GB2120653A - Tertiary amine accelerators for use in unsaturated polyester resin compositions - Google Patents

Abstract

In cold-setting unsaturated polyester resin compositions ion incorporating a copolymerisable vinyl monomer such as styrene and a tertiary amine accelerator, the novel accelerator is one obtained by the reaction of a p-substituted aminobenzene R1-C6H4-NH2, where R1 is C1-C6 alkyl group, an aryl group, -OH or -OCH3, with a glycidyl compound <IMAGE> where R4 is a group containing carbon, hydrogen, and optionally oxygen. The compositions can be formulated as stoppers for car body repairs.

Description

SPECIFICATION Unsaturated polyester resin compositions This invention relates to unsaturated polyester resin compositions, and in particular to unsaturated polyester resin compositions which set in the cold on admixture with a free-radical initiator catalyst, such as an organic peroxide.

Polyester resin compositions of the above kind are based on (a) an unsaturated polyester derived from a glycol component, for example propylene glycol, and a dicarboxylic acid component which includes one having ethylenic unsaturation, usually an a0-unsaturated acid, such as maleic acid (b) a vinyl monomer copolymerisable with the unsaturated polyester, for example styrene or methyl methacrylate, and (c) a tertiary amine accelerator. Immediately before use the composition is mixed thoroughly with a free-radical-liberating catalyst (usually an organic peroxide) for the copolymerisation of (a) with (b).The catalyst-for example a diacyl peroxide such as dibenzoyl peroxide-enables copolymerisation of the unsaturated polyester with the vinyl monomer to proceed at a much lower temperature than it otherwise wouid. The function of ingredient (c), the tertiary amine accelerator, is to reduce still further-namely to ambient temperature (250C or below)-the temperature at which copolymerisation can proceed, or to accelerate copolymerisation if in fact it proceeds at ambient temperature. Such compositions are known as 'cold setting', and when admixed with the free-radical initiator they set hard well within an hour.

A number of tertiary amine accelerators are known (see for example GB-A-952 302, 1129 861, 1 276 232 and 1 567 677), and among the most widely used of them are p-substituted aminobenzenes, e.g. p-toluidine, in which the hydrogen atoms of the -NH2 group are replaced by a group containing a p-hydroxy substituent; for example, N,N'-bis-(P-hydroxyethyl)-p-toluidine. These may be used in the form of a polyester e.g. a polyester obtained by reacting the hydroxyethyl compound with adipic or phthalic acid.

We have now found that teritary amines obtained by the reaction of a p-substituted aminobenzene

(Formula I) where R1 is a C1-C6 alkyl group, an aryl group, --OH or -OCH3 with a glycidyl compound of the formula

(Formula II) where R4 is a group containing carbon and hydrogen, and optionally oxygen (for example as part of the group -CO-), are useful accelerators in cold-setting unsaturated polyester compositions.

As will appear later, a glycidyl compound having two epoxy groups, for example

may be used in conjunction with a glycidyl compound having only one.

The amount of tertiary amine accelerator employed in cold-setting compositions as defined forms at least 0.01% by weight of the unsaturated polyester plus vinyl monomer, and preferably 0.110% by weight thereof. A particularly preferred range is 0.56% by weight. The tertiary amines are particularly useful in the formulation of cold-setting compositions which incorporate a filler, whether fibrous such as cellulose or glass fibre, or non-fibrous such as talc, barium sulphate or silica, such as are employed in the repair of metal, wood or stone structures, and specially in the repair of car bodies.

In the glycidyl compound of formula II;

R4 may be

where R5 is preferably H, but may be C1-C4 alkyl group; (2) a C1-C6 alkyl or cycloaliphatic group; (3) CH2=CH-CH2-;

where R6 is -H or -CH3; (5) R7-CO- where R7 is a C1-C10 alkyl or aryl group.

The glycidyl compound is preferably employed in a molar proportion 2-2.2 moles:1 mole of psubstituted aminobenzene. The product of its reaction with the aminobenzene has the formula Ill;

The tertiary amines of the above structure may be reacted with the unsaturated polyester resin, before the latter is mixed with styrene or other vinyl monomer, to produce an 'internally accelerated' resin. They may also be converted into a saturated polyester (in the sense that the polyester has no ethylenic unsaturation) by condensation with for example 0.5-0.83 moles of a dibasic acid of formula IV, such as adipic or phthalic acid or anhydride: HO. CO. R8. CO. OH IV where R8 is a C2-C8 alkylene group, a cycloalkylene group or an arylene group.The structure of a typical polyester of this kind has formula V:

the average value of y being from 1 to 5.

A di-epoxy glycidol compound used along with the monoepoxy compound for the preparation of the tertiary amine may have the structure VI:

where R2 is:

(3) a C2-C6 straight or branched chain diva lent aliphatic hydrocarbon group (4) -OC. . R3. CO-where R3 is a C2-C6 alkylene, cycloaliphatic or arylene group.

When a di-epoxy glycidyl compound is employed along with a mono-epoxy glycidyl compound, it is preferably employed in molar proportions such that the aminobenzene:diepoxy:monoepoxy=x:(x-1 ):2-2.2, where x will ordinarily be 2-10. The structure of the tertiary amine product will be VII:

The preparation of suitable tertiary amine accelerators will now be described.

A. Preparation from p-toluidine and phenyl glycidyl ether A.1 Reaction without solvent 50.8 grms. (0.474 moles) of p-toluidine were added to a 250 ml glass reaction vessel equipped with a nitrogen inlet tube, thermometer, stainless steel agitator, reflux condenser and dropping funnel.

A steady stream of nitrogen was passed through the apparatus and the reactor contents were heated to 1 600C. The heat was then turned down and 149.5 grms. (0.995 moles) of phenyl glycidyl ether was added via the dropping funnel over a period of 35 minutes at such a rate that the exothermic reaction maintained the temperature of the reactor contents at 1 600--1 700C. After the addition of the phenyl glycidyl ether had been completed the reactor contents were maintained at 1600--1700C for a further 60 minutes. The sticky, amber-coloured product obtained was cooled and poured out. It slowly crystallised over a period 7-10 days.

A.2 Reaction in the presence of solvent 53.6 grms. of p-toluidine (0.5 moles) and 93 grms. of isopropanol were put into a 500 ml glass reaction vessel equipped as in A.1. A steady stream of nitrogen was passed through the apparatus. The reactor contents were heated to 480C, whereupon 157.7 grms. (1.05 moles) of phenyl glycidyl ether were slowly added via the dropping funnel. The reactor and its contents were then slowly heated to reflux (90-930C) and were maintained at reflux for 6 hours. The reflux condenser was then replaced by a still head and total water cooled condenser, and the isopropanol was removed by distillation. The product obtained was identical, both in terms of physical characteristics and performance, to the product obtained in A. 1.

B. Preparation from p-toluidine and butyl glycidyl ether This reaction was carried out using 52.6 grms. (0.49 moles) of p-toluidine and 127.8 grms. (0.98 moles) of butyl glycidyl ether, the process being identical to that described in A.1. The product was a reddish-brown viscous liquid.

C. Preparation from p-anisidine and phenyl glycidyl ether This reaction was carried out using 56.2 grms. (0.46 moles) of p-anisidine and 144 grms. (0.96 moles) of phenyl glycidyl ether, the process being identical to that described in A. 1. The product was a dark-brown sticky solid.

Accelerators corresponding to formula Vll D. Preparation from p-toluidine, butanediol 1.4-diglycidyl ether and butyl glycidyl ether 63.3 grms. (0.59 moles) of p-toluidine were placed in a 250 ml glass reaction vessel equipped as described in A. 1. A steady stream of nitrogen was passed through the apparatus and the reactor contents were heated to 1 600 C. The heat was then turned down and 59.7 grms. (0.295 moles) of butanediol 1,4 diglycidyl ether were added over a period of 1 5 minutes at such a rate that the exothermic reaction maintained the temperature of the reactor contents at 1 600--1 700C. 77.0 grms.

(0.59 moles) of butyl glycidyl ether were then slowly added over a 10 minute period. The reactor contents were then maintained at 1600--1700C for a further 60 minutes. The product (a dark reddishbrown viscous liquid) was then cooled and discharged.

E. Preparation from p-toluidine, resorcinol diglycidyl ether and phenyl glycidyl ether The process of D was repeated using 71.3 grms. (0.67 moles) p-toluidine, 111.0 grms. (0.5 moles) of resorcinol diglycidyl ether and 50 g. (0.33 mole) of phenyl glycidyl ether. The product was a hard brittle amber-coloured solid.

Amine accelerators prepared as in A-E above were used in compositions whose unsaturated polyester component was a conventional one, prepared as in F or G below.

F.

2576 grms. (24.3 moles) of diethylene glycol, 586 grms. (9.45 moles) of ethylene glycol, 2664 grms. (18.0 moles) of phthalic anhydride and 1 323 grms. (13.5 moles) of maleic anhydride were condensed together under an atmosphere of nitrogen at temperatures up to 2000C until 481 grms. of water had distilled off. The polyester formed had an acid value of 26.8 mg. KOH per grm.

G.

260.8 grms. (2.46 moles) of diethylene glycol, 65.1 grms. (1.05 moles) of ethylene glycol, 296 grms. (2.0 moles) of phthalic anhydride and 147 grms. (1.5 moles) of maleic anhydride were condensed together under an atmosphere of nitrogen at temperatures up to 2000C until the product had an acid value of 70 mg KOH per grm. of resin.

The invention is further illustrated by the following Examples: Example 1 A polymerisation inhibitor was added to the polyester of F above, and 65 parts by weight of the inhibited polyester were dissolved in 35 parts by weight of styrene. The composition had a viscosity of 2.75 poise (0.275 Pa s) at 250C. The inhibitor used was a 50:50 mixture of 1,4-naphthaquinone and tbutyl hydroquinone, in an amount to give 500 parts of each per 106 parts by weight of the unsaturated polyester/styrene solution.

From this solution, cold-setting pastes were prepared in an entirely conventional way, so as to have a gel time of 5-10 minutes at 200C when catalysed with 1% by weight of benzoyl peroxide. The compositions were based on conventional car body stopping filler (talc) and included a conventional plasticiser polyester resin (British Industrial Plastics Ltd. Resin No. 8134; acid value 12 mg KOH/g; non-volatile content 67% by weight) to improve flexibility and reduce any tendency to crack on exotherm.

Parts by weight Talc 60 * I Polyester/styrene solution 29 Plasticiser polyester resin 9 Thixotropic agent (silica) 1 White pigment 1 100 *Includes various proportions of tertiary amine accelerator (based on total weight of polyester/styrene solution +plasticiser polyester) as follows: Ge/ time at Paste No. Accelerator; weight % 20 oC (mins) 1 Al 1.57 5.75 2 B 0.97 6 3 C 0.75 6.5 4 D 1.2 6.25 5 E 2.02 5.5 The stability of each paste containing tertiary amine accelerator alone (i.e. without admixture with organic peroxide catalyst) was assessed by measuring its gel time at high temperature (650C).

Results were: Paste: 1 2 3 4 5 Days to gel: 19 14 17 16 21 The uncataiysed compositions can accordingly be presumed to have excellent stability on storage at ambient temperature.

Example 2 The tertiary amine accelerator Al described earlier (97.6 g; 0.24 mole) was added to the whole bulk of unsaturated polyester resin obtained according to G above. Addition was at 2000C under nitrogen, and heating was continued until the acid value of the material had fallen from 70 to 27 mg KOH/g. The amine-modified unsaturated polyester thus obtained was cooled and mixed with inhibitor and styrene in the proportions set out in Example 1. The resulting composition had a viscosity of 3.25 poise (0.325 Pa s) at 250C, and contained the equivalent of 7.7% by weight of accelerator Al.

A cold-setting paste was prepared from this composition using the procedure and the proportions of ingredients set out in Example 1, but using amine-modified polyester resin G instead of polyester F.

The properties of the paste were: Gel time at 200C 5.75 mins Days to gel at 650C 25 days Good results as in Examples 1 and 2 were also obtained by using the tertiary amine accelerators with conventional filled pastes catalysed by cyclohexanone peroxide or methyl ethyl ketone peroxide, in conjunction with a conventional cobalt-co-accelerator such as cobalt octoate.

Claims (8)

Claims

1. A cold-setting composition comprising (a) an unsturated polyester resin, (b) a vinyl monomer copolymerisable with the unsaturated polyester resin, and (c) a tertiary amine accelerator, in which the accelerator is one obtained by the reaction of a psubstituted aminobenzene

where R, is a C1-C6 alkyl group, an aryl group, -OH or -OCH3, with a glycidyl compound

where R4 is a group containing carbon and hydrogen and optionally oxygen.

2. A composition according to Claim 1, in which the molar proportion of aminobenzene:glycidyl compound is 1:2-2.2.

3. A composition according to Claim 1 or 2, in which, together with the glycidyl compound defined in Claim 1, a second glycidyl compound

(where R2 has the meaning herein defined) is used in reaction with the p-aminobenzene.

4. A composition according to Claim 3, in which the molar proportions aminobenzene:diepoxy glycidyl:monoepoxy glycidyl compound are: x:(x-1 ):2-2.2, where x has a value in the range 2-10.

5. A composition according to any one of Claims 1 to 4, in which the content of the tertiary amine accelerator is 0.1-1 0% by weight of the unsaturated polyester resin plus copolymerisable vinyl monomer.

6. A composition according to any of Claims 1 to 5, which contains a filler.

7. A composition according to Claim 1 substantially as herein described with reference to Example 1 or 2.

8. The new tertiary amine accelerators defined in Claim 1.