JP2008163082A - Method for producing composite resin particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a composite resin particle by which the production process is simple at a low cost and a smaller resin particle than a matrix is uniformly applied or fixed to the surface of the resin particle to be the matrix. <P>SOLUTION: The method for producing the composite resin particle is characterized by a step of dissolving or dispersing a polymer dispersant and a surfactant in an aqueous medium and forming an aqueous dispersion, a step of dissolving a polymerization initiator in a polymerizable monomer and forming an oil-based dispersion, a step of mixing the aqueous dispersion with the oil-based dispersion and forming an emulsion and a step of heating the emulsion, polymerizing the emulsion and applying or fixing the smaller resin particle (B) than the matrix to the surface of the resin particle (A) to be the matrix. The value of a represented by the following formula 1: a=b<SP>1/2</SP>is 0.2-10 and the ratio b of the polymer dispersant to the polymerizable monomer is 0.002-0.1 mol%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is used for fine particles for electrophotography, gap adjusting agents for liquid crystal display panels, medical diagnostic carriers, standard particles for particle size measurement, chromatography fillers, light diffusing agents, cosmetic fillers, paints, and the like. The present invention relates to a method for producing composite resin particles.

  The conventional method for producing composite particles is to manufacture resin particles that are the base material and resin particles that are smaller than the base material in separate manufacturing processes, and then mix the resin particles that are the base material and resin particles that are smaller than the base material, The resin particles smaller than the base are adhered or fixed to the surface of the base resin particles by a strong force or heating (for example, see Patent Documents 1 and 2), and it is difficult to control the adhesion of the small resin particles to the resin particle surface. There were many processes and the cost was high.

Patent Document 3 discloses a technique for producing small-diameter particles by a method in which an aqueous dispersion and an oil-based dispersion are mixed to form an emulsion, and then heated and polymerized. Particles were made impossible, and small-diameter particles were not uniformly attached to the surface of the resin particles, and the manufacturing process was complicated and expensive.
International Publication No. 03/093353 Pamphlet JP 2006-22176 A Japanese Patent Laid-Open No. 58-2322

  The present invention has been made in view of the above problems, and its purpose is that the manufacturing process is simple, the cost is low, and the resin particles smaller than the matrix are uniformly attached or fixed to the surface of the matrix. Another object is to provide a method for producing composite resin particles.

  The above object of the present invention is achieved by the following configurations.

  1. In the method for producing composite resin particles in which resin particles (B) smaller than the matrix are adhered or fixed to the surface of the resin particles (A) serving as a matrix, the polymer dispersant and the surfactant are dissolved or dissolved in an aqueous medium. A step of dispersing to form an aqueous dispersion, a step of dissolving an initiator in a polymerizable monomer to form an oil-based dispersion, a step of mixing the aqueous dispersion and the oil-based dispersion to form an emulsion, The emulsion is heated and polymerized to attach or fix resin particles (B) smaller than the base to the surface of the base resin particles (A), and the value of a represented by the following formula 1 is 0. The method for producing composite resin particles, wherein the ratio is 2 to 10 and the ratio of the polymeric dispersant to the polymerizable monomer is 0.002 to 0.1 mol%.

Formula 1 a = b ^1/2
However, b represents the mol% of the polymerization initiator with respect to the polymerizable monomer.

  2. In the method for producing composite resin particles in which resin particles (B) smaller than the matrix are adhered or fixed to the surfaces of the resin particles (A) serving as a matrix, a polymer dispersant, a surfactant and a polymerization inhibitor are aqueous A step of forming an aqueous dispersion by dissolving or dispersing in a medium, a step of forming an oil dispersion by dissolving a polymerization initiator in a polymerizable monomer, and mixing the aqueous dispersion and the oil dispersion to form an emulsion. A step of forming, heating and polymerizing the emulsion, and attaching or fixing resin particles (B) smaller than the base to the surface of the base resin particles (A). The composite resin particles are characterized in that the value of the polymer dispersant is 0.002 to 0.1 mol% with respect to the polymerizable monomer of 0.2 to 10 Method.

Formula 2 a = b ^1/2 − (c × d) ^1/2
However, b is mol% of the polymerization initiator with respect to the polymerizable monomer.
c is the volume ratio of the polymerizable monomer to the aqueous medium
d is mol% with respect to the polymerizable monomer of the polymerization inhibitor.
Represents.

  3. It has the process of isolate | separating from the aqueous medium the composite resin particle which adhered or fixed the resin particle (B) smaller than this base material to the surface of the resin particle (A) used as the said base | matrix, and the process of drying. 3. A method for producing composite resin particles according to 1 or 2.

  According to the present invention, it is possible to provide a method for producing composite resin particles in which the production process is simple, the cost is low, and resin particles smaller than the matrix are uniformly attached or fixed to the surface of the matrix resin particles. it can.

  As a result of intensive studies in view of the above problems, the present inventor controls the stability of oil droplets during polymerization when an aqueous dispersion and an oil dispersion are mixed to form an emulsion and heated and polymerized. Thus, it becomes possible to attach or fix resin particles having a particle size smaller than that of the base to the surface of the base resin particles, and by using a polymer dispersant and a surfactant in the aqueous dispersion. The present inventors have found that resin particles serving as a base and resin particles having a particle size smaller than that of the base can be formed, leading to the present invention.

  In the present invention, resin particles smaller than the matrix can be evenly adhered or fixed to the surface of the resin particles serving as the matrix. Conventionally, there has been no example in which the resin particles are uniformly adhered to the surface as in the present invention. In addition, the present invention can produce composite particles in a single process, and it is easy to control adhesion and fixation of small resin particles to the resin particle surface, and can be produced at low cost, and therefore has great industrial value.

  Details of the mechanism by which these effects are manifested are unknown, but are considered as follows.

  Due to the difference in the polymerization reaction mechanism, there is a difference in the formation rate of the resin particles as the base and the resin particles having a smaller particle size than the base, and the formation rate of the resin particles having a smaller particle size than the base is usually higher.

  In addition, resin particles having a smaller particle size are often higher in molecular weight, and thus resin particles having the same composition, high strength, and improved core / shell structure with improved light scattering properties can be formed.

  In order to attach or fix resin particles smaller than the base to the surface of the base resin particles, it is necessary to control the stability of the oil droplets during polymerization. This is a phenomenon that can occur only under very narrow setting conditions, where oil droplets smaller than the base must be stable during polymerization and the base oil droplets need to be slightly unstable during polymerization. .

  In order to achieve this phenomenon, it is important to set the generation rate of resin particles smaller than the base and the polymerization rate of the base, and the value of a expressed by the above formula 1 is 0.2 to 10, The mol% of the molecular dispersant with respect to the polymerizable monomer needs to be 0.002 to 0.1.

  If the value of a is less than 0.2, the adhesion of small-diameter particles becomes non-uniform. If the mol% of the polymeric dispersant with respect to the polymerizable monomer is less than 0.002, the matrix is not stable and particles cannot be formed, and if it is more than 0.1, small particles are often generated and the matrix and small particles are separated. It becomes difficult.

  In the case of using a polymerization inhibitor, a represented by the above formula 2 in which the influence of the polymerization inhibitor is corrected is used instead of the a represented by the above formula 1.

(Polymerizable monomer)
Examples of the polymerizable monomer used in the present invention include styrene monomers such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, chlorostyrene, methyl acrylate, ethyl acrylate, butyl acrylate, and ethylhexyl acrylate. And acrylate monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethyl hexyl methacrylate and the like, and carboxylic acid monomers such as acrylic acid and fumaric acid. These polymerizable monomers may be used singly or in combination.

  It is also possible to use a mixture of crosslinkable monomers, and examples thereof include divinylbenzene, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

(Polymerization initiator)
Examples of the polymerization initiator used in the present invention include persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) 2 Hydrochloride, 2,2'-azobis-2-methyl-N-1,1'-bis (hydroxymethyl) -2-hydroxyethylpropioamide, 2,2'-azobis (2,4-dimethylvaleronitrile) Azo compounds such as 2,2'-azobisisobutyronitrile, 1,1'-azobis (1-cyclohexanecarbonitrile); di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroylper Oxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl perbutyl neodecanoate, t-hexyl -Oxy-2-ethylhexanoate, t-butyl peroxypivalate, t-hexyl peroxypivalate, di-isopropyl peroxydicarbonate, di-t-butyl peroxyisophthalate, 1,1 ', 3,3 Examples thereof include peroxides such as' -tetramethylbutylperoxy-2-ethylhexanoate and t-butylperoxyisobutyrate.

(Polymer dispersant)
Examples of the polymer dispersant used in the present invention include polyvinyl alcohol, polyacrylate, polymethacrylate, polyvinylpyrrolidone, polyacrylamide and the like, and preferably have a polymerization degree of 300 to 3000 and a saponification degree of 80. -95 partially saponified polyvinyl alcohol, sodium polyacrylate having a polymerization degree of 1000-10000, and the like.

(Surfactant)
A variety of surfactants can be used in the present invention.

  As an anionic surfactant, those containing an acidic group such as carboxylic acid, sulfonic acid, phosphoric acid, sulfate ester group, phosphate ester group, as a nonionic surfactant, alkylene oxide, glycerin, glycidol, etc. Examples of the cationic surfactant include alkylamines and quaternary ammonium salts.

(Polymerization inhibitor)
Examples of the polymerization inhibitor used in the present invention include ferric chloride, vanadium pentoxide, cupric chloride, sodium oxalate, ammonium molybdate, hydroquinone, sodium nitrite and the like.

(Aqueous medium)
In the present invention, the aqueous medium refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran and the like, and an alcohol-based organic solvent that does not dissolve the resulting composite resin particles is preferable.

(Manufacture of composite resin particles)
A polymer dispersion, a surfactant, and if necessary, a polymerization inhibitor are dissolved or dispersed in an aqueous medium such as water to prepare an aqueous dispersion. Moreover, a polymerization initiator is dissolved in the polymerizable monomer to prepare an oil-based dispersion. These aqueous dispersion and oil dispersion are stirred and mixed using a homomixer or the like to form an emulsion.

  At this time, when a polymerization inhibitor is not used, the value of a represented by Formula 1 is 0.2, when the polymerization inhibitor is used, the value of a represented by Formula 2 is 0.2 to 10, and When the ratio of the polymeric dispersant to the polymerizable monomer is 0.002 to 0.1 mol%, oil droplets smaller than the base are stable during polymerization, and the base oil droplets are being polymerized. Try to meet very narrow conditions that are slightly unstable.

  Next, the aqueous oil-based mixed solution (emulsion) is charged into a reaction vessel equipped with a stirrer, a heating / cooling device, and a concentrator, and polymerization is carried out by raising the internal temperature while stirring under a nitrogen stream. After the polymerization, the base particles and small-diameter particles smaller than the base are formed. The small-diameter particles are separated and removed by a centrifuge, and the remaining particles are separated from the aqueous medium, washed, dried, and composite resin particles. Get.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
4.5 g of polyvinyl alcohol (polymerization degree 500, saponification degree 88%) as a polymeric dispersant, 0.02 g of sodium alkyldiphenyl ether disulfonate as a surfactant, and 1.4 g of ferric chloride as a polymerization inhibitor And an aqueous dispersion was prepared.

  An oil-based dispersion was prepared by dissolving 1.6 g of azobisisobutyronitrile (AIBN) as a polymerization initiator and 50 g of styrene as a polymerizable monomer.

  Next, using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the oil dispersion is added while stirring the aqueous dispersion at 7000 rpm, so that the average particle size of the droplets becomes 6 μm. Suspended in water. Into a reaction flask equipped with a stirrer, a heating / cooling device, and a concentrating device, the aqueous oil-based mixed solution was charged, and the internal temperature was raised to 70 ° C. while stirring at 100 revolutions per minute under a nitrogen stream for 6 hours. Polymerization was performed. After the polymerization, 6 μm particles and 110 nm small-diameter particles were formed. The small-diameter particles were separated and removed by a centrifuge, and the 6 μm particles were filtered, washed and dried. The particle size was measured with Master Sizer 2000 (Malvern Instruments Ltd.). When this was observed with an electron microscope, it was a composite resin particle in which the entire particle surface was uniformly coated with small-diameter particles of 110 nm. FIG. 1A shows a copy of the electron micrograph of the composite resin particle. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In addition, the ultrasonic wave was applied for 5 minutes using ULTRASONIC CLEANER VS-150 (150W) of Vervo Creek Corporation. In this case, the value of a in Formula 2 was 0.89, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.015.

Example 2
In Example 1, 45 g of styrene as a polymerizable monomer, 0.023 g of sodium alkyldiphenyl ether disulfonate as a surfactant, 0 g of ferric chloride as a polymerization inhibitor, and azobisisobutyronitrile as a polymerization initiator were used. Composite resin particles were produced in the same manner except that the amount was changed to 0.54 g. When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 1 was 0.87, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.016.

Example 3
Composite resin particles were prepared in the same manner as in Example 1 except that the polymerization initiator azobisisobutyronitrile was changed to 6.4 g. When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 2 was 2.32, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.015.

Example 4
In Example 1, 9.0 g of polyvinyl alcohol (polymerization degree 500, saponification degree 88%) as a polymer dispersant, 100 g of styrene as a polymerizable monomer, and 3 azobisisobutyronitrile as a polymerization initiator were used. Composite resin particles were produced in the same manner except that the amount was changed to 2 g. When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 2 was 0.89, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.015.

Example 5
Composite resin particles were prepared in the same manner as in Example 1 except that the polymerization initiator was changed to 1.8 g of benzoyl peroxide (BPO). When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 2 was 0.71, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.015.

Example 6
Composite resin particles were prepared in the same manner as in Example 1 except that the polymer dispersant polyvinyl alcohol (polymerization degree 1800, saponification degree 88%) was changed to 4.5 g. When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 2 was 0.89, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.015.

Example 7
Composite resin particles were prepared in the same manner as in Example 1 except that the polymer dispersant was changed to 13.5 g of sodium polyacrylate (polymerization degree 5100). When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 2 was 0.89, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.006.

Example 8
Composite resin particles were prepared in the same manner as in Example 1 except that the polymerizable monomer was changed to 40 g of styrene and 10 g of methacrylic acid. When this was observed with an electron microscope, the entire particle surface was composite resin particles uniformly coated with small-diameter particles of 120 nm. It was confirmed that the composite resin particles did not peel off the small diameter particles even when ultrasonic waves were applied. In this case, the value of a in Formula 2 was 0.88, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.004.

Comparative Example 1
Composite resin particles were prepared in the same manner as in Example 1 except that the polymerization initiator azobisisobutyronitrile was changed to 0.4 g. When this was observed with an electron microscope, small-diameter particles adhered to the base particle surface, but were not entirely covered. FIG. 1B shows a copy of the electron micrograph of the composite resin particle. In this case, the value of a in Formula 2 was 0.18, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.015.

Comparative Example 2
Composite resin particles were produced in the same manner except that polyvinyl alcohol, which is a polymer dispersant, was changed to 0.36 g in Example 2. However, a large amount of small-diameter particles were generated during polymerization, and the particle size distribution of the matrix was also increased. It became wide. In this case, the value of a in Formula 1 was 0.87, and the mol% of the polymeric dispersant with respect to the polymerizable monomer was 0.001.

Comparative Example 3
Composite resin particles were prepared in the same manner as in Comparative Example 1 except that the tricalcium phosphate was changed to 9.0 g instead of the polymer dispersant. The tricalcium phosphate was dissolved in hydrochloric acid, washed and dried, and then observed with an electron microscope. No adhesion of small-diameter particles was observed on the base particle surface.

It is the figure which copied the electron micrograph of the composite particle.

Explanation of symbols

1 Matrix resin particles 2 Small-diameter particles adhering to the matrix

Claims (3)

In the method for producing composite resin particles in which resin particles (B) smaller than the matrix are adhered or fixed to the surface of the resin particles (A) serving as a matrix, the polymer dispersant and the surfactant are dissolved or dissolved in an aqueous medium. A step of dispersing to form an aqueous dispersion, a step of dissolving an initiator in a polymerizable monomer to form an oil-based dispersion, a step of mixing the aqueous dispersion and the oil-based dispersion to form an emulsion, The emulsion is heated and polymerized to attach or fix resin particles (B) smaller than the base to the surface of the base resin particles (A), and the value of a represented by the following formula 1 is 0. The method for producing composite resin particles, wherein the ratio is 2 to 10 and the ratio of the polymeric dispersant to the polymerizable monomer is 0.002 to 0.1 mol%.
Formula 1 a = b ^1/2
However, b represents the mol% of the polymerization initiator with respect to the polymerizable monomer. In the method for producing composite resin particles in which resin particles (B) smaller than the matrix are adhered or fixed to the surfaces of the resin particles (A) serving as a matrix, a polymer dispersant, a surfactant and a polymerization inhibitor are aqueous A step of forming an aqueous dispersion by dissolving or dispersing in a medium, a step of forming an oil dispersion by dissolving a polymerization initiator in a polymerizable monomer, and mixing the aqueous dispersion and the oil dispersion to form an emulsion. A step of forming, heating and polymerizing the emulsion, and attaching or fixing resin particles (B) smaller than the base to the surface of the base resin particles (A). Of the composite resin particles, wherein the value of the polymer dispersant is 0.002 to 0.1 mol% with respect to the polymerizable monomer Method.
Formula 2 a = b ^1/2 − (c × d) ^1/2
However, b is mol% of the polymerization initiator with respect to the polymerizable monomer.
c is the volume ratio of the polymerizable monomer to the aqueous medium
d is mol% with respect to the polymerizable monomer of the polymerization inhibitor.
Represents. It has the process of isolate | separating from the aqueous medium the composite resin particle which adhered or fixed the resin particle (B) smaller than this base material to the surface of the resin particle (A) used as the said base | matrix, and the process of drying. The manufacturing method of the composite resin particle of Claim 1 or 2.

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