Protective film and laminate

Abstract

To provide a new protective film.SOLUTION: There is provided a protective film which has a film substrate and an adhesive layer formed on at least one surface of the film substrate, wherein the adhesive layer has grooves on a surface opposite to the film substrate and the width of the grooves is 30 μm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to protective films and laminates. [Background technology]

[0002] Polycarbonate is a thermoplastic plastic that has excellent transparency, impact resistance, heat resistance, flame retardancy, dimensional stability, etc., and is used in various fields such as transportation equipment, miscellaneous goods, etc. However, when polycarbonate is used alone, there is a possibility that it may crack and shatter, so from the viewpoint of shatter prevention, a protective film has been attached to the surface.

[0003] When a PET film is attached to polycarbonate, outgassing from the polycarbonate can cause the film to float.

[0004] Incidentally, Patent Document 1 discloses a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a thickness of 150 μm or more and 5000 μm or less, the pressure-sensitive adhesive layer containing a vinyl polymer (A) and an acrylic adhesive polymer (B), the vinyl polymer (A) containing a structural unit derived from an alicyclic vinyl monomer, having a glass transition temperature of 90° C. or more and 200° C. or less and a number average molecular weight of 1,000 or more and 10,000 or less, a second Tg which is a glass transition temperature calculated from a surface layer portion of the pressure-sensitive adhesive layer obtained by X-ray photoelectron spectroscopy analysis of the pressure-sensitive adhesive layer is 80° C. or more higher than a first Tg which is the glass transition temperature of the entire pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer has a gel fraction based on the acrylic adhesive polymer (B) of 80% or more. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-029725 Summary of the Invention [Problem to be solved by the invention]

[0006] It is described that the pressure-sensitive adhesive sheet disclosed in Patent Document 1 can suppress the growth of outgassing from the adherend in the film thickness direction and suppress foaming. According to the study by the present inventors, there are only a limited number of pressure-sensitive adhesives and film substrates that can be used as protective films capable of preventing film lifting due to outgassing, and improvements have been required. The present disclosure aims to provide a new protective film. [Means for solving the problem]

[0007] The present inventors conducted intensive research to solve the above problems and discovered that by providing a groove portion having a specific width in the adhesive layer, it is possible to suppress film lifting due to outgassing, which led to the present disclosure.

[0008] An example aspect of this embodiment is described as follows.

[0009] (1) A pressure-sensitive adhesive sheet comprising a film substrate and a pressure-sensitive adhesive layer formed on at least one surface of the film substrate; the pressure-sensitive adhesive layer has a groove on a surface facing away from the film substrate, A protective film, wherein the groove has a width of 30 μm or more. (2) The water vapor permeability coefficient of the film substrate at a temperature of 0° C. and a pressure of 101.325 kPa is 4500×10 -10 cm 3 mm / cm 2 The protective film according to (1), wherein the resistance to heat is 0.001 s cmHg or less. (3) The protective film according to (1) or (2), wherein the film substrate contains at least one polymer selected from the group consisting of polyvinyl chloride, polyethylene terephthalate, polyethylene, polyvinylidene chloride, and polypropylene. (4) A laminate comprising the protective film according to any one of (1) to (3) and a polycarbonate substrate, A laminate in which a protective film is attached to a polycarbonate substrate via an adhesive layer of the protective film. Effect of the Invention

[0010] The present disclosure makes it possible to provide a protective film capable of suppressing film lift-up due to outgassing, and a laminate including a protective film and a polycarbonate substrate. [Brief description of the drawings]

[0011] [Figure 1] A schematic diagram of a process for obtaining a laminate 200 from a protective film 100 and a polycarbonate substrate 9 is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The protective film and laminate of this embodiment will be described in detail below. One aspect of this embodiment is a protective film comprising a film substrate and a pressure-sensitive adhesive layer formed on at least one surface of the film substrate, the pressure-sensitive adhesive layer having a groove on the surface facing the film substrate, and the width of the groove is 30 μm or more. Another aspect of this embodiment is a laminate including the protective film and a polycarbonate substrate, in which the protective film is attached to the polycarbonate substrate via the pressure-sensitive adhesive layer of the protective film.

[0013] (Film substrate) The film substrate is not particularly limited as long as it is a film used to protect a polycarbonate substrate or the like.

[0014] Conventional protective films are limited in the types and thicknesses of films that can be used because films with low gas permeability tend to float due to outgassing. On the other hand, the protective film of the present invention can suppress film floating due to outgassing regardless of the type of film substrate by providing a groove in the adhesive layer. Therefore, the film substrate may be a film made of a material with low gas permeability that has been difficult to use in the past.

[0015] The water vapor transmission coefficient of the film substrate at a temperature of 0°C and a pressure of 101.325 kPa is 140000 x 10 -10 cm 3 mm / cm 2 In one preferred embodiment, the protective film of the present disclosure has a water vapor permeability of 6500×10 or less. -10 cm 3 mm / cm 2 s cmHg or less, 4500×10 -10 cm 3 mm / cm 2 The lower limit of the water vapor permeability coefficient is not particularly limited, but may be, for example, 14×10 -10 cm 3 mm / cm 2 s cmHg or more, 120×10 -10 cm 3 mm / cm 2 The water vapor transmission coefficient can be measured in accordance with JIS K 7129 at a temperature of 0°C, a pressure of 101.325 kPa, and with water vapor as the gas type. The water vapor transmission coefficient is also called the moisture permeability coefficient.

[0016] The film substrate is not particularly limited in terms of its material, but examples thereof include polyvinyl alcohol (e.g., 84500×10 -10 cm 3 mm / cm 2 ·s·cmHg), polyurethane (e.g., 64300×10 -10 cm 3 mm / cm 2 ·s·cmHg), cellulose acetate (e.g., 60500×10 -10 cm 3 mm / cm 2 ·s·cmHg), polystyrene (e.g., 10000×10 -10 cm 3 mm / cm 2 ·s·cmHg), polycarbonate (e.g., 7000×10 -10 cm 3mm / cm 2 ·s·cmHg), polyvinyl chloride (e.g., 4500×10 -10 cm 3 mm / cm 2 ·s·cmHg), polyethylene terephthalate (e.g., 1800×10 -10 cm 3 mm / cm 2 ·s·cmHg), polyethylene (e.g., 1100×10 -10 cm 3 mm / cm 2 ·s·cmHg), polyvinylidene chloride (e.g., 500×10 -10 cm 3 mm / cm 2 ·s·cmHg), polypropylene (e.g., 700×10 -10 cm 3 mm / cm 2 The film substrate may contain at least one polymer having a low water vapor permeability coefficient selected from polyvinyl chloride, polyethylene terephthalate, polyethylene, polyvinylidene chloride, and polypropylene.

[0017] The thickness of the film substrate is not particularly limited, but may be, for example, 15 to 500 μm, or may be 50 to 300 μm. The shape of the film substrate is not particularly limited and may be appropriately set depending on the shape of the material to be protected by the protective film.

[0018] (Adhesive layer) The adhesive layer is not particularly limited as long as it can adhere or bond to the object to be protected such as a polycarbonate substrate and the film substrate. The adhesive layer may have a groove on the surface facing the film substrate, in other words, on the surface, and the width of the groove may be 30 μm or more.

[0019] The width of the groove is preferably 40 μm or more. There is no particular upper limit to the width of the groove, but it is usually 60 μm or less, and preferably 50 μm or less. There is no particular limit to the proportion of the groove in the adhesive layer, but the area of ​​the groove per unit area may be 15 to 45%, or may be 25 to 35%.

[0020] The shape of the grooves is not particularly limited, and may be linear, curved, lattice-like, or a combination thereof. In the protective film of this embodiment, outgas is discharged to the outside through the grooves, and it is therefore believed possible to suppress lifting of the film due to outgassing. For this reason, it is preferable that the grooves are connected to the ends of the film. In addition, the arrangement of the grooves is not particularly limited, but the area of ​​the adhesive portion surrounded by the grooves or the adhesive portion surrounded by the grooves and the ends is, for example, 50 to 1,000,000 μm 2 More preferably, it is 500 to 850,000 μm 2 It is.

[0021] The adhesive layer may be an acrylic adhesive, a rubber adhesive, a polyurethane adhesive, a silicone adhesive, an epoxy adhesive, or the like, or may be any other resin adhesive.

[0022] The thickness of the adhesive layer is not particularly limited, but the thickness of the portion other than the groove is, for example, 40 to 100 μm, preferably 40 to 60 μm, and the depth of the groove is, for example, 20 to 40 μm, preferably 25 to 30 μm.

[0023] (Protective film) The protective film of the present embodiment includes the film substrate and the pressure-sensitive adhesive layer formed on at least one surface of the film substrate. The film substrate and the pressure-sensitive adhesive layer may be in direct contact with each other, or may have another layer therebetween. In one embodiment, the pressure-sensitive adhesive layer is formed on one surface of the film substrate.

[0024] There is no particular restriction on the method for producing the protective film. For example, the raw material of the film substrate, such as a resin composition, can be molded by a molding method such as extrusion molding, casting molding, or calendar molding to obtain a film substrate. In addition, a laminated film having a film substrate and an adhesive layer can be obtained by applying an adhesive to the film substrate by a coating method such as roll coating, gravure coating, die coating, or calendar coating. Then, a protective film of this embodiment can be obtained by providing a groove in the adhesive layer. In addition to the method of directly applying the adhesive to the film substrate, the adhesive can be applied to a release film to form an adhesive layer, and the adhesive layer can be laminated to the film substrate to obtain a laminated film having a film substrate and an adhesive layer. There is no particular restriction on the method for providing a groove in the adhesive layer, but for example, a release film having a ridge corresponding to the groove may be prepared, and the release film may be pressed against the adhesive layer before the groove is provided, to provide a groove in the adhesive layer. In addition, the adhesive may be applied to a release film having a ridge corresponding to the groove to obtain an adhesive layer having a groove. As another method for providing the grooves in the adhesive layer, the adhesive layer may be etched using a conventional method, for example, to provide the grooves.

[0025] (Polycarbonate base material) The object to be protected by the protective film of the present embodiment is not particularly limited, but may be, for example, a polycarbonate substrate. It is known that the polycarbonate substrate generates outgassing, and by using the protective film, it is possible to significantly suppress floating due to outgassing, compared to the case where other protective films are used. The shape and thickness of the polycarbonate substrate are not particularly limited, and are appropriately selected depending on the application of the polycarbonate substrate.

[0026] (Laminate) The laminate of the present embodiment includes the protective film and the polycarbonate substrate, and the protective film is attached to the polycarbonate substrate via an adhesive layer of the protective film. A schematic diagram of a process for obtaining a laminate 200 from a protective film 100 and a polycarbonate substrate 9 is shown in FIG.

[0027] In FIG. 1, a protective film 100 having a film substrate 1 and an adhesive layer 3 is attached to a polycarbonate substrate 9 to obtain a laminate 200. The adhesive layer 3 of the protective film 100 has a plurality of grooves 5, each of which has a width 7 of 30 μm or more. The polycarbonate substrate 9 usually contains outgas 11, which is gradually released from the polycarbonate substrate 9 to the outside. Since the adhesive layer 3 of the laminate 200 has the grooves 5, the outgas 11 can be released to the outside, and lifting of the film is suppressed.

[0028] There is no particular restriction on the method for producing the laminate, and the conditions for attachment can be appropriately selected depending on the material of the adhesive layer, etc. Usually, attachment is performed under conditions in which the grooves of the adhesive layer are maintained in the laminate. There is no particular restriction on the conditions for attachment, and for example, attachment can be performed under an attachment load of 0.5 kgf to 8 kgf and an attachment temperature of 5°C to 40°C. If necessary, a post-heating step can be provided. The post-heating step can be performed, for example, by setting the temperature of the heater to 90°C to 100°C, and continuing heating for 0 seconds to 2 minutes after the film surface temperature reaches the set temperature. EXAMPLES

[0029] The present embodiment will be described below with reference to examples, but the present disclosure is not limited to these examples.

[0030] [Reference example 1] Polyurethane (water vapor permeability coefficient: 64300 x 10 -10 cm 3 mm / cm 2A 1524 mm × 15.2 m × 150 μm film substrate was obtained by casting.

[0031] The acrylic adhesive was applied to the film substrate by roll coating to obtain a protective film having a film substrate and an adhesive layer.

[0032] The protective film was laminated so that the adhesive layer side and the polycarbonate substrate were in contact with each other, and the two were attached with an attachment load of 4 kgf and an attachment temperature of 23° C. to obtain a laminate.

[0033] [Example 1] Polyvinyl chloride (water vapor permeability coefficient: 4500 x 10 -10 cm 3 mm / cm 2 The resulting film substrate was 1,372 mm × 50 m × 50 μm in size.

[0034] An acrylic adhesive was applied by roll coating to a release film having randomly arranged ridges to form an adhesive layer on the release film.

[0035] The adhesive layer is overlaid on the film substrate and laminated with a laminator to form a film substrate and an adhesive layer, and the adhesive layer has a groove (width 40 μm, ratio of grooves per unit area 30%, area of ​​adhesive portion surrounded by the grooves 500 to 850,000 μm). 2 ) was obtained as a protective film.

[0036] The protective film was laminated so that the adhesive layer side was in contact with the polycarbonate substrate, and the laminate was attached at a bonding load of 4 kgf and a bonding temperature of 23° C. In the laminate, the adhesive layer side of the protective film was laminated so that the adhesive layer side was in contact with the transparent glass substrate, and the laminate was attached at a bonding load of 4 kgf and a bonding temperature of 23° C., and it was confirmed that the grooves of the adhesive layer remained in the laminate by observing the back side of the glass substrate with a microscope.

[0037] [Comparative Example 1] Polyvinyl chloride was extruded to obtain a film substrate having dimensions of 1372 mm×50 m×50 μm.

[0038] An acrylic adhesive was applied by roll coating to a release film having ridges arranged in a lattice pattern to form an adhesive layer on the release film.

[0039] The adhesive layer is placed on the film substrate and laminated with a laminator to form a film substrate and an adhesive layer, and the adhesive layer has a groove (width 15 μm, ratio of grooves per unit area 6%, adhesive area surrounded by the grooves is 140,000 μm). 2 ) was obtained as a protective film.

[0040] The protective film was laminated so that the adhesive layer side and the polycarbonate substrate were in contact with each other, and the two were attached with an attachment load of 4 kgf and an attachment temperature of 23° C. to obtain a laminate.

[0041] [Comparative Example 2] Polyethylene terephthalate (water vapor permeability coefficient: 1800 x 10 -10 cm 3 mm / cm 2 The resulting film substrate was 914 mm × 30 m × 100 μm in size.

[0042] The acrylic adhesive was applied to the film substrate by roll coating to obtain a protective film having a film substrate and an adhesive layer.

[0043] The protective film was laminated so that the adhesive layer side and the polycarbonate substrate were in contact with each other, and the two were attached with an attachment load of 4 kgf and an attachment temperature of 23° C. to obtain a laminate.

[0044] [Film floating evaluation] The laminates obtained in the Reference Example, the Examples, and the Comparative Examples were subjected to aging treatment by keeping them at 80° C. for 24 hours, and visually observed whether lifting of the protective film occurred. No lifting occurred in the laminates of Reference Example 1 and Example 1, but lifting was observed in the laminates of Comparative Example 1 and Comparative Example 2.

[0045] The upper limit and / or lower limit of the numerical ranges described in this specification can be arbitrarily combined to define a preferred range. For example, the upper limit and lower limit of the numerical range can be arbitrarily combined to define a preferred range, the upper limit of the numerical range can be arbitrarily combined to define a preferred range, and the lower limit of the numerical range can be arbitrarily combined to define a preferred range.

[0046] Although the present embodiment has been described in detail above, the specific configuration is not limited to this embodiment, and even if there are design changes within the scope that does not deviate from the gist of this disclosure, they are included in this disclosure. [Explanation of symbols]

[0047] 1 Film substrate 3 Adhesive layer 5 Groove 7 Groove width 9 Polycarbonate substrate 11 Outgassing 100 Protective Film 200 Laminate

Claims

1. The adhesive tape comprises a film substrate and a pressure-sensitive adhesive layer formed on at least one surface of the film substrate, the pressure-sensitive adhesive layer has a groove on a surface facing away from the film substrate, A protective film, wherein the groove has a width of 30 μm or more.

2. The water vapor permeability coefficient of the film substrate at a temperature of 0° C. and a pressure of 101.325 kPa is 4500×10 －１０ cm ３ mm / cm ２ The protective film according to claim 1 , having a compressive strength of 0.5 s·cmHg or less.

3. The protective film according to claim 1 , wherein the film substrate comprises at least one polymer selected from the group consisting of polyvinyl chloride, polyethylene terephthalate, polyethylene, polyvinylidene chloride, and polypropylene.

4. A laminate comprising the protective film according to claim 1 and a polycarbonate substrate, A laminate in which a protective film is attached to a polycarbonate substrate via an adhesive layer of the protective film.

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