JP2009197065A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a more inexpensive rubber composition capable of obtaining high performance, in particular, high breaking characteristic by improvement of a softening agent component as compared with conventional. <P>SOLUTION: In the rubber composition, a mixture of asphalt and a vulcanized rubber powder is formulated relative to a diene based rubber, and the asphalt is a naphthene based asphalt. The mixture of the asphalt and the vulcanized rubber powder can be prepared by mixing/stirring them at 120°C or higher for 1 hour or longer. As the vulcanized rubber powder, the one obtained from a used rubber product, in particular, a waste tire can be preferably used. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition, and more particularly, to a rubber composition according to an improvement of a softener component.

  In rubber compositions generally used for tires and industrial articles, diene rubber compositions using natural rubber (NR), styrene-butadiene copolymer rubber (SBR) or the like as the rubber component are used as the polymer component. ing. For the purpose of ensuring the fracture characteristics and wear characteristics of the rubber composition, the rubber filler is usually blended at about 20 to 200 parts by mass with respect to 100 parts by mass of the polymer component.

  Furthermore, for the purpose of ensuring sufficient wear resistance in the rubber composition and reducing the cost, an oil component may be blended in an amount of about 5 to 150 parts by mass as a softening agent with respect to 100 parts by mass of the polymer component. Among the commercially available SBRs, there are many grades in which such an oil component is extended, and it is generally used as an excellent rubber in terms of a balance between cost, fracture characteristics and durability.

  However, in response to the general increase in the price of raw materials in recent years, there is a demand for cheaper and higher performance materials. Many technical developments such as improvement of the polymer component and improvement of the filler have been made for the rubber composition in response to such a practical requirement, but the improvement regarding the softening agent component has not been sufficiently performed.

  Conventionally, mineral oil-based materials have been used as rubber softeners from the viewpoints of high affinity with rubber used, low cost and high availability. Aromatic oil-based compositions are most frequently used in compounding compositions used for tire applications, and other high-boiling oils such as naphthenic and paraffinic oils are also widely used. . These high boiling oils are obtained by treating heavy oil components obtained in petroleum refining under certain hydrogenation conditions. Therefore, assuming that the price of petroleum products in recent years has risen, the use of these heavy oil components as C heavy oil is more important than softeners, so ensuring sufficient supply of these oils is an issue. It is coming.

Under such circumstances, development of asphalt as a new softener component has been actively carried out (for example, Patent Documents 1 to 3). For example, blown asphalt itself is a previously known material. In addition, naphthenic asphalt obtained from naphthenic crude oil, not aroma-based crude oil that has been widely used so far, has been used because of its good affinity for polymers.
Japanese Patent Laid-Open No. 11-302459 (Claims etc.) JP 2003-2143040 A (Claims etc.) JP 2001-2831 A (Claims etc.)

  However, aroma-based asphalt does not have a good affinity with polymers generally used in diene rubber compositions, and has problems with respect to fracture characteristics and durability. Therefore, conventional asphalt is not sufficient, and realization of a new softening agent component has been demanded as an inexpensive and high-performance material.

  Accordingly, an object of the present invention is to provide a rubber composition that is less expensive than the prior art and has improved performance, particularly high fracture characteristics, by improving the softener component.

  As a result of diligent investigations focusing on such a softener component for rubber, the present inventors considered that the above problems could be solved by modifying the asphalt itself. The modification by premixing molecular components was studied. Surprisingly, the rubber composition once compounded and vulcanized is further pulverized to a certain particle size or less, and the rubber powder is mixed with asphalt to obtain a material having insufficient rubber affinity such as asphalt. It has been found that a decrease in physical properties of the rubber composition when used as a softening agent can be minimized.

  In general, in the relationship between the softening agent component having a high affinity and the polymer component, sufficient entanglement is established, so that the softening agent component is sufficiently in a rubber composition formation as if it were a low molecular component of the polymer. Because it is captured, entanglement is established. On the other hand, in the case of using a softener component that does not have sufficient affinity such as asphalt, the entanglement between the softener component and the polymer main chain is not established at the molecular level, so that sufficient entanglement does not occur, Since the microparticles in the rubber not having such an entanglement act as a breakage starting point, it is considered that it is difficult to develop sufficient durability.

  On the other hand, asphalt mixed rubber composition prepared by mixing vulcanized rubber powder in asphalt to contain crosslinked rubber swelling particles, when an asphalt layer having such a microphase separation structure is generated However, it is considered that sufficient durability can be expected since it does not become a break point because it exhibits sufficient single stress retention.

  Furthermore, the present inventors conducted various studies focusing on the affinity with this asphalt component in order to improve performance. When naphthenic asphalt was used as the asphalt component, particularly excellent formulation properties Found that appears.

  That is, the rubber composition of the present invention is characterized in that a mixture of asphalt and vulcanized rubber powder is blended with diene rubber, and the asphalt is naphthenic asphalt.

  In the present invention, the mixture of asphalt and vulcanized rubber powder is preferably prepared by mixing and stirring at 120 ° C. or more for 1 hour or more. The vulcanized rubber powder is preferably obtained from a used rubber product, and more preferably obtained from a waste tire. Furthermore, in the rubber composition of this invention, it is preferable that 20-150 mass parts of rubber fillers are mix | blended with respect to 100 mass parts of said diene rubbers.

  According to the present invention, the configuration described above makes it possible to realize a rubber composition that is less expensive than the prior art and that provides high performance, particularly high fracture characteristics.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The rubber composition of the present invention is a mixture of a diene rubber and a mixture of asphalt and vulcanized rubber powder. Thereby, it is possible to obtain an inexpensive rubber composition by using asphalt, which is less expensive than the conventional softener component, and it is possible to highly secure the fracture characteristics of the rubber composition.

  In the present invention, it is necessary to use naphthenic asphalt obtained from naphthenic crude oil as asphalt. Thereby, as described above, a rubber composition having better performance can be obtained.

  The mixture of asphalt and vulcanized rubber powder used in the present invention is obtained by mixing vulcanized rubber powder in asphalt. The usable asphalt is not particularly limited as long as it is naphthenic asphalt derived from naphthenic crude oil. For example, straight asphalt 40/60, 60/80, 80/100, 100/120, etc. Can be mentioned. All of these can be easily obtained as commercial products, and can be used alone or in combination of two or more. The straight asphalt may be decolorized asphalt.

  Further, as the vulcanized rubber powder, it is preferable to use fine rubber powder having an average particle diameter in the range of 10 to 5000 μm. The material of the vulcanized rubber powder is not particularly limited, and any sulfur-crosslinked rubber having a general diene rubber such as NR, SBR, butadiene rubber (BR), or isoprene rubber (IR) as a polymer component may be used. Can also be used. Specifically, for example, used waste materials such as rubber tires, weather strips, hoses, etc., unnecessary end materials generated at the time of molding, crushed rubber powder obtained from molding defects, etc. can be suitably used. That is, in the present invention, the vulcanized rubber powder can be easily obtained from used rubber products such as waste tires, so that sufficient significance can be ensured in the implementation.

  The amount of vulcanized rubber powder in the mixture of asphalt and vulcanized rubber powder used in the present invention is usually 5 to 50 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of asphalt. When the amount of the vulcanized rubber powder is larger than this range, sufficient mixing and stirring may be difficult. When the amount is less than this range, the desired performance may not be sufficiently observed.

  The preparation method of the asphalt and vulcanized rubber powder used in the present invention is not limited as long as a sufficiently mixed state can be obtained. In particular, those obtained by dissolving vulcanized rubber powder in asphalt melted at high temperature exhibit good performance. Therefore, specifically, for example, vulcanized rubber powder is mixed with asphalt melted at 120 ° C. or higher, preferably 150 ° C. to 180 ° C., and the dissolution of the contents is confirmed using a propeller-compatible stirrer. The mixture can be prepared by stirring, and a good mixture can be obtained particularly when the mixture is stirred for 1 hour or longer, preferably 2 hours to 5 hours.

  There is no restriction | limiting in particular as diene type rubber | gum used for this invention, NR, SBR, BR, etc. can be used conveniently. Among them, SBR is particularly preferable, and those having a high styrene content with a styrene content of 30% by weight or more, particularly 30 to 100%, can be more suitably used. The blending amount of the asphalt and vulcanized rubber powder with respect to the diene rubber can be the same as that of a normal softener component, for example, 10 to 70 parts by mass with respect to 100 parts by mass of the diene rubber. It is.

  In the rubber composition of the present invention, various additives and rubber chemicals usually used in the rubber industry can be blended in addition to the diene rubber and the mixture of asphalt and vulcanized rubber powder.

  For example, carbon black or silica as a reinforcing material is preferably blended as a rubber filler. Examples of carbon black include grades such as GPF, FEF, SRF, HAF, ISAF, and SAF. Examples of silica include wet silica, dry silica, and colloidal silica. The amount of the filler for rubber can be 20 to 150 parts by mass with respect to 100 parts by mass of the diene rubber.

  Examples of the vulcanizing agent include sulfur and sulfur-containing compounds. The compounding quantity can be made into the range normally mix | blended with a rubber composition, for example, 0.1-10 mass parts as a sulfur content with respect to 100 mass parts of rubber components, Preferably it is 1-5 mass parts It is.

  Examples of the vulcanization accelerator include 1,3-diphenylguanidine, dibenzothiazyl disulfide, Nt-butyl-2-benzothiazylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide. , N, N′-dicyclohexyl-2-benzothiazolylsulfenamide, 2-mercaptobenzothiazole and the like. The blending amount of the vulcanization accelerator can also be within the range usually blended in the rubber composition, for example, 0.1 to 7 parts by weight, preferably 1 to 5 parts per 100 parts by weight of the rubber component. Part by mass.

  Other compounding agents commonly used in the rubber industry include, for example, anti-aging agents, zinc oxide, stearic acid, ozone degradation inhibitors, colorants, antistatic agents, lubricants, antioxidants, coupling agents, and foaming agents. Agents, foaming aids and the like. These compounding agents can be appropriately compounded within a range that does not impair the object of the present invention, and commercially available products can be suitably used.

  In the present invention, the above-mentioned mixture of asphalt and vulcanized rubber powder is used as the softener component, but it can also be used in combination with other conventionally known softener components. Examples of such other softening agent components include paraffinic, naphthenic, and aromatic process oils.

  The rubber composition of the present invention is produced by kneading the above components according to a conventional method. The kneading conditions are not particularly limited, and various conditions such as the input volume to the kneading apparatus, the rotational speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of the kneading apparatus, and the like are appropriately selected according to the purpose. be able to. Examples of the kneading apparatus include a Banbury mixer, an intermix, and a kneader that are usually used for kneading a rubber composition.

  The rubber composition of the present invention is preferably used as a vulcanized rubber by kneading, heating, extruding, vulcanizing and the like. The heating conditions are not particularly limited, and various conditions such as the heating temperature, the heating time, and the heating apparatus can be appropriately selected depending on the purpose. As a heating apparatus, the roll machine etc. which are normally used for the heating of a rubber composition are mentioned, for example. Further, the conditions for extrusion are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion apparatus, extrusion temperature and the like can be appropriately selected according to the purpose. As an extrusion apparatus, the extruder etc. which are normally used for extrusion of the rubber composition for tires are mentioned, for example. Furthermore, there is no restriction | limiting in particular also about the apparatus, system, conditions, etc. which perform vulcanization, According to the objective, it can select suitably. Examples of the vulcanizing apparatus include a molding vulcanizer using a mold usually used for vulcanizing a rubber composition for tires. The vulcanization temperature can be, for example, 100 to 190 ° C.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
2 kg of straight asphalt 60/80 (naphthene type) manufactured by JOMO was dissolved at 170 ° C. in a reaction vessel equipped with a heating device equipped with a stirrer. Further, vulcanized rubber powder prepared by kneading the rubber composition having the composition shown in the following Table 1 according to a conventional method and pulverizing the vulcanized rubber obtained by vulcanization to adjust the average particle size to 0.5 mm. Was made. This was put into dissolved asphalt at 250 g and then stirred for 2.5 hours to obtain a mixture of asphalt and vulcanized rubber powder.

＊１）ゴム成分：ＮＲ１００（天然ゴム）
＊２）老化防止剤：大内新興化学工業（株）製，ノクラック６Ｃ
＊３）加硫促進剤：大内新興化学工業（株）製，ノクセラーＤＭ
＊４）加硫促進剤：大内新興化学工業（株）製，ノクセラーＤ

* 1) Rubber component: NR100 (natural rubber)
* 2) Anti-aging agent: Nouchi 6C, manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 3) Vulcanization accelerator: Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller DM
* 4) Vulcanization accelerator: Ouchi Shinsei Chemical Co., Ltd., Noxeller D

  Using the obtained mixture of asphalt and vulcanized rubber powder as a softening agent, rubber compositions of examples were prepared according to the formulation shown in Table 2 below.

(Comparative Example 1)
A rubber composition of Comparative Example 1 was prepared according to the formulation shown in Table 2 below using aroma oil as a softening agent.

(Comparative Example 2)
A comparative example using a mixture of asphalt and vulcanized rubber powder obtained in the same manner as in Example 1 except that naphthenic asphalt was replaced with aroma asphalt as a softening agent, according to the formulation shown in Table 2 below. Two rubber compositions were prepared.

＊５）ＳＢＲ：ＪＳＲ社製，＃０２０２（スチレン含量４０質量％）
＊６）加硫促進剤：大内新興化学工業（株）製，ノクセラーＣＺ

* 5) SBR: JSR, # 0202 (styrene content 40% by mass)
* 6) Vulcanization accelerator: Ouchi Shinsei Chemical Co., Ltd., Noxeller CZ

  About each obtained rubber composition, the fracture | rupture characteristic (Tb) was evaluated in each of room temperature 25 degreeC and high temperature 100 degreeC according to the conventional method. The results are shown as an index with Comparative Example 1 as 100. The higher the number, the better the result. The results are shown in Table 3 below.

  As shown in Table 3, as a result, the rubber composition of Example 1 in which aroma oil (Comparative Example 1) was replaced with a mixture of asphalt and vulcanized rubber powder, and naphthenic one was used as the asphalt. Was confirmed to be more excellent in fracture characteristics.

Claims (5)

  A rubber composition comprising a diene rubber and a mixture of asphalt and vulcanized rubber powder, wherein the asphalt is naphthenic asphalt.   The rubber composition according to claim 1, wherein the mixture of asphalt and vulcanized rubber powder is prepared by mixing and stirring at 120 ° C or higher for 1 hour or longer.   The rubber composition according to claim 1 or 2, wherein the vulcanized rubber powder is obtained from a used rubber product.   The rubber composition according to claim 3, wherein the vulcanized rubber powder is obtained from waste tires.   The rubber composition according to any one of claims 1 to 4, wherein a rubber filler is blended in an amount of 20 to 150 parts by mass with respect to 100 parts by mass of the diene rubber.