Adhesive sheet

Abstract

Provided is an adhesive sheet having a substrate and a hot-melt adhesive layer that includes a softener, the adhesive sheet furthermore having a barrier layer that is arranged between the substrate and the hot-melt adhesive layer and that contains at least one selected from the group consisting of polyester-based resins, polyurethane-based resins, and polyolefin-based resins, and the polyester-based resins being at least either polyester resins or modified polyester resins.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet.

Background Art

[0002] Conventionally, adhesives have shown excellent performance in flexibility, elasticity, adhesiveness, etc., and have been widely used in the applications of adhesive sheets. As a manufacturing method of the adhesive, a solvent method in which rubber or the like is dissolved in a solvent, the solution is applied to a substrate, and then heated to dry the solvent has been common. However, this manufacturing method by the solvent method has drawbacks such as requiring a long time to dissolve rubber or the like in a solvent.

[0003] Therefore, in recent years, hot-melt adhesives that can be applied to a substrate by heat melting have been preferably used (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in an adhesive sheet in which a hot-melt adhesive layer made of a hot-melt adhesive is formed on a substrate, there are problems that a paper substrate discolors or a substrate containing a polyolefin-based resin is deformed (curl, deflection, elongation, etc. occur). As a result of investigations by the present inventor, softeners such as process oils are added to hot-melt adhesives in order to improve coatability or to exhibit adhesiveness at low temperatures. It has been found that the discoloration and deformation of the substrate occur due to the transfer of this softener from the hot-melt adhesive layer to the substrate. The present invention aims to provide an adhesive sheet that can suppress the migration of a softening agent contained in the hot melt adhesive layer to the substrate, thereby suppressing discoloration and deformation of the substrate. [Means for solving the problem]

[0006] The inventors of the present invention have found that the above problems can be solved by arranging a barrier layer containing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins between the substrate and the hot melt adhesive layer, and have completed the present invention. In other words, the present invention provides the following [1] to [9]. [1] An adhesive sheet having a base material and a hot melt adhesive layer containing a softening agent, The substrate and the hot-melt adhesive layer are disposed between them and further comprise a barrier layer containing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins. The aforementioned polyester resin is at least one of polyester resin and modified polyester resin, in an adhesive sheet. [2] The adhesive sheet according to [1], wherein the polyester resin and the polyurethane resin each have a glass transition temperature of 40 to 130°C, and the polyolefin resin has a softening point of 0 to 100°C. [3] The adhesive sheet according to [1] above, wherein the glass transition temperature of the polyester resin is 20 to 100°C. [4] The adhesive sheet according to any one of [1] to [3] above, wherein the substrate comprises at least one of paper and an olefin resin. [5] The density of the paper is 0.9 g / cm³. 3 The adhesive sheet described in [4] above. [6] The adhesive sheet according to any one of the above [1] to [5], wherein the thickness of the barrier layer is 0.01 to 10 μm. [7] The adhesive sheet according to [1] or [3] above, wherein the polyester resin has a glass transition temperature of 30 to 90°C. [8] The adhesive sheet according to any one of the above [1] to [7], wherein the hot melt adhesive layer is a layer containing rubber and a tackifier. [9] The adhesive sheet according to any one of the above [1] to [8], further comprising a release liner on the hot melt adhesive layer opposite to the barrier layer. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an adhesive sheet that can suppress the migration of the softening agent contained in the hot melt adhesive layer to the substrate, thereby suppressing discoloration and deformation of the substrate. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing the structure of an adhesive sheet according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the structure of an adhesive sheet according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0009] In this specification, "weight-average molecular weight" is based on polystyrene equivalent calculated by gel permeation chromatography (GPC). Furthermore, the lower and upper limits, which are described in stages for a preferred numerical range (for example, a range for content, etc.), can be combined independently. For example, from a description such as "preferably 10 to 90, more preferably 30 to 60," the "preferred lower limit (10)" and the "more preferred upper limit (60)" can be combined to arrive at "10 to 60."

[0010] [Composition of the adhesive sheet] The adhesive sheet of the present invention is not particularly limited in its configuration, as long as it has a barrier layer between the substrate and the hot-melt adhesive layer. The barrier layer is provided for the purpose of suppressing the migration of the softening agent contained in the hot-melt adhesive layer to the substrate. The adhesive sheet of the present invention may have other layers between the substrate and the barrier layer, and between the barrier layer and the hot melt adhesive layer, but it is preferable that there are no other layers between the substrate and the barrier layer, and between the barrier layer and the hot melt adhesive layer, and that the substrate, barrier layer, and hot melt adhesive layer are directly laminated in this order. In the adhesive sheet of the present invention, a release liner or the like may be provided on the hot melt adhesive layer opposite the barrier layer, or a printed coating layer or the like may be provided on the substrate opposite the barrier layer. In addition, the adhesive sheet of the present invention may include other layers that do not correspond to the above-mentioned substrate, barrier layer, hot melt adhesive layer, release liner, and printed coating layer.

[0011] Figure 1 is a cross-sectional view showing the configuration of an adhesive sheet according to the first embodiment of the present invention. In the adhesive sheet 1a according to the first embodiment of the present invention, a barrier layer 12 is provided on one surface of the base material 11, and a hot melt adhesive layer 13 is further provided on the barrier layer 12.

[0012] Figure 2 is a cross-sectional view showing the configuration of an adhesive sheet according to a second embodiment of the present invention. In the adhesive sheet 1b according to the second embodiment of the present invention, a barrier layer 12 is provided on one surface of the base material 11, a hot melt adhesive layer 13 is provided on the barrier layer 12, and a release liner 14 is provided on the hot melt adhesive layer 13. The following describes each layer that constitutes the adhesive sheet of the present invention.

[0013] <Barrier layer> The barrier layer comprises at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins, and may optionally contain other resins, crosslinking agents, other additives, etc.

[0014] There are no particular restrictions on the thickness of the barrier layer, but from the viewpoint of interlayer adhesion between the barrier layer and the hot melt adhesive layer, it is preferably 0.01 μm or more, more preferably 0.2 μm or more, particularly preferably 0.3 μm or more, and preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 2 μm or less. The thickness of the barrier layer is specifically a value measured and calculated based on the method described in the examples below.

[0015] There are no particular restrictions on the total content of polyester resin, polyurethane resin, and polyolefin resin in the barrier layer, but it is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass. Here, the content refers to the content of only one type selected from the group consisting of polyester resin, polyurethane resin, and polyolefin resin, or the total content of two or more types selected from the group consisting of polyester resin, polyurethane resin, and polyolefin resin.

[0016] There are no particular restrictions on the method for forming the barrier layer, but in one embodiment of the present invention, from the viewpoint of suppressing the migration of softener when the thickness of the barrier layer is thin, it is preferable to include a step of applying a solution (coating liquid) obtained by dissolving at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins (hereinafter, polyester resins, polyurethane resins, and polyolefin resins are also simply referred to as "resins") in a solvent to the substrate. That is, it is preferable that the barrier layer is a layer formed by applying a solution (coating liquid) obtained by dissolving polyester resin in a solvent to the substrate.

[0017] Examples of solvents used in the barrier layer formation method include methanol, ethanol, propanol, butanol, isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, toluene, dimethylacetamide, ethylene glycol, ethylene glycol mono-n-propyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate. These may be used individually or in combination of two or more. Among these, methyl ethyl ketone and toluene are preferred from the viewpoint of obtaining a homogeneous solution.

[0018] In another embodiment of the present invention concerning a method for forming a barrier layer, from the viewpoint of environmental impact and safety during coating, such as preventing ignition accidents due to static electricity, the method may include a step of applying an aqueous resin dispersion (coating liquid) obtained by dispersing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins in water to a substrate, or a step of applying an aqueous solution (coating liquid) containing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins to a substrate. Among these, it is preferable to include a step of applying an aqueous resin dispersion obtained by dispersing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins in water to a substrate. That is, it is preferable that the barrier layer is a layer formed by applying an aqueous resin dispersion obtained by dispersing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins in water to a substrate. Note that an aqueous resin dispersion refers to one that contains water as the main component and contains 50% by mass or more of water. The aqueous resin dispersion, obtained by dispersing at least one resin selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins in water, may contain the above-mentioned solvent, and the above-mentioned solvent may be used alone or in combination of two or more types.

[0019] (Polyester resin) The polyester resin included in the barrier layer is not particularly limited as long as it is at least one of polyester resin and modified polyester resin. However, it is usually a resin having ester bonds in its main chain, and from the viewpoint of suppressing the migration of softeners, it is preferable to include a modified polyester resin, and more preferably a modified polyester resin.

[0020] There are no particular restrictions on the glass transition temperature of the polyester resin, but in one embodiment of the present invention, from the viewpoint of suppressing the migration of the softener, it is preferably 40°C or higher, more preferably 55°C or higher, even more preferably 70°C or higher, and particularly preferably 80°C or higher, and from the viewpoint of film formation, it is preferably 130°C or lower, more preferably 95°C or lower, even more preferably 90°C or lower, and particularly preferably 85°C or lower. In another embodiment of the present invention, from the viewpoint of suppressing the migration of the softener, it is preferably 20°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, and from the viewpoint of film formation, it is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. If the glass transition temperature is below 40°C, the effect of suppressing the migration of the softener may not be obtained, and if it is above 130°C, defects may occur and it may be difficult to form a coating film. The glass transition temperature is a value measured and calculated based on the method described in the examples below.

[0021] There are no particular restrictions on the hydroxyl value of the polyester resin, but it is preferably 0.5 KOH mg / g or more, more preferably 1 KOH mg / g or more, particularly preferably 2 KOH mg / g or more, and preferably 10 KOH mg / g or less, more preferably 9 KOH mg / g or less, and particularly preferably 8 KOH mg / g or less. The hydroxyl value of the polyester resin is a value measured and calculated based on the method described in the examples below.

[0022] There are no particular restrictions on the acid value of the polyester resin, but in one embodiment of the present invention, it is preferably 10KOHmg / g or less, more preferably 2KOHmg / g or less, and particularly preferably 1KOHmg / g or less. In another embodiment of the present invention, it is preferably 30KOHmg / g or more, more preferably 35KOHmg / g or more, particularly preferably 40KOHmg / g or more, and preferably 80KOHmg / g or less, more preferably 75KOHmg / g or less, and particularly preferably 70KOHmg / g or less. The acid value of the polyester resin is a value measured and calculated based on the method described in the examples below.

[0023] There are no particular restrictions on the number average molecular weight Mn of the polyester resin, but in one embodiment of the present invention, it is preferably 10,000 or more, more preferably 20,000 or more, and preferably 100,000 or less, and more preferably 50,000 or less. In another embodiment of the present invention, it is preferably 1,000 or more, more preferably 2,000 or more, and preferably 10,000 or less, and more preferably 5,000 or less.

[0024] [Polyester resin] Polyester resin is a copolymer obtained by polycondensation reaction between an acid component and a diol component or a polyol component. The aforementioned polycondensation reaction is carried out by general polyesterization reactions such as direct esterification and transesterification. These polyester resins may be used individually or in combination of two or more types.

[0025] Examples of the above acid components include aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, sulfoterephthalic acid, isophthalic acid, phthalic anhydride, α-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfisoisophthalic acid, 5-potassium sulfisoisophthalic acid, or their anhydrides or esters; aliphatic dicarboxylic acids such as pimelic acid, suberic acid, azelaic acid, oxalic acid, sebacic acid, succinic acid, adipic acid, undecylenic acid, dodecanedicarboxylic acid, or their anhydrides or esters; and alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, or their anhydrides or esters. These may be used individually or in combination of two or more.

[0026] Examples of the above-mentioned diol or polyol components include aliphatic glycols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methylpentanediol, 2,2,3-trimethylpentanediol, diethylene glycol, triethylene glycol, and dipropylene glycol; alicyclic glycols such as 1,2-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; and aromatic glycols such as p-xylene glycol and bisphenol A. These may be used individually or in combination of two or more.

[0027] The polyester resin may have reactive functional groups. Specific examples of reactive functional groups include, for instance, hydroxyl groups, carboxyl groups, and amino groups. Furthermore, the above-mentioned reactive functional groups may be those that participate in the polymerization reaction (i.e., those that participate in the formation of the main chain), or they may be added additionally. Polyester resins may have polyol-based structural units that have hydroxyl groups, or carboxylic acid-based structural units that have carboxylic acids, and these residual hydroxyl groups or residual carboxylic acids can become the above-mentioned reactive functional groups.

[0028] Furthermore, the polyester resin may have an active energy ray polymerizable functional group. A polyester resin having such a structure can be produced, for example, by coexisting a compound having an active energy ray polymerizable functional group with monomers and / or oligomers (hereinafter also referred to as "monomers, etc.") in the step of carrying out a polymerization reaction to form a polyester resin, and causing the reaction between this compound and the monomers, etc. to occur together with the polymerization reaction of the monomers, etc., thereby incorporating this compound into the backbone of the polyester resin. In this specification, "active energy rays" refers to electromagnetic waves or charged particle beams that have energy quanta, that is, active light such as ultraviolet rays or electron beams.

[0029] A suitable example of a commercially available polyester resin is "Nichigo Polyester TP-220" (compound name: saturated copolymer polyester) manufactured by Mitsubishi Chemical Corporation.

[0030] [Modified polyester resin] The modified polyester resin is not particularly limited as long as it is a modified version of the above-mentioned polyester resin, and examples include urethane-modified polyester resin, acrylic-modified polyester resin, and silicone-modified polyester resin. These may be used individually or in combination of two or more. Among these, urethane-modified polyester resin is preferred from the viewpoint of suppressing the migration of the softening agent.

[0031] Examples of urethane-modified polyester resins include those having urethane bonds in addition to the polyester resin. For example, urethane-modified polyester resins can be obtained by reacting a polyester resin having two or more functional groups such as hydroxyl groups in one molecule with a polyisocyanate compound. Specific examples of urethane-modified polyester resins include, for example, polymers (polyester urethanes) obtained by reacting various polyisocyanate compounds with a polyester polyol having a hydroxyl group at the end of a copolymer obtained by polycondensation reaction of the above-mentioned acid component with a diol component or polyol component.

[0032] For use in urethane modification of polyester resins, polyisocyanate compounds having two or more isocyanate groups per molecule are preferred. Examples of polyisocyanate compounds having two or more isocyanate groups per molecule include diisocyanate compounds, triisocyanate compounds, tetraisocyanate compounds, pentaisocyanate compounds, and hexisocyanate compounds. More specifically, examples include aromatic polyisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; alicyclic isocyanate compounds such as dicyclohexylmethane-4,4-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and hydrogenated xylylene diisocyanate; and aliphatic isocyanate compounds such as pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. These may be used individually or in combination of two or more types. Furthermore, modified forms such as biuret and isocyanurate compounds of these isocyanate compounds, as well as adduct compounds which are reaction products of these isocyanate compounds with non-aromatic low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, trimethylolpropane, and castor oil, can also be used.

[0033] Preferably, the urethane-modified polyester resin is a urethane-modified polyester resin having the basic structure of an aromatic polyester. The basic structure of an aromatic polyester is one in which the polyester structure of the main chain has repeating units derived from an aromatic compound, and is obtained, for example, when one or both of the dicarboxylic acid and glycol compounds of some or all of the copolymerization raw materials are aromatic compounds.

[0034] A suitable example of a commercially available urethane-modified polyester resin is "Byron UR4800" (compound name: saturated copolymer polyester urethane) manufactured by Toyobo Co., Ltd.

[0035] [Polyurethane resin] The polyurethane resin contained in the barrier layer is not particularly limited, but is usually a resin obtained by reacting a polyisocyanate component with a polyol component, and is chain-extended in the presence of a chain-extending agent, which is a low molecular weight compound having two or more active hydrogens, such as a diol or diamine, if necessary.

[0036] There are no particular restrictions on the glass transition temperature of polyurethane resins, but from the viewpoint of suppressing the migration of softeners, it is preferably 40°C or higher, more preferably 55°C or higher, even more preferably 70°C or higher, and particularly preferably 80°C or higher. From the viewpoint of film formation, it is preferably 130°C or lower, more preferably 95°C or lower, and particularly preferably 90°C or lower. If the glass transition temperature is below 40°C, the effect of suppressing the migration of softeners may not be obtained, and if it is above 130°C, defects may occur and it may become difficult to form a coating film. The glass transition temperature is a value measured and calculated based on the method described in the examples below.

[0037] There are no particular restrictions on the acid value of the polyurethane resin, but it is preferably 1 KOH mg / g or more, more preferably 5 KOH mg / g or more, particularly preferably 8 KOH mg / g or more, and preferably 50 KOH mg / g or less, more preferably 40 KOH mg / g or less, particularly preferably 30 KOH mg / g or less. The acid value of the polyurethane resin is a value measured and calculated based on the method described in the examples below.

[0038] There are no particular restrictions on the number-average molecular weight (Mn) of the polyurethane resin, but it is preferably 1000 or more, more preferably 2000 or more, and preferably 1,000,000 or less, and more preferably 500,000 or less.

[0039] There are no particular restrictions on the polyisocyanate component, but aliphatic polyisocyanates are preferred from the viewpoint of suppressing the migration of the softening agent. Examples of aliphatic polyisocyanates include chain-type aliphatic polyisocyanates and cyclic aliphatic polyisocyanates.

[0040] Examples of chain-type aliphatic polyisocyanates include trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl capeate. Among these, HDI is preferred.

[0041] Examples of cyclic aliphatic polyisocyanates include 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), methylenebis(cyclohexyl isocyanate) (4,4'-, 2,4'- or 2,2'-methylenebis(cyclohexyl isocyanate), their trans,trans-, trans,Cis-, Cis,Cis-, or mixtures thereof) (H 12 Examples include MDI, methylcyclohexane diisocyanate (methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), norbornane diisocyanate (various isomers or mixtures thereof) (NBDI), and 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI) (also known as hydrogenated xylylene diisocyanate). Among these, IPDI is particularly preferred.

[0042] Examples of polyol components include polyether polyols, polyester polyols, and polycarbonate polyols.

[0043] Examples of polyether polyols include those obtained by ring-opening homopolymerization or ring-opening copolymerization of alkylene oxides (e.g., C2-C5 alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, 3-methyltetrahydrofuran, and oxetane compounds) using a low molecular weight polyol as an initiator. Specifically, examples include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene-propylene copolymer, and polyoxytetramethylene glycol (polytetramethylene ether glycol).

[0044] Examples of low molecular weight polyols include low molecular weight polyols with a molecular weight of 60 to 400 having two or more hydroxyl groups, such as ethylene glycol, propanediol, 1,4-butylene glycol (1,4-butanediol), 1,6-hexanediol, 1,2-butylene glycol, 1,3-butylene glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, alkane (7 to 22 carbon atoms) diol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanedimethanol, alkane-1,2-diol (17 to 20 carbon atoms), 1,4-dihydroxy-2-butene, 2,6-dimethyl-1-octen-3,8-diol, bishydroxyethoxybenzene, xylene glycol, bishydroxyethoxybenzene Examples include low molecular weight diols such as ethylene terephthalate; low molecular weight triols such as glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolpropane, 2,2-bis(hydroxymethyl)-3-butanol, and other aliphatic triols (8 to 24 carbon atoms); and low molecular weight polyols having four or more hydroxyl groups, such as tetramethylolmethane, D-sorbitol, xylitol, D-mannitol, and D-mannitol.

[0045] Polyester polyols can be obtained by known esterification reactions, namely condensation reactions between polyhydric alcohols and polybasic acids, or transesterification reactions between polyhydric alcohols and alkyl esters of polybasic acids. Examples of polybasic acids or their alkyl esters include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, azelaic acid, dimer acid, and dodecanedioic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid and tetrahydrophthalic acid; aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid, or their dialkyl esters (e.g., alkyl esters with 1-6 carbon atoms), their acid anhydrides, and mixtures thereof. It can be done.

[0046] [Polyolefin resins] The polyolefin resin included in the barrier layer is not particularly limited, but is usually a homopolymer of an olefin compound or a copolymer with other compounds.

[0047] There are no particular restrictions on the softening point of the polyolefin resin contained in the barrier layer, but from the viewpoint of suppressing the migration of the softener, it is preferably 0°C or higher, more preferably 20°C or higher, even more preferably 25°C or higher, and particularly preferably 30°C or higher. From the viewpoint of film formation, it is preferably 100°C or lower, more preferably 60°C or lower, even more preferably 55°C or lower, and particularly preferably 50°C or lower. If the softening point is below 0°C, the effect of suppressing the migration of the softener may not be obtained, and if it is above 100°C, defects may occur and it may become difficult to form a coating film. The softening point is a value measured and calculated based on the method described in the examples below.

[0048] There are no particular restrictions on the number-average molecular weight (Mn) of the polyolefin resin, but it is preferably 1000 or more, more preferably 2000 or more, and preferably 1,000,000 or less, and more preferably 500,000 or less.

[0049] Examples of olefin compound homopolymers include α-olefins with 2 to 20 carbon atoms, such as polyethylene (low-density polyethylene, medium-density polyethylene, high-density polyethylene, or linear low-density polyethylene), polypropylene, polyisobutylene, poly(1-butene), poly(1-pentene), and poly(1-hexene).

[0050] Examples of copolymers of olefin compounds include ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-octene copolymer, and ethylene-1-hexene copolymer.

[0051] Furthermore, polyolefin resins with introduced polar groups can also be used as polyolefin resins. Specific examples of polyolefin resins with introduced polar groups include acid-modified polyolefins such as maleic anhydride-modified polyethylene, maleic acid-modified polyethylene, acrylic acid-modified polyethylene, maleic anhydride-modified polypropylene, maleic acid-modified ethylene-propylene copolymer, and acrylic acid-modified polypropylene; ethylene-vinyl chloride copolymer, ethylene-vinylidene chloride copolymer, ethylene-acrylonitrile copolymer, ethylene-methacrylonitrile copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylamide copolymer, ethylene-methacrylamide copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-maleic acid copolymer, ethylene-methyl (meth)acrylate copolymer, and ethylene-ethyl (meth)acrylate copolymer. Examples include ethylene or α-olefin-vinyl monomer copolymers such as ethylene-isopropyl(meth)acrylate copolymer, ethylene-(meth)acrylate copolymer, ethylene-isobutyl(meth)acrylate copolymer, ethylene-2-ethylhexyl(meth)acrylate copolymer, ethylene-maleic anhydride copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer, ethylene-(meth)acrylic acid metal salt copolymer, ethylene-vinyl acetate copolymer or its saponified product, ethylene-vinyl propionate copolymer, ethylene-glycidyl(meth)acrylate copolymer, ethylene-ethyl acrylate-glycidyl methacrylate copolymer, and ethylene-vinyl acetate-glycidyl methacrylate copolymer; and chlorinated polyolefins such as chlorinated polypropylene and chlorinated polyethylene.

[0052] (Other resins) The barrier layer may contain resins other than polyester resins, polyurethane resins, and polyolefin resins, as long as the effects of the present invention are not impaired. Other resins that can be used include known resins used for forming barrier layers, depending on the rubber, resin, etc. used to form the hot-melt adhesive layer provided on top of the barrier layer, as described later. Other specific examples of resins include thermoplastic resins such as acrylic resins, acrylic-modified polyolefin resins, chlorinated polyolefin resins, vinyl chloride-vinyl acetate copolymers, polyamide resins, and rubber resins; and thermosetting resins such as epoxy resins. These may be used individually or in combination of two or more types.

[0053] There are no particular restrictions on the content of other resins in the barrier layer, but it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less, and may not be included at all.

[0054] (Crosslinking agent) The barrier layer may contain a crosslinking agent, as long as it does not impair the effects of the present invention. Examples of crosslinking agents include polyisocyanate compounds having two or more isocyanate groups per molecule, more specifically, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; alicyclic isocyanate compounds such as dicyclohexylmethane-4,4'-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and hydrogenated xylylene diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. These may be used individually or in combination of two or more.

[0055] Furthermore, as crosslinking agents, modified forms such as biuret and isocyanurate forms of the above-mentioned polyisocyanate compounds, or adduct forms which are reaction products of these polyisocyanate compounds with non-aromatic low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, trimethylolpropane, and castor oil, can also be used.

[0056] A suitable example of a commercially available crosslinking agent is "Coronate L" (an isocyanate compound) manufactured by Tosoh Corporation.

[0057] There are no particular restrictions on the crosslinking agent content in the barrier layer, but it is preferably 15% by mass or less, more preferably 10% by mass or less, and most preferably 8% by mass or less.

[0058] (Other additives) The barrier layer may contain additives other than the crosslinking agent, as long as they do not impair the effects of the present invention. Other additives can be appropriately selected depending on the application of the barrier layer, and include, for example, fillers, pigments, colorants, metal powders, conductive materials, plasticizers, solvents, surfactants, dispersants, neutralizing agents, thickeners, wetting agents, defoamers, lubricants, antistatic agents, preservatives, antioxidants, and UV absorbers. These may be used individually or in combination of two or more.

[0059] There are no particular restrictions on the content of other additives in the barrier layer, but it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and most preferably 1% by mass or less.

[0060] <Base material> The base material can be appropriately selected depending on the application of the adhesive sheet, and examples include stretched polypropylene resin film, synthetic paper or other resin films, and paper substrates. From the viewpoint of the effects of the present invention, a substrate containing at least one of paper and a polyolefin resin is preferred. Examples of polyolefin resins include polyethylene, polypropylene, and ethylene-propylene copolymer.

[0061] The thickness of the substrate is set appropriately depending on the application of the adhesive sheet, but from the viewpoint of handling and economy, it is preferably 5 to 250 μm, more preferably 15 to 200 μm, and particularly preferably 25 to 150 μm. The thickness of the substrate is specifically measured and calculated using the same method as the thickness of the barrier layer.

[0062] Furthermore, when using a resin film or laminated paper as the substrate, surface treatments such as oxidation or embossing may be applied to the surface of the resin film or laminated paper to further improve interlayer adhesion between the substrate and the barrier layer. Oxidation methods include, for example, corona discharge treatment, plasma treatment, chromate oxidation (wet method), flame treatment, hot air treatment, and ozone / ultraviolet irradiation treatment. Other methods for creating uneven surfaces include, for example, sandblasting and solvent treatment. These surface treatments are selected appropriately depending on the type of substrate, but corona discharge treatment is preferred from the viewpoint of further improving interlayer adhesion between the substrate and the barrier layer and from the viewpoint of ease of operation.

[0063] (Resin film) Examples of resins included in the resin film include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; urethane resins such as polyurethane and acrylic-modified polyurethane; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polystyrene resin; acrylonitrile-butadiene-styrene (ABS) resin; cellulose triacetate resin; polycarbonate resin; acetate resin; polyamide resin; and polyimide resin. These may be used individually or in combination of two or more. Synthetic paper may also be used as the resin film.

[0064] There are no particular restrictions on the resin content in the resin film, but it is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass.

[0065] In addition to the resin mentioned above, the resin film may further contain additives such as fillers, UV absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, and colorants.

[0066] The resin film may be a laminate formed by stacking multiple resin films, or it may be a foam.

[0067] (Paper base material) Examples of paper included in the paper substrate include tissue paper, medium-grade paper, fine-grade paper, impregnated paper, coated paper, art paper, sulfuric acid paper, and glassine paper. These may be used individually or in combination of two or more types.

[0068] There are no particular restrictions on the paper content in the paper substrate, but it is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass.

[0069] There are no particular restrictions on the density of the paper in the paper substrate, but it is preferably 0.90 g / cm³. 3 More preferably 0.95 g / cm³ 3 More preferably 0.98 cm 3 The above is preferable, and preferably 1.5 g / cm³. 3 More preferably, 1.3 g / cm³ 3 More preferably, 1.2 g / cm³ 3 The following applies:

[0070] <Hot melt adhesive layer> The hot-melt adhesive layer is applied by adding a softening agent to a thermoplastic resin such as rubber, acrylic, or olefin, heating and melting it. It may also contain tackifiers, other additives, etc., as needed. In one embodiment of the present invention, the hot melt adhesive layer is preferably a layer containing rubber and a tackifier. The thickness of the hot melt adhesive layer is not particularly limited, but is preferably 1 to 200 μm, more preferably 5 to 150 μm, and most preferably 10 to 100 μm. The thickness of the hot melt adhesive layer is specifically measured and calculated using the same method as the thickness of the barrier layer.

[0071] (rubber) Examples of rubbers that may be included in the hot melt adhesive layer include natural rubbers such as RSS-No.1~4, SMR-5L, SMR-20, and CV-60; and synthetic rubbers such as styrene-isoprene-styrene block copolymer (SIS) rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, and nitrile rubber. These may be used individually or in combination of two or more types. Among these, styrene-isoprene-styrene block copolymer (SIS) rubber is preferred. Furthermore, since most rubbers have a large molecular weight, their molecular weight is mechanically reduced using mixing rolls, Banbury kneaders, and kneaders to improve their initial tackiness and coating properties.

[0072] There are no particular restrictions on the weight-average molecular weight of the rubber, but from the viewpoint of the application of the hot-melt adhesive and the adhesive properties of the adhesive sheet, it is preferably between 100,000 and 500,000. If the weight-average molecular weight of the rubber is above the lower limit, sufficient cohesive force can be obtained, and if it is below the upper limit, the viscosity of the hot-melt adhesive can be reduced and the coating properties can be improved.

[0073] (Softener) The softener contained in the hot melt adhesive layer reduces the viscosity of the hot melt adhesive and improves its applicability. Examples include petroleum-based softeners such as process oil and extender oil; vegetable oil-based softeners such as tall oil; and synthetic plasticizers such as dibasic acid ester plasticizers. These may be used individually or in combination of two or more. Among these, process oils such as paraffinic process oils, naphthenic process oils, aromatic process oils, and other known process oils are preferred. There are no particular restrictions on the content of the softener in the hot melt adhesive layer, but it is preferably 20 to 200 parts by mass per 100 parts by mass of rubber.

[0074] (Adhesive-forming resin) The tackifier (tackifying resin) that may be included in the hot melt adhesive layer plays a role in enhancing initial tack and adhesive strength. Examples of tackifying resins include rosin resins, ester compounds of rosin resins with pentaerythritol, terpene resins including polymers of terpenes such as α-pinene and β-pinene and copolymers thereof; terpene modified products such as terpene phenol resins; petroleum resins such as aromatic hydrocarbon resins and aliphatic hydrocarbon resins (e.g., aliphatic / aromatic copolymer petroleum resins) and their hydrides; and phenol resins such as coumarone indene resins and alkylphenol acetylene resins. These may be used individually or in combination of two or more.

[0075] There are no particular restrictions on the content of the tackifying resin, but it is preferably 20 to 200 parts by mass per 100 parts by mass of rubber. If the content of the tackifying resin is above the lower limit, good initial adhesion can be obtained, and if it is below the upper limit, the desired cohesive force can be obtained.

[0076] (Other additives) Other additives that may be included in the hot melt adhesive layer include, for example, fillers such as calcium carbonate and clay; pigments; and antioxidants. These may be used individually or in combination of two or more.

[0077] Examples of equipment for mixing the above components include Banbury kneaders, kneaders, and twin-screw extruders. These may be used individually or in combination of two or more. If it is necessary to reduce the molecular weight of the rubber, the rubber may be mixed with a softening agent, tackifying resin, and other additives after the molecular weight reduction, or it may be mixed at the same time as the molecular weight reduction of the rubber. There are no particular restrictions on the mixing temperature, but from the viewpoint of uniformity, it is preferably above the softening point of the tackifying resin, and from the viewpoint of preventing deterioration of the rubber, it is preferably 200°C or lower.

[0078] <Removable Liner> The release liner is typically formed on the hot-melt adhesive layer opposite the barrier layer. In one embodiment of the present invention, the adhesive sheet preferably further has a release liner on the hot melt adhesive layer opposite to the barrier layer. Examples of release liners include release sheets with double-sided release treatment and release sheets with single-sided release treatment. Examples of release treatments include applying a release agent to the surface of the substrate for the release liner. Examples of substrates for release liners include resin films, paper substrates, laminated paper, and synthetic paper, which can be used as substrates for adhesive sheets. These may be used individually or in combination of two or more types. Examples of release agents include olefin resins, isoprene resins, butadiene resins, silicone resins, long-chain alkyl resins, alkyd resins, and fluoropolymer resins. These may be used individually or in combination of two or more.

[0079] There are no particular restrictions on the thickness of the release liner, but it is preferably 10 to 200 μm, and more preferably 25 to 150 μm. The thickness of the release liner is specifically measured and calculated using the same method as the thickness of the barrier layer.

[0080] <Print coating layer> The printed coating layer is typically formed on the substrate opposite the barrier layer. The resin material for the printing coating layer is not particularly limited as long as it has good adhesion to the substrate and can form a printing coating layer with good adhesion to the printing ink. Examples include acrylic resins, styrene resins, polyester urethane resins, polyester resins, polyurethane resins, polyol resins, polyvinyl alcohol, polyvinylpyrrolidone, cellulose derivatives, acetate derivatives, polyvinyl chloride resins, and polyimide resins. These may be used individually or in combination of two or more. Among these, polyester urethane resin is preferred. The polyester urethane resin may be polymerized using crosslinking agents or crosslinking accelerators as appropriate.

[0081] When the substrate on which the printed coating layer is formed is a resin film such as synthetic paper, there are no particular restrictions on the resin material content in the printed coating layer, but it is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass.

[0082] Examples of additives that can be added to the printed coating layer include pigments, colorants, metal powders, conductive materials, plasticizers, solvents, surfactants, dispersants, neutralizing agents, thickeners, wetting agents, defoamers, lubricants, antistatic agents, crosslinking agents, preservatives, antioxidants, and UV absorbers. These may be used individually or in combination of two or more.

[0083] There are no particular restrictions on the content of additives in the printed coating layer, but it is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. Furthermore, when the substrate on which the print coating layer is formed is a paper substrate or a paper-containing substrate such as laminated paper, the amount of additives (e.g., inorganic materials) in the print coating layer will be higher and the amount of resin material in the print coating layer will be lower than when the substrate is a resin film such as synthetic paper.

[0084] There are no particular restrictions on the thickness of the printed coating layer, but it is preferably 10 to 600 nm, and more preferably 30 to 200 nm. The thickness of the printed coating layer is specifically measured and calculated using the same method as the thickness of the barrier layer.

[0085] [Method for manufacturing adhesive sheets] There are no particular restrictions on the method for manufacturing the adhesive sheet, but preferred examples are shown below. For example, the adhesive sheet 1a in Figure 1 can be manufactured by applying a material capable of forming a barrier layer, which includes at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins, onto a substrate 11 using a known coating method, drying it to form a barrier layer 12, and then applying the hot melt adhesive described above onto the barrier layer 12 using a known coating method to form a hot melt adhesive layer 13. Furthermore, by laminating a release liner 14 onto the hot melt adhesive layer 13 of the adhesive sheet 1a shown in Figure 1, which was manufactured using the method described above, the adhesive sheet 1b shown in Figure 2 can be manufactured. Furthermore, the adhesive sheet 1b in Figure 2 can also be manufactured by bonding a hot-melt adhesive layer 13 formed on a release liner 14 using the method described above with a barrier layer 12 formed on a substrate 11 using the method described above. Alternatively, a printed coating layer (not shown) may be formed on the substrate 11 of the adhesive sheet 1a in Figure 1 or the adhesive sheet 1b in Figure 2, which is manufactured by the method described above.

[0086] In one embodiment of the present invention, the material capable of forming a barrier layer is preferably applied to a substrate in the form of a solution by adding a solvent, from the viewpoint of improving coatability and work efficiency. The solvent is not particularly limited, but an organic solvent is preferred because the material that can form the barrier layer includes at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins. Examples of solvents include methanol, ethanol, propanol, butanol, isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, toluene, dimethylacetamide, ethylene glycol, ethylene glycol mono-n-propyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate. These may be used individually or in combination of two or more. Among these, methyl ethyl ketone and toluene are preferred from the viewpoint of obtaining a homogeneous solution.

[0087] In another embodiment of the present invention, the material capable of forming a barrier layer may be applied to the substrate in the form of at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins dispersed in water (aqueous resin dispersion), or in the form of at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins dissolved in water (aqueous solution), from the viewpoint of environmental impact and safety during coating, such as preventing ignition accidents due to static electricity. Among these, it is preferable that the resin be applied to the substrate in the form of a dispersion in water. The aqueous resin dispersion and aqueous solution may contain the above-mentioned solvent, and the solvent may be used alone or in combination of two or more types. It is preferable that the aqueous resin dispersion and aqueous solution do not contain any solvent other than water.

[0088] Furthermore, for materials that can form a printed coating layer, it is preferable to add a solvent to form a solution and apply it to the substrate, from the viewpoint of improving coatability and work efficiency. The solvent is not particularly limited and can be appropriately selected depending on the type of material that can form the printed coating layer described above.

[0089] Examples of the method for applying a material capable of forming a barrier layer and a material capable of forming a printing coat layer include, for example, spin coating method, spray coating method, bar coating method, knife coating method, air knife coating method, roll knife coating method, roll coating method, blade coating method, die coating method, gravure coating method, lip coating method, curtain coating method, and the like. Examples of the method for applying a material capable of forming a hot melt adhesive layer include, for example, spray coating method, bar coating method, knife coating method, air knife coating method, roll knife coating method, roll coating method, blade coating method, die coating method, gravure coating method, lip coating method, curtain coating method, and the like. In addition, the drying temperature and drying time of the coating film formed after applying the barrier layer and the printing coat layer are not particularly limited and can be set as appropriate.

Examples

[0090] The present invention will be specifically described by the following examples, but the present invention is not limited to the following examples. In addition, the following various physical property values are the values measured by the following method.

[0091] (1) Color change degree (brightness index ratio) For the paper substrate surface of each adhesive sheet sample obtained in Examples 1 to 3 and Comparative Examples 1 to 5 (using a paper substrate (product name: OK Kintou single-sided, manufactured by Oji Paper Co., Ltd., thickness: 75 μm) as the substrate), the brightness index (L * ) was measured (designated as “L * (initial-a)”), and further, the brightness index (L * ) after storing for 10 days in an environment at a temperature of 60 °C was measured (designated as “L * (10D-a)”). The brightness index ratio “L * (10D-a) / L * (initial)” was calculated. The results are shown in Table 1. In addition, the brightness index (L * ) was measured based on JIS K5600-4-5:1999 (using a spectrocolorimeter SE6000 manufactured by Nippon Denshoku Industries Co., Ltd. as the measuring instrument). Here, "Brightness Index (L * The "brightness index ratio" represents the degree of brightness; a higher number indicates a brighter color, while a lower number indicates a darker color. Furthermore, a "brightness index ratio" closer to 100 is preferable, as it indicates less discoloration. (2) Degree of discoloration (color difference) Regarding the paper substrate surface of each adhesive sheet sample obtained in Examples 16-23 and Comparative Examples 21 and 22 (in Examples 16-20 and Comparative Example 21, coated paper (thickness: 89 μm) was used as the substrate, and in Examples 21-23 and Comparative Example 22, high-quality paper (thickness: 73 μm) was used as the substrate), L * a * b * L of the color system * value, a * Value and b * Measure the value ("L * (initial-b), a * (initial-b), b * (initial-b) and then L after being stored for 7 days in a 70°C environment. * a * b * L of the color system * value, a * Value and b * Measure the value ("L * (10D-b), a * (10D-b), b * (10D-b)) The degree of discoloration ΔE (color difference) was calculated using the following formula. The results are shown in Tables 6 and 7. ΔE * = [(L * (initial-b)-L * (10D-b)) 2 +(a * (initial-b)-a * (10D-b)) 2 +(b * (initial-b)-b * (10D-b)) 2 ] 1 / 2 Note L * value, a * Value and b *The value is L, which was standardized by the International Commission on Illumination (CIE) in 1976. * a * b * It is based on a color system. * a * b * The color system used is as defined in JIS Z8781-4:2013. Measurements were taken using a spectrophotometer SE6000 manufactured by Nippon Denshoku Industries Ltd., measuring reflected light from the substrate side (opposite the release liner side). Here, "Color change degree ΔE * The value "ΔE" represents the degree of discoloration; a larger value indicates a greater change in color tone, while a smaller value indicates a smaller change in color tone. * The closer the value is to 0, the less discoloration is observed, which is preferable. (3) Degree of deformation (height difference from the standard (mm)) The degree of deformation was measured for each adhesive sheet sample obtained in Examples 4-6 and 24-30, and Comparative Examples 6-10 and 23 (using synthetic paper (product name: Yupo, manufactured by Yupo Corporation, thickness: 80 μm) as the base material). The degree of deformation in Examples 4-6 and Comparative Examples 6-10 was calculated by placing an adhesive sheet sample (square: 100mm x 100mm) with the release liner removed onto a 20mm diameter cylinder with the adhesive layer facing upwards, leaving it undisturbed at 23°C for 7 days, and then measuring the height difference of the four corners of the square relative to a reference point and averaging the results. The results are shown in Table 2. The degree of deformation in Examples 24-30 and Comparative Example 23 was calculated by placing an adhesive sheet sample (square: 50mm x 50mm) with the release liner removed, with the adhesive layer facing upwards, and leaving it at 50°C for 1 hour. The height difference between the four corners of the square and a reference point was then measured and averaged. The results are shown in Table 8. Here, the closer the "height difference relative to the standard (mm)" is to 0, the smaller the degree of deformation, which is preferable. (4) Degree of deformation (elongation (μm)) The elongation was measured for each adhesive sheet sample obtained in Examples 7-15 and Comparative Examples 11-25 (using stretched polypropylene resin film (product name: Alphan SY101, manufactured by Oji F-Tex, thickness: 50 μm) as the base material). Furthermore, elongation was measured by leaving an adhesive sheet sample (square: 100mm x 100mm) undisturbed at 60°C for 7 days, and then measuring the length (elongation (μm)) of the substrate protruding from the release liner. The results are shown in Tables 3-5. Here, the smaller the elongation, the smaller the degree of deformation, which is preferable. (5) Thickness of each layer (barrier layer, substrate, hot melt adhesive layer, release liner) The thickness of each layer (barrier layer, substrate, hot melt adhesive layer, and release liner) was measured using a constant pressure thickness gauge manufactured by Teclock Corporation (model number: "PG-02J", compliant with standards: JIS K6783:1994, JIS Z1702:1994, and JIS Z1709:1995). (6) Glass transition temperature (Tg) of resin The glass transition temperature (°C) of the resin used to form the barrier layer was measured in accordance with JIS K 7121 using a differential scanning calorimeter (manufactured by T.A. Instruments Japan Co., Ltd., product name "DSC Q2000") at a heating rate of 20°C / min. The results are shown in Tables 1-5. (7) Softening point The softening point (°C) of the resin used to form the barrier layer was measured based on the softening point test method (ring-ball method) specified in JIS K5601-2-2:1999. (8) Hydroxy value of resin The hydroxyl value (KOH mg / g) of the resin used to form the barrier layer was measured in accordance with JIS K 0070:1992. (9) Acid value of resin The acid value (KOH mg / g) of the resin used to form the barrier layer was measured in accordance with JIS K 0070:1992.

[0092] The resins and crosslinking agents used in this example and comparative example are as follows. (1) "Polyester resin 1" (glass transition temperature: 67°C, hydroxyl value: 6KOH mg / g, acid value: less than 2KOH mg / g) (2) "Urethane-modified polyester resin" (glass transition temperature: 83°C, hydroxyl value: 2-3 KOH mg / g, acid value: less than 1 KOH mg / g) (3) "Vinyl chloride-vinyl acetate copolymer" (glass transition temperature: 73°C) (4) "Acrylic resin (ethyl acrylate-methyl methacrylate-butyl methacrylate copolymer)" (glass transition temperature: 40°C) (5) "Polyvinylpyrrolidone (PVP)" (glass transition temperature: 86°C) (6) "Polyester resin 2" (glass transition temperature: 46°C, hydroxyl value: 5KOH mg / g, acid value: 50KOH mg / g) (7) "Polyurethane resin" (glass transition temperature: 85°C, acid value: 18KOH mg / g) (8) "Polyolefin resin" (softening point: 40℃) (9) "Crosslinking agent: Isocyanate compound"

[0093] [Example 1] <Preparation of barrier layer forming materials> A barrier layer-forming material (coating solution) was prepared by mixing a polyester resin (glass transition temperature: 67°C, hydroxyl value: 6KOH mg / g, acid value: less than 2KOH mg / g) with toluene and methyl ethyl ketone as solvents, resulting in a solid content concentration of 10% by mass.

[0094] <Preparation of hot melt adhesive> A tack composition was prepared by uniformly mixing 100 parts of styrene-isoprene-styrene block copolymer (SIS) rubber (styrene content: 15% by mass, diblock content: 40% by mass), 150 parts of tackifying resin (aliphatic / aromatic copolymer petroleum resin, softening point: 102°C), 65 parts of softener (paraffinic process oil), and 3 parts of antioxidant (hindered phenolic).

[0095] <Making adhesive sheets> A paper substrate (product name: OK Kinto single-sided, manufactured by Oji Paper Co., Ltd., thickness: 75 μm) was used as the base material. The prepared barrier layer-forming material (coating liquid) was applied to the surface of the paper substrate to form a coating film, and the coating film was dried at 70°C for 1 minute to form a barrier layer with a thickness of 1 μm. Next, a 20 μm thick hot-melt adhesive layer was formed by applying an adhesive composition melted at 140°C onto a release liner (a polyethylene terephthalate substrate coated with a silicone-based release agent, thickness: 50 μm) using a die coater. Furthermore, the barrier layer surface of the paper substrate and the hot-melt adhesive layer were laminated to produce an adhesive sheet. Regarding the adhesive sheet that was prepared, the brightness index (L) was measured immediately after preparation (within 8 hours of preparation) and 10 days later. * The degree of discoloration (lightness index ratio) was calculated by measuring the ) values. The evaluation results are shown in Table 1 below.

[0096] [Example 2 and Comparative Examples 2-4] In Example 1, a polyester resin was used as the resin for forming the barrier layer, and instead of using a mixture of toluene and methyl ethyl ketone (mass ratio 50:50, form: solvent solution) as the coating liquid used for forming the barrier layer, the resin and coating liquid listed in Table 1 below were used. Otherwise, an adhesive sheet was prepared in the same manner as in Example 1, and the lightness index (L) was measured immediately after preparation and after 10 days. * The degree of discoloration (lightness index ratio) was calculated by measuring the ) values. The results are shown in Table 1.

[0097] [Example 3] In Example 2, an adhesive sheet was prepared in the same manner as in Example 2, except that 6 parts by mass of the crosslinking agent listed in Table 1 below was added to 100 parts by mass of urethane-modified polyester resin. The lightness index (L) was measured immediately after preparation and 10 days later. * The degree of discoloration (lightness index ratio) was calculated by measuring the ) values. The results are shown in Table 1.

[0098] [Comparative Example 1] In Example 1, an adhesive sheet was prepared in the same manner as in Example 1, except that a hot-melt adhesive layer was formed directly on the substrate without forming a barrier layer. The lightness index (L) was measured immediately after preparation and 10 days later. * The degree of discoloration (lightness index ratio) was calculated by measuring the ) values. The results are shown in Table 1.

[0099] [Examples 4-6 and Comparative Examples 5-8] In Examples 1-3 and Comparative Examples 1-4, adhesive sheets were prepared in the same manner as in Examples 1-3 and Comparative Examples 1-4, except that synthetic paper (product name: Yupo, manufactured by Yupo Corporation, thickness: 80 μm) was used as the base material instead of paper. The degree of deformation (height difference (mm) relative to the standard) was measured for each of the obtained adhesive sheet samples. The results are shown in Table 2.

[0100] [Examples 7-9 and Comparative Examples 9-12] In Examples 1-3 and Comparative Examples 1-4, adhesive sheets were prepared in the same manner as in Examples 1-3 and Comparative Examples 1-4, except that a stretched polypropylene resin film (product name: Alphan SY101, manufactured by Oji F-Tex, thickness: 50 μm) was used as the base material instead of a paper base material. The degree of deformation (elongation (μm)) of each adhesive sheet sample obtained was measured after 7 days. The results are shown in Table 3.

[0101] [Examples 10-12 and Comparative Examples 13-16] In Examples 7-9 and Comparative Examples 9-12, adhesive sheets were prepared in the same manner as in Examples 7-9 and Comparative Examples 9-12, except that the barrier layer thickness was 0.5 μm instead of 1 μm. The degree of deformation (elongation (μm)) of each adhesive sheet sample obtained was measured after 7 days. The results are shown in Table 4.

[0102] [Examples 13-15 and Comparative Examples 17-20] In Examples 7-9 and Comparative Examples 9-12, adhesive sheets were prepared in the same manner as in Examples 7-9 and Comparative Examples 9-12, except that the barrier layer thickness was 0.1 μm instead of 1 μm. The degree of deformation (elongation (μm)) of each adhesive sheet sample obtained was measured after 7 days. The results are shown in Table 5.

[0103] [Example 16] In Example 1, instead of using a coating solution prepared by dissolving the resin in a mixture of toluene and methyl ethyl ketone (mass ratio 50:50, form: solvent solution) as the coating solution used to form the barrier layer, a 10% by mass aqueous resin dispersion solution, in which polyester resin 2 is dispersed in water, was used. Instead of using a paper substrate, coated paper (thickness: 89 μm, density 1.0 g / cm²) was used. 3 Using ), the coating liquid application amount is 1.0 g / m². 2 An adhesive sheet was prepared in the same manner as in Example 1, except that it was applied in the manner described above, and the L was measured immediately after preparation (within 8 hours of preparation) and after 7 days. * value, a * Value and b * The value is measured to determine the degree of discoloration (ΔE * The following was calculated. The coated paper was single-sided coated paper, and the barrier layer was formed on the side opposite the coated surface. The results are shown in Table 6.

[0104] [Examples 17-20] In Example 16, instead of using an aqueous resin dispersion in which "Polyester Resin 2" was dispersed in water as the coating liquid for forming the barrier layer, an aqueous resin dispersion with a solid content of 10% by mass, in which the resins listed in Table 6 below (when using Resin 2, the mass ratio of Resin 1 to Resin 2 is 1:1) were dispersed in water, was used. Otherwise, an adhesive sheet was prepared in the same manner as in Example 16, and the L values ​​were measured immediately after preparation and after 7 days. * value, a * Value and b * The value is measured to determine the degree of discoloration (ΔE * The result was calculated. The results are shown in Table 6.

[0105] [Comparative Example 21] An adhesive sheet was prepared in the same manner as in Example 16, except that a hot melt adhesive layer was formed directly on the substrate without forming a barrier layer. The L values ​​were measured immediately after preparation and after 7 days. * value, a * Value and b * The value is measured to determine the degree of discoloration (ΔE * The result was calculated. The results are shown in Table 6.

[0106] [Examples 21-23] In Example 16, instead of using an aqueous resin dispersion in which "Polyester Resin 2" is dispersed in water as the coating liquid for forming the barrier layer, an aqueous resin dispersion with a solid content of 10% by mass, in which the resins listed in Table 7 below (when using Resin 2, the mass ratio of Resin 1 to Resin 2 is 1:1) are dispersed in water, is used. Instead of using coated paper as the substrate, high-quality paper (thickness: 73 μm, density: 0.9 g / cm²) is used. 3 An adhesive sheet was prepared in the same manner as in Example 16, except that ) was used. For each adhesive sheet sample obtained, L was measured immediately after preparation (within 8 hours of preparation) and 7 days later. * value, a * Value and b * The value is measured to determine the degree of discoloration (ΔE * The result was calculated. The results are shown in Table 7.

[0107] [Comparative Example 22] In Examples 21-23, adhesive sheets were prepared in the same manner as in Examples 21-23, except that a hot-melt adhesive layer was formed directly on the substrate without forming a barrier layer. The L values ​​were measured immediately after preparation and after 7 days. * value, a * Value and b * The value is measured to determine the degree of discoloration (ΔE * The result was calculated. The results are shown in Table 7.

[0108] [Examples 24-30] In Example 16, instead of using an aqueous resin dispersion in which polyester resin 2 was dispersed in water, a 10% by mass aqueous resin dispersion in which the resins listed in Table 8 below (when resin 2 is used, the mass ratio of resin 1 to resin 2 is 1:1) was dispersed in water was used, and instead of using coated paper as the base material, synthetic paper (product name: Yupo, manufactured by Yupo Corporation, thickness: 80 μm) was used. Otherwise, an adhesive sheet was prepared in the same manner as in Example 16. The degree of deformation (height difference (mm) relative to the standard) was measured for each adhesive sheet sample obtained. The results are shown in Table 8.

[0109] [Comparative Example 23] In Examples 24-30, adhesive sheets were prepared in the same manner as in Examples 24-30, except that a hot-melt adhesive layer was formed directly on the substrate without forming a barrier layer. The degree of deformation (height difference (mm) relative to the reference) was measured for each adhesive sheet sample obtained. The results are shown in Table 8.

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3]

[0113] [Table 4]

[0114] [Table 5]

[0115] [Table 6]

[0116] [Table 7]

[0117] [Table 8]

[0118] Tables 1-8 show that by placing a barrier layer containing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins between the substrate and the hot-melt adhesive layer, it is possible to suppress the migration of the softener contained in the hot-melt adhesive layer to the substrate, thereby suppressing discoloration and deformation of the substrate. [Industrial applicability]

[0119] The adhesive sheet of the present invention can be used as an adhesive sheet for a wide range of applications, such as display labels, decorative labels, packaging films, window films, electromagnetic shielding labels, packaging, and sheets for electrical equipment. [Explanation of Symbols]

[0120] 1a, 1b Adhesive sheets 11 Base material 12 Barrier layer 13. Hot melt adhesive layer 14. Release Liner

Claims

1. An adhesive sheet having a base material and a hot melt adhesive layer containing a softening agent, The substrate and the hot-melt adhesive layer are disposed between them and further comprise a barrier layer containing at least one selected from the group consisting of polyester resins, polyurethane resins, and polyolefin resins. The aforementioned polyester resin is at least one of a polyester resin and a modified polyester resin. An adhesive sheet comprising the polyester resin and the polyurethane resin, each having a glass transition temperature of 40 to 130°C, and the polyolefin resin having a softening point of 0 to 100°C.

2. The adhesive sheet according to claim 1, wherein the glass transition temperature of the polyester resin is 40 to 100°C.

3. The adhesive sheet according to claim 1 or 2, wherein the substrate comprises at least one of paper and an olefin resin.

4. The density of the aforementioned paper is 0.9 g / cm³. ３ The adhesive sheet according to claim 3, which is superior.

5. The adhesive sheet according to any one of claims 1 to 4, wherein the thickness of the barrier layer is 0.01 to 10 μm.

6. The adhesive sheet according to any one of claims 1 to 5, wherein the polyester resin has a glass transition temperature of 40 to 90°C.

7. The adhesive sheet according to any one of claims 1 to 6, wherein the hot melt adhesive layer is a layer containing rubber and a tackifier.

8. The adhesive sheet according to any one of claims 1 to 7, further comprising a release liner on the hot melt adhesive layer opposite to the barrier layer.

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