JPH083434A - Polycarbonate resin composition and optical sheet - Google Patents

Abstract

PURPOSE:To produce a polycarbonate resin composition suitable as a material for extruding a molded article of complicated fine shape and obtain an optical sheet made therefrom and excellent in optical characteristics by using a linear polycarbonate resin and a branched polycarbonate resin at a specified ratio. CONSTITUTION:This composition contains 80-99.5wt.% polycarbonate resin consisting of 20-95wt.% linear polycarbonate resin and 5-80wt.% branched polycarbonate resin and 0.5-20wt.% styrene resin. As the styrene resin, a styrene/ butadiene block copolymer is preferably used. By using the polycarbonate resin of the above-mentioned constitution comprising a linear polycarbonate resin and a branched polycarbonate resin, a lens shape can be precisely formed and an optical sheet useful for, e.g. a projection screen can be produced. As mentioned above, 0.5-20wt.% styrene resin may be incorporated into the polycarbonate resin then.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin composition containing a linear polycarbonate resin and a branched polycarbonate resin and an optical sheet comprising the resin composition. More specifically, the present invention relates to a complex and fine shape. A polycarbonate resin composition that can be accurately extrusion molded even if it has a molded article, and a projection used as a screen for lighting equipment covers, decorative plates having a decorative pattern optical effect, displays, projection televisions, microfilm readers, etc. The present invention relates to an optical sheet used as a screen or the like, and particularly to an optical sheet in which fine uneven lenses are formed on at least one surface of the sheet.

[0002]

2. Description of the Related Art Optical sheets used for lighting fixture covers, decorative plates having a decorative pattern optical effect, displays, projection screens and the like have fine uneven lenses formed on at least one surface of the sheet. The light is diffused by the lens effect. For example, a projection screen such as a transmissive screen or a reflective screen is widely used to project a television image, a microfilm image, or the like to realize a desired display. This type of projection screen is provided with a lens of a predetermined shape on the entrance surface and / or the exit surface so that the viewer is bright when observing, and the viewing angle is widened. Generally, a lenticular lens is used. .

In particular, in a double-sided lenticular lens having lens shapes on both the entrance surface and the exit surface, misalignment of the axes of the lenses on both surfaces adversely affects the screen characteristics, so that good screen characteristics are obtained. Requires precise alignment of the lenticular lenses on both sides. However, the double-sided lenticular lens is manufactured by a method such as an extrusion molding method, a casting method by cell casting, or a heat pressing method, and these all directly transfer a metal mold or the like to a resin plate. It is difficult to accurately perform the dimensional accuracy of the master mold, mold temperature control during molding, and positioning of the double-sided master mold, and it was difficult to sufficiently improve the positioning accuracy of the double-sided lenticular lens. .

On the other hand, in large televisions, there is an increasing demand for higher definition, and the lenticular lens of the projection screen is also required to have a fine pitch. However, in the conventional manufacturing method as described above,
It is not easy to make a fine pitch with a double-sided lenticular lens of about 1 meter square by reducing the displacement of the lens positions on the front and back sides, and it has not been possible to sufficiently meet the demand for a fine pitch. Therefore, the applicant of the present invention, as disclosed in Japanese Patent Laid-Open No. 3-200948, makes adjacent orifices for forming a light-transmissive strand close to each other at a small interval, and the molten resin expands in the radial direction immediately after spun from the orifice. It proposes a method of manufacturing a projection screen in which adjacent translucent strands are fused together by the phenomenon of becoming transparent (Belas effect).

In such a projection screen, polymethylmethacrylate, polycarbonate, polyvinyl chloride, polystyrene and the like, which have good transparency and excellent workability, are used. Among them, polymethyl methacrylate, which is excellent in transparency and processability, is widely used.
However, projection screens installed in vehicles such as airplanes and public places are required to be flame retardant from the viewpoint of disaster prevention, and have excellent mechanical properties such as impact resistance and heat resistance. In addition to excellent dimensional stability such as resistance and water resistance, a polycarbonate resin having excellent flame retardancy has been used. Generally, polycarbonate resins are excellent in transparency, impact resistance, heat resistance and the like, and are widely used in various fields. In particular, the branched polycarbonate-based resin has a greater shear rate dependence of viscosity than the linear polycarbonate-based resin, and is a material suitable for extrusion molding and is widely used.

[0006]

However, since the polycarbonate resin has a high extrusion processing temperature of 280 to 300 ° C. and a high viscosity, the load on the screw of the extruder is large, and the resin has a complicated and fine shape. In the extrusion molding of the molded product, the discharge amount was limited and the workability was poor. Further, when an optical sheet is manufactured using a linear polycarbonate resin, a sheet is easily melt-extruded using a T-die or the like, and the sheet tends to draw down due to a decrease in extensional viscosity. It was very difficult to get. In particular, in the case of an optical sheet such as a lenticular lens sheet that forms a complicated and fine concave-convex lens shape on the sheet surface, the lens shape is not accurately formed, and an optical sheet having the designed optical characteristics is obtained. It had a problem that it was hard to be caught.

Further, a large number of translucent plastic strands as described in JP-A-3-200948 are arranged in parallel, and adjacent translucent strands are joined to be integrated into a sheet. In optical sheets used for projection screens, etc., if linear polycarbonate resin is used as the material of the translucent strand,
A sheet formed by fusing adjacent translucent strands spun from the orifice, draws down each translucent strand, that is, the lenticular lens is flattened,
There is a problem that the optical characteristics of the optical sheet are deteriorated. The present invention, even when using a polycarbonate-based resin as a material for extrusion molding of a molded product having a complicated and fine shape, provides a polycarbonate resin composition having excellent processability that can be accurately extrusion-molded,
It is an object of the present invention to provide an optical sheet which is capable of accurately forming a lens shape without lowering the extensional viscosity of a polycarbonate resin and which has excellent optical characteristics.

[0008]

In view of such a situation, the inventors of the present invention have diligently studied a polycarbonate resin composition excellent in moldability and a material constituting an optical sheet using the same, and as a result, the present invention was obtained. Has reached.
That is, the polycarbonate resin composition of the present invention comprises 80 to 99.5 wt% of a polycarbonate resin consisting of 20 to 95 wt% of a linear polycarbonate resin and 5 to 80 wt% of a branched polycarbonate resin and 0.5 of a styrene resin. It is characterized by containing ~ 20 wt%. Further, the optical sheet of the present invention is characterized by comprising 20 to 95% by weight of a linear polycarbonate resin and 5 to 80% by weight of a branched polycarbonate resin.

First, the polycarbonate resin composition of the present invention will be described. The polycarbonate resin composition of the present invention contains a linear polycarbonate resin, a branched polycarbonate resin and a styrene resin,
Contains 80 to 99.5% by weight of a polycarbonate resin consisting of 20 to 95% by weight of a linear polycarbonate resin and 5 to 80% by weight of a branched polycarbonate resin, and 0.5 to 20% by weight of a styrene resin. It will be.
The linear polycarbonate-based resin and the branched polycarbonate-based resin used in the present invention are not particularly limited, and commonly used resins can be used.

The linear polycarbonate-based resin is a linear aromatic polycarbonate-based resin produced by a known phosgene method or a melting method, and comprises a carbonate component and a diphenol component. As the precursor for introducing the carbonate component, for example, phosgene,
Examples thereof include diphenyl carbonate. Examples of dipheninol include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3,5- Dimethyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (3,5-dimesyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (4-
Hydroxyphenyl) decane, 1,4-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclodecane, 1,1-bis (3,5-
Dimethyl-4-hydroxyphenyl) cyclododecane,
4,4-dihydroxydiphenyl ether, 4,4-thiodiphenol, 4,4-dihydroxy-3,3-dichlorodiphenyl ether, 4,4-dihydroxy-2,
5-dihydroxy diphenyl ether etc. are mentioned.
These can be used alone or in combination of two or more.

Specific examples include those having about 10 to 400 repeating units represented by the following general formula (1).

[0012]

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Wherein A is a divalent aromatic group,
Specifically, the following (2) to (6) can be exemplified.

[0014]

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[0015]

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[0016]

[Chemical 4]

[0017]

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[0018]

[Chemical 6]

Such a linear polycarbonate resin is produced, for example, by the method described in US Pat. No. 3,989,672, and has a refractive index of 1.57 to 1.5.
9 is preferable. In the present invention, a linear polycarbonate produced by the reaction of bisphenol A and phosgene, that is, A in the above general formula (1) is an aromatic group of the above (6) and the number of repeating units is 40.
A refractive index of about 400 with a refractive index of about 1.58 is preferred. Further, as the linear polycarbonate-based resin, a copolymerized polycarbonate-based resin having the structural units represented by the following general formulas (7) and (8) can also be used.

[0020]

[Chemical 7]

[0021]

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(In the formula, R and R'are each independently a halogen atom, a monovalent hydrocarbon group or a hydrocarbon oxy group, and X is a divalent hydrocarbon group, -S-, -S-. S
-, -O-, -S (= O)-,-(O =) S (= O)-
Or -C (= O)-, n and m are each independently an integer of 0 to 4, Y is a divalent aliphatic group having 6 to 18 carbon atoms, and q is 0 or 1. . The structural unit represented by the general formula (7) is composed of a diphenol component and a carbonate component. The diphenol that can be used for introducing the diphenol component is a diphenol represented by the following general formula (9).

[0023]

[Chemical 9]

(In the formula, R and R'are each independently a halogen atom, a monovalent hydrocarbon group or a hydrocarbon oxy group, and X is a divalent hydrocarbon group, -S-, -S-. S
-, -O-, -S (= O)-,-(O =) S (= O)-
Or -C (= O)-, n and m are each independently an integer of 0 to 4, Y is a divalent aliphatic group having 6 to 18 carbon atoms, and q is 0 or 1. . ) In the diphenol represented by the general formula (9), R
Examples of the monovalent hydrocarbon group of R'and R'include, for example, an alkyl group having 1 to 12 carbon atoms such as a methyl group, a propyl group and a decyl group, and a cycloalkyl group having 4 to 8 carbon atoms such as a cyclopentyl group and a cyclohexyl group. Aryl groups having 6 to 12 carbon atoms such as phenyl group, naphthyl group and biphenyl group, aralkyl groups having 7 to 14 carbon atoms such as benzyl group, cinnamyl group, etc., and alkyl groups having 1 to 14 carbon atoms such as tolyl group and cumenyl group. Examples thereof include reel groups, and among them, alkyl groups are preferable. Further, a hydrocarbon oxy group such as an alkoxy group, a cycloalkyloxy group, an aryloxy group, an aralkyloxy group, an alkaryloxy group and the like can be mentioned, and an alkoxy group or an aryloxy group is preferable. In the general formula (9), examples of the divalent hydrocarbon group represented by X include an alkylene group having 1 to 30 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, and an octamethylene group, an ethylidene group, and a propylidene group. Examples thereof include a cycloalkylene group having 6 to 16 carbon atoms such as an alkylidene group having 2 to 30 carbon atoms, a cyclohexylene group, and a cyclododecylene group, and a cycloalkylidene group.

Specific examples of the diphenol include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane and 2,2-. Bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-
Bis (3,5-dimesyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) decane, 1,4-bis (4-hydroxyphenyl)
Propane, 1,1-bis (4-hydroxyphenyl) cyclodecane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclododecane, 4,4-dihydroxydiphenyl ether, 4,4-thiodiphenol,
4,4-dihydroxy-3,3-dichlorodiphenyl ether, 4,4-dihydroxy-2,5-dihydroxydiphenyl ether and the like can be mentioned. These can be used alone or in combination of two or more. Further, as the precursor for introducing the carbonate component,
Examples thereof include phosgene and diphenyl carbonate.

The structural unit represented by the above general formula (8) is
It consists of a diphenol component and a divalent acid component. As the diphenol that can be used for introducing the diphenol component, the same ones as described above can be used. The monomer that can be used for introducing the divalent acid component is a divalent acid or an equivalent substance thereof, which may be linear, branched or cyclic and has 8 to 20 carbon atoms. Acids, preferably aliphatic diacids having 10 to 12 carbon atoms are mentioned. Specific examples thereof include linear saturated aliphatic dicarboxylic acids such as sebacic acid, dodecanedioic acid, tetradodecanedioic acid, octadecanedioic acid, and eicosanedioic acid, and among them, sebacic acid and dodecanedioic acid are preferable. Examples of equivalent substances include acid halides such as acid chlorides of the above divalent acids, specifically diaromatic esters such as diphenyl esters (where the carbon number of the ester portion is Not included in the carbon number of the acid). These can be used alone or in combination of two or more.

In the copolymerized polycarbonate resin, the structural unit represented by the general formula (8) is preferably 2 to 30 mol%, more preferably 5 to 25 mol%,
Particularly preferably, it is 7 to 20 mol%. In the present invention, the linear polycarbonate resin is contained in the polycarbonate resin in the range of 20 to 95% by weight, preferably 40 to 90% by weight. This is because when the content of the linear polycarbonate resin is less than 20% by weight, the shear viscosity of the resin is increased and the moldability is deteriorated.
This is because if it exceeds 5% by weight, the extensional viscosity is lowered and molding by extrusion molding becomes difficult.

As the linear polycarbonate resin such as the copolymerized polycarbonate resin used in the present invention, it is preferable to use one having a number average molecular weight in the range of 16000 to 27,000, more preferably 180.
The range is from 00 to 26000. This is because when the number average molecular weight of the linear polycarbonate-based resin is less than 16000, the shear viscosity of the resin composition is remarkably reduced, and drawdown of the sheet tends to occur. On the other hand, when it exceeds 27,000, the shear viscosity of the resin composition becomes high, and the productivity of the molded product by extrusion tends to decrease. In the present invention, a low-molecular weight linear polycarbonate-based resin and a high-molecular weight linear polycarbonate-based resin may be mixed at an appropriate ratio and adjusted to a desired number average molecular weight before use.

The branched polycarbonate resin used in the present invention is a polycarbonate resin produced by using a branching agent, and examples of the branching agent include phloroglysin, trimellitic acid, 1,1,1-tris. (4-hydroxyphenyl) ethane, 1,1,2-tris (4-
Hydroxyphenyl) ethane, 1,1,2-tris (4
-Hydroxyphenyl) propane, 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1-tris (4-hydroxyphenyl) ethane, 1,1,1-tris (4-hydroxyphenyl) propane , 1,1,1
-Tris (2-methyl-4-hydroxyphenyl) methane, 1,1,1-tris (2-methyl-4-hydroxyphenyl) ethane, 1,1,1-tris (3-methyl-)
4-hydroxyphenyl) methane, 1,1,1-tris (3-methyl-4-hydroxyphenyl) ethane, 1,
1,1-tris (3,5-dimethyl-4-hydroxyphenyl) methane, 1,1,1-tris (3,5-dimethyl-4-hydroxyphenyl) ethane, 1,1,1-tris (3- Chloro-4-hydroxyphenyl) methane,
1,1,1-tris (3-chloro-4-hydroxyphenyl) ethane, 1,1,1-tris (3,5-dichloro-4-hydroxyphenyl) methane, 1,1,1-tris (3,3 5-dichloro-4-hydroxyphenyl) ethane, 1,1,1-tris (3-bromo-4-hydroxyphenyl) methane, 1,1,1-tris (3-bromo-)
4-hydroxyphenyl) ethane, 1,1,1-tris (3,5-dibromo-4-hydroxyphenyl) methane, 1,1,1-tris (3,5-dibromo-4-hydroxyphenyl) ethane, etc. Can be mentioned.

Such a branched polycarbonate resin is, for example, as described in Japanese Patent Application No. 1-321552, a polycarbonate oligomer derived from an aromatic diphenol, the above branching agent and phosgene, and an aromatic compound. The diphenols and the end terminator are reacted with stirring so that the reaction mixture containing them becomes turbulent, and when the viscosity of the reaction mixture increases, an aqueous alkali solution is added and the reaction mixture is laminarly flowed. Can be produced by the method of reacting as. The branched polycarbonate resin of the resin composition of the present invention is contained in the polycarbonate resin in the range of 5 to 80% by weight, preferably 10 to 60% by weight. This is because when the content of the branched polycarbonate resin is less than 10% by weight, the extensional viscosity is lowered and the molding by extrusion molding becomes difficult, and when it exceeds 80% by weight, the shear viscosity of the resin is increased and the moldability is deteriorated. This is because

In the present invention, the styrene resin is contained together with the above polycarbonate resin to reduce the shear viscosity of the resin composition and to form a molded product having a complicated and fine shape by extrusion molding. Workability can be improved. The content of styrene resin is in the range of 0.5 to 20% by weight, preferably 1 to
It is in the range of 10% by weight. This is because when the styrene-based resin is less than 0.5% by weight, the shear viscosity of the resin composition increases and the moldability of a molded product having a complicated and fine shape by extrusion molding decreases, and when it exceeds 20% by weight. This is because the flame retardancy, weather resistance, heat resistance, etc. of the molded product are reduced.

Examples of the styrene resin used include polystyrene resin, high impact polystyrene resin, styrene-maleic anhydride copolymer, acrylonitrile.
Styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, styrene-butadiene-styrene (SBS) resin, styrene-butadiene rubber (S
BR) resin, styrene / ethylene / butadiene / still (SEBS) resin and the like. Specific examples of the polystyrene resin include polymers composed of styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, chlorostyrene and other substituted monovinylaromatic monomers. The impact-resistant polystyrene resin is a polymer obtained by dissolving or mixing a rubber-like elastic material in a monovinyl aromatic monomer and polymerizing. Examples of the rubber-like elastic body include a rubber-like elastic body containing polybutadiene, acrylate and / or methacrylate, styrene / butadiene / styrene resin, acrylonitrile / styrene / butadiene resin, acrylonitrile / styrene resin, styrene / butadiene rubber, butadiene / butadiene rubber. Examples thereof include acrylic rubber, isoprene rubber, isoprene / styrene rubber, isoprene / acrylic rubber, ethylene / propylene rubber and the like.

Among them, the styrene resin is preferably a block copolymer of styrene and butadiene such as styrene / butadiene / styrene (SBS) resin. The ratio of styrene to butadiene is not particularly limited, but the content of butadiene is preferably about 15 to 75% by weight, and more preferably 20 to 60% by weight. Incidentally, in the present invention, if necessary, a colorant,
Additives such as a light diffusing agent, a light stabilizer, and a heat deterioration preventing agent may be added.

Next, the optical sheet of the present invention will be described. The optical sheet of the present invention is composed of a resin composition containing a linear polycarbonate resin and a branched polycarbonate resin, and contains 20 to 95% by weight of the linear polycarbonate resin and 5 to 5% of the branched polycarbonate resin.
The polycarbonate resin composition comprises 80% by weight. The linear polycarbonate-based resin and the branched polycarbonate-based resin used are not particularly limited, and those which are commonly used can be used. Specifically, the linear polycarbonate-based resin and the branched polycarbonate-based resin described above are used. Can be used. In an optical sheet having a complicated and fine shape such as a double-sided lenticular lens sheet, using a copolycarbonate resin as the linear polycarbonate resin lowers the shear viscosity of the resin composition and lowers the nozzle pressure. It is preferable for such reasons.

In the present invention, the linear polycarbonate resin is contained in the polycarbonate resin in the range of 20 to 95% by weight, preferably 40 to 90% by weight, more preferably 70 to 90% by weight. This is because when the content of the linear polycarbonate resin is less than 20% by weight, the shear viscosity of the resin becomes high and the productivity of the optical sheet decreases, and when it exceeds 95% by weight, the extensional viscosity of the optical sheet decreases and the productivity of the sheet decreases. This is because drawdown is likely to occur, it becomes difficult to form an accurate lens shape, and the optical characteristics deteriorate.

In particular, in an optical sheet such as a projection screen in which a large number of light-transmissive plastic-based strands are arranged in parallel and adjacent light-transmissive strands are joined and integrated into a sheet, When the chain polycarbonate resin is less than 20% by weight, the shear viscosity of the resin for forming the translucent strand becomes high, and the nozzle may be cracked due to an increase in nozzle pressure, or the nozzle may be cracked or broken. Or the resin's balus effect becomes too large, and the contact length of the translucent strands (contact length of adjacent lenses) becomes long, the viewing angle as a projection screen becomes narrow, and the color balance deteriorates and the optical balance This is because the optical characteristics of the sheet deteriorate. On the other hand, if the linear polycarbonate resin exceeds 95% by weight, the elongational viscosity of the resin decreases and the sheet having the translucent strands fused is apt to draw down, and the translucent strands are flattened (lens thickness). However, the viewing angle of the projection screen becomes narrower, the color balance deteriorates, the optical characteristics of the optical sheet deteriorate, and the resin's veiling effect decreases and the adjacent transparent film becomes smaller. This is because the fusion of the optical strands becomes insufficient and it becomes difficult to form a sheet, or the sheet easily tears.

The branched polycarbonate resin used in the optical sheet of the present invention is contained in the polycarbonate resin in the range of 5 to 80% by weight, preferably 5 to 80% by weight.
The range is 60% by weight, more preferably 5 to 30% by weight. This is 5% by weight of branched polycarbonate resin
If the amount is less than 80% by weight, sheet drawdown is likely to occur, it is difficult to transfer an accurate lens shape and the optical characteristics are deteriorated. If it exceeds 80% by weight, the shear viscosity of the resin is increased and the optical sheet productivity is increased. This is because the

Particularly, in an optical sheet such as a projection screen in which a large number of light-transmissive plastic-based strands are arranged in parallel and adjacent light-transmissive strands are joined and integrated into a sheet, When the polycarbonate-based resin exceeds 80% by weight, the shear viscosity of the resin for forming the light-transmissive strand becomes high, which may cause cracks in the nozzle due to an increase in nozzle pressure, or may lead to chipping or cracking. , The resin's bolus effect becomes too large, and the contact length of the translucent strands increases,
This is because the viewing angle as the projection screen becomes narrower, the color balance becomes worse, and the optical characteristics of the optical sheet deteriorate. On the contrary, if the branched polycarbonate resin is less than 5% by weight, the elongational viscosity of the resin is lowered, and drawdown of the sheet having the translucent strands fused is likely to occur.
The translucent strands tend to be flattened, the viewing angle of the projection screen becomes narrower, the color balance deteriorates, the optical characteristics of the optical sheet deteriorate, and the resin's veiling effect decreases, resulting in adjacent translucency. This is because the fusion of the strands becomes insufficient and it becomes difficult to form a sheet, or the sheet easily tears.

The linear polycarbonate resin such as the copolymerized polycarbonate resin used in the present invention preferably has a number average molecular weight of 16,000 to 27,000, more preferably 180.
The range is from 00 to 26000. This is because when the number average molecular weight of the linear polycarbonate resin is less than 16000, the shear viscosity of the resin composition is remarkably reduced, drawdown of the sheet is likely to occur, and it becomes difficult to form an accurate lens shape. This is because the properties tend to decrease, and when it exceeds 27,000, the shear viscosity of the resin composition increases, and the productivity of the optical sheet tends to decrease.

In particular, in an optical sheet such as a projection screen in which a large number of translucent plastic-based strands are arranged in parallel and adjacent translucent strands are joined and integrated into a sheet, When the number average molecular weight of the chain polycarbonate resin is less than 16000,
The shear viscosity of the resin composition is remarkably reduced, and the drawdown of the sheet having the translucent strands fused is likely to occur, the translucent strands are flattened, and the viewing angle as a projection screen is narrowed, or the color balance is reduced. Of the resin composition tends to deteriorate and the optical properties of the resin composition tend to deteriorate, and it becomes difficult to form a sheet due to insufficient fusion of adjacent translucent strands of the resin composition, or the sheet tends to tear. Because there is. On the other hand, when the number average molecular weight exceeds 27,000, the shear viscosity of the resin composition becomes high, which may cause cracks in the nozzle due to an increase in the nozzle pressure, chipping, cracking, and the like, and the resin balas effect is large. This is because the contact length of the translucent strands becomes long, the viewing angle of the projection screen becomes narrow, and the color balance tends to deteriorate and the optical characteristics tend to deteriorate.

In the present invention, the styrene resin as described above may be contained in the range of 0.5 to 20% by weight together with the polycarbonate resin as described above. The styrene-based resin can reduce the shear viscosity of the resin composition and the nozzle pressure. Particularly, in an optical sheet such as a projection screen in which a large number of light-transmissive plastic strands are arranged in parallel and adjacent light-transmissive strands are joined and integrated in a sheet shape, the method disclosed in Japanese Patent Application Laid-Open No. As described in Japanese Patent Publication No. 2009948, since a nozzle in which a large number of orifices are continuously formed at small intervals is used, the strength of the nozzle on the line in which the orifice is formed is weakened, and the shear viscosity of the resin is reduced. As the nozzle pressure rises due to the rise, the nozzle is likely to be cracked, chipped, or cracked. Therefore, it is important to lower the nozzle pressure by blending the styrene resin.

When a styrene resin is used, the amount used is preferably in the range of 0.5 to 20% by weight, more preferably 1 to 10% by weight. This is because when the content of the styrene-based resin is less than 0.5% by weight, the shearing viscosity of the resin composition is reduced and the nozzle pressure is not sufficiently added, which is not sufficient. On the contrary, when the styrene resin is contained in an amount of more than 20% by weight, the flame retardancy, weather resistance, heat resistance and the like of the optical sheet tend to be lowered. In addition,
The optical sheet of the present invention may be a colored and transparent sheet in which an appropriate coloring agent is mixed, or may be a sheet in which a light diffusing agent is mixed in the whole or in a layer form. Further, if necessary, additives such as a light stabilizer and a heat deterioration preventing agent may be added.

When the optical sheet of the present invention is used as a projection screen or the like, in order to widen the visual field range,
(Meth) acrylic resin, styrene resin, styrene-
A diffusing agent composed of fine particles such as (meth) acrylate resin is often used. However, when the styrene resin and the diffusing agent composed of resin fine particles are simultaneously mixed in the polycarbonate resin composition, the compatibility with the diffusing agent composed of resin fine particles is poor, and the shear viscosity of the resin composition is significantly lowered. Seat drawdown is more likely to occur. In particular, in an optical sheet such as a projection screen in which a large number of light-transmissive plastic strands are arranged in parallel and adjacent light-transmissive strands are joined to form a sheet, the elongation viscosity of the resin Of the sheet with the translucent strands fused to each other tends to draw down, the translucent strands tend to be flattened, the viewing angle of the projection screen becomes narrower, and the color balance deteriorates. The optical characteristics of the above tend to deteriorate.

Therefore, when the diffusing agent composed of resin fine particles is used, it is preferable to avoid the use of the styrene resin and use the above-mentioned copolymeric polycarbonate resin as the linear polycarbonate resin. By using the copolycarbonate-based resin, the nozzle pressure can be lowered without causing an extreme decrease in the shear viscosity of the resin composition even if a diffusing agent composed of resin fine particles is used. The optical sheet of the present invention is, for example, one in which adjacent plastic-based light-transmissive strands 1 are joined and a large number of light-transmissive strands 1 are arranged in parallel as shown in FIG. Is. When used as a projection screen, a light absorber 2 made of an acrylic resin or the like containing a dye-based or carbon black-based light absorber is usually formed between each translucent strand 1. ing.

Such a projection screen is manufactured by the melt extrusion method in principle.
An example of manufacturing the projection screen of the present invention will be described with reference to FIG. In FIG. 2, 3 is an extruder, 4 is a nozzle holder equipped with a nozzle, and a mixture of molten polycarbonate resin is discharged from an orifice. The discharge direction is
Either upward or downward may be used, but it is preferable to eject the liquid upward so that the light-transmissive strands are made uniform and the pitch is set. As the nozzle, for example, the one in which the orifices 12 and 13 as shown in FIGS. 3 and 4 (a partially enlarged view of FIG. 3) are arranged in a substantially horseshoe shape is used. The orifice 12 discharges a polycarbonate resin for forming a light-transmissive strand, and the orifice 13 discharges a mixture of an acrylic resin for a light absorber and a light absorber.

The annular sheet 5 of the translucent strands of the polycarbonate resin thus discharged has the adjacent translucent strands formed by the viscous effect in which the molten polycarbonate resin expands in the radial direction immediately after being spun from the orifices 12. It is fused and integrated, and a light absorber is formed between the respective light-transmissive strands on one surface thereof, and is pulled up along the inner wall of the annular guide 6, and the trowel-shaped guide 7 and the rod-shaped straight guide 8 form an annular sheet. Is spread on a flat sheet, and at the same time the advancing direction of the sheet is changed by a rod-shaped straight guide, and the sheet is taken up by a nip roller 9 and wound on a reel 10. If necessary, the sheet may be subjected to a slight heat extension.

The cross-sectional shape of the translucent strand 1 of the obtained projection screen can be appropriately selected from various shapes such as a substantially oval shape, a circular shape or a daruma shape, depending on the nozzle cross-sectional shape and the spinning conditions. The pitch of the light-transmissive strands 1 is about 0.1 to 1.5 mm, although it varies depending on the use and purpose of the screen, and it is sufficiently compatible with the fine pitch of the screen. Furthermore, the outer surface of the light-transmissive strand 1 may be smooth, or may be formed with fine irregularities to prevent external light from being reflected. The optical sheet of the present invention is preferably formed of a single sheet, but may be formed by connecting a plurality of sheets. When used as a projection screen, it can also be used as a configuration in which a Fresnel lens or a lens sheet in which a Fresnel lens and a lateral lenticular lens are combined is used together on the light source side.

[0048]

EXAMPLES The present invention will be specifically described below with reference to examples. Examples 1 to 10 Using the resin compositions having the compounding compositions shown in Table 1, the nozzles shown in FIGS. 3 and 4 were used to produce projection screens with the apparatus shown in FIG. The nozzle has 10 orifices 12 with a hole diameter of 1 mm for the translucent strand at a pitch of 1.25 mm.
00 pieces are arranged in a ring shape, and between the orifices 12, there are arranged the orifices 13 having a hole diameter of 0.5 mm for the light absorber.

A mixed melt of the resin composition was supplied to the orifice 12 at 0.2 g / min per orifice, and the orifice 13 was made of polymethylmethacrylate (VH manufactured by Mitsubishi Rayon Co., Ltd.) with 4% by weight of inorganic silica and carbon black 2.
The mixed melt with the addition of wt.
02 g / min was supplied and the mixture was extruded upward at a nozzle temperature of 250 ° C. The nozzle pressure at this time was sufficiently low so that cracks, chips, cracks, etc. did not occur in the nozzle.
After extruding, the trowel-shaped guide 7 and the rod-shaped straight guide 8 are pulled up along the inner wall of the annular guide 6 at a speed of 1.3 m / minute, while the annular sheet 5 formed by fusion of the adjacent translucent strands is pulled up. Was developed into a flat sheet and wound up on the reel 10. The sheet was cooled by passing warm water of 40 ° C. into each guide.

At this time, the degree of drawdown of the annular sheet 5 was visually evaluated according to the following criteria, and the results are shown in Table 1. ◯: Drawdown is hardly observed. Δ: Some drawdown was observed. X: Drawdown is remarkable.

The three sheets wound on the reel 10 are taken up by using the first nip roller, and the ambient temperature is set to 14
Pass through the first far-infrared heater at 0 ° C. while extending it 1.05 times by the second nip roller,
The winding habit of the sheet was removed. Then, the ambient temperature 16
After passing through a second far-infrared heater at 0 ° C. while being stretched 1.1 times using a third nip roller,
It was cut to a length of 1 m with a cutter. The obtained sheet is
1000 light-transmissive strands were completely fused and integrated at a pitch of 0.4 mm and uniformly arranged in a plane, and a light absorber was formed between the light-transmissive strands. Further, the lens shape of the translucent strand of the obtained sheet, visually evaluate the flattened state and contact length according to the following criteria,
The results are shown in Table 1.

Flattened state ◯: Flattening is hardly recognized. X: The flattening is remarkable. Contact length A : The contact length is appropriate and the optical characteristics are extremely excellent. ◯: The contact length is appropriate and the optical characteristics are excellent. X: Long contact length and poor optical properties.

On the other hand, the resin composition having the compounding composition shown in Table 1 was melt-kneaded at a temperature of 260 ° C. and a rotation speed of 100 rpm using a co-directional twin-screw extruder (PCM-30 manufactured by Ikegai Iron Works Co., Ltd.) to form pellets. It was created. The obtained pellets were melted and supplied at 0.25 g / min per orifice of the extruder, and the head temperature was 250 ° C and the nozzle temperature was 250 ° C.
The sheet was extruded. At this time, a resin pressure gauge manufactured by Nagano Keiki Co., Ltd. was installed in the resin flow path immediately before the nozzle to measure the nozzle pressure, and the results are shown in Table 1. Further, using a capillary rheometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) having a length of 10 mm and a diameter of 1 mm, the die swell (degree of baler effect: diameter of the capillary (D ₀ ) to the diameter (D) of the sample extruded from the capillary (D / D ₀ ))
Was measured and the results are shown in Table 1. In the present invention, the die swell is preferably in the range of 1.1 to 1.3, more preferably 1.15 to 1.2. This projection screen was combined with a Fresnel lens to form a transmissive screen, which was then attached to a color projection TV for observation, but it had a wide viewing angle, was optically uniform without screen spots, and had good color balance and contrast. An image was obtained.

[0054]

[Table 1]

Comparative Examples 1 to 7 Using the resin compositions having the composition shown in Table 2, Example 1
A sheet was manufactured in the same manner as in Example 1 by using the same nozzle and apparatus as those in. At this time, the degree of drawdown of the annular sheet 5 and the lens shape of the translucent strand of the obtained sheet (flattened state and contact length) were evaluated, and the results are shown in Table 2. The nozzle pressure and die swell were measured in the same manner as in Example 1, and the results are shown in Table 2. In Comparative Examples 2, 3 and 7, the nozzle pressure was extremely high and extrusion molding was impossible,
I couldn't make a seat. Comparative Examples 1, 4, 5 and 6 A Fresnel lens was combined with the obtained projection screen to form a transmissive screen, which was attached to a color projection television and observed. However, the viewing angle was narrow and the color balance was poor, so that it was at a practical level. The optical characteristics of were not obtained.

Reference Example 1 Using the resin composition having the composition shown in Table 2, Example 1
A sheet was manufactured in the same manner as in Example 1 by using the same nozzle and apparatus as those in. At this time, the degree of drawdown of the annular sheet 5 and the lens shape of the translucent strand of the obtained sheet (flattened state and contact length) were evaluated, and the results are shown in Table 2. The nozzle pressure and die swell were measured in the same manner as in Example 1, and the results are shown in Table 2. The projection screen thus obtained was combined with a Fresnel lens to form a transmissive screen, which was then attached to a color projection television for observation, but the viewing angle was narrow, the color balance was poor, and practical level optical characteristics were not obtained.

[0057]

[Table 2]

In Tables 1 and 2, the symbols of the respective components of the resin composition indicate the following compounds. PC-A: Linear polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd. Iupilon H3000) PC-B: Copolymerized polycarbonate resin (number average molecular weight = 18500) PC-C: Copolymerized polycarbonate resin (number average molecular weight = 25400) PC-D : Branched polycarbonate resin (Lexan 153 manufactured by Nippon GE Plastics) SBS: styrene-butadiene-styrene block copolymer (KR05 manufactured by Nippon Steel Chemical Co., butadiene content 2)
5% by weight) MSH: Cross-linked particles of styrene-methyl methacrylate copolymer (styrene / methyl methacrylate = 6/4, average particle size 5 μm) Incidentally, copolymerized polycarbonate resin (PC-B and P
C-C) has the structural units represented by the following general formulas (10) and (11) in a molar ratio of 9: 1.

[0059]

[Chemical 10]

[0060]

[Chemical 11]

[0061]

INDUSTRIAL APPLICABILITY The present invention provides a polycarbonate resin composition excellent in processability that enables extrusion molding with high processing accuracy as an extrusion molding material for a molded product having a complicated and fine shape, and at the same time shears the polycarbonate resin. It is possible to provide an optical sheet such as a projection screen, which can form a lens shape accurately without causing a decrease in viscosity and has excellent optical characteristics.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing a part of a projection screen which is an example of an optical sheet of the present invention.

2 is a schematic diagram of an apparatus used to manufacture the projection screen of FIG.

FIG. 3 is a schematic view of a nozzle used for manufacturing the projection screen of FIG.

4 is a schematic enlarged view showing a part of a nozzle used for manufacturing the projection screen of FIG. 1. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 translucent strand 2 light absorber 3 extruder 4 nozzle holder 5 annular sheet of translucent strand 6 annular guide 7 trowel-shaped guide 8 rod-shaped straight guide 9 nip roller 10 reel 11 nozzle 12 orifice for translucent strand 13 light Orifice for absorber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03B 21/62 // B29K 69:00

Claims (6)

[Claims] 1. A linear polycarbonate resin 20 to 95.
A polycarbonate resin composition comprising 80 to 99.5 wt% of a polycarbonate resin composed of 5 to 80 wt% of a branched polycarbonate resin and 0.5 to 20 wt% of a styrene resin. 2. The polycarbonate resin composition according to claim 1, wherein the styrene resin is a styrene-butadiene block copolymer. 3. A linear polycarbonate resin 20-95.
An optical sheet characterized by comprising 5% by weight of a branched polycarbonate resin and 5% by weight of a branched polycarbonate resin. 4. A polycarbonate resin 8 comprising a linear polycarbonate resin and a branched polycarbonate resin.
0 to 99.5% by weight and styrene resin 0.5 to 2
The optical sheet according to claim 3, comprising a resin composition containing 0% by weight. 5. The optical sheet according to claim 4, wherein the styrene resin is a styrene-butadiene block copolymer. 6. The optical element according to claim 3, wherein a plurality of light-transmissive plastic-based strands are arranged in parallel, and adjacent strands are joined and integrated into a sheet. Sheet.