JP2005187710A - Epihalohydrin rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epihalohydrin rubber composition which contains an environmentally safe antiaging agent and gives a crosslinked molded product excellent in aging resistance to heat. <P>SOLUTION: The epihalohydrin rubber composition comprises an epihalohydrin rubber (A), a crosslinking agent (B), an acid acceptor (C) and 0.1-30 pts.wt. of a phenothiazine compound (D) for 100 pts.wt. of the above epihalohydrin rubber (A). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an epihalohydrin rubber composition, and more particularly to an epihalohydrin rubber composition that provides a crosslinked molded article having excellent heat aging resistance and high environmental safety.

  Epihalohydrin rubber cross-linked molded products, in addition to excellent properties such as oil resistance, weather resistance, ozone resistance and low gas permeability, have been studied by studying compounding agents such as cross-linking agents, acid acceptors and retarders. Thus, compression set was improved, and heat resistance and heat aging resistance were improved by using an effective anti-aging agent. As a result, epihalohydrin rubber cross-linked molded products have come to be widely used in various rubber products such as hoses, tubes, diaphragms, gaskets, O-rings, tire inner liners, and wire coating materials, and particularly rubber products for automobiles. It became the material used suitably for.

In recent years, with the progress of efforts to prevent environmental pollution, the use and limitation of chemical substances suspected of environmental pollution are being controlled worldwide.
In Japan, the Environmental Pollutant Emission Control Improvement Promotion Law (PRTR Law) was promulgated, and nickel compounds such as nickel dibutyldithiocarbamate and nickel dimethyldithiocarbamate that are widely used as anti-aging agents for epihalohydrin rubber are carcinogenic by the PRTR law. It is designated as one of the specified first-class chemical substances with suspected sex. Therefore, an epihalohydrin rubber composition having high environmental safety that gives a crosslinked molded article having high heat aging resistance has been demanded.

  The objective of this invention is providing the epihalohydrin rubber composition with high environmental safety which can give the crosslinked molded object excellent in heat aging resistance.

As a result of diligent research to achieve the above object, the present inventors have found that a substance originally known as a polymerization inhibitor is a compound having an antiaging action capable of achieving the above object. The present invention has been completed based on this finding.
Thus, according to the present invention, the following (1) to (4) are provided.
1. Epihalohydrin rubber composition comprising 0.1-30 parts by weight of phenothiazine compound (D) per 100 parts by weight of epihalohydrin rubber (A), crosslinking agent (B), acid acceptor (C) and epihalohydrin rubber (A). Stuff.
2. The epihalohydrin rubber composition according to the above 1, further comprising a retarder (E).
3. Epihalohydrin rubber having a step of crosslinking the epihalohydrin rubber composition according to the above 1 or 2 with a molding machine and crosslinking at a temperature of 100 ° C. or more for 1 minute to 5 hours by heating at the time of molding or subsequent to molding. A method for producing a crosslinked molded article.
4). An epihalohydrin rubber cross-linked molded article obtained by molding and cross-linking the epihalohydrin rubber composition according to the above 1 or 2 with a molding machine.

  ADVANTAGE OF THE INVENTION According to this invention, the epihalohydrin rubber composition with high environmental safety which can give the crosslinked molded object excellent in heat aging resistance is provided.

  The epihalohydrin rubber composition of the present invention comprises an epihalohydrin rubber (A), a crosslinking agent (B), an acid acceptor (C), and 0.1 to 30 parts by weight of a phenothiazine compound (D) per 100 parts by weight of the epihalohydrin rubber (A). ).

The epihalohydrin rubber (A) used in the present invention may be referred to as an epihalohydrin monomer [hereinafter referred to as “monomer (a1)”. Or a ring-opening copolymer of the monomer (a1) and a monomer copolymerizable therewith.
Examples of the monomer (a1) include epichlorohydrin, epibromohydrin, 2-methylepichlorohydrin, and the like, among which epichlorohydrin is preferable.
The content of the monomer (a1) unit relative to all monomer units constituting the epihalohydrin rubber is not particularly limited, but is preferably 20 to 100 mol%, more preferably 25 to 90 mol%, and particularly preferably 30 to 85 mol. %. If the monomer (a1) unit content is too small, the hygroscopicity of the cross-linked molded product may be high, and if it is too large, the cold resistance of the cross-linked molded product may be reduced.

  Examples of the monomer copolymerizable with the monomer (a1) include an oxirane monomer, and among them, an alkylene oxide [hereinafter referred to as “monomer (a2)”]. ] Is preferable. Specific examples of the monomer (a2) include ethylene oxide, propylene oxide, 1,2-epoxybutane, 2,3-epoxybutane, 1,2-epoxy-4-chloropentane, 1,2-epoxyhexane, , 2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, 1,2-epoxyoctadecane, 1,2-epoxyeicosane, 1,2-epoxyisobutane, 2, , 3-epoxyisobutane or the like; linear alkylene oxide such as 1,2-epoxycyclopentane, 1,2-epoxycyclohexane, 1,2-epoxycyclododecane; Among these, linear alkylene oxide is preferable, and ethylene oxide or propylene oxide is particularly preferable. The alkylene oxide may be one in which part of hydrogen is substituted with halogen (excluding epihalohydrin).

  The content of the monomer (a2) unit with respect to all the monomer units constituting the epihalohydrin rubber is not particularly limited, but is preferably 0 to 80 mol%, more preferably 10 to 75 mol%, particularly preferably 15 to 70 mol. %. If the monomer (a2) unit content is too large, the crosslinked molded article tends to foam during molding, and the hygroscopicity of the crosslinked molded article may increase.

  The (A) component epihalohydrin rubber contains a monomer (a3) having a crosslinkable functional group as a copolymerization component as at least a part of the oxirane monomer copolymerizable with the monomer (a1). Also good. As the monomer (a3), compounds having a glycidyl ether group such as vinyl glycidyl ether, allyl glycidyl ether, o-allylphenyl glycidyl ether; glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl-4-heptenoate, glycidyl sol Compounds having a glycidyl ester group such as beeth, glycidyl linoleate, glycidyl ester of 3-cyclohexenecarboxylic acid, glycidyl ester of 4-methyl-3-cyclohexenecarboxylic acid, glycidyl-4-methyl-3-pentenoate; And epoxy group-containing unsaturated hydrocarbons such as epoxy-1-butene, 1,2-epoxy-3-pentene, and 1,2-epoxy-5,9-cyclododecadiene. Among these, when allyl glycidyl ether is used, since a crosslinked molded object is excellent in ozone resistance, it is preferable.

  The content of the monomer (a3) unit in the epihalohydrin rubber (A) is not particularly limited, but is preferably 15 mol% or less, more preferably 10 mol% or less. If the monomer (a3) unit content is too large, the elongation at break of the crosslinked molded product may be too low.

The Mooney viscosity ML _{1 + 4} (100 ° C.) of the epihalohydrin rubber (A) is usually 30 to 160, preferably 40 to 120. If the Mooney viscosity is too low or too high, the kneading processability with the compounding agent is not preferable.

The crosslinking agent (B) contained in the composition of the present invention is not particularly limited as long as it is generally used for crosslinking of epihalohydrin rubbers. Sulfur, sulfur donor, diazine thiol compound, triazine thiol compound, thiadiazole compound Thiourea compounds, organic peroxides, polyol compounds, mercaptoquinoxaline compounds, and the like. Among these, a diazine thiol compound and a triazine thiol compound are preferable from the viewpoint of heat aging resistance.
Examples of diazine thiol compounds include 1,2-diazine-3,6-dithiol, 1,3-diazine-2,5-dithiol, 1,4-diazine-2,3-dithiol, 6-methylamino- Examples thereof include 1,4-diazine-2,3-dithiol, S, S-6-methylquinoxaline-2,3-diyldithiocarbonate, and the like is used alone or in combination of two or more.
Examples of the triazine thiol compound include 1,3,5-triazine dithiol and derivatives thereof. The derivatives of 1,3,5-triazinedithiol include 1,3,5-triazinetrithiol, 6-anilino-1,3,5-triazine-2,4-dithiol, 6-methylamino-1,3, 5-triazine-2,4-dithiol, 6-dimethylamino-1,3,5-triazine-2,4-dithiol, 6-ethylamino-1,3,5-triazine-2,4-dithiol, 6- Diethylamino-1,3,5-triazine-2,4-dithiol, 6-propylamino-1,3,5-triazine-2,4-dithiol, 6-dipropylamino-1,3,5-triazine-2 , 4-dithiol, 6-butylamino-1,3,5-triazine-2,4-dithiol, 6-dibutylamino-1,3,5-triazine-2,4-dithiol, 6-hexylurea No-1,3,5-triazine-2,4-dithiol, 6-octylamino-1,3,5-triazine-2,4-dithiol, 6-decylamino-1,3,5-triazine-2,4 -Dithiol etc. can be mentioned, 1 type is used individually or in combination of 2 or more types.

  What is necessary is just to determine content of a crosslinking agent (B) by the characteristic of each crosslinking agent. For example, the content in the case of using a diazine thiol compound or a triazine thiol compound as a crosslinking agent is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight per 100 parts by weight of the epihalohydrin rubber (A). Part. If the content of the crosslinking agent (B) is too small, the crosslinking rate and the crosslinking density may be lowered. If the content is too large, the storage stability of the rubber composition is lowered or the crosslinking density becomes too high. May become brittle.

  The composition of the present invention contains an acid acceptor (C) in order to capture hydrogen halide such as hydrogen chloride by-produced during the crosslinking reaction. The acid acceptor (C) is not particularly limited as long as it is generally used as an acid acceptor during molding and crosslinking of epihalohydrin rubber. Examples of such acid acceptors include magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, magnesium carbonate, barium carbonate, calcium carbonate, calcium borate, zinc stearate, calcium phthalate, calcium phosphite , Zinc oxide, calcium silicate, magnesium silicate, magnesium borate, magnesium metaborate, calcium metaborate, barium metaborate and other group 2 metal oxides, hydroxides, carbonates, carboxylates , Silicate, borate, phosphite, metaborate, etc .; periodic table of tin oxide, basic tin carbonate, tin stearate, basic tin phosphite, basic tin sulfite, silicon oxide, silicon stearate, etc. Group 14 metal oxides, basic carbonates, basic carboxylates, basic phosphites, bases Such as sulfites; hydrotalcite; aluminum hydroxide gel compound; and the like. Of these, magnesium oxide, calcium oxide, calcium carbonate, barium metaborate, magnesium silicate (especially amorphous) are preferred, hydrotalcites, and aluminum hydroxide gel compounds in terms of easy adjustment of the crosslinking rate. (The aluminum hydroxide gel compound is particularly preferably that described in JP-A No. 2002-179845).

  Since there are more preferable acid acceptors depending on the crosslinking agent, it is preferable to use them in combination. For example, magnesium oxide and calcium carbonate are used for triazine thiol compounds, diazine thiol compounds [Daisonet XL-21: S, S-methylquinoxaline-2,3-diyldithiocarbonate (manufactured by Daiso Corporation), etc.] Calcium carbonate and calcium hydroxide for polythiol compounds, and barium carbonate for polythiol compounds as main components. Magnesium silicate (amorphous), hydrotalcite, aluminum hydroxide gel compound, etc. Is preferably used in combination.

  The content of the acid acceptor (C) is preferably 0.5 to 30 parts by weight, more preferably 1 to 25 parts by weight per 100 parts by weight of the epihalohydrin rubber (A). If the amount of the acid acceptor is too small, the crosslinking density may be decreased or the heat aging resistance may be decreased. If the amount is too large, the storage stability of the rubber composition may be decreased, or the tensile strength and elongation of the crosslinked molded body may be decreased. It may become insufficient.

  The epihalohydrin rubber composition of the present invention contains a phenothiazine compound (D). Although a phenothiazine compound (D) will not be specifically limited if it is a compound which has a phenothiazine skeleton, The compound shown by following General formula (1) is preferable.

Here, R1 and R2 represent hydrogen or an alkyl group having 1 to 20 carbon atoms. The phenothiazine compound of the general formula (1) is highly safe against environmental pollution and is not a designated chemical substance of the PRTR method. Specific examples include phenothiazine in which R1 and R2 are hydrogen, and 3,7-dioctylphenothiazine in which R1 and R2 are octyl groups.
The content of the phenothiazine compound (D) in the epihalohydrin rubber composition of the present invention is 0.1 to 30 parts by weight, preferably 0.2 to 10 parts by weight, more preferably 0.8 parts by weight per 100 parts by weight of the epihalohydrin rubber (A). 5 to 5 parts by weight. If the content of the phenothiazine compound (D) is too small, the heat aging resistance of the crosslinked molded article may be reduced. Conversely, if the content is too large, the mechanical strength of the crosslinked molded article may be reduced.

The epihalohydrin rubber composition of the present invention preferably further contains a retarder (E). The retarder (E) has an action of preventing partial crosslinking from occurring in the storage stage until the epihalohydrin rubber composition is crosslinked. The retarder (E) is not limited as long as it is generally used in the processing of epihalohydrin rubber, but when a diazine thiol compound or a triazine thiol compound is used as the crosslinking agent (B), a thioimide retarder ( E1) or sulfonamide retarders (E2) are preferred. These are both compounds having a molecular structure = NS-.
The thioimide retarder (E1) is a compound having a partial structure of the following formula (2) in the molecule.

It is preferable that the aralkyl group which has a C1-C12 alkyl group, a cycloalkyl group, an aryl group, or a C1-C8 alkyl group couple | bonds with the sulfur atom of General formula (2). Although the dibasic acid which is the origin of the acyl group is not limited, a dibasic acid having 4 to 10 carbon atoms is preferable.
Examples of the thioimide retarder include N-2-ethylhexylthiophthalimide, N-cyclohexylthiophthalimide, N-cyclohexylthiomaleimide, N-4-t-butylphenylthiosuccinimide, and the like. These are used together. Among these, N-cyclohexylthiophthalimide is preferable because it is easily available.

  Examples of the sulfonamide retarder (E2) include N-phenyl-N-trichloromethylthiobenzenesulfonamide, N-isopropylthio-N-cyclohexylbenzothiazole-2-sulfonamide, and the like. The agent “Vulkalent E / C, sulfonamide derivative” is also included in (E2). These may be used alone or in combination of two or more. Of these, N-phenyl-N-trichloromethylthiobenzenesulfonamide is preferred.

  The content of the retarder (E) is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, particularly preferably 0.5 to 3 parts by weight per 100 parts by weight of the epihalohydrin rubber (A). Part. If the content of the component (E) is too small, the induction period necessary for crosslinking of the epihalohydrin rubber composition cannot be obtained, and scorching is likely to occur. Conversely, if the content is too large, the crosslinking rate at the time of crosslinking is slowed. May occur.

  In the epihalohydrin rubber composition of the present invention, a crosslinking accelerator, a reinforcing material, a filler, a light stabilizer, a processing aid, a plasticizer, a lubricant, a pressure-sensitive adhesive, as long as the object of the present invention is not impaired as necessary. You may mix | blend additives, such as a lubricant, a flame retardant, an antifungal agent, an antistatic agent, and a coloring agent.

  Moreover, you may further mix | blend rubber | gum other than epihalohydrin rubber, an elastomer, resin, etc. with the said epihalohydrin rubber composition as needed. For example, rubber such as natural rubber, acrylic rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber; olefin elastomer, styrene elastomer, vinyl chloride elastomer, polyester elastomer, polyamide elastomer, polyurethane Elastomers such as polyelastomers and polysiloxane elastomers; polyolefin resins, polystyrene resins, polyacrylic resins, polyphenylene ether resins, polyester resins, polycarbonate resins, polyamide resins, etc. it can.

  For the preparation of the epihalohydrin rubber composition, a mixer such as a roll, a Banbury mixer, or a screw mixer can be appropriately employed. The blending order of the rubber component and other compounding agents is not particularly limited. First, a component that does not easily react or decompose with other components due to heat is sufficiently mixed with a Banbury mixer, etc., and then reacted with other components with heat. It is preferable to adopt a procedure in which components that are easily decomposed or decomposed are mixed in a short time at a temperature that does not cause reaction or decomposition with a roll or the like.

The epihalohydrin rubber composition of the present invention can be molded by a molding machine and formed into a crosslinked molded body by heating at the time of molding or by heating subsequent to molding. The heating is preferably performed at 100 ° C. or higher for 1 minute to 5 hours. That is, in the method for producing a crosslinked epihalohydrin rubber molded product of the present invention, the epihalohydrin rubber composition of the present invention is molded with a molding machine and heated at 100 ° C. or higher for 1 minute by heating at the time of molding or subsequent to molding. It has the process of bridge | crosslinking over -5 hours, It is characterized by the above-mentioned.
When the epihalohydrin rubber composition is cross-linked, the step is a primary cross-linking step, and if necessary, the primary cross-linked molded body obtained in the primary cross-linking step is heated at 100 to 220 ° C. for 0.5 to 48 hours. A step of secondary crosslinking may be further added.

  The conditions for secondary cross-linking performed on the primary cross-linked molded article as necessary are that the heating temperature is 100 to 220 ° C, preferably 130 to 210 ° C, more preferably 150 to 180 ° C, and the heating time is 0.5. 48 hours, preferably 0.7 to 24 hours, more preferably 1 to 12 hours. By performing the secondary crosslinking, the compression set of the crosslinked rubber becomes smaller. If the temperature of secondary crosslinking is too low, bloom may occur, and conversely, if it is too high, the surface of the resulting crosslinked molded article may become sticky.

  The cross-linked molded article of the epihalohydrin rubber composition of the present invention uses a highly environmentally safe anti-aging agent and is extremely excellent in heat aging resistance. It is useful as a sealing material, cushioning / protection material, electric wire covering material, belts, hoses, sheets, rolls, etc. in a wide range of applications such as equipment and architecture.

The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following, [part] and [%] are based on weight unless otherwise specified.
The test method was as follows.
(1) Mooney scorch test A Mooney scorch test was prepared by preparing an epichlorohydrin rubber composition and placing it in an atmosphere (environment I) at a temperature of 23 ° C and a relative humidity of 55% for 24 hours, and a temperature of 40 ° C and a relative humidity of 80%. For an atmosphere (environment II) for 24 hours, in accordance with JIS K6300, Mooney scorch time (t5) and Mooney viscosity [ML _{1 + 4} (100 ° C.)] at 125 ° C. using L rotor (Vmin) Was measured.
Further, the percentage of t5 in environment II to t5 in environment I was determined as the t5 retention rate. It shows that the storage stability with respect to temperature is so large that this value is large.

(2) Cross-linking test The cross-linking test was conducted for the epichlorohydrin rubber composition placed in environment I of (1) above for 24 hours in accordance with JIS K6300 using a curast meter (manufactured by Nichigo Corporation) at 160 ° C maximum torque (MH ) And minimum torque (ML).

(3) Normal physical properties of the crosslinked molded article The epichlorohydrin rubber composition was molded by pressing at 180 ° C. for 20 minutes and subjected to primary crosslinking to obtain a sheet of 15 cm in length × 15 cm in width × 2 mm in thickness. JIS No. 3 dumbbell-shaped test pieces were produced after a second cross-linking after a while. Using these four test pieces, the tensile strength, 100% tensile stress, and elongation at break (elongation) were measured in accordance with JIS K6251, and the hardness test was measured in accordance with JIS K6253, and average values were obtained to obtain normal physical properties.

(4) Thermal aging test 12 specimens / samples prepared in the same manner as in (3) above were placed in an oven at 135 ° C. for 72 hours, 120 hours and 168 hours, and then each 4 sheets were taken out and (3) Tensile strength, 100% tensile stress, elongation, and hardness were measured in the same manner as above, and the rate of change from the normal physical properties in (3) above was determined for each average value.

(5) Compression set The compression set was determined by placing the sheet prepared in the same manner as in (3) above in a 160 ° C. oven for 30 minutes and then performing secondary crosslinking, and then setting the compression set to 135 ° C. according to JIS K6262. The measurement was performed under the condition of 72 hours.

Example 1
In a Banbury mixer, 100 parts of epichlorohydrin rubber [epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer; made by Nippon Zeon Co., Ltd., Gechron 3105 (chlorine content center value 27.5%, Mooney viscosity 76.5)], sorbitan as a processing aid Surface with monostearate (Splendor R300, manufactured by Kao Corporation) and reinforcing carbon black (Asahi 60, manufactured by Asahi Carbon Co., Ltd.) and calcium carbonate (Shiraka Hana CC, Shiraishi Kogyo Co., Ltd., approximately 2% calcium stearate 5 parts) was kneaded at 50 ° C. with a Banbury mixer. Next, 0.9 parts of the crosslinking agent 1,3,5-triazine trithiol, 3 parts of magnesium oxide (MgO100, manufactured by Kyowa Chemical Co., Ltd.) and the retarder N-cyclohexylthiophthalimide (retarder) were added to the kneaded product. 1 part of CTP (manufactured by Toray Industries, Inc.) and 1 part of anti-aging agent 3,7-dioctylphenothiazine (prototype manufactured by Seiko Chemical Co., Ltd.) were added and kneaded using a roll to prepare an epichlorohydrin rubber composition. Table 1 shows the results of testing and evaluating the scorch test, the crosslinking test, the normal physical properties of the crosslinked molded article, the heat aging test and the compression set using this rubber composition.

Examples 2-4, Comparative Examples 1-2
An epichlorohydrin rubber composition was prepared in the same manner as in Example 1 with the components and parts shown in Table 1, and tested and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Note * 1: Aluminum hydroxide gel compound (AD200P, manufactured by Tomita Pharmaceutical)
* 2: Phenothiazine (Seiko Chemical Co., Ltd.)
* 3: Nickel dibutylcarbamate (NOCRACK NBC, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

As Table 1 shows, the comparison between Examples 1 and 2 and Comparative Example 1 in which the type and content of the crosslinking agent and acid acceptor were the same and the anti-aging agent was changed, and Examples 3 and 4 From comparison with Comparative Example 2, the epichlorohydrin rubber composition of the present invention using a highly environmentally safe phenothiazine compound as an anti-aging agent is a change in tensile strength, 100% tensile stress and hardness in the heat aging test. It was confirmed that a crosslinked molded product having a low rate and excellent heat aging resistance, and not inferior in scorch test (storage stability), cross-linking test and normal physical properties was obtained.

Claims (4)

  Epihalohydrin rubber composition comprising 0.1-30 parts by weight of phenothiazine compound (D) per 100 parts by weight of epihalohydrin rubber (A), crosslinking agent (B), acid acceptor (C) and epihalohydrin rubber (A). Stuff.   The epihalohydrin rubber composition according to claim 1, further comprising a retarder (E).   An epihalohydrin comprising a step of forming the epihalohydrin rubber composition according to claim 1 or 2 with a molding machine, and performing crosslinking at 100 ° C or higher for 1 minute to 5 hours by heating at the time of molding or subsequent to molding. A method for producing a rubber cross-linked molded article. An epihalohydrin rubber crosslinked molded article obtained by molding and crosslinking the epihalohydrin rubber composition according to claim 1 or 2.