Chlorinated thermoplastics stabilized with aminothiouracils

The invention relates to thermoplastic moulding compositions based on polymers of vinyl chloride and containing 0.1 to 5% by weight of a 2-thio-6-aminouracil of the formula I ##STR1## wherein each of R.sup.1 and R.sup.2 independently is a hydrocarbon radical of 1 to 24 carbon atoms which can be substituted by --OH, --COOR.sup.4, --O(C.dbd.O)R.sup.4, --(C.dbd.O)R.sup.4, halogen or amino, and R.sup.3 is hydrogen, acyl of 2 to 24 carbon atoms or --(C.dbd.O)NHR.sup.4, while R.sup.4 is a hydrocarbon radical of 1 to 24 carbon atoms.

The present invention relates to novel stabilised chlorinated 
thermoplastics and to the use of specific uracils for stabilising such 
substrates. 
Uracils are known as stabilisers for PVC from German Auslegeschrift 1 694 
873, e.g. 1,3-dimethyl-6-aminouracil (column 2, lines 2/3). A thiouracil, 
namely 3-phenyl-6-methyl-2-thiouracil, is also known as a stabiliser for 
PVC from U.S. Pat. No. 4,105,627 (column 7, line 26). Finally, German Pat. 
No. 888 167 discloses pyrimidines as stabilisers for PVC, e.g. 
2,4-diamino-6-oxy-pyrimidine. 
It has been found, however, that these known stabilisers do not always 
satisfy the exacting demands of actual practice. Their effectiveness, 
their compatibility with the substrate, and also their stability to heat 
and hydrolysis, are insufficient. Finally, they are also unsatisfactory 
from the toxicological point of view. 
It is the object of this invention to provide stabilisers which do not have 
these drawbacks or which have them to a far lesser degree. 
Accordingly, the present invention provides thermoplastic moulding 
compositions based on polymers of vinyl chloride, said compositions 
containing 0.1 to 5% by weight of a 2-thio-6-aminouracil of the formula I 
##STR2## 
wherein each of R.sup.1 and R.sup.2 independently is a hydrocarbon radical 
of 1 to 24 carbon atoms which can be substituted by --OH, --COOR.sup.4, 
--O(C.dbd.O)R.sup.4, --(C.dbd.O)R.sup.4, halogen or amino, and R.sup.3 is 
hydrogen, acyl of 2 to 24 carbon atoms or --(C.dbd.O)NHR.sup.4, whilst 
R.sup.4 is a hydrocarbon radical of 1 to 24 carbon atoms. 
A hydrocarbon radical R.sup.1 and/or R.sup.2 containing 1 to 24 carbon 
atoms which can be substituted by --OH, --COOR.sup.4, --O(C.dbd.O)R.sup.4, 
--(C.dbd.O)R.sup.4, halogen or amino is e.g. C.sub.1 -C.sub.24 alkyl such 
as branched or, preferably, straight-chain alkyl, in particular C.sub.1 
-C.sub.12 alkyl such as methyl, ethyl, n-propyl, n-butyl or n-octyl; or 
also C.sub.2 -C.sub.24 alkenyl, in particular C.sub.2 -C.sub.12 alkenyl 
such as vinyl or propen-1-yl; or also C.sub.6 -C.sub.24 aryl such as 
phenyl or (C.sub.1 -C.sub.12 alkyl)phenyl such as methylphenyl, 
dimethylphenyl, ethylphenyl or isopropylphenyl; or also C.sub.7 -C.sub.24 
aralkyl such as benzyl, .alpha.,.alpha.-dimethylbenzyl or methylbenzyl, 
e.g. 4-methylbenzyl; or also C.sub.1 -C.sub.24 hydroxyalkyl, in particular 
C.sub.2 -C.sub.12 hydroxyalkyl such as 2-hydroxyethyl; or also esterified 
C.sub.2 -C.sub.24 carboxyalkyl such as C.sub.3 -C.sub.24 
alkoxycarbonylmethyl, e.g. methoxycarbonylmethyl, n-butoxycarbonylmethyl, 
n-octoxycarbonylmethyl or n-C.sub.14 H.sub.29 oxycarbonylmethyl, or also 
C.sub.2 -C.sub.24 acyloxyalkyl, wherein alkyl is preferably methylene or 
1,2-ethylene, such as (C.sub.1 -C.sub.12 alkyl)carbonyloxymethyl or 
2-[(C.sub.1 -C.sub.12 alkyl)carbonyloxy]ethyl, e.g. acetyloxymethyl 
2-acetyloxyethyl, propionyloxymethyl or 2-propionyloxyethyl; or also 
C.sub.3 -C.sub.24 acylalkyl, wherein alkyl is preferably methylene, such 
as (C.sub.1 -C.sub.12 alkyl)carbonylmethyl, e.g. acetylmethyl or 
propionylmethyl; or also C.sub.1 -C.sub.24 haloalkyl, wherein halogen is 
preferably chlorine, such as 2-chloroethyl or 2-chloropropyl; or also 
C.sub.6 -C.sub.24 halophenyl such as chlorophenyl; or also C.sub.6 
-C.sub.24 aminophenyl such as aminophenyl itself. 
R.sup.3 as acyl of 2 to 24 carbon atoms is e.g. C.sub.2 -C.sub.24 
alkylcarbonyl, in particular C.sub.2 -C.sub.18 alkylcarbonyl such as 
acetyl, propionyl, butyryl, n-undecylcarbonyl or n-heptadecylcarbonyl, or 
acetoacetyl. R.sup.3 as --(C.dbd.O)NHR.sup.4, wherein R.sup.4 is a 
hydrocarbon radical of 1 to 24 carbon atoms, is e.g. (C.sub.1 -C.sub.12 
alkyl)aminocarbonyl such as methylaminocarbonyl, ethylaminocarbonyl or 
n-propylaminocarbonyl. 
In the practice of this invention it is preferred to use those uracils of 
the formula I, wherein R.sup.1 and R.sup.2 have the given meanings and 
R.sup.3 is hydrogen. It is most preferred to use those uracils of the 
formula I, wherein R.sup.1 and R.sup.2 are C.sub.1 -C.sub.12 alkyl and 
R.sup.3 is hydrogen, especially those compounds specified in the Examples. 
The uracils employed in the practice of this invention are known and can be 
obtained by known methods, e.g. as described in U.S. Pat. No. 2,598,936. 
Those compounds which are novel can be prepared by methods analogous to 
known ones, e.g. as described in the above U.S. patent. 
The uracils employed in the practice of this invention are most suitable 
for protecting chlorinated thermoplastics against heat-induced 
degradation. They can be incorporated in the thermoplastics to be 
stabilised singly or in admixture with one another, before processing in 
conventional apparatus, and in respective amounts of 0.1 to 5% by weight, 
preferably 0.2 to 1.5% by weight, based on the entire composition. 
Examples of chlorinated thermoplastics are polyvinylidene chloride and, 
preferably, polymers of or based on vinyl chloride. Suspension and mass 
polymers, and emulsion polymers having a low content of emulsifier, are 
preferred. Polyvinyl chloride can be plasticised or rigid PVC. Processing 
by injection moulding, calendering and extruding is particularly 
preferred, as is also the production of plastisols. 
Examples of comonomers for thermoplastics based on vinyl chloride are: 
vinylidene chloride, trans-dichloroethane, ethylene, propylene, butylene, 
maleic acid, acrylic acid, fumeric acid or itaconic acid. 
Depending on the end use, further additives can be incorporated in the 
moulding compound before, during or after the addition of the stabiliser 
or stabiliser mixture. Examples of further additives together with which 
the stabilisers of the invention can be used, are: antioxidants such as 
2,6-dialkylphenols, derivatives of alkylated hydroquinones, hydroxylated 
thiodiphenyl ethers, alkylidene bisphenols, O-, N- and S-benzyl compounds, 
hydroxybenzylated malonates, hydroxybenzyl aromatics, s-triazine 
compounds, amides of .beta.-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic 
acid, esters of .beta.-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid, 
esters of .beta.-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid, 
esters of .beta.-(5-tert-butyl-4-hydroxyphenyl)-acetic acid, 
acylaminophenols, benzylphosphonates, aminoaryl derivatives, UV absorbers 
and light stabilisers such as 2-(2'-hydroxyphenyl)-benztriazoles, 
2,4-bis-(2'-hydroxyphenyl)-6-alkyl-s-triazines, 2-hydroxybenzophenones, 
1,3-bis-2-(2'-hydroxybenzoyl)-benzenes, esters of substituted or 
unsubstituted benzoic acids, acrylates, nickel compounds, sterically 
hindered amines, oxalic acid diamides, metal deactivators, phosphites, 
compounds which decompose peroxide, polyamide stabilizers, basic 
co-stabilisers, nucleination agents or other additives, for example 
plasticisers, lubricants, emulsifiers, fillers, carbon black, asbestos, 
kaolin, talc, glass fibres, pigments, fluorescent whitening agents, flame 
retardants, antistatic agents. 
Examples of further additives together with which the stabilisers of the 
present invention can be used are listed on pages 18-24 of German 
Offenlegungsschrift 2 427 853. 
Preferred co-stabilisers are calcium/zinc carboxylates, organo-tin 
stabilisers and epoxides.

The invention is illustrated in more detail by the following Examples, in 
which parts and percentages are by weight. 
EXAMPLE 1: 
A dry blend consisting of 100 parts of S-PVC (K value 64), 20 parts of 
dioctyl phthalate, 3 parts of epoxidised soybean oil (REOPLAST 39.RTM.), 
0.5 part of phenyldidecylphosphite (IRGASTAB CH 300.RTM.) and 1.5 parts of 
1,3-di-n-butyl-2-thio-6-aminouracil (compound 1) is rolled for 5 minutes 
on a mixer roll at 170.degree. C. and then samples having a thickness of 
0.3 mm are taken from the sheet obtained. These samples are subjected to 
heat in a test oven at 180.degree. C. and every 5 minutes the thermal 
ageing of a sample is determined according to the Yellowness Index of ASTM 
D 1925/70. The results are reported in Table 1. 
The procedure is repeated using a different dry blend consisting of 100 
parts of S-PVC (K value 64), 2 parts of epoxidised soybean oil (REOPLAST 
39.RTM.), 0.5 part of trinonylphenylphosphite, 1 part of calcium/zinc 
stearate and 0.8 part of compound 1. The results are reported in Table 2. 
Comparable results are obtained by replacing 
1,3-di-n-butyl-2-thio-6-aminouracil with one of the following compounds: 
1,3-dimethyl-2-thio-6-aminouracil 
1,3-diethyl-2-thio-6-aminouracil 
1,3-di-n-octyl-2-thio-6-aminouracil or 
1-methyl-3-n-butyl-2-thio-6-aminouracil. 
TABLE 1 
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Heat test: static/dynamic, mixer roll temperature 170.degree. C., 
rolling time 5 min, 
oven temperature 180.degree. C., thickness of sheet 0.3 mm 
Basic formulation: S-PVC (K value 64) 100 parts, 
dioctyl phthalate 20 parts, 
epoxidised soybean oil 3 parts, 
phenyldidecylphosphite 0.5 part 
Yellowing (YI of ASTM 
Test Amount D 1925-70) and ageing (min) 
No. Test Compounds 
pph 0 15 30 45 60 75 
______________________________________ 
1 -- -- 10 83 &gt;100 
2 Compound 1 1.5 3 5 10 25 40 51 
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TABLE 2 
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Heat test: static/dynamic, mixer roll temperature 170.degree. C., 
rolling time 5 min, 
oven temperature 180.degree. C., thickness of sheet 0.3 mm 
Basic formulation: S-PVC (K value 64) 100 parts, 
epoxidised soybean oil 2 parts, 
trinonylphenylphosphite 0.5 part, 
Ca/Zn stearate 1 part 
Yellowing (YI n. ASTM D 
Test Amount 1925-70) and ageing (min) 
No. Test Compounds 
pph 0 15 30 45 
______________________________________ 
1 -- -- 44 86 &gt;100 
2 Compound 1 0.8 3 7 33 &gt;100 
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