Self-emulsifying liquid stabilizers
View Patent ↗A process for stabilising a natural or synthetic organic polymer or copolymer obtained from a water based latex or emulsion of the polymer or copolymer comprising adding to the later or emulsion prior to coagulation of the polymer or copolymer a substantially water-free self-emulsifying liquid stabiliser mixture comprising (a) a phosphite or phosphonite stabiliser; (b) a phenolic antioxidant and (c) an emulsifying agent. The preferred stabiliser package is a blend of 2 parts by weight liquid phosphite stabiliser to 1 part by weight liquid phenolic antioxidant which has dissolved in it a fatty acid ester emulsifier.
1. A process for stabilising a natural or synthetic organic polymer or copolymer obtained from a water based latex or emulsion of the polymer or copolymer comprising adding to the latex or emulsion prior to the coagulation of the polymer a substantially water-free self-emulsifying liquid stabiliser mixture comprising (a) a phosphite or phosphonite stabiliser; (b) a phenolic antioxidant and (c) an emulsifying agent,
wherein the ratio of phosphite or phosphonite stabiliser to the phenolic antioxidant in the liquid stabilizer mixture is about 2:1 parts by weight.
2. A process as claimed in claim 1 wherein the phosphite or phosphonite stabiliser and the phenolic antioxidant are liquid at room temperature, molten between 50 and 120° C. or are used in solution.
3. A process as claimed in claim 2 wherein the phosphate stabiliser is liquid at room temperature and is selected from the group consisting of:
Tris nonylphenyl phosphite
Tris dinonylphenyl phosphite
2,4-Dinonylphenyl bis(4-nonylphenyl)phosphite
Triphenyl phosphite
Tris(methylphenyl)phosphite
Diphenyl isodecyl phosphite
Phenyl diisodecyl phosphite
Triisodecyl phosphite
Diphenyl isooctyl phosphite
Phenyl diisooctyl phosphite
Triisooctyl phosphite
Tri(tridecyl)phosphite
Tristearyl phosphite
Trilauryl phosphite
2-Butoxyethyl diisodecyl phosphite
2-Ethylhexyl diphenyl phosphite
Tri 2-ethyhexyl phosphite
Bis(2-ethylhexyl)nonylphenyl phosphite
Tetraphenyl dipropylene glycol diphosphite
Tris(dipropylene glycol)phosphite
Poly(dipropyleneglycol)phenyl phosphite
Alkyl(C 12-15 )bisphenol A phosphite,
and Alkyl(C 10 )bisphenol A phosphite
4. A process as claimed in claim 2 wherein the phosphonite stabiliser is Tetrakis(2,4-di-tert-butylphenyl)4,4′-diphenylene diphosphonite melting in the range 75° C. to 95° C.
5. A process as claimed in claim 1 wherein the phenolic antioxidant is liquid at room temperature and is a mixture of C 13 -C 15 linear and branched alkyl esters of 3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionic acid, octyl 3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate, 2,2′-methylene bis(4-methyl-6-nonylphenol), 2,6-bis(alpha- methylbenzyl)-4-methylphenol, styrenated phenol (mixture of mono-, di- and tri), or 2,4-dimethyl-6-(1-methylpentadecyl)phenol and tocopherols.
6. A process as claimed in claim 1 wherein the phenolic antioxidant is a soluble antioxidant and is 1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane, a polymeric sterically hindered phenol, or octadecyl 3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate.
7. A process as claimed in claim 1 wherein the emulsifying agent is a non-ionic surfactant, an anionic surfactant, a cationic surfactant or an amphoteric surfactant or blends thereof.
8. A process as claimed in claim 7 wherein the non-ionic surfactant is selected from the group consisting of fatty alcohols, partial fatty acid esters of multivalent alcohols, sorbitan esters of fatty alcohols, polyethyleneglycol ethers, polyethyleneglycol fatty acid esters and polyethyleneglycol sorbitan fatty acid esters.
9. A process as claimed in claim 8 wherein the emulsifying agent is ethoxylated sorbitol stearate or oleic acid ethoxylate.
10. A process as claimed in claim 7 wherein the anionic surfactant is an alkali soap, an amine soap, an alkyl sulphate or an alkylsulphonate.
11. A process as claimed in claim 7 wherein the cationic surfactant is a quatemary ammonium salt or a pyridium salt.
12. A process as claimed in claim 7 wherein the amphoteric surfactant is a phospholipid or an ampholyte soap.
13. A process as claimed in claim 1 wherein the phosphite or phosphonite/phenol blend is present in the dry polymer in an amount between 0.3 and 5% by weight.
14. A process as claimed in claim 13 wherein the phosphite or phosphite/phenol blend is present in the dry polymer in an amount between 0.3 and 1% by weight.
15. A process as claimed in claim 1 wherein the phosphite or phosphonite/phenol blend is mixed with at least 5% by weight of the emulsifying agent.
16. A process as claimed in claim 1 wherein the substantially water-free liquid self-emulsifying stabiliser mixture is used in combination with other additives.
17. A process as claimed in claim 1 wherein the organic polymer is selected from aqueous emulsions of natural or synthetic rubbers such as latex or latexes based on carboxylated styrene-butadiene copolymers.
18. A process as claimed claim 1 wherein the organic polymer is selected from the group consisting of natural or synthetic rubber such as acrylic rubbers, polyisoprene, polybutadiene, polychloroprene, styrene/butadiene rubber and EPDM.
19. An article comprising a natural or synthetic polymer or copolymer obtained from the process of claim 1 .