Recycled plastic manufacturing method

Abstract

To provide a method for manufacturing a recycled plastic which enables efficient and simple material recycling from a laminate without a step of separating a base material and a printed layer, and is excellent in moldability.SOLUTION: A method for manufacturing a recycled plastic obtains a recycled plastic (B) from a laminate (A) using an extruder having a screw and a discharge part, wherein the laminate (A) has a base material layer and a printed layer, a chlorine content is 0.4 mass% or less in the total mass of the laminate (A), 80 mass% or more of a polyester resin is contained in the total mass of the laminate (A), and the method includes a step of heating and melting the laminate (A) in the extruder, and obtaining a resin composition (a), and a step of extruding the resin composition (a) from the discharge part of the extruder at a pressure of 18 MPa or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing recycled plastics, which involves recycling materials from a laminate containing a polyester resin. [Background technology]

[0002] In recent years, plastic film packaging, plastic bottles, and other plastic products have been discarded and dumped into the ocean as litter, causing environmental pollution problems. Plastic products are broken down in seawater into submicron-sized fragments (microplastics), which float in the seawater. Microplastics are ingested by marine organisms such as fish and become concentrated in their bodies. This has raised concerns about the impact on the health of seabirds and humans, who consume marine organisms as food.

[0003] Multilayer food packaging uses a variety of plastic substrates as film substrates, including polyester (PET), nylon (NY), polypropylene (PP), and polyethylene (PE). Multilayer food packaging is produced, for example, by printing a first film substrate with printing ink, laminating a second film substrate onto the printed layer, optionally via an adhesive layer, and then cutting and heat-sealing the resulting package. However, due to compatibility and other issues, multilayer food packaging containing multiple different materials is difficult to recycle.

[0004] Food packaging is usually discarded as garbage, but it can also be recycled. When recycling packaging, first, impurities contained in the packaging are removed, the packaging is crushed, and if necessary, alkali treatment is performed (Patent Document 1). The washed product is melted as a raw material and made into pellets. The obtained pellets are then processed into new products. However, with the above recycling method, most of the printed layer contained in the packaging remains without being removed, and the obtained pellets are of poor quality.

[0005] Recently, as in Patent Documents 2 and 3, technologies have been disclosed in which a primer layer or a removable printed layer is provided on a plastic substrate, and the printed pattern or laminated packaging material is then separated and removed. However, the increase in the number of processes increases the time required to complete processing and the amount of setup work that requires human intervention, which could result in a decrease in production volume. Patent Document 4 discloses a recycling method for reusing waste biaxially oriented polyester film without the step of removing the printed layer, but does not disclose any technology related to a recycling method for laminated bodies made primarily from polyester suitable for packaging materials.

[0006] In other words, there is a need for a method for producing high-quality recycled plastics that does not require a step of removing the printed layer from the laminate, but only involves simple separation, washing, and dehydration. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-19003 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-031899 [Patent Document 3] Japanese Patent Publication No. 2020-196855 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-116857 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide a method for producing recycled plastics with excellent moldability that allows for efficient and simple material recycling from laminates without the need for a process for removing the substrate and the printed layer. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above problems can be solved by using the method for producing recycled plastic described below, and have thus achieved the present invention.

[0010] That is, the present invention provides a method for producing recycled plastics, which uses an extrusion device equipped with a screw and a discharge section to obtain recycled plastic (B) from a laminate (A), The laminate (A) includes a substrate layer and a printed layer, has a chlorine content of 0.4 mass% or less based on the total mass of the laminate (A), and contains a polyester resin in an amount of 80 mass% or more based on the total mass of the laminate (A); A step of heating and melting the laminate (A) in the extrusion device to obtain a resin composition (a); and The present invention relates to a method for producing recycled plastics, which includes a step of extruding the resin composition (a) from the discharge part of an extrusion device at a pressure of 18 MPa or less.

[0011] The present invention also provides a method for producing recycled plastics, in which recycled plastic (B) is obtained from a laminate (A) using an extrusion device equipped with a screw and a discharge section, comprising: The laminate (A) includes a substrate layer and a printed layer, has a chlorine content of 0.4 mass% or less based on the total mass of the laminate (A), and contains a polyester resin in an amount of 80 mass% or more based on the total mass of the laminate (A); The present invention relates to a method for producing recycled plastics, which includes a step of heating and melting the laminate (A) at 260 to 290°C in the extrusion device to obtain a resin composition (a), and a step of extruding the resin composition (a) from the discharge part of the extrusion device.

[0012] The present invention also relates to the above-mentioned method for producing recycled plastics, which further comprises a step of dehydrating and drying the laminate (A) to remove moisture until the moisture content in the laminate (A) is 0.2 mass % or less.

[0013] The present invention also relates to the above-mentioned method for producing recycled plastics, which further comprises a water cooling step.

[0014] The present invention also relates to the above-mentioned method for producing recycled plastics, wherein the laminate (A) has an intrinsic viscosity of 0.58 to 0.75.

[0015] The present invention also relates to the method for producing recycled plastics described above, wherein the printed layer of the laminate (A) contains a pigment and a binder resin, and the chlorine content of the binder resin is 5% by mass or less.

[0016] The present invention also relates to the method for producing recycled plastics, wherein the binder resin contains a urethane resin, and the urethane resin has structural units derived from polyester polyol.

[0017] The present invention also relates to the method for producing recycled plastics described above, wherein the content of the pigment is 30 mass % or less of the total mass of the printed layer.

[0018] The present invention also relates to the method for producing recycled plastics, wherein the rotation speed of the screw provided in the extrusion device is 50 to 1000 RPM.

[0019] The present invention also relates to the above-mentioned method for producing recycled plastics, wherein the laminate (A) includes an adhesive layer, and the adhesive layer is a reaction product of a reactive urethane adhesive containing polyisocyanate and polyester polyol.

[0020] The present invention also relates to a method for producing a molded article of recycled plastic produced by the above-mentioned method for producing recycled plastic. [Effects of the Invention]

[0021] The present invention makes it possible to provide a method for producing recycled plastics with excellent moldability, which allows for efficient and simple material recycling from laminates without the need for a process for removing the substrate and the printed layer. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following describes in detail the embodiments of the present invention, but the embodiments or explanations of the requirements described are examples of the embodiments of the present invention, and the present invention is not limited to these contents as long as it does not exceed the gist of the present invention.

[0023] In the present invention, the laminate (A) may be abbreviated simply as "laminate (A)", but this has the same meaning.

[0024] (Extrusion device equipped with a screw and a discharge section) The extrusion device used in the present invention includes a screw and a discharge section. The extrusion device is a device capable of melting and molding commonly used thermoplastic resins, and a known extrusion device such as that described in JP 2017-148997 A can be used. Specifically, it has a supply port for supplying materials, a melt-kneading section for melting and kneading materials such as thermoplastic resin supplied from the supply port, and a discharge section for discharging the thermoplastic resin melted and kneaded in the melt-kneading section. The melt-kneading section is equipped with a screw, and the material is melted and kneaded by the rotation of the screw, a heat source such as an electric heater, and shear heat generated from the material itself. The molten material passes through a mesh in the discharge section and is discharged. Examples of the extrusion device include a twin-screw extruder, a single-screw extruder, and a rotor-type twin-screw kneader.

[0025] (Manufacturing method of recycled plastic (B)) The method for producing the recycled plastic (B) of the present invention preferably has the following embodiments, for example. In one embodiment, the laminate (A) is preferably in a fragmented form obtained by cutting or crushing. For fragmentation, a method such as crushing is used. Furthermore, the laminate (A) is preferably washed, and the present invention preferably includes a washing step. The laminate (A) is then processed to obtain the recycled plastic (B). The processing includes a heat-melting step and an extrusion step, which will be described in detail below.

[0026] (Crushing) Crushing is an effective way to fragment the shape of the laminate (A). The crushing method is not particularly limited, and examples thereof include methods using a jaw crusher, impact crusher, cutter mill, stamp mill, ring mill, roller mill, jet mill, or hammer mill. The size of the fragments of the laminate (A) preferably has a side length of 1 mm to 40 mm, more preferably 5 mm to 20 mm. Furthermore, to prevent a decrease in the molecular weight of the polyester, crushing is preferably carried out at a temperature of 220°C or less, more preferably 200°C or less, and even more preferably 180°C or less.

[0027] (Washing) The laminate (A) or fragmented printed matter or laminate (A) is preferably washed. Examples of washing methods include batch washing and continuous washing, and water, detergent, and neutralizing agent may be used. The washed laminate (A) is preferably thoroughly dehydrated and dried. This is because if the polyester undergoes hydrolysis due to moisture, the molecular weight decreases, which reduces viscosity during injection molding and makes it difficult to produce molded products. The moisture content in the laminate (A) or fragmented laminate (A) is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less.

[0028] (processing) The fragmented or washed laminate (A) is heated, melted, and kneaded in an extruder equipped with a screw to form a resin composition (a), which is then cooled to 40°C or below to form recycled plastic (B).

[0029] Specifically, the process for obtaining the recycled plastic (B) preferably includes the steps of feeding the laminate (A) from a feed port, melting and kneading the laminate (A) fed from the feed port to form a resin composition (a), discharging the melt-kneaded resin composition (a) in a melt-kneading section, and cooling the resin composition (a) discharged from the discharge section to form the recycled plastic (B). The shape of the recycled plastic (B) is not particularly limited, and examples include rods, particles, cubes, rectangular parallelepipeds, and amorphous shapes.

[0030] The laminate (A) is heated to a temperature of 260 to 290°C, melted, and kneaded to form the resin composition (a). The temperature range in this process must take into consideration the glass transition temperature of the laminate (A), the melting temperature, the shape of the recycled plastic, and the pressure applied during the molding process. The melting temperature is preferably 270 to 290°C. The laminate is heated to a temperature of 270 to 290°C, melted, and kneaded to form the homogeneous recycled plastic (B). The screw rotation speed during kneading is preferably 50 to 1000 RPM. Within this range, the resin composition (a) and the recycled plastic (B) can be prevented from generating foreign matter such as insoluble matter, burnt matter, and carbonized matter, as well as from hydrolysis and thermal decomposition, and the fluidity during injection molding can be made uniform. As a result, good moldability can be maintained, which is preferable.

[0031] In the step of obtaining recycled plastic (B) by extruding resin composition (a), the resin pressure at the tip discharge section of the extruder is preferably 18 MPa or less, more preferably 15 MPa, and even more preferably 10 MPa. This pressure makes it difficult for impurities to be contained, and recycled plastic (B) with stable purity can be continuously obtained. In order to remove foreign matter from the pellets being formed at the discharge section of the extrusion device, it is preferable to use a screen mesh (metal mesh). The type of screen mesh (metal mesh) is not particularly limited, and examples include woven types such as plain weave, twill weave, plain tatami weave, and twill tatami weave, and punched metal types, with plain weave being preferred. The size of the screen mesh is preferably 40 mesh or larger, more preferably 80 mesh or larger, and even more preferably 120 mesh or larger, taking into consideration the pressure at the discharge part and clogging.

[0032] The discharged resin composition (a) is cooled and shredded to obtain the recycled plastic (B) by a hot cutting method or a strand cutting method, but there is no particular limitation.

[0033] Examples of the cooling method include air cooling, wind cooling, and water cooling. The resin composition (a) is preferably cooled to 20 to 80°C, more preferably 30 to 60°C.

[0034] Furthermore, various additives may be added to the fragmented laminate (A) as needed, and then the fragmented laminate (A) may be processed in an extrusion device. The cut or crushed material and optional components may be mixed using a Henschel mixer, a tumbler, a disper, or the like.

[0035] (Additives for recycled plastics (B)) The recycled plastic (B) of the present invention may further contain known additives, etc., within the range that does not impair the effects of the present invention. Since the viscosity of polyester is easily reduced by hydrolysis, it is preferable to add a modifier. Examples of modifiers include carbodiimide compounds and acrylic compounds.

[0036] Examples of other additives include at least one antioxidant selected from the group consisting of phenolic and phosphorus-based antioxidants; at least one lubricant selected from the group consisting of fatty acid amides, alkylene fatty acid amides, metal soaps, and esters; hindered amine weather stabilizers; waxes having an acid value of 5 mgKOH / g or less; and at least one antistatic agent selected from the group consisting of fatty acid sulfonates and fatty acid esters.

[0037] (Laminated body (A)) The present invention uses a laminate (A), which includes a substrate layer and a print layer. Specific examples of the structure include, but are not limited to, the following structures. In the structure descriptions (1) to (5) below, " / " indicates the boundary between layers. The adhesive layer is not limited to those composed of adhesives used in conventionally known methods such as dry lamination and non-sol lamination, but also includes cases where the adhesive is composed of melt-soluble polyester or other extruded resins used in extrusion lamination. (1) Base material / printing layer / adhesive layer / sealant (2) Substrate / printing layer / adhesive layer / intermediate substrate layer / adhesive layer / sealant (3) Substrate / printing layer / adhesive layer / intermediate substrate layer / adhesive layer / intermediate substrate layer / adhesive layer / sealant (4) Printing layer / substrate / adhesive layer / sealant (5) Printing layer / substrate / adhesive layer / intermediate substrate layer / adhesive layer / sealant

[0038] Each of the above configurations may further include a barrier layer, preferably adjacent to the substrate, sealant, and / or print layer.

[0039] The laminate (A) contains polyester resin in an amount of 80% by mass or more of the total mass of the laminate (A). The content is more preferably 85% by mass or more, and even more preferably 90% by mass or more. When the laminate (A) contains polyester resin in the above range, a molding material having high recyclability and good moldability can be obtained.

[0040] (chlorine content) Furthermore, halogen elements that may be contained in the laminate may generate halogen gases or hydrogen chloride, an acidic gas, during pellet production, which may damage equipment or pose a risk to human health. Furthermore, the presence of hydrogen chloride and moisture may accelerate the hydrolysis of polyester, reducing its molecular weight and potentially deteriorating moldability. Furthermore, if bubbles are generated during pellet production, the pellets may be used to produce molded articles, which may result in surface irregularities and a poor surface condition. Therefore, in the printed matter or laminate (A), the chlorine content must be 0.4 mass% or less, preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less, based on the total mass of the laminate (A).

[0041] (Method for measuring chlorine content in laminate (A)) The chlorine content in the laminate (A) can be measured by a known method such as ion chromatography (IC) or an inductively coupled plasma mass spectrometer (ICP-MS). Specifically, it can be determined by a method similar to the analytical method for the chlorine content described below.

[0042] The intrinsic viscosity of the laminate (A) in the present invention is a value measured in accordance with JIS K 7367-5. The intrinsic viscosity of the laminate (A) is preferably 0.58 to 0.75, more preferably 0.60 to 0.70, and even more preferably 0.62 to 0.68. When the intrinsic viscosity of the laminate (A) is within the above range, the moldability of the recycled plastic (B) during recycling is better, which is preferable.

[0043] (base material) The substrate in the laminate (A) is preferably a plastic substrate containing polyester resin as the main raw material, and is preferably in the form of a film or sheet for use as a packaging material. Examples of the polyester substrate include polyethylene terephthalate (PET) film and polybutylene terephthalate (PBT) film. The thickness of the substrate is preferably 5 to 30 μm, more preferably 10 to 30 μm. If the thickness of the substrate is 5 μm or more, better dimensional stability, heat resistance, etc. can be obtained, and if it is 30 μm or less, better flex resistance can be obtained.

[0044] The substrate is preferably a gas barrier substrate, for example, a plastic substrate having an inorganic vapor-deposited layer of aluminum, silica, alumina, etc., or a plastic substrate having a layer containing a mixture of organic and inorganic components. Heat-sealable substrates having heat-sealability on one side are also included.

[0045] The substrate mainly containing a polyester resin may be a simple laminate of ester substrates, or may be laminated with a substrate different from the ester substrate via adhesive or the like. The "substrate different from the ester substrate" may be a film having different properties, and may be of any type. Furthermore, in the case of a laminated substrate, it may be in a form including an adhesive layer. The method for laminating plastics is not particularly limited, and examples thereof include conventionally known methods such as coextrusion, heat fusion, and pressure bonding via an adhesive layer.

[0046] The substrate preferably contains (coated or kneaded with) additives such as antistatic agents, antifogging agents, and ultraviolet protection agents, has an easily adhesive coating layer (e.g., a layer containing polyvinyl alcohol and its derivatives), or has a substrate surface that has been corona-treated or low-temperature plasma-treated. The above-mentioned additions and processing are also carried out for the purpose of improving the wettability of printing inks and other coating agents or for the purpose of imparting specific functionality to the film, and are suitably used, for example, to provide packaging that has excellent visibility of the contents by preventing fogging of the packaging material due to moisture.

[0047] (Printing layer) The printed layer in the laminate (A) can be a layer that displays any design, pattern, letter, symbol, etc. for the purpose of adding decoration or aesthetic appeal, or for the purpose of indicating the contents, expiration date, manufacturer or seller, etc. The printed layer may also be a solid printed layer that does not have any design, pattern, letter, symbol, etc. The method for forming the printed layer is not particularly limited, and the printed layer can be formed using a known colorant (pigment and / or dye), but it is preferably formed using a printing ink containing a pigment and a binder resin. The printed layer may have a single layer structure or a multi-layer structure, and may be printed on a surface layer. The thickness of the printed layer is preferably 0.1 to 6 μm, more preferably 0.5 to 4 μm, and particularly preferably 1 to 2.5 μm.

[0048] (pigment) The printed layer in the laminate (A) is preferably formed using a printing ink containing a pigment. Considering the quality degradation caused by coloring of recycled plastics, the colorant content of the total mass of the printed layer is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 23% by mass or less. The colorant is preferably a pigment, and the pigment may be any of organic pigments, inorganic pigments, and extender pigments. Preferred inorganic pigments include those containing titanium oxide, and preferred extender pigments include silica, barium sulfate, kaolin, clay, calcium carbonate, and magnesium carbonate. Preferred organic pigments are those made of organic compounds or organometallic complexes. One type of colorant such as a pigment may be used alone, or two or more types may be used in combination.

[0049] (organic pigments) Examples of the organic pigment include, but are not limited to, soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Further examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments.

[0050] The hue of the organic pigment is preferably at least one selected from the group consisting of black pigments, cyan pigments, green pigments, red pigments, purple pigments, yellow pigments, orange pigments, and brown pigments. Furthermore, at least one selected from the group consisting of black pigments, cyan pigments, red pigments, and yellow pigments is more preferred. Specific examples of organic pigments are shown by their CI numbers in the Colour Index International (CI). Preferably CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Yellow 83, CI Pigment Yellow 14, CI Pigment Orange 38, CI Pigment Orange 13, CI Pigment Yellow 180, CI Pigment Yellow 139, CI Pigment Red 185, CI Pigment Red 122, CI Pigment Red 178 , CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, CI Pigment Violet 23, CI Pigment Violet 37, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6, CI Pigment Green 7, CI Pigment Orange 34, CI Pigment Orange 64, CI Pigment Black 7.

[0051] Examples of inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, titanium oxide, and zinc oxide. Aluminum can be either leafing or non-leafing, with non-leafing being preferred.

[0052] (binder resin) The printed layer in the laminate (A) is preferably formed using a printing ink containing a binder resin, which refers to the binding resin in the printing ink and, as described below, preferably has a chlorine content of 5 mass % or less in the total binder resin.

[0053] The binder resin is preferably a thermoplastic resin soluble in an organic solvent. It is preferable to use a resin having a glass transition temperature of -60°C or higher but lower than 40°C in combination with a resin having a glass transition temperature of 40°C or higher but 200°C or lower. It is more preferable to use a resin having a glass transition temperature of -50°C to 0°C in combination with a resin having a glass transition temperature of 50°C to 190°C. In this specification, the glass transition temperature is a value measured using a differential scanning calorimeter (DSC).

[0054] Examples of binder resins include, but are not limited to, urethane resins, cellulose resins, polyamide resins, rosin resins, ethylene-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, styrene resins, dammar resins, styrene-maleic acid copolymer resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, butyral, polyacetal resins, petroleum resins, and modified resins thereof. These resins can be used alone or in combination of two or more. Among the above, it is preferable that the binder resin does not contain a vinyl chloride-vinyl acetate copolymer resin, and it is more preferable that the binder resin contains a urethane resin.

[0055] (urethane resin) The urethane resin is not particularly limited and may be produced by any known method. Suitable examples of the urethane resin include a urethane resin made of a polyester polyol and a polyisocyanate, and a urethane resin obtained by reacting a urethane prepolymer having a terminal isocyanate group made of a polyester polyol and a polyisocyanate with a polyamine.

[0056] When the printed layer in the laminate (A) contains a binder resin and the binder resin contains a urethane resin, the urethane resin preferably has a structural unit derived from a polyester polyol. The urethane resin having structural units derived from polyester polyol tends to have an intrinsic viscosity within a suitable range. The content of structural units derived from polyester polyol in the urethane resin is preferably 50% by mass or more, and more preferably 60% by mass or more. Examples of the production method include the method described in JP-A-2013-256551.

[0057] (Chlorine content of binder resin) The chlorine content of the binder resin is the content (% by mass) of chlorine atoms based on the mass of the binder resin. The binder resin in the present invention preferably has a chlorine content of 5% by mass or less, including 0% by mass. If the chlorine content is 5% by mass or less, the product will be environmentally safe and free chlorine will be less likely to be generated. The chlorine content is more preferably 4% by mass or less, even more preferably 3% by mass or less, and particularly preferably 2% by mass or less.

[0058] The chlorine content can be measured using known methods such as ion chromatography (IC) or inductively coupled plasma mass spectrometry (ICP-MS). Examples of measuring instruments include the LC-20ADsp manufactured by Shimadzu Corporation for IC and the Agilent 7700x manufactured by Agilent Technologies for ICP-MS. The chlorine content of the printed layer can be simply calculated from the chlorine content of each raw material constituting the printed layer using the following formula. The same applies to each of the other layers. Formula: Chlorine content (%) in total mass of binder resin solids = mass of chlorine in total mass of binder resin solids / total mass of binder resin solids (%) Formula: Chlorine content (%) in the total mass of solids in the printed layer = mass of chlorine in the total mass of solids in the printed layer / total mass of solids in the printed layer (%)

[0059] In the present invention, the chlorine content is preferably measured in accordance with JIS K0127 (2013), in which a sample pretreated by a combustion method is quantified by ion chromatography.

[0060] (Degree of nitrification of binder resin) The degree of nitrification is the degree of esterification of nitrate esters expressed as the nitrogen content (mass %), and for example, commercially available nitrocellulose usually has a nitrogen content of 10 to 12 mass %. The binder resin in the printed layer of the laminate (A) preferably has a nitration degree of 1% by mass or less, including the case where it is 0. When the nitration degree is 1% by mass or less, NO X Gas generation can be suppressed, and a safer recycled plastic (B) can be provided. The degree of nitration of the binder resin is more preferably 0.6% by mass or less, even more preferably 0.4% by mass or less, and particularly preferably 0.2% by mass or less. The nitration degree of the urethane resin is preferably 0.3% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0.1% by mass or less. The nitration degree of the resin (P) described below is preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and even more preferably 0.4% by mass.

[0061] (Resin (P)) The binder resin in the printed layer of the laminate (A) preferably further contains a resin (P) other than the urethane resin. The resin (P) is preferably a resin having a ring structure, more preferably a resin having at least one ring structure selected from the group consisting of an acetal ring structure, an aromatic ring structure, an alicyclic ring structure, and a pyranose ring structure, and even more preferably a resin having an acetal ring structure. These ring structures may have double bonds, or may have alkyl groups or other substituents. This is because of compatibility with the recycled plastic (B).

[0062] Resin (P) preferably contains structural units having a ring structure in the range of 40 to 95 mass %, more preferably 50 to 90 mass %, based on the mass of resin (P). When the resin (P) contains structural units having a ring structure in the above range, pigment dispersion in printing ink is promoted. In addition, the laminate (A) has excellent lamination strength and can be prevented from deteriorating over time. Furthermore, the resin (P) has excellent blocking resistance. In this specification, the mass of the monomer having a ring structure includes groups substituted on or adjacent to the ring structure, such as methyl groups and nitro groups. For example, if the resin (P) is a styrene-acrylic resin containing 50% by mass of structural units derived from α-methylstyrene and 50% by mass of structural units derived from butyl methacrylate as an acrylic monomer, the content of the ring structure is 50% by mass.

[0063] The content of the structural unit having a ring structure may be calculated by the following formula. Formula: Content of structural units having a ring structure (mass%) = Mass of monomer having a ring structure × 100 / Total mass of all monomers constituting resin (P)

[0064] Examples of resins having a ring structure include polyvinyl acetal resins, cellulose ester resins, rosin resins, polystyrene resins, polyester resins having a ring structure, acrylic resins having a ring structure, and copolymer resins thereof, more preferably at least one selected from the group consisting of polyvinyl acetal resins, cellulose ester resins, and rosin resins, and even more preferably polyvinyl acetal resins.

[0065] (Polyvinyl acetal resin) The polyvinyl acetal resin is an acetal ring formed by reacting polyvinyl alcohol with an aldehyde such as butyraldehyde and / or formaldehyde, and preferably contains vinyl alcohol units, vinyl acetate units, and an acetal ring group. The polyvinyl acetal resin preferably contains 60 to 90 mass% of acetal rings, 5 to 30 mass% of vinyl alcohol units, and 0.5 to 10 mass% of vinyl acetate units, and more preferably is a polyvinyl butyral resin having a butyral ring as the acetal ring. The weight average molecular weight of the polyvinyl acetal resin is preferably 10,000 to 100,000, more preferably 10,000 to 80,000.The glass transition point of the polyvinyl acetal resin is preferably 50 to 80°C, more preferably 60 to 75°C.

[0066] (cellulose ester resin) The cellulose ester resin is preferably a cellulose acetate alkylate resin, and for example, cellulose acetate propionate and cellulose acetate butyrate are suitably used. The cellulose ester resin preferably has an alkyl group. The alkyl group is preferably an alkyl group having 10 or less carbon atoms, and examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, and hexyl groups. The alkyl group may have a substituent. The weight average molecular weight of the cellulose ester resin is preferably 5,000 to 200,000, more preferably 10,000 to 10,000, and even more preferably 15,000 to 80,000.The glass transition point of the cellulose ester resin is preferably 120°C to 180°C, and more preferably 130 to 170°C. By using a urethane resin and a cellulose ester resin in combination, printability, blocking resistance, and the like are improved.

[0067] (rosin resin) Rosin resin refers to a substance having structural units derived from rosin acid (e.g., abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid) as the main component. Here, "main component" refers to 50% by mass or more. The rosin acid or rosin resin may be hydrogenated. The rosin resin is preferably at least one selected from the group consisting of rosin-modified phenolic resin, rosin ester resin, rosin-modified maleic acid resin, and polymerized rosin resin. The acid value of the rosin resin is preferably 350 mgKOH / g or less, more preferably 250 mgKOH / g or less, and even more preferably 150 mgKOH / g or less. In one embodiment, the acid value is preferably 100 mgKOH / g or less, and more preferably 50 mgKOH / g or less. The softening point of the rosin resin is preferably 60 to 180° C., more preferably 70 to 150° C. In this specification, the softening point is a value measured by the ring and ball method, and can be measured in accordance with JIS K2207.

[0068] (rosin ester) The rosin resin is preferably a rosin ester, which is an ester condensation resin of a low-molecular-weight polyol having a molecular weight of 1,000 or less and a rosin acid. The low-molecular-weight polyol preferably has 2 to 4 hydroxyl groups per molecule (hereinafter sometimes abbreviated as "difunctional to tetrafunctional") and a molecular weight of 50 to 500. Suitable examples of such low-molecular-weight polyols include bifunctional low-molecular-weight polyols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,10-decanediol; trifunctional low-molecular-weight polyols such as glycerin and trimethylolpropane; and tetrafunctional low-molecular-weight polyols such as erythritol and pentaerythritol. Among these, trifunctional and / or tetrafunctional low-molecular-weight polyols are preferred. The weight average molecular weight of the rosin ester is preferably 500 to 2,000, and more preferably 500 to 1,500.

[0069] (adhesive layer) The adhesive layer in the laminate (A) is not particularly limited as long as it can bond the respective layers, and suitable examples thereof include polyolefin adhesives, acrylic adhesives, and reactive urethane adhesives (including dry adhesives and non-solvent adhesives). It is preferable that the adhesive layer is a reactive urethane adhesive, which is a reaction product of polyisocyanate and polyester polyol. The method for bonding (also referred to as laminating) the printed layer and the respective layers is not particularly limited, and examples thereof include conventionally known methods such as extrusion lamination, dry lamination, and non-solvent lamination.

[0070] The reactive urethane adhesive forming the adhesive layer is preferably a two-component urethane adhesive consisting of a polyol as a base agent and a polyisocyanate as a curing agent. In this case, the adhesive layer is a reaction product of this urethane adhesive. The polyol may be any compound having two or more hydroxyl groups and may be selected from known polyols. Examples of polyols include polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyether polyols, polyester polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols. Among these, polyether polyols and / or polyester polyols are preferred. The polyol may be an acid-modified product in which some of the hydroxyl groups in the polyol have been acid-modified, or a polyol in which urethane bonds have been introduced by reacting some of the hydroxyl groups in the polyol with a diisocyanate. The polyisocyanate may be any compound having two or more isocyanate groups and may be selected from known polyisocyanates. Examples of polyisocyanates include aromatic polyisocyanates, araliphatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and modified products thereof. One polyol may be used alone, or two or more polyols may be used in combination. The same applies to polyisocyanates.

[0071] (Intermediate substrate layer) Specific examples of the intermediate substrate layer are preferably plastic substrates mainly containing polyester resin as a raw material, similar to the substrate layer, such as polyethylene terephthalate (PET) film and polybutylene terephthalate (PBT) film, and also preferred are gas barrier substrates such as plastic substrates having an inorganic vapor-deposited layer of aluminum, silica, alumina, etc., or plastic substrates having a layer of a mixture of organic and inorganic components.

[0072] (sealant) The laminate (A) may further comprise a sealant. The inner layer of the sealant comes into direct contact with the packaged item, thereby protecting the packaged item. In order to form the laminate into a bag, it is preferable that the innermost layer of the sealant has heat-sealing properties. Also included in the sealant is a substrate to which a heat-sealing agent has been applied to impart heat-sealing properties. A polyethylene terephthalate film having heat-sealing properties is preferred as a material constituting the sealant.

[0073] The thickness of the sealant is not particularly limited and is set appropriately depending on the application of the laminate and the type and properties of the packaged items, but is usually preferably 10 to 80 μm. In addition, in the case of pouches (especially retort pouches), the thickness of the sealant is preferably 20 to 60 μm.

[0074] The sealant may be, for example, a sealant having a vapor-deposited inorganic layer such as aluminum, silica, and alumina, or a layer of a mixture of organic and inorganic components.

[0075] (Intrinsic viscosity of recycled plastic (B)) The intrinsic viscosity of the polyester resin in the recycled plastic (B) is significantly affected by the thermal history of the laminate (A), such as the moisture content, molding temperature, and cooling speed. The intrinsic viscosity of the recycled plastic (B) depends on the configuration of the flexible packaging and the recycling method, but is preferably 0.50 or more, more preferably 0.56 or more, and even more preferably 0.62 or more. When the intrinsic viscosity of the recycled plastic (B) is within the above range, a material suitable for various molding processes can be provided.

[0076] (molded product) A molded article can be obtained by molding the recycled plastic (B) obtained by the present invention. The molding method is not particularly limited, and examples thereof include injection molding, extrusion molding, blow molding, and compression molding. [Example]

[0077] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % represent parts by mass and % by mass unless otherwise noted.

[0078] (Hydroxyl value) The hydroxyl value is the number of milligrams of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of a sample is acetylated, and was measured by the method described in JIS K 0070.

[0079] (acid number) The acid value is the number of milligrams of potassium hydroxide required to neutralize the free fatty acids, resin acids, etc. contained in 1 g of sample, and was measured by the method described in JIS K 0070.

[0080] (amine value) The amine value is the equivalent amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of sample. The amount of potassium hydroxide is measured in mg in accordance with JIS K 0070. Specifically, 0.5 to 2 g of sample was precisely weighed (sample solid content: Sg). 50 mL of a 60 / 40 (mass ratio) mixed solution of methanol and methyl ethyl ketone was added to dissolve the precisely weighed sample. Bromophenol blue was added to the resulting solution as an indicator, and the resulting solution was titrated with 0.2 mol / L ethanolic hydrochloric acid solution (titer: f). The point at which the color of the solution changed from green to yellow was set as the endpoint, and the titer (A mL) at this point was used to calculate the amine value according to the following formula. (Formula) Amine value = (A × f × 0.2 × 56.108) / S [mgKOH / g]

[0081] (Weight average molecular weight) The weight average molecular weight was determined by measuring the molecular weight distribution using a gel permeation chromatography (GPC) device (HLC-8220 manufactured by Tosoh Corporation) and calculating the molecular weight converted using polystyrene as a standard substance. The measurement conditions are shown below. Columns: The following columns were used in series. Tosoh Corporation TSKgel Super AW2500 Tosoh Corporation TSKgel Super AW3000 Tosoh Corporation TSKgel Super AW4000 Tosoh Corporation's TSK gelguard column Super AWH Detector: RI (differential refractometer) Measurement conditions: Column temperature 40°C Eluent: tetrahydrofuran Flow rate: 1.0mL / min

[0082] (glass transition temperature (Tg)) The glass transition temperature was determined by differential scanning calorimetry (DSC). Measurements were performed using a Rigaku DSC8231 at a temperature range of -70 to 250°C and a heating rate of 10°C / min. The midpoint (inflection point) of the baseline shift due to the glass transition in the DSC curve was taken as the glass transition temperature.

[0083] (Chlorine content) The chlorine content was measured in accordance with JIS K0127 (2013). Specifically, ink or binder resin was applied to a transparent substrate to a thickness of 2.0 μm to form a coating film. The film was dried at 80°C and 0.5 g was scraped off. The scraped coating film was pretreated by the combustion method, and the chlorine content of the obtained sample was quantified by ion chromatography to determine the chlorine content.

[0084] (Measurement of intrinsic viscosity) The intrinsic viscosity was measured in accordance with JIS K 7367-5. The intrinsic viscosity was determined by dissolving 0.1 g, 0.3 g, and 0.5 g of the laminate (A) in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50 / 50 (weight ratio), removing the solid content by centrifugation, and measuring the viscosity of each solution at 30°C according to a standard method. The intrinsic viscosity of the laminate (A) was measured after crushing the laminate (A) so that the side length was 5 mm to 10 mm.

[0085] (Method for measuring moisture content of laminate (A)) The moisture content of the dried pulverized product of the laminate (A) was measured in accordance with JIS K 0068 (2001). The measuring instruments and reagents used are shown below. Measuring equipment: Karl Fischer moisture analyzer MKC-710D (Kyoto Electronics Manufacturing Co., Ltd.) : Moisture vaporizer ADP-611 (Kyoto Electronics Manufacturing Co., Ltd.) Karl Fischer reagent: Chem-Aqua Water Standard 1 (Kyoto Electronics Manufacturing Co., Ltd.)

[0086] <Synthesis of urethane resin> (Synthesis Example 1) Urethane Resin PU1 100 parts of a polyester polyol (hereinafter referred to as "MPD / SA") having a number average molecular weight of 2,000, which is a condensation product of 3-methyl-1,5-pentanediol (MPD) and sebacic acid (SA), 1 part of 1,4-butanediol (hereinafter referred to as "1,4-BD"), 28.5 parts of isophorone diisocyanate (hereinafter referred to as "IPDI"), and 32.1 parts of ethyl acetate were mixed and reacted at 90°C for 5 hours in a nitrogen atmosphere to obtain a urethane prepolymer with a terminal isocyanate. Next, 11.0 parts of isophoronediamine (hereinafter referred to as "IPDA"), 1.0 part of N-(2-aminoethyl)ethanolamine (hereinafter referred to as "AEA"), 1.0 part of dibutylamine (hereinafter referred to as "DBA"), and 300.0 parts of mixed solvent 1 (ethyl acetate / isopropanol = 70 / 30 (mass ratio)) were stirred and mixed, and the obtained urethane prepolymer with terminal isocyanate was gradually added at 40°C. The mixture was allowed to react at 80°C for 1 hour to obtain a solution of urethane resin PU1 with a solid content of 30% by mass, an amine value of 6.5 mg KOH / g, a hydroxyl value of 3.8 mg KOH / g, and a weight-average molecular weight of 50,000. The chlorine content of urethane resin PU1 was 0% by mass. Furthermore, in urethane resin PU1, structural units derived from polyester polyol accounted for 70% by mass.

[0087] (Synthesis Example 2) Urethane Resin PU2 30 parts of polyester polyol having a number average molecular weight of 2,000, which is a condensate of 3-methyl-1,5-pentanediol (MPD) and sebacic acid (SA), 70 parts of polypropylene glycol (PPG1000) having a number average molecular weight of 1,000, 3 parts of 1,4-butanediol, 42.0 parts of isophorone diisocyanate, and 35.5 parts of ethyl acetate were mixed and reacted at 90°C for 5 hours in a nitrogen atmosphere to obtain a urethane prepolymer with a terminal isocyanate. Next, 16.0 parts of isophoronediamine, 1.0 part of N-(2-aminoethyl)ethanolamine, 1.0 part of dibutylamine, and 338.0 parts of mixed solvent 1 (ethyl acetate / isopropanol = 70 / 30 (mass ratio)) were stirred and mixed, and the obtained urethane prepolymer with terminal isocyanate was gradually added at 40°C. The mixture was allowed to react at 80°C for 1 hour to obtain a solution of urethane resin PU2 with a solids content of 30% by mass, an amine value of 5.2 mg KOH / g, a hydroxyl value of 3.3 mg KOH / g, and a weight-average molecular weight of 40,000. The chlorine content of urethane resin PU2 was 0% by mass. Furthermore, in urethane resin PU2, structural units derived from polyester polyol accounted for 18% by mass.

[0088] In the ink preparation examples below, the following materials were used: PVB solution: A 30% solids solution of polyvinyl butyral resin (glass transition temperature 70°C, weight average molecular weight 50,000, chlorine content 0% by mass, degree of nitration 0% by mass) containing vinyl alcohol units, vinyl acetate units, and vinyl butyral units and containing 73% by mass of butyral ring groups, in a 1 / 1 ethyl acetate / isopropanol mixed solvent. Vinyl chloride-vinyl acetate solution: 30% solids solution of vinyl chloride-vinyl acetate copolymer resin (Nissin Chemical Co., Ltd., Solbin TA3, chlorine content 47.1% by mass, nitrification degree 0% by mass) in ethyl acetate

[0089] <Ink preparation> [Gravure ink preparation example 1] Gravure ink X1 40 parts of urethane resin PU1 solution, 15 parts of polyvinyl butyral resin (PVB) solution, 5 parts of CI pigment blue 15:3 (manufactured by Toyocolor Co., Ltd., product name: LIONOL BLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 0.8 parts of ethanol (1 / g) and 36 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed for 20 minutes using a bead mill to obtain a pigment dispersion. The obtained pigment dispersion was mixed with 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water and stirred to obtain organic solvent-based gravure ink X1.

[0090] [Gravure Ink Preparation Example 2] Gravure Ink X2 40 parts of urethane resin PU1 solution, 10 parts of polyvinyl butyral resin (PVB) solution, 10 parts of CI pigment blue 15:3 (manufactured by Toyocolor Co., Ltd., product name: LIONOL BLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), 10 parts of silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 20.8 parts of ethanol (1 / g) and 36 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed for 20 minutes using a bead mill to obtain a pigment dispersion. The obtained pigment dispersion was mixed with 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water and stirred to obtain organic solvent-based gravure ink X2.

[0091] [Gravure Ink Preparation Example 3] Gravure Ink X3 40 parts of urethane resin PU1 solution, 8 parts of polyvinyl butyral resin (PVB) solution, 2 parts of vinyl chloride-vinyl acetate solution (PVC) solution, 10 parts of CI Pigment Yellow 14 (chlorine content 10.8% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 0.8 parts of ethanol (1 / g) and 36 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed for 20 minutes using a bead mill to obtain a pigment dispersion. The obtained pigment dispersion was mixed with 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water and stirred to obtain organic solvent-based gravure ink X3.

[0092] [Gravure Ink Preparation Example 4] Gravure Ink X4 40 parts of urethane resin PU2 solution, 15 parts of polyvinyl butyral resin (PVB) solution, 5 parts of CI pigment blue 15:3 (manufactured by Toyocolor Co., Ltd., product name: LIONOL BLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 0.8 parts of ethanol (1 / g) and 36 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed in a bead mill for 20 minutes to obtain a pigment dispersion. The obtained pigment dispersion was mixed with 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water and stirred to obtain organic solvent-based gravure ink X4.

[0093] [Gravure ink adjustment example 5] Gravure ink Y1 35 parts of urethane resin PU1 solution, 20 parts of vinyl chloride-vinyl acetate (PVC) solution, 5 parts of CI pigment blue 15:3 (manufactured by Toyocolor Co., Ltd., product name: LIONOL BLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 A pigment dispersion was obtained by mixing 0.8 parts of ethanol (1 / g) and 36 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) and dispersing for 20 minutes using a bead mill. The resulting pigment dispersion was mixed with 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water and stirred to obtain organic solvent-based gravure ink Y1.

[0094] <Production of Laminate (A)> (Production of Laminate (A) 1) Laminate A1 Gravure ink X1 was diluted with an ethyl acetate / isopropyl alcohol mixed solvent (70 / 30 by mass) to a Zahn cup #3 (manufactured by Rigo Co., Ltd.) for 15 seconds (25°C). It was then printed in this order onto a single-sided corona-treated polyethylene terephthalate (PET) film (thickness 12 μm) using a gravure printing machine equipped with a 35 μm deep gravure plate, and dried at 50°C to obtain a PET substrate / printed layer. Next, using a dry laminator, an adhesive (Toyo-Morton "TM-570V / CAT-RT37") was applied to the printed layer of this laminate, dried at 80°C, and a heat-sealable polyethylene terephthalate (PET) film (thickness 30 μm) was laminated on top at a line speed of 40 m / min and kept at 40°C for 3 days to obtain a laminate A1 consisting of a PET substrate / printed layer / adhesive layer / PET substrate. The coating amount of the printed layer and adhesive layer after drying was 2.5 g / m. 2 It was decided.

[0095] (Production of Laminate (A) 2) Laminate A2 A laminate A2 having a structure of PET substrate / printing layer / adhesive layer / PET substrate was obtained in the same manner as in the production process of laminate A1, except that gravure ink X1 was changed to gravure ink X2.

[0096] (Production of Laminate (A) 3) Laminate A3 A laminate A3 having a PET substrate / printing layer / adhesive layer / PET substrate structure was obtained in the same manner as in the production process of the laminate A1, except that the gravure ink X1 was changed to the gravure ink X3.

[0097] (Production of Laminate (A) 4) Laminate A4 A laminate A4 having a PET substrate / printing layer / adhesive layer / PET substrate structure was obtained in the same manner as in the production process of the laminate A1, except that the gravure ink X1 was changed to the gravure ink X4.

[0098] (Production of Laminate (A) 5) Laminate A5 Laminate A5 having a PET substrate / printed layer / adhesive layer / PET substrate structure was obtained using the same manufacturing process as laminate A1, except that the adhesive was changed to "TM-340V / CAT-29B" manufactured by Toyo-Morton Co., Ltd. and the heat retention conditions were changed to 40°C for 1 day.

[0099] (Production of Laminate (A) 6) Laminate A6 A PET substrate / printed layer was obtained using the same procedure as the printing process in the manufacturing process of laminate A1. Next, using a nonsol laminator, an adhesive ("EA-N373 A / B" manufactured by Toyo-Morton) was applied to the printed layer of this laminate, and a heat-sealable polyethylene terephthalate (PET) film (thickness 30 μm) was laminated on top of this at a line speed of 40 m / min. The film was then kept at 40 ° C for 1 day to obtain laminate A6, which had a PET substrate / printed layer / adhesive layer / PET substrate structure. The coating amount of the adhesive layer after drying was 2.0 g / m 2 It was decided.

[0100] (Production of Laminate (A) 7) Laminate A7 Laminate A7, which had a PET substrate / printed layer / adhesive layer / PET substrate structure, was obtained using the same manufacturing process as laminate A1, except that the substrate was changed to one-sided corona-treated polyethylene terephthalate (PET) (thickness 25 μm).

[0101] (Production of Laminate (A) 8) Laminate A8 Laminate A8 having a matte PET substrate / printing layer / adhesive layer / PET substrate structure was obtained using the same manufacturing process as laminate A1, except that the substrate was changed to a matte polyethylene terephthalate (matte PET) (thickness 12 μm).

[0102] (Production of Laminate (A) 9) Laminate A9 Laminate A9 was obtained in the same manner as laminate A1, except that the substrate was changed to a transparent vapor-deposited polyethylene terephthalate (GLPET, manufactured by Toppan Printing Co., Ltd.) film (thickness: 12 μm). Printing was performed on the transparent vapor-deposited surface.

[0103] (Production of Laminate (A) 10) Laminate A10 A PET substrate / printed layer was obtained using the same procedure as the printing process in the manufacturing process of Laminate A1. Next, using a dry laminator, an adhesive ("TM-570V / CAT-RT37" manufactured by Toyo-Morton) was applied to the printed layer of this laminate and dried at 80°C. The aluminum vapor-deposited surface of an aluminum vapor-deposited polyethylene terephthalate (VMPET) film (thickness 12 μm) was then laminated onto this at a line speed of 40 m / min, resulting in a PET substrate / printed layer / adhesive layer / VMPET substrate configuration. Next, the same adhesive was similarly applied to the PET surface of the VMPET substrate, dried, and a heat-sealable polyethylene terephthalate (PET) film (thickness 30 μm) was laminated to obtain Laminate A10, which consisted of a PET substrate / printed layer / adhesive layer / VMPET substrate / adhesive layer / PET substrate. The coating amount of each adhesive layer after drying was 2.5 g / m. 2 It was decided.

[0104] (Production of Laminate (A) 11) Laminate A11 Except for changing the intermediate substrate to a transparent vapor-deposited polyethylene terephthalate (GLPET manufactured by Toppan Printing Co., Ltd.) film (thickness 12 μm), the same manufacturing process as for laminate A1 was used to obtain laminate A11 having a structure of PET substrate / printing layer / adhesive layer / GLPET substrate / adhesive layer / PET substrate.

[0105] (Production of Laminate (A) 12) Laminate A12 A PET substrate / printed layer was obtained using the same procedure as the printing process in the manufacturing process of Laminate A1. Next, using a dry laminator, an adhesive ("TM-570V / CAT-RT37" manufactured by Toyo-Morton) was applied to the printed layer of this laminate and dried at 80°C. The VM side of an aluminum-deposited polyethylene terephthalate (VMPET) film (thickness 12 μm) was then laminated onto this at a line speed of 40 m / min, resulting in a PET substrate / printed layer / adhesive layer / VMPET substrate structure. Next, a heat-sealing agent ("TM-4813" manufactured by Toyo-Morton) was similarly applied to the PET side of the VMPET substrate and dried at 80°C, resulting in Laminate A12, which was a PET substrate / printed layer / adhesive layer / VMPET substrate / heat-sealing agent. The coating amount of the adhesive layer and heat-sealing agent layer after drying was 2.5 g / m. 2 It was decided.

[0106] (Production of Laminate (A) 13) Laminate A13 The substrate was changed to a double-sided corona-treated polyethylene terephthalate (PET) film (thickness 12 μm), and a PET substrate / printed layer was obtained using the same procedure as the printing process in the manufacturing process of Laminate A1. Next, using a dry laminator, an adhesive ("TM-570V / CAT-RT37" manufactured by Toyo-Morton) was applied to the PET substrate surface of this laminate, dried at 80 ° C., and then a heat-sealable polyethylene terephthalate (PET) film (thickness 30 μm) was laminated on top at a line speed of 40 m / min and kept at 40 ° C. for 3 days to obtain Laminate A13, which has a printed layer / PET substrate / adhesive layer / PET substrate configuration. The coating amount of the adhesive layer after drying was 2.5 g / m 2 It was decided.

[0107] (Production of Laminate (A) 14) Laminate S1 A laminate S1 having a structure of PET substrate / printing layer / adhesive layer / PET substrate was obtained in the same manner as in the production process of laminate A1, except that gravure ink X1 was changed to gravure ink Y1.

[0108] (Production of Laminate (A) 15) Laminate S2 Laminate S2 having a PET substrate / printing layer / adhesive layer / CPP substrate structure was obtained using the same manufacturing process as laminate A1, except that the substrate was changed to a polyethylene terephthalate (PET) film (thickness 25 μm) and the sealant substrate was changed to a unstretched polypropylene (CPP) film.

[0109] <Production of recycled plastic (B)> (Example 1) Recycled Plastic B1 The laminate A1 was cut into pieces measuring 2 cm x 2 cm and washed with water. The pulverized material was dried at 120°C for 4 hours to remove moisture until the moisture content reached 0.05% by mass, yielding a dried product. The pulverized material was placed in a single-screw extruder, melted and kneaded at a screw rotation speed of 250 rpm and 280°C, yielding a resin composition. Next, the material was extruded from the discharge port of the extrusion device using a 150-mesh filter at a pressure of 4 MPa. The material was then immediately cut using a pelletizer and immersed in cold water to cool. In this way, pellets B1, which are recycled plastic (B) recycled from the laminate A1, were obtained.

[0110] (Examples 2 to 17) Recycled Plastics B2 to B17 Pellets B2 to B17, which are recycled plastics recycled from the laminate, were obtained in the manufacturing process of recycled plastic B1 according to the conditions in Table 1. For recycled plastic B17, a modifier, polycarbodiimide ("Carbodilite LA1" manufactured by Nisshinbo Chemical Inc.), was added when the pulverized material was fed into the single-screw extruder.

[0111] (Comparative Examples 1 to 3) Recycled Plastics B18 to B20 According to the conditions in Table 1, pellets B18 to B20, which are recycled plastics recycled from the laminate in the manufacturing process of recycled plastic B1, were obtained.

[0112] <Measurement of intrinsic viscosity of recycled plastic B> The intrinsic viscosity of each of the recycled plastic B1 to B20 pellets was measured in accordance with JIS K 7367-5. The intrinsic viscosity was determined by dissolving 0.1 g, 0.3 g, and 0.5 g of recycled plastic B pellets in 100 ml of a 50 / 50 (weight ratio) phenol / tetrachloroethane mixed solvent, removing the solids by centrifugation, and then measuring the viscosity of each solution at 30°C according to a standard method. The evaluation results are shown in Table 1. A (Good): 0.62 or higher B (Acceptable): 0.56 or more to less than 0.62 C (Acceptable): 0.50 or more to less than 0.56 D (bad): less than 0.50

[0113] <Appearance of film molded body> Pellets of recycled plastics B1 to B20 were each extrusion molded at 280°C using a T-die extruder to produce a film-like molded product with a thickness of 50 μm. The number of visually identifiable foreign objects and bubbles per 0.5 m2 of the resulting film was counted and evaluated according to the following criteria. Note that recycled plastic B20 could not be molded because it was unable to obtain the melt viscosity required for molding. The evaluation results are shown in Table 1. A (Good): Foreign matter, number of shots less than 50, B (Acceptable): Foreign objects, number of shots fired: 50 or more but less than 100 C (Acceptable): Foreign objects, number of shots: 100 or more but less than 200 D (Poor): More than 200 foreign objects or shots.

[0114] [Table 1]

[0115] These results demonstrate that molded articles made from recycled plastics obtained by the manufacturing method of the present invention can provide high-quality recycled products with little or no foreign matter or foaming. It is believed that the chlorine content in the laminate of 0.4% by mass or less suppresses the amount of bubbles in the recycled plastic pellets, thereby reducing the moisture content after cooling. Furthermore, it is believed that the suppression of polyester hydrolysis due to moisture and hydrogen chloride allowed the molded articles to maintain a high molecular weight. Furthermore, by selecting the type of substrate for the laminate (A), controlling the heating and melting temperature, and the resin pressure at the tip discharge section of the extrusion device, it is presumed that the generation of foreign matter such as insoluble matter, burnt matter, and carbonized matter is suppressed, the decrease in molecular weight due to hydrolysis and thermal decomposition is suppressed, and the fluidity during injection molding is made uniform.

Claims

1. A method for producing recycled plastics, comprising the steps of: obtaining recycled plastic (B) from a laminate (A) using an extrusion device equipped with a screw and a discharge section; The laminate (A) includes a substrate layer and a printed layer, has a chlorine content of 0.4 mass% or less based on the total mass of the laminate (A), and contains a polyester resin in an amount of 80 mass% or more based on the total mass of the laminate (A); A step of heating and melting the laminate (A) in the extrusion device to obtain a resin composition (a); and A method for producing recycled plastic, comprising the step of extruding the resin composition (a) from the discharge portion of an extrusion device at a pressure of 18 MPa or less.

2. A method for producing recycled plastics, comprising the steps of: obtaining recycled plastic (B) from a laminate (A) using an extrusion device equipped with a screw and a discharge section; The laminate (A) includes a substrate layer and a printed layer, has a chlorine content of 0.4 mass% or less based on the total mass of the laminate (A), and contains a polyester resin in an amount of 80 mass% or more based on the total mass of the laminate (A); A method for producing recycled plastic, comprising: a step of heating and melting the laminate (A) at 260 to 290°C in the extrusion device to obtain a resin composition (a); and a step of extruding the resin composition (a) from a discharge portion of the extrusion device.

3. The method for producing recycled plastic according to claim 1 or 2, further comprising a step of removing moisture by dehydrating and drying the laminate (A) until the moisture content in the laminate (A) is 0.2 mass% or less.

4. The recycled plastic manufacturing method according to any one of claims 1 to 3, further comprising a water cooling step.

5. The method for producing recycled plastic according to any one of claims 1 to 4, wherein the intrinsic viscosity of the laminate (A) is 0.58 to 0.

75.

6. The method for producing recycled plastic according to any one of claims 1 to 5, wherein the printed layer of the laminate (A) contains a pigment and a binder resin, and the chlorine content of the binder resin is 5% by mass or less.

7. 7. The method for producing recycled plastic according to claim 6, wherein the binder resin contains a urethane resin, and the urethane resin has structural units derived from polyester polyol.

8. The method for producing recycled plastic according to claim 6 or 7, wherein the content of the pigment is 30 mass% or less of the total mass of the printed layer.

9. The method for producing recycled plastic according to any one of claims 1 to 8, wherein the rotation speed of the screw provided in the extrusion device is 50 to 1000 RPM.

10. The method for producing recycled plastic according to any one of claims 1 to 9, wherein the laminate (A) includes an adhesive layer, and the adhesive layer is a reaction product of a reactive urethane adhesive containing polyisocyanate and polyester polyol.

11. A method for producing a molded article of recycled plastic, produced by the method for producing recycled plastic according to any one of claims 1 to 10.

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