JPH0356563B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a fine, uniform, and stable organic solvent dispersion of an AN polymer. In recent years, there has been a demand for fine particulate synthetic polymers as modifiers for plastics, fibers, films, etc., and as surface finishing agents for paper, films, leather, etc. Among them, AN-based polymers have a high light resistance. Because of their excellent weather resistance and solvent resistance, there is a strong desire for the application of particulate AN-based polymers to the above-mentioned fields. As a method for producing such a particulate AN-based polymer,
For example, in Japanese Patent Publication No. 55-2207, an aqueous emulsion of AN polymer was proposed. The emulsion is useful in applications where it is used in an aqueous dispersion state, but in order to obtain a dispersion in an organic solvent, the polymer must be separated from the aqueous emulsion and then redispersed in an organic solvent. Not only is this necessary, but it is also extremely difficult to extract the polymer in the form of fine particles from an aqueous emulsion because it involves aggregation, coalescence, etc. of the polymer particles. Therefore, a method of directly polymerizing AN-based monomers in an organic solvent is desired, but in general, AN-based polymers have strong cohesive forces between polymer particles, so when polymerized according to the usual method, the resulting polymer Particles coalesce,
These aggregate particles become coarse and bulky, and such aggregate particles can no longer be separated into individual fine particles by other mechanical means, resulting in a fine and uniform organic solvent dispersion of AN polymer. That was extremely difficult. In order to overcome these problems, for example, in Japanese Patent Publication No. 45-34396, an oil-soluble polymer substance is added as a dispersant to increase the viscosity of the polymerization system, thereby preventing the aggregation and coalescence of AN polymer particles. Although measures have been proposed, the effect of preventing agglomeration by such measures is not sufficient, and the necessity of adding a large amount of an oil-soluble polymer substance imposes considerable practical limitations. Furthermore, in Japanese Patent Publication No. 51-8127, it was proposed to use a monohydric alcohol having 1 to 4 carbon atoms as an organic solvent.
In this method, not only the type of solvent used is limited, but also the effect of stabilizing uniform dispersion is insufficient, and the publication also states that particles settle to the bottom of the container during storage. Under these circumstances, the present inventors conducted intensive research to industrially advantageously produce a uniform, fine, and stable organic solvent dispersion of AN-based polymers, which had traditionally been considered difficult. in the presence of union
By polymerizing AN in an organic solvent that dissolves AN but not PAN, and which can dissolve or finely disperse the homopolymer of the main component of the specific copolymer, Agglomeration and coalescence are significantly prevented, resulting in uniform fineness and excellent storage stability.
The present invention was achieved by discovering the fact that it is possible to directly produce an organic solvent dispersion of an AN-based polymer. That is, an object of the present invention is to provide an industrially advantageous method for producing an organic solvent dispersion of an AN polymer having a uniform fine particle size and excellent storage stability. Provides a method for producing an organic solvent dispersion of AN-based polymer fine particles that can be applied without any restrictions to various fields of use, such as modifiers for plastics, fibers, films, etc., and surface finishing agents for paper, films, leather, etc. There is a particular thing. The object of the present invention is to use AN alone or a monomer mixture (hereinafter referred to as
AN-based monomer) is polymerized in an organic solvent that dissolves AN, but not PAN, and that can dissolve or finely disperse a long-chain alkyl (meth)acrylate homopolymer represented by the general formula below. This can be achieved industrially advantageously by polymerizing in the presence of a copolymer consisting of 50% by weight or more and 85% by weight of a long-chain alkyl (meth)acrylate represented by the following general formula and the remainder being AN.

[Formula] (However, X is H or CH ₃ and n is an integer from 12 to 22.) The present invention will be described in detail below, but first the main components
The copolymerization ratio of AN must be set at 60% by weight or more, preferably 70% or more, and even more preferably 80% by weight or more. It becomes impossible to exhibit excellent properties such as hardness, weather resistance, and solvent resistance. Other ethylenically unsaturated compounds to be copolymerized if desired include known unsaturated compounds that can be copolymerized with AN, such as halogens such as vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, and vinylidene bromide. Vinyl chloride and vinylidene halides; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, and their salts; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate , octyl (meth)acrylate, methoxyethyl (meth)acrylate, phenyl (meth)acrylate, cyclohexyl (meth)acrylate, and other acrylic esters and methacrylic esters; methyl vinyl ketone, phenyl vinyl ketone, methyl Unsaturated ketones such as isopropenyl ketone; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; acrylamide and its alkyl substituted products; vinyl Unsaturated sulfonic acids such as sulfonic acid, (meth)allylsulfonic acid, p-styrene sulfonic acid, methacrylic acid sulfoethyl ester, methacrylic acid sulfopropyl ester, 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof; styrene; Styrene and its alkyl or halogen substituted products such as α-methylstyrene and chlorostyrene; Allyl alcohol and its esters or ethers; Basic vinyl compounds such as vinylpyridine, vinylimidazole, and dimethylaminoethyl methacrylate; (meth)acrolein; Examples include vinyl compounds such as vinylidene cyanide, glycidyl methacrylate, and methacrylonitrile. In addition, examples of the dispersion medium, that is, an organic solvent that dissolves AN but not PAN, and which can dissolve or finely disperse the long-chain alkyl (meth)acrylate homopolymer represented by the above general formula, include toluene and xylene. , aromatic hydrocarbons such as ethylbenzene; aliphatic hydrocarbons such as pentane, hexane, heptane, octane; acetate esters such as ethyl acetate, butyl acetate, isopropyl acetate, amyl acetate, ethyl glycol acetate; acetone, methyl ethyl ketone, Examples include ketones such as methyl isobutyl ketone; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve. Next, the copolymer present in the polymerization system, which is a central component of the present invention, contains 50% by weight or more, preferably 60 to 85% by weight of a long-chain alkyl (meth)acrylate represented by the general formula below, and the remainder must be configured with AN.

[Formula] (However, X is H or CH ₃ , and n is an integer from 12 to 22.) When using a copolymer in which the copolymerization ratio of long-chain alkyl (meth)acrylate is less than the lower limit of the present invention This makes it difficult to produce an organic solvent dispersion of an AN-based polymer that has a uniform fine particle size and excellent storage stability, which is the objective of the present invention. Furthermore, if n is less than 12, the dispersion stabilizing effect will be insufficient, resulting in partial contamination of aggregated particles or problems with long-term storage stability, and if n exceeds 22, the copolymerizability decreases rapidly, causing industrial problems. In addition, the copolymer is an essential copolymer component.
It is necessary to contain less than 50% by weight of AN, preferably 15 to 40% by weight, and only with such a copolymer composition can the desired dispersion stabilizing effect be fully exhibited. Note that there is no problem in using a small amount of the ethylenically unsaturated compound as the third component of the copolymer as long as the purpose of the present invention is not impaired. There are no restrictions on the method for producing the copolymer, but if the long-chain alkyl (meth)acrylate homopolymer is polymerized in an organic solvent that can dissolve or finely disperse it, the resulting copolymer will be It is preferable that it is obtained as an organic solvent solution or emulsion and added to the polymerization system in the form of an organic solvent solution or emulsion, since the object of the present invention can be achieved more effectively. In addition, such organic solvents include acetate esters such as ethyl acetate, butyl acetate, isopropyl acetate, amyl acetate, and ethyl acetate glycol; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; aromatic hydrocarbons such as toluene and xylene. ; Examples include aliphatic hydrocarbons such as bentane, hexane, heptane, and octane. The amount of such a copolymer used is 1 to 15% by weight, preferably 2 to 10% by weight based on the total amount of AN monomers.
It is desirable to use % by weight; if it is outside the lower limit of the recommended range, the dispersion stabilizing effect will be insufficient, and if it is outside the upper limit of the range, the formed AN
This may impair the properties of the polymer dispersion liquid or impose restrictions on its use. As a polymerization initiator used in the polymerization of AN monomers, conventionally known oil-soluble radical initiators such as azo compounds and organic peroxides are used. For example, as an azo compound, 2,2'- Azobisisobutyronitrile, 2,2'-azobis(2
-Methyl-valeronitrile) 2,2'azobis(2,4-dimethylbutyronitrile),2,2'-azobis(2-methylcapronitrile),2,2'-
Azobis(2,3,3-trimethylbutyrotrile), 2,2'-azobis(2,4,4-trimethylvaleronitrile), 2,2'-azobis(2,4
-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-ethoxyvaleronitrile), 2,2'-azobis(2,4-dimethyl-4
-n-butoxyvaleronitrile), and examples of organic peroxides include acetyl peroxide, propionyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide,
Diacyl peroxides such as lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, diisopropyl perocasi dicarbonate, di-2-ethylhexyl peroxydicarbonate;
Peroxy esters such as -butylperoxyisobutyrate, t-butylperoxypivalate, t-butylperoxyneodocanoate, and t-butylperoxylaurate can be mentioned. Of course, two or more of the above oil-soluble radical initiators may be used in appropriate combination. In addition, the polymerization temperature varies depending on the type of organic solvent and polymerization initiator used, but
It is desirable to set the temperature within the range of approximately 40 to 100°C. If the temperature is outside the lower limit of this range, the reaction rate will be low and it will be undesirable in terms of productivity and economy.
Moreover, if it exceeds the upper limit, problems such as coloring of the polymer may occur, which is not desirable. Furthermore, although there are no restrictions on the concentration of the AN monomer, from the viewpoint of practical use or the particle size and stability of the produced AN polymer fine particles, it is recommended that the concentration be 10 to 50.
It is desirable to set the amount within a range of 10 to 40% by weight. The reason why the cohesive force between polymer particles is weakened by employing the method of the present invention described above and a stable organic solvent dispersion of AN-based polymer fine particles having a size of substantially less than 1 μm can be obtained has not yet been sufficiently elucidated. However, the copolymer present in a solution or emulsion state in the polymerization system plays a role as a dispersion stabilizer for the AN-based polymer particles produced, or especially the long-chain alkyl (meth) in the copolymer. It is believed that the acrylate chains act as a steric hindrance effect on the cohesive force of the polymer particles. The organic solvent dispersion of AN-based polymer fine particles of the present invention not only has particles that are uniform and fine, but also has a stable dispersion state even during long-term storage even without containing any conventional emulsifiers or dispersants. It also has excellent dispersibility when mixed with pigments, paints, and other polymeric substance solutions.
When applied to various fields of application, the unique and unique properties of AN-based polymers can be effectively expressed. A noteworthy effect of the present invention is that it can be manufactured industrially without the need for any other materials. EXAMPLES The present invention will be described below in more detail with reference to Examples, but the scope of the present invention is not limited in any way by the description of these Examples. Example 1 Stirring blades and cooling condenser attached 2
Using a three-necked flask, polymerization was carried out at 60°C for 6 hours with the charging composition shown in Table 1 below, and a polymer solution of stearyl methacrylate (SMA) and AN (a
~d) were created.

[Table] Next, using the same three-necked flask as above, polymerization was carried out at 60°C for 5 hours with the charging composition shown in Table 2 below.

[Table] Among the obtained AN-based polymer dispersions (~), No.~ according to the present invention was a uniform, low-viscosity dispersion of a polymer of 1μ or less (however, regarding No. Some aggregates were observed), but No. and No. 2 were similar to agglomerated paste-like materials. In addition, although No. had a low viscosity, aggregate particles were mixed in, and some sediment formed at the bottom of the container after being left for one week. Example 2 Polymerization was carried out in the same manner as described in Example 1 using the following charge composition (however, the polymerization temperature was 70°C). AN 180 (g) Methyl acrylate 10 Copolymer solution (c) 50 2,2'-azobisisobutyronitrile 2 Ethyl acetate 758 The resulting dispersion contains fine particles of AN polymer of 1μ or less. The mixture was dispersed in a uniform shape, and no precipitate was observed even after one week of standing. Comparative Example Using a three-necked flask similar to that described in Example 1,
Polymerization was carried out using the following charge composition. SMA 130 (g) AN 70 AVN 4 i-propanol 796 Polymerization temperature x time 60°C x 5 hours Obtained copolymer dispersion (hard to say finely dispersed, it was a suspension of coarse particles) copolymer
Polymerization was carried out in the same manner as in Example 2 except that (c) was used in place of (c). However, when the obtained AN polymer dispersion was observed under a microscope, it was found that aggregate particles of 10μ or more were mixed in. A precipitate was formed after standing for one day and night.

Claims (1)

[Scope of Claims] 1. Acrylonitrile (hereinafter referred to as AN) alone or a monomer mixture of 60% by weight or more of AN and the balance being at least one other ethylenically unsaturated compound is dissolved in polyacrylonitrile, but AN is dissolved therein. (hereinafter referred to as PAN) is a long-chain alkyl (meth)acrylate homopolymer represented by the following general formula that is not dissolved in an organic solvent that can be dissolved or finely dispersed. % or less of a long-chain alkyl (meth)acrylate represented by the following general formula, and the remainder being AN. [Formula] {where, X is H or CH ₃ , and n is an integer from 12 to 22.