A capped poly(phenylene ether) resin composition is formed from (1) a poly(phenylene ether) compound (PPE) in which at least a portion, preferably substantially all of the hydroxyl groups have been reacted with a compound containing ethylenic unsaturation (carbon-carbon double bonds) which is further reactive with unsaturated monomers (reactively endcapped PPE) and (2) a curable unsaturated monomer composition. The composition optionally contains a polymerization catalyst; a flame-retardant compound; and fibrous reinforcement. The composition can be cured to form a laminate, and clad with copper to form a circuit board.

None.
Not applicable.
The present invention is related to polymerizable compositions with excellent thermal and dielectric properties suited for applications such as molding, laminating, encapsulation, coating or potting. A desired application of the present invention is in molding compositions where excellent dielectric and thermal properties, solvent resistance and low coefficients of thermal expansion are required. Another desired application is in laminating products that are useful for composites and dielectrics as for example in printed circuit boards. Further, the present invention relates to a process for making thermoset polymer resins and laminates, and to products characterized by excellent dielectric and thermal properties that can be made to exhibit excellent solvent resistance and flame resistance. More particularly, the present invention relates to reactively end capped poly(phenylene ether) compounds and to their cure with certain unsaturated compounds for synthesizing resins ideally adapted for impregnating fibrous reinforcement in the manufacture of circuit boards.
Thermoset molding compositions known in the art, are generally thermosetting resins containing inorganic fillers and/or fibers. Upon heating these materials initially exhibit viscosities low enough to allow for melt processing and molding of an article from the filled thermoset monomer composition. Upon further heating the thermosetting monomers react and cure to form hard resins with high modulus.
Metal-clad boards, particularly such boards for use in fabricating printed circuits, are also well-known in the art. The simplest of such boards generally comprises a resinous plastic (polymeric) substrate to which is bonded at least one thin sheet (foil) of an electrically conductive material, preferably copper. The resinous plastic substrate can be clad with the metal foil on one or both sides, depending upon the desired use, and can be rigid or flexible depending upon the composition of the resinous plastic substrate, the choice of reinforcement (if any), and the intended use of the board.
A number of polyphenylene ether compositions having favorable dielectric properties and utility in circuit board manufacture are known. However, due to deficiencies in one or more properties, many such compositions have not attained wide commercial use. Specifically, while polyphenylene ethers exhibit excellent dielectric properties, deficiencies often are found in areas such as, inter alia, solvent resistance, flammability, solderability, and resistance to high temperatures. Moreover, times required for curing such compositions typically are too long for effective manufacture of circuit boards in large volume.
In addition to excellent dielectric properties, resinous compositions to be used for printed circuit board manufacture should be highly flame-retardant. A V-1 rating, as determined by Underwriters Laboratories test procedure UL-94, is universally required, with V-0 usually being preferred. The V-0 rating requires a flame-out time (FOT) of not more than 10 seconds in any trial and a cumulative FOT of not more than 50 seconds for five samples. As a practical matter, purchasers often mandate a maximum cumulative FOT of 35 seconds.
The fabricated board should not lose substantial weight and its surface should not be appreciably marred by contact with methylene chloride, a solvent commonly used for cleaning. Since conductive connections with the printed circuit typically are made by soldering, the board must be solder-resistant as evidenced by the lowest possible percent increase in thickness (Z-axis expansion) when exposed to liquid solder at 288xc2x0 C. In addition to all these properties of the cured material, a relatively short curing time is highly desirable. In preparing rigid metal-clad boards, it is common to form individual lamina, commonly called prepregs, by formulating a resinous binder composition made from epoxy, modified styrene, or the like. A liquid resin or solvent solution of the resin is placed impregnated into continuous webs of reinforcement and then dried and or partially cured in a vertical or horizontal treating tower or oven. Normally, the resin is partially cured or B-staged after exiting the treater tower or oven. The copper foil, optionally coated with an adhesive, is placed on one side of the prepreg and subjected to heating under pressure to effect a bond between the metal foil and the substrate. Multiple prepregs can be used in forming a single composite board.
Additionally, multilayer printed wiring boards will have a number of interposed laminae and copper sheets.
Pressing of the boards can be effected in a press by placing the foil/substrate structure between the platens and closing the press, or a continuous belt can be used. The curing cycle in the press will depend upon the nature and thickness of the laminate, the time and temperature of the cycle being those required to cure the substrate, and the bonding adhesive layer, if present. Sufficient pressure is required to effect adequate flow of the adhesive and/or substrate resins in order to wet-out and bond adequately. The pressure must be sufficient to prevent blistering which is due to the release of gases resulting either from retained volatiles in the substrate or adhesive layers, or resulting from by-products of the curing process.
Heretofore, Fox (U.S. Pat. No. 3,356,761) describes blends of high molecular weight, uncapped PPE (molecular weight 10,000 and preferably 50,000) with a liquid unsaturated vinyl monomer selected from the group consisting of styrenics, divinylbenzene, vinylpyridines, and alkylated and halogenated derivatives useful for film and fiber applications. Fox does not teach the advantages of capped PPE and said blends of capped PPE with allylic monomers, blend thereof, or blends of allylic monomers with styrenic monomers. Further he does not teach the advantages of alkylated styrenes, such a t-butyl styrene, in enhancing the thermal performance of the blend. He also does not demonstrate the significant thermal advantages of using a butylated styrene.
Wright, et al. (U.S. Pat. No. 3,557,045) disclose a thermosetting resin composition comprising (i) a polymerizable material containing a carbon-carbon double bonds, at least 5% of which is a liquid monomer, (ii) a poly(phenylene ether) resin, and (iii) a radical initiator. In particular the Wright, et al. teach compositions comprising a diallyl phthalate prepolymer, a poly(phenylene ether) resin, and a radical initiator, in which the composition is described as having improved electrical and mechanical properties.
Wright, et al. (U.S. Pat. No. 3,637,578) disclose a thermosetting resin composition comprising (i) a mixture of a liquid monomer containing carbon-carbon double bonds in an amount of at least 5% and having boiling point of 70xc2x0 C. or higher with a reactive polyester resin, (ii) a poly(phenylene ether) resin, and (iii) a radical initiator. It is described that the thermosetting resin composition can be cured to obtain a thermoset resin having improved electrical and mechanical properties. Examples 3-2 and 3-4 of this Wright, et al. patent disclose compositions comprising a poly(phenylene ether) resin, a polyester resin, triallyl cyanurate, and diallyl phthalate. The poly(phenylene ether) content of the composition is 20% and the balance is comprised of crosslinking components (i.e. polyester resin, triallylcyanurate, and diallyl phthalate).
Wright, et al. (U.S. Pat. No. 3,936,414) describe flame retardant compositions comprising (i) 10-50 parts by weight of a polyunsaturated monomer, (ii) 5-30 parts by weight of a polychlorinated or polybrominated aromatic hydrocarbon having a molecular weight of at least 200 and a chlorine or bromine content of at least 50% by weight, (iii) 20-60 parts by weight of a poly(phenylene ether), (iv) 0-30 parts by weight of a polyunsaturated polymer having unsaturated carbon-carbon bonds, and (v) 2-10 parts by weight of a peroxide. Examples of polyunsaturated monomers include triallylcyanurate and triallylisocyanurate.
The aforementioned U.S. Pat. Nos. 3,557,045, 3,637,578, 3,936,414 do not teach the advantages of reactively capped polyphenylene ether, the advantages of low molecular weight reactively endcapped polyphenylene ethers and blends thereof with of diallylphthalate or styrenics with allylated cyanurates.
Penco in U.S. Pat. No. 5,171,761 describes a composition comprising 1) A polyphenylene ether (PPE) deriving from the (co)polymerization of one or more substituted phenols by oxidative coupling; 2) At least one mono-unsaturated monomer compound able to (co)polymerize in the presence of radical initiators; 3) Optionally, at least one polyunsaturated monomer compound able to (co)polymerize in the presence of radical initiators; 4) At least one radical polymerization initiator; 5) Possibly at least one (co)polymer with elastomeric characteristics; 6) Usual additives, stabilizers, accelerators and flame retardant agents. It is well known that oxidative polymerization produces polyphenylene ethers with phenolic endgroups. Thus Penco teaches blends of hydroxyl terminated PPEs, or uncapped PPE, with vinyl monomer compositions. He teaches uncapped PPO having degrees of polymerization greater than 10 (number average molecular weight of approximately 1,200. But he teaches intrinsic viscosities of 0.54 dl/g. Further Penco teaches compositions comprising vinyl monomers such as styrenes and acrylics. He does not teach allylic monomers or blends of allylic monomers and styrenic monomers. They use styrenic and a divinylbenzene. He also does not demonstrat the significant thermal advantages of using a butylated stytrene.
The aforementioned U.S. Pat. Nos. 3,557,045, 3,637,578, 3,936,414 do not teach the advantages of reactively end-capped polyphenylene ether, the advantages of low molecular weight reactively endcapped polyphenylene ethers and blends thereof with of diallylphthalate or styrenics with allylated cyanurates. They also do not teach the thermal advantages of using a butylated stytrenes.
Katayose, et al. (U.S. Pat. No. 5,218,030) describes the use of (i) a poly(phenylene ether) containing pendant allyl or propargyl groups, (ii) triallylcyanurate or triallylisocyanurate, and optionally (iii) a flame retardant, or (iv) an antimony-containing auxiliary flame retardant. The poly(phenylene ether) compounds resins disclosed are uncapped poly(phenylene) ethers bearing terminal hydrogen groups.
Katayose, et al. (U.S. Pat. No. 5,352,745) disclose compositions with improved solvent resistance comprising a high molecular weight functionalized poly(phenylene ether) resin (=0.30xe2x88x920.56 IV PPE) produced through reactive extrusion of poly(phenylene ether) with, maleic anhydride. Formulation of (i) the reaction product of poly(phenylene ether) (PPE) with an unsaturated acid or acid anhydride with, (ii) triallylcyanurate or triallylisocyanurate, (iii) a brominated epoxy resin, (iv) novolac resins, and (v) a cure catalyst, produced flame retardant and solvent resistant resins useful in the production of printed circuit boards. Katayose, et al. show that a portion of the amino functionalized end groups contain capping residues. The skilled artisan would recognize that such end groups would comprise less than 10% of the hydroxyl end groups and would not be sufficient to significantly accelerate the cure rate of an allylic thermoset.
Tracy, et al. (U.S. Pat. No. 5,834,565) describe blends of low molecular weight poly(phenylene ether) compounds in thermosetting matrices such as epoxy cyanate ester and vinyl thermosets. These thermosetting compositions exhibit improved processability over analogous compositions containing high molecular weight poly(phenylene ether) compounds; however, capped poly(phenylene ether) resins are not taught or suggested by these references.
The aforementioned patents do not teach advantages of reactively end-capped polyphenylene ethers, like methacrylate capped poly(phenylene ether) and blends thereof with of vinyl monomers such as diallylphthalate or styrenics with allylated cyanurates. They also do not teach the thermal advantages of using a butylated stytrenes.
Percec, in U.S. Pat. Nos. 4,562,243, 4,663,402, 4,665,137, 4,701,514, 4,871,816, 5,091,480, describes the preparation of low molecular weight (number average molecular weight=1,000xe2x88x9210,000) cross-linkable polyphenylene ethers containing vinylbenzyl ethers and methacrylate end groups as thermosettable resins. However, blends of these polymers with vinyl monomers to produce thermosetting resins are not taught. In one of the these patents blends of reactively encapped PPO with vinyl monomers to form comb-copolymers is described, however such compositions are not thermosetting and would therefore would not be useful in printed circuit board or many thermoset molding applications. Further thermosetting blends of said resins with diallylphthalate or styrenics, such as brominated or butylated styrenics and blends thereof with allylated cyanurates are not taught.
None of the foregoing art recognizes the benefits of reactively endcapped poly(phenylene ether) compounds, e.g., methacrylate endcapped poly(phenylene ether) compounds in blends of vinyl monomer compositions to form easily processable thermosetting compositions. In particular blends with specific vinyl monomer compositions, such as those described herein, for thermosetting applications such as printed circuit boards or molding compositions. Inorganic reinforced compositions, including those comprising specific glass reinforcements with excellent dielectric properties are also not described.
The capped poly(phenylene ether) resin composition comprises (1) a poly(phenylene ether) compound (PPE) in which at least a portion, preferably substantially all of the hydroxyl groups have been reacted with a compound containing ethylenic unsaturation (carbon-carbon double bonds) which is further reactive with unsaturated monomers (reactively endcapped PPE) and (2) a curable unsaturated monomer composition. The compositions of the invention have enhanced compatibility between the PPE and the curable unsaturated monomer composition when the compositions are at least partially cured. Enhanced compatibility includes, for example, enhanced dispersion of the PPE and reduced phase separation. Laminates of the compositions that have been at least partially cured, including copper clad laminates have highly desirable physical and dielectric properties.
In a preferred embodiment, the inventive composition comprises a reactively endcapped PPE having an Mn less than 10,000. It is further desirable that the endcap group is a methacrylate group which may be derived by reaction of a methacrylate containing compound and a poly(phenylene ether). The curable unsaturated monomer composition comprises a monomer or monomers selected from the group consisting of (a) a compound or compounds containing one polymerizable carbon-carbon double bond (monofunctional unsaturated compound) and (b) a compound or compounds containing greater than one polymerizable carbon-carbon double bond (polyfunctional unsaturated compound). For printed circuit board applications it is useful if at least one of the unsaturated monomers contains bromine or phosphorus.
Such composition optionally also may contain a polymerization catalyst; a flame-retardant compound; and fibrous reinforcement.
A further embodiment of this invention particularly useful for printed circuit boards is a composition comprising a methacrylate capped poly(phenylene ether), a brominated styrene compound, and an unsaturated monomer composition which may further include other additives such as, for example, a fibrous reinforcement.
The inventive composition may be used to impregnate fibrous reinforcement clad with copper to form an electrical circuit boards offering excellent dielectric and thermal properties, and accelerated rates of polymerization in formation of the PPE compositions. Moreover, such PPE compositions also can be made flame-retardant.
The present invention relates to curable compositions comprising (1) a poly(phenylene ether) compound (PPE) in which all of the hydroxyl groups have been reacted with a compound containing ethylenic unsaturation which is further reactive with vinyl monomers (reactively endcapped PPE) and (2) a curable unsaturated monomer composition.
For processing considerations, it is desirable that the number average molecular weight of the reactively endcapped PPE is less than 10,000. It is further desirable that the endcap is a methacrylate group which may be derived by reaction of a methacrylate containing compound and a PPE resin. The curable unsaturated monomer composition comprises a monomer or monomers selected from the group consisting of (a) a compound or compounds containing one polymerizable carbon-carbon double bond and (b) a compound or compounds containing greater than one polymerizable carbon-carbon double bond. These materials are useful in a number of thermoset applications including, for example, adhesives, encapsulation, structural laminates, potting and casting compounds, extrudable thermosetting resins, printed circuit boards, and other applications in which low dielectric constant, dissipation factor, and/or good thermal properties are required. For printed circuit board applications the disclosed composition is highly useful if at least one of the unsaturated monomers contains bromine or phosphorus for achieving flame retardancy.
The reactively endcapped PPE compounds include compounds derived by reacting any of the known PPE compounds containing phenolic hydroxyl residues at a concentration of greater than about 5 ppm with a reactive capping agent. Such uncapped PPE compounds are described in a variety of patents and publications such as, for example, in U.S. Pat. Nos. 5,352,745, 5,213,886, and 5,834,565, the disclosures of which are expressly incorporated herein by reference.
The preferred reactively capped PPE compounds include those containing recurring units of structure 3. Most preferable poly(phenylene ether) compounds are of general structure, 1:
Qxe2x80x94(Jxe2x80x94K)yxe2x80x83xe2x80x831
wherein Q is the residuum of a phenol, including polyfunctional phenols, and includes radicals of the following structure, 2:
wherein, for structure 2, X is hydrogen, C1-100 alkyl, aryl, and mixed alkyl-aryl hydrocarbons, or such hydrocarbon groups containing a substituent selected from the group consisting of carboxylic acid, aldehyde, alcohol, and amino radicals. X also may be sulfur, sulfonyl, sulfuryl, oxygen, or other such bridging group having a valency of 2 to result in various bis- or higher polyphenols. R1-4 independently may be hydrogen, C1-100 alkyl, aryl, mixed alkyl-aryl hydrocarbons, and the like; y and n independently range from about 1-100, preferably about 1-3, and most preferably about 1-2; and in one embodiment, y and n are the same; and J comprises recurring units of the following structure, 3:
wherein, for structure 3, R5-8 independently may be hydrogen, alkyl, alkenyl, alkynoyl, aryl, mixed alkyl-aryl hydrocarbons, or such groups also containing a substituent selected from the group consisting of carboxylic acid, aldehyde, alcohol, and amino functionality (e.g., amide or imide group), and m ranges from 1-200, and K has the following structure:
wherein Z is
and wherein R9-11 are independently a hydrogen or C1-100 alkyl or aryl or mixed alkyl or aryl group. Preferably, R9-10 are hydrogen and R11 is methyl.
Preferred reactively capped PPEs are low molecular weight PPEs with a number average molecular weight ranging from between about 250 to 10,000 g/mol. Desirably, the PPE contains low levels of amine containing end groups derived from well known catalyst side reactions. It is preferable to remove such amine containing end groups prior to reactively capping the PPE. Such materials may be prepared by processing the uncapped PPE at temperatures about 150xc2x0 C. to about 350xc2x0 C. followed by capping. Prior to capping, the low molecular weight polyphenylene ethers employed herein may be prepared from PPE typically having a number average molecular weights in the range of about 15,000-25,000.
Such preparation of a low molecular weight PPE composition can be accomplished by reacting the PPE with an oxidizing agent such as, for example, a peroxide or a quinone, with or without a phenol (including bisphenols). Another procedure is to obtain a low molecular weight PPE by oxidative coupling as described above to produce resins of less than 3,000 number average molecular weight which are isolated, preferably, by a direct isolation method. Direct isolation is a process in which the PPE resin is isolated from the solvent used in polymerization by heating under reduced pressure. However, even such low molecular weight resins can optionally be functionalized with a peroxide or a peroxide and a phenol to achieve even lower molecular weight resins.
A capping catalyst, is often employed in the generation of the reactively capped PPE. Examples of such compounds include those known to the art that are capable of catalyzing condensation of phenols with the capping agents described below. Useful materials are basic compounds including, for example, basic compound hydroxide salts such as sodium, potassium, or tetraalkylammonium hydroxides; or tertiary alkyl amines such as tributyl amine, triethylamine, dimethylbenzylamine, dimethylbutylamine and the like; tertiary mixed alkyl-arylamines and substituted derivatives thereof such as dimethylaniline; heterocyclic amines such as imidazoles or pyridines and substituted derivatives thereof such as 2-methylimidazole, 2-vinylimidazole, 4-(dimethylamino)pyridine, 2-, 3-, or 4-vinylpyridine. Also useful are organometallic salts such as, for example, tin and zinc salts known to catalyze the condensation of, for example, isocyanates or cyanate esters with phenols. The organometallic salts useful in this regard are known to the art in numerous publications and patents well known to those skilled in this art.
Capping agents include compounds known in the literature to react with phenolic groups, and which contain carbon-carbon unsaturation for curing into the thermoset matrix via polymerization of its unsaturation following the capping reaction. Such compounds include both monomers and polymers containing, for example, anhydride, acid chloride, epoxy, carbonate, ester, isocyanate, cyanate ester, or alkyl halide radicals. Capping agents are not limited to organic compounds as, for example, phosphorus and sulfur based capping agents also are included. Examples of such compounds include, for example, acrylic anhydride, methacrylic anhydride, glycidylacrylate or glycidylmethacrylate, acetyl chloride, benzoyl chloride, diphenyl such as di(4-nitrophenyl)carbonate, acryloyl, methacryloyl or acetyl esters, phenylisocyanate, 3-isopropenyl-dimethylphenylisocyanate, cyanatobenzene, 2,2-bis(4-cyanatophenyl)propane), 3- or 4-(-chloromethyl)styrene, allyl bromide, and the like, carbonate and substituted derivatives thereof and mixtures thereof.
In one embodiment, preferred capped poly(phenylene ether)s of the present invention include those of the general structure, 1:
Qxe2x80x94(Jxe2x80x94K)mxe2x80x83xe2x80x831
wherein
Q is the residuum of a phenol;
J comprises recurring units of the following structure, 3:
wherein, for structure 3, R5-8 independently is selected from hydrogen, alkyl, alkenyl, alkynoyl, aryl, mixed alkyl-aryl hydrocarbons, wherein such groups may contain a substituent selected from carboxylic acid, aldehyde, alcohol, and amino functionality;
K has the following structure:
wherein R9-11 is a hydrogen or C1-100 alkyl or aryl or mixed alkyl or aryl group; X is an oxygen, and m ranges from 1-200.
Preferable capped poly(phenylene ether)s of the present invention include methacrylate capped polyphenylene ethers produced by reacting a poly(phenylene ether) with, for example, methacrylic anhydride in the presence of a capping catalyst. It is preferred that at least 10%, preferably at least 50%, and most preferably substantially all of the hydroxyl endgroups be capped.
A curable unsaturated monomer composition includes a member or members selected from the group consisting of (i) compounds containing a single polymerizable carbon-carbon double bond (monounsaturated compound) and (ii) compounds containing more than one polymerizable carbon-carbon double bond (polyunsaturated compound).
Mono-unsaturated compounds include, for example, monofunctional acrylate compounds and monofunctional styrenic compounds. Monofunctional acrylate compounds are compounds containing a single ethylenically unsaturated carbonyl group, i.e., a carbon-carbon double bond directly bonded to a carbonyl group. Representative of such compounds include, for example, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropenoate, isobornyl (meth)acrylate and tetrahydrofurfuryl methacrylate, halogenated acrylates such as pentabromobenzyl acrylate; and acrylic or methacrylic amides such methacrylamide, diacetone methacrylamide, N(beta-hydroxyethyl) methacrylamide.
Monofunctional styrenic compounds are compounds containing a single carbon-carbon double bond directly bonded to an aromatic or heterocyclic ring. Such compounds include, for example, styrene or 2- or 4-vinylpyridine or substituted derivatives thereof. The number of substituents may vary from between 1-5 and the substituent groups include C1-100 alkyl, alkoxy, aryloxy, aryl, bromo, chloro, fluoro, alkylhalo, phosphonate, sulfonate, and substituted derivatives therefrom. Derivatives containing styrene and substituted derivatives therefrom include: alkylstyrenes such as styrene, methylstyrene, ethylstyrene, isopropylstyrene, tertiary-butylstyrene, phenylstyrene and halogenated styrenes such as chlorostyrene, dichlorostyrene, trichlorostyrene, bromostyrene, dibromostyrene, tribromostyrene, fluorostyrene, difluorostyrene, trifluorostyrene, tetrafluorostyrene and pentafluorostyrene, halogenated alkylstyrenes such as chloromethylstyrene, alkoxystyrenes such as methoxystyrene, ethoxystyrene. Monounsaturated compounds may be used alone or in combination.
Brominated styrene compounds are particularly useful for preparing flame retardant formulations. Preferably, the bromine content of the brominated styrene compound should be greater than 45%, advantageously greater than 60%, and preferably greater than 70% by weight. The high bromine content of the brominated styrene compound allows preparation of circuit boards that comply with UL-94 flammability while concomitantly maintaining high PPE content and optimal dielectric properties.
Compounds containing greater than one polymerizable carbon-carbon double bond are referred to as polyunsaturated compounds. Polyunsaturated compounds include, for example, polyfunctional allylic compounds, unsaturated polymers, polyfunctional acrylates or acrylamides, and polyfunctional styrenic compounds.
Polyfunctional allylic compounds are compounds containing more than one allyl group per molecule. Illustrative examples include diallylphthalate, diallylisophthalate, triallylmellitate, triallylmesate, triallylisocyanurate, triallylcyanurate, and partial polymerization products prepared therefrom.
Unsaturated polymers are polymeric resins with number average molecular weights of between about 200-100,000 and comprise repeat units which further contain carbon-carbon double bonds. Thus, the unsaturated polymer contains on average greater than one carbon-carbon double bond per molecule. Typical examples of such unsaturated polymers include butadiene and isoprene containing polymers and copolymers derived therefrom. The polybutadiene or polyisoprene resins may be liquid or solid at room temperature. While liquid polybutadiene and polyisoprene resins may have a molecular weight greater than 5,000, advantageously such resins have a molecular weight of less than 5,000 and preferably their molecular weight ranges from between about 1,000 and 3,000.
The preferably liquid (at room temperature) resin portion of the composition maintains the viscosity of the composition at a manageable level during processing. It is preferable for printed circuit board applications that the polybutadiene and polyisoprene resins having at least 85% 1,2 addition by weight in order to exhibit the greatest cross-link density upon cure due to the large number of pendent vinyl groups available for crosslinking. High cross-link densities are desirable for electrical circuit substrates which must exhibit superior high temperature properties. A preferred resin is a low molecular weight polybutadiene liquid resin having greater than 90 wt.-% 1,2 addition. Polybutadiene resins of this type include, for example, polybutadiene B3000 resin, commercially available from Nippon Soda, Ltd. In applications unrelated to printed circuit boards, lower levels of 1,2-addition product may be tolerated.
The unsaturated polymer also may contain a thermoplastic elastomer such as linear or graft-type block copolymers that preferably have a polybutadiene or polyisoprene block (preferably as a 1,2 addition product) and a thermoplastic block that preferably is styrene or alpha-methyl styrene. A preferred copolymer is a styrene-butadiene-styrene triblock copolymer, e.g., Kraton DX1300 (commercially available from Shell Chemical Corp.).
The thermoplastic elastomer also may contain a second block copolymer similar to the first except that the polybutadiene or polyisoprene block is hydrogenated, thereby forming a polyethylene block (in the case of polybutadiene) or an ethylene-propylene copolymer (in the case of polyisoprene). When used in conjunction with the first copolymer, materials with greater xe2x80x9ctoughnessxe2x80x9d can be produced. A preferred second block copolymer material is Kraton(copyright) GX1855 (commercially available from Shell Chemical Corp.) which is believed to be a mixture of styrene-high 1,2 butadiene-styrene block copolymer and styrene-(ethylene-propylene)-styrene block copolymer.
Also included as suitable thermoplastic elastomers are copolymers of primarily 1,2-addition butadiene or isoprene with styrene, alpha-methyl styrene, acrylate or methacrylate, or acrylonitrile monomers; homopolymers or copolymers of ethylene, such as polyethylene, ethylene-propylene copolymer and ethylene-propylene-diene terpolymers, ethylene-ethylene oxide copolymers; natural rubber; norbornene polymers such as polydicyclopentadiene; hydrogenated diene polymers such as hydrogenated styrene-isoprene-styrene copolymers and butadiene-acrylonitrile copolymers; and like elastomers.
Additional unsaturated polymers include unsaturated polyester resins which are the polycondensation reaction product of one or more dihydric alcohols and one or more ethylenically unsaturated polycarboxylic acids. By polycarboxylic acid is meant polycarboxylic or dicarboxylic acids or anhydrides, polycarboxylic or dicarboxylic acid halides, and polycarboxylic or dicarboxylic esters. For example, suitable unsaturated polycarboxylic acids, and the corresponding anhydrides and the acid halides that contain polymerizable carbon-to-carbon double bonds, may include maleic anhydride, maleic acid, and fumaric acid. A minor proportion of the unsaturated acid, up to about forty mole percent, may be replaced by dicarboxylic or polycarboxylic acid that does not contain a polymerizable carbon-to-carbon bond. Examples thereof include the acids (and corresponding anhydrides and acid halides): O-phthalic, isophthalic, terephthalic, succinic, adipic, sebasic, methylsuccinic, and the like. Dihydric alcohols that are useful in preparing the polyesters include, for example, 1,2-propane diol (hereinafter referred to as propylene glycol), dipropylene glycol, diethylene glycol, 1,3-butanediol, ethylene glycol, glycerol, and the like. Examples of suitable unsaturated polyesters are the polycondensation products of (1) propylene glycol and maleic and/or fumaric acids; (2) 1,3-butanediol and maleic and/or fumaric acids; (3) combinations of ethylene and propylene glycols (approximately 50 mole percent or less of ethylene glycol) and maleic and/or fumaric acids; and (4) propylene glycol, maleic and/or fumaric acids and dicyclopentadiene reacted with water. In addition to the above described polyesters, dicyclopentadiene modified unsaturated polyester resins as described by the Pratt, et al. (U.S. Pat. No. 3,883,612 incorporated herein by reference) may be used. The foregoing examples are intended to be illustrative of suitable polyesters and are not intended to be all-inclusive. The molecular weight of the polymerizable unsaturated polyester may vary over a considerable range, but ordinarily those polyesters useful in the practice of the present invention have a molecular weight ranging from about 300 to 5000, and more preferably, from about 500 to 5000.
Polyunsaturated compounds also include polyfunctional acrylate or polyfunctional acrylamide compounds. Polyfunctional acrylate compounds are compounds containing greater than one acrylate moiety per molecule. Illustrative examples include compounds produced by condensation of an acrylic or methacrylic acid with a di-epoxide, such as bisphenol-A diglycidyl ether or butanediol diglycidyl ether. Specific examples include 1,4-butanediol diglycidylether dimethacrylate, bisphenol A diglycidylether dimethacrylate, and neopentylglycol diglycidylether dimethacrylate acrylic and methacrylic esters. Also included as polyacrylates are the condensation of reactive acrylate or methacrylate compounds with alcohols or amines to produce the resulting polyfunctional acrylates or polyfunctional acrylamides. Examples include: N,N-bis(beta-hydroxyethyl)methacrylamide, methylenebismethacrylamide, 1,6-hexamethylenebis(methacrylamide), diethylenetriamine tris(methacrylamide), bis(gamma-(methacrylamide)propoxy) ethane, beta-(methacrylamide) ethylacrylate, ethylene glycol di(methacrylate), diethylene glycol di(methacrylate), tetraethylene glycol di(meth)acrylateglycerol di(methacrylate), glycerol tri(methacrylate), 1,3-propylene glycol di(methacrylate), dipropyleneglycol di(methacrylate), 1,4-butanediol di(methacrylate), 1,2,4-butanetriol tri(methacrylate), 1,6-hexanedioldi(methacrylate), 1,4-cyclohexanediol di(methacrylate), 1,4-benzenediol di(methacrylate), pentaerythritoltetra(methacrylate), 1,5-pentanediol di(methacrylate), trimethylolpropane di(meth)acrylate, trimethylolpropane tri(methacrylate), 1,3,5-triacryloylhexahydro-1,3,5-triazine, 2,2-bis(4-(2-acryloxyethoxy)phenyl)propane and 2,2-bis(4-(2-acryloxyethoxy)-3-5-dibromophenyl)propane, 2,2-bis(4-(2-methacryloxy-ethoxy)phenyl)propane and 2,2-bis(4-(2-methacryloxyethoxy)-3-5-dibromophenyl) propane), 2,2-bis((4-acryloxy)phenyl)propane, 2,2-bis((4-methacryloxy)phenyl)propane and 2,2-bis((4-methacryloxy)-3,5-dibromophenyl)propane, 2,2-bis((4-methacryloxy)-3,5-dibromophenyl)propane.
Also included are polyfunctional styrenics (styrene compounds) which are compounds that contain greater than 1 carbon-carbon double bond directly attached to an aromatic or heterocyclic ring. These include, for example, 1,3-divinylbenzene, 1,4-divinylbenzene, trivinylbenzene, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, and halogenated derivatives thereof, as well as the vinylbenzylether of a polyphenol. Such compounds include the condensation products of chloromethylstyrene with a bisphenol, trisphenol or tetraphenol or more highly functionalized phenol. Such compounds include the bisvinylbenzyl ether of bisphenol-A, 3,3xe2x80x2,5,5xe2x80x2-tetrabromobisphenol-A, biphenol, 4,4xe2x80x2-thiodiphenol, 4,4xe2x80x2-oxydiphenol, 2,2xe2x80x2,4,4xe2x80x2-tetrabromo-3,3xe2x80x2,5,5xe2x80x2-tetramethyl-4,4-biphenol or the trisvinylether of 1,1,1-tris(4-hydroxyphenyl)ethane or the tetravinylether of 1,1,2,2-tetra(4-hydroxyphenyl)ethane or the polyfunctional vinylbenzylether formed by reaction of vinylbenzylchloride with a condensation product of phenol and formaldehyde such as a phenol-formaldehyde novolac.
In addition to the aforementioned components, curing catalysts for the unsaturated components also may be included. The curing agent for the unsaturated portion of the thermoset would include any compound capable of producing radicals at elevated temperatures. Such curing catalysts would include both peroxy and non-peroxy based radical initiators. Examples of peroxy initiators useful in the present invention include, for example, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide, t-butylcumyl peroxide, xe2x80x2-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumylperoxide, di(t-butylperoxy isophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, and trimethylsilylphenyltriphenylsilyl peroxide and the like. Typical non-peroxy initiators include compounds such as, for example, 2,3-dimethyl-2,3-diphenylbutane, 2,3-trimethylsilyloxy-2,3-diphenylbutane, and the like.
The aforementioned formulations also may be cured using irradiation techniques and would contain the aforementioned catalysts or those for such electron beam curing. Typical examples are electron beam and UV radiation.
PPE in which substantial portion, preferably substantially all, of the hydroxyl groups have been reacted with a compound containing ethylenic unsaturation may be blended with the unsaturated monomers either by dissolving the capped PPE in the unsaturated monomer resin or dispersing the capped PPE as a particulate of particle size 0.5-300 microns in size. Such an approach is particularly advantageous in blends of the capped PPE with allylic and/or styrenic monomers.
In an advantageous embodiment, (I) the poly(phenylene ether) and capping agent are combined with a capping catalyst which is combined with (II) a compound containing a polymerizable carbon-carbon double bond or triple bond, and optionally a member selected from (III) a polymerization catalyst, (IV) a flame retardant, and (V) a fibrous reinforcement. Compound (II) may comprise a member selected from (a) a compound containing on average one polymerizable carbon-carbon double bond or triple bond and (b) a compound containing on average greater than one polymerizable carbon-carbon double or triple bond. Such formulations are thermosettable and can provide improved solvent resistance.
Flame retardant compounds include those known to the art as described in numerous publications and patents known to those skilled in this art. Useful in formulating flame retardant compositions are, for example, brominated flame retardant compounds. Preferred brominated flame retardant compounds include, for example, 1,3,5-tris(2,4,6-tribromophenoxy)triazine, polybrominated diphenyl ethers, poly(2,6-dibromophenylene ether), brominated polystyrene, brominated cyclododecane, brominated bisphenol-A diglycidyl ether, hydroxyethyl ether, C1-100 aromatic or mixed aromatic-aliphatic phosphate esters such as triphenyl, tricresyl phosphate, tris(2-allylphenylphosphate), tris(2-methoxy-4-allylphosphate), tris(2-propenylphenyl)phosphate, tris(4-vinylphenyl)phosphate bis(diphenylphosphate ester)s of bisphenols such as bisphenol-A, resorcinol or hydroquinone or the bis(diphenyl phosphoramide)s of diamines such as 1,6-hexanediamine or piperidine, and alkylated or substituted derivatives therefrom. If brominated flame retardants are used, it is preferred that the bromine content of the brominated flame retardant be greater than 45%, advantageously greater than 60%, and preferably greater than 70%. The high bromine content of the flame retardant allows one to obtain UL-94 flammability and at the same time maintaining high PPE content and optimal dielectric properties.
Synthetic and/or natural resins can be used to further modify the properties of the compositions. Examples of the synthetic or natural resins for changing the properties include thermosetting resins, such as polyester resin, phenol resin, acrylic resin, urethane resin, silicone resin and alkyd resin; unvulcanized rubbers, such as polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene butadiene-styrene copolymer, polyisoprene, butyl rubber, natural rubbers; thermoplastic resins or low molecular resin having a molecular weight of less than several thousands, such as thermoplastic urethane resin, polyvinyl acetal resin and vinyl acetate resin; oligomers having a molecular weight of less than several thousands, such as polycarbonate, thermoplastic polyester, polyester-carbonate, polyphenylene ether, polyslfone, polyether sulfone, and polyacrylate which are engineering plastics; polyolefins having a molecular weight of less than several thousands, such as polyethylene, polypropylene, polybutene, and poly-4-methylpentene-1; and fluoroplastics having an molecular weight of less than several thousands, such as polytetrafluoro ethylene, tetrafluoro-propylene copolymer, perfluoroethylene-propylene copolymer, and fluoro-vinylidene.
Examples of fillers include silica powder, such as fused silica and crystalline silica boron-nitride powder and boron-silicate powders for obtaining cured products having low dielectric constant and low dielectric loss tangent; the above-mentioned powder as well as alumina, and magnesium oxide (or magnesia) for high temperature conductivity; and fillers, such as wollastonite, mica, calcium carbonate and talc or hollow glass microspheres, buckminsterfullanes, conductive carbon fibrils, nanotubes and xerogels. These inorganic fillers can be added to the thermosetting resin without any treatment, or after surface treatment by a silane coupling agent, or a titanate coupling agent. The fillers can be used in the form of particles or fiber. Organic fillers such as thermoplastics may also be used. Examples of thermoplastics include powdery engineering resins, such as polycarbonate, thermoplastic polyester, polyestercarbonate, polyphenylene ether, polysulfone, polyether sulfone, and polyacrylate; powdery polyolefins, such as polyethylene, polypropylene and poly-4-methyl pentene-1; and fluoroplastics, such as polytetrafluoro ethylene, tetrafluoroethylenerpropylene copolymer, and perfluoroethylene-propylene copolymer.
Reinforcements known to one skilled in the art can be used, including but not limited to, inorganic and organic materials, such as woven or non-woven glass fabrics of the E-, NE-, S-, T- and D-type glasses and quartz, and the like. Reinforcement may be in the form of glass roving cloth, glass cloth, chopped glass, hollow glass fibers, glass mat, glass surfacing mat, and non-woven glass fabric, ceramic fiber fabrics, and metallic fiber fabrics. Of particular value are glasses which have a very low dissipation factor, broadly less than 0.0015, advantageously less than 0.0010, and preferably less than 0.0007 measured at 1 MHz. Glasses with suitable a dissipation factor are for the most part are comprised of various combinations of Al2O3, SiO2, CaO, B2O3, MgO, and trace amounts (generally less than 2 parts by weight) of other oxide species. The weight ratios of Al2O3, SiO2, CaO, B2O3, MgO, and trace oxide species may vary over a wide range well-known to those skilled in the art to produce glasses with suitable dissipation factors. Preferred glasses are E-, NE-, D- and S-type glasses.
For many applications desirable glasses comprise about 12-30 parts Al2O3, about 45-70 parts SiO2, about 0.3-32 parts CaO, and about 2-24 parts B2O3, all parts being parts by weight. Especially desirable glasses comprise about 15-20 parts Al2O3, about 50-64 parts SiO2, about 5-10 parts CaO, and about 15-20 parts B2O3, all parts being parts by weight. In addition, synthetic organic reinforcing fillers may also be used in the present invention including, for example, organic polymers capable of forming fibers. Illustrative examples of such reinforcing organic fibers include, for example, poly(ether ketone), polyimide benzoxazole, poly(phenylene sulfide), polyesters, aromatic polyamides, aromatic polyimides or polyetherimides, acrylic resins, and poly(vinyl alcohol).
Fluoropolymers, such as polytetrafluoroethylene, can be used in the present invention also. Further included as reinforcement are natural organic fibers known to those skilled in the art, including cotton cloth, hemp cloth, felt, carbon fiber fabrics, and natural cellulosic fabrics such as Kraft paper, cotton paper; and glass fiber containing paper. Such reinforcing fillers may be provided in the form of monofilament or multifilament fibers and can be used either alone or in combination with other types of fiber, through, for example, co-weaving or core/sheath, side-by-side, orange-type or matrix and fibril constructions, or by other methods known to one skilled in the art of fiber manufacture. Such fillers may be supplied in the form of, for example, woven fibrous reinforcements, non-woven fibrous reinforcements, or papers.
Coupling agents, incorporated into the reinforcing material, are known in the art to improve adhesion of the fibrous reinforcement to the cured resin composition and through said incorporation are considered to an integral part of it. For purposes of the present invention, representative coupling agents include, for example, silane-, titanate-, zirconate-, aluminum-, and zircoaluminum-based coupling agents, as well as other agents known to those skilled in the art.
The composition may be cured to the desired degree by any of a number of techniques known to those skilled in the art, including, for example, heating, exposure to light or to an electron beam. When heat curing is used, the temperature selected can range from about 80xc2x0 to about 300xc2x0 C., and preferably from about 120xc2x0 to about 240xc2x0 C. The heating period can range from as short as about 1 minute to as long as about 10 hours, though such heating period advantageously ranges from about 1 minute to about 6 hours, and preferably ranges from about 3 hours to about 5 hours. Such curing may be staged to produce a partially cured and often tack-free resin which then is fully cured by heating for longer periods or temperatures within the aforementioned ranges.
Among the fillers that may be present in the composition are the following: particulate fillers such as talc, clay, mica, silica, alumina, and calcium carbonate. In addition, fillers may include conventional flame retardant additives such as bromine and phosphorus compounds, such as, for example: alkyl tetrabromophthalates and/or epichlorohydrin reaction products with mixtures of bisphenol A and tetrbromobisphenol A. Also included as fillers are plasticizers and/or flow promoters such as, for example, alkyl tetrabromophthalates, and fabric wettability enhancers (e.g., wetting agents and coupling agents). Even polar liquids such as n-butyl alcohol, methyl ethyl ketone, polysiloxanes, and tetrahydrofuran, may be advantageous under certain conditions. Also included as fillers are antioxidants, thermal and ultraviolet stabilizers, lubricants, antistatic agents, dyes, and pigments. The aforementioned filler materials may be used alone or in combination for purposes of the present invention.
The curable compositions of the invention may be dissolved in an effective amount of an inert organic solvent, typically to a solute content of about 30%-60% by weight. The identity of the solvent is not critical, provided that it may be removed by suitable means such as evaporation. Aromatic hydrocarbons, especially toluene, are preferred. The order of blending and dissolution also is not critical; however, in order to avoid premature curing, catalyst and hardener components generally should not be brought initially into contact with polyphenylene ether and polymerizable monomer composition at a temperature above about 60xc2x0 C. Proportions of components and bromine herein do not include solvent.
In this application all amounts and proportions are by weight and units are in the metric system, unless otherwise indicated.

Poly(phenylene ether)-polyvinyl thermosetting resin


The invention relates to a process for the oxidation of substituted trimethylcyclohexenyl compounds in the presence of microorganisms of the order Actinomycetales and to the use of microorganisms in oxidation reactions.

The invention relates to a process for the oxidation of substituted trimethylcyclohexenyl compounds in the presence of microorganisms of the order Actinomycetales and to the use of microorganisms in oxidation reactions.
Compounds having a trimethylcyclohexenyl ring occur widely in nature. They are important intermediates in the terpenoid metabolism and occur, for example, during carotinoid biosynthesis. They can be isolated from a series of natural sources. For example, in addition to the carotinoids, a large number of fragrances and/or flavorings have a trimethylcyclohexenyl ring. They are also found in a large number of vegetable oils.
There have been a variety of attempts in the past at the biotechnological oxidation of compounds having a trimethylcyclohexenyl ring. Thus, Mikami et al. (Appl. Environ. Microbiol., Vol. 41, No. 3, 1981: 610-617) describes the microbial transformation of xcex2-ionone and xcex2-methylionone by the fungus Aspergillus niger. The main products of the reaction with xcex2-ionone as starting material were identified as (R)-4-hydroxy-xcex2-ionone and (S)-2-hydroxy-xcex2-ionone, and also 2-oxo-, 4-oxo-, 3,4-dehydro-, 2,3-dehydro-4-oxo-, 3,4-dehydro-2-oxo-, (S)-2-acetoxy-, (R)-4-acetoxy-, 5,6-epoxy-xcex2-ionone and 4-(2,3,6-trimethylphenyl)but-3-en-2-one. Analogous transformation products were identified with xcex2-methylionone as starting material. A reaction with such a large number of secondary products is unsuitable for industrial purposes.
DE 32 43 091 describes the oxidation of xcex2-ionone to (R)-4-hydroxy-xcex2-ionone by the fungus Gongronella butleri. In this reaction, the principal secondary product formed is 2-hydroxy-xcex2-ionone, which is hydroxylated in the 2-position and an undesired product.
A reaction which is an improvement on Mikami et al. is described by Yamazaki et al. (Appl. Environ. Microbiol., Vol. 54, No. 10, 1988: 2354-2360). Yamazaki uses the fungus Aspergillus niger JTS 191 as catalyst for the reaction. The main products described are a cis/trans isomer mixture (=cis-3-hydroxy-xcex1-ionone and trans-3-hydroxy-xcex1-ionone), together with 3-oxo-xcex1-ionone. Other secondary products which were identified are 2,3-dehydro-xcex1-ionone, 3,4-dehydro-xcex1-ionone and 1-(6,6-dimethyl-2-methylene-3-cyclohexenyl)buten-3-one. Again, this process cannot be exploited industrially due to the spectrum of main and secondary products, specifically due to the cis/trans isomer mixture. Nor does the process described in FR 2 661 190, in which the fungus Mucor is employed, lead to satisfactory results.
In 1995, a fed-batch biotransformation of xcex2-ionone using Aspergillus niger was described by Larroche et (Appl. Microbiol. Biotechnol., 43, 1995: 222-227). This biotransformation not only yields 4-hydroxy-xcex2-ionone, but also 2-hydroxy-xcex2-ionone and 4-oxo-xcex2-ionone, both of which are undesired.
Our own work with a variety of fungi as catalysts has demonstrated that the oxidation of compounds having a trimethylcyclohexenyl ring leads to a multiplicity of main and secondary products.
It is an object of the present invention to provide a process for the oxidation of compounds having trimethylcyclohexenyl rings which does not exhibit the above-mentioned disadvantages and which selectively leads to oxidation products.
We have found that this object is achieved by the process according to the invention for the oxidation of compounds of the structure I
to compounds of the structure II
the substituents in formulae I and II being as defined below:
R1=substituted or unsubstituted, branched or unbranched, saturated or unsaturated C1-C8-Alkyl-,
R2 and R3 independently of one another are hydrogen, oxo- or hydroxyl-, at least one radical R2 or R3 being other than hydrogen,
which comprises carrying out the oxidation of the compounds of the structure I in the presence of bacteria of the order Actinomycetales.
It is preferred to use the process according to the invention for oxidizing compounds of the structure Ia
to compounds of the structure IIa
in the presence of bacteria of the order Actinomycetales, the substitutent R1 in formulae I and IIa being as defined above and R2 being oxo- or hydroxyl-.
In the compounds of the formulae I, Ia, II and IIa, R1 denotes substituted, or unsubstituted, branched or unbranched, saturated or unsaturated C1-C8-alkyl-.
Saturated alkyl radicals which may be mentioned are substituted or unsubstituted branched or unbranched C1-C8-alkyl chains, such as, for example, methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl-, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl or n-octyl.
Unsaturated alkyl radicals which may be [lacuna] are subsituted or unsubstituted, branched or unbranched C2-C8-alkenyl chains, such as, for example, ethenyl, propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methylpropenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1,2-dimethyl-1-propenyl, 1,2-dimethyl-2-propenyl, 1-ethyl-1-propenyl, 1-ethyl-2-propenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-methyl-1-pentenyl, 2-methyl-1-pentenyl, 3-methyl-1-pentenyl, 4-methyl-1-pentenyl, 1-methyl-2-pentenyl, 2-methyl-2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 1-methyl-3-pentenyl, 2-methyl-3-pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 1-methyl-4-pentenyl, 2-methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl, 1,1-dimethyl-2-butenyl, 1,1-dimethyl-3-butenyl, 1,2-dimethyl-1-butenyl, 1,2-dimethyl-2-butenyl, 1,2-dimethyl-3-butenyl, 1,3-dimethyl-1-butenyl, 1,3-dimethyl-2-butenyl, 1,3-dimethyl-3-butenyl, 2,2-dimethyl-3-butenyl, 2,3-dimethyl-1-butenyl, 2,3-dimethyl-2-butenyl, 2,3-dimethyl-3-butenyl, 3,3-dimethyl-1-butenyl, 3,3-dimethyl-2-butenyl, 1-ethyl-1-butenyl, 1-ethyl-2-butenyl, 1-ethyl-3-butenyl, 2-ethyl-1-butenyl, 2-ethyl-2-butenyl, 2-ethyl-3-butenyl, 1,1,2-trimethyl-2-propenyl, 1-ethyl-1-methyl-2-propenyl, 1-ethyl-2-methyl-1-propenyl, 1-ethyl-2-methyl-2-propenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-heptenyl, 6-heptenyl, 1-octenyl, 2-octenyl, 3-octenyl, 4-octenyl, 5-octenyl, 6-octenyl or 7-octenyl,
Other unsaturated alkyl radicals which may be [lacuna] are substituted or unsubstituted, branched or unbranched C2-C6-alkynyl chains, such as, for example, ethynyl-, prop-1-yn-1-yl, prop-2-yn-1-yl, n-but-1-yn-1-yl, n-but-1-yn-3-yl, n-but-1-yn-4-yl, n-but-2-yn-1-yl, n-pent-1-yn-1-yl, n-pent-1-yn-3-yl, n-pent-1-yn-4-yl, n-pent-1-yn-5-yl, n-pent-2-yn-1-yl, n-pent-2-yn-4-yl, n-pent-2-yn-5-yl, 3-methylbut-1-yn-3-yl, 3-methylbut-1-yn-4-yl, n-hex-1-yn-1-yl, n-hex-1-yn-3-yl, n-hex-1-yn-4-yl, n-hex-1-yn-5-yl, n-hex-1-yn-6-yl, n-hex-2-yn-1-yl, n-hex-2-yn-4-yl, n-hex-2-yn-5-yl, n-hex-2-yn-6-yl, n-hex-3-yn-1-yl, n-hex-3-yn-2-yl, 3-methylpent-1-yn-1-yl, 3-methylpent-1-yn-3-yl, 3-methylpent-1-yn-4-yl, 3-methylpent-1-yn-5-yl, 4-methylpent-1-yn-1-yl, 4-methylpent-2-yn-4-yl or 4-methylpent-2-yn-5-yl.
Suitable substituents for the above-mentioned radicals of R1 are, in principle, all conceivable consistuents, for example one or more substituents such as oxo, acyl-, CHR4OR5xe2x80x94 (=acetal), halogen such as fluorine, chlorine or bromine, cyano, nitro, amino, hydroxyl, alkyl, cycloalkyl, aryl, alkoxy, benzyloxy, phenyl or benzyl, preferably oxo, hydroxyl-, acyl- or CHR4OR5xe2x80x94 (=acetal), alkyl and cycloalkyl. R4 and R5 in the radicals independently of one another denote C1-C4-Alkyl- or C3-C8-cycloalkyl-.
Polyunsaturated substituted or unsubstituted, branched or unbranched C2-C8-alkyl chains may advantageously also be present as radicals R1 in formulae I, Ia, II or IIa. The chain may contain a plurality of double bonds in conjugated or non-conjugated form, or double bonds and triple bonds may simultaneously exist in the chain. The preferred radicals 3-methyl-1,4-dipenten-1-yl- or 3-methylpent-1-yn-4-en-(5)-yl- may be mentioned by way of example.
Other preferred radicals R1 which may be mentioned are radicals such as ethynyl-, hydroxymethyl-, formyl-, 3-methyl-3-hydroxy-1,4-dipenten-1-yl- or 3-hydroxy-3-methylpent-1-yn-4-en-5-yl-.
R2 and R3 [sic] in the compounds of the formulae II and IIa independently of one another denote hydrogen, oxo or hydroxyl-, at least one radical R2 or R3 being other than hydrogen and R2 in formula IIa not being hydrogen. Oxo is always an oxygen bonded via a double bond.
The compounds of the structures I, Ia, II and IIa contain a double bond which may exist in two positions: either in the 4- or in the 5- position of the cyclohexane ring.
In principle, all bacteria of the order Actinomycetales are suitable for the process according to the invention. Bacteria of this order, of which the formation of branched filaments is typical, are Gram-positive. Like all suitable microorganisms, these bacteria can be isolated readily by methods known to those skilled in the art, for example from soil, compost or water samples, or obtained from culture collections like the ATCC or DSMZ. Methods for isolating these bacteria can be found, for example, in the textbooks The Prokaryotes (Eds. Mortimer T. Starr, Heinz Stolp, Hans G. Trxc3xcper, Albert Balows, Hans G. Schlegel, Springer Verlag, 1981, 2nd Edition, Chapter 147, ISBN 3-540-08871-7) or Mikrobiologisches Praktikum [Experiments in Microbiology] (Eds. [sic] Drews, 3rd Edition, Springer Verlag, 1976, pages 47 and 48). Bacteria for the process according to the invention are preferably selected from the group consisting of Nocardia, Rhodococcus, Mycobacterium, Micrococcus, Proactinomyces and of the family Streptomycetaceae of the genera Streptomyces, Streptoverticillium, Chainia, Microellobosporia and Kitasatoa.
Preferably, bacteria of the family Streptomycetaceae with the genera Streptomyces, Streptoverticillium, Chainia, Microellobosporia and Kitasatoa are used in the process according to the invention, especially preferably bacteria of the genus Streptomyces. Bacteria of genus and species such as Streptomyces arenae, Streptomyces antibioticus, Streptomyces griseus, Streptomyces violaceoniger, Streptomyces exfoliatus, Streptomyces griseoviridis, Streptomyces fradiae, Streptomyces tendae or Streptomyces hygroscopicus are very especially preferably used.
The multiplicity of the bacteria which are suitable for the reaction reflects the highly eventful history of taxa of the order Actionomycetales [sic]. The taxonomic position of the organisms mentioned has recently undergone a radical change and is still in flux since incorrect names of genera and species are being corrected and new genera are being assigned to existing strains. Close relationships exist within these genera and species. Bacteria which perform the process according to the invention are very likely to be found amongst the above-mentioned microorganisms. For example, 215 bacteria of the preferred genus Streptomyces were tested for the reaction according to the invention. 15 of these organisms performed the reaction. 15 of these organisms oxidized the specific substrate xcex2-ionone, and 6 of these organisms were also capable of oxidizing xcex1-ionone. This means that approximately 6% of the bacteria tested performed the desired reaction of xcex2-ionone and approximately 3% that of xcex1-ionone. This means that those skilled in the art have a good chance (approximately 3 to 6%) of testing any microorganisms from the order Actinomycetales, specifically the genus Streptomyces, for the reaction.
Five organisms of the bacteria tested which are particularly capable of performing the reaction according to the invention have been deposited at the DSMZ under the following numbers: DSM 12134 (=Streptomyces arena Txc3xc495), DSM 12133 (=S. antibioticus Txc3xc46), DSM 12135 (=S. griseus ATCC 13273), DSM 12131 (=S. fradiae Txc3xc27) and DSM 12132 (=S. violaceoniger Txc3xc38).
Advantageously, bacteria are used in the process according to the invention whose productivity is already increased over that of the wild-type isolates. Such microorganisms are expediently obtained by mutating the wild-type strains which are capable of performing the biotransformation according to the invention (see scheme I).
Known microbiological techniques may be employed for generating such mutants. To trigger mutations, all customary methods may be used, such as the use of mutagenic substances, for example, nitrosoguanidine, ethyl methanesulfonate, sodium nitrite, or exposure to electromagnetic radiation such as UV, gamma or X-ray radiation. Transposable genetic elements, such as transposons or IS elements, may furthermore be used for mutagenesis. To isolate the mutants, it is possible, for example, to exploit their capability of performing this biotransformation at an increased rate (measurement by GLC analysis, see examples).
However, such organisms may also be selected in continuous culture from a population of less well adapted individuals by adding appropriately increasing starting material/product concentrations to the fresh medium.
The biotransformation of the process according to the invention can be carried out on growing cells, quiescent cells, cell extracts or purified enzymes, advantageously in the presence of natural or artificial reduction equivalent donors and/or acceptors. The reaction is preferably carried out on growing cells.
The process according to the invention for the oxidation of compounds of the formula I or Ia to compounds of the formula II or IIa is advantageously suitable for the selective oxidation of xcex1- or xcex2-ionones (see scheme I). In this oxidation, monooxidized products are preferentially formed. Hardly any secondary products are formed in the reaction, if at all.
The oxidation of xcex2-ionone in the process according to the invention preferentially yields 4-hydroxy-xcex2-ionone, i.e. only one product, in good yields. The bacteria only form one, as yet unidentified, product in the presence of starting material (=xcex2-ionon) and product (4-hydroxy-xcex2-ionone) in such minute amounts that it cannot be identified analytically. It is unclear whether this compound is a secondary product of the reaction. This compound is found in amounts of xe2x89xa64%, preferably xe2x89xa62%, especially preferably xe2x89xa61%, based on the empirical parameters of GLC analysis (starting material+product; see scheme II).
The oxidation of xcex1-ionone in the process according to the invention preferentially yields 3-hydroxy-xcex2-ionone, i.e. only one product, in good yields. The bacteria only form one, as yet unidentified, product in the presence of starting material (=xcex1-ionone) and product (3-hydroxy-xcex2-ionone) in such minute amounts that it cannot be identified analytically. It is unclear whether this compound is a secondary product of the reaction. This compound is found in amounts of xe2x89xa66%, preferably xe2x89xa64%, especially preferably xe2x89xa63%, very especially preferably xe2x89xa61%, based on the empirical parameters of GLC analysis (starting material+product; see scheme IIIa).
The oxidation according to the invention of compounds of the structure I or Ia advantageously leads to compounds of the structure II or IIa, in which the substituents R1 and R2 are in the trans-position relative to the ring plane. Thus, the process according to the invention preferentially leads to regio- and stereoselective oxidations.
Scheme IIIb demonstrates this by way of example for the oxidation of xcex1-ionone (=specific compound of the structure Ia) to trans-3-hydroxy-(6R)-xcex1-ionone and/or trans-3-hydroxy-(6S)-xcex1-ionone (=specific compounds of the structure IIa). No cis-isomers are formed.
In the process according to the invention, bacteria are grown in a medium which permits the growth of these organisms. This medium may be a synthetic or a natural medium. Depending on the organism, media known to those skilled in the art will be used. To allow microbial growth, the media used contain a carbon source, a nitrogen source, inorganic salts and, if appropriate, minor amounts of vitamins and trace elements.
Examples of advantageous carbon sources are sugars such as mono-, di- or polysaccharides such as glucose, fructose, mannose, xylose, galactose, ribose, sorbose, ribulose, lactose, maltose, sucrose, raffinose, starch or cellulose, complex sugar sources such as molasses, sugar phosphates such as fructose-1,6-bisphosphate, sugar alcohols such as mannitol, polyols such as glycerol, alcohols such as methanol or ethanol, carboxylic acids such as citric acid, lactic acid or acetic acid, fats such as soya oil or rapeseed oil, amino acids such as glutamic acid or aspartic acid or amino sugars which may simultaneously also be used as the nitrogen source.
Advantageous nitrogen sources are organic or inorganic nitrogen compounds or materials which contain these compounds. Examples are ammonium salts such as NH4Cl or (NH4)2SO4, nitrates, urea, or complex nitrogen sources such as corn steep liquor, brewers"" yeast autolysate, soybean flour, wheat gluten, yeast extract, meat extract, casein hydrolysate, yeast or potato protein, all of which can frequently also be simultaneously used as the nitrogen source.
Examples of inorganic salts are the salts of calcium, magnesium, sodium, manganese, potassium, zinc, copper and iron. Anions of these salts to be mentioned are, in particular, the chlorine [sic], sulfate and phosphate ions. An important factor for increasing the productivity in the process according to the invention is the addition of Fe2+ or Fe3+ salts and/or potassium salts to the production medium.
If appropriate, other growth factors are added to the nutrient medium, such as, for example, vitamins or growth promoters such as riboflavin, thiamine, folic acid, nicotinic acid, pantothenate or pyridoxine, amino acids such as alanine, cysteine, asparagine, aspartic acid, glutamine, serine, methonine [sic] or lysine, carboxylic acids such as citric acid, formic acid, pimelic acid or lactic acid, or substances such as dithiothreitol.
The fermentation of the bacteria, or the biotransformation, may be effected continuously or batchwise. As a rule, the oxidation is performed using active bacteria, but it is also successfully carried out when using quiescent bacteria, albeit at a considerably lower rate.
The mixing ratio of the nutrients mentioned depends on the type of fermentation and is decided for each individual case. All of the components of the medium may be introduced into the fermentation vessel at the beginning of the fermentation, if appropriate after having been sterilized separately or jointly, or else they may be fed continuously or batchwise during the fermentation, as required.
The culture conditions are specified in such a way that the organisms"" growth is optimal and that the best possible yields are achieved. Preferred culture temperatures are at 15xc2x0 C. to 40xc2x0 C. Temperatures between 25xc2x0 C. and 37xc2x0 C. are especially advantageous. The pH is preferably maintained in a range from 3 to 9. pH values of between 5 and 8 are especially advantageous. In general, an incubation time of a few hours to several days, preferably 8 hours up to 21 days, especially preferably 4 hours to 14 days, will suffice. The maximum amount of product is concentrated in the medium within this period.
Advantageous media and growth conditions for the process according to the invention can be found, for example, in the above-mentioned textbook xe2x80x9cThe Prokaryotesxe2x80x9d or in culture collection catalogues, such as that of the DSMZ or the ATCC.
The oxidation process according to the invention may be carried out continuously, batchwise or fed-batchwise, it being possible to introduce the starting material at the beginning of the fermentation or else add it later, continuously or batchwise. The concentration of starting material is advantageously in a range from 0.1 to 5 g/l, concentrations of 0.5 to 2 g/l being preferred. Alternatively, the starting material may be added in the form of a dilute aqueous or organic solution.
The process according to the invention leads to advantageous product yields of at least 10, preferably 20, especially preferably 30%, based on starting material employed.
The concentration of starting material is preferably controlled within a range which ensures that no growth-inhibitory concentrations of the starting material are reached. This can be determined readily for a particular starting material and a given microorganism by simple preliminary experiments with which those skilled in the art will be familiar. For example, growth curves of the organisms are recorded and the starting material concentrations at which the growth rate decreases markedly are thus analyzed.
The conversion can be monitored and checked regularly by sampling and analyzing the samples (GLC). The products may be isolated and purified from the culture liquid by known methods (see examples). Expediently, the solid biomass is separated from the nutrient medium or transformation medium, the product of interest is extracted, for example using an organic solvent, and the product of interest is isolated from the extract phase. Column chromatography methods are also expedient for work-up.
The invention is illustrated in greater detail by the examples which follow.

Method for the oxidation of substituted trimethylcyclohexenyl compounds with bacteria of the family Streptomycetaceae


A water pump having a pump impeller and a cup-like disk disposed to be movable along a rotation shaft driven by the engine, a space for passing water being formed between the pump impeller and the cup-like disk, the pump impeller and the cup-like disk being engaged each other by the engagement of vanes and grooves formed at least one side of them respectively, the distance between the pump impeller and the cup-like disk being varied according to the change of water temperature or the change of rotation speed of the engine, thereby to make it possible to adjust the water flow rate of the pump.

1. Field of the Invention
This invention relates to a water pump which can varies the capacity of a pump by varying the working area of the vane portion of an impeller.
2. Prior Art
The cooling system for engines is generally provided with a water pump driven by the engine, for circulating water to cool a cylinder block and a cylinder head.
The conventional water pump of the above type has a pump impeller fixed to the end of a rotation shaft rotated by the engine, said pump impeller being constructed of a boss fix to the rotation shaft, a flange extending outward in a radial direction, and a vane formed on the flange. Consequently, such conventional water pump operates always with full capacity regardless of whether the engine is warmed up or cooled, and as the result, the power-loss of water pump becomes high and the operation efficiency becomes low.
A water pump for solving the above problem is disclosed in the Japanese Laid-open Utility Model Bulletin Jitsu-kai-sho No. 59-97295 (97295/1984). This water pump employs a structure such as shown in FIG. 11. In the figure, a rotation shaft 61 rotated by an engine (not illustrated) has pump impeller 62 fixed thereto and wax type thermostat 64 installed on the end of the rotation shaft 61. Also disk 65 is fixed to thrust shaft 64' which is axially movable by said thermostat 64. Compression spring 66 is installed between the base of the pump impeller 62 and the base of the disk 65. The pump impeller 62 is constructed of cylindrical boss section 62a, a flange section 62b which extends outwardly in the radial direction from said boss section 62a, a vane section 62c formed on said flange section 62b. The disk 65 has a cuplike recession formed at the center and has nearly the same cross sectional shape and radius as those of flange section 62b of the pump impeller 62. There are formed notches, to which vane section 62c of pump impeller 62 is fitted, in the circular portion of the disk 65 corresponding to the number of vanes.
When the temperature of the engine cooling water is relatively high, the thermostat 64 detects the temperature and moves the disk 65 fixed to the thrust shaft 64' leftward in the figure against spring 66. Consequently, the working area of vane section 62c of pump impeller 62 (area of the portion of the vane protruding from the notch of disk 65) increases and the working range of pump impeller 62 widens, resulting in increased flow rate of the pump. Conversely, when the temperature of the engine cooling water is relatively low, disk 65 moves rightward, the working area of the vane becomes smaller, and working range of pump impeller 62 narrows, resulting in decreased flow rate of the pump.
By the above-mentioned construction and operation, the water pump proposed in the Jitsu-kai-sho No. 59-97295 can make it possible to reduce the power-loss, increase the operation efficiency and reduce the fuel expense, as compared with the conventional water pump in which the pump impeller is only fixed to the rotation shaft, because it controls the water flow rate from the pump so as to make it correspond to the temperature variation by detecting the temperature of engine-cooling water. Still, this water pump has a problem to be solved, too. Namely, when it is necessary to lower the water flow rate of the water pump, the capability of pump impeller 62 should be reduced by moving the disk 65 rightward to narrow the working area of the vane. But, in the above situation, the cooling water flows in the direction to the flange 62b of pump impeller 62 through a gap between the cut portion of disk 65 and the pump impeller 62 and is disturbed in between the pump impeller 62 and the disk 65. Consequently, the water flow rate of the pump and the power loss are not reduced to such extent as expected.


A soldering flux includes a resin in an aqueous composition. The flux can also include an activating agent and a surface-active agent that promotes surface wetting. The flux can be used to coat circuits and a printed circuit board. The resin can be non-acidic and/or in an emulsified form.

Electronics products, such as computers and communications equipment, employ printed wiring boards (PWB""s), or printed circuit boards (PCB""s, the two terms used interchangeably throughout). During the assembly of a PCB, components, such as integrated circuits, connectors, dual in-line packages, capacitors and resistors, are soldered to conductive contacts that form part of a circuit-interconnecting pattern on the board. In a solder wave process, components can be mounted on the bottom side of the board with adhesive if they are lead less and on the top of the board via through-holes if the components are leaded wherein leads of a component are passed through a plated through hole in the board. Portions of the leads that protrude through the back or underside of the board are then crimped over and secured to the board with solder that is applied as a molten xe2x80x9csolder wavexe2x80x9d across the underside of the board. The solder that is thereby applied to the board forms a bond and electrical connection between the surfaces of the component leads and the contacts on the board.
Prior to the actual soldering of such assemblies, a flux is ordinarily applied to the surfaces to be joined to chemically prepare the surfaces to receive the solder. The flux removes and prevents formation of oxides on the surfaces and thereby promotes wetting and continuity of the solder at its interface with the circuit. Consequently, the quality and integrity of electrical and mechanical connections between adjoining surfaces are likewise promoted. Typically, the flux is applied by spray, wave or foam. The fluxed assembly is then pre-heated prior to soldering to volatilize the flux carrier from the surfaces of the PCB.
Soldering fluxes that have been used by the electronics industry in the wave soldering of printed wiring assemblies have traditionally included ingredients that are detrimental to the environment and/or that necessitate the use of post-soldering cleaning agents, which also present undesirable environmental risk. For example, typical resin/rosin-containing fluxes are solvent based (e.g., isopropyl alcohol based), wherein the solvent generally volatilizes in the form of volatile organic compounds (VOC""s) that pollute the environment and that may also harm the ozone layer.
As the environmental consequences of electronics production processes have become better understood, and in order to meet increasingly strict government regulations, the art has sought to avoid the above-described problems by proposing water-based fluxes that include acidic rosin. To improve the solubility of the acidic rosin in water, a volatile basic compound, such as ammonia or an amine, is incorporated into the composition.
The soldering flux described herein can be used for flux coating when soldering electronic assemblies such as printed wiring assemblies. The flux is an aqueous composition that includes a resin.
The flux can be substantially free of volatile organic compounds such as solvents and amines. In addition to the water and resin, the flux can further include activating agent(s) such as organic acids (e.g., mono-, di-, and tricaboxylic acids) and surface-active agent(s) that promote surface wetting. In one embodiment, a non-acidic resin in the form of a pentaerythritol ester of hydrogenated rosin is used. In other embodiments, the resin can be a rosin.
The flux can be applied to a substrate to clean the oxidation from the metallic surfaces (e.g., surfaces of copper, tin, tin-silver, tin-lead, palladium, etc.) and to protect the surfaces from further oxidation. The water can then be evaporated from the flux, followed by application of solder (e.g., via a wave soldering process) to the flux and use of the solder to secure an electronic component to the substrate. The flux residues need not be removed from the board before the board is put into use in an electronics application.
Various embodiments of these soldering fluxes offer numerous advantages over those known in the art. In particular, many advantages can be derived from the use of fluxes that are free of volatile organic compounds.
For example, basic nitrogen compounds, particularly amines (volatile and/or non-volatile at soldering temperatures), that have been used in known flux compositions tend to be flammable, and noxious if volatile and, accordingly, present numerous health and environmental hazards. Further, if the basic compounds that are used are non-volatile, they can react with the acidic resins and metallic ions to produce residues in the form of rosin soaps and metal salts, which are hygroscopic and conductive and, if left on the soldered circuits, can compromise the surface insulation of the PCB assembly. Moreover, in hot and humid environments, these residues absorb moisture, which promotes dendritic growth, which, in turn, causes current leakage. Consequently, an extra step is generally needed after soldering to completely eliminate the residues of the basic compound from the PCB. This post-soldering cleaning is often performed with a cleaning agent (e.g., a chlorofluorocarbon or other organic solvent mixtures), which, itself, presents environmental hazards. Yet another disadvantage of using amines in accordance with known teachings is that these amines can react with an organic acid activator in the flux solution. To offset the loss due to this reaction, relatively large quantities of amines may be needed to provide a stable solution.
Fluxes that are free or substantially free of amines, such as those described herein, can avoid or ameliorate each of these problems. Consequently, flux residues can remain on the board without compromising the electrical reliability of the circuit assemblies, thereby eliminating the need to either wash the flux residues from the board surface or cover the residues with a conformal coating.
Further, fluxes that are also free or substantially free of volatile organic solvents that are typically used in known fluxes also remove or minimize the health and environmental hazards associated with those components. By eliminating the presence of both the amines (volatile or non-volatile) and the volatile organic compounds (solvents) from the flux, as described herein, many of these problems can be entirely or substantially eliminated.
Additionally, the fluxes described herein can provide a high grade of solderability. The term, xe2x80x9csolderability,xe2x80x9d as used herein, refers to an ability to provide a clean metallic surface on the substrate, as well as on the component leads, so that a high degree of wetting and coalescence of molten solder on the PCB surface can be achieved.
The soldering fluxes of this disclosure are aqueous compositions comprising one or more dispersed resins. The fluxes typically also include activating agent(s) and surface-active agent(s) that promote surface wetting. The flux can easily be prepared by the addition of appropriate proportions of resin dispersion, activators and surfactants to water at room temperature along with other property-enhancing additives, and mixing to form an aqueous solution. The end composition is 70 to 97% water by weight. Preferred embodiments include fluxes in which the range of water is 90 to 96% by weight of the flux.
In particular embodiments, the resin is a pentaerythritol ester of hydrogenated rosin, commercially available in the form of an aqueous dispersion, known as PENTALYN H-55WBX resin dispersion (available from Hercules, Inc., Wilmington, Del., USA). Examples of other resins that can be used, and which are also available in the form of aqueous dispersions, include TACOLYN 1065 resin dispersion, TACOLYN 1070 resin dispersion and FORAL 85-55WKX resin dispersion (each of which is also available from Hercules, Inc., Wilmington, Del., USA). The resin solid forms 0.1 to 15%, by weight, of the flux, with a preferred range of 0.1 to 10%, by weight, resin solid in the flux. The preferred range can be formed by adding between about 0.2 to about 18.2%, by weight, resin dispersion (55% solid resin) to the aqueous composition.
Unlike resins used in known aqueous fluxes, such as those disclosed in U.S. Pat. No. 5,863,355, which teaches that the resin used in its flux preferably has an acid number of at least 180, the resins listed in the preceding paragraph have no acid number, i.e., are non-acidic. xe2x80x9cAcid numberxe2x80x9d is a measure of the free acid content of a substance, as determined by the number of milligrams of potassium hydroxide (KOH) required to neutralize one gram of the substance.
A particular benefit of the use of such non-acidic resins is that these water-based soldering flux compositions can be substantially free of volatile organic compounds and volatile basic compounds because the non-acidic resins described herein are dispersed in water without the use of volatile organic compounds such as solvents and/or amines. Though trace quantities of these compounds may be present in the flux either as contaminants or as minor components of any of the additives (a minor component in a surfactant, for example), the flux, as a whole, is still considered for purposes of this disclosure to be substantially and essentially free of volatile organic and basic compounds (less than 1% by weight). By freeing the flux composition of non-volatile amines, residues of the flux composition can remain on the printed circuit board without having either (a) to wash the residues from the surface of the board or (b) to provide a conformal coating (e.g., in the form of a moisture barrier layer) over the flux residue to prevent shorting or corrosion of the printed circuits. Rather, the flux layer, itself, acts as a protective layer. However, if flux removal is desired, non-flammable, low-VOC, solvent cleaning compositions can be applied to remove the flux. Further, if the added protection of a conformal coating is desired, a coating of, for example, urethane, silicone or paralyn can be applied.
The activator system of the flux includes one or more water-soluble organic acids and/or ionic or non-ionic halides. xe2x80x9cActivatorsxe2x80x9d are chemicals that, when added to the flux, enable the flux to remove oxides from the metal surfaces to be soldered. It is advantageous to select activators that exhibit sufficient solubility in water to remain fully in solution after one or more freezing/thawing cycles of the flux. More particularly, should the flux be frozen during transportation or storage, the use of such activators ensures that the flux will be in solution form after thawing, whereby it is still effective for use. Generally speaking, solubility in water of at least about 5 grams per 100 cm3 at 20xc2x0 C. (68xc2x0 F.) will be sufficient for this purpose. Activators of low solubility do not offer the foregoing advantage, because they drop out and remain out of solution when the flux is subjected to a freeze/thaw cycle, whereby the flux cannot be used without further processing (such as by heating the flux sufficiently above room temperature to restore the solution).
The total activator content of the flux is between about 0.2 and about 8% by weight of the flux. Lower activator content may not provide sufficient fluxing activity, while a higher activator content may result in excessive residues, which could adversely affect the finished soldered assembly. Of course, as between stronger and weaker activators, stronger activators should be used in amounts more toward the lower end of the indicated range. In particular embodiments, the activator content is from 0.5 to about 4% by weight of the flux.
Examples of activators suitable for use in the present invention include organic activators such as carboxylic acids, sulfonic acids, phosphonic acids, phosphate esters, amino acids, alkanolamines, and combination thereof. Such activators are only weakly ionic relative to halide-containing activators, such as amine hydrohalides (e.g., amine hydrochlorides and amine hydrobromides) commonly used in the electronics industry. Moreover, being halide-free, these activators do not lead to the regenerative corrosion reaction which takes place when halides are present.
Specific chemicals that are suitable for use as activators include succinic acid (C4H6O4), itaconic acid (C5H6O4); adipic acid (C6H10O4); glutaric acid (C5H8O4); and non-ionic halide compounds such as trans-2,3-Dibromo-2-butene-1,4-diol; meso-2,3-Dibromosuccinic acid; 5-Bromosalicylic acid; 3,5-Dibromosalicylic acid and other water-soluble mono and dibromo compounds. Additional examples of carboxylic acids and other activators suitable for inclusion in the flux are described in U.S. Pat. No. 5,297,721, and in U.S. Pat. No. 5,571,340, both of which are herein incorporated by reference in their entirety.
Surface wetting may be promoted by the addition of one or more anionic surfactants or other water-soluble surface-active agents. Examples of suitable surface-active agents include fluorinated surfactants as well as nonionic, cationic and amphoteric surfactants. Fluorinated surfactants as a class are powerful surface active agents, effective at very low concentrations. In practice, the surfactant is generally present in a concentration less than 2.0%, by weight, of the flux; and, in a preferred embodiment, the surfactant concentration is not more than 1.0%, by weight, of the flux. The concentration of the surfactant should enable the flux to thoroughly wet the surfaces to be soldered, while not contributing substantially to the level of flux residues that will be left behind after soldering. Nonionic, cationic and amphoteric surfactants can also be used. Together, the activator system and surfactants clean the surfaces to which flux is applied.
The soldering flux can additionally comprise small amounts of ingredients that enhance various properties and do not materially affect the basic properties of the flux. Such ingredients include, but are not limited to, biocides, corrosion inhibitors, dyes, foaming agents, de-foaming agents and stabilizers. The aggregate concentration of these additional ingredients is generally less than 1% by weight of the flux. The use of such ingredients is well known to those skilled in the art.
In a soldering process, leads of leaded electrical components are passed through holes in the board and placed in contact with conductive contacts on the other side of the board, and/or lead less chip components are mounted on the bottom side of the board with an adhesive. The soldering flux can then be applied to the board by spray or wave methods. The flux is applied so as to coat the surface of the board and to remove oxides and prevent cleaned metallic surfaces from re-oxidation and hence prepare the surfaces to be joined to produce defect-free solder joints. During pre-heat, the water component of the flux is evaporated; and during soldering, the resin emulsion breaks down and forms a hard, non-tacky, hydrophobic resinous layer that encapsulates the ionic activator residues. The result is a flux coating or fihn with high surface insulation resistance, which promotes the reliability of electrically conductive solder connections. This process is similar to that used with conventional solvent-based RMA, rosin-mild-activated, and RA, rosin-activated, type fluxes.


The present invention relates to a powder mixture for resorbable calcium phosphate biocements, which mixture consists of 40–99% by volume of powder having a particle size of 0.1–10 μm, 1–20% by volume of powder having a particle size of 10–43 μm and 0–59% by volume of powder having a particle size of 43–315 μm, which powder is obtained by grinding the spontaneously crystallizing melts of a material comprising crystalline and X-ray amorphous phases, which material                a) according to 31P-NMR measurements, contains Q0-groups of orthophosphate and Q1-groups of diphosphate, the orthophosphates or Q0-groups making up 65 to 99.9% by weight relative to the total phosphorus content of the powder mixture and the diphosphates or Q1-groups making up 0.1 to 35% by weight relative to the total phosphorus content of the powder mixture, and        b) according to X-ray diffractometric measurements and relative to the total weight of the powder mixture, contains 35 to 99.9% by weight of a main crystal phase consisting of various Ca-orthophosphates and 0.1 to 20% by weight of a secondary crystal phase consisting of various Ca-diphosphates and chain phosphates, and        c) besides the main crystal phase, contains an X-ray amorphous phase which in total makes up 0.1 to 65% by weight relative to the total weight of the powder mixture.

1. Field of the Invention
The present invention relates to powder mixtures based on calcium phosphates. The invention also relates to the use of the aforesaid powder mixtures for manufacturing biocements with high solubility which only contain the crystal phases currently known after setting, i.e. hydroxyapatite (HA), precipitated apatite (PHA) and calcium-deficient hydroxyapatite (Ca-d-HA), in subordinate amounts, i.e. as secondary phases.
2. Description of the Related Art
In principle, inorganic materials which are easily resorbed are known. Materials which are specifically used as bioactive bone replacement materials and dissolve quickly have also been described in the relevant literature. For example, there have been numerous publications dedicated to the successful clinical use of ceramic materials the main crystal phases of which are alpha- or beta-tricalcium phosphate (TCP). In addition, there have been comparative analyses of these two TCP phases using animal tests. With regard to the following explanations, special attention must be drawn to an alpha-TCP containing dicalcium phosphate on the surface of granulated materials made thereof, whose solubility was higher than that of the pure alpha-PCT core material, especially in the initial phase following an implantation (EP 0237043 B1).
The chemical solubility of the aforesaid granulated materials was surpassed by other bioactive materials based on calcium phosphates which in addition contain oxides of potassium, sodium, magnesium and/or silicon (EP 541564 B1) and the glassy-crystalline material of which is based on the following main crystal phases: Phase X, rhenanite, phase according to Ando (Phase A) and/or mixed crystals derived from the aforesaid phases.
The aforesaid products are obtained by melting processes, they contain orthophosphates and a glass phase and their individual phase constituents are distributed in a homogenous manner, but they are not known to have been processed into cements.
Instead, inorganic biocements have been composed using powder mixtures made up of various calcium phosphates, as disclosed e.g. in EP 1153621 or U.S. Pat. No. 5,129,905.

Powder mixture for resorbable calcium phosphate biocements

BAM Bundesanstalt für Materialforschung und -prüfung