JPH1160966A - Light diffusing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of manifesting high diffusion performances and a high light transmittance by dispersing two kinds of silicone resin fine particles having a particle diameter within a specific range in a transparent synthetic resin. SOLUTION: This composition is obtained by respectively dispersing (B) cross-linked resin fine particles having <5 μm average particle diameter in an amount of <=5 pts.wt. and (C) cross-linked resin fine particles having 5-10 μm average particle diameter in an amount of <=5 pts.wt. in (A) 100 pts.wt. transparent resin (preferably a methacrylic resin or the like). Silicone resin fine particles and/or styrene-based cross-linked resin fine particles are preferred as the cross-linked resin fine particles. An inorganic transparent substance powder in an amount of <=5 pts.wt. based on 100 pts.wt. component A can be mixed and dispersed in the composition. Thereby, the objective composition capable of expecting the utilization as a molding material such as an illumination cover, an illumination signboard, a display or a glazing is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing resin composition, and more particularly to a light diffusing resin composition suitable for lighting covers, lighting signs, displays, glazings and the like.

[0002]

2. Description of the Related Art Light-diffusing synthetic resins are used for lighting fixtures, various displays and the like, or as molding materials thereof. The properties required for light-diffusing synthetic resins include high light-diffusing properties. At the same time, it is increasingly required to have high light transmittance in terms of efficient use of electric energy. As such a light diffusing synthetic resin, for example, (a) a transparent synthetic resin containing an inorganic fine powder such as barium sulfate or calcium carbonate having an average particle diameter of 10 μm or less (Japanese Patent Application Laid-Open No. 60-1397)
No. 58), (b) Inorganic transparent substance powders such as glass powder, quartz powder and calcium fluoride powder having an average particle diameter of 1 to 10 μm, or 1 to 10 μm of polystyrene, polymethacrylate, and fluorinated acrylate organic. Transparent substance powder dispersed in transparent resin (Japanese Patent Publication Sho 60
Japanese Patent Application Laid-Open No. Sho 60-139758), (c) transparent fine particles such as silica, glass, calcium fluoride, and aluminum hydroxide having an average particle size of 4 to 50 μm dispersed in a transparent resin. JP-A-60-1845
No. 59, JP-A-61-4762), (d) those containing styrene-based crosslinked polymer fine particles having an average particle size of 0.5 to 5 μm (JP-B-39-10515).
A styrene resin or a crosslinked styrene-alkyl acrylate polymer having a particle diameter of 30 to 500 μm mixed and dispersed in an acrylic resin (JP-A-56-3653).
No. 5, JP-A-61-15940), and a crosslinked styrene-based polymer having an average particle diameter of 1 to 30 μm.
(E) Silicone fine particles having an average particle size of 1 to 6 μm and an inorganic transparent substance powder having an average particle size of 1 to 7 μm are dispersed (Patent Document 1). No. 251544).

[0003]

However, in the cases (a) to (c), since the inorganic substance powder is mainly added as the light diffusing fine particles, the purpose is to increase the total light transmittance. If the addition amount of the powder is reduced, the haze value (haze value) decreases and the internal lighting becomes transparent, while if the addition amount is increased so as not to be transparent, the total light transmittance decreases. There was a problem that would. In these cases, there are also problems such as the occurrence of wear damage to equipment and the like due to the hardness of the inorganic powder used, and the occurrence of defects such as die lines at the time of manufacturing an extruded plate. In the above (d) to (e), when crosslinked resin fine particles such as styrene-based crosslinked resin fine particles or silicone resin fine particles having a small particle diameter are used, the light diffusion property is superior to that of inorganic substance powder or the like, and the equipment is difficult to use. Although the problems are solved, the amount of addition must be increased to prevent the internal light source from being transparent, and it is not easy to achieve both higher light transmittance and concealment in response to market demands. On the other hand, when a crosslinked resin fine particle having a large particle diameter is used, a high light transmittance can be realized, but it is not easy to obtain more favorable light diffusion performance and concealment in response to market requirements. there were. Under such circumstances, it has been a reality that it is difficult to sufficiently respond to market needs that require a light-diffusing synthetic resin having a higher light-diffusing property and a higher light transmittance. Accordingly, an object of the present invention is to provide a light-diffusing synthetic resin having excellent light-diffusing property and high light transmittance, which is excellent in productivity.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that two types of silicone resin fine particles having a specific range of particle diameter or styrene-based crosslinked resin fine particles can be used as transparent synthetic resin. It has been found that by dispersing it in the medium, it is possible to express unprecedentedly high diffusion performance and high light transmittance, and thus have completed the present invention. That is, according to the present invention, the object is to provide a crosslinked resin fine particle having an average particle diameter of less than 5 μm in an amount of 5 parts by weight or less and an average particle diameter of 5 to 10 parts by weight in 100 parts by weight of a transparent resin.
a light-diffusing resin composition obtained by dispersing crosslinked resin fine particles of 5 μm in an amount of 5 parts by weight or less;
0 parts by weight, 5 parts by weight or less of crosslinked resin fine particles having an average particle diameter of less than 5 μm, 5 parts by weight or less of crosslinked resin fine particles having an average particle diameter of 5 to 10 μm, and 5 parts by weight of inorganic transparent material powder.
This can be achieved by a light diffusing resin composition which is dispersed in an amount of not more than part by weight.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.

[0006] The resin used in the present invention is not particularly limited as long as it has transparency, and examples thereof include methacrylic resins, styrene resins, and polycarbonate resins. Among these resins, a methacrylic resin containing methyl methacrylate having high light transmittance as a main component is preferably used.

The crosslinked resin particles used in the present invention include:
When polymerizing by adding to the monomer constituting the resin,
The resin is not particularly limited as long as it can maintain the particle shape when melt-mixed in the resin, and examples thereof include silicone resin fine particles, styrene crosslinked resin fine particles, acrylic crosslinked resin fine particles, and a core / shell having a rubber elastic layer. And fine resin particles. Among these resin fine particles, it is preferable to use silicone resin fine particles, styrene-based crosslinked resin fine particles, or an equivalent mixture of these two types of resin fine particles from the viewpoint of light diffusibility.

Examples of the above silicone resin fine particles include:
Silicone resin microparticles such as polymethylsilsesquioxane composed of trifunctional units manufactured by building-up process, which form dense siloxane bonds, are insoluble in solvents and are not soluble in heat. No. It is preferable that the shape of the light source be a true sphere rather than an amorphous shape because the haze value becomes higher and a so-called “transparency” phenomenon in which the shape of the light source can be seen through hardly occurs.

Examples of the styrene-based crosslinked resin fine particles include fine particles obtained by suspension-polymerizing a styrene-based monomer, a crosslinkable monomer and, if necessary, other monomers. It is preferable that the styrene-based crosslinked resin fine particles hardly dissolve even when mixed with a transparent resin and melt-extruded, and retain the original spherical shape. Also,
In order to improve the weather resistance of the styrene-based crosslinked resin fine particles,
Benzotriazole, hindered amine,
A light stabilizer such as a benzophenone type or a salicylic acid ester type may be added.

As the styrene monomer, styrene, α-methylstyrene, halogenated styrene and the like can be usually used, but styrene is preferably used. The amount of the styrene monomer used is usually in the range of 50 to 99% by weight, preferably 80 to 95% by weight. Also,
As the crosslinkable monomer, a compound having two or more unsaturated bonds in a molecule is used, and specific examples thereof include bifunctional compounds such as ethylene glycol dimethacrylate, 1,4-butanediol methacrylate, and neopentyl glycol. Dimethacrylate; polyvalent vinyl benzene such as divinyl benzene and the like can be preferably mentioned. The amount of the crosslinkable monomer used is usually in the range of 1 to 50% by weight, preferably 5 to 20% by weight. The other monomer used as necessary is not particularly limited as long as it can be polymerized with a styrene-based monomer and a crosslinkable monomer, and the amount of use thereof is also within a range that does not interfere with the object of the present invention. No problem.

The light-diffusing resin composition of the present invention contains two kinds of crosslinked resin fine particles having a specific range of particle diameter in a transparent resin, that is, an average particle diameter of less than 5 μm, preferably 0.1 μm.
1-3 μm crosslinked resin fine particles and average particle size 5-10 μm
m, preferably 5 to 8 μm, is required to be dispersed. Crosslinked resin fine particles having an average particle diameter of less than 5 μm contribute to light diffusivity but mainly impart concealment to the resin, so that light sources such as fluorescent lamps can be seen through when used in applications such as lighting covers. Play a role to prevent. On the other hand, the crosslinked resin fine particles having an average particle diameter of 5 to 10 μm can provide high diffusivity while maintaining the light transmittance of the resin. When only the crosslinked resin fine particles having an average particle diameter of less than 5 μm are used, the opacity is excellent, but the light transmittance is low because it is necessary to increase the amount of the resin fine particles to obtain the desired light diffusing property. Is not preferred. In addition, since the mixing ratio of small particles in the resin increases, when used as lighting equipment, etc.
The transmitted light is undesirably reddish. On the other hand, when only the crosslinked resin fine particles having an average particle diameter of 5 μm or more are used, the light transmittance is high, but the concealing property is insufficient, and the transparency of a light source such as a fluorescent lamp when used as a lighting fixture or the like is poor. In order to prevent this, it is necessary to increase the addition amount, which is not economically preferable.

The amount of the crosslinked resin particles having an average particle diameter of less than 5 μm and the amount of the crosslinked resin particles having an average particle diameter of 5 to 10 μm in the light diffusing resin composition of the present invention does not cause roughening of the surface of the molded article. Considering that the impact strength does not decrease in a practically inconvenient manner, that the secondary workability such as vacuum forming is easy, and that the economy is high, the resin 100
5 parts by weight or less, preferably 3 parts by weight,
It is necessary to be not more than 5 parts by weight, and in consideration of the plate thickness, each is 6 to 30 g / m ² , preferably 8 to ²⁰ g / m ² .
m ² is preferred. The ratio of the added amounts of the two crosslinked resin fine particles having different particle diameter ranges is usually used at a mixing ratio of 1: 1. However, there is no particular limitation, and the ratio can be appropriately adjusted depending on the application.

The light-diffusing resin composition of the present invention can further be mixed and dispersed with an inorganic transparent substance powder, thereby improving the diffusivity and whiteness in reflected light. The inorganic transparent substance powder that can be used in the present invention is not particularly limited, but for example, barium sulfate, calcium carbonate and the like are preferably used. The inorganic transparent material powder has an average particle diameter of 1 to 10 μm, preferably 3 to 10 μm.
-8 μm, and the amount of addition is preferably 5 parts by weight or less based on 100 parts by weight of the resin.
Preferably 0.1 to 3 parts by weight, more preferably 0.1 to 3 parts by weight
Desirably, it is 2 parts by weight. The addition amount of the inorganic transparent substance powder is preferably smaller than the addition amount of the crosslinked resin fine particles from the viewpoint of obtaining high light diffusivity and high light transmittance.

The method for producing the light diffusing resin composition of the present invention is not particularly limited, and it can be produced by, for example, a casting polymerization method, a melt mixing method, or the like. The light-diffusing resin composition of the present invention has a high light-diffusing property and a high light transmittance, so it is suitable as a molding material for lighting covers, lighting signs, displays, glazing, etc.
The lighting fixture, various displays, and glazing products can be manufactured by extrusion molding or the like.

[0015]

Hereinafter, the present invention will be described in detail with reference to examples. In addition, evaluation and the measuring method were implemented by the following methods.

(Measurement of total light transmittance and haze value)
In accordance with IS K6717, it was measured using an integrating sphere light transmittance measuring device (HGM-2DP, manufactured by Suga Test Instruments Co., Ltd.).

(Evaluation of Transmission Characteristics) The relative transmittance was measured using a goniophotometer (GP-1R, manufactured by Murakami Color Research Laboratory).
The diffusion coefficient (D) was calculated from the following equation (1).

[0018]

D = (B ₂₀ + B ₇₀ ) / 2B ₅ (1)

(Where B ₂₀ , B _70, and B ₅ represent the brightness at the light receiving angles x = 20 °, 70 °, and 5 °, respectively, and are values calculated by the following equation (2).

[0020]

Bx = Tx / cosx (2)

In the equation, Bx represents the luminance at the light receiving angle x, and Tx is the relative transmittance (%) at the light receiving angle x when the light transmittance at x = 0 ° (parallel light) is 100%. Represent. )

(Evaluation of Transparency) In the evaluation of translucency, which is a visual judgment of light diffusivity, a sample piece was placed at a position 8 cm in front of a 10 W straight tube fluorescent lamp, and further at a position 1 m away from the sample piece. The observation was made by visually observing whether or not the outline of the fluorescent lamp was visible through the light source. The observation result was indicated by the following symbols. : The outline of the fluorescent lamp is not recognized. Δ: The outline of the fluorescent lamp is slightly recognized. X: The outline of the fluorescent lamp is clearly recognized.

(Measurement of Average Particle Diameter) The average particle diameter (weight average particle diameter) was measured by a particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd .: SKA-5000).

(Example 1) Methyl methacrylate unit 95
% By weight and 5% by weight of methyl acrylate units,
For 100 parts by weight of methacrylic resin having a weight average molecular weight of 160,000, spherical silicone resin fine particles having an average particle diameter of 3 μm (Toshiba Silicone Co., Ltd .: Tospearl 130) and spherical silicone having an average particle diameter of 6 μm Resin fine particles (Toshiba Silicone Co., Ltd .: Tospearl 200)
OB) is mixed, stirred and mixed, and this is mixed with a single screw extruder.
After kneading, melt-extruding and forming into a sheet with a T-die for forming a sheet, the sheet is cooled with a polishing roll to a thickness of 2 mm.
A flat molded article having an excellent appearance was obtained. Table 1 shows the results of evaluating this sheet.

(Example 2) Except that spherical silicone resin fine particles having a particle diameter of 3 µm, spherical silicone resin fine particles having a particle diameter of 6 µm, and calcium carbonate having a particle diameter of 7 µm are used in the proportions shown in Table 1, In the same way as 1,
A flat molded product with good appearance was obtained. Table 1 shows the results of evaluating this sheet.

(Example 3) Styrene crosslinked resin fine particles having a particle diameter of 4 µm (SBX-4, manufactured by Sekisui Chemical Co., Ltd.)
And a styrene crosslinked resin fine particle having a particle diameter of 8 μm (SBX-8, manufactured by Sekisui Chemical Co., Ltd.) at a ratio shown in Table 1, in the same manner as in Example 1 to obtain a flat molded article having a good appearance. Obtained. Table 1 shows the results of evaluating this sheet.

Comparative Example 1 A flat molded product was obtained in the same manner as in Example 1 except that only spherical silicone resin fine particles having a particle diameter of 3 μm were used in the amounts shown in Table 1. The evaluation results of this sheet are shown in Table 1. From the results, it can be seen that the diffusion coefficient is higher but the light transmittance is lower as compared with Example 1.

Comparative Example 2 A flat molded product was obtained in the same manner as in Example 1 except that only spherical silicone resin fine particles having a particle diameter of 6 μm were used in the amounts shown in Table 1. The evaluation results of this sheet are shown in Table 1. From this result, it can be seen that, compared with Example 1, although the light transmittance was high, the diffusion coefficient was low and the light diffusion property was poor.

(Comparative Example 3) Styrene-crosslinked resin fine particles having a particle diameter of 4 μm (SBX-4, manufactured by Sekisui Chemical Co., Ltd.)
A flat molded product was obtained in the same manner as in Example 1 except that only the amount shown in Table 1 was used. The evaluation results of this sheet are shown in Table 1. It can be seen that the diffusion coefficient is almost the same as that of Example 3 but the light transmittance is low.

Comparative Example 4 A flat molded product was obtained in the same manner as in Example 1 except that only the calcium carbonate powder having a particle diameter of 7 μm was used in the amount shown in Table 1. The evaluation results of this sheet are shown in Table 1, and compared with those using the fine particles of the present invention.
It can be seen that the diffusion coefficient is high but the light transmittance is low.

[0031]

[Table 1]

[0032]

As described above, the light-diffusing resin composition of the present invention can be obtained by using a crosslinked resin fine particle having an average particle diameter of less than 5 μm and a crosslinked resin fine particle having an average particle diameter of 5 to 10 μm in combination. High light diffusivity and high light transmittance can be exhibited, and the degree of whiteness can be adjusted by adding an inorganic transparent substance powder as needed in addition to these crosslinked resin fine particles, so that lighting covers, lighting signs, displays It is suitable as a molding material for glazing and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 25:04) (72) Inventor Kiyoshi Takahashi 2-28 Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata Kuraray Co., Ltd. (72) Inventor Minoru Ishiyama 2-28 Kurashiki-cho, Nakajo-machi, Kitakanbara-gun, Niigata Pref. Kuraray Co., Ltd.

Claims (4)

[Claims] An average particle size of 5 parts per 100 parts by weight of a transparent resin.
A light-diffusing resin composition characterized by dispersing crosslinked resin fine particles having a particle size of less than 5 µm or less and crosslinked resin fine particles having an average particle size of 5 to 10 µm in an amount of 5 parts by weight or less. 2. An average particle diameter of 5 parts per 100 parts by weight of the transparent resin.
It is characterized by dispersing the crosslinked resin fine particles of less than 5 μm in an amount of 5 parts by weight or less, the crosslinked resin fine particles having an average particle diameter of 5 to 10 μm in an amount of 5 parts by weight or less, and the inorganic transparent substance powder in an amount of 5 parts by weight or less. Light diffusing resin composition. 3. The light diffusing resin composition according to claim 1, wherein the crosslinked resin fine particles are silicone resin fine particles and / or styrene-based crosslinked resin fine particles. 4. The light diffusing resin composition according to claim 1, wherein the transparent resin is a methacrylic resin.