Two-component curable adhesive, laminate, packaging material, method for recycling laminate, recycled pellet, and molded article

Abstract

Provided is a solvent-free adhesive suitable for producing high-quality recycled plastics with little discoloration. The present invention provides a solvent-free two-component curable adhesive that contains a polyol composition (X) containing a polyol compound (A), and a polyisocyanate composition (Y) containing a polyisocyanate compound (C), wherein: the polyol compound (A) includes a polyol compound (A1) that has a hydroxyl value of 45-600 mgKOH / g and an average number of functional groups of 1.8-3.0; the polyisocyanate compound (C) includes a polyether polyurethane polyisocyanate (C1); and the polyol composition (X) and the polyisocyanate composition (Y) are used so that the urethane bond concentration becomes 2.0 mmol / g or greater after reaction.

Description

Two-component curing adhesives, laminates, packaging materials, methods for recycling laminates, recycled pellets, molded products

[0001] The present invention relates to a two-component curing adhesive, a laminate, a packaging material, a method for recycling a laminate, recycled pellets produced by the recycling method, and a molded article produced using the recycled pellets.

[0002] Laminates used in various packaging materials and labels are given aesthetic appeal, functionality, preservation properties, convenience, and transportability by laminating various types of base materials such as plastic films, metal foils, and paper. Packaging materials formed by molding these laminates into bags are used as packaging materials for food, pharmaceuticals, detergents, and other products.

[0003] Traditionally, laminates used in packaging materials have been mainly obtained by a dry lamination method, in which an adhesive dissolved in a volatile organic solvent (sometimes called a solvent-type laminate adhesive) is applied to a substrate, the organic solvent is evaporated as the laminate passes through an oven, and another substrate is bonded to it. However, in recent years, from the viewpoint of reducing environmental impact and improving the working environment, there has been a growing demand for reactive two-component laminate adhesives that do not contain volatile organic solvents (hereinafter referred to as solvent-free adhesives) (Patent Document 1).

[0004] Furthermore, in recent years, environmental pollution caused by the disposal and dumping of plastic products has become a serious concern, and there is a growing demand for the recycling of plastic products. As a result, research is underway on the material recycling of laminated materials such as food packaging. For example, Patent Document 1 discloses a method in which impurities contained in the package are removed, the package is crushed, and after alkaline treatment or other necessary processes are performed, the materials are separated and recovered according to their specific gravity, and then the raw materials are melted to form pellets. Patent Document 2 discloses a method for manufacturing recycled plastic in which the laminate is melted and kneaded without performing a step to separate or detach layers other than the plastic substrate, such as the adhesive layer.

[0005] Japanese Patent Publication No. 2014-159548 Japanese Patent Publication No. 2014-019003 Japanese Patent Publication No. 7425948

[0006] We have found that when laminates are melt-kneaded without a process to separate or detach the adhesive layer, the resulting recycled plastic may turn yellow to brown due to discoloration of the adhesive layer. Discolored recycled plastic is unsuitable for reuse. Furthermore, when manufacturing new molded products, such as plastic films, using the resulting recycled plastic, visible foreign matter may be generated, highlighting the need for an adhesive that is less prone to such defects.

[0007] This invention has been made in view of these circumstances, and aims to provide a solvent-free adhesive suitable for the production of high-quality recycled plastics with minimal discoloration, a laminate manufactured using the adhesive and suitable for the production of high-quality recycled plastics, a packaging material, a method for obtaining the recycled plastics, recycled plastics obtained by the method, and molded articles made from recycled plastics.

[0008] The present invention relates to a solvent-free, two-component curing adhesive comprising a polyol composition (X) containing a polyol compound (A) and a polyisocyanate composition (Y) containing a polyisocyanate compound (C), wherein the polyol compound (A) includes a polyol compound (A1) having a hydroxyl value of 45 mg KOH / g or more and 600 mg KOH / g or less and an average number of functional groups of 1.8 or more and 3.0 or less, and the polyisocyanate compound (C) includes a polyether polyurethane polyisocyanate (C1), and the polyol composition (X) and the polyisocyanate composition (Y) are used such that the urethane bond concentration after reaction is 2.0 mmol / g or more.

[0009] According to the present invention, it is possible to provide a solvent-free adhesive suitable for producing high-quality recycled plastics with minimal discoloration, a laminate produced using the adhesive and suitable for producing high-quality recycled plastics, a packaging material, a method for obtaining the recycled plastics, recycled plastics obtained by the method, and molded articles made from recycled plastics.

[0010] <Adhesive> The adhesive of the present invention is a two-component curing type adhesive comprising a polyol composition and a polyisocyanate composition. The adhesive of the present invention will be described in detail below.

[0011] (Polyol composition (X)) The polyol composition contains a polyol compound (A), and polyol compound (A) contains polyol compound (A1). Examples of polyol compound (A1) include polyester polyols, polyether polyols, vegetable oil polyols, polyurethane polyols, sugar alcohols, etc., and can be used alone or in combination of two or more. Polyether polyols and polyester polyols are preferably used.

[0012] Examples of polyester polyols include polyester polyols obtained as reaction products of polyhydric alcohols and polycarboxylic acids, and lactone-based polyester polyols obtained by polycondensation reactions of aliphatic polyols with various lactones such as ε-caprolactone. It is preferable to use polyester polyols obtained as reaction products of polyhydric alcohols and polycarboxylic acids.

[0013] Examples of polyhydric alcohols include aliphatic diols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohesane, and 2,2,4-trimethyl-1,3-pentanediol;

[0014] Trimethylolethane, trimethylolpropane, glycerin, hexanetriol, pentaerythritol, and other trifunctional or more aliphatic polyols;

[0015] Bisphenols such as bisphenol A and bisphenol F; alkylene oxide adducts of bisphenols obtained by adding ethylene oxide, propylene oxide, etc. to bisphenols such as bisphenol A and bisphenol F;

[0016] Examples include polyether polyols obtained by ring-opening polymerization of aliphatic diols or polyols with various cyclic ether-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether, and these can be used individually or in combination of two or more.

[0017] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, 1,3-cyclopentanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid; and anhydrides or ester-forming derivatives of these aliphatic or dicarboxylic acids; and polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acids, which can be used individually or in combination of two or more.

[0018] Examples of polyether polyols include those obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene in the presence of a polymerization initiator.

[0019] Polymerization initiators include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and triethylene glycol;

[0020] Trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol, and triol compounds of polypropylene glycol;

[0021] Examples include primary or secondary alkylamines such as ethylamine and diethylamine, amine compounds having multiple amino groups such as methylenediamine and ethylenediamine, and amine compounds having active hydrogen groups such as primary or secondary alkanolamines such as monoethanolamine and diethanolamine.

[0022] Examples of vegetable oil polyols include castor oil, dehydrated castor oil, hydrogenated castor oil (a hydrogenated product of castor oil), and castor oil alkylene oxide adducts of 5 to 50 moles.

[0023] Polyurethane polyols are reaction products of low-molecular-weight or high-molecular-weight polyols and polyisocyanate compounds. As the low-molecular-weight or high-molecular-weight polyol, the same polyhydric alcohols exemplified as raw materials for polyester polyols can be used. As the polyisocyanate compound, the same polyisocyanates that may be included in the isocyanate compositions described later can be used.

[0024] Examples of sugar alcohols include pentaerythritol, sucrose, xylitol, sorbitol, isomalt, lactitol, maltitol, and mannitol.

[0025] The polyol compound (A1) has a hydroxyl value of 45 mg KOH / g or more and 600 mg KOH / g or less, and an average functionality of 1.8 or more and 3.0 or less. Thereby, it can be made into a solventless adhesive suitable for manufacturing recycled plastics with less discoloration and high quality.

[0026] The proportion of the polyol compound (A1) in the polyol compound (A) is preferably 90% by mass or more, and more preferably 95% by mass or more. The entire amount of the polyol compound (A) may be the polyol compound (A1).

[0027] The molecular weight of the polyol compound (A1) is preferably 150 g / mol or more and 2500 g / mol or less. The molecular weight of the polyol compound (A1) can be calculated from the hydroxyl value of the polyol compound (A1) and the average functionality. The hydroxyl value can be measured by the method described in JIS-K0070.

[0028] The polyol compound (A) may further contain a polyol compound (A2) having a molecular weight of less than 150 g / mol. Examples of the polyol compound (A2) include aliphatic diols and aliphatic polyols exemplified as raw materials for polyester polyols (an example of the polyol compound (A1)), polyether polyols, and the like. The proportion of the polyol compound (A2) in the polyol compound (A) is preferably 10% by mass or less, and more preferably 5% by mass or less. The polyol compound (A) may not contain the polyol compound (A2).

[0029] The polyol compound (A) may further contain a polyol compound (A3) having a hydroxyl value of less than 45 mg KOH / g. As the polyol compound (A3), the same ones as the polyol compound (A1) can be used except that the hydroxyl value is different. The proportion of the polyol compound (A3) in the polyol compound (A) is preferably 10% by mass or less, and more preferably 5% by mass or less. The polyol compound (A) may not contain the polyol compound (A3).

[0030] The polyol composition may also preferably contain a non-aromatic amine compound (B) having one or more amino groups. In this specification, an amino group is defined as NH ２ This refers to a group or an NHR group (where R is an alkyl or aryl group which may have a functional group).

[0031] As the amine compound (B), any known compound can be used without particular limitation, including methylenediamine, ethylenediamine, isophoronediamine, 3,9-dipropanamine-2,4,8,10-tetraoxaspirodoundecane, lysine, 2,2,4-trimethylhexamethylenediamine, hydrazine, piperazine, 2-hydroxyethylethylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, poly(propylene glycol)diamine, poly(propylene glycol)triamine, poly(propylene glycol)tetraamine, 1,2-diaminopropane, 1,3-diaminopropane,

[0032] 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, nonaethylenedecamine, trimethylhexamethylenediamine, tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, triethylene-bis(trimethylene)hexamine, bis(3-aminoethyl)amine, bishexamethylenetriamine, 1,4-cyclohexanediamine, 4,4'-methylenebiscyclohexylamine, 4,4'-isopropylidenebiscyclohexylamine, norbornadiamine,

[0033] Bis(aminomethyl)cyclohexane, diaminodicyclohexylmethane, isophoronediamine, menthendiamine, bis(cyanoethyl)diethylenetriamine, 1,4-bis-(8-aminopropyl)-piperazine, 1-(2'-aminoethylpiperazine), 1-[2'-(2"-aminoethylamino)ethyl]piperazine, tricyclodecane diamine, amine compounds having a plurality of amino groups such as polyurea amine which is a reaction product of the above various polyamines and the above various isocyanate components,

[0034] Monoethanolamine, monoisopropanolamine, monobutanolamine, N-methylethanolamine, N-ethylethanolamine, N-methylpropanolamine, primary or secondary alkanolamines such as diethanolamine and diisopropanolamine,

[0035] Primary or secondary amines such as ethylamine, octylamine, laurylamine, myristylamine, stearylamine, oleylamine, diethylamine, dibutylamine, and distearylamine may be mentioned.

[0036] The blending amount of the amine compound (B) is preferably adjusted so that the amine value of the polyol composition is 1 mgKOH / g or more and 100 mgKOH / g or less, and is preferably blended so as to be 20 mgKOH / g or more and 80 mgKOH / g or less.

[0037] In addition, the amine value in this specification means the number of milligrams of KOH equivalent to the amount of HCl required to neutralize 1 g of the sample, and there is no particular limitation, and it can be calculated using a known method. When the chemical structure of the amine compound, and further, if necessary, the average molecular weight, etc. are known, it can be calculated from (the number of amino groups per molecule / average molecular weight) × 56.1 × 10,000. When the chemical structure, average molecular weight, etc. of the amine compound are unknown, it can be measured according to a known amine value measurement method, for example, JIS K7237-1995.

[0038] (Polyisocyanate composition (Y)) Polyisocyanate composition (Y) comprises a polyisocyanate compound (C) having a plurality of isocyanate groups. The polyisocyanate compound (C) also comprises a polyether polyurethane polyisocyanate (C1), which is a reaction product of a polyether polyol and a polyisocyanate compound.

[0039] The polyisocyanate compound used in the synthesis of polyether polyurethane polyisocyanate (C1) is not particularly limited and includes aromatic diisocyanates, aromatic aliphatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc., which can be used individually or in combination.

[0040] Examples of aromatic diisocyanates include, but are not limited to, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (also called polymeric MDI or crude MDI), 1,3-phenylenediisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylenediisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4''-triphenylmethane triisocyanate.

[0041] Aromatic aliphatic diisocyanates refer to aliphatic isocyanates having one or more aromatic rings in their molecule, and include, but are not limited to, m- or p-xylylene diisocyanate (also known as XDI) and α,α,α',α'-tetramethylxylylene diisocyanate (also known as TMXDI).

[0042] Examples of aliphatic diisocyanates include, but are not limited to, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0043] Examples of alicyclic diisocyanates include, but are not limited to, 3-isocyanate-methyl-3,5,5-trimethylcyclohexyl isocyanate, isophorone diisocyanate (also known as IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanate-methyl)cyclohexane.

[0044] As the polyether polyol used in the synthesis of polyether polyurethane polyisocyanate (C1), the same as those exemplified as polyol compound (A1) can be used.

[0045] The proportion of polyether polyurethane polyisocyanate (C1) in the polyisocyanate compound (C) can be adjusted as appropriate according to the desired physical properties, but as an example, it is 30% by mass or more, and as another example, 50% by mass or more. The entire amount of the polyisocyanate compound (C) may be polyether polyurethane polyisocyanate (C1).

[0046] The polyisocyanate compound (C) may further contain a polyisocyanate compound (C2) other than the polyether polyurethane polyisocyanate (C1). The polyisocyanate compound (C2) is not particularly limited and includes various diisocyanates exemplified as raw materials for the polyether polyurethane polyisocyanate (C1), as well as biuret, nurate, adduct, allophanate, carbodiimide modified, uretdione modified forms of these diisocyanates, and polyurethane polyisocyanates obtained by reacting these polyisocyanates with polyols. These can be used individually or in combination.

[0047] When the polyisocyanate compound (C2) includes polyurethane polyisocyanate, the polyol used in its synthesis can be the same as that exemplified as polyol compound (A). Polyether polyols, polyester polyols, aliphatic diols, and polyols with a molecular weight of 2500 g / mol or less are preferably used.

[0048] The adhesive of the present invention is used in a solvent-free form. In this specification, a solvent-type adhesive refers to a form in which the polyol composition (X) and polyisocyanate composition (Y) contain highly soluble organic solvents such as esters like ethyl acetate, butyl acetate, and cellosolve acetate, ketones like acetone, methyl ethyl ketone, isobutyl ketone, and cyclohexanone, ethers like tetrahydrofuran and dioxane, aromatic hydrocarbons like toluene and xylene, halogenated hydrocarbons like methylene chloride and ethylene chloride, dimethyl sulfoxide, and dimethyl sulfamide. A solvent-free adhesive refers to a form that substantially does not contain these organic solvents. If trace amounts of organic solvent remain in the polyol composition (X) and polyisocyanate composition (Y) due to incomplete removal of the components of the polyol composition (X) and polyisocyanate composition (Y) or organic solvents used as reaction media during the production of their raw materials, it is understood that the adhesive is substantially solvent-free. Furthermore, if the polyol composition (X) contains a low molecular weight alcohol, the low molecular weight alcohol reacts with the polyisocyanate composition (Y) to become part of the coating film, so it does not need to be volatilized after coating. Therefore, this form is also treated as a solvent-free adhesive, and the low molecular weight alcohol is not considered an organic solvent.

[0049] The adhesive of the present invention may contain components other than those described above, such as urethane catalysts, acid anhydrides, coupling agents, pigments, plasticizers, phosphoric acid derivatives, etc. These components may be included in either or both of the polyol composition (X) or the polyisocyanate composition (Y), or they may be prepared separately and mixed with the polyol composition (X) or polyisocyanate composition (Y) immediately before application of the adhesive.

[0050] The adhesive of the present invention may or may not contain an antioxidant. Examples of antioxidants include phosphoric acid-based antioxidants such as triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, trioleyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetra(C12-C15 alkyl)-4,4'-isopropylidene diphenyl diphosphite, bis(decyl)pentaerythritol diphosphite, and tristearyl phosphite. Examples include hindered phenol antioxidants such as pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-hydroxyphenyl)propionate, and benzyl acetate 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester. These may be used alone or in combination of two or more.

[0051] If the adhesive of the present invention contains an antioxidant, its content is, for example, 0.1% by mass or more and 5.0% by mass or less.

[0052] The adhesive of the present invention is preferably used when the ratio of the number of moles of isocyanate groups [NCO] in the polyisocyanate composition (Y) to the number of moles of hydroxyl groups [OH] in the polyol composition (X) is 0.5 to 10.0 ([NCO] / [OH], hereinafter also referred to as the isocyanate excess ratio). It is preferably used when the ratio is 0.5 to 6.5. The isocyanate excess ratio is 4.5 or less as one example, 4.0 or less as another example, and 3.5 or less as yet another example.

[0053] Furthermore, if the polyol composition (X) contains an amine compound (B), it is preferable to use it in a formulation such that the excess ratio of the number of moles of isocyanate groups [NCO] contained in the polyisocyanate composition (Y) ([NCO] / [OH+NH]) relative to the sum of the number of moles of hydroxyl groups [OH] and the number of moles of amino groups [NH] contained in the polyol composition (X) is 0.5 to 10.0, and more preferably 0.5 to 6.5. The excess ratio of isocyanate is, for example, 4.5 or less, for another example, 4.0 or less, and for yet another example, 3.5 or less.

[0054] (Urethane bond concentration, Urea bond concentration) The adhesive of the present invention is adjusted so that the urethane bond concentration after the reaction of the polyol composition (X) and the polyisocyanate composition (Y) is 2.0 mmol / g. This makes it possible to obtain recycled pellets with less yellowing in the recycling method described later. In addition, it is possible to suppress the generation of foreign matter above a certain size when the recycled pellets are molded. The urethane bond is formed, for example, by the reaction of a polyol compound (A) and a polyisocyanate compound (C).

[0055] The upper limit of the urethane bonding concentration is not particularly limited, but one example is 6.0 mmol / g. The urethane bonding concentration of the adhesive of the present invention is more preferably 2.5 mmol / g or more, and more preferably 4.5 mmol / g or less.

[0056] Furthermore, it is preferable that the adhesive of the present invention is adjusted so that the total concentration of urethane bonds and urea bonds after the reaction of the polyol composition (X) and the polyisocyanate composition (Y) is 2.5 mmol / g or more. This makes it possible to obtain recycled pellets with less yellowing in the recycling method described later. It also makes it possible to suppress the generation of foreign matter of a certain size or larger when the recycled pellets are molded. Urea bonds can be formed, for example, by the reaction of an amine compound (B) and a polyisocyanate compound (C), or by the reaction of water present in the system with excess polyisocyanate compound (C), but may be zero.

[0057] The upper limit of the total concentration of urethane and urea bonds is not particularly limited, but as an example, it is 6.0 mmol / g. The total concentration of urethane and urea bonds in the adhesive of the present invention is more preferably 3.0 mmol / g or more, and more preferably 4.5 mmol / g or less.

[0058] The concentrations of urethane and urea bonds in adhesives are adjusted by the [NCO] / [OH] (or [NCO] / [OH+NH]) ratio, the polyol compound used (with or without urethane and urea bonds), its molecular weight, and the polyisocyanate compound (with or without urethane and urea bonds).

[0059] The concentrations of urethane and urea bonds after the reaction of the adhesive can be calculated from the raw materials of the adhesive (polyol composition (X) and polyisocyanate composition (Y)).

[0060] <Laminate> The laminate of the present invention includes a first substrate, a second substrate, and an adhesive layer. The adhesive layer is a cured coating of the adhesive of the present invention and serves to bond the first substrate and the second substrate together.

[0061] (First Substrate) The first substrate can be any film or sheet (unless otherwise specified below, "film" is a general term for both films and sheets) that has excellent chemical and physical strength, without any particular restrictions. Examples of the first substrate include polyethylene terephthalate (PET) film, polystyrene film, polyamide film, polyacrylonitrile film, polyethylene film (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film, MDOPE: uniaxially oriented polyethylene film, OPE: biaxially oriented polyethylene film), polypropylene film (CPP: unoriented polypropylene film, OPP: biaxially oriented polypropylene film), polyolefin film such as ethylene vinyl alcohol copolymer, or polyvinyl alcohol copolymer film, which is a gas barrier film in which an olefin-based heat-sealable resin layer is provided on one or both sides of a gas barrier resin having gas barrier properties such as polyvinyl alcohol, polyvinyl alcohol film, ethylene-vinyl alcohol copolymer film, etc.

[0062] Furthermore, it is preferable to use a film formed from materials containing biomass-derived components. Biomass films are sold by various companies, and for example, sheets listed in the biomass certified product list provided by the Japan Organic Resources Association can be used.

[0063] A well-known example of a film made from biomass-derived ethylene glycol is derived from ethanol produced from biomass (biomass ethanol). For example, biomass-derived ethylene glycol can be obtained by conventionally known methods, such as a method that produces ethylene glycol via ethylene oxide from biomass ethanol. Alternatively, commercially available biomass ethylene glycol may be used; for example, the biomass ethylene glycol commercially available from India Glycol can be suitably used.

[0064] Alternatively, products using biomass raw materials, distinguished by their biomass plasticity as defined by ISO 16620 or ASTM D6866, are also available. Radioactive carbon-14C exists in the atmosphere at a ratio of 1 in 10¹² atoms, and this ratio does not change even in atmospheric carbon dioxide. Therefore, this ratio does not change in plants that fix carbon dioxide through photosynthesis. For this reason, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the proportion of plant-derived resin in the resin, i.e., the biomass plasticity, can be determined. Examples of plant-derived low-density polyethylene (PDI) biomass plastics with a biomass plastic content of 80% or more, preferably 90% or more, as defined by ISO 16620 or ASTM D6866, include Braskem's product names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films made from these materials can be suitably used.

[0065] The film may be stretched. A common stretching method involves melting and extruding the resin into a sheet using methods such as extrusion film formation, followed by simultaneous biaxial stretching or sequential biaxial stretching. In the case of sequential biaxial stretching, it is common to first perform longitudinal stretching, followed by transverse stretching. Specifically, a method combining longitudinal stretching using the speed difference between rolls and transverse stretching using a tenter is frequently used.

[0066] Various surface treatments, such as flame treatment or corona discharge treatment, may be applied to the film surface as needed to ensure that an adhesive layer free from defects such as film breakage or repulsion is formed.

[0067] Alternatively, an inorganic vapor-deposited film such as a metal vapor-deposited film with a metal layer such as aluminum, or a transparent vapor-deposited film with a laminated layer of metal oxides such as silica or alumina, or a barrier film containing a gas barrier layer such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, or vinylidene chloride may be used. When using a barrier film, it is preferable to use a transparent vapor-deposited film with a laminated layer of metal oxides such as silica or alumina, or a barrier film containing a gas barrier layer of polyvinyl alcohol or ethylene-vinyl alcohol copolymer.

[0068] The film thickness of the first substrate is not particularly limited and can be appropriately selected within the range of 1 to 300 μm from the viewpoint of moldability and transparency. Preferably, it is in the range of 1 to 100 μm.

[0069] (Second Substrate) The second substrate can be the same as the first substrate. In one embodiment of the present invention, the second substrate is a heat-sealable film (sealant film) that can melt and fuse with each other by heat, and the first substrate is a substrate that is not expected to act as a sealant film. In another embodiment of the present invention, the second substrate is a film in which a film that does not have heat-sealability and a heat-sealable resin layer (heat-seal layer) are laminated, and the first substrate is a substrate that is not expected to act as a sealant film.

[0070] Examples of heat-sealable resins include polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate ethyl copolymer, ethylene-propylene copolymer, methylpentene polymer, modified olefin resins obtained by modifying olefin resins such as polyethylene or polypropylene with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids, ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid terpolymer, cyclic polyolefin, cyclic olefin copolymer, polyethylene terephthalate (PET), polyacrylonitrile (PAN), ethylene vinyl alcohol copolymer, and gas barrier resins such as polyvinyl alcohol, with an olefin-based heat-sealable resin layer on one or both sides. Films, sheets, and other coatings made from one or more of these resins can be used as sealant films.

[0071] Any type of sealant film can be used, including unstretched, uniaxially oriented, and biaxially oriented films.

[0072] A biaxially stretched film can be obtained, for example, by longitudinally stretching it 2 to 4 times using a roll stretcher at 50 to 100°C, then transversely stretching it 3 to 5 times using a tenter stretcher in an atmosphere of 90 to 150°C, and subsequently heat-treating it using a tenter stretcher in an atmosphere of 100 to 240°C. Alternatively, films that have been simultaneously biaxially stretched or sequentially biaxially stretched may be used.

[0073] An easy-peel sealant film may be used as the sealant film. Any of the easy-peel sealant films, including interfacial peel type, cohesive peel type, and interlayer peel type, can be applied and can be appropriately selected according to the type of packaging material and required characteristics described later. The indicator of easy peelability is appropriately set according to the type of packaging material and required characteristics, but as an example, the seal strength is 2 to 20 N / 15 mm. For example, easy peelability can be achieved by a phase-separated polymer blend combining polypropylene with high-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, etc.

[0074] If the second substrate is a film in which a film that does not have heat-sealing properties and a resin layer that does have heat-sealing properties (heat-sealing layer) are laminated, the second substrate can be, for example, a film that does not have heat-sealing properties to which a heat-sealing agent containing a heat-sealing resin is applied.

[0075] Examples of heat-sealable resins include thermoplastic resins such as shellacs, rosins, rosin-modified maleic acid resins, rosin-modified phenolic resins, nitrated cotton, cellulose acetate, cellulose acetylpropionate, cellulose acetyl butyrate, chlorinated rubber, cyclized rubber, vinyl chloride, vinylidene chloride, polyamide resins, vinyl chloride-vinyl acetate copolymers, polyester resins, ketone resins, butyral resins, chlorinated polypropylene resins, chlorinated polyethylene resins, chlorinated ethylene vinyl acetate resins, ethylene vinyl acetate resins, acrylic resins, urethane resins, ethylene-vinyl alcohol resins, styrene maleic acid resins, casein, and alkyd resins. These may be used individually or in combination of two or more types. In the present invention, it is preferable not to use chlorine-containing resins such as vinyl chloride-vinyl acetate copolymers or resins having nitro groups such as nitrated cotton.

[0076] The heat sealant may be in any form, such as a type in which these resins are dissolved in an organic solvent, a type in which they are dissolved in water or an aqueous organic solvent, or an emulsion type in which acrylic emulsions, urethane emulsions, polyvinyl alcohol resins, ethylene-vinyl alcohol emulsions, ethylene-methacrylic acid emulsions, polyolefin emulsions, ethylene vinyl acetate emulsions, etc., are dispersed in water or an aqueous organic solvent.

[0077] There are no particular restrictions on the organic solvents, but examples include aromatic hydrocarbons such as toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; and ester-based organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate.

[0078] Examples of aqueous organic solvents include alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, methyl ethyl ketone, and cycloxanone; and glycol ethers such as ethylene glycol (mono, di)methyl ether, ethylene glycol (mono, di)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di)methyl ether, diethylene glycol (mono, di)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di)methyl ether, propylene glycol (mono, di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di)methyl ether.

[0079] Heat sealants may contain components other than heat-sealable resins and solvents. Examples of such components include waxes, fillers, defoamers, viscosity modifiers, leveling agents, tackifiers, preservatives, antibacterial agents, rust inhibitors, and antioxidants.

[0080] Known methods can be used for applying the heat sealant. For example, roll coaters, gravure coaters, flexo coaters, air doctor coaters, blade coaters, air knife coaters, squeeze coaters, impregnation coaters, transfer roll coaters, kiss coaters, curtain coaters, cast coaters, spray coaters, die coaters, offset printing presses, screen printing presses, etc. may be used. A drying process in an oven or the like may also be included after coating.

[0081] The thickness of the heat seal layer (amount of heat sealant applied (solid content)) can be arbitrary; for example, 0.5 g / m². ２ ~5g / m ２ That is the case.

[0082] The film thickness of the second substrate can be arbitrarily selected, but for example, when applied to the packaging material described later, it is selected in the range of 5 to 500 μm. It is more preferably 10 to 250 μm, and even more preferably 15 to 100 μm.

[0083] The second substrate may be an inorganic vapor-deposited film such as a metal vapor-deposited film with a metal layer such as aluminum deposited on it, or a transparent vapor-deposited film with a laminated layer of metal oxides such as silica or alumina, or a barrier film containing a gas barrier layer such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, or vinylidene chloride. When a barrier film is used as the second substrate, it is preferable to use a transparent vapor-deposited film with a laminated layer of metal oxides such as silica or alumina, or a barrier film containing a gas barrier layer of polyvinyl alcohol or ethylene-vinyl alcohol copolymer.

[0084] The second substrate preferably contains the same type of resin as the first substrate. This makes it possible to create a laminate with excellent recyclability. The first and second substrates preferably both contain polyester resin or olefin resin, and more preferably both contain olefin resin. When both the first and second substrates contain polyester resin, the first substrate is, for example, a PET film, and the second substrate is a heat-sealable PET film. When both the first and second substrates contain olefin resin, the first substrate is selected from, for example, biaxially oriented polypropylene film (OPP), biaxially oriented polyethylene film (OPE), uniaxially oriented polyethylene film (MDOPE), and high-density polyethylene film (HDPE), and the second substrate is selected from unoriented polypropylene film (CPP) and low-density polyethylene film (LLDPE).

[0085] (Adhesive layer) The adhesive layer is a cured coating film of the adhesive of the present invention, and its urethane bond / urea bond concentration is 2.5 mmol / g or more. The adhesive layer is formed by mixing a polyol composition and a polyisocyanate composition so that the urethane bond / urea bond concentration of the adhesive layer is 2.5 mmol / g or more, with an upper limit of 6.0 mmol / g or less as an example, preferably 3.0 mmol / g or more, and 4.5 mmol / g or less. This mixture is applied to either the first substrate or the second substrate either directly or via a printing layer or other optionally provided layer described later, and after bonding with the other substrate, an aging treatment is performed to form the adhesive layer.

[0086] Alternatively, the adhesive layer can be formed by applying a polyol composition to one of the first and second substrates and a polyisocyanate composition to the other substrate in a blending ratio such that the urethane bond / urea bond concentration is 2.5 mmol / g or more, bonding the first and second substrates together so that the polyol composition and the polyisocyanate composition are in contact, and then performing an aging treatment. In this case as well, the polyol composition and the polyisocyanate composition may be applied directly to the first and second substrates, respectively, or they may be applied via an optionally provided layer such as a printing layer.

[0087] The aging temperature is typically room temperature to 70°C, and the aging time is typically 6 to 240 hours. The amount of adhesive applied is adjusted as needed, but one example is 1 g / m². ２ 5g / m or more ２ The following applies:

[0088] (Printed Layer) The laminate of the present invention may include layers other than the first substrate, the second substrate, and the adhesive layer. An example of such a layer is a printed layer. The printed layer is a layer printed using printing ink between the first substrate and the adhesive layer, or on the surface of the first substrate opposite the adhesive layer, and may form characters, figures, symbols, or other desired patterns or information.

[0089] The printing method and inks are not particularly limited, and known printing methods and inks can be used. The films used as the substrate often utilize printing inks produced by gravure printing, flexographic printing, lithographic offset printing, and inkjet recording printing methods. Printing inks combining these methods with curing methods using active energy rays such as ultraviolet (UV), LED, or electron beam (EB), or curing methods using heat, are also used. Furthermore, depending on the solvent used, the inks may be referred to as water-based inks or organic solvent-based inks.

[0090] Specifically, these include gravure printing inks and flexographic printing inks (in some industries, gravure printing inks and flexographic printing inks are referred to as liquid inks), UV-curable inks for lithographic offset printing, electron beam-curable inks for lithographic offset printing, UV-curable inks for inkjet recording printing, and electron beam-curable inks for inkjet recording printing. Biomass inks made from biomass raw materials are also used as appropriate.

[0091] The printing ink may contain resin, colorant, and solvent as essential components, or it may be a so-called clear ink that contains resin and solvent but substantially no colorant. The printing layer may be provided over the entire surface of the first substrate or only on a portion of it.

[0092] Taking the case where the printing ink is gravure printing ink or flexographic printing ink as an example, the resin used in the printing ink is not particularly limited, and examples include acrylic resin, polyester resin, styrene resin, styrene-maleic acid resin, maleic acid resin, polyamide resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyvinyl acetal obtained by reacting vinyl acetate resin with an aldehyde such as butyraldehyde under acidic conditions, polyvinyl chloride resin, chlorinated polypropylene resin, cellulose resin, epoxy resin, alkyd resin, rosin resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin, etc., and one or more of these can be used in combination. Preferably, at least one or more selected from polyurethane resin and polyvinyl acetal are used. Furthermore, it is preferable that the resin used in the printing ink contains 0.8% by mass or less of chlorine-containing resins such as vinyl chloride-vinyl acetate copolymer resins, or resins having nitro groups such as nitrocellulose resins. It is also preferable that the ink does not contain chlorine-containing resins such as vinyl chloride-vinyl acetate copolymer resins, or resins having nitro groups such as nitrocellulose resins.

[0093] Colorants used in printing inks include inorganic pigments such as titanium dioxide, iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, Prussian blue, ultramarine, carbon black, and graphite; organic pigments such as soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments; and extender pigments such as calcium carbonate, kaolin clay, barium sulfate, aluminum hydroxide, and talc.

[0094] The organic solvents used in printing inks preferably do not contain aromatic hydrocarbon organic solvents. More specifically, examples include alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. One or more of these can be used in combination.

[0095] In the liquid printing ink used in this invention, it is also preferable to use gravure printing ink or flexographic printing ink made from plant-derived raw materials, taking into consideration the construction of a sustainable circular society.

[0096] Examples of plant-derived raw materials include cellulose acetate propionate resin and nitrated cotton resins, polyamide resins using dimer acids or polymerized fatty acids derived from natural oils such as soybean oil, palm oil, and rice bran oil, as well as polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid, as well as polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer ol, and isosorbide, and polyisocyanates such as 1,5-pentamethylene diisocyanate and dimer isocyanate. Biomass polyurethanes synthesized from these plant-derived raw materials and rosin resins are also available.

[0097] For biomass gravure printing inks or flexographic printing inks, commercially available products listed by the Japan Organic Resources Association can also be used.

[0098] The area of ​​the printed layer relative to the area of ​​the laminate or packaging material is preferably 50% or less. Furthermore, the printed layer is preferably provided in a light color. Specifically, the density measured using a densitometer with ISO status T as the density standard, a viewing angle of 2°, and a light source D50 is preferably 0.8 or less, more preferably 0.5 or less. For example, the eXactAdvance manufactured by X-rite can be used as the densitometer.

[0099] (Third Substrate) The laminate of the present invention may include a third substrate in addition to the first substrate and the second substrate. The third substrate can be the same as the first substrate. In one embodiment of the present invention, the second substrate is a heat-sealable film (sealant film) that can melt and fuse with each other by heat, and the first substrate and the third substrate are substrates that are not expected to act as sealant films. In another embodiment of the present invention, the first substrate, the second substrate and the third substrate are all substrates that are not expected to act as sealant films.

[0100] If the laminate of the present invention includes a third substrate, the third substrate is placed between the first substrate and the second substrate, and the first substrate and the third substrate, and the third substrate and the second substrate are bonded together, either directly or via a layer as necessary, using the adhesive of the present invention. The adhesive layer placed between the first substrate and the third substrate and the adhesive layer placed between the third substrate and the second substrate may be formed from the same adhesive or from different adhesives.

[0101] The third substrate preferably contains the same type of resin as the first and second substrates. This makes it possible to create a laminate with excellent recyclability. The first, second, and third substrates preferably all contain polyester resin or olefin resin, and more preferably olefin resin. When the first, second, and third substrates all contain polyester resin, the first and third substrates are, for example, PET films, and the second substrate is a heat-sealable PET film. When the first, second, and third substrates all contain olefin resin, the first and third substrates are selected from, for example, biaxially oriented polypropylene film (OPP), biaxially oriented polyethylene film (OPE), uniaxially oriented polyethylene film (MDOPE), and high-density polyethylene film (HDPE), and the second substrate is selected from unoriented polypropylene film (CPP) and low-density polyethylene film (LLDPE).

[0102] (Barrier Coat Layer) The laminate of the present invention may include layers other than those described above. An example of such a layer is a barrier coat layer. The barrier coat layer is a layer that prevents the permeation of oxygen and water vapor, and can be provided at any position in the laminate of the present invention by applying and drying a barrier coat agent.

[0103] Examples of barrier coating agents include a barrier coating agent (1) containing a vinyl alcohol-based polymer and an aqueous solvent.

[0104] Specific examples of vinyl alcohol polymers include polyvinyl alcohol, ethylene vinyl alcohol, and polyvinyl butyral. Vinyl alcohol polymers may also have reactive functional groups other than hydroxyl groups, such as acetoacetyl groups, carboxyl groups, anionic carboxyl groups, sulfonic acid groups, and anionic sulfonic acid groups. These may be used individually or in combination of two or more.

[0105] Examples of the aqueous solvent include glycols such as water, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, and hexanediol; glycol esters such as propylene glycol laurate; diethylene glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, and carbitol; glycol ethers such as cellosolve including propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether; alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, and pentyl alcohol; lactones such as sulfolane, ester, ketone, and γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidone; glycerin and its polyalkylene oxide adducts, etc. The aqueous solvent can be used alone or in combination of two or more kinds.

[0106] The barrier coating agent (1) may further contain additives such as a layered inorganic compound, a crosslinking agent capable of reacting with a functional group of a vinyl alcohol-based polymer, an adhesion improver, an inorganic filler, an antifoaming agent, a stabilizer (such as an antioxidant, a heat stabilizer, an ultraviolet absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, a leveling agent, etc.

[0107] As the barrier coating agent (1), commercially available products can also be used. Examples include Excevia (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., SunBar (registered trademark) series manufactured by Sankyo Chemical Co., Ltd., Takelac WPB (registered trademark) series manufactured by Mitsui Chemicals, Inc., LG-OX manufactured by Tokyo Ink Co., Ltd., etc.

[0108] Examples of the barrier coating agent include a water-soluble polymer having a hydroxyl group and Si(OR １ ) ４ , or R ２ Si(OR ３ ) ３ (where OR １and OR ３ represents a hydrolyzable group, R ２ Examples of gas barrier coating agents (2) include one or more silicon compounds represented by (where represents an organic functional group), or hydrolyzed products of the silicon compounds.

[0109] Examples of water-soluble polymers containing hydroxyl groups include vinyl alcohol polymers, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, and sodium alginate.

[0110] Examples of silicon compounds or hydrolyzed products of the silicon compound include tetraethyl silicate (Si(OC) ２ H ５ ) ４ Examples include tetraalkoxysilanes such as tetramethylsilate (hereinafter sometimes referred to as TEOS), trialkoxysilanes such as trimethoxymethylsilane, triethoxymethylsilane, and trimethoxyvinylsilane, dialkoxysilanes such as dimethoxydimethylsilane and diethoxydimethylsilane, monoalkoxysilanes such as methoxytrimethylsilane and ethoxytrimethylsilane, or their hydrolysates or partial hydrolysates.

[0111] TEOS is preferred because it is relatively stable in aqueous solvents after hydrolysis. ２ Si ( OR ３ ) ３ R ２ The group is preferably a vinyl group, epoxy group, acryloyl group, methacryloxy group, ureido group, or isocyanate group.

[0112] Barrier coating agent (2) may contain components other than those mentioned above. Examples of such components include other water-soluble polymers (e.g., sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.), fragrances, rust inhibitors, colorants, fillers, defoamers, UV absorbers, fluorescent whitening agents, liquid paraffins, bitter components (e.g., denatonium benzoate, etc.). Barrier coating agent (2) can also use the same aqueous solvent as gas barrier coating agent (1).

[0113] Examples of barrier coating agents include a barrier coating agent (3) comprising a polyester polyol, which is a reaction product of an acid component containing an ortho-directing polycarboxylic acid or a meta-directing polycarboxylic acid and a polyol component, and an isocyanate compound.

[0114] Examples of ortho-directing polycarboxylic acids include orthophthalic acid or its acid anhydride, naphthalene 2,3-dicarboxylic acid or its acid anhydride, naphthalene 1,2-dicarboxylic acid or its acid anhydride, anthraquinone 2,3-dicarboxylic acid or its acid anhydride, and 2,3-anthracenecarboxylic acid or its acid anhydride. These compounds may have substituents on any carbon atom of the aromatic ring. Examples of substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, or naphthyl group.

[0115] Examples of meta-directing polycarboxylic acids include isophthalic acid and 1,3-naphthalenedicarboxylic acid. These compounds may have substituents on any carbon atom of the aromatic ring, similar to those exemplified in the description of ortho-directing polycarboxylic acids.

[0116] The polycarboxylic acids used in the synthesis of polyester polyols may include polycarboxylic acids other than ortho-directing or meta-directing polycarboxylic acids. These polycarboxylic acids include aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated bond-containing polycarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid; alicyclic polycarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; terephthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 1,5-anthracenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, and 1,4-anthracenedicarboxylic acid. Examples of aromatic polycarboxylic acids include spiral dicarboxylic acid, 2,6-anthracenedicarboxylic acid, 2,7-anthracenedicarboxylic acid, 1,8-anthracenedicarboxylic acid, 9,10-anthracenedicarboxylic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid and acid anhydrides or ester-forming derivatives of these dicarboxylic acids, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid and ester-forming derivatives of these dihydroxycarboxylic acids, and one or more of these can be used in combination. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, and its acid anhydrides are preferred.

[0117] When the polycarboxylic acid includes polycarboxylic acids other than ortho-directing polycarboxylic acids or meta-directing polycarboxylic acids, it is preferable that the proportion of ortho-directing polycarboxylic acids or meta-directing polycarboxylic acids to the total amount of polycarboxylic acids is 40 to 100% by mass.

[0118] The polyhydric alcohols used in the synthesis of polyester polyols preferably include dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol, and trihydric alcohols such as glycerol, trimethylolethane, and trimethylolpropane. Among these, the inclusion of ethylene glycol and glycerol is more preferable. The inclusion of glycerol is particularly preferable. Glycerol is preferably present in an amount of 10% to 100% by mass in the polyhydric alcohol.

[0119] Polyhydric alcohols other than those listed above may be used in combination. Examples include aliphatic diols such as 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol; trihydric or higher polyhydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl) isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythulitol; hydroquinone, resorcinol, catechol, naphthalenediol, biphenol, bisphenol A, hisphenol F, tetramethylbiphenol, and aromatic polyhydric phenols such as ethylene oxide extensions thereof and hydrogenated alicyclic groups.

[0120] If the polyester polyol has three or more hydroxyl groups, some of the hydroxyl groups may be modified with a polycarboxylic acid or its acid anhydride. Preferably, the proportion of hydroxyl groups modified with a polycarboxylic acid is 1 / 3 or less of the total hydroxyl groups present in the polyester polyol. Examples of polycarboxylic acids used for modification include, but are not limited to, succinic anhydride, maleic acid, fumaric acid, 1,2-cyclohexanedicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, trimellitic anhydride, oleic acid, and sorbic acid.

[0121] The polyester polyol may also be a polyester polyurethane polyol with a number average molecular weight of 1,000 to 15,000, obtained by urethane elongation through reaction with a diisocyanate compound. Since the urethane-elongated polyester polyol contains molecular weight components above a certain level and urethane bonds, it has excellent gas barrier properties and superior initial cohesive strength.

[0122] The isocyanate compound used in the barrier coating agent (3) can be the same as the polyisocyanate compound used in the adhesive (1). It is preferable to use one that has an aromatic ring or an aliphatic ring. Examples of isocyanate compounds having aromatic or aliphatic rings include toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, or trimers of these isocyanate compounds, and adducts obtained by reacting an excess amount of these isocyanate compounds with low molecular weight active hydrogen compounds such as ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, metaxylylenediamine and their alkylene oxide adducts, various polyester resins, polyether polyols, and high molecular weight active hydrogen compounds of polyamides. The isocyanate compounds may be used alone or in combination of multiple types of isocyanate compounds.

[0123] The barrier coating agent (3) may also preferably contain a compound having an active hydrogen group. Examples of active hydrogen groups in compounds containing active hydrogen include hydroxyl groups, amino groups, imino groups, carboxylic acids, urea groups, or SH groups. Among these, hydroxyl groups, amino groups, or SH groups are preferred.

[0124] When the solubility parameter of the compound containing active hydrogen is 29.5 or less, the compatibility between the polyester polyol and the isocyanate compound is improved, the compound containing active hydrogen is uniformly distributed in the barrier coat layer, and an effect of improving gas barrier properties can be expected. In this specification, the solubility parameter shall be the δT value included in the Hansen Solubility Parameter Calculation Software (HSPiP) or the δT value calculated using the SMILES notation.

[0125] Compounds having a hydroxyl group as an active hydrogen group include alkanols such as octanol and decanol, aliphatic diols such as 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, 3,3-dimethylolheptane, octanediol, and decanediol, alicyclic alcohols such as 1,3- or 1,4-cyclohexanedimethanol and 1,3- or 1,4-cyclohexanediol, aromatic alcohols such as salicylic alcohol and vanillyl alcohol, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, and 2,6- Examples include dihydric alcohols such as dimethyl-1-octen-3,8-diol, bisphenol A, diethylene glycol, triethylene glycol, and dipropylene glycol; trihydric alcohols such as glycerin, trimethylolpropane, and triisopropanolamine; tetrahydric alcohols such as tetramethylolmethane (pentaerythritol) and diglycerin; pentahydric alcohols such as xylitol; hexahydric alcohols such as sorbitol, mannitol, allitol, isitol, dalcitol, althritol, inositol, and dipentaerythritol; and heptahydric alcohols such as perseitol.

[0126] Compounds having an amino group as an active hydrogen group include, for example, aliphatic amines such as octylamine, decaneamine, 1,8-diaminooctane, and 1,10-diaminodecane; alicyclic amines such as isophoronediamine, norbornenediamine, bis(aminomethyl)cyclohexane, cyclohexanediamine, diaminodicyclohexylmethane, and methylenebis(methylcyclohexaneamine); and aromatic amines such as 1-xylylenediamine, N-benzylethylenediamine, phenylenediamine, diaminodiphenylmethane, diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, toluenediamine, and diethyltoluenediamine.

[0127] Examples of compounds having an SH group as an active hydrogen group include hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, undecyl mercaptan, and dodecyl mercaptan. Examples include tridecyl mercaptan, tetradecyl mercaptan, pentadecyl mercaptan, mercaptophenol, mercaptopropionic acid, mercaptobutyric acid, 1,4-butanedithiol, 2-mercaptobenzothiazole, 3-mercapto-1,2-propanediol, mercaptomethylbutanol, 3-mercapto-2-methylpentanol, 3-mercapto-3-methylbutanol, 4-ethoxy-2-methyl-2-butanethiol, hexanethiol, dimethylthiophenol, 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolpropanetris(3-mercaptobutyrate), pentaerythritoltetrakis(3-mercaptobutyrate), etc.

[0128] Compounds containing active hydrogen may be used individually or in combination of multiple types. Isosorbide, tris(2-hydroxyethyl) isocyanurate, trimethylolpropane, dipentaerythritol, and 1,4-cyclohexanedimethanol are preferred.

[0129] The amount of the compound containing active hydrogen is preferably 0.5% by mass or more and 20% by mass or less relative to the solid content of the barrier coating agent (3).

[0130] The barrier coating agent (3) may further contain layered inorganic compounds, acid anhydrides, oxygen scavengers, inorganic fillers, dispersants (if inorganic materials are used), stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, leveling agents, slip enhancers, etc.

[0131] The barrier coating agent (3) may be diluted with an organic solvent. Examples of organic solvents include ester solvents such as ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone and 2-butanone; ether solvents such as tetrahydrofuran; aliphatic solvents such as hexane and cyclohexane; and aromatic solvents such as toluene.

[0132] (Heat-resistant coating layer) The laminate of the present invention may include layers other than those described above. An example of such a layer is a heat-resistant coating layer. The heat-resistant coating layer is a layer that has the function of improving the heat resistance of the laminate of the present invention, and can be provided at any position of the laminate of the present invention by applying and drying a heat-resistant coating agent.

[0133] To illustrate with an example where the laminate of the present invention is used as a component for packaging materials to wrap contents, if the outermost base material when the bag is formed and filled with contents is a film with low heat resistance, such as a polyethylene film or a polypropylene film, there is a risk that the laminate may shrink due to heat when forming the bag by heat sealing. Such problems can be suppressed by providing a heat-resistant coating layer.

[0134] The heat-resistant coating layer is preferably positioned outside the outermost substrate among the substrates constituting the laminate, as viewed from the contents when the bag is made. For example, if the first substrate is the outermost substrate among the substrates constituting the laminate of the present invention, and the printing layer is provided between the first substrate and the adhesive layer, the heat-resistant coating layer is preferably provided on the side of the first substrate opposite to the adhesive layer. Alternatively, if the first substrate is the outermost substrate among the substrates constituting the laminate of the present invention, and the printing layer is provided on the side of the first substrate opposite to the adhesive layer, the heat-resistant coating layer may be positioned between the printing layer and the first substrate, or the printing layer may be positioned between the heat-resistant coating layer and the first substrate.

[0135] Examples of heat-resistant coating agents include coating agents containing compounds having a cellulose skeleton, benzene ring skeleton, isocyanuryl ring skeleton, or alicyclic skeleton, the glass transition temperature (hereinafter sometimes referred to as Tg) of the homopolymer being 100°C or higher. Specific examples of such compounds include cellulose derivatives such as cellulose acetate, cellulose propionate, and cellulose butyrate; polyester resins having a benzene ring such as phthalic acid, naphthalenedicarboxylic acid, and ethylene oxide (hereinafter sometimes referred to as EO) adduct of bisphenol A, and / or alicyclic skeletons such as cyclopentanediol and dimethylol tricyclodecane; or urethane resins bonded with aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalenediisocyanate; alicyclic isocyanates such as isophorone diisocyanate and norbornene diisocyanate; and / or isocyanuryl triisocyanate with polyols and / or tris(2-hydroxyethyl) isocyanurate. Furthermore, polyisocyanates using the aforementioned isocyanates may be used as curing agents. Compounds having a benzene ring and an unsaturated double bond, such as styrene and phenoxydiethylene glycol acrylate, and / or compounds having an alicyclic structure and an unsaturated double bond, such as isobornyl acrylate and dicyclopentanyl acrylate, and radical copolymers such as (meth)acrylates can also be preferably used. In addition, resins with a low Tg may be mixed in to improve adhesion to olefin films.

[0136] For heat-resistant coatings, it is preferable to use inorganic fine particles such as alumina, magnesia, titania, zirconia, and silica (quartz, fumed silica, precipitated silica, anhydrous silicic acid, fused silica, crystalline silica, ultrafine amorphous silica, etc.) as aggregates because they have excellent heat resistance. Alternatively, boron nitride, aluminum nitride, aluminum oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, etc. are preferred because they have excellent thermal conductivity. Inorganic fine particles may be used individually or in combination of multiple types.

[0137] The shape of the silica nanoparticles is not particularly limited; spherical, hollow, porous, rod-shaped, plate-shaped, fibrous, or irregularly shaped nanoparticles can be used. For example, commercially available hollow silica nanoparticles include Silinax manufactured by Nippon Steel Mining Co., Ltd.

[0138] The primary particle size of the inorganic fine particles is preferably in the range of 5 nm to 200 nm. More preferably, it is 10 nm to 100 nm. The inorganic fine particles can be blended in a ratio of 5 to 90% by weight relative to the total solid content of the heat-resistant coating agent and the inorganic fine particles, and the blending amount can be adjusted as needed depending on the purpose. In particular, a ratio of 20% by mass or more is preferred.

[0139] The heat-resistant coating agent may be colored. There are no particular limitations on the coloring agent, and examples include inorganic pigments, organic pigments, and dyes used in general inks, paints, and recording materials, such as those used in the printing layer described later.

[0140] Heat-resistant coatings can use waxes, silicone additives, and organic beads. Specifically, waxes such as amide wax, polypropylene wax, polyethylene wax, paraffin wax, carnauba wax, and rice wax, ethylene oxide (EO) adducts of dimethylsiloxane, silicone additives of silicone-modified materials, and organic beads made of acrylic, nylon, urethane, or epoxy can be added.

[0141] There are no particular restrictions on the solvent used in the heat-resistant coating agent, but examples include aromatic hydrocarbon organic solvents such as water, toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, and decane; and various ester-based organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate. Furthermore, examples of water-miscible organic solvents include alcohol-based solvents such as methanol, ethanol, propanol, butanol, and isopropyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, and cycloxanone; and glycol ether-based solvents such as ethylene glycol (mono, di)methyl ether, ethylene glycol (mono, di)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di)methyl ether, diethylene glycol (mono, di)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di)methyl ether, propylene glycol (mono, di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di)methyl ether. These can be used individually or in combination of two or more. In addition, defoamers and leveling agents may be used to more effectively carry out the coating.

[0142] Heat-resistant coating agents can also be commercially available. Examples include SUNSYS FS241 from Sun Chemical Co., Ltd., DH-S004 / DH-HARDENER P-60 from DIC Corporation, and ThermoGloss 463 from Michaelman Corporation.

[0143] <Packaging Material> The packaging material of the present invention consists of the laminate described above. As an example, the laminate is made into a bag, but the layer structure can be changed depending on the contents, usage environment, and usage form.

[0144] When the packaging material of the present invention is made by forming a bag from the laminate described above, for example, it is obtained by overlapping the heat-seal layers of the laminate facing each other and then heat-sealing the peripheral edges. As for the bag-making method, the laminate of the present invention can be folded or overlapped so that the inner layer surfaces (sealant film surfaces) face each other, and the peripheral edges can be heat-sealed in the form of, for example, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope-type seal type, a gusset-type seal type, a pleated seal type, a flat-bottom seal type, a square-bottom seal type, a gusset type, or other heat-seal types. The packaging material of the present invention can take various forms depending on the contents, usage environment, and usage form. Self-standing packaging materials (standing pouches) are also possible. As for the heat-sealing method, known methods such as bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals can be used.

[0145] The use of the packaging material is not particularly limited. The contents that can be filled include confectionery such as rice crackers, bean snacks, nuts, biscuits / cookies, wafers, marshmallows, pies, semi-moist cakes, candies, and snack foods; staples such as bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged rice, zosui, porridge, packaged mochi, and cereal foods; processed agricultural products such as pickles, boiled beans, natto, miso, frozen tofu, tofu, enoki mushrooms, konjac, processed wild vegetables, jams, peanut butter, salads, frozen vegetables, and processed potato products; processed livestock products such as ham, bacon, sausages, processed chicken products, and corned beef; and fish ham and sausages. Examples of processed seafood products include fish paste products, kamaboko (fish cake), nori (seaweed), tsukudani (simmered seafood), katsuobushi (dried bonito flakes), shiokara (salted seafood), smoked salmon, and spicy mentaiko (pollock roe); fruit pulp such as peaches, oranges, pineapples, apples, pears, and cherries; vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes; frozen and chilled prepared foods such as hamburgers, meatballs, fried seafood, gyoza (dumplings), and croquettes; dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula; liquid seasonings; retort curry; and pet food. Alternatively, it can be used as packaging material for cigarettes, disposable hand warmers, pharmaceuticals such as intravenous fluid packs, cosmetics, and vacuum insulation materials.

[0146] <Recycling Method> The recycling method of the present invention involves melting and kneading the laminate and packaging material of the present invention while the first base material and the second base material are bonded together by an adhesive layer. The recycling method of the present invention will be described in detail below.

[0147] (Apparatus) The extrusion apparatus used in the recycling method of the present invention may be any apparatus capable of extruding a general thermoplastic resin after melting and kneading it. The extrusion apparatus has a supply port for supplying a material such as a thermoplastic resin, a melt-kneading section for melting and kneading the material supplied from the supply port, and a discharge section for discharging the material melted and kneaded in the melt-kneading section. The extrusion apparatus may also be equipped with a pelletizer for shredding the material discharged from the discharge section to a predetermined length. Furthermore, it may be equipped with a cooling section for cooling.

[0148] The melting and mixing section comprises, for example, a cylinder with a screw inside and a heat source such as an electric heater. A discharge section is provided at the tip of the cylinder. The cylinder may also be provided with a supply port such as a hopper for supplying material. Furthermore, in order to prevent foreign matter from entering the pellets described later, it is preferable that a screen mesh is provided inside the cylinder on the tip side of the screw.

[0149] In the melting and mixing section, shear heat is generated from the material itself due to the shear action caused by the rotation of a screw located inside the cylinder and heating by an electric heater, etc., and the material is melted and mixed. The material melted and mixed in the melting and mixing section passes through a screen mesh, which is installed as needed, and is discharged from the discharge section. The discharge section may be equipped with a die of a predetermined shape. The material discharged from the discharge section solidifies or loses its fluidity upon cooling and becomes recycled plastic.

[0150] The screw configuration is not particularly limited. For example, it may have known structures such as a single-screw extruder, a twin-screw extruder, and a rotor-type twin-screw kneader. In one embodiment, the screw diameter is 25 to 400 mm, preferably 50 to 300 mm, and more preferably 100 to 250 mm. In one embodiment, the effective screw length (L / D) is 15 to 45, preferably 20 to 40, and more preferably 25 to 35. In the effective screw length (L / D), L represents the screw length and D represents the screw diameter.

[0151] The cylinder diameter is larger than the screw diameter, and a gap usually exists between them. In one embodiment, the size of the gap is 0.01 to 1 mm, preferably 0.05 to 0.7 mm, and more preferably 0.1 to 0.5 mm.

[0152] In one embodiment, the screw compression ratio is 2 to 5, preferably 2.5 to 4.5, and more preferably 3.4 to 3.7. The screw compression ratio refers to the ratio (V1 / V2) of the volume per pitch of the screw groove near the material supply section of the recycled plastic (V1) to the volume per pitch of the screw groove near the discharge section (V2).

[0153] The materials used to construct the screw are not particularly limited, and known materials can be used. From the viewpoint of preventing foreign matter contamination due to wear, it is preferable that the screw be made of stainless steel. Furthermore, various processes can be applied to the surface of the screw. Examples include nitriding, quenching, and powder metal quenching. From the viewpoint of preventing wear, it is preferable to apply powder metal quenching. As a combination of the screw's constituent material and surface treatment, a form in which stainless steel is subjected to powder metal quenching is more preferable.

[0154] Screen meshes can be woven in various ways, such as plain weave, twill weave, plain quilt weave, and quilt weave, or they can be made of perforated metal. The size of the screen mesh is preferably 40 mesh or more, more preferably 80 mesh or more, and even more preferably 120 mesh or more, taking into consideration the pressure and clogging of the discharge section. In one embodiment, the size of the screen mesh is 250 mesh or less, preferably 200 mesh or less.

[0155] (Melting and Kneading Process) In the method for producing recycled plastic of the present invention, the laminate or packaging material described above is heated and melted, and then kneaded. The melting temperature can be adjusted considering the glass transition temperature and melting temperature of the resin, the shape when pelletized, the pressure applied in the molding process, etc. For example, it is 120°C to 280°C, preferably 160°C to 250°C. For example, the rotation speed of the screw during kneading is 50 rpm to 900 rpm, preferably 80 rpm to 800 rpm, and more preferably 100 to 500 rpm. For example, the shear rate of the screw is 200 to 4000 / sec, preferably 300 to 3500 / sec, and more preferably 400 to 3000 / sec.

[0156] The filling rate of the laminate and packaging material within the extruder is, for example, 50 to 100% by volume, preferably 65 to 95% by volume, and more preferably 80 to 90% by volume, relative to the void volume within the extruder. The void volume within the extruder refers to the cylinder volume minus the screw volume.

[0157] (Pelletization) The melt-kneaded laminate or packaging material is extruded from an extruder, cooled, and shredded to become pellets of the recycled plastic of the present invention. The discharge rate of the extruder can be adjusted as appropriate depending on the size of the device, the production quantity, etc.

[0158] The resin pressure at the tip discharge section of the extruder (hereinafter also referred to as discharge pressure) is preferably 18 MPa or less, more preferably 15 MPa or less, even more preferably 10 MPa or less, and particularly preferably 8 MPa or less. In one embodiment, the resin discharge pressure at the tip discharge section is 0.1 MPa or more, preferably 1 MPa or more, and more preferably 2 MPa or more.

[0159] Examples of pelletizing methods include hot-cutting and strand-cutting methods, but are not particularly limited. Examples of cooling methods include air cooling, wind cooling, and water cooling. In the present invention, it is preferable to include a water cooling step. For example, it is preferable to cool to 20°C to 80°C, and more preferably to 30°C to 60°C.

[0160] (Additives, etc.) The recycled plastic obtained by the recycling method of the present invention may contain known additives. Examples of such additives include at least one antioxidant selected from the group consisting of phenolic and phosphorus-based agents; at least one lubricant selected from the group consisting of fatty acid amides, alkylene fatty acid amides, metal soaps, and esters; hindered amine-based weather stabilizers; waxes with an acid value of 5 mg KOH / g or less; and at least one antistatic agent selected from the group consisting of fatty acid sulfons and fatty acid esters.

[0161] The recycled plastic of the present invention may include virgin plastic as a raw material in addition to the laminate and packaging material described above. The virgin plastic added is of the same resin type as the first and second base materials. The virgin plastic may be added when pelletizing the laminate and packaging material, or when molding the pelletized recycled plastic of the present invention. It may also be added both when pelletizing and when molding the recycled plastic. As an example, the amount of virgin plastic used in combination when pelletizing the laminate and packaging material is in the range of laminate / packaging material:virgin plastic of 100:0 to 25:75 (mass ratio). As an example, the amount of virgin plastic used when molding the pelletized recycled plastic of the present invention is in the range of recycled plastic:virgin plastic of 100:0 to 25:75 (mass ratio).

[0162] (Crushing process) A crushing process for the laminate and packaging material may be provided prior to the melting and kneading process. In the crushing process, it is preferable to crush (including cutting) the laminate into small rectangular pieces with sides of about 1 to 50 mm, preferably 3 to 30 mm, and more preferably 3 to 15 mm. The crushing method may be so-called wet crushing, in which crushing is carried out in water or a washing solution, or dry crushing, in which crushing is carried out in an air atmosphere where no liquid such as a solvent is present.

[0163] While there are no particular limitations on the type of wet crusher, a wet crusher capable of simultaneously crushing, dispersing, mixing, and pumping solid material in a liquid is preferred. Specifically, a crusher having a mechanism for crushing solid material in a liquid using shear force and / or frictional force is preferred, as is a crusher having a mechanism for crushing and pumping plastic film. Examples of such wet crushers include wet crushing pumps, colloid mills, and grinders.

[0164] Dry crushers are not particularly limited, but examples include mycoloiders, mascoloiders, ball mills, power mills, pin mills, air-jet mills, shear friction mills, cutter mills, impact mills (hammer mills, ball mills), roll mills, homogenizers, ultrasonic crushers, etc.

[0165] (Washing Process) It is preferable that the crushed laminate pieces and packaging material pieces undergo a washing process before being sent to the melting and kneading process. In the washing process, a washing solution such as water or an aqueous detergent solution is placed in a washing container and stirred in the washing container to wash away organic matter (food residue, oil stains, etc.) and inorganic matter (sand, dust, etc.) adhering to the laminate. Next, the laminate pieces are transferred to a rinsing container that stores rinsing water and rinsed, then dehydrated and dried.

[0166] One method of dewatering is centrifugal dewatering. One method of drying is hot air drying. Dewatering and drying allow for adjustment of the moisture content of the laminate subjected to the melt-mixing process. This helps to avoid foaming during the production of recycled plastics. If air bubbles are generated during pellet production, the pressure in the cylinder changes, causing the extrusion amount and pressure to be inconsistent, which may result in irregular pellet shapes and dimensions. Furthermore, when manufacturing molded products through secondary molding using the manufactured pellets, surface irregularities are likely to occur, potentially degrading the surface condition of the molded product.

[0167] In one embodiment, dehydration and drying are carried out until the moisture content of the laminate used for the production of recycled plastic is 3% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, based on the total mass of the laminate.

[0168] <Molded Products> The recycled plastic of the present invention can be used as a raw material for various plastic products. Examples of plastic products include, but are not limited to, automobile parts such as bumpers and interior materials, components for home appliances, containers such as pallets and containers for transport, bottles, hangers, stationery, pots and cups, disposable cutlery, and toys. It can also be recycled as a film, or the recycled film can be molded and used as cushioning material when transporting fruits, etc., but is not limited to these. As a method for turning the recycled plastic of the present invention into a film to make a recycled film, known methods such as T-die molding, inflation molding, solution casting molding, and calendering can be used. As a method for molding the recycled film, known methods such as vacuum molding and hot press molding can be used.

[0169] The present invention will be described in more detail below with reference to specific synthesis examples and embodiments, but the present invention is not limited to these embodiments. In the following examples, "parts" and "%" represent "parts by mass" and "mass%", respectively, unless otherwise specified.

[0170] <Preparation of Polyol Composition (X)> (Polyol Composition (X-1)) In a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, moisture separator, etc., 400 parts by mass of propylene glycol, 80 parts by mass of trimethylolpropane, 700 parts by mass of adipic acid, and 0.1 parts by mass of titanium tetraisopropoxide were charged under nitrogen gas introduction. The mixture was gradually heated so that the temperature at the top of the rectification tube did not exceed 100°C, and the internal temperature was maintained at 250°C. The esterification reaction was terminated when the acid value became 1 mg KOH / g or less to obtain a polyester polyol. The hydroxyl value of the polyester polyol was 185 mg KOH / g. 6% by mass of amine-initiated polypropylene polyol (ADEKA Corporation, EDP-450, molecular weight 450, hydroxyl value 505 mg KOH / g) was added to this polyester polyol to obtain polyol composition (X-1). The hydroxyl value of the polyol composition (X-1) was 220 mgKOH / g.

[0171] (Polyol composition (X-2)) In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, etc., 31.4 parts of diethylene glycol, 9.6 parts of glycerin, 19.9 parts of isophthalic acid, 39.1 parts of adipic acid, and 0.01 parts of titanium tetraisopropoxide were added, and an esterification reaction was carried out at an internal temperature of 220°C. After the dehydration reaction, a polyester polyol with an acid value of 1.5 mg KOH / g was obtained. 80 parts of this polyester polyol were added to 20 parts of polypropylene triol (AGC Excenol 430, molecular weight 400, trifunctional, hydroxyl value 400 mg KOH / g) to obtain polyol composition (X-2).

[0172] (Polyol composition (X-3)) In a flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, water separator, etc., 13.3 parts of ethylene glycol, 28.5 parts of diethylene glycol, and 3.0 parts of trimethylolpropane were charged into the reaction vessel and stirred under nitrogen gas introduction, and heated to 100°C. At 100-110°C, 35.7 parts of adipic acid and 19.1 parts of isophthalic acid were added, and the mixture was gradually heated so that the temperature at the top of the rectification tube did not exceed 100°C, maintaining the internal temperature at 240°C, and stirred for 8 hours to obtain a polyester polyol.

[0173] 41.83 parts of the polyester polyol synthesized above, 8.00 parts of polyoxypropylene sorbitol ether (Sanyo Chemical Industries, Ltd., Sannix SP-750), and 0.17 parts of dimethylolpropionic acid were mixed to obtain polyol composition (X-3).

[0174] (Polyol composition (X-4)) 319 parts by mass of diethylene glycol, 121 parts by mass of 2-methyl-propanediol, and 55 parts by mass of trimethylolpropane were charged into a reaction vessel and heated to 80°C while stirring under a nitrogen gas stream until dissolved. Further stirring was carried out by adding 504 parts by mass of adipic acid to the reaction vessel and heating to 150°C to 240°C to carry out the esterification reaction. When the acid value became 5 mg KOH / g or less, the pressure in the reaction vessel was gradually reduced and the reaction was carried out at 1 mmHg or less and 200 to 220°C for 1 hour to obtain a polyester polyol resin having hydroxyl groups at both ends, with an acid value of 0.8 mg KOH / g and a molecular weight of approximately 660. This was used as polyol composition (X-4).

[0175] <Preparation of Polyisocyanate Composition (Y)> (Polyisocyanate Composition (Y-1)) 774.5 parts of toluene diisocyanate (TDI) were added to a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, and condenser, and heated to 40°C while stirring under a nitrogen gas stream. Then, 225.5 parts of bifunctional polyethylene glycol with a molecular weight of 200 were added carefully, taking care to avoid exothermic reactions, and the mixture was heated to 60°C. The reaction was continued at 60°C until the NCO% no longer changed, and 1.0 part of polyphosphate was added to terminate the reaction. Next, using a thin-film distillation apparatus, the TDI in the urethane prepolymer, which is the reaction product of TDI, was purified to 0.05% by mass of the solid content at a pressure of approximately 0.02 Torr and a temperature of 160°C until the TDI content was 0.05% by mass of the solid content, thereby obtaining polyether polyurethane polyisocyanate (C1-1) with an NCO% of 14.5%. This was used as polyisocyanate composition (Y-1).

[0176] (Polyisocyanate composition (Y-2)) 582.2 parts of toluene diisocyanate (TDI) were added to a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, and condenser, and heated to 40°C while stirring under a nitrogen gas stream. Then, 278.5 parts of bifunctional polyethylene glycol with a molecular weight of 400 and 139.3 parts of bifunctional polypropylene glycol with a molecular weight of 1000 were added carefully, taking care to avoid exothermic reactions, and the mixture was then heated to 60°C. The reaction was continued at 60°C until the NCO% no longer changed, and 1.0 part of polyphosphate was added to terminate the reaction. Next, using a thin-film distillation apparatus, the TDI in the urethane prepolymer, which is the reaction product of TDI, was purified to 0.05% by mass of the solid content at a pressure of approximately 0.02 Torr and a temperature of 160°C until the TDI content in the urethane prepolymer was 0.05% by mass of the solid content, thereby obtaining polyether polyurethane polyisocyanate (C1-2) with an NCO% of 9.4%. This was used as polyisocyanate composition (Y-2).

[0177] (Polyisocyanate composition (Y-3)) In a flask equipped with a stirrer, thermometer, and nitrogen gas inlet tube, 36 parts of 4,4'-diphenylmethane diisocyanate and 19 parts of 2,4'-diphenylmethane diisocyanate were charged and heated to 60°C while stirring under a nitrogen gas atmosphere. 11 parts of polypropylene glycol with a number average molecular weight of 400, 22 parts of polypropylene glycol with a number average molecular weight of 1000, and 11 parts of polypropylene glycol with a number average molecular weight of 2000 were added dropwise in several portions, and the mixture was stirred for 5 to 6 hours to complete the urethane reaction. A polyether polyurethane polyisocyanate (C1-3) with an NCO% of 13.5% was obtained. This was used as polyisocyanate composition (Y-3).

[0178] (Polyisocyanate composition (Y')) Seven parts of ethylene glycol and 35 parts of diethylene glycol were charged into a flask equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, water separator, etc., and heated to 80°C while stirring under a nitrogen gas stream. Further stirring was carried out by charging 36 parts of adipic acid and 22 parts of isophthalic acid into the reaction vessel, and the temperature was gradually increased so that the temperature at the top of the rectification tube did not exceed 100°C, maintaining the internal temperature at 250°C, and the esterification reaction was carried out. When the acid value became 12.0 mg KOH / g or less, the temperature was increased to 240°C, and the pressure inside the reaction vessel was gradually reduced, and the reaction was carried out at a rate of 40 Torr or less to obtain a polyester polyol having hydroxyl groups at both ends with an acid value of 1.0 mg KOH / g and a hydroxyl value of 84 mg KOH / g.

[0179] In a flask equipped with a stirrer, thermometer, and nitrogen gas inlet tube, 54 parts of a mixture of 2,2-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate were charged and heated to 60°C while stirring under a nitrogen gas stream. 23 parts of the polyester polyol synthesized above and 23 parts of polypropylene glycol with a number average molecular weight of 1000 were added dropwise in several portions. The mixture was further heated and maintained at an internal temperature of 70°C for 4 hours to carry out the urethane reaction, yielding a polyurethane polyisocyanate (polyisocyanate compound (C2)) with an NCO% of 14.7%. This was used as the polyisocyanate composition (Y').

[0180] <Evaluation of yellowing of adhesives> Adhesives for the examples and comparative examples were obtained using polyol composition (X) and polyisocyanate composition (Y) in the combinations shown in Tables 1 to 3. These were applied at a concentration of 10 g / m². ２ The degree of yellowing (Δb) when the coating is applied, cured, and heated at 225°C for 30 minutes is measured. ＊ ) was investigated. Note that Δb ＊ The b of the heated coating was measured using a spectrophotometer (SE2000, manufactured by Nippon Denshoku Industries) under the conditions of a viewing angle of 2° and light source C. ＊ Therefore, the b of the coating film before heating, measured under the same conditions ＊ This is the value obtained by subtracting b. ＊ L, which was standardized by the International Commission on Illumination in 1976. ＊ a ＊ b ＊ These are values ​​that represent the yellow and blue colors in a color system.

[0181] In the table, PEG refers to difunctional polyethylene glycol, and PPG refers to difunctional polypropylene glycol, with the numbers representing their respective molecular weights. For example, PEG-200 is polyethylene glycol with a molecular weight of 200 g / mol and a hydroxyl value of 560 mgKOH / g.

[0182]

[0183]

[0184]

[0185] <Evaluation of foreign matter> The adhesive from Example 11 was applied to the polyethylene film at a rate of 2.3 g / m². ２ The adhesive layer was applied and laminated to a polyethylene film. After aging at 40°C for two days, a laminate of polyethylene film / adhesive layer / polyethylene film was obtained. The obtained laminate was crushed using a crusher (Daiko Seiki, DAS-20) to obtain crushed laminate material. Similarly, the same polyethylene film used in the manufacture of the laminate was crushed using the crusher to obtain crushed virgin film material.

[0186] The laminated material and virgin film pulverized mixture were mixed in a 50:50 (mass ratio) and fed into the melting and kneading section of a twin-screw extruder (Kobe Steel KTX-30 twin-screw extruder). The melted and kneaded resin was extruded through a 100 μm filter, cooled by immersion in cold water, and then cut with a pelletizer to obtain recycled plastic pellets. The extruder's screw rotation speed was set to 300 rpm, the temperature to 230°C, the discharge rate to 8 kg / h, and the discharge pressure immediately after the start of extrusion was 1.3 to 2.2 MPa.

[0187] Recycled plastic pellets and virgin polyethylene resin pellets were mixed in a 50:50 (mass ratio) and fed into the molten section of an inflation extruder (AIKI Riotec ALM-IMF30 inflation molding unit). The molten resin was extruded from the inflation die and cooled and solidified with air to obtain a recycled film with a thickness of 25 μm. The extruder's screw rotation speed was set to 38 rpm and the temperature to 230°C.

[0188] Five 10cm x 10cm test pieces were cut from the obtained film. The number of foreign particles with a diameter of 200 μm or more present in the five test pieces was counted. Recycled films were prepared in the same manner for the adhesives of Example 12 and Comparative Examples 3 and 5, and the number of foreign particles was counted and summarized in Table 4.

[0189]

Claims

1. A solvent-free, two-component curing adhesive comprising a polyol composition (X) containing a polyol compound (A) and a polyisocyanate composition (Y) containing a polyisocyanate compound (C), wherein the polyol compound (A) comprises a polyol compound (A1) having a hydroxyl value of 45 mg KOH / g or more and 600 mg KOH / g or less, and an average number of functional groups of 1.8 or more and 3.0 or less, and the polyisocyanate compound (C) comprises a polyether polyurethane polyisocyanate (C1), and the polyol composition (X) and the polyisocyanate composition (Y) are used such that the urethane bond concentration after reaction is 2.0 mmol / g or more.

2. The two-component curing adhesive according to claim 1, used such that the urethane bond concentration is 6.0 mmol / g or less.

3. The polyol composition (X) and the polyisocyanate composition (Y) are used such that the total concentration of urethane bonds and urea bonds after the reaction is 2.5 mmol / g or more, as described in claim 1.

4. The two-component curing adhesive according to claim 3, used such that the total concentration of the urethane bond and the urea bond is 6.0 mmol / g or less.

5. The two-component curing adhesive according to claim 1, wherein the polyol compound (A1) comprises a polyether polyol.

6. The two-component curing adhesive according to claim 1, wherein the polyol compound (A1) comprises a polyester polyol.

7. A laminate comprising a first substrate, a second substrate, and an adhesive layer for bonding the first substrate and the second substrate, wherein the adhesive layer is a cured coating film of the two-component curing adhesive described in claim 1.

8. The laminate according to claim 7, wherein the first substrate and the second substrate contain the same type of resin.

9. A packaging material obtained by forming a bag from the laminate described in claim 7.

10. A method for recycling a laminate according to claim 7, wherein the laminate is melted and kneaded in a state in which the first substrate and the second substrate are bonded together by the adhesive layer.

11. A method for recycling a laminate according to claim 10, comprising melting and kneading the laminate with a virgin plastic made of the same resin type as the first substrate and the second substrate.

12. The method for recycling a laminate according to claim 10, wherein the melting and kneading are performed in an extrusion apparatus.

13. The method for recycling a laminate according to claim 10, wherein the laminate is crushed by a wet crusher or a dry crusher.

14. Recycled plastic obtained by the method for recycling laminates described in claim 10.

15. A plastic product molded from recycled plastic as described in claim 14.

16. A plastic product made from recycled plastic as described in claim 14 and virgin plastic of the same type of resin as the recycled plastic.

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