JP2001158838A - Rubber product and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber product having no blooming of white filler. SOLUTION: This rubber product is a rubber product obtained by vulcanizing and molding a rubber composition comprising a rubber component, a crosslinking agent and a white filler and is characterized in that a part subjected to ultraviolet irradiation treatment is contained in at least a part of the external surface of the rubber product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber product and a method for producing the same, and more particularly, to a rubber product suitably used for sports shoes such as golf shoes and shoe soles such as trekking shoes. This is to prevent the white filler compounded in the rubber product on the surface from depositing on the outer surface.

[0002]

2. Description of the Related Art In rubber products, a crosslinking reaction is carried out by adding a compounding agent such as a vulcanizing agent, an antioxidant, and various fillers (filler for increasing and / or reinforcing) to a rubber component (polymer rubber) as a base material. It is used in a very wide range of fields, including industrial products such as automobiles, footwear, rubberized cloth, and golf balls, by applying its unique property rich in elasticity. In general, such a rubber product is formed by forming a cross-link between rubber molecular chains of a rubber substrate by a chemical reaction.
The desired elasticity is imparted by forming a three-dimensional network structure, and various changes tend to occur over time.

[0003] One of them is a phenomenon called blooming (or blooming) in which a compounded chemical blows out to the surface, and as a result, the appearance of the product is impaired and the quality of the rubber product is deteriorated. This blooming phenomenon is a phenomenon caused by the transfer of a specific compounding agent from the inside of the rubber to the surface, and such a chemical usually has some solubility. Therefore, in order to avoid the blooming phenomenon, a solution has conventionally been attained by reducing the amount of the chemical in question or replacing it with a chemical having good compatibility.

[0004]

As described above, conventionally,
The known bloom phenomenon was caused by "soluble substances" and the solution was known, but it has recently been found that the same phenomenon occurs even with inorganic fillers added as white fillers. Was. In order to avoid the blooming of rubber products due to such "insoluble substances", the amount of the filler in question must be reduced or replaced with another filler which does not easily cause the blooming.
If the white filler is merely used for the purpose of increasing the amount, it is possible to take measures such as selecting the filler as appropriate, but if the white filler is used for the purpose of reinforcement (improvement of physical properties), the filling may be performed. Changing or reducing the amount of the agent may impair the essential properties and durability of the rubber product and is not easy. In particular, when producing a light-colored rubber product such as a white or light color, a white filler is essential. Therefore, in order to obtain a product that is qualitatively satisfactory in both appearance and structure of the product, it is necessary to reduce the bloom phenomenon. There has been a strong need for a method of suppressing this.

The present invention has been made in view of the above problems, and has as its object to easily and surely suppress the occurrence of the bloom phenomenon even when a white filler is blended.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a rubber product obtained by vulcanizing a rubber composition containing a rubber component, a crosslinking agent and a white filler. An object of the present invention is to provide a rubber product characterized in that at least a part of the surface is provided with a portion on the outer surface of which an ultraviolet irradiation treatment is applied to reduce the precipitation of the white filler.

According to the present invention, when a rubber product obtained by vulcanization molding from a rubber composition containing a usual vulcanization molding compound is subjected to ultraviolet irradiation treatment of a certain strength, a bloom phenomenon originally occurs. It is based on the finding that bloom is suppressed even in the case of blending.

The rubber component (polymer component) contained in the rubber composition includes styrene-butadiene rubber (SBR)
, Butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NB
R), chloroprene rubber (CR), ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR), acrylic rubber (ACM, ANM), epichlorohydrin rubber (CO, EC
O), polysulfide rubber (T), urethane rubber (U), etc., and these can be used alone or in combination of two or more.

The crosslinking agent can be arbitrarily selected from those known in the art, and examples thereof include sulfur, organic sulfur-containing compounds, organic peroxides, and quinone dioximes. When a crosslinking agent (vulcanizing agent) for sulfur or an organic sulfur-containing compound is used, a vulcanization accelerator or a vulcanization accelerator may be used. Examples of the vulcanization accelerator include inorganic accelerators such as slaked lime, magnesia (MgO) and litharge (PbO), thiazole vulcanization accelerators, sulfenamide vulcanization accelerators, thiuram vulcanization accelerators, An organic accelerator such as a dithiocarbamate-based vulcanization accelerator can be used.
Further, a vulcanization accelerating aid can be blended, and for example, a metal compound such as zinc white and a fatty acid such as stearic acid, oleic acid and cottonseed fatty acid can be used.

The white filler is selected from white or light-colored inorganic or organic fillers usually used for improving physical properties of rubber products (adjustment of viscoelasticity, provision of wear resistance, adjustment of hardness, etc.). Is done. The inorganic filler includes fillers other than carbon, and examples thereof include silica, clay, calcium carbonate, magnesium carbonate, talc, and zinc white. Further, examples of the organic filler include a high styrene resin, a phenol resin, and a cumarone resin, and an inorganic filler other than carbon is preferable. In particular, in the present invention, silica, which is a filler having a high reinforcing effect and a small particle size, is preferably used. Silica (white carbon) used as a reinforcing agent for crosslinked rubber generally has a primary particle size of 10 to 5
It is an ultra-fine white powder of 0 nm and is classified into dry white carbon, wet white carbon, colloidal silica, fumed silica and the like according to the production method, and can be appropriately selected therefrom.

The amount of the white filler in the rubber composition varies depending on the type of the rubber product. However, since the blooming tends to be remarkable as the amount of the compound increases, the present invention mainly relates to the present invention. For products that require relatively large amounts. Specifically, the bloom suppressing effect in the rubber product of the present invention was obtained by vulcanization molding from a rubber composition containing at least 10 parts by weight, preferably at least 30 parts by weight of a white filler with respect to 100 parts by weight of a rubber component. It is better demonstrated in rubber products.

When a white filler is blended as a reinforcing agent,
The amount of the other components in the composition, the type of filler,
Depending on the type of product, it is usually 20 to 90 parts by weight, preferably 30 to 80 parts by weight, per 100 parts by weight of the rubber component.
Parts by weight. For example, in the case of outsole of footwear, the white filler is blended in an amount of 10 to 80 parts by weight, preferably 30 to 70 parts by weight, based on 100 parts by weight of the rubber component.

The above-mentioned compounding amount is not limited, and can be appropriately selected and set according to the purpose, such as the relationship with rubber products and other compounding agents.

[0014] The rubber composition may also contain other additives commonly used in the art.
Antioxidants, softeners (plasticizers) and the like are included. further,
A silane coupling agent, a silylating agent or the like may be blended for imparting water repellency and adjusting viscoelasticity.

The present invention includes any rubber product vulcanized and molded from a rubber composition containing a rubber component, a cross-linking agent and a white filler, while maintaining a certain quality in both the effect of ultraviolet irradiation and the appearance. Suitable for products that are required to do so. Examples of such products include an outsole for footwear, a rubber member disposed at the tip of a cane, a non-slip member disposed on a stair, and the like. Examples of the footwear include trekking shoes, golf shoes, tennis shoes, jogging shoes, and other outdoor shoes, indoor sports shoes, boots, casual shoes, sandals, and the like.

The ultraviolet irradiation can be applied to the whole product, but usually, it is necessary to reinforce it by adding a certain amount of a white filler, and it may be locally applied to a portion where the bloom phenomenon becomes a problem. Such parts are different for each rubber product,
Of the footwear, the bottom is the bottom and / or the side of the shoe sole for shoes, and the bottom is for sandals.

The rubber product of the present invention can be obtained by vulcanizing and molding a rubber composition containing the above compounding agent according to a conventional method, and irradiating a desired portion with ultraviolet rays.

As for the condition of the ultraviolet irradiation, the stronger the ultraviolet light to be irradiated and the longer the irradiation time, the greater the effect of preventing bloom. However, UV light is too strong,
If the rubber is irradiated for a long time, the rubber may be deteriorated or discolored, which may cause deterioration of the quality of the product. Therefore, when the illuminance of UV irradiation (a value measured by a UV meter at a distance of 240 mm from the center of the light source with a UV meter) is represented by A (mW / cm ² ) and the irradiation time is represented by B (sec), A The value of × B is determined in consideration of not only the bloom suppressing effect but also the effect on the quality of the rubber product and the cost.

Usually, the lower limit of A × B is 1,000, preferably 1200, and the upper limit is 10,000,00.
0, preferably 5,000,000. If it is less than 1,000, the bloom suppressing effect is insufficient, and
If it exceeds 000, the blooming effect does not change much, but there is a possibility that discoloration and physical properties may be deteriorated due to deterioration of the product surface due to ultraviolet rays, and the cost is high. Therefore, the above range is appropriate.

In implementing the present invention, A (illuminance) × B
Appropriate A and B are determined so that (time) falls within the above range. Naturally, if A is large, the irradiation time is short, and if it is converse, long irradiation is required. Therefore, if A is large, productivity is improved by shortening the time, but the apparatus is expensive, and conversely, if A is small, productivity is reduced. Therefore, A is 50 to 1500, preferably 200 to 100.
And B is 10 to 10,000, preferably 1
It is better to be in the range of 5 to 600.

The ultraviolet irradiation treatment can be performed using a commercially available appropriate device. Examples of such a device include an eye super UV tester “SUV-W13” (Iwasaki Electric) and “N
UX7324F "(Matsushita Electric Works) and the like.

Under the above conditions, the rubber product of the present invention subjected to the ultraviolet irradiation treatment did not cause the bloom phenomenon even after being left for one month in the shade outdoors and maintained the quality, as described later.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Table 1 below shows the composition of the rubber product.

[0024]

[Table 1]

In Table 1, * 1 to * 6 are as follows. * 1 Solution-polymerized styrene-butadiene rubber (manufactured by Nippon Zeon) * 2 Ultrasil VN3 (manufactured by Degussa) * 3 Old anti-crack 200 (manufactured by Ouchi Shinko Chemical) Chemical name: 2,6-di-tert-butyl-4-methyl Phenol * 4 Noxeller NS (Ouchi Shinko Chemical) Chemical name: N
-Tert-butyl-2-benzothiazyl-sulfenamide * 5 Noxeller EZ (Ouchi Shinko Chemical) Chemical name: zinc diethyldithiocarbamate * 6 Noxeller DT (Ouchi Shinko Chemical) chemical name: di-orthotril guanidine

The rubber composition shown in Table 1 was filled in a mold and press-vulcanized in a mold at 160 ° C. for 15 minutes to prepare a test piece of a rubber product for testing. Next, a commercially available ultraviolet irradiation device NUX7324F was applied to the surface of the obtained rubber product.
Using (Matsushita Electric Works), ultraviolet irradiation treatment was performed under the conditions shown in Table 2 below (Examples 1 to 3). On the other hand, a rubber product obtained in the same manner and not subjected to ultraviolet irradiation treatment (Comparative Example 1) and a product irradiated with ultraviolet light at A × B = 350 (Comparative Example 2) were prepared.

The above Examples 1 to 3 and Comparative Examples 1 and 2 were dried in a humid outdoor shade for one month, and visually examined for the presence of blooming on the surface for comparative study. During this time, the average temperature was about 30 ° C. and the humidity was about 50%. When whitening was observed, it was evaluated as x, and when it was not observed, it was evaluated as ○, and the results shown in Table 2 below were obtained.

[0028]

[Table 2]

As apparent from Table 2, the products of Comparative Examples 1 and 2 showed whitening due to silica blooming, whereas the rubber products of Examples 1 to 3 did not show whitening.

[0030]

As is apparent from the above description, according to the present invention, by irradiating ultraviolet rays, blooming due to a white filler in a crosslinked rubber product is suppressed, so that a sufficient reinforcing effect can be obtained. And a rubber product having excellent characteristics in both appearance and durability can be obtained.

The rubber product of the present invention is an outsole for footwear which is required to have not only appearance but also durability.
When the UV-irradiated portion is on the bottom and / or side surface, the quality can be improved, and the effect is large.

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Claims (6)

[Claims] 1. A rubber product obtained by vulcanizing and molding a rubber composition containing a rubber component, a crosslinking agent and a white filler, wherein at least a part of the outer surface is subjected to an ultraviolet irradiation treatment, and A rubber product comprising a portion in which precipitation of the white filler is reduced. 2. The compounding amount of the white filler in the rubber composition is as follows:
2. The rubber product according to claim 1, wherein the amount is from 10 parts by weight to 80 parts by weight based on 100 parts by weight of the rubber component. 3. The rubber product according to claim 1, wherein the white filler is silica. 4. The method according to claim 1, wherein the illuminance of the irradiated ultraviolet light is A (mW / c
m ² ), and when the irradiation time is B (sec), A × B in the ultraviolet irradiation treatment is 1000 to 10,000,000,000
The rubber product according to any one of claims 1 to 3, wherein the rubber product is 0 or less. 5. The rubber product according to claim 1, wherein the rubber product is a shoe sole, and the portion subjected to the ultraviolet irradiation treatment is a bottom surface and / or a side surface of the shoe sole. . 6. A rubber composition containing a rubber component, a cross-linking agent and a white filler is vulcanized and molded, and at least a part of the outer surface of the molded article is subjected to an ultraviolet irradiation treatment so that the outer surface of the white filler has a white filler. A method for producing a rubber product, wherein precipitation is reduced.