JP6486194B2 - Rubber composition - Google Patents

Description

  The present invention relates to a rubber composition.

  Rubber products such as tires, hoses, belts, and anti-vibration rubbers are used in various applications including parts for vehicles. Such a rubber product is blended with an anti-aging agent in order to prevent deterioration due to ozone or oxygen. However, the anti-aging agent has a problem that it easily migrates to the rubber surface and the appearance is impaired.

  Therefore, it has been disclosed that an ether type nonionic surfactant of polyoxyethylene is blended as a method for preventing the migration of the antioxidant to the rubber surface.

JP-A-5-194790

  However, it is difficult to say that the rubber composition of Patent Document 1 has sufficient ozone resistance and heat resistance. Therefore, the present invention provides a rubber composition having excellent ozone resistance and heat resistance.

  In order to solve the above problems, the rubber composition according to the present invention contains a rubber (A) and an alkylene oxide adduct (B) of a saccharide.

  The rubber composition according to the present invention preferably contains 0.5 to 10 parts by mass of the saccharide alkylene oxide adduct (B) with respect to 100 parts by mass of the rubber (A).

  In the rubber composition according to the present invention, the saccharide in the alkylene oxide adduct (B) of saccharide is preferably at least one selected from disaccharides and sugar alcohols.

  The rubber according to the present invention is obtained by vulcanizing the rubber composition.

  According to the present invention, a rubber composition excellent in ozone resistance and heat resistance can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described.

  The rubber composition of this embodiment contains a rubber (A) and an alkylene oxide adduct (B) of a saccharide.

  Examples of the rubber (A) used in the present invention include natural rubber (NR), polyisoprene rubber (IR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), nitrile rubber (NBR), and chloroprene rubber (CR). Ethylene propylene rubber (EPDM), butyl rubber (IIR), halogenated butyl rubber and the like. These rubbers may be used alone or in combination of two or more.

  Examples of the saccharide in the alkylene oxide adduct (B) of saccharide used in the present invention include sugar and sugar alcohol. Examples of the sugar include monosaccharides such as glucose, fructose, galactose and mannose, disaccharides such as sucrose, lactose, maltose and trehalose, polysaccharides such as cellulose, amylose and chitin. Examples of the sugar alcohol include sorbitol, mannitol, maltitol, and erythritol. Of these, disaccharides and sugar alcohols are preferred, and sucrose is more preferred because of its relatively low viscosity and ease of handling, and the appearance of rubber obtained by vulcanizing the rubber composition.

  Examples of the alkylene oxide added to the saccharide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, glycidol, and tetrahydrofuran. Of these, at least one selected from ethylene oxide, propylene oxide and butylene oxide is preferable because compatibility with the rubber (A) is more excellent. At least one selected from ethylene oxide and propylene oxide is preferable. More preferably.

  The amount of alkylene oxide added in the saccharide alkylene oxide adduct (B) is preferably 20 to 500 mol per mol of saccharide. By setting it within the above range, ozone resistance becomes more excellent. The addition amount of the alkylene oxide is more preferably 50 to 400 mol, and further preferably 100 to 350 mol.

  The saccharide alkylene oxide adduct (B) preferably has an average hydroxyl value of 10 to 500 mgKOH / g. By setting it within the above range, ozone resistance becomes more excellent. The average hydroxyl value is more preferably 15 to 300 mgKOH / g, and further preferably 20 to 150 mgKOH / g. The average hydroxyl value can be measured according to JIS K0070.

  The method for adding the alkylene oxide is not particularly limited. For example, in the presence of a saccharide and a catalyst, the alkylene oxide is introduced into a reaction vessel at 70 to 120 ° C. and 0 to 0.3 MPa, and reacted with the saccharide. Is mentioned.

  As the saccharide used for the alkylene oxide addition reaction, saccharide alone can be used, but from the viewpoint of reducing the viscosity of the reaction solution, it is preferable to use saccharide dissolved in a compound capable of dissolving saccharide. Examples of such compounds that can dissolve saccharides include hydroxyl-containing compounds other than saccharides such as water, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, and trimethylolpropane. Of these, water is preferable because of its high solubility in sugars and easy distillation after the addition reaction. Moreover, it is preferable that the usage-amount of the compound which can melt | dissolve saccharides is 20 mass parts or less with respect to 100 mass parts of saccharides from a viewpoint of raising the ratio of the alkylene oxide added to saccharides.

  The catalyst used for the alkylene oxide addition reaction is not particularly limited. For example, alkali metals such as potassium hydroxide and sodium hydroxide, alkaline earth metals such as calcium hydroxide and magnesium hydroxide, diethanolamine, triethylamine and the like. Amines, cationic polymerization catalysts, double metal cyanide complex catalysts, and the like. The usage-amount of a catalyst is 0.01-5.0 mass parts with respect to 100 mass parts of saccharides, for example.

  The alkylene oxide addition reaction product may be further purified. By performing the refining treatment, the rubber composition is more excellent in ozone resistance and heat resistance. Examples of such purification treatment include adsorbent treatment and distillation treatment. Among these, the adsorbent treatment is preferable because the production process is easy.

  The adsorbent treatment method is not particularly limited. For example, the alkylene oxide addition reaction product and the adsorbent are mixed using a stirrer or the like, the alkylene oxide addition reaction product is passed through an adsorbent packed column, and the like. Is mentioned. Among these, the method of mixing the alkylene oxide addition reaction product and activated carbon is preferable because the operation is simple. When a solvent such as water or an organic solvent is used, the adsorbent may be added after mixing with the alkylene oxide addition reaction product in advance, or the adsorbent is dispersed in the solvent and then mixed with the alkylene oxide addition reaction product. May be.

  The adsorbent is for adsorbing and removing impurities contained in the alkylene oxide addition reaction product. Such an adsorbent may be in the form of powder, granules, or pellets, and is preferably in the form of powder. Examples of such an adsorbent include activated carbon, zeolite, and the like. In particular, activated carbon is preferable because the appearance of rubber obtained by vulcanizing a rubber composition is preferable, and the pH in a 1% by mass aqueous suspension is 4. Activated carbon having a pH of ˜11 is more preferable, and activated carbon having a pH of 4.5 to 7.5 is more preferable.

  The amount of the adsorbent used is not particularly limited, but is preferably 0.1 to 20.0 parts by mass, and 1.0 to 10.0 parts by mass with respect to 100 parts by mass of the alkylene oxide addition reaction product. More preferably. By making the usage-amount of adsorption agent in the said range, a manufacturing process will become a simpler thing.

  Moreover, it is preferable to use a solvent in the adsorbent treatment. By using the solvent, the viscosity of the alkylene oxide addition reaction product is reduced, and the purification treatment can be easily performed.

  Moreover, in the said adsorption agent process, you may use various additives, such as antioxidant and a ultraviolet absorber other than the said solvent.

  The content of the alkylene oxide adduct (B) of the saccharide in the rubber composition of the present invention is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber (A). By setting it within the above range, the appearance of rubber obtained by vulcanizing the rubber composition becomes more excellent. The content is more preferably 1.0 to 5.0 parts by mass.

  The method for producing the rubber composition of the present invention is not particularly limited as long as it can mix the rubber (A) and the saccharide alkylene oxide adduct (B). Examples of such a method include a method of mixing using a kneading machine such as an open type twin-screw kneader or a kneader.

  In the said manufacturing method, it is preferable that the mixing temperature of rubber | gum (A) and the alkylene oxide adduct (B) of saccharides is 150-180 degreeC. By setting it as the said range, the external appearance of the rubber | gum which vulcanized the rubber composition will become more excellent.

  The rubber composition of the present invention may contain known additives in addition to the rubber (A) and the saccharide alkylene oxide adduct (B). Examples of such additives include oil, zinc white, wax, vulcanizing agent, vulcanization accelerator, and the like.

  The vulcanized rubber in the present invention is obtained by vulcanizing the rubber composition. The vulcanization method is not particularly limited, and examples thereof include a sulfur vulcanization method and a peroxide vulcanization method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

  In this example, the saccharide alkylene oxide adducts (b-1) to (b-5) obtained in the following Production Examples 1 to 5 were used as the saccharide alkylene oxide adduct (B). The following (b′-1) and (b′-2) were used as alkylene oxide adducts other than the saccharide alkylene oxide adduct (B).

(Production Example 1)
A stainless steel autoclave was charged with 342 g (1 mol) of sucrose, 70 g of water, and 3 g of potassium hydroxide, and the inside of the reactor was purged with nitrogen. The temperature was raised to 80 ° C. to dissolve sucrose, then the temperature was raised to 100 ° C., and 1163 g (20 mol) of propylene oxide was introduced while keeping the internal pressure at 0.3 MPa or less. After completion of the introduction of propylene oxide, an alkylene oxide adduct was obtained by reacting at 100 ° C. for 2 hours.
100 g of the obtained alkylene oxide adduct and 30 g of water were mixed and adjusted to 50 ° C., and acetic acid was further added to adjust the pH to 6. Subsequently, 10 g of powdered activated carbon (trade name: Strong Shirasagi A (manufactured by Nippon Enviro Chemicals, 1% aqueous solution pH: 4.9) was added and stirred for 2 hours at 50 ° C. Thereafter, the activated carbon was removed by filtration. By removing water at 90 ° C. under reduced pressure, sucrose propylene oxide (20 mol) adduct (b-1) was obtained.

(Production Example 2)
A stainless steel autoclave was charged with 68.4 g (0.2 mol) of sucrose, 14 g of water, and 0.6 g of potassium hydroxide, and the inside of the reactor was purged with nitrogen. The temperature was raised to 80 ° C. to dissolve sucrose, then the temperature was raised to 100 ° C., and 232 g (4 mol) of propylene oxide was introduced while keeping the internal pressure at 0.3 MPa or less. After the introduction, the reaction was further carried out at 100 ° C. for 2 hours. Subsequently, 1320 g (30 mol) of ethylene oxide was introduced while maintaining the internal pressure at 100 ° C. and an internal pressure of 0.3 MPa or less. After completion of the introduction, an alkylene oxide adduct was obtained by further reacting at 100 ° C. for 2 hours. The resulting alkylene oxide adduct was purified by the same method as in Production Example 1 to obtain a sucrose-propylene oxide (20 mol) -ethylene oxide (150 mol) block adduct (b-2).

(Production Example 3)
The same operation as in Production Example 2 was performed except that the amount of propylene oxide used was 580 g (10 mol) and the amount of ethylene oxide used was 1584 g (36 mol), and sucrose-propylene oxide (50 mol) -ethylene oxide (180 Mol) Block adduct (b-3) was obtained.

(Production Example 4)
The same operation as in Production Example 2 was performed except that the amount of propylene oxide used was 580 g (10 mol) and the amount of ethylene oxide used was 2200 g (50 mol), and sucrose-propylene oxide (50 mol) -ethylene oxide (250 Mol) Block adduct (b-4) was obtained.

(Production Example 5)
A maltitol-propylene oxide (20 mol) -ethylene oxide (150 mol) block adduct (with the exception of using maltitol 68.8 g (0.2 mol) in place of sucrose) was carried out in the same manner as in Production Example 2. b-5) was obtained.

(B′-1) Compound obtained by adding ethylene oxide (15 mol) to nonylphenol (b′-2) Compound obtained by adding ethylene oxide (15 mol) to stearic acid

(Examples 1-5, Comparative Examples 1-2)
Each material was mixed in the ratio shown in Table 1, and this was uniformly kneaded to obtain a rubber composition. The obtained rubber composition was put into a mold and vulcanized at 180 ° C. for 1 hour to obtain a test piece. Using the obtained test piece, ozone resistance and heat resistance were evaluated by the following methods. The results are shown in Table 2.

(Ozone resistance test)
A strip-shaped test piece having a length of 50 mm, a width of 10 mm, and a thickness of 2 mm was prepared from the obtained rubber composition. This test piece was treated for 48 hours or 96 hours under the conditions of a temperature of 40 ° C., a humidity of 60%, an ozone concentration of 500 ppb, and a test piece elongation of 25% according to the static ozone deterioration test method described in JIS K6259. . The test piece after processing was taken out and the external appearance (color) was confirmed. Further, the number of cracks and the size of the cracks were evaluated according to the following criteria.
[Number of cracks]
-: No crack A: Small number of cracks B: Many cracks C: Numerous cracks [Crack size]
-: No crack 1: Invisible to the naked eye but can be confirmed with a 10-fold magnifier 2: Can be confirmed with the naked eye 3: Cracks are deep and relatively large (less than 1 mm)
4: The crack is deep and large (1 mm or more and less than 3 mm)
5: Those that are likely to cause cracks or cuts of 3 mm or more

(Heat-resistant)
A strip-shaped test piece having a length of 50 mm, a width of 10 mm, and a thickness of 2 mm was prepared from the obtained rubber composition. The specimen was treated at 125 ° C. for 48 hours. The hardness before and after the test was measured according to JIS K6255-2, and the increase rate (%) after the test was evaluated.

  As is clear from Table 2, the rubber composition of the present application is excellent in ozone resistance and heat resistance. On the other hand, as in Comparative Examples 1 and 2, it was found that when an alkylene oxide adduct other than the alkylene oxide adduct (B) of the saccharide of the present application was used, ozone resistance and heat resistance were poor.

  Since the rubber composition of the present invention is excellent in ozone resistance and heat resistance, it can be used for rubber products such as tires, hoses, belts and vibration-proof rubbers.

Claims (4)

A rubber composition comprising a rubber (A), an alkylene oxide adduct of sugars (B) and a vulcanizing agent ,
The rubber (A) is at least one selected from natural rubber and polybutadiene rubber,
The saccharide in the alkylene oxide adduct (B) of the saccharide is at least one selected from disaccharides and sugar alcohols,
The rubber composition in which the addition amount of alkylene oxide in the alkylene oxide adduct (B) of the saccharide is 20 to 500 mol per mol of saccharide .   The rubber composition according to claim 1, comprising 0.5 to 10 parts by mass of an alkylene oxide adduct (B) of a saccharide with respect to 100 parts by mass of the rubber (A).   The rubber composition according to claim 1 or 2, wherein the alkylene oxide in the alkylene oxide adduct (B) of the saccharide is at least one selected from ethylene oxide and propylene oxide. A rubber obtained by vulcanizing the rubber composition according to any one of claims 1 to 3.