JPH0790167A - Light-diffusing resin composition - Google Patents

Abstract

PURPOSE:To obtain the title resin having a high total transmittance and excellent light diffusing effect by dispersing a specified amount of particles having specified optical properties, a specified shape and specified properties in an aromatic polycarbonate resin. CONSTITUTION:The title composition is produced by uniformly dispersing 1-10 pts.wt. particles (B) having a refractive index of 1.5 or below and a mean particle diameter of 1-50mum and being incompatible with component A in 100 pts.wt. aromatic polycarbonate (A) (e.g. bisphenol-A-derived polycarbonate resin). A desirable example of component B is a copolymer of methyl methacrylate with a methacrylic crosslinking agent. This composition has a total tranmittance of 85% or higher, a rate of the diffused light transmittance to the total transmittance of 92% or above and an excellent light diffusing effect and can be desirably used for e.g. a liquid crystal diffusion panel of an OA machine.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition containing a thermoplastic aromatic polycarbonate resin as a main component. More specifically, it relates to a light diffusing resin composition effective for a light diffusing effect such as a liquid crystal diffusing panel of OA equipment.

[0002]

2. Description of the Related Art A light-diffusing resin composition having an excellent light-diffusing effect is a composition having a high total light transmittance and a high ratio of the diffuse light transmittance to the total light transmittance. A method is known in which inorganic particles such as glass, calcium carbonate, and silica having a light diffusing effect and a light hiding effect are dispersed in the above excellent resin. Further, as a technique for improving these, as a resin composition containing a thermoplastic aromatic polycarbonate resin as a main component and effective for a light diffusion effect, for example, JP-A-4-161449 or JP-A-4-161.
As disclosed in Japanese Patent No. 448, there is a compound in which styrene-cyclohexylmaleimide crosslinked fine particles or titanium oxide-containing styrene-cyclohexylmaleimide crosslinked fine particles are blended with an aromatic polycarbonate resin.

However, in the prior art, when the total light transmittance is excellent (high), the light diffusion effect, that is, the ratio of the diffuse light transmittance to the total light transmittance (hereinafter, this ratio may be referred to as "haze"). Is poor (low), and the light diffusion effect is excellent, the total light transmittance is low and the composition having an excellent light diffusion effect cannot be obtained because the total light or the like is low (low). .

[0004]

An object of the present invention is to obtain a light diffusing composition having an excellent total light transmittance and an excellent light diffusing effect.

[0005]

As a result of repeated studies to find out a method for solving the above problems, the present inventors have found that a thermoplastic aromatic polycarbonate resin has a specific refractive index and a specific average particle size. It has been found that the problem can be solved by dispersing particles that have the above-mentioned properties and are substantially incompatible with the polycarbonate resin, and have reached the present invention.

That is, in the present invention, (A) the aromatic polycarbonate resin is 90 to 99%, and (B) the refractive index is 1.5.
Particles 0 or less and having an average particle diameter of 1 to 50 μm and substantially incompatible with the aromatic polycarbonate resin 1
It is a light diffusing resin composition consisting of 0 to 1%.

The characteristics of the light diffusing resin composition of the present invention are that the total light transmittance is 85% or more, preferably 90% or more, and the haze is 92% or more, preferably 94% or more. When the total light transmittance is lower than 85%, the brightness of the screen of a liquid crystal diffusion panel or the like is deteriorated, which is not preferable. Further, when the haze is lower than 92%, the sharpness of the screen is deteriorated, which is not preferable.

The thermoplastic aromatic polycarbonate resin (hereinafter sometimes referred to as "PC") used in the present invention is, for example, a bis (4-hydroxyphenyl) alkane compound, particularly a polycarbonate resin containing bisphenol A as a main raw material. And a polycarbonate copolymer obtained by using two or more kinds of aromatic hydroxy compounds in combination, and a branched polycarbonate obtained by using a small amount of trivalent phenol compounds in combination. Further, PC may be used as a mixture of two or more kinds.

In the present invention, particles having a refractive index of 1.50 or less are used as particles to be blended with PC (hereinafter sometimes referred to as "blended particles"). When the refractive index is higher than 1.50, it is difficult to obtain excellent light diffusing property, that is, high haze, which is not preferable. The average particle diameter of the blended particles is 1 to 100 μm, preferably 2 to
It is 50 μm. When the average particle size is smaller than 1 μm, it is difficult to obtain high haze. When the average particle size is larger than 100 μm, it is difficult to obtain a light diffusing resin composition having uniform optical characteristics, which is not preferable. Further, the blended particles are particles that are substantially incompatible with PC. Particles that are compatible with PC are not preferable because it is difficult to obtain excellent light diffusivity because they melt into PC during the compounding process. As the compounded particles having such characteristics, for example, a copolymer of methyl methacrylate and a methacrylic crosslinking agent (manufactured by Sekisui Plastics Co., Ltd.
MB30X-5: average particle diameter 5 μm, refractive index 1.49) is particularly preferable. The copolymerization ratio of the methacrylic crosslinking agent in the copolymer is a ratio capable of suppressing the compatibility with PC, and is, for example, 30 mol%. Incidentally, the particles of polymethylmethacrylate resin (hereinafter sometimes referred to as “PMMA”) having a refractive index of 1.49 have a refractive index of 1.50 or less, but a part thereof is mixed with PC. It is difficult to obtain excellent light diffusivity because it melts.

In the present invention, the compounding ratio of the compounding particles to 100 parts by weight of PC is 1 to 10 parts by weight. Mixing ratio is 1
If it is less than the weight part, it is difficult to obtain a high haze. If the amount is more than 10 parts by weight, the total light transmittance becomes low, which is not preferable.

To the light diffusing resin composition of the present invention, various additives such as flame retardants, stabilizers, colorants, lubricants, etc., or resins other than PC are blended within the range of maintaining the characteristics of the present invention. Good.

To obtain the light diffusing resin composition of the present invention,
Conventionally known methods such as extrusion molding, injection molding, roll kneading, and the like can be used to uniformly disperse the blended particles in the molten PC.

[0013]

According to the present invention, the total light transmittance is 85%.
As described above, the ratio of the diffused light transmittance to the total light transmittance is 9
A light diffusing resin composition having an excellent light diffusion effect of 2% or more can be obtained.

[0014]

The present invention will be described in detail with reference to the following examples. still,
In the examples and the like, "part" means "part by weight". Moreover, various characteristic values were measured by the following methods. Total light transmittance ： Murakami Color Research Laboratory Co., Ltd. H
R-100 type haze meter, ASTM D1
It measured according to 003. Diffused light transmittance: Measured in the same manner as the total light transmittance. Haze: Calculated from the following formula. Haze = (diffused light transmittance / total light transmittance) x 100
[%] Refractive index: Measured with a 2T type Abbe refractometer manufactured by Atago Co., Ltd. Compatibility: The shape and size of the compound particles in the light diffusing resin composition before and after compounding are determined by JSM manufactured by JEOL Ltd.
-6100 type It was observed with a scanning electron microscope and judged as follows depending on the morphology before and after compounding.・ In case of no change: insoluble ・ In case of almost no change: hardly soluble ・ In case of remarkable change: compatible

[0015]

Examples 1 to 4 and Comparative Examples 1 to 2 With respect to 100 parts by weight of a polycarbonate resin (manufactured by Teijin Kasei Co., Ltd., Panlite L-1300, refractive index nD ₂₅ ° C. = 1.589, molecular weight 30,000), Spherical particles composed of a copolymer of methyl methacrylate and a methacrylic cross-linking agent as compounded particles (Techpolymer MB30 manufactured by Sekisui Plastics Co., Ltd.)
X-5: average particle diameter 5 μm, refractive index 1.49, methacrylic crosslinker co-weight ratio 30%) were blended as shown in Table 1, and the mixture was extruded with a 30 mm screw extruder equipped with a sheet extrusion die. , Kneading at the set temperature of 270 ° C,
The molten resin was extruded into a sheet. The molten resin is immediately cooled with a roll that passes cooling water at 30 ° C, and the thickness is 0.3 mm.
Got a sheet of. The properties of the obtained sheet are shown in Table 1.
As is clear from Table 1, when the blending ratio of the blended particles is within the range of the present invention, a light diffusing resin composition having excellent light diffusing properties can be obtained.

[0016]

[Table 1]

[0017]

[Example 5 and Comparative Examples 3 to 7] As the compounded particles, those shown in Table 2 were used in an amount of 3 per 100 parts by weight of the polycarbonate resin.
A sheet was obtained in the same manner as in Example 1 except that the parts by weight were compounded.
The characteristics of the obtained sheet are shown in Table 2. As is clear from Table 2, when the characteristics of the blended particles are within the range of the present invention, a light diffusing resin composition having excellent light diffusing characteristics can be obtained.
That is, when the compounded particles within the range of the present invention of Example 5 were used, a light diffusing resin composition having excellent characteristics was obtained, whereas in the case of Comparative Examples 3 to 6 in which the refractive index was out of the range, In the case of Comparative Example 7 in which the haze is inferior and the compatibility with PC is out of the range, the haze is inferior and a light diffusing resin composition having excellent light diffusing properties cannot be obtained. The average particle diameters of the various compounded particles in Table 2 are MB30X-5: 5 μm, polystyrene-based crosslinked particles: 8 μm, glass beads: 10 μm, titanium oxide particles: 2 μm, calcium carbonate: 5 μm, PMMA resin:
The one having a thickness of 4 μm was used.

[0018]

[Table 2]

[0019]

Examples 1 and 6, Comparative Examples 8 and 9 Sheets were obtained in the same manner as in Example 1 except that the average particle size of the compound particles was changed. The properties of the obtained sheet are shown in Table 3. As is clear from Table 3, if the particle size of the compound particles is outside the range of the present invention, a light diffusing resin composition having excellent light diffusing properties cannot be obtained.

[0020]

[Table 3]

[0021]

Example 7 and Comparative Example 10 Sheets were molded in the same manner as in Example 1 and Comparative Example 2. Table 4 shows the measurement results of various properties other than the optical properties of the obtained sheet. As is clear from Table 4, the mechanical properties and thermal properties of the sheet made of the light diffusing resin composition of the present invention are substantially the same as those of the sheet made of the polycarbonate resin containing no added particles. .

[0022]

[Table 4]

Claims (2)

[Claims] 1. (A) Aromatic polycarbonate resin 10
0 parts by weight and (B) 1-10 parts by weight of particles having a refractive index of 1.50 or less, an average particle size of 1 to 50 μm, and substantially incompatible with the aromatic polycarbonate resin. Resin composition. 2. The light diffusing resin composition according to claim 1, wherein the particles that are substantially incompatible with the aromatic polycarbonate resin are a copolymer of methyl methacrylate and a methacrylic crosslinking agent.