CN116496705A

CN116496705A - Adhesive film, laminate, and method for using adhesive film

Info

Publication number: CN116496705A
Application number: CN202310055878.4A
Authority: CN
Inventors: 长谷部真生; 片野大地; 武井秀晃; 江头达也; 高桥佑辅
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2022-01-27
Filing date: 2023-01-20
Publication date: 2023-07-28

Abstract

The invention provides an adhesive film, which is not prevented from eliminating residual stress and deformation of a resin film when the resin film is annealed in a state that the resin film is temporarily fixed, is not easy to be peeled off from the resin film, and is easy to be peeled off after the annealing treatment and is free from residual glue. An adhesive film comprising a base material and an adhesive layer provided on at least one surface of the base material, wherein the adhesive layer has a temperature range of 70-100 ℃ and a loss tangent tan delta of 0.8 or more, and can be peeled off by irradiation with active energy rays.

Description

Adhesive film, laminate, and method for using adhesive film

Technical Field

The present invention relates to an adhesive film and the like which can be applied to, for example, conveyance of a resin film requiring an annealing treatment such as an optical film, surface protection, and the like.

Background

Industrial films are used for articles in various fields such as displays, electronics, batteries or energy sources, vehicles (automobiles), etc., to impart or exert desired functions. For example, optical films such as polarizing films and retardation films used in the display field are used as components of image display devices such as liquid crystal displays and organic EL displays mounted on electronic terminals such as smartphones and tablet computers.

In each process of manufacturing, processing, handling, and inspection of articles in various fields, an adhesive film is bonded to the surface of an industrial film for the purpose of handling the industrial film assembled in the articles and for the purpose of protecting the surface from damage and contamination. The adhesive film is peeled off and removed from the industrial film at an unnecessary stage. For example, patent document 1 discloses an adhesive film for protecting and conveying the surface of an optical film in the process of manufacturing a display device. Such an adhesive film is sometimes referred to as a protective film, a process film, or the like, depending on the method of use.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2013-216738

Disclosure of Invention

Problems to be solved by the invention

Resin films used in industrial films are usually annealed for the purpose of removing residual stress and strain generated during the molding process. When the resin film is annealed in a state where the adhesive film is previously bonded to the resin film, the resin film is restrained by the adhesive film and the deformation of the resin film is suppressed, and even when the annealing is performed, the residual stress and the deformation cannot be sufficiently removed, which results in a problem that defects occur in the subsequent processing steps.

The heating temperature and the treatment time in the annealing treatment are set according to the glass transition temperature of the resin film. The adhesive film bonded to the resin film is required to be less likely to peel off even in the annealing environment of the resin film, and to be easily peeled off from the resin film after the annealing.

That is, an object of the present invention is to provide an adhesive film which does not prevent the elimination of residual stress and deformation of a resin film when the resin film is annealed in a state where the resin film is temporarily fixed, is not easily peeled off from the resin film, and can be easily peeled off after the annealing treatment without leaving a residual adhesive.

Means for solving the problems

The present invention includes the following modes.

[1] An adhesive film, characterized in that,

the adhesive film has a base material and an adhesive layer provided on at least one surface of the base material,

the pressure-sensitive adhesive layer has a temperature range of 0.8 or more in terms of loss tangent tan delta at a frequency of 1Hz in a range of 70-100 ℃,

the adhesive film can be peeled off by irradiation with active energy rays.

[2] An adhesive film, characterized in that,

The adhesive layer is formed from an adhesive composition containing an acrylic copolymer and an active energy ray-curable compound, and has a temperature range in which the loss tangent tan delta at a frequency of 1Hz is 0.8 or more in the range of 70-100 ℃.

[3] The adhesive film according to the item [1] or [2], wherein the gel fraction of the adhesive layer is 50% by mass or less.

[4] The adhesive film according to any one of the above [1] to [3], wherein the substrate has a 100% elongation stress value at 150℃of 5MPa to 60MPa.

[5] The adhesive film according to any one of the above [1] to [4], wherein the adhesive film is used by bonding to a resin film.

[6] The adhesive film according to any one of [1] to [5], wherein the adhesive film is used for surface protection.

[7] The adhesive film according to any one of the above [1] to [6], wherein the adhesive film is used for a conveying process.

[8] A laminate body, characterized in that,

the laminate comprises the adhesive film according to any one of [1] to [7], and a resin film provided on the adhesive layer of the adhesive film.

[9] The laminate according to item [8], wherein the resin film is an optical film.

[10] A method for using an adhesive film, comprising the following steps in order:

a step of bonding a resin film to the adhesive layer of the adhesive film according to any one of the above [1] to [7] to obtain a laminate;

annealing the resin film of the laminate; and

and a step of irradiating the laminate after the annealing step with active energy rays to peel off the adhesive film from the resin film.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of an adhesive film of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of the laminate of the present invention.

Fig. 3 is an explanatory view for explaining a curl test method in examples and comparative examples.

Fig. 4 is an explanatory view for explaining a thermoforming test method in examples and comparative examples.

Fig. 5 is an explanatory view for explaining a thermoforming test method in examples and comparative examples.

Fig. 6 is an explanatory view for explaining a thermoforming test method in examples and comparative examples.

Detailed Description

In the present invention, "(meth) acrylic" means acrylic acid or methacrylic acid. In addition, "(meth) acrylate" means an acrylate or a methacrylate. The loss tangent tan δ may be abbreviated as tan δ.

1. Adhesive film

The adhesive film of the present invention is characterized by comprising a base material and an adhesive layer provided on at least one surface of the base material, wherein the adhesive layer has a temperature range of 0.8 or more in terms of loss tangent tan delta in the range of 70-100 ℃, and the adhesive film can be peeled off by irradiation with active energy rays.

In other words, the adhesive film of the present invention comprises a base material and an adhesive layer provided on at least one surface of the base material, wherein the adhesive layer is formed from an adhesive composition comprising an acrylic copolymer and an active energy ray-curable compound, and has a temperature range in which the loss tangent tan δ is 0.8 or more in the range of 70 ℃ to 100 ℃.

Fig. 1 is a schematic cross-sectional view showing an example of an adhesive film of the present invention, which has a substrate 1 and an adhesive layer 2 provided on one surface of the substrate 1. The pressure-sensitive adhesive layer 2 has a temperature range in which the loss tangent tan delta is 0.8 or more in the range of 70 to 100 ℃. The pressure-sensitive adhesive layer 2 is peelable by irradiation with active energy rays. In other words, the pressure-sensitive adhesive layer 2 is a layer formed from a pressure-sensitive adhesive composition containing an acrylic copolymer and an active energy ray-curable compound.

The heating temperature and heating time set in the annealing treatment are selected according to the type and physical properties of the resin (for example, glass transition temperature of the resin). Among them, a resin film used for an optical film or the like is annealed at a temperature of about 100 ℃ to suppress the deterioration of the function of the resin film due to the heat of the annealing treatment. However, if the annealing treatment is performed in a state where the adhesive film is bonded, the resin film is constrained by the adhesive film, and residual stress and strain cannot be sufficiently eliminated, which has a problem that workability and optical characteristics of the annealed resin film are affected.

In contrast, according to the adhesive film of the present invention, the adhesive layer has a temperature range in which the loss tangent tan δ is 0.8 or more in the range of 70 to 100 ℃, and thus the adhesive layer can exhibit flexibility and fluidity in the temperature environment at the time of annealing of the resin film, and the adhesive layer does not interfere with the deformation of the resin film generated during the annealing, and can sufficiently eliminate the residual stress and deformation of the resin film in a state where the adhesive film is bonded.

In addition, the adhesive film of the present invention can exhibit excellent adhesive force before irradiation with active energy rays, and therefore is not easily peeled from the resin film even when heated by annealing treatment, and can be easily peeled from the resin film by irradiation with active energy rays without leaving a residual adhesive when peeled from the resin film after annealing treatment.

The adhesive layer of the adhesive film of the present invention has the above-described physical properties, and therefore, when the resin film is annealed in a temperature range of about 100 ℃, for example, 70 ℃ or more and 100 ℃ or less (sometimes referred to as a low temperature range), and when the resin film is annealed in a temperature range exceeding 100 ℃ (sometimes referred to as a high temperature range), the adhesive layer can exhibit the above-described functions, and therefore, deformation due to elimination of residual stress and deformation of the resin film is not inhibited, and further, the adhesive state between the resin film and the adhesive film is maintained before irradiation with active energy rays, and good peelability can be exhibited by irradiation with active energy rays. Therefore, for example, the functional resin film such as an optical film is annealed in a low temperature region in a state where the adhesive film of the present invention is bonded, whereby the function of the resin film is prevented from being impaired, and the residual stress and deformation of the resin film can be eliminated in a state where the adhesive film is bonded, and the surface protection and transportation can be performed.

In the present invention, unless otherwise specified, tan δ of the adhesive layer refers to tan δ of the adhesive layer before the annealing treatment and before curing (before irradiation with active energy rays) of the resin film. Unless otherwise specified, the physical properties of the adhesive layer other than tan δ refer to the physical properties of the adhesive layer before the annealing treatment and before the curing (before the irradiation of active energy rays) of the resin film.

[ adhesive layer ]

The pressure-sensitive adhesive layer in the present invention is provided on at least one surface of the base material. The pressure-sensitive adhesive layer may be provided directly on the surface of the substrate or may be provided on the surface of the substrate via another layer.

In the present invention, the adhesive layer is a layer having an adhesive force after irradiation with active energy rays smaller than an adhesive force before irradiation with active energy rays. The adhesive layer in the present invention has the following characteristics: while the adhesive strength is excellent before the irradiation of the active energy ray, the adhesive strength is lowered by the curing reaction by the irradiation of the active energy ray. That is, the adhesive layer in the present invention is formed of an adhesive composition cured by active energy rays (an active energy ray-curable adhesive composition may be formed).

The active energy ray may be any ray that can cure the pressure-sensitive adhesive layer, and may be an electromagnetic wave such as far ultraviolet ray, near ultraviolet ray, infrared ray, or the like, an electron ray, a proton ray, a neutron ray, or the like. Among them, ultraviolet rays are preferable from the viewpoints of high curing speed, simple irradiation operation and simple irradiation apparatus.

The adhesive layer of the present invention has a temperature range in which the loss tangent tan delta is 0.8 or more in the range of 70 to 100 ℃. By providing the pressure-sensitive adhesive layer with a temperature range in which the pressure-sensitive adhesive layer exhibits a specific tan δ in the above temperature range, the pressure-sensitive adhesive layer can exhibit high flexibility and fluidity in an annealing environment when the resin film is annealed in a state of being bonded to the pressure-sensitive adhesive film. Thus, the adhesive layer does not interfere with the deformation of the resin film that occurs during the annealing treatment, and the residual stress and deformation of the resin film can be sufficiently eliminated in a state where the adhesive film is bonded.

The pressure-sensitive adhesive layer may have a temperature range of 0.8 or more in which tan δ is present in a range of 70 to 100 ℃, and preferably has a temperature range of 0.8 or more in a range of 80 to 100 ℃, more preferably has a temperature range of 0.8 or more in a range of 85 to 100 ℃, and still more preferably has a temperature range of 0.8 or more in a range of 90 to 100 ℃. By having the temperature range in which the tan δ is 0.8 or more, deformation due to elimination of residual stress and deformation of the resin film generated during the annealing process can be prevented from being hindered by the adhesive layer, and the conformality of the adhesive layer can be ensured.

The pressure-sensitive adhesive layer of the present invention can exhibit tan delta of 0.8 or more in a temperature range exceeding 100 ℃ by having a temperature range of tan delta of 0.8 or more in a range of 70 ℃ to 100 ℃. Therefore, even when the annealing treatment of the resin film is performed in a temperature range of 100 ℃ or less, and when the annealing treatment is performed in a temperature range exceeding 100 ℃, the adhesive layer does not interfere with deformation associated with the elimination of residual stress and deformation of the resin film, and can eliminate the residual stress and deformation of the resin film.

The pressure-sensitive adhesive layer may have a temperature range of 70 to 100 ℃ in which tan δ is 0.8 or more, preferably a temperature range of 0.80 or more, and more preferably a temperature range of 0.87 or more, and even more preferably a temperature range of 0.93 or more, and further preferably a temperature range of 1.0 or more, and may exhibit higher flexibility and fluidity in the annealing treatment environment of the resin film, and the pressure-sensitive adhesive layer does not interfere with the elimination of residual stress and strain of the resin film, and can eliminate the residual stress and strain of the resin film. The upper limit of tan δ in the range of 70 to 100 ℃ of the pressure-sensitive adhesive layer is not particularly limited if the flexibility and fluidity of the pressure-sensitive adhesive layer and the shape retention property as the pressure-sensitive adhesive layer can be both achieved in the annealing treatment environment of the resin film, and for example, tan δ may be 2.0 or less, and is preferably 1.5 or less and 1.3 or less from the viewpoint of eliminating residual stress and deformation of the resin film and improving the processing adaptability and shape retention property of the pressure-sensitive adhesive film.

In the annealing treatment environment of the resin film bonded to the adhesive film of the present invention, the tan δ of the adhesive layer is preferably 0.80 or more in a temperature range of 75 to 100 ℃ from the viewpoint of both the appearance of the flexibility and fluidity of the adhesive layer and the shape retention as the adhesive layer, wherein the tan δ is preferably 0.87 or more, more preferably 0.93 or more, still more preferably 1.0 or more, and further preferably 2.0 or less, more preferably 1.5 or less.

As another preferred embodiment, the adhesive layer preferably has a tan δ of 0.80 or more in a temperature range of 80 to 100 ℃, and among them, it is preferably 0.87 or more, more preferably 0.93 or more, further preferably 1.0 or more, and further preferably has a tan δ of 2.0 or less, more preferably 1.5 or less, further preferably 1.3 or less.

As another preferred embodiment, the adhesive layer preferably has a tan δ of 0.80 or more in a temperature range of 85 to 100 ℃, and among them, it is preferably 0.87 or more, more preferably 0.93 or more, further preferably 1.0 or more, and further preferably has a tan δ of 2.0 or less, more preferably 1.5 or less, further preferably 1.3 or less.

As another preferred embodiment, the adhesive layer preferably has a tan δ of 0.80 or more in a temperature range of 90 to 100 ℃, and among them, it is preferably 0.87 or more, more preferably 0.93 or more, further preferably 1.0 or more, and further preferably has a tan δ of 2.0 or less, more preferably 1.5 or less, further preferably 1.3 or less.

More specifically, the loss tangent tan δ (90 ℃) at 90 ℃ is preferably 0.8 or more, and among these, it is preferably 0.80 or more, more preferably 0.87 or more, and tan δ is 0.93 or more, whereby the adhesive layer is excellent in shape retention even at the ambient temperature of the resin film annealing treatment, and the adhesive layer can exhibit high flexibility and fluidity at the ambient temperature of the resin film annealing treatment, and can suppress the adhesive layer from impeding elimination of residual stress and deformation of the resin film.

The maximum loss tangent tan δ of the pressure-sensitive adhesive layer in a temperature range of 50 ℃ or more and less than 70 ℃ is preferably 1.5 or less, more preferably 1.3 or less, and further preferably 1.0 or less. This is because the adhesive layer can be prevented from exhibiting excessive fluidity in the temperature environment of the annealing treatment of the resin film bonded to the adhesive film, and the dimensional stability as a layer can be impaired.

The loss tangent tan δ of the pressure-sensitive adhesive layer can be adjusted by, for example, adjusting the gel fraction of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer; adjusting the amount of the crosslinking agent; reducing the weight average molecular weight of the acrylic copolymer contained in the adhesive composition; the content of the active energy ray-polymerizable compound (also referred to as "active energy ray-curable compound", for example, urethane (meth) acrylate) contained in the adhesive composition is adjusted by a method such as increasing the content.

The loss tangent tan δ of the adhesive layer refers to: the ratio of the loss modulus g″ to the storage modulus G ', i.e., tan δ=g "/G', of the adhesive composition used to form the adhesive layer. The loss tangent tan delta of the adhesive layer was measured by: the adhesive composition for forming an adhesive layer was applied to the surface of a release liner, the adhesive layer a having a thickness of 50 μm was prepared by heating at 85℃for 5 minutes using an oven, the adhesive layer a thus obtained was superimposed, an adhesive layer A having a total thickness of 2mm was prepared, the adhesive layer A was cut into a round shape having a diameter of 8mm to obtain test pieces, a viscoelasticity tester (trade name: ares2 KSTD) was used, the test pieces were sandwiched between parallel disks as a measuring part of the tester, and in a shear stress measuring mode, a storage modulus (G ') and a loss modulus (G ") at a frequency of 1Hz were measured at a temperature rise rate of 2.0 ℃/min and a temperature of-40℃to 150℃and the loss tangent tan delta at each temperature was calculated from the G', G″ at each temperature.

The gel fraction of the pressure-sensitive adhesive layer with respect to toluene (gel fraction before irradiation with active energy rays) is preferably 50 mass% or less, more preferably 10 mass% to 40 mass%, and still more preferably 15 mass% to 35 mass%. By setting the gel fraction of the adhesive layer to the above range, the adhesive property to the resin film is excellent at normal temperature and in an annealing treatment environment before irradiation with active energy rays. In addition, when the gel fraction of the adhesive layer is within the above range, the adhesive layer does not interfere with the deformation of the resin film generated during the annealing treatment, and the residual stress and deformation of the resin film can be sufficiently eliminated in a state where the adhesive film is bonded.

The gel fraction of the adhesive layer and the adhesive composition constituting the adhesive layer means: the obtained values were measured by the methods shown below.

(measurement method)

The pressure-sensitive adhesive composition was applied to the release treated surface of the release liner so that the thickness thereof became 10 μm after drying, and after drying at 85℃for 5 minutes, the pressure-sensitive adhesive layer was cured at 40℃for 2 days, and the pressure-sensitive adhesive layer was cut into square shapes of 50mm in the longitudinal direction and 50mm in the transverse direction as test pieces. After measuring the mass (G1) of the test piece, the test piece was immersed in toluene at 23℃for 24 hours, and after the immersion, a mixture of the test piece and toluene was filtered using a 300 mesh wire gauze to extract a toluene-insoluble component, and the insoluble component was dried at 110℃for 1 hour, whereby the mass (G2) was measured. Based on the mass (G1), the mass (G2), and the following calculation formula, the gel fraction thereof was calculated.

Gel fraction (% by mass) = (G2/G1) ×100

The gel fraction of the adhesive layer after irradiation with active energy rays with respect to toluene is preferably in the range of 80 mass% or more, more preferably 80 mass% or more and 98 mass% or less, and still more preferably 85 mass% or more and 98 mass% or less. By setting the gel fraction of the adhesive layer after irradiation with active energy rays to the above range, the adhesive layer can be easily peeled off with a light load.

The gel fraction of the adhesive layer after the irradiation with the active energy ray was measured in the same manner as the above method except that the adhesive layer was irradiated with the active energy ray under the following conditions after the formation of the adhesive layer, and the adhesive layer after the irradiation with the active energy ray was cut into squares of 50mm in the longitudinal direction and 50mm in the transverse direction to be used as test pieces.

(active energy ray irradiation conditions)

Light source: electrodeless bulb D bulb manufactured by Heraeus company

Illuminance: 90mW/cm ²

Light amount: 180mJ/cm ²

Illuminance/light meter: ORC UV-M10 light meter manufactured by ORC manufacturing company "

The adhesive layer in the present invention is formed of an active energy ray-curable adhesive composition containing various components for constituting the same. The adhesive composition constituting the adhesive layer in the present invention is not particularly limited as long as it exhibits moderate adhesion before irradiation with active energy rays, and the adhesive composition is preferably an adhesive composition containing an adhesive resin as a main component, as long as the adhesive composition is cured by irradiation with active energy rays to reduce and eliminate the adhesive force. The main components of the adhesive composition are: the adhesive composition contains the components with the highest proportion among the components.

In order to exert the function of reducing and eliminating the adhesive force by irradiation with active energy rays, the adhesive composition may be a composition containing an adhesive resin and an active energy ray-curable compound, or may be a composition in which the adhesive resin itself has active energy ray-curability. In addition, even in the case where the binder resin itself has active energy ray curability, the binder composition may have a composition containing the binder resin having active energy ray curability and the other active energy ray curable compound. The adhesive composition is preferably a composition containing an adhesive resin and an active energy ray-curable compound, since the adhesive resin can exhibit an appropriate adhesive force before irradiation with active energy rays, and the adhesive force can be sufficiently reduced after irradiation by curing the active energy ray-curable compound to be peeled off, and physical properties required before and after irradiation are easily considered.

When the binder resin itself has active energy ray curability, an active energy ray polymerizable group is introduced into the binder resin. Among them, the active energy ray polymerizable group is preferably introduced into the main chain or side chain of the binder resin. In order to distinguish the adhesive resin having no active energy ray polymerizable group from the adhesive resin having an active energy ray polymerizable group, the adhesive resin having an active energy ray polymerizable group in the adhesive resin may be referred to as an active energy ray curable adhesive resin.

< binding resin >)

The adhesive resin is a component for ensuring the adhesive force of the adhesive layer. The binder resin is not particularly limited, and examples thereof include acrylic copolymers, polyurethanes, rubber polymers, polyolefin polymers, and copolymers (polymers) such as silicones. Among them, acrylic copolymers are preferable. That is, the pressure-sensitive adhesive layer is preferably formed of an active energy ray-curable pressure-sensitive adhesive composition containing an acrylic copolymer.

The acrylic copolymer is obtained by copolymerizing monomer components containing an alkyl (meth) acrylate as a main monomer. As the alkyl (meth) acrylate, a (meth) acrylate having 1 to 20 carbon atoms in the alkyl group can be preferably used, wherein the carbon number of the alkyl group is preferably 1 to 12, more preferably 1 to 9, and still more preferably 4 to 9. If the number of carbon atoms in the alkyl group is too large, the adherend may be easily contaminated with the residual glue when the adhesive film is peeled off after the irradiation of active energy rays. The alkyl group may have a linear structure or a branched structure.

Specific examples of the alkyl (meth) acrylate include monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. These may be used alone or in combination of 2 or more. Among them, methyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferably used from the viewpoints of copolymerizability, adhesive property, and the like.

The content of the alkyl (meth) acrylate in the acrylic copolymer is preferably 10 to 99% by mass, preferably 30 to 99% by mass, preferably 50 to 99% by mass, preferably 80 to 98.5% by mass, preferably 90 to 98.5% by mass, of the monomer component constituting the acrylic copolymer. When the content of the alkyl (meth) acrylate is within the above range, the adhesive force before irradiation with active energy rays can be prevented from becoming too low or too high, and the adhesion to the resin film can be improved.

The acrylic copolymer may be a copolymer of an alkyl (meth) acrylate and a highly polar monomer. Examples of the highly polar monomer copolymerized with the alkyl (meth) acrylate include a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having an amide group, and the like, and these monomers may be used alone or in combination of 2 or more.

As the monomer having a hydroxyl group, for example, a hydroxyl group-containing (meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and the like can be preferably used. These may be used alone or in combination of 2 or more. Among them, from the viewpoint of reactivity with a crosslinking agent, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable.

The content of the monomer having a hydroxyl group in the acrylic copolymer is preferably 0.1 to 40% by mass, more preferably 0.2 to 30% by mass, and still more preferably 0.5 to 30% by mass, of the monomer component constituting the acrylic copolymer. When the content of the monomer having a hydroxyl group is within the above range, the adhesive film can be prevented from being contaminated by residual glue or the like when the adhesive film is peeled off after irradiation with active energy rays.

As the monomer having a carboxyl group, (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, 2-mer (meth) acrylic acid, crotonic acid, ethylene oxide modified succinic acid acrylate, and the like can be used. These may be used alone or in combination of 2 or more. Among them, acrylic acid and methacrylic acid are preferable from the viewpoint of copolymerizability.

The content of the monomer having a carboxyl group in the acrylic copolymer is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less, and particularly preferably 0.3% by mass or less, of the monomer component constituting the acrylic copolymer. The content of the monomer having a carboxyl group is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and still more preferably 0.05% by mass or more, of the monomer component constituting the acrylic copolymer. By setting the content of the monomer having a carboxyl group within the above range, deterioration of the resin film can be prevented, and surface contamination of the resin film due to residual glue or the like when peeling the adhesive film after irradiation with active energy rays can be prevented.

Examples of the amide group-containing monomer include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N, N-dimethylacrylamide.

Examples of the other highly polar vinyl monomer include sulfonic acid group-containing monomers such as vinyl acetate, ethylene oxide-modified succinic acid acrylate and 2-acrylamido-2-methylpropanesulfonic acid, and terminal alkoxy-modified (meth) acrylates such as 2-methoxyethyl (meth) acrylate and 2-phenoxyethyl (meth) acrylate.

The acrylic copolymer can be obtained by copolymerizing monomers by a known polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among them, the solution polymerization method or the bulk polymerization method is preferable from the viewpoint of the water resistance of the adhesive composition.

In the case of producing an acrylic copolymer by the solution polymerization method, for example, a monomer component containing an alkyl (meth) acrylate and a polymerization initiator are mixed or added dropwise to an organic solvent, and the mixture is polymerized in a reflux state or at a temperature of usually 50 to 98℃for about 0.1 to 20 hours.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propanol and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.

The polymerization initiator may be a usual radical polymerization initiator, and specifically, azo polymerization initiators such as azobisisobutyronitrile and azobis-dimethylvaleronitrile, peroxide polymerization initiators such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide and cumene hydroperoxide, and the like may be used.

The weight average molecular weight of the acrylic copolymer is preferably 10 to 100 tens of thousands. If the weight average molecular weight of the acrylic copolymer is too small, surface contamination of the resin film due to residual glue or the like is likely to occur when the adhesive film is peeled off after irradiation with active energy rays, and if it is too large, coatability may be lowered.

The molecular weight measurement by GPC method is a standard polystyrene equivalent measured by GPC equipment (HLC-8329 GPC) manufactured by Tosoh corporation, and the measurement conditions are as follows.

Sample concentration: 0.5 mass% (THF solution)

Sample injection amount: 100 mu L

Eluent: THF (tetrahydrofuran)

Flow rate: 1.0 mL/min

Measuring temperature: 40 DEG C

The column comprises: TSKgel, GMHHR-H (20) 2 roots

Protective column: TSKgel HXL-H

A detector: differential refractometer

Molecular weight of standard polystyrene: 1 ten thousand to 2000 ten thousand (manufactured by Tosoh Co., ltd.)

When the binder resin itself has active energy ray curability, an active energy ray curable binder resin obtained by introducing an active energy ray polymerizable group into the binder resin can be used.

Examples of the active energy ray-polymerizable group include groups containing an active energy ray-polymerizable carbon-carbon double bond, and specifically, (meth) acryl and the like can be given. The active energy ray polymerizable group may be bonded to the binder resin via an alkylene group, an alkyleneoxy group, and a polyalkyleneoxy group.

The active energy ray-curable binder resin is not particularly limited, and may be a binder resin obtained by introducing an active energy ray-polymerizable group into the binder resin, and among these, an acrylic resin obtained by introducing an active energy ray-polymerizable group is preferable.

The acrylic resin obtained by introducing an active energy ray polymerizable group is obtained by reacting an acrylic copolymer containing a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, or an epoxy group, with a polymerizable group-containing compound having a substituent reactive with the functional group and an active energy ray polymerizable carbon-carbon double bond (1 to 5 groups per 1 molecule). Examples of the polymerizable group-containing compound include (meth) acryloyloxyethyl isocyanate, methyl isopropenyl- α, α -dimethylbenzyl isocyanate, (meth) acryloyl isocyanate, allyl isocyanate, and glycidyl (meth) acrylate; (meth) acrylic acid, and the like.

< active energy ray-polymerizable Compound >

The active energy ray-polymerizable compound contained in the adhesive composition is not particularly limited as long as it is a compound capable of polymerizing upon irradiation with active energy rays, and examples thereof include compounds (monofunctional or polyfunctional monomers and oligomers) having an active energy ray-polymerizable group. Examples of such active energy ray-polymerizable compounds include active energy ray-polymerizable compounds containing 2 or more ethylenically unsaturated groups (i.e., ethylenically unsaturated compounds).

Specific examples of the active energy ray-polymerizable compound include urethane (meth) acrylate compounds, epoxy (meth) acrylate compounds, polyester (meth) acrylate compounds, polyether (meth) acrylate compounds, and polyfunctional ethylenically unsaturated monomers having 2 or more ethylenically unsaturated groups in 1 molecule other than these acrylate compounds. These may be used alone or in combination of 2 or more.

Among them, the above-mentioned active energy ray-polymerizable compound is preferably a urethane (meth) acrylate compound or a polyfunctional ethylenically unsaturated monomer, from the viewpoint of excellent reactivity by irradiation with active energy rays and releasability after irradiation.

The weight average molecular weight of the active energy ray-polymerizable compound also depends on the type of active energy ray-polymerizable compound, and is preferably 10000 or less, more preferably 5000 or less, and further preferably 1000 or less. The weight average molecular weight of the active energy ray-polymerizable compound is preferably 100 or more, more preferably 300 or more, and further preferably 500 or more.

The number of the ethylenically unsaturated groups of the active energy ray-polymerizable compound may be 2 or more per 1 molecule, and may be appropriately selected according to the type of the active energy ray-polymerizable compound. Among them, the number of ethylenically unsaturated groups is preferably 3 or more, more preferably 3 to 60, and still more preferably 3 to 40. If the number of ethylenically unsaturated groups is too small, the adhesion is not easily lowered even when the irradiation with active energy rays is performed, and the peelability may be lowered.

The content of the active energy ray polymerizable compound in the adhesive composition is not particularly limited as long as the adhesive layer before the irradiation with active energy rays can exhibit excellent adhesive force, and the adhesive force of the adhesive layer can be sufficiently reduced or eliminated by the irradiation with active energy rays, and is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and further preferably 20 parts by weight or more relative to 100 parts by weight of the adhesive resin. The content of the active energy ray-polymerizable compound is preferably 200 parts by weight or less, more preferably 100 parts by weight or less, and still more preferably 80 parts by weight or less, based on 100 parts by weight of the binder resin. When the content of the active energy ray polymerizable compound in the adhesive composition is within the above range, the adhesive film can be easily peeled off by reducing the adhesive force in a short time by irradiation with active energy rays, and surface contamination of the resin film due to the residual adhesive or the like at the time of peeling can be prevented.

(urethane (meth) acrylate-based Compound)

The urethane (meth) acrylate compound is a compound having a urethane bond and a (meth) acryloyl group at the end. The urethane (meth) acrylate compound has active energy ray curability by the action of a (meth) acryloyl group.

As the urethane (meth) acrylate compound, a reaction product of a (meth) acrylate having a hydroxyl group and a polyisocyanate compound can be used. The urethane (meth) acrylate compound may be a reaction product of a (meth) acrylate having a hydroxyl group, a polyisocyanate compound, and a polyol compound. Among them, from the viewpoint of good peeling after irradiation with active energy rays, it is preferable to use a urethane (meth) acrylate compound which is a reaction product of a hydroxyl group-containing (meth) acrylate compound and a polyisocyanate compound.

Examples of the (meth) acrylic acid ester having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol penta (meth) acrylate, caprolactone-modified pentaerythritol tetra (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, ethylene oxide-modified pentaerythritol tri (meth) acrylate, ethylene oxide-modified dipentaerythritol penta (meth) acrylate, ethylene oxide-modified dipentaerythritol hexa (meth) acrylate, and the like.

Among them, (meth) acrylates having a hydroxyl group and having 3 or more acryl groups are preferably used, and specifically, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like are exemplified. In addition, they can be used in 1 kind or in combination of 2 or more kinds.

Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornene diisocyanate, isocyanurate or a polymer compound of these polyisocyanates, allophanate type polyisocyanate, biuret type polyisocyanate, and water-dispersible type polyisocyanate. Among them, aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate, alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate and norbornene diisocyanate are preferable from the viewpoint of reactivity.

Examples of the polyhydric alcohol compound include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, polytetramethylene glycol, 1, 6-hexanediol, neopentyl glycol, cyclohexanedimethanol, hydrogenated bisphenol a, polycaprolactone, trimethylolethane, trimethylolpropane, polytrimethylolpropane, pentaerythritol, sorbitol, mannitol, glycerin, polyglycerol, polytetramethylene glycol; polyether polyols having at least 1 structure of polyethylene oxide, polypropylene oxide, block or random copolymerization of ethylene oxide/propylene oxide; a polyester polyol which is a condensate of the polyol or polyether polyol with a polybasic acid such as maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, adipic acid, isophthalic acid, etc.; caprolactone-modified polyols such as caprolactone-modified polytetramethylene polyol; a polyolefin-based polyol; polybutadiene polyols such as hydrogenated polybutadiene polyol; carboxyl group-containing polyols such as 2, 2-bis (hydroxymethyl) butyric acid, tartaric acid, 2, 4-dihydroxybenzoic acid, 3, 5-dihydroxybenzoic acid, 2-bis (hydroxymethyl) propionic acid, 2-bis (hydroxyethyl) propionic acid, 2-bis (hydroxypropyl) propionic acid, dihydroxymethylacetic acid, bis (4-hydroxyphenyl) acetic acid, 4-bis (4-hydroxyphenyl) valeric acid, and homogentisic acid; and sulfonic acid group-containing or sulfonate group-containing polyols such as sodium 1, 4-butanediol sulfonate.

The method for producing the urethane (meth) acrylate compound is not particularly limited, and a known method can be used. For example, the urethane-forming agent can be produced by mixing a (meth) acrylate having a hydroxyl group with a polyvalent isocyanate compound and, if necessary, the polyvalent alcohol compound in an inert gas atmosphere, and then performing a urethane-forming reaction by a known reaction method. In the case of using the above polyol compound, a method of reacting a (meth) acrylate having a hydroxyl group after pre-reacting a polyol compound with a polyisocyanate compound can be used.

The weight average molecular weight of the urethane (meth) acrylate compound is preferably in the range of 500 to 10000, more preferably in the range of 750 to 5000, and even more preferably in the range of 1000 to 4000. Compatibility with the adhesive resin, particularly when an acrylic copolymer is used as the adhesive resin, the compatibility with the acrylic resin is excellent, and bleeding from the adhesive layer can be prevented, and further, when peeling is performed after irradiation with active energy rays, surface contamination of the resin film due to residual glue or the like can be suppressed.

The content of the urethane (meth) acrylate compound in the adhesive composition may be in the range of 5 to 100 parts by weight, preferably 10 to 90 parts by weight, and more preferably 12 to 80 parts by weight, based on 100 parts by weight of the adhesive resin. When the content of the urethane (meth) acrylate compound in the adhesive composition is within the above range, an adhesive layer excellent in releasability after irradiation with active energy rays can be produced.

(ethylenically unsaturated Compound)

The above-mentioned ethylenically unsaturated compound is a compound having 2 or more ethylenically unsaturated groups in 1 molecule. The number of the ethylenically unsaturated groups in the ethylenically unsaturated compound is not less than 2, preferably 2 to 10, more preferably 3 to 9, and even more preferably 4 to 8. By making the number of ethylenically unsaturated groups within the above range, the adhesive layer after irradiation with active energy rays does not leave a residual gum and can be easily peeled from the resin film.

The ethylenically unsaturated compound is not particularly limited as long as it is a compound having an ethylenically unsaturated group, and is preferably a (meth) acrylate compound. Examples of the ethylenically unsaturated (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide modified bisphenol a-type di (meth) acrylate, propylene oxide modified bisphenol a-type di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, ethoxylated cyclohexanedimethanol di (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, phthalic acid diglycidyl ester di (meth) acrylate, hydroxypivalic acid modified neopentyl glycol di (meth) acrylate, and isocyanuric acid di (meth) acrylate having 2 unsaturated groups; compounds having 3 ethylenically unsaturated groups such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tris (meth) acryloxyethoxy trimethylolpropane, isocyanuric acid ethylene oxide modified triacrylate, caprolactone modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, ethoxylated glycerol triacrylate; compounds having 4 or more ethylenically unsaturated groups such as pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol polyglycidyl ether poly (meth) acrylate, caprolactone-modified dipentaerythritol penta (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, caprolactone-modified pentaerythritol tetra (meth) acrylate, ethylene oxide-modified dipentaerythritol penta (meth) acrylate, ethylene oxide-modified dipentaerythritol hexa (meth) acrylate, and ethylene oxide-modified pentaerythritol tetra (meth) acrylate.

Further, as the ethylenically unsaturated (meth) acrylate compound, a michael adduct of (meth) acrylic acid such as a (meth) acrylic acid dimer, a (meth) acrylic acid trimer, and a (meth) acrylic acid tetramer can be used; 2- (meth) acryloyloxyethyl dicarboxylic acid monoesters such as 2- (meth) acryloyloxyethyl succinic acid monoesters, 2- (meth) acryloyloxyethyl phthalic acid monoesters and 2- (meth) acryloyloxyethyl hexahydrophthalic acid monoesters; etc.

The above-mentioned ethylenically unsaturated compounds may be used alone or in combination of 2 or more.

The content of the ethylenically unsaturated compound in the adhesive composition is preferably 5 parts by weight or more and 100 parts by weight or less relative to 100 parts by weight of the adhesive resin, more preferably 10 parts by weight or more and 80 parts by weight or less, and still more preferably 20 parts by weight or more and 60 parts by weight or less. By setting the content of the ethylenically unsaturated compound in the pressure-sensitive adhesive composition to the above range, a pressure-sensitive adhesive layer excellent in peelability and stain resistance after irradiation with active energy rays can be produced.

< crosslinker >

The adhesive composition preferably contains a crosslinking agent in terms of adjusting the loss tangent of the adhesive layer in a specific temperature range to a specific range to form an adhesive layer having excellent cohesive force. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, melamine-based crosslinking agents, aldehyde-based crosslinking agents, and amine-based crosslinking agents. These crosslinking agents may be used alone or in combination of 2 or more. Among them, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are more preferably used from the viewpoints of reactivity with the binder resin and the active energy ray-polymerizable compound and adhesion to the substrate.

Examples of the isocyanate-based crosslinking agent that can be used include 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, hydrogenated xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4, 4-diisocyanate, isophorone diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1, 5-naphthalene diisocyanate, triphenylmethane triisocyanate, and adducts of these polyisocyanate compounds with polyol compounds such as trimethylolpropane, biuret and isocyanurate of these polyisocyanate compounds.

Examples of the epoxy-based crosslinking agent that can be used include bisphenol a epichlorohydrin-based epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycidyl ether, 1,3 '-bis (N, N-diglycidyl aminomethyl) cyclohexane, N' -tetraglycidyl-m-xylylenediamine, and the like.

The amount of the crosslinking agent in the adhesive composition can be appropriately selected from the range of the tan δ.

< other Components >)

The adhesive composition may contain a photopolymerization initiator in addition to the above components. As the photopolymerization initiator, any compound that generates a radical upon irradiation with active energy rays may be used, and known photopolymerization initiators such as acetophenones, benzoins, benzophenones, thioxanthones, and acylphosphine oxides may be used. These may be used alone or in combination of 2 or more. The content of the photopolymerization initiator in the adhesive composition is not particularly limited, and the amount of the photopolymerization initiator to sufficiently effect curing of the adhesive composition by irradiation with active energy rays can be appropriately set, and for example, can be set to 0.1 parts by weight or more and 20 parts by weight or less relative to 100 parts by weight of the total of the adhesive resin and the active energy ray polymerizable compound.

The pressure-sensitive adhesive composition may contain a tackifying resin in addition to the above components to obtain a pressure-sensitive adhesive layer having more excellent peel adhesion. As the tackifying resin, for example, a rosin-based tackifying resin, a polymerized rosin ester-based tackifying resin, a rosin phenol-based tackifying resin, a stabilized rosin ester-based tackifying resin, a disproportionated rosin ester-based tackifying resin, a hydrogenated rosin ester-based tackifying resin, a terpene-phenol-based tackifying resin, a petroleum resin-based tackifying resin, and a (meth) acrylate-based tackifying resin can be used. These may be used alone or in combination of 2 or more.

The adhesive composition may contain, in addition to the above components, a colorant such as a pigment or a dye, a deterioration inhibitor, an antistatic agent, a flame retardant, an organosilicon compound, a chain transfer agent, a plasticizer, a softener, a filler such as glass or plastic fiber/microsphere, beads, a metal oxide, a metal nitride, a leveling agent, a thickener, a water repellent, an antifoaming agent, and the like.

< adhesive layer >)

The thickness of the pressure-sensitive adhesive layer in the present invention is preferably 200 μm or less, more preferably 1 μm or more and 150 μm or less, and still more preferably 5 μm or more and 100 μm or less. This is because, when the thickness of the pressure-sensitive adhesive layer is within the above range, good adhesion to the resin film before irradiation with active energy rays can be achieved, and the curing reaction can be performed by allowing active energy rays to sufficiently pass through.

[ substrate ]

The substrate in the present invention is a member for supporting the adhesive layer. The base material preferably has strength to be able to carry or protect the resin film, and heat resistance to withstand the annealing treatment environment temperature of the resin film. The substrate is further preferably a substrate having physical properties suitable for processing according to the application of the resin film, and for example, is further preferably a substrate excellent in molding stability when the shape of the resin film is changed during molding.

The substrate may be a substrate that transmits or does not transmit active energy rays, and is preferably a substrate that transmits active energy rays from the viewpoint of being able to peel the adhesive film by irradiating the adhesive layer with active energy rays through the substrate. The total light transmittance of the base material is not particularly limited as long as it can sufficiently transmit active energy rays, and is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, and particularly preferably 95% or more.

Examples of the substrate include a resin film, a metal foil, paper, a woven fabric, and a nonwoven fabric. Among them, the resin film is preferable from the viewpoints of operability and active energy ray transmittance.

Examples of the resin film include polyester resin films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film; polyolefin resin films such as polyethylene, polypropylene, and polymethylpentene; cycloolefin polymer, cyclic olefin resin film such as polymer having norbornene structure; fluororesin films such as polyvinyl fluoride, polyvinylidene fluoride, and polyvinyl fluoride; polyamide resin films such as nylon 6 and nylon 66; polyimide resin films such as polyether imide; vinyl polymer resin films such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, vinylon, and the like; cellulose resin films such as diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate and cellophane; acrylic resin films such as polymethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; sulfone resin membranes such as polysulfone membranes and polyether sulfone membranes; a polystyrene resin film; a polycarbonate resin film; polymethylpentene film, polyetheretherketone film, and the like. Among them, from the viewpoint of having both processing suitability for molding processing accompanied by heat and suitable tensile strength capable of being peeled off without breaking after processing, polyester-based resin films, acrylic-based resin films, and polycarbonate-based resin films are preferable, and polyethylene terephthalate films are more preferable.

The substrate may have a single-layer structure composed of only 1 layer, or may have a laminated structure in which 2 or more layers are laminated. In the case where the substrate is formed by stacking 2 or more layers, the layers may be the same or different.

The substrate may have an easily adhesive layer on the surface thereof, or may be subjected to surface treatment for the purpose of improving adhesion to the adhesive layer. Examples of the surface treatment include surface irregularities treatment by a sand blasting method, a solvent treatment method, etc., corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone treatment, ultraviolet irradiation treatment, etc., and other oxidation treatments.

In the case of molding a resin film by heat such as shaping, bending, or three-dimensional molding, the adhesive film of the present invention is integrally molded with the resin film in a state where the adhesive film is bonded to the resin film, whereby the surface of the resin film during molding can be protected.

The stress at 100% elongation at 150 ℃ of the base material is not particularly limited, and can be set appropriately according to the physical properties required for the adhesive film, and from the viewpoint of the formability of the adhesive film, the stress at 100% elongation at 150 ℃ is preferably 5MPa or more and 60MPa or less, more preferably 10MPa or more and 50MPa or less, still more preferably 15MPa or more and 45MPa or less, and still more preferably 15MPa or more and 40MPa or less. If the amount is within the above range, the adhesive film can easily follow the shape of the resin film when the resin film is subjected to the thermoforming process in a state of being bonded to the adhesive film, and thus, occurrence of processing defects such as wrinkles can be prevented, and the molding stability is excellent.

The elongation at break of the base material at 150 ℃ is not particularly limited and can be appropriately set according to the physical properties required for the adhesive film, and from the viewpoint of the formability of the adhesive film, the elongation at break at 150 ℃ is preferably 500% or less, more preferably 100% or more and 400% or less, still more preferably 120% or more and 300% or less, and particularly preferably 120% or more and 250% or less. When the resin film is subjected to the thermoforming process in a state of being bonded to the adhesive film, the adhesive film easily follows the processed shape of the resin film, and deformation and breakage of the base material due to the application of heat can be prevented.

The stress at 100% elongation at 150℃and the elongation at break at 150℃of the substrate can be measured by the following methods, respectively. First, a substrate was cut into a rectangular shape having a length of 150mm and a width of 10mm, and a tensile test was performed on the sample using a tensile tester (Tensilon RTG-1310 manufactured by A & D, co., ltd.) with an initial tension-chuck pitch of 50mm and a tensile speed of 200 mm/min. Measurement the above samples were mounted in a constant temperature layer set at 150℃in advance, and after preheating for 90 seconds, a tensile test was performed. The load applied to the sample when the sample was elongated by 100% (when the chuck pitch was 100 mm) was read, and the value obtained by dividing the cross-sectional area of the sample before the test (substrate thickness×10mm) was taken as the stress at 100% elongation. The elongation at break of the sample was determined as the elongation at break by the above measurement. Each of the measurements was performed 5 times, and the average value was used for evaluation.

The heat shrinkage of the base material at 150 ℃ is preferably 25% or less, more preferably 15% or less, and even more preferably 5% or less. When the thermal shrinkage ratio of the base material is set within the above range, the base material is less likely to shrink due to the temperature of the annealing atmosphere when the resin film is annealed in a state where the adhesive film is bonded, and the adhesive film can be prevented from being peeled off from the resin film before irradiation with active energy rays. In addition, the removal of residual stress and the elimination of deformation of the resin film, which are hindered by the thermal shrinkage of the base material, can be prevented.

The heat shrinkage of the above substrate at 150℃was measured as follows. First, a length direction and a width direction of a base material cut into a square having an outer shape of 120mm×120mm were added to a length direction and a width direction for measuring a distance between standard lines (L ₀ And T ₀ ) Is used to measure the distance between the wires. Next, the above-mentioned base material was left standing at 150 ℃ for 30 minutes, and the distance between the graticules (L and T) in the longitudinal direction and the width direction was measured again at 23 ℃ and 50% rh, and the heat shrinkage was calculated by the following calculation formula.

Heat shrinkage in the longitudinal direction= [ (L) ₀ -L)/L ₀ ]X100 (unit:%)

Heat shrinkage in the width direction= [ (T) ₀ -T)/T ₀ ]X100 (unit:%)

(L ₀ And T ₀ : distance between graticules (mm) before test

L and T: distance between heated reticles (mm)

The thickness of the base material is not particularly limited, but is preferably 12 μm or more and 250 μm or less, more preferably 25 μm or more and 100 μm or less, and still more preferably 38 μm or more and 75 μm or less. By setting the thickness of the base material to the above range, the peeling resistance, the following property, and the peeling property after irradiation with active energy rays in a high-temperature environment such as annealing treatment of the adherend can be made good.

[ Release liner ]

The pressure-sensitive adhesive film of the present invention may have a release liner on the surface of the pressure-sensitive adhesive layer opposite to the substrate. The release liner is not particularly limited. Examples of the release liner include release liners obtained by subjecting at least one surface of a substrate such as a polyethylene film, a polypropylene film, a polyester film, a resin film such as a paper, a nonwoven fabric, a cloth, a foam sheet, a metal foil, or a laminate thereof to a release treatment such as a silicone-based treatment, a long-chain alkyl-based treatment, or a fluorine-based treatment for improving the releasability of a release adhesive.

[ adhesive film ]

The pressure-sensitive adhesive film of the present invention may be a single-sided pressure-sensitive adhesive film having a pressure-sensitive adhesive layer on at least one side of a substrate, or may be a double-sided pressure-sensitive adhesive film having a pressure-sensitive adhesive layer on both sides of a substrate. Among them, a single-sided adhesive film having an adhesive layer on one side of a substrate is preferable from the viewpoint of functioning as a process film or a protective film.

In the case where the adhesive film of the present invention is a double-sided adhesive film, the adhesive layer exhibiting a specific tan δ may be provided on at least one side of the substrate, or the adhesive layers exhibiting a specific tan δ may be provided on both sides of the substrate.

The thickness of the adhesive film of the present invention is not particularly limited, and is preferably an appropriate thickness from the viewpoint of stable processability in the annealing process and the thermoforming process. Specifically, the total thickness of the adhesive film of the present invention is preferably 200 μm or less, more preferably 175 μm or less. The lower limit of the total thickness of the adhesive film of the present invention is not particularly limited, but is preferably 40 μm or more, more preferably 50 μm or more. The total thickness of the adhesive film does not include the thickness of the release liner.

In the adhesive film of the present invention, each of the adhesive layer and the substrate constituting the adhesive film preferably has transparency so that active energy rays can be transmitted sufficiently, and the substrate of the adhesive film may or may not have transparency in the case where the resin film bonded to the adhesive film has transparency and the adhesive film can be irradiated with active energy rays from the resin film side.

[ method for producing adhesive film ]

The adhesive film of the present invention can be produced, for example, by applying an adhesive composition for forming an adhesive layer to at least one surface of a substrate using an applicator, roll coater, gravure coater, reverse coater, spray coater, air knife coater, die coater, or the like, and drying the same.

The adhesive film of the present invention can be produced by the following transfer method: the release liner is coated with an adhesive composition on the surface thereof using a blade coater, roll coater, die coater or the like, and then dried to form an adhesive layer, which is then bonded to at least one surface of a substrate.

In the case of applying the adhesive composition, the viscosity is adjusted by dissolving or dispersing the adhesive composition in an organic solvent in order to obtain good coating workability and the like. Examples of the solvent include toluene, xylene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, and hexane. In addition, in the case of producing a water-based adhesive, water or an aqueous solvent mainly composed of water can be used.

The pressure-sensitive adhesive layer is preferably formed by drying a coating film of the pressure-sensitive adhesive composition at 50 to 140 ℃ for 30 seconds to 10 minutes. In addition, from the viewpoint of accelerating the curing reaction after drying, the coating film of the above adhesive may be dried and then further cured at 30 to 50 ℃.

[ use ]

The adhesive film of the present invention can be preferably used as a process film for temporarily fixing and carrying a resin film, and as a surface protective film for protecting the surface of the resin film. The resin film generally requires annealing treatment, but the adhesive film of the present invention can be used for transportation and surface protection purposes for resin films that do not require annealing treatment.

The resin constituting the resin film is not particularly limited and may be appropriately selected depending on the application and function of the resin film, and examples thereof include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefin resins such as Polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methylpentene and ethylene-propylene copolymer, resins such as acrylic resins, polycarbonates, polyamides, polyimides, triacetylcellulose (TAC) and cycloolefin polymers. In the laminate, the resin film is preferably a resin film before the annealing treatment, but may be a resin film after the annealing treatment.

The glass transition temperature of the resin film is not particularly limited as long as it is a temperature at which annealing treatment can be performed in a temperature range described later, and can be appropriately set according to the type of resin. The other physical properties of the resin film are not particularly limited, and can be appropriately set according to the type of resin.

Examples of the resin film include industrial films used for applications such as display components, electronic components, and vehicle-mounted components. Among them, the above resin film is preferably an optical film because the surface protection and conveyance can be performed by the bonded adhesive film, and the high dimensional accuracy and optical performance required for the optical film can be achieved by the annealing treatment. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an antiglare (antiglare) film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, a brightness enhancement film, a diffusion plate, and a prism sheet.

The pressure-sensitive adhesive film of the present invention can be suitably used as a film for a process and a surface protective film to be bonded to a resin film as described above, but is not limited to this, and can be used as a film for a process and a surface protective film for a member other than a resin film.

[ method of Using adhesive film ]

Examples of the method for using the adhesive film of the present invention include a method for using an adhesive film having the following steps in order: a step of laminating a resin film on an adhesive layer of an adhesive film of the present invention to obtain a laminate, a step of annealing the resin film of the laminate, and a step of irradiating the laminate after the annealing step with active energy rays to peel the adhesive film from the resin film.

In the laminate, the resin film is preferably directly bonded to the pressure-sensitive adhesive layer.

The annealing environment of the resin film can be set appropriately according to the type and material of the resin film, and is preferably at least 70 ℃ and at most 350 ℃, more preferably at least 70 ℃ and at most 150 ℃, and even more preferably at least 70 ℃ and at most 100 ℃. The annealing time is not particularly limited as long as the deformation of the resin film can be eliminated, and may be set to 5 minutes to 1 hour, preferably 10 minutes to 40 minutes.

When the active energy ray is irradiated to the laminate having the resin film bonded to the adhesive layer of the adhesive film, the surface of the laminate on the resin film side may be irradiated, or the surface opposite to the resin film may be irradiated.

The irradiation conditions for irradiation with active energy rays can be appropriately set according to the composition of the adhesive layer, and for example, the illuminance is preferably 50mW/cm ² Above and 2000mW/cm ² The light quantity was 50mJ/cm ² Above and 3000mJ/cm ² The following is given. The light source can be appropriately selected according to the type of active energy ray.

2. Laminate body

The laminate of the present invention includes the adhesive film described in the column "1. Adhesive film" and a resin film provided on the adhesive layer of the adhesive film.

Fig. 2 is a schematic cross-sectional view showing an example of the laminate of the present invention, in which a resin film 11 is provided on the adhesive layer 2 of the adhesive film 10. The resin film is provided in the laminate so as to be in direct contact with (bonded to) the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film.

The adhesive film bonded to the resin film of the laminate of the present invention has an adhesive layer having a temperature range of 0.8 or more in terms of loss tangent tan delta in the range of 70 to 100 ℃ and can be peeled off by irradiation with active energy rays. Therefore, the laminate can be annealed as it is, and the resin film can be surface-protected and transported.

The details of the adhesive film in the laminate of the present invention are the same as those described in the column "1. Adhesive film [ use ]", and therefore, the description thereof is omitted here. In addition, as the resin film in the laminate of the present invention, the resin film described in the column "1. Adhesive film" can be used, and among them, the resin film is preferably an optical film because high dimensional accuracy is required.

3. Method for producing optical film

The method for producing an optical film of the present invention comprises the following steps in order: a step of obtaining a laminate by providing an optical film on an adhesive layer of an adhesive film having the adhesive layer on one surface of a substrate; annealing the optical film of the laminate; and a step of irradiating the laminate after the annealing step with active energy rays to peel the optical film from the adhesive film, wherein the adhesive layer has a temperature range in which the loss tangent tan delta is 0.8 or more in a range of 70 to 100 ℃.

The adhesive film described in the column "1. Adhesive film" can be used as the adhesive film in the method for producing an optical film. The details of the optical film and the adhesive film in the method for producing an optical film, the conditions of the annealing treatment environment, the irradiation surface and the irradiation conditions when the adhesive film is irradiated with active energy rays can be the same as those described in the column of "1. Adhesive film".

The present invention is not limited to the above embodiments. The above-described embodiments are examples, and the present invention is not limited to the above-described embodiments, and any of the above-described embodiments has a configuration substantially similar to the technical idea described in the present invention, and exhibits the same operational effects.

Examples (example)

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The heat shrinkage in the longitudinal direction and the width direction of the polyethylene terephthalate films used in examples and comparative examples were measured at 150℃according to the method described in column "1. Adhesive film". The stress at 100% elongation and elongation at break were measured at 150℃according to the method described in column "1. Adhesive film" above.

Preparation example 1

100 parts by weight of ethyl acetate, 10 parts by weight of toluene, and 0.03 parts by weight of Azobisisobutyronitrile (AIBN) were charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet pipe, and a thermometer, and the mixture was heated to 95 ℃ with stirring and refluxed. 100 parts by weight of n-butyl acrylate, 38 parts by weight of methyl methacrylate and 3.8 parts by weight of methacrylic acid were previously mixed, and the whole of the mixed monomer was added dropwise over a period of 2 hours. After completion of the dropwise addition for 1 hour, 0.03 parts by weight of Azobisisobutyronitrile (AIBN) and 4 parts by weight of toluene were charged and reacted for 2 hours, and the mixture was filtered through a 200-mesh metal wire, whereby a solution (nonvolatile matter: 50 mass%) of an acrylic copolymer (A-1) having a weight average molecular weight of 38 ten thousand was obtained.

Preparation example 2

146 parts by weight of ethyl acetate, 15 parts by weight of toluene, and 0.04 parts by weight of Azobisisobutyronitrile (AIBN) were charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and the mixture was heated to 95 ℃ while stirring and refluxed. 100 parts by weight of methyl acrylate and 61 parts by weight of 2-ethylhexyl acrylate were previously mixed, and the whole of the mixed monomer was added dropwise over a period of 2 hours. After completion of the dropwise addition for 1 hour, 0.04 parts by weight of Azobisisobutyronitrile (AIBN) and 6 parts by weight of toluene were charged and reacted for 2 hours, and the mixture was filtered through a 200-mesh metal wire, whereby a 25-ten-thousand-weight-average-molecular-weight acrylic copolymer (A-2) solution (nonvolatile matter: 50 mass%) was obtained.

Comparative preparation example 1

146 parts by weight of ethyl acetate, 15 parts by weight of toluene, and 0.04 parts by weight of Azobisisobutyronitrile (AIBN) were charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and the mixture was heated to 95 ℃ while stirring and refluxed. 100 parts by weight of methyl acrylate and 61 parts by weight of 2-ethylhexyl acrylate were previously mixed, and the whole of the mixed monomer was added dropwise over a period of 2 hours. After completion of the dropwise addition for 1 hour, 0.04 parts by weight of Azobisisobutyronitrile (AIBN) and 6 parts by weight of toluene were charged and reacted for 2 hours, and the mixture was filtered through a 200-mesh metal wire, whereby a 25-ten-thousand-weight-average-molecular-weight acrylic copolymer (B-1) solution (nonvolatile matter: 50 mass%) was obtained.

Comparative preparation example 2

138 parts by weight of ethyl acetate, 14 parts by weight of toluene, and 0.04 parts by weight of Azobisisobutyronitrile (AIBN) were charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and the mixture was heated to 95 ℃ while stirring and refluxed. 100 parts by weight of n-butyl acrylate and 52 parts by weight of methyl acrylate were mixed in advance, and the whole of the mixed monomer was added dropwise over 2 hours. After completion of the dropwise addition for 1 hour, 0.04 parts by weight of Azobisisobutyronitrile (AIBN) and 6 parts by weight of toluene were added and reacted for 2 hours, and the mixture was filtered through a 200-mesh metal mesh, whereby a 15-ten-thousand-weight acrylic copolymer (B-2) solution (nonvolatile matter: 50 mass%) was obtained.

Comparative preparation example 3

Into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, 82 parts by weight of 2-ethylhexyl acrylate, 14 parts by weight of methyl acrylate, 4 parts by weight of 2-hydroxyethyl acrylate and 200 parts by weight of ethyl acetate were charged, and after stirring at 72℃for 4 hours, the mixture was stirred at 75℃for 5 hours. Next, 2 parts by weight (solid content 0.1 mass%) of Azobisisobutyronitrile (AIBN) solution dissolved in ethyl acetate in advance was added to the above mixture, and after stirring at 72 ℃ for 4 hours, stirring at 75 ℃ for 5 hours. Then, ethyl acetate was added to the mixture and mixed uniformly, and the mixture was filtered through a 200-mesh metal gauze, whereby an acrylic copolymer (B-3) solution (nonvolatile matter 34 mass%) having a weight average molecular weight of 88 ten thousand was obtained.

[ Synthesis of active energy ray-polymerizable Compound (C) ]

A reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer was charged with 7.1 parts by weight of isophorone diisocyanate, 100 parts by weight of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value 48 mgKOH/g), 0.06 parts by weight of 2, 6-di-t-butylcresol as a polymerization inhibitor, and 0.02 parts by weight of dibutyltin dilaurate as a reaction catalyst, and the reaction was terminated at 60℃until the residual isocyanate groups became 0.3% or less, to obtain an ethylenically unsaturated compound (urethane (meth) acrylate) as an active energy ray polymerizable compound. The number of unsaturated groups of the resulting ethylenically unsaturated compound was 10 per 1 molecule.

Example 1

100 parts by weight of the above-mentioned acrylic copolymer (A-1) solution, 50 parts by weight of the active energy ray-polymerizable compound (C), 1 part by weight of 1-hydroxycyclohexyl phenyl ketone (Omurad 184: manufactured by IGM Resins B.V. Co.) as a photopolymerization initiator (D), and an adduct of toluene diisocyanate and trimethylolpropane (hereinafter abbreviated as "BURNOCKD-40" manufactured by DIC Co., ltd.) having a gel fraction of 25% by mass as a crosslinking agent (E) were placed in a light-shielding container equipped with a stirrer, and stirred and mixed for 2 hours to dissolve the resultant mixture, to thereby obtain an adhesive composition (P-1).

The pressure-sensitive adhesive composition (P-1) obtained above was applied to the release treated surface of a release liner (a 50 μm thick polyethylene terephthalate film obtained by release treatment on one side) so that the thickness of the dried pressure-sensitive adhesive layer became 50 μm, and dried at 85℃for 5 minutes, thereby producing a pressure-sensitive adhesive layer having a thickness of 50. Mu.m.

Next, an adhesive layer of the thickness of 50 μm was attached to one side of a polyethylene terephthalate film (a thermal shrinkage in the longitudinal direction of 1.5%, a thermal shrinkage in the width direction of 0.9%, a stress at 100% elongation in the longitudinal direction of 20MPa, and an elongation at break in the longitudinal direction of 235%) having a thickness of 75 μm at 23 ℃ and laminated on the upper surface of the release liner by a roll of 5kg/cm by wire pressing.

Then, the resultant film was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-1) having a thickness of 125. Mu.m.

Example 2

The pressure-sensitive adhesive composition (P-1) obtained above was applied to the release treated surface of a release liner (a polyethylene terephthalate film having a thickness of 50. Mu.m, which was obtained by subjecting one side to release treatment) so that the thickness of the dried pressure-sensitive adhesive layer became 25. Mu.m, and dried at 85℃for 5 minutes, whereby a pressure-sensitive adhesive layer having a thickness of 25. Mu.m was produced.

Next, an adhesive layer of the above-mentioned thickness of 25 μm was attached to one side of a polyethylene terephthalate film (having a heat shrinkage in the longitudinal direction of 1.5%, a heat shrinkage in the width direction of 0.9%, a stress at 100% elongation in the longitudinal direction of 20MPa, and an elongation at break in the longitudinal direction of 235%) having a thickness of 75 μm at 23 ℃ and laminated on the upper surface of the release liner by a roll having a linear pressure of 5 kg/cm.

Then, the resultant was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-2) having a thickness of 100. Mu.m.

Example 3

An adhesive composition (P-2) was obtained in the same manner as in example 1, except that the acrylic copolymer (A-1) solution of example 1 was changed to the acrylic copolymer (A-2) solution and the crosslinking agent (E) was blended so that the gel fraction became 15 mass%.

The release treated surface of the release liner (polyethylene terephthalate film having a thickness of 50 μm obtained by the release treatment on one side) was coated with the adhesive composition (P-2) obtained above so that the thickness of the dried adhesive layer became 50 μm, and dried at 85 ℃ for 5 minutes, thereby producing an adhesive layer having a thickness of 50 μm.

Then, the resultant film was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-3) having a thickness of 125. Mu.m.

Example 4

An adhesive composition (P-3) was obtained in the same manner as in example 1, except that the crosslinking agent (E) was blended in the acrylic copolymer (A-1) solution of example 1 so that the gel fraction became 35 mass%.

The release treated surface of the release liner (polyethylene terephthalate film having a thickness of 50 μm obtained by the release treatment on one side) was coated with the adhesive composition (P-3) obtained above so that the thickness of the dried adhesive layer became 50 μm, and dried at 85 ℃ for 5 minutes, thereby producing an adhesive layer having a thickness of 50 μm.

Then, the resultant film was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-4) having a thickness of 125. Mu.m.

Example 5

An adhesive composition (P-4) was obtained in the same manner as in example 1, except that the crosslinking agent (E) was blended in the acrylic copolymer (A-1) solution of example 1 so that the gel fraction became 40 mass%.

The release treated surface of the release liner (50 μm thick polyethylene terephthalate film obtained by the release treatment on one side) was coated with the adhesive composition (P-4) obtained above so that the thickness of the dried adhesive layer was 50 μm, and dried at 85℃for 5 minutes, thereby producing an adhesive layer having a thickness of 50. Mu.m.

Then, the resultant film was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-5) having a thickness of 125. Mu.m.

Example 6

The release treated surface of the release liner (polyethylene terephthalate film having a thickness of 50 μm obtained by the release treatment on one side) was coated with the adhesive composition (P-1) so that the thickness of the dried adhesive layer became 50 μm, and dried at 85 ℃ for 5 minutes, thereby producing an adhesive layer having a thickness of 50 μm.

Next, an adhesive layer of the thickness of 50 μm was attached to one side of a polyethylene terephthalate film (a thermal shrinkage in the longitudinal direction of 1.5%, a thermal shrinkage in the width direction of 0.9%, a stress at 100% elongation in the longitudinal direction of 37MPa, and an elongation at break in the longitudinal direction of 231%) having a thickness of 75 μm at 23 ℃ and laminated by a roll of 5kg/cm wire-pressing from the upper surface of the release liner.

Then, the resultant film was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-6) having a thickness of 125. Mu.m.

Example 7

Next, an adhesive layer of the thickness of 50 μm was attached to one side of a polyethylene terephthalate film (0.4% in the longitudinal direction, 0.0% in the width direction, 70MPa in the longitudinal direction, 266% in the elongation at break in the longitudinal direction) having a thickness of 50 μm at 23 ℃.

Then, the resultant was cured at 40℃for 48 hours, thereby obtaining an adhesive film (T-7) having a thickness of 100. Mu.m.

Comparative example 1

An adhesive composition (Q-1) was obtained in the same manner as in example 1, except that the acrylic copolymer (A-1) solution of example 1 was changed to the acrylic copolymer (B-1) solution, and the crosslinking agent (E) was blended so that the gel fraction became 30 mass%.

The release treated surface of the release liner (polyethylene terephthalate film having a thickness of 50 μm obtained by the release treatment on one side) was coated with the adhesive composition (Q-1) obtained above so that the thickness of the dried adhesive layer became 50 μm, and dried at 85 ℃ for 5 minutes, thereby producing an adhesive layer having a thickness of 50 μm.

Then, the resultant was cured at 40℃for 48 hours, thereby obtaining an adhesive film (U-1) having a thickness of 125. Mu.m.

Comparative example 2

An adhesive composition (Q-2) was obtained in the same manner as in example 1 except that the acrylic copolymer (A-1) solution of example 1 was changed to the acrylic copolymer (B-2) solution and the crosslinking agent (E) was blended so that the gel fraction became 50 mass%.

The release treated surface of the release liner (50 μm thick polyethylene terephthalate film obtained by the release treatment on one side) was coated with the adhesive composition (Q-2) obtained above so that the thickness of the dried adhesive layer was 50 μm, and dried at 85 ℃ for 5 minutes, thereby producing an adhesive layer having a thickness of 50 μm.

Then, the resultant was cured at 40℃for 48 hours, thereby obtaining an adhesive film (U-2) having a thickness of 125. Mu.m.

Comparative example 3

D-40 was blended in the acrylic copolymer (B-3) solution so that the gel fraction became 80 mass%, to obtain an adhesive composition (Q-3). The adhesive composition (Q-3) had a composition containing no active energy ray-curable compound, and had the same adhesion and releasability before and after irradiation with active energy rays.

The release treated surface of the release liner (50 μm thick polyethylene terephthalate film obtained by the release treatment on one side) was coated with the adhesive composition (Q-3) obtained above so that the thickness of the dried adhesive layer became 5 μm, and dried at 85 ℃ for 5 minutes, thereby producing an adhesive layer having a thickness of 5 μm.

Next, an adhesive layer of the thickness of 5 μm was attached to one side of a polyethylene terephthalate film (a heat shrinkage in the longitudinal direction of 1.5%, a heat shrinkage in the width direction of 0.9%, a stress at 100% elongation in the longitudinal direction of 20MPa, and an elongation at break in the longitudinal direction of 235%) having a thickness of 75 μm at 23 ℃ and laminated by a roll of 5kg/cm wire-pressing from the upper surface of the release liner.

Then, the resultant was cured at 40℃for 48 hours, thereby obtaining an adhesive film (U-3) having a thickness of 55. Mu.m.

Comparative example 4

The release treated surface of the release liner (50 μm thick polyethylene terephthalate film obtained by the release treatment on one side) was coated with the adhesive composition (Q-3) so that the thickness of the dried adhesive layer became 5 μm, and dried at 85℃for 5 minutes, thereby producing an adhesive layer having a thickness of 5. Mu.m.

Next, an adhesive layer of the thickness of 5 μm was attached to one side of a polyethylene terephthalate film (0.4% in the longitudinal direction, 0.0% in the width direction, 37MPa in the longitudinal direction, and 266% in the elongation at break in the longitudinal direction) having a thickness of 50 μm at 23 ℃.

Then, the resultant was cured at 40℃for 48 hours, thereby obtaining an adhesive film (U-4) having a thickness of 55. Mu.m.

< evaluation >

The following evaluation was performed on the adhesive films obtained in examples and comparative examples. The results of the evaluations are shown in tables 1 to 3. The optical film (resin film) used in the 180 ° peel adhesion and curl test in the following evaluation was a polyethylene terephthalate film for optical use (manufactured by eastern co., product name "lumirro 100U46", glass transition temperature 120 ℃ C., thickness 100 μm). The optical film (resin film) used in the thermoforming test was an acrylic resin film for optical use (manufactured by Mitsubishi chemical corporation, product name "ACRYPLENHBA7007P", glass transition temperature 92℃and thickness 75 μm).

[ measurement of loss tangent (tan. Delta.) of adhesive layer ]

Each of the adhesive compositions obtained above was applied to the surface of a release liner, and heated at 85℃for 5 minutes using an oven to prepare an adhesive layer having a thickness of 50. Mu.m, and the obtained adhesive layers were superimposed to prepare an adhesive layer having a thickness of 2 mm. Next, the adhesive layer was cut into a round shape with a diameter of 8mm as a test piece. Then, the test piece was sandwiched between parallel disks, which are measuring parts of a viscoelasticity tester (trade name: ares2 KSTD), and storage modulus (G ') and loss modulus (G') were measured at a temperature ranging from-40 ℃ to 150 ℃ under a temperature rising rate of 2.0 ℃/min and a frequency of 1Hz in a shear stress measurement mode, and loss tangent (tan delta) was calculated from the G ', G', using a viscoelasticity tester (manufactured by Rheometrics). The results are shown in the tables described below.

[ 180℃peel adhesion of adhesive film ]

The 180 ° peel adhesion of the adhesive films of examples and comparative examples was measured by the following method. The results are shown in tables 2 to 3.

(1) The adhesive film was attached to the optical film at 23℃and 50% RH by reciprocating and once pressing with a 2kg roller.

(2) After standing at 23℃and 50% RH for 1 hour, the adhesive film was peeled off from the optical film at a stretching speed of 300 mm/min at 23℃and 50% RH in a direction of 180 degrees, and the strength (unit: N/25 mm) at this time was measured.

Easy peelability: 180 DEG peel adhesion of adhesive film after active energy ray irradiation

The 180 ° peel adhesion of the adhesive films of examples and comparative examples after irradiation with active energy rays was measured by the following method. The results are shown in tables 2 to 3.

(2) After standing at 23℃and 50% RH for 1 hour, annealing treatment was performed by heating at 90℃for 20 minutes. Ultraviolet irradiation (cumulative irradiation amount 180 mJ/cm) was performed from a height of 8cm at a conveying speed of 6.5 m/min using an electrodeless lamp of Heraeus Co., ltd. Of 90mW ² )。

(3) The adhesive film was peeled off from the optical film at a stretching speed of 300 mm/min at 23℃and 50% RH in a direction of 180 degrees, and the strength (unit: N/25 mm) at this time was measured.

(4) The peelability was evaluated visually. The evaluation criteria are shown below.

(reference)

And (3) the following materials: the adhesive film can be peeled off without deformation and destruction of the optical film.

O: the adhesive film can be peeled off without deformation or damage of the optical film.

X: cannot be peeled off and the optical film is destroyed.

-: since the active energy ray-curable compound was not contained, no change in physical properties due to irradiation with active energy rays was confirmed.

(5) The residual gum was visually evaluated. The evaluation criteria are shown below.

(reference)

And (2) the following steps: there is no adhesive residue.

X: residues of the adhesive remain on the optical film.

[ performance of eliminating residual stress and deformation of the resin film during annealing treatment was not hindered: curl test ]

In order to evaluate the performance of eliminating the residual stress and deformation of the resin film during the annealing treatment, the curl test of the optical film bonded with the adhesive films of examples and comparative examples was performed by the following method. FIG. 3 is an explanatory view for explaining a curl test method. The results are shown in tables 2 to 3.

(1) The adhesive layer side surface of the adhesive film was attached to one surface of the optical film at 23℃and 50% RH, and the film was cut into 150mm square pieces to prepare a sample 20 (laminate 20).

(2) The sample 20 was placed on the horizontal surface 30 with the surface 20a on the optical film side facing downward, and the floating distances (L1) of the four corners of the sample 20 with respect to the horizontal surface 30 were measured at 23 ℃ and 50% rh, respectively (see fig. 3 (a)).

(3) Then, the above sample 20 was heated in an oven at 90 ℃ for 20 minutes to anneal the optical film, and then left at room temperature to return the annealed sample 20' to room temperature.

(4) The annealed sample 20' was placed on the horizontal surface 30 with the surface 20' a on the optical film side facing downward, and the floating distances (L2) of the four corners of the sample 20' with respect to the horizontal surface 30 were measured at 23 ℃ and 50% rh, respectively (see fig. 3 (b)). As shown in fig. 3 (c), when the annealed sample 20' is bent with the optical film side surface 20' a as the inner surface, the adhesive film side surface 20' b of the sample 20' is arranged so as to be in contact with the horizontal surface 30, and the length from the horizontal surface 30 to the four corners of the sample 20' is expressed as a negative value as the floating distance (L2).

(5) The floating distance Δ (L) of each corner is calculated by the following calculation formula.

Distance delta (L) =distance after heating (L2) -distance before heating (L1)

It should be noted that,

(6) The average value is calculated from the respective deltas (L) at the four corners, and the calculated average value is used as the floating distance ave delta (L) of the adherend. The deformation adaptability is judged according to the floating distance ave delta (L) of the adhered object. The deformation suitability is determined by the following criteria. For reasons described later, the smaller the absolute value of the floating distance aveΔ (L), the more the residual stress and deformation of the resin film are eliminated.

(reference)

And (3) the following materials: -5mm < the float distance aveDeltaL < 5mm

And (2) the following steps: the floating distance aveDeltaL is less than or equal to-5 mm and less than or equal to-9 mm, and the floating distance aveDeltaL is less than or equal to 5mm and less than or equal to 9mm

X: the floating distance ave delta (L) is less than or equal to-9 mm, and 9mm is less than or equal to the floating distance ave delta (L)

[ forming stability: thermoforming test ]

In order to evaluate the ease of following the processing shape when the optical film was thermoformed into a curved shape, a thermoforming test of the optical film to which the adhesive films of examples and comparative examples were bonded was performed by the following method. Fig. 4 is an explanatory diagram illustrating a thermoforming test method. The results are shown in tables 2 to 3.

(1) A spring 42 is provided in the center of a rectangular metal plate 41 having a thickness of 8mm and 50X 130mm, and an iron ball 43 having a diameter of 20mm is fixed to the spring 42. Further, a metal tube 44 is provided in the center of the metal plate 41 so that the spring 42 is positioned inside. A rectangular metal plate 45 having a hole of 25mm diameter and a thickness of 4mm and 50×130mm is provided in the center portion of the cylinder 44, and the spring 42 and the iron ball 43 are protruded from the hole of the metal plate 45 (see fig. 4).

(2) The pressure-sensitive adhesive layer side surface of the pressure-sensitive adhesive film was attached to one surface of an optical film, and the film was cut into 50mm×60mm pieces to prepare a sample 46 (laminate 46). A rectangular metal plate 47 having a hole of 25mm diameter and a thickness of 25mm and 50X 100mm was formed in the center portion, and the sample 46 was fixed so as to cover the hole in the center portion. At this time, the optical film surface 46a of the sample 46 is fixed so as to be in contact with the metal plate 47. (see FIG. 5).

(3) The metal plate 47 to which the sample 46 is fixed is overlapped on the metal plate 45. At this time, the hole formed in the center of the metal plate 45 overlaps with the hole formed in the center of the metal plate 47. Further, a weight 48 of 2kg was provided on the metal plate 47, and the metal plate 47 was fixed (see fig. 6). Thereby, the iron ball 43 is pushed into the sample 46 from the substrate surface 46b of the sample 46, thereby stretching the sample 46 into a curved shape. At this time, the spring 42 is adjusted by the iron ball 43 so as to apply a force of 12N to the sample 46. The entire test jig manufactured in the above-described step was used as the test jig 40.

(4) The test jig 40 was heated in an oven at 90 ℃ for 20 minutes to perform a thermoforming test.

(5) The test fixture 40 after the thermoforming test was removed from the oven and left at room temperature, allowing the sample 46 to return to room temperature. The appearance of the sample 46 was visually observed, and the molding stability was evaluated according to the following criteria. The less wrinkles in the sample 46 stretched by thermoforming indicates the more excellent forming stability.

(reference)

And (2) the following steps: the sample after the test had no wrinkles or had wrinkles in the peripheral portion of the bent portion by stretching, but had no wrinkles in the stretched and bent portion.

X: the stretch-bent portion is pleated.

[ Table 1 ]

[ Table 2 ]

[ Table 3 ]

From the above results, it can be seen that: the adhesive films of examples 1 to 7 suppressed the occurrence of curling of the optical film in the curl test, whereas the adhesive films of comparative examples 1 to 4 mostly caused curling of the optical film in the curl test. These results indicate that the adhesive film of the present invention does not easily interfere with the elimination of residual stress and deformation of the resin film caused by annealing at a temperature of about 100 ℃.

The relationship between the results of the curl test and the performance of eliminating residual stress and deformation of the resin film during the annealing treatment is shown below. That is, if the annealing treatment of the resin film is performed in a state where the adhesive film is bonded to the resin film, thermal shrinkage of the resin film (optical film) occurs in a state where the bonded state is maintained. At this time, the adhesive layers of the adhesive films bonded to the resin films were deformed, and it was estimated that the adhesive films of examples 1 to 7 exhibited flexibility and fluidity in an annealing treatment environment by satisfying specific physical properties (tan δ) of the adhesive layers, and the deformation generated inside the layers could be dissipated. As a result, curling is not easily generated in the shrinkage direction, and therefore, it can be presumed that the absolute value of aveΔ (L) becomes smaller in the curl test. It can be said that the adhesive layer capable of dissipating the deformation generated inside the layer does not interfere with the deformation accompanying the elimination of the residual stress and deformation of the resin film at the time of the annealing treatment, and therefore the residual stress and deformation of the resin film can be sufficiently eliminated even in the bonded state of the adhesive film and the resin film. On the other hand, since the pressure-sensitive adhesive layers of the pressure-sensitive adhesive films of comparative examples 1 to 4 do not satisfy specific physical properties, the deformation of the pressure-sensitive adhesive layers is kept inside and curling occurs in the shrinkage direction, and therefore, it can be estimated that the absolute value of aveΔ (L) increases in the curling test. The adhesive layer which retains the deformation generated inside the layer restricts deformation associated with the elimination of residual stress and deformation of the resin film generated during the annealing treatment. Therefore, it can be said that the residual stress and strain in the resin film are not sufficiently eliminated.

The adhesive films of examples 1 to 7 exhibited high adhesion before irradiation with active energy rays, and after annealing treatment of the resin film (optical film), the adhesion was greatly reduced by irradiation with active energy rays, and the adhesive films exhibited easy peelability without adhesive residue.

In examples 1 to 7, the adhesive films of examples 1 to 6 sufficiently follow the curved processing shape in the thermoforming test, and the occurrence of wrinkles was suppressed, so that the adhesive films showed molding stability.

Symbol description

1 … substrate, 2 … adhesive layer, 10 … adhesive film, 11 … resin film, 20 … laminate (sample).

Claims

1. An adhesive film, characterized in that,

the adhesive layer has a temperature range of 0.8 or more in which the loss tangent tan delta at a frequency of 1Hz is in the range of 70-100 ℃,

the adhesive film can be peeled off by irradiation of active energy rays.

2. An adhesive film, characterized in that,

3. The adhesive film according to claim 1 or 2, wherein the adhesive layer has a gel fraction of 50 mass% or less.

4. The adhesive film according to claim 1 or 2, wherein the substrate has a value of 100% elongation stress at 150 ℃ of 5MPa to 60MPa.

5. The adhesive film according to claim 1 or 2, wherein the adhesive film is used by being attached to a resin film.

6. Adhesive film according to claim 1 or 2, wherein the adhesive film is for surface protection use.

7. The adhesive film according to claim 1 or 2, wherein the adhesive film is used for a handling process.

8. A laminate body, characterized in that,

the laminate comprises the adhesive film according to any one of claims 1 to 7, and a resin film provided on the adhesive layer of the adhesive film.

9. The laminate according to claim 8, wherein the resin film is an optical film.

10. A method for using an adhesive film is characterized in that,

the use method sequentially comprises the following steps:

a step of bonding a resin film to the adhesive layer of the adhesive film according to any one of claims 1 to 7 to obtain a laminate;

annealing the resin film of the laminate; and