KR20090091655A - Process for producing laminated resin sheet - Google Patents

Abstract

A method for manufacturing laminated resin plate is provided to suppress pigmentation and have shock resistance and scratch resistance. A method for manufacturing laminated resin comprises: a step (S1) of laminating a surface layer containing styrene based resin having 70 mass% of styrene based monomer; a step (S2) of performing separation a material by designing a part of circumference of laminated plate; and a step (S3,S4) of laminating the surface layer containing styrene based resin having 70 mass% of styrene based monomer.

Description

Manufacturing method of laminated resin plate {PROCESS FOR PRODUCING LAMINATED RESIN SHEET}

MEANS TO SOLVE THE PROBLEM This invention is a method of manufacturing a laminated resin plate by recycling using the single-piece (edge material) which arises at the time of manufacture, and can manufacture the laminated resin board excellent in impact resistance and abrasion resistance, while coloring is fully suppressed. It relates to a manufacturing method.

As a liquid crystal display device, what has a structure by which the surface light source device is arrange | positioned as a backlight on the back side of the liquid crystal panel (image display part) provided with a liquid crystal cell is known, for example. As the surface light source device for backlight, a surface light source device having a configuration in which a plurality of light sources are arranged in a lamp box (casing) and a light diffusion plate is arranged on the front side of these light sources is known.

The light diffusion plate is required to be excellent in impact resistance so as not to be damaged by contact during transportation or assembly. As a thing which can satisfy such a request, the light-diffusion plate which consists of polycarbonate resins is known (refer Unexamined-Japanese-Patent No. 2004-29091 (patent document 1)).

However, the light diffusing plate has a problem of being easily scratched because the exposed surface is a polycarbonate resin surface.

Therefore, as well as impact resistance and scratch resistance, a light diffusing plate formed by laminating a surface layer made of acrylic resin (for example, PMMA) on at least one side of a base layer made of a polycarbonate resin has been proposed (Japanese Patent Laid-Open No. 2005) -234521 (Patent Document 2).

By the way, in recent years, recycling of a resin material is calculated | required from a viewpoint of global environmental conservation. Therefore, in order to comply with this, the inventors conceived a manufacturing method of reusing a single material (edge material) produced when manufacturing a light diffusion plate as part of a material constituting a base layer.

However, in the case of adopting the structure of the latter light diffusion plate, if such a single material is reused and manufactured as part of the base layer, the base layer is a composition in which an acrylic resin is mixed with a polycarbonate resin, but the acrylic resin is mixed. There existed a problem that a light-diffusion plate turned into a slightly yellowish hue by containing.

This invention is made | formed in view of such a technical background, The manufacturing method which can manufacture the laminated resin board which can recycle and utilize the cutting material which arises at the time of manufacture, is fully suppressed, and is excellent in impact resistance and abrasion resistance. The purpose is to provide.

In order to achieve the above object, the present invention provides the following means.

[1] a lamination step of laminating a surface layer made of a styrene resin having a styrene monomer unit on at least one side of a base layer containing a polycarbonate resin to obtain a laminate;

Performing a process of cutting at least a part of the periphery of the laminate to separate the sheet as a sheet, thereby obtaining the sheet;

The manufacturing method of the laminated resin board which laminates the surface layer which contains the styrene-type resin which has 70 mass% or more of styrene-type monomeric units on the at least single side | surface of the base layer which consists of a resin composition obtained by mixing the said single material with polycarbonate resin.

[2] When the thickness of the base layer in the laminate is set within the range of 9 to 100 times the thickness of the surface layer, and the mixing of the cutting material with the polycarbonate resin, the cutting material is added to 100 parts by mass of the polycarbonate resin. The manufacturing method of the preceding paragraph which mixes 1-120 mass parts.

[3] a base layer comprising 0.1 to 10 parts by mass of a styrene resin having 70% by mass or more of a styrene monomer unit, based on 100 parts by mass of the polycarbonate resin;

It is provided with the surface layer which contains the styrene-type resin which has 70 mass% or more of styrene-type monomeric units integrated on the single side | surface or both surfaces of the said base layer,

The laminated resin plate whose thickness of the said base layer is 9 to 100 times the thickness of the said surface layer.

[4] The laminated resin plate according to the item 3, wherein the base layer contains 0.1 to 10 parts by mass of the styrene resin and 0.1 to 10 parts by mass of the light diffusing particles with respect to 100 parts by mass of the polycarbonate resin.

In the invention (manufacturing method) of [1], since the cutting material from a manufacturing process is reused as a part of the base material, it can contribute to the effective use of resources and contribute to global environmental preservation that is a social request. Moreover, since the laminated resin plate obtained by this manufacturing method is a structure which a base layer contains polycarbonate resin, it is excellent in impact resistance, and has a styrene resin which has 70 mass% or more of styrene-type monomer units in at least one side of a base layer. Since the surface layer which contains is laminated | stacked, it is excellent also in scratch resistance. In addition, since the polycarbonate resin has little coloring such as yellow, and the styrene resin also has little coloring such as yellow, even if the ratio of reuse of the cutting material as part of the constituent material of the base layer is increased (that is, the recycling content ratio of the cutting material is increased. Even if it increases, the laminated resin board (light diffuser board etc.) by which coloring, such as yellow, was fully suppressed, can be manufactured.

In the invention of [2], the thickness of the base layer in the laminated board is set within the range of 9 to 100 times the thickness of the surface layer, and 100 parts by mass of the polycarbonate resin is obtained when the base material is obtained by mixing the single material with the polycarbonate resin. Since 1-120 mass parts of single materials are mixed with respect to, laminated resin board (light diffuser board etc.) in which coloring, such as yellow, was suppressed more fully can be manufactured.

Invention of [3] corresponds to the preferable structure in the laminated resin board obtained by the manufacturing method of [1], and has a styrene resin which has a styrene-type monomeric unit 70 mass% or more with respect to 100 mass parts of polycarbonate resins. Since it is a structure which contains 0.1-10 mass parts of ethylene, it is excellent in impact resistance, and since the surface layer which contains the styrene resin which has 70 mass% or more of styrene-based monomeric units is laminated | stacked on at least one side of a base layer, The castle is also excellent. Moreover, since polycarbonate resin has little coloring, such as yellow, the said styrene resin also has little coloring, such as yellow, and since the thickness of the thickness / surface layer of a base layer is set in the range of 9-100, since coloring, such as yellow, The laminated resin plate suppressed sufficiently is provided.

In the invention of [4], although the base layer is the structure which further contains light-diffusion particle, even if it is the structure which contains such light-diffusion particle | grains, coloring of yellow etc. is fully suppressed. That is, in the case where the light diffusion particles are present in the base layer, the length of the optical path passing through the laminated resin plate becomes long, so that the coloring becomes more noticeable particularly easily as compared with the case where the light diffusion particles do not exist. In the present invention, even when light diffusing particles are present in the base layer, coloring such as yellow is sufficiently suppressed. That is, even if it contains light-diffusion particle | grains in a base layer, the light-diffusion laminated resin board in which coloring, such as yellow, was fully suppressed is provided.

According to this invention, while being able to recycle and use the cutting material which arises at the time of manufacture, coloring resin is fully suppressed and the laminated resin board excellent in impact resistance and abrasion resistance can be manufactured.

The manufacturing method of the laminated resin plate which concerns on this invention is demonstrated, referring FIGS. In addition, in the following description and FIG. 2, a "step" is abbreviated as "S".

First, the laminated board 3 is obtained by laminating | stacking the surface layer 9 containing styrene-type resin which has 70 mass% or more of styrene-type monomeric units on at least one side of the base layer 8 containing polycarbonate resin (S1). ). In this embodiment, the surface layer 9 (9) is laminated | stacked on both surfaces of the base layer 8, and the laminated board 3 is obtained (refer FIG. 1). Here, as the base layer 8, preferably obtained by melt molding a thermoplastic resin, using only a polycarbonate resin as the thermoplastic resin to melt, or 100 parts by mass of the polycarbonate resin and 70% by mass or more of the styrene monomer unit It is a layer obtained using 0.1-10 mass parts of styrene resin which has. Moreover, as said surface layer 9, Preferably it is a layer which consists of the said styrene resin.

Next, at least a part of the periphery of the obtained laminated sheet 3 is cut to obtain a product (laminated resin sheet) of a predetermined size, and the cut portion is separated as a single cutting material (S2).

Since the laminated resin plate obtained in this way is a structure which the base layer 8 contains a polycarbonate resin, it is excellent in impact resistance, and has a styrene system which has 70 mass% or more of styrene-based monomer units on at least one side of the base layer 8. Since the surface layer 9 containing resin is laminated, the scratch resistance is also excellent.

Next, the base material resin is prepared by mixing the single material with the polycarbonate resin (S3). At this time, it is preferable to mix 1-120 mass parts of single materials with respect to 100 mass parts of polycarbonate resin, and to prepare the composition of resin for base layers.

Then, the laminated board 3 is obtained by laminating | stacking the surface layer 9 which consists of styrene resin which has 70 mass% or more of styrene-type monomeric units on the single side | surface or both surfaces of the base layer 8 which consists of said base material resin ( S4).

Next, at least a part of the periphery of the obtained laminated sheet 3 is cut to obtain a product (laminated resin sheet) of a predetermined size, and the cut portion is separated as a single cutting material (S5).

Since the laminated resin plate obtained in this way is a structure which the base layer 8 contains a polycarbonate resin, it is excellent in impact resistance, and has a styrene system which has 70 mass% or more of styrene-based monomeric units on at least one side of the base layer 8. Since the surface layer 9 containing resin is laminated, the scratch resistance is also excellent. In addition, since the polycarbonate resin has little coloring such as yellow, styrene-based resin having 70% by mass or more of styrene-based monomer units, less coloring such as yellow, and less coloring due to the mixed content thereof. In spite of being reused as part of the constituent material), it is possible to produce a laminated resin plate in which coloring such as yellow is sufficiently suppressed. Moreover, even if the ratio of reusing the cutting material as part of the constituent material of the base layer 8 is increased (that is, even if the recycling content ratio of the cutting material is increased), coloring such as yellow can be sufficiently suppressed.

Thus, although the said laminated resin plate obtained through S3 and S4 was manufactured by providing a single piece for reuse once (refer FIG. 2), in the manufacturing method of this invention, the following process is further performed to give a laminated resin plate. You may make it.

That is, the base material resin is prepared by mixing the said cutting material which came out in the cutting process of S5 with polycarbonate resin (S6). Under the present circumstances, it is preferable to mix 1-120 mass parts of cutting materials with respect to 100 mass parts of polycarbonate resin, and to prepare the composition of base resin.

Then, the laminated board 3 is obtained by laminating | stacking the surface layer 9 containing styrene-type resin which has 70 mass% or more of styrene-type monomeric units on the single side | surface or both surfaces of the base layer 8 which consists of said base material resin ( S7).

Next, at least a part of the periphery of the obtained laminated sheet 3 is cut to obtain a product (laminated resin sheet) of a predetermined size, and the cut portion is separated as a single cutting material (S8).

Since the laminated resin plate obtained in this way is a structure comprised from the base layer 8 containing polycarbonate resin similarly to the above, it is excellent in impact resistance, and has 70 mass of styrene-based monomeric units on at least one side of the base layer 8. Since the surface layer 9 containing the styrene resin which has% or more is laminated | stacked, it is excellent also in scratch resistance. In addition, the cutting material recycled in S6 is a mixture of the cutting material recycled in previous S3 in the base layer, so that it is provided for the 2nd reuse, so that the said styrene system in the composition of base resin obtained in S6 is obtained. Although the content rate of resin is increased than the content rate of the said styrene resin in the composition of base resin obtained by S3 previously, here, the styrene resin which has 70 mass% or more of styrene-type monomer units has little coloring, such as yellow. Therefore, it is possible to obtain a laminated resin plate whose coloring is sufficiently suppressed.

Next, the base material resin is prepared by mixing the single material with the polycarbonate resin (S9). It is preferable to prepare the composition of resin for base layers by mixing 1-120 mass parts of cutting materials with respect to 100 mass parts of polycarbonate resins similarly to the above.

Hereinafter, by repeating S7 to S9 sequentially in the same manner, a laminated resin plate excellent in impact resistance and scratch resistance can be produced while coloring of yellow and the like is sufficiently suppressed while reusing the cutting material produced in the manufacturing process. That is, the recycling content ratio of the cutting material in the laminated resin plate obtained increases little by little by providing the cutting material for reuse twice, three times, or four times or more. As described above, the polycarbonate resin may be yellow or the like. Since the coloration is small, the styrene-based resin having 70% by mass or more of the styrene-based monomer unit is less colored, such as yellow, and the coloring is less by the mixed content thereof. This sufficiently suppressed laminated resin plate can be obtained. As described above, in the present production method, coloration such as yellow can be suppressed not only when single cutting is provided for reuse but also when the single cutting is used for reuse a plurality of times, so the present manufacturing method is suitable for industrial production.

The method of laminating the base layer 8 and the surface layer 9 is not particularly limited, but for example, a coextrusion molding method, an adhesion method, a thermal adhesion method, a solvent adhesion method, a polymerization adhesion method, a cast polymerization method And surface coating methods. Among them, a coextrusion molding method is preferable in which work is easy, manufacturing efficiency is high, and there is no need to use other materials such as an adhesive.

Moreover, when mixing the said single material with a polycarbonate resin, even if it is a defect, a contamination, a crack, etc. exist, the quality defective article (the poor quality laminated resin board) which cannot provide as a product may be mixed with the said polycarbonate resin with polycarbonate resin. do.

In this invention, styrene resin which has 70 mass% or more of styrene-type monomeric units is used as styrene resin which comprises the said surface layer 9. When the content rate of the styrene monomer unit is less than 70% by mass, there is a fear that the scratch resistance is not sufficiently obtained, and coloring such as yellow becomes noticeable. Especially, as styrene resin which comprises the said surface layer 9, it is preferable to use styrene resin which has 75 mass% or more of styrene monomer units.

As such a styrene resin, the homopolymer of styrene may be sufficient, and the copolymer of the monomer and styrene which can be copolymerized with styrene may be sufficient as it. As a monomer copolymerizable with styrene, methacrylic acid ester, such as methyl methacrylate and butyl methacrylate, acrylic acid ester, such as methyl acrylate and butyl acrylate, etc. are mentioned, Methacrylic acid ester is preferable, and Among these, methyl methacrylate is preferable.

Although it does not specifically limit as said styrene resin, For example, methyl methacrylate-styrene copolymer (content of methyl methacrylate unit: 20 mass%, content of styrene unit: 80 mass%), polystyrene, etc. Can be mentioned.

In addition, the base layer 8 may contain light diffusing particles. In this case, it becomes a preferable thing as a light-diffusion plate. As said light-diffusion particle | grains, it is a particle | grains from which refractive index differs from resin or mixed resin which comprises the said base layer 8, and can disperse | distribute the light which permeate | transmits the laminated resin board (light diffuser plate) by disperse | distributing and containing the particle | grains. If it is, it will not specifically limit. For example, inorganic particles such as glass particles, glass fibers, silica particles, aluminum hydroxide particles, calcium carbonate particles, barium sulfate particles, titanium oxide particles, and talc may be used, and styrene polymer particles, acrylic polymer particles, and siloxane polymer particles. Organic particles, such as these, may be sufficient.

Moreover, in the said base layer 8, additives, such as a ultraviolet absorber, a heat stabilizer, antioxidant, a weathering agent, a light stabilizer, a fluorescent brightener, a processing stabilizer, a nucleating agent, are contained in the range which does not impair the effect of this invention. You can also do it.

Similarly, in the range which does not impair the effect of this invention, the said surface layer 9 contains additives, such as a ultraviolet absorber, a heat stabilizer, antioxidant, a weathering agent, a light stabilizer, a fluorescent brightener, a processing stabilizer, a nucleating agent, etc. You can also do it.

Thickness R of the said base layer 8 is 500-2990 micrometers normally. Sufficient impact resistance can be ensured by being 500 micrometers or more, and cost increase can be suppressed by being 2990 micrometers or less. Especially, thickness R of the said base layer 8 becomes like this. Preferably it is 700 micrometers or more, 2980 micrometers or less, More preferably, it is 2500 micrometers or less.

Moreover, the thickness T of the said surface layer 9 is 10-300 micrometers normally. While sufficient scratch resistance is obtained by being 10 micrometers or more, cost increase can be suppressed by being 300 micrometers or less. Especially, thickness T of the said surface layer 9 becomes like this. Preferably it is 20 micrometers or more and 200 micrometers or less.

It is preferable that the thickness of the said base layer is set to 9-100 times the thickness of the said surface layer. Enough impact resistance can be ensured by being 9 or more, and sufficient scratch resistance can be ensured by being 100 or less. Especially, it is more preferable that the thickness of the said base layer is set to 10 to 80 times the thickness of the said surface layer. In addition, the thickness of the laminated resin plate is usually set in the range of 0.51 mm to 3.29 mm, preferably 1 to 3 mm.

In addition, in the said embodiment, although the structure which laminated | stacked and integrated the surface layer 9 and 9 on both surfaces of the base layer 8 was employ | adopted (refer FIG. 1), it is not specifically limited to such a structure, The base layer 8 A structure in which the surface layer 9 is laminated and integrated on one side thereof may be employed. However, it is preferable to employ | adopt the structure which laminated | stacked and integrated the surface layer 9 and 9 on both surfaces of the base layer 8 like the said embodiment from the point which can fully prevent curvature.

The preferable structure as a laminated resin plate obtained by the manufacturing method of this invention is the base layer 8 which consists of 0.1-10 mass parts of styrene resins which have 100 mass parts of polycarbonate resins, and 70 mass% or more of styrene monomer units, and the said base layer A structure having a surface layer 9 made of a styrene-based resin having a styrene-based monomer unit of at least 70 mass% and integrally laminated on one or both surfaces thereof, wherein the thickness of the base layer is set to be 9 to 100 times the thickness of the surface layer. to be. The laminated resin plate which consists of such a structure is excellent in impact resistance and abrasion resistance, while coloring is fully suppressed.

In addition, the manufacturing method of the laminated resin plate which concerns on this invention is not specifically limited to the thing of embodiment illustrated above, If it is in a Claim, any design change is permissible, unless it deviates from the mind.

(Example)

Next, although the specific Example of this invention is described, this invention is not specifically limited to the thing of these Examples.

<Example 1>

Methyl methacrylate-styrene copolymer (content of methyl methacrylate unit: about 20 mass%, content of styrene unit: about 80 mass%) ("MS200" manufactured by Shin-Nitetsu Chemical Co., Ltd.) 78.55 parts by mass, acrylic polymer particles (crosslinking Polymer particles) (Sumipex XC1A manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter about 25 μm) The resin composition A for surface layer formation was obtained by dry-blending 0.20 mass part of Sumitomo Chemical Co., Ltd., and 0.25 mass part of monogly D (molding agent, the Nippon Oil Holdings company).

The resin composition A for surface layer formation was fed to a second extruder having a screw diameter of 20 mm, melt kneaded at 250 ° C, and fed to a multi-manifold die.

On the other hand, 100 mass parts of polycarbonate resin ("Kariba PC200-30" by Sumitomo Dowsa), 1.0 mass part of said resin composition A for surface layer formation, siloxane-type polymer particle (light-diffusion particle) ("Trew Dow Corning company" tre DY33-719 ", volume average particle diameter 2 micrometers) 0.2 mass parts was dry-blended, it was supplied to the 1st extruder of screw diameter 40mm, melt-kneaded at 250 degreeC, and it was supplied to the multi-manifold die.

Temperature 245-250 so that the resin composition supplied from the said 1st extruder to a multi-manifold die will be a base layer 8, and the resin composition supplied from the said 2nd extruder to a multi-manifold die will be a surface layer (9) (9). Coextrusion was performed at degreeC, and the light-diffusion plate which consists of three laminated boards 3 of thickness 2.0mm (base layer 1.9mm, surface layer 0.05mm * 2) shown in FIG. 1 was manufactured.

<Examples 2-4>

A light diffusing plate was produced in the same manner as in Example 1 except that the content ratio of each component in the resin composition (for the base layer) supplied to the first extruder and the thickness of each layer were set under the conditions shown in Table 1, respectively. It was.

<Example 5>

Polystyrene (content of styrene unit: 100 mass%) (78.55 parts by mass of Toyo Styrene Co., Ltd.), acrylic polymer particles (crosslinked polymer particles) 20.00 parts by mass, adecas top LA31 (benzotriazole-based ultraviolet absorber, manufactured by ADEKA) 1.00 parts by mass, Smizerizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.20 parts by mass, Monogly D (molding agent, manufactured by Nippon Oil Industries, Ltd.) ) 0.25 mass parts was dry blended to obtain a resin composition B for forming a surface layer.

The said resin composition B for surface layer formation was supplied to the 2nd extruder of screw diameter 20mm, it was melt-kneaded at 250 degreeC, and was supplied to the multi manifold die.

On the other hand, 100 mass parts of polycarbonate resin ("Kariba PC200-30" by Sumitomo Dowsa), 1.0 mass part of said resin composition B for surface layer formation, siloxane type polymer particle (light-diffusion particle) (Trew Dow Corning Corporation "tre DY33-719 ", volume average particle diameter 2 micrometers) 0.2 mass parts was dry-blended, it was supplied to the 1st extruder of screw diameter 40mm, melt-kneaded at 250 degreeC, and it was supplied to the multi-manifold die.

Temperature 245-250 so that the resin composition supplied from the said 1st extruder to a multi-manifold die will be a base layer 8, and the resin composition supplied from the said 2nd extruder to a multi-manifold die will be a surface layer (9) (9). Coextrusion was performed at degreeC, and the light-diffusion plate which consists of three laminated boards 3 of thickness 2.2mm (base layer 2.1mm, surface layer 0.05mmx2) shown in FIG. 1 was manufactured.

<Examples 6 to 8>

A light diffusing plate was produced in the same manner as in Example 5 except that the content ratio of each component in the resin composition (for the base layer) to be supplied to the first extruder and the thickness of each layer were set under the conditions shown in Table 1, respectively. It was.

Comparative Example 1

Acrylic resin (content of methyl methacrylate unit: 90 mass% or more) (MG5, manufactured by Sumitomo Chemical Co., Ltd.) 78.55 parts by mass, acrylic polymer particles (crosslinked polymer particles) (Sumipex XC1A, manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter 25 µm) 20.00 parts by mass, Adecas Top LA31 (benzotriazole UV absorber, manufactured by ADEKA) 1.00 parts by mass, Smizer GP (process stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.20 parts by mass, Monogly D (molding agent, The resin composition C for surface layer formation was obtained by carrying out dry blending 0.25 mass parts of Nippon Oil-Patent Company.

The resin composition C for surface layer formation was fed to a second extruder having a screw diameter of 20 mm, melt kneaded at 250 ° C, and fed to a multi-manifold die.

On the other hand, 100 parts by mass of polycarbonate resin ("Kariba PC200-30" manufactured by Sumitomo Dowsa), 1.0 parts by mass of the resin composition C for surface layer formation, siloxane-based polymer particles (light diffusing particles) ("Trew Dow Corning" Tre DY33-719 ", volume average particle diameter 2 micrometers) 0.2 mass parts was dry-blended, it was supplied to the 1st extruder of screw diameter 40mm, melt-kneaded at 250 degreeC, and it was supplied to the multi-manifold die.

Temperature 245-250 so that the resin composition supplied from the said 1st extruder to a multi-manifold die will be a base layer 8, and the resin composition supplied from the said 2nd extruder to a multi-manifold die will be a surface layer (9) (9). Coextrusion was performed at degreeC, and the light-diffusion plate which consists of three laminated boards 3 of thickness 2.0mm (base layer 1.9mm, surface layer 0.05mm * 2) shown in FIG. 1 was manufactured.

<Comparative Examples 2-4>

A light diffusing plate was produced in the same manner as in Comparative Example 1 except that the content ratio of each component in the resin composition (for the base layer) to be supplied to the first extruder and the thickness of each layer were set under the conditions shown in Table 2, respectively. It was.

Comparative Example 5

Methyl methacrylate-styrene copolymer (content of methyl methacrylate unit: about 50 mass%, content of styrene unit: about 50 mass%) ("MM50" made by Nippon A & L) 78.55 parts by mass, acrylic polymer particles (crosslinking Polymer particles) (Sumipex XC1A manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter about 25 μm) And 0.20 parts by mass of Sumitomo Chemical Co., Ltd. and 0.25 parts by mass of Monogly D (molding agent, manufactured by Nippon Oil Industries, Ltd.) were obtained by dry blending to obtain a resin composition D for forming a surface layer.

The resin composition D for forming the surface layer was fed to a second extruder having a screw diameter of 20 mm, melt kneaded at 250 ° C, and fed to a multi-manifold die.

On the other hand, 100 parts by mass of polycarbonate resin ("Kariba PC200-30" manufactured by Sumitomo Dowsa), 2.4 parts by mass of the resin composition D for surface layer formation, and siloxane polymer particles (light diffusing particles) ("Tre Dow Corning" Tre DY33-719 ", and 0.2 mass parts of volume average particle diameters were dry-blended, it was supplied to the 1st extruder of screw diameter 40mm, melt-kneaded at 250 degreeC, and was supplied to the multi manifold die.

Temperature 245-250 so that the resin composition supplied from the said 1st extruder to a multi-manifold die will be a base layer 8, and the resin composition supplied from the said 2nd extruder to a multi-manifold die will be a surface layer (9) (9). Coextrusion was performed at degreeC, and the light-diffusion plate which consists of three laminated boards 3 of thickness 2.0mm (base layer 1.9mm, surface layer 0.05mm * 2) shown in FIG. 1 was manufactured.

<Comparative Examples 6 and 7>

A light diffusing plate was manufactured in the same manner as in Comparative Example 5 except that the content ratio of each component in the resin composition (for the base layer) to be supplied to the first extruder and the thickness of each layer were set under the conditions shown in Table 2, respectively. It was.

Each light diffuser plate obtained as described above was evaluated according to the following evaluation method. The evaluation results are shown in Tables 1 and 2.

<All-light transmittance measuring method>

The total light transmittance (%) of the light diffusion plate was measured in accordance with JIS K7361-1997.

<Diffusion Light Transmittance Measurement Method>

The diffused light transmittance (%) of the light diffuser plate was measured in accordance with JIS K7136-2000.

<Haze value measuring method>

The haze value (%) of the light diffusion plate was measured in accordance with JIS K7136-2000.

<Measuring method of yellowness (YI) by spectroscopic transmittance measurement>

Using a magnetic spectrophotometer equipped with an integrating sphere ("UV-4000" manufactured by Hitachi, Ltd.), the spectral transmittance in the wavelength range of 380 to 780 nm of the light diffusion plate was measured, and the yellowness (YI) was calculated based on this. It was.

<Measurement of diffusion rate>

The intensity of the transmitted light with respect to the angle of 5 ° with respect to the normal direction among the transmitted light when the light is incident from the normal direction to the light diffusion plate using an automatic variable photometer (GP-IR, manufactured by Murakami Color Technology Research Institute). I ₅ , the intensity of transmitted light at an angle of 20 ° with respect to the normal direction I ₂₀ , the intensity of the transmitted light at an angle of 70 ° with respect to the normal direction, I ₇₀ , respectively,

D = 100 × (I ₂₀ + I ₇₀ ) / (2 × I ₅ )

Diffusion rate (D) (%) was calculated | required by the said calculation formula.

As is apparent from the table, the light diffusion plates of Examples 1 to 8 produced by the production method of the present invention have a small yellowness (YI) and are sufficiently suppressed in coloring. That is, even if the mixing ratio of the resin composition for surface layer formation in a base material increases, for example, as is clear from the contrast of the YI value of Example 1 and Example 4, and the contrast of the YI value of Example 5 and Example 8. (I.e., even if the recycle content rate of a cutting material increases) Yellowness (YI) was suppressed small. Moreover, in the light-diffusion plates of these Examples, even if the mixing ratio of the resin composition for surface layer formation in a base layer increases (that is, even if the recycle content rate of a single material increases), the total light transmittance and the diffused light transmittance are almost all unchanged. It was a constant level.

In the manufacturing method of this invention, when a single cutting material is provided for reuse multiple times, the recycle content rate of the cutting material in a laminated resin board increases little by little every time the reuse of single cutting material is repeated, but also in such a case, it is yellow. Fig. (YI) is suppressed small, and the total light transmittance and the diffuse light transmittance are almost all unchanged. Therefore, by adopting the production method of the present invention, it is possible to manufacture a laminated resin plate with stable quality while reusing a single material.

On the other hand, in the light-diffusion plates of Comparative Examples 1-7, yellowness (YI) was comparatively large and there existed slightly yellowish coloring. In addition, as apparent from the comparison of the YI values of Comparative Example 1 and Comparative Example 4 and the YI values of Comparative Example 5 and Comparative Example 7, the mixing ratio of the resin composition for forming the surface layer in the base layer is increased. (I.e., when the recycle content ratio of the cutting material was increased), the yellowness (YI) was relatively increased, and yellow coloring became noticeable. Moreover, when the mixing ratio of the resin composition for surface layer formation in a base layer increased (that is, when the recycle content rate of a single material increased), all the total light transmittance and the diffused light transmittance fell.

In the manufacturing method of this invention, since the cutting material from a manufacturing process is reused as a part of base material, it can contribute to the effective use of a resource and contribute to global environmental conservation which is a social request. Moreover, since the laminated resin plate obtained by this manufacturing method is a structure which a base layer contains polycarbonate resin, it is excellent in impact resistance, and has a styrene resin which has 70 mass% or more of styrene-based monomer units in at least one side of a base layer. Since the surface layer which contains is laminated | stacked, it is excellent also in scratch resistance. In addition, since the polycarbonate resin has little coloring such as yellow and the styrene-based resin also has little coloring such as yellow, even if the ratio of reuse of the cutting material as part of the constituent material of the base layer is increased (that is, the recycling content ratio of the cutting material is increased. Even if it increases, the laminated resin board (light diffuser board etc.) by which coloring, such as yellow, was fully suppressed, can be manufactured.

Although the light diffuser plate manufactured by the manufacturing method of this invention is used suitably as the light diffuser plate for surface light source devices used, for example as a backlight for liquid crystal display devices, it is not specifically limited to such a use.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one Embodiment of the laminated resin board which concerns on this invention.

2 is a flowchart showing an outline of an example of the manufacturing method of the present invention.

* Description of the symbols for the main parts of the drawings *

3: laminated plate (light diffuser plate)

8: substrate

9: surface layer

R: thickness of substrate

T: thickness of the surface layer

Claims (4)

A lamination step of laminating a surface layer made of a styrene resin having a styrene-based monomer unit on at least one side of the base layer containing a polycarbonate resin to obtain a laminate; Performing a process of cutting at least a part of the periphery of the laminate to separate the sheet as a sheet, thereby obtaining the sheet; The manufacturing method of the laminated resin board which laminates the surface layer which contains the styrene-type resin which has 70 mass% or more of styrene-type monomeric units on the at least single side | surface of the base layer which consists of a resin composition obtained by mixing the said single material with polycarbonate resin. The method of claim 1, While setting the thickness of the base layer in the laminated board to a range of 9 to 100 times the thickness of the surface layer, and mixing the cutting material with the polycarbonate resin, the cutting material is 1 to 120 to 100 parts by mass of the polycarbonate resin. The manufacturing method which mixes a mass part. Base layer which contains 0.1-10 mass parts of styrene resin which has 70 mass% or more of styrene-type monomeric units with respect to 100 mass parts of polycarbonate resins, It comprises a surface layer which contains the styrene resin which has 70 mass% or more of styrene-type monomer units integrally laminated on the single side | surface or both surfaces of the said base layer, The laminated resin plate whose thickness of the said base layer is 9 to 100 times the thickness of the said surface layer. The method of claim 3, wherein The base layer is a laminated resin plate containing 0.1 to 10 parts by mass of the styrene resin and 0.1 to 10 parts by mass of light-diffusing particles with respect to 100 parts by mass of the polycarbonate resin.

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