GB1571105A

GB1571105A - Plasticised unsaturated polyester resin composition

Info

Publication number: GB1571105A
Application number: GB22952/76A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1976-06-03
Filing date: 1976-06-03
Publication date: 1980-07-09
Also published as: ZA773209B; BE855169A

Description

(54) PLASTICISED UNSATURATED POLYESTER RESIN COMPOSITION (71) We, IMPERIAL CHEMICAL INDUSTRIES LIMITED, Imperial Chemical House, Millbank, London SW1P 3JF, a British Company do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a resin composition, in particular to an unsaturated polyester resin composition.

It is known to formulate unsaturated polyester resin compositions from an unsaturated polyester, an ethylenically unsaturated monomer copolymerisable therewith and a saturated polyester plasticiser whereby a casting or moulding composition is obtained which cures with a minimum of shrinkage. The unsaturated polyesters which are used in such compositions may be derived from an unsaturated dibasic acid such as maleic acid, a saturated polyol such as propylene glycol and, optionally, a saturated dibasic acid such as adipic acid or isophthalic acid. We have now found that when such unsaturated polyester resin compositions contain an unsaturated polyester which has been derived from terephthalic acid a product is obtained which has particular value as a sheet moulding composition.

According to the invention rherefore an unsaturated polyester resin composition comprises an ethylenically unsaturated polyester, an ethylenically unsaturated monomer copolymerisable therewith and a plasticiser, the ethylenically unsaturated polyester being derived in part from terephthalic acid and the plasticiser comprising a liquid saturated polyester derived from adipic acid and a dihydric alcohol.

The ethylenically unsaturated polyester is derived from a polybasic acid and a polyol.

The polybasic acid component comprises an ethylenically unsaturated polybasic acid, suitably containing up to 20 carbon atoms, e.g.

maleic acid, fumaric acid, mesaconic acid, citraconic acid or itaconic acid; and terephthalic acid. The polybasic acid may optionally but less preferably include as well as trephthalic acid one or more other dibasic adds which are not ethylenically unsaturated and which suitably contain up to 20 carbon atoms, e.g. adipic, glutaric or succinic acid. The molar ratio of terephthalic acid to the unsaturated dibasic acid in the polybasic acid component of the unsaturated polyester is suitably in the range 1 : 10 to 3 : 1, preferably 1: 5, to 1 : 1 and is more preferably 1 : 2 or 1: 3.

The polyhydric alcohol component of the unsaturated polyester preferably contains up to 20 carbon atoms. It may be a glycol, e.g.

mono-, di-, or tri-ethylene glycol, mon, di-, or tri-propylene glycol, mono, di- or tributylene glycol, neopentyl glycol or hexane diol. The polyhydric alcohol may contain more than two hydroxy groups, e.g. glycerol or pentaerythritol but generally a glycol, particularly propylene glycol, is preferred.

The ethylenically unsaturated monomer which is copolymerisable with the ethylenically unsaturated polyester can be chosen from those compounds used for this purpose. Thus the monomer may be a vinyl-substituted aromatic or heterocyclic compound, e.g. styrene, alpha- methylstyrene, alphachlorostyrene, vinyltoluene, meta- or para- 1,4divinyl benzene or vinylpyrrolidone. The monomer may also be an ethylenicaily unsaturated ester, e.g. vinyl acetate, allyl acetate, diallylmaleate, diallylphthalate, triallyleyanuxate or a lower (C1 to C) allyl ester of acrylic or methacrylic acid. Alternative monomers which may be used include acrylonitrile or methacrylonitrile. The preferred copolymerisable monomer is styrene, the unsatrated polyester being generally soluble in this hydrocarbon.

The plasticiser which is used in the composition comprises a liquid saturated polyester, i.e. the reaction product of a polybasic acid and polyhydric alcohol and with a molecular weight preferably in the range 500 to 15,000 more preferably 500 to 7,000. The polybasic acid is adipic and the polyhydric alcohol dihydric so that the resulting polyester is linear rather than cross-linked, so producing the desired liquid rather than solid polyester. The dihydric alcohols which form the polyester may have up to 20 carbon atoms, aliphatic alcohols being preferred. Examples of suitable alcohols include mono-, di-, and triethylene glycol, mono-, di- and tri- propylene glycol, mono, di- and tri- batylene glycol, neopentyl glycol and hexane diol. Preferably the plasticiser is polypropylene adipate the polyester derived from propylene glycol and adipic acid. In some instances it is advantageous to use another plasticiser as well as the saturated polyester as the combination may be synergistic and have an unexpectedly beneficial effect on the properties of the unsaturated polyester resin composition and articles made therefrom.

The additioned plasticiser which may be used in the composition as well as the saturated polyester lis suitably polymeric in nature and may be a low molecular weight (preferably less than 1,000) hydrocarbon, for example, a low molecular weight wax, preferably one containing 10 to 50 carbon atoms.

Alternatively a low molecular weight hydrocarbon substituted by one or more functional groups e.g. halogen, carboxyl, hydroxyl, amine or amide groups may be used. Examples of these substituted hydrocarbons include chlorinated hydrocarbon polymers, C, to C,0 carboxylic (particularly alkanoic) acids, alcohols, amines and amides such as stearic acid and stearyl alcohol. In particular, a low molecular weight hydrocarbon or substituted low molecular weight hydrocarbon such as stearic acid may be combined witil polypropy Lene adipate.

The unsaturated polyester resin composition may contain 40 to 80% by weight of the ethylenically unsaturated polyester 20 to 50% by weight ethylenically unsatrated comonomer and 2 to 30% by weight plasticiser.

Sheet moulding compositions may be formed from the novel unsaturated polyester resin compositions described above by incorporating fillers and a glass or similar fibre and by extruding through rollers in sheet form. Suitable fillers include chalk, silica, day, slate and talc. The composition may also include other additives commonly used in unsaturated polyester resin compositions, e.g. pigments, lubricants, e.g. calcium stearate, and cure initiators, e.g. perzoompounds such as peroxides and perbentoates.

A typical sheet moulding composition contains 100 parts unsaturated polyester and Co- polymerisable monomer, 5 to 30 parts plasticiser, 50 to 150 parts filler and 25 to 75 parts of glass, other additives totalling up to 20 parts, all parts being by weight. We have found that a sheet moulding composition made in accordance with the invention has an increased percentage elongation as compared with a similar composition without the polyester plasticiser. In addition the finally cured article shows improved corrosion resistance when compared with a similar article made from resin without rhe polyester plasticiser. We have also found that analogous resins containing the polyester plasticiser but replacing the terephthalic acid by conventional isophthalic acid do not show the same improvement in elongation properties or corrosion resistance.

Compositions according to the invention may also be used in "hand-lay-up" techniques in which a reinforcing agent such as glass fibre is coated by hand with an unsaturated polyester resin. The strength and strength retardation of the final produced made by such techniques may be increased up to 40% when a composition according to the invention containing a plasticiser is used as compared with an equivalent composition without the plasticiser.

Compositions according to the invention also have advantages in moulding applications.

Suitably reinforced in the form of a dough or a sheet they may be placed in a mould and squeezed to take the shape of the mould. In this use of the invention a sheet moulding composition need not line the mould but may be folded up and placed in the mould at random the pressure squeezing it into the shape of the mould to give a precisely shaped article of considerable strength.

The invention will now be further described with reference to the following Example.

EXAMPLE 1 An unsaturated polyester was made by esterifying 1 mole of a mixture of maleic anhydride and terephthalic acid with 1.1 mole propylene glycol, the acids being present in a molar ratio of 2: 1 maleic to terephthalic).

The unsaturated polyester was then dissolved in styrene to form a 68 weight % solution and 1.0 weight - methylethylketone peroxide and 0.13 weight % cobalt naphthenate added. Polypropylene adipate alone or with stearic acid was then incorporated in the mixture which was coated on to chopped strand glass mat to form a hand layzup com position (23 weight % % glass) and the strength of the composition was measured using a Tensometer. The strength retention of the composition was also determined by boiling in water for 500 hours and then measuring the strength once more on the Tensometer, the strength retention being the ratio of the strength after boiling to before. The results for three different formulations were as follows:

Strength Strength Retention 400 No additive 540 units = 0.74 540 450 10% by wt. polypropylene 780 units - = 0.58 adipate 780 10% by weight polypropylene 500 adipate + 1% by weight 700 units = 0.71 stearic acid 700 EXAMPLE 2 A composition was made up comprising: an unsaturated polyester* 4.8 kilograms styrene 3.2 kilograms polypropylene adipate 800 grams tertbutyl benzoate 84 grams calcium stearate 80 grams calcium carbonate 8 kilograms stearic acid 80 grams magnesium oxide 160 grams *The unsaturated polyester was made by esterifying 1 mole of a mixture of maleic anhydride and terephthalic acid with 1.1 mole propylene glycol, (the acids being present in a molar ratio of 2:1 maleic to terephthalic).

The percent elongation of this composition was evaluated and compared with that of the composition without the polypropylene adipate. The result of the comparison is shown on the attached graph (curve Y representing the composition according to the invention, curve X the comparative composition) in which it can be seen that the composition according to the invention has the greater percent elongarion showing a region of plasticity before the break point A.

WHAT WE CLAIM IS:- 1. An unsaturated polyester resin composition which comprises an ethylenically unsaturated polyester, an ethylenically unsaturated monomer copolymerisable therewith and a plasticiser, the ethylenically unsaturated polyester being derived in part from terephthalic acid and the plasticiser comprising a liquid saturated polyester derived from adipic acid and a dihydric alcohol.

2. An unsaturated polyester resin composition according to Claim 1 in which the ethylenically unsaturated polyester comprises an ethylenically unsaturated polybasic acid contanning up to 20 carbon atoms.

3. An unsaturated polyester resin composition according to Claim 2 in which the ethylenically unsaturated polybasic acid is maleic acid, fumaric acid, mesaconic acid, citraconic acid or itacomc acid.

4. An unsaturated polyester resin composition according to any one of the preceding claims in which the ethylenically unsaturated polyester also includes a non-ethylenically unsaturated dibasic acid as well as tereph- thalic acid.

5. An unsaturated polyester resin Com position according to Claim 4 in which the nonethylenically unsaturated dibasic acid contains up to 20 carbon atoms.

6. An unsaturated polyester resin composition according to Claim 5 in which the non-ethylenically unsaturated dibasic acid is adipic, glutaric or succinic acid.

7. An unsaturated polyester resin composition according to any one of claims 2 to 6 in which the molar ratio of terephthalic acid to the unsaturated polybasic acid is in the range 1 : 10 to 3 : 1.

8. An unsaturated polyester resin come position according to Claim 7 in which the ratio is in the range 1 : 5 to 1 : 1.

9. An unsaturated polyester resin com position according to Claim 8 in which the ratio is 1 : 2 or 1 : 3.

10. An unsaturated polyester resin com position according to any one of the preceding claims in which the ethylenically unsaturated polyester comprises a polyhydric alcohol con taining up to 20 carbon atoms.

11. An unsaturated polyester resin comF position according to Claim 10 in which the polyhydric alcohol is mono-, di- or tri-ethylene glycol, mono-, di-, or tri- propylene glycol, mono-, di or tri- butylene glycol, neonpentyl glycol, hexane diol, glycerol or pentaeryrhritol.

12. An unsaturated polyester resin com position according to any one of the preceding claims in which rhe ethylenically unsaturated monomer is a vinylzsubstituted aromatic or heterocyclic compound an ethylenically un saturated ester, acrylonitrile or methacrylonit rile.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Strength Strength Retention 400 No additive 540 units = 0.74 540 450 10% by wt. polypropylene 780 units - = 0.58 adipate 780 10% by weight polypropylene 500 adipate + 1% by weight 700 units = 0.71 stearic acid 700 EXAMPLE 2 A composition was made up comprising: an unsaturated polyester* 4.8 kilograms styrene 3.2 kilograms polypropylene adipate 800 grams tertbutyl benzoate 84 grams calcium stearate 80 grams calcium carbonate 8 kilograms stearic acid 80 grams magnesium oxide 160 grams *The unsaturated polyester was made by esterifying 1 mole of a mixture of maleic anhydride and terephthalic acid with 1.1 mole propylene glycol, (the acids being present in a molar ratio of 2:1 maleic to terephthalic). The percent elongation of this composition was evaluated and compared with that of the composition without the polypropylene adipate. The result of the comparison is shown on the attached graph (curve Y representing the composition according to the invention, curve X the comparative composition) in which it can be seen that the composition according to the invention has the greater percent elongarion showing a region of plasticity before the break point A. WHAT WE CLAIM IS:-

1. An unsaturated polyester resin composition which comprises an ethylenically unsaturated polyester, an ethylenically unsaturated monomer copolymerisable therewith and a plasticiser, the ethylenically unsaturated polyester being derived in part from terephthalic acid and the plasticiser comprising a liquid saturated polyester derived from adipic acid and a dihydric alcohol.

13. An unsaturated polyester resin com

position according to Claim 12 in which the monomer is styrene, alpha-methylstyrene, alpha-chlorostyrene, vinyltoluene, meta- or para- 1,4-divinylbenzene, N-vinyl pyrrolidone, vinyl acetate, allyl acetate, diallylmaleate, diallylphthalate, triallylcyanurate or a Cl to C,; alkyl ester of acrylic or methacrylic acid.

14. An unsaturated polyester resin com position according to any one of the preceding claims in which the liquid saturated polyester has a molecular weight in the range 500 to 7,000.

15. An unsaturated polyester resin com position according to Claim 14 in which the saturated polyester is formed from an aliphatic dihydric alcohol containing up to 20 carbon atoms.

16. An unsaturated polyester resin com position according to Claim 15 in which the dihydric alcohol is mono-, di- or tri-ethylene glycol, mono-, di- or tri-propylene glycol, mono- di- or tri-butylene glycol, neopentyl glycol or hexane diol.

17. An unsaturated polyester resin com position according to Claim 16 in which the plasticiser is polypropylene adipate.

18. An unsaturated polyester resin com position according to any one of the preceding Claims in which the plasticiser also comprises a low molecular weight hydrocarbon.

19. An unsaturated polyester resin com position according to Claim 18 in which the plasticiser also comprises a wax containing 10 to 50 carbon atoms.

20. An unsaturated polyester resin com position according to Claim 18 in which the plasticiser also comprises a low molecular weight hydrocarbon substituted by one or more functional groups.

21. An unsaturated polyester resin com position according to Claim 20 in which the functional group is halogen, carboxyl, hydroxyl, amine or amide.

22. An unsaturated polyester resin composition according to Claim 21 in which the plasticiser also comprises a chlorinated hydrocarbon polymer or a C10 to C30 carboxylic acid, alcohol, amine or amide.

23. An unsaturated polyester resin composition according to Claim 22 in which the plasticiser is stearic acid.

24. An unsaturated polyester resin composition according to any one of the preceding claims which contains 40 to 80% by weight of ethylenically unsaturated polyester, 20 to 50% by weight ethylenically unsaturated monomer and 2 to 30% by weight plasticiser.

25. A sheet moulding composition which comprises an unsaturated polyester resin composition according to any one of the preceding claims together with a filler and glass fibres.

26. A sheet moulding composition according to Claim 25 in which the filler is chalk, silica, clay, slate or talc.

27. A sheet moulding composition according to Claim 25 or Claim 26 which comprises 100 parts by weight unsaturated polyester and unsaturated monomer, 5 to 30 parts by weight plasticiser, 50 to 150 parts by weight filler, 25 to 75 parts by weight glass and up to 20 parts by weight other additives.

28. An unsaturated polyester resin composition according to Claim 1 substantially as described in Example 1.

29. An unsaturated polyester resin composition according to Claim 1 substantially as described in Example 2.

30. An article whenever made from an unsaturated polyester resin composition according to any one of the preceding claims.