KR20110034237A - Spherical multi-layer large polymer particles with low density and preparation method thereof - Google Patents

Abstract

PURPOSE: A low-density multilayer larger diameter reamer pulverized body is provided to ensure excellent surface state, optical properties, pulverized body flowage, workability and strength. CONSTITUTION: A low-density multilayer larger diameter reamer pulverized body comprises a core layer(a), a void layer(b), and a protective layer(c). The core layer includes vinyl-based monomer of carbon number 2 or more and a polymer of arylmethacrylate and has no voids thereinside. The void layer surrounds the core layer and has pores including a polymer of methylmethacrylate and glycidylmethacrylate. The protective layer surrounds the void layer and includes an acid monomer retarding the contact of a solvent and a polymer of methylmethacrylate.

Description

Low specific gravity large diameter polymer powder and its manufacturing method {SPHERICAL MULTI-LAYER LARGE POLYMER PARTICLES WITH LOW DENSITY AND PREPARATION METHOD THEREOF}

The present invention relates to a multi-layered macromolecular polymer powder having a low specific gravity and a method for manufacturing the same, and more particularly, to provide a powder having a low specific gravity and a large diameter as compared to conventional polymer powders, and thus the process efficiency of the light diffusion plate and sheet, and the product. The present invention relates to a multilayer large-diameter polymer powder capable of improving yield and maintaining a spherical form having a low specific gravity and a method for producing the same.

Spherical polymer powder is spherical in shape and has excellent rheology, which is widely used in various industrial fields such as optical articles, signs, displays, lighting fixtures, cosmetics, paints, and plastic molded articles.

In particular, polymer powders, which are used as light diffusing agents such as light diffusing films and light diffusing plates, which are key components of LCD backlight units (BLUs), generally have a light diffusing effect due to a difference in refractive index between a film, a binder, and a matrix of light diffusing plates. For this purpose, polymethyl methacrylate, polystyrene, and the like have been mainly used. In addition, the size of the light diffusing agent used to exhibit a variety of optical properties has become very diverse recently, the use of a light diffusing agent having a size of 20um or more is increasing. The reason that the large-diameter powder is attracting attention is that as the size of the polymer powder which can be used as the light diffusing agent increases, the lens effect increases, which may contribute to the increase in the brightness of the light diffusing sheet or the light diffusing plate.

However, the biggest reason for the large diameter powder was not sufficiently satisfied was the precipitation occurred in the crude liquid for sheet production as the size of the powder increases, reducing the process efficiency and thereby reducing the yield. For example, in the method of manufacturing a light diffusion sheet, the existing polymethyl methacrylate powder is a light diffusion agent that is mixed with a binder in a light diffusion film and coated in a microgravure method, which is precipitated in a crude liquid depending on the particle size. It is generated and generally subjected to pretreatment in the crude liquid tank with agitation. However, the method cannot effectively control the light diffusing agent precipitated with the change over time, and there is a need for improvement.

To this end, in the case of a light diffusion plate, a product that can reduce the amount of use by using an inorganic light diffusing agent having a low specific gravity while showing the same light scattering and diffusing effect is introduced and used, but there is still no product having a low specific gravity for organic materials. It is not possible.

In order to solve the problems of the prior art as described above, the present invention uses the alkyl meta (a) acrylate that has been used in the manufacture of the conventional polymer powder to make a free volume space in the molecular structure of the conventional methyl meta ( It is an object of the present invention to provide a low specific gravity polymer powder and a method for producing the same.

In addition, the present invention is to provide a large diameter low specific gravity polymer powder having a size of 100um or more by introducing a foam layer in at least one layer of a multi-layer structure and a method of manufacturing the same.

Another object of the present invention is to provide a spherical low specific gravity multilayer polymer powder having a very low specific gravity, a good surface condition, and almost no impurities, and a method for producing the same.

The present invention

A core layer having no internal voids containing a polymer of at least 2 vinyl monomers and aryl methacrylate,

A pore layer surrounding the core layer and having pores containing polymers of glycidyl methacrylate and methyl methacrylate formed in a shell form on the outside, and

A protective layer containing a polymer of an acid monomer and methyl methacrylate formed on the outside and delaying contact of the solvent surrounding the pore layer

It is to provide a spherical low specific gravity multilayer polymer powder comprising a.

The present invention also provides

(A) emulsion core polymerization in the presence of a vinyl monomer having 2 or more carbon atoms and aryl methacrylate to form a core layer having no internal voids,

(B) polymerizing in the presence of glycidyl methacrylate, methyl methacrylate and a blowing agent to form a pore layer having pores on the outer surface of the core layer,

(C) polymerizing in the presence of an acid monomer and methyl methacrylate to form a protective layer on the outer surface of the pore layer to prepare a polymer powder having a three-layer structure of a core layer, a pore layer, and a protective layer from the inside; ,

A method for producing spherical low specific gravity multilayer polymer powder having an average particle diameter of 30 to 200 µm, a coefficient of variation (C.V value) of 20% or less, and a specific gravity of 1.20 or less.

In the following, the present invention is described in more detail.

In the conventional method for preparing low specific gravity particles, low specific gravity particles are prepared by forming voids or secondary thermal expansion through a foaming material, or low specific gravity particles are mixed by using a monomer having a low specific gravity. However, these methods have been found to have limitations in producing large diameters while maintaining low specific gravity.

Accordingly, in the present invention, a multi-layer large diameter having a core layer (a in FIG. 1) without internal voids, a void layer (b in FIG. 1) having internal pores thereon, and a protective layer (c in FIG. 1) over the inner void layer Provided are methods for producing low specific gravity particles.

In particular, according to the present invention, by inducing a chemical bond between the acrylate monomers of each layer, as shown in Figure 2, it is characterized in that to strengthen the interlayer bonding strength to prevent the separation of the layer and the resulting mechanical and chemical properties do.

According to another embodiment of the present invention, the multi-layered structure may include one or more foaming pore layers on the inner core layer.

The core layer (a) having no internal voids is necessary for improving solvent resistance. When only the pore layer is introduced without a relatively dense core layer, the contact surface between the polymer particles and the solvent becomes large and not only swells easily but also dissolves after swelling. However, if a dense structure is introduced into the core layer, only the pore layer (b) may swell, thereby preventing further viscosity increase and contributing to stabilization of the coating process.

The pore layer (b) may provide a space in the molecular structure to impart low specific properties and foam. This prevents the immersion of large diameter particles in the preparation of the coating bath solution to ensure the stability of the bath solution, thereby contributing to the coating process optimization.

The protective layer (c) delays contact between the crude liquid production initial pore layer (b) and the solvent to prevent rapid increase in viscosity, and ensures mechanical properties and storage stability of the particles.

The approximate concept of such multilayer large diameter low specific gravity particles is as shown in FIG. 3.

The present invention specifically introduces arylmethacrylate into a general suspension polymerization process to form a core layer free of internal voids. Aryl methacrylate having a smaller interfacial energy than methyl methacrylate is located on the surface as shown in FIG.

Thereafter, glycidyl methacrylate is introduced into the core layer particles of (a ') in the second step to polymerize, thereby forming a void layer (b') having internal pores on the core layer. In the present invention, the reaction for forming the void layer (b ') on the core layer (a') is a double bond polymerization reaction (Fig. 4a).

Finally, in the present invention, the acid monomer is added to the pore layer (b ') and thermally polymerized to form a protective layer (c') on the pore layer. Thermal polymerization for forming the protective layer (c ') on the pore layer (b') follows the epoxy thermosetting mechanism of glycidyl groups and acids (Fig. 4b).

That is, in the present invention, in the first step, an emulsion is prepared by the homogenization suspension polymerization method using a vinyl monomer having an alkyl group having 2 or more carbon atoms and aryl methacrylate as a specific monomer, and the polymer is obtained by polymerizing the emulsion. It was confirmed that the method of lowering specific gravity by forming a free volume space structurally is very effective. Furthermore, the inventors of the present invention confirmed that, when the same polyfunctional monomer is used to form a three-dimensional network structure inside the polymer powder to form a dense structure, it generally has better solvent resistance than the polymer powder prepared using a low specific gravity monomer. . In addition, when the foam space is formed in the two-layer structure it can be confirmed that the low specific gravity is easier to achieve than the polymer beads formed free volume in the molecular structure. The outermost layer can maintain a more stable solution state by minimizing the solvent resistance problem that can occur due to the foam space formation.

In more detail, the vinyl monomer having 2 or more carbon atoms used in forming the core layer has ethyl, butyl, or the like instead of the methyl group, and has a molecular structure free volume due to the long chain effect. ) Specific gravity of the monomer itself is lower than methyl methacrylate. However, when the free volume has a weakness in solvent resistance. Therefore, in order to compensate for this, it is important to effectively control the use and prescription of various crosslinking agents to maintain solvent resistance.

Such a low specific gravity large diameter polymer powder production method of the present invention

(A) Emulsion polymerization in the presence of a vinyl monomer having 2 or more carbon atoms and aryl methacrylate to form a core layer free of internal pores, and (B) polymerization in the presence of glycidyl methacrylate, methyl methacrylate and a blowing agent. To form a pore layer having pores on the outer surface of the core layer, and (C) polymerize in the presence of an acid monomer and methyl methacrylate to form a protective layer on the outer surface of the pore layer to form a core layer, a pore layer and a protective layer from the inside. It may comprise the step of preparing a polymer powder having a three-layer structure of.

At this time, the emulsion polymerization in the step (A) may proceed further comprising a polyfunctional monomer, a polymerization initiator and a suspension stabilizer.

In the step (B), the polymerization may further include a multifunctional monomer, a polymerization initiator, and a suspension stabilizer.

In the step (C), the polymerization may further include a multifunctional monomer, a polymerization initiator, and a suspension stabilizer.

Therefore, the manufacturing method of the polymer powder of this invention,

(A) emulsifying and polymerizing a first solution containing a vinyl monomer having 2 or more carbon atoms, aryl methacrylate, a polyfunctional monomer, a polymerization initiator and a suspension stabilizer, and then polymerizing to form a core layer having no internal voids;

(B) adding a second solution containing methyl methacrylate, glycidyl methacrylate, a polyfunctional monomer, a blowing agent, a polymerization initiator, and a suspension stabilizer to a polymerization reactor including a core layer having no internal voids and suspending polymerization; To form a pore layer having pores on the outer surface of the core layer,

(C) adding a third solution containing methyl methacrylate, an acid monomer, a polyfunctional monomer, a polymerization initiator, and a suspension stabilizer to the polymerization reactor including the pore layer and suspending polymerization to form a protective layer on the outer surface of the pore layer. To prepare a polymer powder having a three-layer structure of a core layer, a pore layer, and a protective layer.

During the emulsion polymerization in step (A), by mixing the first solution using a homogenizer (Homomixer), it can proceed after obtaining a homogenized emulsion. The emulsification conditions are not particularly limited, but may be a conventional method, but may be preferably performed for 5 to 60 minutes at a temperature of 10 to 30 ℃.

The present invention obtains droplets of the desired particle size distribution through the emulsification process, and then puts the emulsion into a four-necked reactor within 2 to 40 hours in consideration of the amount of the residual monomer in a nitrogen atmosphere and 50 to 90 ℃ The polymerization may proceed at a temperature of to form a core layer free of internal pores. At this time, the stirring rate should be maintained so that the polymer powder produced during the polymerization reaction does not sink. Preferably, the stirring speed may be performed at 100 to 300 rpm. In this invention, the said homogenization suspension polymerization method generally used can be used, The method is not specifically limited.

The vinyl monomer having 2 or more carbon atoms included in the first solution of step (A) may use one or more selected from the group consisting of alkyl methacrylate (a) acrylate having an alkyl group of C2 to C16. Preferably, the vinyl monomer having 2 or more carbon atoms is one or more selected from the group consisting of alkyl methacrylates having alkyl groups of C2 to C12, more preferably lauryl methacrylate or butyl methacrylate. Can be used. The vinyl monomer having 2 or more carbon atoms may be appropriately mixed and used according to the desired specific gravity and the degree of solvent resistance. The content of the vinyl monomer having 2 or more carbon atoms may be used in an amount of 10 to 90 parts by weight based on 100 parts by weight in total of the monomer-containing composition for forming a core layer. In this case, if the content is less than 10 parts by weight, the specific gravity value of the polyfunctional monomer is high, so that the specific gravity value of the polymerized polymer powder is increased. If the content is more than 90 parts by weight, solvent resistance is poor due to the long chain effect of the main chain.

Meanwhile, in the present invention, "100 parts by weight of the total amount of the monomer-containing composition for core layer formation" is 100% by weight of the components of the C2 or more vinyl monomer, aryl methacrylate, polyfunctional monomer, and polymerization initiator used in the first solution. It means the monomer containing mixture containing a part.

The aryl methacrylate is characterized in that it is used to maintain a compatible bond with the pore layer to be formed later. The content of the aryl methacrylate may be used in an amount of 5 to 30 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the total of the monomer-containing composition for forming a core layer. When the content of the aryl methacrylate is less than 5 parts by weight, a poor layer may not be formed due to a poor problem in forming a two-layer surrounding the core layer. When the content of the aryl methacrylate exceeds 30 parts by weight, the vinyl-based and polyfunctional monomer content There is a problem that property control restrictions occur due to the reduction.

The polyfunctional monomers include trimethylolmethane tetraacrylate, trimethylolmethane triacrylate, trimethylolbutane triacrylate, ethylene glycol dimethacrylate, and ethylene glycol dimethacrylate. At least one selected from the group consisting of divinyl benzene may be used. At this time, the content of the polyfunctional monomer is not particularly limited and can be appropriately adjusted and used in the whole composition.

In addition, the polymerization initiator may be selected from the group consisting of an azo initiator and a peroxide initiator. The azo initiator is a compound capable of initiating polymerization by pyrolysis in a useful phase, for example, 2,2-azobisisobutyronitrile, 4,4-azobis (4) -cyanopenta Nosane, 2,2-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) and the like can be used. The peroxide initiator may be a compound such as benzoyl peroxide, lauryl peroxide, octanoyl peroxide, dicumyl peroxide, or the like.

It is preferable to use the said polymerization initiator in the range of 1-5 weight part with respect to a total of 100 weight part of the monomer containing composition for core layer formation. At this time, if the content is less than 1 part by weight, there is a problem that an unreacted monomer is generated in excess, and if it exceeds 5 parts by weight, there is a problem of poor polymerization stability due to rapid exotherm.

The suspension stabilizer is selected from the group consisting of polyvinyl pyrrolidone, polyvinyl methyl ether, polyethyleneimine, polymethyl methacrylate acrylic acid copolymer, polyvinyl alcohol, vinyl acetate copolymer, ethyl cellulose and hydroxypropyl cellulose. One or more compounds can be used.

It is preferable to use the suspension stabilizer in 1-10 weight part with respect to a total of 100 weight part of the monomer containing composition for core layer formation. At this time, if the content is less than 1 part by weight, there is a problem that a large amount of polymerized aggregates are generated in the emulsion stability, and if it exceeds 10 parts by weight, it is difficult to remove the suspension stabilizer in the polymer powder cleaning process.

In addition, in step (B), using a second solution containing methyl methacrylate, glycidyl methacrylate, a polyfunctional monomer, a blowing agent, a polymerization initiator and a suspension stabilizer, pores in a shell form on the outer surface of the core layer. The void layer having can be formed.

The polymerization conditions in the step (B) is not particularly limited, but may be performed for 2 to 12 hours at a temperature of 50 ℃ to 90 ℃.

In addition, in the present invention, methyl methacrylate can be used in consideration of price and compatibility as a matrix for forming the pore of the polymer powder. The content of methyl methacrylate included in the second solution is not particularly limited, and may be appropriately adjusted as long as it can play a role of a matrix, for example, based on a total of 100 parts by weight of the monomer-containing composition for forming a pore layer. 50 to 80 parts by weight can be used.

Meanwhile, in the present invention, "100 parts by weight of the total amount of the monomer-containing composition for forming the pore layer" refers to the components of the methyl methacrylate, glycidyl methacrylate, polyfunctional monomer, foaming agent and polymerization initiator used in the second solution. It means a monomer-containing mixture comprising a total of 100 parts by weight.

The glycidyl methacrylate content included in the second solution may be used in an amount of 20 to 40 parts by weight based on a total of 100 parts by weight of the monomer-containing composition for forming a pore layer.

The blowing agent is preferably used in 20 to 50 parts by weight based on a total of 100 parts by weight of the monomer-containing composition for forming a pore layer. The blowing agent may be used by mixing one or two or more selected from a physical foaming agent and a chemical foaming agent. Preferred physical foaming agents may be used, such as hexane, dichloroethane, toluene, and chemical foaming agents, p-toluene sulfonyl hydrazide (TSH), benzene sulfonyl hydrazide (BSH, Benzensulfonyl) hydrazide) may be used.

Here, the multifunctional monomer, the polymerization initiator and the suspension stabilizer included in the second solution may be used in the component and content ranges used in the first solution of step (A), and the conditions are not particularly limited.

In addition, the present invention is a core layer by forming a protective layer on the outer surface of the pore layer by using a third solution containing methyl methacrylate, acid monomer, polyfunctional monomer, polymerization initiator and suspension stabilizer in the step (C) Polymer powder having a three-layer structure of a void layer and a protective layer can be produced.

The acid monomer included in the third solution is preferably used in an amount of 5 to 40 parts by weight based on 100 parts by weight of the total of the monomer-containing composition for forming a protective layer. If the content of the acid monomer is less than 5 parts by weight, there is a problem in that sufficient reaction cannot be expected when forming the outermost three layers (protective layer), and if it exceeds 40 parts by weight, there is a problem in that the dispersion stability of the polymerization solution is inhibited. Acrylic acid or methacrylic acid may be used as the acid monomer, and other acid monomers may cause compatibility problems, which is not preferable.

Meanwhile, in the present invention, "100 parts by weight of the total amount of the monomer-containing composition for forming a protective layer" includes 100 parts by weight of the total components of methyl methacrylate, an acid monomer, a polyfunctional monomer, and a polymerization initiator used in the third solution. A monomer containing mixture is meant.

In addition, in the present invention, methylmethacrylate may be used in consideration of price and compatibility as a matrix when forming a protective layer of polymer powder. The content of methyl methacrylate included in the third solution is also not particularly limited, and may be appropriately adjusted as long as it can play a role of a matrix, for example, 50 based on 100 parts by weight of the monomer-containing composition for forming a protective layer. To 80 parts by weight.

The multifunctional monomer, polymerization initiator and suspension stabilizer included in the third solution may be used as the component and content used in the first solution of step (A), and the conditions are not particularly limited.

The polymerization conditions in step (C) are not particularly limited, but may be performed for 2 hours to 12 hours at a temperature of 50 ℃ to 90 ℃.

On the other hand, the present invention can also be selected in two ways to control the specific gravity, firstly to adjust the low specific gravity monomer input at the time of forming the core layer (a), or secondly to adjust the content of the blowing agent at the time of forming the void layer (b) There is a way to achieve that. In addition, the present invention can be used in combination of the above two methods in the production of the core layer (a), if the purpose is to produce a low specific gravity polymer powder having a large particle size.

In another aspect, the present invention may further comprise the step of recovering the powder after preparing the polymer powder through the step (C). The recovery method may use a method well known to those skilled in the art. For example, the finally obtained polymer powder may be filtered, washed with water and an aqueous ethanol solution, and the filtrate is put in a vacuum oven and dried for one day to prepare a white odorless spherical polymer powder.

The present invention also provides a spherical polymer powder prepared by the above method, wherein the spherical polymer powder prepared by the present invention is free of internal pores containing a polymer of a vinyl monomer having at least 2 carbon atoms and an aryl methacrylate. A core layer, a pore layer having pores containing polymers of glycidyl methacrylate and methyl methacrylate formed in a shell form on the outside and surrounding the core layer, and formed on the outside surrounding the pore layer and the solvent And a protective layer containing a polymer of an acid monomer and methyl methacrylate, which delays the contact of the polymer. In addition, the polymer powder has a CV value (Coefficient of Variation, coefficient of variation) of 20% or less, preferably 17.5% or less, an average particle diameter of 2 to 200 ㎛, preferably 30 to 200 ㎛ range, Specific gravity is a low specific gravity polymer powder of 1.20 or less.

The spherical low specific gravity polymer powders prepared according to the present invention have a very low specific gravity, and thus have very high crude liquid stability and a low CV value, thereby exhibiting a uniform light diffusion effect. Due to its properties, it is particularly suitable for use as a material capable of controlling optical properties such as a diffusion film of a TFT-LCD, a light diffusing agent of a light diffusion plate, and an additive of various plastic moldings.

The polymer powder prepared according to the present invention has a very low specific gravity and at the same time has a very good surface condition, almost no impurities, and has a uniform sized spherical shape, which is excellent in physical properties such as optical properties, powder flowability, processability and strength. It is very suitable for use as light diffusing agents such as optical films and light diffusing plates, plastic moldings, additives of various films, and the like.

In addition, it is possible to effectively produce a large diameter low specific gravity multilayer polymer powder having a specific gravity of 1.2 or less, which is difficult to achieve in the past, and having a diameter of 100 μm or more, and improve the storage solution stability and stability.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited by the following examples.

Example 1

59 parts by weight of lauryl methacrylate (LMA) as a vinyl monomer, 20 parts by weight of ethylene glycol dimethacrylate (EGDMA) as a polyfunctional monomer, and 20 parts by weight of aryl methacrylate are mixed. 1 part by weight of 2'-azobis (2,4-dimethylvaleronitrile) (ADVN) was added. Then, 5 parts by weight of polyvinyl alcohol (PVA) as a suspension stabilizer was dissolved using ion water as a dispersion medium, and the mixture was administered to the solution, and homogenized at 8000 rpm for 5 minutes using a high speed stirrer to emulsify it. Thereafter, the emulsion was placed in a reaction tube and polymerized at 50 ° C. for 2 hours under a nitrogen atmosphere to form a core layer (a).

50 parts by weight of methyl methacrylate, 20 parts by weight of glycidyl methacrylate, 5 parts by weight of ethylene glycol dimethacrylate, 24 parts by weight of toluene, and 2,2'-azobis in the polymerization reactor in which the polymerization reaction is completed. 2 parts by weight of polyvinyl alcohol was added to 4,4-dimethylvaleronitrile) (ADVN) 1 and polymerization was performed at 50 ° C. for 4 hours under a nitrogen atmosphere to form a void layer (b).

Subsequently, in the polymerization reactor in which the polymerization reaction was completed, 30 parts by weight of methyl methacrylate, 50 parts by weight of methacrylic acid, 29 parts by weight of ethylene glycol dimethacrylate, and 2'-azobis (2,4-dimethylvaleronitrile) 1 part by weight of (ADVN) and 1.5 parts by weight of polyvinyl alcohol were added thereto, and the temperature was raised to 75 ° C. to proceed with polymerization for 4 hours to form a protective layer (c).

The polymer synthesized by the above reaction was filtered, washed with water and aqueous ethanol solution, and the filtrate was put in a vacuum oven and dried for one day to prepare a white odorless spherical polymer powder.

Example 2

In the step of forming the core layer (a), 69 parts by weight of lauryl methacrylate (LMA), 10 parts by weight of ethylene glycol dimethacrylate (EGDMA), and 20 parts by weight of aryl methacrylate are mixed, and polymerization starts here. A white odorless spherical polymer composite powder was prepared in the same manner as in Example 1, except that 1 part by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) (ADVN) was added. It was.

Example 3

In the step of forming the pore layer (b), 40 parts by weight of methyl methacrylate, 20 parts by weight of glycidyl methacrylate and 5 parts by weight of ethylene glycol dimethacrylate are used as the monomer mixture, and 34 parts by weight of toluene, 2, A white odorless spherical polymer composite powder was prepared in the same manner as in Example 1, except that 1 'part of 2'-azobis (2,4-dimethylvaleronitrile) (ADVN) was polymerized. .

Example 4

In order to produce a low specific gravity polymer powder having a large particle diameter, the amount of the low specific gravity monomer in the core layer production and the content of the blowing agent in the pore layer production were adjusted.

That is, in the step of forming the void layer (b), using a monomer mixture, 30 parts by weight of methyl methacrylate, 20 parts by weight of glycidyl methacrylate, 5 parts by weight of ethylene glycol dimethacrylate, and 44 parts by weight of toluene , 2,2'-azobis (2,4-dimethylvaleronitrile) (ADVN) except that the polymerization was carried out in the same manner as in Example 1, except that the white odorless spherical polymer composite powder Was prepared.

Comparative Example 1

79 parts by weight of methyl methacrylate (LMA) and 20 parts by weight of ethylene glycol dimethacrylate (EGDMA) are mixed, and 2,2'-azobis (2,4-dimethylvaleronitrile) (ADVN) is used as a polymerization initiator. ) 1 part by weight was added. Thereafter, homogenization conditions and polymerization reaction conditions were performed in the same manner as in Example 1 to prepare a polymer powder having a single layer structure.

Comparative Example 2

In the preparation of the core layer (a), 69 parts by weight of methyl methacrylate (LMA), 10 parts by weight of ethylene glycol dimethacrylate (EGDMA), and 20 parts by weight of aryl methacrylate are mixed, and as a polymerization initiator, 2 A white odorless spherical polymer composite powder was prepared in the same manner as in Example 1, except that 1 part by weight of 2'-azobis (2,4-dimethylvaleronitrile) (ADVN) was added.

Comparative Example 3

In the step of preparing the pore layer (b), 74 parts by weight of methyl methacrylate, 20 parts by weight of glycidyl methacrylate, and 5 parts by weight of ethylene glycol dimethacrylate are used as the monomer mixture, and 2,2'-azobis is used. A white odorless spherical polymer composite powder was prepared in the same manner as in Example 1, except that 1 part by weight of (2,4-dimethylvaleronitrile) (ADVN) was polymerized.

Experimental Example 1

[comparison analysis]

In order to compare the spherical polymer powders prepared in Examples 1-4 and Comparative Examples 1-2, SEM measurement, product yield measurement, average particle size, true specific gravity, etc. of each sample were measured. Table 1 shows.

SEM measurement: Hitachi S-4300

-Product yield measurement: yield calculation after filtration

Average particle size: Coulter Multisizer M3

-Specific gravity measurement: Pycnometer (Micromeritics instrument)

-Solvent resistance measurement: Viscosity is measured over time by mixing the same amount of solvent and polymer powder (Medium ethyl ketone (hereinafter referred to as MEK) after 12 hours of polymer powder is measured, the viscosity of the original viscosity up to 200% or less) Express)

TABLE 1

SEM Average particle size (㎛) Heavy weight Solvent resistance C.V. Product yield (%) Example 1 Good 50 1.18 Good 15.5 94.5 Example 2 Good 50 1.16 Good 16.2 95.0 Example 3 Good 50 1.14 Good 15.9 95.0 Example 4 Good 50 1.10 Good 17.2 94.2 Comparative Example 1 Good 50 1.36 Good 18.0 93.2 Comparative Example 2 Good 50 1.23 Good 18.8 93.2 Comparative Example 3 Good 50 1.26 Good 16.8 94.2

As shown in Table 1, the spherical polymer powder prepared in Examples 1 to 4 of the present invention has a low specific gravity value compared to Comparative Examples 1 to 3, but has an average particle size, surface state, and solvent resistance equal to or higher than these. And product yield, and the coefficient of variation was excellent. Particularly, in the case of Example 3 of the present invention, the specific gravity was reduced to 1.14 even if a small amount was added compared to the powder prepared using the methyl methacrylate of Comparative Example 1 as a main chain, and the effect was equal to or higher than that of the conventional polymer powder. Indicated. The polymer powder according to the present invention was normally polymerized without abnormal polymerization during the polymerization process, so that the product yield was also not significantly different from that of Comparative Example 1, and the average particle size was also the same.

On the other hand, the polymer powder of Comparative Examples 1 to 3, even if the physical property value is similar to the present application, the specific gravity value is higher than 1.2, when used as a light diffusing agent is excessively used.

At this time, the spherical polymer powder according to Example 1 of the present invention, it can be seen that 50um large diameter particles are produced in a good state as shown in the SEM results of FIG. In the case of the polymer powder of the three-layer structure of Example 1 of the present invention, as shown in Figs. 6A and 6B, voids were formed on the surfaces of the two layers (pore layers). In addition, in the case of the outermost protective layer of the polymer powder of the present invention, as shown in Fig. 7, it can be seen that the surface is smoothly formed on the pore layer.

Experimental Example 2

The polymer powders of Example 4 and Comparative Example 1 were used to compare the precipitation rates for each time change in the actual crude solution, and the results are shown in Table 2 (speed comparison unit:%).

In the measurement method, 10 g of the polymer powder was added to 30 g of the crude liquid MEK, dispersed, and left to stand to confirm sedimentation. The height of the transparent crude liquid layer except for the polymer powder precipitated layer was measured by time to confirm. At this time, the height change value of Comparative Example 1 was converted to 100% and compared with Example 4.

TABLE 2

1 hours 2 hours 4 hours 8 hours 12 hours 24 hours Example 4 100% 100% 100% 100% 100% 100% Comparative Example 1 60% 60% 60% 60% 60% 60% Improvement 40% 40% 40% 40% 40% 40%

In the case of Example 4 from the results of Table 2, the precipitation rate was greatly improved over time.

Experimental Example 3

After preparing the light-diffusion film preparation crude liquid by the conventional method using the polymer powder of Example 4 and the comparative example 1, the use amount of the beads in the crude liquid was compared.

[Table 3]

Bead use in crude liquid TT Luminance Luminance Relative luminance Comparative Example 1 22 wt% 59.5% 6706.4 Ref. Example 4 15 wt% 60.0% 6644.4 -0.92% week)
Ref .: Comparative Example 1
TT: Total Transmittance

From the results of Table 3, when using a material with a low specific gravity as in the present invention, the amount of the light diffusion film manufacturing crude liquid introduced on a weight basis can be reduced than that of Comparative Example 1, so that up to 40% based on the same optical properties finally It could be used after saving.

Therefore, the spherical multilayer polymer powders of Examples 1 to 4, which are economically prepared compared to the prior art, have a low specific gravity, which is excellent in crude liquid storage and stability, and can reduce the amount of use when prescribed on a weight basis, such as an optical film and a light diffusion plate. It can exhibit suitable physical properties for use as a light diffusing agent. That is, since the present invention exhibits a low specific gravity, even when a smaller amount is used than a conventionally used polymer powder when used as a light diffusing agent, the present invention may enjoy an effect equal to or higher than that of the conventional art. In addition, the spherical polymer powder of the present invention can be usefully used as various molding additives of plastics.

1 shows a schematic diagram of a polymer powder having a three-layer structure according to the present invention.

Figure 2 shows the process of forming a three-layer structure in the manufacturing process of the polymer powder according to the present invention.

Figure 3 shows the approximate concept in the preparation of the polymer powder according to the present invention.

Figure 4a shows the compound reacted in the process of forming a pore layer on the core layer during the polymer powder manufacturing process according to the present invention, Figure 4b shows the compound reacted in the process of forming a protective layer on the pore layer.

5 is an electron micrograph of the spherical polymer powder according to Example 1 of the present invention.

Figure 6a is an electron micrograph showing the surface of the two layers (porous layer) in the polymer powder of the three-layer structure of Example 1 according to the present invention, Figure 6b is an electron microscope picture showing an enlarged surface of the two layers. .

7 is an electron micrograph showing the surface of the outermost three layers (protective layer) in the polymer powder of the three-layer structure of Example 1 according to the present invention.

Claims (17)

A core layer having no internal voids containing a polymer of at least 2 vinyl monomers and aryl methacrylate, A pore layer surrounding the core layer and having pores containing polymers of glycidyl methacrylate and methyl methacrylate formed in a shell form on the outside, and A protective layer containing a polymer of an acid monomer and methyl methacrylate formed on the outside and delaying contact of the solvent surrounding the pore layer Spherical low specific gravity multilayer polymer powder comprising a. The spherical low specific gravity multilayer polymer powder according to claim 1, wherein the polymer powder has an average particle diameter of 30 to 200 µm and a true specific gravity value of 1.20 or less. (A) emulsion core polymerization in the presence of a vinyl monomer having 2 or more carbon atoms and aryl methacrylate to form a core layer having no internal voids, (B) polymerizing in the presence of glycidyl methacrylate, methyl methacrylate and a blowing agent to form a pore layer having pores on the outer surface of the core layer, (C) polymerizing in the presence of an acid monomer and methyl methacrylate to form a protective layer on the outer surface of the pore layer to prepare a polymer powder having a three-layer structure of a core layer, a pore layer, and a protective layer from the inside; , A method for producing a spherical low specific gravity multilayer polymer powder having an average particle diameter of 30 to 200 µm, a coefficient of variation (C.V value) of 20% or less, and a specific gravity of 1.20 or less. The method of claim 3, wherein the emulsion polymerization in the step (A) further comprises a polyfunctional monomer, a polymerization initiator and a suspension stabilizer. The vinyl monomer of claim 3, wherein 10 to 90 parts by weight based on a total of 100 parts by weight of the monomer-containing composition for forming a core layer comprising a C2 or more vinyl monomer, an aryl methacrylate, a polyfunctional monomer, and a polymerization initiator. The method of claim 3, wherein the vinyl monomer having 2 or more carbon atoms is selected from the group consisting of lauryl methacrylate and butyl methacrylate. The method of claim 3, wherein the aryl methacrylate is A method for producing a low specific gravity multilayer polymer powder, which is used in an amount of 5 to 30 parts by weight based on 100 parts by weight of the total amount of the monomer-containing composition for forming a core layer including C2 or more vinyl monomers, aryl methacrylates, polyfunctional monomers, and a polymerization initiator. . The method according to claim 3, wherein the polymerization in the step (B) further comprises a polyfunctional monomer, a polymerization initiator and a suspension stabilizer. The method of claim 3, wherein the glycidyl methacrylate is A method for producing a polymer powder, which is used in an amount of 20 to 40 parts by weight based on 100 parts by weight of a monomer-containing composition for forming a pore layer containing methyl methacrylate, glycidyl methacrylate, a polyfunctional monomer, a blowing agent, and a polymerization initiator. The method of claim 3, wherein the blowing agent A method for producing a polymer powder, which is used at 20 to 50 parts by weight based on 100 parts by weight of the total composition of the monomer-containing composition for forming a pore layer containing methyl methacrylate, glycidyl methacrylate, a polyfunctional monomer, a blowing agent and a polymerization initiator. . The method of claim 3, wherein the blowing agent is at least one selected from the group consisting of hexane, dichloroethane, toluene, p-toluene sulfonyl hydrazide, and benzene sulfonyl hydrazide. The method according to claim 3, wherein the polymerization in the step (C) further comprises a polyfunctional monomer, a polymerization initiator and a suspension stabilizer. The method of claim 3, wherein the acid monomer is A method for producing a polymer powder, which is used in an amount of 5 to 40 parts by weight based on 100 parts by weight of a total of a monomer-containing composition for forming a protective layer containing methyl methacrylate, an acid monomer, a polyfunctional monomer, and a polymerization initiator. The method for producing a polymer powder according to claim 3, wherein the acid monomer is acrylic acid or methacrylic acid. The method according to any one of claims 4, 8 and 12, The polyfunctional monomer is to use one or more selected from the group consisting of trimethylolmethane tetraacrylate, trimethylolmethane triacrylate, trimethylolbutane triacrylate, ethylene glycol dimethacrylate and divinylbenzene, Method for producing polymer powder. The method according to any one of claims 4, 8 and 12, The suspension stabilizer is selected from the group consisting of polyvinyl pyrrolidone, polyvinyl methyl ether, polyethyleneimine, polymethyl methacrylate acrylic acid copolymer, polyvinyl alcohol, vinyl acetate copolymer, ethyl cellulose and hydroxypropyl cellulose. A method for producing a polymer powder, which uses more than one species. The method according to any one of claims 4, 8 and 12, The polymerization initiator is selected from the group consisting of an azo initiator and a peroxide initiator, a method for producing a polymer powder.

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