TWI664254B - Adhesive composition for touch panel, adhesive sheet and laminate - Google Patents

Abstract

The present invention provides an adhesive composition for a touch panel, comprising: (A) an acrylic polymer having a weight average molecular weight of 100,000 or more and less than 800,000, and does not substantially contain an acidic group; and (B) ) A cross-linking agent, which is represented by the following general formula (1) or (2); and contains 0.04 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (A). (B) Crosslinking agent.

Description

Adhesive composition for touch panel, adhesive sheet, and laminated body

The present invention relates to an adhesive composition for a touch panel, an adhesive sheet, and a laminate.

Compared with image display devices, touch panels are mostly used in harsh environments such as indoors and outdoors (for example, in high temperature and / or high humidity environments). The adhesives of various components constituting the touch panel unit also require stable properties to be exhibited even under severe conditions.

In addition, since the touch panel unit of the laminated body of various members is disposed on the outermost surface of the screen, high transparency is required, and the moisture contained in the touch panel unit causes an adhesive contained in the touch panel unit. The layer is prone to foaming. In addition, it may be caused by gas such as water vapor or carbon dioxide generated from various members constituting the touch panel unit, and foaming may occur in the adhesive layer.

In recent years, in the touch panel of the mainstream electrostatic capacitance method, the conductive film forming the wiring is in direct contact with the adhesive. Therefore, the adhesive system is required not to change the characteristics of the conductive film.

The conductive film is usually formed of a metal or metal oxide such as indium tin oxide (ITO) or antimony tin oxide (ATO). Therefore, the conductive film is in contact with acid to cause corrosion. As a result, the resistance of the conductive film may increase. .

On the other hand, in order to improve the heat resistance or humidity and heat resistance of the adhesive layer, a method using an adhesive with an acid component is generally used. However, as described above, since the conductive film is easily corroded, it is difficult to use an acid component for the adhesive used in the touch panel. Therefore, the well-known adhesive composition must meet the requirements of high adhesion, high transparency, and non-corrosive conductive film characteristics (non-corrosive conductive film), and can suppress foaming under strict humidity and heat resistance conditions. Department is very difficult.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-77287

The present invention provides an adhesive composition, an adhesive sheet, and a laminate for a touch panel that can suppress foaming under humid and hot conditions, have excellent adhesion, durability, and transparency, and have non-corrosive properties of a conductive film. body.

In order to solve the aforementioned problems, the present inventors have found that even in the case of an adhesive composition containing an acrylic polymer that does not substantially contain an acidic group, it is possible to obtain a wet heat condition by using a specific crosslinking agent. An adhesive composition capable of suppressing foaming and having excellent transparency, adhesion, durability, and non-corrosiveness of the conductive film.

1. An adhesive composition for a touch panel according to the present invention, which comprises: (A) an acrylic polymer whose weight average molecular weight is 100,000 or more and less than 800,000, and does not substantially contain acid. And (B) a cross-linking agent, which is represented by the following general formula (1) or the following general formula (2); the (A) acrylic polymer contains (a1) an alkyl (meth) acrylate and (a2) A copolymer of a monomer component of a hydroxyl group-containing monomer, containing 0.04 parts by mass or more and 10 parts by mass or less of the (B) crosslinking agent with respect to 100 parts by mass of the acrylic polymer (A).

(In the formula, R ^1A , R ^1B , and R ^1C are independent and are a group containing a group represented by the following general formula (3) and / or a group represented by the following general formula (4). R ^2A , R ^2B , R ^2C is a group represented ^by- (CH ₂ ) _6- ), (In the formula, R ^1A , R ^1B , and R ^1C are independent and are a group containing a group represented by the following general formula (3) and / or a group represented by the following general formula (4). R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F are groups represented ^by- (CH ₂ ) _6- ), (Where x is an integer of 2 to 10 and m is an integer of 1 to 10), (In the formula, X is a single bond or -O-, y is an integer from 2 to 10 and n is an integer from 1 to 10).

2. The adhesive composition for a touch panel according to the above 1, wherein the monomer component may contain: the (a1) (meth) acrylic acid alkyl ester is 45% by mass or more and 99% by mass or less; a2) a hydroxyl-containing monomer is 1 mass% or more and 40 mass% or less; and a monomer other than the components (a1) and (a2) and having one olefinic double bond in the molecule is 0 mass % To 15% by mass.

3. The adhesive composition for a touch panel according to the above 2, wherein the monomer is a monomer other than the components (a1) and (a2) and has one olefinic double bond in the molecule, and the monomer The body composition may further contain (a3) a nitrogen-containing monomer, which is 0.1 mass% or more and 7 mass% or less; and (a4) is a monomer other than the (a1) component, the (a2) component, and the (a3) component, and The monomer having one olefinic double bond in the molecule is 0% by mass or more and 10% by mass or less (here, (a1) component + (a2) component + (a3) component + (a4) component = 100% by mass ).

4. One aspect of the present invention is an adhesive sheet for a touch panel, which is provided on one or both sides of a support with the adhesive composition for a touch panel according to any one of items 1 to 3 above.

5. A laminated body according to one aspect of the present invention includes an adhesive obtained from the first substrate, the second substrate, and the adhesive composition for a touch panel according to any one of items 1 to 3 above. Agent layer; the first substrate and the second substrate are bonded through the adhesive layer, and the first substrate and the second substrate each contain glass or resin.

When the adhesive composition for a touch panel according to items 1 to 3 is used, the (A) acrylic polymer and the (B) crosslinking agent are contained; the (A) acrylic polymer contains (a1) ( The copolymer of the monomer components of the alkyl (meth) acrylate and (a2) a hydroxyl group-containing monomer contains 0.04 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the (A) acrylic polymer. The aforementioned (B) crosslinking agent can form a highly elastic adhesive layer due to the structure of the (B) crosslinking agent. Thereby, generation of gas from a support or an adherend (hereinafter, also referred to as a "base material" in the present invention) can be suppressed, and generation of a gas from a reaction with the (B) crosslinking agent can be suppressed. Therefore, by using the aforementioned adhesive composition, it is possible to obtain an adhesive layer capable of suppressing foaming under moist heat conditions and having excellent transparency, adhesion, durability, and non-corrosiveness of the conductive film.

The adhesive sheet is obtained from the adhesive composition for a touch panel according to items 1 to 3 above, so it can suppress foaming under hot and humid conditions, and has excellent transparency, adhesion, durability, and non-conductive film. Corrosive.

The laminated body is an adhesive layer obtained by containing the adhesive composition for a touch panel according to items 1 to 3, and the adhesive layer is excellent because of the structure of the (B) crosslinking agent. The flexibility. Thereby, the adhesive layer system can escape the gas generated from the first substrate and the second substrate, and can suppress the gas generated from the reaction of the (B) crosslinking agent. Therefore, the laminated system can suppress foaming under moist heat conditions and has excellent transparency, and it is not easy to generate high adhesion due to the adhesive layer. And durability and peeling between the adhesive layer and the first substrate and the second substrate.

10‧‧‧ Adhesive layer

20‧‧‧ the first substrate

30‧‧‧ 2nd substrate

100‧‧‧Laminated body

FIG. 1 is a cross-sectional view schematically showing a laminated body according to an embodiment of the present invention.

Forms used to implement the invention

Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, unless otherwise specified, "part" means "mass part", and "%" means "mass%".

1. Adhesive composition for touch panel

An adhesive composition for a touch panel according to an embodiment of the present invention (hereinafter, sometimes referred to simply as an "adhesive composition") contains a weight average molecular weight of 100,000 or more and less than 800,000, and does not substantially Acidic group-containing acrylic polymer (A) (hereinafter, may be abbreviated as "(A) component"); and a crosslinking agent (B) represented by the following general formula (1) or the following general formula (2) ) (Hereinafter may be abbreviated as "(B) component").

(In the formula, R ^1A , R ^1B , and R ^1C are independent and are a group containing a group represented by the following general formula (3) and / or a group represented by the following general formula (4). R ^2A , R ^2B , R ^2C is a group represented ^by- (CH ₂ ) _6- ), (Wherein R ^1A , R ^1B , and R ^1C are each independently a group represented by the following general formula (3) and / or a group represented by the following general formula (4): R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , R ^3F are groups represented ^by- (CH ₂ ) _6- ), (Where x is an integer of 2 to 10 and m is an integer of 1 to 10), (In the formula, X is a single bond or -O-, y is an integer of 2 to 10 and n is an integer of 1 to 10).

1.1. (A) Ingredient

The component (A) contains (a1) (meth) acrylic acid alkyl ester (hereinafter, sometimes referred to simply as "(a1) component") and (a2) a hydroxyl-containing monomer (hereinafter, sometimes referred to simply as "(A2) component") is a copolymer of monomer components. The component (a1) and the component (a2) are preferably those having no acidic group.

In the present invention, the "acrylic polymer" includes at least one selected from the group consisting of acrylic acid, acrylate, acrylate, methacrylic acid, methacrylate, and methacrylate in the constituent unit. Of polymers.

(A) The component system does not contain an acidic group substantially. Here, all The component (A) does not have an acidic group, and means that the content of the monomer having an acidic group in the aforementioned monomer component is 0.5% by mass or less (preferably 0% by mass), preferably in the aforementioned monomer component. However, a monomer having an acidic group was not intentionally blended. More specifically, when the component (A) does not have an acidic group, the acid value of the component (A) is usually 0.5 mg / KOH or less. Since the component (A) does not substantially contain an acidic group, it is possible to prevent the conductive film contained in the touch panel from being corroded. The "acidic group" in the present invention is not limited, and examples thereof include a carboxyl group, a sulfoxyl group, and a cyano group.

The content of the component (A) in the adhesive composition (solid content after removal of the solvent) of the adhesive composition (solid content after removing the solvent) of the adhesive composition of this embodiment may be 90 parts by mass or more and 99.9 parts by mass. the following.

From the viewpoints that the elasticity can be more reliably maintained under moist heat conditions and foaming can be more suppressed under moist heat conditions, in the adhesive composition of this embodiment, the monomer component may contain (a1) component at 45% by mass or more. And 99% by mass or less (preferably 62% by mass or more and 98% by mass or less); and (a2) 1% by mass or more and 40% by mass or less (preferably 2% by mass or more and 30% by mass or less) (herein (The total amount of monomers in the monomer component is set to 100% by mass). At this time, the total amount of the (a1) component and the (a2) component of the monomer component is preferably 85% by mass or more and 100% by mass or less. The monomer component may further contain a monomer other than the component (a1) and the component (a2) of 0% by mass to 15% by mass, and a monomer having one olefinic double bond in the molecule.

Obtained from the adhesive composition of this embodiment The pressure-sensitive adhesive layer is capable of suppressing foaming under hot and humid conditions, which means that it has durability in use under high temperature and / or high humidity conditions such as in a car, outdoor, steam bath, and bathroom. In particular, the portable touch panel type image display device is intended to be used in various environments, and it can suppress foaming from being used under hot and humid conditions, and has adhesion, durability, transparency, and non-corrosive conductive film. In terms of properties, the adhesive layer obtained from the adhesive composition of this embodiment is useful.

1.1.1. (A1) Ingredients

(a1) component is a component which can contribute to the adhesive force of the adhesive composition of this embodiment. (a1) A component system can be represented by following formula (5), for example.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group or an aralkyl group).

In the general formula (5), the alkyl group represented by R ² may be linear or branched, and examples thereof include alkyl groups having 1 to 18 carbon atoms (for example, methyl, ethyl, N-propyl, isopropyl, n-butyl, isobutyl, third butyl, n-pentyl, isopentyl, neopentyl, third pentyl, 2-methylbutyl, 1-methylbutyl Base, n-hexyl, isohexyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, n-nonyl , N-decyl, isodecyl, n-undecyl, n-dodecyl (lauryl), n-tridecyl, n-tetradecyl (myristoyl), iso-myristyl, n-hexadecyl (palmityl) ), N-octadecyl (stearyl), isostearyl) and the like.

In the above general formula (5), the "aralkyl group" refers to an alkyl group in which a hydrogen atom of one alkyl group is substituted with an aryl group. Examples of the aralkyl group represented by R ² in the general formula (5) include aralkyl groups having 1 to 18 carbon atoms (for example, benzyl (phenylmethyl), phenethyl (phenyl Ethyl)).

(a1) A component system can be used combining 1 type or 2 or more types. In particular, the aforementioned monomer component, because it can maintain adhesion better, contains 35% by mass or more (preferably) 99% by mass or less of the monomer component selected from 2-ethylhexyl acrylate and methyl One or more of 2-ethylhexyl acrylate and n-butyl acrylate are preferred.

1.1.2. (A2) Ingredient

The (a2) component system can contribute to the reaction with the (B) component to form a crosslinked structure. More specifically, a cross-linked structure can be formed by reacting a hydroxyl group contained in the component (a2) with an isocyanate group in the component (B).

Examples of the component (a2) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and methyl formate. 4-hydroxybutyl acrylate, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacrylate Among the hydroxyl-containing (meth) acrylates such as hydroxy-3-phenoxypropyl ester, etc., one type or a combination of two or more types can be used. Especially as (a2) component, it is It is preferable to use a hydroxyl group-containing (meth) acrylate having 1 to 6 carbon atoms.

1.1.3. (A3) Ingredient

The monomer component is a monomer other than the component (a1) and the component (a2) and has one olefinic double bond in the molecule, and can further contain 0% by mass or more and 7% by mass or less ( a3) Nitrogen-containing monomer (hereinafter, sometimes referred to simply as "(a3) component").

Examples of the component (a3) include N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, Acrylamide, N, N-dimethylaminopropylacrylamide, diacetone acrylamide, and acrylmorpholine can be used singly or in combination of two or more. Among them, acrylamide is more preferred as the component (a3) because it has excellent efficiency in forming a crosslinked structure.

In order to more surely suppress foaming under moist heat conditions, and to obtain an adhesive layer having more excellent durability, the content of the component (a3) in the monomer component is 0 mass% or more and 5 masses. % Or less is preferable, 0.1 mass% or more is preferable, 0.2 mass% or more is preferable, and 4 mass% or less is more preferable.

1.1.4. (A4) Ingredients

In addition, the monomer component for obtaining the polymer of the component (A) may further contain (a4) of 0% by mass to 10% by mass, which is (a1) component, (a2) component, and ( a3) A monomer other than the component and having in the molecule One olefinic double bond monomer (hereinafter, sometimes referred to simply as "(a4) component"). In this specification, (a1) component + (a2) component + (a3) component + (a4) component = 100% by mass. That is, the (A) component can be a copolymer of a monomer component containing (a1) component, (a2) component, and (a3) component and / or (a4) component as needed.

Examples of the component (a4) include vinyl acetate, styrene, acrylonitrile, macromonomers having a radical polymerizable vinyl group at the end of a monomer obtained by polymerizing a vinyl group, (meth) acrylic acid, Monomers having a carboxyl group, such as itaconic acid and maleic acid. In order to adjust the acid value of the component (A) to prevent corrosion of the conductive film, the content of the component (a4) in the monomer component is preferably 0% by mass or more and 0.2% by mass or less.

1.1.5.Tg

From the viewpoint of more reliably achieving good adhesion and durability and reducing light leakage, the Tg of the component (A) of the adhesive composition of this embodiment is preferably -80 ° C or higher and 20 ° C or lower. It is preferably -80 ° C or higher and 0 ° C or lower. In the present invention, the Tg of the component (A) is a value calculated from the following formula (6) (formula of FOX).

_{1 / Tg A = W a1 /} Tg a1 + W a2 / Tg a2 + W a3 / Tg a3 + W a4 / Tg a4 ‧‧‧‧ (6) ( in the formula, Tg _A is the glass transition lines (A) component Temperature (K), Tg _a1 , Tg _a2 , Tg _a3 , and Tg _a4 each represent the glass transition temperature of the homopolymer prepared from the constituent monomers (a1), (a2), (a3), and (a4) ( Tg (K)), W _a1 , W _a2 , W _a3 , and W _a4 each represent the weight of the component (a1), (a2), (a3), and (a4) contained in the component (A) Score).

In addition, since the Tg _A system is calculated as the absolute temperature (K) in the above formula (6), it can be converted into a Celsius temperature (° C) if necessary.

The glass transition temperature of a homopolymer prepared from a representative monomer is shown in Table 1 below. More specifically, it is described in, for example, the Polymer Handbook Fourth Edition (Wiley-Interscience). , 1999) and so on.

1.1.7. Weight average molecular weight (Mw)

In addition, from the viewpoint of achieving better adhesion and durability, the weight average molecular weight (Mw) of the component (A) of the adhesive composition of this embodiment is 50,000 or more and 750,000 or less. More preferably, more than 100,000 is more preferable, more than 150,000 is more preferable, on the other hand is preferably less than 600,000, more preferably less than 500,000, more preferably less than 400,000. Here, the weight average molecular weight of (A) component uses GPC (gel permeation chromatography), and the weight average molecular weight (Mw) of a standard polystyrene conversion was calculated | required under the following conditions.

<GPC measurement conditions>

Measuring device: HLC-8120GPC (manufactured by TOSOH)

GPC column configuration: The following 5 connection columns (all manufactured by TOSOH)

(1) TSK-GEL HXL-H (protection column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

Sample concentration: diluted with tetrahydrofuran so as to be 1.0 mg / cm ³

Mobile phase solvent: tetrahydrofuran

Flow: 1.0cm ³ / min

Column temperature: 40 ℃

1.2. (B) ingredients

As described above, in the adhesive composition of this embodiment, the crosslinking agent of the component (B) contains a crosslinking agent represented by the general formula (1) or the general formula (2).

In the adhesive composition of this embodiment, from the viewpoint of providing more excellent adhesion and durability and more reliably preventing light leakage, R contained in the general formula (1) or the general formula (2) ^1A , ^R1B , and ^{R1C are} the groups represented by the general formula (3), x is an integer of 2 or more and 10 or less (more preferably, it is an integer of 4 or more and 8 or less), and m is 1 or more and 10 The following integer is preferable (more preferably, it is an integer of 1 or more and 6 or less).

In addition, in the group represented by the above-mentioned general formula (4) for R ^1A , R ^1B , and R ^1C contained in the general formula (1) or the general formula (2), an integer of 2 or more and 10 or less is y. Preferably, an integer of 4 to 8 is more preferable, n is an integer of 1 or more and 10 or less, and an integer of 1 to 6 is more preferable. Further, in the general formula (1) and the general formula (2), R ^1A , R ^1B , and R ^1C may be the same or different, or a plurality of them may be combined.

(B) component-based isocyanate-based cross-linking agent, more specifically, component (B) has a skeleton derived from trimethylolpropane as shown in the above general formula (1) or (2) (-( O-CH _2- ) ₃ -C-CH ₂ CH ₃ ), and an isocyanate (-N = C = O) group.

From the viewpoint of imparting appropriate elasticity to the adhesive composition of this embodiment, the (B) component system can be, for example, a degree of crosslinking (the number of isocyanate groups contained in one molecule of the (B) component) is 1. It is preferably from 9 to 9, and the degree of crosslinking is preferably from 3 to 6. The (B) component system can be obtained, for example, by condensing trimethylolpropane and a halogen halide (or an ester, or a carboxylic acid) having an isocyanate group.

From the viewpoint of improving the elasticity of the adhesive composition of this embodiment, the molecular weight of the component (B) is preferably 500 or more and 10,000 or less, and more preferably 2,000 or more and 7,000 or less.

In contrast, the adhesive composition of the present embodiment contains the component (B) due to the group represented by the general formula (3) and / or the general formula (4) contained in the component (B). Group (adjacent to a linear structure derived from a trimethylolpropane skeleton (in the general formula (1) and the general formula (2), R ^1A , R ^1B , and R ^1C are represented)), Improve the elasticity of the adhesive composition. This makes it possible to suppress gas generated from the adhesive layer and the substrate (for example, glass and polycarbonate) to be bonded. In addition, since the stability of the component (B) with respect to water and a hydroxyl group is high, the gas (for example, carbon dioxide, water vapor, monomers, Products, etc.) are less.

As described above, the adhesive layer obtained from the adhesive composition of this embodiment can suppress the generation of gas from the base material, and since less gas is generated from the adhesive layer itself, it is possible to suppress the generation of hair under hot and humid conditions. bubble.

From the viewpoint of suppressing foaming and improving adhesion and durability, the content of the component (B) in the adhesive composition of the present embodiment is 0.04 based on 100 parts by mass of the component (A) of the present embodiment. It is preferably more than 10 parts by mass, more preferably more than 0.05 parts by mass and less than 10 parts by mass, more preferably 0.06 parts by mass or more, particularly preferably 0.07 parts by mass or more, and 2 parts by mass Serve below.

As (B) component, a commercially available crosslinking agent can be used. For example, as component (B), D-94 (Sales Office: Asahi Kasei Corporation), E405-70B (Sales Office: Asahi Kasei Corporation), MFA-75B (Sales Office: Asahi Kasei Corporation) can be used.

Compared with the cross-linking agent (for example, commercially available isocyanate-based cross-linking agent L-45 (Sales Office: Soken Chemical Co., Ltd.), CORONATE HL ( Sales Office: POLYURETHANE Co., Ltd., etc.) When using the adhesive composition for a touch panel according to this embodiment, the adhesive composition containing the general formula (1) or the general formula is used. The crosslinking agent (B) shown in (2) has high elasticity and can suppress foaming.

Examples of the (B) crosslinking agent include the crosslinking agents 1 to 3 described in Examples described later.

1.3. Other ingredients 1.3.1. (C) Silane coupling agent

The adhesive composition of this embodiment can further contain components other than (A) component and (B) component as needed. For example, the adhesive composition of this embodiment can also be formulated with (C) a silane coupling agent (hereinafter, also sometimes simply referred to as "(C) component") and (D) ionicity within a range that does not impair the effect of the present invention. Compounds (hereinafter may be abbreviated as "(D) component"), antioxidants, ultraviolet absorbers, tackifiers, plasticizers, and the like.

(C) The component is, for example, a silicon compound containing a polymerizable unsaturated group such as vinyltrimethoxysilane, vinyltriethoxysilane, and methyltripropoxypropyltrimethoxysilane; 3- Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, etc. Silicon compounds of oxygen structure; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-amine Amino-containing silicon compounds such as propylmethyldimethoxysilane; and 3-chloropropyltrimethoxysilane; oligomeric silane coupling agents, etc., which are not prone to spalling especially in hot and humid environments A silane coupling agent having a functional group that reacts with a functional group contained in the component (A) is preferred.

(C) component is mix | blended with the adhesive composition of this embodiment In this case, the content of the component (C) can be 0.01 parts by mass or more and 0.5 parts by mass or less, and preferably 0.05 parts by mass or more and 0.3 parts by mass or less with respect to 100 parts by mass of the component (A).

1.3.2. (D) Ionic compounds

Moreover, the adhesive composition of this embodiment may contain (D) an ionic compound. Examples of the component (D) include ionic compounds composed of anions and cations that are liquid or solid at 25 ° C, and specific examples include alkali metal salts and ionic liquids (25 ° C Liquid), surfactants, etc.

The content of the component (D) in the adhesive composition of this embodiment can be 0.01 mass parts or more and 3 mass parts or less, and 0.05 mass parts or more and 2.5 mass parts with respect to 100 mass parts of the (A) component of this embodiment. The following is better.

1.4. (A) Polymerization method of component

(A) The polymerization method of the component is not particularly limited. It can be polymerized by a well-known method such as solution polymerization, emulsion polymerization, suspension polymerization, and the like, and a mixture of copolymers obtained from the polymerization is used to produce the adhesive of the present invention. In the case of a composition, from the viewpoint of relatively simple processing steps and being able to be performed in a short time, it is preferable to polymerize by solution polymerization.

Solution polymerization is generally performed by adding a predetermined organic solvent, each monomer, a polymerization initiator, and a chain transfer agent that can be used as needed in a polymerization tank under a nitrogen stream or an organic solvent reflux temperature. The reaction was allowed to proceed for several hours while stirring.

In this case, at least a part of the organic solvent, the monomer, and / or the polymerization initiator may be sequentially added. Examples of the organic solvent include benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p-xylene, tetrahydronaphthalene, decahydronaphthalene, and aromatic petroleum naphthalene. Aromatic hydrocarbons; for example, aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, petroleum spirits, petroleum naphtha, turpentine Types; for example, esters of ethyl acetate, n-butyl acetate, n-pentyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate, and the like ; For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methyl cyclohexanone; for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Glycol ethers such as ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; for example, methanol, ethanol, n-propanol, isopropanol, n- Alcohols such as butanol, isobutanol, second butanol, and third butanol, and the like. These organic solvents can be used individually or in mixture of 2 or more types.

Among the organic solvents for polymerization, when the component (A) is polymerized, it is an organic solvent that does not easily undergo chain transfer during the polymerization reaction. For example, esters and ketones are preferably used, and in particular, the component (A) is used. In terms of solubility, ease of polymerization reaction, and the like, it is preferable to use ethyl acetate, methyl ethyl ketone, acetone, and the like.

As said polymerization initiator, the organic peroxide, azo compound, etc. which can be used for general solution polymerization can be used. Examples of such an organic peroxide include third butyl hydrogen peroxide, isopropyl Benzene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauryl peroxide, hexamidine peroxide, diisopropyl peroxide, di-2-ethylhexyl peroxide, T-butyl peroxypivalate, 2,2-bis (4,4-di-tert-butylcyclohexyl peroxide) propane, 2,2-bis (4,4 -Di-tertiary pentylcyclohexyl peroxide) propane, 2,2-bis (4,4-di-tertiary octyl cyclohexyl peroxide) propane, 2,2-bis (4,4-di-α -Cumyl peroxide cyclohexyl) propane, 2,2-bis (4,4-di-third-butylcyclohexyl peroxide) butane, 2,2-bis (4,4-di-third Examples of azo compounds include 2,2′-azobis-isobutyronitrile and 2,2′-azobis-2,4-dimethylvaleronitrile. , 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile and the like.

Among these polymerization initiators, a polymerization initiator that does not cause a graft reaction during the polymerization reaction of the component (A) is preferred, and an azo-based polymerization initiator is particularly preferred. The usage amount is usually 0.01 parts by mass or more and 2 parts by mass or less, preferably 0.1 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the total monomer.

In the production of the component (A) contained in the adhesive composition of the present invention, a chain transfer agent is usually not used, but it can also be used as needed, as long as the object and effect of the present invention are not impaired.

Examples of such a chain transfer agent include cyanoacetic acid; alkyl esters of cyanoacetic acid having 1 or more and 8 carbon atoms; bromoacetic acid; alkyl esters of bromoacetic acid having 1 or more and 8 carbon atoms; anthracene , Phenanthrene, pyrene, 9-phenylpyrene and other aromatic compounds; p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene and other aromatic compounds Group nitro compounds; benzoquinone derivatives such as benzoquinone, 2,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tetrabutylborane; carbon tetrabromide; Halogenated hydrocarbons such as carbon chloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, and 3-chloro-1-propane; chloral ), Furaldehyde (furaldehyde) and other aldehydes: alkyl thiols having 1 or more and 18 carbon atoms; aromatic thiols such as thiophenol and tolthiol; hydrothioacetic acid, hydrothioacetic acid Alkyl esters having 1 to 10 carbon atoms; hydroxyalkyl mercaptans having 1 to 12 carbon atoms; terpenes such as pinene and terpinolene.

The polymerization temperature of the component (A) is usually in the range of about 30 ° C to 180 ° C, preferably 40 ° C to 150 ° C, and more preferably 50 ° C to 90 ° C. When the polymer obtained by the solution polymerization method or the like contains an unreacted monomer, in order to remove the monomer, it may be purified by a reprecipitation method using methanol or the like.

1.5. Manufacture of adhesive composition

The adhesive composition according to this embodiment is generally capable of being prepared by mixing the aforementioned (A) component and (B) component, and optionally any components at the same time or in an arbitrary order. When the component (A) is mixed with the component (B) and the component (A) is prepared by solution polymerization, the component (B) may be added to a solution containing the component (A) after the polymerization is completed, but by When the component (A) is prepared by block polymerization, it is difficult to uniformly mix the component after the polymerization is completed. Therefore, it is preferable to add the component (B) and mix it during the polymerization.

1.6. Uses and effects

The adhesive composition of this embodiment can be suitably used as an adhesive for touch panels. When the adhesive composition of this embodiment is used, excellent durability can be exhibited under moist heat conditions, and when it is used for adhering to an adherend on a substrate (for example, glass or resin), it can be suppressed under moist heat conditions. Foam is generated in the adhesive layer.

There are two main reasons why foaming occurs in the adhesive layer. The first reason is the gas generated by the substrate bonded to the adhesive layer. The second reason is due to the gas generated by the components constituting the adhesive layer.

First, the first cause of the gas from the substrate is a gas generated from an organic material (resin) such as polycarbonate, polymethyl methacrylate, and polyimide.

For example, in terms of material characteristics, polycarbonate is known to generate exhaust gas (CO ₂ ) under high temperature conditions. In addition, polycarbonates easily pass water vapor (H ₂ O), and particularly under high temperature conditions, the transmission of water vapor is significant. Due to these gases, foaming may occur in the adhesive layer to which the polycarbonate is bonded. In the case of polymethyl methacrylate, water vapor and unreacted monomer may be generated as a gas.

The second reason is that the gas due to the components constituting the adhesive layer is a gas generated by the reaction of the components contained in the adhesive composition. For example, in an isocyanate-based crosslinking agent, isocyanate groups react with water to generate carbon dioxide.

In this regard, one of the adhesive compositions of this embodiment is It is estimated that the foaming prevention characteristics of each effect are obtained by the following action mechanisms.

That is, when using the adhesive composition of this embodiment to provide an adhesive layer on the surface of a substrate, the component (B) contained in the adhesive composition is used as described above in the component (B). As a result of improving the elasticity of the group represented by the general formula (1) and / or the group represented by the general formula (2), it is possible to suppress the generation of gas from the substrate. In addition, in the adhesive composition of this embodiment, the gas generated by the reaction with the component (B) is small. According to the above, when the adhesive composition of this embodiment is used to form an adhesive layer for bonding members constituting a touch panel, the adhesive layer can suppress foaming, and the adhesive layer has excellent Adhesive force and durability (damp heat durability). Therefore, when the members constituting a touch panel are bonded together by using this adhesive layer, peeling does not easily occur. Moreover, since the adhesive composition system of this embodiment does not contain an acid component, it has the outstanding non-corrosiveness of a conductive film.

2. Adhesive sheet

An adhesive sheet (adhesive layer) according to another embodiment of the present invention includes an adhesive layer containing the adhesive composition for a touch panel of the above embodiment on one or both sides of a support.

When manufacturing the adhesive sheet of this embodiment, the above-mentioned adhesive layer can be obtained by using a gravure coater, Mayer's bar coater, pneumatic blade coater, roll coater, etc. The composition is coated on a support, and the adhesive composition applied on the adhesive sheet is formed by drying and crosslinking at normal temperature or heating, or an adhesive layer may also be formed. It is formed by putting it on a peeling film and transferring it to an adherend.

The thickness of the adhesive sheet is usually a dry thickness of 10 μm or more and 1000 μm or less, preferably 25 μm or more and 500 μm or less. In addition, before using the adhesive sheet, a peeling film may be laminated on the surface of the adhesive layer to protect the adhesive layer.

Examples of the support system include polycarbonate, polymethyl methacrylate, polyester such as polyethylene terephthalate (PET), cellulose triacetate (TAC), polyfluorene, polyimide, and polyimide. Organic polymers such as styrene, polytetrafluoroethylene, polyethylene, polyvinyl chloride, and glass.

Examples of the adherend include glass with a conductive film layer, resin film with a conductive film, polycarbonate, polymethyl methacrylate, polyester such as polyethylene terephthalate (PET), and triacetic acid. Organic polymers such as cellulose (TAC), polyfluorene, polyimide, polystyrene, polytetrafluoroethylene, polyethylene, polyvinyl chloride, and glass.

The thickness of the support or adherend (substrate) is not particularly limited, and in the case of an organic polymer, it is preferably 12 μm or more and 75 μm or less. Moreover, the said base material system can have any form of a single layer and multiple layers. In addition, a well-known and commonly used surface treatment such as a physical treatment such as a corona discharge treatment, a plasma treatment, or a chemical treatment such as a primer treatment may be performed on the surface of the substrate. In the case of glass, the thickness is preferably 25 μm or more and 2000 μm or less.

3.Laminated body

A laminated body 100 according to an embodiment of the present invention includes a first substrate 20, a second substrate 30, and an adhesive layer 10 as shown in FIG. 1; the first substrate 20 and the second substrate 30 are transparent. The adhesive layer 10 is bonded together.

The laminated body of this embodiment can be obtained by the step of bonding the first substrate and the second substrate through the adhesive layer obtained from the adhesive composition for a touch panel described in the above embodiment. .

More specifically, the adhesive sheet (adhesive layer 10) obtained from the adhesive composition for a touch panel of the above-mentioned embodiment can be attached to the first base material 20 or the second base material 30, and can be disposed on the first base material 20 or the second base material 30. Between the first base material 20 and the second base material 30. That is, after the surface of the adhesive layer 10 is attached to either the first substrate 20 or the second substrate 30, the other surface (back surface) of the adhesive layer 10 is attached to the first The other surface of the second base material 30 or the first base material 20 can be bonded to the first base material 20 and the second base material 30 via the adhesive layer 10.

Each of the first base material 20 and the second base material 30 can contain glass or resin. As an example, the first base material 20 may contain glass, and the second base material 30 may contain resin.

Examples of the resin constituting the first base material 20 and / or the second base material 30 include the organic polymer exemplified above as a support. Due to the additional heat, gas contained in the resin, gas generated by decomposition of the resin, monomers derived from raw materials of the resin, and gas produced as a by-product may be generated from the resin. Since the adhesive layer 10 is obtained from the adhesive composition of this embodiment and has high elasticity, it is possible to suppress the generation of gas from the first substrate 20 and / or the second substrate 30.

The laminated body 100 of this embodiment is adhered by the first base material 20 and the second base material 30 through the adhesive layer 10, and in addition to the elasticity of the adhesive layer 10, the adhesive layer 10 can be suppressed from the first layer In addition to the gas generated from the 1 base material 20 and / or the second base material 30, the gas generated from the adhesive layer 10 itself is also small. Therefore, it is possible to suppress foaming in the adhesive layer 10. Therefore, the adhesive layer 10 has excellent transparency, and the first base material 20 and the second base material 30 are bonded together by the adhesive layer 10 having excellent adhesive force, so that the laminated body 100 is unlikely to peel off.

4. Examples

Hereinafter, the present invention will be described based on the following examples, but the present invention is not limited to the examples.

4.1. (A) Component modulation 4.1.1. Modulation of polymers A, C to G

To a reaction device equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen introduction tube, a monomer component having a blending ratio shown in Table 2 below was added, and then ethyl acetate was added at a blending amount with a monomer concentration of 50% by mass. ester. Next, 0.1 part by mass of azobisisobutyronitrile was added, and the temperature was raised to 60 ° C. while stirring while replacing the air in the reaction vessel with nitrogen, and then allowed to react for 6 hours. After completion of the reaction, the solution was diluted with ethyl acetate (solvent) to obtain a solution of the component (A) (acrylic polymers A to E). The acid values of the acrylic polymers A and C to F were 0 mg / KOH. The acid value of the acrylic polymer G was 4 mg / KOH.

4.1.2. Preparation of polymer B

To a reaction device equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen introduction tube, a monomer component having a blending ratio shown in Table 2 below was added, and then ethyl acetate was added at a blending amount with a monomer concentration of 40% by mass. ester. Next, 0.1 parts by mass of azobisisobutyronitrile was added, and the temperature was increased to 60 ° C. while stirring while replacing the air in the reaction vessel with nitrogen, followed by a reaction for 6 hours. After completion of the reaction, it was diluted with ethyl acetate (solvent) to obtain a solution of the component (A) (acrylic polymer B). The acid value of the acrylic polymer B was 0 mg / KOH.

4.2. Preparation of adhesive composition and production of adhesive sheet for evaluation

Using the component (A) obtained in the above 4.1., The components were added according to the following Table 3 (in Table 3, the amount of each component represents the proportion of the solid content after removing the solvent) to obtain Examples 1 to 9 And solutions of the adhesive composition of Comparative Examples 1 to 7.

Next, the solution of the adhesive composition was coated on the surface of the polyester film after the peeling treatment and dried to obtain an adhesive sheet having an adhesive layer having a thickness of 50 μm. This adhesive sheet was aged at 23 ° C / 50% RH for 7 days in a dark place, and then attached to one side of a polybutylene terephthalate film having a film thickness of 100 µm to obtain an adhesive sheet for evaluation.

As the component (B), as shown in Table 3 below, the crosslinking agents 1 to 3 were used. Each of the crosslinking agents 1 to 5 has a structure shown by the following structural formulae (7) to (11). Moreover, the weight average score of the crosslinking agent 1 The molecular weight (MW) is about 4,000, the weight average molecular weight (MW) of the crosslinking agent 2 is, for example, about 3,700, and the weight average molecular weight (MW) of the crosslinking agent 3 is, for example, about 4,000.

[Crosslinking agent 1]

(In the formula, l is 1 or more and 10 or less, m is 1 or more and 10 or less, and n is 1 or more and 10 or less).

[Crosslinking Agent 2]

(In the formula, l is 1 or more and 10 or less, m is 1 or more and 10 or less, n is 1 or more and 10 or less, a is 1 or more and 10 or less, b is 1 or more and 10 or less, and c is 1 or more and 10 or less. the following).

[Crosslinking Agent 3]

(In the formula, l is 1 or more and 10 or less, m is 1 or more and 10 or less, and n is 1 or more and 10 or less).

[Crosslinking agent 4]

[Crosslinking agent 5]

For each evaluation adhesive sheet, the 180 ° peeling force and moisture resistance durability were evaluated using the following methods (Table 3).

4.3. Evaluation method 4.3.1. 180 ° peeling force (adhesive force)

The adhesive sheet for evaluation obtained in the above 4.2 was cut into 25 mm × 150 mm, and the one-sided release sheet was peeled off and attached to each adherend described in Table 3 using a roller weighing 2 kg for 3 round trips. Pressure stick. After being pressed for 20 minutes in an environment of 23 ° C. × 50% RH, the short side of the test piece was stretched at a peeling speed of 300 mm / min in a direction of 180 ° and the average value of the measured values 10 times was set as the peeling force. .

4.3.2. Moisture resistance and durability

The adhesive sheet for evaluation obtained in 4.2 above was cut into 50 mm × 60 mm, and the release sheet on one side was peeled off and attached to each of the adherends described in Table 3, and pressed back and forth 3 times using a 2 kg roller. After pressure bonding, autoclave treatment was performed at 50 ° C. × 5 atm for 20 minutes. Next, after standing at room temperature for 1 hour, leaving it to stand at 85 ° C / 85% RH for 24 hours and leaving it at 23 ° C / 50% RH for 1 hour, the presence or absence of foaming in the adhesive layer was visually confirmed. The evaluation criteria are as follows.

(Evaluation)

○: Bubbles could not be confirmed visually on the adhesive layer.

×: Large bubbles can be confirmed visually on the adhesive layer. Or the adhesive layer floats from the support or the adherend.

4.3.3. Non-corrosive conductive film

The adhesive sheet for evaluation obtained in 4.2 above was cut into 10 mm × 60 mm, and the release sheet on one side was peeled off and attached to an ITO vapor-deposited PET film cut into 10 mm × 100 mm. The autoclave treatment was performed at 50 ° C. × 5 atm. 20 minutes. Next, after standing at room temperature for 1 hour, it was left to stand at 60 ° C and 90% RH for 500 hours, and at 23 ° C and 65% RH for 1 hour, and then the resistance value of the ITO vapor-deposited film was measured. In addition, the resistance value is compared with the resistance value measured before the test and the change rate of the resistance value with respect to the resistance value before the test is obtained. The measurement of the resistance value was performed using TESTER (Sanwa Electric Co., Ltd., DIGITAL MULTIMETER PC510).

(Evaluation)

○: The rate of change of the resistance value with respect to the resistance value before the test did not reach 115%

×: The rate of change of the resistance value with respect to the resistance value before the test is 115% or more

4.3.4. Haze of flakes

After the defoaming treatment, each of the adhesive compositions of Examples 1 to 9 and Comparative Examples 1 to 7 was applied to a polyethylene terephthalate film after peeling treatment with a thickness of 38 μm using a doctor blade (hereinafter: isolation Film), and dried at 90 ° C. for 3 minutes to form a coating film having a dry film thickness of 50 μm. On the opposite side of the coating film from the above-mentioned polyethylene terephthalate film, the release film was further bonded to obtain an adhesive sheet for evaluation with an adhesive layer having a thickness of 50 μm, wherein the adhesive layer was Clamped by 2 isolation films. Second, will use The one-sided release film of the above-mentioned adhesive sheet for evaluation obtained by the method described in this column was peeled off, and was attached to a 1.0 mm-thick glass slide. The other one-sided release film of the adhesive sheet was peeled off, and mist was used. The meter HM-150 (Murakami Color Research Institute) measures the haze of the adhesive layer only.

The abbreviations in Tables 2 and 3 have the following meanings.

AA: Acrylic

AM: Acrylamide

BA: n-butyl acrylate

2EHA: 2-ethylhexyl acrylate

2EHMA: 2-ethylhexyl methacrylate

MA: methyl acrylate

HEA: 2-hydroxyethyl acrylate

HEMA: 2-hydroxyethyl methacrylate

ISTA: Isostearyl Acrylate

From the results in Table 3, the compositions of Examples 1 to 9 were obtained by including the crosslinking agent 1 or the crosslinking agent 2 represented by the general formula (1) or the crosslinking agent represented by the general formula (2). 3 As component (B), it is understandable that foaming can be suppressed under humid and hot conditions, and high adhesion and excellent durability and transparency can be achieved.

In contrast, it is understood that the compositions of Comparative Examples 1 to 6 do not contain any of the crosslinking agent represented by the general formula (1) and the crosslinking agent represented by the general formula (2) as (B). The components (that is, the cross-linking agent 4 and the cross-linking agent 5 used in Comparative Examples 1 to 6 do not have the structure represented by the general formula (1) or the general formula (2)), and therefore cannot be sufficiently reduced. Foaming. Further, Comparative Example 2 is an example in which an adhesive sheet for evaluation is attached to a substrate (polycarbonate). However, it can be understood that an adhesive layer using an adhesive composition containing a crosslinking agent 4 has a low adhesive force. In addition, it can be understood that the composition of Comparative Example 7 contains a polymer G having an acidic group, so that the non-corrosiveness of the conductive film is poor.

In addition, in Examples 1 to 9, the addition of (A) In addition to the component and the (B) component, 1 part by mass of the (C) component and 0.1 part by mass of the (D) component are further blended to prepare an adhesive composition, and when an adhesive sheet is produced using the adhesive composition, the same results as above are obtained. The obtained adhesive sheet is capable of suppressing foaming under humid and hot conditions, and has high adhesive force and excellent durability and transparency.

Claims (5)

An adhesive composition for a touch panel, comprising: (A) an acrylic polymer having a weight-average molecular weight of 100,000 or more and less than 800,000, and substantially containing no acidic group; and (B) cross-linking The agent is represented by the following general formula (1) or (2); the (A) acrylic polymer contains (a1) (meth) acrylic acid alkyl ester and (a2) hydroxyl-containing monomer The copolymer of a monomer component contains 0.04 parts by mass or more and 10 parts by mass or less of the (B) crosslinking agent with respect to 100 parts by mass of the acrylic polymer (A), (In the formula, R ^1A , R ^1B , and R ^1C are independent and are a group containing a group represented by the following general formula (3) and / or a group represented by the following general formula (4). R ^2A , R ^2B , R ^2C is a group represented ^by- (CH ₂ ) _6- ), (In the formula, R ^1A , R ^1B , and R ^1C are independent and are a group containing a group represented by the following general formula (3) and / or a group represented by the following general formula (4). R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E , and R ^3F are groups represented ^by- (CH ₂ ) _6- ), (Where x is an integer of 2 to 10 and m is an integer of 1 to 10), (In the formula, X is a single bond or -O-, y is an integer from 2 to 10 and n is an integer from 1 to 10). The adhesive composition for a touch panel according to item 1 of the scope of the patent application, wherein the monomer component contains: (a1) (meth) acrylic acid alkyl ester, at least 45% by mass and at most 99% by mass; The (a2) hydroxyl-containing monomer is 1% by mass to 40% by mass; and a monomer other than the components (a1) and (a2) and having one olefinic double bond in the molecule 0% to 15% by mass. The adhesive composition for a touch panel according to item 2 of the scope of patent application, wherein the monomer is a monomer other than the components (a1) and (a2) and has an olefinic double bond in the molecule, The monomer component further contains (a3) a nitrogen-containing monomer in an amount of 0.1 mass% to 7 mass%; and (a4) is a monomer other than the components (a1), (a2), and (a3) The monomer having one olefinic double bond in the molecule is 0% by mass or more and 10% by mass or less. Here, (a1) component + (a2) component + (a3) component + (a4) component = 100 quality%. An adhesive sheet is an adhesive composition for a touch panel according to any one of claims 1 to 3 on one or both sides of a support. A laminated body comprising a first substrate, a second substrate, and an adhesive layer obtained from the adhesive composition for a touch panel according to any one of claims 1 to 3; The 1 base material and the second base material are bonded together through the adhesive layer, and the first base material and the second base material each contain glass or resin.