JPH10676A - Method for manufacturing sheet having uneven pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously stably obtain an amorphous thermoplastic resin sheet having a minute uneven pattern without thermal deterioration and thermal decomposition. SOLUTION: An amorphous thermoplastic resin heated and melted by an extruder 1 is extruded by a T-die 2 heated and set so that a temperature of a lip 21 is higher than a temperature except the lip and lower than a thermally decomposing temperature of the resin to a sheet 3. The sheet 3 is transferred and fastened between a metal roll 4 having an uneven pattern on a surface and a pressing roll 5, thereby transferring the pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an amorphous thermoplastic resin sheet having an uneven pattern on one side, and more particularly, to a method for emitting a light beam used in a planar light emitting device of a liquid crystal display material. The present invention relates to a method of manufacturing a precision molded sheet for optical use such as a lens sheet to be controlled.

2. Description of the Related Art Amorphous thermosetting sheets such as decorative sheets for building materials, stationery materials, and precision molded sheets for optical applications such as lens sheets for controlling the light emitting direction used in planar light emitting devices for liquid crystal display materials. Conventionally, a sheet having an uneven pattern on one side made of a plastic resin is conventionally extruded in a semi-molten state using a T-die, and is pressed between a metal roll having a predetermined uneven pattern on its surface and a pressing roll to form the uneven pattern. A method of forming with a mark is known and widely practiced (see, for example, JP-A-7-314567).

In the case where a fine uneven pattern is required, especially for a precision molded sheet for optical applications, the uneven pattern is sharply formed by the pinching pressure, and the formed uneven pattern is broken by the elasticity of the sheet. In order to avoid this, the temperature of the entire T-die is raised to near the thermal decomposition temperature of the amorphous thermoplastic resin, which is the material of the extruded sheet, so that the fluidity of the resin immediately before being pressed between the metal roll and the pressing roll Can be increased.

[0003]

However, if the temperature of the entire T-die is raised to near the thermal decomposition temperature of the amorphous thermoplastic resin, which is the raw material of the sheet, thermal degradation or thermal decomposition may occur. , It becomes impossible to manufacture continuously.

[0004] The present invention has been made in view of the above-mentioned problems of the prior art, and solves the problems of the prior art without causing thermal deterioration or thermal decomposition of the sheet. It is an object of the present invention to provide a method for producing a sheet having an uneven pattern, which can continuously and stably obtain a sheet having a fine uneven pattern.

[0005]

In order to achieve the above object, a method for producing a sheet having a concavo-convex pattern according to the present invention comprises:
An amorphous thermoplastic resin heated and melted by an extruder is extruded from a T-die heated at a lip temperature higher than the temperature other than the lip portion and lower than the thermal decomposition temperature of the resin, and has an uneven surface pattern. Is transferred between the metal roll and the pressing roll having the above, and the uneven pattern is transferred while being pressed.

[0006] The amorphous thermoplastic resin used in the present invention is not particularly limited as long as it can be extruded, and examples thereof include polyvinyl chloride, polystyrene, polycarbonate, and the like.
Examples include methacrylic resin.

In the T-die used in the present invention, it is necessary to heat the lip to a temperature higher than the temperature of other parts and lower than the pyrolysis temperature. It is necessary to have a heating means capable of heating. As such a heating means, a band heater using a heating wire such as a nichrome wire or a sheath heater is mounted or buried in the lip portion, or a heating medium circulation pipe or jacket such as heating oil is mounted on the lip portion or A buried one, a lip part by induction heating, and the like can be given.

In the present invention, the temperature slightly lower than the thermal decomposition temperature depends on the temperature of other portions of the T-die and the time required for the molten resin to pass through the lip portion. The temperature is 5 to 30C lower than the temperature, preferably 10 to 20C lower.

[0009] The uneven pattern on the surface of the metal roll used in the present invention, even if the pattern is directly engraved on the outer surface of the metal roll, the outer cylinder material with the pattern engraved on the surface is attached. May be provided. Also,
Examples of the method of engraving the pattern include a rolling method using a top mold, an engraving method, etching, sand blasting, lathe cutting, lathe grinding, and a combination thereof. It is preferable to apply hard chrome plating, nickel plating, etc. to the surface of the metal roll provided with the uneven pattern for the purpose of preventing damage. Is preferably applied.

Further, in order to precisely and sharply transfer the concavo-convex pattern formed on the surface of the metal roll to the surface of the resin, the surface temperature of the metal roll should be close to the glass transition temperature of the amorphous thermoplastic resin. It must be kept uniform and constant. Therefore, it is preferable that the metal roll is provided with a spiral flow passage for passing the cooling medium therein.

The pressing roll used in the present invention is not particularly limited. For example, a layer of natural rubber, neoprene, cross-linked silicone rubber or the like is formed on a metal core roll by a method such as an adhesive, casting or the like. The provided rubber roll is suitably used. In addition, it is preferable that the press roll also has a flow passage for passing a cooling medium inside.

In the present invention, the amorphous thermoplastic resin sheet to which the concave and convex pattern has been transferred is cooled to be a raw material product, but it is optional to perform an annealing treatment in order to remove distortion during sheet forming. . For example, a method in which the sheet is heated to a temperature equal to or higher than the glass transition temperature and equal to or lower than the softening temperature and annealed is used. Specifically, a method in which the sheet is pressure-bonded to one or more heating rolls, and an oven is heated. For example, a method of allowing the liquid to pass through is preferably performed.

(Function) The heat-melted amorphous thermoplastic resin passes through the lip locally heated to a temperature slightly lower than the thermal decomposition temperature in a short time. Therefore, the resin does not undergo thermal decomposition, and when the resin is sandwiched between the metal roll and the pressing roll, the uneven pattern on the surface of the metal roll is clearly transferred.

[0014]

Embodiments and examples of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an embodiment of the present invention. A T-die 2 is attached to the tip of the extruder 1. In the T die 2, only the lip portion 21 at the tip is heated to a temperature higher than the other portion and slightly lower than the pyrolysis temperature, and the other portion is heated to a plasticizing temperature suitable for molding the extruded amorphous thermoplastic resin. Heated.

When the amorphous thermoplastic resin heated and melted by the extruder 1 is extruded from the T-die 2, only the surface of the sheet 3 has sufficient fluidity so that the uneven pattern on the surface of the metal roll is clearly transferred. Is kept. Moreover, since the time during which the sheet 3 is heated to a temperature slightly lower than the thermal decomposition temperature is very short, the sheet 3 does not undergo thermal decomposition or thermal degradation.

Next, while moving the sheet 3 heated only to a temperature slightly lower than the thermal decomposition temperature at the surface portion, the temperature controlling oil is circulated through the spiral flow passage having an uneven pattern on the surface and the inside. The metal roll 4 and the rubber roll 5 that also circulates cooling water through the spiral flow passage inside the body 3 squeeze from both sides to transfer the uneven pattern of the surface of the metal roll 4 to one side of the sheet 3 and to make a glass transition. The intermediate sheet 7 is obtained by cooling to a temperature below the temperature, and further bringing the medium into contact with a metal cooling roll 6 in which the heat medium oil is circulated.

Further, the intermediate sheet 7 is passed through a strain removing device 8 in which a plurality of strain removing rolls 81,. Is removed, and the product sheet 10 having an uneven pattern on one side is obtained by taking it off with a take-off roll 9.

A specific embodiment will be described below. (Example) A polycarbonate resin (pyrolysis temperature: about 340 ° C.) heated and melted by an extruder 1 is extruded by a T-die 2 in which a temperature of a lip portion 21 is 330 ° C. and a temperature of other portions is 280 ° C. Thus, Sheet 3 before patterning was used.

The pre-patterned sheet 3 is provided with an isosceles triangular groove having a cross section of 100 μm at the bottom and 50 μm in height.
And a metal roll 4 engraved on the entire surface continuously in a saw-tooth shape in the roll axis direction and hard chrome plated thereon.
Then, a neoprene rubber having a thickness of 2 mm is adhered to the outer surface of the metal core roll, and a room-temperature-curable reactive silicone rubber is cast on the outer surface so as to have a thickness of 2 mm.
After curing at 3 ° C. for 3 hours, the entire surface was sandwiched by a rubber roll 5 polished with a buff (# 1000), and the uneven pattern on the surface of the metal roll 4 was transferred to obtain a patterned intermediate sheet 7. During this time, 130 ° C. heat medium oil was circulated inside the metal roll 4, and 50 ° C. cooling water was circulated inside the rubber roll 5.

Further, the intermediate sheet 7 is cooled by bringing it into contact with a cooling roll 6 in which a heat medium oil of 125 ° C. is circulated, and then a strain relief roll in which a heat medium oil of 110 ° C. is circulated. 81 and then annealed,
The product sheet 10 having a concave-convex pattern on one side was obtained by taking it off with a take-off roll 9.

(Comparative Example 1) A product sheet was obtained by the same method as that of the example except that the T-die heated the lip portion to non-heating and the temperature of the other portion to 280 ° C was used.

(Comparative Example 2) A product sheet was obtained in the same manner as in Example except that a T-die heated to 280 ° C was used for the lip portion and other portions.

(Comparative Example 3) A product sheet was obtained in the same manner as in the example except that the T-die heated the lip portion to non-heating and the temperature of the other portion to 330 ° C was used.

(Comparative Example 4) A product sheet was obtained in the same manner as in the example except that a T-die heated to 330 ° C. was used for both the lip portion and other portions.

Next, with respect to the product sheet having an uneven pattern on one surface obtained in the above-mentioned Example and Comparative Examples 1 to 4, the ratio of the depth of the uneven pattern of the product sheet to the height of the uneven pattern on the surface of the metal roll (addition). Shape transfer accuracy),
When a sheet having a concavo-convex pattern on one side was continuously molded for 200 hours, the quality of the concavo-convex pattern, the presence or absence of thermal decomposition or thermal deterioration, and the presence or absence of abnormalities in the molding operation (referred to as continuous formability) were evaluated. The results are summarized in Table 1.

[0026]

[Table 1]

[0027]

As is apparent from the above description, according to the method for producing a sheet having a concavo-convex pattern of the present invention, the amorphous thermoplastic resin passing through the T-die is kept at a temperature slightly lower than the thermal decomposition temperature. As it passes through the locally heated lip in a short time, only the surface of the extruded sheet before patterning has sufficient fluidity, and is pressed by the metal roll and the pressing roll. And the uneven pattern on the surface of the metal roll is clearly transferred and patterned. However, since the amorphous thermoplastic resin that passes through the T-die has a short passage time through the lip portion, the sheet having an uneven pattern accurately transferred to one side without causing thermal decomposition or thermal degradation can be used. It can be manufactured stably over time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an embodiment of the present invention.

[Explanation of symbols]

 2 T die 21 Lip part 3 Sheet before patterning 4 Metal roll 5 Rubber roll (pressing roll) 7 Intermediate sheet 8 Strain removing device 81 Strain removing roll 10 Product sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 11:00

Claims (1)

[Claims] 1. An amorphous thermoplastic resin heated and melted by an extruder, wherein a temperature of a lip portion is higher than a temperature of a portion other than the lip portion,
The resin is extruded from a T-die set at a temperature lower than the thermal decomposition temperature of the resin, transferred between a metal roll having an uneven pattern on the surface thereof and a pressing roll, and the uneven pattern is transferred while being pressed. A method for producing a sheet having a pattern.