JP4782486B2 - Rubber composition and method for producing the same - Google Patents

Description

  The present invention relates to a rubber composition used for molding a rubber product and a method for producing the same.

As a method of compounding silica as a reinforcing agent in rubber, for example, a so-called kneading method is used in which kneading is performed using a Banbury mixer, an open roll, a kneader, or the like.
However, since silica has a silanol group on its surface and exhibits hydrophilicity, it generally has low affinity with rubber that exhibits hydrophobicity. Moreover, since silica has a strong self-aggregation property, it is not easy to uniformly disperse silica in rubber.

On the other hand, Patent Document 1 proposes a method for producing a coarsely vulcanizable mixture by coprecipitation of a mixture of water glass and rubber latex using an acid.
Patent Document 2 discloses an organic-inorganic hybrid composed of a rubber main body having an ethylene group and a side chain bonded to the rubber main body and having a pyridinium salt of silanol at the terminal. , Rubbers (silicic acid PSBR) compounded with silicic acid prepared from water glass and 2-vinylpyridine-styrene-butadiene copolymer rubber are described, respectively. It has been shown to have characteristics such as low hysteresis loss.
JP 47-1090 A Japanese Patent Laid-Open No. 11-255843 "Composition using water glass-Preparation and physical properties of 2-vinylpyridinium silicate-styrene-butadiene copolymer rubber", Kobunshi Ronbunshu, Vol. 59, No. 1, p. 15-20 (January 2002)

  However, the vulcanizable mixture obtained by the method described in Patent Document 1 is a coarse granular material having a particle diameter of about 2 to 3 mm. For example, this mixture is blended as a reinforcing agent in the raw rubber. In order to obtain a uniform dispersed state, it is necessary to reduce the particle size of the mixture by pulverization or the like in advance. Further, even when the above mixture is used as a molding material for rubber products, it is necessary to dry and grind the coarsely granular mixture. Therefore, using the above vulcanizable mixture requires extra labor and cost.

  On the other hand, in the invention described in Patent Document 2, in order to obtain an organic-inorganic hybrid, water glass or the like is acid-treated, and then silanol is extracted with an organic solvent (tetrahydrofuran). A pyridine ring protruding from the side chain is bound as a pyridinium salt. However, in this case, in order to obtain an organic-inorganic hybrid, a large amount of an organic solvent and a large number of steps are required, so that improvements from the manufacturing cost and environmental aspects are desired. In addition, the rubber (silicic acid PSBR) described in Non-Patent Document 1 is also obtained by dissolving water glass in an acid treatment and then dissolving in tetrahydrofuran (THF), and the THF solution thus obtained and a vinylpyridine-styrene-butadiene copolymer. Since it is synthesized by reacting with rubber latex, as in the case of Patent Document 1, improvement from the environmental aspect is desired.

  Moreover, since the organic-inorganic hybrid described in Patent Document 2 and the silicic acid PSBR described in Non-Patent Document 1 have high hardness and have a pyridinium group in the molecule, styrene-butadiene rubber (SBR), etc. There is a large difference in polarity with the general-purpose raw rubber. Therefore, it is difficult to uniformly disperse the above organic-inorganic hybrid and silicic acid PSBR in the raw rubber by dry blending. Furthermore, the above organic-inorganic hybrid and silicic acid PSBR are likely to exist as aggregates in the raw rubber, and this aggregate serves as a starting point for causing damage inside the rubber molded body. There is a possibility of causing a problem that the mechanical strength is lowered.

  Accordingly, an object of the present invention is to provide a rubber composition for obtaining a rubber product excellent in mechanical properties such as mechanical strength and hysteresis loss, and a method capable of producing the rubber composition by a simple method. Is to provide.

In order to achieve the above object, the present invention provides:
(1) It is obtained by coagulating a latex containing different types of rubber (A) and rubber (B) and water glass with an acid or salt, and the rubber (A) contains pyridyl groups in the molecule. And at least one functional group selected from the group consisting of a carboxyl group, an amino group, a carbamoyl group, an N-hydroxymethylcarbamoyl group and an epoxy group, and the rubber (B) is a rubber (B) alone the a latex all SANYO to produce a batter processible rubbers when solidified with an acid or salt in the coexistence of water glass, the mixing ratio of the rubber (a) and the rubber (B), 5: 95-97: 3 der Rukoto characterized, rubber composition,
(2) The rubber (A) has at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group, an amino group, a carbamoyl group, an N-hydroxymethylcarbamoyl group and an epoxy group in the molecule. The rubber composition according to (1), wherein the rubber composition is a diene rubber,
(3) The rubber composition according to (2), wherein the diene rubber is a copolymer of styrene and butadiene,
(4) The rubber composition according to (1), wherein the rubber (A) is an epoxidized natural rubber,
(5) The rubber (B) is a rubber that does not have any functional group of pyridyl group, carboxyl group, amino group, carbamoyl group, N-hydroxymethylcarbamoyl group and epoxy group in the molecule. The rubber composition according to any one of (1) to (4),
(6) The rubber (B) has at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group and an epoxy group in the molecule. 4) The rubber composition according to any one of
(7) Rubber (A) latex having in the molecule at least one functional group selected from the group consisting of pyridyl group, carboxyl group, amino group, carbamoyl group, N-hydroxymethylcarbamoyl group and epoxy group And a rubber (B) latex that is different in type from the rubber (A) and produces a rubber that can be kneaded when coagulated with an acid or salt in the presence of water glass, and water glass. Are blended so that the blending ratio of the rubber (A) and the rubber (B) is 5:95 to 97: 3, and the blended latex is prepared. A method for producing a rubber composition, characterized by coagulating with a salt;
Is to provide.

  The rubber composition of the present invention can be obtained by a simple method in which a compounded latex containing water glass is coagulated with an acid or a salt. Moreover, the compound of the silicate component and the rubber (A) produced from water glass can be uniformly dispersed throughout the rubber composition by kneading together with the rubber (B). By using the obtained rubber composition of the present invention, it becomes possible to mold and produce a rubber product excellent in mechanical strength and mechanical properties.

  Further, according to the method for producing a rubber composition of the present invention, it is possible to achieve a composite of a silicic acid component produced from water glass and a rubber without using an organic solvent and by a simple treatment. it can.

The rubber composition of the present invention is obtained by coagulating a compounded latex containing different rubbers (A) and (B) and water glass with an acid or a salt.
The rubber (A) is a rubber that interacts with a silicic acid component (silanol group) produced from water glass, and includes pyridyl group, carboxyl group, amino group, carbamoyl group, N-hydroxymethyl in the molecule. Examples thereof include those having at least one functional group selected from the group consisting of a carbamoyl group and an epoxy group. These rubbers that interact with silicic acid components (silanol groups) produced from water glass may be a mixture of two or more rubbers.

  Rubber of “Rubber having at least one functional group selected from the group consisting of pyridyl group, carboxyl group, amino group, carbamoyl group, N-hydroxymethylcarbamoyl group and epoxy group in the molecule” (the above functional group For example, SBR (a copolymer of styrene and butadiene; styrene-butadiene rubber), SBIR (a copolymer of styrene, isoprene, and butadiene), MSBR (α-methylstyrene and butadiene) Copolymer), bromide of copolymer of p-methylstyrene and isobutylene, NBR (copolymer of acrylonitrile and butadiene; acrylonitrile-butadiene rubber), NBIR (copolymer of acrylonitrile, butadiene and isoprene) ), NIR (copolymerization of acrylonitrile and isoprene) ), NR (natural rubber), IR (isoprene rubber), IIR (copolymer of isobutene and isoprene; butyl rubber), BR (butadiene rubber), CR (chloroprene rubber), EPDM (copolymer of ethylene, propylene and diene) Polymer). Of these, diene rubbers such as SBR, NBR, NR, IR, IIR and BR are preferable, and NR and SBR are more preferable.

  The pyridyl group is present as a monomer unit having a pyridyl group in the rubber molecule. Examples of the monomer having a pyridyl group include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-allylpyridine and the like. Examples of rubber having a pyridyl group in the molecule (pyridine-modified rubber) include, for example, PSBR (a copolymer of vinylpyridine, styrene, and butadiene), carboxylated PSBR (PSBR having a carboxyl group in the molecule; carboxy-modified) PSBR), amino-modified PSBR (PSBR having an amino group in the molecule), amide-modified PSBR (PSBR having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule), PBR (copolymer of vinylpyridine and butadiene) Etc. Especially, PSBR, carboxylated PSBR, etc. are mentioned preferably, More preferably, carboxylated PSBR is mentioned.

  The pyridyl group content of the pyridine-modified rubber (weight ratio of monomer units having a pyridyl group (for example, vinylpyridine) in the pyridine-modified rubber) is not particularly limited, but is preferably 2% by weight or more, more preferably Is 3% by weight or more, more preferably 10 to 20% by weight. When the content of the pyridyl group is less than 2% by weight, the number of sites that interact with the silicic acid component (silanol group) generated from water glass is reduced, and as a result, the rubber (A) is provided with desired characteristics. There is a risk that the effect of improving the mechanical strength and mechanical properties of the rubber composition may be insufficient.

  Examples of rubber having a carboxyl group in the molecule (carboxy-modified rubber) include XSBR (a copolymer of carboxylated styrene and butadiene), XNBR (a copolymer of carboxylated acrylonitrile and butadiene), Carboxylated PSBR (carboxy-modified PSBR), amino-modified XSBR (XSBR having an amino group in the molecule), amide-modified XSBR (XBR having a carbamoyl group or an N-hydroxymethylcarbamoyl group in the molecule), XBR (carboxylated) Butadiene rubber), XCR (carboxylated chloroprene rubber), amide-modified XSBR (XSBR having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule), etc., preferably XSBR, carboxylated SBR, and an amino-modified XSBR is.

  The carboxyl group content of the carboxy-modified rubber (weight ratio of carboxyl groups (—COOH) in the entire rubber molecule of the carboxy-modified rubber) is not particularly limited, but is preferably 0.5% by weight or more, more preferably 3%. % By weight or more, more preferably 4 to 20% by weight. When the carboxyl group content is less than 0.5% by weight, the number of sites that interact with the silicic acid component (silanol group) generated from water glass decreases, and as a result, the rubber (A) has desired characteristics. May not be imparted, and the effect of improving the mechanical strength and mechanical properties of the rubber composition may be insufficient.

  Examples of rubber having an amino group in the molecule (amino-modified rubber) include, for example, amino-modified SBR (SBR having an amino group in the molecule), amino-modified XSBR, amino-modified PSBR, and amino-modified NBR (amino group in the molecule). NBR), amino-modified IR (IR having an amino group in the molecule), amino-modified IIR (IIR having an amino group in the molecule), amino-modified BR (BR having an amino group in the molecule), and the like. Of these, amino-modified SBR, amino-modified XSBR, and the like are preferable, and amino-modified XSBR is more preferable.

The amino group content of the amino-modified rubber (weight ratio of amino groups (—NH ₂ ) in the whole rubber molecule of the amino-modified rubber) is not particularly limited, but is preferably 1% by weight or more, more preferably 2% by weight. % Or more, more preferably 2 to 20% by weight. When the amino group content is less than 1% by weight, the number of sites that interact with the silicic acid component (silanol group) generated from water glass is reduced, and as a result, the rubber (A) is provided with desired characteristics. There is a risk that the effect of improving the mechanical strength and mechanical properties of the rubber composition may be insufficient.

  Examples of the rubber having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule (amide-modified rubber) include, for example, SBR having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule (amide-modified SBR), amide-modified XSBR, Amide-modified PSBR, NBR having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule (amide-modified NBR), IR having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule (amide-modified IR), carbamoyl in the molecule Group or N-hydroxymethylcarbamoyl group IIR (amide-modified IIR), BR having carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule (amide-modified BR), carbamoyl group or N-hyphene in the molecule Amino-modified SBR having a roxymethylcarbamoyl group (amino-amide-modified SBR), amino-modified XSBR having a carbamoyl group or N-hydroxymethylcarbamoyl group in the molecule (amino-amide-modified XSBR), a carbamoyl group or N- in the molecule Examples include amino-modified PSBR (amino-amide-modified PSBR) having a hydroxymethylcarbamoyl group. Of these, amide-modified SBR, amide-modified XSBR, and the like are preferable, and amide-modified SBR is more preferable.

The carbamoyl group or N-hydroxymethylcarbamoyl group content of the amide-modified rubber (weight ratio of carbamoyl group (—CONH ₂ ) or N-hydroxymethylcarbamoyl group (—CONHCH ₂ OH) in the entire rubber molecule of amino-modified rubber) is Although not particularly limited, it is preferably 2% by weight or more, more preferably 3% by weight or more, and further preferably 4 to 20% by weight. When the content is less than 2% by weight, the number of sites that interact with the silicic acid component (silanol group) generated from water glass decreases, and as a result, the rubber (A) cannot be provided with desired characteristics. Or the effect of improving the mechanical strength and mechanical properties of the rubber composition may be insufficient.

Examples of rubber (epoxy-modified rubber) having an epoxy group in the molecule include ENR (epoxidized natural rubber).
The epoxidation rate of the epoxy-modified rubber (ratio in which an epoxy group (epoxy ring) is introduced into a double bond in the rubber molecule) is not particularly limited, but is preferably 3 to 70 mol%, more preferably 5 It is -65 mol%, More preferably, it is 7-60 mol%. When the epoxidation rate is less than 3 mol%, the number of sites that interact with the silicic acid component (silanol group) generated from water glass decreases, and as a result, the rubber (A) cannot be provided with desired characteristics. Or the effect of improving the mechanical strength and mechanical properties of the rubber composition may be insufficient. On the contrary, when the epoxidation rate exceeds 70 mol%, the rubber (A) becomes too sticky, the rubber elasticity of the rubber composition is impaired, the glass transition point becomes too high, and the temperature is low. There is a risk that the durability at the time may decrease, and there is a risk that mechanical blending becomes difficult due to adhesion to the inner wall of a kneader or the like.

  The rubber having at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group, an amino group, a carbamoyl group, an N-hydroxymethylcarbamoyl group and an epoxy group in the molecule is among those exemplified above. Particularly preferred are XSBR, carboxylated PSBR, amino-modified XSBR, amide-modified SBR, ENR and the like. In addition, as illustrated above, the rubber (A) may include two or more functional groups illustrated above.

  The rubber (A) cannot be kneaded by itself depending on the type of functional group that the rubber (A) has, the processing conditions for coagulating the latex in the presence of water glass (for example, It may be obtained as a rubber composition in the form of a fine powder. However, as will be described later, the rubber (B) contained in the compounded latex is a rubber that can be kneaded even when the latex is coagulated with an acid or salt in the presence of water glass. Since the rubber (A) latex is coagulated with an acid or salt in the presence of water glass, a rubber composition in the form of a fine powder is generated. However, the rubber composition as a whole can be kneaded.

Further, even when the latex of rubber (A) is coagulated with an acid or salt in the presence of water glass, even if a fine powdery rubber composition is produced, this finely powdered rubber composition is In the rubber (B), which will be described later, it is uniformly dispersed, and is dispersed in a fine powder state without agglomeration.
In the present invention, “kneading is possible” means that the solidified product obtained by coagulation with an acid or salt is put into a roll or Banbury mixer and subjected to kneading such as mastication. In the above, even after kneading, the coagulated product can maintain a unified form as an unvulcanized compounded rubber.

The rubber (B) is not particularly limited, except that when the latex of the rubber is coagulated with an acid or salt in the presence of water glass, a rubber that can be kneaded is produced. Whether or not to interact with a silicic acid component (silanol group) produced from water glass is not limited.
Examples of the rubber (B) include NR, SBR, XSBR, amino-modified XSBR, SBIR, MSBR, IR, IIR, BR, CR, EPDM, and the like. Preferably, NR, SBR, XSBR, or amino-modified XSBR is used. Can be mentioned.

Even if the rubber (B) exemplified above is not supplied as a latex, for example, the rubber (B) is dissolved in an appropriate solvent and dispersed in water, and then the solvent is stripped to form a latex. By doing so, it can be used in the present invention.
The rubber (B) may contain two or more of the rubbers exemplified above.
The rubber (B) generates rubber that cannot be kneaded (for example, in the form of fine powder) when the latex of the rubber is coagulated with acid or salt in the presence of water glass. In some cases, when the compounded latex containing the rubber (A), the rubber (B), and water glass is coagulated with an acid or salt, both the rubber (A) and the rubber (B) are There is a possibility that it may be finely powdered. As a result, the rubber composition of the present invention may be unable to be molded alone.

Since the rubber composition of the present invention includes not only the rubber (A) described above but also a rubber (B) that is different from the rubber (A), it cannot be obtained with only one type of rubber. Physical properties can be expressed.
The blending ratio of the rubber (A) and the rubber (B) can be appropriately set according to the physical properties required for the rubber composition, and is not particularly limited. Usually, the rubber (A) and the rubber (B) The ratio is preferably 5:95 to 97: 3 (weight ratio), and more preferably 10:90 to 95: 5 (weight ratio).

The water glass is usually represented by a composition represented by the following formula.
Na ₂ O · nSiO ₂ · mH ₂ O
The coefficient n is a value represented by a molecular ratio of SiO ₂ / Na ₂ O, and is a range specified in (JIS K 1408 _-1966 ), generally called a molar ratio. Although this coefficient n is not specifically limited, Preferably it is 2.1-3.1, More preferably, it is 3.1. When the coefficient n is 3.1, the content of the silicic acid component in the water glass (in terms of SiO ₂ ) increases, so that the efficiency of the composite treatment with rubber is improved.

In general, the water glass having the coefficient n of 3.1 is commercially available as water glass No. 3. The water glass which can be used for this invention is not limited to this, For example, the 1-3 water glass prescribed | regulated to JISK1408, and other various grade products can be used.
The amount of water glass, for the silicic acid component generated from the water glass, the content of a rubber composition (SiO ₂ equivalent amount) may be set to be in the range described below.

In the rubber composition, the content of the silicic acid component produced from the water glass (in terms of SiO ₂ ) is that of the rubber (A) interacting with the silicic acid component (silanol group) produced from the water glass. The amount is 1 to 50 parts by weight, preferably 3 to 40 parts by weight, and more preferably 5 to 35 parts by weight with respect to the total amount of 100 parts by weight. If the content of the silicic acid component (SiO ₂ equivalent amount) is less than 1 part by weight with respect to 100 parts by weight of the total amount of the rubber, it becomes difficult to obtain the effect associated with blending of water glass. Conversely, if the content of the silicic acid component (in terms of SiO ₂ ) exceeds 50 parts by weight with respect to 100 parts by weight of the total amount of rubber, water glass that is not involved in the interaction between the rubbers is produced. Glass is wasted. Furthermore, in this case, a silicic acid component (silica) having a large particle size is likely to be generated, and the silicic acid component (silica) having a large particle size serves as a nucleus of destruction and reduces the mechanical strength of the rubber composition. There is a risk of causing.

Examples of the acid for coagulating the compounded rubber latex include sulfuric acid and hydrochloric acid, and preferably sulfuric acid.
Examples of the salt for coagulating the compounded rubber latex include metal salts, and more specifically, calcium salts such as calcium nitrate and calcium chloride. Although not limited to this, the valence of the salt is preferably divalent or trivalent.

The rubber composition of the present invention is prepared by blending the latex of the rubber (A), the latex of the rubber (B), and water glass to prepare a blended latex, and then adding the acid or salt to the resulting blended latex. Can be obtained by blending and coagulating the blended latex.
The compounded latex may be prepared by mixing the latex of the rubber (A) and the latex of the rubber (B) and then blending with water glass. The latex of one of the rubber (A) and the rubber (B) After mixing water and water glass, the other rubber latex may be blended.

The rubber solid content concentration of the latex of the rubber (A) and the rubber (B) is not particularly limited, and may be appropriately set from the viewpoint of handleability. Usually, the rubber solid content concentration is suitably set to 30 to 60% by weight.
It is preferable that the acid or salt is added to the compounded latex while the compounded latex is stirred and the acid, salt or aqueous solution thereof is slowly added dropwise.

Although it does not specifically limit as conditions at the time of mix | blending an acid or a salt with compounded latex, For example, the temperature of compounded latex becomes like this. Preferably it is 10-90 degreeC, More preferably, it is 20-70 degreeC.
The rubber composition obtained by coagulating the compounded latex is prepared, for example, by blending a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, etc. by a conventional method, and then adding the resulting blended rubber by a conventional method. Various rubber products can be obtained by molding and molding.

  Although it does not specifically limit about the specific use of the rubber product obtained using the rubber composition of this invention, For example, a damper etc. are mentioned.

Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example.
The components used in Examples and Comparative Examples are as follows.
SBR latex: total solid content 70.0%, trade name “Nipol C4380A”, manufactured by Nippon Zeon Co., Ltd. Carboxylated PSBR latex: carboxy-modified PSBR latex, total solid content 36.0%, butadiene: styrene: vinyl pyridine = 70:15:15 (weight ratio of monomer units), carboxyl group content 0.5-4% by weight, trade name “Nipol LX603”, manufactured by Nippon Zeon Co., Ltd., XSBR latex: 50% total solids , Carboxyl group content 2-30% by weight, trade name “Nipol SR400”, manufactured by Nippon Zeon Co., Ltd., amino-modified XSBR latex: total solid content 43%, amino group content 0.5-5% by weight, carboxyl group Content of about 0.5-4% by weight, trade name “Nipol LX407K3”, manufactured by Nippon Zeon Co., Ltd., amide-modified SBR Latex: Total solid content 41%, N-hydroxymethylcarbamoyl group content 0.5-6% by weight, trade name "Nipol LX432M", manufactured by Nippon Zeon Co., Ltd. NR latex: high ammonia type, rubber content 60%
-ENR latex: 30% rubber content, 50% epoxidation rate
Water Glass: water glass No. 3 _{(Na 2 O · nSiO 2 ·} mH 2 O, n = 3.2), the content of the silicic acid component (silica) (SiO ₂ equivalent amount) of 28% equivalent, Fuji Chemical (Co. ) Made of powdered sulfur: Powdered (200 mesh) sulfur, vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), trade name “Noxeller CZ”, Ouchi Shinsei Chemical Industry ( Co., Ltd., Vulcanization Accelerator D: Trade name “Soccinol D”, manufactured by Sumitomo Chemical Co., Ltd.
Example 1
Carboxylated PSBR latex and NR latex were mixed such that the respective rubber components were in a weight ratio of 50:50 to obtain a mixed latex. Subsequently, water glass was mix | blended with the obtained mixed latex, and the mixing | blending latex was obtained by stirring for 1 hour. The blending amount of the water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ conversion amount) was 10 parts by weight with respect to 100 parts by weight of the carboxylated PSBR.

  Next, the blended latex was slowly dropped into 2N-sulfuric acid, and the coagulum thus obtained was immersed in ion-exchanged water for a whole day and washed. The ion exchange water was changed several times. Further, the coagulated product was molded into a thin sheet while being washed with a water squeezing roll, and dried in an oven at 40 ° C. to obtain a rubber composition (silicic acid-carboxylated PSBR / NR).

A part of the obtained rubber composition was put in a crucible, heated at 650 ° C. for 1 hour, incinerated, and the amount of ash remaining was measured, whereby the silicic acid component (silica) in 100 parts by weight of the rubber composition was measured. When the content was calculated, it was 4.8 parts by weight in terms of SiO ₂ .
Next, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1.5 parts by weight of powdered sulfur, 1.0 part by weight of a vulcanization accelerator (CBS) and a vulcanization accelerator with respect to 105 parts by weight of the rubber composition. (D) 0.6 weight part was mix | blended and the compounded rubber was obtained by kneading | mixing with a kneading machine (kneading test apparatus mix laboratory, the product made by Moriyama Corporation).

Further, this compounded rubber was formed into a sheet shape and press vulcanized at 170 ° C. to obtain a vulcanized rubber sheet having a thickness of 2 mm. The vulcanization time is calculated based on a time-torque curve (vulcanization curve) at a vulcanization temperature of 170 ° C. prepared in advance for the compounded rubber using a curast meter. The time required to reach 90% (T ₉₀ ) was used.

Example 2
Amino-modified XSBR latex and NR latex were mixed such that the respective rubber components were in a weight ratio of 50:50 to obtain a mixed latex. Subsequently, water glass was mix | blended with the obtained mixed latex, and the mixing | blending latex was obtained by stirring for 1 hour. The amount of water glass blended was adjusted so that the amount of silicic acid component produced from the water glass (SiO ₂ equivalent) was 10 parts by weight with respect to 100 parts by weight of the amino-modified XSBR.

Next, a thin sheet-like rubber composition (silicic acid-amino-modified XSBR / NR) was obtained in the same manner as in Example 1 except that the above compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 4.9 parts by weight in terms of SiO ₂ .
Next, with respect to 105 parts by weight of the rubber composition, zinc oxide, stearic acid, powdered sulfur, and a vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Example 1, thereby blending rubber. Got. A vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.

Example 3
XSBR latex and NR latex were mixed such that each rubber component was 50:50 by weight to obtain a mixed latex. Subsequently, water glass was mix | blended with the obtained mixed latex, and the mixing | blending latex was obtained by stirring for 1 hour. The amount of water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the XSBR component.

Next, a thin sheet-like rubber composition (silicate XSBR / NR) was obtained in the same manner as in Example 1 except that the above-described compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 4.6 parts by weight in terms of SiO ₂ .
Next, with respect to 105 parts by weight of the rubber composition, zinc oxide, stearic acid, powdered sulfur, and a vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Example 1, thereby blending rubber. Got. A vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.

Example 4
The amide-modified SBR latex and the NR latex were mixed so that each rubber component was 50:50 by weight to obtain a mixed latex. Subsequently, water glass was mix | blended with the obtained mixed latex, and the mixing | blending latex was obtained by stirring for 1 hour. The blending amount of the water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ conversion amount) was 10 parts by weight with respect to 100 parts by weight of the amide-modified SBR component.

Next, a thin sheet rubber composition (silicic acid-amide modified XSBR / NR) was obtained in the same manner as in Example 1 except that the above compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 4.9 parts by weight in terms of SiO ₂ .
Next, with respect to 105 parts by weight of the rubber composition, zinc oxide, stearic acid, powdered sulfur, and a vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Example 1, thereby blending rubber. Got. A vulcanized rubber sheet having a thickness of 22 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.

Example 5
ENR latex and NR latex were mixed so that the respective rubber contents were 50:50 by weight to obtain a mixed latex. Subsequently, water glass was mix | blended with the obtained mixed latex, and the mixing | blending latex was obtained by stirring for 1 hour. The blending amount of the water glass was adjusted so that the amount of the silicic acid component produced from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the ENR component.

Next, a thin sheet rubber composition (silicic acid ENR / NR) was obtained in the same manner as in Example 1 except that the above-described compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 4.6 parts by weight in terms of SiO ₂ .
Next, with respect to 105 parts by weight of the rubber composition, zinc oxide, stearic acid, powdered sulfur, and a vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Example 1, thereby blending rubber. Got. A vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.

Example 6
Carboxylated PSBR latex and SBR latex were mixed so that the respective rubber contents were 50:50 by weight to obtain a mixed latex. Subsequently, water glass was mix | blended with the obtained mixed latex, and the mixing | blending latex was obtained by stirring for 1 hour. The blending amount of the water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the carboxylated PSBR content.

Next, a thin sheet rubber composition (silicic acid-carboxylated PSBR / SBR) was obtained in the same manner as in Example 1 except that the above compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 4.8 parts by weight in terms of SiO ₂ .
Next, with respect to 105 parts by weight of the rubber composition, zinc oxide, stearic acid, powdered sulfur, and a vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Example 1, thereby blending rubber. Got. A vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.

Example 7
Water glass was added to 100 parts by weight of rubber in the amino-modified XSBR latex and stirred for 1 hour. The blending amount of the water glass was adjusted so that the amount of the silicic acid component produced from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the amino-modified XSBR component. Further, an SBR latex was blended into the mixture thus obtained, and a blended latex was obtained by adjusting the blending ratio of the SBR component and the amino-modified SBR component to 70:30.

Next, the blended latex was further stirred for 30 minutes and slowly dropped into 2N-sulfuric acid, and the massive coagulum thus obtained was immersed in ion-exchanged water for a whole day and washed. The ion exchange water was changed several times. Further, after washing the coagulated product, it is molded into a thin sheet while being washed with a water squeeze roll, and dried in an oven at 40 ° C. to obtain a rubber composition (silicate-amino-modified XSBR / SBR). Obtained. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 2.9 parts by weight in terms of SiO ₂ .

  Next, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1.5 parts by weight of powdered sulfur, 1.0 part by weight of a vulcanization accelerator (CBS) and a vulcanization accelerator with respect to 103 parts by weight of the rubber composition. (D) Compounding rubber was obtained by blending 0.6 parts by weight and kneading with a kneader (mixing laboratory of the above-mentioned kneading test apparatus). A vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.

Example 8
Water glass was added to 100 parts by weight of rubber in the amide-modified SBR latex and stirred for 1 hour. The blending amount of the water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the amide-modified SBR component. Furthermore, a blended latex was obtained by blending the SBR latex into the mixture thus obtained and adjusting the blending ratio of the SBR component and the amide-modified SBR component to 70:30.

Next, the blended latex was further stirred for 30 minutes and slowly dropped into 2N-sulfuric acid, and the massive coagulum thus obtained was immersed in ion-exchanged water for a whole day and washed. The ion exchange water was changed several times. Further, after washing the coagulated product, it is molded into a thin sheet while being washed with a water squeeze roll, and dried in an oven at 40 ° C. to thereby obtain a rubber composition (silicate-amide-modified SBR / SBR). Obtained. The content of the silicic acid component (silica) in 100 parts by weight of the rubber composition was 3.0 parts by weight in terms of SiO ₂ .

Next, with respect to 103 parts by weight of the rubber composition, zinc oxide, stearic acid, powdered sulfur and a vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Example 8. Got rubber. A vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Example 1 except that this compounded rubber was used.
Comparative Example 1
With respect to 100 parts by weight of the rubber content in the carboxylated PSBR latex, water glass was blended and stirred for 1 hour to obtain a blended latex. The amount of water glass was adjusted so that the amount of silicic acid component produced from water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of carboxylated PSBR.

  Subsequently, the blended latex was slowly dropped into 2N-sulfuric acid, and the coagulated material thus obtained was immersed in ion-exchanged water for a whole day and washed. The ion exchange water was changed several times. Further, the coagulated product is formed into a thin sheet while being washed with a water squeeze roll, and dried in an oven at 40 ° C. to obtain an unvulcanized compounded rubber sheet (silicic acid-carboxylated PSBR). It was.

A part of the obtained unvulcanized compounded rubber sheet was put in a crucible, heated at 650 ° C. for 1 hour and incinerated, and then the amount of remaining ash was measured, whereby the silica in 100 parts by weight of the compounded rubber was measured. When the content of the acid component (silica) was calculated, it was 9.7 parts by weight in terms of SiO ₂ .
Separately from this, NR latex is slowly dropped into 2N-sulfuric acid, and the coagulated product thus obtained is washed, molded and dried in the same manner as described above to obtain an unvulcanized natural product. A rubber sheet was obtained.

  Next, 55 parts by weight of the unvulcanized blended rubber sheet (silicic acid-carboxylated PSBR) and 50 parts by weight of the unvulcanized natural rubber sheet were blended, and the resulting mixture was 105 parts by weight. , 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1.5 parts by weight of sulfur powder, 1.0 part by weight of vulcanization accelerator (CBS) and 0.6 part by weight of vulcanization accelerator (D) A compounded rubber (silicic acid-carboxylated PSBR + NR) was obtained by kneading with a kneading machine (kneading test apparatus Mix Lab, manufactured by Moriyama Co., Ltd.).

The compounded rubber was molded into a sheet shape and vulcanized at 170 ° C. with an electric press to obtain a vulcanized rubber sheet having a thickness of 2 mm. The vulcanization time was the time required to reach 90% of the maximum torque value (T ₉₀ ) as described above.
Comparative Example 2
With respect to 100 parts by weight of the rubber content in the amino-modified XSBR latex, water glass was blended and stirred for 1 hour to obtain a blended latex. The amount of water glass was adjusted so that the amount of silicic acid component generated from water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of amino-modified XSBR.

Next, an unvulcanized compounded rubber sheet (silicic acid-amino-modified XSBR) was obtained in the same manner as in Comparative Example 1 except that the compounded latex was used. The content of silicic acid component (silica) in 100 parts by weight of the unvulcanized compounded rubber sheet was 9.6 parts by weight in terms of SiO ₂ .
Next, 55 parts by weight of the above-mentioned unvulcanized compounded rubber sheet (silicate-amino-modified XSBR) and 50 parts by weight of the same unvulcanized natural rubber sheet prepared in Comparative Example 1 were obtained. By blending and kneading zinc oxide, stearic acid, powdered sulfur and vulcanization accelerator (CBS, D) under the same conditions as in Comparative Example 1 with respect to 105 parts by weight of the mixture, compounded rubber (silicic acid- Amino-modified XSBR + NR) was obtained. Further, a vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Comparative Example 1 except that this compounded rubber was used.

Comparative Example 3
Water glass was added to 100 parts by weight of rubber in the XSBR latex and stirred for 1 hour to obtain a compounded latex. The blending amount of the water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the XSBR component.

Next, an unvulcanized compounded rubber sheet (silicate XSBR) was obtained in the same manner as in Comparative Example 1 except that the compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of this unvulcanized compounded rubber sheet was 9.0 parts by weight in terms of SiO ₂ .
Next, 55 parts by weight of the above unvulcanized compounded rubber sheet (silicate XSBR) and 50 parts by weight of the same unvulcanized natural rubber sheet prepared in Comparative Example 1 were blended, and the resulting mixture 105 was obtained. Compounding rubber (silicate XSBR + NR) is obtained by blending and kneading zinc oxide, stearic acid, powdered sulfur and vulcanization accelerator (CBS, D) under the same conditions as in Comparative Example 1 with respect to parts by weight. It was. Further, a vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Comparative Example 1 except that this compounded rubber was used.

Comparative Example 4
With respect to 100 parts by weight of rubber in the amide-modified SBR latex, water glass was blended and stirred for 1 hour to obtain a blended latex. The blending amount of the water glass was adjusted so that the amount of the silicic acid component generated from the water glass (SiO ₂ conversion amount) was 10 parts by weight with respect to 100 parts by weight of the amide-modified SBR component.

Next, an unvulcanized compounded rubber sheet (silicic acid-amide modified SBR) was obtained in the same manner as in Comparative Example 1 except that the above compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the unvulcanized compounded rubber sheet was 9.5 parts by weight in terms of SiO ₂ .
Next, 55 parts by weight of the above-mentioned unvulcanized compounded rubber sheet (silicic acid-amide modified SBR) and 50 parts by weight of the same unvulcanized natural rubber sheet prepared in Comparative Example 1 were obtained. By blending and kneading zinc oxide, stearic acid, powdered sulfur and vulcanization accelerator (CBS, D) under the same conditions as in Comparative Example 1 with respect to 105 parts by weight of the mixture, compounded rubber (silicic acid- Amide-modified SBR + NR) was obtained. Further, a vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Comparative Example 1 except that this compounded rubber was used.

Comparative Example 5
With 100 parts by weight of rubber in the ENR latex, water glass was blended and stirred for 1 hour to obtain a blended latex. The blending amount of the water glass was adjusted so that the amount of the silicic acid component produced from the water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of the ENR component.

Next, an unvulcanized compounded rubber sheet (silicic acid ENR) was obtained in the same manner as in Comparative Example 1 except that the compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of this unvulcanized compounded rubber sheet was 9.0 parts by weight in terms of SiO ₂ .
Next, 55 parts by weight of the above-mentioned unvulcanized compounded rubber sheet (silicate ENR) and 50 parts by weight of the same unvulcanized natural rubber sheet produced in Comparative Example 1 were blended, and the resulting mixture 105 was obtained. Compounding rubber (silicic acid ENR + NR) is obtained by blending and kneading zinc oxide, stearic acid, powdered sulfur and vulcanization accelerator (CBS, D) under the same conditions as in Comparative Example 1 with respect to parts by weight. It was. Further, a vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Comparative Example 1 except that this compounded rubber was used.

Comparative Example 6
With respect to 100 parts by weight of the rubber content in the amino-modified XSBR latex, water glass was blended and stirred for 1 hour to obtain a blended latex. The amount of water glass was adjusted so that the amount of silicic acid component generated from water glass (SiO ₂ equivalent amount) was 10 parts by weight with respect to 100 parts by weight of amino-modified XSBR.

Next, an unvulcanized compounded rubber sheet (silicic acid-amino-modified XSBR) was obtained in the same manner as in Comparative Example 1 except that the compounded latex was used. The content of the silicic acid component (silica) in 100 parts by weight of the unvulcanized compounded rubber sheet was 9.8 parts by weight in terms of SiO ₂ .
On the other hand, carboxylated PSBR latex was slowly dropped into 2N-sulfuric acid, and the coagulated product thus obtained was washed, molded and dried in the same manner as described above to obtain an unvulcanized carboxylated PSBR sheet. Got.

  Next, 55 parts by weight of the unvulcanized compounded rubber sheet (silicic acid-amino-modified XSBR) and 50 parts by weight of the unvulcanized carboxylated PSBR sheet were blended, and 105 parts by weight of the resulting mixture was mixed. Then, under the same conditions as in Comparative Example 1, zinc oxide, stearic acid, powdered sulfur and vulcanization accelerator (CBS, D) were blended and kneaded to blend rubber (silicic acid-amino modified XSBR + carboxylated PSBR). Got. Further, a vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Comparative Example 1 except that this compounded rubber was used.

Comparative Example 7
The SBR latex was slowly dropped into 2N-sulfuric acid, and the coagulated product thus obtained was washed, molded and dried in the same manner as described above to obtain an unvulcanized SBR sheet.
Next, 55 parts by weight of the same unvulcanized compounded rubber sheet (silicic acid PSBR) produced in Comparative Example 1 and 50 parts by weight of the unvulcanized SBR sheet were blended, and 105 weight parts of the resulting mixture was obtained. To the part, zinc oxide, stearic acid, powdered sulfur and vulcanization accelerator (CBS, D) were blended and kneaded under the same conditions as in Comparative Example 1 to obtain a blended rubber (silicic acid PSBR + SBR). . Further, a vulcanized rubber sheet having a thickness of 2 mm was obtained in the same manner as in Comparative Example 1 except that this compounded rubber was used.

  Table 1 shows the compositions of the rubber composition and the compounded rubber in Examples 1 to 7. Moreover, the composition of the unvulcanized compounded rubber and compounded rubber in Comparative Examples 1 to 7 is shown in Tables 1 to 4.

<Evaluation of vulcanized rubber sheet>
The following physical properties were evaluated for the vulcanized rubber sheets obtained in each Example and Comparative Example.
(1) Mechanical strength Based on JIS K 6251 “Tensile test method for vulcanized rubber”, tensile stress M ₁₀₀ (MPa) at 100% elongation, tensile strength T _B (MPa), and elongation at break E _B (%) Was measured. For the measurement, a test piece (dumbbell No. 3 type) obtained by hollowing out a vulcanized rubber sheet was used, and the measurement conditions were a temperature of 23 ° C. and a tensile speed of 500 mm / min.

(2) Hardness The durometer hardness (type A) of the vulcanized rubber sheet was measured according to JIS K 6253 “Method for testing the hardness of vulcanized rubber and thermoplastic rubber”.
(3) Hysteresis loss After the test piece (dumbbell No. 3 type) obtained by punching out the vulcanized rubber sheet was stretched until the elongation reached 100%, the operation of returning to the original state was repeated three times, and the third tension- Based on the hysteresis loop in the restoration operation, the hysteresis loss (%) was calculated.

(4) Presence / absence of aggregates By cutting out a thin layer sheet having a thickness of about 0.05 mm from each vulcanized rubber sheet obtained in each Example and Comparative Example, and observing with an optical microscope (30 times) It was confirmed whether or not agglomerates of SiO ₂ were present in the rubber.
The above results are shown in Tables 5 and 6.

The vulcanized rubber sheets obtained in Example 1 and Comparative Example 1 were observed with a scanning probe microscope (SPM), so that the domain in the rubber (silicic acid component forming an island part of a sea-island structure). When the size (μm) of (silica) region was measured, it was 3 μm or less in Example 1, whereas a domain having a size exceeding 1 mm was observed in Comparative Example 1.
As is clear from Tables 5 and 6, the vulcanized rubber sheets molded using the rubber compositions obtained in Examples 1 to 9 were compared with the vulcanized rubber sheets obtained in Comparative Examples 1 to 7. High modulus and high hysteresis loss.

Claims (7)

A compounded latex containing rubber (A) and rubber (B) of different types and water glass is obtained by coagulating with an acid or salt,
The rubber (A) has at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group, an amino group, a carbamoyl group, an N-hydroxymethylcarbamoyl group and an epoxy group in the molecule, and ,
The rubber (B) is state, and are not to produce rubber (B) alone rubber capable kneading process when latex was coagulated by acid or salt in the coexistence of water glass,
The mixing ratio of the rubber (A) and the rubber (B) is 5: 95 to 97: 3 der Rukoto characterized, rubber composition.   The diene type in which the rubber (A) has at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group, an amino group, a carbamoyl group, an N-hydroxymethylcarbamoyl group and an epoxy group in the molecule The rubber composition according to claim 1, wherein the rubber composition is rubber.   The rubber composition according to claim 2, wherein the diene rubber is a copolymer of styrene and butadiene.   The rubber composition according to claim 1, wherein the rubber (A) is an epoxidized natural rubber.   The rubber (B) is a rubber which does not have any functional group of pyridyl group, carboxyl group, amino group, carbamoyl group, N-hydroxymethylcarbamoyl group and epoxy group in the molecule. The rubber composition according to any one of claims 1 to 4.   The rubber (B) has at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group, and an epoxy group in the molecule. The rubber composition as described. A latex of rubber (A) having at least one functional group selected from the group consisting of a pyridyl group, a carboxyl group, an amino group, a carbamoyl group, an N-hydroxymethylcarbamoyl group and an epoxy group in the molecule; The latex of the rubber (B), which is different from the rubber (A) and produces a rubber that can be kneaded when coagulated with an acid or salt in the presence of water glass, and water glass , After blending the rubber (A) and the rubber (B) so that the blending ratio is 5:95 to 97: 3 to prepare a blended latex, the resulting blended latex is coagulated with an acid or a salt. A process for producing a rubber composition, characterized by comprising: