Laminate, printed matter, water-based dispersion, and method for manufacturing laminate

Abstract

The present application provides a kind of laminate, it is equipped with the release layer that can be formed by water-based coating liquid, quickly from substrate when alkali treatment, and excellent water resistance is excellent.The laminate of the present application is the laminate with release layer on substrate, the release layer includes granular carboxylic anhydride modified olefin resin and the adhesive portion comprising thermoplastic resin without acid group, the average particle size of the carboxylic anhydride modified olefin resin is 0.5-20 μm, the thickness of the adhesive portion is 0.25-20 μm, and the substantial acid value number of the release layer is 100KOHmg / m 2 The above.

Description

Technical Field

[0001] The present invention relates to laminates, printed materials, aqueous dispersions, and methods for manufacturing laminates, and more specifically, to laminates having a release layer on their surface, printed materials having a printing layer on the release layer side surface of the laminate, aqueous dispersions for forming the release layer, and methods for manufacturing the laminates. Background Technology

[0002] Plastics are used in a wide variety of applications, such as containers and packaging bags. Most plastic products are printed on their surfaces for purposes such as conveying information to general consumers and managing product logistics.

[0003] Plastics are partially recycled and reused as secondary products because they are difficult to decompose in nature, conserve resources, and are economical. However, if printed or other plastic products are mixed in during recycling, the recycled products will be colored entirely or partially, thus limiting their use and reducing their reusability.

[0004] Therefore, methods for removing printing ink (de-inking) from printed plastic products have been studied. For example, a release layer that can be detached by alkali treatment is provided on the surface of the plastic, and a printing layer is formed on the surface of the release layer. During product recycling, the printing layer is removed together with the release layer by treatment with an alkaline aqueous solution.

[0005] For example, Patent Document 1 describes a label in which an intermediate layer for removing ink in alkaline hot water exists between an ink layer and a substrate layer on at least one side of a thermoplastic polymer film.

[0006] Patent document 2 describes an article having a removable surface layer formed from a material that becomes water-swellable or water-soluble through neutralization treatment, and describes treatment using an alkaline aqueous solution.

[0007] Patent document 3 describes an alkali-removable label, which is a label having an alkali-removable layer formed on a substrate, and a printing layer applied to the alkali-removable layer or applied through an aluminum vapor deposition layer. The resin composition used in the alkali-removable layer includes random, block and / or graft copolymers and a crosslinking agent component of 0.05 to 15 parts per 100 parts of the copolymer. The random, block and / or graft copolymer contains 20 to 90 wt% of lower alkyl ester units of carboxylic acids having polymerizable unsaturated groups such as acrylic acid, 0.5 to 35 wt% of acid component units such as acrylic acid, and 0.5 to 30 wt% of crosslinkable component units as monomer units.

[0008] Moreover, Patent Document 4 describes a water-based primer composition for forming a release primer layer for a printed material in the order of polyester substrate, release primer layer, and printing layer, wherein (1) it contains a polyurethane resin (A) having carboxyl groups, (2) at least a portion of the carboxyl groups of the polyurethane resin (A) is neutralized by an amine compound (a-1), and (3) the acid value of the polyurethane resin (A) before neutralization is 25 to 45 mg KOH / g.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 11-333952

[0012] Patent Document 2: Japanese Patent Application Publication No. 2001-131484

[0013] Patent Document 3: Japanese Patent Application Publication No. 2002-11819

[0014] Patent Document 4: Japanese Patent Application Publication No. 2017-114930 Summary of the Invention

[0015] The technical problem that the invention aims to solve

[0016] The label described in Patent Document 1 uses a hot alkaline aqueous solution at a temperature above 90°C to remove the ink layer, resulting in low operational efficiency during regeneration. For the article with a releasable surface layer described in Patent Document 2, the treatment solution also needs to be heated to 70°C–80°C, leading to low operational efficiency during regeneration. Furthermore, the coating solution used to form the releasable layer uses ethyl acetate, requiring the disposal of wastewater recovered after removing the printed layer. In the alkaline releasable label described in Patent Document 3, an organic solvent is also used in the coating solution used to form the alkaline releasable layer, failing to consider environmental impact.

[0017] Moreover, the technology in Patent Document 4 uses an aqueous coating liquid as the coating liquid for the release layer. It improves the solubility in water by neutralizing at least a portion of the carboxyl groups of the polyurethane resin (A) contained in the coating liquid. However, the resulting release primer layer does not have sufficient water resistance.

[0018] The present invention was made in view of the above-mentioned problems, and its object is to provide a laminate having a release layer, which can be formed by an aqueous coating liquid, rapidly detaches from the substrate during alkaline treatment, and has excellent water resistance.

[0019] Technical solutions for solving technical problems

[0020] The inventors conducted in-depth research on aqueous coating liquids used to form release layers and obtained the following insights: the release layer formed by an aqueous dispersion obtained by dispersing granular alkali-soluble resin in an aqueous medium can simultaneously improve the release properties from the substrate and enhance water resistance. The inventors then discovered the optimal method for this process, thus completing the present invention.

[0021] The present invention relates to the following (1) to (11).

[0022] (1) A laminate having a release layer on a substrate, the release layer comprising granular carboxylic anhydride-modified olefin resin and an adhesive portion comprising a thermoplastic resin without acid groups, wherein the average particle size of the carboxylic anhydride-modified olefin resin is 0.5–20 μm, the thickness of the adhesive portion is 0.25–20 μm, and the substantial acid number of the release layer is 100 KOH mg / m³. 2 above.

[0023] (2) According to the laminate described in (1) above, wherein the acid value of the carboxylic anhydride modified olefin resin after ring opening by hydrolysis is above 400 KOH mg / g.

[0024] (3) The laminate according to (1) or (2) above, wherein the proportion of the carboxylic anhydride modified olefin resin in the release layer is 5% to 75% by mass.

[0025] (4) The laminate according to any one of (1) to (3) above, wherein the thickness of the adhesive portion is more than 0.1 times the average particle size of the carboxylic anhydride modified olefin resin.

[0026] (5) The laminate according to any one of (1) to (4) above, wherein the substrate comprises a polyolefin resin.

[0027] (6) The laminate according to any one of (1) to (5) above, wherein the thermoplastic resin is a water-soluble polymer or a water-dispersible polymer.

[0028] (7) The laminate according to any one of (1) to (6) above, wherein the laminate is a membrane.

[0029] (8) A printed matter having a printing layer on the release layer of the laminate described in any one of (1) to (7) above.

[0030] (9) An aqueous dispersion for forming a release layer in a printed material having a substrate, a release layer, and a printing layer, wherein the aqueous dispersion contains particulate carboxylic anhydride-modified olefin resin and a thermoplastic resin without acid groups, the average particle size of the carboxylic anhydride-modified olefin resin is 0.5–20 μm, and the actual acid number in the formed release layer is 100 KOH mg / m³. 2 above.

[0031] (10) According to the aqueous dispersion described in (9) above, wherein the acid value of the carboxylic anhydride modified olefin resin after ring opening by hydrolysis is above 400 KOH mg / g.

[0032] (11) A method for manufacturing a laminate, which is a method for manufacturing a laminate having a release layer on a substrate, the method comprising the step of forming the release layer by coating the aqueous dispersion of (9) or (10) onto the substrate and drying it.

[0033] Invention Effects

[0034] According to the present invention, a laminate having a release layer that rapidly detaches from the substrate during alkali treatment and exhibits excellent water resistance can be provided. Furthermore, since the coating solution is an aqueous dispersion, it also offers excellent environmental protection. Attached Figure Description

[0035] Figure 1 This is a cross-sectional view showing the structure of the laminate of the present invention. Detailed Implementation

[0036] The present invention will now be described, but the present invention is not limited to the examples in the following description.

[0037] It should be noted that in this instruction manual, "mass" and "weight" have the same meaning.

[0038] like Figure 1 As shown, the laminate 1 of the present invention has a release layer 5 on a substrate 3. The release layer 5 comprises granular carboxylic anhydride-modified olefin resin 11 and an adhesive portion 12 comprising a thermoplastic resin without acid groups. In the present invention, the average particle size T of the carboxylic anhydride-modified olefin resin 11 is... a The thickness T of the adhesive portion 12 is 0.5–20 μm. b The thickness is 0.25–20 μm, and the actual acid number of the detachment layer 5 is 100 KOH mg / m³. 2 above.

[0039] It should be noted that the composition of the release layer of the laminate of the present invention can be confirmed by observing the cross section of the laminate containing the release layer using a scanning electron microscope.

[0040] (Substrate)

[0041] The substrate 3 that forms the release layer 5 is a component of the article and is not particularly limited; examples include thermoplastic resin molded articles, thermosetting resin molded articles, and non-woven fabrics. Among these, thermoplastic resin molded articles are preferred due to the high demand for reuse.

[0042] The thermoplastic resins constituting thermoplastic molded articles are not particularly limited, and examples include polyolefin resins, polyester resins, polyamide resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl chloride resins, and polycarbonate resins. Examples of polyolefin resins include polyethylene (low-density, medium-density, and high-density), polypropylene, polymethylpentene, polybutene, ethylene-propylene copolymers, and ethylene-vinyl acetate copolymers. One type can be used alone, or two or more can be used in combination.

[0043] From the viewpoint of adhesion to the release layer, polyolefin resin is preferred.

[0044] The shape of the substrate is not particularly limited; examples include film-like or plate-like shapes that are primarily planar, as well as any three-dimensional shape that combines planar and curved surfaces. From an operational point of view, film-like substrates are preferred.

[0045] It should be noted that the film-like substrate can be in roll form or in sheet form.

[0046] In addition, there are no particular restrictions on the size of the substrate.

[0047] For example, when the substrate is a film, from the viewpoint of obtaining good film strength, its thickness is preferably 50 μm or more, more preferably 60 μm or more, and even more preferably 70 μm or more. Furthermore, from the viewpoint of obtaining good flexibility, the thickness of the substrate is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less.

[0048] (Detachment layer)

[0049] The release layer 5, as described above, comprises granular carboxylic anhydride-modified olefin resin 11 and an adhesive portion 12 comprising a thermoplastic resin without acid groups.

[0050] Carboxylic anhydride-modified olefin resin is soluble in alkali. Therefore, by including multiple carboxylic anhydride-modified olefin resins in the release layer, the laminate exhibits water resistance and alkali-removing properties when the laminate is subjected to alkali treatment. Furthermore, by including carboxylic anhydride-modified olefin resins in particulate form in the release layer, the coating liquid used to form the release layer can be used as a water-based substrate. Moreover, by including an adhesive portion containing a thermoplastic resin without acid groups in the release layer, the carboxylic anhydride-modified olefin resin can be retained on the substrate, improving adhesion when a printable layer is applied to the release layer, and also imparting printability to the surface of the release layer.

[0051] Carboxylic anhydride-modified olefin resins refer to compounds having anhydride groups as functional groups. The carboxylic anhydride used in the present invention is preferably one or a mixture of two or more anhydrides selected from the group consisting of anhydrides of α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, with maleic anhydride being particularly preferred. The carboxylic anhydride-modified olefin resin used in the present invention is preferably a copolymer of these anhydrides with one or more mixtures selected from the group consisting of ethylene, propylene, butene, and styrene, with copolymers with isobutylene or styrene being particularly preferred.

[0052] In this invention, the acid value of the carboxylic anhydride-modified olefin resin after ring-opening via hydrolysis is preferably 400 mg / g or higher. If the acid value is 400 mg / g or higher, the release layer will rapidly detach from the substrate during alkali treatment of the laminate.

[0053] The acid value is more preferably 500 KOH mg / g or more, and even more preferably 600 KOH mg / g or more. In addition, when the acid value is too high, the amount of alkali required for alkali treatment increases, so it is preferably 800 KOH mg / g or less.

[0054] Examples of the shapes of granular carboxylic anhydride-modified olefin resins include spherical (perfect spherical, approximately perfect spherical, ellipsoidal, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat, and irregular shapes. Among these, spherical and flat shapes are preferred from the viewpoint of preventing particles from detaching from the release layer and improving ink adhesion.

[0055] The average particle size T of carboxylic anhydride modified olefin resin a The particle size ranges from 0.5 to 20 μm, depending on the size of the carboxylic anhydride-modified olefin resin in the raw material. If the average particle size T... a If the particle size is 0.5 μm or larger, it exhibits sufficient alkali detachment and can suppress the viscosity increase of the coating solution during the formation of the detachment layer, thus providing good operability. Furthermore, if the average particle size T... aIf the surface area is below 20 μm, the specific surface area of ​​the carboxylic anhydride-modified olefin resin in the release layer can be increased, thus improving the alkali release property.

[0056] The average particle size T of carboxylic anhydride modified olefin resin a Preferably, the micrometer is 1 μm or more, more preferably 2 μm or more, and preferably 15 μm or less, more preferably 10 μm or less.

[0057] The proportion of carboxylic anhydride-modified olefin resin in the release layer can be appropriately adjusted according to the acid value of the carboxylic anhydride-modified olefin resin after ring-opening through hydrolysis, so that the actual acid value is within the range of the present invention, preferably 5% to 75% by mass. If the proportion of carboxylic anhydride-modified olefin resin is 5% by mass or more, alkali release is easily exhibited; if it is 75% by mass or less, the adhesion between the release layer and the substrate is easily maintained.

[0058] In the release layer, the carboxylic anhydride modified olefin resin more preferably contains 20% or more by mass, more preferably 40% or more by mass, and even more preferably 70% or less by mass, more preferably 65% ​​or less by mass.

[0059] The adhesive layer serves to hold the carboxylic anhydride-modified olefin resin on the substrate and to capture inks and toners printed on the surface of the laminate. The adhesive layer contains at least a thermoplastic resin without acid groups as the binder resin.

[0060] Thermoplastic resins without acid groups can be used without particular restriction as long as they do not contain acid groups; water-soluble polymers or water-dispersible polymers are preferred. Water-soluble polymers or water-dispersible polymers are preferably cationic. Cationic water-dispersible polymers are more preferred. It should be noted that in this specification, cationic water-soluble polymers or cationic water-dispersible polymers are sometimes described as cationic water-soluble polymers or water-dispersible polymers. Due to the polar groups possessed by cationic water-soluble polymers or water-dispersible polymers, the adhesive portion can chemically bond (specifically, using ionic bonding) and dispersedly bond (specifically, using van der Waals forces) to the ink or toner. It can be inferred that the transferability and adhesion of the ink or toner relative to the release layer are improved.

[0061] It should be noted that the water solubility of a cationic water-soluble polymer is sufficient to mean that the aqueous medium containing the cationic water-soluble polymer is in a solution state when the coating liquid forming the release layer is prepared.

[0062] Examples of usable cationic water-soluble or water-dispersible polymers include (meth)acrylic acid polymers with amino or ammonium salt structures, urethane polymers, ethylene imine polymers, water-soluble polymers with phosphonium salt structures, and vinyl polymers that are cationized by modifying water-soluble polymers such as polyvinylpyrrolidone and polyvinyl alcohol. One of these polymers may be used alone or in combination of two or more.

[0063] From the viewpoint of the release layer's detachability during alkali treatment of the laminate, urethane-based polymers are preferred. Furthermore, from the viewpoint of the transferability and adhesion of the release layer to ink or toner, (meth)acrylic polymers or ethyleneimine polymers having amino or ammonium salt structures are preferred.

[0064] Examples of urethane polymers include cationic modified urethane resins, cationic ether urethane resins, cationic carbonate urethane resins, cationic ester urethane resins, or other cationic urethane resins. From the viewpoint of excellent release properties of the release layer, cationic ester urethane resins are preferred.

[0065] As a urethane polymer, commercially available products can also be used.

[0066] Commercially available products that are urethane polymers include Daiichi Kogyo Pharmaceutical Co., Ltd.’s “SUPERFLEX” series, Taisei Fine Chemical Co., Ltd.’s “WBR” series, and “WEM” series.

[0067] From the viewpoint of improving detachability during alkali treatment, the glass transition temperature (Tg) of the urethane polymer is preferably -30°C or higher, more preferably -10°C or higher. On the other hand, from the viewpoint of good adhesion to the substrate, the glass transition temperature (Tg) is preferably 60°C or lower, more preferably 45°C or lower.

[0068] From a safety perspective, (meth)acrylic polymers or ethylene imine polymers having an amino or ammonium salt structure preferably have a primary to tertiary amino or ammonium salt structure, more preferably a secondary to tertiary amino or ammonium salt structure, and even more preferably a tertiary amino or ammonium salt structure.

[0069] Among them, ethylene imine polymers are used with inks or toners in various printing methods.

[0070] In particular, UV-curable inks used in flexographic printing have high affinity, thus improving the adhesion between the release layer and the ink, making them a preferred choice.

[0071] Examples of ethyleneimine polymers include polyethyleneimine, poly(ethyleneimine-urea), ethyleneimine adducts of polyamine polyamides, their alkyl-modified, cycloalkyl-modified, aryl-modified, allyl-modified, aralkyl-modified, benzyl-modified, cyclopentyl-modified, cyclic aliphatic hydrocarbon-modified, glycidyl-modified, and their hydroxides. Examples of modifiers used to obtain the modified products include methyl chloride, methyl bromide, n-butyl chloride, lauryl chloride, stearyl iodide, oleoyl chloride, cyclohexyl chloride, benzyl chloride, allyl chloride, and cyclopentyl chloride.

[0072] From the viewpoint of improving the transferability and adhesion of inks or toners used in printing, especially UV-curable inks, ethylene imine polymers represented by the following general formula (I) are preferred.

[0073] [Chemistry 1]

[0074]

[0075] In the above formula (I), R 1 and R 2 Each can independently represent a hydrogen atom; a straight-chain or branched alkyl group having 1 to 12 carbon atoms; or an alkyl or aryl group having an alicyclic structure having 6 to 12 carbon atoms. R 3 [This refers to a hydrogen atom; an alkyl or allyl group containing a hydroxyl group and having 1 to 18 carbon atoms; or an alkyl or aryl group containing a hydroxyl group and having 6 to 12 carbon atoms with an alicyclic structure. m represents an integer from 2 to 6, and n represents an integer from 20 to 3000.]

[0076] Commercially available products can also be used as (meth)acrylic polymers or ethylene imine polymers having an amino or ammonium salt structure.

[0077] Commercially available products that are (meth)acrylic acid polymers with amino or ammonium salt structures include "POLYMENT" manufactured by Nippon Shokubai Co., Ltd.

[0078] In addition, commercially available products of ethylene imine polymers include "EPOMIN" manufactured by Nippon Shokubai Co., Ltd., and "POLYMIN SK" manufactured by BASF Co., Ltd.

[0079] From the viewpoint of improving adhesion to substrates and inks, the lower limit of the weight-average molecular weight of (meth)acrylic polymers or ethylene imine polymers having amino or ammonium salt structures is preferably 10,000, more preferably 20,000. On the other hand, the upper limit of the weight-average molecular weight is preferably 1,000,000, more preferably 500,000.

[0080] For non-acid-group thermoplastic resins to function as adhesives, they need to possess appropriate adhesive properties. If the glass transition temperature (Tg) of the non-acid-group thermoplastic resin is too low, the surface of the laminate becomes sticky, easily leading to the adhesion and clumping of overlapping laminates. Therefore, a glass transition temperature (Tg) of -30°C or higher is preferred. Conversely, if the glass transition temperature (Tg) of the non-acid-group thermoplastic resin is too high, it becomes too rigid, sometimes reducing its adhesion to substrates, carboxylic anhydride-modified olefin resins, inks, etc. Therefore, a glass transition temperature (Tg) of 80°C or lower is preferred.

[0081] In order to perform well as an adhesive, the glass transition temperature (Tg) of the thermoplastic resin without acid groups is more preferably -10°C or higher, and even more preferably 60°C or lower, and further preferably 45°C or lower.

[0082] In the adhesive layer, the thermoplastic resin without acid groups preferably comprises 60% by mass or more. If the content of the thermoplastic resin without acid groups in the adhesive layer is 60% by mass or more, the adhesion of the ink / toner to the release layer is improved. The content of the thermoplastic resin without acid groups in the adhesive layer is more preferably 65% ​​by mass or more, further preferably 70% by mass or more, and there is no particular upper limit; it can be 100% by mass, but it is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less.

[0083] Without impairing the effects of the invention, the adhesive portion may contain components other than thermoplastic resins without acid groups.

[0084] Other components include, for example, silane coupling agents, antistatic agents, crosslinking accelerators, antiblocking agents, pH adjusters, defoamers, dispersants, wetting agents, emulsifiers, thickeners, antisettling agents, anti-sagging agents, leveling agents, desiccants, plasticizers, rust inhibitors, antibacterial agents, insecticides, preservatives, light stabilizers, ultraviolet absorbers, and conductivity imparting agents.

[0085] In the release layer, the proportion of the adhesive portion is preferably 25% to 95% by mass. If the proportion of the adhesive portion is 25% by mass or more, the carboxylic anhydride-modified olefin resin can be prevented from detaching from the substrate, and if it is 95% by mass or less, the alkali release property based on the carboxylic anhydride-modified olefin resin will not be hindered.

[0086] In the release layer, the adhesive portion more preferably contains 30% by mass or more, more preferably 35% by mass or more, and even more preferably 80% by mass or less, more preferably 60% by mass or less.

[0087] In the laminate of the present invention, the thickness T of the adhesive portion bThe thickness is 0.25–20 μm. If the thickness T of the bonded portion… b If the thickness is above 0.25 μm, it is easy to prevent granular carboxylic anhydride modified olefin resin from falling off the release layer; if it is below 20 μm, it can improve productivity and suppress cost increases.

[0088] Thickness T of the bonded part b More preferably, it is 0.5 μm or more, even more preferably 1 μm or more, and even more preferably 15 μm or less, and even more preferably 10 μm or less.

[0089] It should be noted that the thickness T of the bonded portion b The average particle size T of granular carboxylic anhydride modified olefin resin a (T b / T a Preferably, it is 0.1 times or more. If the thickness T of the bonded portion... b The average particle size T of the carboxylic anhydride modified olefin resin a If the concentration is more than 0.1 times that of the substrate, the retention of the carboxylic anhydride-modified olefin resin on the substrate will be improved.

[0090] Thickness T of the bonded part b The average particle size T of granular carboxylic anhydride modified olefin resin a (T b / T a More preferably, it is 0.2 times or more, even more preferably 0.5 times or more. In addition, from the viewpoint of the alkali solubility of the release layer, it is preferably 3 times or less, even more preferably 2 times or less. Furthermore, when the particles of carboxylic anhydride modified olefin resin are present near the surface of the adhesive portion, the alkali solubility of the release layer becomes better, so it is even more preferably 1.2 times or less.

[0091] The preferred detachment layer of the laminate of the present invention has a substantial acid value of 100 KOH mg / m³. 2 above.

[0092] "Actual acid value" refers to the acid value per unit area of ​​the release layer, calculated from the actual amount of carboxylic anhydride-modified olefin resin contained in the release layer and the acid value of the carboxylic anhydride-modified olefin resin.

[0093] Set the basis weight of the separation layer to X (g / m³). 2 When the content of carboxylic anhydride-modified olefin resin in the release layer is set as Y (mass %) and the acid value of the carboxylic anhydride-modified olefin resin after ring opening by hydrolysis is set as Z (KOH mg / g), the actual acid value of the release layer is expressed by the following formula.

[0094] Actual acid value (KOH mg / m) 2 )=X×0.01Y×Z

[0095] It should be noted that the acid value of carboxylic anhydride modified olefin resin after ring-opening through hydrolysis can be determined by neutralization titration in JIS K 0070-1992 "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products".

[0096] The higher the actual acid number of the release layer, the better the alkali release ability, but the acid number is less than 100 KOH mg / m³. 2 At this point, it becomes difficult to achieve the desired effect of the present invention, therefore 100 KOH mg / m³ is preferred. 2 The above. A more preferable actual acid value is 400 KOH mg / m³. 2 That's all. Additionally, there's no specific upper limit, but if the actual acid number is too high, the amount of alkali required for alkali removal treatment increases. Therefore, the preferred actual acid number is 3000 KOH mg / m³. 2 The following is more preferably 2000 KOH mg / m³ 2 The following is a further preferred value: 1500 KOH mg / m³ 2 the following.

[0097] The shape of the laminate of the present invention is based on the shape of the substrate and is not particularly limited. For example, it can be a film-like or plate-like shape with a planar main body, or an arbitrary three-dimensional shape composed of a combination of planar and curved surfaces.

[0098] From the perspective of ease of operation and formability, a film-like form is preferred.

[0099] (Manufacturing method of laminated bodies)

[0100] The method for manufacturing the laminate of the present invention includes a step of forming a release layer by coating an aqueous dispersion for forming a release layer onto a substrate and drying it.

[0101] The aqueous dispersion used in the manufacture of the laminate contains granular carboxylic anhydride-modified olefin resin and a thermoplastic resin without acid groups. It can be prepared by dissolving or dispersing the carboxylic anhydride-modified olefin resin and the thermoplastic resin without acid groups, as well as any other components as needed, in an aqueous solvent.

[0102] Aqueous solvents can be water, or they can be water-based with water as the main component and contain water-soluble organic solvents such as methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, toluene, and xylene. Water as the main component means that the total content is 50% or more by mass. Using aqueous solvents simplifies process management and is preferred from a safety perspective.

[0103] Carboxylic anhydride-modified olefin resin, thermoplastic resin without acid groups, and any other components are as described above, and the preferred components are also the same.

[0104] In the solid component of the aqueous dispersion, the content of carboxylic anhydride-modified olefin resin is preferably 5% to 75% by mass. If the content of carboxylic anhydride-modified olefin resin is within the above range, both alkali detachment and binding properties can be achieved.

[0105] In the solid component of the aqueous dispersion, the carboxylic anhydride modified olefin resin more preferably contains 20% or more by mass, more preferably 40% or more by mass, and even more preferably 70% or less by mass, more preferably 65% ​​or less by mass.

[0106] In addition, the content of thermoplastic resin without acid groups in the solid component of the aqueous dispersion can be adjusted so that the content of carboxylic anhydride modified olefin resin is within the above-mentioned range.

[0107] It should be noted that, in the formation of the release layer, the aqueous dispersion of the present invention achieves a substantial acid value of 100 KOH mg / m³. 2 above.

[0108] To achieve the actual acid value within the aforementioned range, one could adjust the content of the carboxylic anhydride-modified olefin resin or adjust the acid value of the carboxylic anhydride-modified olefin resin after ring-opening via hydrolysis.

[0109] When the solid content concentration of the aqueous dispersion is 20% by mass, the viscosity at 20°C is preferably 5–200 mPa·s. If the viscosity is too low, the dispersion in the aqueous dispersion is prone to precipitation and agglomeration, sometimes resulting in uneven coating during the application of the release layer. Conversely, if the viscosity is too high, it may be difficult to achieve a stable low coating amount.

[0110] The viscosity of the aqueous dispersion is more preferably 15 mPa·s or more, even more preferably 20 mPa·s or more, and even more preferably 150 mPa·s or less, and even more preferably 120 mPa·s or less.

[0111] It should be noted that the viscosity was measured using a Type B viscometer at a rotation speed of 60 rpm.

[0112] The coating of aqueous dispersions and the drying of the coating film can be carried out online in conjunction with the molding of the substrate, or offline.

[0113] Aqueous dispersions can be coated using various coating devices, including die coaters, bar coaters, roller coaters, lip coaters, gravure coaters, spray coaters, scraper coaters, reverse coaters, and air knife coaters.

[0114] The coating amount of the aqueous dispersion can be adjusted appropriately by taking into account the thickness of the release layer after drying and the concentration of the components.

[0115] The coated film can be dried using drying equipment such as a hot air blower or an infrared dryer. Drying can be carried out at room temperature or by heating. When heating, it is preferable to carry out the drying at 40°C to 200°C, and more preferably at 60°C to 150°C.

[0116] By drying the coated film, a thermoplastic resin without acid groups is melted to form a film, thereby forming a release layer on the substrate that retains the carboxylic anhydride-modified olefin resin.

[0117] (Printed materials)

[0118] The printed material of the present invention has a printing layer on the release layer of the laminate of the present invention, and is obtained by forming the printing layer on the release layer.

[0119] The printed layer is a layer composed of text, images, etc., formed by printing ink or toner.

[0120] The printed layer is located on the surface of the release layer side of the laminate of the present invention, and can cover at least a portion of the release layer surface, or it can cover the entire area.

[0121] As a printing method, various printing methods can be used, such as offset printing, inkjet printing, electrophotography (laser), thermal recording, and thermal transfer. Various coating devices, such as the mold coating machine and the bar coating machine mentioned above, can also be used.

[0122] (Methods for removing the printed layer)

[0123] In order to separate (remove) the release layer and the printing layer from the printed material, the printed material is brought into contact with an alkaline aqueous solution.

[0124] Examples of alkaline aqueous solutions include sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia water, barium hydroxide, and calcium hydroxide.

[0125] The concentration of the alkaline aqueous solution can be adjusted appropriately according to the printing method and processing time of the printed material. It is preferred to use it in the range of 0.5% to 15% by mass, and more preferably 1% to 5% by mass.

[0126] By keeping the concentration of the alkaline aqueous solution within the above range, the alkaline aqueous solution can maintain sufficient alkalinity for detachment and is also suitable for penetrating from the cross-section of the printed material and laminate to dissolve with the release layer, thus enabling ink detachment in a shorter time.

[0127] Furthermore, from the perspective of environmental protection and wastewater treatment in the recycling process, it is even more preferable that the concentration of the alkaline solution is below 5%.

[0128] The amount of alkaline aqueous solution used is preferably 100 to 1,000,000 times the mass of the printed material or laminate. If the amount of alkaline aqueous solution used is more than 100 times the mass of the printed material or laminate, the alkaline release effect of the release layer can be fully obtained. In addition, even if the amount of alkaline aqueous solution used is too large, the release effect does not change. Therefore, it is preferable to use less than 1,000,000 times the mass.

[0129] The amount of alkaline aqueous solution used relative to the mass of the printed material or laminate is more preferably 200 times or more, more preferably 300 times or more, and even more preferably 10,000 times or less, and even more preferably 5,000 times or less.

[0130] The temperature of the alkaline aqueous solution used in the treatment is preferably room temperature to 90°C, specifically preferably 20°C or higher, more preferably 30°C or higher, and from the viewpoint of treatment efficiency, more preferably 70°C or lower, even more preferably 65°C or lower, and particularly preferably 60°C or lower.

[0131] There are no particular limitations on the method of contacting the alkaline aqueous solution with the printed material or laminate, but from the viewpoint of efficiency in alkali removal treatment, immersion in the alkaline aqueous solution is preferred. By immersing in the alkaline aqueous solution, the printed material or laminate comes into contact with the alkaline aqueous solution as a whole, thus enabling highly efficient treatment.

[0132] The immersion time can be adjusted appropriately according to the printing method of the printed material, preferably from 1 minute to 24 hours, and more preferably from 1 minute to 12 hours.

[0133] Specifically, when the printed material is surface printed, the concentration of the alkaline aqueous solution is preferably 0.5 to 15% by mass, the immersion temperature is preferably 30°C to 70°C, and the immersion time is preferably 1 to 12 hours.

[0134] When the printed material is back-side printed (laminated), the concentration of the alkaline aqueous solution is preferably 1 to 15% by mass, the immersion temperature is preferably 30 to 70°C, and the immersion time is preferably 1 to 12 hours.

[0135] After alkali treatment, the product is washed with water and dried to obtain an item with the printed matter removed (de-inking).

[0136] In this invention, the removal rate of the printed layer is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0137] It should be noted that, in order to improve efficiency, when removing the printed layer from the printed material, cyclic rinsing, crushing, and agitation of the printed material or laminate can be performed.

[0138] By using the laminate of the present invention, printed materials having a printing layer on the surface of the laminate (detached layer side surface) can have the printing layer removed in an alkaline aqueous solution, followed by washing and drying to obtain a recycled substrate. Furthermore, when the recycled substrate is a thermoplastic resin, it can be recycled into granules using an extruder for utilization.

[0139] Example

[0140] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments. It should be noted that unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass," respectively.

[0141] <Evaluation Methods>

[0142] The following shows the evaluation of the laminates obtained in the following embodiments and comparative examples.

[0143] 1. Calculation of the actual acid number of the delamination layer

[0144] The acid value of the carboxylic anhydride modified olefin resin in the release layer was determined by neutralization titration according to JIS K 0070-1992 "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products". The actual acid value (acid value per unit area in the release layer) was calculated based on the following formula.

[0145] Actual acid value (KOH mg / m) 2 )=X×0.01Y×Z

[0146] (In the above formula, X is the basis weight of the detachment layer (g / m³)) 2 Y represents the content (mass%) of carboxylic anhydride-modified olefin resin in the release layer, and Z represents the acid value (KOH mg / g) of the carboxylic anhydride-modified olefin resin.

[0147] 2. Film thickness at the bonding area

[0148] The cross-section of the laminate was observed at 5000x magnification using a scanning electron microscope, and the film thickness of the adhesive portion was determined from the obtained images.

[0149] 3. Surface roughness SRa

[0150] The average surface roughness (SRa) of the center surface of the laminate was determined using a SURFCOM 1500DX2 contact surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd., in accordance with JISB0601-1982. It should be noted that the settings were: cutoff 0.8 mm, measurement length 5 mm, scanning interval 20 μm, and number of scans 30.

[0151] 4. Deinking property (alkali stripping property)

[0152] The laminates obtained in each embodiment and comparative example were cut into A2 sheets (420mm × 594mm), and a pattern including designs was printed on the surface of the release layer using offset printing. Printing was performed using an offset printing press (trade name: SM102, manufactured by Heidelberg) and oxidative polymeric sheet-fed three-color inks (trade name: Fusion G (black, blue, magenta, yellow), manufactured by DIC). The pattern was printed using four colors: black, blue, magenta, and yellow, each with a 100% concentration. Specifically, offset prints were obtained by continuously printing 1000 sheets at a speed of 8000 sheets / hour at an environment of 23°C and 50% relative humidity.

[0153] The following evaluations were conducted using the obtained printed materials.

[0154] Fifty printed sheets, each 5mm long and 5mm wide, were immersed in 100g of a 2% alkaline aqueous solution (sodium hydroxide) at a water temperature of 20°C or 40°C.

[0155] Using a BLW1200 mixer manufactured by Shin-To Science Co., Ltd., start mixing at 1000 rpm and mix for 20 minutes.

[0156] After stirring, the sample was washed with water and dried. The surface was observed using a Hirox HRX-01 digital microscope to measure the area of ​​the removed portion of the printed layer, calculate the removal rate, and evaluate it according to the following evaluation criteria.

[0157] [Evaluation Criteria]

[0158] A (Good): Removal rate above 95%

[0159] B (Qualified): Removal rate above 70% but less than 95%

[0160] C (Unacceptable): Removal rate less than 70%

[0161] 5. Water resistance

[0162] After immersing the printed material obtained in item “4. Deinking property (alkali peeling property)” in water at 23°C for 24 hours, remove it and gently wipe the moisture off the printed surface with a cloth. After 10 minutes, stick a 5cm length of transparent tape made by Nichiban Corporation onto the printed surface, peel off 2.5cm by hand at a low speed (2.5cm / s) and the remaining 2.5cm at a high speed (25cm / s).

[0163] Visually confirm the degree of peeling of the printed portion after removal. Evaluate the ink adhesion in the wet state according to the following evaluation criteria. It should be noted that a score of 3 or higher is considered acceptable, and a score below 2 is considered unacceptable.

[0164] [Evaluation Criteria]

[0165] 5: No peeling at both low and high speeds.

[0166] 4: No peeling at low speed, partial peeling (less than 50% of the entire high-speed peeling surface) at high speed.

[0167] 3: No peeling at low speed, but peeling of the entire surface (more than 50% of the entire surface) at high speed.

[0168] 2: Low-speed partial peeling (less than 50% of the entire low-speed peeling surface), high-speed full-surface peeling (more than 50% of the entire high-speed peeling surface).

[0169] 1: Peeling is performed evenly on both low and high speeds.

[0170] <Raw Materials Used>

[0171] The raw materials used in the examples and comparative examples are described below.

[0172] (Carboxylic anhydride modified olefin resin)

[0173] • Isobutylene-maleic anhydride copolymer (Kuraray Co., Ltd. "Isobam-04" (trade name), molecular weight 55,000-65,000, acid value 728 KOH mg / g)

[0174] • Styrene-maleic anhydride copolymer (Polyscope "XIRAN 1000P" (trade name), molecular weight 5000, styrene:maleic anhydride copolymer ratio = 1:1, acid value 475 KOH mg / g)

[0175] (Thermoplastic resin)

[0176] • Cationic modified polyurethane resin (Daiichi Kogyo Pharmaceutical Co., Ltd. "SUPERFLEX 620" (trade name), non-yellowing isocyanate type)

[0177] <Manufacturing Example 1: Substrate Manufacturing>

[0178] (I) Prepare resin composition a by mixing 55% by mass of propylene homopolymer (trade name: NOVATEC PP FY6Q, manufactured by Japan Polypropylene Co., Ltd.), 12% by mass of propylene homopolymer (trade name: NOVATEC PP MA3Q, manufactured by Japan Polypropylene Co., Ltd.), 10% by mass of high-density polyethylene resin (trade name: NOVATEC HD HJ580N, manufactured by Japan Polypropylene Co., Ltd.), and 23% by mass of heavy calcium carbonate granules (trade name: Softon 1800, manufactured by Bikhoku Powder Chemical Industry Co., Ltd.).

[0179] (II) Next, resin composition a is melt-blended using an extruder set to 270°C and extruded into a sheet from a die. The sheet is cooled using cooling rollers to obtain an unstretched sheet. The unstretched sheet is then reheated to 150°C and stretched 4.8 times along the sheet travel direction (MD) using the speed difference between the rollers to obtain a longitudinally uniaxially stretched resin film.

[0180] (III) In addition, resin composition b was prepared by mixing 47% by weight of a mixed propylene homopolymer (trade name: NOVATEC PP MA3Q, manufactured by Japan Polypropylene Co., Ltd.) and 53% by weight of light calcium carbonate particles (trade name: Calfine YM23, Maruo Calcium).

[0181] The film is melt-blended using an extruder set to 250°C, and extruded into a film shape on one side of the longitudinal uniaxial stretch film by a die, and then laminated to obtain a laminate of the first surface layer / core layer (b / a).

[0182] Then, using another extruder, the above-mentioned resin composition b is melt-blended using an extruder set to 250°C, and extruded into a film through a die, which is then laminated onto the core layer (a) side of the above-mentioned laminate (b / a). Thus, a laminate (b / a / b) with a three-layer structure of first surface layer / core layer / second surface layer is obtained.

[0183] The three-layer laminate was introduced into a tenter furnace and heated to 150°C. Then, it was stretched 8 times in the transverse direction using a tenter frame. Next, it was heat-set (annealed) at 165°C and further cooled to 60°C. The edges were then cut to obtain a thermoplastic resin film with a thickness of 110 μm as the substrate (1).

[0184] <Experimental Example>

[0185] (Example 1)

[0186] Isobam-04 (trade name) manufactured by Kurara Co., Ltd. was used as the isobutylene-maleic anhydride copolymer. It was pulverized using a bead mill to obtain flat particles with an average particle size (D50) of 3.6 μm.

[0187] A dispersion was prepared by mixing 100 parts of pulverized isobutylene maleic anhydride copolymer particles with 20 parts of cationic modified polyurethane resin (Daichi Kogyo Pharmaceutical Co., Ltd. "SUPERFLEX 620" (trade name)) and water at a solid content concentration of 20% by mass, and stirring at 20°C and 500 rpm for 10 minutes.

[0188] Next, on the surface of the substrate (1) obtained in Manufacturing Example 1, a bar coater was used to apply a coating of 2.0 g / m² after drying.2 The dispersion was applied in a manner that the thickness of the bonding layer was 2.0 μm.

[0189] Then, dry at 70°C for 2 minutes to obtain a laminate with a release layer.

[0190] (Example 2)

[0191] Except for using 150 parts of cationic modified polyurethane resin, a dispersion was prepared in the same manner as in Example 1, and a laminate was prepared using the obtained dispersion.

[0192] (Example 3)

[0193] Except for using 900 parts of cationic modified polyurethane resin, a dispersion was prepared in the same manner as in Example 1, and a laminate was prepared using the obtained dispersion.

[0194] (Example 4)

[0195] By changing the pulverization conditions of "Isobam-04" (trade name) manufactured by Kuraray Co., Ltd., which is an isobutylene maleic anhydride copolymer, plate-shaped particles with an average particle size (D50) of 13.8 μm were prepared. Otherwise, a dispersion was prepared in the same manner as in Example 1, and a laminate was prepared using the obtained dispersion.

[0196] (Example 5)

[0197] Except for using 150 parts of cationic modified polyurethane resin, a dispersion was prepared in the same manner as in Example 4, and a laminate was prepared using the obtained dispersion.

[0198] (Example 6)

[0199] Except for using 900 parts of cationic modified polyurethane resin, a dispersion was prepared in the same manner as in Example 4, and a laminate was prepared using the obtained dispersion.

[0200] (Example 7)

[0201] The dispersion was prepared in the same manner as in Example 1, except that a styrene-maleic anhydride copolymer (Polyscope's "XIRAN 1000P" (trade name)) was used instead of an isobutylene-maleic anhydride copolymer, and the resulting dispersion was used to prepare a laminate.

[0202] (Example 8)

[0203] Except for using 150 parts of cationic modified polyurethane resin, a dispersion was prepared in the same manner as in Example 7, and a laminate was prepared using the obtained dispersion.

[0204] (Comparative Example 1)

[0205] Except for using 900 parts of cationic modified polyurethane resin, a dispersion was prepared in the same manner as in Example 7, and a laminate was prepared using the obtained dispersion.

[0206] (Comparative Example 2)

[0207] Instead of using cationic modified polyurethane resin, the substance obtained by neutralizing isobutylene maleic anhydride copolymer with ammonia is dissolved in water and used. Otherwise, the laminate is prepared in the same manner as in Example 1.

[0208] For the laminates of Examples 1-8 and Comparative Examples 1-2, the proportion of carboxylic anhydride-modified olefin resin in the release layer, the actual acid number, the film thickness of the adhesive portion, and the surface roughness SRa were measured, and the deinking performance was evaluated. The results are shown in Table 1.

[0209] [Table 1]

[0210]

[0211] As shown in Table 1, Examples 1-8 all achieved a print layer removal rate of over 95% after alkali treatment at 40°C for 20 minutes, and a removal rate of over 70% after alkali treatment at 20°C for 20 minutes, demonstrating excellent detachment properties. In contrast, Comparative Example 1 achieved a removal rate of over 70% after alkali treatment at 40°C for 20 minutes, but the removal was insufficient after alkali treatment at 20°C for 20 minutes.

[0212] Furthermore, it can be seen that although Comparative Example 2 has good detachability based on alkali treatment, the water resistance of the detachment layer is insufficient, while Examples 1 to 8 can improve water resistance.

[0213] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2021-061176, filed on March 31, 2021, the contents of which are incorporated herein by reference.

[0214] Explanation of reference numerals in the attached figures

[0215] 1. Layered body

[0216] 3. Substrate

[0217] 5 Detachment layer

[0218] 11 Carboxylic anhydride modified olefin resin

[0219] 12 Adhesive section

[0220] T a Average particle size of carboxylic anhydride modified olefin resin

[0221] T b Thickness of the bonded part

Claims

1. A laminated body, characterized in that, For a laminate having a release layer on a substrate, The release layer comprises granular carboxylic anhydride-modified olefin resin and an adhesive portion containing a thermoplastic resin without acid groups. The average particle size of the carboxylic anhydride-modified olefin resin is 0.5–20 μm, the thickness of the adhesive portion is 0.25–20 μm, and the actual acid value of the release layer is 100 KOH mg / m³. 2 above.

2. The laminated body according to claim 1, wherein, The acid value of the carboxylic anhydride-modified olefin resin after ring-opening via hydrolysis is above 400 KOH mg / g.

3. The laminate according to claim 1 or 2, wherein, The proportion of the carboxylic anhydride-modified olefin resin in the release layer is 5% to 75% by mass.

4. The laminate according to any one of claims 1 to 3, wherein, The thickness of the adhesive portion is more than 0.1 times the average particle size of the carboxylic anhydride-modified olefin resin.

5. The laminate according to any one of claims 1 to 4, wherein, The substrate comprises a polyolefin resin.

6. The laminate according to any one of claims 1 to 5, wherein, The thermoplastic resin is a water-soluble polymer or a water-dispersible polymer.

7. The laminate according to any one of claims 1 to 6, wherein, The laminate is membrane-like.

8. A printed material, characterized in that, The release layer of the laminate according to any one of claims 1 to 7 has a printed layer.

9. An aqueous dispersion, characterized in that, An aqueous dispersion for forming the release layer in a printed material having a substrate, a release layer, and a printing layer. The aqueous dispersion contains granular carboxylic anhydride-modified olefin resin and thermoplastic resin without acid groups. The average particle size of the carboxylic anhydride-modified olefin resin is 0.5–20 μm, and The actual acid value of the detached layer is 100 mg / m³. 2 above.

10. The aqueous dispersion according to claim 9, wherein, The acid value of the carboxylic anhydride-modified olefin resin after ring-opening via hydrolysis is above 400 KOH mg / g.

11. A method for manufacturing a laminated body, characterized in that, This is a method for manufacturing a laminate with a release layer on a substrate. The method for manufacturing the laminate includes the step of forming the release layer by coating the aqueous dispersion of claim 9 or 10 onto the substrate and drying it.

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