JPS5952884B2 - Production method of chloroprene polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a process for making chloroprene polymers useful in resin-modified roloprene adhesives that do not undergo phase separation during storage or use.

Solvent adhesives containing chloroprene polymers typically include reaction products of certain basic metal oxides and heat-reactive phenol formaldehyde resins. Immediately after production, this type of adhesive has a uniform opaque dispersed phase, but if it is left to stand for a long time, a transparent or opaque upper layer forms, and the lower layer is filled with metal oxides and inorganic fillers. There is a tendency for the agent to sediment and become unevenly distributed, separating into two layers called layer separation. This layer-separated adhesive is inconvenient because it must be redispersed before use. Many methods have been proposed to overcome this layer separation problem. For example, Japanese Patent Publication No. 49-32783 describes the use of limited unsaturated fatty acids in the emulsion polymerization of chloroprene in order to reduce the amount of rosin acid as an emulsifier and increase the colloidal stability of the latex. A method is disclosed in which limited amounts of each of a condensate of formaldehyde and naphthalene sulfonic acid are used to prevent the formation of coagulum.

However, the layer separation properties of the polymers produced by this method have not yet been sufficiently improved, and further improvements in storage stability and roll processability are desired. Furthermore, Japanese Patent Publication No. 51-24385 discloses a method using limited amounts of saturated or unsaturated fatty acids or alkali metal salts thereof and modified rosin acid derivatives as emulsifiers.

However, according to this method, the colloidal stability of the latex during or after the polymerization process is insufficient, coagulation tends to occur, and the layer separation property of the obtained polymer is not sufficiently improved. According to the present invention, a method for producing a chloroprene polymer in which latex has sufficient colloidal stability and polymer layer separation resistance is provided.

That is, in the present invention, per 100 parts by weight of total monomers, (a
) 1.5 to 3 parts by weight of rosin acid, (b) 0.5 to 1.5 parts by weight
parts by weight of sulfated or sulfonated aliphatic carboxylic acids having 12 to 18 carbon atoms, and (00.5 to 1.5 parts by weight of each of 7 aliphatic monocarboxylic acids having 12 to 18 carbon atoms) a water-soluble salt is present, and (a)
, (b) and (c) indicate the proportion as an acid, and the chloroprene polymer or copolymer is characterized by emulsion polymerization of chloroprene or a monomer copolymerizable with it in an amount of up to 50% by weight. The gist is the manufacturing method.

According to the present invention, monomers mainly containing chlorobrene are emulsion polymerized using water-soluble salts of the above (a), (b), and (c) as emulsifiers.

In the above-mentioned Japanese Patent Publication No. 4}-32783, a condensation product of formaldehyde and naphthalene sulfonic acid, which is an emulsified polymer, is used.

However, although this condensation product improves the colloidal stability of the latex, it does not contribute to improving the phase separation properties of the polymer. In the present invention, it is not essential to use a condensation product of formaldehyde and naphthalene sulfonic acid, but rather a water-soluble salt of a sulfated aliphatic carboxylic acid or a sulfonated carboxylic acid having 12 to 18 carbon atoms. One of the characteristics is that it uses .

An example of using a salt of rosin acid and sulfated oleic acid as an emulsifier for emulsion polymerization of chlorobrene is disclosed in U.S. Pat. No. 3,838,141.
However, there is no suggestion at all about the combined use of aliphatic salts and carboxylic acid salts, or about improving the layer separation properties of the resulting polymer. Sulfated or sulfonated carboxylic acids not only contribute to the colloidal stability of the latex, but also have a significant effect on the phase separation stability of the resulting polymer. The sulfated or sulfonated fatty cocarboxylic acids used in the present invention may be saturated or unsaturated, such as sulfated oleic acid, sulfated stearic acid, sulfonated lauric acid, and sulfonated palmitic acid. The sulfated or sulfonated aliphatic carboxylic acid is used in an amount of 0.5 to 1.5 parts by weight, preferably 0.6 to 1.2 parts by weight, per 100 parts by weight of total monomers. If the amount is less than 0.5 parts by weight, there is a high risk that undesirable coagulates will precipitate during the neutralization step prior to separating the polymer from the latex.

The effect is sufficient when the amount is up to 1.5 parts by weight, and if the amount is more than 1.5 parts, it is not only uneconomical, but also there is a risk that the latex may flow out during the polymer washing process. In order for the latex to have sufficient colloidal stability to be processed in conventional manner, 1.5
At least parts by weight of rosin acid must be used.

However, if the amount exceeds 3 parts by weight, the layer separation stability of the resulting polymer will not be satisfactory. The preferred amount of rosin acid used is 1.5 to 2.5 parts by weight per 100 parts by weight of total monomers. Furthermore, in the present invention, an aliphatic monocarboxylic acid having 12 to 18 carbon atoms is used as one of the emulsifiers.

This carboxylic acid may be saturated or unsaturated, and examples include lauric acid, palmitic acid, stearic acid, and oleic acid. The monocarboxylic acid is used in an amount of 0.5 to 1.5 parts by weight per 100 parts by weight of the total monomers. 0
．． If the amount is less than 5 parts by weight, the layer separation property of the resulting polymer will be insufficient, and if it exceeds 1.5 parts by weight, the layer separation property will deteriorate again and the adhesiveness of the polymer will also decrease.

The preferred amount used is 0.5 to 1.0 parts by weight. Said (
The acids a), (b) and c) act as water-soluble salts, such as sodium, potassium or ammonium salts.

In implementing the method of the present invention, the above (a), (
In addition to the water-soluble salts b) and (c), it is also possible to use other emulsifiers or dispersants, for example water-soluble salts of condensates of naphthalenesulfonic acid and formaldehyde.

The method of the present invention is carried out by a conventional method for chloroprene polymerization, except for using the above-mentioned emulsifier.

In the present invention, chloroprene alone can be polymerized as a monomer, or other copolymerizable monomers can also be used in place of chloroprene up to 50%.

Polymerization is carried out in the usual manner.

For example, a conventional chain transfer agent may be used in the amount necessary to obtain a polymer of a desired viscosity, and the resulting polymer may be a sol. Examples of common chain transfer agents are alkyl mercaptans, dialkyl zandogen disulfides and iodoform. The polymerization temperature is 0 to 50°C, with a preferred range of 5 to 15°C. Polymerization is initiated and maintained by adding a suitable catalyst that generates free radicals. Examples of suitable catalysts are organic or inorganic peroxides such as potassium persulfate, dibenzoyl peroxide, hydrogen peroxide and cumene hydroperoxide or azobisisobutyronitrile. The conversion rate of all monomers into polymer is 55% or more, preferably 60% or more. A common polymerization inhibitor such as t-butylcatechol or thiodiphenylamine is used to terminate the polymerization.

A known method can be used to isolate the polymer from the latex.

The polymer obtained in the present invention can be used as a base for ordinary chloroprene adhesives.

5 By using the chloroprene polymer obtained by the production method of the present invention as a base and adding metal oxides such as zinc white and magnesia, a modified phenolic resin, an organic solvent, and ordinary additives to this in a conventional manner. It is possible to obtain an adhesive with the same tackiness and adhesion as before, but with significantly improved layer separation stability.The modified phenolic resin added to the polymer obtained in the present invention is The amount of inorganic fillers such as codium chloride, zinc white, and other inorganic fillers can be varied from 1 to 50 parts by weight, respectively.

The metal oxide may be added to the rubber on a roll or added to the rubber solvent. Pre-reaction is not necessarily required for the resin and metal oxide, and the effect on two-layer separation is not affected even if added directly to the rubber solution. As the organic solvent, various solvents and mixed solvents that can dissolve polychloroprene can be used. Next, the present invention will be explained by examples.

Parts or percentages are expressed by weight. Examples 1 to 4 Chlorobrene monomer was charged into a 31 flask equipped with a stirrer and a cooling coil according to the recipe shown in Table 1, and as a polymerization catalyst, potassium persulfate 0.5% and anthraquinone-β-sulfone were added. A mixed aqueous solution containing 0.05% sodium acid was added, and polymerization was carried out at 10° C. in a nitrogen stream.

0.01 part of phenothiazine, 0.05 part of diethylhydroxylamine, and 2 parts of tetraethylthiuram disulfide
Polymerization was stopped at a conversion rate of 85% by adding an emulsion containing 100% of the monomer, and unreacted monomers were removed under reduced pressure.

Add 10% acetic acid aqueous solution to the alkaline emulsion and mix.
The polymer was separated and dried on a freezing roll.

Mooney viscosity MS2+2.5 (hereinafter abbreviated as MS2+2.5) at 100℃ using a small sample rotor
ranged from 43 to 46.

Example 5 The same conditions as in Example 4 were carried out except that the polymerization rate was 70% and tetraethylthiuram disulfide was removed from the polymerization terminator.

The MS2+2.5 of the sample was 48.

Example 6 The same conditions as in Example 1 were carried out except that 0.8 part of sulfonated lauric acid was used instead of 0.8 part of sulfated oleic acid.

Comparative Example 1 The same conditions as in Example 1 were carried out except that the amount of rosin acid and oleic acid as emulsifiers were changed to 3.5 parts and 0.5 parts, respectively.

Comparative Example 2 The same conditions as in Example 1 were carried out except that the amount of rosin acid and oleic acid as emulsifiers were changed to 2.5 parts and 1.75 parts, respectively.

A chloroprene-modified resin-based one-solvent adhesive was prepared from the obtained sample according to the following procedure.

Chloroprene? A blend is obtained by kneading 100 parts of Lima, 4 parts of magnesia, and 5 parts of zinc white using a conventional open roll.

109 parts of this blend and 686 parts of a resin solution (80 parts of resin/606 parts of solvent) prepared by dissolving heat-reactive phenol formaldehyde resin A, B, or C in a solvent are stirred and dissolved for 12 hours. This adhesive has an inner diameter of 20 m.
The mixture was weighed into a glass sample tube with a height of 200 mm and stored in a room at a temperature of 21° C. to 24° C., and the state of layer separation was observed, and the degree of separation was expressed by the following formula.

Thirdly, the test results of layer separation due to adhesive storage are shown.

Claims (1)

[Claims] 1. (a) 1.5 to 3 parts by weight of rosin acid, (b) 0.5 to 1.5 parts by weight of 12 to 18 carbon atoms per 100 parts by weight of total monomers. a oxidized or sulfonated aliphatic carboxylic acid having
c) 0.5 to 1.5 parts by weight of the respective water-soluble salts of aliphatic monocarboxylic acids having 12 to 18 carbon atoms are present, and amounts of (a), (b) and (c) A method for producing a chloroprene polymer or copolymer, characterized in that chloroprene or a monomer copolymerizable with it in an amount of up to 50% by weight is emulsion polymerized.