Coating film and method for manufacturing the same

Abstract

The present invention provides a coating film with high uniformity of film thickness in the width direction of the coating layer, excellent appearance of the coating layer, and stable physical properties of various coating layers, as well as a method for manufacturing the same. [Solution] A roll-shaped coating film having a coating layer on at least one side of a base film, wherein the coating layer is stretched together with the base film at least in the width direction, the width of the coating layer is 1250 mm or more, and when points C1 and C2 are moved 200 mm from the center to both sides in the width direction, A1 is moved 25 mm toward the center from one end towards the center, A2 is moved 400 mm further, B1 is moved 25 mm toward the center from the other end towards the center, and B2 is moved 400 mm further, the average film thickness Tc of the coating layer between C1 and C2 and the average film thickness Tab between A1 and A2 and between B1 and B2 satisfy the relationship |Tab-Tc| / Tc×100≦10.

Description

Technical Field

[0001] The present invention relates to a coating film having a coating layer on at least one surface of a base film, and a method for producing the same. More specifically, the present invention relates to a coating film having a coating layer stretched at least in the width direction together with the base film, and a method for producing the same.

Background Art

[0002] Conventionally, a coating film in which a sheet-like film made of a thermoplastic resin, for example, a polyester film, a polyamide film, a polyolefin film, etc. is used as a base film and a functional layer is laminated thereon by coating has been widely used. Examples of the functional layer include an anti-scratch layer, an antifouling layer, an adhesive layer, an antistatic layer, an easy-adhesion layer, a release layer, a dielectric layer, a smoothing layer, and the like. Examples of the uses of the coating film having these functional layers include a hard coat film, a release film for the manufacturing process of various resin sheets, a surface protection film for optics, an easy-adhesion film, and the like.

[0003] As an example of a coating film, Patent Document 1 proposes a release film for a ceramic capacitor manufacturing process. Further, this document shows that the peelability and the smoothness of the coating layer surface deteriorate depending on the film thickness of the coating layer.

[0004] Patent Documents 2 and 3 propose a coating film produced by a method of coating a coating composition on one surface of a polyester film and then stretching the polyester film (hereinafter referred to as "in-line coating"). Patent Document 2 shows that the amount of film haze change and the transfer of oligomer components change depending on the film thickness of the coating layer. Further, Patent Document 3 shows that the adhesive properties, blocking properties, and transfer properties change depending on the film thickness of the coating layer.

[0005] Thus, when the thickness of the coating layer of a coating film is uneven, the function of the coating layer becomes difficult to perform properly, and therefore, there is a need to make the thickness of the coating layer uniform.

[0006] As an example of such technology, Patent Document 4 proposes a method for controlling the amount of coating by adjusting the contact pressure of the doctor blade that contacts the coating roller. Also, Patent Document 5 proposes a method for controlling the amount of coating by partially changing the diagonal engraving pattern of the coating plate. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6091287 [Patent Document 2] Japanese Patent Publication No. 2021-123049 [Patent Document 3] Japanese Patent Publication No. 2018-43241 [Patent Document 4] Japanese Patent Publication No. 2011-194350 [Patent Document 5] Japanese Patent Application Publication No. 11-156289 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, our own investigations have revealed that when a coating layer is formed by in-line coating, the thickness of the coating layer tends to become uneven due to stretching after coating. Specifically, since the coating layer is stretched simultaneously with the substrate film after the coating composition is applied, the thickness of the coating layer becomes smaller in areas that are stretched significantly, and larger in areas that are stretched less. As a result, the unevenness of the coating layer thickness due to the stretching of the substrate film tends to cause deterioration of the appearance of the coating layer and instability of various physical properties of the coating layer.

[0009] Therefore, the inventions described in Patent Documents 2 and 3 had a problem in that when a coating layer was formed by in-line coating, the thickness of the coating layer changed depending on the position in the width direction of the obtained film, resulting in unstable performance.

[0010] Furthermore, the invention described in Patent Document 4 did not address the above-mentioned problems when forming a coating layer by in-line coating, and there was a concern that the thickness of the coating layer would change depending on the position in the width direction of the obtained film in the case of in-line coating. In addition, Patent Document 4 assumes a large amount of coating, and when used for in-line coating, there was a concern that the temperature of the base film would not rise easily due to insufficient drying of the coating composition, making it more prone to breakage during stretching. Moreover, Patent Document 5 is a technique that increases the thickness of the coating layer at the edges to reduce the contact pressure in the center when wound into a roll, and therefore is incompatible with a technique to improve the uniformity of the film thickness.

[0011] Therefore, the present invention aims to provide a coating film that exhibits high uniformity of film thickness in the width direction of the coating layer, excellent appearance of the coating layer, and stable physical properties of various coating layers, as well as a method for manufacturing the same. [Means for solving the problem]

[0012] As a result of diligent research to solve the above problems, the inventors of the present invention have discovered that by adjusting the amount of coating applied during in-line coating according to the position in the width direction, a film with particularly high uniformity of film thickness in the width direction of the coating layer can be obtained, and have completed the present invention.

[0013] In other words, the present invention includes the following:

[0014] [1] A roll-shaped coating film having a coating layer on at least one side of a base film, The coating layer is stretched together with the base film at least in the width direction, The width of the aforementioned coating layer is 1250 mm or more. When a reference line L is drawn in the width direction, and points C1 and C2 are located on the reference line L and moved 200 mm to the left and right of the center of the width of the coating layer, and point A1 is located on the reference line L and moved 25 mm toward the center from one end of the coating layer, and point A2 is located 400 mm toward the center from A1, and point B1 is located on the reference line L and moved 25 mm toward the center from the other end of the coating layer, and point B2 is located 400 mm toward the center from B1, A coating film in which the average film thickness Tc of the coating layer on the central reference line L located between C1 and C2, and the average film thickness Tab of the coating layer on the reference lines L at both ends located between A1 and A2 and between B1 and B2, satisfy the relationship |Tab-Tc| / Tc×100≦10.

[0015] [2] The coating film described in [1], where the thickness of the coating layer measured at 150 mm intervals on a reference line L between A1 and B1 is Tmax, the maximum thickness is Tmin, and the average thickness is Tav, and the relationship (Tmax-Tmin) / Tav × 100 ≤ 30 is satisfied.

[0016] [3] The coating film according to [1] or [2], wherein the average film thickness Tav of the coating layer measured at 150 mm intervals on the reference line L between A1 and B1 is 0.005 μm or more and 1 μm or less.

[0017] [4] A coating step of applying a coating composition to at least one side of a long base film, and a stretching step of stretching the coated base film at least in the width direction, A method for manufacturing a coated film, wherein, in the coating process, multiple regions are provided in which the amount of coating per unit area differs depending on the position in the width direction, and the amount of coating per unit area in the region including both ends in the width direction is greater than the amount of coating per unit area in the region including the center in the width direction.

[0018] [5] The manufacturing method of the coating film according to [4], wherein the coating amount per unit area of the region including both ends is 101 to 150% with respect to the coating amount of the region including the center.

[0019] [6] The manufacturing method of the coating film according to [4] or [5], wherein the base film is unstretched or stretched in a uniaxial direction, and further includes a heat treatment step after the stretching step. [Advantages of the Invention]

[0020] According to the present invention, when forming a coat layer by in-line coating, by adjusting the coating amount during coating according to the position in the width direction, the uniformity of the film thickness in the width direction of the coat layer is high, the appearance of the coat layer is excellent, and a coating film in which the physical properties of various coat layers are stable, and a manufacturing method thereof can be provided. [Brief Description of the Drawings]

[0021] [Figure 1] It is a plan view for explaining the direction of the coating film and the positions of each part. [Figure 2] It is a schematic configuration diagram showing an example of an apparatus for coating a coating composition. [Figure 3A] It is a plan view for explaining an example of each region when coating a coating composition. [Figure 3B] It is a plan view for explaining another example of each region when coating a coating composition. [Embodiments for Carrying Out the Invention]

[0022] Hereinafter, the present invention will be described in detail. For the sake of convenience of explanation, the film formation direction of the film may be referred to as the machine axis direction, the longitudinal direction, the lengthwise direction, the MD direction, and the direction orthogonal to the film formation direction and the thickness direction may be referred to as the width direction, the transverse direction, the TD direction. In addition, various physical property values and the like described in this specification are specifically measured by the methods described in the examples.

[0023] [Coating film] The coating film of the present invention is a roll-shaped coating film having a coating layer on at least one side of a base film, wherein the coating layer is stretched together with the base film at least in the width direction. In other words, in the present invention, the coating layer is formed by in-line coating.

[0024] The stretched state of the base film can be confirmed by the film's birefringence, molecular chain orientation, internal stress, etc. Whether or not it is an inline coating can be confirmed by the stretched state of the coating layer, its adhesion to the base film, the state of the interface, the molecular orientation on the surface of the coating layer, the presence of fillers etc. contained in the coating layer, etc.

[0025] The inventors of this invention have found that in in-line coating, the coating layer is stretched simultaneously with the stretching of the base film, and that uneven stretching of the base film causes variations in the thickness of the coating layer. The reason for the uneven stretching is not clear, but it is thought that variations in the way heat is applied to the film during the preheating process before stretching and during the stretching process are contributing factors. In particular, when stretching in the width direction, the stretching tends to increase from the center toward both ends, and it has been found that the thickness of the coating layer at both ends becomes smaller than at the center. It has been found that this problem is particularly likely to occur when the width of the coating layer is 1250 mm or more. In this invention, by intentionally increasing the amount of coating composition applied to the end regions compared to the central region, it is possible to suppress the reduction in the thickness of the coating layer caused by uneven stretching and to make the thickness of the coating layer uniform across the entire width of the coating layer.

[0026] (Thickness of the coating layer) As shown in Figure 1, the coating film of the present invention is characterized in that, when a reference line L is drawn perpendicular to the longitudinal direction in the width direction, and points C1 and C2 are located on the reference line L and moved 200 mm to the sides in the width direction from the center of the width of the coating layer, point A1 is moved 25 mm toward the center from one end of the coating layer, point A2 is moved 400 mm toward the center from A1, point B1 is moved 25 mm toward the center from the other end of the coating layer, and point B2 is moved 400 mm toward the center from B1, the average film thickness Tc of the coating layer on the reference line L in the central part located between C1 and C2 and the average film thickness Tab of the coating layer on the reference line L at both ends located between A1 and A2 and between B1 and B2 satisfy the relationship |Tab-Tc| / Tc×100≦10. In other words, the ratio (%) of the difference between the average film thickness Tc and the average film thickness Tab is within 10%.

[0027] Having these characteristics is preferable because it prevents deterioration of the appearance of the coating layer across the entire width of the coating layer, and ensures stable performance regardless of the position of the coating film. From this viewpoint, it is preferable that the relationship |Tab-Tc| / Tc×100≦8 is satisfied, more preferably that |Tab-Tc| / Tc×100≦5 is satisfied, and even more preferably that |Tab-Tc| / Tc×100≦3 is satisfied. The value of |Tab-Tc| / Tc×100 is preferable as small as possible, but may be 0.1 or greater, or 0.5 or greater.

[0028] One method to reduce the value of |Tab-Tc| / Tc×100 is to intentionally increase the coating amount in the end regions compared to the central region when applying the coating composition. Specifically, for example, in the process of applying the coating composition to a substrate film using a coating liquid transfer roll, this could involve dividing the coating process into two or more passes to achieve different thicknesses, changing the inclined engraving pattern or cell volume of the coating liquid transfer roll in the width direction, or changing the coating amount by changing the outer diameter of the coating liquid transfer roll. Additionally, methods such as using a guide roll with a face length narrower than the coating width on the side of the moving substrate film opposite the coating liquid transfer roll, or controlling the coating amount using a smoothing roll that contacts the coated surface after coating, are also possible. Details of these methods will be described later.

[0029] When applying a coating composition, if the coating amount is intentionally increased in the areas at both ends compared to the central area, variations in the coating film thickness along the reference line L between reference point A1 and reference point B1 are unavoidable. For this reason, in the present invention, it is preferable to reduce the variation in coating film thickness. When the coating film thickness measured at 150 mm intervals along the reference line L between A1 and B1 is Tmax, the maximum coating thickness is Tmin, and the average coating thickness is Tav, it is preferable that the relationship (Tmax-Tmin) / Tav × 100 ≤ 30 is satisfied. In other words, it is preferable that the variation in the coating film thickness is 30% or less. Reducing the variation in coating film thickness in this way is preferable because it prevents deterioration of the appearance of the coating layer across the entire width of the coating layer, and ensures stable performance regardless of the position of the coating film.

[0030] From this perspective, it is more preferable that the relationship (Tmax-Tmin) / Tav×100 ≤ 28 is satisfied, and even more preferable that the relationship (Tmax-Tmin) / Tav×100 ≤ 25 is satisfied. The value of (Tmax-Tmin) / Tav×100 is preferably as small as possible, but it may be 1 or greater or 5 or greater.

[0031] As a method to reduce the value of (Tmax-Tmin) / Tav×100, as exemplified by the above method which intentionally increases the coating amount in the end regions compared to the central region, examples include determining the boundary between the central region and the end regions at an appropriate position, continuously changing the coating thickness, the cell volume and outer shape of the coating liquid transfer roll, or making the changes small in steps.

[0032] Regarding the overall thickness of the coating layer, it is preferable that the average thickness Tav of the coating layer, measured at the center and at 150 mm intervals on both sides of the reference line L between A1 and B1, is 0.001 to 3 μm. In particular, when it is 0.005 to 1 μm, it is preferable because the effect of increasing the coating amount in the areas at both ends compared to the central area is greater.

[0033] The thickness of the coating layer can be measured from the peak intensities of various elements measured using an X-ray fluorescence spectrometer or from transmission electron microscope images of the cross-section of the coating film. The method for measuring the thickness of the coating layer can be selected depending on the type of coating composition. For example, if the coating composition contains silicone resin, the Si peak intensity measured using an X-ray fluorescence spectrometer can be used, and if the coating composition contains sulfur, the S peak intensity can be used. If the coating composition does not contain elements detectable by X-ray fluorescence, or if the peak intensity is small, the thickness can be calculated by observing the cross-section of the coating layer.

[0034] (Base film) In the present invention, the base film is not particularly limited as long as it is a sheet-like film made of a thermoplastic resin film, and known films can be used. Examples of thermoplastic resins include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene-2,6-naphthalate (PEN); polyamides such as nylon 6 and nylon 6,6; polyolefins such as polyethylene (PE) and polypropylene (PP); and polyacrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA). Other examples include fluorine-based films such as polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE).

[0035] The base film can be manufactured using conventionally known methods and conditions, or methods and conditions accumulated in the industry. For example, the thermoplastic resin can be melt-extruded, rapidly cooled and solidified to form an unstretched film, and then the unstretched film can be stretched and heat-fixed. In this case, the stretching is carried out, for example, at a temperature above the secondary point transition of the thermoplastic resin, and at a magnification of at least 2 times, preferably 3 times, in each of the longitudinal and transverse directions.

[0036] In this invention, for example, a coating composition is applied to a film, which is then dried and stretched. That is, a coating composition is applied to a uniaxially oriented film or an unstretched film, and it is stretched in the longitudinal or transverse direction after or during drying. If necessary, it is further stretched in the longitudinal or transverse direction and then heat-treated to obtain a coated film.

[0037] The above-mentioned base film preferably has a thickness of 10 μm to 200 μm after all stretching is complete, more preferably 12 μm to 150 μm, and more preferably 15 μm to 100 μm. A film thickness of 10 μm or more is preferable because there is no risk of deformation due to heat during film production, processing, or molding. On the other hand, a film thickness of 200 μm or less is preferable because the amount of film to be discarded after use is not excessively large, thus reducing the environmental burden.

[0038] The above-mentioned base film may be a single layer or a multilayer film of two or more layers, but it is preferable to include particles in order to provide the film with good transportability and slipperiness for winding onto a roll. There are no particular restrictions on the type of particles, and known particles can be used, and they may be inorganic or organic particles. Among these, silica particles and / or calcium carbonate particles are preferred.

[0039] In terms of the laminated structure, if one surface layer is designated as layer A, the layer on the opposite side as layer B, and the remaining core layer as layer C, then the layer configuration in the thickness direction can be an A / B or A / C / B laminated structure. Naturally, layer C may consist of multiple layers. Also, surface layers A and B may not contain particles. Particles may be contained in all three layers (A, B, and C), in both layers A and B, or in either layer A or B. If none of the layers contain particles, it is preferable to provide a coating layer containing particles and a binder on one side of the base film to impart slipperiness.

[0040] The coating layer may be provided on the surface of layer A or layer B, or on both the surface of layer A and the surface of layer B. That is, the layer configuration in the thickness direction can be a laminated structure such as coating layer / A / B, coating layer / A / C / B, coating layer / A / B / coating layer, or coating layer / A / C / B / coating layer. When coating layers are provided on both sides, they may be of the same type, or two or more different types of coating layers.

[0041] In one embodiment, the surface of layer A or layer B to which the coating composition is applied may be subjected to surface treatment or an easy-adhesion layer in order to improve adhesion with the coating layer. Examples of surface treatments include plasma treatment, corona discharge treatment, ultraviolet treatment, flame treatment, and electron beam / radiation treatment. Examples of easy-adhesion layers include a layer containing the same resin as the base film, and further containing an antistatic agent, pigment, surfactant, lubricant, antiblocking agent, etc.

[0042] (Coating composition) The coating composition used in the present invention is, for example, used to form functional layers on a film, such as an easy-adhesion layer, a smooth-slip layer, a gas-blocking layer, a moisture-proof layer, an antistatic layer, a scratch-resistant layer, a release layer, and an adhesive layer. To achieve this objective, the coating composition used in the present invention may include, for example, a composition containing a resin component such as silicone as a solid component. In addition to the functional components mentioned above, the solid component of this coating composition may also include a binder component that improves the adhesion between the coating film and the film. Examples of the binder component include polyester resin, polyurethane resin, acrylic resin, epoxy resin, vinyl resin, acrylic-modified polyester, silicone-modified polymer, polyether, and water-soluble resin. Furthermore, it is particularly preferable to use an aqueous coating composition in which the functional components and binder components are dissolved and / or dispersed in water for the coating composition of the present invention.

[0043] In this aqueous coating composition, functional components or binder components such as fillers, surfactants, antioxidants, antistatic agents, colorants, pigments, fluorescent whitening agents, plasticizers, crosslinking agents, lubricants, and ultraviolet absorbers can be added. The solid content concentration of the aqueous coating composition is preferably 0.1 to 30% by mass, and particularly preferably 1 to 20% by mass.

[0044] [Method for manufacturing coated film] The coating film of the present invention can be suitably manufactured by the manufacturing method of the present invention. Specifically, the manufacturing method of the present invention includes a coating step of applying a coating composition to at least one side of a long base film, and a stretching step of stretching the coated base film at least in the width direction, wherein the coating step is characterized by providing a plurality of regions in which the amount of coating per unit area differs depending on the position in the width direction, and the amount of coating per unit area in the region including both ends in the width direction (hereinafter referred to as the "end region") is greater than the amount of coating per unit area in the region including the center in the width direction (hereinafter referred to as the "central region"). Here, the base film is preferably unstretched or stretched in a uniaxial direction, and it is preferable to further include a heat treatment step after the stretching step.

[0045] In the present invention, any known method can be applied to the coating process. For example, conventional methods such as roll coating methods including gravure coating and reverse coating, bar coating methods such as wire bar coating, die coating, spray coating, and air knife coating are used. When the amount of coating in the end regions is greater than the amount of coating in the central region, it is preferable to use the roll coating method from the viewpoint of controlling the amount of coating in each region with high precision.

[0046] Figure 2 is a schematic diagram showing an example of an apparatus for applying a coating composition by the roll coating method. In the present invention, as shown in Figure 2, it is preferable to have a step of applying a coating composition 7 to a base film 1 using a coating liquid transfer roll 3, and it is more preferable to have the coating liquid transfer roll 3 positioned close to the moving base film 1, and a guide roll for stable movement of the base film 1 on the side of the base film 1 opposite to the coating liquid transfer roll 3. It is even more preferable that the guide roll has a first guide roll 2 close to the upstream side of the coating liquid transfer roll and a second guide roll 4 close to the downstream side. At this time, with respect to the direction of travel of the base film 1 (direction of the right arrow), the side on which the conveyed base film 1 is fed to the coating section is the upstream side, and the side on which the base film 1 is sent to the next process after coating is the downstream side.

[0047] In the illustrated example, the first guide roll 2 and the second guide roll 4 are arranged at a distance D from the coating liquid transfer roll 3, and the coating composition 7 is applied to the base film 1 floating between the first guide roll 2 and the second guide roll 4 using the coating liquid transfer roll 3. The coating composition 7 adheres to the coating liquid transfer roll 3, which has cells on its surface, is pulled up from the liquid reservoir 6, and the remaining portion scraped off by the blade 8 is transferred to the base film 1. In addition, a smoothing roll 5 is provided to transfer the coating composition 7 applied to the base film 1 to the smoothing roll 5 and allow it to flow down into the discharge tank 9, thereby controlling the required coating amount. This coating method is preferable because it eliminates the risk of unevenness in the appearance of the coating layer and the physical properties of various coating layers due to vibration of the base film 1 during transport or unevenness in the thickness of the base film 1, resulting in excellent coating uniformity.

[0048] In the present invention, an example of a method for varying the coating amount in each region in the width direction is a method of coating multiple times. Specifically, a method can be described as applying a coating composition to a base film by any coating method to provide a first coating layer, and then continuously applying a second coating layer on the uncoated areas or on the first coating layer. In order to increase the coating amount in the areas at both ends compared to the central area, it is preferable to apply the first coating layer to the central area, then provide a second coating layer with a larger coating amount than the first coating layer at the uncoated ends, or to provide a second coating layer with an arbitrary coating amount at the end position of the first coating layer. The number of coatings can be two or more, and for example, a third coating layer can be provided on the second coating layer or in the uncoated areas at the ends. In this case, it is preferable to sequentially increase the coating amount from the first coating layer in the central area to the third coating layer in the areas at both ends.

[0049] When applying multiple coats, the same coating method may be used, or different coating methods may be used. However, it is preferable to use the same coating composition to achieve uniformity in the physical properties of the coating layer.

[0050] One method for changing the coating amount in the width direction is, for example, when coating using a coating transfer roll, to change the cell volume engraved on the coating transfer roll with respect to the width direction of the coating transfer roll. In this case, it is preferable that the cell volume in the areas at both ends is larger than that in the central area, and it is even more preferable to increase the cell volume in stages from the central area to the areas at both ends.

[0051] When coating using a coating transfer roll, a method can be used in which the outer diameter of the coating transfer roll is varied in the width direction. In this case, by making the outer diameter of the ends smaller than that of the central region, the pressure force between the moving substrate film and the coating transfer roll is reduced, and the gap between them widens, allowing for a larger coating amount in the ends than in the central region.

[0052] When a guide roll is in contact with the side of the base film opposite to the coating transfer roll, it is preferable to make the length of the guide roll smaller than the coating width. By making the length of the guide roll smaller than the coating width, the pressure between the end regions of the base film and the coating transfer roll is reduced, and the gap between them widens, allowing for a larger coating amount in the end regions than in the central region. In this case, the guide rolls whose length is reduced may be both the first guide roll located upstream and the second guide roll located downstream, or it may be just one of them.

[0053] Another method for changing the coating amount in the width direction is to use a smoothing roll. For example, after applying a first coating layer with a uniform coating amount in the width direction, a smoothing roll with a surface length smaller than the coating width can be placed on the same surface as the first coating layer and in contact with the central region. By transferring the liquid to the smoothing roll, the coating amount in the central region can be reduced.

[0054] Figures 3A and 3B show plan views illustrating multiple regions where the coating amount per unit area differs depending on the position in the width direction when applying the coating composition. Figure 3A shows an example of a region divided into three parts: a central region and two end regions, while Figure 3B shows an example of a region divided into five parts, with an intermediate region between the central region and the end regions. The number of divisions may be even greater, such as seven or nine divisions. When dividing, it is preferable that the divided regions are symmetrical with respect to the center line.

[0055] For example, as shown in Figure 3A, if there are three divided end regions / central region / end regions, it is preferable that each end region is in the range of 1% to 35% from the outermost position of the coating width toward the center, when the total length of the coating width is considered to be 100%. In that case, it is preferable that the central region is in the range of 98% to 30% from the center position of the coating width toward both ends.

[0056] Furthermore, as shown in Figure 3B, when there are five divided end regions / intermediate regions / central regions / intermediate regions / end regions, it is preferable that each end region is in the range of 1% to 25% from the outermost position of the coating width toward the center, when the total length of the coating width is considered to be 100%. It is preferable that each intermediate region is in the range of 1% to 25% from the central end position of each end region toward the center. In that case, it is preferable that the central region is in the range of 96% to 30% from the center position of the coating width toward both ends.

[0057] Furthermore, even when there are many divisions, multiple intermediate regions can be provided where the amount of coating per unit area differs in stages depending on the position in the width direction.

[0058] The ranges of the end regions, the central region, and, if an intermediate region is provided, are preferably determined by the stretching conditions of the base film. That is, it is preferable to calculate the actual stretching ratio in the width direction of the coating layer from the thickness distribution in the width direction before stretching and the thickness distribution in the width direction after stretching, and to determine what percentage of the outermost position of the coating width the coating amount should be changed.

[0059] The amount of coating applied to both end regions and the central region, as well as the amount of coating applied to the intermediate region if one is provided, is preferably determined by the stretching conditions of the base film. Specifically, it is preferable to calculate the actual stretching ratio from the thickness distribution in the width direction before and after stretching of the base film, and to determine what percentage increase in the coating amount in the end regions should be compared to the central region.

[0060] In this invention, the coating amount per unit area is 0.1 to 30 g / m² in the central region. 2 Preferably, the range is 1 to 20 g / m 2 It is more preferable that the amount of coating is within this range. With such a coating amount, the physical instability due to uneven coating or incomplete curing of the coating composition is suppressed, and the physical properties of the various coating layers tend to be stable throughout the entire width direction, making the present invention particularly effective.

[0061] In this invention, the amount of coating per unit area in the region including both ends is preferably 101 to 150% and more preferably 103 to 130% of the amount of coating in the region including the center. By providing multiple regions in which the amount of coating per unit area differs depending on the position in the width direction, it is possible to obtain a coating film with high uniformity of film thickness in the width direction of the coating layer, excellent appearance of the coating layer, and stable physical properties of various coating layers.

[0062] Therefore, when there are three divided regions, a central region and three more regions, the coating amount in the end regions is preferably 1% to 50% greater than the coating amount in the central region, and preferably 3% to 30% greater.

[0063] Furthermore, if the area is divided into five or more sections and has intermediate regions, it is preferable to adopt a coating amount for the intermediate region that is midway between the coating amounts for the end regions and the coating amount for the central region (for example, the average coating amount of both).

[0064] In this invention, after applying the coating composition, it is preferably stretched transversely during drying, but if necessary, it can be further stretched in the longitudinal and / or transverse directions and then heat-treated. At this time, the film thickness of the coating layer after drying, solidification, and stretching is preferably 0.001 to 3 μm, and particularly preferably 0.005 to 1 μm.

[0065] The outer diameter of the coating liquid transfer roll is preferably in the range of 1 mm to 150 mm, and more preferably in the range of 5 mm to 100 mm. A diameter of 1 mm or more is preferable because it facilitates engraving on the outer circumference. A diameter of 150 mm or less is preferable because it reduces the contact area between the base film and the coating liquid transfer roll, thereby suppressing scratches on the base film due to friction. It is also preferable because it suppresses liquid turbulence in the liquid transfer area, which does not risk deteriorating the appearance of the coating layer.

[0066] It is preferable to apply the coating liquid while the transfer roll is rotating. From the viewpoint of coating uniformity, it is preferable to apply the coating at the same speed as the transport speed of the base film or at a speed difference, and when a speed difference is applied, the rotation speed is preferably 1% to 200% of the transport speed of the base film.

[0067] The rotation speed of the coating transfer roll can be set arbitrarily according to the operating conditions, either in the opposite direction (reverse rotation) or the same direction (forward rotation) as the substrate film is moving.

[0068] There are no particular limitations on the method of supplying the coating composition to the coating transfer roll, and known methods can be used. For example, methods include filling a predetermined amount of coating composition using a slot die, fountain nozzle, spray, etc., or filling by bringing the coating transfer roll into contact with a liquid reservoir provided in a chamber case or the like. It is preferable to scrape off any excess coating liquid with a doctor blade or the like and measure the filled coating liquid, but coating can also be performed without a doctor blade.

[0069] In the present invention, the preheating step is a step of heating the film to a predetermined temperature, for example, a temperature above the glass transition temperature, in order to dry the coating composition and stretch the base film. For example, if the base film is a polyester film, the drying temperature may be 60°C or more and 140°C or less, for example, 60°C or more and 130°C or 60°C or more and 125°C or less. A temperature of 60°C or higher is preferable because it prevents insufficient drying of the coating composition and avoids the risk of film breakage when stretching the polyester film in the stretching step. A temperature of 140°C or lower prevents rapid drying of the coating composition and suppresses aggregation and gelation of binder resin and particles in the composition, resulting in excellent coating uniformity and suppression of deterioration of the appearance of the coating layer.

[0070] In the present invention, the stretching step is a step of stretching the base film and the coating layer. For example, when the base film is a polyester film, the stretching temperature in the stretching step is, for example, 60°C to 160°C, preferably 60°C to 150°C, and preferably 70°C to 150°C from the viewpoint of stretchability. The stretching ratio is preferably 1 to 8 times, and preferably 2 to 6 times from the viewpoint of uniform stretching without unevenness. Stretching can be performed in either the longitudinal direction or the width direction, but it is preferable to have a step of stretching in at least the width direction after coating the coating composition.

[0071] In the present invention, it is preferable to have a heat-setting step in which the coating film is heat-treated after stretching to complete crystal orientation in order to impart dimensional stability and mechanical properties to the coating film. For example, when the base film is a polyester film, the temperature of the heat-setting step is preferably as high as possible to promote crystallization of the polyester film and curing of the coating composition, but it is preferable that the temperature is below the melting point of polyester. Specifically, it is preferably 180°C or higher and 250°C or lower, and more preferably 200°C or higher and 240°C or lower. A temperature of 180°C or higher is preferable because the curing of the coating composition proceeds sufficiently and the dimensional stability and mechanical properties of the polyester film are sufficient. A temperature of 250°C or lower is preferable because the crystals of the polyester film do not melt and a coating film with excellent flatness can be obtained.

[0072] After each process is completed, the resulting coating film is wound into a roll. Before or after winding into a roll, slitting or other processes may be performed to remove unwanted portions, including uncoated areas. [Examples]

[0073] The present invention will be described in more detail below using examples, but the present invention is not limited in any way by these examples. The characteristic values ​​used in the present invention were evaluated using the following method.

[0074] (Sample for measuring coating layer thickness) As shown in Figure 1, a reference line L is drawn in the width direction of the coating film. Points C1 and C2 are located on the reference line L and are 200 mm to the left and right of the center of the width of the coating layer. Point A1 is 25 mm towards the center from one end of the coating layer, and point A2 is 400 mm further towards the center from A1. Point B1 is 25 mm towards the center from the other end of the coating layer, and point B2 is 400 mm further towards the center from B1.

[0075] To measure the average film thickness Tc in the central part, samples were prepared by cutting out 10 strips at equal intervals from the central reference line L located between C1 and C2. Additionally, to measure the average film thickness Tab at both ends, samples were prepared by cutting out 10 strips at equal intervals from the reference lines L located between A1 and A2 and between B1 and B2. To measure the maximum film thickness Tmax, minimum film thickness Tmin, and average film thickness Tav, samples were prepared by cutting out strips at 150mm intervals from the central and both sides of the reference line L between A1 and B1.

[0076] (Method for measuring the thickness of the coating layer) The sample prepared as described above was embedded in resin, and the section was cut using an ultramicrotome at a position along the reference line L to obtain ultrathin sections. Subsequently, the film cross-section was observed using a JEOL JEM2100 transmission electron microscope under an acceleration voltage of 200kV, and the film thickness of each part of the coating layer was measured from the observed TEM images.

[0077] (Ratio of the difference between average film thickness Tc and average film thickness Tab) The average film thickness was calculated for samples cut into strips at 10 equally spaced points from the central reference line L, and this was defined as the average film thickness Tc (μm). Additionally, the average film thickness was calculated for samples cut into strips at 5 equally spaced points each from the reference lines L at both ends, between A1 and A2, and between B1 and B2, for a total of 10 strips, and this was defined as the average film thickness Tab (μm). The ratio of the difference between the average film thickness Tc and the average film thickness Tab was calculated using the following formula. Ratio of difference (%) = |Tab - Tc| / Tc × 100

[0078] (Variations in coating thickness) For samples cut into strips at 150 mm intervals along the reference line L between A1 and B1, the maximum film thickness Tmax, minimum film thickness Tmin, and average film thickness Tav were determined. The average film thickness Tav was calculated by taking the number average of all the film thicknesses. The variation in the thickness of the coating layer was determined using the following formula. Film thickness variation (%) = (Tmax - Tmin) / Tav × 100

[0079] (Appearance of the coating layer) After all stretching was completed, a sample for visual inspection was cut from the coating film roll obtained by winding it onto a roll. The appearance of the coating layer of the obtained sample was visually observed. The visual inspection was performed over an area of ​​the total width of the coating layer × 1 m in the longitudinal direction, and was evaluated according to the following criteria. The coating defects confirmed at this time refer to coating-related defects such as uneven coating, coating repellency, and coating streaks. ○: The coating layer was inspected under white light in a light-shielded darkroom, and no coating defects were visible. △: The coating layer's appearance is inspected under white light in a light-shielded darkroom, and coating defects are visible. ×: The coating defect was visible during the visual inspection in a manufacturing environment that was not shielded from light.

[0080] (Coating amount)

[0081] After applying the coating composition to a moving substrate film, the coating amount at a position passed within 1 second was measured using an optical interferometer. The obtained reflectance spectrum was converted to a power spectrum by FFT periodic analysis, and the film thickness was calculated. At this time, the film thickness value calculated using a refractive index of 1.35 was adopted as the coating amount.

[0082] (Urethane resin aqueous dispersion) In a four-necked flask equipped with a stirrer, a Liebig condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 27.5 parts by mass of hydrogenated m-xylylene diisocyanate, 6.5 parts by mass of dimethylolpropanoic acid, 60 parts by mass of polyhexamethylene carbonate diol with a number average molecular weight of 1800, 6 parts by mass of neopentyl glycol, and 84.00 parts by mass of acetone as a solvent were added. The mixture was stirred at 75°C under a nitrogen atmosphere for 3 hours, and it was confirmed that the reaction solution reached the predetermined amine equivalent. Next, 5 parts by mass of trimethylolpropane was added, and the mixture was stirred at 75°C under a nitrogen atmosphere for 1 hour, and it was confirmed that the reaction solution reached the predetermined amine equivalent. After the reaction solution was cooled to 40°C, 5.17 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, in a reaction vessel equipped with a homodisperser capable of rapid stirring, 450 g of water was added, the temperature was adjusted to 25°C, and the mixture was stirred for 2000 min. -1 While stirring and mixing, the polyurethane prepolymer solution was added and dispersed in water. Then, under reduced pressure, a urethane resin aqueous dispersion with a solid content of 34% by mass was prepared by removing some of the acetone and water.

[0083] (Blocked isocyanate aqueous dispersion) In a flask equipped with a stirrer, thermometer, and reflux condenser, 66.04 parts by mass of a polyisocyanate compound having an isocyanurate structure derived from hexamethylene diisocyanate (Duranate TPA, manufactured by Asahi Kasei Chemicals) and 17.50 parts by mass of N-methylpyrrolidone were added dropwise to 95 parts by mass of 3,5-dimethylpyrazole (dissociation temperature: 120°C, boiling point: 218°C). The mixture was held at 70°C for 1 hour under a nitrogen atmosphere. Subsequently, 30 parts by mass of dimethylolpropanoic acid were added dropwise. After measuring the infrared spectrum of the reaction solution and confirming the disappearance of the absorption of the isocyanate group, 5.59 parts by mass of N,N-dimethylethanolamine and 132.5 parts by mass of water were added to obtain a block polyisocyanate aqueous dispersion with a solid content of 40% by mass. The number of functional groups of this block isocyanate crosslinking agent is 4, and the NCO equivalent is 280.

[0084] (Polyester aqueous dispersion) In a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser, 194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, 14.8 parts by mass of dimethyl-5-sodium sulfoisophthalate, 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate were charged, and a transesterification reaction was carried out at a temperature of 160°C to 220°C for 4 hours. The temperature was then raised to 255°C, the reaction system was gradually depressurized, and the reaction was carried out under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymerized polyester resin. The obtained copolymerized polyester resin was pale yellow and transparent. The reduced viscosity of the copolymerized polyester resin was measured to be 0.70 dl / g. The glass transition temperature determined by DSC was 40°C.

[0085] In a reactor equipped with a stirrer, thermometer, and reflux device, 15 parts by mass of the polyester resin and 15 parts by mass of ethylene glycol n-butyl ether were placed and heated at 110°C, and the resin was dissolved by stirring. After the resin was completely dissolved, 70 parts by mass of water were 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 aqueous polyester dispersion with a solid content of 15% by mass.

[0086] (Example of manufacturing of coating composition 1) Coating composition 1 (total solids concentration 10%) was prepared by mixing the following coating agent with a mixed solvent of water and isopropanol, resulting in a solids mass ratio of 25 / 26 / 49 for the urethane resin aqueous dispersion / block isocyanate aqueous dispersion / polyester aqueous dispersion. 3.55 parts by mass of urethane resin aqueous dispersion. Crosslinking agent (blocked isocyanate aqueous dispersion) 3.16 parts by mass Polyester aqueous dispersion 16.05 parts by mass Particles 0.47 parts by mass (Dry-processed silica with an average particle size of 200 nm, solid content concentration of 3.5% by mass) Particles 1.85 parts by mass (Silica sol with average particle size of 40-50 nm, solid content concentration of 30% by mass) Surfactant 0.35 parts by mass (Silicone-based, solid content concentration 10% by mass)

[0087] (Vinyl group-containing silicone emulsion: a-1) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 98% by mass of alkenyl group-containing silicone (o=125, k=4, number average molecular weight 9756) represented by chemical formula (a-1) and 2% by mass of polyoxyethylene lauryl ether (manufactured by Kao Corporation, product name "Emulgen 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain a vinyl group-containing silicone emulsion (a-1) with a solid content of 20% by mass. Furthermore, the emulsion particle size was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0088] [ka]

[0089] (Hydrogen group-containing silicone emulsion: b-1) Using an emulsifying device capable of stirring the entire contents of a container (manufactured by N.P. Lab Co., Ltd., device name "Ultra Planetary Mixer"), a raw material consisting of 98% by mass of hydrogen group-containing silicone (l=40, n=40, number average molecular weight 5522) represented by chemical formula (b-1) and 2% by mass of polyoxyethylene lauryl ether (manufactured by Kao Corporation, product name "Emulgen 109P") as a surfactant was mechanically emulsified in an aqueous medium to obtain a hydrogen group-containing silicone emulsion (b-1) with a solid content of 20% by mass. Furthermore, the emulsion particle size was adjusted by adjusting the stirring speed and stirring time during emulsification.

[0090] [ka]

[0091] (Example of manufacturing of coating composition 2) Coating composition 2 with a solid content of 5% was prepared by mixing 100 parts by weight of vinyl group-containing silicone emulsion (a-1), 12 parts by weight of hydrogen group-containing silicone emulsion (b-1), platinum-based catalyst emulsion (manufactured by Shin-Etsu Chemical Co., Ltd., product name "CAT-PM-10A") with water in a composition ratio of 100 ppm of platinum element relative to the vinyl group-containing silicone, and crosslinking reaction inhibitor (1-ethynylcyclohexanol) in a composition ratio of 150 ppm relative to the total weight of the coating composition.

[0092] <Example 1> As the film raw material polymer, PET resin pellets with an intrinsic viscosity (solvent: phenol / tetrachloroethane = 60 / 40) of 0.62 dl / g and substantially free of particles were melted in an extruder and extruded from a die at approximately 280°C. The pellets were then cooled in a cooling drum by a conventional method to obtain an unstretched film. Next, the unstretched film was stretched 3.6 times in the longitudinal direction at 100°C to obtain a uniaxially oriented PET film. Then, using a coating liquid transfer roll with a diameter of 50 mm, coating composition 1 was applied in the opposite direction to the running direction of the base film (reverse rotation) to a coating amount of 4.0 μm and a coating width of 800 mm to provide a first coating layer. Subsequently, a second coating layer with a coating width of 100 mm was applied to both ends of the base film so as to be continuous with the first coating layer, on the uncoated portions at both ends. The second coating layer was applied with a coating amount of 5.0 μm of coating composition 1, and the total coating width of the first and second coating layers was 1000 mm. Next, the coated film was dried at 115°C, stretched 4.0 times in the transverse direction at 145°C, and then heat-set at 230°C for approximately 10 seconds to obtain a roll of coated film (thickness 100 μm) as shown in Table 1. The coated film was unwound from the obtained roll and evaluated as described in Table 1. The average film thickness Tc of the coating layer in the central part (C1-C2) was 0.1 μm.

[0093] <Example 2> A roll of coated film was obtained in the same manner as in Example 1, except that the coating width of the second coating layer was set to 50 mm and the coating amount to 4.5 μm, and a third coating layer was applied to the uncoated positions at both ends so as to be continuous with the second coating layer, with the coating width of the third coating layer set to 50 mm and the coating amount to 5.0 μm. The second and third coating layers were provided by applying coating composition 1. The total coating width of the first, second, and third coating layers at this time was 1000 mm.

[0094] <Example 3> Coating composition 1 was applied to a uniaxially oriented film obtained in the same manner as in Example 1, using a coating transfer roll with modified cell volumes at both ends, such that the coating amount was 5.0 μm in the 100 mm at both ends of the coating width and 4.0 μm in the central region, for a coating width of 1000 mm. Next, this coated film was dried at 115°C, stretched 4.0 times in the transverse direction at 145°C, and then heat-set at 230°C for approximately 10 seconds to obtain a roll of coated film (thickness 100 μm) shown in Table 1.

[0095] <Example 4> A coating film roll as described in Table 1 was obtained in the same manner as in Example 3, except that a coating liquid transfer roll was used in which the cell volume per unit area was uniform, the outer diameter of the 100 mm at both ends of the coating width was 40 mm, the outer diameter of the central region was 50 mm, and the outer diameter gradually changed in the intermediate region, for a coating width of 1000 mm. Furthermore, as the outer diameter of the coating liquid transfer roll decreased, the pressure on the film decreased, and the coating amount increased.

[0096] <Example 5> A roll of the coating film described in Table 1 was obtained in the same manner as in Example 4, except that the outer diameter of the coating liquid transfer roll was 50 mm in total width, and the face lengths of the first and second guide rolls adjacent to the opposite side of the coating liquid transfer roll via the base film were 750 mm. Note that as the face length of the guide rolls decreased, the pressure on the film decreased, and the coating amount increased.

[0097] <Example 6> Using a coating transfer roll with an outer diameter of 50 mm in total width, coating composition 1 was applied to a uniaxially oriented film obtained in the same manner as in Example 1, with a coating width of 1000 mm and a coating amount of 5.0 μm, to form a first coating layer. Then, a smoothing roll with a face length of 750 mm was placed in the center of the first coating layer and the coating was transferred to the smoothing roll so that the coating amount in the central area was 4.0 μm. Next, this coated film was dried at 115°C, stretched 4.0 times laterally at 145°C, and then heat-set at 230°C for about 10 seconds to obtain a roll of coated film (thickness 100 μm) as shown in Table 1.

[0098] <Example 7> Polyethylene terephthalate ([η]=0.63 dl / g, Tg=78℃) containing 0.25 mass% of calcium carbonate particles with an average particle size of 0.6 μm was melted in an extruder, extruded through a die, and cooled in a cooling drum by conventional methods to obtain an unstretched film. Next, it was stretched 3.2 times in the longitudinal direction at 100℃ to obtain a uniaxially oriented film. Then, using a coating liquid transfer roll with a diameter of 50 mm, coating composition 2 was applied in the opposite direction to the running direction of the base film (reverse rotation) to a coating amount of 4.0 μm and a coating width of 800 mm to provide a first coating layer. Subsequently, a second coating layer with a coating width of 100 mm was applied to the uncoated areas at both ends of the base film, continuous with the first coating layer. The second coating layer was applied with a coating amount of 5.0 μm of coating composition 2, and the total coating width of the first and second coating layers was 1000 mm. Next, the coated film was dried at 115°C, stretched 4.5 times in the transverse direction at 145°C, and then heat-set at 230°C for approximately 10 seconds to obtain a roll of coated film (thickness 25 μm) as shown in Table 1. The coated film was unwound from the obtained roll and evaluated as described in Table 1. The average film thickness Tc of the coating layer in the central part (C1-C2) was 0.044 μm.

[0099] <Example 8> A roll of coated film was obtained in the same manner as in Example 7, except that the coating width of the second coating layer was set to 50 mm and the coating amount to 4.5 μm, and a third coating layer was applied to the uncoated areas at both ends so as to be continuous with the second coating layer, with the coating width of the third coating layer set to 50 mm and the coating amount to 5.0 μm. The second and third coating layers were provided by applying coating composition 2. The total coating width of the first, second, and third coating layers at this time was 1000 mm.

[0100] <Example 9> Coating composition 2 was applied to a uniaxially oriented film obtained in the same manner as in Example 7, using a coating transfer roll with modified cell volumes at both ends, such that the coating amount was 5.0 μm in the 100 mm at both ends of the coating width and 4.0 μm in the central region, for a coating width of 1000 mm. Next, this coated film was dried at 115°C, stretched 4.5 times in the transverse direction at 145°C, and then heat-set at 230°C for approximately 10 seconds to obtain a roll of coated film (thickness 25 μm) shown in Table 1.

[0101] <Example 10> A roll of the coating film described in Table 1 was obtained in the same manner as in Example 9, except that a coating liquid transfer roll was used in which the cell volume per unit area was uniform, the outer diameter of the 100 mm at both ends of the coating width was 40 mm, the outer diameter of the central region was 50 mm, and the outer diameter gradually changed in the intermediate region, for a coating width of 1000 mm.

[0102] <Example 11> A roll of the coating film described in Table 1 was obtained in the same manner as in Example 10, except that the outer diameter of the coating liquid transfer roll was 50 mm in total width, and the face length of the first guide roll and the second guide roll adjacent to the opposite side of the coating liquid transfer roll via the base film was 750 mm.

[0103] <Example 12> Using a coating transfer roll with an outer diameter of 50 mm in total width, the coating composition 2 was applied to a uniaxially oriented film obtained in the same manner as in Example 7, with a coating width of 1000 mm and a coating amount of 5.0 μm, to form the first coating layer. Then, a smoothing roll with a face length of 750 mm was placed in the center of the first coating layer and the coating was transferred to the smoothing roll so that the coating amount in the central area was 4.0 μm. Next, this coated film was dried at 115°C, stretched 4.5 times in the transverse direction at 145°C, and then heat-set at 230°C for about 10 seconds to obtain a roll of coated film (thickness 25 μm) as shown in Table 1.

[0104] <Comparative Example 1> Using a coating transfer roll with an outer diameter of 50 mm in total width, coating composition 1 was applied to a uniaxially oriented film obtained in the same manner as in Example 1, with a coating width of 1000 mm and a coating amount of 4.0 μm. Next, this coated film was dried at 115°C, stretched 4.0 times in the transverse direction at 145°C, and then heat-set at 230°C for approximately 10 seconds to obtain a roll of coated film (thickness 100 μm) as shown in Table 1.

[0105] <Comparative Example 2> Using a coating transfer roll with an outer diameter of 50 mm in total width, coating composition 2 was applied to a uniaxially oriented film obtained in the same manner as in Example 7, with a coating width of 1000 mm and a coating amount of 4.0 μm. Next, this coated film was dried at 115°C, stretched 4.5 times in the transverse direction at 145°C, and then heat-set at 230°C for approximately 10 seconds to obtain a roll of coated film (thickness 25 μm) as shown in Table 1.

[0106] <Comparative Example 3> A coating composition 2 was applied to one surface of a 25 μm thick biaxially oriented polyester film (Toyobo Co., Ltd., Toyobo Ester Film E5100) using reverse gravure printing to achieve a coating width of 1000 mm and a coating thickness of 4.0 μm. The film was then dried at 160°C for 60 seconds and wound into a roll to obtain a coated film roll. The coated film was unwound from the resulting coated film roll and evaluated as described in Table 1.

[0107] [Table 1]

[0108] As shown in Table 1, in Examples 1 to 12, by changing the amount of coating in the width direction using various methods, it was possible to suppress the reduction in the thickness of the coating layer due to uneven stretching of the base film that occurs near both ends during stretching, and to obtain a release film with a uniform coating layer thickness throughout the entire coating layer.

[0109] In contrast, in Comparative Examples 1 and 2, coating composition 1 or coating composition 2 was applied with a uniform coating amount in the width direction. As a result, the thickness of the coating layer at both ends decreased due to uneven stretching of the base film, resulting in an uneven coating layer thickness.

[0110] In Comparative Example 3, a coated film was obtained using an offline coating method. To prevent deterioration of flatness due to thermal deformation of the base film, it was not possible to apply heat above 160°C, and the curing of coating composition 2 did not proceed sufficiently. As a result, the obtained release film experienced transfer of the coating layer to the transport roll and back transfer when wound onto the roll, resulting in deterioration of the uniformity of the coating layer thickness and the appearance of the coating layer. [Industrial applicability]

[0111] The coating film produced by the manufacturing method of the present invention has a uniform coating layer thickness, excellent coating layer appearance, stable coating properties, and can be suitably used in various applications. [Explanation of Symbols]

[0112] 1: Base film 2: First guide role 3: Coating liquid transfer roll 4: Second Guide Role 7: Coating composition

Claims

1. A roll-shaped coating film having a coating layer on at least one side of a base film, The coating layer is stretched together with the base film at least in the width direction, The width of the aforementioned coating layer is 1250 mm or more. When a reference line L is drawn in the width direction, and points C1 and C2 are located on the reference line L and moved 200 mm to the left and right of the center of the width of the coating layer, and point A1 is located on the reference line L and moved 25 mm toward the center from one end of the coating layer, and point A2 is located 400 mm toward the center from A1, and point B1 is located on the reference line L and moved 25 mm toward the center from the other end of the coating layer, and point B2 is located 400 mm toward the center from B1, A coating film in which the average thickness Tc of the coating layer on the central reference line L located between C1 and C2, and the average thickness Tab of the coating layer on the reference lines L at both ends located between A1 and A2 and between B1 and B2, satisfy the relationship |Tab - Tc| / Tc × 100 ≤ 10.

2. The coating film according to claim 1, wherein, when the thickness of the coating layer measured at 150 mm intervals on a reference line L between A1 and B1, the maximum thickness is Tmax, the minimum thickness is Tmin, and the average thickness is Tav, the relationship (Tmax - Tmin) / Tav × 100 ≤ 30 is satisfied.

3. The coating film according to claim 1 or 2, wherein the average film thickness Tav of the coating layer, measured at 150 mm intervals on a reference line L between A1 and B1, is 0.005 μm or more and 1 μm or less.

4. The process includes a coating step of applying a coating composition to at least one side of a long base film, and a stretching step of stretching the coated base film at least in the width direction, A method for manufacturing a coated film, wherein, in the coating process, multiple regions are provided in which the amount of coating per unit area differs depending on the position in the width direction, and the amount of coating per unit area in the region including both ends in the width direction is greater than the amount of coating per unit area in the region including the center in the width direction.

5. A method for manufacturing a coated film according to claim 4, wherein the amount of coating per unit area of ​​the region including both ends is 101 to 150% of the amount of coating in the region including the central part.

6. The method for manufacturing a coating film according to claim 4 or 5, wherein the base film is unstretched or uniaxially stretched, and the method further includes a heat treatment step after the stretching step.

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