How to recycle process film

Abstract

To provide a method of simply recycling a film for a process.SOLUTION: A method of recycling a film for a process includes the following processes 1-4, where the film for the process is a film for a process having an adhesive layer on a substrate, the substrate is a plastic film, the adhesive layer includes a thermoplastic elastomer and a plasticizer, and the thermoplastic elastomer includes a polymer having a block composed of a styrene monomer unit, and a block composed of a rubber monomer unit. Process 1 is a process of recovering the film for the process. Process 2 is a process of releasing the adhesive layer from the recovered film for the process. Process 3 is a process of recovering the plastic film which is the substrate. Process 4 is a process of recycling the recovered plastic film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for recycling process films. [Background technology]

[0002] In the process of manufacturing electronic devices, etc., a process may be performed in which components are temporarily fixed to an adhesive film, and after predetermined processing such as punching, the components are peeled off from the adhesive film. Such adhesive films are called process films.

[0003] Furthermore, optical films such as diffusion films, prism sheets, polarizing films, retardation films, hard coat films, and transparent conductive films may have adhesive films attached to their surfaces to prevent scratches during production, distribution, storage, etc. Such adhesive films are also called process films.

[0004] The process film has a structure in which an adhesive layer is provided on a substrate such as a plastic film, etc. As the process film, for example, Patent Documents 1 to 3 have been proposed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-292959 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-254789 [Patent Document 3] Japanese Patent Application Publication No. 11-129401 Summary of the Invention [Problem to be solved by the invention]

[0006] After a predetermined process and time has passed, the process film is peeled off from the part, etc. In order to reduce the burden on the environment, it is desirable that used process film be recycled. However, as in Patent Documents 1 and 2, general process films do not take into consideration recycling at all.

[0007] In the process film of Patent Document 3, the adhesive constituting the adhesive layer is a water-dispersible adhesive, so that the adhesive can be removed from the substrate by washing with water, and the substrate can be recycled. However, the process film of Patent Document 3 is limited to adhesives that are water-dispersible, and therefore, depending on the materials of the substrate and adherend, it is not possible to improve the adhesion between the substrate and the adhesive layer, or between the adhesive layer and the adherend, and therefore it lacks versatility.

[0008] An object of the present invention is to provide a method for easily recycling process films. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides the following [1] to

[10] . [1] A method for recycling a process film, comprising the following steps 1 to 4, wherein the process film is a process film having an adhesive layer on a substrate, the substrate is a plastic film, the adhesive layer contains a thermoplastic elastomer and a plasticizer, and the thermoplastic elastomer contains a polymer having a block composed of styrene monomer units and a block composed of rubber monomer units. Step 1: A step of recovering the process film. Step 2: Peeling off the adhesive layer from the recovered process film. Step 3: Recovering the plastic film base material. Process 4: The collected plastic film is recycled. [2] The method for recycling a process film according to [1], wherein the peel strength of the process film to soda glass at a 180° peeling angle and a peeling speed of 300 mm / min is 0.001 N / cm or more and 0.1 N / cm or less. [3] A method for recycling a process film according to [1] or [2], wherein the adhesive layer has a width of 25 mm, a thickness of 25 μm, and a breaking elongation of 300% or more but less than 2000% at a tensile speed of 200 mm / min. [4] The method for recycling a process film according to any one of [1] to [3], wherein the peel strength between the adhesive layer and the substrate at a 90° peel angle and a peel speed of 50 mm / min is 0.01 N / cm or more and 0.6 N / cm or less. [5] The method for recycling a film for process use according to any one of [1] to [4], wherein the plastic film is a polyester film. [6] The method for recycling a film for use in processes according to any one of [1] to [5], wherein the thermoplastic elastomer is at least one selected from SIS, SBS, SEBS, SEPS, SEEPS, and modified products thereof. [7] The method for recycling a film for processing according to any one of [1] to [6], wherein the plasticizer is at least one selected from naphthenic oil and liquid paraffin. [8] The method for recycling a process film according to any one of [1] to [7], wherein the content of the plasticizer in the adhesive layer is 5 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the thermoplastic elastomer. [9] The method for recycling a process film according to any one of [1] to [8], wherein in step 2, the peel angle between the substrate and the adhesive layer is 5° or more and 135° or less.

[10] The method for recycling a film for process use according to any one of [1] to [9], further comprising a step of recycling the recovered adhesive layer. [Effects of the Invention]

[0010] According to the present invention, process films can be easily recycled. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing one embodiment of the process film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the process film recycling method of the present invention will be described.

[0013] [How to recycle process film] The process film recycling method of the present invention is a process film recycling method comprising the following steps 1 to 4, characterized in that the process film is a process film having an adhesive layer on a substrate, the substrate is a plastic film, the adhesive layer contains a thermoplastic elastomer and a plasticizer, and the thermoplastic elastomer contains a polymer having a block composed of styrene monomer units and a block composed of rubber monomer units. Step 1: A step of recovering the process film. Step 2: Peeling off the adhesive layer from the recovered process film. Step 3: Recovering the plastic film base material. Process 4: The collected plastic film is recycled.

[0014] (Process 1) Step 1 is a step of recovering the processing film of the present invention, which will be described later. The processing film to be recovered is a used processing film. Therefore, the processing film to be recovered does not have a release sheet. It is preferable to recycle the release sheet via a separate route.

[0015] The process film collected in step 1 may be in the form of a roll or sheets.

[0016] (Process 2) Step 2 is a step of peeling off the adhesive layer from the recovered film for processing. In step 2, the adhesive layer is peeled off from the processing film, allowing the plastic film alone to be collected.

[0017] A method for peeling the adhesive layer from the process film includes peeling the adhesive layer from the edge of the process film, and then pulling the adhesive layer from the edge to peel the adhesive layer from the process film. As described below, the process film of the present invention is characterized in that it has an adhesive layer on a substrate, the substrate is a plastic film, the adhesive layer contains a thermoplastic elastomer and a plasticizer, and the thermoplastic elastomer contains a polymer having a block consisting of a styrene monomer unit and a block consisting of a rubber monomer unit.Since the adhesive strength between the adhesive layer and the substrate and the breaking elongation of the adhesive layer are within an appropriate range, when the adhesive layer is peeled from the process film, the adhesive layer and the substrate can be easily separated without breaking.

[0018] In step 2, when peeling the adhesive layer from the process film, the peel angle between the substrate and the adhesive layer is preferably 5° or more and 135° or less, more preferably 7° or more and 120° or less, even more preferably 9° or more and 100° or less, and even more preferably 10° or more and 90° or less. A peel angle of 5° or more makes it possible to easily and efficiently peel the adhesive layer from the substrate, and a peel angle of 135° or less makes it possible to make the adhesive layer less likely to break when peeled.

[0019] Furthermore, it is preferable to recover the peeled adhesive layer in step 2. The adhesive layer recovered in step 2 may be in the form of a roll or a sheet, and is preferably recovered in the same form as the process film recovered in step 1.

[0020] (Step 3) Step 3 is a step of recovering the plastic film substrate. Since a part of the adhesive layer may remain on the plastic film, step 3 may include a step of washing with water, a solvent, or the like.

[0021] To improve the workability of recycling, steps 1 to 3 are preferably carried out in the form of a roll as follows. In step 1, the process film is collected in the form of a roll. In step 2, the adhesive layer is peeled off while the rolled process film is being fed from the roll. In step 3, the plastic film is collected in roll form. Furthermore, in step 2, when the adhesive layer is peeled off while the rolled process film is being fed from the roll, the adhesive layer is preferably collected in a rolled state.

[0022] (Step 4) Step 4 is the process of recycling the collected plastic film.

[0023] Methods for recycling plastic films include material recycling, chemical recycling, and thermal recycling, with material recycling being preferred.

[0024] (Step 5) The process for recycling a process film of the present invention preferably further comprises, as step 5, a step of recycling the recovered adhesive layer.

[0025] Methods for recycling the adhesive layer include material recycling, chemical recycling, and thermal recycling, of which material recycling is preferred. Examples of material recycling methods include powdering the recovered adhesive layer, dissolving the powdered adhesive layer in a solvent, and then reusing the resulting coating solution for coating. Methods for powdering the adhesive layer include physically pulverizing the adhesive layer by cutting or the like, and pulverizing the adhesive layer by heating and melting it.

[0026] <Processing film> In the present invention, the process film is a process film having an adhesive layer on a substrate, characterized in that the substrate is a plastic film, the adhesive layer contains a thermoplastic elastomer and a plasticizer, and the thermoplastic elastomer contains a polymer having a block composed of styrene monomer units and a block composed of rubber monomer units.

[0027] Fig. 1 is a cross-sectional view showing one embodiment of the process film of the present invention. The process film 100 in Fig. 1 has an adhesive layer 20 on a plastic film 10 as a substrate. The process film 100 in Fig. 1 has a release sheet 30 on the side of the adhesive layer 20 opposite the plastic film. The process film may be in the form of a roll or a sheet.

[0028] (Plastic film (base material)) In the present invention, the process film uses a plastic film as the substrate. Adhesive layers do not easily penetrate into plastic films. Therefore, using a plastic film as the substrate makes it easier to recycle the substrate. On the other hand, if the substrate is paper or fiber, the adhesive layer and the like easily penetrate into the paper or fiber, making it difficult to recycle the substrate. Furthermore, by using a plastic film as the substrate, the process film can be made easier to handle and more durable.

[0029] Resins constituting plastic films include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polycarbonate; polyolefins such as polyethylene and polypropylene; polystyrene; triacetyl cellulose; poly(meth)acrylate; polyvinyl chloride; and the like. Among these resins, polyester is preferred. That is, polyester films are preferred as plastic films. Polyester films are preferred because of their excellent mechanical strength, dimensional stability, and transparency. Furthermore, among polyester films, biaxially oriented polyester films are preferred, and biaxially oriented polyethylene terephthalate films are more preferred. The surface of the plastic film may be corona discharge treated.

[0030] From the viewpoint of handling and strength, the thickness of the plastic film is preferably 10 μm or more and 500 μm or less, more preferably 15 μm or more and 250 μm or less, and even more preferably 20 μm or more and 100 μm or less.

[0031] <Peel strength> In the present invention, the peel strength of the process film to soda glass at a 180° peel angle and a peeling speed of 300 mm / min is preferably 0.001 N / cm or more and 0.1 N / cm or less, more preferably 0.005 N / cm or more and 0.05 N / cm or less, even more preferably 0.008 N / cm or more and 0.04 N / cm or less, and even more preferably 0.01 N / cm or more and 0.03 N / cm or less. A peel strength of 0.001 N / cm or more can facilitate good adhesion between the process film and the adherend, while a peel strength of 0.1 N / cm or less can reduce the force required to peel the process film from the adherend, facilitating improved peeling workability. In addition, used process films are sometimes collected in roll form. When recycling the substrate of a used process film wound into a roll, it is necessary to unwind the used process film from the roll. A peel strength of 0.1 N / cm or less makes the aforementioned unwinding easier, which can help improve the workability of recycling.

[0032] In the present invention, the peel strength of the process film means the peel strength from soda glass when peeled at 180° at a peel rate of 300 mm / min. The peel strength can be measured by the method described in the examples. As the soda glass, soda glass (thickness: 1.1 mm) manufactured by Hiraoka Glass Industry Co., Ltd. can be used.

[0033] The peel strength of the process film can be adjusted by the composition of the adhesive layer, etc. For example, if the content of plasticizer is increased, the adhesive layer will contain more components that do not contribute to adhesive strength, which tends to decrease the peel strength, while if the content of plasticizer is decreased, the peel strength tends to increase.

[0034] (Adhesive layer) In the present invention, the adhesive layer of the process film contains a thermoplastic elastomer and a plasticizer, and the thermoplastic elastomer must contain a polymer having a block consisting of a styrene monomer unit and a block consisting of a rubber monomer unit. The adhesive layer having the above-described structure can set the peel strength of the process film within the above-described range, improving the adhesion between the process film and the adherend, the ease of peeling from the adherend, and the ease of recycling. Furthermore, since the adhesive strength between the adhesive layer and the substrate and the breaking elongation of the adhesive layer can be set within appropriate ranges as described below, the adhesive layer can be easily separated from the substrate without breaking when peeled from the process film, particularly in the above-described step 2, improving the ease of recycling.

[0035] In the thermoplastic elastomer of the present invention, the content of the polymer having a block consisting of a styrene monomer unit and a block consisting of a rubber monomer unit is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 99% by mass or more, and particularly preferably 100% by mass.

[0036] In the present invention, the polymer having a block consisting of a styrene monomer unit and a block consisting of a rubber monomer unit is preferably at least one selected from SIS, SBS, SEBS, SEPS, SEEPS, SI, SB, SEP and modified products thereof, more preferably at least one selected from SIS, SBS, SEBS, SEPS, SEEPS and modified products thereof, and even more preferably at least one selected from SEBS and modified products of SEBS, from the viewpoint of making it easier to adjust the peel strength of the process film to the above range. The modified product is preferably an acid modified product, more preferably a maleic acid modified product.

[0037] In the present invention, the weight average molecular weight of the thermoplastic elastomer is preferably 15,000 or more and 500,000 or less, more preferably 100,000 or more and 500,000 or less, from the viewpoint of easily adjusting the peel strength of the process film to fall within the above range. In the present invention, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted into polystyrene.

[0038] In the present invention, the plasticizer is preferably one or more selected from naphthenic oil and liquid paraffin, more preferably liquid paraffin, from the viewpoint of making it easier to adjust the peel strength of the process film to the above range and also to make it easier to adjust the breaking elongation of the adhesive layer and the peel strength between the substrate and the adhesive layer to the ranges described below. The naphthenic oil preferably has a flash point of 100°C or higher and 300°C or lower, more preferably 150°C or higher and 280°C or lower. The naphthenic oil preferably has a pour point of -30°C or higher and -5°C or lower, more preferably -25°C or higher and -10°C or lower. The naphthenic oil preferably has a specific gravity of 0.83 or higher and 0.87 or lower, more preferably 0.837 or higher and 0.868 or lower. The naphthenic oil preferably has a carbon number of 21 or higher and 35 or lower, more preferably 25 or higher and 33 or lower. The flash point of liquid paraffin is preferably 100°C or higher and 300°C or lower, more preferably 150°C or higher and 280°C or lower. The pour point of liquid paraffin is preferably -30°C or higher and -5°C or lower, more preferably -25°C or higher and -10°C or lower. The specific gravity of liquid paraffin is preferably 0.89 or higher and 0.91 or lower, more preferably 0.8917 or higher and 0.9065 or lower. The carbon number of liquid paraffin is preferably 21 or higher and 35 or lower, more preferably 25 or higher and 33 or lower.

[0039] In the present invention, the content of the plasticizer is preferably 5 parts by mass or more and 300 parts by mass or less, more preferably 10 parts by mass or more and 290 parts by mass or less, even more preferably 20 parts by mass or more and 280 parts by mass or less, even more preferably 30 parts by mass or more and 270 parts by mass or less, even more preferably 40 parts by mass or more and 260 parts by mass or less, and particularly preferably 50 parts by mass or more and 250 parts by mass or less, per 100 parts by mass of the thermoplastic elastomer, from the viewpoint of making it easier to set the peel strength of the process film within the above range and also making it easier to set the breaking elongation of the adhesive layer and the peel strength between the substrate and the adhesive layer within the ranges described below. Furthermore, particularly from the viewpoint of making it easier to prevent contamination of the adherend due to migration of the plasticizer, the content of the plasticizer is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 95 parts by mass or less, even more preferably 20 parts by mass or more and 90 parts by mass or less, even more preferably 30 parts by mass or more and 85 parts by mass or less, still more preferably 40 parts by mass or more and 70 parts by mass or less, and particularly preferably 50 parts by mass or more and 65 parts by mass or less, relative to 100 parts by mass of the thermoplastic elastomer. Furthermore, particularly from the viewpoint of making it easier to maintain the breaking elongation, the content of the plasticizer is preferably more than 100 parts by mass and not more than 300 parts by mass, more preferably 110 parts by mass or more and not more than 290 parts by mass, even more preferably 120 parts by mass or more and not more than 280 parts by mass, still more preferably 130 parts by mass or more and not more than 270 parts by mass, still more preferably 140 parts by mass or more and not more than 260 parts by mass, and particularly preferably 150 parts by mass or more and not more than 250 parts by mass, relative to 100 parts by mass of the thermoplastic elastomer.

[0040] In the present invention, the adhesive layer preferably further contains a curing agent. As the curing agent, an isocyanate-based curing agent, an epoxy-based curing agent, or an amine-based curing agent is preferred, and an isocyanate-based curing agent is more preferred. By containing a curing agent, the peel strength between the plastic film and the adhesive layer can be adjusted, and unintentional peeling of the adhesive layer from the substrate can be easily prevented.

[0041] In the present invention, the thickness of the adhesive layer is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, and even more preferably 15 μm or more and 30 μm or less, from the viewpoint of making it easier to set the peel strength of the process film within the above range and to make it easier to set the breaking elongation of the adhesive layer and the peel strength between the substrate and the adhesive layer within the ranges described below.

[0042] <Breaking elongation of adhesive layer> The breaking elongation of the adhesive layer when it is 25 mm wide, 25 μm thick, and at a speed of 200 mm / min is preferably 300% or more and less than 2000%, preferably 400% or more and 1800% or less, more preferably 600% or more and 1600% or less, even more preferably 800% or more and 1500% or less, and particularly preferably 1000% or more and 1400% or less. A breaking elongation of 300% or more makes it possible to easily peel the adhesive layer without breaking it when peeling it from the process film in the above-mentioned step 2, and thus facilitates improving the workability of recycling. Furthermore, a peel elongation of less than 2000% makes it possible to prevent the release layer from stretching more than necessary when peeling the adhesive layer from the process film in the above-mentioned step 2, and therefore facilitates reducing the energy required for peeling, and therefore reduces the peel strength, and thus facilitates improving the workability of recycling. The breaking elongation of the adhesive layer can be adjusted by the composition of the adhesive layer, etc. For example, increasing the content of plasticizer tends to increase the breaking elongation of the adhesive layer, while decreasing the content of plasticizer tends to decrease the breaking elongation of the adhesive layer. By increasing the amount of plasticizer added, the cohesive strength of the adhesive layer decreases and the breaking elongation increases.

[0043] In the present invention, the breaking elongation of the adhesive layer means the breaking elongation at a width of 25 mm, a thickness of 25 μm, and a pulling speed of 200 mm / min. The breaking elongation of the adhesive layer can be measured by the method described in the examples.

[0044] <Peel strength between adhesive layer and substrate> The peel strength between the adhesive layer and the substrate at a 90° peel angle and a peel speed of 50 mm / min is preferably 0.01 N / cm or more and 0.6 N / cm or less, more preferably 0.02 N / cm or more and 0.5 N / cm or less, even more preferably 0.03 N / cm or more and 0.4 N / cm or less, even more preferably 0.04 N / cm or more and 0.3 N / cm or less, and particularly preferably 0.05 N / cm or more and 0.2 N / cm or less. A peel strength of 0.01 N / cm or more between the adhesive layer and the substrate can help prevent the adhesive layer from accidentally peeling off from the substrate when using or recycling the processing film. Also, a peel strength of less than 0.6 N / cm between the adhesive layer and the substrate can help prevent the adhesive layer from breaking when peeling it off from the processing film in step 2, which can help improve the workability of recycling. The peel strength between the adhesive layer and the substrate can be adjusted by the composition of the adhesive layer, etc. For example, if the content of plasticizer is increased, the adhesive layer contains more components that do not contribute to adhesive strength, and therefore the peel strength between the adhesive layer and the substrate tends to be smaller, whereas if the content of plasticizer is reduced, the peel strength between the adhesive layer and the substrate tends to be larger.

[0045] In the present invention, the peel strength between the adhesive layer and the substrate means the peel strength at a 90° peel angle and a peel speed of 50 mm / min. The peel strength between the adhesive layer and the substrate can be measured by the method described in the examples.

[0046] (Release sheet) In the present invention, the process film may have a release sheet on the side of the adhesive layer opposite the plastic film. By having a release sheet, the process film can be easily handled during storage and distribution. When the process film is used, the release sheet is peeled off.

[0047] Examples of the release sheet include plastic films, paper, etc. The release sheet may be a plastic film, paper, etc. whose surface has been treated with a release agent such as silicone to improve releasability. [Example]

[0048] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0049] 1. Measurement and evaluation 1-1. Peel strength of film for processing The process films of the Examples and Comparative Examples were cut into test pieces with a width of 25 mm and a length of 150 mm. The release sheet was peeled from the test piece, and the adhesive layer of the process film was placed face-to-face on a soda glass plate (manufactured by Hiraoka Glass Industry Co., Ltd., thickness: 1.1 mm). A 2 kg rubber roller was rolled back and forth from the process film side to bond the two together. The peel strength of the process film was measured using a tensile tester ("Autograph AGS-5NJ," manufactured by Shimadzu Corporation) at 180° peeling and a peeling speed of 300 mm / min. The measurement environment was a temperature of 23°C ± 5°C and a relative humidity of 40 to 65%. The measurement results are summarized in Table 1.

[0050] 1-2. Breaking elongation of adhesive Using the adhesive layer coating liquid used in the Examples and Comparative Examples, a single layer adhesive film having a thickness of 25 μm was prepared, and this was cut into a width of 25 mm and a length of 150 mm to prepare a test piece. The test pieces were subjected to a tensile test at a tensile speed of 200 mm / min using a tensile tester ("Autograph AGS-5NJ", manufactured by Shimadzu Corporation), and the breaking elongation of each adhesive layer was measured at a width of 25 mm and a thickness of 25 μm. The measurement environment was a temperature of 23°C ± 5°C and a relative humidity of 40 to 65%. The measurement results are summarized in Table 1.

[0051] 1-3. Peel strength between adhesive layer and substrate The process films of the Examples and Comparative Examples were cut into a width of 25 mm and a length of 150 mm to prepare test specimens. The substrate side of the test specimen was attached to a base with double-sided tape and then fixed, and the release sheet was peeled off. Next, the adhesive layer was peeled off from the substrate by approximately 1 cm from the edge. The edge of the peeled adhesive layer was fixed to the chuck of a tensile tester ("Autograph AGS-5NJ", manufactured by Shimadzu Corporation), and the adhesive layer was peeled off from the substrate at a 90° angle at a peeling rate of 50 mm / min, and the peel strength between the adhesive layer and the substrate was measured. The measurement environment was a temperature of 23°C ± 5°C and a relative humidity of 40 to 65%. The measurement results are summarized in Table 1.

[0052] 2. Preparation of process film [Example 1] The adhesive layer coating solution 1 described below was applied to one side of a 38 μm thick transparent polyester film (Lumirror 38S10, manufactured by Toray Industries, Inc.) and dried at 100° C. for 60 seconds to form an adhesive layer with a thickness of 25 μm. Next, a 25 μm thick silicone-treated release sheet (SP-PET O3-25-BU, manufactured by Mitsui Chemicals Tocello Co., Ltd.) was superimposed on the formed adhesive layer as a release sheet, and the two were bonded together using a laminator to obtain the process film of Example 1. <Coating liquid 1 for adhesive layer> Thermoplastic elastomer: Tuftec H1053 (SEBS, manufactured by Asahi Kasei Corporation) 30 parts by weight Plasticizer: Super Oil M10 (liquid paraffin, pour point -12.5°C, manufactured by ENEOS Corporation) 70 parts by mass Solvent: Toluene (appropriate amount) [Example 2] A casting film of Example 2 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using the adhesive layer coating liquid 2 described below. <Adhesive layer coating liquid 2> Thermoplastic elastomer: Tuftec H1053 (SEBS, manufactured by Asahi Kasei Corporation) 26 parts by weight Thermoplastic elastomer: Tuftec M1911 (maleic acid-modified SEBS, manufactured by Asahi Kasei Corporation) 13 parts by weight Plasticizer: PW-32 (liquid paraffin, pour point -17.5°C, manufactured by Idemitsu Kosan Co., Ltd.) 59 parts by mass Hardener: Coronate HL (isocyanate hardener, manufactured by Tosoh Corporation, solid content 75%) 0.25 parts by mass Solvent: Toluene (appropriate amount)

[0053] [Example 3] A film for processing of Example 3 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using the following adhesive layer coating liquid 3. <Adhesive layer coating liquid 3> Thermoplastic elastomer: Tuftec H1053 (SEBS, manufactured by Asahi Kasei Corporation) 30 parts by weight Plasticizer: PW-32 (liquid paraffin, pour point -17.5°C, manufactured by Idemitsu Kosan Co., Ltd.) 70 parts by mass Solvent: Toluene (appropriate amount)

[0054] [Example 4] A casting film of Example 4 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using the following adhesive layer coating liquid 4. <Adhesive layer coating liquid 4> Thermoplastic elastomer: Tuftec H1053 (SEBS, manufactured by Asahi Kasei Corporation) 100 parts by mass Plasticizer: PW-32 (liquid paraffin, pour point -17.5°C, manufactured by Idemitsu Kosan Co., Ltd.) 50 parts by mass Solvent: Toluene (appropriate amount)

[0055] [Comparative Example 1] A film for processing of Comparative Example 1 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using Coating Solution 5 for Adhesive Layer described below. <Coating liquid for adhesive layer 5> Thermoplastic elastomer: Tuftec M1911 (maleic acid-modified SEBS, manufactured by Asahi Kasei Corporation) 100 parts by mass Solvent: Toluene (appropriate amount)

[0056] Comparative Example 2 A film for processing of Comparative Example 2 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using Coating Solution 6 for Adhesive Layer described below. <Adhesive layer coating liquid 6> Adhesive: SK Dyne 1439U (acrylic adhesive, manufactured by Soken Chemical & Engineering Co., Ltd.) 100 parts by weight Hardener: E-50C (epoxy hardener, manufactured by Soken Chemical & Engineering Co., Ltd.) 1.5 parts by mass Solvent: Ethyl acetate (appropriate amount)

[0057] Comparative Example 3 A processing film of Comparative Example 3 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using Coating Solution 7 for Adhesive Layer described below. <Adhesive layer coating liquid 7> Adhesive: KP-1405 (acrylic adhesive, manufactured by Nippon Carbide Industries Co., Ltd.) 100 parts by weight Hardener: CK-102 (isocyanate hardener, manufactured by Nippon Carbide Industries Co., Ltd.) 1.5 parts by mass Solvent: Ethyl acetate (appropriate amount)

[0058] Comparative Example 4 A film for processing of Comparative Example 4 was obtained in the same manner as in Example 1, except that the adhesive layer was formed using Coating Solution 8 for Adhesive Layer described below. <Adhesive layer coating liquid 8> Adhesive: SK Dyne 2094 (acrylic adhesive, manufactured by Soken Chemical & Engineering Co., Ltd.) 100 parts by weight Hardener: E-5C (epoxy hardener, manufactured by Soken Chemical & Engineering Co., Ltd.) 2.7 parts by mass Solvent: Ethyl acetate (appropriate amount)

[0059] [Table 1]

[0060] The results in Table 1 confirm that the method for recycling process films of the present invention makes it possible to easily recycle process films. [Explanation of symbols]

[0061] 10: Plastic film 20: Adhesive layer 30: Release sheet 100: Processing film

Claims

1. A method for recycling process films, comprising the following steps 1 to 4: The process film is a process film having an adhesive layer on a substrate, the substrate is a plastic film, the adhesive layer contains a thermoplastic elastomer and a plasticizer, The method for recycling a process film, wherein the thermoplastic elastomer comprises a polymer having a block consisting of a styrene monomer unit and a block consisting of a rubber monomer unit. Step 1: A step of recovering the process film. Step 2: A step of peeling the adhesive layer from the edge of the process film, and pulling the adhesive layer using the peeled edge as a trigger to separate the adhesive layer from the recovered process film. Step 3: A step of recovering the plastic film substrate. Step 4: Recycle the collected plastic film.

2. 2. The method for recycling a process film according to claim 1, wherein the process film has a peel strength to soda glass at a 180° peel angle and a peel speed of 300 mm / min of 0.001 N / cm or more and 0.1 N / cm or less.

3. 3. The method for recycling a process film according to claim 1, wherein the adhesive layer has a breaking elongation of 300% or more and less than 2000% when the adhesive layer has a width of 25 mm, a thickness of 25 μm, and a tensile speed of 200 mm / min.

4. The method for recycling a process film according to any one of claims 1 to 3, wherein the peel strength between the adhesive layer and the substrate at a 90° peel angle and a peel speed of 50 mm / min is 0.01 N / cm or more and 0.6 N / cm or less.

5. 5. The method for recycling process films according to claim 1, wherein the plastic film is a polyester film.

6. The method for recycling a process film according to any one of claims 1 to 5, wherein the thermoplastic elastomer is at least one selected from the group consisting of SIS, SBS, SEBS, SEPS, SEEPS, and modified products thereof.

7. 7. The method for recycling a process film according to claim 1, wherein the plasticizer is at least one selected from naphthenic oil and liquid paraffin.

8. The method for recycling a process film according to any one of claims 1 to 7, wherein the content of the plasticizer in the adhesive layer is 5 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the thermoplastic elastomer.

9. The method for recycling a process film according to any one of claims 1 to 8, wherein in step 2, a peel angle between the substrate and the adhesive layer is 5° or more and 135° or less.

10. The method for recycling a process film according to any one of claims 1 to 9, further comprising a step of recycling the recovered adhesive layer.

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