JP2014098132A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which does not deteriorate workability even if a large amount of an inorganic filler is blended into a rubber component including a butyl rubber and to provide a rubber component which has less cracks from an end part of a roll sheet during taking off the roll due to excellent tear strength and is improved in roll processability.SOLUTION: There is provided a rubber composition which comprises: a rubber component (A) including a butyl rubber; an inorganic filler (B); and a PTFE and/or PTFE-containing organic polymer (C), wherein 0.5 to 10 pts.mass of the PTFE and/or PTFE-containing organic polymer (C) is contained based on 100 pts.mass of the rubber component (A) including a butyl rubber and the inorganic filler (B).

Description

  The present invention relates to a rubber composition containing PTFE and / or a PTFE-containing organic polymer in a rubber component containing butyl rubber and an inorganic filler.

  Butyl rubber has excellent gas barrier properties because of its low gas permeability, and is widely applied to sealing parts such as tubes and gaskets, industrial rolls, and the like. However, butyl rubber is usually a copolymer of isobutene and isoprene and has problems in mechanical strength, heat aging resistance and processability.

  In addition, a rubber component containing butyl rubber often contains a large amount of an inorganic filler for the purpose of imparting chemical resistance, hardness and wear resistance. Therefore, when a large amount of the inorganic filler is included, the processability is remarkably inferior, so that there is a problem that the yield is deteriorated. In particular, there is a problem that cracks are generated from the end of the roll sheet during roll processing, and the roll sheet is difficult to process.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a rubber composition that does not deteriorate processability even when a large amount of an inorganic filler is blended with a rubber component containing butyl rubber. In particular, since the tear strength is excellent, a rubber composition having an improved roll processability is provided by reducing cracks from the end of the roll sheet during roll take-up.

  The present invention relates to a rubber composition containing a rubber component (A) containing butyl rubber, an inorganic filler (B), and a PTFE and / or PTFE-containing organic polymer (C), the PTFE and / or PTFE-containing organic heavy The coalescence (C) relates to a rubber composition containing 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A) containing butyl rubber and the inorganic filler (B).

  Further, the rubber composition of the present invention can be used after being vulcanized.

  In the present invention, the rubber composition is particularly excellent in workability at the time of roll processing, and can be blended in a large amount with an inorganic filler without reducing productivity, so it is suitable for various industrial rolls, tubes, gaskets and the like. It is.

Hereinafter, the present invention will be described in detail.
The rubber composition of the present invention is a rubber composition containing a rubber component (A) containing butyl rubber, an inorganic filler (B), and PTFE and / or a PTFE-containing organic polymer (C), wherein PTFE and / or The PTFE-containing organic polymer (C) is contained in an amount of 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A) containing butyl rubber and the inorganic filler (B).
By containing PTFE, PTFE is dispersed in a fibrous form in the rubber component, and by forming a network, elasticity and tension can be added to the rubber composition, so that processability is improved.

  The rubber component used in the present invention is composed of butyl rubber (IIR) or butyl rubber (IIR) and other rubber components. Butyl rubber (IIR) is a copolymer of isobutene and isoprene. Other rubber components include natural rubber (NR), polyisoprene rubber (IR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), Chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylic rubber (ACM), chlorosulfonated polyethylene (CSM), urethane rubber, silicone rubber, fluoro rubber ( FKM), epichlorohydrin rubber (ECO), hydrogenated nitrile rubber (H-NBR), and the like. These may be used alone or in combination of two or more.

  Examples of the inorganic filler used in the present invention include fibrous or non-fibrous inorganic fillers, and specific examples thereof include glass fiber, carbon fiber, potassium titanate whisker, zinc oxide whisker, aluminum borate whisker, Fibrous fillers such as aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, stone-cow fiber, metal fiber, wollastonite, zeolite, sericite, kaolin, mica, clay, pyrophyllite, bentonite, montmorillonite Silicates such as asbestos, talc and aluminosilicates, metal oxides such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide and iron oxide, carbonates such as calcium carbonate, magnesium carbonate and dolomite, calcium sulfate, Sulfuric acid such as barium sulfate , Magnesium hydroxide, calcium hydroxide, hydroxides such as aluminum hydroxide, glass beads, ceramic beads, boron nitride, non-fibrous fillers such as silicon carbide and silica. These may have a hollow shape, and two or more of these inorganic fillers can be used in combination. In addition, it is better to use these fillers after pretreatment with coupling agents such as isocyanate compounds, acrylic compounds, organic silane compounds, organic titanate compounds, organic borane compounds, epoxy compounds, etc. This is preferable in terms of obtaining the desired strength.

  PTFE is obtained by polymerizing a monomer containing tetrafluoroethylene as a main component by a known method, and impairs the characteristics of tetrafluoroethylene homopolymer or polytetrafluoroethylene (PTFE). As long as there are no copolymerization components, copolymerization with fluorine-containing olefins such as hexafluoropropylene, fluoroalkylethylene and perfluoroalkyl vinyl ether, and fluorine-containing alkyl (meth) acrylates such as perfluoroalkyl (meth) acrylate, is possible. A polymer is mentioned.

  The PTFE-containing organic polymer is composed of 10 to 90% by mass of PTFE and 90 to 10% by mass of a polymer obtained by polymerizing a vinyl monomer or an organic polymer obtained by polycondensation.

  Examples of vinyl monomers include aromatic vinyl compounds, vinyl cyanide compounds, (meth) acrylic acid esters, and other copolymerizable monomers.

  Examples of the aromatic vinyl compound include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N, N-diethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, vinylpyridine, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, fluorostyrene, ethylstyrene, vinylnaphthalene and the like can be mentioned. These are used alone or in combination of two or more. As the aromatic vinyl compound, styrene and α-methylstyrene are particularly preferable.

  Examples of the cyanated vinyl compound include acrylonitrile and methacrylonitrile. These are used alone or in combination of two or more. As the vinyl cyanide compound, acrylonitrile is particularly preferable.

  Examples of (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, octadecyl acrylate, phenyl acrylate, and benzyl. Acrylic esters such as acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate Phenyl methacrylate, and methacrylic acid esters such as benzyl methacrylate. These are used alone or in combination of two or more. As the (meth) acrylic acid ester, methyl methacrylate, butyl methacrylate, and isobutyl methacrylate are particularly preferable.

  Examples of other copolymerizable monomers include unsaturated acid anhydrides such as maleic anhydride, itaconic anhydride and citraconic anhydride; unsaturated acids such as acrylic acid and methacrylic acid; maleimide and N-methylmaleimide , N-butylmaleimide, N- (p-methylphenyl) maleimide, N-phenylmaleimide, N-cyclohexylmaleimide and other maleimide compounds; glycidyl methacrylate and other epoxy compounds. The maleimide compound includes, for example, a copolymer obtained by copolymerizing maleic anhydride and imidizing it with aniline or the like. The above vinyl monomers can be used singly or in combination of two or more.

  The PTFE-containing organic polymer is obtained by a method of polymerizing a vinyl monomer constituting the organic polymer in the presence of PTFE, or a method of mixing a latex of PTFE and a latex of an organic polymer. The method for polymerizing the vinyl monomer in the presence of PTFE is preferably emulsion polymerization.

Specifically, the emulsion polymerization of a vinyl monomer is usually heated to 5 to 98 ° C. while stirring a vinyl monomer added with a polymerization initiator, a chain transfer agent, an emulsifier and the like. Done.
As a polymerization initiator, redox by combining organic hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide and reducing agents such as sugar-containing pyrophosphate prescription and sulfoxylate prescription. System polymerization initiators or peroxides such as persulfate, azobisisobutyronitrile, benzoyl peroxide are used.

  Chain transfer agents include mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-stearyl mercaptan; chloroform, bromoform, carbon tetrachloride, tetraodor Hydrocarbons such as carbonized carbon; xanthogens such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; α-methylstyrene dimer, 9,10-dihydroanthracene, 1,4-cyclohexadiene, 1,4-hexadiene, 2, 5-dihydrofuran etc. are mentioned.

As the emulsifier, commonly used emulsifiers can be used, sodium salts or potassium salts of fatty acids such as rosin acid, oleic acid, lauric acid, stearic acid, alkenyl succinic acid, alkylallyl sulfonates such as sodium dodecylbenzene sulfonate, Anionic surfactants such as dialkylsulfosuccinic acid are preferred.
As the emulsion polymerization method, generally known emulsion polymerization methods such as batch addition polymerization of monomers, continuous addition polymerization of monomers, and multistage polymerization can be employed. Can be added.

  The PTFE or PTFE-containing organic polymer can also be used in a latex state. For example, the polymer can be recovered as a solid by a method such as a coagulation method, a spray drying method, a centrifugal separation method, or a freeze drying method. Among these recovery methods, the coagulation method and the spray drying method are preferable from the viewpoint of the uniformity of the obtained powder.

  When powder recovery of PTFE or PTFE-containing organic polymer is carried out using the coagulation method, the latex of PTFE or PTFE-containing organic polymer is brought into contact with the coagulant at 30 to 90 ° C. and coagulated with stirring. PTFE or PTFE-containing organic polymer powder can be recovered by slurrying and drying. Examples of the coagulant used in the coagulation method include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; organic acids such as formic acid and acetic acid; inorganic salts such as aluminum sulfate, magnesium sulfate and calcium sulfate; organics such as calcium acetate Examples include salts.

  When powder recovery of PTFE or PTFE-containing organic polymer is performed using the spray drying method, the latex of PTFE or PTFE-containing organic polymer is sprayed under conditions of an inlet temperature of 120 to 220 ° C and an outlet temperature of 40 to 90 ° C. By spray-drying with a drier, PTFE or PTFE-containing organic polymer powder can be recovered.

  The addition amount of PTFE and / or PTFE-containing organic polymer is 0.5 to 10 parts by mass, preferably 0.5 to 5 parts by mass. If the amount added is less than 0.5 part, the processability improvement effect of the rubber composition cannot be obtained, and if it exceeds 10 parts by weight, the deterioration of the appearance due to poor dispersion and the processability decrease due to the elasticity imparting effect being too strong are considered It is done.

  The rubber composition of the present invention can be used after being vulcanized. As the vulcanizing agent, all conventionally known sulfur compounds that are usually used are used. Specifically, there are powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur, which can be blended with a sulfur masterbatch compound in which these are dispersed in advance in a polymer or an inorganic filler.

  The sulfur compound is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the rubber composition.

  Moreover, it is preferable to mix | blend a vulcanization accelerator as needed. In its use, there are no particular restrictions on the type and method of use of the vulcanization accelerator, and all known types and methods can be applied.

  Specific examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N, N-diisopropyl-2-benzothiazole sulfenamide. , 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazole, dibenzothiazyl disulfide, and the like; diphenylguanidine , Guanidine compounds such as triphenylguanidine, diorthotolylguanidine, orthotolylbiguanide, diphenylguanidine phthalate; acetaldehyde-aniline reaction product, butyraldehyde-aniline reaction product, hexamethylenetetramine Aldehyde-amine or aldehyde-ammonia compounds such as acetaldehyde-ammonia reactant; imidazoline compounds such as 2-mercaptoimidazoline; thiourea compounds such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea; tetramethyl Thiuram compounds such as thiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc di-n-butyldithiocarbamate, ethylphenyl Zinc dithiocarbamate, zinc butylphenyl dithiocarbamate, dimethyldithioca Xanthates such as dibutyl xanthate zinc; sodium vammin acid, dimethyl dithiocarbamate selenium dithiocarbamate tellurium diethyldithiocarbamate and the like other compounds, such as zinc white (zinc oxide) and the like.

  A vulcanization accelerator can be used individually by 1 type or in combination of 2 or more types. The amount is preferably 0 to 20 parts by weight with respect to 100 parts by weight of the rubber composition.

  Moreover, a well-known organic peroxide can also be used as a vulcanizing agent without a restriction | limiting. The compounding amount of the organic oxide is 0.005 to 3.0 parts by mass with respect to 100 parts by mass of the rubber composition.

  Specific examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, di-t- Amyl peroxide, t-butyl hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5 -Dialkyl peroxides such as dimethyl-2,5-mono (t-butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene; t-butylperoxyacetate, t-butylperoxyiso Butyrate, t-butylperoxybivalate, t-butylperoxymaleic acid, t-butylpe Peroxyesters such as ruoxyneodecanoate, t-butylperoxybenzoate, di-t-butylperoxyphthalate, 1,1-bis-t-butylperoxy-3,3,5-tri-methylcyclohexane; dicyclohexanone Ketone peroxides such as peroxides; and mixtures thereof.

  The rubber composition of the present invention is performed by kneading by a general method using a kneader such as a kneader or a Banbury mixer or a mixer and a roll.

  The rubber composition of the present invention is suitably used for sealing parts such as tubes and gaskets, industrial rolls, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In the examples, “parts” and “%” indicate “parts by mass” and “% by mass”.

(Sheet appearance)
15 parts by mass of butyl rubber and 35 parts by mass of EPDM and 25 parts by mass of calcium carbonate and 25 parts by mass of talc as inorganic fillers were mixed with a Banbury mixer, and a temperature of 130 ° C. was used using an 8 inch dielectric heating roll (roll interval: 1 mm). Roll kneading was performed under conditions, and the state of the end of the roll sheet was visually observed. Those with good moldability do not crack at the edges. Those with poor moldability will crack from the edges. The case where no crack occurred was evaluated as ◯, and the case where a crack occurred was evaluated as x.

(Tear strength)
The roll sheet obtained by the sheet appearance evaluation was sampled by punching a JIS K6252 non-cut angle test piece. The tear strength was measured in accordance with JIS K6252 under the condition that the moving speed of the test piece knob was 500 mm / min.

[Reference Example 1]
<Production of PTFE-containing organic polymer>
As an emulsifier, alkenyl succinate dipotassium (manufactured by Kao Corporation, “Latemul ASK”, active ingredient 28%) 0.50 part (as an active ingredient), distilled water 145 parts (including the water content of the emulsifier aqueous solution), methyl methacrylate 40 parts Then, 10 parts of butyl acrylate was charged into a 5 L separable flask equipped with a stirring blade, a condenser, a thermocouple, and a nitrogen inlet, and heated to 60 ° C. under a nitrogen stream. Subsequently, what melt | dissolved 0.1 part of potassium persulfate in 5 parts of distilled water was added, and radical polymerization was started. After completion of the polymerization heat generation, the jacket temperature was held at 60 ° C. for 1 hour to obtain a vinyl polymer latex.
To this latex, polytetrafluoroethylene (hereinafter abbreviated as “PTFE”) particle dispersion, “Fluon AD939” 83.3 parts (50 parts as PTFE content) manufactured by Asahi Glass Co., Ltd., and 16.7 parts of distilled water are added. Latex was obtained.

Next, after adding 500 parts of 1% calcium acetate aqueous solution to a 20 L coagulation vessel, heating and stirring at 80 ° C., gradually dropping 300 parts of polymer latex (100 parts as a polymer) while maintaining the temperature, After solidifying and precipitating to make a slurry, stirring was continued for 5 minutes. Then, the temperature of the slurry was raised to 95 ° C. and solidified. Finally, this precipitate was separated, filtered, washed with water, and dried to obtain a PTFE-containing organic polymer (A).
As PTFE powder, Asahi Glass Co., Ltd. full-on CD-1 was used.

[Example 1]
15 parts by mass of butyl rubber and 35 parts by mass of EPDM and 25 parts by mass of calcium carbonate as an inorganic filler, 25 parts by mass of talc, and 0.5 parts by mass of PTFE powder “Fluon CD-1” (manufactured by Asahi Glass Co., Ltd.) were mixed in a Banbury mixer. Using an 8-inch dielectric heating roll (roll interval: 1 mm), roll kneading was performed at a temperature of 130 ° C., and appearance observation and roll sheet preparation were performed.

[Examples 2 and 3]
The same operation as in Example 1 was performed except that the amount of PTFE powder added in Example 1 was changed as shown in Table 1.

[Examples 4 and 5]
The same operation as in Example 1 was performed except that the PTFE powder of Example 1 was changed to a PTFE-containing organic polymer and the addition amount was changed as shown in Table 1.

[Comparative example]
Roll sheet molding and appearance evaluation were performed without adding the PTFE powder and PTFE-containing organic polymer described in the Examples.

  The results are shown in Table 1.

  As clearly shown in Table 1, it can be said that the rubber composition of the present invention to which PTFE and / or PTFE-containing organic polymer is added is excellent in appearance and improved in tearing strength, and thus has good molding processability.

  According to the rubber composition of the present invention, even if a large amount of an inorganic filler is blended in a sealing part such as a tube or a gasket or an industrial roll, it can be produced without degrading processability, so that the utility value is extremely high.

Claims (2)

A rubber composition containing a rubber component (A) containing butyl rubber, an inorganic filler (B), and PTFE and / or a PTFE-containing organic polymer (C),
A rubber composition containing PTFE and / or PTFE-containing organic polymer (C) in an amount of 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A) and inorganic filler (B) containing butyl rubber.
  2. A rubber composition obtained by vulcanizing the rubber composition according to claim 1.