WO2015179232A1 - Halogen-free active ester curing agent compound for epoxy resins, flame retardant composition comprising same, articles made therefrom and method of making said compound - Google Patents

Abstract

There is provided herein a curing agent compound for curing thermosetting resins, e.g., epoxy resins, a composition comprising a thermoplastic and/or thermosetting resin, e.g., an epoxy resin and the curing agent, an article comprising the curing agent, and a method of making the curing agent.

Description

HALOGEN-FREE ACTIVE ESTER CURING AGENT COMPOUND FOR EPOXY RESINS, FLAME RETARDANT COMPOSITION COMPRISING SAME, ARTICLES MADE THEREFROM AND METHOD OF MAKING SAID COMPOUND

This Application claims priority to U.S. Provisional Application No. 62/001 ,239 filed on May 21, 2014 and incorporates the same herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to the field of flame retardants, specifically phosphorous- containing flame retardants for electronic applications such as printed wiring boards.

BACKGROUND OF THE INVENTION

Synthetic resins are widely used in both industrial and consumer electronics because of among other things, their chemical resistance, mechanical strength and electrical properties. For example, synthetic resins can be used in electronics as protective films, adhesive materials and/or insulating materials, such as interlayer insulating films. To be useful for these applications, the synthetic resins need to provide ease of handling and certain necessary physical, thermal, electrical insulation and moisture resistance properties. For example, synthetic resins having a low dielectric constant, and a low moisture uptake as well as a high glass transition temperature (Tg) can be a desirable combination of properties for electronic applications.

Synthetic resins, however, can be flammable. As such, different approaches have been made to impart a desired level of flame resistance to synthetic resins, e.g., epoxy resin, where such approaches entail employing either halogen-free flame retardant compounds or halogen- containing flame retardant compounds. Halogenated compounds, however, are now undergoing additional scrutiny, and the various non-halogenated compounds available do not provide the desired level of flame retardancy to the synthetic resin. It would be desirable to provide a desired level of flame retardancy to a synthetic resin such as an epoxy resin while still maintaining a suitable combinations of properties for electronic applications. SUMMARY OF THE INVENTION

It is therefore a feature of the present invention to provide a compound(s), which can function as a halogen-free active ester curing agent for thermosetting resins, e.g., epoxy resins, which cured epoxy resins can be employed in electronic applicatons while maintaining a low dielectric constant, and a low moisture uptake as well as a high glass transition temperature (Tg).

It will be understood herein that in one non-limiting embodiment the expression

"halogen- free active ester curing agent for epoxy resins" can be used interchangeably with "halogen-free curing agent for epoxy resins", "epoxy curing agent", "curing agent for epoxy", "epoxy resin curing agent" and "curing agent", and the like.

There is provided herein in one embodiment herein a compound having the general formula (I):

wherein the dashed line represents a bond to the structure of formula (I) above; R is hydrogen, -OC(=0)R*, or -OH wherein R* is an alkyl group containing from 1 to about 8 carbon atoms, more specifically from 1 to about 6 carbon atoms, and most specifically from 1 to about 4 carbon atoms or substituted or unsubstituted phenyl, wherein the substituted phenyl can in one embodiment be substituted with a linear or branched alkyl of up to about 6 carbon atoms; R¹ is an alkyl group of from 1 to 6 carbon atoms, more specifically from 1 to about 4 carbon atoms, or R; and, R⁴ and R^J are each independently selected from -CH₂-DOPO wherein DOPO is as defined, R¹, -OH, or a moiety of the general formula (III):

wherein R⁴ is selected from a bond, a divalent alkylene moiety containing from 1 to about 6 carbon atoms, more specifically from 1 to about 4 carbon atoms, more specifically isopropylene, and a sulphone; R⁵ is selected from hydrogen, -OH and -OC(=0)R*, wherein R* is as defined; and, the dash from R⁴ represents the bond to the structure of general formula (I);

provided that when R² is of the general formula (III) and any one or more of R, R^l, and R³ are -OH, then R⁵ is not -OH, and provided that when R³ is of the general formula (III) and any one or more of R, R^l, and R³ are -OH, then R⁵ is not -OH; and,

provided that at least one of R, R¹, R², R³ or R⁵ is -OC(=0)R*, and more specifically wherein at least two of R, R¹, R², R³ or R⁵ is -OC(=0)R*, and most specifically wherein at least three of R, R¹, R², R³ or R⁵ is -OC(=0)R*, and provided that only one of R² or R³ is a moiety of the general formula (III), such that when R² is a moiety of the general formula (III), R³ is selected from -CH₂-DOPO or R , and when R is a moeity of the general formula (III), R is selected from -CH₂-DOPO or R¹.

It will be understood herein that the compound of the formula (I) as described herein can function as a curing agent for curing thermosetting resins, e.g., epoxy resin, as described herein or in another embodiment as a flame retardant additive for thermoplastic resin compositions and/or formulations. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is the Pressure Cooker Test (PCT) results of an epoxy laminate containing Composition A from the conditions of 30 minutes and 288°C solder bath as described in

Example 4.

Figure 2 is a graph of a DSC at 10°C/minute for Composition B described in Example 5

Figure 3 is a graph of the dynamic viscosity profile of a B-stage prepreg at a ramp rate of 5°C/minute in a rheometer of Composition B as described in Example 5.

Figure 4 is a graph of the overlays of storage modulus, loss modulus and complex viscosity of a B-staged resin system in a rheometer of Composition B described in Example 5.

Figure 5 is a graph of a Dynamic Mechanical Analysis measurement for the glass transition temperature for the laminate of Composition B as described in Example 5.

Figure 6 is a graph of a Thermogravimetric Analysis for the laminate of Composition B as described in Example 5.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compound(s), which can function as a halogen-free active ester curing agent(s) for thermoseting resins, e.g., epoxy resins, which cured epoxy resins can be employed in electronic applicatons while maintaining a low dielectric constant, and a low moisture uptake as well as a high glass transition temperature (Tg). Advantageously herein, the compound(s) which function as a halogen-free active ester curing agent for thermosetting resins, e.g., epoxy resins, when reacted with epoxy resins, the products are in the absence of hydroxyl groups, such as secondary hydroxyl groups thus, avoiding the high water absorption and higher dielectric constant of conventional curing systems, which when reacted with epoxy the products therein contain such secondary hydroxyl groups. In addition, the halogen-free active ester curing agent(s) described herein can be used as a flame retardant additive in thermoplastic compositions and/or formulations while maintainig optimal properties of the thermoplastic material.

Some more specific embodiments of compound(s) which can be used as the curing agent compound for curing thermosetting resins, e.g., epoxy resin, is wherein the compound is selected from any one or more of the formulae (IV)-(VIII):

wherein DOPO and R* are as defined herein and R⁶ is an alkyl of from 1 to about 6 carbon atoms;

wherein DOPO and R* are as defined herein and R⁶ is an alkyl of from 1 to about 6 carbon atoms, more specifically from 1 to about 4 carbon atoms, and most specifically from 1 to about 3 carbon atoms;

wherein DOPO and R* are as defined herein;

wherein DOPO and R* are as defined herein; and,

(VIII) wherein DOPO and * are as defined herein, and X is selected from -(CH₂ wherein n is from 1 to 6, more specifically from 1 to 4, and even more specifically from 1 to 3, sulphone and a bond. In one separate non-limiting embodiment herein formulae (VI)-(VIII) can be such wherein one or both of the -CH2-DOPO moieties on the right hand side of the structure are not present.

In one non-limiting embodiment, the compound which can be used as the curing agent compound for curing thermosetting resins, e.g., epoxy resin, is of the general formula (IX):

wherein R* and DOPO are as defined herein.

In one embodiment, the compound(s) which can be used as the curing agent compound for curing thermosetting resins, e.g., epoxy resin (e.g., the halogen-free active ester curing agent for epoxy resins described herein) can be a phosphorus containing compound such as those having at least one active ester group(s) per molecule, or one phenolic group and one active ester group(s) per molecule and a phosphorus content of at least 4 wt-percent. And more preferably the phosphorus containing compounds are those having at least two active ester groups per molecule and phosphorus content of 6%. The compounds (I) and/or (IV)-(IX) described herein meet these requirements and are preferably substantially free (or completely free) of bromine atoms, and more preferably substantially free (or completely free) of halogen atoms. Compounds (I) and/or (IV)-(IX) described herein may also be used as a non-reactive additive, such as when used with a thermoplastic or other thermosetting systems, e.g., other than epoxy. For example, Compound (I) and/or (IV)- (IX) noted above can be used a charring agent to provide an insulating layer of char at elevated temperatures for thermoplastic formulations and for thermosetting formulations.

The terms active ester refers to an aromatic ester that can react with epoxy according to the following scheme:

wherein R as defined here for the above scheme can be a linear or branched alkyl of from 1 to 6 carbon atoms or a non-substituted phenyl or a substituted phenyl containing up to about 12 carbon atoms, wherein the substituted phenyl can be substituted with a linear or branched alkyl of from 1 to 6 carbon atoms.

In contrast to a conventional epoxy curing scheme :

In one embodiment herein there are provided compounds, compositions and/or formulations obtainable by reacting, blending or mixing Compound (I), and/or the related compounds (IV)-(IX) with other components such as a thermosetting resin or a thermoplastic material or a mixture of a thermosetting resin and a thermoplastic material to form various ignition resistant compounds, compositions or formulations useful in various applications such as prepregs, laminates, coatings, molding articles and composite products.

Another embodiment herein is directed to phosphorous-containing epoxy resin curable formulations comprising (i) Compound (I), and/or the related compounds (IV)-(IX) (ii) an epoxy resin or a mixture of epoxy resins, (iii) optionally, a co-crosslinker, (iv) optionally, a curing catalyst, and (v) optionally, a Lewis acid.

Yet in another embodiment herein there is provided a curable flame-resistant epoxy resin composition comprising (i) the above phosphorus-containing compound (e.g., Compound (I), and/or (IV)-(IX)), (ii) optionally, a benzoxazine-containing compound, (iii) a crosslinkable epoxy resin or a blend of two or more epoxy resins having more than one epoxy group per molecule, (iv) optionally a co-crosslinker and, (v) optionally, a curing catalyst to obtain a curable flame resistant epoxy resin composition. Such curable flame resistant epoxy resin compositions may be used to make prepregs, which prepregs may be used to make laminates and circuit boards useful in the electronics industry. The epoxy resin composition may also be used to coat metallic foils such as copper foils to make resin coated copper foils for so called build-up technology.

The phosphorus-containing compounds, (Compounds (I), and/or (IV)-(IX) described herein), and derivatives thereof, may also be combined with at least one thermoplastic resin to make an ignition-resistant thermoplastic composition.

The phosphorus-containing compounds, (Compounds (I), and/or (IV)-(IX) described herein) and derivatives thereof, may also be combined with at least one thermoplastic resin and thermosetting systems (epoxy and curing agents) to make a hybrid ignition-resistant

thermoplastic containing thermosetting composition.

Ignition Resistant Epoxy Resin Composition (Epoxy resin composition)

In one embodiment of the present invention, the phosphorus-containing compound (I) , and/or (IV)-(IX) described herein as well in one embodiment, combinations thereof, may be used, as one component, of a curable (crosslinkable) phosphorus- containing flame resistant epoxy resin composition. In this embodiment, the curable phosphorus-containing flame-resistant epoxy resin composition comprises (i) the phosphorus-containing compound, Compound (I), and/or (IV)-(IX) described herein, (ii) at least one epoxy resin such as those selected from halogen-free epoxies, phosphorus-free epoxies, and phosphorus-containing epoxies and mixtures thereof, including, but not limited to DEN 438, DER 330 Epon 164 (DEN and DER are trademarks of The Dow Chemical Company), epoxy functional polyoxazolidone containing compounds, cycloaliphatic epoxies, GMA/styrene copolymers, and the reaction product of DEN 438 and DOPO resins; and optionally (iii) at least one co-crosslinker, and optionally one or more of a curing catalyst, a Lewis acid, an inhibitor, and a benzoxazine-containing compound. The curable phosphorous containing flame resistant epoxy resin composition optionally may contain at least one additional crosslinkable epoxy resin or a blend of two or more epoxy resins other than and different from component (ii) above. The curable phosphorous-containing flame resistant epoxy resin composition may also optionally contain at least one curing catalyst and at least one inhibitor. All of the above components may be blended or mixed together in any order to form the curable phosphorus-containing flame-resistant epoxy resin composition.

The curable phosphorous-containing flame resistant epoxy resin compositions prepared according to the present invention, whether made either by reacting a mixture of Compound (I), and/or Compounds (IV)-(IX) described herein, an epoxy resin, and optionally another co- crosslinker (i.e. another curing agent); may be used to make prepregs, which, in turn, may be used to make laminates and circuit boards useful in the electronics industry. The phosphorous- containing flame resistant epoxy resin compositions may also be used to coat metallic foils such as copper foils to make resin coated copper foils for so called build-up technology.

The epoxy resins which can be used in the herein described invention include, in one embodiment, polyepoxides having the following general Formula (X):

wherein "R " is substituted or unsubstituted aromatic, aliphatic, cycloaliphatic or heterocyclic group having a valence of "q", where "q" preferably has an average value of from 1 to less than about 8. Examples of the polyepoxide compounds useful in the present invention include the diglycidyl ethers of the following compounds: resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (l,l-bis(4-hydroxylphenyl)-l -phenyl ethane), bisphenol F, bisphenol K, phenol-formaldehyde novolac resins, alkyi substituted phenol-formaldehyde resins, phenol- hydroxybenzaldehyde resins, cresol-hydroxybenzaldehyde resins, dicyclopentadiene-phenol resins, dicyclopentadiene-substituted phenol resins tetramethylbiphenol, and any combinations thereof.

Examples of particular polyepoxide compounds useful in the present invention include a diglycidyl ether of bisphenol A having an epoxy equivalent weight (EEW) between 177 and 189 sold by The Dow Chemical Company under the trademark D.E.R. 330; the halogen-free epoxy- terminated polyoxazolidone resins, phosphorus element containing compounds; cycloaliphatic epoxies; and copolymers of glycidyl methacrylate ethers and styrene.

Preferred polyepoxide compounds include epoxy novolacs, such as D.E.N. 438 or D.E.N. 439 (trademarks of The Dow Chemical Company); cresole epoxy novolacs such as QUATREX 3310, 3410 and 3710 available from Ciba Geigy; trisepoxy compounds, such as TACTIX 742 (trademark of Ciba Geigy Corporation of Basel, Switzerland); epoxidized bisphenol A novolacs, dicyclopentadiene phenol epoxy novolacs; glycidyl ethers of

tetraphenolethane; diglycidyl ethers of bisphenol- A; diglycidyl ethers of bisphenol-F; and diglycidyl ethers of hydroquinone.

In one embodiment, the most preferred epoxy compounds are epoxy novolac resins (sometimes referred to as epoxidized novolac resins, a term which is intended to embrace both epoxy phenol novolac resins and epoxy cresol novolac resins). Epoxy novolac resins (including epoxy cresol novolac resins) are readily commercially available, for example under the trade names D.E.N, (trademark of The Do Chemical Company), and QUATREX and TACTiX 742 (trademarks of Ciba Geigy).

Preferred compounds of the type mentioned above have epoxy equivalent between 150- 400 and most preferably from 160-300 and molecular weight above 500 and most preferable between 700-2500. The polyepoxide useful in the present invention is preferably substantially free (or completely free) of bromine atoms, and more preferably substantially free (or completely free) of halogen atoms.

One non-limiting example of polyepoxides that are useful in the present invention and that are substantially free of halogen atoms are the phosphorus-containing epoxy resins such as those which are the reaction products of an epoxy compound containing at least two epoxy groups and a reactive phosphorus-containing compound such as 3,4,5,6-dibenzo-l,2- oxaphosphane-2-oxide (DOP), or 10-(2',5'-dihydroxyphenyl)-9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-o- xide (DOP-HQ).

The amount of epoxy in the compositions described herein, e.g., the curable

phosphorous-containing flame resistant epoxy resin compositions, the thermoset composition and the hybrid composition is such that the final formulation of epoxy, any optional phosphorous containing epoxy, compound of the general formula (I) and/or (IV)-(IX) in the amounts described herein, and any other components in the amounts described herein or known to those skilled in the art, is such that the total phosphorous content of the composition is from 1 weight percent to about 5 weight percent, more specifically from about 2 to about 3.5 weight percent. Thus, one skilled in the art will formulate the amount of epoxy to be commensurate with such other components so as to have a final phosphorous content as described above.

The amount of such phosphorus containing epoxy in the final composition can vary from 0-90 parts, preferably 20-80 parts and most preferably from 30-50 parts based on 100 parts of epoxy resin.

The amounts of epoxy resin described herein can in one non-limiting embodiment be the amounts of the thermoplastic resin in the thermoplastic composition described herein, the thermoset resin in the thermoset composition described herein and the combined amount of resins in the hybrid composition described herein.

The flame retardant effective amount of the compound (I) and/or (IV)- (IX) which can be used as the compound for curing epoxy resin herein in the curable epoxy resin composition described herein will vary depending on the specific epoxy resin and the specific compound being employed as well as specific parameters of processing as are known by those skilled in the art. In one non-limiting embodiment, flame retardant effective amount of the compound (I) and/or compound (IV)-(IX) which can be used for curing epoxy resin is from about 10 to about 150 parts by weight per 100 parts of the epoxy resin, more specifically from about 30 to about 100 parts by weight per 100 parts of the epoxy resin and most specifically from about 50 to about 70 parts by weight per 100 parts of the epoxy resin. To provide adequate flame retardancy the compositions herein will have from 1.0% P to about 5% P in the final composition. In one embodiment, the above stated amounts of compound (I) and/or (IV)-(IX) can be the amounts of compound (I) and/or (IV)- (IX) used in any of the epoxy resin composition, the thermoplastic composition, the thermoset composition and the hybrid composition described herein.

As described above, a phosphorous-containing flame resistant epoxy resin compositions may be formed by blending (i) the phosphorus-containing product, Compound (I) and/or

Compounds (IV)-(iX) described herein, (ii) at least one crosslinkable epoxy compound, and optionally (iii) at least one co-crosslinker, as well as any of the other optional components described herein; or in another embodiment, the phosphorous-containing flame resistant epoxy resin compositions may be formed by blending (i) an epoxidized Compound (I) and/or

Compounds (IV)-(IX), at least one crosslinkable phosphorous-containing epoxy compound, and (iii) at least one co-crosslinker, as well as any of the other optional components described herein. The phosphorous-containing flame resistant epoxy resin compositions may, optionally, contain at least one crosslinkable epoxy resin other than the crosslinkable phosphorus-containing epoxy compounds in (ii) above. In one embodiment herein it will be understood that the term

"crosslinkable" in crosslinkable phosphorus-containing epoxy compound is understood to be a phosphorous-containing epoxy compound which has more than 2 epoxy functionalities, as would be understood by those skilled in the art.

With any of the compositions above where an epoxy resin is present, any number of co- crosslinking agents (i.e., in addition to the phosphorous compound (I) and/or (IV)-(IX)) may optionally also be used. Suitable co-crosslinkers that may optionally be present in combination with the phosphorus-containing epoxy compounds according to the present invention include, for example, are the multifunctional co-crosslinkers as are known to those in the art. The-co-crosslinkers include, for example, copolymers of styrene and maleic anhydride having a molecular weight (M_w) in the range of from 1,500 to 50,000 and an anhydride content of more than 15 percent. Commercial examples of these materials include SMA 1000, SMA 2000, and SMA 3000 and SMA 4000 having styrene-maleic anhydride ratios of 1:1, 2:1, 3:1 and 4:1, respectively, and having molecular weights ranging from 6,000 to 15,000, which are available from Elf Atochem S.A.

Other preferred co-crosslinkers useful in the present invention include hydroxyl- containing compounds such as those represented by the following Formula (XI):

wherein "R " is hydrogen or an alkyl group having from 1 to 20, preferably from 1 to 10, and more preferably 1 to 5 carbon atoms and "t" is an integer of from 0 to 20, preferably from 1 to 10, and more preferably from 2 to 5.

Commercially available products having the above Formula (XI) include, for example, PERSTORP 85.36.28, which is a phenolic resin obtained from phenol and formaldehyde having an average Mettler softening point of 103°C, melt viscosity at 150°C=1.2 Pas and a functionality of 6 to 7. Another example includes SD1708 (from Momentive): Viscosity at 150°C, 2200-3800 cps Softening Pt: 110°C; HRJ 13399 ( from SI Group): Specific Gravity 1.20, Softening Pt: 90- 105; HRJ12952 ( from SI Group): Specific Gravity 1.25, Softening Pt: 97-107; FRJ425 (from SI Group): Specific Gravity 1.24, Softening Pt: 112-118; BRJ 473 liquid (from SI Group): Specific Gravity 1.10, Brookfield viscosity: 1000-4500 cps. One example of co-crosslinker that is suitable in the compositions described herein are active ester phenolic resins with general formula (XII):

where R is hydrogen, a aliphatic moiety of from 1 to 10 carbon atoms, or phenyl or a substituted phenyl; R¹⁰ is an aliphatic moiety of from 1 to 4 carbon atoms, or a phenyl or a substituted phenyl group. One examples of a commercial curing system of this type is EPICLON HPC- 8000-65T available from DIC corporation, Japan.

Other phenolic functional materials which are suitable as co-crosslinker include compounds which form a phenolic crosslinking agent having a functionality of at least 2 upon heating. Some examples of these compounds are benzoxazine groups-containing compounds. Examples of compounds which form a phenolic crosslinking agent upon heating include phenolic species obtained from heating benzoxazine, for example as illustrated in the following chemical equation:

wherein "u" is greater than 1 and preferably up to about 100,000; and wherein "R¹¹" and "R¹²" may be, independently and separately, the same or different of a hydrogen, an allyl group from 1 to about 10 carbon atoms, such as methyl, a 6 to 20 carbon atom aromatic group such as phenyl or a 4 to 20 carbon atom cycloaliphatic group such as cyclohexane.

Examples of the above compounds also include benzoxazine of phenolphthalein.

benzoxazine of bisphenol- A, benzoxazine of bisphenol-F, benzoxazine of phenol novolac, and mixtures thereof. A mixture of these compounds and Formula (XI) may also be used in the present invention. Non-limiting examples of commercial benzoxazines from Huntsman include examples such as Bisphenol A benzoxazine (MT35600) ; Bisphenol F benzoxazine (MT35700) Phenolphthalein benzoxazine (MT35800); Thiodiphenol benzoxazine (MT35900) and,

Dicyclopentadiene benzoxazine (MT36000)

When a co-crosslinker is used in the present invention, the co-crosslinker is present in an amount to crosslink of less than 50 percent of the stoichiometric amount needed to cure the thermosetting resin, e.g., the epoxy resin, is more preferably less than about 40 % amount needed to cure the thermosetting resin, e.g., epoxy resin and most preferably less than about 35 % amount needed to cure the thermosetting resin, e.g., epoxy resin. Any of the curable compositions of the present invention described herein may comprise a curing catalyst. Examples of suitable curing catalyst (catalyst) materials useful in the present invention include compounds containing amine, phosphine, ammonium, phosphonium, arsonium or sulfonium moieties or mixtures thereof. Particularly preferred catalysts are heterocyclic nitrogen-containing compounds.

The catalysts (as distinguished from co-crosslinkers) 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. For instance, 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.

Among preferred 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.

Examples of these amines include, among others, l,8-diazabicyclo(5.4.0)undec-7-en (DBU), 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 Weak 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.

Examples of suitable heterocyclic nitrogen- containing catalysts include 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. Especially preferred are the alkyl-substituted imidazoles; 2,5-chloro-4-ethyl imidazole; and phenyl-substituted imidazoles, and mixtures thereof. Even more preferred are N-methylimidazole; 2-methylimidazole; 2-ethyl-4-methylimidazole; 1,2- dimethylimidazole; and 2-methylimidazole and mixtures thereof. Especially preferred is 2- phenylimidazole.

The amount of curing catalyst used depends on the molecular weight of the catalyst, the activity of the catalyst and the speed at which the polymerization is intended to proceed. In general, the curing catalyst is used in an amount of from 0.01 parts per 100 parts of resin (p.h.r.) to about 1.0 p.h.r., more specifically, from about 0.01 p.h.r. to about 0.5 p.h.r. and, most specifically, from about 0.1 p.h.r. to about 0.5 p.h.r. In one embodiment herein it will be understood herein that parts of resin relates to the parts of curable epoxy resin described herein, i.e., the total amount of the curable composition excluding catalyst, (total grams of epoxy + Compound (I) and any other components present other than the curing catalyst = 100% and then taking 100 grams of this is equal to 100 parts of resin); catalyst is added in above ranges to 100 parts of this total weight amount

Preferably, a Lewis acid is also employed in any of the curable epoxy resin compositions of the present invention described herein, especially when the catalyst is particularly a heterocyclic nitrogen-containing compound.

The Lewis acids useful in the present invention include for example one or a mixture of two or more haiides, oxides, hydroxides and alkoxides of zinc, tin, titanium, cobalt, manganese, iron, silicon, aluminum, 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 haiides, zinc haiides (such as zinc chloride) and other Lewis acids that tend to have a relatively weak conjugate base. Preferably 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. These Lewis acids are very effective in curing epoxy resins when combined with the heterocyclic nitrogen-containing compounds, referred to above.

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 mole of Lewis acid per mole of heterocyclic nitrogen compound, more preferably at least 0.3 mole of Lewis acid per mole of heterocyclic nitrogen-containing compound.

The curable compositions of the present invention may optionally have boric acid and/or maleic acid present as a cure inhibitor. In that case, the curing agent is preferably a polyamine or polyamide. The amount of cure inhibitor will be known by those skilled in the art.

The curable compositions of the present invention may also optionally contain one or more additional flame retardant additives including, for example, red phosphorus, encapsulated red phosphorus or liquid or solid phosphorus-containing compounds, for example, "EXOLIT OP 930", EXOLIT OP 910 from Clariant GmbH and ammonium polyphosphate such as "EXOLIT 700" from Clariant GmbH, a phosphite, or phosphazenes; nitrogen-containing fire retardants and/or synergists, for example melamines, melem, cyanuric acid, isocyanuric acid and derivatives of those nitrogen-containing compounds; halogenated flame retardants and halogenated epoxy resins (especially brominated epoxy resins); synergistic phosphorus-halogen containing chemicals or compounds containing salts of organic acids; inorganic metal hydrates such as Sb₂0 , SbaOj, aluminum trihydroxide and magnesium hydroxide such as "ZEROGEN 30" from Martinswerke GmbH of Germany, and more preferably, an aluminum trihydroxide such as "MARTINAL TS-610" from Martinswerke GmbH of Germany; boron-containing compounds; antimony-containing compounds; silica and combinations thereof.

When additional flame retardants which contain phosphorus are present in the

composition of the present invention, the phosphorus-containing flame retardants are preferably present in amounts such that the total phosphorus content of the epoxy resin composition is from 0.2 wt. percent to 5 wt. percent.

The curable compositions of the present invention may also optionally contain other additives of a generally conventional type including for example, stabilizers, other organic or inorganic additives, pigments, wetting agents, flow modifiers, UV light blockers, and fluorescent additives. These additives can be present in amounts of from 0 to 5 weight-percent and is preferably present in amounts less than 3 weight percent.

The flame resistant epoxy resin is preferably free of bromine atoms, and more preferably free of halogen atoms.

The compositions described above are useful for making coating formulations, encapsulation, composites, and adhesives, molding, bonding sheets, and laminated plates. The compositions of the present invention can be used to make composite materials by techniques well-known in the industry, such as by pultrusion, molding, encapsulation, or coating. As an illustration, a coating formulation may comprise (i) Compound (I), and/or Compounds (IV)-(IX) (ii) a solid epoxy resin, and (iii) a hardener such as an amine or phenolic hardener. The amounts of hardener will be known by those skilled in the art.

The present invention is particularly useful for making B-staged prepregs, laminates, bonding sheets, and resin coated copper foils by well known techniques in the industry.

Ignition-Resistant Thermoplastic Resins (Thermoplastic resin composition)

In another embodiment of the present invention, the phosphorus-containing product, Compound (I), and/or Compounds (IV)-(IX) are used to make phosphorus-containing ignition resistant thermoplastic resins.

A halogen-free ignition-resistant thermoplastic resin composition are obtainable by blending (i) the phosphorus-containing compound, Compound (I), and/or Compounds (IV)-(IX) according to the present invention with (ii) at least one thermoplastic resin, and optionally any one or more of the optional components described for the thermosetting (e.g., epoxy) resin composition described herein.

Typical thermoplastic polymers include, but are not limited to, polymers produced from vinyl aromatic monomers and hydrogenated versions thereof, including both diene and aromatic hydrogenated versions, including aromatic hydrogenation, such as styrene-butadiene block copolymers, polystyrene (including high impact polystyrene), acrylonitrile-butadiene-styrene (ABS) copolymers, and styrene-acrylonitrile copolymers (SAN); polycarbonate (PC), ABS/PC compositions, polyethylene terephthalate, epoxy resins, hydroxy phenoxy ether polymers (PHE), ethylene vinyl alcohol copolymers, ethylene acrylic acid copolymers, polyolefin carbon monoxide interpolymers, chlorinated polyethylene, polyolefins (for example, ethylene polymers and propylene polymers, such as polyethylene, polypropylene, and copolymers of ethylene and/or propylene with each other or with an alpha-olefin having at least 4, more preferably at least 6, and preferably up to 12, and more preferably up to 8, carbon atoms), cyclic olefin copolymers (COC's), other olefin copolymers (especially copolymers of ethylene with another olefin monomer, such as from 1 to 12 carbon atom alken-l-yl groups) and homopolymers (for example, those made using conventional heterogeneous catalysts), polyphenylene ether polymers (PPO) and any combination or blend thereof.

Thermoplastic polymers are well-known by those skilled in the art, as well as methods for making them. In one embodiment, the thermoplastic polymer is a rubber-modified

monovinylidene aromatic polymer produced by polymerizing a vinyl aromatic monomer in the presence of a dissolved elastomer or rubber.

The thermoplastic polymer or polymer blend is employed in the halogen-free ignition resistant polymer compositions of the present invention in amounts of at least 35 parts by weight, preferably at least 40 parts by weight, more preferably at least 45 parts by weight, and most preferably at least 50 parts by weight based on 100 parts by weight of the halogen-free ignition resistant polymer composition of the present invention. In general, the thermoplastic polymer component is employed in amounts less than or equal to 99 parts by weight, preferably less than or equal to 95 parts by weight, more preferably less than or equal to about 90 parts by weight, and most preferably less than or equal to about 85 parts by weight based on 100 parts by weight of the halogen-free ignition resistant polymer composition of the present invention.

In one embodiment, the halogen-free ignition resistant polymer composition of the present invention comprises Compound (I) and/or Compounds (IV) -(IX) with a blend of two thermoplastic polymers wherein at least one of the thermoplastic polymers is for example a polyphenylene ether. Polyphenylene ethers are made by a variety of well known catalytic and non-catalytic processes from corresponding phenols or reactive derivatives thereof.

When used in combination with another thermoplastic polymer, the polyphenylene ether resin is preferably employed in the halogen-free ignition resistant polymer compositions of the present invention in amounts of at least 5 parts by weight, preferably 10 part by weight, more preferably at least 12 parts by weight, more preferably at least 15 parts by weight, and most preferably at least 18 parts by weight to 30 parts by weight, preferably to 28 parts by weight, more preferably to 25 parts by weight, based on 100 parts by weight of the halogen-free ignition resistant polymer composition of the present invention. The thermoplastic and polyphenylene ether polymer can be prepared as a blend prior to incorporation into the composition of the present invention, or each polymer can be incorporated individually.

The compositions of the present invention may include other additives such as modifiers that include compounds containing functionalities which will enhance the mechanical properties of the composition and are compatible with the thermoplastic resin. For thermoplastic resins such as monovinylidene aromatic s and conjugated dienes, such functionalities might include, but are not limited to, butadienes, styrene-maleic anhydrides, polybutadiene-maleic anhydride copolymers, carboxylic acid terminated butadienes, and carboxylic acid functionalized polystyrenes. Any combination of modifiers can be used in modifying the phosphorus element- containing epoxy compounds.

The amount of Compound (I), and/or Compounds (IV)-(IX) used in the ignition resistant thermoplastic polymer composition of the present invention is typically at least 1 weight-percent, generally at least 5 weight-percent, preferably at least 10, more preferably at least 15, and most preferably at least 20, weight-percent and less than 50, preferably less than 45, more preferably less than 40 and most preferably less than 35, weight-percent, based on the total weight of the ignition resistant polymer composition.

The thermoplastic resin compositions herein can contain any of the components and or ranges of amounts of components described herein for the thermosetting composition, the epoxy resin composition, or the hybrid compositions and vice-versa and of the thermoplastic composition, i.e., any of the components and or amounts of the components of the thermoplastic composition described herein can be used in any of the thermosetting composition, the epoxy resin composition, or the hybrid compositions described herein.

Preparation of the ignition resistant thermoplastic polymer composition of the present invention can be accomplished by any suitable mixing means known in the art, including dry blending the individual components and subsequently melt mixing, either directly in the extruder used to make the finished article or pre-mixing in a separate extruder. Dry blends of the compositions can also be directly injection molded without pre-melt mixing.

When softened or melted by the application of heat, the ignition resistant thermoplastic polymer composition of this invention can be formed or molded using conventional techniques such as compression molding, injection molding, gas assisted injection molding, calendaring, vacuum forming, thermoforming, extrusion and/or blow molding, alone or in combination. The ignition resistant thermoplastic polymer composition can also be formed, spun, or drawn into films, fibers, multi-layer laminates or extruded sheets, or can be compounded with one or more organic or inorganic substances, on any machine suitable for such purpose.

In one embodiment, the thermoplastic compositions of the present invention can be utilized in the preparation of foam. The ignition resistant thermoplastic polymer composition is extruded into foam by melt processing it with a blowing agent to form a foamable mixture, extruding said foamable mixture through an extrusion die to a region of reduced pressure and allowing the foamable mixture to expand and cool. Conventional foam extrusion equipment, such as screw extruders, twin screw extruders and accumulating extrusion apparatus can be used. In another embodiment of the present invention, the halogen-free ignition resistant thermoplastic polymer composition of the present invention may optionally include, in addition to Compound (I), and/or Compounds (IV)-(IX) other phosphorus- containing compounds.

Optionally, the thermoplastic composition of the present invention may also include other flame retardant additives which can be phosphorus or non-phosphorus materials as described above.

The amount of optional phosphorus-containing compounds, other than Compound (I), and/or Compounds (IV) -(IX) and/or the optional flame retardant additives used in the composition of the present invention may be from 0 up to 30 weight percent. The amount of optional phosphorus-containing component, other than Compound (I), and/or Compounds (IV)- (IX) when present, is preferably at least 1 weight-percent and preferably up to 30 weight-percent based on the total weight of the thermoplastic resin.

The amount of component, Compound (I), and/or Compounds (IV)-(IX) is preferably at least 5 weight-percent and preferably up to 20 weight-percent, based on the total weight of the thermoplastic resin.

The ignition resistant thermoplastic resin is preferably substantially free of bromine atoms, and more preferably completely free of halogen atoms.

The halogen- free ignition resistant thermoplastic polymer compositions of the present invention are useful to fabricate numerous useful articles and parts. Some of the articles which are particularly well suited include television cabinets, computer monitors, related printer housings which typically requires to have excellent flammability ratings. Other applications include automotive and small appliances.

Ignition-Resistant Thermosetting Composition (Thermosetting composition)

In another embodiment of the present invention, the phosphorus-containing product, Compound (I), and/or Compounds (IV)-(IX) is used to make a phosphorus-containing ignition resistant thermosetting composition, e.g., in one non-limiting embodiment wherein the thermoset polymer is in addition to or other than epoxy. A halogen-free ignition-resistant thermosetting composition is obtainable by blending (i) the phosphorus-containing compound, Compound (I), and/or Compounds (IV)-(IX) according to the present invention with (ii) at least one thermosetting system. Examples of thermosetting systems are epoxy, polyurethane, polyisocyanates, benzoxazine ring- containing compounds, unsaturated resin systems containing double or triple bonds, polycyanate ester, bismaleimide, triazine, bismaleimide and mixtures thereof.

The thermoset resin compositions herein can contain any of the components and or ranges of amounts of such components described herein for the curable epoxy resin composition, the thermoplastic composition or the hybrid compositions and vice- versa and of the thermoset resin composition, i.e., any of the components and or amounts of the components of the thermoset composition described herein can be used in any of the epoxy composition, the thermoplastic resin composition, or the hybrid compositions described herein.

Ignition-Resistant Thermoplastic/Thermosetting Hybrid Systems (Hybrid composition)

In another embodiment of the present invention, the phosphorus-containing product, Compound (I), and/or Compounds (IV)-(IX) is used to make phosphorus-containing ignition resistant hybrid resin system that contains both a thermoplastic and a thermosetting system.

The hybrid ignition-resistant thermoplastic and thermosetting compositions are obtainable by blending (i) the phosphorus-containing compound, Compound (I), and/or

Compounds (IV)-(IX) according to the present invention with (ii) a thermoplastic resin and (iii) a thermosetting system. Examples of thermoplastic resins are polyphenylene oxide (PPO), mixtures thereof, and others as described above. Examples of thermosetting systems are epoxy, polyurethane, polyisocyanates, benzoxazine ring-containing compounds, unsaturated resin systems containing double or triple bonds, polycyanate ester, bismaleimide, triazine,

bismaleimide and mixtures thereof. The hybrid ignition-resistant thermoplastic and thermosetting composition can contain any of the optional components and amounts thereof described in the subject disclosure. The amount of thermoplastic resin in the hybrid composition can be from about 20 to about 95 and preferably from about 30 to about 80, while the amount of thermoset resin can be from about 10 to about 20 and more preferably from about 30 to about 40 wherein said amounts are based on the total amount of thermoplastic and thermoset resin employed.

The hybrid resin compositions herein can contain any of the components and or ranges of amounts of components described herein for the the epoxy resin composition, the thermosetting resin composition or the thermoplastic resin composition and vice-versa any of the epoxy resin composition, the thermosetting resin composition and the thermoplastic resin composition can contain any of the components and or amounts of the components of the hybrid resin

composition described herein.

In one embodiment herein there is provided an article that contains any of the

composition(s) described herein. In one embodiment the article herein can be used in lead free soldering applications and electronic devices, e.g., printed wiring board applications, specifically the article can be a prepreg and/or a laminate. In one specific embodiment there is provided a laminate and/or a prepreg that contains any one or more of the compositions described herein. In one other embodiment there is provided herein a printed wiring board, optionally a multilayer printed wiring board, comprising one or more prepreg(s) and/or a laminate (e.g., either uncured, partially cured or completely cured) wherein said prepreg(s) and/or laminate comprise any one or more of the compositions described herein. In one embodiment there is provided a printed wiring board comprising a prepreg and/or a laminate wherein said prepreg and/or laminate comprises any one of the compositions described herein.

Partial curing as used herein can comprise any level of curing, short of complete cure, and will vary widely depending on the specific materials and conditions of manufacture as well as the desired end-use applications. In one specific embodiment, the article herein can further comprise a copper foil. In one embodiment the article can comprise a printed wiring board. In one embodiment there is provided an FR-4 laminate which comprises a prepreg and/or laminate of the invention. In a more specific embodiment there is provided a printed circuit board comprising an FR-4 laminate, wherein the FR-4 laminate comprises a prepreg or laminate of the invention. In one embodiment herein there is provided a process of making a laminate that contains any of the compositions described herein which process comprises impregnating the respective composition(s) into a filler material, e.g., a glass fiber mat to form a prepreg, followed by processing the prepreg at elevated temperature and/or pressure to promote partial cure to a B- stage and then laminating two or more of said prepregs to form said laminate. In one embodiment said laminate and/or prepreg can be used in the applications described herein, e.g., printed wiring boards.

There is provided herein that any of the compositions described herein are useful for making a prepreg and/or laminate with a good balance of laminate properties and thermal stability, such as one or more of high T_g (i.e. above 130°C), Ta of 330°C and above, t₂₈8 of 5 minutes and above, a flame resistance rating of V-0, good toughness, and good adhesion to copper foil. In recent years T_<j has become one of the most important parameters, because the industry is changing to lead-free solders which melt at higher temperature than traditional tin- lead solders.

In one embodiment herein the compositions described herein can be used in other applications, e.g., encapsulants for electronic elements, protective coatings, structural adhesives, structural and/or decorative composite materials in amounts as deemed necessary depending on the particular application.

In yet a further embodiment herein there is provided a method of making a halogen-free active ester curing agent for thermosetting resins, e.g., epoxy resins, made in one embodiment by the method described in reaction mechanism (A) below:

wherein 2,4,6-tris-morpholinomethyl-l,3-dihydroxybenzene is reacted with 10-ethoxy-10H-9- oxa-10-phospha-phenanthrene (DOP-OEt) and also acetic anhydride to form 2,4,6-tris-DOPO- 1 ,3-dihydroxybenzene.

In one non-limiting embodiment, the method of making the halogen-free active ester curing agent of formula (1) and/or (I V)-(IX) herein can comprise reacting any substituted hydroxyaromatic Mannich-base with any carboxylic anhydride and an alkoxylated phospha- phenanthrene compound in the presence of a hydrocarbon solvent to produce compounds of the general formula (I) and/or (IV)- (IX).

In one non-limiting embodiment herein the method of making the halogen-free active ester curing agent of formula (I) and/or (IV)-(IX) herein can comprise the following general reaction mechanism:

Substituted hydroxyaromatic Mannich-base +

Carboxylic anhydride + DOP-O-alkyl

Wherein the substituted hydroxyaromatic Mannich-base, the carboxylic anhydride and the DOP- O-alkyl are defined in various non-limiting embodiments below.

Substituted hydroxyaromatic mannich base

In one non-limiting embodiment the substituted hydroxyaromatic Mannich-base is selected from one or more of the general formulae (A) and/or (B):

1³ 2'

Where in formula (A) R and R are each independently 1 to 12 carbon atom-containing linear or branched alkyl radicals such as the non-limiting examples of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, 3-heptyl, octyl, 2- ethylhexyl, nonyl, decyl, undecyl, ddecyl, 2-ethylbutyl, 1-methylbutyl, 1 -rnethylpentyl, 1,3- dimethylbutyl, 1,1,3,3-tetramethylbutyl, 1 -trimethylhexyl, isoheptyl, 1 -methylheptyl, 1,1,3- trimefhylhexyl and 1-methylundecyl, and R³ is hydrogen, -OH, or a linear or branched alkyl of from 1 to 6 carbon atoms;

wherein in formula (B) where each R^! is independently selected from morpholine, piperazine, ] -Methylpiperazine, piperidine, pyrrolidine and 2-Pyrrolidinone; R³ is, hydrogen, ~ OH or an alkyl group of from 1 to 6 carbon atoms, more specifically from 1 to about 4 carbon atoms. Carboxylic anhydride:

The carboxylic anhydride may be derived from any carboxylic acid. Examples of such anhydrides are acetic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydiophthalic anhydride, as well as hexahydrophthalic anhydride.

DOP-O-Alkyl:

In one non-limiting embodiment the DOP-O-Alkyl is selected from the general formulae (C):

where R¹ is a linear or branched alkyl group containing from I to 8 carbon atoms, more specifically from 1 to about 4 carbon atoms; each of R² -R⁹ is independently a hydrogen atom or a hydrocarbyl group that may contain on or more heteroatrom such as O, S, N, P or Si provided that not more than 3 of R² - R⁵'" are hydrogen atoms, and each of R^R⁹

independently contains less than 7 carbon atoms.

The halogen-free active ester curing agent of formula (T) and/or (IV)-(IX) produced by one embodiment of the process herein:

where R^1* is hydrogen, a linear or branched alkyl group of from 1 to 8 carbon atoms, more specifically from 1 to about 4 carbon atoms.

where each R* is independently an aliphatic moiety of from 1 to 10 carbon atoms, or phenyl or a substituted phenyl of up to about 12 carbon atoms.

Solvent

The solvent o-xylene indicated in the reaction mechanism above is one embodiment of the invention although the solvent can be any organic, preferably aprotic, solvent. The solvent may be polar or non-polar. Exemplary of polar aprotic solvents are dimethyl formamide, dimethyl acetamide and N-methylpyrrolidone. Preferred solvents are aprotic and non-polar, conveniently aliphatic hydrocarbons, typically heptane, octane, cyclohexane, decalin, mineral oil distillates, such as petroleum ether, ligroin, kerosene, aromatic hydrocarbons such as benzene, toluene, or xylenes, or mixtures of said solvents.

The amounts of (A) and/or (B), carboxylic anhydride, and (C) are used in equimolar amounts but an excess of up to 20%, preferably up to 10% of one or more of (A) and/or (B), carboxylic anhydride and (C) can be useful. The reaction temperature of the above reaction mechanism range from room temperature (e.g., 25°C) up to about 200°C, preferably from 50°C to about 140°C and most preferably from 60°C to about 120°C.

The following examples are used to illustrate the present invention. EXAMPLES

Example 1

Synthesis of composition A - small scale.

Step 1

Synthesis of lO-chioro-lOH-9-oxa-lO-phospha-phenanthrene (POP-CD: DOPO-H (5.0 g, 23.1 mmol) was suspended in chloroform, and to this suspension, PC1₃ (4.7 g, 34.7 mmol) was added under a nitrogen atmosphere. A homogenous solution was observed after 5 minutes of stirring at room temperature. The solution was refluxed for 3 hours. Removal of chloroform led to the formation of a crystalline white powder of DOP-Cl of the formula below. 1H-NMR (300MHz,

CDCI₃, δ, ppm): 7.90-7.84 (m, 2H), 7.60-7.48 (m, 2H), 7.37-7.25 (m, 2H), 7.19-7.10 (m, 2H); ³¹P NMR (121 MHz, CDCI₃, ppm): 134.

Step 2

Synthesis of DQP-QEt: DOP-Cl (5.2 g, 22.16 mmol) from Example 1 was dissolved in toluene to get a homogenous solution. To this solution, triethylamine (3.3 g, 33.2 mmol) was added under a nitrogen atmosphere. To this triethylamine-DOP-Cl solution, ethanol (1.0 g, 23.0 mmol) was added slowly. A white precipitate, formed immediately. The suspension was stirred at this temperature for 2-3 hours. The white precipitate of triethylamine hydrochloride was isolated by filtration and washed with toluene. The removal of toluene gave a colorless gel like product which solidified upon standing overnight at room temperature (4.05 g). ³¹P NMR (121 MHz, CDCl₃, ppm): 130.

Step 3

Synthesis of the 2,4.6-tris-morpholinoniethyl-l,3-dihydroxybenzene: Formaldehyde (16.36 g, 544.95 mmol) and morpholine (47.0 g, 594.95 mmol) were mixed together in Isopropyl Alcohol (IP A) (150 mL). The suspension was heated to reflux and during this time a homogenous solution formed. To this solution resorcinol (20.0 g_s 181,65 mmol) in IPA was added and the resulting clear solution was refluxed for 2 hours. Removal of the solvent resulted in a slurry. The slurry was dissolved in dichloromethane (DCM) and washed with water several times. The organic layer was dried over magnesium sulfate MgS0₄ followed by removal of solvent leaving 68.8g, of white powder of the structure below. ^!H NMR (CDCl₃, 300 MHz): 6.7 (s, 1H), 4.09 (s,

2 H), 3.5 (s, 6H), 3.7 (s, 12H,), 2.5 (s, 12H).

Step 4

Synthesis of final product composition A

DOPO-OEt (8.9 g, 36.8 mmol) synthesized as in Step 2, and 2,4,6-ίΓΪ3^ο ^1ϊηοιηεΐΙτν1-1,3- dihydroxybenzene (5 g, 12.26 mmol) synthesized as in Step 3 were dissolved in o-xylene and heated to 80 °C. To this homogenous solution, acetic anhydride (3.75 g, 36.8 mmol) was added drop wise. The resulting clear solution was heated to reflux under a nitrogen atmosphere. The progress of the reaction was monitored by ³¹P NMR, which showed that after - 8-10 hours the reaction was near completion. The solvent was removed under reduced pressure and the resulting solid was dissolved in DCM and the solution was washed with 1M HC1 four times. The organic layer was dried over MgS0₄ and the DCM was removed under vacuum. The product was a white solid (11.2 g. ³¹P NMR (121 MHz, CDC1₃, ppm : 29-35 (m).

Example 2

Synthesis of composition A - large scale

Step 1

Synthesis of the 2,4,6-tris-morpholinomethyl-l,3-dihydroxybenzene: Formaldehyde (163.6 g, 5.4 mole) and morpholine (474.7 g, 5.4 mole) were mixed together in IPA (850 mL). The suspension was heated to reflux and during this time a homogenous solution formed. To this solution resorcinol (200.0 g, 1.8 mole) in IPA was added and refluxed the resulting clear solution for 2 hours. Removal of the solvent results in a white powder. Yield = 688 g. Ή NMR (CDCl₃, 300 MHz): 6.7 (s, 1H), 4.09 (s, 2 H), 3.5 (s, 6H), 3.7 (s, 12H,), 2.5 (s, 12H).

Step_.2

Synthesis of lO-chIoro-lOH-9-oxa-lO-phospha-phenanthrene:

DOPO-H (9,10-Dihydro-9-oxa-10-phosphaphenanthren 10-oxide) (742.17 g, 3.4 mole) was suspended in chloroform and to this suspension, PC1₃ (565.7 g, 4.1 mole) was added under nitrogen atmosphere. A homogenous solution observed after 15 minutes of stirring at room temperature. The solution was refluxed to 3 hours. During this time a yellow color sticky compound deposited on the bottom of flask. The colorless chloroform solution was carefully decanted to another flask and after removal of chloroform a crystalline white powder of DOP-C1 was obtained. Yield = 741 g. 1H-NMR (300MHz, CDC1₃, δ, ppm): 7.90-7.84 (m, 2H), 7.60-7.48 (m, 2H), 7.37-7.25 (m, 2H), 7.19-7.10 (m, 2H); ³¹P NMR (121 MHz, CDC1₃, ppm): 134.

Step 3

Synthesis of DOP-OEt (6-Ethoxy-6H-dibenz[c,e][l,2]-oxaphosphorin): DOP-C1 (741 g, 3.1 mole) was dissolved in anhydrous xylene (400 mL) to get a homogenous solution. To this solution, triethylamine (353 g, 3.5 mole) was added under nitrogen atmosphere. To this triethylamine-DOP-Cl solution ethanol (161.0 g, 3.5 mole) was added slowly. A white ppt.

formed immediately. The suspension was stirred at this temperature for 2-3 hours. The white ppt. of triethylamine hydrochloride was isolated by filtration and washed thoroughly with xylene. The removal of xylene gave a colorless gel like product which solidifies upon standing overnight at room temperature. Yield= 632.5 g. ³¹P NMR (121 MHz, CDC1₃, ppm): 130.

Step 4

Synthesis of the final composition A, in toluene: DOP-OEt (632 g, 2.5 mole), the 2,4,6-tris- morpholinomethyl-l,3-dihydroxybenzene (351.5 g, 0.86 mole) were mixed in xylene (500 ml). The suspension was heated to 80 °C to get a homogenous solution. Acetic anliydride (439 g, 4.3 mole) was added slowly at 80 °C. The resulting clear solution was heated to reflux under nitrogen atmosphere. The progress of the reaction was monitored by ³¹P NMR, which shows that after - 9-10 hours the reaction reached completion. The solvent was removed under reduced pressure and the resulting colorless solid was dissolved in DCM to wash with IN HC1 (3-4 times) to remove 4-acetyl morpholine. The organic layer was washed with NaHC0₃ to remove the traces of acetic acid. The pH was measured in order to make sure that acetic acid has been removed completely. The DCM layer was dried over MgS0₄ and solvent removed under vacuum to get a white glassy solid. Yield: 697.2 g,. ³¹P NMR (121 MHz, CDC1₃, ppm): 29-35 (m)

Example 3

Synthesis of composition B

2,4,6-tris-morpholinomethyl-l,3-dihydroxybenzene (prepared as in Example 2) (346.0 g, 0.85 mole) and DOPO-H (642.4 g, 2.9 mole) were mixed in mesitylene (500 mL). The suspension was heated at 100 °C to get a homogenous solution. The solution was heated to 150°C for another 1.5 hours and during that time a light pink color precipitate was formed. The reaction was cooled to room temperature and the pink solid was isolated by filtration. The pink solid was thoroughly washed with dichloromethane several times. Intermediate 1 - 340 g. P NMR (121 MHz, DMSO-ίήί, ppm): 35.

This product was than acetylated in the next step. Intermediate 1 (340.0 g) and excess acetic anhydride (200 mL) and 4-(Dimethylamino)pyridine (8.0 g) were placed in 3 neck round bottom flask equipped with reflux condenser and the suspension was heated to reflux under nitrogen atmosphere. After 40-45 min a brown color homogenous solution formed. The reaction mixture was kept at this temperature for 1 hour. The excess of acetic anhydride was distilled out under reduced pressure. The resultant solid was dissolved in dichloromethane (300 mL) and washed with IN HCI (200 mL X 3 times). The resultant dichloromethane layer was further washes with saturated NaHC0₃ (200 mL X 3 times). After that dichloromethane layer was dried over MgS0₄, and the solvent was removed to get a light brown solid 270 g. ³¹P NMR (121 MHz, DMSO-c/6, ppm): 33.

Analysis of composition A and B

LC instrument: Dionex, UHPLC, Ultimate 3000;

Reagents: Water, LC-MS CHROMASOLL ®, Fluka; Acetonitrile (ACN), LC-MS

CHROMASOLL ®, Fluka; Formic acid (FA), eluent additive for LC-MS, Fluka

Column & Packing: Phenomonex, Kinetex, Phenyl-Hexyl 100A, 250 x 4.6 mm, 5μ

Mobile phase: Eluent A- Water 0.05% FA; Eluent B- ACN 0.05% FA; Gradient;

Diluent ACN/Water (1 :1 V/V); Flow rate: 0.7 ml/ min.

Detection: UV operated at 210 nm, PDA 200-450 nm

Injection volume: 5 μΕ; Run time: 40 min; Column temperature: 40°C

MS instrument: Thermo scientific, Exactive plus

Scan range: 100- 1000 m/z; Resolution: 140,000

Vaporizer temperature: 250°C

Typically 10 mg of sample were dissolved in 5 ml ACN and 5 ml of water were added.

Composition A

Two components were identified in approximately 20/80 mass ratio.

80% as two isomers with identical mass.

Composition B

Mainly one component was identified.

00%

Example 4

Laminate preparation and evaluation

The composition A, synthesized in Example 2 was explored as a co-curing agent for the epoxy laminate application The composition A together with phenolic novolac was used to cure multi-functional epoxy resins DEN 438 and EPON 164. All the materials information is listed in Table 1. A varnish formulation was prepared therefrom which had a phosphorous content of 3.0 % and the composition contents are shown in Table 2. The prepared varnish is yellow in color. Table 1. Materials

Trade Name (Producer) General Information Function

SD-1708 (ex Momentive) Phenolic novolac Curing agent

DEN 438 (ex Dow Chemicals) Phenol novolac epoxy Epoxy resin

EPON 164 (ex Momentive) Cresol novolac epoxy Epoxy resin

Dowanol (ex Fluka) 1-methoxy 2-propanol Solvent

2-ml (ex Air Products) 2-methyl imidazole Catalyst

Glass Cloth (ex BGF Industries) E-Glass Reinforcing agent

Copper foil (ex Gould Electronics) JTC, l.O oz./ft Resistance to oxidation in warm and humid environments and for precise etching behavior and others

Table 2. Epoxy laminate formulation with Composition A

The catalyst addition was carefully controlled by adding small incremental amounts of 2-methylimidazole (2-ml) to obtain an optimum varnish gel time of 280 seconds at 171°C according to IPC-TM-650 test 2.3.18. A Differential Scanning Calorimetry (DSC) heating run with 5°C/min up to 300°C was conducted to study the curing behavior of the varnish and the maximum exotherm occurs at around 180°C.

A glass fabric (10.5 10.5 inch) was manually brushed with the varnish on both sides at room temperature and hanged in the hood overnight for slow evaporation of solvent. Prepregs were made by drying the resin coated glass fabric in a preheated air circulated oven at 170°C for 30" (one minute and thirty seconds), which gave a resin flow close to 14.50%. Also, the resin content was controlled to be over 40 - 45 %, which is determined through the difference in weight between the glass fabric and the prepreg. The prepreg properties are shown in the table below: Table 3. Prepreg properties with Composition A as shown in Table 1

A circular stack of 4 prepregs with a diameter of 25 mm was placed between disposable aluminum (Al) plates to study the rheological behavior of the B-stage prepreg by electrically heating the resin to 225°C at 5°C/min in an AR2000ex Rheometer. A continuous controlled strain condition within the linear viscoelastic region of the prepreg was maintained along with the normal force control that accounts for volume changes occurring in the resin with change in temperature.

Based on DSC curing kinetics and rheology curves, the final curing temperature for the laminate was selected above 179°C. Based on the rheology curve, the curing cycle was designed to obtain a good wetting of the glass cloth. At 120-122°C the complex viscosity of the prepreg was at its lowest value and a 50 psi pressure was applied at this minimum viscosity point. The pressure was increased in small steps from 130-160°C and a maximum pressure of 500 psi was applied at 190°C. A laminate was made by stacking together 8 prepregs with a copper foil on the top and bottom of the prepreg stack. The assembly was placed between two stainless steel plates and into a hydraulic press with four sheets of kraft paper below and above the plates. The 8 prepregs were compression molded in the hydraulic press following the cure cycle mentioned above by linearly heating the press to 195°C and the final laminate was isothermally maintained at 195°C for 90 minutes with a pressure of 500 psi and later post-cured the compressed laminate at 21 °C for 15 minutes. The post-curing was performed because a final plateau was observed in the storage modulus after 215°C. The resultant laminate showed a high resin flow and the thickness of the final laminate was from 1.05-1.10 mm (without copper). The laminate was rated as a strong V-0 with a maximum burn time of 4 seconds by following ASTM D3801-10 standard using an Atlas UL-94 burning chamber (V-0 being the highest possible rating). The thermal decomposition temperature of the composite at 5 weight% loss is 365°C as measured by Thermogravinietric Analysis (TGA) at a heating rate of 5°C/min in an inert atmosphere of nitrogen.

Second Laminate preparation with Composition A

Composition A was used as a curing agent together with phenolic novolac (SD-1708) to cure multi-functional epoxy resins DEN 438 and EPON 164. The varnish formulation had phosphorus content of 2.7 % P and is shown in Table 4. The solids content was maintained at 66.67 % with the addition of Dowanol. The varnish had a gel time of 368 seconds at 171°C. A DSC heating run with 10°C/min up to 300°C was conducted to study the curing behavior of the varnish. The maximum exotherm occurs at 204°C for the varnish formulation shown in Table 4.

Table 4. Epoxy laminate formulation containing Composition A

Prepregs were made with this varnish and dried at 165°C for 4Ό0" (four minutes), which gave a resin flow close to 14.0 %. Also, the resin content was controlled to be over 45 - 52 %, which is determined through the difference in weight between the glass fabric and the prepreg. The prepreg gel time was determined by collecting the fusible, thermoplastic resin by crushing the prepreg in a zip-lock bag. The collected resin was placed on the hot-plate at 171°C and the gel time determined. The prepreg properties are shown in the table 5 below:

Table 5. Prepreg properties containing Composition A at B-stage

A circular stack of 4 prepregs with a diameter of 25 mm was placed between disposable Aluminum (Al) plates to study the rheological behavior of the resin by electrically heating to 200°C at 5°C/min in an AR2000ex Rheometer. The onset of gelation occurs at around 110°C and the cross-linking of the epoxy resin was evident with the rapid increase in complex viscosity at around 175°C.

Based on the rheology curve of the B-staged pregreg, the curing cycle was designed to obtain a good wetting of the glass-fiber. Small initial pressure of 10-20 psi was applied at close to 90-100°C for wetting the glass-fiber and pressure was increased in small increments between 135°C-174°C. Small drop (2-8 pressure units) in pressure was observed while the pressure was raised from 50 to 200 psi in the temperature range of 135-174°C. Finally, 200 psi was applied at 195°C and the laminate was isothermally cured for 90 minutes.

The epoxy laminate containing Composition A was ranked as V-0 with a maximum burn time of 7 seconds. The glass transition temperature (Tg) of the multilayer laminate was determined to be 176°C by Dynamic Mechanical Analysis (DMA) in a single-cantilever mode at a ramp rate of 3°C/min. The thermal decomposition temperature of the composite at 5 weight% loss is 412°C as measured by Thermogravimetric Analysis (TGA) at a heating rate of 10°C/min in an inert atmosphere of nitrogen.

Four specimens for the Pressure Cooker Test (PCT) were cut from the epoxy laminate containing Composition A and placed in the pressure cooker for 30 minutes at 121°C and 15 psi. The water uptake of the test coupons was around 0.16-0.23 weight%. The test results are shown in Figure 1. All the test specimens do not exhibit any blistering and were graded as condition 5 according to the IPC test criteria.

Laminate preparation with Composition B

Example 5

Composition B as curing agent

Composition B was used as a curing agent together with phenolic novolac (SD-1708) to cure multi-functional epoxy resins DEN 438 and EPON 164. The varnish formulation had phosphorus content of 2.7 % P and is shown in Table 6. The solids content was maintained at 63.90 % with the addition of Dowanol. The varnish had a gel time of 360 seconds at 171°C. A DSC heating run with 10°C/min up to 300°C was conducted to study the curing behavior of the varnish. The result is shown in Figure 2, which shows that the maximum exotherm occurs at 204°C.

Table 6: Epoxy laminate formulation with Composition B as the curing agent

Prepregs were made with this varnish and dried at 165°C for 2'40", which gives a resin flow close to 7.0-10.0 %. Also, the resin content was controlled to be over 30 - 35 %, which is determined through the difference in weight between the glass fabric and the prepreg. The prepreg gel time was determined by collecting the fusible, thermoplastic resin by crushing the prepreg in a zip-lock bag. The collected resin was placed on the hot-plate at 171°C and the gel time determined. The prepreg properties are shown in the table 6 below:

Table 7. Prepreg properties containing Composition B at B-stage

A circular stack of 4 prepregs with a diameter of 25 mm was placed between the disposable Al plates to study the rheo logical behavior of the resin by electrically heating to 200°C at 5°C/min in an AR2000ex Rheometer in-house. Figure 3 shows the complex viscosity profile of the prepreg with rise in temperature of the B-staged resin system in an oscillatory testing mode. Figure 4 shows the overlay curves for the storage modulus (G'), loss modulus (G") and complex viscosity (]η[) of the B-staged resin system. Based on the Figures 2, 3 and 4, the curing cycle was designed to obtain a good wetting of the glass cloth. A low initial pressure of 10 psi was applied at 90-92°C (the complex viscosity of the prepreg was around 17530-15750 pa-s) and sufficient to wet the glass fabric as studied during the preparation of various experimental epoxy laminates. Subsequent 20 psi pressure was applied at 109-110°C and the pressure was maintained at 20 psi until 130°C. The pressure was again raised to 50 psi at 130°C and 75 psi once the press reached 146°C. A pressure of 100 psi was applied at 166°C and finally a pressure of 220 psi was applied at 195°C. Finally, the press was maintained at 220 psi and 195°C isothermaliy for 90 minutes. The laminate showed a good resin flow and the thickness of the final laminate was close to 1.3 mm (without copper).The laminate was rated as a strong V-0 with a maximum burn time of 7 seconds.

The glass transition temperature of the laminate was 159°C using the DMA method with 3°C/min heating rate as shown in Figure 5. In the pressure cooker test (PCT) the water uptake after 30 minutes was 0.071 and 0.085 weight% respectively. 4 out of 4 samples passed the 20 seconds soldering bath dip test at 288°C. The thermal decomposition of the composite is also shown in Figure 6.

While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the process of the invention but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1 , A compound having the general formula (I)

wherein DOPO is a 9, 10-dihydro-9-oxa-10-phosphenanthrene 10-oxide moiety of the formula

wherein the dashed line represents a bond to the structure of formula (I) above; R is hydrogen, -OC(=0)R*, or -OH, wherein R* is an alkyl group containing from 1 to about 8 carbon atoms or substituted or unsubstituted phenyl; R¹ is an alkyl group of from 1 to 6 carbon atoms or R; and, R² and R³ are each independently selected from -CH₂-DOPO wherein DOPO is as defined, R , - OH, or a moiety of the general formula (III):

wherein R is selected from a bond, a divalent alkylene moiety containing from 1 to about 6 carbon atoms, and a sulphone; R⁵ is selected from hydrogen, -OH and -OC(=0)R*, wherein R* is as defined; and, the dash from R⁴ represents the bond to the structure of general formula (I); provided that when R² is of the general formula (III) and any one or more of R, R¹ and R³ are -OH, then R⁵ is not -OH, and provided that when R³ is of the general formula (III) and any one or more of R, R¹ and R³ are -OH, then R⁵ is not -OH; and,

provided that at least one of R, R^], R², R³ or R⁵ is -OC(=0)R*, and provided that only one of R² or R³ is a moiety of the general formula (III), such that when R² is a moiety of the general formula (III), R is selected from -CH₂-DOPO. R or -OH, and when R is a moeity of the general formula (III), R² is selected from -CH₂-DOPO, R¹ or -OH.

2. The compound of Claim 1 wherein the compound is selected from the formulae (IV)-(VIII):

wherein DOPO and R* are as defined and R is an alkyl of from 1 to about 6 carbon atoms;

wherein DOPO and R* are as defined and R⁶ is an alkyl of from 1 to about 6 carbon atoms;

wherein DOPO and R* are as defined;

(VII) wherein DOPO and R* are as defined; and,

wherein DOPO and R* are as defined, and X is selected from -(CH₂)_n- wherein n is from 1 to 6, sulphone and a bond.

3. The compound of Claim 1 wherein the compound is of the general formula (IX):

wherein R* and DOPO are as defined.

4. A composition comprising a thermosetting resin, a flame retardant effective amount of the compound of Claim 1, and optionally one or more of a co-crosslinker, a curing catalyst, a Lewis acid, a benzooxazine-containing compound, and optionally an inhibitor.

5. The composition of Claim 4 wherein the thermosetting resin is an epoxy resin.

6. The composition of Claim 4 wherien the thermosetting resin is selected from the group consisting of epoxy, polyurethane, polyisocyanates, benzoxazine ring-containing compounds, unsaturated resin systems containing double or triple bonds, polycyanate ester, bismaleimide, triazine, bismaleimide and mixtures thereof

7. A composition comprising a thermoplastic resin, a flame retardant effective amount of the compound of Claim 1, and optionally a co-crosslinker, optionally a Lewis acid, optionally a benzooxazine-containing compound, and optionally an inhibitor.

8. A composition comprising a thermoplastic resin, a thermosetting resin, a flame retardant effective amount of the compound of Claim 1 , and optionally a co-crosslinker, optionally a curing catalyst, optionally a Lewis acid, optionally a benzooxazine-containing compound, and optionally an inhibitor.

9. The composition of Claim 4 which is in the absence of halogen.

10. The composition of Claim 4 wherein the flame retardant effective

amount of the compound of Claim 1 is from about 10 to about 150 parts by weight per 100 parts of the thermosetting resin.

11. Any one of a coating formulation, an encapsulant, a composite, an adhesive, a molding a bonding sheet or a laminated plate compring the composition of Claim 4.

12. An article comprising the composition of Claim 4.

13. The article of Claim 12 wherein said article can be used in lead free soldering applications and electronic devices.

14. The article of Claim 12 wherein the article further comprises a copper foil.

15. The article of Claim 2 wherein said article is a printed wiring board.

16. A prepreg comprising the composition of Claim 4.

17. A laminate or a bonding sheet comprising the composition of Claim 4.

18. A printed wiring board comprising prepreg of Claim 16

19. A printed wiring board comprising the laminate of Claim 17.

20. A process of making a laminate that contains the composition of Claim 5 comprising impregnating the composition into a filler material, to form a prepreg, followed by processing the prepreg at elevated temperature to promote partial cure to a B -stage and then laminating two or more of said prepregs at elevated pressure and temperature to form a laminate.

21. A printed wiring board made by the process of Claim 20.

22. A curing agent for epoxy resins made by the process of Claim 22.