JP5560800B2 - Method for producing fine shape transfer film and fine shape transfer film - Google Patents

Description

  The present invention relates to a film having a fine shape transferred to the surface and a method for producing the same.

  2. Description of the Related Art Conventionally, a method for producing an optical film used for an embossed sheet or a liquid crystal display having a high design property by transferring a fine shape onto a film surface is known.

  Patent Document 1 is a method for producing a sheet, in which a continuous sheet made of a thermoplastic resin is sandwiched between a heated uneven roller and a nip roller to continuously transfer and form a fine uneven surface on the sheet surface. A method is disclosed in which when a sheet passes through a portion, a support made of a plastic endless belt is laminated and run parallel to prevent the sheet from drooping down when it is expanded in the direction of travel by heat.

  However, in the present technology, no treatment such as adhesion or adhesion is performed between the support and the film. Therefore, the support has rigidity with respect to wrinkles generated by thermal expansion in the width direction when the film is thinned. Even if it cannot be avoided. Further, when the deformation amount of the rubber on the surface of the nip roller of the pressing portion exceeds the thickness of the thinned film, there is a problem that the nip rollers come into contact with each other and the pressure is reduced. In the same field where further miniaturization advances, a high pressure is required to fill the resin with the mold, and the contact between the mold roller and the nip roller becomes a big problem.

  On the other hand, a technique such as Patent Document 2 is disclosed for maintaining the form of a film during thermal processing. In this document, when a polyimide film and a copper foil are heat-sealed at a high temperature of 200 ° C. or higher, a process of laminating and peeling a protective film is included in order to avoid wrinkles due to thermal expansion and thermal shrinkage. In the manufacturing process disclosed in this document, the fine processing using a heating process is not the purpose, but the pressing process is performed between metal rollers, and there is a problem such as a pressure drop due to the deformation of the nip roller when the film is thinned. I don't have it. Therefore, since the thickness of the protective film is determined only for the purpose of avoiding thermal wrinkles, the process of laminating and peeling the protective film described in Patent Document 2 as a means for avoiding the above pressure drop was unsuitable. .

  As described above, conventionally, there has been no good means for achieving both heat wrinkles and securing of pressure necessary for fine shape processing when transferring a heat fine shape which is becoming thinner to a film.

Japanese Patent No. 4232608 JP 2002-326280 A

  The object of the present invention is to solve the above-mentioned problems of the prior art, and even if the film is thinned, wrinkles and pressure drop due to heating do not occur, and the fine shape has a high filling rate and a uniform processed surface in the width direction and longitudinal direction. It is in providing the manufacturing method of the fine shape transfer film which has these, and the fine shape transfer film obtained by this.

In order to achieve the above object, the present invention has the following configuration. That is,
(I) The surface of a thermoplastic film having a thickness of 100 μm or less is heated to a glass transition point or more, and the surface is brought into contact with a mold roller having a fine shape provided on the surface. Production of a fine shape transfer film satisfying the following (1) to (3) in a fine shape transfer film production method in which the film is sandwiched between a roller and a nip roller opposed to the fine film, and the fine shape is transferred to the film and cooled. Method,
(1) The surface of at least one of the mold roller or nip roller is coated with resin or elastomer,
(2) The thermoplastic film is laminated with a protective film layer,
(3) The total thickness of the laminate of the thermoplastic film and the protective film is not less than the amount of deformation in the thickness direction of the resin layer or elastomer layer on the roller surface.
(4) The protective film is peeled off immediately before cooling the thermoplastic film.
( II ) The method for producing a fine shape transfer film according to (I) , wherein the rubber hardness of the resin layer or elastomer layer on the roller surface is 70 to 97 ° according to ASTM D2240: 2005 (Shore D) standard,
( III ) The peeling force between the protective film layer and the thermoplastic film when peeling the protective film immediately before cooling the thermoplastic film is 0.3 mN / mm or more and 35 mN / mm or less ( A method for producing a fine shape transfer film according to (I) or (II) ,
( IV ) The method for producing a fine shape transfer film according to any one of (I) to ( III ), which satisfies the following formula (a):

Here, the linear expansion coefficient of the protective film is α, the temperature difference between the molding temperature and the film introduction temperature is ΔT, the thickness of the protective film is t, and the width of the thermoplastic film is b.
(VI) The thickness of the film is 100 μm or less, the fine shape is continuously formed in the length direction over 500 m or more on the surface, and the variation in the height of the fine shape in the width direction is 5% or less. A fine shape transfer film in which the representative pitch of the fine shape is 0.5 mm or less, and the film material is a thermoplastic resin,
(VII) The fine shape transfer film according to (VI), wherein the fine shape is a prism,
It is.

(Definition of terms)
In the present invention, “fine shape” means a three-dimensional geometric shape having a pitch or depth of 500 μm or less, or a random uneven shape that can be observed through a microscope, and examples thereof include a prism shape and a satin shape. Is mentioned.

  In the present invention, the “mold” refers to a structure having the fine shape on the surface and having rigidity and strength capable of withstanding pressure in the thickness direction. In particular, the “mold roller” refers to the fine shape on the surface. It refers to a rotating body (roller) that has been applied, or a roller that covers a sleeve or belt having a fine shape.

  In the present invention, the “nip roller” is a rotating body that faces the mold roller in the radial direction or a direction close to the radial direction and clamps the film.

  In the present invention, the “thermoplastic film” is a band-like material obtained by molding a thermoplastic resin once melted into a sheet shape and solidifying, and has a large width with respect to the thickness and a length with respect to the width. Say something that can be rolled up.

  In the present invention, the surface of the roller is coated with resin or elastomer. This is because, when the film is sandwiched between the nip roller and the mold roller, a contact width is developed in the sandwiched portion by elastic deformation of the roller surface. It is. The roller surface is coated with a resin or elastomer having a small elastic coefficient. Here, the elastomer means a resin or rubber having rubber-like elasticity.

  In the present invention, “lamination” includes a case where adhesion is performed using an adhesive lamination or an adhesive, and the like. Here, “adhesive lamination” refers to a state in which two objects can maintain contact by self-adhesive force without using external force without using an adhesive such as glue. In the present invention, “adhesion” refers to a state in which two objects are similarly maintained in contact with each other regardless of external force using an adhesive such as glue.

  In the present invention, “the amount of deformation in the thickness direction of the resin layer or elastomer layer on the roller surface” means that the resin layer or elastomer layer on the roller surface in the thickness direction is caused by the pressing force acting between the mold roller and the nip roller. The amount of compression deformation.

  In the present invention, the “peeling force between the protective film and the thermoplastic film” refers to a force in the thickness direction when the two films laminated or adhered as described above are peeled off.

  In the present invention, the “molding temperature” refers to the surface temperature of the mold roller or the surface of the thermoplastic film where the mold roller and the thermoplastic film start to contact.

  In the present invention, the left side of Equation 2 represents the amount of thermal expansion during molding, and the right side represents the buckling limit deformation obtained from Euler's buckling theory and experiment. Therefore, Formula 2 shows a limit value at which wrinkles due to heat do not occur.

  In the present invention, “a fine shape is continuously formed on the surface over a length of 500 m or more” means a margin (a portion where the fine shape is not transferred) or a portion where the fine shape is not transferred due to the overlap. The state which does not extend over 500m in the direction is shown.

  In the present invention, the “representative pitch” refers to a pitch when this shape is repeated when the fine shape is a geometric shape. On the other hand, when the fine shape is a random shape such as satin, it is represented by an average value of the distances between the ten convex portions.

  In the present invention, the “prism” refers to a fine shape in which triangular prism shapes that transmit and refract light are aligned in the width direction or the length direction.

  According to the present invention, as described below, it is possible to obtain a method for continuously producing a thermoplastic film excellent in fine shape transferability.

It is a schematic side view of the manufacturing method of the fine shape transfer film concerning one Embodiment of this invention. It is a schematic side view of the metal mold | die roller 4 concerning another one Embodiment of this invention. It is an example of the fine-shaped cross section concerning one Embodiment of this invention. It is an example of the fine shape cross section concerning another one Embodiment of this invention. It is an example of the fine shape cross section concerning another one Embodiment of this invention. It is a schematic side view of the roller concerning one embodiment for showing the amount of deformation of the resin layer or elastomer layer of the roller surface of the present invention. It is the schematic sectional drawing which showed the relationship between the deformation | transformation amount of the roller surface concerning one Embodiment of this invention, and a laminated body thickness. It is a schematic side view of the manufacturing method of the uneven | corrugated sheet | seat concerning embodiment of a prior art. It is a schematic side view of the peeling force measuring method of a thermoplastic film and a protective film.

  Hereinafter, an example of the best embodiment of the present invention will be described with reference to the drawings, taking as an example the case of applying to a method for producing a fine shape transfer film when a prism shape is transferred and molded onto the surface.

FIG. 1 is a schematic side view of a method for producing a fine shape transfer film according to an embodiment of the present invention. In FIG. 1, the thermoplastic film 2 is continuously supplied from an unwinding roll 10. The unwinding roll 10 is pre-wound on an unwinding roll core 13, and the core 13 is rotatably supported by a support means such as a holder and a chuck, and a motor, a brake, It is connected to driving means such as a clutch and is driven to rotate. Moreover, in order to supply this film 2 continuously, you may arrange | position not only the form of the unwinding roll 10, but the film formation process etc. which melt-extrude a thermoplastic polymer from a nozzle | cap | die.
Here, the material constituting the thermoplastic film 2 is at least one kind of heat selected from the group consisting of polyester resin, polyolefin resin, polycarbonate resin, polystyrene resin, acrylic resin, and mixtures and / or copolymers thereof. A plastic resin is exemplified. Among them, polyester resins, polystyrene resins, polycarbonate resins, and cyclic polyolefin resins are easy to copolymerize, and can be adjusted for physical properties according to various applications, and can be easily molded, so these resins are the main components. It is preferable. Here, the “main component” means that 50% by mass or more is contained per component constituting the thermoplastic film.

  The polyester preferably used in the present invention is composed of an acid component such as aromatic dicarboxylic acid, alicyclic dicarboxylic acid or aliphatic dicarboxylic acid and a diol component. Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-diphenyldicarboxylic acid. Acids, 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid and the like can be used, and among them, terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid are preferable. As the alicyclic dicarboxylic acid component, for example, cyclohexane dicarboxylic acid or the like can be used. As the aliphatic dicarboxylic acid component, for example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be used. These acid components may be used alone or in combination of two or more.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2′-bis (4 '-Β-hydroxyethoxyphenyl) propane and the like can be used. Among them, ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol and the like can be used, and particularly preferably. , Use ethylene glycol, etc. be able to. These diol components may be used alone or in combination of two or more.

  The polyolefin preferably used in the present invention is an aliphatic polyolefin resin such as polyethylene, polypropylene, polyisobutylene, polybutene, and polymethylpentene, and a cyclic polyolefin resin obtained by ring-opening metathesis polymerization of a norbornene derivative. And a cyclic polyolefin copolymer resin obtained by copolymerizing a norbornene derivative and an α-olefin such as ethylene, propylene, butene, and pentene.

  Examples of the acrylic resin preferably used in the present invention include polymethyl methacrylate.

  In addition, various additives can be added to the molding layer resin and the support layer resin constituting the thermoplastic film 2 of the present invention within a range where the effects of the present invention are not lost. Examples of additives that can be added and blended include, for example, organic fine particles, inorganic fine particles, dispersants, dyes, fluorescent brighteners, antioxidants, weathering agents, antistatic agents, polymerization inhibitors, mold release agents, Examples include thickeners, pH adjusters, nucleating agents, and salts. Examples include crystal nucleating agents and salts. When a crystal nucleating agent is added to the molding layer resin, crystallization during thermoforming of the molding layer resin is promoted by lowering the crystallization free energy, and this crystallization suppresses the molecular motion of the amorphous part. Further, it is preferable because the heat resistance of the shape imparted by thermoforming is improved by the decrease in molecular mobility due to crystallization. For example, as the crystal nucleating agent, weak acid salts such as alkali metal compounds, alkaline earth metal compounds, zinc compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, germanium compounds, etc. are preferable, among which sodium acetate, sodium behenate, Addition of magnesium acetate, sodium montanate, alumina, zirconia, mica, clay, talc or the like as a crystal nucleating agent during the polymerization of the resin is particularly preferred from the viewpoint of reducing the crystallization free energy of the molding layer resin.

  In the thermoplastic film 2 of the present invention, particularly in the surface layer to which the fine shape is transferred, the glass transition point is 80 ° C. or higher, more preferably 85 ° C. or higher, further preferably 100 ° C. or higher, most preferably 120 to 150 ° C. is there. In this case, a molded sheet after molding is preferable because of excellent heat resistance. When the glass transition point is less than 80 ° C., the heat resistance of the molded sheet becomes low, and it becomes difficult to use it for applications requiring heat resistance.

  Here, the glass transition point Tg was determined by the following procedure. Using DSC as a DSC robot “DSC220” manufactured by Seiko Electronics Industry Co., Ltd. and as a data analysis device using the company's disk station “SSC / 5200”, 5 mg of the composition or film sample was filled into an aluminum tray, and this sample was used. It heated from normal temperature to 300 degreeC with the temperature increase rate of 20 degree-C / min, was melted for 5 minutes, and was then rapidly cooled with liquid nitrogen. In this process, the glass transition temperature is measured.

  The thermoplastic film used in the present invention has a thickness of 100 μm or less. The fine shape transfer film for optical uses and industrial uses used for displays and the like is preferable because the entire device can be made thin and small by reducing the thickness of various functional films including the fine shape film of the present invention. The thickness is 100 μm or less. Furthermore, by setting the film thickness to 60 μm or less, it can be preferably applied to reduce the thickness and size of the industrial equipment.

Here, the thickness of the film to which the fine shape has been transferred is preferably represented by a weight average thickness t (m). This is a suitable measurement method when it is difficult to measure the thickness itself when a fine shape is transferred. Measure the weight W (g) of the film cut to a predetermined length L (m) and width b (m), and assume the film density ρ (g / m ^ 3) as a weight average. Thickness t = W / (bLρ).
In FIG. 1, the thermoplastic film 2 is preliminarily laminated with a protective film 3 to form a laminate 1. Here, with respect to the method of adhesive lamination of the thermoplastic film 2 and the protective film 3, the protective film 3 is made of a self-adhesive film made of low-density polyethylene having a small surface roughness, so that no glue is used. It can affix on the said thermoplastic film 2. As a method of attaching the protective film 3 to the thermoplastic film 2, a method of continuously laminating with a nip roller or the like is preferable. Moreover, as a means to carry out adhesion lamination of the thermoplastic film 2 and the protective film 3, you may achieve by laminating | stacking the thermoplastic film 2 and the protective film 3 in a molten state, and coextruding from a nozzle | cap | die.

  Moreover, when forming the laminated body 1 which consists of the thermoplastic film 2 and the protective film 3 previously, you may adhere | attach. As an adhesion method, an adhesive such as glue may be applied to any surface between the thermoplastic film 2 and the protective film 3 and then laminated with a nip roller. When the protective film 3 is laminated in a molten state and co-extruded from the die, an adhesive component such as glue may be contained on the protective film side for adhesion. At this time, in order to prevent contamination of the guide roll and the like, it is preferable to use a component that does not cause the adhesive such as glue to fall off, and it is more preferable to apply the adhesive to the protective film side.

  Moreover, as long as the thermoplastic film 2 and the protective film 3 are not heated, the laminated body 1 may be formed by adhesive lamination or bonding at any timing.

  The thermoplastic film 2 constituting the laminate 1 is heated to a temperature equal to or higher than the glass transition point by the film preheating means 6 or the mold roller 4. The film preheating means 6 is preferably a lamp heater, ceramic heater, hot air nozzle or the like. Also, the mold roller 4 is preferably heated from the surface or inside by the same heating means.

  Further, for the purpose of making the pressing force uniform and suppressing vibrations, it is necessary that at least one of the surfaces of the mold roller 4 or the nip roller 5 is coated with a resin or an elastomer. is there. For example, when the mold roller 4 is coated with resin or elastomer, a finely shaped layer is separately provided as the outermost layer. At this time, the fine shape layer is preferably made of a strong material, for example, a metal such as nickel, steel, stainless steel, or copper.

Furthermore, in order to prevent breakage of the finely shaped portion on the surface of the mold roller, the surface of only the nip roller 5 is preferably a resin layer or an elastomer layer. The purpose of the resin layer or the elastomer layer is to make the pressing force uniform and to secure the pressing force for a predetermined time when transferring the fine shape of the mold by softening the resin. This is because the pressing time can be secured by the deformation of the layer. Here, the resin or elastomer used on the roller surface is preferably a material having a lower elastic coefficient than that of metal or the like and exhibiting deformation as shown in FIG. 6 when pressed. When rubber is used as the elastomer, for example, silicone rubber, EPDM, neoprene, CSM, urethane rubber, NBR, ebonite, or the like can be used. When seeking higher elastic modulus and hardness, use a special prescription for the rubber from the rubber manufacturers as a resin for calender rollers, or use a hard pressure resistant resin (eg polyester resin) with improved toughness. Can do. For these elastomers and resins, those having a prescription excellent in pressure resistance and heat resistance can be preferably applied.
FIG. 6 shows only the nip roller 5 taken out when the nip roller 5 is pressed against the mold roller 4 and the laminated body 1. At this time, the surface of the nip roller 5 is covered with a resin layer or an elastomer layer typified by rubber, and this rubber layer is deformed as shown in the figure by Hertzian contact pressure p generated by the pressing force. At this time, a deformation amount δ is generated in the thickness direction of the rubber, and accordingly, the laminate 1 comes into contact with the contact width B. Multiplying the contact width by the traveling speed of the film is the contact time, which is the pressing time described above.

  FIG. 7 shows the form of the thermoplastic film 2, the protective film 3, and the rubber deformation amount δ of the present invention. When a thin thermoplastic film having a thickness of 100 μm or less as in the present invention is processed by heating and fine shape processing, if the rubber deformation amount δ exceeds the film thickness, the rubber contacts the opposing roller at a portion other than the film in the figure. Therefore, the pressure p required for molding is not applied to the thermoplastic film, and there is a possibility that the fine shape transfer processing cannot be performed with high accuracy. Therefore, as shown in the figure, the total thickness t2 of the laminate of the thermoplastic film 2 and the protective film 3 is equal to or greater than the deformation amount in the thickness direction of the resin layer or the elastomer layer.

  As the resin layer or the elastomer layer used here, a rubber or a thermoplastic elastomer can be selected, and a resin having a high pressure resistance such as that used in a calendar process can be preferably used. In order to realize the deformation amount δ, an elastic coefficient is important as a property of rubber or thermoplastic elastomer. However, the relationship between the force of rubber or elastomer and the amount of deformation is often non-linear, and it is difficult to uniquely determine the elastic coefficient. Therefore, in order to control the deformation amount, it is preferable that the elastic modulus is expressed by rubber hardness, and more preferably, the hardness is 70 ° to 97 ° according to ASTM D2240: 2005 (Shore D) standard. preferable. This is because when the hardness is less than 70 °, the deformation amount δ of FIG. 6 becomes too large as described above, and may exceed the total thickness t2 of the thermoplastic film 2 and the protective film 3 shown in FIG. There is a risk that the pressure p necessary for transferring the fine shape cannot be secured. On the other hand, when the hardness exceeds 97 °, the deformation amount δ of the layer becomes too small, the contact width B with the laminate 1 becomes small, and the pressing time described above may not be ensured. Therefore, in this invention, it discovered that the pressure required in order to transcribe | transfer a fine shape was ensured also in the thermoplastic film 2 reduced in thickness by prescribing | regulating the hardness of this layer and the thickness of the said laminated body.

  Furthermore, various coatings or the like for improving heat resistance, slidability and releasability may be applied thinly on the outermost layer of the resin layer or elastomer layer.

  The mold roller 4 and the nip roller 5 are rotatably supported by a rolling bearing or the like. Preferably, either the mold roller 4 or the nip roller 5 may be rotationally driven while controlling the speed or the like by means such as a motor. The speed is preferably 1 m / min to 100 m / min, and the productivity can be increased while transferring the fine shape with high accuracy. Further, 5 m / min to 50 m / min is preferable for the above request. .

  As shown in FIG. 1, the nip roller 5 has a bearing connected to a pressing means 7 such as a cylinder, and presses the laminated body 1 with the mold roller 4. At this time, pressure only has to be applied in the thickness direction of the laminated body 1, so that pressing means may be provided on the mold roller 4 side with respect to the nip roller 5 to sandwich the laminated body 1.

  The core material of the mold roller 4 and the nip roller 5 is preferably one having rigidity and strength with respect to the pressing force, and for example, steel, fiber reinforced resin, ceramics, aluminum alloy, and the like are conceivable. With respect to the method of providing a fine shape on the surface of the mold roller 4, the core material may be directly processed by cutting or lasering, or the core material may be plated and finely processed. Further, the roller 4 may be coated by applying a fine processing to a thin film sleeve manufactured by electrocasting or rolling, or a cylinder. Alternatively, a fine shape may be processed after the sleeve or cylinder is covered with the roller 4. In addition, as shown in FIG. 2, the idler roller 16 may be used to configure the mold roller 4 with the sleeve as the endless belt 17.

  Examples of the fine shape include a prism as shown in FIG. 3, a geometric shape used for an optical member such as a lenticular as shown in FIG. 4, and a random shape such as a satin as shown in FIG.

  Here, in order to obtain the representative pitch P having a random shape as shown in FIG. 5, it may be expressed by the average value of the distances between the ten convex portions as described above. The same applies to the representative depth D. Even if the total number of concavo-convex portions is less than 10 points, the average value may be obtained with this maximum number.

  Next, it is preferable to cool the thermoplastic film 2 after transferring the fine shape by heating and pressing. This can improve the fine shape transfer accuracy by cooling and solidifying the polymer filled with the pressure to the fine shape by heating and flowing to maintain the shape. Although the cooling means may be provided on the mold side, it is preferable that the thermoplastic film 2 and the protective film 3 are peeled off before cooling as shown in FIG. The film cooling means 8 in FIG. 1 cools the polymer from the back side of the film, and sprays heat from the film surface, such as spraying a coolant such as water, applying cold air, or utilizing vaporization heat by negative pressure vacuum. Anything that can be taken away.

  More preferably, the peel force between the thermoplastic film 2 and the protective film 3 is preferably 0.3 mN or more and 35 mN or less per 1 mm width. When the peeling force is 0.3 mN or less, when the film is subjected to thermal stress due to preheating or thermal expansion or contraction due to radiant heat from the mold roller 4, the protective film 3 holds the shape of the film and avoids wrinkles. It becomes difficult to do. Moreover, when peeling force is 35 mN or more, when peeling the thermoplastic film 2 and the protective film 3 just before the said cooling process, tension | tensile_strength fluctuation | variation, winding, etc. generate | occur | produced, and the continuous fine shape transfer film of stable Manufacturing can be difficult. About the measuring method of peeling force, the force at this time is measured, developing the thermoplastic film 2 and the protective film 3 in a 180 degree direction like FIG. For example, the force can be measured by using a commercially available tensile tester.

  Here, as a protective film, it is preferable that the longitudinal elastic modulus of the width direction is 3 GPa or more. When the laminated body 1 is formed by laminating the thermoplastic film 2 and the protective film 3, it becomes difficult to wrinkle and can be laminated uniformly.

  When the film thermally expands or contracts in the molding temperature range, if the thermoplastic film 2 is subjected to thermal stress, if the film exceeds the buckling stress of the film 2, the film buckles and wrinkles. Whether or not the film 2 or the laminate 1 is wrinkled can be predicted by introducing a deformation amount such as thermal expansion as a boundary condition by numerical calculation such as a finite element method. I found it to be judged by a simple calculation formula.

Formula 2 is Euler's buckling formula known in material mechanics, and P _cr indicates a buckling limit load. Here, E is the longitudinal elastic modulus in the width direction of the film, I is the second moment of section, and b is the film width. n is a natural number determined by the terminal condition, and an experiment is necessary under the conditions of the present invention in which the restraint portion is determined by the downstream pressing portion. The inventor has measured the condition that the film is wrinkled by heating, and found by experiment that n = 36. When the length of the heat affected zone of the film is H and the value measured in the length direction of the film is H, the cross-sectional secondary moment is as shown in Equation 3.

  If the thermal expansion coefficient of the protective film 3 is α and the temperature difference between the molding temperature and the film introduction temperature is ΔT, the load generated by the thermal expansion or contraction of the film is the left side of Equation 4. On the other hand, the right side of Expression 5 is an expression obtained by substituting the buckling load shown in Expression 2 with the moment of inertia of the cross section shown in Expression 3, and the fact that the inequality of Expression 4 holds is a condition that does not cause wrinkles. The inventors have found. If the parameters existing on both sides are deleted from Expression 4, Expression 4 is obtained. Here, E and H described above can be deleted from this mathematical formula, and the heat-affected zone H of the film is not necessarily measured. Further, when the thermal expansion coefficient α of the thermoplastic film 2 and the protective film 3 is close, the longitudinal elastic modulus E may not necessarily have to be taken into consideration as expressed by Equation 4, but the protective film 3 is in contrast to the thermoplastic film. When the thermal expansion is small, it is preferable that the longitudinal elastic modulus E of the protective film 3 is high. Therefore, apart from the above reasons, it can be said that the longitudinal elastic modulus E of the protective film 3 is preferably 3 GPa or more.

  The film having the fine shape transferred in the production process of the present invention is wound up as a laminate 1, or preferably after the protective film 3 is peeled off just before cooling as shown in FIG. 1, and the thermoplastic film 2 is used as the fine shape transfer film roll 11. Winding, on the other hand, the protective film 3 may be wound as the protective film roll 12. At this time, each film roll is preferably wound while applying tension on the cores 14 and 15. The winding cores 14 and 15 are supported by a rotation support unit, and are connected to a rotation drive unit such as a motor as necessary, and take up the film while controlling tension and speed. The tension controlled here is preferably about 5 N / m to 500 N / m, more preferably 10 N / m to 20 N / m.

  Here, according to the present invention, even in the thin thermoplastic film 2 having a thickness of 100 μm or less, the pressure necessary for fine shape transfer can be applied while ensuring the necessary pressing time. The fine shape can be continuously transferred to the surface of the film 2 over 500 m or more. In particular, even when the film is heated to a temperature higher than the glass transition point, pressure necessary to transfer a fine shape can be applied while avoiding wrinkles. Even in the shape, it is possible to obtain a very high-quality film over 500 m with a height variation of 5% or less. Here, the mold roller 4 may be provided with a seam or a margin. However, by forming the fine shape of the die roller 4 in the circumferential direction without a margin, a continuous fine shape having no margin over 500 m or more can be obtained. Can do.

  Furthermore, it is particularly suitable for a fine shape having a high aspect ratio such as a prism, and a high quality film can be obtained continuously at low cost as an optical film.

The result of manufacturing the fine shape transfer film using the above method for producing a fine shape transfer film will be described.

[Example 1]
In the manufacturing method of the fine shape transfer film in FIG. 1, the protective film 3 was passed through a cooling means without being peeled, and wound up as it was. As the thermoplastic film 2, a biaxially stretched polyester film having a thickness of 50 μm, a width of 500 mm, and a copolymer of naphthalenedicarboxylic acid at a ratio of 5 to 50 mol% was used.

  The film was conveyed at a speed of 30 m / min by rotationally driving a nip roller 5 connected to a motor.

  The thermoplastic film 2 is laminated in advance as a laminate 1 with a protective film 3 in which an adhesive made of an isocyanate type acrylic resin is applied to a polyester film (trade name Lumirror, manufactured by Toray Industries, Inc.) having a thickness of 188 μm. The unwinding roll 10 is configured. The roll 10 was previously wound around a winding core 13, and the winding core 13 was driven and supported by a rotation support means, and the unwinding tension was controlled to 100 N / m. The winding length of the unwinding roll was 1000 m.

  As the winding core 13 and the winding core 14, a paper cylinder was used, which had an inner diameter of 152 mm, an outer diameter of 172 mm, and a length of 600 mm.

As the mold roller 4, a cylindrical core material made of carbon steel plated with nickel and a prism 18 as shown in FIG. 3 cut is used. The roller 4 has an outer diameter of 300 mm, a shaft that is coaxially engaged with both ends of a core member having a width of 600 mm, and the shaft is rotatably supported by a bearing. Further, considering the processing efficiency, the prism 18 has a pitch of 40 μm and a depth of 20 μm. Unlike the schematic diagram of FIG. 1, the prism 18 is processed into a spiral shape with a pitch of 20 μm in the roll circumferential direction.
The bearing of the nip roller 4 was attached so that it could be pressed against the mold roller 4 by the hydraulic cylinder 7, and the laminated body 1 was continuously clamped.

  In the nip roller 4, the surface of a cylindrical core made of carbon steel having an outer diameter of 280 mm was coated with a 10 mm thick pressure-resistant special polyester resin (Ellaglass ZE, manufactured by Kinyo Co., Ltd.). The resin used has a hardness of 96 ° according to ASTM-D standard (Shore D) and a pressure resistance of 1000 kN / m.

  Here, the pressure was applied from the hydraulic cylinder to the nip roller 4 as 175 kN on one side and 700 kN / m as a linear pressure per meter. At this time, the resin layer on the surface of the nip roller 4 was deformed by δ = 200 μm as shown in FIG. 6, and as a result, it was confirmed that the contact width B with the film was 5 mm. This confirmed that the deformation amount δ was smaller than the thickness t2 of the laminate 1.

[Example 2]
Another example of one embodiment of the present invention will be described. In this embodiment, in order to see the effect of peeling off the protective film immediately before cooling, the protective film 3 is peeled off from the thermoplastic film 2 before cooling as shown in FIG. The protective film 2 was manufactured so that the peeling force at this time was 34 mmN / mm.

[Example 3]
Another example of one embodiment of the present invention will be described. In this example, in order to see the influence of the peeling force of the protective film 3, as shown in FIG. 1, the protective film 3 is peeled off from the thermoplastic film 2 before cooling, and the peeling force at this time is 7 mmN / mm. A protective film 2 was produced.

[Comparative Example 1]
The embodiment of the prior art is based on Patent Document 1, and the manufacturing method as shown in FIG. 8, the thermoplastic film 2 is 30 μm in thickness as in the example, the width is 500 mm, and naphthalenedicarboxylic acid is 5 to 50 mol%. A fine shape transfer film was produced using a polyester film copolymerized at a ratio.
The conveyance speed, tension, and pressing force were the same as in Example 1, and the same mold roller 4, nip roller 4 and winding core 13 as in Example 1 were used. The winding length of the unwinding roll was also prepared as 1000 m as in the example.
The support belt 22 was an endless belt having a thickness of 100 μm and a width of 500 mm made of polyester resin. Here, a pressure of 175 kN on one side was applied from the hydraulic cylinder to the nip roller 4.

  Table 1 shows the results of manufacturing the fine shape transfer film by Examples and Comparative Examples. Here, the fine shape transfer film sampling winding length refers to the winding length that could be continuously collected without causing the shape transfer to be continued due to wrinkles or meandering, in other words, the continuous fine shape. It refers to the winding length of the film roll 11 that has been transferred and wound. In addition, as a criterion for “wrinkle” in Table 1, “x” is given when buckling that does not partially transfer the fine shape occurs at the entrance of the heating roller, and “o” is given otherwise.

Also, “prism depth variation” is defined as a value obtained by measuring the depth (height) D of 10 prisms, and subtracting the minimum value from the maximum value of the measured value and dividing it by the average value. .
Various microscopes can be used for the measurement. In this example, a digital microscope VE-7800 manufactured by Keyence Corporation was used, and the magnification was observed in the range of about 150 to 600 times.

  As shown in Table 1, since the thermoplastic film 2 is adhered to the protective film 2 in Example 1 with respect to Comparative Example 1, it does not wrinkle even if thermal stress is generated due to thermal expansion due to preheating, and is 990 m. It was possible to transfer the fine shape continuously over the time. Moreover, in Example 2, the cooling efficiency of the thermoplastic film 2 increases by peeling off the protective film 3 immediately before cooling with respect to Example 1, and as a result, the accuracy of prism molding is improved and the depth D is increased. Variability decreased. Furthermore, in Example 3, the peeling force between the thermoplastic film 2 and the protective film 3 is stabilized by optimizing the peeling force as compared with Example 2, and the fluttering of the film in the cooling part is reduced to further vary the depth D. Decreased.

  On the other hand, in Comparative Example 1, wrinkles due to heat began to occur immediately after traveling, and when the film traveled 1 m, the film was removed from the rollers due to meandering due to the wrinkles, and it was impossible to transfer the fine shape continuously. In addition, as a result of observing the collected prisms, the endless belt thickness is 100 μm, and since the sum of the belt thickness and the film thickness is small with respect to the amount of rubber deformation, the pressure becomes insufficient, and the molding accuracy of the prism is reduced. The variation was also very large.

  The present invention can be applied not only to a method for producing a film to which a fine shape is transferred, but also to a method for producing a nonwoven fabric or paper to which a fine shape is similarly transferred. It is not something that can be done.

DESCRIPTION OF SYMBOLS 1 Laminated body of thermoplastic film and protective film 2 Thermoplastic film 3 Protective film 4 Mold roller 5 Nip roller 6 Film preheating means 7 Pressing means 8 Film cooling means 9 Guide roller ・ Unwinding roll ・ Fine shape transfer film roll ・ Protective film Roll, unwinding roll core, micro shape transfer film roll core, protective film roll core, idler roller, micro shape mold endless belt, prism, lenticular, rubber layer, mold preheating means, support belt P representative pitch D Typical depth δ Deformation amount in the thickness direction of the resin layer or elastomer layer on the roller surface B Contact width with the film accompanying deformation of the resin layer or elastomer layer on the roller surface p Pressure per unit area generated by pressing force t Thermoplasticity Film thickness t1 protective film Lum of lamination thicknesses of t2 thermoplastic film and the protective film

Claims (4)

The surface of a thermoplastic film having a thickness of 100 μm or less is heated to the glass transition point or more, and the surface is brought into contact with a mold roller having a fine shape provided on the surface, and at the same time, the mold roller and the roller are opposed to each other in the thickness direction. A method for producing a fine shape transfer film satisfying the following (1) to (3) in a method for producing a fine shape transfer film, wherein the film is pressed with a nip roller to transfer the fine shape to the film and cooled.
(1) The surface of at least one of the mold roller or nip roller is coated with resin or elastomer,
(2) The thermoplastic film is laminated with a protective film layer,
(3) The total thickness of the laminate of the thermoplastic film and the protective film is not less than the amount of deformation in the thickness direction of the resin layer or elastomer layer on the roller surface.
(4) The protective film is peeled off immediately before cooling the thermoplastic film. The method for producing a fine shape transfer film according to claim 1 , wherein the rubber hardness of the resin layer or the elastomer layer on the roller surface is 70 to 97 ° according to ASTM D2240: 2005 (Shore D) standard. The protective film, peel strength between the thermoplastic film and the protective film layer during peeling immediately before cooling the thermoplastic film is 0.3 mN / mm or more, claim or less 35 mN / mm 1 or The manufacturing method of the fine shape transfer film of 2 . The manufacturing method of the fine shape transfer film in any one of Claims 1-3 which satisfy | fills the following formula | equation (a).

Here, the linear expansion coefficient of the protective film is α, the temperature difference between the molding temperature and the film introduction temperature is ΔT, the thickness of the protective film is t, and the width of the thermoplastic film is b.

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