KR20230167423A - Subject matter for adhesives, adhesive compositions and adhesive films - Google Patents

Abstract

The purpose of the present disclosure is to provide a base material for an adhesive for producing an adhesive film with excellent adhesiveness over a wide temperature range. The base material for an adhesive according to the present disclosure includes an alkyl acrylate (a1) having an alkyl group having 4 to 8 carbon atoms, a (meth)acrylate (a2) having a hydroxyl group, and two alkyl groups each having 1 to 2 carbon atoms. It contains a copolymer (A) containing dialkyl (meth)acrylamide (a3) having as a constituent monomer.

Description

Subject matter for adhesives, adhesive compositions and adhesive films

This disclosure relates to a base material for an adhesive, an adhesive composition, and an adhesive film.

As an acrylic adhesive, a (co)polymer containing a specific alkyl (meth)acrylate as an essential structural unit has been developed (for example, patent document 1).

Japanese Patent Publication No. 2004-143420

The present disclosure aims to provide an adhesive base material for producing an adhesive film with excellent adhesion in a wide temperature range, an adhesive composition containing this adhesive base material, and an adhesive film produced from this adhesive composition.

The base material (B) for an adhesive according to one aspect of the present disclosure includes an alkyl acrylate (a1) having an alkyl group having 4 to 8 carbon atoms, a (meth)acrylate (a2) having a hydroxyl group, and each carbon number being 1. It contains a copolymer (A) containing dialkyl (meth)acrylamide (a3) having two alkyl groups of -2 as a structural unit.

The adhesive composition according to one aspect of the present disclosure contains the adhesive base material (B) and polyfunctional (meth)acrylate (C).

The adhesive film according to one aspect of the present disclosure has a cured layer made of a cured product of the adhesive composition.

Conventionally, natural rubber adhesives or acrylic adhesives are known as adhesives for adhesive tapes or adhesive sheets. As an acrylic adhesive, a (co)polymer containing a specific alkyl (meth)acrylate as an essential structural unit has been developed (for example, Japanese Patent Application Laid-Open No. 2004-143420).

However, according to the inventor's investigation, even the technology of Patent Document 1 was not sufficiently satisfactory for adhesion over a wide temperature range.

Accordingly, the inventor studied to provide a base material for an adhesive for producing an adhesive film with excellent adhesiveness in a wide temperature range, and arrived at the present disclosure.

Hereinafter, one embodiment of the present disclosure will be described. In addition, the following embodiment is only one of various embodiments of the present disclosure. The following embodiments can be modified in various ways depending on the design as long as the purpose of the present disclosure can be achieved.

The base material (B) for an adhesive according to this embodiment includes the residue of an alkyl acrylate (a1) having an alkyl group having 4 to 8 carbon atoms, the residue of (meth)acrylate (a2) having a hydroxyl group, and each of the carbon atoms. It contains a copolymer (A) containing as a structural unit the residue of dialkyl (meth)acrylamide (a3) having two alkyl groups with a value of 1 to 2.

An adhesive film having a cured layer composed of a cured product of adhesive composition (X) containing the adhesive base material (B) of the present embodiment exhibits the following effects.

(1) Under a low-temperature atmosphere, for example, at 5°C, the adhesive strength can be increased when the adhesive film is bonded to an appropriate object, and glue residue is less likely to form when the adhesive film is peeled from the object.

(2) Under a high-temperature atmosphere, for example, at 40°C, the adhesive strength can be increased when the adhesive film is bonded to an object, and when the adhesive film is peeled from the object, it is difficult for glue residue to form.

(3) After bonding an adhesive film to the film of an object having a film made of metal or metal oxide, especially a film made of ITO (indium tin oxide), deterioration of the film is suppressed when the adhesive film is peeled from this film. can do.

(4) The adhesive film has excellent bending resistance.

In addition, the above-mentioned “glue residue” refers to a phenomenon in which the hardened layer is damaged and part of it remains on the object.

<Alkyl acrylate (a1)>

Alkyl acrylate (a1) (hereinafter also referred to as (a1) component) in this embodiment has an alkyl group having 4 to 8 carbon atoms, as described above. Component (a1) contains, for example, at least one member selected from the group consisting of n-butylacrylate, neopentyl acrylate, n-octylacrylate, and 2-ethylhexyl acrylate. From the viewpoint of adhesiveness, component (a1) preferably contains at least one of 2-ethylhexyl acrylate and n-butyl acrylate, and more preferably includes 2-ethylhexyl acrylate and 2-ethylhexyl acrylate. It contains at least one of the combinations of late and n-butylacrylate, and particularly preferably contains 2-ethylhexyl acrylate.

<(meth)acrylate (a2) having a hydroxyl group>

(meth)acrylate (a2) (hereinafter also referred to as component (a2)) having a hydroxyl group in the present disclosure is a (meth)acrylic acid ester having a hydroxyl group and excluding the component (a1) described above. Component (a2) is, for example, (meth)acrylate (a21) (hereinafter also referred to as (a21) component) having a primary hydroxyl group, (meth)acrylate (a22) (hereinafter referred to as (a21) component) having a secondary hydroxyl group, for example a22) component), and (meth)acrylate (a23) having a primary hydroxyl group and a secondary hydroxyl group (hereinafter also referred to as the (a23) component).

And, (meth)acrylate means at least one of methacrylate and acrylate, and (meth)acrylic means at least one of methacrylic and acrylic.

Component (a21) is, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-1-methyl. Ethyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate and 12-hydroxylauryl (meth)acrylate. It contains at least one type selected from the group consisting of rates.

The component (a22) contains, for example, at least one member selected from the group consisting of 2-hydroxypropyl (meth)acrylate and 2-hydroxybutyl (meth)acrylate.

Component (a23) contains, for example, glycerin mono(meth)acrylate.

From the viewpoint of adhesiveness, the component (a2) preferably contains (meth)acrylate having at least a secondary hydroxyl group. That is, it is preferable that component (a2) contains at least one of component (a22) and component (a23), for example. It is more preferable that component (a2) contains component (a22), component (a23), or component (a21) and component (a22). It is especially preferable that the component (a2) contains the component (a23), or the component (a21) and the component (a22).

<Dialkyl (meth)acrylamide (a3)>

Dialkyl (meth)acrylamide (a3) (hereinafter also referred to as (a3) component) in the present disclosure is, for example, selected from the group consisting of dimethyl (meth)acrylamide and diethyl (meth)acrylamide. Contains at least one type.

From the viewpoint of adhesiveness, component (a3) preferably contains at least one of dimethyl acrylate and diethyl acrylamide, and more preferably contains both dimethyl acrylate and diethyl acrylate.

<Copolymer (A)>

The copolymer (A) in the present disclosure contains component (a1), component (a2), and component (a3) as constituent monomers. A constituent monomer is a monomer that constitutes the copolymer (A) by polymerization. That is, copolymer (A) is a polymer of constituent monomers including component (a1), component (a2), and component (a3). In other words, the copolymer (A) contains the residue of component (a1), the residue of component (a2), and the residue of component (a3) as structural units.

The constituent monomers of the copolymer (A) may include only component (a1), component (a2), and component (a3), or may further include monomers other than these. Constituent monomers include monomers other than component (a1), component (a2), and component (a3), for example, monomer (a4) having a carboxyl group (hereinafter also referred to as component (a4)), (a1) It may contain at least one of the monomers (a5) (hereinafter also referred to as (a5) component) other than the component (a2) component, (a3) component, and (a4) component. That is, the copolymer (A) may contain only the residues of component (a1), the residues of component (a2), and the residues of component (a3) as structural units, and the residues of component (a1) and component (a2) may be included as structural units. In addition to the residue and the residue of component (a3), at least one of the residue of component (a4) and the residue of component (a5) may be further included as a structural unit.

Component (a4) is, for example, from the group consisting of monobasic acids such as (meth)acrylic acid and crotonic acid, polybasic acids such as maleic acid, itaconic acid, and fumaric acid, or acid anhydrides thereof, and monoalkyl esters of these polybasic acids. Contains at least one selected type. Component (a4) preferably contains at least one member selected from the group consisting of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid, and more preferably contains acrylic acid.

Component (a5) includes, for example, vinyl esters such as vinyl acetate, vinyl propionate, and vinyl butyrate, and methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and neopentyl methacrylate. , selected from the group consisting of (meth)acrylates such as n-octyl methacrylate, nonyl (meth)acrylate, 2-ethylhexyl methacrylate, decyl (meth)acrylate, and lauryl (meth)acrylate. Contains at least one type of It is preferable that component (a5) contains vinyl acetate from the viewpoint of adhesiveness.

The copolymer (A) in this embodiment is made by polymerizing the constituent monomers including component (a1), component (a2), and component (a3) by a known polymerization method, such as lump polymerization, solution polymerization, emulsion polymerization, Alternatively, it can be synthesized by polymerization, such as suspension polymerization. In this case, known polymerization initiators, such as azo-based polymerization initiators such as azobisisobutyronitrile and azobisisovaleronitrile, or benzoyl peroxide, di-tert-butyl peroxide, lauryl peroxide, etc. The constituent monomers can be polymerized in the presence of a peroxide-based polymerization initiator or the like.

Among the above polymerization methods, solution polymerization is preferred in which constituent monomers are polymerized in the presence of a solvent (S). The solvent (S) contains, for example, at least one selected from the group consisting of acetone, ethyl acetate, etc. Through this solution polymerization, a mixture of the solvent (S) and the copolymer (A) can be obtained. By separating the solvent (S) and copolymer (A) in this mixture, only copolymer (A) can be obtained. In addition, the mixture of this solvent (S) and the copolymer (A) may be used as the base material (B) for an adhesive (B) described later. In addition, the base material (B) for an adhesive can also be prepared by adjusting the content ratio of the solvent (S) in the mixture as necessary and adding appropriate additives to the mixture as needed.

The glass transition temperature (Tg) of the copolymer (A) is preferably -50°C or higher and -30°C or lower, and more preferably -40°C or higher and -30°C or lower from the viewpoint of the balance between bending resistance and adhesiveness.

The glass transition temperature (Tg) is the loss coefficient (tanδ) obtained by measuring the copolymer (A) under the following conditions using a viscoelasticity measuring device (for example, model number MCR-302, manufactured by Anton Paar). The temperature was set to show the peak value.

-Jig: ϕ 8mm parallel plate.

-Sample thickness: 1mm.

-Deformation: 1%.

-Frequency: 1Hz.

-Temperature increase rate: 5℃/min.

-Temperature range: -50℃ to 180℃.

In addition, the above Tg can be adjusted appropriately by selecting the type of each monomer among the constituent monomers of the copolymer (A) and adjusting the weight ratio. For example, among all monomers, the larger the weight ratio of component (a1), the smaller the Tg, and the larger the weight ratio of the (a2) component and (a3) component, the larger the Tg.

The weight average molecular weight (Mw, converted to polystyrene) of the copolymer (A) determined from gel permeation chromatography (GPC) is preferably 300,000 or more and 1,200,000 or less, from the viewpoint of improving adhesion and handling. Preferably it is 400,000 or more and 1,000,000 or less, particularly preferably 500,000 or more and 900,000 or less.

The measurement conditions for gel permeation chromatography (GPC) in this embodiment are as follows.

-Device: “HLC-8120GPC” [manufactured by Tosoh Corporation].

-Columns: “GuardcolumnHXL-H” (1) and “TSKgelGMHXL” (2) (all manufactured by Tosoh Corporation).

-Sample solution: 0.25% by weight tetrahydrofuran solution.

-Solution injection volume: 100μl.

-Flow rate: 1ml/min.

-Measurement temperature: 40℃.

-Detection device: Refractive index detector.

-Reference material: standard polystyrene.

The hydroxyl group concentration of the copolymer (A) is preferably 0.01 mol/kg or more and 1.0 mol/kg or less, more preferably 0.1 mol, from the viewpoint of suppressing deterioration of adhesive strength over time and the balance of adhesiveness. /kg or more and 0.9 mol/kg or less, particularly preferably 0.2 mol/kg or more and 0.8 mol/kg or less. And, the hydroxyl group concentration of the copolymer (A) is the number of moles of hydroxyl groups that the copolymer (A) has per unit weight of the copolymer (A). This hydroxyl group concentration can be calculated by measuring the hydroxyl value (KOHmg/g) of the copolymer (A) in accordance with JIS K0070 and calculating it from the result.

In addition, the molar ratio of primary hydroxyl groups to secondary hydroxyl groups [primary hydroxyl group/secondary hydroxyl group] (β) of the copolymer (A) is preferably 0 from the viewpoint of the balance between suppressing glue residue and improving adhesion. /100 or more and 90/10 or less, more preferably 10/90 or more and 70/30 or less, especially preferably 15/85 or more and 50/50 or less.

This molar ratio (β) can be obtained, for example, from the spectrum obtained by measuring the copolymer (A) by ¹ H-NMR (nuclear magnetic resonance spectroscopy).

In addition, the hydroxyl group concentration and molar ratio (β) of the copolymer (A) can be adjusted, for example, by selecting the type of component (a2) among the constituent monomers of the copolymer (A) and adjusting the weight ratio.

The amide group concentration of the copolymer (A) is preferably 0.01 mol/kg or more and 0.5 mol/kg or less, more preferably 0.1 mol/kg or more and 0.45 mol/kg or less, from the viewpoint of the balance between bending resistance and adhesiveness. Particularly preferably, it is 0.2 mol/kg or more and 0.4 mol/kg or less. And, the amide group concentration of the copolymer (A) is the number of moles of amide groups possessed by the copolymer (A) per unit weight of the copolymer (A). The amide group of copolymer (A) is derived from component (a3). The amide group concentration can be calculated by measuring the proton of the alkyl group bonded to the amide group by ¹ H-MNR, and from the type and weight of component (a3) based on the total weight of the monomers constituting the copolymer (A). there is.

Additionally, the amide group concentration of the copolymer (A) can be adjusted, for example, by selecting the type of component (a3) among the constituent monomers of the copolymer (A) and adjusting the weight ratio.

In addition, the carboxyl group concentration of the copolymer (A) is preferably 0 mol/kg or more and 0.35 mol/kg or less, more preferably 0 mol/kg or more and 0.17 mol/kg or less, especially from the viewpoint of adhesiveness and deterioration suppression. Preferably it is 0.01 mol/kg or more and 0.09 mol/kg or less. And, the carboxyl group concentration of the copolymer (A) is the number of moles of carboxyl groups that the copolymer (A) has per unit weight of the copolymer (A).

The carboxyl group concentration can be calculated, for example, by measuring the acid value (KOH mg/g) of the copolymer (A) in accordance with JIS K0070 and using the results.

The carboxyl group concentration of the copolymer (A) can be adjusted, for example, by selecting the type of component (a4) among the monomers constituting the copolymer (A) and adjusting the weight ratio.

The ratio of the total weight of component (a1), component (a2), and component (a3) to the total weight of the constituent monomers of the copolymer (A) is preferably 70% by weight or more and 100% by weight or less, more preferably. is 80% by weight or more and 98% by weight or less, particularly preferably 85% by weight or more and 95% by weight or less.

In addition, the ratio of component (a1) to the total weight of component (a1), component (a2), and component (a3) in the constituent monomers of copolymer (A) is preferably 75% by weight or more and 97% by weight or less, More preferably, it is 80% by weight or more and 95% by weight or less, and the proportion of component (a2) is preferably 0.5% by weight or more and 15% by weight or less, and more preferably 1% by weight or more and 12% by weight or less, and component (a3) ) The proportion is preferably 1% by weight or more and 10% by weight or less, more preferably 8% by weight or less.

<Material for adhesive (B)>

The base material (B) for an adhesive of this embodiment contains a copolymer (A). The base material (B) for an adhesive is preferable as a base material for the adhesive composition (X) described later.

The base material (B) for an adhesive consists, for example, of only the copolymer (A). Additionally, the base material (B) for an adhesive may contain a copolymer (A) and a solvent (S). The solvent (S) contains, for example, at least one selected from the group consisting of acetone, ethyl acetate, etc., but is not limited to these alone. The proportion of the solvent (S) is preferably 50% by weight or more and 80% by weight or less, more preferably 60% by weight or more and 70% by weight or less, relative to the weight of the base material (B) for the adhesive.

The adhesive base material (B) may, if necessary, contain appropriate additives other than the copolymer (A) and the adhesive base material (B). In addition, it is preferable that the base material (B) for an adhesive does not contain a component having reaction hardening properties.

<Multifunctional (meth)acrylate (C)>

The polyfunctional (meth)acrylate (C) (hereinafter also referred to as (C) component) in this embodiment is a compound having a plurality of (meth)acryloyl groups in the molecule. The (meth)acryloyl group is one or both of acryloyl and methacryloyl groups. Component (C) includes, for example, difunctional (meth)acrylate (C1) having one hydroxyl group, tri- to penta-functional (meth)acrylate (C2) having one hydroxyl group, and tri-functional (meth)acrylate (C2) having no hydroxyl group. It contains at least one type selected from the group consisting of hexafunctional (meth)acrylate (C3).

Bifunctional (meth)acrylate (C1) (hereinafter also referred to as (C1) component) having one hydroxyl group has one hydroxyl group and two (meth)acryloyl groups in the molecule. The (C1) component contains, for example, at least one member selected from the group consisting of glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, and trimethylolethane di(meth)acrylate.

The 3- to 5-functional (meth)acrylate (C2) (hereinafter also referred to as the (C2) component) having one hydroxyl group has one hydroxyl group and 3 to 5 (meth)acryloyl groups in the molecule. (C2) Components include, for example, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate. It contains at least one type selected from the group consisting of.

The 3- to 6-functional (meth)acrylate (C3) (hereinafter also referred to as the (C3) component) that does not have a hydroxyl group does not have a hydroxyl group in the molecule and also has 3 to 6 (meth)acryloyl groups. (C3) Components include, for example, glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipenta. It contains at least one member selected from the group consisting of erythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate.

Component (C) preferably contains component (C3), component (C1) and component (C3), or component (C2) and component (C3), from the viewpoint of stickiness and residue. It is preferable to contain. Component (C) more preferably contains component (C3), and particularly preferably contains trimethylolpropane tri(meth)acrylate.

<Adhesive composition (X)>

The pressure-sensitive adhesive composition (X) of the present embodiment contains a pressure-sensitive adhesive base material (B) containing the copolymer (A) and component (C).

With respect to the total weight of the copolymer (A) and (C) components in the adhesive composition (X), preferably the proportion of the copolymer (A) is 75% by weight or more and 99.9% by weight or less, and the proportion of component (C) is 0.1% by weight or more and 25% by weight or less, more preferably, the proportion of copolymer (A) is 85% by weight or more and 99.7% by weight or less, and the proportion of component (C) is 0.3% by weight or more and 15% by weight or less, especially Preferably, the proportion of copolymer (A) is 95% by weight or more and 99.5% by weight or less, and the proportion of component (C) is 0.5% by weight or more and 5% by weight or less.

The adhesive composition (X) of the present embodiment can be produced, for example, by mixing the adhesive base material (B) containing the copolymer (A) and the component (C).

In addition, the adhesive composition (X) of the present embodiment may further contain additives as needed within a range that does not impair the effect of the present disclosure. The additive contains at least one selected from the group consisting of, for example, a tackifier (N) such as terpene resin and rosin resin, a photopolymerization initiator (D), a plasticizer, a filler, a pigment, an ultraviolet absorber, and an antioxidant. can do.

<Adhesive film>

The adhesive film of this embodiment has a cured layer made of a cured product of adhesive composition (X). The thickness of the cured layer is preferably 10 μm or more and 200 μm or less, and more preferably 20 μm or more and 100 μm or less. The adhesive film, for example, consists of only a cured layer. Additionally, the adhesive film may include a film-shaped base material and a cured layer overlapping the base material.

The cured product is obtained by curing the component (C) in the adhesive composition (X) by reacting it. In addition, when the adhesive composition (X) contains the solvent (S), the cured product of the adhesive composition (X) does not need to contain the solvent (S). In this case, for example, a cured product is obtained by volatilizing the solvent (S) in the adhesive composition (X) and then reacting and curing the component (C).

The adhesive film of the present embodiment applies the adhesive composition ( It can be manufactured by curing with energy rays (UV, electron beam, etc.).

As a preferred form, the adhesive composition (X) is applied and then cured with active energy rays. In other words, the adhesive composition (X) can also be called an active energy ray-curable adhesive composition.

The substrate is, for example, in the form of a film or a sheet. The substrate is, for example, plastic film, plastic sheet, plastic foam, flat yarn, paper, metal plate, metal foil, woven fabric, non-woven fabric, or wood. Plastics include, for example, at least one member selected from the group consisting of polyolefins such as polyethylene and polypropylene, polyurethane, polyethylene terephthalate, polyvinyl chloride, rayon, and polyamide. The paper is, for example, Japanese paper or crepe paper.

The adhesive film having a cured layer made of a cured product of the adhesive composition ( Various uses such as marking (automotive molds, emblems, marks, etc.), masking (glass sealing, building curing, etc.), surface protection (painted surface protection, etc.), medical use (band-aids, etc.), and office use. It can be preferably used.

Additionally, the adhesive film of this embodiment can suppress deterioration of a metal (oxide) film, especially an ITO (indium tin oxide) film, and can therefore be suitably used for protecting electronic substrates. Additionally, the adhesive film of this embodiment has excellent bending resistance, so it is also useful for protecting flexible displays, for example.

Example

Hereinafter, the present embodiment will be further described through examples and comparative examples, but the present embodiment is not limited to these.

<Example 1>

100 parts by weight of acetone as a solvent was added to a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping funnel, and nitrogen gas introduction tube, and the temperature was raised to 57°C.

Next, while maintaining the inside of the reaction vessel at 57°C and blowing nitrogen into the reaction vessel while refluxing the solvent, a monomer blend solution having the following composition and an initiator solution 1 having the following composition were added into the reaction vessel using a dropping funnel. It was added dropwise continuously over 5 hours to allow radical polymerization to proceed within the reaction vessel.

Composition of monomer mixture: 88 parts by weight of 2-ethylhexyl acrylate (a1-1), 6.8 parts by weight of 2-hydroxypropyl acrylate (a22-3), 2-hydroxy-1-methylethyl acrylate (a21) -2) 2.3 parts by weight, 1.5 parts by weight of dimethylacrylamide (a3-1), and 1.5 parts by weight of diethylacrylamide (a3-2).

Composition of initiator solution 1: 0.07 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) [hereinafter sometimes abbreviated as V-65] and 20 parts by weight of acetone.

After completion of the dropwise addition, while maintaining the inside of the reaction vessel at 57°C and stirring the liquid in the reaction vessel, initiator solution 2 having the following composition was continuously dropped into the reaction vessel over 1 hour using a dropping funnel. Additionally, the polymerization reaction in the reaction vessel was continued for 1 hour under solvent reflux. In this way, the adhesive base material (B-1) containing the copolymer (A-1) was prepared in the reaction vessel. This adhesive base material (B-1) was taken out from the reaction vessel.

Composition of initiator solution 2: 0.10 parts by weight of 2,2'-azobis(2,4-dimethylbareronitrile) and 10 parts by weight of acetone.

And, the weight average molecular weight (Mw) of the copolymer (A-1) is 900,000, the glass transition temperature is -35°C, the hydroxyl group concentration is 0.7 mol/kg, the amide group concentration is 0.3 mol/kg, and the molar ratio (β) is 25/75, the carboxyl group concentration was 0 mol/kg.

<Examples 2 to 7, Comparative Examples 1 to 4>

The compositions of the monomer blend solution, initiator solution 1, and initiator solution 2 were changed as shown in Tables 1 and 2, and other than that, it was the same as Example 1, and copolymers (A-2) to copolymers (A- 11), respectively containing base material (B-2) to base material (B-11) for adhesives were obtained. The weight average molecular weight, glass transition temperature, hydroxyl group concentration, amide group concentration, molar ratio (β), and carboxyl group concentration of copolymer (A-2) to copolymer (A-11) are shown in Tables 1 and 2. .

[Table 1]

[Table 2]

<Examples 11 to 17, Comparative Examples 11 to 14>

The ingredients shown in “Blend Composition” in Tables 3 and 4 were mixed for 15 minutes using a mechanical stirrer. As a result, adhesive composition (X-1) to adhesive composition (X-11) were obtained.

Each of the adhesive composition (X-1) to the adhesive composition (X-11) was filmed on a 25-μm-thick polyester film [manufactured by Toray Co., Ltd., product name Lumiror Type T, polyethylene terephthalate ( A coating film was produced by applying a coating amount of 30 g/m ² to the surface of a PET film using a slot coater and drying it at 100°C for 1 minute with a downwind dryer. This coating film is irradiated with ultraviolet rays using a UV irradiation device (manufactured by Ushio Electric Co., Ltd., model number UVC-02516S1AA01) and using a metal halide lamp as a light source under the condition of an integrated light amount of 1000 mJ/cm ² to irradiate the coating film. It was cured to produce a cured layer with a thickness of 30 μm. As a result, an adhesive film (Yα) including a polyester film and a cured layer overlapping therewith was obtained.

In addition, each of the adhesive compositions (X-1) to the adhesive compositions (X-11) was subjected to a peeling treatment of a polyester film (polyethylene terephthalate film) with a thickness of 50 μm on one side of which a peeling treatment (silicone treatment) was applied. A coating film was produced by applying the coating to the applied surface to a thickness of 30 μm after drying and drying it with hot air at 100°C for 2 minutes. On this coating film, the peeled side of a polyester film with a thickness of 50 μm, which had been peeled (silicone treated) on one side separate from the above, was overlaid. This coating film was cured by irradiating ultraviolet rays under conditions of an integrated light amount of 1000 mJ/cm ² in the same manner as in the case of producing the adhesive film (Yα), thereby producing a cured layer with a thickness of 50 μm. As a result, an adhesive film (Yβ) was obtained in which a release film made of polyester film was overlapped on both sides.

The adhesive film (Yα) and the adhesive film (Yβ) were evaluated by the method described later. The results are shown in Tables 3 and 4.

<1> Adhesion at low temperatures

From the adhesive film (Yα), an adhesive film test piece with dimensions of 100 mm x 25 mm in plan view was cut out. Additionally, a 0.18 mm thick polyethylene terephthalate film with an ITO (indium tin oxide) film overlapping on one side was prepared. Under an atmosphere of 5°C, based on the “Adhesive Tape and Adhesive Sheet Test Method” specified in JIS Z0237-2000, an adhesive film test piece and a polyethylene terephthalate film were overlapped so that the cured layer and the ITO film were in contact. Subsequently, a load of 2 kg was applied with a roller on the adhesive film (Yα), and the roller was moved one round and round on the adhesive film (Yα). In this way, the adhesive film test piece and the polyethylene terephthalate film were bonded to obtain a laminated film.

This laminated film was left for 1 day under conditions of a temperature of 5°C and a relative humidity of 90%, and then the 180° peel strength of the adhesive film test piece against the polyethylene terephthalate film was measured at a width of 25 mm and a tensile speed in an atmosphere of 25°C. Measured under conditions of 300 mm/min. The results were evaluated according to the following evaluation criteria.

<Evaluation criteria>

AA: Greater than 9N/25mm.

A: Greater than 7N/25mm, less than 9N/25mm.

B: Greater than 5N/25mm, less than 7N/25mm.

C: 5N/25mm or less.

<2> Adhesion change at low temperature

A laminated film was produced in the same manner as in the case of <1> above.

This laminated film was left for 14 days under conditions of a temperature of 5°C and a relative humidity of 90%, and then in an atmosphere of 25°C, an adhesive film test piece for a polyethylene terephthalate film was prepared in the same manner as in the case of <1> above. The 180° peel strength was measured.

Accordingly, from the peel strength after 14 days obtained and the peel strength after 1 day obtained in <1> above, the change in adhesive force at low temperature was calculated using the following formula. The results were evaluated according to the following evaluation criteria.

(Change in adhesion at low temperature) = (Peel strength after 14 days) - (Peel strength after 1 day)

<Evaluation criteria>

AA: Greater than 1N/25mm, less than 2N/25mm.

A: Greater than 0.5N/25mm, less than 1N/25mm.

B: Greater than 0N/25mm, less than 0.5N/25mm.

C: 0N/25mm or less.

<3> Grass residue at low temperature

After peeling the adhesive film test piece from the polyethylene terephthalate film according to the test in <2> above, the surface of the ITO film on the polyethylene terephthalate film was visually observed to confirm the presence or absence of glue residue, and the results were evaluated according to the following evaluation criteria. evaluated.

<Evaluation criteria>

AA: No grass residue at all.

A: Almost no grass residue.

B: There is some grass residue.

C: There is grass residue.

<4> ITO layer deterioration test 1

After peeling the adhesive film test piece from the polyethylene terephthalate film according to the test <2> above, the electrical resistance value (R5) of the ITO film on the polyethylene terephthalate film was measured. In addition, before the test <2> above, the electrical resistance value (R0) of the ITO film in the polyethylene terephthalate film was measured in advance. Based on these, the change rate of the electrical resistance value of the ITO film was calculated using the following equation, and the results were evaluated based on the following evaluation criteria.

Rate of change (%)=[(R5)-(R0)]×100/(R0)

<Evaluation criteria>

AA: Change rate less than 5%.

A: Change rate more than 5%, less than 10%.

B: Change rate more than 10%, less than 20%.

C: Change rate of 20% or more.

<5> Adhesion at high temperatures

From the adhesive film (Yα) obtained above, an adhesive film test piece with dimensions of 100 mm x 25 mm in plan view was cut out. In addition, a 0.18 mm thick polyethylene terephthalate film with an ITO (indium tin oxide) film overlaid on one side was prepared. Under an atmosphere of 40°C, based on the “Adhesive Tape and Adhesive Sheet Test Method” specified in JIS Z0237-2000, an adhesive film test piece and a polyethylene terephthalate film were overlapped so that the cured layer and the ITO film were in contact. Subsequently, a load of 2 kg was applied with a roller on the adhesive film (Yα), and the roller was moved one round and round on the adhesive film (Yα). In this way, the adhesive film test piece and the polyethylene terephthalate film were bonded to obtain a laminated film.

This laminated film was left for 1 day under conditions of a temperature of 60°C and a relative humidity of 90%, and then the 180° peel strength of the adhesive film test piece against the polyethylene terephthalate film was measured at a width of 25 mm and a tensile speed in an atmosphere of 25°C. Measured under conditions of 300 mm/min. The results were evaluated according to the following evaluation criteria.

<Evaluation criteria>

AA: Greater than 9N/25mm.

A: Greater than 7N/25mm, less than 9N/25mm.

B: Greater than 5N/25mm, less than 7N/25mm.

C: 5N/25mm or less.

<6> Change in adhesion at high temperature

A laminated film was produced in the same manner as in the case of <5> above.

This laminated film was left for 14 days under conditions of a temperature of 60°C and a relative humidity of 90%, and then, in an atmosphere of 25°C, an adhesive film test piece for a polyethylene terephthalate film was prepared in the same manner as in the case of <5> above. The 180° peel strength was measured.

Accordingly, from the peel strength after 14 days obtained and the peel strength after 1 day obtained in above <5>, the change in adhesive force at high temperature was calculated using the following formula. The results were evaluated according to the following evaluation criteria.

(Change in adhesion at high temperature) = (Peel strength after 14 days) - (Peel strength after 1 day)

<Evaluation criteria>

AA: Greater than 1N/25mm, less than 2N/25mm.

A: Greater than 0.5N/25mm, less than 1N/25mm.

B: Greater than 0N/25mm, less than 0.5N/25mm.

C: 0N/25mm or less.

<7> Grass residue at high temperature

After peeling the adhesive film test piece from the polyethylene terephthalate film according to the test <6> above, the surface of the ITO film on the polyethylene terephthalate film was visually observed to confirm the presence or absence of glue residue, and the results were evaluated according to the following evaluation criteria. evaluated.

<Evaluation criteria>

AA: No grass residue at all.

A: Almost no grass residue.

B: There is some grass residue.

C: There is grass residue.

<8> ITO layer deterioration test 2

After peeling the adhesive film test piece from the polyethylene terephthalate film according to the test <6> above, the electrical resistance value (R40) of the ITO film on the polyethylene terephthalate film was measured. In addition, before the test <2> above, the electrical resistance value (R0) of the ITO film in the polyethylene terephthalate film was measured in advance. Based on these, the change rate of the electrical resistance value of the ITO film was calculated using the following equation, and the results were evaluated based on the following evaluation criteria.

Rate of change (%)=[(R40)-(R0)]×100/ (R0)

<Evaluation criteria>

AA: Change rate less than 5%.

A: Change rate more than 5%, less than 10%.

B: Change rate more than 10%, less than 20%.

C: Change rate of 20% or more.

<9> Bending durability test (room temperature characteristics: 20°C) (evaluation of bending resistance)

One release film was peeled from the adhesive film (Yβ) obtained above in which release films were overlapped on both sides. Next, in an atmosphere of 25°C, the adhesive film (Yβ) was superimposed on a polyimide film with a thickness of 50 μm. Subsequently, a load of 2 kg was applied with a roller on the adhesive film (Yβ), and the roller was moved one round and round on the adhesive film (Yβ). In this way, the adhesive film (Yβ) and the polyimide film were bonded. Subsequently, the other release film was peeled from the adhesive film (Yβ). As a result, a laminated film in which the adhesive film (Yβ) and the polyimide film were laminated was obtained.

This laminated film was tested under the following conditions using a bending tester (a rectangular unloaded U-shaped stretching tester manufactured by Yuasa System Equipment Co., Ltd.).

-Bending radius: 3mm.

-Number of bends: 10,000 times.

-Test temperature: 20℃.

Next, the appearance of the bent portion of the laminated film after the test was observed with the naked eye, and the results were evaluated using the following evaluation criteria.

<Evaluation criteria>

AA: No bending marks, white cloudiness, peeling, or lifting.

A: There are some bending marks, but there is no white cast, peeling, or lifting.

B: There are bend marks and white turbidity, but no peeling or lifting.

C: Bending marks, white turbidity, peeling, and lifting can be confirmed.

[Table 3]

[Table 4]

The details of the polyfunctional (meth)acrylate and initiator in Tables 3 and 4 are as follows.

-Multifunctional (meth)acrylate (C-1): Trimethylolpropane tri(meth)acrylate.

-Multifunctional (meth)acrylate (C-2): Dipentaerythritol pentaacrylate.

-Initiator (D-1): Brand name “omnirad 184”, manufactured by IGM Resins B.V., 1-hydroxycyclohexylphenyl ketone.

From the results in Tables 1 to 4, the adhesive films of Examples 11 to 17 have adhesion at low temperature (5°C) bonding and adhesiveness at high temperature (40°C) bonding compared to the adhesive films of Comparative Examples 11 to 14. It can be seen that this is excellent, and furthermore, the deterioration of the metal (oxide) film, especially the ITO (indium tin oxide) film, can be suppressed, and the bending resistance is excellent.

Claims (10)

Alkyl acrylate (a1) having an alkyl group having 4 to 8 carbon atoms, (meth)acrylate (a2) having a hydroxyl group, and dialkyl (meth)acrylamide having two alkyl groups each having 1 to 2 carbon atoms. A base material for an adhesive containing a copolymer (A) containing (a3) as a constituent monomer. According to paragraph 1,
A base material for an adhesive wherein the hydroxyl group concentration of the copolymer (A) is 0.01 mol/kg or more and 1.0 mol/kg or less. According to paragraph 1,
A base material for an adhesive wherein the molar ratio of primary hydroxyl groups to secondary hydroxyl groups of the copolymer (A) is from 0/100 to 90/10. According to paragraph 1,
A base material for an adhesive wherein the amide group concentration of the copolymer (A) is 0.01 mol/kg or more and 0.5 mol/kg or less. According to paragraph 1,
A base material for an adhesive wherein the carboxyl group concentration of the copolymer (A) is 0 mol/kg or more and 0.35 mol/kg or less. According to paragraph 1,
A base material for an adhesive, wherein the glass transition temperature of the copolymer (A) is -50°C or more and -30°C or less. According to paragraph 1,
A base material for an adhesive wherein the weight average molecular weight of the copolymer (A) is 300,000 or more and 1,200,000 or less. The base material for an adhesive according to any one of claims 1 to 7,
Containing polyfunctional (meth)acrylate (C),
Adhesive composition. According to clause 8,
With respect to the total weight of the copolymer (A) and the polyfunctional (meth)acrylate (C), the ratio of the copolymer (A) is 75% by weight or more and 99.9% by weight or less, and the polyfunctional (meth)acrylate (C) An adhesive composition wherein the proportion of acrylate (C) is 0.1% by weight or more and 25% by weight or less. An adhesive film having a cured layer made of a cured product of the adhesive composition according to claim 8.