JPH11106441A - Unsaturated nitrile-conjugated diene copolymer rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an unsaturated nitrile-conjugated diene copolymer rubber that can prepare a low-viscosity compound solution suitable for production of blanket without extreme reduction of polymer concentration and a rubber composition containing said copolymer rubber as a rubber component. SOLUTION: The objective unsaturated nitrile-conjugated diene copolymer is a random copolymer comprising 10-45 wt.% of unsaturated nitrile units as acrylonitrile and 90-55 wt.% of conjugated diene units as butadiene and has the number-average molecular weight of 50,000-150,000 according to the GPC in which the proportion of the component with a molecular weight of <=50,000 is 15-25 wt.% in the copolymer, while the proportion of the copolymer with a molecular weight of >=2,000,000 is 5-15 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unsaturated nitrile-conjugated diene-based copolymer rubber, and more particularly, to a solution viscosity lower than that of a conventional copolymer rubber having the same Mooney viscosity. The present invention relates to a novel unsaturated nitrile-conjugated diene copolymer rubber capable of obtaining a low solution viscosity even when a reinforcing agent or the like is blended, and a rubber composition using the same.

[0002]

2. Description of the Related Art A rubber composition (compound) obtained by adding a compounding agent such as a reinforcing filler to acrylonitrile-butadiene copolymer rubber (NBR) is dissolved in a solvent, and the resulting solution composition is used as a base fabric. Blanket coated with a rubber composition layer having a predetermined thickness is used as a blanket cylinder in offset printing.
It is used for N used for such applications
BR is required in terms of workability and productivity that the compound is easily dissolved in a solvent and that the viscosity of the obtained compound solution having a predetermined concentration (compound solution viscosity) is low. However, in order to lower the viscosity of the compound solution, the concentration of the compound must be reduced. As a result, in the production of blankets having a rubber composition layer of a predetermined thickness, the number of coatings increases, and the productivity increases. Is significantly reduced, and improvement is demanded.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an unsaturated nitrile-conjugated diene copolymer which is suitable for producing blankets and the like and which can obtain a low-viscosity compound solution without extremely lowering the concentration. It is to provide a united rubber. Another object of the present invention is to provide a vulcanizable rubber composition having a high vulcanization rate and a high tensile stress using the copolymer rubber as a rubber component, and a solution rubber having a low viscosity and excellent workability. It is to provide a composition as well as a rubber paste. The present inventors have conducted intensive studies and as a result, even if the solution viscosity of the conventional NBR is about the same as the Mooney viscosity,
Paying attention to the fact that the molecular weight distribution has different values, the present invention has been completed based on this finding.

[0004]

Thus, according to the present invention, there is provided a random copolymer comprising 10 to 45% by weight of an unsaturated nitrile unit and 90 to 55% by weight of a conjugated diene unit. Average molecular weight of 50,000-
150,000 and the molecular weight in the copolymer is 50,000
The content of the component having a molecular weight of 2,000,000 or more is 15 to 25% by weight, and the content of the component having a molecular weight of 2,000,000 or more is 5 to 1%.
An unsaturated nitrile-conjugated diene copolymer rubber is provided at 5% by weight. Further, according to the present invention, a vulcanizable rubber composition characterized in that a reinforcing filler and a vulcanizing agent are blended with the above-mentioned copolymer rubber, and the vulcanizable rubber composition as a solvent A solution rubber composition characterized by being dissolved and a rubber paste characterized by comprising the solution rubber composition are provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The unsaturated nitrile-conjugated diene copolymer rubber of the present invention is a rubbery polymer in which unsaturated nitrile and conjugated diene are randomly copolymerized, and has a Mooney viscosity (ML _{1 + 4} , 100 ° C.). ) Is 30 to 150, preferably 50 to 100, the content of unsaturated nitrile units is 10 to 45% by weight, preferably 15 to 40% by weight, and the content of conjugated diene units is 90 to 55% by weight. , Preferably 85 to 60% by weight. When the content of the unsaturated nitrile unit is less than 10% by weight, the oil resistance becomes insufficient and
If it exceeds 5% by weight, the solubility in a solvent is reduced, and a special solvent must be used for preparing a compound solution, which is not preferable.

The unsaturated nitrile-conjugated diene copolymer rubber of the present invention has a number average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) of 50,000 to 150,000, preferably ,
70,000-100,000. Also, the ratio (Mw / Mw) between the weight average molecular weight (Mw) and the number average molecular weight (Mn)
Mn) is preferably in the range of 5 to 8, and more preferably in the range of 5.5 to 7.5. Further, the content of the component having a molecular weight of 50,000 or less in the copolymer is 15 to 25.
%, Preferably 17 to 20% by weight, and the content of the component having a molecular weight of 2,000,000 or more is 5 to 5%.
It is 15% by weight, preferably 6 to 10% by weight.

The solution viscosity of the copolymer rubber (dissolved in toluene when the content of unsaturated nitrile unit is 35% by weight or less, and toluene / methyl ethyl ketone (80/20 B) (measured at 25 ° C. with a B7 viscometer (No. 7 rotor, rotation speed 10 rpm)) at a concentration of 30% by weight by dissolution in a mixed solvent (weight ratio) is usually 10,000 to 500,000 cps, preferably It is 30,000-200,000 cps.

[0008] The gel content of the copolymer rubber (the copolymer rubber cut into a 80 mesh wire net was collected, and the wire net was immersed in methyl ethyl ketone at 25 ° C for 24 hours.
The value obtained by dividing the amount of rubber remaining on the wire net after drying by the amount of collected rubber is expressed as a percentage) is usually 5% by weight or less,
It is preferably at most 1% by weight.

The unsaturated nitrile used for producing the copolymer rubber of the present invention includes, for example, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, etc., with acrylonitrile being preferred. Examples of the conjugated diene used in the present invention include 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, and 1,3-pentadiene.

[0010] The unsaturated nitrile-conjugated diene copolymer rubber of the present invention can be obtained by copolymerizing an unsaturated nitrile and a conjugated diene. Copolymer rubbers obtained by copolymerizing other monomers with the content of these monomer units in the copolymer being 10% by weight or less are also included.

Other copolymerizable monomers include, for example, aromatic vinyl compounds such as styrene, α-methylstyrene and vinyltoluene; acrylic acid, methacrylic acid,
Α, β-unsaturated carboxylic acids such as maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, fumaric anhydride and anhydrides thereof; methyl (meth) acrylate;
Alkyl esters of α, β-unsaturated carboxylic acids such as ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; mono (di) ethyl maleate, mono (di) butyl maleate;
Mono (di) ethyl fumarate, mono (di) fumarate-2-
Α, β such as ethylhexyl and n-butyl itaconate
Mono- (di) esters of unsaturated dicarboxylic acids; alkoxyalkyl esters of α, β-unsaturated carboxylic acids such as methoxyethyl (meth) acrylate, methoxypropyl acrylate, butoxyethyl (meth) acrylate; 2-hydroxyethyl acrylate; And hydroxyalkyl esters of α, β-unsaturated carboxylic acids such as hydroxypropyl acrylate.

Although the method for producing the copolymer rubber of the present invention is not particularly limited, it can be usually obtained by polymerizing the above-mentioned monomer by an emulsion polymerization technique. emulsifier,
As the molecular weight regulator and other polymerization agents, any of those used in ordinary emulsion polymerization of NBR can be used, and are not particularly limited. Examples of the molecular weight regulator include n-dodecyl mercaptan, t-dodecyl mercaptan, 2,2 ', 4,6,6'-pentamethylheptane-4-mercaptan and 2,4,4-trimethylpentane-2-mercaptan Alkylmercaptan compounds such as 2,2,6,6-tetramethylheptane-4-methanemercaptan; xanthogen disulfides such as dimethyl xanthogen disulfide and diisopropylxanthogen disulfide; tetramethylthiuram disulfide and tetraethylthiuram disulfide Thiuram disulfides; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; and terpene compounds such as terpinolene, α-terpinene, γ-terpinene and dipentene. The amount of these used is usually in the range of 0.1 to 15.0 parts by weight based on 100 parts by weight of the monomer.

Examples of the emulsifier include anionic emulsifiers such as potassium oleate, sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether, polyoxyethylene / propylene block polymer, and polyoxyethylene fatty acid. Examples include nonionic emulsifiers such as esters. These amounts are usually 100
It is in the range of 0.1 to 20 parts by weight based on parts by weight.

The copolymer rubber of the present invention comprises the above-mentioned monomer,
It is manufactured by emulsion polymerization using a molecular weight regulator, an emulsifier and other agents for emulsion polymerization. In contrast to conventional NBR polymerized at a low temperature of about 5 to 15 ° C., the present invention uses a relatively high temperature. Need to be polymerized. Specifically, usually 15 ~ 60 ℃, preferably 20 ~ 50 ℃,
More preferably, it is necessary to carry out the polymerization at a temperature of 30 to 40 ° C. If the polymerization temperature is lower than 15 ° C., the viscosity of the compound solution of the obtained copolymer rubber becomes high, and if it exceeds 60 ° C., a gel insoluble in a solvent is formed, which is suitable for use in which the obtained copolymer is used in a solution state. Absent.

Since the polymerization is carried out at a relatively high temperature as described above, preferred examples of the polymerization initiator include sodium persulfate, potassium persulfate and ammonium persulfate. Redox initiators and the like which are used in combination can also be used.

After completion of the emulsion polymerization, an antioxidant is added to the produced polymer latex, and the produced polymer is coagulated by a coagulant according to a conventional method, washed with water and dried to recover the copolymer of the present invention. You.

The unsaturated nitrile-conjugated diene copolymer rubber of the present invention is characterized by the same Mooney viscosity (ML).
_{(1 + 4} , 100 ° C.), the solution viscosity of the same concentration and the solution viscosity of the compound solution are lower than those of the conventional NBR having the same viscosity. It is not clear why the solution viscosity of the copolymer rubber of the present invention and the solution viscosity of the compound show lower values as compared with the conventional NBR. However, as a characteristic of the molecular weight distribution of the copolymer rubber of the present invention, the molecular weight is 50%. One of the reasons is that the content ratio of the relatively low molecular weight component of 2,000 or less is larger than that of the conventional NBR.

The copolymer rubber of the present invention can be used as a vulcanizable rubber composition by blending ordinary reinforcing fillers, vulcanizing agents and other compounding agents used in the rubber field.

Examples of the reinforcing filler include various carbon blacks; silica, silicate, anhydrous silicate, hydrous silica and synthetic silicate in the form of ultrafine bulky white powder having a particle size of 10 to 15 μm. Silica such as activated calcium carbonate, heavy calcium carbonate, and special calcium carbonate; basic magnesium carbonate; ultrafine powdered magnesium silicate; hard clay; talc; diatomaceous earth; The amount of the reinforcing filler is not particularly limited, but is usually 5 to 100 parts by weight, preferably 2 to 100 parts by weight, based on 100 parts by weight of the copolymer rubber.
0 to 80 parts by weight. If the amount of the reinforcing filler is too small, the wear resistance and strength of the rubber vulcanizate are low, and conversely,
If the amount of the reinforcing filler is excessive, the moldability and the elongation at break of the rubber vulcanizate are reduced.

As the vulcanizing agent to be added to the vulcanizable rubber composition, a vulcanizing agent which is usually used as an NBR vulcanizing agent can be used. Examples of such a vulcanizing agent include a sulfur-based vulcanizing agent and an organic peroxide vulcanizing agent. Although the amount of the vulcanizing agent is not particularly limited, it is usually 0.10 to 10 based on 100 parts by weight of the copolymer rubber.
Parts by weight, preferably 0.1 to 5 parts by weight.

Examples of the sulfur-based vulcanizing agent include sulfur such as powdered sulfur, sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur and insoluble sulfur; sulfur chloride, sulfur dichloride, morpholine.
Disulfide, alkylphenol disulfide, N, N'-dithio-bis (hexahydro-2H-
Azenopin-2), sulfur-containing compounds such as phosphorus-containing polysulfides, high molecular polysulfides, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, 2-
Sulfur donating compounds such as vulcanization accelerators such as (4'-morpholinodithio) benzothiazole.

Further, together with these sulfur vulcanizing agents,
Vulcanization aids such as zinc white and stearic acid; guanidine,
Vulcanization accelerators such as aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea and xanthate can be used. These amounts are not particularly limited, and usually, the copolymer rubber 1
The vulcanization aid and the vulcanization accelerator are each used in an amount of 0.1 to 5 parts by weight with respect to 00 parts by weight.

Examples of the organic peroxide vulcanizing agent include dicumyl peroxide, cumene hydroperoxide,
t-butylcumyl peroxide, di-t-butyl peroxide, 1,3- and 1,4-bis (t-butylperoxyisopropyl) benzene, 1,1-di-t-butylperoxy-3,3 -Trimethylcyclohexane,
4,4-bis- (t-butyl-peroxy) -n-butylvalerate, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-
Di-t-butylperoxyhexyne-3,1,1-di-
t-butylperoxy-3,5,5-trimethylcyclohexane, p-chlorobenzoyl peroxide, t-
Butyl peroxyisopropyl carbonate, t-butyl benzoate and the like.

As the vulcanization aid together with the above-mentioned organic peroxide vulcanizing agent, polyfunctional monomers such as trimethylolpropane trimethacrylate, divinylbenzene, ethylene dimethacrylate and triallyl isocyanurate are used. The amount of these vulcanization aids is not particularly limited, but is usually in the range of 0.5 to 20 parts by weight based on 100 parts by weight of the copolymer rubber.

Further, when another rubber is used in combination with the copolymer rubber of the present invention, a vulcanizing agent other than the above may be used.
For example, metal soap / sulfur vulcanizing agent, triazine / dithiocarbamate compound, polycarboxylic acid / onium salt compound, polyamine compound (hexamethylenediamine, triethylenediamine, triethylenetetramine, hexamethylenediaminecarbamate, ethylenediaminecarbamate Etc.) can be used in combination as necessary.

The vulcanizable rubber composition may contain a silane coupling agent together with the reinforcing filler. As the silane coupling agent, those conventionally used in the rubber field can be used. Among them, a silane coupling agent having a vinyl group is preferable because it contributes to improvement in heat resistance. The use amount of the silane coupling agent is preferably in the range of 0.5 to 10 parts by weight based on 100 parts by weight of the copolymer rubber. Examples of the silane coupling agent having a vinyl group include vinyltrichlorosilane, vinyltriacetoxysilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, N′-
And vinylbenzyl-N-trimethoxysilylpropylethylenediamine salt.

Further, if necessary, the vulcanizable rubber composition may contain other compounding agents usually used in the rubber field, for example, process oils, plasticizers, antioxidants, antiozonants, non-reinforcing agents. The filler may be blended. Further, the vulcanizable rubber composition, if necessary, the copolymer rubber of the present invention and acrylic rubber, fluoro rubber, styrene-butadiene copolymer rubber, ethylene-propylene-diene terpolymer rubber, Natural rubber, polyisoprene rubber and the like can be used in combination.

The method for producing the above-mentioned vulcanizable rubber composition is not particularly limited, but the rubber composition is prepared by using a conventional mixer such as a roll or a Banbury mixer with a copolymer rubber, a reinforcing filler, a vulcanizing agent, It can be produced by kneading and mixing with other compounding agents.

Since the copolymer rubber of the present invention has a lower solution viscosity than that of conventional NBR, a solution prepared by dissolving the vulcanizable rubber composition in an appropriate soluble solvent is used. The solution viscosity of the rubber composition also shows a low value. Examples of the soluble solvent include, but are not particularly limited to, aromatic solvents such as benzene and toluene, and ketone solvents such as acetone and methyl ethyl ketone. The concentration of the rubber composition in the solution rubber composition is not particularly limited, but is usually 10 to 50% by weight.

[0030] Such a solution rubber composition is prepared by using a conventional N
Since the solution viscosity of the solution rubber composition using BR is lower than the solution viscosity of the solution rubber composition, for example, a solution rubber composition is applied to a predetermined base cloth like a roll blanket, and a rubber having a predetermined thickness is used. In the use of a rubber paste for forming a composition layer, it can be expected to improve workability and productivity. Examples of the use of the rubber paste include a roll blanket, a rubberized cloth, a tire cord, a rubber hose,
Examples include backsizing agents for wire coating, synthetic leather, raincoats, carpets and the like.

[0031]

The present invention will be specifically described below with reference to examples and comparative examples. In the following, parts and percentages are by weight unless otherwise specified.

Examples 1 to 6 and Comparative Examples 1 to 3 [1] Production of copolymer rubber (NBR) In a reaction vessel having an internal volume of 10 liters, 150 parts of water and an amount of bound acrylonitrile were 33% or 40%. Charge a total of 100 parts of acrylonitrile and butazine in a certain ratio,
Potassium oleate was used as an emulsifier, t-dodecylmercaptan was used as a molecular weight regulator, and 0.3 part of potassium persulfate was further charged as a polymerization initiator. After sufficiently degassing, emulsion polymerization was performed at a polymerization temperature shown in Tables 1 and 2. Started. When the polymer conversion reached 80%, the polymerization was stopped by adding 0.2 parts of hydroxylamine sulfate to the reaction vessel. Next, the contents of the reaction vessel were heated to 70 ° C., unreacted monomers were recovered by steam distillation under reduced pressure, 2 parts of an antioxidant (alkylated phenol) was added, and the resulting latex was stirred. The copolymer rubber was coagulated by pouring into the coagulant (calcium chloride) solution below. Separation and collection of crumbs,
After washing with water, it was dried under reduced pressure at 50 ° C. to obtain NBR.

The obtained acrylonitrile content, Mooney viscosity, solution viscosity, molecular weight distribution and molecular weight of each NBR, and the rubber composition obtained by kneading each NBR and each compounding agent in accordance with the following compounding recipe, were prepared. Sulfur properties were measured by the following methods. The above measurement results are shown in Tables 1 and 2. [2] Measurement method (1) Properties of NBR (1) Amount of bound acrylonitrile (%) Determined by calculation from the nitrogen content in NBR measured by the Kjeldahl method according to JIS K6384. (2) Mooney viscosity (ML _{1 + 4} , 100 ° C.) Measured according to JIS K6383. (3) Solution viscosity (cps) A solution having a concentration of 30% is prepared and measured at 25 ° C. using a Brookfield viscometer (Brookfield viscometer: No. 7 rotor, rotation speed: 10 rpm). In the case of NBR having a bound acrylonitrile content of 33%, toluene is used, and in the case of NBR having a bound acrylonitrile content of 40%, toluene / methyl ethyl ketone (80/20 weight ratio) is used.

(4) Amount of gel (%) NBR in the form of small pieces was placed in a basket made of a 80-mesh stainless steel wire mesh, and placed in methyl ethyl ketone at 25 ° C for 24 hours.
After soaking for a period of time, the cage is taken out, the solvent is sufficiently evaporated, and the weight of the NBR remaining without being dissolved in the cage is measured. The ratio of the weight of the residual NBR to the weight of the NBR before immersion in the solvent is determined, and this ratio is defined as the gel amount. (5) Molecular weight distribution and molecular weight The number average molecular weight (Mn) and the weight average molecular weight (Mw) in terms of standard polystyrene are determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent. The entire area of the molecular weight distribution curve and the area of the part where the molecular weight is 50,000 or less and 2,000,000 or more are determined, and the ratio of the area of these parts to the total area is determined by the content ratio of these molecular weight components (% by weight). ).

(2) Physical Properties of Rubber Composition Preparation of Rubber Composition A rubber composition for blanket was prepared using a Banbury mixer according to the following formulation. (1) Mooney viscosity of compound (rubber composition) Same as (2) of (1). (2) Solution viscosity of compound (cps) Same as (3) in (1). (3) Vulcanization (ODR test) Vulcanization time (T ₅ , T ₉₅ ) (unit: minute) and maximum torque MH at 160 ° C. using an oscillating disc rheometer according to the Japan Rubber Association Standard SRIS 3102. (Unit: kgf · cm) is measured.
(T ₉₅ -T ₅₎ as vulcanization rate value is small fast indicates a higher crosslinking efficiency as the value of MH is high.

(3) Properties of vulcanized material The rubber composition was press-vulcanized at 160 ° C. for 20 minutes to prepare a test piece, and the tensile strength (T) was measured in accordance with JIS K6301.
B), tensile stress (M) (for example, M100 means 100% tensile stress) (the unit is kgf / cm ² ) and elongation at break (EB (%)) are measured. The hardness (HS) is measured using a JIS spring type A hardness tester.

Formulation Copolymer 100 parts Calcium carbonate (* 1) 15 parts Silica (* 2) 5 parts White sub (* 3) 5 parts Zinc oxide 5 parts Stearic acid 1 part Sulfur 2 parts Dibenzothiazyl disulfide 1 .5 parts Tetramethylthiuram disulfide 1.5 parts (Note) (* 1) Silver W manufactured by Shiraishi Kogyo Co., Ltd. (* 2) Tok Seal GU manufactured by Tokuyama Co., Ltd. (* 3) Manufactured by Temma Sub Kako

[0038]

[Table 1]

[0039]

[Table 2]

From the results shown in Table 1, the NBR (C) of the present invention was obtained.
(Example 3) has a lower solution viscosity while having the same Mooney viscosity value as compared with the conventional NBR (D) (Comparative Example 1), and a component having a molecular weight of 50,000 or less and 2,000. It can be seen that the proportion of components of 2,000 or more is large. Furthermore, the solution viscosity of the compound (rubber composition) using the NBR of the present invention also shows a lower value than that using the conventional NBR, the vulcanization rate of the rubber composition is high, and the vulcanization properties are good. It can be seen that From the results in Table 2, it can be seen that even for the NBR having the bound acrylonitrile content of 40%, the NBR (F and G) of the present invention has the NBR content of the bound acrylonitrile content of 33% as compared with the conventional NBR (H and I).
As in the case of BR, it can be seen that the solution viscosity and the solution viscosity of the compound were low and the vulcanization properties were also good.

[0041]

According to the present invention, the solution viscosity is lower than that of NBR having the same Mooney viscosity, and a lower solution viscosity can be obtained even when various reinforcing fillers are blended. Provided is an unsaturated nitrile-conjugated diene copolymer rubber. The copolymer rubber of the present invention having such characteristics is a rubber suitable for producing blanket rolls, coated cloths and the like which are used in the form of a solution by dissolving a rubber composition in a solvent.

Preferred embodiments of the invention described in claims 1 to 4 of the present invention are as follows. (1) The Mooney viscosity of the unsaturated nitrile-conjugated diene copolymer rubber is 30 to 150, preferably 50 to 100.
It is. (2) The content of unsaturated nitrile units in the copolymer rubber is 15 to 40% by weight. (3) The content of the conjugated diene unit in the copolymer rubber is:
85 to 60% by weight. (4) The number average molecular weight of the copolymer rubber is 70,000
~ 100,000. (5) Mw / Mn of the copolymer rubber is preferably 5 to
8, more preferably 5.5 to 7.5. (6) The content of the copolymer rubber having a molecular weight of 50,000 or less is 17 to 20% by weight. (7) The content of the component having a molecular weight of 2,000,000 or more of the copolymer rubber is 6 to 10% by weight. (8) The solution viscosity of the copolymer rubber is 10,000 to 5
00,000, preferably 30,000-200,00
0 cps. (9) The unsaturated nitrile is acrylonitrile. (10) The conjugated diene is butadiene. (11) The polymerization temperature of the emulsion polymerization of the copolymer rubber is 15
-60 ° C, preferably 20-50 ° C, more preferably 30-40 ° C. (12) The amount of the reinforcing filler in the vulcanizable rubber composition is from 5 to 100 per 100 parts by weight of the copolymer rubber.
Parts by weight, preferably 20 to 80 parts by weight. (13) The compounding amount of the vulcanizing agent in the vulcanizable rubber composition is as follows:
It is 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the copolymer rubber. (14) The concentration of the solution rubber composition is 10 to 50% by weight.
It is. (15) The rubber paste is used for roll blankets.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C09J 109/02 C09J 109/02 // (C08F 236/12 220: 42)

Claims (4)

[Claims] 1. A random copolymer comprising 10 to 45% by weight of unsaturated nitrile units and 90 to 55% by weight of conjugated diene units, having a number average molecular weight of 5 as measured by GPC.
The content of components having a molecular weight of 50,000 to 150,000 and a molecular weight of 50,000 or less in the copolymer is 15 to 25.
An unsaturated nitrile-conjugated diene copolymer rubber characterized in that the content of a component having a molecular weight of 2,000,000 or more is 5 to 15% by weight. 2. A vulcanizable rubber composition comprising the unsaturated nitrile-conjugated diene copolymer rubber according to claim 1 and a reinforcing filler and a vulcanizing agent. 3. A solution rubber composition obtained by dissolving the vulcanizable rubber composition according to claim 2 in a solvent. 4. A rubber paste comprising the solution rubber composition according to claim 3.