JP2011079167A - Method for producing laminated resin plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method which can recycle an end material produced during production and can produce a laminated resin plate with coloring suppressed enough. <P>SOLUTION: The manufacturing method includes an end material obtaining process in which after a laminated plate is obtained by laminating a surface layer containing a transparent resin (B) on at least one side of a base layer containing a transparent resin (A), at least one part of the peripheral part of the laminated plate is cut to classify it as the end material and a process for producing the laminated resin plate by laminating the surface layer containing the transparent resin (B) on at least one side of the base layer made of a resin composition obtained by mixing the transparent resin (A) with the end material or the end material. When the absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is (Δδ), and the absolute value of the difference between the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) is (Δn), the relational expression: Δδ×Δn≤0.42 is set up. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a manufacturing method for manufacturing a laminated resin plate in which coloring is sufficiently suppressed while recycling end materials (ear materials) that are produced during manufacturing.

  In this specification, the term “SP value” means Hansen's solubility parameter (Solubility Parameter).

  As a liquid crystal display device, for example, a configuration in which a surface light source device is disposed as a backlight on the back side of a liquid crystal panel (image display unit) including a liquid crystal cell is known. As the surface light source device for the backlight, a surface light source device having a configuration in which a plurality of light sources are disposed in a lamp box (housing) and a light diffusion plate is disposed on the front side of these light sources is known. .

  As the light diffusion plate, a multilayer light diffusion plate is known in which a surface layer containing a styrene-methyl methacrylate copolymer and an ultraviolet absorber is laminated on a base layer made of polystyrene (see Patent Document 1). By laminating such a surface layer, deterioration due to ultraviolet rays can be prevented. As described above, since the light diffusing plate is required to have various characteristics in addition to the light diffusing performance depending on the application, it is different from the resin constituting the base layer on at least one side of the base layer. A laminated board in which surface layers made of resin are laminated is often used.

JP 2008-292977 A

  By the way, in recent years, from the viewpoint of global environmental conservation, it has been required to recycle resin materials. In view of this, the present inventor has conceived a manufacturing method in which the end material (ear material) that is produced when the light diffusing plate is manufactured is reused as part of the material constituting the base layer.

  However, in the case of employing the above-described conventional laminated structure, for example, when polystyrene is used for the base layer and a styrene-methyl methacrylate copolymer (styrene unit 40% by mass, methyl methacrylate unit 60% by mass) is used for the surface layer. When such a milled material is reused and manufactured as a part of the base layer, polystyrene is mixed with styrene-methyl methacrylate copolymer (styrene unit 40% by mass, methyl methacrylate unit 60% by mass) as the base layer. However, such a mixed composition has a problem that the light diffusion plate has a slightly yellowish hue.

  The present invention has been made in view of such a technical background, and can be used to recycle offcuts produced at the time of manufacture, and a manufacturing method capable of manufacturing a laminated resin plate in which coloring is sufficiently suppressed. The purpose is to provide.

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

[1] After obtaining a laminated board by laminating a surface layer containing a transparent resin (B) on at least one side of a base layer containing the transparent resin (A), at least the peripheral part of the laminated board A scrap material acquisition process in which a part is cut and separated as a scrap material;
A surface layer containing a transparent resin (B) is laminated on at least one side of a base layer made of a resin composition obtained by mixing the transparent resin (A) and the end material or made of the end material. A step of manufacturing a resin plate,
The absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) A manufacturing method of a laminated resin plate, wherein a relational expression of Δδ × Δn ≦ 0.42 is satisfied when an absolute value of the difference is “Δn”.

[2] After laminating the surface layer containing the transparent resin (B) on at least one side of the base layer containing the transparent resin (A) to obtain the first laminated plate, A first edge material acquisition step of cutting at least a part of the peripheral edge and separating it as a first edge material;
A surface layer comprising a transparent resin (B) on at least one side of a base layer comprising a resin composition obtained by mixing a transparent resin (A) and the first end material or comprising the first end material. After obtaining the second laminate by laminating, a second end material acquisition step of cutting at least a part of the peripheral edge of the second laminate and separating it as a second end material;
A surface layer comprising a transparent resin (B) on at least one surface of a base layer comprising a resin composition obtained by mixing the transparent resin (A) and the second end material or comprising the second end material. And laminating to produce a laminated resin plate,
The absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) A manufacturing method of a laminated resin plate, wherein a relational expression of Δδ × Δn ≦ 0.42 is satisfied when an absolute value of the difference is “Δn”.

  [3] When the thickness of the base layer in the laminate is set in the range of 9 to 100 times the thickness of the surface layer, the transparent resin (A) is mixed with the transparent resin (A) and the end material. 3. The method for producing a laminated resin plate according to item 1 or 2, wherein mixing is performed so that the content of the end material relative to the total amount of the end material is 1% by mass or more and less than 100% by mass.

  [4] The method for producing a laminated resin sheet according to any one of items 1 to 3, wherein a relational expression of 0.03 ≦ Δn ≦ 0.15 is established.

  [5] The method for producing a laminated resin plate according to any one of the above items 1 to 4, wherein the transparent resin (A) is a styrene resin, and the transparent resin (B) is a styrene resin or an acrylic resin. .

[6] A base layer containing 0.01 to 20 parts by mass of the transparent resin (B) with respect to 100 parts by mass of the transparent resin (A);
A surface layer containing a transparent resin (B) that is laminated and integrated on one or both sides of the base layer, and
The thickness of the base layer is in the range of 9 to 100 times the thickness of the surface layer;
The absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) A laminated resin plate characterized in that a relational expression of Δδ × Δn ≦ 0.42 holds when an absolute value of the difference is “Δn”.

  [7] The preceding item, wherein the base layer contains 0.01 to 20 parts by mass of the transparent resin (B) and 0.01 to 10 parts by mass of light diffusing particles with respect to 100 parts by mass of the transparent resin (A). 6. The laminated resin plate according to 6.

  [8] The laminated resin plate according to item 6 or 7, wherein the transparent resin (A) is a styrene resin, and the transparent resin (B) is a styrene resin or an acrylic resin.

  [9] A surface light source device comprising: a light diffusing plate comprising the laminated resin plate according to any one of 6 to 8 above; and a plurality of light sources arranged on the back side of the light diffusing plate. .

  [10] A light diffusing plate comprising the laminated resin plate according to any one of 6 to 8 above, a plurality of light sources arranged on the back side of the light diffusing plate, and arranged on the front side of the light diffusing plate A liquid crystal display device comprising: a liquid crystal panel.

  In the inventions [1] and [2] (manufacturing method), the scraps produced in the manufacturing process are reused as a part of the constituent material of the base layer, which leads to effective use of resources and the preservation of the global environment as a social request Can contribute. The absolute value of the difference between the SP value of the transparent resin (A) and the transparent resin (B) is “Δδ”, and the difference between the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) When the absolute value is “Δn”, the relational expression of Δδ × Δn ≦ 0.42 is established. Therefore, even if the ratio of recycling the end material as a part of the constituent material of the base layer is increased (that is, Even if the recycled content ratio of the mill ends is increased), a laminated resin plate (light diffusion plate or the like) in which coloring such as yellow is sufficiently suppressed can be produced.

  In the invention of [3], when the thickness of the base layer in the laminate is set in the range of 9 to 100 times the thickness of the surface layer, and the end material is mixed with the transparent resin (A) to obtain the base layer material In addition, since the mixing ratio is such that the content of the end material relative to the total amount of the transparent resin (A) and the end material is 1% by mass or more and less than 100% by mass, the laminated resin plate in which coloring such as yellow is more sufficiently suppressed (Such as a light diffusion plate) can be manufactured.

  In the invention of [4], the relational expression of 0.03 ≦ Δn ≦ 0.15 is established, but such a difference in refractive index between the transparent resin (A) and the transparent resin (B) is large. However, a laminated resin plate (such as a light diffusing plate) in which coloring such as yellow is sufficiently suppressed can be manufactured (because the relational expression of Δδ × Δn ≦ 0.42 is satisfied).

  In the invention of [5], since the transparent resin (A) is a styrene resin and the transparent resin (B) is a styrene resin or an acrylic resin, a laminated resin plate in which coloring such as yellow is more sufficiently suppressed. (Such as a light diffusion plate) can be manufactured.

  The invention of [6] corresponds to a preferred configuration among the laminated resin plates obtained by the production methods of [1] to [5], and the base layer is a transparent resin with respect to 100 parts by mass of the transparent resin (A). It is the structure formed by containing 0.01-20 mass parts of (B), the surface layer containing transparent resin (B) is laminated | stacked on the at least single side | surface of a base layer, and the thickness of a base layer is the thickness of a surface layer. Is set in the range of 9 to 100 times, and a relational expression of Δδ × Δn ≦ 0.42 is established, so that a laminated resin plate in which coloring such as yellow is sufficiently suppressed is provided.

  In the invention of [7], the base layer further comprises a light diffusing particle, but coloring such as yellow was sufficiently suppressed even in a constitution comprising such a light diffusing particle. It will be a thing. That is, when the light diffusing particles are present in the base layer, the optical path length passing through the laminated resin plate is increased, so that coloring is usually particularly noticeable as compared with the case where no light diffusing particles are present. However, in the present invention, even when light diffusing particles are present in the base layer, coloring such as yellow is sufficiently suppressed. That is, there is provided a light diffusing laminated resin plate in which coloring such as yellow is sufficiently suppressed even though the base layer contains light diffusing particles.

  In the invention of [8], since the transparent resin (A) is a styrene resin and the transparent resin (B) is a styrene resin or an acrylic resin, a laminated resin plate in which coloring such as yellow is more sufficiently suppressed. (Such as a light diffusing plate).

  In the invention of [9], it is possible to emit diffused light having high whiteness that is not substantially yellowish.

  In the invention of [10], a liquid crystal display device capable of realizing a natural and high-quality color display without being yellowish is provided.

It is sectional drawing which shows one Embodiment of the laminated resin board which concerns on this invention. It is a flowchart which shows the outline of an example of the manufacturing method of this invention.

  A method for manufacturing a laminated resin plate according to the present invention will be described with reference to FIGS. In the following description and FIG. 2, “step” is abbreviated as “S”.

  First, a surface layer (9) containing a transparent resin (B) is laminated on at least one surface of a base layer (8) containing a transparent resin (A) to obtain a first laminate (3) ( S1). In this embodiment, surface layers (9) and (9) are laminated on both sides of the base layer (8) to obtain a first laminated plate (3) (see FIG. 1).

Here, as the transparent resin (A) and the transparent resin (B), those satisfying the following formula (1) are used. That is, the absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refraction of the transparent resin (B) are set. When the absolute value of the rate difference is “Δn”,
Δδ × Δn ≦ 0.42 (1)
The transparent resin (A) and the transparent resin (B) that are in a relationship that satisfies the above formula (1) are used.

  Next, at least a part of the peripheral portion of the obtained first laminated plate is cut to obtain a product (first laminated resin plate) (3) having a predetermined size, and the cut portion is used as the first end material. (S2). S1 and S2 are the first edge material acquisition process.

  The first laminated resin plate (3) thus obtained has surface layers (9) and (9) containing the transparent resin (B) on both sides of the base layer (8) containing the transparent resin (A). It is a laminated structure.

  Next, a base layer resin is prepared by mixing the first end material with the transparent resin (A) (S3). At this time, the composition of the resin for the base layer is prepared by mixing so that the content of the first end material relative to the total amount of the transparent resin (A) and the first end material is 1% by mass or more and less than 100% by mass. Is preferred.

  Then, the surface layer (9) containing transparent resin (B) is laminated | stacked on the single side | surface or both surfaces of the base layer (8) which consists of said resin for base layers, and a 2nd laminated board is obtained (S4).

  Next, at least a part of the peripheral edge of the obtained second laminated plate is cut to obtain a product (second laminated resin plate) (3) having a predetermined size, and the cut portion is set to the second end. Sort as material (S5). These S3, S4, and S5 are a 2nd edge material acquisition process.

  The second laminated resin plate (3) thus obtained has a surface layer (B) containing the transparent resin (B) on both sides of the base layer (8) containing the transparent resin (A) and the transparent resin (B). 9) Although (9) is laminated, since the relational expression Δδ × Δn ≦ 0.42 is established between the transparent resin (A) and the transparent resin (B), the first end Although the material is reused as a part of the constituent material of the base layer (8), the second laminated resin plate (3) in which coloring such as yellow is sufficiently suppressed can be manufactured. Moreover, even if the ratio of reusing the first mill ends as a part of the constituent material of the base layer (8) is increased (that is, the ratio of recycled contents of the mill ends is increased), coloring such as yellow is sufficiently suppressed. it can.

  Thus, although the said 2nd laminated resin board (3) obtained through S3 and S4 was manufactured by using a scrap for one time reuse (refer FIG. 2), the manufacturing method of this invention Then, the following steps may be further performed to manufacture a laminated resin plate.

  That is, the base layer resin is prepared by mixing the second end material produced in the cutting step of S5 with the transparent resin (A) (S6). At this time, in the same manner as described above, the composition of the base layer resin is mixed so that the content of the second end material relative to the total amount of the transparent resin (A) and the second end material is 1% by mass or more and less than 100% by mass. Is preferably prepared.

  Then, the surface layer (9) containing transparent resin (B) is laminated | stacked on the single side | surface or both surfaces of the base layer (8) which consists of said resin for base layers, and a 3rd laminated board is obtained (S7).

  Next, at least a part of the peripheral portion of the obtained third laminated board is cut to obtain a product (third laminated resin board) (3) having a predetermined size, and the cut part is taken to the third end. Sort as material (S8). These S6, S7, and S8 are a 3rd end material acquisition process.

  The 3rd laminated resin board (3) obtained in this way contains transparent resin (B) on both surfaces of the base layer (8) containing transparent resin (A) and transparent resin (B) similarly to the above. The surface layers (9) and (9) are stacked. Here, the second end material reused in S6 is originally formed by mixing the first end material reused in the previous S3 into the base layer, so to speak, it is used for the second reuse. Therefore, the content of the transparent resin (B) in the base layer resin composition obtained in S6 is the same as the transparent resin (B) in the base layer resin composition obtained in the previous S3. However, since the relational expression of Δδ × Δn ≦ 0.42 is established between the transparent resin (A) and the transparent resin (B), coloring is still sufficient. It is possible to obtain a laminated resin plate that is suppressed by the above.

  Next, a base layer resin is prepared by mixing the third end material with the transparent resin (A) (S9). In the same manner as described above, the composition of the base layer resin is prepared by mixing so that the content of the third end material relative to the total amount of the transparent resin (A) and the third end material is 1% by mass or more and less than 100% by mass. Is preferred.

  Hereinafter, by repeating the steps S7 to S9 in the same manner, the laminated resin plates (the fourth laminated resin plate and the fifth laminated resin plate) in which coloring such as yellow is sufficiently suppressed while reusing the scraps produced in the manufacturing process. The sixth laminated resin plate (...) (3) can be manufactured. That is, when the milled material is reused twice, three times, or four times or more, the recycled content ratio of the milled material in the resulting laminated resin plate (3) gradually increases. As described above, since a configuration in which the relational expression Δδ × Δn ≦ 0.42 is established between the transparent resin (A) and the transparent resin (B), the end material is reused a plurality of times. Also, it is possible to obtain a laminated resin plate (3) in which coloring such as yellow is sufficiently suppressed. As described above, in this manufacturing method, since the milling material can be reused once, it is possible to suppress coloring such as yellow even when the milling material is reused multiple times. Suitable for industrial production.

  The method for laminating the base layer (8) and the surface layer (9) is not particularly limited, but for example, a coextrusion molding method, a bonding method, a thermal bonding method, a solvent bonding method, a polymerization bonding method. Examples thereof include a method such as a method, a cast polymerization method, and a surface coating method. Among them, a coextrusion method that is easy to work and has high production efficiency and does not require the use of other materials such as an adhesive is preferable.

  In addition, when mixing the end material with the transparent resin (A), a defective product that cannot be provided as a product due to scratches, dirt, cracks, etc. (laminated resin plate with poor quality) is transparent together with the end material. You may mix with resin (A).

  In the above embodiment, the base layer resin is prepared by mixing the transparent resin (A) and the mill ends in the base layer resin preparation step (S3, S6, S9). However, the present invention is particularly limited to this. Instead of the above, the end material may be used as the base layer resin (the transparent resin (A) cannot be mixed).

  In this invention, as the transparent resin (A) and the transparent resin (B), the absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the transparent resin As long as the absolute value of the difference between the refractive index of (A) and the refractive index of the transparent resin (B) is “Δn”, the transparent resins satisfying the relational expression of Δδ × Δn ≦ 0.42 are established. Anything can be used. Table 1 below lists the numerical values of “Δδ × Δn” in a combination of two resins. For example, in such a combination, a resin having a combination in which Δδ × Δn is 0.42 or less. One can be used as the transparent resin (A) and the other as the transparent resin (B). In Table 1, since Δδ × Δn exceeds 0.42 in the combinations marked with “*”, it cannot be adopted as the combination of the transparent resin (A) and the transparent resin (B) in the present invention (the present invention). Cannot achieve the effect).

  Table 2 shows the value of “Δδ” that is the basis for the calculation of “Δδ × Δn” in Table 1. Table 3 shows the value of “Δn” that is the basis for the calculation of “Δδ × Δn” in Table 1. Show. Table 4 shows the SP value of each resin that is the basis for calculating “Δδ” and the value of the refractive index n of each resin that is the basis for calculating “Δn”.

  Here, the refractive index is a value measured according to JIS K7142-1996 using a refractometer “Multiwave Abbe Refractometer DR-M4” manufactured by Atago Co., Ltd. (definition).

However, for the calculation of Δn in Table 3 and the refractive index n of each resin in Table 4, for convenience, the refractive index of the resin described in Document 1 below is used, and for the resin not described in Document 1, the following document is used. 2 was used. In addition, when there is no description of the refractive index of a copolymer in these literatures 1 and 2, it calculated by the molar ratio of the refractive index of a known resin and the component of each unit monomer, ie, the refractive index of a copolymer. Was calculated by adding the product of the refractive index of each unit monomer and the molar ratio of each component. These points are the same in the embodiments described later.
Reference 1: “POLYMER HANDBOOK (THIRD EDITION)”, author: BRANDRUP and E. H. IMMERGUT, Publisher: A WILEY-INTERSCIENCE PUBLICATION, 1989, p. VI / 453-VI / 461
Reference 2: “Transparent resin in the light age”, supervisor: Fumio Ide, publisher: CMC Publishing, published June 30, 2004, 1st edition, Chapter 10, p. 128-137.

The SP value is a Hansen solubility parameter (solubility parameter calculated by the Hansen method). According to Hansen, the solubility parameter δ is defined by three-dimensional parameters (δd, δp, δh), that is, defined by the following equation (2). This concept (theory) proposed by Hansen is described in “PROPERITES OF POLYMERS” (author: DW VAN KREVEREN, publisher: ELSEVIER SCIENTIFIC PUBLISHING COMPANY, 1989, 5th edition).
δ ² = (δd) ² + (δp) ² + (δh) ² (2)
δd: London dispersion force term δp: molecular polarization term (dipole force term)
δh: hydrogen bond term Therefore, in the present invention, “Δδ” is defined by the following equation (3).
(Δδ) ² = (δd ₁ -δd ₂ ) ² + (δp ₁ -δp ₂ ) ² + (δh ₁ -δh ₂ ) ² (3)
δd ₁ : London dispersion force term of transparent resin (A) δd ₂ : London dispersion force term of transparent resin (B) δp ₁ : Molecular polarization term of transparent resin (A) δp ₂ : Molecular polarization term of transparent resin (B) δh ₁ : Hydrogen bond term of transparent resin (A) δh ₂ : Hydrogen bond term of transparent resin (B)

  In the present invention, the Hansen solubility parameter (SP value) is specifically determined as follows.

  1) The group molar pulling constants (Fdi, Fpi, Ehi) and molar volume (Vi) of each functional group were determined according to “PROPERITES OF POLYMERS” (author: DW VAN KREVELEN, publisher: ELSEVIER SCIENTIFIC PUBLISHING COMPANY, 1989). It is calculated according to the description items and technique of “CHAPTER7 COHESIVE PROPERITES AND SOLUBILITY” (pages 129 to 158) of the fifth edition).

2) The unit group molar pulling constant of the polymer (resin) is determined from the group molar pulling constant (Fdi, Fpi, Ehi) and the molar volume (Vi) of each functional group determined in 1) above.
δd = ΣFdi / ΣVi (4)
δp = (Σ (Fpi) ² ) ^1/2 / ΣVi (5)
δh = (ΣEhi / ΣVi) ^1/2 (6)
It calculates by said Formula (4), Formula (5), and Formula (6), respectively.

  3) For a polymer (copolymer) containing a plurality of monomer units, it is calculated by multiplying the molar ratio of each unit monomer.

  As the transparent resin (A) and the transparent resin (B), it is preferable to use transparent resins satisfying the relational expression of Δδ × Δn ≦ 0.30, particularly preferably Δδ × Δn ≦ 0. The transparent resins satisfy 20 relational expressions. In this way, when the value of “Δδ × Δn” is smaller, a laminated resin plate (light) in which coloring such as yellow is sufficiently suppressed even when the end material is used more as a part of the constituent material of the base layer. Diffusion plate etc.) can be manufactured.

  The absolute value of the difference between the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B), that is, Δn is preferably 0.03 or more and 0.15 or less, and more preferably 0.032 or more and 0. .13 or less is more preferable.

  Further, the absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B), that is, Δδ is preferably 0.0 or more and 12.0 or less. Even if the ratio of reusing as a part of the constituent material of the base layer is further increased, coloring such as yellow can be sufficiently suppressed. Among them, Δδ is more preferably 0.0 or more and 10.0 or less.

  The combinations of the transparent resin (A) and the transparent resin (B) shown in Table 1 are merely examples, and are not particularly limited to these examples. That is, as the transparent resin (A) and the transparent resin (B), as long as the relational expression Δδ × Δn ≦ 0.42 is established, for example, a combination of the following transparent resins can be used. it can. For example, methacrylic resin, MS resin (styrene-methyl methacrylate copolymer), ABS resin (acrylonitrile-butadiene-styrene copolymer), polystyrene, AS resin (acrylonitrile-styrene copolymer), polyethylene, polypropylene, cyclic olefin Examples thereof include resins.

  Among these, it is preferable to use a styrene resin as the transparent resin (A) and a styrene resin or an acrylic resin as the transparent resin (B). Of course, also in this case, the styrene resin as the transparent resin (A) and the styrene resin or acrylic resin as the transparent resin (B) satisfy the relational expression Δδ × Δn ≦ 0.42. Must be a thing.

  The styrene resin is a resin having a styrene monomer unit content of 50 to 100% by mass. As the styrene monomer, for example, substituted styrenes can be used in addition to styrene. Examples of the substituted styrenes include, but are not limited to, halogenated styrenes such as chlorostyrene and bromostyrene, and alkylstyrenes such as vinyltoluene and α-methylstyrene. The styrenic monomer may be used alone or in combination of two or more.

  The monomer other than the styrene monomer that can be included as a monomer unit in the styrenic resin is not particularly limited. For example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, Cyclohexyl methacrylate, octadecyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, adamantyl methacrylate, tricyclodecyl methacrylate, fentil methacrylate, norbornyl methacrylate, nor methacrylate Methacrylic acid esters such as bornylmethyl, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, acrylic Acrylic acid esters such as 2-hydroxyethyl acrylate and tricyclodecyl acrylate, unsaturated acids such as methacrylic acid and acrylic acid, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, glutaric anhydride, A glutarimide etc. are mentioned, These 2 or more types may be included.

  The acrylic resin is a resin containing 50% by mass or more of methyl methacrylate as a monomer unit, and may be substantially a homopolymer of methyl methacrylate, or 50% by mass of methyl methacrylate. It may be a copolymer obtained by copolymerizing the above and 50% by mass or less of other monomers copolymerizable therewith.

  Other monomers other than methyl methacrylate (other monomers copolymerizable with methyl methacrylate) that can be included as a monomer unit in the acrylic resin are not particularly limited. For example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, octadecyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, adamantyl methacrylate, tricyclodecyl methacrylate, Methacrylic acid esters such as fenthyl methacrylate, norbornyl methacrylate, norbornyl methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, Acrylic acid esters such as 2-ethylhexyl silylate, 2-hydroxyethyl acrylate and tricyclodecyl acrylate, unsaturated acids such as methacrylic acid and acrylic acid, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexyl Maleimide, glutaric anhydride, glutarimide, styrenic monomer and the like may be mentioned, and two or more of these may be included. As said styrene-type monomer, you may use said substituted styrene other than styrene. The acrylic resin may contain a glutaric anhydride unit or a glutarimide unit.

  The base layer (8) may contain light diffusing particles. In this case, the light diffusing plate is suitable. The light diffusing particles are particles having a refractive index different from that of the resin or mixed resin constituting the base layer (8), and the particles are dispersed and contained to transmit the laminated resin plate (light diffusing plate). There is no particular limitation as long as it can diffuse light. For example, the particles may be inorganic particles such as glass particles, glass fibers, silica particles, aluminum hydroxide particles, calcium carbonate particles, barium sulfate particles, titanium oxide particles, talc, styrene polymer particles, acrylic polymers. Organic particles such as particles and siloxane polymer particles may be used.

  Further, in the base layer (8), an ultraviolet absorber, a heat stabilizer, an antioxidant, a weathering agent, a light stabilizer, a fluorescent whitening agent, a processing stabilizer, and a nucleating agent as long as the effects of the present invention are not impaired. Such additives may be included.

  Similarly, to the extent that the effects of the present invention are not impaired, the surface layer (9) is provided with an ultraviolet absorber, a heat stabilizer, an antioxidant, a weathering agent, a light stabilizer, a fluorescent brightening agent, a processing stabilizer, An additive such as a nucleating agent may be included.

  The thickness (R) of the base layer (8) is usually 50 to 2990 μm. When it is 50 μm or more, sufficient strength can be secured, and when it is 2990 μm or less, an increase in cost can be suppressed. Among them, the thickness (R) of the base layer (8) is preferably 100 μm or more and 2980 μm or less, and more preferably 2500 μm or less.

  The thickness (T) of the surface layer (9) is usually 10 to 300 μm. A surface layer having a stable thickness can be obtained when the thickness is 10 μm or more, and an increase in cost can be suppressed when the thickness is 300 μm or less. Among them, the thickness (T) of the surface layer (9) is preferably 20 μm or more and 200 μm or less.

  The thickness of the base layer is preferably set in the range of 9 to 100 times the thickness (one side) of the surface layer. When it is 9 or more, an increase in cost can be suppressed, and when it is 100 or less, a surface layer having a stable thickness can be obtained. Especially, it is more preferable that the thickness of the base layer is set in a range of 10 to 80 times the thickness of the surface layer. In addition, the thickness of the said laminated resin board is 0.05 mm-5 mm normally, Preferably it is the range of 0.1-4 mm, More preferably, it is set to the range of 0.2-3 mm.

  In the above embodiment, the structure in which the surface layers (9) and (9) are laminated and integrated on both surfaces of the base layer (8) is employed (see FIG. 1), but the structure is particularly limited to such a structure. Instead, a configuration in which the surface layer (9) is laminated and integrated on one surface of the base layer (8) may be employed. However, it is preferable to adopt a configuration in which the surface layers (9) and (9) are laminated and integrated on both surfaces of the base layer (8) as in the above-described embodiment in that the warpage can be more sufficiently prevented.

  Further, the surface of the laminated resin plate (3) may be formed as a smooth surface, or may be formed into a mat shape, a lens shape or the like, and is not particularly limited.

  A preferred structure for the laminated resin plate (3) obtained by the production method of the present invention is a base layer (8) containing 100 parts by mass of the transparent resin (A) and 0.01 to 20 parts by mass of the transparent resin (B). And a surface layer (9) which is laminated and integrated on one side or both sides of the base layer and contains a transparent resin (B), wherein the thickness of the base layer is the thickness of the surface layer ( It is a configuration set in a range of 9 to 100 times that of one side. The laminated resin plate having such a configuration is sufficiently suppressed in coloring.

  Note that the method for producing a laminated resin plate according to the present invention is not particularly limited to that of the above-described exemplary embodiment, and any design change is within the scope of the claims, as long as it does not depart from the spirit. Is also allowed.

  Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
90.90 parts by mass of styrene-methyl methacrylate copolymer (styrene unit content: about 80% by mass, methyl methacrylate unit content: about 20% by mass, “MS200” manufactured by Nippon Steel Chemical Co., Ltd.) Acrylic polymer particles (crosslinked polymer particles) (“SUMIPEX XC1A” manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter of about 25 μm) 8.00 parts by mass, ADK STAB LA31 (benzotriazole ultraviolet absorber, manufactured by ADEKA) 00 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, and after dry blending, the mixture is supplied to an extruder with a screw diameter of 40 mm and melt-kneaded to form a resin composition for surface layer formation Product B1 was obtained.

  The surface layer forming resin composition B1 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  On the other hand, 84.45 parts by mass of polystyrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd.), acrylic polymer particles (crosslinked polymer particles) (“Paralloid EXL5766” manufactured by Rohm & Haas Co., volume average particle diameter of about 0.8 μm) 14.00 parts by mass, Sumsorb 200 (benzotriazole ultraviolet absorber, manufactured by Sumitomo Chemical Co.) 1.00 parts by mass, Sumizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co.) 0.50 parts by mass, White Flow PSN (Fluorescent) A masterbatch resin composition A1 was obtained by dry blending 0.05 part by weight of a whitening agent (manufactured by Sumika Color Co., Ltd.).

  After dry blending 100 parts by weight of polystyrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd.), 4.63 parts by weight of the resin composition B1 for forming the surface layer, and 11.00 parts by weight of the masterbatch resin composition A1, It supplied to the 1st extruder with a screw diameter of 40 mm, melt-kneaded at 250 degreeC, and supplied to the multi manifold die.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  The polystyrene resin (transparent resin (A)) and the styrene-methyl methacrylate copolymer (styrene unit content: about 80% by mass, methyl methacrylate unit content: about 20% by mass) (transparent Since Δδ × Δn with respect to resin (B)) is 0.093 (see Table 1), a relational expression of Δδ × Δn ≦ 0.42 is established between these two resins.

  The laminated resin plate (3) obtained in Example 1 has a transparent resin (A) base layer thickness of 1.9 mm and a transparent resin (B) surface layer thickness of 0.05 mm (both sides). From the resin composition obtained by cutting the peripheral edge of the laminated board having a total of 0.10 mm) and separating it as an end material, and mixing 92 parts by mass of the end material and 8 parts by mass of the transparent resin (A) This corresponds to a laminated resin plate produced by laminating a surface layer made of a transparent resin (B) and having a thickness of 0.05 mm on both sides of a 1.9 mm thick base layer.

<Example 2>
Three-layer laminated resin in the same manner as in Example 1 except that the content ratio of each component and the thickness of each layer in the resin composition (for the base layer) supplied to the first extruder were set to the conditions shown in Table 1, respectively. A light diffusing plate made of the plate (3) was produced.

  The laminated resin plate (3) obtained in Example 2 has a transparent resin (A) base layer thickness of 1.6 mm and a transparent resin (B) surface layer thickness of 0.2 mm (both sides). From the resin composition obtained by cutting the peripheral portion of the laminate having a total of 0.4 mm) and separating it as an end material, and mixing 49 parts by mass of the end material and 51 parts by mass of the transparent resin (A) This corresponds to a laminated resin plate produced by laminating a surface layer made of transparent resin (B) and having a thickness of 0.05 mm on both surfaces of a 1.9 mm thick base layer.

<Reference Example 1>
The surface layer forming resin composition B1 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  After dry blending 100.00 parts by mass of polystyrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd.) and 11.00 parts by mass of the masterbatch resin composition A1, the mixture is supplied to a first extruder having a screw diameter of 40 mm and 250 ° C. And kneaded and fed to a multi-manifold die.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  This reference example 1 corresponds to the case where the end material of the laminated plate is not used at all as the constituent material of the base layer.

<Example 3>
Styrene-methyl methacrylate copolymer (styrene unit content: about 80% by mass, methyl methacrylate unit content: about 20% by mass) (“MS200” manufactured by Nippon Steel Chemical Co., Ltd.) 78.55 parts by mass, 1. Acrylic polymer particles (crosslinked polymer particles) (Sumitomo Chemical “Sumipex XC1A”, volume average particle diameter of about 25 μm) 20.00 parts by mass, ADK STAB LA31 (benzotriazole UV absorber, manufactured by ADEKA) After dry blending 00 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.20 parts by mass, Balu HSP311 (release agent, manufactured by Maruhishi Oil Chemical Co., Ltd.), the screw diameter By supplying it to a 40 mm extruder and melt-kneading, a surface layer forming resin composition B2 was obtained.

  The surface layer forming resin composition B2 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  On the other hand, styrene-methacrylic acid copolymer (styrene unit content: about 90.5 mass%, methacrylic acid unit content: about 9.5 mass%) ("T080" manufactured by Toyo Styrene Co., Ltd.) 96.70 mass Parts, silicone rubber particles ("Toy Dow Corning" DY33-719 ") 0.10 parts by mass, acrylic polymer particles (cross-linked polymer particles) (Sekisui Plastics" MBX2H ", volume average particle diameter About 3 μm) 0.50 parts by mass, Sumisorb 200 (benzotriazole ultraviolet absorber, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, the above surface After 2.50 parts by mass of the layer forming resin composition B2 is dry blended, it is supplied to a first extruder having a screw diameter of 40 mm and melt-kneaded at 250 ° C. to form a multi-manifold die. The paper was.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  The styrene-methacrylic acid copolymer (styrene unit content: about 90.5% by mass, methacrylic acid unit content: about 9.5% by mass) (transparent resin (A)) and the styrene- Δδ × Δn between the methyl methacrylate copolymer (content of styrene units: about 80% by mass, content of methyl methacrylate units: about 20% by mass) (transparent resin (B)) is 0.088 Therefore (see Table 1), a relational expression of Δδ × Δn ≦ 0.42 is established between these two resins.

  The laminated resin plate (3) obtained in Example 3 has a transparent resin (A) base layer thickness of 1.9 mm and a transparent resin (B) surface layer thickness of 0.05 mm (both sides). From the resin composition obtained by cutting the peripheral portion of the laminate having a total of 0.10 mm) and separating it as an end material, and mixing the end material 50 parts by mass with the transparent resin (A) 50 parts by mass This corresponds to a laminated resin plate produced by laminating a surface layer made of a transparent resin (B) and having a thickness of 0.05 mm on both sides of a 1.9 mm thick base layer.

<Reference Example 2>
The surface layer forming resin composition B1 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  Styrene-methacrylic acid copolymer (styrene unit content: about 90.5% by mass, methacrylic acid unit content: about 9.5% by mass) (“T080” manufactured by Toyo Styrene Co., Ltd.) 99.20 parts by mass, 0.10 parts by mass of silicone rubber particles ("DY33-719" manufactured by Toray Dow Corning), acrylic polymer particles (crosslinked polymer particles) ("MBX2H" manufactured by Sekisui Plastics Co., Ltd.), volume average particle diameter of about 3 μm ) After dry blending 0.50 parts by mass, SUMISOB 200 (benzotriazole-based UV absorber, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, and Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass The mixture was supplied to a first extruder having a screw diameter of 40 mm, melted and kneaded at 250 ° C., and supplied to a multi-manifold die.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  This Reference Example 2 corresponds to the case where the end material of the laminated plate is not used at all as the constituent material of the base layer.

<Example 4>
Styrene-methyl methacrylate copolymer (content of styrene units: about 40% by mass, content of methyl methacrylate units: about 60% by mass) (“MS600” manufactured by Nippon Steel Chemical Co., Ltd.) 78.55 parts by mass, 1. Acrylic polymer particles (crosslinked polymer particles) (Sumitomo Chemical “Sumipex XC1A”, volume average particle diameter of about 25 μm) 20.00 parts by mass, ADK STAB LA31 (benzotriazole UV absorber, manufactured by ADEKA) After dry blending 00 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.20 parts by mass, Balu HSP311 (release agent, manufactured by Maruhishi Oil Chemical Co., Ltd.), screw diameter By supplying it to a 40 mm extruder and melt-kneading, a surface layer forming resin composition B3 was obtained.

  The surface layer forming resin composition B3 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  On the other hand, styrene-methacrylic acid copolymer (styrene unit content: about 90.5 mass%, methacrylic acid unit content: about 9.5 mass%) ("T080" manufactured by Toyo Styrene Co., Ltd.) 96.70 mass Parts, silicone rubber particles ("Toy Dow Corning" DY33-719 ") 0.10 parts by mass, acrylic polymer particles (crosslinked polymer particles) (Sekisui Plastics" MBX2H ", volume average particle diameter About 3 μm) 0.50 parts by mass, Sumisorb 200 (benzotriazole ultraviolet absorber, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, the above surface After 2.50 parts by mass of the layer forming resin composition B3 is dry blended, it is supplied to a first extruder having a screw diameter of 40 mm and melt-kneaded at 250 ° C. to form a multi-manifold die. The paper was.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  The styrene-methacrylic acid copolymer (styrene unit content: about 90.5% by mass, methacrylic acid unit content: about 9.5% by mass) (transparent resin (A)) and the styrene- Δδ × Δn with respect to the methyl methacrylate copolymer (styrene unit content: about 80% by mass, methyl methacrylate unit content: about 20% by mass) (transparent resin (B)) is 0.271. Therefore (see Table 1), a relational expression of Δδ × Δn ≦ 0.42 is established between these two resins.

  In the laminated resin plate (3) obtained in Example 4, the thickness of the transparent resin (A) base layer was 1.9 mm, and the thickness of the transparent resin (B) surface layer was 0.05 mm (both sides). From the resin composition obtained by cutting the peripheral portion of the laminate having a total of 0.10 mm) and separating it as an end material, and mixing the end material 50 parts by mass with the transparent resin (A) 50 parts by mass This corresponds to a laminated resin plate produced by laminating a surface layer made of a transparent resin (B) and having a thickness of 0.05 mm on both sides of a 1.9 mm thick base layer.

<Reference Example 3>
The surface layer forming resin composition B3 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  On the other hand, styrene-methacrylic acid copolymer (styrene unit content: about 90.5 mass%, methacrylic acid unit content: about 9.5 mass%) ("T080" manufactured by Toyo Styrene Co., Ltd.) 99.20 mass Parts, silicone rubber particles ("Toy Dow Corning" DY33-719 ") 0.10 parts by mass, acrylic polymer particles (cross-linked polymer particles) (Sekisui Plastics" MBX2H ", volume average particle diameter About 3 μm) 0.50 parts by mass, Sumisorb 200 (benzotriazole UV absorber, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, dry blended Then, it was supplied to a first extruder having a screw diameter of 40 mm, melted and kneaded at 250 ° C., and supplied to a multi-manifold die.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  This Reference Example 3 corresponds to the case where the end material of the laminated plate is not used at all as the constituent material of the base layer.

<Comparative Example 1>
90.90 parts by mass of a styrene-methyl methacrylate copolymer (content of styrene units: about 40% by mass, content of methyl methacrylate units: about 60% by mass) (“MS600” manufactured by Nippon Steel Chemical Co., Ltd.) Acrylic polymer particles (crosslinked polymer particles) (“SUMIPEX XC1A” manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter of about 25 μm) 8.00 parts by mass, ADK STAB LA31 (benzotriazole ultraviolet absorber, manufactured by ADEKA) 00 parts by mass, Sumilizer GP (processing stabilizer, manufactured by Sumitomo Chemical Co., Ltd.) 0.10 parts by mass, and after dry blending, the mixture is supplied to an extruder with a screw diameter of 40 mm and melt-kneaded to form a resin composition for surface layer formation Product B4 was obtained.

  The surface layer forming resin composition B4 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  On the other hand, 100 parts by mass of polystyrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd.), 2.20 parts by mass of the resin composition B4 for forming the surface layer, and 11.00 parts by mass of the masterbatch resin composition A1 were dry blended. Then, it supplied to the 1st extruder with a screw diameter of 40 mm, melt-kneaded at 250 degreeC, and supplied to the multi manifold die.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  The polystyrene resin (transparent resin (A)) and the styrene-methyl methacrylate copolymer (styrene unit content: about 40% by mass, methyl methacrylate unit content: about 60% by mass) (transparent Since Δδ × Δn with respect to the resin (B) is 0.495 (see Table 1), the relational expression Δδ × Δn ≦ 0.42 does not hold between these two resins.

  The laminated resin plate obtained in Comparative Example 1 has a transparent resin (A) base layer thickness of 1.9 mm and a transparent resin (B) surface layer thickness of 0.05 mm (total of both sides is 0). .10 mm), the peripheral portion of the laminated plate is cut and separated as end material, and the thickness is made of a resin composition obtained by mixing 44 parts by mass of the end material and 56 parts by mass of the transparent resin (A). This corresponds to a laminated resin plate produced by laminating a surface layer made of transparent resin (B) and having a thickness of 0.05 mm on both sides of a 1.9 mm base layer.

<Reference Example 4>
The surface layer forming resin composition B4 was supplied to a second extruder having a screw diameter of 20 mm, melt-kneaded at 250 ° C., and supplied to a multi-manifold die.

  On the other hand, 100 parts by mass of polystyrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd.) and 11.00 parts by mass of the masterbatch resin composition A1 were dry-blended, and then supplied to a first extruder having a screw diameter of 40 mm at 250 ° C. And kneaded and fed to a multi-manifold die.

  The resin composition supplied from the first extruder to the multi-manifold die becomes the base layer (8), and the resin composition supplied from the second extruder to the multi-manifold die becomes the surface layer (9) (9). Thus, co-extrusion is performed at a temperature of 245 to 250 ° C., and from a three-layer laminated resin plate (3) having a thickness of 2.0 mm (base layer 1.9 mm, surface layer 0.05 mm × 2) as shown in FIG. A light diffusion plate was produced.

  This reference example 4 corresponds to the case where the end material of the laminated plate is not used at all as the constituent material of the base layer.

  Each light diffusion plate obtained as described above was evaluated according to the following evaluation method. The evaluation results are shown in Tables 5 and 6.

<Total light transmittance measurement method>
Based on JIS K7361-1997, the total light transmittance (%) of the light diffusing plate was measured.

<Diffusion light transmittance measurement method>
Based on JIS K7136-2000, the diffused light transmittance (%) of the light diffusing plate was measured.

<Haze value measuring method>
The haze (%) of the light diffusion plate was measured according to JIS K7136-2000.

<Measurement method of yellowness YI by spectral transmittance measurement>
The spectral transmittance in the wavelength range of 380 to 780 nm of the light diffusing plate was measured using a self-recording spectrophotometer equipped with an integrating sphere (“UV-4000” manufactured by Hitachi, Ltd.), and the yellowness YI was calculated based on this. .

<Diffusion rate measurement method>
Using an automatic goniophotometer ("GP-1R" manufactured by Murakami Color Research Laboratory Co., Ltd.), in the normal direction of the transmitted light when light is incident on the light diffusing plate from the normal direction intensity of transmitted light to the 5 ° of the intensity I ₅ of the transmitted light to the angle, the transmitted light intensity I ₂₀ to an angle of 20 ° to the normal direction, an angle of 70 ° to the normal direction for Measure I ₇₀ respectively
D = 100 × (I ₂₀ + I ₇₀ ) / (2 × I ₅ )
The diffusivity D (%) was determined by the above formula.

  As is clear from Tables 5 and 6, the light diffusion plates of Examples 1 to 4 manufactured by the manufacturing method of the present invention have a small yellowness YI and are sufficiently suppressed in coloring. That is, for example, as is clear from the comparison of the YI values of Reference Example 1 and Examples 1 and 2, the comparison of the YI values of Reference Example 2 and Example 3, and the comparison of the YI values of Reference Example 3 and Example 4, the base layer Even when the mixing ratio of the resin composition for forming the surface layer in (i.e., the recycled content ratio of the mill ends was large), the yellowness YI was suppressed to be small. That is, the YI values of Examples 1 and 2 in which the end material was reused are equivalent to the YI values in Reference Example 1 in which the end material was not reused, and the end material was reused. The YI value of 3 is equivalent to the YI value of Reference Example 2 in which the end material was not reused, and the YI value of Example 4 in which the end material was reused did not reuse the end material. It was equivalent to the YI value of Reference Example 3.

  In the light diffusion plates of Examples 1 to 4, even when the mixing ratio of the resin composition for forming the surface layer in the base layer is large (that is, the recycled content ratio of the mill ends is large), the total light transmittance and diffusion The light transmittance was almost constant with almost no change.

  In the manufacturing method of the present invention, when the milling material is reused a plurality of times, the recycling content ratio of milling material in the laminated resin plate gradually increases every time the milling material is reused. However, even in such a case, the yellowness YI is suppressed to be small, and the total light transmittance and the diffused light transmittance are hardly changed. Therefore, if the manufacturing method of the present invention is adopted, the end material is reduced. While being reused, a laminated resin plate having stable quality can be produced.

  On the other hand, in the light diffusing plate of Comparative Example 1 in which the relational expression of Δδ × Δn ≦ 0.42 is not established, the yellowness YI is relatively large and slightly yellowish due to the reuse of the end material. was there. That is, as is clear from the comparison of the YI values of Reference Example 4 and Comparative Example 1, when the mixing ratio of the surface layer forming resin composition in the base layer is large (that is, the recycle content ratio of the mill ends is large), the yellowness YI increased relatively greatly, and yellow coloring became conspicuous. Further, as apparent from the comparison of the YI values of Reference Example 4 and Comparative Example 1, when the mixing ratio of the surface layer forming resin composition in the base layer is large (that is, when the recycled content ratio of the mill ends is large), the diffusivity Fell.

  The laminated resin plate produced by the production method of the present invention is suitable, for example, as a light diffusing plate, and particularly suitably as a light diffusing plate for a surface light source device used as a backlight for a liquid crystal display device. However, it is not limited to such an application.

3 ... Laminated resin plate (light diffusion plate)
8 ... Base layer 9 ... Surface layer R ... Base layer thickness T ... Surface layer thickness

Claims (10)

After laminating a surface layer containing the transparent resin (B) on at least one surface of the base layer containing the transparent resin (A) to obtain a laminate, at least a part of the peripheral edge of the laminate is obtained. Cutting material acquisition process of cutting and separating as cutting material,
A surface layer containing a transparent resin (B) is laminated on at least one side of a base layer made of a resin composition obtained by mixing the transparent resin (A) and the end material or made of the end material. A step of manufacturing a resin plate,
The absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) A manufacturing method of a laminated resin plate, wherein a relational expression of Δδ × Δn ≦ 0.42 is satisfied when an absolute value of the difference is “Δn”. After laminating a surface layer containing the transparent resin (B) on at least one side of the base layer containing the transparent resin (A) to obtain the first laminated plate, the peripheral portion of the first laminated plate A first end material acquisition step of cutting at least a part and separating the first end material;
A surface layer comprising a transparent resin (B) on at least one side of a base layer comprising a resin composition obtained by mixing a transparent resin (A) and the first end material or comprising the first end material. After obtaining the second laminate by laminating, a second end material acquisition step of cutting at least a part of the peripheral edge of the second laminate and separating it as a second end material;
A surface layer comprising a transparent resin (B) on at least one surface of a base layer comprising a resin composition obtained by mixing the transparent resin (A) and the second end material or comprising the second end material. And laminating to produce a laminated resin plate,
The absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) A manufacturing method of a laminated resin plate, wherein a relational expression of Δδ × Δn ≦ 0.42 is satisfied when an absolute value of the difference is “Δn”.   While setting the thickness of the base layer in the said laminated board to the range of 9-100 times the thickness of a surface layer, when mixing the said transparent resin (A) and the said end material, the said transparent resin (A) and the said edge The manufacturing method of the laminated resin board of Claim 1 or 2 mixed so that the content rate of the said end material with respect to the total amount of material may be 1 mass% or more and less than 100 mass%.   The manufacturing method of the laminated resin board of any one of Claims 1-3 with which the relational expression of 0.03 <= (DELTA) n <= 0.15 is materialized.   The method for producing a laminated resin plate according to claim 1, wherein the transparent resin (A) is a styrene resin, and the transparent resin (B) is a styrene resin or an acrylic resin. A base layer containing 0.01 to 20 parts by mass of the transparent resin (B) with respect to 100 parts by mass of the transparent resin (A);
A surface layer containing a transparent resin (B) that is laminated and integrated on one or both sides of the base layer, and
The thickness of the base layer is in the range of 9 to 100 times the thickness of the surface layer;
The absolute value of the difference between the SP value of the transparent resin (A) and the SP value of the transparent resin (B) is “Δδ”, and the refractive index of the transparent resin (A) and the refractive index of the transparent resin (B) A laminated resin plate characterized in that a relational expression of Δδ × Δn ≦ 0.42 holds when an absolute value of the difference is “Δn”.   The said base layer contains 0.01-20 mass parts of said transparent resin (B), and 0.01-10 mass parts of light-diffusion particle | grains with respect to 100 mass parts of said transparent resin (A). The laminated resin plate described.   The laminated resin plate according to claim 6 or 7, wherein the transparent resin (A) is a styrene resin, and the transparent resin (B) is a styrene resin or an acrylic resin.   A surface light source device comprising: a light diffusing plate comprising the laminated resin plate according to any one of claims 6 to 8; and a plurality of light sources disposed on a back side of the light diffusing plate.   A light diffusing plate comprising the laminated resin plate according to any one of claims 6 to 8, a plurality of light sources arranged on a back side of the light diffusing plate, and a front side of the light diffusing plate. A liquid crystal display device comprising a liquid crystal panel.

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