JP2002060437A - Conjugated diene rubber gel, rubber composition containing the same and process for producing conjugated diene rubber gel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition which has excellent wear resistance and a low heat build-up capability while retaining good mechanical characteristics and is suitable for a tire material. SOLUTION: The rubber composition contains a conjugated diene rubber gel which consists of 80-99 wt.% conjugated diene units and 20-1 wt.% aromatic vinyl units and which has an index of swelling with toluene of 16 to 70, and a rubber crosslinkable with sulfur. The conjugated diene rubber gel is advantageously produced by the emulsion copolymerization of 50-99.9 wt.% conjugated diene, 0-30 wt.% aromatic vinyl, 0-20 wt.% of other ethylenically unsaturated monomer, and 0.1-20 wt.% crosslinking monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel conjugated diene rubber gel, a rubber composition containing the same, and a method for producing a conjugated diene rubber gel, and more particularly to a tire excellent in abrasion resistance and low heat generation. The present invention relates to a conjugated diene-based rubber gel capable of providing a novel rubber composition, a rubber composition containing the conjugated diene-based rubber gel, and a method for producing a conjugated diene-based rubber gel capable of producing a conjugated diene-based rubber gel with high productivity.

[0002]

2. Description of the Related Art In recent years, rubber compositions for tires of automobiles and the like have been required to be improved in various performances. In particular, rubber compositions for sidewalls and beads are required to have improved mechanical properties and abrasion resistance. There is a demand for a material having excellent heat resistance and low rolling resistance (low heat generation) when a tire is formed.

[0003] Natural rubber is used in large quantities as rubber for tires, but in order to improve various performances, other rubbers are often mixed and used. For example, a polybutadiene rubber is mixed to improve abrasion resistance, and a styrene-butadiene copolymer rubber is mixed and used to improve mechanical properties. However, when the wear resistance is improved, the mechanical properties are reduced, and when the mechanical properties are improved, the low heat generation is reduced, and various performances are often in a trade-off relationship, and all the performances are improved. It is difficult.

On the other hand, a rubber raw material is generally required to have a gel structure as little as possible in consideration of the kneading properties of the rubber raw material and a reinforcing material. However, in order to improve low heat generation and abrasion resistance. It has been proposed to use a rubber gel having a gel structure. For example, JP-A-3-37246 discloses a rubber composition containing polychloroprene gel. Although this rubber composition is excellent in low heat build-up and abrasion resistance, since the polychloroprene gel contains chlorine, in consideration of treating scrap tires by incineration, it is not actually used as a rubber raw material for tires. Have difficulty.

As for conjugated diene rubbers, JP-A-6-57038 discloses a rubber composition containing a polybutadiene gel, and JP-A-10-204217 discloses a rubber composition containing a styrene-butadiene copolymer rubber gel. A rubber composition is disclosed. These rubber compositions are
Although excellent in low heat build-up, the abrasion resistance may be insufficient or the elongation at break may be reduced to lower the mechanical properties.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, a first object of the present invention is to provide a novel conjugate which can provide a rubber composition having excellent wear resistance and low heat build-up without impairing mechanical properties. An object of the present invention is to provide a diene rubber gel. A second object of the present invention is to provide a rubber composition having excellent abrasion resistance and low heat generation without impairing mechanical properties.
A third object of the present invention is to provide a method for producing a conjugated diene rubber gel capable of producing a conjugated diene rubber gel with high productivity.

[0007]

Thus, according to the present invention, firstly, 80 to 99% by weight of a conjugated diene monomer unit and 20 to 1% by weight of an aromatic vinyl monomer unit,
A conjugated diene rubber gel having a toluene swelling index of 16 to 70 is provided. Second, the conjugated diene monomer unit 80
A conjugated diene rubber gel having a swelling index of 16 to 70 and a rubber capable of being crosslinked with sulfur, which is composed of -99% by weight and 20-1% by weight of an aromatic vinyl monomer unit. A rubber composition is provided. Third
50 to 99.9% by weight of a conjugated diene monomer, 0 to 30% by weight of an aromatic vinyl monomer, 0 to 20% by weight of other ethylenically unsaturated monomer units, and 0 of a crosslinkable monomer. .1
A method for producing a conjugated diene-based rubber gel having a toluene swelling index of 70 or less, characterized by emulsion-copolymerizing a monomer mixture of from 20 to 20% by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The conjugated diene rubber gel, the rubber composition and the method for producing the conjugated diene rubber gel of the present invention are described in detail below. Conjugated diene rubber gel The conjugated diene rubber gel of the present invention comprises 80 to 99% by weight of conjugated diene monomer unit, preferably 83 to 95% by weight, more preferably 86 to 90% by weight, and aromatic vinyl monomer unit. 20-1% by weight, preferably 17-5% by weight,
More preferably, it comprises 14 to 10% by weight. The conjugated diene rubber gel can be produced with or without a crosslinkable monomer, but is preferably obtained by copolymerization with a crosslinkable monomer. Furthermore, if desired, a copolymerizable ethylenically unsaturated monomer may be used.

Accordingly, the conjugated diene-based rubber gel of the present invention usually comprises 80 to 99% by weight of a conjugated diene monomer unit, 1 to 20% of an aromatic vinyl monomer unit, and other ethylenically unsaturated monomer units. 0 to 19% by weight, and 0 to 1.5% by weight of a crosslinking monomer unit. Preferred conjugated diene rubber gel is 83 to 95% by weight of a conjugated diene monomer unit,
5 to 17% of aromatic vinyl monomer units, 0 to 5% by weight of other ethylenically unsaturated monomer units, and 0 to 1% by weight of crosslinkable monomer units; more preferred conjugated diene rubber gel is 86 to 90% by weight of a conjugated diene monomer unit,
It comprises 10 to 14% of aromatic vinyl monomer units, 0 to 1% by weight of other ethylenically unsaturated monomer units, and 0 to 0.5% by weight of crosslinkable monomer units. If the amount of the conjugated diene monomer unit in the conjugated diene rubber gel is small, the mechanical properties of the cross-linked rubber are poor, and if it is large, the abrasion resistance of the cross-linked rubber is poor. If the amount of the aromatic vinyl monomer unit is small, the abrasion resistance of the rubber crosslinked product is poor, and if it is too large, the low heat buildup of the rubber crosslinked product is poor.
If the amount of other optional ethylenically unsaturated monomer units is large, it is difficult to obtain a rubber crosslinked product having both mechanical properties, abrasion resistance and low heat generation. The use of a crosslinkable monomer is optional, but has the following range of toluene swelling index and is advantageous for industrially producing a rubber crosslinked product having desired mechanical properties, abrasion resistance and low heat generation. It is preferable that 0.1 to 1.5% by weight of a crosslinkable monomer unit is present.

Further, the conjugated diene rubber gel of the present invention is characterized by having a toluene swelling index of 16 to 70. The toluene swelling index is preferably 17-5.
0, more preferably 19 to 45, particularly preferably 20 to 45
40. If the toluene swelling index is small, the rubber composition containing the reinforcing material will have an increased Mooney viscosity, resulting in reduced workability, reduced elongation in the cross-linked rubber, and reduced wear resistance. Also, when this index is large, the rubber crosslinked product is inferior in wear resistance and low heat build-up.

The toluene swelling index of the conjugated diene rubber gel is calculated from the weight of the gel containing toluene and the weight of the gel when dried, as (weight when the gel contains toluene) / (weight when dried). Specifically, the measurement is performed as follows. 250 mg of conjugated diene rubber gel
Shake in 5 ml for 24 hours to swell. The swollen gel is centrifuged by a centrifugal separator under the condition that a centrifugal force of 400,000 m / sec ² or more is applied, the swollen gel is weighed in a wet state, and then dried at 70 ° C. until a constant weight is obtained.
Re-weigh the gel after drying. (Wet gel weight)
The toluene swelling index is measured as // (weight of gel after drying).

The conjugated diene monomer is not particularly limited, but specific examples thereof include 1,3-butadiene and 2-
Methyl-1,3-butadiene, 1,3-pentadiene, 2
-Chloro-1,3-butadiene and the like. Among them, 1,3-butadiene and 2-methyl-1,3-butadiene are preferred, and 1,3-butadiene is most preferred. The conjugated diene monomer may be used alone or
More than one kind may be mixed and used.

The aromatic vinyl monomer is an aromatic monovinyl compound, and specific examples thereof include, but are not particularly limited to, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and 2,4-dimethylstyrene. styrene,
o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, pt-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene , P-
Bromostyrene, 2-methyl-4,6-dichlorostyrene, 2,4-dibromostyrene, vinylnaphthalene and the like can be mentioned. Of these, styrene is preferred.

If desired, the ethylenically unsaturated monomer copolymerized with the conjugated diene monomer and the aromatic vinyl monomer is not particularly limited, but may be an α, β-ethylenically unsaturated carboxylic acid ester monomer , Α, β-ethylenically unsaturated nitrile monomer, α, β-ethylenically unsaturated carboxylic acid monomer, α, β-ethylenically unsaturated carboxylic acid amide monomer, olefin monomer, etc. Is mentioned.

The α, β-ethylenically unsaturated carboxylic acid ester monomers include alkyl esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and lauryl methacrylate; methoxyethyl acrylate, methoxy Alkoxy-substituted alkyl esters such as ethoxyethyl acrylate; cyano-substituted alkyl esters such as cyanomethyl acrylate, 2-cyanoethyl acrylate and 2-ethyl-6-cyanohexyl acrylate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and the like Hydroxy-substituted alkyl esters; epoxy-substituted alkyl esters such as glycidyl acrylate and glycidyl methacrylate; N, N ' Amino substituted alkyl esters such as dimethylaminoethyl acrylate; 1,1,
Halogen-substituted alkyl esters such as 1-trifluoroethyl acrylate; maleic acid diethyl ester,
Complete alkyl esters of polycarboxylic acids such as dibutyl fumarate and dibutyl itaconate; and the like.

Specific examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile. α, β-ethylenically unsaturated carboxylic acid monomers include monocarboxylic acids such as acrylic acid and methacrylic acid; polycarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; monobutyl ester fumarate and maleic acid Partial alkyl esters of polyvalent carboxylic acids such as monobutyl ester and itaconic acid monoethyl ester;

The α, β-ethylenically unsaturated carboxylic acid amide monomers include acrylamide, methacrylamide, N, N′-dimethylacrylamide, N-butoxymethylacrylamide, N-butoxymethylmethacrylamide, N-methylolacrylamide , N, N'-
Dimethylolacrylamide and the like. As the olefin monomer, preferably, a chain or cyclic monoolefin compound having 2 to 10 carbon atoms, for example, ethylene, propylene, 1-butene, cyclopentene, 2-norbornene and the like are exemplified. In addition to the above, monomers such as vinyl chloride, vinylidene chloride, and vinylpyridine are exemplified. The above ethylenically unsaturated monomers may be used alone or as a mixture of two or more.

The number of crosslinkable monomers used for efficiently forming a gel structure is at least two, preferably two to two.
4 carbon-carbon 2 copolymerizable with a conjugated diene monomer
It is a compound having a heavy bond. Specific examples thereof include polyvalent vinyl aromatic compounds such as diisopropenylbenzene, divinylbenzene, triisopropenylbenzene, and trivinylbenzene; α, β-ethylenically unsaturated compounds such as vinyl acrylate, vinyl methacrylate, and allyl methacrylate. Unsaturated ester compounds of saturated carboxylic acids; unsaturated ester compounds of polycarboxylic acids such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate; ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diester Unsaturated ester compounds of polyhydric alcohols such as methacrylate; 1,2-polybutadiene, divinyl ether, divinyl sulfone, N, N'-m-phenylenemaleimide;

Aliphatic or aromatic diols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and bisphenol A; polyethylene glycol having 2 to 20, preferably 2 to 8, oxyethylene units Unsaturated polyester compounds produced from polyols such as glycerin, trimethylolpropane, pentaerythritol and sorbitol; and unsaturated polycarboxylic acids such as maleic acid, fumaric acid and itaconic acid. . Among them, divinylbenzene is preferred. Divinylbenzene has an ortho form, a meta form and a para form, and may be used alone or in a mixture thereof.

The particle diameter of the conjugated diene rubber gel of the present invention is preferably 5 to 1,000 nm, more preferably 2 to 1,000 nm.
It is 0 to 400 nm, particularly preferably 50 to 200 nm. By the way, this particle size, conjugated diene rubber gel,
After dyeing and fixing with osmium tetroxide or the like, it is a weight average particle diameter obtained by observing with a transmission electron microscope or the like and measuring the diameter of about 100 rubber gel particles.

The method for producing the conjugated diene-based rubber gel of the present invention is not particularly limited, and (1) is directly produced by emulsion polymerization using a crosslinkable monomer, and (2) the emulsion polymerization reaction is highly converted. (3) A diene rubber latex particle having no gel structure, produced by emulsion polymerization, having a cross-linking action, by forming a gel structure in the latex particles by continuing to a conversion rate of, for example, about 90% by weight or more. (4) An organic solvent solution of the rubber polymer obtained by the solution polymerization is emulsified in water in the presence of an emulsifier, and the obtained emulsion is removed before or after removing the organic solvent. Later, it can be produced by a method such as post-crosslinking with a compound having a crosslinking action. Each of the above methods (1), (2) and (3) can be used alone,
You may employ in combination.

However, in order to efficiently produce the conjugated diene rubber gel of the present invention, a method of directly producing it by emulsion polymerization using a crosslinkable monomer is preferred. In the case of direct production by emulsion polymerization, the amount of the crosslinkable monomer used, the amount of the chain transfer agent used, and the conversion at the termination of the polymerization may be adjusted so that the toluene swelling index becomes a desired index. .

When the conjugated diene rubber gel of the present invention is produced by emulsion polymerization using a crosslinkable monomer, the amount of the crosslinkable monomer used is usually 0.1% based on 100% by weight of all monomers.
It is from 1 to 1.5% by weight, preferably from 0.1 to 1% by weight, more preferably from 0.2 to 0.5% by weight. When a conjugated diene-based rubber gel is produced by using a crosslinkable monomer in combination, the resulting conjugated diene-based rubber gel has a conjugated diene monomer unit of 80%.
９８98.9% by weight, preferably 83-94.9% by weight, more preferably 86-89.8% by weight, aromatic vinyl monomer unit 19.9-1% by weight, preferably 16.9-5% Wt%, more preferably 13.8 to 10 wt%, other ethylenically unsaturated monomer units 0 to 19 wt%, preferably 0 to 5 wt%, more preferably 0 to 1 wt%, and
0.1 to 1.5% by weight, preferably 0.1% by weight of crosslinkable monomer units.
It comprises from 1 to 1% by weight, more preferably from 0.2 to 0.5% by weight.

Examples of the compound having a cross-linking effect used in post-crosslinking the diene rubber latex particles include dicumyl peroxide, t-butyl cumyl peroxide, and bis-cumene.
(T-butyl-peroxy-isopropyl) benzene,
Di-t-butyl peroxide, benzoyl peroxide, 2,2
Organic peroxides such as 4-dichlorobenzoyl and t-butyl perbenzoate; Organic azo compounds such as azobisisobutyronitrile and azobiscyclohexanenitrile; Dimercaptoethane, 1,6-dimercaptohexane, Dimercapto compounds such as 3,5-trimercaptotriazine or polymercapto compounds; and the like. Among them, organic peroxides are preferred.

The reaction conditions at the time of post-crosslinking depend on the reactivity and the amount of these compounds having a crosslinking action, but are from a normal pressure to a high pressure (about 1 MPa), from room temperature to
A reaction temperature of about 170 ° C. and a reaction time of about 1 minute to 24 hours are appropriately selected. The kind of the compound having a cross-linking action, the amount of the compound added, the reaction conditions and the like are adjusted so as to obtain a desired toluene swelling index.

The method for producing a conjugated diene-based rubber gel of the production method invention of the conjugated diene rubber gel is a conjugated diene monomer from 50 to 99.9 wt%, the aromatic vinyl monomer 0
To 30% by weight, other ethylenically unsaturated monomer units 0
To 20% by weight, and 0.1 to 20% by weight of a crosslinkable monomer
Is characterized in that a conjugated diene rubber gel having a toluene swelling index of 70 or less is obtained by emulsion copolymerization of a monomer mixture consisting of

The monomer composition used in the emulsion copolymerization is 50 to 99.9% by weight, preferably 70 to 99.9% by weight, of the conjugated diene monomer.
-94.9% by weight, more preferably 74-89.9% by weight, particularly preferably 79.5-85.8% by weight, aromatic vinyl monomer 0-30% by weight, preferably 5-28% by weight. , More preferably 10 to 25 weight, particularly preferably 1 to
4-20% by weight, other ethylenically unsaturated monomers 0
20% by weight, preferably 0-5% by weight, more preferably 0-1% by weight, and 0.1-20% by weight of the crosslinkable monomer, preferably 0.1-2% by weight, more preferably 0.1% by weight. 1
To 1% by weight, particularly preferably 0.2 to 0.5% by weight.

If the amount of the conjugated diene monomer is small, the mechanical properties of the cross-linked rubber are inferior. If the amount is large, the abrasion resistance of the cross-linked rubber is inferior. If the amount of the aromatic vinyl monomer is small, the abrasion resistance of the cross-linked rubber is poor, and if it is large, the low heat build-up of the cross-linked rubber is poor.
If the amount of the other ethylenically unsaturated monomer as an optional component is large, it becomes difficult to obtain a rubber crosslinked product having both mechanical properties, abrasion resistance and low heat generation. If the amount of the cross-linkable monomer is small, the abrasion resistance and low heat build-up of the rubber cross-linked product are inferior. If the amount is large, the Mooney viscosity of the rubber composition containing the reinforcing material increases, and the processability decreases. The wear resistance of the object decreases.

Conjugated diene monomer, aromatic vinyl monomer,
Other ethylenically unsaturated monomers and crosslinkable monomers are respectively the same as those described above. When performing emulsion copolymerization, the method and conditions are not particularly limited,
Emulsifiers, polymerization initiators, chain transfer agents, polymerization terminators, antioxidants and the like conventionally used in emulsion polymerization can be used.

The emulsifier is not particularly limited, but fatty acid soap and rosin acid soap are used. As a specific example, fatty acid soap is a long-chain aliphatic carboxylic acid having 12 to 18 carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and the like, and sodium of these mixed aliphatic carboxylic acids. Selected from salts or potassium salts. Also, the rosin acid soap is selected from sodium or potassium salts of disproportionated or hydrogenated natural rosins such as gum rosin, wood rosin or tall oil rosin. The amount of the emulsifier is not particularly limited, but is usually, per 100 parts by weight of the monomer,
0.05 to 15 parts by weight, preferably 0.5 to 10 parts by weight,
More preferably, it is 1 to 5 parts by weight.

Examples of the polymerization initiator include hydrogen peroxide, organic peroxides, persulfates, organic azo compounds, and redox-based polymerization initiators composed of these compounds, ferric sulfate, and sodium / formaldehyde / sulfoxylate. No. Specific examples of organic peroxides include dicumyl peroxide,
T-butylcumyl peroxide, bis- (t-butyl-peroxy-isopropyl) benzene, di-t-butyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butyl perbenzoate and the like. Can be Examples of the persulfate include ammonium persulfate, sodium persulfate and potassium persulfate. Specific examples of the organic azo compound include azobisisobutyronitrile and azobiscyclohexanenitrile. The amount of the polymerization initiator to be used is usually about 0.001 to 1 part by weight based on 100 parts by weight of the monomer, and may be appropriately adjusted at a desired reaction temperature so as to obtain a desired reaction rate. Good.

As the chain transfer agent, 2,4,4-trimethylpentane-2-thiol, 2,2,4,6,6-pentamethyl-heptane-4-thiol, 2,2,4,6, 6,8,8
Mercaptans such as -heptamethyl-nonane-4-thiol, t-dodecylmercaptan and t-tetradecylmercaptan; xanthogen disulfides such as dimethylxanthogen disulfide, diethylxanthogen disulfide and diisopropylxanthogen disulfide; tetramethylthiuram disulfide, tetraethylthiuram Thiuram disulfides such as disulfide and tetrabutylthiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; hydrocarbons such as pentaphenylethane; and terpinolene, α-terpinene, γ-terpinene, dipentene, α -Methylstyrene dimer (preferably having 50% by weight or more of 2-4-diphenyl-4-methyl-1-pentene), 2,5-dihydro Or the like can be given a run. These chain transfer agents can be used alone or in combination of two or more. The amount of the chain transfer agent is usually 3 parts by weight based on 100 parts by weight of the monomer mixture.
It is not more than 0.05 parts by weight, preferably 0.05 to 1 part by weight, more preferably 0.1 to 0.6 parts by weight.

The polymerization terminator is not particularly limited, but is a polymerization terminator having an amine structure, such as hydroxylamine, sodium dimethyldithiocarbamate, diethylhydroxyamine, hydroxyaminesulfonic acid and alkali metal salts thereof, which are conventionally used; Polymerization terminators having no amine structure, such as aromatic hydroxydithiocarboxylic acids such as hydroxydimethylbenzenedithiocarboxylic acid, hydroxydiethylbenzenedithiocarboxylic acid, and hydroxydibutylbenzenedithiocarboxylic acid; and alkali metal salts thereof; hydroquinone derivatives and catechol derivatives And the like. These polymerization terminators can be used alone or in combination of two or more. The amount of the polymerization terminator is not particularly limited, but is usually 0.1 to 10 parts by weight based on 100 parts by weight of the monomer.
Parts by weight.

As the anti-aging agent, 2,6-di-ter
t-butyl-4-methylphenol, 2,6-di-te
hindered phenol compounds such as rt-butyl-4-ethylphenol; hindered amine compounds such as diphenyl-p-phenylenediamine and N-isopropyl-N′-phenyl-p-phenylenediamine. The amount of the antioxidant used is usually about 0.05 to 5 parts by weight based on 100 parts by weight of the polymer produced by emulsion polymerization.

The ratio of the monomer to water (the weight ratio of monomer / water) during emulsion polymerization is usually 5/95 to 50/50, preferably 10/90 to 40/60, and more preferably. Is 20
/ 80 to 35/65. If the ratio of the monomer is high, a coagulated product is generated, and it is difficult to remove the heat of reaction. If the ratio is low, the productivity is poor. The polymerization temperature is usually -5 to 80C, preferably 0 to 60C, more preferably 3 to 30C, and particularly preferably 5 to 15C. If the polymerization temperature is low, the economy and productivity are poor, and if the polymerization temperature is high, the abrasion resistance and low heat build-up of the rubber crosslinked product are poor. The conversion when stopping the polymerization reaction is preferably 50 to 90%, more preferably 60 to 85%,
Particularly preferably, it is 65 to 80%. If the conversion is low, the productivity is inferior, and if it is high, the abrasion resistance and low heat generation of the crosslinked rubber are inferior.

When a conjugated diene rubber gel is produced by emulsion copolymerization, polymerization is carried out by a usual emulsion polymerization technique, and when a predetermined conversion is reached, a polymerization terminator is added to terminate the polymerization reaction. Then, if desired, after adding an antioxidant, the remaining monomers are removed by heating or steam distillation, etc., and a coagulant, a polymer flocculant or a heat-sensitive agent comprising an inorganic salt such as calcium chloride, sodium chloride, and aluminum sulfate. A coagulant used in ordinary emulsion polymerization such as a coagulant is added to coagulate and collect the latex. The recovered copolymer is washed with water and dried to obtain a desired conjugated diene rubber gel. When coagulating the latex, an extender oil may be added to obtain a latex.

Before coagulating the latex made of the conjugated diene rubber gel, a rubber latex having substantially no gel structure or a rubber gel latex other than the conjugated diene rubber gel in the present invention may be mixed, if desired. The rubber composition obtained by coagulating, collecting and drying this latex mixture contains a predetermined amount of a conjugated diene rubber gel.

The composition of the polymer obtained by the method for producing a conjugated diene rubber gel of the present invention varies depending on the composition of the charged monomer mixture and the conversion when the polymerization reaction is stopped.
This is because the reactivity of each monomer in emulsion copolymerization is usually different. However, the polymer composition can be adjusted by previously determining the composition of the charged monomer mixture and the conversion at the time of stopping the polymerization reaction. The polymer composition of the obtained conjugated diene rubber gel was analyzed by NMR,
It can be determined by employing infrared absorption spectrum analysis, ultraviolet absorption spectrum analysis, elemental analysis, analysis by refractive index measurement, or the like alone or in combination. However, in the case of a styrene-butadiene copolymer rubber gel having a small amount of divinylbenzene bonding units, it is very difficult to determine the amount of divinylbenzene bonding units,
The amount of the unreacted monomer in the polymerization reaction system after the termination of the polymerization can be measured and calculated from the value and the amount of the charged monomer.

The particle diameter of the conjugated diene rubber gel can be adjusted by the ratio of monomer / water, the type and amount of the emulsifier, the type and amount of the polymerization initiator, the polymerization temperature, and the like in the emulsion copolymerization. The toluene swelling index of the conjugated diene rubber gel is
The amount can be adjusted by the amount of the crosslinkable monomer, the amount of the chain transfer agent, the conversion at the time of terminating the polymerization, and the like. Thus, according to the production method of the present invention, a conjugated diene rubber gel having a desired toluene swelling index can be easily produced with high productivity.

Rubber Composition The rubber composition of the present invention comprises the aforementioned conjugated diene rubber gel,
That is, a conjugated diene rubber gel comprising 80 to 99% by weight of a conjugated diene monomer unit and 20 to 1% by weight of an aromatic vinyl monomer unit and having a toluene swelling index of 16 to 70, and a rubber capable of being crosslinked with sulfur. It is a composition containing.
The preferred copolymer composition and other properties of the conjugated diene rubber gel used in the rubber composition of the present invention are as described above for the conjugated diene rubber gel of the present invention.

The rubber which can be crosslinked with sulfur is not particularly limited, but usually a rubber containing a double bond corresponding to an iodine value of at least 2, preferably 5 to 470 is used. The iodine value is generally determined by adding iodine chloride in glacial acetic acid and expressed by the number of grams of iodine chemically bonded to 100 g of a certain substance. The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the rubber which can be crosslinked with sulfur is usually 10 to 150, preferably 20 to 120.

Specific examples of the rubber which can be crosslinked with sulfur include:
Natural rubber, synthetic polyisoprene, polybutadiene, alkyl acrylate-butadiene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isoprene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile -Partially hydrogenated butadiene copolymer, isobutylene-isoprene copolymer and ethylene-propylene
Diene copolymers, and mixtures thereof.
These rubbers may be oil-extended with an extension oil in advance. Above all, natural rubber, synthetic polyisoprene, styrene-butadiene containing 1 to 60% by weight, preferably 20 to 55% by weight, more preferably 25 to 50% by weight of styrene units produced by emulsion polymerization or solution polymerization are used. Polymer, high cis-1,4 bond content,
For example, polybutadiene having 90% by weight or more and a mixture thereof are preferable, and natural rubber, synthetic polyisoprene, a styrene-butadiene copolymer and a mixture thereof are particularly preferable.

The weight ratio of the conjugated diene rubber gel to the rubber capable of being crosslinked with sulfur in the rubber composition of the present invention is as follows:
1/99 to 50/50 is preferable, and 5/50 is more preferable.
95/40/60, particularly preferably 10 / 90-30 /
70. If the ratio of the conjugated diene rubber gel is small, the abrasion resistance of the cross-linked rubber is inferior.

The rubber composition of the present invention comprises a reinforcing material and necessary
Other compounding agents can be contained according to Reinforcement
As a material, carbon black and silica are compounded.
Is preferred. As carbon black,
Black, acetylene black, thermal black,
Channel black, graphite, etc. can be used
it can. Each of these carbon blacks
Or a combination of two or more
You. The specific surface area of carbon black is not particularly limited.
Is the nitrogen adsorption specific surface area (N _TwoThe lower limit of SA) is preferably
5m^Two/ G, more preferably 50m^Two/ G, upper limit is preferred
200m^Two/ G, more preferably 100 m^Two/ G
You. When the nitrogen adsorption specific surface area is within this range, the mechanical properties
It is preferable because it has excellent wear resistance. Also carb
Of dibutyl phthalate (DBP)
The lower limit is preferably 5 ml / 100 g, more preferably
Is 50 ml / 100 g, and the upper limit is preferably 400 ml / 100 g.
100 g, more preferably 200 ml / 100 g
You. If the DBP adsorption amount is in this range, mechanical characteristics
It is preferable because it has excellent properties and abrasion resistance.

Examples of the silica include, but are not particularly limited to, dry-process white carbon, wet-process white carbon, colloidal silica, and precipitated silica disclosed in JP-A-62-62838. Among these, wet-process white carbon containing hydrated silicic acid as a main component is preferable. Each of these silicas, alone,
Alternatively, two or more kinds can be used in combination.
The specific surface area of silica is determined by the nitrogen adsorption specific surface area (BET method).
In general, a material of 400 m ² / g or less is used. The nitrogen adsorption specific surface area is a value measured by the BET method according to ASTM D3037-81. The pH of silica is
Preferably, the pH is less than 7.0, and the pH is 5.0 to 6.0.
9 is more preferable.

When the rubber composition of the present invention contains silica as a reinforcing material, it is preferable to add a silane coupling agent since the low heat build-up and abrasion resistance are further improved. Although the silane coupling agent is not particularly limited, vinyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-
(Β-aminoethyl) -γ-aminopropyltrimethoxysilane, bis (3- (triethoxysilyl) propyl) tetrasulfide, bis (3- (triethoxysilyl) propyl) disulfide and the like, and JP-A-6-248
No. 116, tetrasulfides such as γ-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide and γ-trimethoxysilylpropylbenzothiazyltetrasulfide. From the viewpoint of avoiding scorch at the time of kneading, the silane coupling agent is preferably one containing four or less sulfur in one molecule.

These silane coupling agents can be used alone or in combination of two or more. The lower limit of the amount of the silane coupling agent relative to 100 parts by weight of silica is preferably 0.1 part by weight, more preferably 1 part by weight, particularly preferably 2 parts by weight, and the upper limit is preferably 30 parts by weight, more preferably 20 parts by weight. Parts, particularly preferably 10 parts by weight.

The lower limit of the compounding amount of the reinforcing material is the sum of the conjugated diene rubber gel and the rubber which can be crosslinked with sulfur (all rubber components).
For 100 parts by weight, preferably 10 parts by weight, more preferably 20 parts by weight, particularly preferably 30 parts by weight, and the upper limit is preferably 200 parts by weight, more preferably 150 parts by weight, particularly preferably 100 parts by weight. . In the rubber composition of the present invention, when silica and carbon black are used together as a reinforcing material, the mixing ratio thereof is appropriately selected according to the application and purpose, but the weight ratio of silica: carbon black is 10:90. ~ 99: 1, preferably 20: 80 ~
95: 5 is more preferable, and 30:70 to 90:10 is particularly preferable.

The rubber composition of the present invention may contain, in addition to the above components, a crosslinking agent, a crosslinking accelerator, a crosslinking activator, an antioxidant, an activator, a process oil, a plasticizer, a lubricant, a filler according to a conventional method. The compounding agents other than the reinforcing material such as the above can be contained in necessary amounts.

The crosslinking agent is not particularly limited, but sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur and highly dispersible sulfur; sulfur halide such as sulfur monochloride and sulfur dichloride; dicumyl peroxide And organic peroxides such as ditertiary butyl peroxide; quinone dioximes such as p-quinone dioxime and p, p'-dibenzoylquinone dioxime; triethylenetetramine, hexamethylenediaminecarbamate and 4,4'-methylenebis Organic polyvalent amine compounds such as -o-chloroaniline; alkylphenol resins having a methylol group; and the like. Of these, sulfur is preferred, and powdered sulfur is particularly preferred. These crosslinking agents are used alone or in combination of two or more.

The lower limit of the amount of the crosslinking agent to 100 parts by weight of the total rubber component is preferably 0.1 part by weight, more preferably 0.3 part by weight, particularly preferably 0.5 part by weight, and the upper limit is preferably 15 parts by weight. Parts, more preferably 10 parts by weight, particularly preferably 5 parts by weight. When the amount of the cross-linking agent is within this range, the composition is excellent in low heat build-up, mechanical properties and abrasion resistance.

Examples of the crosslinking accelerator include N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N- Sulfenamide-based cross-linking accelerators such as oxyethylene-2-benzothiazolesulfenamide and N, N'-diisopropyl-2-benzothiazolesulfenamide; guanidines such as diphenylguanidine, dioltotolylguanidine, and orthotolylbiguanidine Thiourea-based crosslinking accelerators such as diethylthiourea; thiazole-based crosslinking accelerators such as 2-mercaptobenzothiazole, dibenzothiazyldisulfide, and 2-mercaptobenzothiazole zinc salt; tetramethylthiuram monosulfite Thiuram-based cross-linking accelerators such as sodium chloride and tetramethylthiuram disulfide; dithiocarbamic acid-based cross-linking accelerators such as sodium dimethyldithiocarbamate and zinc diethyldithiocarbamate; Crosslinking accelerator; and the like.

These crosslinking accelerators may be used alone,
Alternatively, two or more of them are used in combination, and those containing a sulfenamide-based crosslinking accelerator are particularly preferred. The lower limit of the amount of the crosslinking accelerator relative to 100 parts by weight of the total rubber component is preferably 0.1 part by weight, more preferably 0.3 part by weight, particularly preferably 0.5 part by weight, and the upper limit is preferably 15 parts by weight. More preferably, it is 10 parts by weight, particularly preferably 5 parts by weight.

The crosslinking activator is not particularly limited, but higher fatty acids such as stearic acid and zinc oxide can be used. As zinc oxide, it is preferable to use one having a high surface activity and a particle size of 5 μm or less,
Active zinc white having a particle size of 0.05 to 0.2 μm and 0.3 to 0.3 μm
One example is zinc white of 1 μm. As the zinc oxide, a zinc oxide surface-treated with an amine-based dispersant or wetting agent can be used.

These crosslinking activators can be used alone or in combination of two or more.
The mixing ratio of the crosslinking activator is appropriately selected depending on the type of the crosslinking activator. The lower limit of the amount of the higher fatty acid added to 100 parts by weight of the total rubber component is preferably 0.05 part by weight, more preferably 0.1 part by weight, particularly preferably 5 parts by weight,
The upper limit is preferably 15 parts by weight, more preferably 10 parts by weight, particularly preferably 5 parts by weight. All rubber components 10
The lower limit of the amount of zinc oxide to 0 parts by weight is preferably 0.05 parts by weight, more preferably 0.1 parts by weight, particularly preferably 0.5 parts by weight, and the upper limit is preferably 10 parts by weight.
It is more preferably 5 parts by weight, particularly preferably 2 parts by weight. When the compounding amount of the crosslinking activator is within this range, the unvulcanized rubber composition is excellent in processability, mechanical properties, abrasion resistance, and the like, which is preferable.

Further, for example, diethylene glycol,
Activators such as polyethylene glycol and silicone oil having a functional group such as an epoxy group or an alkoxysilyl group; fillers such as calcium carbonate, talc, and clay; and waxes.

The rubber composition of the present invention contains at least one monomer selected from epichlorohydrin, ethylene oxide, propylene oxide and allyl glycidyl ether, which has no conjugated diene unit, as long as the effects of the present invention are not impaired. Monomeric homopolymer or copolymer,
Acrylic rubber, fluorine rubber, silicone rubber, ethylene-
It may contain propylene rubber and urethane rubber.

The rubber composition of the present invention can be obtained by kneading each component according to a conventional method. For example, a rubber composition can be obtained by kneading a compounding agent excluding a crosslinking agent and a crosslinking accelerator and a rubber component, and then mixing the kneaded product with a crosslinking agent and a crosslinking accelerator. The lower limit of the kneading temperature of the compounding agent and the rubber component excluding the crosslinking agent and the crosslinking accelerator is preferably 80 ° C, more preferably 100 ° C, particularly preferably 120 ° C, and the upper limit is preferably 200 ° C, more preferably 190 ° C, particularly Preferably it is 180 ° C. The lower limit of the kneading time of the compounding agent excluding the crosslinking agent and the crosslinking accelerator and the rubber component is preferably 30 seconds, more preferably 1 minute, and the upper limit is preferably 30 minutes.
Minutes. Mixing of a crosslinking agent and a crosslinking accelerator is usually performed at 100 ° C.
After that, it is preferably carried out after cooling to 80 ° C. or less.

The rubber composition of the present invention is usually used as a rubber crosslinked product. The crosslinking method is not particularly limited, and may be selected according to the shape and size of the crosslinked product. The mold may be filled with the crosslinkable rubber composition and heated to perform crosslinking at the same time as molding. Alternatively, a previously molded uncrosslinked rubber composition may be heated to perform crosslinking. The crosslinking temperature is preferably from 120 to 200C, more preferably from 140 to 18C.
0 ° C., and the crosslinking time is usually about 1 to 120 minutes. The crosslinked product of the rubber composition can be used, for example, as a component such as a tire, a cable coating agent, a hose, a transmission belt, a conveyor belt, a roll cover, a shoe sole, a sealing ring, and an anti-vibration rubber, and is particularly suitable as a tire material. Can be used for

[0060]

EXAMPLES The present invention will be specifically described below with reference to examples. Parts and% in Production Examples, Examples and Comparative Examples are based on weight unless otherwise specified. The properties of the rubber raw material component, the rubber composition, and the crosslinked rubber were measured as follows.

(1) Particle size of rubber gel particles: A latex of a conjugated diene rubber gel diluted with water so as to have a solid concentration of about 0.01% was dropped on a mesh for observation with a transmission electron microscope. Thereafter, the sample was stained and fixed with osmium tetroxide vapor, and then water was evaporated to obtain an observation sample. Observed sample was observed with a transmission electron microscope.
Observation was performed at a magnification of up to 50,000 times, the diameter (unit: nm) of 100 particles was measured, and the weight average particle diameter was determined from the value. (2) Styrene unit amount: The styrene unit amount bound in the copolymer was measured according to JIS K 6383. However, in a copolymer obtained by copolymerizing divinylbenzene, the bound divinylbenzene unit is also included in the styrene unit amount in the measurement.

(3) Toluene swelling index: 250 mg of a sample rubber is shaken in 25 ml of toluene for 24 hours to swell. The swollen gel was centrifuged to 43
The mixture was centrifuged under a centrifugal force of 000 m / sec ² , and the swollen gel was weighed in a wet state, then dried at 70 ° C. until a constant weight was obtained, and the dried gel was weighed again. The toluene swelling index was determined as the weight of the gel in a wet state / the weight of the gel after drying. (4) Mooney viscosity: Mooney viscosity of raw rubber (ML
_{1 + 4} , 100 ° C.) was measured according to JIS K 6300.

(5) Mechanical Properties of Crosslinked Rubber: The tensile strength and elongation of the crosslinked rubber were measured according to JIS K6301. (6) Abrasion resistance index: A pico abrasion test was performed in accordance with JIS K 6264, and each was represented by an index with Comparative Example 1 being 100. The higher the wear resistance index, the better the wear resistance. (7) Low heat build-up: RDA-I manufactured by Rheometrics
Using I, tan δ at 60 ° C. was measured under the conditions of 0.5% twist and 20 Hz. When this tan δ (60 ° C.) value is small, it indicates that the heat generation is excellent. In addition, Comparative Example 1 is indicated by an index with 100, and a large index indicates that the heat generation is excellent.

Example 1 Preparation of Conjugated Diene Rubber Gel I In a pressure-resistant reaction vessel, a total of 4.5 parts of water and disproportionated potassium rosinate and sodium fatty acid as emulsifiers were added.
Parts, 0.1 part of potassium chloride, a monomer mixture shown in Table 1 and a chain transfer agent (t-dodecylmercaptan), and the mixture was stirred and the internal temperature was adjusted to 12 ° C. 0.1 part of oxide,
Sodium formaldehyde sulfoxylate 0.2
And 0.01 part of ferric sulfate was added to initiate the polymerization reaction. After the reaction was continued at 12 ° C. until the polymerization conversion reached 70%, 0.1 part of diethylhydroxylamine was added to terminate the polymerization. A part of the latex after the termination of the polymerization was sampled, subjected to gas chromatography analysis, and the amount of each unreacted monomer was determined based on a previously prepared calibration curve. From the amounts of the unreacted monomers and the amounts of the charged monomers determined as described above, the amounts of the monomer units constituting the copolymer were determined. Table 1 shows the results.

Next, after heating and recovering the remaining monomer by steam distillation at about 70 ° C. under reduced pressure, 2 parts of an antioxidant (2,6 -Di-tert-butyl-4-methylphenol) was added. A part of the obtained latex was extracted and its weight average particle diameter was measured. Table 1 shows the results. Next, the obtained latex was added to a sodium chloride / sulfuric acid solution and coagulated. The produced crumb was taken out, washed sufficiently with water, and dried under reduced pressure at 50 ° C. to obtain a conjugated diene rubber gel I. Table 1 shows the styrene unit amount and the toluene swelling index of the conjugated diene rubber gel I.

Examples 2 to 6 Conjugated Diene Rubber Gel II
-VI Preparation of conjugated diene rubber gel II in the same manner as in Example 1 using a monomer mixture having the composition shown in Table 1 and a chain transfer agent
~ VI. Table 1 shows the respective characteristic values.

Example 7 Conjugated Diene Rubber Gel VII
Using a monomer mixture having the composition shown in Production Table 1, the reaction temperature was set to 50 ° C., and the radical polymerization initiator was changed to potassium persulfate (0.2).
Conjugated diene rubber gel V in the same manner as in Example 1 except that the conversion rate was 92% when the polymerization reaction was stopped.
II was obtained. Table 1 shows the respective characteristic values. The conjugated diene rubber gels I to VII shown in Examples 1 to 7 are:
Almost no rubber component soluble in toluene.

Comparative Production Example 1 Production of Conjugated Diene Rubber I A conjugated diene rubber I was obtained in the same manner as in Example 1 except that a monomer mixture having the composition shown in Table 1 was used. Table 1 shows the styrene unit amount and Mooney viscosity of this rubber. In addition, the toluene swelling index of the conjugated diene rubber I was not measured as a significant value because it did not substantially contain a gel.

[0069]

[Table 1]

As shown in Examples 1 to 7 of Table 1, according to the method for producing a conjugated diene rubber gel of the present invention, a conjugated diene rubber having a desired polymer composition and a toluene swelling index can be easily obtained with good productivity. It can be seen that a rubber gel is obtained.
On the other hand, in order to produce a conjugated diene rubber gel having a desired toluene swelling index from the conjugated diene rubber latex having no gel structure shown in Comparative Production Example 1, the residual monomer was obtained from the latex after termination of polymerization. , A step of performing a heat treatment by further adding a peroxide is required.

Examples 8 to 11, Comparative Examples 1 to 4 Rubber Crosslinking
Preparation and evaluation of product 100 parts in total of rubber components shown in Table 2, 40 parts of carbon black (SEAST SO, manufactured by Tokai Carbon Co., Ltd.), 3 parts of zinc oxide, 2 parts of stearic acid and N- (1, 3-dimethylbutyl) -N'-phenyl-p
-2 parts of phenylenediamine were kneaded with a Banbury mixer at 120 ° C for 6 minutes. Then, the obtained kneaded material, 1.1 parts of sulfur and 0.9 part of Nt-butyl-2-benzothiazylsulfenamide as a crosslinking accelerator were kneaded with an open roll at 50 ° C. to obtain a rubber. A composition was obtained. This rubber composition was press-crosslinked at 160 ° C. for 12 minutes to obtain a rubber crosslinked product. Table 2 shows the measurement results of physical properties of the rubber crosslinked product.

As shown in Table 2, the rubber crosslinked product using the conjugated diene rubber gel having a small amount of styrene unit in Comparative Example 2 was inferior in abrasion resistance. The rubber crosslinked product using the conjugated diene rubber gel having a large amount of styrene units in Comparative Example 3 is inferior in low heat generation. The rubber cross-linked product using the conjugated diene rubber gel having a small toluene swelling index of Comparative Example 4 has significantly reduced elongation and poor abrasion resistance. Compared with these, the crosslinked rubber products of Examples 8 to 11 of the present invention are excellent in wear resistance and low heat generation without impairing the mechanical properties. Comparing Example 9 with Example 11, emulsion polymerization was carried out at a lower temperature.
The rubber crosslinked product of Example 9 using a conjugated diene rubber gel produced by stopping the polymerization reaction at a conversion of 0% is more excellent.

[0073]

[Table 2]

[0074]

The novel conjugated diene rubber gel of the present invention provides a rubber composition having excellent wear resistance and low heat build-up without impairing mechanical properties. This conjugated diene rubber gel and a crosslinked product of a rubber composition containing a rubber capable of being crosslinked with sulfur show excellent abrasion resistance and low heat generation while maintaining good mechanical properties. Particularly, it is suitable as a constituent member of a sidewall, a bead, and an undertread. According to the emulsion copolymerization method of the present invention,
A conjugated diene rubber gel containing the above conjugated diene rubber gel and having a toluene swelling index of 70 or less can be easily obtained with high productivity.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 AC01X AC03X AC06X AC07X AC08W AC08X AC11X BB15X FD019 FD149 FD159 GM00 GM01 GN01 GQ01 4J011 KA02 KB02 KB04 KB29 4J100 AA02R AA03R AA04AB ABQ AB02 AB02A AJ09R AL03R AL04R AL08R AL09R AL10R AL34R AL36R AL44R AL62S AL75S AM02R AM05R AM15R AM19R AM21R AM48S AP02S AQ12R AR04R AR11R AS02P AS04P AS06P BA03R BA05R BA06R BA20R BA31R CA23S BB01 BC03R03

Claims (5)

[Claims] 1. 80 to 99% by weight of a conjugated diene monomer unit
And a conjugated diene rubber gel comprising 20 to 1% by weight of an aromatic vinyl monomer unit and having a toluene swelling index of 16 to 70. 2. A conjugated diene monomer unit of 80 to 99% by weight, an aromatic vinyl monomer unit of 1 to 20% by weight, another ethylenically unsaturated monomer unit of 0 to 19% by weight, and a crosslinkable unit. A conjugated diene rubber gel comprising a monomer unit of 0 to 1.5% by weight and having a toluene swelling index of 16 to 70. 3. 80 to 99% by weight of a conjugated diene monomer unit
A rubber composition comprising a conjugated diene rubber gel comprising 20 to 1% by weight of an aromatic vinyl monomer unit and having a toluene swelling index of 16 to 70, and a rubber crosslinkable with sulfur. 4. A conjugated diene monomer unit of 80 to 99% by weight, an aromatic vinyl monomer unit of 1 to 20% by weight, another ethylenically unsaturated monomer unit of 0 to 19% by weight, and a crosslinkable unit. A rubber composition comprising a conjugated diene rubber gel having a monomer unit of 0 to 1.5% by weight and having a toluene swelling index of 16 to 70, and a rubber which can be crosslinked with sulfur. 5. A conjugated diene monomer in an amount of 50 to 99.9% by weight, an aromatic vinyl monomer in an amount of 0 to 30% by weight, other ethylenically unsaturated monomer units in an amount of 0 to 20% by weight, and a crosslinkable monomer. A method for producing a conjugated diene rubber gel having a toluene swelling index of 70 or less, characterized by emulsion-copolymerizing a monomer mixture comprising 0.1 to 20% by weight of a monomer.