CN1267314A - Flame Retardant Epoxy Resin Composition - Google Patents

Abstract

Novel epoxy resins having reduced flammability are described. Phosphonate is used in an amount to ensure that the content of phosphorus element in the epoxy resin is 0.2 to 5 weight percent. Electronic circuit laminates having reduced flammability may be made from such compositions.

Description

Flame Retardant Epoxy Resin Composition

The present invention relates to curable formulations containing epoxy resins, especially formulations useful in the manufacture of laminates for printed wiring boards.

Electronic laminates and other composites are known to be made from fiber reinforcements and epoxy-containing resin matrices. Examples of applicable methods typically have the following steps:

(1) Apply the formulation system containing the epoxy group to the substrate by roller coating, dip coating, spray coating, other known techniques and/or a combination of these techniques. Typically, the substrate is a woven or nonwoven fibrous mat, such as a mat containing glass fibers.

(2) Heating the impregnated substrate at a temperature sufficient to remove the solvent in the epoxy system and optionally partially cure the epoxy system, the impregnated substrate is "B-staged" ”, so that the impregnated substrate is easy to handle. The "B-staging" step is generally performed at 90°C to 210°C with a heating time of 1 minute to 15 minutes. After the B stage, the impregnated substrate is called a prepreg. In general, the heating temperature for composite materials is 100°C, and the heating temperature for electronic laminates is 130°C to 200°C.

(3) If it is desired to make an electronic laminate, one or more layers of prepreg and one or more layers of conductive materials, such as copper foil, are stacked in alternate layers.

(4) Press the laminated prepreg under high temperature and pressure for a time sufficient to cure the resin and form a laminate. The lamination temperature is usually between 100°C and 230°C, and the most commonly used temperature range is between 165°C and 190°C. The lamination molding process can also be divided into two or more stages, for example, the first stage is between 100°C and 150°C, and the second stage is between 165°C and 190°C. The pressure is usually between 50 N/cm2 and 500 N/cm2. The lamination process typically takes between 1 minute and 200 minutes, most often between 45 minutes and 90 minutes. The lamination process can be completed at a higher temperature in a shorter period of time (such as continuous lamination), or at a lower temperature in a longer period of time (such as a low-energy pressing process) .

(5) Optionally, the obtained copper-clad laminate can be heated at high temperature and ambient pressure for a period of time for post-treatment. The post-treatment temperature is usually carried out between 120°C and 250°C. Post-treatment times are typically 30 minutes to 12 hours.

Usually, various additives are added to the epoxy resin composition in order to improve the flame retardancy of the laminated board produced when preparing the laminated board containing epoxy groups. There are many kinds of flame retardant additives, but the most widely used additives in commerce are halogen-containing flame retardant additives, such as tetrabromodihydroxyphenyl propane, or diglycidyl ether of bisphenol A and tetrabromodihydroxyphenyl Epoxy resins prepared by the reaction of propane. Generally, in order to achieve the required flame retardancy level (the V-0 level of the test method UL94 of the standard "Underwriters Laboratory"), the required content of this type of compound should be able to provide 20% of the total weight of the polymer in the product. 10wt%-25wt% bromine content.

Although effective, halogen-containing flame retardant additives have been considered undesirable from an environmental standpoint, and in recent years there has been increasing interest in halogen-free epoxy resin systems that can meet flame retardant requirements.

Phosphorus-based flame retardants have been proposed to replace halogenated flame retardants (e.g. 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). In these systems, the phosphorus-containing flame retardant is pre-reacted to form a difunctional or multifunctional epoxy resin, which makes the epoxy resin relatively expensive.

Phosphonates are commercially readily available flame retardant materials (eg Amgard ^™ V19 and Amgard ^™ P45, supplied by Albright and Wilson Ltd, UK). These phosphonates can be solid or liquid. Alkyl and aryl substituted phosphonates are compatible with epoxy resins. Especially the lower (ie C ₁ -C ₄ ) alkyl esters of phosphonic acid, because they contain a relatively high proportion of phosphorus, can endow the added resin with better flame retardancy, so they have certain application value. However, the present inventors have found that they are not suitable as substitutes for halogenated flame retardants in epoxy resins in the manufacture of electronic circuit laminates, because they will cured After the epoxy resin is more likely to absorb moisture. The temperature absorption of cured laminates is very important, because laminates with high moisture content are prone to bubbles and scrap when immersed in liquid flux at about 260 ° C, and immersion in liquid flux is a typical process for manufacturing printed circuit boards. process.

EP-A-0754728 describes the production of flame retardant epoxy resin systems by mixing epoxy resin and phosphonate and incorporating the phosphonate into the cured resin. This reference states that in order for a resin system to meet the requirements of UL 94 V-0, large amounts (over 18 wt%) of phosphorus-containing additives are required.

We have now found that by using relatively low levels of phosphonate flame retardants (so that the solid resin contains 0.2 wt% to 5 wt% phosphorus), combined with a special combination of accelerators and catalysts, and in preferred embodiments, Also combined with certain types of epoxy resins, it is possible to produce epoxy resins that meet flame retardant standards without the need for halogen-containing flame retardants, or at least using much smaller amounts of halogen-containing flame retardants than conventionally used. Accelerators and catalysts are known per se, but they are used in combination with lower levels of phosphonate flame retardants to produce flame retardancy with sufficiently low water absorption. composition, has not been reported so far.

According to the present invention, there is provided a flame retardant epoxy resin composition containing no more than 10 wt% halogen, which contains:

a) epoxy resin,

b) phosphonates in an amount to provide 0.2% to 5% by weight of phosphorus in the composition,

c) nitrogen-containing cross-linking agents having an amine functionality of at least 2, used in amounts ranging from 10% to 80% of the stoichiometric amount required to cure the epoxy resin,

d) catalyst, its consumption is 0.1wt%～3wt%, it can accelerate the reaction speed of phosphonate and epoxy resin, can also accelerate the curing speed of epoxy resin and crosslinking agent, and optionally,

e) Lewis acids in amounts of up to 2 moles of Lewis acid per mole of catalyst.

其中R¹是C₁～C₃烷基，R⁴是C₁～C₃亚烷基，R²和R³各自是C₁～C₃烷基或C₆～C₁₀芳基，或者R²和R³合起来代表二醇或多元醇的残基。The phosphonates used in the present invention are preferably esters of the formula:

wherein R ¹ is a C ₁ to C ₃ alkyl group, R ⁴ is a C ₁ to C ₃ alkylene group, R ² and R ³ are each a C ₁ to C ₃ alkyl group or a C ₆ to C ₁₀ aryl group, or R ² and ^R together represent the residue of a diol or polyol.

Preferred phosphonates are, for example, esters of methanephosphonic acid with polyols, such as diols and polyols. Such polyol phosphonates may have a polymeric structure and/or a cyclic structure.

R⁶是三元醇例如丙三醇或三羟甲基丙烷的残基。Specific preferred examples are polymers having the following repeating units and/or have a ring structure as follows: n is 2 to 10, R ⁵ is a C ₁ to C ₃ alkylene group or a residue of a diol or a polyol,

^R6 is the residue of a trihydric alcohol such as glycerol or trimethylolpropane.

Preferred phosphonates are those having a methyl or methylene group adjacent to the phosphorus atom. Preferred phosphonates have the formula:

In order to obtain satisfactory anti-water absorption performance, it is important that, based on the total weight of the epoxy resin composition, the amount of phosphonate is 1wt% to 18wt%, preferably 4wt% to 15wt%, more preferably 7wt% to 15wt% . The amount of phosphonate preferably provides a phosphorus content of 0.2 wt% to 5 wt% in the composition, more preferably a phosphorus content of 1 wt% to 5 wt%.

The compositions of the present invention contain a catalyst which accelerates the reaction between the phosphonate ester and the epoxy resin and also increases the cure rate of the epoxy resin.

The catalyst can contain a single catalyst component, which can not only accelerate the reaction speed of phosphonate and epoxy resin, but also improve the curing speed of epoxy resin. Alternatively, the catalyst is a combination of components, each component of the catalyst catalyzing one aspect in which the resin cures more than another component in curing the resin.

Examples of suitable catalysts include compounds containing amine, phosphine or ammonium, phosphonium, potassium or sulfonium moieties. Particularly preferred catalysts are nitrogen-containing heterocyclic compounds. Especially when the catalysts are amines, preference is also given to using Lewis acids, especially nitrogen-containing heterocyclic amines. Preferably, the catalyst (as distinguished from the crosslinker) contains on average no more than about one active hydrogen moiety per molecule. Active hydrogen moieties include hydrogen atoms on amine groups, phenolic hydroxyl groups, or carboxylic acid groups. For example, preferred amine and phosphine moieties in the catalyst are tertiary amine or phosphine moieties, and preferred ammonium and phosphonium moieties are quaternary ammonium and phosphonium moieties.

Among the tertiary amines that can be used as catalysts, preference is given to monoamines or polyamines with open-chain or cyclic structures in which all hydrogen atoms are replaced by suitable substituents, such as hydrocarbyl groups, preferably aliphatic, Cycloaliphatic or aromatic groups.

Examples of such amines are methyldiethanolamine, triethylamine, tributylamine, dimethylbenzylamine, triphenylamine, tricyclohexylamine, pyridine and quinoline. Preferred amine compounds are trialkylamines, tricycloalkylamines, and triarylamines, such as triethylamine, triphenylamine, tris-(2,3-dimethylcyclohexyl)amine, and alkyldialkanolamines , such as methyldiethanolamine, and trialkanolamines, such as triethanolamine. Particularly preferred are weakly basic tertiary amines, for example amines having a pH of less than 10 in a 1M aqueous solution. Especially preferred tertiary amine catalysts are benzyldimethylamine and tris-(dimethylaminomethyl)phenol.

Examples of nitrogen heterocyclic compounds suitable for use as catalysts include those described in US-A-4925901. Preferred heterocyclic secondary and tertiary amines or nitrogen-containing catalysts that can be used herein include, for example, imidazole, benzimidazole, imidazolidine, imidazoline, oxazole, pyrrole, thiazole, pyridine, pyrazine, morpholine, pyridazine , pyrimidine, pyrrolidine, pyrazole, quinoxaline, quinazoline, phthalazine, quinoline, purine, indazole, indole, indoleamine, phenazine, phenpyrazine, phenothiazine, pyrroline, di Indoline, piperidine, piperazine, and combinations thereof. Particularly preferred are alkyl-substituted imidazoles; 2,5-chloro-4-ethylimidazoles; and phenyl-substituted imidazoles; and mixtures thereof. More preferred are N-methylimidazole; 2-methylimidazole; 2-ethyl-4-methylimidazole; 1,2-dimethylimidazole; and 2-methylimidazole. Especially preferred is 2-phenylimidazole.

Examples of nitrogen heterocyclic electron donating compounds preferably used in combination with Lewis acids are described in EP-A-526488, EP-A-0458502 and GB-A-9421405.3. In these references, the Lewis acid is considered to be an inhibitor because it reduces the initial chemical reaction rate. Examples of suitable Lewis acids include halides, oxides, hydroxides and alkoxides of zinc, tin, titanium, cobalt, manganese, iron, silicon, aluminum and boron, such as Lewis acids of boron and anhydrides of Lewis acids of boron , such as boric acid, metaboric acid, optionally substituted boroxine (such as trimethoxyboroxine), optionally substituted boron oxide, alkyl borate, boron halide, zinc halide (such as zinc chloride) , and other Lewis acids with relatively weak conjugate bases. Preferably, the Lewis acids are boron Lewis acids and boron Lewis anhydrides, such as boric acid, metaboric acid, optionally substituted boroxines (such as trimethoxyboroxine, trimethylboroxine, triethylboroxine, boroxine), an optionally substituted boron oxide, or an alkyl borate. The most preferred Lewis acid is boric acid.

These Lewis acids are very effective when used in combination with the nitrogen-containing heterocyclic compounds described above in curing epoxy resins. Especially during the curing process, they allow the phosphonate to be integrated with the epoxy resin.

To prepare the curing catalyst composition, the Lewis acid and amine can be combined prior to addition to the system or mixed in situ with the catalyst.

The preferred amount of Lewis acid is at least 0.1 moles of Lewis acid per mole of nitrogen heterocyclic compound, more preferably at least 0.3 moles of Lewis acid per mole of nitrogen heterocyclic compound.

Preferred systems have no more than 3 moles of Lewis acid per mole of catalyst, more preferably no more than 2 moles of Lewis acid per mole of catalyst. The total amount of the catalyst accounts for 0.1wt%-3wt% of the total weight of the composition, and the preferred amount is 0.1wt%-2wt%.

All of the catalyst materials mentioned above catalyze both the reaction of the phosphonate ester and the epoxy resin and the curing reaction of the epoxy resin to some extent. However, in the reaction between phosphonate and epoxy resin and the curing reaction of epoxy resin, (1,8-diazabicyclo(5,4,0)undec-7-ene (DBU) tends to The reaction of the phosphonate and epoxy is more catalytic.

The nitrogen-containing crosslinker has an amine functionality of at least two. Suitable polyfunctional crosslinkers are described in many references, such as "Encyclopedia of Polymer Science and Engineering", Volume VI, "Epoxy Resins", pp. 348-356 (J.Wiley & Sons 1986). Examples of suitable nitrogen-containing crosslinking agents include polyamines, polyamides, sulfanilamide, diaminodiphenylsulfone and diaminodiphenylmethane. A preferred crosslinking agent is dicyandiamide.

The amount of the nitrogen-containing crosslinking agent is 10% to 80% of the stoichiometric amount needed to cure the epoxy content in the epoxy resin in the system.

The preferred total content of nitrogen in the composition (including nitrogen from any nitrogen-containing compound, which may constitute part of the catalyst, or the precursor monomer of the epoxy resin) is 1 wt % to 8 wt %.

Preferably, in view of the stoichiometric ratio of epoxy resin and nitrogen-containing crosslinking agent, the system contains more than stoichiometric amount of epoxy resin. (For this reason, it is considered that there are 6 curing sites per molecule of dicyandiamide.) In this way, each epoxy equivalent contains no more than 0.8 equivalents of nitrogen-containing crosslinking agent in the system, preferably no more than 0.75 equivalents, more preferably No more than 0.6 equivalents, most preferably no more than 0.5 equivalents of nitrogen-containing crosslinking agent. When the polyfunctional crosslinking agent is dicyandiamide, more preferably, the system contains at least 0.65wt% of dicyandiamide, more preferably at least 1.9wt%. The preferred amount of dicyandiamide is not more than 5.2 wt%, more preferably not more than 2.6 wt%.

In the present invention, the epoxy resin used contains on average more than 1 epoxy group per molecule, preferably at least 1.8, more preferably at least 2 epoxy groups. In the broadest scope of the invention, the epoxy resin may be any saturated or unsaturated aliphatic, cycloaliphatic, aromatic or heterocyclic compound containing more than one 1,2-epoxy group. Examples of heterocyclic epoxy compounds are diglycidyl hydantoin or triglyceryl isocyanurate (TGIC).

Preferably, the epoxy resin has no lower alkyl aliphatic substituents, such as the glycidyl ether of phenol novolac, or the glycidyl ether of bisphenol-F.

其中“R”是氢原子或C1-C3的烷基，如甲基，“n”是0或者1～10的整数。The most preferred epoxy resins are epoxy novolacs (sometimes referred to as epoxidized novolacs, a term that includes epoxy phenol novolacs and epoxy cresol novolacs). The general molecular formula of this compound is as follows: general formula II:

Wherein "R" is a hydrogen atom or a C1-C3 alkyl group, such as a methyl group, and "n" is an integer of 0 or 1-10.

Epoxy novolac resins (including epoxy cresol novolac resins) are readily available in the industry, for example, under the trade names of DEN ^™ , Quatrex ^™ , Tactix ^™ , (trademarks of DOW Chemical Company). Industrial materials usually include mixtures of various substances having the above formulas. A convenient way to characterize such mixtures is to quote the mean n' of the n values for the various species. Preferred epoxy novolac resins for use in the present invention have n' values from about 2.05 to about 10, more preferably n' values from about 2.5 to about 5.

A preferred epoxy resin is the reaction product of an epoxy compound containing at least 2 epoxy groups, such as the epoxy compounds described above, and a chain extender. The chain-extending monomer may be a phenolic chain-extending agent, and each molecule of the phenolic chain-extending agent contains more than one and no more than three phenolic hydroxyl groups on average. Preferred such phenolic chain extenders contain an average of 1.8 to 2.1 phenolic hydroxyl groups. More preferably, the phenolic chain extender has an average of about 2 phenolic hydroxyl groups per molecule. Preferred phenolic chain extenders are dihydric phenols. Preferably, the chain extender reacts with the epoxy compound to form an epoxy resin before the composition system containing the flame retardant, curing agent and catalyst is formed. However, chain extenders and epoxy resin compounds can also be added to the composition to form the epoxy resin in situ.

Preferred epoxy resins are solid at 20°C, for example, epoxy resins having a softening point of 50°C or higher, as defined by the Mettler softening point test method of ASTM D3104 and DIN 51920. As such, phenolic chain extenders can be the reaction product of diols and epoxides.

For example, it may be a reaction product of a diol or a compound containing two phenolic groups, with a glycidyl ether of a phenol novolac resin or with a glycidyl ether of bisphenol F. Preferably, less than 50% of the carbon atoms in the chain extender are on aliphatic groups, more preferably less than 30%, most preferably 0%.

Examples of particularly suitable phenolic chain extenders are resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1-bis(4-hydroxyphenyl)- 1-phenylethane), bisphenol F and bisphenol K.

More preferred chain extenders, however, are nitrogen containing monomers such as isocyanates, amines or amides.

Preferred nitrogen-containing chain extenders include polyisocyanate compounds which form epoxy-terminated polyoxazolidinones, as reported in US-A-5,112,932. Preferably, the polyisocyanate compound used in the present invention is diphenylmethane diisocyanate (MDI). Preferably, MDI can be used in the form readily available in industry, including pure 4-4, MDI, mixtures of isomers and functional homologues (generally referred to as "polymeric MDI"). Isocyanate compounds such as toluene diisocyanate (TDI) and its isomers may also be used in the present invention.

Nitrogen-containing chain extenders can also be, for example, compounds containing amine groups, or compounds containing aminoamides, which form epoxy-terminated amine compounds with two NH bonds capable of reacting with epoxy groups. Amino group-containing compounds suitable for use in the present invention include, for example, primary monoamines of the general formula R- _NH , wherein R is an alkyl, cycloalkyl or aromatic moiety; the general formula is R-NH-R'-NH Secondary diamines of -R", where R, R', R" are alkyl, cycloalkyl, or aromatic moieties; and secondary diamines of heterocyclic rings, where either or both N atoms are nitrogen-containing heterocyclic compounds part of , for example:

For reasons of reactivity, and in order to better control the early reaction of epoxy groups and difunctional amines, preferably, amine groups such as dibasic secondary amines and dibasic primary amines with steric hindrance effects are preferably used , such as 2,6-dimethylcyclohexylamine or 2,6-xylaniline (1-amino-2,6-dimethylbenzene).

In the present invention, the amino acid amide compound that can be used as a chain extender includes, for example, derivatives of carboxylic acid amides, and derivatives of sulfonic acid amides additionally having one primary amino group or two secondary amino groups. Preferred examples of these compounds are amino-aryl carboxylic acid amides and amino-aryl sulfonic acid amides. Preferred compounds of this type are, for example, sulfanilamide (4-aminophenylsulfonamide) and anthranilamide (2-aminobenzamide).

Preferably, the amount of the chain extender is 5wt%-30wt% of the epoxy resin.

The compositions of the present invention also contain one or more auxiliary flame retardants, such as red phosphorus, or liquid or solid phosphorus-containing compounds, such as ammonium polyphosphate, phosphite, or 9,10-dihydro-9-oxa - phosphaphenanthrene-10-oxides (HCA), phosphazenes, nitrogen-containing flame retardants and/or compatibility agents such as melamine, urea, cyanamide, guanidine, cyanuric acid, isocyanuric acid and those containing Derivatives of nitrogen compounds, halogenated flame retardants, halogenated epoxy resins (especially brominated epoxy resins), phosphorus-halogen synergistic systems containing organic acid salts, inorganic metal hydrates, boron or antimony compounds . Examples of suitable secondary flame retardants are presented in a paper in "Flame Retardants - 101 Fundamental Dynamics - Using the Efforts of the Past to Create Tomorrow's Opportunities", Flame Retardant Chemistry Society, Baltimore Marriot Inner Harbor Hotel, Baltimore, Maryland , March 24-27, 1996. When there is additional phosphorus-containing auxiliary flame retardant in the system, the amount thereof is usually such that the total content of phosphorus in the epoxy resin composition is 0.2wt%-5wt%.

The compositions of the present invention may be prepared by combining all ingredients in any order. Preferably, the composition of the present invention can be prepared by first preparing a first composition containing an epoxy resin, and then preparing a second composition containing a curing catalyst. A phosphonate and a nitrogen-containing crosslinker are also included in either the first composition or the second composition. All other ingredients may be present in the same composition, or some ingredients in the first composition and others in the second composition. The first composition is then mixed with the second composition to form an epoxy resin with flame retardant properties after curing.

In the following specific examples, a number of preferred embodiments of the invention are illustrated. Preparation Method A General Production Process for Epoxy Resins (a) with Higher Nitrogen Contents

Under nitrogen blanket, 92.5 parts by weight of an industrially producible epoxy novolac resin with a functionality of 3.6 was introduced in a reactor equipped with an electric stirrer, air and nitrogen inlets, sampling ports, condenser and thermocouple (DEN438) heated to 100°C. (Based on the total amount of epoxy novolac resin and isocyanate in the product) add 1500ppm of 1,8-diazabicyclo (5,4,0) undec-7-ene (reaction catalyst, AMICURE BU-E ^TM , produced in Anchor), the mixture was heated to 130°C to 140°C. 7.5 parts of MDI (ISONATE ^™ , DOW Chemical Co.) were added to the epoxy resin in portions through a separate funnel. Under the exotherm of reaction, the temperature of the reactants rises to at least 150°C. After the addition was complete, the temperature of the reaction mixture was raised to 165°C and maintained at this temperature until the epoxy equivalent weight of the MDI and epoxy novolac copolymer reached the desired target. The solid resin was further diluted with methyl ethyl ketone and propylene glycol monomethyl ether (50/50) to a solution with a solid content of 80 wt%, and then cooled to room temperature. General Production Process for Preparation Method B Curing Agent Solution

Phosphonate flame retardants (Amgard P45 or Amgard V19) were heated to 120 °C under nitrogen in a reactor equipped with an electromechanical stirrer, air and nitrogen inlets, sampling ports, condenser, and thermocouple. Add dicyandiamide and sulfanilamide to the mixture and stir until a homogeneous mixture is formed. Propylene glycol monomethyl ether was added to the mixture to obtain a solution with a solid content of 80 wt%. Alternatively, the insoluble flame retardant additive may be added to the curing agent solution before it is added to the resin solution. Production Process of Polyepoxide/Polyisocyanate/HCA Copolymer ("Resin A")

At about 160°C, 3.77 wt% of 9,10-di-hydro-9-oxa-phosphaphenanthrene-10-oxide (HCA) was added to 96.23 wt% of the solid ring prepared by Preparation A In the epoxy resin, keep warm until the epoxy equivalent reaches the expected target of 232. The solid was cooled to about 130 °C, and methyl ethyl ketone and propylene glycol monomethyl ether (50/50) were added to form a solution with a solid content of 75 wt%.

Example 1 - Preparation of "Resin B" Boric acid dissolved in methanol was added to a D.E.N. 438/MDI copolymer. When the mixture is fully mixed, the phosphonate (Amgard V19) flame retardant is added to the resin. The 2-methylimidazole catalyst was added to the resin solution. Finally, dicyandiamide (7.5% by weight solution in a 50/50 mixture of dimethylformamide and propylene glycol monomethyl ether) was added. In the table below, the constituents of the formulations, the properties of the system and the properties of the prepregs and laminates made therefrom are listed.

Preparation of Resins A and C to N

The epoxy resin solution, curing agent solution, catalyst solution (usually 50 wt% methanol solution), and optionally boric acid solution were mixed with a mechanical stirrer at room temperature for 15 minutes to form a homogeneous mixture. Add additional solvent (methyl ethyl ketone) and adjust the viscosity of the varnish to 30-50 seconds (No. 4 Ford Cup). Aging the varnish overnight.

The varnish was used to impregnate the glass fiber mats (type Nr. 7628/36, surface treated with aminosilane, produced by Porcher SA, France), using a Caratsch pilot dipping machine (3 m long). The temperature of the hot air in the oven is 160°C to 170°C. In Tables 1, 2, 3, 4, the clearcoat composition, dip coater conditions, prepreg and laminate properties are summarized.

As shown below, the IPC test method used is the Electronic Laminate Industry Standard (Electronic Circuit Interconnection and Packaging Association, 3451 Church Street, Evanston, Illinois 60203). method IPC-Test method number: Reactivity (varnish) IPC-TM-650-5.1.410 Static gel time 170°C, seconds IPC-TM-650-2.3.18 Mil flow, wt.% IPC-TM-650-2.3.17 Glass transition temperature, °C IPC-TM-650-2.4.25 Copper foil peel strength IPC-TM-650-2.4.8 NMP-Absorptive DOW test method C-TS-AA-1012.00 Autoclave test, water absorption wt.% and percentage of flux bath at 260°C IPC-TM-650-2.6.16 UL94 Flammability IPC-TM-650-2.3.10

Table 1 Composition Formulation, Properties, Prepreg and Laminate Properties Composition of solid parts by weight B C D. E. Resin produced by Preparation Method A 86 84 84 Epoxy novolak resin with a functionality of 3.6 85 Amgard V19 14 14 Amgard P45 14 14 Dicyandiamide (dissolved in Amgard V19 or Amgard P45) 2 (dissolved in Amgard P45) 2 (dissolved in Amgard V19) 2 (dissolved in Amgard P45) B boric acid 1 0.3 - 2-Phenylimidazole 1.7 2 1 2-Methylimidazole 1 Supplementary solvent MEK MEK MEK Dicyandiamide solution (7.5wt%) 1 Varnish properties Viscosity (Ford Cup 4#), second 76 38 126 36 Reactivity, seconds Gel time 170°C 150°C 85 102242 151 109322 Dip coating machine conditions Oven temperature, ℃ Lifting speed, m/min 1852.3 1681.4 1521.1 Prepreg Properties Resin content, wt% 41 43.4 45 42.6 Static gel time 170°C, seconds to melt 10 14 15 Mil flow.wt% 10 10.5 15 15.3 Laminate properties Laminate Cure Cycle 1 hour at 170°C 1 hour at 230°C 1 hour at 170°C 1 hour at 230°C 100 minutes at 200°C 90 minutes at 230°C 1 hour at 170°C 1 hour at 230°C Laminate thickness, mm 1.4-1.5 1.52-1.57 1.7-1.8 1.47-1.70 Glass transition temperature-Tg1/2, ℃ 158/159 158/162 149/146 not measured High-pressure cooking experiment, water absorption wt.%/percentage passing through 260°C flux bath wt%/% pass wt%/% pass wt%/% pass wt%/% pass 30 minutes 0.38/100 no data/100 0.53/100 40 minutes 50 minutes 0.53/100 60 minutes 0.64/100 0.60/100 Total burning time, seconds 69&35 36 30 46 UL94 V-1&V-0 V-0 V-0 V-0

Table 2 Composition Formulation, Properties, Prepreg and Laminate Properties Composition of solid parts by weight f G Resin A Resin produced by Preparation Method A 79.5 83.5 Resin SANKO/HCA produced by preparation method A 81.5 Amgard P45 14 14 12 Dicyandiamide (dissolved in Amgard P45) 2 Sulfuramide (dissolved in Amgard P45) 6 6 boric acid 0.5 0.5 0.5 2-Phenylimidazole 2.0 2.0 2.0 Supplementary solvent MEK MEK MEK Varnish properties Viscosity (Ford Cup 4#), seconds 45 39 45 Reactivity. Seconds Gel time 170°C 150°C 90240 87220 132--- Dip coating machine conditions Oven temperature, ℃ Lifting speed, m/min 1631.2 1631.1 1610.7 Prepreg Properties Resin content, wt% 45 44 45 Static gel time 170°C, seconds 8 10 twenty four Mil flow.wt% 13 15 twenty one Laminate Properties Laminate Cure Cycle 90 minutes at 190°C Laminate thickness, mm 1.6-1.7 1.6-1.8 1.57-1.70 Glass transition temperature-Tg1/2, ℃ 160/166 161/167 157/160 Copper foil peel strength N/cm 15.7 17.0 16.3 NMP-absorbability, % High-pressure cooking test, water absorption wt.% & percentage passing through 260°C flux bath wt%/% pass wt%/% pass wt%/% pass 40 minutes 0.52/100 0.6/75 0.53/100 60 minutes 0.64/75 0.75/75 0.69/50 Total burning time, seconds 53 47 34 UL94 V-1 V-0 V-0

 Table 3: Varnish compositions, characteristics, prepared by 2-methylimidazole catalyst system

Prepreg and Laminate Properties Composition of solid parts by weight I J Resin produced by Preparation Method A 85 86 Amgard V19 14 14 Dicyandiamide (dissolved in Amgard V19) 1 1 boric acid 1 - 2-Methylimidazole 1 1 Supplementary solvent MEK MEK Varnish Properties Viscosity (Ford Cup 4#), seconds 132 137 Reactivity, seconds Gel time 170°C 150°C 109178 70150 Dip coating machine conditions Oven temperature, ℃ Lifting speed, m/min 1600.8 1601.3 Prepreg Properties Resin content, wt% 45.1 41.2 Static gel time 170°C, seconds 0 9 Mil flow, wt% 17.0 18.0 Laminate properties Laminate Cure Cycle 90 minutes at 230°C Laminate thickness, mm 1.6-1.7 1.40-1.48 Glass transition temperature-Tg1/2, ℃ 166/169 143/148 High-pressure cooking test, water absorption wt.% & percentage passing through 260°C flux bath wt%/% pass wt%/% pass 40 minutes 0.57/100 0.55/100 60 minutes 0.77/0 0.75/0 Total burning time, seconds 54 49 UL94 V-1 V-0

Table 4: Composition formulations, properties, properties of prepregs and laminates containing filler systems Composition of solid parts by weight K L m Resin produced by Preparation Method A 84.00 84.00 74.50 Amgard P45 10.00 10.00 10.00 Dicyandiamide (soluble in P45) 2.00 2.00 P-Sulphonamide (Soluble in P45) 6.00 Hostaflam ^TM AP 423 Ammonium Polyphosphonate 5.00 7.00 Hostaflam TP RP 605 Red Phosphorus 1.50 max boric acid 0.5 0.5 0.5 2-Phenylimidazole 2.0 2.0 2.0 Supplementary solvent MEK/Dowanol PM MEK/Dowanol PM MEK/Dowanol PM Varnish properties Viscosity (Ford Cup 4#), second 120 63 60 Reactivity. Seconds Gel time 170°C 150°C 77 70 77 Dip coating machine conditions Oven temperature, ℃ Lifting speed, m/min 1571.3 1571.4 1571.5 Prepreg Properties Resin content, wt% 39.5 41 40.8 Static gel time 170°C, seconds twenty three 20 twenty three Mil flow, wt% 11.9 16.5 15.7 Laminate properties Laminate Cure Cycle 90 minutes at 190°C 90 minutes at 190°C 90 minutes at 190°C Laminate thickness, mm 1.45 1.55 1.45 Glass transition temperature-Tg1/2, ℃ 166.6/170.7 170.2/171.4 172.7/171.3 Copper foil peel strength N/cm 0.083 0.034 0.017 NMP-absorbability, % Autoclave test, water absorption wt.% and percentage of flux bath at 260°C wt%/% pass wt%/% pass wt%/% pass 60 minutes 100 100 50 75 minutes 50 100 50 90 minutes 0 50 Total burning time, seconds 32 29 26 UL94 V-0 V-0 V-0

Claims (29)

1. A flame-retardant epoxy resin composition containing not more than 10% by weight of halogen, comprising: a) epoxy resin; b) phosphonates in an amount capable of providing 0.2 to 5% by weight of phosphorus in the composition; c) a nitrogen-containing crosslinking agent having an amine functionality of at least 2 in an amount of 10 to 80% of the stoichiometric amount required to cure the epoxy resin; d) Catalyst, its consumption is 0.1～3wt%, both can accelerate the chemical reaction speed of phosphonate ester and epoxy resin, can improve the curing speed of epoxy resin and crosslinking agent again, and dispensable e) Lewis acids in amounts not to exceed 2 moles of Lewis acid per mole of catalyst. 2. The composition of claim 1, wherein the epoxy resin has a softening point of at least 50°C (ASTM D3104). 3. The composition of claim 1 or 2, wherein the epoxy resin contains not more than two alkyl groups per molecule. 4. The composition of claim 3, wherein the epoxy resin contains no more than 1 alkyl group per molecule. 5. The composition of any one of the preceding claims, wherein the epoxy resin is the reaction product (or mixture) of a monomer containing at least two epoxy groups and a difunctional chain-extending monomer, or the composition also contains Additional difunctional chain extender monomer. 6. The composition of claim 5, wherein the difunctional chain-extending monomer is diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), 2,6-dimethylhexylamine, sulfanilamide or Anthranilamide. 7. The composition of claim 5 or 6, wherein the monomer containing at least two epoxy groups is a glycidyl ether of a phenol novolac resin, or a glycidyl ether of bisphenol-F. 8. A composition according to any one of the preceding claims, wherein the epoxy resin is used in an amount of 50 to 95% by weight of the composition, based on solids content. 9. A composition according to any one of the preceding claims, wherein the epoxy resin is used in an amount of 80 to 90% by weight of the composition based on solids content. 10. The composition of any one of the preceding claims, wherein the phosphonate is an ester having the formula: Wherein R ¹ is C ₁ ~ C ₃ alkyl, R ⁴ is C ₁ ~ C ₃ alkylene, R ² and R ³ are C ₁ ~ C ₃ alkyl or C ₆ ~ C ₁₀ aryl, or R ² and R ³ together represent the residue of a diol or polyol. 11. The composition of claim 10, wherein ^R1 is methyl, ^R4 is methylene, and ^R2 and ^R3 are each independently methyl, ethyl, phenyl, or hydroxyphenyl. 12. The composition of any one of the preceding claims, wherein the phosphonate is a compound of the formula: 13. A composition according to claim 11 or 12, wherein the phosphonate is present in an amount of 4% to 15% by weight of the composition. 14. The composition of claim 13, wherein the phosphonate is present in an amount of 7 to 15% by weight of the composition. 15. A composition according to any one of the preceding claims, wherein the phosphonate is used in an amount to provide from 0.5% to 5% by weight of phosphorus in the composition. 16. The composition of claim 15, wherein the phosphonate is used in an amount to provide from 1 wt% to 3.8 wt% phosphorus in the composition. 17. The composition of claim 16, wherein the phosphonate is used in an amount to provide 1.4 wt% to 3.1 wt% phosphorus in the composition. 18. The composition of any one of the preceding claims, wherein the nitrogen-containing crosslinking agent having an amine functionality of at least 2 is dicyandiamide, sulfanilamide, diaminodiphenylsulfone and/or diaminodiphenylmethane . 19. A composition according to any one of the preceding claims, wherein the total amount of nitrogen-containing crosslinkers in the composition does not exceed 80% of the stoichiometric amount required for reaction with the epoxy resin. 20. A composition as claimed in any one of the preceding claims, wherein the total amount of nitrogen-containing compounds in the composition is such as to provide a total nitrogen content of 1 to 8% of the composition. 21. A composition as claimed in any one of the preceding claims wherein the catalyst comprises a single catalyst component which both increases the rate of reaction of the phosphonate with the epoxy resin and increases the rate of cure of the epoxy resin. 22. The composition according to any one of claims 1 to 20, wherein the catalyst contains a catalyst component which plays a greater role in the reaction speed of the phosphonate ester and the epoxy resin and the curing speed of the epoxy resin. catalytic effect. 23. The composition of claim 22, wherein the catalyst composition is 1,8-diazabicyclo(5,4,0)undec-7-ene. 24. A composition according to any one of the preceding claims, wherein the total amount of catalyst used is from 0.1% to 2% by weight of the composition. 25. The composition of any one of the preceding claims, further comprising a secondary flame retardant additive. 26. The composition of claim 25, wherein the auxiliary flame retardant additive is ammonium polyphosphonate, red phosphorus, phosphite, 9,10-dihydro-9-oxa-phosphaphenanthrene-10-oxide (HCA) , Phosphazines, nitrogen-containing flame retardants, halogenated flame retardants, halogenated epoxy resins, phosphorus-halogenated flame retardants, organic acid salts, inorganic metal hydrates, boron or antimony-containing compounds. 27. A method of preparing an epoxy resin composition, the epoxy resin composition comprising: epoxy resin, Phosphonates,  Nitrogen-containing crosslinkers with an amine functionality of at least 2, Catalyst, which can not only accelerate the chemical reaction speed of phosphonate ester and epoxy resin, but also can increase the curing speed of epoxy resin and crosslinking agent, and optional Lewis acid, the amount of which does not exceed 2 moles per mole of catalyst Lewis acid, The method comprises: preparing a first composition comprising an epoxy resin, and a second composition comprising a curing catalyst, wherein either the first or the second composition also comprises a phosphonate and a nitrogen-containing cross-linked compound having an amine functionality of at least 2 joint agent; The first composition and the second composition are mixed, and then the compositions are cured to produce a cured flame retardant epoxy resin. 28. The method of claim 27, wherein the phosphonate, nitrogen-containing crosslinker and catalyst are all present in the second composition. 29. The method of claim 27, wherein the phosphonate, nitrogen-containing crosslinker is present in the first composition and the catalyst is present in the second composition.