Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1996-09-03
1998-04-28
Hoke, Veronica P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524104, 524105, 524111, C08K 545, C08K 53472, C08K 515
Patent
active
057445257
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to stabilised vinyl chloride polymer compositions.
Many articles are made by moulding, extruding and casting homo-polymers and co-polymers of vinyl chloride. These processes involve heating the polymer or co-polymer to temperatures in the order of 180.degree. C. to 200.degree. C. At such temperatures the vinyl chloride polymers and co-polymers undergo considerable degradation, resulting in an adverse colour change. The high temperatures further adversely affect the mechanical properties of the end product.
To overcome such problems, inorganic salts as well as carboxylic acid salts of metals have been added to the PVC. The performance of such materials in retarding the degradation of the polymer is enhanced by the further addition of co-stabilising additives such as organophosphites, epoxidised esters or oils, hindered phenolic antioxidants and polyols.
U.S. Pat. Nos. 2,307,075 and 2,669,548 describe the beneficial effects of adding metal chelates of dicarbonyl compounds to the PVC, whereas GB 1511621 describes the further improvements offered by a stabilising composition comprising divalent metal salts of carboxylic acids together with an organic dicarbonyl compound.
The present invention seeks to provide an alternative stabilisation system.
According to the present invention there is provided a composition based on homopolymers and/or co-polymers of vinyl chloride comprising the following compounds, expressed by weight relative to the weight of polymers/co-polymers: divalent metal salts of a carboxylic acid or phenol; and formula: ##STR1##
in which R.sub.1 represents a linear or branched alkylene or alkenylene radical having up to 20 carbon atoms, an aralkylene radical having from 7 to 20 carbon atoms or an arylene or cycloalkylene radical having from 6 to 20 carbon atoms, the cycloalkylene radicals optionally containing carbon-carbon double bonds; these radicals optionally being unsubstituted or substituted, by one or more halogen atoms or hydroxyl groups or, for aryl or cycloalkylene radicals, by one or more methyl, ethyl or methoxy radicals, the above mentioned radicals optionally also being modified, by the presence in an aliphatic chain of one or more --O--, --CO-- or --CO.sub.2 -- chain members; R.sub.3 and R.sub.4 are defined as R.sub.1 or H and can be the same or different; A is either O, S or NR.sub.7 with R.sub.7 defined as R.sub.1 or H; with the exception that when R.sub.2 =O, A.noteq.O; and R.sub.2 represents O, NR.sub.5 or NNHR.sub.5 wherein R.sub.5 is defined as R.sub.1, H or C(S)NHR.sub.6 wherein R.sub.6 is defined as R.sub.1 or H; or R.sub.2 represents the following: ##STR2##
wherein n is an integer between 1 and 10.
Preferably the composition comprises from 0.001% to 1% of compound A.
Amongst these compounds "A" can be mentioned the following: ##STR3## where n=1, 1.5,2,2.5,3,3.5,4,4.5 or 5.
The best all round performance is obtained with the product N-phenyl-3-acetylpyrrolidine-2,4-dione (Compound B). ##STR4##
Thus relating back to the general formula A; R.sub.1 =alkyl, R.sub.2 =O, R.sub.3 =R.sub.H =H and A=NR.sub.7 where R.sub.7 =phenyl.
Favourable results have also, however, been obtained with the following products: R.sub.7 =methyl, isopropyl, benzyl, p-tolyl and p-methoxyphenyl i.e. where R.sub.7 =alkyl, aralkyl and substituted phenyl respectively; =phenyl; R.sub.7 =phenyl; when R.sub.2 =N-alkyl.
The synthesis of the pyrrolidine compounds named above is described by R. N. Lacey in J.Chem.Soc. 1954, pages 850-854. The synthesis of the tetronic acid derivatives is described in J.Chem.Soc. 1943, pages 241-242 by W. Baker, K. D. Grice and A. B. A. Jansen and of the 3-acetyltetrahydrothiophen-2,4-dione in J.Chem.Soc 1968, pages 1501-1505.
The heat stability of the compounds mentioned above in polyvinyl chloride formulations have been established.
The phrase "compositions based on polyvinyl chloride" used herein should be understood to include compositions comprising any homopolymer of co-polymer of vinyl chloride including chlorinated vinyl chloride polymers a
REFERENCES:
patent: 3306909 (1967-02-01), Uloth
patent: 5093503 (1992-03-01), Meul et al.
Burley Joseph William
Harvey Heather Blue
Schmets Gerard Hub Frans
Akros Chemicals
Hoke Veronica P.
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