GB2103223A

GB2103223A - Process for stabilising vinyl chloride polymers and copolymers

Info

Publication number: GB2103223A
Application number: GB08219110A
Authority: GB
Inventors: Paul Bourdauducq; Bernard Nolin; Berthe Dujarric
Original assignee: Produits Chimiques Ugine Kuhlmann; Ugine Kuhlmann SA
Current assignee: Produits Chimiques Ugine Kuhlmann; Pechiney SA
Priority date: 1981-07-17
Filing date: 1982-07-02
Publication date: 1983-02-16
Also published as: ES8308579A1; ES514095A0; FR2509740A1; IT8267916A1; GB2103223B; BE893840A; IT1156475B; IT8267916A0; FR2509740B1

Abstract

A process for the stabilisation of a polymer or copolymer of vinyl chloride, which process comprises incorporating a tertiary phosphite of isotridecyl alcohol in the polymer or copolymer, in an amount of from 0.1 to 5% by weight based on the weight of the polymer. The stabilising phosphite is advantageously used in conjunction with Ba-Cd or Ba-Zn soaps. It may also be combined with an epoxide such as epoxidised soya oil and/or an amino additive such as tris- isopropanolamine. The resultant plastics have an excellent long-term stability which is superior to that obtained when other trialkyl or alkylaryl phosphites are used.

Description

SPECIFICATION Process for stabilising vinyl chloride polymers and copolymers The present invention relates to a process for stabilising vinyl chloride polymers and copolymers, particularly plasticised polyvinyl chloride (hereinafter referred to as PVC), wherein a tertiary phosphite of isotridecyl alcohol is used as stabiliser.

It is known that polymers and copolymers of polyvinyl chloride undergo degradation under the effect of heat, iight, oxygen or ozone. To remedy this, stabilisers are used, large numbers of which have been proposed. In particular, it is known to use phosphorous esters in conjunction with organic metal salts, the best known combinations being barium-cadmium laurate and calcium-zinc stearate.

The phosphorous esters generally used are of the following types: (1) triaryl, as described in French Patent 1 1 76 735, wherein the phosphorous ester is a tris nonylphenyl phosphite, (2) alkylaryl, as described in French Patent 1 175 086, where the phosphorous ester is a mixed phosphite of diphenyl and isodecyl (DPDP), and (3) trialkyl.

The phosphorous esters currently used in PVC which is not intended for use with foodstuffs are of the second type, the most common being DPDP. This product has the disadvantage of giving off phenol by partial degradation in the course of conversion.

As substitutes for DPDP it has been proposed to use phosphorous esters of the third type, generally based on a C8 to C18 straight-chained alcohol, such as trilauryl phosphite, for example.

However, these phosphites prove very costly and are less effective than DPDP.

Surprisingly, we have found that by using a tertiary phosphite of isotridecyl alcohol, it is possible to obtain long-term stability of plasticised PVC which is significantly better than that imparted by other trialkyl phosphites and particularly DPDP.

Accordingly, the present invention provides a process for the stabilisation of a polymer or copolymer of vinyl chloride, which process comprises incorporating a tertiary phosphite of isotridecyl alcohol in the polymer or copolymer, in an amount of from 0.1 to 5% by weight based on the weight of the polymer.

The tertiary phosphite of isotridecyl alcohol may, for example, be added to the resin at the compounding stage at the same time as the plasticisers, lubricants, various additives and charges, if any.

The phosphites used in accordance with the invention are added in an amount of from 0.1 to 5% by weight of polymer.

In a preferred embodiment of the invention, the tertiary phosphite of isotridecyl alcohol is used in conjunction with soaps, such as soaps of Ba/Cd and Ba/Zn.

According to the invention, from 0.1 to 1% by weight of polymer, preferably from 0.2 to 0.5% by weight of polymer, of the phosphite are used in the case of a combination with soaps of Ba/Cd, whilst from 0.1 to 5% by weight of polymer, preferably from 2 to 4% by weight of polymer, of the phosphite are used in the case of a combination with soaps of Ba/Zn.

According to the invention, the tertiary phosphite of isotridecyl alcohol may be used in admixture with other phosphorous esters. It may advantageously be combined with an epoxide, such as epoxidised soya oil and/or an amino additive which retards hydrolysis of the phosphite, such as triisopropanolamine.

The tertiary phosphites of isotridecyl alcohol used according to this invention may be prepared by any known process, for example by a reaction of transesterification of an isotridecyl alcohol with a tertiary phosphite of a lighter alcohol or phenyl.

A preferred tertiary phosphite of isotridecyl alcohol is tris isotridecyl phosphite, obtained from an isotridecyl alcohol prepared by the oxo process.

The process according to the invention is particularly appropriate for the stabilisation of plasticised PVC. The term "plasticised PVC" refers to compositions of polyvinyl chloride containing up to 50% of compounds such as phthalates of C8 to C13 alcohols, esters such as sebacates, phosphates, adipates, trimellitates of azelates of straight-chain or branched C4 to C13 alcohols, or liquid chlorinated paraffin, either alone or in admixture.

The process according to the invention produces plastics with excellent long-term stability, far superior to that obtained with the processes currently in use.

The invention will now be illustrated by the following Examples.

In the Examples which follow, the compositions are prepared from a PVC resin suspension, KW 70, with the brand name EKAVYL SK70, made by Produits Chimiques Ugine Kuhlmann; the plasticiser used is 2-diethyl-hexyl phthalate {DOP); the epoxide (if used) is an epoxidised soya oil with the brand name ECEPOX PBI made by Produits Chimiques Ugine Kuhlmann.

The thermal stability of the different mixtures is compared by placing testpieces in a ventilated drying oven at 1 750C.

The testpieces are made from sheets calendered for 5 minutes at 170-1 750C in a two-cylinder mixer. The sheets obtained, 1 mm thick, are cut up into testpieces measuring 5 cm by 2 cm and placed on glass plates which are put into the drying oven at 1 750C. A testpiece is taken out of the oven every 10 minutes, then cut up (to a size of 2 cm by 1 cm), and placed on a card of white paper. The development of coloration (start of yellowing) as a function of time and the fall in stability corresponding to the degradation of the polymer (blackening of the testpiece) are assessed visually.

Example 1 Two identical compositions of plasticised PVC stabilised with soaps of barium and cadmium are mixed with either 0.5% by weight of polymer of DPDP (composition A) or 0.5% by weight of polymer of tris isotridecyl phosphite (composition B). The thermal stability of composition B is greatly superior to that of composition A.

Composition A Composition B

EKAVYL SK70 100 p 100 p DOP 50 50 Ba/Cd soap (BC 12 CIBA GEIGY) 2 2 Stearic acid 0.30 0.30 DPDP 0.50 - Tris-isotridecyl phosphite - 0.50 Time of start of yellowing 1 50 min. 165 min.

Fall in stability (blackening) 195 255 Example 2 Compositions identical to those in Example 1 are prepared, wherein the quantity of tris-isotridecyl phosphite is varied from 0.10 (composition C) to 0.30% by weight of polymer (composition D). The same tests for thermal stability show that only 0.3% by weight of polymer of tris-isotridecyl phosphite are equivalent to 0.5% by weight of polymer of DPDP, whilst the long-term stability is far superior in every case.

Compositions A C D

EKAVYLSK70 100p 100p 100p DOP 50 50 50 BC 12 2 2 2 stearic acid 0.30 0.30 0.30 DPDP 0.50 0 I 0 tris-isotridecyl phosphite 0 0.10 1 0.30 Time of start of yellowing 150 min. 120 min. | 1 50 min.

Fall in stability (blackening) 195 255 l 255 Example 3 The same procedure is used as in Example 2 above, adding epoxidised soya oil to cdmposition C and composition D in an amount of 2% by weight of polymer. In every case, the duration of thermal stability is improved by 1 5 minutes.

Claims

1. A process for the stabilisation of a polymer or copolymer of vinyl chloride, which process comprises incorporating a tertiary phosphite of isotridecyl alcohol in the polymer or copolymer, in an amount of from 0.1 to 5% by weight based on the weight of the polymer.

2. A process according to Claim 1, wherein the phosphite is the tris-isotridecyl phosphite obtained from an isotridecyl alcohol prepared by the oxo process.

3. A process according to Claim 1 or 2, wherein the tertiary phosphite of isotridecyl alcohol is used in an amount of from 0.1 to 1% by weight, based on the weight of the polymer, in conjunction with a soap of barium and cadmium.

4. A process according to Claim 1 or 2, wherein the tertiary phosphite of isotridecyl alcohol is used in an amount of from 0.1 to 5% by weight, based on the weight of the polymer, in conjunction with a soap of barium and zinc.

5. A process according to any one of the preceding claims, wherein an epoxide is also incorporated in the polymer.

6. A process according to any one of the preceding claims, wherein an amino additive which retards hydrolysis of the phosphite is also incorporated in the polymer.

7. A process for the stabilisation of a polymer or copolymer of vinyl chloride substantially as described in any one of the foregoing Examples.

8. A plastics material comprising a polymerised or copolymerised vinyl chloride stabilised by a process as claimed in any one of the preceding claims.