Biaxially oriented polylactic acid film and laminated film

Abstract

The present invention relates to a biaxially oriented polylactic acid film formed from a film-forming material containing polylactic acid. In a spectrum measured by total reflection Fourier transform infrared spectroscopy, a mesophase orientation parameter (peak intensity ratio at 757 cm-1 / 2996 cm-1) of the polylactic acid film is 4.0 or less. In the polylactic acid film, the internal Haze is preferably 6% or less, it is preferable that the breaking stress in the width direction is 100 MPa or more and the ratio of the breaking stress in the longitudinal direction to the breaking stress in the width direction is 0.7 or less, the thermal shrinkage rate in the longitudinal direction when heated at 150°C for 30 minutes is preferably 10% or less, and the mass ratio of L-lactic acid / D-lactic acid is preferably 100 / 0 to 85 / 15. According to the present invention, a polylactic acid film having excellent transparency and processability can be provided using a biodegradable polylactic acid derived from a biomass source.

Description

Biaxially oriented polylactic acid film and laminated film

[0001] The present invention relates to a biaxially oriented polylactic acid film formed from a film-forming material containing polylactic acid, and a laminated film containing the same.

[0002] Films made from polylactic acid (hereinafter sometimes referred to as "PLA") resin are being developed as an alternative to conventional fossil fuels because they are derived from biomass materials and are biodegradable, and are expected to replace polyethylene terephthalate, nylon, polyolefins, etc. However, compared to these materials, PLA is inferior in strength and heat resistance, regardless of whether it is used for industrial or packaging purposes. Therefore, efforts have been made to improve its mechanical properties and heat resistance by utilizing oriented crystallization through stretching.

[0003] For example, Patent Document 1 discloses a film suitable for thermoformability (heat resistance) and printability, which is obtained by controlling the planar orientation coefficient by controlling the stretching temperature and ratio and increasing the proportion of D-lactic acid. Patent Document 2 discloses a molded product having improved heat resistance and impact resistance by controlling the crystal formability through the addition of a crystal nucleating agent. Patent Documents 3 to 6 also disclose polylactic acid films. Patent Document 7 discloses a laminated film having a pressure-sensitive adhesive layer based on a polylactic acid film that eliminates internal crazes by controlling the degree of orientation through the stretching temperature and ratio, thereby achieving transparency, strength, heat resistance, and processability.

[0004] Japanese Patent Application Laid-Open No. 2005-15783 Japanese Patent Application Laid-Open No. 2009-249443 Japanese Patent Application Laid-Open No. 2003-170560 Japanese Patent Application Laid-Open No. 8-52171 Japanese Patent Application Laid-Open No. 2000-281816 Japanese Patent Application Laid-Open No. 2006-35787 Japanese Patent No. 5775831

[0005] In recent years, environmental impact reduction efforts, including those aimed at achieving the SDGs and carbon neutrality, have become increasingly necessary, and the use of biomass-derived resins, such as PLA, has been actively explored worldwide. However, due to its fragility, it has been found that stretching PLA can cause crazes within the film. These crazes can lead to poor appearance (haze deterioration) and cracking during processing. Through extensive research, the inventors have found that internal crazes are particularly pronounced when stretching films containing inorganic particles. Furthermore, while controlling the stretching temperature and ratio during uniaxial and biaxial stretching processes is generally known to effectively control orientation and crystallinity, which are believed to improve mechanical properties and heat resistance, polylactic acid resins are subject to significant orientation crystallization due to stretching temperature. Low-temperature stretching, in particular, can cause crazes due to excessive stress, while high-temperature stretching can cause defects such as breakage and holes due to embrittlement caused by crystallization. In particular, in sequentially biaxially stretched films, the higher-order structures formed in the uniaxial and biaxial stretching steps influence each other, and it has been found that precise control of the higher-order structure is required to suppress crazes. Furthermore, when such biaxially oriented films or sheets are used as substrates for adhesive tapes or the like, there is a problem that cracks, tears, etc. occur in the adhesive tapes or the like during production or processing of the adhesive tapes or the like.

[0006] Patent Document 1 discloses a method for improving heat resistance, but the heat resistance evaluation is limited to 120°C, and no disclosure is made about a higher heat resistance environment of 150°C. Furthermore, there is no mention of crazes occurring inside the film due to stretching. Patent Document 2 does not mention crazes due to stretching, and its haze reduction effect is limited. Patent Document 3 solves the problem of void generation by antiblocking agents, which causes haze deterioration, by using a void inhibitor, but the resulting film is not sufficiently transparent. Patent Document 4 discloses a lens protective film that has excellent transparency, but the area ratio in the stretching process is low, so it is said that the balance between transparency and mechanical strength and heat resistance is not satisfactory. Patent Document 5 discloses a method for improving slipperiness and processability by adding inorganic particles, but does not achieve a haze equivalent to that of L-lactic acid alone. Furthermore, while low haze is achieved only when the amount of inorganic particles added is reduced, the slipperiness necessary for proper processing is impaired. Patent Document 6 describes a method for producing a moisture-proof coated polylactic acid film and also mentions sequential biaxially stretched film, but the high haze makes it difficult to say that the stretching temperature and ratio are optimal for suppressing craze. Furthermore, biaxially oriented polylactic acid films have poor adhesion to printing inks, hard coats, etc., and can be poor in processability. Furthermore, biaxially oriented polylactic acid films have high electrical insulation properties, which makes them prone to charging, which can result in poor processability.

[0007] Furthermore, due to its molecular structure, PLA tends to have lower mechanical properties, heat resistance, and chemical resistance than other resins, making it difficult to use in a variety of applications. Patent Document 7 discloses a film that has improved mechanical properties, heat resistance, and chemical resistance by melt-extruding it into a film or sheet and then promoting crystallinity during the crystallization process. This effect eliminates the problem of breakage, tearing, etc., occurring in adhesive tapes and the like when used as a substrate for adhesive tapes and the like during manufacturing and processing of the adhesive tapes and the like.

[0008] However, while Patent Document 7 proposes environmentally friendly PLA film as a base material, it does not propose environmentally friendly constituent materials for the laminated pressure-sensitive adhesive layer, and therefore does not sufficiently contribute to reducing the environmental load. Furthermore, Patent Document 7 makes no mention of biomass conversion for the pressure-sensitive adhesive layer or release layer laminated on the laminate film, and it is difficult to say that all of the resins that make up the laminate film contribute to reducing the environmental load.

[0009] The object of the present invention is to provide a biaxially oriented polylactic acid film that uses biomass-derived and biodegradable polylactic acid to eliminate internal crazes that occur when PLA is stretched, which is not disclosed in the above-mentioned prior art, and that combines transparency with strength, heat resistance, and processability, and a laminate film that includes this as a base film.

[0010] As a result of extensive research into polylactic acid films, the present inventors discovered that controlling the degree of orientation, including the crystalline / amorphous intermediate layer (mesolayer) of a polylactic acid film, can suppress the occurrence of crazes during stretching, thereby reducing haze after stretching and suppressing cracking during processing. Furthermore, by controlling the crystallinity at the time of uniaxial stretching, the stretching temperature can be increased compared to the stretching temperature near the glass transition temperature used in conventional biaxial stretching methods, thereby achieving high crystallinity and improving heat resistance. As a result, the biaxially oriented polylactic acid film of the present invention has succeeded in achieving both transparency and processability without compromising conventional strength and heat resistance.

[0011] That is, in order to solve the above-mentioned problems, the present invention provides a biaxially oriented polylactic acid film formed from a film-forming material containing polylactic acid having the following configuration. Furthermore, the present invention also provides a laminated film containing the biaxially oriented polylactic acid film. [Item 1] A biaxially oriented polylactic acid film formed from a film-forming material containing polylactic acid, wherein the mesophase orientation parameter (757 cm) of the polylactic acid film is measured in a spectrum by the total reflection method of Fourier transform infrared spectroscopy. -１ / 2996cm -１[Item 2] The biaxially oriented polylactic acid film according to Item 1, having an internal haze of 6% or less. [Item 3] The biaxially oriented polylactic acid film according to Item 1 or 2, having a width direction breaking stress of 100 MPa or more and a ratio of the longitudinal direction breaking stress to the width direction breaking stress of 0.7 or less. [Item 4] The biaxially oriented polylactic acid film according to any one of Items 1 to 3, having a longitudinal direction heat shrinkage rate of 10% or less when heated at 150°C for 30 minutes. [Item 5] The biaxially oriented polylactic acid film according to any one of Items 1 to 4, having an L-lactic acid / D-lactic acid mass ratio of 100 / 0 to 85 / 15. [Item 6] The biaxially oriented polylactic acid film according to any one of Items 1 to 5, wherein the biaxially oriented polylactic acid film has an arithmetic mean roughness (Sa) of 10 nm or less and a maximum protrusion height (P) of 200 nm or less on at least one surface. [Item 7] A laminate film having a base film and a release layer on at least one surface of the base film, wherein the base film comprises the biaxially oriented polylactic acid film according to any one of Items 1 to 6. [Item 8] The laminate film according to Item 7, wherein the release layer is formed from a release layer-forming material containing at least one release component selected from the group consisting of silicone resin, fluororesin, alkyd resin, wax, and aliphatic olefin. [Item 9] The laminate film according to Item 7 or 8, wherein the release layer has a maximum protrusion height (P) of 200 nm or less on the surface and an arithmetic mean roughness (Sa) of 10 nm or less on the surface. [Item 10] The laminate film according to any one of Items 7 to 9, wherein the release layer is a release film for producing a ceramic green sheet. [Item 11] A laminate film having a base film and a resin layer on at least one side of the base film, wherein the resin layer is formed from a resin layer-forming material containing an aqueous resin, and the base film comprises the biaxially oriented polylactic acid film according to any one of Items 1 to 6. [Item 12] The laminate film according to Item 11, wherein the resin layer has a surface free energy γs of 40 mN / m or more. [Item 13] The biaxially oriented laminate polylactic acid film according to Item 11 or 12, wherein the resin layer is formed by an in-line coating method.[Item 14] The laminate film according to any one of Items 11 to 13, wherein the resin layer-forming material contains an antistatic agent. [Item 15] The surface resistivity of the surface of the resin layer is 1.0 × 10 １４Item 16: The biaxially oriented laminate polylactic acid film according to Item 14, wherein the antistatic agent content is 5% by mass or more and 45% by mass or less, relative to the aqueous resin of the resin layer-forming material. Item 17: The laminate film according to any one of Items 14 to 16, wherein a release layer is provided on at least one surface of the laminate film. Item 18: The laminate film according to Item 17, wherein the release layer is formed from a release layer-forming material containing at least one release component selected from the group consisting of silicone resin, fluororesin, alkyd resin, wax, and aliphatic olefin. Item 19: The laminate film according to Item 17 or 18, wherein the release layer has a maximum protrusion height (P) of 200 nm or less and an arithmetic mean roughness (Sa) of 10 nm or less on the surface of the release layer. Item 20: The laminate film according to any one of Items 17 to 19, wherein the release layer is a release film for producing a ceramic green sheet. [Item 21] A laminate film having a base film and a pressure-sensitive adhesive layer on at least one side of the base film, wherein the base film comprises the biaxially oriented polylactic acid film according to any one of Items 1 to 6. [Item 22] The laminate film according to Item 21, wherein the pressure-sensitive adhesive layer contains a biomass-derived raw material. [Item 23] The laminate film according to Item 22, wherein the pressure-sensitive adhesive layer is a layer containing an acrylic polymer, and at least one acrylic monomer serving as a monomer component of the acrylic polymer is at least one selected from the group consisting of acrylic acid and methacrylic acid, which are biomass-derived raw materials. [Item 24] The laminate film according to Item 11, wherein the base film has a pressure-sensitive adhesive layer on one side and a release layer on the side opposite the pressure-sensitive adhesive layer. [Item 25] The laminate film according to Item 24, wherein the release layer is formed from a release layer-forming material containing at least one release component selected from the group consisting of silicone resin, fluororesin, alkyd resin, wax, and aliphatic olefin. [Item 26] The laminate film according to item 24 or 25, wherein the maximum protrusion height (P) of the surface of the release layer is 200 nm or less, and the arithmetic mean roughness (Sa) of the surface of the release layer is 10 nm or less.

[0012] The biaxially oriented polylactic acid film of the present invention has excellent transparency and processability due to the control of mesophase orientation. Therefore, it has good dimensional stability during processing at high temperatures, and is suitable not only for packaging materials but also for optical applications requiring high transparency and industrial components such as release paper. Furthermore, because it is made from biomass-derived raw materials and is biodegradable, it is possible to provide an excellent biaxially oriented polylactic acid film that takes into consideration the recent SDGs, and to provide laminate films using this as a base film and including release layers, resin layers, pressure-sensitive adhesive layers, etc.

[0013] Furthermore, when the laminate film has a pressure-sensitive adhesive layer, by using a biomass-derived raw material for the pressure-sensitive adhesive layer, it is possible to provide a laminate film in which both the base film and the pressure-sensitive adhesive layer are environmentally friendly, which contributes greatly to reducing the environmental load. Furthermore, when the laminate film has a resin layer, by incorporating an antistatic agent in the resin layer, it is possible to impart antistatic properties.

[0014] A diagram explaining the measurement method using the ATR-FTIR method. Cross-sectional image of the film of Example 2 taken by SEM. Cross-sectional image of the film of Comparative Example 1 taken by SEM. Cross-sectional image of the film of Comparative Example 3 taken by SEM.

[0015] The biaxially oriented polylactic acid film of the present invention is formed from a film-forming material containing polylactic acid. In this biaxially oriented polylactic acid film, the mesophase orientation parameter (757 cm) in the FT-IR spectrum -１ / 2996cm -１ It is preferable that the biaxially oriented polylactic acid film of the present invention has an internal haze of 6% or less, a breaking stress in the width direction of 100 MPa or more, and a ratio of the breaking stress in the longitudinal direction to the width direction (longitudinal direction / width direction) of 0.7 or less. It is also preferable that the heat shrinkage rate in the longitudinal direction when heated at 150°C for 30 minutes is 10% or less. It is also preferable that the mass ratio of L-lactic acid / D-lactic acid is 100 / 0 to 85 / 15.

[0016] A common method for producing biaxially oriented films using crystalline polymer materials by sequential biaxial stretching is to first obtain an unstretched sheet in a glassy (amorphous) state by melt extrusion, for example, in the case of PET (polyethylene terephthalate). The longitudinal stretching is then heated above the glass transition temperature and stretched several times to obtain a longitudinally uniaxially stretched film. The transverse stretching is then introduced into a tenter and heated above the glass transition temperature while stretching several times, followed by crystallization (solidification) in a heat setting process to impart dimensional stability. However, in the case of polylactic acid resin, it has been found that differences in transparency (i.e., haze) occur within the scope of the above-mentioned film-forming method. Specifically, for example, in the case of polylactic acid alone, crazes appear within the film depending on the thermal history and stretching ratio during the stretching process, resulting in increased haze and internal haze. Furthermore, when inorganic particles are included, crazes appear more significantly within the film, worsening the overall haze. As a factor contributing to these problems, the inventors focused on the deterioration of haze due to the progression of higher-order structure, i.e., molecular orientation and crystallization. However, since molecular orientation and crystallinity alone do not provide a correlation with haze, they also focused on the mesophase, which represents the crystalline / amorphous intermediate layer, as a more detailed higher-order structure. After extensive investigation, they found a certain relationship between the mesophase orientation parameter and haze. In order to obtain a more transparent polylactic acid film using the sequential biaxial stretching method, it is preferable to control the crystallinity at the time of longitudinal stretching and the crystallinity in the subsequent transverse stretching. The inventors considered the possibility that an increase in mesophase orientation would be equivalent to excessive orientation, leading to the occurrence of crazes due to the destruction of molecular chains.

[0017] (Biaxially oriented polylactic acid film) First, a biaxially oriented polylactic acid film formed from a film-forming material containing polylactic acid will be described.

[0018] (Polylactic Acid) The polylactic acid preferably used in the present invention is obtained by ring-opening polymerization of lactide using a compound having a hydroxyl group as an initiator in the presence of a specific catalyst. Examples of the specific catalyst include tin and aluminum. Polylactic acid can contain an L-lactic acid component and a D-lactic acid component as copolymer or blend components. In polylactic acid films and resin compositions, the mass ratio of L-lactic acid (hereinafter referred to as L-form) to D-lactic acid (hereinafter referred to as D-form) is preferably 100 / 0 to 85 / 15, more preferably 100 / 0 to 90 / 10, even more preferably 100 / 0 to 90 / 10, and particularly preferably 100 / 0 to 95 / 5. When the L-lactic acid (hereinafter referred to as L-form) to D-lactic acid (hereinafter referred to as D-form) ratio is within the above range, high crystallinity is obtained, and improvements in film properties such as improved film physical properties and reduced heat shrinkage are easily achieved, which is preferable. Polylactic acid may be copolymerized with a hydroxy acid component other than lactic acid. Examples of the hydroxy acid component other than lactic acid include glycolic acid, 3-hydroxypropionic acid, and 6-hydroxycaproic acid (ε-caprolactone).

[0019] The polylactic acid of the present invention preferably has a glass transition point of 40 to 70°C, a melting point of 150 to 180°C, and is preferably capable of orientation crystallization. The melting point is more preferably 155°C or higher, and even more preferably 160°C or higher. The glass transition point and melting point can be measured using a differential scanning calorimeter (DSC) or the like. The presence or absence of crystallinity can be confirmed by the presence or absence of a crystallization peak during the heating process or the cooling process after melting using DSC.

[0020] The reduced viscosity (ηsp / c) of the polylactic acid-containing film-forming material used in the present invention is preferably in the range of 1.0 dl / g or more and 3.0 dl / g or less. When the reduced viscosity is 1.0 dl / g or more, the melt of the polylactic acid-containing film-forming material can be stably extruded onto a cooling drum during film production, and tearing of the resulting biaxially oriented polylactic acid film can be prevented. When the reduced viscosity is 3.0 dl / g or less, the increase in filtration pressure when the melt of the polylactic acid-containing film-forming material is filtered during film production is small, facilitating high-precision filtration.

[0021] The reduced viscosity (ηsp / c) of the biaxially oriented polylactic acid film of the present invention is preferably in the range of 1.0 dl / g or more and 2.5 dl / g or less. When the reduced viscosity is 1.0 dl / g or more, breakage does not occur frequently during the stretching process, which is preferable. When the reduced viscosity is 2.5 dl / g or less, cuttability when cutting to a predetermined product width is good and dimensional defects do not occur, which is preferable.

[0022] The polylactic acid-containing film-forming material used in the present invention may be blended with a polyester other than copolymerized polylactic acid or polylactic acid. The polyester other than polylactic acid is preferably an aliphatic polyester, such as polybutylene succinate, polybutylene succinate adipate, polybutylene succinate lactate, polybutylene adipate terephthalate, or polyethylene succinate.

[0023] Even when a polyester component other than lactic acid is contained, such as when a copolymerized polylactic acid is used or when a polyester other than polylactic acid is blended, the lactic acid component preferably accounts for 85 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 97 mol% or more of the total polyester component (the total amount of the hydroxycarboxylic acid component, the dicarboxylic acid component, and the glycol component). Furthermore, even when a polyester component other than lactic acid is contained, the glass transition point, melting point, and reduced viscosity of the copolymerized polylactic acid and the blend are preferably within the above-mentioned ranges.

[0024] The polylactic acid-containing film-forming material used in the present invention can contain one or more additives, such as inert particles (e.g., inorganic particles, heat-resistant polymer particles, crosslinked polymer particles), fluorescent brighteners, UV inhibitors, infrared absorbing dyes, heat stabilizers, surfactants, and antioxidants, depending on the intended use. Examples of antioxidants that can be used include aromatic amine-based and phenol-based antioxidants. Examples of stabilizers that can be used include phosphorus-based stabilizers (e.g., phosphoric acid and phosphate ester-based), sulfur-based stabilizers, and amine-based stabilizers. The polylactic acid content of the film-forming material is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, particularly preferably 98% by mass or more, and most preferably 99% by mass or more. Furthermore, the glass transition point, melting point, and reduced viscosity measured for the film-forming material are preferably within the above-mentioned ranges.

[0025] (Method for Producing Biaxially Oriented Polylactic Acid Film) The biaxially oriented polylactic acid film of the present invention is preferable in terms of mechanical strength, chemical resistance, heat resistance, and the like.

[0026] The film-forming material containing polylactic acid in the present invention can be processed into an unstretched sheet by various methods, and then biaxially stretched to obtain a polylactic acid film. As a method for producing the unstretched sheet, a melt extrusion method can be used in addition to a solution casting method. The melt extrusion method is preferred in the present invention.

[0027] The melting temperature of the film-forming material is preferably in the range of 150 to 250°C, more preferably 180 to 245°C, and even more preferably 200 to 240°C. A temperature of 150°C or higher is preferred because it provides an appropriate melt viscosity and increases productivity. A temperature of 250°C or lower is preferred because it can suppress thermal degradation of polylactic acid.

[0028] The die temperature during melt extrusion is the same as described above, but is preferably in the range of 150 to 300°C, more preferably 170 to 290°C, and even more preferably 180 to 240°C. When the die temperature during melt extrusion is 150°C or higher, the melt viscosity falls within an appropriate range, allowing stable extrusion. When the temperature is 300°C or lower, thermal decomposition of the resin can be suppressed.

[0029] The biaxially oriented polylactic acid film of the present invention can be produced according to a typical polyester film production method, and preferably does not contain additives such as plasticizers or crystallization accelerators. For example, a polyester resin is melted and extruded into a sheet of unoriented polyester, which is then uniaxially stretched in the longitudinal direction (machine direction) at a temperature above the glass transition temperature using a roll speed differential, followed by biaxial stretching in the transverse direction using a tenter, followed by heat treatment. Specifically, for example, in the machine direction stretching step, the film is heated and preferably stretched 1.1 to 6.0 times between two or multiple rolls with different peripheral speeds. From the viewpoint of strength and quality after biaxial stretching, the lower limit of the machine direction stretching ratio is preferably 2.0 times, more preferably 2.5 times, even more preferably 2.8 times, even more preferably 3.0 times, even more preferably 3.2 times, and most preferably 3.5 times. From the viewpoint of film passability in transverse stretching in biaxial stretching, the upper limit of the longitudinal stretching ratio is preferably 6.0 times, more preferably 5.0 times, even more preferably 4.0 times, still more preferably 3.5 times, even more preferably 3.2 times, and most preferably 3.0 times. The preferred range of the longitudinal stretching ratio can be arbitrarily selected and combined as long as the lower limit and the upper limit are the same or not reversed.

[0030] The heating method used here may be a method using a heated roll or a method using a non-contact heating medium, or a combination of these. In this case, the film temperature is preferably in the range of (Tg - 10°C) to (Tg + 50°C). More preferably, it is (Tg - 5°C) to (Tg + 40°C), and even more preferably, it is (Tg - 0°C) to (Tg + 30°C). The upper limit is more preferably (Tg + 20°C), even more preferably (Tg + 15°C), and particularly preferably (Tg + 12°C). Furthermore, from the viewpoint of film passability in the subsequent transverse stretching, the crystallinity of the film at the time of longitudinal uniaxial stretching is preferably in the range of 20% to 50%. A crystallinity of 25% to 45% is more preferable. If the crystallinity is not within the appropriate range, there is a possibility that the film will not be uniformly stretched in the width direction during the subsequent transverse stretching, or that film passability will be impaired at the transverse stretching temperature required to eliminate crazes within the film, as described below.

[0031] Since PLA has a lower crystallization temperature associated with orientation than PET, when stretched using heated rolls between rolls, at high temperatures (e.g., roll temperatures of 70°C or higher), mesophase orientation increases as crystallization progresses during stretching, potentially resulting in high haze. Therefore, it is preferable to shorten the time the film is exposed to high temperatures during longitudinal uniaxial stretching. Specific methods include, for example, setting the temperature before the final roll on the slower speed side lower and increasing the temperature of the final roll, or preheating with the rolls and then concentrating heating on the stretching point using an infrared heater or the like. Even when an infrared heater is used, because the temperature of the infrared heater tends to rise easily, it is preferable to adjust the output so that the temperature does not exceed the appropriate temperature.

[0032] The longitudinally uniaxially stretched film is then introduced into a tenter and preferably stretched 1.1 to 10 times in the width direction at a temperature of (Tg - 10°C) to Tm or lower. The transverse stretching temperature is more preferably in the range of (Tg - 0°C) to (Tg + 30°C), even more preferably (Tg + 10°C) to (Tg + 40°C), even more preferably (Tg + 20°C) to (Tg + 50°C), and most preferably (Tg + 30°C) to (Tg + 60°C). The stretching ratio is more preferably in the range of 3.0 to 6.0, even more preferably 3.5 to 5.5, and even more preferably 4.0 to 5.0. In the present invention, the mesophase orientation is controlled and film permeability is ensured by balancing the crystallinity, temperature, and stretching ratio during the sequential biaxial stretching process, thereby suppressing the occurrence of crazes, i.e., internal haze. It is particularly preferable to set the stretching temperature in the width direction to a range of (Tg+30°C) to (Tg+60°C) and the stretching ratio to 4.0 to 5.0 times.

[0033] In these transverse stretching steps, it is necessary to consider the progress of crystallization during the preheating process in the tenter and the balance between the temperature and the progress of crystallization and stress during the stretching process. If the temperature is low, the mesophase around the crystals formed during longitudinal stretching tends to become highly oriented, possibly because the mesophase does not fully dissolve. On the other hand, if the temperature is too high, crystallization progresses too quickly, resulting in an unbalanced state. Furthermore, since highly oriented crystallization progresses during stretching, the mesophase around the crystals also becomes highly oriented, which may make the film more susceptible to breakage. Specifically, for example, to prevent crystallization from progressing during preheating, it is preferable to set the preheating temperature at a low temperature of 80°C or less and gradually increase the temperature (e.g., 80°C or higher) as stretching progresses. This method reduces the stress on the mesophase and suppresses the orientation parameter. Furthermore, the relationship with the crystallinity at the time of longitudinal uniaxial stretching must also be considered. If the crystallinity becomes high during longitudinal uniaxial stretching, it is preferable to increase the transverse stretching temperature (e.g., 90°C or higher). Furthermore, the relationship between the stretch ratio and the transverse stretching ratio must also be taken into consideration, and since a high stretch ratio tends to increase the stress applied to the mesophase, it is preferable to use a higher stretching temperature. For example, when the stretch ratio exceeds 4.0, the stretching temperature is preferably 100°C or higher.

[0034] Furthermore, after the stretching is completed, in order to reduce the thermal shrinkage of the film, it is preferable to carry out a heat setting process within 30 seconds, preferably within 10 seconds, followed by a longitudinal relaxation treatment and a transverse relaxation treatment of 0.5 to 10%. These relaxation treatments result in a film with a reduced thermal shrinkage. A laminated film (such as an adhesive tape) using the obtained film (biaxially oriented polylactic acid film) as a substrate film and provided with an adhesive layer suppresses melting and deformation even under high-temperature conditions, such as 150°C, and can be satisfactorily used in applications requiring heat resistance.

[0035] The heat setting temperature is preferably in the range of 90 to 180°C. The lower limit of the heat setting temperature is more preferably 110°C, even more preferably 120°C, and particularly preferably 130°C. The lower limit of the heat setting temperature is more preferably 170°C, and particularly preferably 160°C. By setting the temperature in the above range, oriented crystallization can be promoted while alleviating excessive orientation distortion, making it easier to maintain the mesophase orientation within an appropriate range. This is also preferable because it improves the dimensional stability of the film due to heat and suppresses the phenomenon of heat-induced hole formation in the film. Increasing the heat setting temperature can produce a film with a reduced heat shrinkage rate. A laminated film (such as an adhesive tape) using the obtained film (biaxially oriented polylactic acid film) as a substrate film and provided with an adhesive layer suppresses melting and deformation even at high temperatures, such as 150°C, and can be fully used in applications requiring heat resistance.

[0036] If the film permeability and the suppression of crazes inside the film cannot be reproduced due to the temperature range of each zone in the tenter in the transverse stretching process described above, it is possible to adjust the air speed in each zone, and if the film heating is insufficient, it is preferable to increase the air speed.

[0037] (Physical properties of biaxially oriented polylactic acid film) The thickness of the biaxially oriented polylactic acid film of the present invention is preferably 2 μm or more and 500 μm or less, more preferably 15 μm or more and 400 μm or less, and even more preferably 20 μm or more and 250 μm or less. When the thickness of the biaxially oriented polylactic acid film is 2 μm or more, the biaxially oriented polylactic acid film has a minimum rigidity and is easy to handle. Furthermore, when the thickness of the biaxially oriented polylactic acid film is 500 μm or less, the transportability of the film when transported with multiple rolls and the handleability of the produced film are improved, making it easier to handle.

[0038] Mesophase orientation parameter of biaxially oriented polylactic acid film (757 cm -１ / 2996cm -１The upper limit of the mesophase orientation parameter (peak intensity ratio of the mesophase orientation parameter to the peak intensity ratio of the mesophase orientation parameter) is preferably 4.0 or less. The preferred upper limit of the mesophase orientation parameter is 3.9, more preferably 3.8, even more preferably 3.7, and most preferably 3.6. A mesophase orientation parameter of 4.0 or less is preferable because excessive orientation can be suppressed, thereby providing sufficient film transparency and suppressing crazes and internal haze caused by transparency. The mesophase orientation parameter is preferably 3.0 or more, more preferably 3.2 or more, even more preferably 3.4 or more, and particularly preferably 3.5 or more. By setting the mesophase orientation parameter to the above or higher, it becomes easier to obtain the strength required for a biaxially stretched film.

[0039] The internal haze of the biaxially oriented polylactic acid film is preferably 6% or less. The upper limit of the internal haze is more preferably 3%, even more preferably 2%, and particularly preferably 1%, and the upper limit is preferably 0.8%, 0.5%, and 0.1%, in that order. An internal haze of 6% or less is preferable because the film has sufficient transparency and can be used for optical applications and industrial components such as release casting paper. Furthermore, suppression of internal haze = suppression of craze, which is preferable because it can suppress cracking and tearing during the film processing process.

[0040] The breaking stress in the width direction of the biaxially oriented polylactic acid film is preferably 100 MPa or more, and the ratio of the breaking stress in the longitudinal direction (longitudinal direction) to the width direction is preferably 0.7 or less. The preferable lower limit of the breaking stress in the width direction is 100 MPa, more preferably 150 MPa, even more preferably 200 MPa, and even more preferably 230 MPa. A breaking stress in the width direction of 100 MPa or more is preferable because it provides sufficient mechanical strength to the film and prevents problems such as elongation and displacement during the film processing process. Considering manufacturing considerations, the upper limit of the breaking stress in the width direction is considered to be 1000 MPa.

[0041] The lower limit of the ratio of the breaking stress in the longitudinal direction to the breaking stress in the width direction is preferably 0.3, more preferably 0.33, and even more preferably 0.35. A ratio of 0.7 or less is preferred in terms of transparency.

[0042] The breaking stress in the longitudinal direction is preferably controlled to satisfy the above ratio, specifically, preferably 50 to 200 MPa, more preferably 60 to 170 MPa, even more preferably 65 to 150 MPa, and still more preferably 70 to 130 MPa. Controlling the breaking stress in the longitudinal direction within the above range is preferable from the viewpoint of stable film formation.

[0043] The tensile modulus in the width direction of the biaxially oriented polylactic acid film is preferably 2.0 GPa or more. The preferred lower limit of the tensile modulus is 3.0 GPa, more preferably 3.5 GPa, even more preferably 4.0 GPa, and even more preferably 4.5 GPa. A tensile modulus in the width direction of 4.0 GPa or more is preferable because the film has sufficient rigidity and can suppress the occurrence of wrinkles and warping of the film. In consideration of manufacturing, the upper limit of the tensile modulus in the width direction is considered to be 10.0 GPa.

[0044] The tensile modulus of elasticity in the longitudinal direction of the polylactic acid film is preferably 1.5 to 3 GPa. The tensile modulus of elasticity in the longitudinal direction is preferably 1.6 to 2.8 GPa, more preferably 1.7 to 2.6 GPa, and even more preferably 1.8 to 2.5 GPa. Controlling the tensile modulus of elasticity in the longitudinal direction within the above range is preferred from the viewpoint of stable film formation.

[0045] In biaxially oriented polylactic acid films, when heated at 150°C for 30 minutes, the heat shrinkage in the longitudinal direction (longitudinal direction) is preferably 10.0% or less. When heated at 150°C for 30 minutes, the upper limit of the heat shrinkage in the longitudinal direction is preferably 8.0% or less, more preferably 5.0% or less, even more preferably 4.0% or less, even more preferably 3.0% or less, particularly preferably 2.0% or less, and most preferably 1.0% or less. A small heat shrinkage in the longitudinal direction facilitates processing such as coating, and can suppress poor appearance due to deformation of the film under high heat. A low heat shrinkage in the longitudinal direction is preferable, but from a manufacturing standpoint, 0.01% is considered to be the lower limit.

[0046] Furthermore, when the biaxially oriented polylactic acid film is heated at 150°C for 30 minutes, the heat shrinkage in the width direction is preferably 0 to 15%. The heat shrinkage in the width direction is preferably 12% or less, more preferably 10% or less, even more preferably 7% or less, and even more preferably 5% or less. The heat shrinkage in the width direction may be 0.1% or more, 0.5% or more, or 1% or more. Controlling the heat shrinkage in the width direction within the above range is preferable from the viewpoint of processability.

[0047] The surface of the biaxially oriented polylactic acid film of the present invention is preferably smooth and has low haze. A low haze is particularly preferable when the film is used as a release film for producing ceramic green sheets or for optical purposes. The internal haze is preferably 6% or less, more preferably 3% or less, more preferably 2% or less, and most preferably 1% or less. The lower limit of the haze is the better, but it may be 0.1% or more, or even 0.3% or more. For the purpose of reducing haze, it is preferable to minimize the unevenness of the film surface. However, from the viewpoint of ease of handling with respect to a rotating roll, it is preferable to form a certain degree of unevenness on at least one surface to provide a certain degree of slipperiness.

[0048] The crystallinity of the biaxially oriented polylactic acid film is preferably 40% to 90%, more preferably 50% to 85%, and even more preferably 55% to 80%. A crystallinity in the range of 40% to 90% is preferable because it improves strength and provides a high elastic modulus.

[0049] Furthermore, when a smooth release layer or the like is formed on the surface of a biaxially oriented polylactic acid film, it is preferable that at least one surface of the polylactic acid film is also smooth. A smooth surface of a polylactic acid film preferably has an arithmetic mean roughness (Sa) of 10 nm or less and a maximum protrusion height (P) of 200 nm or less. Furthermore, a surface arithmetic mean roughness of 10 nm or less and a maximum protrusion height of 150 nm or less is more preferable, a surface arithmetic mean roughness of 10 nm or less and a maximum protrusion height of 120 nm or less is even more preferable, and a surface arithmetic mean roughness of 8 nm or less and a maximum protrusion height of 120 nm or less is even more preferable. If the surface arithmetic mean roughness is 10 nm or less and a maximum protrusion height is 200 nm or less, the surface of a release layer or the like formed on the surface can be smoothed to the same degree. The arithmetic mean roughness (Sa) of the surface of the polylactic acid film may be 0.1 nm or more, or may be 0.3 nm or more. Furthermore, the maximum protrusion height (P) on the surface may be 1 nm or more, or may be 3 nm or more.

[0050] (Laminate Film) The biaxially oriented polylactic acid film of the present invention can be used as a substrate film in the following laminate film embodiments: In order to improve the peel strength of the laminate film, the surface of the substrate film may be subjected to corona treatment, plasma treatment, etc.

[0051] One embodiment of the laminate film of the present invention includes a substrate film containing a biaxially oriented polylactic acid film and a resin layer on at least one side of the substrate film (however, the resin layer does not include the release layer of the laminate film (2) below or the pressure-sensitive adhesive layer of the laminate film (3) below). Hereinafter, this will be referred to as laminate film (1). Another embodiment of the laminate film of the present invention includes a substrate film containing a biaxially oriented polylactic acid film and a release layer on at least one side of the substrate film. Hereinafter, this will be referred to as laminate film (2). Another embodiment of the laminate film of the present invention includes a substrate film containing a biaxially oriented polylactic acid film and a pressure-sensitive adhesive layer on at least one side of the substrate film. Hereinafter, this will be referred to as laminate film (3).

[0052] (Laminated film (1)) The resin layer of the laminated film (1) can be provided on one side or both sides of the base film, and when provided on both sides, the resin layer may be the same or different. Different resin layers mean resin layers that are different in at least one of composition and thickness, and when different, the resin layers are preferably resin layers with different compositions.

[0053] (Resin Layer) Examples of the resin layer include functional layers such as a polyester layer other than polylactic acid, an easy-adhesion layer, an antistatic layer, an easy-slip layer, a barrier layer, an ultraviolet absorbing layer, an antibacterial layer, and an antifouling layer. The easy-adhesion layer can be provided to improve the adhesion between the biaxially oriented polylactic acid film and an adhesive layer or a hard coat layer. Furthermore, the easy-slip layer can be provided by adding particles to the coat layer to form irregularities in order to ensure a certain degree of slipperiness for neatly winding the biaxially oriented polylactic acid film. The resin layer can be formed in one layer or in two or more layers.

[0054] The resin layer is preferably formed from a resin layer-forming material containing an aqueous resin. The resin layer-forming material contains an aqueous resin, and more preferably contains lubricant particles. The presence of the resin layer (e.g., easy-adhesion layer, easy-slip layer) improves the adhesion of the laminated film (1) and further imparts easy slip during film roll production while maintaining the high transparency that is a characteristic of the biaxially oriented polylactic acid film of the present invention, depending on the function of the resin layer. Note that the aqueous resin refers to a water-soluble or water-dispersible resin and is a resin that can be used as an aqueous coating liquid. The aqueous resin preferably has a hydrophilic group such as a carboxylic acid group, a sulfonic acid group, a carboxylate group, a sulfonate group, or a hydroxyl group.

[0055] The aqueous resin is not particularly limited, but from the viewpoint of controlling the surface free energy γs of the resin layer described below, it is preferable that the resin contains at least one of polyester resin, polyurethane resin, or acrylic resin as the main component. Here, "main component" refers to a component that accounts for 50% by mass or more of the solid components constituting the resin layer. The forming material (coating liquid) used to form the resin layer of the present invention is preferably an aqueous coating liquid containing at least one of water-soluble or water-dispersible copolymer polyester resin, acrylic resin, and polyurethane resin. The aqueous resin is also preferable from the viewpoint of preventing the antistatic agent described below from falling off when the resin layer contains the antistatic agent.

[0056] The aqueous resin of the present invention may contain two or more types to improve adhesiveness. For example, to achieve both adhesion and moist heat resistance, two or more different resins, such as a combination of a polyester resin and a polyurethane resin, a polyester resin and an acrylic resin, or a polyurethane resin and an acrylic resin, may be used. Furthermore, two or more polyester resins with different glass transition temperatures may be used.

[0057] In the present invention, a crosslinking agent may be contained in the resin layer-forming material to form a crosslinked structure in the resin layer. By containing a crosslinking agent, it becomes possible to further improve adhesion under high temperature and high humidity conditions. Examples of crosslinking agents include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based crosslinkers. Among these, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based crosslinkers are preferred in terms of the stability of the coating liquid over time and the effect of improving adhesion under high temperature and high humidity treatment. Furthermore, a catalyst or the like may be used as needed to promote the crosslinking reaction.

[0058] The content of the crosslinking agent in the resin layer-forming material is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 30% by mass or less, based on the total solid components. By making the content above this range, the strength of the resin in the resin layer and the adhesion under high temperature and high humidity conditions can be increased, and by making the content below this range, it becomes easier to suppress a decrease in the flexibility of the resin in the resin layer and a decrease in adhesion under normal temperature and high temperature and high humidity conditions.

[0059] The lubricant particles may be either inorganic particles or organic particles, and may be used in combination. The inorganic particles are not particularly limited, and examples thereof include silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, titanium dioxide, zirconium dioxide, tin oxide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, hydrated halloysite, magnesium carbonate, and magnesium hydroxide.

[0060] The organic particles are not particularly limited, but examples thereof include particles of polystyrene, melamine resin, acrylic, acrylic-styrene, silicone, benzoguanamine resin, benzoguanamine-formaldehyde condensation resin, polycarbonate, polyethylene, etc., and it is preferable that the particles of these resins are three-dimensionally crosslinked.

[0061] The inclusion of lubricant particles can impart lubricity, thereby suppressing the occurrence of wrinkles when the film is wound up during the film manufacturing process, etc., and blocking, in which films stick to each other due to tightening over time when wound film rolls are stored for long periods of time.

[0062] The average particle size of the lubricant particles is not particularly limited, but from the viewpoint of maintaining the transparency of the film, the average particle size of the lubricant particles is preferably 1 to 500 nm, and more preferably 1 to 100 nm. The average particle size is measured using a Coulter Counter (Multisizer II, manufactured by Beckman Coulter) after dispersing the particles in a solvent that does not swell the particles. The lubricant particles may be two or more types of particles with different average particle sizes, and may be any of a combination of inorganic particles, a combination of organic particles, or a combination of inorganic particles and organic particles.

[0063] The content of the lubricant particles in the resin layer is preferably 0.1% by mass or more and 30% by mass or less, and more preferably 1% by mass or more and 20% by mass or less, of the total solid content of the resin layer-forming material. By making it more than this amount, sufficient blocking resistance can be easily obtained and scratch resistance can be easily improved. By making it less than this amount, the transparency of the resin layer and the coating strength can be easily improved.

[0064] The resin layer-forming material may contain a surfactant to improve leveling during coating and to defoam the coating solution. The surfactant may be cationic, anionic, or nonionic, but silicone, acetylene glycol, or fluorine-based surfactants are preferred. These surfactants are preferably contained in the resin layer to an extent that does not impair adhesion with other functional layers, pressure-sensitive adhesive layers, or release layers laminated on the resin layer.

[0065] In order to impart other functionality to the resin layer, various additives may be contained in the resin layer-forming material to the extent that the adhesiveness with other functional layers, pressure-sensitive adhesive layers, and release layers is not impaired. Examples of the additives include fluorescent dyes, fluorescent brighteners, plasticizers, ultraviolet absorbers, pigment dispersants, foam inhibitors, antifoaming agents, preservatives, and antistatic agents.

[0066] Polylactic acid films have high electrical insulation properties and are therefore prone to static buildup, which can lead to problems such as repelling during coating or printing, and films being fed one over the other when processed sheet by sheet. To prevent this, it is preferable that the resin layer contains an antistatic agent as an additive. The antistatic agent is not particularly limited, but by including an antistatic agent in the resin layer, static buildup during film transport during printing can be reduced, and deterioration in processability due to dust adsorption and film-to-film adhesion caused by frictional charging can be suppressed.

[0067] Antistatic agents include ionic conductive types and conductive polymer types, and those that can suppress migration to other objects or the back surface of the film itself that come into contact with them are preferred. For example, ionic conductive types include nonionic types whose functional groups are sorbitan, ether, ester, sorbitol, glucose, etc.; cationic types such as quaternary ammonium salt, quaternary ammonium resin, imidazoline, Arcobel, and Solomin A; anionic types such as alkyl sulfate, alkyl phosphate, phosphate ester, and sulfate ester; and amphoteric surfactant types such as betaine, amino acid, and amino sulfate, or polymer types. Since aqueous resins used in resin layers are generally used as aqueous dispersions, anionic antistatic agents are preferred in terms of dispersion stability in the coating liquid.

[0068] As the conductive polymer type, a π-electron conjugated conductive polymer can be suitably used. Unlike the ionic conductive type described above, a π-electron conjugated conductive polymer is suitable because it can exhibit stable and effective antistatic properties even under low humidity conditions. As the π-electron conjugated conductive polymer, the repeating unit is preferably aniline and / or a derivative thereof, pyrrole and / or a derivative thereof, isothianaphthene and / or a derivative thereof, acetylene and / or a derivative thereof, thiophene and / or a derivative thereof, or the like. Among these, thiophene and / or a derivative thereof is particularly preferred because of its low coloration.

[0069] The content of the antistatic agent contained in the resin layer is preferably 5% by mass or more and 45% by mass or less relative to the aqueous resin of the resin layer-forming material. The antistatic agent reduces the charge on the resin layer surface and can suppress problems during printing. The content of the antistatic agent is more preferably 7% by mass or more, and even more preferably 8% by mass or more. The upper limit may be 40% by mass or less. By making the content of the antistatic agent above the above range, the required antistatic properties can be achieved and printing problems such as poor appearance can be suppressed. Furthermore, by making the content of the antistatic agent below the above range, the wettability of the resin layer surface can be appropriately controlled and offset and blocking in a film roll due to excessive addition can be suppressed. The antistatic agent is contained in the resin layer in an amount within the above range.

[0070] The antistatic property of the laminated film (1') having a resin layer containing an antistatic agent laminated thereon is such that the surface resistivity of the resin layer surface is 1.0 x 10 １４ It is preferably Ω / sq or less, and 1.0×10 １３ Ω / sq or less is more preferable, and 1.0 × 10 １２ By setting the surface resistivity at or below this level, it is possible to reduce charging during film transport during printing processing, and to suppress deterioration of processability due to dust adsorption and film adhesion due to frictional charging. The surface resistivity of the resin layer surface is preferably 1.0 × 10 ９ It is preferably 5.0×10 Ω / sq or more. ９ More preferably, Ω / sq or more, and 1.0×10 １０ By making it equal to or greater than the above range, bleeding out of the antistatic agent can be made less likely to occur.

[0071] In the present invention, a method for providing a resin layer on a substrate film having a biaxially oriented polylactic acid film includes coating a resin layer-forming material (coating liquid) containing a solvent, particles, and a resin onto the substrate film, followed by drying. From the viewpoint of environmental concerns, the solvent is preferably water or a mixture of water and a water-soluble organic solvent, and the water solvent in the coating liquid is preferably 50 to 95% by mass, and particularly preferably 60 to 90% by mass.

[0072] In the present invention, the solid content concentration in the coating liquid is preferably 0.5 to 35% by mass, and particularly preferably 1.0 to 15% by mass.

[0073] The coating solution can be applied to the substrate film by any known method, such as reverse roll coating, gravure coating, kiss coating, die coating, roll brushing, spray coating, air knife coating, wire bar coating, pipe doctor coating, impregnation coating, curtain coating, etc. These methods can be used alone or in combination.

[0074] The method for forming the resin layer is not particularly limited, and conventional methods such as coating can be used. Among the coating methods, preferred are coating after the production of a biaxially stretched film (offline coating) and coating during the biaxially stretched film production process (inline coating). Inline coating is preferred because it improves adhesion between the substrate film and the resin layer and minimizes deterioration of the substrate film's mechanical properties and heat wrinkles during production. In the case of inline coating, which is performed during the production of a biaxially oriented polylactic acid film, the drying and heat treatment conditions during coating vary depending on the coating thickness and equipment conditions. However, it is preferable to feed the film into a transverse stretching process immediately after coating and dry it in the preheating zone or stretching zone of the stretching process. In such cases, a temperature of approximately 50 to 120°C is typically preferred. Furthermore, the heat treatment process after stretching depends on the required mechanical properties of the substrate film and the equipment conditions, but heat treatment at a temperature of 130°C or higher is preferred from the perspective of improving the adhesive strength between the substrate film and the resin layer. As the resin layer, an easy-adhesion layer for improving adhesion, an easy-slip layer for providing slipperiness, etc. are preferably formed by in-line coating.

[0075] In the in-line coating method, the resin layer is formed by applying the coating liquid to an unstretched or uniaxially stretched polylactic acid film, drying the film, stretching the film at least uniaxially, and then heat-treating the film.

[0076] In addition, when the resin layer is provided as an in-line coating layer during the stretching film-forming process when producing a biaxially oriented polylactic acid film, the in-line coating layer is already laminated when the biaxially oriented polylactic acid film is produced.

[0077] The thickness of the resin layer of the present invention is preferably 1 μm or less. When the resin layer is formed by an in-line coating method, the thickness of the resin layer obtained in the end is preferably 20 nm or more and 500 nm or less, more preferably 30 nm or more and 300 nm or less, and even more preferably 30 nm or more and 200 nm or less. By making the thickness of the resin layer 20 nm or more, it becomes easier to obtain a high effect on the lubricity required in the present invention. On the other hand, by making the thickness of the resin layer 500 nm or less, it becomes easier to suppress an increase in haze and a decrease in transparency.

[0078] In the present invention, the surface free energy γs of the final resin layer is preferably 40 mN / m or more. Since polylactic acid films have poorer wettability than general polyester films, a surface free energy γs of 40 mN / m or more improves the coatability of the aqueous resin, making it easier to achieve a uniform thickness when the resin layer is laminated, and making it easier to prevent coating unevenness and cissing, which can lead to poor coating appearance. It also prevents the uneven distribution of lubricant particles contained in the resin layer, which can prevent partial reduction in lubrication and reduce the occurrence of wrinkles when the film is wound up. Furthermore, the surface free energy γs is preferably as high as possible within manufacturing limits. However, since a higher surface free energy γs increases hydrophilicity and makes the resin layer surface more susceptible to moisture absorption, it is preferably 80 mN / m or less. The surface free energy γs may be 70 mN / m or less, 60 mN / m or less, 55 mN / m or less, or 50 mN / m or less.

[0079] The static friction coefficient and dynamic friction coefficient of the laminate film (1) of the present invention are both preferably 0.40 or more and 0.70 or less. If it is less than 0.40, winding slippage is likely to occur when the film roll is transported. On the other hand, if it exceeds 0.70, the lubricity decreases, and wrinkles are likely to occur when the film is wound up. The static friction coefficient and dynamic friction coefficient are more preferably 0.68 or less, and even more preferably 0.66 or less. The static friction coefficient and dynamic friction coefficient are values ​​measured by overlapping one side of the laminate film (1) with the other side.

[0080] (Laminate Film (2)) The release layer of the laminate film (2) can be provided on one or both sides of the base film. The release layer is preferably provided on the outermost surface of the laminate film (2). The embodiment of the laminate film (2) having the release layer can be applied together with the embodiment of the laminate film (1). That is, the biaxially oriented polylactic acid film of the present invention can be used as the base film of the laminate film (2) having the release layer, and the laminate film (1) can also be used. When a release layer is applied to the embodiment of the laminate film (1), the release layer may be provided on the resin layer surface, or may be provided directly on the base film including the biaxially oriented polylactic acid film without the resin layer. When the release layer is provided on one side of the base film, it is preferable that the surface of the base film opposite the release layer be a resin layer. It is preferable that the release layer is directly laminated on one side of the base film and a resin layer is provided on the other side.

[0081] (Release Layer) The release layer is formed from a release layer-forming material, and the resin constituting the release component is not particularly limited, and silicone resin, fluororesin, alkyd resin, various waxes, aliphatic olefin, etc. can be used, and each resin can be used alone or in combination of two or more types. It is preferable that the release layer contains a silicone release component such as silicone resin or silicone oil.

[0082] For example, a silicone resin is a resin having a silicone structure within the molecule, and examples thereof include curable silicones, silicone graft resins, and modified silicone resins such as alkyl-modified silicones. However, from the viewpoint of migration, it is preferable to use a reactive curable silicone resin. Examples of reactive curable silicone resins that can be used include addition reaction-based resins, condensation reaction-based resins, and ultraviolet or electron beam curable resins. Low-temperature curable addition reaction-based resins that can be processed at low temperatures, and ultraviolet or electron beam curable resins are more preferable. The use of these silicone resins allows for low-temperature processing when coating polyester films. Therefore, heat damage to the polyester film during processing is reduced, resulting in a polyester film with high flatness. This also reduces defects such as pinholes when producing thin sheets such as ceramic green sheets.

[0083] Examples of silicone resins that use addition reactions include those that are cured by reacting polydimethylsiloxane, which has vinyl groups introduced into the terminals or side chains, with hydrogen siloxane using a platinum catalyst. In this case, it is more preferable to use a resin that can be cured within 30 seconds at 120°C, as this allows for processing at low temperatures. Examples include low-temperature addition cure types (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC755, LTC760A, etc.) and thermal UV cure types (LTC851, BY24-510, BY24-561, BY24-562, etc.) manufactured by Dow-Toray Industries, and solvent addition + UV cure types (X62-5040, X62-5065, X62-5072T, KS5508, etc.) and dual cure cure types (X62-2835, X62-2834, X62-1980, etc.) manufactured by Shin-Etsu Chemical Co., Ltd.

[0084] An example of a condensation reaction silicone resin is one in which a three-dimensional crosslinked structure is formed by condensing a polydimethylsiloxane having an OH group at its terminal with a polydimethylsiloxane having an H group at its terminal using an organotin catalyst.

[0085] Examples of UV-curable silicone resins include, for example, the most basic type that utilizes the same radical reaction as normal silicone rubber crosslinking, those that introduce unsaturated groups to cause photocuring, those that use UV light to decompose onium salts to generate strong acids that then cleave epoxy groups to cause crosslinking, and those that crosslink via an addition reaction of thiol to vinyl siloxane. Electron beams can also be used instead of UV light. Electron beams have stronger energy than UV light, making it possible to carry out a radical-based crosslinking reaction without using an initiator as in UV curing. Examples of resins that can be used include UV-curable silicones manufactured by Shin-Etsu Chemical Co., Ltd. (X62-7028A / B, X62-7052, X62-7205, X62-7622, ​​X62-7629, X62-7660, etc.), UV-curable silicones manufactured by Momentive Performance Materials (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.), and UV-curable silicones manufactured by Arakawa Chemical Industries, Ltd. (SilicoLease UV POLY200, POLY215, POLY201, KF-UV265AM, etc.).

[0086] The ultraviolet-curable silicone resin may be an acrylate-modified or glycidoxy-modified polydimethylsiloxane, etc. Good release properties can also be achieved by mixing such modified polydimethylsiloxane with a polyfunctional acrylate resin or epoxy resin, etc., and using the mixture in the presence of an initiator.

[0087] Other suitable examples of resins used in the release component of the release layer molding material include alkyd resins and acrylic resins having long-chain alkyl groups, such as stearyl-modified and lauryl-modified, or alkyd-based resins, acrylic-based resins, and olefin-based resins obtained by reactions such as methylated melamine. When molding sheets for use in electronic components, etc., release agents that do not contain silicone are also preferred.

[0088] Examples of the aminoalkyd resins and aminoacrylic resins obtained by the reaction of methylated melamine include the Tesfine series manufactured by Showa Denko Materials Co., Ltd.

[0089] When the above resin is used as the release component of the release layer molding material of the present invention, one type may be used or two or more types may be mixed. When two or more types are mixed, two or more types of silicone-based resins may be used, and it is also preferable to mix multiple different resin types, such as a binder resin and a silicone-based resin.

[0090] The laminated film (2) of the present invention can be suitably used as a release film, and in particular, when used as a release film when molding a thin film sheet such as a ceramic green sheet, it is preferable that the release layer does not deform when peeled off, so it is preferable that the release layer is crosslinked and cured. Therefore, it is also preferable that the release layer contains a binder component, a crosslinking agent, etc. in addition to the silicone-based release agent.

[0091] The binder component contained in the release layer molding material of the present invention is preferably a crosslinked component that can be crosslinked to increase the crosslink density of the release layer and improve the durability and solvent resistance of the release layer. Therefore, the binder component is preferably formed by reacting a resin having a reactive functional group with a crosslinking agent. It is also preferable that either the reactive functional group or the crosslinking agent is self-crosslinked alone. However, the present invention does not exclude an embodiment in which the binder component consists only of a resin having a reactive functional group or a crosslinking agent.

[0092] Suitable examples of resins having a reactive functional group include polyester resins, acrylic resins, polyurethane resins, polyolefin resins, etc. These resins preferably have at least one reactive functional group selected from the group consisting of carboxyl groups, hydroxyl groups, epoxy groups, amino groups, etc.

[0093] It is also preferable that the release layer molding material of the present invention contains a crosslinking agent. Examples of preferred crosslinking agents include melamine-based, isocyanate-based, carbodiimide-based, oxazoline-based, and epoxy-based crosslinking agents. One type of crosslinking agent may be used alone, or two or more types may be used in combination. Particularly preferred is a crosslinking agent that reacts with the reactive functional group introduced into the binder component.

[0094] The release layer molding material of the present invention may contain particles having a particle size of 1 μm or less, but from the viewpoint of preventing pinholes, it is preferable that it does not substantially contain particles or other particles that form protrusions.

[0095] In order to adjust the release force of the release layer, additives such as a light release additive or a heavy release additive, or additives such as an adhesion improver or an antistatic agent may be added to the release layer molding material of the present invention. In order to improve adhesion to the substrate layer, it is also preferable to perform pretreatment such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment on the surface of the polylactic acid film before providing the release coating layer.

[0096] In the present invention, the thickness of the release layer may be set depending on the intended use and is not particularly limited, but is preferably in the range of 0.005 to 2.0 μm after curing. A release layer thickness of 0.005 μm or more is preferable because release performance is maintained. Furthermore, a release layer thickness of 2.0 μm or less is preferable because the curing time is not too long and there is no risk of uneven thickness of the sheet due to a decrease in the flatness of the release film. Furthermore, because the curing time is not too long, there is no risk of the resin constituting the release layer agglomerating and forming protrusions, which is preferable because pinhole defects in the sheet are less likely to occur.

[0097] The outer surface of the film on which the release layer is formed (i.e., the outer surface of the release layer) is preferably flat so as not to cause defects in the sheet to be coated and molded on the outer surface of the film. The arithmetic mean roughness (Sa) of the release layer surface is preferably 10 nm or less and the maximum protrusion height (P) is preferably 200 nm or less. Furthermore, the arithmetic mean roughness of the release layer surface is more preferably 10 nm or less and the maximum protrusion height is 100 nm or less, and even more preferably the arithmetic mean roughness of the release layer surface is 10 nm or less and the maximum protrusion height is 30 nm or less. If the arithmetic mean roughness of the release layer surface is 10 nm or less and the maximum protrusion height is 200 nm or less, defects such as pinholes do not occur during sheet formation, and the yield is good, which is preferable. It can be said that the smaller the arithmetic mean roughness (Sa) of the release layer surface, the better, but it may be 0.1 nm or more, or 0.3 nm or more. It can be said that the smaller the maximum protrusion height (P), the more preferable it is, but it may be 1 nm or more, or 3 nm or more.

[0098] The lower limit of the surface free energy of the release layer of the present invention is 8 mJ / m ２ More preferably, it is 10 mJ / m or more. ２ or more, and 12 mJ / m ２ More preferably, it is 8 mJ / m or more. ２ If the thickness is more than this, repelling or the like is less likely to occur when the sheet dissolving solution is applied, which is preferable.

[0099] The upper limit of the surface free energy of the release layer of the present invention is 45 mJ / m ２ It is preferably 40 mJ / m or less. More preferably, it is 40 mJ / m ２ less than 35 mJ / m ２ More preferably, it is 45 mJ / m ２ If it is less than this, the releasability of the molded sheet is good, which is preferable.

[0100] In the present invention, the method for forming the release layer is not particularly limited, and a method is used in which a release layer-forming material (coating liquid) in which the resin constituting the release component is dissolved or dispersed is spread on one side of a substrate film by coating or the like, the solvent is removed by drying, and then the resulting material is heated and dried, heat-cured, or cured with ultraviolet light. In this case, the drying temperature during solvent drying and heat-curing is preferably 180°C or less, more preferably 150°C or less, and most preferably 120°C or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less. At 180°C or less, the flatness of the film is maintained and there is little risk of uneven thickness of the sheet, which is preferable. At 120°C or less, the film can be processed without impairing the flatness of the film, and there is a further reduction in the risk of uneven thickness of the sheet, which is particularly preferable.

[0101] In the present invention, the surface tension of the coating liquid when applying the release layer-forming material (coating liquid) to the substrate film is not particularly limited, but is preferably 30 mN / m or less. By adjusting the surface tension to the above range, the wettability after application can be improved and the unevenness of the coating film surface after drying can be reduced.

[0102] In the present invention, when the release layer-forming material (coating liquid) is applied to the substrate film, the coating liquid is not particularly limited, but it is preferable to add a solvent having a boiling point of 90° C. or higher. Adding a solvent having a boiling point of 90° C. or higher can prevent bumping during drying, level the coating film, and improve the smoothness of the coating film surface after drying. The amount of solvent added is preferably about 10 to 80% by mass of the total coating liquid.

[0103] Examples of the coating method for the coating liquid include roll coating methods such as gravure coating and reverse coating, bar coating using a wire bar, die coating, spray coating, and air knife coating.

[0104] (Release Film) The laminated film (2) having a release layer of the present invention can be used as a release film for the production or transfer of ceramic green sheets, various resin sheets, optical films, pressure sensitive adhesive sheets, adhesive sheets, etc.

[0105] The laminated film (2) having a release layer of the present invention can be used as a release film, and is particularly suitable as a release film for producing a ceramic green sheet. The same applies to the laminated film (1) having a release layer.

[0106] (Ceramic Green Sheet and Ceramic Capacitor) Generally, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. First internal electrodes and second internal electrodes are alternately provided inside the ceramic body along the thickness direction. The first internal electrodes are exposed at a first end face of the ceramic body. A first external electrode is provided on the first end face. The first internal electrode is electrically connected to the first external electrode at the first end face. The second internal electrode is exposed at a second end face of the ceramic body. A second external electrode is provided on the second end face. The second internal electrode is electrically connected to the second external electrode at the second end face.

[0107] A release film for producing ceramic green sheets is used to produce such multilayer ceramic capacitors. For example, it can be produced as follows. First, using the release film of the present invention as a carrier film, a ceramic slurry for forming a ceramic body is applied and dried. A conductive layer for forming a first or second internal electrode is printed on the applied and dried ceramic green sheet. A mother laminate is obtained by appropriately stacking and pressing ceramic green sheets, ceramic green sheets on which a conductive layer for forming a first internal electrode is printed, and ceramic green sheets on which a conductive layer for forming a second internal electrode is printed. The mother laminate is divided into multiple pieces to produce green ceramic bodies. The green ceramic bodies are fired to obtain ceramic bodies. Then, first and second external electrodes are formed to complete the multilayer ceramic capacitor.

[0108] (Laminated Film (3)) The pressure-sensitive adhesive layer of the laminated film (3) can be provided on one or both sides of the base film. The pressure-sensitive adhesive layer is preferably provided on the outermost surface of the laminated film (3). The embodiment of the laminated film (3) having the pressure-sensitive adhesive layer can be applied together with the embodiments of the laminated films (1) and (2). That is, as the base film of the laminated film (3) having the pressure-sensitive adhesive layer, the biaxially oriented polylactic acid film of the present invention can be used, and the laminated film (1) can also be used. In this case, the pressure-sensitive adhesive layer can be laminated either on the side of the resin layer or on the side of the base film on which the resin layer is not laminated, but it is preferably laminated on the side of the base film on which the resin layer is not laminated.

[0109] Furthermore, when a pressure-sensitive adhesive layer is applied to the embodiment of the laminate film (2) having the release layer, the base film may have the pressure-sensitive adhesive layer on one side thereof and the release layer on the side opposite to the side having the pressure-sensitive adhesive layer (back side). By having a release layer on the back side, even when the laminate film (3) is wound into a roll, the laminate film (3) can be smoothly unwound from the roll, making it easier to distribute the laminate as a rolled product.

[0110] A separator for protecting the adhesive layer may be provided on the adhesive layer of the laminated film (3). The separator may be any separator as long as it has releasability, and examples thereof include a substrate such as paper or film on which the above-mentioned release layer is provided. The release layer used in the separator may be any of the above-mentioned release layers. One preferred distribution form for the laminated film (3) is to laminate a separator and wind it into a roll.

[0111] (Adhesive Layer) The adhesive constituting the adhesive layer is not particularly limited, and may be one or a combination of two or more known adhesives such as rubber-based adhesives, acrylic-based adhesives, vinyl alkyl ether-based adhesives, silicone-based adhesives, polyester-based adhesives, polyamide-based adhesives, urethane-based adhesives, styrene-diene block copolymer-based adhesives, and creep property-improved adhesives obtained by blending these adhesives with a heat-melting resin having a melting point of about 200° C. or less. The adhesive may be any known adhesive such as a solvent-based adhesive, emulsion-based adhesive, hot-melt-based adhesive, energy ray-curable adhesive, or heat-peelable adhesive.

[0112] Generally, the pressure-sensitive adhesive may be a rubber-based pressure-sensitive adhesive having natural rubber or various synthetic rubbers as a base polymer; or an acrylic pressure-sensitive adhesive having an acrylic polymer (homopolymer or copolymer) containing one or more of the following as a monomer component: (meth)acrylic acid alkyl ester {note that (meth)acrylic acid alkyl ester means acrylic acid alkyl ester and / or methacrylic acid alkyl ester. In this specification, (meth) has the same meaning as above.}. In the present invention, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is particularly preferably used.

[0113] Examples of the (meth)acrylic acid alkyl ester used as a monomer component of the acrylic polymer include C1-20 alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0114] The acrylic polymer may contain, as necessary, units corresponding to other monomer components copolymerizable with the alkyl (meth)acrylate, for the purpose of modifying properties such as cohesive strength, heat resistance, and crosslinkability. Examples of such monomer components include (meth)acrylic acid esters having an aliphatic cyclic skeleton such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclohexylmethyl (meth)acrylate, and bornyl (meth)acrylate; (meth)acrylic acid esters having an aromatic carbon ring such as phenyl (meth)acrylate and benzyl (meth)acrylate; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride group-containing monomers such as maleic anhydride and itanoic anhydride; and hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate. Monomers: sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; (N-substituted) amide-containing monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide; aminoalkyl (meth)acrylate monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide;Itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide; succinimide-based monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; vinyl acetate, propionyl alcohol, etc. vinyl monomers such as vinyl acetate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; poly(meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers having a heterocycle, a halogen atom, a silicon atom, or the like, such as N-(meth)acryloylmorpholine, tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; polyfunctional monomers such as hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; olefin-based monomers such as isoprene, butadiene, and isobutylene;and vinyl ether-based monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more.

[0115] It is also preferable that the pressure-sensitive adhesive layer uses a biomass-derived raw material. Examples of biomass-derived raw materials include using a biomass-derived base polymer or a biomass-derived crosslinking agent, but it is preferable to use a biomass-derived base polymer and further preferable to use a biomass-derived crosslinking agent as well.

[0116] To make synthetic rubber biomass-derived, diene monomers such as butadiene and isoprene may be biomass-derived, or biomass-derived styrene may be used. A preferred method for making an acrylic polymer biomass-derived is to use a biomass-derived acrylic monomer as a monomer component. In the present invention, a bioacrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is particularly preferably used.

[0117] The acrylic monomer is made from (meth)acrylic acid, and the biomass-derived acrylic monomer can be produced by using biomass-derived (meth)acrylic acid as a raw material. When the biomass-derived acrylic monomer is a (meth)acrylic acid alkyl ester, there are two methods: one is to make the (meth)acrylic acid biomass-derived, and the other is to make the alcohol or the like to be reacted with the carboxyl group of the (meth)acrylic acid biomass-derived. Either method is acceptable, and it is particularly preferable to make both biomass-derived. The (meth)acrylic acid made from a biomass-derived raw material is not particularly limited. For example, acrylic acid made from a biomass-derived raw material can be produced from glycerin, a by-product of producing biodiesel fuel from vegetable oil, via acrolein. In the case of methacrylic acid, for example, a method using a microorganism capable of producing methacrylic acid from organic matter containing isobutyric acid or valine, as proposed in WO 2014 / 038216, can be used. Various alcohols are known, including methanol, ethanol, propanol, butanol, pentanol, hexanol, 2-ethylhexanol, and 2-octanol, and these can be used. Biomass-derived ethylene oxide can also be used to produce 2-hydroxyethyl (meth)acrylate. Biomass-derived (meth)acrylic acid can also be used as a copolymerization component for alkyl (meth)acrylate esters.

[0118] The acrylic polymer can be produced by known radical polymerization methods such as solution polymerization, bulk polymerization, and emulsion polymerization. The acrylic polymer may be any of a random copolymer, a block copolymer, a graft polymer, and the like. In the polymerization, a commonly used polymerization initiator and a chain transfer agent can be used.

[0119] The weight-average molecular weight of the base polymer constituting the PSA is, for example, 10,000 to 2,000,000, preferably 300,000 to 1,500,000. If the weight-average molecular weight of the base polymer is too low, the adhesiveness to the adherend is excellent, but contamination such as adhesive residue is likely to occur on the adherend, for example, when peeling by heating. On the other hand, if the weight-average molecular weight of the base polymer is too high, the adhesiveness to the adherend is likely to decrease.

[0120] In addition to the base polymer, the pressure-sensitive adhesive may contain, as necessary, appropriate additives such as a crosslinking agent (an epoxy-based crosslinking agent, an isocyanate-based crosslinking agent, a melamine-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a metal chelate compound, etc.), a crosslinking accelerator (a crosslinking catalyst), a tackifier (for example, a rosin derivative resin, a polyterpene resin, a petroleum resin, an oil-soluble phenolic resin, etc.), a thickener, a plasticizer, a filler, a foaming agent, an antioxidant, an antioxidant, an ultraviolet absorber, an antistatic agent, a surfactant, a leveling agent, a colorant, a flame retardant, a silane coupling agent, etc.

[0121] There are no particular limitations on the crosslinking agent made from biomass-derived raw materials, and for example, in the case of isocyanates, a crosslinking agent made from biomass-derived raw materials can be produced using 1,5-pentamethylene diisocyanate made from plant-derived raw materials, and this is commercially available and preferably used as Tabio® from Mitsui Chemicals, Inc. In addition, biomass-derived isophorone diisocyanate produced via biomass-derived acetone has been reported by Evonik, and biomass-derived diphenylmethane diisocyanate is also known, and these can also be used as crosslinking agents.

[0122] For example, epoxy resins such as Green Denacol® GEX-313, 512, 521, 622, 614B, and 252 are commercially available from Nagase ChemteX Corporation, and these can be used. Furthermore, melamine crosslinking agents are preferred crosslinking agents for use in combination with biomass-derived resins because they emit less carbon dioxide since melamine is synthesized using urea and carbon dioxide. Furthermore, the melamine crosslinking agent used is alkyl-etherified melamine, and those alkyl-etherified using bioaldehyde, biomethanol, biobutanol, or the like are preferably used.

[0123] A pressure-sensitive adhesive layer made from a biomass-derived raw material can be produced by reacting a (meth)acrylic acid alkyl ester made from a biomass-derived raw material with a crosslinking agent made from a biomass-derived raw material.

[0124] These pressure-sensitive adhesives are commercially available, for example, as the EKX series from Toyochem Co., Ltd., such as 20-136, -137, -139, -140, and -142, and as P-7360A, P-7360B, P-7361A, P-7361B, P-7366A, P-7366A, and P-7369 from Daido Chemical Industry Co., Ltd., and these are preferably used.

[0125] The biomass degree of the adhesive layer is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. A higher biomass degree of the adhesive layer is preferable, with the upper limit being 100%, but it may be difficult to use all additives, etc., derived from biomass. Therefore, the biomass degree of the adhesive layer may be 95% or less, or even 90% or less. The biomass degree of the adhesive can be calculated by measuring the proportion of C14 contained in the total carbon atoms in the adhesive. This biomass degree can be measured, for example, by radiocarbon (C14) measurement as specified in ASTM D6866-16 Method B (AMS). The above numerical value is calculated based on the mass of the biomass-derived component (for example, in the case of ethyl acrylate, if the acrylic acid portion is derived from fossil materials and the ethanol is derived from biomass, the ratio of -OC to the mass of the ethyl acrylate).２ H ５ However, when the composition of the PSA is not precisely known, the ratio of biomass-derived carbon to total carbon (molar ratio) may be used. In the case of a molar ratio, the biomass ratio is preferably 3.3% or more, more preferably 6.6% or more, even more preferably 13.2% or more, and particularly preferably 20% or more, with the upper limit remaining the same.

[0126] The pressure-sensitive adhesive layer can be formed by a known or conventional method. Examples include a method of applying a pressure-sensitive adhesive composition to a substrate (or to an intermediate layer, if present on the substrate), and a method of applying a pressure-sensitive adhesive composition to an appropriate separator to form a pressure-sensitive adhesive layer, and then transferring (adhering) the pressure-sensitive adhesive layer to a substrate (or to an intermediate layer, if present on the substrate). The application can be carried out using a coater, extruder, printer, or the like that is generally used for forming pressure-sensitive adhesive layers.

[0127] The thickness of the pressure-sensitive adhesive layer can be appropriately selected depending on the application, etc., and is, for example, 2 to 3000 μm, preferably about 5 to 500 μm, and may be 200 μm or less, 100 μm or less, or 50 μm or less.

[0128] The adhesive strength of the pressure-sensitive adhesive layer at 25°C (180° peel, against polyethylene terephthalate film, tensile speed 300 mm / min) can be appropriately selected depending on the application (weak adhesive type, strong adhesive type, etc.), and is, for example, 3.0 N / 20 mm or more, preferably 5.0 N / 20 mm or more, and more preferably 7.0 N / 20 mm or more, and in the case of a strong adhesive type, more preferably 10.0 N / 20 mm or more.

[0129] The laminate film (3) of the present invention may have another layer (intermediate layer) between the base film and the pressure-sensitive adhesive layer, if necessary. The intermediate layer may be, for example, an elastic layer, a rigid layer, or the like, or may be the resin layer of the laminate film (1). However, since the laminate film (3) of the present invention is used as an adhesive tape or an adhesive sheet, it is preferable that the above-mentioned release layer or a release layer equivalent thereto does not exist between the base film and the pressure-sensitive adhesive layer. For example, when the pressure-sensitive adhesive layer side of the laminate film (3) of the present invention is attached to a commercially available soda-lime glass plate and peeled off after 5 minutes, it is preferable that the pressure-sensitive adhesive layer is peeled off together with the base film.

[0130] The laminated film (3) of the present invention can be used in various applications as an adhesive tape or adhesive sheet. For example, for optical applications, it can be used as: protective films for image display devices, image display panels, touch panels, polarizing plates, etc.; shatterproof films incorporated into image display devices, etc.; protective films for lenses, prism sheets, etc.; for architectural and structural members, it can be used as: decorative sheets for laminated glass, windows, mirrors, etc., infrared and ultraviolet blocking films for windows, etc.; decorative films for steel plates, films for signs, advertisements, and signs; and for office applications, it can be used as: office tape, sticky note tape, labels, price tags, and packing tape.

[0131] Next, the effects of the present invention will be described using examples and comparative examples. First, the evaluation methods of the characteristic values ​​used in the present invention will be described below.

[0132] [Evaluation Methods] The following (A) relates to the measurement of the physical properties of a longitudinally uniaxially stretched film used in the manufacturing process of a biaxially oriented polylactic acid film, and the following (B) relates to the evaluation of the manufacturing process of a biaxially oriented polylactic acid film. The physical properties of the obtained biaxially oriented polylactic acid film were measured by the following methods (1) to (10).

[0133] (A) Using a NETZSCH DSC214 crystallization degree, glass transition temperature, and melting point measuring device, 10 mg of a longitudinally uniaxially stretched film sample was measured for heat flux when the sample was heated from room temperature to 200°C at a rate of 10°C / min. From the obtained heat flux, the heat quantity ΔHca' (low-order α' crystals) at the exothermic peak at (Tc) < 100°C, the heat quantity ΔHca (high-order α crystals) at the exothermic peak at 120°C ≦ (Tc), and the heat of fusion ΔHm at the endothermic peak at the melting point were calculated. Next, using the equilibrium heat of fusion of perfectly crystalline polylactic acid (93.6 J / g), the crystallinity was calculated using the following formula: The glass transition temperature (Tg) of FY801 resin was determined from the midpoint of the displacement. The melting point (Tm) was determined from the maximum point of the endothermic peak. Crystallinity (%) = (ΔHm-ΔHca'-ΔHca) / 93.6

[0134] (B) Uniformity in Width Direction of Transverse Stretching (TD) The film passability in the transverse (TD) stretching step was evaluated according to the following criteria. ∘: Film passability was stable, and uniform stretching in the film width direction was possible. ×: Film passability was stable, but non-uniform stretching in the film width direction occurred.

[0135] (1) Mesophase Orientation Parameters For the surface of the biaxially oriented polylactic acid film, an infrared absorption spectrum was obtained by using the attenuated total reflection (ATR) method of Fourier transform infrared spectroscopy (FT-IR) with the film longitudinal direction parallel to the direction of incidence of infrared light (Fig. 1). －１ Absorbance A (crystal / mesophase) and 2996 cm －１ The mesophase orientation parameter was calculated from the ratio of the absorbance B (internal standard band) at 1000 nm to the absorbance B at 1000 nm (internal standard band). The specific measurement conditions for the infrared absorption spectrum are as follows. (Measurement) Spectroscopic device: Fourier transform infrared spectrophotometer (Agilent Technologies Cary670) Accessory: Single reflection ATR attachment (SPECAC golden gate MKII) Polarizer: Wire grid, P-polarized light ATR crystal: Diamond Incident angle: 45° Number of accumulations: 64 Resolution: 4 cm －１ Wave number range: 650 cm －１ ~4000cm －１・Absorbance A: 710cm －１ ~730cm －１ The minimum value between －１ Approximately 760 cm when the line connecting the －１ Peak height / absorbance B: 2800 cm －１ From 3200 cm －１ Approximately 3000 cm when the line connecting the －１ Peak height at Calculation formula: Mesophase orientation parameter = absorbance A (757 cm －１ ) / absorbance B(2996cm －１ If the longitudinal and transverse directions of the film are unknown, the orientation angle can be measured using a microwave molecular orientation system (for example, MOA-8000 manufactured by Oji Scientific Instruments Co., Ltd.) and the like, and the orientation can be appropriately determined.

[0136] (2) Thickness The thickness of the biaxially oriented polylactic acid film was measured using a TH-104 manufactured by Tester Sangyo Co., Ltd. The thickness was determined as the average value of measurements taken at three points at 50 mm intervals in the machine direction at the center of the film.

[0137] (3) Haze In accordance with JIS-K-7136, the diffuse transmittance (%) and total light transmittance (%) of the biaxially oriented polylactic acid film were measured using a turbidity meter NDH-7000-2 manufactured by Nippon Denshoku Industries Co., Ltd., and the haze (%) was calculated using the following formula: Haze (%) = ((diffuse transmittance / total light transmittance)) x 100

[0138] (4) Internal Haze The haze of the biaxially oriented polylactic acid film was measured using a turbidity meter NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd., and then silicone oil (KF-54) manufactured by Shin-Etsu Silicone Co., Ltd. was applied to the back side of the sample measurement surface (the side opposite to the incident light from the light source) to measure the internal haze of the biaxially oriented polylactic acid film.

[0139] (5) Total Light Transmittance The total light transmittance (%) of the biaxially oriented polylactic acid film was measured in accordance with JIS K 7136 using a turbidimeter NDH-7000 Type 2 manufactured by Nippon Denshoku Industries Co., Ltd.

[0140] (6) Breaking Stress The breaking stress of biaxially oriented polylactic acid films was measured in accordance with JIS-C-2318. A sample was prepared by cutting a strip of 120 mm long and 10 mm wide across the width of the film using a single-edged razor. Next, using an Autograph AG-IS manufactured by Shimadzu Corporation, the strip sample was clamped with a chuck distance of 100 mm and pulled at a rate of 100 mm / min. The breaking strength (MPa) in the longitudinal direction (machine direction: MD) and the transverse direction (TD) was calculated from the obtained stress at break. The ratio of the breaking stress in the longitudinal direction to the transverse direction (MD / TD) was calculated from the obtained results.

[0141] (7) Tensile Modulus The breaking stress of biaxially oriented polylactic acid films was measured in accordance with JIS-C-7127. A sample was prepared by cutting a strip of 120 mm long and 10 mm wide across the width of the film using a single-edged razor. Next, using an Autograph AG-IS manufactured by Shimadzu Corporation, the strip sample was clamped with a chuck distance of 100 mm and pulled at a rate of 100 mm / min to obtain a nominal stress-nominal strain curve. The tensile modulus (GPa) in the machine direction (longitudinal direction: MD) and the transverse direction (TD) was then calculated from the stress gradient (the following formula) in the 1-2% strain range. Tensile modulus (GPa) = stress / strain

[0142] (8) Heat Shrinkage The heat shrinkage of biaxially oriented polylactic acid films was measured in accordance with JIS-C-2318. A sample was cut into a width of 10 mm and a length of 190 mm in the longitudinal direction (machine direction: MD) of the film, and marks were made at 150 mm intervals along the length. The distance between the marks (A) was measured. The film was then placed in an oven in an atmosphere of 150°C and heat-treated at 150±3°C for 30 minutes under no load, after which the distance between the marks (B) was measured. The heat shrinkage in the machine direction (machine direction: MD) and the width direction (TD) at 150°C was calculated using the following formula. The heat shrinkage in the width direction (TD) was calculated based on the width of the sample. 150°C heat shrinkage (%) = {(A-B) / A} x 100

[0143] (9) Dynamic Friction Coefficient The dynamic friction coefficient of the biaxially oriented polylactic acid film was measured in accordance with JIS-K-7125. A sample was prepared with a surface 70 mm wide and 200 mm long in the machine direction of the film, and a back surface 50 mm wide and 50 mm long in the machine direction of the film. Next, using a Tensilon universal testing machine RGT-1210 manufactured by AND (A & D) as the measuring device, the back surface was slid against the front surface of the film at a load of 4.4 kg and a speed of 200 mm / min to determine the dynamic friction coefficient (μd).

[0144] (10) Judgment of processing characteristics The cutting ability of biaxially oriented polylactic acid film was judged by sensory evaluation when punching was performed using a rotary cutter die manufactured by Tsukatani Hamono Co., Ltd. The judgment criteria were as follows. The occurrence of cracks or breaks during punching is expected to lead to breakage or the generation of chips in the slitting process during production, and further to interfacial peeling in the case of a laminate. If breakage is induced, productivity will decrease, and if chips are induced, there is a risk of affecting the quality, such as defects in the film. Judgment: ◎: The cut surface was smooth and free of cracks or breaks. Judgment: ◯: Slight cracks or breaks were observed on the cut surface. Judgment: ×: Cracks or breaks were observed on the cut surface.

[0145] For Examples 1 to 6 and Comparative Examples 1 to 4, evaluation was carried out in the manufacturing process of the biaxially oriented polylactic acid film described above in (B). The results are shown in Table 1. Furthermore, evaluation of the physical properties of the obtained biaxially oriented polylactic acid films was carried out for the above (1) to (4) and (6) to (10). The results are shown in Table 2.

[0146] Example 1 (1) Preparation of Polylactic Acid Resin: Poly-L-lactic acid, brand FY801 (L-lactic acid / D-lactic acid mass ratio 99 / 1) manufactured by Anhui Fengyuan Group Co., Ltd. was used as the polylactic acid resin. The glass transition temperature (Tg) of FY801 resin was 60°C, and the melting point (Tm) was 180°C. SYLYSIA310P manufactured by Fuji Silysia Chemical Ltd. was used as the inorganic particles. 0.5% by mass of SYLYSIA310P (average particle size 2.7 μm) was added to FY801, and the mixture was pelletized to prepare a lubricant masterbatch raw material with a lubricant concentration of 0.45% by mass. Next, FY801 was dry-blended with 0.67% of the lubricant masterbatch raw material to prepare a raw material.

[0147] (2) Production of Biaxially Oriented Polylactic Acid Film: Poly-L-lactic acid (FY801) was dried under reduced pressure (1 Torr) at 80°C for 24 hours, and then the dry blend raw material described in (1) above was fed to an extruder. The mixture was melted at 220°C and extruded into a sheet from a die. The gear pump rotation speed was controlled to achieve a thickness of approximately 450 μm. The extruded molten resin was then cast onto a cooling drum with a surface temperature of 40°C, and was cooled and solidified by adhering it to the surface of the cooling drum using an electrostatic application method, producing an unstretched film with a thickness of 450 μm.

[0148] The obtained unstretched film was heated to 60°C using a group of heated rolls, and then the film was further heated with a focused IR output of 9.0 A and stretched 3.0 times in the longitudinal direction using a group of rolls with different peripheral speeds to produce a longitudinally uniaxially stretched film.

[0149] The resulting longitudinally uniaxially stretched film was then introduced into a tenter, held with clips, and preheated at 75°C before being transversely stretched. The transverse stretching temperature was 90°C, the transverse stretching ratio was 4.0, and heat treatment was performed at 140°C for 12 seconds. Subsequently, a relaxation treatment (140°C, 3%) was performed after transverse stretching to obtain a biaxially oriented polylactic acid film. In Example 1, the transverse stretching temperature was set to 90°C or higher, and the transverse stretching ratio was reduced to 4.0. Specifically, by controlling the stretching temperature and ratio, excessive orientation during the stretching process, i.e., mesophase orientation, was suppressed, and internal haze was reduced, resulting in a film with excellent transparency. The physical properties of the resulting film of Example 1 are shown in Table 2.

[0150] Example 2 In Example 2, a biaxially oriented polylactic acid film was obtained in the same manner as in Example 1, except that the stretching conditions were changed as shown in Table 1. The physical properties of the obtained film of Example 2 are shown in Table 2. In Example 2, the transverse stretching ratio was increased, while the longitudinal stretching temperature and the transverse stretching temperature were also increased. This further suppressed excessive orientation during the stretching process, i.e., mesophase orientation, and resulted in a film with superior transparency. As can be seen from the cross-sectional photograph of the film shown in Figure 2, the occurrence of crazes was significantly improved compared to the film of Comparative Example 1 shown in Figure 3. Furthermore, as an effect of increasing the transverse stretching ratio, the effect of reducing the thermal shrinkage rate in the longitudinal direction due to relaxation of the molecular chains in the longitudinal direction was obtained.

[0151] (Example 3) In Example 3, a biaxially oriented polylactic acid film was obtained in the same manner as in Example 1, except that the stretching conditions were changed as shown in Table 1. The physical properties of the obtained film of Example 3 are shown in Table 2. In Example 3, by reducing the stretching ratio in the longitudinal direction, mesophase orientation was further suppressed, and a film with superior transparency was obtained by suppressing orientation at the time of longitudinal stretching even while containing inorganic particles. Controlling not only the transverse stretching temperature and ratio but also the orientation in the longitudinal direction is suitable for controlling mesophase orientation, and can be a means of achieving the present invention.

[0152] Example 4 In Example 4, a biaxially oriented polylactic acid film containing no inorganic particles was obtained in the same manner as in Example 1, except that (1) the lubricant masterbatch raw material was not used in the preparation of the polylactic acid-based resin and the stretching conditions were changed as shown in Table 1. The physical properties of the obtained film of Example 4 are shown in Table 2. In Example 4, by increasing the transverse stretching temperature and heat setting temperature, mesophase orientation was suppressed, and a film with excellent transparency was obtained. Furthermore, by increasing the heat setting temperature, the mobility of molecular chains was suppressed by the crystallization treatment at high temperature, and a film with excellent thermal shrinkage in the longitudinal and transverse directions was obtained.

[0153] Example 5 In Example 5, a biaxially oriented polylactic acid film containing no inorganic particles was obtained in the same manner as in Example 4, except that the stretching conditions were changed as shown in Table 1. The physical properties of the obtained film of Example 5 are shown in Table 2. In Example 5, the transverse stretching temperature and stretching ratio were higher than in Example 4, and by controlling the mesophase orientation through the balance between the stretching temperature and ratio, a film with excellent transparency could be obtained. Furthermore, by increasing the heat setting temperature, the mobility of molecular chains was suppressed by the crystallization treatment at high temperature, and a film with excellent heat shrinkage in both the longitudinal and transverse directions could be obtained.

[0154] (Example 6) In Example 6, a biaxially oriented polylactic acid film containing no inorganic particles was obtained in the same manner as in Examples 4 and 5, except that the stretching conditions were changed to those shown in Table 1. The physical properties of the obtained film of Example 6 are shown in Table 2. In Example 6, the stretching temperature was lowered, but the stretch ratio was also relatively low, and sufficient transparency was obtained.

[0155] As specifically shown in Examples 1 to 6 above, by controlling the meso-orientation by the stretching temperature and ratio, it is possible to obtain biaxially oriented polylactic acid films that are compatible with transparency and processability without compromising strength and heat resistance, have good dimensional stability even at high temperatures, and have high transparency suitable for industrial applications. Furthermore, the surface roughness of the biaxially oriented polylactic acid films obtained in Examples 1 to 6 was a maximum protrusion height (P) of 200 nm or less and an arithmetic mean roughness (Sa) of 10 nm or less, making them suitable for use as base films for release films used in the production of ceramic green sheets.

[0156] Comparative Examples 1 and 2: In Comparative Examples 1 and 2, biaxially oriented polylactic acid films containing inorganic particles were obtained in the same manner as in Example 1, except for the stretching conditions shown in Table 1. The physical properties of the obtained films of Comparative Examples 1 and 2 are shown in Table 2. In Comparative Examples 1 and 2, the low transverse stretching temperature resulted in the mesophase around the crystals formed during longitudinal stretching being stretched without being completely disentangled. Furthermore, the high transverse stretching ratio likely led to accelerated crystallization during transverse stretching, which in turn led to the orientation of the mesophase, resulting in excessive mesophase orientation. Comparative Example 2 had an even higher stretching ratio, which disrupted the stretching uniformity. Furthermore, the inclusion of inorganic particles significantly increased crazes within the film, significantly impairing transparency. Furthermore, the processability was also impaired, making this film outside the scope of the present invention. Figure 3 shows a cross-sectional photograph of the film of Comparative Example 1. It can be seen that numerous crazes were present.

[0157] Comparative Example 3 In Comparative Example 3, a biaxially oriented polylactic acid film containing no inorganic particles was obtained in the same manner as Comparative Example 1, except that the lubricant masterbatch raw material was not used and the stretching conditions were changed to those shown in Table 1. The physical properties of the obtained film of Comparative Example 3 are shown in Table 2. In Comparative Example 3, inorganic particles were not included and the stretching ratio was increased compared to Example 1, resulting in a deterioration in internal haze. This is because, even though the stretching temperature was 90°C, the increased stretching ratio increased oriented crystallization during transverse stretching, increasing meso-orientation, resulting in the occurrence of crazes, i.e., the internal haze and haze were deteriorated, and therefore this film is outside the scope of the present invention. Since the film of Comparative Example 3 does not contain particles, crazes are unlikely to occur, but as can be seen from the cross-sectional photograph shown in Figure 4, crazes were observed.

[0158] (Comparative Example 4) In Comparative Example 4, a biaxially oriented polylactic acid film containing no inorganic particles was obtained in the same manner as in Comparative Example 1, except that the stretching conditions were changed to those shown in Table 1. The physical properties of the obtained film of Comparative Example 4 are shown in Table 2. In Comparative Example 4, the transverse stretching temperature was equivalent to that of the Examples, and the film was excellent in transparency, but the temperature and magnification of the longitudinal uniaxial stretching were low, resulting in a decrease in crystallinity at the time of longitudinal uniaxial stretching and uneven thickness, and a uniform temperature rise and force were not applied during transverse stretching, resulting in non-uniform film passability in the width direction. Therefore, the film is not suitable from the standpoint of quality and is outside the scope of the present invention.

[0159] As described above, when inorganic particles are contained in the films obtained in Comparative Examples 1 to 4, crazes are significantly generated inside the film, impairing transparency. Typical examples of crazes are shown in Figure 2, which shows SEM cross-sectional images of Example 2 and Comparative Example 1. Furthermore, even when polylactic acid is used alone, depending on the crystallinity at the time of longitudinal uniaxial stretching and the transverse stretching conditions, it may not be suitable for film permeability, transparency, or processing characteristics in transverse stretching. These issues can be resolved by controlling the mesophase orientation.

[0160]

[0161]

[0162] [Evaluation Method] For Examples 11 to 19 and Comparative Examples 11 to 14, evaluations were carried out in the same biaxially oriented polylactic acid film manufacturing process as in (B) above. The results are shown in Table 3. Furthermore, the physical properties of the laminated film (1) having a resin layer were measured by the methods (1) to (8) and (10) above. The dynamic friction coefficient (9) above was measured by the method (9') below. Furthermore, the physical properties (11) below were measured and the evaluation (12) below was performed. The results are shown in Table 4.

[0163] Regarding the measurement of the physical property (1) above, the penetration depth of the measurement light in the attenuated total reflection (ATR) method of Fourier transform infrared spectroscopy (FT-IR) is 2 to 3 μm, and for laminated films (1) having a resin layer, measurements can be performed on biaxially oriented polylactic acid films (substrate films) as long as the resin layer is 0.5 μm thick or less. Furthermore, the physical properties (2) to (4), (6) to (8), and (10) above are not affected by the resin layer as long as the resin layer is 0.5 μm thick or less (even if they are affected, it is only to the extent of measurement error). If the resin layer is too thick to detect the absorbance peak, the resin layer can be scraped off with a razor or the like before measuring the physical properties (1) to (8), and (10) above.

[0164] (9') Dynamic Friction Coefficient The dynamic friction coefficient of the laminate film (1) having a resin layer was measured in accordance with JIS-K-7125. A 70 mm wide, 200 mm long sample (Sample A) was cut out of the film with the longitudinal direction as the length direction, and the surface opposite the resin layer of Sample A was fixed to a table. Separately, a 50 mm wide, 50 mm long sample (Sample B) was cut out of the same film, and the surface opposite the resin layer of Sample B was attached to a slide (50 mm wide, 50 mm long). Next, the film surface of Slide B was placed parallel to Sample A on the table in the longitudinal direction of the film. Using an AND (A&D) Tensilon Universal Testing Machine RGT-1210 as the measuring device, a 4.4 kg load was applied to the slide, and the slide was slid along the length of Sample A at a speed of 200 mm / min to determine the dynamic friction coefficient (μd) between the resin layer surface of the film and the surface opposite the resin layer.

[0165] (11) Surface Free Energy γs of Resin Layer After leaving the laminate film (1) having a resin layer in an atmosphere of 50% relative humidity for 24 hours, the contact angles of distilled water and diiodomethane were measured 1 minute after dropping them onto the resin layer using a FACE contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., CA-X model). Five measurements were taken for each sample, and the average of the three measurements excluding the maximum and minimum values ​​was used as the contact angle. The diffusion component γs of the surface free energy was calculated from the contact angles of distilled water and diiodomethane.

[0166] (12) Coating appearance of resin layer The surface of laminated film (1) having a resin layer, on which the resin layer was laminated, was irradiated with light from a bromine light source (VIDEOLIGHT VLG301 100V 300W, manufactured by LPL) and a fluorescent lamp (Panasonic Paluk, F.L 15EX-N 15W, three-wavelength daylight white) at an angle of approximately 10° to 45° relative to the film surface, and the coating appearance of the resin layer was judged by visual observation according to the following criteria: A: No coating unevenness, coating streaks, or repelling was observed under either bromine light or fluorescent light, resulting in a uniform coated surface. B: Coating unevenness, coating streaks, repelling, etc. were observed under bromine light but not under fluorescent light. C: Coating unevenness, coating streaks, repelling, etc. were observed under both bromine light and fluorescent light. Coating appearances ranked A or B were judged to be good, and coating appearances ranked A were judged to be particularly good.

[0167] The methods for preparing the aqueous resins used in the resin layers and the coating solutions for forming the resin layers used in Examples 11 to 19 and Comparative Examples 11 to 14 are as follows.

[0168] (1) Preparation of aqueous resin used in resin layer Dimethyl terephthalate (95 parts by mass), dimethyl isophthalate (95 parts by mass), ethylene glycol (35 parts by mass), neopentyl glycol (145 parts by mass), zinc acetate (0.1 parts by mass), and antimony trioxide (0.1 parts by mass) were charged into a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser, and a transesterification reaction was carried out at 180 ° C. for 3 hours. Next, 5-sodium sulfoisophthalic acid (6.0 parts by mass) was added, and an esterification reaction was carried out at 240 ° C. for 1 hour. After that, a polycondensation reaction was carried out at 250 ° C. under reduced pressure (10 to 0.2 mmHg) for 2 hours to obtain a copolymer polyester resin (A) having a number average molecular weight of 19,500 and a softening point of 60 ° C. 30 parts by mass of the polyester resin (A) and 15 parts by mass of ethylene glycol n-butyl ether were placed in a reactor equipped with a stirrer, a thermometer, and a reflux device, and the mixture was heated to 110°C and stirred to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was gradually added to the polyester solution while stirring. After the addition, the liquid was cooled to room temperature while stirring to prepare a milky white polyester resin aqueous dispersion with a solids content of 30% by mass.

[0169] (2) Preparation of coating liquid (resin layer forming material) for forming resin layer The following coating agents were mixed to prepare coating liquids A, B, C, and D. (Coating liquid A) Water 46.89% by mass Isopropanol 30.00% by mass Polyester resin water dispersion 20.00% by mass MP4540M 0.08% by mass (manufactured by Nissan Chemical Industries, solid content 40% by mass, average particle size 450 nm) Snowtex ST-XL 3.00% by mass (manufactured by Nissan Chemical Industries, solid content 30% by mass, average particle size 45 nm) Surfactant 0.03% by mass (silicone-based, solid content 100% by mass)

[0170] (Coating Solution B) Water 52.25% by mass Isopropanol 30.00% by mass Nikazol RX-2035A 13.64% by mass (acrylic resin water dispersion, manufactured by Nippon Carbide Corporation, solid content 44% by mass) MP4540M 0.08% by mass (manufactured by Nissan Chemical Industries, solid content 40% by mass, average particle size 450 nm) Snowtex ST-XL 3.00% by mass (manufactured by Nissan Chemical Industries, solid content 30% by mass, average particle size 45 nm) Surfactant 0.03% by mass (silicone-based, solid content 100% by mass)

[0171] (Coating Solution C) Water 40.80% by mass Isopropanol 30.00% by mass Hydran AP-201 26.09% by mass (Polyurethane resin water dispersion, manufactured by DIC Corporation, solid content 23% by mass) MP4540M 0.08% by mass (Manufactured by Nissan Chemical Industries, solid content 40% by mass, average particle size 450 nm) Snowtex ST-XL 3.00% by mass (Manufactured by Nissan Chemical Industries, solid content 30% by mass, average particle size 45 nm) Surfactant 0.03% by mass (Silicone-based, solid content 100% by mass)

[0172] (Coating liquid D) Water 42.89% by mass Isopropanol 30.00% by mass Zaixen L 24.00% by mass (polyolefin resin water dispersion, manufactured by Sumitomo Seika Chemicals Co., Ltd., solid content 25% by mass) MP4540M 0.08% by mass (manufactured by Nissan Chemical Industries, Ltd., solid content 40% by mass, average particle size 450 nm) Snowtex ST-XL 3.00% by mass (manufactured by Nissan Chemical Industries, Ltd., solid content 30% by mass, average particle size 45 nm) Surfactant 0.03% by mass (silicone-based, solid content 100% by mass)

[0173] Example 11 In Example 11, the same procedure as in Example 1 was carried out, except that after preparing a longitudinally uniaxially stretched film, the coating solution A used to form the resin layer was applied to one side of the resulting uniaxially stretched film by a fountain bar coating method, adjusting the coating amount so that the resin layer thickness was 50 nm on the laminated polylactic acid film. Subsequently, this in-line coated longitudinally uniaxially stretched film was introduced into a tenter and held with clips. The resulting longitudinally uniaxially stretched film was introduced into the tenter and held with clips, preheated at 75°C, and then transversely stretched. The transverse stretching temperature was 90°C, the transverse stretching ratio was 4.0 times, and heat treatment was carried out at 140°C for 12 seconds. Next, relaxation treatment (140°C, 3%) was carried out after transverse stretching to obtain a laminated film (1) having a resin layer. The physical properties of the resulting film of Example 11 are shown in Table 4. In Example 11, similarly to Example 1, the occurrence of crazes was suppressed and internal haze was reduced by controlling the meso-orientation, thereby obtaining a laminated film (1) having a resin layer with excellent transparency. In addition, the coating appearance of the resin layer was particularly good.

[0174] (Examples 12 to 16 and Comparative Examples 11 to 14) In Examples 12 to 16 and Comparative Examples 11 to 14, laminate films (1) having a resin layer were obtained in the same manner as in Example 11, except that the presence or absence of a lubricant masterbatch material (inorganic particles) and the stretching conditions were changed as shown in Table 3. The physical properties of the obtained films of Examples 12 to 16 and Comparative Examples 11 to 14 are shown in Table 4. Note that the presence or absence of a lubricant masterbatch material (inorganic particles) and the stretching conditions of Examples 12 to 16 were the same as in Examples 1 to 6 and Comparative Examples 1 to 4. In Examples 12 to 16, similar to Examples 1 to 6, the meso-orientation was controlled to suppress the occurrence of crazes and reduce internal haze, thereby enabling the production of laminate films (1) having a resin layer with excellent transparency. Furthermore, the coating appearance of the resin layer was particularly good. On the other hand, in Comparative Examples 11 to 13, the occurrence of crazes was observed, as in Comparative Examples 1 to 3, and in Comparative Example 14, as in Comparative Example 4, the temperature and magnification of the longitudinal uniaxial stretching were low, which reduced the crystallinity at the time of longitudinal uniaxial stretching and resulted in non-uniform film passability in the width direction during transverse stretching, and therefore this is not preferable from the viewpoint of quality.

[0175] (Example 17) In Example 17, a laminated film (1) having a resin layer not containing inorganic particles was obtained in the same manner as in Examples 14 to 16, except that Coating Solution B used to form the resin layer was used and the stretching conditions were changed as shown in Table 3. The physical properties of the obtained film of Example 17 are shown in Table 4. In Example 17, the stretching temperature was lowered, but the stretching ratio was also relatively low, and sufficient transparency was obtained.

[0176] (Example 18) In Example 18, a laminated film (1) having a resin layer not containing inorganic particles was obtained in the same manner as in Examples 14 to 17, except that the coating solution C used to form the resin layer was used and the stretching conditions were changed as shown in Table 3. The physical properties of the obtained film of Example 18 are shown in Table 4. In Example 18, the stretching temperature was lowered, but the stretching ratio was also relatively low, and sufficient transparency was obtained.

[0177] As specifically shown in Examples 11 to 18 above, by controlling the meso-orientation by the stretching temperature and ratio, it is possible to obtain a biaxially oriented polylactic acid film that is compatible with transparency and processability without compromising strength and heat resistance, has good dimensional stability even at high temperatures, and has high transparency suitable for industrial applications. Furthermore, the surface roughness of the resin-layer-free side of the laminated film (1) having a resin layer obtained in Examples 11 to 18 was a maximum protrusion height (P) of 200 nm or less and an arithmetic mean roughness (Sa) of 10 nm or less, making it suitable as a release film for producing ceramic green sheets.

[0178] Example 19 In Example 19, a laminated film (1) having a resin layer not containing inorganic particles was obtained in the same manner as in Example 14, except that the coating liquid D used to form the resin layer was used and the conditions were changed as shown in Table 3. The physical properties of the obtained film of Example 19 are shown in Table 4. In Example 19, it was shown that by increasing the transverse stretching temperature and heat setting temperature as in Example 14, mesophase orientation was suppressed and a film with excellent transparency was obtained, but the surface free energy was low and the coating appearance of the resin layer was poor.

[0179]

[0180]

[0181] [Evaluation Method] For Examples 21 to 30, evaluations were carried out in the same biaxially oriented polylactic acid film production process as in (B) above. The results are shown in Table 6. In addition, the physical properties of the laminated film (1) having a resin layer (containing an antistatic agent) were measured by the methods (1) to (8), (9'), and (10) above.

[0182] The resin layer-forming coating solutions E to I (resin layer-forming materials) used in Examples 21 to 30 were prepared by adding the following antistatic agents to the polyester resin water dispersion, silica particles, water, isopropanol, and silicone surfactant (solid content concentration 100% by mass) used in preparing the above-mentioned coating solution A, and mixing them in the proportions shown in Table 5. Table 5 also shows the amount (% by mass) of the antistatic agent contained in the resin layer.

[0183] (Ion conductive type antistatic agent) TB702 (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., solid content 50% by mass) (Conductive polymer type antistatic agent) Orgacon ICP1010 (manufactured by Agfa Materials Japan, solid content 1.2% by mass)

[0184]

[0185] (13) Antistatic property: Surface resistivity of resin layer Five 5.0 cm square pieces were cut out of the laminated film (1') to prepare samples. The resin layer surfaces of the samples were measured for each of the five pieces in accordance with JIS K6911 using a surface resistivity measuring instrument (Hiresta MCP-HT800, manufactured by Nitto Seiko Analic) at 23°C and 65% humidity with an applied voltage of 500 V, and the average value was taken as the surface resistivity. When the surface resistivity was 1.0 x 10 １4 Those with a resistance of 1.0×10 Ω / sq or less are considered to have antistatic properties, and １3 Those having a value of Ω / sq or less were judged to have good antistatic properties.

[0186] <Preparation of a laminated film (1') having a resin layer containing an antistatic agent laminated thereon> (Example 21) In Example 21, after preparing a longitudinally uniaxially stretched film in Example 1, the coating solution E used for forming a resin layer was applied to one side of the obtained uniaxially stretched film by a fountain coat method to a laminated polylactic acid film in an amount of 5.0 g / m ２ The same operation as in Example 1 was performed, except that the in-line coated longitudinal uniaxially stretched film was adjusted to about 100% and coated. Subsequently, the in-line coated longitudinal uniaxially stretched film was introduced into a tenter and held with clips. The resulting longitudinal uniaxially stretched film was introduced into the tenter and held with clips. It was preheated at 75°C and then transversely stretched. The transverse stretching temperature was 90°C, the transverse stretching ratio was 4.0 times, and the film was heat-treated at 140°C for 12 seconds. Next, after transverse stretching, a relaxation treatment (140°C, 3%) was performed to obtain a laminated film (1') having a resin layer containing an antistatic agent. The physical properties of the obtained film of Example 21 are shown in Table 7. In Example 21, as in Example 1, by controlling the meso-orientation, the occurrence of crazes was suppressed and internal haze was reduced, thereby obtaining a laminated film (1') having a resin layer containing an antistatic agent with excellent transparency. Furthermore, the film also had sufficient antistatic properties.

[0187] Examples 22 to 26 In Examples 22 to 26, laminate films (1') having a resin layer containing an antistatic agent were obtained in the same manner as in Example 21, except that the presence or absence of a lubricant masterbatch material (inorganic particles) and the stretching conditions were changed as shown in Table 6. The physical properties of the obtained films of Examples 22 to 26 are shown in Table 4. Note that the presence or absence of a lubricant masterbatch material (inorganic particles) and the stretching conditions of Examples 22 to 26 were the same as in Examples 1 to 6 and Comparative Examples 1 to 4. In Examples 22 to 26, similar to Examples 1 to 6, meso-orientation was controlled to suppress the occurrence of crazes and reduce internal haze, thereby enabling the production of laminate films (1') having a resin layer containing an antistatic agent with excellent transparency. Furthermore, the films also had sufficient antistatic properties.

[0188] (Examples 27 to 30) The same procedure as in Example 21 was carried out, except that Coating Solution E used to form the resin layer was changed to the coating solution shown in Table 6, to obtain laminate films (1') each having a resin layer containing an antistatic agent laminated thereon. The films also had sufficient antistatic properties.

[0189]

[0190]

[0191] In addition, the resin layer-laminated films (1) obtained in Examples 11 to 19 did not contain an antistatic agent in the resin layer, and therefore the surface resistivity of the resin layer was 1.0 × 10 １５ It was over Ω / sq.

[0192] <Formation of Release Layer> The following coating liquid was applied as a release layer-forming material to one surface of the biaxially oriented polylactic acid film (substrate film) obtained in Examples 1 to 6 in an amount of 5.0 g / m ２ The coating was applied by gravure coating to a thickness of about 100°C, dried for 30 seconds at a temperature of 100°C, and then irradiated with ultraviolet light (100 mJ / cm) using an electrodeless lamp (H bulb manufactured by Fusion Co., Ltd.). ２ ) was carried out to obtain a laminated film (2) having a release layer.

[0193] In addition, a release layer was formed on the surface opposite to the resin layer of the laminate film (1) having a resin layer obtained in Examples 11 to 18 and the laminate film (1') having a resin layer obtained in Examples 21 to 30 in the same manner as above, thereby obtaining a laminate (resin layer / substrate film / release layer) that combined the aspects of the laminate film (2).

[0194] <<Release Layer Forming Material>> Cation-curable siloxane resin KR-470 (Shin-Etsu Chemical Co., Ltd., solids content 100%, alicyclic epoxy group-containing siloxane tetrafunctional oligomer): 7.53 parts by weight, acid generator Silicolyse UV CATA211 (Arakawa Chemical Industries, Ltd., solids content 18%): 1.12 parts by weight, methyl ethyl ketone: 54.33 parts by weight, toluene: 18.30 parts by weight, normal heptane: 18.3 parts by weight

[0195] [Evaluation Method] (14) Surface Roughness Using a non-contact surface shape measurement system (VertScan R550H-M100), the arithmetic mean roughness (Sa) and maximum protrusion height (P) were measured as the average roughness of the area surface under the following conditions. The arithmetic mean roughness (Sa) was the average value of five measurements, and the maximum protrusion height (P) was the maximum value of the five measurements, excluding the maximum and minimum values, of seven measurements. (Measurement Conditions) Measurement mode: WAVE mode Objective lens: 10x, 0.5x Tube lens Measurement area: 936 μm x 702 μm (Analysis Conditions) Surface correction: 4th order correction Interpolation process: Full interpolation

[0196] The surface roughness of the release layer surface of the obtained laminate film (2) having a release layer, and the laminate (resin layer / substrate film / release layer) combining the form of the laminate film (1) or (1') was such that the maximum protrusion height (P) was 200 nm or less and the arithmetic mean roughness (Sa) was 10 nm or less, and the film was suitable for use as a release film for producing ceramic green sheets.

[0197] <Formation of Adhesive Layer> One side of the biaxially oriented polylactic acid film (substrate film) obtained in Example 1 was subjected to a corona treatment, and the following adhesive coating solution A was applied to this corona-treated surface and dried at 100°C to provide a 10 μm-thick acrylic adhesive layer, thereby obtaining a laminate film (3) having an adhesive layer. Similarly, laminate films (3) having an adhesive layer were obtained using the biaxially oriented polylactic acid films obtained in Examples 2 to 6. The laminate films (3) were useful as various surface protection films. In particular, the laminate films (3) having an adhesive layer using the substrate films of Examples 2 to 6, especially Examples 3 to 6, had low haze and were suitable for optical applications such as image display devices, image display panels, touch panels, and polarizing plates.

[0198] <Adhesive Coating Solution A> SK Dyne 1473H (manufactured by Soken Chemical & Engineering Co., Ltd.) 100 parts by mass Curing agent L-45 (manufactured by Soken Chemical & Engineering Co., Ltd.) 1.0 part by mass

[0199] <Formation of biomass-derived adhesive layer> One side of the biaxially oriented polylactic acid film (substrate film) obtained in Example 1 was subjected to a corona treatment, and the following adhesive coating solution B was applied to this corona-treated surface and dried at 90°C to provide a 20 µm thick acrylic adhesive layer made from a biomass-derived raw material, thereby obtaining a laminated film (3') having a biomass-derived adhesive layer. In the same manner, laminated films (3') having a biomass-derived adhesive layer were obtained using the biaxially oriented polylactic acid films obtained in Examples 2 to 6.

[0200] <Adhesive Coating Solution B> Biomass adhesive Oribain BPS6554 (manufactured by Toyochem Co., Ltd.) 100 parts, biomass content 15%

[0201] The laminated films (3) and (3') obtained above use the biaxially oriented polylactic acid film as the base film, and therefore when used as an adhesive tape or the like, problems such as cracks and breakage that occur during the production or processing of the adhesive tape or the like can be suppressed.

[0202] (15) Assessment of Environmental Load Since both the base film and the pressure-sensitive adhesive layer of the laminate film (3') are made from raw materials derived from biomass, the biomass content of the entire laminate film can be further increased, which greatly contributes to reducing the environmental load.

[0203] <Formation of Release Layer> A release layer was formed in the same manner as above on the surface opposite to the surface on which the pressure-sensitive adhesive layer was provided of the laminate film (3) or (3') having the pressure-sensitive adhesive layer obtained above, to obtain a laminate (pressure-sensitive adhesive layer / substrate film / release layer) that combines the embodiment of the laminate film (2) having a release layer. When the pressure-sensitive adhesive layer surface and the release layer surface of the obtained laminate (pressure-sensitive adhesive layer / substrate film / release layer) were bonded together and then peeled off, they were easily peeled off, and there was no problem even when the laminate was wound into a roll.

[0204] The polylactic acid film of the present invention and the laminate film (1) having a resin layer can be used in various applications. The laminate film (2) having a release layer of the present invention is suitable as a release film, for example, a release film for producing ceramic green sheets. The laminate film (3) having a pressure-sensitive adhesive layer of the present invention is suitable for use as various pressure-sensitive adhesive tapes or pressure-sensitive adhesive sheets.

Claims

1. A biaxially oriented polylactic acid film formed from a film-forming material containing polylactic acid, wherein the mesophase orientation parameter (757 cm) of the polylactic acid film is measured by the total reflection method of Fourier transform infrared spectroscopy. -１ / 2996cm -１ A biaxially oriented polylactic acid film having a peak intensity ratio of 4.0 or less.

2. The biaxially oriented polylactic acid film according to claim 1, having an internal haze of 6% or less.

3. A biaxially oriented polylactic acid film according to claim 1 or 2, which has a breaking stress in the width direction of 100 MPa or more and a ratio of breaking stress in the longitudinal direction to breaking stress in the width direction of 0.7 or less.

4. A biaxially oriented polylactic acid film according to any one of claims 1 to 3, which has a thermal shrinkage rate of 10% or less in the longitudinal direction when heated at 150°C for 30 minutes.

5. A biaxially oriented polylactic acid film according to any one of claims 1 to 4, wherein the polylactic acid has a mass ratio of L-lactic acid / D-lactic acid of 100 / 0 to 85 / 15.

6. The biaxially oriented polylactic acid film according to any one of claims 1 to 5, wherein the arithmetic mean roughness (Sa) of at least one surface of the biaxially oriented polylactic acid film is 10 nm or less and the maximum protrusion height (P) is 200 nm or less.

7. A laminated film having a base film and a release layer on at least one side of the base film, wherein the base film comprises the biaxially oriented polylactic acid film according to any one of claims 1 to 6.

8. The laminated film according to claim 7, wherein the release layer is formed from a release layer-forming material containing, as a release component, at least one member selected from the group consisting of silicone resin, fluororesin, alkyd resin, wax, and aliphatic olefin.

9. The laminated film according to claim 7 or 8, wherein the maximum protrusion height (P) of the surface of the release layer is 200 nm or less, and the arithmetic mean roughness (Sa) of the surface of the release layer is 10 nm or less.

10. The laminated film according to any one of claims 7 to 9, which is a release film for use in producing ceramic green sheets.

11. A laminated film having a base film and a resin layer on at least one side of the base film, wherein the resin layer is formed from a resin layer-forming material containing an aqueous resin, and the base film comprises the biaxially oriented polylactic acid film according to any one of claims 1 to 6.

12. The laminated film according to claim 11, wherein the surface free energy γs of the resin layer is 40 mN / m or more.

13. The biaxially oriented laminated polylactic acid film according to claim 11 or 12, wherein the resin layer is formed by an in-line coating method.

14. The laminated film according to any one of claims 11 to 13, wherein the resin layer-forming material contains an antistatic agent.

15. The surface resistivity of the surface of the resin layer is 1.0 × 10 １４ The biaxially oriented laminated polylactic acid film according to claim 14, having a modulus of elasticity of Ω or less.

16. A biaxially oriented laminated polylactic acid film according to claim 14 or 15, wherein the content of the antistatic agent is 5% by mass or more and 45% by mass or less relative to the aqueous resin of the resin layer forming material.

17. The laminated film according to any one of claims 14 to 16, which has a release layer on at least one surface thereof.

18. The laminated film according to claim 17, wherein the release layer is formed from a release layer-forming material containing, as a release component, at least one member selected from the group consisting of silicone resin, fluororesin, alkyd resin, wax, and aliphatic olefin.

19. The laminated film according to claim 17 or 18, wherein the maximum protrusion height (P) of the surface of the release layer is 200 nm or less, and the arithmetic mean roughness (Sa) of the surface of the release layer is 10 nm or less.

20. The laminated film according to any one of claims 17 to 19, which is a release film for producing ceramic green sheets.

21. A laminated film having a base film and an adhesive layer on at least one side of the base film, wherein the base film comprises the biaxially oriented polylactic acid film according to any one of claims 1 to 6.

22. The laminated film according to claim 21, wherein the adhesive layer contains raw materials derived from biomass.

23. The laminate film according to claim 22, wherein the pressure-sensitive adhesive layer is a layer containing an acrylic polymer, and at least one of the acrylic monomers that constitute the monomer components of the acrylic polymer is at least one selected from the group consisting of acrylic acid and methacrylic acid, which are biomass-derived raw materials.

24. The laminated film according to claim 11, which has an adhesive layer on one side of the base film and a release layer on the side opposite to the side having the adhesive layer.

25. The laminated film according to claim 24, wherein the release layer is formed from a release layer-forming material containing, as a release component, at least one member selected from the group consisting of silicone resin, fluororesin, alkyd resin, wax, and aliphatic olefin.

26. A laminated film according to claim 24 or 25, wherein the maximum protrusion height (P) of the surface of the release layer is 200 nm or less, and the arithmetic mean roughness (Sa) of the surface of the release layer is 10 nm or less.

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