JPH0430963B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a new acrylic copolymer into which units bonded with vinyl group-containing organosilicon groups are introduced, and in particular, the vulcanization properties with peroxides are significantly improved. The purpose is to provide an acrylic copolymer. (Conventional technology) Acrylic rubber has traditionally been known as a rubber that has heat resistance, oil resistance, and ozone resistance, and has been used as a sealing material,
It is used in fields such as gaskets and hose materials that take advantage of its properties such as heat resistance, aging resistance, and oil resistance. Currently, acrylic rubber is made by copolymerizing acrylic acid ester as a main component with a small amount of active chlorine-containing monomers such as 2-chlorovinyl ether and monochlorovinyl acetate, or epoxy-containing monomers such as glycidyl methacrylate and allyl glycidyl ether. has been put into practical use. However, for this type of acrylic rubber, (a) polyamine-based or sulfur-based vulcanizing materials are used to complete the vulcanization, and press vulcanization is performed at a temperature of about 170 to 180°C for several minutes. Then, it is necessary to carry out post-vulcanization for several hours, and the vulcanization rate is significantly slower than that of other common rubbers. c) Products using polyamine-based vulcanizing agents have drawbacks such as being unsuitable for pharmaceutical and food-related uses due to toxicity. In order to improve these drawbacks, attempts have been made to introduce unsaturated bonding groups into the side chains. Methods of vulcanization using sulfur or peroxide are known, but vulcanization is very slow and roll workability is poor, so that no practical method has been obtained. Recently, a method has been proposed in which acrylic ester and norbornene derivatives are copolymerized and sulfur vulcanization or peroxide vulcanization is performed, but although considerable improvements have been made in sulfur vulcanization, peroxide In terms of vulcanization, the vulcanization rate is still slow, making it difficult to put it into practical use. (Structure of the Invention) In order to overcome such conventional drawbacks, the present inventors
As a result of intensive research, the present invention was completed. That is, the present invention provides the following: (a) General formula CH ₂ =C(R ¹ )(COOR ² )...() (R ¹ in the formula is a hydrogen atom or a methyl group, R ²
(b) 60 to 99.99 parts by weight of an acrylic monomer represented by an alkyl group having 1 to 8 carbon atoms or an alkyl group substituted with an alkoxy group; [In the formula, R ³ is a monovalent organic group having a polymerizable olefin bond (excluding a vinyl group when p = 0), R ⁴ and R ⁵ are a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R ⁶ is an unsubstituted or substituted monovalent hydrocarbon group, a hydrogen atom, a hydroxyl group, or a hydrolyzable group other than a halogen atom, p is 0-10, q is 0-50, a is 0-2, b is 1-
3 and a+b=3, respectively. ] 0.01 to 10 parts by weight of a polymerizable organosilicon monomer represented by (c) 0 to 30 parts by weight of other ethylenically unsaturated group-containing monomers are subjected to a copolymerization reaction using a radical polymerization initiator. The present invention relates to a method for producing an acrylic copolymer having a vinyl group-containing organosilicon group. The acrylic copolymer obtained by the method of the present invention has remarkable vulcanization properties with peroxides, good processability, and excellent physical properties.
In particular, regarding the vulcanization characteristics of peroxides, due to the reaction specificity of vinyl groups bonded to silicon atoms, vulcanization progresses rapidly after an induction period of several minutes and is completed in a short time. Pressure hot air vulcanization is possible;
It has the advantage of not requiring complicated operations such as post-vulcanization. The present invention will be explained in detail below. As mentioned above, the acrylic copolymer obtained by the method of the present invention essentially contains monomer components (a) and (b), and optionally copolymerizes monomer component (c). In particular, it is characterized by the introduction of a unit bonded to an organosilicon group having a vinyl group directly bonded to a silicon atom. The reactivity of this vinyl group directly bonded to a silicon atom is significantly different from that of general vinyl monomers.
As disclosed in Publication No. 55-41704, even if a mixture of an organopolysiloxane having a vinyl group directly bonded to a silicon atom and a general vinyl monomer (olefinic monomer) is polymerized with a free radical polymerization initiator. Although the organopolysiloxane has a vinyl group, it does not undergo any polymerization reaction or grafting reaction, only the vinyl monomer undergoes a polymerization reaction, and a mixture of the polymer obtained by this polymerization and the organopolysiloxane is obtained. As is clear from the fact that only the following is obtained, in normal radical polymerization, the vinyl group directly bonded to the silicon atom is preserved as it is. On the other hand, when the unsaturated group bonded to the silicon atom is a 3-(acryloxy)propyl group, 3-(methacryloxy)propyl group, 4-vinylphenyl group, methacryloxymethylene group, etc.
These are easily copolymerized by normal radical polymerization like general ethylenically unsaturated monomers. In the present invention, a mixture consisting of a predetermined ratio of component (a), component (b), and component (c) used as necessary is prepared by using a commonly used radical polymerization initiator.
The desired acrylic copolymer is produced by carrying out a polymerization reaction using methods such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization. As the main component (a), an acrylic monomer represented by the above general formula (), that is, an acrylic ester or a methacrylic ester is used. R ¹ in the formula is a hydrogen atom or a methyl group,
In addition, R ² represents an alkyl group having 1 to 8 carbon atoms or an alkyl group substituted with an alkoxy group;
Specific examples of R ² include methyl group, ethyl group,
Examples include propyl group, n-butyl group, i-butyl group, pentyl group, hexyl group, 2-ethylhexyl group, octyl group, methoxyethyl group, and ethoxyethyl group. In addition, ester residue (R ² )
As the chain length of R2 increases, a copolymer with high rebound resilience is obtained, while as the chain length of ^R2 decreases, the tensile strength,
A copolymer with improved oil resistance and heat resistance can be obtained. Next, as component (b), a polymerizable organosilicon monomer represented by the above general formula () is used. Examples of R ³ in the formula include monovalent organic groups having a polymerizable olefin bond, such as an acryloxy group, a methacryloxy group, and a 4-vinylphenyl group. R ⁴ and R ⁵ are hydrogen atoms, methyl groups,
Alkyl groups such as ethyl, propyl, and butyl groups, aryl groups such as phenyl and tolyl groups, cycloalkyl groups such as cyclohexyl, or some or all of the hydrogen atoms bonded to the carbon atoms of these groups are halogenated. Examples include monovalent hydrocarbon groups substituted with atoms, cyano groups, and the like. Examples of R ⁶ include hydrogen atoms, hydroxyl groups, hydrolyzable groups other than halogen atoms, and unsubstituted or substituted monovalent hydrocarbon groups exemplified by R ⁴ and R ⁵ . p, q
and a and b are as described above. like this
Specific examples of polymerizable organosilicon compounds corresponding to component (b) are as follows. However, in the following description, Me represents a methyl group and Ph represents a phenyl group. By introducing into the acrylic polymer a unit in which the above-mentioned vinyl group-containing organosilicon group is bonded, the vulcanization properties with organic peroxides are significantly improved, and atmospheric pressure hot air vulcanization can proceed easily. and the vulcanization properties are exhibited without being inhibited even when a silicic acid filler is blended. The ratio of component (B) used is 0.01 to 10 parts by weight (especially 0.1 to 5 parts by weight) of component (B) to 60 to 99.99 parts by weight of component (B).
If the amount is less than 0.01 parts by weight, the vulcanization rate will be slow, and if it is more than 10 parts by weight, the vulcanization will progress too much and the physical properties of the rubber will deteriorate. Other ethylenically unsaturated group-containing monomers as component (c) are used as necessary, and include styrene, vinyltoluene, α-methylstyrene, vinylnaphthalene, acrylonitrile,
Examples include methacrylonitrile, acrylamide, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, and propylene. When using these monomer components, the amount of component (c) should be 30 parts by weight or less compared to 60 to 99.99 parts by weight of component (a), and if more than 30 parts by weight is used, the acrylic rubber This is not preferable because the original physical properties are impaired. Radical polymerization initiators used to carry out the copolymerization reaction include ammonium persulfate,
Water-soluble types such as potassium persulfate and hydrogen peroxide, and oil-soluble types with a 10-hour half-life of 80°C or less such as benzoyl peroxide, lauryl peroxide, azobisisobutyronitrile, and diisopropyl peroxydicarbonate. preferable. When copolymerizing at a low temperature of 40°C or lower, it is preferable to use a redox catalyst in combination with a reducing agent.For water-soluble types, it is preferable to use a redox catalyst in combination with ferrous sulfate, and for oil-soluble types, use benzoyl peroxide/N,N.
-dimethylaniline combinations are preferred. Preferred polymerization temperatures range from 0 to 80°C. The obtained copolymer is a rubber that has heat resistance, oil resistance, and ozone resistance, and can be used in applications that take advantage of its properties, such as various sealing materials, gaskets, and hose materials. Next, specific examples will be given. However, in the following description, all parts simply refer to parts by weight. Example 1 Water was added to a closed reactor equipped with a stirrer and replaced with nitrogen.
After charging 200 parts and 2 parts of sodium lauryl sulfate and adjusting the temperature inside the reactor to 30°C, 0.1 part of ammonium persulfate, 0.1 part of sodium acid sulfite and 0.001 part of ferrous sulfate were added, and then the following monomer mixture acrylic was added. 99 parts of ethyl acid 1 part of S-5 (listed above) was added over a period of 3 hours. Stirring was continued for another hour while maintaining the inside of the reactor at 30°C to complete the reaction. The milky white emulsion obtained by the above emulsion polymerization was salted with CaCl ₂ aqueous solution, washed with water and dried.
A copolymerization product was obtained with a yield of 99.5%. When the Mooney viscosity [ML ₁₊₄ (100°C)] of this copolymer was measured, the value was 51. On the other hand, the above copolymer was uniformly kneaded with two rolls at room temperature using the following formulation (however, only the peroxide was added later), and then kneaded at 110°C.
The peroxide paste was kneaded for 30 minutes with a roll to remove water in the silica, and after cooling, the peroxide paste was mixed uniformly to obtain a kneaded sheet. (Composition) Copolymer 100 parts Finely powdered silica 40 parts Stearic acid 1 part Zinc oxide 5 parts 50% 2,4-dichlorobenzoyl peroxide paste 2 parts This kneaded sheet was heated in a hot oven at 250°C for 3 minutes. When the rubber sheet was vulcanized, a vulcanized rubber sheet was obtained without foaming. Various physical properties of this rubber sheet were measured according to JIS K 6301. The results were as shown in Table 1.

[Table] Example 2 Water was added to a closed reactor equipped with a stirrer and replaced with nitrogen.
230 parts and Metrose 60SH-4000 (manufactured by Shin-Etsu Chemical, hydroxypropyl methylcellulose)
After charging 0.04 parts, the following monomer mixture: 85.5 parts of butyl acrylate, 12.5 parts of acrylonitrile, 2.0 parts of S-2 (listed above) was added and dispersed. Polymerization was initiated by adding 1.0 part of diisopropyl peroxydicarbonate (manufactured by Nippon Steel Co., Ltd.). The reaction was carried out for 3 hours while maintaining the inside of the reactor at 45°C, and stirring was continued for an additional hour at 50°C to complete the reaction. The obtained slurry was excessively dehydrated and then dried to obtain a spherical rubber copolymer having a diameter of 0.5 to 2 mm with a yield of 96%. Mooney viscosity of this [ML ₁₊₄ (100
℃)] was 55. This copolymer was uniformly kneaded with two rolls at room temperature according to the following formulation, and the resulting kneaded sheet was press-vulcanized at 170°C for 15 minutes and its physical properties were measured. The results were as shown in Table 2 below. (Composition) Copolymer 100 parts FEF carbon black 50 parts stearic acid 1 part zinc oxide 5 parts 65% t-butylcumyl peroxide paste
2nd part

[Table] Examples 3 to 8 By changing the monomer composition (as shown in Table 3)
Rubber copolymers obtained by copolymerization in the same manner as in Example 1 were used in Examples 3 to 5 and Examples 6 to 8.
A kneaded sheet was prepared using the following formulation and vulcanized. Good vulcanized sheets with no foaming were obtained in all cases, and the physical properties were as shown in Table 3. (Combination prescription)

[Table] Peroxide paste
(Vulcanization conditions) Examples 3 to 5: The kneaded sheets were press-vulcanized at 170°C for 15 minutes. Examples 6 to 8: The kneaded sheets were subjected to hot air vulcanization at normal pressure at 250°C for 3 minutes.

[Table] Comparative Examples 1 and 2 Ethyl acrylate, ethylidene norbornene and allyl glycidyl ether were emulsion copolymerized according to Example 1 with the copolymerization composition shown in Table 4.
The obtained rubber copolymer was roll-kneaded according to the following formulation. (Combination prescription)

[Table] Oxide base
The obtained kneaded sheet was press-vulcanized at 170°C for 15 minutes, and this material was then vulcanized in a gear oven.
When various physical properties were measured for the product vulcanized at 170°C for 3 hours, the results shown in Table 4 were obtained. Although the kneaded sheet was vulcanized at 250°C for 3 minutes under normal pressure, only semi-cured sheets with significant foaming were obtained in both Comparative Examples 1 and 2.
In this case, 2 parts of 50% 2,4-diclobenzoyl peroxide paste was used as the vulcanizing agent).

【table】

[Table] Next, Examples 1, 3, 6, and Comparative Example 1,
JSR vulcanization curve at 170℃ for compounding recipe 2
When measured with a cuylastometer type,
Each was as shown in Figure 1. As is clear from the above results, conventional acrylic rubbers have a slow vulcanization rate and require a long post-vulcanization after normal press vulcanization to obtain desired physical properties. On the other hand, the rubber copolymer produced by the method of the present invention has a fast vulcanization rate, particularly a fast initial rise, and vulcanization is completed in a short time, so hot air vulcanization at normal pressure is possible. Its industrial advantages are enormous.

[Brief explanation of drawings]

FIG. 1 shows vulcanization curves at 170° C. for the formulations of Examples 1, 3, and 6 and Comparative Examples 1 and 2.

Claims (1)

[Claims] 1 (a) General formula CH ₂ =C(R ¹ )(COOR ² ) (R ¹ in the formula is a hydrogen atom or a methyl group, R ²
(b) 60 to 99.99 parts by weight of an acrylic monomer represented by an alkyl group having 1 to 8 carbon atoms or an alkyl group substituted with an alkoxy group; [In the formula, R ³ is a monovalent organic group having a polymerizable olefin bond (excluding a vinyl group when p = 0), R ⁴ and R ⁵ are a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R ⁶ is an unsubstituted or substituted monovalent hydrocarbon group, a hydrogen atom, a hydroxyl group, or a hydrolyzable group other than a halogen atom, p is 0-10, q is 0-50, a is 0-2, b is 1-
3 and a+b=3, respectively. 0.01 to 10 parts by weight of a polymerizable organosilicon monomer represented by ], and (c) 0 to 10 parts by weight of other ethylenically unsaturated group-containing monomers.
A method for producing an acrylic copolymer having a vinyl group-containing organosilicon group, which comprises copolymerizing 30 parts by weight of the following using a radical polymerization initiator.