Polyester film, resin film

Abstract

Provided is a film in which functions such as adhesiveness are exhibited by removing protrusions on the surface. 【Solution means】A polyester film that satisfies the following conditions in the height image and elastic modulus image of a 30-μm square field of view measured by AFM before and after water immersion treatment for at least one surface A. 0.1 ≦ E A2 / E A1 <1.0 0.1 ≦ E B1 / E B2 <1.0 E A1 : The average elastic modulus (GPa) of the region where the height before water immersion treatment exceeds 5 nm from the average plane of the measurement region E A2 : The average elastic modulus of the region where the height before water immersion treatment is less than -5 nm from the average plane of the measurement region E B1 : The average elastic modulus of the region where the height after water immersion treatment exceeds 5 nm from the average plane of the measurement region E B2 : The average elastic modulus of the region where the height after water immersion treatment is less than -5 nm from the average plane of the measurement region <Water immersion treatment conditions> Immerse a film with a size of 1 × 1 cm in 20 g of pure water, perform ultrasonic treatment at an output of 130 W for 60 minutes using an ultrasonic cleaner with the temperature controlled at 23°C, and then leave it to stand and dry at room temperature for 24 hours

Description

[Technical Field]

[0001] This invention relates to a polyester film that exhibits adhesive properties through removal treatments such as water immersion, and is used in various applications such as surface protection. [Background technology]

[0002] Currently, functional films with various functions are widely known. Functional films are mainly films on which a functional layer exhibiting various functions is provided. Examples include films with functions such as adhesiveness, conductivity, sliding properties, antibacterial properties, and heat sealability. In order to exhibit these functions, contact with the object is necessary. For example, an adhesive film intended for surface protection (Patent Document 1) can prevent scratches during transportation, storage, and processing, and prevent the adhesion of dust and dirt by being bonded to the object to be protected. In the case of an antibacterial film (Patent Document 2), it is known that the effect is obtained when the object comes into contact with antibacterial particles. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-64540 [Patent Document 2] Japanese Patent Publication No. 2024-140733 [Overview of the project] [Problems that the invention aims to solve]

[0004] Adhesive films have a release liner to prevent them from exhibiting their function until they are bonded to the object they protect. However, peeling off the release liner can cause static electricity, which can lead to misalignment during bonding. Antibacterial films may lose their functionality if antibacterial particles on the film surface fall off during transportation, storage, or processing. For these reasons, there has been a need to develop functional films that have a mechanism to protect the functional layer, that can be easily removed, and that do not generate static electricity during the removal process.

[0005] Therefore, the objective of the present invention is to provide a film that exhibits functions such as adhesiveness by removing surface protrusions. [Means for solving the problem]

[0006] To solve the above problems, a preferred embodiment of the present invention has the following configuration. 1. A polyester film that satisfies the following conditions in the height image and elastic modulus image of a 30 μm square field of view measured by AFM before and after water immersion treatment on at least one surface A. 0.1 ≤ E A2 / E A1 < 1.0 0.1 ≤ E B1 / E B2 < 1.0 E A1 : The average modulus of elasticity (GPa) of the region where the height before water immersion treatment is 5 nm above the average surface of the measurement area. E A2 : The average modulus of elasticity (GPa) of the region where the height before water immersion treatment is less than -5 nm from the average surface of the measurement area. E B1 : The average modulus of elasticity (GPa) of the region where the height after water immersion treatment exceeds 5 nm from the average surface of the measurement area. E B2 : The average modulus of elasticity (GPa) of the region where the height after water immersion treatment is less than -5 nm from the average surface of the measurement area. <Water immersion treatment conditions> The film is sampled to a size of 1 cm x 1 cm, immersed in 20 g of pure water, and ultrasonically treated for 60 minutes at 130 W output using an ultrasonic cleaner heated to 23°C. After that, it is allowed to dry at room temperature for 24 hours. 2. A polyester film in which, for at least one surface A, the spacing of protrusions D1 before water immersion treatment and the spacing of protrusions D2 after water immersion treatment satisfy the following conditions. 0.0 ≤ D1 / D2 ≤ 0.8 <Water immersion treatment conditions> The film is sampled to a size of 1 cm x 1 cm, immersed in 20 g of pure water, and ultrasonically treated for 60 minutes at 130 W output using an ultrasonic cleaner heated to 23°C. After that, it is allowed to dry at room temperature for 24 hours. 3. The polyester film according to 1. or 2., wherein, in the height image of the 30 μm square field of view measured with AFM on surface A, the area ratio RA of the region whose height is 5 nm above the average plane of the measurement area is 5% or more and 40% or less. 4. A polyester film according to any of 1 to 3, wherein, in a 113 μm square field of view measured with a white light interference microscope on surface A, the maximum peak height Sp is 10 nm or more and 1000 nm or less. 5. A polyester film according to any of 1 to 4, wherein, in a 113 μm square field of view measured with a white light interference microscope on surface A, the maximum valley depth Sv is 10 nm or more and 1000 nm or less. 6. A polyester film according to any of 1 to 5, wherein, in a 113 μm square field of view measured with a white light interference microscope on surface A, the arithmetic mean height Sa is 2 nm or more and 300 nm or less, and the aspect ratio Str of the surface properties is 0.1 or more and 0.5 or less. 7. The polyester film described in 1., wherein the projection spacing D1 before water immersion treatment and the projection spacing D2 after water immersion treatment satisfy the following conditions for surface A. 0.0 ≤ D1 / D2 ≤ 0.8 <Water immersion treatment conditions> The film is sampled to a size of 1 cm x 1 cm, immersed in 20 g of pure water, and ultrasonically treated for 60 minutes at 130 W output using an ultrasonic cleaner heated to 23°C. After that, it is allowed to dry at room temperature for 24 hours. 8. In the height image of a 30-μm square field of view obtained by AFM measurement of surface A, the polyester film according to any one of 1. to 7., wherein the main component of the region where the height exceeds 5 nm from the average plane of the measurement region is a water-soluble resin. 9. In the height image of a 30-μm square field of view obtained by AFM measurement of surface A, the polyester film according to any one of 1. to 8., wherein the main component of the region where the height is less than -5 nm from the average plane of the measurement region is an adhesive resin. 10. The polyester film according to 9., which is used for the purpose of placing an adherend so as to contact surface A and protecting the adherend. 11. The polyester film according to 10., which is used by adhering surface A and the adherend by performing a water immersion treatment after placing the adherend on surface A. 12. A resin film that satisfies the following conditions in the height image and elastic modulus image of a 30-μm square field of view obtained by AFM measurement of at least one surface A before and after the removal treatment. 0.1 ≦ E C2 / E C1 < 1.0 0.1 ≦ E D1 / E D2 < 1.0 E C1 : The average elastic modulus (GPa) of the region where the height before the removal treatment exceeds 5 nm from the average plane of the measurement region E C2 : The average elastic modulus (GPa) of the region where the height before the removal treatment is less than -5 nm from the average plane of the measurement region E D1 : The average elastic modulus (GPa) of the region where the height after the removal treatment exceeds 5 nm from the average plane of the measurement region E D2 : The average elastic modulus (GPa) of the region where the height after the removal treatment is less than -5 nm from the average plane of the measurement region

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a film whose surface characteristics such as adhesiveness change according to a removal treatment such as a water immersion treatment.

Brief Description of the Drawings

[0008] [Figure 1] This is a conceptual diagram showing a cross-section of surface A of an example of the polyester film of the present invention before water immersion treatment. [Figure 2] This is a conceptual diagram showing a cross-section of surface A after water immersion treatment in an example of the polyester film of the present invention. [Figure 3] This is a conceptual diagram showing a cross-section of surface A before the removal treatment in an example of the resin film of the present invention. [Figure 4] This is a conceptual diagram showing a cross-section of surface A after removal treatment in an example of the resin film of the present invention. [Modes for carrying out the invention]

[0009] A preferred embodiment of the present invention will be described in detail below with specific examples.

[0010] The polyester film of the present invention, for at least one surface A, has an average elastic modulus of E in the height image and elastic modulus image of the 30 μm square field of view measured by AFM, where the height of the region is 5 nm above the average plane of the measurement area. A1 (GPa), the mean modulus of elasticity of the region where the height is less than -5 nm from the mean surface of the measurement area is E A2 When (GPa), the above E A2 to E A1 E divided by A2 / E A1 It is preferable that the value of is 0.1 or greater and less than 1.0, because the water immersion treatment removes the protrusions and allows the base to come into contact with other surfaces, resulting in the development of functions such as adhesion. Here, the region whose height is 5 nm above the average surface of the measurement area refers to the protrusions, and the region whose height is -5 nm below the average surface of the measurement area refers to the base. More preferably, E A2 / E A1 The value of is 0.2 or greater and 0.8 or less, and more preferably E A2 / E A1 The value is between 0.3 and 0.6. A2 / E A1If the value is less than 0.1, the protrusions are too hard compared to the base surface. When using an in-line coating method in which a resin layer is laminated onto the substrate and the laminated layer is stretched simultaneously with the substrate, the difference in stretchability can cause the protrusions to localize. This can result in the base surface coming into contact with other surfaces even before water immersion treatment, causing functions such as adhesion to manifest, and potentially leading to insufficient manifestation of functions such as adhesion after water immersion treatment. In addition, E A2 / E A1 If the value is less than 0.1, the protrusions may easily sink into the soil even before water immersion treatment, and functions such as adhesiveness may be exhibited even before water immersion treatment, which may result in insufficient development of functions such as adhesiveness after water immersion treatment.

[0011] E A2 / E A1 If the value is 1.0 or higher, the resin with adhesive properties may form protrusions, and these protrusions may come into contact with other surfaces even before the water immersion treatment, causing the adhesive properties to manifest. This can result in insufficient manifestation of adhesive properties after the water immersion treatment.

[0012] The polyester film of the present invention was sampled to a size of 1 cm × 1 cm, immersed in 20 g of pure water, ultrasonically treated for 60 minutes at an output of 130 W using an ultrasonic cleaner heated to 23°C, and then allowed to stand and dry at room temperature for 24 hours. In the height image and elastic modulus image of the 30 μm square field of view measured by AFM, the average elastic modulus of the region where the height exceeds 5 nm from the average plane of the measurement area was E B1 (GPa), the mean modulus of elasticity of the region where the height is less than -5 nm from the mean surface of the measurement area is E B2 When (GPa), the above E B1 to E B2 E divided by B1 / E B2A value of 0.1 or greater and less than 1.0 is preferable because the water immersion treatment removes the protrusions, and the base material comes into contact with other surfaces, allowing functions such as adhesion to manifest. The region in which the height exceeds 5 nm from the average surface of the measurement area corresponds to the original base material that has been removed by the water immersion treatment and is now located on the surface side, and the region in which the height is less than -5 nm from the average surface of the measurement area corresponds to the base material portion that appears after the protrusions have been removed by the water immersion treatment. More preferably E B1 / E B2 The value of is 0.2 or greater and 0.8 or less, and more preferably E B1 / E B2 The value is between 0.3 and 0.6. B1 / E B2 If the value is less than 0.1, the new protrusions that appear after the water immersion treatment and have functions such as adhesion to the new surface area are too soft. As a result, when the protrusions come into contact with other surfaces, they collapse, increasing the contact area of ​​the surface area that does not have adhesive or other functions, which may result in insufficient expression of these functions. B1 / E B2 If the value is 1.0 or higher, the new surface area is too soft compared to the new protrusions that appear after water immersion treatment, which have functions such as adhesion. As a result, the protrusions tend to sink into the surface area when in contact with other surfaces, and the contact area of ​​the surface area that does not have functions such as adhesion increases, which may result in insufficient expression of functions such as adhesion. In addition, E B1 / E B2 When the value of is less than 1.0, that is, when the new protrusions are relatively soft and the new base material is relatively hard, the new protrusions that have functions such as adhesion will be crushed first when they come into contact with other surfaces, and the contact area with other surfaces will increase, making it possible to control both the degree to which functions such as adhesion are expressed and the handling properties such as reworkability.

[0013] After careful consideration, we believe the following mechanism is responsible for the emergence of adhesive and other functions after water immersion treatment. Specifically, when the surface A has adhesive and other functions, the protrusions act as a steric obstruction before water immersion treatment, preventing the surface from coming into contact with other surfaces and thus suppressing the emergence of adhesive and other functions. However, when the protrusions are removed by water immersion treatment, the surface becomes a new protrusion, which then comes into contact with other surfaces and allows adhesive and other functions to emerge.

[0014] In addition to adhesiveness, other functions that may emerge after water immersion treatment include conductivity, lubricity, antibacterial properties, and heat sealability. For conductivity, components with antistatic properties can be incorporated into the scalp area; for lubricity, components with high lubricity such as fluorine can be incorporated into the scalp area; for antibacterial properties, fine particles with high antibacterial activity can be incorporated into the scalp area; and for heat sealability, components with high heat fusion properties and low softening temperatures can be incorporated into the scalp area. In this way, when the protrusions are removed by water immersion treatment, the scalp area becomes a new protrusion, thereby exhibiting the desired function.

[0015] E A2 / E A1 and E B1 / E B2 To achieve the above range, it is preferable to form protrusions using an in-line coating method in which a resin layer is laminated onto a substrate and the laminated layer is stretched simultaneously with the substrate. It is also preferable to adjust the stretching conditions after application by in-line coating to the range described later, taking into account the elastic modulus of the resin contained in the coating material applied by in-line coating.

[0016] In the polyester film of the present invention, in the height image of a 30 μm square field of view measured by AFM on surface A, the area ratio of the main component in the region whose height is 5 nm above the average surface of the measurement area to surface A is TA i (%), the area ratio of the component on surface A after water immersion treatment is TA f When expressed as (%), TA f / TA iIt is preferable that it is 0.5 or less. f / TA i It is 0.3 or less, and more preferably TA f / TA i 0.1 or less. TA f / TA i If the value exceeds 0.5, the proportion of protrusions formed by the component in question on surface A increases even after water immersion treatment, which may result in insufficient functional development such as adhesion after water immersion treatment.

[0017] In the polyester film of the present invention, when the distance between protrusions measured on surface A is denoted as D1, a sample of 1 cm × 1 cm is taken, immersed in 20 g of pure water, ultrasonically treated for 60 minutes at an output of 130 W using an ultrasonic cleaner heated to 23°C, and the distance between protrusions measured after standing and drying at room temperature for 24 hours is denoted as D2, it is preferable that the value of D1 / D2 obtained by dividing D1 by D2 is 0.0 or more and 0.8 or less, as this is because functions such as adhesiveness are exhibited by the water immersion treatment. More preferably, it is 0.0 or more and 0.7 or less, and even more preferably 0.0 or more and 0.6 or less. A state in which the value of D1 / D2 is less than 0.0 corresponds to a state in which, for example, many protrusions are removed on surface A by the water immersion treatment, and the distance between the protrusions of the new protrusions that have functions such as adhesiveness after the water immersion treatment becomes too large, so the frictional force increases when in contact with other surfaces, and the handling performance may deteriorate. A D1 / D2 value exceeding 0.8 corresponds, for example, to a state where few protrusions are removed by the water immersion treatment on surface A. In such cases, the surface area, which has functions such as adhesion even before the water immersion treatment, may come into contact with other surfaces and exhibit such functions, resulting in insufficient development of functions such as adhesion through the water immersion treatment.

[0018] In order to set the D1 / D2 value within the above range, it is preferable to apply a blend of at least two or more resins having different elastic moduli to a polyester film laminated on a substrate, and to measure the elastic modulus image in a 30 μm square field of view under AFM conditions of 23°C and 65% RH, such that the elastic modulus of one resin is 1.0 GPa or higher and the elastic modulus of the other resin is less than 1.0 GPa.

[0019] In the polyester film of the present invention, it is preferable that the area ratio RA of the region whose height is 5 nm above the average surface of the measurement area in the height image of the 30 μm square field of view measured by AFM on surface A is 5% or more and 40% or less. More preferably, the area ratio RA is 10% or more and 35% or less, and even more preferably 15% or more and 30% or less. If the area ratio RA is less than 5%, the surface area may come into contact with other surfaces even before water immersion treatment, exhibiting functions such as adhesiveness, and the development of functions such as adhesiveness after water immersion treatment may be insufficient. If the area ratio RA exceeds 40%, the proportion of the surface area on surface A is too low, so the contact area between the surface area and other surfaces becomes small after water immersion treatment, and functions such as adhesiveness may not develop easily.

[0020] In order to set the area ratio RA within the above range, it is preferable to adjust the ratio of the resin that will form the protrusions to the resin that will form the base surface when applying the lamination components to the substrate by the in-line coating method to form the protrusions, to a preferred range.

[0021] The polyester film of the present invention preferably has a maximum peak height Sp of 10 nm or more and 1000 nm or less in a 113 μm square field of view measured with a white light interference microscope on surface A. More preferably, Sp is 15 nm or more and 900 nm or less, and even more preferably, Sp is 20 nm or more and 800 nm or less. If Sp is less than 10 nm, the surface area may come into contact with other surfaces even before water immersion treatment, exhibiting functions such as adhesiveness, and the development of functions such as adhesiveness after water immersion treatment may be insufficient. If Sp exceeds 1000 nm, the volume of the protrusions is too large, and the protrusions cannot be sufficiently removed by water immersion treatment, making it difficult for the surface area with functions such as adhesiveness to come into contact with other surfaces, and thus making it difficult for functions such as adhesiveness to be developed.

[0022] The polyester film of the present invention preferably has a maximum valley depth Sv of 10 nm or more and 1000 nm or less in a 113 μm square field of view measured with a white light interference microscope on surface A. More preferably, Sv is 15 nm or more and 900 nm or less, and even more preferably, Sv is 20 nm or more and 800 nm or less. If Sv is less than 10 nm, the surface area may come into contact with other surfaces even before water immersion treatment, exhibiting functions such as adhesiveness, and the development of functions such as adhesiveness after water immersion treatment may be insufficient. If Sv exceeds 1000 nm, the volume of the valleys in the surface area is too large, making it difficult for the surface area with functions such as adhesiveness to come into contact with other surfaces even after water immersion treatment, and the development of functions such as adhesiveness may be difficult.

[0023] The polyester film of the present invention preferably has an arithmetic mean height Sa of 2 nm or more and 300 nm or less, and a surface texture aspect ratio Str of 0.1 or more and 0.5 or less, measured with a white light interference microscope in a 113 μm square field of view of surface A. More preferably, Sa is 4 nm or more and 200 nm or less, and Str is 0.2 or more and 0.4 or less. If Sa is less than 2 nm, the surface area may come into contact with other surfaces even before water immersion treatment, which may result in insufficient expression of functions such as adhesiveness after water immersion treatment. If Sa exceeds 300 nm, the volume of the protrusions may be too large, making it difficult to remove the protrusions sufficiently during water immersion treatment, and the surface area with functions such as adhesiveness may not come into contact with other surfaces, making it difficult for functions such as adhesiveness to be expressed. Alternatively, if the volume of the valleys in the surface area is too large, the surface area with functions such as adhesiveness may not come into contact with other surfaces even after water immersion treatment, making it difficult for functions such as adhesiveness to be expressed. If Str is less than 0.1, the surface shape has high anisotropy, which may result in uneven direction of function, such as tackiness. If Str exceeds 0.5, the surface shape has high isotropy, which may cause the surface area with tackiness and other functions to come into contact with other surfaces of the same shape even before water immersion treatment, resulting in insufficient development of tackiness and other functions after water immersion treatment. Str is a parameter that represents the isotropy and anisotropy of the surface shape and can be measured in accordance with ISO 25178-2 (2012) using a known roughness meter. Str takes values ​​from 0 to 1, with values ​​closer to 0 indicating high anisotropy and values ​​closer to 1 indicating high isotropy. In order to set the arithmetic mean height Sa and the aspect ratio Str of the surface texture within the above range, it is preferable to apply a blend of at least two or more resins having different elastic moduli when applying the lamination component onto the substrate by an in-line coating method to form protrusions, as measured by AFM under 23°C and 65%RH conditions in an elastic modulus image of a 30 μm square field of view, or to adjust the stretching temperature in the stretching step after coating to a preferred temperature that matches the glass transition temperature of the resin.

[0024] The polyester film of the present invention preferably has ridge-like protrusions on surface A. Ridge-like protrusions are protrusions having flat apex surfaces such that the area of ​​the apex portion of the protrusion is half or more than the area of ​​the base portion of the protrusion. More specifically, they refer to protrusions such that the Ssk when roughness is measured on surface A is 1 or less. Ssk is more preferably 0.7 or less. Ssk is a parameter that represents the degree of bias in the height distribution when centered on the mean surface, and can be measured in accordance with JIS-B0601 (1994) using a known roughness measuring instrument. In order to form ridge-like protrusions, when applying the lamination component to the substrate by the in-line coating method to form the protrusions, it is preferable to blend and apply at least two or more resins having different elastic moduli in the elastic modulus image of a 30 μm square field of view measured by AFM under conditions of 23°C and 65% RH, or to adjust the stretching temperature in the stretching process after coating to a preferred temperature according to the glass transition temperature of the resin.

[0025] In the polyester film of the present invention, it is preferable that the main component of the region whose height exceeds 5 nm from the mean plane of the measurement area in the height image of a 30 μm square field of view measured by AFM on surface A is a water-soluble resin. Here, the main component refers to the component that accounts for 50% or more by mass of the constituent resin components. In the present invention, the statement that the main component of the region whose height exceeds 5 nm from the mean plane of the measurement area in the height image of a 30 μm square field of view measured by AFM on surface A is a water-soluble resin is defined as satisfying the following conditions. A sample of the polyester film of the present invention is taken to a size of 1 cm × 1 cm, a mark is made on the surface opposite to surface A, the bottom of the mark is set as the origin in the XY Cartesian coordinate system, and 10 points are randomly selected in the region whose height exceeds 5 nm from the mean plane in the 30 μm square field of view measured by AFM, and their XY coordinates are recorded. Next, the sample is immersed in water, and the dried sample is fixed flat on the observation stage so that the bottom of the mark becomes the origin in the Cartesian coordinate system. In the 30 μm square field of view measured by AFM, of the 10 points on which the XY coordinates were recorded, two or fewer points have a region that is more than 5 nm above the mean plane.

[0026] In order to make the main component of the region whose height exceeds 5 nm from the average plane of the measurement area a water-soluble resin, when applying the laminated component to the substrate by the in-line coating method, it is preferable to use a water-soluble resin as the blend and apply it, from among at least two or more resins having different elastic moduli as seen in the elastic modulus image of a 30 μm square field of view measured by AFM under conditions of 23°C and 65% RH. Examples of water-soluble resins include polyvinyl alcohol-based resins, polyvinylpyrrolidone-based resins, polyethylene oxide-based resins, polyacrylamide-based resins, and carboxymethylcellulose-based resins. Among these, polyvinylpyrrolidone-based resins and polyacrylamide-based resins, which have high elastic moduli, are particularly preferred.

[0027] In the polyester film of the present invention, it is preferable that the main component of the region whose height is less than -5 nm from the average plane of the measurement area in the height image of a 30 μm square field of view measured by AFM on surface A is an adhesive resin. Here, the main component refers to the component that accounts for 50% or more by mass of the constituent resin components. In the present invention, the statement that the main component of the region whose height is less than -5 nm from the average plane of the measurement area in the height image of a 30 μm square field of view measured by AFM on surface A is an adhesive resin is defined as satisfying the following conditions: In the height image and adhesion strength image of the polyester film of the present invention measured by AFM on surface A, 8 or more points out of 10 randomly selected points from the region whose height is less than -5 nm from the average plane have an adhesion strength SAa of 3 nN or more. The adhesive force referred to here is a numerical representation of the interaction between the cantilever and the sample surface, obtained by analyzing a force curve that captures the relationship between the distance between the cantilever and the sample surface and the force (degree of deflection) acting on the cantilever during a series of actions in which the AFM cantilever approaches and contacts the sample surface, is pressed in, and then separates.

[0028] In order to make the main component of the region whose height is less than -5 nm from the average plane of the measurement area an adhesive resin, when applying the laminated component to the substrate by the in-line coating method, it is preferable to use an adhesive resin and blend it with at least one of several resins having different elastic moduli, as measured by AFM under conditions of 23°C and 65% RH in an elastic modulus image of a 30 μm square field of view. Conventional known resins can be used as the adhesive resin, and specific examples of resins include polyester resins, acrylic resins, urethane resins, and polyvinyl resins (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.). Among these, polyester resins, acrylic resins, and urethane resins are particularly preferred when considering adhesive properties and applicability. The adhesive resin is preferably water-based when considering suitability for in-line coating, and for example, an emulsion-type water-based coating material in which the resin is dispersed in water as an emulsion is preferably used.

[0029] The polyester film of the present invention preferably has an adhesive strength of 0.00 mN / 25 mm or more and 0.02 mN / 25 mm or less, measured at 23°C and 65% RH with a SUS plate with a BA finish on surface A as the adherend. More preferably, it is 0.00 mN / 25 mm or more and 0.01 mN / 25 mm or less, and even more preferably 0.00 mN / 25 mm. If the adhesive strength exceeds 0.02 mN / 25 mm, the adhesive strength is present even before water immersion treatment, which can cause the adhesive surface to easily adhere to conveying materials during transport, potentially worsening handling performance and making it unsuitable for use as an adhesive film.

[0030] The polyester film of the present invention is preferably subjected to ultrasonic treatment for 60 minutes at an output of 130W using an ultrasonic cleaner heated to 23°C, followed by standing drying at room temperature for 24 hours. After placing a BA-finished SUS plate on surface A and pressing it with a 2kg rubber roller for one back-and-forth motion, the adhesive strength measured in an environment of 23°C and 65%RH is preferably 0.01mN / 25mm or more and 0.50mN / 25mm or less. More preferably 0.05mN / 25mm or more and 0.50mN / 25mm or less, and even more preferably 0.10mN / 25mm or more and 0.50mN / 25mm or less. If the adhesive strength is less than 0.01mN / 25mm, it may not be usable as an adhesive film because no adhesive strength is generated even after water immersion treatment.

[0031] The resin film of the present invention, for at least one surface A, has an average elastic modulus of E in the height image and elastic modulus image of a 30 μm square field of view measured by AFM before the removal treatment, where the height of the region is 5 nm above the average plane of the measurement area. C1 (GPa), the mean modulus of elasticity of the region where the height is less than -5 nm from the mean surface of the measurement area is E C2 When (GPa), the above E C2 to E C1 E divided by C2 / E C1 It is preferable that the value of is 0.1 or greater and less than 1.0, because the removal process removes the protrusions, allowing the scalp to come into contact with other surfaces and perform its function. Here, the region whose height is 5 nm above the average surface of the measurement area refers to the protrusions, and the region whose height is -5 nm below the average surface of the measurement area refers to the scalp. More preferably, E C2 / E C1 The value of is 0.2 or greater and 0.8 or less, and more preferably E C2 / E C1 The value is between 0.3 and 0.6. C2 / E C1 If the value is less than 0.1, the protrusions are too hard compared to the scalp, resulting in a significant difference in extensibility and localization of the protrusions. This can cause the scalp to come into contact with other surfaces even before removal treatment, potentially leading to insufficient functional expression after removal treatment. C2 / E C1When the value of

[0032] is 1.0 or more, the component having the function becomes a protrusion, and there may be a case where the protrusion contacts other surfaces or the like even before the removal treatment and the function is expressed, and the function expression property by the removal treatment may be insufficient. D1 For the resin film of the present invention, in the height image and elastic modulus image of a 30 μm square visual field range measured by AFM after the removal treatment, the average elastic modulus E D2 (GPa) of the region where the height exceeds 5 nm from the average plane of the measurement region, and the average elastic modulus E D1 of the region where the height is less than -5 nm from the average plane of the measurement region D2 When divided by E D1 / E D2 is preferably 0.1 or more and less than 1.0 in order to remove the protrusion by the removal treatment and cause the base portion to contact other surfaces or the like and express the function. Here, the region where the height exceeds 5 nm from the average plane of the measurement region corresponds to the original base portion that has become newly located on the surface side by removing the protrusion by the removal treatment, and the region where the height is less than -5 nm from the average plane of the measurement region corresponds to the base material portion that appears by removing the protrusion by the removal treatment. More preferably, the value of E D1 / E D2 is 0.2 or more and 0.8 or less, and still more preferably, the value of E D1 / E D2 is 0.3 or more and 0.6 or less. When the value of E D1 / E D2 is less than 0.1, the new protrusion having a function with respect to the new base portion appearing by the removal treatment is too soft, so when contacting other surfaces or the like, the protrusion collapses and the contact area of the base portion increases, so the function expression may not be sufficient. When the value of E D1 / E D2 is 1.0 or more, the new base portion with respect to the new protrusion having a function appearing by the removal treatment is too soft, so when contacting other surfaces or the like, the protrusion easily sinks into the base portion and the contact area of the base portion having no function increases, so the function expression may be insufficient.

[0033] In this invention, the removal process refers to the process of removing the protrusions on surface A. Known methods can be used for removal, such as cleaning and removing the protrusions using a cleaning agent, physically scraping them off using an abrasive, or removing them using stimulation. One method may be used alone, or two or more methods may be used in combination.

[0034] When cleaning and removing protrusions using a cleaning agent, it is preferable to bring the protrusions on surface A into contact with the cleaning agent. The cleaning agent is not particularly limited, and can be pure water, alkaline electrolyzed water, acidic electrolyzed water, organic solvents, etc., but it is preferable to use pure water because it has a low environmental impact and is easy to handle. Furthermore, the cleaning agent according to the present invention can be formulated with various additives, for example, surfactants, antioxidants, rust inhibitors, pH adjusters, preservatives, viscosity modifiers, defoamers, etc.

[0035] The method for bringing the protrusions of surface A into contact with the cleaning agent is not particularly limited, but examples include immersion, where surface A is immersed in a cleaning tank containing the cleaning agent; application, where a cleaning agent in solution is applied; and spraying, where a cleaning agent in solution or vaporized is sprayed onto surface A. Of these, immersion is preferred from the viewpoint of the penetration of the cleaning agent into the protrusions of surface A.

[0036] In the immersion method, the temperature of the cleaning agent is preferably 23°C or higher. When the temperature of the cleaning agent is 23°C or higher, the viscosity of the cleaning solution is low, making it easier to penetrate the protrusions on surface A, thus easily achieving good cleaning performance. As for the upper limit of the temperature of the cleaning agent in the immersion method, when the cleaning agent is used in solution form, the practical upper limit is a temperature below the boiling point. That is, when using pure water, alkaline electrolyzed water, or acidic electrolyzed water as the cleaning agent, the upper limit is 100°C. In addition, ultrasonic treatment may be performed in the stripping cleaning in the immersion method. The immersion time can be appropriately adjusted depending on the composition of the protrusions on surface A and the cleaning agent, the temperature of the cleaning agent, etc., but usually an immersion time of 10 minutes to 60 minutes is sufficient to remove the protrusions on surface A.

[0037] If the protrusions are to be removed using stimuli, conventionally known stimuli can be used, such as light, heat, and electromagnetism. If light is used as the stimulus, the protrusions can be made to contain components that induce reactions such as melting, evaporation, sublimation, decomposition, isomerization, oxidation, synthesis, and polymerization by light. If heat is used as the stimulus, the protrusions can be made to contain components that induce reactions such as melting, evaporation, sublimation, decomposition, isomerization, oxidation, synthesis, and polymerization by heat. If electromagnetism is used as the stimulus, the protrusions can be made to contain components that induce reactions such as melting, evaporation, sublimation, decomposition, isomerization, oxidation, synthesis, and polymerization by electromagnetism.

[0038] When removing protrusions using stimulation, the components constituting the protrusions include those that undergo reactions such as melting, evaporation, sublimation, decomposition, isomerization, oxidation, synthesis, and polymerization, with components that undergo decomposition reactions being preferred. Examples of components that undergo decomposition reactions include polymers having a polyacetal structure, such as formaldehyde polymers and phthalaldehyde polymers, as well as α-methylstyrene polymers and (meth)acrylate / α-methylstyrene copolymers. Among these, polymers having a polyacetal structure are preferred, and polyacetal polymers obtained from monomers having a ring structure and two aldehyde groups are even more preferred. When selecting a polymer having a polyacetal structure, it is preferable to apply so-called end capping to the ends to prevent depolymerization. The end structure is not particularly limited as long as it can cap the hydroxyl group.

[0039] The molecular weight of the component undergoing the decomposition reaction is selected according to the purpose and application, and is not particularly limited as long as it satisfies the above conditions. However, from the viewpoint of film-forming properties and ease of handling, a weight-average molecular weight in the range of 1,000 to 100,000 is preferred. If the weight-average molecular weight exceeds 100,000, the handling burden may increase as the viscosity increases.

[0040] In addition to adhesiveness, other functions that may emerge after the removal process include conductivity, lubricity, antibacterial properties, and heat-sealability. For conductivity, components with antistatic properties can be incorporated into the scalp area; for lubricity, components with high lubricity such as fluorine can be incorporated into the scalp area; for antibacterial properties, fine particles with high antibacterial activity can be incorporated into the scalp area; and for heat-sealability, components with high heat-sealability and a low softening temperature can be incorporated into the scalp area. In this way, when the protrusions are removed by water immersion treatment, the scalp area becomes a new protrusion, and the function is realized.

[0041] The polyester film of the present invention is preferably a laminated film comprising a base layer mainly composed of polyester resin and a layer mainly composed of a functional resin such as an adhesive resin laminated on one side of the base layer. Here, "main component" refers to a component that accounts for 50% or more by mass of the constituent resin components.

[0042] The polyester referred to in this invention is a material comprising a dicarboxylic acid component and a diol component. The term "component" refers to the smallest unit obtainable by hydrolysis of the polyester. Examples of dicarboxylic acid components constituting such a polyester include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid, or their ester derivatives.

[0043] Furthermore, examples of diol components constituting such polyesters include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, and 1,3-butanediol; alicyclic diols such as cyclohexanedimethanol and spiroglycol; and polysaccharides in which multiple diols are linked together. Among these, from the viewpoint of mechanical properties and transparency, polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and polyesters copolymerized with isophthalic acid or naphthalenedicarboxylic acid in part of the dicarboxylic acid component of PET, and polyesters copolymerized with cyclohexanedimethanol, spiroglycol, and diethylene glycol in part of the diol component of PET are preferably used.

[0044] In this invention, an adhesive resin refers to a resin whose elastic modulus is less than 1.0 GPa in an elastic modulus image of a 30 μm square field of view measured by AFM under conditions of 23°C and 65% RH. Conventional known resins can be used as resins with an elastic modulus of less than 1.0 GPa. Specific examples of resins include polyester resins, acrylic resins, urethane resins, and polyvinyl resins (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.). Among these, polyester resins, acrylic resins, and urethane resins are particularly preferred when considering adhesive properties and applicability.

[0045] When considering suitability for in-line coating, the adhesive resin is preferably water-based. For example, an emulsion-based water-based coating material in which the resin is dispersed in water as an emulsion is preferably used.

[0046] In this invention, it is preferable that the layer mainly composed of a functional resin such as an adhesive resin, laminated on one side of the substrate layer, is a mixture of at least two or more resins having different elastic moduli, because functions such as adhesiveness are exhibited through removal treatments such as water immersion. More specifically, it is preferable that in addition to the main component resin raw material A with an elastic modulus of less than 1.0 GPa, it also contains resin raw material B with an elastic modulus of 1.0 GPa or more, more preferably resin raw material B has an elastic modulus of 2.0 GPa or more, and even more preferably resin raw material B has an elastic modulus of 3.0 GPa or more. It is believed that including such resin raw material B is important because when the layer is inline coated and a film is formed on the substrate, irregularities are formed due to the differences in fluidity and stretchability between resin raw material A and resin raw material B, and these irregularities are important for the exhibiting of functions such as adhesiveness through removal treatments such as water immersion. Conventional known resins can be used as the resin with an elastic modulus of 1.0 GPa or more, but considering suitability for inline coating, it is preferable to use a water-based resin, and it is preferable to use a water-soluble resin. Examples of water-soluble resins include polyvinyl alcohol-based resins, polyvinylpyrrolidone-based resins, polyethylene oxide-based resins, polyacrylamide-based resins, and carboxymethylcellulose-based resins. Among these, polyvinylpyrrolidone-based resins and polyacrylamide-based resins, which have high elastic moduli, are particularly preferred.

[0047] A preferred embodiment of the method for manufacturing the polyester film of the present invention will be described below with specific examples. Here, we will explain using the example of a case in which the base material is a polyester resin and a layer mainly composed of an adhesive resin is laminated on one side thereof.

[0048] The polyester film of the present invention is manufactured using an in-line coating method, in which a water-based coating material is applied to the surface of a polyester film before stretching, and the water in the water-based coating material is evaporated simultaneously with the stretching of the polyester film, thereby forming a resin layer.

[0049] First, the polyester film raw material is fed into a single-screw or twin-screw extruder, heated and melted, and then extruded through a die (T-die) having a straight lip. Preferably, the raw material is dried so that its moisture content is 50 ppm or less. The extruded molten resin is cooled and solidified on a cast drum with a surface temperature of 20°C to 60°C to become an unstretched sheet. At this time, it is preferable to apply static electricity to make the sheet adhere tightly to the cast drum in order to obtain a uniform film.

[0050] Next, the unstretched sheet is heated to a temperature of Tg or higher and Tg+40°C or lower relative to the glass transition temperature Tg of the unstretched sheet using roll heating, and if necessary, infrared heating, and stretched in the longitudinal direction (hereinafter referred to as MD) (MD stretching) to obtain a uniaxially oriented film. MD stretching is preferably performed using the difference in peripheral speed of two or more rolls. Furthermore, stretching in multiple sections while fixing the film with nip rolls to prevent slippage is preferable because it efficiently and uniformly applies stress to the film and makes it easier to impart orientation to the film. The MD stretching ratio is preferably 2.5 times or more and 5.0 times or less. Setting the ratio to 2.5 times or more, more preferably 3.0 times or more, can suppress stretching unevenness in the subsequent TD stretching. Also, setting the ratio to 5.0 times or less, more preferably 4.5 times or less, can prevent the film from breaking during film formation. Next, an aqueous coating material in which the main solvent is water is applied to the obtained uniaxially oriented film by a known coating method such as the bar coating method.

[0051] Next, stretching is performed in a direction perpendicular to the MD (hereinafter referred to as TD) (TD stretching). As a method of TD stretching, it is preferable to use the tenter method, in which both ends in the width direction of the film are gripped with clips and stretched while being transported inside the heat treatment apparatus. At this time, it is preferable that the preheating and stretching temperature for TD stretching be Tg + 10°C or higher and Tg + 50°C or lower relative to the glass transition temperature Tg of the unstretched sheet in order to reduce breakage during stretching. Furthermore, when the applied water-based coating material contains the resin raw material B, it is preferable that the preheating and stretching temperature for TD stretching be 5°C or more lower than the glass transition temperature of resin raw material B, from the viewpoint of enhancing the effect of forming irregularities on the surface by utilizing the difference in the stretchability of the multiple resins contained in the water-based coating material applied to the surface, and it is more preferable that the preheating and stretching temperature for TD stretching be 20°C or more lower than the glass transition temperature of resin raw material B. The TD stretching ratio is preferably 3.0 times or more and 5.5 times or less. By setting the magnification ratio to 3.0 times or more, more preferably 3.5 times or more, the effect of forming surface irregularities by utilizing the difference in the stretchability of multiple resins contained in the water-based coating applied to the surface can be enhanced. Furthermore, by setting the magnification ratio to 5.5 times or less, more preferably 5.0 times or less, it is possible to prevent the polyester film from breaking during film formation. Here, the case of stretching by sequential biaxial stretching, in which stretching in the MD direction and TD direction is performed separately, has been described in detail as an example, but as long as the effects of the present invention are not impaired, simultaneous biaxial stretching, in which stretching in the MD direction and TD direction is performed simultaneously, may also be used. After TD stretching, the polyester film is subsequently heat-treated. The heat treatment is preferably performed for 0.2 to 30 seconds at a temperature of Tm-60°C or higher and Tm-10°C or lower relative to the melting point Tm of the unstretched sheet. Furthermore, in order to relax the tension of the molecular chains of the polyester film and resin layer and improve the uniformity of order, it is preferable to perform a relaxation treatment during the heat treatment process at a relaxation rate of 1.0% to 6.0% in the TD direction for a treatment time of 0.2 to 10 seconds. After that, after uniform slow cooling, the film is cooled to room temperature and wound onto a roll to obtain a polyester film in which a layer mainly composed of adhesive resin is provided on the surface of the polyester film.

[0052] As a preferred embodiment of the polyester film of the present invention, for example, a adherend can be placed so as to contact surface A, and it can be used as a protective film for protecting the adherend. In that case, by subjecting surface A to a removal treatment such as water immersion treatment, it becomes possible to adhere surface A and the adherend, and the separate film required for a normal adhesive film can be eliminated. Furthermore, since adhesiveness is not exhibited until a removal treatment such as water immersion treatment is performed, the reworkability during positioning work becomes good.

[0053] [Evaluation method of properties] A. Water immersion treatment Sample the film into a size of 1 cm × 1 cm, weigh it into 20 g of pure water in a 50 mL beaker, immerse it, and perform ultrasonic treatment at an output of 130 W for 60 minutes using an ultrasonic cleaner with a temperature control of 23°C, and then leave it to stand and dry at room temperature for 24 hours.

[0054] B. Removal treatment using heat as a stimulus Sample the film into a size of 2 cm × 2 cm, fix each side to a metal frame, and perform a reduced-pressure heat treatment at 180°C for 60 minutes in a nitrogen gas environment controlled to a reduced pressure of 20 torr using a vacuum dryer.

[0055] C. AFM measurement (E A1 、E A2 、E B1 、E B2 、E C1 、E C2 、E D1 、E D2 、SAa) The film surface A is fixed to a dedicated sample holder as the measurement surface. Measurement is performed using an AFM (DimensionIcon, manufactured by Burker Corporation) in PeakForceQNM mode. From the obtained force curve, analysis based on the JKR contact theory is performed using the included analysis software (NanoScope Analysis Version 1.40), and height images, elastic modulus images, and adhesion images are obtained. Next, the obtained Height Sensor image of the film surface is subjected to flattening. The reference surface is the surface with a height of 0 nm, determined under the flattening conditions described below. From the height image and elastic modulus image, the average elastic modulus E of the region where the height before water immersion treatment is 5 nm above the average surface of the measurement area is determined within a 30 μm square field of view. A1 (GPa), the mean modulus of elasticity E in the region where the height before water immersion treatment is less than -5 nm from the average surface of the measurement area. A2 (GPa), the average modulus of elasticity E in the region where the height after water immersion treatment is 5 nm above the average surface of the measurement area. B1 (GPa), the mean modulus of elasticity E in the region where the height after water immersion treatment is less than -5 nm from the average surface of the measurement area. B2 (GPa), the average modulus E of the region where the height before removal treatment is 5 nm above the average surface of the measurement area. C1 (GPa), the mean modulus E of the region where the height before removal treatment is less than -5 nm from the average plane of the measurement area. C2 (GPa), the average modulus E of the region where the height after removal treatment is 5 nm above the average surface of the measurement area. D1 (GPa), the mean modulus E of the region where the height after removal treatment is less than -5 nm from the average surface of the measurement area. D2 Calculate (GPa) for each. From the height image and adhesion image, calculate the arithmetic mean SAa(nN) of the adhesion in a 30 μm square field of view.

[0056] Specifically, following the manual of the PeakForce QNM mode, after calibrating the deflection sensitivity, spring constant, and tip curvature of the cantilever, measurements are carried out under the following conditions. Note that the spring constant and tip curvature vary among individual cantilevers. To ensure that they do not affect the measurement, cantilevers that meet the conditions of a spring constant of 0.3 N / m or more and 0.5 N / m or less, and a tip curvature radius of 15 nm or less are adopted and used for the measurement. Measuring device: Atomic Force Microscope (AFM) manufactured by Burker Corporation Measurement mode: PeakForce QNM (Force Curve Method) Cantilever: SCANASYST-AIR manufactured by Burker Corporation (Material: Si, Spring constant K: 0.4 (N / m), Tip curvature radius R: 2 (nm)) Measurement atmosphere: 23°C, 65% RH Measurement range: 30 μm square Resolution: 512×512 Cantilever movement speed: 10 (μm / s) Maximum indentation load (Peak Force Setpoint): 10 (nN) Number of measurements of the measurement sample: The location is changed so that each measurement location is at least 5 μm apart from each other, and 20 measurements are carried out. Measured value: Analyze the 20 measured images, measure each numerical value, and treat the average value as each numerical value possessed by the measurement sample. <Flatten processing> Flatten Order: 3rd [[ID=(27]] Flatten Z Threshholding Direction: No theresholding Find Threshold for: the whole image Flatten Z Threshold %: 0.00 % Mark Excluded Data: Yes.

[0057] D.AFM measurement (RA) Fix the film's surface A to a dedicated sample fixing stage with the measurement surface. Use an AFM (Dimension Icon manufactured by Burker Corporation) to perform measurements under the following conditions. Device: Atomic Force Microscope (AFM) Dimention Icon with ScanAsyst manufactured by Bruker Cantilever: Silicon nitride probe ScanAsyst Air Scanning mode: ScanAsyst Scanning speed: 0.977 Hz Measurement field of view: 30 μm square Sample line: 512 Peak Force SetPoint: 0.0195 V - 0.0205 V Feedback Gain: 10 - 20 LP Deflection BW: 40 kHz ScanAsyst Noise Threshold: 0.5 nm Sample adjustment: Leave standing at 23°C, 65% RH for 24 hours Measurement environment: 23°C, 65% RH Number of measurements of the measurement sample: Change the location so that each measurement location is at least 5 μm apart, and perform 20 measurements. Measured value: Analyze the 20 measured images, measure each numerical value, and treat the average value as each numerical value of the measurement sample. <Calculation of area ratio> Analyze the film surface image obtained under the above conditions using the attached analysis software (NanoScope Analysis Version 1.40). Perform image processing under the same conditions as the Flatten process, and multiply the Mean value of the Area with a height of 5 nm calculated by setting the items in the Detect tab in the Particle Analysis analysis mode as follows by 100 after dividing by the measurement field of view area of the film surface image, and use it as the area ratio (%) of the region with a height of 5 nm or more from the reference surface. <Particle Analysis mode settings> (Detect tab) Threshold Height: -2.00nm Featured Item: Below X Axis:Absolute Number Histogram Bins: 512 Histogram Filter Cutoff:0.00nm Min Peak to Peak: 1.00 nm Left Peak Cutoff: 0.00000% Right Peak Cutoff: 0.00000% (Modify tab) Beughbirhood Size: 3 Number of Pixels Off: 1 No Dilate / Erode operations are performed. (Select tab) Image Cursor Mode:Particle Select Bound Particles: Yes Non-Representative Particles:No Height Reference: Relative To Max Peak Number Histogram Bins: 50.

[0058] E. Surface roughness (Sp, Sv, Sa, Ssk, Str) A 6cm x 6cm film was sampled, and surface A was examined using a scanning white light interference microscope (VertScan). TM Using a 50x objective lens, 30 fields of view measurements were performed with a measurement area of ​​113 μm × 113 μm. The measurement conditions are as follows: <Measurement conditions> Equipment: Hitachi High-Tech Science VS-1540 Objective lens magnification: 50x Wavelength filter: 530 white Measurement device: Piezo Measurement mode: Wave Measurement field size: 113μm × 113μm Measurement environment: 23°C, 65% RH.

[0059] Subsequently, for the obtained microscopic image, image processing is performed under the following conditions using the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope. <Image processing conditions> Interpolation: Complete interpolation Filter: Median 3×3 Surface correction: Fourth order.

[0060] Next, by performing ISO parameter analysis under the following conditions, the maximum peak height Sp, maximum valley depth Sv, arithmetic mean height Sa, skewness Ssk, and aspect ratio Str of the surface texture are obtained in accordance with ISO25178-2 (2012), and the average value of 30 fields of view is taken as the maximum peak height Sp, maximum valley depth Sv, arithmetic mean height Sa, skewness Ssk, and aspect ratio Str of the film of the present invention. <ISO parameter analysis conditions> S-Filter: Automatic Number of divisions: 300 Upper limit of calculation range: 3.000 Lower limit of calculation range: -3.000.

[0061] F. Protrusion interval (D1, D2) Measured in the same manner as in item D above, and for the obtained microscopic image, image processing is performed under the following conditions using the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope. <Image processing conditions> Interpolation: Complete interpolation Filter: Median 3×3 Surface correction: Fourth order.

[0062] Next, a cross-sectional profile in the MD direction is obtained, and the average length Rsm of the elements within 113μm is determined. The average RSm of 30 fields of view before the removal process is taken as the protrusion interval D1, and the average RSm of 30 fields of view after the removal process is taken as the protrusion interval D2.

[0063] G. Identification of water-soluble resins A sample of the polyester film of the present invention is taken to a size of 1 cm x 1 cm, and marks are made on the surface A and the opposite surface. The bottom of the marks is set as the origin in the XY Cartesian coordinate system, and AFM measurement is performed according to item C above. Ten points are randomly selected in the region that is 5 nm above the average surface, and their XY coordinates are recorded. Next, the sample is subjected to the water immersion treatment according to item A above, and the dried sample is fixed flat on the observation stage so that the bottom of the marks is the origin in the Cartesian coordinate system. AFM measurement is performed according to item C above, and if there are two or fewer points among the ten points whose XY coordinates are 5 nm above the average surface, the main component of the region whose height is 5 nm above the average surface of the measurement area is considered to be a water-soluble resin.

[0064] H. Adhesive properties Under conditions of 23°C and 65% RH humidity, a single A4-sized film is rolled into a loop along its length, and the evaluation surfaces at both ends (1 cm from each end) are overlapped. The overlapping 1 cm wide strip is then pressed with a force of 0.1 MPa for 5 seconds, after which the pressure is released, and the adhesive properties are evaluated according to the following criteria. A: Even after the pressure was stopped, the overlapping parts remained stuck together for one hour. B: After the pressure was stopped, the overlapping parts separated within 30 seconds to less than 1 hour. C: Immediately after the pressure was stopped, they were stuck together, but the overlapping parts peeled off in less than 30 seconds. D: The overlapping sections separated immediately after the pressure was stopped.

[0065] I. Adhesion before and after removal treatment The adhesive strength of the film will be measured using Shimadzu Corporation's "EZgraph" in accordance with JIS Z0237 (2009). The measurement conditions are: measurement atmosphere: 23°C, 65%RH, tensile speed: 300 mm / min, peeling method: 180° peeling. The adherend will be a SUS plate with a BA finish on its surface. The adhesive strength will be measured after pressing side A of the film against the adherend once with a 2 kg rubber roller. If adhesion is not achieved and measurement is not possible at the time of pressing, the adhesive strength will be defined as 0.00 mN / 25 mm. [Examples]

[0066] The present invention will be described below with reference to examples, but the present invention is not necessarily limited to these examples.

[0067] [Resin raw material] [PET1] Melt-polymerized PET was obtained by polymerization of terephthalic acid and ethylene glycol using antimony trioxide as a catalyst by a conventional method. The resulting PET (PET1) had a glass transition temperature of 78°C, a melting point of 255°C, an intrinsic viscosity of 0.62, and a terminal carboxyl group content of 20 equivalents / t.

[0068] [PET2] Using a 10% by mass aqueous slurry of PET1 and 0.4 μm cross-linked polystyrene particles (styrene-acrylate copolymer), the mixture was fed into a vented extruder so that the cross-linked polystyrene particles constituted 0.5% by mass relative to the total volume of PET2. The mixture was kneaded while maintaining a reduced pressure of 1 kPa or less to remove moisture, thereby obtaining PET2. The glass transition temperature was 78°C, the melting point was 255°C, the intrinsic viscosity was 0.61, and the amount of terminal carboxyl groups was 22 equivalents / t.

[0069] [Resin raw material A1] As resin raw material A1, a one-component, water-based emulsion type acrylic adhesive resin ("Olivine® BPW 6615", manufactured by Toyo Chem Co., Ltd., solid content concentration 60% by mass) was used.

[0070] [Resin raw material A2] As resin raw material A2, a one-component, water-based emulsion type acrylic adhesive resin ("Olivine® BPW 6441," manufactured by Toyo Chem Co., Ltd., solid content concentration 50% by mass) was used. Resin raw material A2 is an adhesive resin with lower tackiness compared to resin raw material A1.

[0071] [Resin raw material A3] As resin raw material A3, a one-component, water-based emulsion type acrylic adhesive resin ("EXK 23-065", manufactured by Toyo Chem Co., Ltd., solid content concentration 43% by mass) was used. Resin raw material A3 has the same adhesiveness as resin raw material A2 and is an adhesive resin that has been given alkali-degradability to facilitate recycling.

[0072] [Resin raw material B1] As resin raw material B1, a partially saponified polyvinyl alcohol resin ("Gosenol® GL-05", saponification degree 88 mol%, manufactured by Mitsubishi Chemical Corporation, with a glass transition temperature of 80°C, elastic modulus of 2.6 GPa under conditions of 23°C and 65% RH) was prepared as an aqueous solution with a solid content concentration of 10% by mass and used.

[0073] [Resin raw material B2] As resin raw material B2, polyvinylpyrrolidone resin ("K-30", manufactured by Nippon Shokubai Co., Ltd., with a glass transition temperature of 160°C, elastic modulus of 1.7 GPa under conditions of 23°C and 65% RH) was prepared as an aqueous solution with a solid content concentration of 10% by mass and used.

[0074] [Resin raw material B3] In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 26 parts by mass of acrylamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1, molecular weight 71.08), 39 parts by mass of 4-acryloylmorpholine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1, molecular weight 141.17), 36 parts by mass of 2-methoxyethyl acrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1, molecular weight 130.14), and 270 parts by mass of deionized water were charged, and oxygen in the reaction system was removed by passing nitrogen gas through it. Next, the system was heated to 40°C, and under stirring, 0.25 parts by mass of ammonium persulfate and 0.15 parts by mass of sodium bisulfite were added as polymerization initiators. After raising the temperature to 85°C, polymerization was terminated when the viscosity of the reaction solution (calculated at 23°C and 20% solids by mass) reached 150 mPa·s. The mixture was then cooled and further diluted with deionized water to obtain an aqueous polymer solution with a pH of 5.5, a solids content of 20.0% by mass, and a viscosity of 150 mPa·s. This aqueous polymer solution was used as resin raw material B3. The glass transition temperature of the resin was 120°C, and the elastic modulus under conditions of 23°C and 65% RH was 5.3 GPa.

[0075] [Resin raw material B4] In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 5 parts by mass of o-phthalaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 134.13) and 30 parts by mass of dichloromethane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., super-dehydrated, molecular weight 84.93) were charged under a nitrogen atmosphere, and oxygen in the reaction system was removed by passing nitrogen gas through it. Next, the system was brought to -78°C in a dry ice / acetone bath, and 0.35 parts by mass of boron trifluoride diethyl ether complex was added under stirring to start polymerization. After stirring at -78°C for 3 hours, 0.36 parts by mass of phenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 119.12) was added as a encapsulant for the polymerization ends, and stirring continued at -78°C for 1.5 hours. The synthesized polymer was reprecipitation in a large amount of cold methanol (0°C), washed with methanol, and a white solid was recovered. The recovered polymer was prepared as an aqueous dispersion solution with a solid content concentration of 10% by mass and used as resin raw material B4.

[0076] [Surfactant A] As surfactant A, an acetylene alcohol-based surfactant ("EXP.4001," manufactured by Nisshin Chemical Industry Co., Ltd.) was prepared as an aqueous solution with an active ingredient concentration of 2% by mass and used.

[0077] [Coating material A] The following materials were mixed to obtain coating material A. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A1 3.5% by mass Resin raw material B: Resin raw material B1 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 81.3% by mass.

[0078] [Coating material B] Coating material B was obtained by mixing the following materials. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A1 3.5% by mass Resin raw material B: Resin raw material B3 2.6% by mass Surfactant A: 10% by mass Ion-exchanged water: 83.9% by mass.

[0079] [Coating material C] The following materials were mixed to obtain coating material C. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A1 3.5% by mass Resin raw material B: Resin raw material B2 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 81.3% by mass.

[0080] [Coating material D] The following materials were mixed to obtain coating material D. The mass ratio of the solid content of resin raw material A to resin raw material B is 70:30. Resin raw material A: Resin raw material A1 3.0% by mass Resin raw material B: Resin raw material B2 7.8% by mass Surfactant A: 10% by mass Ion-exchanged water: 79.2% by mass.

[0081] [Coating material E] Coating material E was obtained by mixing the following materials. The mass ratio of the solid content of resin raw material A and resin raw material B is 60:40. Resin raw material A: Resin raw material A1 2.6% by mass Resin raw material B: Resin raw material B2 10.4% by mass Surfactant A: 10% by mass Ion-exchanged water: 77.0% by mass.

[0082] [Coating material F] The following materials were mixed to obtain coating material F. The mass ratio of the solid content of resin raw material A to resin raw material B is 85:15. Resin raw material A: Resin raw material A1 3.7% by mass Resin raw material B: Resin raw material B2 3.9% by mass Surfactant A: 10% by mass Ion-exchanged water: 82.4% by mass.

[0083] [Painting material G] The following materials were mixed to obtain coating material G. The mass ratio of the solid content of resin raw material A to resin raw material B is 90:10. Resin raw material A: Resin raw material A1 3.9% by mass Resin raw material B: Resin raw material B2 2.6% by mass Surfactant A: 10% by mass Ion-exchanged water: 83.5% by mass.

[0084] [Coating material H] The following materials were mixed to obtain coating material H. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A2 4.2% by mass Resin raw material B: Resin raw material B2 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 80.6% by mass.

[0085] [Coating material I] The following materials were mixed to obtain coating material I. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A3 4.8% by mass Resin raw material B: Resin raw material B2 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 80.0% by mass.

[0086] [Coating material J] The following materials were mixed to obtain coating material J. Resin raw material A: Resin raw material A1 4.3% by mass Surfactant A: 10% by mass Ion-exchanged water: 85.7% by mass.

[0087] [Coating material K] The following materials were mixed to obtain coating material K. The mass ratio of solid content between resin raw material A and resin raw material B is 80:20. Resin raw material A: Resin raw material A1 3.5% by mass Resin raw material B: Resin raw material B4 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 81.3% by mass.

[0088] [Painting material L] The following materials were mixed to obtain coating material L. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A2 4.2% by mass Resin raw material B: Resin raw material B4 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 80.6% by mass.

[0089] [Coating material M] The following materials were mixed to obtain coating material M. The mass ratio of the solid content of resin raw material A to resin raw material B is 80:20. Resin raw material A: Resin raw material A3 4.8% by mass Resin raw material B: Resin raw material B4 5.2% by mass Surfactant A: 10% by mass Ion-exchanged water: 80.0% by mass.

[0090] [Coating material N] The following materials were mixed to obtain coating material N. The mass ratio of the solid content of resin raw material A to resin raw material B is 70:30. Resin raw material A: Resin raw material A1 3.0% by mass Resin raw material B: Resin raw material B4 7.8% by mass Surfactant A: 10% by mass Ion-exchanged water: 79.2% by mass.

[0091] [Coating material O] The following materials were mixed to obtain coating material O. The mass ratio of the solid content of resin raw material A to resin raw material B is 60:40. Resin raw material A: Resin raw material A1 2.6% by mass Resin raw material B: Resin raw material B4 10.4% by mass Surfactant A: 10% by mass Ion-exchanged water: 77.0% by mass.

[0092] [Painting material P] The following materials were mixed to obtain coating material P. The mass ratio of the solid content of resin raw material A to resin raw material B is 85:15. Resin raw material A: Resin raw material A1 3.7% by mass Resin raw material B: Resin raw material B4 3.9% by mass Surfactant A: 10% by mass Ion-exchanged water: 82.4% by mass.

[0093] [Coating Material Q] The following materials were mixed to obtain coating material Q. The mass ratio of the solid content of resin raw material A to resin raw material B is 90:10. Resin raw material A: Resin raw material A1 3.9% by mass Resin raw material B: Resin raw material B4 2.6% by mass Surfactant A: 10% by mass Ion-exchanged water: 83.5% by mass.

[0094] (Example 1) PET1 was vacuum-dried at 160°C for 3 hours, then placed in an extruder, melted at 280°C, and extruded through a die onto a casting drum with a surface temperature of 23°C to produce an unstretched sheet. Subsequently, the sheet was preheated with a group of heated rolls, then stretched 3.5 times in the longitudinal direction (MD direction) at 90°C, and finally cooled with a group of rolls at 23°C to obtain a uniaxially oriented film.

[0095] The obtained uniaxially oriented film was coated with coating material A to a thickness of approximately 10 μm. Next, both ends of the coated uniaxially oriented film in the width direction were grasped with clips and guided to the preheating zone. The ambient temperature of the preheating zone was set to 95°C. Subsequently, the film was continuously stretched 3.8 times in the width direction (TD direction) perpendicular to the longitudinal direction in the stretching zone at 105°C, and then heat-treated for 10 seconds in the heat treatment zone at 230°C to obtain a polyester film. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. The development of tackiness after water immersion treatment was good.

[0096] (Examples 2-9) A polyester film was obtained in the same manner as in Example 1, except that the coating material to be applied was changed to the coating material listed in the table. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. Example 3 showed better adhesion development after water immersion treatment than Example 1, while Examples 2, 5, and 7 showed slightly worse adhesion development after water immersion treatment than Example 1. Otherwise, they were equivalent to Example 1.

[0097] (Example 10) A polyester film was obtained in the same manner as in Example 1, except that the stretching ratio for TD stretching was changed to the ratio shown in the table. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. The obtained polyester film showed slightly inferior adhesion after water immersion treatment compared to Example 1.

[0098] (Comparative Example 1) In Example 1, a uniaxially oriented film was stretched in the width direction without applying a coating to obtain a biaxially oriented film. Next, coating A was applied to the obtained biaxially oriented film to a thickness of approximately 10 μm, and dried at 150°C for 60 seconds to obtain a polyester film with coating A applied offline. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. The obtained polyester film showed poor adhesion after water immersion treatment.

[0099] (Comparative Example 2) PET2 was vacuum-dried at 160°C for 3 hours, then placed in an extruder, melted at 280°C, and extruded through a die onto a casting drum with a surface temperature of 23°C to produce an unstretched sheet. Subsequently, the sheet was preheated with a group of heated rolls, then stretched 3.5 times in the longitudinal direction (MD direction) at 90°C, and finally cooled with a group of rolls at 23°C to obtain a uniaxially oriented film.

[0100] The obtained uniaxially oriented film was then guided to the preheating zone by clipping both ends in the width direction of the film. The ambient temperature of the preheating zone was set to 95°C. Subsequently, the film was continuously stretched 3.8 times in the width direction (TD direction) perpendicular to the longitudinal direction in a stretching zone at 105°C, and then heat-treated for 10 seconds in a heat treatment zone at 230°C to obtain a polyester film. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. The obtained polyester film showed poor adhesion after water immersion treatment.

[0101] (Comparative Example 3) A film was obtained in the same manner as in Example 1, except that the coating material to be applied was changed to coating material J. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. The obtained polyester film showed poor adhesion after water immersion treatment.

[0102] (Comparative Example 4) In Example 1, a uniaxially oriented film was stretched in the width direction without applying a coating material to obtain a biaxially oriented film. Next, coating material J was applied to the obtained biaxially oriented film to a thickness of approximately 10 μm, dried at 150°C for 30 seconds, then a hairline-finished metal plate with a surface roughness Ra of 1 μm was pressed onto the coated surface at a surface pressure of 0.2 MPa, and the film was dried again at 150°C for 60 seconds. After that, the metal plate was peeled off to obtain a polyester film. The properties of the obtained polyester film and the properties of the polyester film after water immersion treatment are shown in the table. The obtained polyester film showed poor adhesion after water immersion treatment. Note that in Examples 1 to 10, TA f / TA i The value was 0.5 or less.

[0103] [Table 1-1]

[0104] [Table 1-2]

[0105] (Example 11) PET1 was vacuum-dried at 160°C for 3 hours, then placed in an extruder, melted at 280°C, and extruded through a die onto a casting drum with a surface temperature of 23°C to produce an unstretched sheet. Subsequently, the sheet was preheated with a group of heated rolls, then stretched 3.5 times in the longitudinal direction (MD direction) at 90°C, and finally cooled with a group of rolls at 23°C to obtain a uniaxially oriented film.

[0106] The obtained uniaxially oriented film was coated with coating material K to a thickness of approximately 10 μm. Next, both ends of the coated uniaxially oriented film in the width direction were grasped with clips and guided to the preheating zone. The ambient temperature of the preheating zone was set to 95°C. Subsequently, the film was continuously stretched 3.8 times in the width direction (TD direction) perpendicular to the longitudinal direction in the stretching zone at 105°C, and then heat-treated for 10 seconds in the heat treatment zone at 230°C to obtain a polyester film. The properties of the obtained polyester film and the properties of the polyester film after removal treatment using heat as a stimulus are shown in the table. The development of tackiness by removal treatment using heat as a stimulus was good.

[0107] (Examples 12-17) A polyester film was obtained in the same manner as in Example 11, except that the coating material to be applied was changed to the coating material listed in the table. The properties of the obtained polyester film and the properties of the polyester film after removal treatment using heat as a stimulus are shown in the table. Example 16 showed better adhesion development after removal treatment using heat as a stimulus than Example 11, while Examples 12, 13, and 15 showed slightly worse adhesion development after removal treatment using heat as a stimulus than Example 11. Otherwise, it was equivalent to Example 11.

[0108] [Table 2] [Industrial applicability]

[0109] The film of the present invention is a film whose surface properties, such as tackiness, change upon removal treatment, such as water immersion, and can be used, for example, as an adhesive film for surface protection. Since tackiness does not develop until removal treatment such as water immersion is performed, a separator film required for ordinary adhesive films is unnecessary, and reworkability during positioning work is also improved. [Explanation of symbols]

[0110] 1. Polyester film 2. Protrusions present on surface A before water immersion treatment 3. Surface area of ​​surface A before water immersion treatment 4. Protrusions present on surface A after water immersion treatment 5. Bare surface area present on surface A after water immersion treatment 6. Resin film 7. Protrusions present on surface A before removal process 8. Bare surface area present on surface A before removal treatment 9. Protrusions present on surface A after removal process 10. Bare surface area present on surface A after removal treatment

Claims

1. A polyester film that satisfies the following conditions in the height image and elastic modulus image of a 30 μm square field of view measured by AFM before and after water immersion treatment on at least one surface A. 0.1 ≦ E Ａ２ / E Ａ１ < 1.0 0.1 ≦ E Ｂ１ / E Ｂ２ < 1.0 E Ａ１ : The average modulus of elasticity (GPA) of the region where the height before water immersion treatment is 5 nm above the average surface of the measurement area. E Ａ２ : The average modulus of elasticity (GPa) of the region where the height before water immersion treatment is less than -5 nm from the average surface of the measurement area. E Ｂ１ : The average modulus of elasticity (GPA) of the region where the height after water immersion treatment exceeds 5 nm from the average surface of the measurement area. E Ｂ２ : The average modulus of elasticity (GPA) of the region where the height after water immersion treatment is less than -5 nm from the average surface of the measurement area. <Water immersion treatment conditions> The film is sampled to a size of 1 cm x 1 cm, immersed in 20 g of pure water, and ultrasonically treated for 60 minutes at an output of 130 W using an ultrasonic cleaner heated to 23°C. After that, it is allowed to dry at room temperature for 24 hours.

2. For at least one surface A, the protrusion interval D before the water immersion treatment １ and the protrusion interval D after the water immersion treatment ２ is a polyester film that satisfies the following conditions. 0.0≦D １ / D ２ ≦0.8 <Water immersion treatment conditions> The film is sampled to a size of 1 cm x 1 cm, immersed in 20 g of pure water, and ultrasonically treated for 60 minutes at an output of 130 W using an ultrasonic cleaner heated to 23°C. After that, it is allowed to dry at room temperature for 24 hours.

3. The polyester film according to claim 1 or 2, wherein, in the height image of a 30 μm square field of view measured with AFM on surface A, the area ratio RA of the region whose height is 5 nm above the average surface of the measurement area is 5% or more and 40% or less.

4. The polyester film according to claim 1 or 2, wherein, in a 113 μm square field of view measured with a white light interference microscope for surface A, the maximum peak height Sp is 10 nm or more and 1000 nm or less.

5. The polyester film according to claim 1 or 2, wherein, in a 113 μm square field of view measured with a white light interference microscope on surface A, the maximum valley depth Sv is 10 nm or more and 1000 nm or less.

6. The polyester film according to claim 1 or 2, wherein, in a 113 μm square field of view measured with a white light interference microscope on surface A, the arithmetic mean height Sa is 2 nm or more and 300 nm or less, and the aspect ratio Str of the surface properties is 0.1 or more and 0.5 or less.

7. For surface A, the spacing of the protrusions D before water immersion treatment. １ and the gap between the protrusions D after water immersion treatment ２ The polyester film according to claim 1, wherein the following conditions are met. 0.0≦D １ / D ２ ≦0.8 <Water immersion treatment conditions> The film is sampled to a size of 1 cm x 1 cm, immersed in 20 g of pure water, and ultrasonically treated for 60 minutes at an output of 130 W using an ultrasonic cleaner heated to 23°C. After that, it is allowed to dry at room temperature for 24 hours.

8. The polyester film according to claim 1 or 2, wherein, in the height image of a 30 μm square field of view measured with AFM on surface A, the main component of the region whose height is 5 nm above the average surface of the measurement area is a water-soluble resin.

9. The polyester film according to claim 1 or 2, wherein, in the height image of a 30 μm square field of view measured with AFM on surface A, the main component of the region where the height is less than -5 nm from the average surface of the measurement area is an adhesive resin.

10. The polyester film according to claim 9, used for the purpose of protecting an object to be placed so as to be in contact with surface A.

11. The polyester film according to claim 10, which is used by placing an object to be adhered to on surface A and then immersing it in water to make surface A and the object adhere to each other.

12. A resin film that satisfies the following conditions in the height image and elastic modulus image of a 30 μm square field of view measured by AFM before and after the removal treatment on at least one surface A. 0.1 ≦ E Ｃ２ / E Ｃ１ < 1.0 0.1 ≦ E Ｄ１ / E Ｄ２ < 1.0 E Ｃ１ : The average modulus of elasticity (GPA) of the region where the height before removal treatment is 5 nm above the average surface of the measurement area. E Ｃ２ : The average modulus of elasticity (GPA) of the region where the height before removal treatment is less than -5 nm from the average plane of the measurement area. E Ｄ１ : The average modulus of elasticity (GPA) of the region where the height after removal treatment exceeds 5 nm from the average surface of the measurement area. E Ｄ２ : The average modulus of elasticity (GPA) of the region where the height after removal treatment is less than -5 nm from the average plane of the measurement area.

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