JP2006206805A - Masking film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a masking film excellent in removability even applying heat treatment after sticking, and capable of effectively suppressing adhesive deposit after releasing or migration of additives to an adherend. <P>SOLUTION: In the masking film obtained by extrusion-laminating a laminating layer on a substrate film, the laminating layer is composed of a non-crosslinking type olefinic thermoplastic elastomer having durometer D hardness in the range of 20-60, or in another embodiment, the laminating layer is composed of a mixture of 30-90 mass% styrenic thermoplastic elastomer and 70-10 mass% polyethylene or ethylene-α-olefin copolymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a masking film, and more particularly to a masking film used for an application that is peeled off after being subjected to heat treatment in a state of being adhered to an adherend.

  Conventionally, as a masking film for masking the surface of an article, a masking film provided with an adhesive layer made of an acrylic rubber-based or natural rubber-based rubber-based adhesive has been widely used.

In Patent Document 1, as a surface protective film that does not cause peeling failure or adhesive residue due to an increase in cohesive force of an adhesive layer when used for applications involving high-temperature heating, the MFR is 1 to 20 g / 10 min, and the haze value Describes a surface protective film provided with an adhesive layer made of a polyolefin-based resin having a content of 3.5% or less.
In Patent Document 2, as a surface protective film that protects an adherend surface such as a vehicle body painted surface of a vehicle and does not cause contamination or sticking of the adherend surface after peeling, styrene 1 to 50% by mass and a diene hydrocarbon are used. (A) layer having a composition of 99% to 50% by mass of a hydrogenated product of random copolymer consisting of 60% by mass and less than 40% by mass of polyolefin, and 1-50% by mass of styrene and a diene hydrocarbon A surface protective film formed by laminating a layer (B) which is a support layer having a composition of less than 60% by mass of a hydrogenated random copolymer consisting of 99 to 50% by mass and a polyolefin having a composition exceeding 40% by mass is described. ing.

Patent Document 3 discloses a catalyst-coated ionomer membrane (for example, a perfluorinated sulfonic acid polymer for the purpose of improving mechanical stability and protecting against membrane damage in a membrane electrode assembly of a fuel cell). A membrane electrode assembly is described which is provided with a protective film that can be preformed and heat-laminated or adhered to the membrane by adhesion. Examples of organic polymer materials constituting this protective film include polytetrafluoroethylene, PVDF, polyester, polyamide, copolyamide, polyamide elastomer, polyimide, polyurethane, polyurethane elastomer, silicone, silicone rubber, and silicone-based elastomer. During the lamination, the protective film becomes soft and can penetrate into the electrode layer on the ionomer membrane (see, in particular, paragraphs 0046 to 0050 and 0056 of Patent Document 3).
JP-A-5-239418 JP-A-7-241960 JP 2004-134392 A

  In recent years, as the field of application of masking films expands, there is a desire to use a process in which heat treatment is performed in a state where the masking film is attached to the surface of an article (that is, an adherend). In the case of a masking film provided with an adhesive layer made of a conventional rubber-based adhesive, additives such as tackifiers and oil for imparting viscoelasticity to the rubber move to the article side, and the masking film is peeled off. It is also a problem that the additive remains on the surface of the article even after the treatment. Such migration of the additive becomes even more remarkable when the masking film is subjected to heat treatment in a state where the masking film is adhered to the surface of the article.

However, the prior art described in the patent document does not provide a satisfactory solution to the problem.
Although the surface protective film described in Patent Document 1 is an adhesive layer, the initial 90 ° peel strength is only about 3 to 4 g / 25 cm. Therefore, the surface protective film is easily peeled off by a slight external force. The object which can be used as a film is very limited, and it is not easy to use such as positioning at the time of sticking and storage management of the stuck adherend.
The surface protective film described in Patent Document 2 is supposed to be “not contaminated with an adherend because the composition does not contain a low molecular weight tackifier resin, a softener, etc.” (see Paragraph 0005 of Patent Document 2). However, it is attached to protect the painted surface of the car body, and no consideration is given to heat resistance. In other words, since it does not correspond to the application of performing a heat treatment after the surface protective film is adhered, in the case where the heat treatment is performed after the adhesion, in addition to the low heat resistance of the surface protective film itself, There is a possibility that the cohesive force of the layer is lowered and re-peeling becomes difficult.
The protective film in the membrane electrode assembly described in Patent Document 3 is for the purpose of semi-permanent protection of the ionomer film, and is not configured so that the protective film can be easily peeled off from the ionomer film. It cannot be used as a masking film that is later peeled off as appropriate.

  The present invention has been made in view of the above circumstances, and is excellent in re-peelability even if heat treatment is performed after sticking, and further, the adhesive residue after peeling and the transfer of the additive to the adherend are transferred. It aims at providing the masking film which can be suppressed effectively.

  In order to solve the above-mentioned problem, a non-crosslinked olefin-based masking film obtained by extrusion laminating a laminate layer on a base film, wherein the laminate layer has a durometer D hardness of 20 to 60 A masking film comprising a thermoplastic elastomer is provided.

The present invention is also a masking film obtained by extrusion laminating a laminate layer on a base film, the laminate layer comprising 30 to 90% by mass of a styrenic thermoplastic elastomer and polyethylene or ethylene-α-olefin copolymer. A masking film comprising a mixture of 70 to 10% by mass of a polymer is provided.
In the styrene thermoplastic elastomer, the ratio of styrene is preferably 1 to 50% by mass.
Styrenic thermoplastic elastomers are styrene / butadiene / styrene block copolymers, styrene / isoprene / styrene block copolymers, styrene / ethylene / butylene / styrene block copolymers, styrene / butadiene / butylene / styrene block copolymers, styrene / ethylene / propylene / styrene. It is preferably at least one block copolymer selected from the group consisting of block copolymers.

  The masking film of the present invention is used for application to a solid electrolyte membrane of a fuel cell, for example, when an electrode layer is formed in a desired pattern on a solid electrolyte membrane as described in JP-A-2000-268829. It can be used for masking unnecessary layers. As the solid electrolyte membrane, for example, one made of a fluoropolymer having a sulfonic acid group can be used.

  According to the masking film of the present invention, the laminate layer has strong cohesive force at room temperature (15 to 25 ° C.) and does not exhibit tackiness. When heated, the laminate layer develops tackiness and reliably adheres to the adherend. Can do. Even if the cohesive strength of the laminate layer decreases after heat treatment, the cohesive strength rises again if cooled to room temperature, restoring the removability of the masking film, and easily peels off the adherend without leaving any adhesive residue. can do. Furthermore, since the additive causing the migration is not included, there is no problem of the migration of the additive to the adherend.

  The masking film according to the first aspect of the present invention is a masking film obtained by extrusion laminating a laminate layer on a base film, and the laminate layer has a durometer D hardness in the range of 20-60. It consists of a cross-linking type olefinic thermoplastic elastomer.

In the first aspect of the invention, in order to extrusion laminate the laminate layer onto the base film, the material constituting the base film must not melt at a temperature at which the material constituting the laminate layer melts. For this reason, the plastic contained in the base film preferably has a melting point of 130 ° C. or higher. Specific examples of the base film include plastic films such as polyesters such as polyethylene terephthalate (PET) and polyamides such as nylon. From the viewpoint of a high melting point, these films are preferably stretched uniaxially or biaxially. In particular, if the film is biaxially stretched, a film made of a polyolefin having a relatively low melting point such as polypropylene (PP) can also be used. Moreover, by setting it as a stretched film, the intensity | strength of a film becomes high and the protection performance of a to-be-adhered body improves.
In order to improve the adhesion between the laminate layer and the base film, the surface of the base film is subjected to a surface treatment such as corona discharge treatment as necessary, or an anchor coating agent is provided between the laminate layer and the base film. May be used.

  In the first aspect of the invention, an olefinic thermoplastic elastomer (hereinafter sometimes abbreviated as “TPO”. TPO = Thermoplastic Olefin elastomer) is a molecular constraining component (hard segment) that is polyethylene (PE) or polypropylene (PP ) Such as ethylene-propylene-diene terpolymer (EPDM) or ethylene propylene rubber (EPR) as a flexible component (soft segment) having rubber elasticity. System rubber (rubber component). Among these, TPO whose hard segment is polypropylene is preferable.

Olefin-based thermoplastic elastomers include cross-linked type and non-cross-linked type (for example, Kunihiko Mizumoto, “New development of olefin-based thermoplastic elastomer”, Molding, Vol. 12, No. 12) 755-759, 2000).
The crosslinking type is obtained by chemically crosslinking a rubber component with a resin component, and is produced by a so-called dynamic crosslinking technique in which a crosslinking reaction is performed in a kneaded state such as in an extruder. On the other hand, the non-crosslinking type includes a simple blend type that is a compound of a resin component and a rubber component, and a reactor type that simultaneously manufactures a resin component and a rubber component in a polymerization process.

Cross-linked TPO is superior in rubber elasticity and heat resistance to non-cross-linked TPO, but on the other hand, it is inferior in moldability and unsuitable for the development of adhesiveness. In contrast, non-crosslinked TPO has high rubber elasticity at room temperature and relatively low tackiness, but when heated, it increases plasticity and tackiness and is excellent in moldability.
Therefore, by using non-crosslinking type TPO, a laminate layer can be easily formed on the base film by extrusion lamination. Further, among the non-crosslinking type TPO, those having a durometer D hardness of 20 to 60 are used. As a result, the cohesive force is strong at room temperature (15 to 25 ° C.) and does not exhibit tackiness, and exhibits moderate tackiness when heated to a high temperature (for example, about 100 ° C.), and reliably adheres to the adherend. can do. Moreover, if it cools to normal temperature, the cohesion force of a laminate layer will rise again, it can peel easily from a to-be-adhered body, and there will be no adhesive residue. In addition, durometer D hardness is a value measured using the type D durometer prescribed | regulated to JISK7215.
When the durometer D hardness of TPO exceeds 60, it is not preferable because sufficient adhesive strength cannot be obtained before heating. Moreover, from the viewpoint of the moldability of the laminate layer, the melt flow rate (MFR) of TPO is preferably 1 to 10 g / 10 min.
The masking film of the first form has an advantage that the laminate layer is composed only of a polymer component and does not contain a low molecular component such as a tackifier or oil, so that there is no problem of transfer of the additive to the adherend. Have

  The masking film according to the second embodiment of the present invention is a masking film formed by extrusion laminating a laminate layer on a base film, and the laminate layer comprises 30 to 90% by mass of a styrene-based thermoplastic elastomer, polyethylene or It consists of a mixture with 70-10 mass% of ethylene-alpha-olefin copolymers, It is characterized by the above-mentioned.

In the second aspect of the invention, in order to extrusion laminate the laminate layer onto the base film, the material constituting the base film must not melt at a temperature at which the material constituting the laminate layer melts. For this reason, the plastic contained in the base film preferably has a melting point of 130 ° C. or higher. Specific examples of the base film include plastic films such as polyesters such as polyethylene terephthalate (PET) and polyamides such as nylon. From the viewpoint of a high melting point, these films are preferably stretched uniaxially or biaxially. In particular, if the film is biaxially stretched, a film made of a polyolefin having a relatively low melting point such as polypropylene (PP) can also be used. Moreover, by setting it as a stretched film, the intensity | strength of a film becomes high and the protection performance of a to-be-adhered body improves.
In order to improve the adhesion between the laminate layer and the base film, the surface of the base film is subjected to a surface treatment such as corona discharge treatment as necessary, or an anchor coating agent is provided between the laminate layer and the base film. May be used.

In the second aspect of the invention, a styrene-based thermoplastic elastomer (hereinafter sometimes referred to as “styrene-based TPE”. TPE = Thermoplastic Elastomer: thermoplastic elastomer) is polystyrene (PS) as a molecular constraint component (hard segment). As a flexible component (soft segment) having rubber elasticity, it has a rubber-based polymer such as polybutadiene, polyisoprene, hydrogenated polybutadiene, and hydrogenated polyisoprene.
In the styrene thermoplastic elastomer, the ratio of styrene (ratio of hard segments) is preferably 1 to 50% by mass. When the ratio of styrene exceeds 50% by mass, the melt tension becomes weak and film formation by extrusion lamination becomes difficult.

  Specific examples of the styrenic TPE include styrene / butadiene / styrene block copolymer (SBS), styrene / isoprene / styrene block copolymer (SIS), styrene / ethylene / butylene / styrene block copolymer (SEBS), and styrene / butadiene / butylene. / Styrene block copolymer (SBBS), styrene / ethylene / propylene / styrene block copolymer (SEPS), and the like.

Here, the polyethylene or the ethylene-α-olefin copolymer is added as an essential component in order to ensure the cohesive strength of the laminate layer at a high temperature (suppress the increase in adhesive strength). The polyethylene or ethylene-α-olefin copolymer preferably has a density of 910 to 970 kg / m ³ , and has a melt flow rate (MFR) of 4 to 20 g / 10 min from the viewpoint of moldability of the laminate layer. preferable.
Specific examples of polyethylene that can be used in this embodiment include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

The compounding ratio of the styrene TPE and the polyethylene or ethylene-α-olefin copolymer in the laminate layer is 70 to 10% by mass of polyethylene or ethylene-α-olefin copolymer with respect to 30 to 90% by mass of styrene TPE. As a result, the cohesive force is strong at room temperature (15 to 25 ° C.) and does not exhibit tackiness, and exhibits moderate tackiness when heated to a high temperature (for example, about 100 ° C.), and reliably adheres to the adherend. Can be worn. Moreover, if it cools to normal temperature, the cohesion force of a laminate layer will rise again, it can peel easily from a to-be-adhered body, and there will be no adhesive residue.
When the blending ratio of the styrene-based TPE exceeds 90% by mass, the adhesive force increases excessively during storage at high temperature or heat treatment, and re-peeling may be difficult. Moreover, since the initial adhesive force (adhesive force before heat processing) is weak when the compounding ratio of styrene type | system | group TPE is less than 30 mass%, alignment of a masking film becomes difficult and is unpreferable.
The masking film of the second form has an advantage that the laminate layer is composed only of a polymer component and does not contain a low molecular component such as a tackifier or oil, so that there is no problem of transfer of the additive to the adherend. Have

The masking film according to the first embodiment and the second embodiment of the present invention can be used for various applications, and in particular, the application in which the heat treatment is performed after the masking film is attached and the masking film is peeled off after the heat treatment. It is suitable for.
As a specific example, when an electrode is formed in a predetermined region on the surface of a solid electrolyte membrane for fuel cells (ion exchange membrane: PEM) made of a polymer electrolyte such as a fluoropolymer having a sulfonic acid group, the solid electrolyte membrane A masking film is adhered (for example, using a thermal laminator (Nakabayashi PACLAMI Pro PLP-325), and after thermal laminating at 100 ° C. for 10 minutes or 40 minutes according to processing conditions of temperature 120 ° C. and speed 6. ) After applying and drying a paste-like electrode material from an opening (window-like hole) having a desired shape provided in the masking film, the masking film is peeled off. By such an operation, an electrode having a desired shape can be formed on the solid electrolyte membrane.

  In order to clarify the effects of the present invention, a masking film of each embodiment of the present invention and a masking film serving as a comparative example were produced using the thermoplastic polymers shown in Tables 1 and 2 as laminate layers and evaluated. The method and results are described below.

(Manufacture of masking film)
A laminate layer (thickness: 25 μm) was laminated by extrusion lamination on a 75 μm thick base film made of a polyester film via a urethane anchor coating agent to obtain a masking film.

(Testing adhesive properties of masking film)
A sample having the configuration shown in FIG. 1 was prepared by the following procedure.
Two masking films 1 and 1 were prepared by punching the in-plane of the masking film 1 having an outer size of 120 mm × 120 mm into 60 mm × 60 mm and making a cut so as to be concentric. Two masking films 1 and 1 having two cuts are overlapped so that the laminate layer is on the inside and the base film is on the outside, heat-sealed on one side 1c and bound together, and the two masking films 1 bound together , 1 to insert the adherend 2 (100 mm × 100 mm PET film, thickness 38 μm), thermal laminating apparatus (manufactured by Meiko Shokai Co., Ltd., product name MS POUCH H-320Z, laminating speed is level 1-11 The masking films 1 and 1 were bonded to both surfaces of the adherend 2 by using the above.
A part of the inner frame 1a surrounded by the cut of one masking film 1 (the lower part in FIG. 1) is peeled off so as to be separated from the outer frame 1b outside the cut, and the inner frame 1a is partially peeled off. A strip-like PET film (thickness: 38 μm) having a width of 20 mm and a length of 50 mm was attached to the front end by a staple 4 as a knob piece 3 for a tensile test.
By pulling the knob piece 3 upward in FIG. 1, the resistance when the inner frame 1a of the masking film 1 is peeled off from the adherend 2 is measured with a load cell to determine the peeling strength (peeling speed: 300 mm / min, peel angle : 180 °).

(Preparation and testing of a masking film having a laminate layer made of an olefinic thermoplastic elastomer)
A masking film is produced using the olefinic thermoplastic elastomer (TPO) shown in Table 1, and a sample having the structure shown in FIG. The peel strength between the substrate and the adherend 2 was measured. The peel strength was measured immediately after the masking film 1 and the adherend 2 were adhered by thermal lamination (“before heat treatment”) and after heat treatment at 130 ° C. for 10 minutes (“after heat treatment”). (See Table 1 for results).
Further, after the heat treatment, the bonding state between the masking film 1 and the adherend 2 was visually observed, and when floating was observed, the numerical value of the peel strength was shown with a symbol “Δ”.

The manufacturers of TPO shown in Table 1 are as follows.
IDEMISUSU TPO E-2900: Idemitsu Kosan Co., Ltd. IDEMITSU TPO E-2740: Idemitsu Kosan Co., Ltd. IDEMITSU TPO R110MP: Idemitsu Kosan Co., Ltd. Zelas 7023: Mitsubishi Chemical Corporation Miralastomer 6030N: Mitsui Chemicals, Inc.

As shown in Table 1, by using non-crosslinking type TPO having a durometer D hardness in the range of 20 to 60 as the TPO constituting the laminate layer of the masking film, even before the heat treatment, after the heat treatment ( Even at 130 ° C. for 10 minutes, a masking film showing an appropriate peel strength could be obtained.
When the cross-linked TPO was used, extrusion lamination could not be processed, and the masking film could not be produced.

(Production and test of a masking film having a laminate layer containing a styrenic thermoplastic elastomer)
As shown in Table 2, a masking film having a laminate layer made of a styrenic thermoplastic elastomer and a masking film having a laminate layer made of a mixture of a styrenic thermoplastic elastomer and polyethylene were produced. In Table 2, the compounding ratio indicates a mass ratio (styrene-based thermoplastic elastomer / polyethylene).
Moreover, the sample of the structure shown in FIG. 1 was produced by the method shown to the said "adhesion characteristic test of a masking film" using the obtained masking film.

The manufacturers of the styrene thermoplastic elastomer and polyethylene shown in Table 2 are as follows.
Tuftec H1041: Asahi Kasei Chemicals Corporation Mirason 16P: Mitsui Chemicals, Inc. Sumikasen L705: Sumitomo Chemical Co., Ltd. Moretec 0818D: Idemitsu Kosan Co., Ltd.

  For each sample, the peel strength before applying the heat treatment and the peel strength after applying the heat treatment at a temperature of 100 ° C. for a predetermined time (10 minutes, 40 minutes and 60 minutes) were measured. The result is shown in the graph of FIG. The graph legend in FIG. 2 corresponds to the description in the “Graph legend” column of Table 2.

As shown in the graph, in the case of a masking film having a laminate layer made of a mixture of a styrenic thermoplastic elastomer and polyethylene, the peel strength can be increased even by heat treatment at 100 ° C. for about 1 hour (or more). Small and good peelability after heat treatment.
On the other hand, in the case of a masking film having a laminate layer consisting only of a styrene-based thermoplastic elastomer, when the heat treatment is performed at 100 ° C., the peel strength is greatly increased even if the heat treatment time is about 10 minutes, It became difficult.

  The present invention is suitable for applications that are peeled after being heat-treated in a state of being adhered to an adherend. For example, various materials are masked with a masking film and applied to the adherend, followed by drying and heat treatment. By applying a heat treatment such as thermosetting, the layer or film can be used in a method for forming a desired shape.

In the adhesion characteristic test of a masking film, it is the (a) top view and (b) sectional view which show the sample of a masking film. It is a graph of the example of a measurement which shows the influence of the heat processing with respect to the peeling strength of the masking film which has a laminate layer containing a styrene-type thermoplastic elastomer.

Explanation of symbols

1 ... Masking film.

Claims (6)

A masking film obtained by extrusion laminating a laminate layer on a base film,
The said laminated layer consists of a non-crosslinked type olefin type thermoplastic elastomer whose durometer D hardness is in the range of 20-60, The masking film characterized by the above-mentioned. A masking film obtained by extrusion laminating a laminate layer on a base film,
The said laminated layer consists of a mixture of 30-90 mass% of styrene-type thermoplastic elastomers, and 70-10 mass% of polyethylene or an ethylene-alpha-olefin copolymer, The masking film characterized by the above-mentioned.   The masking film according to claim 2, wherein the ratio of styrene in the styrene-based thermoplastic elastomer is 1 to 50% by mass.   Styrenic thermoplastic elastomers are styrene / butadiene / styrene block copolymers, styrene / isoprene / styrene block copolymers, styrene / ethylene / butylene / styrene block copolymers, styrene / butadiene / butylene / styrene block copolymers, styrene / ethylene / propylene / styrene. 4. The masking film according to claim 2, wherein the masking film is at least one block copolymer selected from the group consisting of block copolymers.   The masking film according to any one of claims 1 to 4, wherein the masking film is attached to a solid electrolyte membrane of a fuel cell.   6. The masking film according to claim 5, wherein the solid electrolyte membrane is made of a fluoropolymer having a sulfonic acid group.

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