WO2013121856A1 - Adhesive sheet - Google Patents

Abstract

Provided is an adhesive sheet that: exhibits excellent weather resistance; has good initial adhesiveness, and good adhesiveness over time, enabling the adhesive sheet to exhibit excellent peelability over time after being exposed outdoors or stored at a high temperature; and has good stress mitigation properties. This adhesive sheet is obtained by forming an adhesive layer on at least one surface of a base layer. The base layer contains at least one layer selected from a whitish layer and a blackish layer. The adhesive layer comprises an adhesive containing a propylene copolymer (A) that contains, as copolymer components, propylene and an α-olefin, other than propylene, with a carbon number of two to twelve; and at least one type of resin (B) selected from an ethylene/vinyl acetate copolymer, a hydrogen additive of a C-B-C thermoplastic elastomer (where B represents a conjugated diene polymer block, and C represents a crystalline polyolefin block) having a crystallized olefin block, homo polypropylene, an ethylene/α-olefin binary copolymer, a propylene/α-olefin binary copolymer, a low-density polyethylene, a high-density polyethylene, and a linear low-density polyethylene.

Description

Adhesive sheet

The present invention relates to an adhesive sheet. The pressure-sensitive adhesive sheet of the present invention is particularly useful as a pressure-sensitive adhesive sheet having removability such as a surface protective sheet and a temporary fixing pressure-sensitive adhesive sheet for electronic parts. The pressure-sensitive adhesive sheet of the present invention, for example, when transporting, processing, curing members such as metal plates, painted metal plates, aluminum sashes, resin plates, decorative steel plates, vinyl chloride laminated steel plates, glass plates, etc. It is used for applications such as sticking to the surface for protection.

The characteristics required for the surface protective sheet include that the surface protective sheet is not lifted or peeled off after being attached to the adherend, and that the adhesive does not remain on the adherend upon peeling and removal. In particular, when it is subjected to harsh conditions such as high temperature and outdoor exposure after it is attached to the adherend and peeled off, a higher level of the above properties is required.

For this reason, as a pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer of the surface protective sheet, conventionally, acrylic copolymers have been three-dimensionally cross-linked with isocyanate compounds or methylol compounds to increase cohesion to the extent that they do not lose their tackiness. In addition, natural rubber or modified natural rubber blended with an appropriate amount of tackifier or the like is used.

The surface protective sheet having such an adhesive layer is not particularly problematic for indoor use. However, when the pressure-sensitive adhesive is mainly composed of natural rubber or modified natural rubber, or is a composition containing a tackifier or the like, the pressure-sensitive adhesive is constituted by a component having an unsaturated double bond. Therefore, when exposed to the outdoors, the component causes molecular cleavage of the component by ultraviolet light. For this reason, when peeling off a surface protection film, there exists a problem that an adhesive remains on a to-be-adhered body. Therefore, a surface protective sheet having good weather resistance is required.

In order to solve the above problems, a surface protection sheet excellent in weather resistance has been proposed in which an adhesive layer made of a hydrogenated styrene-based ABA block polymer is formed on a base film. (See Patent Document 1 and Patent Document 2). Such a sheet for surface protection using a hydrogenated styrene type ABA block polymer as an adhesive layer is a mirror-finished metal plate, a highly polar acrylic resin plate, a polycarbonate resin plate, an acrylic type or a polyester. When affixed to a coated steel sheet or the like, problems such as poor peeling occur. In particular, when affixed to a coated steel sheet coated with a paint mainly composed of an aromatic compound such as polystyrene, the above problems are likely to occur, and polar components present in the paint are substances in the adhesive layer. There arises a problem that the surface of the coated steel sheet is deformed.

There has been proposed a surface protective film having a non-adhesive property obtained by adding a polyethyleneimine and a phosphate ester surfactant to a styrene type ABA type block polymer (see Patent Document 3). However, in this surface protective film, there is a problem that a phosphoric ester surfactant as a peeling component contaminates the coated steel sheet. Furthermore, since the styrene-based ABA block polymer has a pseudo-crosslinked structure due to styrene domains, it has poor stress relaxation properties. Therefore, when a surface protective film as described above is affixed to a coated steel plate or the like, there arises a problem that a level difference due to the pasted film is likely to occur on the surface of the coated steel plate.

A surface protective film in which an ethylene / α-olefin copolymer is laminated on a base film has been proposed as a surface protective film excellent in change in adhesive strength over time (see Patent Document 4 and Patent Document 5). However, such a surface protective film has a problem that it must adhere under heating and pressurization conditions, and the adhesiveness over time is stable, while the initial adhesive strength at room temperature is 0.5 N / Since it is 25 mm or less, when it is transported after being affixed, or when it is affixed to the outside, such as a building exterior panel, there arises a problem that it peels off due to the generated wind. In particular, when such a surface protective film is applied to a metal plate having a rough surface (rough surface), an embossed coated steel plate, a resin steel plate, or the like, this low adhesive strength is a problem. It becomes.

A surface protective film having good adhesiveness using an α-olefin copolymer for the adhesive layer has been proposed (see Patent Document 6 and Patent Document 7). However, among these surface protective films, those that can obtain good adhesive strength are those containing a styrene-based ABA block polymer such as SEBS or SEPS in the adhesive layer. Due to the influence of the styrene block in the block polymer, problems of peeling failure and material transfer occur under long-term storage. Furthermore, the pressure-sensitive adhesive layer formed by the mixed system of the α-olefin copolymer and the hydrogenated styrene type ABA type block polymer is because the pressure-sensitive adhesive is mechanically kneaded at the beginning of production. Although each polymer is finely dispersed, there is a problem that when it is left outdoors at a high temperature for a long time, the finely dispersed state is destroyed with time, phase separation occurs, and adhesive residue is generated. In addition, the α-olefin copolymers used for these surface protective films have a disadvantage that they are inferior in stress relaxation because they have crystal parts, and when the surface protective film is applied to the surface of a coated steel sheet or the like, There is a problem that film sticking marks are likely to occur.

Japanese Patent Publication No. 6-89312 Japanese Patent Publication No. 5-74627 Japanese Patent Laid-Open No. 6-1958 Japanese Patent Laid-Open No. 7-258617 Japanese Patent Application Laid-Open No. 8-157791 JP-A-7-233354 Japanese Patent Laid-Open No. 11-21519

The object of the present invention is to exhibit excellent weather resistance, good initial adhesiveness, and good adhesiveness over time that can exhibit excellent peelability even after aging after outdoor exposure or storage at high temperature, and good stress. The object is to provide a pressure-sensitive adhesive sheet having relaxation properties.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed on at least one side of a base material layer, and the base material layer includes at least one layer selected from a white layer and a black layer, The adhesive layer has a propylene-based copolymer (A) containing propylene and an α-olefin having 2 to 12 carbon atoms other than propylene as a copolymerization component, an ethylene / vinyl acetate copolymer, and a crystalline olefin block. Hydrogenated product of CBC type thermoplastic elastomer (B represents conjugated diene polymer block, C represents crystalline polyolefin block), homopolypropylene, ethylene / α-olefin binary copolymer, propylene / α- At least one resin (B) selected from olefin binary copolymer, low density polyethylene, high density polyethylene, and linear low density polyethylene Consisting comprising adhesive.

In a preferred embodiment, the pressure-sensitive adhesive contains 60 to 99% by weight of the propylene copolymer (A) and 1 to 40% by weight of the resin (B).

In a preferred embodiment, the propylene-based copolymer (A) does not have an endothermic peak of 1 J / g or more as measured by a differential scanning calorimeter (DSC) in a temperature range of 0 to 200 ° C. .

In a preferred embodiment, the propylene copolymer (A) has a polystyrene-reduced weight average molecular weight (Mw) in the gel permeation chromatography (GPC) method of 2.0 × 10 ⁵ to 10.0 × 10. ⁵ , the molecular weight distribution (Mw / Mn) is 1.5 to 3.5, and the JIS-A hardness in JIS-K6253 is 20 to 50.

In a preferred embodiment, the pressure-sensitive adhesive has an MFR of 0.1 to 20 g / 10 min in JIS-K7210 (230 ° C.).

In a preferred embodiment, the pressure-sensitive adhesive sheet of the present invention is used for surface protection.

According to the present invention, it exhibits excellent weather resistance, has good initial adhesiveness and good adhesiveness over time that can exhibit excellent peelability even after outdoor exposure and storage at high temperature, and has good stress An adhesive sheet having relaxation properties can be provided.

It is a DSC chart of a propylene-type copolymer (1). It is a DSC chart of a propylene-type copolymer (2). 3 is a DSC chart of an ethylene / α-olefin binary copolymer used in a comparative example.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention (hereinafter also simply referred to as pressure-sensitive adhesive) is a propylene copolymer containing propylene and an α-olefin having 2 to 12 carbon atoms other than propylene as a copolymerization component. It contains a polymer (A). The α-olefin having 2 to 12 carbon atoms other than propylene may be only one kind or two or more kinds.

The pressure-sensitive adhesive containing the propylene-based copolymer (A) has a good initial pressure-sensitive adhesiveness, and can suppress the adhesion increase with respect to a metal plate and a coated steel plate. Good peelability. In addition, since the propylene-based copolymer (A) has substantially no crystal part, it has excellent stress relaxation properties, and the stress generated from the base material is relaxed by the adhesive layer. No film sticking marks. Further, the propylene-based copolymer (A) has a good cohesive force and can be peeled well even when left at high temperature. The propylene-based copolymer (A) preferably has an atactic structure in which the α-olefin having 2 to 12 carbon atoms other than propylene and propylene is oriented.

As the α-olefin having 2 to 12 carbon atoms other than propylene, any appropriate α-olefin can be adopted. Specific examples of the α-olefin having 2 to 12 carbon atoms other than propylene include, for example, ethylene and α-olefin having 4 to 12 carbon atoms. Examples of the α-olefin having 4 to 12 carbon atoms include butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, dodecene-1, 4-methyl- Pentene-1,4-methyl-hexene-1. The α-olefin having 4 to 12 carbon atoms is preferably butene-1, pentene-1, hexene-1, heptene-1, or octene-1.

The proportion of each component constituting the propylene-based copolymer (A) can be appropriately adjusted depending on the application.

In order to obtain good tackiness and removability, the propylene content in the propylene-based copolymer (A) is preferably 40 to 95% by weight, more preferably 60 to 90% by weight, more preferably 76 to 85% by weight. In this case, ethylene and α-olefin having 4 to 12 carbon atoms are preferably used in combination as the α-olefin having 2 to 12 carbon atoms other than propylene in order to develop good low-temperature adhesiveness. In this case, the content ratio of the α-olefin having 4 to 12 carbon atoms and ethylene in the propylene-based copolymer is a weight ratio of the monomer composition, and α-olefin having 4 to 12 carbon atoms: ethylene is preferable. The ratio is 1: 1 to 40: 1, more preferably 2: 1 to 30: 1.

In order to obtain good wettability and light release properties, the propylene content in the propylene-based copolymer (A) is preferably 1 to 40% by weight, more preferably 2 to 2% by weight ratio of the monomer composition. 30% by weight, more preferably 3 to 20% by weight. In this case, in order to develop good light peelability, ethylene and α-olefin having 4 to 12 carbon atoms are preferably used in combination as α-olefin having 2 to 12 carbon atoms other than propylene. In this case, the content ratio of the α-olefin having 4 to 12 carbon atoms and ethylene in the propylene-based copolymer is a weight ratio of the monomer composition, and α-olefin having 4 to 12 carbon atoms: ethylene is preferable. The ratio is 1: 1 to 1:20, more preferably 1: 2 to 1:10.

Arbitrary appropriate methods can be employ | adopted as a manufacturing method of a propylene-type copolymer (A). Examples of such a method include solution polymerization, slurry polymerization, and gas phase polymerization. More specifically, for example, it can be produced by polymerization using a catalyst described in JP-A-11-80233.

The propylene copolymer (A) preferably does not have an endothermic peak of 1 J / g or more as measured by a differential scanning calorimeter (DSC) in the temperature range of 0 to 200 ° C. Propylene-based copolymer (A) exhibits superior adhesiveness by not having an endothermic peak of 1 J / g or more in a temperature range of 0 to 200 ° C. with a differential scanning calorimeter (DSC). And can exhibit more excellent stress relaxation properties. More preferably, the propylene-based copolymer (A) does not have an endothermic peak of 0.5 J / g or more as measured by a differential scanning calorimeter (DSC) in a temperature range of 0 to 200 ° C.

Note that the propylene copolymer (A) does not have an endothermic peak of 1 J / g or more in the measurement in the temperature range of 0 ° C. to 200 ° C. with a differential scanning calorimeter (DSC). When the DSC analysis of the propylene-based copolymer (A) is performed by the method (conditions) shown in the examples, an endothermic peak of 1 J / g or more that is considered to be based on the melting of crystals in the temperature range of 0 ° C. to 200 ° C. Say that is not confirmed.

The weight average molecular weight (Mw) in terms of polystyrene in the gel permeation chromatography (GPC) method of the propylene copolymer (A) is preferably 2.0 × 10 ⁵ to 10.0 × 10 ⁵ , more It is preferably 2.0 × 10 ⁵ to 9.0 × 10 ⁵ , and more preferably 2.5 × 10 ⁵ to 8.0 × 10 ⁵ . When the said weight average molecular weight (Mw) is 2.0 * 10 < ⁵ > or more, cohesion force is favorable and it can peel favorably without adhesive residue. Moreover, in the case of 10.0 * 10 < ⁵ > or less, the moldability in the case of extruding the adhesive containing a propylene-type copolymer (A) is favorable, for example.

The molecular weight distribution (Mw / Mn) of the propylene copolymer (A) is preferably 1.5 to 3.5, more preferably 1.5 to 3.0. When the molecular weight distribution (Mw / Mn) is 3.5 or less, the generated low molecular weight component can be prevented from causing poor peeling, and the high molecular weight component is present as a foreign substance in the adhesive layer. It can suppress that it becomes a cause of a defect.

The JIS-A hardness in JIS-K6253 of the propylene copolymer (A) is preferably 20 to 50, more preferably 22 to 40, and further preferably 25 to 38. If the JIS-A hardness falls within the above range, the film is soft and hardly causes film sticking.

In the present invention, the pressure-sensitive adhesive is an ethylene / vinyl acetate copolymer, a CBC type thermoplastic elastomer having a crystalline olefin block (B represents a conjugated diene polymer block, and C represents a crystalline polyolefin block). Additive, at least one resin selected from homopolypropylene, ethylene / α-olefin binary copolymer, propylene / α-olefin binary copolymer, low density polyethylene, high density polyethylene, and linear low density polyethylene (B) is contained.

The pressure-sensitive adhesive in the present invention contains the propylene copolymer (A) and the resin (B), whereby the melt viscosity is lowered and the film-forming property at the time of extrusion is improved. Therefore, even when the propylene-based copolymer (A) that is difficult to be extruded is used, the pressure-sensitive adhesive sheet can be produced by co-extrusion of the base material layer and the pressure-sensitive adhesive layer. Moreover, since resin (B) is excellent in cohesive force within the use temperature range, it is possible to suppress a decrease in cohesive force of the propylene-based copolymer (A) at high temperatures. Further, the propylene copolymer (A) is stable over time by adjusting the monomer composition so as to be finely dispersed in the resin (B), and no adhesive residue is generated.

The MFR of the resin (B) in JIS-K7210 (230 ° C.) is preferably 1 to 30 g / 10 min, more preferably 3 to 20 g / 10 min, from the viewpoint of improving the film formability.

The vinyl acetate content in the ethylene / vinyl acetate copolymer is preferably from 5 to 42% by weight, more preferably from the viewpoint of reduction in cohesive strength of the adhesive layer at high temperatures and poor peeling due to the introduction of vinyl acetate groups. 5 to 25% by weight. When the vinyl acetate content in the ethylene / vinyl acetate copolymer exceeds 42% by weight, the cohesive force is poor at high temperatures such as in summer, and the ethylene / vinyl acetate copolymer may cause adhesive residue.

Examples of the ethylene / α-olefin binary copolymer include ethylene / α comprising an ethylene component and an α-olefin such as propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, and the like. -Olefin binary copolymers. Among such ethylene / α-olefin binary copolymers, ethylene / propylene block copolymers and random copolymers are preferred.

As the propylene / α-olefin binary copolymer, for example, a propylene / α-olefin comprising a propylene component and an α-olefin such as butene-1, pentene-1, hexene-1, heptene-1, octene-1 A binary copolymer is mentioned.

Specific examples of these ethylene / α-olefin binary copolymers and propylene / α-olefin binary copolymers include, for example, trade names “Novatech PP” manufactured by Nippon Polychem Co., Ltd., and Idemitsu Petrochemical Co., Ltd. The product name “Moretech”, the product name “Affinity” manufactured by Dow Chemical Company, the product name “Tuffmer” manufactured by Mitsui Chemicals, and the like are available.

The hydrogenated CBC type thermoplastic elastomer has not only the effect of improving the film-forming property of the pressure-sensitive adhesive, but also the CB— constituting the propylene copolymer (A) and the resin (B). It can also be used as a compatibilizer with other resins other than the hydrogenated product of C-type thermoplastic elastomer.

Examples of hydrogenated CBC type thermoplastic elastomers include crystalline olefin / ethylene / butylene / crystalline olefin block copolymer (CEBC) and crystalline olefin / ethylene / propylene / crystalline olefin block copolymer. A polymer (CEPC) etc. are mentioned. As the C block of CEBC, a polybutadiene block in which the 1,2-vinyl structure is controlled to 25% by weight or less is preferable, and as the B block, a polybutadiene block in which the 1,2-vinyl structure is controlled to 25 to 95% by weight Is preferred. Further, as the C block of CEPC, a polybutadiene block in which the 1,2-vinyl structure is controlled to 20% by weight or less is preferable, and as the B block, the 1,4-vinyl structure is controlled to 40 to 99% by weight. Polyisoprene blocks are preferred. As the CBC type thermoplastic elastomer, specifically, for example, trade name “Dynalon 6200P” manufactured by JSR Corporation is available. When a hydrogenated CBC type thermoplastic elastomer is added for the purpose of a compatibilizing agent, the content of hydrogenated CBC type thermoplastic elastomer is determined by the propylene copolymer weight. It is preferably 30% by weight or less, more preferably 1 to 20% with respect to a mixture comprising the union (A) and a resin other than the hydrogenated product of the CBC type thermoplastic elastomer constituting the resin (B). % By weight. When the content exceeds 30% by weight, the tackiness is lowered, which may cause peeling.

The pressure-sensitive adhesive in the present invention comprises a propylene-based copolymer (A) and a resin (B). The pressure-sensitive adhesive in the present invention preferably contains 60 to 99% by weight of the propylene copolymer (A) and 1 to 40% by weight of the resin (B).

The pressure-sensitive adhesive in the present invention has a good film forming effect and agglomeration when the content of the resin (B) is 1% by weight or more in the total amount of the propylene copolymer (A) and the resin (B). It can have an effect of improving the property. Moreover, by adjusting the content of the resin (B) to 40% by weight or less in the total amount of the propylene-based copolymer (A) and the resin (B), peeling due to a decrease in adhesiveness and a decrease in stress relaxation properties. The film sticking marks due to can be lost.

In the total amount of the propylene copolymer (A) and the resin (B), the content of the resin (B) is more preferably 5 to 30% by weight, still more preferably 10 to 20% by weight.

In the total amount of the propylene-based copolymer (A) and the resin (B), the content of the propylene-based copolymer (A) is more preferably 70 to 95% by weight, still more preferably 80 to 90% by weight. is there.

The ratio of the total amount of the propylene copolymer (A) and the resin (B) in the pressure-sensitive adhesive in the present invention is preferably 70% by weight or more, more preferably 80% by weight or more.

The pressure-sensitive adhesive in the present invention is a styrene-ethylene-butylene copolymer-styrene copolymer (in addition to the propylene-based copolymer, as long as the purpose of the present invention is not impaired for the purpose of improving the adhesiveness). Hydrogenated styrene type ABA type block polymer such as SEBS) and styrene-ethylene / propylene copolymer-styrene copolymer (SEPS); copolymer of styrene-ethylene-butylene copolymer (SEB) ) And styrene-ethylene / propylene copolymer (SEP) hydrogenated styrene AB block polymer; styrene-ethylene / butylene copolymer-olefin crystal block polymer copolymer (SEBC) Hydrogenated styrene-based ABC type block polymer such as); Random copolymerization of styrene and diene hydrocarbon Hydrogenated products; and it may contain. These may be only one type or two or more types.

The content ratio of the block polymer having these styrene components can be adjusted as appropriate, but if the content ratio increases, the propylene-based copolymer is adversely affected in terms of adhesion increase, material transferability, and stress relaxation properties. The content is preferably 0 to 40% by weight, more preferably 0 to 20% by weight, still more preferably 0 to 10% by weight based on the total amount of (A) and the resin (B). When the content ratio of the block polymer having these styrene components exceeds 40% by weight with respect to the total amount of the propylene-based copolymer (A) and the resin (B), the stress relaxation property is impaired, or the styrene component There is a risk that a peeling failure due to the influence of the surface is likely to occur.

The pressure-sensitive adhesive in the present invention is, for example, a softener, an olefin resin, a silicone polymer, a liquid acrylic copolymer, a tackifier, an anti-aging agent, a hindered amine, for the purpose of controlling the adhesive properties and the like. Additives such as system light stabilizers, UV absorbers, polyethyleneimine, fatty acid amides, phosphate esters, fillers and pigments (for example, calcium oxide, magnesium oxide, silica, zinc oxide, titanium oxide, etc.) are added as appropriate be able to.

For the adhesive in the present invention, for example, corona discharge treatment, ultraviolet irradiation treatment, flame treatment, plasma treatment, sputter etching treatment, and other surface treatments for the purpose of adhesion control and pasting workability, etc., as necessary. It can also be applied.

The pressure-sensitive adhesive in the present invention may contain a softening agent for improving the adhesive strength. As the softening agent, for example, low molecular weight polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene, and derivatives thereof can be used. Examples of derivatives are those having an OH group or COOH group at one or both ends, such as hydrogenated polybutadiene diol, hydrogenated polybutadiene monool, hydrogenated polyisoprene diol, and hydrogenated polyisoprene monool. . As such a softening agent, a hydrogenated product of a diene polymer such as hydrogenated polybutadiene or hydrogenated isoprene or an olefinic softening agent is particularly preferable for the purpose of suppressing an improvement in adhesion to an adherend. As such a softening agent, specifically, trade name “Kuraprene LIR-200” manufactured by Kuraray Co., Ltd. is available. Only one kind of such softener may be used, or two or more kinds may be used. The content of the softening agent can be appropriately set, but is preferably 0 to 50% by weight, more preferably 0 to 40% by weight, based on the total amount of the propylene-based copolymer (A) and the resin (B). %, More preferably 5 to 20% by weight. If the content of the softener exceeds 50% by weight with respect to the total amount of the propylene-based copolymer (A) and the resin (B), the adhesive residue at high temperature or outdoor exposure may become remarkable.

The molecular weight of the softening agent can be set appropriately, but the number average molecular weight is preferably 5000 to 100,000, more preferably 10,000 to 50,000. If the number average molecular weight of the softening agent is 5000 or less, there is a risk of causing substance transfer to the adherend or heavy peeling. If the number average molecular weight of the softening agent is 100,000 or more, the effect of improving the adhesive strength is poor. .

The pressure-sensitive adhesive in the present invention may contain a tackifier for improving the adhesive strength. The content ratio of the tackifier is from the point of improving the adhesive force by avoiding the occurrence of the adhesive residue problem due to the decrease in cohesive force, with respect to the total amount of the propylene-based copolymer (A) and the resin (B), It is preferably 50% by weight or less, more preferably 30% by weight or less, and further preferably 5 to 20% by weight.

Examples of the tackifier include petroleum resins such as aliphatic and aromatic, aliphatic / aromatic copolymer systems and alicyclic systems, coumarone indene resins, terpene resins, terpene phenol resins, and the like. Any appropriate tackifier such as a polymerized rosin resin, (alkyl) phenol resin, xylene resin, or hydrogenated resin thereof can be used. Only one type of tackifier may be used, or two or more types may be used. As the tackifier, a hydrogenated tackifier is preferable from the viewpoint of peelability and weather resistance. Also, a blend of a tackifier and an olefin resin is commercially available, and this may be used.

The MFR of the pressure sensitive adhesive in JIS-K7210 (230 ° C.) is preferably 0.1 to 20 g / 10 min, more preferably 0.2 to 15 g / 10 min, and further preferably 0.3 to 10 g / 10 min. is there. If the MFR of the pressure sensitive adhesive in JIS-K7210 (230 ° C.) is 0.1 g / 10 min or more, the pressure sensitive adhesive in the present invention can be easily extruded and stable thickness accuracy can be obtained. If the MFR of the pressure sensitive adhesive in JIS-K7210 (230 ° C.) is 20 g / 10 min or less, inflation molding can be easily performed.

Formation of the pressure-sensitive adhesive in the present invention is, for example, a method of applying a solution of a pressure-sensitive adhesive or a hot melt to a base material, or transferring a pressure-sensitive adhesive layer applied and formed on a separator according to the method. Method, Method of Extruding and Forming Adhesive Layer Forming Material on Supporting Base Material, Method of Co-Extruding Base Layer Forming Material and Adhesive Layer Forming Material in Two Layers or Multiple Layers, Adhesive on Substrate Layer Examples thereof include a method of laminating a single layer, a method of laminating an adhesive layer together with a laminate layer, a method of laminating an adhesive layer and a supporting substrate forming material such as a film or a laminate layer in two layers or multiple layers, and the like. Among these methods, the method of co-extrusion molding of the adhesive layer forming material together with the base material layer forming material made of a thermoplastic resin by two or multiple layers by an inflation method or a T-die method, productivity, cost, etc. From the point of view, it is preferable.

The thickness of the adhesive layer is appropriately adjusted according to the adhesive strength and the like. The thickness of the adhesive layer is preferably 3 to 50 μm, more preferably 5 to 40 μm, and still more preferably 7 to 35 μm.

If necessary, the adhesive layer can be protected by temporarily attaching a separator or the like until it is put to practical use.

In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer is formed on at least one side of the base material layer.

The thickness of the base material layer is preferably 5 to 300 μm, more preferably 20 to 150 μm. As the ultraviolet transmittance of the base material layer, the transmittance at a wavelength of 365 nm is preferably 5% or less, more preferably 1% or less.

Examples of the material of the base material layer include polyesters; polyamides, propylene polymers such as block systems, random systems, and graft systems using homopolymers (homopolypropylene) or ethylene components as copolymerization components; low density polyethylene, high density polyethylene And ethylene-based polymers such as linear low-density polyethylene and ultra-low-density polyethylene; olefin-based polymers such as ethylene / propylene copolymer; paper; metal films; The material of the base material layer may be only one kind or two or more kinds. The material of the base layer is preferably a polyester; a polyamide, a single system (homopolypropylene) or a propylene polymer such as a block system, a random system, or a graft system having an ethylene component as a copolymer component; a low density polyethylene, a high density Plastic films such as polyethylene polymers such as polyethylene, linear low density polyethylene, and ultra low density polyethylene; olefin polymers such as ethylene / propylene copolymer;

When a plastic film is selected as the material for the base material layer, for the purpose of preventing deterioration, for example, a light stabilizer such as an antioxidant, an ultraviolet absorber, a hindered amine light stabilizer, an antistatic agent, a filler or a pigment. (Carbon black, calcium oxide, magnesium oxide, silica, zinc oxide, titanium oxide, etc.) may be contained.

Examples of the antioxidant include hindered phenol antioxidants, phosphorus processing heat stabilizers, lactone processing heat stabilizers, and sulfur heat resistance stabilizers. The antioxidant is preferably 5% by weight or less, more preferably 3% by weight with respect to the base resin as the material of the base layer (when the base layer is a blend, the blend is the base resin). % Or less, more preferably 0.1 to 0.5% by weight.

Examples of UV absorbers include benzotriazole UV absorbers, triazine UV absorbers, and benzophenone UV absorbers. The ultraviolet absorber is preferably 5% by weight or less, more preferably 3% by weight based on the base resin as the material of the base layer (when the base layer is a blend, the blend is the base resin). % Or less, more preferably 0.1 to 1% by weight.

Examples of light stabilizers include hindered amine light stabilizers and benzoate light stabilizers. The light stabilizer is preferably 5% by weight or less, more preferably 3% by weight based on the base resin as the material of the base layer (when the base layer is a blend, the blend is the base resin). % Or less, more preferably 0.1 to 1% by weight.

The base material layer includes at least one layer selected from a white layer and a black layer. Thereby, it can be set as the adhesive sheet excellent in weather resistance.

The white layer is a layer showing a white color tone. For example, the whiteness specified by JIS-L-1015 is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, Particularly preferably, it is 85% or more. The white layer preferably contains a white pigment. Any appropriate white pigment can be adopted as the white pigment. An example of such a white pigment is titanium oxide. When the white layer contains a white pigment, the content is preferably 0.1 to 50% by weight, more preferably 1 to 30% by weight, based on the resin component forming the white layer. More preferably, it is 5 to 20% by weight.

The resin component forming the white layer includes the material of the base material layer, preferably a polyolefin resin, more preferably at least one selected from a propylene polymer and an ethylene polymer, and more preferably Is an ethylene-based polymer having a density of 0.88 to 0.93 g / cm ³ . Specifically as a resin component which forms a white type | system | group layer, a polypropylene, a low density polyethylene (LDPE), and a linear low density polyethylene (LLDPE) are mentioned preferably. The content of the polyolefin resin in the white layer is preferably 60% by weight or more, more preferably 70% by weight or more, further preferably 80% by weight or more, particularly preferably 85% by weight or more, and most preferably 90% by weight. That's it. Such polyolefin resin may use only 1 type, and may use 2 or more types.

Any appropriate thickness can be adopted as the thickness of the white layer depending on the purpose. Such a thickness is preferably 1 to 50 μm, more preferably 3 to 40 μm, still more preferably 5 to 30 μm, and particularly preferably 10 to 30 μm.

The black layer is a layer showing a black color tone. The black layer preferably contains a black pigment. Any appropriate black pigment can be adopted as the black pigment. An example of such a black pigment is carbon black. When the black layer contains a black pigment, the content is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the resin component forming the black layer. More preferably, it is 0.5 to 3% by weight.

The resin component forming the black layer includes the material of the base material layer, preferably a polyolefin resin, more preferably at least one selected from a propylene polymer and an ethylene polymer, and more preferably Is an ethylene-based polymer having a density of 0.88 to 0.93 g / cm ³ . Specifically as a resin component which forms a black type layer, a polypropylene, low density polyethylene (LDPE), and linear low density polyethylene (LLDPE) are mentioned preferably. The content of the polyolefin resin in the black layer is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, particularly preferably 85% by weight or more, and most preferably 90% by weight. That's it. Such polyolefin resin may use only 1 type, and may use 2 or more types.

Any appropriate thickness can be adopted as the thickness of the black layer according to the purpose. Such a thickness is preferably 1 to 100 μm, more preferably 5 to 70 μm, still more preferably 10 to 60 μm, and particularly preferably 20 to 50 μm.

For the surface where the adhesive layer of the base material layer is not provided, for the purpose of forming a wound body that can be easily rewound, a fatty acid amide, polyethyleneimine, or the like is added to perform mold release treatment, It is also possible to provide a coat layer made of an appropriate release agent such as a long chain alkyl type or fluorine type.

The pressure-sensitive adhesive sheet of the present invention can be produced by any appropriate method. Preferably, from the viewpoint of productivity, cost, etc., the adhesive layer forming material is co-extruded in two or multiple layers by the inflation method or the T-die method together with the base material layer forming material made of thermoplastic resin. is there. When the base material layer includes two layers of a white layer and a black color layer, there are at least two kinds of forming materials for forming the base material layer. Therefore, the pressure-sensitive adhesive sheet of the present invention has two kinds of forming the base material layer. Using the above-described forming material and the forming material for forming the adhesive layer, the base material layer and the adhesive layer are formed in multiple layers by coextrusion. The configuration of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and “white-based layer / adhesive layer”, “black-based layer / adhesive layer”, “white-based layer / black-based layer / adhesive layer”, “black” Any structure of “system layer / white system layer / adhesion layer” can be employed. Moreover, as a base material layer, it can also be set as the layer structure of 3 or more layers which formed layers other than a black-type layer and a white-type layer. Specifically, a configuration such as “transparent resin layer / white color layer / black color layer / adhesive layer” may be employed. Furthermore, the thickness of the white layer and the black layer may be the same, and the thickness may be different (a white layer is thinner than the black layer, and a white layer is thicker than the black layer). May be.

The pressure-sensitive adhesive sheet of the present invention can be preferably used for applications requiring removability and temporary sticking properties, and in particular, metal plates, painted metal plates, aluminum sashes, resin plates, decorative steel plates, vinyl chloride laminated steel plates. When transporting, processing, curing members such as glass plates, etc., such as adhesive sheets, electronic parts, etc. that temporarily protect parts of surface protection sheets and home appliances that are attached to the surfaces of these members to protect them It can be suitably used as a pressure-sensitive adhesive sheet having removability such as a pressure-sensitive adhesive sheet for the purpose of simplification during production.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

(Propylene copolymer)
Table 1 shows the characteristic values of the propylene-based copolymer used.

In Table 1, P: B: E represents propylene: butene-1: ethylene. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) were determined by GPC method (column: manufactured by Tosoh Corp., TSKgel GMH-H (S) × 2, solvent: tetrahydrofuran, converted to polystyrene). It is a value measured according to JIS-K6253.

A DSC chart of the propylene-based copolymer (1) is shown in FIG. 1, and a DSC chart of the propylene-based copolymer (2) is shown in FIG. Neither propylene-based copolymer (1) nor (2) has an endothermic peak of 1 J / g or more at 0 ° C. to 200 ° C. No melting point or heat of fusion was observed. The DSC chart uses a differential scanning calorimeter (manufactured by Seiko Instruments Inc., DSC2000). The measurement conditions are temperature: −40 to 200 ° C., atmospheric gas: nitrogen (200 ml / min), rate of temperature increase: 10 ° C./min. It was measured by. The temperature increase and decrease processes during the measurement were performed at 10 ° C./min.

[Example 1]
As a material for forming the adhesive layer, a hydrogenated petroleum resin (1), a hydrogenated petroleum resin (1) and a mixture of 20% by weight of an ethylene / vinyl acetate copolymer (manufactured by Tosoh Corporation, Ultrasen 633) Carbon black (carbon black “# 45” manufactured by Mitsubishi Chemical Corporation) was used as a material for forming the black base layer of the base material intermediate layer by using an adhesive composition to which 17% by weight of Alcon P-125) manufactured by Arakawa Chemical Co., Ltd. was added. Using low density polyethylene (Tosoh Corp., Petrocene 172) to which 1 wt% was added, white pigment (Daiichi Seika Co., Ltd., HCM2035W) 20 wt% was added as a material for forming the white surface layer of the substrate surface layer. Each of the low-density polyethylenes was coextruded by an inflation molding method to obtain a surface protective sheet (1).
The thickness of the surface protective sheet (1) was white layer / black layer / adhesive layer = 30 μm / 30 μm / 20 μm.

[Example 2]
In Example 1, a pressure-sensitive adhesive composition comprising 80% by weight of a propylene-based copolymer (1) and 20% by weight of linear low-density polyethylene (Idemitsu Petrochemical Co., Ltd., Idemitsu LL1014G) is used as a material for forming the pressure-sensitive adhesive layer. Except having used, it carried out similarly to Example 1 and obtained the surface protection sheet (2).
The thickness of the surface protective sheet (2) was white layer / black layer / adhesive layer = 25 μm / 25 μm / 15 μm.

Example 3
As a material for forming the adhesive layer, a hydrogenated terpene resin (manufactured by Yasuhara Chemical Co., Ltd.) is used with respect to a mixture of 90% by weight of propylene copolymer (1) and 10% by weight of random polypropylene (manufactured by Idemitsu Petrochemical Co., Ltd., F-744NP). , Clearon P-105) Using a pressure-sensitive adhesive composition to which 9% by weight was added, a fatty acid amide was added to low-density polyethylene (Petrocene 172, manufactured by Tosoh Corporation) as a material for forming a white base layer of the base material surface layer. 7% by weight, white pigment (manufactured by Dainichi Seika Co., Ltd., HCM2035W) 20% by weight, and polypropylene (Sumitomo Chemical Co., Ltd., Noblen AD571) as a material for forming the black base layer of the base material intermediate layer UV absorber 0.3% by weight (manufactured by Ciba Specialty Chemicals, Tinuvin), light stabilizer 0.22% by weight (Ciba Specialty) Chemicals Co., Kimasorb), carbon black (Mitsubishi Chemical, carbon black “# 45”) 1 wt% added material, each was co-extruded in three layers by T-die molding method, surface protection sheet (3 )
The thickness of the surface protective sheet (3) was white layer / black layer / adhesive layer = 15 μm / 30 μm / 15 μm.

Example 4
In Example 1, as a material for forming the adhesive layer, water was used with respect to 90% by weight of the propylene copolymer (2) and 10% by weight of propylene / α-olefin copolymer (Mitsui Chemicals, Toughma-XR107L). A surface protective sheet (4) was obtained in the same manner as in Example 1 except that an adhesive composition containing 9% by weight of an additive petroleum resin (Arakawa Chemical Co., Ltd., Alcon P-125) was used.
The thickness of the surface protective sheet (4) was white layer / black layer / adhesive layer = 30 μm / 30 μm / 15 μm.

Example 5
In Example 3, as an adhesive layer forming material, propylene copolymer (2) 80% by weight and crystalline olefin / ethylene / butylene / crystalline olefin block copolymer (manufactured by JSR, Dynalon 6200P) 20% by weight A surface protective sheet (5) was obtained in the same manner as in Example 3 except that the pressure-sensitive adhesive composition was used.
The thickness of the surface protective sheet (5) was white layer / black layer / adhesive layer = 15 μm / 30 μm / 15 μm.

[Reference Example 1]
In Example 1, only the propylene copolymer (2) was used as the material for forming the adhesive layer, but extrusion molding was impossible. Therefore, a toluene solution of the propylene-based copolymer (2) was applied as a pressure-sensitive adhesive to a low-density polyethylene film having a thickness of 100 μm and dried to form a pressure-sensitive adhesive layer to obtain a surface protective sheet (R1). The thickness of the adhesive layer was adjusted to 20 μm.

[Comparative Example 1]
A surface protective sheet was prepared in the same manner as in Example 1 except that an ethylene / α-olefin binary copolymer (manufactured by DuPont, Affinity PF-1140) was used as a material for forming the adhesive layer in Example 1. (C1) was obtained.
The ethylene / α-olefin binary copolymer used as a material for forming the adhesive layer had an endothermic peak of 95.7 ° C. (40.5 J / g) under the above measurement conditions. The DSC chart is shown in FIG.

[Comparative Example 2]
In Example 1, the surface protective sheet was prepared in the same manner as in Example 1 except that an ethylene / α-olefin binary copolymer (Esprene 201, manufactured by Sumitomo Chemical Co., Ltd.) was used as the material for forming the adhesive layer. (C2) was obtained.
The ethylene / α-olefin binary copolymer used as the material for forming the adhesive layer did not have an endothermic peak under the above measurement conditions.

[Comparative Example 3]
A surface protective sheet (C3) was obtained in the same manner as in Example 1 except that carbon black and white pigment were not added to the base material layer in Example 1.

The following evaluations were performed on the surface protective sheets obtained in the examples and comparative examples. The evaluation results are shown in Table 2.

(Initial adhesive strength)
The surface protective sheet was attached to a metal plate coated with polyester melamine by two reciprocating pressure bonding with a 2 kg roller, and then the adhesive strength (N / 25 mm) after standing at 23 ° C. for 1 hour was measured.
Measurement conditions: 23 ° C., 65% RH
Peeling condition: tensile speed 300mm / min, 180 degree peel

(Adhesive strength over time)
After the surface protective sheet was attached to a metal plate coated with polyester melamine by two reciprocating pressure bonding with a 2 kg roller, the adhesive strength (N / 25 mm) after standing at 80 ° C. for 30 days was measured.
Measurement conditions: 23 ° C., 65% RH
Peeling condition: tensile speed 300mm / min, 180 degree peel

(Stress relaxation)
The surface protection sheet is attached to a metal plate coated with polyester melamine so that bubbles (one circle with a diameter of 2 cm) and wrinkles (length 5 cm, height 5 mm) are generated, and left at 80 ° C. for 30 days. When the product was peeled, the presence or absence of adhesive residue (cohesiveness) on the metal plate and the presence or absence of film sticking (marking property) were visually observed. In addition, the film was left to stand for 14 days in an environment of 60 ° C./95% RH, then peeled off, and the presence or absence of thinning of the coating film (observation of the reduction in the skin due to substance transfer at the pasting part) after 24 hours at room temperature was visually observed. .

(MFR of adhesive layer)
MFR (g / 10 min) in JIS-K7210 (230 ° C.) was measured.

(Formability)
It was observed whether inflation moldability was possible.

(Measurement of weather resistance)
The surface protection sheet was cut into a strip shape having a width of 20 mm to prepare an evaluation sample. This sample was pressed against a SUS430BA plate by reciprocating a 2 kg roller, and then put into a sunshine carbon weather meter (product of Suga Test Instruments Co., Ltd.) for 1000 hours, and then from one end of the sample to a length of 100 mm Was peeled in the 180 ° direction at a tensile speed of 0.3 m / min.
The above results were evaluated according to the following criteria.
○: The sample was not broken and could be peeled off very well.
X: The sample was broken in the middle due to deterioration of the substrate, or the adhesive remained on the adherend and was contaminated.

From Table 2, in the examples, it shows excellent weather resistance, has initial adhesive strength, and also has a small increase in adhesive strength over time, has a stable adhesive strength over time, and has good peelability. It can be seen that the pressure-sensitive adhesive layer has stress relaxation properties and is excellent in all of cohesiveness and substance transferability at high temperatures. The pressure-sensitive adhesive layer of the example has a favorable MFR value for inflation molding and can be accommodated under normal inflation molding conditions. However, in Reference Example 1, the MFR value is small and the temperature of the resin is raised to 300 ° C. Inflation molding was attempted, but formation of a hole or the like at the time of blow or an abnormal pressure in the extruder occurred, and the film could not be formed stably.

The pressure-sensitive adhesive sheet of the present invention, particularly the surface protective sheet, is used when, for example, transporting, processing, curing members such as a metal plate, a painted metal plate, an aluminum sash, a resin plate, a decorative steel plate, a vinyl chloride laminated steel plate, a glass plate, etc. In addition, it is used for applications such as attaching to the surface of these members for protection.

Claims (6)

An adhesive sheet in which an adhesive layer is formed on at least one side of the base material layer,
The base material layer includes at least one layer selected from a white layer and a black layer,
The adhesive layer comprises a propylene copolymer (A) containing propylene and an α-olefin having 2 to 12 carbon atoms other than propylene as a copolymerization component, an ethylene / vinyl acetate copolymer, and a crystalline olefin block. Hydrogenated product of CBC type thermoplastic elastomer (B represents conjugated diene polymer block, C represents crystalline polyolefin block), homopolypropylene, ethylene / α-olefin binary copolymer, propylene / α -An adhesive comprising at least one resin (B) selected from olefin binary copolymer, low density polyethylene, high density polyethylene, and linear low density polyethylene,
Adhesive sheet. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive contains 60 to 99% by weight of the propylene copolymer (A) and 1 to 40% by weight of the resin (B). The propylene-based copolymer (A) does not have an endothermic peak of 1 J / g or more as measured by a differential scanning calorimeter (DSC) in a temperature range of 0 to 200 ° C. Adhesive sheet. The propylene copolymer (A) has a polystyrene-reduced weight average molecular weight (Mw) in the gel permeation chromatography (GPC) method of 2.0 × 10 ⁵ to 10.0 × 10 ⁵ and a molecular weight distribution. The pressure-sensitive adhesive sheet according to claim 1, wherein (Mw / Mn) is 1.5 to 3.5, and JIS-A hardness in JIS-K6253 is 20 to 50. The pressure-sensitive adhesive sheet according to claim 1, wherein the MFR of the pressure-sensitive adhesive in JIS-K7210 (230 ° C) is 0.1 to 20 g / 10 min. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, which is used for surface protection.

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