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

Abstract

Provided is a laminated polyethylene terephthalate film capable of suppressing transfer of a surface shape to a processed product even when a recycled resin is used. The laminated polyethylene terephthalate film includes a first cover layer, an intermediate layer, and a second cover layer. The first cover layer has a surface for laminating a functional layer. The intermediate layer contains one or more of Si element, Ti element, Ba element, Ni element, Cu element, Pt element, Pd element, Ag element, and Au element. The total amount of the Si element, the Ti element, the Ba element, the Ni element, the Cu element, the Pt element, the Pd element, the Ag element, and the Au element is 0.1 ppm or more and 5,000 ppm or less with respect to the total mass of the intermediate layer. The laminated polyethylene terephthalate film satisfies at least any one of conditions (1) and (2). (1) The three-dimensional center plane average surface roughness of the aforementioned surface is 1 nm or more and 7.5 nm or less. (2) The maximum peak height of the aforementioned surface is 220 nm or less.

Description

Technical Field

[0001] This invention relates to laminated polyethylene terephthalate films, release films, and methods for manufacturing laminated polyethylene terephthalate films. Background Technology

[0002] Films containing functional layers with various functions on the surface of substrates such as synthetic resins (hereinafter sometimes referred to as process films) are used in fields such as electronic components, optical components, labeling, and mold release. Films used in process films, films that do not meet standards, and films damaged during distribution are usually discarded (hereinafter sometimes referred to as films destined for waste).

[0003] Patent Document 1 discloses a method for determining the amount of impurities in a used film, a method for reusing a used film, and a method for making a film from the reused raw material.

[0004] For example, Patent Document 1 discloses removing a release layer containing organosilicon, barium titanate, and adhesive formed on the surface of a substrate film as residues.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-115862 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] For efficient resource utilization, it is preferable to reuse pre-discarded films. In particular, the circulation of films with functional layers and substrate films (i.e., films with functional layers), such as release films, has tended to increase in recent years, and the amount of waste has also increased accordingly. Therefore, there is a demand for the construction of a circular reuse system for release films. That is, it is required to utilize pre-discarded release films in the manufacture of release films.

[0010] In addition, in the construction of circular reuse, the reuse yield becomes an important item.

[0011] The technology in Patent Document 1 exhibits the following tendency: the recycling yield varies depending on the amount of impurities contained in the film, and the recycling yield deteriorates as the amount of impurities increases. For example, in the technology of Patent Document 1, when the total weight of the film is set to 100 wt%, and the amount of impurities in the film is 0.2 wt% or more, thermal recycling is applied. In this case, the recycling yield is 0.

[0012] Furthermore, from the perspective of surface transfer printing on processed products, a low surface roughness of the release film is always required, and the same applies to reusable films. Processed products include, for example, resin sheets such as ceramic green sheets, laminated ceramic capacitors formed from ceramic green sheets, semiconductor components, or optical films.

[0013] However, in the technology of Patent Document 1, although there is a record of the amount of impurities, there is no record of the surface roughness of the film, leaving the question of whether the surface roughness will meet the expectations.

[0014] Therefore, the object of the present invention is to provide a laminated polyethylene terephthalate film, a method for manufacturing the same, and a release film capable of suppressing the transfer of surface shapes to processed articles. A preferred embodiment of the invention relates to a laminated polyethylene terephthalate film, a method for manufacturing the same, and a release film, wherein the laminated polyethylene terephthalate film exhibits excellent recycling yield even when using recycled resins from pre-determined waste films, particularly films with functional layers, such as release films, and is capable of suppressing the transfer of surface shapes to processed articles. The recycled resin comprises one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0015] Solution for solving the problem

[0016] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by using a system containing impurities of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag and Au elements in the recycled film, the surface roughness can be successfully controlled within a specified range, thereby solving the above-mentioned problems and completing the present invention.

[0017] More specifically, in recent years, the necessity for reducing environmental burden, represented by SDGs and carbon neutrality, has further increased. Therefore, the inventors have conducted in-depth research on improving the recycling yield of process films, such as release films, and found that, for process films, in order to improve the recycling yield, among various factors, it is necessary to control the recycling process of process films.

[0018] However, for example, if the recycling yield is simply increased, the required properties of the process film, etc., may become insufficient.

[0019] Therefore, when using laminated polyethylene terephthalate films as process films, such as as substrate films for release films, it is necessary to achieve a good balance between improving the peelability of the processed product and suppressing the transfer of the surface shape caused by the process film on the processed product.

[0020] In addition, it is required that films containing particles be reused.

[0021] In view of this situation, the inventors have developed a laminated polyethylene terephthalate film, a method for manufacturing the film, and a release film thereof, which can suppress the transfer of surface shape to the processed article even when using a recycled resin containing one or more of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements.

[0022] The present invention provides the following methods.

[0023] [Item 1]

[0024] A laminated polyethylene terephthalate film comprising: a first cover layer containing polyethylene terephthalate resin, an intermediate layer containing polyethylene terephthalate resin, and a second cover layer containing polyester resin.

[0025] The aforementioned first cover layer has a surface for stacking functional layers.

[0026] The aforementioned intermediate layer contains one or more of the following elements: Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0027] The total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the aforementioned intermediate layer is between 0.1 ppm and 5000 ppm.

[0028] The laminated polyethylene terephthalate film satisfies at least one of the following conditions (1) and (2).

[0029] (1) The average surface roughness (SRa) of the three-dimensional center plane of the aforementioned surface is above 1 nm and below 7.5 nm.

[0030] (2) The maximum peak height (SRp) of the aforementioned surface is below 220 nm.

[0031] [Item 2]

[0032] A laminated polyethylene terephthalate film comprising: a first cover layer containing polyethylene terephthalate resin, an intermediate layer containing polyethylene terephthalate resin, and a second cover layer containing polyester resin.

[0033] The aforementioned first cover layer has a surface for stacking functional layers.

[0034] The aforementioned intermediate layer contains one or more of the following elements: Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0035] The total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the aforementioned laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less.

[0036] The laminated polyethylene terephthalate film satisfies at least one of the following conditions (1) and (2).

[0037] (1) The average surface roughness (SRa) of the three-dimensional center plane of the aforementioned surface is above 1 nm and below 7.5 nm.

[0038] (2) The maximum peak height (SRp) of the aforementioned surface is below 220 nm.

[0039] Here, in items 1 and 2, "the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag and Au" refers to the total amount of these elements in the laminated polyethylene terephthalate film.

[0040] [Item 3]

[0041] The laminated polyethylene terephthalate film according to item 1 or 2, wherein the aforementioned first covering layer is a substantially particle-free layer, and the thickness of the aforementioned first covering layer is 7.0 μm or more and 20.0 μm or less.

[0042] [Item 4]

[0043] The laminated polyethylene terephthalate film according to any one of items 1 to 3 has a melt resistivity value (ρi (10) at 275°C. 8 The Ω·cm is less than 1.00.

[0044] [Item 5]

[0045] The laminated polyethylene terephthalate film according to any one of claims 1 to 4, wherein the aforementioned intermediate layer comprises one or more elements selected from Ti, Ni, Cu, Pt, Pd, Ag, and Au.

[0046] The total amount of Ti, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the aforementioned intermediate layer or the total mass of the aforementioned laminated polyethylene terephthalate film is 10 ppm or more.

[0047] [Item 6]

[0048] The laminated polyethylene terephthalate film according to any one of items 1 to 5, wherein the content of Si element relative to the total mass of the aforementioned intermediate layer or the total mass of the aforementioned laminated polyethylene terephthalate film is 2300 ppm or less.

[0049] [Item 7]

[0050] The laminated polyethylene terephthalate film according to any one of items 1 to 6, wherein the content of Ba element relative to the total mass of the aforementioned intermediate layer or the total mass of the aforementioned laminated polyethylene terephthalate film is 2300 ppm or less.

[0051] [Item 8]

[0052] The laminated polyethylene terephthalate film according to any one of claims 1 to 7, wherein the aforementioned intermediate layer comprises 5% by mass and 100% by mass of a resin obtained by material reuse and / or chemical reuse of the film with the functional layer.

[0053] [Item 9]

[0054] The laminated polyethylene terephthalate film according to any one of items 1 to 8, wherein the intrinsic viscosity (IV) of the aforementioned intermediate layer or the intrinsic viscosity (IV) of the aforementioned laminated polyethylene terephthalate film is 0.400 dl / g or more and 0.700 dl / g or less.

[0055] [Item 10]

[0056] The laminated polyethylene terephthalate film according to any one of items 1 to 9, wherein the aforementioned second covering layer comprises lubricant particles.

[0057] [Item 11]

[0058] A release film comprising:

[0059] The laminated polyethylene terephthalate film according to any one of items 1 to 10; and

[0060] The aforementioned functional layer is disposed on the aforementioned surface of the aforementioned first covering layer of the aforementioned polyethylene terephthalate film.

[0061] The aforementioned functional layer is a release layer.

[0062] [Item 12]

[0063] A method for manufacturing the laminated polyethylene terephthalate film according to any one of items 1 to 10, comprising the following steps:

[0064] (Step 1) Crushing step, which includes: crushing a polyethylene terephthalate film with a functional layer to form a crushed product.

[0065] (Step 2) Fragmentation step, which includes: fragmenting the aforementioned pulverized product to form reusable fragments.

[0066] (Step 3) A preparation step, wherein at least the aforementioned recycled fragments and polyethylene terephthalate fragments different from the aforementioned recycled fragments are prepared such that the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the aforementioned intermediate layer or the total mass of the aforementioned laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less; and

[0067] (Step 4) The reuse film forming step involves melting and extruding the aforementioned reused fragments and the aforementioned polyethylene terephthalate fragments to form a polyethylene terephthalate film as an intermediate layer.

[0068] The present invention is also preferably carried out in the following manner.

[0069] [Item 13]

[0070] The method for manufacturing a laminated polyethylene terephthalate film, a release film, or a laminated polyethylene terephthalate film according to any one of the preceding claims, wherein the polyester resin of the second cover layer is a polyethylene terephthalate resin.

[0071] [Item 14]

[0072] The method for manufacturing a laminated polyethylene terephthalate film, a release film, or a laminated polyethylene terephthalate film according to any one of the preceding claims, wherein the aforementioned intermediate layer comprises Si element.

[0073] [Item 15]

[0074] The method for manufacturing a laminated polyethylene terephthalate film, a release film, or a laminated polyethylene terephthalate film according to any one of the preceding claims, wherein the aforementioned intermediate layer comprises Ti or Ba elements.

[0075] [Item 16]

[0076] The method for manufacturing a laminated polyethylene terephthalate film, a release film, or a laminated polyethylene terephthalate film according to any one of the preceding claims, wherein the aforementioned intermediate layer comprises one or more elements selected from Ni, Cu, Pt, Pd, Ag, and Au, that is, it comprises at least one element selected from the group consisting of Ni, Cu, Pt, Pd, Ag, and Au.

[0077] [Item 17]

[0078] The method for manufacturing a laminated polyethylene terephthalate film, a release film or a laminated polyethylene terephthalate film according to any one of the preceding items satisfies both of the preceding conditions (1) and (2).

[0079] [Item 18]

[0080] A method for manufacturing a laminated polyethylene terephthalate film, a release film, or a laminated polyethylene terephthalate film according to any one of the preceding claims, wherein the first cover layer is free of lubricant particles and / or the intermediate layer contains lubricant particles.

[0081] The effects of the invention

[0082] This invention provides a laminated polyethylene terephthalate film capable of suppressing the transfer of surface shapes to processed articles, a method for manufacturing the same, and a release film. This invention provides a laminated polyethylene terephthalate film capable of suppressing the transfer of surface shapes to processed articles even when using recycled resins containing one or more elements selected from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. Detailed Implementation

[0083] The present invention will now be described in detail.

[0084] The laminated polyethylene terephthalate film (hereinafter sometimes simply referred to as "the laminated polyethylene terephthalate film of the present invention") according to embodiments of the present invention comprises: a first cover layer comprising polyethylene terephthalate resin (hereinafter sometimes referred to as "first cover layer A"), an intermediate layer comprising polyethylene terephthalate resin (hereinafter sometimes referred to as "intermediate layer C"), and a second cover layer comprising polyester resin (hereinafter sometimes referred to as "second cover layer B"). The first cover layer has a surface for laminating functional layers. The intermediate layer comprises one or more elements selected from 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 0.1 ppm or more and 5000 ppm or less relative to the total mass of the intermediate layer or the total mass of the laminated polyethylene terephthalate film.

[0085] The laminated polyethylene terephthalate film satisfies at least one of the following conditions (1) and (2). Here, the laminated polyethylene terephthalate film preferably satisfies both of the following conditions (1) and (2).

[0086] (1) The average surface roughness (SRa) of the three-dimensional center plane of the aforementioned surface is above 1 nm and below 7.5 nm.

[0087] (2) The maximum peak height (SRp) of the aforementioned surface is below 220 nm.

[0088] The intermediate layer of the laminated polyethylene terephthalate film contains one or more elements selected from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, and can therefore be manufactured using recycled resins. Thus, this invention helps to reduce the environmental burden. This will be explained below.

[0089] When using a resin obtained by reusing a silicone-based release film (i.e., a film with a silicone-based release layer) to form the intermediate layer of a laminated polyethylene terephthalate (PET) film, the PET film sometimes contains Si elements derived from the silicone-based release layer. Furthermore, when using a resin obtained by reusing a release film used to manufacture a multilayer ceramic capacitor containing barium titanate to form the intermediate layer of a PET film, the PET film sometimes contains Ti and Ba elements derived from barium titanate remaining in the release film. Similarly, when using a resin obtained by reusing a release film used to manufacture a multilayer ceramic capacitor to form the intermediate layer of a PET film, the PET film sometimes contains electrode components of the multilayer ceramic capacitor remaining in the release film. This can be attributed to the following: During the manufacturing of multilayer ceramic capacitors, electrodes are sometimes printed on the ceramic green sheet formed on the release film before winding. However, this winding process causes the electrode components to adhere to the release film. The electrode components include one or more of the elements Ni, Cu, Pt, Pd, Ag, and Au.

[0090] In the case of using recycled resin to make the intermediate layer of a laminated polyethylene terephthalate film, the laminated polyethylene terephthalate film sometimes contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0091] The laminated polyethylene terephthalate film of the present invention allows for the inclusion of these elements to a certain extent. Therefore, the laminated polyethylene terephthalate film of the present invention allows for the use of recycled resins containing these elements.

[0092] Therefore, the laminated polyethylene terephthalate film of the present invention can help reduce the environmental burden. It should be noted that the laminated polyethylene terephthalate film of the present invention is preferably manufactured using recycled resin, but it can also be manufactured without using recycled resin.

[0093] Furthermore, the upper limit for the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements is 5000 ppm. Therefore, the reusable resin that can be used to manufacture laminated polyethylene terephthalate films can contain these elements to some extent. In other words, the reusable resin that can be used in the manufacture of laminated polyethylene terephthalate films is allowed to contain these elements to some extent. Therefore, the recycling yield can be improved (see Patent Document 1), specifically, the recycling yield of the reusable resin that can be used in the manufacture of laminated polyethylene terephthalate films can be improved.

[0094] Furthermore, since the average surface roughness (SRa) of the three-dimensional center plane of the first cover layer A is 7.5 nm or less or the maximum peak height (SRp) is 220 nm or less, excessive unevenness on the surface of processed articles (hereinafter sometimes referred to as "molded articles") manufactured using laminated polyethylene terephthalate films can be avoided. For example, when manufacturing ceramic green sheets using a release film comprising laminated polyethylene terephthalate films and a release layer, excessive unevenness on the surface of the ceramic green sheet can be avoided. That is, the transfer of surface shape to the ceramic green sheet can be suppressed.

[0095] In one embodiment, the intermediate layer of the laminated polyethylene terephthalate film of the present invention may contain 5% by mass and 100% by mass of a resin obtained by reusing the film with the functional layer. Here, "film with functional layer" includes a substrate film and a functional layer. It should be noted that when the functional layer is a release layer, the film with the functional layer is sometimes referred to as a "release film".

[0096] It should be noted that in this specification, material reuse and / or chemical reuse are sometimes abbreviated as reuse.

[0097] The following mainly describes the composition of laminated polyethylene terephthalate films for demolding purposes (typically as substrate films for demolding films), but laminated polyethylene terephthalate films are not limited to demolding purposes.

[0098] The following mainly describes the composition of laminated polyethylene terephthalate films as biaxially stretched laminated polyethylene terephthalate films, i.e., biaxially oriented laminated polyethylene terephthalate films. However, laminated polyethylene terephthalate films are not limited to biaxially oriented laminated polyethylene terephthalate films.

[0099] The following descriptions of elemental contents (e.g., the total amount and content of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au) are primarily based on the total mass of the interlayer or the total mass of the laminated polyethylene terephthalate film. The elemental contents relative to the total mass of the interlayer and the total mass of the laminated polyethylene terephthalate film can be within suitable ranges as described below.

[0100] The following description focuses primarily on the composition of a second capping layer in a laminated polyethylene terephthalate film comprising polyethylene terephthalate resin, but is not limited to such a composition. The resin used as the second capping layer may be polyethylene terephthalate, polyethylene naphthalate, polyethylene butylene terephthalate, polyethylene cyclohexanediol terephthalate, etc., without particular limitation. Among these, polyethylene terephthalate, i.e., polyethylene terephthalate resin, is preferred.

[0101] It should be noted that the resins of each layer of the laminated polyethylene terephthalate film can be individual materials or a mixed system such as a polymer alloy.

[0102] In one embodiment, the laminated polyethylene terephthalate film of the present invention comprises a resin obtained by reusing a film with a functional layer. The film with the functional layer can be a used film with a functional layer. The aforementioned film with the functional layer can be a release film, such as a used release film.

[0103] Used release film refers to, for example, a release film formed or laminated on a release layer to remove the demolded material from the release layer.

[0104] In addition, used release films may also include: release films that have not been used after manufacturing and have been stored for a long time; release films that have not been used due to reasons such as not meeting required characteristics; and release films whose cut ends cannot achieve their original purpose.

[0105] In one approach, the functionally layered film to be reused, i.e., the functionally layered film that becomes the raw material for the reused resin, is a release film used in the molding of a resin sheet containing an inorganic compound. Examples of inorganic compounds include metal particles, metal oxides, minerals, etc., such as calcium carbonate, silica particles, aluminum particles, barium titanate particles, etc.

[0106] Examples of resins contained in resin sheets include polyvinyl acetal resin and poly(meth)acrylate resin.

[0107] For example, films with functional layers are used in the manufacture of resin sheets requiring high smoothness, such as semiconductor components, ceramic green sheets, and optical films. By reusing the laminated films used for this purpose, various physical properties such as surface roughness can be more effectively exhibited. In addition, in order to maintain smoothness while exhibiting rollability, films with functional layers used for this purpose (e.g., release films) preferably contain particles.

[0108] For example, as described below, the functional layer may include silicone-based, cyclic olefin-based, non-cyclic olefin-based, fluorinated, alkyd-based, acrylic-based, melamine-based, epoxy-based, and other resins.

[0109] A reusable film with a functional layer is a film having a functional layer on at least one side of a substrate film containing a thermoplastic resin. The substrate film is preferably a polyester film, and can be, for example, a laminated polyethylene terephthalate film according to the present invention.

[0110] Therefore, the laminated polyethylene terephthalate film or release film of the present invention can be recycled multiple times, thus making it suitable for the efficient use of resources required by a circular society.

[0111] As long as it does not depart from the scope of the invention, components other than polyester can be reused.

[0112] There are no particular limitations on raw materials, etc., as long as they are within the scope of this invention.

[0113] Resin obtained by reusing a film with a functional layer directly laminated on a substrate film is particularly preferred. By using a film with a functional layer directly laminated on a substrate film, a film with a functional layer containing fewer impurities can be reused, thereby further reducing the surface roughness of the laminated polyethylene terephthalate film and also reducing haze. Polyethylene terephthalate can be listed as a material for the substrate film of the reusable film with a functional layer. Examples of polyethylene terephthalate include homopolymer polyethylene terephthalate and copolymer polyethylene terephthalate.

[0114] The laminated polyethylene terephthalate film of the present invention preferably contains particles. For example, it may contain one or more types of inorganic or organic particles. The particles can function as a lubricant.

[0115] The particles can be inorganic particles such as titanium dioxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, lithium montmorillonite, zirconium oxide, tungsten oxide, lithium fluoride, and calcium fluoride; or organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and organosilicon-based particles. They can contain two or more types of particles. It should be noted that, as inorganic particles, alumina-silica composite oxide particles and hydroxyapatite particles can also be listed. As organic particles, especially heat-resistant organic particles, cross-linked polyacrylic acid particles, cross-linked polystyrene particles, and benzoguanamine-based particles can also be listed.

[0116] From the viewpoints of transparency and cost, silica particles and / or calcium carbonate particles are more preferred as granules. Porous colloidal silica particles are preferred as silica particles. When using calcium carbonate particles, from the viewpoint of preventing lubricant particles from detaching, lightweight calcium carbonate with a surface treatment using a polyacrylic acid-based polymer is preferred.

[0117] The particle content relative to the total mass of the laminated polyethylene terephthalate film is preferably 100 to 10,000 ppm, more preferably 300 to 8,000 ppm. It is also preferably 500 ppm or more. At 100 ppm or more, workability is good, and therefore preferred. At 10,000 ppm or less, excessive unevenness on the surface of the processed product (for example, a ceramic green sheet) can be further avoided.

[0118] In one embodiment, the raw material for the laminated polyethylene terephthalate film of the present invention can be a resin composition obtained by reusing at least a substrate film of a film with a functional layer, such as a polyester resin composition.

[0119] The average particle size of the particles contained in the polyester resin composition is preferably 0.2 μm or more and 5.0 μm or less, more preferably 0.4 μm or more and 5.0 μm or less. When the particle size is 0.2 μm or more, air can be uniformly dispersed when the film is wound into a roll, regardless of whether it is in the production or use of the film, resulting in a good winding shape and good planarity, making it suitable for the manufacture of ultra-thin ceramic green sheets, and therefore preferred (hereinafter referred to as good operability). When the particle size is 5.0 μm or less, the surface unevenness is reduced, further preventing excessive unevenness from forming on the surface of the processed product (e.g., a ceramic green sheet). The average particle size can 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.

[0120] It should be noted that the average particle size can be determined using the method described in the examples. The shape of the particles is not particularly limited as long as it satisfies the purpose of this invention; spherical particles or irregularly shaped non-spherical particles can be used. The particle size of irregularly shaped particles can be calculated in the form of the equivalent diameter of a circle. The equivalent diameter of a circle is obtained by dividing the observed area of ​​the particle by pi (π), calculating the square root, and multiplying by 2.

[0121] The second capping layer B preferably comprises 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. Although it may have been described, the lubricant particles are preferably at least one type of particles selected, for example, from calcium carbonate particles (CaCO3) or silica particles (SiO2).

[0122] From the viewpoint of film slippage and ease of air expulsion, the content of lubricant particles in the second coating layer B is preferably 100 ppm or more and 10,000 ppm or less relative to the total mass of the second coating layer, and more preferably 300 ppm or more and 8,000 ppm or less. A content of 100 ppm or more provides good operability and is therefore preferred. A content of 10,000 ppm or less further avoids excessive unevenness on the surface of the processed product (for example, a ceramic green sheet) caused by surface bulging of the second coating layer.

[0123] Here, the CaCO3 content of calcium carbonate particles can be calculated, for example, by measuring the content of Ca element.

[0124] The laminated polyethylene terephthalate film of the present invention can be a laminated polyethylene terephthalate film that has undergone biaxial stretching.

[0125] 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, more preferably 0.500 dl / g or more and 0.700 dl / g or less, and for example, further preferably 0.510 dl / g or more and 0.650 dl / g or 0.510 dl / g or more and 0.620 dl / g or less. Particularly preferred is 0.510 dl / g or more and 0.580 dl / g or less. It should be noted that the description of the suitable range of intrinsic viscosity of the intermediate layer C is redundant with the corresponding description of the laminated polyethylene terephthalate film, and therefore is omitted.

[0126] When the intrinsic viscosity is 0.500 dl / g or higher, it is less prone to breakage during the stretching process, and is therefore preferred. In addition, biaxial stretching can be performed without impairing film-forming properties.

[0127] Furthermore, at concentrations below 0.700 dl / g, the material exhibits good cutability when cut to the specified product width, preventing dimensional defects, and is therefore preferred. Additionally, it can suppress filter pressure without hindering operability. The raw material is preferably thoroughly vacuum-dried.

[0128] In the case of the laminated polyethylene terephthalate film of the present invention, which is obtained by thinning recycled fragments, it is also desirable to exhibit the above-mentioned characteristic viscosity.

[0129] In one embodiment, the resin comprises 5% by mass and 100% by mass of a resin obtained by reusing a film with a functional layer containing one or more types of inorganic or organic particles. The intrinsic viscosity (IV) of the laminated polyethylene terephthalate film of the present invention is preferably 0.50 dl / g or more and 0.70 dl / g or less, more preferably 0.51 dl / g or more and 0.58 dl / g or less.

[0130] The thickness of the laminated polyethylene terephthalate film is preferably 12 to 100 μm, more preferably 12 to 85 μm, and even more preferably 15 μm to 80 μm. If the film thickness is 12 μm or more, there is no concern about deformation due to heat during film production or when used as a process film, which is therefore preferable. On the other hand, if the thickness of the laminated polyethylene terephthalate film is 100 μm or less, the amount of waste film after use will not increase drastically, which is preferable in terms of reducing environmental burden. Furthermore, less material is used per unit area of ​​the release film, which is also preferable from an economic point of view.

[0131] In one embodiment, the thickness ratio of the first cover layer A is 30% or more and 50% or less of the total thickness of the layers. That is, the thickness of the first cover layer A is preferably 30% or more and 50% or less of the thickness of the laminated polyethylene terephthalate film, which is 100% of the total thickness.

[0132] The laminated polyethylene terephthalate film of this invention has a first cover layer A, an intermediate layer C, and a second cover layer B. The intermediate layer C can be disposed between the first cover layer A and the second cover layer B. The intermediate layer C can have multiple laminated structures.

[0133] When the intermediate layer C contains one or more elements selected from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au, at least one of the first capping layer A and the second capping layer B may also contain one or more elements selected from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. All layers may contain one or more elements selected from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0134] In one approach, the layered structure in the thickness direction can be exemplified by a stacked structure of A / C / B, etc.

[0135] In one embodiment, the thickness of the intermediate layer C can be more than 30% and less than 50% of the thickness of the laminated polyethylene terephthalate film, which is 100% of the total thickness.

[0136] Next, the thickness of the first capping layer A is preferably 7.0 μm or more and 20.0 μm or less. Here, the length of the longest side of the particles from the electrode composition, such as Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au particles, is mostly 0.1 μm or more and 5.0 μm. The lower limit of the thickness of the first capping layer A is more preferably 8.6 μm, and even more preferably 9.0 μm. The upper limit of the thickness of the first capping layer A is more preferably 17.0 μm, and even more preferably 15.0 μm.

[0137] When the thickness of the first cover layer A is 7.0 μm or more, it is possible to prevent these particles on the surface of the intermediate layer C from penetrating the first cover layer A and being exposed from the surface of the first cover layer A, and it is possible to significantly suppress the bulging of the surface of the first cover layer A due to these particles on the surface of the intermediate layer C.

[0138] On the other hand, if the thickness of the first capping layer A is 0.5 μm or more, the first capping layer A can prevent the particles contained in the intermediate layer C from falling off. In view of this, the thickness of the first capping layer A is also preferably 7.0 μm or more.

[0139] The first capping layer A preferably contains substantially no particles with a particle size of 1.0 μm or more, such as inorganic particles with a particle size of 1.0 μm or more. More preferably, the first capping layer A contains no particles with an average particle size of 1.0 μm or more.

[0140] In this method, the first capping layer A may contain particles with a diameter of less than 1.0 μm and greater than 1 nm. By making the first capping layer A substantially free of particles with a diameter of 1.0 μm or greater, such as inorganic particles, it is possible to reduce the possibility of defects occurring when the particle shape in the laminated polyethylene terephthalate film is transferred to the resin sheet (for example, a ceramic green sheet).

[0141] In one approach, by ensuring that the first covering layer A also does not contain particles with a diameter less than 1.0 μm, it is possible to more effectively suppress the occurrence of defects caused by the transfer of particle shape from the laminated polyethylene terephthalate film to the resin sheet.

[0142] In other words, preferably, the first capping layer A not only substantially contains no particles with a diameter of 1.0 μm or larger, but also substantially contains no particles with a diameter of less than 1.0 μm but greater than 1 nm. More preferably, the first capping layer A contains no particles with a diameter of 1.0 μm or larger, nor particles with a diameter of less than 1.0 μm but greater than 1 nm.

[0143] In this invention, "substantially free of particles" means, for example, in the case of inorganic particles smaller than 1.0 μm, that the content of inorganic elements is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit when quantifying inorganic elements. This is because, even without actively adding particles to the film, sometimes contaminants from foreign matter, raw material resins, or dirt adhering to the production line and / or equipment in the film manufacturing process can be shed and mixed into the film. Furthermore, "substantially free of particles with a diameter of 1.0 μm or larger" means that particles with a diameter of 1.0 μm or larger are not actively present. It should be noted that inorganic elements can be quantified by, for example, fluorescence X-ray analysis or ICP emission spectroscopy. It should be noted that ICP refers to inductively coupled plasma.

[0144] In one embodiment, the first coating layer A preferably does not contain particles such as lubricants and does not use recycled materials. This allows for a more effective reduction in surface roughness.

[0145] The surface of the first capping layer A is the surface of the stacked functional layers. The average surface roughness (SRa) of the three-dimensional center plane of this surface is preferably 1 nm or more and 7.5 nm or less, more preferably 1 nm or more and 7 nm or less. Furthermore, the maximum peak height (SRp) of this surface is preferably 220 nm or less, more preferably 200 nm or less. From the viewpoint of manufacturing cost, the maximum peak height (SRp) is preferably 5 nm or more, more preferably 10 nm or more.

[0146] By having such a three-dimensional central plane average surface roughness and maximum peak height, the present invention is able to suppress surface unevenness and can suppress the transfer of unevenness to the processed product.

[0147] The average surface roughness (SRa) of the first cover layer A is preferably 1.5 nm or more and 6.5 nm or less, for example, 2.0 nm or more and 6.0 nm or less. By keeping the average surface roughness (SRa) of the first cover layer A within the above range, high smoothness can also be achieved for functional layers, such as release layers, that are laminated on the first cover layer A.

[0148] For example, by controlling the amounts of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag and Au elements present in the intermediate layer C, the average surface roughness (SRa) and maximum peak height (SRp) of the three-dimensional center surface of the first capping layer A can be set within the range of the present invention.

[0149] On the other hand, the average surface roughness (SRa) of the three-dimensional center plane of the second capping layer B can be 20 nm or more and 40 nm or less. Additionally, the second capping layer B can also exhibit a maximum peak height (SRp) within the aforementioned range. That is, the maximum peak height (SRp) of the second capping layer B can, for example, be 220 nm or less. In one embodiment, for both the first capping layer A and the second capping layer B, at least one of the average surface roughness (SRa) of the three-dimensional center plane and the maximum peak height (SRp) exhibits a different numerical range. Thus, the average surface roughness (SRa) of the three-dimensional center plane of the first capping layer A can be different from that of the second capping layer B. The maximum peak height (SRp) of the first capping layer A can also be different from that of the second capping layer B.

[0150] When the SRa of the first capping layer A is 1 nm or more, air can be uniformly dispersed when the film is rolled into a roll, regardless of whether it is in the production or use of the film, resulting in a good winding shape and good planarity. Therefore, it is suitable for the manufacture of ultrathin ceramic green sheets. When the SRa of the first capping layer A is 7.5 nm or less, surface unevenness can be suppressed, preventing the transfer of unevenness to the molded product.

[0151] The maximum peak height (SRp) of the first capping layer A is preferably 220 nm or less. In one embodiment, the maximum peak height (SRp) of the first capping layer A is more preferably 200 nm or less, and even more preferably 180 nm or less.

[0152] By reducing the maximum peak height (SRp) to below 220 nm, the surface roughness is reduced, which can suppress its transfer to the processed product.

[0153] The intermediate layer C is a layer in which the first cover layer A is stacked on one side and the second cover layer B is stacked on the opposite side.

[0154] The intermediate layer C contains one or more elements selected from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. Additionally, particles can be added appropriately to control the surface shape. In other words, the intermediate layer C may contain added particles.

[0155] The laminated polyethylene terephthalate film can be manufactured, for example, using raw materials obtained from the recycling of films with functional layers. For instance, the intermediate layer C can be manufactured using raw materials obtained from the recycling of films with functional layers. The intermediate layer C may contain one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. The total amount of these elements relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film can be 0.1 ppm or more.

[0156] The laminated polyethylene terephthalate film preferably contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag and Au, and the total amount of these elements relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less.

[0157] By keeping the total content of these elements within the aforementioned range, the operability of, for example, laminated polyethylene terephthalate films becomes good, thereby suppressing unevenness on the film surface and preventing the unevenness from being transferred to the processed product.

[0158] In this context, conventional recycled films tend to actively remove elements such as Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. However, in this invention, by maintaining a predetermined total amount of these elements, the workability of the laminated polyethylene terephthalate film can be well preserved. Furthermore, surface irregularities on the film can be suppressed, further preventing the transfer of these irregularities to the molded product. In one embodiment, surface irregularities on the film can be suppressed at a unit size of several nm to tens of nm. Therefore, even when used for molding extremely thin ceramic green sheets, the release film can be given good processability and peelability.

[0159] Furthermore, the mechanical properties of the laminated polyethylene terephthalate film of the present invention, such as tensile strength and elastic modulus, can also exhibit values ​​that are the same as or higher than those of films formed from unused raw materials that do not contain recycled resin.

[0160] In this way, by setting the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag and Au to a specified level, the physical properties of laminated polyethylene terephthalate films can be improved and they exhibit high reusability.

[0161] The total amount of these elements relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film can, for example, be 0.5 ppm or more, 1.0 ppm or more, or 10 ppm or more. The total amount of these elements can, for example, be less than 3000 ppm or less than 1000 ppm.

[0162] When the first capping layer A does not substantially contain particles containing one or more elements from Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag and Au, the first capping layer A not only has high surface smoothness, but also exhibits high adhesion to the functional layer.

[0163] The total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements in the intermediate layer C 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 the total amount of these elements in the laminated polyethylene terephthalate film.

[0164] In one embodiment, the Si content in the intermediate layer C or the laminated polyethylene terephthalate film is preferably 0.1 ppm or more and 2300 ppm or less. The Si content can be, for example, 2000 ppm or less, 1500 ppm or less, 1000 ppm or less, or 500 ppm or less. The Si content can be 0.3 ppm or more. By keeping the Si content within the above range, the operability of the laminated polyethylene terephthalate film, for example, becomes better, and further, surface irregularities of the film can be suppressed, further preventing the transfer of irregularities to the molded article. Additionally, heat resistance is also improved.

[0165] It should be noted that in previous technologies, when reusing materials of films with functional layers, specifically release films, it was necessary to almost completely remove the organosilicon components present on the surface of the substrate film.

[0166] The content of Ba element in the intermediate layer C or the laminated polyethylene terephthalate film is preferably 0.1 ppm or more and 2300 ppm or less, for example, it can be 1700 ppm or less, or 1000 ppm or less.

[0167] The suitable contents of Ti, Ni, Cu, Pt, Pd, Ag, and Au elements in the intermediate layer C or the laminated polyethylene terephthalate film are the same as the suitable contents of Ba element. That is, each content is preferably 0.1 ppm or more and 2300 ppm or less, for example, 1700 ppm or less, or 1000 ppm or less. In another embodiment, the upper limit can be 500 ppm or less.

[0168] In previous reused films, the residue of ceramic green sheet components, release layer components, electrode components, and substrate film were completely separated, and only high-purity polyester resin was used.

[0169] On the other hand, in this invention, the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements must be within the scope of this invention. Residues from the ceramic green sheet composition, the release layer composition, and the substrate film can be recycled and utilized without departing from the composition of this invention. Therefore, in this invention, for example, compared to conventional methods, the material recycling process for the resin obtained by reusing the film with the functional layer, specifically the release film, can be simplified and shortened, enabling more efficient promotion of waste reduction through recycling.

[0170] The intermediate layer C preferably contains one or more of the elements Ti, Ni, Cu, Pt, Pd, Ag, and Au. This reduces the melt resistivity of the laminated polyethylene terephthalate film at 275°C, thus improving electrostatic adhesion. The total amount of Ti, Ni, Cu, Pt, Pd, Ag, and Au relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film is preferably 10 ppm or more, more preferably 50 ppm or more, and even more preferably 100 ppm or more. This total amount can be less than 5000 ppm, less than 2000 ppm, or less than 200 ppm.

[0171] The intermediate layer C preferably contains one or more of the elements Ni, Cu, Pt, Pd, Ag, and Au. This reduces the melt resistivity of the laminated polyethylene terephthalate film at 275°C, thus improving electrostatic adhesion. The total amount of Ni, Cu, Pt, Pd, Ag, and Au relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film can be 1 ppm or more, 5 ppm or more, 10 ppm or more, or 20 ppm or more. This total amount can be less than 200 ppm, less than 150 ppm, less than 100 ppm, or less than 80 ppm.

[0172] The intermediate layer C preferably contains one or more of the elements Ni, Cu, Pt, Pd, Ag, and Au, as well as Ti. This further reduces the melt resistivity of the laminated polyethylene terephthalate film at 275°C, thus further improving electrostatic adhesion.

[0173] The intermediate layer C preferably contains one or more of the following elements: Ni, Cu, Pt, Pd, Ag, and Au; Ti; Ba; and Si.

[0174] In one embodiment, the melt resistivity (ρi(10)) of the laminated polyethylene terephthalate film of the present invention at 275°C is... 8 The Ω·cm value 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 has excellent film-forming properties and can achieve a high yield.

[0175] In one embodiment, the laminated polyethylene terephthalate film of the present invention contains, within 100% by weight, 5% by weight and less than 100% by weight of a recycled resin (also referred to as recycled raw material). For example, it contains 8% by weight and less than 47% by weight, or, for example, 10% by weight and less than 45% by weight.

[0176] By containing more than 5% by mass and less than 100% by mass, it can reduce the amount of raw materials derived from petroleum, making it an environmentally friendly film.

[0177] As a raw material for material recycling, resin obtained by recycling films with functional layers, specifically release films, can be used. Alternatively, resin obtained by recycling used, predetermined-to-be-discarded release films can also be used.

[0178] For example, when the first cover layer A has a two-layer structure, the recycled material contained in the first cover layer A can be appropriately blended such that the total of the two layers is 5% by mass or more and 100% by mass or less. Similarly, for example, when the intermediate layer C has a multi-layer structure, the recycled material contained in the intermediate layer C can be appropriately blended such that the total of the layers forming the intermediate layer C is 5% by mass or more and 100% by mass or less.

[0179] In one embodiment, the second capping layer B of the laminated polyethylene terephthalate film contains calcium carbonate particles (CaCO3) or silica particles (SiO2). Among these particles, the longest side has a length of 0.5 μm or more and 5.0 μm or less.

[0180] The functional layer of the film to be reused (i.e., the film with a functional layer that serves as a raw material for the reuse resin) is not particularly limited, and may include resins such as silicone-based, cyclic olefin-based, non-cyclic olefin-based, fluorinated, alkyd, acrylic, melamine-based, and epoxy resins. The functional layer preferably includes silicone-based, acrylic-based, or melamine-based resins. By including these resins in the functional layer, the adhesion between the first cover layer A and the second cover layer B in the laminated polyethylene terephthalate film can be improved. In one embodiment, the adhesion between the intermediate layer C and the first cover layer A and the second cover layer B can be improved, thereby obtaining a laminated polyethylene terephthalate film with high smoothness for demolding. Examples of functional layers include easy-to-adhere layers, antistatic layers, demolding layers, and adhesive layers. A demolding layer is preferred, and a silicone demolding layer is more preferred.

[0181] In particular, when the functional layer is used as a release layer, there are sometimes residues of processed material on the surface of the release layer. Therefore, when manufacturing the laminated polyethylene terephthalate film of the present invention, a removal process including removing the deposits from the film with the functional layer can also be performed (see below for details).

[0182] In addition, a high degree of adhesion between the release layer and the object being released is required. For example, release layers for adhesives, optical films, and ceramic green sheets can be used in the manufacturing processes of the object being released and the devices using them, thus requiring a high degree of adhesion between these processes.

[0183] Additionally, the release layer can be a release layer exposed to high temperatures (e.g., above 60°C) and / or high humidity (e.g., above 70%), or a release layer subjected to high tensile conditions. By including a removal process that removes deposits from a film with a functional layer subjected to these conditions, the purity of the reusable resin can be improved, for example, achieving the required optical properties, mechanical strength, etc.

[0184] Organosilicon compounds refer to compounds that have an organosilicon structure within their molecules. Examples include cured organosilicon, organosilicon grafted resins, and alkyl-modified organosilicon resins.

[0185] As an example of the present invention, a method for manufacturing a laminated polyethylene terephthalate film is provided. The manufacturing method includes the following steps (1), (2), (3), and (4).

[0186] (Step 1) Crushing process, which includes crushing a film with a functional layer to form a crushed product.

[0187] (Step 2) Fragmentation process, which breaks down the pulverized product into reusable fragments.

[0188] (Step 3) A step of preparing at least reusable fragments and polyethylene terephthalate fragments different from the reusable fragments, in such a way that the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less; and

[0189] (Step 4) The reuse film forming process involves melt extruding reused fragments and polyethylene terephthalate fragments to form a polyethylene terephthalate film as an intermediate layer.

[0190] Here, the reuse film forming process can be a process of melt extruding a molding material containing reused fragments and polyethylene terephthalate fragments for forming an intermediate layer to obtain a laminated polyethylene terephthalate film.

[0191] In this invention, by including steps 1 to 4, even without the step of removing the deposits on the surface of the film with the functional layer, it is possible to obtain a laminated polyethylene terephthalate film without impairing its physical properties.

[0192] The method for manufacturing a laminated polyethylene terephthalate film may further include a step of removing deposits from the film with the functional layer (hereinafter sometimes referred to as "step 0"). The method for manufacturing a laminated polyethylene terephthalate film preferably includes step 0.

[0193] The following is a detailed description of an example of a method for manufacturing laminated polyethylene terephthalate films.

[0194] (Process 0: The process of removing deposits from a film with a functional layer)

[0195] A film with a functional layer intended for reuse (i.e., a film with a functional layer that serves as a raw material for a reuse resin) has a functional layer disposed on at least one side of a substrate film. That is, the film with a functional layer comprises a substrate film and a functional layer disposed on at least one side of the substrate film. After using the film with a functional layer, residues sometimes remain on the surface of the film with the functional layer, such as the surface of the functional layer or the surface of the substrate film.

[0196] Furthermore, regarding films with functional layers, used films with functional layers, substandard films with functional layers, and films with functional layers damaged during distribution are typically discarded. It is desirable to remove any adhering substances from such predetermined discarded films (i.e., films with functional layers intended for disposal) as long as the final film properties are not impaired. Alternatively, depending on the condition of the adhering substances, the process of removing them may be omitted.

[0197] There are no particular limitations on the methods for removing deposits from films with functional layers. Examples include: methods that remove deposits by attaching and peeling off adhesive rollers; methods that remove deposits using vacuum suction; methods that remove deposits by shaving with a blade; methods that remove deposits using high-pressure water or high-pressure air; methods that remove deposits by blowing sand or dry ice; methods that immerse the film with functional layers in a cleaning layer and remove deposits by adsorption using microbubbles; methods that remove deposits by floating them using ultrasonic micro-vibrations; and methods that remove deposits by dissolving them using supercritical CO2. Combinations of these methods are also possible. While these methods are not particularly limited, methods that allow for roller-to-roll processing are preferred from an efficiency standpoint.

[0198] In this process, several functional layers can be removed along with the attached material, or the functional layers can remain on the substrate film without being removed.

[0199] (Step 1: The process of crushing the film)

[0200] In step 1, the film with the functional layer is crushed to form a pulverized product.

[0201] Methods for pulverizing films with functional layers include, for example, pulverizing the film itself; and separating the film into functional layer and substrate films and then pulverizing them separately or together. The method of pulverizing the film itself is preferred. It should be noted that in the method of separating the film into functional layer and substrate films and then pulverizing them separately, in order to obtain pulverized material for manufacturing reuse fragments, the pulverized material of the functional layer may be mixed with the pulverized material of the substrate film, or they may not be mixed. If they are not mixed, the pulverized material for manufacturing reuse fragments can be either the pulverized material of the substrate film or the pulverized material of the functional layer. The pulverization of the film with functional layers can be performed using a single-screw pulverizer, a twin-screw pulverizer, a triple-screw pulverizer, a milling machine, or other pulverizers.

[0202] Examples of the forms in which pulverized products can be flaky, powdery, blocky, or strip-shaped. Flaky form is preferred.

[0203] In this way, the pulverization process can be performed without removing the deposits on the surface of the film with the functional layer. Therefore, for example, there may be deposits such as adhesives, ceramic flakes, and impurities on the surface of the functional layer. Alternatively, some of these deposits can be removed before the pulverization process. By removing some of the deposits, the content of elements such as Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au can be easily controlled.

[0204] In other words, the manufacturing method of the embodiments of the present invention does not require the complete removal of adhesives, ceramic green sheets, impurities, and other deposits on the surface of the functional layer, as is the case with conventional recycling techniques. The manufacturing method of the embodiments of the present invention may not require the removal of the functional layer itself; however, a portion of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au can be removed to control their content.

[0205] The manufacturing method of this invention allows the functional layer and substrate film containing such deposits to be directly fed into the pulverizing process. Therefore, compared to conventional recycling technologies, the processes and time required for manufacturing resin granules and forming films can be significantly reduced. Furthermore, the amount of waste can be reduced.

[0206] (Process 2: Process of manufacturing reusable fragments)

[0207] The preferred method for manufacturing reusable fragments is to granulate the pulverized material through melt extrusion. Examples of granulation equipment include single-screw extruders, twin-screw extruders, and multi-screw extruders. Twin-screw or multi-screw extruders, which combine control of mixing strength and inhibition of resin degradation, are preferred. To remove large foreign matter, the pulverized material can be passed through a filter from the time it is molten until extrusion.

[0208] As described above, the intermediate layer C contains one or more of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au. Furthermore, the total amount of these elements relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less. For safety reasons, it will be explained beforehand that the manufacturing method of the embodiments of the present invention does not require the complete removal of the elements Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au.

[0209] Granular form is preferred as the shape of the recycled fragments.

[0210] (Step 3: Preparation of reusable waste and polyethylene terephthalate waste)

[0211] In step 3, preferably, the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the intermediate layer C or the total mass of the laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less, so as to prepare at least the reusable fragments and polyethylene terephthalate fragments.

[0212] The preferred shape for polyethylene terephthalate (PET) fragments is granular.

[0213] Polyethylene terephthalate (PET) fragments include homopolymer PET and copolymer PET. Homopolymer PET is preferred. The description of PET in PET fragments is redundant with the description of PET in films with functional layers for reuse, and therefore is omitted.

[0214] Polyethylene terephthalate (PET) fragments may contain particles. The description of particles in PET fragments is redundant with the description of particles in laminated PET films, and therefore omitted. PET fragments may contain additives. Examples of additives include, for instance, antioxidants, light stabilizers, UV absorbers, and crystallizing agents.

[0215] In step 3, polyethylene terephthalate fragments can be further prepared.

[0216] In step 3, it is preferable to mix at least the recycled fragments with the polyethylene terephthalate (PET) fragments. This yields a mixed fragment comprising both recycled fragments and PET fragments.

[0217] (Process 4: Thin film manufacturing process)

[0218] In step 4, the molding material used to form the intermediate layer C is melt-extruded to obtain a laminated polyethylene terephthalate film. The molding material used to form the intermediate layer C includes recycled fragments and polyethylene terephthalate fragments. In step 4, it is preferable to melt-extrude a mixture of recycled fragments and polyethylene terephthalate fragments as the molding material used to form the intermediate layer C to obtain a laminated polyethylene terephthalate film.

[0219] The film-forming method is not limited. Specifically, recycled waste and polyethylene terephthalate (PET) waste are thoroughly vacuum-dried, mixed, and then fed to an extruder as the molding material for forming the intermediate layer C. The mixture is melt-extruded into sheets at approximately 255–280°C and allowed to cool and solidify, forming an unstretched PET sheet. The unstretched PET sheet is then stretched 3.0–6.0 times its length using rollers heated to 75–140°C to obtain a uniaxially oriented PET film. Next, the ends of the uniaxially oriented PET film are held by a clamp and introduced into a hot air zone heated to 75–140°C. After drying, it is stretched 3.0–6.0 times its width. Finally, it can be heat-set in a zone at 180–260°C for 1–60 seconds. In this heat treatment process, a relaxation treatment of 0 to 10% can be performed in the width or length direction as needed.

[0220] It should be noted that, in order to remove large foreign objects, the recycled fragments can be passed through a filter from the time they are molten until they are extruded. The finer the mesh of the filter, the more small foreign objects it can remove.

[0221] In step 4, a biaxially oriented laminated polyethylene terephthalate film can be obtained by following the steps described above: the molding material used to form the intermediate layer C (i.e., a mixture of recycled fragments and polyethylene terephthalate fragments), the molding material used to form the first cover layer A (e.g., polyethylene terephthalate fragments), and the molding material used to form the second cover layer B (e.g., a mixture of polyethylene terephthalate fragments or recycled fragments and polyethylene terephthalate fragments containing particles) are co-extruded, the unstretched laminated polyethylene terephthalate sheet is biaxially stretched, and heat-set as needed.

[0222] The descriptions of the polyethylene terephthalate (PET) fragments used to form the first cover layer A and the second cover layer B are redundant with the description of the PET fragments used to form the intermediate layer C, and are therefore omitted. It should be noted that the molding material used to form the first cover layer A preferably does not contain recycled fragments.

[0223] The description of the recycled fragments used to form the second cover layer B is redundant with the description of the recycled fragments used to form the intermediate layer C, and therefore is omitted. It should be noted that, for the sake of caution, it is stated in advance that the molding material used to form the second cover layer B may or may not contain recycled fragments.

[0224] In summary, it is possible to obtain a laminated polyethylene terephthalate film containing a resin obtained by reusing a film with a functional layer.

[0225] (Resin sheet)

[0226] In one embodiment, the laminated polyethylene terephthalate film of the present invention can be used as a substrate film in a release film for resin sheet molding.

[0227] There are no particular limitations as long as it is a resin sheet; it can be used in the manufacture of adhesives and optical films. In one embodiment, it is a release film for molding resin sheets containing inorganic compounds. Examples of inorganic compounds include metal particles, metal oxides, minerals, etc., such as calcium carbonate, silica particles, aluminum particles, barium titanate particles, etc.

[0228] Examples of resins include polyvinyl acetal resin and poly(meth)acrylate resin.

[0229] The laminated polyethylene terephthalate film of the present invention is suitable for lamination of release layers with high smoothness. Even when these inorganic compounds are included in the resin sheet, it can suppress the defects that may be caused by inorganic compounds, such as resin sheet breakage and difficulty in peeling the resin sheet from the release layer.

[0230] The resin components used to form resin sheets can be selected appropriately based on their intended use.

[0231] In one embodiment, the resin sheet containing the inorganic compound is a ceramic green sheet. For example, the ceramic green sheet may contain barium titanate as the inorganic compound. In another embodiment, the thickness of the resin sheet is 0.2 μm or more and 1.0 μm or less.

[0232] (Mold release film)

[0233] In one embodiment, the release film of the present invention comprises a laminated polyethylene terephthalate film and a release layer. The release layer is disposed on the surface of a first cover layer A of the laminated polyethylene terephthalate film. That is, the release film comprises a laminated polyethylene terephthalate film and a release layer laminated on the first cover layer A of the laminated polyethylene terephthalate film.

[0234] The description of the release layer of the release film is the same as the description of the release layer of the film with a functional layer (i.e., the film with a functional layer to be reused), and therefore is omitted. Therefore, the description of the release layer of the film with a functional layer described above can also be treated as the description of the release layer of the release film of the present invention. It should be noted that the release layer can be provided on the surface of the cover layer by a so-called online coating method, which involves coating during the film-making process of the laminated polyethylene terephthalate film, or it can be provided on the surface of the cover layer after the laminated polyethylene terephthalate film has been made.

[0235] Example

[0236] The present invention will now be described in more detail using examples, but the invention is not limited to these examples. The characteristic values ​​used in the present invention are evaluated using the methods described below.

[0237] (1) Intrinsic viscosity (IV)

[0238] The film (specifically, laminated polyethylene terephthalate film) or polyester resin (specifically, recycled PET1~8, PET11, MB12) is pulverized and dried, then dissolved in a mixed solvent of phenol / tetrachloroethane = 60 / 40 (mass ratio). After centrifuging the solution to remove inorganic particles, the flow time of a 0.4 (g / dl) solution and the flow time of the solvent alone are measured using an Ubbelohde viscometer at 30°C. Based on their time ratio, the intrinsic viscosity is calculated using the Huggins formula, assuming a Huggins constant of 0.38.

[0239] (2) Si and Ti analysis

[0240] As a pretreatment, approximately 1 g of sample (specifically, laminated polyethylene terephthalate films, recycled PET1-8, PET11, and MB12) was taken and mixed with 15 ml of nitric acid, 3 ml of ultrapure water, and 0.1 ml of hydrofluoric acid. The sample was soluble in the acid using a microwave sample decomposition device (UltraWAVE manufactured by Milestone Co., Ltd.). Then, the elemental content of Si and Ti was determined using an ICP emission spectrometer (SPECTRO BLUE TI manufactured by SPECTRO).

[0241] (3) Analysis of Ba, Ni, Cu, Pd, Ag, Au, Pt

[0242] As a pretreatment, approximately 0.5 g of sample (specifically, laminated polyethylene terephthalate films, recycled PET1-8, PET11, and MB12) was collected. After carbonization / ashing, the residue was dissolved in 1.2 N hydrochloric acid to prepare the sample for determination. Then, the elemental amounts of Ba, Ni, Cu, Pd, Ag, Au, and Pt were determined using an ICP emission spectrometer (SPECTRO BLUE TI).

[0243] (4) Ca analysis

[0244] As a pretreatment, approximately 0.5 g of sample (specifically, laminated polyethylene terephthalate films, recycled PET1-8, PET11, and MB12) was collected. After carbonization / ashing, the residue was dissolved in 1.2N hydrochloric acid to prepare the sample for analysis. Then, the elemental content of Ca was determined using an ICP emission spectrometer (SPECTRO BLUE TI). The CaCO3 content of the calcium carbonate particles was calculated by determining the Ca elemental content.

[0245] (5) Surface roughness (SRa, SRp)

[0246] The surface of the outermost layer (specifically, the first capping layer A) of the laminated polyethylene terephthalate (PET) film was measured using a stylus-type three-dimensional roughness meter (SE-3AK, manufactured by Kosaka Research Institute Co., Ltd.). With a stylus radius of 2 μm and a load of 30 mg, measurements were performed along the length of the PET film, with a cutoff of 0.25 mm, a measurement length of 1 mm, and a stylus feed rate of 0.1 mm / s. The measurement was divided into 500 points at 2 μm intervals, and the height of each point was read using a three-dimensional roughness analyzer (SPA-11). For the width direction of the PET film, the same operation was performed 150 times consecutively at 2 μm intervals, i.e., the operation was performed 0.3 mm across the width direction of the PET film, and the data was read using the analyzer. Then, the center surface average roughness (SRa) and centerline peak height (SRp) were determined using the analyzer.

[0247] (6) Average particle size

[0248] The roughening agent was observed using a scanning electron microscope (Hitachi, S-51O type). The magnification was adjusted appropriately according to the particle size, and the photographs were enlarged and copied. Next, for at least 200 randomly selected particles, the outer periphery of each particle was tracked, and the circumference equivalent diameter of the particles was determined from their tracking images using an image analysis device. The average value of these values ​​was taken as the average particle size.

[0249] (7) Evaluation of MLCC processability

[0250] After forming a silicone-based release layer as a functional layer on a laminated polyethylene terephthalate (PET) film, ceramic green sheets are manufactured, and the defect rate caused by the laminated PET film is evaluated. Specifically, the defect rate is evaluated according to the following steps.

[0251] (Preparation of release film)

[0252] On the surface of the first capping layer A of the laminated polyethylene terephthalate film, a coating thickness (wet weight) of 5 g / m is applied. 2 The coating liquid described below is applied using a reverse gravure printing plate, and then dried at 100°C for 2 seconds 0.5 seconds after coating (hereinafter sometimes referred to as "initial drying"). After continuous heating at 130°C for 7 seconds without interruption from the initial drying (i.e., continuously from the initial drying), the film is rolled up 8 seconds after the end of the heating. Thus, 100 release films are produced in each example.

[0253] (Coating liquid used to make release films)

[0254] The composition of the coating solution used to prepare the release film is as follows. The solid content of the coating solution is 1.0% by mass, the surface tension is 27 mN / m, and the viscosity is 5 mPa·s. It should be noted that this coating solution is used after passing through a filter capable of removing more than 99% of foreign matter larger than 0.5 μm.

[0255] 57.93 parts by weight of methyl ethyl ketone

[0256] 40.00 parts by weight of toluene

[0257] Resin solution R (a 40% by weight solution of acrylic polyol containing long-chain alkyl groups. Preparation method described below) 1.75 parts by weight

[0258] Crosslinking agent (hexamethoxyhydroxymethyl melamine, solid content 100% by weight) 0.25 parts by weight

[0259] Organosilicon-based mold release agent (polyether-modified polydimethylsiloxane, TSF4446, 100% by weight, manufactured by Momentive) 0.05 parts by weight

[0260] Acid catalyst (p-toluenesulfonic acid) 0.02 parts by weight

[0261] (Preparation of resin solution R)

[0262] The stearate (meth)acrylate was mixed in a ratio of 20 mol%, hydroxyethyl (meth)acrylate, and methyl (meth)acrylate in a ratio of 40 mol%. The mixture was then diluted with toluene to a solids content of 40% by mass. 0.5 mol% of azobisisobutyronitrile (AIBN) was added under a nitrogen atmosphere to copolymerize the mixture. This yielded a resin solution R (i.e., an acrylic polyol solution containing long-chain alkyl groups) with a solids content of 40% by mass. The resulting polymer had a weight-average molecular weight of 30,000.

[0263] (The production of ceramic raw slabs)

[0264] After mixing the following materials, disperse them for 60 minutes using a bead mill with 0.5 mm diameter zirconia beads as the dispersion medium. This yields a ceramic slurry.

[0265] 43.75 parts by weight of toluene

[0266] 43.75 parts by weight of ethanol

[0267] Barium titanate (HPBT-1 manufactured by Fuji Titanium Co., Ltd.) 10.86 parts by weight

[0268] Polyvinyl butyral (S-LEC BM-S manufactured by Sekisui Chemicals Co., Ltd.) 1.09 parts by weight

[0269] DOP (dioctyl phthalate) 0.55 parts by weight

[0270] A ceramic slurry was applied to the release layer of the release film using a coater to a thickness of 1.0 μm, resulting in a ceramic green sheet. The slurry was then dried at 90°C for 2 minutes. This process produced a ceramic green sheet on the release film. It should be noted that 100 ceramic green sheets were produced in each example.

[0271] (Judgment of superiority or inferiority)

[0272] After the ceramic green sheet is peeled from the release film, the arithmetic mean roughness Ra and maximum protrusion height Rp of the peeled surface (i.e., the surface of the ceramic green sheet that is in contact with the release film) are measured, and the quality is judged according to the following criteria. It should be noted that Ra and Rp are measured using a scanning white interference microscope "VertscanVS1530" manufactured by Hitachi High-Technologies Corporation.

[0273] Ideally, Ra should be less than 8 nm and Rp should be less than 50 nm.

[0274] Poor Ra is above 8nm or Rp is above 50nm

[0275] (Calculation of defect rate)

[0276] The defect rate for each example can be calculated using the following formula.

[0277] Defect rate (%) = (Number of ceramic green tiles judged to be defective / 100 tiles) × 100

[0278] The defect rates for each case are shown in Table 3 according to the following classification.

[0279] ○ Failure rate below 3%

[0280] △ Defect rate greater than 3% but less than 5%

[0281] × Defect rate greater than 5%

[0282] (8) Molten resistivity

[0283] A pre-stretch sheet of laminated polyethylene terephthalate film was used as the subject. Two electrodes (0.6 mm diameter stainless steel wires) were placed at both ends. A uniform layer of molten polyester composition with a width of 2 cm and a thickness of 0.6 mm was formed by clamping it with two quartz plates with a width of 2 cm. The current (io) was measured when a DC voltage of 120 V was applied at a temperature of 275 °C. Substituting this current into the following formula, the melt resistivity value ρi (10) was calculated. 8 Ω·cm).

[0284] ρi (Ω·cm) = (A / L) × (V / io)

[0285] [A: Electrode area, L: Electrode distance (cm), V: Voltage (V)]

[0286] A (cm) 2 = [Width of molten polyester composition layer] × [Thickness] = 2 (cm) × 0.06 (cm), V = 120 (V). L is a value measured excluding the electrode diameter, which is 1.3 cm. Evaluation is performed according to the following benchmark values.

[0287] Electrostatic adhesion S: molten resistivity value below 0.20.

[0288] Electrostatic adhesion A: Melt resistivity value greater than 0.20 and less than 1.00.

[0289] Electrostatic adhesion B: Melt resistivity value greater than 1.00

[0290] (Preparation of PET1 for reuse)

[0291] Used PET film with a silicone-based release layer on one side and containing 600 ppm of calcium carbonate with a particle size of 0.9 μm was used. This film was placed in a single-screw pulverizer and pulverized through a 4 mm mesh screen at a speed of 1000 kg / h to obtain pulverized film. The pulverized film was then fed into a twin-screw extruder to obtain recycled PET1. The intrinsic viscosity of recycled PET1 was 0.56 dl / g, and the Si concentration was 200 ppm. The evaluation results and various conditions are shown in Table 1.

[0292] (Preparation of reused PET2)

[0293] Prepare a used PET film with a silicone-based release layer on one side and containing 600 ppm of calcium carbonate with a particle size of 0.9 μm. This PET film is used to manufacture ceramic green sheets. The silicone-based release layer was removed from the PET film by sandblasting (this process is not explicitly described, but for safety, it is noted that impurities attached to the silicone-based release layer were also removed). The film after the silicone-based release layer was removed was placed in a single-screw pulverizer and pulverized through a 4 mm mesh screen at a speed of 100 kg / h to obtain pulverized film. The pulverized film was fed into a twin-screw extruder to obtain recycled PET2. The intrinsic viscosity of recycled PET2 was 0.56 dl / g, and the Si concentration was 5 ppm. The evaluation results and various conditions are shown in Table 1.

[0294] (Preparation using PET3, 4, 5, 6, 7, and 8)

[0295] Used PET film with a silicone-based release layer on one side and containing 600 ppm of calcium carbonate with a particle size of 0.9 μm was used. This PET film (i.e., a PET film with a silicone-based release layer) was used to manufacture multilayer ceramic capacitors. In the manufacture of multilayer ceramic capacitors, a ceramic green sheet was formed on the silicone-based release layer of the PET film (i.e., the PET film with a silicone-based release layer), electrodes were printed on the ceramic green sheet, and the film was wound into a roll. In the manufacture of multilayer ceramic capacitors, after the PET film was wound out, the ceramic green sheet was peeled off from the PET film. The film was placed in a single-screw pulverizer and pulverized at a speed of 100 kg / h through a 4 mm mesh screen to obtain pulverized film. The obtained pulverized film was fed into a twin-screw extruder to obtain recycled PET 3, 4, 5, 6, 7, and 8. The evaluation results and various conditions are shown in Table 1.

[0296] It should be noted that the PET films used to prepare recycled PET1~3 (specifically, ET films with an organosilicon release layer) are the same products as before use.

[0297] The PET film used to prepare recycled PET4 (specifically, an ET film with a silicone-based release layer) is the same product as the PET film used to prepare recycled PET5 (specifically, an ET film with a silicone-based release layer) before use.

[0298] The PET film used to prepare recycled PET6 (specifically, ET film with a silicone release layer) is the same product as the PET film used to prepare recycled PET7 (specifically, ET film with a silicone release layer) before use.

[0299] (Preparation of polyethylene terephthalate granules (PET11))

[0300] The esterification reactor was a continuous esterification reactor consisting of a stirring device, a condenser, and a three-stage fully mixing tank with a feed inlet and a product outlet. TPA was set at 2 tons / hr, EG at 2 moles per 1 mole of TPA, and antimony trioxide at 160 ppm of Sb atoms per PET product. This slurry was continuously fed to the first esterification tank of the reactor and reacted at 255°C with an average residence time of 4 hours under normal pressure.

[0301] Next, the reaction product from the first esterification reactor is continuously withdrawn from the system and fed to the second esterification reactor. EG removed by distillation from the first esterification reactor is supplied to the second esterification reactor at a mass ratio of 8% relative to the generated polymer (generated PET). Then, an EG solution containing magnesium acetate at a Mg atom concentration of 65 ppm relative to the generated PET and an EG solution containing TMPA at a P atom concentration of 20 ppm relative to the generated PET are added. The reaction is carried out at 260°C with an average residence time of 1.5 hours under normal pressure. Next, the reaction product from the second esterification reactor is continuously withdrawn from the system and fed to the third esterification reactor. An EG solution containing TMPA at a P atom concentration of 20 ppm relative to the generated PET is further added. The reaction is carried out at 260°C with an average residence time of 0.5 hours under normal pressure. The esterification reaction product generated in the aforementioned third esterification reactor is continuously fed into a three-stage continuous polycondensation reactor for polycondensation, and further filtered using stainless steel sintered filter media (nominal filtration accuracy: removing 90% of 5μm particles). This yields polyethylene terephthalate granules, i.e., PET11, with an intrinsic viscosity of 0.62 dl / g. Evaluation results and various conditions are shown in Table 1.

[0302] (Preparation of polyethylene terephthalate calcium carbonate masterbatch (MB12))

[0303] The above-mentioned PET11 and calcium carbonate particles with an average particle size of 0.9 μm were melt-blended using a twin-screw extruder to produce a masterbatch with a calcium carbonate particle concentration of 20,000 ppm. The evaluation results and various conditions are shown in Table 1.

[0304] (Example 1)

[0305] After drying, the PET sheets were melted at 290°C using a melt extruder. The melted PET was then subjected to two-stage filtration: a filter obtained by sintering 95% of stainless steel fibers with a diameter of 15 μm and removing them, and a filter obtained by sintering 95% of stainless steel particles with a diameter of 15 μm and removing them. Subsequently, the molten PET was combined in a feed block and layered as follows: 75% PET11 and 25% MB12 to form layer B (reverse demolding side layer), PET11 to form layer A (demolding side layer), 60% PET11 and 40% PET1 to form layer C. This was then extruded (cast) into sheets at a speed of 45 m / min and electrostatically bonded / cooled on a casting drum at 30°C using an electrostatic sealing method. The result was an unstretched polyethylene terephthalate sheet with an intrinsic viscosity of 0.56 dl / g. The layer ratio (i.e. thickness ratio) is adjusted to A layer / C layer / B layer = 40% / 40% / 20% based on the ejection volume of each extruder.

[0306] The electrostatic sealing conditions at this time are set as follows: the electrode material is tungsten, a cylindrical (wire) with a diameter of 0.2 mm and a length of 0.5 m, the current is constantly controlled at 5 mA, the electrode tension is 5 kg, and the electrode renewal rate is 5 m / hour.

[0307] Next, the unstretched polyethylene terephthalate sheet was heated with an infrared heater and then stretched 3.5 times longitudinally using the speed difference between the rolls at a roll temperature of 80°C. It was then fed into a tenter frame and stretched 4.2 times transversely at 140°C. Next, it was heat-treated at 210°C in a heat-setting zone. Finally, it underwent a 2.3% relaxation treatment transversely at 170°C to obtain a mill roll (5.0m wide) of laminated polyethylene terephthalate film with a thickness of 25μm.

[0308] The calendered roll was moved to a cutting machine and treated with a de-energizer (manufactured by Kasuga Electric Co., Ltd., high-density de-energizing system) and a wire cleaner (manufactured by Shinsei Co., Ltd., ultrasonic cleaning system). Then, the calendered roll was cut into 1400mm wide pieces and wound onto a core material with resin-impregnated paper, having an inner diameter of 6 inches, a wall thickness of 12mm, a moisture content of 8%, a surface roughness (SRa=4.3nm, SRp=41.4nm), and a flattened compressive strength of 200kg / 100mm. The winding was carried out at a maximum speed of 400m / min using contact rollers with a rubber hardness of 60 degrees, with a contact surface pressure of 200kg / m and a tension of 15MPa. This yielded a biaxially stretched polyethylene terephthalate (PET) film roll. Laminated PET films were cut from the biaxially stretched PET film roll and subjected to various evaluations. The laminated polyethylene terephthalate film is a film consisting of layer A (first capping layer), layer C (intermediate layer), and layer B (second capping layer) stacked sequentially. The evaluation results are shown in Tables 2 and 3.

[0309] It should be noted that the dust level of the atmosphere in the thin film manufacturing process is Class 1000.

[0310] (Examples 2 and 3)

[0311] Compared to Example 1, the raw material formulation of layer C was changed, and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film roll was also changed, resulting in the biaxially stretched PET film roll shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film roll and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0312] (Examples 4, 5, 6, 7, 8, 9, 10, 11)

[0313] Compared to Example 1, the raw material for layer C was changed from recycled PET1 to the raw materials and blending amounts listed in Table 2, and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film roll was also changed, resulting in the biaxially stretched PET film roll shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film roll and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0314] (Example 12)

[0315] Compared to Example 1, the layer ratio (i.e., thickness ratio) was varied as shown in Table 2 to obtain the biaxially stretched polyethylene terephthalate (PET) film rolls as shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film rolls and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0316] (Comparative Example 1)

[0317] Compared to Example 1, the raw materials and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film rolls were changed as shown in Table 2, resulting in the biaxially stretched PET film rolls shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film rolls and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0318] (Comparative Example 2)

[0319] Compared to Example 1, the layer composition was changed to a two-layer A / B structure, and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film roll was also changed, resulting in the biaxially stretched PET film roll shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film roll and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0320] (See Example 3 for reference)

[0321] Compared to Example 1, the layer ratio (i.e., thickness ratio) and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film rolls were varied as shown in Table 2 to obtain the biaxially stretched PET film rolls shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film rolls and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0322] It should be noted that the average surface roughness (SRa) of the three-dimensional center surface of the surface in Reference Example 3 is 1 nm or more and 7.5 nm or less, but the maximum peak height (SRp) of the surface is 220 nm or more. Reference Example 3 is sometimes referred to as Example 13.

[0323] (Comparative Example 4)

[0324] Compared to Example 1, the layer ratio (i.e., thickness ratio) and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film rolls were varied as shown in Table 2 to obtain the biaxially stretched PET film rolls shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film rolls and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0325] (Comparative Example 5)

[0326] Compared to Example 11, the layer ratio (i.e., thickness ratio) and the film thickness of the biaxially stretched polyethylene terephthalate (PET) film rolls were varied as shown in Table 2 to obtain the biaxially stretched PET film rolls shown in Table 2. Laminated PET films were cut from the biaxially stretched PET film rolls and various evaluations were performed. The evaluation results are shown in Tables 2 and 3.

[0327] Ceramic green sheets were manufactured using the biaxially stretched polyethylene terephthalate films described in Examples 1-12, and the defect rate caused by the biaxially stretched polyethylene terephthalate films was evaluated. The defect rate was suppressed to below 3%, and good ceramic green sheets were obtained.

[0328] Furthermore, by using films derived from recycled materials, environmentally friendly products (specifically, biaxially stretched polyethylene terephthalate films and release films) can be manufactured. The laminated polyethylene terephthalate films described in the examples exhibit the same performance as the laminated polyethylene terephthalate films described in Comparative Example 2 (i.e., laminated polyethylene terephthalate films obtained without using recycled PET1-8).

[0329] In Comparative Examples 1, 4, and 5, the average surface roughness (SRa) and maximum peak height (SRp) of the three-dimensional center plane of the first capping layer A are outside the scope of the present invention, and the processability of MLCC (i.e., the formability of ceramic green sheets) is insufficient.

[0330] Comparative Example 2 does not contain Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements, which are outside the scope of this invention. Comparative Example 2 does not use recycled PET1-8, thus not contributing to reducing the environmental burden.

[0331] Furthermore, Examples 5-11 exhibit superior electrostatic adhesion compared to Examples 1-4 and 12. That is, Examples 5-11 demonstrate superior film-forming properties and a high yield compared to Examples 1-4 and 12. Therefore, Examples 5-11 can reduce product costs compared to Examples 1-4 and 12.

[0332] [Table 1]

[0333]

[0334] [Table 2]

[0335]

[0336] It should be noted that the calcium carbonate concentration in Table 2 is the concentration of calcium carbonate in the laminated polyethylene terephthalate film when the mass of layer B (second cover layer) is set to 100% by mass.

[0337] [Table 3]

[0338]

[0339] It should be noted that the concentrations, or in other words, the contents of each element in Table 3 are the contents of each element in the laminated polyethylene terephthalate film when the mass of layer C (intermediate layer) is set to 100% by mass.

[0340] Industrial availability

[0341] The laminated polyethylene terephthalate film of the present invention can suppress the transfer of surface shape to the processed article even when it is made 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 is industrially available.

Claims

1. A laminated polyethylene terephthalate film, comprising: a first covering layer comprising polyethylene terephthalate resin, an intermediate layer comprising polyethylene terephthalate resin, and a second covering layer comprising polyester resin. The first cover layer has a surface for stacking functional layers. The intermediate layer contains one or more of the following 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 elements relative to the total mass of the intermediate layer is more than 0.1 ppm and less than 5000 ppm. The laminated polyethylene terephthalate film satisfies at least one of the following conditions (1) and (2): (1) The average surface roughness (SRa) of the three-dimensional center plane of the surface is greater than 1 nm and less than 7.5 nm; (2) The maximum peak height (SRp) of the surface is below 220 nm.

2. The laminated polyethylene terephthalate film according to claim 1, wherein, The first capping layer is a substantially particle-free layer, and the thickness of the first capping layer is more than 7.0 μm and less than 20.0 μm.

3. The laminated polyethylene terephthalate film according to claim 1, wherein the melt resistivity value at 275°C (ρi(10)) is... 8 The Ω·cm is less than 1.

00.

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

5. The laminated polyethylene terephthalate film according to claim 1, wherein, The Si content relative to the total mass of the intermediate layer is less than 2300 ppm.

6. The laminated polyethylene terephthalate film according to claim 1, wherein, The content of Ba relative to the total mass of the intermediate layer is less than 2300 ppm.

7. The laminated polyethylene terephthalate film according to claim 1, wherein, The intermediate layer comprises 5% by mass and less than 100% by mass of a resin obtained by material reuse and / or chemical reuse of a film with a functional layer.

8. The laminated polyethylene terephthalate film according to claim 1, wherein, The intrinsic viscosity (IV) of the laminated polyethylene terephthalate film is above 0.400 dl / g and below 0.700 dl / g.

9. The laminated polyethylene terephthalate film according to claim 1, wherein, The second coating layer contains lubricant particles.

10. A release film comprising: The laminated polyethylene terephthalate film according to any one of claims 1 to 9; and The functional layer is disposed on the surface of the first covering layer of the laminated polyethylene terephthalate film. The functional layer is a release layer.

11. A method for manufacturing the laminated polyethylene terephthalate film according to any one of claims 1 to 9, comprising the following steps: (Step 1) Crushing process, which includes: A polyethylene terephthalate film with a functional layer is pulverized to form a pulverized product; (Step 2) Fragmentation step, which includes: fragmenting the pulverized product to form reusable fragments; (Step 3) A preparation step, wherein at least the reusable fragments and polyethylene terephthalate fragments different from the reusable fragments are prepared such that the total amount of Si, Ti, Ba, Ni, Cu, Pt, Pd, Ag, and Au elements relative to the total mass of the laminated polyethylene terephthalate film is 0.1 ppm or more and 5000 ppm or less; and (Step 4) The reuse film forming step involves melting and extruding the reused fragments and the polyethylene terephthalate fragments to form a polyethylene terephthalate film as the intermediate layer.

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