Multilayer film for thermal shaping, shaped multilayer film and method for producing the same

Abstract

To provide a multilayer film for thermal shaping which can achieve both suppression of thickness decrease in thermal transfer, and a good transfer ratio, a shaped multilayer film which has desired thickness and a good uneven shape, and a method for producing the same.SOLUTION: A multilayer film for thermal shaping includes a first layer as a shaped layer, and a second layer adjacent to the first layer, wherein the first layer contains a thermoplastic resin (P1) containing an alicyclic structure-containing polymer, the second layer contains a thermoplastic resin (P2) containing an alicyclic structure-containing polymer, the thermoplastic resins (P1) and (P2) satisfy Tg2-Tg1>20°C, Tg1 represents a glass transition temperature of the thermoplastic resin (P1), and Tg2 represents a glass transition temperature of the thermoplastic resin (P2). There are provided a shaped multilayer film and a method for producing the same.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermally shaped multilayer film, a shaped multilayer film, and a method for producing the same, and more specifically to a thermally shaped multilayer film suitable for forming a fine uneven structure on its surface by thermal transfer, as well as a shaped multilayer film and a method for producing the same. [Background technology]

[0002] A textured structure has been formed on the surface of a resin film to produce a shaped multilayer film with various properties. For example, to obtain a film with optical functions such as a light diffusion sheet, a relief hologram, a diffraction grating, or an antireflection film, a fine textured structure has been imparted to the surface of a flat resin film (for example, Patent Documents 1 and 2). The textured structure is often imparted to a resin film by thermal transfer, i.e., by superimposing a stamper having a textured shape on the heated resin film and applying pressure to it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-173914 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-253696 Summary of the Invention [Problem to be solved by the invention]

[0004] When a textured structure is imparted to a resin film by thermal transfer, pressure is applied to the resin film in the thickness direction while the resin film is heated, which can reduce the thickness of the resin film. In particular, the thickness of the resin film can be reduced by the resin constituting the resin film escaping to an area outside the area pressed by the stamper. Such a reduction in thickness can be particularly problematic when the shaped multilayer film is used for optical applications.

[0005] In order to suppress the thickness reduction, it is conceivable to reduce the pressure when applying pressure. However, when the pressure is reduced, the minute uneven structure is not sufficiently transferred, and a poor transfer rate may occur. For example, when a shape having thin and high protrusions such as a moth-eye structure is to be formed, the poor transfer rate may be particularly problematic.

[0006] Therefore, the object of the present invention is to provide a thermally shaped multilayer film that can suppress thickness reduction during thermal transfer and achieve a good transfer rate, as well as a shaped multilayer film having a desired thickness and a good uneven shape, and a method for producing the same. [Means for solving the problem]

[0007] The present inventors have conducted research to solve the above problems and have found that the above problems can be solved by using a multilayer film made of a specific material as a thermally shaping multilayer film, thereby completing the present invention. That is, the present invention provides the following.

[0008] <1> A thermally shaping multilayer film, The molded article includes a first layer that is a molded layer and a second layer adjacent to the first layer, the first layer comprises a thermoplastic resin (P1) containing an alicyclic structure-containing polymer, the second layer comprises a thermoplastic resin (P2) containing an alicyclic structure-containing polymer, The thermoplastic resins (P1) and (P2) are represented by the following formula (1): Tg2-Tg1>20℃ Formula (1) Fulfilling Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2). <2> The Tg1 is 70°C or less. <1> The thermally shaping multilayer film according to claim 1. <3> <1> or <2> A step (S1) of preparing a thermally shaped multilayer film according to the above item (1), and The method for producing a shaped multilayer film includes a step (S2) of forming a relief structure on the surface of the first layer side of the thermally shaped multilayer film by thermal transfer. <4> A shaped multilayer film, a first layer and a second layer adjacent to the first layer; the first layer comprises a thermoplastic resin (P1) containing an alicyclic structure-containing polymer, the second layer comprises a thermoplastic resin (P2) containing an alicyclic structure-containing polymer, The thermoplastic resins (P1) and (P2) are represented by the following formula (1): Tg2-Tg1>20℃ Formula (1) Fulfilling Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2). A shaped multilayer film having an uneven structure on the surface on the first layer side. <5> The Tg1 is 70°C or less. <4> The shaped multilayer film described in . [Effects of the Invention]

[0009] According to the present invention, there are provided a thermally shaped multilayer film that can suppress thickness reduction during thermal transfer and achieve a good transfer rate, as well as a shaped multilayer film having a desired thickness and a good uneven shape, and a method for producing the same. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side view schematically showing an example of the thermally shaping multilayer film of the present invention. [Figure 2] FIG. 2 is a side view schematically showing another example of the thermally shaping multilayer film of the present invention. [Figure 3] FIG. 3 is a perspective view schematically showing an example of a stamper, which is a shaping mold used for measuring the total thickness reduction amount. [Figure 4] FIG. 4 is a perspective view schematically illustrating an enlarged region R1 indicated by a dashed line of the stamper 100 in FIG. [Figure 5]FIG. 5 is a side view schematically showing an example of a shaped multilayer film (that is, a thermally shaped multilayer film to which thermal transfer has been applied) and a stamper immediately after demolding. [Figure 6] FIG. 6 is a top view showing the partitioned regions inside the shaping portion frame 200F of the shaped multilayer film obtained in the example of FIG. [Figure 7] FIG. 7 is a side view schematically showing a partially enlarged state of the shaped multilayer film 200 obtained in the example of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents. The components of the embodiments shown below can be combined as appropriate. In addition, in the drawings, the same components are designated by the same reference numerals, and their description may be omitted.

[0012] (Multi-layer film for thermal molding) The thermally shaping multilayer film of the present invention comprises a first layer, which is a layer to be shaped, and a second layer adjacent to the first layer. Fig. 1 is a side view schematically showing an example of the thermally shaping multilayer film of the present invention. In Fig. 1, the thermally shaping multilayer film 210 comprises a first layer, layer 210L1, and a second layer, layer 210L2, which is adjacent to the first layer. The thermally shaping multilayer film 210 has a surface 210U on the first layer side and a surface 210D on the second layer side, and of these, the surface 210U on the first layer side is the surface to be shaped.

[0013] The first layer contains a thermoplastic resin (P1) containing a polymer having an alicyclic structure, and the second layer (L2) contains a thermoplastic resin (P2) containing a polymer having an alicyclic structure. Preferably, the first layer consists solely of the thermoplastic resin (P1) containing a polymer having an alicyclic structure, and the second layer (L2) consists solely of the thermoplastic resin (P2) containing a polymer having an alicyclic structure.

[0014] The thermoplastic resins (P1) and (P2) satisfy the following formula (1). Tg2-Tg1>20℃ (1)

[0015] Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2). The value of Tg2 - Tg1 is greater than 20°C, preferably 25°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. The upper limit of the value of Tg2 - Tg1 is not particularly limited, but may be 100°C or lower. The inventors have found that when a concavo-convex structure is formed by thermal transfer on the surface of the first layer side of a multilayer film having such a relationship between Tg1 and Tg2, it is possible to achieve both suppression of thickness reduction during thermal transfer and a good transfer rate.

[0016] Tg1 and Tg2 are not particularly limited as long as they satisfy formula (1), and can be set to any desired value. In particular, from the viewpoint of achieving easy shaping, it is preferable that Tg1 be a temperature that is lower than a certain level. Specifically, Tg1 is preferably 110°C or lower, more preferably 70°C or lower. The lower limit of Tg2 is not particularly limited, but can be, for example, 40°C or higher.

[0017] The thickness of the first layer and the second layer, and the relationship between them, can be adjusted appropriately to achieve the desired optical properties of the shaped multilayer film after shaping and the desired thermal transfer. Specifically, the thickness of the first layer is preferably 1 μm or more, more preferably 5 μm or more, and preferably 50 μm or less, more preferably 30 μm or less. The thickness of the second layer is preferably 50 μm or more, more preferably 80 μm or more, and preferably 500 μm or less, more preferably 300 μm or less. The ratio of the thickness of the first layer to the thickness of the second layer is preferably 0.01 or more, more preferably 0.03 or more, and preferably 0.2 or less, more preferably 0.15 or less.

[0018] The heat-shaping multilayer film of the present invention may consist of only the first layer and the second layer, or may further include any other layers. Specifically, the heat-shaping multilayer film of the present invention may include a third layer adjacent to the second layer on the side opposite to the first layer. FIG. 2 is a side view schematically illustrating another example of the heat-shaping multilayer film of the present invention. In FIG. 2, the heat-shaping multilayer film 220 includes a first layer (layer 220L1), a second layer (layer 220L2) adjacent to the first layer, and a third layer (layer 220L3) adjacent to the side of layer 220L2 opposite to layer 220L1. The heat-shaping multilayer film 220 has a surface 220U facing the first layer and a surface 220D facing the third layer, one or both of which may be the surface to be shaped.

[0019] The preferred range of the thickness of the third layer may be the same as that of the first layer. The preferred range of the ratio of the thickness of the third layer to the thickness of the second layer may also be the same as that of the ratio of the thickness of the first layer to the thickness of the second layer. By further providing the third layer, it becomes possible to impart a textured structure to both surfaces of the thermally shaped multilayer film. In addition, the components contained in the second layer, such as the ultraviolet absorber, can be prevented from bleeding out of the multilayer film, which facilitates production and can also improve the durability of the multilayer film during use.

[0020] The thermally shaping multilayer film of the present invention preferably has a smooth surface. A smooth surface allows various shapes of uneven structures to be formed well. Specifically, the arithmetic mean roughness Ra of the surface of the shaping layer is preferably 0.01 μm or less, more preferably 0.005 μm or less, and ideally 0 μm, but may be greater than 0 μm.

[0021] (Thermoplastic resin (P1)) The thermoplastic resin (P1) contains an alicyclic structure-containing polymer as a thermoplastic polymer. Resins containing an alicyclic structure-containing polymer have properties such as high transparency, high heat resistance, and high mechanical strength that can maintain the shaped shape. However, when a textured structure is imparted to a resin film by thermal transfer, high pressure is required, which tends to reduce the thickness of the resin film. Here, in the present invention, by adopting a multilayer film for thermal shaping that has the above-mentioned properties, it is possible to enjoy the advantages of a resin containing an alicyclic structure-containing polymer, while simultaneously suppressing thickness reduction during thermal transfer and achieving a good transfer rate.

[0022] The alicyclic structure-containing polymer refers to a polymer containing an alicyclic structure in the main chain and / or side chain. As the alicyclic structure-containing polymer, an alicyclic structure-containing polymer containing an alicyclic structure in the main chain is preferred from the viewpoint of improving the mechanical strength and heat resistance of the multilayer film.

[0023] Examples of the alicyclic structure include saturated alicyclic hydrocarbon (cycloalkane) structures, unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures, etc. Among these, from the viewpoints of mechanical strength, heat resistance, etc., cycloalkane structures and cycloalkene structures are preferred, and cycloalkane structures are more preferred.

[0024] The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 or more, preferably 5 or more, and usually 30 or less, preferably 20 or less, more preferably 15 or less. By ensuring that the number of carbon atoms constituting the alicyclic structure falls within the above range, the mechanical strength, heat resistance, and formability of the multilayer film are well balanced, which is preferable.

[0025] The proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer can be appropriately selected depending on the intended use of the multilayer film. The proportion of repeating units containing an alicyclic structure in 100% by weight of the alicyclic structure-containing polymer is preferably 55% by weight or more, more preferably 70% by weight or more, even more preferably 90% by weight or more, and is usually 100% by weight or less. When the proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer is within the above range, the transparency and heat resistance of the multilayer film can be effectively improved.

[0026] Examples of the polymer having an alicyclic structure include norbornene polymers, monocyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrogenated products thereof. Among these, norbornene polymers and hydrogenated products thereof are preferred because of their good transparency and moldability.

[0027] Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and their hydrogenated products; and addition polymers of monomers having a norbornene structure and their hydrogenated products. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of these polymers include the polymers disclosed in, for example, JP 2002-321302 A.

[0028] Specific examples of norbornene polymers and hydrogenated products thereof include "ZEONOR" manufactured by Nippon Zeon Co., Ltd.; "ARTON" manufactured by JSR Corporation; and "TOPAS" manufactured by TOPAS ADVANCED POLYMERS.

[0029] The thermoplastic resin (P1) may contain one kind of alicyclic structure-containing polymer alone, or may contain two or more kinds of alicyclic structure-containing polymers in any combination at any ratio.

[0030] When the thermoplastic resin (P1) contains an alicyclic structure-containing polymer, it is preferable that the glass transition temperature of the alicyclic structure-containing polymer contained therein is different from the glass transition temperature of the alicyclic structure-containing polymer contained in the thermoplastic resin (P2) described below.

[0031] The thermoplastic resin (P1) may contain any polymer other than the alicyclic structure-containing polymer as long as the effects of the present invention are not significantly impaired. However, from the viewpoint of significantly exhibiting the advantages of the present invention, it is preferable that the amount of any polymer is small, and it is more preferable that the thermoplastic resin (P1) does not contain any polymer.

[0032] The thermoplastic resin (P1) may contain optional components in addition to the alicyclic structure-containing polymer. Examples of optional components include fine particles; stabilizers such as antioxidants, heat stabilizers, and near-infrared absorbers; resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments; and antistatic agents. The thermoplastic resin (P1) may contain one optional component alone or two or more optional components in any combination at any ratio. When the thermoplastic resin (P1) contains optional components, the total proportion of the optional components in the thermoplastic resin (P1) is preferably 30% by weight or less, more preferably 20% by weight or less, and even more preferably 10% by weight or less. It is usually 0% by weight or more, and may be 0.01% by weight or more, 0.1% by weight or more, or 1% by weight or more.

[0033] However, in the thermally shaping multilayer film of the present invention, it is preferable that the thermoplastic resin (P1) does not contain any substance, such as fine particles, that remains solid when the polymer is in a molten state and causes the physical properties of the first layer to become non-uniform. By not containing such a substance, good shaping of the first layer can be easily achieved.

[0034] When the heat-formable multilayer film of the present invention has a third layer in addition to the first and second layers, the third layer may contain a thermoplastic resin (P3) containing an alicyclic structure-containing polymer. Preferably, the third layer may consist solely of a thermoplastic resin (P3) containing an alicyclic structure-containing polymer. Examples of the thermoplastic resin (P3) include the same as the examples of the thermoplastic resin (P1) described above.

[0035] (Thermoplastic resin (P2)) The thermoplastic resin (P2) contains an alicyclic structure-containing polymer as a thermoplastic polymer. Examples of the thermoplastic resin (P2) and the alicyclic structure-containing polymer contained therein can be appropriately selected from the examples and preferred examples of the thermoplastic resin (P1) described above, so as to satisfy the requirements for Tg2, etc.

[0036] The thermoplastic resin (P2) may contain any polymer other than the alicyclic structure-containing polymer as long as it does not significantly impair the effects of the present invention, but from the viewpoint of significantly exhibiting the advantages of the present invention, it is preferable that the amount of the optional polymer is small. It is particularly preferable that the thermoplastic resin (P2) does not contain any optional polymer.

[0037] The thermoplastic resin (P2) may contain an ultraviolet absorber, which allows the shaped multilayer film obtained by shaping the heat-shapeable multilayer film to acquire resistance to ultraviolet light.

[0038] Examples of the ultraviolet absorber that can be used include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, acrylonitrile-based ultraviolet absorbers, and hydroxyphenyltriazine-based ultraviolet absorbers. Among them, as the ultraviolet absorber, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, and the like are preferably used. The ultraviolet absorber may be used alone or in combination of two or more kinds in any ratio.

[0039] The content of the ultraviolet absorber in the thermoplastic resin (P2) is preferably 1.0 wt% or more, more preferably 2.0 wt% or more, and preferably 15 wt% or less, more preferably 10 wt% or less. When the content of the ultraviolet absorber is equal to or greater than the lower limit of the above range, ultraviolet rays can be effectively blocked. When the content of the ultraviolet absorber is equal to or less than the upper limit of the above range, point defects in the multilayer film due to poor dispersion of the ultraviolet absorber can be suppressed, and a decrease in the strength of the multilayer film can be suppressed.

[0040] The thermoplastic resin (P2) may contain, in addition to the alicyclic structure-containing polymer, any optional component other than the UV absorber. Examples of the optional component include those listed as optional components that may be contained in the thermoplastic resin (P1). The thermoplastic resin (P2) may contain one type of optional component alone, or two or more types in any combination in any ratio.

[0041] (Evaluation of total thickness reduction and transfer rate) The thermally shaping multilayer film of the present invention has a small total thickness reduction, i.e., the amount of reduction in total thickness (i.e., the thickness across all layers of the multilayer film) during thermal transfer. Additionally, the thermally shaping multilayer film of the present invention has a high transfer rate, i.e., the rate at which the shape of the mold is accurately transferred during thermal transfer. Such total thickness reduction and transfer rate can be evaluated by measuring the amount of reduction in the total thickness of the film and the rate at which accurate shaping occurs as a result of thermal shaping performed under specified conditions. Specific examples are as follows:

[0042] FIG. 3 is a perspective view schematically illustrating an example of a stamper, which is a shaping mold used to measure total thickness reduction. In FIG. 3, stamper 100 has a square mold surface 100U, which has a number of linear grooves 100G formed therein. Grooves 100G are formed in a number parallel to a pair of sides of mold surface 100U. Because the drawings are for illustrative purposes, the scale of the components may differ from that actually used for convenience of illustration. For example, grooves 100G are shown in FIG. 3 as a small number of grooves, but in reality stamper 100 may have a much larger number of grooves.

[0043] FIG. 4 is a perspective view schematically illustrating an enlarged region R1 of the stamper 100 shown in FIG. 3, indicated by a dashed line. As shown in FIG. 4, the groove 100G has a side surface 100GS having a depth gd and a bottom surface 100GB having a width gw, with adjacent grooves 100G spaced apart by a distance iw. A standard shaping stamper 100 for evaluation may be a silicon substrate having a square mold surface 100U with sides measuring 5 cm, with the grooves 100G having a depth gd and width gw of 5 μm and a spacing iw between the grooves 100G of 10 μm. The method for molding a stamper 100 having such a mold surface 100U is not particularly limited, and any known method may be appropriately selected and employed.

[0044] Thermal transfer for evaluation can be performed by placing the stamper 100 on a thermally shaped multilayer film with the mold surface 100U in contact and then applying pressure to the resulting stack. Specifically, a thermally shaped multilayer film larger than the stamper 100 is placed on a flat base with the surface to be shaped facing up, and then the stamper 100 is placed on top of it with the mold surface 100U facing down, with the entire mold surface 100U in contact with the film. The resulting stack of layers is heated under vacuum to a predetermined temperature. The predetermined temperature is (Tg1 + 40)°C, where Tg1 is the glass transition temperature of the first layer. After the stack reaches the predetermined temperature, it is pressed under vacuum with a load of 30 kN for 5 minutes while maintaining the predetermined temperature. After pressure is applied, the hot plate is cooled, and the stack is cooled before being depressurized and demolded.

[0045] Fig. 5 is a side view schematically showing an example of a shaped multilayer film (i.e., a heat-shaping multilayer film to which thermal transfer has been applied) and a stamper immediately after demolding. Fig. 5 shows an example in which the heat-shaping multilayer film 210 shown in Fig. 1 is used as the heat-shaping multilayer film, and includes a first layer 210L1 and a second layer 210L2. The shaped multilayer film 200 has a shaped first layer 200L1 and a second layer 200L2, which correspond to the first layer 210L1 and second layer 210L2 of the heat-shaping multilayer film 210.

[0046] As a result of the thermal transfer, the shape of the mold surface 100U of the stamper 100 is transferred to the surface 200U on the first layer 200L1 side of the shaped multilayer film 200. Specifically, a large number of streak-like convex portions 201 corresponding to the grooves 100G of the mold surface 100U are formed inside the shaping portion frame 200F on the surface on the first layer 200L1 side, which corresponds to the outer shape of the mold surface 100U. Concave portions 202 are formed between the convex portions 201.

[0047] The total thickness of the obtained shaped multilayer film 200 is measured at a plurality of specific measurement points inside the shaping portion frame 200F of the obtained shaped multilayer film 200. Figure 7 is a side view schematically showing a partially enlarged state of the shaped multilayer film 200 obtained in the example of Figure 5.

[0048] To measure the total thickness of the shaped multilayer film 200, first measure the thickness, including the convex portions 201, indicated by arrow 200D using a thickness measuring device (e.g., Teclock Corporation, product name "PG-02J"), and calculate the arithmetic mean value d2 of the measurement results at multiple measurement points. Then, calculate the difference dx between the thickness d1 before thermal transfer and the thickness based on the level of the convex portions 201 and concave portions 202 when flattened, assuming that the shape of the mold surface 100U of the stamper 100 has been accurately transferred. This is the total thickness reduction. In the example of Figure 7, assuming that the shape of the mold surface 100U of the stamper 100 has been accurately transferred, the level of the convex portions 201 and concave portions 202 when flattened is 3.3 μm lower than the top surface of the convex portions 201. Therefore, the total thickness reduction dx can be calculated using the following formula (2): (dx)=(d1)-(d2)+3.3μm Formula (2)

[0049] The total thickness reduction generally reflects the amount of thermoplastic resins (P1) and (P2) that escape from inside the frame 200F to outside the frame 200F as a result of pressurization. In the case of the thermally shaping multilayer film of the present invention, it is possible to suppress the amount of such escape, particularly for the thermoplastic resin (P2) that constitutes the second layer, to a small amount. As a result, the thermally shaping multilayer film of the present invention can suppress the total thickness reduction to a small value.

[0050] Furthermore, the height of the convex portions 201 (height indicated by arrows 201H in FIG. 7) is measured at specific measurement points inside the shaping portion frame 200F of the obtained shaped multilayer film 200 using a micro-shape measuring device (for example, Kosaka Laboratory, product name "ET4000A"). The arithmetic mean of the measured values ​​is calculated and this is defined as the convex portion height (h). The percentage ratio of this value to the height of the convex portions 201 assuming that the shape of the mold surface 100U of the stamper 100 has been accurately transferred is calculated as the transfer rate (T). In the example of FIG. 7, the height of the convex portions 201 assuming that the shape of the mold surface 100U of the stamper 100 has been accurately transferred is 5 μm. Therefore, the transfer rate (T) can be calculated using the following formula (3): (T)%=((h) / 5μm)×100 Equation (3)

[0051] When the total thickness reduction and transfer rate of the thermally shaped multilayer film of the present invention are evaluated, the total thickness reduction is small, and the transfer rate can be close to 100%. Specifically, the total thickness reduction is preferably 0.5 μm or less, more preferably 0.3 μm or less, even more preferably 0.2 μm or less, and ideally 0 μm, but may be greater than 0 μm. The transfer rate can be preferably 97% or more, more preferably 98% or more, and ideally 100%.

[0052] (Method of manufacturing a thermally shaped multilayer film) The heat-shapeable multilayer film of the present invention can be produced by any production method. For example, it can be produced by melting the materials for each layer constituting the heat-shapeable multilayer film and extruding them by coextrusion. Alternatively, it can be produced by molding the materials for each layer constituting the heat-shapeable multilayer film into single-layer films and laminating them together. From the viewpoint of efficiently producing a homogeneous heat-shapeable multilayer film, extrusion molding by coextrusion is preferred.

[0053] The thermally shaped multilayer film of the present invention is preferably an unstretched film produced without a stretching step. In the case of an unstretched film, the properties do not change due to heating during thermal transfer, and a good shaped multilayer film can be easily produced.

[0054] (Method of manufacturing shaped multilayer film) The method for producing a shaped multilayer film of the present invention includes the following steps. Step (S1): A step of preparing the thermally shaping multilayer film of the present invention. Step (S2): A step of forming a concave-convex structure on the surface of the first layer side of the thermally shaping multilayer film by thermal transfer.

[0055] Step (S1) may be the same as the step described above for the method for producing a heat-shapeable multilayer film. Step (S2) can be carried out by the same process as the thermal transfer process for evaluating the total thickness reduction and transfer rate described above, or by a process with appropriately changed conditions, except that a mold having a mold surface capable of imparting a desired shape is used instead of an evaluation stamper.

[0056] When the thermally shaping multilayer film has a third layer in addition to the first layer, if desired, the third layer may also be provided with a concave-convex structure in the same manner as in step (S2).

[0057] (Shaped multilayer film) The shaped multilayer film of the present invention comprises a first layer and a second layer adjacent to the first layer, the first layer comprising a thermoplastic resin (P1), the second layer comprising a thermoplastic resin (P2), and has a textured structure on the surface of the first layer side. The thermoplastic resin (P1) and the thermoplastic resin (P2) may be the same as those in the thermally shaped multilayer film. The shaped multilayer film of the present invention can be produced by the above-described method for producing a shaped multilayer film using the above-described thermally shaped multilayer film of the present invention. When a thermally shaped multilayer film having a third layer in addition to the first layer is used for production, a textured structure can be formed in the third layer as well, if desired, to produce a shaped multilayer film having a textured structure on both sides.

[0058] The uneven structure of the shaped multilayer film of the present invention can be a uneven structure of a desired shape that exhibits desired properties such as desired optical properties, etc. The arithmetic mean roughness Ra of the surface having the uneven structure is preferably 1000 μm or less, more preferably 100 μm or less, and is preferably 0.001 μm or more, more preferably 0.01 μm or more.

[0059] The shaped multilayer film of the present invention can be used as a functional film utilizing the properties resulting from the uneven surface structure, such as a light diffusion sheet, a relief hologram, a diffraction grating, an anti-reflection film, or other optically functional film. [Example]

[0060] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below, and can be practiced with any modifications within the scope of the claims of the present invention and their equivalents.

[0061] In the following description, the units "%" and "parts" that represent amounts are by weight unless otherwise specified. Furthermore, the operations described below were carried out at room temperature (20°C ± 15°C) and atmospheric pressure (1 atm) unless otherwise specified.

[0062] [Evaluation method] (Thickness of each layer of multilayer film) The multilayer film was cut, and the cross section was cut using a microtome ("RV-240" manufactured by Yamato Koki Co., Ltd.) to prepare the sample. Images of the film cross section were taken using an electron microscope, and the thickness ratio of each layer was measured. The thickness of each layer was calculated from these results and the separately measured thickness of the entire multilayer film (the average value of the thickness measured at 25 points before molding when measuring the total thickness reduction).

[0063] (glass transition temperature) The glass transition temperatures of the materials (thermoplastic resins (P1) and (P2)) forming each layer of the film were measured under a nitrogen atmosphere using a Hitachi DSC7020. The conditions were in accordance with JIS K7121-1987, with a heating rate of 20°C / min, and the glass transition onset temperature was determined by extrapolation. The glass transition temperature in the present invention refers to this glass transition onset temperature. The sample was first heated to 300°C for 10 minutes under a nitrogen atmosphere, and then quenched with liquid nitrogen, before measuring the glass transition temperature.

[0064] (Total thickness reduction and transfer rate) A silicon substrate as shown schematically in Figures 3 and 4 was prepared as the shaping stamper 100. The stamper 100 had a square shape with sides of 5 cm, and grooves 100G formed in its mold surface 100U had a depth gd and width gw of 5 µm, and an interval iw between the grooves 100G of 10 µm.

[0065] An alignment sheet was prepared on a transparent sheet with a diagram drawn on it, in which the shaping portion frame 200F shown in Figure 6, which has a side length of 5 cm, was divided into 25 5 x 5 regions, namely, regions (1.1) to (1.5), (2.1) to (2.5), (3.1) to (3.5), (4.1) to (4.5), and (5.1) to (5.5). A square shape with a side length of 5.5 cm was drawn near the center of the test specimens obtained in the Examples and Comparative Examples. The test specimens were placed on the stage of a thickness measuring instrument (PG-02J, manufactured by Teclock Corporation), and an alignment sheet was placed on top of the test specimen. The alignment sheet was positioned so that the shape of the shaping frame 200F was located 0.25 cm inside the 5.5 cm side shape on the test specimen, and the sides of these shapes were parallel and in an even positional relationship. While maintaining the relative positions of the test piece and the alignment sheet without shifting them, the test piece and the alignment sheet were moved so that the measurement position of the test piece matched the measurement position of the measuring instrument, and then the alignment sheet was removed and the thickness of the test piece was measured. Such measurements were performed at 25 points, each at the center of the 25 regions, and the average of the measured values ​​was calculated and used as the thickness of the test piece before shaping (d1).

[0066] A 5-inch silicon wafer with a smooth surface was placed on the lower hot plate of a vacuum heat press (Mikado Technos Co., Ltd., Model No. VN40-2020) as a base. The test piece was placed on top of this with the shaping surface (the surface on the first layer side) facing up, covering the base and with the square frame of the drawn pattern positioned at the center of the base. Furthermore, a stamper 100 was placed on top of the test piece with the mold surface 100U facing downwards. The stamper 100 was positioned 0.25 cm inside the square frame of the test piece when viewed from above, similar to the positioning of the alignment sheet. A silicone rubber sheet was then placed on top of this so as to completely cover the stamper 100. The stack of layers was heated under vacuum using the hot plates above and below the stack until it reached a predetermined temperature. The predetermined temperature was set to (Tg1 + 40)°C, where Tg1 is the glass transition temperature of the first layer in the test piece. After the deposit reached a predetermined temperature, it was pressed with a load of 30 kN for 5 minutes while maintaining the predetermined temperature under vacuum. After pressing, the hot plate was cooled, and when the temperature of the deposit dropped below 45°C, the pressure was released and the mold was demolded. As a result, the shape of the mold surface 100U of the stamper 100 was transferred to the shaping surface of the test piece, and a shaped multilayer film 200 was obtained as shown schematically in Figure 5. The shaped multilayer film 200 had a shape with numerous streak-like protrusions 201 inside the shaping portion frame 200F corresponding to the outer shape of the mold surface 100U of the stamper 100.

[0067] The interior of the shaping portion frame 200F of the obtained shaped multilayer film 200 was divided into 25 5 x 5 regions as shown in Figure 6, similar to the diagram drawn on the alignment sheet. Of these, the thickness of the shaped multilayer film 200 (thickness including the convex portion 201, indicated by arrow 200D in Figure 7) was measured at the center of the regions (1.2), (1.4), (2.1), (2.3), (2.5), (3.2), (3.4), (4.1), (4.3), (4.5), (5.2), and (5.4) using a thickness measuring device (manufactured by Teclock Corporation, product name "PG-02J"), and the arithmetic mean of the measured values ​​was calculated, which was used as the post-shaping thickness (d2). Based on this value and the pre-shaping specimen thickness (d1) measured before shaping, the total thickness reduction (dx) was calculated according to the following formula (2). (dx)=(d1)-(d2)+3.3μm Formula (2)

[0068] Of the 25 regions shown in FIG. 6, the heights of the convex portions 201 (heights indicated by arrows 201H in FIG. 7) at the centers of regions (2.2), (2.4), (3.3), (4.2), and (4.4) were measured. The measurements were performed using a microstructure measuring device (manufactured by Kosaka Laboratory, product name "ET4000A"). The arithmetic mean of the measured values ​​was calculated, and this was taken as the convex portion height (h). Based on this value, the transfer rate (T) was calculated according to the following formula (3). (T)%=((h) / 5μm)×100 Equation (3)

[0069] (surface roughness) The arithmetic mean roughness Ra of the surface on the mold-imparting layer side of the test pieces obtained in the examples and comparative examples was measured using a micro-profile measuring device (manufactured by Kosaka Laboratory Co., Ltd., product name "ET4000A") The arithmetic mean roughness Ra of all test pieces was 0.010 μm or less.

[0070] (Example 1, Example 7 and Comparative Example 7) A three-type, three-layer multilayer extruder (manufactured by Collin) equipped with a feed block was prepared. This extruder was a device capable of extruding three types of molten resin to form a multilayer film having a layer structure of (first layer) / (second layer) / (third layer).

[0071] The thermoplastic resins shown in Table 1 for forming the first layer (P1) and the thermoplastic resin for forming the second layer (P2) were fed into an extruder, melted, extruded from the extruder die in the form of a film, and cooled on a cooling drum. The extrusion processing temperature (maximum temperature of the extruder cylinder heating zone) and cooling drum temperature for each resin were as shown in Table 1. This procedure allowed continuous production of a multilayer film having a (first layer) / (second layer) layer structure. In this example, a third layer was not formed.

[0072] The resulting multilayer film was cut into square test pieces with sides of approximately 6 cm, and the thickness ratio of each layer was measured. A thermal shaping test was then conducted using the surface of the first layer of the test piece as the shaping layer, and the total thickness reduction and transfer rate were determined. The thickness of each layer was also calculated from the measured thickness before shaping.

[0073] Examples 2 to 6 Using a three-type, three-layer multilayer extruder (the same as that used in Example 1), the resins shown in Table 1 were fed into the extruder as the thermoplastic resin (P1) for forming the first layer, the thermoplastic resin (P2) for forming the second layer, and the thermoplastic resin (P3) for forming the third layer, as shown in Table 1, and melted. The resins were extruded from the extruder die in the form of a film and cooled on a cooling drum. The extrusion processing temperature (maximum temperature of the extruder cylinder heating zone) and cooling drum temperature for each resin were as shown in Table 1. This procedure resulted in the continuous production of a multilayer film having a layer structure of (first layer) / (second layer) / (third layer). The thicknesses of the first to third layers were measured and found to be as shown in Table 1.

[0074] The resulting multilayer film was cut into square test pieces with sides of approximately 6 cm, and the thickness ratio of each layer was measured. A thermal shaping test was then conducted using the surface of the first layer of the test piece as the shaping surface, and the total thickness reduction and transfer rate were determined. The thickness of each layer was also calculated from the measured thickness before shaping.

[0075] (Comparative Examples 2 to 6) Using a three-type three-layer multi-layer extruder (the same as that used in Example 1), the resin shown in Table 1 was fed into the extruder as the thermoplastic resin (P1) for forming the first layer, melted, extruded from the extruder die in the form of a film, and cooled on a cooling drum. The resin extrusion processing temperature (maximum temperature of the extruder cylinder heating zone) and the cooling drum temperature were as shown in Table 1. This procedure continuously produced a monolayer film having only the first layer. In this example, the second and third layers were not formed. The thickness of the first layer was measured and found to be as shown in Table 1.

[0076] The obtained monolayer film was cut out to obtain a square test piece with a side length of approximately 6 cm. A thermal shaping test was performed using one surface of the test piece as a shaping layer to determine the total thickness reduction and transfer rate. The measured thickness before shaping was taken as the thickness of the monolayer film.

[0077] Tables 1 and 2 show the outlines and results of the Examples and Comparative Examples.

[0078] [Table 1]

[0079] [Table 2]

[0080] The meanings of the abbreviations in the table are as follows: L1~L3: 1st layer ~ 3rd layer P1~P3: Thermoplastic resin (P1)~(P3) H1: Hydrogenated norbornene polymer: manufactured by Zeon Corporation, glass transition temperature 69°C H2: Hydrogenated norbornene polymer: manufactured by Zeon Corporation, glass transition temperature 99°C H3: Hydrogenated norbornene polymer: manufactured by Zeon Corporation, glass transition temperature 125°C H4: Hydrogenated norbornene polymer: manufactured by Zeon Corporation, glass transition temperature 134°C H5: Hydrogenated norbornene polymer: manufactured by Zeon Corporation, glass transition temperature 160°C

[0081] Comparing the results of the above Examples and Comparative Examples, the transfer rates are roughly the same in the Examples and Comparative Examples, while the total thickness reduction in the Examples is significantly lower than in the Comparative Examples. This demonstrates that the thermally shaped multilayer film of the present invention can achieve both suppression of thickness reduction during thermal transfer and a good transfer rate. [Explanation of symbols]

[0082] 100 Stamper 100G groove 100GB bottom 100GS side 100U mold surface 200 Shaped multilayer film 200D Thickness including protrusions 200F Forming frame 200L1 1st layer 200L2 2nd layer 200U First layer surface 201 Convex 201H Convex height 202 recess 210 Multilayer film for thermal molding 210D Second layer surface 210L1 1st layer 210L2 2nd layer 210U First layer surface 220 Multilayer film for thermal molding 220D Third layer surface 220L1 1st layer 220L2 2nd layer 220L3 3rd layer 220U First layer surface gd Groove depth gw Groove width iw Groove distance R1 area (1.1)~(1.5), (2.1)~(2.5), (3.1)~(3.5), (4.1)~(4.5), (5.1)~(5.5) area

Claims

1. A thermally shaping multilayer film, The molded article includes a first layer that is a molded layer and a second layer adjacent to the first layer, the first layer contains a thermoplastic resin (P1) containing an alicyclic structure-containing polymer, the second layer comprises a thermoplastic resin (P2) containing an alicyclic structure-containing polymer, The thermoplastic resins (P1) and (P2) are represented by the following formula (1): Tg2-Tg1>20℃ Formula (1) Fulfilling Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2).

2. 2. The heat-forming multilayer film according to claim 1, wherein the Tg1 is 70°C or less.

3. A step (S1) of preparing the thermally shaping multilayer film according to claim 1 or 2; and A method for producing a shaped multilayer film, comprising a step (S2) of forming a relief structure on the surface of the first layer side of the thermally shaped multilayer film by thermal transfer.

4. A shaped multilayer film, a first layer and a second layer adjacent to the first layer; the first layer contains a thermoplastic resin (P1) containing an alicyclic structure-containing polymer, the second layer comprises a thermoplastic resin (P2) containing an alicyclic structure-containing polymer, The thermoplastic resins (P1) and (P2) are represented by the following formula (1): Tg2-Tg1>20℃ Formula (1) Fulfilling Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2). A shaped multilayer film having a roughened structure on the surface of the first layer side.

5. The shaped multilayer film according to claim 4, wherein the Tg1 is 70°C or less.

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