Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1987-11-02
1989-10-03
Lilling, Herbert J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524518, 524519, 524505, 524525, 525 89, 525 95, 525193, 525211, C08K 316, C08K 501, C08K 514, C08L 906
Patent
active
048717967
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Compounds consisting of polyolefin and a partially crosslinked rubber phase possess good properties as thermoplastic elastomers (TPEs) such as heat resistance, mechanical strength, flexibility and elasticity etc., but their flowability is poorer than generally used thermoplastics, leading to problems such as flow marks in the manufacture of large molded parts. In order to resolve these problems, for example, partially crosslinked compounds of polyolefin and two rubber components (Japanese Pat. No. 54-23702), partially crosslinked compounds in which polyolefin is blended with a composition of a polyolefin and a rubber component which was treated in the presence of organic peroxide (Japanese Pat. No. 56-15743) as well a the method of manufacture of such compounds (No. 56-15740) have been proposed.
These inventors have developed compounds in which a polyolefin is added to a composition consisting of halobutyl-containing rubber phase which is partially crosslinked with a polyolefin, using metal oxide (MOx) and/or metal chlorides (MCl) as vulcanizing agents. In addition, the method of manufacture of TPE compositions including styrenic rubber has been proposed, for example Japanese Patent Appl. No. 59-6236 proposes manufacture of compositions containing a hydrogenated styrene-conjugated diene block copolymer, softening agents, olefinic resins, peroxide-curable olefinic rubber, an uncrosslinked hydrocarbon rubber and inorganic fillers, in which the peroxide-curable rubber is partially crosslinked.
Although the above-mentioned compositions possess good properties as thermoplastic elastomers (TPEs), in comparison to polyurethane (PU) type elastomers they suffer from inadequate high temperature physical properties and inadequate gloss for a high quality appearance. The present invention prevents the decrease in stiffness with increased temperature and improves the gloss of molded parts for a high quality appearance, without loss in the properties of olefinic TPEs.
SUMMARY OF THE INVENTION
A method of producing compounds in which the rubber phase contains a polyolefin and a halobutyl rubber, which is partially crosslinked, to which composition is then added additional polyolefin and a vulcanizable olefinic rubber, which is then further crosslinked using organic peroxides, and then blended with a styrenic rubber. The TPE compounds incorporate (A) polypropylene 10-90 weight parts (wt. pts.), (B) halobutyl rubber 90-10 wt. pts. (where (A)+(B)=100), (C) an olefinic rubber 10-120 wt. pts., (D) mineral oil softener 5-120 wt. pts., which are then treated thermally in the presence of (E) MOx and/or MCl, to which composition of 100 weight parts is added (F) polyolefin 100-600 wt. pts., and (G) a vulcanizable olefinic rubber 50-500 wt. pts. The resulting blend is then thermally treated with (H) organic peroxide(s), to which blend of 100 wt. pts. is then added and uniformly dispersed (I) 5-150 wt. pts. of styrenic rubber.
DETAILED DESCRIPTION
(A) Polypropylene (PP)
PP suitable for use in this invention includes homopolymer or copolymer with ethylene, 1-butene, 1-pentene, 1-hexene or 4-methylpentene or other alpha-olefins with propylene as the main component, including random or block copolymers. Melt flow rate (MFR) is about 0.3-60 g/10 min, preferably 1-40, most preferably 3-30. Component A of the composition has the highest melting point of polyolefins, and imparts heat resistance and improved mechanical properties to the compound.
(B) Halobutyl Rubber
For purposes of this invention halobutyl rubber means halogenated butyl rubber. The halogen can be chlorine or bromine, usual content is 0.5-4.0 wt %. It is preferable that this component has a Mooney Viscosity, ML1+8 (100.degree. C.) of about 30-100 and 0.5-4.0 mol % unsaturation. Halobutyl rubber can be crosslinked using MOx and/or MCl, and exists as a dispersed crosslinked rubber phase, imparting abrasion resistance, impermeability and "anti-slip properties" to the compound.
(C) Olefinic Rubber
Rubber in which two to more of: ethylene, prop
REFERENCES:
patent: 4212787 (1980-07-01), Matsuda et al.
patent: 4220579 (1980-09-01), Rinehart
patent: 4481323 (1984-11-01), Sterling
patent: 4593062 (1986-06-01), Puydak et al.
patent: 4607074 (1986-08-01), Hazelton et al.
Derwent Abs. 80-49015c/28, Mitsui Petro (J55071739) 5-80.
Baba Isao
Komatsu Masato
Yamamoto Noboru
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