JPH06299001A - Rubber composition for shape - Google Patents

Abstract

PURPOSE:To improve freeze resistance, heat resistance, kneadability, rollability and mold releasability by incorporating an organic peroxide in a hydrogenated random diene copolymer prepared from a specific conjugated diene and an aromatic vinyl compound. CONSTITUTION:A random diene copolymer is prepared from a conjugated diene, which has a weight-average molecular weight of 5,000-1,000,000, a molecular weight distribution Mw/Mn of 10 or less, an aromatic vinyl compound bond content of 5-50wt.% and an vinyl bond content in the diene portion of 10% or more, and an aromatic vinyl compound. The random diene copolymer is dissolved in a hydrocarbon solvent and hydrogenated at 20-150 deg.C under a hydrogen pressure of 1-100kg/cm<2> in the presence of the catalyst to hydrogenate at least 80% of the olefinic bonds of the copolymer, thereby preparing a hydrogenated diene polymer. The rubber composition for shape is obtained by incorporating 0.1-10pt.wt organic peroxide in 100 pts.wt. hydrogenated diene polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for molds, which has excellent cold resistance and heat resistance, good roll processability, and excellent mold releasability.

[0002]

2. Description of the Related Art Sealing materials, gaskets, and packings have changed from natural rubber to styrene-butadiene rubber (SBR) and ethylene-propylene-diene copolymer rubber (EPDM) as rubber materials due to increasing heat resistance. I'm doing it. On the other hand, the vulcanizing agent for cross-linking these rubbers has been changed from sulfur vulcanization system to organic peroxide. At present, rubber products such as sealing materials, gaskets, packings, and the like, which are produced by combining ethylene-propylene-diene copolymer rubber (EPDM) and organic peroxide, have been produced in response to the above requirements. However, the combination of ethylene-propylene-diene copolymer rubber and organic peroxide is inferior in mold releasability during vulcanization molding, and therefore cracks or tears occur when the product is taken out from the mold,
Therefore, there is a drawback that a satisfactory product cannot be obtained and a defective molding rate is increased.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a rubber for molds which has excellent cold resistance and heat resistance, good kneading workability and roll workability, and excellent moldability and mold releasability. It is intended to provide a composition.

[0004]

The present invention is a random diene-based copolymer of at least one conjugated diene and a vinyl aromatic compound, having a molecular weight distribution Mw / Mn of 10 or less and containing a vinyl aromatic compound bond. 5 to 50% by weight,
A hydrogenated diene polymer in which at least 80% of the olefinic unsaturated bond of the polymer is hydrogenated by hydrogenating a diene copolymer having a vinyl bond content of 10% or more in the diene part The present invention provides a rubber composition for molds, which is used as a rubber component.

The hydrogenated diene-based polymer used in the present invention is a random diene-based copolymer of at least one conjugated diene and a vinyl aromatic compound and has a molecular weight distribution M.
A diene-based copolymer having a w / Mn of 10 or less, a vinyl aromatic compound bond content of 5 to 50% by weight, and a vinyl bond content of its diene portion of 10% or more is hydrogenated to give a polymer of the polymer. It is a hydrogenated diene polymer in which at least 80% of olefinic unsaturated bonds are hydrogenated.

Examples of the conjugated diene monomer include butadiene, isoprene, pentadiene and 2,3-dimethylbutadiene. Further, examples of the aromatic vinyl compound include styrene, paramethylstyrene, and α-methylstyrene.

In the microstructure of the diene polymer, the vinyl bond content of the conjugated diene side chain is 10% or more, preferably 20 to 80%, particularly preferably 20 to 50%. If it is less than 10%, the hydrogenated diene polymer of the present invention has a resinous property, and the object of the present invention cannot be achieved.

The content of the aromatic vinyl compound in the diene polymer is 5 to 50% by weight, preferably 15 to
35% by weight. If it is less than 5% by weight, the tensile strength is lowered. When it exceeds 50% by weight, the hydrogenated diene polymer of the present invention has a resinous property, and the object of the present invention cannot be achieved. The aromatic vinyl compound in the diene-based polymer is a random copolymer that is randomly bonded, and is a Corsov [I. M. Kolthoff, J. et al. Polymer S
ci. , Vol 1 p429 (1946)], the content of the block-shaped polyvinyl aromatic compound is 10% by weight or less, preferably 5% by weight or less in the total bound vinyl aromatic compound.

The molecular weight of the diene polymer is a weight average molecular weight, preferably 5,000 to 1,000,000,
More preferably, it is 30,000 to 300,000. When it is less than 5,000, the hydrogenated diene-based copolymer of the present invention does not become a rubber-like substance but becomes a liquid state, and it is 1,000,000.
If it exceeds, workability tends to decrease. The molecular weight distribution Mw / Mn of the polymer is 10 or less.

The diene polymer can be obtained, for example, by anionic living polymerization in a hydrocarbon solvent using an organolithium initiator. Further, the branched polymer can be obtained by adding a necessary amount of a trifunctional or higher functional coupling agent at the end of the polymerization to carry out a coupling reaction. 1,2-,
Ethers, tertiary amine compounds, alkoxides of alkali metals such as sodium and potassium, phenoxides, and sulfonates are used to control the amount of vinyl bonds such as 3,4-bonds. As the organolithium initiator, n-
Butyl lithium, sec-butyl lithium, tert-
Butyl lithium or the like is used. Hexane, heptane, methylcyclopentane, cyclohexane, benzene, toluene, xylene, 2-methylbutene-1,2-methylbutene-2 and the like are used as the hydrocarbon solvent.

Polymerization may be carried out batchwise or continuously,
The polymerization temperature is usually in the range of 0 to 120 ° C., the coupling agent is a trifunctional or higher functional coupling agent, and tetrachlorosilicon, butyltrichlorosilicon, tetrachlorotin, butyltrichlorotin, tetrachlorogermanium, bis (trichlorosyl) are used. Ethane, divinylbenzene, diethyl adipate, epoxidized liquid polybutadiene, epoxidized soybean oil, epoxidized linseed oil, tolylene diisocyanate, diphenylmethane diisocyanate, 1,2,
4-benzene triisocyanate etc. are mentioned. The hydrogenated diene polymer of the present invention can be obtained by hydrogenating the diene polymer thus polymerized.

The hydrogenation rate of the olefinic unsaturated bond of the hydrogenated diene polymer of the present invention is 80% or more, preferably 90% or more. When the hydrogenation rate is less than 80%, the effect of improving the weather resistance and heat resistance of the polymer is insufficient, which is not preferable. In the hydrogenation reaction, the above conjugated diene polymer is dissolved in a hydrocarbon solvent and the reaction is carried out at 20 to 150 ° C. for 1 to 100 ° C.
It is carried out in the presence of a catalyst under hydrogen under pressure of kg / cm ² .
As the hydrogenation catalyst, a catalyst in which a noble metal such as palladium, ruthenium, rhodium or platinum is supported on silica, carbon or diatomaceous earth, a complex catalyst such as rhodium, ruthenium or platinum, an organic carboxylic acid such as cobalt or nickel and an organic aluminum are used. Or a catalyst composed of organolithium,
Titanium compounds such as dicyclopentadienyl titanium dichloride, dicyclopentadienyl diphenyl titanium, dicyclopentadienyl titanium ditolyl, dicyclopentadienyl titanium dibenzyl and lithium, aluminum,
A hydrogenation catalyst composed of an organometallic compound composed of magnesium is used.

In the rubber composition for molds of the present invention, if necessary, the hydrogenated diene polymer is added to other diene rubbers such as styrene-butadiene rubber (SBR) and isoprene rubber (IR), and ethylene-α. -Olefin- (diene) -based rubber [EP (D) M], butyl rubber, acrylic rubber, epichlorohydrin-based rubber, halogenated polyethylene-based elastomer, and various commonly used compounding agents can be added.

As a compounding agent, if necessary, a filler,
Softener, plasticizer, activator, dispersant, foaming agent, foaming aid,
A lubricant, an antiaging agent, an anti-scorch agent, a peptizer, and other additives can be used in combination.

As the filler, inorganic fillers such as carbon black, white carbon (silicate compound), calcium carbonate, talc and clay; high styrene resin, coumarone indene resin, phenol resin, lignin, modified melamine resin, petroleum oil Organic fillers such as resins may be mentioned. Of these, an inorganic filler is particularly preferably used.

As the softening agent, petroleum softening agents such as process oil (aromatic type, naphthene type, paraffin type), lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum; coal tar, coal tar pitch, etc. Tar-based softeners; castor oil, linseed oil,
Fatty oil-based softeners such as rapeseed oil and coconut oil; waxes such as tall oil, sub, beeswax, corn wax, and laurin;
Ricinoleic acid, palmitic acid, barium stearate,
Fatty acids and fatty acid salts such as calcium stearate and zinc laurate; synthetic polymer parts such as petroleum resins.

As the plasticizer, a phthalic acid ester type,
Adipate-based, sebacate-based, phosphoric acid-based tackifiers such as coumarone indene resin,
As the colorant such as terpene / phenol resin and xylene / formalin resin, inorganic and organic pigments can be used.

Examples of the lubricant include aliphatic hydrocarbons such as paraffin wax, polyethylene wax and polypropylene wax, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid and behenic acid. Higher fatty acids or metal salts thereof, that is, lithium salt, calcium salt, sodium salt, magnesium salt, potassium salt,
Aliphatic alcohols such as palmityl alcohol, cetyl alcohol, stearyl alcohol, caproic acid amide, caprylic acid amide lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide and other aliphatic amides, fatty acids and alcohols Fluorine compounds such as esters, fluoroalkylcarboxylic acids or metal salts thereof, and fluoroalkylsulfonic acid metal salts can be mentioned.

As the antioxidant, aldol-α-naphthylamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. , Phenyl-β-naphthylamine, N-phenyl-N′-isopropyl-P
-Phenylenediamine, diphenylamine derivatives, 2-
Amine such as mercaptobenzimidazole zinc salt, nickel dibutyldithiocarbamate, aldehydes,
Amine, ketones, amines, imidazoles, dithiocarbamates and the like are preferably used, but 2,6-
It is also effective to use a phenolic antioxidant such as di-t-butyl-4-methylphenol or styrenated phenol.

Examples of the organic peroxide include dicumyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, α, α'-di-t-butylperoxydi-p-diisopropylbenzene. , N-butyl-
4,4-bis-t-butylperoxyvalerate, t-
Butyl peroxybenzoate, t-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5
Organic peroxides such as -di (t-butylperoxy) hexane can be used alone or in combination.

At this time, sulfur, sulfur compounds such as dipentamethylene thiuram tetrasulfide, oxime compounds such as p-quinone dioxime and p, p'-dibenzoylquinone dioxime, triallyl cyanurate,
Allyl compounds such as diallyl cyanurate, diallyl phthalate, methacrylic compounds such as ethylene dimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, metaphenylene bismaleimide, maleimide compounds such as toluylene bismaleimide, and those The mixture is used as a crosslinking aid.

The compounding amount of the organic peroxide is 100 parts by mass of the rubber component.
It is 0.1 to 10 parts by weight with respect to parts by weight.

[0023]

The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Parts and% in the examples are by weight unless otherwise specified.

The method for measuring the hydrogenated rubber used in the present invention was as follows. That is, the bound styrene content was determined from the calibration curve by infrared method based on the absorption of the phenyl group at 699 cm ^-1 . The vinyl bond content was determined by the infrared method (Morero method). Molecular weight, molecular weight distribution, coupling efficiency (C /
E) is gel permeation chromatography (GP
Calculated from C). The hydrogenation rate was 100 MHz ¹ H measured at 15% concentration using ethylene tetrachloride as a solvent.
-Calculated from the spectral reduction of the unsaturated bond in the NMR spectrum. Next, the method for producing the hydrogenated diene-based copolymer used in the present invention will be described in more detail.

Sample 1 (1) A 5 L autoclave was charged with 2,500 g of degassed and deodorized cyclohexane, 150 g of styrene and 350 g of 1,3-butadiene, and then tetrahydrofuran 2.5
Polymerization was carried out by adding 0.34 g of g and n-butyllithium. The polymerization temperature was 30 to 80 ° C. After the conversion reached almost 100%, 0.14 of silicon tetrachloride was added.
g was added. Then, 2,6-di-tert-butylcatechol was added to decatalyze by the steam stripping method, and dried on a 120 ° C. hot roll to obtain a polymer. The styrene-butadiene copolymer thus obtained had a vinyl bond content of 20%, a styrene content of 15% by weight, and a branched polymer of 40% by weight. The weight average molecular weight by GPC analysis was 320,000, and Mw / Mn was 1.5. (2) The conjugated diene polymer polymerized in (1) was charged into a 3 L autoclave to prepare a 15% cyclohexane solution. After substituting the system with nitrogen, a catalyst solution of nickel naphthenate: n-butyllithium: tetrahydrofuran = 1: 8: 20 (molar ratio) adjusted in advance in another container was used as nickel in an amount of 1 mol per 2000 mol of the olefin moiety. I prepared to become. Then, hydrogen was introduced into the reaction system, and a hydrogen conversion reaction was performed at 70 ° C. After controlling the hydrogenation rate based on the absorbed and consumed amount of hydrogen, the hydrogen in the system was replaced with nitrogen, and 1 PHR of the antioxidant, 6-di-tert-butylparacresol, was added. After repeating contact removal and coagulation, roll drying was performed by a conventional method to obtain a hydrogenated diene-based copolymer having a hydrogenation rate of 85%.

Samples 2 to 7 The vinyl bond content was 40% and the styrene content was 15% in the same manner as in (1) of Sample 1 except that the coupling reaction was not carried out.
A weight percent styrene-butadiene copolymer was obtained. A hydrogenated diene-based copolymer having a hydrogenation rate of 95% was obtained in the same manner as in (2) of Sample 1. In the same manner as described below, Samples 3 to 3 shown in Table 1
A hydrogenated diene-based copolymer of 7 was obtained.

[0027]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 to 4 Compounded rubber (rubber composition) according to the compounding recipe shown in Table 2.
After manufacturing, the roll temperature was adjusted to 60 ± 5 ° C. using a 10-inch test roll machine, and the roll rotation speed was 22 rpm on the front side, 20 rpm on the back side, and the nip width was 2 mm.
Then, 1.2 kg of the compounded rubber was wrapped around a roll, and then the nip width was gradually widened, and the roll gap when the compounded rubber peeled from the roll was used as a measure of the wrapping property. The larger the width, the better the workability.

[0029]

[Table 2]

Further, the mold releasability test method is as follows: a kneaded and unvulcanized sheet having a thickness of 2 mm is 50 × 65 × 2 mm.
External mold release agent is applied only on the upper plate with the mold of 170 ℃ × 1
After press vulcanization for 0 minutes, the release force when removing the vulcanized product from the mold and the sheet tear were evaluated. The number of tests is 10
Repeated times and took the average value. Further, the physical properties and heat resistance were measured according to JIS K6301. The results are shown in Table 3. In the examples, it is clear that the composition of the present invention, which is excellent in mold release and heat resistance and does not impair normal state physical properties, can obtain good effects as a mold composition.

[0031]

[Table 3]

[0032]

Industrial Applicability The present invention relates to a rubber composition for molds, which improves molding defects in molding of molds and is excellent in heat resistance and cold resistance. The rubber composition for molds of the present invention, transportation equipment such as automobiles, ships and aircraft, food, electricity, electronics,
Rubber parts used for general industrial products such as building materials,
For example, various packings, O-rings, oil seals,
It can be widely applied to the fields of bearing seals, brake cups as seal parts for brakes, piston seals, gaskets, belts, boots, diaphragms, especially vibration-proof rubbers required for heat resistance, rolls and the like.
Thus, the molded rubber composition of the present invention has an extremely great industrial value.

Front page continuation (72) Inventor Ken Akiyama 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. A random diene-based copolymer of a conjugated diene and a vinyl aromatic compound, having a molecular weight distribution Mw / M.
n is 10 or less, the vinyl aromatic compound bond content is 5 to 5
0 wt% and the vinyl bond content of the diene part is 10
% Of a diene-based copolymer is hydrogenated, and an organic peroxide is added to the hydrogenated diene-based polymer in which at least 80% of the olefinic unsaturated bond of the polymer is hydrogenated. A rubber composition for molding.