WO2003072650A1

WO2003072650A1 - Polymer composition, rubber composition, vulcanizable rubber composition, and vulcanizate thereof

Info

Publication number: WO2003072650A1
Application number: PCT/JP2003/002254
Authority: WO
Inventors: Shigeru Fujita; Takashi Toya
Original assignee: Zeon Corporation
Priority date: 2002-02-28
Filing date: 2003-02-27
Publication date: 2003-09-04
Also published as: JP4007019B2; JP2003253048A

Abstract

A polymer composition which comprises 100 parts by weight of a nitrile copolymer rubber (A) having an iodine value of 100 or lower and 10 to 150 parts by weight of particles (B) having an average particle diameter of 10 µm or smaller which are made of a methyl methacrylate homopolymer or a copolymer comprising at least 50 wt.% methyl methacrylate units; a rubber composition obtained by heating the polymer composition at a temperature higher by at least 20°C than the glass transition temperature (Tg) of the polymer constituting the particles (B); and a vulcanizable rubber composition obtained by incorporating a vulcanizing agent into the rubber composition. The vulcanizable composition gives a rubber vulcanizate excellent in ozone resistance and reduced in compression set.

Description

Description Polymer composition, rubber composition, vulcanizable rubber composition, and vulcanizate thereof

The present invention relates to a rubber vulcanizate having excellent ozone resistance and low compression set. More specifically, a polymer composition comprising a nitrile group-containing copolymer rubber and a methacrylate polymer; a rubber composition obtained by heat-treating the polymer composition; The present invention relates to a vulcanizable rubber composition containing an agent, and a vulcanizate obtained by vulcanizing the vulcanizable rubber composition, which has excellent ozone resistance and low compression set. Background art

Acrylonitrile-butadiene copolymer rubber (hereinafter referred to as “NBR”) is a typical rubber used in various applications requiring oil resistance. NBR has a problem that it has poor ozone resistance due to its unsaturated bond in the molecule, and deteriorates quickly unless an antiozonant is added.

The ozone deterioration inhibitor prevents the rubber from deteriorating by reacting with radicals generated by ozone before reacting with the rubber molecules. As a result, the anti-aging agent itself deteriorates due to ozone, and its function is lost. Therefore, even though the ozone deterioration inhibitor can delay the deterioration of rubber molecules, it cannot completely prevent it, and it is difficult to maintain the ozone resistance for a long time.

Hydrogenated NBR improves ozone resistance by reducing unsaturated bonds due to hydrogenation. However, it is not enough, and it is necessary to add an antiozonant like NBR.

A blend of NBR and vinyl chloride resin (US Pat. No. 2,330,353) developed to improve the ozone resistance of NBR has excellent ozone resistance and oil resistance It is widely used as an automobile part, mainly for fuel hoses. However, this blend did not provide a vulcanizate with sufficiently low compression set. In addition, vinyl chloride resin can release halogens upon disposal, which can cause environmental problems. Therefore, new materials other than the above blends are required. Have been.

Examples of such materials include blends of NBR and various halogen-free thermoplastic resins, for example, polyamide resins (Shinichiro Goto, Journal of The Rubber Society of Japan, Vol. 73, pp. 247, 2000) ), Polypropylene resin (Hiroichi Iino, Journal of the Rubber Society of Japan, Vol. 38, p. 7, Ί965), styrene-acrylonitrile copolymer resin (Toshio Nishi, Journal of The Rubber Association of Japan, Vol. 68, 8) (Page 34, 1995)), but all of the vulcanizates had insufficient ozone resistance.

Recently, a blend of NBR and a vinyl-based resin having a crosslinkable functional group has been proposed (Japanese Patent Application Laid-Open No. 2002-222658). According to this proposal, a vulcanized product of a blend of NBR and a methyl methacrylate polymer has poor ozone resistance, whereas a vulcanized product of a blend of NBR and a methacrylic acid-modified methyl methacrylate polymer is poor. Shows that it has excellent ozone resistance. However, the demand for rubber vulcanizates with better ozone resistance is not sufficient, and new materials are required. Disclosure of the invention

Accordingly, an object of the present invention is to provide a nitrile group-containing copolymer rubber material having excellent ozone resistance and low compression set.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, obtained a polymer composition containing a low iodine value-containing tributyl group-containing copolymer rubber and a particulate methyl methacrylate polymer under specific conditions. It has been found that a rubber material having excellent ozone resistance and a small compression set can be obtained by heat treatment, and the present invention has been completed based on this finding. Thus, according to the present invention, (1) 100 parts by weight of a nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less, and a single weight of methyl methacrylate having an average particle diameter of 10 m or less. Copolymer particles containing 50% by weight or more of a united or methyl methacrylate unit (B) A polymer composition containing 10 to 50 parts by weight of a copolymer;

(2) A rubber composition obtained by heat-treating the polymer composition at a temperature at least 20 ° C higher than the glass transition temperature of the homopolymer or copolymer of methyl methacrylate constituting the particles (B) object;

(3) A vulcanizing agent is further added to the polymer composition (1) or the rubber composition (2). Vulcanizable rubber composition comprising; and,

(4) A rubber vulcanizate obtained by vulcanizing the vulcanizable rubber composition is provided. BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present invention will be described in more detail.

The polymer composition of the present invention comprises 100 parts by weight of a nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less, and methyl methacrylate alone having an average particle diameter of 1 μμηη or less. Polymer or copolymer containing 50% by weight or more of methyl methacrylate units (hereinafter, these methyl methacrylate homopolymers and copolymers may be collectively referred to as “methyl methacrylate polymer J” ) (B) in an amount of 10 to 150 parts by weight.

The nitrile group-containing copolymer rubber (A) used in the present invention is a rubber obtained by copolymerizing an α,) 8-ethylenically unsaturated nitrile monomer with another monomer. The content of the) 3-ethylenically unsaturated ditolyl monomer unit is preferably from 10 to 60% by weight, more preferably from 12 to 55% by weight, and particularly preferably from 15 to 55% by weight. ~ 50% by weight. If the content of a, j8-ethylenically unsaturated ditolyl monomer units is too small, the resulting rubber vulcanizate will have poor oil resistance, and if too large, will have poor cold resistance.

Further, the iodine value of the copolymer rubber (II) containing a nitrile group is 100 or less, preferably 80 or less, more preferably 60 or less. If the iodine value is too large, the rubber vulcanizate has poor oil resistance and ozone resistance.

Examples of the α,) 8-ethylenically unsaturated nitrile monomer include acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile, among which acrylonitrile is preferable.

In the nitrile group-containing copolymer rubber (Α), the monomers to be copolymerized with a,) 8-ethylenically unsaturated ditolyl monomer include conjugated gen monomers and non-conjugated gen monomers. , Α-year-old refin and the like.

Examples of the conjugated diene monomer include 3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene, and among them, 1,3-butadiene is preferable. The non-conjugated diene monomer preferably has 5 to 12 carbon atoms, such as 1,4-pentadiene, 1,4-hexadiene, vinylnorbornene, Examples include dicyclopentadiene. As the α-olefin, those having 2 to 12 carbon atoms are preferred, and examples thereof include ethylene, propylene, 1-butene, 4-methyl-11-pentene, 1-1-hexene, and 1-octene.

Further, aromatic vinyl monomers, fluorine-containing vinyl monomers, 0 !,) 8-ethylenically unsaturated monocarboxylic acids, α,) 8-ethylenically unsaturated polycarboxylic acids or anhydrides, A polymerizable antioxidant may be copolymerized.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyl pyridine and the like. Examples of fluorine-containing vinyl monomers include, for example, full-year-old vinyl ether, full-year-old vinylpropyl ether, 0-trifur-year-old lomethylstyrene, pentaful-year-old vinyl benzoate, difluoro-ethylene, tetrafur-year-old ethylene, etc. Is mentioned. Examples of the 0 !,) 8-ethylenically unsaturated monocarboxylic acid include acrylic acid and methacrylic acid. α, —Ethylenically unsaturated polycarboxylic acids include, for example, itaconic acid, fumaric acid, maleic acid and the like.

Examples of the / 3-ethylenically unsaturated polycarboxylic anhydride include itaconic anhydride and maleic anhydride. Examples of the copolymerizable antioxidant include Ν— (4-anilinophenyl) acrylamide, Ν— (4-anilinophenyl) methacrylamide, Ν— (4-anilinophenyl) cinnamamide, Ν— (4-anilinophenyl) ) Crotonamide, Ν-phenyl 41- (3-vinylbenzyloxy) aniline, Ν-phenyl-41- (4-vinylbenzyloxy) aniline and the like.

The monomer copolymerized with the 8-ethylenically unsaturated ditolyl monomer may be used alone or in combination of two or more. The amount of these monomer units is preferably 40 to 90% by weight, more preferably 45 to 88% by weight, and particularly preferably 5 to 90% by weight, based on the weight of the nitrile group-containing copolymer rubber (II). 0 to 85% by weight.

Therefore, preferred nitrile group-containing copolymer rubber (Α) is a copolymer of acrylonitrile and 1,3-butadiene and a hydrogenated product thereof, and acrylonitrile unit is 10 to 60% by weight, more preferably 1 to 60% by weight. 2 to 55% by weight, particularly preferably 15 to 50% by weight, and at least one unit selected from 1,3-butadiene unit and its hydrogenated unit 40 to 90% by weight, more preferably Is a copolymer containing 45 to 88% by weight, particularly preferably 50 to 85% by weight. The nitrile group-containing copolymer rubber (A) has a halogen content of preferably from 0.5 to 0.5% by weight, more preferably from 0 to 0.1% by weight, particularly preferably 0% by weight.

Two Bok厶one hundred twenty-one viscosity Lil group-containing copolymer rubber _{(A) (ML 1 + 4} , 100 ° C) is preferably 1 0-3 0 0, more preferably 2 0-2 5 0, particularly preferably Is 30 to 200. If the Mooney viscosity is too low, the mechanical properties of the rubber vulcanizate may be inferior, while if too high, the processability may be inferior.

The method for producing the nitrile group-containing copolymer rubber (A) is not particularly limited, and the monomer mixture may be copolymerized according to a known emulsion polymerization method or the like. If the iodine value of the resulting copolymer rubber containing a nitrile group (A) is too large, the unsaturated bonds in the main chain are saturated by performing a normal hydrogenation treatment to reduce the iodine value. I just need.

The methyl methacrylate polymer constituting the particles (B) contains 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight of a single polymer of methyl methacrylate or a monomer unit of methyl methacrylate. % Of methyl methyl acrylate. The methyl methacrylate polymer preferably does not substantially contain halogen. The halogen content is preferably 0.5% by weight or less, more preferably 0.1% by weight or less, particularly preferably 0% by weight.

The methyl methacrylate polymer preferably has a glass transition temperature of at least 80 ° C, more preferably at least 90 ° C, particularly preferably at 100 to 150 ° C. The methyl methacrylate polymer may be a methyl methacrylate homopolymer or a copolymer of methyl methacrylate and another monomer copolymerizable therewith. The monomer to be copolymerized is not particularly limited, but a monomer that does not introduce an unsaturated bond into the polymer main chain is preferable, and a monomer that does not have a crosslinkable functional group is preferable. Further, it is preferable that the copolymerizable monomer contains substantially no halogen.

Examples of such monomers include methacrylate monomers other than methyl methacrylate, acrylate monomers, aromatic vinyl monomers, ethylenically unsaturated nitrile monomers, and vinyl ester monomers. And vinyl ether monomers. Examples of the methyl methacrylate monomer include ethyl methacrylate, propyl methacrylate, butyl methacrylate, isoptyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and octyl methacrylate. . Acrylic ester Monomers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isoptyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate. No. Examples of the aromatic vinyl monomer include styrene, vinyltoluene, and α-methylstyrene. Examples of the ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile. Examples of the vinyl ester monomer include vinyl acetate and vinyl propionate. Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, and hydroxybutyl vinyl ether. Of these, methacrylate monomers other than methyl methacrylate and ethylenically unsaturated ditolyl monomers are preferred, and ethyl methacrylate, propyl methacrylate, butyl methacrylate and acrylonitrile are particularly preferred.

The monomers copolymerized with methyl methacrylate can be used alone or in combination of two or more. The amount of these monomer units is 50% by weight or less, preferably 30% by weight or less, more preferably 10% by weight or less, based on the weight of the methyl methacrylate polymer.

It is preferable that the methyl methacrylate polymer does not substantially contain a crosslinkable functional group. That is, the content of the monomer unit containing a crosslinking functional group in the methyl methacrylate polymer is preferably 0.01 equivalent or less, more preferably 0.1 equivalent, per 100 g of the polymer as a functional group. It is not more than 0.05 equivalent, and particularly preferably does not contain a crosslinkable functional group. The crosslinkable functional group is a group that reacts with a crosslinking agent or another crosslinkable functional group by heating to cause crosslinking between molecules of the polymer. Specific examples include an epoxy group, a carboxyl group, an acid anhydride group, an amino group, an imino group, an amide group, and a hydroxy group. Examples of these crosslinkable functional groups include those obtained by copolymerizing and introducing a monomer having a crosslinkable functional group such as acrylic acid and methacrylic acid, and having an acid anhydride group such as maleic anhydride. A monomer is copolymerized, and then an acid anhydride group is modified into a carboxyl group by hydrolysis and then introduced.The addition reaction is performed after polymerization such as addition of maleic anhydride by Diels-Alder reaction. Includes those that have been re-introduced.

If the amount of crosslinkable functional groups in the methyl methacrylate polymer is large, the methyl methacrylate polymer undergoes a cross-linking reaction between molecules during the heat treatment, so that particles of the methyl methacrylate polymer It becomes difficult to finely disperse (B) in the matrix of the ditriol group-containing copolymer rubber (A), and the resulting rubber vulcanizate may have poor ozone resistance. In contrast, when the methyl methacrylate polymer does not substantially contain a crosslinkable functional group, the particles of the methyl methacrylate polymer (B) are contained in the matrix of the ditriol group-containing copolymer rubber (A). ) Are finely dispersed, and the ozone resistance of the rubber vulcanizate is improved.

The average molecular weight of the methyl methacrylate polymer is not particularly limited, but the weight average molecular weight in terms of standard polystyrene measured by gel permeation 'chromatography (GPC) is preferably 50,000 to 4,000,000, It is more preferably 100,000 to 2,000,000, particularly preferably 200,000 to 1,000,000. If the weight average molecular weight is too small, the ozone resistance of the rubber vulcanizate may decrease. Conversely, if the weight average molecular weight is too high, moldability may be poor. The average particle size of the particles (B) of the methyl methacrylate polymer used in the present invention is 1 or less, preferably from 0.0 to 5 ^ ιη, more preferably from 0.05 to 2 im. If the particle size is extremely small, it is difficult to produce, and conversely, if the particle size is too large, the ozone resistance of the vulcanizate may be reduced.

The method for producing the particles (B) of the methyl methacrylate polymer is not particularly limited. However, when the particles are produced by emulsion polymerization or suspension polymerization, the particle diameter can be controlled by the polymerization conditions. In addition, the particles (B) of the methyl methacrylate polymer in a lump state such as pellets are pulverized by a pulverizer such as a jet air pulverizer, a mechanical collision pulverizer, a roll mill, a hammer mill, or an impeller breaker. Then, the obtained ground material is introduced into a classifier such as an air classifier or a sieve classifier to classify the particles, thereby controlling the particle size.

The polymer composition of the present invention comprises 10 to 150 parts by weight, preferably 15 to 15 parts by weight of particles (B) of a methyl methacrylate polymer based on 100 parts by weight of a copolymer having a nitrile group (A). -100 parts by weight, more preferably 20-80 parts by weight. If the amount of the methyl methacrylate polymer particles (B) is too small, the ozone resistance is poor, while if it is too large, the rubber elasticity is lost and the compression set becomes large.

The method for producing the polymer composition of the present invention is not particularly limited, and the nitrile group-containing copolymer rubber (A) and the particles of the methyl methacrylate polymer (B) are mixed in the following manner using a usual kneader. The mixture is mixed at a temperature lower than the heat treatment temperature, and is mixed with the nitrile group-containing copolymer rubber (A). A dry blending method in which the polymer (B) is dispersed while maintaining its particle size, or a latex coprecipitation method in which both components are mixed in a latex state and then coagulated and dried at a temperature lower than the heat treatment temperature described below. A publicly known method such as the above can be used. It is necessary that the particles (B) of the methyl methacrylate polymer be present in the obtained polymer composition while maintaining the original particle form. If the particle morphology is lost, it becomes difficult to further reduce the particle size of the particles of the methyl methacrylate polymer (B) in the heat treatment.

The polymer composition includes a reinforcing agent such as carbon black and silica, a filler such as calcium carbonate and talc, which are not changed by heating when the polymer composition is heat-treated to prepare the following rubber composition; A compounding agent generally used in the rubber field, such as an antioxidant, may be added. These compounding agents are preferably compounded after the polymer composition is subjected to heat treatment. Further, a polymer other than the rubber polyacrylate polymer (B) other than the nitrile group-containing copolymer rubber (A) may be blended as long as the effects of the present invention are not impaired.

The rubber composition of the present invention can be obtained by subjecting the above polymer composition of the present invention to a heat treatment at a temperature at least 20 ° C. higher than the glass transition temperature (T g) of the methyl methacrylate polymer. More specifically, when the methyl methacrylate polymer is a non-crystalline polymer, its temperature is at least 20 ° C higher than its glass transition temperature (T g) to 300 ° C, more preferably ( The heat treatment is performed in a temperature range of (Tg + 30) ° C to 300 ° C, particularly preferably (Tg + 40) ° C to 280 ° C. Further, when the methyl methacrylate polymer is a crystalline polymer, it is preferably produced by a heat treatment in a range from a temperature at least 20 ° C. higher than its glass transition temperature (T g) to a melting temperature. I do.

If the heat treatment temperature is too low, the particle size of the methyl methacrylate polymer particles (B) in the matrix of the nitrile group-containing copolymer rubber (A) is unlikely to be small, and the rubber vulcanizates are resistant to zoning. Poor sex. Conversely, if the heat treatment temperature is too high, the nitrile group-containing copolymer rubber (A) is thermally degraded, and the rubber vulcanizate may have poor strength or ozone resistance.

The heat treatment method is not particularly limited, but an extruder such as a single-screw extruder or a twin-screw extruder; a closed kneader such as a kneader, Banbury, an internal mixer; a kneader such as a roll kneader; And the like. The heating time is preferably 1 to 30 minutes.

The vulcanizable rubber composition of the present invention further comprises the above-mentioned polymer composition or rubber composition, It contains a sulfuric acid.

Examples of the vulcanizing agent include, but are not particularly limited to, sulfur-based vulcanizing agents and organic peroxides.

Examples of the sulfur-based vulcanizing agent include sulfur such as powdered sulfur and precipitated sulfur; and organic such as 4,4′-dithiomorpholine, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and high molecular polysulfide. And sulfur compounds (sulfur donating compounds). Examples of the organic peroxide include dialkyl peroxides, disilver peroxides, and peroxyxesters. Dialkyl peroxides include, for example, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (t-butyl-propyl) -3-hexyne, 2,5- Examples include dimethyl-1,2,5-di (t-butylaminopropyl) hexane and 1,3-bis (t-butylaminopropylisopropyl) benzene. Examples of disilver oxide include benzoyl peroxide, isobutyryl peroxide, and the like. Examples of the peroxyxester include 2,5-dimethyl-2,5-bis (benzoylpa1xoxy) hexane and t-butylx1xisopropylisopropyl.

When the nitrile group-containing copolymer rubber (A) has a crosslinkable functional group, any known vulcanizing agent (crosslinking agent) that reacts with the functional group can be used. In the case of a group, a polyamine-based vulcanizing agent is preferred.

Polyamine vulcanizing agent is a compound having two or more amino groups, amino groups or hydrazide structures more hydrogens aliphatic hydrocarbon Motoya aromatic hydrocarbons, i.e., the structure represented in one CONHNH ₂ It has been replaced.

Examples of the polyamine vulcanizing agent include aliphatic polyamines, aromatic polyamines, and compounds having two or more hydrazide structures. Examples of the aliphatic polyvalent amines include hexamethylene diamine, hexamethylene diamine power rubamate, tetramethylene penmin, hexamethylene diamine-cinnamaldehyde adduct, and hexamethylene diamine. —Dibenzoate salts and the like. Examples of the aromatic polyamines include 4,4'-methylenedianiline, 4,4'-one-year-old xydiphenylamine, m-phenylenediamine, P-phenylenediamine, 4,4'-methylenebis (0 — black Lower nitrine) and the like. Examples of the compound having two or more hydrazide structures include isophthalic dihydrazide, adipic dihydrazide, and sebacic dihydrazide.

The amount of the vulcanizing agent varies depending on the type of the vulcanizing agent and is not particularly limited, but is usually 0.1 to 10 parts by weight based on 100 parts by weight of the nitrile group-containing copolymer rubber (A). It is used in an amount that satisfies the properties required for vulcanizates and vulcanizates within the range of. If the amount of the vulcanizing agent is too small, the crosslink density becomes low and the compression set becomes large. Conversely, if the amount is too large, the bending fatigue resistance is poor.

When a sulfur vulcanizing agent is used, a vulcanization accelerator, activator and vulcanization accelerator are usually used together. Vulcanization accelerators such as zinc white and stearic acid are examples of tongue agents, and vulcanization accelerators include, for example, sulfenamide-based accelerators, guanidine-based accelerators, and thiazole-based accelerators. Vulcanization accelerators, thiuram-based vulcanization accelerators, dithiate-based vulcanization accelerators and the like can be mentioned. Vulcanization acceleratorsThe amount of activator and vulcanization accelerator used is not particularly limited, as long as it is determined according to the use of the vulcanizate, required performance, type of sulfur vulcanizer, type of vulcanization accelerator, etc. Good.

When an organic peroxide is used, a vulcanization (crosslinking) auxiliary is usually used in combination. Examples of the vulcanization aid include triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, N, N'-m-phenylene bismaleimide and the like. These may be dispersed in clay, calcium carbonate, silica or the like to improve the workability of the rubber composition. The amount of the vulcanization aid used is not particularly limited, and may be determined according to the use of the vulcanizate, the required performance, the type of vulcanizing agent, the type of vulcanization aid, and the like.

In order to newly add a compounding agent or the like to the rubber composition of the present invention in addition to the compounding agent contained in the polymer composition, it is preferable to add the compounding agent after the heat treatment. At that time, the method of compounding the compounding agent into the general rubber composition may be followed, but it is necessary to perform the treatment at a temperature lower than the upper limit temperature of the heat treatment. To add a new compounding agent, etc., to a vulcanizable rubber composition obtained by compounding a vulcanizing agent, vulcanization aid, vulcanization accelerator, etc., it is necessary to mix the mixture so that the temperature is lower than the vulcanization start temperature. I just need.

The vulcanizate of the present invention may be obtained by curing the vulcanizable rubber composition at a temperature equal to or higher than the vulcanizing agent vulcanization start temperature. It is manufactured by heating the combined composition below the upper limit temperature of the heat treatment. The vulcanization temperature is not particularly limited, and in a general vulcanizing agent, preferably 100 to 200 ° C, more preferably 130 to 190 ° C, and particularly preferably 14 to 140 ° C. The temperature is 0 to 180 ° C, and the vulcanization temperature may be determined according to the characteristics (Tg, melting point, etc.) of the methyl methacrylate polymer. If the temperature is too low, vulcanization may take a long time or the vulcanization density may be low. Conversely, if the temperature is too high, molding may fail.

The vulcanization time varies depending on the vulcanization method, the vulcanization temperature, the shape of the target vulcanizate, etc., and is not particularly limited, but is preferably about 1 minute to 5 hours from the viewpoint of vulcanization density and production efficiency. . Depending on the shape and size of the target rubber vulcanizate, secondary vulcanization may be performed because the surface may be vulcanized but the inside may not be sufficiently vulcanized. . The vulcanization method may be appropriately selected from vulcanization methods commonly used in the production of vulcanized rubber products such as press vulcanization, steam (can) vulcanization, oven vulcanization, and hot air vulcanization.

Example

Hereinafter, the present invention will be described more specifically with reference to Reference Examples, Examples, and Comparative Examples. Parts and percentages are by weight unless otherwise specified. The measuring methods of various characteristics are as follows.

The Muney viscosity (ML _{1 + 4} , 100 ° C) was measured according to JISK630.

The molecular weight of the methyl methacrylate polymer was subjected to GPC using the tetrahydrofuran solution, and the weight average molecular weight in terms of standard polystyrene was measured. The particle size of the methyl methacrylate polymer was measured using a light scattering particle size analyzer (Model N4 manufactured by Coulter, Inc.). The glass transition temperature (T g) of the methyl methacrylate polymer was measured by a differential scanning calorimetry (DSC method). The methyl methacrylate polymers of Examples, Comparative Examples and Reference Examples were non-crystalline by X-ray diffraction, and the melting temperature could not be confirmed. Ozone resistance was determined at 40 ° C, 50 pphm, 30% elongation, 24 hours, 48 hours, 72 hours, and 168 hours after JISK 6259. Was evaluated. The evaluation results are shown by the following indicators.

NC: No crack is observed.

B — "! ~ C-1 5: The alphabet indicates the number of cracks. The number of cracks in C is larger than that in B. The larger the number, the longer the crack. Fracture: The crack became large and the test piece was cut.

Reference example 1

150 parts of ion-exchanged water, 0.1 part of sodium dodecylbenzenesulfonate (emulsifier), 0.3 part of ammonium persulfate (polymerization initiator), and 100 parts of methyl methacrylate were placed in a reaction vessel. While stirring, the reaction was carried out at a temperature of 80 ° C. for 12 hours to terminate the polymerization. As a result of sampling a part of the obtained polymerization reaction solution and measuring the solid content, the polymerization conversion was 98.3% and the solid content concentration was about 39%. The obtained particles of polymethyl methacrylate were in the form of particles having an average particle diameter of about 0.1 Aim. The weight average molecular weight of this polymethyl methacrylate was about 1,100,000.

The above polymerization reaction solution is filtered to collect polymethyl methacrylate particles, dispersed in pure water, filtered and washed twice, dried, and dried to obtain polymethyl methacrylate (PMM A-1 ) Were obtained. The glass transition temperature of the particles was measured to be 106 ° C.

Example 1

Nitrile group-containing copolymer rubber (HNBR-1) (Nippon Zeishin Co., Ltd. Hydrogenated nitrile-butadiene copolymer rubber: Z ET POL 1020, acrylonitrile unit content 44.2%, iodine value 24, mu) 100 parts of Keeney viscosity (ML _{1 +} 4,100 ° C) 78) 100 parts of particles of polymethyl methacrylate (PMMA-1) obtained in Reference Example 1 were roll-kneaded at 45 ° C, and polymer composition was obtained. Was taken out of the roll as a sheet.

Next, the roll temperature was adjusted to 170 ° C., the above-mentioned sheet-shaped polymer composition was wound, kneaded for 20 minutes, and heat-treated. The resulting rubber composition was taken out as a sheet and cooled until the sheet temperature became 40 ° C. or less. Thereafter, the roll was sufficiently cooled to 45 ° C., the sheet-shaped rubber composition was wound thereon, and each compounding agent was compounded according to the following compounding recipe and kneaded to obtain a vulcanizable rubber composition.

The vulcanizable rubber composition was pressed at 160 ° C. for 20 minutes to simultaneously perform molding and vulcanization to obtain a sheet-shaped vulcanized product having a thickness of 2 mm. The sheet-like vulcanizate was punched according to ISK 6301 to obtain a test piece, and the ozone resistance was evaluated. In addition, compression permanent strain was measured. Table 1 shows the results. Formulation

Rubber component 100 parts

Carbon black (Asahi # 50, manufactured by Asahi Carbon Co.) 60 parts

Plasticizer (adipate) Ί 5 parts

(Asahi Denka Co., Ltd)

1 part of stearic acid

Zinc flower # 1 5 parts

Sulfur (pass through 325 mesh) 0.5 parts

2-Mercaptobenzothiazole 0.5 part

Tetramethylthiuram disulphide 2 parts

Example 2

The HNBR-1 used in Example Ί was prepared into latex (average particle size of rubber particles: 0.1 m, latex solid content: 25%) by a known phase inversion method, and the solid content was referred to as Ί00 parts equivalent. The PMMA-1 obtained in Example 1 was mixed with 30 parts by weight of the solid content of the polymerization reaction solution in which the polymerization of PMMA-1 was stopped, and co-coagulated to collect the solid content and dried. Diethyl octyl phthalate (5 ^ 5) was blended with the obtained polymer composition, roll-kneaded at 45 ° C, and the polymer composition was taken out as a sheet, and subjected to heat treatment and heat treatment in the same manner as in Example 1. A vulcanized rubber composition was obtained, a vulcanized product was prepared, and the zoning resistance was evaluated. In addition, compression set was measured. Table 1 shows the results.

Example 3

A vulcanizate was produced in the same manner as in Example 1 except that the amount of PMMA-1 particles was changed to 60 parts, and its properties were evaluated. Table 1 shows the results.

Example 4

A vulcanizate was prepared in the same manner as in Example 1 except that the amount of PMMA-1 particles was changed to 80 parts, and its properties were evaluated. Table 1 shows the results.

Example 5

HNBR—2 instead of HNBR—Ί (Nippon Zeon Co., Ltd. Hydrogenated acrylonitrile-butadiene copolymer rubber: Z ET PO L 202 CK Acrylonitrile unit content 36.2%, iodine value 28, Moonee viscosity (ML _{1 A} vulcanizate was prepared in the same manner as in Example 1 except that ₊₄ , 100 ° C) 78) was used, and its properties were evaluated. Table 1 shows the results. Example 6

PMMA-2 particles instead of PMM A-1 particles (Acryl-St F320 manufactured by Zeishin Kasei Co., Ltd., average particle size 1 m, weight average molecular weight of PMMA about 3,000,000, glass A vulcanizate was prepared in the same manner as in Example 1 except that a transition temperature of 107 ° C) was used, and its characteristics were evaluated. Table 1 shows the results.

Comparative Example 1

A vulcanizate was prepared in the same manner as in Example 2 except that the amount of PMMA-1 particles used was changed to 5 parts, and its properties were evaluated. Table 2 shows the results.

Comparative Example 2

A rubber composition and a vulcanized product were produced in the same manner as in Example 1 except that the amount of PMA-1 particles used was changed to 170 parts. This composition was inferior in rubber elasticity, the vulcanized product was brittle, and it was difficult to produce a test piece for evaluating the zoning resistance. Comparative Example 3

A vulcanizate was produced in the same manner as in Example 1 except that the particles of PMM A-1 were not blended, and the characteristics were evaluated. Table 2 shows the results.

Comparative Example 4

A vulcanizate was produced in the same manner as in Example 1 except that the temperature of the heat treatment was changed to 100 ° C., and its characteristics were evaluated. Table 2 shows the results.

Comparative Example 5

HN BR-1 was converted to NBR (NIPO L 1041, manufactured by Zeon Corporation, acrylonitrile unit content: 40.5%, iodine value: 270, Mooney viscosity (ML _{1 + 4} , 100 ° C) 82. A vulcanized product was prepared in the same manner as in Example 1 except that the above was replaced with 5), and the characteristics were evaluated. Table 2 shows the results.

Comparative Example 6

A vulcanized product was prepared in the same manner as in Example 1 except that PMM A-1 was replaced with a vinyl chloride resin (PVC), and its properties were evaluated. Table 2 shows the results.

Comparative Example 7

PMMA-3 particles instead of PMM A-1 particles (Acryl Base F360, Zeon Kasei Co., Ltd., average particle size 35 m, weight average molecular weight of PMMA about 4,000,000, Except for using a glass transition temperature of 107 ° C.), a compounding agent was added to prepare a vulcanizable rubber composition in the same manner as in Example 1 to obtain a vulcanized product. Table 2 shows the results of evaluating the characteristics. Comparative Example 8

Instead of kneading HN BR-1 and PMM A-1 in advance and then heat-treating them with a roll at 170 ° C, they knead them thoroughly with a roll at 170 ° C from the beginning to form a polymer composition. Except for the preparation, a compounding agent was added in the same manner as in Example 1 to prepare a vulcanizable rubber composition, and its characteristics were evaluated. Table 2 shows the results.

table 1

(Note) (*): Latex blend

Table 2

The results shown in Tables 1 and 2 show the following.

When the amount of the methyl methacrylate polymer particles is too small, the ozone resistance is poor (Comparative Example 1), and when too much, the compression set is poor (Comparative Example 2). Without the addition of the methyl methacrylate polymer particles, the ozone resistance is poor (Comparative Example 3). If the heat treatment temperature is too low, the ozone resistance is poor (Comparative Example 4). Using a nitrile group-containing rubber having a high iodine value results in poor ozone resistance (Comparative Example 5). When vinyl chloride resin (PVC) is used in place of the methyl methacrylate polymer particles, the compression set is inferior (Comparative Example 6). When methyl methacrylate polymer particles having a large particle diameter are used, the ozone resistance is poor (Comparative Example 7). When the mixing of the nitrile group-containing rubber and the methyl methacrylate polymer particles and the heat treatment are performed simultaneously, the ozone resistance is poor (Comparative Example 8).

In contrast, all of the products of the present invention (Examples) have excellent ozone resistance and low compression set. Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in ozone resistance and has a small compression set with a nitrile group containing. A rubber vulcanizate is provided.

This rubber vulcanizate is used for industrial parts such as rolls, hoses, belts, and sealing materials, as well as automotive rubber such as packing, fuel hoses, air intake hoses, air duct hoses, boot materials, and oil seal automotive interior parts. It is suitable as a part.

Claims

The scope of the claims

1. A copolymer having an iodine value of 100 or less and containing a ditolyl group-containing copolymer (A) of 100 and overlapping portions, and a methyl methacrylate homopolymer or methyl methacrylate having an average particle diameter of 10 β m or less. Copolymer particles containing unit 50% by weight or more (B) 10-1 A polymer composition containing 50 parts by weight.

2. The copolymer rubber containing a nitrile group (A) is composed of 10-60% by weight of) 8-ethylenically unsaturated ditolyl monomer unit, and a conjugated diene monomer or a non-conjugated diene monomer. , Α-olefin monomer, aromatic vinyl monomer, fluorine-containing vinyl monomer, α, —ethylenically unsaturated monocarboxylic acid monomer, —ethylenically unsaturated polycarboxylic acid or Hydrate, α,) 8-ethylenically unsaturated carboxylic acid ester monomer, and monomer units selected from copolymerizable antioxidants, and hydrogenated units of these monomers. 2. The polymer composition according to claim 1, which is a copolymer containing at least one unit selected from the group consisting of 40 to 90% by weight.

3. The copolymer containing two toryl groups (Α) is composed of 10 to 60% by weight of acrylonitrile unit and at least one unit selected from 1,3-butanediene unit and its hydrogenated unit. 2. The polymer composition according to claim 1, which is a copolymer containing 90% by weight.

4. The copolymer containing nitrile group (Α) is composed of 12 to 55% by weight of acrylonitrile unit and at least one unit selected from 1,3-butadiene unit and its hydrogenated unit. 2. The polymer composition according to claim 1, which is a copolymer containing 1% by weight.

5. The polymer composition according to any one of claims 1 to 4, wherein the iodine value of the nitrile group-containing copolymer rubber (ii) is 80 or less.

6. The polymer composition according to any one of claims 1 to 5, wherein the halogen content in the nitrile group-containing copolymer rubber (ii) is 0 to 0.5% by weight.

7. The rubber according to any one of claims 1 to 6, wherein the copolymer (含有) having a nitrile group has a viscosity of ML _{1 + 4} (100 ° C) in the range of Ί0-300. Polymer composition.

8. The polymer constituting the particles (粒子) may be a homopolymer of methyl methacrylate or 50% by weight or more of methyl methacrylate units and a monomer of at least one copolymerizable monomer. 8. The polymer composition according to any one of claims 1 to 7, which is a copolymer comprising at most 50% by weight.

9. Copolymerizable monomers include methacrylate monomer other than methyl methacrylate, acrylate monomer, aromatic vinyl monomer, ethylenically unsaturated ditolyl monomer, vinyl ester 9. The polymer composition according to claim 8, which is at least one selected from a monomer and a vinyl ether monomer.

10. The polymer composition according to any one of claims 1 to 9, wherein the polymer constituting the particles (B) has a glass transition temperature of 80 ° C or higher.

1 1. The polymer composition according to any one of claims 1 to 10, wherein the halogen content of the polymer constituting the particles (B) is 0 to 0.5% by weight.

1 2. The polymer composition according to any one of claims 1 to 11, wherein the crosslinkable functional group content per 100 g of the polymer constituting the particles (B) is 0 to 0.01 equivalent. .

1 3. The weight average molecular weight of the polymer constituting the particles (B) (polystyrene conversion value measured by gel permeation-chromatography) is in the range of 50,000 to 400,000, 000,000. 13. The polymer composition according to any one of to 12.

14. The polymer composition according to any one of claims 1 to 13, wherein the average particle size of the particles (B) is in the range of 0.01 to 5 m.

1 5. The method according to any one of claims 1 to 14, wherein the amount of the particles (B) is in the range of 15 to 100 parts by weight based on 100 parts by weight of the copolymer rubber containing nitrile group (A). 6. The polymer composition according to item 1.

1 6. Heat treatment of the polymer composition according to any one of claims 1 to 15 at a temperature at least 20 ° C higher than the glass transition temperature (T g) of the polymer constituting the particles (B). A rubber composition obtained by this.

1 7. The polymer that makes up the particles (B) is an amorphous polymer that has a temperature in the range of at least 20 ° C above its glass transition temperature (Tg) to 300 ° C. The rubber composition according to claim 16, which is obtained by heating.

1 8. The polymer constituting the particles (B) is a crystalline polymer, and is subjected to a heat treatment in a range from a temperature at least 20 ° C higher than its glass transition temperature (Tg) to a melting temperature. The rubber composition according to claim 16 obtained.

19. A vulcanizable rubber composition obtained by blending a vulcanizing agent with the polymer composition according to any one of claims 1 to 15.

20. A vulcanizable rubber composition obtained by mixing a vulcanizing agent with the rubber composition according to any one of claims 16 to 18.

21. A vulcanizing agent selected from a sulfur-based vulcanizing agent and an organic peroxide is added in an amount of 0.1 to 10 weight per 100 parts by weight of the copolymer rubber containing nitrile group (A). 21. The vulcanizable rubber composition according to claim 19 or 20, including a mounting portion.

22. A rubber vulcanizate obtained by vulcanizing the vulcanizable rubber composition according to claim 21.