JP2012184408A - Modified diene rubber, method for production thereof, and rubber composition using the rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified diene rubber with low energy loss and excellent rebound resilience, and to provide a method for production thereof, and a rubber composition using the rubber.SOLUTION: The modified diene rubber is obtained by reacting an epoxidized diene rubber having an epoxidation rate of ≥0.1% to <15%, alkoxysilane having the functional group to be reacted with an epoxy group, and carboxylic acid. The method for production of the modified diene rubber is characterized by mechanically kneading and reacting the epoxidized diene rubber having the epoxidation rate of ≥0.1% to <15%, alkoxysilane having the functional group to be reacted with an epoxy group, and carboxylic acid.

Description

  The present invention relates to a modified diene rubber, a method for producing the same, and a rubber composition using the same.

  In recent years, awareness of environmental issues has increased, and rubber materials for fuel-efficient tires have been actively developed for the purpose of improving the fuel efficiency of automobiles. Such rubber materials for tires intended for low fuel consumption are desired to be excellent in mechanical properties, low energy loss, etc., and to achieve this, the dispersibility of silica as a filler is improved. A technique for reducing heat generation by reducing friction between rubber molecules and friction between silica and rubber molecules is known. And in order to improve the dispersibility of a silica, many techniques which epoxidize-modify the rubber | gum used as the material are developed (patent document 1).

Japanese Patent No. 3363539

  However, the tire tread rubber composition described in Patent Document 1 does not necessarily have sufficient mechanical properties, low energy loss, and the like. Accordingly, an object of the present invention is to provide a modified diene rubber particularly excellent in low energy loss and impact resilience, a method for producing the same, and a rubber composition using the same.

  As a result of intensive studies to achieve the above object, the present inventors have added a large number of alkoxysilanes by reacting an epoxidized diene rubber with a limited epoxidation rate with alkoxysilanes and carboxylic acids. A modified diene rubber can be produced, and a rubber composition using the rubber has been found to be particularly excellent in low energy loss and rebound resilience, leading to the present invention. That is, the present invention relates to a modified diene rubber obtained by reacting an epoxidized diene rubber having an epoxidation rate of 0.1% or more and less than 15%, an alkoxysilane having a functional group that reacts with an epoxy group, and a carboxylic acid.

  In the present invention, an epoxidized diene rubber having an epoxidation rate of 0.1% or more and less than 15% is reacted with an alkoxysilane having a functional group that reacts with an epoxy group and a carboxylic acid by mechanical kneading. The present invention relates to a method for producing a modified diene rubber.

  Furthermore, the present invention relates to a modified diene rubber composition comprising the modified diene rubber and silica.

  As described above, according to the present invention, it is possible to provide a modified diene rubber particularly excellent in low energy loss and impact resilience, a method for producing the same, and a rubber composition using the same.

  In the modified diene rubber according to the present invention, the diene rubber used as a raw material is not particularly limited, and a known rubber can be used. For example, natural rubber, butadiene rubber (BR), syndiotactic-1,2-polybutadiene-containing butadiene rubber (VCR), isoprene rubber, butyl rubber, chloroprene rubber and the like. Among these, butadiene rubber is particularly preferable. The diene rubber may be used alone or in combination of two or more. However, in the combination of two or more, one type of single weight may be used because the modification may be biased to only one of them. Coalescence is preferred.

  The diene rubber preferably has a weight average molecular weight (Mw) by GPC (gel permeation chromatography) of 50,000 to 2,000,000, further 200,000 to 1,000,000, particularly 400,000 to 800,000. When the weight average molecular weight (Mw) is less than 50,000, the mechanical strength is lowered, and when it exceeds 2 million, the workability is deteriorated.

  The diene rubber is epoxidized at an epoxidation rate of 0.1% or more and less than 15%, more preferably 0.2% to 5%, particularly preferably 0.5% to 2.5%. It is.

  The method for epoxidizing the diene rubber is not particularly limited, and examples thereof include a method using monoperphthalic acid (Japanese Patent Laid-Open No. 51-060292), hydrogen peroxide together with organic peracid or carboxylic acid anhydride. Known methods described in, for example, a method using water (Japanese Patent Laid-Open No. 05-214141), a method using a tungstic acid catalyst and a phosphoric acid compound, a phase transfer catalyst and hydrogen peroxide (Japanese Patent No. 3944927) are used. It is done.

  In addition, examples of the method for adjusting the epoxidation rate during the epoxidation include ordinary methods such as adjusting the amount of hydrogen peroxide added, adjusting the reaction temperature, and adjusting the reaction time. . An epoxidation rate of less than 0.1% is not preferable in that the number of epoxy groups that react with an alkoxysilane having a functional group that reacts with an epoxy group is insufficient. In addition, when the epoxidation rate is 15% or more, it is preferable from the viewpoint that unsaturated bonds are reduced and rubber elasticity is lowered, and that when sulfur vulcanization is used, reversion is likely to occur and mechanical properties are lowered. Absent.

  In the modified diene rubber according to the present invention, the alkoxysilane having a functional group that reacts with an epoxy group is not particularly limited as long as it can undergo an addition reaction with the epoxy group in the epoxidized diene rubber.

  Examples of the functional group that reacts with the epoxy group include amino group, mercapto group, vinyl group, ureido group, acryloxy group, isocyanate group, styryl group, methacryloxy group, sulfide group, nitro group, halogen group, epoxy group or glycidyl. A group having a thiocarbamoyl tetrasulfide structure, a benzothiazole tetrasulfide structure, or a methacrylate monosulfide structure.

  Examples of the alkoxysilane having a functional group that reacts with an epoxy group include 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3- Aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethylbutoxysilane, 3-aminopropylmethyldibutoxysilane, 3- (2-aminoethylaminopropyl) Dimethoxymethylsilane, 3- (2-aminoethylaminopropyl) dimethoxyethylsilane, 3- (2-aminoethylaminopropyl) dimethoxypropylsilane, 3- (2-aminoethylaminopropyl) di Toxibutylsilane, 3- (2-aminoethylaminopropyl) diethoxymethylsilane, 3- (2-aminoethylaminopropyl) trimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane, 3- ( Those having an amino group, such as 2-aminoethylaminopropyl) tributoxysilane. Among these compounds, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethylaminopropyl) dimethoxymethylsilane, 3- (2-amino) are particularly preferred from the viewpoint of modification effects. Ethylaminopropyl) trimethoxysilane is preferably used.

  Furthermore, as an alkoxysilane having a functional group that reacts with an epoxy group, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, etc. Those having a mercapto group, those having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane, those having a ureido group such as 3-ureidopropyltriethoxysilane, and acryloxy groups such as 3-acryloxypropyltrimethoxysilane Those having an isocyanate group such as 3-isocyanatopropyl and triethoxysilane, those having a styryl group such as p-styryltrimethoxysilane, and 3-methacryloxypropylmethyldi Those having a methacryloxy group such as toxisilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, bis (3-triethoxysilylpropyl) tetrasulfide, bis Those having a sulfide group such as (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-nitropropyltrimethoxysilane, Those having a nitro group such as 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloro One having a halogen group such as tilt triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxy Those having a thiocarbamoyl tetrasulfide structure such as silylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, benzothiazole tetrasulfides such as 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide Methacrylates such as those having a structure, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, diethoxy (3-glycidyloxypropyl) The thing etc. which have epoxy groups or glycidyl groups, such as methylsilane and 3-glycidyloxypropyl (dimethoxy) methylsilane, are mentioned. Among these compounds, alkoxysilanes having a glycidyl group or an epoxy group such as 3-glycidyloxypropyltrimethoxysilane are preferably used because the performance after reaction is particularly excellent.

  Furthermore, examples of the alkoxysilane having a functional group that reacts with an epoxy group include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, ethyltrimethoxysilane, diethyldimethoxysilane, triethylmethoxysilane, and tetraethoxy. Silane, methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, ethyltriethoxysilane, diethyldiethoxysilane, triethylethoxysilane, tetrabutoxysilane, methyltributoxysilane, dimethyldibutoxysilane, trimethylbutoxysilane, ethyltri Butoxysilane, diethyldibutoxysilane, triethylbutoxysilane, trimethoxysilane, methyldimethoxysilane, dimethylmethan Xysilane, ethyldimethoxysilane, diethylmethoxysilane, triethoxysilane, methyldiethoxysilane, dimethylethoxysilane, ethyldiethoxysilane, diethylethoxysilane, tributoxysilane, methyldibutoxysilane, dimethylbutoxysilane, ethyldibutoxysilane, Diethylbutoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, tetrapropoxysilane, methyltripropoxysilane, dimethyldipropoxysilane, ethyltripropoxy Examples include silane and diethyldipropoxysilane. Among these compounds, tetramethoxysilane and tetraethoxysilane are preferably used particularly from the viewpoint of both the effect of addition and cost. The alkoxysilane having a functional group that reacts with the epoxy group may be used alone or in combination of two or more.

  The amount of alkoxysilane having a functional group that reacts with these epoxy groups is preferably 0.001 mol to 0.3 mol, more preferably 0.002 mol to 0.25 mol, particularly preferably 100 g per 100 g of epoxidized diene rubber. Is 0.003 mol to 0.1 mol. When the amount of alkoxysilane used is less than 0.001 mol, the amount of alkoxysilane introduced into the epoxidized diene rubber is reduced, and a satisfactory modification effect does not appear. On the other hand, if the amount of alkoxysilane used exceeds 0.3 mol, unreacted alkoxysilane remains in the epoxidized diene rubber, and it takes time to remove it, resulting in waste of alkoxysilane and further remarkable physical properties. The improvement effect is difficult to appear.

  In the modified diene rubber according to the present invention, the carboxylic acid to be reacted with the epoxy group together with the alkoxysilane is not particularly limited, and is saturated monocarboxylic acid, saturated dicarboxylic acid, aromatic monocarboxylic acid, aromatic dicarboxylic acid, unsaturated Examples thereof include monocarboxylic acids, unsaturated dicarboxylic acids, and unsaturated and saturated carboxylic acids having three or more carboxyl groups. Examples of saturated monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristylic acid, palmitic acid, margaric acid, stearic acid Etc. Examples of the saturated dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like. Examples of the aromatic monocarboxylic acid include benzoic acid, m-toluic acid, o-toluic acid, p-toluic acid, cinnamic acid, and mellitic acid. Examples of the aromatic dicarboxylic acid include isophthalic acid, terephthalic acid, and phthalic acid. Examples of unsaturated monocarboxylic acids include α-eleostearic acid, α-linolenic acid, γ-linolenic acid, arachidonic acid, arachidonic acid, sardine acid, eicosadienoic acid, eicosatetraenoic acid, eicosatrienoic acid, Eicosapentaenoic acid, eicosenoic acid, elaidic acid, erucic acid, ozbond acid, oleic acid, gadoleic acid, crotonic acid, dihomo-γ-linolenic acid, tetracosapentaenoic acid, docosahexaenoic acid, nisic acid, nervonic acid, vaccenic acid Examples include palmitoleic acid, boseopentaenoic acid, mead acid, myristoleic acid, and linoleic acid. Examples of the unsaturated dicarboxylic acid include fumaric acid and maleic acid. Among these compounds, saturated monocarboxylic acids or saturated dicarboxylic acids are used because they are chemically stable except for the carboxyl group, have a high boiling point and are difficult to volatilize, and have a high effect when a silane modifier is added. Saturated dicarboxylic acids are preferred and particularly preferred. Specifically, stearic acid and malonic acid are more preferable, and malonic acid is particularly preferable. You may use the said carboxylic acid individually by 1 type or in combination of 2 or more types.

  The amount of these carboxylic acids used is preferably 10 μmol / g or more and 5000 μmol / g or less, more preferably 50 μmol / g or more and 1000 μmol / g or less, particularly preferably 80 μmol / g or more, relative to the epoxidized diene rubber. 500 μmol / g or less. When the amount of carboxylic acid used is less than 10 μmol / g, the silane modifier is not sufficiently added. On the other hand, if the amount of carboxylic acid used exceeds 5000 μmol / g with respect to the epoxidized diene rubber, the reaction between the modified group added to the epoxidized diene rubber and the inorganic filler is hindered when the rubber composition is formed. It is not preferable.

  The modified diene rubber according to the present invention is obtained by mechanically treating an epoxidized diene rubber having an epoxidation rate of 0.1% or more and less than 15% with an alkoxysilane having a functional group that reacts with an epoxy group in the presence of a carboxylic acid. The reaction is characterized by kneading. By mechanically kneading, a modified diene rubber can be produced at low cost with good production efficiency and without generating waste liquid or the like. In the present invention, for example, the reaction may be carried out by kneading alkoxysilane and carboxylic acid into a raw material epoxidized diene rubber using a preheated kneader, or used as an epoxidation catalyst during production. The neutralization step in which carboxylic acid is usually performed may be omitted and used as it is.

  As reaction temperature of the said reaction, 20 to 140 degreeC is preferable, More preferably, it is 40 to 120 degreeC. If it is less than 20 ° C., the reaction of the functional group of the epoxy group and alkoxysilane does not occur, and if it exceeds 140 ° C., thermal degradation of the diene rubber occurs.

  In the method for producing a modified diene rubber according to the present invention, mechanical kneading means kneading a molten resin by applying mechanical shearing force, and the kneader used for kneading gives mechanical shearing force. There is no particular limitation as long as it is an apparatus capable of kneading a molten resin, and a roll kneader, a Banbury mixer, a pressure kneader, a single screw extruder, a twin screw extruder, a twin screw taper extruder, etc., which are commonly used for resin processing A kneading machine can be used.

  According to the modified diene rubber obtained by the method for producing a modified diene rubber according to the present invention, a modified diene rubber composition excellent in low energy loss and rebound resilience can be obtained.

  Next, the rubber composition using the modified diene rubber according to the present invention will be described. The rubber composition according to the present invention is characterized by containing the modified diene rubber and silica.

  In the rubber composition according to the present invention, in addition to the modified diene rubber, other rubbers may be added and used as a rubber composition. There is no restriction | limiting in particular as rubber | gum other than that added, A well-known thing can be used. For example, polymers of diene monomers such as natural rubber, butadiene rubber (BR), syndiotactic-1,2-polybutadiene-containing butadiene rubber (VCR), isoprene rubber, butyl rubber, chloroprene rubber; acrylonitrile butadiene rubber ( NBR), acrylonitrile-diene copolymer rubber such as nitrile chloroprene rubber, nitrile isoprene rubber; styrene-diene copolymer rubber such as styrene butadiene rubber (SBR), styrene chloroprene rubber, styrene isoprene rubber; ethylene propylene diene rubber (EPDM), etc. Is mentioned. Of these, butadiene rubber, syndiotactic-1,2-polybutadiene-containing butadiene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, natural rubber, and isoprene rubber are preferable. These can be used alone or in combination of two or more.

  In the rubber composition according to the present invention, the content of silica is 10 to 120 parts by weight, more preferably 30 to 90 parts by weight with respect to 100 parts by weight of the modified diene rubber and other rubber components. Part by weight, particularly preferably 50 to 80 parts by weight. If the amount of silica is less than 10 parts by weight, sufficient silica dispersion can be obtained without using the modified diene rubber of the present invention. Therefore, the effect of the present invention is not obtained. In addition, wear resistance is also lowered, which is not preferable.

  Moreover, a rubber reinforcing agent can be added to the rubber composition according to the present invention. Examples of the rubber reinforcing agent include various types of carbon black, white carbon, activated calcium carbonate, ultrafine magnesium silicate and the like in addition to the above silica. Among them, preferably, carbon black having a particle size of 90 nm or less and dibutyl phthalate (DBP) oil absorption of 70 ml / 100 g or more, for example, FEF, FF, GPF, SAF, ISAF, SRF, HAF and the like are used. Particularly preferred is ISAF having a small particle size from the viewpoint of low heat build-up and low fuel consumption.

  When carbon black and silica used for the rubber reinforcing agent are mixed, it becomes possible to achieve both workability, low energy loss and wear. In particular, the weight ratio of carbon black / silica is preferably 90/10 to 10/90, more preferably 80/20 to 20/80, and particularly preferably 70/30 to 30/70. If the amount of silica is less than 10%, energy loss increases, and if it is more than 90%, there is a drawback that workability and wear resistance are deteriorated.

  Moreover, a vulcanizing agent and a vulcanization accelerator can be further added to the rubber composition according to the present invention.

  Examples of the vulcanizing agent include sulfur, a compound that generates sulfur by heating, a metal oxide such as an organic peroxide and magnesium oxide, a polyfunctional monomer, and a silanol compound. Examples of the compound that generates sulfur by heating include tetramethyl thiuram disulfide and tetraethyl thiuram disulfide.

  Examples of the vulcanization accelerator include aldehydes, ammonia, amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, xanthates, and more specifically, tetramethylthiuram disulfide. (TMTD), N-oxydiethylene-2-benzothiazolylsulfenamide (OBS), N-cyclohexyl-2-benzothiazylsulfenamide (CBS), dibenzothiazyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), zinc di-n-butyldithiocarbite (ZnBDC), zinc dimethyldithiocarbide (ZnMDC) and the like.

  Moreover, the rubber composition which concerns on this invention can add well-known additives normally used for rubber compositions, such as anti-aging agent, a filler, a process oil, as needed.

  Anti-aging agents include amine / ketone-based, imidazole-based, amine-based, phenol-based, sulfur-based and phosphorus-based anti-aging agents. More specifically, as the anti-aging agent, phenol-based 2,6-di-t-butyl-p-cresol (BHT), phosphorus-based trinonylphenyl phosphite (TNP), sulfur-based 4,6- Bis (octylthiomethyl) -o-cresol, dilauryl-3,3′-thiodipropionate (TPL) and the like can be mentioned.

  Examples of fillers include inorganic fillers such as calcium carbonate, basic magnesium carbonate, clay, Lissajous, diatomaceous earth, and other fillers such as recycled rubber and powder rubber. Process oils include aromatic and naphthenic fillers. And paraffinic process oil.

  Furthermore, a silane coupling agent may be added to the rubber composition according to the present invention. As the silane coupling agent, a silane coupling agent having a functional group capable of reacting with an epoxy group is particularly preferable.

  Examples of commercially available silane coupling agents having a functional group capable of reacting with an epoxy group include, but are not limited to, the following. 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, 3 -Aminopropyltriethoxysilane, 3-aminopropyldimethylbutoxysilane, 3-aminopropylmethyldibutoxysilane, 3- (2-aminoethylaminopropyl) dimethoxymethylsilane, 3- (2-aminoethylaminopropyl) dimethoxyethyl Silane, 3- (2-aminoethylaminopropyl) dimethoxypropylsilane, 3- (2-aminoethylaminopropyl) dimethoxybutylsilane, 3- (2-aminoethylaminopropyl) diethoxy Methylsilane, 3- (2-aminoethylaminopropyl) trimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane, 3- (2-aminoethylaminopropyl) tributoxysilane, 2- (3,4 -Epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, (3-mercaptopropyl) triethoxysilane, (3-mercaptopropyl) trimethoxysilane, (3-mercaptopropyl) methyldimethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 11- Mercaptoethyloleates undecyl trimethoxysilane, and the like 11 mercaptoundecyl triethoxysilane. Among these, (3-mercaptopropyl) triethoxysilane is particularly preferable.

  The addition amount of the silane coupling agent having a functional group capable of reacting with an epoxy group is preferably 0.1 to 1 molar equivalent with respect to the number of epoxy groups of the epoxidized diene rubber. When the addition amount of the silane coupling agent is less than 0.1 molar equivalent, the effect of improving tan δ and wear resistance tends to be reduced. Moreover, when the addition amount of the said silane coupling agent exceeds 1 molar equivalent, there exists a tendency which is not economically preferable.

  A rubber composition using a silane coupling agent functions to improve the dispersibility of the rubber reinforcing agent in the rubber matrix by mixing with a rubber reinforcing agent such as silica. As a result, it also leads to effects such as low fuel consumption.

  In the rubber composition according to the present invention, the maximum temperature during kneading using the banbury, open roll kneader, kneader, biaxial kneader, etc., in which each of the above components is usually performed, is the silane coupling agent and the epoxy group. It can be obtained by kneading under the condition of the reaction temperature or higher.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit the objective of this invention.

(Reference Example 1)
First, as Reference Example 1, epoxidized polybutadiene rubber used in Examples 1 to 4 and Comparative Examples 2 and 3 was prepared. Specifically, 100 g of polybutadiene (manufactured by Ube Industries, Ltd .: UBEPOL BR150L) was taken, put into 1000 ml of cyclohexane in a separable flask and stirred, and dissolved overnight (about 8 hours). Thereafter, the temperature of the separable flask was set to 50 ° C. in a water bath, and 1 g of nonionic surfactant Telic 320 (manufactured by HUNTSMAN) and 4.25 g of formic acid were added and stirred, followed by hydrogen peroxide solution (30%) 10 0.5 g was added with a dropping funnel and stirring was continued for 2 hours. Thereafter, the heating was stopped, 0.1 g of an antioxidant (Irganox 1520L) was added, and ice was added into the water bath to lower the temperature to room temperature. Next, 500 ml of methanol was added to precipitate epoxidized polybutadiene rubber from the solution. After removing the solvent, 500 ml of 2.5% sodium carbonate was added, and after stirring for 10 minutes, the washing solution was removed. Furthermore, 500 ml of water was added, and after stirring for 10 minutes, the washing solution was removed. This washing operation was performed three times. Thereafter, the reaction liquid was taken out into a vat coated with Teflon (registered trademark), placed in a vacuum dryer at 90 ° C. for 1 hour, and dried to obtain an epoxidized polybutadiene rubber.

  When the epoxidation rate of the obtained epoxidized polybutadiene rubber was measured, it was 2.2%.

  The epoxidation rate was measured according to JIS K7236 after storing for 3 hours or more after the completion of the sample process. The difference from JIS K7236 is that the amount of the epoxidized rubber was 0.6 g to 0.9 g, and that chloroform used for dissolving the epoxidized rubber was changed to cyclohexane. According to JIS K7236, 20 ml of acetic acid is added immediately before the measurement, but no acetic acid other than acetic acid contained in the tetraethylammonium bromide acetic acid solution is added. When a standard amount of acetic acid was added, a rubber having a low epoxidation rate was precipitated in a lump and could not be titrated. When the amount of acetic acid was reduced, the equivalence point became difficult to understand, but the precipitated sample spread on the measurement liquid in the form of an oil film, and titration became possible if time was taken. Other reagent adjustments are as described in JIS K7236.

  Moreover, the epoxidation rate was computed using the following formula 1 here. The epoxy equivalent is the mass (g) of the epoxidized resin corresponding to 1 mol of the epoxy group, and is determined by the method described in JIS K7236. In the case of 100% epoxidized polybutadiene, it is butadiene molecular weight + oxygen 1 atomic weight.

Example 1
Next, as shown in Table 1, 100 g of the epoxidized polybutadiene rubber produced in Reference Example 1 was taken, wound around a roll (temperature: 60 ° C., roll interval: 0.8 mm), and kneaded. As the roll, a 6-inch roll kneader manufactured by Yasuda Seiki was used. Next, 2.5 g of stearic acid (manufactured by Kao) and 1 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Kasei Co., Ltd .: reagent) are dropped on the epoxidized polybutadiene rubber on the roll with a pipette and further kneaded for 5 minutes. It was crowded. Then, the modified polybutadiene rubber which concerns on Example 1 was obtained by heat-processing at 90 degreeC under vacuum with a vacuum dryer for 1 hour. The modified polybutadiene rubber was allowed to stand for 24 hours, and about 5 g was taken, dissolved in 100 ml of cyclohexane and precipitated with ethanol twice. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 3.

(Example 2)
In Example 1, the modification according to Example 2 was performed in the same manner as in Example 1 except that 1 g of malonic acid (manufactured by Wako Pure Chemical Industries, Ltd .: reagent) was used instead of 2.5 g of stearic acid (manufactured by Kao Corporation). A polybutadiene rubber was obtained. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 1. The results are shown in Table 3.

(Example 3)
In Example 1, in the same manner as in Example 1, except that 2.5 g of malonic acid (manufactured by Wako Pure Chemical Industries, Ltd .: reagent) was used instead of 2.5 g of stearic acid (manufactured by Kao Corporation) Such modified polybutadiene rubber was obtained. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 1. The results are shown in Table 3.

Example 4
In Example 3, the modified polybutadiene rubber according to Example 4 was obtained in the same manner as in Example 3 except that the modified polybutadiene rubber was dissolved in 100 ml of cyclohexane and precipitated with ethanol once. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 3. The results are shown in Table 3.

(Comparative Example 1)
After allowing polybutadiene (manufactured by Ube Industries Ltd .: UBEPOL BR150L) to stand for 24 hours, about 5 g was taken, dissolved in 100 ml of cyclohexane, and precipitated with ethanol twice. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 3.

(Comparative Example 2)
After leaving the epoxidized polybutadiene rubber produced in Reference Example 1 for 24 hours, about 5 g was taken, dissolved in 100 ml of cyclohexane, and precipitated with ethanol twice. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 3.

(Comparative Example 3)
100 g of the epoxidized polybutadiene rubber produced in Reference Example 1 was taken, wound around a roll (temperature: 60 ° C., roll interval: 0.8 mm), and kneaded. As the roll, a 6-inch roll kneader manufactured by Yasuda Seiki was used. Next, 1 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Kasei Co., Ltd .: reagent) was dropped on the epoxidized polybutadiene rubber on the roll with a pipette and further kneaded for 5 minutes. Then, the modified polybutadiene rubber which concerns on the comparative example 3 was obtained by heat-processing at 90 degreeC for 1 hour under vacuum with a vacuum dryer. The modified polybutadiene rubber was allowed to stand for 24 hours, and about 5 g was taken, dissolved in 100 ml of cyclohexane and precipitated with ethanol twice. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 3.

30 parts by weight of the samples according to Examples 1 to 4 and Comparative Examples 1 to 3 obtained and 70 parts by weight of styrene-butadiene rubber (styrene content 23%, ML _{1 + 4} , 100 ° C. is 70) were previously added to 90 ° C. It was put into a heated 180 cc Banbury type plast mill and kneaded for 30 seconds. Next, 75 parts by weight of silica (Ultrasil 5000GR), 6 parts by weight of a silane coupling agent (Si69), 21.5 parts by weight of process oil (Sansen Oil 4240), 3 parts by weight of zinc oxide, an anti-aging agent (manufactured by Sumitomo Chemical: 1 part by weight of Antigen 6C) and 1 part by weight of stearic acid were mixed, half of which was put into a plastmill and kneaded for 1 minute. Next, the remaining half was charged and kneaded for about 3 minutes 30 seconds. After a total of 5 minutes from the start of kneading, the kneaded product was taken out from the plast mill. Next, while winding the mixture taken out on a 6-inch roll and kneading the roll, 1.4 parts by weight of powdered sulfur as a vulcanizing agent, 1.7 parts by weight of a vulcanization accelerator Noxeller CZ and 2 parts by weight of Noxeller D are added. did. The roll temperature was 60 ° C., and powdered sulfur and a vulcanization accelerator were mixed for about 5 minutes. Next, vulcanization molding was performed in order to obtain a vulcanization molding necessary for the test described below. Using a mold set in a hot press, the mixture was placed in the mold, and vulcanization molding was performed by heating and pressurizing at a temperature of 160 ° C. for about 20 to 25 minutes, to Examples 1 to 4 and Comparative Examples 1 to 3 Such a rubber composition was obtained. Table 2 shows the chemicals used and the mixing ratio (parts by weight).

  For the rubber compositions according to Examples 1 to 4 and Comparative Examples 1 to 3 obtained, the tensile strength, fracture elongation, rebound resilience, and vulcanized product tan δ of the rubber composition were measured by the following methods. The results are shown in Table 3.

(Tensile test)
Measurement was performed according to JIS K6251 and tensile strength (TB), elongation at break (EB), and (TB × EB) / 2 were expressed as an index using the following formula 2. (TB × EB) / 2 indicates the approximate amount of energy expended before breaking. TB, EB, (TB × EB) / 2 is generally more advantageous as a rubber composition as the index is larger.

(Rebound resilience test)
The impact resilience was measured by a trypso method according to the measurement method defined in JIS K6251 and expressed as an index using the following formula 2. Generally, the larger the index, the more advantageous as a rubber composition.

(Vulcanized product tan δ)
Using EPLEXOR 100N (manufactured by GABO), tan δ of each formulation was measured under the measurement conditions of initial strain 10%, dynamic strain 0.3%, frequency 16 Hz, temperature 50 ° C., and tan δ of Comparative Example 1 was set to 100. The index is expressed by the following formula 3. The larger the index, the better the rolling resistance characteristics.

  From the above, it can be seen that the modified polybutadiene rubber according to the example has a large amount of Si reacted with the epoxy group, so that the dispersibility of silica is improved, and as a result, the tan δ and rebound resilience of the rubber composition are improved.

(Reference Example 2)
Next, as Reference Example 2, epoxidized polybutadiene rubber used in Examples 5 to 10 and Comparative Example 4 was produced. Specifically, 100 g of polybutadiene (manufactured by Ube Industries, Ltd .: UBEPOL BR150L) is taken, put into 1000 ml of cyclohexane in a separable flask and stirred, and then overnight (about 8 hours at room temperature (25 ° C.)). ) To dissolve. Thereafter, the temperature of the separable flask was adjusted to 40 ° C. in a water bath, 1 g of nonionic surfactant terrick 320 (manufactured by HUNTSMAN) and 2.13 g of formic acid were added and stirred, and then the temperature of the separable flask was increased to 50 ° C. Then, 5.24 g of hydrogen peroxide solution (30%) was added through a dropping funnel and stirring was continued for 2 hours. Thereafter, the heating was stopped, 0.2 g of an antioxidant (Irganox 1520L) was added, and ice was added into the water bath to lower the temperature to room temperature. Next, 500 ml of ethanol was added and epoxidized polybutadiene rubber was precipitated from the solution. After removing the solvent, 500 ml of 1.0% sodium carbonate was added, and after stirring for 10 minutes, the washing solution was removed. Furthermore, 500 ml of water (pH = 7.0) was added, and after stirring for 10 minutes, the washing solution was removed. This washing operation was performed three times. Thereafter, the reaction solution was taken out into a Teflon (registered trademark) -coated vat, placed in a vacuum dryer at 90 ° C. for 3 hours, and dried to obtain an epoxidized polybutadiene rubber.

  When the epoxidation rate of the obtained epoxidized polybutadiene rubber was measured in the same manner as in Reference Example 1, it was 2.5%.

(Example 5)
Next, as shown in Table 4, 100 g of the epoxidized polybutadiene rubber produced in Reference Example 2 was taken, wound around a roll (temperature: 60 ° C., roll interval: 0.8 mm), and kneaded. As the roll, a 6-inch roll kneader manufactured by Yasuda Seiki was used. Next, 1 g of stearic acid (manufactured by Kao Corporation) and 1 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Chemical Industry: Reagent) were hung on the epoxidized polybutadiene rubber on the roll with a pipette and further kneaded for 5 minutes. . Then, the modified polybutadiene rubber which concerns on Example 5 was obtained by heat-processing at 90 degreeC under vacuum with a vacuum dryer for 1 hour. After this modified polybutadiene rubber was allowed to stand for 24 hours, about 5 g was taken and dissolved in 120 ml of cyclohexane and washed with 400 ml of methanol for 30 minutes. The precipitated sample was dissolved again in 120 ml of cyclohexane, 0.05 ml of an anti-aging agent (Irganox 1520L) was added, and the sample was precipitated again by washing with methanol in the same manner as described above. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 6.

(Example 6)
A modified polybutadiene rubber according to Example 6 in the same manner as in Example 5 except that 1 g of malonic acid (manufactured by Wako Pure Chemical Industries, Ltd .: reagent) was used instead of 1 g of stearic acid (manufactured by Kao Corporation) in Example 5. Got. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 5. The results are shown in Table 6.

(Example 7)
In Example 5, the modification according to Example 7 was performed in the same manner as in Example 5 except that 2.5 g of malonic acid (manufactured by Wako Pure Chemical Industries, Ltd .: reagent) was used instead of 1 g of stearic acid (manufactured by Kao Corporation). A polybutadiene rubber was obtained. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 5. The results are shown in Table 6.

(Comparative Example 4)
100 g of the epoxidized polybutadiene rubber produced in Reference Example 2 was taken, wound around a roll (temperature: 60 ° C., roll interval: 0.8 mm), and kneaded. As the roll, a 6-inch roll kneader manufactured by Yasuda Seiki was used. Next, 1 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Kasei Co., Ltd .: reagent) was dropped on the epoxidized polybutadiene rubber on the roll with a pipette and further kneaded for 5 minutes. Then, the modified polybutadiene rubber which concerns on the comparative example 4 was obtained by heat-processing at 90 degreeC under vacuum with a vacuum dryer for 1 hour. After this modified polybutadiene rubber was allowed to stand for 24 hours, about 5 g was taken and dissolved in 120 ml of cyclohexane and washed with 400 ml of methanol for 30 minutes. The precipitated sample was dissolved again in 120 ml of cyclohexane, 0.05 ml of an anti-aging agent (Irganox 1520L) was added, and the sample was precipitated again by washing with methanol in the same manner as described above. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 6.

(Example 8)
Next, as shown in Table 5, 100 g of the epoxidized polybutadiene rubber produced in Reference Example 2 was taken, wound around a roll (temperature: 60 ° C., roll interval: 0.8 mm), and kneaded. As the roll, a 6-inch roll kneader manufactured by Yasuda Seiki was used. Next, 1 g of malonic acid (manufactured by Kao Co., Ltd.) and 2.5 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Kasei Co., Ltd .: reagent) are pipetted onto the epoxidized polybutadiene rubber on the roll and kneaded for 5 minutes. It was crowded. Then, the modified polybutadiene rubber which concerns on Example 8 was obtained by heat-processing at 90 degreeC under vacuum with a vacuum dryer for 1 hour. After this modified polybutadiene rubber was allowed to stand for 24 hours, about 5 g was taken and dissolved in 120 ml of cyclohexane and washed with 400 ml of methanol for 30 minutes. The precipitated sample was dissolved again in 120 ml of cyclohexane, 0.05 ml of an anti-aging agent (Irganox 1520L) was added, and the sample was precipitated again by washing with methanol in the same manner as described above. The obtained sample was again dried at 90 ° C. for 1 hour, and the Si content was measured by ICP analysis. The results are shown in Table 6.

Example 9
A modified polybutadiene rubber according to Example 9 was obtained in the same manner as in Example 8, except that 5 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Chemical Industry: Reagent) was used. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 8. The results are shown in Table 6.

(Example 10)
In Example 8, 2.5 g of APTES (3-aminopropyltriethoxysilane) (manufactured by Tokyo Chemical Industry: reagent) instead of 2.5 g of GOPTMS (3-glycidyloxypropyltrimethoxysilane) (manufactured by Tokyo Chemical Industry: reagent) A modified polybutadiene rubber according to Example 10 was obtained in the same manner as Example 8 except that it was used. About the obtained sample, the content of Si was measured by ICP analysis in the same manner as in Example 8. The results are shown in Table 6.

30 parts by weight of the samples according to Examples 5 to 10 and Comparative Example 4 and 70 parts by weight of styrene-butadiene rubber (styrene content is 23%, ML _{1 + 4} , 100 ° C. is 70) are heated to 90 ° C. in advance. It was put into a 180 cc Banbury type plast mill and kneaded for 30 seconds. Next, 75 parts by weight of silica (Nipsil AQ), 6 parts by weight of a silane coupling agent (Evonik Degussa Japan: Nibonic Degussa Si69), 21.5 parts by weight of process oil (Sansen Oil 4240), 3 parts by weight of zinc oxide, aging 1 part by weight of an inhibitor (manufactured by Sumitomo Chemical Co., Ltd .: Antigen 6C) and 1 part by weight of stearic acid (manufactured by Kao Corporation) were mixed, half of which was put into a plastmill and kneaded for 1 minute. Next, the remaining half was charged and kneaded for about 3 minutes 30 seconds. After a total of 5 minutes from the start of kneading, the kneaded product was taken out from the plast mill. Next, while winding the mixture taken out on a 6-inch roll and roll kneading, 1.4 parts by weight of powdered sulfur as a vulcanizing agent, 1.7 parts by weight of a vulcanization accelerator Noxeller CZ (CBS) and Noxeller D 2 parts by weight of (DPG) was added. The temperature of the roll was 55 to 65 ° C., and powdered sulfur and a vulcanization accelerator were mixed for about 5 minutes. Next, vulcanization molding was performed in order to obtain a vulcanization molding necessary for the test described below. Rubbers according to Examples 5 to 10 and Comparative Example 4 were performed by using a mold set in a hot press, and performing a vulcanization molding by putting the mixture in the mold and heating and pressing at a temperature of 160 ° C. for about 20 to 25 minutes. A composition was obtained.

  For the rubber compositions according to 5 to 10 and Comparative Example 4 obtained, the tensile strength, fracture elongation, impact resilience, and vulcanized product tan δ of the rubber composition were the same as those in Examples 1 to 4 and Comparative Examples 1 to 3. Measured by the method. The results are shown in Table 6.

From the above, it can be seen that the modified polybutadiene rubber according to the example has a large amount of Si reacted with the epoxy group, so that the dispersibility of silica is improved, and as a result, the tan δ and rebound resilience of the rubber composition are improved.

Claims (4)

  A modified diene rubber obtained by reacting an epoxidized diene rubber having an epoxidation rate of 0.1% or more and less than 15%, an alkoxysilane having a functional group that reacts with an epoxy group, and a carboxylic acid.   The modified diene rubber according to claim 1, wherein the reaction is carried out at 20 to 140 ° C.   A modified diene system characterized by reacting an epoxidized diene rubber having an epoxidation ratio of 0.1% or more and less than 15%, an alkoxysilane having a functional group that reacts with an epoxy group, and a carboxylic acid by mechanical kneading. Rubber production method. A modified diene rubber composition comprising the modified diene rubber according to claim 1 or 2 and silica.