Method for manufacturing a laminate and method for applying an adhesive

Abstract

To provide a method for manufacturing a laminate which is excellent in economical efficiency and environmental load reduction, and has no poor appearance such as orange peel.SOLUTION: A method for manufacturing a laminate having at least a base material 1, a printing layer having thickness distribution, an adhesive layer formed of a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent, and a base material 2 in this order, includes: a step 1 of coating the reactive adhesive onto a printing layer of a printed matter having at least a base material 1 and a printing layer having thickness distribution and / or the base material 2 so that a coating amount of the reactive adhesive is more than a part where the printing layer is thinner; and a step 2 of bonding the printing layer of the printed matter and the base material 2 through an adhesive layer formed of the reactive adhesive.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a laminate suitably used for packaging materials such as foods, pharmaceuticals, cosmetics, detergents, and sundries.

Background Art

[0002] As packaging materials for foods, clothing, cosmetics, sundries, etc., laminates obtained by multi-layer laminating various plastic films are widely used. Such a laminate is generally manufactured by forming a printing layer on a plastic film to produce a printed film, and then laminating the obtained printed film and another plastic film using an adhesive. The above printing layer is formed by a method such as on-demand printing such as inkjet printing in addition to gravure printing and flexographic printing, and often has a thickness distribution depending on the design of the printed matter. Further, as the laminate adhesive, a two-component reactive adhesive composed of a polyol component and a polyisocyanate component is the mainstream, and a urethane adhesive layer is formed. As a laminating method, it is common to apply an adhesive in a uniform coating amount over the entire surface of the printing layer by a known method, and then thermocompression bond the base film on the bonding side. In the above situation, for example, Patent Document 1 discloses a technique of using a two-component curable solventless adhesive having high reactivity but a short pot life by separately applying a polyol component and a polyisocyanate component onto a printing layer using an inkjet method.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the method described in Patent Document 1 applies the adhesive regardless of the design of the printing layer. Even for areas with a thin printing layer where there is little penetration of the adhesive, the adhesive is applied in the same manner as in areas with a thick printing layer. Therefore, the amount of adhesive applied is uniform across the entire surface of the substrate, and the same amount is applied to areas with a thin printing layer and areas with a thick printing layer. However, since the adhesive penetrates more easily in areas with a thick printing layer, an amount of laminate adhesive exceeding the amount required to exert adhesive force is applied to the entire printing layer including areas with a thin printing layer where the penetration of the adhesive is less. Therefore, improvement is desired from the viewpoints of economy and environmental load. And generally, since solventless adhesives are designed to have a low viscosity to impart coatability, there is a problem that appearance defects such as orange peel are likely to occur in areas with a thin printing layer (including plain areas). Therefore, an object of the present invention is to provide a method for manufacturing a laminate that is excellent in economy and reduction of environmental load and has no appearance defects such as orange peel.

Means for Solving the Problems

[0005] As a result of intensive studies to solve the above problems, it has been found that the above problems can be solved by the following embodiments, and the present invention has been completed.

[0006] An embodiment of the present invention is a method for manufacturing a laminate having at least a substrate 1, a printing layer having a thickness distribution, an adhesive layer formed from a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent, and a substrate 2 in this order, wherein on the printing layer of a printed matter comprising at least the substrate 1 and the printing layer having a thickness distribution, and / or on the substrate 2, a step 1 of applying the reactive adhesive such that the amount of the reactive adhesive applied is larger in areas where the printing layer is thick than in areas where it is thin, and a step 2 of bonding the printing layer of the printed matter and the substrate 2 via the adhesive layer formed from the reactive adhesive.

[0007] Another embodiment of the present invention relates to a method for manufacturing the above laminate, wherein the reactive adhesive is applied by a coating method including at least one selected from the group consisting of an inkjet coating method and a spray coating method.

[0008] Another embodiment of the present invention relates to the method for manufacturing the above laminate, wherein step 1 includes: step a1 of applying the reactive adhesive onto the printing layer of a printed matter including the base material 1 and a printing layer having a thickness distribution, and / or onto the entire surface of the base material 2; and step a2 of applying the reactive adhesive onto the printing layer of the printed matter including the base material 1 and a printing layer having a thickness distribution, and / or onto the portion with a thick printing layer thickness on the base material 2.

[0009] Another embodiment of the present invention relates to the method for manufacturing the above laminate, wherein step a1 is performed by a gravure coating method or a spray coating method, and step a2 is performed by an inkjet coating method.

[0010] Another embodiment of the present invention relates to the method for manufacturing the above laminate, wherein step 1 includes step b1 of applying the reactive adhesive onto the printing layer of a printed matter including at least the base material 1 and a printing layer having a thickness distribution, and / or onto the base material 2 by using an inkjet coating method.

[0011] Another embodiment of the present invention relates to an adhesive coating method for applying a reactive adhesive including a polyol main agent and a polyisocyanate curing agent onto the printing layer of a printed matter having at least the base material 1 and a printing layer having a thickness distribution, the method including a step of applying the reactive adhesive such that the application amount of the reactive adhesive is larger at a portion with a thick printing layer thickness than at a portion with a thin printing layer thickness.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a method for manufacturing a laminate that is excellent in economy and reduction of environmental load and has no appearance defects such as fish-scale skin.

Modes for Carrying Out the Invention

[0013] <Method for manufacturing a laminate> The present invention relates to a method for manufacturing a laminate having at least a substrate 1, a printed layer having a thickness distribution, an adhesive layer formed from a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent, and a substrate 2 in this order. On the printed layer of a printed matter including at least the substrate 1 and the printed layer having a thickness distribution, and / or on the substrate 2, a step 1 of applying the reactive adhesive so that the application amount of the reactive adhesive is larger at a thick portion of the printed layer than at a thin portion; and a step 2 of bonding the printed layer of the printed matter and the substrate 2 via the adhesive layer formed from the reactive adhesive. By adjusting the application amount according to the thickness of the printed layer, it is possible to obtain a laminate that is excellent in economy and reduction of environmental load without applying an excessive amount of adhesive to a thin portion of the printed layer and has no appearance defects such as a smooth surface. Hereinafter, the present invention will be described in detail.

[0014] <Step 1> In step 1, the method of applying the reactive adhesive is not particularly limited and can be appropriately selected from known coating methods. Examples of such coating methods include a gravure coating method, a flexo coating method, a roll coater coating method, an inkjet coating method, and a spray coating method. The coating method may use a single method alone or a combination of two or more methods. In the present invention, the application amount of the reactive adhesive varies according to the thickness of the printed layer, and the application is performed so that the application amount of the reactive adhesive is larger at a thick portion of the printed layer than at a thin portion. For example, when using the gravure coating method, the application amount of the adhesive can be adjusted in correlation with the thickness of the printed layer by using a gravure cylinder plate according to the design of the printed layer. Also, when using the inkjet coating method, the application amount of the adhesive can be adjusted on demand according to the design of the printed layer. In addition, the method of changing the application amount is not limited to the above, and can be appropriately selected from known methods such as a method of performing multiple coatings while changing the application range. Among them, the inkjet coating method is preferable because it is economically excellent.

[0015] In Step 1, the reactive adhesive is applied onto Substrate 1 and / or Substrate 2. That is, the reactive adhesive may be applied onto Substrate 1, may be applied onto Substrate 2, or may be applied onto both Substrate 1 and Substrate 2. As an example of applying onto both, for instance, the adhesive is applied only to the locations with a thick printing layer of Substrate 1 using an inkjet coating method, while on the other hand, the adhesive is applied to the entire surface of Substrate 2 using a gravure coating method. When the reactive adhesive is applied onto both Substrate 1 and Substrate 2, the coating amount of the adhesive represents the total coating amount onto both substrates.

[0016] A preferred embodiment of Step 1 includes Step a1 of applying the reactive adhesive onto the printing layer of a printed matter comprising Substrate 1 and a printing layer having a thickness distribution, and / or onto the entire surface of Substrate 2, and Step a2 of applying the reactive adhesive to the locations with a thick printing layer on the printing layer of a printed matter comprising Substrate 1 and a printing layer having a thickness distribution, and / or onto Substrate 2. After uniformly applying the reactive adhesive to the entire surface in Step a1, by applying the reactive adhesive only to the locations with a thick printing layer, the coating amount can be controlled, and the coating amount at the locations with a thick printing layer can be made more than the coating amount at the locations with a thin printing layer. Step a1 is preferably performed by a gravure coating method or a spray coating method, and Step a2 is preferably performed by an inkjet coating method.

[0017] Another preferred embodiment of Step 1 includes Step b1 of applying the reactive adhesive onto the printing layer of a printed matter comprising Substrate 1 and a printing layer having a thickness distribution, and / or onto the above-mentioned Substrate 2 using an inkjet coating method. By using the inkjet coating method, the coating amount can be easily controlled on demand according to the thickness of the printing layer, and the coating amount at the locations with a thick printing layer can be made more than the coating amount at the locations with a thin printing layer.

[0018] [Substrate 1] Substrate 1 used in the present invention is not particularly limited, and a film-like or sheet-like plastic substrate generally used for packaging materials can be used. These may also be laminated laminates. Examples of the plastic substrate include films of thermoplastic resins and thermosetting resins, and preferably films of thermoplastic resins. Examples of the thermoplastic resins include polyolefin resins, polyester resins, polyamide resins, polystyrene resins, vinyl chloride resins, vinyl acetate resins, AS resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, cellulose resins, and cellulose-based plastics.

[0019] More specifically, polyolefin resin films such as polyethylene (PE) and biaxially oriented polypropylene (OPP); polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polylactic acid (PLA); polystyrene resin films; polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; cellophane films; multilayers thereof (e.g., nylon 6 / MXD6 / nylon 6, nylon 6 / ethylene-vinyl alcohol copolymer / nylon 6) and mixtures; etc. are used. Among them, those having mechanical strength and dimensional stability are preferred. The plastic substrate may contain additives such as antistatic agents and ultraviolet absorbers as required, and may be provided with a vapor deposition layer of silica, alumina, etc.

[0020] When the substrate 1 is a laminate composed of a plurality of substrates, it is preferable that the substrates are laminated via an adhesive layer, and it may have a metal foil layer such as an aluminum foil layer. The method for forming the adhesive layer is not limited, and it can be formed by a known method using a known adhesive.

[0021] The thickness of the substrate 1 is preferably 5 μm or more and 200 μm or less, more preferably 10 μm or more and 100 μm or less, and still more preferably 10 μm or more and 50 μm or less. The surface of the substrate 1 may be subjected to corona treatment or low-temperature plasma treatment. Further, the base material 1 may have a coating layer such as an anchor coating or a primer coating in order to improve the adhesion to the printing layer described later.

[0022] [Printed matter] The printed matter in the present invention includes at least a base material 1 and a printing layer having a thickness distribution. The printing layer only needs to have a thickness distribution and may have a plain part. The method for forming the printing layer is not limited, and examples thereof include a gravure printing method, a flexographic printing method, a screen printing method, an offset printing method, an offset gravure method, a liquid electrophotography method (LEP), and an inkjet (IJ) method. The printing ink used for forming the printing layer is not particularly limited, and solvent-based ink, water-based ink, UV-curable ink, two-component curable ink, toner ink, etc. can be used. The thickness of the printing layer is not particularly limited, but generally, it is often adjusted in the range of 0.5 to 3 μm. The thickness of the printing layer can be appropriately changed according to the design.

[0023] [Adhesive layer] The adhesive layer in the present invention is formed from a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent, and is formed by applying the reactive adhesive on the printing layer of a printed matter including at least the base material 1 and a printing layer having a thickness distribution, and / or on the base material 2 such that the application amount of the reactive adhesive is larger at the thick portion of the printing layer than at the thin portion. That is, there is a positive correlation between the thickness of the printing layer and the application amount of the reactive adhesive. When a reactive adhesive composed of a polyol main agent and a polyisocyanate curing agent is applied onto a printing layer, the polyisocyanate curing agent penetrates into the printing layer. The amount of penetration increases as the thickness of the printing layer increases. If there is a large amount of the penetrating polyisocyanate curing agent, the polyisocyanate curing agent in the adhesive layer will be insufficient, resulting in insufficient curing. By making the thickness of the printing layer and the coating amount of the reactive adhesive in a positive correlation, it is possible to suppress insufficient curing at locations where the printing layer is thick, and not use excessive adhesive at locations where the printing layer is thin, thereby enhancing economy from the perspective of material cost and reducing the environmental load. The application of the reactive adhesive may be carried out continuously after forming the printing layer without winding the printed matter into a roll shape, or may be carried out after winding the printed matter into a roll shape.

[0024] Let the coating amount of the reactive adhesive at the location where the printing layer is thinnest be CW1 (g / m 2 : in terms of solid content), and the coating amount of the reactive adhesive at the location where the printing layer is thickest be CW2 (g / m 2 : in terms of solid content). In this case, the coating amount of the reactive adhesive preferably satisfies 0.5 < CW1 < CW2 < 5 (g / m 2 : in terms of solid content), more preferably further satisfies 1.0 < CW1 < 4 (g / m 2 : in terms of solid content), and 1.2 < CW2 < 5 (g / m 2 : in terms of solid content). The coating amount CW1 is preferably 1.0 to 2.5 g / m 2 and the coating amount CW2 is preferably 1.5 to 3.5 g / m 2 and CW2 / CW1 is preferably in the range of 1.1 to 6.0.

[0025] The adhesive layer in the present invention only needs to be formed from a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent. A mixture of the polyol main agent and the polyisocyanate curing agent may be applied, or the polyol main agent and the polyisocyanate curing agent may be applied separately. A method of applying a mixture of a polyol main agent and a polyisocyanate curing agent is preferably used, for example, in a gravure coating method, a flexographic coating method, or a roll coater coating method. A method of separately applying a polyol main agent and a polyisocyanate curing agent is preferably used, for example, in a gravure coating method, an inkjet coating method, a spray coating method, etc.

[0026] The polyol component contained in the polyol main agent is not particularly limited, and examples thereof include polyester polyol, polyester urethane polyol, polyether polyol, polyether urethane polyol, polycarbonate polyol, polycarbonate urethane polyol, polycaprolactone polyol, polycaprolactone polyurethane polyol, polyolefin polyol, and acrylic polyol. In addition, low molecular weight glycols such as ethylene glycol and propylene glycol, and vegetable oils containing hydroxyl groups such as castor oil can also be used. Among them, from the viewpoint of the adhesive strength of the laminate, polyester polyol, polyester urethane polyol, and polyether urethane polyol are preferred.

[0027] The polyisocyanate component contained in the polyisocyanate curing agent is not particularly limited. For example, aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatemethyl caproate; alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4′-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane; aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate or a mixture thereof, 4,4′-toluidine diisocyanate, dianisidine diisocyanate, 4,4′-diphenyl ether diisocyanate; aromatic aliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω′-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof; polyisocyanate monomers such as organic triisocyanates like triphenylmethane-4,4′,4″-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, and organic tetraisocyanates like 4,4′-diphenyldimethylmethane-2,2′-5,5′-tetraisocyanate;Examples of the polyisocyanate include dimers, trimers, biurets, allophanates, and polyisocyanates having a 2,4,6 - oxadiazinetrione ring obtained from carbon dioxide and the above polyisocyanate monomer, which are derived from the above polyisocyanate monomer.;

[0028] In addition, examples of the polyisocyanate component include adducts obtained by adding various glycol components shown below to the polyisocyanate monomer. Examples of the glycol component used for forming the adduct include low - molecular - weight polyols with a molecular weight of less than 200 such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6 - hexanediol, 3 - methyl - 1,5 - pentanediol, 3,3′ - dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, etc., polyesters with a molecular weight of 200 to 20,000, polyether esters, polyester amides, polycaprolactone polyols, polyvalerolactone polyols, acrylic polyols, polycarbonate polyols, polyhydroxyalkanes, castor oil, and polyurethane polyols.

[0029] The mixing ratio (NCO / OH (molar ratio)) of the polyol main agent and the polyisocyanate curing agent is not particularly limited, but is generally preferably in the range of 1.1 to 10. The NCO / OH ratio in the adhesive may be changed depending on the location of the printing layer or according to the thickness of the printing layer. The NCO / OH ratio in the adhesive in the region where the thickness of the printing layer is relatively thin is preferably in the range of 1.5 to 3.0, and the NCO / OH ratio in the adhesive in the region where the thickness of the printing layer is relatively thick is preferably in the range of 2.0 to 4.0. It is more preferable that the NCO / OH ratio in the adhesive in the region where the thickness of the printing layer is relatively thick is larger than the NCO / OH ratio in the adhesive in the region where the thickness of the printing layer is relatively thin. The adjustment of the NCO / OH ratio may be carried out, for example, when using an inkjet coating method, by adjusting the discharge amount of each of the head for discharging the main agent and the head for discharging the curing agent, or by increasing or decreasing the number of heads to adjust the discharge amount.

[0030] The reactive adhesive may be a solvent-free adhesive, or a solvent-based adhesive containing an organic solvent or water, or an aqueous adhesive. Preferably, it is a solvent-based adhesive containing an organic solvent or water or an aqueous adhesive. Further, the reactive adhesive may contain additives such as an antioxidant, an ultraviolet absorber, a fungicide, a plasticizer, and a lubricant as required. When containing an organic solvent or water, after applying the reactive adhesive, if necessary, the adhesive layer can be formed by drying the organic solvent or water with drying equipment such as a drying oven.

[0031] <Step 2> A laminate can be obtained by laminating and bonding the base material 1 and the base material 2 through a reactive adhesive layer. The method of bonding the base material 1 and the sealant base material 2 is not particularly limited and can be appropriately selected from known methods. A preferable such method is a method using a hot nip roll.

[0032] [Base material 2] Examples of the base material 2 used in the present invention include, in addition to the base materials mentioned above for the base material 1, a sealant base material, and a laminate in which these are laminated may also be used. Examples of the sealant base material include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), acid-modified polyethylene, unoriented polypropylene (CPP), acid-modified polypropylene, copolymerized polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate copolymer, ethylene-(meth)acrylic acid copolymer, and ionomer. The base material 2 is preferably a sealant base material and contains a polyolefin. The base material 2 may contain additives such as an antistatic agent and an ultraviolet inhibitor as required, and may be provided with a vapor deposition layer of aluminum, silica, alumina, or the like.

[0033] The thickness of the base material 2 is not particularly limited, and considering processability or heat sealability to the packaging container, etc., it is preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and 70 μm or less. The base material 2 may be provided with unevenness having a height difference of about several μm to impart slipperiness and tear resistance of the packaging material. The surface of the base material 2 may be subjected to corona treatment or low-temperature plasma treatment. Further, a sealant layer may be provided on the outermost layer of the base material 2, and the sealant layer may be either a heat sealant layer or a cold sealant layer.

[0034] Thus, by using the present invention, according to the design of the printing layer, the coating amount of the adhesive can be optimized, the economy can be improved from the viewpoint of material cost, and the environmental load can be reduced by eliminating excessive material use, which is useful in the field of packaging materials.

Examples

[0035] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the Examples and Comparative Examples, "parts" and "%" mean "parts by mass" and "mass %" unless otherwise specified.

[0036] <Preparation and Production of Reactive Adhesive> (Reactive Adhesive Ad1) 17 parts of solvent-based polyester polyol TM-569 (manufactured by Toyo Morton, solid content 62%), 0.8 parts of aliphatic isocyanate CAT-RT37 (manufactured by Toyo Morton, solid content 95%), and ethyl acetate were mixed to obtain a reactive adhesive Ad1 with a solid content of 30%.

[0037] (Main Agent A1) Solvent-based polyester polyol TM-569 (manufactured by Toyo Morton, solid content 62%) was diluted with ethyl acetate to obtain a main agent A1 with a solid content of 20%.

[0038] (Main Agent A2) 98 parts of Sunnex PP-200 (manufactured by Sanyo Chemical Industries, Ltd.) and 2 parts of Sunnex GP-250 (manufactured by Sanyo Chemical Industries, Ltd.) were mixed to obtain Main Agent A2.

[0039] (Hardener B1) Aliphatic isocyanate CAT-RT37 (manufactured by Toyo Morton, solid content 95%) was diluted with ethyl acetate to obtain Hardener B1 with a solid content of 5%.

[0040] (Hardener B2) Polymeric MDI Millionate MR-100 (manufactured by Tosoh Corporation) was used as Hardener B2.

[0041] (Preparation of Printing Ink) (Water-based Ink Set P1) (Preparation of Pigment Dispersions 1C, 1M, 1Y, 1K) 20 parts of C.I. Pigment Blue 15:3, 20 parts of varnish (solid content 25%) of a coloring agent dispersion resin (a water-soluble resin containing styrene, acrylic acid, and stearyl methacrylate as constituent units in a mass ratio of 25:40:35, having a weight-average molecular weight of 25,000 and an acid value of 185 mgKOH / g), and 60 parts of water were put into a mixing container and then well mixed with a stirrer. Next, dispersion was carried out using a Dyno Mill (bead mill manufactured by Simar Enterprises Co., Ltd.) with a volume of 0.6 L filled with zirconia beads having a diameter of 0.5 mm to obtain a cyan-colored pigment dispersion (designated as Pigment Dispersion 1C). Also, pigment dispersions of magenta, yellow, and black colors (designated as Pigment Dispersion 1M, Pigment Dispersion 1Y, and Pigment Dispersion 1K, respectively) were obtained in the same manner as Pigment Dispersion 1C, except that the pigments were changed to C.I. Pigment Red 122, C.I. Pigment Yellow 14, and carbon black, respectively.

[0042] (Preparation of Binder Resin 1) 72.4 parts of 2-butanone was charged into a reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer, and replaced with nitrogen gas. After heating the inside of the reaction vessel to 80 °C, a mixture of 4.5 parts of methacrylic acid, 5.0 parts of 2-hydroxyethyl methacrylate, 90.5 parts of methyl methacrylate, and 12 parts of V-601 (a polymerization initiator manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours to conduct a polymerization reaction. After completion of the dropwise addition, the reaction was further carried out at 80 °C for 3 hours, then 0.6 part of V-601 was added, and the reaction was continued at 80 °C for 2 hours to obtain a solution of binder resin 1 which is a hydrosol. The weight average molecular weight of the above binder resin 1 measured using GPC (HLC-8120GPC manufactured by Tosoh Corporation) equipped with a TSKgel column (manufactured by Tosoh Corporation) and an RI detector and using THF as a developing solvent was about 7,000. After cooling the solution of the above binder resin 1 to 50 °C, 4.7 parts of dimethylaminoethanol was added for neutralization, and then 140 parts of water was added. Then, the inside of the reaction vessel was heated to 78 °C or higher, 2-butanone was distilled off by azeotroping with water, and then adjusted with water so that the solid content became 30% to obtain a varnish of binder resin 1. The acid value and hydroxyl value of binder resin 1 calculated from the constitutional units of the resin were 29.3 mgKOH / g and 21.6 mgKOH / g, respectively. Also, the glass transition temperature (Tg) measured using DSC (DSC6000 manufactured by PerkinElmer) was 103 °C.

[0043] 〔Preparation of Aqueous Ink Set P1〕 20 parts of pigment dispersion liquid 1C, 21 parts of the varnish of binder resin 1 (solid content 30%), 25 parts of 1,2-propanediol, 1 part of Surfynol 465 (an acetylene-based surfactant manufactured by Shin-Etsu Chemical Co., Ltd.), 0.1 part of Proxel GXL (a preservative manufactured by Lonza), and 32.9 parts of water were sequentially charged into a mixing container. Next, after heating the inside of the mixing container to 50 °C, it was mixed with a stirrer for 1 hour. Then, filtration was performed using a depth type filter with a pore size of 1 μm to remove coarse particles, thereby obtaining a cyan aqueous ink (referred to as ink 1C). In addition, aqueous inks of magenta, yellow, and black colors (referred to as Ink 1M, Ink 1Y, and Ink 1K, respectively) were obtained in the same manner as Ink 1C, except that the pigment dispersion was changed to Pigment Dispersion 1M, Pigment Dispersion 1Y, and Pigment Dispersion 1K, respectively. The four-color inks of Ink 1C, Ink 1M, Ink 1Y, and Ink 1K thus prepared were used as the aqueous ink set P1.

[0044] <Manufacture of laminate> (Example 1) Using a gravure two-color printing press, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were coated in this order on polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was coated on a part of the PET, and the white ink was coated on the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. After forming the printed layer, continuously, a reactive adhesive Ad1 was coated on the printed layer by a gravure coating method, and the solvent was dried in a drying oven. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded with a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, obtaining a laminate having a structure of PET / printed layer / adhesive layer / LLDPE. The gravure cylinder used for coating the adhesive had different line number patterns formed at the overlapping part of blue / white and the part where only white was printed in the printed layer. A pattern with a 110-line grid pattern at the overlapping part of blue / white and a 150-line grid pattern at the part where only white was printed was used. The coating amount of the reactive adhesive at the overlapping part of blue / white was 3.5 g / m 2 (in terms of solid content), and the coating amount of the reactive adhesive at the part where only white was printed was 2.5 g / m 2 (in terms of solid content).

[0045] (Example 2) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were applied in this order onto polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was applied to a part of the PET, and the white ink was applied to the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. After forming the printed layer, continuously, a reactive adhesive Ad1 was applied onto the above printed layer by a gravure coating method, and the solvent was dried in a drying oven. After drying the solvent, continuously, by an inkjet coating method, the main agent A1 was ejected from the first inkjet head to the overlapping part of blue / white of the printed layer, and further, the curing agent B1 was ejected from the second inkjet head to the overlapping part of blue / white of the printed layer, and the solvent was dried in a drying oven. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded with a nip roll at 50°C and aged in an oven at 40°C for 4 days to cure the adhesive layer, and a laminate having a structure of PET / printed layer / adhesive layer / LLDPE was obtained. As the gravure cylinder used for applying the adhesive, one with a 150-line grid pattern formed on the entire surface was used. As the inkjet head, KJ4C-0360 (manufactured by Kyocera) was used. The application amount of the reactive adhesive at the overlapping part of blue / white of the printed layer was 3.5 g / m 2 (in terms of solid content), and the application amount of the reactive adhesive at the part where only white was printed on the printed layer was 2.5 g / m 2 (in terms of solid content).

[0046] (Example 3) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were applied in this order onto polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was applied to a part of the PET, and the white ink was applied to the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. After forming the printing layer, successively, on the printing layer, a reactive adhesive Ad was applied by a spray coating method, and after drying the solvent in a drying oven, by an inkjet coating method, from a first inkjet head, the main agent A1 was ejected onto the portion where the blue / white of the printing layer overlapped, and further, from a second inkjet head, the curing agent B1 was ejected onto the portion where the blue / white of the printing layer overlapped, and the solvent was dried in a drying oven. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded with a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, and a laminate having a structure of PET / printing layer / adhesive layer / LLDPE was obtained. As the inkjet head, KJ4C-0360 (manufactured by Kyocera) was used. The application amount of the reactive adhesive at the portion where the blue / white of the printing layer overlapped was 3.5 g / m 2 (in terms of solid content), and the application amount of the reactive adhesive at the portion where only the white of the printing layer was printed was 2.5 g / m 2 (in terms of solid content).

[0047] (Example 4) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were successively coated on polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was coated on a part of the PET, and the white ink was coated on the entire surface to form a printing layer having a thickness distribution. The thickness at the portion where the blue / white overlapped was 1.5 μm, and the thickness at the portion where only the white was printed was 1 μm. After forming the printing layer, successively, on the printing layer, as an inkjet coating method, from a first inkjet head, the main agent A1, and further, from a second inkjet head, the curing agent B1 were ejected with different ejection amounts at the portion where only the white of the printing layer was printed and the portion where the blue / white of the printing layer overlapped, and the solvent was dried in a drying oven. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded with a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, and a laminate having a structure of PET / printing layer / adhesive layer / LLDPE was obtained. The inkjet head used was KJ4C-0360 (manufactured by Kyocera). The application amount of the reactive adhesive at the overlapping part of the blue / white of the printing layer was 3.5 g / m 2 (in terms of solid content), and the application amount of the reactive adhesive at the part where only white of the printing layer was printed was 2.5 g / m 2 (in terms of solid content).

[0048] (Examples 5 and 6) In Example 4, a laminate was obtained in the same manner as in Example 4, except that the application amount at the overlapping part of the blue / white of the printing layer and the application amount at the part where only white of the printing layer was printed were changed as shown in Table 1.

[0049] (Example 7) In Example 2, a laminate was obtained in the same manner as in Example 2, except that the printing method was changed to the flexographic printing method and the inks were changed to the white ink and blue ink (manufactured by Toyo Ink Co., Ltd.) of Aqua Ecoal. The residual moisture at the part where only white of the printing layer of Aqua Ecoal was printed was 4.8 g / m 2 , and the residual moisture at the overlapping part of the blue / white of the printing layer was 7.3 g / m 2 .

[0050] (Example 8) In Example 2, the printing method was changed to the inkjet printing method and the ink was changed to Ink Set P1. Magenta was printed on the entire surface of the substrate at a printing rate of 150%, and further, on a part of the substrate, yellow, cyan, and black were overlaid at a printing rate of 50% each to make a printing rate of 300% and printed. A laminate was obtained in the same manner as in Example 2, except that a printed matter with a thickness distribution was produced. The thickness at the part where only magenta was printed was 0.8 μm, and the thickness at the part where magenta, yellow, cyan, and black were overprinted was 1.7 μm.

[0051] (Example 9) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were coated in this order on polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was coated on a part of the PET, and the white ink was coated on the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. Thereafter, the polyethylene terephthalate (PET) on which the printed layer was formed in a roll shape was unwound again, and a reactive adhesive Ad1 was applied on the above printed layer by a gravure coating method, and the solvent was dried in a drying oven. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded with a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, and a laminate having a structure of PET / printed layer / adhesive layer / LLDPE was obtained. The gravure cylinder used for applying the adhesive has different line number patterns formed at the overlapping part of blue / white and the part where only white was printed in the printed layer. A pattern with a 110-line grid pattern was formed at the overlapping part of blue / white, and a pattern with a 150-line grid pattern was formed at the part where only white was printed. The application amount of the reactive adhesive at the overlapping part of blue / white was 3.5 g / m 2 (in terms of solid content), and the application amount of the reactive adhesive at the part where only white was printed was 2.5 g / m 2 (in terms of solid content).

[0052] (Example 10) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were coated in this order on polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was coated on a part of the PET, and the white ink was coated on the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. After that, the polyethylene terephthalate (PET) with the printed layer wound in a roll was unwound again, and on the said printed layer, as an inkjet coating method, from the first inkjet head, the main agent A1, and from the second inkjet head, the curing agent B1 were discharged only to the overlapping part of blue / white, and the solvent was dried in a drying oven. Next, the reactive adhesive Ad1 was applied by a gravure coating method onto linear low-density polyethylene (LLDPE) with a thickness of 100 μm, and the solvent was dried in a drying oven. Next, the reactive adhesive surface composed of the main agent A1 and the curing agent B1 formed on the polyethylene terephthalate (PET) and the Ad1 surface formed on the linear low-density polyethylene (LLDPE) were pressure-bonded with a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, and a laminate having a structure of PET / printed layer / adhesive layer / LLDPE was obtained. As the gravure cylinder used for applying the adhesive, one with a 150-line grid pattern formed over the entire surface was used. As the inkjet head, KJ4C-0360 (manufactured by Kyocera) was used. The application amount of the reactive adhesive (that is, the total of the reactive adhesive Ad1, the main agent A1, and the curing agent B1) was 3.5 g / m 2 (in terms of solid content) at the overlapping part of blue / white, and 2.5 g / m 2 (in terms of solid content) at the part where only white was printed.

[0053] (Example 11) A laminate was obtained in the same manner as in Example 1, except that the polyethylene terephthalate (PET) with a thickness of 12 μm in Example 1 was changed to an MDO PE Film (manufactured by Windmiller) with a thickness of 12 μm.

[0054] (Comparative Example 1) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were applied in this order onto polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was applied to a part of the PET, and the white ink was applied to the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. After forming the printed layer, continuously, a reactive adhesive Ad1 was applied onto the above printed layer by a gravure coating method, and the solvent was dried in a drying oven. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded with a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, obtaining a laminate having a structure of PET / printed layer / adhesive layer / LLDPE. The gravure cylinder used for applying the adhesive forms different line number patterns at the overlapping part of blue / white and the part where only white is printed in the printed layer. A pattern with a 180-line grid type at the overlapping part of blue / white and a 110-line grid type at the part where only white is printed was used. The application amount of the reactive adhesive at the overlapping part of blue / white was 1.5 g / m 2 (in terms of solid content), and the application amount of the reactive adhesive at the part where only white is printed was 3.5 g / m 2 (in terms of solid content).

[0055] (Comparative Example 2) Using a gravure two-color printing machine, LP Bio blue ink (manufactured by Toyo Ink Co., Ltd.) and LP Bio white ink (manufactured by Toyo Ink Co., Ltd.) were applied in this order onto polyethylene terephthalate (PET) with a thickness of 12 μm. The blue ink was applied to a part of the PET, and the white ink was applied to the entire surface to form a printed layer having a thickness distribution. The thickness at the overlapping part of blue / white was 1.5 μm, and the thickness at the part where only white was printed was 1 μm. After forming the printed layer, continuously, from the first inkjet head, main agent A2 and further from the second inkjet head, curing agent B2 were ejected onto the entire surface of the above printed layer by an inkjet coating method. Next, linear low-density polyethylene (LLDPE) with a thickness of 100 μm was pressure-bonded using a nip roll at 50 °C and aged in an oven at 40 °C for 4 days to cure the adhesive layer, obtaining a laminate with a structure of PET / printing layer / adhesive layer / LLDPE. An inkjet head, KJ4C-0360 (manufactured by Kyocera), was used. The coating amount of the reactive adhesive was 3.5 g / m 2 (in terms of solid content) both at the overlapping part of blue / white in the printing layer and at the part where only white in the printing layer was printed.

[0056] [Evaluation of the laminate] For the obtained laminate, the laminate appearance, laminate strength, and economy of the laminate were evaluated. The results are shown in Table 1.

[0057] [Laminate appearance] For the obtained laminate, the laminate appearance was visually confirmed and evaluated according to the following criteria. A: No scratches, defects, unevenness, and good appearance (good) B: Appearance defects such as scratches, defects, and unevenness were observed (not acceptable)

[0058] [Laminate strength] For the obtained laminate, the overlapping part of blue / white and the part where only white was printed were each cut into test pieces with a width of 15 mm and a length of 300 mm. Based on JIS K6854, using an Instron-type tensile testing machine, in an environment of 20 °C and 65% relative humidity, tensile tests were carried out at a peeling speed of 300 mm / min, and the T-peel strength [N / 15 mm] between PET or HDPE and LLDPE was measured. The measurement was performed 5 times, and the average value was taken as the adhesive strength. Evaluation was carried out according to the following criteria based on the obtained adhesive strength and the state of the adhesive after peeling. S: Adhesive strength is 3.0 N / 15 mm or more (very good) A: Adhesive strength is 1.0 N / 15 mm or more and less than 3.0 N / 15 mm, and there is no tack in the adhesive layer (good) B: Adhesive strength is 1.0 N / 15 mm or more and less than 3.0 N / 15 mm, and there is tack in the adhesive layer, or the adhesive strength is less than 1.0 N / 15 mm (not acceptable)

[0059] [Economy, reduction of environmental impact] The adhesive application amount less than the conventional application amount corresponding to Comparative Example 2 was rated as "good", and the amount equal to or more than that was rated as "bad".

[0060]

Table 1

[0061] The abbreviations in Table 1 are shown below. 12μm PET: Biaxially oriented polyester film "FE2001" manufactured by Futamura Chemical Co., Ltd., thickness 12μm 100μm LLDPE: Linear low-density polyethylene film "TUX-FC-D" manufactured by Mitsui Chemicals Toagosei Co., Ltd., thickness 100μm HDPE: Biaxially oriented high-density polyethylene film "MDO PE Film" manufactured by Windmiller Co., thickness 12μm

[0062] According to the results in Table 1, the laminate produced by the manufacturing method of the present invention was excellent in laminate appearance and adhesive strength even when the adhesive application amount was reduced, and it was possible to achieve both economy and reduction of environmental impact. On the other hand, in Comparative Example 1, the laminate appearance deteriorated. This is presumably because the adhesive application amount at the overlapping part of blue / white was less than that at the part where only white was printed, so that the adhesive at the overlapping part of blue / white where the printing layer was thick penetrated more into the printing layer than that at the part where only white was printed, resulting in non-uniform thickness of the adhesive layer on the printing layer. Comparative Example 2 corresponded to Patent Document 1. Since the adhesive application amounts at the overlapping part of blue / white and at the part where only white was printed were the same, it was inferior in economy and reduction of environmental impact. Furthermore, since the solventless adhesive had low cohesive force, the appearance and adhesive strength deteriorated.

Claims

1. A method for manufacturing a laminate having at least a substrate 1, a printed layer having a thickness distribution, an adhesive layer formed from a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent, and a substrate 2 in this order, The printed layer having the thickness distribution is formed from one or more printing inks selected from the group consisting of solvent-based inks, water-based inks, UV-curable inks, two-component curable inks, and toner inks, Step 1 of applying the reactive adhesive on the printed layer of a printed matter comprising at least the substrate 1 and the printed layer having a thickness distribution, and / or on the substrate 2 such that the application amount of the reactive adhesive is larger at the thicker portions of the printed layer than at the thinner portions, Step 2 of bonding the printed layer of the printed matter and the substrate 2 via the adhesive layer formed from the reactive adhesive, A method for manufacturing a laminate having the above steps.

2. The method for manufacturing a laminate according to claim 1, wherein the reactive adhesive is applied by a coating method including at least one selected from the group consisting of an inkjet coating method and a spray coating method.

3. Step a1 of applying the reactive adhesive on the entire surface of the printed layer of a printed matter comprising the substrate 1 and the printed layer having a thickness distribution, and / or on the substrate 2 in step 1, Step a2 of applying the reactive adhesive on the printed layer of a printed matter comprising the substrate 1 and the printed layer having a thickness distribution, and / or on the thicker portions of the printed layer on the substrate 2 in step 1, the method for manufacturing a laminate according to claim 1 or 2 including these steps.

4. The method for manufacturing a laminate according to claim 3, wherein step a1 is performed by a gravure coating method or a spray coating method, and step a2 is performed by an inkjet coating method.

5. The method for manufacturing a laminate according to claim 1 or 2, wherein step 1 includes step b1 of applying the reactive adhesive on the printed layer of a printed matter comprising the substrate 1 and the printed layer having a thickness distribution, and / or on the substrate 2 using an inkjet coating method.

6. An adhesive coating method for applying a reactive adhesive containing a polyol main agent and a polyisocyanate curing agent on the printed layer of a printed matter having at least the substrate 1 and the printed layer having a thickness distribution, The printed layer having the thickness distribution is formed from one or more printing inks selected from the group consisting of solvent-based inks, water-based inks, UV-curable inks, two-component curable inks, and toner inks, An adhesive application method, comprising a step of applying the reactive adhesive such that the application amount of the reactive adhesive is larger at a thick portion of the printing layer than at a thin portion thereof.

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