JP3402559B2 - Chloroprene polymer composition and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chloroprene polymer composition having excellent ozone resistance, particularly long cutting life, and excellent injection moldability, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Chloroprene polymers have a good balance of physical properties such as general rubber physical properties, weather resistance, heat resistance, chemical resistance, etc., so that they can be used in a wide range of fields such as general industrial rubber products, automobile parts and adhesives. It is used. However, in recent years, the environment in which rubber products are used has become harsh,
It has become difficult to cope with conventional chloroprene-based polymers.

One of such required properties is ozone resistance. As a method for improving the ozone resistance, a method of adding an antioxidant is generally used in chloroprene polymers and is widely used. There is.

However, the method of adding an antioxidant may cause problems such as burning of an unvulcanized product, blooming of the antioxidant, and reduction in tensile strength of the vulcanized product. Not only was it difficult to select the type and amount used, but the effect of improving ozone resistance was not sufficient.

On the other hand, the present inventors have found that a chloroprene-based polymer containing an acrylic polymer is excellent in ozone resistance, in particular, in respect of crack generation, but it has injection moldability and extended cutting life. There was room for further improvement in the effect.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above drawbacks, and provides a chloroprene polymer composition having a significantly improved ozone resistance and an improved injection moldability, and a method for producing the same. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems is based on a chloroprene polymer containing (a) ethyl acrylate, (b) n-butyl acrylate and (c) an epoxy group-containing ethylenic monomer. It is intended to obtain a chloroprene polymer composition containing an acrylic copolymer which is a copolymer with a saturated compound. Further, the present invention is an acrylic copolymer which is a copolymer of a chloroprene polymer latex, (a) ethyl acrylate, (b) n-butyl acrylate and (c) an ethylenically unsaturated compound having an epoxy group. The present invention provides a method for producing a chloroprene polymer composition, which is obtained by mixing an emulsion.

The chloroprene polymer in the present invention means a homopolymer of 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene) or one or more of chloroprene and a monomer copolymerizable with chloroprene. It is a copolymer obtained by this.

Examples of the monomer copolymerizable with chloroprene in the present invention include 2,3-dichloro-1,3-
Examples thereof include butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, sulfur, styrene, acrylonitrile, acrylic acid and its ester, methacrylic acid and its ester, and two or more kinds may be used as necessary. .

In the present invention, chloroprene alone or a monomer mixture containing chloroprene and a monomer copolymerizable therewith can be polymerized by any known method, but radical polymerization is carried out in an aqueous emulsion. The method is the most common and suitable.

The emulsifier used in the aqueous emulsion polymerization is not particularly limited, and is generally an emulsifier used in the emulsion polymerization of chloroprene, for example, an anionic emulsifier such as a rosin acid salt, a fatty acid salt or an alkylbenzene sulfonate, or an alkyl. Nonionic emulsifiers such as polyethylene glycol and polyvinyl alcohol, and cationic emulsifiers such as quaternary ammonium salts can be used. However, anionic emulsifiers such as rosin acid salts and fatty acid salts are preferable.

The polymerization temperature in the present invention is not particularly limited, but is preferably in the range of 0 to 55 ° C. When the polymerization temperature is lower than 0 ° C, solidification of water becomes a problem, and at a temperature higher than 55 ° C, pressure equipment is required due to the vapor pressure of chloroprene.

The control of the molecular weight of the chloroprene polymer is
Usually, a chain transfer agent is used, but as the chain transfer agent, generally known, for example, alkyl mercaptans such as dodecyl mercaptan, xanthogen disulfides such as diethylxanthogen disulfide, halogenated hydrocarbons such as iodoform, etc. Can be used.

The polymerization initiator may be an organic or inorganic peroxide used in a usual chloroprene emulsion polymerization method, and examples thereof include benzoyl peroxide, potassium persulfate and ammonium persulfate. Further, a redox type radical initiator may be used for the purpose of controlling the reaction and completely carrying out the polymerization.

Next, an acrylic copolymer which is a copolymer of (a) ethyl acrylate, (b) n-butyl acrylate and (c) an ethylenically unsaturated compound having an epoxy group in the present invention will be described below. To do.

The acrylic copolymer in the present invention is
The main component is (a) ethyl acrylate and (b) n-butyl acrylate, and the use ratio of (a) and (b) is 0 to 80% by weight of (a) ethyl acrylate,
100 to 20% by weight of (b) n-butyl acrylate
(However, the ratio between (a) and (b) is 0/10.
Unless it is 0) . By setting the composition in this range, excellent ozone resistance is exhibited. When more excellent ozone resistance is required, the ethyl acrylate of (a) is 0
˜60% by weight, 10% of (b) n-butyl acrylate
It is more preferably in the range of 0 to 40% by weight. In consideration of injection moldability, the use ratio of (a) and (b) is 40 to 60% by weight of ethyl acrylate of (a),
Most preferably, the n-butyl acrylate of (b) is in the range of 60-40% by weight.

Further, the acrylic copolymer in the present invention has an ethylenically unsaturated compound (c) having an epoxy group as an essential component, and it is important that it has a structure in which an epoxy group is introduced into the copolymer. it is conceivable that. Examples of the ethylenically unsaturated compound having an epoxy group (c) include, but are not limited to, glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ester. The amount of these used is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the total amount of ethyl acrylate (a) and n-butyl acrylate (b), but 0.5 to 2 parts by weight. The range of parts is more preferable.
By using the ethylenically unsaturated compound having an epoxy group of (c), the injection moldability can be improved and the ozone resistance, especially the cutting life in the ozone test is improved.

As a method for polymerizing the acrylic copolymer of the present invention, any known method can be used, but a method by emulsion radical polymerization is generally used.

As the emulsifier for emulsion polymerization of the acrylic copolymer, various emulsifiers similar to those used for chloroprene polymerization can be used.

In the emulsion polymerization of the acrylic copolymer, a chain transfer agent may be used. For example, alkyl mercaptan such as dodecyl mercaptan, xanthogen disulfide such as diethyl xanthogen disulfide,
A halogenated hydrocarbon such as iodoform can be used.

The emulsion polymerization temperature of the acrylic copolymer is preferably selected from 0 to 90 ° C. At 0 ° C. or lower, water coagulation becomes a problem, and at 90 ° C. or higher, water evaporation becomes a problem.

The chloroprene polymer composition of the present invention comprises
Chloroprene-based polymer, (a) ethyl acrylate,
It is essential to contain an acrylic copolymer characterized by being a copolymer of (b) n-butyl acrylate and (c) an ethylenically unsaturated compound having an epoxy group. The content ratio is not particularly limited, in order to obtain a composition excellent in ozone resistance and injection moldability without impairing various physical properties originally possessed by chloroprene rubber, the content of the acrylic copolymer is The range of 3 to 60% by weight is preferable, the range of 10 to 40% by weight is more preferable, and the range of 20 to 30% by weight is further preferable.

The method for producing the chloroprene-based polymer composition of the present invention is not particularly limited, but the acrylic copolymer and the chloroprene-based polymer may be mixed, for example, obtained by emulsion polymerization. A method of mixing latex and emulsion, a method of kneading solid polymers with an open roll, a kneader, a Banbury mixer, a single-screw or twin-screw extruder, a method of blending solutions dissolved in an organic solvent, etc. Is used. Among them, the method of mixing in the form of a latex obtained by emulsion polymerization and an emulsion is preferable because a uniform mixture can be easily obtained.

The chloroprene polymer of the present invention is excellent in ozone resistance and injection moldability, and also retains the excellent mechanical properties originally possessed by the chloroprene polymer. It is suitable for applications that require high ozone resistance, and is suitable as a material for rubber boots, specifically constant velocity joint boots, rack and pinion boots, ball joint boots, etc. in the automobile industry. is there. It can also be used as other rubber products, such as rubber hoses, specifically brake hoses, power steering hoses, fuel hoses, radiator hoses, automotive air hoses such as car air conditioner hoses, and exterior rubber materials such as various high pressure hoses. Is also suitable. Furthermore, the chloroprene polymer composition of the present invention is also suitable as a material for building gaskets, specifically, airtight, spacers, glazing gaskets, joint gaskets, zipper gaskets, setting blocks, expansions, etc. It is also suitable for anti-vibration rubber and belts.

[0025]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples. In the following description, parts and% are based on weight.

Chloroprene polymer latex (A1)
Production: in 3 liters of glass Kolben under a nitrogen stream, 100 parts of water, 5 parts of disproportionated rosin acid as emulsifier, 1.0 part of potassium hydroxide, sodium salt of formaldehyde naphthalene sulfonic acid condensate as dispersant 0 8 parts were charged, and after dissolution, a mixture of 100 parts of chloroprene and 0.1 part of n-dodecyl mercaptan was added with stirring, and polymerization was performed at a polymerization temperature of 40 ° C. using potassium persulfate as a radical polymerization initiator, When the monomer conversion rate reached 65%, tert-butylcatechol and thiodiphenylamine were added to terminate the polymerization, and unreacted monomers were removed under reduced pressure to remove the chloroprene polymer latex (A1). Got

Chloroprene polymer latex (A2)
Production of chloroprene polymer latex (A) except that 95 parts of chloroprene and 5 parts of 2,3-dichloro-1,3-butadiene were used instead of 100 parts of chloroprene.
A chloroprene polymer latex (A2) was obtained in the same manner as in 1).

Acrylic copolymer emulsion (B1 to B
Preparation of 11) In a 3 liter glass Kolben under a nitrogen stream, water 15
0 parts and 7.5 parts of sodium dodecylbenzenesulfonate as an emulsifier were charged and dissolved, and then the monomers shown in Table 1 and 0.01 parts of n-dodecyl mercaptan were added with stirring. Acrylic copolymer emulsions (B1 to B11) were obtained by performing polymerization at a polymerization temperature of 70 ° C. using potassium persulfate as a radical initiator until the monomer conversion rate (98%) was reached.

Examples 1 to 10 and Reference Example 1 Chloroprene polymer latex (A1, A2) and acrylic copolymer emulsion (B1 to B5, B9 to B1)
1) in the combination and blend ratio shown in Table 2,
After sufficiently stirring and mixing, a chloroprene polymer composition was obtained by a freeze-coagulation drying method.

Comparative Examples 1 to 4 The chloroprene polymer latex (A1) and the acrylic copolymer emulsion (B6 to B8) were sufficiently stirred and mixed in the combinations and blending ratios shown in Table 3,
A chloroprene polymer composition was obtained by the freeze-drying method.

The chloroprene polymer compositions (crude rubber) of the above Examples and Comparative Examples were made into rubber blends according to the formulations shown in Table 4. The unvulcanized rubber composition was subjected to an injection molding test to determine the surface skin condition. 2 at a temperature of 160 ° C
After press vulcanization for 0 minutes, the physical properties of the vulcanized sheet (thickness 2 mm) were tested. JIS- for hardness, tensile strength and elongation
Compliant with K6301, ozone resistance is JIS-K62
A dynamic ozone test (tensile method) was carried out in accordance with No. 59, and crack generation time and cutting time were measured. The test results are shown in Table 5 and Table 6.
Shown in.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

[Table 5]

[0037]

[Table 6]

[0038]

As described above, the chloroprene polymer composition of the present invention is excellent in ozone resistance and injection moldability, and also retains the excellent mechanical properties originally possessed by the chloroprene polymer. ing. Therefore, it is particularly suitable for applications molded by injection molding and requires excellent ozone resistance. In the automobile industry, rubber boots, specifically, constant velocity joint boots, rack and pinion boots, ball joint boots, etc. It is suitable for use as a material.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-311248 (JP, A) JP-A-62-116651 (JP, A) JP-A-62-30155 (JP, A) JP-A-62- 236841 (JP, A) JP 62-78273 (JP, A) JP 4-202207 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 11/00 C08L 33 / 04 C08L 63/00

Claims (3)

(57) [Claims] 1. A chloroprene-based polymer comprising (a) ethyl acrylate, (b) n-butyl acrylate and (c).
It contains a copolymer with an ethylenically unsaturated compound having an epoxy group, and the ratio of (a) and (b) is 8 by weight.
0/20 to 0/100 (However, if 0/100
The chloroprene polymer composition characterized in that it is excluded). 2. A chloroprene-based polymer containing (a) ethyl
Acrylate, (b) n-butyl acrylate and (c)
Copolymerization with ethylenically unsaturated compounds containing epoxy groups
It contains a body, and the ratio of (a) and (b) is 8 by weight.
Chlorophyte characterized by 0/20 to 10/90
Len-based polymer composition. 3. A chloroprene polymer latex,
(A) Ethyl acrylate, (b) n-Butyl acrylate, and (c) Epoxy group-containing ethylenically unsaturated compound are mixed to obtain a copolymer emulsion, and a chloroprene polymer composition is produced. Method.