阅读说明：本技术 橡胶组合物和使用其的降低对混炼机表面的粘合性的方法 (Rubber composition and method for reducing adhesion to surface of kneading machine using same ) 是由 古贺敦 于 2019-03-14 设计创作，主要内容包括：本发明提供一种橡胶组合物,所述橡胶组合物中每100重量份的乙烯·丁烯·5-亚乙基-2-降冰片烯三元共聚物以20重量份～60重量份的比例含有DBP吸油量为100ml/100g以上且碘值为75g/kg～90g/kg的炭黑,所述橡胶组合物考虑了混炼加工性,可降低对混炼机、特别是开放式辊混炼机表面的粘合性。该橡胶组合物可获得稳定且安全的生产率,可用于在约-30～-60℃的低温环境下特别需要高压气体密封功能的密封部件。(The present invention provides a rubber composition containing 20 to 60 parts by weight of carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 75 to 90g/kg per 100 parts by weight of an ethylene-butene-5-ethylidene-2-norbornene terpolymer, which can reduce the adhesion to the surface of a kneader, particularly an open roll kneader, in consideration of the kneading processability. The rubber composition can be used for sealing parts which particularly require a high-pressure gas sealing function in a low-temperature environment of about-30 to-60 ℃ with stable and safe productivity.)

1. A rubber composition characterized by containing, as a main component,

the rubber composition contains 20 to 60 parts by weight of carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 75 to 90g/kg per 100 parts by weight of an ethylene/butene/5-ethylidene-2-norbornene terpolymer, and the adhesiveness to the surface of a kneader is reduced.

2. The rubber composition according to claim 1, wherein carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 30 to 130g/kg but not including 75 to 90g/kg is used together in an amount of 50 parts by weight or less.

3. The rubber composition according to claim 1, wherein silica is used together in a proportion of 50 parts by weight or less.

4. The rubber composition according to claim 1, wherein 1 to 20 parts by weight of a processing aid or a lubricant is used together.

5. A sealing member comprising a peroxide crosslinked molded article of the rubber composition according to claim 1.

6. A method for reducing the adhesion to the surface of a kneader, characterized by using a rubber composition containing 20 to 60 parts by weight of carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 75 to 90g/kg per 100 parts by weight of an ethylene-butene-5-ethylidene-2-norbornene terpolymer.

Technical Field

The present invention relates to a rubber composition and a method for reducing adhesion to a surface of a kneader using the same. More particularly, the present invention relates to an ethylene-butene-5-ethylidene-2-norbornene terpolymer rubber composition and a method for reducing the adhesion to the surface of a kneader by using the same.

Background

Ethylene-propylene-diene copolymer rubber (EPDM) that exhibits sealing properties at both high and low temperatures has no unsaturated bond in the main chain, and therefore, rubber strength and low temperature properties are in conflicting relationship with an increase in ethylene content. Therefore, the EPDM composition has difficulty in achieving sealability at low temperatures exceeding a certain temperature limit.

In order to obtain a rubber molded article which can maintain the same level of hardness as a rubber molded article using a conventional EPDM and has particularly excellent low-temperature rubber characteristics, the present applicant has previously proposed a rubber composition comprising an ethylene/butene/ethylidene norbornene terpolymer [ EBENB ], carbon black, a hardness adjuster and a crosslinking agent (patent document 1).

The carbon black used in the rubber composition is not particularly limited, and known carbon blacks such as FEF carbon black and SRF carbon black are used, but in each example, only carbon black is used.

Patent document 2, which describes an ethylene-butene-nonconjugated polyene copolymer, describes that various Carbon blacks can be used as reinforcing agents in a rubber composition containing the copolymer, and particularly preferably Asahi Carbon products Asahi #55G (gpf), Asahi #50HG (super), Asahi #60G (FEF), and Tokai Carbon product set FEF (FEF), and in examples, Asahi Carbon product Asahi #60G is used as a FEF Carbon black.

However, EBENB has very high adhesiveness of a polymer copolymer, and adheres to the surface of a kneader, particularly an open roll kneading machine, resulting in very poor productivity in a kneading step of a rubber composition, and has a problem that there is a possibility of safety hazard, foreign matter mixing, and the like due to intrusion of hands and arms of an operator into a dangerous area between two open rolls (bank) during a tumbling operation.

Disclosure of Invention

Technical problem to be solved by the invention

The purpose of the present invention is to provide an ethylene/butene/5-ethylidene-2-norbornene terpolymer rubber composition to which carbon black having specific properties is added, which can reduce the adhesion to the surface of a kneader in consideration of kneading processability.

Means for solving the problems

The object of the present invention is achieved by a rubber composition which contains 20 to 60 parts by weight of carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 75 to 90g/kg per 100 parts by weight of an ethylene-butene-5-ethylidene-2-norbornene terpolymer and can reduce the adhesion to the surface of a kneader.

Also disclosed is a method for reducing the adhesion of a rubber composition to the surface of a kneader.

ADVANTAGEOUS EFFECTS OF INVENTION

The rubber composition of the present invention can effectively reduce the adhesion to the surface of a kneader, particularly an open roll kneader, by blending carbon black having specific properties. And stable and safe productivity can be obtained.

The rubber composition is useful for a seal member particularly requiring a high-pressure gas seal function in a low-temperature environment of about-30 ℃ to-60 ℃.

Detailed Description

In the rubber composition, the characteristics of the rubber material such as EBENB or EPDM greatly affect the material cost and the production efficiency of the entire rubber composition. Since EBENB has better cold resistance than EPDM, a rubber composition having desired low-temperature rubber characteristics can be realized in a smaller amount than EPDM, and the material cost can be reduced as the whole rubber composition.

Furthermore, EBENB has excellent flexibility as compared with EPDM, and thus has excellent processability such as kneading property, dispersibility, and moldability, and the production efficiency is greatly improved, so that the cost of the production process can be reduced.

According to the rubber composition of the present invention using EBENB as described above, the production cost of the rubber molded product can be reduced from the viewpoint of the material cost and the production efficiency as compared with the conventional rubber composition using EPDM.

As EBENB, any EBENB obtained by copolymerizing ethylene and butene with a small amount (about 0.1 to 20 wt%, preferably about 3 to 15 wt%) of 5-ethylidene-2-norbornene can be used, and a commercially available product, for example, metalocene EBT, which is a chemical product of mitsui, can be used as it is.

The iodine value of EBENB is preferably about 3g/100g to 20g/100g, more preferably 5g/100g to 18g/100 g. By setting the molecular weight in the above range, the rubber molded article can be prevented from aging due to excellent heat aging resistance and weather resistance, and a stable molecular state can be maintained even in a low-temperature environment, thereby improving low-temperature sealing properties.

Furthermore, EBENB has a Mooney viscosity ML comparable to EPDM₁₊₄The polymer viscosity (100 ℃) is small, and it can be said that the polymer is excellent in processability (e.g., kneading property or moldability). Therefore, by using EBENB instead of EPDM, productivity such as molding efficiency can be improved, and production cost can be reduced.

Mooney viscosity ML of this EBENB₁₊₄The temperature (100 ℃) is preferably about 10 to 45, and more preferably about 15 to 35. If the Mooney viscosity is too low, the compression set becomes large and the tensile strength becomes small in some cases. On the other hand, if the Mooney viscosityIf too high, the properties may be improved, but the processability may be poor. Note that the Mooney viscosity ML is₁₊₄(100 ℃) can be calculated in accordance with the provisions of JIS K6300-1: 2013.

The content of the ethylene component in EBENB is preferably about 60 to 80 wt%, and more preferably about 65 to 75 wt%. By setting the glass transition temperature Tg of EBENB to the minimum value, the cold resistance can be improved.

EBENB and EPDM may be used together within a range not impairing the object of the present invention. Further, if necessary, a hardness modifier such as silicic acid, calcium carbonate, magnesium carbonate, clay, talc, bentonite, sericite, mica, calcium silicate, hydrated alumina, or barium sulfate, or a resin filler such as polyethylene, polypropylene, polystyrene, coumarone-indene resin, melamine resin, or phenol resin may be used in combination.

As the carbon black [ CB ], a carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 75 to 90g/kg, preferably 80 to 85g/kg, can be used. The carbon black is mainly HAF type carbon black, but HAF-LS-SC (S-315) and HAF-LS (N-326) are not included even in HAF type carbon black because the DBP oil absorption thereof is less than a predetermined value.

When the DBP oil absorption is 100ml/100g or less, the desired adhesiveness to the surface of the kneading machine cannot be completely reduced. When the iodine value is within the above range, the effect of reducing the adhesiveness to the surface of the kneader is insufficient, while when the iodine value is within the above range, the effect of reducing the adhesiveness is insufficient and the dispersibility of the filler is also insufficient.

The carbon black having the above properties is used in a proportion of about 20 to 60 parts by weight per 100 parts by weight of EBENB. When the compounding ratio is less than the above range, the effect of lowering the adhesiveness cannot be sufficiently exhibited, while when the compounding ratio is more than the above range, particularly when an open roll kneader is used, the rubber may not be wound.

Further, carbon black having a DBP oil absorption of 100ml/100g or more and an iodine value of 30g/kg to 130g/kg (excluding 75g/kg to 90g/kg) may be used together in an amount of 50 parts by weight or less per 100 parts by weight of EBENB. The total amount of the two carbon blacks is preferably about 20 to 80 parts by weight.

Further, silica may be used as a filler at a ratio of 50 parts by weight or less per 100 parts by weight of EBENB. In the case of using silica, various silane coupling agents are preferably used. The total amount of the carbon black and the silica having predetermined properties is preferably about 20 to 100 parts by weight.

As the crosslinking agent, it is preferable to mainly use an organic peroxide. Examples of the organic peroxide include: t-butyl peroxide, dicumyl peroxide, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, 2, 5-dimethyl-2, 5-di-t-butylperoxy-3-hexyne, t-butylcumyl peroxide, 1, 3-di-t-butylperoxyisopropyl benzene, 2, 5-dimethyl-2, 5-di (benzoyl peroxide) hexane, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, n-butyl-4, 4-di-t-butylperoxyvalerate, and the like.

The amount of the crosslinking agent blended is preferably about 0.5 to 10 parts by weight, more preferably about 1 to 5 parts by weight, based on 100 parts by weight of EBENB. By setting the amount to the above range, it is possible to prevent the molding from being disabled by foaming at the time of vulcanization, and since the crosslinking density becomes good, it becomes easy to obtain a molded article having sufficient physical properties.

In addition, a master batch containing the organic peroxide as described above may also be used. The master batch is preferable in that the kneading property and dispersibility in the preparation of the rubber composition can be improved.

Further, a crosslinking accelerator may be contained as necessary. As the crosslinking accelerator, triallyl isocyanurate, triallyl cyanate, liquid polybutadiene, N' -m-phenylene bismaleimide, trimethylolpropane trimethacrylate, or the like can be used. By adding a proper amount of a crosslinking accelerator, the crosslinking efficiency can be improved, and the heat resistance and mechanical properties can be improved, so that the stability as a sealing member can be improved.

The rubber composition preferably further contains a processing aid and a lubricant. Examples of the processing aid (plasticizer) include process oils containing aliphatic hydrocarbons as a main component, for example, PW380 and PW220, which are photo-induced products, and they may be used alone or in combination. In particular, process oils are more preferable from the viewpoint that the process oils have a lower molecular weight than paraffins having similar chemical structures, and therefore, the process oils have unique effects that cannot be achieved when the paraffins are blended. As the lubricant, Diamid O-200, Diamid L-200, and the like, which are Japanese chemical products of fatty acid amides, can be used.

The amounts of the processing aid and the lubricant blended are preferably about 1 to 20 parts by weight, and more preferably about 3 to 15 parts by weight, respectively, based on 100 parts by weight of EBENB. By setting the above range, kneading processability becomes good, and oil bleeding and the like can be prevented.

In addition to the above components, a compounding agent generally used in the rubber industry, such as a plasticizer, an acid acceptor, and an antioxidant, may be appropriately added to the rubber composition as a rubber compounding agent, if necessary. The amount of the rubber compounding agent is preferably about 300 parts by weight or less with respect to 100 parts by weight of EBENB.

The rubber composition can be prepared by kneading various materials using a kneading machine such as a single-screw extruder, a twin-screw extruder, a roll, a banbury mixer, a kneader, or a high-shear mixer.

The rubber composition can be crosslinked by press-vulcanizing the rubber composition at a temperature of usually about 150 to 230 ℃ for about 0.5 to 30 minutes using an injection molding machine, a compression molding machine, or the like. After the primary vulcanization as described above, secondary vulcanization may be performed as necessary in order to ensure vulcanization to the inside of the vulcanizate. The secondary vulcanization can be usually carried out by heating in an oven at about 150 ℃ to 250 ℃ for about 0.5 to 24 hours.

The rubber molded article obtained by crosslinking and molding the rubber composition of the present invention has excellent low-temperature rubber characteristics particularly at-50 ℃ and can be used in a low-temperature environment (for example, about-40 ℃ to-60 ℃), and is suitably used as a rubber molded article. The value of TR10 measured by the low-temperature elastic recovery test defined in JIS K6261:2006 for such a rubber molded article is preferably-50 ℃ or lower.

Further, the rubber molded article of the present invention preferably has an appropriate hardness, and for example, if the rubber molded article is an O-ring, the type a durometer hardness (durometer hardness) specified in JIS K6253-1:2012, which corresponds to ISO 18517, is preferably 65 to 95.

Examples of the rubber molded article obtained include: sealing members for sealing low-temperature high-pressure gas, insulators, vibration insulators, sound insulators, and the like. Among them, the sealing material is suitable for use in a low-temperature environment and has excellent low-temperature sealing properties, and particularly suitable for use in high-pressure gas (e.g., high-pressure hydrogen) equipment.

The shape of the rubber molded article of the present invention is not particularly limited, and various shapes can be formed according to the use. Examples of the shape of the sealing member include an O-ring, a gasket, and a sheet.