Layered polyethylene terephthalate film, mold release film, and method for producing layered polyethylene terephthalate film

Abstract

The present invention provides a layered polyethylene terephthalate film which is capable of suppressing transfer of a surface shape to a processed product, a method for producing the same, and a mold release film. Provided is a layered polyethylene terephthalate film comprising a support layer that is formed of a polyethylene terephthalate film and a covering layer that has a surface on which to laminate a functional layer. The support layer contains at least one element from among the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. The total amount of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 0.1-600 ppm with respect to the total mass of the layered polyethylene terephthalate film. The covering layer contains a polyester resin. The three-dimensional center plane average surface roughness (SRa) of said surface is 5-30 nm. Alternatively, the maximum peak height (SRp) of said surface is not more than 1,000 nm.

Description

Laminated polyethylene terephthalate film, release film, and method for producing laminated polyethylene terephthalate film

[0001] The present invention relates to a laminated polyethylene terephthalate film, a release film, and a method for producing a laminated polyethylene terephthalate film.

[0002] Films (hereinafter sometimes referred to as process films) that include functional layers having various functions on the surface of a base film such as a synthetic resin are used in fields such as electronic components, optical components, labels, mold release materials, etc. Among the above films, used films, films that do not meet specifications, films that have been damaged during distribution, etc. are usually discarded (hereinafter such films may be referred to as films to be discarded).

[0003] Patent Document 1 discloses a method for measuring the amount of impurities in used films, a method for recycling used films, and a method for converting the recycled raw materials into films. For example, Patent Document 1 discloses removing a silicone-containing release layer formed on the surface of a substrate film, barium titanate, and an adhesive as residues.

[0004] Japanese Patent Application Laid-Open No. 2021-115862

[0005] For the effective use of resources, it is preferable to recycle films that are scheduled to be discarded. In particular, the distribution amount of films having a functional layer and a base film (i.e., films with functional layers), for example, release films, has been increasing in recent years, and the amount of waste has also been increasing, so there is a demand for the establishment of a circular recycling system for release films. In other words, there is a demand for release films that are scheduled to be discarded to be utilized in the production of release films.

[0006] In addition, recycling yield is an important factor in establishing a circular recycling system.

[0007] The technology of Patent Document 1 has a recycling yield that varies depending on the amount of impurities contained in the film, and the recycling yield tends to deteriorate as the amount of impurities increases. For example, the technology of Patent Document 1 applies thermal recycling when the amount of impurities in the film is 0.2% by weight or more when the total weight of the film is 100% by weight, and in this case the recycling yield is 0.

[0008] Furthermore, release films are always required to have low surface roughness from the viewpoint of surface transfer onto processed products, and the same applies to recycled films. The processed products are, for example, resin sheets such as ceramic green sheets, multilayer ceramic capacitors made of ceramic green sheets, semiconductor components, or optical films. However, while the technology of Patent Document 1 describes the amount of impurities, it does not describe the film surface roughness, resulting in a problem of not achieving the desired surface roughness.

[0009] Therefore, an object of the present invention is to provide a laminated polyethylene terephthalate film that can suppress the transfer of surface topography to processed products, a method for producing the same, and a release film. A preferred embodiment of the present invention relates to a laminated polyethylene terephthalate film that has an excellent recycling yield and can suppress the transfer of surface topography to processed products, even when using recycled resin recovered from films to be discarded, particularly films with functional layers, such as release films. The recycled resin contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0010] As a result of intensive research to solve the above-mentioned problems, the inventors have succeeded in controlling the surface roughness within a predetermined range in a recycled film containing impurities consisting of one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and have found that the above-mentioned problems can be solved, thereby completing the present invention.

[0011] More specifically, in recent years, there has been an increasing need for environmental impact reduction activities, including the SDGs and carbon neutrality. The present inventors have conducted extensive research into improving the recycling yield of process films, such as release films, and have found that, among various factors, improving the recycling yield of process films requires controlling the recycling process of the process film. However, simply improving the recycling yield may result in insufficient properties required of the process film. Therefore, when a laminated polyethylene terephthalate film is used as a base film for a process film, such as a release film, it is necessary to achieve a good balance between improving the releasability of the processed product and suppressing the transfer of the surface shape of the process film to the processed product. There is also a demand for recycling films containing particles. In light of this situation, the present inventors have developed a laminated polyethylene terephthalate film, a manufacturing method thereof, and a release film that can suppress the transfer of the surface shape of the processed product, even when using a recycled resin containing one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0012] The present invention provides the following aspects: [Item 1] A laminated polyethylene terephthalate film comprising a support layer made of a polyethylene terephthalate film and a coating layer having a surface for laminating a functional layer, wherein the support layer contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and the total amount of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 0.1 ppm or more and 600 ppm or less relative to the total mass of the laminated polyethylene terephthalate film, and the coating layer is a layer containing a polyester resin, and the laminated polyethylene terephthalate film satisfies at least one of the following requirements (1) and (2): (1) The three-dimensional center plane average surface roughness (SRa) of the surface is 5 nm or more and 30 nm or less, or (2) The maximum peak height (SRp) of the surface is 1,000 nm or less. [Item 2] A laminated polyethylene terephthalate film comprising a support layer made of a polyethylene terephthalate film and a coating layer having a surface for laminating a functional layer, wherein the support layer contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and the total amount of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 0.1 ppm or more and 600 ppm or less based on the total mass of the support layer, and the coating layer is a layer containing a polyester resin, and the laminated polyethylene terephthalate film satisfies at least one of the following requirements (1) and (2): (1) The three-dimensional center plane average surface roughness (SRa) of the surface is 5 nm or more and 30 nm or less, and (2) The maximum peak height (SRp) of the surface is 1,000 nm or less. [Item 3] The laminated polyethylene terephthalate film according to Item 1 or 2, wherein the thickness of the coating layer is 0.5 μm or more and 8.5 μm or less. [Item 4] The melt resistivity at 275° C. (ρi(10 8The laminated polyethylene terephthalate film according to any one of Items 1 to 3, having a resistivity (Ω·cm) of 1.00 or less. [Item 5] The support layer contains one or more of Ti, Ni, Cu, Pt, Pd, Ag, and Au, and the total amount of Ti, Ni, Cu, Pt, Pd, Ag, and Au is 10 ppm or more relative to the total mass of the support layer or the laminated polyethylene terephthalate film. [Item 6] The laminated polyethylene terephthalate film according to any one of Items 1 to 5, having a Si content of 300 ppm or less relative to the total mass of the support layer or the laminated polyethylene terephthalate film. [Item 7] The laminated polyethylene terephthalate film according to any one of Items 1 to 6, having a Ba content of 300 ppm or less relative to the total mass of the support layer or the laminated polyethylene terephthalate film. [Item 8] The laminated polyethylene terephthalate film according to any one of Items 1 to 7, wherein the support layer contains 5% by mass or more and 100% by mass or less of a resin obtained by material recycling and / or chemical recycling of a film with a functional layer. [Item 9] The laminated polyethylene terephthalate film according to any one of Items 1 to 8, wherein at least one of the support layer and the coating layer contains lubricant particles, and the content of the lubricant particles is 500 ppm or more and 5,000 ppm or less with respect to the total mass of the laminated polyethylene terephthalate film. [Item 10] The laminated polyethylene terephthalate film according to any one of Items 1 to 9, wherein the support layer has an intrinsic viscosity (IV) of 0.400 dL / g or more and 0.700 dL / g or less. [Item 11] A release film comprising: the laminated polyethylene terephthalate film according to any one of Items 1 to 10; and the functional layer provided on the surface of the coating layer provided on the laminated polyethylene terephthalate film, wherein the functional layer is a release layer.[Item 12] A method for producing the laminated polyethylene terephthalate film according to any one of Items 1 to 11, comprising the following steps: a pulverization step comprising pulverizing a polyethylene terephthalate film having a functional layer to form a pulverized product, a chipping step comprising chipping the pulverized product to form recycled chips, and a recycled film formation step comprising melt-extruding a molding material for forming the support layer, the molding material including the recycled chips and polyethylene terephthalate chips different from the recycled chips.

[0013] The following aspects of the present invention are also preferred: [Item 13] A laminated polyethylene terephthalate film comprising a support layer made of a polyethylene terephthalate film and a coating layer having a surface onto which a functional layer is to be laminated, wherein the support layer contains one or more of Si, Ti, and Ba, and the total amount of Si, Ti, and Ba is 0.1 ppm or more and 500 ppm or less relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film, the coating layer is a layer containing a polyester resin, and the three-dimensional center plane average surface roughness (SRa) of the surface is 5 nm or more and 30 nm or less, and the maximum peak height (SRp) of the surface is 1000 nm or less. [Item 14] The laminated polyethylene terephthalate film, release film, or method for producing a laminated polyethylene terephthalate film according to any of the above items, wherein the support layer contains one or more of Si, Ti, and Ba, and the total amount of Si, Ti, and Ba is 0.1 ppm or more and 500 ppm or less relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. [Item 15] The laminated polyethylene terephthalate film, release film, or method for producing a laminated polyethylene terephthalate film according to any of the above items, wherein the laminated polyethylene terephthalate film further comprises a second coating layer, the support layer is sandwiched between the coating layer and the second coating layer, and the second coating layer is a layer containing a polyester resin. [Item 16] The method for producing a laminated polyethylene terephthalate film, release film, or laminated polyethylene terephthalate film according to any of the above items, wherein the support layer contains Si. [Item 17] The laminated polyethylene terephthalate film, the release film, or the method for producing a laminated polyethylene terephthalate film according to any one of the above items, wherein the support layer contains Ti or Ba.[Item 18] The laminated polyethylene terephthalate film, release film, or method for producing a laminated polyethylene terephthalate film according to any of the above items, wherein the support layer contains one or more of Ni, Cu, Pt, Pd, Ag, and Au, i.e., contains at least one element selected from the group consisting of Ni, Cu, Pt, Pd, Ag, and Au. [Item 19] The laminated polyethylene terephthalate film, release film, or method for producing a laminated polyethylene terephthalate film according to any of the above items, wherein the surface (i.e., the first surface) has a three-dimensional center plane average surface roughness (SRa) of 7 nm or more or 8 nm or more. [Item 20] The laminated polyethylene terephthalate film, release film, or method for producing a laminated polyethylene terephthalate film according to any of the above items, wherein the first surface has a maximum peak height (SRp) of more than 200 nm or 210 nm or more. [Item 21] The laminated polyethylene terephthalate film, release film, or method for producing a laminated polyethylene terephthalate film according to any one of the above items, wherein the average particle size of the lubricant particles is 2.0 μm or less or 1.0 μm or less.

[0014] The present invention provides a laminated polyethylene terephthalate film capable of suppressing the transfer of a surface shape to a processed product, a method for producing the same, and a release film. The present invention provides a laminated polyethylene terephthalate film capable of suppressing the transfer of a surface shape to a processed product, even when using a recycled resin containing one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0015] The present invention will be described in detail below. A laminated polyethylene terephthalate film according to an embodiment of the present invention (hereinafter sometimes simply referred to as the "laminated polyethylene terephthalate film of the present invention") comprises a support layer made of a polyethylene terephthalate film and a coating layer having a surface on which a functional layer is laminated. The support layer contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. The total amount of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 0.1 ppm or more and 600 ppm or less relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. Preferably, the coating layer is a layer containing a polyester resin. The laminated polyethylene terephthalate film satisfies at least one of the following requirements (1) and (2). Preferably, the laminated polyethylene terephthalate film satisfies both of the following requirements (1) and (2). (1) The three-dimensional center plane average surface roughness (SRa) of the surface is 5 nm or more and 30 nm or less, and (2) the maximum peak height (SRp) of the surface is 1000 nm or less.

[0016] The support layer, i.e., polyethylene terephthalate film, contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and therefore can be produced using recycled resin. Therefore, the present invention can contribute to reducing environmental impact. This is explained below. When a polyethylene terephthalate film is produced using a resin recycled from a silicone-based release film, i.e., a film with a silicone-based release layer, the polyethylene terephthalate film may contain Si derived from the silicone-containing release layer. Furthermore, when a polyethylene terephthalate film is produced using a resin recycled from a release film used in the manufacture of a multilayer ceramic capacitor, the polyethylene terephthalate film may contain Ti and Ba derived from barium titanate remaining in the release film. Similarly, when a polyethylene terephthalate film is produced using a resin recycled from a release film used in the manufacture of a multilayer ceramic capacitor, the polyethylene terephthalate film may contain electrode components of the multilayer ceramic capacitor remaining in the release film. This is thought to be because, during the production of a multilayer ceramic capacitor, electrodes are printed on a ceramic green sheet formed on a release film and then wound up, causing electrode components to adhere to the release film during this winding process. The electrode components include one or more of Ni, Cu, Pt, Pd, Ag, and Au. When a support layer, i.e., a polyethylene terephthalate film, is produced using recycled resin, the polyethylene terephthalate film may contain one or more of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. While the support layer (i.e., polyethylene terephthalate film) of the laminated polyethylene terephthalate film of the present invention is preferably produced using recycled resin, it may also be produced without using recycled resin.Furthermore, since the upper limit for the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 600 ppm, recycled resins that can be used to produce polyethylene terephthalate films may contain certain amounts of these elements. In other words, recycled resins that can be used to produce polyethylene terephthalate films are permitted to contain certain amounts of these elements. This improves the recycling yield (see Patent Document 1), specifically, the recycling yield of recycled resins that can be used to produce polyethylene terephthalate films. Furthermore, since the three-dimensional center plane average surface roughness (SRa) of the coating layer surface is 30 nm or less, or the maximum peak height (SRp) is 1000 nm or less, excessive unevenness can be avoided on the surface of processed products (hereinafter sometimes referred to as "molded products") produced using the laminated polyethylene terephthalate film. For example, when producing ceramic green sheets using a release film containing a laminated polyethylene terephthalate film and a release layer, excessive unevenness can be avoided on the surface of the ceramic green sheet. In other words, the transfer of the surface shape to the ceramic green sheet can be suppressed.

[0017] In one aspect, the support layer of the laminated polyethylene terephthalate film of the present invention can contain 5% by mass or more and 100% by mass or less of a resin obtained by material recycling and / or chemically recycling a film with a functional layer. Here, the "film with a functional layer" includes a substrate film and a functional layer. When the functional layer is a release layer, the film with a functional layer may be referred to as a "release film." In this specification, material recycling and / or chemical recycling may also be simply referred to as recycling.

[0018] The following mainly describes a configuration in which the laminated polyethylene terephthalate film is used for release purposes (typically as a base film for a release film), but the laminated polyethylene terephthalate film is not limited to release purposes. The following mainly describes a configuration in which the laminated polyethylene terephthalate film is a biaxially stretched laminated polyethylene terephthalate film, i.e., a biaxially oriented laminated polyethylene terephthalate film, but the laminated polyethylene terephthalate film is not limited to a biaxially oriented laminated polyethylene terephthalate film. The following may also describe a configuration in which the laminated polyethylene terephthalate film includes a first coating layer, a second coating layer, and a support layer sandwiched between the first and second coating layers. The first coating layer may have a surface on which a functional layer is laminated, or the second coating layer may have a surface on which a functional layer is laminated. The laminated polyethylene terephthalate film is not limited to this configuration. The laminated polyethylene terephthalate film may not include a second coating layer. In this case, the first coating layer may have a surface on which a functional layer is laminated. The description of the coating layer described below can be treated as a description of the first coating layer and the second coating layer. Hereinafter, the element contents (e.g., the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, or the content of each element) will be mainly described based on the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. Of these, the total mass of the laminated polyethylene terephthalate film is preferred. The element contents may be within the preferred ranges described below, both based on the total mass of the support layer and the total mass of the laminated polyethylene terephthalate film.

[0019] In one embodiment, the laminated polyethylene terephthalate film of the present invention contains a resin recycled from a film with a functional layer. The film with a functional layer may be a used film with a functional layer. The film with a functional layer may be a release film, for example, a used release film. A used release film refers to a release film obtained after, for example, forming and laminating an object to be released on a release layer and then peeling the object from the release layer. In addition, used release films may include release films that have not been used and stored for a long time after production, release films that have not been used because they do not satisfy the required properties, and release films that do not achieve their original purpose, such as cut edges.

[0020] In one embodiment, the recycled functional layer-equipped film, i.e., the functional layer-equipped film used as a raw material for recycled resin, is a release film used to mold a resin sheet containing an inorganic compound. Examples of inorganic compounds include metal particles, metal oxides, and minerals, such as calcium carbonate, silica particles, aluminum particles, and barium titanate particles. Examples of resins contained in the resin sheet include polyvinyl acetal resin and poly(meth)acrylic acid ester resin. For example, the functional layer-equipped film is used in the manufacture of resin sheets that require high smoothness, such as semiconductor components, ceramic green sheets, and optical films. By recycling films used for such applications, various physical properties, such as surface roughness, can be more effectively achieved. Furthermore, functional layer-equipped films (e.g., release films) used for such applications preferably contain particles to maintain smoothness and exhibit windability. For example, the functional layer can contain resins such as silicone-based, cyclic olefin-based, acyclic olefin-based, fluorine-based, alkyd-based, acrylic, melamine-based, and epoxy-based resins, as described below.

[0021] The film with a functional layer to be recycled is a film in which a functional layer is provided on at least one surface of a base film containing a thermoplastic resin. The base film is preferably a polyester film, and may be, for example, the laminated polyethylene terephthalate film of the present invention. This allows the laminated polyethylene terephthalate film or release film of the present invention to be recycled and reused multiple times, making it suitable for the efficient use of resources required in a recycling-oriented society.

[0022] The present invention can also reuse components other than polyester components as long as they do not deviate from the scope of the present invention. Materials, etc., are not particularly limited as long as they fall within the scope of the present invention. Particularly preferably, resins recycled from functional layer-attached films in which a functional layer is directly laminated on a substrate film can be used. The content of this resin, i.e., recycled resin, is, for example, 5% by mass or more and 100% by mass or less, when the total mass of the polyethylene terephthalate film (i.e., support layer) is taken as 100% by mass. By using a functional layer-attached film in which a functional layer is directly laminated on a substrate film, a functional layer-attached film with fewer impurities can be recycled, thereby further reducing the surface roughness of the laminated polyethylene terephthalate film and reducing haze. Examples of polyethylene terephthalate include homopolyethylene terephthalate and copolymer polyethylene terephthalate. Materials for the polyester resin contained in the coating layer include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycyclohexanedimethanol-terephthalate, and the like, without any particular limitations. Of these, polyethylene terephthalate is preferred. The covering layer may be made of a single material, a mixed system such as a polymer alloy, or a structure in which multiple materials are laminated.

[0023] At least one of the polyethylene terephthalate film (i.e., the support layer) and the coating layer preferably contains particles. At least one of the support layer and the coating layer can contain, for example, one or more types of inorganic or organic particles. Examples of such particles include inorganic particles such as titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, and calcium fluoride, as well as organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based particles. Two or more types of particles may be contained. Examples of inorganic particles include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of organic particles, particularly heat-resistant organic particles, include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine-based particles.

[0024] As the particles, silica particles and / or calcium carbonate particles are more preferably used from the viewpoints of transparency and cost. As the silica particles, porous colloidal silica is preferred. When calcium carbonate particles are used, light calcium carbonate that has been surface-treated with a polyacrylic acid-based polymer compound is preferred from the viewpoint of preventing the lubricant particles from falling off.

[0025] In one embodiment, the raw material for the polyethylene terephthalate film (i.e., the support layer) may be a resin composition obtained by recycling at least the substrate film portion of a film with a functional layer, such as a polyethylene terephthalate resin composition. The average particle size of the particles contained in the polyethylene terephthalate resin composition is preferably 0.2 μm or more and 5.0 μm or less, and more preferably 0.4 μm or more and 5.0 μm or less. When the average particle size is 0.2 μm or more, air can be uniformly released when the film is wound into a roll, both in production and use, resulting in a good wound appearance and good flatness, making it suitable for the production of ultra-thin ceramic green sheets (hereinafter referred to as "good handleability"). When the average particle size is 5.0 μm or less, surface irregularities are reduced, further preventing excessive irregularities from forming on the surface of the processed product (e.g., ceramic green sheet). The average particle size of the particles may be 4.0 μm or less, 3.0 μm or less, 2.0 μm or less, 1.5 μm or less, or 1.0 μm or less. The particles can function as a lubricant. The average particle size of the particles can be measured by the method described in the Examples. The shape of the particles is not particularly limited, and spherical particles or irregular, non-spherical particles can be used as long as the object of the present invention is met. The particle size of irregular particles can be calculated as the equivalent circle diameter. The equivalent circle diameter is calculated by dividing the area of ​​the observed particle by pi (π), calculating the square root, and then multiplying it by two. It is preferable that the coating layer does not substantially contain particles with an average particle size of 1.0 μm or more. It is more preferable that the coating layer does not contain particles with an average particle size of 1.0 μm or more. As described above, at least one of the support layer and the coating layer preferably contains particles, specifically lubricant particles. The length of the longest side of the lubricant particles is preferably 0.5 μm or more and 5.0 μm or less. As may have already been explained, the lubricant particles may be, for example, calcium carbonate particles (CaCO ３or silica particles SiO2. The content of the lubricant particles is preferably 500 ppm or more and 5000 ppm or less relative to the total mass of the laminated polyethylene terephthalate film from the viewpoint of the film's slipperiness and ease of air escape. The lower limit of the content of the lubricant particles is more preferably 600 ppm, and even more preferably 1000 ppm. The upper limit of the content of the lubricant particles is more preferably 4500 ppm, even more preferably 4000 ppm, and particularly preferably 3000 ppm. When the content is 500 ppm or more, good handleability is achieved, which is preferable. When the content is 5000 ppm or less, the formation of excessive irregularities on the surface of the processed product (for example, a ceramic green sheet) can be further prevented. Here, calcium carbonate particles CaCO ３ The content of calcium carbonate particles CaCO ３ The content can be calculated.

[0026] The laminated polyethylene terephthalate film of the present invention may be a biaxially stretched laminated polyethylene terephthalate film. The intrinsic viscosity (IV) of the laminated polyethylene terephthalate film of the present invention is preferably 0.400 dl / g or more and 0.700 dl / g or less, for example, 0.410 dl / g or more and 0.650 dl / g or less, and more preferably 0.430 dl / g or more and 0.620 dl / g or less. It is particularly preferably 0.510 dl / g or more and 0.580 dl / g or less. An intrinsic viscosity of 0.400 dl / g or more is preferred because breakage is less likely to occur during the stretching process. Furthermore, biaxial stretching is possible without impairing film formability. Furthermore, a limiting viscosity of 0.700 dl / g or less is preferred because it provides good cuttability when cutting to a predetermined product width and prevents dimensional defects. Furthermore, the filter filtration pressure can be reduced, thereby preventing operational hurdles. It is preferable to thoroughly vacuum-dry the raw materials.

[0027] The laminated polyethylene terephthalate film according to the present invention desirably exhibits the above-mentioned intrinsic viscosity even in an embodiment in which the film is obtained by forming recycled chips into a film. In one embodiment, the support layer contains 5% by mass to 100% by mass of a resin recycled from a film with a functional layer containing one or more types of inorganic or organic particles. The intrinsic viscosity (IV) of the support layer is preferably 0.50 dl / g to 0.70 dl / g, more preferably 0.51 dl / g to 0.58 dl / g.

[0028] The thickness of the polyethylene terephthalate film (support layer) is preferably 12 to 100 μm, more preferably 12 to 85 μm, and even more preferably 15 μm to 80 μm. A film thickness of 12 μm or more is preferred because there is no risk of deformation due to heat during film production or when used as a process film. On the other hand, a support layer thickness of 100 μm or less is preferred in terms of reducing the environmental load because the amount of film discarded after use is not excessively large, and is also preferred from an economical standpoint because less material per area of ​​the release film is used.

[0029] Next, the thickness of the coating layer is preferably 0.5 μm or more and 8.5 μm or less. Here, the length of the longest side of the lubricant particle is often, for example, 0.1 μm or more and 5.0 μm or less. The lower limit of the thickness of the coating layer is more preferably 0.7 μm, and even more preferably 1.0 μm. The upper limit of the thickness of the coating layer is more preferably 7.5 μm, and even more preferably 6.5 μm. If the thickness of the coating layer is 8.5 μm or less, the lubricant particles on the surface of the support layer may penetrate the coating layer and be exposed from the surface of the coating layer, or the lubricant particles on the surface of the support layer may cause the surface of the coating layer to bulge. As a result, the surface of the coating layer can exhibit slip properties. Therefore, if the coating layer is thicker than 8.5 μm, it is preferable that the coating layer contains lubricant particles. On the other hand, if the thickness of the coating layer is 0.5 μm or more, the coating layer can prevent various particles contained in the support layer from falling off. Here, the various particles are, for example, particles containing one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, or lubricant particles.

[0030] The coating layer is a layer that coats the support layer. The thinner the coating layer, the more susceptible the surface of the coating layer is to the surface of the support layer. Specifically, when the coating layer is 8.5 μm or less in thickness, the surface of the coating layer is more susceptible to the surface of the support layer. That is, when the coating layer is 8.5 μm or less in thickness, the three-dimensional center plane average surface roughness (SRa) and maximum peak height (SRp) of the coating layer surface are more susceptible to the three-dimensional center plane average surface roughness (SRa) and maximum peak height (SRp) of the support layer surface. In the examples of the present application described below, the laminated polyethylene terephthalate film is composed of a layer A (coating layer) / layer B (support layer) / layer A (coating layer) in which the support layer is sandwiched between two coating layers with the same configuration, but this is not limited to this. In practice, the support layer may also be sandwiched between two coating layers with different configurations. That is, in practice, the laminated polyethylene terephthalate film may be composed of an A1 layer (coating layer) / a B layer (supporting layer) / a2 layer (coating layer), where the A1 layer (coating layer) and the A2 layer (coating layer) differ from each other in thickness or material, for example.

[0031] The surface of the coating layer is the surface on which the functional layer is laminated. The three-dimensional center plane average surface roughness (SRa) of this surface is preferably 5 nm or more and 30 nm or less. Furthermore, the maximum peak height (SRp) of this surface is preferably 1000 nm or less. By having such a three-dimensional center plane average surface roughness and maximum peak height, surface irregularities can be suppressed, thereby preventing the transfer of irregularities to the processed product. Preferably, the average surface roughness (SRa) of the surface of the coating layer is 7 nm or more and 30 nm or less, for example, 8 nm or more and 30 nm or less. Having an average surface roughness (SRa) within the above range can also provide high smoothness to the functional layer laminated on the surface, such as a release layer. For example, by controlling the amounts of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements present in the support layer, the three-dimensional center plane average surface roughness (SRa) and maximum peak height (SRp) of the surface of the coating layer can be set within the range of the present invention. When the SRa of a laminated polyethylene terephthalate film is 5 nm or more, the air can be uniformly released when the film is wound into a roll, resulting in a good roll shape and flatness, making it suitable for producing ultra-thin ceramic green sheets. When the SRa is 30 nm or less, surface irregularities can be suppressed, preventing the transfer of irregularities to molded products.

[0032] The coating layer may contain one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, but preferably does not contain these elements.

[0033] The maximum peak height (SRp) of the surface is preferably 1000 nm or less. In one embodiment, the maximum peak height (SRp) of the surface is 100 nm or more and 970 nm or less, and may be 200 nm or more and 950 nm or less. The lower limit of the maximum peak height (SRp) of the surface may be 210 nm or 250 nm. By having the maximum peak height (SRp) be 1000 nm or less, the surface irregularities are reduced, and transfer to the processed product can be suppressed.

[0034] For example, the polyethylene terephthalate film (i.e., the support layer) can be produced using raw materials recycled from a film with a functional layer. The support layer can contain one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and the total amount of these elements can be 0.1 ppm or more relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. Furthermore, it is preferable that the three-dimensional center plane average surface roughness (SRa) of the surface of the coating layer is 5 nm to 30 nm, and the maximum peak height (SRp) is 1,000 nm or less.

[0035] The polyethylene terephthalate film (support layer) contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. The total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is preferably 0.1 ppm or more and 600 ppm or less relative to the total mass of the support layer or the laminated polyethylene terephthalate film. The upper limit of the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is more preferably 480 ppm, even more preferably 200 ppm, and even more preferably 100 ppm, relative to the total mass of the support layer or the laminated polyethylene terephthalate film. The lower limit of the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is preferably 1 ppm, even more preferably 10 ppm, and even more preferably 50 ppm, based on the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. When the total content of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is within the above range, for example, the film formability of the laminated polyethylene terephthalate film is improved, and unevenness on the film surface can be suppressed, preventing the transfer of unevenness to processed products. Conventional recycled films tend to actively remove the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. In contrast, the present invention has found that when the total amount of these elements is a predetermined amount, the laminated polyethylene terephthalate film can maintain good handleability and can suppress unevenness on the film surface, further preventing the transfer of unevenness to molded products. In one embodiment, the unevenness of the film surface can be suppressed to the order of several nanometers to several tens of nanometers, so that the release film can be imparted with good processability and releasability even when used for molding extremely thin ceramic green sheets. Furthermore, the laminated polyethylene terephthalate film of the present invention can exhibit mechanical properties, such as tensile strength and elastic modulus, that are comparable to or higher than those of films formed from virgin materials containing no recycled resin.In this way, by ensuring that the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements is a predetermined amount, the laminated polyethylene terephthalate film can exhibit high recyclability while improving various physical properties.

[0036] The total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements in the support layer is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, more preferably 95 parts by mass or more, even more preferably 98 parts by mass or more, and even more preferably 100 parts by mass, relative to 100 parts by mass of the total amount of these elements in the laminated polyethylene terephthalate film.

[0037] The content of Si element relative to the total mass of the polyethylene terephthalate film or the laminated polyethylene terephthalate film is preferably 600 ppm or less, more preferably 300 ppm or less, and even more preferably 200 ppm or less, and may be, for example, 0.1 ppm or more and 480 ppm or less, or 0.1 ppm or more and 450 ppm or less.

[0038] When the Si element content is within the above range, for example, the laminated polyethylene terephthalate film has good handleability, and furthermore, unevenness on the film surface can be suppressed, and the transfer of unevenness to a molded product can be further prevented. Furthermore, when the Si element content is 0.1 ppm or more, the heat resistance of the polyethylene terephthalate film (i.e., the support layer) is improved. Note that, in one embodiment, the polyethylene terephthalate film can contain 5% by mass or more and 100% by mass or less of a resin obtained by material recycling a film with a functional layer, specifically a release film, and can contain Si elements within the above range.

[0039] In the present invention, the support layer contains 5% by mass or more and 100% by mass or less of a resin obtained by material recycling a film with a functional layer, specifically a release film, and further, the content of Si element relative to the total mass of the polyethylene terephthalate film or the total mass of the laminated polyethylene terephthalate film is within the above range. Therefore, even though the film contains recycled resin, it can exhibit good mechanical properties, such as tensile strength, elasticity, surface hardness, and tear strength. This is presumably because the Si component contributes to the formation of the crystalline structure of the support layer, i.e., the polyethylene terephthalate film. In conventional technology, when material recycling a film with a functional layer, specifically a release film, it was necessary to almost completely remove the silicone component present on the surface of the substrate film.

[0040] The content of Ba element relative to the total mass of the polyethylene terephthalate film or the laminated polyethylene terephthalate film is preferably 600 ppm or less, more preferably 300 ppm or less, and even more preferably 200 ppm or less. For example, it may be 0.1 ppm or more and 480 ppm or less, or 0.1 ppm or more and 450 ppm or less. The same applies to the content of Ti, Ni, Cu, Pt, Pd, Ag, and Au element relative to the total mass of the polyethylene terephthalate film or the laminated polyethylene terephthalate film. The content of each element is preferably 600 ppm or less, more preferably 300 ppm or less, and even more preferably 200 ppm or less. For example, it may be 0.1 ppm or more and 480 ppm or less, or 0.1 ppm or more and 450 ppm or less. In conventional recycled films, the ceramic green sheet component residue, release layer component, electrode member, and base film are completely separated, and only the high-purity polyester resin is used. In contrast, in the present invention, the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements must be within the range of the present invention. The ceramic green sheet component residue, release layer component, electrode member, and base film can be regenerated and reused within the range of the present invention. Therefore, in the present invention, for example, the material recycling process for resins recycled from functional layer-attached films, specifically release films, can be simplified and shortened compared to conventional methods, promoting more efficient recycling with reduced waste.

[0041] The polyethylene terephthalate film (i.e., the support layer) preferably contains one or more of the elements Si, Ti, and Ba. The total amount of Si, Ti, and Ba is preferably 0.1 ppm to 500 ppm relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. The total amount of Si, Ti, and Ba is more preferably 0.3 ppm to 480 ppm, and even more preferably 0.3 ppm to 475 ppm. When the upper limit of the total amount of these elements is 500 ppm, the recycled resin that can be used to produce the support layer may contain some of these elements. In other words, it is acceptable for the recycled resin that can be used to produce the support layer to contain some of these elements. This can improve the recycling yield (see Patent Document 1), specifically, the recycling yield of the recycled resin that can be used to produce the support layer or the laminated polyethylene terephthalate film. When the total amount of Si, Ti, and Ba elements is within the above range, for example, the handling properties of the laminated polyethylene terephthalate film are improved, and furthermore, unevenness on the film surface can be further suppressed, thereby further preventing the transfer of unevenness to processed products, i.e., molded products.

[0042] The total amount of Si, Ti, and Ba elements in the support layer is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, more preferably 95 parts by mass or more, even more preferably 98 parts by mass or more, and even more preferably 100 parts by mass, per 100 parts by mass of the total amount of these elements in the laminated polyethylene terephthalate film.

[0043] The polyethylene terephthalate film (i.e., the support layer) preferably contains one or more of Ti, Ni, Cu, Pt, Pd, Ag, and Au. This reduces the melt resistivity of the laminated polyethylene terephthalate film at 275°C, thereby improving electrostatic adhesion. The total amount of Ti, Ni, Cu, Pt, Pd, Ag, and Au is preferably 10 ppm or more, more preferably 50 ppm or more, and even more preferably 100 ppm or more, based on the total mass of the support layer or the laminated polyethylene terephthalate film.

[0044] The polyethylene terephthalate film (i.e., the support layer) preferably contains one or more of Ni, Cu, Pt, Pd, Ag, and Au. This reduces the melt resistivity of the laminated polyethylene terephthalate film at 275°C, thereby improving electrostatic adhesion. The total amount of Ni, Cu, Pt, Pd, Ag, and Au may be 1 ppm or more, 5 ppm or more, 10 ppm or more, or 20 ppm or more relative to the total mass of the polyethylene terephthalate film or the total mass of the laminated polyethylene terephthalate film. This total amount may be 200 ppm or less, 150 ppm or less, 100 ppm or less, or 80 ppm or less.

[0045] The polyethylene terephthalate film (i.e., the support layer) preferably contains one or more of Ni, Cu, Pt, Pd, Ag, and Au, and Ti, which can further reduce the melt resistivity of the laminated polyethylene terephthalate film at 275°C and thus further improve the electrostatic adhesion.

[0046] The polyethylene terephthalate film (i.e., the support layer) preferably contains one or more of Ni, Cu, Pt, Pd, Ag, and Au elements, as well as Ti, Ba, and Si elements.

[0047] In one embodiment, the melt resistivity (ρi(10 8 The melt resistivity (Ω·cm) is preferably 1.00 or less, more preferably 0.20 or less. When the melt resistivity is 1.00 or less, the laminated polyethylene terephthalate film of the present invention can have excellent electrostatic adhesion. That is, when the melt resistivity is 1.00 or less, the laminated polyethylene terephthalate film of the present invention can have excellent film-forming properties and a high yield.

[0048] In one embodiment, the polyethylene terephthalate film (i.e., the support layer) contains 5% by mass or more and 100% by mass or less of a recycled resin (also referred to as a recycled raw material) based on 100% by mass of the polyethylene terephthalate film (i.e., the support layer). For example, the recycled raw material may be 8% by mass or more and 98% by mass or less, e.g., 10% by mass or more and 95% by mass or less. By containing 5% by mass or more and 100% by mass or less, the amount of petroleum-derived raw materials used can be reduced, making the film environmentally friendly. As the recycled raw material, a resin obtained by recycling a film with a functional layer, specifically a release film, can be used. Alternatively, the resin may be obtained by recycling a release film that has been used and is scheduled to be discarded.

[0049] The functional layer of a recycled functional layer-attached film (i.e., a functional layer-attached film used as a raw material for recycled resin) is not particularly limited and may contain resins such as silicone-based, cyclic olefin-based, acyclic olefin-based, fluorine-based, alkyd-based, acrylic-based, melamine-based, and epoxy-based resins. Preferably, the functional layer contains a silicone-based, acrylic-based, or melamine-based resin. Examples of functional layers include an easy-adhesion layer, an antistatic layer, a release layer, and a pressure-sensitive adhesive layer. Among these, a release layer is preferred, and a silicone release layer is more preferred. In particular, when the functional layer is used as a release layer, residues of processed products may be present on the surface of the release layer. Therefore, to obtain the laminated polyethylene terephthalate film of the present invention, a removal process may be performed, including removing deposits from the functional layer-attached film (details will be described later). Furthermore, the release layer is also required to have high adhesion to the object to be released. For example, release layers for pressure-sensitive adhesives, optical films, and ceramic green sheets can be used in the manufacturing process of the object to be released and the manufacturing process of the device using the same, and therefore must exhibit high adhesion between these processes. Furthermore, the release layer may be a release layer exposed to high temperature (e.g., 60°C or higher) and / or high humidity (e.g., 70% or higher) conditions, or a release layer subjected to high stretching conditions. The removal process, which includes removing the deposits from the functional layer-attached film subjected to these conditions, can increase the purity of the recycled resin and provide, for example, the required optical properties, mechanical strength, etc.

[0050] The silicone-based compound is a compound having a silicone structure in the molecule, and examples thereof include cured silicone, silicone graft resin, and modified silicone resin such as alkyl-modified silicone resin.

[0051] As an example, the present invention provides a method for producing a laminated polyethylene terephthalate film. The production method includes the following steps: (Step 1), (Step 2), (Step 3), and (Step 4). (Step 1) is a pulverization step, which includes pulverizing a functional layer-equipped film to form a pulverized product. (Step 2) is a chipping step, which includes chipping the pulverized product to form recycled chips. (Step 3) is a step of preparing at least recycled chips and polyethylene terephthalate chips other than the recycled chips, so that the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 0.1 ppm or more and 600 ppm or less relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. (Step 4) is a recycled film formation step, which includes melt-extruding a molding material for forming the support layer, which includes the recycled chips and the polyethylene terephthalate chips. In the present invention, by including Steps 1 to 4, a laminated polyethylene terephthalate film can be obtained without impairing its physical properties, even if the method does not include a step of removing deposits from the surface of the functional layer-equipped film. The method for producing a laminated polyethylene terephthalate film may further include a step of removing adhering matter from the film with a functional layer (hereinafter, may be referred to as "step 0"). The method for producing a laminated polyethylene terephthalate film preferably includes step 0. An example of a method for producing a laminated polyethylene terephthalate film will be described in detail below.

[0052] (Step 0: Step of Removing Adherents from Functional Layer-Equipped Film) A functional layer-equipped film to be recycled (i.e., a functional layer-equipped film as a raw material for recycled resin) has a functional layer provided on at least one surface of a substrate film. That is, a functional layer-equipped film includes a substrate film and a functional layer provided on at least one surface of the substrate film. After use of a functional layer-equipped film, adhering matter may remain on the surface of the functional layer-equipped film, for example, the surface of the functional layer or the surface of the substrate film. Furthermore, with regard to functional layer-equipped films, used functional layer-equipped films, functional layer-equipped films that do not meet specifications, functional layer-equipped films that have been damaged during distribution, etc. are usually discarded. It is desirable to perform a step of removing adhering matter from such films to be discarded (i.e., functional layer-equipped films to be discarded) as long as it does not impair the final physical properties of the film. Furthermore, depending on the condition of the adhering matter, the step of removing the adhering matter may be omitted.

[0053] The method for removing deposits from the film with functional layers is not particularly limited. For example, there are methods for removing deposits by attaching an adhesive roll and peeling off the adhesive roll, removing deposits by suction with a vacuum, scraping off deposits with a blade, removing deposits with high-pressure water or high-pressure air, removing deposits by spraying with sand or dry ice, immersing the film with functional layers in a cleaning layer and removing deposits by adsorbing them with microbubbles or the like, floating and removing deposits by micro-vibrations such as ultrasonic waves, and removing deposits by using supercritical CO ２ Examples of such methods include a method of dissolving and removing the deposits by a method using a solvent such as a fluorine-containing solvent. These methods may also be combined. These methods are not particularly limited, but from the standpoint of efficiency, a method that allows roll-to-roll processing is preferred. In this step, some of the functional layer may be removed together with the deposits, or the functional layer may remain on the substrate film without being removed.

[0054] (Step 1: Pulverizing the Film) In step 1, the film with functional layers is pulverized to form a pulverized product. Examples of methods for pulverizing the film with functional layers include pulverizing the film with functional layers itself, and separating the film with functional layers into the functional layer and the base film and then pulverizing them separately or together. Among these, the method of pulverizing the film with functional layers itself is preferred. In the method of separating the film with functional layers into the functional layer and the base film and then pulverizing them separately, the pulverized product of the functional layer and the pulverized product of the base film may or may not be mixed to obtain a pulverized product for producing recycled chips. If not mixed, the pulverized product for producing recycled chips may be a pulverized product of the base film or a pulverized product of the functional layer. The film with functional layers can be pulverized using a pulverizer such as a single-axis pulverizer, a biaxial pulverizer, a triaxial pulverizer, or a cutter mill. Examples of the shape of the pulverized product include flakes, powder, lumps, and strips. Among these, flakes are preferred.

[0055] As described above, the pulverization process can be performed without removing any attachments from the surface of the functional layer-equipped film. Therefore, for example, attachments such as adhesive, ceramic green sheets, and impurities may be present on the surface of the functional layer. Furthermore, some of these attachments may be removed before the pulverization process. By partially removing the attachments, it becomes easier to control the content of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. In other words, the manufacturing method according to an embodiment of the present invention does not require complete removal of attachments such as adhesive, ceramic green sheets, and impurities present on the surface of the functional layer, as in conventional recycling techniques. The manufacturing method according to an embodiment of the present invention does not require removal of the functional layer itself; instead, some of the attachments may be removed to control the content of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. The manufacturing method according to an embodiment of the present invention can directly subject the functional layer and the substrate film, even if such attachments are present, to the pulverization process. Therefore, compared to conventional recycling techniques, the number of steps and time required for producing resin pellets and forming them into a film can be significantly reduced. Furthermore, the amount of waste can be reduced.

[0056] (Step 2: Manufacturing Recycled Chips) The method for manufacturing recycled chips preferably involves granulating the pulverized product by melt extrusion. Examples of granulation equipment include single-screw extruders, twin-screw extruders, and multi-screw extruders. Twin-screw or multi-screw extruders are preferred, as they combine control of mixing intensity and suppress resin degradation. To remove coarse foreign matter, the pulverized product may be passed through a filter between the time it is molten and the time it is extruded. As described above, the polyethylene terephthalate film (i.e., the support layer) contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. Furthermore, the total amount of these elements is 0.1 ppm or more and 600 ppm or less relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. It should be noted that the manufacturing method according to an embodiment of the present invention does not require complete removal of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. The recycled chips are preferably in the form of pellets.

[0057] (Step 3: Preparing Recycled Chips and Polyethylene Terephthalate Chips) In step 3, it is preferable to prepare at least recycled chips and polyethylene terephthalate chips so that the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements is 0.1 ppm or more and 600 ppm or less relative to the total mass of the support layer or the total mass of the laminated polyethylene terephthalate film. The polyethylene terephthalate chips are preferably in the form of pellets. Examples of polyethylene terephthalate in polyethylene terephthalate chips include homopolyethylene terephthalate and copolymerized polyethylene terephthalate. Of these, homopolyethylene terephthalate is preferred. The description of polyethylene terephthalate in polyethylene terephthalate chips will be omitted as it overlaps with the description of polyethylene terephthalate in the functional layer-attached film to be recycled. The polyethylene terephthalate chips may contain particles. The description of particles in polyethylene terephthalate chips will be omitted as it overlaps with the description of particles in the polyethylene terephthalate film. The polyethylene terephthalate chips may contain additives. Examples of the additives include an antioxidant, a light stabilizer, an ultraviolet absorber, and a crystallizing agent. In step 3, additional polyethylene terephthalate chips may be further prepared.

[0058] In step 3, it is preferable to mix at least recycled chips and polyethylene terephthalate chips, thereby obtaining mixed chips containing recycled chips and polyethylene terephthalate chips.

[0059] (Step 4: Step of Producing a Film) In step 4, a molding material for forming the support layer is melt-extruded to obtain a laminated polyethylene terephthalate film. The molding material for forming the support layer contains recycled chips and polyethylene terephthalate chips. In step 4, it is preferable to melt-extrude a mixed chip containing recycled chips and polyethylene terephthalate chips as the molding material for forming the support layer to obtain a laminated polyethylene terephthalate film.

[0060] The film-forming method is not limited, but specifically, recycled polyester pellets and polyethylene terephthalate chips are thoroughly vacuum-dried and mixed, and the mixed chips are then fed into an extruder as a molding material for forming a support layer. The mixed chips are melt-extruded into a sheet at approximately 255 to 280°C and cooled and solidified to form an unstretched polyethylene terephthalate sheet. The resulting unstretched polyethylene terephthalate sheet is stretched 3.0 to 6.0 times in the longitudinal direction using rolls heated to 75 to 140°C to obtain a uniaxially oriented polyethylene terephthalate film. The end of the uniaxially oriented polyethylene terephthalate film is then gripped with clips and introduced into a hot air zone heated to 75 to 140°C, where it is dried and then stretched 3.0 to 6.0 times in the width direction. Subsequently, the film is introduced into a heat-setting zone at 180 to 260°C, where it can be heat-treated for 1 to 60 seconds. During this heat-treatment process, a relaxation treatment of 0 to 10% may be performed in the width or longitudinal direction, if necessary. In order to remove large foreign objects, the recycled chips may be passed through a filter between the time they are melted and the time they are extruded. The finer the mesh of the filter, the more small foreign objects can be removed.

[0061] In step 4, a biaxially oriented laminated polyethylene terephthalate film can be obtained by co-extruding a molding material for forming the support layer (i.e., a mixed chip containing recycled polyester pellets and polyethylene terephthalate chips) and a molding material for forming the coating layer (e.g., polyethylene terephthalate chips), biaxially stretching the unstretched laminated polyethylene terephthalate sheet, and heat-setting it as necessary. The description of the polyethylene terephthalate chips for forming the coating layer overlaps with the description of the polyethylene terephthalate chips for forming the support layer, so this description is omitted. Therefore, the description of the polyethylene terephthalate chips for forming the support layer can also be used as a description of the polyethylene terephthalate chips for forming the coating layer. It is preferable that the molding material for forming the coating layer does not contain recycled chips. In addition, when manufacturing a laminated polyethylene terephthalate fill including a first coating layer, a second coating layer, and a support layer sandwiched between the first and second coating layers, it is preferable to co-extrude a molding material for forming the support layer (i.e., mixed chips including recycled polyester pellets and polyethylene terephthalate chips), a molding material for forming the first coating layer (e.g., polyethylene terephthalate chips), and a molding material for forming the second coating layer (e.g., polyethylene terephthalate chips), and then biaxially stretch the unstretched laminated polyethylene terephthalate sheet and heat-set it as necessary.

[0062] As a result, a laminated polyethylene terephthalate film containing a resin obtained by material recycling of a film with a functional layer can be obtained.

[0063] A method for producing a laminated polyethylene terephthalate film according to an embodiment of the present invention may be described as follows: A method for producing a laminated polyethylene terephthalate film includes: a step of pulverizing a functional layer-equipped film; a step of melt-extruding the pulverized product formed by pulverizing the functional layer-equipped film to form recycled chips; and a step of co-extruding at least a first molding material for forming a support layer and a second molding material for forming a coating layer, wherein the first molding material includes recycled chips and the first polyethylene terephthalate chips, and the second molding material includes the second polyethylene terephthalate chips. In the step of co-extruding the first molding material and the second molding material, it is preferable to supply the first molding material to a first extruder and the second molding material to a second extruder, and then laminate them to extrude a sheet-like molten material. The production method according to an embodiment of the present invention preferably further includes a step of cooling and solidifying the sheet-like molten material. The production method according to an embodiment of the present invention preferably further includes a step of biaxially stretching an unstretched laminated polyethylene terephthalate sheet obtained by cooling and solidifying the sheet-like molten material. The production method according to an embodiment of the present invention may further include a step of removing any adhering material from the functional layer-equipped film. When manufacturing a laminated polyethylene terephthalate fill including a first covering layer, a second covering layer, and a support layer sandwiched between the first and second covering layers, at least a first molding material for forming the support layer, a second molding material for forming the first covering layer, and a third molding material for forming the second covering layer can be co-extruded. In this case, the third molding material can be supplied to a third extruder. The third molding material can include third polyethylene terephthalate chips.

[0064] (Resin Sheet) In one embodiment, the laminated polyethylene terephthalate film of the present invention can be used as a substrate film in a release film for molding a resin sheet. The resin sheet is not particularly limited, and may be used in the production of adhesives and optical films. In one embodiment, the release film for molding a resin sheet contains an inorganic compound. Examples of inorganic compounds include metal particles, metal oxides, and minerals, such as calcium carbonate, silica particles, aluminum particles, and barium titanate particles. Examples of resins include polyvinyl acetal resin and poly(meth)acrylic acid ester resin. The laminated polyethylene terephthalate film of the present invention is suitable for laminating a highly smooth release layer. Even in an embodiment in which the resin sheet contains these inorganic compounds, defects attributable to inorganic compounds, such as breakage of the resin sheet and difficulty in peeling the resin sheet from the release layer, can be suppressed. The resin components forming the resin sheet can be appropriately selected depending on the application. In one embodiment, the resin sheet containing an inorganic compound is a ceramic green sheet. For example, the ceramic green sheet may contain barium titanate as the inorganic compound. In one embodiment, the resin sheet has a thickness of 0.2 μm or more and 1.0 μm or less.

[0065] (Release Film) In one embodiment, the release film of the present invention comprises a laminated polyethylene terephthalate film and a release layer. The release layer is provided on the surface of the coating layer of the laminated polyethylene terephthalate film. That is, the release film comprises a laminated polyethylene terephthalate film and a release layer laminated on the surface of the coating layer of the laminated polyethylene terephthalate film.

[0066] The description of the release layer of the release film will be omitted because it overlaps with the description of the release layer of the above-mentioned functional layer-attached film (i.e., the recycled functional layer-attached film). Therefore, the description of the release layer of the above-mentioned functional layer-attached film can also be used as a description of the release layer of the release film according to the present invention. The release layer may be provided on the surface of the coating layer by a so-called in-line coating method in which the release layer is applied during the film formation of the laminated polyethylene terephthalate film, or may be provided on the surface of the coating layer after the laminated polyethylene terephthalate film is produced.

[0067] In the above-described embodiment, the support layer contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and the total amount of these elements is 0.1 ppm to 600 ppm relative to the total mass of the support layer or the laminated polyethylene terephthalate film. However, the laminated polyethylene terephthalate film of the present invention is not limited to this.

[0068] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The property values ​​used in the present invention were evaluated using the following methods.

[0069] (1) Intrinsic Viscosity (IV) A film (specifically, a laminated polyethylene terephthalate film) or a polyester resin (specifically, recycled PET1-7, PET10, or MB11) was pulverized and dried, and then dissolved in a mixed solvent of phenol / tetrachloroethane = 60 / 40 (mass ratio). The solution was centrifuged to remove inorganic particles, and then an Ubbelohde viscometer was used to measure the flow time of a solution with a concentration of 0.4 (g / dl) at 30°C and the flow time of the solvent alone. The intrinsic viscosity was calculated from the ratio of these times using the Huggins equation, assuming that the Huggins constant was 0.38.

[0070] (2) Si and Ti analysis As a pretreatment, approximately 1 g of sample (specifically, laminated polyethylene terephthalate film, recycled PET1-7, PET10, MB11) was taken, and 15 ml of nitric acid, 3 ml of ultrapure water, and 0.1 ml of hydrofluoric acid were added to the sample, and the sample was dissolved in acid using a microwave sample decomposition device (UltraWAVE manufactured by Milestone Corporation). The amount of Si and Ti elements was then measured using an ICP optical emission spectrometer (SPECTRO BLUE TI manufactured by SPECTRO Corporation).

[0071] (3) Analysis of Ba, Ni, Cu, Pd, Ag, Au, and Pt As a pretreatment, approximately 0.5 g of sample (specifically, laminated polyethylene terephthalate film, recycled PET1-7, PET10, and MB11) was taken, carbonized, and incinerated. The residue was dissolved in 1.2 N hydrochloric acid to prepare the measurement sample. The amounts of Ba, Ni, Cu, Pd, Ag, Au, and Pt were then measured using an ICP optical emission spectrometer (SPECTRO BLUE TI, manufactured by SPECTRO).

[0072] (4) Ca analysis As a pretreatment, approximately 0.5 g of sample (specifically, laminated polyethylene terephthalate film, recycled PET1-7, PET10, MB11) was collected, carbonized, and incinerated. The residue was dissolved in 1.2 N hydrochloric acid to prepare a measurement sample. Then, the amount of Ca element was measured using an ICP optical emission analyzer (SPECTRO BLUE TI manufactured by SPECTRO). By measuring the content of Ca element, the amount of calcium carbonate particles, CaCO ３ The content was calculated.

[0073] (5) Surface Roughness (SRa, SRp) The surface of the outermost layer (specifically, Layer A) of the laminated polyethylene terephthalate film was measured using a stylus-type three-dimensional roughness meter (SE-3AK, manufactured by Kosaka Laboratory Co., Ltd.). Under conditions of a needle radius of 2 μm and a load of 30 mg, measurements were taken over a measurement length of 1 mm in the longitudinal direction of the laminated polyethylene terephthalate film with a cutoff value of 0.25 mm and a needle feed rate of 0.1 mm / sec. The measurement was divided into 500 points at a 2 μm pitch, and the height of each point was captured into a three-dimensional roughness analyzer (SPA-11). A similar operation was performed continuously 150 times at 2 μm intervals across the width of the laminated polyethylene terephthalate film, i.e., over a width of 0.3 mm of the laminated polyethylene terephthalate film, and the data was captured into the analyzer. The center surface average roughness (SRa) and centerline peak height (SRp) were then determined using the analyzer.

[0074] (6) Average particle size The surface-roughening agent was observed with a scanning electron microscope (S-51O type, manufactured by Hitachi, Ltd.), and the magnification was appropriately changed depending on the particle size, and the photographs were enlarged and copied. Next, the periphery of each of at least 200 randomly selected particles was traced, and the circle-equivalent diameter of the particles was measured from these traced images using an image analyzer, and the average of these was taken as the average particle size.

[0075] (7) Evaluation of MLCC processability After forming a silicone-based release layer as a functional layer on the target laminated polyethylene terephthalate film, ceramic green sheets were produced and the defect rate due to the laminated polyethylene terephthalate film was evaluated. Specifically, the defect rate was evaluated using the following procedure.

[0076] (Preparation of Release Film) A coating film (wet amount) of 5 g / m2 was applied to the A layer of a laminated polyethylene terephthalate film. ２ The coating solution described below was applied by reverse gravure so that the film thickness was 100°C, and then 0.5 seconds after application, the film was dried at 100°C for 2 seconds (hereinafter, sometimes referred to as "initial drying"). Without any gap after the initial drying (i.e., continuously from the initial drying), the film was heated at 130°C for 7 seconds, and then 8 seconds after this heating was completed, the film was wound into a roll. In this way, 100 sheets of release film were produced for each example.

[0077] (Coating Liquid Used to Prepare Release Film) The composition of the coating liquid used to prepare the release film is as follows. The solid content of the coating liquid was 1.0% by mass, the surface tension was 27 mN / m, and the viscosity was 5 mPa·s. This coating liquid was used after passing through a filter capable of removing 99% or more of foreign matter of 0.5 μm or larger. Methyl ethyl ketone: 57.93 parts by mass Toluene: 40.00 parts by mass Resin solution A (a long-chain alkyl group-containing acrylic polyol solution with a solid content of 40% by mass. The preparation method will be described later.) 1.75 parts by mass Crosslinking agent (hexamethoxymethylolmelamine, solid content 100% by mass) 0.25 parts by mass Silicone-based release agent (polyether-modified polydimethylsiloxane, TSF4446, solid content 100% by mass, manufactured by Momentive) 0.05 parts by mass Acid catalyst (paratoluenesulfonic acid) 0.02 parts by mass

[0078] (Preparation of Resin Solution A) Stearyl (meth)acrylate, hydroxyethyl (meth)acrylate, and methyl (meth)acrylate were mixed in a ratio of 20 mol% to 40 mol% and then diluted with toluene to a solids concentration of 40% by mass. 0.5 mol% azobisisobutyronitrile was added under a nitrogen stream to copolymerize the mixture. This resulted in a resin solution A (i.e., a long-chain alkyl group-containing acrylic polyol solution) with a solids content of 40% by mass. The weight-average molecular weight of the resulting polymer was 30,000. (Preparation of Ceramic Green Sheet) The following materials were mixed and stirred, and then dispersed for 60 minutes using a bead mill with 0.5 mm diameter zirconia beads as the dispersoid. This resulted in a ceramic slurry. Toluene 43.75 parts by mass Ethanol 43.75 parts by mass Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 10.86 parts by mass Polyvinyl butyral (S-LEC BM-S manufactured by Sekisui Chemical Co., Ltd.) 1.09 parts by mass DOP (dioctyl phthalate) 0.55 parts by mass The ceramic slurry was applied to the release layer of a release film with an applicator so that the thickness of the ceramic green sheet was 1.0 μm, and then dried at 90 ° C. for 2 minutes. In this way, a ceramic green sheet was produced on the release film. Note that 100 ceramic green sheets were produced in each example.

[0079] (Determination of Pass / Fail) After peeling the ceramic green sheet from the release film, the arithmetic mean roughness Ra and maximum protrusion height Rp of the peeled surface of the ceramic green sheet (i.e., the surface of both sides of the ceramic green sheet that was in contact with the release film) were measured, and the pass / fail was determined according to the following criteria. Ra and Rp were measured using a scanning white light interference microscope "Vertscan VS1530" manufactured by Hitachi High-Technologies Corporation. Good: Ra less than 30 nm and Rp less than 1000 nm. Poor: Ra 30 nm or more or Rp 1000 nm or more. (Calculation of Defective Rate) The defective rate for each example was calculated using the following formula: Defective rate (%) = (number of ceramic green sheets determined to be defective / 100 sheets) x 100. The defective rate for each example is shown in Table 3 according to the following classification. Good: Defective rate 3% or less. Fair: Defective rate more than 3% but 5% or less. X: Defective rate more than 5%.

[0080] (8) Wrinkles on Winding The number of convex wrinkles caused by air infiltration visible on the surface of a laminated polyethylene terephthalate film roll having a thickness of 25 μm, a width of 1400 mm, and a length of 8000 m was observed per product (i.e., per laminated polyethylene terephthalate film roll) and evaluated using the following criteria: ◯: 0 to 10 wrinkles or less △: 11 to 20 wrinkles or less ×: 21 wrinkles or more

[0081] (9) Melt Resistivity A sample of a laminated polyethylene terephthalate film before stretching was prepared. Two electrodes (stainless steel wires with a diameter of 0.6 mm) were placed on both ends of the sheet before stretching, and the sheet was sandwiched between two quartz plates with a width of 2 cm to form a uniform layer of molten polyester composition with a width of 2 cm and a thickness of 0.6 mm. A DC voltage of 120 V was applied under a temperature condition of 275°C, and the current (io) was measured. This was then applied to the following equation to obtain the melt resistivity value ρi(10 8 The resistance (Ω cm) was calculated. ρi (Ω cm) = (A / L) × (V / io) [A: electrode area, L: distance between electrodes (cm), V: voltage (V)] A (cm ２) = [width of molten polyester composition layer] x [thickness] = 2 (cm) x 0.06 (cm), and V = 120 (V). L is a value measured without including the diameter of the electrode, and is 1.3 cm. Evaluation was performed using the following criteria. Electrostatic adhesion S: melt specific resistance value of 0.20 or less Electrostatic adhesion A: melt specific resistance value greater than 0.20 and less than 1.00 Electrostatic adhesion B: melt specific resistance value greater than 1.00

[0082] (Preparation of Recycled PET1) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was used. This film was placed in a single-screw grinder and pulverized using a 4 mm aperture screen at a rate of 1000 kg / hour to obtain a pulverized film. The resulting pulverized film was fed into a single-screw extruder to obtain Recycled PET1. The intrinsic viscosity of Recycled PET1 was 0.57 dl / g and the Si concentration was 150 ppm. The evaluation results and various conditions are shown in Table 1.

[0083] (Preparation of Recycled PET2) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was used. This film was placed in a single-screw grinder and pulverized using a 4 mm aperture screen at a rate of 100 kg / hour to obtain a pulverized film. The resulting pulverized film was fed into a twin-screw extruder to obtain Recycled PET2. The intrinsic viscosity of Recycled PET2 was 0.57 dl / g and the Si concentration was 150 ppm. The evaluation results and various conditions are shown in Table 1.

[0084] (Preparation of Recycled PET3) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was prepared. This PET film (i.e., a PET film having a silicone-based release layer) was used in the production of a multilayer ceramic capacitor. In the production of the multilayer ceramic capacitor, a ceramic green sheet was formed on the silicone-based release layer of this PET film (i.e., a PET film having a silicone-based release layer), electrodes were printed on the ceramic green sheet, and the PET film was wound into a roll. In the production of the multilayer ceramic capacitor, the PET film was unwound and the ceramic green sheet was peeled from the PET film. This used PET film was placed in a dry peeling device, and the resulting bale-like PET film was placed in a single-screw crusher and crushed using a 4 mm aperture screen at a rate of 100 kg / hour to obtain a crushed film. The resulting crushed product was placed in a twin-screw extruder to obtain Recycled PET3. The intrinsic viscosity of the recycled PET3 was 0.56 dl / g, the Si concentration was 50 ppm, the Ti concentration was 170 ppm, the Ba concentration was 570 ppm, and the Ni concentration was 60 ppm. The evaluation results and various conditions are shown in Table 1.

[0085] (Preparation of Recycled PET4) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was prepared. This PET film (i.e., a PET film having a silicone-based release layer) was used in the production of a multilayer ceramic capacitor. In the production of the multilayer ceramic capacitor, a ceramic green sheet was formed on the silicone-based release layer of this PET film (i.e., a PET film having a silicone-based release layer), electrodes were printed on the ceramic green sheet, and the PET film was wound into a roll. In the production of the multilayer ceramic capacitor, the PET film was unwound and the ceramic green sheet was peeled from the PET film. This used PET film was placed in a dry peeling device, and the resulting bale-like PET film was placed in a single-screw crusher and crushed using a 4 mm aperture screen at a rate of 100 kg / hour to obtain a crushed film. The resulting crushed product was placed in a twin-screw extruder to obtain Recycled PET4. The recycled PET4 had an intrinsic viscosity of 0.55 dl / g, a Si concentration of 50 ppm, a Ti concentration of 170 ppm, a Ba concentration of 570 ppm, and a Cu concentration of 60 ppm. The evaluation results and various conditions are shown in Table 1.

[0086] (Preparation of Recycled PET5) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was prepared. This PET film (i.e., a PET film having a silicone-based release layer) was used in the production of a multilayer ceramic capacitor. In the production of the multilayer ceramic capacitor, a ceramic green sheet was formed on the silicone-based release layer of this PET film (i.e., a PET film having a silicone-based release layer), electrodes were printed on the ceramic green sheet, and the PET film was wound into a roll. In the production of the multilayer ceramic capacitor, the PET film was unwound and the ceramic green sheet was peeled from the PET film. This used PET film was placed in a dry peeling device, and the resulting bale-like PET film was placed in a single-screw crusher and crushed using a 4 mm aperture screen at a rate of 100 kg / hour to obtain a crushed film. The resulting crushed product was placed in a twin-screw extruder to obtain Recycled PET5. The intrinsic viscosity of the recycled PET5 was 0.55 dl / g, the Si concentration was 50 ppm, the Ti concentration was 170 ppm, the Ba concentration was 570 ppm, the Pd concentration was 30 ppm, and the Ag concentration was 30 ppm. The evaluation results and various conditions are shown in Table 1.

[0087] (Preparation of Recycled PET6) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was prepared. This PET film (i.e., a PET film having a silicone-based release layer) was used in the production of a multilayer ceramic capacitor. In the production of the multilayer ceramic capacitor, a ceramic green sheet was formed on the silicone-based release layer of this PET film (i.e., a PET film having a silicone-based release layer), electrodes were printed on the ceramic green sheet, and the PET film was wound into a roll. In the production of the multilayer ceramic capacitor, the PET film was unwound and the ceramic green sheet was peeled off from the PET film. This used PET film was placed in a dry peeling device, and the resulting bale-like PET film was placed in a single-screw crusher and crushed using a 4 mm aperture screen at a rate of 100 kg / hour to obtain a crushed film. The resulting crushed product was placed in a twin-screw extruder to obtain Recycled PET6. The recycled PET6 had an intrinsic viscosity of 0.54 dl / g, a Si concentration of 50 ppm, a Ti concentration of 170 ppm, a Ba concentration of 570 ppm, and a Au concentration of 60 ppm. The evaluation results and various conditions are shown in Table 1.

[0088] (Preparation of Recycled PET7) A used PET film having a silicone-based release layer on one side and containing 2000 ppm of calcium carbonate with a particle size of 0.6 μm was prepared. This PET film (i.e., a PET film having a silicone-based release layer) was used in the production of a multilayer ceramic capacitor. In the production of the multilayer ceramic capacitor, a ceramic green sheet was formed on the silicone-based release layer of this PET film (i.e., a PET film having a silicone-based release layer), electrodes were printed on the ceramic green sheet, and the PET film was wound into a roll. In the production of the multilayer ceramic capacitor, the PET film was unwound and the ceramic green sheet was peeled from the PET film. This used PET film was placed in a dry peeling device, and the resulting bale-like PET film was placed in a single-screw crusher and crushed using a 4 mm aperture screen at a rate of 100 kg / hour to obtain a crushed film. The resulting crushed product was placed in a twin-screw extruder to obtain Recycled PET7. The intrinsic viscosity of the recycled PET7 was 0.53 dl / g, the Si concentration was 50 ppm, the Ti concentration was 170 ppm, the Ba concentration was 570 ppm, and the Pt concentration was 60 ppm. The evaluation results and various conditions are shown in Table 1.

[0089] (Preparation of Polyethylene Terephthalate Pellets (PET10)) A continuous esterification reactor consisting of a three-stage complete mixing vessel equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet was used. The TPA rate was 2 ton / hr, EG was 2 moles per mole of TPA, and antimony trioxide was added in an amount such that the Sb atom concentration in the resulting PET was 160 ppm. These slurries were continuously fed to the first esterification reactor of the esterification reactor and reacted at 255°C under atmospheric pressure for an average residence time of 4 hours. The reaction product in the first esterification reactor was then continuously removed from the system and fed to a second esterification reactor. EG distilled off from the first esterification reactor was fed to the second esterification reactor in an amount of 8% by mass relative to the resulting polymer (the resulting PET). Further, an EG solution containing magnesium acetate in an amount to give 65 ppm of Mg atoms relative to the produced PET and an EG solution containing TMPA in an amount to give 20 ppm of P atoms relative to the produced PET were added, and the reaction was carried out at atmospheric pressure for an average residence time of 1.5 hours at 260°C. The reaction product in the second esterification reactor was then continuously removed from the system and fed to a third esterification reactor. An EG solution containing TMPA in an amount to give 20 ppm of P atoms relative to the produced PET was then added, and the reaction was carried out at atmospheric pressure for an average residence time of 0.5 hours at 260°C. The esterification reaction product produced in the third esterification reactor was continuously fed to a three-stage continuous polycondensation reactor for polycondensation, and then filtered through a stainless steel sintered filter medium (nominal filtration accuracy: 90% cutoff for 5 μm particles). This resulted in the production of polyethylene terephthalate pellets, PET10, with an intrinsic viscosity of 0.62 dl / g. The evaluation results and various conditions are shown in Table 1.

[0090] (Preparation of polyethylene terephthalate calcium carbonate masterbatch (MB11)) PET10 and calcium carbonate particles having an average particle size of 0.6 μm were melted and kneaded in a twin-screw extruder to prepare a masterbatch with a calcium carbonate particle concentration of 16,000 ppm. The evaluation results and various conditions are shown in Table 1.

[0091] Example 1: After drying, each of the above PETs was melted at 290°C in a melt extruder. Two-stage filtration was performed: a filter made of sintered stainless steel fibers with a 95% cut diameter of 15 μm, and a filter made of sintered stainless steel particles with a 95% cut diameter of 15 μm. The resulting mixture was then merged in a feed block and laminated to form a layer B (support layer) composed of 43.8% PET10, 6.2% MB11, and 50% recycled PET1, and a layer A (covering layer) composed of 100% PET10. The resulting mixture was extruded (cast) into a sheet at a speed of 45 m / min, electrostatically bonded to a casting drum at 30°C, and cooled to obtain an unstretched polyethylene terephthalate sheet. The layer ratio (i.e., thickness ratio) was adjusted to Layer A / Layer B / Layer A = 6% / 88% / 6% based on the output rate of each extruder.

[0092] The electrostatic adhesion conditions were as follows: electrode material was tungsten, cylindrical (wire) with a diameter of 0.2 mm and a length of 0.5 m, current was controlled to be constant at 5 mA, electrode tension was 5 kg, and electrode renewal speed was 5 m / hour.

[0093] Next, this unstretched polyethylene terephthalate sheet was heated with an infrared heater and then stretched 3.5 times in the machine direction at a roll temperature of 80°C using the speed difference between the rolls. Thereafter, it was introduced into a tenter and stretched 4.2 times in the transverse direction at 140°C. It was then heat-treated at 210°C in a heat-setting zone. It was then subjected to a 2.3% relaxation treatment in the transverse direction at 170°C to obtain a mill roll (5.0 m wide) of laminated polyethylene terephthalate film having a thickness of 25 μm.

[0094] This mill roll was transferred to a slitter and processed using a static eliminator (Kasuga Electric Co., Ltd., high-density static elimination processing system) and a web cleaner (Shinko Co., Ltd., ultrasonic cleaner system). It was then cut to a width of 1,400 mm. A core material with an inner diameter of 6 inches, a thickness of 12 mm, a moisture content of 8%, a surface roughness (SRa = 4.3 nm, SRp = 41.4 nm), and a flattening compressive strength of 200 kg / 100 mm and a resin-impregnated paper was attached. A length of 8,000 m was wound at a maximum speed of 400 m / min using a contact roll with a rubber hardness of 60 degrees, with a contact surface pressure of 200 kg / m and a tension of 15 MPa. This resulted in a laminated polyethylene terephthalate film roll. A laminated polyethylene terephthalate film was cut from the laminated polyethylene terephthalate film roll and subjected to various evaluations. This laminated polyethylene terephthalate film was a film composed of Layer A (coating layer), Layer B (supporting layer), and Layer A (coating layer) laminated in this order. The evaluation results are shown in Tables 2 and 3.

[0095] The dust level in the atmosphere during the film manufacturing process was Class 1000.

[0096] (Examples 2 and 3) The layer ratio was changed from Example 1 to obtain a laminated polyethylene terephthalate film roll shown in Table 2. A laminated polyethylene terephthalate film was cut out from the laminated polyethylene terephthalate film roll and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0097] (Examples 4 to 10) The materials were changed from Example 1 to obtain laminated polyethylene terephthalate film rolls shown in Table 2. Laminated polyethylene terephthalate films were cut out from the laminated polyethylene terephthalate film rolls and subjected to various evaluations. The evaluation results are shown in Tables 2 and 3.

[0098] Comparative Examples 1 and 3: The materials used in Example 1 were changed to obtain laminated polyethylene terephthalate film rolls shown in Table 2. Laminated polyethylene terephthalate films were cut out from the laminated polyethylene terephthalate film rolls and subjected to various evaluations. The evaluation results are shown in Tables 2 and 3.

[0099] Comparative Example 2 The layer ratio was changed from that of Example 1 to obtain a laminated polyethylene terephthalate film roll shown in Table 2. A laminated polyethylene terephthalate film was cut out from the laminated polyethylene terephthalate film roll and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0100] Ceramic green sheets were produced using the laminated polyethylene terephthalate films of the Examples, and the defect rate due to the laminated polyethylene terephthalate film was evaluated. The defect rate was suppressed to 3% or less, indicating the production of good ceramic green sheets. Furthermore, the use of recycled film enabled the production of environmentally friendly products (specifically, laminated polyethylene terephthalate films and release films). The laminated polyethylene terephthalate films of the Examples exhibited performance equivalent to, for example, the laminated polyethylene terephthalate film of Comparative Example 1 (i.e., a laminated polyethylene terephthalate film without recycled PETs 1-7). Comparative Example 1 does not contain any Si, Ti, Ba, Ni, Cu, Pd, Ag, Au, or Pt elements, and is outside the scope of the present invention. Comparative Example 1 does not use recycled PETs 1-7, and therefore does not contribute to reducing environmental impact. Comparative Example 2 had a three-dimensional center plane average surface roughness (SRa) below the range of the present invention, resulting in the occurrence of wrinkles during winding. Therefore, Comparative Example 2 had inferior handleability compared to Examples 1-10. In Comparative Example 3, the three-dimensional center plane average surface roughness (SRa) and maximum peak height (SRp) exceeded the ranges of the present invention, and the MLCC processability was insufficient.

[0101]

[0102] In Table 2, "MB" indicates a polyethylene terephthalate masterbatch containing calcium carbonate.

[0103] The concentration of each element in Table 3, that is, the content of each element, is the content relative to the total mass of the laminated polyethylene terephthalate film.

[0104] The laminated polyethylene terephthalate film of the present invention can suppress the transfer of the surface shape to a processed product even when produced using a recycled resin containing one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. Therefore, the present invention has industrial applicability.

Claims

1. A laminated polyethylene terephthalate film comprising a support layer made of a polyethylene terephthalate film and a coating layer having a surface for laminating a functional layer, wherein the support layer contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and the total amount of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au is 0.1 ppm or more and 600 ppm or less with respect to the total mass of the laminated polyethylene terephthalate film, and the coating layer is a layer containing a polyester resin, and the laminated polyethylene terephthalate film satisfies at least one of the following requirements (1) and (2): (1) The three-dimensional center plane average surface roughness (SRa) of the surface is 5 nm or more and 30 nm or less. (2) The maximum peak height (SRp) of the surface is 1000 nm or less.

2. The laminated polyethylene terephthalate film according to claim 1, wherein the support layer contains one or more of Si, Ti, and Ba, and the total amount of Si, Ti, and Ba is 0.1 ppm or more and 500 ppm or less relative to the total mass of the laminated polyethylene terephthalate film.

3. The laminated polyethylene terephthalate film according to claim 1, wherein the thickness of the coating layer is from 0.5 μm to 8.5 μm.

4. Melting resistivity at 275℃ (ρi(10 8 2. The laminated polyethylene terephthalate film according to claim 1, having a compressive strength (Ω·cm) of 1.00 or less.

5. The laminated polyethylene terephthalate film according to claim 1, wherein the support layer contains one or more of Ti, Ni, Cu, Pt, Pd, Ag, and Au elements, and the total amount of Ti, Ni, Cu, Pt, Pd, Ag, and Au elements is 10 ppm or more relative to the total mass of the laminated polyethylene terephthalate film.

6. The laminated polyethylene terephthalate film according to claim 1, wherein the content of silicon element is 300 ppm or less based on the total mass of the laminated polyethylene terephthalate film.

7. The laminated polyethylene terephthalate film according to claim 1, wherein the content of Ba element is 300 ppm or less based on the total mass of the laminated polyethylene terephthalate film.

8. The laminated polyethylene terephthalate film according to claim 1, wherein the support layer contains 5% by mass or more and 100% by mass or less of a resin obtained by material recycling and / or chemical recycling of a film with a functional layer.

9. The laminated polyethylene terephthalate film according to claim 1, wherein at least one of the support layer and the covering layer contains lubricant particles, and the content of the lubricant particles is 500 ppm or more and 5,000 ppm or less relative to the total mass of the laminated polyethylene terephthalate film.

10. The laminated polyethylene terephthalate film according to claim 1, wherein the intrinsic viscosity (IV) of the supporting layer is 0.400 dl / g or more and 0.700 dl / g or less.

11. A release film comprising: a laminated polyethylene terephthalate film according to any one of claims 1 to 10; and a functional layer provided on the surface of the coating layer provided on the laminated polyethylene terephthalate film, wherein the functional layer is a release layer.

12. A method for producing the laminated polyethylene terephthalate film according to any one of claims 1 to 10, comprising the steps of: a pulverization step comprising pulverizing a polyethylene terephthalate film having a functional layer to form a pulverized product. chipping the ground product to form recycled chips. A recycled film forming process including melt-extruding a molding material for forming the support layer, the molding material including the recycled chips and polyethylene terephthalate chips different from the recycled chips.