KR100789046B1 - Process for Preparing Monodisperse Spherical Light Diffuser - Google Patents

Abstract

The present invention relates to a method for preparing a monodisperse light diffusing agent by polymerizing a large diameter crosslinked seed particle by non-emulsion polymerization and performing a single swelling process, and more specifically, using a mixed dispersion medium to prepare a seed. The present invention relates to a method for preparing a monodisperse light diffusing agent of various sizes by preparing a non-emulsified polymerization, undergoing a single swelling process using the crosslinked seed, and then polymerizing the crosslinked particles.

Crosslinked seed particles, crosslinked fine particle polymerization, monodisperse light diffusing agent

Description

Process for Preparing Monodisperse Spherical Light Diffuser

Figure 1 shows the results of observing the microparticles prepared by seeding the cross-linked seed with an electron microscope.

The present invention relates to a method for preparing a monodisperse light diffusing agent by preparing large-diameter crosslinked seed particles by non-emulsification polymerization and polymerizing them through a single swelling process.

The present invention relates to a light diffusing film used for a projection television dedicated projection screen, a light diffusing plate for liquid crystal backlight, a light diffusing sheet, or an illumination shade. Projection televisions, liquid crystal displays, and the like are used in light diffusing plates and light diffusing films to uniformly diffuse light from a light source.

The light diffusing film is composed of transparent resin and light diffusing particles dispersed in the resin. As light-diffusing particles contained in such light-diffusion films, inorganic powders such as barium sulfate, calcium carbonate, titanium oxide, silica, alumina, glass powder, and the like have been conventionally used. However, the inorganic powder is not spherical in shape, irregular in particle size is common, uniform light diffusion is difficult, and the surface of the light diffusing film itself is covered with inorganic powder and roughened, and light transmittance is low. There was a problem of eggplant. Under these circumstances, it is proposed to use resin particles instead of inorganic particles. Even when such resin particles are used, the light diffusion characteristics are not necessarily satisfied.

The light diffusing film has been used to allow the light (surface light source) irradiated from the light source to diffuse more uniformly through the light guide plate, but it has been attempted to improve the brightness of the liquid crystal display by the improved diffusion film. The light diffusing resin particles contained in the light diffusing film have been tried to improve the luminance by adjusting the coefficient of variation (CV) of the average particle diameter and the particle size distribution.

There are several methods for producing light diffusion resin particles, including dispersion polymerization and non-emulsion polymerization, which are used to make seeds. And there is seed polymerization which superposes | polymerizes using a seed.

Dispersion Polymerization is a vinyl monomer, a polymerization initiator, a steric stabilizer, which is a high molecular material, and an organic solvent as constituents of the polymerization reaction.In the initial stage of the reaction, all reaction components are dissolved in the organic solvent and are in a transparent phase. Although the number of is 1, as the polymerization proceeds, the polymer whose molecular weight increases is precipitated without dissolving in the organic solvent, and refers to a polymerization method in which spherical particles are obtained in the size of several hundred nm to several tens of micrometers by the steric stabilizer present.

Soap Free Emulsion Polymerization is a vinyl monomer, a water-soluble polymerization initiator, water, and an organic solvent as a reaction medium. In the reaction vessel, oligomers reacted with a water-soluble polymerization initiator form micelles to become nuclei, and the reaction proceeds with an emulsion polymerization mechanism. It refers to a polymerization method in which the particles are swollen by an organic solvent after the middle of the reaction so that spherical particles are obtained in the size of several hundred nm to several tens of m.

Seeded Polymerization is an efficient method for producing monodisperse polymer particles having a uniform size of 1 to 50 μm that are difficult to prepare by emulsion polymerization, dispersion polymerization and suspension polymerization. There are two general methods for such seed polymerization, one of which is Uglestade [Advanced in Colloid and Interface Science, 13 (1980) 101-140; J. Ugelstad, P.C. This method uses a two-stage swelling process developed by Mork, which swells the seed particles primarily by oligomers or organic solvents and then swells by monomers. There are complex drawbacks as two steps. Another method is to use a dynamic swelling process developed by Okubo (European Patent No. 0326383; M. Okubo), which is an organic solvent in which seed particles are dissolved in monomers, dispersion stabilizers, and reaction initiators. After dispersing in water, water is slowly added to lower the solubility of the monomer so that the monomer is adsorbed to the seed.

The spherical polymer particles having a size of several μm thus synthesized are used as standard materials for measuring the device, measuring the size and efficiency of the filter pores, packing materials for the column for chromatography, support in biochemistry, biomedical field, coating, It is applied to various fields of high value added such as ink, dry toner for copying, information industry and fine electronics.

The particle size variation coefficient (CV) of a polymer particle is a value which takes a photograph by an electron microscope, and measures with respect to arbitrary 250 particle | grains of this image using an image analyzer (Image Analyzer), and calculates according to following Formula.

Coefficient of variation (CV) = standard deviation of particle size (σ) / particle size (Dn)

Standard Deviation of Particle Size (σ) = (Di-Dn) / (n-1) x Dn

Di = particle diameter of each particle, n = 250

Such light diffusing resin particles can be divided into a polydisperse light diffusing agent and a monodisperse light diffusing agent. There are several patents for monodisperse light diffusing agents. In Japanese Patent Laid-Open No. 7-234304, a method of obtaining a size of 10 µm or more by using a cross-linked seed and polymerizing the swelling process in six steps is required, but a multi-step swelling process is required. In Japanese Patent Laid-Open No. 8-120005, a method for obtaining a size of 10 μm or more by using a crosslinked seed and polymerizing the swelling process in three steps is required, but a multistage swelling process is required. Japanese Unexamined Patent Application Publication No. 2000-191708 proposes to form a non-crosslinked seed and to polymerize it through a single swelling, but the seed is swelled and polymerized without crosslinking to be a problem in the solvent resistance of the light diffusing agent. In Japanese Patent Laid-Open No. 2004-226604, a method of obtaining a size of 10 µm or more by using a non-crosslinked seed and polymerizing the swelling process in three steps may be problematic in solvent resistance of the light diffusing agent.

These methods have problems. First, in order to produce particles having a size of 10 μm or more, a multi-step swelling process is required. Second, the swelling process is one time, but the solvent resistance is bad using non-crosslinked seed.

Accordingly, the present inventors have developed a method for producing a monodisperse light diffusing agent having a size of 10 μm or more by preparing a large-diameter crosslinked seed using an emulsion-free polymerization method and polymerizing it through a single swelling process.

It is an object of the present invention to provide a method for producing a monodisperse light diffusing agent having excellent solvent resistance and having a size of 10 µm or more in a single swelling and having a coefficient of variation (CV) of less than 10%.

In order to achieve this purpose, a large diameter crosslinked seed having a size of 0.1 to 5 μm is prepared, and the crosslinked fine particles are polymerized through a single swelling process using the crosslinked seed.

In addition, the present invention provides a method for preparing a monodisperse light diffusing agent having a viscosity of 30 Cp or less, a size of 10 μm or more, and a coefficient of variation (CV) of 10% or less measured after 24 hours after dispersing the crosslinked fine particles in toluene. The purpose is.

Method for producing a monodisperse light diffusing agent according to the present invention,

(a) 100 parts by weight of the first monofunctional monomer, 0.001 to 10 parts by weight of the first polyfunctional monomer, 0.01 to 10 parts by weight of the first polymerization initiator, and 500 to 2000 parts by weight of the mixed dispersion medium to synthesize seed particles. ; And

(b) 1 to 50 parts by weight of the second polyfunctional monomer, based on 10 to 200 parts by weight of the second monofunctional monomer, and 100 parts by weight of the second monofunctional monomer, based on the seed particles and 1 part by weight of the seed particles; 0.1 to 10 parts by weight of a polymerization initiator, 0.1 to 10 parts by weight of a dispersion stabilizer, and 100 to 1000 parts by weight of a water-soluble medium, followed by swelling, followed by polymerization to prepare crosslinked fine particles;

Characterized in that it comprises a.

Preferably, the average particle diameter of the seed particles formed by the step (a) is 0.1 ~ 20㎛, the coefficient of variation (CV) is 10% or less.

In addition, the average particle diameter of the crosslinked fine particles formed by the step (b) is 0.5 ~ 100㎛, the coefficient of variation (CV) is preferably 10% or less.

Preferably, the crosslinking content of the seed particles is characterized in that 0.01 to 0.5%.

Preferably, the first monofunctional monomer and the second monofunctional monomer are the same or different from each other, and are selected from the group consisting of styrene compounds, cyan vinyl compounds, acrylate compounds, methacrylate compounds, and mixtures thereof. It is characterized by.

Further, the first polyfunctional monomer and the second polyfunctional monomer are preferably the same or different from each other, and are selected from the group consisting of aromatic vinyl crosslinkable monomers, acrylic crosslinkable monomers, and mixtures thereof.

Preferably, the mixed dispersion medium is characterized in that a mixture of water and an organic solvent.

Preferably, the first polymerization initiator is selected from the group consisting of potassium persulfate, ammonium persulfate and mixtures thereof.

In addition, the second polymerization initiator is preferably selected from the group consisting of azo compounds, peroxides, percarbonate compounds, perester compounds, and mixtures thereof.

Preferably, the dispersion stabilizer is polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyethyleneamine, polyacrylic acid, polyvinylacetate, polyvinylacetate copolymer, polyethylcellulose, polyhydroxypropylcellulose and these It is characterized in that it is selected from the group consisting of.

The monodisperse light diffusing agent produced by the method according to the invention is characterized in that the average particle diameter of the crosslinked fine particles is 0.5 to 100 µm and the coefficient of variation (CV) is 10% or less.

It is preferable that the crosslinked fine particles are dispersed in toluene, and the viscosity measured after 24 hours at 70 ° C is 30 cP or less.

The manufacturing method of the polymer particle of this invention is demonstrated concretely. The method for producing the polymer particles of the present invention may be divided into a seed particle production step and a light diffusion agent polymerization step subsequent to the seed particle production step.

1) First seed particle synthesis step (seed synthesis)

This seed particle can be formed with various resin.

The monomers used in carrying out the polymerization method according to the present invention are based on the styrene-based compound, which is an aromatic vinyl-based cyan-based compound, an acrylate-based vinyl compound, and a methacrylate-based vinyl compound in the presence of a styrene-based compound. Compounds can be mixed and used. For example, styrene, divinylbenzene, ethylvinylbenzene, alphamethyl styrene, fluorostyrene, vinylpyridine, and the like are included in the aromatic vinyl compound, and the above monomers may be used alone or in combination of two or more thereof. Cyanide vinyl compounds such as acrylonitrile and methacrylonitrile Butyl acrylate compounds such as butyl acrylate, 2-ethylhexyl ethyl acrylate, glycidyl acrylate, N, N'-dimethylaminoethyl acrylate Methacrylate-based compounds such as acrylate, 2-ethylhexylethyl methacrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, polyethylene glycol diacrylate, 1,3-butyl Diacrylate type compounds, such as ethylene glycol diacrylate and 1, 6- hexanediacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate And dimethacrylate-based compounds such as 1,3-butylene glycol dimethacrylate and the like.

The seed particles used in the present invention may be copolymerized in a range in which a component copolymerizable with the monomer does not impair the properties of the seed particles. The crosslinked structure is formed in the seed particles, the crosslinking content is preferably in the range of 0.01 to 0.5%, and preferably in the range of 0.05 to 0.2%.

Thus, in order to adjust the crosslinking degree of seed particle | grains, an aromatic vinyl crosslinkable monomer and an acrylic crosslinkable monomer are used as a polyfunctional monomer, and a crosslinked structure is formed. Examples of the polyfunctional monomer include ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimetholpropane trimethacrylate, 1,1,1-trihydroxymethyl ethane Acrylate, 1,1,1-trihydroxymethyl ethanetriacrylate, 1,1,1-trihydroxymethylpropanetriacrylate, divinylbenzene, but is not particularly limited thereto.

When forming seed particles, the polyfunctional monomer is used in an amount of 0.001 to 10 parts by weight, preferably 0.01 to 0.1 parts by weight based on 100 parts by weight of the monomer.

In particular, the seed particle forming step used in the present invention is characterized in that it uses a mixed dispersion medium in which water and an organic solvent are mixed. The definition of the mixed dispersion medium is similar to that of the dispersion polymerization, with the same point that the mixed dispersion medium and the monomer are mixed to form a homogeneous phase before the reaction, and the chain grows during the reaction to form a heterogeneous phase (heterogeneous). It is achieved. Although the growth mechanism of the seed particles used in the present invention can be described as the growth mechanism of dispersion polymerization, the nucleation process is the theory of micellar nucleation of emulsification polymerization and the single phase of dispersion polymerization. It does not match the theory of homogeneous nucleation. In addition, the particle size distribution of non-emulsified polymerization has a lot of fine powder and coarse powder, but the non-emulsion polymerization under mixed dispersion medium containing organic solvent is characterized in that fine powder and coarse powder are greatly reduced. In summary, in the present invention, the seed particles are synthesized according to the non-emulsification polymerization method having an intermediate property, which is neither emulsion-free polymerization nor dispersion polymerization.

In preparing a suspension containing seed particles according to the present invention, a polymerization initiator is used. Examples of the polymerization initiator used herein include potassium peroxide, ammonium persulfate, and the like. The initiator used is usually used in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the monomer.

If the amount is less than 0.01 parts by weight, the rate of the polymerization reaction is significantly reduced and there is a problem that gelation occurs due to auto-acceleration when more than 10 parts by weight.

In this invention, it is not specifically limited as a mixed dispersion medium, It is possible to use the conventionally well-known solvent used for precipitation polymerization, For example, the mixed-solvent of water and an organic solvent is mentioned.

As said organic solvent, it is preferable to use what melt | dissolved a polymerizable monomer but does not melt a produced polymer. Although such a solvent can be appropriately selected according to the polymerizable monomer, for example, alcohols such as methanol, ethanol, propanol and butanol, methyl cellosolves such as methanol, cellosolves such as ethyl cellosolve, acetone, methyl ethyl ketone, and methyl Ketones such as butyl ketone; And in addition, benzene, toluene, xylene, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide and the like are used. One or more of these organic solvents are selected and used in admixture with water. The mixed dispersion medium is usually used in an amount of 500 to 2000 parts by weight based on 100 parts by weight of the monomer. Preferred is used in an amount of 1000 to 1500 parts by weight.

The seed particles thus formed are usually 0.1 to 20 µm, and the particle size variation coefficient (CV) of the seed particles thus obtained is 10% or less, preferably 5% or less.

The process for preparing seed particles as described above is described as seed particle synthesis step. The seed particles obtained in the primary seed particle synthesis step are absorbed into the monomer dispersed in the aqueous medium, and the polymerization process is performed only once. This process is described as the secondary seed polymerization step, ie, the preparation of crosslinked particles.

2) Second Seed Polymerization Step (Preparation of Crosslinked Fine Particles; Preparation of Light Diffusion Agent)

The step of synthesizing the crosslinked fine particles is carried out by mixing seed particles, monofunctional monomers, polyfunctional monomers, polymerization initiators, and dispersion stabilizers in an aqueous medium, followed by swelling and polymerization.

The monofunctional and polyfunctional monomers used in the crosslinking seed synthesis step may be the same as or different from the monofunctional and polyfunctional monomers used in the seed particle synthesis.

However, the monomer used in the crosslinking seed preparation step is usually used in an amount of 10 to 200 parts by weight, preferably 20 to 100 parts by weight, based on 1 part by weight of seed particles. That is, the absorption ratio is usually 10 to 200 times the weight, preferably 20 to 100 parts by weight.

In addition, in order to adjust the crosslinked structure and good solvent resistance of the crosslinked particles, polyfunctional monomers are used. Examples thereof include ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tri Metyrol propane trimethacrylate, 1,1,1-tris hydroxymethyl ethane acrylate, 1,1,1-tris hydroxymethyl ethane triacrylate, 1,1,1-tris hydroxymethyl propane tree Acrylate and divinylbenzene, but are not particularly limited thereto.

The polyfunctional monomer is used in an amount of 1 to 50 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the monomer.

Polymerization initiators used herein include peroxide and nitrogen compound based acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, di-isopropyl peroxydicarbonate, di- Peroxides such as 2-ethylhexyl peroxydicarbonate, dioctoxyethyl peroxydicarbonate, t-butyl pioxy neodicarbonate, t-butyl peroxy neodicarbonate, benzoyl peroxide and 2,2-azobisisobutyronitrile And nitrogen compounds such as azobis-2,4, -dimethylvaleronitrile and azobis (4-methoxy-2,4-dimethylvaleronitrile). This polymerization initiator is normally used in the amount of 0.1-10 weight part with respect to 100 weight part of monomers.

Examples of dispersion stabilizers used in the preparation of crosslinked particulates include polyvinyl alcohol, polyacrylic acid, copolymers thereof, and polymethacrylic acid, copolymers thereof. The dispersion stabilizer is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the monomer.

The aqueous medium used in the preparation of the crosslinked fine particles is ion-exchanged water, and its amount is typically 100 to 1000 parts by weight based on 100 parts by weight of the monomer.

After blending the reaction raw materials as described above, the swelling and polymerization process is performed. The monomer is polymerized after being absorbed into the seed particles. In the present invention, secondary polymerization is carried out so as to be 2 to 200 times the weight of the seed particles obtained in the first step. As such, it is common to carry out the second polymerization process two or more times in order to grow the seed particles, but in the present invention, it passes only once.

Preferably, the swelling process is preferably carried out for 1 to 24 hours at a temperature of 10 ~ 40 ℃, but is not particularly limited thereto.

In addition, after swelling, the polymerization is preferably carried out for 3 to 24 hours at a temperature of 60 ~ 80 ℃, but is not particularly limited thereto.

The crosslinked fine particles thus obtained usually have an average particle diameter of 0.5 to 100 µm, preferably 1 to 20 µm, a coefficient of variation (CV) of usually 10% or less, and preferably 1 to 5%.

As a result of observing the crosslinked fine particles obtained in the present invention with an electron microscope, it is a true sphere. Moreover, since it is a crosslinked fine particle using a crosslinking agent, it does not melt | dissolve in organic solvents, such as toluene, ethyl acetate, a phenol, dichloroethane, acetone. The crosslinked fine particles are dispersed in toluene, and the viscosity measured after 24 hours at 70 ° C is 30 cP or less, which is excellent in solvent resistance.

Example

1 is a photograph observed with an electron microscope using the sample obtained in Example 1. The microparticles prepared by Example 1 were washed, dried and classified to obtain a final result.

The final sample was obtained by measuring the particle size (μm) using an electron microscope and randomly selecting 500 to obtain a coefficient of variation (CV). The final fine particles, the organic solvent and the binder resin were mixed and dispersed, and after 24 hours at 70 ° C., the viscosity (cP) was measured using a viscometer.

Example 1

The commercial quality methyl methacrylate was washed with dilute caustic soda solution to remove the polymerization inhibitor, and then the methyl methacrylate was washed with water, and only methyl methacrylate was separated and refrigerated and used as follows.

1) First seed particle synthesis step (seed synthesis)

Into a mixed solution of 400 g of distilled water and 100 g of ethanol, 50 g of methyl methacrylate, 0.5 g of potassium perperate and 0.5 g of ethylene glycol dimethacrylate were placed in a 1 L reactor in a 1 L reactor, heated at 70 ° C., and heated at 70 ° C. at a speed of 100 rpm. After the polymerization was carried out by stirring, the cross-linked seed particles obtained after a predetermined reaction time had a size of 5.4 µm and a coefficient of variation (CV) of 5%.

2) secondary seed polymerization step (light diffusing agent)

Into the same apparatus as above, 5 g of ethylene glycol dimethacrylate and 0.1 g of benzoyl peroxide were added to 100 g of methyl methacrylate as a monomer, and 300 g of distilled water in which 0.1 g of polyvinyl alcohol was dissolved was added. Mix for a minute. Subsequently, 10 g of the seed emulsion prepared in the above-mentioned seed particle production process was added to the mixed solution and swollen at room temperature for 1 hour, and then reacted at 70 ° C. for 6 hours to obtain a fine particle dispersion.

The results of observing the obtained polymerized microparticles with an electron microscope showed an average particle diameter of 20.0 µm and a coefficient of variation (CV) of 5.3%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, a value of 9 to 12 cP was obtained.

Example 2

1) First seed particle synthesis step (seed synthesis)

Into a mixed solution of 400g of distilled water and 100g of ethanol, 50g of methyl methacrylate, 0.5g of potassium perperate and 0.5g of ethylene glycol dimethacrylate were placed in a 1L reactor at 0.005g, and maintained at a nitrogen atmosphere. After the polymerization was carried out by stirring, the cross-linked seed particles obtained after a predetermined reaction time had a size of 5.5 µm and a coefficient of variation (CV) of 4%.

2) secondary seed polymerization step (light diffusing agent)

Next, 5 g of ethylene glycol dimethacrylate and 0.1 g of benzoyl peroxide were added to 100 g of methyl methacrylate, a monomer, and 300 g of distilled water in which 0.1 g of polyvinyl alcohol was dissolved. Under mixing for 10 minutes. Subsequently, 10 g of the seed emulsion prepared in the above-mentioned seed particle production step was added to the mixed solution and swollen at room temperature for 1 hour, and then reacted at 70 ° C for 6 hours to obtain a fine particle dispersion.

The results of observing the obtained polymerized fine particles with an electron microscope showed an average particle diameter of 20.5 µm and a coefficient of variation (CV) of 4.6%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, a value of 24 to 36 cP was obtained.

Example 3

1) First seed particle synthesis step (seed synthesis)

Into a mixed solution of 400 g of distilled water and 100 g of ethanol, 50 g of methyl methacrylate, 0.5 g of potassium perperate and 0.5 g of ethylene glycol dimethacrylate were placed in a 1 L reactor in a 1 L reactor, heated at 70 ° C., and heated at 70 ° C. at a speed of 100 rpm. After the polymerization was carried out by stirring, the cross-linked seed particles obtained after a predetermined reaction time had a size of 5.4 µm and a coefficient of variation (CV) of 5%.

2) secondary seed polymerization step (light diffusing agent)

Into the same device as above, 35 g of ethylene glycol dimethacrylate and 0.1 g of benzoyl peroxide were added to 70 g of methyl methacrylate as a monomer, and 300 g of distilled water in which 0.1 g of polyvinyl alcohol was dissolved was added. Mix for a minute. Subsequently, 10 g of the seed emulsion prepared in the above-mentioned seed particle production process was added to the mixed solution and swollen at room temperature for 1 hour, and then reacted at 70 ° C. for 6 hours to obtain a fine particle dispersion.

The results of observing the obtained polymerized fine particles with an electron microscope showed an average particle diameter of 19.8 µm and a coefficient of variation (CV) of 6.2%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, 6-12 cP value was obtained.

Comparative Example 1 (7 step)

1) First seed particle synthesis step (seed synthesis)

100 g of methyl methacrylate, 1 g of potassium perperate and 1 g of ethylene glycol dimethacrylate were added to 900 g of distilled water in a 5 L reactor and maintained in a nitrogen atmosphere. The mixture was heated to 70 ° C. and stirred at a speed of 100 rpm to carry out polymerization. The crosslinked seed particles obtained after the reaction time had a size of 0.2 µm and a coefficient of variation (CV) of 8.8%.

2) secondary seed polymerization step (light diffusing agent)

In addition to 900 g of distilled water in which 1 g of sodium lauryl sulfate was dissolved in 100 g of the suspension, a mixture of 100 g of methyl methacrylate and 1 g of ethylene glycol dimethacrylate, in which 1 g of benzoyl peroxide was dissolved, was swollen at room temperature for 6 hours, followed by swelling at 70 ° C. The polymerization was carried out for 6 hours to obtain a suspension.

The same seed synthesis was carried out five times in succession to obtain a suspension having an average particle diameter of 8.19 µm and a coefficient of variation (CV) of 11.8%.

To the same apparatus as described above, add 100 g of the suspension to 900 g of distilled water in which 1 g of sodium lauryl sulfate was dissolved, and swell for 6 hours while stirring a mixture of 60 g of methyl methacrylate and 40 g of ethylene glycol dimethacrylate in 1 g of benzoyl peroxide. After reacting at 70 ° C. for 6 hours, a fine particle dispersion was obtained.

The results of observing the obtained polymerized particulates with an electron microscope showed an average particle diameter of 12.9 µm and a coefficient of variation (CV) of 11.6%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, a value of 12 to 24 cP was obtained.

Comparative Example 2 (3 step)

1) First seed particle synthesis step (seed synthesis)

100 g of methyl methacrylate, 0.2 g of potassium perperate, and ethylene glycol dimethacrylate were added to 900 g of distilled water at 0.04 g in a 5L reactor and maintained at a nitrogen atmosphere. After the reaction time, the cross-linked seed particles obtained had a size of 0.5 μm and a coefficient of variation (CV) of 5.3%.

2) secondary seed polymerization step (light diffusing agent)

To 20 g of the suspension was added to 900 g of distilled water in which 1 g of sodium lauryl sulfate and 1 g of polyvinyl alcohol were dissolved, and a mixture of 95 g of methyl methacrylate and 5 g of ethylene glycol dimethacrylate, in which 0.2 g of benzoyl peroxide was dissolved, was stirred at room temperature. After swollen for time, it was made to react at 70 degreeC for 6 hours, and the fine particle dispersion was obtained. As a result, a suspension having an average particle diameter of 1.2 mu m and a coefficient of variation (CV) of 5.8% was obtained.

In the same apparatus as described above, a mixture of 93 g of ethyl acrylate and 7 g of ethylene glycol dimethacrylate was severely added to 900 g of distilled water in which 1 g of sodium lauryl sulfate and 1 g of polyvinyl alcohol were dissolved in 33 g of the suspension. After swelling at room temperature for 6 hours with stirring, the mixture was reacted at 70 ° C for 6 hours to obtain a fine particle dispersion.

As a result of observing the obtained polymerized microparticles with an electron microscope, the average particle diameter was 12.5 µm and the coefficient of variation (CV) was 8.9%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, a value of 24 to 36 cP was obtained.

Comparative Example 3 (2 step)

1) First seed particle synthesis step (seed synthesis)

As an initiator, 2 g of 3,5,5-trimethylhexaperoxide, 0.1 g of sodium lauryl sulfate, and 20 g of distilled water were granulated after ultrasonic emulsification. This aqueous dispersion was absorbed into non-crosslinked seed particles having a size of 1.9 mu m.

2) secondary seed polymerization step (light diffusing agent)

In the same apparatus as above, the suspension was added to 100 g of distilled water in which 2.5 g of polyvinyl alcohol was dissolved, and a mixture of 60 g of styrene and 40 g of trimetholpropane trimethacrylate in which 2 g of t-butylperoxy-2-ethylhesaate was dissolved was added. After swelling at room temperature for 6 hours with vigorous stirring, the mixture was reacted at 70 ° C for 6 hours to obtain a fine particle dispersion.

The results of observing the obtained polymerized microparticles with an electron microscope showed an average particle diameter of 8.8 µm and a coefficient of variation (CV) of 9.1%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, a value of 80 to 100 cP was obtained.

Comparative Example 4 (3 step)

1) First seed particle synthesis step (seed synthesis)

Into 340g of distilled water, 56g of methyl methacrylate, 0.28g of potassium peroxide and 0.26g of normal octylmercaptan were placed in a 1L reactor, maintained in a nitrogen atmosphere, heated to 70 ° C, and stirred at a speed of 100rpm for polymerization. The crosslinked seed particles obtained after the time had a size of 0.5 µm and a coefficient of variation (CV) of 5.0%.

2) secondary seed polymerization step (light diffusing agent)

13 g of the suspension and 350 g of distilled water were mixed and heated to 70, and then 0.19 g of potassium peroxide was supplied.

38 g of methyl methacrylate was added dropwise to the mixed solution for 1 hour, and polymerization was carried out at 70 ° C. for 6 hours to obtain a suspension. As a result, a suspension having an average particle diameter of 1.3 mu m and a coefficient of variation (CV) of 5.8% was obtained.

In the same apparatus as described above, 0.7 g of the suspension was added to 0.16 g of sodium lauryl sulfate and 40 g of distilled water, and 14.8 g of methyl methacrylate, 4.2 g of styrene, dissolved in 0.6 g of azobis-2,4, -dimethylvaleronitrile, The mixture of 2.1 g of divinylbenzenes was swollen at room temperature for 1 hour with vigorous stirring, and then reacted at 70 ° C for 6 hours to obtain a fine particle dispersion.

The results of observing the obtained polymerized fine particles with an electron microscope showed an average particle diameter of 15.3 µm and a coefficient of variation (CV) of 20.1%. The fine particles were washed and dried to obtain a powder. 30 g of the fine particle powder and 70 g of toluene were mixed and swollen at 70 ° C. for 24 hours, and the viscosity thereof was measured. As a result, a value of 180 to 200 cP was obtained.

Seed form (seed bridge) Number of steps Particle Size (㎛) Degree of crosslinking (%) Coefficient of variation (CV) Viscosity (cP) Example 1 Cross-linked seed (0.1%) 2 20.0 5 5.3 9-12 Example 2 Cross-linked seed (0.01%) 2 20.5 5 4.6 24-36 Example 3 Cross-linked seed (0.1%) 2 19.8 30 6.2 6-12 Comparative Example 1 Cross-linked seed (1%) 7 12.9 40 11.6 12-24 Comparative Example 2 Cross-linked seed (0.04%) 3 12.5 7 8.9 24-36 Comparative Example 3 Uncrossed seed 2 8.8 40 9.1 80-100 Comparative Example 4 Uncrossed seed 3 15.3 One 20.1 180-200

As described in detail above, according to the present invention, a monodisperse light diffusing agent having a good solvent resistance, having a size of 10 μm or more with a single swelling and having a coefficient of variation (CV) of 10% or less can be prepared by seed polymerization. It is possible.

Claims (12)

(a) 100 parts by weight of the first monofunctional monomer, 0.001 to 10 parts by weight of the first polyfunctional monomer, 0.01 to 10 parts by weight of the first polymerization initiator, and 500 to 2000 parts by weight of the mixed dispersion medium to synthesize seed particles. ; And (b) 1 to 50 parts by weight of the second polyfunctional monomer, based on 10 to 200 parts by weight of the second monofunctional monomer, and 100 parts by weight of the second monofunctional monomer, based on the seed particles and 1 part by weight of the seed particles; 0.1 to 10 parts by weight of a polymerization initiator, 0.1 to 10 parts by weight of a dispersion stabilizer, and 100 to 1000 parts by weight of a water-soluble medium, followed by swelling, followed by polymerization to prepare crosslinked fine particles; Method of producing a mono-dispersed light diffusing agent comprising a. The method of claim 1, wherein the average particle diameter of the seed particles formed by the step (a) is 0.1 ~ 20㎛, the coefficient of variation (CV) is characterized in that the manufacturing method of the monodisperse light diffuser. The method of claim 1, wherein the average particle diameter of the crosslinked fine particles formed by the step (b) is 0.5 to 100㎛, and the coefficient of variation (CV) is 10% or less. The method of claim 1, wherein the crosslinking content of the seed particles is 0.01 to 0.5%. The method of claim 1, wherein the first monofunctional monomer and the second monofunctional monomer are the same or different from each other, and include a styrene compound, a cyan vinyl compound, an acrylate compound, a methacrylate compound, and a mixture thereof. Method for producing a mono-dispersed light diffusing agent, characterized in that selected from. The method of claim 1, wherein the first polyfunctional monomer and the second polyfunctional monomer is the same or different from each other, characterized in that selected from the group consisting of aromatic vinyl cross-linkable monomers, acrylic cross-linkable monomers, and mixtures thereof. Method for producing monodisperse light diffusing agent. The method of claim 1, wherein the mixed dispersion medium is a mixture of water and an organic solvent. The method of claim 1, wherein the first polymerization initiator is selected from the group consisting of potassium persulfate, ammonium persulfate, and mixtures thereof. The method of claim 1, wherein the second polymerization initiator is selected from the group consisting of azo compounds, peroxides, percarbonate compounds, perester compounds, and mixtures thereof. The method of claim 1, wherein the dispersion stabilizer is polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyethyleneamine, polyacrylic acid, polyvinylacetate, polyvinylacetate copolymer, polyethylcellulose, polyhydroxypropyl cellulose And a mixture thereof, the method of producing a monodisperse light diffusing agent. A monodisperse light diffusing agent prepared by the method according to claim 1, wherein the crosslinked fine particles have an average particle diameter of 0.5 to 100 µm and a coefficient of variation (CV) of 10% or less. The monodisperse light diffusing agent according to claim 11, wherein the crosslinked fine particles are dispersed in toluene, and the viscosity measured after 24 hours at 70 ° C is 30 cP or less.

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