CA2177737C - Stabilizer system for non yellowing polymer composition - Google Patents

Stabilizer system for non yellowing polymer composition Download PDF

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CA2177737C
CA2177737C CA002177737A CA2177737A CA2177737C CA 2177737 C CA2177737 C CA 2177737C CA 002177737 A CA002177737 A CA 002177737A CA 2177737 A CA2177737 A CA 2177737A CA 2177737 C CA2177737 C CA 2177737C
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styrene
copolymer
stabilizer system
acrylonitrile
benzotriazole
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CA2177737A1 (en
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Moh-Ching Oliver Chang
Chuan-Ju Chen
Robert Allen Padwa
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Bayer Antwerpen NV
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Bayer Antwerpen NV
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Abstract

A stabilizer system for styrenic polymers consisting essentially of (a) a benzotriazole;
(b) an oligomeric condensate of N,N'-(2,2,6,6-tetramethylpiperidyl) hexamethylene diamine and 2,4-dichloro-6-morpholino-1,3,5-s-triazine;
and (c) tris (3,5-d9-tert-butyl-4-hydroxybenzyl) isocyanurate with the proviso that the stabilizer system does not contain phosphites or phosphonites stabilizers. Further, an alternate embodiment is a stabilizer system for styrene polymers consisting essentially of (a) a benzotriazole;
(b) a hindered amine light stabilizer selected from the group consisting of (i) bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and (ii) bis-(1,2,2,6,6-pentamethyl-4-piperdinyl) ester of (3,5-di-tert-butyl-4-hydroxybenzyl)-butyl malonate; and (c) tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate with the proviso that the stabilizer system does not contain phosphites or phosphonites stabilizers.

Description

Og_12 (8932) A

STABILIZER SYSTEM FOR NON YELLOWING
POLYMER COMPOSITION
The present invention relates generally to non-yellowing thermoplastic polymers and more particularly to non-yellowing thermoplastic styrenic polymers containing a stabilizer system.
Styrenic thermoplastic compositions such as ABS compositions and similar styrene-acrylonitrile copolymer blends containing rubbers grafted with styrene-acrylonitrile copolymers exhibit undesirable yellowing which may develop upon storage of the thermoplastics in the dark or on exposure to warm oxidizing aqueous conditions such as occur in warm spas fabricated from such thermoplastic or may be caused by migration of yellow enhancing ingredients from materials in contact with the thermoplastics. Such yellowing is believed to occur due to the transformation of the antioxidants in the thermoplastics to highly chromophoric species. While the antioxidants serve to protect the polymer from oxidation during melt processing and to enhance weatherability and aging resistance, the interaction of the multiple components of antioxidant and UV stabilizer systems can sometimes result in undesirable side reactions which produce yellowing although polymer degradation itself has been impeded.
There is therefore a need for heat stable, weather resistant styrenic thermoplastic compositions capable of being molded into shaped articles possessing an acceptable resistance to the yellowing which can occur upon storage in the dark or upon exposure to yellowing agents.
The present invention provides such compositions comprising a stabilizer system for styrenic polymers, comprising a benzotriazole UV
absorber, a hydroxybenzylisocyanurate primary antioxidant, and an oligomeric condensation product of N,N' (2,2,6,6-tetramethylpiperidyl) alkylene diamine and a 6-amino-2,3-dichloro-1,3,5-s-triazine. Optionally a thiodipropionate can be WO 95/15358 ~ "o, . CT/US94/13801 added to function as a secondary antioxidant and a zinc dialkyl-dithiocarbamate can be used to mitigate the yellowing attributed to phenolic antioxidants migrating into the styrenic composition from external sources.
The UV stabilizer can be one or more of the benzotriazole type, especially a hydroxyalkylphenylbenzotriazole as represented by commercially available materials such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Tinuvin P, trademark of Ciba-Geigy), 2-(2'-hydroxy-3',5'-di-tert butylphenyl)benzotriazole, 2-(2'-hydroxy 3',5'-di-tert butylphenyl)-5-chlorobenzotriazole (Tinuvin 327), 2-(2'-hydroxy 3',5'-di-tert-amylphenyl)benzotriazole (Tinuvin 328), 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole (Cyasorb UV5411, trademark of American Cyanamid, Inc.) and the like. The UV stabilizer or stabilizers should be used in sufficient concentration to provide adequate stability against exposure to UV light.
The oligomeric condensation product of a N,N'-(2,2,6,6-tetramethylpiperidyl)alkylenediamine and a 6-amino-2,4-dichloro-1,3,5-s-tr.iazine includes those described in U.S. Patents 4,086,204 and 4,331,586. The alkylene group of the N,N'-(2,2,6,6-tetramethylpiperidyl)alkylene diamine is advantageously a C2-C2o alkylene group which may be straight-chained or branched and may be interrupted by aza, oxa or thin groups. Preferably the alkylene is hexamethylene. The amine group of the 6-amino-2,4-dichloro-1,3,5-s-triazine is derived from a primary or secondary Cl-Cg alkylamine or from piperidine or morpholine. Preferably the amine is morpholine. The degree of oligomerization is advantageously in the range of about 1.2 to about 5 ...., WO 95/15358 2 1 ~ 7 / ~ PC1'/US94/13801 to provide an oligomer which is readily dispersed in and compatible with the styrenic polymer.
The hydroxybenzylisocyanurates useful in the present invention include those described in U.S. Patent 3,531,483. Advantageously the hydroxybenzylisocyanurate is a symmetrical tris-(3,5-di-tert-alkyl-4-hydroxybenzyl)isocyanurate selected from the group consisting of:
tris-(3,5-di-tert-butyl-4-hydroxybenzyl) l0 isocyanurate, tris-(3,5-di-tert-amyl-4-hydroxybenzyl)isocyanurate, tris-(3-tert-butyl-5-t-amyl-4-hydroxybenzyl)isocyanurate, tris [3,5-di-(1-methyl-1-ethylpropyl)-4-hydroxybenzyl]-isocyanurate, tris-[3,5-di-(1,1,2,2-tetramethylpropyl)-4-hydroxybenzyl]isocyanurate, and tris-[3,5-di-(1,1-dimethylpentyl)-4-hydroxybenzyl]isocyanurate to provide a stabilizer system capable of conferring on the styrenic polymer a satisfactory balance of heat stability, weatherability and resistance to yellowing.
Optionally a thiodipropionate may be included in the stabilizer system to act as a secondary antioxidant capable of acting as a hydroperoxide decomposer. In contrast to another commonly used group of secondary antioxidants comprising phosphites and phosphonites, the thiodipropionates when they are included in the stabilizer system for styrenic polymers, inhibit yellowing in the dark. The thiodipropionates however do not effectively reduce yellowing of the styrenic polymer spa materials in contact with warm, anti-bacterial bleaching solutions used in such spas. The thiodipropionates which may be used to advantage in this aspect of the present invention include the dialkyl thiodipropionates of C12-C18 alkanols. Distearyl thiodipropionate is a preferred thiodipropionate because of its ease of dispersion in the styrenic polymer and its compatibility therewith.
Another group of compounds which may be used in the present stabilizer system is provided by the dialkyl-dithiocarbamates of zinc. Although they can effectively destroy peroxides and thus inhibit yellowing caused by autoxidation of phenolic stabilizers, they may increase the initial yellowness of styrenic polymers and may impair their weatherability. They are therefore preferably used in low concentration and limited to stabilizer systems for styrenic polymers used indoors and are used advantageously when the stabilized styrenic polymer is likely to come into contact with substrates containing readily autoxidized migratable phenolic stabilizers, since they inhibit yellowing which can result from such autoxidation.
The stabilizer system of the present invention is used in an amount necessary for the requisite degree of stabilization of styrenic polymers and can be used advantageously in concentration of up to 3 weight percent of the styrenic polymer. Advantageously the stabilizer system comprises from about 20 to about 70 parts by weight of the benzotriazole, from about i8 to about 60 parts by weight of the oligomeric condensation product of the N,N~-(2,2,6,6-tetramethylpiperidyl) alkylenediamine and the 6-amino-2,4-dichloro-1,3,5-s-triazine and from about 12 to about 50 parts by weight of the hydroxybenzylisocyanurate. When a thiodipropionate is used, it is added to provide additionally from about 12 to about 40 parts by weight of the stabilizer system. The dialkyldithiocarbamate can be added to provide ", WO 95/15358 ~ ~ ~ PCT/US94/13801 additionally from about 3 to about 8 parts by weight of the stabilizer system provided that the amount of dialkyldithiocarbamate in the stabilized styrenic polymer is not more than 0.1 weight 5 percent.
The styrenic thermoplastic polymer may be selected from the group consisting of polystyrene, styrene-acrylonitrile copolymer, a-methylstyrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-butadiene-a-methylstyrene copolymer, acrylonitrile-styrene-(C3-C1o alkyl acrylate) copolymer, rnethacrylate-butadiene-styrene copolymer, styrene-methyl methacrylate copolymer, polystyrene blended with a polybutadiene to which styrene has been grafted, styrene-acrylonitrile copolymer blended with a poly(C3 to Clo alkyl acrylate) rubber grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with a polybutadiene rubber grafted with a styrene-acrylonitrile copolymer, Styrene-acrylonitrile copolymer blended with an ethylene-propylene-diene copolymer rubber grafted with a styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer blended with a poly(C3 to alkyl acrylate) rubber grafted with a styrene-methyl methacrylate copolymer, styrene-methyl methacrylate copolymer blended with a polybutadiene grafted with a styrene-methyl methacrylate .. 30 copolymer and styrene-methyl methacrylate copolymer blended with an ethylene-propylene-diene rubber a grafted with a styrene methyl methacrylate copolymer.
Preferably the styrenic polymer is selected from the group consisting of styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer blended with a polybutadiene grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with a poly(C3 to Clo alkyl acrylate) rubber grafted with a styrene-acrylonitrile copolymer and styrene-acrylonitrile copolymer blended with an ethylene-propylene-diene copolymer rubber grafted with a styrene-acrylonitrile copolymer.
The components of the stabilizer system can be added together or separately to the styrenic polymer and blended therein by any conventional melt blending process. Alternatively, in the preparation of styrenic polymer polyblends, individual components of the stabilizer system may be added in whole or in part to one or more individual polymer components of the polyblend either during the manufacture of such polymer components or prior to introduction of such polymer components into the polyblend.
In addition to the stabilizer system, other additives such as impact modifiers, pigments, fillers, lubricants and flow aids may be included in the thermoplastic styrenic polymer provided such additives do not significantly affect the yellowing which can develop in the dark or in the presence of oxidation environments.
The stabilizer system of the present invention and its stabilizing effect on styrenic polymers is further illustrated but not limited by the examples set forth below.
WORKING EXAMPLES
In the working examples set forth below, the following components are used:
ASA - a poly(butyl acrylate) rubber grafted with a styrene-acrylonitrile 08-12(8932)A
copolymer. The weight ratio of rubber to graft copolymer is 10:12;
the weight ratio of styrene to acrylonitrile is 68:32 AES - an ethylene propylene diene rubber grafted with styrene-acrylonitrile copolymer supplied by Uniroyal under the tradename Royaltuff 372 SAN - a copolymer of 68 weight percent styrene and 32 weight percent acrylonitrile Tinuvin 328a - 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole Cyasorb - 2-hydroxy-4-n-octyloxybenzophenone UV531b Cyasorb - 2-(2'-hydroxy-5'-tert-octylphenyl) UV5411 benzotriazole Tinuvin 144 - bis-(1,2,2,6,6-pentamethyl-4-piperdinyl) ester of (3,5-di-tert-butyl-4-hydroxybenzyl)-butyl malonate Tinuvin 622LD- polymer of dimethyl succinate and 2,2,6,6-tetramethyl-4-hydroxy-1-hydroxyethylpiperidine Tinuvin 765 - bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate Tinuvin 770 - bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate Cyasorb - an oligomeric condensate of N,N'-UV3346 (2,2,6,6-tetramethylpiperidyl) hexamethylene diamine and 2,4-dichloro-6-morpholino-1,3,5-s-triazine, wherein the degree of oligomerization is about 2.0 to 2.5 Ionol~ - 2,6-di-tert-butyl-p-cresol Irganox~ 1076 - octadecyl 3,5-di-tert-butyl-4-hydroxy-hydrocinnamate Irganox~ 1010 - tetrakis[(3,5-di-tert-butyl-4-hydroxy hydrocinnamoyloxymethyl)]
methane 08-12 (8932) A
_g_ Irganox~ 3114 - tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate Irganox~ 1,2-bis(3,5-di-tert-butyl-4-hydroxy-MD1024 hydrocinnamoyl) hydrazine Irganox 1035 - thioethylene bis(3,5-di-tert-butyl-4-hydroxy hydrocinnamate) l0 Irganox 1098 - N,N'-hexamethylene bis(3,5-di-tert-butyl-4-hydroxy hydrocinnamate) Ethanox 3304 - 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene Topanol CAe - 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane Santonox Rf - 4,4'-thio-bis(6-tert-butyl-m-cresol) Naugard P9 - tris(p-nonylphenyl) phosphite Nauga_rd 445 - 4,4'di(Ct,Ex-dimethylbenzyl)d~phenylamine Irgafos 168a - tris(2,4-di-tert-butylphenyl) phosphite Weston 618h - distearyl pentaerythritol diphosphite Ethanox 398 - 2,2'-ethylidene bis(4,6-di-tert-butylphenyl) fluorophosphonite Sandostab - tetrakis(2,4-di-tert-P-EPQi butylphenyl) 4,4'-biphenzlene diphosphonite Cyanox 711b - di-(tridecyl) thiodipropionate DSTDP - distearyl thiodipropionate Ethyl - zinc diethyl dithiocarbamate Zimate~
Zn St - zinc stearate Ti-Pure - rutile titanium dioxide (97%) R101k Tioxi.de - rutile titanium dioxide (92%) Registered trademarks:
a Ciba-Geigy Corporation b American Cyanamid Company 8 ~ ~ 7 ~ ~' 3 7 ~ PCT/US94113801 ,A~.."
c Neville Chemical Company d Ethyl Corporation a Imperial Chemical Industries, plc.
f Monsanto Company g Morton Thiokol Corporation h General Electric Company i Sandoz Corporation j R.T. Vanderbilt Company, Inc.
k E. I. duPont de Nemours and Company, Inc.
1 Tioxide Company PREPARATION f~l~ ~~EST ~S~ PLES
Polymer blends containing stabilizer systems are prepared by adding the ingredients of the blend to a Banbury mixer of 3.4 kg capacity operated to provide a dump temperature of 205 to 210°C. The circulating oil temperature is about 105°C, the rotor speed is 110 rpm, the ram weight air pressure is 482 kPa, the mill roll front pressure is 517 kPa and the back pressure is 413 kPa. The blend is extruded and pelletized in a Cumberland pelletizer set at 6 out of 10 scale.
Injection molded plaques 7.62 cm x 10.2 cm are prepared from the pellets using an Engel injection molding machine operated at a stock temperature of 257°C, injection speed of 5.08 cm per second. The injection time is approximately 2.2 seconds, cooling time 10 seconds, holding time 10 seconds, back pressure 1000 kPa, screw refill speed 43 percent of full speed and scr~e~w refill stroke 6.35 cm with 0.38 cm cushion.
EVALUATION OF YELLOWING ;~~1 ~('~E DARK i(YID~
Without prior light exposure, the polyblends do not yellow in the dark. Therefore a standard pre-exposure of test samples to light is carried out by the method described in ASTM D2565-89. The Atlas Model Ci65 Weather-Ometer is used.

-12 (8932) A
The light source is Xenon arc with borosilicate/borosilicate inner and outer fillers.
The lrradiance is 0.35 watt/m2 at 340 nm wavelength. The black panel temperature is 5 controlled at 63 t 3'C. The continuous light-on cycle procedure is used with intermittent water spray providing relative humidity in the range of 30 to 100$.
The yellowness index (b) of the test 10 samples is measured before (bo) and after W
exposure of 50 kJ.m-2(bb). The samples are then aged in the dark in an air circulated oven at 60'C
and the yellowness index (ba) is determined at increasing intervals of time. The change in yellowness index versus bb and by is denoted by (db) ~ and (db) a0 respectively.
EVALUATION OF SPA UNDER WATER YEL OWING (SUWY~
A 34 liter glass tank filled with pump circulated solution of Bioguard (sodi.um dichloro-s triazinetrione) maintained at 40'C and an active chlorine and chloride level of 25 ~ f5 ppm is used in the determination of SUWY. The test is done in a laloor_atorv hood. Indoor ambient. light exposure of approximately 12 tours per day is applied. Without such exposure, no yellowing occurs. The test samples are placed in the tank and the yellowness index (b) is determined at intervals of time.
W EATN ERAB I LITY
Weatherability is judged by the difference in impact resistance of samples exposed to accelerated weathering conditions and control examples not so exposed. Exposure is carried out under the conditions set forth in ASTM 2565-89.
Results are expressed as follows:

WO 95/15358 ~ '~ '~ ~ PCTIUS94/13801 Rating o Retention of Impact Strenctth 0 <35 EFFECT OF HINDERED PHENOLIC ANTIOXIDANT
A series of polyblends comprising 96.1 parts by weight of a blend of 55.6 parts by weight of ASA, 44.4 parts by weight of SAN, 0.30 parts by weight of hindered phenolic antioxidant, 0.75 parts by weight of Tinuvin 328, 0,75 parts by weight of Tinuvin 770, 2 parts by weight of 2-(2-butoxyethoxy)ethanol, 0.1 part by weight of Dow Corning DC200 silicone oil and 6 parts by weight of Ti-Pure 8101 titanium dioxide are blended in the Banbury mixer and injection molded to provide test samples. The data for YID and SUWY after 14 days are presented in Table 1.

EFFECT OF HINDERED PHENOLIC ANTIOXIDANT
Hindered Phenolic Example Antioxidant YID SUWY
o ~.d~b db 1 None 6.41 -1.68 7..14 0.40 2 Ionol 6.62 2.38 5.07 1.57 3 Irganox 1076 6.75 -1.42 1.37 3.13 4 Zrganox 1010 7.15 -1.36 1.65 1.12 3 5 Irganox 3114 6.72 -i.77 1.05 0.7c 6 Ethanox 330 6.82 -0.16 :?.43 1.12 7 Topanol CA 7.04 -1.51 1.25 1.20 8 Santanox 6.92 -0.60 1.42 1.65 R

9 Irganox MD1024 6.22 -0.88 1.46 0.80 4 10 Irganox iC35 6.06 -0.87 1.61 2.79 11 Irganox 1098 6.12 -0.99 :1.55 1.34 SUBSTITUTE SNEEf (RULE 26) wo 9ms3s~ '~ ~~ ~ ,~.~ ~ ~wss,r~:~~
The data demonstrate that xonol and Irganox 1076 confer the worst YID and SUWY
respectively. Tha formulation containing no phenolic antioxidant ydllows least. Among the formulations containing phenolic antioxidant, the formulation containing Irganox 3114 showed the least yellowing in both the YID and St?WY tests.
FFF~cT o,~ e~NZO~ ~ z~yE,~L1'r soT~ HER
A series of polyblends is prepared comprising 30.3 parts by weight of ABA, 36.5 parts by weight of AES, 24.3 parts by weight SAN, 2 parts by weight of 2-(2-butoxy~thoxy)ethanol, 0.1 part by weight of Dow Corning DC200 silicone oil, 6 parts by weight of Ti-Pure 8101 titanium oxide and 0.75 parts by weight of benzotriazole W absorber. The data for YID and.~~SUWY of the polyblmnds are set forth in Table .xl.
' T88LE_Ih a o ,~,F,~' C2 OF HENZ ~ _~sottsF.R
~.~.~,r~, Y~_ .
~o .~,~.so .ab 12 Tinuvin 3x8 6.91 -1.7~ 1.47 0.32 13 Cyasorb W5411 6.83 -i.~l 1.45 0.98 14 Cyasorb W531 7.27 -1.83 1.42 0.29 The data stow that a benxotriazole W
absorber makes little contribution to YzD. Tlnuvin 328 and Cyaeorb W531 are superior to Cyasorb 3 5 W5411 in the StJWY test .
T.Tfa~i'1' A eerier of polyblends is prepared comprising 30.0 parts by weight of ASA, 36.0 parts by weight of AES, 24.0 parts by weight of SAN. 2 ao parts by weight of 2-(2-butoxysthoxy)ethanol, part by weight of Dow Corning DCZ00 oilicone oil, 6 AMENDED SHEET
IPEA/cP

-12(8932)A

parts by weight of Ti-Pure 8101 titanium oxide, 0.75 parts by weight of Tinuvin 328, 0.3 parts by weight of Irganox 1076 and 0.75 parts by weight of hindered amine light stabilizer (HAL:;). The YID
and SUWY data for the polyblends are presented in Table III.
TABLE III
EFFECT OF fi.Ar.S
Example ___ - III~I_S -_f_ YIp (dbl.~ . dI bl..
None 7. OA -1.59 1.53 0.58 16 Tinuvin 144 7.10 -0.31 2.79 7.10 17 Tinuvin 622LD 7.42 -1.54 1.70 0.57 15 18 Tinuvin 765 7.16 0.25 3.35 2.85 19 Tinuvin 770 7.54 3.18 6.52 3.36 Cyaeorb UV3346 7.55 '1.26 2.24 2.11 This series of screening experiments was 20 conducted with Irganox 1076, one of the worst offenders for its contribution to YID and SUWY, to ensure differentiation between the various HALS.
In general the addition of HALS increases the yellowing index of the polyblend. T'inuvin 622LD
imparts the lowest degree of yellowing. Cyasorb 3346 is about equivalent to Tinuvin 622LD in its contribution to YID, and its contribution to SUWY
is significantly less than that of the other HALS
except Tinuvin 622LD. Unfortunately Tinuvin 622LD
provides poor weatherability to styrenic polymers because of its incompatibility. Hence Cyasorb 3346 was selected for stabilizer systems comprising the best performing phenolic antioxidant, Irganox 3114.
EFgECT OF SECONDARY ANTIOXIDr~N~r A series of polyblends is prepared comprising 29.9 parts by weight of ASA, 35.9 pads by weight of AES, 24.0 parts by weight of SAN, 2 parts by weight of 2-(2-butoxyethoxy)ethanol, 0.1 r. ..

08-12 (8932) A ~ s~ ~ ~ ~ ~ ~ a part by weight of Dow Corning DC200 silicone oil, 6 parts by weight of Ti-Pure titanium dioxide, 0.75 parts by weight of Tinuvin 328, 0.75 parts by weight of Tinuvin 144, 0.3 parts by weight of Ionol and 0.3 parts by weight of secondary antioxidant.
The YID and SUWY data of the polyblends are set forth in Table IV.
TABLE IV
AFFECT OF SECONDARY ANTIOXIDANT
Example Secondary YID
Antioxldan_t b d( b 1.., ldb 1.~ db 21 None 6.94 13.07 7L5.91 2.83 22 Naugard P 6.84 11.84 7L4.66 3.84 23 ~Irgafoe 168 6.90 12.86 :15.75 1.60 24 Weston 618 6.83 16.23 19.01 1.68 Ethanox 398 6.91 14.20 17.13 1.84 2 0 26 Santoetab P-EPQ 6.97 17.29 20.20 1.17 27 DSTDP 7.01 1.12 4.04 2.29 28 Irganox HD1024 6.73 10.34 13.07 2,76 29 Naugard 445 6.93 16.44 18.26 2.18 Ethyl Zlmate 10.24 -2.20 2.05 0.59 2 5 31 Zn St 8.33 13.23 16.32 1.38 32 Cyanox 711 6.64 1.54 4.28 2.27 In this series of screening experiments 0.3 parts of Ionol is added to the polyblend with 30 the deliberate intention of causing yellowing and finding secondary antioxidants which inhibit such yellowing from undesirable phenolic: antioxidants which may be present in polyblend components or may migrate from materials in contact with the polyblends. Although phosphites are commonly suggested to inhibit phenolic antioxidant yellowing, none of them (Examples :22 to 24 using phosphites and P;xamples 25 and 26 using phosphonites) are effective in the present system and indeed some of them intensify the yellowing. DSTDP and Cyanox 711 decrease YID of the polyblends but are ineffective v'""' WO 95115358 ~ ~' 7 PCTIUS94/13801 in reducing SUWY. Dithiocarbamates such as Ethyl Zimate are very effective in decreasing YID and SUWY, however initial yellowness is increased.
EFFECT OF ETHYL ZIMATE ON INITIAL ~'ELLOWING
5 ~ A series of polyblends of composition similar to the series of table IV but containing various amounts of Ethyl Zimate is prepared. The initial yellowness data are presented in Table V.
TABLE V
10 EFFECT OF ETHYL ZIMATE C'C~TCENTRATION ON INITIAL
YELLOWNESS YID AND SUWY
Concentration of Ethyl Example Zimate , o YID _ Shy b ~.db ) ~,o db b db 33 0.3 10.24 -2.20 2.05 0.59 34 0.1 8.10 3.75 7.04 1.32 35 0.05 7,75 6.50 9.48 --36 0.025 6.95 7.56 10.31 --37 0.0 6.94 13.07 15.91 2.83 While the initial yellowing of the polyblend is reduced with lower concentration of Ethyl Zimate the ability to inhibit the YID and SUWY caused by antioxidants such as Ionol which generate highly colored oxidation products is lessened.
COMPARISON OF STA,~IL~ZER SYSTEMS
A statistical experimental design is performed to determine superior stabilizer systems for a polyblend of 33.3 parts by weight of ASA, 40 parts by weight of AES, 26.7 parts by weight of SAN, 7.5 parts by weight of Tioxide TR-63 titanium dioxide, 2 parts by weight of 2-(2-butoxyethoxy)ethanol, 0.1 parts by weight of Dow Corning DC 200 silicone oil and up to about 2 parts by weight of stabilizer system. From the data generated, the stabilizer systems listed in Table SUBSTITUTE SHEET (RULE 26) WO 95/15358 ~ ~ ~ ~ PCT/US94/13801 VI are rated for (db)ao, (db)ab after 14 days of YID
and for db after 14 days of SUWY and for weatherability. In the ratings 5 is highest and 0 is lowest.
TABLE VI

COMPARISON OF STABILIZER
SYSTEMS

Stabilizer Example Tinuvin 328 1.2 1.2 0.75 1.2 0.40.95 1.2 Tinuvin 144 -- -- 0.75 0.3 0.8-- --Cyasorb 3346 -- -- -- -- -- 0.55 0.3 Irganox 3114 0.6 0.5 0.3 0.3 0.60.3 0.3 DSTDP __ __ __ __ __ __ __ Et Zimate -- 0.1 -- -- -- -- --(db),~ 5 5 0 4 1 0 4 (db)~ 5 5 2 3 1 1 4 (db)SUWY 5 5 1 4 3 5 5 Weatherability 3 2 5 5 5 5 5 COMPARISON OF STABILIZER SYSTEMS.
CONT.

Stabilizer Example Tinuvin 328 0.4 0.4 0.4 0.4 0.750.75 2 Tinuvin 144 0.8 -- 0.4 -- 0.35--Cyasorb 3346 -- 0.8 0.4 0.5 -- 0.35 Irganox 3114 0.3 0.3 0.3 0.6 0.30.3 DSTDP 0.3 0.3 0.3 0.3 0.30.3 Et Zimate -- -- -- -- 0.10.1 30 (db),o 4 5 2 5 5 5 (db),d 4 4 2 5 5 5 (db)SUWY 4 5 3 3 3 4 Weatherability 5 5 5 5 2 2 35 Examples 38 and 39 contain ingTinuvin 328 and Irganox 3114 ave superior yellowness h response but poor weatherab ility especially Ethyl when Zimate is present. The introduction of HALS

Tinuvin 144 improv es weatherability butwith 40 adverse effect on yellowing performance(Examples 40-42, 45, 47, 49) . The addition DSTDP
of to the stabilizer system gives some improvement in yellowing performance (Example 45 vs f~:xample 42).
However a better balance in yellowing performance and weatherability is achieved with tree system containing Cyasorb W3346 (Examples 49:, 46 and 48).
While weatherability is decreased by t:he Ethyl Zimate of Example 50, the composition is of value for indoor applications particularly where it may come in contact with hindered phenolic: antioxidants such as Ionol capable of generating highly colored chromophores.

Claims (38)

The embodiments of the invention in which exclusive property or privilege is claimed are defined as follows:
1. A stabilizer system for styrene polymers consisting essentially of (a) a benzotriazole; (b) an oligomeric condensate of N,N'-(2,2,6,6-tetramethylpiperidyl) hexamethylene diamine and 2,4-dichloro-6-morpholino-1,3,5-s-triazine; and (c) tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate with the proviso that the stabilizer system does not contain phosphites or phosphonites stabilizers.
2. The stabilizer system of claim 1 comprising (a) from about 20 to about 70 parts by weight of the benzotriazole; (b) from about 18 to about 60 parts by weight of the oligomeric condensate; and (c) from about 12 to about 50 parts by weight of the tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate.
3. The stabilizer system of claim 1 wherein the benzotriazole is selected from the group consisting of:
2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)-benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2-(2'-hydroxy-5'-tert-amylphenyl) benzotriazole, and 2-(2'hydroxy-5'-tert-octylphenyl) benzotriazole.
4. The stabilizer system of claim 1 wherein the benzotriazole is 2-(2'-hydroxy-3',5'-di-tert-amylphenyl) benzotriazole.
5. The stabilizer system of claim 1 additionally containing a thiodipropionate.
6. The stabilizer system of claim 2 additionally containing from about 12 to about 40 parts by weight of a thiodipropionate.
7. The stabilizer system of claim 3 additionally containing a dialkyl thiodipropionate of a C12-C18 alkanol.
8. The stabilizer system of claim 5 additionally containing a zinc dialkyldithiocarbamate wherein the alkyl groups are C1-C8 alkyls.
9. A styrenic polymer stabilized with the stabilizer system of claim 1.
10. A styrenic polymer stabilized with the stabilizer system of claim 2.
11. A styrenic polymer stabilized with the stabilizer system of claim 3.
12. A styrenic polymer stabilized with the stabilizer system of claim 4.
13. A styrenic polymer stabilized with the stabilizer system of claim 5.
14. A styrenic polymer stabilized with the stabilizer system of claim 6.
15. A styrenic polymer stabilized with the stabilizer system of claim 7.
16. A styrenic polymer stabilized with the stabilizer system of claim 8.
17. The styrenic polymer of claim 9 selected from the group consisting of polystyrene, styrene-acrylonitrile copolymer, .alpha.-methylstyrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-butadiene-.alpha.-methylstyrene copolymer, acrylonitrile-styrene-(C3-C10 alkyl acrylate) copolymer, methacrylate-butadiene-styrene copolymer, styrene-methyl methacrylate copolymer, polystyrene blended with a polybutadiene to which styrene has been grafted, styrene-acrylonitrile copolymer blended with a poly(C3-C10 alkyl acrylate) rubber grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with a polybutadiene rubber grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with an ethylene-propylene-diene copolymer rubber grafted with a styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer blended with a poly(C3-C10 alkyl acrylate) rubber grafted with a styrene-methyl methacrylate copolymer, styrene-methyl methacrylate copolymer blended with a polybutadiene grafted with a styrene-methyl methacrylate copolymer and styrene-methyl methacrylate copolymer blended with an ethylene-propylene-diene rubber grafted with a styrene methyl methacrylate copolymer.
18. The styrenic polymer of claim 9 wherein the styrenic polymer is selected from the group consisting of styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer blended with a polybutadiene grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with a poly(C3 to C10 alkyl acrylate) rubber grafted with a styrene-acrylonitrile copolymer and styrene-acrylonitrile copolymer blended with an ethylene-propylene-diene copolymer rubber grafted with a styrene-acrylonitrile copolymer.
19. A stabilizer system for styrene polymers consisting essentially of (a) a benzotriazole; (b) a hindered amine light stabilizer selected from the group consisting of (i) bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; and (ii) bis-(1,2,2,6,6-pentamethyl-4-piperdinyl) ester of (3,5-di-tert-butyl-4-hydroxybenzyl)-butyl malonate; and (c) tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate with the proviso that the stabilizer system does not contain phosphites or phosphonites stabilizers.
20. The stabilizer system of claim 19 wherein the hindered amine light stabilizer is bis-(1,2,2,6,6-pentamethyl-4-piperdinyl) ester of (3,5-di-tert-butyl-4-hydroxybenzyl)-butyl malonate.
21. The stabilizer system of claim 19 wherein the hindered amine light stabilizer is bis-(2,2,6,6-tetramethyl-4-piperdinyl) sebacate.
22. The stabilizer system of claim 19 comprising (a) from about 20 to about 70 parts by weight of the benzotriazole; (b) from about 18 to about 60 parts by weight of the hindered amine light stabilizer; and (c) from about 12 to about 50 parts by weight of the hydroxybenzylisocyanurate.
23. The stabilizer system of claim 19 wherein the benzotriazole is selected from the group consisting of: 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)-benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2-(2'hydroxy-5'-tert-amylphenyl) benzotriazole, and 2-(2'-hydroxyl-5'-tertoctylphenyl) benzotriazole.
24. The stabilizer system of claim 19 wherein the benzotriazole is 2-(2'-hydroxy-3',5'-di-tert-amylphenyl) benzotriazole.
25. The stabilizer system of claim 19 additionally containing a thiodipropionate.
26. The stabilizer system of claim 20 additionally containing from about 12 to about 40 parts by weight of a thiodipropionate.
27. The stabilizer system of claim 21 additionally containing a dialkyl thiodipropionate of a C12-C18 alkanol.
28. The stabilizer system of claim 23 additionally containing a zinc dialkyldithiocarbamate wherein the alkyl groups are C1-C8 alkyls.
29. A styrenic polymer stabilized with the stabilizer system of claim 19.
30. A styrenic polymer stabilized with the stabilizer system of claim 20.
31. A styrenic polymer stabilized with the stabilizer system of claim 21.
32. A styrenic polymer stabilized with the stabilizer system of claim 22.
33. A styrenic polymer stabilized with the stabilizer system of claim 23.
34. A styrenic polymer stabilized with the stabilizer system of claim 24.
35. A styrenic polymer stabilized with the stabilizer system of claim 25.
36. A styrenic polymer stabilized with the stabilizer system of claim 26.
37. The styrenic polymer of claim 29 selected from the group consisting of polystyrene, styrene-acrylonitrile copolymer, .alpha.-methylstyrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-butadiene-.alpha.-methylstyrene copolymer, acrylonitrile-styrene-(C3-C10 alkyl acrylate) copolymer, methacrylate-butadiene-styrene copolymer, styrene-methyl methacrylate copolymer, polystyrene blended with a polybutadiene to which styrene has been grafted, styrene-acrylonitrile copolymer blended with a poly(C3 to C10 alkyl acrylate) rubber grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with a polybutadiene rubber grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with an ethylene-propylene-diene copolymer rubber grafted with a styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer blended with a poly(C3 to C10 alkyl acrylate) rubber grafted with a styrene-methyl methacrylate copolymer, styrene-methyl methacrylate copolymer blended with a polybutadiene grafted with a styrene-methyl methacrylate copolymer and styrene-methyl methacrylate copolymer blended with an ethylene-propylene-diene rubber grafted with a styrene methyl methacrylate copolymer.
38. The styrenic polymer of claim 29 wherein the styrenic polymer is selected from the group consisting of styrene-acrylonirile copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer blended with a polybutadiene grafted with a styrene-acrylonitrile copolymer, styrene-acrylonitrile copolymer blended with a poly(C3 to C10 alkyl acrylate) rubber grafted with a styrene-acrylonitrile copolymer and styrene-acrylonitrile copolymer blended with an ethylenepropylene-diene copolymer rubber grafted with a styrene-acrylonitrile copolymer.
CA002177737A 1993-12-02 1994-12-02 Stabilizer system for non yellowing polymer composition Expired - Fee Related CA2177737C (en)

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US16013893A 1993-12-02 1993-12-02
US08/160,138 1993-12-02
PCT/US1994/013801 WO1995015358A1 (en) 1993-12-02 1994-12-02 Stabilizer system for non yellowing polymer composition

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