JP4063901B2 - Manufacturing method of resin containing light diffusing agent - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a light diffusing agent-containing resin in which resin fine particles are dispersed. Specifically, the present invention relates to a method for producing a light diffusing agent-containing resin in which resin fine particles are uniformly dispersed without being crushed.
The light diffusing agent-containing resin of the present invention is useful as a master batch suitable for dispersing resin fine particles in a transparent resin.
[0002]
[Prior art]
In recent years, resin fine particles are increasingly used as light diffusing agents for transparent resins in place of inorganic powders. When an inorganic powder is added to a base transparent resin, there is a drawback that even if sufficient light diffusibility is obtained, the light transmittance is greatly reduced, and the physical properties of the base transparent resin such as impact strength are reduced. Also had the disadvantage of.
[0003]
Further, when a resin powder having a different refractive index, such as polystyrene or polymethyl methacrylate, is added to the base transparent resin, the light diffusion effect is limited to some extent. For the purpose of improving this, JP-A-4-337304 describes a polymerizable vinyl monomer and resin particles insoluble in the monomer dispersed in an aqueous system and obtained by suspension polymerization. Combined particles are disclosed.
[0004]
On the other hand, in the case of a light guide plate using resin fine particles as a light diffusing agent, the amount of resin fine particles in the molded body is about 0.01 to 0.1% by weight, which is very small.
Therefore, it is common to make a master batch having a higher concentration than that in the molded body and to uniformly disperse the resin fine particles in the molded body resin using the master batch.
[0005]
[Problems to be solved by the invention]
As a method of adding and mixing resin fine particles to a transparent resin, there are a method of mechanically mixing resin fine particles and a transparent resin and kneading them or a method of adding at the time of polymerization of the resin. The resulting fine particles were crushed and the original performance of the fine particles was difficult to express.
In addition, as disclosed in JP-A-4-337304, a method of adding at the time of polymerization can be obtained by suspension polymerization by dispersing a polymerizable vinyl monomer and fine polymer particles insoluble in the monomer in an aqueous system. It is shown. However, considering the equipment, it is difficult to say that it is an economical method, and the described polymer has a molecular weight of about several hundred thousand to one million, is difficult to melt, and is compatible with the molded body resin. Not good.
[0006]
In view of such circumstances, the present inventor has intensively studied a method for uniformly dispersing resin fine particles in a transparent resin without crushing. As a result, resin fine particles are added and mixed in a heated and melted transparent resin. As a result, the present invention has been completed.
[0007]
[Means for Solving the Problems]
That is, the present invention relates to a method for producing a light diffusing agent-containing resin by mixing resin fine particles, which are a light diffusing agent, with a transparent resin, heating and melting the transparent resin, and adding and mixing the resin fine particles to the transparent resin in a molten state. A method for producing a light diffusing agent-containing resin.
[0008]
DETAILED DESCRIPTION OF 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, and examples thereof include methacrylic resins, styrene resins, carbonate resins, and methacrylic resins are preferably used.
[0009]
The MFR (JIS K7210) of this transparent resin is preferably 1 to 50 (g / 10 minutes). If it is smaller than 1 (g / 10 minutes), the compatibility with the molded body resin is poor, and if it is larger than 50 (g / 10 minutes), the mechanical strength and heat resistance are inferior.
[0010]
A methacrylic resin is a copolymer of 50% or more of methyl methacrylate homopolymer or methyl methacrylate and another vinyl monomer.
Examples of the vinyl monomer copolymerized with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate. Methacrylates such as methyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and the like; 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, polybutyl acrylate copolymer, glutaric anhydride unit, or glutarimide unit.
[0011]
As the resin fine particles used in the present invention, those having an absolute value of the difference between the refractive index and the refractive index of the transparent resin of 0.02 to 0.2 are preferably used. When it becomes smaller than 0.02, the light diffusibility becomes low, and when it becomes larger than 0.2, the light transmittance decreases.
Specific examples of the resin fine particles used in the present invention include cross-linked siloxane-based resin fine particles, cross-linked styrene-based resin fine particles, cross-linked methyl methacrylate-based resin fine particles, and inorganic powder-containing cross-linked methyl methacrylate-based resin fine particles. .
[0012]
A resin fine particle having an average particle size of 0.1 to 50 μm, preferably 1.5 to 10 μm is used. This range of resin fine particles is suitable for imparting good light diffusibility.
If the particle diameter is less than 0.1 μm, the light diffusibility is lowered because the particle diameter is closer to the wavelength of light, and if it exceeds 50 μm, the light diffusibility is lowered.
The resin fine particles are preferably spherical and exhibit a preferable light diffusion effect.
[0013]
The crosslinked siloxane-based resin fine particles are generally called silicone rubber or silicone resin, and are solid at room temperature.
Siloxane resins are produced mainly by hydrolysis and condensation of chlorosilanes. For example, a siloxane-based resin can be obtained by condensing chlorosilanes represented by dimethyldichlorosilane, diphenyldichlorosilane, phenylmethylchlorosilane, methyltrichlorosilane, and phenyltrichlorosilane with hydrolysis.
Further, these siloxane-based resins are converted to benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2, A crosslinked siloxane-based resin is produced by crosslinking with a peroxide such as 5-di (t-butylperoxy) hexane, or by introducing a silanol group at the end of the siloxane resin and condensation-crosslinking with an alkoxysilane. The
Among these, a crosslinked siloxane-based resin in which 2 to 3 organic groups are bonded per silicon atom is preferable.
[0014]
In order to obtain the crosslinked siloxane-based resin fine particles, a method of mechanically pulverizing the crosslinked resin, a method described in JP-A-59-68333, JP-A-60-13813, or the like 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.
[0015]
Cross-linked styrene resin means 50% by weight or more of styrenic monomer units and, in addition, 49.9% by weight or less of monomers having one radical-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 two possible double bonds in the molecule.
Styrene monomers are styrene and its derivatives. Examples of the styrene derivative include, but are not limited to, halogenated styrene such as chlorostyrene and bromostyrene, alkyl-substituted styrene such as vinyltoluene, and α-methylstyrene.
Two or more of the above styrene monomers may be used in combination.
[0016]
The monomer having one double bond capable of radical polymerization in the molecule is not particularly limited as long as it is copolymerizable with the above-mentioned styrenic monomer. For example, methyl (meth) acrylate, ethyl Examples include alkyl (meth) acrylates such as (meth) acrylate and propyl (meth) acrylate; acrylonitrile and the like.
Of these, alkyl methacrylates such as methyl methacrylate are particularly preferred.
Two or more types of monomers may be used in combination.
[0017]
Monomers having at least two radically polymerizable double bonds in the molecule include alkyl diol di (such as 1,4-butanediol di (meth) acrylate and neopentyl glycol di (meth) acrylate). Meth) acrylates; alkylene glycols such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate Di (meth) acrylates; aromatic polyfunctional compounds such as divinylbenzene and diallyl phthalate; polyvalent compounds such as trimethylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate (Meth) acrylates of alcohols are exemplified.
Two or more of these monomers may be used in combination.
[0018]
These components can be polymerized by a known suspension polymerization method, micro suspension polymerization method, emulsion polymerization method, dispersion polymerization method or the like, and classified as necessary to obtain fine particles having a desired particle size.
[0019]
The light diffusing agent-containing resin in which the resin fine particles are dispersed is obtained by heating and melting the transparent resin, adding the resin fine particles to the molten state, and mixing them, thereby uniformly dispersing the resin fine particles without crushing them. Obtainable.
For example, it can be easily produced using an extruder having a structure in which resin fine particles can be added to the resin melting zone by a Brabender plast mill, a kneader, a Banbury mixer, a roll, a single screw extruder, or a twin screw extruder. .
[0020]
Moreover, at the time of well-known block polymerization, it can manufacture by adding a resin fine particle to the resin part in a molten state using the devolatilization extruder which provided the feed port at the devolatilization extruder front-end | tip.
[0021]
In addition, weathering agents such as hindered phenolic antioxidants, phosphoric acid antioxidants, sulfur antioxidants, UV absorbers and hindered amine light stabilizers are added as necessary and contained in the resin. You can also.
[0022]
【The invention's effect】
By the method of the present invention, resin fine particles that are light diffusing agents can be uniformly dispersed in the transparent resin without being crushed, and the obtained light diffusing agent-containing resin is a master for producing a light diffusing agent-containing molded article. It is suitably used as a batch.
[0023]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.
[0024]
Example 1
A twin-screw extruder (TEX30: manufactured by Nippon Steel Works, with 3 vents) was used as the melt kneader, and among the 3 vents of the extruder, the second feed weight feeder (KCL24-KT20) was used. : Manufactured by k-tron) and used as a feed port for addition of resin fine particles.
Extruder using Sumipex MG5 (manufactured by Sumitomo Chemical Co., Ltd.) as the methyl methacrylate resin and cross-linked siloxane resin fine particles (Tospearl 145: Toshiba Silicone Co., Ltd., average particle size 4.5 μm) as the resin fine particles. At a rotational speed of 250 rpm and an extruder set temperature of 220 ° C., 75 g / Hr of a crosslinked siloxane resin was added to and mixed with 15 kg / Hr of a methyl methacrylate resin to produce a light diffusing agent-containing resin.
When the resin fine particles dispersed in the resin were observed with an optical microscope, the resin fine particles were uniformly dispersed without crushing.
[0025]
Example 2
A light diffusing agent in the same manner as in Example 1 except that a crosslinked styrene resin fine particle (Fine Pearl: manufactured by Sumitomo Chemical Co., Ltd., average particle diameter 6.0 μm) was used as the resin fine particle instead of the crosslinked siloxane resin. A containing resin was produced.
When the resin fine particles dispersed in the resin were observed with an optical microscope, the resin fine particles were uniformly dispersed without crushing.
[0026]
Example 3
During bulk polymerization, using a devolatilizing extruder provided with a feed port at the tip of the devolatilizing extruder, resin fine particles were added to a methyl methacrylate resin in a molten state to produce a light diffusing agent-containing resin.
Methyl methacrylate (hereinafter referred to as MMA) 98.8% by weight, methyl acrylate (hereinafter referred to as MA) 1.0% by weight, n-octyl mercaptan (hereinafter referred to as OM) 0.2% by weight as a chain transfer agent In addition, a monomer solution composed of azobisisobutyronitrile (hereinafter referred to as AIBN) as a radical initiator was supplied to a polymerization reactor at 30 kg / Hr, and polymerization was performed at a temperature of 160 ° C.
[0027]
The obtained liquid polymer composition was taken out from the polymerization reactor, led to a heater, the liquid polymer composition was heated to 200 ° C., and then led to a devolatilizing extruder.
The devolatilizing extruder is a twin screw extruder (TEX30) manufactured by Nippon Steel, Ltd., and a weight feeder (KCL24-KT20: manufactured by K-tron) is attached to the vent port at the tip of the three for vents. Cross-linked siloxane resin fine particles (Tospearl 145: manufactured by Toshiba Silicone Co., Ltd., average particle size: 4.5 μm) were supplied at 75 g / Hr.
The methyl methacrylate resin and the crosslinked siloxane resin fine particles are extruded in a strand form from a die (rotation speed: 250 rpm, temperature: 250 ° C.), and after cooling with water, the light diffusing agent-containing resin is obtained as pellets at an average of 13.7 kg / Hr. It was.
When the resin fine particles dispersed in the resin were observed with an optical microscope, the resin fine particles were uniformly dispersed without crushing.
[0028]
Comparative Example 1
Supermixer 15 mg of Sumipex MG5 (manufactured by Sumitomo Chemical Co., Ltd.) as methyl methacrylate resin and 75 g of crosslinked siloxane resin fine particles (Tospearl 145: Toshiba Silicone Co., Ltd., average particle diameter 4.5 μm) as resin fine particles The mixture was stirred and mixed, supplied to the same twin-screw extruder as in Example 1 at 15 kg / Hr, and melted to obtain a light diffusing agent-containing resin.
When the resin fine particles dispersed in the resin were observed with an optical microscope, a large number of crushed resin fine particles were dispersed, and considerable dispersion failure was observed.

Claims (5)

In a method for producing a light diffusing agent-containing resin by mixing resin fine particles as a light diffusing agent in a transparent resin, the transparent resin is heated and melted, and the cross-linked siloxane resin fine particles and cross-linked styrene resin are added to the transparent resin in the molten state. A method of producing a light diffusing agent-containing resin comprising adding and mixing resin fine particles selected from fine particles (however, the resin fine particles are selected from the group consisting of phosphor-containing resin particles and fluorescent dye-containing resin particles) Except for the case of at least one fluorescent particle) .   The manufacturing method of Claim 1 whose MFR of transparent resin is 1-50 (g / 10min).   The method according to claim 1 or 2, wherein the transparent resin is a methacrylic resin.   The process according to claim 1, wherein the resin fine particles have an average particle size of 0.1 to 50 µm.   The process according to claim 1, wherein the amount of the resin fine particles relative to the transparent resin is 0.1 to 1% by weight.