JP2010229222A - Pressure sensitive adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensitive adhesive film which especially shows less blocking even after storing the adhesive film in a rolled state, excels in processing aptitude, shows no change in its adhesive strength with age after being attached to an adherend, causes no stain of the adherend upon film release, and has less fish eyes. <P>SOLUTION: This pressure sensitive adhesive film is a polypropylene pressure sensitive adhesive film which has a pressure sensitive adhesive layer formed on one side of the substrate layer and a release layer laminated on the other side of the substrate, wherein the average surface roughness SRa at a surface of the release layer is &le;0.200 &mu;m, and the average surface roughness SRa at a surface of the pressure sensitive adhesive layer is &le;0.030 &mu;m. Owing to the fact that a &le;4C polyolefin elastomer is used as a main component in the pressure sensitive adhesive layer and a block copolymer is used in the release layer, the pressure sensitive adhesive film has: a film haze of &le;25%; excellent blocking resistance in a rolled state; a tensile modulus of the film of &ge;20 MPa in an environment of 100&deg;C; and excellent handleability upon elevated temperature treatment. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an adhesive film. The pressure-sensitive adhesive film of the present invention protects the surface of an article from undesirable effects such as dust adhesion and scratching by sticking it on the surface of an article such as a synthetic resin plate, a decorative plywood, a metal plate, and a coated steel plate. It can be particularly preferably used as a surface protective film for the purpose and as a surface protective film when the printed circuit board is immersed in solder. The term “adhesive film” in the present invention also means an adhesive sheet or an adhesive tape.

  Conventionally, adhesive films aimed at protecting the surface of coatings have been used during processing, storage, and transportation of building materials, electrical, electronic products, automobiles, etc. Such adhesive films have good adhesive properties. In addition, after use, each surface must be able to be easily peeled off without being contaminated with an adhesive. In recent years, adhesive films based on polyolefin resins have been used instead of adhesive films based on plasticized vinyl chloride resins. However, these polyolefin resin-based adhesive films are made of polyolefin-based substrates coated with an adhesive, low crystalline or amorphous adhesive layers such as EVA and low-density polyethylene. In addition, a copolymer elastomer such as propylene-ethylene, propylene-butene or the like formed integrally with a base material layer by coextrusion is used. However, these adhesive films are easily affected by the environment in which the joined body is placed, especially in a high temperature environment, causing extreme changes over time, and thus the adhesive force is increased and peeling from the adherend is difficult. And there are problems such that the adhesive remains on the adherend.

For this problem, an amorphous olefin polymer and a specific ethylene-based polymer are used as a pressure-sensitive adhesive that maintains suitable tackiness under extreme low temperature and high temperature conditions regardless of the operating temperature range. A composition made of a polymer has been proposed (see, for example, Patent Documents 1, 2, and 3).
However, the above adhesive film also has a problem of blocking due to storage.

Moreover, the film which provided the surface layer which has specific surface roughness on the opposite surface of the adhesion layer, and improved the blocking resistance is disclosed. (For example, see Reference 4)
However, this film was not sufficient in terms of performance.
Moreover, the problem of the external appearance by a fish eye and the blocking resistance of an adhesion layer and a base material layer are inadequate, and it is anticipated that blocking will arise depending on the storage state in a roll state.

  Moreover, although it has disclosed about the adhesive film which added the tackifier to the adhesion layer (for example, refer to the reference document 5), problems, such as to-be-adhered object stain | pollution | contamination in a high temperature environment, and adhesive force progress, are recognized.

JP 2006-63123 A JP 2006-299060 A JP 2006-257191 A JP 2008-68564 A JP 2006-335989 A

  The problem to be solved by the present invention is that there is little blocking between the pressure-sensitive adhesive films, in particular, there is little blocking even after the pressure-sensitive adhesive film is stored in a roll state, it is excellent in workability, and after being bonded to the adherend, An object of the present invention is to provide a pressure-sensitive adhesive film that does not change in force, has no stain on the adherend when the film is peeled off, has excellent handling properties at room temperature / high temperature processing, and has few fish eyes.

That is, the present invention has less blocking between the adhesive films, particularly less blocking even after the adhesive film is stored in a roll state, excellent handling at the time of processing, and adhesive strength over time after being bonded to an adherend. The object of the present invention is to provide a pressure-sensitive adhesive film that does not change, has no stain on the adherend when the film is peeled off, has excellent handling properties at room temperature / high temperature processing, and has few fish eyes.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have laminated an adhesive layer on one side of the base material layer and a release layer on the opposite side, and an average surface roughness SRa of the release layer surface. Is a polypropylene adhesive film having an adhesive layer surface average surface roughness SRa of 0.030 μm or less, wherein the adhesive layer is mainly composed of a C4 or less polyolefin elastomer, and the release layer By using a block copolymer, the haze value of the film is 25% or less, excellent in blocking resistance in a roll state, transparent and low-temperature feeling during high-temperature treatment, specifically even in an environment of 100 ° C. It has been found that an adhesive film having an elastic modulus of 90 MPa or more and excellent in handling properties and impact resistance can be obtained, and has reached the present invention.

  In this case, it is preferable that the adhesive layer is a mixture mainly composed of a propylene-based polymer.

  Furthermore, in this case, it is preferable that the average surface roughness SRa of the release layer is 0.150 μm or less.

  Furthermore, in this case, it is preferable that the average surface roughness SRa of the adhesive layer is 0.020 μm or less.

  Furthermore, in this case, it is preferable that the base material layer, the adhesive layer, and the release layer are melt-extruded and laminated from a plurality of extruders by a coextrusion method.

  Furthermore, in this case, a film roll made of the film and having a width of 450 mm or more and a length of 300 m or more is preferable.

  The pressure-sensitive adhesive film according to the present invention has no blocking during roll storage, is transparent, has little FE, does not vary in adhesive strength with time, and has little contamination of the adherend. In addition, it is excellent in handling at the time of sticking and peeling from the adherend, and because these properties are manifested by film formation by coextrusion with a multi-layer structure, it is possible to use adhesive coating and satin roll There is no need for mold release processing, and it is excellent in productivity.

  Hereinafter, embodiments of the pressure-sensitive adhesive film of the present invention will be described.

(Base material layer)
The pressure-sensitive adhesive film of the present invention requires a base material layer made of a polypropylene resin, and examples of the polypropylene resin used here include crystalline polypropylene, propylene and a small amount of an α-olefin copolymer. , N-heptane-insoluble isotactic propylene homopolymer used in ordinary extrusion molding as a crystalline polypropylene resin, or a copolymer of polypropylene and other α-olefins containing 60% by weight or more of propylene These propylene homopolymers or copolymers of propylene and other α-olefins can be used alone or in admixture.
Here, n-heptane insolubility indicates the crystallinity of polypropylene as well as safety. In the present invention, n-heptane insolubility (25 ° C., 60 ° C.) according to Ministry of Health and Welfare Notification No. 20 in February 1982. It is a preferred embodiment to use one that is compatible with an elution amount of 150 pPm or less (if the operating temperature exceeds 100 ° C., 30 PPm or less) at the time of partial extraction.

  Moreover, a melt flow rate (MFR) is 0.1-100 g / 10min, Preferably it is 0.5-20 g / 10min, More preferably, the thing of the range of 1.0-10 g / 10min can be illustrated. A range of 3.0 to 8.0 g / 10 min is particularly preferable. Two or more types of copolymers of propylene and other α-olefins may be mixed and used.

(Adhesive layer)
In addition, as a resin used for the adhesive layer, which is a requirement of the present invention, an olefin polymer, particularly a propylene-ethylene copolymer, is used for the purpose of laminating an adhesive layer on a layer made of polypropylene resin. It is desirable from the standpoints of improving the adhesion, preventing the adhesive layer from remaining on the adherend after peeling, and stabilizing the adhesive force.

Furthermore, in order to achieve a contact area ratio with the adherend that is a requirement of the present invention, the adhesive layer preferably contains a polyolefin-based elastomer.
As a method for containing the polyolefin-based elastomer, it is preferable to use the resin mentioned in the following (1) or (2).

(1) A polymerization type thermoplastic elastomer in which an olefin rubber is finely dispersed in a polypropylene resin matrix.
An example of a polymerization type thermoplastic elastomer in which an olefin rubber is finely dispersed in a polypropylene resin matrix is "Zeras MC707" manufactured by Mitsubishi Chemical Corporation.

(2) A mixture of an amorphous polypropylene resin consisting only of a propylene-based resin and a resin exemplified below with respect to the total weight of the layer of 15% by weight or more and 50% by weight or less, such as an ethylene-propylene copolymer. It is done. The melt flow rate is preferably in the range of 1 to 10 g / 10 minutes.

The average surface roughness SRa of the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film of the present invention needs to be 0.010 μm or more and 0.030 μm or less. Preferably, it is 0.025 μm or less, more preferably 0.020 μm or less, and particularly preferably 0.015 μm or less.
Here, when the average surface roughness SRa of the surface of the pressure-sensitive adhesive layer exceeds 0.030 μm, the contact area is reduced at the time of bonding to the adherend, which causes a decrease in the adhesive strength, which is not preferable. One of the factors that determine the adhesive strength is the force that attracts materials, that is, the van der Waals force, on each surface of the laminated film that is in contact. Yes. Here, the fact that the contact area is small means that the attractive force between the bonded film surface and the adherend surface is reduced, which is not preferable because the adhesive force is lowered.
Moreover, it is necessary to make the surface of the adhesive layer as flat as possible, and it is preferable not to add an additive that forms surface irregularities.
On the other hand, it can be said that it is practically difficult to make the average surface roughness SRa of the surface of the adhesive layer less than 0.010 μm even in a stretched film without additives.

  As a method for improving the smoothness of the adhesive layer surface, in addition to using no additives as described above, the compatibility of the resin is improved, the roll surface during film production, especially a cooling roll that cools and solidifies the molten resin Examples include surface smoothing.

The thickness of the pressure-sensitive adhesive layer of the present invention is preferably 1 μm or more and less than 30 μm.
When the thickness of the pressure-sensitive adhesive film is less than 1 μm, there are problems such as adhesive stability and insufficient strength, and when it is 30 μm or more, there are problems such as a feeling of film stiffness and blocking in a roll state.
At this time, when increasing the adhesive strength, it is preferable to increase the thickness in consideration of the viscosity. When the thickness of the adhesive layer is large, it is easy to follow the shape of the adherend surface, the contact area is easily increased, and this is particularly effective when a hard resin is used for the adhesive layer.
In terms of blocking, the thickness of the adhesive layer is preferably 2 μm or more and 20 μm or less, more preferably 2 μm or more and 15 μm or less, and particularly preferably 2 μm or more and 10 μm or less.

(Release layer)
The pressure-sensitive adhesive film of the present invention forms a release layer on the opposite surface of the pressure-sensitive adhesive layer, so that even if the pressure-sensitive adhesive films are stacked, there is little blocking between the pressure-sensitive adhesive films, especially after storing the pressure-sensitive adhesive film in a roll state. Has less blocking and excellent processability.
In this case, the average surface roughness SRa is preferably 0.050 μm or more.
However, simply by providing a release layer, the surface irregularities of the release layer are transferred to the surface of the adhesive layer, and the adhesive force and the above-mentioned adhesion area are reduced, or immediately after being pasted to the adherend and after lapse of time. Since the adhesive force is changed, the average surface roughness SRa is preferably 0.200 μm or less. By doing so, blocking resistance and the protection performance of a to-be-adhered body can be improved, and it becomes possible to suppress the deterioration of transparency.
At this time, the surface unevenness of the release layer is preferably a surface having an average surface roughness SRa of 0.150 μm or less, more preferably 0.060 μm or more and 0.130 μm or less, 0.080 μm or more, Most preferably, it is 0.130 μm or less.

  In order to form the surface irregularities as described above, for example, a layer made of a silicone resin or a fluororesin, a method of blending a polypropylene resin with a polyethylene resin or an EMMA resin, a method of mixing particles such as silica or PMMA, A layer having surface irregularities can be formed by mixing a copolymer of propylene and another α-olefin, or a mixture of these copolymer and propylene resin.

Among these methods for forming surface irregularities, silicone, EMAA, and the like have problems such as insufficient interlayer strength due to poor compatibility with olefinic resins and abnormal appearance. In addition, the method of dispersing particles in a propylene-based resin has operational problems such as performance degradation and contamination due to dropping off of particles during handling, and pressurization of a filter in an extruder during melt extrusion. On the other hand, the method of using a copolymer of another layer propylene, another α-olefin and a copolymer by coextrusion does not have the above-mentioned problem, and can provide a film having good quality and operation.
In this case, it is preferable to use a block copolymer. By using the block copolymer, the propylene matrix has a sea-island structure with the copolymer domain, and fine irregularities are formed on the surface.
Examples of the resin used for the release layer include propylene-ethylene block copolymers such as “PC480A” and “PC523A” manufactured by Sun Allomer Co., Ltd.
“PC523A” manufactured by Sun Allomer Co., Ltd. is advantageous in terms of increasing the average surface roughness, but when used alone, the surface roughness becomes too large and the transparency is greatly reduced.

(Base material layer)
The thickness of the base material layer of the present invention is preferably 5 μm or more and 100 μm or less, and more preferably 15 μm or more and 50 μm or less.
In consideration of workability such as bonding to an adherend and peeling, the adhesive film needs a certain degree of low back. When the thickness of the base material layer is less than 5 μm, there is a problem that the feeling of lower back is weakened, wrinkles, and handleability deteriorates. If it is 100 μm or more, there is a problem in terms of cost.
In order to obtain good handling properties at low cost, the elastic modulus of the entire pressure-sensitive adhesive film at room temperature is preferably 300 MPa or more. The rate is preferably 20 MPa or more.
In order to satisfy these physical properties, it is preferable to use homopolypropylene for the base material layer. By using homopolypropylene, it is possible to improve the heat resistance and to provide a feeling of low back under high temperature conditions.

  The homopolypropylene used for the base material layer can obtain sufficient characteristics by using a commercially available product. The physical properties are those having a melting point of 150 to 165 ° C., a density of 0.88 to 0.92, and an elastic modulus of 1000 to 1800 MPa. Specific examples include FLX80E4 and WF836DG3 manufactured by Sumitomo Chemical Co., Ltd.

(Adhesive film)
The haze value of the pressure-sensitive adhesive film of the present invention is preferably in the range of 1 to 40, particularly when used for an optical adherend. More preferably, it is 1 to 30%, and particularly preferably 1 to 25%.

The pressure-sensitive adhesive film of the present invention is preferably in the form of a roll in terms of handling.
The upper limit of the width and winding length of the film roll is not particularly limited, but from the viewpoint of ease of handling, generally, the width is preferably 3 m or less, and the winding length is preferably 6000 m or less when the film thickness is 45 μm. Moreover, as a winding core, a plastic core and metal cores, such as 3 inches, 6 inches, and 8 inches, can usually be used.
Moreover, it is preferable that it is the film roll wound up by the dimension of length 300m or more and width 450mm or more from the suitability of a process.

  The pressure-sensitive adhesive film of the present invention preferably has a thickness variation rate in the transverse direction, which is a direction orthogonal to the winding direction during film production, in the range of 2.0% or more and 10.0% or less. Is 8.0% or less, more preferably 6.0% or less. When the thickness variation rate exceeds 10.0%, when pressure-sensitive adhesive film is stuck to the adherend, pressure unevenness occurs depending on the location, and the adhesive force is reduced or wound in a roll state. In this case, local blocking and wrinkles may occur, which is not preferable. On the other hand, it can be said that it is practically difficult to suppress the thickness variation rate to less than 2.0%.

The film of the present invention has an adhesive strength measured according to a JIS-Z-0237 adhesive tape / adhesive sheet test method. It is preferable that the difference between the initial adhesive strength at 23 ° C. and the adhesive strength after aging after bonding to the adherend is 10 cN / 25 mm or less.

  The pressure-sensitive adhesive strength of the pressure-sensitive adhesive film of the present application is preferably in the range of 3 to 50 cN / 25 cm at 23 ° C. from the viewpoint of protective performance and peelability of the adherend. The adhesive strength is possible by appropriately setting the adhesive strength by controlling the amount, composition, etc. of the amorphous component of the resin of the adhesive layer.

The adhesive film of this invention can contain a well-known additive as needed in the range which does not impair the target characteristic. For example, a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, an impact resistance improvement agent and the like may be contained.
However, the low molecular weight substance on the surface of the adhesive layer is preferably less than 1 mg / m ² .
Here, the measurement of the low molecular weight substance on the surface of the adhesive layer was carried out by the following procedure. After the surface of the adhesive layer is washed with an organic solvent that does not erode the resin constituting the adhesive layer such as ethanol, the organic solvent is removed from the cleaning solution with an evaporator, and the residue obtained by weighing the residue is washed. It was obtained by dividing by the surface area of the layer surface. Here, if the residue is present in an amount of 1 mg / m ² or more, there will be foreign matter between the surface of the adhesive layer and the adherend surface, which will reduce the contact area and reduce the van der Waals force. Is not preferable. In the case of adding an additive, it is necessary to select an additive such as a polymer type or to examine an addition method so that there is no transfer or transfer to the adhesive layer.

  The adhesive film of the present invention is particularly a synthetic resin plate (for example, for optical members and building materials), a stainless plate (for example, for building materials), an aluminum plate, a decorative plywood, a steel plate, a glass plate, a household appliance, and a precision machine. In order to protect the surface of the automobile body at the time of manufacture, the article is stacked, stored, transported, prevented from being damaged when transported in the manufacturing process, and the article is subjected to secondary processing ( For example, it can be suitably used in order to prevent damage from bending during bending or pressing.

  The following examples further illustrate the invention. However, the present invention is not limited to the following examples without departing from the gist thereof. In addition, the evaluation method of the physical property in a following example and a comparative example is as follows.

(1) Tensile modulus The tensile modulus was measured under the following conditions based on the JIS K 7162 test method.
Specimen: 1A type, gripping distance: 115mm
Distance between marked lines: 50 mm
Speed: 1mm / min
Measurement temperature: 30 ° C, 100 ° C

(2) Measurement of average surface roughness Using a contact type three-dimensional center plane surface roughness meter (model ET-30HK) and a three-dimensional roughness analyzer (SPA-11) manufactured by Kosaka Laboratory Ltd., release The center surface average roughness (SRa) of the surfaces of the surface and the adhesive surface was measured by the stylus method under the following conditions.
The conditions were as follows, and the average value of 20 measurements was taken as the value.
Stitch tip radius: 0.5 μm
Stylus pressure: 20mg
Cut-off value: 80 μm
Measurement length: 1000 μm
Longitudinal magnification: 5000 times Measurement speed: 100 μm / s
Measurement interval: 2 μm

(3) Evaluation of adhesiveness It measured by the following method based on the JIS-Z-0237 (2000) adhesive tape * adhesive sheet test method.
As an adherend, an acrylic plate (Mitsubishi Rayon Co., Ltd .: Acrylite 3 mm thick) 50 mm × 150 mm is prepared, and a test piece is 25 mm in the winding direction at the time of film production and 180 mm in the direction perpendicular thereto. A piece was cut out, and using a rubber roll having a mass of 2000 g (with a spring hardness of 80 Hs on the roller surface and a width of 45 mm and a diameter (including the rubber layer) of 95 mm, covered with a rubber layer having a thickness of 6 mm), The test piece was reciprocated once at a speed of 5 mm / sec. After crimping, the initial one is left for 30 minutes in an environment of a temperature of 23 ° C. and a relative humidity of 65%, and the time left for 24 hours is 300 mm using “Tensilon” (UTM-IIIL) manufactured by Toyo Seiki Co., Ltd. The resistance value when peeled while maintaining an angle of 180 degrees at a speed of / min was defined as adhesive strength [cN / 25 mm]. At the time of measurement, a polyester sheet having a thickness of 190 μm and a size of 25 mm × 170 mm is prepared as a grip for the measurement sample, and the cellophane with a width of 15 mm is provided at the adhesive film side end of the measurement sample obtained by pressure-bonding the adhesive film and the acrylic plate. Affixed with tape and used as a grip for measurement. A schematic diagram of the measurement sample is shown in FIG. The measurement was performed three times for one sample, and the average value was defined as the adhesive strength of the sample.

(4) Film haze It measured using Nippon Denshoku Industries Co., Ltd. haze meter NDH-2000 based on the optical characteristic test method of JIS-K-7105 plastics.

(5) Evaluation of blocking resistance The adhesive film was cut into a size of 150 mm in length and 50 mm in width, overlapped with the adhesive surface and the release surface facing each other, and subjected to a 20 kg load for 7 days in a 40 ° C environment. I put it. Thereafter, the treated adhesive film was cut into 25 mm width × 100 mm length, and when the tensile tester Tensilon UT-IIIL manufactured by Toyo Seiki was used, the adhesive surface and the release surface were peeled 180 ° at a speed of 300 mm / min. The resistance value [cN / 25 mm] was measured.

(6) High-temperature handling property Evaluation of workability was performed by the following method assuming a line for attaching and peeling the adhesive film to the adherend.
Only the sample size was changed to the A4 size by the above-mentioned adhesive evaluation method, and after the adhesive film and the acrylic plate were bonded together, heat treatment was performed at 100 ° C., and then the peelability was evaluated manually.
1. Ease of pasting Evaluate workability when pasting with acrylic board ○: The film has sufficient waist and can be pasted easily. No wrinkling or lifting occurs when bonding.
X: The film has a low waist and tends to wrinkle and float when bonded.
2. Peelability ○: Easily peelable △: The film is slightly deformed at the time of peeling, but there is no problem in practical use ×: The film is stretched at the time of peeling and is difficult to peel off. It takes time to peel off

The results obtained from Examples and Comparative Examples are shown in Tables 1 and 2.
[Example 1]
(Creation of base material layer)
100 wt% of a homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: FLX80E4, tensile elastic modulus: 1500 MPa) was melt-extruded with a 60 mmφ single-screw extruder (L / D: 22.4) to form a base layer.
(Creation of adhesive layer)
100 wt% of a polyolefin-based elastomer (Mitsubishi Chemical Co., Ltd .: Zelas MC707) was melt-extruded with a 45 mmφ twin screw extruder (L / D: 19) to form an adhesive layer.
(Creation of release layer)
Propylene-ethylene block copolymer (manufactured by Sun Allomer: PC480A) 100 wt%
Was melt extruded with a 65 mmφ single screw extruder (L / D: 25) to form a release layer.
(Create film)
While the base material layer, the adhesive layer, and the release layer are melted in each extruder, lamination extrusion is performed in a three-layer T die (multi-manifold type, lip width 250 mm, lip gap 1 mm) at 250 ° C. It was. The extruded film is blown onto a casting roll at a temperature of 20 ° C. with an air knife, taken at a speed of 12 m / min, cooled and solidified, and a three-layer three-layer unstretched film having a substrate layer of 40 μm, an adhesive layer of 5 μm, and a release layer of 5 μm. Got.
As a result of evaluating the properties of this film, it has adhesiveness at room temperature, there is little fluctuation in adhesive strength over time, there is no blocking between the release layer and the adhesive layer, and it is easy to handle during high temperature processing. It was.

[Examples 2 and 3]
The base layer, the release layer, and the adhesive layer were the same as in Example 1, but the ratio of each layer was changed to the contents shown in Table 1, and three types and three layers of unstretched films were obtained by the same production method as in Example 1. .

[Examples 4, 5, and 6]
The base layer, the adhesive layer resin, and the production method were the same as in Example 1, but the release layer resin was changed to a mixture of propylene-ethylene block copolymer and random copolymer at the ratio shown in Table 1 to obtain three types and three layers. An unstretched film was obtained.

[Comparative Examples 1-4]
The resin of the base material layer and the adhesive layer and the production method were the same as in Example 1, but the ratio of each layer and the resin of the release layer were changed to those shown in Table 1 to obtain three types and three layers of unstretched films.

[Comparative Example 5]
The base layer, the release layer resin, and the ratio of each layer remain the same as in Example 1, and the adhesive layer resin is amorphous PP (Sumitomo Chemical: Tough Selenium H3522A, the heat of crystal fusion and the heat of crystallization is 28 J / g). To obtain an unstretched film of 3 types and 3 layers.

[Comparative Example 6]
The base layer, the adhesive layer resin, and the ratio of each layer remain the same as in Example 1, but the resin used for the release layer is changed to 100 wt% of homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: FLX80E4). An unstretched film was obtained.

[Comparative Example 7]
The resin of the adhesive layer and the release layer and the ratio of each layer remain the same as in Example 1, and the resin of the base material layer is changed to a propylene-1-butene copolymer (manufactured by Sumitomo Chemical: SPX78J1, tensile modulus: 530 MPa). Three types and three layers of unstretched films were obtained.

  The pressure-sensitive adhesive film of the present invention has little blocking between pressure-sensitive adhesive films, and particularly has little blocking even after the pressure-sensitive adhesive film is stored in a roll state, has excellent processability, and is foamed even when treated at a high temperature after being bonded to an adherend. Therefore, it can be used in a wide range of application fields such as synthetic resin plates, decorative plywood, metal plates and coated steel plates, as well as in the baking and printing of automobiles and printed circuit boards, making a great contribution to the industry.

It is a schematic diagram of a measurement sample.

Claims (1)

  An adhesive layer is laminated on one side of the polypropylene base material layer, and a release layer is laminated on the opposite side, and the average surface roughness SRa of the release layer surface is 0.200 μm or less, and the average surface of the adhesive layer surface The roughness SRa is 0.030 μm or less, the adhesive layer is mainly composed of a copolymer of polypropylene and an α-olefin having 3 or less carbon atoms, and the release layer is composed of a block copolymer or a block copolymer and a random copolymer. A pressure-sensitive adhesive film which is a mixture and has a haze value of 25% or less at a film thickness of 50 μm and a tensile elastic modulus of 90 MPa or more in a 100 ° C. environment.