Primer composition for desorption, printed matter, and recycling method

Abstract

Provided is a primer composition for desorption that forms a primer layer for desorption in printed matter in which at least a plastic substrate, the primer layer for desorption, and a printed layer are laminated in the stated order. The primer composition for desorption contains at least a (meth)acrylic resin and an aqueous solvent mainly composed of water. The (meth)acrylic resin has an acid value of 10-90 mg KOH / g and a glass transition temperature of −30°C to 90°C. Thus, the problem is solved.

Description

Desorption primer composition, printed matter, and recycling method

[0001] The present invention relates to a primer composition that can be removed from a plastic substrate, a printed matter, and a recycling method.

[0002] In recent years, the marine plastic problem has become apparent, stemming from plastics discarded or dumped in the ocean breaking down in seawater and breaking down into tiny particles (microplastics). It is feared that these microplastics may enter the bodies of marine organisms, become concentrated, and impact the health of seabirds and humans through the food chain. Recycling is one way to address this issue. Improving the recycling rate of resources such as flexible packaging and plastic bottles will prevent plastic from entering the ocean. However, current recycling methods pose a challenge: printed layers on plastic substrates do not detach during the recycling process and become mixed into the plastic, resulting in a deterioration in color and physical properties, thereby reducing the value of the recycled plastic. Solving this issue by making the printed layer detachable from the plastic substrate during the recycling process could improve the value of recycled plastics. This could potentially lead to the entry of new recyclers and the establishment of municipal waste sorting and collection systems, thereby mitigating the marine plastic problem. Therefore, there is a need for the development of materials capable of forming a detachable printed layer from the plastic substrate during the recycling process. On the other hand, the printing layer needs to have the blocking resistance required of conventional inks, as well as the ability to not come off when rubbed or scratched during normal use, or when tape is peeled off. It has been difficult to achieve both this and the ability to be releasable during the recycling process.

[0003] Furthermore, materials for forming printing layers that are widely used on plastic substrates are being replaced with toluene-free and methyl ethyl ketone (MEK)-free materials in consideration of their impact on worker health and the environment, and therefore materials that solve the above-mentioned problems must also be developed with this in mind.

[0004] Prior art techniques have been disclosed in which a coating layer containing styrene-maleic acid resin, rosin-maleic acid resin, or acrylic acid copolymer resin is formed between printed layers on a heat-shrinkable PET film, and the coating layer is then removed using alkaline water (Patent Documents 1 and 2). However, these techniques remain solvent-based, and water-based methods are needed from an environmental perspective. Examples have also been disclosed in which the top-coat ink layer is deinked using a water-based resin as the coating layer (Patent Documents 3 and 4). However, Patent Document 3 has the problem of limiting the ink to activation energy-curable inks, and Patent Document 4 uses an aqueous urethane resin primer, which leaves the problem of low coating film resistance. In addition, the coating is said to be removable even at low temperatures and with strong alkalinity. In other words, there is the problem of the coating film removing under normal usage conditions, such as when strong alkaline substances such as detergents adhere to printed materials in daily life.

[0005] Japanese Patent Application Laid-Open No. 2003-84670 Japanese Patent Application Laid-Open No. 2004-240029 Japanese Patent No. 7404578 Japanese Patent Application Laid-Open No. 2017-114930

[0006] In view of the above, an object of the present invention is to provide a deinkable primer composition that exhibits printing performance (adhesion, abrasion resistance, scratch resistance, blocking resistance, and shrinkage suitability) equivalent to that of conventional inks on general-purpose plastic substrates, while at the same time having alkali resistance at low temperatures and being able to achieve desorption performance at high temperatures and low alkali concentrations.

[0007] As a result of intensive research by the present inventors to solve the above problems, they found that the above problems can be solved by a detachment primer composition that forms a detachment primer layer of a printed matter in which at least a plastic substrate, a detachment primer layer, and a printed layer are laminated in this order, the detachment primer composition containing at least a (meth)acrylic resin and an aqueous solvent containing water as a main component, and the (meth)acrylic resin has an acid value of 10 to 90 mgKOH / g and a glass transition temperature of -30°C to 90°C, and thus completed the present invention.

[0008] That is, the present invention provides a detachment primer composition that forms a detachment primer layer of a printed matter in which at least a plastic substrate, a detachment primer layer, and a printed layer are laminated in this order, the detachment primer composition containing at least a (meth)acrylic resin and an aqueous solvent containing water as a main component, and the (meth)acrylic resin has an acid value of 10 to 90 mgKOH / g and a glass transition temperature of −30° C. to 90° C.

[0009] The present invention also provides a printed article having at least a plastic substrate, a detachable primer layer, and a printed layer laminated in this order, the printed article having a detachable primer layer formed from the above-mentioned detachable primer composition.

[0010] Furthermore, the present invention provides a recycling method for recovering a plastic substrate from which a printed layer has been detached from a printed matter in which at least a plastic substrate, a detachment primer layer, and a printed layer are laminated in this order, wherein the detachment primer layer is formed from a detachment primer composition, and the printed matter is immersed in an alkaline aqueous solution to detach the printed layer from the plastic substrate.

[0011] A printed matter including a detachable primer layer formed by the detachable primer composition of the present invention exhibits printing performance (adhesion, abrasion resistance, scratch resistance, blocking resistance, and shrinkage suitability) equivalent to that of conventional inks, even on general-purpose plastic substrates, while at the same time having alkali resistance at low temperatures and being able to achieve detachment performance at high temperatures and low alkali concentrations.

[0012] The following will describe in detail the components of the release primer composition of the present invention and the printed matter containing the same.

[0013] In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate.

[0014] <Removal Primer Composition> The detachment primer composition of the present invention is a composition that forms a detachment primer layer. That is, the detachment primer layer is a coating layer of the detachment primer composition of the present invention. The detachment primer layer is formed on a plastic substrate, and by laminating a printed layer on the detachment primer layer, the printed layer can be detached from the plastic substrate. The detachment primer composition contains at least a (meth)acrylic resin and an aqueous solvent containing water as a main component, and the (meth)acrylic resin has an acid value of 10 to 90 mgKOH / g and a glass transition temperature of -30°C to 90°C.

[0015] Incidentally, a resist ink composition can be mentioned as an example of a composition that is removed from a substrate in the same manner as in the present invention. However, the resist ink composition is intended to process the substrate by removing a coating film from the substrate in advance, leaving a portion of the coating film remaining. The resist ink composition has a fundamentally different use and purpose from the removal primer composition of the present invention, which is intended to remove the entire laminated printed layer and recycle the substrate, and therefore does not fall under the well-known technology of the present invention.

[0016] Furthermore, the detachable primer composition of the present invention has the function of adhering to a printed layer made of ink and peeling off from a plastic substrate under certain conditions, and its use is different from that of an ink composition that is required not to peel off from the substrate, and its purpose is contradictory.

[0017] <(Meth)acrylic Resin> The detachment primer composition of the present invention contains a (meth)acrylic resin. Here, the (meth)acrylic resin refers to a resin having a structural unit derived from a (meth)acrylic acid ester monomer, and examples thereof include acrylic resin, styrene-acrylic resin, polyester-acrylic resin, urethane-acrylic resin, vinyl chloride-vinyl acetate copolymer-acrylic resin, silicone-acrylic resin, acrylamide resin, and epoxy-acrylic resin. In other words, the (meth)acrylic resin refers to a resin obtained by (co)polymerizing a (meth)acrylic acid ester as an essential monomer, as needed, together with other polymerizable unsaturated group-containing compounds.

[0018] Examples of the (meth)acrylic acid ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-pentafluoropropyl (meth)acrylate, and perfluoro Examples of the (meth)acrylate monomer include cyclohexyl (meth)acrylate, glycidyl (meth)acrylate, allyl glycidyl ether, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, (meth)acrylamide, N-monoalkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, N-methylol (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, 2-aziridinylethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, acrolein, diacetone (meth)acrylamide, and acetoacetoxyethyl (meth)acrylate. The (meth)acrylic acid ester monomer may be used alone or in combination of two or more.

[0019] Examples of the polymerizable unsaturated group-containing compound include vinyl monomers such as vinyl acetate, vinyl propionate, vinyl versatate, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, (meth)acrylonitrile, styrene, α-methylstyrene, divinylstyrene, isoprene, chloroprene, butadiene, ethylene, tetrafluoroethylene, vinylidene fluoride, and N-vinylpyrrolidone. The polymerizable unsaturated group-containing compound may be used alone or in combination of two or more.

[0020] The (meth)acrylic resin may also be reacted with a self-crosslinking component. That is, the (meth)acrylic resin may be a self-crosslinking type. Examples of the self-crosslinking component include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, and aziridine compounds. The content of the self-crosslinking component is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 6 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the solid content of the (meth)acrylic resin. When the content of the self-crosslinking component is within the above range, the storage stability of the release primer composition may be improved.

[0021] The (meth)acrylic resin can be produced, for example, by polymerizing various monomers in the presence of a polymerization initiator at a temperature range of 50°C to 180°C, more preferably 80°C to 150°C. Examples of the polymerization method include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. In addition, when the (meth)acrylic resin is a copolymer, it may be a random copolymer, a block copolymer, a graft copolymer, or the like, from the viewpoint of the polymerization mode.

[0022] The weight-average molecular weight of the (meth)acrylic resin is preferably 2,000 to 1,500,000 from the viewpoint of achieving both releasability and adhesion to plastic substrates, etc. The weight-average molecular weight of the (meth)acrylic resin can be determined by gel permeation chromatography (GPC).

[0023] The (meth)acrylic resin may be used as an aqueous resin after a neutralization reaction. The aqueous resin may be in the form of an emulsion or a solution. The (meth)acrylic resin of the present invention is preferably a (meth)acrylic resin emulsion having a core-shell structure. The core-shell type emulsion refers to a state in which a first polymer is dispersed in an aqueous medium by a second polymer, and usually, the second polymer is present at the outermost part of the resin particles to form a shell portion, and part or all of the first polymer forms a core portion.

[0024] The content of the (meth)acrylic resin in the detachment primer composition of the present invention is preferably in the range of 5% by mass to 70% by mass, and more preferably in the range of 10% by mass to 50% by mass, relative to the total amount of the detachment primer composition.

[0025] The content of the (meth)acrylic resin in the detachment primer composition of the present invention is preferably 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more, based on the total solids content of the detachment primer composition. Within the above range, excellent adhesion to plastic substrates and a suitable viscosity as a detachment primer composition can be obtained when forming a printed layer using the detachment primer composition of the present invention, resulting in good work efficiency during production and print layer formation, and enabling uniform detachment of the printed layer during deinking treatment. Furthermore, inks generally contain pigments and many additives from the perspectives of image formation and coating film properties, and therefore detachment properties vary significantly depending on various factors such as the type and concentration of the pigment and the print thickness. By overcoating ink on the detachment primer composition, the printed layer can be suitably detached regardless of the detachability of the ink itself. In particular, when 50% by mass or more of the solids content of the primer composition is a (meth)acrylic resin component, uniform detachment occurs during alkali treatment, regardless of the pigment type and concentration of the overcoated ink, the print thickness, etc., and the overcoated ink layer can be efficiently detached.

[0026] <Glass Transition Temperature of (Meth)acrylic Resin> The (meth)acrylic resin of the present invention is a (meth)acrylic resin having a glass transition temperature (Tg) of -30°C or higher and 90°C or lower. If the glass transition temperature is lower than -30°C, the abrasion resistance, scratch resistance, and blocking resistance may deteriorate. If the glass transition temperature is higher than 90°C, the adhesion, detachment property, and shrinkage suitability may deteriorate. From the viewpoint of more effectively improving the adhesion, abrasion resistance, scratch resistance, blocking resistance, detachment property, and shrinkage suitability, the glass transition temperature (Tg) of the (meth)acrylic resin is more preferably -30°C or higher and 50°C or lower, even more preferably -30°C or higher and 20°C or lower, and even more preferably -30°C or higher and 0°C or lower.

[0027] The glass transition temperature (Tg) refers to the so-called calculated glass transition temperature, and refers to a value calculated by the following method: (Equation 1) 1 / Tg(K)=(W1 / T1)+(W2 / T2)+...(Wn / Tn) (Equation 2) Tg(°C)=Tg(K)-273 In Equation 1, W1, W2,...Wn represent the mass% of each monomer with respect to the total mass of the monomers used in producing the polymer, and T1, T2,...Tn represent the glass transition temperature (K) of the homopolymer of each monomer. The values ​​of T1, T2,...Tn are those described in Polymer Handbook (Fourth Edition, edited by J. Brandrup, E.H. Immergut, and E.A. Grulke). Furthermore, for the homopolymers of each monomer whose glass transition temperature is not described in the Polymer Handbook, the glass transition temperature was measured using a differential scanning calorimeter "DSCQ-100" (manufactured by TA Instrument Co., Ltd.) according to a method conforming to JIS K 7121. Specifically, the polymer was subjected to vacuum suction to completely remove the solvent, and the change in heat quantity was measured in the range of -100°C to +200°C at a heating rate of 20°C / min, and the point where a straight line equidistant in the vertical direction from the extended straight line of each baseline intersects with the curve of the stepwise change in the glass transition was taken as the glass transition temperature.

[0028] <Acid Value of (Meth)acrylic Resin> The (meth)acrylic resin of the present invention has an acid value of 10 to 90 mgKOH / g. If the acid value (also referred to as "AV") of the (meth)acrylic resin is 10 mgKOH / g or more, the release property can be more effectively improved, and if it is 90 mgKOH / g or less, the alkali resistance, adhesion, and shrinkage suitability, especially at low temperatures, can be more effectively improved. From the same viewpoint, the acid value of the (meth)acrylic resin is preferably 85 mgKOH / g or less, more preferably 65 mgKOH / g or less, and even more preferably 50 mgKOH / g or less. The acid value refers to the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 g of resin.

[0029] In this embodiment, the (meth)acrylic resin is preferably an acrylic resin (i.e., a resin obtained by polymerizing substantially only (meth)acrylic acid ester monomers) or a styrene-acrylic resin (i.e., a resin obtained by copolymerizing a styrene monomer and a (meth)acrylic acid ester monomer), and more preferably an acrylic resin. That is, the (meth)acrylic resin of the present invention is preferably a homopolymer or copolymer of (meth)acrylate or a copolymer obtained by copolymerizing a styrene monomer and a (meth)acrylic acid ester monomer, and more preferably a homopolymer or copolymer of (meth)acrylate. In this case, adhesion, blocking resistance, heat resistance, water-rubbing resistance, and alcohol resistance can be more effectively improved.

[0030] The (meth)acrylic resin of the present invention can be made aqueous by introducing a carboxyl group into the molecule and neutralizing it with a basic compound, or by using a known emulsifier or polymer to form a protective colloid. As the basic compound, an amine compound is preferred, and ammonia is preferably used.

[0031] The (meth)acrylic resin of the present invention is preferably alkali-insoluble from the viewpoint of alkali resistance at room temperature. Here, alkali-insolubility is determined based on the following method. 3 g of the resin component (solid content) is added to 100 g of a 2% by mass aqueous sodium hydroxide solution heated to 70°C, stirred for 5 minutes, and then left to stand for 1 day while maintaining the temperature of the aqueous solution at 70°C. After 1 day, the aqueous solution is adjusted to room temperature (25°C), and the NTU (Nephelometric Turbidity Unit) is measured using a Lovibond TB 300 IR turbidity meter (manufactured by Tintmaker). The aqueous solution is also filtered through Whatman Filter Paper No. 1 (manufactured by Cytiva), and the remaining resin component and precipitates resulting from the solution being cooled to room temperature are visually inspected. If the turbidity is 50 NTU or more or if there is residual resin, the resin component is judged to be alkali-insoluble.If the turbidity is less than 50 NTU and there is no residual resin or precipitates due to being cooled to room temperature, the resin component is judged to be alkali-soluble.

[0032] <Aqueous Solvent> The release primer composition of the present invention contains an aqueous solvent containing water as a main component. Here, "containing water as a main component" means that 50 mass % or more of the total amount of the medium in the release primer is water. Note that the medium also includes media such as water and solvents contained in the (meth)acrylic resin and other components. Examples of the aqueous solvent used in this embodiment include water alone and organic solvents that are miscible with water. Examples of the organic solvent include various organic solvents such as alcohols (e.g., methanol, ethanol, propanol, butanol, isopropyl alcohol), ketones (e.g., acetone, methyl ethyl ketone, cyclohexanone), glycol ethers (e.g., 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, dipropylene glycol (mono-, di-) methyl ether, etc. The aqueous solvent may be used alone or in combination of two or more.

[0033] The aqueous solvent is preferably contained in the range of 50% by mass to 95% by mass, and more preferably in the range of 65% by mass to 90% by mass, based on the total amount of the detachment primer composition.

[0034] <Other Components> The detachment primer composition of the present invention may contain other components. Examples of such other components include other resins; various additives such as film-forming aids, crosslinking agents, curing accelerators, plasticizers, antistatic agents, waxes, light stabilizers, flow modifiers, leveling agents, rheology control agents, antifoaming agents, antiblocking agents, infrared absorbers, ultraviolet absorbers, antioxidants, extender pigments, fragrances, flame retardants, and photocatalytic compounds; and colorants such as dyes, inorganic pigments, and organic pigments. The detachment primer composition of the present invention preferably contains 5% by mass to 70% by mass of a (meth)acrylic resin and 50% by mass to 95% by mass of an aqueous medium relative to the total amount of the detachment primer composition. Therefore, from the viewpoint of ensuring the content of the (meth)acrylic resin, it is preferable that the detachment primer composition of the present invention does not contain a colorant.

[0035] Examples of the other resins include cellulose-based resins, urethane resins, polyamide resins, vinyl chloride-vinyl acetate copolymer resins, ketone resins, polyester resins, rosin-modified maleic acid resins, rosin-modified fumaric acid resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, cyclized rubber, chlorinated rubber, butyral resins, and petroleum resins; radical copolymer resins such as styrene-maleic acid (anhydride) resins and terpene-maleic acid (anhydride) resins obtained by copolymerizing polymerizable monomers such as polymerizable monomers having a carboxyl group (e.g., itaconic acid, maleic acid, fumaric acid, cinnamic acid, or acid anhydrides thereof), polymerizable monomers having a sulfonic acid group (e.g., sulfonated styrene), and polymerizable monomers having a sulfonamide group (e.g., vinylbenzenesulfonamide); and acid-modified polyolefin resins. These may be used singly or in combination.

[0036] (Production of Detachment Primer Composition) The method for producing the detachment primer composition of this embodiment is not particularly limited, but for example, the detachment primer composition can be obtained by dispersing a mixture to which additives and the like have been added as needed in the aqueous solvent, and then adding a (meth)acrylic resin, an aqueous solvent, and additives such as a surfactant as needed, and stirring and mixing. For the above-mentioned dispersion and stirring and mixing, a dispersing machine such as a bead mill, Eiger mill, sand mill, gamma mill, or attritor that is commonly used in the production of inks for flexographic printing or gravure printing can be used.

[0037] When the detachment primer composition of the present invention is applied by flexographic printing or gravure printing, the viscosity thereof may be 7 to 50 seconds, more preferably 12 to 40 seconds, at 25°C using a Zahn Cup #3 manufactured by Rigo Co., Ltd. Furthermore, the surface tension of the detachment primer composition at 25°C is preferably 25 to 50 mN / m. The lower the surface tension of the detachment primer composition, the better the wettability of the detachment primer composition to plastic substrates such as films. On the other hand, if the surface tension exceeds 50 mN / m, the wettability of the detachment primer composition to plastic substrates such as films decreases, which is likely to cause cissing. From the same viewpoint, the surface tension of the detachment primer composition at 25°C is more preferably 33 mN / m or more, and more preferably 43 mN / m or less.

[0038] <Removal Primer Layer> The detachment primer composition of the present invention is applied to a plastic substrate and then dried to form a detachment primer layer. That is, the detachment primer layer is formed by the detachment primer composition of the present invention. In other words, the detachment primer layer is a coating layer of the detachment primer composition of the present invention. As described below, a printed layer made of printing ink can be formed on the detachment primer layer. The detachment primer layer can be easily detached by treatment with an alkaline aqueous solution whose liquid temperature is adjusted to a certain temperature or higher. Since the detachment primer layer is easily detached from the plastic substrate, the printed layer formed on the detachment primer layer can also be easily removed from the plastic substrate. Note that a detailed description of the method for detaching the detachment primer layer will be given later.

[0039] The release primer composition of the present invention can be applied or coated onto a plastic substrate using a known printing method such as gravure printing, flexographic printing, etc. Known printing methods include, in addition to gravure printing and flexographic printing, a T-die coater, a lip coater, a knife coater, a curtain coater, an inkjet coater, a bar coater, a roll coater, a spray coater, a comma coater, a reverse roll coater, a direct gravure coater, a reverse gravure coater, an offset gravure coater, a roll kiss coater, a reverse kiss coater, a kiss gravure coater, a reverse kiss gravure coater, an air doctor coater, a wire bar coater, a dip coater, a blade coater, a brush coater, a die slot coater, an offset printing machine, a screen printing machine, etc., or a combination of two or more coating methods can be used. When applying, the coating is diluted with a diluting solvent, for example, a mixture of water and an alcohol-based organic solvent such as ethyl alcohol, isopropyl alcohol, or normal propyl alcohol, to a viscosity and concentration suitable for various printing methods such as gravure printing and flexographic printing, and is supplied to each printing unit either alone or in a mixture.

[0040] Furthermore, the method for applying the detachment primer composition onto the plastic substrate can be an inline coating method in which the detachment primer composition is applied during a stretching process (for example, a biaxial stretching process) of the plastic substrate, and then a further stretching process is performed, or it can be an offline coating method in which the detachment primer composition is applied and dried after the stretching process (for example, a biaxial stretching process) of the plastic substrate to form a primer layer.

[0041] The thickness of the detachment primer layer formed by gravure printing, flexographic printing or the like using the detachment primer composition of the present invention is, for example, preferably 10 μm or less, more preferably 5 μm or less.

[0042] <Printed matter> The printed matter in the present invention refers to a laminate in which a plastic substrate, a removable primer layer, and a printed layer are laminated in this order. The printed matter made of this laminate may contain other layers or may contain multiple printed layers. The removable primer layer may also be simply referred to as a "primer layer."

[0043] When forming a primer layer on a plastic substrate in producing a printed matter made of the above laminate, as explained in the section above (Removable primer layer), the primer layer may be formed by an in-line coating method in which the detachable primer composition of the present invention is applied during the stretching process of a film that is a plastic substrate, and then a stretching process is carried out, or the primer layer may be formed by an off-line coating method in which the detachable primer composition of the present invention is applied after the stretching process of a film that is a plastic substrate, and then dried to form a primer layer.

[0044] The printed matter of the present invention can be used as a packaging material. Examples of packaging materials include packaging bags, shrink labels, and various shrink labels such as printed wrap film. When used as a packaging bag, the printed matter of the present invention is filled with contents through its opening, and the opening is then heat-sealed to produce a product using the packaging material. The contents to be filled are not particularly limited, and examples include foods such as confectioneries, staples, processed agricultural products, processed livestock products, processed seafood products, fruits, vegetables, cooked foods, and dairy products; pharmaceuticals; cosmetics; detergents; vacuum insulation materials; and batteries. When used as a shrink label, the printed matter is tubing-wrapped by means of welding or sealing, attached to a PET container or glass container, and then heated to a predetermined shrinkage temperature to heat-shrink and adhere to the container. When used as a wrap film, the printed matter is used for packaging irregularly shaped items, bundling products, and guaranteeing packaging.

[0045] <Plastic Substrate> Examples of the plastic substrate include a base film, a sealant film, a metal-deposited unstretched film, a metal-deposited stretched film, and a transparent metal-deposited stretched film.

[0046] Examples of the substrate film include polyethylene terephthalate (PET) films (OPET: biaxially oriented polyethylene terephthalate film, etc.), polybutylene terephthalate (PBT) films, polystyrene films, polyamide films, nylon films, polyacrylonitrile films, polyolefin films such as polyethylene films (OPE: biaxially oriented polyethylene film, LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film) and polypropylene films (CPP: unoriented polypropylene film, OPP: biaxially oriented polypropylene film), polyvinyl alcohol films, ethylene-vinyl alcohol copolymer films, cellophane, etc. The substrate film may be coated for purposes such as gas barrier properties. Commercially available coated substrate films include K-OPP film and K-PET film.

[0047] A shrinkable film may be used as the substrate film. Examples of such shrinkable films include shrinkable polypropylene, shrinkable polyvinyl chloride, shrinkable polystyrene, shrinkable polyethylene terephthalate, and hybrid polystyrene (a hybrid film of polystyrene and polyethylene terephthalate, etc.). The (meth)acrylic resin of the present invention has good conformability to shrinkable films, and therefore the effects of the present invention are easily achieved. Furthermore, the detachment primer composition of the present invention is less likely to become cloudy when shrunk by hot water, steam, or hot air, and has good shrinkability. From the above perspectives, the plastic substrate of the present invention is preferably a shrinkable film. Furthermore, the surface of polystyrene is easily dissolved by the solvent in the ink, and the ink and the shrinkable film are firmly adhered to each other, making them less likely to detach. On the other hand, laminating a detachment primer layer formed from the detachment primer composition of the present invention between a printed layer and a shrinkable film can reduce direct contact between the shrinkable film and the printed layer, thereby reducing the influence of the ink solvent. Therefore, good detachment performance can be achieved even if the plastic substrate is a shrinkable film with poor detachment properties. Therefore, the plastic substrate of the present invention is more preferably a shrinkable film containing polystyrene, and more specifically, shrinkable polystyrene or hybrid polystyrene.

[0048] Examples of the sealant film include CPP film (unstretched polypropylene film) and LLDPE film (linear low-density polyethylene resin film). The metal-vapor-deposited unstretched film can be a VM-CPP film, which is a CPP film that has been vapor-deposited with a metal such as aluminum. The metal-vapor-deposited stretched film can be a VM-OPP film, which is an OPP film that has been vapor-deposited with a metal such as aluminum. The transparent vapor-deposited stretched film can be an OPP film, a PET film, a nylon film, or the like that has been vapor-deposited with silica or alumina. A film with a coating applied to the vapor-deposited layer can also be used for the purpose of protecting the inorganic vapor-deposited layer of silica or alumina. Vapor-deposited films such as metal-vapor-deposited unstretched film, metal-vapor-deposited stretched film, and transparent vapor-deposited stretched film can be described as a substrate film having a vapor-deposited layer.

[0049] Furthermore, films formed from materials containing biomass-derived components can also be used as plastic substrates. Biomass films are commercially available from various companies, and films and sheets such as those listed in the list of biomass-certified products published by the Japan Organics Resources Association can also be used. A specific well-known film is made from biomass-derived ethylene glycol. Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol to ethylene oxide using a conventionally known method to produce ethylene glycol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be used.

[0050] Alternatively, products using biomass raw materials classified by the degree of biomass plastic specified by ISO 16620 or ASTM D6866 are also on the market. １２Radioactive carbon 14C is present at a rate of one per atom, and this rate remains the same even in atmospheric carbon dioxide, so this rate remains the same even in plants that have fixed carbon dioxide through photosynthesis. Therefore, 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, the plant-derived resin content in the resin, i.e., the biomass plastic content, can be determined by measuring the concentration of radioactive carbon 14C in the resin using an accelerator mass spectrometer. Examples of plant-derived low-density polyethylenes that are biomass plastics with a biomass plastic content of 80% or more, preferably 90% or more, as specified by ISO 16620 or ASTM D6866, include products manufactured by Braskem under the trade names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681." Films made from these materials can be suitably used.

[0051] For example, biomass polyolefin films, such as biomass polyethylene films and biomass polyethylene-polypropylene films, containing ethylene resins made from biomass-derived ethylene glycol are known as alternatives to conventional polyolefin films made from petroleum-based raw materials. The ethylene resin is not particularly limited except that the biomass-derived ethylene glycol is used as part of the raw material. Examples of the ethylene resin include ethylene homopolymers and copolymers of ethylene and α-olefins containing ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units). These can be used alone or in combination of two or more. The α-olefin constituting the copolymer of ethylene and α-olefin is not particularly limited, and examples include α-olefins having 4 to 8 carbon atoms, such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins, such as low-density polyethylene resins, medium-density polyethylene resins, and linear low-density polyethylene resins, can be used. Among these, from the viewpoint of making it more difficult for damage such as holes or tears to occur even when films are rubbed against each other, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene, or a copolymer of ethylene and 1-octene) is preferred, and a density of 0.910 to 0.925 g / cm ３ More preferred is a linear low density polyethylene resin in which

[0052] The biomass film may be a laminate of multiple biomass films, or may be a laminate of a conventional petroleum-based film and a biomass film.

[0053] The plastic substrate may be one that has been subjected to some kind of surface treatment, for example, a physical treatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, or flame treatment, a chemical treatment such as oxidation treatment using chemicals, or other treatments.

[0054] The plastic substrate can be produced from the above-mentioned resin by a conventionally known film-forming method such as extrusion, cast molding, T-die, cutting, inflation, etc. The film may be an unstretched film, or may be one that has been stretched uniaxially or biaxially using a tenter system, a tubular system, or the like, from the viewpoint of film strength, dimensional stability, and heat resistance.

[0055] The plastic substrate may contain additives as needed. Specifically, plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added for the purpose of improving or modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, mold releasability, flame retardancy, mildew resistance, electrical properties, strength, etc. The amount of additive added is adjusted within a range that does not affect other properties or recyclability.

[0056] The thickness of the plastic substrate is not particularly limited and may be appropriately selected in the range of 0.1 to 300 μm from the viewpoints of moldability and transparency. The thickness is preferably in the range of 0.3 to 100 μm. If the thickness of the substrate is 0.1 to 300 μm, good strength and processing stability can be obtained.

[0057] The plastic substrate may have, as other layers, a coating layer that imparts functions such as release properties and antistatic properties, a barrier resin layer that imparts barrier properties, or a heat-resistant resin layer that imparts heat resistance. In this case, the other layer may be between the plastic substrate and the primer layer, or between the primer layer and the printing layer, or the other layer may be on the outermost surface of the printed product, i.e., the surface of the printed product facing the plastic substrate and / or the surface of the printing layer.

[0058] <Printed Layer> The printed layer is a layer on which characters, figures, symbols, other desired designs, etc. are printed, and is formed from printing ink. The printing ink and printing method are not particularly limited, and known printing inks and printing methods can be used. Printing inks include water-based inks, organic solvent-based inks, UV inks, etc., depending on the medium used. The printing ink that forms the printed layer of the present invention is preferably a water-based ink or an organic solvent-based ink, from the viewpoints of adhesion to the plastic substrate, followability when the plastic substrate shrinks, and prevention of ink cracking.

[0059] As for the printing method, printing inks using gravure printing, flexographic printing, lithographic offset printing, inkjet recording printing, etc. are often used for the film used as the substrate. Printing inks that combine these printing methods with methods of curing using active energy rays such as ultraviolet (UV), LED, and electron beam (EB), or methods of curing using heat, etc., are also used. Specific examples include gravure printing inks and flexographic printing inks (in some industries, gravure printing inks and flexographic printing inks are sometimes referred to as liquid printing inks), ultraviolet-curable inks for lithographic offset printing, electron-beam-curable inks for lithographic offset printing, ultraviolet-curable inks for inkjet recording printing, and electron-beam-curable inks for inkjet recording printing.

[0060] The ink may contain a colorant as an essential component, or may be a so-called clear ink or varnish that does not substantially contain a colorant. The printed layer may also be composed of multiple layers. Specifically, the layers may be: printed layer (white)-printed layer (color); printed layer (white)-printed layer (white)-printed layer (color); printed layer (white)-printed layer (color)-printed layer (clear / varnish); printed layer (white)-printed layer (white)-printed layer (color)-printed layer (clear / varnish); etc. The following describes the liquid printing inks that are most commonly used for printing on films.

[0061] (Liquid Printing Ink) Liquid printing inks are used as gravure printing inks and flexographic printing inks, and are broadly classified into organic solvent-based liquid printing inks, which contain an organic solvent as the main solvent, and water-based liquid printing inks, which contain water as the main solvent. As the printing ink for forming the printed layer of the present invention, organic solvent-based liquid printing inks and water-based liquid printing inks are preferred.

[0062] (Organic Solvent-Based Liquid Printing Ink) Organic solvent-based liquid printing ink is prepared by dispersing a mixture containing a binder resin, an organic solvent medium, a dispersant, an antifoaming agent, etc., in a disperser to obtain a pigment dispersion. The resulting pigment dispersion is then mixed with a resin, an organic solvent medium, and, if necessary, additives such as a leveling agent, followed by stirring and mixing. The disperser used for production is a bead mill, Eiger mill, sand mill, gamma mill, attritor, or the like, which are commonly used in the production of gravure and flexographic printing inks.

[0063] The ink viscosity of the organic solvent-based liquid printing ink, whether used as a gravure printing ink or a flexographic printing ink, is preferably in the range of 10 mPa·s or more from the viewpoint of preventing pigment sedimentation and adequate dispersion, and 1,000 mPa·s or less from the viewpoint of workability during ink production and printing. The viscosity is measured at 25°C using a B-type viscometer manufactured by Tokimec Co., Ltd.

[0064] The viscosity of the ink can be adjusted by appropriately selecting the types and amounts of raw materials used, binder resin, pigment, organic solvent, etc. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the pigment in the ink.

[0065] The organic solvent-based liquid printing ink has excellent adhesion to various substrates and can be used for printing on paper, synthetic paper, thermoplastic resin films, plastic products, steel plates, etc., and can be used as an ink for gravure printing using a gravure printing plate made by electronic engraving or the like, or for flexographic printing using a flexographic printing plate made by a resin plate or the like.

[0066] The thickness of the liquid printing ink film formed by gravure printing or flexographic printing using the organic solvent-based liquid printing ink is, for example, 10 μm or less, and preferably 5 μm or less.

[0067] (Binder Resin (A)) Examples of the binder resin (A) used in the organic solvent-based liquid printing ink include cellulose-based resins such as nitrocellulose, cellulose acetate propionate (CAP) and cellulose acetate butyronate (CAB), and other cellulose-based resins, polyamide-based resins, urethane-based resins, acrylic resins, vinyl chloride-based resins such as vinyl chloride-vinyl acetate copolymer resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, and polyvinyl chloride resins, polyester resins, alkyd resins, rosin-based resins, rosin-modified maleic acid resins, ketone resins, cyclized rubbers, chlorinated rubbers, polyvinyl butyral resins, and petroleum resins.

[0068] Among these, cellulose resins, polyamide resins, urethane resins, acrylic resins, vinyl chloride resins, and polyvinyl butyral resins are preferred. It is particularly preferred that the binder resin contains at least two types of resins. The preferred combinations are urethane resin / vinyl chloride resin, urethane resin / cellulose resin, polyamide resin / cellulose resin, acrylic resin / cellulose resin, vinyl chloride resin / cellulose resin, and urethane resin / polyvinyl butyral resin, and the total content of the two resins in 100% by mass of the binder resin (A) is preferably 80 to 100% by mass, and most preferably 90 to 100% by mass.

[0069] Furthermore, the mass ratio of urethane resin / vinyl chloride resin, urethane resin / cellulose resin, polyamide resin / cellulose resin, acrylic resin / cellulose resin, and vinyl chloride resin / cellulose resin is preferably 95 / 5 to 20 / 80, more preferably 90 / 10 to 50 / 50. This combination provides excellent abrasion resistance, blocking resistance, heat resistance, oil resistance, and other basic properties desired for a coating agent.

[0070] (Curing Agent) A curing agent may be used in combination with the binder resin (A). A curing agent generally used in organic solvent-based gravure printing inks may be used as the curing agent, but the most commonly used curing agent is an isocyanate-based curing agent. From the viewpoint of curing efficiency, the amount of the isocyanate compound added is preferably in the range of 0.3% by mass to 10.0% by mass, and more preferably 1.0% by mass to 7.0% by mass, based on the solid content of the liquid printing ink.

[0071] The binder resin (A) is preferably used in an amount of 0.15 to 50% by mass, and most preferably in an amount of 1 to 40% by mass, based on the liquid printing ink.

[0072] (Organic Solvent) The organic solvent used in the organic solvent-based liquid printing ink is not particularly limited, and any known organic solvent can be used. Generally, from the viewpoints of both work hygiene during printing and the harmfulness of materials, ethyl acetate, propyl acetate, isopropanol, normal propanol, etc. are often used.

[0073] (Colorant) The organic solvent-based liquid printing ink contains a colorant, and can be used as a colorant-containing liquid printing ink for use in design printing, etc., for the purpose of imparting cosmetic properties, etc. Examples of colorants include inorganic pigments, organic pigments, and dyes that are used in general inks, paints, recording agents, etc., and pigments are preferred.

[0074] Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, etc. In addition, both non-acid-treated pigments and acid-treated pigments can be used.

[0075] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, and gypsum. Among the inorganic pigments, titanium oxide is particularly preferred. Titanium oxide exhibits a white color and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide is preferably treated with silica and / or alumina. Examples of inorganic pigments other than white include aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, and zircon. Aluminum is in powder or paste form, but is preferably used in paste form from the viewpoints of handleability and safety. Whether leafing or non-leafing is used is appropriately selected from the viewpoints of brightness and density.

[0076] The pigments are preferably contained in an amount sufficient to ensure the concentration and coloring power of the liquid printing ink, i.e., 1 to 60% by mass of the total mass of the liquid printing ink, or 10 to 90% by mass in terms of the weight ratio of solids in the liquid printing ink. These pigments may be used alone or in combination of two or more.

[0077] Organic solvent-based liquid printing inks may further contain waxes, chelating crosslinking agents, extender pigments, leveling agents, antifoaming agents, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, etc., as required.

[0078] (Water-based liquid printing ink) The water-based liquid printing ink is prepared by dispersing a pigment, water alone or a mixture of a water-miscible organic solvent (sometimes referred to as an aqueous medium), a pigment dispersant, an antifoaming agent, etc., in a disperser to obtain a pigment dispersion. The water-based liquid printing ink is obtained by adding an aqueous resin, water or a water-miscible organic solvent, and optionally additives such as a leveling agent, to the obtained pigment dispersion and stirring and mixing. The water-based liquid printing ink is prepared using a disperser such as a bead mill, Eiger mill, sand mill, gamma mill, or attritor, which are commonly used in the production of gravure and flexographic printing inks.

[0079] When the above-mentioned aqueous liquid printing ink is used as a flexographic ink, its viscosity should be 7 to 25 seconds, more preferably 10 to 20 seconds, at 25°C using a Zahn Cup #4 (manufactured by Rigo Co., Ltd.). The surface tension of the resulting flexographic ink at 25°C is preferably 25 to 50 mN / m, more preferably 33 to 43 mN / m. The lower the surface tension of the ink, the better the ink's wetting ability to substrates such as films. However, if the surface tension is below 25 mN / m, the ink tends to spread and connect adjacent dots in halftone dot areas, which can easily cause a stain on the printed surface known as dot bridging. On the other hand, if the surface tension exceeds 50 mN / m, the ink's wetting ability to substrates such as films decreases, which can easily cause cissing.

[0080] On the other hand, when the above-mentioned aqueous liquid printing ink is used as a gravure ink, its viscosity should be 7 to 25 seconds at 25°C using a Zahn Cup #3 (manufactured by Rigo Co., Ltd.), more preferably 10 to 20 seconds. Furthermore, the surface tension of the resulting gravure ink at 25°C is preferably 25 to 50 mN / m, similar to that of flexographic ink, and more preferably 33 to 43 mN / m. The lower the surface tension of the ink, the better the ink's wettability to substrates such as films. However, if the surface tension is below 25 mN / m, the ink tends to spread and connect adjacent dots in halftone dot areas, which can easily cause a stain on the printed surface known as dot bridging. On the other hand, if the surface tension exceeds 50 mN / m, the ink's wettability to substrates such as films decreases, which can easily cause cissing.

[0081] The viscosity of the ink can be adjusted by appropriately selecting the types and amounts of raw materials used, binder resin, pigment, organic solvent, etc. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the pigment in the ink.

[0082] The above-mentioned aqueous liquid printing ink has excellent adhesion to various substrates and can be used for printing on paper, synthetic paper, thermoplastic resin films, plastic products, steel plates, etc. The film thickness of the aqueous liquid printing ink formed by gravure printing or flexographic printing using the above-mentioned aqueous liquid printing ink is, for example, 10 μm or less, preferably 5 μm or less.

[0083] (Aqueous Resin) Examples of aqueous resins used in the aqueous liquid printing ink include water-soluble or water-dispersible urethane resins, polyester resins, acrylic resins, urethane-acrylic resins, styrene-acrylic resins, and styrene-maleic acid resins, and these may be used alone or in combination of two or more. The method for making these resins aqueous-based is not particularly limited, and any conventionally known method may be used. Examples include, but are not limited to, a method of neutralizing the acid groups of these resins with a neutralizing agent, a method of graft polymerizing an ethylenically unsaturated monomer containing an acid group onto these resins and then neutralizing it with a neutralizing agent, and a method of polymerizing an ethylenically unsaturated monomer in an aqueous solvent using an aqueous resin containing acid groups as a polymer emulsifier. The aqueous resin may also have a core-shell structure. When dissolving or dispersing the aqueous resin in an aqueous solvent, a homogenizer or the like may be used as needed.

[0084] Examples of the neutralizing agent include amine compounds such as ammonia, triethylamine, N,N-dimethylethanolamine, and monoethanolamine, non-volatile amine compounds such as triethylenediamine, diethanolamine, triethanolamine, diethylenetriamine, and diazabicyclooctene, metal hydroxides such as lithium hydroxide, potassium hydroxide, and sodium hydroxide, metal chlorides such as potassium chloride and sodium chloride, and metal sulfides such as copper sulfate. From the viewpoint of reducing VOCs, it is preferable to use non-volatile compounds such as non-volatile amine compounds, metal hydroxides, metal chlorides, and metal sulfides.

[0085] When dispersing the aqueous resin in the aqueous solvent described below, an emulsifier may be used in combination. Examples of the emulsifier include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitol tetraoleate, and polyoxyethylene-polyoxypropylene copolymer; anionic emulsifiers such as fatty acid salts such as sodium oleate, alkyl sulfate ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkanesulfonates, and sodium alkyldiphenyl ether sulfonates; and cationic emulsifiers such as alkylamine salts, alkyltrimethylammonium salts, and alkyldimethylbenzylammonium salts.

[0086] The acid value of the aqueous resin is preferably 10 mgKOH / g or more and 300 mgKOH / g or less, and more preferably 10 mgKOH / g or more and 120 mgKOH / g or less. An acid value of 10 mgKOH / g or more can improve the abrasion resistance, water abrasion resistance, and scratch resistance of the laminate when a curing agent is added. The acid value here refers to the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 g of resin. The glass transition temperature of the aqueous resin is not particularly limited, but is, for example, between -30 and 130°C, preferably between -30°C and 55°C. A Tg of -30°C or more maintains the strength of the printed layer and prevents a decrease in the water abrasion resistance of the laminate. A Tg of 55°C or less tends to prevent a decrease in compatibility with other printed layers and maintain the abrasion resistance, water abrasion resistance, and scratch resistance of the laminate. The glass transition temperature (Tg) refers to the so-called calculated glass transition temperature.

[0087] The weight-average molecular weight of the aqueous resin is preferably in the range of 5,000 to 1,500,000. If the weight-average molecular weight is 5,000 or more, the heat resistance of the resin print layer does not decrease, and the laminate tends to be able to maintain its abrasion resistance and water abrasion resistance. If the weight-average molecular weight is 1,500,000 or less, the laminate tends to have both substrate adhesion and scratch resistance.

[0088] The content of the aqueous resin is optional, but for example, it is preferably 5% by mass or more, calculated as solid content, relative to the total mass of the aqueous liquid printing ink, and 70% by mass or less, more preferably in the range of 5 to 50% by mass, from the viewpoint of appropriate ink viscosity and work efficiency during ink production and printing. If the content is 5% by mass or more, the strength of the ink coating is not reduced, and good substrate adhesion, water abrasion resistance, etc. are maintained. Conversely, if the content is 50% by mass or less, a decrease in coloring power can be suppressed, and high viscosity can be avoided, thereby avoiding a decrease in workability.

[0089] (Aqueous Medium) Examples of the aqueous medium include water, or water and a monohydric alcohol solvent such as ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, or 2-methyl-2-propanol; and polyhydric alcohol solvents such as ethylene glycol, 1,3-propanediol, propylene glycol, 1,2-butanediol, 1,4-butanediol, pentylene glycol, 1,2-hexanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, or glycerin.

[0090] glycol ether-based solvents such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether;

[0091] Hydrophilic solvents such as lactam solvents, such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, and ε-caprolactam, and amide solvents, such as formamide, N-methylformamide, N,N-dimethylformamide, and Equamide M-100 and Equamide B-100 manufactured by Idemitsu Co., Ltd., may also be used in combination. These hydrophilic solvents may be used alone or in combination of two or more.

[0092] The combined use of these hydrophilic solvents makes it possible to control the wettability of the substrate and the drying properties of the aqueous liquid printing ink (poor drying of the ink coating). In order to achieve a balance with VOC reduction, the content of the hydrophilic solvent is preferably 10% by mass or less, and more preferably 5% by mass or less, of the total amount of the aqueous liquid printing ink.

[0093] (Colorant) The aqueous liquid printing ink contains a colorant, and can be used as a colorant-containing liquid printing ink for use in design printing, etc., for the purpose of imparting aesthetic appeal, etc. Examples of colorants include inorganic pigments, organic pigments, and dyes used in general inks, paints, and recording agents, etc., with pigments being preferred. As pigments, the same pigments as those used in organic solvent-based liquid printing inks can be used. Furthermore, if the ink does not contain a colorant, it will form a transparent printing layer after printing and can be used as a colorless, transparent ink (in this technical field, it is commonly referred to as an overcoat varnish or OP varnish, as it is solid printed on the outermost layer of a color printing layer and is used to protect the color printing layer; hereinafter in the present invention, it may be referred to as an OP varnish).

[0094] Organic pigments such as yellow, magenta, cyan, and black are preferably blended in at a ratio of 5 to 30% by weight based on the total weight of the aqueous liquid printing ink, and white titanium oxide is preferably blended in at a ratio of 10 to 60% by weight based on the total weight of the aqueous liquid printing ink.

[0095] The average particle size of the pigment is preferably in the range of 1 to 300 nm, more preferably about 50 to 150 nm. The pigment is preferably contained in an amount sufficient to ensure the concentration and coloring power of the aqueous liquid printing ink, i.e., 1 to 60 wt % of the total weight of the ink composition, or 10 to 90 wt % in terms of the weight ratio of solids in the ink composition. These pigments can be used alone or in combination of two or more types.

[0096] (Pigment Dispersing Resin) The aqueous liquid printing ink may contain a pigment dispersing resin for dispersing the pigment. Any water-soluble resin can be used as the pigment dispersing resin as long as it maintains the stability of the ink and has the ability to disperse the pigment. Examples of such pigment dispersing resins include polyvinyl alcohol, polyvinylpyrrolidone (commercially available products include K-30, K-60, and K-90 manufactured by ISP), polyethylene glycol, poly(meth)acrylic acid, (meth)acrylic acid-(meth)acrylic acid alkyl ester copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid alkyl ester copolymer, styrene-(meth)acrylic acid copolymer, maleic acid-(meth)acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, styrene-maleic acid-(meth)acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-(meth)acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, vinylpyrrolidone-(meth)acrylic acid alkyl ester copolymer, vinylpyrrolidone-styrene copolymer, vinylpyrrolidone-vinyl acetate copolymer, and vinyl acetate-croton. water-soluble vinyl copolymers such as vinyl acetate copolymers, vinyl acetate-(meth)acrylic acid copolymers, vinyl acetate-crotonic acid copolymers, polyvinyl sulfonic acid, sodium polyvinyl sulfonate, polystyrene sulfonic acid, sodium polystyrene sulfonate (POLINAS PS-1, POLINAS PS-5, etc., manufactured by Tosoh Corporation), styrene sulfonic acid-maleic acid copolymers, polyitaconic acid, polyhydroxyethyl (meth)acrylate, poly(meth)acrylamide, (meth)acrylamide-(meth)acrylic acid copolymers, polyvinyl methyl ether, methyl vinyl ester, and carboxyvinyl polymers; water-soluble polyurethane resins which are urethane resins obtained by a polyaddition reaction of polyisocyanate and polyol, and in which the entire resin is made water-soluble by the introduction of hydrophilic groups; water-soluble polyester resins which are polyester resins obtained by a polycondensation reaction of polycarboxylic acid and polyol, and in which the entire resin is made water-soluble by the introduction of hydrophilic groups;Examples of such cellulose derivatives include methyl cellulose, ethyl cellulose, propyl cellulose, ethyl methyl cellulose, hydroxyalkyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, alkali metal carboxymethyl cellulose, alkali metal cellulose sulfate, and cellulose graft polymer; and polypeptides such as polyglutamic acid and polyaspartic acid; which may be used alone or in combination of two or more types.

[0097] Among these, from the viewpoint of excellent pigment adsorption ability and dispersion stability, (meth)acrylic acid-(meth)acrylic acid alkyl ester copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid alkyl ester copolymer, styrene-(meth)acrylic acid copolymer, maleic acid-(meth)acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, styrene-maleic acid-(meth)acrylic acid alkyl ester copolymer, and styrene-maleic acid half ester copolymer are preferred. Furthermore, these resins may be synthesized by solution polymerization or bulk polymerization using a radical initiator, or commercially available products may be used.

[0098] Commercially available products include, for example, JONCRYL67, JONCRYL678, JONCRYL586, JONCRYL611, JONCRYL683, JONCRYL690, JONCRYL57J, JONCRYL60J, JONCRYL61J, JONCRYL62J, JONCRYL63D, JONCRYLHPD-96J, JONCRYL501J, and JONCRYLPDX-6102 manufactured by BASF Corporation, and DYSPERBYK180 and DYSPERBYK manufactured by BYK-Chemie. 187, DYSPERBYK190, DYSPERBYK191, DYSPERBYK194, DYSPERBYK2010, DYSPERBYK2015, DYSPERBYK2090, DYSPERBYK2091, DYSPERBYK2095, DYSPERBYK2155, SOLSPERSE41000 manufactured by Lubrizol Corporation, and SMA1000H, SMA1440H, SMA2000H, SMA3000H, and SMA17352H manufactured by Sartomer Corporation.

[0099] The pigment dispersing resin is preferably used in an amount of 10 to 60 parts by mass, calculated as solids, per 100 parts by mass of pigment. If the amount of pigment dispersing resin is less than 10 parts by mass per 100 parts by mass of pigment, the pigment dispersion stability decreases, which may result in poor dispersion stability and storage stability of the aqueous liquid printing ink. On the other hand, if the amount of pigment dispersing resin is more than 60 parts by mass per 100 parts by mass of pigment, the viscosity of the aqueous liquid printing ink increases significantly, which may adversely affect the storage stability of the ink. Furthermore, poor drying of the coating film may occur and the amount of components eluted into water may increase, which may also result in poor coating film properties (adhesion to substrate, water abrasion resistance, and blocking resistance).

[0100] The aqueous liquid printing ink may contain a wax or film-forming emulsion to impart coating resistance. Examples of waxes that can be used include animal and vegetable waxes such as beeswax, lanolin wax, spermaceti, candelilla wax, carnauba wax, rice wax, Japan wax, and jojoba oil; minerals such as montan wax, ozogelite, ceresin, paraffin wax, microcrystalline wax, and petrolatum; synthetic hydrocarbon waxes such as liquid paraffin, natural paraffin, synthetic paraffin, petroleum wax, Fischer-Tropsch wax, polyethylene wax, ethylene-propylene copolymer wax, oxidized polyethylene wax, and oxidized polypropylene wax; modified waxes such as montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives; hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives; and polytetrafluoroethylene wax. Polyethylene wax is preferred from the viewpoint of the balance between static and dynamic friction.

[0101] These waxes may be used alone or in combination of two or more, and the total amount of these waxes added is preferably 0.5 to 5% by mass of the total ink. If the total amount of waxes added is 0.5% by mass or more of the total ink, abrasion resistance, water-resistant abrasion resistance, and scratch resistance can be maintained. If the total amount of waxes added is 5% by mass or less of the total ink, adhesion to the substrate, abrasion resistance, water-resistant abrasion resistance, and scratch resistance can be maintained.

[0102] The film-forming emulsion may be a resin emulsion that forms a film at a glass transition temperature of 10°C or lower. Specific examples include acrylic resin emulsions, water-soluble styrene-acrylic resin emulsions, water-soluble styrene-maleic acid resin emulsions, and water-soluble styrene-acrylic maleic acid resin emulsions. Suitable emulsions are those obtained by copolymerizing a styrene monomer, an alkyl ester of (meth)acrylic acid, or the like, using a water-soluble acrylic resin as a polymer emulsifier.

[0103] The aqueous liquid printing ink may contain a surface conditioner to adjust the leveling ability on the substrate. Examples of surface conditioners include, but are not limited to, Surfynol 104E, 104H, 104A, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, PSA-336, 61, 2502, and Dynol 604 and 607, all manufactured by Nissin Chemical Industry Co., Ltd., and BYK-381, 3441, 302, 307, 325, 331, 333, 342, 345, 346, 347, 348, 349, 378, and 3455, all manufactured by BYK-Chemie. Among these, acetylene-based surfactants and / or alcohol alkoxylate-based surfactants are preferred. Commercially available products include alkylene oxide-unmodified acetylene glycol surfactants such as Surfynol 61, 82, and 104 (all manufactured by Evonik), and alkylene oxide-modified acetylene glycol surfactants such as Surfynol 420, 440, 465, 485, TG, and 2502, Dynol 604 and 607 (all manufactured by Evonik), Surfynol SE, MD-20, Olfine E1004, E1010, PD-004, EXP4300, PD-501, PD-502, and SPC (all manufactured by Nissin Chemical Industry Co., Ltd.), and Acetylenol EH, E40, E60, E81, E100, and E200 (all manufactured by Kawaken Fine Chemicals Co., Ltd.). Of these, alkylene oxide-modified acetylene glycol surfactants are preferred. Specific examples of alcohol alkoxylate surfactants include alcohol ethoxylate and alcohol polyethoxylate, and a commercially available product thereof is DYNWET 800 (manufactured by BYK Japan KK). Furthermore, if necessary, other acrylic polymer surfactants (e.g., Polyflow WS-314 manufactured by Kyoeisha Chemical Co., Ltd.) and modified silicone surfactants (e.g., Polyflow KL-401 manufactured by Kyoeisha Chemical Co., Ltd.) may also be used.

[0104] The total amount of surface conditioners added is preferably 0.1 to 1% by mass of the total ink. These surface conditioners may be used alone or in combination of two or more. When the total amount of surface conditioners added is 0.1% by mass or more of the total ink, the wetting ability with the substrate is improved and adhesion to the substrate can be maintained. When the total amount of surface conditioners added is 1% by mass or less of the total ink, there is no decrease in abrasion resistance, water abrasion resistance, and scratch resistance.

[0105] Various additives can be added to aqueous liquid printing inks, such as extender pigments such as calcium carbonate, kaolin, barium sulfate, aluminum hydroxide, clay, and talc to improve drying properties, inorganic fine particles and adhesive resins (acrylic resins, vinyl acetate resins) to impart slip resistance, antifoaming agents to impart defoaming properties, and basic compounds such as caustic soda to impart resolubility.

[0106] (Curing Agent) In the aqueous liquid printing ink, a curing agent capable of reacting with an acid may be used in combination. The curing agent capable of reacting with an acid is not particularly limited, and any known curing agent that can be used in an aqueous medium may be used. Examples thereof include epoxy-based curing agents, carbodiimide-based curing agents, and oxazoline-based curing agents.

[0107] The epoxy curing agent is not particularly limited as long as it is a compound having at least one epoxy group, and examples of the epoxy curing agent include epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether.

[0108] The carbodiimide curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (—N═C═N—). As the carbodiimide curing agent, a polycarbodiimide compound having at least two carbodiimide groups is preferred.

[0109] The oxazoline curing agent is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the oxazoline curing agent include the EPOCROS series manufactured by Nippon Shokubai Co., Ltd. Examples of the epoxy compound include diglycidyl ether of bisphenol A and its oligomer, diglycidyl ether of hydrogenated bisphenol A and its oligomer, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-oxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ester, and the like. diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-diglycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, triglycidyl ethers of glycerol alkylene oxide adducts, and the like.

[0110] The amount of curing agent added is preferably 0.1 to 10.0 mass % of the total amount of ink, calculated as solid content, and more preferably in the range of 0.5 to 9.0 mass %. If the amount added is 0.1 mass % or more, the effect as a curing agent can be obtained, while if it is 10.0 mass % or less, the adhesion to the substrate, abrasion resistance, and water abrasion resistance tend to be maintained.

[0111] Water-based liquid printing inks may further contain, as necessary, chelating crosslinking agents, antifoaming agents, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, etc. Among these, they often contain fatty acid amides such as oleic acid amide, stearic acid amide, and erucic acid amide to impart abrasion resistance, slipperiness, etc., silicone-based or non-silicone antifoaming agents to suppress foaming during printing, and various pigment dispersants to improve pigment wetting.

[0112] (Biomass Liquid Printing Ink) In terms of liquid printing ink, it is preferable to use liquid printing ink made from plant-derived raw materials, taking into consideration the establishment of a recycling-based society that should continue to develop (sustainability). Examples of plant-derived raw materials include cellulose resins such as cellulose acetate propionate resin and nitrocellulose; polyamide resins using dimer acids or polymerized fatty acids derived from natural oils such as soybean oil, palm oil, and rice bran oil; biomass polyurethanes synthesized from plant-derived raw materials such as polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid; polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, and isosorbide; and polyisocyanates such as 1,5-pentamethylene diisocyanate and dimer diisocyanate; and rosin resins.

[0113] Commercially available products can also be used as biomass liquid printing inks, such as those listed by the Japan Organics Recycling Association.

[0114] (Formation of Printed Layer) In the present invention, a printed matter is obtained by printing a liquid printing ink onto a substrate to provide a printed layer. Typically, the ink is applied to the substrate using a gravure or flexographic printing method, and then dried and fixed in an oven to obtain a printed layer. The drying temperature is usually about 40 to 60°C.

[0115] Flexographic printing is a type of relief printing that mainly uses a resin plate as the printing plate (relief plate) and a fine-mesh engraved roll called an anilox roll to supply ink to the plate. The anilox roll receives ink from a chamber-type doctor and applies it to the plate, and has the advantage of being able to transfer ink evenly to the plate.

[0116] Specifically, ink is applied to the surface of an anilox roll, which has partition walls and numerous openings surrounded by the partition walls, a doctor is pressed against the surface of the anilox roll to scrape off the ink present on the top surfaces of the partition walls of the anilox roll, and the ink fills the recesses that are the openings. Next, a flexographic plate is pressed against the anilox roll to transfer the ink present in the recesses of the anilox roll to the raised areas (pattern areas) of the printing plate, and the plate is then brought into contact with a substrate to transfer the ink present in the pattern areas of the plate to the substrate on which a primer layer has been formed, thereby obtaining a printed product.

[0117] Rotary printing methods may also be combined. For example, a method for producing a rotary printed product involves rotary printing using liquid printing ink on the surface of a wound film on which a primer layer has been formed. After printing, processes such as lamination, slitting (cutting out unnecessary width portions), and bag making (cutting out and heat sealing to make bags) can be performed. Rotary printing of liquid printing ink onto a wound film enables high-speed printing and is highly productive. Rotary printing includes gravure rotary printing and flexographic rotary printing, and either method is acceptable, but flexographic rotary printing will be described in detail here. In this specification, rotary printing refers to gravure rotary printing and flexographic rotary printing.

[0118] In flexographic rotary printing, ink is supplied from a container that stores liquid printing ink directly or via an ink supply pump or the like to an anilox roller having an uneven surface. The ink supplied to the anilox roller is transferred to the plate surface by contact with the raised portions of the plate surface, and is further transferred to the base film by contact between the plate surface and the base film, thereby forming a pattern and / or characters.

[0119] When using aqueous flexographic printing ink, the ink drying speed is slightly inferior to that of solvent-based flexographic printing ink, so it is preferable to make the ink film thickness as thin as possible. From this perspective, it is preferable to supply as little ink as possible to the anilox roller. On the other hand, as the film thickness becomes thinner, the print density tends to decrease, so the pigment concentration of the aqueous flexographic printing ink used can be controlled appropriately. Specifically, an appropriate print density can be obtained by increasing the pigment concentration of the aqueous flexographic printing ink by 1 to 5% by weight compared to the concentration of the solvent-based flexographic printing ink.

[0120] The term "wound film" refers to a roll of thermoplastic resin film aligned to a specified width, and is a film for rotary printing, unlike sheets of paper that are pre-cut one by one. The width of the film is appropriately selected based on the plate width of the rotary printing press used and the width of the image (design) portion of the gravure plate. In the present invention, a wound film on which a removable primer layer has been formed in advance can be used. When multiple colors of rotary printing inks are used to overlay colors, the order of printing them is not particularly limited.

[0121] When performing surface printing, it is common to print white ink first, and then colored inks, if necessary. When multiple colored inks are used, they can be printed in the order of, for example, yellow, magenta, cyan, and black, but this is not particularly limited. In the case of a surface printing configuration, abrasion resistance, water resistance, etc. can be improved by applying an overcoat agent to the printed surface of the rotary printed matter as needed. When the substrate is white, i.e., for example, a paper substrate or a thermoplastic resin film kneaded with a white pigment, printing with only colored inks is also possible as needed.

[0122] In reverse printing, it is common to first print color inks on a rolled film, followed by white ink. When multiple color inks are used, they can be printed in the following order, for example, black, cyan, magenta, and yellow, but this is not particularly limited. Large-format printing machines can also use special colors in addition to the basic colors. That is, large-format printing machines have multiple printing units corresponding to 5 to 10 colors, each equipped with one ink color, allowing for 5 to 10 colors to be printed simultaneously. Printed materials obtained by reverse printing can be used as is, or an anchor coating agent and adhesive can be applied to the printed surface of a rotary printed material obtained by the above method, and after drying, the printed material can be laminated with a film or the like to form a laminate.

[0123] The printed matter of the present invention has excellent ink releasability and is therefore suitable for a form in which the printed layer is the outermost layer. In the case of the front-printed printed matter or the back-printed printed matter, the effects of the present invention can be maximized in a printed matter in which a liquid printing ink printed layer is provided on the surface that will be the outermost layer during distribution, or in a printed matter in which the printed layer is provided on the inner side that comes into direct contact with the product.

[0124] (Gas barrier resin layer) (Gas barrier resin layer A) An example of the gas barrier resin layer is a gas barrier resin layer A that can be obtained by applying a gas barrier coating agent containing a vinyl alcohol polymer and an aqueous solvent by a known coating method to form a coating film. Specific examples of the vinyl alcohol polymer include polyvinyl alcohol, ethylene vinyl alcohol, polyvinyl butyral, etc. The vinyl alcohol polymer may have a reactive functional group other than a hydroxyl group, such as an acetoacetyl group, a carboxyl group, an anionic carboxyl group, a sulfonic acid group, or an anionic sulfonic acid group. These may be used alone or in combination of two or more.

[0125] The vinyl alcohol polymer preferably has a saponification degree of 90% or more, more preferably 95% or more, because it has excellent gas barrier properties. It may also be 100%. The saponification degree can be measured by FTIR using, for example, a Nicolet 5700 FTIR spectrometer controlled by OMNIC software.

[0126]

[0113] The gas barrier coating agent constituting the gas barrier resin layer A may further contain additives such as a layered inorganic compound, a crosslinking agent capable of reacting with a functional group possessed by the vinyl alcohol polymer, an adhesion improver, an inorganic filler, an antifoaming agent, a stabilizer (antioxidant, heat stabilizer, ultraviolet absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, and a leveling agent.

[0127] The amount of the gas barrier coating agent that constitutes the gas barrier resin layer A is adjusted appropriately depending on the desired level of gas barrier properties. For example, ２ ~5.0g / m ２ , more preferably 0.3 g / m ２ ~2.0 g / m ２ is.

[0128] The gas barrier coating agent that constitutes the gas barrier resin layer A may be a commercially available product, and examples thereof include EXEVIA (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., the SunBar (registered trademark) series manufactured by Sun Chemical Co., Ltd., the Takelac WPB (registered trademark) series manufactured by Mitsui Chemicals, Inc., and LG-OX manufactured by Tokyo Ink Co., Ltd.

[0129] (Gas Barrier Resin Layer B) The gas barrier resin layer may be, for example, a water-soluble polymer having a hydroxyl group, such as a vinyl alcohol polymer, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, or sodium alginate, and a Si(OR １ ) ４ , or R ２ Si(OR ３ ) ３ (However, OR １ and OR ３ represents a hydrolyzable group, R ２represents an organic functional group), or one or more hydrolysates of the silicon compounds, and an aqueous solvent, and then applying the gas barrier coating agent by a known coating method to form a coating film.

[0130] The water-soluble polymer used in the present invention is preferably a vinyl alcohol polymer, since it can impart good gas barrier properties. Specific examples of suitable vinyl alcohol polymers include polyvinyl alcohol, ethylene vinyl alcohol, polyvinyl butyral, etc. One type may be used alone, or two or more types may be used in combination. From the viewpoint of the balance between gas barrier properties and adhesion, it is more preferable to use either polyvinyl alcohol or ethylene vinyl alcohol, or both.

[0131] The Si(OR １ ) ４ , or R ２ Si(OR ３ ) ３ (However, OR １ and OR ３ represents a hydrolyzable group, R ２ represents an organic functional group), or a hydrolyzate of the silicon compound, for example, tetraethyl silicate (Si(OC ２ H ５ ) ４ ) (hereinafter sometimes referred to as TEOS), tetraalkoxysilanes such as tetramethyl silicate; trialkoxysilanes such as trimethoxymethylsilane, triethoxymethylsilane, trimethoxyvinylsilane; dialkoxysilanes such as dimethoxydimethylsilane, diethoxydimethylsilane; monoalkoxysilanes such as methoxytrimethylsilane, ethoxytrimethylsilane, or hydrolysates or partial hydrolysates thereof.

[0132] TEOS is preferred because it is relatively stable in an aqueous solvent after hydrolysis. ２ Si(OR ３ ) ３ Contains R ２is preferably a vinyl group, an epoxy group, an acryloyl group, a methacryloxy group, a ureido group, or an isocyanate group.

[0133] When the water-soluble polymer is a vinyl alcohol polymer, the ratio of the mass of the vinyl alcohol polymer to the mass of the total solid content of the mixed solution is preferably 20% by mass or more and 50% by mass or less, and more preferably 25% by mass or more and 40% by mass or less. By containing 20% ​​by mass or more of PVA, the flexibility of the coating film is maintained. Therefore, the coating film can be easily formed. Furthermore, by containing 50% by mass or less of the vinyl alcohol polymer, sufficient barrier properties can be obtained.

[0134] The gas barrier resin layer may contain other components such as other water-soluble polymers (e.g., sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.), fragrances, rust inhibitors, colorants, bulking agents, antifoaming agents, ultraviolet absorbers, fluorescent brighteners, liquid paraffins, bitter components (e.g., denatonium benzoate, etc.), etc.

[0135] The thickness of the gas barrier resin layer B is preferably selected from the range of, for example, 0.05 μm or more and 30 μm or less.

[0136] (Gas barrier resin layer C) Another example of the gas barrier resin layer is a gas barrier resin layer C that can be obtained by applying, by a known coating method, a gas barrier coating agent that includes a polyester polyol, which is a reaction product of a polyol component and an acid component that essentially contains an ortho-oriented polycarboxylic acid or a meta-oriented polycarboxylic acid, an isocyanate compound, and an organic solvent to form a coating film.

[0137] (Acid Component Ortho-Oriented Polycarboxylic Acid or Meta-Oriented Polycarboxylic Acid) Examples of ortho-oriented polycarboxylic acids used in the synthesis of polyester polyols 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 a substituent on any carbon atom of the aromatic ring. Furthermore, examples of meta-oriented polycarboxylic acids used in the synthesis of polyester polyols include isophthalic acid and 1,3-naphthalenedicarboxylic acid. These compounds may have a substituent on any carbon atom of the aromatic ring.

[0138] In addition, the polycarboxylic acid may contain a known polycarboxylic acid other than the ortho- orientated polycarboxylic acid or meta-orientated polycarboxylic acid. When the polycarboxylic acid contains a polycarboxylic acid other than the ortho- orientated polycarboxylic acid or meta-orientated polycarboxylic acid, the proportion of the ortho- or meta-orientated polycarboxylic acid in the total amount of polycarboxylic acids is preferably 40 to 100 mass%.

[0139] (Polyol Component) The polyol component used in the synthesis of polyester polyol preferably contains a dihydric alcohol such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, or cyclohexane dimethanol, or a trihydric alcohol such as glycerol, trimethylolethane, or trimethylolpropane. Among these, ethylene glycol or glycerol is more preferable. Glycerol is particularly preferable. The polyol component of polyol (A) preferably contains 10 to 100% by mass of glycerol. Other known polyhydric alcohols may also be used in combination. The polyester polyol may be a single type, or a combination of multiple polyols. The polyester polyol may also be a polyester polyurethane polyol that has been urethane-extended by reaction with a diisocyanate compound.

[0140] The hydroxyl value of the polyester polyol is preferably 20 mgKOH / g or more and 250 mgKOH / g or less. When the polyester polyol has an acid group, the acid value is preferably 200 mgKOH / g or less.

[0141] (Isocyanate Compounds) The isocyanate compound used in the present invention can be a conventionally known one without any particular limitation, and examples thereof include adducts obtained by reacting tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, or trimers of these isocyanate compounds, and an excess amount of these isocyanate compounds with low-molecular-weight active hydrogen compounds such as ethylene glycol, propylene glycol, meta-xylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, and meta-xylylenediamine, and alkylene oxide adducts thereof, various polyester resins, polyether polyols, and polymeric active hydrogen compounds such as polyamides. Alternatively, polyester polyisocyanates obtained by reacting polyester polyols with diisocyanate compounds in an isocyanate excess ratio relative to hydroxyl groups may be used. Blocked isocyanates may also be used. These may be used alone or in combination of two or more.

[0142] The isocyanate compound preferably has an aromatic ring or an aliphatic ring, which is expected to improve the gas barrier properties and blocking resistance of the coating film.

[0143] A known epoxy compound may be used in combination with the polyisocyanate compound. When an epoxy compound is used, a known general-purpose epoxy curing accelerator may be added as needed to accelerate curing, provided that the object of the present invention is not impaired.

[0144] It is also preferable to use a compound having an active hydrogen group in combination with the polyisocyanate compound. Examples of the active hydrogen group in the compound having active hydrogen include a hydroxyl group, an amino group, an imino group, a carboxylic acid, a urea group, and an SH group. Of these, a hydroxyl group, an amino group, or an SH group is preferred. Of these, a compound (C) having a hydroxyl group as the active hydrogen group is preferred, and isosorbide, tris(2-hydroxyethyl) isocyanurate, trimethylolpropane, dipentaerythritol, and 1,4-cyclohexanedimethanol are preferred.

[0145] The amount of the compound having an active hydrogen group is preferably 0.5% by mass or more and 20% by mass or less based on the solid content of the gas barrier layer. Within this range, winding blocking during coating is prevented, and good substrate adhesion and improved gas barrier properties of the coating film are expected. A blending amount of 1% by mass or more and 15% by mass or less is more preferred, and a blending amount of 2% by mass or more and 8% by mass or less is most preferred.

[0146] (Other Components) The gas barrier resin layer C may also contain other components such as known plate-like inorganic compounds, low-molecular-weight organic compounds that react with oxygen, such as acid anhydrides, hindered phenols, vitamin C, vitamin E, organic phosphorus compounds, gallic acid, and pyrogallol, transition metal compounds of cobalt, manganese, nickel, iron, and copper, inorganic fillers such as silica, alumina, aluminum flakes, and glass flakes, and, when an inorganic material is used, dispersants, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, and the like), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, leveling agents, and slip improvers.

[0147] (Gas barrier resin layer D) Another example of the gas barrier resin layer is a gas barrier resin layer D that can be obtained by applying a gas barrier coating agent containing a dehydration condensable heteroatom compound, a polymer having a carboxyl group, and an organic solvent by a known coating method to form a coating film.

[0148] (Heteroatom Compound Having Dehydration Condensation Properties) The heteroatom compound having dehydration condensation properties used in the present invention is a compound that undergoes dehydration condensation when contacted with a compound having a hydroxyl group, and is a compound that has a heteroatom in its structure. Examples of these heteroatom compounds having dehydration condensation properties include phosphoric acid, sulfuric acid, and nitric acid. These may be used alone or in combination. The amount of the heteroatom compound having dehydration condensation properties added is preferably 10 parts by mass or less in the gas barrier resin layer.

[0149] (Polymer having a carboxyl group) Examples of the polymer having a carboxyl group used in the present invention include a polymer of a polymerizable unsaturated monomer having a carboxyl group and a copolymer of a polymerizable unsaturated monomer having a carboxyl group and a general-purpose polymerizable unsaturated monomer. Examples of the polymerizable unsaturated monomer having a carboxyl group include unsaturated carboxylic acids such as (meth)acrylic acid, 2-carboxyethyl (meth)acrylate, crotonic acid, itaconic acid, maleic acid, and fumaric acid; monoesters (half esters) of various unsaturated dicarboxylic acids such as monomethyl itaconate, mono-n-butyl itaconate, monomethyl maleate, mono-n-butyl maleate, monomethyl fumarate, and mono-n-butyl fumarate with saturated monohydric alcohols; monovinyl esters of various saturated dicarboxylic acids such as monovinyl adipate and monovinyl succinate; addition reaction products of various saturated polycarboxylic acid anhydrides such as succinic anhydride, glutaric anhydride, phthalic anhydride, and trimellitic anhydride with various hydroxyl group-containing vinyl monomers; and various monomers obtainable by addition reaction of the above-mentioned various carboxyl group-containing monomers with lactones.

[0150] The acid value of the polymer having a carboxyl group is preferably 50 to 800 mgKOH / g, as this improves barrier performance. The polymer having a carboxyl group used in the present invention is not particularly limited in molecular weight, but a weight average molecular weight of 300 to 1,000,000 is preferred from the viewpoint of improving coating film formability. A weight average molecular weight of 500 to 500,000 is particularly preferred.

[0151] Furthermore, it is also preferable that the gas barrier resin layer D has a resin layer containing a polyvalent metal compound adjacent thereto. Here, "adjacent" means that there is at least a portion where the resin layers are in direct contact with each other.

[0152] Examples of polyvalent metal compounds contained in the resin layer include zinc compounds, magnesium compounds, calcium compounds, manganese compounds, iron compounds, cobalt compounds, nickel compounds, and copper compounds, with zinc compounds, magnesium compounds, and calcium compounds being particularly preferred. These metal compounds may be used alone or in combination of two or more, with zinc oxide, magnesium oxide, and calcium oxide being particularly preferred. These polyvalent metal compounds are preferably contained in the resin layer containing the polyvalent metal compound in an amount of 40 to 90 parts by mass.

[0153] In addition to the polyvalent metal compound, the resin layer containing the polyvalent metal compound preferably contains an ethyl cellulose resin, a polyether polyurethane polyol resin, a polyester polyol resin, or a polyurethane polyol resin in an amount of 10 to 60 parts by mass in order to stably coat the polyvalent metal compound.

[0154] Furthermore, it is also preferable that the gas barrier resin layer D has an adjacent layer containing aluminum oxide, silicon oxide, silicon nitride, or the like. These adjacent layers are layers formed by processes such as vapor deposition, sputtering, CVD, or the like using a compound selected from the group consisting of aluminum oxide, silicon oxide, and silicon nitride. These layers may be formed on substrate films such as polyethylene terephthalate (PET) resin films, polypropylene (PP) resin films, polybutylene terephthalate (PBT) resin films, nylon (NY) resin films, and biomass films. These substrate films may be films manufactured by various known processes, such as biaxially stretched films, stretched films, and non-stretched films, or films that have been subjected to various surface treatments as necessary.

[0155] The gas barrier resin layer D has a coating amount after drying of 0.01 to 100 g / m 2 is preferred, and 0.1 to 50 g / m 2 More preferably, 0.5 to 3 g / m 2 is particularly preferred.

[0156] (Heat-resistant resin layer) The heat-resistant resin layer is a coating film layer of a coating agent having heat resistance (hereinafter, may be simply referred to as a heat-resistant coating agent). As the heat-resistant coating agent, a commercially available product can be used. Examples of commercially available products include SUNSYSFS241 manufactured by Sun Chemical Company, DH-004 / DH-HARDENERP-60 manufactured by DIC Corporation, and ThermaGloss 463 manufactured by Michelman.

[0157] Also preferred are heat-resistant coating agents containing compounds having a cellulose skeleton, a benzene ring skeleton, an isocyanuric ring skeleton, or an alicyclic skeleton, whose homopolymer glass transition temperature (hereinafter sometimes referred to as Tg) is 100°C or higher. Specific examples include cellulose derivatives such as nitrocellulose, cellulose acetate, cellulose propionate, and cellulose butyrate; polyester resins having a benzene ring such as phthalic acid, naphthalenedicarboxylic acid, and an ethylene oxide (hereinafter sometimes referred to as EO) adduct of bisphenol A, and / or an alicyclic skeleton such as cyclopentanediol and dimethyloltricyclodecane; aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate and norbornene diisocyanate; and / or urethane resins obtained by combining isocyanuric triisocyanate with a polyol and / or tris(2-hydroxyethyl)isocyanurate. Polyisocyanates using the above-mentioned isocyanates may also be used as the curing agent. In addition, 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 are also preferably used. Furthermore, in consideration of adhesion to olefin films, resins with low Tg may be mixed in and used. The total amount of the cellulose skeleton, benzene ring skeleton, isocyanuric ring skeleton, and alicyclic skeleton of the aforementioned compounds is preferably 20 to 90% by mass, and more preferably 30 to 80% by mass, of the solid content of the heat-resistant coating layer.

[0158] The heat-resistant coating agent may be colored. The colorant is not particularly limited, and examples thereof include inorganic pigments, organic pigments, and dyes used in general inks, paints, and recording agents, such as those used in the printing layer described below. Among these, pigments are preferred. Among inorganic pigments, titanium oxide is particularly preferred. Titanium oxide is white and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide is preferably treated with silica and / or alumina. Aluminum is in powder or paste form, but it is preferably used in paste form from the viewpoints of handleability and safety. Whether leafing or non-leafing aluminum is used is appropriately selected from the viewpoints of brightness and density.

[0159] Furthermore, the heat-resistant coating agent preferably uses inorganic fine particles such as alumina, magnesia, titania, zirconia, and silica (quartz, fumed silica, precipitated silica, silicic anhydride, fused silica, crystalline silica, ultrafine amorphous silica, etc.) as aggregates, as these have excellent heat resistance. Alternatively, boron nitride, aluminum nitride, alumina oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, etc. are preferred due to their excellent thermal conductivity. The inorganic fine particles may be used alone or in combination of two or more types. The shape of the silica fine particles is not particularly limited, and spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous silica particles may be used. For example, commercially available hollow silica fine particles such as "SiliNax" manufactured by Nittetsu Mining Co., Ltd. may be used.

[0160] The primary particle diameter of the inorganic fine particles is preferably in the range of 5 to 200 nm. If the diameter is 5 nm or more, the inorganic fine particles are well dispersed in the dispersion, and if the diameter is 200 nm or less, the strength of the cured product is good. A diameter of 10 nm to 100 nm is more preferable. The inorganic fine particles can be blended in a ratio of 5 to 90 wt % based on the total solid content of the heat-resistant coating agent and the inorganic fine particles, and the blending amount can be changed as needed depending on the purpose. In particular, a ratio of 20 mass % or more is preferable.

[0161] Waxes, silicone additives, and organic beads can be added to the heat-resistant coating agent to prevent scratches on the coated film, prevent blocking during laminate formation, and improve processability during bag manufacturing after the laminate is produced. 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 modified silicones, and organic beads made of acrylic, nylon, urethane, or epoxy can be added.

[0162] The solvent used in the heat-resistant coating agent is not particularly limited, and may be used alone or in combination of two or more. In order to carry out coating more effectively, a defoaming agent and a leveling agent may also be used.

[0163] The amount of the heat-resistant resin layer to be applied is appropriately selected depending on the application, but the amount of the applied heat-resistant resin layer after drying is preferably 0.01 to 100 g / m ２ is preferred, and 0.1 to 50 g / m ２ More preferably, 0.5 to 3 g / m ２ is particularly preferred.

[0164] <Recycling Method> The recycling method in the present invention is a method in which a printed material having a plastic substrate, a detachment primer layer, and a printed layer laminated in this order is immersed in an alkaline aqueous solution that is a detachment treatment liquid, and other layers (particularly the printed layer) provided on the plastic substrate are detached from the plastic substrate. Note that detachment refers to the separation of the plastic substrate from the other layers as a result of the detachment primer layer swelling or slightly dissolving and peeling off in the detachment treatment liquid. The detached plastic substrate can be used as recycled plastic.

[0165] The detachment step includes immersing the printed material in an alkaline aqueous solution while stirring or ultrasonically vibrating it at a liquid temperature of 40 to 90°C. Heating and stirring and ultrasonic vibration may be performed simultaneously. The immersion time is 60 minutes or less, more preferably 30 minutes or less, more preferably 20 minutes or less, and even more preferably 15 minutes or less. The temperature of the alkaline aqueous solution is preferably 40°C or higher, more preferably 50°C or higher. The liquid temperature is preferably 100°C or lower, more preferably 90°C or lower. It is also more preferable to perform stirring and ultrasonic vibration simultaneously. The detachment primer layer of the present invention is resistant to alkaline aqueous solutions at low temperatures (below 40°C), and even if the printed material unintentionally comes into contact with an alkaline aqueous solution such as a cleaning solution in daily life, the coating film consisting of the printed layer will not detach from the printed material. Therefore, a preferred recycling method involves immersing the printed material in an alkaline aqueous solution at 40°C or higher to detach the printed layer from the plastic substrate.

[0166] The alkaline aqueous solution used in the detachment step is not limited, but is preferably a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, a sodium bicarbonate aqueous solution, a potassium bicarbonate aqueous solution, a sodium dihydrogen carbonate aqueous solution, or a potassium dihydrogen carbonate aqueous solution. The sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, a sodium bicarbonate aqueous solution, a potassium bicarbonate aqueous solution, a sodium dihydrogen carbonate aqueous solution, or a potassium dihydrogen carbonate aqueous solution is preferably an aqueous solution having a concentration of 0.001% by mass to 10% by mass, more preferably 0.005% by mass to 5% by mass, more preferably 0.01% by mass to 3% by mass, more preferably 0.05% by mass to 1.5% by mass, and even more preferably 0.1% by mass to 0.5% by mass. The pH of the alkaline aqueous solution is preferably 9.0 or higher, more preferably 10.0 or higher. The detachment primer layer of the present invention is easily detached by heating even in a low-concentration, low-pH alkaline aqueous solution, making it suitable for recycling.

[0167] The alkaline aqueous solution may contain a water-soluble organic solvent, such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol dibutyl ether, diethylene glycol monomethyl ether (methyl carbitol), diethylene glycol dimethyl ether, diethylene glycol monoethyl ether (carbitol), diethylene glycol diethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol dibutyl ether, diethylene glycol dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ... Examples include glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methylene dimethyl ether (methylal), propylene glycol monobutyl ether, tetrahydrofuran, acetone, diacetone alcohol, acetonylacetone, acetylacetone, ethylene glycol monomethyl ether acetate (methyl cellosolve acetate), diethylene glycol monomethyl ether acetate (methyl carbitol acetate), diethylene glycol monoethyl ether acetate (carbitol acetate), ethyl hydroxyisobutyrate, and ethyl lactate, and these can be used alone or in combination of two or more.

[0168] The content of the water-soluble organic solvent in the alkaline aqueous solution is preferably 0.01% by mass to 20% by mass, and more preferably 0.1% by mass to 10% by mass.

[0169] The aqueous alkaline solution may contain a water-insoluble organic solvent. Specific examples of the water-insoluble organic solvent include alcohol solvents such as n-butanol, 2-butanol, isobutanol, and octanol, aliphatic hydrocarbon solvents such as hexane, heptane, and normal paraffin, aromatic hydrocarbon solvents such as benzene, toluene, xylene, and alkylbenzene, halogenated hydrocarbon solvents such as methylene chloride, 1-chlorobutane, 2-chlorobutane, 3-chlorobutane, and carbon tetrachloride, ester solvents such as methyl acetate, ethyl acetate, and butyl acetate, ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone, and ether solvents such as ethyl ether and butyl ether. These may be used alone or in combination of two or more.

[0170] The alkaline aqueous solution preferably contains a surfactant, such as various anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, with cationic surfactants being preferred.

[0171] The cationic surfactant is preferably a cationic surfactant having a quaternary ammonium skeleton, and more preferably contains, for example, a cationic surfactant having a quaternary ammonium skeleton containing at least one compound represented by general formula (3a).

[0172] R1-N+(RR)-R4(3a) (In general formula (3a), R1 represents a linear or branched alkyl group, or a linear or branched alkenyl group, and —CH2- in the alkyl or alkenyl group may be substituted with —C(═O)—, —NH—, or —C(═O)—NH—; R2 and R3 represent a hydrogen atom, a linear or branched alkyl group, or a linear or branched alkenyl group; R4 represents a hydrogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, or a phenyl group, and the terminal —CH3 in the alkyl or alkenyl group may be substituted with a carboxy group or a phenyl group.) In general formula (3a), R1 is preferably a long-chain alkyl group or alkenyl group in order to further enhance ink releasability, specifically preferably an alkyl group or alkenyl group having 8 to 30 carbon atoms, preferably an alkyl group having 10 to 25 carbon atoms, or preferably an alkyl group or alkenyl group having 12 to 22 carbon atoms. The alkyl group or alkenyl group may be linear or branched, but is preferably linear, and more preferably a linear alkyl group.

[0173] In R1, at least one -CH2- group in the alkyl group or alkenyl group may be substituted with -C(=O)-, -NH-, or -C(=O)-NH-. Among these, it is preferable that at least one -CH2- group in the alkyl group or alkenyl group is substituted with -C(=O)-NH- or -NH-C(=O), it is preferable that one -CH2- group in the alkyl group is substituted with -C(=O)-NH- or -NH-C(=O), and it is more preferable that R1 has an amidopropyl skeleton.

[0174] R2 and R3 each preferably represent a linear or branched alkyl group or a linear or branched alkenyl group, more preferably a linear or branched alkyl group, particularly preferably a linear alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0175] R4 preferably represents a linear or branched alkyl group, a linear or branched alkenyl group, or a phenyl group, and more preferably represents a linear or branched alkyl group. Furthermore, the terminal —CH3 in the alkyl or alkenyl group is preferably substituted with a carboxy group or a phenyl group.

[0176] R4 preferably has 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, even more preferably 1 to 3 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0177] When R4 represents a methyl group, it is preferred that R2 and R3 also represent methyl groups, and general formula (3a) represents an alkyltrimethylammonium skeleton.

[0178] Furthermore, when R4 represents an ethyl group, the terminal —CH3 in the ethyl group is preferably substituted with a carboxy group or a phenyl group, i.e., R4 preferably represents —CH2—(C(═O))OH or a benzyl group.

[0179] The compound represented by formula (3a) is preferably a cationic surfactant having a quaternary ammonium skeleton represented by formula (3a-1).

[0180] CnH2n+1N+(CH3)2R4(3a-1) (In general formula (3a-1), n ​​represents the average number of moles added, and R4 has the same meaning as R4 in general formula (3a).) In general formula (3a-1), the number of carbon atoms represented by n is preferably 8 or more. The greater the number of carbon atoms, e.g., 8 or more, the better the ink releasability, and this is preferred. Specific examples of groups having different carbon atoms include an octyl group having 8 carbon atoms, a nonyl group having 9 carbon atoms, a decyl group having 10 carbon atoms, an undecyl group having 11 carbon atoms, a lauryl group having 12 carbon atoms, a tridecyl group having 13 carbon atoms, a myristyl group having 14 carbon atoms, a pentadecyl group having 15 carbon atoms, a cetyl group having 16 carbon atoms, and an oleyl group and a stearyl group, each having 18 carbon atoms.

[0181] Preferred groups for R4 are the same as those in formula (3a).

[0182] These cationic surfactants with a quaternary ammonium skeleton are preferably of the quaternary ammonium skeleton salt type that forms a salt with a halogen, and preferably form a salt with Cl-, more preferably form a salt with Br-, and even more preferably form a salt with I-. Quaternary ammonium skeleton salts that form a salt with a halogen promote hydrolysis of the ink film due to the nucleophilic action of the halogen, and are therefore thought to improve the releasability of the ink.

[0183] Among these, alkyltrimethylammonium chloride type, dialkyldimethylammonium chloride type, and alkylbenzalkonium chloride type compounds are preferred.

[0184] Specific products corresponding to the general formula (3a) or (3a-1) include, manufactured by NOF Corporation, Nissan Cation MA, Nissan Cation SA, Nissan Cation BB, Nissan Cation FB, Nissan Cation PB-300, Nissan Cation ABT2-500, Nissan Cation AB, Nissan Cation AB-600, Nissan Cation VB-M Flake, Nissan Cation VB-F, Nissan Cation 2-DB-500E, Examples of such a surfactant include Nissan Cation 2-DB-800E, Nissan Cation 2ABT, Nissan Cation 2-OLR, Nissan Cation F2-50R, and Nissan Cation M2-100R. Examples of such a surfactant include Catiogen TML, Catiogen TMP, Catiogen TMS, Catiogen DDM-PG, Catiogen BC-50, and Catiogen TBB manufactured by Daiichi Kogyo Co., Ltd., and Kotamin 24P, Kotamin 86P Concentrate, and Kotamin 86P Concentrate manufactured by Kao Corporation. Examples of such products include Lipoguard C-50, Lipoguard T-28, Lipoguard T-30, Lipoguard T-50, Lipoguard T-800, Lipoguard 16-29, Lipoguard 16-50E, Lipoguard 18-63, Lipoguard 22-80, Lipoguard CB-50, Lipoguard 210-80E, Lipoguard 2C-75, Lipoguard 2HP-75, and Lipoguard 2HP-80. Examples of such flakes include, but are not limited to, Poguard 2HP flakes, Lipoguard 2HT-75, Lipoguard 2HT flakes, Lipoguard 20-751, Lipoguard 41-50, TMAC-50, TPAH-40, TBAB-50A, TBAB-100A, TBAH-40, Lipoguard PH-100, BTMAC-50, BTMAC-100A, BTEAC-50, BTEAC-100A, BTBAC-50A, and the like.

[0185] The cationic surfactant may contain at least one compound represented by a primary or secondary alkanolamine skeleton, or may contain at least one compound represented by a monoalkanolamine skeleton. Primary monoalkanolamines are preferably lower alkanols having 1 to 4 carbon atoms, and specific examples include monoethanolamine and 2-aminoisobutanol. Secondary monoalkanolamines include N-methylethanolamine, 2-ethylaminoethanol, and isopropanolamine, although substances other than those listed above can also be used as appropriate. These monoalkanolamine compounds can be used alone or in appropriate combinations of two or more, and can also be mixed with water for use.

[0186] These cationic surfactants having a monoalkanolamine skeleton are preferably of the monoalkanolamine salt type which forms a salt with a halogen, and preferably form a salt with Cl-.

[0187] Examples of anionic surfactants include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate ester salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, and the like. Specific examples of these include dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, and dibutylphenylphenol disulfonate.

[0188] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylolamides, alkylalkanolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers. Of these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers are preferred.

[0189] Other surfactants that can be used include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; and biosurfactants such as spiculisporic acid, rhamnolipid, and lysolecithin.

[0190] These surfactants can be used alone or in combination of two or more. When a surfactant is added, the amount added is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and even more preferably 0.01 to 1% by mass, based on the total amount of the alkaline aqueous solution.

[0191] (Antifoaming Agent) The desorption treatment liquid may contain an antifoaming agent. When stirring or crushing the substrate during immersion, a large amount of foam may be generated, and if the foam remains, the foam may overflow during the plastic film recovery process. Furthermore, if a large amount of foam is entrained in the desorption treatment liquid during crushing of the substrate, the substrate may not be crushed to the desired size.

[0192] Compounds commonly used as defoaming agents include water-soluble organic solvents and nonionic surfactants with low HLB values ​​in the range of 1 to 3, but silicone compounds are particularly preferred because of their high defoaming ability, with emulsion-type and self-emulsifying silicone compounds being particularly preferred.

[0193] The antifoaming agent may be used alone or in combination of two or more kinds. The content of the antifoaming agent in the cleaning liquid usable in step 1 is preferably in the range of 0.01 to 5 wt %, more preferably in the range of 0.02 to 4 wt %, and even more preferably in the range of 0.03 to 3 wt %.

[0194] The target printed material is immersed in, for example, a treatment tank in an alkaline aqueous solution that has been heated or ultrasonically vibrated to a liquid temperature of 40 to 90° C. The heating method for adjusting the liquid temperature is not particularly limited, and known heating methods using heat rays, infrared rays, microwaves, etc. can be used. Ultrasonic vibration can be achieved, for example, by attaching an ultrasonic vibrator to the treatment tank and applying ultrasonic vibration to the warm water or alkaline aqueous solution.

[0195] Stirring the printed material when immersed in the alkaline aqueous solution is not essential and is optional, but stirring allows for more efficient swelling. It is preferable to keep the stirring speed at a level that does not cause foaming or the like even without the addition of an antifoaming agent. The stirring method is not particularly limited, and known methods can be used. Examples include a method of mechanically stirring the dispersion of the printed material contained in a treatment tank using a stirring blade, a method using ultrasound, a method using a device that can shake the entire container, a method using a wet crusher, a water jet stirring method using a water jet pump, and a bubbling method using an inert gas such as nitrogen gas. These methods may be used in combination to achieve efficient desorption.

[0196] The time for immersing the printed material in the alkaline aqueous solution varies depending on the composition of the printed material, but is generally in the range of 1 minute to 48 hours. In the present invention, it is not necessary for 100% of the printed layer in the printed material to be completely detached from the substrate. However, it is preferable that 60% by mass or more of the 100% by mass of the printed layer be detached, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Furthermore, the removal rate of the detachable primer layer after washing with water and drying is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more.

[0197] In the desorption step, the film may be immersed in the alkaline aqueous solution once or several times. That is, the film may be immersed once and then the separated film substrate may be recovered, or the film may be immersed several times and then the film substrate may be recovered. When the film is immersed multiple times in the desorption step, the concentration of the alkaline aqueous solution may be changed. During the desorption step, known steps such as washing with water and drying may be added as appropriate.

[0198] Furthermore, the alkaline aqueous solution promotes detachment of the plastic substrate by contacting the interface between the primer layer and other layers from the edge of the printed material. Therefore, it is preferable that the primer layer is exposed at the cross section. Therefore, it is more preferable to include a step of fragmenting the printed material by cutting or pulverizing.

[0199] The method for crushing the plastic film is not particularly limited, and any known method can be used. Crushing may be carried out in an air atmosphere in the absence of a liquid such as a solvent, or in water or a cleaning solution. When crushing in an air atmosphere, a dry crusher can be used. When crushing in water or a cleaning solution, a wet crusher can be used, which can crush and pressure-feed simultaneously. When a wet crusher is used, plastic films that are printed materials can be efficiently crushed.

[0200] The long side of the crushed substrate is not particularly limited, but in the case of a surface printing configuration in which an ink layer or a coating layer is formed on the surface of a plastic substrate, it is preferably 1 mm to 50 mm, more preferably 1 mm to 30 mm, and even more preferably 1 mm to 20 mm.

[0201] (Recovery Equipment) Plastic substrates or crushed substrate material can be recovered layer by layer. After separation, the separated plastic substrate and residues of printing ink, primer layer, etc. are floating or dissolved in the liquid. After removing these from the liquid, they can be separated using known methods such as flotation. The equipment and method for recovering the substrate or crushed substrate material are not particularly limited, but for example, a filter, a centrifuge, an automatic scraping bar screen, an inclined wire screen, a rotary drum screen, etc. can be used.

[0202] Furthermore, it is preferable to agitate the recovered substrate in a rinse solution for finish washing to remove any ink or other detached material that re-adheres to and remains on the plastic film that has been detached as a single layer. Removing even traces of ink remaining on the film surface can significantly improve the quality of the recycled pellets. The rinse solution is not particularly limited, and the aforementioned detachment treatment solution can be used as is, but it is preferable for it to contain an appropriate amount of organic solvent. The organic solvent preferably contains, for example, one or more water-soluble alcohols or water-soluble solvents with a flash point of 21°C or higher, and it is preferable for the cleaning solution to contain a so-called water-soluble solvent containing alcohols. The equipment and method for stirring in the rinse solution are not particularly limited, and known methods can be used. Specific examples include a device equipped with a motor with stirring blades that can stir the cleaning solution in a container, a device equipped with a device that generates ultrasound, a device that can shake the entire container, a wet crusher, a kneader, etc.

[0203] (Recovery and reuse of desorption treatment liquid) The desorption treatment liquid used in the desorption treatment step can be recycled after being recovered by supplying it to one or more recycling machines selected from a filter, a centrifuge, and an ultrafilter, and removing solids. Water, a rinse liquid, etc. can also be recycled in the same way. While wet crushing is being performed, the recycling process of water, desorption treatment liquid, rinse liquid, etc. can be continuously operated to separate solids from the water, washing liquid, and rinse liquid.

[0204] (Drying of Separated Plastics) The separated and recovered substrate material is dried (film fragments) by one or more methods selected from reduced pressure heating drying, hot air drying, pressurized compression drying, etc. to remove residual moisture. As a pretreatment for producing recycled pellets (described below), after or during drying of the recovered film fragments, briquettes may be produced using a pressurized compressor such as a Nippon Seam compression dehydrator, a Oike Iron Works pellet mill, or an Elcom Stella or briquette machine. When plastic film is pulverized into powder using a wet grinder, the crushed material is pulverized to approximately 10 to 500 μm. Since the crushed material has a high density, the pressurized compression step can be omitted. The density varies depending on the material constituting the crushed material, but a higher density is preferable because it is easier to handle when passing it through a kneader. Specifically, a dry weight of 0.03 kg or more is preferred, 0.05 kg or more is more preferred, 0.2 kg or more is more preferred, and 0.3 kg or more is even more preferred.

[0205] (Preparation of Recycled Pellets) Dried film pieces or briquettes are fed into a single-screw or twin-screw extruder to prepare recycled pellets. When film pieces are fed directly into the extruder without a pressure compression process, a phenomenon known as bridging, in which ink pieces clog the inlet, is likely to occur. To avoid bridging, the film pieces may be pressurized in the feeder section or pushed in with air. To avoid bridging, the extruder body may use twin screws that rotate in opposite directions, or a side feeder may be used to push the material in. The kneader conditions are not particularly limited, but operation at 180 to 260°C is preferred to avoid significant deterioration of the resin performance before recycling. The printed matter of the present invention can be recycled as a recycled plastic product via the recycled pellets produced by the above-mentioned recycling method.

[0206] The present invention will be described in more detail below with reference to examples, in which parts, parts by mass, and % represent % by mass.

[0207] (Synthesis of Acrylic Resin) [Synthesis Example 1: Preparation of Shell Acrylic Resin (Polymer a1)] A reaction vessel was equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, and 60.0 parts by mass of n-propyl acetate was charged. The reaction vessel was heated to 90°C while stirring under a nitrogen atmosphere. Meanwhile, 25.0 parts by mass of methyl methacrylate, 61.0 parts by mass of n-butyl acrylate, 14.0 parts by mass of acrylic acid, and 1.0 part by mass of azobisisobutyronitrile were dissolved in 40.0 parts by mass of n-propyl acetate, and added dropwise using a dropping funnel over 4 hours. After the addition was completed, the reaction was continued for an additional 6 hours. After the reaction was completed, the mixture was cooled, and 8.0 parts by mass of 30% by mass ammonia water was added to the resulting acrylic resin solution to neutralize it. Ion-exchanged water was then added, and the solvent was replaced while heating, yielding an aqueous solution of acrylic resin (a1) with a solids content of 50% by mass. The acid value was 109 mgKOH / g, the Tg was -12.0°C, and the weight average molecular weight was 16,000.

[0208] Synthesis Example 2: Preparation of Core-Shell (Meth)acrylic Emulsion (No. 1) A reaction vessel containing 39.5 parts by mass of the acrylic resin aqueous solution (a1) prepared in Synthesis Example 1 was equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, and 230.0 parts by mass of ion-exchanged water was added. The reaction vessel was heated to 75°C while stirring under a nitrogen atmosphere. Next, using the dropping funnel, 15.5 parts by mass of n-butyl methacrylate, 5.0 parts by mass of 2-ethylhexyl methacrylate, 39.5 parts by mass of 2-ethylhexyl acrylate, and 3.3 parts by mass of 30% ammonium persulfate were added dropwise over 4 hours. After completion of the dropwise addition, the reaction was continued for an additional 6 hours, yielding a core-shell acrylic emulsion (No. 1) with a solids content of 40% by mass. The acid value was 42 mgKOH / g, Tg was −22°C, and weight-average molecular weight was 1,200,000.

[0209] Synthesis Example 3: Preparation of Solution-Type (Meth)acrylic Resin (No. 16) A reaction vessel was equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, and charged with 65.0 parts by mass of n-propyl acetate. The reaction vessel was heated to 90°C while stirring under a nitrogen atmosphere. Meanwhile, 10.0 parts by mass of methyl acrylate, 20.0 parts by mass of n-butyl acrylate, 45.0 parts by mass of methyl methacrylate, 15.0 parts by mass of 2-ethylhexyl methacrylate, 10.0 parts by mass of acrylic acid, and 1.6 parts by mass of azobisisobutyronitrile were dissolved in 35.0 parts by mass of n-propyl acetate and added dropwise using a dropping funnel over 4 hours. After completion of the dropwise addition, the mixture was allowed to react for an additional 6 hours. After completion of the reaction, the mixture was cooled, and the resulting acrylic resin solution was neutralized by adding 10.0 parts by mass of 30% by mass ammonia water. Ion-exchanged water was then added and the mixture was heated to replace the solvent, yielding a solution-type acrylic resin (No. 16) that was an aqueous solution of acrylic resin with a solid content of 30% by mass. The acid value was 42 mgKOH / g, the Tg was 79°C, and the weight-average molecular weight was 10,000.

[0210] Acrylic emulsions Nos. 1 to 6, 8 to 15, and 20 to 27, and acrylic resins Nos. 17 to 19 were prepared in the same manner as above, except that the type and amount of the radically polymerizable unsaturated monomer were appropriately changed so as to achieve the acid value and Tg shown in Table 1. For acrylic emulsion No. 7, Seiko PMC's acrylic core-shell emulsion resin "Hiros-X QE-2128" was used.

[0211]

[0212] [Alkali Solubility] The alkali solubility of the (meth)acrylic resin obtained above was evaluated by the following procedure. 3 g of the resin component (as solids) was added to 100 g of a 2% by mass aqueous sodium hydroxide solution heated to 70°C, stirred for 5 minutes, and then left to stand for 1 day while maintaining the temperature of the aqueous solution at 70°C. The aqueous solution after 1 day was adjusted to room temperature (25°C), and the NTU (Nephelometric Turbidity Unit) was measured using a Lovibond TB 300 IR turbidity meter (manufactured by Tintmaker). The aqueous solution was also filtered through Whatman FILTER PAPER No. 1 (manufactured by Cytiva), and the remaining resin component and precipitates resulting from the room temperature were visually confirmed. If the turbidity was 50 NTU or more or if there was any remaining residue, the resin component was determined to be alkali-insoluble. When the turbidity was less than 50 NTU and there was no undissolved resin component or precipitates due to being cooled to room temperature, the resin component was determined to be alkali-soluble.

[0213] [Preparation of Primer Composition] Primer composition 1 was prepared as follows. Acrylic resin 1 was diluted with isopropyl alcohol (IPA) / water = 30 / 70 to a solids content of 20%, and 1 part of Surfynol 420 was added to 100 parts by mass of the diluted solution to prepare primer composition 1. Primer compositions 2 to 27 were prepared using the corresponding acrylic resins 2 to 27 in the same manner as primer composition 1.

[0214] [Preparation of Solvent-Based Ink 1] A blue liquid printing ink was prepared by kneading a mixture (100 parts in total) of 37 parts by mass of N-propyl acetate (normal propyl acetate), 10 parts by mass of ethyl acetate, 11 parts by mass of indigo pigment, 10 parts by mass of industrial nitrocellulose H1 / 2 solution (nitrocellulose, solids content 70%, viscosity at 25.0% solution concentration 9.0 to 14.9% according to JIS K-6703, manufactured by Taihei Chemical Products Co., Ltd., adjusted to 50% solids content with IPA), 6 parts by mass of isopropyl alcohol, 1 part by mass of dispersant, 20 parts by mass of acrylic resin "Acrydic WCL-1419 manufactured by DIC Corporation, weight average molecular weight 35,000," and 5 parts by mass of cellulose acetate propionate. To 100 parts by mass of the resulting mixture, 42 parts by mass of an IPA / EtAc mixed solvent (isopropyl alcohol / ethyl acetate = 50 / 50 (parts by mass / parts by mass)) was added so that the mixture would be heated for approximately 15 seconds (25°C) using a Zahn cup #3 (manufactured by Rigo Co., Ltd.), thereby preparing solvent-based ink 1.

[0215] [Preparation of Solvent-Based Ink 2] A blue liquid printing ink was prepared by kneading a mixture (100 parts in total) of 40 parts by weight of N-propyl acetate (normal propyl acetate), 10 parts by weight of ethyl acetate, 11 parts by weight of indigo pigment, 3 parts by weight of vinyl chloride-vinyl acetate resin (vinyl chloride-vinyl acetate copolymer resin), 6 parts by weight of isopropyl alcohol, 1 part by weight of dispersant, and 29 parts of urethane resin (product name: Burnock ECL-341, weight average molecular weight 85,000). 42 parts by weight of an IPA / EtAc mixed solvent (isopropyl alcohol / ethyl acetate = 50 / 50 (parts by weight / parts by weight)) was added to 100 parts by weight of the resulting mixture so that the mixture was heated for approximately 15 seconds (25°C) in a Zahn cup #3 (manufactured by Rigo Co., Ltd.), to prepare Solvent-Based Ink 2.

[0216] [Preparation of Solvent-Based Ink 3] A white liquid printing ink was prepared by kneading a mixture (100 parts in total) of 20 parts by weight of N-propyl acetate (normal propyl acetate), 10 parts by weight of ethyl acetate, 38 parts by weight of white pigment, 10 parts by weight of polyvinyl butyral resin, 6 parts by weight of isopropyl alcohol, 1 part by weight of dispersant, 10 parts by weight of urethane resin (product name: Burnock ECL-341, weight average molecular weight 85,000), and 5 parts by weight of cellulose acetate propionate. 42 parts by weight of an IPA / EtAc mixed solvent (isopropyl alcohol / ethyl acetate = 50 / 50 (parts by weight / parts by weight)) was added to 100 parts by weight of the resulting mixture so that the mixture was heated for approximately 15 seconds (25°C) in a Zahn Cup #3 (manufactured by Rigo Co., Ltd.), to prepare Solvent-Based Ink 3.

[0217] [Preparation of Water-Based Ink 1] A mixture (total 100 parts by mass) of 20 parts by mass of core-shell acrylic emulsion "Hiros X-436 manufactured by Seiko PMC Corporation" converted to solids, 40 parts by mass of titanium oxide, 1 part by mass of Surfynol 420, 5 parts by mass of polyethylene wax, 3 parts by mass of normal propanol, 0.1 part by mass of antifoaming agent, 0.6 parts by mass of ammonia water, and 30.3 parts by mass of water was kneaded to prepare white water-based ink 1. The viscosity of the resulting water-based ink 1 was confirmed to be 16 seconds (25°C) using a Zahn cup #4 (manufactured by Rigo Co., Ltd.).

[0218] [Preparation of Printed Material] (Example 1) The printed material used in Example 1 was prepared as follows. The substrate film used was an OPP film ("Pylen P2161 20 μm" manufactured by Toyobo Co., Ltd.). The removable primer layer was prepared as follows. Primer composition 1 was printed onto a substrate film that had been corona discharge treated on one side, using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) equipped with a gravure plate having a plate depth of 22 μm. The resulting coating was dried at room temperature for one day. The printed layer was prepared as follows. Solvent-based ink 1 was printed using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) equipped with a gravure plate having a plate depth of 22 μm. The resulting printed material was dried at room temperature for one day. This gave the printed material of Example 1, which was laminated with the substrate, primer layer, and printing layer.

[0219] (Examples 2 to 228, Comparative Examples 1 to 96) Except for changing the base film, detachable primer layer, and printed layer as shown in the table, printed materials of Examples 2 to 228 and Comparative Examples 1 to 96 were produced in the same manner as Example 1. Note that the base film in the table is "Space Clean S-7053 40 μm" manufactured by Toyobo Co., Ltd. for s-PET and "Hybrid Styrene Sheet Film 40 μm" for HyOPS.

[0220] <Removal Method of Printed Matter> The printed matters of Examples 1 to 228 and Comparative Examples 1 to 96 were subjected to the following releasability test.

[0221] <Evaluation of Desorption Property> <<Alkaline Solution>> A desorption test was carried out under each of the following conditions, and the ease of desorption under each condition was compared. Release property 1: 1.5% by mass of sodium hydroxide, no surfactant, 85°C, pH 13.2 Release property 2: 1.5% by mass of sodium hydroxide, no surfactant, 55°C, pH 13.2 Release property 3: 0.5% by mass of sodium hydroxide, no surfactant, 55°C, pH 13.0 Release property 4: 0.1% by mass of sodium hydroxide, no surfactant, 55°C, pH 12.3 Release property 5: 1.5% by mass of sodium hydroxide, no surfactant, 30°C, pH 13.2 Release property 6: 1.5% by mass of sodium hydroxide, 0.3% by mass of nonionic surfactant, 30°C, pH 13.2 Release property 7: 0.5% by mass of sodium hydroxide, 0.3% by mass of nonionic surfactant, 55°C, pH 13.0 Release property 8: 0.1% by mass of sodium hydroxide, 0.3% by mass of nonionic surfactant, 55°C, pH 12.3 Release property 9: 1.5% by mass of sodium hydroxide, 0.3% by mass of nonionic surfactant, 30°C, pH 13.2 Release property 10: 0.005% by mass of sodium hydroxide, 0.3% by mass of cationic surfactant, 55°C, pH 10.5

[0222] <<Desorption test conditions>> The printed matter was cut into a size of 20 mm x 20 mm to obtain a test piece. The test piece was immersed in the solution and stirred with a stirrer. After stirring, the state of desorption was confirmed, and then the printed matter was rubbed with a finger to see if rubbing would cause the coating film to desorb. The releasability of the ink coating under the above conditions was evaluated according to the following evaluation criteria. [Evaluation criteria] 5: Complete desorption of the ink coating was confirmed within 15 minutes of stirring. 4: Complete desorption of the ink coating was confirmed with 15 to 30 minutes of stirring. 3: Complete desorption of the ink coating was confirmed with 30 to 60 minutes of stirring. 2: Partial desorption of the ink coating was confirmed with 60 minutes of stirring. Approximately 50 to 100% desorbed when rubbed with a finger. 1: No desorption of the ink coating was confirmed with 60 minutes of stirring. When rubbed with a finger, approximately 0 to 50% of the material was released. Regarding the above evaluation results, a level of 3 or higher is preferable in practice, but even a level of 2 is still sufficient to contribute to recycling, so a level of 2 or higher can be judged to be acceptable. As an exception, in the evaluation under the condition of release property 5, alkali resistance at room temperature is evaluated, so a level of 1 is most preferable, and a level of 3 or lower is a practical level.

[0223] [Adhesion] For the printed materials of Examples 1 to 228 and Comparative Examples 1 to 96, cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface, and then the tape was quickly peeled off, and the condition of the printed surface was visually evaluated. (Evaluation criteria) 5: The printed film did not peel off at all from the film. 4: Less than 15% of the area of ​​the printed film peeled off from the film. 3: Less than 30% of the area of ​​the printed film peeled off from the film. 2: Less than 50% of the area of ​​the printed film peeled off from the film. 1: 50% or more of the area of ​​the printed film peeled off from the film.

[0224] [Rubbing resistance] The printed matter of Examples 1 to 228 and Comparative Examples 1 to 96 was rubbed on black fine paper as the printed surface, and evaluated using a commercially available Gakushin-type rub fastness tester, with the rubbed paper rubbed 100 times with a load of 500 g. (Evaluation criteria) 5: No color transfer to the rubbed black fine paper. 4: Very light color transfer to the rubbed black fine paper. 3: Light color transfer to the rubbed black fine paper, but within the practical range. 2: Color transfer to the rubbed black fine paper. 1: Dark color transfer to the rubbed black fine paper.

[0225] [Scratch Resistance] For the printed materials of Examples 1 to 228 and Comparative Examples 1 to 96, the printed surface was rubbed back and forth with a fingernail 20 times, and the state of ink peeling was visually evaluated. (Evaluation Criteria) 5: The printed film did not peel off at all from the film. 4: Less than 15% of the area of ​​the printed film peeled off from the film. 3: Less than 30% of the area of ​​the printed film peeled off from the film. 2: Less than 50% of the area of ​​the printed film peeled off from the film. 1: 50% or more of the area of ​​the printed film peeled off from the film.

[0226] [Blocking resistance] The printed surfaces of the printed materials of Examples 1 to 228 and Comparative Examples 1 to 96 were placed together and left for one day under conditions of pressure: 0.5 MPa, temperature: 50°C, and humidity: 80% using a blocking tester, before being peeled off. The resistance to peeling and the state of peeling on the surface were evaluated. (Evaluation criteria) 5: The printed surfaces peeled off without resistance and there were no particular problems with the surfaces. 4: There was some resistance when peeling the printed surfaces, but there were no particular problems with the surfaces. 3: There was some resistance when peeling the printed surfaces, and it was clear that they were slightly stuck together. 2: There was resistance when peeling the printed surfaces, and it was clear that the surfaces were also stuck together. 1: There was considerable resistance when peeling the printed surfaces, and it was clear that the surfaces were also strongly stuck together.

[0227] [Shrinkage Suitability] Primer coated products 1 to 27, in which primer compositions 1 to 27 were applied to a substrate, were partially fixed to a stainless steel plate, immersed in hot water at 90°C for 20 seconds to shrink, and then dried. The haze value of the dried coating film was measured using a turbidity meter "NDH5000" (manufactured by Nippon Denshoku Industries Co., Ltd.). The method for applying the primer composition was the same as the method for preparing a removable primer layer in the production of printed matter. Haze value = diffuse transmittance (DF) / total light transmittance (T.T) 5: Haze value of 0% or more but less than 10% 4: Haze value of 10% or more but less than 20% 3: Haze value of 20% or more but less than 40% 2: Haze value of 40% or more but less than 60% 1: Haze value of 60% or more A rating of 3 or more is practically preferred. A rating of 4 or more is more preferred.

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235]

[0236]

[0237] As shown in the table, printed materials including a detachable primer layer formed using the detachable primer composition of the present invention in Examples 1 to 228 exhibited detachment performance at high temperatures and low alkali concentrations, and alkali resistance at low temperatures. Furthermore, it was found that the detachable primer composition of the present invention can exhibit adhesion, abrasion resistance, scratch resistance, blocking resistance, and shrinkage suitability equivalent to conventional inks. In particular, printed materials (Examples 1 to 48) having primer layers formed using Primers 1 to 4 containing (meth)acrylic resins with acid values ​​of 10 to 50 mgKOH / g and glass transition temperatures (Tg) of -30 to 20°C exhibited excellent detachability, alkali resistance, adhesion, abrasion resistance, scratch resistance, blocking resistance, and shrinkage suitability. On the other hand, printed materials (Comparative Examples 1 to 24) having primer layers formed using Primers 20 to 21 containing (meth)acrylic resins with acid values ​​of less than 10 mgKOH / g did not exhibit detachment performance regardless of the alkali concentration or liquid temperature. Printed materials (Comparative Examples 25 to 48) having primer layers formed with primers 22 to 23 containing a (meth)acrylic resin having a glass transition temperature (Tg) of less than -30°C had no problems with releasability and alkali resistance, but were particularly poor in abrasion resistance, scratch resistance, and blocking resistance. Printed materials (Comparative Examples 49 to 72) having primer layers formed with primers 24 to 25 containing a (meth)acrylic resin having a glass transition temperature (Tg) of more than 90°C had no problems with releasability and alkali resistance, but were particularly poor in adhesion. Printed materials (Comparative Examples 73 to 96) having primer layers formed with primers 26 to 27 containing a (meth)acrylic resin having an acid value of more than 90 mgKOH / g had poor alkali resistance at low temperatures.

Claims

1. A detachable primer composition for forming a detachable primer layer on a printed material having at least a plastic substrate, a detachable primer layer, and a printed layer laminated in this order, the detachable primer composition containing at least a (meth)acrylic resin and an aqueous solvent containing water as a main component, the (meth)acrylic resin having an acid value of 10 to 90 mgKOH / g and a glass transition temperature of -30°C to 90°C.

2. The detachment primer composition according to claim 1, wherein the (meth)acrylic resin is a homopolymer or copolymer of (meth)acrylate.

3. The detachment primer composition according to claim 1 or 2, wherein the (meth)acrylic resin is a (meth)acrylic resin emulsion having a core-shell structure.

4. A detachment primer composition according to claim 1 or 2, wherein the (meth)acrylic resin accounts for 50% or more of the total solid content of the composition.

5. The detachment primer composition according to claim 1 or 2, which does not contain a colorant.

6. The release primer composition according to claim 1, wherein the plastic substrate is a shrinkable film.

7. A printed matter comprising at least a plastic substrate, a detachable primer layer, and a printed layer laminated in this order, wherein the detachable primer layer is formed from a detachable primer composition, the detachable primer composition contains at least a (meth)acrylic resin and an aqueous solvent containing water as a main component, and the (meth)acrylic resin has an acid value of 10 to 90 mgKOH / g and a glass transition temperature of -30°C to 90°C.

8. A recycling method for recovering a plastic substrate from which a printed layer has been removed from a printed matter having at least a plastic substrate, a detachable primer layer, and a printed layer laminated in this order, wherein the detachable primer layer is formed from a detachable primer composition, the detachable primer composition contains at least a (meth)acrylic resin and an aqueous solvent having water as its main component, the (meth)acrylic resin has an acid value of 10 to 90 mgKOH / g and a glass transition temperature of -30°C to 90°C, and the printed matter is immersed in an alkaline aqueous solution to detach the printed layer from the plastic substrate.

9. The recycling method according to claim 8, wherein the temperature of the alkaline aqueous solution is 40°C or higher.

Images