CA2026255A1

CA2026255A1 - Phosphorus-containing copolymers and their use

Info

Publication number: CA2026255A1
Application number: CA002026255A
Authority: CA
Inventors: Alfred Renner
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1989-09-28
Filing date: 1990-09-26
Publication date: 1991-03-29
Also published as: EP0420811A2; EP0420811A3; JPH03124728A; KR910006367A

Abstract

K-17766/+

Phosphorus-containing copolymers and their use Abstract Phosphorus-containing copolymers obtainable by reacting an epoxide compound with a dialkyl pentaerythrityl diphosphite of the formula I

Description

2 0 ~

K-17766/+

Phosphorus-containin~ copolymers and their use The invention relates to phosphorus-containing copolymers obtainable by reacting epoxide compounds with certain diaL~yl pentaerythrityl diphosphites, to a process for their preparation and to their use, in particular as fire-retarding additives for epoxy resins or as phosphorus-containing epoxy resins which, after curing, afford fireproof, crosslinked produsts having good properties.

DiaLlcyl and diaryl pentaerythrityl diphosphites, i.e. 3,9-dialkoxy-2,4,~,10-tetraoxa-3,9-diphosphaspiro[5,5]undecanes and 3,~-diaryloxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro-~5,5]undecanes, respectively, are known. US Patent 2,847,443 describes, for exarnple, reaction products of triarylphosphites with pentaerythritol, including also diaryl pentaerythrityl diphosphites, which are used as stabilizers for halogen-containing polymers or elastomers, or as oil additives. U~ Patent 3,047,608 describes a process for the preparation of tertiary phosphites of high-boiling alcohols. As well as a large number of phosphites, the preparation of diaL~yl pentaerythrityl diphosphites is also mentioned, and also the further conversion of these compounds into polymers in the presence of a catalyst, for example by reaction with suitable dihydric alcohols. The phosphites or diphosphites thus prepared are alleged to be suitable for use as stabilizers for polyolefins or polyurethanes, as fire-retarding agents for cellulose and cellulose esters, or as a curing agent for epoxy resins, none of these applica$ions being disclosed.

British Patent 1,439,092 describes sterically hindered phenol pentaerythritol phosphonates which are prepared, for example, by reacting pentaerythrityl diphosphites with derivatives of sterically hindered phenols. These phosphonates are suitable for use as phenolic antioxidants for a large number of different types of plastics, including also epoxy resins.

Japanese Prelirninary Published Specification 53-71,153n8 describes compositions of matter containing chlorine-containing plastics, such as PVC, a phosphite, for example a dialkyl pentaerythrityl diphosphite, a monoaLkyl or dialkyl hydrogenphosphi~e and a low-molecular weight epoxy Tesin.
;

. .

2~2~ 5 Japanese Preliminary Published Specification 46-20,825nl descAbes the reaction of epoxide compounds having at least 2 epoxide groups with compounds containing at least 2 hydrophosphoryl or phosphonyl groups in the presence of a catalyst selected from the group comprAsing alkali metals, alkaline earth metals and amalgams and also organo-metallic compounds of these metals. In one example bisphenol A diglycidyl ether is reacted with an equimolar amount of pentaerythAtyl diphosphite in the presence of sodium as catalyst to give a phosphorus-containing, incombustible polymer. Polymers obtained by reacting dialkyl phosphites, including pentaerythrityl diphosphite, are not, however, capable of meeting the requirements for plastics, particularly in respect of stability to water.

The present invention relates to phosphorus-containing copolymers obtainable by reacting an epoxide compound with a dialkyl pentaerythrityl diphosphite of the formula I

R10--P C P O* (I) /\ /

in which Rl and R2 independently of one another are a Cl-C4alkyl group.

DiaLkyl pentaerythrityl diphosphites of the forrnula I are known, for example from US
Patent 3,047,608 mentioned above. They are generally prepared by reacting a suitable trialkyl phosphite with pentaerythritol in the presence of a catalyst, for example dialkyl phosphite, sodium alcoholates or tertiary amines.

It has now been found that particularly good, monomeric products are obtained if the reaction is carAed out in toluene or xylene. The invention therefore also relates to a process ~or the preparation of the dialkyl pentaerythAtyl diphosphites of the formula I by transesterAfying a tAalkyl phosphite in which the alkyl groups contain 1-4 C atoms with pentaerythAtol in the presence of a catalyst, which compAses carrying out the transesterification at reflux temperature in toluene or xylene and rernoving the alkanol forrned duAng the reaction by distillation as an azeotrope with toluene or xylene.

The reaction can be carried out using one single trialkyl phosphite or using a mixture of trialkyl phosphites. Suitable trialkyl phosphites are compounds in which the alkyl groups 2 ~

are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and tert-butyl. The alkanol/toluene or alkanol/xylene azeotropic mixture formed during the reaction can suitably be distilled off via the head of a column. The monomeric diaL~yl pentaerythrityl diphosphite thus obtained can be isolated, for example after it has crystallized out from the reaction mixture, or can immediately be reacted further in solution to give a suitable copolymer. Since these monomers themselves have only a limited stability at roomtemperature and polymerize, the last-mentioned process is particularly appropriate.

Catalysts which are particularly suitable for the preparation of the diphosphites are C1-~4diaLIcyl phosphites, sodium alcoholates having 1-4 C atoms or triethylamine. If the diaL~yl phosphites or the sodium alcoholates are used as catalysts, it is preferable to employ compounds having the same aL~cyl group as the alkyl group of the trialkylphosphite starting material which is transesterified with pentaerythritol. The catalyst is preferably employed in an amount of 0.5-5 % by weight, in particular 1-3 % by weight, relative to the total amount of the trialkyl phosphite and of the pentaerythritol.

In the preparation of the diphosphites of the formula I it is preferable to react pentaerythritol with one single Irialkyl phosphite, so that diphosphites of the formula I are forrned in which the radicals R1 and R2 are identical. Diphosphites in which R1 and R2 are n-butyl and especially methyl are particularly suitablF.

In principle, any desired epoxide compound can be employed in the preparation of the phosphorus-containing copolymers according to the invention. It is possible to use either mono-epoxides or di-epoxides or poly-epoxides. It is preferable to employ 0.05 to S mol, especially 0.1 to 2.5 mol, of diphosphite per mole of the epoxide compound. Depending on the ratio between the epoxide compound and the diphosphite, it is thus possible to obtain copolymers having very varying properties, for example varying molecular weights or phosphorus contents.
If an excess of up to one equimolar quantity of the diphosphite is used, thermoplastic oligomers or polymers which have a relatively high phosphorus content and are suitable for use as fire-retarding additives for plastics, in paTticular for epoxy resins, are formed.
The use of such copolymers instead of the unreacted diphosphite as a f1re-retarding agent brings the advantage of substantially simpler and more reliable handling, since the spiro-diphosphites polymerize on their own or with epoxides in a strongly exothermic reaction and in a manner hard to control.

', 2 ~ 2 ~ 2 ~3 ~

If an excess of a di-epoxide or poly-epoxide compound relative to the diphosphite, for example 2-10 mol of epoxy-comonomer per mole of diphosphite~ is employed in the reaction, so-called advanced epoxy resins containing chemically attached phosphorus are obtained. After curing, these epoxy resins afford crosslinked products which areincombustible or self-extinguishing and do not contain halogen atoms. As is known, the disadvantages entailed by halogen-containing resins which have been treated so as to be fire-resistant, for example corrosion damage, are undesirable, particularly in electrical engineering and electronics.

The copolymers according to the invention are suitably prepared by heating the reaction mixture at a temperature of 80 to 220C, preferably 100 to 200C. If appropriate, the reaction can be carried out in a suitable solvent. Examples of suitable solvents are toluene and xylene. After the completion of the reaction the solvent is removed by distillation.
Preferably, however, the copolymers according to the invention are prepared by heating the epoxide and the diphosphite in the absence of a solvent. The reaction time can vary considerably, depending on the product desired, for example from a few minutes in the case of the so-called advanced reactive epoxy resins up to several hours, for example 15 hours or more, in the preparation of thermoplastic copolymers having a high phosphorus content. The invention therefore also relates to a process for the preparation of the copolymers according to the invention.

The preparation of the copolymers according to the invention is preferably effected in a reaction medium in which chlorine-containing plastics, such as PVC, are not present.
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The copolymerization, according to the invention, of epoxide compounds with the spiro-diphosphites of the formula I proceeds, according to 31P-NMR with a change in valency from pm to pv and with opening of a dioxaphosphacyclohexane ring in the diphosphite, so that phosphorus is thus incorporated chemically into the copolymers in the form of phosphonate. A reaction of this type between diphosphites and epoxide compounds could not have been foreseen.

In a preferred embodiment of the present invention the copolymers according to the invention are prepared by reacting mono-epoxides with the disphosphites. Preferred mono-epoxides are alkyl glycidyl ethers, for example butylhexyl or ethylhexyl glycidyl ether, aryl glycidyl ethers, for example phenyl, cresyl or p-t-butylphenyl glycidyl ether, or 2~2~j epoxidized ole~lns, for example styrene oxide or cyclohexene oxide.

Mono-epoxides which are particularly preferred are n-butyl glycidyl ether, cyclohexene oxide, styrene oxide or, in particular, phenyl glycidyl ether. Phosphorus-containing copolymers according to the invention which are prepared by reacting one mole of the diphosphite per mole of the mono-epoxide are particularly preferred.

In another preferred embodiment of the present invention the copolymers according to the invention are prepared by reacting epoxy resins with the disphosphites.

In principle, any compound customary in the technology of epoxy resins can be employed as the epoxy resin in the reaction. Epoxy resins containing on average at least two groups per molecule are preferred.

The following are examples of epoxy resins:

I) Polyglycidyl and poly-(~-methylglycidyl) esters obtainable by reacting a compound having at least two carboxyl groups in the molecule with epichlorohydrin or ~-methyl epichlorohydrin, respectively. The reaction is appropriately carried out in the presence of bases.

Aliphatic polycarboxylic acids can be used as the compound having at least two carboxyl groups in the molecule. Examples of these polycarboxylic acids are succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azeleic acid or dimerized or trimerized linoleic acid.

It is also possible, however, to employ cycloaliphatic polycarboxylic acids, for example tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid or 4-methylhexahydrophthalic acid.

It is also possible to use aIomatic polycarboxylic acids, for example phthalic acid, isophthalic acid or terephthalic acid.

II) Polyglycidyl or poly-(~-methylglycidyl) ethérs obtainable by reacting a compound having at least two free alcoholic hydroxyl groups and/or phenolic hydroxyl groups with a suitably substituted epichlorohydrin under alkaline conditions, or in the presence of an , 2~2~5 acid catalyst followed by subsequent treatment with alkali.

Ethers of this type are derived, for example, from acyclic alcohols, such as ethylene glycol, diethylene glycol and higher poly-(oxyethylene) glycols, propane-1,2-diol or poly-(oxypropylene) glycols, propane-1,3-diol, butane-1,4-diol, poly-(oxytetramethylene) glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, l,l,l-trimethylol-propane, pentaerythritol, sorbitol and polyepichlorohydrins.

However, they are also derived, for example, from cycloaliphatic alcohols, such as 1,4-cyclohexanedimethanol, bis-(4-hydroxycyclohexyl)-methane or 2,2-bis-(4-hydroxy-cyclohexyl)-propane, or they contain aromatic nuclei, such as N,N-bis-(2-hydroxyethyl)-aniline or p,p'-bis-(2-hydroxyethylamino)-diphenylmethane.

The epoxide compounds can also be derived from mononuclear phenols, for example resorcinol or hydroquinone; or they are based on multinuclear phenols, for example bis-(4-hydroxyphenyl)-methane, 4,4'-dihydroxybiphenyl, bis-(4-hydroxyphenyl) sulfone, 1,1,2,2-tetrakis-(4-hydroxyphenyl)-ethane, 2,2-bis-(4-hydroxyphenyl)-propane or 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane, and are derived from novolaks obtainable by the condensation of aldehydes, such as formaldehyde, acetaldehyde, chloral or furfuraldehyde, with phenols, such as phenol, or with phenols which are substituted in the nucleus by chlorine atoms or Cl-Cgalkyl groups, for example 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol, by condensation with bisphenols as described above.

III) Poly-(N-glycidyl) compounds obtainable by dehydrochlorination of the reaction products of epichlorohydrin with amines containing at least two amine hydrogen atoms.
Examples of these amines are aniline, n-butylamine, bis-(4-aminophenyl)-methane,m-xylylenediamine or bis-(4-methylaminophenyl)-methane.

The poly-(N-glycidyl) compounds also include, however, triglycidyl isocyanurate,N,N'-diglycidyl derivatives of cycloaLkyleneureas, such as ethyleneurea or 1,3-propylene-urea, and diglycldyl derivatives of hydantoins, such as 5,5-dimethylhydantoin.
;

IV) Poly-(S-glycidyl) compounds, for example di-S-glycidyl derivatives derived from dithiols, for example ethane-1,2-dithiol or bis-(4-mercaptomethylphenyl) ether.

V) Cycloaliphatic epoxy resins, for example bis-(2,3-epoxycyclopentyl) ether, 2,3-epoxy-.~

2 ~

cyclopentyl glycidyl ether, 1,2-bis-(2,3-epoxycyclopentyloxy) ethane, 3,4-epoxycyclo-hexylmethyl 3',4'-epoxycyclohexanecarboxylate or bis-(3,4-epoxycyclohexylmethyl)esters of aliphatic dicarboxylic acids, such as bis-(3,4-epoxycyclohexylmethyl) adipate.

It is also possible, however, to use epoxy resins in which the 1,2-epoxide groups are attached to various hetero atoms or functional groups; these compounds include, for example, the N,N,O-triglycidyl derivatives of 4-aminophenol, the glycidyl ether/glycidyl ester of salicyclic acid, N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin or 2-glycidyloxy- 1 ,3-bis-(5,5-dimethyl- 1 -glycidylhydantoin-3-yl~-propane.

It is preferable to use epoxy resins which have an epoxide content of 2 to 10 equivalents/lcg and which are glycidyl ethers, glycidyl esters or N-glycidyl derivatives of aromatic, heterocyclic, cycloaliphatic or aliphatic compounds.

Epoxy resins which are particularly preferred are polyglycidyl ethers of alicyclic alcohols, such as 1,1 ,l-trimethylolpropane, bisphenols, for example 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A) or bis-(4-hydroxyphenyl)-methane (bisphenol F), or novolaks formed by reacting formaldehyde with a phenol, and also N-glycidylated aromatic amines, especially tetraglycidylated bis-(4-aminophenyl)-methane. Epoxy resins which are very particularly suitable are bisphenol A diglycidyl ether, epoxy-novolaks or glycidyl ethers of 1,1,1-trimethylolpropane. It is particularly preferable to prepare copolymers by reacting bisphenol A diglycidyl ethers, epoxy-novolaks or glycidyl ethers of 1,1,1-trimethylol-propane with dimethyl pentaerythritol diphosphite.

0.1 to 1 mol of diphosphite per epoxide equivalent of the epoxy resin is preferably employed in the reaction of epoxy resins with the diphosphites. It is particularly preferable to choose the amounts of the diphosphite and of the epoxy resin so that a phosphorus-containing epoxy resin having 2 to 10 % by weight of phosphorus is -formed.

As stated earlier in the text, the copolymers according to the invention are suitable for use as fire-retarding additives for plastics, in particular for epoxy resins. The invention therefore also relates to compositions of matter containing (a) a phosphorus-containing copolymer according to the invention and (b) an epoxy resin. Copolymers having a high phosphorus content, for example having at least 10 % by weight of P, are particularly suitable as component (a). Examples of suitable components (b) of the compositions of matter according to the invention are all the epoxy resins described earlier in the text. The 2 ~

compositions of matter according to the invention can be con~erted into crosslinked products by means of the usual curing agents for epoxy resins. The relative amounts of the components (a) and (b) in the compositions of matter are preferably so chosen that the crosslinked product obtained after curing is incombustible or self-extinguishing.

As mentioned, phosphorus-containing epoxy resins are obtained if an excess of epoxy resin relative to diphosphite is used in the preparation of the copolymers according to the invention. The invention therefore also relates to curable compositions of matter containing (a) a phosphorus-containing epoxy resin according to the invention and (c) a curing agent for epoxy resins.

Examples of curing agents which may be mentioned are the customary curing agents for epoxy resins, including the aliphatic, cycloaliphatic, aTomatic and heterocyclic amines, such as bis-(4-aminophenyl)-methane, aniline/formaldehyde Tesins, bis-(4-aminophenyl) sulfone, propane- 1,3-diamine, hexamethylenediamine, diethylenetriamine, triethylene-tetramine, 2,2,4-trimethylhexane-1,6-diamine, m-xylylenediamine, bis-(4-aminocyclo-hexyl)-methane, 2,2-bis-(4-aminocyclohexyl)-propane and 3-aminomethyl-3,5,5-tri-methylcyclohexylamine (isophoronediamine), polyauninoamides, for example those formed from aliphatic polyamines and dimerized or trimeriæd fatty acids, polyphenols, such as resorcinol, hydroquinone, 2,2-bis-(4-hydroxyphenyl)-propane and phenol/aldehyde resins, polythiols, such as the polythiols obtainable commercially under the name "thiokols", polycarboxylic acids and anhydrides thereof, for example phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, hexachloroendomethylene-tetrahydrophthalic anhydride, pyromellitic dianhydride, benzophenone-3,3,4',4'-tetra-carboxylic dianhydride, the acids of the abovementioned anhydrides and also isophthalic acid and terephthalic acid. It is also possible to use curing agents having a catalytic action, for example tin salts of aLkanoic acids (for example tin octanoate) and Friedel-Crafts catalysts, such as boron trifluoride and boron trichloride and complexes and chelates thereof which are obtained by reacting boron trifluoride ~ith, for example, amines or 1,3-diketones. The cyanoguanidines according to EP-A 306,451 and EP-A 310,545 are also suitable curing agents.

Preferred curing agents are aromatic amines, in particular bis-(4-aminophenyl)-methane or bis-(4-aminophenyl) sulfone, boron trifluorideiamine complexes, in particular the BF3/ethylamine complex, dicyandiamide, the oligomeric cyanoguanidines according to EP-A 306,451 and polyaminoamides.

2~2~2'~

The amount of curing agent employed depends on the chemical nature of the curing agent and on the properties desired in the curable mixture and the cured product. The maximum amount can be deterrnined easily. If the curing agent is an amine, 0.75 to 1.25 equivalents of amine hydrogen per 1 epoxide equivalent are normally employed. If polycarboxylic acids or anhydrides thereof are employed, 0.4 to 1.1 equivalents of carboxyl group or anhydride group are generally used per 1 equivalent of epoxide group. If polyphenols are employed as the curing agent, it is appropriate to employ 0.75 to 1.25 phenolic hydroxyl groups per 1 epoxide equivalent.

Curing agents having a catalytic action are generally employed in amounts of 1 to 40 parts by weight per 100 parts by weight of epoxy resin.

If desired, active thinners, for example styrene oxide, butyl glycidyl ether, 2,2,4-trimethyl-pentyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether or glycidyl esters of synthetic, highly branched, mainly tertiary, aliphatic monocarboxylic acids, can be added to the curable mixtures in order to reduce the viscosity.

In addition, curing accelerators can be employed in the curing operation; examples of such accelerators are tertiary amines, salts or quaternary ammonium compounds thereof, for example benzyldimethylamine, 2,4,6-tris-(dimethylaminomethyl)-phenol, l-methyl-imidazole, 2-ethyl-4-methylimidazole, 4-aminopyridine and tripentylamrnonium phenate;
or alkali metal alcoholates, for example sodium alcoholates of 2,4-dihydroxy-3-hydroxy-methylpentane. The curing of tbe mixtures according to the invention is appropriately carried out within the temperature range from 50C to 300C, preferably 80-250C and particularly 120-200~.

If desired, curing can also be carried out in 2 stages by first terminating the curing reaction prematurely or carrying out the first stage at a fairly low temperature, in the course of which a pre-condensate (so-called "B-stage") which is s~ill fusible and/or soluble and curable is obtained from the epoxide component and the curing agent. A pre-condensate of this type can serve to prepare prepregs, compression moulding materials or sintering powders, for example.

The telm "curing" as it is used here, means the conversion of the soluble, either liquid or fusible, polyepoxides into solid, insoluble and infusible, three-dimensionally crosslinked 2 ~

products or materials, as a rule with simultaneous shaping to give shaped articles, such as castings, pressed articles and laminates, and to give impregnations, coatings, paint films or glued joints.

The curable mixtures according to the invention can also contain suitable plasticizers, such as dibutyl phthalate, dioctyl phthalate or tricresyl phthalate.

As further conventional additives, the mixtures according to the invention can also contain extenders, fillers and reinforcing agents, for example coal-tar, bitumen, textile fibres, glass fibres, asbestos fibres, boron fibres, carbon fibres, mineral silicaees, mica, powdered quartz, hydrated aluminium oxide, bentonites, wollastonite, kaolin, silica aerogels or metal powders, for example aluminium powder or iron powder, and also pigments and dyes, such as carbon black, oxide colours and titanium dioxide, thixotropic agents, flow control agents, such as silicones, waxes and stearates, some of which are also used as mould release agents, adhesion promoters, antioxidants and light stabilizers The mixtures according to the invention can be used, for example, as adhesives, adhesive films, patches, matrix resins, paints or sealing compositions or, quite generally, for the preparation of cured products. They can be used in a formulation adapted to suit each particular field of application, in an unfilled or filled state, for example as paints, coating compositions, lacquers, compression moulding materials, dipping resins, casting resins, impregnation resins, lamination resins, matrix resins and adhesives.

The compositions of matter according to the invention are particularly suitable for use as casting resins and impregnation resins for the production of shaped articles or prepregs, laminates and composites having self-extinguishing properties. The invention also relates to crosslinked products obtainable by curing the compositions of matter according to the invention by means of a curing agent for epoxy resins and to crosslinked products obtainable by curing the curable compositions of matter according to the invention.

The following examples illustrate the invention.

, J J ~

xample 1: PreParation of monomeric, crvstalline 3,9-dimethox~Phospha-2.4.8.10-tetraoxaspiror5,5 (dimethvl pentaerythritYI diphosphite) 372.8 g (3 mol) of trimethyl phosphite, 5.44 g (0.0495 mol) of dimethyl phosphite, 204.2 g (1.5 mol) of pentaerythritol and 1200.0 ml of toluene are heated, with stirring, to the boil in a 2.5 1 stirred flask equipped with a thermometer and a column (L = 55 cm; d = 3 cm), packed with small wire netting cylinders (h = 3 mm;
d=3mm).

260 g of a distillate consisting of 72.23 % of methanol and 27.77 % of toluene are taken of~, between 60 and 62C at the head of the column and at an internal temperalure of 93-100C in the course of 5 hours. A-fter a reaction time of 3 hours the pentaerythritol has completely dissolved. After cooling, a large amount of white crystals are formedovernight; this is filtered off with suction and washed with cold toluene and then with hexane and dried in a stream of dry air at 35C. Yield: 222.7 g, corresponding to 58 % of theory. M.p. = 121.1C.

Elementary analysis: Calculated Found:
for C7Hl4O6P2:
% C: 32.83 32.89 % H: 5.51 5.54 % P: 24.19 24.15 Molecular weight: 256 255 (GPC) Purity (Mettler TA 3000) 98.34 %
According to 3lP-NMR the phosphorus is entirely in the ~ivalent form.

When the product is heated above its melting point a glossy polymer is formed in a strongly exothermic reaction (~H = 389.6 J/g). Even when stored at room temperature the crystals become tacky and are converted into oily to resinous products.

xample 2: Preparation of 3,9-dibutoxv~hospha-2 4.8~10-tetraoxasPiror5.5lundecane-(dibutvl pentaervthritvl diphosphite) 158.2 g of tri-n-butyl phosphite (95 % pure), 5.0 g of di-n-butyl phosphite, 40.8 g of pentaerythritol and 500 ml of xylene are heated, with stirring, to the boil under a distillation column.

337.5 g of distillate which passes over at 75-80C, has refractive indices ~ of between 1.435 and 1.484 and contains a total of 92.1 g of n-butanol are taken off at the head of the column in the course of 1() hours. Since the product does not crystallize out even at a low temperature, the solvent is distilled off on a rotary evaporator at 80C/15-0.1 mm Hg ~2kPa-13 Pa). The residue is 108 g of a colourless oil having a viscosity of 58.4 mPas at 25C and a lefractive index of 1.4680 at 25C.

Elementary analysis: Calculated Found:
for Cl3H26o6p2:
% C: 46.89 47.18 %H: 7.70 7.95 % P: 18.21 17.00 Copolvmer formed from spiro~diphosphite according to Example 1 and PhenYI ~lycidvl ether 4.491 g (0.03 mol) of phenyl glycidyl ether and 7.68 g (0.03 mol) of spiro-diphosphite according to Example 1 are melted together and heated at 160C for 12 hours in a closed ampoule. The viscous resin still contains 0.16 epoxy equivalent per kg. Mn is found to be 1640 and Mw 9170 by m4eans of gel permeation chromatography .

Furthér heating at 200C for 10 hours gives a brown, solid polymer which has a glass transition temperature of 58C and is soluble in tetrahydrofuran and dimethylformamide.

~2~

Elementary analysis: Calculated Found:
for Cl3H26o6p2:
% C: 47.29 47.60 % H: 6.42 6.30 % P: 15.27 15.05 Mn tGPC) = 3420 Mw (GPC) = 403800 xample 4: Copolymer formed from bisphenol A di~lYcidYl ether and sPiro-diPhosphite accordin to Example 1 (molar ratio 1:1) 7.68 g (0.03 mol) of spiro-diphosphite according to Example 1 and 10.48 g (0.03 mol) of bisphenol A diglycidyl ether (epoxide equivalent weight = 174.8) are copolymeri~ed at 120C for 3 hours, at 150C for 2 hours at 170C for 2 hours and at 200C for 8 hours. The amount of heat evolved is 463 J/g and the peak temperature is 228C (Mettler TA 3000). A glassy c~polymer having a glass transition temperature of 35.8C and a softening point, measured on a Kofler bench, of 84C is obtained.
n (GPC) = 1.37 x 104, Mw (GPC) = i.43 x 106.
xample S: CopolYmer formed from bisphenol A di~lYcidvl ether and spiro-diphosphite according to Example 1 (molar ratio 2: 1) 10.24 g (0.04 mol) of spiro-diphosphite according to Example 1 and 6.96 g (0.02 mol) of bisphenol A diglycidyl ether (epoxide equivalent weight = 174.8) are copolymerized using the temperature programrne of Example 4.
~H = 400 J/g, Tm v~ = 207C, Mn (GPC) = 1.76 x 104, Mw (GPC) = ~.64 x 105, Tc = 28.1C, softening point = 77C.

Example 6: Phosphorus-containin~ ePoxY resin A
1000 g of an epoxy resin based on bisphenol A which is liquid at room temperature and has an epoxide equivalent weight of 190 are heated at 170C under a nitrogen atmosphere.
143.67 g of spiro-diphosphite (according to Fxample 1) are introduced in portions, with stirring, in the course of 45 minutes and the mixture is heated at 170C for a further lS
minutes and cooled to room temperature. A dark brown resin containing 3.0 % by weight of P and having an epoxide equivalent weight of 245, Mn (GPC) = 506, Mw (GPC) = 579 2~2~2'.-i~

is obtained.

Curin,. experiments FormulationNo. 6a 6b 6c Phosphorus-containing resin A (g) 17.5 21.4 22.5 Bisphenol A diglycidyl ether (epoxide equivalent weight: 190) 4.0 4,4'-Diaminodiphenylmethane (g) 4.55 FormulationNo. 6a 6b 6c 4,4'-Diaminodiphenyl sulfone (g) - 6.2 BF3/ethylamine complex (g) - - 2.5 Curing at 125C for 2 hours, at 160C for 2 hours and at 180C for 2 hours givesfault-free, brown, tough sheets.

FormulationNo. 6a 6b 6c TG (Metler TA 3000) (C) 149 160 140 Water absorption (%) after 4 days at 25C: 0.41 0.61 0.47 after 1 hour at 100C: 0.47 0.67 0.84 Loss in weight (TGA) ~ % at C 270 290 280 lû % at C 305 315 31û
Flammability as specified in Example 7: Phosphorus-containing epoxv resin B
1000 ~ of an epoxy-novolak which is viscous at room temperature and has an epoxide equivalent weight of 179.2 are reacted with 144.9 g of spiro-diphosphite according to Example 1 for 1 hour at 175C. This gives a dark brown resin ontaining 3.04 % byweight of P and having a viscosity of 256.4 mPas at 80C, an epoxide equivalent weight of 241, MJ, (GPC) = 486 und Mw (GPC) = 634.

Curing is carried out as in Example 6.

2'~

Formulation No. 7a 7b 7c Phosphorus-containing resin A (g) 23.0~ 23.04 23.04 Epoxy-novolak (epoxide equivalent weight 179.2) 5.0 5.0 10.00 4,4'-Diaminodiphenylmethane (g) 6.33 4,4'-Diaminodiphenyl sulfone (g) - 7.9 BF3/ethylamine complex (g) - - 0.8 % by weight of P (relative to resin + curing agent) 2.0 1.92 2.0 Formulation No. 7a 7b 7c TG (Mettler TA 3000) (C) 147.5 144.1 127.8 Water absorption (%) after 4 days at 25C: 0.35 0.36 0.39 after 1 hourat 100C: 0.39 0.59 0.62 Loss in weight (TGA) 5 % at C 270 295 315 10 % at C 310 320 340 Flammability as specified in llL 94 VO VO VO

Example 8: Phosphorus-containing epox~ resin C
70.0 g of N,N'-tetraglycidyl diaminodiphenylmethane are reacted with 30.0 g of spiro-diphosphite according to Example 1 for 15 minutes at 170C. This gives a brown copolymer having an epoxide equivalent weight of 256 and a phosphorus content of 7.25 % by weight.

100 parts by weight of carbon fibre prepreg, Fiberdux(~) 914 (Ciba-(3eigy) are modified with 7.2 parts by weight of the above copolymer. Carbon fibre laminates are compression-moulded from 3 layers of the modified prepreg and 3 layers of the unmodified prepreg for 2 hours at 175C and 7 bar, and the product is subsequently cured for 4 hours at 190C.

2 ~

Properties: Laminate obtained from Fiberdux(~) 914 non-modified modified Thickness (mm) 0.85 0.55 Fibre volume (%) 57.0 57.0 TG (TMA) (C) 197 210 Laminate obtained from Fiberdux(~) 914 non-modified modified Interlaminar shear strength MPa at 25C 71 64 MPa at 120C 51 51 nexural strength (DIN 29,971) MPa 765 650 Flexural modulus (DIN 29,971) GPa 63.0 59.1 Water absorption after 14 days at 71 C (%) 2.0 2.3 Flammability as specified in FAR 25,853a:
Burning distance (mm) after 12 seconds flame tTeatment 140 61 Extinction after seconds 19 8 Burning distance (mm) after 60 seconds flame treatment 230 160 Extinction after seconds 45 42 Flame temperature (C) 910 920 Example 9: Phosphorus-containing el?oxY resin D

473.7 g of a technical triglycidyl ether of trimethylolpropane having an epoxide equivalent weight of 121 and a viscosity of 183 mPa.s are heated at 160C, with stirring. 126.3 g of spiro-diphosphite according to Example 1 are introduced in portions and the mixture is left to react further for 2 hours at 170-175C. This gives 583.90 g of a pale yellow resin having 2 ~ ;3 a phosphorus content of 5.0 %, an epoxide equivalent weight of 204 and a viscosity of 2.38Pa.s. Mn=522,Mw=970 If 100 g of the above phosphonylated resin, 100 g of Al(OH3) and 78 g of a polyaminoamide curing agent (Ciba-Geigy HV 953 U) are mixed and cured at 40C for 16 hours and at 100C for 3 hours, moulding ar~icles are obtained which are incombustible as specified in UL 94 (V-O; after-burn time: 0 seconds).
xample 10: The use of a phosphorus-containin~o~ coPolymer as a fire-retardin~
a~ent for epox~ resins Example No. 10a 10b Copolymer according to Exan~ple 4 (g) 5.95 5.95 6.8 Diglycidyl ether of bisphenol A (g) 12.05 11.55 13.20 4,4'-Diaminodiphenylmethane (g) 8.16 Cyanoguanidine/dicyandiamide curing agent 1) (g) - 3.00 4,4'-Diaminodiphenyl sulfone (g) - - 11.28 Curing at 125C for 2 hours, at 160 for 2 hours and at 180C for 2 hours _ _ _ Glass transition temperature (C) 119 134 126 Water absorption (%) 4 days at 25C 0.31 0.49 0.42 1 hour at 100C 0.75 0.74 1.16 DTA: 5 % loss in weight at C 250 285 285 10 % loss in weight at C 390 360 320 Combustibility as specified in UL 94; stage VO VO VO

Powder mixture composed of 75 parts by weight of an oligomeric cyanoguanidine ofthe formula 2 0 ~ ~ 2 ~ ~

N N

113C~--NH--g--NH~3 ~
prepared in accordance with Example 3 of EP-A 306,451, and 25 parts by weight ofdicyandiamide.

Claims

1. A phosphorus-containing copolymer obtainable by reacting an epoxide compound with a dialkyl pentaerythrityl diphosphite of the formula I

(I), in which R1 and R2 independently of one another are a C1-C4alkyl group.

2. A copolymer according to claim 1, in which R1 and R2 are identical.

3. A copolymer according to claim 1, in which R1 and R2 are n-butyl or methyl.

4. A copolymer according to claim 1, wherein 0.05 to 5 mol of diphosphite are employed per mole of the epoxide compound.

5. A copolymer according to claim 1, wherein the epoxide compound is a mono-epoxide.

6. A copolymer according to claim 5, wherein the mono-epoxide is an alkyl glycidyl ether, an aryl glycidyl ether or an epoxidized olefin.

7. A copolymer according to claim 6, wherein the mono-epoxide is n-butyl glycidyl ether, phenyl glycidyl ether, cyclohexene oxide or styrene oxide.

8. A copolymer according to claim 5, wherein one mol of diphosphite is employed per mole of mono-epoxide.

9. A copolymer according to claim 1, wherein the epoxide compound is an epoxy resin.

10. A copolymer according to claim 9, wherein the epoxy resin has an epoxide content of 2 to 10 equivalents/kg and is a glycidyl ether, glycidyl ester or N-glycidyl derivative of aromatic, heterocyclic, cycloaliphatic or aliphatic compounds.

11. A copolymer according to claim 10, wherein the epoxy resin is a bisphenol A
diglycidyl ether, a glycidyl ether of 1,1,1-trimethylolpropane or an epoxy-novolak.

12. A copolymer according to claim 9, wherein 0.1 to 1 mol of diphosphite is employed per epoxide equivalent of the epoxy resin.

13. A copolymer according to claim 9, wherein the amounts of the diphosphite and of the epoxy resin are so chosen that a phosphorus-containing epoxy resin containing 2 to 10 %
by weight of phosphorus is formed.

14. A process for the preparation of the copolymers according to claim 1 by heating the reaction mixture at a temperature of 80 to 220°C.

15. A process for the preparation of the dialkyl pentaerythrityl diphosphites of the formula I according to claim 1 by transesterifying a trialkyl phosphite in which the alkyl groups have 1-4 C atoms with pentaerythritol in the presence of a catalyst, which comprises carrying out the transesterification at reflux temperature in toluene or xylene and removing the alkanol formed during the reaction by distillation as an azeotrope with toluene or xylene.

16. A composition of matter containing (a) a phosphorus-containing copolymer according to claim 1 and (b) an epoxy resin.

17. A curable composition of matter containing (a) a phosphorus-containing epoxy resin according to claim 13 and (c) a curing agent for epoxy resins.

18. A crosslinked product obtainable by curing the composition of matter according to claim 16 with a curing agent for epoxy resins,

19. A crosslinked product obtainable by curing the curable composition of matteraccording to claim 17.