Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/49—Phosphorus-containing compounds
  • C08K5/51—Phosphorus bound to oxygen
  • C08K5/53—Phosphorus bound to oxygen bound to oxygen and to carbon only
  • C08K5/5317—Phosphonic compounds, e.g. R—P(:O)(OR')2
  • C08K5/5333—Esters of phosphonic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
  • C08G59/4071—Curing agents not provided for by the groups C08G59/42 - C08G59/66 phosphorus containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/50—Amines
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/68—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used
  • C08G59/686—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used containing nitrogen
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/03—Use of materials for the substrate
  • H05K1/0313—Organic insulating material
  • H05K1/032—Organic insulating material consisting of one material
  • H05K1/0326—Organic insulating material consisting of one material containing O
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/03—Use of materials for the substrate
  • H05K1/0313—Organic insulating material
  • H05K1/0353—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement
  • H05K1/0373—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement containing additives, e.g. fillers

Definitions

• the present invention relates to curable epoxy-resin- containing formulations, and particularly to formulations useful for making laminates for printed wiring boards .
• an epoxy-containing formulation is applied to a substrate by rolling, dipping, spraying, other known techniques and/or combinations thereof.
• the substrate is typically a woven or nonwoven fiber mat containing, for instance, glass fibers.
• the impregnated substrate is "B-staged” by heating at a temperature sufficient to draw off solvent in the epoxy formulation and optionally to partially cure the epoxy formulation, so that the impregnated substrate can be handled easily.
• the "B-staging” step is usually carried out at a temperature of from 90°C to 210°C and for a time of from 1 minute to 15 minutes.
• the impregnated substrate that results from B-staging is called a prepreg.
• the temperature is most commonly 100°C for composites and 130°C to 200°C for electrical laminates .
• One or more sheets of prepreg are stacked in alternating layers with one or more sheets of a conductive material, such as copper foil, if an electrical laminate is desired.
• a conductive material such as copper foil
• the laid-up sheets are pressed at high temperature and pressure for a time sufficient to cure the resin and form a laminate.
• the temperature of lamination is usually between 100°C and 230°C, and is most often between 165°C and 190°C.
• the lamination step may also be carried out in two or more stages, such as a first stage between 100°C and 150°C and a second stage at between 165°C and 190°C.
• the pressure is usually between 50 N/cm 2 and 500 N/cm 2 .
• the lamination step is usually carried on for from 1 to 200 minutes, and most often for 45 to 90 minutes.
• the lamination step may optionally be carried out at higher temperatures for shorter times (such as in continuous lamination processes) or for longer times at lower temperatures (such as in low energy press processes) .
• the resulting copper-clad laminate may be post-treated by heating for a time at high temperature and ambient pressure.
• the temperatures of post-treatment are usually between 120°C and 250 °C.
• the post-treatment time usually is between 30 minutes and 12 hours .
• halogen containing fire-retardant additives are effective, they are considered by some to be undesirable from an environmental standpoint, and in recent years there has been increasing interest in the formulation of halogen-free epoxy resins, which are able to meet the fire retardancy requirements .
• Proposals have been made to use phosphorus based flame retardants instead of halogenated fire retardants (see, for example EP-A-0384939, EP-A-0384940 , EP-A-0408990 , DE-A-4308184, DE-A-4308185, DE-A-4308187 , WO-A-96/07685 , and WO-A-96/07686.
• the phosphorus flame retardant was pre-reacted to form a di or multifunctional epoxy resin. This makes the epoxy resin relatively expensive.
• the phosphonic acid esters are commercially available fire retardant materials (e.g., AmgardTM V19 and AmgardTM P45 - supplied by Albright and Wilson Ltd, United Kingdom) . These phosphonic acid esters, may be solids or liquids. Alkyl and aryl substituted phosphonic acid esters are compatible with epoxy resins. In particular lower (i.e., C ⁇ -C ) alkyl esters of phosphonic acid are of value because they contain a high proportion of phosphorus, and are thus able to impart good fire retardant properties upon resins in which they are incorporated.
• EP-A-0754728 describes the production of flame retardant epoxy resin systems by blending epoxy resins with phosphonic acid esters and incorporating them into the cured resin. This reference indicates that large quantities (in excess of 18 weight percent) of the phosphorus additive are needed in order for the resin system to meet UL 94 V-0.
• a flame retardant epoxy resin composition containing no more than 10% by weight of halogen comprising
• an epoxy resin b) a phosphonic acid ester in an amount such as to provide from 0.2 to 5 weight percent phosphorus in the composition, c) a nitrogen-containing crosslinking agent having an amine functionally of at least 2, in an amount of from 10 to 80 percent of the stoichiometric amount needed to cure the epoxy resin, d) from 0.1 to 3 weight percent of a catalyst capable of promoting the reaction of the phosphonic acid ester with the epoxy resin and promoting the curing of the epoxy resin with the crosslinker, and optionally, e) a Lewis acid in an amount of up to 2 moles, per mole of catalyst.
• the phosphonic acid ester employed in the present invention is preferably an ester of the formula .0— R2
• R 1 is C 1 to C 3 alkyl
• R 4 is C j to C 3 alkylene
• R 2 , and R 3 are each C 1 to C 3 alkyl, or C 6 to C 10 aryl, or R 2 and R 3 taken together represent the residue of a glycol or a polyol .
• Preferred phosphonic acid esters are for example esters of methanephosphonic acid with polyhydroxy compounds such as glycols, and polyols .
• Such phosphonic acid esters of polyhydroxy compounds can have polymeric and/or cyclic structures.
• polymers with repeating units such as :
• n 2 to 10
• R 5 is a C x to C 3 alkylene group or the residue of a glycol or polyol ,
• R6— 0 — P— O— R6-0 R is the residue of a triol, for example glycerol or trimethylol propane .
• the phosphonic acid ester is preferably an ester having methyl or methylene adjacent to phosphorous.
• Preferred phosphonic acid esters are those of the formula,
• the amount of the phosphonic acid ester is from 1 to 18 weight percent, preferably from 4 to 15 weight percent, more preferably from 7 to 15 weight percent, based on the total of the epoxy resin composition.
• the phosphonic acid ester content is preferably such as to provide a total phosphorous content in the composition, of from 0.2 to 5 weight percent, more preferably from 1 to 5 weight percent.
• compositions of the invention contain a catalyst capable of promoting the reaction of the phosphonic acid ester with the epoxy resin and promoting the curing of the epoxy resin.
• the catalyst may comprise a single catalyst component, capable both of promoting the reaction of the phosphonic acid ester with the epoxy resin and of promoting the curing of the epoxy resin.
• the catalyst may be a combination of components which favor one aspect of the resin curing over another.
• Suitable catalyst materials include compounds containing or amine, phosphine, ammonium, phosphonium, arsonium or sulfonium moieties.
• Particularly preferred catalysts are the heterocyclic nitrogen containing compounds.
• a Lewis acid is also employed, especially when the catalyst is an amine, particularly a heterocyclic nitrogen containing amine.
• Catalysts (as distinguished from cross-linkers) preferably contain on average no more than about 1 active hydrogen moiety per molecule. Active hydrogen moieties include hydrogen atoms bonded to an amine group, a phenolic hydroxyl group, or a carboxylic acid group.
• the amine and phosphine moieties in catalysts are preferably tertiary amine or phosphine moieties; and the ammonium and phosphonium moieties are preferably quaternary ammonium and phosphonium moieties .
• tertiary amines that may be used as catalysts are those mono- or polyamines having an open-chain or cyclic structure which have all of the amine hydrogen replaced by suitable substituents, such as hydrocarbyl radicals, and preferably aliphatic, cycloaliphatic or aromatic radicals.
• amines examples include, among others, , methyl diethanol amine, triethylamine, tributylamine, dimethyl benzylamine, triphenylamine, tricyclohexyl amine, pyridine and quinoline.
• Preferred amines are the trialkyl, tricycloalkyl and triaryl amines, such as triethylamine, triphenylamine, tri-(2,3- dimethylcyclohexyl) amine, and the alkyl dialkanol amines, such as methyl diethanol amines and the trialkanolamines such as triethanolamine.
• tertiary amines for example, amines that in aqueous solutions give a pH less than 10 in aqueous solutions of 1 M concentration, are particularly preferred.
• Especially preferred tertiary amine catalysts are benzyldimethylamine and tris- (dimethylaminomethyl ) phenol .
• heterocyclic nitrogen catalysts examples include those described in US-A-4 , 925 , 901.
• Preferable heterocyclic secondary and tertiary amines or nitrogen-containing catalysts which can be employed herein include, for example, imidazoles, benzimidazoles, imidazolidines , imidazolines , oxazoles, pyrroles, thiazoles, pyridines, pyrazines, morpholines, pyridazines, pyrimidines, pyrrolidines , pyrazoles, quinoxalines, quinazolines, phthalozines, quinolines, purines, indazoles, indoles, indolazines, phenazines, phenarsazines, phenothiazines, pyrrolines, indolines, piperidines, piperazines and combinations thereof.
• alkyl-substituted imidazoles 2 , 5-chloro-4-ethyl imidazole; and phenyl-substituted imidazoles, and mixtures thereof.
• N-methylimidazole 2-methylimidazole; 2-ethyl-4-methylimidazole; 1, 2-dimethylimidazole; and 2- methylimidazole.
• 2-phenylimidazole is especially preferred.
• heterocyclic nitrogen donor compounds which are preferably used in combination with Lewis acids are those described in EP-A-526488, EP-A-0458502- & GB-A-9421405.3. In these references the Lewis acids are described as inhibitors because they reduce the initial rate of the chemical reaction.
• Lewis acids examples include halides, oxides, hydroxides and alkoxides of zinc, tin, titanium, cobalt, manganese, iron, silicon, aluminium, and boron, for example Lewis acids of boron, and anhydrides of Lewis acids of boron, for example boric acid, metaboric acid, optionally substituted boroxines (such as trimethoxyboroxine) , optionally substituted oxides of boron, alkyl borates, boron halides, zinc halides (such as zinc chloride) and other Lewis acids that tend to have a relatively weak conjugate base.
• Lewis acids of boron for example boric acid, metaboric acid, optionally substituted boroxines (such as trimethoxyboroxine) , optionally substituted oxides of boron, alkyl borates, boron halides, zinc halides (such as zinc chloride) and other Lewis acids that tend to have a relatively weak conjugate base.
• the Lewis acid is a Lewis acid of boron, or an anhydride of a Lewis acid of boron, for example boric acid, metaboric acid, an optionally substituted boroxine (such as trimethoxy boroxine, trimethyl boroxine or triethyl boroxine) , an optionally substituted oxide of boron, or an alkyl borate .
• the most preferred Lewis acid is boric acid.
• Lewis acids are very effective in curing epoxy resins when combined with the heterocyclic nitrogen containing compounds, referred to above. In particular, they are able to incorporate the phosphonic acid ester into the epoxy resin during curing .
• the Lewis acids and amines can be combined before mixing into the formulation or by mixing with the catalyst in-situ, to make a curing catalyst combination.
• the amount of the Lewis acid employed is preferably at least 0.1 moles of Lewis acid per mole of heterocyclic nitrogen compound, more preferably at least 0.3 moles of Lewis acid per mole of heterocyclic nitrogen compound.
• the formulation preferably contains no more than three moles of Lewis acid per mole of catalyst and more preferably contains no more that 2 moles of Lewis acid per mole of catalyst.
• the total amount of the catalyst is from 0.1 to 3 weight percent, based on the total weight of the composition, preferably from 0.1 to 2 percent.
• the nitrogen-containing crosslinking agent has an amine functionality of at least 2. Suitable multifunctional crosslinkers are described in numerous references such as Vol . 6 Encyclopaedia of Poly. Sci. & Eng., "Epoxy resins" at 348-56 (J. Wiley & Sons 1986).
• nitrogen-containing cross-linkers examples include polyamines, polyamides, sulphanilamide, diaminodiphenylsulfone and diaminodiphenyl methane.
• the preferred crosslinking agent is dicyandiamide .
• the amount of the nitrogen-containing crosslinking agent is from 10 to 80 percent of the stoichiometric quantity needed to cure the epoxy content of the epoxy resin in the formulation.
• the total amount of nitrogen in the composition is preferably from 1 to 8 percent by weight.
• the quantity of nitrogen-containing cross-linking agent is preferably such that the formulation contains a stoichiometric excess of epoxy resin over the nitrogen-containing cross-linking agent.
• dicyandiamide is taken as having 6 curing sites per molecule.
• the formulation thus contains no more than 0.8 equivalents, preferably no more than 0.75, more preferably no more than 0.6, and most preferably no more than 0.5 equivalents of nitrogen-containing cross-linking agent per epoxide equivalent.
• the formulation preferably contains at least 0.65 weight percent and more preferably at least 1.9 weight percent of dicyandiamide.
• the amount of dicyandiamide is preferably no more than 5.2 weight percent and more preferably no more than 2.6 weight percent .
• the epoxy resin used in the present invention is a material which possesses on average more than 1 and preferably at least 1.8, more preferably at least 2 epoxy groups per molecule.
• the epoxy resin may be any saturated or unsaturated aliphatic, cycloaliphatic, aromatic or heterocyclic compound which possesses more than one 1,2-epoxy group.
• heterocyclic epoxy compounds are diglycidylhydantoin or triglycidyl isocyanurate (TGIC) .
• the epoxy resin is preferably one which has no lower alkyl aliphatic substituents, for example the glycidyl ether of a phenol novolac, or the glycidyl ether of bisphenol-F.
• epoxy novolac resins sometimes referred to as epoxidised novolac resins, a term which is intended to embrace both epoxy phenol novolac resins and epoxy cresol novolac resins.
• epoxy novolac resins sometimes referred to as epoxidised novolac resins, a term which is intended to embrace both epoxy phenol novolac resins and epoxy cresol novolac resins.
• Such compounds have the following general formula :
• R is hydrogen or a C1-C3 alkyl, e.g., methyl and "n” is 0 or an integer from 1 to 10.
• Epoxy novolac resins are readily commercially available, for example under the trade names D.E.N.TM, QuatrexTM, TactixTM, (Trademarks of The Dow Chemical Company) .
• the materials of commerce generally comprise mixtures of various species of the above formula and a convenient way of characterizing such mixtures is by reference to the average, n' , of the values of n for the various species.
• Preferred epoxy novolac resins for use in accordance with the present invention are those in which n' has a value of from about 2.05 to about 10, more preferably from about 2.5 to about 5.
• the epoxy resin is the reaction product of an epoxy compound containing at least two epoxy groups for example an epoxy compound of the kind describe above, and a chain extender.
• the chain extending monomer may be a phenolic chain extender containing on average more than one, and less than three phenolic hydroxyl groups per molecule.
• Such phenolic chain extenders preferably contain on average 1.8 to 2.1 phenolic hydroxyl groups and more preferably contains about 2 phenolic hydroxyl groups per molecule.
• the phenolic chain extender is preferably a dihydric phenol.
• the chain extender is preferably reacted with the epoxy compound to form the epoxy resin before formulation of the composition with the flame retardant, hardener and the catalyst.
• the epoxy resin is preferably one which is solid at 20 degrees C, for example one which has a softening point of
• the phenolic chain extender may itself be the reaction product of a diol and an epoxy compound.
• it may be the reaction product of a diol or a compound containing two phenolic groups, with a glycidyl ether of a phenol novolac or with a glycidyl ether of bisphenol-F.
• a glycidyl ether of a phenol novolac or with a glycidyl ether of bisphenol-F.
• less than 50 percent of the carbon atoms in the chain extender are present in aliphatic groups, more preferably less than 30 percent, and most preferably 0 percent.
• phenolic chains extenders examples include resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1, 1-bis (4-hydroxylphenyl) -1- phenylethane) , bisphenol F, and bisphenol K.
• the chain extender is a nitrogen-containing monomer for example, an isocyanate, and amine or amide.
• Preferred nitrogen-containing chain extenders include, polyisocyanate compounds which form epoxy-terminated polyoxazolidones as described in US-A-5, 112 , 932.
• the polyisocyanate compound used in the present invention is methylene bis (phenylisocyanate) (MDI) .
• MDI is preferably employed in its commercially available form, which includes, pure 4-4, MDI, isomers and functional homolog mixtures (commonly designated as "polymeric MDI”) .
• Isocyanate compounds also useful in the present invention include, for example, toluene diisocyanate (TDI) and isomers thereof .
• the nitrogen-containing chain extender may also be, for example an amine- or amino amide-containing compound which forms epoxy-terminated amine compounds having two N-H bonds capable of reacting with an epoxy group.
• Amine-containing compounds useful in the present invention include, for example, mono-primary amines of the general formula R-NH2 wherein R is alkyl, cycloalkyl or aryl moieties; di-secondary amines of the general formula R-NH-R' -NH-R" wherein R, R' and R" are alkyl, cycloalkyl or aryl moieties; and heterocyclic di-secondary amines wherein one or both of the N atoms is part of a nitrogen containing heterocyclic compound such as:
• di- secondary amines or primary amines having sterically hindered amine groups are preferred as for example 2,6-dimethyl eyelohexylamine or 2,6-xylidine (l-amino-2 , 6-dimethylbenzene) .
• Amino amide-containing compounds useful as chain extenders in the present invention include for example derivatives of carboxylic acid amides as well as derivatives of sulfonic acid amides having additionally one primary or two secondary amino groups .
• Preferred examples of such compounds are amino-aryl carboxylic acid amides and amino-arylsulfonamides .
• a preferred compound of this group is, for example, sulfanilamide (4-amino benzenesulfonamide) and anthranilamide (2-aminobenzamide) .
• the amount of the chain extender is preferably from 5 to 30 weight percent, based on the epoxy resin.
• compositions of the invention may also contain one or more additional flame retardant additives, for example red phosphorous or liquid or solid phosphorus containing compounds, for example, ammonium polyphosphate, a phosphite, or 9 , 10-dihydro-9-oxa- phosphaphenanthrene-10-oxide (HCA) , phosphazenes , nitrogen containing fire retardants and/or synergists, for example melamines, urea, cynamide, guanidine, cyanuric acid, isocyanuric acid and derivatives of those nitrogen containing compounds, halogenated flame retardants, halogenated epoxy resins (especially brominated epoxy resins) synergistic phosphorus-halogen containing chemicals or compounds containing salts of organic acids, inorganic metal hydrates, boron or antimony.
• additional flame retardant additives for example red phosphorous or liquid or solid phosphorus containing compounds, for example, ammonium polyphosphate, a
• compositions of the invention can be produced by mixing all the components together in any order.
• compositions of the invention can be produced by preparing a first composition comprising the epoxy resin, and the second composition comprising the curing catalyst.
• Either the first or the second composition also comprises the phosphonic acid ester, nitrogen- containing crosslinking agents. All other components may be present in the same composition, or some may be present in the first, and some in the second.
• the first composition is then mixed with the second composition, and cured to produce a fire retardant epoxy resin.
• reaction temperature rose to at least 150 °C by the heat of reaction.
• reaction mixture was increased to 165°C and maintained until the target epoxy equivalent weight of the copolymer of MDI and epoxy novalac resin was reached.
• the solid resin was further diluted with methylethylketone and propylene glycol monomethyl ether () (50/50) to a 80 weight percent solid solution and cooled to room temperature .
• a phosphonic acid ester fire retardant (Amgard P45 or
• Amgard V19 was heated to 120°C under nitrogen purge in a reactor equipped with an electrically driven mechanical stirrer, air and nitrogen inlets, sample port, condenser and thermocouple. Dicyandiamide or sulfanilamide was added and stirred until homogeneous mixture was obtained. Propylene glycol monomethyl ether was added to the mixture to make an 80 weight percent solids solution. Optionally the insoluble fire retardant additives were added to the hardener solution before adding it to the resin solution.
• Example 1 Preparation of "resin B” Boric acid in methanol was added to the D.E.N. 438/MDI copolymer. When the mixture was complete the phosphosphoric acid ester Amgard V19 ) flame retardant was mixed into the resin. 2-methylimidazole catalyst was added the resin solution. Lastly the dicyandiamide (7.5 weight percent in a 50/50 mixture of dimethylformamide and propylene glycol mono methyl ether was mixed in. The composition of the formulation and the properties of the formulation, prepregs and laminates made therefrom are given in the following table.
• the epoxy resin solution, the hardener solution, the catalyst solution (usually 50 weight percent solution in methanol) and optionally boric acid solution were mixed at room temperature with a mechanical stirrer for 15 minutes to make a homogeneous mixture. Additional solvents (methylethylketone) was added to adjust the varnish viscosity to 30-50 sec. on Ford cup N° 4. The varnishes were aged overnight . The varnishes were used to impregnate glass web (style Nr. 7628/36 amine silane finish by Porcher SA, France) , using a Caratsch pilot treater (3 m long) . The temperature of the hot air in the oven was 160-170°C.
• the varnish composition, treater condition, prepreg and laminate performance are summarized in Tables 1, 2, 3 and 4.
• the IPC test methods employed are the electrical laminate industry standard (The Institute For Interconnection And Packaging Electronic Circuits, 3451 Church Street, Evanston, Illinois 60203), as follows.
• Table 1 Formulations composition, properties, prepreg and laminate performance
• Table 2 Formulation compositions, properties, prepreg and laminate performance
• Table 3 Varnish compositions, properties, prepregs and laminates performance obtained from 2-methylimidazole catalysed system.
• Table 4 Formulation compositions, properties, prepreg and laminate performance of filler containing systems

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• 1997
  • 1997-06-26 GB GBGB9713526.3A patent/GB9713526D0/en not_active Ceased
• 1998
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  • 1998-06-25 JP JP50588699A patent/JP2002506480A/ja active Pending
  • 1998-06-25 EP EP98934218A patent/EP0991711A1/de not_active Withdrawn
  • 1998-06-25 WO PCT/US1998/013618 patent/WO1999000451A1/en not_active Application Discontinuation
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