JP2012188462A - Method for mounting polypropylene-based surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for mounting a polypropylene-based surface protective film which enables surface protection of an adherend with high sealability, airtightness and reliability, without concern of adhesive deposit from a self-adhesive layer at the time of opening, by completely sealing whole of the adherend such that the adherend to be surface-protected is nipped and wrapped around its periphery with a surface protective film excellent in transparency, environmental responsiveness and moderate flexibility, having quite-high adhesive force between self-adhesive surfaces thereof compared to adhesive force to the adherend, without employing a method of vacuum packaging or heat-seal packaging.SOLUTION: When the self-adhesive surfaces of the polypropylene-based surface protective film are pasted together, the peel strength (unit: N/25 mm) at the time of peeling is (i), and when the self-adhesive surface and the adherend are pasted together, the peel strength (unit: N/25 mm) at the time of peeling is (ii). Then the following relationships are satisfied: the (i) value is 5 N/25 mm or higher; and the ratio of (i) value to (ii) value is 3.0 or more.

Description

  The present invention relates to a method for mounting a polypropylene surface protective film. More specifically, the adhesive strength between the adhesive surfaces is extremely high as compared with the adhesion to the adherend, and the coated surface is made of a polypropylene surface protective film excellent in transparency, environmental compatibility, and appropriate flexibility. Adhesion to the adherend when opened by completely sealing the entire adherend without using vacuum packaging or heat-sealing packaging, by sandwiching the adherend from both sides and wrapping the surrounding area. The present invention relates to a method for mounting a polypropylene surface protective film that enables surface protection of an adherend with high sealing performance, airtightness, and reliability without fear of adhesive residue from a layer.

  Conventionally, for the purpose of preventing surface scratches, weathering deterioration, dust adhesion, etc. during long-term storage and transportation, such as resin bodies, metal bodies, and ceramic bodies molded into a flat or curved shape The pressure-sensitive adhesive film provided with the pressure-sensitive adhesive layer is referred to as a surface protective film, and the entire surface, or only the surface side of the adherend that is the surface protection object, or both the surface side and the back side, or A method of bonding to a part of the surface is taken. The example which bonded the surface protection film 4 which has the base material layer 2 and the adhesion layer 3 only on the one surface of the to-be-adhered body 1 in FIG. 3 is shown.

  In such a case, the surface protective film used may vary depending on the material and shape of the adherend to be surface protected, the required performance, and the like, and the composition and configuration of the surface protective film are usually 1) polyethylene terephthalate. (Simplified PET), polyvinyl chloride with a plasticizer blended (simply soft PVC), acrylic resin that exhibits adhesive performance on one side of a thermoplastic resin base film represented by polyolefin resin, etc. Coatable adhesive film obtained by coating and drying adhesive components such as copolymers, natural rubber, modified natural rubber, styrene block copolymers, and silicone copolymers by the solution method or emulsion method Or 2) a so-called self-adhesive obtained by laminating a thermoplastic resin constituting the substrate and a thermoplastic resin constituting the adhesive layer by a coextrusion method. Films and the like have been widely used (Patent Documents 1 to 6).

  At this time, the coating-type adhesive film of 1) is relatively easy to design and denature the adhesive component, and the quality design to obtain the appropriate adhesive performance according to the application is relatively easy. Has been extensively commercialized and has been adopted in many fields. However, in the production process, when the adhesive component was applied to the base film, an organic solvent for completely dissolving the adhesive as a coating solution and a surfactant for microdispersing the adhesive were added. An aqueous solvent is used. For this reason, there is a concern that a part of the substance is released into the atmosphere or rivers at the stage of the preparation process or the coating / drying process, which adversely affects the global environment.

In the case of the self-adhesive film of 2), a polyolefin resin such as polyethylene, polypropylene, ethylene / α-olefin copolymer, polybutene or polyhexene is usually used for the base material layer. In addition, the adhesive layer usually contains another type of low density ethylene / α-olefin copolymer, polyolefin resin such as ethylene / vinyl acetate copolymer, styrene block copolymer or silicone copolymer. Adopted and composed of various combinations of these base layer resin and adhesive layer resin. In addition, if necessary, in order to impart further tackiness and wettability to the pressure-sensitive adhesive layer, a low molecular weight component called a tackifier resin is added, or on the base material layer opposite to the pressure-sensitive adhesive layer. As the surface layer (outermost layer), a layer made of another thermoplastic resin is provided, or an antistatic agent, a lubricant, a release agent, a colorant, and other additives are blended with the same thermoplastic resin as the base material layer. A layer is provided.
As described above, the self-adhesive film employs a coextrusion method in which a resin component is melt-extruded for lamination. For this reason, considering the coextrusion suitability of each layer, the interlaminar adhesiveness, and the suitability for film formation at the time of filming, it is difficult to take a wide range of performance designs like the coating type adhesive film of 1) The reality is that the product is a combination of adhesive properties.

  Moreover, since the conventionally well-known adhesive resin and the adhesive component are employ | adopted for the surface protective film of the said structure 1) and 2), the design of an adhesive characteristic has a limit naturally. Therefore, the surface protection method focusing only on the adhesion performance to the adherend to be surface protected, i.e., on the entire surface or a part of the surface only on the surface side of the adherend or on both the surface side and the back surface side. A surface mainly used to prevent scratches, weathering deterioration, and dust adhesion on the surface of adherends that have been shaped into a flat or curved shape, only used in the method of bonding adhesive films. Limited to how protection is used. In addition, for the purpose of completely sealing the entire adherend, the mounting form as seen in vacuum packaging or heat sealing methods, that is, the two surface protection films are stacked so that the adhesive surfaces face each other. Or by folding the surface protective film so that the adhesive surfaces are on the inner surface side, and sandwiching the adherend to be surface protected between them, and bonding the adhesive surface of the surface protective film When the form surrounding the periphery is adopted, the peel strength when the adhesive surfaces of the surface protective film are bonded to each other and the peel strength of the adhesive surface from the adherend when opened reveals an ideal balance of adhesive strength. I couldn't. In other words, there is no concern about the adhesive residue phenomenon from the adhesive layer to the adherend when opened, and it is extremely difficult to make it possible to protect the surface of the adherend with high sealing performance, sealing performance, and reliability. It was.

Japanese Patent No. 3887402 JP 2001-301024 A JP 7-1681 A JP-A-5-98224 JP-A-8-323944 JP-A-8-253744

  The present invention is a polypropylene surface protection film having an extremely high adhesive force between adhesive surfaces as compared to the adhesion to an adherend, and excellent in transparency, environmental friendliness, and moderate flexibility. By sandwiching the adherend to be adhered from both sides and wrapping the surroundings, the entire adherend is completely sealed without taking vacuum packaging or heat seal packaging methods, and the adherend to the adherend when opened It is an object of the present invention to provide a method for mounting a polypropylene-based surface protective film that is capable of protecting the surface of an adherend with high sealing performance, airtightness, and reliability without concern about the adhesive residue from the adhesive layer.

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by adopting a mounting method using a surface protective film having a self-adhesive performance composed of a resin composition of a specific composition. It came to complete.

That is, in the present invention, the attachment form of the adherend to be surface-protected by bonding of the surface protective film is such that two polypropylene surface protective films are superposed such that the adhesive surfaces face each other, or 1 A sheet of polypropylene surface protective film is folded so that the adhesive surfaces are on the inner surface side, an adherend to be surface protected is sandwiched between the adhesive surfaces, and the adhesive surfaces of the polypropylene surface protective film are pasted together. It is a mounting method of a polypropylene-based surface protective film that takes a form of wrapping the periphery of the adherend together, peeling strength when peeling the adhesive surfaces of the polypropylene-based surface protective film (unit: N / 25 mm) is (i), and the peel strength (unit: N / 25 mm) at the time of peeling when the adhesive surface and the adherend are bonded is (ii), (i) In There 5N / 25 mm or more, about mounting method of the polypropylene-based surface protective film in a relationship ratio of 3.0 or more with respect to (ii) values of (i) values.
Furthermore, in the mounting method of the polypropylene-based surface protective film, the configuration of the polypropylene-based surface protective film is composed of at least two layers of a base material layer and an adhesive layer, and the base material layer is made of a resin mainly composed of polypropylene. And the adhesive layer contains 50 to 90 mol% of propylene-derived structural units, 6 to 23 mol% of ethylene-derived structural units, and 4 to 27 mol% of structural units derived from α-olefins having 4 to 10 carbon atoms (here And a propylene / ethylene / α-olefin copolymer (A) containing a propylene-derived structural unit, an ethylene-derived structural unit, and a C 4-10 α-olefin-derived structural unit in a total of 100 mol%) And propylene / ethylene / α-olefin copolymer (A) and polypropylene (B) It is preferred that the ratio of the blend is in the range of 98 / 2-70 / 30 by weight%.

  The method for mounting the polypropylene surface protective film of the present invention has a very high adhesive force between the adhesive surfaces as compared to the adhesion to the adherend, and is excellent in transparency, environmental friendliness and moderate flexibility. A packaging form that requires a large specific device for sealing, such as vacuum packaging and heat seal packaging, by sandwiching the substrate to be protected from both sides with a surface protection film. There is no need to take In addition, by adopting a polypropylene-based surface protective film having a specific adhesive property, the entire adherend is completely sealed, and there is a concern about the adhesive residue phenomenon from the adhesive layer to the adherend when opened. And a mounting method capable of protecting the surface of the adherend with high sealing performance, sealing performance and high reliability.

It is a schematic sectional drawing for demonstrating the mounting method of the polypropylene-type surface protection film in the Example and comparative example of this invention, and shows the aspect which wraps a to-be-adhered body with two polypropylene-type surface protection films. It is a schematic sectional drawing for demonstrating the mounting method of the polypropylene-type surface protection film in the Example and comparative example of this invention, and shows the aspect which wraps a to-be-adhered body with one polypropylene-type surface protection film. It is a schematic sectional drawing for demonstrating the pasting method of the conventional polypropylene type protective film, and the aspect which bonded the polypropylene type surface protective film only to the single side | surface of a to-be-adhered body is shown.

Next, the present invention will be described in detail.
The mounting method of the polypropylene-based surface protective film of the present invention is such that the adhesive surfaces of the two surface protective films face each other as a mounting form of an adherend that is surface-protected by bonding of the polypropylene-based surface protective film. The surface protection film is folded or folded so that the adhesive surfaces are on the inner surface side, and the adherend to be surface protected is sandwiched between the adhesive surfaces. Adopt a form that wraps the surroundings by bonding the faces together.

  In FIG. 1, two surface protective films 4 and 4 ′ are overlapped so that the adhesive surfaces (adhesive layers 3 and 3 ′) face each other, and the surface is formed between the adhesive surfaces (adhesive layers 3 and 3 ′). The attachment method of the surface protection film which took the form which wraps the periphery of the to-be-adhered body 1 by sticking the to-be-adhered body 1 protected, bonding adhesive surfaces (adhesive layer 3 and 3 ') together, and showing the periphery of the to-be-adhered body 1 is shown. Further, in FIG. 2, one surface protective film 4 is folded so that the adhesive surfaces (adhesive layer 3) are on the inner surface side, and the adherend 1 is surface-protected between the adhesive surfaces (adhesive layer 3). The attachment method of the surface protection film which took the form which wraps the periphery of the to-be-adhered body 1 by sticking adhesive surfaces (adhesion layer 3) together is shown.

  Regarding the method for mounting the polypropylene surface protective film of the present invention, the material to be adhered is a known resin body such as polyester resin, polycarbonate resin, polyamide resin, styrene resin, acrylic resin, phenol resin, iron, etc. There are no specific materials such as metal bodies such as stainless steel, copper, aluminum, metal oxides, metal plated paint bodies, silicon oxide compounds such as glass, ceramics, porcelain, semiconductor materials, and other ceramic bodies. is there. Further, the shape and the surface state are not particularly limited, including those formed into a flat shape, a curved surface shape or an indeterminate shape, a smooth surface shape or an uneven shape.

A major feature of the method for mounting the polypropylene-based surface protective film of the present invention is that the peel strength (unit: N / 25 mm) at the time of peeling when the adhesive surfaces are bonded to each other is (i), When the peel strength (unit: N / 25 mm) at the time of peeling when the adhesive surface and the adherend are bonded is (ii), (i) the value is 5 N / 25 mm or more, preferably 6 N / 25 mm or more. The ratio of (i) value to (ii) value is 3.0 or more, preferably 3.5 or more. (Note that the peel strength at this time is measured by bonding the adhesive surfaces of the surface protective film to the adherend according to JIS Z0237, or bonding the adhesive surfaces of the surface protective film to each other at 23 ° C. × Left for 1 day under 50% RH environmental condition and measurement evaluation using tensile strength measuring device under the same environmental condition, with (i) value measured by 90 degree peeling method, (ii) value In the case of the measurement, the 180 degree peeling method is used, and the tensile peeling speed at this time is 300 mm / min.)
At this time, the value (ii) is preferably 30 N / 25 mm or less. When this value is exceeded, a remarkable adhesive residue phenomenon may occur when the polypropylene-based surface protective film is peeled off from the adherend.

In the method for attaching a polypropylene surface protective film of the present invention, two different types of polypropylene surface protective films are used, the adherend is sandwiched between these adhesive surfaces, and the periphery of the adherend is wrapped around. It is also possible to adopt a form. In this case, said (i) value is peeling strength at the time of peeling at the time of bonding the adhesive surfaces of these two types of polypropylene surface protective films, and said (ii) value is each polypropylene type When the surface protective film and the adherend are bonded, the peel strength at the time of peeling is used. In this case, (i) value is 5 N / 25 mm or more, preferably 6 N / 25 mm or more, and the ratio of (i) value to each (ii) value is 3.0 or more, preferably 3.5 or more. is there.
As a result, the entire surface of the adherend can be completely sealed by sandwiching the surface-protected adherend from both sides and wrapping the surroundings, and the adhesive residue phenomenon from the adhesive layer to the adherend when opened Therefore, it is possible to provide a mounting method capable of protecting the surface of the adherend with high sealing performance, sealing performance, and reliability.

More specifically, the polypropylene-based surface protective film used in the present invention adopts a film configuration form including at least two layers of a base material layer and an adhesive layer as described below.
In this case, the base material layer is made of a resin mainly composed of polypropylene. At that time, the method for producing polypropylene is not particularly limited, and a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst is used. Can be manufactured. The melt flow rate of the polypropylene used in the present invention (MFR (according to JIS K7210, at 230 ° C. under a 2.16 kg load measurement condition)) is usually 0.1 to 50 g / 10 min, preferably 0.5 to 30 g. / 10 minutes, and the density (according to JIS K7112) is usually 895 to 915 kg / m ³ , preferably 897 to 912 kg / m ³ .
In addition, as a composition thereof, either a polypropylene having a homo structure polymerized only with a propylene component, or a so-called random polypropylene or a block polypropylene in which propylene is mainly copolymerized with ethylene or other α-olefin is mainly used. Resin may be used, and resin of any skeleton structure of isotactic structure or syndiotactic structure may be used. By adopting polypropylene as a main component in the base material layer, transparency, low fish eye property, appropriate flexibility, and mechanical strength can be exhibited. Among these, it is more preferable to employ a random polypropylene having an isotactic structure, particularly from the viewpoint of balance of transparency, appropriate flexibility, and film-forming property.

  At that time, the polypropylene resin constituting the base material layer is made of other resin components, specifically, low-density polyethylene, within the range that does not impair the transparency and appropriate flexibility of the target polypropylene surface protective film. A polyolefin resin such as medium-high density polyethylene, polybutene, poly-4-methyl-1-pentene, and ethylene / α-olefin copolymer may be appropriately added to the polypropylene resin. In addition, various additives such as lubricants, antistatic agents, antioxidants, ultraviolet absorbers, weathering agents, colorants, crystal nucleating agents, light-shielding agents, heat-shielding agents, etc. are appropriately added to the polypropylene resin depending on the purpose and application. It can be added and blended.

The adhesive layer is preferably composed of the following propylene / ethylene / α-olefin copolymer (A) mainly composed of propylene and polypropylene (B).
In this case, the propylene / ethylene / α-olefin copolymer (A) has a propylene-derived constitutional unit in an amount of 50 to 90 mol%, preferably 55 to 88 mol%, and an ethylene-derived constitutional unit in an amount of 6 to 23 mol%, preferably 4 to 27 mol%, preferably 5 to 25 mol% of a structural unit derived from an α-olefin having 7 to 20 mol%, 4 to 10 carbon atoms, preferably 4 to 8 carbon atoms (herein, a structural unit derived from propylene) And a total of the structural unit derived from ethylene and the structural unit derived from α-olefin having 4 to 10 carbon atoms is 100% by mole). At this time, in the composition of the propylene-ethylene / α-olefin copolymer (A) in the region where the structural unit derived from propylene is less than 50 mol% or more than 90 mol%, when blended with polypropylene (B), The compatibility is not sufficient, the desired transparency and appropriate viscoelasticity cannot be obtained, and sufficient sealing properties, sealing properties, and reliability cannot be exhibited in protecting the surface of the adherend. Similarly, the composition of the region in which the structural unit derived from ethylene is less than 6 mol% or more than 23 mol%, and the structural unit derived from α-olefin having 4 to 10 carbon atoms is less than 4 mol% or more than 27 mol%. In the composition of the region, when blended with polypropylene (B), the compatibility is not sufficient, the intended transparency and appropriate viscoelasticity cannot be obtained, and sufficient sealing is required for surface protection of the adherend. It cannot exhibit stop, seal and reliability.

  The method for producing the propylene / ethylene / α-olefin copolymer (A) is not particularly limited, and can be produced using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among these, in particular, by using a metallocene-based catalyst, it becomes possible to control each monomer composition distribution and molecular weight distribution more regularly, thereby achieving better compatibility with the blended polypropylene (B). It becomes possible, and when it is adopted as the main resin of the adhesive layer of the polypropylene-based surface protective film, it is possible to exhibit good performance of transparency and anti-glue resistance. The MFR of the propylene / ethylene / α-olefin copolymer (A) (measured under 230 ° C. and 2.16 kg load according to JIS 7210) is usually 0.1 to 50 g / 10 min, preferably If it is 0.5 to 30 g / 10 min and deviates from this range, the compatibility with polypropylene (B) becomes poor, and it is not preferable from the viewpoint of balance such as film forming property and anti-glue resistance.

On the other hand, the polypropylene (B) which is the other resin constituting the adhesive layer is the same resin as the polypropylene constituting the base material layer described above, and the method for producing the polypropylene is not particularly limited. It can be produced using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. The MFR of polypropylene (B) (under the measurement conditions of 230 ° C. and 2.16 kg load according to JIS K7210) is usually 0.1 to 50 g / 10 minutes, preferably 0.5 to 30 g / 10 minutes. When it is out of this range, the compatibility with the propylene / ethylene / α-olefin copolymer (A) becomes poor, and it is not preferable from the viewpoint of balance between film-forming property and adhesive residue resistance. Moreover, the density (conforming to JIS K7112) is usually 895 to 915 kg / m ³ , preferably 897 to 912 kg / m ³ , and when outside this range, a propylene / ethylene / α-olefin copolymer (shown below) It is not preferable from the viewpoint of balance of adhesive residue resistance and moderate peel strength because it is impossible to maintain a balance of a very uniform good compatibility with A). In addition, as a composition thereof, either a polypropylene having a homo structure polymerized only with a propylene component, or a so-called random polypropylene or a block polypropylene in which propylene is mainly copolymerized with ethylene or another α-olefin is mainly used. Resin may be used, and resin of any skeleton structure of isotactic structure or syndiotactic structure may be used. In particular, homopolypropylene having an isotactic structure or random polypropylene having an isotactic structure is good in terms of compatibility with the propylene / ethylene / α-olefin copolymer (A) and appropriate tackiness. In addition, it is also preferable from the viewpoint of the balance of film-forming properties and adhesive residue resistance.

  The blending ratio of the propylene / ethylene / α-olefin copolymer (A) and polypropylene (B) having the above composition and structure constituting the adhesive layer is 98/2 to 70/30, preferably 95/5 to The range is 75/25. By forming a melt-mixed film of both, the propylene / ethylene / α-olefin copolymer (A) (mainly amorphous structure) and polypropylene (B) (mainly crystal structure) are controlled at the nano-unit level. With this, when used as an adhesive layer resin for polypropylene surface protection films, it has excellent transparency, moderate flexibility, moderate adhesion, and anti-glue resistance. Can be expressed.

  Further, at that time, the propylene / ethylene / α having the above composition and structure constituting the adhesive layer within a range that does not impair the transparency, moderate flexibility and moderate tackiness of the target polypropylene surface protective film. Other resin components such as olefin copolymer (A) and polypropylene (B), specifically, low density polyethylene, medium density polyethylene, polybutene, poly-4-methyl-1-pentene, ethylene / α olefin copolymer, etc. A polyolefin resin or a styrene block copolymer resin may be added as appropriate. In addition, various additives such as antistatic agents, antioxidants, ultraviolet absorbers, weathering agents, colorants, crystal nucleating agents, light-shielding agents, and heat-shielding agents are added to the above resin constituting the adhesive layer for their purposes and applications. Depending on the case, it can be added and blended appropriately.

  The polypropylene-based surface protective film of the present invention comprises at least two layers of the above-mentioned base material layer and an adhesive layer, and the thickness thereof is usually 15 to 200 μm, preferably 20 to 150 μm as the base material layer. As a layer, it is 5-100 micrometers normally, Preferably it is 5-50 micrometers. The total thickness of the surface protective film is 20 to 300 μm, preferably 25 to 200 μm. In addition, at that time, as long as the transparency and appropriate flexibility of the target surface protective film are not impaired, if necessary, another surface layer may be provided on the side opposite to the adhesive layer of the base material layer. You may have the structure which provided the resin layer as an outermost layer which made the polyolefin resin which has a function a main part.

  The polypropylene surface protective film of the present invention uses a known melt-extruded multilayer film forming apparatus, specifically, a cast film forming apparatus incorporating a melt-extruded multilayer structure of 2 types, 2 layers, or 3 types and 3 layers. For example, it can be obtained by performing coextrusion film formation at a molding temperature in the range of 200 to 250 ° C. In addition, when forming a polypropylene surface protective film, if necessary, a PET release film that has been subjected to silicone coating treatment or a silicone release treatment release paper may be bonded to the surface called a separator on the adhesive layer side. You can also.

  On the other hand, a conventionally known surface protective film, for example, the above-mentioned 1) base film is an acrylic copolymer that exhibits adhesive performance on one side of a thermoplastic resin film represented by PET, soft PVC, polyolefin resin, and the like. A coating type adhesive film obtained by coating and drying an adhesive component such as a polymer, natural rubber, modified natural rubber, styrene block copolymer, silicone copolymer, etc. by a solution method or an emulsion method, Or 2) a thermoplastic resin and a styrene block copolymer, a silicone copolymer, an ethylene / α-olefin copolymer, an amorphous polypropylene, and an amorphous propylene constituting a base material represented by a polyolefin resin. Copolymers, ethylene / vinyl acetate copolymers, or thermoplastics that form adhesive layers containing these resins and tackifying resins. In what is called a self-adhesive film obtained by laminating a resin by a co-extrusion method, usually the peel strength (ii) at the time of peeling when the adhesive surface and the adherend are bonded is The pressure-sensitive adhesive component and the pressure-sensitive adhesive resin that make up the pressure-sensitive adhesive layer can be designed and modified relatively freely, and can be appropriately adjusted according to the application and purpose. However, the peel strength (i) at the time of peeling when the adhesive surfaces are bonded to each other tends to be an approximate value to the peel strength (ii) at the time of peeling when the adhesive surface and the adherend are bonded. Specifically, the actual condition is that the ratio between the (i) value and the (ii) value is in a range of approximately 0.3 to 2.0.

  For this reason, in the conventional surface protective film, as an attachment form of the adherend to be surface protected, two surface protective films are superposed such that the adhesive surfaces face each other, or one surface of the surface protective film Folding the protective film so that the pressure-sensitive adhesive layers are on the inner surface side, sandwiching the adherend to be surface-protected between them, and bonding with the surface protective film to wrap around the periphery, heat sealing method The importance is placed on the sealing performance, sealing performance, and reliability, and as a result, the peel strength on the adherend tends to increase. Therefore, it becomes a cause of contamination (so-called adhesive residue) due to component transfer from the surface protective film adhesive layer to the adherend surface during peeling.

On the other hand, in the mounting method of the polypropylene-based surface protective film in the present invention, the propylene / ethylene / α-olefin copolymer (A) and the polypropylene (B) having the above composition and structure constituting the adhesive layer; By adopting the proper blending ratio, it is possible to achieve a very uniform and well-matched morphology in which both are controlled at the nano-unit level, and when bonded to an adherend such as a resin body, metal body or ceramic body In addition, it exhibits appropriate adhesive properties. On the other hand, when these pressure-sensitive adhesive surfaces are bonded to each other, both pressure-sensitive adhesive layers of uniform and specific morphologies are formed of both propylene / ethylene / α-olefin copolymer (A) and polypropylene (B). It is considered that the interfaces are intertwined with each other in a complicated manner, and as a result, strong peel strength is developed.
The phenomenon is a known adhesive resin constituting the adhesive layer in the conventional surface protective film, for example, acrylic copolymer, natural rubber, modified natural rubber, styrene block copolymer, silicone copolymer. , Ethylene / α-olefin copolymer, amorphous polypropylene, amorphous propylene copolymer, ethylene / vinyl acetate copolymer, or adhesive resin compositions in which tackifying resins are blended with these resins It is difficult to express.

  By the mounting method of the polypropylene-based surface protective film of the present invention, the peel strength (i) at the time of peeling when the pressure-sensitive adhesive surfaces that could not be achieved are pasted together can be greatly increased. As a result, By adopting a form in which the surface-protected adherend is sandwiched from both sides and wrapped around, it is possible to protect the surface of the adherend with high sealing, sealing and reliability without using a heat sealing method. It is possible to achieve a mounting method for surface protection. Further, there is no concern about the adhesive residue phenomenon from the adhesive layer to the adherend at the time of opening, and surface protection is developed while maintaining proper adhesiveness to the adherend.

  In addition, by utilizing this method for mounting the polypropylene surface protective film of the present invention, as a new field of development, not only for the purpose of preventing scratches on the surface of the adherend, preventing weathering deterioration, and preventing dust adhesion, It can also be used for the purpose of surface protection with high water resistance and moisture resistance. In addition, for example, by depositing a specific metal compound or applying a specific inorganic compound on the surface side of the base material layer of the surface protective film, a gas barrier function can be imparted, and light shielding and heat shielding can be imparted. can do. Moreover, new functions, such as provision of a high degree of rust prevention property, can be added to the adhesion layer resin by, for example, melting and adding a vaporizable rust prevention agent.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.
[Evaluation method]
Optical properties :
Based on JIS K7105, the haze and total light transmittance were measured by irradiating light from the substrate surface side.
Mechanical properties :
The tensile elastic modulus was measured according to JIS K7161.
Peel strength between adhesive surfaces of sample film :
In accordance with JIS Z0237, under the 23 ° C. × 50% RH environmental conditions, the sample films were laminated so that the adhesive surfaces face each other, and left to stand for 1 day. Then, peeling (90 degree peeling) was performed at a tensile speed of 300 mm / min using a tensile test measuring device, and the peel strength (i) value per 25 mm width was measured.
Peel strength against acrylic and stainless steel :
In accordance with JIS Z0237, on acrylic plate (width 50 mm x length 76 mm x thickness 1 mm) and stainless steel plate (SUS304, surface finish BA product number, width 50 mm x length 100 mm x thickness 1 mm) under 23 ° C x 50% RH environmental conditions After the sample film was pasted and allowed to stand for one day, it was peeled off (180 degree peeling) at a tensile rate of 300 mm / min using the tensile test measuring device under the same 23 ° C. × 50% RH environmental conditions. The peel strength (ii) value ((ii) -1: vs. acrylic) and (ii) -2: vs. stainless steel) per 25 mm width was measured. (At that time, visual observation of adhesive residue of the adhesive at the acrylic plate interface and the stainless steel plate interface after peeling was also performed.)

A sample film (width 100 mm x length 150 mm) on a stainless steel plate (SUS304, surface finish BA product number, width 50 mm x length 100 mm x thickness 10 mm) in accordance with JIS Z0237, with stainless steel sandwiched from both the top and bottom surfaces. As shown in FIG. 1, two sample films 4 are bonded so as to be sandwiched from both the upper surface and the lower surface, and bonded and overlapped portions (about 20 mm wide) between the four adhesive surfaces (adhesive layers 3 and 3 ′). ) Was completely sealed so that there was no gap from. Then, it was immersed in the water colored red for 5 minutes, and it confirmed that there was no water penetration. Next, the sample was placed in a cardboard box (vertical 150 mm × width 200 mm × height 100 mm) and subjected to an up and down shaking vibration test (shaking speed: 2 reciprocations / second, total 500 reciprocations). The sample was immersed in red-colored water for 5 minutes to confirm the degree of holding sealing after the vibration test. Further, the sample film was peeled off from the stainless steel plate, and visual observation of the adhesive residue at the stainless steel plate interface was performed.

[Adopted resin]
The method for synthesizing a propylene / ethylene / α-olefin copolymer, which is a resin used in the examples or comparative examples, will be described below.
(Synthesis Example 1: Propylene / ethylene / α-olefin copolymer (A) Production of PEBR-1)
After charging 833 ml of dry hexane, 100 g of 1-butene, and 1.0 mmol of triisobutylaluminum in a 2000 ml polymerization apparatus sufficiently purged with nitrogen, the temperature in the polymerization apparatus was raised to 40 ° C. The pressure in the system was increased to 0.76 MPa with propylene. Next, the pressure in the polymerization apparatus was adjusted to 0.8 MPa with ethylene. Next, 0.001 mmol of dimethylmethylene (3-tert-butyl-5-methylcyclopentadienyl) fluorenylzirconium dichloride was brought into contact with 0.3 mmol of methylaluminoxane (made by Tosoh Finechem) in terms of aluminum. The toluene solution was added to the polymerization apparatus, polymerized for 20 minutes while maintaining the internal pressure at 0.8 MPa with ethylene at an internal temperature of 40 ° C., and then 20 ml of methanol was added to stop the polymerization reaction. After depressurization, the polymer was precipitated from the polymerization solution in 2 L of methanol and dried under vacuum at 130 ° C. for 12 hours to obtain 36.4 g of propylene / ethylene / α-olefin copolymer (A) PEBR-1. It was.

(Synthesis Examples 2 to 5)
The propylene / ethylene / α-olefin copolymer (A) was prepared in the same manner as in Synthesis Example 1 except that the copolymerization ratio of propylene, ethylene and 1-butene was changed as shown in Table 1. A polymer or a propylene / ethylene copolymer was obtained. The composition of the propylene / ethylene / α-olefin copolymer PEBR-1 to 4 or the propylene / ethylene copolymer EPR-1 obtained in Synthesis Examples 1 to 5 is summarized in the table. The results are shown in Table 1. The composition in Table 1 is shown in mol% of each monomer component.

また以下、表２に、実施例または比較例で使用した樹脂の組成についてまとめて示す。なお各樹脂については、表１または表２中の樹脂記号で示すこともある。

Table 2 summarizes the compositions of the resins used in the examples or comparative examples. In addition, about each resin, it may show with the resin symbol in Table 1 or Table 2.

[Sample film production method]
The base layer resin was extruded from a 40 mmφ single screw extruder (L / D = 28) at 230 ° C., and the adhesive layer resin was extruded at 180 ° C. using a 30 mmφ single screw extruder (L / D = 28). Both molten resins are supplied to a multi-manifold T-shaped die (600 mm width) (coextrusion temperature 230 ° C), and the adhesive layer surface side is a cooling roll (with satin specification, The film was wound so as to be in contact with the cooling set temperature (10 ° C.) to prepare a two-layer film having a structure of base material layer / adhesive layer = 65/15 μm. In addition, the PET film having a thickness of 30 μm, which has been subjected to the silicone release coating treatment immediately before the winding device, is rolled out and pasted so that the release treatment surface overlaps the adhesive layer of the previous two-layer film. Specifically, a sample film with a separator was prepared.

表３中の市販フィルムの基材層／粘着層の厚み構成は、市販フィルム−１では７５／１５μｍ、市販フィルム−２では、５０／１５μｍ、市販フィルム−３では８０／１０μｍである。また市販フィルム−１、市販フィルム−２、及び市販フィルム−３共に、フィルム粘着層側に離型処理されたセパレーターが付帯貼合されている。 [Commercial surface protective film]
Table 3 below shows the composition and the like of commercially available films evaluated as comparative examples.

The thickness constitution of the base material layer / adhesion layer of the commercial film in Table 3 is 75/15 μm for the commercial film-1, 50/15 μm for the commercial film-2, and 80/10 μm for the commercial film-3. Moreover, the separator by which the mold release process was carried out to the film adhesion layer side is attached together with the commercial film-1, the commercial film-2, and the commercial film-3.

[Example 1]
A resin for the adhesive layer was prepared by melt-kneading with a twin screw extruder (L / D = 28) at 200 ° C. in a proportion of 80% by weight of PEBR-1 and 20% by weight of PP-1. Next, using PP-1 as the base material layer resin, in combination with the previously prepared adhesive layer resin (PEBR-1 / PP-1 = 80/20 wt%), a T die cast film forming apparatus Sample film-1 having a structure of base material layer / adhesive layer = 65 μm / 15 μm was prepared.

  At this time, the obtained sample film-1 (surface protective film) was used to measure the optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel in a form in which the separator was removed. did. Further, the sample film-1 was sandwiched from both the upper surface and the lower surface of the stainless steel plate as shown in FIG. The results are shown in Table 4.

[Example 2]
In Example 1, the resin for the adhesive layer was changed to a blending composition of PEBR-1 / PP-2 = 85/15% by weight, and sample film-2 (surface protective film) was prepared under the same conditions as in Example 1. The optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were measured in the form in which the separator was removed. Further, the sample film-2 was sandwiched from both the upper surface and the lower surface of the stainless steel plate as shown in FIG. The results are shown in Table 4.

[Example 3]
In Example 2, the thickness configuration of the base material layer / adhesive layer was changed to 120 μm / 20 μm, sample film-3 (surface protective film) was prepared under the same conditions as in Example 2, and the separator was removed. Measurements of optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were carried out. Further, the sample film-3 was sandwiched from both the upper and lower surfaces of the stainless steel plate as shown in FIG. The results are shown in Table 4.

[Example 4]
In Example 1, the resin for the adhesive layer was changed to a blending composition of PEBR-1 / PP-2 = 78/22% by weight, and sample film-4 (surface protective film) was prepared under the same conditions as in Example 1. The optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were measured in the form in which the separator was removed. Further, the sample film-4 was sandwiched from both the upper and lower surfaces of the stainless steel plate as shown in FIG. The results are shown in Table 5.

[Example 5]
In Example 1, the resin for the adhesive layer was changed to a blending composition of PEBR-2 / PP-2 = 90/10% by weight, and sample film-5 (surface protective film) was prepared under the same conditions as in Example 1. The optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were measured in the form in which the separator was removed. Further, the sample film-5 was sandwiched from both the upper and lower surfaces of the stainless steel plate as shown in FIG. The results are shown in Table 5.

[Comparative Example 1]
In Example 1, the resin for the adhesive layer was changed to a blending composition of PEBR-3 / PP-2 = 85/15% by weight, and sample film-6 (surface protective film) was prepared under the same conditions as in Example 1. The optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were measured in the form in which the separator was removed. In addition, the sample film-6 was sandwiched from both the upper and lower surfaces of the stainless steel plate as shown in FIG. The results are shown in Table 5.

[Comparative Example 2]
In Example 1, the resin for the adhesive layer was changed to a blending composition of PEBR-4 / PP-2 = 85/15% by weight, and sample film-7 (surface protective film) was prepared under the same conditions as in Example 1. The optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were measured in the form in which the separator was removed. Further, the sample film-7 was sandwiched from both the upper and lower surfaces of the stainless steel plate as shown in FIG. The results are shown in Table 6.

[Comparative Example 3]
In Example 1, the resin for the adhesive layer was changed to a blending composition of EPR-1 / PP-2 = 85/15% by weight, and sample film-8 (surface protective film) was prepared under the same conditions as in Example 1. The optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel were measured in the form in which the separator was removed. Further, the sample film-8 was sandwiched from both the upper and lower surfaces of the stainless steel plate as shown in FIG. The results are shown in Table 6.

[Reference Example 1]
In Example 1, the sample film-1 (surface protective film) was changed to the commercially available film-1, and measurement of optical properties, mechanical properties, peel strength between adhesive surfaces, and peel strength against acrylic and stainless steel was performed. Moreover, after mounting commercially available film-1 from both the upper surface and lower surface of a stainless steel plate as shown in FIG. The results are shown in Table 7.

[Reference Example 2]
In Example 1, the sample film-1 (surface protective film) was replaced with the commercially available film-2, and optical properties, mechanical properties, peel strength between the adhesive surfaces, and acrylic and stainless steel peel strength were measured. Moreover, after mounting commercially available film-2 from both the upper surface and lower surface of a stainless steel plate as shown in FIG. The results are shown in Table 7.

[Reference Example 3]
In Example 1, the sample film-1 (surface protective film) was replaced with the commercially available film-3, and optical properties, mechanical properties, peel strength between the adhesive surfaces, and acrylic and stainless steel peel strength were measured. Moreover, after mounting commercially available film-3 from both the upper surface and the lower surface of a stainless steel plate as shown in FIG. The results are shown in Table 7.

[Example 6]
In Example 1, regarding the measurement of peel strength between pressure-sensitive adhesive surfaces, the combination of pressure-sensitive adhesive surfaces was changed to a combination of different types of sample film-1 and sample film-5, and bonding was performed to measure the peel strength. did. Similarly, instead of using sample films-1 and sandwiching from both the upper and lower surfaces of the stainless steel plate and sealing the four sides, a combination of sample film-1 (upper surface) and sample film-5 (lower surface) is used. Instead, it was sandwiched from both the upper and lower surfaces of the stainless steel plate, and the four sides were sealed, followed by a mounting seal test. The results are shown in Table 8.

[Comparative Example 4]
In Example 1, regarding the measurement of peel strength between pressure-sensitive adhesive surfaces, the combination of pressure-sensitive adhesive surfaces is changed to a combination between different types of sample film-1 and sample film-8, and bonding is performed to measure the peel strength. did. Similarly, instead of using sample films-1 and sandwiching from both the upper and lower surfaces of the stainless steel plate and sealing the four sides, a combination of sample film-1 (upper surface) and sample film-8 (lower surface) is used. Instead, it was sandwiched from both the upper and lower surfaces of the stainless steel plate, and the four sides were sealed, followed by a mounting seal test. The results are shown in Table 8.

[Comparative Example 5]
In Example 1, regarding the measurement of peel strength between pressure-sensitive adhesive surfaces, the combination of the pressure-sensitive adhesive surfaces was changed to a combination of different types of sample film-1 and commercial film-1, and the peel strength was measured. did. Similarly, instead of using sample films-1 and sandwiching from both the upper and lower surfaces of the stainless steel plate and sealing the four sides, a combination of sample film-1 (upper surface) and commercial film-1 (lower surface) is used. Instead, it was sandwiched from both the upper and lower surfaces of the stainless steel plate, and the four sides were sealed, followed by a mounting seal test. The results are shown in Table 8.

Peeling strength (unit: N / 25 mm) when peeling the adhesive surfaces of the polypropylene surface protective film to each other (i), peeling when peeling the adhesive surface to the adherend When the strength (unit: N / 25 mm) is (ii), (i) the value is 5 N / 25 mm or more, and the ratio of the (i) value to the (ii) value is 3.0 or more. In Examples 1 to 6, the values of the mounting seal test were excellent, none of them penetrated water, the sealing performance and sealing performance were high, and no adhesive residue was observed. Further, in the propylene / ethylene / α-olefin copolymer, the propylene-derived structural unit is 50 to 90 mol%, the ethylene-derived structural unit is 6 to 23 mol%, and the structural unit derived from the α-olefin having 4 to 10 carbon atoms is used. By setting it to 4 to 27 mol% (here, the total of the structural unit derived from propylene, the structural unit derived from ethylene, and the structural unit derived from an α-olefin having 4 to 10 carbon atoms is 100 mol%), The total light transmittance was also good (Examples 1-6). On the other hand, in Comparative Examples 1 and 3 using PEBR-3 and EPR-1 in which the ratio of propylene / ethylene / α-olefin is out of the above range, (i) the value is low and the mounting sealability is insufficient. Furthermore, the optical properties (haze and total light transmittance) were not sufficient.
Moreover, in Comparative Example 2 using PEBR-4 in which the ratio of propylene / ethylene / α-olefin was outside the above range, the ratio of the (i) value to the (ii) value was small, and adhesive residue was generated.
Furthermore, when using a commercially available film, both (i) value and (ii) value are equivalent, or (ii) value is higher than (i) value, and (i) value is low The adhesive sealability was inferior, and (ii) when the value was too high, adhesive residue was generated.
Further, even when two different polypropylene surface protective films were used, the mounting sealability was insufficient in Comparative Example 4 and Comparative Example 5 where (i) the value was low.

  The method for mounting the surface protective film of the present invention has a very high adhesive force between the adhesive surfaces as compared to the adhesion to the adherend, and has excellent transparency, environmental compatibility, and moderate flexibility. Use a packaging form that requires a large specific device for sealing, such as vacuum packaging or heat-sealing packaging, by wrapping the surroundings with an adherend to be protected by a film. There is no. In addition, by adopting a surface protective film having certain adhesive properties, the entire adherend is completely sealed, and there is no concern about the adhesive residue phenomenon from the adhesive layer to the adherend when opened, Makes it possible to protect the surface of adherends with high sealing, sealing and reliability. As a result, the mounting method can be developed into a new field, not only for the purpose of preventing scratches on the surface of the adherend, preventing weathering deterioration, and preventing dust adhesion, but also providing high water resistance and moisture resistant surface protection. It can also be used for purposes, and its industrial use value is extremely high as a surface protection film in a wide range of applications such as optical materials, automobile parts materials, building parts materials, daily necessities materials, semiconductor parts materials.

DESCRIPTION OF SYMBOLS 1 Adhering body 2, 2 'Base material layer 3, 3' Adhesive layer 4, 4 'Surface protection film

Claims (2)

The mounting form of the adherend whose surface is protected by the bonding of the surface protective film is
Two polypropylene-based surface protective films are stacked so that the adhesive surfaces face each other, or one polypropylene-based surface protective film is folded so that the adhesive surfaces are on the inner surface side. It is a mounting method of a polypropylene surface protection film that sandwiches the adherend to be surface protected between the two, and adheres the adhesive surfaces of the polypropylene surface protection film to wrap around the periphery of the adherend,
Peel strength (unit: N / 25 mm) at the time of peeling when the adhesive surfaces of the polypropylene surface protective film are bonded to each other (i), at the time of peeling when the adhesive surface and the adherend are bonded When the peel strength (unit: N / 25 mm) of (ii) is (ii), (i) the value is 5 N / 25 mm or more, and the ratio of the (i) value to the (ii) value is 3.0 or more. A method of wearing a polypropylene surface protective film. In Claim 1, the structure of the said polypropylene-type surface protection film consists of at least 2 layers of a base material layer and an adhesion layer, the said base material layer consists of resin which has a polypropylene as a main component, and the said adhesion layer originates in propylene. 50 to 90 mol% of structural units, 6 to 23 mol% of structural units derived from ethylene, and 4 to 27 mol% of structural units derived from α-olefins having 4 to 10 carbon atoms (where propylene derived structural units and ethylene From the resin of propylene / ethylene / α-olefin copolymer (A) and polypropylene (B) containing (the total of the structural unit derived from α-olefin having 4 to 10 carbon atoms is 100 mol%) And the blending ratio of the propylene / ethylene / α-olefin copolymer (A) and the polypropylene (B) is in the range of 98/2 to 70/30% by weight. Mounting method of a polypropylene-based surface protective film.

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