GB1560896A

GB1560896A - Selectively hydrogenated diene block copolymer compositions

Info

Publication number: GB1560896A
Application number: GB44427/76A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1975-10-28
Filing date: 1976-10-26
Publication date: 1980-02-13
Also published as: DE2648452C2; ZA766398B; SE7611890L; FR2329708A1; FR2329708B1; DE2648452A1; AU500861B2; SE411913B; NL183093B; AU1900276A; ES452730A1; JPS5253957A; BE847613A; NL7611829A; IT1069029B; CA1083283A; NL183093C; JPS5931540B2

Description

(54) SELECTIVELY HYDROGENATED DIENE BLOCK COPOLYMER COMPOSITIONS (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V., a company organised under the laws of The Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a composition comprising a selectively hydrogenated block copolymer. It also relates to shaped articles which are obtained by using such composition.

It is known that selectively hydrogenated block copolymers having at least two polymer blocks of a mono-alkenyl or mono-alkenylidene aromatic hydrocarbon and at least one partially or completely hydrogenated polymer block of an aliphatic conjugated diene hydrocarbon have certain advantages. However, their pro cess ability leaves something to be desired. It may be improved by extending the block copolymers with certain olefinic polymers. Furthermore, the blends may be extended with rubber extending oils in order to both improve processability and reduce the cost of the final composition. However, the resulting compositions show bleed-out of oil following exposure to actinic radiation.

Oil bleed-out appears to occur with the compositions comprising a selectively hydrogenated block copolymer, a polyolefin and oil after injection moulding operation which unavoidably results in surface stresses. No adverse phenomena occur during the initial period. Eventually, a thin film of oil, which is largely identical with the extending oil, exudes to the surface and forms a tacky surface film which gradually thickens under continued ageing or exposure to light. Upon still further exposure, the oil appears to be absorbed into the shaped article. It would be recognized by experts in the Art, that even a temporary presence of an oily surface could result in a substantial technical disadvantage. The presence of the oil not only is unsightly, but causes difficulty with adhesion to substrates or to paint films.

The object of the invention is to reduce or to eliminate oil bleed-out from oilextended compositions comprising a selectively hydrogenated block copolymer and a polyolefin.

It has been found that oil bleed-out is minimized or prevented by the presence of sterically hindered phenols and benzotriazoles.

Now, in accordance with the invention a composition is provided comprising (a) 100 parts by weight of a selectively hydrogenated block copolymer having at least two polymer blocks A of a mono-alkenyl or mono-alkenylidene aromatic hydrocarbon and at least one partially or completely hydrogenated polymer block B of an aliphatic conjugated diene hydrocarbon; (b) 5-150 parts by weight of an olefin polymer; (c) 10-175 parts by weight of a rubber extending oil; and (d) 0.2-5 parts by weight of a sterically hindered phenol as hereinafter defined, a 2-(hydroxyphenyl)-benzotriazole derivative or a mixture thereof.

The selectively hydrogenated block copolymer present in the composition according to the invention may have a linear, branched or radial structure. It may be produced by sequential block polymerization utilizing a lithium initiator such as a lithium alkyl. Alternatively, a coupling agent may be used in the production of the block copolymer resulting in either a linear or a branched or radial product. The resulting block copolymer is then selectively hydrogenated.

Each polymer block A formed from a mono-alkenyl or a mono-alkenylidene aromatic hydrocarbon may have a number average molecular weight between 7,500 and 50,000. The polymer block B formed from an aliphatic conjugated diene hydrocarbon may have a number average molecular weight between 10,000 and 125,000. At least 90% of the residual aliphatic double bonds of the diene polymer block B may be hydrogenated. Preferably at least 98% of these double bonds are hydrogenated.

The polymer blocks A may be formed from styrene, alpha-methyl styrene or alpha tert-butyl styrene. The polymer block B may be formed from butadiene or isoprene. The block copolymer may have the linear structure polystyrene-polybutadienepolystyrene or polystyrene-polyisoprene-polystyrene.

As used herein the term "a sterically hindered phenol" denotes a phenol of the formula:

wherein each R individually represents a hydrogen atom, an alkyl group having from 1-20 carbon atoms of a phenalkyl group of the formula

wherein R1 is an alkylene group having from 1 to 3 carbon atoms in the linear chain and a total of from 1 to 8 carbon atoms in the group and each R individually represents a hydrogen atom or an alkyl group having from 1--20 carbon atoms provided that in formula I above at least one R ortho to the OH-group is an alkyl group, and not more than one R group is a phenalkyl group of formula II.

Examples of these phenols are: 2-methylphenol 2,6-ditert.-butylEmethylphenol 2-methyl-6-isopropylphenol 2-tert.-butyl4-methylphenol 2-amylphenol 2-nonylphenol 2-dodecylphenol 2-tetradecylphenol bis-(2,6-ditert.-butyl-3-hydroxyphenyl)methane 2,2-bis(2-hydroxyphenyl)propane 2-eicosylphenol 2,4,6-trieicosylphenol 1,3-bis(2-hydroxyphenyl)-2-methyl-2-t-butylpropane and mixtures of these phenols.

Preferred hindered phenols include methylene bisphenols having the general configuration.

wherein R' and R2 are alkyl radicals having 2-5 carbon atoms each. The preferred species is 2,2'-methylene bis(;ethyl-6-tert.-butylphenol).

The benzotriazole which may be present in the composition according to the invention is preferably a benzotriazole which has the general formula

wherein Rl is an alkyl radical having from one-six carbon atoms and R2 is an alkyl radical having from one-six carbon atoms or hydrogen. Examples are: 2(2-hydroxy-3,5i-n-hexylphenyl)benzottiazole 2(2-hydroxy-5-methylphenyl)benzotriazole 2(2-hydroxy-5-tert-butylphenyl)benzotriazole 2-(2-hydroxy-3 -methyl-5-isoamylphenyl)benzotriazole 2(2-hydroxy-3 -hexyl-5-isopropylphenyl)benzotriazole 2(2-hydroxy-3,5 < 1imexhylphenyl)benzotriazole.

In a specific embodiment 2-(2-hydroxy-5-methylphenyl)benzotriazole produced outstanding results.

Preferred benzotriazoles are chlorinated and have the general formula

wherein R3 and Rs are alkyl radicals having from 2-5 carbon atoms each. The preferred species is 2-(3',5'-ditert.-butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole.

The sterically hindered phenols and benzotriazoles are preferably present in an amount of 0.75-2 parts by weight per 100 parts by weight of the block copolymers.

The rubber extending oil which is present in the composition according to the invention may be a hydrocarbon oil which may be paraffinic, naphthenic, or aromatic, and relatively nonvolatile, at least under the physical conditions to which the composition would normally be exposed. It is preferably present in an amount of 50-125 parts by weight per 100 parts by weight of the block copolymer.

The olefin polymer which is present in the composition according to the invention may be a homopolymer such as polyethylene and polypropylene or a copolymer which may be a tapered, random or block copolymer.

The olefin polymer is preferably present in an amount of 10-125 parts by weight per 100 parts by weight of the block copolymer.

A preferred composition comprises the following: a) a block copolymer having the configuration polystyrene-completely hydrogen ated polybutadiene-polystyrene b) Polypropylene c) Mineral rubber extending oil d) 2,2'-methylene bis [4-ethyl-6-tert.-butylphenol] and e) 2-(3',5'-ditert.-butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole.

It is emphasized that the present invention relates to compositions comprising at least the three conventional essential components including the selectively hydrogenated block copolymer, together with the oil bleed-out reducing agent. Since the diene blocks have been at least partially hydrogenated, the normal stability problems encountered with non-hydrogenated diene polymers are at a minimum. Thus, normal oxygen, ozone and light sensitivity in the bulk properties (tensile strength, viscosity and melt flow) are of little concern in the hydrogenated block copolymers. On the other hand, the oil bleed-out problem has been found to be of major concern in the utility of the hydrogenated block copolymer compounds, but it does not affect the utility, to any appreciable extent, of compositions comprising the non-hydrogenated block copolymers.

Other compounding ingredients may be present, such as resins, fillers, pigment and stabilizers. The ingredients may be mixed by dry blending procedures, or in a typical Banbury mixing operation and the mixture so formed is then subjected to shaping operation such as compression moulding or some form of extrusion moulding.

The invention is illustrated in the following Examples.

EXAMPLE 1 The basic composition used in this Example was as follows: Block copolymer 100 parts by weight Polypropylene 40 " " " Penrico EX263 extending Oil 150 The block copolymer had the structure polystyrenecompletely hydrogenated polybutadiene-polystyrene with block molecular weight of 25,000-100,000-25,000.

Plaques measuring 10 cox 10 cmx 0.16 cm were injection moulded and exposed to GE Sunlamps in equipment resembling that required in the Fadeometer test, ASTM 0928 Method B until maximum oil bleed-out occurred. For these tests, samples of the basic composition were modified with one or more of additives according to the invention, or with other additives for comparative purposes, and the changes in maximum oil bleed-out noted below: TABLE 1 Parts by Weight Sample A B C D E Additive; Tetrakis [methylene 3-(3',5'-di tert.butyl-4'-hydroxyphenyl) propionateimethane 1.0 1.0 Dilaurylthiodipropionate 1.72 1.0 2,2'-bis(4-methyl-6-tert.

butylhydroxyphenyl)methane 0.58 2(3',5 '-di-tert.butyl-2'-hydroxy phenyl)-5-chlorobenzotriazole 1.22 Max. Oil Bleed-Out, mg/6.45 CIII 1.2 1.5 2.1 0.6 1.0 Samples A, B and C were comparative samples, whilst Samples D and E were according to this invention. The amount of oil bleed-out was determined by weighing the plaque, blotting off the oil from the surface with paper and re-weighing the sample to determine weight loss due to oil removal.

EXAMPLE 2 A second series of samples were prepared wherein the basic composition used in Example 1 was modified with 180 parts of calcium carbonate and 2 parts by weight of a polyepoxide. Injection moulded plaques of the above dimensions were formed containing various additives, and the samples were exposed to a fluorescent UV source and maximum oil bleed-out was determined as described in Example 1. Table 2 lists additives used and the results obtained.

TABLE 2 Parts by Weight Sample F G H I Tetrakis [methylene 3-(3',5'di-tert.

butyl4'-aydroxyphenyl)- propionate]methane 0.5 Dilaurylthiodipropionate 0.5 2,2'-bis(4-methyl-6-tert.-butyl- hydroxyphenyl)methane 1.0 1.0 2(3 ',5'Ai-tert.butyl-2'-hydroxy- phenyl)-5-chloro-benzotriazole 1.0 1.0 Max. Oil Bleed-out, mg/6.45 cm2 1.8 0.2 0.1 0.0 Sample F was a comparative sample, whilst samples G, H, and I were according to this invention.

WHAT WE CLAIM IS:- 1. A composition which comprises: (a) 100 parts by weight of a selectively hydrogenated block copolymer having at least two polymer blocks A of a mono-alkenyl or mono-alkenylidene aromatic hydrocarbon and at least one partially or completely hydrogenated polymer block B of an aliphatic conjugated diene hydrocarbon; (b) 5-150 parts by weight of an olefin polymer; (c) 10-175 parts by weight of a rubber extending oil; and (d) 0.2-5 parts by weight of a sterically hindered phenol as hereinbefore defined, a 2-(hydroxyphenyl)-benzotriazole derivative or a mixture thereof.

2. A composition as claimed in claim 1, wherein the selectively hydrogenated block copolymer has at least two polymer blocks A, each having a number average molecular weight between 7,500 and 50,000, and at least one polymer block B having a number average molecular weight between 10,000 and 125,000.

3. A composition as claimed in claim 1 or 2, wherein at least 98% of the residual aliphatic double bonds of the diene polymer block B are hydrogenated.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. to GE Sunlamps in equipment resembling that required in the Fadeometer test, ASTM 0928 Method B until maximum oil bleed-out occurred. For these tests, samples of the basic composition were modified with one or more of additives according to the invention, or with other additives for comparative purposes, and the changes in maximum oil bleed-out noted below: TABLE 1 Parts by Weight Sample A B C D E Additive; Tetrakis [methylene 3-(3',5'-di tert.butyl-4'-hydroxyphenyl) propionateimethane 1.0 1.0 Dilaurylthiodipropionate 1.72 1.0 2,2'-bis(4-methyl-6-tert. butylhydroxyphenyl)methane 0.58 2(3',5 '-di-tert.butyl-2'-hydroxy phenyl)-5-chlorobenzotriazole 1.22 Max. Oil Bleed-Out, mg/6.45 CIII 1.2 1.5 2.1 0.6 1.0 Samples A, B and C were comparative samples, whilst Samples D and E were according to this invention. The amount of oil bleed-out was determined by weighing the plaque, blotting off the oil from the surface with paper and re-weighing the sample to determine weight loss due to oil removal. EXAMPLE 2 A second series of samples were prepared wherein the basic composition used in Example 1 was modified with 180 parts of calcium carbonate and 2 parts by weight of a polyepoxide. Injection moulded plaques of the above dimensions were formed containing various additives, and the samples were exposed to a fluorescent UV source and maximum oil bleed-out was determined as described in Example 1. Table 2 lists additives used and the results obtained. TABLE 2 Parts by Weight Sample F G H I Tetrakis [methylene 3-(3',5'di-tert. butyl4'-aydroxyphenyl)- propionate]methane 0.5 Dilaurylthiodipropionate 0.5 2,2'-bis(4-methyl-6-tert.-butyl- hydroxyphenyl)methane 1.0 1.0 2(3 ',5'Ai-tert.butyl-2'-hydroxy- phenyl)-5-chloro-benzotriazole 1.0 1.0 Max. Oil Bleed-out, mg/6.45 cm2 1.8 0.2 0.1 0.0 Sample F was a comparative sample, whilst samples G, H, and I were according to this invention. WHAT WE CLAIM IS:-

1. A composition which comprises: (a) 100 parts by weight of a selectively hydrogenated block copolymer having at least two polymer blocks A of a mono-alkenyl or mono-alkenylidene aromatic hydrocarbon and at least one partially or completely hydrogenated polymer block B of an aliphatic conjugated diene hydrocarbon; (b) 5-150 parts by weight of an olefin polymer; (c) 10-175 parts by weight of a rubber extending oil; and (d) 0.2-5 parts by weight of a sterically hindered phenol as hereinbefore defined, a 2-(hydroxyphenyl)-benzotriazole derivative or a mixture thereof.

4. A composition as claimed in claim 1, 2 or 3, wherein the sterically hindered

phenol is a methylene bisphenol having the general formula

wherein R1 and R2 are alkyl radicals having 2-5 carbon atoms each.

5. A composition as claimed in any one of claims 14, wherein the benzotriazole derivative is one having the general formula

wherein R, is an alkyl radical having from 1 to 6 carbon atoms, and R2 is an alkyl radical having from 1 to 6 carbon atoms or hydrogen.

6. A composition as claimed in any one of claims 1S, wherein the benzotriazole derivative is a chlorinated one having the general formula

wherein R, and RJ are alkyl radicals having from 2 to 5 carbon atoms each.

7. A composition as claimed in any one of the preceding claims, wherein the component (d) is present in an amount of 0.75-2 parts by weight per 100 parts by weight of the block copolymer.

8. A composition as claimed in any one of the preceding claims, wherein the rubber extending oil is a hydrocarbon oil.

9. A composition as claimed in any one of the preceding claims, wherein the rubber extending oil is present in an amount of 50-125 parts by weight per 100 parts by weight of the block copolymer.

10. A composition as claimed in any one of the preceding claims, wherein the olefin polymer is present in an amount of 10-125 parts by weight per 100 parts by weight of the block copolymer.

11. A composition as claimed in any one of the preceding claims, substantially as hereinbefore described.

12. Shaped articles whenever obtained from a composition as claimed in any one of the preceding claims.