JPH1135604A - Production of chloroprene-based rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved method for producing a chloroprene-based polymer, capable of preventing adhesion of scale on the surface of a polymerizer or on the surface of auxiliary facilities in the polymerizer during polymerization while maintaining stability of a latex which a chloroprene-based latex essentially has or basic characteristics such as physical properties which the chloroprene- based latex essentially has. SOLUTION: In polymerizing a 2-chloro-1,3-butadiene monomer alone or a monomer mixture containing the 2-chloro-1,3-butadiene monomer and another monomer copolymerizable with the monomer, the polymerization is carried out by using a polymerizer obtained by forming a coated film composed of a compound of the formula ((n) is an integer of 2-300) on the surface of the polymerizer or on parts, with which the monomer is brought into contact, of the surface of auxiliary facilities in the polymerizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to 2-chloro-1,2-chloro-1,
3-butadiene monomer (hereinafter often abbreviated as chloroprene) alone or a monomer mixture containing a 2-chloro-1,3-butadiene monomer and another monomer copolymerizable therewith (hereinafter often referred to as chloroprene) Abbreviated as chloroprene-based monomer, and the polymer is referred to as a chloroprene-based polymer). The present invention relates to an improved method for producing a polymer, which prevents the polymer scale from adhering to a portion where the polymer contacts.

[0002]

2. Description of the Related Art Emulsion polymerization is generally used as a method for polymerizing a chloroprene-based monomer. In the polymerization, a portion of the inner surface of the polymerization vessel and a surface of ancillary equipment inside the polymerization vessel where the monomer comes into contact is used. Not a little polymer scale was sometimes attached. Such adhesion of scale causes disadvantages such as a decrease in the polymer yield and a decrease in the cooling capacity of the polymerization reactor. Further, in the case of a chloroprene latex product, there is a problem that the scale is peeled off and mixed into the product, thereby deteriorating the quality of the product. Furthermore, it takes time and effort to remove the adhered scale, which further reduces productivity.

[0003] As a measure for preventing such scale adhesion, for example, in the polymerization of vinyl chloride, various adhesion inhibitors or dispersion stabilizers have been proposed (Japanese Patent Laid-Open No. Hei 4 (1994)).
JP-A-81404, JP-A-58-180510, JP-A-58-11504, JP-A-61-78
811, JP-A-62-91505, JP-A-61-115906, etc.). However, with regard to emulsion polymerization of chloroprene, no effective measures have been known to avoid adhesion of scale.

[0004]

In emulsion polymerization of chloroprene-based monomers, the polymerization of chloroprene-based latex can be carried out without impairing the stability of the chloroprene-based latex during the polymerization, the properties of the obtained polychloroprene-based latex or the properties of chloroprene rubber. It has been desired to develop a means for preventing the adhesion scale generated therein.

[0005] The present invention is intended to improve the stability of the latex inherent in the chloroprene-based latex or the basic properties such as the physical properties inherent in the polymer while maintaining the inner surface of the polymerization vessel and the surface of the equipment inside the polymerization vessel during the polymerization. It is an object of the present invention to provide an improved method for producing a chloroprene-based polymer by preventing the generated scale from adhering.

[0006]

That is, the present invention provides 2-
A polymerization vessel used for polymerizing a chloro-1,3-butadiene monomer alone or a monomer mixture containing a 2-chloro-1,3-butadiene monomer and another monomer copolymerizable therewith. Using a polymerization can in which a coating containing the compound (A) represented by the following general formula (1) is formed on the inner surface and the portion of the auxiliary equipment inside the polymerization can that comes into contact with the monomer, The present invention relates to a method for producing a 2-chloro-1,3-butadiene polymer, which is characterized by performing polymerization.

[0007]

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(Where n is an integer of 2 to 3000)

Hereinafter, the present invention will be described in detail. In the present invention, first, a compound represented by the following general formula (1) is formed on the inner surface of a polymerization vessel to be used and the surface of ancillary equipment inside the polymerization vessel such as a stirring blade (hereinafter, often abbreviated as the inner surface of the polymerization vessel) ( A coating containing A) is formed.

[0010]

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(Where n is an integer of 2 to 3000)

The compound (A) represented by the above-mentioned general formula (1) is composed of at least one kind of a repeating unit represented by the following chemical formulas (4) to (10), if its chemical structure is specifically shown. . In the following Chemical Formulas 4 to 10, R1 of each formula
One of R3 to R3 is an OH group, and the other is hydrogen. The position of the OH group may be the same or different for each repeating unit.

[0013]

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[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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[0019]

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For the purpose of uniform coating film formation and efficient spraying, a diluting solvent, a pressure-sensitive adhesive, a dispersing aid and the like are preferably used in combination as long as the effects of the present invention are not impaired. A typical solvent is water.

When the compound (A) of the present invention is applied, if the presence of any contaminant which hinders the formation of the above-mentioned coating film on the inner surface of the polymerization vessel and the surface of the equipment inside the polymerization vessel is expected, Surface cleaning using organic solvents and detergents,
It is preferable to perform a rinsing operation or the like with pure water to expose a clear metal surface or the like. Examples of commercially available aqueous solutions containing the compound (A) of the present invention include NOXOL WSW, NOXOL ETH, and NOXO manufactured by CIRS.
LETH / S.

When the compound (A) of the present invention is applied to the inner surface of the polymerization vessel, the coating amount is as follows:
0.001 to 0.5 g / m ² , preferably 0.003 to
It is in the range of 0.1 g / m ² . If it is less than 0.001 g / m ² , the effect of suppressing scale adhesion is small. 0.5g /
no remarkable effect by applying an amount of more than m ^2, also,
Not economic. Examples of the method of application include application using a roller, a brush, or the like, spraying, and spraying using a known atomizing device such as a steam ejector. After application, it is desirable to heat at a temperature of 50C to 150C in order to form a strong coating film or to volatilize volatile components.

After such a coating film is formed, a rinsing operation of washing away the excess compound (A) remaining on the inner surface of the polymerization can with pure water is a very desirable operation from the viewpoint of effectively exhibiting the effects of the present invention. With one application, one or more polymerizations can be performed until the effect is attenuated. The frequency of application depends on the conditions of use, and reapplication is performed before the effect is attenuated. Further, the formation of the coating film of the compound (A) described above is preferably performed in an atmosphere of an inert gas such as a nitrogen gas or an argon gas. If it comes into contact with oxygen in the air for a long time, a sufficient effect may not be exhibited. The material of the polymerization can or the like in which the present invention is suitably implemented is stainless steel or the like, and may be coated with glass lining or rubber lining.

Next, the polymerization of a chloroprene monomer alone or a mixture of a chloroprene monomer and a copolymerizable monomer with the chloroprene monomer is carried out using a polymerization vessel in which a coating film of the compound (A) is formed. It is carried out in an aqueous emulsion in the presence of a suitable radical initiator. Examples of the emulsifier include alkali metal salts of saturated or unsaturated fatty acids having 6 to 22 carbon atoms, alkali metal salts of rosin acid or disproportionated rosin acid, alkali metal salts of formalin condensate of β-naphthalenesulfonic acid, For example, polyvinyl alcohol having an average degree of polymerization of 200 to 3000 is used.

Examples of monomers copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene and
1-chloro-1,3-butadiene, sulfur, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, methacrylic acid and esters thereof, and the like, as long as the properties inherent in the chloroprene polymer are not impaired. Can be.

As the chain transfer agent, alkyl mercaptan, dialkyl xanthogen sulfide and the like are used. As the polymerization initiator, organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide and t-butyl hydroperoxide are used.
Polymerization temperature is 0 to 55 ° C, monomer conversion is 50 to 100%
It is performed in the range. Examples of the polymerization inhibitor for stopping the polymerization before the monomer conversion reaches 100% include thiodiphenylamine, 4-tert-butylcatechol, and 2,2-methylenebis-4-methyl-6-tert-butyl. Libutylphenol and the like are used.

Unreacted monomers are removed by, for example, a steam stripping method. The polychloroprene latex thus obtained can be used as a raw material for a latex adhesive. Alternatively, the pH of the polychloroprene latex is adjusted to 5.5 to 7.5, and the polymer can be isolated and used by a conventional method such as freeze coagulation, washing with water, or hot air drying.

[0028]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited by these examples.

Example 1 A nitrogen gas was introduced into a stainless steel polymerization vessel having an internal volume of 250 liters at a flow rate of 1 L / min for 15 minutes to replace with nitrogen. Thereafter, an aqueous solution containing compound (A) (NOXOL WSW manufactured by CIRS) was adjusted using a steam ejector (steam pressure: 4 kg / cm ² ) so that the temperature at the tip of the nozzle was 80 ° C. It was sprayed onto the inner surface of the polymerization vessel, the stirring shaft, and the surface of the stirring blade so that the solid content of A) was 0.03 g / m ² . Thereafter, the inside of the polymerization can was kept at 80 ° C. for 15 minutes. During this spraying operation, a nitrogen atmosphere was maintained. Next, pure water was flowed into the polymerization vessel to rinse the same. The water after rinsing was discharged from a valve at the bottom of the can. The polymerization can jacket was cooled with water and allowed to stand for 30 minutes.

According to the polymerization recipe shown in Table 1, a predetermined amount of pure water and polyvinyl alcohol were charged into the polymerization can having the coating film formed thereon, and the mixture was stirred and dissolved at 60 ° C. afterwards,
After cooling and stirring, the monomer and the chain transfer agent were charged and emulsified, an aqueous solution of potassium persulfate was added, and polymerization was carried out at an internal temperature of 40 ° C. for 10 hours. After completion of the polymerization, the obtained latex was extracted and the amount of scale attached on the inner surface of the can was measured. Table 2 also shows the results when polymerization was performed without forming a coating film.

[0031]

[Table 1]

[0032]

[Table 2]

Example 2 In the same manner as in Example 1, an aqueous solution (NOXOL ETH / S manufactured by CIRS) containing the compound (A) was placed on the inner surface of a polymerization vessel having an internal volume of 250 liters. Was applied such that the application amount was 0.03 g / m ² . The chemicals shown in Table 3 excluding the monomer and the chain transfer agent were charged into the polymerization can, and stirred and dissolved at 30 ° C. to prepare a soap solution. Thereafter, the mixture was cooled, the monomer and the chain transfer agent were charged and emulsified, an aqueous solution of potassium persulfate was added, and polymerization was carried out at an internal temperature of 10 ° C. for 5 hours. After the addition of an emulsion of thiodiphenylamine to terminate the polymerization, the obtained latex was extracted and the amount of scale attached to the inner surface of the polymerization was measured. Table 4 also shows the results when polymerization was performed without forming a coating film.

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

As described above, according to the method for producing a chloroprene polymer according to the present invention, it is possible to suppress the adhesion of scale generated on the inner surface of the polymerization vessel during the polymerization, which is extremely useful industrially. .

Claims (1)

[Claims] 1. A 2-chloro-1,3-butadiene monomer alone or a monomer mixture containing a 2-chloro-1,3-butadiene monomer and another monomer copolymerizable therewith. At the time of polymerization, the following general formula (1) is applied to the portion of the inner surface of the polymerization vessel used and the surface of the equipment inside the polymerization vessel that comes into contact with the monomer.
A method for producing a 2-chloro-1,3-butadiene-based polymer, wherein polymerization is performed using a polymerization canister on which a coating film containing the compound (A) represented by the formula (1) is formed. Embedded image (Where n is an integer from 2 to 3000)