TWI851570B - Laminated Film - Google Patents

Abstract

The present invention relates to a laminated film, which has little change in adhesive force due to components transferred from an adherend and is not prone to floating due to cutting of the adherend after lamination.

Description

Laminated film

The present invention relates to a laminated film which has little change in adhesive force due to components transferred from an adherend and is not prone to floating due to cutting after lamination.

In the past, laminated films (also commonly referred to as surface protection films, protective tapes, adhesive films, etc.) having a substrate and an adhesive layer laminated on one side thereof have been widely used to protect the surfaces of components such as optical devices, metal plates, coated metal plates, resin plates, and glass plates (e.g., Patent Documents 1 to 3). When laminated films are used to protect the aforementioned components, such as the surface of polyvinyl chloride containing plasticizers, which may cause the plasticizer to migrate to the laminated film and cause the adhesive force to change. In the past, it was known to add a plasticizer that would migrate to the laminated film in advance to suppress the change in adhesive force (Patent Document 1) to solve the aforementioned problem. However, there is a disadvantage that the plasticizer added to the laminate film may contaminate the surface of the adherend.

[Prior Art Literature] [Patent Literature]

Patent document 1: Japanese Patent Application Publication No. 6-923

Patent document 2: Japanese Patent Application Publication No. 2010-6925

Patent document 3: Japanese Patent Application Publication No. 2016-186044

The subject of the present invention is to provide a laminated film which, when bonded to a substrate whose surface is segregated over time due to additives, has less change in adhesion due to components transferred from the substrate and is less likely to float due to cutting of the substrate after bonding.

The above-mentioned problem can be achieved by a laminate film, which is a laminate film having a resin layer A on one side of a substrate, and the glass transition temperature (Tg) of the resin layer A, the storage modulus of the resin layer A at -15°C measured at a frequency of 1 Hz and a strain of 0.01% (hereinafter represented as G'(-15°C)), and the storage modulus of the resin layer A at 0°C measured at a frequency of 1 Hz and a strain of 0.01% (hereinafter represented as G'(0°C)) satisfy all of the following relationships (a), (b), and (c):

(a) Tg ≧ -14℃

(b)G’(-15℃)/G’(0℃)≦5.0

(c) 10MPa<G’(-15℃)<100MPa

According to the present invention, it is possible to provide a laminated film which has little change in adhesive force due to components transferred from an adherend and is less likely to float due to cutting after lamination.

[Form used to implement the invention]

The present invention is described in detail below. However, the present invention is not limited to the embodiments described below.

The laminated film of the present invention comprises a substrate and a resin layer A on one side thereof. The resin layer A preferably has adhesiveness at room temperature and is a layer with a limited thickness.

The lower limit of the glass transition temperature (Tg) of the resin layer A is -14°C. The lower limit of the glass transition temperature (Tg) of the resin layer A is preferably -10°C. When the glass transition temperature (Tg) of the resin layer A is lower than -14°C, after being attached to an adherend, it may be difficult to peel off due to the transferred components from the adherend. The upper limit is not particularly set, but it is preferably 40°C, more preferably 10°C, further preferably 0°C, and particularly preferably -3°C. When the glass transition temperature (Tg) of the resin layer A is greater than 40°C, the adhesion may be reduced.

The glass transition temperature (Tg) of the resin layer A is a value obtained by measuring by the method described below. When the resin layer A is composed of a plurality of resins or contains particles, it refers to the glass transition temperature measured in the state of a mixture of all components constituting the resin layer A.

The upper limit of G’(-15℃)/G’(0℃) of the aforementioned resin layer A is 5.0. The upper limit of G’(-15℃)/G’(0℃) is preferably 4.8, and more preferably 4.6. After the laminated film of the present invention is bonded to the adherend, even if components contained in the adherend are transferred to the laminated film, the adhesion change is small and a stable adhesion over time can be obtained. The inventors of the present invention have discovered that this can be achieved by reducing the ratio of G’(-15℃) to G’(0℃) of the resin layer A. Therefore, if G’(-15℃)/G’(0℃) becomes greater than 5.0, there is a possibility that the adhesion change after bonding becomes larger due to the transferred components from the adherend. The lower limit of G'(-15℃)/G'(0℃) is not particularly set, but is preferably 1.2, more preferably 3.0, and particularly preferably 4.0. If G'(-15℃)/G'(0℃) is lower than 1.2, the adhesive force may be too strong and peeling may become difficult.

The laminated film of the present invention comprises a substrate and a resin layer A on one side thereof. The G’(-15°C) of the resin layer A satisfies the relationship of 10MPa<G’(-15°C)<100MPa. G’(-15°C) is preferably greater than 20MPa, more preferably greater than 24MPa. G’(-15°C) is preferably less than 80MPa, more preferably less than 45MPa, and particularly preferably less than 40MPa. If the G’(-15°C) of the resin layer A becomes less than 10MPa, the adhesive force during lamination will become too high, and peeling may become difficult. If the G'(-15℃) of the resin layer A becomes 100MPa or more, floating due to cutting after bonding becomes easy to occur. In addition, the G'(-15℃) and G'(0℃) of the resin layer A are storage moduli obtained by measuring by the method described below.

The composition of the resin layer A constituting the laminated film of the present invention is not particularly limited as long as it does not impair the effects of the present invention, and known adhesives such as acrylic, silicone, natural rubber, and synthetic rubber can be used. Among these, from the perspective of recyclability, thermoplastic synthetic rubber adhesives are preferably used, and styrene elastomers are more preferably used.

As for the aforementioned styrene-based elastomer, styrene/butadiene copolymers such as styrene/isoprene/styrene copolymers (SIS) and styrene/butadiene/styrene copolymers (SBS) can be exemplified. And hydrogenated products thereof can be exemplified. For example, hydrogenated styrene/butadiene copolymers (HSBR), styrene/ethylene butylene/styrene triblock copolymers (SEBS), styrene/ethylene butylene diblock copolymers (SEB). Or styrene/isobutylene copolymers, such as styrene/isobutylene/styrene triblock copolymers (SIBS) and styrene/isobutylene diblock copolymers (SIB). Or a mixture thereof can be used.

Among the above, styrene/butadiene/styrene copolymer (SBS) and other styrene/copolymers of styrene/copolymers and their hydrogenated products, or styrene/isobutylene copolymers are preferably used. Only one type of styrene elastomer may be used, or two or more types may be used in combination. Furthermore, materials other than styrene elastomers may be used as needed.

Regarding the content of the aforementioned styrene-based elastomer, from the viewpoint of the conditions related to the storage modulus that should be satisfied in order to achieve the purpose of the invention, when the resin layer A as a whole is set to 100 mass %, the lower limit is preferably 50 mass %, more preferably 60 mass %, and further preferably 65 mass %, and the upper limit is preferably 90 mass %, more preferably 80 mass %, and further preferably 75 mass %.

The lower limit of the weight average molecular weight of the aforementioned styrene elastomer is preferably 50,000. If the weight average molecular weight is lower than 50,000, the cohesive force of the resin layer A may be reduced, and residue may be generated when it is peeled off from the adherend. The upper limit of the weight average molecular weight of the styrene elastomer is preferably 400,000, and more preferably 300,000. If the weight average molecular weight exceeds 400,000, the viscosity may be increased, and the productivity may be reduced.

The lower limit of the styrene content in the aforementioned styrene-based elastomer is preferably 5 mass%, more preferably 10 mass%, and further preferably 15 mass%, when the entire styrene-based elastomer is set to 100 mass%. If the styrene content is less than 5 mass%, the cohesive force of the resin layer A will be reduced, and there will be a situation where residual glue occurs when it is peeled off from the adherend. On the other hand, the upper limit of the styrene content in the styrene-based elastomer is preferably 60 mass%, more preferably 40 mass%, and further preferably 30 mass%. If it exceeds 60 mass%, the adhesion to the adherend will be reduced, and in particular, the adhesion will be insufficient to the adherend with uneven surfaces.

From the viewpoint of adjusting the glass transition temperature (Tg) and adjusting the storage modulus, the resin layer A of the present invention preferably contains an adhesion-imparting agent. Examples of the adhesion-imparting agent include aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins, alicyclic petroleum resins, terpene resins, terpene phenol resins, rosin resins, alkylphenol resins, and xylene resins. Alternatively, a hydrogenated product obtained by hydrogenating the unsaturated bonds of these resins (hereinafter referred to as hydrogenated) may be used. In terms of the hydrogenation rate of unsaturated bonds in the resin before hydrogenation, the resin in which 90% or more of the unsaturated bonds are hydrogenated is defined as a completely hydrogenated resin, and the resin in which 10% or more and less than 90% of the unsaturated bonds are hydrogenated is defined as a partially hydrogenated resin. The hydrogenation rate is calculated by measuring the ¹ H NMR (400 MHz) of the resin and comparing the peak area value of 0.3 ppm or more and 3.3 ppm or less corresponding to the structure after the unsaturated bonds are hydrogenated with the peak area value of 5.0 ppm or more and 7.4 ppm or less corresponding to the structure before the unsaturated bonds are hydrogenated. Hereinafter, for example, a resin obtained by hydrogenating 10% or more and less than 90% of the unsaturated bonds of an aromatic petroleum resin is described as an aromatic partially hydrogenated petroleum resin, and a resin obtained by hydrogenating 90% or more of the unsaturated bonds of an aromatic petroleum resin is described as an aromatic fully hydrogenated petroleum resin.

The upper limit of the content of the aforementioned adhesive agent is preferably 50% by mass, more preferably 38% by mass, and further preferably 33% by mass, when the resin layer A as a whole is set to 100% by mass. If the content of the adhesive agent is more than 50% by mass, after the laminated film of the present invention is attached to the adherend, there may be a situation where adhesive residues are generated during peeling and contaminate the adherend, or a part of the adhesive agent may seep out to the surface of the resin layer A over time or during heated storage, and the adhesive force may become excessive. The lower limit of the content of the aforementioned adhesive agent is preferably 10% by mass, more preferably 20% by mass, and further preferably 25% by mass.

The above-mentioned adhesion-imparting agent is preferably used in combination of two or more types. When two or more types are used in combination, from the viewpoint of adjusting the glass transition temperature (Tg) and adjusting the storage modulus, it is preferred to use at least one resin selected from each of the following two groups: a group including aliphatic petroleum resins, aromatic fully hydrogenated petroleum resins and alicyclic petroleum resins (hereinafter referred to as Group A), and a group including aromatic petroleum resins, aromatic partially hydrogenated petroleum resins and terpene resins (hereinafter referred to as Group B).

That is, in the present invention, the resin layer A preferably includes all of the following (d) to (f).

(d) Styrene elastomer

(e) at least one resin selected from the group consisting of aliphatic petroleum resins, aromatic fully hydrogenated petroleum resins and alicyclic petroleum resins

(f) at least one resin selected from the group consisting of aromatic petroleum resins, aromatic partially hydrogenated petroleum resins and terpene resins.

From the viewpoint of adjusting the glass transition temperature (Tg) and the storage modulus, it is more preferable to use at least one resin selected from each of the following two groups: a group including aromatic fully hydrogenated petroleum resins and alicyclic petroleum resins (hereinafter referred to as A' group), and a group including aromatic petroleum resins and aromatic partially hydrogenated petroleum resins (hereinafter referred to as B' group). In addition, the softening point of the resin in both the A' group and the B' group is preferably above 110°C, and more preferably above 120°C. The softening point of the resin can be obtained by the global method specified in JIS K-2207:2006.

That is, in the present invention, a more preferred aspect is that the resin layer A includes all of the following (d) to (f).

(d) Styrene elastomer

(e) at least one resin selected from the group consisting of aromatic fully hydrogenated petroleum resins having a softening point of 110°C or higher and alicyclic petroleum resins having a softening point of 110°C or higher

(f) at least one resin selected from the group consisting of aromatic petroleum resins having a softening point of 110°C or higher and aromatic partially hydrogenated petroleum resins having a softening point of 110°C or higher.

As for the A' group resins having a softening point of 110°C or higher, examples include the "Arkon" P series (P115, P125, P140) manufactured by Arakawa Chemicals, and the "T-REZ" H series (HA125, HB125) manufactured by TonenGeneral. As for the B' group resins having a softening point of 110°C or higher, examples include the "Arkon" M series (M115, M135) manufactured by Arakawa Chemicals.

The lower limit of the content of the resin selected from Group A is preferably 5% by mass, more preferably 8% by mass, and further preferably 10% by mass. If the content of the resin selected from Group A is less than 5% by mass, the adhesive force will be reduced and floating will be likely to occur. On the other hand, the upper limit of the resin selected from Group A is preferably 25% by mass, more preferably 20% by mass, and further preferably 17% by mass. If the content of the resin selected from Group A exceeds 25% by mass, the adhesive force will be too high and peeling will be difficult. The lower limit of the content of the resin selected from Group B is preferably 5% by mass, more preferably 8% by mass, and further preferably 10% by mass. If the content of the resin selected from group B is less than 5% by mass, the adhesive force will be reduced and floating will be likely to occur. On the other hand, the upper limit of the resin selected from group B is preferably 25% by mass, more preferably 20% by mass, and further preferably 17% by mass. If the content of the resin selected from group B exceeds 25% by mass, the adhesive force will be too high and peeling will be difficult.

That is, in the present invention, when the entire resin layer A is set to 100 mass %, the resin layer A preferably includes the following (1) and (2).

(1) At least one resin selected from the group consisting of aliphatic petroleum resins, aromatic fully hydrogenated petroleum resins and alicyclic petroleum resins: 5-25% by mass

(2) At least one resin selected from the group consisting of aromatic petroleum resins, aromatic partially hydrogenated petroleum resins and terpene resins: 5-25% by mass.

The resin layer A of the present invention preferably contains a component that is soluble in chloroform and acetone and has a glass transition temperature (Tg_sol) of 50°C or higher. Here, the glass transition temperature (Tg_sol) refers to the glass transition temperature of a component that is soluble in both chloroform and acetone, obtained by extracting the chloroform-soluble component of the resin layer A with chloroform and then extracting the obtained chloroform-soluble component with acetone.

Furthermore, when the resin layer A as a whole is set to 100 mass %, the lower limit of the content of the components in the resin layer A that are soluble in chloroform and acetone and have a glass transition temperature (Tg_sol) of 50°C or more is preferably 10 mass %, and more preferably 25 mass %. If the content of the components that are soluble in chloroform and acetone and have a glass transition temperature (Tg_sol) of 50°C or more becomes less than 10 mass %, the adhesive force will be reduced and floating will occur. On the other hand, when the resin layer A as a whole is set to 100 mass %, the upper limit of the content of the component soluble in chloroform and acetone and having a glass transition temperature (Tg_sol) of 50°C or higher in the resin layer A is preferably 50 mass %, more preferably 40 mass %, and further preferably 33 mass %. If the content of the component soluble in chloroform and acetone and having a glass transition temperature (Tg_sol) of 50°C or higher exceeds 50 mass %, the adhesion will become too high and peeling will become difficult.

As for the component which is soluble in chloroform and acetone and has a glass transition temperature (Tg_sol) of 50°C or above, for example, a resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins, or alicyclic petroleum resins, terpene resins, terpene phenol resins, rosin resins, alkylphenol resins, xylene resins, and hydrogenated products of these resins (aromatic fully hydrogenated petroleum resins, aromatic partially hydrogenated petroleum resins, etc.) with a softening point of 110°C or above can be used. In particular, from the viewpoint of adjusting the glass transition temperature (Tg) and storage modulus of the resin layer A, it is more preferable to use a resin having a glass transition temperature (Tg_sol) of 65°C or higher and a softening point of 130°C or higher.

In the resin layer A of the present invention, in addition to the aforementioned styrene elastomer, an olefinic resin may be added. By adding an olefinic resin, the adhesion may be adjusted or good film forming properties may be obtained. As olefin resins, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, low-crystalline, amorphous ethylene/α-olefin copolymers, ethylene/propylene/diene terpolymers (ethylene-propyleue-diene terpolymers), crystalline polypropylene, low-crystalline polypropylene, amorphous polypropylene, propylene/ethylene copolymers (random copolymers and/or block copolymers), propylene/α-olefin copolymers, propylene/ethylene/α-olefin copolymers, polybutene, 4-methyl-1-pentene/α-olefin copolymers, ethylene/ethyl (meth)acrylate copolymers, ethylene/methyl (meth)acrylate copolymers, ethylene/n-butyl (meth)acrylate copolymers, and ethylene/vinyl acetate copolymers can be cited. These can be used alone or in combination. The α-olefin is not particularly limited as long as it can be copolymerized with ethylene, propylene, or 4-methyl-1-pentene, and examples thereof include ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

Among the aforementioned olefin resins, low-density polyethylene, linear low-density polyethylene, ethylene/α-olefin copolymer, polypropylene, propylene/α-olefin copolymer, polybutene, low-crystalline polypropylene, amorphous polypropylene, and 4-methyl-1-pentene/α-olefin copolymer are more preferably used. The upper limit of the olefin resin content is preferably 80% by mass, more preferably 50% by mass, and further preferably 40% by mass, when the entire resin layer A is set to 100% by mass.

The resin layer A of the present invention may also contain particles for the purpose of adjusting the adhesive force of the resin layer A. As for the particles, for example, inorganic particles and organic particles can be used, and organic particles that are less likely to be damaged by the adherend are preferred. As for the organic particles, acrylic resin particles, styrene resin particles, polyolefin resin particles, polyester resin particles, polyurethane resin particles, polycarbonate resin particles, polyamide resin particles, silicone resin particles, and fluorine resin particles can be exemplified. Alternatively, copolymer resin particles of two or more monomers used in the synthesis of the above-mentioned resins can be cited, and these can be used alone or in combination.

A lubricant may also be added to the resin layer A of the present invention. By adding a lubricant, the chips are prevented from sticking to each other and agglomerating when the styrene elastomer is formed into chips; or the lubricant is precipitated on the surface of the resin layer A to adjust the adhesion, so that good extrudability can be obtained when the resin layer A is melt-extruded. Examples of lubricants include fatty acid metal salts such as calcium stearate or magnesium behenate, fatty acid amides such as ethylenebistearate and hexamethylenebistearate, and waxes such as polyethylene wax, polypropylene wax, and wax. The upper limit of the lubricant content is preferably 10 mass%, more preferably 5 mass%, and further preferably 3 mass%, when the resin layer A as a whole is set to 100 mass%. When the lubricant content is more than 10 mass%, there may be a situation where the adhesion is insufficient, especially to an object with uneven surfaces, or when the resin layer A is formed by melt extrusion, a part of the lubricant may sublime and contaminate the nozzle, and further adhere to the product.

In addition, the resin layer A may also contain additives such as nucleating agents, antioxidants, heat resistance agents, weathering agents, antistatic agents, etc. for the purpose of imparting functions to the resin layer A. These additives can be used alone or in combination, and the upper limit of the total content is preferably 3% by mass, and more preferably 2% by mass, when the resin layer A as a whole is set to 100% by mass. When the total content of the additives exceeds 3% by mass, there is a possibility that the additives will seep out of the resin layer A and cause defects in the product or contaminate the adherend.

The lower limit of the thickness of the resin layer A is not particularly limited, but is preferably 3 μm, more preferably 5 μm, and further preferably 7 μm. If the thickness of the resin layer A is less than 3 μm, the adhesive force of the resin layer A may be reduced. In addition, the upper limit of the thickness of the resin layer A is preferably 30 μm, more preferably 20 μm, and further preferably 15 μm. If the thickness of the resin layer A exceeds 30 μm, it may become difficult to peel off the laminated film from the surface of the adherend.

The substrate constituting the laminated film of the present invention is not particularly limited, but as the resin used for the substrate, for example, polyolefin or polyester can be used, and from the viewpoint of productivity and processability, polyolefin is preferably used as the main component. The main component described here refers to the one with the highest mass % (the one with the highest content) among the components constituting the substrate layer of the laminated film.

As for the aforementioned polyolefin, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene/α-olefin copolymers, polypropylene, propylene/ethylene copolymers (random copolymers and/or block copolymers), propylene/α-olefin copolymers, propylene/ethylene/α-olefin copolymers, ethylene/propylene/diene terpolymers, ethylene/ethyl (meth)acrylate copolymers, ethylene/methyl (meth)acrylate copolymers, ethylene/n-butyl (meth)acrylate copolymers, and ethylene/vinyl acetate copolymers can be cited. These can be used alone or in combination. Furthermore, as for the aforementioned α-olefin, if it can be copolymerized with propylene or ethylene, it is not particularly limited, and for example, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene can be cited. Among the above-mentioned polyolefins, polyethylene is particularly preferred from the viewpoint of processability.

The aforementioned substrate may also contain additives such as antistatic agents, release agents, antioxidants, weathering agents, nucleating agents, etc., and resin modifiers such as polyolefins, polyesters, polyamides, and elastomers, within the scope that does not impair the effects of the present invention.

The lower limit of the thickness of the substrate is not particularly limited, but is preferably 25 μm, more preferably 45 μm. If the thickness of the substrate is less than 25 μm, the laminated film may be easily broken during operation. The upper limit of the thickness of the substrate is preferably 200 μm, more preferably 188 μm. If the thickness of the substrate exceeds 200 μm, a curling mark may remain on the substrate.

Furthermore, from the viewpoint of improving the affinity between the resin layer A and the substrate and the adhesion between the resin layer A and the substrate interface, it is preferred that the substrate of the laminated film of the present invention contains a small amount of each component constituting the resin layer A, including a styrene-based elastomer used for the resin layer A. Furthermore, as a method of making the substrate contain adhesive layer components, a method of adding recycled raw materials obtained by recycling and re-making the laminated film is adopted, which is a preferred method from the viewpoint of recycling the resin or reducing the production cost.

The substrate may also have a resin layer B on the side not having the resin layer A. The lower limit of the arithmetic mean surface roughness Ra of the roughness of the resin layer B is preferably 0.20 μm, more preferably 0.30 μm, further preferably 0.35 μm, and particularly preferably 0.45 μm. The laminated film of the present invention can adjust the roughness of the resin layer A by transferring the shape of the resin layer B to the resin layer A when the laminated film is rolled up. By making the arithmetic average surface roughness of the resin layer B within the above range, the resin layer A can be roughened during winding, reducing the contact area between the laminated film and the adherend, and suppressing the transfer of plasticizer from the adherend. When the arithmetic average surface roughness of the resin layer B is less than 0.20μm, the resin layer A will not be sufficiently roughened by winding, the amount of plasticizer transfer increases, and peeling may become difficult. Regarding the roughness of the resin layer B, the upper limit of the arithmetic average roughness Ra is not particularly set, but is preferably 2.0μm. If the arithmetic mean roughness Ra is too large, the roughness of the resin layer A may become too large due to transfer, and the adhesive force may decrease.

As the resin used in the resin layer B, for example, polyolefin and polyester can be used, and polyolefin as the main component is preferred from the viewpoint of productivity and processability. The main component described here refers to the one with the highest mass % (the one with the highest content) among the components constituting the base layer of the laminated film.

As for the aforementioned polyolefin, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene/α-olefin copolymers, polypropylene, propylene/ethylene copolymers (random copolymers and/or block copolymers), propylene/α-olefin copolymers, propylene/ethylene/α-olefin copolymers, ethylene/ethyl (meth)acrylate copolymers, ethylene/methyl (meth)acrylate copolymers, ethylene/n-butyl (meth)acrylate copolymers, and ethylene/vinyl acetate copolymers can be cited. These can be used alone or in combination. Furthermore, as for the aforementioned α-olefin, if it can be copolymerized with propylene or ethylene, it is not particularly limited, and for example, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene can be cited. The aforementioned substrate may also contain additives such as antistatic agents, release agents, antioxidants, weathering agents, nucleating agents, etc., and resin modifiers such as polyolefins, polyesters, polyamides, and elastomers within the range that does not impair the effects of the present invention. Among the aforementioned polyolefins, propylene/ethylene block copolymers are particularly preferred from the perspective of adjusting the roughness.

The resin layer B may also contain a release agent. Examples of the release agent include fluorine resins, silicone resins, fatty acid metal salts, fatty acid amides, inorganic particles, and organic particles. Without the release agent, the surface shape of the resin layer A may be deformed during the winding and unfolding of the laminated film, and the adhesive force may be reduced. Among the release agents, from the perspective of the release effect, it is preferred to use at least one selected from the group consisting of silicone resins and organic particles, and more preferably to use two of them in combination.

The lower limit of the thickness of the resin layer B is not particularly limited, but is preferably 1 μm, more preferably 2 μm. If the thickness of the substrate is less than 1 μm, productivity may be reduced. In addition, the upper limit of the thickness of the resin layer B is preferably 20 μm, more preferably 10 μm, from the perspective of cost.

The method for manufacturing the laminated film of the present invention is not particularly limited, and examples thereof include: co-extrusion molding; T-die molding; a method of laminating other layers on a layer previously obtained by co-extrusion molding, T-die molding or inflation molding by known lamination methods such as extrusion lamination and extrusion coating; a method of laminating the obtained films by dry lamination after each layer is independently formed into a film, etc. However, from the perspective of productivity, the co-extrusion molding method in which the materials of the aforementioned substrate and the aforementioned resin layer A are supplied to a multi-layer extruder for molding is preferred, and from the perspective of thickness accuracy, the T-die molding method is more preferred.

In the case of manufacturing by co-extrusion molding, each base material and the constituent components of the resin layer A are extruded from a melt extruder. At this time, the upper limit of the extrusion temperature of the resin is preferably 250°C, more preferably 230°C, and further preferably 220°C. When the extrusion temperature of the resin exceeds 250°C, thermal degradation of the resin occurs, and it may become easy to generate residual glue during adhesive peeling. The lower limit is not particularly set, but when the resin temperature is lower than 180°C, the melt viscosity is too high and the productivity decreases.

The laminated film of the present invention has little change in adhesive force when it is stored in contact with the adherend, and is not prone to floating due to cutting after bonding. Therefore, it can be suitably used as a surface protection film for various items. In particular, it can be suitably used as a surface protection film for building components. More specifically, the laminated film of the present invention is preferably used for protecting the surface of decorative steel plates.

[Implementation example]

The present invention is described in more detail with reference to the following embodiments, but the present invention is not limited to the embodiments.

(1) Storage modulus G’

Only the resin layer A was scraped from the laminated film using a stainless steel scraper, and the melt-molded film was used as a sample with a thickness of 1 mm. The measurement was performed using a rheometer AR2000ex manufactured by TA Instruments. The temperature was raised from -50°C to +50°C at a rate of 10°C/min, while dynamic shear deformation was performed at a frequency of 1 Hz and a strain of 0.01%, and the storage modulus G'(-15°C) and G'(0°C) at -15°C and 0°C were measured.

(2) Glass transition temperature (Tg)

Only the resin layer A was scraped off from the laminated film using a stainless steel scraper, and after heating it to 180°C to melt it, it was formed into a thickness of 1mm and cooled to -50°C at 15°C/min as a sample. The measurement was performed using a rheometer AR2000ex manufactured by TA Instruments. While heating the temperature range from -50°C to +50°C at a heating rate of 10°C/min, dynamic shear deformation was performed at a frequency of 1Hz and a strain of 0.01%, and tanδ was measured at a temperature above -50°C and below 50°C. Among the obtained tanδ, the temperature at which tanδ reaches a maximum value between -50°C and 50°C is set as Tg. In the case of two or more maximum values, the maximum value on the high temperature side is set as Tg.

(3) Surface roughness

The arithmetic mean roughness Ra of the resin layer B was evaluated by using a high-precision fine shape measuring instrument (SURFCORDER ET4000A) manufactured by Kosaka Laboratory Co., Ltd. in accordance with JIS B0601-1994. The range of the laminated film and the adherend was 2 mm in the width direction and 0.2 mm in the length direction. The scanning direction was set to the width direction, and 21 measurements were performed at intervals of 10 μm in the length direction. The three-dimensional analysis was also performed and evaluated. In addition, a diamond needle with a stylus tip radius of 2.0 μm was used, and the measurement force was 100 μN and the cutoff was 0.8 mm.

(4) Glass transition temperature (Tg_sol) and content of components soluble in chloroform and acetone

A product obtained by scraping only the resin layer A from a laminated film using a stainless steel scraper was prepared. A chloroform-soluble component was extracted from the scraped product using chloroform. The obtained chloroform-soluble component was extracted with acetone to extract components soluble in both chloroform and acetone. When the mass of the product obtained by scraping the resin layer A was set to 100 mass %, the ratio of the mass of the above extract was set to the content of the components soluble in chloroform and acetone. Then, 5 mg of the above extract was measured and heated and cooled in a nitrogen atmosphere according to the following procedure using a differential scanning calorimeter (EXSTAR DSC6220 manufactured by Seiko Instruments).

program

Step 1: Heat from 25°C to 200°C at 10°C/min, and then maintain at 200°C for 5 minutes.

Step 2: Cool from 200°C to 25°C at -10°C/min and keep at 25°C for 5 minutes.

Step 3: After heating from 25°C to 150°C at 10°C/min, maintain at 150°C for 5 minutes.

In the temperature increase process of step 3, when looking at the DSC graph from 150°C toward the low temperature side, the maximum temperature at which the slope of the DSC graph changes from the slope of the baseline is set to T_1, and the minimum temperature at which the slope of the DSC graph returns to the slope of the baseline at a temperature lower than T_1 is set to T_2, and Tg_sol is obtained by the following calculation formula.

Calculation formula: Tg_sol=(T_1+T_2)/2

(5) Softening point

The softening point of the resin was measured based on the global method specified in JIS K-2207:2006.

(6) Thickness

Using the microtome method, an ultrathin section with a cross-section width of 5 mm in the width direction of the laminate film and the thickness direction of the laminate body was prepared, and the cross-section was platinum-coated to prepare an observation sample. Next, a field emission scanning electron microscope (S-4800) manufactured by Hitachi, Ltd. was used to observe the cross-section of the laminate film at an accelerating voltage of 1.0 kV, and the thickness of the substrate, resin layer A, resin layer B, and the total thickness of the laminate film were measured from any part of the observation image. Regarding the observation magnification, the resin layers A and B were set to 10,000 times, and the substrate and laminate film were set to 1,000 times. Furthermore, the same measurement was performed 20 times in total, and the average value was used as the thickness of each of the substrate, resin layers A and B, and the total thickness of the laminated film.

(7) Lamination of laminated films

The resin layer A side of the laminated film of the Example and the Comparative Example stored/conditioned at a temperature of 23°C and a relative humidity of 50% for 24 hours was attached to the polyvinyl chloride surface of the polyvinyl chloride coated steel plate as a member containing an additive using a roller press (special press roller manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at a bonding pressure of 2 kg/ ^cm2 . The polyvinyl chloride coated steel plate was prepared so that the arithmetic average surface roughness Ra of the polyvinyl chloride coated surface was 2.2 μm.

(8) Adhesion

The following two types of samples were prepared: one in which the bonded sample obtained in (7) was stored in a room at 23°C for 24 hours, and one in which the bonded sample obtained in (7) was stored in a room at 40°C under a pressure of 6 kg/ ^cm2 for 96 hours. The adhesion strength of the two types of samples was measured using a tensile tester (ORIENTEC Co., Ltd. "TENSILON" universal testing machine) at a tensile speed of 20 m/min, a peeling angle of 180°, and a measuring temperature of 23°C. Hereinafter, the adhesion of the sample laminated according to the procedure (7) above and stored in a room at 23°C for 24 hours is recorded as adhesion (23°C), and the adhesion of the sample laminated according to the procedure (7) above and stored in a room at 40°C under a pressure of 6 kg/ ^cm2 for 96 hours is recorded as adhesion (40°C). The lower the adhesion (23°C), the easier it is to float during cutting after lamination, and the higher the adhesion (23°C), the harder it is to peel off. From the perspective of floating during cutting and peeling properties, the following three stages were evaluated.

◎: Adhesion (23°C) is 100 g/25 mm or more and 250 g/mm or less.

○: The adhesive force (23° C.) is 80 g/25 mm or more and less than 100 g/25 mm, or the adhesive force (23° C.) is more than 250 g/mm and less than 350 g/25 mm.

×: Adhesion (23° C.) is less than 80 g/25 mm or greater than 350 g/25 mm.

(9) Adhesion ratio

Adhesion ratio = Adhesion (40℃) / Adhesion (23℃)‧‧‧(a)

Since the closer the adhesion ratio calculated based on the above formula (a) is to 1, the smaller the effect of the transferred components from the adherend on the adhesion of the laminated film is, the evaluation was performed in the following three stages.

◎: The adhesion ratio is 0.8 or more and less than 3.5.

○: The adhesion ratio is 3.5 or more and less than 4.0.

×: The adhesion ratio is less than 0.8 or is 4.0 or more.

<Resin>

‧(E1) (Trade name "H1052", styrene content 20% by mass, styrene/ethylene butylene/styrene triblock copolymer, manufactured by Asahi Kasei Corporation, MFR 13g/10min (measured at 230℃, 2.16kg))

‧(E2) (Trade name "8903P", styrene content 35% by mass, styrene/ethylene butylene/styrene triblock copolymer, manufactured by JSR, MFR 10g/10min (measured at 230℃, 2.16kg))

‧(E3) (Trade name "G1657", styrene content 13% by mass, styrene/ethylene butylene/styrene triblock copolymer, manufactured by Kraton, MFR 10g/10min (measured at 230℃, 2.16kg))

‧(E4) (Trade name "062T", styrene content 23% by mass, styrene/isobutylene/styrene triblock copolymer, manufactured by Kaneka, MFR 10g/10min (measured at 230℃, 2.16kg))

‧(X1) (Trade name: "Arkon P140", aromatic fully hydrogenated petroleum resin, manufactured by Arakawa Chemical Industries, softening point 140°C, hydrogenation rate >90%)

‧(X2) (Trade name "Arkon P100", aromatic fully hydrogenated petroleum resin, manufactured by Arakawa Chemical Industries, softening point 100°C, hydrogenation rate >90%)

‧(X3) (Trade name "Arkon P125", aromatic fully hydrogenated petroleum resin, manufactured by Arakawa Chemical Industries, softening point 100°C, hydrogenation rate >90%)

‧(Y1) (Trade name "Arkon M135", aromatic partially hydrogenated petroleum resin, manufactured by Arakawa Chemical Industries, softening point 135°C, hydrogenation rate <90%)

‧(Y2) (Trade name "Arkon M100", aromatic partially hydrogenated petroleum resin, manufactured by Arakawa Chemical Industries, softening point 100°C, hydrogenation rate <90%)

‧(B1) (Trade name "CE3059", low-density polyethylene, manufactured by Sumitomo Chemical Co., Ltd., MFR 5.8g/10min (measured at 190℃, 2.16kg))

‧(B2) (Sumitomo Chemical Co., Ltd., ethylene/propylene/diene terpolymer, MFR 7.3 g/min (measured at 230°C, 2.16 kg))

‧(B3) (Commercially available block polypropylene, MFR 8.5 g/min (measured at 230°C, 2.16 kg))

‧(B4) (commercially available polyethylene particles, average particle size 10μm)

‧(B5) (Sumitomo Chemical Co., Ltd., block polypropylene, MFR 5.8 g/min (measured at 230°C, 2.16 kg))

<Modifier>

‧(R1) (commercially available silicone-based surface modifier).

‧(R2) (trade name "EP1013", α-olefin copolymer, manufactured by Mitsui Chemicals, MFR 10g/10min (measured at 230℃, 2.16kg))

‧(R3) (Trade name "XM-7080", α-olefin copolymer, manufactured by Mitsui Chemicals, MFR 7.0 g/10 min (measured at 230°C, 2.16 kg))

<Additives>

‧(Z1) (commercially available UV absorber)

(Example 1)

Prepare the constituent resins of each layer as follows.

Base material: 70% by mass of (B1) and 30% by mass of (B5) were used.

Resin layer A: 70 mass % of (E1), 15 mass % of (X1), and 15 mass % of (Y1) were used.

Resin layer B: 49 mass% (B2), 44 mass% (B3), 6 mass% (R1), and 1 mass% (B4) were used.

Next, the constituent resins of each layer were fed into respective extruders of a T-die composite film-making machine having three extruders, and the discharge amount of each extruder was adjusted so that the base material became 46.5 μm, the resin layer A became 10 μm, and the resin layer B became 3.5 μm. The layers were laminated in this order and extruded from the composite T-die at an extrusion temperature of 200°C. The film was cast onto a roll whose surface temperature was adjusted to 40°C and formed into a film shape, and was rolled up to obtain a laminated film.

Afterwards, the obtained laminated films were evaluated using the aforementioned methods.

(Example 2)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1), 10% by mass of (X1), and 20% by mass of (Y1) were used.

(Example 3)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 65 mass% of (E1), 20 mass% of (X1), and 15 mass% of (Y1) were used.

(Example 4)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 69.5 mass% of (E1), 15 mass% of (X1), 15 mass% of (Y1), and 0.5 mass% of (Z1) were used.

(Example 5)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1), 20% by mass of (X1), and 10% by mass of (Y1) were used.

(Example 6)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70 mass% of (E1), 5 mass% of (X1), and 25 mass% of (Y1) were used.

(Example 7)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70 mass % of (E1), 15 mass % of (X2), and 15 mass % of (Y2) were used.

(Example 8)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1) and 30% by mass of (X3) were used.

(Example 9)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70 mass% of (E1), 15 mass% of (X3), and 15 mass% of (Y1) were used.

(Comparison Example 1)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 80% by mass of (E2) and 20% by mass of (X2) were used.

(Comparison Example 2)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1) and 30% by mass of (X1) were used.

(Comparison Example 3)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1) and 30% by mass of (X2) were used.

(Comparative Example 4)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1) and 30% by mass of (Y1) were used.

(Comparative Example 5)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 70% by mass of (E1) and 30% by mass of (Y2) were used.

(Comparative Example 6)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 40% by mass of (E3), 20% by mass of (E4), 30% by mass of (X2), and 10% by mass of (R2) were used.

(Comparative Example 7)

A laminated film was obtained in the same manner as in Example 1 except that the resin used in the resin layer A described below was changed. Thereafter, the obtained laminated film was evaluated by the aforementioned method.

Resin layer A: 100 mass% (R3) was used.

From the results of the adhesive force ratio and the adhesive force after storage at 23°C for 24 hours, Examples 1 to 9 satisfying the requirements of the present invention are laminated films that have little change in adhesive force due to components transferred from the adherend and are not prone to floating due to cutting after lamination. On the other hand, Comparative Examples 1, 2, 6, and 7 are laminated films that have low adhesive force after storage at 23°C for 24 hours and are prone to floating; Comparative Examples 3 to 5 are laminated films that have large changes in adhesive force due to components transferred from the adherend.

[Possibility of industrial application]

When the laminated film of the present invention is used as a protective film, the adhesive force changes little due to the transfer of additives from the member to be adhered, and it is not easy to float due to cutting after bonding, so it can be suitably used as a surface protective film for building components, for example.

Claims (8)

A laminate film having a resin layer A on one surface of a substrate, wherein the glass transition temperature (Tg) of the resin layer A, the storage modulus of the resin layer A at -15°C measured at a frequency of 1 Hz and a strain of 0.01% (hereinafter, represented by G'(-15°C)), and the storage modulus of the resin layer A at 0°C measured at a frequency of 1 Hz and a strain of 0.01% (hereinafter, represented by G'(0°C)) satisfy all of the following relationships (a), (b), and (c): (a) Tg ≧ -14°C (b) G'(-15°C)/G'(0 ℃) ≤ 5.0 (c) 10MPa < G' (-15℃) < 100MPa; wherein the resin layer A comprises all of the following (d), (e), and (f): (d) styrene-based elastomer (e) at least one resin selected from the group consisting of aromatic fully hydrogenated petroleum resins with a softening point of 110℃ or more and alicyclic petroleum resins with a softening point of 110℃ or more (f) at least one resin selected from the group consisting of aromatic petroleum resins with a softening point of 110℃ or more and aromatic partially hydrogenated petroleum resins with a softening point of 110℃ or more. The laminated film of claim 1 has a resin layer B on the surface of the substrate that does not have the resin layer A. For example, in the laminated film of claim 2, the arithmetic average surface roughness Ra of the resin layer B is greater than 0.20 μm. In the laminated film of claim 1, when the resin layer A as a whole is set to 100% by mass, the resin layer A comprises the following (1) and (2): (1) at least one resin selected from the group consisting of aliphatic petroleum resins, aromatic fully hydrogenated petroleum resins and alicyclic petroleum resins: 5-25% by mass (2) at least one resin selected from the group consisting of aromatic petroleum resins, aromatic partially hydrogenated petroleum resins and terpene resins: 5-25% by mass. In the laminated film of claim 1, when the resin layer A as a whole is set to 100% by mass, the resin layer A comprises the following (3): (3) Styrene-based elastomer: 50-90% by mass. The laminated film of claim 1, wherein the resin layer A comprises components (e) and (f) which are soluble in chloroform and acetone and have a glass transition temperature (Tg_sol) of 50°C or above. For example, in the laminated film of claim 1, when the resin layer A as a whole is set to 100 mass %, the resin layer A contains 10-50 mass % of components (e) and (f) that are soluble in chloroform and acetone and have a glass transition temperature (Tg_sol) of 50°C or above. A laminated film as claimed in any one of claims 1 to 7, characterized in that it is used for protecting the surface of a decorative steel plate.