JPH06116308A - Manufacturing method of polymer particles - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for stably and efficiently producing fine particles of a fatty acid vinyl ester polymer having a narrow particle size distribution in the order of submicron to micron. [Structure] Vinyl ester of fatty acid having 4 or less carbon atoms,
Polymerization is carried out in an organic solvent that dissolves the vinyl ester and does not dissolve the resulting polymer, using a polymer composed of vinyl ester units of a fatty acid having 5 or more carbon atoms as a dispersion stabilizer. A method for producing fine particles of a fatty acid vinyl ester polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polymer fine particles, and more specifically, by using a specific dispersion stabilizer, fine particles of fatty acid vinyl ester polymer having a narrow particle size distribution in the submicron to micron order. To a stable and efficient method for producing

[0002]

2. Description of the Related Art In various fields such as toners used for electrophotography, electrostatic photography, electrostatic recording, carriers for column chromatograms, cosmetic powders and paints for blocking ultraviolet rays, and medical clinical diagnosis. It is strongly desired that polymer fine particles of submicron to micron order, especially 0.1 to 30 micron and narrow particle size distribution are suitable.

[0003] Conventionally, it has been studied to produce polymer particles used for these applications by an emulsion polymerization method, a seed emulsion polymerization method, and a suspension polymerization method. However, the emulsion polymerization method has a problem that only polymer particles of 1 micron or less can be obtained. The seed emulsion polymerization method produces particles having a narrow particle size distribution on the order of microns (for example, JP-A-58-106554). After the fine particles are first prepared, in order to increase the particle size, it is necessary to further grow the particle size by polymerization in the next several steps, and the operation is extremely complicated. Further, the suspension polymerization method can only give particles having a large particle size, and the particle size distribution is wide.

On the other hand, J. Polym. Sci. Polym. Chem. Ed. Vol. 24, p.299 has been proposed as a method for obtaining monodisperse polymer particles of submicron to micron order by one-step polymerization.
5 to 3007 (1986), a method of dispersion polymerization in an organic solvent system is introduced. In this method, the monomer is dissolved in an organic solvent in which the monomer is dissolved but the polymer produced is not dissolved, and polymerization is carried out to obtain polymer fine particles. Further, in Polymer 40, No. 4, p.240-243 (1991), vinyl acetate was polymerized in a hydrocarbon medium in the presence of a medium-soluble poly (n-dodecyl methacrylate) to give 0.05-0.3. An example in which almost monodisperse fine particles in the range of μm are synthesized and an example in which vinyl acetate is polymerized in the presence of poly (2-ethylhexyl methacrylate) are introduced.

[0005]

Dispersion polymerization using the above organic solvent gives fine polymer particles having a uniform particle size of submicron to micron order, but narrow polymerization conditions are set to control the particle size. It has the drawback of having to do it. In addition, there is a problem that the obtained polymer fine particles have a broad particle size distribution.

An object of the present invention is to provide a method for stably and efficiently producing monodisperse fatty acid vinyl ester polymer fine particles having a particle size of submicron to micron order and having an extremely narrow particle size distribution. Especially.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies to develop a method for producing polymer fine particles which is easy to control the particle size and particle size distribution and has excellent polymerization stability. As a result, they have found that the above object can be achieved by using a polymer composed of vinyl ester units of fatty acids having 5 or more carbon atoms as the dispersion stabilizer. The present invention has been completed based on these findings.

That is, according to the present invention, a vinyl ester of a fatty acid having 4 or less carbon atoms is converted into a vinyl ester unit of a fatty acid having 5 or more carbon atoms in an organic solvent which dissolves the vinyl ester and does not dissolve the resulting polymer. It is intended to provide a method for producing fine particles of a fatty acid vinyl ester polymer, which is characterized in that polymerization is carried out by using a polymer as a dispersion stabilizer.

In the method of the present invention, the monomer to be polymerized (raw material monomer) is a vinyl ester of a fatty acid having 4 or less carbon atoms, and specific examples thereof include vinyl formate, vinyl acetate and propionic acid. Examples thereof include vinyl and vinyl butyrate. These may be used alone or in combination of two or more, and among these, vinyl acetate is most preferable. It is also possible to add a small amount of another monomer to the raw material vinyl ester for copolymerization, but in that case, the vinyl ester is dissolved in the organic solvent used in the present invention, which is the gist of the present invention. In addition, it is important that the resulting polymer is not dissolved in an organic solvent, and the content of such other monomer is 30% by weight or less, more preferably 20% by weight or less. Specific examples of such a monomer include, for example, vinyl valerate, vinyl pivalate,
Vinyl esters of fatty acids having 5 or more carbon atoms such as vinyl 2-ethylcaproate, vinyl caprate, vinyl laurate, vinyl versatate, and vinyl stearate; α-olefins such as ethylene and propylene, (meth) acrylic acid, Carboxylic acid-containing monomers such as itaconic acid, maleic acid and crotonic acid, and anhydrides or esters thereof; dimethylacrylamide, N-vinyl-2-pyrrolidone,
Examples thereof include acryloylmorpholine, N, N-dimethylaminoethyl (meth) acrylate, and vinyl halides such as vinyl chloride and vinyl fluoride. Further, it is also possible to coexist a compound having two or more polymerizable double bonds in the molecule for the purpose of introducing cross-linking into the obtained polymer fine particles, and specific examples of such a compound include: For example, divinyl ether, diallyl ether, diallyl phthalate, vinyl crotonic acid, vinyl maleate, divinyl maleate, diallylamine, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, butylene glycol (meth) acrylate, glycerin di (meth) ) Acrylate, glycerin tri (meth) acrylate, triallyl isocyanurate and the like.

Further, the organic solvent used in the method of the present invention is an organic solvent in which a vinyl ester of a fatty acid having 4 or less carbon atoms is dissolved but a polymer produced is not dissolved. Specifically, for example, n-pentane is used. , N-hexane, n-octane, n-decane, n-dodecane, n-tridecane,
Linear hydrocarbons such as n-tetradecane; branched hydrocarbons such as 2-methylpentane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; petroleum ether, gasoline, kerosene, n-paraffin, liquid paraffin, petroleum benzine. And the like; ethers such as diethyl ether, and the like. You may use these organic solvents individually or in mixture of 2 or more types. Furthermore, it is possible to add a small amount of other organic solvent or water depending on the purpose,
Specific examples of such an organic solvent include alcohols such as methyl alcohol and ethyl alcohol; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; ethylene glycol monomethyl ether and ethylene glycol mono. Ether alcohols such as ethyl ether and ethylene glycol monobutyl ether; tetrahydrofuran, dimethoxyethane, dimethyl sulfoxide, N, N-dimethylformamide and the like. Further, in the method of the present invention, the mixing ratio of the organic solvent and the vinyl ester as a raw material may be appropriately selected according to various situations, but usually, the organic solvent / vinyl ester (weight ratio) = 60/40. ~ 9
5/5, preferably 70/30 to 90/10.

The dispersion stabilizer used in the method of the present invention is a polymer (homopolymer or copolymer) composed of vinyl ester units of fatty acids having 5 or more carbon atoms.
The dispersion stabilizer used in the present invention dissolves in the organic solvent used and functions as a protective colloid for the resin particles produced.

The vinyl ester of a fatty acid having 5 or more carbon atoms is not particularly limited as long as it is a vinyl ester of a fatty acid having 5 or more carbon atoms, and specific examples thereof include vinyl valerate, vinyl pivalate and vinyl caproate. , 2-ethyl caproate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate and the like. The dispersion stabilizer of the present invention comprises a polymer composed of vinyl ester units of the above fatty acids having 5 or more carbon atoms, but is in the range where the compatibility with the solvent used in the present invention is not lost (specifically, 30 (Small amount less than weight%)
It is also possible to contain other components in. Specific examples of such other components include, for example, α-olefins such as ethylene and propylene; carboxylic acid-containing monomers such as (meth) acrylic acid, itaconic acid, maleic acid, and crotonic acid, and anhydrides thereof. Ester; dimethylacrylamide, N-vinyl-2-pyrrolidone, acryloylmorpholine, N, N-dimethylaminoethyl (meth) acrylate; units derived from vinyl halides such as vinyl chloride and vinyl fluoride.

The molecular weight of the dispersion stabilizer is not particularly limited, and its preferred range varies depending on various circumstances, but the number average molecular weight is usually 5,000 to 200,000, preferably 7,000 to 100,000. When the number average molecular weight is less than 5,000, the role of the produced polymer as a protective colloid is not sufficiently exhibited, and when it exceeds 200,000, problems may occur during production of the dispersion stabilizer.

In the method of the present invention, the amount (mixing ratio) of the dispersion stabilizer is not particularly limited and may be appropriately determined according to various situations, but usually 100 parts by weight of the vinyl ester as a raw material. On the other hand, it is selected in the range of 0.5 to 25 parts by weight, preferably 2 to 15 parts by weight.

The dispersion stabilizer used in the present invention is usually obtained by radical polymerization of vinyl ester of fatty acid having 5 or more carbon atoms. The polymerization can be produced by conventionally known bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, or the like.

In the method of the present invention, the vinyl ester is polymerized in the presence of the above-mentioned dispersion stabilizer. In this case, it is preferable to use a polymerization initiator. However, it is also possible to initiate the polymerization by irradiation with an active energy ray such as radiation without using a polymerization initiator. When a polymerization initiator is used, the type of the polymerization initiator is not particularly limited as long as it is soluble in the solvent used, and specifically, for example, benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide. Common radical initiators such as can be used. The mixing ratio of the polymerization initiator is not particularly limited, but generally, with respect to 100 parts by weight of the vinyl ester as a raw material,
It is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight. When a polymerization initiator having a short half-life is used, it may be added all at once at the beginning of the polymerization or may be added later at an appropriate interval (delay addition). In carrying out the method of the present invention, the reaction temperature is appropriately set depending on the particle size of the target polymer particles, but it is generally -50 to 90.
℃, preferably set in the range of -30 to 75 ℃.

An example of the manufacturing process in the method of the present invention will be briefly described as follows. That is, a solvent was charged in a polymerization tank equipped with a stirrer, a reflux condenser, and a nitrogen introducing device, and then the above-mentioned dispersion stabilizer was added, and the nitrogen was sufficiently replaced with stirring, followed by heating to a predetermined temperature for dispersion. Dissolve the stabilizer. Then, a predetermined amount of vinyl ester and a polymerization initiator are added to start the polymerization reaction. The resulting polymer forms particles, and the particle size increases with the polymerization rate.
After carrying out the polymerization for a predetermined time, it is cooled to stop the polymerization reaction. The obtained polymer fine particles are washed and dried after draining. For the operation after the polymerization, various methods such as repeated washing and freeze-drying can be adopted.

According to the method of the present invention, the average particle size is 0.1-0.1.
Polymer fine particles having a particle size of 30 μm, preferably 0.1 to 10 μm and a variation coefficient (standard deviation / average particle size × 100) of 25% or less are easily obtained. In carrying out this method, an organic or inorganic pigment such as carbon black or silica, waxes, a monomer having a dye structure, or the like may be appropriately added and polymerized. Further, in the method of the present invention, a dispersion stabilizer can be sufficiently obtained by using a polymer composed of vinyl ester units of a fatty acid having 5 or more carbon atoms alone as a dispersion stabilizer. Other soluble polymers may be used together as a dispersion stabilizer.

[0019]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" are based on weight unless otherwise specified. Example 1 A 500 milliliter glass separable flask equipped with an inclined paddle stirrer, a thermometer, a nitrogen inlet, a monomer charging port and a reflux condenser was charged with n-hexane 3 as a solvent.
Then, 00 milliliter was charged, 2.14 g of vinyl versatate having a number average molecular weight of 29000 was charged, and the atmosphere was sufficiently replaced with nitrogen, and then the internal temperature was raised to 70 ° C. Vinyl acetate 4
A mixed solution of 3 g and azobisisobutyronitrile 0.26 g as a polymerization initiator was added, and polymerization was initiated at 60 ° C. 0.13 g of azobisisobutyronitrile was added 4 hours and 7 hours after the initiation of the polymerization. The polymerization was continued for a total of 12 hours and then cooled. When the number average particle diameter, standard deviation and coefficient of variation of the obtained polymer fine particles were measured using an electrophoretic light scattering photometer (ELS-800 manufactured by Otsuka Electronics Co., Ltd.), the number average particle diameter was The standard deviation was 0.56 μm, the standard deviation was 0.070 μm, and the coefficient of variation was 12.5%.

Example 2 Instead of the polymer used in Example 1, a number average molecular weight of 42
When a dispersion polymerization reaction of vinyl acetate was carried out in the same manner as in Example 1 except that 2,000 polyvinyl pivalate was used, the number average particle diameter of the obtained polymer fine particles was 0.
The standard deviation was 49 μm, the standard deviation was 0.097 μm, and the coefficient of variation was 19.8%.

Example 3 Instead of the polymer used in Example 1, a number average molecular weight of 140
Example 1 except that the vinyl polylaurate of No. 00 was used.
When dispersion polymerization of vinyl acetate was carried out in the same manner as
The number average particle diameter of the obtained polymer fine particles is 0.45 μm,
Standard deviation is 0.074 μm and coefficient of variation is 16.4%
Met.

Example 4 Dispersion polymerization of vinyl acetate was carried out in the same manner as in Example 1 except that polyvinyl polycaprate was used instead of the polymer used in Example 1 to obtain the polymer. The number average particle diameter of the fine particles is 0.53 μm, and the standard deviation is 0.088 μm.
And the coefficient of variation was 16.6%.

Example 5 Dispersion polymerization of vinyl acetate was carried out in the same manner as in Example 1 except that vinyl polycaproate was used in place of the polymer used in Example 1 to obtain the polymer. The number average particle size of the fine particles is 0.51 μm, and the standard deviation is 0.078 μm.
And the coefficient of variation was 15.3%.

Example 6 The procedure of Example 1 was repeated except that the polymer used in Example 1 was replaced by vinyl poly-2-ethylcaproate.
When dispersion polymerization of vinyl acetate was carried out, the number average particle diameter of the obtained polymer fine particles was 0.50 μm, and the standard deviation was 0.
The coefficient of variation was 094 μm and the coefficient of variation was 18.8%.

Comparative Example 1 A dispersion polymerization of vinyl acetate was carried out in the same manner as in Example 1 except that polylauryl methacrylate having a number average molecular weight of 27500 was used in place of the dispersion stabilizer used in Example 1. The number average particle diameter of the obtained polymer fine particles was 0.57 μm, the standard deviation was 0.15 μm, and the variation coefficient was 26.3%.

Comparative Example 2 A dispersion polymerization of vinyl acetate was carried out in the same manner as in Example 1 except that polystearyl methacrylate having a number average molecular weight of 18,000 was used in place of the dispersion stabilizer used in Example 1. The number average particle diameter of the obtained polymer fine particles was 0.54 μm, the standard deviation was 0.16 μm, and the coefficient of variation was 29.6%.

[0027]

Industrial Applicability According to the method of the present invention, the polymer fine particles obtained have excellent monodispersibility, which is of great industrial significance. Thus, the polymer fine particles obtained by the method of the present invention are polymer fine particles having excellent monodispersity on the order of submicron to micron and are used for electrophotography, electrostatic photography, electrostatic recording and the like. Toner, carrier for column chromatogram, cosmetic powder for UV protection,
It is widely and effectively used in various fields such as paints and medical clinical diagnosis.

Claims (1)

[Claims] 1. A vinyl ester of a fatty acid having 4 or less carbon atoms, which is composed of vinyl ester units of fatty acid having 5 or more carbon atoms, in an organic solvent that dissolves the vinyl ester and does not dissolve the resulting polymer. A method for producing fine particles of a fatty acid vinyl ester polymer, which comprises polymerizing the coalescence as a dispersion stabilizer.