JPH03168239A - Resin particle having polar group on surface of particle and production thereof - Google Patents

Abstract

PURPOSE:To obtain resin particles containing a polar group on the surface of particles, having monodisperse particle distribution by subjecting a radically polymerizable monomer and sodium styrenesulfonate to disperse polymerization in a solvent containing a dispersion stabilizer and a polymerization initiator. CONSTITUTION:(A) A radically polymerizable monomer (hydrophobic vinyl aromatic monomer or acrylic monomer) and (B) sodium styrenesulfonate containing <5wt.% inorganic salts as impurities are subjected to disperse polymerization in a solvent which contains (C) a dispersion stabilizer and (D) a polymerization initiator, dissolves the components A and B but not a copolymer thereof to give resin particles which are spherical particles consisting essentially of a copolymer of the components A and b, having 1-20mum average particle diameter, a ratio of particle diameter D25 of 25% volume ratio and particle diameter D75 of 75% volume ratio of 1-1.3 and containing sulfonate group derived from the component B.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to resin particles suitable for use in toners for developing electrostatic images used in electrophotography, or fillers for chromatography, and their production. Regarding the method. In particular, the present invention relates to resin particles having a monodisperse particle size distribution and having polar groups on the surface, and a method for producing the same.

(Prior Art) Toners for developing electrostatic images used in fields such as electrophotography generally consist of resin particles of 5 to 20 μm in which colorants, charge control agents, etc. are dispersed in resin particles for binding. Nigrosine, monoazo dyes, metal complexes of salicylic acid or naphthoic acid, and the like are used as charge control agents for imparting triboelectric charging properties to resin particles. However, most of these charge control agents lack compatibility with resin particles, and therefore are unevenly distributed within the resin particles, making it impossible to obtain uniform triboelectric charging properties. Therefore, there are methods to obtain triboelectric charging properties by mixing a resin having a polar functional group (74 charge control resin) with the binder resin, or by directly adding a monomer having a polar functional group to the binder resin. A method has been proposed in which triboelectric charging properties are obtained by copolymerizing with polymers. It is known that good charging characteristics can be obtained when sodium styrene sulfonate is used as a monomer having a polar functional group.

On the other hand, there is a dispersion polymerization method as a method for obtaining spherical resin particles. According to the dispersion polymerization method, it is possible to easily produce resin particles having a small particle size and a narrow particle size distribution, which are suitable for toners or charge control resins for image forming apparatuses that require high image quality.

When a monomer having a polar group is added as a copolymerization component, resin particles having a polar group on the particle surface can be obtained. Such resin particles are suitably used as toners for developing electrostatic images or charge control resins, and are also preferably used as fillers for chromatography. but,
When dispersion polymerization is carried out by adding the commercially available sodium styrene sulfonate, a problem arises in that the particle size distribution becomes very wide.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to produce resin particles with a monodisperse particle size distribution and having polar functional groups on the surface. and its manufacturing method.

(Means for Solving the Problems) The resin particles having polar groups on the particle surface of the present invention are spherical particles whose main component is a copolymer of at least one radically polymerizable monomer and sodium styrene sulfonate. and the volume average particle size of the particles is 1 to 20 μm, and the ratio D2s/Dys of the volume-based 25% particle size D2S to the volume-based 75% particle size I) vs is 1 to 1.3, The particles have sulfonate groups derived from sodium styrene sulfonate on their surfaces, thereby achieving the above object. moreover,
The method for producing resin particles having a polar group on the particle surface of the present invention is carried out in a solvent containing at least one radically polymerizable monomer, 17 um of sodium styrene sulfonate, a dispersion stabilizer, and a polymerization initiator. The method includes a step of performing dispersion polymerization to obtain resin particles having polar groups on the surface of spherical particles, wherein the inorganic salts contained as impurities in the sodium styrene sulfonate are less than 5% by weight, and the solvent is used in the radical polymerization. The solvent is a solvent that can dissolve the monomer and sodium styrene sulfonate but not the copolymer thereof, thereby achieving the above object.

Here, the volume average particle diameter is the average value of volume-based particle diameters obtained by converting particles into spheres having the same volume.

The volume-based 25% particle size D26 and 75% particle size I)ys are particle sizes that include 25% and 75% of the particles calculated from the larger volume-based particle size. The ratio D2S/D75 of these values represents the degree of dispersion of the particle size distribution, and the closer this value is to 1, the narrower the particle size distribution is.

The radically polymerizable monomers used in the present invention include hydrophobic vinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl diniter monomers, and olefin monomers. etc. are used.

Examples of vinyl aromatic monomers include styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
These include O-, m-, p-chlorostyrene, p-ethylstyrene, and divinylbenzene. Examples of the acrylic monomer include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, and 2-methacrylate.
-ethylhexyl, ethyl β-hydroxyacrylate,
γ-hydroxyprobyl acrylate, σ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate,
Examples include ethylene glyfur dimethacrylate. Vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, and the like. Examples of vinyl ether monomers include vinyl n-7 tyl ether, vinyl phenyl ether, and vinyl hexane ether. Examples of olefinic monomers include ethylene, propylene, isobutylene, butene-11, pentene-1,
Examples include 4-methylbentene-1. Two or more of these monomers may be used in combination.

The sodium styrene sulfonate used in the present invention is
The amount of inorganic salts contained as impurities is less than 5% by weight.

Sodium styrene sulfonate is a highly polymerizable monomer and easily polymerizes and hardens at room temperature. Generally commercially available sodium styrene sulfonate contains about 7% by weight of inorganic salts in order to prevent such polymerization reactions. In the method of the present invention, commercially available sodium styrene sulfonate is purified and used with an inorganic salt content of less than 5% by weight. As a result, resin particles having a monodisperse particle size distribution can be obtained. Any known method can be used to purify sodium styrene sulfonate. For example, a method can be used in which commercially available sodium styrene sulfonate is dissolved in an alcohol such as methanol, ethanol, isopropanol, etc., and reprecipitated with a suitable precipitant. Sodium styrene sulfonate is o. Preferably, it is used in a proportion of ot-to weight %.

Examples of dispersion stabilizers include polymeric dispersion stabilizers that are soluble in the above mixed solvents, such as polyacrylic acid, polyacrylates, polymethacrylic acid, polymethacrylates, (meth)
Acrylic acid-(meth)acrylic acid ester copolymer, acrylic acid-vinyl ether copolymer, monostyrene methacrylate copolymer, carboxymethylcellulose, polyethylene oxide, polyacrylamide, methylcellulose, ethylcellulose, hydroxyethylcellulose,
Polyvinyl alcohol and the like are preferred. Nonionic or anionic surfactants can also be used. The dispersion stabilizer is added in an amount of 0.1 to 20% by weight, particularly preferably 1 to 10% by weight, based on the monomers.

As the polymerization initiator, a well-known hydrophobic polymerization initiator is used. Azo compounds such as azopisisobutyronitrile;
Peroxides such as cumene hydroperoxide, di-t-butyl peroxide, benzoyl peroxide, and lauroyl peroxide are used. Although the amount of the polymerization initiator is not particularly limited, it is generally 0.1 to 10% by weight based on the monomer. It is also possible to initiate polymerization using γ-rays or accelerated electron beams without using such an initiator. Alternatively, polymerization may be initiated by combining ultraviolet rays and various photosensitizers.

The solvent used in the dispersion polymerization reaction is a solvent that can dissolve the above-mentioned radically polymerizable monomer and sodium styrene sulfonate, but does not dissolve these copolymers. Such solvents include lower alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone, and methyl butyl ketone; ethers such as tetrahydrofuran and dioxane; esters such as ethyl acetate; dimethyl formamide Amides such as are used. This organic solvent is appropriately selected depending on the type of monomer used. The amount of the solvent to be used is preferably 100 to 1000 parts by weight, more preferably 150 to 750 parts by weight, based on the total weight of floO of the above monomers.

According to the method of the present invention, resin particles having polar groups on the particle surface are produced, for example, as follows. The above radically polymerizable monomer, sodium styrene sulfonate, dispersion stabilizer, and polymerization initiator are dissolved or dispersed in a solvent to perform dispersion polymerization.

A coloring agent may be added to the reaction system for the purpose of coloring the resin particles. As the colorant, for example, dyes, organic pigments, and inorganic pigments are used.

A reaction solution containing the above monomers, dispersion stabilizer, polymerization initiator, solvent, and colorant if necessary was mixed at 40°C to 90°C.
Polymerization is carried out at a temperature of 1 to 50 hours while keeping the system uniform by gentle stirring. At this time, it is preferable to replace the inside of the reaction system with an inert gas in order to suppress the polymerization termination reaction caused by oxygen.

When the obtained polymer is filtered, washed with water or an appropriate solvent as necessary, and dried, the volume average particle size is 1 to 20 μm.
5 Particularly preferably 5 to lOμm, and D25/
Resin particles having a DT5 of 1 to 1.3 and a monodisperse particle size distribution are obtained. This particle has a sulfonate group on the particle surface.

In the dispersion polymerization method of the present invention, the monomer containing sodium styrene sulfonate is dissolved in the solvent, so at the initial stage of polymerization, the reaction proceeds as solution polymerization, and as the molecular weight of the polymer increases, the polymer dissolves in the solvent. They cannot be dissolved in each other, and they tend to collect together and precipitate. Since a dispersion stabilizer is present in the reaction system, the aggregated polymer forms relatively stable dispersed particles. Unreacted monomers are incorporated into these particles together with the polymer, and the polymerization reaction proceeds further. Due to the difference in solubility of monomers in solvents,
It is believed that the hydrophobic monomer is relatively incorporated into the particles and polymerized, and the sodium styrene sulfonate having a polar sulfonate group is polymerized near the surface of the particles.

Therefore, the resin particles obtained by the method of the present invention have polar groups on the particle surface. Furthermore, since the method of the present invention uses sodium styrene sulfonate containing less than 5% by weight of inorganic salts, the volume average particle size is 1 to 20 μm, and D25/Di
The resulting resin particles have an extremely monodisperse particle size distribution with s of 1 to 1.3.

The resin particles thus obtained can be suitably used as a toner for developing electrostatic images or a filler for chromatography. In particular, when used as a toner for developing electrostatic images, it has excellent triboelectric charging properties, small particle size, and monodisperse particle size distribution, so it can be used as a toner for high-quality image forming devices that require high resolution. suitable.

(Example) The invention will now be described with reference to examples.

Length 1'' Mouth 2 (A) Purification of sodium styrene sulfonate Sodium styrene sulfonate (Subiru 7 manufactured by Toyo Soda Kogyo Co., Ltd.)
- 200 g of NaSS), 200 g of water, and 5 g of sodium hydroxide for inhibiting polymerization were placed in an IL flask, and stirred at 70"C at a stirring speed of 30 rpm.
After aging for an hour, it was cooled to 30'C. This was filtered and dried to obtain purified sodium styrene sulfonate. The yield was about 85%. Table 1 shows the composition of inorganic salts contained in sodium styrene sulfonate before and after purification.
It was shown to.

Table 1 (B) Synthesis of resin particles 3 g of methyl acrylate-methacrylic acid copolymer was dissolved in a mixed medium of 225 g of isopropyl alcohol and 15 g of water, and 55 g of styrene, 5 g of butyl acrylate, and 1 g of the purified butyl acrylate were added to the mixture. Sodium styrene sulfonate 0
．． 1 g and 2.5 g of azobisin butyronitrile were added, and the mixture was heated at 50 r under a nitrogen atmosphere in a 14 separable flask.
The polymerization was completed by reacting for 12 hours at 70"C with stirring at pm. The emulsion was filtered, washed and dried to obtain a white powder.

The particle size of the particles is shown in Table 2, and the particle size distribution is shown in FIG.

Table 2 Volume average particle diameter Dsa 7.54 μm volume standard 2
5% particle size D2S L71μm volume basis 75% particle size 0
75 6. 95μ habituation D 25/D vs
1. 25 the above polymer particles 50i,
Azo black disperse dye (Mitsui Toatsu Dye Co., Ltd. M S
6 g of PR Black #200) and an aqueous dispersion stabilizer were dispersed in so much water, placed in a 1-liter flask, and dyed at 85° C. for 5 hours with stirring. This was filtered, washed and dried to obtain black particles.

A developer with a toner concentration of 2vt% was prepared by mixing and stirring the above black polymer particles and farite beef Yasoa, and when the band TiII was measured by the blow-off method, -2
It was 1.3 μC/g. When a copying test was carried out using this developer in a DC-12 (15 manufactured by Sanda Kogyo ■), clear images were obtained, and the resolution was 6 lines/rm.

Mainly red (A) Purification of sodium styrene sulfonate Sodium styrene sulfonate (Subiru 7 manufactured by Toyo Soda Kogyo Co., Ltd.)
-NaSS), 100 g of water, and 5 g of sodium hydroxide for inhibiting polymerization were put into an IL flask, and the mixture was aged at 70"C for 1 hour at a stirring speed of 300 rpm, and then cooled to 30"C. This was filtered and dried to obtain purified sodium styrene sulfonate. The yield was about 97%. Table 3 shows the composition of inorganic salts contained in sodium styrene sulfonate before and after purification.

Table 3 Inorganic salts Unpurified products Purified products (8) Synthesis of resin particles Polymer particles were synthesized in the same manner as in Example 1 using the above sodium styrene sulfonate.

The diameter of the particles is shown in Table 4, and the particle size distribution is shown in FIG.

Furthermore, a copying test was conducted using the black polymer particles obtained by coloring in the same manner as in Example 1.
A clear image similar to that was obtained.

Table 4 Volume average particle diameter Dsa? , 67 μm volume standard 2
5% particle size D21) 9.08μm Volume based 75% particle size D75 L98μrnD 25/ D ts
1. Up to 30 Motoe LL Implemented except that unpurified sodium styrene sulfonate was used as is (R Polymer particles were synthesized in the same manner as in 1. The particle size of the produced particles is shown in Table 5, and the particle size distribution was Shown in the figure.

Table 5 Volume average particle diameter D s@6. 79μ theoretical volume basis $25% particle size 0 26 g. 53μ1 Volume based 75% particle size D 75 5. 04μ Otori D2s/
D completed 1. 58 The above particles were dyed in the same manner as in Example 1 and subjected to a copying test. The resolution of the obtained image was degraded to 4 lines/III1.

(Effects of the Invention) As described above, the resin particles of the present invention have polar sulfonate groups on the particle surface, have a volume average particle diameter in the range of 1 to 20 μm, and have a monodisperse particle size distribution. . Therefore, it can be suitably used as a toner for developing electrostatic images or a filler for chromatography.

Furthermore, according to the method of the present invention, resin particles having such excellent properties can be easily produced.

4. of. What! I FIG. 1, FIG. 2, and FIG. 3 are diagrams showing the particle size distribution of resin particles obtained in Examples 1 and 2 and Comparative Example 1.

that's all

Claims (1)

[Scope of Claims] 1. Spherical particles mainly composed of a copolymer of at least one radically polymerizable monomer and sodium styrene sulfonate, the particles having a volume average particle diameter of 1 to 20 μm. and the volume-based 25% particle size D_2_5 and the volume-based 75% particle size D_7_5
The ratio D_2_5/D_7_5 is 1 to 1.3, and the particle surface has a sulfonate group resulting from sodium styrene sulfonate.Resin particles having a polar group on the particle surface. 2. Perform dispersion polymerization in a solvent containing at least one radically polymerizable monomer, sodium styrene sulfonate, a dispersion stabilizer, and a polymerization initiator to obtain resin particles having polar groups on the spherical particle surface. the sodium styrene sulfonate contains less than 5% by weight of inorganic salts as impurities, and the solvent is capable of dissolving the radically polymerizable monomer and the sodium styrene sulfonate; A method for producing resin particles having polar groups on the particle surface, which is a solvent that does not dissolve coalescence.