Mixture containing sulfur-containing organosilicon compound and method for producing the same

The present invention relates to a mixture containing a sulfur-containing organic silicon compound as a main component and having excellent storage stability, and a method for producing the same.

Conventionally, a sulfur-containing organic silicon compound has been used as an adhesion aid between a filler and rubber (Patent Document 1). In the sulfur-containing organic silicon compound, the OH group and the alkoxy group on the surface of the filler react, and the rubber and the sulfur portion react to form a chemical bond between the filler and the rubber, and the mechanical characteristics of the rubber. To improve. Further, it is known that by reacting with the OH groups on the surface of the filler, the fillers are prevented from agglomerating with each other, the viscosity of the rubber composition is prevented from being remarkably increased, and the processability is significantly improved.

However, such sulfur-containing organic silicon compounds are often liquids, and the hydrolyzable groups contained in the compounds are easily condensed with polysiloxane in the presence of water and are easily modified (non-patented). Document 1), its handling is difficult. Therefore, such a sulfur-containing organic silicon compound is often supported on a solid and used as a mixture with the solid.

For example, as the existing mixture, a mixture using carbon black as a carrier (Patent Document 2) and an organosilicon mixture having silicic acid (Patent Document 3) are known, but the former is clear because the mixture is black. It cannot be used for colored rubber compositions, and the latter is not yet stable in storage and needs to be stored in a closed container. On the other hand, although a white mixture having excellent storage stability has been disclosed (Patent Document 4), there are drawbacks such as the need to use a special filler as a carrier.

<patcit num="1"><text>European Patent No. 501227</text></patcit><patcit num="2"><text>German Patent No. 2255577</text></patcit><patcit num="3"><text>WO97 / 07165</text></patcit><patcit num="4"><text>Japanese Patent Application Laid-Open No. 2002-20651</text></patcit><nplcit num="1"><text>Silane Coupling Agents, 2nd Edition, Edwin P. Plueddemann ed., Plenum Press</text></nplcit>

<p> An object of the present invention is to provide a mixture containing a sulfur-containing organic silicon compound as a main component, which does not require a special carrier as in the above prior art, has excellent storage stability, and exhibits a light color, and a method for producing the same. It is to be.</p>

<p> In view of the above problems, the present inventors have diligently studied a mixture of a sulfur-containing organic silicon compound and an inorganic filler having silicic acid, and as a result, have completed the following invention.</p><p> That is, in the present invention, after the sulfur-containing organic silicon compound (1) represented by the general formula [I] and the inorganic filler (2) having silicic acid are reacted in the presence of the weakly acidic compound (3). , Metal oxide (4) is added to neutralize, and then a new sulfur-containing organic silicon compound (1) is added to the reaction mixture. As long as it is essentially composed of these four components, it may contain some other optional components as long as it does not deviate from the gist of the present invention.</p><p><chemistry num="1"><img file="JP2005298435A_D0001.tif" /></chemistry>(In the formula, R¹Is a monovalent hydrocarbon group with 1 to 5 carbon atoms, R²Is a divalent hydrocarbon group with 1 to 9 carbon atoms, and x is an integer of 2 to 6. )</p>

<p> A versatile filler can be used to provide a light-colored, sulfur-containing organic silicon compound-based mixture with excellent storage stability. Since the mixture obtained by the present invention has the above-mentioned properties, it can be effectively used as an adhesion aid added to the rubber composition.</p>

The sulfur-containing organic silicon compound (1) is a sulfur-containing organic silicon compound represented by the general formula [I].<chemistry num="2"><img file="JP2005298435A_D0002.tif" /></chemistry>(In the formula, R¹Is a monovalent hydrocarbon group with 1 to 5 carbon atoms, R²Is a divalent hydrocarbon group with 1 to 9 carbon atoms, and x is an integer of 2 to 6. )

Specifically, Cabras 2A, Cabras 2B, Cabras 4 (above, manufactured by Daiso Co., Ltd.), Si75, Si69 (above, manufactured by Degussa), A-1289 (manufactured by Crompton), KBE-846 (Shin-Etsu Chemical (Shin-Etsu Chemical)) (Made by Co., Ltd.), but is not limited to these. In addition, these can be used alone or in combination. In particular, bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide are preferable.

As the inorganic filler (2) having silicic acid, wet silica, dry silica, aluminum silicate, mica, clay, zeolite and the like can be preferably used, and wet silica is particularly preferable.

Specific examples of wet silica include Tokseal U, Nipcil AQ (above, manufactured by Tokuyama Corporation), Carplex # 1120, Carplex # 67 (above, manufactured by Shionogi Corporation), Ultrasil VN- 3 (manufactured by Degusa), Zeosil 115GR, Zeosil 165GR, Zeosil 215GR (above, manufactured by Rodea), Hicil 233, Hicil 237, Hycil 255 (above, manufactured by PPG), etc. It's not a thing. High sill 233 is particularly preferable.

Inorganic filler (2) with silicic acid has a BET specific surface area of 50 to 350 m.²It is preferably / g, and it is preferably used after being sufficiently dried to remove adhering water.

The weakly acidic compound (3) is not particularly limited as long as it promotes the hydrolyzability of the sulfur-containing organic silicon compound (1), and for example, carboxylic acids such as stearic acid, lauric acid and benzoic acid, phenol and cresol. , Timor, t-butylphenol and other phenols can be preferably mentioned. Stearic acid is particularly preferable.

The metal oxide (4) is not particularly limited as long as it can receive the above-mentioned weakly acidic compound (3), and for example, metal oxides such as zinc oxide, magnesium oxide, and calcium oxide can be preferably mentioned. Zinc oxide is particularly preferable.

The role of the weakly acidic compound (3) and the metal oxide (4) is that the weakly acidic compound promotes the hydrolysis of the sulfur-containing organic silicon compound (1), and the surface silanol of the inorganic filler (2) having silicic acid. It is to promote the reaction with the group and to neutralize the weakly acidic compound after the reaction of the sulfur-containing organic silicon compound with the metal oxide and the inorganic filler having silicic acid.

The composition ratio of the mixture of the sulfur-containing organic silicon compound (1) and the silicic acid-containing inorganic filler (2) according to the present invention is that the sulfur-containing organic silicon compound (1): the silicic acid-containing inorganic filler (2) is by weight%. 30:70 to 70:30 is preferable, and 40:60 to 60:40 is more preferable.

The amount of the weakly acidic compound (3) added is preferably 0.01 to 5% by weight, more preferably 0.05 to 3% by weight, based on the inorganic filler (2) having silicic acid. On the other hand, the amount of the metal oxide (4) added is preferably equivalent to 3 times equivalent to that of the weakly acidic compound (3), and more preferably equivalent to 1.5 times equivalent.

Next, a preferable method for producing the mixture will be described. First, as a pretreatment of the inorganic filler (2) having silicic acid, it is preferable to sufficiently remove the adhering water. Specifically, the filler is heat-treated at 100 ° C. or higher, preferably 105 to 130 ° C. The heating may be performed under reduced pressure. The heating time depends on the heating temperature, the degree of decompression, etc., but for example, if the heating temperature is 105 ° C, it may be heated for 10 minutes or more, preferably 1 hour to 10 hours, more preferably about 3 hours.

The weakly acidic compound (3) is then added to the pretreated inorganic filler (2), if necessary. When the weakly acidic compound has sufficient heat resistance under the present drying conditions, it may coexist in advance during the pretreatment of the inorganic filler.

Further, a part of the sulfur-containing organic silicon compound (1) is added and mixed. The preferable amount of the sulfur-containing organic silicon compound added is 5 to 20% by weight, more preferably 10 to 15% by weight, based on the inorganic filler (2) having silicic acid. The mixing time depends on the temperature conditions, stirring conditions, etc., but is preferably about 10 minutes to 3 hours, more preferably 30 minutes to 2 hours.

Then, the metal oxide (4) is added, and the mixture is preferably mixed for 10 minutes to 2 hours, more preferably 30 minutes to 1 hour.

Finally, the remaining sulfur-containing organic silicon compound is further added, and the mixture is preferably mixed and stirred for 10 minutes to 2 hours, more preferably 30 minutes to 1 hour, and then cooled to obtain the mixture which is the object of the present invention. Obtainable.

The equipment that can be used for mixing is not particularly limited, and any mixer provided with a stirring blade and a heater may be used. For example, a super mixer, a Henschel mixer and the like can be mentioned.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

[Example 1a]

Put 33 g of Hysyl 233 (manufactured by PPG Co., Ltd.) and 0.1 g of stearic acid in a 500 mL four-necked flask equipped with a thermometer, agitator, nitrogen introduction tube, and distillation device, and put it in an oil bath at 120 ° C for 3 hours. The mixture was stirred to remove the adhering moisture. Next, 3.3 g of bis (3-triethoxysilylpropyl) tetrasulfide was added and mixed for 1.5 hours, 0.03 g of zinc oxide was added and mixed for 30 minutes, and then 30 g of bis (3-triethoxysilylpropyl) tetrasulfide was added. In addition, the mixture was mixed for 30 minutes, the oil bath was removed, and the mixture was allowed to cool to obtain a mixture.

[Example 2a]

The same procedure as in Example 1a was carried out except that the sulfur-containing organic silicon compound was replaced with bis (3-triethoxysilylpropyl) disulfide to obtain a mixture.

[Example 3a]

The same operation as in Example 1a was carried out except that the inorganic filler having silicic acid was replaced with Carplex # 1120 (manufactured by Shionogi Pharmaceutical Co., Ltd.) to obtain a mixture.

[Comparative example 1a]

The same operation as in Example 1a was carried out except that stearic acid and zinc oxide were not added, to obtain a mixture.

<u style="single">Evaluation test</u>(1) The mixtures obtained in the above Examples and Comparative Examples are added to predetermined styrene-butadiene rubber (SBR) and butadiene rubber (BR) to form a rubber compound, and the rubber physical characteristics are measured to measure each mixture. The properties were evaluated (in Table 2, the "Before Storage" column of Examples 1A, 2A, 3A, and Comparative Example 1A). (2) As a comparative test, instead of using a mixture, a considerable amount of pure bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide were added to prepare a rubber compound, and the same. An evaluation test was conducted (in Table 2, the "Before storage" column of Comparative Example 2 and Comparative Example 3). (3) Further, the mixture used in Examples 1A, 2A, 3A and Comparative Example 1A, and the pure bis (3-triethoxysilylpropyl) tetrasulfide, bis (3) used in Comparative Example 2 and Comparative Example 3. The characteristics of the -triethoxysilylpropyl) disulfide stored at 35 ° C. and 75% relative humidity under constant temperature and humidity for 3 weeks were similarly evaluated (in Table 2, all Examples and Comparative Examples " "After saving" column).

The composition (part by weight) is as follows.

<tables num="1"><img file="JP2005298435A_D0003.tif" /></tables>

In the above formulation, first knead the ingredients in part (i) for 20 minutes using a 7-inch roll adjusted to 40 ° C, then pass the roll at 100 ° C for 4 minutes, and then (ii). The components of the part were added and kneaded. Then, it was allowed to stand overnight, and the next day, 1.5 parts by weight of sulfur, 1.8 parts by weight of the accelerator N-cyclohexyl-2-benzothiazyl sulfenamide and 2 parts by weight of diphenylguanidine were kneaded.

The viscosity behavior (Table 2-1), vulcanizability (Table 2-2), and tensile properties (Table 2-3) of the obtained rubber compound were evaluated. Tensile characteristics conform to JIS-K6301.

<tables num="2"><img file="JP2005298435A_D0004.tif" /></tables>

As shown in Table 2-1 and Table 2-2, in Comparative Example 2 and Comparative Example 3, gelation occurs after storage and kneading itself cannot be performed before measurement. In addition, the viscosity of Comparative Example 1A also increased sharply after storage, suggesting the deactivation of the sulfur-containing organic silicon compound. The same can be said for the tensile properties, and as shown in Table 2-3, in Examples 1A to 3A, although a slight decrease in physical properties is observed after storage, a marked improvement is observed as compared with the comparative example.

As described above, it was possible to obtain a mixture of a sulfur-containing organic silicon compound having improved storage stability and an inorganic filler having silicic acid.

The mixture according to the present invention can be used as a necessary additive in various rubber products, for example, rubber industry products such as tires, belts and anti-vibration rubbers.