerization process is currently very efficient due to current processing techniques and the short processing time. Accordingly, it would be useful if the liquefaction step could be carried out at lower pH's to obviate the need for a pH shift in commercial processes. It is possible to perform liquefaction at pH's less than 6 (see e.g. U.S. Pat. No. 4,376,824); however, the liquefaction is sometimes unexplainably incomplete and so has limited commercial utility. The antioxidant bisulfite has been used in the past as a component of starch slurry that is added during steeping operations to control pH and the nature of the fermentation. It is normally removed with the steep liquor.
Another source of starch is from the dry milling process. In the dry milling process the grain is ground and liquefaction can be carried on with or without separation of individual components of the kernel into grits, cornmeal or flour (see e.g. Corn: Chemistry & Technology by Alexander, K. , 1987, Chap. 11, Corn Dry Milling Productions and Applications). In addition to uses as in a variety of food and feed stuffs, he grain can also be used in the conversion of starch to alcohol. This process involves two steps to convert the milled grain or fractions therefrom into alcohol: liquefaction of the starch in the dry products after addition of water, and most generally a combined or simultaneous saccharification of the starch into glucose and fermentation of the glucose into alcohol.
The natural pH of the starch slurry of about 5 is adjusted upward with alkali or carbonate to a pH of 6.2-6.4 for liquefaction. After liquefaction the pH is adjusted downward by addition of acid or "backset" from previous fermentations. There are disadvantages to use of "backset" such as introduction of microbial contaminants into the fermentation.
The utility of the process of the invention is to reduce the need for pH adjustment on the up side and down side.

Liquefaction of granular starch slurries using an antioxidant with alpha amylase


A communications system, a communication management system and method are disclosed. Distribution information is distributed to communication terminal devices to which communication lines are connected. And a privilege is assigned to a user of the communication terminal device to which the distribution information is distributed.

1. Field of the Invention
The present invention relates to a communications system, a communication management system and method, and more particularly, to a communication system, a communications management system and method for distributing an advertisement during a telephone conversation.
2. Description of the Related Art
Conventionally, for example, a telephone for domestic use, etc. and a portable telephone terminal through a common line is connected to a specific line assigned by a common carrier, and simultaneously assigned a phone number corresponding to the line by a user making a contract for subscription with the common carrier.
Then, the user can receive a call from another subscriber through the common carrier by the phone number specified, or can issue a call to another subscriber through the common carrier by specifying the phone number of the another subscriber.
The rate for issuing and receiving calls is normally charged to a call issuing user, and the amount set based on the usage (time, day-of-week, telephone conversation time length, the address of a receiver, etc.) of the user is charged to the user.
Therefore, since the telephone rate is charged to the user as the predetermined amount based on the use of the issuing user, the longer the user communicates, the larger amount is charged to the user.

Communication system, communication management system and method


A rechargeable battery includes a housing having at least two cells and a cover which closes the housing. The cover includes a lower part which is coupled to the housing, an upper part which is arranged at a distance from the lower part and closes the lower part forming a seal, and labyrinth-like outlet channels provided between the lower part and the upper part for acid deposition. The lower part is cut through in the area of the upper part adjacent to the outlet channels. The cells in the cut-through areas are separated from one another in a liquid-tight manner by cell separating wall sections which are adjacent to the upper part, and which are closed by the upper part.

The present invention relates to a rechargeable battery (e.g., a lead-acid battery for use in vehicle starting, lighting, and ignition applications, etc.).
EP 0 523 273 B1 describes a rechargeable battery with a plastic housing in which two or more cells are arranged. Normally, there are 6 cells. The cover comprises a lower part, which is fitted to the housing such that it is liquid-tight and gastight, having in each case one filling and monitoring opening per cell, which can be closed by a sealing plug. An upper part is fitted to the lower part at a distance from the lower part, with labyrinth-like cavities for acid deposition being formed on the channel walls of each cell between the lower part and the upper part. Gas and liquid can flow through the filling and monitoring openings in the lower part, past the sealing plug, into the cavities. In order to dissipate the gases which are produced during operation of the lead-acid rechargeable battery, the degassing system which is formed by the cavities is provided with at least one degassing opening, which has ignition protection in the form of a flame trap valve.
EP 0 570 703 B1 describes a similar rechargeable battery, whose housing is likewise completely closed by the lower part and in which an upper part is arranged at a distance from the lower part, and a gas collection area for acid deposition is formed between the lower part and the upper part. Once again, the sealing plug extends down into the plane of the lower part. A gas outlet point is provided in the area of the sealing plug in the plane of the lower part, and is of such a size that, in the event of brief tilting up to 180° C., no more acid can emerge from the gas area of the respective cell, than is held by the cavity associated with it.
U.S. Pat. No. 5,843,593 discloses a leak-proof battery cover for an energy storage battery, which has a labyrinth formed by passages between each cell valve and an atmospheric valve. The cavities, which are in the form of a labyrinth, are designed such that a portion of each path of the labyrinth is always kept above the level reached by the electrolyte in the associated cell when the battery is tilted onto any of its sides, or is rotated through 90° from its upright position. This labyrinth arrangement prevents electrolyte from reaching the atmospheric valve and from emerging from the battery.
It would be advantageous to provide an improved rechargeable battery which has a battery cover which can be produced at a lower price and in a relatively efficient manner. It would also be advantageous to provide a rechargeable battery having a battery cover in which return flow of electrolyte which has been collected in the cavity into the cell is improved. It would also be advantageous to provide a rechargeable battery and cover in which the risk of static discharging in the cover is reduced. It would be advantageous to provide a battery having a cover that includes any one or more of these or other advantageous features.


An adapter plate for removably coupling an actuator arm end with a load beam and a transducer head. The adapter plate can be installed with a reliable, verifiable pressure, and removed easily without damage for rework or repair of the transducer head. The adapter plate includes a plate surface for coupling with a load beam, a latch hook formed on a first edge, and a coupling hook formed on a second, opposite edge. The coupling hook includes a notch formed centrally therein and extending inward toward the plate surface. The actuator arm end includes a grooved edge with a V-shaped groove formed therein and a latching edge opposite the grooved edge. A tapered pin is inserted between the notch in the coupling hook and the V-shaped groove so that the plate surface is pressured against the portion of the actuator arm end proximate thereto. For a multidisk system in which an actuator arm assembly includes multiple actuator arms, two adapter plates can be installed on one actuator arm, one on each side, and either of the adapter plates can be removed and re-installed without affecting the other adapter plate.

1. Field of the Invention
The present invention relates to arm assemblies for disk drives. More specifically, the present invention relates to an adapter for coupling an actuator arm with a transducer head.
2. Description of Related Art
Actuator arm assemblies are utilized within disk drive units for positioning a transducer head to read and write data in selected sections of a magnetic storage disk. One or more actuator arms form a part of the actuator arm assembly. Each actuator arm is coupled to a transducer head. The entire arm assembly is pivotable so that each head moves over the surface of its respective disk.
Some disk drive units have multiple magnetic disks in a standard configuration. In these disk drive units, the arm assembly includes a plurality of actuator arms positioned proximate to the stacked disks. Each of the actuator arms is coupled with a transducer head for reading and writing data. Each head contacts its disk with a load pressure provided by a load beam that connects the head with one of the actuator arms. To connect a load beam with an actuator arm, an adapter plate is often used. The load beam is spot welded to the adapter plate, which is fastened to the actuator arm end. A conventional method of fastening the adapter plate to the actuator arm is termed a "ball staking" method.
The ball staking method requires that the adapter plate have a hole formed therein with a sleeve extending therefrom. First, the extended sleeve is inserted in the actuator arm, specifically into a hole formed near the end of the actuator arm. Then, a ball is pressed through the hole in the adapter plate sleeve to deform the sleeve and generate an interference fit between the sleeve and the actuator arm end, thereby affixing the adapter plate to the actuator arm. To generate the required tightness of the interference fit, additional balls having progressively larger diameters may be pushed through. This process can be difficult and time consuming, which can increase manufacturing costs.
The ball staking process is particularly difficult in multiple disk systems, in which at least one actuator arm is positioned between two disks. Each of the two sides of an "in-between" arm has an adapter plate attached to a transducer head, and both of these adapter plates have sleeves that are affixed in the same hole in the actuator arm. If the actuator arm is thick, a reasonably good fit could be provided even if both sleeves have the same diameter. In that instance, both sleeves can be deformed against the hole without overlapping. However, fast, high performance actuator arms are thin to reduce weight, and the two sleeves necessarily overlap. This requires that the inner diameter of a first sleeve fits closely within the outer diameter of a second sleeve. This requires that the inner diameter of a first sleeve fits closely within the outer diameter of a second sleeve. Production of the overlapping configuration is difficult and time consuming, and requires very tight tolerances, particularly between inner and outer diameters of both sleeves and the hole.
In addition to manufacturing difficulties, the ball staking method has other drawbacks. If the adapter plate must be removed from the arm after the ball has been inserted and pressed into place, the only way is by forcible removal which could damage the adapter plate or the actuator arm. This problem is particularly acute when two adapter plates are affixed by overlapping sleeves into the same hole: damage to one or both adapter plates is likely. As a result of this problem, a certain percentage of magnetic head assemblies (defined as the adapter plate, load beam, and head) will be scrapped.
Another problem with the ball staking process is difficulty verifying proper assembly during manufacture. The adapter plate must have a sufficiently tight interference fit. However, it is very difficult to determine if the sides of the extended sleeve are tightly pressed against the hole within the actuator arm and that the plate itself is tightly pressed against the actuator arm end. If adapter plate is not affixed tightly, then undesirable mechanical resonances could be produced, which would result in a substantial reduction in performance.
It would be an advantage to provide an adapter plate coupling for an actuator arm that could easily be coupled to the actuator arm and easily removed therefrom. It would be a further advantage if the adapter plate could be installed on an actuator arm with a predictable pressure during the manufacturing process.

Adapter plate for coupling a head to an actuator arm in a disk drive assembly


Disclosed is a LGA socket connector including an insulative housing (2), a stiffener (3), a clip (4), and a lever (5) defining thereof a driving portion (50) and a locking portion (52) linked thereto. The stiffener is configured to grasp a periphery of the housing. The clip and the locking portion of the lever are essentially pivotally moved about longitudinal ends of the housing respectively, but with the driving portion disposed adjacent one transverse side of the housing. At least one of the clip and the stiffener is provided with a recessed region (300) adjacent said transverse side of the housing, thereby preventing the whole connector from becoming inclined when the connector is horizontally locked and placed on the printed circuit board.

1. Field of the Invention
The present invention relates to an electrical connector, especially to an LGA socket connector for connecting a CPU chip and a printed circuit board.
2. Background of the Invention
Various types of conventional electrical connectors are known for electrically connecting an IC package, such as a CPU, with a circuit board, such as a printed circuit board (PCB).
One of the widely-known electrical connectors is a land grid array (LGA) socket connector, particularly utilized for electrically connecting the CPU with the PCB. Typically, the LGA socket connector includes an insulative housing with a plurality of terminals assembled therein, a stiffener generally defining an opening to grasp a periphery of the housing, a clip and a lever respectively disposed adjacent two ends of the housing to jointly press the CPU chip onto the housing so as to make electrically connection between the CPU chip and the LGA socket.
In general, the housing, the stiffener, the clip each have a symmetrical configuration except for the lever. More specifically, the level, generally formed of a heavy metal, is composed of a locking portion and a driving portion linked to the locking portion. When the LGA socket is in a horizontally locked position, the driving portion is positioned beside one side of the clip, while the locking portion of the lever is disposed adjacent one end of the housing and in opposed relationship with the clip. As such, a center of gravity of the connector tends to be at a position biased towards the driving portion of the lever, thereby causing positional misalignment between a geometry center of the connector and the center of gravity of the connector.
When the LGA socket is horizontally locked and placed on the printed circuit board, the LGA socket becomes inclined with respect to the circuit board due to such positional misalignment between the geometry center and the gravity center of the connector. Coplanarity of the solder balls on the connector along a mounting interface is thus influenced by potential variations in sizes of respective solder balls, when the inclined connector is attached to the printed circuit board by solder balls melt at a high temperature. This will often result in electrical connection failure at a certain area between the inclined connector and the printed circuit board.
In view of the above, it is strongly desired to provide a new LGA socket connector, which overcomes the above-mentioned disadvantages.


Techniques utilising Time Scale Modification (TSM) of signals are described. The signal is analysed and divided into frames of similar signal types. Techniques specific to the signal type are then applied to the frames thereby optimising the modification process. The method of the present invention enables TSM of different audio signal parts to be realized using different methods, and a system for effecting said method is also described.

Time-scale modification (TSM) of a signal refers to compression or expansion of the time scale of that signal. Within speech signals, the TSM of the speech signal expands or compresses the time scale of the speech, while preserving the identity of the speaker (pitch, format structure). As such, it is typically explored for purposes where alteration of the pronunciation speed is desired. Such applications of TSM include test-to-speech synthesis, foreign language learning and film/soundtrack post synchronisation.
Many techniques for fulfilling the need for high quality TSM of speech signals are known and examples of such techniques are described in E. Moulines, J. Laroche, "Non parametric techniques for pitch scale and time scale modification of speech". In Speech Communication (Netherlands) Vol 16, No. 2 p175-205 1995.
Another potential application of TSM techniques is speech coding which, however, is much less reported. Within this application, the basic intention is to compress the time scale of a speech signal prior to coding, reducing the number of speech samples that need to be encoded, and to expand it by a reciprocal factor after decoding, to reinstate the original timescale. This concept is illustrated in FIG. 1. Since the time-scale compressed speech remains a valid speech signal, it can be processed by an arbitrary speech coder. For example, speech coding at 6 kbit/s could now be realised with a 8 kbit/s coder, preceeded by 25% time-scale compression and succeeded by 33% time-scale expansion.
The use of TSM in this context has been explored in the past, and fairly good results were claimed using several TSM methods and speech coders [1]-[3]. Recently, improvements have been made both to TSM and speech coding techniques, where these two have mostly been studied independently from each other.
As detailed in Moulines and Laroche, as referenced above, one widely used TSM algorithm is synchronised overlap-add (SOLA), which is an example of a waveform approach algorithm. Since its introduction [4], SOLA has evolved into a widely used algorithm for TSM of speech. Being a correlation method, it is also applicable to speech produced by multiple speakers or corrupted by background noise, and to some extent to music.
With SOLA, an input speech signal s is analysed as a sequence of N-samples long overlapping frames xi (i=0, . . . , m), consecutively delayed by a fixed analysis period of Sa, samples (Sa<N) The starting idea is that s can be compressed or expanded by outputting these frames while now successively shifting them by a synthesis period Ss, which is chosen such that Ss<Sa, respectively Ss>Sa (Ss<N). The overlapping segments would be first weighted by two amplitude complementary functions then added up, which is a suitable way of waveform averaging. FIG. 2 illustrates such an overlap-add expansion technique. The upper part shows the location of the consecutive frames in the input signal. The middle part demonstrates how these frames would be re-positioned during the synthesis, employing in this case two halves of a Hanning window for the weighting. Finally, the resulting time-scale expanded signal is shown in the lower part.
The actual synchronisation mechanism of SOLA consists of additionally shifting each xi during the synthesis, to yield similarity of the overlapping waveforms. Explicitly, a frame xi will now start contributing to the output signal at position iSs+ki, where ki is found such that the normalised cross-correlation given by Equation 1 is maximal for k=ki.
                                          R            i                                          [            k            ]                          =                                                            ∑                                  j                  =                  0                                                  L                  -                  1                                                                                s                    ~                                                                          [                                                                  iS                        s                                            +                      k                      +                      j                                        ]                                                  ·                                  s                                                        [                                                                  iS                        a                                            +                      j                                        ]                                                                                (                                                      ∑                                          j                      =                      0                                                              L                      -                      1                                                                                s                        2                                                                                [                                                                              iS                            a                                                    +                          j                                                ]                                                              ·                                                                  ∑                                                  j                          =                          0                                                                          L                          -                          1                                                                                s                            ~                                                    2                                                                                [                                                                                iS                              s                                                        +                            k                            +                            j                                                    ]                                                                                )                                            1                /                2                                                                    (                          0              ≤              k              ≤                              N                /                2                                      )                                              (Equation  1)
In this equation, {tilde over (s)} denotes the output signal while L denotes the length of the overlap corresponding to a particular lag k in the given range [1]. Having found ki, the synchronisation parameters, the overlapping signals are averaged as before. With a large number of frames the ratio of the output and input signal length will approach the value Ss/Sa, hence defining the scale factor α.
When SOLA compression is cascaded with the reciprocal SOLA expansion, several artefacts are typically introduced into the output speech, such as reverberation, artificial tonality and occasional degradation of transients.
The reverberation is associated with voiced speech, and can be attributed to waveform averaging. Both compression and the succeeding expansion average similar segments. However, similarity is measured locally, implying that the expansion does not necessarily insert additional waveform in the region where it was "missing". This results in waveform smoothing, possibly even introducing new local periodicity. Furthermore, frame positioning during expansion is designed to re-use same segments, in order to create additional waveform. This introduces correlation in unvoiced speech, which is often perceived as an artificial "tonality".
Artefacts also occur in speech transients, i.e. regions of voicing transition, which usually exhibit an abrupt alteration of the signal energy level. As the scale factor increases, so does the distance between 'iSa' and 'iSs' which may impede alignment of similar parts of a transient for averaging. Hence, overlapping distinct parts of a transient causes its "smearing", endangering proper perception of its strength and timing.
In [5], [6], it was reported that a companded speech signal of a good quality can be achieved by employing the ki's that are obtained during SOLA compression. So, quite opposite to what is done by SOLA, the N-samples long frames {circumflex over (x)}i would now be excised from the compressed signal {tilde over (s)} at time instants iSs+ki and re-positioned at the original time instants iSa (while averaging the overlapping samples similar as before). The maximal cost of transmitting/storing all ki's is given by Equation 2, where Ts, is the speech sampling period and ┌ ┐ represents the operation of rounding towards the nearest-higher integer.
                              BR          k                =                              (                                          1                                                      S                    a                                    ·                                      T                    s                                                                                frames                sec                                      )                    ·                      (                                          ⌈                                                      log                    2                                                                          (                                          N                      2                                        )                                                  ⌉                                                          bits                frame                                      )                                              (Equation  2)
It has also been reported that exclusion of transients from high (i.e. >30%) SOLA compression or expansion yields improved speech quality. [7]
It will be appreciated therefore that presently several techniques and approaches exist that can successfully (e.g. giving good quality) be employed for compressing or expanding the time-scale of signals. Although described specifically with reference to speech signals, it will be appreciated that this description is of an exemplary embodiment of a signal type and the problems associated with speech signals are also applicable to other signal types. When used for coding purposes, where the time-scale compression is followed by time-scale expansion (time-scale companding), the performance of prior art techniques degrade considerably. The best performance for speech signals is generally obtained from time-domain methods, among which SOLA is widely used, but problems still exist using these methods, some of which have been identified above. There is, therefore, a need to provide an improved method and system for time scale modifying a signal in a manner specific to the components making up that signal.


The present invention provides particulate tadalafil having a particle size of about 200 to about 600 microns and a process for controlling the particle size of tadalafil.

(6R-trans)-6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-pyrazino[1′,2′:1,6]pyrido[3,4-b]indole-1,4-dione (tadalafil) having the formula

is a potent and selective inhibitor of the cyclic guanosine monophosphate (cGMP)—specific phosphodiesterase enzyme PDE5. The inhibition of PDE5 increases the amount of cGMP, resulting in smooth muscle relaxation and increased blood flow. Tadalafil is therefore currently used in the treatment of male erectile dysfunction.
The solid state physical properties of an active pharmaceutical ingredient (API), such as tadalafil, can be very important in formulating a drug substance and can have profound effects on the ease and reproducibility of formulation. Particle size, for example, may effect the flowability and mixability of a drug substance. Small particles are also filtered and washed more slowly during isolation processes, and thus may increase the time and expense of manufacturing a drug formulation.
U.S. Pat. No. 5,859,006 discloses the synthesis of tadalafil. U.S. Pat. No. 6,821,975 describes the synthesis of tadalafil wherein 90% of the particles have a particle size of less than about 40 microns and a pharmaceutical composition containing this particle size.
There is a need in the art for tadalafil having a large particle size and for a process for the preparation thereof.

Tadalafil having a large particle size and a process for preparation thereof