Method for producing terephthalic acid and method for decomposing object to be treated

Abstract

To provide a method for producing a terephthalic acid which can produce a terephthalic acid from an object to be treated containing polyethylene terephthalate with a good yield, while suppressing contamination of a reactor.SOLUTION: A method for producing a terephthalic acid includes a hydrolysis step of hydrolyzing an object to be treated including a molded article containing polyalkylene terephthalate as a main component, to which a curable resin composition or its cured product is attached, at a temperature of lower than 70°C, in the presence of monohydric alcohol, water and an inorganic strong base.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing terephthalic acid and a method for decomposing a material to be treated. [Background technology]

[0002] Due to the recent increase in environmental concerns, treatment and reuse of waste containing polyethylene terephthalate has been considered. As one of the methods for such reuse, various chemical recycling methods have been proposed.

[0003] For example, Patent Document 1 discloses a chemical treatment method for PET resin waste, which is characterized by maintaining the reaction temperature in the range of 140 to 200°C when hydrolyzing resin waste containing polyethylene terephthalate as the main component and mixed with foreign matter in the presence of alkali. Patent Document 2 discloses a method for monomerizing polyethylene terephthalate, in which polyethylene terephthalate in a homogeneous phase consisting of polyethylene terephthalate, dimethyl terephthalate, and methanol is thermally depolymerized under pressure so that methanol can exist in a liquid phase, and further methanol is added during the progress of the depolymerization. The temperature for thermal depolymerization is specifically set to 200 to 250°C. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-21374 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-072720 Summary of the Invention [Problem to be solved by the invention]

[0005] In the field of electrical and electronic components, various films containing polyethylene terephthalate as a base material are used to manufacture components, and the reuse of used films is being investigated. For example, a dry film of a solder resist comprises a layer of a solder resist composition on a polyethylene terephthalate film, and in some cases, a polyolefin film or the like is further provided thereon as a protective film. After peeling off the protective film from a solder resist dry film having such a structure, the solder resist dry film is placed on an object to be processed, such as a circuit board, so that the layer made of the solder resist composition is in contact with the object, and the layer made of the solder resist composition is photocured by irradiating it from the polyethylene terephthalate film side, after which the polyethylene terephthalate film is peeled off. The peeled polyethylene terephthalate film may still have the solder resist composition or a cured product of the solder resist composition (collectively referred to as "resist components") adhering to it. Such polyethylene terephthalate films are discarded as used films, and this waste may also contain polyolefin films, etc., which are the protective films that were peeled off during use.

[0006] When a polyethylene terephthalate film having resist components and the like attached thereto is treated as the treatment object by the methods described in Patent Documents 1 and 2, there is a problem that the resist components and the like attached to the treatment object react with each other and contaminate the reactor because the reaction temperature is high.

[0007] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional art and to provide a method for producing terephthalic acid, which can produce terephthalic acid in a good yield from a workpiece containing polyalkylene terephthalate as a main component and further containing a curable resin composition or a cured product thereof while suppressing contamination of a reactor. An object of the present invention is to provide a method for decomposing a treatment object containing polyalkylene terephthalate as a main component and further containing a curable resin composition or a cured product thereof, in a high yield while suppressing contamination of a reactor. [Means for solving the problem]

[0008] The present inventors have continued to study methods for producing terephthalic acid and have found that the above-mentioned problems can be solved by hydrolyzing a treatment target including a molded article containing polyalkylene terephthalate as a main component, the molded article having a curable resin composition or a cured product thereof adhered thereto, in the presence of a monohydric alcohol, water, and a strong inorganic base at a temperature of less than 70°C, thereby completing the present invention.

[0009] The gist and configuration of the present invention to solve the above problems is as follows.

[0010] [1] A method for producing terephthalic acid, comprising a hydrolysis step of hydrolyzing a workpiece, including a molded article containing polyalkylene terephthalate as a main component, to which a curable resin composition or a cured product thereof is attached, in the presence of a monohydric alcohol, water, and a strong inorganic base at a temperature of less than 70°C.

[0011] [2] The method for producing terephthalic acid according to [1], wherein the molded article containing the polyalkylene terephthalate as a main component is a film.

[0012] [3] The method for producing terephthalic acid according to [1] or [2], wherein the monohydric alcohol is a monohydric alcohol having 1 to 12 carbon atoms.

[0013] [4] The method for producing terephthalic acid according to any one of [1] to [3], wherein the inorganic strong base is an alkali metal hydroxide.

[0014] [5] The method for producing terephthalic acid according to any one of [1] to [4], wherein the hydrolysis is carried out in the hydrolysis step in the absence of a halogenated solvent.

[0015] [6] The method for producing terephthalic acid according to any one of [1] to [5], wherein the material to be treated further contains a polyolefin.

[0016] [7] The method for producing terephthalic acid according to any one of [1] to [6], wherein the hydrolysis step comprises mixing the material to be treated, the monohydric alcohol, and the inorganic strong base to obtain a mixture, and then mixing the mixture with water.

[0017] [8] a filtration step of filtering the product of the hydrolysis step to obtain a filtrate; The method for producing terephthalic acid according to any one of [1] to [7], further comprising a separation step of adding an acid to the filtrate and then filtering the filtrate to separate terephthalic acid.

[0018] [9] The method for producing terephthalic acid according to any one of [1] to [8], wherein the curable resin composition or the cured product thereof is derived from a solder resist composition.

[0019]

[10] A method for decomposing a treated object, including a molded article containing polyalkylene terephthalate as a main component and having a curable resin composition or a cured product thereof attached thereto, comprising a hydrolysis step of hydrolyzing the molded article in the presence of a monohydric alcohol, water, and a strong inorganic base at a temperature of less than 70°C. [Effects of the Invention]

[0020] According to the present invention, there can be provided a method for producing terephthalic acid, which can produce terephthalic acid in good yield from a workpiece containing polyalkylene terephthalate as a main component and further containing a curable resin composition or a cured product thereof while suppressing contamination of a reactor. Furthermore, according to the present invention, it is possible to provide a method for decomposing an object to be treated, which decomposes an object to be treated containing polyalkylene terephthalate as a main component and further containing a curable resin composition or a cured product thereof in a good yield while suppressing contamination of a reactor. DETAILED DESCRIPTION OF THE INVENTION

[0021] The method for producing terephthalic acid and the method for decomposing a material to be treated of the present invention will be described in detail below with reference to the embodiments.

[0022] In this specification, the expression "a to b" in the description of a range of values ​​means that the range is from a to b, unless otherwise specified.

[0023] <Method of producing terephthalic acid> The method for producing terephthalic acid of the present invention is characterized by comprising a step of hydrolyzing a workpiece, including a molded article containing polyalkylene terephthalate as a main component, having a curable resin composition or a cured product thereof adhered thereto, at a temperature of less than 70°C in the presence of a monohydric alcohol, water, and a strong inorganic base. Generally, polyalkylene terephthalate is poorly soluble in solvents, and therefore, polyalkylene terephthalate-containing materials are often recycled by heating them to a temperature above their melting point (e.g., 200°C or higher) to dissolve or disperse them in a solvent. However, such methods require high-temperature treatment, which consumes energy and is prone to undesirable reactions of the curable resin composition or cured product contained in the material, potentially contaminating the reactor. In particular, if the material contains a curable resin composition, the high-temperature treatment may cause the curable resin composition to react, potentially contaminating the reactor. On the other hand, the production method of the present invention uses temperatures below 70°C, thereby reducing energy consumption and suppressing undesirable reactions.

[0024] [Processing object] The object to be treated is a molded article containing polyethylene terephthalate as a main component, and includes a molded article to which a curable resin composition or a cured product thereof is attached.

[0025] Here, the term "main component" refers to a component that accounts for more than 50 mass % of the constituent components in the material to be treated. The term "curable resin composition" refers to a resin composition that has curability, and includes resin compositions in which a portion of the resin composition is cured and in which the curing reaction can further proceed. The term "cured product" refers to a state in which the curing reaction of the curable resin composition has substantially completed.

[0026] The molded article is typically a so-called used molded article that has been used for its intended purpose. The form of the molded article is not particularly limited, and examples thereof include fibers, films, sheets, bottles, tapes, trays, etc.

[0027] In particular, the molded article is preferably a film. When the molded article is a film, the hydrolysis reaction easily proceeds even at a low temperature of less than 70°C, and terephthalic acid can be produced efficiently. The thickness of the film is preferably 1 μm or more and 100 μm or less. It is presumed that such a thin film has a large specific surface area and a large area in contact with the monohydric alcohol, etc., and therefore the hydrolysis reaction easily proceeds.

[0028] Examples of polyalkylene terephthalate include polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate.

[0029] As a molded article containing polyalkylene terephthalate as a main component, a polyalkylene terephthalate film is preferred, and a polyethylene terephthalate film is particularly preferred.

[0030] The molded article has a curable resin composition or a cured product (hereinafter also referred to as "curable resin composition, etc.") adhered thereto. In the present invention, it is particularly advantageous to use a molded article having a curable resin composition adhered thereto.

[0031] The curable resin composition may be adhered to the entire surface of the molded article or to a part of the surface, and is preferably adhered to the surface of the molded article.

[0032] The curable resin composition is not particularly limited, and may be a thermosetting or photocurable resin composition, or may be both a thermosetting and photocurable resin composition. The thermosetting and photocurable curable resin composition includes those that are thermoset but not photocured, and those that are photocured but not thermoset. The cured product may be a cured product of a thermosetting resin composition or a cured product of a photocurable resin composition, or may be a cured product of both a thermosetting and photocurable resin composition. When the curable resin composition is attached to a molded article, it is preferable because it is expected to have the effect of preventing contamination of a reactor. From this point of view, the present invention is advantageous when a thermosetting resin composition or a thermosetting and photocurable curable resin composition is attached to a molded article.

[0033] The thermosetting resin composition is, for example, a resin composition containing a thermosetting component and may further contain a thermosetting catalyst, etc. Examples of the thermosetting component include epoxy resins, isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, polyfunctional oxetane compounds, episulfide resins, and curable silicone resins. The photocurable resin composition is, for example, a resin composition containing a photopolymerizable monomer and a photopolymerization initiator.

[0034] The curable resin composition or its cured product adhered to the molded article may be derived from a solder resist composition, such as a polyethylene terephthalate film having an attachment derived from the solder resist composition. Here, the solder resist composition is a thermosetting resin composition and may further have photocurability.

[0035] The following description will be given taking a solder resist composition as an example, but the components mentioned can also be used in curable resin compositions other than solder resist compositions.

[0036] The solder resist composition may contain a thermosetting component from the viewpoint of thermosetting properties, such as the thermosetting components described above.

[0037] Among the thermosetting components, epoxy resins are preferred, and examples thereof include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, and triphenylmethane type epoxy resins.

[0038] The solder resist composition may contain a thermal curing catalyst and the like.

[0039] In order to impart photocurability to the solder resist composition, a photopolymerizable monomer, a photopolymerization initiator, etc. may be contained. In order to impart alkaline developability to the solder resist composition, a carboxyl group-containing resin may be contained.

[0040] Examples of photopolymerizable monomers include radically polymerizable monomers having one or more unsaturated bonds such as (meth)acryloyl groups or vinyl groups, and cationically polymerizable monomers having a cyclic structure such as epoxy groups. Specific examples include (meth)acrylate monomers, urethane-modified (meth)acrylate monomers having a urethane bond, epoxy-modified (meth)acrylate monomers, and silicone-modified (meth)acrylate monomers.

[0041] Alternatively, an epoxy acrylate resin obtained by reacting acrylic acid with a polyfunctional epoxy resin such as a cresol novolac epoxy resin, or an epoxy urethane acrylate compound obtained by reacting a half urethane compound of a hydroxy acrylate such as pentaerythritol triacrylate and a diisocyanate such as isophorone diisocyanate with the hydroxyl group of the epoxy acrylate resin, may be used as the photopolymerizable monomer.

[0042] The photopolymerization initiator is used to react a photocurable resin or a photopolymerizable monomer by exposure to light. Any known photopolymerization initiator can be used. One photopolymerization initiator may be used alone, or two or more photopolymerization initiators may be used in combination.

[0043] The photopolymerization initiator may be a photoradical polymerization initiator, a photocationic polymerization initiator, or a photoanionic polymerization initiator. Typical examples include alkylphenone-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzophenone-based photopolymerization initiators, benzoin-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators. Examples of the photopolymerization initiator include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4-diethylthioxanthone, and benzophenone.

[0044] Examples of the carboxyl group-containing resin include the compounds exemplified below. (1) A carboxylic acid-containing copolymer resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with one or more other compounds having an unsaturated double bond; (2) Carboxylic acid-containing photosensitive resins obtained by adding ethylenically unsaturated groups as pendants to copolymers of unsaturated carboxylic acids such as (meth)acrylic acid and one or more other compounds having unsaturated double bonds using compounds having epoxy groups and unsaturated double bonds such as glycidyl (meth)acrylate or 3,4-epoxycyclohexylmethyl (meth)acrylate, or (meth)acrylic acid chloride, etc. (3) A photosensitive carboxylic acid-containing copolymer resin obtained by reacting a copolymer of a compound having an epoxy group and an unsaturated double bond, such as glycidyl (meth)acrylate or 3,4-epoxycyclohexylmethyl (meth)acrylate, with another compound having an unsaturated double bond, with an unsaturated carboxylic acid, such as (meth)acrylic acid, and then reacting the resulting secondary hydroxyl group with a polybasic acid anhydride. (4) A carboxylic acid-containing photosensitive resin obtained by reacting a copolymer of an acid anhydride having an unsaturated double bond, such as maleic anhydride, and another compound having an unsaturated double bond with a compound having a hydroxyl group and an unsaturated double bond, such as 2-hydroxyethyl (meth)acrylate. (5) A carboxylic acid-containing photosensitive resin obtained by reacting a polyfunctional epoxy compound with an unsaturated monocarboxylic acid and then reacting the resulting hydroxyl group with a saturated or unsaturated polybasic acid anhydride. (6) A hydroxyl group- and carboxylic acid-containing photosensitive resin obtained by reacting a hydroxyl group-containing polymer such as a polyvinyl alcohol derivative with a saturated or unsaturated polybasic acid anhydride, and then reacting the resulting carboxylic acid with a compound having an epoxy group and an unsaturated double bond in one molecule; (7) A carboxylic acid-containing photosensitive resin obtained by reacting a reaction product of a polyfunctional epoxy compound, an unsaturated monocarboxylic acid, and a compound having at least one alcoholic hydroxyl group and one reactive group other than the alcoholic hydroxyl group that reacts with an epoxy group in one molecule with a saturated or unsaturated polybasic acid anhydride; (8) A carboxylic acid-containing photosensitive resin obtained by reacting an unsaturated monocarboxylic acid with a polyfunctional oxetane compound having at least two oxetane rings in one molecule, and then reacting a saturated or unsaturated polybasic acid anhydride with the primary hydroxyl group in the resulting modified oxetane resin; and (9) A carboxylic acid-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin with an unsaturated monocarboxylic acid, followed by a polybasic acid anhydride, to obtain a carboxylic acid-containing resin, and then further reacting the resulting resin with a compound having one oxirane ring and one or more ethylenically unsaturated groups in the molecule. (10) A carboxylic acid-containing photosensitive resin obtained by reacting a polyfunctional phenolic resin with an alkylene oxide or a cyclic carbonate, reacting the resulting reaction product with a monocarboxylic acid having an unsaturated double bond, and then reacting the resulting reaction product with a saturated or unsaturated polybasic acid anhydride.

[0045] The solder resist composition may contain components other than those mentioned above, such as known flame retardants, plasticizers, lubricants, colorants (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, antiaging agents, fillers, reinforcing agents, antistatic agents, surfactants, tension modifiers, shrinkage inhibitors, flowability modifiers, surface treatment agents, etc.

[0046] A polyethylene terephthalate film having deposits derived from a solder resist composition can be produced from a dry film of solder resist used in the production process of printed wiring boards, etc. A dry film of solder resist typically comprises a layer of the solder resist composition on a polyethylene terephthalate film, and when used, the layer of the solder resist composition is placed on an object to be treated, such as a circuit board, so that it is in contact with the object to be treated, and in some cases, a portion of the layer of the solder resist composition is photocured, after which the polyethylene terephthalate film is peeled off. The peeled polyethylene terephthalate film may still have the solder resist composition or a cured product of the solder resist composition adhering to it, and such a used polyethylene terephthalate film can be used as the object to be treated.

[0047] The object to be treated may be a packaging material, a storage container, or the like made of polyalkylene terephthalate to which the curable resin composition or its cured product is attached.

[0048] The workpiece may contain polyolefins in addition to a molded article to which a curable resin composition or the like is attached. Examples of polyolefins include polyethylene, polypropylene, copolymerized polypropylene, oriented polypropylene (OPP), ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Examples of polyethylene include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and very-low-density polyethylene (VLDPE). For example, a solder resist dry film has a protective film made of polyolefin or the like on a layer made of a solder resist composition, and this protective film is peeled off before use. This peeled protective film can also be included in the workpiece.

[0049] When the material to be treated contains polyolefins, if the reaction temperature is high, the polyolefins may melt and adhere to the reactor, causing contamination of the reactor. However, since the temperature used in the production method of the present invention is relatively low, at less than 70°C, the polyolefins do not melt, and contamination of the reactor can be prevented.

[0050] The object to be treated may contain components other than the curable resin composition and polyolefins, as long as the effects of the present invention are not impaired. Examples of such components include known flame retardants, plasticizers, lubricants, colorants (pigments, dyes, etc.), UV absorbers, antioxidants, antiaging agents, fillers, reinforcing agents, antistatic agents, surfactants, tension modifiers, shrinkage inhibitors, flowability modifiers, and surface treatment agents.

[0051] [Monohydric alcohol and water] The production method of the present invention uses a monohydric alcohol and water. By using a monohydric alcohol and water together with a strong inorganic base, the material to be treated can be hydrolyzed at a low temperature.

[0052] The monohydric alcohol and water not only function as a reaction solvent for hydrolysis, but also function, together with the strong inorganic base, to cleave the bonds of the polyalkylene terephthalate contained in the material to be treated.

[0053] The monohydric alcohol is preferably a monohydric alcohol having 1 to 12 carbon atoms, more preferably a monohydric alcohol having 1 to 6 carbon atoms, and particularly preferably a monohydric alcohol having 1 to 3 carbon atoms. Examples of monohydric alcohols include methanol, ethanol, propanol, butanols such as 1-butanol, pentanol, hexanol, heptanol, and octanol, and among these, methanol, ethanol, and 1-butanol are preferred. These may be used alone or in combination of two or more in any ratio.

[0054] From the viewpoint of reactivity, the amount of monohydric alcohol used per 100 parts by mass of the material to be treated is preferably 10 parts by mass or more and 10,000 parts by mass or less, more preferably 100 parts by mass or more and 5,000 parts by mass or less, and particularly preferably 200 parts by mass or more and 1,000 parts by mass or less.

[0055] The water is not particularly limited, but is preferably ion-exchanged water.

[0056] From the viewpoint of reactivity, the amount of water used per 100 parts by mass of the material to be treated is preferably 100 parts by mass or more and 3000 parts by mass or less, more preferably 300 parts by mass or more and 2500 parts by mass or less, and even more preferably 500 parts by mass or more and 2000 parts by mass or less.

[0057] The amount of water used per 100 parts by mass of the monohydric alcohol is preferably 100 parts by mass or more and 1000 parts by mass or less, and more preferably 150 parts by mass or more and 500 parts by mass or less.

[0058] In the production method of the present invention, a solvent other than the monohydric alcohol and water may be present within a range that does not impair the effects of the present invention. However, from the viewpoint of reducing the environmental load, it is preferable that the conditions are such that no halogenated solvent is present. Furthermore, since the curable resin composition and the like contained in the object to be treated are particularly easily dissolved in halogenated solvents, if a halogenated solvent is present, the curable resin composition and the like may not be completely removed by a filtration step described later, etc., and the purity of terephthalic acid may decrease. Therefore, it is preferable that the conditions are such that no halogenated solvent is present, also from the viewpoint of avoiding a decrease in the purity of terephthalic acid.

[0059] [Strong inorganic bases] The step of hydrolyzing the material to be treated is carried out in the presence of a strong inorganic base. As used herein, "strong inorganic base" refers to an inorganic compound whose base dissociation constant (pKb) in water is 2 or less, or whose conjugate acid has an acid dissociation constant (pKa) in water of 12 or more. In the present invention, the presence of the strong inorganic base allows hydrolysis to proceed in a basic environment.

[0060] Examples of inorganic strong bases include alkali metal hydroxides and alkaline earth metals, and alkali metal hydroxides are preferred, such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. Of these, sodium hydroxide and potassium hydroxide are preferred. These may be used alone or in combination of two or more in any ratio.

[0061] From the viewpoint of reactivity, the amount of the inorganic strong base used per 100 parts by mass of the material to be treated is preferably 10 parts by mass or more and 100 parts by mass or less, and more preferably 30 parts by mass or more and 90 parts by mass or less.

[0062] The amount of the inorganic strong base used per 100 parts by mass of the monohydric alcohol is preferably 1 part by mass or more and 50 parts by mass or less, and more preferably 5 parts by mass or more and 30 parts by mass or less.

[0063] [Hydrolysis process] In the step of hydrolyzing the material to be treated, the order in which the monohydric alcohol, water, inorganic strong base, and material to be treated are charged into a reactor is not particularly limited, and they can be charged and reacted in any order. The hydrolysis step refers to the period from first charging any one of the monohydric alcohol, water, inorganic strong base, and material to be treated into a reactor, to charging all of them, and completing the preparation of terephthalic acid.

[0064] The step of hydrolyzing the material to be treated is carried out at a temperature lower than 70°C. If the temperature is lower than 70°C, the reaction of the curable resin composition contained in the material to be treated is suppressed during the production of terephthalic acid, and contamination of the reactor can be prevented. Furthermore, from the viewpoint of improving the yield of terephthalic acid, the temperature may be 0°C or higher, and is preferably 10°C or higher.

[0065] In the step of hydrolyzing the material to be treated, the pressure is not particularly limited and can be any pressure. For example, the step of hydrolyzing the material to be treated may be performed under atmospheric pressure.

[0066] In the step of hydrolyzing the material to be treated, the reaction time is not particularly limited and can be any time. For example, the step of hydrolyzing the material to be treated can be carried out for 1 to 72 hours.

[0067] The step of hydrolyzing the material to be treated is preferably carried out under conditions where the pH is 9 to 12 after adding the monohydric alcohol, water, strong inorganic base, and material to be treated.

[0068] The reactor used in the step of hydrolyzing the material to be treated is not particularly limited, and any known reactor can be used. Examples of reactors that can be used include glass flasks, screw bottles, and stainless steel reaction vessels.

[0069] In the step of hydrolyzing the material to be treated, the order in which the monohydric alcohol, water, inorganic strong base, and material to be treated are charged into the reactor is not particularly limited. For example, it is preferable to carry out the steps in the following order: charging the monohydric alcohol, inorganic strong base, and material to be treated into the reactor to obtain a mixture, and then charging water into the reactor to mix the mixture with the water.

[0070] When hydrolysis is carried out in the above order, the monohydric alcohol and the strong inorganic base are preferably used as a solution in which they are dissolved in the strong inorganic base and the monohydric alcohol. The material to be treated and this solution can be charged into a reactor, followed by water.

[0071] The solution of the strong inorganic base and the monohydric alcohol and the material to be treated can be placed in a reactor and stirred to achieve a sufficient homogeneity, at a temperature of less than 70°C, preferably 0°C or higher, more preferably 10°C or higher. The pressure during stirring is not particularly limited, and may be, for example, atmospheric pressure.

[0072] Next, water is added to the reactor and the mixture is stirred to complete the hydrolysis reaction. Stirring can be carried out for, for example, 1 to 72 hours. The temperature during this process can be set to less than 70°C, preferably 0°C or higher, and more preferably 10°C or higher. The pressure during stirring is not particularly limited, and may be, for example, atmospheric pressure.

[0073] [Optional process] The production method of the present invention includes a filtration step of filtering the product of the hydrolysis step to obtain a filtrate; The method may further include a separation step of adding an acid to the filtrate and then filtering to separate terephthalic acid.

[0074] In the filtration step, impurities such as the curable resin composition or its cured product, polyolefins, etc. can be removed. The filtration method is not particularly limited, and filtration can be performed using filter paper, a filter, a screen, etc. When filter paper is used, the type of filter paper is not particularly limited, and commercially available filter paper can be used. When a filter or screen is used, for example, one with an opening size of 0.3 mm or more and 3 mm or less can be used.

[0075] In the separation step, it is preferable to add an acid until the pH of the filtrate reaches 5 to 6. The acid is not particularly limited, and for example, hydrochloric acid, nitric acid, etc. can be used. After adding the acid, it is preferable to stir, and the stirring time can be, for example, 30 minutes to 2 hours.

[0076] The method for producing terephthalic acid of the present invention may include steps other than the above steps, as long as the effects of the present invention are not impaired.

[0077] In the method for producing terephthalic acid of the present invention, terephthalic acid can be obtained in a yield of 50% or more.

[0078] <Method for decomposing materials to be treated> Another aspect of the present invention is a method for decomposing a workpiece, including a molded article containing polyalkylene terephthalate as a main component, having a curable resin composition or a cured product thereof adhered thereto, the method comprising a hydrolysis step of hydrolyzing the workpiece in the presence of a monohydric alcohol, water, and a strong inorganic base at a temperature of less than 70°C.

[0079] For the hydrolysis step in the decomposition method, the conditions and preferred examples described above for the method for producing terephthalic acid are applied. [Example]

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0081] <Processing objects 1 and 2> · Processing object 1: Polyethylene terephthalate film with resist components attached · Processing object 2: Polyethylene terephthalate film and polypropylene film with resist components attached

[0082] (Method for producing object 1 to be processed) The protective polypropylene film was peeled off from the dry film of Taiyo Ink Mfg. Co., Ltd.'s PSR-4000, and the solder resist composition layer was laminated onto a copper-clad laminate using a vacuum laminator (CVP-600: manufactured by Nikko Materials Co., Ltd.) so that the solder resist composition layer and the copper-clad laminate surface were in contact. The laminate was then laminated in a first chamber at 80 ° C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds. The second chamber was then pressed at 100 ° C under conditions of a press pressure of 0.5 MPa and a press time of 30 seconds, after which the polyethylene terephthalate film was peeled off. The peeled polyethylene terephthalate film had a resist component attached, and this polyethylene terephthalate film was designated as the processed object 1. The thickness of the polyethylene terephthalate film was 38 μm.

[0083] (Method for producing object 2 to be processed) In the preparation of the object to be treated 1, a mixture of the polypropylene film peeled off at the time of use and the object to be treated 1 was used as the object to be treated 2.

[0084] Example 1 10 g of the material 1 cut into 1 cm square pieces was placed in a 100 mL eggplant flask equipped with a stirrer. An alkaline solution of 7.0 g of potassium hydroxide dissolved in 50 g of methanol was added to this, and the mixture was allowed to react at 25°C for 24 hours. After the reaction was completed, 150 g of ion-exchanged water was added and stirring continued until the solution became transparent. This was filtered using a circular quantitative filter paper No. 5A, and the filtrate was collected. This filtrate was transferred to a 500 mL beaker, and while stirring with a stirrer, 35% hydrochloric acid was added until the pH was in the range of 5 to 6. Stirring was continued for 30 minutes, and the product was then obtained by filtration using a circular quantitative filter paper No. 5A.

[0085] <Example 2> The same procedure as in Example 1 was carried out except that the object to be treated was changed to 2.

[0086] Example 3 The same procedure as in Example 2 was carried out except that the amount of potassium hydroxide was changed and sodium hydroxide was also used.

[0087] Example 4 The same procedure as in Example 2 was carried out except that the reaction temperature was changed to 60°C.

[0088] <Example 5> The same procedure as in Example 2 was carried out except that sodium hydroxide was used instead of potassium hydroxide.

[0089] Example 6 The same procedure as in Example 2 was carried out except that 1-butanol was used instead of methanol.

[0090] Example 7 The same procedure as in Example 2 was carried out except that a mixed liquid of methanol / water in a weight ratio of 30:20 was used instead of methanol and the reaction temperature was changed to 60°C.

[0091] <Comparative Example 1> The same procedure as in Example 2 was carried out except that ethylene glycol was used instead of methanol and the reaction temperature was 60°C.

[0092] <Comparative Example 2> The same procedure as in Example 6 was carried out except that the reaction temperature was 100°C.

[0093] <Comparative Example 3> The same procedure as in Example 2 was carried out except that the reaction temperature was 100°C.

[0094] <Evaluation method> The production methods in the examples and comparative examples were evaluated as follows.

[0095] (1) Yield The yield of terephthalic acid obtained from the theoretical amount of polyethylene terephthalate in the treated material was taken as the theoretical yield, and the yield of terephthalic acid was calculated from the ratio of the theoretical yield to the actual reaction yield (actual reaction yield / theoretical yield), and evaluated as follows. The evaluation results are shown in Table 1. A: Yield 70% or more B: Yield 50% or more but less than 70% C: Yield is 20% or more but less than 50% D: Yield less than 20%

[0096] (2) Reactor contamination After the production of terephthalic acid was completed, the reactor was visually inspected for contamination. The evaluation was as follows. The evaluation results are shown in Table 1. Good: No contamination in the reactor Bad: Reactor is contaminated - : Not checked

[0097] [Table 1]

[0098] It is clear from Table 1 that the production method of the present invention enables terephthalic acid to be produced at a low temperature with good yield, and also prevents contamination of the reactor. [Industrial Applicability]

[0099] According to the present invention, it is possible to provide a method for producing terephthalic acid, which can produce terephthalic acid in good yield from a workpiece containing polyethylene terephthalate as a main component and further containing a curable resin composition or a cured product thereof while suppressing contamination of a reactor. Furthermore, according to the present invention, it is possible to provide a method for decomposing an object to be treated, which decomposes an object to be treated containing polyethylene terephthalate as a main component and further containing a curable resin composition or a cured product thereof in a good yield while suppressing contamination of a reactor.

Claims

1. A method for producing terephthalic acid, comprising a hydrolysis step of hydrolyzing a workpiece, which includes a molded article containing polyalkylene terephthalate as a main component and having a curable resin composition or a cured product thereof adhered thereto, in the presence of a monohydric alcohol, water, and an inorganic strong base at a temperature of less than 70°C.

2. The method for producing terephthalic acid according to claim 1, wherein the molded article containing the polyalkylene terephthalate as a main component is a film.

3. The method for producing terephthalic acid according to claim 1, wherein the monohydric alcohol has from 1 to 12 carbon atoms.

4. 2. The method for producing terephthalic acid according to claim 1, wherein the strong inorganic base is an alkali metal hydroxide.

5. The method for producing terephthalic acid according to claim 1 , wherein the hydrolysis is carried out in the absence of a halogenated solvent in the hydrolysis step.

6. The method for producing terephthalic acid according to claim 1 , wherein the material to be treated further contains a polyolefin.

7. 2. The method for producing terephthalic acid according to claim 1, wherein the hydrolysis step comprises mixing the material to be treated, the monohydric alcohol, and the inorganic strong base to obtain a mixture, and then mixing the mixture with water.

8. a filtration step of filtering the product of the hydrolysis step to obtain a filtrate; 2. The method for producing terephthalic acid according to claim 1, further comprising a separation step of adding an acid to the filtrate and then filtering the filtrate to separate terephthalic acid.

9. The method for producing terephthalic acid according to claim 1 , wherein the curable resin composition or the cured product thereof is derived from a solder resist composition.

10. A method for decomposing a treated object, including a molded article containing polyalkylene terephthalate as a main component and having a curable resin composition or a cured product thereof adhered thereto, comprising a hydrolysis step of hydrolyzing the molded article in the presence of a monohydric alcohol, water, and a strong inorganic base at a temperature of less than 70°C.

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