JPH1088008A - Production of resin containing light diffusing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate homogeneous dispersion of fine resin particles in a transpart resin by melting and mixing fine resin particles with a dispersion aid and then melting and mixing this mixture with a transparent resin. SOLUTION: In producing a resin containing a light diffusing agent by incorporating a light diffusing agent comprising fine resin particles into a transparent resin, fine resin particles are melted and mixed with a dispersion aid, and the mixture is melted and mixed with a transparent resin. The resin particles used are those having a mean diameter of 0.1-50μm. The resin particles in this range are suitable for impartation of good light diffusivity. The resin particles having a mean particle diameter outside that range are not desirable. If the particle diameter is less than 0.1μm, the light diffusivity will be lowered since the particle diameter is close to the wavelength of light; if it is above 50μm, the light diffusivity will also be lowered. Truly spherical resin particles exhibit a desirable light diffusion effect. The resin particles preferably used are those of which the absolute value of difference in refractive index from a transparent resin is 0.02 to 0.2. If the value is less than 0.02, the light diffusivity will be low; if it is above 0.2, the light transmittance will be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a light-diffusing agent-containing resin in which resin fine particles as a light-diffusing agent are dispersed. More specifically, the present invention relates to a method for producing a light diffusing agent-containing resin in which fine resin particles are uniformly dispersed without crushing. The light diffusing agent-containing resin of the present invention is useful as a masterbatch suitable for dispersing resin fine particles in a transparent resin.

[0002]

2. Description of the Related Art In recent years, resin fine particles have been increasingly used instead of inorganic powders as light diffusing agents for transparent resins. When the inorganic powder is added to the transparent base resin, there is a disadvantage that the light transmittance is greatly reduced even though sufficient light diffusivity is obtained, and further, the physical properties of the transparent base resin such as impact strength are reduced. There was also a drawback.

When resin powders having different refractive indices, such as polystyrene and polymethyl methacrylate, are added to the transparent resin of the base material, the light diffusion effect is limited to some extent. To improve this, Japanese Patent Laid-Open Publication No.
No. 04 discloses polymer particles obtained by dispersing a polymerizable vinyl monomer and resin fine particles insoluble in the monomer in an aqueous system and performing suspension polymerization, and in which resin fine particles are dispersed.

On the other hand, in the case of a light guide plate or the like using resin fine particles as a light diffusing agent, the amount of resin fine particles in a molded article is 0.1.
It is about 01 to 0.1% by weight, which is very small. Therefore, it is common practice to prepare a masterbatch having a higher concentration than that in the molded body and use it to uniformly disperse the resin fine particles in the molded body resin.

[0005]

As a method of adding and mixing resin fine particles to a transparent resin, there is a method of mechanical kneading or a method of adding the resin fine particles during polymerization of the resin. However, there was a disadvantage that the particles were crushed and it was difficult to exhibit the original performance of the fine particles. Also, the method of adding at the time of polymerization is described in JP-A-4-337304.
It is disclosed that a polymerizable vinyl monomer and fine polymer particles insoluble in the monomer are dispersed in an aqueous system and obtained by suspension polymerization, as disclosed in the above publication. But,
Considering the equipment, it is hard to say that it is an economical method,
The polymer described has a molecular weight of about several hundred thousand to one million, is difficult to melt, and has poor compatibility with the molded resin.

In view of such circumstances, the present inventors have made intensive studies on a resin containing a light diffusing agent in which resin fine particles are easily dispersed uniformly in a transparent resin, and as a result, the resin fine particles are dispersed in advance. The present inventors have found that resin particles can be easily and uniformly dispersed in a transparent resin by melt-mixing with a transparent resin after being melt-mixed with an auxiliary agent, thereby completing the present invention.

[0007]

That is, the present invention relates to a method for producing a resin containing a light diffusing agent by mixing resin fine particles as a light diffusing agent in a transparent resin. And then melt-mixing the resulting mixture with a transparent resin.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The transparent resin in the present invention is not particularly limited as long as it is transparent. Examples thereof include a methacrylic resin, a styrene resin, and a carbonate resin, and a methacrylic resin is preferably used.

The MFR (JIS K721) of this transparent resin
0) is preferably 1 to 50 (g / 10 minutes). 1 (g / 1
0 minutes), the compatibility with the molded resin is inferior.
If it is larger than (g / 10 minutes), the mechanical strength and heat resistance are inferior, which is not preferable.

The methacrylic resin is a homopolymer of methyl methacrylate or a copolymer of 50% or more of methyl methacrylate and another vinyl monomer. Examples of the vinyl monomer to be copolymerized with methyl methacrylate include, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate. Methacrylates such as methyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc .; methacrylic acid, Unsaturated acids such as acrylic acid; styrene,
α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like. The copolymer may further contain an elastomer component such as polybutadiene, butadiene / butyl acrylate copolymer, or polybutyl acrylate copolymer, and a glutaric anhydride unit or a glutarimide unit.

The resin fine particles used in the present invention include:
The absolute value of the difference between the refractive index and the refractive index of the transparent resin is 0.0
Those of 2 to 0.2 are preferably used. If it is less than 0.02, the light diffusivity is low, and if it is more than 0.2, the light transmittance is low. Specific examples of the resin fine particles used in the present invention include crosslinked siloxane-based resin fine particles, crosslinked styrene-based resin fine particles, crosslinked methyl methacrylate-based resin fine particles, and inorganic powder-containing crosslinked methyl methacrylate-based resin fine particles. .

The average particle system of the resin fine particles is 0.1 to 50 μm.
m, preferably 1.5 to 10 μm.
Resin fine particles in this range are suitable for imparting good light diffusing properties. If the particle diameter is less than 0.1 μm, the particle diameter is closer to the wavelength of light, so that the light diffusibility is reduced. The fine resin particles exhibit a preferable light diffusion effect when they are spherical.

The fine particles of crosslinked siloxane resin are generally called silicone rubber or silicone resin, and are solid at room temperature. The siloxane-based resin is mainly produced by hydrolysis and condensation of chlorosilane. For example, a siloxane-based resin can be obtained by condensing chlorosilanes represented by dimethyldichlorosilane, diphenyldichlorosilane, phenylmethylchlorosilane, methyltrichlorosilane, and phenyltrichlorosilane with hydrolysis. Furthermore, these siloxane-based resins are converted to benzoyl peroxide, -2,4-peroxide.
Dichlorobenzoyl, -p-chlorobenzoyl peroxide,
Cross-linking with a peroxide such as dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, or introduction of a silanol group at the end of a siloxane resin Then, a crosslinked siloxane-based resin is produced by condensation crosslinking with alkoxysilanes. In particular, two organic groups per silicon atom
A crosslinked siloxane-based resin in which up to three are bonded is preferred.

To obtain crosslinked siloxane-based resin fine particles,
A method of mechanically pulverizing the crosslinked resin,
68333 and JP-A-60-13813 can be used. Commercially available products include "Tospearl Series" manufactured by Toshiba Silicone Co., Ltd., "Trefill Series" manufactured by Toray Dow Corning Silicone Co., Ltd., and "Silicone Powder" manufactured by Shin-Etsu Chemical Co., Ltd.

The crosslinked styrene resin is a monomer containing 50% by weight or more of a styrene monomer unit, and a monomer having one radically polymerizable double bond in the molecule.
It is a resin obtained by polymerizing 0.1 to 50% by weight of a monomer having at least 2 radical-polymerizable double bonds in the molecule, at most 9% by weight. Styrene-based monomers are styrene and its derivatives. Examples of the styrene derivative include, but are not limited to, halogenated styrenes such as chlorostyrene and bromostyrene, and alkyl-substituted styrenes such as vinyltoluene and α-methylstyrene. Further, two or more styrene monomers may be used in combination.

A double bond capable of radical polymerization is contained in the molecule.
There is no particular limitation on the monomer having the number of monomers as long as it copolymerizes with the styrene-based monomer. For example, methyl (meth) acrylate, ethyl (meth) acrylate,
Alkyl (meth) acrylates such as propyl (meth) acrylate; and acrylonitrile. Of these, alkyl methacrylates such as methyl methacrylate are particularly preferred. Incidentally, two or more monomers may be used in combination.

The monomer having at least two radical polymerizable double bonds in the molecule is, for example, an alkyl such as 1,4-butanediol di (meth) acrylate and neopentyl glycol di (meth) acrylate. Diol di (meth) acrylates, such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and tetrapropylene glycol di (meth) acrylate Alkylene glycol di (meth) acrylates; aromatic polyfunctional compounds such as divinylbenzene and diallyl phthalate; trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate (Meth) acrylates of polyhydric alcohols such as and the like. Two or more of these monomers may be used in combination.

These constituents can be polymerized by known methods such as suspension polymerization, microsuspension polymerization, emulsion polymerization, and dispersion polymerization, and classified if necessary to obtain fine particles having a desired particle size. it can.

The light-diffusing agent-containing methyl methacrylate-based resin in which the resin fine particles are dispersed is obtained by heating and melting the methyl methacrylate-based resin, and adding and mixing the resin fine particles into the molten state, thereby crushing the resin fine particles. A resin dispersed uniformly can be obtained without performing the above. For example,
It can be easily manufactured using a Brabender plast mill, a kneader, a Banbury mixer, a roll, a single-screw extruder, or an extruder having a structure in which resin fine particles can be added to the melting zone of the resin in the middle by a twin-screw extruder.

As the dispersing aid used in the present invention, fatty acid esters and fatty acid amides are used. As the fatty acid esters, for example, methyl, ethyl, propyl, butyl esters of lauric acid, methyl, ethyl, propyl, butyl esters of palmitic acid, methyl, ethyl, propyl, butyl esters of stearic acid, Oleic acid methyl, ethyl, propyl, butyl esters, behenic acid methyl, ethyl, propyl,
Examples thereof include esters of butyl and behenyl, myristyl myristate, stearyl stearate, monoglyceride laurate, monoglyceride palmitate, monoglyceride stearate, monoglyceride oleate, monoglyceride behenate and the like. Fatty acid amides include lauric acid amide, stearic acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, behenic acid amide, erucic acid amide, methylenebisoleic acid amide, methylenebisstearic acid amide, methylenebisbehenic acid Examples thereof include amide amide, ethylene bisoleic acid amide, ethylene bis oleic acid amide, ethylene bis stearic acid amide, hexamethylene bis erucic acid amide, hexamethylene oleic acid amide, and hexamethylene stearic acid amide. These can be used alone or in combination of two or more.

The mixing ratio of the fine resin particles and the dispersing agent may be any ratio as long as the fine resin particles are sufficiently mixed when the dispersing agent is heated and the fine resin particles are added and mixed, but the mixing ratio is preferably as small as possible. If the amount is too large, a large amount of the dispersing aid will enter into the molded article, which adversely affects heat resistance, weather resistance and the like, which is not preferable.

First, the dispersant is heated and melted, and resin fine particles as a light diffusing agent are added and mixed to disperse well, then taken out, cooled, and pulverized. Next, the molten mixture of the dispersant and the resin fine particles is melt-mixed with a transparent resin. This melt-mixing method is not only a method using a kneading apparatus such as a commonly used single-screw or twin-screw extruder, various kinds of kneaders, but also a method of directly kneading during a melt processing operation such as injection molding or extrusion molding. There is. A mixture of the molten mixture and the transparent resin may be melted, or a molten mixture of a dispersant and resin fine particles may be added to and mixed with the transparent resin in a molten state.

The light-diffusing agent-containing resin of the present invention includes a known antioxidant such as a hindered phenol-based antioxidant, a phosphorus-based antioxidant and a sulfur-based antioxidant, an ultraviolet absorber, and a hindered amine-based light. A weathering agent such as a stabilizer may be added.

[0024]

According to the method of the present invention, resin fine particles as a light diffusing agent can be uniformly dispersed in a transparent resin without being crushed. It is suitably used as a master batch for the production of

[0025]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 Silicone resin fine particles (Tospearl 1) were used as resin fine particles.
45: Toshiba Silicone Co., Ltd., average particle size 4.5μ
m) 50 parts by weight and 50 parts by weight of stearic acid monoglyceride were melt-mixed in a separable flask at 80 ° C., cooled, and coarsened (MB1). Methacrylic resin (Sumipex MG5: Sumitomo Chemical Co., Ltd.) as a transparent resin
100 parts by weight) and 1.5 parts by weight of the above MB1 (the amount of the resin fine particles with respect to the transparent resin is 0.75% by weight) mixed with a super mixer, and then pelletized using a vent-type extruder having a screw diameter of 40 mm. To obtain a transparent resin in which resin fine particles are dispersed. When the dispersion state of the resin fine particles dispersed in the resin was observed with an optical microscope, the resin fine particles were uniformly dispersed without being crushed.

Example 2 Except for using polystyrene crosslinked fine particles (Fine Pearl: manufactured by Sumitomo Chemical Co., Ltd., average particle diameter 6.0 μm) instead of silicone resin fine particles as resin fine particles,
In the same manner as in Example 1, a transparent resin in which resin fine particles were dispersed was obtained. When the dispersion state of the resin fine particles dispersed in the resin was observed with an optical microscope, the resin fine particles were uniformly dispersed without being crushed.

Comparative Example 1 A methacrylic resin (Sumipex MG) was used as a transparent resin.
5: 100 parts by weight of Sumitomo Chemical Co., Ltd.) 100 parts by weight of silicone resin fine particles as resin fine particles (Tospearl 145: Toshiba Silicone Co., Ltd., average particle diameter 4.5 μm) 0.7
After mixing 5 parts by weight with a super mixer, the mixture was pelletized in the same manner as in Example 1 to obtain a transparent resin in which resin fine particles were dispersed. When the dispersion state of the resin fine particles dispersed in the resin was observed with an optical microscope, a large number of crushed resin fine particles were observed.

Claims (7)

[Claims] 1. A method for producing a light-diffusing agent-containing resin by mixing resin fine particles as a light-diffusing agent in a transparent resin,
A method for producing a light-diffusing agent-containing resin, which comprises melt-mixing resin fine particles and a dispersing agent in advance, and then melt-mixing the resulting mixture with a transparent resin. 2. The resin fine particles have an average particle size of 0.1 to 50.
The production method according to claim 1, wherein the thickness is μm. 3. The transparent resin having an MFR of 1 to 50 (g / 10
2. The production method according to claim 1, wherein 4. The method according to claim 1, wherein the transparent resin is a methyl methacrylate resin. 5. The method according to claim 1, wherein the resin fine particles are silicone resin fine particles or polystyrene crosslinked fine particles. 6. The amount of fine resin particles in the transparent resin is from 0.1 to 0.1.
The method according to claim 1, wherein the amount is 1% by weight. 7. The method according to claim 1, wherein the dispersing aid is a fatty acid ester or a fatty acid amide.