JP5537509B2 - Adhesive film - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive film having a pressure-sensitive adhesive layer having an appropriate pressure-sensitive adhesive force (peeling strength) and little dependency on a peeling rate when adhered to the surface of an article such as a synthetic resin plate, a decorative plywood, a metal plate, and a coated steel plate.

An adhesive film comprising a base material layer made of a thermoplastic resin such as a polyolefin-based resin, and an adhesive layer made of a low crystalline or amorphous polymer such as EVA or low density polyethylene; An adhesive film comprising an adhesive layer made of an elastomer such as a styrene block copolymer or a hydrogenated product thereof is known. These pressure-sensitive adhesive films change with time at high temperatures, and as a result, the adhesive force increases, making it difficult to peel off from the adherend, or the pressure-sensitive adhesive remains on the surface of the adherend after peeling, The variation in the adhesion performance is large, the adhesion performance often changes over time, and it is difficult to control it within a certain range. That is, the pressure-sensitive adhesive film is usually stored and distributed in a state where a film having a length of several hundred meters to several thousand meters is rolled up. When the pressure-sensitive adhesive film is rewound from the roll shape, blocking occurs between the base material layer and the pressure-sensitive adhesive layer, and in some cases, the adhesive film may move to the surface on the base material layer side where the pressure-sensitive adhesive layer contacts. On the other hand, in order to facilitate rewinding from the roll, it is also known to add a release agent or the like to the base material layer, but the release agent moves to the adhesive layer to reduce the adhesive strength, and the base material layer The slipping property may become too large.

As a method for improving them, a surface protective film that suppresses an increase in unwinding force by using a resin mainly composed of polyethylene on the surface of a base material layer is disclosed (for example, Patent Document 1). According to this document, when the main component of the pressure-sensitive adhesive layer is a resin whose main component is polypropylene, and the base material layer is a polypropylene-based resin, it has a high affinity with the pressure-sensitive adhesive layer and is wound into a roll. In some cases, the base material layer and the adhesive layer may be more adhesive than necessary, and therefore it is preferable to use a resin mainly composed of polyethylene on the surface of the base material layer. In addition, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composition layer containing a propylene copolymer and high-density polyethylene has been proposed (for example, Patent Document 2), and a styrene block polymer is added for the purpose of improving adhesiveness. It is disclosed that it may be.

However, when an adhesive film having an adhesive layer having such a composition is used as a surface protective film, the peel strength may vary greatly depending on the peel rate, and the peel stability at the time of peel may be poor.

JP 11-21519 A (Claim 1) JP 2002-226814 A (Claim 6, paragraph 0039)

An object of the present invention is to provide a pressure-sensitive adhesive film having an appropriate adhesive strength (peel strength) and a stable peel strength (less depending on the peel rate) even if the peel rate is changed during peeling.

This invention provides the adhesive film which can achieve said objective. That is, the present invention provides an amorphous olefin copolymer (a) having a molecular weight distribution (Mw / Mn) of 3 or less and an intrinsic viscosity (η) in the range of 1.3 to 6.0 dl / g; 20 Crystalline olefin polymer (b) comprising a propylene polymer having a melting point (Tm) of 110 to 156 ° C. in the range of ˜80 parts by mass; hydrogenated product of 3 to 30 parts by mass and the styrene block copolymer The thermoplastic elastomer (c) having a styrenic block of 15 to 25% by mass ; 10 to 50 parts by mass [(a) (b) and (c) in total is 100 parts by mass), An adhesive layer made of a composition having a maximum loss tangent (tan δ) at 10 Hz in a temperature range of −20 ° C. to 5 ° C. and a tan δ of 0.2 to less than 1.0 is laminated on the base material layer. In an adhesive film characterized by To.

According to the present invention, there is an appropriate adhesive strength, excellent peeling stability, maintaining a suitable adhesive property by preventing change over time, no adhesive residue on the adherend surface after use, adhesive performance It is possible to provide an excellent pressure-sensitive adhesive film with little variation.

Amorphous olefin copolymer (a)
The amorphous olefin copolymer (a) according to the present invention is amorphous, and preferably has a heat of crystal fusion in the range of 20 to 250 ° C. in DSC (differential scanning calorimetry) based on JISK7122. It is a copolymer having no peak of 1 J / g or more, more preferably 0.5 J / g or more. The amorphous olefin copolymer (a) according to the present invention is a copolymer of two or more α-olefins. Specifically, these α-olefins have 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, preferably 2 10 to α-olefins are exemplified. The amorphous olefin copolymer (a) according to the present invention includes, in addition to the α-olefin, a polyene compound unit such as butadiene, isoprene, ethylidene norbornene, dicyclopentadiene, a cyclic olefin unit, and a vinyl aromatic as necessary. It may contain at least one unit selected from the group consisting of group compound units.

Specific examples of the amorphous olefin copolymer (a) according to the present invention include, for example, propylene / ethylene copolymer, propylene / ethylene / 1-butene copolymer, propylene / 1-butene copolymer, propylene -Ethylene / cyclic olefin copolymer, propylene / ethylene / butadiene copolymer, propylene / 1-butene / styrene copolymer and the like. Among these copolymers, a propylene / ethylene copolymer or a propylene / ethylene / 1-butene copolymer is most preferable. The molecular weight distribution (Mw / Mn) of the amorphous olefin copolymer (a) according to the present invention is determined by the adhesive strength of the resulting adhesive film, particularly at high temperatures, and the difficulty of the adhesive remaining on the adherend surface. From the viewpoint, it is preferably 3 or less, more preferably 2.8 or less, and still more preferably 2.5 or less. The intrinsic viscosity [η] of the amorphous olefin copolymer (a) according to the present invention is determined by the adhesive strength of the resulting adhesive film, the difficulty of the adhesive remaining on the adherend surface, and the adhesive strength at high temperatures. From the viewpoint, it is preferably in the range of 0.5 to 10 dl / g, more preferably 1.0 to 8.0 dl / g, still more preferably 1.3 to 6.0 dl / g. The amorphous olefin copolymer (a) according to the present invention may be any of a random copolymer and a block copolymer as long as it is amorphous. In the case of a block copolymer, an α-olefin as a main component, for example, propylene, 1-butene or the like is preferably a polymer bonded with an atactic structure. The amorphous olefin copolymer (a) according to the present invention may be a single copolymer or two or more kinds of copolymers.

The amorphous olefin copolymer (a) according to the present invention can be produced using a polymerization catalyst such as a known Ziegler-Natta type catalyst or a single site catalyst (for example, a metallocene catalyst). From the viewpoint of the uniformity of the composition distribution of the resulting amorphous olefin copolymer (a), a preferred catalyst is a general formula VO (OR) nX3-n (wherein R is a Ziegler-Natta type catalyst) Hydrocarbon group, X is halogen, and n is a numerical value satisfying 0 ≦ n ≦ 3) or a single site catalyst such as a metallocene catalyst.

Crystalline olefin polymer (b)
The crystalline olefin polymer (b) according to the present invention is crystalline, preferably 95 to 250 ° C., preferably 100 to 170 ° C., more preferably DSC (differential scanning calorimetry) based on JISK7121. Is a polymer having a peak (melting point; Tm) in the range of 110 to 156 ° C. The crystalline olefin polymer (b) according to the present invention includes homopolymers of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl / 1-pentene and 1-octene, two kinds Copolymers of the above different α-olefins or polymers mainly composed of α-olefins of α-olefins and other polymerizable compounds of vinyl acetate, α, β-unsaturated carboxylic acids or derivatives thereof, and crystalline The polymer.

One specific example of these crystalline olefin polymers (b) is a single polymer of ethylene produced and sold under the names of high pressure method low density polyethylene, linear low density polyethylene (so-called LLDPE) and high density polyethylene. A random copolymer of ethylene and propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl / 1-pentene, 1-octene, 1-decene and the like. And a polymer mainly composed of ethylene having a density of 0.900 to 0.970 g / cm3, preferably 0.905 to 0.940 g / cm3 [ethylene polymer (b-1)]. can do. As one specific example of the crystalline olefin polymer (b), a homopolymer of propylene manufactured and sold under the name of polypropylene, propylene and ethylene, 1-butene, 1-pentene, 1-hexene, 4 -A random or block copolymer with one or more other α-olefins such as methyl 1-pentene, 1-octene, 1-decene, etc., and usually has a melting point (Tm) of 100 to 170 ° C, preferably 110 to 156 A polymer mainly composed of propylene in the range of ° C. [propylene polymer (b-2)] can be exemplified. As one specific example of the crystalline olefin polymer (b), a homopolymer of 1-butene manufactured or sold under the name of polybutene or 1-butene and ethylene, propylene, 1-pentene, 1-hexene , 4-methyl / 1-pentene, 1-octene, 1-decene and other random copolymers with one or more α-olefins, usually having a melting point (Tm) of 95 to 130 ° C., preferably 95 to A polymer mainly composed of 1-butene in the range of 127 ° C. (1-butene polymer) can be exemplified. As one specific example of the crystalline olefin polymer (b), a 4-methyl / 1-pentene homopolymer or 4-methyl-1 produced and sold under the name 4-methyl / 1-pentene A random copolymer of pentene and other one or more α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, etc., usually melting point (Tm) Is a polymer mainly composed of 4-methyl / 1-pentene (4-methyl / 1-pentene polymer) in the range of 200 to 250 ° C., preferably 220 to 240 ° C. Specific examples of the crystalline olefin polymer (b) include ethylene and acrylic acid, methacrylic acid, vinyl acetate, vinyl acetate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, and ethyl methacrylate. And other polymerizable compounds, preferably a copolymer with a vinyl compound (ethylene-vinyl compound copolymer). The crystalline olefin polymer (b) according to the present invention may be a single polymer or two or more polymers. Among these crystalline olefin polymers (b), a propylene polymer having a melting point (Tm) of 100 to 160 ° C, particularly 110 to 156 ° C is preferable.

Thermoplastic elastomer (c)
Scan styrene-based elastomer is preferably a thermoplastic elastomer (c) according to the present invention.

As the styrene elastomer, there is a styrene block copolymer, which is a copolymer of a vinyl aromatic compound and a conjugated diene compound, and the vinyl aromatic compound (X) and the conjugated diene compound (Y) are X There are block copolymers polymerized in a state represented by-(Y-X) m (m is an integer of 1 or more) or (XY) n (n is an integer of 1 or more). Among these, the XY type or the XY type is preferable.

Specific examples of the vinyl aromatic compound (X) include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylstyrene, 1,1-diphenylstyrene, and the like. Of these, styrene and α-methyl styrene are preferable.

Specific examples of the conjugated diene compound (Y) include 1,3-butadiene, isoprene, 2,3-dimethyl 1,3-butadiene, 1,3-pentadiene, 2-methyl 1,3-pentadiene, and isoprene.

Specific examples of these styrenic block copolymers include styrene-butadiene-styrene block copolymers and styrene-isoprene-styrene block copolymers, and these are preferably partially or wholly hydrogenated polymers. . Specifically, styrene-butadiene-styrene block copolymer resin (SBS), styrene-ethylene-butylene-styrene block copolymer resin (SEBS) obtained by hydrogenating the butadiene portion, styrene-isoprene-styrene block copolymer. Polymer resin (SIS), styrene-ethylene / propylene-styrene block copolymer resin (SEPS) obtained by hydrogenation of its isoprene part, butadiene part of random copolymer block of styrene polymer block and styrene and butadiene Examples thereof include a block copolymer resin obtained by hydrogenation, a block copolymer resin obtained by hydrogenation of the isoprene portion of a random copolymer block of a styrene polymer block and styrene and isoprene, and the like.

As a commercial product of the hydrogenated product (SEBS) of an XY-X type block copolymer of styrene and 1,3-butadiene, for example, trade names manufactured by Shell Chemical Co., Ltd .: Kraton G, trade names manufactured by Asahi Kasei Corporation : Tuftec can be mentioned. Further, a copolymer having high randomness among copolymers of styrene and 1,3-butadiene is generally abbreviated as HSBR, and as a commercial product, for example, trade name: Dynalon manufactured by JSR Corporation can be exemplified. . Moreover, as a commercial item of the hydrogenated product (SEPS) of the XYX type block copolymer of styrene and isoprene, the Kuraray Co., Ltd. brand name: Hybler, Septon, etc. can be mentioned, for example.

The content of the styrene-based polymer block and a conjugated diene polymer block in the styrene-based block polymer is not particularly limited, Conjugate diene block 75 to 85% by weight and a styrene polymer block 15 -25% by mass , among which conjugated diene block 80-85% by mass and styrene block 15-20% by mass are preferable.

Moreover, as a copolymer containing the block which consists of a polymer of a vinyl aromatic compound, and the block of a crystalline olefin, there exists a block copolymer represented by St-B-C, and a styrene * ethylene-butylene * ethylene block A copolymer (SEBC) is illustrated. Used butylene-ethylene block copolymer (SEBC) - as a thermoplastic elastomer, a copolymer comprising a block of a polymer of copolymer and vinyl-aromatic compound containing a block of crystalline olefin, inter alia styrene-ethylene As a result, it is possible to obtain a pressure-sensitive adhesive film that not only has excellent peel stability at high speed but also has an excellent performance that the change in peel strength with time after starting actual use of the pressure-sensitive adhesive film is extremely small.

The above thermoplastic elastomer has a maximum temperature of loss tangent (tan δ) at 10 Hz in dynamic viscoelasticity measurement in the range of −60 ° C. to −30 in order to make appropriate tackiness and peelability at a low temperature within a suitable range. It is preferable that it is degree C, and also -60 to -40 degree C is a particularly preferable range.

Adhesive layer The adhesive layer of the adhesive film of the present invention is a composition comprising the amorphous olefin copolymer (a), the crystalline olefin (b), and the thermoplastic elastomer (c). And the maximum value of the loss tangent (tan δ) at 10 Hz is at a temperature of −20 ° C. to 5 ° C., and the tan δ is 0.2 or more and less than 1.0.

Here, the loss tangent (tan δ) is a ratio of the loss elastic modulus to the storage elastic modulus [G ′], and means a phase from when a stress is applied to the sample until distortion occurs.

As a guideline for preparing a composition suitable for the adhesive layer, each component contained in the composition is 20 to 80 parts by mass of an amorphous olefin copolymer (a), 3 to 30 parts by mass of a crystalline olefin (b), heat It is desirable that the plastic elastomer (c) be in the range of 10 to 50 parts by mass (the total of (a), (b) and (c) is 100 parts by mass).

By adjusting the monomer composition, molecular weight, etc. of each component polymer of such a composition, the maximum value of the loss tangent (tan δ) at 10 Hz is at a temperature of −20 ° C. to 5 ° C., and tan δ is 0.2 or more. A composition that is less than 1.0, preferably 0.3 or more and 1.0 or less can be prepared.

Furthermore, the initial adhesive strength (by the method shown in the Examples) of such a composition is desirably in the range of 200 to 700 g / 50 mm. If it is less than 200 g / 50 mm, the adhesive strength tends to be insufficient, and if it exceeds 700 g / 50 mm, it tends to be difficult to control the adhesive performance.

In addition to the amorphous olefin copolymer (a), the crystalline olefin (b) and the thermoplastic elastomer, other components can be blended in the adhesive layer as necessary. In order to control the adhesive performance and reduce the variation, it is desirable to keep other polymer components in a small amount even when blended.

In addition, anti-aging agents, antioxidants, ozone degradation inhibitors, ultraviolet absorbers, stabilizers such as light stabilizers, antistatic agents, slip agents, colorants, dispersants, anti-blocking agents, lubricants, anti-static agents. An additive such as a clouding agent is blended as necessary.

In order to prepare the composition used for the adhesive layer, for example, each component is kneaded by a usual kneading apparatus such as a rubber mill, a Brabender mixer, a Banbury mixer, a pressure kneader, a ruder and a twin screw extruder. Can be illustrated.

The kneading apparatus may be either a closed type or an open type, but a closed type apparatus that can be replaced with an inert gas is preferable. The kneading temperature is usually 120 to 250 ° C, preferably 140 to 240 ° C. The kneading time depends on the type and amount of the components used and the type of the kneading apparatus, and is usually about 3 to 10 minutes when a kneading apparatus such as a pressure kneader or a Banbury mixer is used. . In the kneading step, a method of kneading each component in a lump may be adopted, or a multi-stage division kneading method in which a part of each component is kneaded and then the remainder is added to continue kneading. It may be adopted.

Base material layer Various conventionally known materials can be used for the base material layer according to the pressure-sensitive adhesive film of the present invention. The thermoplastic resin for the base layer is not particularly limited, and polypropylene-based resin such as crystalline polypropylene, a homopolymer of propylene, and a random or block copolymer of propylene and a small amount of α-olefin; low density polyethylene Polyethylene resins such as medium density polyethylene, high density polyethylene and linear low density polyethylene, poly-4-methyl-pentene-1, ethylene-α-olefin copolymers. Propylene-α-olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-n-butyl acrylate copolymer with α-olefin unit as main unit Coalescence and combinations thereof are exemplified.

Among these, from the viewpoint of obtaining an adhesive film excellent in adhesiveness and peelability, from the viewpoint of obtaining an adhesive film in which the base material layer and the adhesive layer are not easily peeled, and from the viewpoint of recyclability of the adhesive film, the present invention. Polyethylene resins and polypropylene resins having good compatibility with the amorphous olefin copolymer (a) used in the above are preferred.

Furthermore, when a resin mainly composed of polypropylene is used for the pressure-sensitive adhesive layer, the use of a polypropylene-based resin for the base material layer has a high affinity with the pressure-sensitive adhesive layer. Since the adhesive layer may exhibit more adhesiveness than necessary, it is preferable to use a resin mainly composed of polyethylene for the base material layer.

Furthermore, when a resin mainly composed of polypropylene is used for the pressure-sensitive adhesive layer, using a polypropylene resin for the base material layer has a high affinity with the pressure-sensitive adhesive layer. The layer may be more tacky than necessary. Therefore, it is preferable to use a resin mainly composed of polyethylene on the surface opposite to the surface on which the adhesive layer of the base material layer is laminated. Examples of polyethylene include low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene. Particularly, a surface mainly composed of low-density polyethylene is preferable. The base material layer may be a single layer or a multilayer composed of at least two layers. The surface of the base material layer may be treated by a known surface treatment method such as corona discharge treatment, plasma treatment, flame treatment, electron beam irradiation treatment, and ultraviolet irradiation treatment. The base material layer may be a colorless and transparent layer, or a colored or printed layer. As an aspect in which the base material layer is a multilayer, the base material layer is composed mainly of a relatively rigid intermediate layer such as a film of polypropylene, polyethylene terephthalate, hard acrylic resin, kraft paper, synthetic paper, and polyethylene on the surface thereof. There is a base material layer as a surface layer. The thickness of the intermediate layer / surface layer is usually about 3 to 100 μm / 3 to 50 μm, respectively. By making the surface of the equipment layer polyethylene, even when the adhesive of the adhesive film is in contact with the surface layer and wound up in a roll, the rewinding property when the adhesive film is rewound again and used ( The peelability between the surface of the pressure-sensitive adhesive layer and the base material layer is smooth, and excellent handleability is obtained.

Pressure-sensitive adhesive film The pressure-sensitive adhesive film of the present invention may be a pressure-sensitive adhesive film having the pressure-sensitive adhesive layer on one side of the base material layer, or the pressure-sensitive adhesive layer on both sides of the base material layer. It may be an adhesive film having

As a method for producing the pressure-sensitive adhesive film of the present invention, using a device such as an inflation film production device or a T-die film production device, a method of co-extrusion of the base material layer and the pressure-sensitive adhesive layer or a method of extrusion coating (“ Also referred to as an “extrusion laminating method”. In particular, the method of producing a laminated film having a predetermined thickness by melting and heating the materials constituting the base material layer and the adhesive layer, respectively, and producing the film of the present invention with high efficiency and low cost. It is preferable in that it can be performed.

The base material layer may be previously stretched in a uniaxial direction or a biaxial direction as necessary. As a preferred method for uniaxial stretching, a commonly used roll stretching method can be exemplified. Examples of the biaxial stretching method include a sequential stretching method in which biaxial stretching is performed after uniaxial stretching, and a simultaneous biaxial stretching method such as a tubular stretching method.

Although the thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film of the present invention is not particularly limited, it is usually about 1 to 200 μm, and when the film of the present invention is produced by coextrusion, the layer structure of the film is easily controlled, From workability of sticking or peeling, it is desirable to set it as 3-50 micrometers. Moreover, although the whole thickness of an adhesive film is not specifically limited, Usually, about 10-300 micrometers, Preferably it is about 30-200 micrometers. Each thickness of a base material layer and an adhesive layer can be determined according to the kind of to-be-adhered body, and the physical property requested | required of an adhesive film.

The present invention will be described more specifically with reference to the following examples, which are illustrative only and are not intended to limit the present invention.

Example 1
The raw material resin for the adhesive layer was prepared as follows. That is, the amorphous olefin copolymer (amorphous PO) shown in Table 1 and propylene random copolymer (r-PP) at 132 ° C. (mass ratio of amorphous PO / r-PP is 85/15) 60 parts by mass of Tough Selenium T3714 (MI at 230 ° C., 2.16 kg load, manufactured by Sumitomo Chemical Co., Ltd.) and SEPS (Kuraray Co., Ltd., Septon S2004 (styrene / ethylene Propylene ratio = 18/82, MFR (230 ° C., load 2.16 Kg) 5.0 g / 10 min)) 40 mass parts of the raw material resin for the adhesive layer was prepared. The maximum tan δ temperature and tan δ value of the obtained raw material resin for the adhesive layer were measured or evaluated according to the following methods. The results are shown in Table 2. On the other hand, the raw material resin of the base material layer was prepared from 70 parts by mass of high density polyethylene (density: 0.953 g / cm 3) and 30 parts by mass of low density polyethylene (density: 0.917 g / cm 3).

Using these two layers of raw material resin, a co-extruded T-die film of a suitable laminated film (thickness: 50 μm) consisting of an adhesive layer (thickness: 8 μm) and a base material layer (thickness: 42 μm) Molded by a molding method. The molding conditions are as follows. Molding conditions Melting temperature (extruder setting temperature): substrate layer 220 ° C., adhesive layer 210 ° C. Coextrusion temperature (die setting temperature): 210 ° C. Regarding the initial adhesive strength and peel stability of the obtained laminated film, the following methods Measurement or evaluation was performed according to The results are shown in Table 2.

Examples 2 and 3, Comparative Examples 1 and 2, Reference Example 1
A laminated film is produced in the same manner as in Example 1 except that the adhesive layer has the composition shown in Table 2.
Similar to Example 1, the initial adhesive strength and peel stability were measured or evaluated. The results are shown in Table 2. Tuftec H1062 is SEBS (styrene / ethylene / butylene ratio = 18/82, MFR (230 ° C., load 2.16 Kg) 4.5 g / 10 min) manufactured by Asahi Kasei Co., Ltd., Dynalon 8601P is a JSR stock SEBS (styrene / ethylene / butylene ratio = 15/85, MFR (230 ° C., load 2.16 kg) 3.5 g / 10 min) manufactured by company, and Septon S2063 is SEPS (styrene / ethylene manufactured by Kuraray Co., Ltd.) Propylene ratio = 13/87, MFR (230 ° C., load 2.16 Kg) 7.0 g / 10 min), Tuftec H1221 is SEBS (styrene / ethylene / butylene ratio = 12/88, manufactured by Asahi Kasei Corporation) MFR (230 ° C., load 2.16 Kg) 4.5 g / 10 min).

Example 4
It was carried out in the same manner as in Example 1 except that the raw material resin for the adhesive layer had the composition shown in Table 1 and the base material layer was a base material layer described below. Dynalon 4600P is SEBC (styrene content: 20% by mass, MFR (230 ° C., load 2.16 Kg) 5.6 g / 10 min) manufactured by JSR Corporation.
Base material layer:
Intermediate layer: Propylene / ethylene random copolymer (Random PP: Mitsui Chemicals, Inc., trade name: Mitsui Polypro F327, density: 0.91 g / cm3, melting point: 138 ° C.) 96 parts by mass and high density polyethylene (density) : 0.953 g / cm3) 4 parts by mass.
Surface layer: composed of 100 parts by mass of low density polyethylene (density: 0.917 g / cm 3).
An adhesive film (thickness: 50 μm) consisting of an adhesive layer (thickness: 8 μm), a base material layer (intermediate layer (thickness: 37 μm)) and a surface layer (thickness: 5 μm) is co-extruded T-die film molding method The molding conditions were: melting temperature (set temperature of the extruder): substrate layer (intermediate layer 220 ° C., surface layer 220 ° C.), adhesive layer 210 ° C., co-extrusion temperature (die Setting temperature): 210 ° C. The adhesive strength of the adhesive film of Example 4 before and after aging was initial: 390 (g / 50 mm), after aging: 400 (g / 50 mm), and the variation in adhesive strength was very small. The initial adhesive strength and peel stability of the obtained adhesive film were measured or evaluated, and the results are shown in Table 2.
(Evaluation item)
<Measurement of maximum tan δ temperature and tan δ value>
The temperature at which the tan δ value of the dynamic viscoelasticity measurement in the measurement temperature range of −100 ° C. to 100 ° C. of the pressure-sensitive adhesive resin used for the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film, and the value of tan δ at that time are RSA manufactured by Rheometrics Using -III, a temperature change of −100 ° C. to 100 ° C. was applied and measured while applying a tensile strain at a heating rate of 3 ° C./min and a frequency of 10 Hz. As a measurement sample, an adhesive sheet having a thickness of about 1 mm was prepared and measured.

<Measurement of adhesive strength>
The adhesive film was attached to the surface of the acrylic plate using a 2 kg pressure roller at 23 ° C., and left at 23 ° C. for 30 minutes, then in a 23 ° C. atmosphere, peeling width 50 mm, peeling angle 180 °, peeling speed 300 mm / min and peeling. The force required to peel the adhesive film from the acrylic plate under the condition of a speed of 1000 mm / min was measured, and the average value was taken as the adhesive strength at 23 ° C. (g / 50 mm).

<Evaluation of peeling stability>
The adhesive film was attached to the surface of the acrylic plate using a 2 kg pressure roller at 23 ° C., and left at 23 ° C. for 30 minutes, then in a 23 ° C. atmosphere, peeling width 50 mm, peeling angle 180 °, peeling speed 300 mm / min and peeling. The pressure-sensitive adhesive film was peeled from the acrylic plate under the condition of a speed of 1000 mm / min.

<Adhesive strength after time>
The adhesive film was attached to the surface of the acrylic plate using a 2 kg pressure roller at 23 ° C., held for 1 week at 50 ° C. and 0.2 kg / cm 2 pressure, and then the attached plate was left in a 23 ° C. atmosphere for about 2 hours. After cooling, the pressure-sensitive adhesive film was peeled from the acrylic plate under the conditions of a peeling width of 50 mm, a peeling angle of 180 °, and a peeling speed of 300 mm / min, and the force required at that time was defined as the adhesive strength after aging (g / 50 mm). . The closer this value is to the initial adhesive strength, the better.

Table 1

Table 2 is shown below. Note 1 to 6 in the table are as follows, and the styrene elastomers of Note 1 to Note 4 have a glass transition temperature (Tg) in the range of −40 to −50 ° C., Note 5 The styrene elastomer has a glass transition temperature (Tg) in the range of −35 to −30 ° C.
Note 1: Septon S2004 Kuraray Co., Ltd. (styrene / ethylene / propylene ratio = 18/82, MFR (230 ° C., load 2.16 Kg) 5.0 g / 10 min)
* Note 2: Tuftec H1062 Asahi Kasei Corporation (styrene / ethylene / butylene ratio = 18/82, MFR (230 ° C., load 2.16 kg) 4.5 g / 10 min)
* 3: Made by Dynalon 8601PJSR (styrene / ethylene / butylene ratio = 15/85, MFR (230 ° C., load 2.16 kg) 3.5 g / 10 min)
* 4: Septon S2063, Kuraray Co., Ltd. (styrene / ethylene / propylene ratio = 13/87, MFR (230 ° C., load 2.16 Kg) 7.0 g / 10 min)
・ Note 5: Tuftec H1221 Asahi Kasei Co., Ltd. (styrene / ethylene / butylene ratio = 12/88, MFR (230 ° C., load 2.16 kg) 4.5 g / 10 min)
* 6: Made by Dynalon 4600PJSR (styrene content: 20% by mass), MFR (230 ° C., load 2.16 kg) 5.6 g / 10 min

The adhesive film of the present invention is used for electronics applications such as semiconductor wafer backgrind tape, dicing tape, printed circuit board protection tape, window glass protection film, decorative marking film, medical and sanitary use. Used in a wide range of applications such as drug bases.

Claims (2)

Amorphous olefin copolymer (a) having a molecular weight distribution (Mw / Mn) of 3 or less and an intrinsic viscosity (η) in the range of 1.3 to 6.0 dl / g; 20 to 80 parts by mass;
A crystalline olefin polymer (b) comprising a propylene polymer having a melting point (Tm) in the range of 110 to 156 ° C .; 3-30 parts by mass and a hydrogenated product of a styrene block copolymer , Thermoplastic elastomer (c) whose system block is 15 to 25% by mass ; 10 to 50 parts by mass [the total of (a), (b) and (c) is 100 parts by mass]
Consists of
An adhesive layer made of a composition having a maximum loss tangent (tan δ) at 10 Hz in a temperature range of −20 ° C. to 5 ° C. and a tan δ of 0.2 to less than 1.0 is laminated on the base material layer. An adhesive film characterized by being made. The pressure-sensitive adhesive film according to claim 1, wherein the amorphous olefin copolymer (a) is a propylene / ethylene copolymer or a propylene / ethylene / 1-butene copolymer .