JP4764014B2 - Rubber composition and crosslinked rubber using the same - Google Patents

Description

  The present invention relates to a rubber composition and a crosslinked rubber obtained by crosslinking the rubber composition, and particularly relates to a rubber composition that does not cause environmental pollution and has excellent mechanical properties such as elongation at break and tensile stress. .

  Conventionally, in the tire vulcanization process, filling of tire high temperature high pressure gas, steam or hot water and exhaust is alternately repeated in the tire vulcanization bladder, so that the rubber component of the rubber composition for the bladder is mainly butyl rubber (IIR). Is used. This is because butyl rubber is chemically stable as a polymer, has excellent heat resistance, weather resistance, ozone resistance, and is excellent in releasability from other types of rubber. . In the bladder rubber composition containing butyl rubber as a main component, a resol-type alkylphenol-formaldehyde cocondensation resin is generally used as a crosslinking agent (see Patent Documents 1 and 2).

  However, the resol type alkylphenol / formaldehyde cocondensation resin has poor dispersibility in the rubber component. Here, in order to improve the dispersibility of the resin, it is preferable to increase the kneading temperature of the rubber composition. However, when the kneading temperature is 120 ° C. or higher, the crosslinking reaction of the rubber component proceeds during the kneading, A uniform rubber composition cannot be obtained. For this reason, as the crosslinking agent, those having a softening point of 115 ° C. or lower are generally used in view of the balance between dispersibility in the rubber component and the crosslinking reaction initiation temperature.

  In recent years, prevention of environmental pollution has become a social issue, and reduction of impurities, residual raw materials, and residual solvents in rubber products including the bladder is required. Here, in order to reduce impurities and residual raw materials derived from the crosslinking agent in the rubber product, it is effective to reduce alkylphenol, which is the raw material of the crosslinking agent, but in this case, the softening point of the crosslinking agent increases. End up. And since the crosslinking agent with a high softening point has a bad dispersibility to a rubber component, the problem that the rubber physical property of the rubber product finally obtained falls.

JP 7-173202 A JP-A-6-172590

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a rubber composition having sufficient rubber properties without causing environmental pollution. Another object of the present invention is to provide a crosslinked rubber, particularly a tire vulcanization bladder, using such a rubber composition.

  As a result of intensive studies to achieve the above object, the present inventors have found that a resol type alkylphenol / formaldehyde cocondensation resin crosslinking agent containing a predetermined amount of oil and / or plasticizer with a small amount of residual alkylphenol as a raw material is a rubber composition. By using the product, it is possible to prevent environmental pollution caused by the raw material alkylphenol, and since the resin crosslinking agent has a low softening point and good dispersibility in the rubber component, It has been found that deterioration of rubber physical properties can be prevented, and the present invention has been completed.

That is, the rubber composition of the present invention comprises 2 to 25 parts by mass of a resin crosslinking agent with respect to 100 parts by mass of the rubber component.
The resin crosslinking agent, oil in resol type alkylphenol-formaldehyde co-condensed resin crosslinking agent is a and softening point containing from 1 to 30 parts by weight per 100 parts by weight resol type alkylphenol-formaldehyde co-condensed resin 85 to 115 ° C. Yes,
The rubber component is an isobutylene / p-methylstyrene copolymer .

  In a preferred example of the rubber composition of the present invention, the oil in the resin crosslinking agent is a naphthenic oil. In this case, the compatibility of the oil with the resol type alkylphenol / formaldehyde cocondensation resin and the rubber component is good.

  In another preferred embodiment of the rubber composition of the present invention, the content of unreacted alkylphenol in the resin crosslinking agent is less than 1%. In this case, environmental pollution caused by the crosslinking agent can be sufficiently prevented.

  The crosslinked rubber of the present invention is characterized by being formed by crosslinking the rubber composition, and is particularly preferable for use in a bladder.

According to the present invention, a resol-type alkylphenol-formaldehyde cocondensation resin crosslinking agent containing a predetermined amount of oil is blended, and a rubber composition having sufficient rubber properties without causing environmental pollution, and the rubber composition A crosslinked rubber using the product can be provided.

The present invention is described in detail below. The rubber composition of the present invention comprises a resol-type alkylphenol containing 1 to 30 parts by mass of oil to 100 parts by mass of a resol-type alkylphenol / formaldehyde cocondensation resin and having a softening point of 85 to 115 ° C. -It is characterized by containing a formaldehyde co-condensation resin crosslinking agent. In the rubber composition of the present invention, since a resin cross-linking agent containing a specific amount of oil and having a softening point in a specific range is used, the dispersibility of the resin cross-linking agent in the rubber component is good, and the resulting rubber composition Good physical properties.

The resin crosslinking agent contains oil and a resol type alkylphenol / formaldehyde cocondensation resin, and the content of oil in the resin crosslinking agent is 1 to 30 masses per 100 parts by mass of the resole type alkylphenol / formaldehyde cocondensation resin. It is necessary to be in the range of 2 parts by weight, and is preferably in the range of 2 to 25 parts by weight. If the content of oil in the resin cross-linking agent is less than 1 part by mass, the softening point of the resin cross-linking agent does not become low, and the dispersibility of the resin cross-linking agent in the rubber component deteriorates. Problems such as a decrease in hardness of the crosslinked rubber and an increase in compression set occur.

  The resin cross-linking agent used in the rubber composition of the present invention requires a softening point of 85 to 115 ° C, and preferably has a softening point in the range of 90 to 110 ° C. When the softening point of the resin cross-linking agent is less than 85 ° C., resol-type alkylphenol / formaldehyde co-condensation resins tend to adhere to each other during storage of the resin cross-linking agent, so the resin cross-linking agent must be stored at a low temperature, 115 When the temperature exceeds ℃, the dispersibility in the rubber component is poor, and when the kneading temperature is raised to improve the dispersibility, a crosslinking reaction starts during the kneading and a uniform rubber composition cannot be obtained.

  The resol-type alkylphenol / formaldehyde cocondensation resin used for the resin cross-linking agent can be synthesized by a known method described in Plastic Material Course 15 “Phenolic Resin” (published by Nikkan Kogyo Shimbun). Here, in the alkylphenol which is the raw material of the cocondensation resin, the carbon number of the alkyl group is preferably in the range of 1-20. The cocondensation resin preferably has a polystyrene-equivalent weight average molecular weight of 2,000 to 5,000.

  Specific examples of the resol type alkylphenol / formaldehyde cocondensation resin include cresol / formaldehyde cocondensation resin, ethylphenol / formaldehyde cocondensation resin, butylphenol / formaldehyde cocondensation resin, octylphenol / formaldehyde cocondensation resin, butylphenol / octylphenol / formaldehyde Examples include co-condensation resins. These cocondensation resins may be used alone or in combination of two or more.

  The oil used for the resin crosslinking agent is not particularly limited, and naphthenic oil, paraffinic oil, aromatic oil, and the like can be used. Among these oils, the resol type alkylphenol / formaldehyde cocondensation resin is used. Naphthenic oils are preferred because they are excellent in compatibility with the rubber component. These oils may be used alone or in a combination of two or more.

  Examples of the naphthenic oil include Diana Process Oil NS-24, NS-100, NM-26, NM-68, NM-150, NM-280, NP-24, NU-80, NF-90 (above, Idemitsu Kosan Co., Ltd.) Co., Ltd. trade name), Esso Process Oil 725,765 (above, Esso Oil Co., Ltd. trade name), SYNTAC N-40, N-60, N-70, N-75, N-85 (above, Kobe Oil) Chemical Industry Co., Ltd. trade name), shelf rex 371JY, 371N, 451, N-40, 22, 22R, 32R, 100R, 100S, 100SA, 220RS, 220S, 260, 320R, 680 (above, manufactured by Shell Japan Co., Ltd.) Trade name), Kyoishi Process R-50, R-200, R-1000 (trade name made by Nikko Kyoishi Co., Ltd.), Sunthen ne) 310,380,410,415,420,430,450,480,3215,4130,4240, Ciro Light R. P. O. (Nippon Sun Oil Co., Ltd. trade name), Komo Rex No. 2, Komo Rex F22 (Nippon Oil Co., Ltd. trade name), Fukkor 1150N, 1400N (Fuji Kosan Co., Ltd. trade name), Mitsubishi 20 ( Mitsubishi Oil Co., Ltd. trade name), Naplex 32, 38 (above, Mobil Sekiyu Co., Ltd. trade name), Petrex PN-3 (Yamabun Yuka Co., Ltd. trade name), and the like.

  Examples of the paraffinic oil include Diana process oils PW-32, PW-90, PW-150, PW-380, PS-32, PS-90, PS-430, PX-32, and PX-90. (Trade name made by Co., Ltd.), stanol 40, 43N, 52, 69, 149, LP40, LP69, flexon 845 (above, trade name made by Esso Oil Co., Ltd.), syntax PA-95, PA-100, PA-140 (above , Kobe Oil Chemical Co., Ltd. trade name), Cosmo Process 10, 40, 40C (above, Cosmo Oil Co., Ltd. trade name), Lubflex 26, 100, 400 (above, Shell Japan Corporation trade name), Kyoishi process P-200, P-300, P-500 (above, Nikko Kyoishi Co., Ltd., trade name), Thamper 11 , 115, 120, 130, 150, 180, 2100, 2210, 2280 (above, product names manufactured by Nippon Sun Oil Co., Ltd.), Fukkor P-200, P-400, P-500 (above, products manufactured by Fuji Kosan Co., Ltd.) Name), Mitsubishi 10, Mitsubishi 12 (above, trade name manufactured by Mitsubishi Oil Corporation), and the like.

  Examples of the aromatic oil include Diana Process Oil AC-12, AC-460, AE-24, AE-50, AE-200, AH-16, AH-58 (above, trade name of Idemitsu Kosan Co., Ltd.), Esso process oil 110, 120 (above, trade name made by Esso Oil Co., Ltd.), SYNTAC HA-10, HA-15, HA-30, HA-35 (above, trade name made by Kobe Oil Chemical Co., Ltd.), Cosmo Process 40A (trade name manufactured by Cosmo Oil Co., Ltd.), Dutrex 729UK, 739 (above, product name manufactured by Shell Japan Co., Ltd.), Kyoishi Process X100-A, X100 (above, product name manufactured by Nippon Mining & Co., Ltd.), JSO Aroma 790 (trade name, manufactured by Nippon San Oil Co., Ltd.), Komolex 300,700 (above, product name manufactured by Nippon Oil Corporation), aroma # 1, # 3, # 5 (trade name, manufactured by Fuji Kosan Co., Ltd.) Heavy Process Oil Mitsubishi 34, Mitsubishi 38, Mitsubishi 44 (trade name, manufactured by Mitsubishi Oil Corporation), Mobilsol K, 22, 30 , 130 (above, trade name made by Mobile Oil Co., Ltd.), Petrex LPO-R, LPO-V, PF-1, PF-2 (above, trade name made by Yamabun Yuka Co., Ltd.), and the like.

The method of mixing the resol type alkylphenol / formaldehyde cocondensation resin and oil is not particularly limited. For example, after the oil is uniformly dissolved in the organic solvent solution of the resol type alkylphenol / formaldehyde cocondensation resin, the organic solvent is retained. a method of causing removed by being the most convenient way, may be adopted a method of mixing with oil at a temperature above the softening point of the co-condensation resin. Here, when an organic solvent is used for mixing, the content of the organic solvent remaining in the resin crosslinking agent is preferably less than 1% from the viewpoint of preventing environmental pollution.

  The resin crosslinking agent used in the rubber composition of the present invention preferably has an unreacted alkylphenol content of less than 1%. If the content of unreacted alkylphenol in the resin crosslinking agent is less than 1%, the amount of alkylphenol remaining in the rubber composition and the crosslinked rubber obtained by crosslinking it is low, and environmental pollution is sufficiently prevented. Can do.

The rubber component used in the rubber composition of the present invention is an isobutylene / p-methylstyrene copolymer . When a rubber composition is used for a bladder, an isobutylene / p-methylstyrene copolymer is most preferable because of excellent chemical stability. Since the rubber composition in which the rubber component is an isobutylene / p-methylstyrene copolymer is particularly excellent in heat aging resistance, the life of the bladder can be greatly extended by applying the rubber composition to the bladder.

In the rubber composition of the present invention, the amount of the resin crosslinking agent is in the range of 2 to 25 parts by mass with respect to 100 parts by mass of the rubber component. When the blending amount of the resin crosslinking agent is less than 2 parts by mass with respect to 100 parts by mass of the rubber component, the rubber composition cannot be sufficiently crosslinked, and the rubber properties of the resulting crosslinked rubber are lowered, whereas 25 parts by mass If it exceeds, the hardness will increase too much and the physical properties of the rubber will decrease.

  The rubber composition of the present invention may contain a crosslinking accelerator such as chloroprene rubber (CR), tin chloride, benzenesulfonic acid, calcium oxide, molecular sieve, etc., in order to promote the crosslinking reaction by the resin crosslinking agent. Good.

  In addition to the resin crosslinking agent, the rubber component and the crosslinking accelerator, the rubber composition of the present invention includes a compounding agent usually used in the rubber industry, for example, a filler such as carbon black, zinc oxide, stearin. Acids, oils and the like can be appropriately selected and blended within a range that does not impair the object of the present invention, and commercially available products can be suitably used as these blending agents. In addition, the said rubber composition can be manufactured by mix | blending a resin crosslinking agent and the various compounding agents selected suitably as needed to a rubber component, kneading | mixing, heat-inserting, extrusion.

  The crosslinked rubber of the present invention is obtained by crosslinking the rubber composition described above. Here, the crosslinking temperature is not particularly limited, but is preferably in the range of 120 to 230 ° C. The crosslinked rubber can be used as various rubber products, and can be particularly suitably used as a tire vulcanization bladder.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Preparation of resin crosslinking agent A)
According to a known method, a resol-type p-octylphenol / formaldehyde co-condensation resin having a residual p-octylphenol content of less than 1.0% was synthesized using formaldehyde and p-octylphenol as raw materials and an alkali catalyst. Next, 12% by mass of Komolex F22 [Naphthenic oil manufactured by Japan Petroleum Corporation] was added to 88% by mass of the cocondensation resin in the toluene solution of the obtained cocondensation resin. Thereafter, toluene was distilled off under reduced pressure to obtain a resin crosslinking agent A.

(Preparation of resin crosslinking agent B)
Resin crosslinking agent B was prepared in the same manner as in the preparation of resin crosslinking agent A, except that the blending amount of Komulex F22 was changed to 8% by mass with respect to 92% by mass of cocondensation resin.

(Preparation of resin crosslinking agent C)
Resin cross-linking agent C was prepared in the same manner as the resin cross-linking agent A, except that the amount of humorex F22 was changed to 4% by mass with respect to 96% by mass of the co-condensation resin.

(Preparation of resin crosslinking agent D)
Resin cross-linking agent D was prepared in the same manner as the resin cross-linking agent A, except that humorex F22 was not blended.

(Preparation of resin crosslinking agent E)
Resin cross-linking agent E was prepared in the same manner as the resin cross-linking agent A, except that the amount of humorex F22 was changed to 20% by mass with respect to 80% by mass of the co-condensation resin.

  The amount of residual p-octylphenol and the softening point of the resin crosslinking agents A to E obtained as described above were measured by the following methods, and the results are shown in Table 1. For comparison, the amount of p-octylphenol remaining and the softening point of Taccolol 201 manufactured by Taoka Chemical Industry Co., Ltd. were measured, and the results are also shown in Table 1.

(1) Measurement of residual p-octylphenol amount 0.1 g of anisole as an internal standard substance was added to 1 g of a resin cross-linking agent, dissolved in 20 mL of acetone, and measured by gas chromatography.

(2) Measurement of softening point The softening point of each resin crosslinking agent was measured according to JIS K2207.

  Next, using a Toyo Seiki Lab Plast Mill Roller Mixer (chamber capacity 60 cc), 50 g of a rubber composition having the formulation shown in Table 2 was kneaded for 15 minutes at a set temperature of 90 ° C., and the resulting rubber was obtained. The composition was sheet-formed with a roll to a thickness of 0.5 mm, and the presence or absence of aggregates was visually observed. Here, the dispersibility of the sheet without agglomerates was rated as ◯, the dispersibility of the sheets with agglomerates as x, and the evaluation results are shown in Table 2. Further, the obtained rubber composition was subjected to a tensile test by the following method, and the results are shown in Table 2.

(3) Tensile test Tensile strength (Tb), elongation at break (Eb), and tensile stress at 300% elongation of a crosslinked rubber obtained by performing a tensile test in accordance with JIS K6251 and crosslinking at 190 ° C for 30 minutes. (M ₃₀₀ ) was measured, and the retention ratio of the tensile strength after aging with respect to the initial tensile strength was calculated. The tensile strength (Tb) after aging of the crosslinked rubber was measured after aging the crosslinked rubber at 180 ° C. for 24 hours.

* 1 Made by JSR, Butyl1268.
* 2 Showa Neoprene, Neoprene W.
* 3 EXXPRO 3035, manufactured by EXXON MOBIL.
* 4 Tokai Carbon, Seast 600A.

As is clear from Tables 1 and 2, the rubber compositions of Examples and Reference Examples in which resin cross-linking agents A to C having a softening point of 85 to 115 ° C. were blended by blending a specific amount of oil, In the same manner as in the rubber composition of Comparative Example 3 containing No. 1, no agglomerates were observed, the dispersibility of the resin cross-linking agent in the rubber component was good, and the tensile strength, elongation at break, and tensile stress were also compared. It was equivalent to the rubber composition of Example 3. In addition, since resin cross-linking agents A to C have a smaller amount of p-octylphenol remaining than tack roll 201, the rubber compositions of Examples and Reference Examples are used for rubber products to prevent environmental pollution. Can do.

Moreover, it turns out that the fall of the physical property after aging can be suppressed from the comparison with the reference example 1 and Example 4 by using an isobutylene and p-methylstyrene copolymer as a rubber component.

On the other hand, the rubber composition of Comparative Example 1 containing no resin and containing a resin crosslinking agent D having a too high softening point had poor dispersibility of the resin crosslinking agent in the rubber component. Further, the rubber composition of Comparative Example 2 containing an excessive amount of oil and a resin cross-linking agent E having a too low softening point had low tensile stress and reduced rubber rigidity.

Claims (6)

It is composed of 2 to 25 parts by mass of a resin cross-linking agent with respect to 100 parts by mass of the rubber component.
The resin crosslinking agent, oil in resol type alkylphenol-formaldehyde co-condensed resin crosslinking agent is a and softening point containing from 1 to 30 parts by weight per 100 parts by weight resol type alkylphenol-formaldehyde co-condensed resin 85 to 115 ° C. Yes,
A rubber composition, wherein the rubber component is an isobutylene / p-methylstyrene copolymer . The rubber composition according to claim 1, wherein the oil in the resin crosslinking agent is at least one selected from naphthenic oil, paraffinic oil, and aromatic oil. The rubber composition according to claim 2 , wherein the oil in the resin crosslinking agent is a naphthenic oil.   The rubber composition according to claim 1, wherein the content of unreacted alkylphenol in the resin crosslinking agent is less than 1%. A crosslinked rubber obtained by crosslinking the rubber composition according to claim 1 . The crosslinked rubber according to claim 5 , which is used for a bladder.