GB2076409A - Novel stabiliser mixture - Google Patents

Abstract

Stabiliser mixture of a) 95 to 80 per cent by weight of an organotin compound of the formula R<1>Sn(SCH2COOR<3>)3, wherein R<1> is methyl, n-butyl or n-octyl, and R<3> is C12-C14-alkyl, and b) 5 to 20 per cent by weight of a mercapto acid ester of the formula [HS(CH2)xCOO]yR<2>, wherein x is 1 or 2, y is 1 or 2, and R<2> is C1-22-alkyl when y is 1, or is C1-22-alkylene when y is 2, for stabilising chlorine-containing thermoplasts. e

Description

SPECIFICATION Novel stabiliser mixture The invention relates to a novel stabiliser mixture of an organotin stabiliser and a mercapto acid ester, which stabilising mixture is particularly suitable for stabilising synthetic organic polymers, especially homo- or copolymers of vinyl chloride. The invention relates also to the material stabilised in this manner.

It is known from the German Auslegeschrift (Publication after Examination) No. 1,217,609 that for the stabilisation of vinyl chloride polymers it is possible to use a mixture of a mercapto acid ester, for example trimethylnonylmercaptoacetate (col. 1, lines 36/37), and an organotin or antimony compound - each known to be a stabiliser, the organotin compounds mentioned being for example dimethyltin oxide, dibutyltin oxide, and the like (col. 2, line 28). By using the organotin compound together with the mercapto acid esters, there is obtained a stabilising action equal to that resulting from the use of much greater amounts of the expensive organotin compound on its own.

The above extremely general statement provides no precise guidance in practice, since it has been shown that a mixture of the said type does not provide by any means in all cases the favourable result anticipated, especially since the specific mixtures given in the said German 'Auslegeschrift' do not always yield satisfactory results on application.

It has therefore been the object of the present invention to provide a stabiliser mixture which does not have the disadvantage of the known mixtures - or does not have them to the same extent, and which for practical use is excellently suitable for stabilising in particular vinyl chloride polymers.

Organotin stabilisers suitable for the purpose are the C12-C14 esters of the German 'Auslegeschrift' No.

2,501,331, the combination of which with mercapto acid esters produces a stabiliser mixture of which the excellent properties have greatly exceeded all expectations. Free mercaptans impair in general the PVC's initial colour attainable with organotin mercaptides. The mixture according to the invention does not have this disadvantage, so that an increase of long-term stability becomes for the first time technically feasible.

The invention accordingly relates to a stabiliser mixture of a) 95 to 80 per cent by weight of a monoorganotin compound of the formula R1Sn(SCH2COOR3)3, wherein R1 is methyl, n-butyl or n-octyl, and R3 is C12-Cl4-alkyl, and b) 5 to 20 per cent by weight of a mercapto acid ester of the formula [HS(CH2)xCOO]vR2, wherein xis 1 or 2, y is 1 or 2, and R2 is C1.22-alkyl when y is 1, or is C1.22-alkylene when y is 2.

R3 is preferably C14-alkyl, or is a mixture of alkyl groups which have 12-14C atoms with a majority of C14-alkyl groups.

R2 as C122 alkyl is any such alkyl group, the same alkyl group as in the alcohol moiety of the organotin ester being preferably used, that is, -C14H29, or mixtures of alkyl groups containing mainly -C14H29 with proportions of for example -C12H25, straight-chain alkyl being preferred.

As C122-alkylene, R2 is any such alkylene group, branched-chain or preferably straight-chain, and preferably having 1 to 14 C atoms, such as methylene, ethylene, butylene or tetramethylene.

In a preferred embodiment, up to 30 per cent by weight of component a) can be replaced by the corresponding diorganotin compound of the formula R21Sn(SCH2COOR3)2.

There are preferably used 95 to 85 per cent by weight of component a) and 5 to 15 per cent by weight of component b).

The components are known from the German 'Auslegeschrift' mentioned in the foregoing. Should any of them still be new, they can be produced by processes analogous to known processes. The mixtures according to the invention can be produced in a manner known per se by mixing; or instead the monoalkyltin-trismercapto acid esters of component a) are produced with a corresponding excess of mercapto acid esters of component b). Finally, it is also possible to mix together the components in the polymer, or directly before addition to the polymer.

The stabiliser mixture according to the invention is very suitable for providing protection against degradation caused by the action of heat in thermoplasts containing chlorine. It can be incorporated into the thermoplasts to be stabilised, in the customary devices, before processing, the respective amounts incorporated being 0.05-5.0 per cent by weight, preferably 0.1 - 1.5 per cent by weight, relative to the total weight of the composition.

Chlorine-containing thermoplasts which may be mentioned are: polyvinylidene chloride and preferably polymers formed from or based on vinyl chloride. Those preferred are suspension polymers and polymers produced by bulk polymerisation, and also emulsion polymers washed free from emulsifiers. In the case of polyvinyl chloride, it can be PVC containing plasticisers, or hard PVC.

Comonomers for thermoplasts based on vinyl chloride which may be mentioned are: vinylidene chloride, transdichloroethane, ethylene, propylene, butylene, maleic acid, acrylic acid, fumaric acid or itaconic acid.

Depending on the purpose of application, there can be added to the moulding compound, before, during or after addition of the stabiliser mixture, further additives. As further additives, together with which the stabiliser mixture according to the invention can be used, there are mentioned for example: antioxidants, such as 2,6-dialkyiphenols, derivatives of alkylated hydroquinones, hydroxylated thiodiphenyl ethers, alkylidene-bis-phenols, 0-, N- and S-benzyl compounds, hydroxybenzylated malonic esters, hydroxybenzyl aromatic substances, 2-triazine compounds, amides of P-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid, esters of P-(3,5-di-tert-butyl-4-hyd roxyphenyl)-propion ic acid, esters of ,-(5-tert-butyl-4-hydroxy-3- methylphenyl)-propionic acid, esters of 3,5-di-tert-butyl-4-hydroxyphenylacetic acid, acylaminophenols, benzyl-phosphonates, aminoaryl derivatives, UV absorbers and light stabilisers, such as 2-(2'hydroxyphenyl )-benzotriazoles, 2,4-bis-(2'-hydroxyphenyl)-6-al kyl-s-triazines, 2-hydroxy-benzophenones, 1,3-bis-(2'-hydroxybenzoyl)-benzenes, esters of unsubstituted or substituted benzoic acids, acrylates, also nickel compounds, sterically hindered amines, oxalic acid diamides, metal deactivators, phosphites, peroxide-decomposing compounds, polyamide stabilisers, basic co-stabilisers, nucleating agents, or other additives, for example plasticisers, lubricants, emulsifiers, fillers, carbon black, asbestos, kaolin, talcum, glass fibres, pigments, optical brighteners, fire-proofing agents, and so forth.

Examples of further additives, together with which the stabiliser mixture according to the invention can be used, are given in the German Offenlegungsschrift No.2,427,853, pp. 18to 24.

Preferred costabilisers are epoxides, for example epoxidised soya bean oil, of which up to 10% by weight can be additionally contained in the stabiliser mixture.

A preferred composition of the stabiliser mixture according to the invention is for example, relative to the total mixture: a) 67 per cent by weight of C4HgSn(SCH2COOR3)3, b) 18 per cent by weight of (C4Hg)Sn(SCH2COOR3)2, c) 10 per cent by weight of HSCH2COOR3, and d) 5 per cent by weight of epoxidised soya bean oil, wherein R3 is a mixture of alkyl groups which contain 12-14 C atoms, the majority being C14-alkyl groups.

The following Examples serve to further illustrate the invention. 'Parts' are parts by weight and percentages are per cent by weight.

Examples 1-3 Recipe: S-PVC (K value 60; Formolon S 60) 100 parts, lubricant Loxiol G 74 0.5 part, lubricant Loxiol G 16 0.7 part, Kureha BTA Ill (modifier) 5.0 parts, Kane PA 20 (processing auxiliary) 1.0 part, and stabiliser 1.2 parts.

Example 1 (comparison: priorart) Monobutyltin-trismyristylthioglycolate serves as the stabiliser.

Example 2 (comparison: prior art) A mixture of 90% of monobutyltin-trismyrstylthioglycolate and 10% of epoxidised soya bean oil.

Example 3 (according to the invention) The stabiliser comprises 90% of monobutyltin-tris-myristylthioglycolate and 10% of thioglycolic acid myristyl ester.

The following Table contains discoloration values (Yellowness index) measured during a prolonged rolling test at 1900.

Table time 5' 10' 15' 20' 25' 30' 35' 40' Example 1: 3.9 5.3 7.9 13.3 24.2 41.1 56.2 73.9 Example 2: 4.3 5.9 8.6 16.3 34.1 60.2 75.7 92.5 Example 3: 3.3 4.6 6.3 9.2 14.1 25.1 40.9 64.5

Claims (11)

1. A stabiliser mixture of a) 95 to 80 per cent by weight of a monoorganotin compound of the formula R1Sn(SCH2COOR3)3, wherein R1 is methyl, n-butyl or n-octyl, and R3 is C12-Cl4-alkyl, and b) 5 to 20 per cent by weight of a mercapto acid ester of the formula [HS(CH2),COO],R2, wherein xis 1 or 2, y is 1 or 2, and R2 is C1-2ralkyl when y is 1, or is C1 22-alkylene when y is 2.

2. A stabiliser mixture according to Claim 1, wherein in component b) xis 1 or 2, y is 1, and R2 is -C14H2.

3. A stabiliser mixture according to Claim 1 or 2, wherein there are contained 96 to 85 per cent by weight of component a) and 5 to 15 per cent by weight of component b).

4. A stabiliser mixture according to Claim 1, wherein there are contained as component a): 90 per cent by weight of mono-n-butyltin-tris-myristylthioglycolate, and as component b): 10 per cent by weight of thioglycolic acid-myristyl ester.

5. A stabiliser mixture according to Claim 1, wherein there are contained as component a): 90 per cent by weight of mono-n-octyltin-tris-myristylthioglycolic acid myristyl ester, and as component b): 10 per cent by weight of thioglycolic acid-myristyl ester.

6. A stabiliser mixture according to Claim 1, which additionally contains up to 30 per cent by weight of the corresponding diorganotin compound of the formula R21Sn(SCH2COOR3)2.

7. A stabiliser mixture according to any preceding Claim, which mixture additionally contains up to 10 per cent by weight of an epoxide compound.

8. A stabilised composition comprising a chlorine-containing thermoplastic polymer and, as stabiliser, a mixture according to any preceding claim in an amount of 0.05 to 5.0 per cent by weight, relative to the total composition.

9. A stabilised composition according to Claim 8, wherein the chlorine-containing thermoplast is a polymer formed from or based on vinyl chloride.

10. A method of stabilising chlorine-containing thermoplasts, which method comprises the use of a mixture according to Claim 1.

11. A stabilised composition according to Claim 8 substantially as hereinbefore described with reference to Example 3.