JPH01185310A - Manufacture of chloroprene copolymer - Google Patents

Abstract

PURPOSE:To produce a chloroprene copolymer modified with sulfur extremely excellent in elongation fatigue resistance, by subjecting chloroprene to suspension polymerization in the presence of prescribed amounts of a specific monomer and sulfur at or above a specific temperature. CONSTITUTION:98-75wt.% 2-chlorobutadiene-1,3 (hereinafter referred to as chloro prene) and 2-25wt.% 2,3-dichlorobutadiene-1,3 monomer are subjected to suspen sion polymerization in the presence of 0.1-1.5pts.wt. sulfur for 100pts.wt. mono mer at a polymerization temperature of 45 deg.C or above to produce a chloroprene copolymer. The resulting polymer has extremely excellent elongation fatigue resistance which is not observed at all in the prior chloroprene polymers modi fied with sulfur.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a 2-chlorobutadiene-1,3 (hereinafter referred to as chloroprene) copolymer.

More specifically, the present invention relates to a method for producing a sulfur-modified chloroprene polymer having extremely excellent stretch fatigue resistance.

(Conventional technology and problems) Sulfur-modified chloroprene polymer is a copolymer of sulfur and chloroprene, and has well-balanced physical properties such as oil resistance, weather resistance, and ozone resistance that chloroprene polymer has. In addition, it has excellent properties such as high elasticity and high tearability, so it is widely used in various industrial products. However, it is still insufficient in terms of elongation fatigue resistance, and it is desired to improve this elongation fatigue resistance. If the tensile fatigue resistance is improved, it will become possible to use the material under harsh conditions where it is subject to severe stretching and bending, such as automobile boots and belts, and the development thereof has been particularly desired in recent years.

There are many known documents regarding the production method of sulfur-modified chloroprene polymers, and recently there is a report (Japanese Patent Application Laid-Open No. 60-31510) aimed at improving wear resistance, but the main focus is on improving stretch fatigue resistance. I couldn't see what I put there.

(Means for Solving the Problems) In order to improve these drawbacks and meet the demands, the present inventor conducted extensive research on a method for improving the tensile fatigue resistance of sulfur-modified chloroprene polymers. The present inventor discovered that a sulfur-modified chloroprene polymer having extremely excellent stretch fatigue resistance can be obtained by carrying out emulsion polymerization at 45°C or higher in the presence of 2,3-dichlorobutadiene-1,3 monomer. invention has been achieved.

That is, the present invention uses 98 to 75% by weight of chloroprene and 2 to 75% by weight of chloroprene.
25% by weight of 2,3-dichlorobutadiene-1,3 monomer and 100 parts by weight of the monomer, 0.1 to 1.5
The present invention provides a method for producing a sulfur-modified chloroprene polymer, which is characterized by carrying out emulsion polymerization at a polymerization temperature of 45°C or higher in the presence of parts by weight of sulfur.

The chloroprene polymer obtained under the conditions specified in the present invention is a chloroprene polymer that has extremely excellent stretch fatigue resistance that has not been found in any conventional sulfur-modified chloroprene polymer, and is achieved for the first time by the present invention. It is what was done. What is important in the present invention is that if even one of the conditions specified in the present invention is missing, the desired chloroprene polymer cannot be obtained. The present invention will be explained in detail below.

The amount of 2,3-dichlorobutadiene-1,3 used in the production of the sulfur-modified chloroprene polymer of the present invention is 2 to 25% by weight based on the total monomers of chloroprene and 2,3-dichlorobutadiene-1,3. It is important to use within the range. 2% by weight of 2,3-dichlorobutadiene-1,3
If it is less than 25% by weight, the tensile fatigue resistance is poor, and if it exceeds 25% by weight, processing is possible, but pebutization becomes impossible until the viscosity is reached.

In the present invention, a more important point is the amount of sulfur added. The amount of sulfur is 0.1 to 1 per 100 parts by weight of total monomers.
．． 5 parts by weight, preferably 0.3 to 1.5 parts by weight, 0.1
If it is less than 1.5 parts by weight, it will not have the characteristics of a sulfur-modified chloroprene polymer, and if it exceeds 1.5 parts by weight, the Mooney viscosity of the compound will decrease too much during processing, resulting in a decrease in workability.
This is because the tensile fatigue resistance, which is the objective of the present application, decreases.

Also, when a sulfur-modified chloroprene heavy body having a low Mooney viscosity is required, other modifiers such as dialkylxanthogen disulfide, n-dodecyl mercaptan, t
-Dodecylmercaptan, iodoform, etc. may be used in combination. The dialkyl xanthogen disulfide has alkyl groups each having 1 to 8 carbon atoms in length, and examples of suitable alkyl groups include ethyl and isopropyl groups.

The monomer in which a predetermined amount of sulfur has been dissolved is mixed and stirred with an aqueous emulsion containing an emulsifier and subjected to polymerization.

Emulsion polymerization in this case can be carried out by conventionally known methods. As an emulsifier, for example, a carbon number of 6 to 22 is used.
An alkali metal salt of a saturated or unsaturated fatty acid, an alkali metal salt of rosin acid or a disproportionated rosin acid, an alkali metal salt of a formalin condensate of β-naphthalenesulfonic acid, etc. are used.

The polymerization temperature is another essential condition of the present invention, and the appropriate temperature is 45°C or higher, preferably in the range of 50 to 55°C. If the polymerization temperature is too high, equipment problems will occur, so 60°C is the practical limit.

As the catalyst, those normally used for polymerization of chloroprene may be used, such as potassium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and the like.

Polymerization is carried out to a conversion rate of 50 to 95%, preferably about 70 to 90%, and is then stopped by adding a small amount of a polymerization inhibitor. Examples of polymerization inhibitors include water-soluble groups such as thiodiphenylamine, 4-tert-butylcatechol, 2,2'-methylenebis-4-methyl-6-tert-butylphenol, and dialkylthiocarbamic acid. It is added in a range of 0.01 to 20% by weight.

The polymer thus obtained may be used as it is, or the Mooney viscosity may be adjusted by peptization.

Veptization is carried out in the range of 1.5 to 3.0% by weight of tetraalkylthiuram disulfide or in general R-
``thiol of S H or its ionizable sulfenyl form R3-Me'' (Me is an alkali cation or ammonium, R is a chain or branched alkyl group having 2 to 6 carbon atoms, or alkyl An aryl group, an arylcarbonyl group, an alkylcarboxyl group, an alkylnaphthyl or naphthyl group, an arylthiazole or thiadur group or its sodium group, an arylimidazole or imidazole group, an alkylxanthate group or a dialkylthiocarbamoyl group, and for the polymer, 0.1-3.0% by weight
It is carried out at a temperature of 20 to 60° C. until a predetermined viscosity is reached. Examples of the tetraalkylthiuram disulfide used for peptization include tetraethylthiuram disulfide and tetrabutylthiuram disulfide. Small amounts of stabilizers can also be included in the polymer to prevent Mooney viscosity changes during storage. Examples of such stabilizers include phenyl-alpha-naphthylamine, octylated diphenylamine, 2,6-di-t-butyl-4-phenylphenol,
Examples include 2.2'-methylenebis(4-methyl-6-t-butylphenol) and 4.4'-thiobis-(6-t-butyl-3-methylphenol).

The polymer can be isolated by adjusting the pH of the latex to 5.5 to 7.5, and using conventional methods such as freeze-coagulation, washing with water, and drying with hot air.

(Examples) The present invention will be further explained below with reference to Examples, but it is not limited to these Examples.

Examples 1 to 5 and Comparative Examples 1 to 4 Chloroprene and other chemicals were charged in a 4-sol flask with an internal volume of 51 according to the polymerization recipe shown in Tables 1 and 3, and polymerized in a nitrogen stream using potassium persulfate as a catalyst. I did it. When the conversion rate reached 80%, dimethylammonium dimethyldithiocarbamate was dissolved in water to stop the reaction, and then an emulsion of 2.0 parts of tetraethylthiuram disulfide was added, the temperature was raised to 40°C, and the mixture was peptized for 5 hours. The peptized latex was steam-distilled to remove unreacted additives, and the dried polymer was isolated by a conventional freeze-coagulation method.

The obtained polymer was blended according to the formulation shown in Table 2, and 1
Press vulcanization was performed at 60° C. for 20 minutes to obtain a vulcanized product.

-1 layer of water (.) water
130 Potassium rosinate 4.5
β-naphthalenesulfonic acid formalin 0.6 Condensate sodium salt Sodium hydroxide 0.4-12
Polymer 100 Stearic acid 1) I MgO2) 4 FEF carbon blank 3) 5゜Rapese oil 4'1゜Dioctyl sebaque) S) 1゜Zn
O” 5 Ethylenethiourea 7ゝ 1 Tetramethylthiuram disulfide II) o, s〈Note〉 1)
Product Name: Nirnak S-302) Product Name: Kyowa Mug #
15゜3) Product name: Asahi #60 4) Manufactured by Ajinomoto Co., Inc. 5) Product name: Sancera-Dos 6) Product name: Zinchua No. 1 7) Product name: Suncera-223 8) Product name Nick Cellar TT Table Examples 1 to 5 of -3 are chloroprene copolymers prepared under the conditions that the amounts of chloroprene, 2,3-dichlorobutadiene-L3, and sulfur were set within the claimed range, and the polymerization temperature was 45°C or higher. These are the results of measuring elongation fatigue properties and normal physical properties using Note that the normal state physical properties were measured in accordance with JIS-K6301. The elongation fatigue property was evaluated as follows. Using a Demarcher type bending tester, the stretching ratio of the No. 3 dumbbell piece was 10 with respect to the scale line spacing.
A No. 3 dumbbell piece sample was repeatedly stretched at 300 cpm at room temperature, and the number of times the sample broke was measured. Measurements were carried out using n-50 samples each.
Assuming that the results follow the Weibull distribution, the average life μ and the slope m of the straight line were determined. Here, μ is the average number of breaks,
m is a parameter expressing the degree of variation in the number of breaks, and the details are described in, for example, "How to Use Weibull Probability Paper" edited by the Japanese Standards Association.

Comparative example 1 is when sulfur is not added, comparative example 2 is 2.3
-Dichlorobutadiene-1,3 was added in excess.

It is clear that the examples determined are significantly superior in terms of elongation fatigue resistance.

1. Patent Applicant Denki Kagaku Kogyo Co., Ltd. Procedural Amendment February 17, 1988 Director General of the Patent Office Mr. Kunio Ogawa ■, Indication of the Case Patent Application No. 7824 No. 7824 of 1988 2, Name of Invention Chlorobrene Copolymer Manufacturing process 3, relationship with the case of the person making the amendment Address of the patent applicant ■100 Detailed explanation of the invention in the specification 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Column 5, Contents of the amendment (1) Specification No. On page 4, lines 5 and 6, "viscosity that can be processed" is corrected to "viscosity that can be processed."

(2) "Water-soluble group" on page 6, line 7 of the specification is corrected to "water-soluble salt."

Ko version

Claims (1)

[Claims] 98-75% by weight of 2-chlorobutadiene-1,3 and 2
-25% by weight of 2,3-dichlorobutadiene-1,3 monomer and 0.1-1.
A method for producing a chloroprene copolymer, comprising carrying out emulsion polymerization at a polymerization temperature of 45° C. or higher in the presence of 5 parts by weight of sulfur.