KR20150089478A - Cross-linked acrylic particles, method for the production thereof, resin composition and packaging articles - Google Patents

Abstract

The present invention provides cross-linked acrylic resin particles contained and used in a pigment and capable of forming a film having excellent appearance and crack resistance. The acrylic resin particles of the present invention include acrylic resin, and heating loss after heating for 1.5 hours at 120°C is 1.5% or less. Moreover, a content of large diameter particles having a particle diameter, which is twice larger than a volume average particle diameter, is 1.0 volume% or less. Accordingly, when the particles are contained in a resin composition to be used in forming a film, the obtained film has excellent appearance and crack resistance.

Description

TECHNICAL FIELD [0001] The present invention relates to a crosslinked acrylic resin particle, a method for producing the same, a resin composition, and a packaging article. [0002] CROSS-LINKED ACRYLIC PARTICLES, METHOD FOR THE PRODUCTION THEREOF, RESIN COMPOSITION AND PACKAGING ARTICLES [

The present invention relates to crosslinked acrylic resin particles, a process for producing the same, a resin composition and a packaged article.

Resin particles prepared by the suspension polymerization method or the seed polymerization method are used in a wide variety of fields in place of inorganic particles as a gloss removing agent for paints, a lubricant for cosmetics, an additive for improving the physical properties of resin, a light diffusing agent and the like.

In general, when the resin particles obtained by the suspension polymerization method or the seed polymerization method are contained in a coating material or the like, the resin particles form irregularities on the surface of the coating film, thereby giving an effect of removing gloss to the surface of the coating film or imparting light diffusion to the coating film .

Particularly, crosslinked acrylic acid resin particles are widely used because of their excellent weatherability and transparency. In this case, when the particles are extremely excessively larger than the average diameter, that is, when coarse particles are present, they cause protrusions on the coating surface and cause deterioration of the outer appearance, and are easily removed from the coating surface. Performance may be degraded.

In addition, since volatile components in the particles, that is, moisture or remaining monomers, are present in a large amount, the intimate contact with the resin for coating or the solvent is poor and coagulation occurs or volatilizes during drying in the coating process. As a result, There is a problem in that the scratch-resistance performance of the film is deteriorated.

In Patent Document 1, a wet cake obtained by dewatering a suspension containing synthetic resin particles dispersed in an aqueous dispersion medium is washed, and then the wet cake is dried at a drying temperature of 60 to 90 ° C while stirring, The drying temperature is set to 100 to 140 캜 and the temperature of the synthetic resin particles is lower than the drying temperature by 3 캜 or more under a reduced pressure of 1 to 7 kPa So as to prepare a synthetic resin particle.

Patent Document 2 discloses a coating liquid containing an ultraviolet curing resin, a solvent, and light-transmitting fine particles having a weight average particle diameter of 1 占 퐉 or more, wherein the light-transmitting fine particles have a water content of 0.1 to 0.8% by mass.

Japanese Patent Application Laid-Open No. 2006-077047 Japanese Laid-Open Patent Publication No. 2012-215867

However, in the step of reducing coarse particles, the synthetic resin particles absorb moisture in the atmosphere to increase the volatile content, and the resin composition containing the resin particles and the coating liquid When a coating film is formed on a substrate to form a coating film, there is a problem that resin particles aggregate in the coating film or unevenness occurs due to volatile matter in the drying process and the scratch resistance of the coating film is deteriorated.

The present invention provides a crosslinked acrylic resin particle which can be used by being contained in a coating material and which is excellent in appearance and scratch resistance, and a process for producing the same, a resin composition using the crosslinked acrylic resin particle and a packaged article.

The crosslinked acrylic resin particle of the present invention contains an acrylic resin and has a weight loss after heating at 120 DEG C for 1.5 hours of 1.5% or less and a content of large diameter particles having a particle diameter of 2 times or more of the volume average particle diameter is 1.0 volume% or less .

The acrylic resin contained in the crosslinked acrylic resin particles of the present invention is preferably obtained by polymerizing raw monomer containing an acrylic monomer and polymerizing raw monomer containing an acrylic monomer and a polyfunctional monomer. It is preferable that the acrylic resin contained in the crosslinked acrylic resin particle is crosslinked by the polyfunctional monomer. The acrylic monomer is not particularly limited, and examples thereof include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, dodecyl acrylate, stearyl acrylate, Methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, isopropyl methacrylate, Acrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate and the like. Of these, methyl methacrylate is preferable in that crosslinked acrylic resin particles with small variation in particle strength within the particle size distribution can be obtained. The acrylic monomers may be used alone or in combination of two or more.

Examples of the polyfunctional monomer include trimethylol propane tri (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) Acrylates such as ethylene glycol di (meth) acrylate, pentadecaethylene glycol di (meth) acrylate, pentaconthectaethylene glycol di (meth) acrylate, pentaerythritol tetra Acrylate and allyl (meth) acrylate, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof, and the like. Of these, acrylic multi-functional monomers are preferable from the viewpoint of obtaining crosslinked acrylic resin particles with small variation in particle strength within the particle size distribution, and acrylic multi-functional monomers having a plurality of (meth) acryloyl groups are more preferable . In addition, the polyfunctional monomer may be used alone or in combination of two or more. In the present invention, (meth) acrylate means acrylate or methacrylate. In the present invention, the (meth) acryloyl group means an acryloyl group or a methacryloyl group.

The acrylic multi-functional monomer is not particularly limited, and examples thereof include acrylic multi-functional monomers produced by the dehydration esterification method (A) and acrylic multi-functional monomers produced by the ester exchange method (B) Among them, the acrylic multifunctional monomer produced by the dehydration esterification method (A) is preferable.

The dehydrating esterification method (A) is a method in which raw alcohol, (meth) acrylic acid and acidic catalyst are fed into a solvent to esterify raw alcohol and (meth) acrylic acid, neutralization and washing to remove water and solvent out of the system to obtain acrylic multi- Refers to a method for producing a monomer. Further, (meth) acrylic acid means acrylic acid or methacrylic acid.

Examples of the raw alcohol include trimethylol propane, ethylene glycol, diethylene glycol, triethylene glycol, decaethylene glycol, pentadecaethylene glycol, pentaconthectaethylene glycol, pentaerythritol, 1,3-butanediol and allyl alcohol have. Of these, ethylene glycol is preferable.

Examples of the acidic catalyst include sulfonic acid-based catalysts such as concentrated sulfuric acid and para-toluenesulfonic acid. Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene and xylene.

The ester exchange method (B) refers to a method of producing an acrylic multi-functional monomer by reacting a raw alcohol with a lower (meth) acrylic acid ester using a neutral catalyst. Alcohol produced is removed out of the system. Further, since the same alcohols as the dehydrating esterification method (A) can be used as the starting alcohol, the description thereof will be omitted. The neutral catalyst is not particularly limited and includes, for example, lithium hydroxide, lithium hydroxide monohydrate, lithium methoxide, lithium hydride, lithium acetate and lithium amide.

In the ester exchange method (B), since the ester exchange reaction between the starting alcohol and the lower (meth) acrylic acid ester is an equilibrium reaction, about 1 to 3% by weight remains in the acrylic polyfunctional monomer from which unreacted raw alcohol can be obtained under ordinary synthesis conditions . In addition, since the boiling point of the unreacted starting alcohol and the obtained boiling point of the acrylic multi-functional monomer are close to each other, it may be difficult to remove only the unreacted starting alcohol out of the system.

Therefore, the acrylic multi-functional monomer is preferably an acrylic multi-functional monomer produced by the dehydration esterification method (A) containing a small amount of volatile substances such as a starting alcohol. Further, the (meth) acrylic acid and And an acrylic multi-functional monomer purified by removal of a catalyst or the like is more preferable. As described above, the crosslinked acrylic resin particles obtained by polymerizing raw monomers containing an acrylic polyfunctional monomer having a small content of volatile substances and impurities have a low content of volatile substances and impurities. For example, when a resin composition containing a crosslinked acrylic resin particle and a binder resin is coated on a coated surface to form a coated film and the coated film is dried to form a coated film, the volatiles contained in the crosslinked acrylic resin particles Bubbles originating from substances and impurities rarely occur in the coating film, and because of good affinity with a solvent, a coating film excellent in adhesion with the coating surface, appearance and scratch resistance can be obtained.

The content of the polyfunctional monomer in the raw material monomer is preferably 1 to 100 parts by weight, more preferably 5 to 80 parts by weight, based on 100 parts by weight of the acrylic monomer, from the viewpoint of obtaining crosslinked acrylic resin particles with small variation in particle strength within the particle size distribution More preferably from 20 to 50 parts by weight.

The raw material monomer may contain a monomer copolymerizable with the acrylic monomer. Examples of such a monomer include, but are not limited to, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,? -Methylstyrene, vinyl chloride, vinyl acetate, acrylonitrile, acrylamide, methacryl Amide, N-vinylpyrrolidone, and the like. These monomers may be used alone, or two or more of them may be used in combination.

The crosslinked acrylic resin particles of the present invention can be formed into a resin composition by mixing with a binder resin, and the resin composition is coated on an optional coating surface such as a substrate and dried to form a coating film.

As a result of intensive studies on the scratch resistance of the coating film obtained by the present inventors, the present inventors have found that when the amount of volatile matter such as residual monomers and water contained in the crosslinked acrylic resin particles is large, the binder resin in the resin composition, And the dispersibility of the crosslinked acrylic resin particles in the binder resin is lowered.

Further, the inventors of the present invention have found that, in a drying step of coating a resin composition on a coated surface and then drying the coated film, volatile components such as residual monomers and water contained in the crosslinked acrylic resin particles are released from the crosslinked acrylic resin particles, Bubbles are generated in the coating film due to residual volatile components such as residual monomers and water. In the portion where the bubbles are present, the amount of the binder resin decreases and the adhesion of the binder resin and the crosslinked acrylic resin particles decreases. It is found that the scratch resistance is lowered and the coagulation of the crosslinked acrylic resin particles is promoted by the presence of bubbles.

In other words, the crosslinked acrylic resin particles of the present invention have a weight loss of not more than 1.5%, preferably not more than 1.0%, after heating at 120 ° C for 1.5 hours (hereinafter sometimes simply referred to as "heat loss" The total amount of volatile matter such as residual monomers and moisture contained in the acrylic resin particles can be reduced. By decreasing the total amount of volatile matter such as residual monomer and moisture, it is possible to improve the intimacy with the binder resin and the solvent to improve the dispersibility of the crosslinked acrylic resin particles in the binder resin and to improve the dispersibility of the crosslinked acrylic resin particles into the coating film It is possible to prevent the generation of bubbles in the coating film by suppressing the amount of volatile components such as residual monomers and moisture released and improve the adhesion between the binder resin and the crosslinked acrylic resin particles and to prevent coagulation of the crosslinked acrylic resin particles Therefore, according to the acrylic resin particles of the present invention, a coating film having excellent scratch resistance can be formed.

The heating and the weight loss of the acrylic resin particles refers to the values measured in the following manner. ₉ to 10 g of the acrylic resin particles are weighed into a beaker (W ₃ ) of 100 cm 3 having a constant mass, and the weight (W ₁ ) of the sample and the beaker is read to 0.1 mg unit. The beaker containing the sampled sample is allowed to stand at 120 ° C. for 1.5 hours, and then the beaker is taken out and the weight (W ₂ ) after standing for 30 minutes in a desiccator containing silica gel is measured. The measurement is carried out in an environment at a temperature of 23 ° C to 27 ° C in a laboratory room, and the heating loss of the acrylic resin particles is calculated based on the following formula.

Heat loss (%) = 100 x (W ₁ -W ₂ ) / (W ₁ -W ₃ )

W ₁ : total weight of sample before beating and beaker (g)

W ₂ : total weight of sample and beaker after heating (g)

W ₃ : weight of beaker (g)

The crosslinked acrylic resin particles of the present invention have a content of particles having a particle diameter of not less than twice the volume average particle diameter (hereinafter sometimes simply referred to as " large diameter particle ") of 1.0 volume% or less. As described above, the content of the particles (large-diameter particles) having a particle diameter of at least two times the volume average particle diameter of the crosslinked acrylic resin particles of the present invention is limited to 1.0% by volume or less, preferably 0.5% by volume or less.

As described above, by limiting the content of the large-diameter particles contained in the crosslinked acrylic resin particles to a predetermined amount or less, it is possible to substantially suppress the protrusion of large-diameter particles on the surface of the coating film formed of the resin composition containing the crosslinked acrylic resin particles, Can be made good. In addition, it is possible to prevent large-diameter particles from falling off from the surface of the coating film, thereby improving the scratch resistance of the coating film.

The volume average particle diameter of the crosslinked acrylic resin particles is preferably 50 占 퐉 or less because the appearance of the coating film formed of the resin composition containing the crosslinked acrylic resin particles and the scratch resistance of the coating film are improved and the aggregation of the crosslinked acrylic resin particles is further prevented More preferably 3 to 30 占 퐉, and particularly preferably 5 to 20 占 퐉, because the appearance and scratch resistance of the coating film can be further improved.

The volume average particle diameter of the acrylic resin particles is measured by Coulter Multisizer III (measuring apparatus manufactured by Beckman Coulter, Inc.). The measurement shall be carried out using the calibrated aperture in accordance with the user's manual of Multisizer ^TM 3 issued by Beckman-Coulter.

The aperture used for the measurement is selected by selecting an aperture having a size of 50 mu m when the assumed volume average particle diameter of the resin particle to be measured is 1 mu m or more and 10 mu m or less, An aperture having a size of 100 mu m is selected when the particle diameter is larger than 10 mu m and 30 mu m or smaller and an aperture having a size of 280 mu m is selected when the assumed volume average particle diameter of the resin particle is larger than 30 mu m and 90 mu m or smaller And so on. When the volume average particle diameter after measurement is different from the assumed volume average particle diameter, the aperture is changed to an aperture having an appropriate size, and measurement is performed again.

When an aperture having a size of 50 mu m is selected, the current (aperture current) is set to -800 and the gain (gain) is set to 4. When an aperture having a size of 100 mu m is selected, The current is set to -1600 and the gain is set to 2. When the aperture having the sizes of 280 μm and 400 μm is selected, the current (aperture current) is set to -3200 and the gain (gain) is set to 1 .

0.1 g of the crosslinked acrylic resin particles was dissolved in 10 ml of a 0.1% by weight nonionic surfactant aqueous solution by using a touch mixer (TOUCHMIXER MT-31 manufactured by Yamato Scientific Co., Ltd.) and an ultrasonic cleaner (ULTRASONIC CLEANER VS -150 ") as a dispersion liquid. A beaker filled with ISOTON (registered trademark) II (manufactured by Beckman Coulter, measurement electrolyte) was placed in the measuring section of the Coulter Multisizer III, and the dispersion was dropped while slowly stirring the beaker, Ⅲ Start measurement after adjusting the concentration meter to 5 to 10% on the main body screen. During the measurement, the inside of the beaker was slowly stirred so as not to contain bubbles, and the measurement was terminated at the time when 100,000 particles were measured. The volume average particle diameter of the crosslinked acrylic resin particles is an arithmetic average in the particle size distribution based on the volume of 100,000 particles.

It is preferable that porous crosslinked acrylic resin particles are used in order to improve high gloss removability or adhesion to a binder resin. Since the porous crosslinked acrylic resin particles have a large specific surface area, they are highly hygroscopic and have a high volatilization amount, so that a good coating film may not be obtained. Therefore, it is desirable to suppress the heating loss to a low level.

Next, a method for producing the crosslinked acrylic resin particles of the present invention will be described. The method for producing the crosslinked acrylic resin particles of the present invention is not particularly limited, but it is preferable that the crosslinking acrylic resin particles are polymerized by a polymerization method, followed by a drying step for drying the crosslinked acrylic resin particles and a classification step for classifying crosslinked acrylic resin particles . ≪ / RTI > The polymerization method is not particularly limited as long as it is a known polymerization method. Known polymerization methods include, for example, bulk polymerization, emulsion polymerization, soap-free emulsion polymerization, seed polymerization, suspension polymerization and the like. Suspension polymerization and seed polymerization are preferable in that particles having a particle size of 1 占 퐉 or more are obtained.

First, the case of employing suspension polymerization as the polymerization method will be described. The polymerization process will be described. In the polymerization step, a raw material monomer containing an acrylic monomer and a polyfunctional monomer is subjected to suspension polymerization in an aqueous medium in the presence of a polymerization initiator to obtain a suspension containing crosslinked acrylic resin particles. Suspension polymerization is carried out by dispersing a droplet of a mixture (oil phase) containing a raw material monomer and a polymerization initiator in an aqueous medium (water phase) to polymerize the raw monomer.

The aqueous medium is not particularly limited and includes, for example, a mixed medium of water, water and a water-soluble organic medium (a lower alcohol such as methanol or ethanol (alcohol having 5 or less carbon atoms)). The amount of the aqueous medium to be used is preferably 100 to 1000 parts by weight per 100 parts by weight of the raw material monomer in order to stabilize the crosslinked acrylic resin particles.

A dispersion stabilizer may be contained in the aqueous medium. Examples of the dispersion stabilizer include phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate, pyrophosphates such as calcium pyrophosphate, magnesium pyrophosphate, aluminum pyrophosphate and zinc pyrophosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide , Water-soluble inorganic compounds such as aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate and colloidal silica, and water-soluble polymers such as polyvinyl pyrrolidone and polyvinyl alcohol. Among them, when a substance decomposed by an acid and dissolved in water (for example, calcium carbonate, tribasic calcium phosphate, magnesium hydroxide, magnesium pyrophosphate, calcium pyrophosphate) is used, the dispersion stabilizer is easily removed It is preferable. The dispersion stabilizer may be used alone or in combination of two or more.

The amount of the dispersion stabilizer to be used is preferably from 0.1 to 20 parts by weight, more preferably from 0.5 to 10 parts by weight, based on 100 parts by weight of the raw material monomer, from the standpoint of good dispersibility of the crosslinked acrylic resin particles in the suspension while securing the fluidity of the suspension desirable.

The polymerization initiator is not particularly limited as long as it is capable of initiating polymerization of the raw material monomer. However, the polymerization initiator is not particularly limited as long as the polymerization initiator has a 10-hour half-life temperature of 40 to 80 캜. Examples thereof include benzoyl peroxide, lauroyl peroxide, Organic peroxides such as ethylhexanoate, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis Dimethylvaleronitrile) and the like are preferably used. The polymerization initiator may be used alone, or two or more thereof may be used in combination.

The amount of the polymerization initiator to be used is preferably 0.01 to 10 parts by weight, more preferably 0.01 to 7 parts by weight, and particularly preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the raw material monomer, since the suspension polymerization of the raw material monomer can be smoothly initiated .

In order to further stabilize the suspension (reaction liquid) in the suspension polymerization, a surfactant may be contained in the aqueous medium. As the surfactant, any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and a positive ion surfactant can be used. The surfactant may be used alone, or two or more surfactants may be used in combination.

The anionic surfactant includes, for example, sodium oleate; Fatty acid oils such as castor oil and potassium; Alkyl sulfuric acid ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate; Alkylbenzene sulfonic acid salts such as sodium dodecylbenzenesulfonate; Alkyl naphthalene sulfonic acid salts; Alkanesulfonic acid salts; Dialkylsulfosuccinates such as sodium dioctylsulfosuccinate; Alkenylsuccinates (dipotassium salts); Alkyl phosphoric acid ester salts; Naphthalenesulfonic acid formalin condensate; Polyoxyethylene alkyl ether sulfate such as polyoxyethylene alkylphenyl ether sulfuric acid ester salt and polyoxyethylene lauryl ether sodium sulfate; And polyoxyethylene alkyl sulfate ester salts.

Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate; And quaternary ammonium salts such as lauryltrimethylammonium chloride.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxy sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid Ester, oxyethylene-oxypropylene block polymer, and the like.

Examples of the amphoteric surfactant include lauryldimethylamine oxide, phosphate ester surfactant, phosphorous ester surfactant, and the like.

In order to reduce the amount of monomer remaining in the resulting crosslinked acrylic resin particle, the polymerization temperature of the raw material monomer is divided into a first temperature range and a second temperature range higher than the first temperature range in the polymerization step, , It is preferable that the raw material monomer is further subjected to suspension polymerization in the second temperature range.

The first temperature range is preferably 30 占 폚 or higher, more preferably lower than 80 占 폚, and more preferably 40 to 70 占 폚. The second temperature range needs to be higher than the first temperature range, preferably 60 to 120 ° C, more preferably 80 to 120 ° C, and particularly preferably 90 to 105 ° C.

As described above, the suspension polymerization is carried out by dividing the suspension polymerization temperature of the raw material monomer into the first temperature region and the second temperature region, thereby gradually polymerizing the raw monomer while slowly decomposing the polymerization initiator in the first temperature region at a low temperature, The polymerization rate of the raw material monomer can be increased in the second temperature region higher than the first temperature region to promote the polymerization of the raw material monomer and the amount of the residual monomer contained in the resulting crosslinked acrylic resin particle Can be reduced.

The suspension polymerization time of the raw material monomer in the first temperature range is preferably 0.1 to 15 hours since the polymerization of the raw material monomer can be sufficiently proceeded. The suspension polymerization time of the raw material monomer in the second temperature range is preferably 0.5 to 5 hours since the amount of the residual monomer in the obtained crosslinked acrylic resin particles can be effectively reduced.

Next, the case where the seed polymerization is adopted as the polymerization method will be described. First, the seed particles are added to the emulsion (suspension) composed of the raw material monomer and the aqueous medium. The emulsion can be prepared by a known method. For example, an emulsion can be obtained by adding a raw material monomer to an aqueous medium and dispersing the emulsion through a micro emulsifier such as a homogenizer, an ultrasonic processor or a nanometer. Examples of the aqueous medium include water or a mixture of water and an organic solvent (for example, a lower alcohol).

The method for producing the seed particles to be produced separately is not particularly limited, and for example, emulsion polymerization, soap-free emulsion polymerization or suspension polymerization may be used. In consideration of grain size uniformity of the seed particles and simplicity of the production method, emulsion polymerization or soap-free emulsion polymerization method is preferable. The weight average molecular weight of the seed particles may be adjusted by the amount of the polymerization initiator used or the amount of the molecular weight adjuster added.

The raw material monomer may optionally contain a polymerization initiator. The polymerization initiator may be preliminarily mixed in the monomer and then dispersed in the aqueous medium, or both may be dispersed in the aqueous medium separately. The droplet size of the raw material monomer present in the obtained emulsion is preferably smaller than that of the seed particle because the monomer is efficiently absorbed into the seed particle.

The seed particles may be directly added to the emulsion or may be added in the form of dispersing the seed particles in an aqueous medium (hereinafter referred to as seed particle dispersion). After the seed particles are added to the emulsion, the raw monomer is absorbed into the seed particles. This absorption can be usually performed by stirring the emulsion after seed particle addition at room temperature (20 ° C) for 1 to 12 hours. Further, the emulsion may be heated to about 30 to 50 DEG C to promote the absorption of the monomer.

The seed particles swell by absorbing the monomer. The mixing ratio of the monomer and the seed particle is preferably 5 to 300 parts by weight, more preferably 100 to 250 parts by weight, of the starting monomer to 1 part by weight of the seed particles. When the mixing ratio of the raw material monomer is small, the particle size increase due to polymerization becomes small, and when the mixing ratio of the raw material monomer is large, the raw material monomer is not completely absorbed by the seed particles but suspended and polymerized independently in an aqueous medium, May be generated. The completion of the absorption of raw material monomer by the seed particles can be judged by confirming the enlargement of the particle size by observing with an optical microscope.

The polymerization initiator to be added as needed is not particularly limited and includes, for example, benzoyl peroxide, lauroyl peroxide, orthochloro benzoyl peroxide, orthomethoxy benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t Organic peroxides such as butyl peroxy-2-ethylhexanoate and di-t-butyl peroxide; (2,4-dimethylvaleronitrile), 2,2'-azobis (2,3-dimethylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'- Azobis (2-methylbutyronitrile), 2,2'-azobis (2,3,3-trimethylbutyronitrile), 2,2'-azobis (2-isopropylbutyronitrile) Azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile, (2-carbamoyl azo) isobutyl Azo compounds such as acrylonitrile, 4,4'-azobis (4-cyanovaleric acid) and dimethyl-2,2'-azobisisobutyrate, etc. The polymerization initiator may be added in an amount of It is preferably used in a range of 0.1 to 1.0 part by weight.

Next, acrylic resin particles are obtained by polymerizing raw material monomers absorbed in the seed particles. The polymerization temperature may be appropriately selected depending on the kind of the raw material monomer or the polymerization initiator. In order to reduce the amount of the monomer remaining in the obtained crosslinked acrylic resin particles, the polymerization temperature of the raw material monomer It is preferable that the raw material monomer is further polymerized in the second temperature region after the raw material monomer is polymerized in the first temperature region and then divided into the first temperature region and the second temperature region which is higher than the first temperature region. Concretely, the first temperature range is preferably 30 占 폚 or higher, more preferably lower than 80 占 폚, and more preferably 40 to 70 占 폚. The second temperature range needs to be higher than the first temperature range, preferably 60 to 120 ° C, more preferably 80 to 120 ° C, and particularly preferably 90 to 105 ° C. The polymerization may be carried out under an inert gas atmosphere inert to polymerization such as a nitrogen atmosphere. In addition, it is preferable that the polymerization reaction is performed by raising the temperature of the seed particles after the raw monomers and optionally used polymerization initiators are completely absorbed.

In the polymerization step, a polymer dispersion stabilizer may be added to improve the dispersion stability of the resin particles. Examples of the polymer dispersion stabilizer include polyvinyl alcohol, polycarboxylic acid, cellulose (hydroxyethylcellulose, carboxymethylcellulose, etc.), and polyvinylpyrrolidone. In addition, an inorganic water-soluble polymeric compound such as sodium tripolyphosphate may be used in combination. Of these polymer dispersion stabilizers, polyvinyl alcohol and polyvinyl pyrrolidone are preferable. The addition amount of the polymer dispersion stabilizer is preferably 1 to 10 parts by weight per 100 parts by weight of the raw material monomer.

Water-soluble polymerization inhibitors such as nitrites, sulfites, hydroquinones, ascorbic acids, water-soluble vitamin B, citric acid and polyphenols may be used in order to suppress the generation of emulsified particles in the aqueous system in the above-mentioned polymerization step.

The crosslinked acrylic resin particles are separated from the suspension obtained in the polymerization step described above by filtration and washed with water or the like to obtain crosslinked acrylic resin particles.

Next, the crosslinked acrylic resin particles obtained as described above are preferably subjected to a drying step. By carrying out the drying step on the crosslinked acrylic resin particles, it is possible to further reduce the amount of residual monomer and water contained in the crosslinked acrylic resin particles, and to reduce the heating loss of the obtained crosslinked acrylic resin particles.

The drying temperature of the crosslinked acrylic resin particles is preferably from 30 to 90 占 폚, more preferably from 60 to 80 占 폚, since the residual monomers and water content contained in the crosslinked acrylic resin particles can be effectively reduced.

The drying of the crosslinked acrylic resin particles is preferably carried out under a reduced pressure since the residual monomer contained in the crosslinked acrylic resin particles and the amount of water can be effectively reduced. The degree of vacuum of the crosslinked acrylic resin particles during drying is preferably 0.03 to 0.09 MPa, more preferably 0.05 to 0.08 MPa. The " vacuum degree " refers to an absolute value of the pressure difference with atmospheric pressure, which is a pressure of atmospheric pressure or less.

The drying time of the crosslinked acrylic resin particles is preferably from 3 to 24 hours, more preferably from 5 to 20 hours, since the residual monomer contained in the crosslinked acrylic resin particles and the moisture content can be effectively reduced.

Next, particles having a large particle diameter are removed by classification so that the content of the particles (large-diameter particles) having a particle size of 2 times or more of the volume average particle size (large-diameter particle) in the obtained crosslinked acrylic resin particle is 1.0 volume% or less (classification process) .

The classification method of the crosslinked acrylic resin particles is not particularly limited as long as the particles having a large particle size can be removed by classification, and examples thereof include wind power classification and screen classification. Among these, the classification of the wind power is preferable because the crosslinked acrylic resin particles having a small average particle diameter can be classified without generating clogging. Wind classification refers to a method of classifying particles using air flow. Screen classification refers to a method of supplying crosslinked acrylic resin particles onto a screen and vibrating the screen to classify the crosslinked acrylic resin particles on the screen into particles that do not pass through the mesh of the screen.

(1) a method in which crosslinked acrylic resin particles are loaded on a stream of air to cause the crosslinked acrylic resin particles to collide with the screen and classified into particles that do not pass through the mesh of the screen and particles that do not pass through the screen; (2) A method of putting the resin particles in a flow of a swirling air current and classifying them into large and small particle diameters by interaction of the centrifugal force applied to the crosslinked acrylic resin particles by the swirling air current and the flow of the air current toward the swirl center of the air current . Examples of the apparatus for classifying wind power according to the above (1) include a classifier "Blower Shifter" available from Yugropsa, a classifier "Hi-Bolter" available from Toyo Hi-Tech Co., and a classifier commercially available from Makino Industries Co., . Examples of the apparatus for classifying wind power according to (2) include a turboclassifier commercially available from Nissei Engineering Co., Ltd., and a classification apparatus commercially available from Seishin Enterprise Co., Ltd. under the trade name "SPEDIC CLASSIFIER". The two classification methods can be classified and used depending on the properties of the acrylic resin particles to be classified or the desired level of coarse particle removal. When the adhesion of the acrylic resin particles is high and when it is desired to improve the removal accuracy of the coarse particles, it is preferable to use the airflow classifier of (2).

Since the scale interval of the screen used in the wind power classification (1) does not cause clogging and particles with a large particle size can be efficiently classified and removed, it is preferable that the volume average particle diameter of the cross- More preferably from 3 to 5 times.

It is preferable that the wind power classification is performed in an atmosphere of dehumidified air because it is possible to keep the heat loss of the crosslinked acrylic resin particles small. Specifically, it is preferable to perform the operation in an atmosphere having a relative humidity of air of 30% And more preferably in an atmosphere having a humidity of 20% or less.

It is preferable that the crosslinked acrylic resin particles thus obtained are sealed with a packaging material which is difficult to permeate moisture after production so as not to absorb moisture in the air and stored as a packaged article. As a packaging material which is difficult to permeate moisture, a packaging material having a water vapor permeability of 50 g / m 2 24 hours or less is preferable. As such a packaging material, for example, a bag made of low-density polyethylene having a thickness of 50 to 150 占 퐉, a bag made of a vapor-deposited film having a metal film deposited on one side of a synthetic resin film, And the like, and the like. The water vapor transmission rate of the packaging material is preferably 50 g / m 2 24 hours or less, and more preferably 30 g / m 2 24 hours or less. The water vapor permeability was measured using a water vapor permeability measuring apparatus ("Fermatan (registered trademark) W3 / 31" manufactured by MOCON CORPORATION, USA) under conditions of a temperature of 40 ° C. and a relative humidity of 90% (Infrared sensor method). Further, the measurement is performed once for each of the two test pieces, and the average value of the two measured values is taken as the value of the water vapor transmission rate.

Next, an example of usage of the crosslinked acrylic resin particles of the present invention will be described. The resin composition is prepared by mixing the crosslinked acrylic resin particles obtained as described above with the binder resin.

The resin composition may contain a solvent for adjusting the viscosity. The solvent is not particularly limited, and examples thereof include toluene, methyl ethyl ketone, ethyl acetate, alcohol and the like. The solvent may be used alone, or two or more solvents may be used in combination.

As a method of producing the resin composition, the crosslinked acrylic resin particles and the binder resin may be mixed by using a general-purpose mixer. Examples of the mixer include a kneader such as an extruder, a bead mill, and a high-pressure homogenizer.

As the binder resin, any of an ionizing radiation curable resin such as an ultraviolet ray curable resin and an electron beam curable resin, a thermoplastic resin, or a thermosetting resin may be used. The binder resin may be used alone, or two or more kinds thereof may be used in combination. Examples of the thermoplastic resin include polyolefin resins such as the acrylic resin, polycarbonate, polyester resin, polyethylene resin and polypropylene resin, and polystyrene resins. Of these, an acrylic resin, a polycarbonate, a polyester resin and a polystyrene resin are preferable from the viewpoint of excellent transparency. The thermoplastic resin may be used alone or in combination of two or more. In the present specification, the term " binder resin " is a concept including a monomer as a raw material of the binder resin and an oligomer obtained by polymerizing the monomer, unless otherwise specified.

Examples of the thermosetting resin include thermosetting urethane resins, phenol resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins, each of which is composed of an acrylic polyol and an isocyanate-free polymer.

Examples of the ionizing radiation curable resin include polyfunctional (meth) acrylate resins such as polyhydric alcohol polyfunctional (meth) acrylates and the like; Polyfunctional urethane acrylate resins synthesized with diisocyanates, polyhydric alcohols, (meth) acrylic esters having a hydroxy group, and the like. As the ionizing radiation curable resin, a polyfunctional (meth) acrylate resin is preferable, and a polyfunctional (meth) acrylate resin having three or more (meth) acryloyl groups in one molecule is more preferable. Specific examples of polyhydric alcohol polyfunctional (meth) acrylate resins having three or more (meth) acryloyl groups in one molecule include trimethylolpropane tri (meth) acrylate, trimethylol ethane tri (meth) acrylate (Meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol triacrylate, (Meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol triacrylate, tripentaerythritol hexaacrylate, and the like . The ionizing radiation curable resin may be used alone, or two or more kinds thereof may be used in combination.

As the ionizing radiation curable resin, a polyether resin having an acrylate functional group, a polyester resin having an acrylate functional group, an epoxy resin having an acrylate functional group, an alkyd having an acrylate functional group Resin, a spiroacetal resin having an acrylate functional group, a polybutadiene resin having an acrylate functional group, and a polythiol polyene resin having an acrylate functional group.

When an ultraviolet ray curable resin is used as the ionizing radiation curable resin, a photopolymerization initiator is added to the ultraviolet ray curable resin to form a binder resin. The photopolymerization initiator is not particularly limited. Examples of the photopolymerization initiator include a photopolymerization initiator such as acetophenone, benzoin, benzophenone, phosphine oxides, ketaldehyde,? -Hydroxyalkylphenones,? -Aminoalkylphenones, anthraquinones, , An azo compound, a peroxide compound (described in JP 2001-139663 A), a 2,3-dialkyldione compound, a disulfide compound, a fluoroamine compound, an aromatic sulfonium compound, an onium salt, a borate salt, Active halogen compounds, and? -Acyloxime esters.

Examples of the acetophenones include acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenylketone, 1-hydroxycyclohexylphenylketone, 2- 4-methylthio-2-morpholinopropiophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone and the like. Examples of the benzoin include benzoin, benzoin benzoate, benzoin benzenesulfonic acid ester, benzoin toluenesulfonic acid ester, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and the like. Examples of benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone, and p-chlorobenzophenone. Examples of the phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. Examples of the ketalization include benzylmethyl ketal such as 2,2-dimethoxy-1,2-diphenylethane-1-one and the like. Examples of the? -hydroxyalkylphenols include 1-hydroxycyclohexyl phenyl ketone and the like. Examples of the? -aminoalkylphenols include 2-methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propanone.

Commercially available photo radical polymerization initiators include trade names "Irgacure (registered trademark) 651" (2,2-dimethoxy-1,2-diphenylethane-1-one) manufactured by BASF Japan KK, Irgacure (registered trademark) 184 ", trade name" Irgacure (registered trademark) 907 "(trade name, manufactured by BASF Japan KK) (2-methyl-1- (4-methylthiophenyl) -On), and the like can be mentioned as preferable examples.

The amount of the photopolymerization initiator to be used is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, and particularly preferably 1 to 8 parts by weight, based on 100 parts by weight of the binder resin.

The content of the binder resin in the resin composition is preferably from 25 to 4000 parts by weight, more preferably from 50 to 2000 parts by weight, based on 100 parts by weight of the crosslinked acrylic resin particles, from the viewpoint of producing an optical material excellent in both light diffusibility and light- The addition is more preferable.

A coating film containing the crosslinked acrylic resin particles can be formed by coating the resin composition on an optional coating surface such as a substrate to prepare a coating film, drying the coating film, and then curing the coating film as necessary. As a method of coating the resin composition on the coated surface, known methods such as a reverse roll coating method, a gravure coating method, a die coating method, a comma coating method and a spray coating method can be used.

An optical film can be obtained by using a transparent film base as a base material and coating the resin composition. The optical film can be used as an antiglare film or the like. The material of the transparent film base material is not particularly limited as long as it has transparency, and examples thereof include polyester resins such as polyethylene terephthalate, triacetylcellulose resin, polystyrene resin, acrylic resin, polycarbonate resin, cycloolefin- . The thickness of the transparent film base material is preferably 5 to 300 mu m. When the thickness of the transparent film substrate is thinner than 5 占 퐉, handling of the transparent film substrate during coating, printing, and secondary processing becomes difficult and the workability may be deteriorated in some cases. On the other hand, when the thickness of the transparent film base material is larger than 300 탆, the visible light transmittance of the transparent film base material itself may be deteriorated.

The resin composition contains the crosslinked acrylic resin particles, but the crosslinked acrylic resin particles have a heating loss of 1.5% or less, and the remaining monomers contained in the crosslinked acrylic resin particles and the water content are small, And the crosslinked acrylic resin particles do not aggregate during the coating of the resin composition, and the crosslinked acrylic resin particles are well dispersed in the thermoplastic resin. Therefore, even in the obtained coated film, the crosslinked acrylic resin particles are not agglomerated and exist in a state of being well dispersed in the binder resin.

In addition, the total amount of residual monomers and moisture released from the crosslinked acrylic resin particles during drying of the coating film is very small, because residual monomers contained in the crosslinked acrylic resin particles and the amount of water are small. Therefore, the resulting coating film contains almost no residual monomer released from the crosslinked acrylic resin particles and bubbles due to moisture, and the obtained coating film has excellent scratch resistance.

In addition, since the content of the large diameter particles contained in the crosslinked acrylic resin particles is not more than 1.0% by volume, the large diameter particles do not almost protrude from the surface of the obtained coating film, Since the particles are rarely dropped off, the resulting coating film has an excellent appearance.

The acrylic resin particle of the present invention has the above-described structure, and when used for forming a coating film contained in the resin composition, the resulting coating film has excellent appearance and scratch resistance.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

(Example 1)

5 parts by weight of tribasic calcium phosphate as an inorganic dispersion stabilizer and 0.005 part by weight of sodium lauryl sulfate as an anionic surfactant were added to 100 parts by weight of deionized water to form an aqueous phase.

On the other hand, 0.2 part by weight of benzoyl peroxide and 0.2 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator were dissolved in a raw material monomer containing 35 parts by weight of methyl methacrylate and 15 parts by weight of ethylene glycol dimethacrylate And was paid. Ethylene glycol dimethacrylate was prepared by dehydration esterification and further purified by distillation. The purity of the ethylene glycol dimethacrylate was 98.1% by weight.

The aqueous phase and the aqueous phase were stirred and mixed at a rotation number of 2500 rpm using a dispersing machine (trade name: T.K. Homomixer MODEL S, manufactured by FRIMICS Co., Ltd.), and an oil phase droplet was dispersed in the aqueous phase to obtain a dispersion. After the dispersion was supplied to a polymerization reactor equipped with a stirrer and a thermometer, the dispersion was heated to 55 deg. C (first temperature region) while stirring the dispersion, and the raw monomer was subjected to suspension polymerization for 3 hours. Subsequently, the dispersion was heated to 100 캜 (second temperature region), and the raw monomer was subjected to suspension polymerization for 2 hours to obtain a suspension containing the crosslinked acrylic resin particles (polymerization step). During the suspension polymerization, the polymerization atmosphere was set to a nitrogen atmosphere.

After the obtained suspension was cooled to 20 캜, hydrochloric acid was added to the suspension to decompose the tribasic calcium phosphate, and then the crosslinked acrylic resin particles were separated using a centrifugal separator (manufactured by Danabe Wilted Co.), and the obtained crosslinked acrylic resin particles Was washed with ion exchange water.

Next, the obtained crosslinked acrylic resin particles were dried at 60 캜 under a vacuum degree of 0.05 MPa for 15 hours (drying step). The volume average particle diameter of the obtained crosslinked acrylic resin particles was 8.21 탆.

A wind power classifier (trade name " Hi-bolter NR300 ", trade name, manufactured by Toyobo Co., Ltd.) having a screen with a scale interval of 32 mu m was prepared. The crosslinked acrylic resin particles were classified in an air atmosphere having a relative humidity of 20% by using a wind power classifier. The crosslinked acrylic resin particles were loaded on a stream of air having a relative humidity of 20% to impinge the crosslinked acrylic resin particles on the screen, and particles not passing through the mesh of the screen were removed to remove particles having a large particle size to obtain crosslinked acrylic resin particles .

(Example 2)

Crosslinked acrylic resin particles were obtained in the same manner as in Example 1 except that the raw material monomer containing 47.5 parts by weight of methyl methacrylate and 2.5 parts by weight of ethylene glycol dimethacrylate was used.

(Example 3)

5 parts by weight of calcium pyrophosphate as an inorganic dispersion stabilizer and 0.005 part by weight of sodium lauryl sulfate as an anionic surfactant were added to 100 parts by weight of deionized water to form an aqueous phase.

On the other hand, to the raw material monomer containing 20 parts by weight of methyl methacrylate and 20 parts by weight of ethylene glycol dimethacrylate, 40 parts by weight of methyl ethyl ketone as an organic solvent and 40 parts by weight of 2,2'-azobisisobutyronitrile 0.1 part by weight was dissolved into an oil phase.

The aqueous phase and the aqueous phase were stirred and mixed at a rotation speed of 3000 rpm using a dispersing machine (trade name "TK Homomixer MODEL S", manufactured by FRIMICS Co., Ltd.), and an oil phase droplet was dispersed in the aqueous phase to obtain a dispersion. After the dispersion was fed to a polymerization reactor equipped with a stirrer and a thermometer, the dispersion was heated to 50 캜 (first temperature region) while stirring the dispersion, and the raw monomer was subjected to suspension polymerization for 5 hours. Subsequently, the dispersion was heated to 70 DEG C (second temperature region) and the raw monomer was subjected to suspension polymerization for 2 hours to obtain a suspension containing crosslinked acrylic resin particles (polymerization step). During the suspension polymerization, the polymerization atmosphere was set to a nitrogen atmosphere. The suspension containing the crosslinked acrylic resin particles was distilled under the conditions of 85 캜 and a degree of vacuum of 0.063 MPa to remove methyl ethyl ketone from the suspension.

After the obtained suspension was cooled to 20 캜, hydrochloric acid was added to the suspension to decompose the calcium pyrophosphate, and then the crosslinked acrylic resin particles were separated using a centrifugal separator (manufactured by Danabe Wilted Co.), and the obtained crosslinked acrylic resin particles Ion-exchanged water.

Next, the obtained crosslinked acrylic resin particles were dried for 24 hours under the conditions of 90 캜 and a degree of vacuum of 0.07 MPa (drying step). The volume average particle diameter of the obtained crosslinked acrylic resin particles was 10 μm. The crosslinked acrylic resin particles were porous bodies having a specific surface area of 91 cm < 2 > / g.

A wind power classifier (trade name " Hi-bolter NR300 ", trade name, manufactured by Toyobo Co., Ltd.) having a screen with a scale interval of 32 mu m was prepared. The crosslinked acrylic resin particles were classified in an air atmosphere having a relative humidity of 20% by using a wind power classifier. The crosslinked acrylic resin particles were loaded on a stream of air having a relative humidity of 20% to impinge the crosslinked acrylic resin particles on the screen, and particles not passing through the mesh of the screen were removed to remove particles having a large particle size to obtain crosslinked acrylic resin particles . The weight loss of the obtained crosslinked acrylic resin particles was 0.65%.

(Lamy house AL-14, trade name, manufactured by Seisan Japan) having a laminated film (vapor permeability: 0.7 g / m < 2 > 24 hours) in which a metal film was laminated and integrated on one surface of a synthetic resin film, 50 g of the crosslinked acrylic resin particles obtained in the bag were contained and sealed to produce a packaged article. The packaged product was allowed to stand in a thermo-hygrostat (trade name " TBE " manufactured by Especa) adjusted to a relative humidity of 80% at 30 캜 for 24 hours. Thereafter, the packaged article was opened, and the heating loss of the crosslinked acrylic resin particles contained in the bag was measured and found to be 0.66%.

(Example 4)

A separable flask equipped with a stirrer, a thermometer and a reflux condenser was charged with a reaction solution containing 60 parts by weight of ion-exchanged water, 10 parts by weight of methyl methacrylate and 0.05 part by weight of n-dodecylmercaptan as a polymerization regulator, While the flask was purged with nitrogen, and the reaction solution was heated to 70 캜. While maintaining the reaction liquid in the flask at 70 占 폚, 0.05 parts by weight of potassium persulfate as a polymerization initiator was fed to the reaction liquid, and the reaction liquid was polymerized for 20 hours to obtain an emulsion (A). The obtained emulsion (A) contained solid content of 14% by weight. The solid component contained spherical particles having a volume average particle diameter of 0.4 占 퐉.

A separate reaction flask equipped with a stirrer, a thermometer and a reflux condenser was charged with 55 parts by weight of water, 7 parts by weight of the emulsion (A), 10 parts by weight of methyl methacrylate and 0.05 part by weight of n-dodecylmercaptan And the inside of the flask was purged with nitrogen while stirring the reaction solution, and the temperature of the reaction solution was raised to 70 占 폚. 0.05 parts by weight of potassium persulfate as a polymerization initiator was fed to the reaction liquid while maintaining the reaction liquid in the flask at 70 DEG C, and then the reaction liquid was polymerized for 12 hours to obtain an emulsion (B). The obtained emulsion (B) contained solid content of 14% by weight. The solid component contained spherical particles (seed particles) having a volume average particle diameter of 1.0 mu m.

In a separate separable flask equipped with a stirrer, a thermometer and a reflux condenser, 40 parts by weight of methyl methacrylate, 30 parts by weight of ethylene glycol dimethacrylate and 30 parts by weight of styrene as raw material monomers were mixed with 2,2'-azobis 6 parts by weight of isobutyronitrile were fed and uniformly mixed to obtain a mixture.

100 parts by weight of ion-exchanged water containing 1 part by weight of sodium succinic acid sulphate as a surfactant was supplied to the obtained mixture, and the mixture was stirred at 20,000 rpm for 20 minutes using a dispersing machine (trade name: TK HOMOMIXER MODEL S, Lt; 0 > C to obtain a water-based emulsion. 8 parts by weight of the emulsion (B) was added to this aqueous emulsion with stirring to prepare a dispersion.

Stirring of the dispersion was continued at 20 캜 for 3 hours, and the dispersion was observed under an optical microscope. As a result, the raw material monomer in the dispersion was absorbed by the seed particles (swelling magnification of about 20 times). Next, 200 parts by weight of the dispersion stabilizer aqueous solution was supplied to the dispersion. The dispersion stabilizer aqueous solution was prepared by dissolving 4 parts by weight of polyvinyl alcohol (trade name "PVA-224E", manufactured by Kuraray Co., Ltd.) as a dispersion stabilizer in 196 parts by weight of ion exchange water. The raw material monomer was polymerized at 60 캜 (first temperature region) over 6 hours while stirring the dispersion. Subsequently, the dispersion was heated to 100 ° C (second temperature region) and the raw monomer was polymerized for 3 hours to obtain a suspension containing the crosslinked acrylic resin particles (polymerization step). During the polymerization, the polymerization atmosphere was set to a nitrogen atmosphere.

The resulting suspension was cooled to 20 DEG C, and the crosslinked acrylic resin particles were filtered and separated using a pressure filter, and the resulting crosslinked acrylic resin particles were washed with ion exchange water.

Next, the obtained crosslinked acrylic resin particles were dried at 60 캜 under a vacuum degree of 0.05 MPa for 15 hours (drying step). The volume average particle diameter of the obtained crosslinked acrylic resin particles was 5.01 탆.

The classification of the crosslinked acrylic resin particles was carried out in an atmosphere of a relative humidity of 25% using a wind power classifier (trade name: "Turbo Classifier TC-15" manufactured by Nissei Engineering Co., Ltd.). Concretely, the crosslinked acrylic resin particles are loaded on the swirling airflow generated by the conditions of the rotor rotational speed of 4,500 rpm and the air flow rate of 2.0 m < 3 > / min, and the centrifugal force applied to the particles by the swirling air stream By the interaction of the air current flow, large particles were removed by dividing the particles with large particles and small particles through the sieve to obtain crosslinked acrylic resin particles.

(Comparative Example 1)

Crosslinked acrylic resin particles were obtained in the same manner as in Example 2 except that the polymerization time of the raw material monomer at 55 캜 (first temperature region) was 8 hours.

(Comparative Example 2)

Crosslinked acrylic resin particles were obtained in the same manner as in Example 3 except that classification of the crosslinked acrylic resin particles was carried out in an atmosphere of air having a relative humidity of 80%.

(Comparative Example 3)

Crosslinked acrylic resin particles were obtained in the same manner as in Example 1 except that the classification step was not performed.

(Comparative Example 4)

Crosslinked acrylic resin particles were obtained in the same manner as in Example 4 except that the polymerization time of the raw material monomer at 60 캜 (first temperature region) was 8 hours and the classification step was not performed. The volume average particle diameter of the obtained crosslinked acrylic resin particles was 5.03 탆.

The crosslinked acrylic resin particles thus obtained were measured for heat loss, volume-average particle size and content of particles (large-diameter particles) having a particle size of not less than twice the volume-average particle size after heating at 120 ° C for 1.5 hours, Are shown in Table 1. The surface properties of the coating film obtained from the resin composition containing the obtained crosslinked acrylic resin particles were measured in the following manner, and the results are shown in Table 1.

(Surface property of coated film)

, 0.4 part by weight of crosslinked acrylic resin particles, 2.5 parts by weight of a polyester resin (trade name "VYLON 200", manufactured by TOYOSETTON CORPORATION), 5.0 parts by weight of toluene and 1.0 part by weight of methyl ethyl ketone were added to a stirring deaerator (trade name " Taro ") and mixed for 3 minutes, followed by defoaming for 1 minute to prepare a resin composition.

The obtained resin composition was coated on a black ABS plate to a thickness of 100 占 퐉, and the coating film was dried in an oven at 70 占 폚 for 3 minutes to prepare a coating film. The obtained coating film surface was visually observed and judged based on the following criteria.

A ... No protrusions or stains were observed.

B ... A few protrusions or stains were observed.

C ... Many protrusions or stains were observed.

(Preparation of resin composition for antiglare film and production of antiglare film)

[Production Example 1]

80 parts by weight of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (Aronix (registered trademark) M-305, manufactured by Toagosei Co., Ltd.) as an ultraviolet ray curable resin and 80 parts by weight of toluene and cyclopenta , 120 parts by weight of a mixed liquid (toluene: cyclopentanone (volume ratio) = 7: 3), 5 parts by weight of the crosslinked acrylic resin particles prepared in Example 4 and (2-methyl- Phenyl) -2-morpholinopropane-1-one) (trade name: Irgacure (registered trademark) 907, manufactured by BASF Japan) were mixed to prepare a resin composition for an antiglare film.

As a transparent film substrate, a transparent polyethylene terephthalate (PET) film having a thickness of 200 mu m was prepared. A resin composition for an antiglare film was applied to one side of a polyethylene terephthalate film using a bar coater to form a coating film. Next, the coating film was heated at 80 DEG C for 1 minute to dry the coating film. Thereafter, ultraviolet rays were irradiated to the coated film at an accumulated light quantity of 300 mJ / cm 2 using a high-pressure mercury lamp to cure the coated film to form a flash-resistant hard coat layer. An antiglare film in which a light-scattering hard coat layer containing the crosslinked acrylic resin particles of Example 4 was laminated and integrated on one side of a polyethylene terephthalate film was obtained.

[Comparative Production Example 1]

An antiglare film was obtained in the same manner as in Production Example 1 except that the crosslinked acrylic resin particles of Comparative Example 4 were used instead of the crosslinked acrylic resin particles of Example 4.

The antiglare property, total light transmittance and haze of the obtained antiglare film were measured in the following manner, and the results are shown in Table 2.

(Repellency)

The antiglare film was placed just under the fluorescent lamp so that the surface of the antiglare film was visually observed and evaluated based on the following criteria. Further, a fluorescent lamp was disposed at a position 50 cm above and above the surface of the antiglare film.

A ... The outline of the fluorescent lamp looked blurry.

B ... The outline of the fluorescent lamp was visible, and the contour was a little nervous.

C ... The outline of the fluorescent light was clear.

(Total light transmittance and haze)

The total light transmittance of the antiglare film was measured according to JIS K7361-1, and the haze of the antiglare film was measured according to JIS K7136. Specifically, the total light transmittance and haze of the antiglare film were measured using a haze meter (NDH2000) available from Nippon Seishoku Kogyo Co.,

Claims (10)

And a content of large-diameter particles having a particle diameter of not less than 2 times the volume-average particle size of not more than 1.0% by volume is contained in an amount of not more than 1.5% after heating at 120 ° C for 1.5 hours, . The method according to claim 1,
Wherein the volume average particle diameter is 50 占 퐉 or less. The method according to claim 1,
A crosslinked acrylic resin particle characterized by being porous. The method according to claim 1,
Wherein the acrylic resin is crosslinked by an acrylic polyfunctional monomer having a plurality of (meth) acryloyl groups, and the acrylic polyfunctional monomer is produced by a dehydration esterification method and purified by distillation Acrylic resin particles. A polymerization step of polymerizing raw monomers including an acrylic monomer and a polyfunctional monomer in a first temperature range and then further polymerizing in a second temperature range higher than the first temperature range to produce crosslinked acrylic resin particles;
A drying step of drying the crosslinked acrylic resin particles obtained in the polymerization step under a condition of a degree of vacuum of 0.03 to 0.09 MPa and a temperature of 30 to 90 캜,
The crosslinked acrylic resin particles dried in the drying step are classified into a class such that the content of large diameter particles having a particle size of 2 times or more of the volume average particle diameter is 1.0 volume% or less in an atmosphere having a relative humidity of 30% Wherein the cross-linked acrylic resin particles have an average particle size of not more than 50 占 퐉. 6. The method of claim 5,
Wherein the first temperature range is 30 ° C or higher and lower than 80 ° C, and the second temperature range is 80 ° C to 120 ° C. A resin composition comprising a binder resin and crosslinked acrylic resin particles according to any one of claims 1 to 4. An optical film obtained by applying the resin composition of claim 7 onto a transparent film substrate. 9. The method of claim 8,
Wherein the optical film is an antiglare film. A packaged article characterized in that the acrylic resin particle of any one of claims 1 to 4 is sealed with a packaging material having a water vapor permeability of 50 g / m 2 24 hours or less.