JP3363300B2 - Rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel rubber capable of producing a rubber product such as a fuel-efficient tire or a golf ball which requires a high balance of strength, low energy loss and high resilience. It relates to a composition.

[0002]

2. Description of the Related Art In the case of reinforcing a rubber product, rubber before vulcanization and a reinforcing material such as carbon black or silica (white carbon) are kneaded by using, for example, an internal mixer, and the shearing force is applied. It is common to knead a reinforcing material into rubber. In such a conventional reinforcing method (kneading method), it is known that the smaller the particle size of the reinforcing material particles is, the more the reinforcing effect is improved, and the strength of the rubber product after vulcanization is improved.

However, the smaller the particle size of the reinforcing material, the more difficult it is to knead into the rubber.
There was a limit to the reinforcing effect of rubber products. Further, in the above kneading method, the strength of the rubber product after vulcanization is improved as the amount of the reinforcing material added to the rubber is increased, but the loss coefficient tan δ is increased accordingly, and the low energy loss property of the rubber product is reduced. There is also a problem in that the so-called Pain effect, which reduces the resilience of the rubber product, increases with the decrease.

When silica is used as a reinforcing material, the addition of a small amount of a silane coupling agent can further improve the strength of the rubber product as compared with the case where the silane coupling agent is not added, and has a low energy loss property. It is known that this can be improved, but the effect is limited because the kneading method is basically used. Further, addition of the silane coupling agent may not prevent the reduction of the resilience of the rubber product, but may rather reduce the resilience.

Therefore, recently, as an alternative to the conventional kneading method for reinforcing a rubber product, an alkoxysilane compound has been used.
A method utilizing a sol-gel method for forming silica has been proposed. That is, at any stage of manufacturing a rubber product, when an alkoxysilane compound is added to the rubber, and this is hydrolyzed and then polycondensed, in the rubber product,
It was thought that the strength of the rubber product could be improved to a high level, which was difficult to achieve by the kneading method, because it was possible to generate and disperse fine silica particles having a minute particle diameter that were difficult to knead by the kneading method.

Therefore, various studies have been made in order to put into practical use a rubber reinforcing method utilizing the silica-forming reaction by the sol-gel method. For example, Teshima et al. Have proposed to incorporate a copolymer having a hydrophilic group into the rubber as a compatibilizer in order to smoothly introduce water necessary for the sol-gel reaction into the rubber (Kyushu. Research Report, Faculty of Engineering, Sangyo University, No. 29, p. 125).

Further, Yajima et al. Have conducted comparative studies on the function of various compounds (acids, bases, etc.) as a catalyst for the silica production reaction for the purpose of more efficient production of silica fine particles (6th session). Proceedings of the Elastomers Symposium, page 2).

[0008]

However, in spite of various investigations as described above, the method for reinforcing a rubber product using the silica-forming reaction by the sol-gel method is not always available at present. The current situation is that a satisfactory reinforcing effect is not obtained. The object of the present invention is to
It enables the practical application of a rubber composition capable of producing a rubber product that requires a high balance of strength, low energy loss and high resilience by a reinforcing method utilizing a silica formation reaction by a gel method. To provide the technology.

[0009]

In the conventional method for reinforcing a rubber product by the sol-gel method, the reason why a sufficient reinforcing effect cannot be obtained is that an alkoxysilane compound, water, or silica fine particles after generation are used as rubber. It is considered that the affinity for is not necessarily good. For example, sol
In the conventional reinforcing method by the gel method, generally, the rubber product after vulcanization is swollen with a suitable solvent capable of dissolving the alkoxysilane compound and water, and the alkoxysilane compound and water are contained in the rubber product. Is being done.

Therefore, the content of the alkoxysilane compound, and thus the content of the silica fine particles, is greatly influenced by the affinity between the alkoxysilane compound and the rubber constituting the rubber product, and its control is not easy. And especially in the case of a rubber product made of a rubber having an insufficient affinity with the alkoxysilane compound (as is the case with most rubbers), the content of the alkoxysilane compound cannot be increased so much as to obtain a sufficient reinforcing effect. Therefore, the reinforcing effect on the rubber product cannot be sufficiently obtained.

In order to control the content of the alkoxysilane compound, attempts have been made to adjust the degree of crosslinking of rubber products, devise a solvent, or devise a catalyst, but they are all satisfactory. It wasn't something going on. For example, the lower the crosslink density of a rubber product is, the more the swelling amount of the alkoxysilane compound is increased, and the higher the content of silica fine particles is. Therefore, it is considered that the crosslink density of the rubber product is lowered. When it is made to exist, there arises a problem that the physical properties of the rubber product itself are deteriorated.

When the affinity between the alkoxysilane compound and the rubber is not sufficient as described above, the alkoxysilane compound cannot be uniformly and stably contained in the rubber, so that the rubber product contains silica fine particles. There is also a phenomenon that a high concentration and a low concentration occur, or that the particle size of silica fine particles produced becomes large.

As a result, when the concentration of the silica fine particles varies, the low concentration hinders the improvement of the strength of the entire rubber product, and when the particle size of the silica fine particles becomes large, the above-mentioned small particles are used. The reinforcing effect due to the diameter reduction decreases, and in any case, the reinforcing effect on the rubber product cannot be sufficiently obtained. Furthermore, if the affinity of silica particles for rubber is not sufficient, the impact of peeling easily occurs at the interface between rubber and silica particles, and the reinforcing effect of silica particles cannot be fully exerted. It will not be effective enough.

Therefore, as a result of studies to improve the affinity between the rubber and the alkoxysilane compound, which is the cause of these problems, the inventors have found that when the silica fine particles are deposited by the sol-gel method, the rubber is The presence of a prescribed amount of silane coupling agent and / or a prescribed amount of carbon black solves the above-mentioned problems and provides a high balance of strength, low energy loss and high resilience. It has been found that a rubber composition capable of producing a rubber product required for is obtained.

Therefore, the rubber composition of the present invention comprises (1) 0.1 to 40 parts by weight of a silane coupling agent, and (2) 1 to 60 parts by weight of carbon black per 100 parts by weight of rubber. The general formula (1) contained in the rubber in the presence of at least one of the following:

[0016]

[Chemical 2]

[Wherein R ¹ , R ² , R ³ and R ⁴ are
The same or different monovalent organic groups are shown. However, R ¹ ,
At least one of R ² , R ³ and R ⁴ is an alkoxy group. ] The silica fine particles produced by the sol-gel method are dispersed from the alkoxysilane compound represented by the following formula.

Among the rubber compositions of the present invention having the above-mentioned constitution, those using a silane coupling agent are produced by the action of the silane coupling agent, that is, the alkoxysilane compound or water which is the raw material of the silica fine particles, or water. The affinity of silica particles for rubber molecules is improved,
As a result, the dispersibility of the silica fine particles in rubber and the affinity for rubber are improved.

The one using carbon black is
Various functional groups (for example, −
COOH, —OH, ═O, etc.) improves the affinity of the above-mentioned alkoxysilane compound, water, or generated silica fine particles for rubber molecules, and thus also improves the dispersibility of silica fine particles in rubber. . Further, in the case where the silane coupling agent and carbon black are used in combination, the dispersibility of the silica fine particles in the rubber and the affinity for the rubber are further improved by the synergistic effect of both.

Therefore, in the rubber composition of the present invention, fine silica particles having a fine and average particle size are uniformly dispersed in the rubber while maintaining a good affinity with the rubber. It becomes possible to manufacture a rubber product having both high strength and low energy loss property which could not be realized. Further, as a result of studies by the inventors, the rubber composition of the present invention can suppress the reduction of the resilience due to the Payne effect and maintain the high resilience of the rubber product even if the content of silica is increased. It became clear.

The main cause of the Pain effect is that when the rubber product is impacted, the higher order structure of the reinforcing material collapses. However, the rubber product comprising the rubber composition of the present invention has a unique structure in which fine silica particles having a fine and average particle size are uniformly dispersed in the rubber as described above, and it collapses due to impact. Since it has no higher-order structure,
The reduction of the resilience due to the Payne effect does not occur.

Therefore, according to the rubber composition of the present invention, a rubber product having high strength, low energy loss and high resilience can be obtained.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below. The rubber composition of the present invention, as in the prior art, swells a previously vulcanized rubber with an alkoxysilane compound, or a solvent that dissolves the alkoxysilane compound, and then adds water to form an alkoxysilane compound in the rubber. In addition to water, it is produced by producing silica fine particles by the sol-gel method, and a silane coupling agent, an alkoxysilane compound and water are mixed in a rubber solution or emulsion before vulcanization. Then, after generating silica fine particles by the sol-gel method, the rubber is vulcanized, or in a kneaded state by an internal mixer or the like, the silane coupling agent, the alkoxysilane compound, and water are added to the rubber before vulcanization. It is also possible to produce a composition by mixing the above, producing silica fine particles by the sol-gel method, and then vulcanizing the rubber. That.

In the above method, the silane coupling agent may be impregnated and added at the same time when the alkoxysilane compound or the like is added to the rubber after vulcanization, but the silane coupling agent acts more effectively on the rubber. To do so, it is preferable to add a silane coupling agent to the rubber before vulcanization and knead the vulcanized rubber. On the other hand, since carbon black is a solvent-insoluble solid and cannot be impregnated into the rubber after vulcanization, after addition to the rubber before vulcanization and kneading,
Rubber needs to be vulcanized.

Further, in the above method, by changing the swelling condition, the content of the silica fine particles is changed in the thickness direction of the rubber composition (not a natural variation but an intentional change). It is also possible to produce a rubber composition having physical properties such as strength inclined in the thickness direction, or a rubber composition having high strength only on the surface. As the rubber, various rubber materials can be used. For example, natural rubber (N
R), butadiene rubber (BR), isoprene rubber (I
R), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), fluorine rubber (FKM), butyl rubber (IIR), ethylene-propylene copolymer rubber (EPM), Ethylene-propylene-diene copolymer rubber (EPDM), silicone rubber, epichlorohydrin rubber (CO, ECO), polysulfide rubber (T), urethane rubber (U), styrene-butadiene-styrene block copolymer (SBS). , Styrene-isoprene-styrene block copolymer (SIS), 1,2-polybutadiene, trans polyisoprene and the like. These may be used alone or in combination of two or more.

The rubber can be vulcanized by various vulcanization systems depending on the type of the rubber, such as peroxide crosslinking, sulfur vulcanization, etc. For example, a cross-linking agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerating aid, a vulcanization retarder, etc. are added in the same proportions as in the past. Further, various additives such as various softening agents, plasticizers, processing aids, and anti-aging agents may be added to the rubber in the same proportion as in the past.

Examples of the silane coupling agent include mercaptosilanes, vinylsilanes, methacryloxysilanes, aminosilanes, glycidoxysilanes, tetrasulfide type silanes, and the like. The silane coupling agent to be used is appropriately selected in consideration of the type and vulcanization system. For example, mercaptosilanes, vinylsilanes, or methacryloxysilanes are suitable for peroxide-crosslinked rubber, and tetrasulfide-type silanes or mercaptosilanes are suitable for sulfur-vulcanized rubber. Is.

As described above, the amount of the silane coupling agent added is limited to 0.1 to 40 parts by weight with respect to 100 parts by weight of the rubber. If the amount of the silane coupling agent added is less than the above range, the effect of the addition cannot be obtained, and a rubber composition having high strength, low energy loss and high resilience cannot be obtained. On the contrary, even if the addition amount of the silane coupling agent exceeds the above range, further addition effect cannot be obtained, and the added silane coupling agent is not only wasted, but also such a large amount of silane coupling agent is used. Is difficult to uniformly knead with, for example, the rubber before vulcanization, and there is a possibility that a rubber composition cannot be produced.

The amount of silane coupling agent added is
Within the above range, it is particularly preferably 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight. Although various grades of carbon black can be used, rubber furnace blacks generally used for rubber, particularly SAF, ISAF, HAF, etc. are preferable.

As described above, the amount of carbon black added is limited to 1 to 60 parts by weight with respect to 100 parts by weight of rubber. If the amount of carbon black added is less than the above range,
The effect of addition cannot be obtained, and a rubber composition having high strength, low energy loss and high resilience cannot be obtained. On the other hand, when the amount of carbon black added exceeds the above range, the rubber before vulcanization becomes too hard and kneading becomes impossible, and the rubber composition cannot be produced.

The addition amount of carbon black is preferably 5 to 50 weight, especially within the above range. Examples of the alkoxysilane compound contained in the rubber together with water in the presence of the silane coupling agent and / or carbon black include the compounds represented by the general formula (1).

As described above, at least one of the groups R ^{1 to} R ⁴ in the general formula (1) may be an alkoxy group.
In order to obtain a dense and excellent reinforcing effect, the groups R ^{1 to} R ⁴
A tetraalkoxysilane compound in which each is an alkoxy group is more preferably used. Specific examples of such a tetraalkoxysilane compound include, but are not limited to, the following formula (1-1) in which each of the groups R ^{1 to} R ⁴ is an ethoxy group:

[0033]

[Chemical 3]

Tetraethoxysilane (hereinafter referred to as "TEOS") represented by the following formula is preferably used from the viewpoint of easy production and handling, reactivity with water, and the like. The content of the alkoxysilane compound in the rubber can be easily controlled by increasing or decreasing the addition amount of the silane coupling agent, which is different from the conventional case, particularly when the rubber composition is manufactured by the above-described manufacturing method.

That is, when the amount of the silane coupling agent added to the rubber is increased, the content of the alkoxysilane compound in the rubber is increased, and conversely, when the amount of the silane coupling agent added to the rubber is decreased, the alkoxysilane is increased. The content of the compound in the rubber is reduced. Therefore, the addition amount of the silane coupling agent may be increased or decreased within the above range in consideration of the content of the alkoxysilane compound in the rubber and the content of the silica fine particles.

The content of the silica fine particles may be set to an optimum value depending on the physical properties required for the rubber composition (particularly strength, energy loss property, repulsion property), which vary depending on the use of the rubber composition. . Water may be added in a small amount so as to start the hydrolysis reaction of the alkoxysilane compound.

In the present invention, a small amount of a basic catalyst such as butylamine, an acidic catalyst such as hydrochloric acid, or a tin compound such as dibutyltin dilaurate is added as a catalyst for promoting the hydrolysis reaction and condensation reaction of the alkoxysilane compound. You can also The particle size of the silica fine particles produced from the alkoxysilane compound by the sol-gel method is not particularly limited, but in order to obtain a rubber composition having high strength, low energy loss and high resilience, the particle size of the silica fine particles is Is preferably 120 Å or less. In order to keep the particle size of the silica fine particles within the above range, it is necessary to disperse the alkoxysilane compound in the rubber as uniformly as possible when carrying out the sol-gel reaction. For this reason, it is preferable to use, for example, (a) enhancing the affinity between the alkoxysilane compound and the rubber, (b) using as the rubber a rubber having a functional group capable of reacting with the alkoxy group of the alkoxysilane compound introduced therein. .

The particle size of the silica fine particles is preferably 10 to 100Å, and more preferably 20 to 8 even within the above range.
More preferably, it is 0Å.

[0039]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. << Adding Silane Coupling Agent-Peroxide Crosslinking System >> Example 1 Unvulcanized butadiene rubber [trade name B manufactured by Ube Industries, Ltd.
R-150L] 100 parts by weight, 1 part by weight of dicumyl peroxide [trade name of Park Mill D manufactured by NOF CORPORATION] as a cross-linking agent, and γ-mercaptopropyltrimethoxysilane [Shin-Etsu Chemical Co., Ltd.] as a silane coupling agent. 0.2 part by weight of KBM803 (trade name, manufactured by Co., Ltd.) is kneaded with an open roll to form a sheet having a thickness of 2 mm, and then 1
A rubber sheet was obtained by press vulcanization at 60 ° C. for 20 minutes.

Next, a sol containing 400 g of TEOS dissolved in 1.5 liter of tetrahydrofuran (THF).
After swelling 100 g of the above rubber sheet by swelling it in a gel reaction solution, 2.8 g of n-butylamine (catalyst) and a small amount of water were added and left at room temperature for 72 hours to carry out sol-gel reaction. Let it be done. Then, the rubber sheet was taken out from THF and left overnight to be dried, and then heated in an oven at 50 ° C. for 72 hours to complete the sol-gel reaction to obtain the rubber composition of Example 1. It was made. Examples 2 to 5 1 part by weight of γ-mercaptopropyltrimethoxysilane (Example 2), 2 parts by weight (Example 3), 3 parts by weight (Example 4), or 30 parts by weight (Example) A rubber sheet was obtained in the same manner as in Example 1 except that 5) was adopted.
Then, each rubber sheet was treated with the sol-gel reaction solution in the same manner as in Example 1 to prepare the rubber compositions of Examples 2-5. Comparative Example 1 Example 1 except that γ-mercaptopropyltrimethoxysilane, which is a silane coupling agent, was not added.
A rubber sheet was obtained in the same manner as in. Then, this rubber sheet was treated with a sol-gel reaction solution in the same manner as in Example 1 to prepare a rubber composition of Comparative Example 1. Comparative Example 2 When the compounding amount of γ-mercaptopropyltrimethoxysilane was set to 50 parts by weight, the roll processability was poor and kneading could not be performed, so the subsequent test was abandoned. Comparative Example 3 The rubber sheet obtained in Comparative Example 1 was not treated with the sol-gel reaction solution, and Comparative Example 3 was obtained. Comparative Examples 4 to 6 The rubber sheets obtained in Examples 2, 3 and 4 were not treated with the sol-gel reaction solution, but Comparative Example 4 (← rubber sheet of Example 2) and Comparative Example 5 (← of Example 3). Rubber sheet) and Comparative Example 6 (← rubber sheet of Example 4). Comparative Example 7 Unvulcanized butadiene rubber [trade name BR-150 described above
L] 100 parts by weight, 1 part by weight of a cross-linking agent dicumyl peroxide [Parkmill D, trade name above], and silane coupling agent γ-mercaptopropyltrimethoxysilane [trade name KBM803 above] 1 After 10 parts by weight and 10 parts by weight of silica particles for reinforcing material [average particle size 160Å, Nipseal VN3 manufactured by Nippon Silica Co., Ltd.] were kneaded with an open roll to form a sheet having a thickness of 2 mm, Press vulcanization was performed at 160 ° C. for 20 minutes to prepare a rubber composition of Comparative Example 7. Comparative Example 8 A rubber composition of Comparative Example 8 was prepared in the same manner as Comparative Example 7 except that the amount of γ-mercaptopropyltrimethoxysilane was 2 parts by weight and the amount of silica particles was 20 parts by weight. . Comparative Example 9 A rubber composition of Comparative Example 9 was produced in the same manner as Comparative Example 7 except that γ-mercaptopropyltrimethoxysilane was not compounded and the compounding amount of silica particles was 20 parts by weight.

Each of the above Examples and Comparative Examples (excluding Comparative Example 2)
The following tests were carried out to evaluate the characteristics. Silica Content Measurement The silica content [phr] of the rubber compositions of Examples and Comparative Examples was determined from the ash content obtained when thermogravimetric analysis was performed on the rubber compositions of Examples and Comparative Examples. Tensile Strength Test The stress M at 25% elongation of the rubber compositions of Examples and Comparative Examples
₂₅ , JIS K 6301 "vulcanized rubber physical test method"
It was measured according to the tensile test method described. The tensile speed was 500 mm / min. Measurement of Loss Coefficient, Shear Elastic Modulus The loss coefficient tan δ and the shear elastic modulus G ′ of the rubber compositions of Examples and Comparative Examples were measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho. The measurement conditions are 25 ° C and 10
Hz and shear strain rate ± 0.5%. Silica Particle Size Measurement Regarding the rubber compositions of Example 4, Comparative Example 1 and Comparative Example 8 among Examples and Comparative Examples, transmission electron microscope photographs (magnification: about 20,000 to 40,000 times) were taken, and the photographs were taken. Magnification from 80,000
Arbitrary silica particles 2 in the photograph, magnified 280,000 times
The diameter of 0 pieces was measured with a caliper. Then, the actual particle size was calculated from the average value of the measured values.

The above results are shown in Tables 1 to 3. Also,
For Comparative Example 1 and Examples 1 to 4 (all are sol-gel methods), and Comparative Examples 3, 7, and 8 (Comparative Examples 7 and 8 are kneading methods), the silica contents in Tables 1 to 3 above, respectively. And tensile strength M ₂₅ are shown in FIG. 1, silica content and shear modulus G ′ are shown in FIG. 2, and loss coefficient tan δ is shown in FIG.
Are plotted respectively.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

As shown in these tables and figures, in both the kneading method and the sol-gel method, the tensile strength M ₂₅ and the shear modulus G'increase as the silica content increases. , And the loss coefficient tan δ
The loss factor ta increases in the sol-gel method.
It was possible to suppress nδ to a substantially constant low level regardless of the silica content.

In addition, as a representative of the sol-gel method, Example 4 was used.
And a transmission electron micrograph of Comparative Example 1 (both magnification 40,000 times) and a transmission electron microscope photograph of the rubber composition of Comparative Example 8 (magnification 80,000 times) as a representative of the kneading method. In the rubber composition, as shown in FIG. 6, a higher-order structure of silica particles (collection of black dots in the figure) peculiar to the kneading method was observed, but the rubber compositions of Example 4 and Comparative Example 1 were As shown in FIGS. 4 and 5, it was observed that the silica fine particles having a fine particle size and a uniform particle size (black dots in the figures) were dispersed almost uniformly.

Further, the rubber composition of Example 4 shown in FIG.
Comparing with the rubber composition of Comparative Example 1 shown in FIG. 5, the former using the silane coupling agent has a larger number of silica fine particles having a finer particle size than the latter not using the silane coupling agent. It was found that it constitutes a dense dispersion structure. << Adding Silane Coupling Agent-Sulfur Vulcanization System >> Example 6 Unvulcanized Styrene Butadiene Rubber [Nippon Synthetic Rubber Co., Ltd.]
Manufactured by Ouchi Shinko Chemical Co., Ltd., 0.64 parts by weight, and vulcanization accelerator 1.2 parts by weight of sulfur which is a vulcanizing agent. When,
5 parts by weight of zinc white as a vulcanization accelerator and 1 part by weight of stearic acid, and 3 parts by weight of bis (3-triethoxysilylpropyl) tetrasulfide [trade name Si69 manufactured by Degussa Co.] as a silane coupling agent. Was kneaded with an open roll to form a sheet having a thickness of 2 mm, and then 160
A rubber sheet was obtained by press vulcanization at 60 ° C. for 60 minutes.

Then, this rubber sheet was treated with a sol-gel reaction solution in the same manner as in Example 1 to prepare a rubber composition of Example 6. Examples 7-9 The compounding amount of bis (3-triethoxysilylpropyl) tetrasulfide was 10 parts by weight (Example 7), 30 parts by weight (Example 8), or 40 parts by weight (Example 9). A rubber sheet was obtained in the same manner as in Example 6 except for the above. Then, each rubber sheet was treated with the sol-gel reaction solution in the same manner as in Example 1 to prepare the rubber compositions of Examples 7 to 9. Comparative Example 10 A rubber sheet was obtained in the same manner as in Example 6 except that bis (3-triethoxysilylpropyl) tetrasulfide was not added. Then, this rubber sheet was treated with a sol-gel reaction solution in the same manner as in Example 1, and Comparative Example 1
A rubber composition of 0 was prepared.

With respect to each of the above-mentioned Examples and Comparative Examples, each test of the above-mentioned silica content measurement, loss coefficient, and shear elastic modulus measurement was conducted to evaluate the characteristics. The results are shown in Table 4.

[0051]

[Table 4]

As shown in Table 4 above, also in the sulfur vulcanization system, the loss factor tan δ is the same as in the above peroxide crosslinking system.
Could be suppressed to an almost constant low level. << Carbon Black Addition-Sulfur Vulcanization System >> Example 10 Unvulcanized Styrene Butadiene Rubber [Product Name SL-
574] 100 parts by weight and vulcanization acceleration aid zinc white 5
Parts by weight and 1 part by weight of stearic acid, carbon black ISAF [trade name N220 manufactured by Mitsubishi Kasei Co., nitrogen adsorption specific surface area 115 m ² / g, DBP oil absorption 114 ml
/ 100 g ] 5 parts by weight with a test Banbury mixer, and then 1.2 parts by weight of sulfur which is a vulcanizing agent and 0.64 parts by weight of a vulcanization accelerator [trade name of NOXCELLER CZ mentioned above]. After adding and kneading with an open roll to form a sheet having a thickness of 2 mm, it was press-vulcanized at 160 ° C. for 60 minutes to obtain a rubber sheet.

Then, this rubber sheet was treated with a sol-gel reaction solution in the same manner as in Example 1 to prepare a rubber composition of Example 10. Examples 11 and 12 Carbon black was added in an amount of 20 parts by weight (Example 1).
A rubber sheet was obtained in the same manner as in Example 10 except that 1) or 50 parts by weight (Example 12) was used. Then, each rubber sheet was treated with the sol-gel reaction solution in the same manner as in Example 1 to prepare the rubber compositions of Examples 11 and 12. Comparative Example 11 When the compounding amount of carbon black was set to 70 parts by weight, it was too hard to knead, so the subsequent test was abandoned. Comparative Example 12 Unvulcanized styrene-butadiene rubber [trade name SL-
574] 100 parts by weight and vulcanization acceleration aid zinc white 5
By weight, 1 part by weight of stearic acid and 25 parts by weight of silica particles for reinforcing material [average particle size 160., Nipseal VN3, trade name mentioned above] were kneaded with a Banbury mixer for testing, and then a vulcanizing agent. 1.2 parts by weight of sulfur and 0.64 parts by weight of a vulcanization accelerator [trade name of NOXCELLER CZ mentioned above] were added, and the mixture was kneaded with an open roll to form a sheet having a thickness of 2 mm, and then 160 ° C. By press vulcanization for 60 minutes to prepare a rubber composition of Comparative Example 12. Comparative Example 13 Carbon black ISAF [trade name N220 mentioned above, nitrogen adsorption specific surface area 115 m ² / g, DBP oil absorption 114 m
The rubber composition of Comparative Example 13 was produced in the same manner as in Comparative Example 12 except that 20 parts by weight of 1/100 g ].

With respect to each of the above Examples and Comparative Examples (excluding Comparative Example 11), the respective tests of the above-mentioned silica content measurement, loss coefficient and shear elastic modulus measurement were carried out, and the characteristics thereof were evaluated. The above results are shown in Table 5 together with the results of Comparative Example 10.

[0055]

[Table 5]

As shown in Table 5, even in the carbon black-added system, the loss coefficient tan δ increases with the silica content in the kneading method, whereas the loss coefficient tan δ becomes the silica content in the sol-gel method. Regardless, I was able to keep it at a fairly low level. << Silane Coupling Agent-Carbon Black Combined-Sulfur Vulcanizing System >> Example 13 Unvulcanized Styrene Butadiene Rubber [Product Name SL-
574] 100 parts by weight and vulcanization acceleration aid zinc white 5
Parts by weight and 1 part by weight of stearic acid, and bis (3-triethoxysilylpropyl) which is a silane coupling agent.
10 parts by weight of tetrasulfide [trade name Si69 mentioned above] and carbon black ISAF [trade name N22 mentioned above]
0, nitrogen adsorption specific surface area 115 m ² / g, DBP oil absorption 1
14 ml / 100 g ] 20 parts by weight are kneaded in a test Banbury mixer, and then 1.2 parts by weight of sulfur which is a vulcanizing agent and a vulcanization accelerator [Nocceller CZ, trade name mentioned above].
0.64 parts by weight was added, and the mixture was kneaded with an open roll to form a sheet having a thickness of 2 mm, and then press-vulcanized at 160 ° C. for 60 minutes to obtain a rubber sheet.

Then, this rubber sheet was treated with a sol-gel reaction solution in the same manner as in Example 1 to prepare a rubber composition of Example 13. Comparative Example 14 Carbon black ISAF [trade name N220 mentioned above, nitrogen adsorption specific surface area 115 m ² / g, DBP oil absorption 114 m
1/100 g ] 20 parts by weight and 5 parts by weight of bis (3-triethoxysilylpropyl) tetrasulfide [trade name Si69 mentioned above] which is a silane coupling agent, were added in the same manner as in Comparative Example 12. Thus, a rubber composition of Comparative Example 14 was produced.

With respect to the above Examples and Comparative Examples, the respective tests of the above-mentioned silica content measurement, loss coefficient and shear elastic modulus measurement were conducted, and the characteristics thereof were evaluated. Further, with respect to the rubber composition of Example 13, a transmission electron micrograph (magnification: 12.5)
10,000 times), and enlarge the picture to 500,000 times,
The diameter of 20 arbitrary silica particles shown in the photograph was measured with a caliper. Then, the actual particle size was calculated from the average value of the measured values.

Table 6 shows the above results.

[0060]

[Table 6]

As shown in Table 6 above, even in the combined use system of silane coupling agent and carbon black, the sol-gel method could suppress the loss coefficient tan δ to a level lower than that of the kneading method. Further, when a transmission electron micrograph (magnification of 125,000) of the rubber composition of Example 13 is seen, as shown in FIG. 7, silica fine particles having a fine particle size and a uniform particle size (in the figure, It was observed that the black dots) were dispersed almost uniformly.

[0062]

As described above in detail, the rubber composition of the present invention has silica fine particles dispersed in a base rubber by a sol-gel method in the presence of a silane coupling agent and / or carbon black. Therefore, it has high strength, low energy loss, and high resilience. Therefore, the rubber composition of the present invention can be widely used in rubber products such as rubber materials for fuel-efficient tires and materials for golf balls, which require a high balance of strength, low energy loss and high resilience. Has a unique effect.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the content of silica in a rubber composition produced by a sol-gel method or a kneading method and the tensile strength M ₂₅ .

FIG. 2 is a graph showing the relationship between the content of silica in the rubber composition produced by the sol-gel method or the kneading method and the shear elastic modulus G ′.

FIG. 3 is a graph showing the relationship between the content of silica in the rubber composition produced by the sol-gel method or the kneading method and the loss coefficient tan δ.

4 is a transmission electron micrograph showing the particle structure of silica in the rubber composition of Example 4. FIG.

5 is a transmission electron micrograph showing the particle structure of silica in the rubber composition of Comparative Example 1. FIG.

6 is a transmission electron micrograph showing the particle structure of silica in the rubber composition of Comparative Example 8. FIG.

7 is a transmission electron micrograph showing the particle structure of silica in the rubber composition of Example 13. FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identifier FI C08K 5/541 C08K 5/54 (72) Inventor Katsumi Terakawa 2-14-24 Miyashita, Nishi-ku, Kobe-shi, Hyogo (72) Inventor Yoshiaki Miyamoto 1-32703 Migatadai, Nishi-ku, Kobe-shi, Hyogo (72) Inventor Nobu Sugitani 294-20 Shinosaka, Sakurai-shi, Nara (72) Inventor Seiji Banno 1-Kanoko-Taipei, Kita-ku, Kobe-shi, Hyogo 4-13 (56) Reference JP-A-7-33910 (JP, A) JP-A-5-125191 (JP, A) JP-A-5-271549 (JP, A) JP-A-6-136321 (JP, A) JP-A-8-319362 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 21/00 C08J 3/24 CEQ C08K 3/04 C08K 3/36 C08K 5/541

Claims (4)

(57) [Claims] 1. The amount of (1) 0.1 to 100 parts by weight of rubber.
40 parts by weight of silane coupling agent, and (2) 1-6
In the presence of at least one of 0 parts by weight of carbon black, the compound represented by the general formula (1): [In the formula, R ¹ , R ² , R ³ and R ⁴ represent the same or different monovalent organic groups. However, at least one of R ¹ , R ² , R ³ and R ⁴ is an alkoxy group. ] From the alkoxysilane compound represented by
A rubber composition, wherein silica fine particles produced by a gel method are dispersed. 2. The rubber composition according to claim 1, wherein the silica fine particles dispersed in the rubber have an average particle diameter of 120 Å or less. 3. A peroxide-crosslinked product according to claim 1 or 2.
The rubber composition described. 4. The rubber composition according to claim 1, which is sulfur vulcanized.