Adhesive layer for laser-processed film and laser-processed film

Abstract

The objective is to provide an adhesive layer for laser-processed films that does not peel off due to gas jetting during laser processing and has excellent peelability from the metal plate after laser processing. [Solution] An adhesive layer for laser-processed films, comprising 0.90 to 0.96 g / cm³ 3 An evaluation film is provided on a polyethylene substrate having a density and a thickness of 90 μm, on which an adhesive layer for laser-processed films is provided. When this evaluation film is attached to a stainless steel plate and the evaluation film is peeled off the stainless steel plate, the adhesive layer for laser-processed films exhibits an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min.

Description

Technical Field

[0001] The present invention relates to an adhesive layer for a laser processing film and a laser processing film.

Background Art

[0002] Conventionally, a method has been used in which a laser processing film is attached to a metal plate and the metal plate is processed by irradiating the laser through the laser processing film. In this processing method, the metal plate is cut while melting the metal plate with a laser. The laser processing film is used for the purpose of preventing damage during handling at that time, subsequent press processing, and even transportation of the processed metal parts.

[0003] Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2021-187908) discloses a surface protection film including a base material layer and an adhesive layer provided on at least one surface of the base material layer, wherein the base material layer contains a resin and carbon black, and the average particle diameter of the carbon black is in the range of 20 to 50 nm. Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2013-018964) discloses an adhesive film including a resin film as a base material and an adhesive layer provided on at least one surface of the resin film, wherein the base material has a laser light absorption rate of 20% or more in the wavelength range of 1000 nm to 1100 nm, and the base material includes a laser light absorption layer made of a resin composition containing carbon black as a laser light absorber for increasing the laser light absorption rate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document Z

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in the laser processing method for metal plates, compressed air, oxygen, nitrogen, or other gases are injected at high pressure into the laser irradiation area of ​​the metal plate to prevent the molten metal from reattaching to the metal plate. During this high-pressure gas injection, the pressure of the gas injection makes it easier to peel the laser-processed film from the metal plate. For this reason, conventional laser-processed films with strong adhesion to the metal plate were used. However, such laser-processed films had the problem of being difficult to peel off the laser-processed film from the metal plate after laser processing. As described above, with conventional laser-processed films, it was difficult to achieve both good adhesion to the metal plate during laser processing (gas injection) and easy peeling from the metal plate after laser processing.

[0006] In view of the limitations of the prior art described above, the present invention aims to provide an adhesive layer for laser-processed films that does not peel off due to gas jetting during laser processing and has excellent peelability from metal plates after laser processing. The inventors of the present invention have discovered that by using an adhesive layer for laser-processed films in which the adhesive force at a specific peeling speed is within a specific range in an evaluation film, it is possible to achieve both good adhesion to the metal plate during laser processing (gas injection) and good peelability from the metal plate after laser processing, and have completed the present invention. [Means for solving the problem]

[0007] In other words, the present invention and its various embodiments are as follows [1] to [5]. However, the present invention is not limited to the following. [1] An adhesive layer for laser-processed films, 0.90~0.96 g / cm³ 3An evaluation film having the adhesive layer for laser-processed films provided on a polyethylene substrate having a density and a thickness of 90 μm is attached to a stainless steel plate, and when the evaluation film is peeled off the stainless steel plate, the adhesive layer for laser-processed films has an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min. [2] The adhesive layer for laser-processed films described in [1] above, wherein when the evaluation film is peeled off the stainless steel plate, it has an adhesive strength of 3.5 to 7.0 N / 25 mm at a peeling speed of 0.3 m / min. [3] The adhesive layer for laser-processed films according to [1] or [2] above, wherein when the evaluation film is peeled off the stainless steel plate, it has an adhesive strength of 0.7 to 2.0 N / 25 mm at a peeling speed of 0.003 m / min. [4] Light-absorbing substrate and On the light-absorbing substrate, an adhesive layer for laser-processed films according to [1] or [2] above is provided. A laser-processed film having the following properties. [5] The laser-processed film according to [4] above, wherein the light-absorbing substrate contains carbon black. [Effects of the Invention]

[0008] According to the present invention, an adhesive layer for laser-processed films can be provided that does not peel off due to gas jetting during laser processing and has excellent peelability from the metal plate after laser processing. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing a laser-processed film according to one embodiment. [Figure 2] This is a schematic plan view of the stainless steel plate that was laser-processed in Examples 1 to 4. [Modes for carrying out the invention]

[0010] <Adhesive layer for laser-processed films> The adhesive layer for laser-processed films of the present invention has a concentration of 0.90 to 0.96 g / cm³. 3 An evaluation film, on which an adhesive layer for laser-processed films is provided on a polyethylene substrate having a density and a thickness of 90 μm, is attached to a stainless steel plate. When the evaluation film is peeled off the stainless steel plate, it exhibits an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min. In this adhesion force measurement test using the evaluation film, the adhesive layer for laser-processed films of the present invention exhibits an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min. This prevents peeling due to gas jets during laser processing and provides excellent peelability from the metal plate after laser processing. In other words, the adhesive layer for laser-processed films has a specific dynamic viscoelasticity that exhibits adhesive forces within a specific range at peeling speeds of 0.003 m / min and 0.03 m / min. Therefore, the laser-processed film has good adhesion to the metal plate against the gas jet during laser processing, and can adhere effectively to the metal plate. As a result, it is possible to prevent the laser-processed film from peeling off the metal plate due to the gas jet during laser processing. Furthermore, when peeling the laser-processed film from the metal plate after laser processing, the adhesive force of the laser-processed film to the metal plate is low, and the laser-processed film can be given excellent peelability.

[0011] The following describes in detail the measurement test of adhesive strength using the evaluation film in the present invention. (1) First, prepare an evaluation film to be used for measuring adhesive strength. The evaluation film should have an adhesive strength of 0.90-0.96 g / cm². 3 It consists of a polyethylene substrate having a density of 0.90 to 0.96 g / cm³ and a thickness of 90 μm, and an adhesive layer for laser-processed films provided on the polyethylene substrate. 3 There are no particular limitations as long as it is a specific (one) density within the range of 0.90~0.96 g / cm³. 3Within this range, it has been confirmed in advance that the adhesive strength does not change depending on the density of the polyethylene substrate. For example, 0.90~0.96 g / cm³ 3 An evaluation film was prepared by applying an adhesive solution to a substrate of low-density polyethylene (LDPE) film (manufactured by Tamapoly Co., Ltd., product name: M-6, thickness 90 μm) having a specific density within a given range, and then drying the solvent of the adhesive to form an adhesive layer for laser-processed films with a thickness of 5 to 12 μm.

[0012] (2) A stainless steel 304HL finished plate (JIS G4305 2021 standard; stainless steel plate) measuring 50 mm in width, 200 mm in length, and 0.6 mm in thickness was prepared. The surface of the stainless steel finished plate was then degreased with ethanol and dried to be used as the substrate. Under an atmosphere of 23°C and 50% RH, the evaluation film was cut to a length of 100 mm and a width of 25 mm, and temporarily attached to the surface of the finished stainless steel plate using a hand roller so that the adhesive layer for the laser-processed film was in contact with it. After this, a pressure roller was used to apply a load of 10 kg from the polyethylene base film side at a speed of 2 m / min to press the evaluation film onto the stainless steel plate, and it was left for 24 hours. Next, using a tensile testing machine (ORIENTEC RTA-1210A), one end of the evaluation film was held, and the evaluation film was peeled from the surface of the stainless steel 304HL finished plate at a peeling angle of 180 degrees and peeling speeds of 0.003 m / min, 0.03 m / min, or 0.3 m / min. The strength (N / 25mm) measured at that time was defined as the adhesive strength. The adhesive strength measurement test will be described in detail in the examples section.

[0013] In the measurement of adhesion using an evaluation film, it is preferably to have an adhesion of 0.7 to 2.0 N / 25 mm at a peeling speed of 0.003 m / min, more preferably to have an adhesion of 0.7 to 1.6 N / 25 mm, and even more preferably to have an adhesion of 0.7 to 1.2 N / 25 mm. In the measurement of adhesion using an evaluation film, it is preferably to have an adhesion of 2.0 to 3.5 N / 25 mm at a peeling speed of 0.03 m / min, more preferably to have an adhesion of 2.0 to 3.0 N / 25 mm, and even more preferably to have an adhesion of 2.0 to 2.6 N / 25 mm. Also, in the evaluation film, as the adhesion at the peeling speeds of 0.003 m / min and 0.03 m / min, a specific adhesion can be selected from within the numerical ranges shown above. Thereby, the adhesive layer for the laser processing film can have suitable dynamic viscoelasticity. As a result, it is possible to prevent the laser processing film from peeling off from the metal plate during gas injection at the time of laser processing, and the laser processing film can have excellent peelability when peeling the laser processing film from the metal plate after laser processing.

[0014] Also, by controlling the type and content ratio of each monomer in the resin constituting the adhesive layer for the laser processing film, the crosslinking degree of the resin, the type and blending ratio of the crosslinking agent, and the film thickness of the adhesive layer for the laser processing film, it is possible to have an adhesion of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesion of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min in the adhesion measurement test using the evaluation film. For example, reducing the film thickness of the adhesive layer for the laser processing film can reduce the adhesion, and increasing the crosslinking degree of the resin constituting the adhesive layer for the laser processing film can reduce the adhesion.

[0015] In the measurement test of the adhesive force of the above (1) and (2) using the evaluation film, when peeling the evaluation film from the surface of the stainless steel 304HL finished plate, it preferably has an adhesive force of 3.5 to 7.0 N / 25 mm at a higher peeling speed of 0.3 m / min, more preferably has an adhesive force of 3.5 to 6.4 N / 25 mm, still more preferably has an adhesive force of 3.5 to 5.8 N / 25 mm, and particularly preferably has an adhesive force of 3.5 to 5.2 N / 25 mm.

[0016] The adhesive layer for the laser processing film contains components such that the evaluation film has an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min. As such components, the adhesive layer for the laser processing film includes, for example, a polymer composed of at least one monomer selected from methacrylic acid, acrylic acid, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, acrylonitrile, 2-hydroxyethyl methacrylate, acrylamide, N-methylol acrylamide, divinylbenzene, and polytetramethylene glycol diacrylate. The polymer can be obtained, for example, by subjecting a solution containing the above monomers, a surfactant, a polymerization initiator, a chain transfer agent, and a solvent to emulsion polymerization of the monomers. In one example, by using a polymer containing a predetermined content of an acrylate monomer and a methacrylate monomer, an adhesive layer for a laser processing film can be obtained that has an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min for the evaluation film.

[0017] The surfactants are not particularly limited, but examples include alkyl sulfate esters, alkylbenzene sulfonates, dialkyl succinate sulfonates, alkyl diphenyl ether disulfonates, polyoxyethylene alkyl ether sulfates, and polyoxyethylene alkylphenyl ether sulfates. More specifically, examples include sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl ether sulfate, sodium lauryl sulfate, sodium alkyl diphenyl ether disulfonate, and ammonium=4-nonyl-2-(1-propenyl)phenoxypoly(n=0~29)ethoxyethyl sulfate.

[0018] The polymerization initiator is not particularly limited, but may include t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyoctanoate, t-butyl peroxyneodecanate, t-butyl peroxyisobutyrate, t-amyl peroxypivalate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicumyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, potassium peroxydisulfate or ammonium peroxydisulfate, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-cyano-2-butane), 2,2'-azobis(methylisobutyrate), 4,4'-azobis(4-cyanopentanoic acid), 4,4'-azobis(4-cyanovaleric acid), 4,4'-azobis(4-cyanopentane-1- Examples include 1,1'-azobis(cyclohexanecarbonitrine), 2,2'-azobis(N,N'-dimethylene isobutylamidine) hydrochloride, 2,2'-azobis(2-amidinopropane) hydrochloride, 2,2'-azobis(N,N'-dimethylene isobutylamine), 2,2'-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide), 2,2'-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobis(isobutylamide) hydrate, 2,2'-azobis(2,2,4-trimethylpentane), or 2,2'-azobis(2-methylpropane).

[0019] The chain transfer agent is not particularly limited, but examples include mercaptans such as t-dodecanethiol, lauryl mercaptan, glycidyl mercaptan, 2-mercaptoethanol, mercaptoacetic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol, as well as α-methylstyrene dimer.

[0020] The solvent is not particularly limited, but examples include water, alcohols such as ethanol, methanol, and isopropanol, ketones such as acetone and methyl ethyl ketone, and ethers such as dioxane and tetrahydrofuran.

[0021] <Laser-processed film> The laser-processed film of the present invention comprises a light-absorbing substrate and an adhesive layer for laser-processed films on the light-absorbing substrate. The light-absorbing substrate is not particularly limited as long as it can absorb at least a portion of the incident light. Examples of resins constituting the light-absorbing substrate include one or more selected from polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6, nylon-66, and polymetaxylene adipamide; polyacrylate; polymethacrylate; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; polysulfone; polyethersulfone; and polyphenylene ether. Among these, one or more selected from polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyimide are preferred, with polyethylene being more preferred, from the viewpoint of having an excellent balance of heat resistance, transparency, mechanical strength, and price. The light-absorbing substrate may also contain a light-absorbing material, such as carbon black. The light-absorbing substrate is preferably composed of a polyolefin containing carbon black, and more preferably of polyethylene containing carbon black. The light-absorbing substrate may further contain additives such as light stabilizers, ultraviolet absorbers, antioxidants, fillers, lubricants, and dispersants as needed.

[0022] The thickness of the light-absorbing substrate is preferably 20 to 300 μm, more preferably 30 to 200 μm, and even more preferably 40 to 150 μm. The thickness of the adhesive layer for the laser-processed film is preferably 1 to 50 μm, more preferably 2 to 20 μm, and even more preferably 3 to 10 μm. The overall thickness of the laser-processed film is preferably 20 to 400 μm, more preferably 30 to 350 μm, and even more preferably 40 to 200 μm.

[0023] Figure 1 is a schematic cross-sectional view of a laser-processed film according to one embodiment. The laser-processed film 1 has a light-absorbing substrate 2 and an adhesive layer 3 for laser-processed films provided on one surface of the light-absorbing substrate 2. The laser-processed film 1 may consist of the light-absorbing substrate 2 and the adhesive layer 3 for laser-processed films as shown in Figure 1, or it may have other layers in addition to the light-absorbing substrate 2 and the adhesive layer 3 for laser-processed films. As a layer other than the light-absorbing substrate 2 and the adhesive layer 3 for laser-processed films, there may be a primer layer disposed between the light-absorbing substrate 2 and the adhesive layer 3 for laser-processed films. By forming a primer layer, the light-absorbing substrate 2 and the adhesive layer 3 for laser-processed films can be bonded well.

[0024] <Method for manufacturing laser-processed film> The method for manufacturing a laser-processed film of the present invention is not particularly limited, as long as it yields an adhesive layer for laser-processed films that, when an evaluation film is attached to a stainless steel plate and the evaluation film is peeled off the stainless steel plate, has an adhesive strength of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive strength of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min. For example, an adhesive layer for laser-processed films can be obtained by applying a solution containing the components of the adhesive layer for laser-processed films onto a light-absorbing substrate, and then drying the solution to remove the solvent. In another example, a laser-processed film can be obtained by separately forming the light-absorbing substrate and the adhesive layer for laser-processed films, and then attaching the adhesive layer for laser-processed films to the light-absorbing substrate. Examples of this method include air-cooled inflation molding, T-die film molding, and water-cooled inflation molding. In yet another example, a laser-processed film can be obtained by performing the formation and lamination of the light-absorbing substrate and the adhesive layer for laser-processed films in the same process by extrusion. Examples of these methods include extrusion lamination, dry lamination, sandwich lamination, and co-extrusion.

[0025] <Laser processing method> The laser-processed film of the present invention can be used to perform laser processing on a workpiece. Compared to conventional press processing such as punching thin sheets, laser processing allows for the setting and processing of specific, complex shapes, eliminates the need for molds, and can accommodate precision processing and thick plate processing. In one example of a laser processing method, the laser-processed film of the present invention is attached to one surface of the workpiece. The workpiece is not particularly limited as long as it is a metal plate, but stainless steel is preferred. The stainless steel is not particularly limited and includes austenitic stainless steel (SUS304, SUS316, etc.), ferritic stainless steel (SUS430, etc.), martensitic stainless steel (SUS410, SUS440, etc.), duplex stainless steel (SUS329J1, etc.), and precipitation-hardening stainless steel (SUS630, etc.). For example, a stainless steel 304HL finished plate can be processed as the stainless steel plate. When attaching the laser-processed film to one surface of the workpiece, the attachment of the laser-processed film may be promoted by pressing it with a predetermined load.

[0026] Next, a laser is irradiated onto the workpiece from the side where the laser-processed film is attached, while simultaneously spraying gas. At this time, the laser passing through the laser-processed film is further irradiated onto the workpiece, melting it and allowing it to be cut and processed into the desired shape. In addition, the gas blows away and removes molten material and fragments from the workpiece during laser irradiation, reducing the risk of the workpiece re-solidifying and causing problems such as the formation of slag and dross.

[0027] Here, the adhesive layer for the laser-processed film constituting the laser-processed film of the present invention has an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min when the evaluation film is peeled from the stainless steel plate, and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min. Therefore, there is no peeling of the laser-processed film due to gas jetting during laser processing.

[0028] Next, the laser-processed film is peeled off the substrate. The peeling speed when peeling off the laser-processed film is not particularly limited, but it is preferably 0.3 to 10 m / min, more preferably 0.3 to 5 m / min, and even more preferably 0.3 to 1 m / min. At this time, the adhesive layer for the laser-processed film constituting the laser-processed film of the present invention has an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min, an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min, and preferably an adhesive force of 3.5 to 7.0 N / 25 mm at a peeling speed of 0.3 m / min when the evaluation film is peeled off the stainless steel plate.Therefore, it is possible to have excellent peelability from the substrate after laser processing.

[0029] While there are no particular limitations on the lasers used in laser processing methods, examples include gas lasers such as CO2 lasers and solid-state lasers such as fiber lasers. CO2 lasers generate laser light by exciting a mixture of gases such as carbon dioxide, nitrogen, and helium through electrical discharge. Fiber lasers generate laser light by using an optical fiber as a medium and amplifying light within a glass fiber doped with rare earth elements. While there are no particular limitations on the gases used, examples include compressed air, nitrogen, and oxygen. [Examples]

[0030] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited in any way to the following examples.

[0031] Adhesive resins 1 to 8 for the adhesive layer of laser-processed film were prepared as follows. (Adhesive resin 1) In a polymerization reactor equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet, 51.51 parts by mass of deionized water, 0.19 parts by mass of potassium persulfate as a polymerization initiator, 42.17 parts by mass of 2-ethylhexyl acrylate as monomers, 4.83 parts by mass of acrylonitrile, 0.77 parts by mass of acrylic acid, 0.36 parts by mass of N-methylolacrylamide, 0.02 parts by mass of t-dodecyl mercaptan as a molecular weight modifier, and 0.15 parts by mass of sodium alkyldiphenyl ether disulfonate as a surfactant were added, and emulsion polymerization was carried out at 70°C for 8 hours with stirring under a nitrogen atmosphere. The resulting emulsion was neutralized with aqueous ammonia solution (pH=7.0). By the above procedure, an adhesive resin solution 1 containing 47.3 parts by mass of adhesive resin was obtained. Next, to obtain the adhesive resin 1, a crosslinking agent and an organic solvent were added in a ratio of 0.15 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) and 0.15 parts by mass of diethylene glycol monobutyl ether as an organic solvent, respectively, per 100 parts by mass of the adhesive resin solution 1.

[0032] (Adhesive resin 2) To 100 parts by mass of the same adhesive resin solution 1 used to prepare the adhesive resin 1 described above, 0.2 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) and 0.2 parts by mass of diethylene glycol monobutyl ether were added as a crosslinking agent and organic solvent to obtain adhesive resin 2.

[0033] (Adhesive resin 3) In a polymerization reactor equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet, 54.31 parts by mass of deionized water, 0.23 parts by mass of potassium persulfate as a polymerization initiator, 18.89 parts by mass of 2-ethylhexyl acrylate, 18.89 parts by mass of butyl acrylate, 3.60 parts by mass of acrylonitrile, 2.25 parts by mass of methacrylic acid, 1.35 parts by mass of acrylamide, 0.23 parts by mass of 57% divinylbenzene as monomers, and 0.25 parts by mass of sodium alkyldiphenyl ether disulfonate as a surfactant were added, and emulsion polymerization was carried out at 70°C for 8 hours with stirring under a nitrogen atmosphere. The resulting emulsion was neutralized with aqueous ammonia solution (pH=7.0). By the above procedure, an adhesive resin solution 3 containing 44.4 parts by mass of adhesive resin was obtained. To obtain the adhesive resin 3, a crosslinking agent and an organic solvent were added in such proportions as 0.15 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) and 0.15 parts by mass of diethylene glycol monobutyl ether as an organic solvent, respectively, per 100 parts by mass of the above adhesive resin solution 3.

[0034] (Adhesive resin 4) To 100 parts by mass of the same adhesive resin solution 3 used to prepare the above-mentioned adhesive resin 3, 0.2 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) and 0.2 parts by mass of diethylene glycol monobutyl ether were added as a crosslinking agent and organic solvent to obtain adhesive resin 4.

[0035] (Adhesive resin 5) To 100 parts by mass of the same adhesive resin solution 3 used to prepare the above-mentioned adhesive resin 3, 0.4 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) was added as a crosslinking agent, and 0.4 parts by mass of diethylene glycol monobutyl ether was added as an organic solvent to obtain the adhesive resin 5.

[0036] (Adhesive resin 6) In a polymerization reactor equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet, 57.01 parts by mass of deionized water, 0.27 parts by mass of 4-cyanovaleric acid as a polymerization initiator, 31.50 parts by mass of butyl acrylate, 5.81 parts by mass of methyl methacrylate, 3.82 parts by mass of 2-hydroxyethyl methacrylate, 0.85 parts by mass of methacrylic acid, 0.42 parts by mass of acrylamide as monomers, and 0.32 parts by mass of ammonium=4-nonyl-2-(1-propenyl)phenoxypoly(n=0~29)ethoxyethyl sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-10) as a surfactant were added, and emulsion polymerization was carried out at 70°C for 8 hours with stirring under a nitrogen atmosphere. The resulting emulsion was neutralized with aqueous ammonia solution (pH=7.0). By the above procedure, an adhesive resin solution 6 containing 42.8 parts by mass of adhesive resin was obtained. To obtain the adhesive resin 6, a crosslinking agent and an organic solvent were added in such proportions that 0.15 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) and 0.15 parts by mass of diethylene glycol monobutyl ether were added to 100 parts by mass of the above adhesive resin solution 6.

[0037] (Adhesive resin 7) In a polymerization reactor equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet, 57.79 parts by mass of deionized water, 0.26 parts by mass of 4-cyanovaleric acid as a polymerization initiator, 26.23 parts by mass of 2-ethylhexyl acrylate, 7.49 parts by mass of butyl acrylate, 5.00 parts by mass of methyl methacrylate, 1.25 parts by mass of 2-hydroxyethyl methacrylate, 0.83 parts by mass of methacrylic acid, 0.42 parts by mass of acrylamide, 0.42 parts by mass of polytetramethylene glycol diacrylate (manufactured by NOF Corporation, product name: Bremmer ADT-250), and 0.31 parts by mass of ammonium=4-nonyl-2-(1-propenyl)phenoxypoly(n=0~29)ethoxyethyl sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-10) as a surfactant were added, and emulsion polymerization was carried out at 70°C for 8 hours with stirring under a nitrogen atmosphere. The resulting emulsion was neutralized with an aqueous ammonia solution (pH=7.0). By the above procedure, an adhesive resin solution 7 containing 42.0 parts by mass of adhesive resin was obtained. To 100 parts by mass of the above adhesive resin solution 7, 0.15 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) was added as a crosslinking agent, and 0.15 parts by mass of diethylene glycol monobutyl ether was added as an organic solvent to obtain an adhesive resin 7.

[0038] (Adhesive resin 8) In a polymerization reactor equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet, 43.62 parts by mass of deionized water, 0.28 parts by mass of potassium peroxydisulfate as a polymerization initiator, 35.17 parts by mass of 2-ethylhexyl acrylate, 11.72 parts by mass of butyl acrylate, 5.02 parts by mass of methyl methacrylate, 1.67 parts by mass of 2-hydroxyethyl methacrylate, 1.12 parts by mass of methacrylic acid as monomers, 0.56 parts by mass of acrylamide, 0.56 parts by mass of polytetramethylene glycol diacrylate (manufactured by NOF Corporation, product name: Bremmer ADT-250), and 0.28 parts by mass of ammonium=4-nonyl-2-(1-propenyl)phenoxypoly(n=0~29)ethoxyethyl sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-10) as a surfactant were added, and emulsion polymerization was carried out at 70°C for 8 hours with stirring under a nitrogen atmosphere. The resulting emulsion was neutralized with an aqueous ammonia solution (pH=7.0). By the above procedure, an adhesive resin solution 8 containing 56.1 parts by mass of adhesive resin was obtained. To 100 parts by mass of the above adhesive resin solution 8, a crosslinking agent and an organic solvent were added in the following proportions: 0.15 parts by mass of sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name: Denacol EX-614) as the crosslinking agent and 0.15 parts by mass of diethylene glycol monobutyl ether as the organic solvent to obtain an adhesive resin 8.

[0039] [Reference example 1] An aqueous ammonia solution was added to adhesive resin 1 to adjust the pH to 9, and the viscosity was adjusted to 100 mPa·s using pure water to obtain adhesive solution 1.

[0040] [Reference examples 2~8] Adhesive solutions 2 to 8 were prepared in the same manner as in Reference Example 1, except that adhesive resins 2 to 8 were used instead of adhesive solution 1, as shown in Table 1 below. The pH of each adhesive solution 2 to 8 was adjusted to 7.5 to 9.5 by adding an aqueous ammonia solution, and the viscosity was adjusted to 20 to 200 mPa·s using pure water.

[0041] Using the adhesive solutions 1 to 8 obtained as described above, the following were evaluated: (a) adhesive strength when the evaluation film was peeled off at peeling speeds of 0.003 m / min, 0.03 m / min, and 0.3 m / min; (b) laser processability; and (c) adhesive residue. The measurement methods for the above characteristics (a) to (c) are described below.

[0042] (a) Measurement of adhesive strength when the evaluation film is peeled off at peeling speeds of 0.003 m / min, 0.03 m / min, and 0.3 m / min. <Method for preparing evaluation films> 0.90~0.96 g / cm³ 3 Low-density polyethylene (LDPE) film having a specific density within the range (manufactured by Tamapoly Co., Ltd., product name: M-6, thickness 90 μm, 0.93 g / cm²) 3 One of the adhesive solutions 1 to 8 obtained in Reference Examples 1 to 8 was applied to the substrate. After that, the solution was dried to form an adhesive layer for laser processing films having a thickness of 5 to 12 μm, thereby producing an evaluation film. The evaluation films obtained using the adhesive solutions 1 to 4 obtained in Reference Examples 1 to 4 were designated as Examples 1 to 4, and the evaluation films obtained using the adhesive solutions 5 to 8 obtained in Reference Examples 5 to 8 were designated as Comparative Examples 1 to 4. The adhesive strength of the evaluation films thus produced was measured according to the following procedure. The obtained adhesive strength results are shown in Table 1.

[0043] <Measuring Adhesion> A stainless steel 304HL finished plate (JIS G4305 2021 standard; stainless steel plate) measuring 50 mm in width, 200 mm in length, and 0.6 mm in thickness was prepared. The surface of the finished stainless steel plate was then degreased with ethanol and dried to serve as the substrate. Under an atmosphere of 23°C and 50% RH, the evaluation films obtained in Examples 1-4 and Comparative Examples 1-4 were cut to a length of 100 mm and a width of 25 mm, and temporarily attached to the surface of the finished stainless steel plate using a hand roller so that the adhesive layer for the laser-processed film was in contact with it. After this, a pressure roller was used to apply a load of 10 kg from the polyethylene base film side at a speed of 2 m / min to press the evaluation film onto the stainless steel plate, and it was left for 24 hours. Next, using a tensile testing machine (ORIENTEC RTA-1210A), one end of the evaluation film was held, and the evaluation film was peeled from the surface of the stainless steel 304HL finished plate at a peeling angle of 180 degrees and peeling speeds of 0.003 m / min, 0.03 m / min, or 0.3 m / min. The strength (N / 25mm) measured at that time was defined as the adhesive strength.

[0044] (b) Laser processability <Method for preparing films for practical evaluation> One of the adhesive solutions 1 to 8 obtained in Reference Examples 1 to 8 was applied to a substrate of low-density polyethylene (LDPE, 90 μm thick) containing carbon black. Afterward, the solution was dried to form an adhesive layer for laser processing films with a thickness of 5 to 12 μm, thereby producing a film for practical evaluation. The practical evaluation films obtained using adhesive solutions 1 to 4 from Reference Examples 1 to 4 were designated as Examples 1 to 4, while the practical evaluation films obtained using adhesive solutions 5 to 8 from Reference Examples 5 to 8 were designated as Comparative Examples 1 to 4. The following evaluations were performed on the prepared practical evaluation films. The results are shown in Table 1 below.

[0045] <Evaluation of laser processability> The surface of a 300mm wide, 300mm long, and 2mm thick stainless steel 304HL finished plate (as specified in JIS G4305 2021; stainless steel plate) was degreased with ethanol and air-dried. After this, using a roller, the practical evaluation films obtained in Examples 1-4 and Comparative Examples 1-4 were bonded to one surface of the stainless steel 304HL finished plate via the adhesive layer for laser processing films. In Examples 1-4 and Comparative Examples 1-4, laser processing was performed on the stainless steel 304HL finished plate 10 to which the practical evaluation film had been bonded, so that a workpiece of a predetermined shape as shown in Figure 2 could be obtained. More specifically, in Examples 1-4 and Comparative Examples 1, 2, and 4, a Mitsubishi Electric ML3015 GX-F100 fiber laser processing machine was used, operating under the conditions of output 4.0kW, speed 21m / min, gas: nitrogen (gas injection pressure: 0.9MPa), nozzle focus -1.5mm, and nozzle height 1.5mm relative to the test film. Laser processing was performed by irradiating a stainless steel 304HL finished plate 10, to which the practical evaluation film had been laminated, from the practical evaluation film side. In contrast, in Comparative Example 3, a Mitsubishi Electric ML3015HV2-R-45CF-R CO2 laser processing machine was used, operating under the conditions of output 4.0kW, speed 4m / min, gas: nitrogen (gas injection pressure: 0.9MPa), and nozzle focus -1.5mm. Laser processing was performed by irradiating a stainless steel 304HL finished plate 10, to which the practical evaluation film had been laminated, from the practical evaluation film side. In this process, laser processing was possible without the evaluation film peeling off, and was marked with a "○" if the evaluation film peeled off. The results are shown in Table 1 below.

[0046] (c) Adhesive residue Similarly to (b) above, the adhesive residue was visually inspected when a practical evaluation film was peeled off by hand from stainless steel 304 No.2B finish (JIS G4305 2021 standard; stainless steel plate) that had undergone laser processing. Then, plates with no adhesive residue were evaluated as "○" and plates with adhesive residue were evaluated as "×". The results obtained are shown in Table 1 below.

[0047] [Table 1]

[0048] As shown in Table 1 above, Examples 1 to 4 have an adhesive strength of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min, 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min, and 3.5 to 7.0 N / 25 mm at a peeling speed of 0.3 m / min. Therefore, in practical evaluations, Examples 1 to 4 were evaluated as "○" for laser processability and adhesive residue, there was no peeling due to gas injection during laser processing, and it was confirmed that they had excellent peelability from the metal plate after laser processing. On the other hand, Comparative Examples 1 to 4 have an adhesive strength of less than 0.7 N / 25 mm or more than 2.5 N / 25 mm at a peeling speed of 0.003 m / min, and an adhesive strength of less than 2.0 N / 25 mm or more than 4.0 N / 25 mm at a peeling speed of 0.03 m / min. Therefore, in Comparative Examples 1 to 4, the practical evaluation showed that laser processability or adhesive residue was "X," confirming that it was not possible to achieve both prevention of peeling due to gas injection during laser processing and excellent peelability from the metal plate after laser processing. [Explanation of Symbols]

[0049] 1. Laser-cut film 2. Light-absorbing substrate 3. Adhesive layer for laser-processed film 10 Stainless steel plate

Claims

1. An adhesive layer for laser-processed films, 0.90~0.96g / cm ３ An evaluation film having the adhesive layer for laser-processed films provided on a polyethylene substrate having a density and a thickness of 90 μm is attached to a stainless steel plate, and when the evaluation film is peeled off the stainless steel plate, the adhesive layer for laser-processed films has an adhesive force of 0.7 to 2.5 N / 25 mm at a peeling speed of 0.003 m / min and an adhesive force of 2.0 to 4.0 N / 25 mm at a peeling speed of 0.03 m / min.

2. The adhesive layer for laser-processed film according to claim 1, wherein when the evaluation film is peeled off the stainless steel plate, it has an adhesive strength of 3.5 to 7.0 N / 25 mm at a peeling speed of 0.3 m / min.

3. The adhesive layer for laser-processed films according to claim 1 or 2, wherein when the evaluation film is peeled off from the stainless steel plate, it has an adhesive strength of 0.7 to 2.0 N / 25 mm at a peeling speed of 0.003 m / min.

4. Light-absorbing substrate and On the light-absorbing substrate, an adhesive layer for laser-processed films according to claim 1 or 2 A laser-processed film having the following properties.

5. The laser-processed film according to claim 4, wherein the light-absorbing substrate contains carbon black.

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