GB2090264A - Polymerisation process - Google Patents

Abstract

A solution polymerisation process for the preparation of a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 and comprising cross- linked particles which are capable of forming a sol in the reaction solvent, which process comprises: (i) polymerising one or more monomers, the or at least one of which is a cross-linking agent, in a solvent which (a) has a solubility parameter from 2.5 cal<1/2>ml<-3/2> below to 1.0 cal<1/2>ml<-3/2> above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material; (ii) monitoring the polymerisation until polymeric material as herein defined is obtained; and (ii) terminating the polymerisation before gelation is observed. r

Description

SPECIFICATION Polymerisation process This invention relates to polymeric materials; more particularly this invention relates to polymeric materials comprising cross-linked particles which are capable of forming sols; to processes for their preparation; and to compositions comprising them.

According to one aspect of this invention, there is provided a solution polymerisation process for the preparation of a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 and comprising cross-linked particles which are capable of forming a sol in the reaction solvent, which process comprises: (i) polymerising one or more monomers, the or at least one of which is a cross-linking agent, in a solvent which (a) has a solubility parameter from 2.5 cal+ml-312 below to 1.0 cal+ml-312 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material; (ii) monitoring the polymerisation until a polymeric material as herein defined is obtained; and (iii) terminating the polymerisation before gelation is obtained.

The solution polymerisation process of the invention may be an addition, for example a cationic, anionic or free radical, polymerisation or a condensation polymerisation.

A class of addition polymerisation to which the present invention may advantageously be applied is cationic addition polymerisation to which the following types of monomer, inter alia, are susceptible: (a) cyclic and linear mono- and poly-vinyl (thio)ethers, including furfural and furfuryl alcohol; (b) other compounds comprising at least one 3- or 4- membered oxa- or thia- substituted ring, for example mono- and poly-epoxides and lactones with a 4-membered ring; (c) cyclic aliphatic anhydrides, for example maleic anhydrides; (d) aliphatic aldehydes; and (e) mono- and poly-vinyl aromatic hydrocarbons, such as styrene, alkyl styrenes, such as vinyl toluene, divinyl benzene and indene.

Mixtures of such monomers may be used.

In accordance with a preferred aspect of this invention the, or one of the, monomers comprises a polymerisable cyclic (thio)ether. By "(thio)ether" is meant herein an ether or a thioether. Suitable polymerisable cyclic (thio)ethers have the formula:

in which: R,,R2 and R4, which may be the same or different, each represent a hydrogen atom or a substituted or unsubstituted hydrocarbyl or hydrocarbyloxy group; R3 represents a substituted or unsubstituted methylene, ethylene or 1 3-propylene group; R5 represents a monovalent polymerisable group; Q represents an oxygen or a sulphur atom; and X represents:

in which: Y represents an oxygen atom or a -NR6-group wherein R6 represents any of the values which R may assume; a is O or 1; b is O or 1; c is 1 or 2; disOor1; with the proviso that at least one of b or d is 1.

The groups R1, R2 and R4 may each represent a substituted or unsubstituted hydrocarbyl or hydrocarbyloxy group; examples include unsubstituted or halo-substituted C1 to C4 alkyl, such as methyl or ethyl; unsubstituted or halo-substituted C6 to C10 aryl or aralkyl, such as phenyl or benzyl; and oxy analogues. In the case of R4, increase in the size of the group increases the steric hindrance to the hydrolysable ester or amide function X and thereby increases the stability of the polymer. It is preferred, however, from the standpoint of ease of preparation and availability, that at least one, and preferably all, of R1 R2 and R4 represents a hydrogen atom. The group R3 may represent a mono- or poly- substituted ethylene group, preferably an unsubstituted ethylene group; that is, a dihydro(thia)pyran derivative.

Preferred such compounds are ethers; that is, those compounds of the above formula wherein Q represents an oxygen atom, especially dihydropyrans.

X may, as shown, represent any hydrolysable carboxylic acid ester, carbonate ester or oxalate ester function, or an amide analogue. Preferably, however, X represents -COO- or -CH2OCO-.

Particularly preferred polymerisable cyclic ethers have the formula:

R5 may suitably represent any group which can participate in cationic polymerisation; for example those derivable from monomers (a) to (e) mentioned hereinbefore. Preferred examples are vinyl (thio)ether and epoxy groups.

It is particularly preferred that R5 represents a cyclic vinyl (thio)ether, especially of the formula:

in which: R11, R2,, R3' and R4', which may be the same or different, represent any of the values which R1, R2, R3 and R4 may assume; M represents the group -zx'-; Q' represents an oxygen or sulphur atom; X' represents any of the values which X may assume; and Z represents a single bond or a substituted or unsubstituted hydrocarbylene.

Especially preferred polymerisable cyclic ethers are the reaction products formed by subjecting one or a mixture of dihydropyran aldehydes to disproportionation by the Tischenko reaction; they have the formula:

in which: R1', R2' and R4,, which may be the same or different, represent any of the values which R1, R2 and R4 respectively may assume. A preferred such compound is acrolein tetramer (in which the R1 all represent hydrogen atoms).

Polymerisable cyclic ethers wherein X comprises a -COO- or -CH20CO- group may conveniently be prepared from the tetramer of the corresponding unsaturated aldehyde produced by the Tischenko reaction; namely:

Thus, cyclic ethers wherein X comprises a -COO- group may be prepared by reaction of the tetramer with an alcohol R5OH using a transesterification catalyst and reaction conditions:

Cyclic ethers wherein X comprises a -CH2OCO- group may be prepared by reaction of the tetramer with a lower alkyl carboxylic acid ester RsCOOR7 in which R7 represents a lower alkyl group using a transesterification catalyst and reaction conditions::

The respective by-products may also be transesterified with RsCOOR7 or R50 H to give, correspondingly:

The corresponding amides may be prepared analogously.

Cyclic ethers where X comprises a -COO- group may also be obtained by mild oxidation of the dimer of the corresponding unsaturated aldehyde, followed by esterification of the salt, for example the silver salt.

Meta-carbonates and oxalates may be obtained, respectively, by esterification and transesterification:

It is, however, to be stressed that acrolein tetramer is readily prepared from acrolein which is a commercially available material; can readily be purified; and has been found to be satisfactory in the practice of this invention.

Other specific examples of polymerisable cyclic ethers include bis-(3,4-dihydropyran-2-ylmethyl) succinate, bis-(3,4-dihydropyran-2-ylmethyl) o-terephthalate, bis-(3,4-dihydropyran-2-yl) adipate, bis (3,4-dihydropyran-2-yimethyl) adipate,

wherein: n represents a number of at least one; and R8 is a polyvalent organic bridging group which desirably does not contain a basic group since these can interfere with the acid catalysis required, as will be explained later, for the polymerisation.

A further class of addition polymerisation to which the present invention may also advantageously be applied is free radical addition polymerisation. Suitably the, or one of the, monomers comprises a vinyl- or vinylidene group-containing monomer, preferably a substituted or unsubstituted (meth)acrylate ester, especially a C1 to C8 alkyl methacrylate. Specific examples of such monomers include methylacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, n-hexyl methacrylate, ethyl hexyl methacrylate, lauryl methacrylate, phenyl acrylate, isodecyl methacrylate, 2-ethoxyethyl methacrylate, 2-n-butoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, 2-phenoxyethyl acrylate and 2-phenoxyethyl methacrylate. Such monomers require the presence of a bis- or tris-vinyl or vinylidene group-containing monomer as cross-linking agent. This may be a hydrocarbon, for example an unsubstituted or hydrocarbyloxylated aromatic hydrocarbon such as divinyl benzene. Preferably, however, the crosslinking agent comprises a bis- or tris- vinyl or vinylidene group-containing ester, particularly preferred examples being the bis-methacrylate ester of polyethylene glycol, the bis-methacrylate ester of ethylene glycol or triallyl cyanurate.

Cationically polymerisable monomers in classes (b) and (e) above may also be free radical polymerised. Of these, epoxides and episulphides are particularly versatile, being also susceptible to anionic addition polymerisation, for example with organometallic initiators. Suitable monoepoxides include the alkylene oxides such as ethylene oxide, propylene oxide and butylene oxides; the aromatic oxides such as styrene oxide. Polyepoxides include many commercially available (cyclo)aliphatic and aromatic polyepoxides such as:

Analogous mono- and polyepisulphides may also be used, especially ethylene and propylene sulphides.

There are many classes of condensation polymerisation to which the present invention is applicable; for example, condensation polymerisations for the production of polyamides, polyesters, polycarbonates, phenol-formaldehydes, urea-formaldehydes, urea-melamines and polyurethanes, particularly the latter. In the preparation of polyurethanes according to the invention one of the monomers comprises a polyisocyanate, for example a diisocyanate such as a (cyclo)aliphatic, araliphatic or aromatic diisocyanate. Specific examples include 2,4, and 2,6 toluene diisocyanate; (cyclo)aliphatic diisocyanates such as 1 ,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, and cyclohexylene 1,2- and 1 ,4-diisocyanate; and araliphatic diisocyanates such as 4,4'-diphenylmethane diisocyanate.

A versatile group of cross-linking agents, particularly for polyurethanes and also for cationically polymerisable species, such as the cyclic (thio)ethers, are monomers comprising at least three groups containing a reactive hydrogen atom such as a hydroxy, carboxy, amino or mercapto group (amino not being preferred for cationic polymerisation), for example those comprising at least three groups which are hydroxyl, and/or carboxyl groups.

Examples include polycarboxylic acids, polyhydric phenols, hydroxy acids and polyhydric alcohols, desirably those with less than 18, preferably less than 10, carbon atoms; for example aliphatic polyols such as glycerol, erythritol, pentaerythritol, sorbitol, dulcitol, inositol, 2-ethyl-2-hydroxy-methylpropane1 ,3-diol and 1 2,6-hexanetriol; aromatic polyols such as 1 ,2,3-trihydroxybenzene, 1,2,4trihydroxybenzene, 1 ,3,5-trihydroxybenzene; araliphatic polyols; hydroxy aliphatic, alicyclic and aromatic carboxylic acids, including Krebs cycle acids, such as citric acid, malic acid, tartaric acid, 2hydroxy-3-methyl (D) succinic acid, ascorbic acid, 2,3-dihydroxybenzoic acid, 2,4,-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3,4-trihydroxybenzoic acid, 2,4,5trihydroxybenzoic acid, 2,4,6-trihydroxybenzoic acid and 3,4,5-trihydroxybenzoic acid. Mixtures of polycarboxylic acids, polyhydric phenols, hydroxy acids and polyhydric alcohols may be used. Preferably the polycarboxylic acids, polyhydric phenols, hydroxy acids and polyhydric alcohols are linear.

Monomers comprising two groups containing reactive hydrogen atoms as aforesaid, for example di-carboxy or hydroxy substituted monomers may be utilised, especially as comonomers with cyclic(thio) ethers, epoxides or polyisocyanates, for example to produce polymers of the type disclosed in U.K. 1,572,598 and U.S. 4,221,779.

Examples of di-carboxy or hydroxy monomers include dicarboxylic acids, dihydric phenols, hydroxyacids, glycols and polyesters thereof, desirably those with less than 18, preferably less than 10, carbon atoms; for example oxalic, malonic, succinic, glutaric, and adipic acids, 1,2cyclohexanedicarboxylic, 1 ,3-cyclohexanedicarboxylic and 1 ,4-cyclohexanealcarboxylic acids, phthalic, isophthalic and terephthalic acids, 4,4'-dihydroxyphenyl-2,2-propane, resorcinol, quinol and orsionol, lactic, 2-hydroxylisobutyric, 1 O-hydroxydecanoic, 1 2-hydroxyoctadecenoic, 1 2-hydroxy-cis-9 octadecenoic, 2-hydroxycyclohexane carboxylic, 2-hydroxy-2-phenyl (D) propionic, diphenylhydroxyacetic, 2-hydroxybenzoic, 3-hydroxybenzoic and 4-hydroxybenzoic acids, glycol, propanediols and butanediols.Glycols are most suitable, especially the C2 to C6, preferably C2 to C4 glycols. Mixtures of dicarboxylic acids, dihydric phenols, hydroxy acids and glycols may be used.

Preferably the dicarboxylic acids, dihydric phenols, hydroxy acids and glycols are linear.

Cationic addition polymerisation in accordance with this invention requires acid catalysis. Suitable Bronsted and Lewis acids include strong mineral acids which are not redox reagents under the reaction conditions such as hydrochloric and sulphuric acid, tosylic acid, brosylic acid and the adduct of methanol and boron trifluoride. Suitable Lewis acids include boron trifluoride and its etherate, boron tribromide, aluminium trichloride, aluminium tribromide, gallium trichloride, germanium tetrachloride, tin tetrabromide, zinc chloride and ferric chloride, ferric chloride being preferred. From 0.01% /0 to 2%, particularly from 0.04% to 1%, based on the total weight of the reaction mixture may suitably be used.

In the case of the production of polyurethanes the, or one of the dihydroxy compounds may be a polyethylene oxide, preferably one wherein the ratio of number average weight to functionality Is greater than 1000. The polyurethanes so produced are useful in the performance of the invention disclosed in GB 2047093 and GB 2047094.

It is the nature of the solvent, which may be a mixture of one or more compounds (including latent solvents) the composition of which may be varied, continuously or continually, as the polymerisation proceeds, which is a particularly critical feature of this invention. The solvent may qualitatively be assigned to one of three groups according to its hydrogen bonding capacity: GROUP EXAMPLES strongly hydrogen bonded alcohols, acids, amines, aldehydes moderately hydrogen bonded ketones, esters, ethers, poorly hydrogen bonded hydrocarbons, chlorinated and nitrohydrocarbons, nitriles from which the meaning of "same or adjacent hydrogen bonding group" will be apparent.

The solubility parameter (which is the square root of the cohesive energy density) of a number of solvents is given in Table 1 below. In Table 2 solubility parameter ranges are given for a number of bulk polymers. (Both from "Encyclopaedia of Polymer Science and Technology" published by John Wiley s Sons).

TABLE 1 Solvents Solubility parameter Hydrocarbons aliphatic n-pentane 7.05 isopentane 7.05 n-hexane 7.3 cyclohexane 8.2 n-heptane 7.45 n-octane 7.55 isooctane 6.85 n-nonane 7.65 n-decane 7.75 n-tetradecane 7.95 TABLE 1 (continued) Solvents Solubility parameter butadiene 6.7 isoprene 7.25 aromatic benzene 9.15 toluene * 8.9 o-xylene 9.0 m-xylene 8.8 p-xylene 8.75 ethylbenzene 8.8 naphthalene 9.9 n-propylbenzene 8.65 isopropylbenzene 8.86 mesitylene 8.8 p-cymene 9.85 styrene 8.66 Perfluoro compounds n-perfluorobutane 5.2 n-perfluoropentane 5.5 n-perfluorohexane 5.6 n-perfluoroheptane 5.7 n-perfiuorononane 5.7 perfluorocyclobutane 5.7 perfluorocyclohexane 6.0 perfluorobenzene 8.1 perfluorotoluene 7.7 Halogen compounds aliphatic chlorides dichloromethane 9.7 chloroform 9.3 carbon tetrachloride 8.6 TABLE21 (continued) Solvents Solubility parameter ethyl chloride 8.5 1,1 -dichloroethane 9.1 1,2-dichloroethane 9.8 1,1,1 -trichloroethane 8.5 tetrachloroethane 10.4 isobutyl chloride 8.2 t-butyl chloride 7.9 unsaturated chlorides cis-dichloroethylene 9.7 trans-dichloroethylene 9.2 trichloroethylene 9.2 tetrachloroethylene 9.35 vinyl chloride 8.7 vinylidene chloride 8.6 chloroprene 9.3 aromatic compounds chlorobenzene 9.5 bromobenzene 10.0 iodobenzene 11.3 o-bromotoluene 9.8 aliphatic bromides methyl bromide 9.4 bromoform 10.5 ethyl bromide 8.9 1,2-dibromoethane 10.4 1,1 2,2-tetrabromoethane 10.3 1,2,3-tribromopropane 10.7 aliphatic iodides methyl iodide 9.9 diiodomethane 11.8 ethyl iodide 9.4 TABLE I (continued) Solvents Solubility parameter Hydroxyl compounds water 23.2 phenol 14.5 glycol 15.7 glycerol 16.5 cyclohexanol 11.4 methanol 14.5 ethanol 12.7 n-propanol 11.9 n-butanol 11.4 isobutyl alcohol 10.7 n-amyl alcohol 10,9 n-hexanol 10.7 n-heptanol 10.0 n-octanol 10.3 Acids acetic acid 12.6 n-butyric acid 11.5 isovaleric acid 10.9 n-valeric acid 10.8 Esters methyl formate 10.7 ethyl formate 9.4 methyl acetate 9.6 ethyl acetate 9.1 n-propyl acetate 8.75 isopropyl acetate 8.6 ethyl propionate 8.9 amyl formate 8.65 n-butyl acetate 8.55 TABLE I (continued) Solvents Solubility parameter ethyl n-butyrate 8.15 amyl acetate 8.45 butyl propionate 8.5 ethyl isovalerate 8.65 amyl propionate 8.4 n-butyl n-butyrate 8.0 isobutyl isobutyrate 7.7 isoamyl butyrate 8.5 ethyl benzoate 9.7 diethyl carbonate 8.8 diethyl malonate 10.3 ethylene carbonate 14.5 diethyl phthalate 10.05 vinyl acetate 8.7 methyl acrylate 8.9 ethyl acrylate 8.4 methyl methacrylate 8.7 ethyl methacrylate 8.4 n-butyl acrylate 8.9 n-butyl methacrylate 8.2 isobutyl methacrylate 7.9 Aldehydes benzaldehyde 10.8 acetaldehyde 9.8 n-heptaldehyde 9.7 Ketones acetone 10.0 methyl ethyl ketone 9.3 diethyl ketone 8.8 methyl n-propyl ketone 8.7 TABLE I (continued) Solvents Solubility parameter methyl n-butyl ketone 8.6 methyl amyl ketone 8.5 methyl hexyl ketone 8.45 cyclohexanone 9.9 Ethers diethyl ether 7.4 diisopropyl ether 7.0 P,P'-dichloroethylether 9.8 dioxane 10.0 tetrahydrofuran 9.9 Amines di-n-butylamine 7.85 aniline 10.8 pyridine 10.7 Amides formamide 17.8 acetamide 16.7 dimethylformamide 12.1 dimethylacetamide 11.1 Nitriles acetonitrile 11.9 propionitrile 10.7 n-butyronitrile 10.5 n-valeronitrile 10.1 capronitrile 10.2 malonitrile 15.1 acrylonitrile 10.45 methacrylonitrile 9.1 Nitro compounds nitromethane 12.6 TABLE I (continued) Solvents Solubility parameter nitroethane 11.1 1 -nitropropane 10.2 2-nitropropane 9.9 nitrobenzene 10.0 o-nitrotoluene 10.5 m-nitrotoluene 10.4 Sulfur compounds carbon disulfide 10.0 ethyl mercaptan 8.65 dimethyl sulfide 9.0 diethyl sulfide 8.8 thiophene 9.8 dimethyl sulfone 14.6 diethyl sulfone 12.5 dipropyl sulfone 11.3 dimethyl sulfoxide 13.4 TABLE 2 Solubility Parameter Polymers Manufacturer Poor Moderate Strong Acrylics acrylic solution polymers Acryloid B-44 Rohm # Haas 8.911.9 8.5-13.3 0 Acryloid B-66 Rohm t Haas 8.5-11.1 7.8-12.1 0 Acryloid B-72 Rohm 8 Haas 8.5-12.7 8.9-13.3 0 Acryloid B-82 Rohm # Haas 8.5-11.1 8.9-12.1 0 poly(butyl acrylate) Rohm # Haas 7.0-12.7 7.4-12.1 9.5-12.7 poly(methacrylic acid) Rohm 8 Haas 0 9.9 12.7-14.5 poly(methyl methacrylate) Rohm 8 Haas 8.9-12.7 8.5-13.3 0 poly(ethyl methacrylate) Rohm # Haas 8.5-11.1 7.8-13.3 9.5-11.4 poly(n-butyl methacrylate) Rohm # Haas 7.4-11.1 7.4- 9.9 9.511.4 poly(isobutyl methacrylate) Rohm # Haas 8.5-11.1 8.5- 9.9 9.511.4 Alkyd resins 30% soy, glycerol phthalate 8.5-12.7 8.5-14.7 0 45% soy, glycerol phthalate 7.0-11.1 7.4-10.8 9.5-11.9 45% soy, pentaerythritol phthalate 7.0-11.1 7.4-10.8 9.5-11.9 45% linseed, glycerol phthalate 7.0-11.9 7.4-10.8 9.5-11.9 Epoxy resins bisphenol A-epichlorohydrin condensates Epon E-72 Shell Chemical 8.5-10.6 7.4- 9.9 9.5-11.4 Epon 812 Shell Chemical 8.9-12.7 7.8-14.7 10.0-14.5 Epon 864 Shell Chemical 9.5-12.7 8.5-14.7 0 Epon 1001 Shell Chemical 10.6-11.1 8.513.3 0 Epon 1004 Shell Chemical 0 8.513.3 0 Epon 1007 Shell Chemical 0 8.513.3 0 Epon 1009 Shell Chemical 0 8.5- 9.9 0 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong Hydrocarbon resins cyclized rubber Alpex cyclized rubber Reichhold 7.4-10.6 7.8 0 hydrocarbon resin Gilsonite Brilliant Black American Gilsonite 7.8-10.6 7.8- 8.5 0 Gilsonite Selects American Gilsonite 7.8- 9.5 7.8-8.5 9.5 Nebony 100 Neville Chemical 8.5-10.6 7.8-9.9 0 Neville LX685 Neville Chemical 7.4-10.6 9.3-9.9 0 Panarez 3-210 Amoco Chemical 8.5-10.6 0 0 Petrolatum 12511MP 8.5- 8.9 0 0 natural rubber Pliolite NR Goodyear 8.5-10.6 0 0 Pliolite P-1230 Goodyear 9.5-10.6 0 0 Phenolic resins p-phenylphenol resin Bakelite CKR-5254 Union Carbide 8.5-10.0 7.8-13.3 9.5-10.8 phenolic resin Bakelite CKR-5360 Union Carbide 8.5-11.1 7.8-13.3 9.5-11.4 Bakelite CKR-2400 Union Carbide 8.9-11.9 7.8-13.3 9.5-14.5 Bakelite BKR2620 Union Carbide 0 8.4-14.7 9.5-14.5 terpene-phenol resin Durez 220 Hooker Chemical 8.5-10.6 7.8- 9.8 9.511.4 phenolic resin Durez 550 Hooker Chemical 7.911.9 7.4- 9.8 9.5-14.5 phenol ether resin Methylon 75202 General Electric 0 8.9-12.1 0 Polyesters linear polyester Vitel resin PE100-X Goodyear 11.1 9.9 0 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong poly(ethylene terephthalate) soluble Mylar 49000 Du Pont 10.6-11.1 10.6-11.1 0 soluble Mylar 49001 Du Pont 8.9-10.6 9.3-9.9 0 soluble Mylar 49002 Du Pont 9.5-10.6 9.3- 9.9 0 Amino resins urea-formaldehyde resin Beckamine P-196 Reichhold 9.9-11.1 8.5-10.8 9.5-12.7 butylated urea-formaldehyde resin Beetle 227-8 American Cyanamid O 0 8.911.4 butylated melamine-formaldehyde resin Resunene 888 Monsanto 8.5-10.6 7.4-12.1 9.5-12.7 benzoguanamine-formaldehyde resin Uformite MX-61 Rohm # Haas 8.5-11.1 7.4-11.1 9.5-11.1 Cellulose derivatives cellulose acetate, LL-1 11.1-12.7 9.9-14.7 0 cellulose acetate butyrate 11.1-12.7 8.5-14.7 12.7-14.5 cellulose butyrate, 0.5 sec 11.1-12.7 8.5-14.7 12.7-14.5 cyanoethylcellulose 11.1-12.7 12.2-14.7 0 ethylcellulose, K-200 0 8.5-10.8 9.5-11.4 ethylcellulose, N-22 8.1-11.1 7.4-10.8 9.514.5 ethylcellulose, T-10 8.5- 9.5 7.8- 9.8 9.5- 11.4 cellulose nitrate, RS, 25 cps 11.1-12.7 7.8-14.7 14.5 cellulose nitrate, SS,0.5 sec 11.1-12.7 7.8-14.7 12.7-14.5 Polyamides methylolpolyamide nylon, type 8 Du Pont O 0 11.9-14.5 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong dimer acid-polyamine condensates Versamid 100 General Mills 8.5-10.6 8.5- 8.9 9.5-11.4 Versamid 115 General Mills 8.5-10.6 7.8- 9.9 9.5-12.7 Versamid 900 General Mills O 0 0 Versamid 930 General Mills O 0 9.5-11.4 Versamid 940 General Mills O 0 9.5-11.4 Versalon 1112 General Mills O 0 9.5-11.4 Versalon 1175 General Mills O 0 9.511.4 Rosin derivatives WW gum rosin 8.5-11.1 7.4-10.8 9.511.4 wood rosin M grade 7.4-10.6 7.4-10.8 9.5-14.5 ester gum 7.0-10.6 7.4-10.8 9.5-10.9 Alkydol 160 Reichold 9.5 8.5-10.8 9.5-12.7 rosin-modified phenol-formaldehyde Amberol F-7 Rohm # Haas 8.5-10.6 7.8- 9.8 9.5-10.9 maleic rosin type Amberol 750 Rohm 8 Haas 0 8.9-10.8 9.5-12.7 Amberol S01 Rohm # Haas 8.5-11.1 7.4- 9.9 0 Arochem 455 U.S. Industrial 0 7.8-13.3 9.6-14.5 Chemicals Arochem 462 U.S.Industrial 9.5 8.5-10.8 9.5-14.5 Chemicals polymerized rosin Dymerex Hercules 7.4-10.6 7.8-9.9 9.5-11.4 Nelio B952 Glidden 9.5-10.6 7.4-10.8 9.5-12.7 Nelio VBR757 Glidden 0 8.5-10.8 9.5-14.5 rosin-derived alkyd Neolyn 23 Hercules 8.5-11.1 8.5-13.3 0 a-pinene resin Newport V-40 Tenneco 8.5-11.1 7.4-12.1 9.5-14.5 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong pentaerythrytol ester of rosin Pentalyn A Hercules 8.5-10.6 7.4- 9.9 9.5-11.4 maleic-modified pentaerythrytol ester of rosin Pentalyn G Hercules 8.5-10.6 7.8- 9.9 9.5-10.9 pentaerythrytol ester of dimerized rosin Pentalyn K Hercules 8.5-10.6 7.8- 9.9 9.5 rosin-based polymers Pentalyn 830 Hercules 8.5- 9.5 7.8-10.8 9.5-11.4 Pentalyn 856 Hercules 8.5-11.1 7.4-10.8 9.5-11.4 Vinsol Hercules 10.6-11.9 7.8-13.3 9.5-12.7 Styrene polymers and copolymers butadiene-styrene Buton 100 Enjay 7.4-10.6 7.4- 9.9 0 Buton 300 Enjay 8.5-10.6 7.4- 9.9 9.5-10.5 styrene-maleic anhydride Lytron 810 Monsanto 11.9 9.9-14.7 0 Lytron 820 Monsanto 9.5 8.9-14.7 10.9-14.5 styrene copolymer Marbon 9200 Marbon 8.5-10.6 9.3- 9.9 0 styrene-acrylonitrile-indene terpolymer Piccoflex 120 Penn.Industrial 8.5-11.1 7.8- 9.9 0 modified polystyrenes Styron 440M-27 Dow 8.5-10.6 9.3 0 Styron 475M-27 Dow 8.5-10.6 9.3 0 Styron 480-27 Dow 8.5-10.6 9.3 0 rubber-modified polystyrene Lustrex "High Test 88" Monsanto 8.5-10.6 9.3 0 Shell X-450 Shell Chemical 9.5-10.6 8.5-12.1 9.5-12.7 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong styrene-acrylonitrile copolymer Bakelite RMD4511 (S/An) Union Carbide 10.6-11.1 9.3 0 Vinyl resins poly(vinyl chloride) Exon 470 Firestone 8.5-11.1 7.8- 9.9 0 Exon 471 Firestone 8.5-11.1 7.8-12.1 0 Exon 473 Firestone 8.5-11.1 7.8- 9.9 0 Geon Goodrich 10.6-11.1 9.3- 9.9 0 vinylidene chloride-acrylonitrile poly(vinyl butyl ether) 7.8-10.6 7.4- 9.9 9.5-11.4 poly(vinyl ethyl ether) 7.0-11.1 7.4-10.8 9.5-14.5 poly(vinyl formal) Formvar 7/70E Shawinigan 0 9.9-13.3 0 Formvar 1 5/95E Shawinigan 0 9.913.3 0 poly(vinyl isobutyl ether) 7.0-10.6 7.4- 9.9 9.5-11.4 vinylidene chloride-acrylonitrile copolymers Saran F-120 Dow 9.5-11.1 12.1-14.7 0 Saran F-220 Dow 9.5-11.1 10.8-14.7 0 poly(vinyl acetate) Vinylite AYAA Union Carbide 8.9-12.7 8.5-14.7 14.5 partially hydrolyzed vinyl chloride-vinyl acetate copolymer Vinylite VAGII Union Carbide 10.6-11.1 7.8- 9.9 0 vinyl chloride-vinyl acetate copolymer Vinylite VYIIII Union Carbide 10.6-11.1 7.8-12.1 0 vinyl chloride-vinyl acetate-maleic acid terpolymer Vinylite VMCH Union Carbide 9.3-11.1 7.8-13.3 0 vinyl chloride copolymer Vinylite VXCC Union Carbide 0 8.9-10.8 9.5-14.5 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong vinyl chloride-vinyl acetate copolymer Vinylite VYLF Union Carbide 0 8.9-10.8 9.5-14.5 poly(vinyl butyral) Vinylite XYHL Union Carbide 9.5-11.1 7.8-13.2 0 Vinylite XYSG Union Carbide 9.5-11.1 7.8-13.2 0 poly(ethylene-co-vinyl acetate) Elvax 150 Du Pont 7.8-10.6 0 0 Elvax 250 Du Pont 8.5- 9.5 0 0 Elvax EOD 3602-1 Du Pont 7.8-10.6 7.8- 8.5 0 Miscellaneous synthetic oil Beckolin 27 (modified oil) Reichhold 7.0-11.1 7.4- 9.9 9.511.4 poiy(oxyethylene)glycol Carbowax 4000 Union Carbide 8.9-12.7 8.5-14.7 9.5-14.5 chlorinated rubber 8.5-10.6 7.8-10.8 0 hydrocarbon mixture Conoco H-35 Conoco 7.0-11.1 7.4- 9.9 9.5-11.4 dammar gum (dewaxed) 8.5-10.6 7.8- 9.9 9.5-10.9 chlorosulfonated polyethylene Hypalon 20 Du Pont 8.1- 9.8 8.4- 8.8 0 Hypalon 30 Du Pont 8.5-10.6 7.8- 8.5 0 phosgene-bisphenol A condensate polycarbonate Lexan 100, 105 General Electric 9.5-10.6 9.3- 9.9 0 arylsulfonamide-formaldehyde condensate Santolite MHP Monsanto 10.6-12.7 7.8-14.7 9.5 shellac (pale-pale) 0 9.9-10.8 9.514.5 silicone polymers Silicone DC-23 Dow-Corning 7.4- 8.5 7.4- 7.8 9.5-10.0 Silicone DC-1107 Dow-Corning 7.0- 9.3 9.9-10.8 9.5-11.4 TABLE 2 (continued) Solubility Parameter Polymers Manufacturer Poor Moderate Strong methoxylated partial hydrolyzate of phenyl- and phenylmethylsilanes Sylkyd 50 Dow-Corning 7.0-12.7 7.9-12.9 9.5-14.5 monophenyl polysilaxanol Silicone Intermediate 26018 Dow-Corning 8.5-11.1 7.9-12.2 10.0--1 1.4 soy oil 7.0-11.1 7.4-10.8 9.511.9 soy oil, blown 7.0-11.1 7.4-10.8 9.5-12.7 p-toluenesulfonamide-formaldehyde 11.8 9.914.7 12.7-14.5 In practice, an appropriate solvent for the performance of the present invention may readily be selected by first bulk polymerising the monomer mixture to a solid mass and then determining the swellability of portions of that mass in a number of solvents. Those solvents which swell it in excess of 1 00 pph of polymer will be suitable for the performance of the present invention, provided that they do not contain reactive groups which will interfere with the polymerisation.To obtain high molecular weight cross-linked particles which are capable of forming sols in the solvent, it is desirable to maintain a thermodynamically good solvent at all stages of the reaction.

Specific solvents whose use in the polymerisation of cyclic (thio)ethers and (meth)acrylate esters has been found desirable comprise one or more C, to C4 alkyl acetates, especially methyl acetate and/or ethyl acetate. In the case of the polymerisation of epoxides or episulphides one or more halogenated hydrocarbons such as methylene chloride and'or chloroform were found very suitable. In the case of the polymerisation of polyisocyanates a mixture of one or more sulphoxides with one or more ketones, or chloroform, were found very suitable.

It is an important advantage of this invention that the polymerisation system does not require the presence, as is generally the case with non-aqueous dispersion or aqueous emulsion polymerisations, of an added stabiliser.

The polymerisation in accordance with this invention may be monitored, particularly at laboratory or plant scale, by observing whether an aliquot of the reactant mixture spread onto a glass slide will form a coherent film. Provided that the solvent has been selected in the manner hereinbefore defined, the formation of coherent films occurs well before gelation.

When a coherent film is formed, or when other monitoring suggests, the polymerisation is terminated before gelation. For polymerisations which occur at elevated temperatures this may be achieved by cooling. Alternatively, polymerisation quenching agents may be added: base for cationic addition polymerisation; weak acids for anionic addition polymerisation; and free radical traps such as alkylated phenolic or quinonoid inhibitors for free radical polymerisation.

According to a further aspect, this invention provides a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 and comprising cross-linked particles which are capable of forming a sol whenever prepared by the process herein described. More particularly, this invention provides a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising particles of a homo- or copolymer of a substituted or unsubstituted (meth)acrylate ester cross-linked by a bis- or tris- vinyl or vinylidene group-containing ester which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 caltml-3/2 below to 1.0 calJml-3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material, especially wherein the cross-linking ester comprises the bis-methacrylate ester of polyethylene glycol, the bis-methacrylate ester of ethylene glycol or triallyl cyanurate. This invention also provides a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising cross-linked particles of a homo- or copolymer of a polymerisable cyclic (thio)ether which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 calml-3/2 below to 1.0 cal2 ml~3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material, especially wherein the cyclic (thio)ether comprises acrolein tetramer.This invention further provides a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising cross-linked ,particles of a homo- or copolymer of an epoxide or episuiphide which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 cal m,' l3/2 below to 1.0 cal"ml-3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material.This invention also provides polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising cross-linked particles of a homo- or copolymer of a polyisocyanate which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 cal$mi'2 below to 1.0 carlml-3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material.

By selecting the solvent in accordance with this invention gelation, which in prior art processes rapidly follows the formation of the aforesaid cross-linked, sol-forming particles, is delayed for a sufficient period to enable the termination to be effected in a controlled manner. The sol-forming particles so produced have a very small particle size in the colloidal or sub-colloidal size range; that is an average primary particle size no greater than 0.2 y.

The reacted solutions so formed can either be used as such, in concentrated form, or the polymer can be recovered: Recovery can be effected by solvent evaporation or mixing, either by addition or reverse addition, with an excess of a non-solvent. A particularly desirable feature of the invention is that the polymer produced by addition of excess non-solvent is typically a flowable powder, generally of fine particle size. Moreover, the polymer powder can readily be redissolved in the same or other solvent selected in accordance with this invention.It is believed that the polymer particles are globular when in solution and it is found that they typically contribute little to the viscosity of the solution until their swollen phase volume exceeds a critical fraction of the whole which, in practice, means that the polymer solution can be concentrated to about 20%, and sometimes to about 30%, by weight and still be readily pourable.

The polymer powders of this invention are useful as industrial and pharmaceutical compression moulding materials. They may be used in admixture with an active substance; for example, a pharmaceutical, bacteriostat, viruscide, insecticide, herbicide, larvicide, fungicide, algaecide, nematocide, topical or dermatological agent, antifoulant for marine growth prevention, enzyme, preservative, fluorescent or other pigment. The polymer powders of this invention are particularly useful as pharmaceutical tableting excipients, especially as direct compression tableting excipients. This is particularly the case for polymers prepared from cyclic (thio)ethers, such as acrolein tetramer.The active substance may be incorporated by admixing solid active substance, for example pharmaceutical or pigment, for example before tableting or the active substance may be added to a solution of the polymer, coprecipitated therewith and then tableted. In the latter case the swollen sol particles permit the active substance to penetrate the polymer network. The polymer powders are also useful as additives for bulk rubbers, sound damping formulations, viscosity control additives.

This invention also provides a polymeric material as herein defined which is dissolved in a solvent which is different from the reaction solvent. This solvent may comprise one or more monomers which may be reactive with the polymeric material. Desirably, at least one of the monomers is a (meth)acrylate ester styrene, alkyl styrene, vinyl chloride or acrylonitrile.

This invention also provides a surface coating composition such as an adhesive paint, varnish or lacquer, especially alkyl and acrylic based surface coatings, which comprise a polymeric material, which may comprise pigment introduced as aforesaid, especially one in a solvent which is different from the reaction solvent as aforesaid. This invention further provides a cured such surface coating composition; such materials typically have a reduced drying time, generate less heat and reduce shrinkage. It is to be noted that even if the solvent monomers do not interpolymerise with the polymeric material of this invention they will penetrate the polymer network and their resultant homopolymers will bind the polymer particles by entanglement.

EXAMPLE 1 1.9241 g (0.0086 mols) of acrolein tetramer were added to 0.5379 g (0.0057 mols) of glycerol containing 2% by weight of FeCI3 in a reaction vessel equipped with a nitrogen bleed and a drying tube to exclude moisture. 3.30 cm3 of methyl acetate were added to form a mixture which, initially, was not homogeneous. The mixture was continuously stirred and heated on a water bath whereupon it became homogeneous after about 1 5 minutes and was permitted to reflux.

Aliquots of the reactant mixture spread onto a slide began to produce solid film after 70 minutes from the beginning of reflux. The solution was then neutralised with triethylamine after 73 minutes of reaction, 1.3 x 10-4 mols of triethylamine being required for the neutralisation.

The concentration of polymer in the solution as 8.2% by weight. It was possible to concentrate the polymer solution after neutralisation to about 24% by weight by distilling the excess methyl acetate or by using a rotary evaporator.

Polymer powder was obtained from the solution either by a film spreading technique or by precipitating the polymer solution by gradual addition to an excess of hexane.

EXAMPLE 2 1.9876 g (0.0089 mol) of acrolein tetramer were added to 1.0703 g (0.012 mols) of glycerol containing 2% by weight of FeCI3, in a reaction vessel equipped as in Example 1. 4 cm3 of methyl acetate were added to form a mixture which became homogeneous after about 1 5 minutes of stirring and heating. The mixture was refluxed for one hour then a further amount (1.91889 g; 0.0086 mols) of acrolein tetramer was added, along with 56 mol of methylene chloride so that the ratio methyl acetate:methylene chloride was approximately 7:93 by volume and the ratio acrolein tetramer:glycerol was 3:2. The refluxing was continued and after 90 minutes from commencing refluxing a film began to form when the solution was spread on a glass slide. The mixture was neutralised after 100 minutes by adding triethylamine.

The concentration of polymer in the solution was 8.3% by weight. The polymer solution could be concentrated to about 24% by weight either by distillation or using a rotary evaporator.

Polymer powder was obtained as described in Example 1.

Using essentially the same preparative technique, copolymers with acrolein tetramer:glycerol weight ratios 70:30, 72:28, 74:26 and 76:24 were also prepared. These copolymers usually had lower molecular weights than the 3:2 copolymer produced in this and Example 1 above.

EXAMPLE 3 The preparation was carried out in two stages: (a) Master batch preparation: A master batch of citric acid and acrolein tetramer in ethyl acetate was prepared for use in the preparation of citric acid acrolein tetramer copolymer. The ratio acrolein tetramer:citric acid in the master batch was stoichiometric (2 mols of acrolein tetramer to 1 mol of citric acid on the assumption that the three carboxylic groups and one hydroxyl group in citric acid would react). 35.0965 g (0.1567 mols) of acrolein tetramer were added to 1 5.0506 g citric acid (0.0783 mols), and the mixture was then added to 450 cm3 of ethyl acetate.

The mixture was next placed in a round-bottom flask and refluxed with continuous stirring under a nitrogen bleed. The refluxing and stirring was stopped after half an hour to provide a homogeneous prepolymer which formed only a low molecular weight tacky film. The notional concentration of acrolein tetramer and citric acid was 10% w/v.

(b) Preparation of the copolymer: 200 cm3 of methylene chloride were added to 100 cm3 of the master batch together with 10 cm3 of 0.3% FeCI3 solution in methylene chloride. The contents were then stirred at room temperature. After 30 minutes the mixture became cloudy and a solid film-producing solution was formed. The reaction was then terminated by adding triethylamine after one hour of stirring in both stages (a) and (b) combined. Soon after the addition of triethylamine the mixture became very cloudy.

The polymer concentration was 3.5% w/v and could be concentrated to about 10% w/v using a rotary evaporator.

Polymer powder was obtained by precipitation by gradually adding the solution to an excess of hexane.

EXAMPLE 4 Copolymers of acrolein tetramer/citric acid/glycerol of different ratios were prepared.

(a) The following procedure was used for the preparation of copolymers with weight ratios of 78:11:11, 78:9:13, 78:7:15 and 78:2:20 of acrolein tetramer/citric acid/glycerol. A similar procedure could be used for other ratios.

1.17 g of acrolein tetramer were added to 0.5 g of anhydrous citric acid and 0.5 g glycerol containing 2% by weight of FeCI3 in a reaction vessel equipped with a nitrogen bleed and a drying tube to exclude moisture. 20 cm3 of ethyl acetate were added to form a mixture which, initially, was not homogeneous. The mixture was continuously stirred and heated on a water bath whereupon it become homogeneous after about half an hour and was permitted to reflux. After one hour of refluxing a further 2.38 g of acrolein tetramer were added together with 30 cm3 methylene chloride. The ratio of acrolein tetramer to the other components was thus 78%. After 30 minutes refluxing after the second addition, the solution was film-forming. The solution was then neutrnlised by adding a few drops of triethylamine.

The concentration of the polymer in the solution was 9% w/v. Polymer powder was obtained by precipitation by adding excess hexane.

(b) Copolymers of acrolein tetramer/citric acid/glycerol with ratios of 78:13:9, 78:1 5:7 and 78:20:2 were prepared by using the following procedure.

1.00 g of acrolein tetramer was added to 0.41 glycerol containing 2% by weight FeCI3 and 0.59 g of anhydrous citric acid in a reaction vessel equipped with a nitrogen bleed and a drying tube to exclude moisture. 50 cm3 ethyl acetate were added to form a mixture which, initially, was not homogeneous.

The mixture was continuously stirred and heated on a water bath whereupon it became homogeneous after about 10 minutes and was permitted to reflux. After 25 minutes of refluxing a further 2.55 g of acrolein tetramer were added, along with 25 cm3 methylene chloride and 0.4 cm3 0.3% ferric chloride solution in methylene chloride. The ratio of acrolein tetramer to the other components was thus 78% of the total content of acrolein tetramer/citric acid/glycerol. After 10 minutes refluxing after the second addition the mixture was film-forming. The solution was then neutralised with triethylamine.

Polymer powder was obtained by precipitation by adding excess hexane. By using the above procedure, copolymers of acrolein tetramer/citric acid/glycerol with a higher content of citric acid than glycerol were prepared, provided that the necessary additional amount of ferric chloride was added in the second stage.

EXAMPLE 5 2.24 g of acrolein tetramer (0.01 mol) and 10.0 cm3 of a 0.1% FeCI3 solution in methyl acetate were mixed in a reaction vessel. The concentration of acrolein tetramer in the solution was 22 wt.%. The mixture was then allowed to react at a temperature of 200C and after 65 minutes a turbid solution was formed. After 70 minutes 1.14 cm3 (0.02 mol) of ethanoi was added to terminate the polymerisation.

After the addition of the alcohol, the mixture was refluxed for a further 1 5 minutes to produce a slightly turbid low viscosity solution. The solution, spread on a glass microscope slide, produced a continuous solid dry polymeric film.

Polymer powder was obtained by adding excess alcohol or hexane to the solution.

EXAMPLES 6 TO 8 The materials used in these three Examples were: (a) a cycloaliphatic epoxy resin (Trade Mark CY1 79, 3M Company); (b) epoxy curing agent FC503 (Trade Mark, 3M Company); (c) the polymer, in solution in methyl acetate, produced according to Example 5.

The three components were admixed, in the proportions by weight given in the Table below, and the methyl acetate was evaporated off in the dark in an oven with forced ventilation. The resulting materials were golden yellow in colour.

TABLE 3 Example No. 6 7 8 FC503 10 10 10 Microparticulate polymer 20 30 40 CY179 70 60 50 100 100 100 The products were coated as thin films on an aluminium sheet and were found to cure rapidly to a tack-free, scratch-resistant film after one passage under a U.V. lamp in a line travelling at 300 feet per minute.

EXAMPLE 9 Diglycidylether of bisphenol known as Epikote (Trade Mark) 828 was used to prepare a crosslinked sol in methylene chloride solution.

5 cm3 of BF3solution was added to a mixture of 100 cm3 30% Epikote 828 solution and 750 cm3 of methylene chloride. Polymerisation was effected at room temperature under a nitrogen atmosphere for 3 hours, during which time the solution become more viscous. The mixture was film-forming after 20 minutes and was neutralised, with triethylamine, after 3 hours of polymerisation.

Various polymers based on Epikote 828 were prepared using the above procedure but altering the polymerisation time from 1 hour to 5 hours. The BF3 solution was prepared by diluting BF3 methanol solution to a 45% solution with methylene chloride. The Epikote 828 solution was prepared in methylene chloride.

At the end of the polymerisation, the polymer concentration was 6.5% w/v. However, it was possible to concentrate the solution by using a rotary evaporator while avoiding heating. It was possible to achieve 16% polymer solution without affecting its stability. Polymer powder was obtained by precipitation by adding excess hexane, slowly with continuous stirring. The polymer powder could be readily dispersed again in methylene chloride.

EXAMPLE 10 Polyethyiene glycol 6000 (ex ICI) and trimethylol propane were dried under vacuum for 1 hour at 700 C. Diphenylmethane-4,4'-diisocyanate (MDI) was distilled under reduced pressure and used immediately.

Polyethylene glycol 6000 (10 g) was placed in a 250 cm3 glass flask equipped with stirrer, nitrogen bleed, condenser and CaCl2drying tube to exclude moisture with a mixture of dimethylsulphoxide and methyl ethyl ketone in a weight ratio of 1:1 (50 g) and heated to 70"C. MDI (1.15 g) was then added followed, after 5 minutes, by trimethylol propane (0.27 g). The mixture was next heated at 80-1 000C for 5 hours by which time no infra-red isocyanate absorption band at 2275 nm could be detected and polymer solution had formed.

Polymer powder was obtained by slowly adding the polymer solution to an excess of cyclohexane or petrol ether (60/80) followed by filtration and drying in a vacuum oven at room temperature.

The powder so formed would readily redisperse to a stable system in either 1:1 dimethylsulphoxide/methyl isobutyl ketone or into water.

The dispersion in water had the interesting characteristic of being clear at room temperature but of milky appearance at 1000C. The dispersion is useful as a thickener in water as it can provide very viscous dispersions at room temperature which show a remarkable reduction in viscosity at elevated temperature.

EXAMPLE 11 3.89 g of triallyl cyanurate was added to 105 cm3 of methyl methacrylate in a round bottom flask heated in a heating mantle. These were stirred together with 5.00 cm3 ethyl acetate under a nitrogen atmosphere for 20 minutes followed by the addition of 5 ml of 7% benzoyl peroxide solution. Refluxing and stirring was continued under a nitrogen atmosphere for 5 hours. After 5 hours polymerisation the mixture was cooled to room temperature. Polymer powder was obtained by precipitation by adding the polymer solution gradually to excess methanol.

The molar ratio methyl methacrylate:triallyl cyanurate was 64:1. The polymer solution concentration was 20%.

Using the above procedure, other molar ratios of copolymers were prepared from 5:1 to 1:4.

EXAMPLE 12 A mixture of 21.26 cm3 methyl methacrylate, 41.56 cm3 ethyl hexacrylate and 15.08 polyethylene glycol 600 dimethacrylate in 600 cm3 ethyl acetate was allowed to stand under a nitrogen atmosphere for 20 minutes. 2 cm3 of 7% benzoyl peroxide solution were then added. Refluxing and stirring were next carried out in a round bottom flask in a heating mantle under a nitrogen atmosphere for 5 hours.

After 5 hours copolymerisation, the solution was cooled to room temperature. The copolymer formed from this mixture at this stage was rubbery. The molar ratio methyl methacrylate:2-ethyl hexyl acrylate:polyethylene glycol 600 dimethacrylate was 2:2:1. The concentration of the solution was about 10% w/v. It was possible to concentrate the solution to about 25% w/v by evaporation of the solvent.

Other copolymers with different molar ratios of components could be prepared by using the above procedure, although catalyst and solvent concentration may need to be altered, e.g. copolymer of molar ratio methyl methacrylate:2-ethylhexyl acrylate:polyethylene glycol 600 dimethyacrylate of 2:2:2 was prepared using 1 cm3 of 7% benzoyl peroxide solution. The polymer solution concentration was about 7% w/v. This extra amount of solvent was necessary to avoid gelation during the process.

EXAMPLE 13 Benzoyl peroxide was added to a solution of methyl methacrylate and triallyl cyanurate (mol ratio 64:1) in ethyl acetate and the reaction mixture was refluxed under a nitrogen atmosphere with stirring for 5 hours. The concentration of the polymer solution was 20% by weight. The polymer solution was added slowly, with continuous stirring, to methanol to precipitate the polymer which was filtered and dried to give a powders EXAMPLE 14 Example 13 was repeated using a ratio of 20:1. At the end of the 5 hour period the polymer was recovered by precipitation in methanol, filtration and drying.

EXAMPLE 1 5 Benzoyl peroxide was added to a solution of methyl methacrylate, 2-ethyl hexylacrylate and polyethylene glycol 600 dimethylacrylate (mol ratio 2:2:1,) in ethyl acetate and the reaction mixture was stirred continuously under reflux in a nitrogen atmosphere for 5 hours to give a polymer solution.

The total polymer concentration in the ethyl acetate was 10% by weight.

EXAMPLE 16 1.3310 g of triallyl cyanurate (ex BDH, used without further purification) and 6.85 g of methyl methacrylate (molar ratio 1:12, respectively) were mixed with 81.8 cm3 of ethyl acetate (ex Fisons, dried over MgS04 and distilled before use) in a round bottom flask equipped with a nitrogen bleed and a drying tube to exclude moisture. The solution so formed was purged with oxygen-free nitrogen for 20 minutes. The solution was then heated and stirred with a mantle cum stirrer. When reflux commenced 5.0 cm3 of a 7% by weight solution of benzoyl peroxide, as catalyst, in ethyl acetate were added.

Heating was discontinued after 32 hours of refluxing when a polymer film was observed to form in the flask. The polymer was precipitated as a fine white powder by addition of excess diethyl ether to the solution. 82% conversion was obtained.

EXAMPLE 17 2.8770 g of triallyl cyanurate and 23.11 g of methyl methacrylate (molar ratio 1 :20, respectively) were mixed with 280 cm3 of ethyl acetate (initial monomer concentration 10% w/v), and reacted essentially as described in Example 1 6. After 343 hours of refluxing a slight haze, but no polymer film, was observed in the flask. Heating was discontinued and the polymer precipitated as described in Example 16. 51% conversion was obtained.

EXAMPLE 18 3.6267 g of triallyl cyanurate and 46.61 3 g of methyl methacrylate (molar ratio 1 :64, respectively) were mixed with 525 cm3 of ethyl acetate in a three-necked, round bottom flask equipped with a condenser, drying tube, nitrogen bleed and a self-sealing rubber septum. The solution so formed was purged with oxygen-free nitrogen for 20 minutes. The solution was then heated and stirred with a -mantle cum stirrer. When reflux commenced, 5.0 cm3 of a 7% by weight solution of benzoyl peroxide, as catalyst, in ethyl acetate were added.While the reactant mixture was polymerising its polymer content was estimated, at about every 30 minutes, by syringing out 1.0 cm3 aliquots of reactant mixture; accurately weighing them; adding them to a clean, dry preweighed aluminium dish; and evaporating to dryness by heating in an oven at 1000C for 30 minutes. The percentage conversion was then estimated from a set of three such measurements.

After 52 hours another 5.0 cm3 shot of catalyst was added and polymer content was continually measured, as aforesaid, until the solids content after evaporating to dryness remained unaltered in two consecutive determinations. At this time the reaction had been in progress for 132 hours. Thereafter a final 5.0 cm3 shot of catalyst was added and reflux maintained for a total reaction time of 142 hours, by which time a conversion of 98.8% was estimated.

Petroleum ether (ex Koch-Light b.p. 80-1 000C) was next added dropwise to the stirred reacted mixture until it became hazy. This hazy solution was then added dropwise to a large excess of petroleum ether which was maintained vigorously stirred. The polymer precipitated as a fine white powder which was filtered and dried overnight in vacuo.

EXAMPLE 19 2.0257 g of the polymer prepared in Example 18 were placed in a clean quickfit test tube to which 6.692 g of methyl acrylate (ex BDH, distilled under vacuum) were added. The tube was then securely stoppered and shaken for 10 minutes after which 0.005 g of benzil (ex Fisons Scientific Apparatus Ltd., recrystallised from absolute alcohol), as initiator, was added. Shaking was next continued for a further 3 minutes whereafter the mixture was allowed to stand for a further 5 minutes to give a 23.2% w/w solution of the polymer.

Aliquots were then polymerised to form a film of 3 thou thickness between two clear glass plates sealed by a rubber gasket by placing in U.V. radiation for 12 hours.

EXAMPLE 20 2.3760 g of the polymer prepared in Example 18 were dissolved in 7.488 g of methyl methacrylate (ex BDH, distilled under vacuum) containing 0.0063 g of azobisisobutyronitrile (ex Eastman Chemicals Limited, recrystallised from absolute alcohol) as initiator. The clear solution so formed was polymerised for 6 hours in the manner described in Example 1 9.

A very clear film with a smooth surface was formed which was brittle on scratch but resistant, up to 40 passes, to the solvent action of an acetone-damped cloth.

EXAMPLE 21 In essentially the same procedure as Example 20, 3.3530 g of the polymer of Example 18 were dissolved in 6.552 g of methyl methacrylate and polymerised using 0.007 g of benzil as initiator EXAMPLE 22 3.8660 g of the polymer prepared in Example 18 were dispersed in 6.468 g of ethyl acrylate (ex BDH, distilled under vacuum) in a test tube to which 0.0502 g of azobisisobutyronitrile was added. The tube was then shaken for 5 minutes forming a 37.4% w/w solution of the polymer which was photopolymerised for 5 hours in the manner described in Example 19.

EXAMPLE 23 6.0 g of the polymer prepared in Example 1 8 were dispersed, in stages, in 4.62 g of ethyl acrylate in a test tube to which 0.014 g of benzil was added. The tube was then vigorously shaken until a clear solution (which was viscous but still pourable) was obtained. The tube was next treated with sonic energy to remove air bubbles entrapped during shaking and the solution was photopolymerised for 1 6 hours in the manner described in Example 19.

Claims (36)

1. A solution polymerisation process for the preparation of a polymeric material having a weight average molecular weight from 5,000 to 20,000,000 and comprising cross-linked particles which are capable of forming a sol in the reaction solvent, which process comprises: (i) polymerising one or more monomers, the or at least one of which is a cross-linking agent, in a solvent which (a) has a solubility parameter from 2.5 calml-3/2 below to 1.0 caltml-3 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material; (ii) monitoring the polymerisation until polymeric material as herein defined is obtained; and (iii) terminating the polymerisation before gelation is obtained.

2. A process according to Claim 1 wherein the polymerisation is an addition polymerisation.

3. A process according to Claim 2 wherein the polymerisation is a cationic addition polymerisation.

4. A process according to Claim 3 wherein the, or one of the, monomers comprises a polymerisable cyclic (thio)ether.

5. A process according to Claim 4 where the cyclic (thio)ethel comprises acrolein tetramer.

6. A process according to Claim 2 wherein the polymerisation is a free radical addition polymerisation.

7. A process according to Claim 6 wherein the, or one of the, monomers comprises a vinyl or vinylidene group-containing monomer.

8. A process according to Claim 7 wherein the vinyl or vinylidene group-containing monomer comprises a substituted or unsubstituted (meth)acrylate ester.

9. A process according to Claim 8 wherein the substituted or unsubstituted (meth)acrylate ester comprises a C1 to C8 alkyl methacrylate.

10. A process according to any of Claims 6 to 9 wherein a bis- or tris- vinyl or vinylidene groupcontaining monomer is present as cross-linking agent.

11. A process according to Claim 1 0 wherein the cross-linking agent comprises a bis- or tris- vinyl or vinylidene group-containing ester.

12. A process according to Claim 11 wherein the ester comprises the bis-methacrylate ester of polyethylene glycol, the bis-methacrysate ester of ethylene glycol or triallyl cyanurate.

13. A process according to any of Claims 2 to 5 wherein the, or one of the, monomers comprises an epoxide or episuiphide.

14. A process according to Claim 1 wherein the polymerisation is a condensation polymerisation.

1 5. A process according to Claim 14 wherein the, or one of the, monomers comprises a polyisocyanate.

16. A process according to any of Claims 2 to 5, 13, 14 or 1 5 wherein a monomer comprising at least three groups which are hydroxyl and/or carboxyl groups is present as cross-linking agent.

1 7. A process according to any of Claims 4, 5 and 8 to 12 wherein the solvent comprises one or more C, toC4 alkyl acetates.

1 8. A process according to Claim 1 3 wherein the solvent comprises one or more halogenated hydrocarbons.

19. A process according to Claim 15 wherein the solvent comprises a mixture of one or more sulphoxides with one or more ketones.

20. A polymeric material having a weight average molecular weight from 5,000 to 20,000,000 and comprising cross-linked particles which are capable of forming in sol whenever prepared by the process of any of Claims 1 to 19.

21. A polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising particles of a homo- or copolymer of a substituted or unsubstituted (meth)acrylate ester cross-linked by a bis- or tris- vinyl or vinylidene group-containing ester which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 calfml-3/2 below to 1.0 cal2ml-3'2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material.

22. A polymeric material according to Claim 21 wherein the cross-linking ester comprises the bismethacrylate ester of polyethylene glycol, the bis-methacrylate ester of ethylene glycol or triallyl cyanurate.

23. A polymeric material having a weigh; average molecular weight from 5,000 to 20,000,000 comprising cross-linked particles of a homo- or copolymer of a polymerisable cyclic (thio)ether which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 carmI-3'2 below to 1.0 cal;rml-3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material.

24. A polymeric material according to Claim 23 wherein the cyclic (thio)ether comprises acrolein tetramer.

25. A polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising cross-linked particles of a homo- or copolymer of an epoxide or episulphide which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 cal)ml-3/2 below to 1.0 caliml-3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material.

26. A polymeric material having a weight average molecular weight from 5,000 to 20,000,000 comprising cross-linked particles of a homo- or copolymer of a polyisocyanate which are capable of forming a sol in a solvent which (a) has a solubility parameter from 2.5 calTml312 below to 1.0 caltiml~3/2 above the solubility parameter of the bulk polymeric material and (b) is of the same or adjacent hydrogen bonding group as the bulk polymeric material.

27. A polymeric material according to any of Claims 23 to 26 wherein a monomer comprising at least three groups which are hydroxyl and/or carboxyl groups is present as cross-linking agent.

28. A polymeric material according to any of Claims 20 to 27 which is a flowable powder.

29. A compression moulding material according to Claim 28.

30. A moulding material according to Claim 29 which is a pharmaceutical tableting excipient.

31. A pharmaceutical tableting excipient according to Claim 30 which is a direct compression excipient.

32. A polymeric material according to any of Claims 20 to 27 which is dissolved in a solvent which is different from the reaction solvent.

33. A polymeric material according to Claim 32 wherein the solvent is one or more monomers reactive with polymeric material.

34. A polymeric material according to Claim 33 wherein at least one of the monomers is a (meth)acrylate ester.

35. A surface coating composition which comprises a polymeric material according to any of Claims 32 to 34.

36. A cured polymeric material according to any of Claims 32 to 35.