JP2009166488A - Method for producing resin sheet, optical film, and apparatus for producing resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shape a fine, at least two-dimensional uneven pattern to be good in transfer properties. <P>SOLUTION: In a method for producing a resin sheet, a thermoplastic resin is extruded into a sheet, and the sheet is made to pass between an endless metal belt 6 hung on at least two rolls having parallel axial lines and a pressurization metal roll 3 while being pinched/pressed to shape the uneven pattern on at least one side of a sheetlike resin material. The at least two-dimensional uneven optical pattern is applied to the endless metal belt 6 and/or the pressurization metal roll 3. Just before the sheetlike resin material is pinched/pressed, the surface part of the sheetlike resin material is heated by infrared heaters (heaters 7 and 8) emitting infrared rays whose peak wavelength is about 2-3.8 μm. The sheetlike resin material is pinched/pressed between the endless metal belt 6 and the pressurization metal roll 3. A pinching/pressing distance is made at least 70 mm, and the uneven pattern is shaped on the surface of the heated sheetlike resin material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical member constituting a display such as a notebook computer or a liquid crystal TV. More specifically, the molten resin is extruded into a sheet shape, and the obtained sheet is passed while being pressed between a metal endless belt and a metal roll. Thus, the present invention relates to a method for producing an optical sheet in which a concave-convex pattern of a metal endless belt or a metal roll is shaped.

  In recent years, color liquid crystal display devices have been widely used in various fields such as notebook personal computers, desktop monitors, medium-sized to small-sized liquid crystal TVs, and the like. A liquid crystal display device is basically composed of a backlight and a liquid crystal display device element, and the backlight is a direct light system in which a light source is provided directly under the liquid crystal display element or an edge light in which a light source is provided on the side of a light guide. There is a method.

  The liquid crystal display device has advantages such as lower power consumption compared to other display devices, but there is a demand for reduced power consumption of the backlight. Improvement is required. As means for realizing these, a backlight system has been proposed in which an optical concavo-convex pattern sheet in which a large number of lens units such as prism rows and lenticular rows are formed on one side is mounted on a light guide.

  The optical concavo-convex pattern sheet improves the front luminance by controlling the light emitted from the backlight in the front direction by refraction.

  As shown in FIGS. 10 and 11 (FIGS. 10 and 11 are the same shape), the basic shape of the optical concavo-convex pattern sheet is such that the truncated cone shape is arranged with a period on one side of the sheet, or as shown in FIG. For example, an isosceles triangular prism.

  The optical concavo-convex pattern sheet needs to be colorless and transparent from an optical point of view, and the material is cycloolefin resin, acrylic resin, styrene resin, polycarbonate resin, β-pinene resin, UV curable resin. It is preferable that the material has excellent moldability.

  In order to manufacture the optical uneven pattern sheet, a hot press molding method to a flat plate, an ultraviolet curable resin method, an injection molding method, an extrusion roll molding method, an extrusion belt molding method and the like are used.

  The hot press molding method to a flat plate has a problem that a molding cycle is generally long and productivity is low because processes such as heating, shaping, and cooling of a sheet material are completed inside one press.

  The ultraviolet curable resin method is a method for easily forming an uneven pattern accurately. This is because, since the properties of the shaping resin are liquid, it is easy to enter the deep part of the concave and convex grooves of the mold, and thereafter ultraviolet rays are irradiated to cause a curing reaction.

  However, since the ultraviolet curable resin method involves a curing reaction, there is a problem that some unreacted substances remain and cause odor. In addition, the ultraviolet curable resin method has a problem in terms of cost because the resin material is limited, the material price is expensive, and the production speed cannot be increased.

  In order to manufacture a particularly thin and large-area optical member by the injection molding method, a large new equipment with a high injection pressure is required. However, even when a molded body can be manufactured, there is a problem that twisting or distortion due to residual strain during molding occurs, and it is actually difficult to use as a member.

  Since the extrusion roll forming method does not involve the chemical reaction as described above, there is almost no unreacted residue and odor due to this. That is, any resin can be used in this method as long as it is a thermoplastic resin. However, this method has the following problems.

  That is, in this extrusion roll forming method, since the resin is continuously sandwiched between the shaping roll subjected to the unevenness processing and the pressure roll, and simultaneously cooled, the unevenness is instantly formed. Since the shaping roll and the pressure roll are cylindrical, the area for narrowing the resin sheet is almost line contact, and the time required for shaping is extremely short. Therefore, the resin may not reach the deep part (bottom part) of the concave groove of the shaping roll. Or, even when the resin once enters the deep part due to the pressure at the time of narrow pressure, the shape may return due to residual strain of the resin itself or insufficient cooling, and accurate shaping cannot be performed, and a predetermined uneven shape cannot be obtained There is a problem.

  When the pressure roll is replaced with a rubber roll, the roll surface portion is deformed as compared with the metal roll, so that the narrow pressure distance is increased to about 10 mm. As a result, the time during which the pressure is reduced becomes slightly longer, but such an effect cannot be expected. Further, since the rubber roll is difficult to be mirror-finished like a metal surface, it cannot be said that it is suitable for use as an optical member. On the other hand, metal rolls that exhibit elastic deformation such as rubber rolls (metal elastic rolls) are also sold, but there is also a problem of deformation and sometimes breakage when a high pressure is applied during shaping. As an improvement measure, when the line speed (production speed) is slowed and the pinching time is lengthened, the time from the extrusion die to contact with the shaping roll becomes longer, so the resin temperature decreases and accurate shaping is performed. Will be a hindrance.

  In order to improve these shaping properties, there is a method in which the temperature of the shaping roll is kept high and the viscosity of the resin is lowered as much as possible to suppress the temperature drop of the resin. In this case, since the roll temperature is high when the sheet is peeled from the roll, the sheet is not sufficiently cooled, and the sheet cannot be peeled uniformly from the shaping roll, which causes a problem in appearance. There is also a method of increasing the resin temperature. In this case, problems such as yellowing due to thermal decomposition of the material, an increase in neck-in during contact between the extrusion die and the shaping roll, and unstable sheet thickness control occur.

  According to Patent Document 1, in the extrusion belt molding method, a technique is disclosed in which a sheet obtained by extruding a thermoplastic resin is sandwiched between an endless metal belt and a shaping roll, and the distance is set to 100 mm or more to improve the shaping property. Has been.

The extrusion belt molding method can be expected to improve the formability compared to the extrusion roll method. However, this improvement in formability is, for example, when a two-dimensional lenticular uneven pattern is formed, and it has been difficult to ensure sufficient formability with a three-dimensional concavo-convex pattern.
JP 2006-142682 A

  The present invention intends to solve such problems of the conventional technique by an extrusion molding method, particularly an extrusion belt method. When a resin sheet is produced by an extrusion molding method excellent in productivity, the fine 2 It is an object to make it possible to form a concavo-convex pattern of a dimension or more with good transferability.

  One aspect of the method for producing a resin sheet according to the present invention is a metal endless belt obtained by extruding a thermoplastic resin into a sheet shape and crossing the extruded sheet-shaped resin material on two or more rolls having parallel axes. This is applied to a method for producing a resin sheet in which a concavo-convex pattern is formed on at least one surface of the sheet-like resin material by passing it while being sandwiched between a pressure metal roll and a pressure metal roll, and includes the following procedure. First, a two-dimensional or higher concavo-convex optical pattern is applied to at least one of the metal endless belt and the pressure metal roll. Subsequently, an infrared heater (for example, the heater shown in FIG. 1) having an infrared peak wavelength of about 2 μm or more and 3.8 μm or less immediately before the sheet-like resin material is sandwiched between the metal endless belt and the pressure metal roll. The surface portion of the sheet-like resin material is heated according to 7, 8). The sheet-like resin material is sandwiched between the metal endless belt and the pressure metal roll. The concavo-convex pattern is shaped on the surface portion of the heated sheet-shaped resin material, with the distance between the metal endless belt and the pressure metal roll sandwiching the sheet-shaped resin material being 70 mm or more. Further, before sandwiching the sheet-shaped resin material, the two-dimensional or more uneven optical is formed by an infrared heater having an infrared peak wavelength of about 2 μm or more and 3.8 μm or less or an infrared heater having an infrared peak wavelength of about 1.2 μm. You may heat the said metal endless belt or the said pressurization metal roll to which the pattern was given. In this case, the metal endless belt or the pressure metal roll is preferably provided with a layer made of an inorganic compound on the surface on which the concave-convex optical pattern is applied. As described above, the temperature of the surface portion of the resin sheet and the surface portion of the metal endless belt or pressurized metal roll on which the two-dimensional or higher concavo-convex optical pattern is applied is raised immediately before shaping, and the resin is applied to the concavo-convex pattern in detail. By filling, the transfer rate and molding speed of a fine uneven pattern are improved.

  Moreover, in one aspect of the method for producing a resin sheet according to the present invention, the infrared heater may raise the surface portion of the sheet-shaped resin material in a range of 40 ° C. or more and 60 ° C. or less from the temperature when the extrusion molding is performed. preferable. The pressure metal roll is disposed between the roll core, the concavo-convex pattern member disposed on the surface, the roll core and the concavo-convex pattern, and has a thermal conductivity lower than the thermal conductivity of the concavo-convex pattern member. It is preferable to consist of a heat buffer member. The metal endless belt has a two-dimensional or higher concavo-convex optical pattern, and among the rolls on which the metal endless belt is applied, the roll in which the pressure metal roll sandwiches the sheet-like resin material has a heat insulating material on the surface. It is preferable.

  Furthermore, it is preferable to use a rubber roll coated with rubber as one of the rolls on which the metal endless belt is wound. The infrared heater raises the surface portion of the sheet-shaped resin material after the sheet-shaped resin material is cooled, and the sheet-shaped resin material is formed with an uneven pattern on the heated surface portion.

  Furthermore, in the manufacturing method of the said resin sheet, it is preferable to raise the temperature of the range from the surface of a resin sheet to 20% or less of the thickness of a resin sheet. Moreover, it is preferable that an infrared heater raises the surface part of a sheet-like resin material in 170-200 degreeC with respect to a glass transition temperature.

  Moreover, the one aspect | mode of the optical film concerning this invention is manufactured by the manufacturing method of the resin sheet mentioned above, and the space | interval of an uneven | corrugated pattern will be 1000 micrometers or less.

  Furthermore, one aspect of the resin sheet manufacturing apparatus according to the present invention is a metal obtained by extruding a thermoplastic resin into a sheet shape, and crossing the extruded sheet-shaped resin material on two or more rolls having parallel axes. An apparatus for producing a resin sheet that forms a concavo-convex pattern on at least one surface of the sheet-like resin material by passing it while being pinched between an endless belt and a pressurized metal roll, and has an infrared peak wavelength of about 2 μm or more 3 An infrared heater that heats the surface portion of the sheet-shaped resin material with infrared rays of 8 μm or less and raises the surface temperature of the sheet-shaped resin material that shapes the concavo-convex pattern; and a metal endless belt, a pressure metal roll, At least one of the surfaces is provided with a two-dimensional or higher uneven pattern, and the uneven pattern is formed on the surface portion of the heated sheet-like resin material. Shape the turn. Furthermore, the metal endless belt provided with an infrared heater having an infrared peak wavelength of about 2 μm or more and 3.8 μm or less, or an infrared heater having an infrared peak wavelength of about 1.2 μm, and having a two-dimensional or higher concavo-convex optical pattern Alternatively, the pressure metal roll may be heated. In this case, the metal endless belt or the pressure metal roll is preferably provided with a surface layer of an inorganic compound on the surface on which the concave-convex optical pattern is applied.

  According to one aspect of the method and apparatus for producing a resin sheet according to the present invention, it is possible to improve transferability and molding speed of a fine two-dimensional uneven pattern onto a thin sheet, which has been difficult until now. It becomes.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals, and description thereof is omitted. In the present specification, X to Y indicating a numerical range indicate X or more and Y or less (X and Y are numerical values).

  The method and apparatus for producing a resin sheet according to the present invention includes a sheet-like resin material extruded from an extrusion die, sandwiched between two or more rolls having parallel axes and sandwiched between a pressure metal roll. The present invention is applied to a method and an apparatus using an extrusion shaping method for producing a resin sheet by passing it through. The method and apparatus for producing a resin sheet according to the present invention increases the surface temperature of a sheet-like resin material immediately before an uneven pattern roll that shapes (transfers) an uneven pattern to the resin sheet. Furthermore, the surface temperature of the metal endless belt or the pressure metal roll on which the uneven pattern is applied may be increased. Thereby, the precision and molding speed of transferring a fine uneven pattern are improved, and a good uneven pattern is formed on the resin sheet.

  An example of a sheet extrusion molding apparatus (resin sheet manufacturing apparatus) used in the present invention is shown in FIG. The outline of the sheet extrusion molding apparatus is as follows: an extruder 1, an extrusion die 2, a pressure metal roll 3, a metal endless belt 6 and a rubber roll 4 and a metal roll 5 on which the guide roll (first guide roll) 9, It consists of a guide roll (second guide roll) 10. In addition, the sheet extrusion molding apparatus includes a heater (first heater) 7 and a heater (second heater) 8 as heating means between the extrusion die 2, the pressure metal roll 3 and the metal endless belt 6. About the pressurization metal roll 3, the rubber roll 4, and the metal roll 5, water or oil is stored as a medium inside, and temperature control is possible by circulating them.

  At least one of the pressed metal roll 3 and the metal endless belt 6 is provided with a two-dimensional or higher uneven pattern (appropriately referred to as “uneven optical pattern” or “optical uneven pattern”). Here, the case where an uneven | corrugated pattern is given to both the pressurization metal roll 3 and the metal endless belt 6 is demonstrated. The resin sheet (sheet-shaped resin material) 11 is extruded into a sheet shape by the extrusion die 2 and then passed while being pressed between the pressure metal roll 3 and the metal endless belt 6, so that one side or both sides are formed. Shape the concavo-convex pattern.

  The pressure metal roll 3 used for this invention can be comprised from the metal used with the pressure roll of a general sheet | seat extrusion molding apparatus. Examples of such a metal include iron, a steel material containing iron as a main component, aluminum, an alloy containing aluminum as a main component, and the like. Among these, steel materials can be preferably used in terms of cost and durability. Further, in order to improve the durability of the roll, the surface of the pressure metal roll 3 is generally subjected to hard chrome plating, nickel plating, or the like.

  Moreover, when providing an optical uneven | corrugated pattern member in the pressurization metal roll 3, it is preferable to provide a thermal buffer member between the pressurization metal roll 3 and an optical uneven | corrugated pattern member. Here, the thermal conductivity of the optical concavo-convex pattern member is preferably 30 W / m · K or more, more preferably 40 W / m · K or more, and the thermal conductivity of the thermal buffer member is preferably 0.6 W / m · K. K or less, more preferably 0.5 W / m · K or less. Outside these ranges, cooling of the resin sheet 11 is promoted, which is one of the causes of incomplete filling of the resin into the concavo-convex pattern, and it becomes difficult to form a fine concavo-convex pattern on the surface of the resin sheet 11.

  The thickness of the optical concavo-convex pattern member is preferably in the range of 0.05 to 0.5 mm, more preferably 0.1 to 0.3 mm. If it is 0.05 mm or less, there is a problem in terms of durability, and if it is 0.5 mm or more, there are problems such as high rigidity and inconvenience when attaching to the metal roll 5, and high price. Arise. The thickness of the heat buffer member is preferably in the range of 0.05 to 0.3 mm. More preferably, it is the range of 0.1-0.2 mm. Outside these ranges, it becomes difficult to form a fine uneven pattern on the surface of the resin sheet 11.

  The optical concavo-convex pattern member as described above is not limited as long as it is within the above-described thermal conductivity range. Specifically, the optical concavo-convex pattern member may be composed of materials such as nickel, chromium, stainless steel, zinc, aluminum, brass, and copper. preferable. Also. The heat buffer member is not limited as long as it is within the above-mentioned thermal conductivity range, but polyimide, polyamideimide, polyetherimide, polyethersulfone, polysulfone, polyphenylene sulfide, polyetheretherketone, polyarylate, polytetrafluoroethylene It is preferable to comprise from the material which consists of heat resistant plastics, such as.

  When the pressing metal roll 3 is provided with a concavo-convex pattern, for example, the concavo-convex pattern roll 20 shown in FIG. The uneven pattern roll 20 shown in FIG. 2 includes a roll core body 21, an uneven pattern member (optical uneven pattern member) 22, and a heat buffer member 23. In FIG. 2, the concavo-convex pattern member 22 simply indicates that it has a concavo-convex shape. Specifically, for example, the concavo-convex pattern shown in FIGS. 10 and 13 is applied.

  In the manufacturing method of the uneven pattern roll 20 for sheet extrusion, the following method is used for manufacturing the uneven pattern member 22. For example, the concavo-convex pattern member 22 is prepared by exposing and developing a glass master coated with a photosensitive resin using a photomask or the like to produce a glass master with a concavo-convex pattern, and performing electroless nickel plating on the master. In this method, the concavo-convex pattern member 22 is obtained by further thickening nickel in the electroforming tank. Alternatively, the concave / convex pattern member 22 may be a method of directly cutting the cylindrical concave / convex pattern member 22 from a metal plate such as a brass plate using a precision lathe or the like. The obtained concavo-convex pattern member 22 is bonded and attached to the pressure metal roll 3 and the heat buffer member 23. Specifically, the concavo-convex pattern member 22 is obtained by joining the heat buffer member 23 to an optical concavo-convex pattern non-formation surface using an adhesive (for example, an epoxy-based adhesive or a heat-resistant adhesive). The concave / convex pattern roll 20 is manufactured by attaching to the surface of the pressure metal roll 3 by vacuum adsorption, bonding with an adhesive, fixing with a magnet, mechanical fixing by bolting or the like. can do.

  Specifically, the metal endless belt 6 used in the present invention is preferably made of a material such as nickel, chromium, stainless steel, zinc, aluminum, SUS (stainless steel), carbon steel or a kind of titanium alloy, brass, copper or the like. . A metal endless belt can be manufactured by the same method as the uneven | corrugated pattern member in a pressurization metal roll.

  The metal endless belt 6 is hung on a roll having two or more parallel axes, and sandwiches the pressure metal roll 3 and the sheet-like resin material to form a concavo-convex pattern. Although FIG. 1 shows an example in which the metal endless belt 6 is applied to the rubber roll 4 and the metal roll 5, the present invention is not limited to this. The two or more rolls on which the metal endless belt 6 is multiplied may be only a metal roll, only a rubber roll, or a combination thereof.

  In addition, the rubber roll 4 on which the metal endless belt 6 is hung is a general rubber roll 4 in which the metal roll peripheral surface is coated with heat-resistant rubber or elastic elastomer. When increasing the narrow pressure, for example, a rubber coating thickness of about 5 to 10 mm and a high rubber hardness may be used. Further, the metal roll 5 to be used may be the same as the pressure metal roll 3.

  As the heaters 7 and 8 for heating the resin sheet used in the present invention, an infrared heater having an infrared peak wavelength of about 2 to 3.8 μm is used. By utilizing far infrared rays, the surface portion (in other words, the surface portion to be shaped) can be selectively heated. Infrared heaters that can be used include a carbon heater with an infrared peak wavelength of about 2.0 to 2.5 μm, a medium wavelength infrared heater with an infrared peak wavelength of about 2.6 μm, and a ceramic with an infrared peak wavelength of about 3.8 μm. A heater or a sheathed heater is used. The infrared wavelength band is appropriately selected depending on the type of the thermoplastic resin sheet 11 and the embossing conditions.

  When a near-infrared heater (for example, a halogen heater) having an infrared peak wavelength of about 1.2 μm to 1.6 μm is used as the heaters 7 and 8, the resin sheet 11 tends to be heated to a deep portion. This can also be seen from the spectral light transmittance and absorptance at each wavelength. For reference, the light transmittance of the MS resin sheet at a wavelength of 340 to 2600 nm (manufactured by Hitachi, Ltd., self-recording spectrophotometer U-3400) is shown in FIG. As a characteristic, very high transmittance is shown up to a wavelength of 340 to 2300 nm. In general, the radiation characteristics of the lamp are such that the emitted infrared radiation is distributed on the longer wavelength side than the peak wavelength. Since the near-infrared heater has a peak wavelength of about 1.2 μm to 1.6 nm, the transmittance of the resin is high. Therefore, since the near infrared heater passes light to the inside of the resin, it heats up to the inside of the resin.

  On the other hand, when using a far-infrared heater with a peak wavelength of about 2 to 3.8 μm, the far-infrared tends to have a low transmittance at a wavelength of 2300 nm or more as a characteristic of the resin. It is absorbed relatively near the surface and heated near the surface. Further, in the far infrared heater having a peak wavelength of about 2 to 3.8 μm, the emitted infrared light is also distributed on the long wavelength side.

  For reference, a temperature rising pattern in a resin sheet 11 having a thickness of 0.4 mm when a near infrared heater (quartz heater, peak wavelength about 1.2 μm) and a far infrared heater (seeds heater, peak wavelength about 3.8 μm) are used. Are shown in FIGS. FIG. 4 is a diagram showing an example of a temperature rise pattern (100 V-750 W, L: 200 mm) of a product irradiated with a quartz (near infrared) lamp. FIG. 5 is a diagram showing an example (200 V-1 Kw, L: 680 mm) of a temperature rising pattern of a sheathed (far infrared) heater irradiation product. This shows the resin sheet 11 placed at a position 15 mm away from the heater surface, and the temperature rise rate is observed. When a near-infrared heater is used, the temperature rise rate of the heating surface portion, the counter-heating portion and the intermediate portion (located within 0.2 mm from the heating surface portion) is a temperature difference compared to the far-infrared heater. On the other hand, it can be seen that the far-infrared heater increases the temperature difference. This makes it possible to selectively heat the vicinity of the surface relatively.

  The reason for selectively heating only the vicinity of the surface of the thermoplastic resin sheet 11 is for the following three reasons. One method is to raise the resin temperature by raising the temperature of the extruder 1 and the extrusion die 2. However, this leads to deterioration of the resin, which causes yellowing and causes foreign matter such as contamination due to deterioration inside the extruder 1, and decreases suitability as an optical material. Secondly, even when the problem such as yellowing does not occur by raising the resin temperature, the viscosity of the entire resin sheet 11 is lowered, and the stability between the extrusion die 2 and the shaping roll is a problem. Become. Specifically, the resin sheet 11 vibrates due to slight vibrations generated from the apparatus, and an unstable state such as a change in the contact position with the shaping roll may occur, leading to deterioration of the appearance on the product. Thirdly, there is a problem that it is formability, and a decrease in resin viscosity is advantageous because the resin can easily enter the concave-convex mold, but it is difficult to apply a pressing pressure. Therefore, by increasing the resin temperature only in the vicinity of uneven shaping, the resin viscosity is lowered, so that the resin viscosity of the part that is not shaped (for example, the center part in the sheet thickness direction when double-sided shaping) is not lowered. The pressure is easily transmitted and the shaping property is increased, and the instability phenomenon between the extrusion die 2 and the shaping roll can be suppressed.

One of TiCN, DLC (Diamond Like Carbon), CrCNO, TiAlN, and SiC is provided on the surface of the metal endless belt or the pressed metal roll on which the two-dimensional or higher concavo-convex optical pattern used in the present invention is applied. An inorganic compound layer (inorganic layer) can be provided. Even if the surface of the metal endless belt or the pressure metal roll has a layer made of one of these inorganic compounds partially or entirely, it has a layer made of different inorganic compounds on a plurality of partial surfaces. It may be. By providing this inorganic layer, the amount of absorption at the time of irradiation with an infrared heater is increased, so that it is possible to increase the temperature near the surface in a shorter time than when there is no inorganic layer.
By increasing the temperature in the vicinity of the surface, the filling property when forming the uneven pattern is improved. The method for forming the metal film is not particularly limited, and a physical vapor deposition method such as a vacuum vapor deposition method, a sputtering method, or an ion plating method is employed. The film thickness of the inorganic layer is not particularly limited.

  For heating a metal endless belt or a pressure metal roll having a two-dimensional or higher concavo-convex optical pattern, an infrared heater having an infrared peak wavelength of about 2 μm to 3.8 μm or an infrared peak wavelength of about 1 A 2 μm infrared heater can be used. In the case of using an infrared heater having an infrared peak wavelength of about 1.2 μm, it is preferable to install it at a position where the moldability of the resin sheet for shaping the uneven pattern is not affected, or to consider the irradiation conditions.

  Here, the operation | movement which locally heats the surface of a sheet-like resin material using the infrared rays demonstrated above and performs continuous shaping is demonstrated using a schematic diagram. FIG. 6 shows an example of a partial cross-sectional view of continuous shaping by local surface heating. FIG. 6 shows a state where the resin sheet 11 is sandwiched between the cooling roll 31 and the shaping roll 32. The surface of the resin sheet 11 is heated by the infrared heater 34 and the surface temperature is raised. The resin sheet 11 is pressed against the heated surface portion by applying the pressure F to the shaping roll 32, and the unevenness of the shaping roll 32 is filled with the resin to form an uneven pattern.

  The infrared heater 34 uses infrared rays to melt only the surface of the resin sheet 11 at high speed or to reduce the viscosity at high temperature. Specifically, the predetermined infrared rays described above are condensed by the infrared heater 34 in the region immediately before the shaping roll 32. At this time, if the reflecting plate 35 is arranged, infrared rays can be collected more. The infrared heater 34 heats only the surface portion of the resin sheet 11 in consideration of the infrared absorption characteristics of the resin sheet 11 and the infrared radiation characteristics (surface temperature) of the infrared heater 34. The main body of the resin sheet 11 is heated at room temperature as much as possible, and only the surface portion is heated to about 200 to 300 ° C., for example. It is preferable that the surface portion to be heated is deeper than the depth of the uneven pattern to be shaped, and the depth from the surface to be shaped to 20% or less of the thickness of the resin sheet 11 (the length of the symbol T in FIG. 6). A portion indicated by reference numeral 11 a is a surface portion heated and heated by the infrared heater 34. Moreover, when shaping on both sides of the resin sheet 11, the depth of 20% or less of the resin sheet 11 thickness is heated from each surface.

  It is desired that the introduction of the resin sheet 11 from the heating to the concavo-convex pattern is performed sufficiently quickly so that the temperature of the entire resin sheet 11 is not increased by heat conduction. When the entire temperature of the resin sheet 11 is increased, the resin sheet 11 contracts or deforms, and the original form of the resin sheet 11 cannot be maintained. Therefore, it is necessary to appropriately select the infrared wavelength as described above. Further, it is necessary to finish the shaping before locally heating the surface of the resin sheet 11 to be shaped and conducting heat into the resin sheet.

  Furthermore, in the concavo-convex pattern, it is desirable that a heat insulating material is disposed on the surface opposite to the surface filled with the resin. This is to prevent the resin filled in the uneven pattern from being rapidly cooled. For example, when a concavo-convex pattern is applied to the pressure metal roll 3, it is desirable to apply the concavo-convex pattern roll 20 shown in FIG. In the concavo-convex pattern roll 20, the heat buffer member 23 serves as a heat insulating material, and prevents the resin filled in the concavo-convex pattern member 22 from being rapidly cooled. Further, when the metal endless bell and 6 are provided with a concavo-convex pattern, a heat insulating material such as rubber is disposed around the rubber roll 4 on the shaping side among the two or more rolls on which the metal endless belt 6 is wound. It is desirable. By the heat insulating material, the resin filled in the uneven pattern applied to the metal endless belt is prevented from being rapidly cooled. By disposing the heat insulating material in this way, the surface portion of the resin sheet 11 is maintained at an appropriate temperature until the fine details of the concave and convex pattern member 22 are filled with the resin.

In FIG. 1, the heaters 7 and 8 are provided between the extrusion die 2, the pressure metal roll 3 and the metal endless belt 6, and are applied by at least one of the pressure metal roll 3 and the metal endless belt 6. It is arranged to heat the surface to be shaped. The heaters 7 and 8 are disposed in the vicinity of the pressure metal roll 3 and the metal endless belt 6 (positions closer to the pressure metal roll 3 or the metal endless belt 6 than the extrusion die 2). It is preferable that the surface temperature of the resin sheet 11 rises when the pressure metal roll 3 and the metal endless belt 6 are pressed.
The heated portions of the heaters 7 and 8 are preferably 1.2 times or more the width of the resin sheet 11. This is because it is desired to uniformly heat the entire width of the resin sheet 11 (film width) and raise the temperature. Thereby, it can heat uniformly to the both ends of the resin sheet 11 width.

  The surface temperature of the resin sheet 11 to be raised by the heaters 7 and 8 is preferably raised by 40 to 60 ° C. from the temperature of the resin sheet (sheet-like resin material) extruded from the extrusion die 2. Alternatively, the surface temperature of the resin sheet 11 is desirably increased to an appropriate temperature based on the type of material of the resin sheet 11. For example, the infrared heater raises the surface portion of the sheet-shaped resin material in the range of 170 ° C. or more and 200 ° C. or less with respect to the glass transition temperature. Specific examples of the acrylic resin and the cycloolefin resin are shown in Table 1.

[Table 1] Specific examples of acrylic resins and cycloolefin resins

  Further, in FIG. 1, by providing the heating means of the heaters 7, 8, the discharge temperature of the resin sheet extruded from the extrusion die 2 is relatively lowered in order to increase the surface temperature of the resin sheet 11 immediately before shaping. Is also possible. The shaping is finished before the surface of the resin sheet to be shaped is locally heated to conduct heat inside the resin sheet.

  The molten or softened sheet-shaped resin material processed into a sheet shape inside the extrusion die 2 is pressed in the gap between the pressure metal roll 3 and the metal endless belt 6, and the surface of the pressure metal roll 3 and the metal endless The fine optical concavo-convex pattern on both surfaces of the belt 6 surface is transferred. Thereafter, the sheet passes through the guide roll and is cooled, and at the same time, the warpage and the residual distortion are adjusted to obtain the target optical pattern sheet.

  In addition, in FIG. 1, the case where the uneven | corrugated pattern was given to the pressurization metal roll 3 and the metal endless belt 6 was demonstrated. However, when the uneven | corrugated pattern is given to either one, the resin sheet 11 should just raise only the surface temperature of the side to shape. Specifically, when a fine optical uneven pattern is formed only on the metal endless belt 6 surface, a heater 7 is installed. When a fine optical uneven pattern is formed only on the pressure metal roll 3 surface, a heater 8 is installed. In the case where the optical concavo-convex pattern is formed on both surfaces of the metal endless belt 6 and the pressure metal roll 3, both the heater 7 and the heater 8 are installed. When the concave / convex pattern is applied to either one, the concave / convex pattern member 22 itself is used as the metal endless belt 6, and mounting on the rubber roll 4 and the metal roll 5 is easier than mounting on the pressure metal roll 3. From the metal endless belt 6 side.

  The control of the heat amount of the heater is not particularly limited, for example, an electric part that controls the amount of current such as a slidac.

  The thickness of the resin sheet 11 is preferably in the range of 50 to 400 μm in consideration of the final product. Moreover, the inside of the range of 80-200 micrometers is more preferable.

  As the material of the resin sheet 11, since an optical member is assumed, a highly transparent thermoplastic resin can be used. For example, an acrylic resin, a polycarbonate resin, a polystyrene resin, an MS resin, a cycloolefin resin, an AS resin, Examples thereof include ABS resins, β-pinene resins, and copolymers thereof. Particularly preferred are acrylic resins, cycloolefin resins, and polycarbonate resins. These thermoplastic resins may contain impact modifiers such as acrylic rubber and hydrogenated diene rubber.

  The peeling temperature of the sheet formed with the uneven pattern is preferably around −30 to 0 ° C., more preferably −20 to 0 ° C. of the glass transition temperature. When the temperature is lower than this temperature range, the shape may be destroyed when released from the mold. Moreover, when it is high, the uneven shape may be deformed or out of shape. The resin sheet 11 may be not only a single layer but also a co-extruded multilayer resin sheet. As a method for forming multiple layers, a known method such as a feed block method or a multi-manifold method can be employed.

  Further, when the resin sheet 11 is shaped by being pinched by the pressurizing metal roll 3 and the metal endless belt 6, the shaping accuracy is affected by the distance to be pinched. The clamping distance is a distance in which the resin sheet 11 is substantially clamped by the pressurizing metal roll 3 and the metal endless belt 6. In FIG. 7, the clamping distance is indicated by a symbol D. The clamping distance is preferably 70 mm or more.

  Furthermore, the method and apparatus for producing a resin sheet of the present invention can be applied when the uneven pattern interval is 1000 μm or less, and can form a fine uneven pattern with high accuracy. The interval between the concavo-convex patterns is the interval between adjacent patterns such as the distance between the flat surfaces between the convex portions and the convex portions, or the distance between the flat surfaces between the concave portions and the concave portions.

  By these methods, by heating only the vicinity of the surface of the thermoplastic resin sheet material by heater heating, and by suppressing the rapid temperature drop of the thermoplastic resin sheet in the vicinity of the concavo-convex pattern surface by the heat insulating material or the thermal buffer member, The resin sheet 11 is easily filled into the uneven pattern. For this reason, it becomes possible to further improve the transferability of the fine concavo-convex pattern without increasing the temperature of the cylinder of the extruder 1 and the extrusion die 2. Therefore, the resin sheet 11 having a complicated uneven pattern can be provided by a method having excellent stability.

  Therefore, according to this invention, it becomes possible to provide the resin sheet 11 which has a fine uneven | corrugated pattern on the surface by the sheet | seat extrusion method which has the high freedom degree with respect to the area and thickness of a molded article, and is excellent in productivity. Further, good transferability can be obtained even for a complicated uneven pattern. Therefore, by the method of the present invention, for example, optical members such as a light guide plate, a diffusion sheet, and a lens sheet can be manufactured at low cost.

  1 shows the case where the heaters 7 and 8 are arranged before being pressed between the extrusion die 2 by the pressurized metal roll 3 and the metal endless belt 6, but this is not the only case. Absent. For example, FIG. 8 is a figure which shows the one aspect | mode which heats the surface part of the resin sheet once cooled, and shapes an uneven | corrugated pattern. For example, one surface is processed by the pressure metal roll 3, and after the resin sheet 11 is cooled, the uneven pattern is shaped by being narrowed between the pressure metal roll 3 and the metal endless belt 6. In this case, as shown in FIG. 8, the surface temperature of the resin sheet 11 can be brought to an appropriate temperature state for shaping by heating and heating the surface portion of the resin sheet 11 again with the heater 7. . Thereby, a fine uneven | corrugated pattern can be transcribe | transferred favorably. The heating of the surface portion of the resin sheet 11 by the heater 7 is the same as the above-described conditions (for example, temperature, heating depth, etc.).

  As described above, according to a preferred embodiment of the present invention, a three-dimensional concavo-convex optical system in which a heater for heating a sheet-like thermoplastic resin is installed and hung on a metal roll 5 having parallel axes is provided. By passing the metal endless belt 6 with a pattern between the metal endless belt 6 and a metal roll 5 with a three-dimensional shape, particularly a three-dimensional uneven pattern, a fine uneven pattern with a three-dimensional shape can be accurately applied to one or both sides. The optical sheet to be shaped can be manufactured.

  In particular, by setting the pinching distance to 70 mm or more, the resin can be filled to the deep part of the concave-convex optical pattern groove of the shaping roll, and a concave-convex optical pattern with a shaping ratio of 95% or more can be formed. Thereby, it is possible to produce an optical sheet that exhibits a sufficient front luminance and has a quality comparable to that obtained with other molding methods, particularly those obtained with an ultraviolet curable resin.

  Although the manufacturing method of the thermoplastic resin sheet which has the fine uneven | corrugated pattern of this invention is demonstrated concretely below, this invention is not limited to these Examples. As the uneven pattern, the pattern shown in FIG. 10 was used.

Example 1
Acrylic-styrene copolymer (MS) resin (manufactured by Denka, TP840K) was melt kneaded with a single screw extruder, and the resulting resin melt was extruded from a die at a die outlet temperature of 240 ° C. to form a sheet.

  As shown in FIG. 1, this sheet is provided with heaters 7 and 8 and passed between a pressure metal roll 3 having a diameter of 300 mm and a metal endless belt 6 having a diameter of 255 mm having an optical unevenness pattern. A pattern sheet was prepared. A plurality of convex structures having a cross-sectional shape (conical truncated cone, upper diameter 10 μm, bottom diameter 30 μm, height 19 μm) shown in FIGS. The metal endless belt 6 is provided with a concave pattern opposite to the convex shape of the molded product. The manufacturing conditions are shown in Table 2. The thickness of the resin film was about 300 μm.

  The clamping pressure was 60 kg / cm in terms of linear pressure, and the line speed was constant at 1.5 m / min. The forming rate was expressed as a ratio of the concave depth of the metal endless belt 6 (that is, 19 μm) to the convex height of the truncated cone formed in the molded product, and 95% or more was considered good. The obtained results are shown in Table 2.

[Table 2] Production conditions of resin sheet

Examples 2-4
An optical concavo-convex pattern sheet was produced under the same conditions as in Example 1 except for the temperature of the rubber roll 4 and the temperature of the metal roll 5. Production conditions and results are shown in Table 2.

Comparative Examples 1-3
An optical concavo-convex pattern sheet was produced under the same conditions as in Example 1, Example 3, and Example 4 except that the heater was not heated. Production conditions and results are shown in Table 2.

Comparative Examples 4-5
As shown in FIG. 9, an optical concavo-convex pattern sheet is produced under the same conditions as in Example 2 and Example 4 except that the position of the metal roll 5 on which the metal endless belt 6 is applied is changed and the clamping distance is shortened to 10 mm. did. Production conditions and results are shown in Table 2.

Comparative Example 6
An optical concavo-convex pattern was produced under the same conditions as in Example 1 except that the temperature of the rubber roll 4 and the temperature of the metal roll 5 were changed. The manufacturing conditions are shown in Table 2.

  FIG. 11 is a photograph showing an example of a resin sheet on which a good three-dimensional uneven pattern is formed, and FIG. 12 is a photograph showing an example of a resin sheet on which an incomplete three-dimensional uneven pattern is formed. It is. In FIG. 12, it can be seen that the height of the cone first shape is not sufficient as compared with FIG.

Examples 5 and 6
Acrylic resin (manufactured by Kuraray, Parapet HR-S) was melt kneaded with a single screw extruder, and the resulting resin melt was extruded from a die at a die outlet temperature of 240 ° C. to form a sheet.

  As shown in FIG. 1, this sheet is provided with heaters 7 and 8 and passed between a pressure metal roll 3 having a diameter of 300 mm and a metal endless belt 6 having a diameter of 255 mm having an optical unevenness pattern. A pattern sheet was prepared. A metal endless belt 6 having a surface on which a TiCN layer having a thickness of about 1 μm is formed is used. As for the shape of the molded product, a plurality of convex structures having an irregular pattern shape (pitch 50 μm, height 18 μm) of an isosceles triangle prism shown in FIG. 13 is formed. The metal endless belt 6 is provided with a concave pattern opposite to the convex shape of the molded product. The production conditions are shown in Table 3. The thickness of the resin sheet was about 150 μm.

  The clamping pressure was 60 kg / cm in terms of linear pressure, and the line speed was constant at 2.5 m / min. The thickness of the obtained resin sheet was about 150 μm. The shaping rate was shown by the ratio of the concave depth (that is, 18 μm) of the metal endless belt 6 to the convex height of the truncated cone formed in the molded product. 95% or more was considered good. The obtained results are shown in Table 3.

[Table 3] Manufacturing conditions of resin sheet

Comparative Examples 7 and 8
An optical concavo-convex pattern sheet was produced under the same conditions as in the Examples except that a material having no TiCN layer formed on the surface of the metal endless belt 6 was used. Production conditions and results are shown in Table 3.

It can be seen that the forming rate varies greatly depending on the presence or absence of the TiCN layer on the surface of the metal endless belt.

Example 7
The change in temperature of the concavo-convex optical pattern roll was measured with and without an inorganic layer on the metal endless belt surface.
As a model experiment, a roll with an uneven optical pattern similar to that shown in FIG. 2 as shown in FIG. 14 was heated by a quartz (near infrared) lamp. At that time, the metal roll was rotated at a line speed of 0.5 m / min to 2.5 m / min, and the metal roll surface temperature was measured using a contact-type surface thermometer. The measurement location is 80 mm from the vicinity of quartz lamp irradiation. The roll temperature measurement results are shown in Table 4 and FIG. When a quartz lamp is heated on a surface provided with an inorganic layer (TiCN), the rate of temperature rise tends to be higher than that when no inorganic layer is provided. In FIG. 15, each of 70, 80, and 90 ° C. without the inorganic layer is indicated by a white mark, and each of 70, 80, and 90 ° C. with the inorganic layer is indicated by a solid mark.
[Table 4] Measurement results of Example 7

  In addition, this invention is not limited to embodiment shown above. Within the scope of the present invention, it is possible to change, add, or convert each element of the above-described embodiment to a content that can be easily considered by those skilled in the art.

It is a figure which shows the sheet | seat extrusion molding apparatus (manufacturing apparatus of a resin sheet) used for this invention. It is a figure which shows an example of an uneven | corrugated pattern roll. It is a figure which shows the light transmittance of the resin sheet in wavelength 340-2600nm. It is a figure which shows an example of the temperature rising pattern of a quartz (near infrared rays) lamp irradiation product. It is a figure which shows an example of the temperature rising pattern of seeds (far infrared rays) heater irradiation goods. It is a figure which shows an example of the partial cross section figure of the continuous shaping | molding by surface local heating. It is a figure which shows the pinching distance. It is a figure which shows the one aspect | mode which heats the surface part of the resin sheet once cooled again and shapes an uneven | corrugated pattern. It is a figure (partial drawing) which shows the example of composition which changed the position of the roll which puts an endless metal belt in a sheet extrusion molding device. It is a figure which shows the basic shape of a truncated cone-shaped uneven | corrugated pattern sheet | seat. It is a photograph in case the shaping rate of the frustoconical uneven pattern shown in FIG. 10 is high and good. It is a photograph in case the shaping rate of the uneven | corrugated pattern of truncated cone shape shown in FIG. 10 is low. It is a figure which shows the basic shape of the uneven | corrugated pattern sheet | seat of an isosceles three shape prism. FIG. 10 is a diagram illustrating a configuration of a model experiment of Example 7. 10 is a graph showing measurement results of Example 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 2 Extrusion die 3 Pressurized metal roll 4 Rubber roll 5 Metal roll 6 Metal endless belt 7, 8 Heater 9, 10 Guide roll 11 Resin sheet 11 a Heated surface portion 20 of resin sheet Uneven pattern roll 21 Metal roll 22 Uneven Pattern member 23 Heat buffer material 31 Cooling roll 32 Shaping roll 34 Infrared heater 35 Reflector

Claims (11)

Extruding a thermoplastic resin into a sheet shape, and passing the extruded sheet-shaped resin material while being pressed between a metal endless belt and a pressure metal roll, which are wound on two or more rolls having parallel axes. According to the method for producing a resin sheet, which forms a concavo-convex pattern on at least one side of the sheet-like resin material,
At least one of the metal endless belt and the pressure metal roll is provided with a two-dimensional or higher concavo-convex optical pattern,
Immediately before sandwiching the sheet-shaped resin material between the metal endless belt and the pressure metal roll, the surface portion of the sheet-shaped resin material is removed by an infrared heater having an infrared peak wavelength of about 2 μm to 3.8 μm. Heated,
The sheet-like resin material is sandwiched between the metal endless belt and the pressure metal roll,
The manufacturing method of the resin sheet which shape | molds the said uneven | corrugated pattern in the surface part of the heated said sheet-like resin material as the distance which the said metal endless belt and the said pressurization metal roll clamps the said sheet-like resin material 70 mm or more.   The method for producing a resin sheet according to claim 1, wherein the infrared heater raises the surface portion of the sheet-shaped resin material in a range of 40 ° C. or more and 60 ° C. or less than a temperature when the extrusion molding is performed. A layer made of an inorganic compound made of one of TiCN, DLC, CrCNO, TiAlN, and SiC is provided on the surface of the metal endless belt or the pressure roll, which has a two-dimensional or higher concavo-convex optical pattern. And
Before sandwiching the sheet-shaped resin material, the metal endless belt or the additional belt is heated by an infrared heater having an infrared peak wavelength of about 2 μm to 3.8 μm, or an infrared heater having an infrared peak wavelength of about 1.2 μm. The method for producing a resin sheet according to claim 1 or 2, wherein the temperature of the surface portion of the pressure roll is raised.   The pressure metal roll is disposed between a roll core, a concavo-convex pattern member disposed on the surface, and the roll core and the concavo-convex pattern, and has a thermal conductivity lower than the thermal conductivity of the concavo-convex pattern member. The method for producing a resin sheet according to any one of claims 1 to 3, wherein the method comprises a thermal buffer member having a rate. The metal endless belt has a two-dimensional or higher concavo-convex optical pattern. Among the rolls on which the metal endless belt is applied, the roll in which the pressure metal roll sandwiches the sheet-like resin material has a heat insulating material on the surface. The method for producing a resin sheet according to claim 1, wherein the resin sheet is arranged.   The method for producing a resin sheet according to any one of claims 1 to 5, wherein a rubber roll covered with rubber is used as one of the rolls on which the metal endless belt is wound. The infrared heater raises the surface portion of the sheet-shaped resin material after the sheet-shaped resin material is cooled,
The method for producing a resin sheet according to any one of claims 1 to 6, wherein the sheet-shaped resin material has the uneven pattern formed on a heated surface portion.   The method for producing a resin sheet according to any one of claims 1 to 7, wherein the temperature in the range from the surface of the resin sheet to 20% or less of the thickness of the resin sheet is increased.   The said infrared heater raises the surface part of the said sheet-like resin material in the range of 170 degreeC or more and 200 degrees C or less with respect to a glass transition temperature, It is any one of Claims 1 thru | or 8 characterized by the above-mentioned. Manufacturing method of resin sheet.   An optical film produced by the method for producing an optical film according to any one of claims 1 to 9, wherein an interval between the concavo-convex patterns is 1000 µm or less. Extruding a thermoplastic resin into a sheet shape, and passing the extruded sheet-shaped resin material while being pressed between a metal endless belt and a pressure metal roll, which are wound on two or more rolls having parallel axes. According to the present invention, a resin sheet manufacturing apparatus for shaping a concavo-convex pattern on at least one side of the sheet-shaped resin material,
An infrared heater that heats the surface portion of the sheet-like resin material with infrared rays having an infrared peak wavelength of about 2 μm or more and 3.8 μm or less, and raises the surface temperature of the sheet-like resin material that shapes the uneven pattern;
At least one surface of the metal endless belt and the pressure metal roll is provided with a two-dimensional or higher uneven pattern,
The apparatus for producing a resin sheet, wherein the uneven pattern forms an uneven pattern on a surface portion of the heated sheet-shaped resin material.