WO2007094209A1

WO2007094209A1 - Method for manufacturing molded flat plate, and molded flat plate

Info

Publication number: WO2007094209A1
Application number: PCT/JP2007/052089
Authority: WO
Inventors: Masahiko Hayashi; Noboru Muraoka; Kazunori Ueki
Original assignee: Zeon Corporation
Priority date: 2006-02-13
Filing date: 2007-02-07
Publication date: 2007-08-23
Also published as: JPWO2007094209A1; KR20080101904A; TW200740596A

Abstract

A plurality of gates (20) are arranged on a substantially rectangular cavity surface (10). The gates (20) are arranged along the longitudinal direction or the lateral direction at substantially equal intervals. A plurality of gates are arranged by three lateral gate rows (22) and four longitudinal gate rows. A lateral gate row (22B) at the middle of the three lateral gate rows is permitted to be a first lateral gate row (X), and lateral gate rows (20A, 20C) outside the middle lateral gate row are permitted to be second lateral gate rows (Y). A resin is projected from the first lateral gate row (X), and when the projecting quantity of the resin becomes a prescribed quantity, the resin is projected from the second lateral gate rows (Y) and a molded flat plate is manufactured.

Description

Specification

Method for producing flat plate molded product and flat plate molded product

Technical field

The present invention relates to a method for producing a flat plate molded product and a flat plate molded product produced by the production method.

Background art

Conventionally, as a backlight device for a liquid crystal display, an edge light type method or a direct type method is used. For example, a general direct type backlight device includes a plurality of light sources arranged in parallel, a reflection plate that reflects light emitted from the light source, light from the light source and light reflected by the reflection plate. And a light diffusing plate for diffusing irradiation

[0003] The light diffusing plate used in such a direct type backlight device is often molded by an extrusion molding method, a casting method, an injection molding method, or the like. For example, Japanese Patent Application Publication No. 20 05-271306 discloses a method of forming a light diffusion plate by an injection molding method. In this method, a rectangular cavity surface is divided into predetermined rectangles, and a light diffusing plate is manufactured by using a mold in which a gate is provided at the center in the short direction from the intersection of diagonal lines of each rectangle. It is. According to such a method, since air does not easily accumulate in the cavity, there is an effect that it is possible to efficiently manufacture a high-quality light diffusing plate with less appearance defects due to burning or the like.

Disclosure of the invention

[0004] However, in the gate row in the short direction of the rectangular cavity surface, there are a mixture of a wide gate interval and a narrow gate interval, so that the pressure rises at a narrow gate interval. In some cases, the in-mold pressure could not be lowered sufficiently. Such a problem occurs not only in the light diffusion plate but also in other optical members such as a light guide plate and a reflection plate and other flat plate molded products.

[0005] An object of the present invention is to provide a method for producing a flat plate product capable of efficiently producing a high quality flat plate product while keeping the pressure inside the mold low, and a flat plate product obtained by this production method. It is to provide.

[0006] As a result of intensive studies by the present inventors in order to solve the above-mentioned problem, for example, when three gates in the vertical direction and four gates in the horizontal direction are arranged at equal intervals, three in the vertical direction. Out of the gates lined up, the resin is injected from the gate row (first gate row) along the lateral direction including the middle gate, and then the timing is shifted so that the gate rows on both sides of the first gate row (second gate row) We have found that high-quality flat plate molded products can be produced efficiently by suppressing the internal pressure of the mold by injecting force grease.

[0007] Also, there is provided a method for manufacturing a flat plate molded product capable of efficiently manufacturing a high quality flat plate molded product while suppressing the internal pressure when a plurality of gates are arranged at equal intervals in the vertical direction and the horizontal direction, respectively. I found it.

[0008] That is, according to the first aspect of the present invention, there is provided a method for manufacturing a resin-made flat plate molded article using an injection mold, wherein the mold is the flat plate molded article. A substantially rectangular cavity surface corresponding to the shape of the cavity surface is formed, and a fixed mold plate provided with a plurality of gates communicating with the cavity surface is provided, and the plurality of gates are substantially rectangular longitudinally of the cavity surface. When considering a grid having a vertical pitch L1 and a horizontal pitch L2 along the horizontal and horizontal directions, the substantially rectangular cavity surface is arranged at the position of the intersection of the grids. In the four outermost gates, which are the gates closest to each vertex, the distance LA1 to LA4 between each outermost gate and the nearest side among the lateral sides of the cavity surface is 120% to the pitch L1. 10% and each outermost gate and the cavity surface The distances LB1 to LB4 with the closest side among the vertical sides are 120% to 10% of the pitch L2, and the plurality of gates are a plurality of gates arranged in the vertical direction. The number of gate rows in at least one of the number of the vertical gate rows and the number of the horizontal gate rows as a plurality of horizontal gate rows comprising a vertical gate row and a plurality of gates arranged in the horizontal direction Is an odd number, and in the gate row in any direction where the odd number is present, the first gate row is a row including a plurality of gate rows and a central gate that is a gate closest to an intersection of diagonal lines of the cavity surface. A second gate row including two gate rows close to the first gate row, a third gate row including gate rows close to the gate rows constituting the second gate row, the n-1th gate Each gate row close to each gate row that makes up the row The n-th gate column that contains ( n is an integer greater than or equal to 2), and the first step of injecting the resin from the first gate row, and when the injection amount of the n-1 gate row force reaches a predetermined amount, the nth gate row A flat plate provided with an n-th step for ejecting the resin (when n has a value of 3 !, n stands for all values of 2 to k!) A method of manufacturing a molded article is provided.

[0009] As described above, in at least one direction, since an odd number of gate rows are provided at a predetermined pitch, the center gate row becomes the first gate row, and the gate closest to the first gate row. The second gate row, which is a row, will contain two gate rows, one on each side of the first gate row. In addition, there is one gate row that is the closest to each gate row force that constitutes the second gate row, so there are also two third gate rows. After that, there will be two gate rows for every nth gate row.

[0010] In the method for producing a flat molded product according to the first aspect of the present invention, for example, when the gate row has a number S3, the resin is fed from the central gate row (first gate row). A first step of injecting, and then a second step of injecting the resin from the gate rows (second gate rows) on both sides of the first gate row. If the number of gate rows is five, the first gate row force is also injected from the first step of injecting the resin, and then from each gate row (second gate row) on both sides of the first gate row. A second step of injecting the grease, and then a third step of injecting the grease from the closest gate row (third gate row) constituting each second gate row. In summary, if the number of gate columns is 2n-l (where n is an integer equal to or greater than 2), in the first aspect of the present invention, the first step, the second step,. Will be included.

[0011] According to the method for manufacturing a flat molded product according to the first aspect of the present invention, the first gate row including the central gate is formed in the order of the first gate row in the direction of the odd number of rows. As the second gate row, the timing of the resin injection is shifted in the order of this gate row, so that even if the gates are arranged approximately at the intersections of the lattice, there is no air pool in the cavity. It is possible to prevent appearance defects such as burning due to air accumulation. This makes it possible to produce high-quality flat plate products. In addition, since the plurality of gates are arranged substantially evenly in this way, it is possible to keep the internal pressure of the mold within which the pressure does not rise partially in the cavity. As described above, according to the present invention, a high-quality flat plate molded product can be manufactured more efficiently while keeping the in-mold pressure low. Here, the number of gate rows is, for example, 4 in the vertical direction, 3 in the horizontal direction, 3 in the vertical direction, 3 in the horizontal direction, 2 in the vertical direction, 3 in the horizontal direction, and 4 in the vertical direction. X can be 5 in the horizontal direction. Further, the direction of the odd number of columns may be either the vertical direction or the horizontal direction. However, the direction of the odd number of columns is preferably the longer one of the vertical direction and the horizontal direction.

[0013] Further, the distances LA1 to LA4 in the outermost gates may be substantially the same, and the distances LB1 to LB4 in the outermost gates may be substantially the same.

[0014] Further, according to the second aspect of the present invention, there is provided a method for producing a substantially rectangular flat plate molded article by injection molding a resin using an injection mold. The mold includes a movable mold plate and a fixed mold plate on which a substantially rectangular cavity surface corresponding to the shape of the flat plate molded product is formed and a plurality of gates communicating with the cavity surface are provided. The plurality of gates have a pitch in the first direction along the first side of the substantially rectangular shape of the cavity surface is L1, and the second direction in the second direction along the second side orthogonal to the first direction. When considering a lattice having a pitch of L2, the plurality of gates arranged at the intersections of the lattice and a plurality of first gate rows composed of a plurality of gates arranged along the first direction are arranged. A plurality of second gate rows composed of a plurality of gates arranged along the second direction. In the first gate row, the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the eleventh gate row and the twelfth gate row, and the two gates close to the eleventh gate row and the twelfth gate row. The rows are the 13th gate row and the 14th gate row, respectively. In the second gate row, the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the 21st gate row and the 22nd gate row. When the two gate rows close to the gate row and the 22nd gate row are respectively the second 3rd gate row and the 24th gate row, and each gate is expressed as (first gate row, second gate row), (13, 21), (11, 22), (12, 21), (14, 22) first group including gates (13, 22), (11, 21), (12, 22), (14, 21) a first step of injecting the resin from each gate included in any one of the second groups including each gate; When the injection amount in the first step reaches a predetermined amount, the second step of injecting the resin from each gate included in the other group and the injection amount in the second step become the predetermined amount. When And a third step of injecting the resin from each gate of the 23rd gate row and the 24th gate row.

[0015] In the method for producing a flat molded article according to the second aspect of the present invention, as the first step, resin is sprayed from each gate included in the first group or each gate included in the second group, In the second step, the resin is injected from each gate included in the second group or each gate included in the first group, and in the third step, the resin is injected from each gate of the 23rd gate row and the 24th gate row. Since the injection timing of the grease from each gate is shifted so as to inject the oil, even if the plurality of gates are arranged at the intersections of the lattice, there is no air pocket in the cavity. It is possible to prevent appearance defects such as burning due to air accumulation. For this reason, a high quality flat plate molded product can be manufactured. In addition, since the plurality of gates are arranged in a substantially uniform manner in this way, the mold pressure within the cavity where the pressure does not partially rise can be kept low. Therefore, it is possible to manufacture a high-quality flat plate molded product more efficiently while keeping the in-mold pressure low.

[0016] Further, according to the third aspect of the present invention, there is provided a method of manufacturing a substantially rectangular flat plate molded article by injection molding a resin using an injection mold. The mold includes a movable mold plate and a fixed mold plate on which a substantially rectangular cavity surface corresponding to the shape of the flat plate molded product is formed and a plurality of gates communicating with the cavity surface are provided. The plurality of gates have a pitch in the first direction along the first side of the substantially rectangular shape of the cavity surface is L1, and the second direction in the second direction along the second side orthogonal to the first direction. When considering a lattice having a pitch of L2, the plurality of gates arranged at the intersections of the lattice and a plurality of first gate rows composed of a plurality of gates arranged along the first direction are arranged. A plurality of second gate rows composed of a plurality of gates arranged along the second direction. In the first gate row, the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the eleventh gate row and the twelfth gate row, and the two gates close to the eleventh gate row and the twelfth gate row. The rows are the 13th gate row and the 14th gate row, respectively. In the second gate row, the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the 21st gate row and the 22nd gate row. The two gate rows close to the gate row and the 22nd gate row are the second gate row and the 24th gate row, respectively, and each gate is expressed as (first gate row, second gate row). The first group including the gates of (11, 22) and (12, 21), and one of the second groups including the gates of (11, 21) and (12, 22). A first step of injecting the resin from each gate included in the first step, and when the injection amount in the first step reaches a predetermined amount, the resin is injected from each gate included in the other group When the injection amount in the second step and the second step reaches a predetermined amount, the resin is discharged from each gate of the thirteenth gate row, the fourteenth gate row, the twenty-third gate row, and the twenty-fourth gate row. There is provided a method for producing a flat molded article including a third step of injecting.

[0017] In the method for manufacturing a flat molded product according to the third aspect of the present invention, as the first step, resin is sprayed from each gate included in the first group or each gate included in the second group, As the second step, grease is injected from each gate included in the second group or from each gate included in the first group, and as the third step, the thirteenth gate row, the fourteenth gate row, and the twenty-third gate row Since the timing of the injection of the resin from each gate is shifted so that the resin is injected from each gate of the 24th gate row, a plurality of gates may be arranged at the intersections of the lattice. In addition, air retention does not occur in the cavity, and appearance defects such as burning due to the air retention can be prevented. For this reason, a high quality flat plate molded product can be manufactured. In addition, since the plurality of gates are arranged substantially evenly in this way, it is possible to keep the internal pressure of the mold within which the pressure does not increase partially in the cavity. Accordingly, it is possible to manufacture a high-quality flat plate product more efficiently while keeping the in-mold pressure low.

[0018] Further, in the method for manufacturing a flat molded product according to the second and third aspects of the present invention, in the four outermost gates which are the gates closest to each vertex of the substantially rectangular shaped cavity surface, The distance LA1 to LA4 between each outermost gate and the nearest side of the cavity surface in the second direction is 120% to 10% of the pitch L1, and each outermost gate and the cavity surface. It is preferable that the distances LB1 to LB4 with the closest side among the sides in the first direction are 120% to 10% of the pitch L2.

[0019] Preferably, the distances LA1 to LA4 at the outermost gates are substantially the same, and the distances LB1 to LB4 at the outermost gates are substantially the same. According to the method for producing a flat plate molded article of the present invention, it is possible to satisfactorily inject grease into the vicinity of each apex of a substantially rectangular shaped cavity surface, and to produce a high-quality flat surface having no thickness unevenness. A plate molded product can be manufactured more efficiently.

[0020] Further, in the method for manufacturing a flat molded product according to the first to third aspects of the present invention, the number of the gates is N (pieces), and the depth of the cavity formed in the fixed mold is t. When the area of the cavity surface is S (mm ² ), it is preferable that the following formula (1) is satisfied.

[0021] (Equation 1)

(S / (t + 6)) X 10 ^-4 ≤ N ≤ (2S / t) X 10 " ⁴ ---(l)

Further, according to the fourth aspect of the present invention, it is possible to provide a flat molded product having no appearance defect manufactured by the method for manufacturing a flat molded product of the present invention. Examples of such flat plate molded products include optical members such as a light diffusing plate and a light guide plate.

Brief Description of Drawings

FIG. 1 is a plan view schematically showing a cavity surface formed on a fixed mold according to a first embodiment of the present invention.

FIG. 2 is a plan view for explaining the position of the gate formed on the cavity surface according to the first embodiment of the present invention.

FIG. 3 is a plan view of a cavity surface for explaining a method of manufacturing a light diffusing plate according to the first embodiment of the present invention.

FIG. 4 is a flowchart for explaining the procedure of the method for manufacturing the light diffusing plate according to the first embodiment of the present invention.

FIG. 5 is a plan view schematically showing a cavity surface formed on a fixed mold plate according to a second embodiment of the present invention.

FIG. 6 is a plan view for explaining the position of the gate formed on the cavity surface according to the second embodiment of the present invention.

FIG. 7 is a plan view of a cavity surface for explaining a method of manufacturing a light diffusing plate according to the second embodiment of the present invention.

FIG. 8 is a flowchart for explaining the procedure of a method for producing a light diffusing plate according to the second embodiment of the present invention.

FIG. 9 is a diagram for explaining a state of resin flow when manufacturing a light diffusing plate according to a second embodiment of the present invention. FIG. 10 is a diagram for explaining a state of resin flow when manufacturing a light diffusing plate according to a second embodiment of the present invention.

FIG. 11 is a diagram for explaining a state of resin flow when manufacturing a light diffusing plate according to a second embodiment of the present invention.

FIG. 12 is a diagram for explaining gate opening / closing timings when the number of gates formed on the stationary mold plate according to the second embodiment of the present invention is 6 × 8.

FIG. 13 is a view for explaining the state of resin flow when manufacturing a light diffusing plate according to a third embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 15 is a plan view schematically showing a cavity surface of a fixed mold in Comparative Example 2 as a conventional technique.

FIG. 16 is a plan view schematically showing the cavity surface of the fixed mold in Comparative Example 3 as a prior art.

FIG. 17 is a plan view schematically showing the cavity surface of the fixed mold plate in Comparative Example 4 as a conventional technique.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, with reference to the drawings, a method for producing a flat resin molded product made of resin using the injection mold according to the first embodiment of the present invention will be described. First, the injection mold used in the first embodiment will be described. An injection mold is composed of a fixed mold (fixed mold plate) and a movable mold (movable mold plate), and injects grease into the cavity that is the gap between the fixed mold and the movable mold. Then, for example, a light diffusion plate that is a flat plate molded product is manufactured.

[0024] Here, a gas vent is provided at the outer peripheral edge of the injection mold for releasing air in the cavity at the time of injection molding. The fixed mold can be equipped with a hot runner or cold runner. Moreover, a vacuum drawing hole for releasing air in the cavity or the like can be provided in the fixed mold or the movable mold.

[0025] The depth of the cavity is preferably 0.1 mm to 15. Omm, more preferably 0.2 mm to 5. Omm. 0.5 nm! ~ 3. More preferably, it is Omm. The key The depth of the cavity substantially coincides with the thickness of the obtained flat plate molded product.

FIG. 1 is a plan view schematically showing a cavity surface formed on a fixed mold. As shown in FIG. 1, the cavity surface 10 is formed in a substantially rectangular shape. In the substantially rectangular shaped cavity surface 10, the rectangular vertex is 10A ~: L0D, the vertical side connecting vertex 10A and vertex 10B is 11A, and the vertical side connecting vertex IOC and vertex 10D is 11B, the horizontal side connecting vertex 10A and vertex 10C is 12A, and the horizontal side connecting vertex 10B and vertex 10D is 12B. The vertical direction is the vertical direction in FIG. 1, and the horizontal direction is the left-right direction in FIG.

[0027] The diagonal length of the cavity surface 10 (distance between vertex 10A and vertex 10D, distance between vertex 10B and vertex 10C) is preferably 400 mm or more, more preferably 650 mm or more. . According to the manufacturing method according to an embodiment of the present invention to be described later, even if the diagonal length is larger than the numerical value, a flat plate molded product with less thickness unevenness can be efficiently manufactured.

[0028] Here, as an aspect of the substantially rectangular shape of the cavity surface, for example, (1) when the entire cavity surface is rectangular, (2) the entire cavity surface is a rectangular main body, and the main body The peripheral edge portion is formed in an arbitrary shape, and the entire cavity surface is not a rectangular shape.

[0029] The vertical length of the cavity surface 10 (the length of the sides 11A and 11B) and the length in the horizontal direction

(Length of side 12A and side 12B) is not particularly limited. For example, the length in the vertical direction and the length in the horizontal direction are described as 740mm in length X 430mm in width and 1,020mm in length X 600mm in width. It can be. The cavity surface 10 is usually formed so that the length in the horizontal direction is larger than the length in the vertical direction, but the length in the vertical direction and the length in the horizontal direction may be substantially the same.

The fixed mold is formed with a plurality of gates (pinpoint gates) 20 communicating with the cavity surface 10. Here, FIG. 2 is a schematic diagram for explaining the position of the gate 20 on the cavity surface 10. As shown in FIG. 2, each gate 20 consists of a vertical line A along the vertical side キ ΙΑ (Ι ΙΒ) of the cavity surface 10 and a horizontal line B along the horizontal side 12A (12B). Is considered at the position of the intersection P of the lattice. This lattice is The vertical pitch (the pitch between the gates 20 arranged in the vertical direction) is L1, and the horizontal pitch (the pitch between the gates 20 arranged in the horizontal direction) is L2. In other words, the plurality of gates are formed at substantially equal intervals along the vertical direction and the horizontal direction of the cavity surface 10. Here, “substantially uniform intervals” means that each interval falls within an error range of about 10% with respect to an average interval obtained by averaging all intervals in a certain direction. The error range is preferably within a range of about 5%, more preferably within a range of about 1%. As described above, since the gates 20 are substantially evenly arranged, the pressure inside the mold can be kept low, and the one with a small mold clamping force can be used. Specifically, for example, when the dimension of the cavity surface 10 is 740 mm long by 430 mm wide, the pitch L1 in the vertical direction can be 143.3 mm and the pitch L2 in the horizontal direction can be 185 mm.

Further, as shown in FIG. 2, out of the plurality of gates 10, the gates 20A to 20D are the outermost gates 20A to 20D, which are closest to each vertex 10A to LOD. Here, the distance LA1 between the lateral side 12A closest to the outermost gate 20A and the outermost gate 20A is 120% to 10%, preferably 100% to 20% of the pitch L1. The distance LB1 between the vertical side 11A closest to the outermost gate 20A and the outermost gate 20A is 120% to 10%, preferably 100% to 20% of the pitch L2.

[0032] Further, in the outermost gate 20B, the distance LA2 between the lateral side 12B and the outermost gate 20B where the outermost gate 20B force is closest is 120% to 10% of the pitch L1, and preferably 100 % To 20%. The distance LB2 between the vertical side 11A closest to the outermost gate 20B and the outermost gate 20B is 120% to 10%, preferably 100% to 20% of the pitch L2.

[0033] In the outermost gate 20C, the distance LA3 between the lateral side 12A and the outermost gate 20C where the outermost gate 20C force is closest is 120% to 10%, preferably 100% to 20% of the pitch L1. %. Further, the distance LB3 between the vertical side 11B and the outermost gate 20C closest to the outermost gate 20C force is 120% to 10%, preferably 100% to 20% of the pitch L2.

[0034] In the outermost gate 20D, the distance LA4 between the lateral side 12B and the outermost gate 20D where the outermost gate 20D force is closest is 120% to 10% of the pitch L1, preferably 100. % To 20%. Further, the distance LB4 between the vertical side 1 IB closest to the outermost gate 20D force and the outermost gate 20D is 120% to 10%, preferably 100% to 20% of the pitch L2.

Note that the pitch L1 can be an average value of the intervals. Similarly, the pitch L2 can be an average value of each interval.

Here, the distances LA1 to LA4 are preferably substantially equal to each other. The distances LB1 to LB4 are preferably substantially equal to each other. Note that “substantially equal” means that the distances LA1 to LA4 have an error of 10% or less with respect to the average distance obtained by averaging the distances LA1 to LA4. The error is preferably 5% or less, more preferably 1% or less. By setting it as such a structure, it can suppress that thickness nonuniformity arises in the obtained flat plate molded article.

[0037] In the injection mold used in the present embodiment, the number of installed gates N (pieces) is determined when the depth of the cavity is t (mm) and the area of the cavity is S (mm ² ). It is preferable that the following mathematical formula (1) is satisfied.

[0038] (Equation 1)

(S / (t + 6)) X 10 ^-4 ≤ N ≤ (2S / t) X 10 " ⁴ ---(l)

If the number of gates is less than the preferred range, there is a risk that unevenness in the thickness of the flat plate molded product will occur due to an increase in the flow distance of the resin within the cavity. Further, when the number of gates is larger than the preferable range, it may be difficult to manufacture a mold. For this reason, by setting the number of gates within the preferred range, it is possible to easily form a high-quality flat plate molded product.

As described above, since the plurality of gates 20 are arranged on the intersection P of the lattice, as shown in FIG. 1, the plurality of gates 20 are connected to the vertical gate row 21 which is a vertical gate row. And horizontal gate row 22 which is a horizontal gate row. In the present embodiment, the number of vertical gate rows 21 is several, and the number of horizontal gate rows 22 is three (odd number). The number of gates 20 constituting the vertical gate row 21 is three, and the number of gates 20 constituting the horizontal gate row 22 is four.

Next, the resin that is a constituent material of the flat plate molded product will be described. Used in this embodiment Examples of the coconut resin include alicyclic resin having an alicyclic structure, a copolymer of an aromatic vinyl monomer and an alkyl ester (meth) acrylate ester, methallyl rosin, polycarbonate, polystyrene, acrylonitrile. -Styrene copolymer resin, ABS resin, and polyether sulfone. Among these, a resin having an alicyclic structure, a methacrylic resin, and a copolymer of an aromatic butyl monomer and a (meth) acrylic acid alkyl ester monomer can be suitably used. A resin having a cyclic structure can be particularly preferably used.

[0041] Since the resin having an alicyclic structure has good fluidity of the molten resin, it can be filled with mold cavity at a low injection pressure, and has extremely low hygroscopicity, so it has excellent dimensional stability. Since the specific gravity that does not cause warpage in the flat plate molded product is small, the flat plate molded product can be reduced in weight. In addition, rosin having an alicyclic structure has an advantage that weld lines are less likely to occur.

[0042] A resin having an alicyclic structure is a resin having an alicyclic structure in a main chain or a side chain. Among these, rosin having an alicyclic structure in the main chain is particularly suitable because it has good mechanical strength and heat resistance. The alicyclic structure is preferably a saturated cyclic hydrocarbon structure, and its carbon number is preferably 4 to 30, more preferably 5 to 20, and more preferably 5 to 15. More preferably. The proportion of the repeating unit having an alicyclic structure in the alicyclic resin having an alicyclic structure is preferably 50% by weight or more, more preferably 70% by weight or more, and more preferably 90% by weight or more. More preferably.

[0043] Examples of rosins having an alicyclic structure include, for example, ring-opening polymers or ring-opening copolymers of norbornene monomers or hydrogenated products thereof, addition polymers or additions of norbornene monomers. Copolymer or hydrogenated product thereof, polymer of monocyclic cyclic olefin monomer or hydrogenated product thereof, polymer of cyclic conjugation monomer or hydrogenated product thereof, vinyl alicyclic carbonization Polymer or copolymer of hydrogen monomer or hydrogen additive thereof, polymer of vinyl aromatic hydrocarbon monomer or hydrogenated product of unsaturated bond part containing aromatic ring of copolymer And so on. Among these, hydrogenated products of norbornene-based monomer polymers and hydrogenated products of unsaturated bonds including aromatic rings of vinyl aromatic hydrocarbon-based monomer polymers have mechanical strength and strength. Since it is excellent in heat resistance, it can be used particularly suitably. The methacrylic resin is suitable for an optical member because it is excellent in transparency, tough and hardly cracks. Examples of the methacrylic resin include a methacrylic resin molding material containing 80% or more of a methyl methacrylate polymer defined in Japanese Industrial Standard JIS K 6717. Among methacrylic resins stipulated in this standard, methacrylic resin with a Vicat soft spot temperature of 96-100 ° C and a melt rate of 8 to 16 with a specified classification code of 100-120 has moderate fluidity and strength. Therefore, it can be suitably used.

[0045] The aromatic bulle monomer constituting the copolymer of the aromatic vinyl monomer and the (meth) acrylic acid alkyl ester is an aromatic vinyl monomer and a derivative thereof, such as styrene. , A-methylstyrene, m-methylstyrene, p-methylstyrene, 0-chlorostyrene, and P-chlorostyrene. Examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms. As the (meth) acrylic acid alkyl ester, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate can be suitably used. A copolymer of an aromatic butyl monomer and a (meth) acrylic acid alkyl ester is a copolymer of 20 to 60% by weight of an aromatic butyl monomer and 40 to 80% by weight of a (meth) acrylic acid alkyl ester. It is preferably a coalescence. In addition, (meth) acrylic acid means metatalic acid and acrylic acid, and (meth) acrylic means methacryl and acrylic.

[0046] In the present embodiment, as the resin, a mixture containing a thermoplastic elastomer or an additive can be used as necessary. Examples of the thermoplastic elastomer include polybutadiene, a styrene-butadiene block copolymer and a hydrogenated carotenate thereof, and a styrene-isoprene block copolymer and a hydrogenated product thereof. Examples of the additives include light diffusing agents, antioxidants, ultraviolet absorbers, light stabilizers, colorants such as dyes and pigments, lubricants, plasticizers, antistatic agents, and fluorescent whitening agents. it can. Examples of the light diffusing agent include a polystyrene polymer, a polysiloxane polymer, or fine particles made of a crosslinked product thereof, (meth) acrylic resin, fluorine resin, barium sulfate, calcium carbonate, silica, and talc. Can be mentioned. Among these, polystyrene-based polymers, polysiloxane-based polymers or their cross-linked products The fine particles are particularly suitable because they have good dispersibility, excellent heat resistance, and no yellowing during molding.

[0047] The blending amount of the thermoplastic elastomer is usually 0.01 wt% to 50 wt%, preferably 0.05 wt% to 30 wt%. Moreover, the compounding quantity of the said additive is 0.01 to 30 weight% normally, Preferably it is 0.05 to 20 weight%. When a light diffusing agent is mixed as a compounding agent, the particle size of the light diffusing agent is usually 0.5 / z m to: LOO / z m in terms of average particle size, and preferably 0.5 m to 80 m.

[0048] Next, a method for producing a light diffusion plate, which is a flat resin molded product made of resin, using the injection mold according to the first embodiment will be described. FIG. 3 is a plan view of a cavity surface for explaining a method of manufacturing a light diffusing plate. FIG. 4 is a flowchart for explaining the procedure of the method of manufacturing the light diffusing plate.

As shown in FIG. 3, the horizontal gate row 22 includes three horizontal gate rows 22A, 22B, and 22C. Of these horizontal gate rows 22A, 22B, and 22C, the row that includes the gates 20S and 20T that are closest to the intersection of the diagonal lines of the cavity surface 10 is defined as the first horizontal gate row X, and this first horizontal gate row. Two gate rows close to the row are designated as the second horizontal gate row Y. In the present first embodiment, the lateral gate row 22B is the first lateral gate row X, and the lateral gate row 22A and the lateral gate row 22C that are substantially the same distance from the first lateral gate row X are Second horizontal gate row Y.

First, as shown in FIG. 4, the mold for injection molding is clamped at a predetermined pressure using a saddle mold clamping device (not shown) (step Sl). Next, the gate of the first horizontal gate row X is opened, and the resin is injected from the gate of the first horizontal gate row X at a constant injection rate (step S2: first step). At this time, the resin injected into the cavity also flows out with a force corresponding to the first gate row X directed toward the outer peripheral side of the cavity surface 10. The injection amount of the resin can be grasped by the injection time since the injection rate (injection speed) is constant.

[0051] Next, it is determined whether or not the force with which the injection amount from the gates of the first horizontal gate row X becomes a predetermined amount (step S3). Specifically, this determination may be performed based on, for example, the injection time. If necessary, the resin injected from the gates of the first gate row X is changed into the first horizontal gate row X and the second horizontal gate. This may be done by checking whether or not the current has flown to about half the distance of row Y.

[0052] If the injection amount of the resin does not reach the predetermined amount, step S2 is repeated. Oil injection When the amount reaches the planned amount, the gate of the first horizontal gate row X is opened while the gate of the first horizontal gate row X is opened, and the gate of the first horizontal gate row X and the second horizontal gate row are opened. The resin is injected from the Y gate at the injection rate (step S4: second step).

Next, it is determined whether or not the injection amounts from the gates of the first lateral gate row X and the gates of the second lateral gate row Y have become predetermined amounts as described above (step S5). If the injection amount of the resin does not reach the expected amount, repeat step S4. When the resin injection amount reaches the predetermined amount, the gates of the first horizontal gate row X and the second horizontal gate row Y are closed, and the injection from the gates of these gate rows X and Y is stopped. (Step S6). Thereafter, the injection mold is cooled (step S7), and the mold force is taken out of the light diffusion plate (step S8). As described above, one cycle of manufacturing the light diffusion plate is completed.

[0054] In step S6, the timing of closing the gate is usually performed when the injection amount of the resin reaches a predetermined amount. For example, the state of filling the surface of the molded product is observed, and this is done. It may be performed when the state of filling becomes better. The light diffusing plate is manufactured by repeating such a cycle a plurality of times.

[0055] According to the first embodiment, in the direction of the odd number of columns, the first gate column including the center side gate thereof is used, and the second gate column is arranged in the order closer to the first gate column. Since the injection timing of the resin is shifted in the order of the rows, even if the multiple gates are arranged at the intersections of the grid, there is no air pool in the cavity, and there is no burning in the air pool. It is possible to prevent the appearance defect from occurring. For this reason, high quality flat plate molded products can be manufactured. In addition, since the plurality of gates are arranged substantially evenly in this way, it is possible to keep the mold internal pressure within the cavity where the pressure does not partially rise low. Therefore, it is possible to more efficiently manufacture a high-quality flat plate molded product while keeping the in-mold pressure low.

[0056] Further, according to the first embodiment, the following effects can be obtained. Since the gate 20 is arranged on the cavity surface 10 so that the distance between the adjacent gates 20 is substantially constant, the mold internal pressure is approximately the same at any position within the cavity. For this reason, since the pressure inside the mold can be kept low, a mold clamping device having a small mold clamping force can be used, and space saving can be achieved.

[0057] The first lateral gate X and the second lateral gate row Y are divided into the center side of the cavity surface 10. After injecting the grease from the gate 20 of the lateral gate row X, the injection timing was shifted so that the gate 20 force of the lateral gate row Y outside also injects the grease. However, there is no air pocket in the cavity. For this reason, appearance defects such as burning caused by air accumulation do not occur in the obtained flat plate molded product, so that a high-quality light diffusion plate can be efficiently produced.

Note that the present invention is not limited to the above-described embodiment! For example, in the above-described embodiment, the number of vertical gate rows X the number of horizontal gate rows is 4 X 3. However, if the number of gate rows in at least one of the vertical direction and the horizontal direction is an odd number, the gate rows The number of is not limited to the above number. Further, the size of the cavity surface is not limited to the above size. Moreover, in the said embodiment, although the obtained flat plate molded article was used as the light diffusing plate, it may be used as optical members, such as a light-guide plate, and may be used as members other than an optical use.

[0059] In the above embodiment, the injection timing is adjusted based on the horizontal gate row 22. If the number of the vertical gate rows 21 is an odd number, the injection timing is adjusted based on the vertical gate rows 21. May be. Also, the gate row for timing adjustment can be a gate row along the long side, which is the long side, and the gate row along the vertical direction, which is the short side! / ,.

[0060] The distances LB1 to LB4 in the horizontal direction are preferably about 30% to 70% of the distance L2 in the horizontal direction (for example, the average distance). The length is 45% to 55%. More preferably, it is 49% to 51%. The vertical distances LA1 to LA4 are preferably about 30% to 70% of the vertical distance L1, and more preferably 45% to 55%. More preferably, it is 49% to 51%. According to such a configuration, it is possible to form a high-quality flat plate molded product in which uneven thickness and poor appearance are further improved by allowing the molten resin to flow more suitably.

[0061] Next, a method for producing a flat resin molded product made of resin using the injection mold according to the second embodiment of the present invention will be described with reference to the drawings.

[0062] Note that the second embodiment has the first implementation described above in terms of the arrangement and number of gates provided in the injection mold, the timing of opening and closing the gate when manufacturing a flat molded product, and the like. This is different from the method for producing the injection mold according to the embodiment and the flat resin molded product made of resin, but otherwise the same injection mold as used in the first embodiment. Is used to manufacture a flat molded product. Therefore, in the following, detailed description of the parts common to the first embodiment will be omitted, and only different parts will be described in detail. Further, the same components as those in the first embodiment will be described using the same reference numerals.

[0063] The injection mold used in the second embodiment includes a fixed mold plate and a movable mold plate, as in the first embodiment described above, and includes a fixed mold plate and a movable mold plate. A cavity is formed by the gap, and the depth of the cavity substantially matches the thickness of the obtained flat plate molded product.

FIG. 5 is a plan view schematically showing the cavity surface formed on the fixed mold plate, and corresponds to FIG. 1 in the first embodiment. As shown in FIG. 5, the cavity surface 10 is formed in a substantially rectangular shape, and the diagonal length is preferably 400 mm or more, more preferably 650 mm or more. The vertical length and the horizontal length of the cavity surface 10 are not particularly limited, and are usually formed so that the horizontal length is larger than the vertical length. And the length in the horizontal direction may substantially coincide with each other.

FIG. 6 is a schematic diagram for explaining the position of the gate 20 on the cavity surface 10, and corresponds to FIG. 2 in the first embodiment. As shown in FIG. 6, a plurality of gates 20 communicating with the cavity surface 10 are formed on the fixed template, and each of the gates 20 has a longitudinal pitch L1 and a lateral pitch of the cavity surface 10. L2 is formed at substantially equal intervals along the vertical direction and the horizontal direction. In addition, as shown in FIG. 6, the gates closest to each vertex 10A-: L0D are the outermost gates 20A-20D, respectively, and the distance LA1 between each outermost gate 20A-20D and the lateral side with respect to each of them is LA1. ˜LA4 is 120% to 10% of L1, preferably 100% to 20%. Further, each outermost gate 20A to 20D, the distance LB1~LB4 ί the longitudinal sides for each or a 120-10 ^_0/0 of L2, preferably I or 100 ⁰ / _0-20 ^_0/0 is there.

[0066] In the injection mold, it is preferable that the number of gates to be installed satisfies Equation (1), as in the first embodiment.

In the second embodiment, since the plurality of gates 20 are arranged on the intersections of the lattices, as shown in FIG. 7, the plurality of gates 20 are arranged in the vertical direction as a vertical gate row. Gate column They can be classified into (11th to 14th gate rows) and horizontal gate rows (21st to 24th gate rows), which are lateral gate rows. In the second embodiment, the number of vertical gate rows is four (even numbers), and the number of horizontal gate rows is even (even numbers). The number of gates 20 constituting the vertical gate row is four, and the number of gates 20 constituting the horizontal gate row is four.

[0068] It should be noted that the resin that is a constituent material of the flat molded product uses the same resin as that used in the first embodiment, even in the second embodiment. Therefore, detailed description is omitted.

[0069] Next, a method for producing a light diffusing plate, which is a flat resin molded product made of resin, using the above-described injection molding die will be described. FIG. 8 is a flowchart for explaining the procedure of the method of manufacturing the light diffusing plate.

[0070] As shown in FIG. 7, in the vertical gate row (first gate row), the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the 11th gate row and the 12th gate row, and this 11th gate row. The two gate rows close to the twelfth gate row are the 13th gate row and the 14th gate row, respectively. In the horizontal gate row (second gate row), the two gates closest to the intersection of the diagonals of the cavity surface The gates are the 21st gate row and the 22nd gate row, and the two gate rows close to the 21st gate row and the 22nd gate row are the 23rd gate row and the 24th gate row, respectively. 1 gate row, 2nd gate row).

First, as shown in FIG. 8, the mold for injection molding is clamped at a predetermined pressure using a mold clamping device (not shown) (step S11). Next, open each gate of the first group, that is, (13, 21), (11, 22), (12, 21), (14, 22) gates, and make certain projections from these gates. The resin is injected at a rate (step S12: first step). At this time, the grease injected into the cavity flows out from each gate of the first group to the outer peripheral side of the cavity surface 10 as shown in FIG. The injection amount of the resin can be grasped by the injection time since the injection rate (injection speed) is constant.

[0072] Next, it is determined whether or not the injection amount from each gate of the first group has become a predetermined amount (step S13). Specifically, this determination may be performed based on, for example, the injection time. 1S If necessary, the resin injected from each gate of the first group is half the distance to the gate of the second group described later. You can do it depending on whether it has flowed to a certain level. Grease If the output amount has not reached the planned amount, the process of step S12 is continued. When the injection amount of the resin reaches the planned amount, each gate of the second group, that is, (13, 22), (11, 21), (12, 22), with the gates of the first group open. ), (14, 21) are opened, and the resin is injected from the gates of the first group and the second group at the injection rate (step S14: second step). FIG. 10 is a view showing a state in which the resin is injected from each gate of the first group and the second group. In this figure, the circles indicating the range of the grease flowing out from each gate of the first group overlap each other, and the circles indicating the range of the grease flowing out from each gate of the first group are the cavity surface. There is a part that protrudes. In fact, in this part, the fat flows in the direction of the arrow shown in the figure so as to compensate for the slow part of the fat flow. And, as shown by the wavy line in FIG. 11, the resin is filled in the lateral direction of the cavity.

[0073] Next, it is determined whether or not the injection amount from each gate of the second group has become a predetermined amount (step S15). If the injection amount of the resin does not reach the expected amount, continue the process of step S14. When the injection amount of the resin reaches a predetermined amount, each gate of the _third group, that is, each of the 23rd gate row and the 24th gate row is left with the gates of the first group and the second group being opened. Gate ((13, 23), (11, 23), (12, 23), (14, 23), (13, 24), (11, 24), (12, 24), (14, 24) Each gate) is opened, and the resin is injected at the injection rate from the gates of the first group to the third group (step S16: third step).

Next, it is determined whether or not the injection amount force from each gate of the third group has become a predetermined amount (step S17). If the injection amount of the resin does not reach the expected amount, continue the process of step S16. When the injection amount of the resin reaches the predetermined amount, the gates of the first group to the third group are closed, and the injection from these gates is stopped (step S18). Thereafter, the injection mold is cooled (step S19), and the mold force light diffusion plate is taken out (step S20). As described above, one cycle of manufacturing the light diffusion plate is completed.

[0075] In the process of step S18, the timing for closing the gate is normally performed when the amount of the resin spray reaches a predetermined amount. Observation may be made when this filling state becomes good. The light diffusing plate is manufactured by repeating such a cycle a plurality of times. In the second embodiment described above, the number of vertical gate rows × the number of horizontal gate rows is 4 × 4. If the number of vertical and horizontal gate rows is an even number, the number of gate rows The number is not limited to the number. FIG. 12 is a diagram for explaining the timing of opening the gate when the number of vertical gate rows X the number of horizontal gate rows is 6 x 8. In this case, the resin is injected from each gate included in the first group in the first process, and the resin is injected from each gate included in the first group and the second group in the second process. Alternatively, in the first step, the resin is injected from each gate included in the second group, and in the second step, the resin is injected from each gate included in the first group and the second group. After that, the gates included in the horizontal gate rows closest to the first group and the second group are opened to inject the resin, and further, the gates included in the outer horizontal gate rows are opened to open the resin. Inject.

[0077] Next, the third embodiment, which is another manufacturing method for manufacturing a light diffusing plate, which is a flat resin molded product made of resin, using the injection mold according to the second embodiment described above. Is explained. The processing procedure is the same as the procedure in the second embodiment shown in FIG. 8, and will be described with reference to FIG.

First, as shown in FIG. 8, the mold for injection molding is clamped at a predetermined pressure using a mold clamping device (not shown) (step S 11). Next, as shown in FIG. 12, each gate of the first group, that is, each gate of (11, 22) and (12, 21) shown in FIG. 13 is opened, and a constant injection rate is obtained from these gates. In step S12, the resin is injected. At this time, the resin injected into the cavity flows out from the gates of the first group toward the outer peripheral side of the cavity surface 10. Here, in FIG. 13, the range of the spread of the resin injected from each gate of the first group is indicated by a solid circle. The injection amount of the resin can be grasped by the injection time since the injection rate (injection speed) is constant.

Next, it is determined whether or not the injection amount from each gate of the first group has become a predetermined amount (step S13). Specifically, for example, this determination may be performed based on the injection time. If necessary, the resin injected from each gate of the first group flows to a position about half the distance from the adjacent gate. It may be done depending on whether or not it is correct. If the injection amount of the resin does not reach the expected amount, continue the process of step S12. The injection amount of sallow reaches the planned amount In this case, as shown in FIG. 13, with the gates of the first group open, the gates of the second group, ie, (11, 21), (12, 22) shown in FIG. The gate is opened, and the resin is injected from the gates of the first group and the second group at the injection rate (step S14: second step). Here, in FIG. 13, the range of spread of the resin injected from each gate of the second group is indicated by a dotted circle.

[0080] Next, it is determined whether or not the injection amount force from each gate of the second group is equal to the predetermined amount (step S15). If the resin injection amount has not reached the expected amount, continue with step S14. When the injection amount of the resin reaches the predetermined amount, the gates of the third group, that is, the gates of the thirteenth group as shown in FIG. Each gate of the row, the 14th gate row, the 23rd gate row and the 24th gate row ((13, 23), (13, 21), (13, 22), (13, 24), (14, 23), (14, 21), (14, 22), (14, 24), (11, 23), (12, 23), (11, 24), (12, 24) gates)) The resin is injected from the gates of the first group to the third group at the injection rate (step S16: third step).

[0081] Next, it is determined whether or not the injection amount from each gate of the third group has become a predetermined amount (step S17). If the injection amount of the resin does not reach the expected amount, continue the process of step S16. When the injection amount of the resin reaches the predetermined amount, the gates of the first group to the third group are closed, and the injection from these gates is stopped (step S18). Thereafter, the injection mold is cooled (step S19), and the mold force light diffusion plate is taken out (step S20). As described above, one cycle of manufacturing the light diffusion plate is completed.

[0082] In the process of step S18, the timing for closing the gate is normally performed when the amount of the resin spray reaches a predetermined amount. Observation may be made when this filling state becomes good. The light diffusing plate is manufactured by repeating such a cycle a plurality of times.

[0083] In the third embodiment, the number of vertical gate rows x the number of horizontal gate rows is 4 x 4. However, if the number of vertical and horizontal gate rows is an even number, the number of gate rows The number is not limited to the number. In that case, after controlling the injection timing of 4 x 4 gates by the above-mentioned method, the outer gates of the cavity are opened sequentially and the resin is injected. That is, The gates are opened sequentially from the inside to the outside.

[0084] According to each of the second and third embodiments described above, as the first step, the resin is injected from each gate included in the first group or each gate included in the second group, and the second step As a third step, resin is injected from each gate included in the second group or each gate included in the first group, and as a third step, the resin is injected from each gate of the 23rd gate row and the 24th gate row. The injection timing of the resin from each gate is shifted, or as the first step, the resin is injected from each gate included in the first group or each gate included in the second group, As the second step, the resin is injected from each gate included in the second group or from each gate included in the first group, and as the third step, the thirteenth gate row, the fourteenth gate row, the twenty-third gate row and the second gate row Injecting grease from each gate in the 24 gate row As described above, the injection timing of the resin from each gate is shifted, so even if a plurality of gates are arranged at the intersections of the lattice, there is no air pool in the cavity, and It is possible to prevent appearance defects such as burning. For this reason, a high quality flat plate molded product can be manufactured. In addition, since the plurality of gates are arranged substantially evenly in this way, it is possible to keep the mold internal pressure within the cavity that prevents the pressure from partially rising. Accordingly, it is possible to manufacture a high-quality flat plate product more efficiently while keeping the in-mold pressure low.

[0085] Further, according to the second and third embodiments described above, the following effects are obtained. Since the gate 20 is arranged on the cavity surface 10 so that the distance between the adjacent gates 20 is substantially constant, the mold internal pressure is approximately the same at any position within the cavity. For this reason, since the mold internal pressure can be kept low, a mold clamping device with a small mold clamping force can be used, and space saving can be achieved. Also, the gates were divided into the first group to the third group, and the injection timing was shifted so that the grease was emitted from each gate 20 in the order of the first group, the second group, and the third group. Therefore, even if the gates 20 are arranged substantially evenly, there is no air pool in the cavity. For this reason, the obtained flat plate molded product does not suffer from appearance defects such as burning caused by air accumulation, so that a high-quality light diffusion plate can be efficiently manufactured.

[0086] In each of the second and third embodiments described above, the resin is injected from each gate included in the first group in the first step, and included in the second group in the second step. The grease is injected from each gate, but in the first process, the resin is injected from each gate included in the second group, and in the second process, the resin is injected from each gate included in the first group. You may make it do.

In the second and third embodiments described above, the size of the cavity surface is not limited to the above size. In each of the above-described second and third embodiments, the obtained flat plate molded product is a light diffusion plate, but may be an optical member such as a light guide plate, or may be a member other than an optical application.

[0088] In each of the second and third embodiments described above, each of the horizontal distances LB1 to LB4 is approximately 30% to 70% of the horizontal distance L2 (for example, the average distance). It is more preferable that the length is 45% to 55%, and it is more preferable that the length is 49% to 51%. The vertical distances LA1 to LA4 are preferably about 30% to 70% of the vertical distance L1, and more preferably 45% to 55%. More preferably, it is 49% to 51%. According to such a configuration, a high quality flat plate molded product with improved thickness unevenness and appearance defect can be formed by flowing the molten resin more suitably.

Next, a liquid crystal display device including the light diffusing plate manufactured according to each of the above embodiments will be described. FIG. 14 is a diagram illustrating a configuration of the liquid crystal display device. The liquid crystal display device 30 includes a pair of liquid crystal substrates 31 disposed opposite to each other, a liquid crystal panel including a liquid crystal layer 32 sandwiched between the pair of liquid crystal substrates 31, and a pair of polarizing plates disposed so as to sandwich the liquid crystal panel. A light plate 33, a direct type backlight 34 that illuminates the LCD panel with a back force, and a liquid crystal panel and a direct type backlight 34 are arranged between the liquid crystal panel and the direct type backlight 34 to make light uniform, diffuse light, or collect light. An optical film 35 having a function of illuminating and a light diffusion plate 36 manufactured by the manufacturing method according to each of the above-described embodiments are provided. Here, the direct type backlight 34 is provided with a plurality of lamps 37 and a reflector 38 that are also cold cathode fluorescent lamps and the like.

[0090] According to the liquid crystal display device according to this embodiment, since the light diffusion plate 36 manufactured by the manufacturing method according to the above-described embodiment is provided, the liquid crystal panel can be well illuminated. I'll do it.

[0091] This disclosure relates to Japanese Patent Application No. 2006-34655 filed on February 13, 2006 and All of which disclosure is expressly incorporated herein by reference in relation to the subject matter contained in Japanese Patent Application No. 2006-225259 filed August 22, 2006. Example

Next, the present invention will be described in more detail with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

[0093] <Production Example 1 (Production of norbornene polymer)>

500 parts by weight of dehydrated cyclohexane, 0.82 parts by weight of 1-hexene, 0.15 parts by weight of dibutyl ether and 0.30 parts by weight of triisobutylaluminum are thoroughly dried at room temperature and placed in a nitrogen pressure-substituted stainless steel pressure vessel. After mixing, while maintaining the temperature at 45 ° C, 170 parts by weight of tricyclo [4.3.0.1 ^{2 5} ] deca-3,7-gen (dicyclopentagen, hereinafter abbreviated as “DCP”) and 8-ethylidene-tetracyclo [4.4.0.1 ² ' ⁵ .1 ⁷ · ¹⁰ ] -dode force-3-ene (ethylidenetetracyclododecene, hereinafter abbreviated as “ETD”) 30 parts by weight and hexasalt-tungsten (0.7 wt% toluene) Solution) 30 parts by weight were continuously added and polymerized over 2 hours. To the polymerization solution, 1.06 parts by weight of butyldaricidyl ether and 0.52 parts by weight of isopropyl alcohol were added to inactivate the polymerization catalyst, and the polymerization reaction was stopped.

Next, with respect to 100 parts by weight of the reaction solution containing the obtained ring-opening polymer, 270 parts by weight of cyclohexane was added, and a nickel-alumina catalyst (JGC) was added as a hydrogenation catalyst. 5 parts by weight, pressurized to 5 MPa with hydrogen, heated to 200 ° C with stirring and then reacted for 4 hours, containing 20% by weight of DCPZETD ring-opening polymer hydrogenated product A reaction solution was obtained. After removing the hydrogenation catalyst by filtration, 0.1 part by weight of a phenol-based antioxidation agent per 100 parts by weight of the hydrogenated product is pentaerythrityl-tetrakis (3- (3,5-di-butyl). -4-hydroxyphenol) propionate) was added to and dissolved in the resulting solution.

[0095] Next, using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.), the solvent cyclohexane and other volatile components were removed from the solution at a temperature of 270 ° C and a pressure of 1kPa or less. The hydrogen additive was extruded in the form of a strand from the extruder in a molten state, cooled and pelletized to recover the pellets. This hydrogenated ring-opened polymer had a weight average molecular weight (Mw) of 35,000, a hydrogenation rate of 99.9%, and a glass transition temperature (Tg) of 100 ° C. <Example 1>

Mix 99 parts by weight of the DCPZETD ring-opening polymer hydrogenated product obtained in Production Example 1 with 1 part by weight of fine particles (GE Toshiba Silicone Co., Ltd., Tospearl 120) that have the cross-linking power of the polysiloxane polymer. Extruded into a strand using a shaft extruder (Toshiba Machine Co., Ltd., TEM-35B) and cut with a pelletizer to produce pellets for a light diffusion plate.

[0097] Using this light diffusion plate pellet, a light diffusion plate was molded by an injection molding machine (screw diameter φ 90 mm, maximum mold clamping 850 t). The mold has a substantially rectangular cavity surface on the main surface of the fixed mold plate. The dimensions of the cavity surface were 430 mm long, 740 mm wide, and 856 mm diagonal. The cavity depth was 2.0 mm.

[0098] As shown in Figs. 1 and 2, the cavity surface of the fixed mold is provided with twelve hot runner type valve gates having a diameter of 2mm in communication with the cavity surface. The gate gap L2 in the horizontal direction was 185mm, and the gate gap L1 in the vertical direction was 143.3mm. The spacing error in each direction was 0%. In addition, the distance LA1 between the outermost gate 20A and the vertical side 11A of the cavity surface shown in FIG. 1 is 71.7 mm, and the distance LB1 between the outermost gate 20A and the lateral side 12A of the cavity surface is LB1. It was 92.5 mm. The distance 1 ^ \ 2 was 71.7 mm and the distance LB2 was 92.5 mm. The distance L A3 was 71.7 mm, and the distance LB3 was 92.5 mm. The distance LA4 was 71.7 mm and the distance LB4 was 9 2.5 mm. Therefore, the distance error was 0%. Each distance LA1 to LA4 was 50% of the distance L1, and each distance LB1 to LB4 was 50% of the distance L2. The injection molding conditions were a cylinder temperature of 275 ° C, a hot runner temperature of 275 ° C, a mold temperature of 78 ° C, an injection speed of lOOmmZ seconds, and a cooling time of 30 seconds.

[0099] After clamping the mold, the valve gates of the first lateral gate row were opened, and the resin was injected from the valve gates of the first lateral gate row. Subsequently, 1.5 seconds after resin injection from the valve gate of the first horizontal gate row, the second gate gate open the valve gate, and the first and second horizontal gate row gate gates and The resin was injected from the valve gate. Next, when the resin injection amount reached the predetermined amount and it was determined that the resin filling state near the cavity surface was sufficient without sink marks, all valve gates were closed and injection stopped. . At this time, the pressure inside the mold at the time of injection was 180 kgfZcm ² (18 MPa). Then gold on the above conditions After cooling the mold, the light diffusing plate was taken out of the mold to obtain a light diffusing plate.

[0100] The obtained light diffusing plate was a non-defective product having no appearance defect caused by air accumulation. The variation in thickness was measured by a micrometer (manufactured by Mitutoyo Corporation) and found to be 60 m.

[0101] <Example 2>

The dimensions of the cavity surface were changed as follows, and 2.5 seconds after opening the valve gate of the first horizontal gate row, the same as in Example 1 except that the valve gate of the second gate row was opened. A light diffusing plate was obtained. The dimensions of the cavity surface were 600 mm long, 1,020 mm wide, and a diagonal length of 1,183 mm. As shown in Fig. 2, the horizontal gate interval L2 was 233 mm, and the vertical gate interval L 1 was 181.7 mm. The spacing error in each direction was 0%. The distance LA1 between the outermost gate 20A and the longitudinal side 11A of the cavity surface is 1 18.3 mm, and the distance LB 1 between the outermost gate 20A and the lateral side 12A of the cavity surface is 160.5 mm. . The distance LA2 was 118.3 mm and the distance LB2 was 160.5 mm. The distance LA3 was 118.3 mm, and the distance LB3 was 160.5 mm. The distance LA4 was 118.3mm and the distance LB4 was 160.5mm. Therefore, the distance error was 0%. Each distance LA1 to LA4 was 65.1% of the distance L1, and each distance LB1 to LB4 was 68.9% of the distance L2. The depth of the cavity was 2.0 mm. The mold internal pressure at the time of injection was 190kgfZcm ² (19MPa). The obtained light diffusing plate was a good product with no appearance defect caused by air accumulation. Furthermore, the thickness variation of the light diffusing plate was 100 m.

[0102] <Comparative Example 1>

A light diffusion plate was obtained in the same manner as in Example 1 except that all the valve gates were opened at the same time and the resin was injected at the same time. The obtained light diffusing plate had a poor appearance due to burning caused by air accumulation. Furthermore, the variation in the thickness of the light diffusing plate was 200 m.

[0103] <Comparative Example 2>

As shown in Fig. 15, except that the number of valve gates is 8 (2 in the vertical direction and 4 in the horizontal direction) and all the valve gates are opened at the same time and the grease is injected at the same time. Example 1 and Similarly, a light diffusion plate was obtained. The dimensions of the mold cavity surface were 430 mm long, 740 mm wide, and 856 mm diagonal. The depth of the cavity was 2.0mm. Explaining with reference to the symbols in Fig. 2, the lateral gate spacing (L2 in Fig. 2) was 185mm, and the vertical gate spacing (L1 in Fig. 2) was 215mm. The gap error in the horizontal direction was 0%

. The distances (LB1 to LB4 in Fig. 2) were 160.5 mm each, and the distances (LA1 to LA4 in Fig. 2) were each 118.3 mm. The distance error in each direction was 0%. Each distance (LA1 to LA4 in Fig. 2) is 50% of the distance (L1 in Fig. 2), and each distance (LB1 to LB4 in Fig. 2) is equal to the distance (L2 in Fig. 2). It was 50% long. The pressure inside the mold at the time of injection was 200kgfZcm ² (20MPa). Further, the obtained light diffusing plate had a poor appearance due to burning caused by air pockets. Furthermore, the thickness variation of the light diffusing plate was 200 μm.

[0104] <Comparative Example 3>

As shown in Fig. 16, except that the number of valve gates is 16 (4 in the vertical direction and 4 in the horizontal direction), the interval between the horizontal gate rows is narrowed, and the dimensions of the cavity surface are changed as follows. A light diffusing plate was obtained in the same manner as in Comparative Example 1. The dimensions of the mold cavity surface were 600 mm long, 1,02 Omm wide, and 1,183 mm diagonal. Explaining with reference to Fig. 2, the lateral gate spacing (L2 in Fig. 2) was 255mm and the vertical gate spacing (L1 in Fig. 2) was 50mm. The spacing error in each direction was 0%. The distances (LB1 to LB4 in Fig. 2) were 125.5 mm each, and the distances (LA1 to LA4 in Fig. 2) were 112.5 mm each. The distance error in each direction was 0%. Each distance (LA1 to LA4 in FIG. 2) was 225% of the distance (L1 in FIG. 2). Each distance (LB1 to LB4 in FIG. 2) was 50% of the distance (L2 in FIG. 2).

[0105] The depth of the cavity was 2.0 mm. The lateral gate spacing was 230 mm, and the longitudinal gate spacing was 50 mm. In each direction, the spacing error was 0%. The in-mold pressure at the time of injection was 250 kgfZcm ² (25 MPa). Moreover, it was a good product without any appearance defects that could occur due to air accumulation. In addition, the thickness variation of the light diffusing plate was 200 m. In Examples 1 and 2, the in-mold pressure could be kept low, and the obtained light diffusion plate had no appearance defects due to gas burning or the like, and suppressed thickness unevenness. On the other hand, in Comparative Examples 1 and 2, the obtained light diffusion plate had poor appearance and uneven thickness due to gas burn. In Comparative Example 3, the mold pressure could not be kept low, and the obtained light diffusion plate had uneven thickness.

[0108] Using the light diffusion plate pellets, a light diffusion plate was formed by an injection molding machine (screw diameter φ 90 mm, maximum clamping force 85 Ot). The mold has a substantially rectangular cavity surface on the main surface of the fixed mold plate. The dimensions of the cavity surface were 430 mm long, 740 mm wide, and a diagonal length of 856 mm. The cavity depth was 2.0 mm.

As shown in FIGS. 5 and 6, the cavity surface of the fixed mold plate is provided with 16 hot runner type valve gates having a diameter of 2 mm, which communicate with the cavity surface. The gate gap L2 in the horizontal direction was 185mm, and the gate gap L1 in the vertical direction was 107.5mm. The spacing error in each direction was 0%. Also, the distance LA1 between the outermost gate 20A and the longitudinal side 11A of the cavity surface shown in FIG. 5 is 92.5 mm, and the distance LB1 between the outermost gate 20A and the lateral side 12A of the cavity surface is 53. It was 8 mm. The distance LA2 was 92.5 mm and the distance LB2 was 53.8 mm. The distance LA3 was 92.5 mm and the distance LB3 was 53.8 mm. The distance LA4 was 92.5 mm, and the distance LB4 was 53.8 mm. Therefore, the distance error was 0%. Each distance LA1 to LA4 was 50% of the distance L1, and each distance LB1 to LB4 was 50% the distance L2. The injection molding conditions were a cylinder temperature of 275 ° C, a hot runner temperature of 275 ° C, a mold temperature of 78 ° C, an injection speed of lOOmmZ seconds, and a cooling time of 30 seconds.

[0110] After clamping the mold, the first group of valve gates was opened, and the resin was injected from the first group of valve gates. Next, grease spray from the valve gate of the first group 1.5 seconds after exit, the second group of valve gates was opened, and the resin was injected from the first group of valve gates and the second group of valve gates. Subsequently, 1.5 seconds after the injection of the resin from the valve gate of the second group, the valve gate of the third group was opened and the resin was injected from the first to third valve gates. Next, when the injection amount of the resin reaches the planned amount and it is determined that the resin filling state near the cavity surface is sufficient without sink marks, all valve gates are closed and the injection is stopped. did. At this time, the in-mold pressure at the time of injection was 180 kgfZcm ² (18 MPa). Then, after cooling a metal mold | die on the said conditions, the light-diffusion board was picked out from the metal mold | die, and the light-diffusion board was obtained.

[0111] The obtained light diffusing plate was a non-defective product having no appearance defect caused by air accumulation. The variation in thickness was measured by a micrometer (manufactured by Mitutoyo Corporation) and found to be 60 m.

[0112] Example 4>

The dimensions of the cavity surface were changed as follows, and the opening and closing of the valve gate was controlled in the same manner as in Example 1 to obtain a light diffusing plate. The dimensions of the cavity surface were 600 mm long, 1,02 Omm wide, and 1,183 mm diagonal. As shown in FIG. 6, the horizontal gate interval L2 was 255 mm, and the vertical gate interval L1 was 150 mm. The spacing error in each direction was 0%. The distance L A1 between the outermost gate 20A and the longitudinal side 11A of the cavity surface is 75 mm, and the distance LB 1 between the outermost gate 20A and the lateral side 12A of the cavity surface is 127.5 mm. . The distance LA2 was 75 mm and the distance LB2 was 127.5 mm. The distance LA3 was 75 mm and the distance LB3 was 127.5 mm. The distance LA4 was 75mm and the distance LB4 was 127.5mm. Therefore, the distance error was 0%. Each distance LA1 to LA4 was 50% of the distance L1, and each distance LB1 to LB4 was 50% of the distance L2. The depth of the cavity was 2.0mm. The mold internal pressure at the time of injection was 180kgfZcm ² (18MPa). The obtained light diffusing plate was a good product with no appearance defect caused by air accumulation. Furthermore, the thickness variation of the light diffuser was 80 μm.

[0113] <Comparative Example 4>

Example except that all valve gates are opened at the same time and the grease is injected at the same time. A light diffusing plate was obtained in the same manner as in 3. The obtained light diffusing plate had a poor appearance due to burning caused by air accumulation. Furthermore, the variation in the thickness of the light diffusing plate was 200 m.

[0114] <Comparative Example 5>

As shown in Fig. 17, the number of valve gates is 8 (2 in the vertical direction and 4 in the horizontal direction), and the vertical gate interval is narrower than the horizontal gate interval, and all the valve gates are used simultaneously. A light diffusing plate was obtained in the same manner as in Example 2 except that the resin was simultaneously injected and the pressure inside the mold was 25 MPa. The obtained light diffusing plate had a poor appearance due to burning caused by air pockets. Furthermore, the variation in the thickness of the light diffusing plate is about 200 m.

[0115] In Examples 3 and 4, the in-mold pressure could be kept low, and the obtained light diffusing plate had no appearance defects due to gas burning or the like, and suppressed thickness unevenness. On the other hand, in Comparative Example 4, the obtained light diffusion plate had poor appearance and uneven thickness due to gas burning or the like. In Comparative Example 5, the in-mold pressure could not be kept low, and the obtained light diffusion plate had uneven thickness.

Industrial applicability

[0116] The method for producing a flat molded product of the present invention is suitable for producing a flat molded product using a mold, such as a light diffusing plate, a light guide plate, a reflecting plate, etc. constituting a backlight device of a liquid crystal display. It can be applied to the production of optical components and other flat plate molded products.

Claims

The scope of the claims

[1] A method for producing a resin-made flat plate molded product using a mold for injection molding, wherein the mold has a substantially rectangular cavity surface corresponding to the shape of the flat plate molded product. And a fixed mold plate provided with a plurality of gates communicating with the cavity surface, wherein the plurality of gates have a longitudinal pitch along a substantially rectangular longitudinal direction and lateral direction of the cavity surface. Considering a lattice with L1 and a horizontal pitch of L2, it is placed at the position of the intersection of this lattice,

In the four outermost gates, which are the gates closest to each vertex of the substantially rectangular cavity surface, the distances LA1 to LA4 between each outermost gate and the nearest side of the lateral sides of the cavity surface are The distance between each outermost gate and the nearest side in the vertical direction of the above-mentioned cavity surface is 120% to 10% of the pitch L1, and LB1 to LB4 is 120% to 10% of the pitch L2. Yes,

The plurality of gates as a plurality of vertical gate rows composed of a plurality of gates arranged along the vertical direction and a plurality of horizontal gate rows composed of a plurality of gates arranged along the horizontal direction,

Of the number of the vertical gate rows and the number of the horizontal gate rows, the number of gate rows in at least one direction is an odd number,

In the odd-numbered gate row in any direction, a plurality of gate rows are closest to an intersection of diagonal lines of the cavity surface, and a row including a central gate that is a gate of a position is a first gate row, this first row. 2nd gate row including 2 gate rows close to 1 gate row, 3rd gate row including each gate row close to each gate row constituting this 2nd gate row, ... A first step of injecting the resin from the first gate row, and an nth gate row (n is an integer of 2 or more) including each gate row close to each gate row

When the injection amount of the (n-1) th gate row force reaches a predetermined amount, the nth gate row force is also the nth step of injecting the resin (if n is a value of n, then n is (Established for all values from 2 to k)

The manufacturing method of the flat plate molded article characterized by comprising.

[2] The distances LA1 to LA4 in the outermost gates are substantially the same as each other, 2. The method for manufacturing a flat molded article according to claim 1, wherein the distances LB1 to LB4 in each outermost gate are substantially the same.

[3] The method for producing a flat molded article according to claim 1 or 2, wherein the odd-numbered directional force of the gate row is a longer one of a longitudinal direction and a transverse direction.

[4] A method for producing a substantially rectangular flat plate molded article by injection molding a resin using a mold for injection molding,

The mold includes a movable mold plate, and a fixed mold plate having a substantially rectangular cavity surface corresponding to the shape of the flat plate molded product and provided with a plurality of gates communicating with the cavity surface. Prepared,

The plurality of gates have a pitch in the first direction along the first side of the substantially rectangular shape of the cavity surface as L1, and a pitch in the second direction along the second side orthogonal to the first direction. Is placed at the position of the intersection of this lattice when considering the lattice of L2,

The plurality of gates are a plurality of first gate rows made of a plurality of gates arranged along the first direction and a plurality of second gate rows made of a plurality of gates arranged along the second direction,

In the first gate row, the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the eleventh gate row and the twelfth gate row, and the two gates close to the eleventh gate row and the twelfth gate row. The rows are the 13th gate row and the 14th gate row, respectively. In the second gate row, the two gate rows closest to the intersection of the diagonal lines of the cavity surface are the 21st gate row and the 22nd gate row, the 21st gate row. When the two gate rows close to the row and the 22nd gate row are the 23rd gate row and the 24th gate row, respectively, and each gate is expressed as (first gate row, second gate row),

First group including (13, 21), (11, 22), (12, 21), (14, 22), (13, 22), (11, 21), (12, 22) A first step of injecting the resin from each gate included in any one of the second groups including each gate of (14, 21),

When the injection amount in the first step reaches a predetermined amount, the second step of injecting the resin from the gate group included in the other group;

When the injection amount in the second step reaches a predetermined amount, the 23rd gate row and the 24th gate row A third step of injecting the resin from each of the gates;

The manufacturing method of the flat plate molded article characterized by including.

A method for producing a substantially rectangular flat plate molded product by injection molding a resin using a mold for injection molding,

One of the first group including the gates of (11, 22) and (12, 21) and the second group including the gates of (11, 21) and (12, 22) A first step of injecting the resin from each included gate;

A second step of injecting the resin from each of the gates included in the other group when the injection amount in the first step reaches a predetermined amount;

A third step of injecting the resin from each gate of the thirteenth gate row, the fourteenth gate row, the twenty-third gate row, and the twenty-fourth gate row when the injection amount in the second step reaches a predetermined amount; The manufacturing method of the flat molded article characterized by including these. [6] In the four outermost gates that are the gates closest to the vertices of the substantially rectangular shaped cavity surface, the nearest sides of the outermost gate and the side in the second direction of the cavity surface. The distance LA1 to LA4 is 120% to 10% of the pitch L1, and the distance LB1 to LB4 between each outermost gate and the nearest side of the first side of the cavity surface is LB1 to LB4, 6. The method for producing a flat plate molded product according to claim 4, wherein the pitch L2 is 120% to 10% of the pitch L2.

7. The distances LA1 to LA4 at the outermost gates are substantially the same as each other, and the distances LB1 to LB4 at the outermost gates are substantially the same as each other. Manufacturing method for flat plate products.

[8] When the number of gates is N (pieces), the depth of the cavity formed in the fixed mold is t (mm), and the area of the cavity surface is S (mm ² ), The method for producing a flat plate molded article according to any one of claims 1 to 7, wherein 1) is satisfied.

(S / (t + 6)) X 10-4 ≤ N ≤ (237 10—4 '' '

[9] A flat plate molded product produced by the method for producing a flat molded product according to any one of claims 1 to 8.