Rubber composition, and foamed rubber product using the same
The present invention discloses a rubber composition, a processing method thereof, and a foamed rubber product produced by the rubber composition and a production method thereof. The rubber composition comprises a rubber matrix and essential components, wherein, based on 100 parts by weight of the rubber matrix, the rubber matrix comprises a branched polyethylene with a content represented as A, in which 0<A≤100 parts; and an EPM and an EPDM with a total content represented as B, in which 0≤B<100 parts, and the essential components comprises 0.5-10 parts of a crosslinking agent, and 1.5-25 parts of a foaming agent. The rubber composition is useful in the production of sponge seal strip, foamed rubber compound of high expansion ratio, shock absorbing foamed rubber sheet, light-colored high-strength foamed sheet, foam-solid composite seal strip, and solid cycle tires internally filled with foamed elastomer. The branched polyethylene replaces a part or all of the ethylene-propylene rubber in the foaming rubber composition, which can increase the melt strength, the foamability and particularly the pre-foamability of the rubber composition, and make the rubber product has a lower compression set.
1 . A rubber composition, comprising a rubber matrix and essential components, wherein, based on 100 parts by weight of the rubber matrix, the rubber matrix comprises a branched polyethylene with a content represented as A, in which 10≤A<100 parts, and an ethylene-propylene monomer (EPM) and an ethylene-propylene-diene monomer (EPDM) with a total content represented as B, in which 0<B≤90 parts; and based on 100 parts by weight of the rubber matrix, the essential components comprises 0.5-10 parts of a crosslinking agent, and 1.5-25 parts of a foaming agent,
wherein, the branched polyethylene comprises an ethylene homopolymer having:
a degree of branching of from 60 to 70 branches/1000 carbon atoms,
a secondary branch structure,
a methyl branch content of from 66.5 to 68.1 mol %,
an ethyl branch content of from 7.1 to 7.2 mol %,
a propyl branch content of from 4.2 to 4.6 mol %,
a butyl branch content of from 2.7 to 3.2 mol %,
a pentyl branch content of from 2.8 to 3.2 mol %,
a weight average molecular weight of from 436,000 to 518,000, and
a Mooney viscosity ML (1+4) at 125° C. of from 93 to 102,
wherein the branched polyethylene is obtained by catalytic homopolymerization of ethylene in the presence of an α-diimine nickel catalyst.
2 . The rubber composition according to claim 1 , wherein the crosslinking agent comprises at least one of a peroxide crosslinking agent and sulfur, wherein the peroxide crosslinking agent comprises at least one of di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexyne-3, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(benzoylperoxy) hexane, tert-butyl peroxybenzoate, and tert-butylperoxy-2-ethylhexyl carbonate.
3 . The rubber composition according to claim 1 , wherein the foaming agent comprises at least one of sodium bicarbonate, azodicarbonamide (AC), dinitrosopentylenetetramine (H), 4,4′-oxydibenzenesulfonyl hydrazide (OBSH), benzenesulfonyl hydrazide (BSH), urea, and a low-boiling point hydrocarbon foaming agent in the form of microcapsules.
4 . The rubber composition according to claim 1 , further comprising auxiliary components, which comprise, based on 100 parts by weight of the rubber matrix, 0.2 to 10 parts of an assistant crosslinking agent, 30 to 200 parts of a reinforcing filler, 10 to 100 parts of a plasticizer, 1 to 3 parts of a stabilizer, 2 to 20 parts of a metal oxide, 3 to 7 parts of a silane coupling agent, 1 to 5 parts of polyethylene glycol, 0.5 to 3 parts of stearic acid and 0 to 3 parts of a vulcanization accelerator.
5 . The rubber composition according to claim 4 , where the silane coupling agent comprises at least one of vinyl tris(2-methoxyethoxy) silane (A-172), γ-glycidoxypropyltrimethoxysilane (A-187) and γ-mercaptopropyltrimethoxysilane (A-189); the stabilizer comprises at least one of 2,2,4-trimethyl-1,2-dihydroquinoline polymer (RD), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), and 2-mercaptobenzimidazole (MB); the assistant crosslinking agent comprises at least one of triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triallyl trimellitate, trimethylolpropane trimethacrylate, N,N′-m-phenylene bismaleimide, N,N′-bis(furfurylidene) acetone, 1,2-polybutadiene, a metal salt of an unsaturated carboxylic acid, and sulfur; the plasticizer comprises at least one of pine tar, motor oil, naphthenic oil, paraffin oil, coumarone, RX-80, vaseline, and paraffin; the metal oxide comprises at least one of zinc oxide, magnesia, and calcium oxide; the reinforcing filler comprises at least one of carbon black, silica, calcium carbonate, talc, calcined clay, magnesium silicate, and magnesium carbonate; the vulcanization accelerator comprises at least one of 2-mercaptobenzothiazole, dibenzothiazyl disulfide, tetramethyl thiuram monosulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, N,N-dicyclohexyl-2-benzothiazole sulfenamide, bismaleimide, and ethylene thiourea.
6 . A solid cycle tire internally filled with a foamed elastomer, wherein, the rubber compound used for the internally filled foamed elastomer comprises said rubber composition according to claim 1 .
7 . A foamed rubber product, wherein, the rubber compound used for said foamed rubber product comprises said rubber composition according to claim 1 .
8 . The foamed rubber product according to claim 7 , wherein, said foamed rubber product is a sponge seal strip, wherein, the rubber compound used for said sponge seal strip comprises said rubber composition.
9 . The foamed rubber product according to claim 7 , wherein, said foamed rubber product is a shock-absorbing foamed rubber sheet, wherein the rubber compound used comprises said rubber composition.
10 . The foamed rubber product according to claim 7 , wherein, said foamed rubber product is a foam-solid composite seal strip, wherein the rubber compound used in the formed portion of the foam-solid composite seal strip comprises said rubber composition.
11 . A rubber composition, comprising a rubber matrix and essential components, wherein, based on 100 parts by weight of the rubber matrix, the rubber matrix comprises:
a branched polyethylene with a content represented as A, in which 10≤A≤100 parts, and,
optionally, an ethylene-propylene monomer (EPM) and an ethylene-propylene-diene monomer (EPDM) with a total content represented as B, in which 0≤B≤90 parts;
wherein, based on 100 parts by weight of the rubber matrix, the essential components comprises 0.5-10 parts of a crosslinking agent and 1.5-25 parts of a foaming agent;
wherein, the branched polyethylene comprises an ethylene homopolymer having:
a degree of branching of from 60 to 70 branches/1000 carbon atoms;
a secondary branch structure;
a methyl branch content of from 66.5 to 68.1 mol %;
an ethyl branch content of from 7.1 to 7.2 mol %;
a propyl branch content of from 4.2 to 4.6 mol %;
a butyl branch content of from 2.7 to 3.2 mol %;
a pentyl branch content of from 2.8 to 3.2 mol %;
a weight average molecular weight of from 436,000 to 518,000; and
a Mooney viscosity ML (1+4) at 125° C. of from 93 to 102; and
wherein the branched polyethylene is obtained by catalytic homopolymerization of ethylene in the presence of an α-diimine nickel catalyst.