Polyester resin molded articles, polyester products, and methods for manufacturing polyester resin molded articles

Abstract

To provide a polyester resin molded article that is suitable for manufacturing environmentally friendly polyester products, possessing high runability, smoothness with minimal foreign matter, and excellent run-through properties. [Solution] A polyester resin molded article made using a polyester resin support obtained by removing the coating film from a polyester resin substrate having a polyester resin support and a coating film containing at least one layer of silicon, wherein the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less based on the weight of the polyester resin molded article.

Description

[Technical Field]

[0001] The present invention relates to a polyester resin molded article, a polyester product, and a method for manufacturing a polyester resin molded article. [Background technology]

[0002] Polyester resin substrates are used in a wide variety of applications due to their excellent mechanical, physical, and chemical properties. Many of these polyester resin substrates have coatings with various functions laminated on one or both sides of their surface. For example, release films made by using a polyester film as a polyester resin support and providing a release layer mainly composed of silicone resin are used in process paper for green sheet molding used in the manufacture of ceramic electronic components, polarizing plates, and adhesive separators for optical components used in the manufacture of flat panel displays such as optical filters.

[0003] As the above-mentioned polyester resin substrates are used in a wide variety of applications, the amount of waste and used products generated is increasing, leading to the deterioration of the global environment. To resolve this problem and promote the recycling of polyester resin substrates, it is preferable to reuse them by removing the coating film.

[0004] One example of such technology is Patent Document 1. Patent Document 1 discloses that an environmentally friendly polyester film can be used for inspection when laminated to an adhesive layer, while also possessing identifiability and discriminability. This film has a positive maximum value at 310-410 nm in the absolute reflectance spectrum at wavelengths of 300-800 nm, its total light transmittance and haze satisfy predetermined ranges, and its silicon content is 700 ppm or more. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-17964 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the polyester film described in Patent Document 1 contains a large amount of silicon, which leads to a problem in that silicon accumulates in the dead space of the equipment during the manufacturing process of the polyester film and aggregates, generating coarse foreign matter.

[0007] The present invention has been made in view of the above problems, and its purpose is to provide a polyester resin molded article that is suitable for manufacturing environmentally friendly polyester products, possessing high runability, smoothness with low levels of foreign matter, and other desirable properties. [Means for solving the problem]

[0008] As a result of studies conducted to solve the above problems, the inventors of the present invention have found that when forming a polyester resin molded article using a polyester resin support obtained by removing the coating film containing silicon from a polyester resin substrate having said coating film, the above objective can be achieved by setting the silicon content derived from the coating film in the polyester resin molded article to a predetermined range, and have completed the present invention.

[0009] One aspect of the present invention relates to a polyester resin molded article, which is molded using a polyester resin support obtained by removing the coating film from a polyester resin substrate having a polyester resin support and at least one layer of silicon-containing coating film, wherein the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article.

[0010] Another aspect of the present invention relates to a polyester product obtained using the above-described polyester resin molded article.

[0011] Another aspect of the present invention relates to a method for producing a polyester resin molded article, comprising the following steps (3) and (5). (3) A step of removing the coating film from a polyester resin substrate having at least one layer of silicon-containing coating film on at least a portion of the polyester resin support to obtain the polyester resin support. (5) A step to obtain a polyester resin molded article by molding the obtained polyester resin support, and in the polyester resin molded article, the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a polyester resin molded article that is suitable for manufacturing environmentally friendly polyester products, possessing high runability, smoothness with minimal foreign matter, and other desirable properties. [Modes for carrying out the invention]

[0013] The present invention will be described in detail below based on embodiments. Furthermore, the present invention is not limited in any way to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In this specification, the "~" indicating a numerical range means, unless otherwise specified, that the numbers before and after it are included as the lower and upper limits.

[0014] <Polyester resin support> The polyester resin support in this embodiment is formed by comprising a polyester composition. The polyester composition is not particularly limited, but examples include polyesters obtained by polycondensation of a dicarboxylic acid component and a diol component.

[0015] Examples of the dicarboxylic acid component include various dicarboxylic acid components such as aromatic dicarboxylic acids, linear aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Specifically, for example, terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, phthalic acid, etc. can be mentioned.

[0016] As the diol component, aliphatic glycols are preferred. For example, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc. can be mentioned. In addition to diols, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used.

[0017] The polyester resin support may be a homopolyester resin support or a copolymerized polyester resin support. Further, the polyester resin support may contain a third component other than the dicarboxylic acid component and the diol component as a copolymerization component.

[0018] As the polyester resin support, a polyester resin support mainly composed of polyethylene terephthalate, polyethylene naphthalate, etc. is preferably used. More preferably, it is polyethylene terephthalate. Also, these may be copolymerized polyesters.

[0019] The polyester resin support may be composed of a polyester composition, or may contain additives other than polyester in the composition. Examples of the additives include end-capping agents, antioxidants, flame retardants, fluorescent brighteners, matting agents, plasticizers, or defoaming agents, etc.

[0020] A commercially available polyester resin support may be used, or when manufacturing, it can be produced, for example, by the following method.

[0021] For example, raw polyester resin chips are vacuum-dried, then supplied to an extruder, melted at 260-300°C, extruded into a sheet through a T-shaped die, and wrapped around a mirror-finish casting drum with a surface temperature of 10-60°C using an electrostatic casting method, where it is cooled and solidified to produce an unstretched polyester resin support. The unstretched polyester resin support is stretched 2.5-5 times in the longitudinal direction between rolls heated to 70-130°C. Subsequently, it is stretched 2.5-5 times in the width direction in a continuous hot air zone heated to 70-150°C. Then, it is led to a heat treatment zone at 190-240°C, subjected to heat treatment for 5-40 seconds, and then completed crystal orientation through a cooling zone at 100-200°C to obtain a polyester resin support. In addition, a relaxation treatment of 0.1-12% in the width direction or longitudinal direction may be applied as needed during the above heat treatment.

[0022] In this embodiment, the thickness of the polyester resin support is not particularly limited, but considering handling properties such as strength and rigidity, it is preferably 5 μm to 500 μm. More preferably, the thickness of the polyester resin support is 10 μm to 200 μm, and particularly preferably 20 μm to 100 μm.

[0023] <Coated film> In the polyester resin substrate of this embodiment, the polyester resin support has at least one silicon-containing coating film on at least a portion of its surface. The coating film is not particularly limited as long as it is a film that can impart various functions to the polyester resin support, and examples include a release film, an adhesive film, a hard coat film, an easy-adhesion film, and an antistatic film.

[0024] In a polyester resin substrate, the coating film may be present on at least one side of the polyester resin substrate, or on both sides. Furthermore, in a polyester resin substrate, the coating film may consist of a single silicon-containing film, or it may consist of two or more layers. In addition, the coating film may have not only a single function but also multiple functions. When two or more coating films are provided, at least one of them may be a silicon-containing coating film, or a silicon-containing coating film and a silicon-free coating film may be provided.

[0025] A silicon-containing coating film may include, for example, a silicone compound, a silane compound, or other silicon compound as a silicon source, and more preferably one that includes a silicone compound.

[0026] If the coating film is a release film, the release film may be composed of a resin. The resin constituting the release film is not particularly limited as long as it contains silicon, and examples include silicone-based resins such as polydimethylsiloxane. Furthermore, the resin constituting the release film may be used alone or in combination of two or more types.

[0027] The method for forming a coating film on a polyester resin substrate is not particularly limited, but for example, reverse coating, gravure coating, rod coating, bar coating, wire bar coating, die coating, spray coating, etc., can be used.

[0028] The thickness of the coating film (or the total thickness if there are multiple coating films) is preferably 0.005 μm or more and 50 μm or less. To effectively perform the desired function, the above thickness is more preferably 0.01 μm or more. On the other hand, if the coating film is too thick, it may take a long time to remove it.

[0029] <Polyester resin base material> The polyester resin substrate in this embodiment includes the polyester resin support and the coating film formed on at least a portion of its surface.

[0030] The polyester resin substrate may have other layers in addition to the polyester resin support and the coating film. Examples of other layers include a ceramic slurry layer and an adhesive layer. The other layers may be formed on at least a portion of the surface of the polyester resin substrate opposite to the coating film, or on at least a portion of the surface of the coating film.

[0031] The shape of the polyester resin substrate is not particularly limited and may be, for example, in the form of a film, fiber, or sheet.

[0032] When the polyester resin substrate is a film, its thickness is not particularly limited, but it can usually be set appropriately within the range of 10 to 70 μm.

[0033] <Recycled polyester resin support> In this embodiment, the polyester resin support is recovered by removing the coating film from the polyester resin substrate. In this embodiment, the recovered polyester resin support may be referred to as the recovered polyester resin support. As a method for removing the coating film, for example, the <step (3) for removing the coating film> described later can be used.

[0034] On the surface of the recovered polyester resin support, trace amounts of the coating film and other layers that were not removed may remain. The degree of removal of these can be adjusted, for example, by the concentration of the solvent used in the step (3) for removing the coating film, and the contact time with the solvent.

[0035] <Polyester resin molded product> The polyester resin molded article in this embodiment is obtained by molding the recovered polyester resin support obtained by removing the coating film from the polyester resin substrate. That is, the polyester resin molded article in this embodiment can be suitably manufactured by the method for manufacturing a polyester resin molded article described later, and is obtained through at least the steps of removing the coating film (3) and molding the recovered polyester resin support (5) described later. By obtaining the polyester resin molded article in this way, the polyester resin substrate can be recycled efficiently.

[0036] In this embodiment, the polyester resin molded article has a silicon content derived from the coating film of 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article. By setting the silicon content derived from the coating film to 50 ppm or more, minute irregularities can be created on the surface of the polyester product, resulting in a polyester resin molded article suitable for manufacturing polyester products with excellent runability and high processability. Furthermore, by setting the silicon content to 500 ppm or less, a decrease in smoothness due to the generation of coarse protrusions due to silicone aggregation can be prevented. The silicon content derived from the coating film is 50 ppm or more, preferably 100 ppm or more, and more preferably 150 ppm or more. The silicon content derived from the coating film is 500 ppm or less, preferably 400 ppm or less, and more preferably 300 ppm or less.

[0037] The shape of the polyester resin molded article is not particularly limited and may be in the form of flakes, pellets, or chips, for example.

[0038] <Polyester products> The polyester product in this embodiment is obtained using the above-described polyester resin molded article. As a method for manufacturing the polyester product, for example, the method for manufacturing a polyester product using a polyester resin molded article, as described later, can be used.

[0039] The polyester product is not particularly limited and can be used for general polyester applications, such as manufacturing polyester films, PET bottles, polyester fibers, polyester sheets, and polyester containers. Specifically, it can be used as a polyester film. In other words, the polyester product in this embodiment is preferably a film.

[0040] When a polyester product is a film, its thickness is not particularly limited, but it can usually be set appropriately within the range of 10 to 50 μm.

[0041] Polyester products can be coated with a film as needed. Examples of such films include release films, adhesive films, hard coat films, easy-adhesion films, and antistatic films.

[0042] The polyester product obtained in this way can also be used again in the production of the polyester resin molded article in this embodiment. That is, the coating film can be removed from the polyester product to obtain a recovered polyester resin support, and then the polyester resin molded article can be formed.

[0043] As described above, the polyester products manufactured from the polyester resin molded articles obtained again are not particularly limited and can be used for ordinary polyester applications. Examples of polyester applications include polyester films, PET bottles, polyester fibers, polyester sheets, and polyester containers, similar to those described above.

[0044] If the polyester product is a film, its structure is not particularly limited and may be a single-layer structure or a laminated structure. If the polyester film has a laminated structure, it may be a two-layer structure, a three-layer structure, or a four-layer or more multi-layer structure.

[0045] The polyester film is preferably a laminated structure consisting of at least three layers, having a first surface layer, an intermediate layer, and a second surface layer in that order, or it may be a laminated structure consisting of only these three layers. It is more preferable that the intermediate layer contains the polyester resin molded article of this embodiment.

[0046] When the intermediate layer contains a polyester resin molded product, the content of the polyester resin molded product in the intermediate layer is preferably 10% by mass or more, and more preferably 30% by mass or more. If the content of the polyester resin molded product is too low, the minute irregularities caused by silicon from the coating film will decrease, resulting in poor smoothness of the polyester film.

[0047] The materials of the first and second surface layers may be the same or different. Examples of materials for the first and second surface layers include polyester.

[0048] <Method for manufacturing polyester resin molded articles> The method for manufacturing a polyester resin molded article in this embodiment includes the following steps (3) and (5). (3) A step to obtain the polyester resin support by removing the coating film from a polyester resin substrate having at least one layer of silicon-containing coating film on at least a portion of the polyester resin support. (5) A step to obtain a polyester resin molded article by molding the obtained polyester resin support, and in the polyester resin molded article, the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article.

[0049] This configuration makes it possible to manufacture polyester resin molded articles that are suitable for producing environmentally friendly polyester products, possessing high drivability, smoothness with minimal foreign matter, and excellent run-through properties.

[0050] In the method for manufacturing a polyester resin molded article, the polyester resin support, coating film, polyester resin substrate, recovered polyester resin support, and polyester resin molded article are the same as those described above. <Step (3) to remove the coating film> The step (3) of removing the coating film is not particularly limited, as long as the silicon content derived from the coating film in the resulting polyester resin molded article is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article. As a method for removing the coating film, for example, one may bring at least the surface of the polyester resin substrate having the coating film into contact with a solvent.

[0051] Examples of the solvents mentioned above include alkaline treatment solutions. These solvents may be used alone or in combination of two or more. They may also contain surfactants, ultrafine bubbles, alcohols, etc., as will be described later.

[0052] Examples of alkaline treatment solutions include solutions in which an alkaline substance is dissolved. While not particularly limited, examples of alkaline substances include sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide; sodium silicate, potassium silicate, ammonium silicate; sodium distodium phosphate, potassium distodium phosphate, ammonium distodium phosphate; sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate; sodium carbonate, potassium carbonate, ammonium carbonate; sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate; and inorganic alkaline agents such as sodium borate, potassium borate, and ammonium borate. Of these, alkali metal hydroxide salts are preferred, with sodium hydroxide and potassium hydroxide being more preferred. The above alkaline substances may be used individually or in combination of two or more.

[0053] While there are no particular limitations on the solvent used to dissolve alkaline substances, water is one example.

[0054] The concentration of the alkaline substance in the above-mentioned alkaline treatment solution is preferably 0.01% by mass or more and 15% by mass or less, more preferably 0.04% by mass or more and 15% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less. If the concentration of the alkaline substance is too high, the polyester resin support tends to be easily damaged, and if the concentration is too low, there is a risk that the coating film cannot be sufficiently removed. When the content of the alkaline substance is within the above range, the coating film removal effect can be obtained and damage to the polyester resin support can be suppressed.

[0055] The solvent used to remove the coating film may contain surfactants, ultrafine bubbles, or alcohols as auxiliary agents to prevent the removed coating film from reattaching and to improve the efficiency of coating film removal.

[0056] There are no particular restrictions on the surfactant used, but examples include nonionic surfactants, cationic surfactants, and anionic surfactants. Surfactants may be used individually or in combination of two or more types.

[0057] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene sorbitan fatty acid esters.

[0058] Examples of cationic surfactants include alkylpyridinium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, and alkyldimethylbenzylammonium chloride.

[0059] Examples of anionic surfactants include sodium alkyl sulfate salts, sodium alkylbenzene sulfonate salts, sodium dialkyl succinate sulfonate salts, sodium alkyl diphenyl ether disulfonate salts, sodium polyoxyethylene alkyl ether sulfate salts, and sodium polyoxyethylene alkylphenyl ether sulfate salts.

[0060] Ultrafine bubbles are tiny bubbles with a diameter of less than 1 μm. Ultrafine bubbles can be supplied by conventional methods.

[0061] As the alcohol, the alcohols exemplified in the following step (2) of contacting the product with a surfactant, alcohol, or an aqueous solution of a surfactant or alcohol can be suitably used.

[0062] The solvent may contain other additives as long as they do not interfere with the effects of the present invention. Examples of additives include antioxidants, pH adjusters, and defoamers.

[0063] The solvent temperature is preferably less than 100°C, more preferably between 65°C and 100°C, and even more preferably between 65°C and 95°C. A solvent temperature of 65°C or higher is preferable because it does not cause changes in the physicochemical properties of the polyester resin support and allows for the acquisition of a high-quality polyester resin support with few impurities without requiring excessive time. Furthermore, a solvent temperature of less than 100°C allows for achievement at atmospheric pressure, prevents the need for large-scale equipment, and suppresses hydrolysis and dissolution of the polyester resin support due to heating.

[0064] The contact time between the solvent and the polyester resin substrate is preferably more than 0 seconds and less than 700 seconds, more preferably more than 0 seconds and 600 seconds or less, even more preferably more than 0 seconds and 180 seconds or less, and particularly preferably more than 0 seconds and 120 seconds or less. If the contact time is too long, the polyester resin support tends to be easily damaged, and there is a risk that the burden on wastewater treatment of the alkaline treatment solution will increase as the polyester resin support dissolves in the alkaline treatment solution. The contact time with the solvent should be such that the coating film is sufficiently dissolved and swollen, but if the contact time is too short there is a risk that the coating film will not be sufficiently removed, so it is more preferably 1 second or more, and even more preferably 5 seconds or more. When the contact time with the solvent is within the above range, the coating film removal effect can be obtained and damage to the polyester resin support can be suppressed.

[0065] The solvent treatment conditions can be appropriately selected depending on the type and thickness of the polyester resin support and coating film. However, in order to obtain a polyester resin molded article having a silicon content of 50 ppm to 500 ppm derived from the coating film, based on the weight of the polyester resin molded article, it is preferable to contact at least the surface of the polyester resin substrate having the coating film with an alkaline treatment solution at a temperature of less than 100°C and an alkali concentration of 0.01 to 15% by mass for more than 0 seconds but less than 700 seconds, and more preferably to contact it with an alkaline treatment solution at a temperature of 65°C to less than 100°C and an alkali concentration of 0.04% to 15% by mass for more than 1 second but less than 180 seconds.

[0066] <Step (2) of contacting with a surfactant, alcohol, or an aqueous solution in which a surfactant or alcohol is dissolved> The method of this embodiment may include a step (2) of contacting at least the surface of the polyester resin substrate having a coating film with a surfactant, alcohol, or an aqueous solution of a surfactant or alcohol before the step (3) of removing the coating film. By contacting the surface of the polyester resin substrate with a surfactant, alcohol, or an aqueous solution of a surfactant or alcohol and allowing it to penetrate the coating film, the surface of the polyester resin substrate is made hydrophilic. By contacting the solvent with the surface of the polyester resin substrate in a hydrophilic state beforehand, the penetration of the solvent is promoted, making it easier to remove the coating film from the polyester resin substrate quickly and efficiently.

[0067] The method of contacting a surfactant, alcohol, or an aqueous solution of a surfactant or alcohol is not particularly limited as long as at least the surface of the polyester resin substrate having a coating film can be in contact. For example, methods include immersing the polyester resin substrate in a cleaning tank containing a surfactant, alcohol, or an aqueous solution of a surfactant or alcohol, coating the substrate, or spraying the solution. Of these, immersion is preferred from the viewpoint of the penetration of the surfactant, alcohol, or aqueous solution of a surfactant or alcohol into the coating film.

[0068] There are no particular restrictions on the type of alcohol used; it can be monohydric or polyhydric, and it can be lower or higher alcohol.

[0069] Examples of monohydric alcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonylnol, decylnol, undecylnol, dodecylnol, methoxyethanol, methoxypropanol, methoxybutanol, methoxyethoxyethanol, ethoxyethanol, ethoxyethoxyethanol, ethoxypropanol, ethoxybutanol, butoxyethanol, butoxypropanol, and butoxybutanol.

[0070] Examples of polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, glycerin, and polyoxyalkylene polyols.

[0071] Among these, monohydric lower alcohols such as methanol, ethanol, 1-propanol (n-propanol), and 2-propanol (isopropanol) are more preferred, at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol is even more preferred, and methanol and ethanol are particularly preferred.

[0072] Alcohol can be used alone or in combination of two or more types.

[0073] The concentration of the aqueous solution containing the dissolved alcohol is preferably between 0.1% by mass and 100% by mass, with a lower limit of 30% by mass or higher being more preferable. If the alcohol concentration is too low, there is a risk that the coating film cannot be sufficiently removed. When the concentration of the aqueous solution containing the dissolved alcohol is 30% by mass or higher, a sufficient coating film removal effect can be obtained.

[0074] The temperature of the alcohol or aqueous solution of alcohol should be adjusted depending on the alcohol used, but it is preferably 50°C or lower, and more preferably room temperature between 5 and 30°C. If the temperature of the alcohol or aqueous solution of alcohol is too high, the alcohol may boil. When the temperature of the alcohol or aqueous solution of alcohol is 50°C or lower, it is below the boiling point of alcohol, thus promoting the removal effect of the coating film.

[0075] There are no particular restrictions on the surfactant, but examples include at least one surfactant selected from the group consisting of nonionic surfactants, cationic surfactants, and anionic surfactants. Nonionic surfactants are particularly preferred. Surfactants may be used alone or in combination of two or more types.

[0076] Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkylphenol ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether; polyoxyethylene alkylaryl ethers; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate; polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan moreoleate, and polyoxyethylene sorbitan trioleate; and glycerin fatty acid esters such as monoglyceride stearate.

[0077] Examples of cationic surfactants include alkylpyridinium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, and alkyldimethylbenzylammonium chloride.

[0078] Examples of anionic surfactants include sodium alkyl sulfate salts, sodium alkylbenzene sulfonate salts, sodium dialkyl succinate sulfonate salts, sodium alkyl diphenyl ether disulfonate salts, sodium polyoxyethylene alkyl ether sulfate salts, and sodium polyoxyethylene alkylphenyl ether sulfate salts.

[0079] The concentration of the aqueous solution containing the surfactant is preferably 0.00001% to 100% by mass, more preferably 0.0001% to 100% by mass, even more preferably 0.001% to 50% by mass, and particularly preferably 0.01% to 1% by mass. If the surfactant concentration is too low, there is a risk that the coating film cannot be sufficiently removed. A concentration of 0.00001% to 100% by mass of the surfactant or aqueous solution containing the surfactant is preferable because it provides a sufficient coating film removal effect.

[0080] The temperature of the surfactant or the aqueous solution containing the surfactant should be adjusted depending on the surfactant used, but it is preferable to keep it below 50°C. Keeping the temperature of the surfactant or aqueous solution below 50°C allows for a higher concentration of the surfactant, thereby promoting the removal of the coating film. Note that nonionic surfactants become insoluble in water at excessively high temperatures, so it is preferable to treat them at a temperature below the cloud point of the surfactant.

[0081] The contact time between the polyester resin substrate and the surfactant, alcohol, or aqueous solution of the surfactant or alcohol is preferably 120 seconds or less, more preferably 0.001 to 60 seconds, even more preferably 0.001 to 10 seconds, and particularly preferably 0.1 to 10 seconds. If the contact time with the polyester resin substrate is too short, the coating film may not be sufficiently removed, and if the contact time is too long, the size of the apparatus may increase, worsening economic efficiency and operability. A contact time of 120 seconds or less with the polyester resin substrate provides good economic efficiency and operability, and enhances the coating film removal effect.

[0082] The above-mentioned surfactant, alcohol, or aqueous solution of the surfactant or alcohol may contain ultrafine bubbles as an auxiliary agent to enhance the efficiency of removing the coating film. Furthermore, the alcohol or aqueous solution of the alcohol may contain the above-mentioned surfactant, and the surfactant or aqueous solution of the surfactant may contain the above-mentioned alcohol.

[0083] <Step (1) of surface modification treatment> The method of this embodiment may include, before step (3) of removing the coating film, step (1) of surface modification treatment on the surface of the coating film on the polyester resin substrate with a surfactant, alcohol, or an aqueous solution of the surfactant or alcohol, and for the purpose of increasing affinity with the solvent.

[0084] The surface modification treatment is not particularly limited, and known methods can be employed, such as corona discharge treatment, plasma treatment, glow discharge treatment, flame treatment, or ultraviolet treatment, and it is preferable to perform at least one treatment selected from the group consisting of these.

[0085] The surface modification treatment may be performed before step (3) of removing the coating film, but it is more preferable to perform it before step (2) of contacting the surface with a surfactant, alcohol, or an aqueous solution containing a surfactant or alcohol in order to increase the affinity with the surfactant, alcohol, or aqueous solution containing a surfactant or alcohol.

[0086] If analysis by X-ray photoelectron spectroscopy after surface modification treatment shows a decrease of 0.1% or more in the proportion of CC bonds and CH bonds, it is possible to obtain an effect that increases affinity with surfactants, alcohols, aqueous solutions containing surfactants or alcohols, or alkaline treatment solutions.

[0087] For corona discharge treatment, the treatment intensity is 10-1000 Wmin / m 2 Preferably, the power output is 20-200 Wmin / m 2 More preferably, 40-120 Wmin / m 2 This is even more preferable. If the treatment strength is too high, the polyester resin support tends to be more susceptible to damage, and if the treatment strength is too low, the alkali treatment time becomes longer, which also tends to make the polyester resin support more susceptible to damage.

[0088] Furthermore, the power density of the corona discharge machine used is preferably 4 to 20 W / cm².2 Therefore, a uniform surface treatment can be applied.

[0089] For UV treatment, the irradiation intensity is 0.5 to 40 mW / cm². 2 Preferably, it is 10-40 mW / cm². 2 More preferably, 15-40 mW / cm² 2 This is even more preferable. If the irradiation intensity is too high, the polyester resin support tends to be more susceptible to damage, and if the irradiation intensity is too low, the alkali treatment time becomes longer, which also tends to make the polyester resin support more susceptible to damage.

[0090] The UV irradiation time is preferably 3 to 210 seconds, more preferably 30 to 100 seconds, and even more preferably 50 to 70 seconds. If the UV irradiation time is too long, the size of the device needs to be increased, which increases manufacturing costs, and the polyester resin support tends to be more susceptible to damage. If the UV irradiation time is too short, there is a risk that the coating film will not be sufficiently removed.

[0091] Furthermore, it is preferable to use electromagnetic waves of invisible light with a wavelength of 10 to 400 nm, that is, shorter than visible light and longer than soft X-rays, for irradiation.

[0092] Examples of ultraviolet light sources include well-known lamps such as ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, and metal halide lamps, with low pressure mercury lamps being preferred.

[0093] <Rinse process (4)> The method of this embodiment preferably includes a step (4) of washing the recovered polyester resin support after the step (3) of removing the coating film. The washing is performed to remove any trace amounts of coating film remaining on the recovered polyester resin support after the step (3) of removing the coating film, and to remove any solvent remaining on the recovered polyester resin support after the above step (3).

[0094] The temperature of the water washing process in step (4) of the recovered polyester resin support is not particularly limited, but for example, washing with hot water at a temperature of approximately 40°C to 100°C will further enhance the effectiveness of the above-mentioned effects.

[0095] Methods of washing include spraying water onto the recovered polyester resin support from which the coating film has been removed, and immersing the recovered polyester resin support in a water tank. Physical cleaning such as using a roller brush, microbubbles, or water jet may also be performed during the washing process.

[0096] The rinsing time is preferably 0.01 seconds to 20 minutes, and more preferably 0.1 seconds to 2 minutes. If the rinsing time is too short, there is a risk that the residual coating film will not be sufficiently removed, which may increase the silicon content in the polyester resin molded body and increase the amount of foreign matter in the film produced from the polyester resin molded body of this embodiment. If the rinsing time is too long, it will lead to a deterioration of the washing time cycle in the batch washing process, and the washing equipment will become excessively large in the roll-to-roll washing process.

[0097] [Drying process] After rinsing with water, it is preferable to perform a drying treatment to remove any remaining water on the recovered polyester resin support.

[0098] The drying time is preferably 10 seconds to 5 minutes. A drying time of 10 seconds or more ensures sufficient drying and suppresses blocking. More preferably, it is 30 seconds or more. Furthermore, a drying time of 5 minutes or less prevents deformation of the recovered polyester resin support.

[0099] The drying method is not particularly limited and can include, for example, hot air drying, which involves blowing hot air onto the material, or heat drying, which involves heating with a non-contact heater.

[0100] <Step (5) of molding the recovered polyester resin support> Step (5) for molding the recovered polyester resin support obtained in the above process to produce a polyester resin molded article specifically includes, for example, methods of flakeping, pelletizing, or chipping the recovered polyester resin support.

[0101] The method of flaking, pelletizing, or chipping is not particularly limited, and known methods can be used.

[0102] <Method for manufacturing polyester products using polyester resin molded articles> The method for manufacturing polyester products using a polyester resin molded article is not particularly limited, and known methods can be appropriately adopted depending on the target polyester product.

[0103] For example, a polyester resin molded body may be formed into various polyester products such as polyester films by melt extrusion or the like.

[0104] When the polyester product is a film and has a laminated structure, examples of its manufacturing method include the method described in Japanese Patent Application Publication No. 2014-133373.

[0105] As described above, the following configuration is disclosed in this specification. <1> A polyester resin molded article, molded using a polyester resin support obtained by removing the coating film from a polyester resin substrate having a polyester resin support and at least one layer of silicon-containing coating film, wherein the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article. <2> The coating film contains a silicone compound. <1> A polyester resin molded article as described above. <3> The polyester resin substrate is a film. <1> or <2> A polyester resin molded article as described above. <4> The coating film is removed by contacting at least the surface of the polyester resin substrate having the coating film with an alkaline treatment solution. <1> ~ <3> A polyester resin molded article according to any one of the following. <5> <1> ~ <4> A polyester product obtained using a polyester resin molded article described in any one of the following. <6> The aforementioned polyester product is a film. <5> Polyester products as described above. <7> The polyester product has a laminated structure consisting of at least three layers, having a first surface layer, an intermediate layer, and a second surface layer in that order. <6> Polyester products as described above. <8> The intermediate layer contains the polyester resin molded body. <7> Polyester products as described above. <9> A method for producing a polyester resin molded article, comprising the following steps (3) and (5). (3) A step to obtain the polyester resin support by removing the coating film from a polyester resin substrate having at least one layer of silicon-containing coating film on at least a portion of the polyester resin support. (5) A step to obtain a polyester resin molded article by molding the obtained polyester resin support, and in the polyester resin molded article, the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article. [Examples]

[0106] The embodiments of the present invention will be described in more detail below based on examples, but are not necessarily limited thereto. Unless otherwise specified below, "%" means mass%, and "parts" means parts by mass.

[0107] 1. Evaluation of silicon content in polyester resin molded products The substance was quantified using alkali fusion-nitric acid dissolution-ICP emission spectrometry (ICP-AES).

[0108] 2. Evaluation of foreign matter in polyester resin molded products One g of a polyester resin molded product was dissolved in 20 ml of a phenol / 1,1,2,2,tetrachloroethane = 60 / 40 solution, filtered through filter paper, and the number of black foreign particles (17 μm or larger) on the filter paper surface was counted using a stereomicroscope (60x magnification). [Evaluation Criteria] ○ (Good): Fewer than 5 foreign objects. △ (Acceptable): Number of foreign objects is 5 or more but less than 10 × (Not allowed): More than 10 foreign objects.

[0109] 3. Evaluation of the running performance of polyester products Two polyester films were prepared, overlapped, and placed on a glass plate. The first surface of the lower film was positioned so that it was in contact with the second surface of the upper film. A 200g weight (contact area 40cm²) was placed on top of the overlapping films. 2 A glass plate was placed. One end of the lower film (the side facing the direction of movement) was fixed to the glass, and one end of the upper film (the end opposite to the direction of movement) was fixed to the detector. The coefficient of static friction (μs) when the glass plate was moved 5 mm at a speed of 2 mm / sec was calculated using the following formula. μs = (Initial tension) / (Load of 200g) The evaluation criteria were as follows: [Evaluation Criteria] 〇(Good running performance): μs=0.4 or less △ (Drivable): μs greater than 0.4 and 0.5 or less × (Not drivable): μs = 0.5 or greater

[0110] 4. Evaluation of coarse protrusions in polyester products A cut sample of A4 size was cut from an arbitrary position in the width direction of the polyester film, ensuring that the longitudinal direction of the film matched the longitudinal direction of the A4 cut sample. Using the crossed nicol method, a Fujicolor Lightbox 100V 8W (manufactured by Shinkosha Co., Ltd.) was used as the light source. A normal analyzer and polarizer were placed on top of it so that their absorption axes were perpendicular, with the polyester film sandwiched between them. Visual inspection was then performed from the polarizer side. At this time, the absorption axis of the polarizer, with dimensions of 28cm wide x 34cm long on the observation surface side, was aligned with the longitudinal direction of the film in the A4 cut sample. The visual inspection first involved identifying the location and number of 50 foreign objects or defects in the polarizer that appeared as bright spots without the polyester film. Next, with the polyester film in place, the number of bright spots that could no longer be identified was counted. The evaluation criteria were as follows. [Evaluation Criteria] ○ (Good smoothness): The number of bright spots that become invisible is less than 5. △ (Smoothing possible): The number of bright spots that become undetectable is 5 or more but less than 15. × (Smoothing not possible): 15 or more bright spots that can no longer be identified.

[0111] (Preparation of sample film) As described below, a laminated polyester film having a release film was prepared as the sample film (polyester resin substrate). 1. A polyethylene terephthalate film (Toray Industries, Inc.'s "Lumirror" T60, 38 μm thick, with an intrinsic viscosity of 0.61) was prepared as a polyester resin support. A 5% toluene solution of curable silicone resin (containing 100 parts of Toray Dow Corning Silicone Co., Ltd.'s LTC-350B and 0.8 parts of its curing agent SRX-212) was coated onto one side of the film using a bar coater, and heated in a tunnel oven at 100°C to form a release film as a coating on the surface of the polyester resin support. The release film was thus prepared and wound up.

[0112] 2. Application of ceramic slurry and conductive paste On the release film surface of the above-mentioned release film, a ceramic slurry having the following composition was uniformly applied with a blade coater. This was dried at 85°C in a tunnel oven to form a ceramic layer with a thickness of 20 μm on the release film. Next, a conductive paste having the following composition was screen printed on the ceramic layer, dried at 80°C for 10 minutes to form an electrode, and then left standing at 20°C for 1 hour. 《Ceramic Slurry Composition》 Ceramic powder (barium titanate): 100 parts Binder (polyvinyl butyral): 10 parts Plasticizer (dioctyl phthalate): 5 parts Solvent (toluene / isopropyl alcohol = 1 / 1 (mass ratio)): 100 parts 《Conductive Paste Composition》 Ni-based powder: 90 parts Organic vehicle: 10 parts Terpineol: 30 parts

[0113] 3. Peeling of Ceramic Layer and Electrode On the release film on which the above-mentioned ceramic layer and electrode were formed, a slit was made in a 10 cm × 10 cm shape only in the release film of the portion where the ceramic layer and electrode were formed, and then the ceramic layer and electrode were sucked with a vacuum suction machine and peeled from the release film to obtain a long sample film. Note that the surface of the release film of the sample film was in a state where the ceramic layer and electrode that could not be partially peeled were attached.

[0114] [Example 1] (Step (1) of performing surface modification treatment) The surface on the release film side of the sample film was subjected to corona discharge treatment with a corona discharge treatment device at a power density of 8 W / cm 2 , and a treatment intensity of 60 Wmin / m 2 to perform corona discharge treatment.

[0115] (Step (2) of contacting with a surfactant, alcohol, or an aqueous solution in which a surfactant or alcohol is dissolved) A sample film treated with corona discharge was immersed for 1 second in a 0.03 wt% aqueous solution of a nonionic surfactant ("Polyoxyethylene (10) Octylphenyl Ether," manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) at room temperature (25°C).

[0116] (Step (3) to remove the coating film) A 1000L aqueous solution of 3% sodium hydroxide and 0.03% nonionic surfactant ("Polyoxyethylene (10) Octylphenyl Ether" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was heated to 80°C to create an alkaline treatment solution. The sample film was then transported through this solution at 70 m / s and exposed to the alkaline treatment solution for 20 seconds to remove the release film and obtain a recovered polyester resin support.

[0117] (washing and drying) The sample film (recovered polyester resin support) was immersed in a water tank for 45 seconds, and then dried by blowing hot air onto it.

[0118] (Pelletization (5) - Process for molding the recovered polyester resin support)) The dried sample film described above was crushed, fed into an extruder, melted, and pelletized. The resulting pellets were used to perform the "evaluation of silicon content in polyester resin molded articles" and the "evaluation of foreign matter in polyester resin molded articles" described above.

[0119] (Manufacturing of polyester film) A laminated polyester film (polyester product according to this embodiment) consisting of three layers, with a first surface layer, an intermediate layer, and a second surface layer in that order, using pellets obtained from the sample film as the intermediate layer, was prepared as follows.

[0120] • Preparation of polyester pellets for surface layer ...Production of polyester pellet A 86.5 parts by weight of terephthalic acid and 37.1 parts by weight of ethylene glycol were esterified at 255°C while distilling off water. After the esterification reaction was complete, 0.02 parts by weight of trimethyl phosphate, 0.06 parts by weight of magnesium acetate, 0.01 parts by weight of lithium acetate, and 0.0085 parts by weight of antimony trioxide were added. Subsequently, under vacuum, the mixture was heated to 290°C and the temperature was increased to carry out a polycondensation reaction to obtain polyester pellets A with an intrinsic viscosity of 0.63.

[0121] Preparation of polyester pellet B Polyester pellet A was mixed with an aqueous slurry of divinylbenzene / styrene copolymer crosslinked particles with a volume-average particle size of 0.3 μm using a vented twin-screw kneader to obtain polyester pellet B containing 0.2% by weight of divinylbenzene / styrene copolymer crosslinked particles with a volume-average particle size of 0.3 μm relative to the polyester.

[0122] For both the first and second surface layers, polyester pellets were used as raw materials in the following proportions. Polyester pellets A: 87.5% by mass Polyester pellets B: 12.5% ​​by mass

[0123] • Laminated molding The surface layer material was stirred in a blender and then supplied to a twin-screw extruder with a vent. The intermediate layer material was vacuum-dried at 160°C for 8 hours and then supplied to a single-screw extruder. After melt extrusion at 285°C and filtration with a high-precision filter that captures more than 95% of foreign matter larger than 5 μm, the material was cast onto a 20°C cast drum with electrostatic application in a 2-layer, 3-layer configuration (surface layer / intermediate layer / surface layer = 1 / 10 / 1 discharge volume) to obtain an unstretched sheet. This unstretched sheet was stretched 3.1 times in the longitudinal direction by a stretching roll heated to 90°C, then stretched 3.7 times in the width direction at 120°C using a tenter stretching machine, and then heat-set at 230°C and wound onto a roll to obtain a roll of biaxially oriented film with a thickness of 38 μm. The obtained film was used to perform the "evaluation of runability of polyester products" and the "evaluation of coarse protrusions of polyester products" described above.

[0124] [Example 2] After performing corona discharge treatment as a surface modification treatment, a polyester film was prepared in the same manner as in Example 1, except that the sample film used was cut into flakes.

[0125] [Example 3] A polyester film was prepared in the same manner as in Example 1, except that no surface modification treatment was performed.

[0126] [Examples 4-6] A polyester film was prepared in the same manner as in Example 3, except that the contact time with the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 1.

[0127] [Example 7] A polyester film was prepared in the same manner as in Example 1, except that step (2) of contacting the film with a surfactant, alcohol, or an aqueous solution of a surfactant or alcohol was not performed.

[0128] [Examples 8-11] A polyester film was prepared in the same manner as in Example 7, except that the contact time with the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 2.

[0129] [Examples 12, 13] A polyester film was prepared in the same manner as in Example 1, except that the temperature and contact time of the alkaline treatment solution in step (3) for removing the coating film were changed to the conditions shown in Table 2 or Table 3.

[0130] [Examples 14-18] A polyester film was prepared in the same manner as in Example 1, except that the alkali concentration and contact time of the alkaline treatment solution in step (3) for removing the coating film were changed to the conditions shown in Table 3.

[0131] [Examples 19-24] A polyester film was prepared in the same manner as in Example 1, except that the layer structure in the manufacturing of the polyester film was changed to the conditions shown in Table 4.

[0132] [Comparative Example 1] A polyester film was prepared in the same manner as in Example 1, except that the contact time with the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 5.

[0133] [Comparative Example 2] A polyester film was prepared in the same manner as in Example 1, except that the alkali concentration of the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 5.

[0134] [Comparative Example 3] A polyester film was prepared in the same manner as in Example 1, except that the temperature of the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 5.

[0135] [Comparative Example 4] A polyester film was prepared in the same manner as in Example 1, except that the contact time with the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 5.

[0136] [Comparative Example 5] A polyester film was prepared in the same manner as in Example 1, except that the alkali concentration of the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 5.

[0137] [Comparative Example 6] A polyester film was prepared in the same manner as in Example 1, except that the contact time with the alkaline treatment solution in step (3) for removing the coating film was changed to the conditions shown in Table 5.

[0138] The evaluation results for Examples 1-24 and Comparative Examples 1-6 are shown in Tables 1-5 below.

[0139] [Table 1]

[0140] [Table 2]

[0141] [Table 3]

[0142] [Table 4]

[0143] [Table 5]

[0144] As shown in Tables 1 to 5, according to Examples 1 to 24, by setting the silicon content derived from the coating film to 50 ppm or more and 500 ppm or less based on the weight of the polyester resin molded article, it is possible to provide a polyester product that combines running performance and suppression of coarse protrusions. This has enabled the provision of a polyester resin molded article suitable for the manufacture of environmentally friendly polyester products with excellent running performance and smoothness.

[0145] In contrast, Comparative Examples 1 and 2, where the silicon content derived from the coating film was 5 ppm based on the weight of the polyester resin molded article, and Comparative Example 3, where the silicon content was 10 ppm, exhibited poor smoothness. Furthermore, Comparative Examples 4 and 5, where the silicon content derived from the coating film was 600 ppm based on the weight of the polyester resin molded article, had many coarse protrusions. Comparative Example 6, where the silicon content derived from the coating film was 700 ppm, exhibited poor smoothness and many coarse protrusions.

[0146] As described above, the method of the present invention makes it possible to provide a polyester resin molded article suitable for the manufacture of environmentally friendly polyester products with excellent runnability and smoothness by setting the silicon content derived from the coating film within a predetermined range, and is extremely useful.

Claims

1. A polyester resin molded article, molded using a polyester resin support obtained by removing the coating film from a polyester resin substrate having a polyester resin support and at least one layer of silicon-containing coating film, wherein the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded article.

2. The polyester resin molded article according to claim 1, wherein the coated film contains a silicone compound.

3. The polyester resin molded article according to claim 2, wherein the polyester resin substrate is a film.

4. The polyester resin molded article according to any one of claims 1 to 3, wherein the coating film is removed by contacting at least the surface of the polyester resin substrate having the coating film with an alkaline treatment solution.

5. A polyester product obtained using the polyester resin molded article described in claim 1.

6. The polyester product according to claim 5, wherein the polyester product is a film.

7. The polyester product according to claim 6, wherein the polyester product has a laminated structure consisting of at least three layers, having a first surface layer, an intermediate layer, and a second surface layer in that order.

8. The polyester product according to claim 7, wherein the intermediate layer contains the polyester resin molded body.

9. A method for producing a polyester resin molded article, comprising the following steps (3) and (5). (3) A step to obtain the polyester resin support by removing the coating film from a polyester resin substrate having at least one layer of silicon-containing coating film on at least a portion of the polyester resin support. (5) A step of molding the obtained polyester resin support to obtain a polyester resin molded body, and in the polyester resin molded body, the silicon content derived from the coating film is 50 ppm or more and 500 ppm or less, based on the weight of the polyester resin molded body.

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