Laminate and packaging body using the same

Abstract

The present application is a kind of laminate, sequentially laminated with base material, release layer and heat seal layer, base material is selected from paper or non-woven fabric, release layer is (meth) acrylate homopolymer or copolymer coating film, containing microparticles in a proportion of 25 mass% or less relative to the total amount of the coating film, heat seal layer is olefin-alpha, beta unsaturated carboxylic acid copolymer coating film. According to the present application, a laminate with excellent clean release and heat seal layer and a package using the laminate can be provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a laminate and a packaging body using the laminate. BACKGROUND

[0002] In a medical site or the like, a syringe, a surgical glove or the like medical instrument used is an instrument enclosed inside a packaging body in a sterilized state. As a sterilization method, after a medical instrument or the like as a sterilization target is enclosed in a packaging body, gas sterilization using ethylene oxide gas (EOG) or the like, irradiation sterilization using γ-rays or the like is performed, and since the gas needs to permeate, the packaging body for EOG sterilization is configured by overlapping a nonwoven fabric or paper and a plastic film and heat-sealing the peripheral edge portions. Such a packaging body for sterilization requires, in addition to the heat-sealing strength of the nonwoven fabric or paper and the plastic substrate, of course, gas permeability and easy openability at the time of taking out the enclosed article, and a resin such as ethylene-vinyl acetate copolymer has been used as a heat-sealant in the past (see Patent Document 1).

[0003] Further, as a characteristic necessary for a medical packaging body, it is important that the peelability at the time of taking out the enclosed article such as a medical instrument at the time of use is good, that is, there is no fiber drop from the paper or the nonwoven fabric at the time of opening, and the paper or the nonwoven fabric can be peeled cleanly (clean peelability). Thus, a method of preventing fiber drop by providing a peel layer and a heat-seal layer at the paper or the nonwoven fabric and peeling at the interface of the peel layer and the heat-seal layer is known (see Patent Document 2).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 63-216571

[0007] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2000-107268 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, if fiber drop at the time of opening is to be prevented, the heat-sealing strength, which is a basic characteristic of the packaging body, is impaired. On the other hand, if the heat-sealing strength is to be maintained, sufficient clean peelability cannot be obtained. As described above, since the clean peelability and the heat-sealing strength are in a trade-off relationship, it is difficult to achieve both of them.

[0010] For example, in order to prevent the peeling of the heat-seal layer while maintaining the adhesiveness, there is a method of increasing the thickness of the heat-seal layer to cope with the peeling. However, in this method, the control of the heat-seal strength is difficult, and in addition, an apparatus for thickly applying the heat-seal agent is required, and the production is not easy. In addition, since the conventional heat-seal agent uses a volatile organic solvent (VOC), if the thickness of the heat-seal layer is increased, the amount of the VOC discharged also increases, and there are problems of the deterioration of the atmospheric pollution by the VOC, global warming, and the like. From the viewpoint of sustainability in the background of the expansion of these environmental pollutions, it is desired to change to a water-based solvent in which the organic solvent is replaced by water on a world scale.

[0011] On the other hand, the method described in Patent Literature 2 uses a water dispersion liquid containing a pigment in the peeling layer coating material, but since a large amount of the pigment is contained in the peeling layer, the solid content viscosity is reduced when the dispersion liquid is adjusted to an appropriate viscosity at the time of printing, and there is a problem that the coatability is reduced or even the coating is not possible. In addition, at the time of peeling, the peeling of the peeling layer and the heat-seal layer, the pigment can be peeled from the peeling layer.

[0012] Thus, it is desired to be able to easily manufacture a packaging body which balances the clean peeling property and the heat-seal strength with a simple apparatus and under conditions in which the environmental burden is reduced.

[0013] Thus, it is desired to be able to easily manufacture a packaging body which balances the clean peeling property and the heat-seal strength with a simple apparatus and under conditions in which the environmental burden is reduced.

[0014] Means for solving the problem

[0015] That is, the present application is a laminate in which a base material selected from paper or nonwoven fabric, a peeling layer which is a coated film of a homopolymer or a copolymer of a (meth)acrylate containing microparticles at a ratio of 5% by mass or less with respect to the total amount of the coated film, and a heat-seal layer which is a coated film of an olefin-α, β-unsaturated carboxylic acid copolymer are sequentially laminated.

[0016] In addition, the present application is a packaging body using the above-described laminate.

[0017] Effects of the Invention

[0018] The laminate of the present application can achieve a laminate having both excellent clean peelability and a heat-seal layer by having two layers of a specific peel layer and a specific heat-seal layer provided on a base material selected from paper or nonwoven fabric. In addition, the laminate of the present application can be easily manufactured using simple equipment, and control of heat-seal strength is also easy. Furthermore, since the peel layer and the heat-seal layer of the present application can use an aqueous solvent, environmental burden can be reduced by reduction of VOC. The packaging body using the laminate of the present application can be particularly suitably used in medical sites since it has excellent clean peelability and heat-seal strength. DETAILED DESCRIPTION

[0019] The laminate of the present application has, in order, a base material selected from paper or nonwoven fabric, a peel layer, and a heat-seal layer.

[0020] Note that (meth)acrylate in the present application means the total of acrylate and methacrylate, and (meth)acrylic acid means the total of acrylic acid and methacrylic acid.

[0021] [Peel Layer]

[0022] The peel layer is provided on a base material composed of paper or nonwoven fabric. In the laminate of the present application, by having the peel layer between the base material and the heat-seal layer, excellent clean peelability can be obtained when opening the heat-sealed portion of a packaging body using the laminate.

[0023] The peel layer is a coated film of a homopolymer or a copolymer of (meth)acrylate. The coated film of the peel layer is formed from a composition (peel coating agent) containing at least a homopolymer or a copolymer of (meth)acrylate and an aqueous solvent.

[0024] <Composition for forming the peel layer (peel coating agent)>

[0025] (Homopolymer or copolymer of (meth)acrylate)

[0026] The homopolymer or copolymer of (meth)acrylate is not particularly limited, and as the copolymer, a copolymer obtained by copolymerizing (meth)acrylate with a copolymerizable vinyl monomer can be cited. In addition, from the viewpoint of imparting water dispersibility and water solubility, a copolymer having an acid value is preferred.

[0027] The (meth)acrylate used as a constitutional component of the homopolymer or copolymer of the (meth)acrylate is not particularly limited, however, among them, an acrylate having an alkyl group having a carbon number of 1 to 20 is preferred, from the aspect of exhibiting a lower glass transition temperature, a homopolymer having an acrylate is preferred, preferably an acrylate having an alkyl group having a carbon number of 1 to 20 is used as a main component, preferably an acrylate having an alkyl group having a carbon number of 1 to 12 is used as a main component. As such an acrylate having an alkyl group having a carbon number of 1 to 12, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, allyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl (meth)acrylate, t-butyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-lauryl (meth)acrylate, and the like can be mentioned.

[0028] In addition, as examples of other (meth)acrylates, vinyl monomers capable of copolymerizing with (meth)acrylates, aromatic (meth)acrylates such as benzyl (meth)acrylate; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate; alkyl polyalkylene glycol mono(meth)acrylates such as methoxypolyethylene glycol mono(meth)acrylate, methoxypolypropylene glycol mono(meth)acrylate; fluorine-based (meth)acrylates such as perfluoroalkyl ethyl (meth)acrylate; aromatic vinyl compounds such as styrene, styrene derivatives (p-dimethylsilylstyrene, (p-vinylphenyl)methyl sulfide, p-hexynylstyrene, p-methoxystyrene, p-t-butyldimethylsilyloxystyrene, o-methylstyrene, p-methylstyrene, p-t-butylstyrene, a-methylstyrene, etc.), vinyl naphthalene, vinyl anthracene, 1,1-diphenyl ethylene; (meth)acrylate compounds such as glycidyl (meth)acrylate, epoxy (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol tetra(meth)acrylate, 2-hydroxy-l,3-diacryloyloxypropane, 2,2-bis[4-(acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloyloxyethoxy)phenyl]propane, dicyclopentadiene di(meth)acrylate, tricyclodecanyl (meth)acrylate, tris(acryloyloxyethyl) isocyanurate, urethane (meth)acrylate; (meth)acrylates having an alkylamino group such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate; vinyl pyridine compounds such as 2-vinylpyridine, 4-vinylpyridine, naphthylvinylpyridine; conjugated dienes such as 1,3-butadiene, 2-methyl-l,3-butadiene, 2,3-dimethyl-l,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene; and the like can be mentioned. One of these monomers can be used, or two or more of them can be used in combination.

[0029] In addition, (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, β-(meth)acryloyloxyethyl hydrogen succinate, β-(meth)acryloyloxyethyl hydrogen phthalate, and the like having a carboxyl group are copolymerized for the purpose of introducing one or more acidic groups selected from a carboxyl group and a carboxylate group obtained by neutralizing the carboxyl group with a basic compound, whereby a copolymer having an acid value can be obtained.

[0030] In the case where an acidic group is introduced, the monomer amount is preferably adjusted as appropriate so that the acid value is in the desired range.

[0031] The homopolymer or copolymer of the (meth)acrylate ester can be produced, for example, by polymerizing one or more kinds of monomers in the presence of a polymerization initiator at a temperature ranging from 50°C to 180°C, more preferably from 80°C to 150°C. The method of polymerization can be, for example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, or the like. In addition, the polymerization pattern can be, for example, random copolymer, block copolymer, graft copolymer, or the like. In addition, the copolymer can be of the core-shell type.

[0032] (microparticles)

[0033] The release layer preferably does not contain microparticles, but can contain microparticles. In the case of containing microparticles, the content of microparticles is preferably 25% by mass or less relative to the release layer. By setting the proportion of microparticles in the release layer to 25% by mass or less, the coatability at the time of printing is improved. Thus, it is also easy to adjust the release layer to the desired film thickness. In addition, excellent clean release properties can be obtained, and in addition, the heat seal strength can be improved. In addition, it is possible to prevent microparticles from slipping off at the time of release. The proportion of microparticles in the release layer can be 25% by mass or less, preferably 20% by mass or less, preferably 15% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, more preferably 3% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass or less, more preferably 0.1% by mass or less. It is more preferable that the release layer does not contain microparticles, i.e., 0% by mass or less.

[0034] In the composition for forming the release layer (release coating agent), the content of microparticles can be adjusted so that the microparticles are 25% by mass or less relative to the total amount of the coating film finally formed, for example, preferably 10% by mass or less, preferably 5% or less, preferably 3% or less, preferably 1% or less, preferably 0.5% or less, preferably 0.1% or less, preferably 0% by mass relative to the total amount of the composition.

[0035] The type of microparticles is not particularly limited, and can be any of organic microparticles, inorganic microparticles, and organic-inorganic composite microparticles.

[0036] As the organic microparticles, various kinds of resin beads such as polyolefin-based resins, (meth)acrylate-based resins, polystyrene resins, melamine resins, amide-based resins, urethane-based resins, and the like can be given. As the inorganic microparticles, carbon black, titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silicon dioxide, red iron oxide, aluminum, aluminum hydroxide, mica, clay, talc, kaolin, and the like can be given. Among these, inorganic microparticles such as clay, talc, and kaolin are preferable. In addition, as the organic-inorganic composite microparticles, acrylic-silicone-based microparticles, silicone-based microparticles, and the like can be given. The type of microparticles can be one kind, or a plurality of kinds can be used.

[0037] The particle size of the microparticles is not particularly limited, but from the viewpoint of dispersibility, the average particle size (D50) is preferably 40 μm or less, and more preferably 30 μm or less.

[0038] In order to uniformly disperse the microparticles, it is preferable to perform grinding (Japanese: practice) using a medium, or to perform compounding after a dispersion of the wax has been produced. The grinding method can be performed using a publicly known method.

[0039] (Aqueous solvent)

[0040] Water, a water-soluble organic solvent dissolved in water, or the like can be used as the release coating agent. Purified water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used as the water. In the case of long-term storage of the composition, in order to be able to prevent the generation of mold or bacteria, it is appropriate to use water sterilized by ultraviolet irradiation or hydrogen peroxide addition or the like as the above water.

[0041] As the water-soluble organic solvent, for example, glycols (Japanese: glycol) such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols (Japanese: diol) such as butanediol, pentanediol, and hexanediol; glycol esters such as propylene glycol laurate; diethylene glycol ethers such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and diethylene glycol monohexyl ether; carbitol; glycol ethers such as solvents containing propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether; alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butanol, and amyl alcohol; lactones such as sulfolane, esters, ketones, and γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidine; glycerin and polyalkylene oxide adducts thereof; and other various solvents known as water-soluble organic solvents can be used. These water-soluble organic solvents can be used alone or in combination with two or more. Of these, water is most preferable.

[0042] (Other additives)

[0043] The release coating agent can be compounded with additives such as waxes, defoaming agents, leveling agents, tackifiers, preservatives, antibacterial agents, and rust preventives, in addition to the above components, within a range that does not interfere with the purpose of the present application. In addition, other resins other than homopolymers or copolymers of (meth)acrylates can also be compounded.

[0044] The type of the leveling agent is not particularly limited, but an acetylenic surfactant is preferably used. As the acetylenic surfactant, specifically, 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-l-hexyne-3-ol, 3-methyl-l-butyne-3-ol, 3-methyl-l-pentyne-3-ol, 3-hexyne-2,5-diol, 2-butyne-l,4-diol, and the like can be mentioned. In addition, as commercially available products, non-alkylene oxide-modified acetylenic diol-based surfactants such as Surfynol 61, 82, 104 (all manufactured by Air Products), alkylene oxide-modified acetylenic diol-based surfactants such as Surfynol 420, 440, 465, 485, TG, 2502, Dynol 604, 607 (all manufactured by Air Products), Surfynol SE, MD-20, OLFINE E1004, E1010, PD-004, EXP4300, PD-501, PD-502, SPC (all manufactured by Nissin Chemical Industry Co., Ltd.), Acetylenol EH, E40, E60, E81, E100, E200 (all manufactured by Kawaken Fine Chemicals, Ltd.), and the like can be mentioned.

[0045] The amount of the leveling agent to be added is preferably 0.01 to 0.1 mass% of the total amount of the composition forming the release layer.

[0046] In the release layer of the present application, in order to prevent the composition from foaming when the release coating agent is applied to paper, a polymer-based defoaming agent, a silicon-based defoaming agent, a fluorine-based defoaming agent are preferably incorporated. As these defoaming agents, any of emulsion dispersion type, solubilized type, and the like can be used. Among them, a polymer-based defoaming agent is preferred. The amount of the defoaming agent to be added is preferably 0.005 to 0.1% by weight of the total amount of the release coating agent.

[0047] <Method for forming the release layer>

[0048] The release layer of the present application is preferably formed using a release coating agent containing a (meth)acrylate homopolymer or copolymer and an aqueous solvent, and, as needed, microparticles and other additives. The release layer can be provided, for example, by using paper or nonwoven fabric as a substrate and coating on the substrate.

[0049] As a method when the release coating agent is applied to the substrate, a publicly known method can be used. For example, any one of a comma-type doctor blade coater, a roll coater, a reverse roll coater, a direct slot-die coater, a reverse slot-die coater, a compensation slot-die coater, a kiss coater, a contact-type reverse coater, a contact-type slot-die coater, a contact-type reverse slot-die coater, an air doctor coater, a blade coater, a bar coater, a wire bar coater, a die coater, a die lip coater, a dip coater, a blade coater, a brush coater, a curtain coater, a die slot coater, an offset printer, a screen printer, or the like, or a combination of two or more of the coating methods can be used.

[0050] In addition, the release layer can be provided on the substrate by immersing the substrate in the release coating agent. In the case of immersion, a mechanism for immersion needs to be separately provided, whereas in the case of application, printing based on a general printer as described above can be used to easily produce, and thus the application method is more preferable. In addition, in the case of immersion, it is difficult to control the thickness (amount) of the release layer, and in addition, the drying process takes more time compared to the case of application, and there is a case where the substrate is deformed due to drying, and thus the application is preferable.

[0051] In addition, a drying process in which drying is performed in an oven or the like can be provided after the application.

[0052] The amount of the release layer at the time of application is preferably, for example, in the range of 1.0 to 8.0 g / m 2 . If it is in this range, the effects of the present application can be sufficiently obtained. Among them, the range of 2 to 6 g / m 2 is more preferable.

[0053] [Heat-seal layer]

[0054] In the laminate, the heat-seal layer is provided on the release layer. The heat-seal layer of the present application forms a package by adhering an adherend to the laminate using a heat-seal function.

[0055] The heat-seal layer is a coating film of an olefin-α, β unsaturated carboxylic acid copolymer. The coating film of the heat-seal layer is formed using a composition (coating agent) containing at least an olefin-α, β unsaturated carboxylic acid copolymer and an aqueous solvent.

[0056] [Composition (aqueous heat-seal agent) for forming heat-seal layer]

[0057] (Olefin-α, β unsaturated carboxylic acid copolymer)

[0058] As the olefin-α,β-unsaturated carboxylic acid copolymer used in the heat-seal layer, a copolymer of an olefin and at least one monomer selected from the group consisting of an α,β-unsaturated carboxylic acid, a metal salt of an α,β-unsaturated carboxylic acid, and an α,β-unsaturated carboxylic acid ester, or the like can be given. Specifically, a copolymer of an α,β-unsaturated carboxylic acid, a metal salt of an α,β-unsaturated carboxylic acid, or an α,β-unsaturated carboxylic acid ester and an olefin can be given, and an olefin-α,β-unsaturated carboxylic acid copolymer, an ethylene-acrylate copolymer, an ethylene-methacrylic acid copolymer, an ethylene-methacrylate copolymer, an ethylene-acrylic acid-maleic anhydride copolymer, an ethylene-acrylate-maleic anhydride copolymer, an ethylene-methacrylic acid-maleic anhydride copolymer, an ethylene-methacrylate-maleic anhydride copolymer, and a metal salt thereof, or the like can be given. These copolymers can be one alone or a mixture of two or more.

[0059] Among these, an olefin-α,β-unsaturated carboxylic acid copolymer is preferable. As the olefin-α,β-unsaturated carboxylic acid copolymer, a random copolymer or a block copolymer of ethylene and an α,β-unsaturated carboxylic acid can be given.

[0060] As the above olefin, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, butadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, or the like can be given. Among these, ethylene is preferable.

[0061] As the above α,β-unsaturated carboxylic acid, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, or the like can be given. Among these, acrylic acid and methacrylic acid can be suitably used. These α,β-unsaturated carboxylic acids can be used alone or two or more can be used in combination.

[0062] As the above α,β-unsaturated carboxylic acid ester, a publicly known alkyl ester, a hydroxyalkyl ester, an alkoxyalkyl ester, or the like of acrylic acid or methacrylic acid can be used without particular limitation. Specifically, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, n-octyl acrylate, 2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, or the like acrylate ester; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-ethoxyethyl methacrylate, or the like methacrylate ester can be given. One or two or more of these can be used in combination.

[0063] As the method for producing the above-described olefin-α,β-unsaturated carboxylic acid copolymer, a publicly known method such as radical copolymerization under high temperature and high pressure can be used.

[0064] The content of the α,β-unsaturated carboxylic acid in the above-described olefin-α,β-unsaturated carboxylic acid copolymer is desirably 8 to 24% by weight, and preferably 18 to 23% by weight. In the case where the content of the α,β-unsaturated carboxylic acid is less than 8% by weight, the dispersibility in a water-based dispersing medium is poor due to the nonpolar nature from the ethylene unit, and it can be difficult to obtain an excellent aqueous dispersion of the olefin-α,β-unsaturated carboxylic acid copolymer resin. In the case where the content of the α,β-unsaturated carboxylic acid is more than 24% by weight, the obtained film can have poor blocking resistance.

[0065] The olefin-α,β-unsaturated carboxylic acid copolymer used in the heat sealant is used in the form of an aqueous dispersion dispersed in a water-based solvent. As the method for dispersing in a water-based solvent, there is no particular limitation, and a publicly known method can be used. For example, a method in which the olefin-α,β-unsaturated carboxylic acid copolymer is emulsified with a surfactant to be dispersed in a water-based solvent, a method in which the olefin-α,β-unsaturated carboxylic acid copolymer is neutralized with an alkaline compound to be dispersed in a water-based solvent, and the like can be given.

[0066] As the surfactant used when the above-described emulsification is performed, various anionic, cationic, nonionic surfactants, or various water-soluble polymers known per se can be appropriately used in combination.

[0067] In addition, as the alkaline compound used when the above-described neutralization is performed, for example, organic amines such as ammonia, methylamine, ethylamine, diethylamine, dimethylethanolamine, diethanolamine, and triethanolamine; and alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide can be given. These alkaline compounds can be used alone or in combination with two or more.

[0068] The degree of neutralization with the alkaline compound is only required to be a degree at which the olefin-α,β-unsaturated carboxylic acid copolymer is stably present in the water-based solvent. For example, 30 to 100 mol% of the carboxyl group of the copolymer, and more preferably 40 to 90 mol% can be given.

[0069] As the dispersion method, a publicly known method can be used. For example, as the dispersion device using a medium, a paint shaker, a ball mill, a mortar mill, a basket mill, a sand mill, a sand grinder, a DYNO-MILL, a DISPERMAT, an SC mill, a pin mill, a sand grinder, and the like can be used, and as the dispersion device not using a medium, an ultrasonic homogenizer, a high-pressure homogenizer, a nanomizer, a dissolver, a disperser, a high-speed impeller disperser, and the like can be used.

[0070] The solid content of the aqueous dispersion of the olefin-α,β-unsaturated carboxylic acid copolymer used in the present application is not particularly limited, and is appropriately determined in accordance with the desired viscosity when used as a heat sealant, the drying conditions after application of the heat sealant, the film thickness of the film, and the like. In general, use is often made in the range of 10 to 40% by mass of the solid content concentration.

[0071] (aqueous solvent)

[0072] As the aqueous solvent, the same aqueous solvent as that used in the composition used in the above-mentioned release layer can be used.

[0073] (wax)

[0074] The heat sealant preferably contains a wax. By containing a wax, anti-blocking properties can be ensured. As the above-mentioned wax (W1), for example, fatty acid amide wax, carnauba wax, polyolefin wax, paraffin wax, Fischer-Tropsch wax, beeswax, microcrystalline wax, oxidized polyethylene-wax, amide wax, and the like can be mentioned. These can be used alone or in combination.

[0075] Among these, polyolefin wax, fatty acid amide wax, carnauba wax, and Fischer-Tropsch wax are preferable, and polyolefin wax, fatty acid amide wax, and carnauba wax are particularly preferable.

[0076] As specific examples of the fatty acid amide wax, for example, nonanamide, decanoic acid amide, undecanoic acid amide, lauric acid amide, tridecanoic acid amide, myristic acid amide, pentadecanoic acid amide, palmitic acid amide, margaric acid amide, stearic acid amide, nonadecanoic acid amide, arachidic acid amide, behenic acid amide, lignoceric acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, mixtures thereof, and animal and vegetable oil fatty acid amides can be mentioned.

[0077] As specific examples of the above-mentioned carnauba wax, MICROKLEAR 418 (Micro Powders, Inc.), refined carnauba wax No. 1 powder (Nippon Seiro Co., Ltd.), and the like can be mentioned.

[0078] As the polyolefin wax, polyethylene-based wax, polypropylene-based wax, and the like can be mentioned.

[0079] As to the blending amount of the above-mentioned wax, the total amount of the wax is preferably 1.5 to 25% by mass with respect to the total amount of 100% by mass of the solid content of the heat sealant. If the total amount of the wax is 1.5% by mass or more with respect to the total amount of 100% by mass of the solid content of the heat sealant, there is a tendency to be able to maintain anti-blocking properties, and if the total amount of the wax (W1) is 25% by mass or less with respect to the total amount of 100% by mass of the solid content of the heat sealant, there is a tendency to be able to maintain heat sealability.

[0080] In addition, the amount of the wax is preferably 1 to 5 mass% of the total amount of the composition for forming the heat-seal layer.

[0081] Among the above-mentioned waxes, if the above-mentioned fatty acid amide wax and the above-mentioned carnauba wax are used in combination, the anti-blocking property is further improved, and thus is more preferable. In the case of using in combination, the ratio is not particularly limited, but the range of fatty acid amide wax : the above-mentioned carnauba wax = 1 : 1 to 1 : 10 is preferable, and the range of 1 : 1 to 1 : 5 is more preferable.

[0082] The above-mentioned wax can be directly added to the aqueous dispersion of the above-mentioned olefin-α, β unsaturated carboxylic acid copolymer and mixed and dispersed, or can be simultaneously added and mixed and dispersed when the above-mentioned olefin-α, β unsaturated carboxylic acid copolymer is dispersed in the aqueous solvent. The dispersion method can be appropriately applied to the method used in the above-mentioned dispersion method of the above-mentioned olefin-α, β unsaturated carboxylic acid copolymer in the aqueous solvent.

[0083] In addition, in the case of using a plurality of waxes in combination, the plurality of waxes can be simultaneously added, or can be added in a plurality of steps. For example, the heat-seal agent containing the wax can be obtained by the following method, that is, after adding a first wax when the above-mentioned olefin-α, β unsaturated carboxylic acid copolymer is dispersed in the aqueous solvent, a second wax is further added to the obtained aqueous dispersion of the first wax and the above-mentioned olefin-α, β unsaturated carboxylic acid copolymer. The amount and kind of the leveling agent can be the same as those used in the release coating agent.

[0084] (Leveling agent)

[0085] The heat-seal agent preferably contains a leveling agent. By containing the leveling agent, the occurrence of pinholes in the coating film can be prevented. The kind of the leveling agent is not particularly limited, and the same substance as the leveling agent exemplified as the one that can be used in the above-mentioned release layer can be used. As the amount of the leveling agent to be added, 0.01 to 0.1% by weight of the total amount of the composition for forming the release layer is preferable.

[0086] The heat-seal agent can be compounded with additives such as silica, alumina, a defoaming agent, a viscosity adjusting agent, a tackifier, a preservative, an antibacterial agent, an antirust agent, an antioxidant, silicone oil, and the like, in a range not obstructing the object of the present application.

[0087] In addition, in the heat-seal agent, in order to prevent the occurrence of foaming at the time of coating using various coating machines, a polymer-based defoaming agent, a silicone-based defoaming agent, a fluorine-based defoaming agent are preferably used. As these defoaming agents, any one of emulsion dispersion type, solubilized type, and the like can be used. Among them, the polymer-based defoaming agent is preferable. As the amount of the defoaming agent to be added, 0.005 to 0.1% by weight of the total amount of the aqueous heat-seal agent is preferable.

[0088] <Method for forming heat-seal layer>

[0089] The heat seal layer is provided by applying the above-mentioned heat sealant to the release layer, for example. As the coating method at the time of application, a publicly known method can be used. For example, a roll coater, a slot coater, a blade coater, an air doctor coater, a knife coater, an air knife coater, a squeeze coater, a dip coater, a transfer roll coater, a kiss coater, a curtain coater, a flow coater, a spray coater, a curtain coater, an offset printer, a screen printer, and the like can be used. In addition, a drying process in which drying is performed in an oven or the like after application can also be provided.

[0090] The amount of the heat seal layer at the time of application is preferably, for example, 1.0 to 8.0 g / m2of the substrate. In the case where the amount of the heat seal layer is less than 1.0 g / m2of the substrate, the heat seal strength tends to be poor. On the other hand, in the case where the amount of the heat seal layer is more than 5.0 g / m2of the substrate, when the heat seal portion becomes the adhesion portion, a part of the paper or nonwoven fabric substrate tends to be peeled off, impairing clean peeling properties. It is more preferable that the amount of the heat seal layer be in the range of 1.5 to 6 g / m2of the substrate, and further preferable that the amount of the heat seal layer be in the range of 3 to 5 g / m2of the substrate. By adjusting the amount of the heat seal layer, it is possible to easily adjust the heat seal strength to a desired value. 2 2 2 2 2

[0091] The heat sealant has a function as an adhesive, that is, an aqueous heat sealant is applied to a substrate, and the substrate and an adherend are adhered in a state of being overlapped via the heat sealant. Specifically, after the heat sealant is applied to the release layer provided on the substrate, it is softened by heating. By heating using a burner, hot air, or the like, the heat sealant can be easily softened, and the substrate and the adherend can be adhered. Thereafter, by performing cooling, the adhesion portion is cured, and the substrate and the adherend can be firmly sealed.

[0092] As the heating method, a publicly known method such as a heat source such as a burner, hot air, electric heating, infrared rays, an electron beam, or the like can be used. Specifically, a method in which heating is performed using a burner or hot air, a heat fusion sealing method selected in accordance with the form of molding, an ultrasonic sealing method, or a high frequency sealing method is preferable. The heating temperature at this time is preferably in the range of 120°C to 500°C, and the heating time is preferably in the range of 0.1 to 3 seconds. The heat seal layer of the present application can obtain a heat seal strength of 4 N / 15 mm or more, which is sufficient for use as a medical packaging material, even at a relatively low temperature of 120°C or higher. In addition, since heat sealing can be performed in a wide temperature range, the heat seal strength can be easily adjusted, and manufacturing can be easily performed. From the viewpoints of the heat seal strength and the ease of manufacturing, it is preferable that heat sealing be performed in the range of 120°C to 200°C, and more preferably in the range of 130°C to 180°C.

[0093] ​​​​​In addition, the heat-sealing agent is easily heated and softened even by non-contact heating, and the heat-sealing function continues for a certain period of time even after being removed from the heat source. In the case where the base material is paper, the paper can be scorched if it is in contact with a direct heat source, but the heat-sealing agent of the present application is particularly useful as a heat-sealing agent for industrial production of paper containers that require high-speed production line speeds, because it exhibits a heat-sealing function by non-contact heating and this function continues.

[0094] After the heat-sealing agent is applied and the coated portion is heated and softened, the coated portion is pressure-bonded to the adherend in an overlapping state, whereby it can be used as a heat-sealing agent. The pressure-bonding method is not particularly limited, and can be performed by a hot plate method, an ultrasonic sealing method, or a high-frequency sealing method.

[0095] [Base material]

[0096] The base material paper of the present application is selected from paper or nonwoven fabric.

[0097] As the paper base material, a natural fiber for papermaking such as wood pulp is used to be manufactured by a known papermaking machine, and the papermaking conditions are not particularly specified. As the natural fiber for papermaking, coniferous pulp, broadleaf pulp, Manila hemp pulp, sisal hemp pulp, flax pulp, and the like can be given, and pulp obtained by chemically modifying these pulps can also be used. As the type of pulp, chemical pulp based on the sulfite digestion method, acid / neutral / alkali sulfite digestion method, sodium salt digestion method, and the like, ground pulp, chemically ground pulp, thermomechanical pulp, and the like can be used. In addition, various high-grade papers, art paper, backing paper, impregnated paper, corrugated paper, board paper, and the like available on the market can also be used.

[0098] As the nonwoven fabric, a nonwoven fabric obtained by heat-fusing fibers of a thermoplastic resin such as polyolefin, which is formed into a fiber shape, can be used.

[0099] The above base material can be selected in terms of the type, thickness, and the like of the paper or nonwoven fabric as desired. For example, in the case where gas sterilization is to be performed in a medical packaging material, it is appropriate to select from the viewpoint of moderate air permeability and strength as a base material, and specifically, the square meter basis weight is preferably 30 to 300 g / m 2 , preferably 40 to 200 g / m 2 , and more preferably 50 to 100 g / m 2 . On the other hand, in the case where the laminate of the present application is used as a container such as a paper cup, paper tray, or paper packaging material, the square meter basis weight is preferably 200 to 350 g / m 2 , and more preferably 200 to 300 g / m 2 .

[0100] The base material of the paper or nonwoven fabric can have a printed layer.

[0101] [Package]

[0102] The laminate of the present application can be processed into a box, bag, or container by heat sealing with the heat sealable coating portion.

[0103] The package can be, for example, a bag for packaging, a paper bag, a carton, corrugated paper, wrapping paper, an envelope, a cup sleeve, a lid, and the like. As the container, a paper container, a paper tray, a tray, a cup holder, a paper cup, and the like can be mentioned. The water-resistant paper of the present application can be used for foods, groceries, household goods, and the like that require water resistance and moisture resistance. For example, a cup or lid for a cup noodle, ice cream, pudding, jelly, and the like, a snack bag or box, a wrapping paper for a hamburger, a hot dog, a container for a pizza and the like, a container for a hot snack of a dry-fried food, a potato, and the like, a paper container or packaging material for foods such as a cup for a side dish of natto and the like, a bag or box for sanitary goods represented by a detergent, a sanitary good, and the like can be mentioned. The release layer and the heat sealable layer can be provided on the inner side of the packaging material or the container corresponding to these uses, or can be provided on the outer side, or can be provided on both sides of the base material.

[0104] In the case where the laminate of the present application is used to produce a paper cup, the paper cup can be produced by providing the heat sealable layer on the inner surface of the container and the adhering surface at the time of assembling the container, and bonding the heat sealable layer. That is, the paper cup has a main body member (1) obtained by bonding the adhering surfaces of the two end portions of the wound paper base material using the laminate of the present application, and a plate-like bottom member (2) bonded to the lower end of the main body member (1), and has the heat sealable layer at least at the bonding portion. The heat sealable layer can be provided only on the bonding portion, or can be provided on the entire paper base material.

[0105] Similarly, the laminate of the present application can be used to produce a carton, a paper bag, and the like with the heat sealable layer as the bonding portion.

[0106] Since the laminate of the present application can achieve both excellent heat sealability and clean release, it is preferably used as a package having easy openability, and is preferably used as a medical packaging material for packaging sterilization equipment for medical use.

[0107] In the case where the laminate is used for a package as described above, a bag, a box, or wrapping paper can be produced by separately using the laminate and sealing the heat sealable coating portion, or the laminate can be used to produce a package obtained by overlapping the laminate with an adherend and bonding via the heat sealable layer.

[0108] In the case of use as a medical packaging material, the laminate is preferably overlapped with an adherend such as a plastic film and heat-sealed at the peripheral edge portion. The peeling layer and the heat-sealing layer can be provided at least in the heat-sealing portion in the base material. Thus, the peeling layer and the heat-sealing layer can be provided only in the portion to be heat-sealed, or can be provided on the entire surface of at least one surface of the base material.

[0109] In the packaging body, in the case of heat-sealing the laminate with an adherend, the adherend is not particularly limited, and various base materials such as paper, nonwoven fabric, plastic film, and the like can be used. The material of the plastic film is not particularly limited. As a representative plastic film base material, a film of a thermoplastic resin such as a film containing a polyamide resin such as nylon 6, nylon 66, nylon 46, polyethylene terephthalate (hereinafter sometimes referred to as PET), polyethylene naphthalate, polypropylene terephthalate, polypropylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, a biodegradable resin such as a polyhydroxy carboxylic acid such as polylactic acid, an aliphatic polyester resin such as poly(ethylene succinate), poly(butylene succinate), a polyolefin resin such as polypropylene, polyethylene, a polyimide resin, a polyarylate resin, or a mixture thereof, and a laminate thereof can be mentioned, and a film containing PET, a polyester, a polyamide, polyethylene, and polypropylene can be suitably used. These base material films can be unstretched films or stretched films, and the production method is not limited. In addition, the thickness of the base material film is not particularly limited, and is usually in the range of 1 to 500 μm. In addition, the surface can be subjected to corona treatment.

[0110] The heat-sealing strength of the packaging body of the present application is preferably in the range of 4 N / 15 mm or more and 10 N / 1.5 mm or less. In the case of use as a medical packaging material, if the heat-sealing strength is in the above range, both sufficient heat-sealing strength and easy openability can be achieved.

[0111] The packaging body of the present application is opened by peeling the heat-sealed portion at the time of opening. At this time, the opening is performed by the interface between the peeling layer and the heat-sealing layer or the interlayer peeling in the peeling layer, and thus the paper or nonwoven fabric can be prevented from being peeled. In addition, the peeling layer does not contain fine particles, and even if fine particles are contained, the content is 25% by mass or less, and thus the coatability of the peeling layer and the prevention of the detachment of fine particles from the peeling layer can be ensured, and a more excellent clean peeling property can be obtained.

[0112] Hereinafter, the present application will be described in detail based on Examples, but the technical scope of the present application is not limited by these Examples.

[0113] Example

[0114] In the following Examples, "parts" means "parts by mass", and "%" means "% by mass".

[0115] Method for producing olefin-α, β-unsaturated carboxylic acid copolymer

[0116] (Production Example 1)

[0117] Ethylene 77.8 parts, ethyl acrylate 11.1 parts, and acrylic acid 11.2 parts were synthesized by a usual method to obtain an ethylene-ethyl acrylate-acrylic acid copolymer.

[0118] The obtained copolymer 25 parts, ammonia whose neutralization rate reached 100% with respect to the acid value of the copolymer, and water as an aqueous solvent were added, and stirring was performed to obtain an aqueous dispersion of an olefin-α, β-unsaturated carboxylic acid copolymer (Al).

[0119] (Production Example 2)

[0120] Ethylene 77.8 parts, ethyl acrylate 11.1 parts, and acrylic acid 11.2 parts were synthesized by a usual method to obtain an ethylene-ethyl acrylate-acrylic acid copolymer.

[0121] The obtained copolymer 25 parts, ammonia whose neutralization rate reached 100% with respect to the acid value of the copolymer, water as an aqueous solvent, and a fatty acid amide wax 1.5 parts as a wax were added, and stirring was performed to obtain an aqueous dispersion of an olefin-α, β-unsaturated carboxylic acid copolymer and a fatty acid amide wax (A2).

[0122] Preparation of heat sealant

[0123] (Examples 1 to 12 and Comparative Examples 1 to 4)

[0124] Using the aqueous dispersion (Al) or (A2) obtained in Production Example 1 or Production Example 2, a heat sealant of the example or the comparative example was obtained in accordance with the composition of Table 1 or 2.

[0125] The wax 1 in the table used a polyethylene-based wax.

[0126] In addition, the leveling agent in the table used an ethylene glycol-based surfactant.

[0127] In addition, in Comparative Example 1, a commercially available aqueous acrylic emulsion was used as an aqueous acrylic heat sealant.

[0128] In addition, in Comparative Example 2, a coating liquid obtained by dispersing ethylene-vinyl acetate copolymer 100 parts by mass in ion exchange water 10 parts by mass was used as an aqueous EVA heat sealant.

[0129] In addition, in Comparative Example 3, a coating liquid obtained by dissolving ethylene-vinyl acetate copolymer 20 parts by mass in toluene 75 parts by mass and isopropyl alcohol 5 parts by mass was used as a solvent-based EVA heat sealant.

[0130] Preparation of release agent

[0131] (Examples 1 to 12 and Comparative Example 4)

[0132] As the homopolymer or copolymer of (meth)acrylate, an aqueous acrylic emulsion (Chemipearl (registered trademark) manufactured by Mitsui Chemicals, Inc.) was used.

[0133] The clay in the table used kaolin clay (ASP-170 (manufactured by BASF Corporation)).

[0134] Note that in Table 1, the blending ratio of the acrylic resin emulsion used in the release agent composition, and the water dispersions (Al) and (A2) used in the heat sealant composition indicates the ratio of the resin solid content.

[0135] <Manufacture of the laminate>

[0136] (Examples 1 to 12, Comparative Examples 1 to 4)

[0137] After the release coating agent of the example or comparative example was coated on the nonwoven fabric (high-density polyethylene nonwoven fabric (trade name: Tyvek 1073B, grammage per unit area 75 g / m2, manufactured by Asahi-Dupont Flash Spun Products Corporation) using a bar coater #16, it was dried at 150°C for 20 seconds to form a release layer. Next, after the heat sealant of the example or comparative example was coated on the release layer using a bar coater #16, it was dried at 150°C for 20 seconds, and the laminate of Examples 1 to 12 and Comparative Example 4 was manufactured, respectively. 2

[0138] In addition, in Comparative Examples 1 to 3, the heat sealant of Comparative Examples 1 to 3 was coated on the nonwoven fabric used in Example 1 using a bar coater #16, and dried at 150°C for 20 seconds, and the laminate of Comparative Examples 1 to 3 was manufactured, respectively.

[0139] Note that the coating amount of the release coating layer and the heat seal layer was performed at the respective coating amounts shown in Tables 1 and 2.

[0140] <Evaluation>

[0141] (Heat seal strength)

[0142] The laminate of Examples 1 to 12 and Comparative Examples 1 to 4 was cut into 3.0 cm x 5.0 cm, and the coated surface of the laminate was overlapped with a polyethylene / polyester laminated film (thickness 60 μm) as an adherend so that the polyethylene side of the film faced the heat seal layer, and after heating at each temperature shown in the table at a temperature of 130°C to 170°C, heat sealing was performed immediately using a heat sealer under a pressure of 0.3 MPa, a close contact condition of 1.5 seconds, and thus a heat seal portion was provided.

[0143] ​The laminate provided with the heat-sealed portion was cut out to 15 mm in width, and the peeling strength at the time of sharp peeling under the conditions of a stretching speed of 200 mm / min and 180-degree peeling was measured. Note that the determination criteria are shown below.

[0144] (Evaluation)

[0145] 5: The sealing strength is 6 N / 15 mm or more;

[0146] 4: The sealing strength is 5 N / 15 mm or more and less than 6 N / 15 mm;

[0147] 3: The sealing strength is 4 N / 15 mm or more and less than 5 N / 15 mm;

[0148] 2: The sealing strength is 3 N / 15 mm or more and less than 4 N / 15 mm;

[0149] 1: The sealing strength is less than 3 N / 15 mm.

[0150] (Clean Peeling Property)

[0151] In the evaluation of the heat-sealability described above, the surface state of the heat-sealed portion after sharp peeling under the conditions of a stretching speed of 200 mm / min and 180-degree peeling was evaluated in terms of the occurrence of peeling and breakage of the nonwoven fabric.

[0152] (Evaluation)

[0153] O: The coating layer (peeling coating agent) remains on the nonwoven fabric (interlayer peeling of the coating layer), and no peeling and breakage of the nonwoven fabric occurs.

[0154] Δ: There is a portion in which a part of the coating layer (peeling coating agent) is peeled, and peeling and breakage of the nonwoven fabric occur.

[0155] X: 30% or more of the coating layer (peeling coating agent) is peeled, and peeling and breakage of the nonwoven fabric occur in a large area.

[0156] (Blocking Resistance)

[0157] The laminates of Examples 1 to 12 and Comparative Examples 1 to 4 were overlapped so that the coated surface and the uncoated surface (the surface on the opposite side to the coated surface) of each of the laminates were in contact with each other, and a load of 10 kgf / cm 2 was applied thereto. After 48 hours in an environment at 40°C, the adhesion state of the coated surface and the uncoated surface was visually evaluated in accordance with the following four grades.

[0158] (Evaluation)

[0159] ◎: No blocking was observed at all.

[0160] O: Slight blocking was observed in part.

[0161] Δ: Partially observed adhesion.

[0162] X: Observed adhesion throughout the surface.

[0163] [Table 1]

[0164]

[0165] [Table 2]

[0166]

[0167] [Table 3]

[0168]

[0169] According to Examples 1 to 12, the laminate having a release layer and a heat seal layer of the present application can achieve both heat sealability and clean release properties at a level equivalent to the solvent-based EVA heat sealant used in Comparative Example 3. Examples 1 to 12 can reduce environmental burden because water-based solvents are used, and can be manufactured using simple equipment because the heat seal layer does not need to be thickly applied. In addition, adhesion can be improved compared to Comparative Example 3.

[0170] In addition, Comparative Example 1, which used a water-based acrylic heat sealant, resulted in a poor heat sealability of 130 to 170°C, whereas the laminate of the present application has excellent heat sealability at a low temperature of 130 to 170°C, and can exhibit excellent heat sealability in a large temperature range.

[0171] In addition, Comparative Example 4, which contained 15 mass% of clay in the composition for forming a release agent, had a reduced solid content viscosity when adjusted to an appropriate viscosity at the time of printing, and could not be applied.

Claims

1. A laminated body, characterized in that, It consists of a substrate, a release layer, and a heat-sealing layer stacked in sequence. The substrate is selected from paper or non-woven fabric. The release layer is a coating film of a homopolymer or copolymer of (meth)acrylate, containing particulate matter at a proportion of less than 25% by mass relative to the total solid content of the coating film. The heat-sealing layer is a coating film of an olefin-α,β-unsaturated carboxylic acid copolymer. The α,β unsaturated carboxylic acid content in the olefin-α,β unsaturated carboxylic acid copolymer is 8% to 24% by weight.

2. The laminated body according to claim 1, wherein, The heat-sealing layer contains wax and / or leveling agent.

3. The laminate according to claim 1 or 2, wherein, The amount of the heat-sealing layer is 1.0 g / m. 2 ~8.0g / m 2 .

4. The laminate according to claim 1 or 2, wherein, The amount of the peeling layer is 1.0 g / m 2 ~8.0g / m 2 .

5. The laminate according to claim 1 or 2, wherein, The laminate is sterilized paper or sterilized nonwoven fabric.

6. A packaging body obtained by bonding a laminate according to any one of claims 1 to 5 to an object to be bonded via a heat-sealing layer disposed on the laminate.

7. The packaging body according to claim 6, wherein, The heat-sealing layer is disposed at the periphery of the laminate, and the adhered material is heat-sealed at the periphery.

8. The packaging body according to claim 6 or 7, wherein, The object to be adhered to is a plastic film.

9. The packaging body according to claim 6 or 7, wherein, The bonding strength between the laminate and the adherend is in the range of 4N / 15mm or more and 10N / 1.5mm or less.

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