Pressure-sensitive adhesive sheet laminate and method for producing the same

Abstract

The present invention pertains to an adhesive sheet laminate comprising: a substrate layer which is made of a thermoplastic resin composition (A) that contains a polypropylene-based resin as a main component; an adhesive layer which is made of a thermoplastic resin composition (B) that contains a specific thermoplastic resin (b) as a main component and that has a melt flow rate of 0.1-30 g / 10 min.; and a release layer which is made of a thermoplastic resin composition (C) that contains a specific thermoplastic resin (c) as a main component and that has a melt flow rate of 0.1-30 g / 10 min., wherein the adhesive sheet laminate has a tensile elastic modulus of not less than 2000 MPa.

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet laminate and a method for producing the same. [Background technology]

[0002] Pressure-sensitive adhesive sheets are used for a variety of purposes, such as packaging, fastening, bundling, surface protection, etc. In pressure-sensitive adhesive sheets, a release layer is usually attached to the surface of the pressure-sensitive adhesive layer that comes into contact with the adherend, i.e., the adhesive surface, to prevent foreign matter from adhering to the adhesive surface before the pressure-sensitive adhesive sheet is used, which would reduce the adhesive strength.

[0003] As such a pressure-sensitive adhesive sheet, Patent Document 1 discloses a method for producing a laminated film in which an adhesive layer is disposed between a release layer and a base layer, in which the resins of each layer are co-extruded into a cylindrical shape using a multilayer co-extrusion circular die and then cooled to obtain a laminated film. Patent Document 2 discloses a self-adhesive laminate consisting of a co-extruded laminated film of three resin layers that constitute at least a base layer, a self-adhesive layer, and a separate base layer.

[0004] Patent Document 3 discloses a biaxially oriented polypropylene film obtained by melt-kneading the resins used in the adhesive layer and core layer in an extruder and stretching a laminated sheet consisting of three or two resin layers using a resin confluence device. Patent Document 4 discloses a biaxially oriented self-adhesive protective film obtained by molding a sheet so as to be composed in this order of a self-adhesive layer / intermediate layer / non-adhesive layer, and then biaxially stretching the molded sheet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2005-111769 [Patent Document 2] Japanese Patent Publication No. 2007-320979 [Patent Document 3] Japanese Patent Application Publication No. 2014-200955 [Patent Document 4] Japanese Patent Publication No. 2015-93925 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the laminate films or laminates described in Patent Documents 1 and 2 are produced solely by extrusion molding, and therefore have low strength. Therefore, when peeling off the release layer or separate substrate layer and applying it to an adherend, or when peeling it from an adherend, the laminate film or laminate may stretch or tear. Furthermore, the resin used in the release layer or separate substrate layer does not have physical properties suitable for co-stretching with the substrate layer, and simply stretching these laminate films or laminates does not improve their strength. Furthermore, improvements have been desired in terms of achieving both good releasability of the release layer or separate substrate layer and good adhesion of the adhesive layer or self-adhesive layer to the adherend.

[0007] The films described in Patent Documents 3 and 4 are strong because they are stretched after coextrusion, but neither has a layer equivalent to a release layer; instead, the outermost layer is an adhesive or self-adhesive layer. Therefore, there are concerns that foreign matter may adhere to the surface of the adhesive or self-adhesive layer during film production, or that the adhesive or self-adhesive layer may stick to the surface, resulting in roll contamination, the generation of smearing, and poor die-cutting properties. Furthermore, because these films are generally handled in a rolled state, the outermost layer of the film opposite the adhesive layer is required to have releasability from the adhesive layer, i.e., anti-blocking properties. Because anti-blocking properties and printability are in a trade-off relationship, it is difficult to impart functions such as printability to such films. On the other hand, if a release layer is subsequently laminated onto the adhesive or self-adhesive layer of the film, the number of lamination steps increases, which raises concerns about increased costs.

[0008] In view of the above, the present invention aims to provide a high-strength adhesive sheet laminate in which a base layer, an adhesive layer, and a release layer can be laminated by co-extrusion, and which, by co-stretching these layers, has good adhesiveness and release properties, and a method for producing the same. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have discovered that by selecting resin compositions with specific physical properties as materials for the base layer, adhesive layer and release layer, particularly the adhesive layer and release layer, it is possible to obtain a high-strength adhesive sheet laminate that has good co-extrudability for the three layers and that also allows the laminated sheet obtained by co-extrusion to be stretched, thereby completing the present invention.

[0010] That is, the present invention relates to the following [1] to [8]. [1] A pressure-sensitive adhesive sheet laminate comprising a base layer, a pressure-sensitive adhesive layer, and a release layer laminated on the surface of the pressure-sensitive adhesive layer, The substrate layer is The thermoplastic resin composition (A) mainly contains a polypropylene-based resin, The adhesive layer has an indentation modulus of elasticity in the thickness direction of 100 MPa or less, and a thermoplastic resin composition (B) containing a thermoplastic resin (b) as a main component and having a melt flow rate of 0.1 to 30 g / 10 min; the thermoplastic resin (b) is compatible with the polypropylene-based resin, has a tensile modulus of elasticity of 100 MPa or less, and a melting point of 175°C or less; The release layer is a thermoplastic resin composition (C) containing a thermoplastic resin (c) as a main component and having a melt flow rate of 0.1 to 30 g / 10 min; the thermoplastic resin (c) is incompatible with the thermoplastic resin (b) and has a melting point of 175°C or less; A pressure-sensitive adhesive sheet laminate having a tensile modulus of elasticity of 2000 MPa or more. [2] The pressure-sensitive adhesive sheet laminate according to [1], wherein the thermoplastic resin (b) is an olefin-based elastomer or a styrene-based elastomer. [3] The thermoplastic resin (c) has a density of 0.94 g / cm 3 The pressure-sensitive adhesive sheet laminate according to [1] or [2] above, wherein the polyethylene is a polyethylene having a solubility parameter (SP value) of 8.3 or more, or the resin is a resin other than polyethylene. [4] The pressure-sensitive adhesive sheet laminate according to any one of [1] to [3] above, wherein the polypropylene resin has a tensile modulus of elasticity of 500 MPa or more. [5] The pressure-sensitive adhesive sheet laminate according to any one of the above [1] to [4], wherein the thermoplastic resin (c) is a polystyrene resin, an ethylene-vinyl alcohol copolymer, or a low-density polyethylene. [6] The pressure-sensitive adhesive sheet laminate according to any one of the above [1] to [5], wherein the base layer is a porous layer. [7] The pressure-sensitive adhesive sheet laminate according to any one of [1] to [6] above, further comprising a support layer on the surface of the base layer opposite to the pressure-sensitive adhesive layer. [8] A method for producing the pressure-sensitive adhesive sheet laminate according to any one of [1] to [7], a co-extrusion step of producing a laminated sheet by co-extruding the thermoplastic resin composition (A), the thermoplastic resin composition (B), and the thermoplastic resin composition (C); and A method for producing a pressure-sensitive adhesive sheet laminate, comprising a stretching step of stretching the obtained laminate sheet in at least one direction. [Effects of the Invention]

[0011] The pressure-sensitive adhesive sheet laminate according to the present invention can be produced in a small number of steps without incurring excessive costs because not only the base layer and pressure-sensitive adhesive layer but also the release layer can be laminated by co-extrusion. Furthermore, stretching after co-extrusion can increase the strength of the pressure-sensitive adhesive sheet laminate and adjust the peel strength of the release layer. Therefore, the pressure-sensitive adhesive sheet laminate can achieve not only high strength but also good adhesion and releasability. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified as desired without departing from the spirit of the present invention. Furthermore, the symbol "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0013] <Adhesive sheet laminate> The pressure-sensitive adhesive sheet laminate according to this embodiment comprises a base layer, a pressure-sensitive adhesive layer, and a release layer laminated on the surface of the pressure-sensitive adhesive layer, and has a tensile modulus of elasticity of 2000 MPa or more. The substrate layer is made of a thermoplastic resin composition (A) containing a polypropylene-based resin as a main component. The pressure-sensitive adhesive layer has an indentation modulus of elasticity in the thickness direction of 100 MPa or less and is made of a thermoplastic resin composition (B) containing a thermoplastic resin (b) as a main component. The thermoplastic resin composition (B) has a melt flow rate of 0.1 to 30 g / 10 min. The thermoplastic resin (b) is compatible with the polypropylene resin that is the main component of the thermoplastic resin composition (A), and has a tensile modulus of elasticity of 100 MPa or less and a melting point of 175°C or less. The release layer is made of a thermoplastic resin composition (C) containing a thermoplastic resin (c) as a main component. The thermoplastic resin composition (C) has a melt flow rate of 0.1 to 30 g / 10 min. The thermoplastic resin (c) is incompatible with the thermoplastic resin (b) constituting the adhesive layer, and has a melting point of 175°C or lower.

[0014] (base material layer) The substrate layer is made of a thermoplastic resin composition (A) containing a polypropylene-based resin as a main component. In this specification, the term "major component" in a thermoplastic resin composition means that the content of the polypropylene resin in the total amount of thermoplastic resin contained in the layer is 70% by mass or more. That is, the content of the polypropylene resin is 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more, based on the total amount of thermoplastic resin contained in the base layer. Furthermore, the thermoplastic resin contained in the thermoplastic resin composition (A) may be 100% by mass of polypropylene resin, i.e., a resin composition containing only polypropylene resin as the thermoplastic resin.

[0015] The polypropylene-based resin is not particularly limited, and examples thereof include homopolymers such as isotactic homopolypropylene and syndiotactic homopolypropylene obtained by homopolymerizing propylene, as well as polypropylene-based copolymers having various stereoregularities, which are obtained by copolymerizing propylene as a main component with α-olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. The polypropylene copolymer may be a binary or ternary or higher multi-component copolymer, and may be any of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

[0016] In order for the base layer to impart the necessary rigidity to the pressure-sensitive adhesive sheet laminate, the tensile modulus of the polypropylene resin is preferably 500 MPa or more, more preferably 800 MPa or more, even more preferably 1000 MPa or more, and even more preferably 1400 MPa or more. The tensile modulus of the polypropylene resin is the storage modulus at 23°C, measured in accordance with the method described in the Examples below.

[0017] The polypropylene resin may be synthesized or may be a commercially available product, and examples of commercially available products include Novatec PP FY-4 manufactured by Japan Polypropylene Corporation.

[0018] The polypropylene resin as the main component may be used alone or in combination of two or more kinds. When two or more kinds are used, the total content thereof should be 70% by mass or more.

[0019] The thermoplastic resin composition (A) may contain a thermoplastic resin other than the above polypropylene-based resin. The other thermoplastic resin is not particularly limited, but examples thereof include polyolefin resins other than polypropylene resins, such as polyethylene resins and polybutene; and functional group-containing olefin resins, such as ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, metal salts (ionomers) of ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid alkyl ester copolymers, maleic acid-modified polyethylene, and maleic acid-modified polypropylene. These may be used alone or in combination of two or more. The number of carbon atoms in the alkyl group in the ethylene-(meth)acrylic acid alkyl ester copolymer is preferably 1 to 8. In this specification, (meth)acrylic acid means at least one of acrylic acid and methacrylic acid.

[0020] Preferred polyethylene resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and copolymers of ethylene and α-olefins, and from the viewpoint of improving moldability, high-density polyethylene or low-density polyethylene is more preferred. Specific examples of copolymers of ethylene and α-olefins include polymers in which ethylene is the main component and propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. are copolymerized.

[0021] It is preferable that the substrate layer is a porous layer, since it can obtain the desired whiteness or opacity, improve the cushioning properties of the substrate layer, and minimize the impact on the appearance caused by air pockets that may occur during application to the adherend. Therefore, the thermoplastic resin composition (A) may further contain a filler in addition to the thermoplastic resin. The filler facilitates the formation of pores in the base layer, and also makes it easier to adjust the whiteness of the base layer.

[0022] The filler may be either an inorganic filler or an organic filler, and one type or two or more types may be used. Examples of inorganic fillers include calcium carbonate, calcined clay, silica, diatomaceous earth, talc, barium sulfate, aluminum sulfate, magnesium oxide, alumina, and ultraviolet absorbing fillers, such as titanium dioxide and zinc oxide.

[0023] Examples of organic fillers include polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-6,6, cyclic olefin polymers, copolymers of cyclic olefins and ethylene, etc. Resins having a melting point or glass transition point higher than the melting point of the polypropylene-based resin used are also examples of organic fillers.

[0024] The average particle size of the filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, from the viewpoint of facilitating the formation of the desired pores, and is preferably 10 μm or less, more preferably 8 μm or less, from the viewpoint of uniformity of the pores. The average particle size of the filler is determined by observing a cross section of the base layer in the thickness direction with an electron microscope and averaging the measured particle sizes of 100 particles randomly selected from the observation area. The particle size is determined from the maximum distance between two points on the particle's outline (maximum diameter).

[0025] The content of the filler in the thermoplastic resin composition (A) is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of easily obtaining a sufficient number of pores and easily imparting the desired whiteness or opacity to the pressure-sensitive adhesive sheet laminate, while from the viewpoint of suitably exerting the effects of the present invention, it is preferably 65% ​​by mass or less, more preferably 50% by mass or less.

[0026] The thermoplastic resin composition (A) may further contain various additives, such as commonly used ultraviolet absorbers, antistatic agents, antioxidants, antiaging agents, colorants (pigments), and slip agents, depending on the purpose, as long as the effects of the present invention are not impaired.

[0027] The base layer is co-extruded and co-stretched with the adhesive layer and the release layer. Therefore, it is preferable that the resins that are the main components of the thermoplastic resin compositions (A) to (C) that respectively constitute the base layer, adhesive layer, and release layer have similar melting points. The melting point of the polypropylene resin that is the main component of the thermoplastic resin composition (A) is approximately 160 to 180°C, and the melting point can be adjusted by the type and copolymerization ratio of the copolymerization components, molecular weight and molecular weight distribution, stereoregularity, etc.

[0028] The thickness of the substrate layer is usually 10 to 300 μm. The thickness of the substrate layer is preferably 30 μm or more, more preferably 50 μm or more, from the viewpoints of imparting rigidity to the pressure-sensitive adhesive sheet laminate, improving workability during application, and preventing material breakage during peeling due to insufficient breaking strength. Furthermore, from the viewpoints of application to curved surfaces and conformability to the surface shape of the adherend, the thickness is preferably 200 μm or less, more preferably 150 μm or less.

[0029] On the other hand, when the pressure-sensitive adhesive sheet laminate has a support layer described later, the thickness of the base layer and the support layer combined may be within the above range, and the base layer may be relatively thin. In this case, from the viewpoint of molding stability, the thickness of the base layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. There is no particular upper limit, and it is sufficient to adjust the total thickness including the support layer to 300 μm or less.

[0030] (Adhesive layer) The adhesive layer is made of a thermoplastic resin composition (B) containing a thermoplastic resin (b) as a main component. The melt flow rate (hereinafter sometimes referred to as "MFR") of the thermoplastic resin composition (B) is 0.1 to 30 g / 10 min, and the indentation modulus of the adhesive layer in the thickness direction is 100 MPa or less. In this specification, the melt flow rate refers to the melt flow rate measured in accordance with JIS K7210:1999 (230°C, 2.16 kg load). The indentation modulus refers to the indentation modulus of the adhesive layer surface measured using a nanoindenter.

[0031] By setting the indentation modulus of the adhesive layer in the thickness direction to 100 MPa or less, the adhesive layer can conform well to the surface shape of the adherend when attached to the adherend, and the anchoring effect results in excellent adhesiveness. The indentation modulus is preferably 50 MPa or less, and more preferably 10 MPa or less. Furthermore, from the viewpoint of adhesive residue on the adhesive layer, the indentation modulus is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and even more preferably 1 MPa or more. The indentation modulus is a value measured on the surface of the adhesive layer using a nanoindenter.

[0032] The indentation modulus can be adjusted by the type and blending of the thermoplastic resin contained in the thermoplastic resin composition (B), the thickness of the adhesive layer, etc. For example, the thicker the adhesive layer, the higher the indentation modulus, and the thinner the adhesive layer, the lower the modulus.

[0033] By setting the MFR of the thermoplastic resin composition (B) to 0.1 g / 10 min or more, the resin composition can be extruded at a low extrusion pressure. The MFR is preferably 1 g / 10 min or more. Furthermore, by setting the MFR to 30 g / 10 min or less, the discharge stability of the resin composition during extrusion molding can be improved. The MFR is preferably 20 g / 10 min or less, and more preferably 10 g / 10 min or less. The MFR can be adjusted by the composition of the thermoplastic resin (b) and other components.

[0034] The content of the thermoplastic resin (b) in the total amount of the thermoplastic resins contained in the thermoplastic resin composition (B) is 70 mass% or more, preferably 80 mass% or more, and more preferably 90 mass% or more. The thermoplastic resin contained in the thermoplastic resin composition (B) may be 100 mass% of the thermoplastic resin (b), i.e., the thermoplastic resin may consist solely of the thermoplastic resin (b).

[0035] The thermoplastic resin (b) is a resin compatible with the polypropylene resin, which is the main component of the thermoplastic resin composition (A) constituting the base layer. This improves the adhesion between the base layer and the adhesive layer. The thermoplastic resin (b) also has a tensile modulus of 100 MPa or less and a melting point of 175°C or less. Specifically, the thermoplastic resin (b) is preferably an olefin-based elastomer or a styrene-based elastomer. Whether or not a material is compatible with a polypropylene-based resin can be determined by its solubility parameter (SP value).

[0036] The thermoplastic resin (b) as the main component may be used alone or in combination of two or more. When two or more resins are used, the total content of these resins should be 70 mass % or more.

[0037] The olefin-based elastomer is not particularly limited as long as it has a tensile modulus of 100 MPa or less. For example, a copolymer of propylene and an α-olefin such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, or 1-decene is preferred. Such copolymers may be binary or ternary or higher multi-component systems. The higher the proportion of propylene-derived repeating units in a copolymer of propylene and an α-olefin, the higher the modulus tends to be.

[0038] When a copolymer of propylene and an α-olefin is used as the olefin-based elastomer, a resin different from the polypropylene-based resin that is the main component of the thermoplastic resin composition (A) is used. Specifically, the polypropylene-based resin in the thermoplastic resin composition (A) preferably has a tensile modulus of 500 MPa or more, more preferably 800 MPa or more, whereas the thermoplastic resin (b) that is the main component of the thermoplastic resin composition (B) has a tensile modulus of 100 MPa or less, which allows the two to be distinguished from one another. The tensile modulus of the thermoplastic resin (b) is the storage modulus at 23°C, measured according to the method described in the Examples below.

[0039] Specific examples of copolymers include propylene-ethylene copolymers, terpolymers such as propylene-ethylene-1-butene copolymers, propylene-ethylene-1-pentene copolymers, propylene-ethylene-1-hexene copolymers, propylene-ethylene-4-methyl-1-pentene copolymers, propylene-ethylene-1-heptene copolymers, propylene-ethylene-1-octene copolymers, propylene-ethylene-1-nonene copolymers, and propylene-ethylene-1-decene copolymers. Among these, propylene-ethylene copolymer or propylene-ethylene-1-butene copolymer is particularly preferred from the viewpoint of adhesive strength and high compatibility with the polypropylene resin contained in the base layer.

[0040] The olefin-based elastomer may be a synthesized product or a commercially available product. Examples of commercially available products include Tafmer PN-3560 manufactured by Mitsui Chemicals, Inc. and Xelas MC717R4 manufactured by Mitsui Chemicals, Inc.

[0041] The styrene elastomer is not particularly limited as long as it has a tensile modulus of elasticity of 100 MPa or less, but examples thereof include hydrogenated styrene-butadiene copolymer (HSBR), styrene-ethylene-butylene-ethylene copolymer (SEBC), styrene-ethylene-butylene-styrene copolymer (SEBS), etc. Among these, hydrogenated styrene-butadiene copolymer (HSBR) is preferred because of its good thermal stability.

[0042] From the viewpoint of flexibility and adhesive strength of the adhesive layer, the styrene content of the styrene-based elastomer is preferably 30% by mass or less, more preferably 20% by mass or less, and from the viewpoint of adhesive strength, the styrene content is preferably 5% by mass or more, more preferably 8% by mass or more.

[0043] The styrene elastomer may be a synthesized product or a commercially available product, and an example of a commercially available product is Dynaron 1320P manufactured by JSR Corporation.

[0044] From the viewpoint of controlling the MFR of the thermoplastic resin composition (B), the MFR of the thermoplastic resin (b) is preferably 0.1 g / 10 min or more, more preferably 1 g / 10 min or more, and is preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, and even more preferably 10 g / 10 min or less.

[0045] The thermoplastic resin composition (B) may contain other components as long as the effects of the present invention are not impaired.

[0046] The other components include, for example, a tackifier. By blending a tackifier, the elastic modulus of the adhesive layer is reduced. Examples of tackifiers include synthetic petroleum resins, terpene resins, terpene phenol resins, aromatic modified terpene resins, coumarone-indene resins, natural resin rosin, modified rosin, glycerin ester rosin, pentaerythritol ester rosin, phenol resins, xylene resins, alicyclic petroleum resins, dicyclopentadiene resins, etc. These may be used alone or in combination of two or more.

[0047] In addition to the above, the thermoplastic resin composition (B) may contain, as necessary, various additives that are commonly used, such as an ultraviolet absorber, an antistatic agent, an antioxidant, an antiaging agent, a colorant (pigment), and a slip agent, within the range that does not impair the effects of the present invention.

[0048] The adhesive layer is co-extruded and co-stretched with the base layer and the release layer. The melting point of the polypropylene resin, which is the main component of the thermoplastic resin composition (A), is about 160 to 180°C. Considering that the adhesive layer is co-stretched with the base layer containing the polypropylene resin at about 140 to 160°C, the melting point of the thermoplastic resin (b) is 175°C or lower, preferably 170°C or lower, and more preferably 165°C or lower. Furthermore, if the melting point is too low, there is a concern that the adhesive layer may not be oriented by stretching, so the melting point is preferably 140°C or higher, and more preferably 150°C or higher. When the thermoplastic resin (b) does not have a melting point, the glass transition point is preferably 110°C or lower.

[0049] The thickness of the adhesive layer is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more from the viewpoint of adhesive strength, and is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less from the viewpoint of releasability from the release layer.

[0050] (peeling layer) The release layer is made of a thermoplastic resin composition (C) containing a thermoplastic resin (c) as a main component, and has an MFR of 0.1 to 30 g / 10 min.

[0051] By setting the MFR of the thermoplastic resin composition (C) to 0.1 g / 10 min or more, the resin composition can be extruded at a low extrusion pressure. The MFR is preferably 1 g / 10 min or more. Furthermore, by setting the MFR to 30 g / 10 min or less, the discharge stability of the resin composition during extrusion molding can be improved. The MFR is preferably 20 g / 10 min or less, and more preferably 10 g / 10 min or less. The MFR can be adjusted by the composition of the thermoplastic resin (c) and other components.

[0052] The content of the thermoplastic resin (c) in the total amount of thermoplastic resins contained in the thermoplastic resin composition (C) is 70 mass% or more, preferably 80 mass% or more, and more preferably 90 mass% or more. The thermoplastic resin contained in the thermoplastic resin composition (C) may be 100 mass% of the thermoplastic resin (c), i.e., the thermoplastic resin (c) alone.

[0053] The thermoplastic resin (c) is a resin incompatible with the thermoplastic resin (b), which is the main component of the thermoplastic resin composition (B). Therefore, the release layer made of the thermoplastic resin composition (C) containing the thermoplastic resin (c) as the main component has good releasability from the adhesive layer. Whether or not the thermoplastic resin (c) is incompatible with the thermoplastic resin (b) can be determined by the density or solubility parameter of the thermoplastic resin (c). Specifically, when the thermoplastic resin (c) is polyethylene, the density is 0.94 g / cm 3When the thermoplastic resin (c) is other than polyethylene, it is preferable to select a resin having a solubility parameter (SP value) of 8.3 or more, more preferably 9 or more, and even more preferably 10 or more. By using the thermoplastic resin composition (C) containing such a thermoplastic resin (c) as a main component, a release layer having good releasability from the adhesive layer can be formed. The SP value in this specification is calculated based on the Fedors method described below. SP value (δ) = [ΣE / ΣV] 1 / 2 E: Cohesive energy constant (cal / mol), calculated as the sum of the cohesive energy constants of the atoms or atomic groups that make up the compound. V: Molecular volume (cm 3 / mol) and is calculated as the sum of the molar volumes of the atoms or atomic groups that make up the compound. The cohesive energy constant can be determined from the numerical values ​​described in "Polymer Handbook, 4th Edition, John Wiley & Sons." In this specification, the unit of the SP value is (cal / cm 3 ) 1 / 2 is.

[0054] Since thermoplastic resin (b) is compatible with the polypropylene-based resin that is the main component of thermoplastic resin (A), the incompatibility of thermoplastic resin (c) with thermoplastic resin (b) means that it is also incompatible with the polypropylene-based resin in thermoplastic resin (A). Considering that the SP value of polypropylene is generally 8.0, the present inventors have found that by selecting a resin with an SP value of 8.3 or more as the thermoplastic resin (c), a release layer with better releasability can be obtained. However, when polyethylene is selected as the thermoplastic resin (c), polyethylenes with different densities have different compatibility with polypropylene, even though they have the same SP value. That is, when the density is 0.94 g / cm 3It has been found that low-density polyethylene of less than 100% is preferable as the thermoplastic resin (c) because it has low compatibility with polypropylene. Here, the density of polyethylene is a value measured in accordance with Method D (density gradient tube method) of JIS K 7112:1999 "Method for measuring density and specific gravity of plastics - non-foamed plastics."

[0055] The release layer is co-extruded and co-stretched together with the base layer and the adhesive layer. The polypropylene resin, which is the main component of the thermoplastic resin composition (A), has a melting point of about 160 to 180°C, and is co-stretched with the base layer containing the polypropylene resin at about 140 to 160°C. Therefore, from the viewpoint of smoothly performing the co-extrusion and co-stretching, the melting point of the thermoplastic resin (c) is 175°C or lower, preferably 170°C or lower, and more preferably 165°C or lower. Furthermore, if the melting point is too low, there is a concern that the resin may not be stretch-oriented, so the melting point is preferably 140°C or higher, and more preferably 150°C or higher. When the thermoplastic resin (c) does not have a melting point, the glass transition point is preferably 110°C or lower.

[0056] The thermoplastic resin (c) that is the main component may be used alone or in combination of two or more. When two or more resins are used, the total content thereof should be 70 mass % or more.

[0057] The thermoplastic resin (c) is not particularly limited as long as it has a melting point of 175°C or less and is incompatible with the thermoplastic resin (b). For example, low-density polyethylene resin (LDPE), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate (EEA) copolymer, polystyrene resin, polymethyl methacrylate resin (PMMA), polyacetal resin (POM), ethylene-vinyl alcohol (EVOH) copolymer, etc. can be used. Among these, low-density polyethylene resin, polystyrene resin, or ethylene-vinyl alcohol copolymer is preferred from the viewpoint of the interlayer peel strength (peelability) between the adhesive layer and the release layer after co-stretching. The low-density polyethylene resin is a resin having a density of 0.94 g / cm. 3 This means a polyethylene resin of less than

[0058] The resin may be synthesized or commercially available. Examples of commercially available resins include Novatec LD LC540 manufactured by Japan Polyethylene Corporation, HIPS408 manufactured by PS Japan Co., Ltd., and EVAL G156B manufactured by Kuraray Co., Ltd.

[0059] From the viewpoint of controlling the MFR of the thermoplastic resin composition (C), the MFR of the thermoplastic resin (c) is preferably 0.1 g / 10 min or more, more preferably 1 g / 10 min or more, and is preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, and even more preferably 10 g / 10 min or less.

[0060] The thermoplastic resin composition (C) may contain other components to the extent that the adhesive strength is not affected. Other components include, for example, a release agent, which can be used to suitably control the release force of the release layer. The release agent is not particularly limited, but examples thereof include amine-based release agents, silicon-based release agents, fluorine-based release agents, hydrocarbon-based release agents, metal soap-based release agents, etc. These release agents may be used alone or in combination of two or more. Among these, amine-based release agents, silicone-based release agents, fluorine-based release agents, and metal soap-based release agents are preferred, with amine-based release agents being more preferred, and among the amine-based release agents, saturated fatty acid bisamides are more preferred.

[0061] In addition to the above, the thermoplastic resin composition (C) may contain, as necessary, various additives that are commonly used, such as an ultraviolet absorber, an antistatic agent, an antioxidant, an antiaging agent, a colorant (pigment), and a slip agent, within the range that does not impair the effects of the present invention.

[0062] Thermoplastic resin composition (C) containing thermoplastic resin (c) as the main component can be used to obtain a pressure-sensitive adhesive sheet laminate having the desired peel strength by adjusting the thermoplastic resin (c), other components, stretching conditions, etc. depending on the application.

[0063] The thickness of the release layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, from the viewpoint of preventing breakage during peeling. Also, from the viewpoint of providing a strong stiffness and preventing peeling during molding, the thickness of the release layer is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. In order to improve the workability of the peeling operation, a peeling aid layer may be provided on the surface of the release layer opposite to the surface facing the adhesive layer. Examples of the peeling aid layer include the same as those for the support layer described below, and preferred examples are also the same.

[0064] (Support layer) The pressure-sensitive adhesive sheet laminate comprises the above-mentioned base layer, pressure-sensitive adhesive layer and pressure-sensitive adhesive layer in this order, and may further comprise a support layer on the surface of the base layer opposite to the pressure-sensitive adhesive layer. When only the release layer is peeled off from the surface of the adhesive layer in the adhesive sheet laminate to be used as an adhesive sheet, the provision of a support layer makes it easier to adjust the rigidity and processability of the adhesive sheet.

[0065] The support layer is not particularly limited as long as it can provide the desired rigidity and processability to the pressure-sensitive adhesive sheet. For example, a thermoplastic resin film containing a thermoplastic resin such as a polyolefin resin, a polyester resin, or polyvinyl chloride can be used. As the thermoplastic resin, one of these may be used or two or more may be used in combination. The support layer may be a single layer or a laminated structure of two or more layers.

[0066] From the viewpoint of adhesion to the base layer, it is preferable that the SP value is close to that of the base layer, and therefore polyolefin resins are preferred.

[0067] The support layer is preferably a porous layer, similar to the base layer, because it can achieve the desired whiteness or opacity, improve the cushioning properties of the support layer, and minimize the impact on the appearance caused by air pockets that occur during attachment to the adherend. To form a porous layer, for example, similar to the base layer, a method can be used in which a filler is incorporated into the resin composition that constitutes the support layer and the resin composition is stretched.

[0068] Examples of the filler include the same fillers as those that can be contained in the thermoplastic resin composition (A). The preferred average particle size and content of the filler in the resin composition are also the same as those of the filler in the thermoplastic resin composition (A).

[0069] (Other layers) When the pressure-sensitive adhesive sheet laminate includes a support layer, it may further include at least one of a print layer and a print-receiving layer on the surface of the support layer opposite to the side on which the base layer is located.

[0070] The printed layer is a layer consisting of characters, images, etc. formed with printing ink or toner, and various printing methods can be used, such as offset printing, inkjet printing, electrophotography (laser), thermal recording, and thermal transfer printing. Therefore, the printed layer is located on the outermost surface of the pressure-sensitive adhesive sheet laminate, opposite the release layer. The printed layer needs to cover at least a portion of the surface of the pressure-sensitive adhesive sheet laminate, and may cover the entire surface. The printing layer can be a conventionally known one and can be formed by a known method.

[0071] The print-receiving layer is a layer that functions as an ink or toner-receiving layer when a print layer is provided. Depending on the properties of the print-receiving layer, it is possible to adjust the various properties of the print layer, such as abrasion resistance, antistatic property, printability, water resistance, and storage stability. The print-receiving layer can be a conventionally known one, and can be formed by a known method.

[0072] In addition to the printing layer and the print-receiving layer, the pressure-sensitive adhesive sheet laminate may be provided with any other layer as long as the effects of the present invention are not impaired. Examples of such other layers include a protective layer provided on the surface of the printing layer, and a printing layer, print-receiving layer, or antistatic layer provided on the surface of the release layer, i.e., the surface opposite the pressure-sensitive adhesive layer.

[0073] (Physical Properties) The pressure-sensitive adhesive sheet laminate can be produced by laminating the base layer, adhesive layer, and release layer by co-extrusion using the thermoplastic resin compositions (A) to (C), respectively, and then subjecting the layers to a co-stretching step. By undergoing the co-stretching step, the tensile modulus of the pressure-sensitive adhesive sheet laminate can be increased to 2000 MPa or more. The tensile modulus is preferably 3000 MPa or more, and more preferably 4000 MPa or more. There is no particular upper limit to the tensile modulus of the pressure-sensitive adhesive sheet laminate, but it is typically 6000 MPa or less. By achieving a tensile modulus equal to or greater than the lower limit, the pressure-sensitive adhesive sheet laminate can be provided with the required rigidity, resulting in effects such as improved ease of application when applied to an adherend, improved punching processability, and prevention of stretching and tearing of the sheet when peeled from an adherend. The tensile modulus in this specification refers to the storage modulus at 23°C, measured in accordance with the method described in the Examples below. The tensile modulus is measured in the TD direction (vertical direction), but if the TD direction is unknown, the measured value in the direction in which the tensile modulus of the pressure-sensitive adhesive sheet laminate is highest is used.

[0074] The co-stretching step not only adjusts the tensile modulus but also the balance between the adhesive strength and peel strength between the adhesive layer and the release layer within an appropriate range, thereby achieving good releasability and excellent adhesion when the adhesive layer is applied to an adherend.

[0075] The releasability of the release layer is evaluated by the peel force (peel strength) obtained in a T-type tensile test at a take-up speed of 300 mm / min under a test environment of a temperature of 20 to 23°C and a humidity of 50 to 60% RH, and is preferably 1 N / 15 mm or less, more preferably 0.5 N / 15 mm or less, from the viewpoint of preventing damage to the adhesive layer and the base layer. Although there is no particular lower limit, a peel force of 0.1 N / 15 mm or more is preferred from the viewpoint of preventing unintentional peeling of the release layer.

[0076] The adhesive strength of the adhesive layer after peeling off the release layer is measured in accordance with JIS Z 0237:2000. The adhesive strength obtained by such measurement is preferably 0.3 N / 15 mm or more, more preferably 0.5 N / 15 mm or more. Although there is no particular upper limit, from the viewpoint of the peel strength from the release layer, the adhesive strength is preferably 10 N / 15 mm or less.

[0077] (Method of manufacturing pressure-sensitive adhesive sheet laminate) The pressure-sensitive adhesive sheet laminate according to this embodiment can be obtained by co-extruding a base layer, a pressure-sensitive adhesive layer, and a release layer, followed by co-stretching. Specifically, the method for producing a pressure-sensitive adhesive sheet laminate includes a co-extrusion step of producing a laminate sheet by co-extruding the thermoplastic resin composition (A), the thermoplastic resin composition (B), and the thermoplastic resin composition (C), and a stretching step of stretching the obtained laminate sheet in at least one direction.

[0078] In the co-extrusion process, laminating each layer by co-extrusion reduces the number of steps, leading to cost savings. Furthermore, when forming an adhesive layer by coating the thermoplastic resin composition (B) on a substrate layer, it is necessary to remove a large amount of the organic solvent used as a solvent or dispersion medium during drying after coating. However, by adopting a co-extrusion process, there is no need to use an organic solvent, which has the advantage of reducing the environmental load.

[0079] In the stretching process, the laminated sheet obtained in the co-extrusion process is stretched in at least one direction, thereby controlling the peel strength of the release layer from the adhesive layer within an appropriate range. If the peel strength is too low, the release layer will peel off during molding, printing, transportation, etc. On the other hand, if the peel strength is too high, problems such as difficulty in peeling the release layer during use or part of the adhesive layer remaining on the surface of the release layer will occur.

[0080] Although it is difficult to control the peel strength by simply co-extruding a multilayer film containing an adhesive layer and a release layer, the peel strength can be easily controlled by further co-stretching. For example, by increasing the stretch ratio, the peel strength between the adhesive layer and the release layer can be reduced.

[0081] Such co-extrusion and co-stretching can be achieved by selecting a substrate layer, adhesive layer, and release layer made of specific thermoplastic resin compositions (A) to (C) in the adhesive sheet laminate.

[0082] For example, when an adhesive layer is formed using a thermoplastic resin composition (B) containing an olefin-based elastomer or a styrene-based elastomer as the thermoplastic resin (b), and a release layer is formed using a thermoplastic resin composition (C) containing a polystyrene-based resin, an ethylene-vinyl alcohol copolymer, or a low-density polyethylene as the thermoplastic resin (c), the stretching ratio of the laminate sheet including the base layer, adhesive layer, and release layer after co-extrusion is preferably about 5 to 10. When biaxially stretching is performed, it is preferable to stretch about 2 to 5 times in the machine direction, i.e., the longitudinal direction (MD) of the laminate sheet, and about 5 to 10 times in the transverse direction, i.e., the width direction (TD) of the laminate sheet.

[0083] The pressure-sensitive adhesive sheet laminate is usually cut or punched appropriately depending on the application. The appropriate peel strength also varies depending on the area after cutting or punching. For example, a relatively high peel strength is required when the area is small, and a relatively low peel strength is sufficient when the area is large. In this way, the peel strength can be controlled within an appropriate range by selecting an appropriate stretching ratio and the materials of each layer described above depending on the application.

[0084] When a support layer is provided on the surface of the base layer, the method for forming the support layer can be appropriately selected. For example, the support layer may be bonded to the surface of the base layer that has been subjected to the co-extrusion step and the stretching step, but preferably any one of the following methods (a) to (c) can be used. (a) A laminate sheet is produced by co-extruding a support layer together with a base layer, an adhesive layer, and a release layer, and this is co-stretched in a stretching step to obtain an adhesive sheet laminate on which a support layer is formed. (b) A laminated sheet is produced by co-extruding a base layer, an adhesive layer, and a release layer, and a support layer is extrusion laminated onto the surface of the base layer of the laminated sheet. The entire laminate is then co-stretched to obtain an adhesive sheet laminate with a support layer formed thereon. (c) The base layer, adhesive layer, and release layer are co-extrusion laminated onto the surface of the support layer, and then the entire assembly is co-stretched to obtain a pressure-sensitive adhesive sheet laminate on which the support layer is formed. [Example]

[0085] The present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0086] [Evaluation method] (Melting Point) The melting point of the thermoplastic resin constituting the thermoplastic resin composition was measured using a differential scanning calorimeter (AS-3DX manufactured by Hitachi High-Tech Science Corporation) with a sample weight of 10 mg at a heating rate of 10°C / min, and the melting peak temperature was determined as the melting point. The results are shown in Table 2. In the table, "-" means that the melting point is not shown.

[0087] (glass transition temperature) The glass transition temperature of the thermoplastic resin constituting the thermoplastic resin composition was determined using the following method. First, a 500 μm-thick sheet of the thermoplastic resin was prepared using a hydraulic press, which was then cut into a 30 mm x 15 mm test piece. Using this test piece, dynamic viscoelasticity measurements were performed using a solid viscoelasticity measuring device (TA Instruments Japan: RSA-III) under the following conditions: chuck distance 20 mm, measurement frequency 10 Hz, strain 0.1%, heating rate 10°C / min, and tension mode. The loss tangent (tanδ) was determined. The temperature at which the obtained tanδ peaked was taken as the glass transition temperature. The results are shown in Table 2.

[0088] (Thickness) The total thickness of the entire pressure-sensitive adhesive sheet laminate was measured in accordance with JIS K7130:1999 using a constant pressure thickness measuring instrument (manufactured by Teclock Corporation, trade name: PG-01J). To measure the thickness of each layer in the pressure-sensitive adhesive sheet laminate, the pressure-sensitive adhesive sheet laminate was cooled to a temperature of -60°C or below with liquid nitrogen. The sample was placed on a glass plate and cut at a right angle with a razor blade (manufactured by Schick Japan Co., Ltd., product name: Proline Blade) to prepare a sample for cross-sectional observation. The cross-section of the obtained sample was observed using a scanning electron microscope (manufactured by JEOL Ltd., product name: JSM-6490). The boundary lines between the thermoplastic resin compositions were identified from the compositional appearance, and the thickness ratio of each layer was calculated. The thickness of each layer in the pressure-sensitive adhesive sheet laminate was then calculated by multiplying the total thickness of the entire pressure-sensitive adhesive sheet laminate measured above by the thickness ratio of each observed layer. The results are shown in Table 2.

[0089] (Melt flow rate: MFR) The MFR of the thermoplastic resin was measured in accordance with JIS K7210:1999 using a small melt indexer (trade name OK-0309, manufactured by Tateyama Scientific Industrial Co., Ltd.). The measurement conditions were a measurement temperature of 230°C and a load of 2.16 kg. The results are shown in Table 2.

[0090] (Tensile modulus of thermoplastic resin (b)) A 500 μm thick sheet of thermoplastic resin (b) was prepared using a hydraulic press, and then cut into a 30 mm x 15 mm test piece. Dynamic viscoelasticity measurements were performed on this test piece using a solid viscoelasticity measuring device (TA Instruments Japan: RSA-III). The measurement conditions were a chuck distance of 20 mm, a measurement frequency of 10 Hz, a strain of 0.1%, a heating rate of 10°C / min, and tension mode. The storage modulus in the transverse (TD) direction (vertical) at 23°C was taken as the tensile modulus. The results are shown in Table 2.

[0091] (Tensile modulus of adhesive sheet laminate) The pressure-sensitive adhesive sheet laminate was cut into test pieces measuring 30 mm long x 15 mm wide, and dynamic viscoelasticity measurements were performed using a solid viscoelasticity measuring device (TA Instruments Japan: RSA-III). The measurement conditions were a chuck distance of 20 mm, a measurement frequency of 10 Hz, a strain of 0.1%, a heating rate of 10°C / min, and tension mode, and the TD (vertical) storage modulus at 23°C was taken as the tensile modulus. The results are shown in Table 2. A tensile modulus of 2000 MPa or higher is considered satisfactory, and a tensile modulus of 3000 MPa or higher is considered even better.

[0092] (peel force) A 50 μm polyethylene terephthalate (PET) film was attached to the release layer side of the adhesive sheet laminate using a laminating adhesive, and the sample was left to stand for one day in a test environment of 20-23°C temperature and 50-60% RH to prepare a sample for peel strength evaluation. A small peel was applied between the release layer and adhesive layer at the edge of a 200mm x 15mm sample for evaluation of peel strength. The peeled portion was chucked between the upper and lower chucks of a tensile tester (Orientec Co., Ltd., model RTG-1225), and a T-type tensile test was performed at a take-up speed of 300mm / min under a test environment of 20-23°C and 50-60% RH. The peel strength (peel strength) was measured. The peel strength was evaluated according to the following criteria: A and B were acceptable, and C was unacceptable. The results are shown in Table 2. A (very good): Peeling force is 0.5N / 15mm or less B (Good): Peeling force is over 0.5N / 15mm and less than 1N / 15mm C (poor): The peeling force was more than 1 N / 15 mm or the base material layer was broken.

[0093] (Adhesive strength) The adhesive strength of the adhesive layer of the adhesive sheet laminate was measured in accordance with JIS Z 0237:2000. Specifically, the adhesive sheet laminate was cut into a test piece measuring 200 mm long x 25 mm wide, and the release layer was peeled off to expose the adhesive layer. The adhesive layer portion was attached to a SUS430BA adherend whose surface had been cleaned with toluene, and a 2 kg roller was moved back and forth once on the surface of the support layer to press the adherend. 30 minutes after pressing, the test piece was peeled in a 180-degree direction at a pulling rate of 300 mm / min to measure the adhesive strength. The adhesive strength was evaluated according to the following criteria: A and B were acceptable, and C was unacceptable. The results are shown in Table 2. In the table, "-" means that the peel force was too great, causing the material to break when the adhesive layer was exposed, making it impossible to measure the adhesive strength. A (very good): Adhesive strength of 0.5N / 15mm or more B (Good): Adhesive strength is 0.3N / 15mm or more and less than 0.5N / 15mm C (poor): Adhesive strength less than 0.3N / 15mm

[0094] (Indentation elastic modulus of adhesive layer) The release layer was peeled from the adhesive sheet laminate, and a drop of instant adhesive (Aron Alpha (registered trademark), professional impact resistant, manufactured by Toagosei Co., Ltd.) was applied to the surface of the support layer. The adhesive sheet was then fixed to a sample holder dedicated to the measurement device using the instant adhesive. The indentation modulus of the adhesive layer was then measured. The measurement device used was the Elionix Nanoindenter "ENT-2100." The measurement conditions were a triangular pyramidal diamond indenter (Berkovich indenter) with a 115° inter-edge angle, a load-unload test mode, a maximum load of 3 μN, a hold time at maximum load of 1 s, and a loading and unloading rate of 10 μN / sec. The measurement data were processed using the dedicated analysis software (version 6.18) provided with the measurement device to determine the indentation modulus (MPa) of the adhesive layer in the thickness direction. The results are shown in Table 2. An indentation modulus of 100 MPa or less is considered acceptable, with 50 MPa or less being preferable. In the table, "-" means that the peeling force was too great and the material broke when the release layer was peeled off, making it impossible to measure the indentation modulus. A (very good): Indentation modulus is 50 MPa or less B (Good): Indentation modulus is over 50 MPa and 100 MPa or less C (poor): Indentation modulus exceeds 100 MPa

[0095] [Example 1] To prepare resin composition D1 listed in Table 1, a mixture of PP:CaCO3 = 80:20 (mass ratio) was melt-kneaded in an extruder set at 230°C. The mixture was then fed into an extrusion die set at 250°C and extruded into a sheet, which was then cooled to 60°C using a cooling device to obtain an unstretched sheet. This unstretched sheet was heated to 135°C and stretched 5 times in the machine direction using the difference in peripheral speed between a group of rolls to form a support layer. Next, the resin compositions A1, B1, and C1 constituting each thermoplastic resin composition were melt-kneaded in three extruders set at 250°C, and then extruded into a sheet on the surface of the support layer so that the thermoplastic resin composition A1 layer, which would become the base layer, faced the support layer, to obtain a four-layer laminate sheet, which was then cooled to 60°C. Next, the four-layer laminate sheet was heated to approximately 150°C using a tenter oven and stretched 8.5 times in the transverse direction, and then further heated to 160°C for heat treatment. It was then cooled to 60°C, and the edge portions were slit to obtain a pressure-sensitive adhesive sheet laminate with a thickness of 100µm, resin compositions for each layer (release layer / adhesive layer / substrate layer / support layer), components for each layer (LDPE / PO-based / PP / PP+CaCO3), thicknesses for each layer (10µm / 5µm / 15µm / 70µm), and number of stretching axes for each layer (uniaxial / uniaxial / uniaxial / biaxial).

[0096] [Examples 2 and 3 and Comparative Examples 1 and 2] Pressure-sensitive adhesive sheet laminates were obtained in the same manner as in Example 1, except that the thermoplastic resin composition forming the release layer was changed from resin composition C1 to resin compositions C2, C3, C4, and C5, respectively.

[0097] [Example 4] A pressure-sensitive adhesive sheet laminate was obtained in the same manner as in Example 3, except that the thermoplastic resin composition forming the pressure-sensitive adhesive layer was changed from resin composition B1 to resin composition B2.

[0098] [Table 1]

[0099] [Table 2]

[0100] From the above results, it was found that by appropriately selecting the resin compositions that make up each layer of an adhesive sheet laminate, it is possible to co-extrude and co-stretch, and to obtain a high-strength adhesive sheet laminate with an excellent balance of adhesiveness and peelability.

[0101] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2020-058708) filed on March 27, 2020, the contents of which are incorporated herein by reference.

Claims

1. A pressure-sensitive adhesive sheet laminate comprising a base layer, a pressure-sensitive adhesive layer, and a release layer laminated on the surface of the pressure-sensitive adhesive layer, The substrate layer is The thermoplastic resin composition (A) comprises a polypropylene-based resin as a main component, The adhesive layer is a layer having an indentation modulus of elasticity in the thickness direction of 100 MPa or less, and a thermoplastic resin composition (B) containing a thermoplastic resin (b) as a main component and having a melt flow rate of 0.1 to 30 g / 10 min; the thermoplastic resin (b) is an olefin-based elastomer or a styrene-based elastomer having a tensile modulus of 100 MPa or less and a melting point of 175°C or less; The release layer is a thermoplastic resin composition (C) containing a thermoplastic resin (c) as a main component and having a melt flow rate of 0.1 to 30 g / 10 min; the thermoplastic resin (c) is a polystyrene-based resin, an ethylene-vinyl alcohol copolymer, or a low-density polyethylene, each having a melting point of 175°C or less; A pressure-sensitive adhesive sheet laminate having a tensile modulus of elasticity of 2000 MPa or more.

2. The thermoplastic resin (c) has a density of 0.94 g / cm ３ 2. The pressure-sensitive adhesive sheet laminate according to claim 1, wherein the resin is polyethylene having a solubility parameter (SP value) of 8.3 or more, or a resin other than polyethylene having a solubility parameter (SP value) of 8.3 or more.

3. The pressure-sensitive adhesive sheet laminate according to claim 1 or 2, wherein the polypropylene resin has a tensile modulus of elasticity of 500 MPa or more.

4. The pressure-sensitive adhesive sheet laminate according to any one of claims 1 to 3, wherein the substrate layer is a porous layer.

5. The pressure-sensitive adhesive sheet laminate according to any one of claims 1 to 4, further comprising a support layer on the surface of the base layer opposite to the pressure-sensitive adhesive layer.

6. A method for producing the pressure-sensitive adhesive sheet laminate according to any one of claims 1 to 5, a co-extrusion step of producing a laminated sheet by co-extruding the thermoplastic resin composition (A), the thermoplastic resin composition (B), and the thermoplastic resin composition (C); and A method for producing a pressure-sensitive adhesive sheet laminate, comprising a stretching step of stretching the obtained laminate sheet in at least one direction.

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