JPH0745523B2 - Method for producing monodisperse fine particle copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a monodisperse fine particle copolymer.

BACKGROUND ART Conventionally, emulsion polymerization is a method in which oil droplets are formed and reacted in an aqueous medium using an emulsifying agent.However, since the emulsifying agent becomes an impurity in the resulting polymer, it has hitherto been performed without using an emulsifying agent. Alternatively, a monodispersed fine particle polymer or copolymer is produced by copolymerization. Thus, polymerization or copolymerization without using an emulsifier, in the so-called soap-free polymerization or copolymerization, as a monomer,
In order to emulsify and stabilize oil droplets during polymerization, a monomer having a reactive or emulsifying action is used.

Problems to be Solved by the Invention However, since the monomers used in conventional soap-free polymerization or copolymerization are hydrophilic compounds, the properties of the resulting polymer or copolymer are environmentally dependent. However, there is a drawback that the dependency on humidity is particularly high.

The present invention has been made in view of such problems in the conventional technique.

An object of the present invention is to provide a method for producing a monodisperse fine particle copolymer which has excellent properties by soap-free copolymerization and can be used in various applications, particularly in an electrophotographic developer.

Means for Solving the Problems As a result of various studies, the present inventors have found that when a certain kind of hydrophobic monomer is used as a copolymerization component, the copolymerization can be carried out in an aqueous medium without using an emulsifier. They found that it is possible, and completed the present invention.

The method for producing the monodisperse fine particle copolymer of the present invention has a vinyl-based monomer and a critical surface tension of 40 dynes or less,
It is characterized in that a hydrophobic vinyl monomer containing a Si atom is dispersed in an aqueous solvent and copolymerized without using an emulsifier.

Hereinafter, the present invention will be described in detail.

In the present invention, as the vinyl-based monomer used as a raw material, styrene and its derivatives, for example, chlorostyrene, methylstyrene, α-methylstyrene, etc., acrylic and methacrylic acid esters, for example, methyl acrylate, methyl methacrylate, ethyl. Examples thereof include acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, phenyl acrylate and phenyl methacrylate. Furthermore, as nitrogen-containing monomers, acrylic monomers such as diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate,
N-substituted maleimides such as N-phenylmaleimide, N-methylphenylmaleimide, N-chlorophenylmaleimide, N-methoxyphenylmaleimide and N-laurylmaleimide, and 4-vinylpyridine and 2-vinylpyridine can be used.

On the other hand, the hydrophobic vinyl monomer copolymerized with the vinyl-based monomer is one of the features of the present invention, and has a critical surface tension of 40%.
It has dyne or less and contains a Si atom in the molecule.
Examples of such a hydrophobic vinyl monomer include those having the structural formulas shown below.

In the present invention, the value of the critical surface tension is a value measured by a surface tension measuring device (Kyowa Interface Chemistry CBVP-A3).

In the present invention, in addition to the above monomers, known polyfunctional monomers such as divinylbenzene and diethylene glycol methacrylate may be added as a crosslinking agent.

Having a vinyl monomer and a critical surface tension of 40 dynes or less,
The polymerization reaction with the hydrophobic vinyl monomer containing a Si atom in the molecule is performed in an aqueous medium by a known method. For example, copolymerization is carried out by using a polymerization initiator under a ratio of monomer to water of 10:90 to 45:55 (volume ratio), for example, an aqueous solution concentration.
Add it so that the concentration is 10 ^{-5 to} 5 × 10 ^-2 mol /
The reaction can be carried out at -80 ° C for 5-45 hours. As the polymerization initiator, known ones can be used, for example, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis (N, N′-dimethyleneisobutyramidine) hydrochloric acid. Salts, ammonium persulfate, potassium persulfate and the like can be advantageously used.

The copolymerization ratio of each monomer is appropriately selected according to the purpose.

After completion of the polymerization, the copolymer is centrifuged from the reaction solution and freeze-dried to solidify.

The polymer produced in the present invention has a three-dimensional structure in which silicon atoms are crosslinked by siloxane bonds.

EXAMPLES Hereinafter, the present invention will be described by way of examples. In the following examples, the molecular weight was measured using HLC-802A (manufactured by Toyo Soda Co., Ltd.). That is, the copolymer fine powder of the present invention was dissolved in tetrahydrofuran to a concentration of 0.5%, and RI was passed through a GMH6 column (Toyo Soda Co., Ltd.).
Detected by.

The glass transition point (Tg) was measured by using Shimadzu DT-40 (manufactured by Shimadzu Corporation) as a measuring instrument. Polymer fine powder was placed in an aluminum cell (reference cell was empty cell) and the temperature was raised at a rate of 10 ° C / min. It was warmed and the rising point of the endotherm was measured as Tg.

The infrared absorption spectrum was measured using Hitachi 270-30 (manufactured by Hitachi, Ltd.) by compression molding fine polymer powder together with KBr.

Example 1 Water was added to 10 glass reactors equipped with an inclined paddle type stirring blade, a nitrogen inlet, a temperature controller and a monomer dropping funnel.
After charging 00 ml and replacing with nitrogen gas, the temperature was raised to 60 ° C. The rotation speed of the stirring blade was adjusted to 250 rpm. Then, in the dropping funnel, as a monomer, a mixed liquid of 630 g of styrene and 70 g of a silicon-containing vinyl monomer represented by the following structural formula (SZ-6032 manufactured by Toray Silicone Co., Ltd.) was charged and set in a reactor. .

After confirming that the temperature became constant, 100 ml of an aqueous solution containing 5.7 g of V-50 (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization disclosure agent
Was added, and subsequently, a mixed solution of the above monomers was added dropwise. Polymerization starts from the time when the dropping of the mixed liquid of the monomers is started.
It lasted 24 hours. After completion of the polymerization reaction, a part of the emulsion was centrifuged and dried for identification. The analysis results of this product are as follows.

Glass transition point: 100 ° C Elemental analysis value H: 7.73% C: 90.82% N: 0.39% Particle size: 0.2 μm (scanning electron microscope) Particle size distribution: Almost monodisperse The obtained copolymer was tetrahydrofuran, toluene,
It was insoluble in dichloromethane and methyl ethyl ketone.
The Si element was confirmed by the ESCA spectrum of this product. The infrared absorption spectrum was as shown in FIG.

Example 2 Into a separable flask 1 equipped with a reflux condenser, a nitrogen inlet, a stirring blade (paddle type), a monomer charging port, and a temperature controller, 580 ml of distilled water was charged and replaced with nitrogen gas. 6
The temperature was raised to 0 ° C.

Styrene 71.25g and aminosilicone monomer 9.37g (Toray Silicone Co., Ltd., SZ6032, 40%)
The mixed solution of (methanol solution) was placed in a dropping funnel. On the other hand, 0.6 g of a polymerization initiator (V-50 manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 20 g of distilled water. Immediately after placing this aqueous solution in the flask, the dropping of the mixed liquid of the monomers was started. 60 drops
The reaction was completed in minutes, and the polymerization reaction was continued for another 18 hours.

Then, the polymerization reaction liquid was subjected to ultrafiltration and freeze-dried to obtain a copolymer. The analysis results of this product are as follows.

Particle size: 0.2 μm (scanning electron microscope) Glass transition point: 96 ° C. This copolymer had a large amount of gel, and the molecular weight could not be measured.

Effect of the Invention As described above, the present invention uses a hydrophobic vinyl monomer having a critical surface tension of 40 dynes or less and containing a Si atom in a molecule, and copolymerizes in an aqueous solvent without using an emulsifier. From the above, the properties of the obtained monodisperse fine particle copolymer have low environmental dependency, particularly low dependency on humidity. Therefore, when the copolymer obtained by the present invention is used as an additive for an electrophotographic developer, The triboelectric chargeability and fluidity of the electrophotographic developer are improved.

[Brief description of drawings]

FIG. 1 is a graph of infrared absorption spectrum of a silicon-containing vinyl polymer produced according to the present invention.

Claims (3)

[Claims] 1. A vinyl-based monomer and a hydrophobic vinyl monomer having a critical surface tension of 40 dynes or less and containing a Si atom in the molecule are dispersed in an aqueous solvent without using an emulsifier, A method for producing a monodisperse fine particle copolymer, which comprises polymerizing. 2. The method for producing a monodisperse fine particle copolymer according to claim 1, wherein the vinyl-based monomer is styrene or a derivative thereof, an acrylic acid ester or a methacrylic acid ester. 3. The monodisperse product according to claim 1, wherein the hydrophobic vinyl monomer having a critical surface tension of 40 dynes or less and containing a Si atom in the molecule is a compound represented by the following structural formula. Method for producing fine particle copolymer.