JP4595424B2 - Rubber composition for tire and method for producing the same - Google Patents

Description

  The present invention relates to a rubber composition for a tire containing a silica compound. More specifically, the present invention can efficiently disperse a large amount of silica without deteriorating productivity, and greatly increases tensile strength and wear resistance. The present invention relates to a rubber compound for a tire containing a silica compound and a method for producing the same.

  Generally, in a silica compound rubber, it is necessary to react a silane coupling agent and silica in a mixer, and in order to perform a sufficient reaction, it is necessary to lengthen the mixing time. By promoting this reaction, the dispersibility of silica is also improved. Further, it is known that lowering the rubber filling rate in the mixer is more effective for efficiently dispersing silica, but this is not preferable from the viewpoint of productivity. Therefore, there is a demand for a method for producing a rubber composition in which silica is efficiently dispersed in a short time without deteriorating productivity.

  Conventionally, as a prior art for efficiently dispersing silica in a rubber composition, 1) NBR and fine particle filler such as silica are mixed by dividing and mixing rubber components, and even with the same composition, higher viscoelastic temperature-frequency characteristics (Patent Document 1) for obtaining a rubber composition showing 2) A first crosslinkable unsaturated chain polymer is intimately mixed with carbon black at 130 to 180 ° C., followed by silica and a second crosslinkable A technique in which a saturated chain polymer is mixed and a reinforcing filler is homogeneously mixed in a matrix (Patent Document 2), and 3) In the first mixing step, a rubber component, silica and carbon black, a silane coupling agent, a poly The siloxane compound is mechanically mixed at 145 to 160 ° C. for 30 seconds to 5 minutes. Then, in the second mixing step, zinc white, stearic acid, wax, anti-aging agent and the like are added. A rubber composition for tires excellent in wet resistance and abrasion resistance, which is mixed at 0 to 160 ° C. for 30 seconds to 5 minutes, and in the third mixing step, sulfur and a vulcanization accelerator are mixed at a vulcanization temperature or lower. A technique (Patent Document 3) for obtaining the above is known.

JP 2003-335901 A JP 2000-119450 A JP 2002-220492 A

  In the present invention, conventional rubber kneading equipment can be used as it is, and silica can be dispersed in the rubber in a short time and efficiently without drastically changing the mixing conditions. It is an object of the present invention to provide a method for producing a silica-blended rubber composition masterbatch that greatly improves the properties of the product, and a tire rubber composition obtained thereby.

According to the present invention, in a two-stage mixing step method for producing a silica-containing rubber composition masterbatch in which a diene rubber, silica and other fillers, and other rubber drugs are mixed, In the mixer, 60 to 95 parts by weight of 100 parts by weight of the total amount of the predetermined diene rubber, 35 to 120 parts by weight of silica and other parts so that the master batch filling rate in the mixer is 45 to 65%. Composed of 0 to 50 parts by weight of a filler, 60 to 150 parts by weight in total of the silica and other fillers, 3 to 15% by weight of a sulfur-containing silane coupling agent relative to the amount of silica, and vulcanization Filled with other rubber agent excluding the agent, mixed at a temperature of 90 to 150 ° C. for 10 to 500 seconds, and then immediately and continuously as a second stage mixing, the remaining part of the diene rubber It was added, the production method of the rubber composition masterbatch comprises mixing 10 to 500 seconds under one hundred and five to one hundred and sixty-five ° C. is provided.

  Moreover, according to this invention, the rubber composition for tires formed by mix | blending vulcanizing compounding agents, such as sulfur and a vulcanization accelerator, with the said rubber composition masterbatch is provided.

According to the method for producing a rubber composition masterbatch according to the present invention, as a first stage mixing, in a closed mixer, a part of a predetermined amount of a predetermined rubber, a silica or other filler, a silane coupling agent, And other rubber chemicals are preliminarily mixed in a short time at a predetermined temperature, and then, as the second stage mixing, the remaining rubber is continuously fed into the mixture (without being discharged from the mixer). Furthermore, it has been found that by mixing for a short time at a predetermined temperature, a silica-blended rubber composition masterbatch having excellent properties with excellent dispersibility can be obtained without any significant loss in productivity and productivity. It is.

In the method for producing a rubber composition masterbatch according to the present invention, in the first stage mixing step, 60 to 95 parts by weight of a total amount of 100 parts by weight of a predetermined diene rubber is contained in a closed mixer such as Banbury or kneader. And 35 to 120 parts by weight of silica and 0 to 50 parts by weight of other fillers such as carbon black. The total amount of the silica and other fillers is 60 to 150 parts by weight, and 3 to 15% by weight based on the amount of silica. And a predetermined amount of other rubber agent excluding the vulcanizing compounding agent are added and mixed at a temperature of 90 to 150 ° C. for 10 to 500 seconds. Then, continuously, in the second stage mixing step, the remaining 40 to 5 parts by weight of the diene rubber is quickly charged from the inlet of the closed mixer, and subsequently 10 to 500 at a temperature of 105 to 165 ° C. The desired rubber composition masterbatch is obtained by mixing for 2 seconds and releasing the rubber masterbatch from the mixer after completion.

In the first mixing step of the present invention, when 60 to 95 parts by weight of the total amount of the predetermined diene rubber and a predetermined amount of silica or other filler are mixed in advance, unlike the conventional mixing method, the rubber Since the amount is reduced and mixed with a filler such as silica, as a result, the blending ratio of the filler is increased, and mixing can be performed while applying a high shearing force. Further, since the rubber content is small, mixing is inevitably performed at a low filling rate, and as a result, it is advantageous for efficiently dispersing silica, and the temperature rise during mixing can be kept low. And, in the second stage mixing step, because the remaining rubber is added and mixed, at the time of release, it becomes a normal rubber filling rate. As a result, the productivity of the rubber composition masterbatch is the same as before, Does not get worse.

Further, in the first stage mixing step of the present invention, the amount of the predetermined rubber component is set to 60 to 95 parts by weight out of 100 parts by weight of the total diene rubber compounding amount. This is because intimate mixing with fillers and other rubber drugs is possible, and if the blending amount of this rubber is less than 60 parts by weight of the predetermined diene rubber, the blending ratio of the filler becomes too high and the rubber It becomes hard and is not preferable because it is difficult to mix with the remaining rubber when it is added in the second stage, and when it exceeds 95 parts by weight, the effect of increasing the shearing force and the effect of decreasing the filling rate are insufficient. Therefore, it is not preferable. Furthermore, it is preferable to make the filling rate (volume ratio of the mixture to the void volume of the mixer) 45 to 65% when mixing in the first stage mixing step in order to make the dispersion effect better. .

  In addition, the amount of filler such as silica to be blended with the diene rubber in the first stage mixing step of the present invention is comprised of 35 to 120 parts by weight of silica and 0 to 50 parts by weight of carbon black and other fillers. The total amount of other fillers is 60 to 150 parts by weight. The reason why the blending amount of silica is 35 to 120 parts by weight is that, in the present invention, it is intended to obtain a particularly highly blended rubber composition of silica. If the amount of silica exceeds 120 parts by weight, it is difficult to uniformly disperse this even by the method of the present invention, which is not preferable. The blending ratio of silica with respect to the total amount of fillers such as silica is 50 to 100% by weight, preferably 55 to 95% by weight. When the blending ratio of silica is less than 50% by weight, a desired dispersion improving effect is observed, but it is not clear.

  Moreover, as mixing conditions in the first stage mixing step and the second stage mixing step of the present invention, in the same closed type mixer, in the first stage mixing step, at a temperature of 90 to 150 ° C., 10 to 500 In the second mixing step, it is necessary to mix for 10 to 500 seconds at a temperature of 105 to 165 ° C. Furthermore, the mixing operation in the first-stage mixing process and the second-stage mixing process is performed continuously, that is, when the first-stage mixing operation is completed, the mixer ram is raised and the remaining rubber is charged. However, it is necessary to immediately enter the second stage mixing operation. The order of addition of the diene rubber and filler in the first stage mixing step is not particularly limited, and a predetermined amount may be appropriately added. Prior to mixing, a stage for mixing only the diene rubber for 10 to 60 seconds may be provided in order to improve the incorporation of the compounding agent. As long as the predetermined blending amount is satisfied, a part of the filler and the blending agent may be added in the second stage mixing step.

  The rubber composition for tires of the present invention includes, for example, an open rubber composition masterbatch obtained by the first stage mixing and the second stage mixing and a vulcanizing compound such as sulfur and a vulcanization accelerator. It can be easily obtained by a conventional method such as further mixing using a roll or the like.

  Examples of the diene rubber in the present invention include natural rubber (NR), polyisoprene rubber (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), acrylonitrile-butadiene copolymer rubbers ( Diene synthetic rubbers such as NBR) and chloroprene rubber (CR) can be used alone or in combination of two or more thereof.

  Examples of the inorganic filler used in the present invention include inorganic powders such as clay, alumina, aluminum hydroxide, silicon carbide, calcium metasilicate, titanium dioxide, talc, and calcium carbonate in addition to various types of silica and carbon black. .

  Examples of the sulfur-containing silane coupling agent used in the present invention include 3-mercaptopropyltrimethoxysilane, bis- [3- (triethoxysilyl) -propyl] tetrasulfide, and 3-trimethoxysilylpropyl-N. , N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide and dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide .

  As other compounding agents such as rubber drugs used in the present invention, vulcanization or cross-linking agents, vulcanization or cross-linking accelerators, various oils, anti-aging agents, plasticizers and other tires, and other general rubbers are compounded. The compounding amount of the compounding agent such as a rubber drug can be a conventional general compounding amount as long as the object of the present invention is not violated.

  EXAMPLES Hereinafter, although this invention is further demonstrated by an Example and a comparative example, it cannot be overemphasized that the technical scope of this invention is not limited by these Examples.

Examples 1-2 and Comparative Examples 1-2
In Examples 1 and 2, the respective components in each example of the first stage mixing step shown in Table 1 below were put into a 1.7 L closed Banbury mixer and about 2 minutes 30 seconds until the temperature reached 150 ° C. The mixture was mixed and the ram was raised when the temperature reached 150 ° C. Immediately after that, the remaining rubber components were added in the second stage mixing, and further mixed for about 1 minute until the temperature reached 160 ° C. A vulcanization accelerator and sulfur shown in Table 1 were further added to the released masterbatch, and finally kneaded with an open roll for about 1.5 minutes to obtain a rubber composition. On the other hand, in Comparative Examples 1 and 2, in accordance with a conventional method, all of the components other than the crosslinking accelerator and sulfur shown in Table 1 below were put into a 1.7 L hermetic Banbury mixer at a time. Mix for ~ 5 minutes and release when 160 ° C is reached. A vulcanization accelerator and sulfur shown in Table 1 were further added to the released masterbatch, and finally kneaded with an open roll for about 1.5 minutes to obtain a rubber composition.

Test Samples The rubber compositions obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were respectively a 15 cm × 15 cm × 0.2 cm mold (tensile strength) and 16.5 cm × 6 cm × 0.5 cm. A test piece (rubber sheet) was produced by press vulcanization at a temperature of 160 ° C. for 30 minutes in a metal mold (filler dispersion, lamborn wear), and subjected to the following tests.

Test Method 1) Filler Dispersion TWA: Total White Area (TWA) value (%) was determined using a carbon dispersion measuring device disperser manufactured by Sweden Opti Grade. The smaller the numerical value, the smaller the number of poorly dispersed lumps and the better the dispersion.
2) Tensile strength: measured in accordance with JIS K 6251. The larger the value, the higher the strength and the better.
3) Lambourne abrasion resistance: Measured under the conditions of a load of 1.5 kg and a slip rate of 50% in accordance with JIS K 6264 using a lambourn wear tester. Example 1 or Example 2 was indexed as (Abrasion amount of Comparative Example 1 or 2) × 100 / (Abrasion amount of Example 1 or 2). The higher the index value, the better the wear resistance.

The results are shown in Table 1 below.

  In view of the results in Table 1 above, in the silica-blended rubber composition obtained by the two-stage mixing method of the present invention, the dispersibility of silica is extremely good as compared with the conventional method, and the tensile strength and It can be seen that the rubber properties are greatly improved in terms of wear resistance and the like.

  Therefore, the rubber composition obtained by the present invention is effective if it is used as a tire rubber composition.

Claims (3)

In a two-stage mixing step method for producing a silica-containing rubber composition masterbatch containing diene rubber, silica and other fillers, and other rubber drugs, the mixing is performed as a first-stage mixing in a closed mixer. 60 to 95 parts by weight of 100 parts by weight of the total amount of the predetermined diene rubber, 35 to 120 parts by weight of silica, and 0 to 50 parts by weight of other fillers so that the master batch filling rate in the machine is 45 to 65%. Other rubber drugs excluding 60 to 150 parts by weight of the total amount of the silica and other fillers, 3 to 15% by weight of the sulfur-containing silane coupling agent and the vulcanizing compound Then, the mixture is mixed for 10 to 500 seconds at a temperature of 90 to 150 ° C., and immediately thereafter, as the second stage mixing, the remaining amount of the diene rubber is added, and 10 Method for producing a rubber composition masterbatch comprises mixing 10 to 500 seconds under to 165 ° C..   A tire rubber composition comprising a rubber composition masterbatch obtained according to claim 1 and a vulcanizing compounding agent.   The rubber composition for a tire according to claim 2, wherein the rubber composition contains 50% by weight or more of silica based on the total amount of the silica and other fillers.