JP2011194725A - Method for manufacturing surface shape transfer resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a surface shape transfer resin sheet which can transfer the uneven shape of the surface of the resin sheet at a high rate of transfer.SOLUTION: The method comprises (1) an extrusion process to obtain a continuous resin sheet 2 by continuously extruding a resin from a die 8, and (2) a first pressing process which inserts the continuous resin sheet 2 between a first pressing roll 11 and a second pressing roll 12. In addition. a transfer mold is mounted to the surface of the second pressing roll 12, and the transfer mold has a plurality of recessed grooves with pitch intervals of 30 to 500 μm and groove depths of 3 to 500 μm. In the first pressing process, a melt bank 3 of the resin is formed between the first pressing roll 11 and the second pressing roll 12. Furthermore, the height E of the bank 3 is set not less than 3 times the thickness F of the continuous resin sheet 2, and the temperature of the second pressing roll 12 is set 10 to 50°C higher than the glass transition temperature Tg(°C) of the resin.

Description

  The present invention relates to a method for producing a surface shape transfer resin sheet capable of transferring an uneven shape to the surface of a resin sheet at a high transfer rate.

  As a method for producing a resin sheet having a concavo-convex shape on its surface, a method is known in which the shape of a transfer mold on the surface of a pressing roll is transferred to a continuous resin sheet obtained by extruding a resin from a die of an extruder (Patent Document 1). reference). That is, after the continuous resin sheet continuously extruded from the die is sandwiched between the first pressing roll and the second pressing roll, the continuous resin sheet is conveyed in close contact with the second pressing roll, and then the second pressing roll It is sandwiched between the third pressing roll. At this time, a transfer mold is provided on the surface of the second pressing roll, and the uneven shape of the transfer mold is transferred to the surface of the continuous resin sheet when sandwiched between the first pressing roll and the second pressing roll. Thus, the surface shape transfer resin sheet is manufactured.

Japanese Patent Laid-Open No. 9-11328

  However, in the technique described in Patent Document 1, the depth of the V-shaped groove formed in the transfer mold of the pressure roll is 40 μm, whereas the height of the hook-shaped pattern formed by the transfer is 2 to 15 μm. (See Examples 1 to 4 in Table 1 of paragraph 0022 of Cited Document 1), the transfer rate was about 5 to 37.5% and the transfer rate was low. That is, there is a problem that the uneven shape of the transfer roll cannot be transferred at a high transfer rate.

  The present invention has been made in view of such a technical background, and an object thereof is to provide a method for producing a surface shape transfer resin sheet capable of transferring a concavo-convex shape to a surface of a resin sheet at a high transfer rate. To do.

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

[1] An extrusion step of continuously extruding a resin from a die in a heated and melted state to obtain a continuous resin sheet;
Including a first pressing step of sandwiching the continuous resin sheet between a first pressing roll and a second pressing roll,
A transfer mold is provided on the surface of the second pressing roll, the transfer mold has a plurality of concave grooves, the pitch interval of the concave grooves is 30 μm to 500 μm, and the groove depth of the concave grooves is 3 μm to 500 μm. Yes,
In the first pressing step, a resin melt bank is formed between the first pressing roll and the second pressing roll, and the height of the melt bank is determined by the thickness of the continuous resin sheet extruded from the die. Set to more than 3 times
A method for producing a surface shape transfer resin sheet, characterized in that the temperature of the second pressing roll is set to a temperature higher by 10 ° C to 50 ° C than the glass transition temperature Tg (° C) of the resin.

  [2] The method for producing a surface shape transfer resin sheet according to item 1 above, wherein a thermoplastic resin is used as the resin.

  [3] The method for producing a surface shape transfer resin sheet according to item 2, wherein the thermoplastic resin is a polycarbonate resin.

  [4] When the length of a forming line forming one groove in the cross-sectional shape of the groove of the transfer mold is “L” and the pitch interval of the grooves is “P”, L / P is 1. 5. The method for producing a surface shape transfer resin sheet according to any one of items 1 to 3, which is 5 to 5.

  [5] Any one of items 1 to 4 above, wherein a cross-sectional shape of the groove of the transfer mold is substantially V-shaped, and an opening angle of the bottom of the substantially V-shaped groove is 10 ° to 80 °. The manufacturing method of the surface shape transcription | transfer resin sheet of description.

[6] After the first pressing step, a conveying step of conveying the continuous resin sheet in a state of being in close contact with the second pressing roll;
The manufacturing of the surface shape transfer resin sheet according to any one of the preceding items 1 to 5, further comprising a second pressing step of sandwiching the continuous resin sheet between the second pressing roll and the third pressing roll after the conveying step. Method.

  In the invention of [1], the height of the melt bank of the resin provided between the first pressing roll and the second pressing roll is set to three times or more the thickness of the continuous resin sheet extruded from the die. Since the uneven shape of the transfer mold can be transferred at a high transfer rate, and the temperature of the second pressing roll is set to a temperature 10 ° C. to 50 ° C. higher than the glass transition temperature Tg (° C.) of the resin, higher transfer Can be transferred at a rate.

  In the invention of [2], since the thermoplastic resin is used as the resin, the uneven shape of the transfer mold can be transferred at a higher transfer rate.

  In the invention of [3], since a polycarbonate resin is used as the resin, there is an advantage that it is excellent in transparency, impact resistance and heat resistance.

  In the invention of [4], the transfer mold is provided with a sharp and deep groove shape having an L / P value of 1.5 to 5. Even in such a case, the uneven shape of the transfer mold is high. Can be transferred at a transfer rate.

  In the invention of [5], the cross-sectional shape of the transfer-type groove is substantially V-shaped, and the opening angle of the bottom of the substantially V-shaped groove is set to 10 ° to 80 °. The surface shape transfer resin sheet having a plurality of ridges (prisms) having a substantially triangular shape can be manufactured with good transferability.

  In the invention of [6], after the first pressing step, the conveying step of conveying the continuous resin sheet in close contact with the second pressing roll, and after the conveying step, the continuous resin sheet and the second pressing roll Since the second pressing step sandwiched between the three pressing rolls is further provided, the sheet surface can be smoothed.

It is the schematic which shows an example of the manufacturing apparatus used with the manufacturing method of this invention. It is explanatory drawing of the definition of the height of a melt bank. It is an expanded sectional view of the transfer mold on the surface of the second pressing roll (a sectional view cut along a plane including the rotation center axis of the roll). It is sectional drawing (sectional drawing of the VV line in FIG. 1) which shows one Embodiment of the surface shape transcription | transfer resin sheet manufactured with the manufacturing method of this invention. (A) (b) is an expanded sectional view (cross-sectional view cut | disconnected by the plane containing the rotation center axis | shaft of a roll) which shows the modification of a transfer type | mold. It is explanatory drawing of a bank mark.

  The manufacturing method of the surface shape transfer resin sheet 1 according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a manufacturing apparatus used in this manufacturing method. This manufacturing apparatus includes an extruder 7 provided with a die 8, a first pressing roll 11, a second pressing roll (transfer roll) 12, and a first pressing roll 11 arranged side by side at a front position in the extrusion direction of the extruder 7. Three pressing rolls 13 are provided. The second pressing roll 12 is disposed at a position directly below the first pressing roll 11, and the third pressing roll 13 is disposed at a position immediately below the second pressing roll 12. The outer peripheral surface of the first pressing roll 11 is formed into a mirror surface, and the outer peripheral surface of the third pressing roll 13 is formed into a mirror surface. A plurality of concave grooves 22 a are formed on the outer peripheral surface of the second pressing roll 12, that is, the second pressing roll 12 includes a transfer mold 22 on the surface thereof.

  FIG. 3 shows an enlarged cross-sectional view of the transfer die 22 provided on the surface of the second pressing roll 12 (enlarged cross-sectional view cut along a plane including the rotation center axis of the second pressing roll). As described above, a large number of concave grooves 22a having a substantially V-shaped cross section (a curved surface in which the inclined surfaces of the grooves bulge outward) 22a are formed on the surface of the second pressing roll 12 along the rotation direction of the roll 12. Has been. The groove 22a of the transfer mold 22 contacts the surface (the lower surface in FIG. 1) of the continuous resin sheet 2 continuously extruded from the die 8 of the extruder 7, and the cross-sectional shape is substantially on the contacted surface. A V-shaped ridge portion 32 (a curved surface having an inclined surface bulging outward) is formed.

  The surface shape transfer resin sheet 1 is manufactured as follows using the above manufacturing apparatus.

[Extrusion process]
Resin is continuously extruded from the die 8 in a heated and melted state to obtain a continuous resin sheet 2 (see FIG. 1).

  As the die 8 for continuously extruding the resin in a heated and melted state, a metal T-die similar to that used in a normal extrusion method is used. In order to extrude the resin from the die 8 in a heated and melted state, an extruder 7 is used as in a normal extrusion molding method. The extruder 7 may be a single screw extruder or a twin screw extruder. The resin is heated in the extruder 7 and sent to the die 8 in a molten state and extruded. The resin extruded from the die 8 is continuously extruded in the form of a sheet and becomes a continuous resin sheet 2.

  The continuous resin sheet 2 may be a single layer or two or more layers. When the continuous resin sheet 2 is a single layer, when the resin is extruded from the die 8 in a heated and melted state, one type of resin may be supplied to the die 8 and extruded, and in the case of two or more layers, two types The above resin may be supplied to the die and coextruded in a laminated state. In order to perform co-extrusion in a state where two or more kinds of resins are laminated, for example, a known two-type three-layer distribution type feed block or a multi-manifold die is used, and the resin is supplied to the die 8 via this. It ’s fine.

  The thickness F of the continuous resin sheet 2 may be appropriately adjusted according to the use of the obtained surface shape transfer resin sheet 1. For example, when the continuous resin sheet 2 is used as a light diffusion plate, the thickness F of the continuous resin sheet 2 is 0.1. It is preferable to set in the range of -3.0 mm, and it is more preferable to set in the range of 0.2-2.0 mm.

  Although it does not specifically limit as said resin, Usually, the thermoplastic resin which will be in a molten state by heating is used. The thermoplastic resin is not particularly limited. For example, styrene resin, acrylic resin, polyethylene, polypropylene, cyclic olefin polymer resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), Examples thereof include polyethylene terephthalate (PET) and polycarbonate (PC). Among them, it is preferable to use a polycarbonate resin as the thermoplastic resin in terms of excellent transparency, impact resistance, heat resistance, dimensional stability, and workability. In addition, the thermosetting resin which hardens | cures by heating can also be used in the range applicable to the manufacturing method of this invention.

  Additives such as a light diffusing agent, an ultraviolet absorber, a heat stabilizer, and an antistatic agent may be added to the resin.

  The light diffusing agent may be an inorganic light diffusing agent or an organic light diffusing agent. The inorganic light diffusing agent is not particularly limited. For example, calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, inorganic glass, talc, mica, white carbon, magnesium oxide, zinc oxide, and the like. And inorganic compound particles. The inorganic light diffusing agent may be surface-treated with a surface treatment agent such as fatty acid.

  The organic light diffusing agent is not particularly limited, and examples thereof include organic compound particles such as styrene polymer particles, acrylic polymer particles, and siloxane polymer particles.

  When adding the light diffusing agent, the absolute value of the difference between the refractive index of the added light diffusing agent and the refractive index of the resin is usually 0.02 or more from the viewpoint of sufficiently ensuring the light diffusing effect, From the viewpoint of sufficiently ensuring the light transmittance of the obtained surface shape transfer resin sheet, it is usually 0.13 or less. Thus, when a light-diffusion agent is added to resin, the surface shape transfer resin sheet 1 obtained can be used as a light-diffusion board, for example.

[First pressing step]
Next, as shown in FIG. 1, the continuous resin sheet 2 is inserted between the first pressing roll 11 and the second pressing roll 12 that are disposed at the front position in the extrusion direction of the extruder 7, and both pressing is performed. The continuous resin sheet 2 is pinched by the rolls 11 and 12. At this time, since the transfer mold 22 is provided on the surface of the second pressing roll 12, the cross-sectional shape is substantially V-shaped (the curved surface with the inclined surface bulging outward) on one surface of the continuous resin sheet 2. A certain ridge portion 32 is transferred (see FIG. 4). The ridge 32 extends along the conveying direction (extrusion direction) of the continuous resin sheet 2.

  In the first pressing step, the resin melt bank 3 is formed between the first pressing roll 11 and the second pressing roll 12 and the height E of the melt bank 3 is extruded from the die 8. It is set to 3 times or more the thickness F of the sheet 2 (see FIG. 2). Thus, by setting the height E of the melt bank 3 to 3 times or more the thickness F of the continuous resin sheet 2, the uneven shape of the transfer mold 22 can be transferred to the continuous resin sheet 2 at a high transfer rate. . In addition, it is preferable that the height E of the melt bank 3 is less than 15 mm. When it is 15 mm or more, the bank mark 91 as shown in FIG. 6 appears on the surface of the sheet opposite to the transfer surface (the surface on which the protrusions 32 are formed), which is not preferable.

  The height E of the melt bank 3 is an imaginary line K (second press roll) connecting the highest position of the melt bank 3 (position farthest from the rotation center of the second press roll 12) and the rotation center of the second press roll 12. 12 is a distance from the upper surface position of the continuous resin sheet 2 (the upper surface position of the portion corresponding to the thickness F of the sheet 2) to the highest upper surface position of the melt bank 3. (See FIG. 2).

  The height E of the melt bank 3 can be adjusted, for example, by adjusting the amount of resin extrusion, the extrusion line speed, the distance between the first pressing roll 11 and the second pressing roll 12, and the like. For example, the height E of the melt bank 3 is increased by means such as increasing the extrusion amount of the resin, decreasing the extrusion line speed, or narrowing the interval between the first pressing roll 11 and the second pressing roll 12. Can do. Further, for example, the height E of the melt bank 3 is reduced by means such as reducing the resin extrusion amount, increasing the extrusion line speed, or increasing the distance between the first pressing roll 11 and the second pressing roll 12. Can be set.

  In the first pressing step, the temperature of the second pressing roll 12 is set to a temperature 10 ° C. to 50 ° C. higher than the glass transition temperature Tg (° C.) of the resin constituting the continuous resin sheet 2. At a temperature lower than (Tg + 10) ° C., the uneven shape of the transfer mold 22 cannot be transferred at a high transfer rate. Further, at a temperature higher than (Tg + 50) ° C., the sheet 2 may stick to the second pressing roll 12. Especially, it is preferable to set the temperature of the 2nd press roll 12 to 15 to 35 degreeC higher than the glass transition temperature Tg (degreeC) of the said resin.

  Although the temperature of said 1st press roll 11 is not specifically limited, It is good to set to 80 to 150 degreeC.

  As said 1st press roll 11 and said 2nd press roll 12, normally, the metal roll comprised with metal materials, such as stainless steel and steel, is used, and the diameter is 100-500 mm normally. When a metal roll is used as the first pressing roll 11 and / or the second pressing roll 12, the surface thereof may be subjected to plating treatment such as chrome plating, copper plating, nickel plating, nickel-phosphorus plating, etc. good.

[Conveying process]
Next, the continuous resin sheet 2 that has undergone the first pressing step is conveyed in a state of being in close contact with the outer peripheral surface of the second pressing roll 12 (see FIG. 1). In this transporting process, the continuous resin sheet 2 is transported following the rotation of the second pressing roll 12.

  In the first pressing step and the transporting step, the continuous resin sheet has a temperature higher than that of the heated and melted state extruded from the die 8 due to cooling due to contact with the pressing rolls 11 and 12 or cooling due to contact with outside air. descend. Thus, the continuous resin sheet 2 is conveyed in a state where the temperature is lower than the heated and melted state immediately after extrusion, and is supplied to the next second pressing step. In addition, it is desirable that the first and second pressing rolls 11 and 12 have a temperature adjustment function and can be adjusted to a desired temperature.

[Second pressing step]
Next, the continuous resin sheet 2 that has undergone the transporting process is inserted between the second pressing roll 12 and the third pressing roll 13, and the continuous resin sheet 2 is sandwiched between the pressing rolls 12 and 13.

  As said 3rd press roll 13, the metal roll comprised with metal materials, such as stainless steel and steel, is normally used, and the diameter is 100-500 mm normally. When a metal roll is used as the third pressing roll 13, the surface thereof may be subjected to plating treatment such as chrome plating, copper plating, nickel plating, nickel-phosphorus plating, or the like. The third pressing roll 13 preferably has a temperature adjustment function and can be adjusted to a desired temperature.

  After the second pressing step, the continuous resin sheet 2 is conveyed while being in close contact with the surface of the third pressing roll 13, that is, the continuous resin sheet 2 is conveyed following the rotation of the third pressing roll 13. Thereafter, usually, cooling is further performed to obtain a surface shape transfer resin sheet 1 (see FIG. 4) on which one surface has the uneven shape of the transfer mold 22 transferred at a high transfer rate.

  According to this manufacturing method, the length of the forming line that forms one groove 22a in the cross-sectional shape of the concave groove 22a of the transfer mold 22 (cross-sectional shape cut along a plane including the rotation center axis of the second pressing roll 12). Is “L” and the pitch interval of the concave grooves 22a is “P” (see FIG. 2), the concave grooves 22a have a deep shape such that L / P is 1.5 to 5. Even in some cases, it is possible to manufacture the surface shape transfer resin sheet 1 in which the uneven shape of the transfer mold 22 is transferred at a high transfer rate.

  The surface shape transfer resin sheet 1 thus obtained is usually cut into single sheets and used, for example, as a prism sheet constituting a liquid crystal display device. Moreover, when what added the light-diffusion agent as resin is used, it can use suitably as a light-diffusion board.

  In this manufacturing method, the pitch interval P of the concave grooves 22a in the transfer mold 22 is usually set to 30 μm to 500 μm. Further, the groove depth D of the concave groove 22a in the transfer mold 22 is usually set in a range of 3 μm to 500 μm. In the transfer mold 22, adjacent concave grooves are usually provided in parallel with an interval d (see FIG. 3). The pitch interval P and the groove depth D of the concave grooves 22a are not necessarily constant throughout the entire transfer mold, and may be different between adjacent concave grooves.

  The interval d may be arbitrarily set depending on the use of the obtained surface shape transfer resin sheet, but the interval d is usually set to 10 μm or less. A configuration in which the distance d is not provided (that is, d = 0) may be employed.

  As the cross-sectional shape of the transfer die 22, in addition to the substantially V-shaped groove shown in FIG. Although the cross-sectional shape etc. which are included in a part can be illustrated, it is not limited to such a cross-sectional shape in particular.

  The opening angle θ (vertical angle θ) of the bottom of the substantially V-shaped groove 22a is normally 160 ° or less. However, according to this manufacturing method, the opening angle θ of the bottom of the substantially V-shaped groove 22a is Even in the case of a sharp groove shape of 10 ° to 80 °, the uneven shape of the transfer mold 22 can be transferred at a high transfer rate.

  The substantially semicircular concave groove may have, for example, a shape that is an arc shape in any of the cross sections when the cylindrical body is cut in a plane that is parallel to the central axis and does not include the central axis. Alternatively, the cross section may be a semi-elliptical arc shape or a flat curved shape that is a part of the semi-elliptical arc shape. Further, the case of adopting a shape having a substantially semicircular groove in which the substantially semicircular groove is inverted or a shape formed by a curve other than an elliptical arc shape is also included in the scope of claims of the present application. Further, the substantially semicircular concave groove may be, for example, a concave groove 22a having a cross-sectional shape shown in FIG. 5A or a curved cross-sectional shape as shown in FIG. 5B. The groove 22a may be used. The “substantially semicircular concave groove” includes such a concave groove having a substantially semicircular cross section.

  The transfer mold 22 is produced by applying a plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating, etc. to the surface of a transfer roll made of stainless steel, steel, etc. Examples thereof include a removal process using a diamond tool, a metal grindstone and the like, a laser process, a chemical etching method, and the like, but are not particularly limited to these techniques.

  Further, the surface of the second pressing roll (transfer roll) 12 is made of, for example, chromium plating, copper plating, nickel plating, nickel-phosphorous plating, etc. at a level that does not impair the accuracy of the surface shape after the transfer mold 22 is formed. Plating treatment may be performed.

  In addition, if it is a range which does not inhibit the effect of this invention, you may manufacture using the manufacturing apparatus of the structure which provided another roll other than said 1st, 2nd, 3rd press roll 11,12,13. . Examples of the other rolls include a guide roll (touch roll) for conveying the continuous resin sheet 2 to the first pressing roll 11 and a touch roll for keeping the continuous resin sheet 2 in close contact with the second pressing roll 12. Etc.

  Moreover, in the said embodiment, although the transfer type | mold 22 was provided only in the 2nd press roll 12, it is not limited to such a structure in particular, For example, the 2nd press roll 12 and the 3rd press roll 13 are included. Alternatively, the transfer mold 22 may be provided on both of them.

  In addition, the manufacturing method of the surface shape transfer resin sheet according to the present invention is not particularly limited to the above-described exemplary embodiment, and any design is within the scope of the claims as long as it does not depart from the spirit. Change is allowed.

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

(Manufacturing equipment A)
A manufacturing apparatus A having the configuration shown in FIG. 1 was prepared. The manufacturing apparatus A includes an extruder 7 provided with a T die 8, a first pressing roll 11, a second pressing roll 12, and a third pressing roll 13. The surface of the 1st press roll 11 and the 3rd press roll 13 is a mirror surface.

  As shown in FIG. 3, the second pressing roll 12 has a transfer die 22 having a plurality of concave grooves 22a on the surface. In the transfer mold 22 on the surface of the second pressing roll 12, the pitch interval P of the concave grooves 22a is 100 μm, the depth D of the concave grooves 22a is 105 μm, and the length of the forming line that forms one concave groove 22a in the cross-sectional shape. L is 232 μm, L / P = 2.32, the distance d is 5 μm, and the angle θ is 51 ° (see FIG. 3).

<Example 1>
A polycarbonate resin (“PC200-30” manufactured by Sumitomo Dow, glass transition temperature Tg measured in accordance with JIS K7121-1987) is supplied to the extruder 7 having the screw diameter of 40 mm of the manufacturing apparatus A and is supplied to the T die. 8 to obtain a continuous resin sheet 2 having a thickness F of 0.8 mm (extrusion process).

  Next, as shown in FIG. 1, the continuous resin sheet 2 is inserted between the first pressing roll 11 and the second pressing roll 12 of the manufacturing apparatus A, and the continuous resin sheet 2 is sandwiched between the pressing rolls 11 and 12. After pressing (first pressing step), the continuous resin sheet 2 is conveyed in a state of being in close contact with the outer peripheral surface of the second pressing roll 12 (conveying step), and then the continuous resin sheet 2 is transferred to the second pressing roll 12 and the third. After inserting between the pressing rolls 13 and sandwiching the continuous resin sheet 2 between the pressing rolls 12 and 13 (second pressing process), the cooling speed is 0.90 m / min while cooling with a cooling roll (not shown). By pulling, a surface shape transfer resin sheet 1 having a thickness S of 0.8 mm was obtained (see FIG. 4).

  At this time, the temperature of the second pressing roll 12 is set to 180 ° C., the temperature of the first pressing roll 11 is set to 130 ° C., and the temperature of the third pressing roll 13 is set to 150 ° C. 12 was formed so that the melt bank 3 of the resin was formed so that the height E of the melt bank was 6.0 mm (see FIG. 2), and the surface shape transfer resin sheet 1 was manufactured.

<Example 2>
Using a polycarbonate resin (“PC200-13” manufactured by Sumitomo Dow, glass transition temperature Tg measured in accordance with JIS K7121-1987) as the resin, the temperature of the second pressing roll 12 is set to 185 ° C., A surface shape transfer resin sheet 1 having a thickness S of 1.2 mm was obtained in the same manner as in Example 1 except that the thickness F of the continuous resin sheet 2 was set to 1.2 mm (see FIG. 4).

<Comparative Example 1>
The thickness S is 0.8 mm in the same manner as in Example 1 except that the melt bank height E is adjusted to 1.5 mm by reducing the number of revolutions per unit time of the screw of the extruder 7. The surface shape transfer resin sheet 1 was obtained.

<Comparative example 2>
The thickness S is 1.2 mm as in Example 2, except that the melt bank height E is adjusted to 1.5 mm by reducing the number of revolutions of the screw of the extruder 7 per unit time. The surface shape transfer resin sheet 1 was obtained.

  Next, the transfer rate in the surface shape transfer resin sheet obtained as described above was evaluated based on the following evaluation method. These evaluation results are shown in Table 1.

<Transfer rate evaluation method>
When the height of the protrusion 32 of the obtained surface shape transfer resin sheet is “H” (see FIG. 4) and the depth of the transfer groove 22a is “D” (see FIG. 3),
Transfer rate (%) = (H / D) × 100 (1)
The transfer rate is obtained by the above formula (1).

  As is clear from Table 1, the surface shape transfer resin sheets of Examples 1 and 2 manufactured by the manufacturing method of the present invention were transferred with a high transfer rate due to the uneven shape of the transfer mold. In Examples 1 and 2, the second pressing roll has an L / P of 2.32 and a transfer mold having a deep sharp concavo-convex shape. Were transferred at a high transfer rate of 91.6% and 90.0%.

  On the other hand, in Comparative Examples 1 and 2, where the height of the melt bank was less than three times the thickness of the continuous resin sheet, the transfer rates were 81.3% and 74.1%, respectively, and the transfer rate was low. It was.

  Since the surface shape transfer resin sheet manufactured by the manufacturing method of the present invention is transferred with a high transfer rate due to the concavo-convex shape of the transfer mold, for example, an optical element such as a prism sheet, a light diffusion plate, a light deflection structure plate, a light guide plate, etc. Although used suitably as a sheet | seat, it is not specifically limited to such a use. Among them, it is particularly suitable as an optical sheet for an image display device such as a liquid crystal display device.

DESCRIPTION OF SYMBOLS 1 ... Surface shape transfer resin sheet 2 ... Continuous resin sheet 3 ... Melt bank 7 ... Extruder 8 ... Die 11 ... 1st press roll 12 ... 2nd press roll 13 ... 3rd press roll 22 ... Transfer die 22a ... Groove E ... height F of melt bank ... thickness D of continuous resin sheet ... depth L of concave groove ... length P of formation line forming one concave groove in the sectional shape of the concave groove ... pitch interval? Opening angle of the bottom of the groove

Claims (6)

An extrusion process of continuously extruding the resin from the die in a heated and molten state to obtain a continuous resin sheet;
Including a first pressing step of sandwiching the continuous resin sheet between a first pressing roll and a second pressing roll,
A transfer mold is provided on the surface of the second pressing roll, the transfer mold has a plurality of concave grooves, the pitch interval of the concave grooves is 30 μm to 500 μm, and the groove depth of the concave grooves is 3 μm to 500 μm. Yes,
In the first pressing step, a resin melt bank is formed between the first pressing roll and the second pressing roll, and the height of the melt bank is determined by the thickness of the continuous resin sheet extruded from the die. Set to more than 3 times
A method for producing a surface shape transfer resin sheet, characterized in that the temperature of the second pressing roll is set to a temperature that is 10 to 50 ° C higher than the glass transition temperature Tg (° C) of the resin.   The method for producing a surface shape transfer resin sheet according to claim 1, wherein a thermoplastic resin is used as the resin.   The method for producing a surface shape transfer resin sheet according to claim 2, wherein the thermoplastic resin is a polycarbonate resin.   When the length of a forming line forming one groove in the cross-sectional shape of the transfer groove is “L” and the pitch interval of the grooves is “P”, L / P is 1.5 to 5 The method for producing a surface shape transfer resin sheet according to any one of claims 1 to 3.   The cross-sectional shape of the groove of the transfer mold is substantially V-shaped, and the opening angle of the bottom of the substantially V-shaped groove is 10 ° to 80 °. Manufacturing method of surface shape transfer resin sheet. After the first pressing step, a conveying step for conveying the continuous resin sheet in a state of being in close contact with the second pressing roll;
The surface shape transfer resin sheet according to any one of claims 1 to 5, further comprising a second pressing step of sandwiching the continuous resin sheet between the second pressing roll and a third pressing roll after the conveying step. Production method.

Images