JP2012061836A - Method of manufacturing surface shape transfer resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface shape transfer resin sheet manufacturing method that can accurately transfer a transfer pattern to the surface of a resin sheet and, in addition, can prevent the occurrence of a winding phenomenon at a shaped roll.SOLUTION: A resin sheet 53 is formed by continuously extruding a resin in a heat-melting state from a die 58, and the resin sheet 53 is inserted between an upper roll 63 and an intermediate roll 64. Next, the resin sheet 53 is conveyed while being firmly attached to the intermediate roll 64, and the conveyed resin sheet 53 is inserted between the intermediate roll 64 and a lower roll 65. Upon insertion between the intermediate roll 64 and the lower roll 65, an intaglio transfer pattern 69 formed on the lower roll 65 is transferred to the surface 76 of the resin sheet 53. As the lower roll 65, a shaped roll is used, which is equipped with the intaglio transfer pattern 69 having the surface with a wetting tension of ≤35 mN/m measured conforming to JIS K6768.

Description

  The present invention relates to a method for producing a surface shape transfer resin sheet that can be used for applications such as light diffusion plates and optical films.

The surface shape transfer resin sheet is a sheet obtained by continuously extruding a melt-kneaded resin from a die to form a resin sheet, and transferring the uneven shape of the transfer mold to the resin sheet.
As a method for producing a surface shape transfer resin sheet, for example, a step of sandwiching a continuous resin sheet continuously extruded from a die between a first pressing roll and a second pressing roll, and adhesion to the surface of the second pressing roll There has been proposed a manufacturing method including a step of conveying the material while it is left and a step of sandwiching between a second pressing roll and a third pressing roll (see, for example, Patent Document 1). In this method, a transfer mold is attached to the third roll, and when the resin sheet is sandwiched between the second pressing roll and the third pressing roll, the uneven shape is transferred to the surface of the resin sheet.

JP 2009-220555 A

  As a use of the surface shape transfer resin sheet, a use as a light diffusion plate or an optical film incorporated in a backlight device of a liquid crystal display device is becoming widespread. In this case, if the uneven shape is not accurately transferred when the resin sheet is manufactured (if the transfer rate is not high), it is difficult to impart optical characteristics as designed to the light diffusion plate and the optical film. Therefore, in recent years, establishment of a technique for accurately transferring a transfer mold onto a resin sheet is desired.

As such a method, for example, a method of increasing the temperature of the roll on which the transfer mold is mounted can be considered. In this method, the fluidity of the resin sheet can be increased by the heat transmitted from the roll to the resin sheet, and the resin can be introduced into the tip of the groove portion of the transfer mold, so that an improvement in transfer rate can be expected.
However, if the roll temperature is too high, a “trailing phenomenon” in which the resin sheet sticks to the roll surface tends to occur. As a result, there is a problem that a “tack mark” is formed on the surface of the resin sheet after the shape transfer.

  An object of the present invention is to provide a method for producing a surface shape transfer resin sheet that can accurately transfer a transfer mold to the surface of a resin sheet and can prevent the occurrence of a trail phenomenon in a shape roll. .

  The method for producing a surface shape transfer resin sheet of the present invention for achieving the above object comprises a step of forming a continuous resin sheet by continuously extruding a resin from a die in a heated and melted state, and measuring in accordance with JIS K 6768 The shape of the transfer mold is transferred by pressing the surface of the transfer mold against the surface of the continuous resin sheet using a shape roll having a transfer mold having a surface with a wetting tension of 35 mN / m or less. And a process.

Moreover, in the manufacturing method of the surface shape transfer resin sheet of this invention, it is suitable to use the shape roll which has the transfer type | mold in which the organic polysiloxane process is performed with respect to the said surface as said shape roll.
Moreover, in the manufacturing method of the surface shape transfer resin sheet of this invention, it is suitable to use the shape roll which has the transfer type by which the said surface was wash | cleaned after the said organic polysiloxane process as said shape roll.

  Furthermore, in the method for producing a surface shape transfer resin sheet of the present invention, when the glass transition temperature of the resin is expressed as Tg (° C.) and the thickness of the continuous resin sheet after transfer is expressed as T (mm), the shape The surface temperature of the roll is Tg-30 (° C.) to Tg + 50 (° C.), the transport speed of the continuous resin sheet is 0.2 / T (m / min) to 50 / T (m / min), It is preferable that the surface temperature of the continuous resin sheet before contacting the shape roll is Tg + 50 (° C.) to Tg + 160 (° C.).

  According to the method for producing a surface shape transfer resin sheet of the present invention, since the wetting tension of the surface of the transfer mold (the contact surface with the continuous resin sheet) is 35 mN / m or less, even if the temperature of the shape roll increases, Occurrence of the “torre phenomenon” in which the resin sheet sticks to the transfer mold can be prevented. Therefore, by appropriately controlling the temperature of the shape roll together with the production conditions such as the transport speed of the resin sheet and the surface temperature of the resin sheet, the resin can be satisfactorily introduced into the concave portion of the transfer mold. Therefore, the transfer mold can be accurately transferred onto the surface of the resin sheet. As a result, if the resin sheet obtained by this manufacturing method is used as a light diffusing plate or an optical film of a liquid crystal display device, excellent optical characteristics can be expressed.

FIG. 1 is a schematic side view of a liquid crystal display device on which a resin sheet according to an embodiment of the present invention is mounted. FIG. 2 is a schematic perspective view of the liquid crystal display device shown in FIG. FIG. 3A is a schematic perspective view of a light diffusing plate made of a resin sheet according to an embodiment of the present invention. FIG. 3B is a schematic perspective view of an optical film made of a resin sheet according to an embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a main part of the lamp box showing a mounting state of the light diffusion plate and the optical film. FIG. 5 is a schematic configuration diagram of a manufacturing apparatus used in the method for manufacturing a resin sheet according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of the intaglio transfer mold attached to the lower roll. FIG. 7 is a view showing a first modified example (substantially semicircular shape) of the intaglio transfer mold. FIG. 8 is a diagram showing a second modified example (substantially prism shape) of the intaglio transfer type. FIG. 9 is a view showing a modification of the sheet manufacturing apparatus shown in FIG. FIG. 10 is a diagram showing IR spectra of the transfer mold surfaces of Examples and Comparative Examples.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<Overall configuration of liquid crystal display device>
FIG. 1 is a schematic side view of a liquid crystal display device on which a resin sheet according to an embodiment of the present invention is mounted. FIG. 2 is a schematic perspective view of the liquid crystal display device shown in FIG.
The liquid crystal display device 1 (liquid crystal television) is a so-called direct liquid crystal display device, and includes a backlight system 2, a liquid crystal panel 3 disposed in front of the backlight system 2, a backlight system 2, and a liquid crystal panel 3. And an optical film 4 disposed between the two. In FIG. 1 and FIG. 2, the liquid crystal display device 1 is shown in a posture with its front side facing the upper side of the drawing for the sake of convenience. Further, the scales of the constituent members such as the liquid crystal display device 1, the backlight system 2, and the liquid crystal panel 3 shown in the following drawings are set for convenience of explanation, and the scales of all the constituent members are the same. Not that.

The backlight system 2 has a rectangular plate-shaped rear wall 5 and a rectangular frame-shaped side wall 6 integrally standing upright from the periphery of the rear wall 5, and is made of a thin box-shaped resin whose front side is open. A lamp box 7, a plurality of linear light sources 8 provided in the lamp box 7, and a light diffusion plate 10 that closes an open surface 9 (front surface) of the lamp box 7 are provided.
That is, the box-shaped lamp box 7 has an open surface 9 whose outline is defined by a square-shaped side wall 6, and a linear light source 8 is provided in a space surrounded by the side wall 6 and the rear wall 5. On the inner surface of the rear wall 5 of the lamp box 7, for example, a reflection plate (not shown) for reflecting light incident on the rear wall 5 side from the linear light source 8 toward the open surface 9 side of the box is attached to the whole. It has been.

The linear light source 8 is, for example, a cylindrical lamp having a diameter of 2 mm to 4 mm. The plurality of linear light sources 8 are arranged in parallel with each other at an equal interval in a state where they are spaced apart from the back surface 18 of the light diffusion plate 10.
The distance L between the centers of the adjacent linear light sources 8 is preferably 30 mm to 60 mm from the viewpoint of power saving. Moreover, it is preferable that the distance D of the back surface 18 (for example, center part in the back surface 18) of the light diffusing plate 10 and the center of the linear light source 8 is 10 mm-20 mm from a viewpoint of thickness reduction. Moreover, it is preferable that the ratio (L / D) of the space | interval L with respect to the distance D is 2.5-4.0. In particular, the distance L is preferably 40 mm to 55 mm, and the distance D is preferably 13 mm to 17 mm. The number of the linear light sources 8 is inevitably determined by the size of the lamp box 7 (screen size of the liquid crystal display device 1) and the interval L. For example, in the 32 type liquid crystal display device 1, the number is 6-10. Preferably there is. In FIGS. 1 and 2, only five linear light sources 8 are shown for easy illustration.

Moreover, as the linear light source 8, well-known cylindrical lamps, such as a fluorescent tube (cold cathode tube), a halogen lamp, a tungsten lamp, can be used, for example. Further, as the light source of the backlight system 2, a point light source such as a light emitting diode (LED) can be used instead of the linear light source 8.
The liquid crystal panel 3 includes a liquid crystal cell 11 and a pair of polarizing plates 12 and 13 that sandwich the liquid crystal cell 11 from both sides in the thickness direction. Such a liquid crystal panel 3 is disposed on the front surface of the backlight system 2 so that the polarizing plate 12 on the back side and the light diffusion plate 10 face each other.

As the liquid crystal cell 11, for example, a known liquid crystal cell such as a TFT liquid crystal cell or an STN liquid crystal cell can be used.
The optical film 4 is not particularly limited, and examples thereof include a microlens film, a substantially semicircular lenticular lens film, a diffusion film, a prism film, and a reflective polarization separation film.
<Configuration of light diffusion plate and optical film>
FIG. 3A is a schematic perspective view of a light diffusing plate made of a resin sheet according to an embodiment of the present invention. FIG. 3B is a schematic perspective view of an optical film made of a resin sheet according to an embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a main part of the lamp box showing a mounted state of the light diffusion plate.

As shown in FIG. 3A, the light diffusion plate 10 is formed in a square plate shape that is substantially the same as the frame shape of the side wall 6 of the lamp box 7.
On one main surface (front surface 16) of the light diffusing plate 10, a plurality of semi-elliptical ridges 17 extending between a pair of opposed peripheral edges of the light diffusing plate 10 are formed in a streak shape. That is, on the front surface 16 of the light diffusing plate 10, semi-elliptical ridges 17 and concave grooves 19 between adjacent semi-elliptical ridges 17 are alternately formed.

The semi-elliptical ridge 17 has a substantially semi-elliptical outline in a cut surface perpendicular to the shape thereof. A large number of semi-elliptical ridges 17 are arranged at an equal interval E ₁ (for example, ₁ μm to 15 μm) in parallel with each other. The distance (pitch P ₁ ′) between the centers of adjacent semi-elliptical ridges 17 is, for example, 200 μm to 500 μm. The height of the semi-elliptical ridge 17 (depth of the groove 19) _{H 1} 'is, for example, 100Myuemu～500myuemu. The aspect ratio represented by the ratio of the 'height _{H 1} for "pitch _{P 1} of the semi-elliptic convex strip _{17 (H 1' / P 1} ') , for example, 0.4 or more, preferably, 0.5 ~ 0.7.

On the other hand, the other main surface (back surface 18) of the light diffusing plate 10 is a flat surface having no irregularities.
Moreover, as shown in FIG. 4, thickness T1 of the light diffusing plate 10 from the back surface 18 to the top part of the semi-elliptical protrusion 17 in the front surface 16 is ₁ mm-4 mm, for example.
Further, as shown in FIG. 3B, the optical film 4 is formed in a square plate shape that is substantially the same as the shape of the light diffusion plate 10.

  On one main surface (front surface 20) of the optical film 4, a plurality of convex shapes 21 extending between a pair of opposing peripheral edges of the optical film 4 are formed in a streak shape. The convex shape 21 is, for example, a semi-elliptical shape, a prism shape or the like (a semi-elliptical shape in FIG. 3B). That is, on the front surface 20 of the optical film 4, convex shapes 21 and concave grooves 22 between adjacent convex shapes 21 are alternately formed.

A large number of the convex shapes 21 are arranged at an equal interval E ₂ (for example, 1 μm to 15 μm) in parallel with each other. The distance (pitch P ₂ ′) between the centers of adjacent convex shapes 21 is, for example, 30 μm to 500 μm. The height of the convex shape 21 (the depth of the groove 22) _{H 2} 'is, for example, 10 m to 500 m. The aspect ratio represented by the ratio of 'the height _{H 2} to' pitch _{P 2} of the convex _{21 (H 2 '/ P 2} ') , for example, 0.3 or more, preferably, 0.4 to 0 .7.

On the other hand, the other main surface (back surface 23) of the optical film 4 is a flat surface having no irregularities.
Further, as shown in FIG. 4, the thickness _{T 2} of the optical film 4 from the back 23 to the top of the convex shape 21 on the front 20 is, for example, 0.1 mm to 1 mm.
The raw materials for the light diffusion plate 10 and the optical film 4 are not particularly limited, and for example, an amorphous translucent resin or a crystalline resin can be used.

  As an amorphous translucent resin to be used, for example, acrylic resin, styrene resin, polycarbonate, cyclic polyolefin, cyclic olefin copolymer, MS resin (methyl methacrylate-styrene copolymer resin), ABS resin ( And acrylonitrile-butadiene-styrene copolymer resin) and AS resin (acrylonitrile-styrene copolymer resin).

Examples of the crystalline resin used include propylene-based resins and ethylene-based resins.
The above amorphous translucent resin and crystalline resin can be used alone or in combination of two or more. Of these, when used as a raw material for the light diffusing plate 10, a styrene resin and a polycarbonate are preferable, and a styrene resin is preferably used alone. Moreover, when using as a raw material of the optical film 4, Preferably, a polycarbonate, an acrylic resin, MS resin, and AS resin are mentioned.

Moreover, the light diffusing plate 10 and the optical film 4 can contain a light diffusing agent (light diffusing particles) if necessary.
The light diffusing agent is not particularly limited as long as it has a refractive index different from that of the translucent resin constituting the light diffusing plate 10 and the optical film 4 and can diffuse transmitted light. For example, as an inorganic light diffusing agent, , Calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide, zinc oxide and the like. These may be subjected to a surface treatment with a fatty acid or the like.

Examples of the organic light diffusing agent include styrene polymer particles, acrylic polymer particles, and siloxane polymer particles. Preferably, the weight average molecular weight is 500,000 to 5,000,000. Examples include coalescent particles and crosslinked polymer particles having a gel fraction of 10% by mass or more when dissolved in acetone.
The light diffusing agents can be used alone or in combination of two or more.

  When the light diffusing plate 10 and the optical film 4 contain a light diffusing agent, the blending ratio of the light diffusing agent is 0.001 to 1 part by weight, preferably 0.001 with respect to 100 parts by weight of the translucent resin. -0.01 parts by weight. Moreover, a light-diffusion agent can be used as a masterbatch with the said translucent resin. Further, the absolute value of the difference between the refractive index of the translucent resin and the refractive index of the light diffusing agent is usually 0.01 to 0.20, preferably 0.02 to 0.02 from the viewpoint of light diffusibility. 0.15.

Further, if necessary, the light diffusion plate 10 and the optical film 4, for example, an antistatic agent, an ultraviolet absorber, a heat stabilizer, an antioxidant, a weathering agent, a light stabilizer, a fluorescent whitening agent, a processing stabilizer, and the like. These various additives can also be added.
The ultraviolet absorber is not particularly limited, and examples thereof include salicylic acid phenyl ester ultraviolet absorbers, benzophenone ultraviolet absorbers, triazine ultraviolet absorbers, and benzotriazole ultraviolet absorbers. When adding an ultraviolet absorber, it is preferable to add 0.1-3 weight part of ultraviolet absorbers with respect to 100 weight part of translucent resin. If it is the above-mentioned range, the bleeding to the surface of an ultraviolet absorber can be suppressed and the external appearance of the light-diffusion plate 10 and the optical film 4 can be maintained favorable.

  The heat stabilizer is not particularly limited, and examples thereof include manganese compounds and copper compounds. When adding the heat stabilizer, it is preferably added together with the ultraviolet absorber, and the heat stabilizer is preferably added at a ratio of 2 parts by weight or less with respect to 1 part by weight of the ultraviolet absorber in the translucent resin. More preferably, 0.01 to 1 part by weight of a heat stabilizer is added to 1 part by weight of the ultraviolet absorber in the translucent resin.

Moreover, it does not restrict | limit especially as antioxidant, For example, a hindered phenol compound, a hindered amine compound, etc. are mentioned. When adding antioxidant, it is preferable to add 0.1-3 weight part of antioxidant with respect to 100 weight part of translucent resin.
As shown in FIG. 4, the light diffusion plate 10 diffuses light with respect to the side wall 6 of the lamp box 7 at a position where the semi-elliptical ridges 17 are parallel to the linear light source 8 in the lamp box 7. The back surface 18 of the plate 10 is brought into contact with the lamp box 7 and fixed thereto. As a result, the open surface 9 of the lamp box 7 is blocked by the light diffusion plate 10. The optical film 4 is disposed in front of the light diffusing plate 10.
<Method for producing light diffusion plate (resin sheet)>
The light diffusion plate 10 and the optical film 4 described above can be produced by cutting a resin sheet produced by the following method. In addition, below, although the case where the light diffusing plate 10 is manufactured is demonstrated, the optical film 4 can also be manufactured according to the following method.

FIG. 5 is a schematic configuration diagram of a manufacturing apparatus used in the method for manufacturing a resin sheet according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of the intaglio transfer mold attached to the lower roll.
The sheet manufacturing apparatus 51 takes out the resin sheet 53, a sheet molding machine 52 that extrudes the raw material resin into a sheet shape, a set of pressing rolls 54 for molding the extruded resin sheet 53 by pressing. And a pair of take-up roll groups 55.

The sheet forming machine 52 is configured by a known extruder such as a single screw extruder or a twin screw extruder. The sheet molding machine 52 includes a cylinder 56 for heating and melting (softening) the resin material, a hopper 57 for feeding the resin material into the cylinder 56, and a die 58 for extruding the softened resin material in the cylinder 56. Including.
As the die 58, a metal T die used for a normal extrusion molding method or the like is used. The width of the lip (die lip 59) of the die 58 is selected according to the width of the target resin sheet 53, and is, for example, 200 mm to 3000 mm.

The press roll group 54 includes three press rolls 63 to 65 as a mechanism for forming irregularities on the front and back surfaces 75 and 76 of the resin sheet 53 by a transfer mold while molding the resin sheet 53 by pressing.
The surface 76 of the resin sheet 53 is a surface that forms the front surface 16 of the light diffusing plate 10, and is a shape transfer surface that is finally subjected to shape processing. On the other hand, the back surface 75 of the resin sheet 53 is a surface that forms the back surface 18 of the light diffusing plate 10, and is a surface that is not finally subjected to shape processing (for example, a flat surface that maintains flatness in this embodiment). It is.

  The three pressing rolls 63 to 65 are each made of a cylindrical metal roll (for example, made of chromium, copper, nickel, stainless steel, or a resin surface material), and the temperature of the peripheral surface (surface It is a cooling roll having a function of adjusting (temperature). The three pressing rolls 63 to 65 are arranged in the vertical direction so that the axes are parallel to each other as the upper roll 63, the intermediate roll 64, and the lower roll 65 as the shape roll in order from top to bottom. .

In this embodiment, the peripheral surface 66 of the upper roll 63 and the peripheral surface 67 of the intermediate roll 64 are, for example, made smooth surfaces (mirror surfaces) by being mirror-finished.
An intaglio transfer die 69 for forming the semi-elliptical ridges 17 and the concave grooves 19 on the resin sheet 53 is provided on the peripheral surface 68 of the lower roll 65. The intaglio transfer mold 69 is, for example, copper-plated on a cylindrical metal roll, the plated metal roll is placed on a lathe, and a diamond bite is used to engrave the copper-plated layer into a target lens shape Or by forming a groove by chemical etching or the like, and then performing a chrome plating process on copper. Note that the surfaces of the upper roll 63 and the intermediate roll 64 not provided with the intaglio transfer mold 69 are also subjected to plating treatment such as chrome plating, copper plating, nickel plating, Ni-P plating, if necessary. It may be.

In order to form a more precise shape with good reproducibility, a lathe-diamond bit combination is preferred, and the chromium plating thickness applied on copper is preferably 5 μm or less, more preferably 2 μm or less.
In the intaglio transfer mold 69, as shown in FIG. 6, a number of semi-elliptical concave grooves 70 opposite to the semi-elliptical ridges 17 are formed in a stripe shape along the circumferential direction of the lower roll 65. That is, the intaglio transfer mold 69 includes a convex strip 71 between the semi-elliptical concave groove 70 and the adjacent semi-elliptical concave groove 70 (this convex stripe 71 is opposite to the concave groove 19, and the intaglio transfer mold 69. And the surface of the ridges 71 are alternately arranged along the axial direction of the lower roll 65.

The depth H ₁ of the semi-elliptical concave groove 70 is slightly larger than the height H ₁ ′ of the semi-elliptical ridge 17 and is, for example, 10 μm to 500 μm, preferably 20 μm to 300 μm or less. If the depth H ₁ is excessively large, it becomes difficult to allow the resin to enter the tip of the semi-elliptical concave groove 70. Moreover, although the distance (pitch P ₁ ) between the centers of the adjacent semi-elliptical grooves 70 is appropriately determined according to the shape of the semi-elliptical ridges 17, for example, 30 μm to 500 μm, preferably 40 μm to 450 μm. . If the pitch P ₁ is less than 30 [mu] m, there is a possibility that the resin solidifies immediately in contact with the lower roll 65, to obtain a result, the resin does not penetrate to the tip of the semi-elliptical groove 70, the imprint profile to target There is a risk that it will not be possible. On the other hand, if the pitch P ₁ is greater than 500 [mu] m, or also observed in muscle pitch gross moire patterns with a liquid crystal panel 3 and the optical film 4 is likely to be or appear.

The aspect ratio represented by the height _{H 1} of the ratio of the pitch _{P 1} of the semi-elliptical groove 70 _{(H 1} / _P 1) is, for example, 0.3 or more, preferably, 0.4 to 0.7 It is.
The difference between the height H ₁ ′ of the semi-elliptical ridge 17 and the depth H ₁ of the semi-elliptical groove 70 is that the intaglio transfer mold 69 is transferred to the resin sheet 53 to form the semi-elliptical ridge 17. This is due to the transfer rate (H ₁ ′ / H ₁ ) (%).

The surface of the intaglio transfer mold 69 having such a shape (contact surface with the resin sheet 53) is subjected to organic polysiloxane treatment.
In this embodiment, the organic polysiloxane treatment refers to a treatment (sealing treatment) in which fine holes (microcracks) generated when chromium plating is applied to the lower roll 65 are filled with organic polysiloxane. A method of applying an organic polysiloxane solution to the surface of the intaglio transfer mold 69 and drying, a method of polymerizing the organic siloxane on the surface of the intaglio transfer mold 69, and a material of the intaglio transfer mold 69 (for example, chromium plating). It can carry out by the method of making it react chemically and combining.

The organic polysiloxane includes, for example, a skeleton of a bifunctional siloxane unit, a trifunctional siloxane unit, and a tetrafunctional siloxane unit.
As a functional group which couple | bonds a siloxane skeleton, a C1-C10 hydrocarbon group, Preferably, a C1-C6 hydrocarbon group is mentioned, for example. Specifically, for example, alkyl such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, octyl group, nonyl group, decyl group, etc. A group, for example, a cycloalkyl group such as a cyclohexyl group, for example, an aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, for example, an aralkyl group such as a benzyl group, a phenylethyl group, a phenylpropyl group, for example, vinyl Group, allyl group, propenyl group, isopropenyl group, butenyl group, pentenyl group, hexenyl group, octenyl group and other alkenyl groups, for example, cycloalkenyl groups such as cyclohexenyl group, and one of hydrogen atoms of these hydrocarbon groups Part or all of the halogen source such as fluorine, bromine and chlorine , Those substituted with a cyano group, specifically, for example, chloromethyl group, chloropropyl group, bromoethyl group, a halogen-substituted alkyl groups such as trifluoropropyl group, for example, such as cyanoethyl group.

Further, after the organic polysiloxane treatment, the surplus organic polysiloxane remaining on the surface of the intaglio transfer mold 69 can be removed by washing the surface of the intaglio transfer mold 69. Thereby, even if the organic polysiloxane treatment remains and fine irregularities are generated on the surface of the intaglio transfer mold 69, the roughened surface can be leveled.
The intaglio transfer mold 69 can be cleaned by, for example, a method of wiping the surface of the intaglio transfer mold 69 after the organic polysiloxane treatment with fibers (for example, cotton, silk, etc.).

By performing the organic polysiloxane treatment as described above, the wetting tension measured in accordance with JIS K 6768 on the surface of the intaglio transfer mold 69 is set to 35 mN / m or less. The surface tension of the intaglio transfer mold 69 is preferably 5 mN / m to 30 mN / m.
Further, motors (not shown) are connected to the rotation shafts of the pressing rolls 63 to 65, respectively, so that the upper roll 63 and the lower roll 65 can rotate counterclockwise, and the intermediate roll 64 rotates clockwise. Is possible. That is, the pressing rolls 63 to 65 are “rotatable counterclockwise”, “rotatable clockwise”, and “rotatable counterclockwise” in order from the top. Thereby, all the rolls 63 to 65 can be rotated synchronously with the resin sheet 53 sandwiched therebetween. Moreover, the conveyance speed of the resin sheet 53 can be adjusted by adjusting the rotational speed of the press rolls 63-65 suitably.

The diameter of each pressing roll 63-65 is 100 mm-500 mm, for example. Moreover, when a metal roll is used as the pressing rolls 63 to 65, the surface thereof may be subjected to plating treatment such as chromium plating, copper plating, nickel plating, Ni-P plating, or the like.
In addition, a heater 72 for heating the surface 76 (the surface on the transfer side) of the resin sheet 53 conveyed on the intermediate roll 64 is installed near the intermediate roll 64.

  The heater 72 is disposed so as to be separated from the peripheral surface 67 of the intermediate roll 64, and heats the resin sheet 53 being conveyed from the surface 76 side. As the heater 72, for example, a known heater such as an infrared heater can be used. The heater 72 may be an in-line type installed in a line where the resin sheet 53 is conveyed, or may be a handy type that can be measured by an operator.

The pair of take-up roll groups 55 includes a pair of take-up rolls 85 and 86 that sandwich the resin sheet 53 from both sides in the thickness direction.
The take-up rolls 85 and 86 are each made of a cylindrical roll (usually a roll made of resin), and are opposed to each other so that the upper end of the lower take-up roll 85 is at the same height as the lower end of the lower roll 65. Has been. Thereby, since the resin sheet 53 delivered from the lower roll 65 can be horizontally conveyed while being supported at the height immediately after the delivery, the conveyance resistance can be reduced.

Next, a method for manufacturing the resin sheet 53 using the above-described manufacturing apparatus will be described.
(1) Extrusion Step First, the raw material resin is charged into the hopper 57 of the sheet forming machine 52, melted and kneaded by the cylinder 56, and then supplied to a feed block (not shown). The temperature of the cylinder 56 is appropriately adjusted so that the intermediate roll 64 inlet temperature T (before R2) of the surface 75 before the resin sheet 53 comes into contact with the intermediate roll 64 is in a range of 200 ° C. to 290 ° C., for example. Specifically, it is set to 190 ° C to 250 ° C.

Next, the resin in the feed block (not shown) is continuously extruded as the resin sheet 53 by being extruded from the die 58.
(2) First Pressing Step and First Conveying Step The resin sheet 53 extruded from the die 58 is first fed into the gap (gap) between the upper roll 63 and the intermediate roll 64 (in this case, melted as necessary) A bank is formed), and is sandwiched and pressed between the upper roll 63 and the intermediate roll 64. Thereafter, the back surface 75 (back surface 18) is brought into close contact with the peripheral surface 67 of the intermediate roll 64 and conveyed. During conveyance, the resin sheet 53 is heated by the heater 72 from the surface 76 side while being cooled by the intermediate roll 64. The surface temperature of the upper roll 63 and the intermediate roll 64 is preferably lower than the extrusion temperature of the resin sheet 53. For example, the surface temperature of the upper roll 63 is 40 ° C to 160 ° C, and the surface temperature of the intermediate roll 64 is 50 ° C to 200 ° C.

On the other hand, the output of the heater 72 is Tg + 50 ° C. when the lower roll 65 inlet temperature T (before R3) of the surface 76 before the resin sheet 53 contacts the lower roll 65 is, for example, the glass transition temperature of the raw material resin is Tg. ≦ T (before R3) ≦ Tg + 160 ° C., preferably Tg + 70 ° C. ≦ T (before R3) ≦ Tg + 140 ° C. Thereby, the resin sheet 53 in a state in which appropriate fluidity is maintained can be plunged between the intermediate roll 64 and the lower roll 65. Therefore, the resin can be satisfactorily introduced to the tip of the semi-elliptical concave groove 70 of the intaglio transfer mold 69.
(3) Second Pressing Step and Second Conveying Step Thereafter, the resin sheet 53 to be conveyed enters (gap) between the intermediate roll 64 and the lower roll 65 and is sandwiched between the intermediate roll 64 and the lower roll 65. Pressed. Then, when the intermediate roll 64 and the lower roll 65 are pressed, the surface shape of the intaglio transfer mold 69 is transferred to the surface 76 (front surface 16) of the resin sheet 53 in the sheet flow direction (feeding direction). A large number of parallel stripe-like semi-elliptical ridges 17 are formed.

  Thereafter, the resin sheet 53 is conveyed with the surface 76 in close contact with the peripheral surface 68 of the lower roll 65. When the resin sheet 53 is pressed and conveyed, the surface temperature T (R3) of the lower roll 65 is Tg−30 ° C. ≦ T (R3) ≦ Tg + 50 ° C. when the glass transition temperature of the raw material resin is Tg, preferably , Tg−20 ° C. ≦ T (R3) ≦ Tg + 40 ° C. For example, when a polystyrene resin having a glass transition temperature Tg of 102 ° C. is used, the lower limit of the surface temperature T (R3) of the lower roll 65 is set to 72 ° C., and the upper limit is adjusted to 152 ° C.

If the surface temperature T (R3) of the lower roll 65 is in the above range, the semi-elliptical concave groove of the intaglio transfer mold 69 is prevented while preventing the occurrence of the “trailing phenomenon” in which the resin sheet 53 sticks to the intaglio transfer mold 69. The resin can be satisfactorily introduced to the tip of 70.
After the conveyance, the resin sheet 53 is peeled off from the lower roll 65 at the lower end of the lower roll 65 and sent out to the take-up roll group 55 in the horizontal direction. Thereafter, the resin sheet 53 is manufactured by being taken up by the pair of take-up rolls 85 and 86. Then, after the resin sheet 53 is further cooled, the light diffusion plate 10 can be obtained by cutting the resin sheet 53 with an appropriate size.

In addition, the conveyance speed (speed of the production line) V of the resin sheet 53 is, for example, 0.2 / T ₁ (m / min) ≦ V using the thickness T ₁ of the resin sheet 53 (light diffusion plate 10). ≦ 50 / T ₁ (m / min), preferably 0.3 / T ₁ (m / min) ≦ V ≦ 40 / T ₁ (m / min). If the conveyance speed V is in the above range, the resin sheet 53 can be produced in a relatively short cycle time while preventing the occurrence of the “trailing phenomenon” in which the resin sheet 53 adheres to the intaglio transfer mold 69, so that productivity is good. .
(4) Effects As described above, according to the present embodiment, the surface of the intaglio transfer mold 69 of the lower roll 65 is treated with organic polysiloxane. Thereby, the fine hole (micro crack) produced when the lower roll 65 is plated with chromium can be filled with the organic polysiloxane. Thereby, the wetting tension of the surface of the intaglio transfer mold 69 of the lower roll 65 is 35 mN / m or less. Therefore, even if the surface temperature T (R3) of the lower roll 65 is increased, it is possible to prevent the occurrence of the “trailing phenomenon” in which the resin sheet 53 adheres to the intaglio transfer mold 69. As a result, the lower roll 65 inlet temperature T (before R3) of the resin sheet 53 is Tg + 50 ° C. ≦ T (before R3) ≦ Tg + 160 ° C., and the surface temperature T (R3) of the lower roll 65 is Tg−30 ° C. ≦ T (R3) ≦ Tg + 50 ° C., and the conveyance speed V of the resin sheet 53 is 0.2 / T ₁ (m / min) ≦ V ≦ 50 / T ₁ (m / min). The resin can be satisfactorily penetrated to the tip of the elliptical groove 70. In addition, it is possible to prevent the occurrence of tack marks in the obtained resin sheet 53.

  Therefore, according to the present embodiment, the shape of the intaglio transfer mold 69 optimized by the optical design can be reproduced well as the semi-elliptical ridge 17 of the resin sheet 53. Therefore, the light diffusing plate 10 made of the resin sheet 53 can exhibit excellent optical characteristics. Moreover, if the optical film 4 is manufactured according to said method, the optical film 4 can express the outstanding optical characteristic.

That is, by using the manufacturing method disclosed in this embodiment, a highly difficult prism shape, which is difficult to transfer by the conventional manufacturing method, a high H ₁ ′ / P ₁ ′ ratio (0.5 or more), Even with a narrow pitch shape (30 μm or less), the transfer rate can be improved with high accuracy.
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented in other embodiment.

For example, instead of the intaglio transfer mold 69, an intaglio transfer mold 77 having a semicircular groove 78 having a substantially semicircular shape (cylindrical lens shape) shown in FIG. It is also possible to provide an intaglio transfer mold 79 having prism grooves 80 having a substantially prism shape (for example, apex angle θ is 60 ° to 120 °).
In the above-described embodiment, the shape roll provided with the intaglio transfer mold 69 is disposed as the lower roll 65, but may be disposed as the intermediate roll 64 as shown in FIG. In this case, the intermediate roll 64 inlet temperature T (before R2) is, for example, Tg + 50 ° C. ≦ T (before R2) ≦ Tg + 160 ° C., preferably Tg + 70 ° C. ≦ T, where Tg is the glass transition temperature of the raw material resin. (Before R2) It adjusts suitably so that it may become the range of <= Tg + 140 degreeC. The adjustment of the intermediate roll 64 inlet temperature T (before R2) is performed by setting the heater 72 so that the back surface 75 (the surface on the transfer side) of the resin sheet 53 extruded from the die 58 can be heated. This can be done by adjusting the output or adjusting the temperature of the cylinder 56.

  In the above-described embodiment, the back surface 18 of the light diffusing plate 10 and the back surface 23 of the optical film 4 are flat surfaces without unevenness. For example, the mat has fine unevenness after being embossed or the like. It may be a surface. In that case, the back surface 75 of the resin sheet 53 may be embossed. In order to emboss the back surface 75 of the resin sheet 53, for example, in the manufacturing apparatus 51 for the resin sheet 53, an embossed transfer mold may be provided on the peripheral surface 67 of the intermediate roll 64, and the transfer mold may be transferred.

Further, in the above-described embodiment, the press roll group 54 is configured such that the upper roll 63, the intermediate roll 64, and the lower roll 65 are arranged side by side in the vertical direction. The form arrange | positioned along with a direction may be sufficient.
Further, for example, a roll (touch roll) in contact with the resin sheet 53 and the intaglio transfer mold 69 is provided as long as the roll is irrelevant in terms of transfer technology for assisting conveyance or adhesion between the resin sheet 53 and the pressing rolls 63 to 65. May be.

Further, for example, the light diffusing plate (resin sheet) is not limited to a single layer resin plate like the light diffusing plate 10, for example, from a two-layer resin plate, a three-layer resin plate, four or more layers It may be a multi-layer resin plate.
Moreover, although the light diffusing plate 10 is used suitably as a light diffusing plate for backlights, it is not particularly limited to such an application.

The backlight system 2 is preferably used as a surface light source device for a liquid crystal display device, but is not particularly limited to such an application.
In addition, various design changes can be made within the scope of matters described in the claims.

Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example.
<Example 1>
The apparatus which has the structure similar to the resin sheet manufacturing apparatus shown in FIG. 1 was used. As the pressing roll, a mirror surface cooling roll having a surface plated with chromium was used as an upper roll and an intermediate roll. Further, as the lower roll, a shape roll in which the surface material is made of chrome, a concave lens shape (concave groove) is formed in the entire area of the surface in parallel with the roll rotation direction, and an organic polysiloxane treatment is performed. The pitch P ₁ of the intaglio transfer mold having a concave lens shape was 353 μm, and the depth H ₁ was 223.7 μm.

In the production of the resin sheet, first, a styrene resin (“HRM40” manufactured by Toyo Styrene Co., Ltd., Tg 102 ° C.) is supplied to an extruder having a screw diameter of 40 mm and melt-kneaded at a cylinder temperature of 210 ° C. to 260 ° C. Supplied to.
Next, the resin in the feed block was extruded into a sheet shape at a T die temperature of 250 ° C. to 260 ° C. via a T die having a width of 250 mm.

After that, the extruded resin sheet is sandwiched between an upper roll (mirror cooling roll) and an intermediate roll (mirror cooling roll) and conveyed while being wound around the surface of the intermediate roll, and an intermediate roll and a lower roll (transfer type mounting roll) And the resin sheet peeled off from the lower roll was taken up by the take-up roll. Accordingly, concave shape on a surface (upper surface) is transferred, the thickness T ₁ is to obtain a surface profile transfer resin sheet 2 mm. The sheet conveyance speed (line speed) was 0.65 m / min (0.2 / T ₁ to 50 / T ₁ ). Further, the temperature of the resin sheet before coming into contact with the lower roll (lower roll inlet temperature T (before R3)) was adjusted by a heater.

Then, the lower roll inlet temperature T (before R3) and the lower roll surface temperature T (R3) were changed, and the presence or absence of occurrence of a trail phenomenon in the production process under each condition was confirmed. Moreover, the cross section of the obtained resin sheet was observed with a microscope, and the shape transfer rate T was determined by measuring the height H ₁ ′ of the ridges.
Shape transfer rate T (%) = height of the ridge of the resin sheet H ₁ ′ / depth of the groove of the lower roll H ₁ × 100
Further, the wetting tension of the surface of the intaglio transfer mold of the lower roll was measured by the following method in accordance with JIS K 6768 and found to be 23 mN / m.

  Specifically, the test was conducted using “mixture for wetting tension test” (hereinafter, simply referred to as a chemical) manufactured by Wako Pure Chemical Industries, Ltd. First, the temperature of the intaglio transfer mold (work) was stabilized at around 23 ° C. Next, the surface of the intaglio transfer mold was wiped with a cloth soaked with ethanol. Next, a cotton swab was immersed in the chemical, and one drop of the chemical adhering to the cotton swab was placed on the intaglio transfer mold so as not to flow. And it determined 3 to 5 seconds after mounting a liquid. The determination was made by visually observing the placed liquid to determine whether “(1) the liquid is playing” or “(2) the liquid is wet”. The case where the liquid swelled and the size did not change was determined as (1), and the case where the liquid was flat and gradually spread was determined as (2).

After the determination, if the result is (1), the process proceeds to a chemical having a smaller numerical value (wetting tension), and if the result is (2), the process proceeds to a chemical having a larger numerical value (wetting tension). This operation was repeated to narrow down the wetting tension chemicals that can accurately wet the surface of the intaglio transfer mold, and the wetting tension of the chemicals was taken as the measurement result.
<Example 2>
As the lower roll (shape roll), the same process as in Example 1 was used except that the surface of the intaglio transfer mold was wiped with a cotton cloth after the organopolysiloxane treatment of Example 1 and the surface was washed. A resin sheet was prepared according to the methods and conditions described above.

Then, the lower roll inlet temperature T (before R3) and the lower roll surface temperature T (R3) were changed, and the presence or absence of occurrence of a trail phenomenon in the production process under each condition was confirmed. Moreover, the cross section of the obtained resin sheet was observed with a microscope, and the shape transfer rate T was determined by measuring the height H ₁ ′ of the ridges.
Further, the wetting tension of the surface of the intaglio transfer mold of the lower roll was measured by the same method as in Example 1 and found to be 23 mN / m.
<Comparative Example 1>
A resin sheet was produced by the same method and conditions as in Example 1 except that a roll not subjected to organic polysiloxane treatment was used as the lower roll (shape roll).

Then, the lower roll inlet temperature T (before R3) and the lower roll surface temperature T (R3) were changed, and the presence or absence of occurrence of a trail phenomenon in the production process under each condition was confirmed. Moreover, the cross section of the obtained resin sheet was observed with a microscope, and the shape transfer rate T was determined by measuring the height H ₁ ′ of the ridges.
Further, the wetting tension of the surface of the intaglio transfer mold of the lower roll was measured by the same method as in Example 1, and it was 42 mN / m.
<Example 3>
The apparatus which has the structure similar to the resin sheet manufacturing apparatus shown in FIG. 9 was used. As the pressing roll, a mirror surface cooling roll having a surface plated with chromium was used as the upper roll and the lower roll. Further, as the intermediate roll, a shape roll in which the surface material is made of chrome, a concave lens shape (concave groove) is formed in the entire area of the surface in parallel to the roll rotation direction, and an organic polysiloxane treatment is performed. The pitch P ₁ of the intaglio transfer mold having a concave lens shape was 353 μm, and the depth H ₁ was 223.7 μm.

In the production of the resin sheet, first, a polycarbonate resin (“Caliber 200-30” manufactured by Sumitomo Dow Co., Ltd., glass transition temperature Tg measured in accordance with JIS 7212-1987, Tg: 147 ° C.) is used as an extruder having a screw diameter of 40 mm. The mixture was melt-kneaded at a cylinder temperature of 210 ° C. to 260 ° C. and then supplied to the feed block.
Next, the resin in the feed block was extruded into a sheet shape at a T die temperature of 250 ° C. to 260 ° C. via a T die having a width of 250 mm.

After that, the extruded resin sheet is sandwiched between an upper roll (mirror cooling roll) and an intermediate roll (transfer mold mounting roll) and conveyed while being wound around the surface of the intermediate roll, and an intermediate roll and a lower roll (mirror cooling roll). And the resin sheet peeled off from the lower roll was taken up by the take-up roll. Accordingly, concave shape on a surface (lower surface) has been transferred, the thickness T ₁ is to obtain a surface profile transfer resin sheet 1.2 mm. The sheet conveyance speed (line speed) was 0.90 m / min (0.2 / T ₁ to 50 / T ₁ ).

And the intermediate roll inlet_port | entrance temperature T (before R2) was changed, and the presence or absence of generation | occurrence | production of the tray phenomenon in the manufacturing process of each condition was confirmed. Moreover, the cross section of the obtained resin sheet was observed with a microscope, and the shape transfer rate T was determined by measuring the height H ₁ ′ of the ridges.
Further, the wetting tension of the surface of the intaglio transfer mold of the intermediate roll was measured by the same method as in Example 1, and found to be 23 mN / m.
<Comparative example 2>
A resin sheet was produced by the same method and conditions as in Example 3 except that a roll not subjected to organic polysiloxane treatment was used as an intermediate roll (shape roll).

At the time of manufacture, the presence or absence of occurrence of a trail phenomenon in the manufacturing process was confirmed. Moreover, the cross section of the obtained resin sheet was observed with a microscope, and the shape transfer rate T was determined by measuring the height H ₁ ′ of the ridges.
Further, the wetting tension of the surface of the intaglio transfer mold of the lower roll was measured by the same method as in Example 1, and it was 42 mN / m.
<Evaluation>
(1) Shape transfer rate T and evaluation of the trail phenomenon The results of the shape transfer rate T and the trail phenomenon evaluation obtained in Examples 1 and 2 and Comparative Example 1 are shown in Table 1 below.

  Table 2 below shows the shape transfer rate T obtained in Example 3 and Comparative Example 2 and the results of evaluation of the trail phenomenon.

(2) IR (Infrared Spectroscopy) Analysis The infrared absorption spectrum of the transfer mold surface of the lower roll (shape roll) used in Examples 1-2 and Comparative Example 1 was measured by the ATR reflection method. The obtained IR spectrum is shown in FIG.
As shown in FIG. 10, the transfer mold surface of Example 1 showed a peak at the same wave number as the spectrum of the organopolysiloxane, but the transfer mold surface of Example 2 and Comparative Example 1 showed a peak. I couldn't see it. The reason why the peak was not observed in Example 2 is considered to be that the transfer mold surface was wiped with a cotton cloth, and this removed organic polysiloxane that could not fit into the fine holes of the chrome plating. .
(3) TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) Analysis A portion of the transfer mold surface of the lower roll (shape roll) used in Examples 1-2 and Comparative Example 1 was subjected to a TOF-SIMS apparatus. (Analyzed by Physical Electronics). The measurement conditions were as follows. The measurement results are shown in Table 3 below. Table 3 shows the result of normalizing the intensity of each positive ion mass spectrum so that the total positive ion mass spectrum is 1.
Irradiated primary ions: ⁶⁹ Ga ⁺
・ Measurement area: about 80 × 80μm ²
· The detected secondary _{ions: Positive (C 5 H 15 Si} 2 O + and _{C 7 H 21 Si 4 O 4} +)
-Detection mass range: 0.5-2000a. m. u

As shown in Table 3, compared to Example 2 and Comparative Example 1, the transfer type surface of Example 1 has positive ions (C ₅ H ₁₅ Si ₂ O ⁺ and C ₇ H ₂₁ Si derived from organic polysiloxane). ₄ O ₄ ⁺ ) was detected in large numbers. The reason why it was not detected in Example 2 is considered to be that the surface of the transfer mold was wiped with a cotton cloth, thereby removing the organic polysiloxane that could not fit into the fine holes of the chrome plating.

53 Resin sheet 58 Die 65 Lower roll 64 Intermediate roll 69 Intaglio transfer mold 76 (Resin sheet) surface 77 Intaglio transfer mold 79 Intaglio transfer mold

Claims (4)

A process of continuously extruding the resin from the die in a heated and melted state to form a continuous resin sheet;
By pressing the surface of the transfer mold against the surface of the continuous resin sheet using a shape roll having a transfer mold having a surface with a wetting tension of 35 mN / m or less measured according to JIS K 6768, And a step of transferring the shape of the transfer mold. A method for producing a surface shape transfer resin sheet.   The method for producing a surface shape transfer resin sheet according to claim 1, wherein a shape roll having a transfer mold in which an organic polysiloxane treatment is applied to the surface is used as the shape roll.   The method for producing a surface shape transfer resin sheet according to claim 2, wherein a shape roll having a transfer mold whose surface is washed after the treatment with the organic polysiloxane is used as the shape roll. When the glass transition temperature of the resin is expressed as Tg (° C.) and the thickness of the continuous resin sheet after transfer is expressed as T (mm),
The surface temperature of the shape roll is Tg-30 (° C.) to Tg + 50 (° C.), and the conveying speed of the continuous resin sheet is 0.2 / T (m / min) to 50 / T (m / min). The surface shape transfer according to any one of claims 1 to 3, wherein the surface temperature of the continuous resin sheet before contacting the shape roll is Tg + 50 (° C) to Tg + 160 (° C). Manufacturing method of resin sheet.

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