TW201508041A - Optical adhesive composition, optical adhesive sheet, image display device and input/output device - Google Patents

Abstract

The objective of the present invention is to provide an optical adhesive composition capable of obtaining an adhesive layer with low dielectric constant and excellent adhesion, an optical adhesive sheet using the optical adhesive composition, and an image display device and an input/output device including the optical adhesive sheet. The present invention provides an optical adhesive composition comprising a (A) copolymer including a monomer mixture, wherein the monomer mixture comprises: (a1) 3 mass% or more and 39 mass% or less of an alkyl methacrylate monomer with an alkyl group with a carbon number of 10 or more and 18 or less, and (a2) 20 mass% or more and 97 mass% or less of an alkyl methacrylate monomer with an alkyl group with a carbon number of 1 or more and 10 or less, wherein, the summation of the component (a1) and the component (a2) is 45 mass% or more and 100 mass% or less.

Description

Optical adhesive composition, optical adhesive sheet, image display device, and output input device

The present invention relates to an optical adhesive composition, an optical adhesive sheet, an image display device, and an output input device.

In recent years, image display devices such as liquid crystal display devices and output input devices such as touch panels used in combination with image display devices have been widely used. In the manufacture of such an image display device or an output input device, an adhesive composition is used in the case of bonding the constituent members.

With the miniaturization of the electronic components constituting the image display device or the output input device, for example, high frequency noise generated in the circuit or charging of the dielectric body sandwiched by the conductor at the time of starting, in the electronic component The erroneous operation caused by the noise generated by the internal circuits contained in it can not be ignored. In particular, an adhesive layer formed of an adhesive composition containing an acrylic adhesive as a main component has a higher dielectric constant and is sometimes insulated when an adhesive composition having such a high specific dielectric ratio is used. The electrostatic capacity of the layer will become high, resulting in erroneous operation due to high frequency noise.

For example, Patent Document 1 discloses an optical adhesive sheet whose purpose is to prevent erroneous operation of an electrostatic capacitance type touch panel type input/output device.

Advanced technical literature Patent literature

Patent Document 1: International Publication WO2010/147047

The present invention provides an optical adhesive composition which can obtain an adhesive layer having a low dielectric constant and excellent adhesion, an optical adhesive sheet obtained by using the optical adhesive composition, and an image containing the optical adhesive sheet Display device and output input device.

In order to solve such a problem, the present inventors have found that the content of the methacrylate is adjusted in a copolymer of (a1) a monomer mixture containing an alkyl methacrylate having an alkyl group having 10 or more and 18 or less carbon atoms. Thus, by using the composition containing the copolymer, an adhesive sheet having a low dielectric constant and excellent adhesion can be obtained.

1. An optical adhesive composition according to one aspect of the present invention, which comprises a (A) copolymer containing a monomer mixture, the monomer mixture comprising: (a1) a methyl group having an alkyl group having 10 or more and 18 or less carbon atoms. 3% by mass or more and 39% by mass or less of the alkyl acrylate monomer; (a2) 20% by mass or more and 97% by mass or less of the alkyl methacrylate monomer having an alkyl group having 1 or more and 9 or less carbon atoms; In addition, the total of the component (a1) and the component (a2) is 45 mass% or more and 100 mass% or less.

2. The optical adhesive composition according to the above 1, wherein the (A) copolymer has a weight average molecular weight of 50,000 or more and 700,000 or less.

3. The optical adhesive composition according to the above 1 or 2, wherein the (A) copolymer has a glass transition temperature (Tg) of 0 ° C or less.

4. The optical adhesive composition according to any one of the above 1 to 3, wherein, in the monomer mixture, the content of the component (a2) relative to the content of the component (a1) may be 0.5 or more and 5 or less. .

The optical adhesive composition according to any one of the above 1 to 4, further comprising (a3) a hydroxyl group-containing monomer in an amount of 2% by mass or more and 30% by mass or less.

6. The optical adhesive composition according to the above 5, wherein the (a3) hydroxyl group-containing monomer is a hydroxyl group-containing alkyl methacrylate monomer.

In the optical adhesive composition according to any one of the above aspects, the monomer mixture may further contain (a4) a nitrogen atom-containing monomer in an amount of 0.1% by mass or more and 5% by mass or less.

In the optical adhesive composition according to any one of the above 1 to 7, the total amount of the methacrylate monomers in the monomer mixture may be 80% by mass or more and 100% by mass or less.

In the optical adhesive composition according to any one of the above aspects, the content of the (A) copolymer in the adhesive composition may be 70% by mass or more and 99.9% by mass or less.

In the optical adhesive composition according to any one of the above 1 to 9, the (A) copolymer may have a hydroxyl value of 15 or more and 150 or less.

In the optical adhesive composition according to any one of the above 1 to 10, the gel of the (A) copolymer may be 30% or more and 90% or less.

The optical adhesive composition according to any one of the above 1 to 11, wherein the (A) copolymer has a crosslinkable functional group and further contains (B) a crosslinking agent.

The optical adhesive composition according to the above 12, which may contain 0.01 parts by mass or more and 20 parts by mass or less of the above (B) crosslinking agent per 100 parts by mass of the copolymer (A).

14. The optical adhesive composition according to the above 12 or 13, wherein the crosslinking agent (B) is an isocyanate crosslinking agent.

The optical adhesive composition according to any one of the above 1 to 14, which can be used for bonding a member constituting a touch panel type input/output device or an image display device.

An optical adhesive sheet according to any one of the above 1 to 15, which is characterized in that the adhesive sheet for optical use according to any one of the above 1 to 15.

17. The optical adhesive sheet according to item 16 above, which has a dielectric constant of 4.0 or less at a ratio of 100 Hz.

An image display device according to one aspect of the invention, comprising the optical adhesive sheet according to the above 16 or 17.

An output input device according to one aspect of the invention, comprising the optical adhesive sheet according to the above 16 or 17.

The optical adhesive composition contains a (A) copolymer of a monomer mixture containing (a1) 3% by mass of an alkyl methacrylate monomer having an alkyl group having 10 or more and 18 or less carbon atoms. (a2) is 20% by mass or more and 97% by mass or less of the alkyl methacrylate monomer having an alkyl group having 1 or more and 9 or less carbon atoms; and the component (a1) and the component (a2) The total amount of the adhesive composition is 45 mass% or more and 100 mass% or less, whereby an adhesive layer having a low dielectric constant and excellent adhesion can be obtained by using the optical adhesive composition. Moreover, since the adhesive layer has excellent durability and excellent transparency, it can be suitably used for, for example, an image display device or an output input device.

10, 110‧‧‧ liquid crystal display device (LCD)

11, 15‧‧‧ polarizing plate

12, 14, 17‧‧ ‧ adhesive layer

13‧‧‧LCD panel

16‧‧‧Splash suppression film

18‧‧‧ITO layer

19‧‧‧Glass panel (touch panel)

20, 120‧‧‧ touch panel

30, 32‧‧‧Adhesive layer

100, 200, 300‧‧‧ touch panel type input input device

130‧‧‧ spacer layer

140‧‧‧ gap

Fig. 1 is a cross-sectional view showing the configuration of a first output input device (touch panel type input/output device) according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the configuration of a second output input device (touch panel type input/output device) according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view schematically showing the configuration of a known output input device (touch panel type output input device).

The invention will be described in detail below with reference to the drawings. In addition, in the present invention, "parts" means "parts by mass", "%" unless otherwise stated. Represents "% by mass".

1.1. Optical adhesive composition

1.1. (A) Copolymer

The optical adhesive composition according to one embodiment of the present invention contains the (A) copolymer of the monomer mixture (may be referred to simply as "(A) component in the present specification), and the monomer mixture contains: (a1) The alkyl methacrylate monomer having an alkyl group having 10 or more and 18 or less carbon atoms (may be referred to simply as "(a1) component in the present specification)) is 3% by mass or more and 39% by mass or less, and (a2) has carbon. The alkyl methacrylate monomer having an alkyl group number of 1 or more and 9 or less (may be referred to as "(a2) component in some cases in the present specification)) is 20% by mass or more and 97% by mass or less; and the component (a1) and The total of the components (a2) is 45 mass% or more and 100 mass% or less.

From the viewpoint of improving moisture and heat whitening resistance, the component (A) preferably has a functional group. In the present invention, the moist heat whitening property refers to a phenomenon in which the adhesive film is whitened (white turbid) when exposed to high temperature and high humidity conditions (for example, 60 ° C 95% RH) and then returned to room temperature. In addition, the functional group is a crosslinkable functional group which can form a crosslinked structure by reacting with the crosslinking agent (B) described later, and examples thereof include a hydroxyl group and an amine group.

Further, the component (A) preferably contains substantially no carboxyl group. In the present invention, the content of the carboxyl group-containing monomer in the monomer mixture is, for example, 0.1% by mass or less, and more specifically, the carboxyl group-free monomer is not used. A monomer constituting the aforementioned monomer mixture.

1.1.1. Monomer mixture

By using the optical adhesive composition of the present embodiment, an adhesive layer having excellent adhesion to a adherend (especially glass), a low dielectric constant, and excellent durability is obtained. From this point of view, the component (A) is more It is preferably a copolymer containing a monomer composition of the component (a1), the component (a2), the component (a3) and the component (a4) to be described later, and more preferably a methacrylic polymer.

In the present invention, the "methacrylic polymer" means a polymer containing at least one selected from the group consisting of methacrylic acid, methacrylic acid salt and methacrylic acid in an amount of 50% by mass or more.

Further, in the present invention, the term "methacrylate monomer" includes a methacrylate monomer having a functional group (for example, a hydroxyl group, an amine group, etc.) in addition to the alkyl methacrylate monomer. Therefore, for example, the "alkyl methacrylate monomer" also includes a hydroxyl group-containing methacrylate monomer which can be used as a component (a1), a component (a2), and a component (a3) to be described later.

1.1.1-1. (a1) ingredients

The component (a1) can help adjust the Tg of the component (A) to 0 ° C or lower.

When the component (a1) exceeds 39% by mass of the monomer mixture, the adhesive layer obtained by using the optical adhesive composition of the present embodiment has a low adhesive force to the adherend, and sufficient reliability cannot be obtained. On the other hand, if it is less than 3% by mass, the glass transition temperature (Tg) of the component (A) may become high, and the adhesive layer may become too hard. The content of the component (a1) in the monomer mixture is preferably 3% by mass or more and 39% by mass or less, and more preferably 10% by mass or more, from the viewpoint of excellent durability and appropriate hardness. 39% by mass or less, more preferably 20% by mass or more and 39% by mass or less.

The component (a1) may, for example, be an alkyl methacrylate monomer having a linear alkyl group, a branched alkyl group or a cyclic alkyl group, wherein the Tg of the component (A) is lowered, and the monomer mixture is The obtained adhesive layer is preferably a linear or branched alkyl group from the viewpoint of imparting flexibility. Further, the alkyl group contained in the component (a1) is more preferably an alkyl methacrylate monomer having a linear alkyl group having 10 or more and 16 or less carbon atoms.

More specifically, the component (a1) may be n-decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate or n-hexadecyl methacrylate. And an alkyl methacrylate monomer having a linear alkyl group, such as stearyl methacrylate, may be used alone or in combination of two or more.

1.1.1-2. (a2) ingredients

The component (a2) can contribute to the adhesion and durability of the adhesive layer obtained by using the optical adhesive composition of the present embodiment.

When the amount of the component (a2) exceeds 97% by mass of the monomer mixture, the adhesive layer obtained by using the optical adhesive composition of the present embodiment may be too hard to obtain sufficient adhesion to the adherend, and On the other hand, if it is less than 20% by mass, the durability may be poor. The content of the component (a2) in the monomer mixture is preferably 30% by mass or more and 86.8 mass% or less, more preferably 30% by mass or more and 74.7% by mass or less, from the viewpoint of more excellent durability and more appropriate hardness. .

The component (a2) may be, for example, a linear alkyl group or a branched chain. An alkyl methacrylate monomer, wherein a linear or branched carbon number of 5 or more and 9 or less is preferable from the viewpoint of adjusting the Tg of the component (A) and the adhesion of the obtained adhesive. Alkyl group.

More specifically, the component (a2) may, for example, be methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate or n-octyl methacrylate. An alkyl methacrylate monomer having a linear alkyl group such as an ester or n-decyl methacrylate;

Isopropyl methacrylate, isobutyl methacrylate, tributyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, etc. The monomer may be used alone or in combination of two or more.

The content of the component (a2) relative to the content of the component (a1) in the monomer mixture is preferably 0.5 or more and 5 or less, more preferably 0.8 or more, from the viewpoint of adjusting the Tg of the copolymer to 0 ° C or lower. the following. From the same viewpoint, the total of the component (a1) and the component (a2) is generally 45 mass% or more and 100 mass% or less, preferably 60 mass% or more and 98 mass% or less.

1.1.1-3. (a3) ingredients

The monomer mixture may further contain (a3) a hydroxyl group-containing monomer from the viewpoint of improving the whitening resistance of the pressure-sensitive adhesive layer obtained by using the optical pressure-sensitive adhesive composition of the present embodiment (also referred to as "( A3) Component") 2% by mass or more and 30% by mass or less.

The component (a3) is a crosslinkable structure which can be bridged with the (B) crosslinking agent described later. The ingredients. When the component (a3) exceeds 30% by mass of the monomer mixture, the specific dielectric constant of the adhesive layer may be too high. On the other hand, if it is less than 2% by mass, the adhesive layer may be whitened. Poor sex. The content of the component (a3) in the monomer mixture is preferably 3% by mass or more and 20% by mass or less, more preferably, the whitening property of the pressure-sensitive adhesive layer is better and the dielectric constant of the pressure-sensitive adhesive layer is adjusted. It is 5 mass% or more and 15 mass% or less.

Examples of the component (a3) include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-chloropropyl acrylate, and 2-acrylic acid 2- An alkyl acrylate monomer such as hydroxy-3-phenoxypropyl ester; an alkylene glycol acrylate such as ethylene glycol acrylate, acrylic acid polyethylene glycol, acrylic propylene glycol or acrylic polypropylene glycol; 2-hydroxyethyl methacrylate 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-methacrylate An alkyl methacrylate monomer such as phenoxypropyl ester; or an alkylene glycol methacrylate such as ethylene glycol methacrylate, polyethylene glycol methacrylate, propylene glycol methacrylate or polypropylene glycol methacrylate. Alternatively, one type or a combination of two or more types may be used alone. Among them, the (a3) component is preferably a hydroxy group-containing methacrylate monomer from the viewpoint of compatibility with the component (a1) and the component (a2).

1.1.1-4. (a4) ingredients

The monomer mixture may further contain (a4) a monomer containing a nitrogen atom (also referred to as "(a4) component)) in an amount of 0.1% by mass or more from the viewpoint of imparting a cohesive force to the optical adhesive composition of the present embodiment. 5 mass% or less. The nitrogen atom contained in the component (a4) is bonded to a hydrogen atom existing in the adhesive composition, and the hydrogen atom participates in the formation of a hydrogen bond in the adhesive composition, whereby a high cohesive force can be found. The content of the component (a4) in the monomer composition is preferably 0.2% by mass or more and 4% by mass or less, and more preferably 0.3% by mass or more and 3% by mass or less, from the viewpoint of the higher cohesive force.

The component (a4) is preferably a monomer containing, for example, a guanamine group or an amine group. The component (a4) is a monomer containing a mercaptoamine group or an amine group, whereby the reaction of the component (A) with the component (B) described later and the hydrogen bonding to the nitrogen atom constituting the amidino group or the amine group can be promoted. The atom participates in the formation of hydrogen bonds in the adhesive composition, whereby higher agglutination can be found. Further, when the component (a4) is a ring-shaped nitrogen atom-containing monomer, the content of the monomer having a cyclic nitrogen-containing atom is preferably less than 0.5% by mass (for example, 0) from the viewpoint of exhibiting an appropriate cohesive force. The mass% or more is less than 0.5% by mass), and is more than 0.1% by mass (for example, 0% by mass or more and less than 0.1% by mass).

The (a4) component, for example, an amine group-containing monomer may, for example, be N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate or methacrylic acid N. , N-diethylaminoethyl ester.

Examples of the mercapto group-containing monomer include N,N-dimethylaminopropyl acrylamide, N,N'-dimethyl decylamine, N,N'-diethyl acrylamide, N,N'-dimethylaminoethyl acrylamide, N,N'-dimethylaminopropyl acrylamide, N-isopropyl acrylamide, trioctyl (meth) propylene Guanamine, diacetone acrylamide, n-propyl (meth) acrylamide, N-hexyl (meth) acrylamide, (meth) acrylamide.

The monomer containing a nitrogen-containing heterocyclic ring is, for example, pentamethylpiperidinyl (methyl) propyl Ethyl ester, vinyl pyridine, vinyl pyrrolidone, acryloyl morpholine, ethylene caprolactam.

These may be used alone or in combination of two or more.

The component (a4) is preferably a monomer having a (meth)acryl fluorenyl group from the viewpoint of compatibility of the component (a1), the component (a2), and the component (a3).

In the optical adhesive composition of the present embodiment, The adhesive layer obtained by using the optical adhesive composition can achieve a low specific dielectric ratio, excellent durability, and good adhesion to an adherend (especially glass) for obtaining the (A) component. In the monomer mixture, the total amount of the component (a1), the component (a2), the component (a3), and the component (a4) may be 80% by mass or more and 100% by mass or less, preferably 90% by mass or more and 100% by mass. %the following.

In the optical adhesive composition of the present embodiment, the methacrylate in the monomer mixture can be obtained from the viewpoint of achieving a low specific dielectric ratio, excellent adhesion, durability, and a lower specific dielectric ratio. The total of the monomers is preferably 80% by mass or more and 100% by mass or less, more preferably 85% by mass or more and 99.9% by mass or less, and still more preferably 90% by mass or more and 99.9% by mass or less.

For example, in the optical adhesive composition of the present embodiment, the (a1) component and the (a2) component are the monomer mixture from the viewpoint of further reducing the dielectric constant and achieving more excellent durability. And the total of the components (a3) is 79.9 mass% or more and 99 mass% or less, and it is preferable that the component (a1), the component (a2), and the component (a3) are methacrylate monomers.

1.1.1-5. (a5) ingredients

The monomer mixture may contain the (a1) component, the component (a2), the component (a3), and the copolymerizable monomer other than the component (a4) as the component (a5). The component (a5) may, for example, be an alkyl acrylate monomer having an alkyl group having 1 or more and 18 or less carbon atoms, or a carboxyethyl acrylate; or benzyl (meth) acrylate, 2-naphthyl acrylate or phenoxy acrylate. (meth) acrylate monomer having an aromatic ring group such as ester; dicyclopentenyl oxyethyl acrylate, glycidyl (meth) acrylate, tetrahydrofuran methyl methacrylate, etc. having an ether group Acrylate; styrene monomer such as styrene, α-methylstyrene, o-methylstyrene or p-methylstyrene; vinyl carboxylate such as vinyl acetate; containing vinyl (methyl) One type or a combination of two or more types of the propylene group-based macromonomer may be used alone. The content of the component (a5) in the monomer composition is preferably 0% by mass or more and 20% by mass or less, more preferably 0% by mass or more and 10% by mass or less.

1.1.2.Tg

In the optical adhesive composition of the present embodiment, the adhesive layer obtained by using the optical adhesive composition is more excellent in step followability, and the durability of the adhesive layer and the adhesive layer can be improved. From the viewpoint of the adhesion of the adherend, the Tg of the component (A) is preferably 0 ° C or lower, more preferably from -40 ° C to 10 ° C. Further, in the present invention, the Tg of the component (A) is a value calculated by the following formula (1) (FOX formula).

1/Tg _A = W _a1 /Tg _a1 +W _a2 /Tg _a2 +W _a3 /Tg _a3 +W _a4 /Tg _a4 +W _a5 /Tg _a5 (1) (wherein Tg _A represents (A) component The glass transition temperature (K), Tg _a1 , Tg _a2 , and Tg _a3 respectively represent homopolymerization modulated by the (a1) component, the (a2) component, the (a3) component, (a4), and (a5) constituting the monomer. The glass transition temperature (Tg(K)) of the object, W _a1 , W _a2 , W _a3 , W _a4 , and W _a5 respectively represent the (a1) component and the (a2) component of the constituent monomer contained in the component (A). (a3) component, (a4) component, and (a5) component by weight.)

Further, since Tg _A is calculated as the absolute temperature (K) according to the above formula (1), it can be converted to Celsius temperature (°C) as needed.

Further, the glass transition temperature of the homopolymer prepared by a representative monomer is shown in Table 1 below, and more specifically, for example, in Polymer Handbook Third Edition (Polymer Handbook Third Edition, Wiley-Interscience, 2003). Wait.

1.1.3. Weight average molecular weight

The weight average molecular weight (Mw) of the component (A) is 50,000 or more and 700,000 or less. When the weight average molecular weight of the component (A) is less than 50,000, the durability is inferior. On the other hand, if it exceeds 700,000, the weight average molecular weight of the component (A) is preferably 100,000 or more from the viewpoint of poor workability at the time of coating. 600,000 or less, more preferably 150,000 or more and 400,000 or less. Here, the weight average molecular weight of the component (A) is a GPC (colloidal permeation chromatography), and the weight average molecular weight (Mw) in terms of standard polystyrene is determined under the following conditions.

<GPC measurement conditions>

Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC column structure: The following 5 series of pipe columns (all manufactured by Tosoh)

(i) TSK-GEL HXL-H (protective column)

(ii) TSK-GEL G7000HXL

(iii) TSK-GEL GMHXL

(iv) TSK-GEL GMHXL

(v)TSK-GEL G2500HXL

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

Mobile phase solvent: tetrahydrofuran

Flow rate: 1.0cm ³ /min

Column temperature: 40 ° C

1.1.4. Hydroxyl price

In the present invention, the hydroxyl value means the number of mg of potassium hydroxide (KOH) required for the acetylation of the hydroxyl group contained in 1 g of the sample. The hydroxyl value can be calculated by the following method.

In the present invention, the hydroxyl value of the polymer is based on the molecular weight (M) of the hydroxyl group-containing monomer used for the copolymerization, the blending amount (Y mass%) of the hydroxyl group, and the value calculated according to the following formula (2). . The hydroxyl value of the polymer (mgKOH)=Y/M×561‧‧‧(2)

The hydroxyl value of the (A) copolymer is preferably 15 or more and 150 or less, more preferably 20 or more and 150 or less, still more preferably 20 or more and 130 or less. When the hydroxyl value of the (A) copolymer exceeds 150, the specific dielectric constant of the adhesive layer obtained by using the optical adhesive composition of the present embodiment becomes too high, and if it is less than 20, Sometimes the adhesive layer is poor in whitening resistance.

1.1.5. Content in the adhesive composition

The content of the component (A) in the optical adhesive composition of the present embodiment may be 70% by mass or more and 99.9% by mass or less, preferably 80% by mass or more and 99.9% by mass or less, and more preferably 95% by mass or less. The mass% or more is 99.9% by mass or less.

1.1.6. Gel rate

In addition, the optical adhesive composition of the present embodiment can be improved from the viewpoint of the durability of the adhesive layer obtained by using the optical adhesive composition of the present embodiment and the adhesion to the adherend. The gel fraction is preferably 30% or more and 90% or less, more preferably 50% or more and 85% or less.

In the optical adhesive composition of the present embodiment, the gel fraction is, for example, the type and amount of the component (a3) and the component (a4) which can be used in preparing the adhesive composition. The amount of the crosslinking agent of the component (B) and the amount of use thereof were adjusted. Further, the above gel fraction is obtained by taking 0.1 g (dry weight 1) of the crosslinked adhesive in a vial on a dry weight, further adding 30 cc of ethyl acetate to the vial and shaking for 24 hours, The contents of the vial were filtered through a mesh of 200 mesh stainless steel, and the residue on the metal mesh was dried at 100 ° C for 2 hours and the dry weight (dry weight 2) was measured, and the following formula (3) was determined.

Gel fraction (%) = (dry weight 2) / (dry weight 1) × 100‧‧‧(3)

1.1.7. Aggregation method

The polymerization method of the component (A) is not particularly limited, and polymerization can be carried out by a known method such as solution polymerization, emulsion polymerization or suspension polymerization. However, when the pressure-sensitive adhesive composition of the present invention is produced by using a mixture of the copolymers obtained by polymerization, the treatment step is carried out. From the standpoint of being simpler and capable of being carried out for a short period of time, it is preferred to carry out the polymerization by solution polymerization.

The solution polymerization is generally carried out by adding a specific organic solvent, each monomer, a polymerization initiator, and a chain transfer agent as needed in a polymerization tank, and heating is carried out while stirring at a reflux temperature of a nitrogen gas or an organic solvent. Hours.

Further, at this time, at least a part of the organic solvent, the monomer, and/or the polymerization initiator may be added one by one. The organic solvent may, for example, be benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene or o-xylene. Aromatic hydrocarbons such as meta-xylene, p-xylene, tetrahydronaphthalene, decalin, aromatic naphtha, etc.; for example, n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentane An aliphatic or alicyclic hydrocarbon such as ethyl, mineral oil, petroleum naphtha, turpentine; for example, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butyl acetate An ester of oxyethyl ester, 3-methoxybutyl acetate, methyl benzoate or the like; for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methylcyclohexane Ketones such as ketones; for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, etc. A glycol ether; for example, an alcohol such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, a second butyl alcohol or a third butyl alcohol. These organic solvents can be used alone or in combination of two or more.

In the organic solvent for polymerization, when the component (A) is polymerized, it is preferred to use an organic solvent such as an ester or a ketone which is less likely to cause chain transfer during the polymerization reaction. In particular, the solubility of the component (A) and the polymerization reaction are easy. From the viewpoint of sex, etc., it is preferred to use ethyl acetate, methyl ethyl ketone, acetone or the like.

As the polymerization initiator, an organic peroxide, an azo compound or the like which can be used in general solution polymerization can be used. Examples of such organic peroxides include tert-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzammonium peroxide, lauricium peroxide, and hexanyl peroxide. , diisopropyl peroxycarbonate, di-2-ethylhexyl peroxycarbonate, tert-butyl peroxypivalate, 2,2-bis(4,4-di-peroxide tert-butyl ring Hexyl)propane, 2,2-bis(4,4-di-peroxide-dipentylcyclohexyl)propane, 2,2-bis(4,4-di-peroxide-distributed trioctylcyclohexyl)propane, 2,2-double (4,4-di-over Oxidation of α-isopropylphenylcyclohexyl)propane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)butane, 2,2-bis(4,4-di-peroxidation The third octylcyclohexyl)butane or the like, and the azo compound may, for example, be 2,2'-azobis-isobutyronitrile or 2,2'-azobis-2,4-dimethylvaleronitrile. 2,2'-Azobis-4-methoxy-2,4-dimethylvaleronitrile and the like.

Among these polymerization initiators, a polymerization initiator which does not cause a graft reaction in the polymerization reaction of the component (A) is preferred, and an azo system is particularly preferred. The amount thereof is generally 0.01 parts by mass or more and 2 parts by mass or less, preferably 0.05 parts by mass or more and 1.0 part by mass or less based on 100 parts by mass of the total of the monomers.

Examples of the chain transfer agent include cyanoacetic acid; alkyl esters having a carbon number of 1 or more and 8 or less of cyanoacetic acid; bromoacetic acid; alkyl esters having a carbon number of 1 or more and 8 or less of bromoacetic acid; anthracene, phenanthrene, anthracene, and 9-benzene. An aromatic compound such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene, etc.; a benzoquinone derivative such as 2,3,5,6-tetramethyl-p-benzoquinone; a borane derivative such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2 , halogenated hydrocarbons such as 2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, 3-chloro-1-propane; aldehydes such as trichloroacetaldehyde and furaldehyde; carbon An alkyl mercaptan having a number of 1 or more and 18 or less; an aromatic mercaptan such as thiophenol or toluene mercaptan; an alkyl ester having a carbon number of 1 or more and 10 or less of mercaptoacetic acid or mercaptoacetic acid; and a carbon number of 1 or more and 12 or less Hydroxyalkyl thiols; terpenes such as terpenes and terpinolene.

The polymerization temperature of the component (A) is generally about 30 ° C or more and 180 Below °C, it is preferably 40 ° C or more and 150 ° C or less, and more preferably 50 ° C or more and 90 ° C or less. Further, when the unreacted monomer is contained in the polymer obtained by the solution polymerization method or the like, it may be purified by a reprecipitation method such as methanol in order to remove the monomer.

1.2. (B) Crosslinker

In the optical adhesive composition of the present embodiment, the component (A) has a crosslinkable functional group, and may further contain (B) a crosslinking agent (may also be referred to simply as "(B) component)". The (B) component reacts with the component (A) to form a crosslinked structure, and the adhesive layer containing the crosslinked structure is excellent in durability and excellent in adhesion to a adherend (especially glass).

The component (B) may be an isocyanate crosslinking agent. The component (B) is an isocyanate-based crosslinking agent, whereby a crosslinking structure can be formed by reacting with, for example, a hydroxyl group contained in the component (A).

In the optical adhesive composition of the present embodiment, the component (B) is not particularly limited as long as it can be crosslinked with the component (A) at normal temperature or under heating, and is, for example, xylylene diisocyanate. , tolyl diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, etc. An isocyanate monomer or an isocyanate compound or a trimeric isocyanate which is added to an alcohol compound having two or more valences such as trimethylolpropane or the like.

Further, polyether polyols or polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols are also known. An urethane prepolymer type isocyanate or the like which adds an isocyanate compound to an isocyanate compound. Among these, hexamethylene diisocyanate, tolyl diisocyanate, and the like are preferably used.

The content of the component (B) in the optical adhesive composition of the present embodiment is more than 100 parts by mass of the component (A) from the viewpoint of achieving a specific gel fraction (for example, 30% or more and 90% or less). It is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less.

1.3. Other ingredients

The optical adhesive composition of the present embodiment may further contain components other than the components (A) and (B) as needed. For example, in the optical adhesive composition of the present embodiment, (C) a decane coupling agent (hereinafter sometimes referred to simply as "(C) component") or an ion may be blended in a range that does not impair the effects of the present invention. Compounds, antioxidants, UV absorbers, tackifiers, plasticizers, etc.

1.3.1. (C) decane coupling agent

The optical adhesive composition of the present embodiment contains the component (C), and when the adhesive composition for an optical body of the present embodiment is used to form an adhesive layer on the surface of the adherend, the adherend can be well retained. Then. The component (C) may, for example, be a fluorene compound containing a polymerizable unsaturated group such as vinyltrimethoxydecane, vinyltriethoxydecane, or methacryloxypropyltrimethoxydecane; Oxypropoxypropyltrimethoxydecane, 3- An epoxy structure oxime compound such as glycidoxypropylmethyldimethoxydecane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane; 3-aminopropyltrimethyl Oxydecane, N-(2-aminoethyl) 3-aminopropyltrimethoxydecane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane And an amine group-containing hydrazine compound; and 3-chloropropyltrimethoxy decane; an oligomer type decane coupling agent, etc., wherein, from the viewpoint of not easily peeling off in a hot and humid environment, it is preferred to have (A) A decane coupling agent having a functional group reactive with a functional group contained in the component.

In the optical adhesive composition of the present embodiment, the content of the component (C) is 0.1% by mass based on the optical adhesive composition of the present embodiment, from the viewpoint of adhering well to the adherend. The above 5 mass% or less is preferably 0.2 mass% or more and 1 mass% or less.

1.4. Manufacture of adhesive composition

The optical adhesive composition of the present embodiment is generally prepared by mixing the above-mentioned (A) component and (B) component and optionally any component as needed or in an arbitrary order. Further, when the component (A) and the component (B) are mixed, when the component (A) is prepared by solution polymerization, the component (B) may be added to the solution containing the component (A) after completion of the polymerization, and the block may be added. When the component (A) is prepared by polymerization, it is difficult to uniformly mix after the completion of the polymerization. Therefore, it is preferred to add the component (B) in the middle of the polymerization and mix.

1.5. Use

The optical adhesive composition of the present embodiment can be used for optics The fit of the components.

The optical member to be bonded to the optical adhesive composition of the present embodiment includes, for example, a polarizing film (polarizing plate), a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and a light diffusion film. And the optical film selected by the group formed by the hard coat film. Further, examples of the adherend include a metal layer such as an ITO layer, and a substrate made of glass or plastic. Further, the adhesive layer obtained by using the optical adhesive composition of the present embodiment can be suitably used for bonding to glass from the viewpoint of excellent adhesion to glass.

Moreover, the adhesive layer obtained by using the optical adhesive composition of the present embodiment can be suitably used for a touch panel type input/output device or image from the viewpoint of a low dielectric constant, excellent adhesion, and durability. The bonding of the optical components of the display device.

1.6. Adhesive sheet (adhesive layer)

An adhesive sheet according to an embodiment of the present invention has an adhesive layer formed of the optical adhesive composition of the present embodiment. The adhesive layer can be produced, for example, by forming into a film shape and removing the solvent.

More specifically, the adhesive sheet of the present embodiment is obtained by, for example, applying the optical adhesive composition of the present embodiment to a separator (release film) to form a film, and then removing the solvent. More specifically, the optical adhesive composition of the present embodiment is applied to a substrate by a gravure coater, a wire bar coater, an air knife coater, a roll coater or the like, and the applied adhesive is applied. The composition is dried, and the adhesive of the embodiment can be produced. sheet. By attaching the adhesive sheet (adhesive layer) of the present embodiment between the adherend and the optical member, the adherend can be bonded to the optical member.

The adhesive sheet of the present embodiment has a dielectric constant of 4.0 or less (generally 1 or more and 4.0 or less), preferably 3.7 or less (1 or more and 3.7 or less), more preferably 3.5 or less (1 or more and 3.5 or less).

The thickness of the adhesive sheet (adhesive layer) of the present embodiment is generally 1 μm or more and 250 μm or less, preferably 10 μm or more and 180 μm or less.

1.7. Other embodiments

(1) The optical adhesive composition according to one embodiment of the present invention contains a (A) copolymer of a monomer mixture containing (a1) a methyl group having an alkyl group having 10 or more and 18 or less carbon atoms. The alkyl acrylate monomer is 3% by mass or more and 39% by mass or less; and the weight average molecular weight of the (A) copolymer is 50,000 or more and 700,000 or less.

(2) The optical adhesive composition according to the above (1), wherein the glass transition temperature (Tg) is 0 ° C or lower.

(A) The (A) copolymer may further contain (a2) an alkyl methacrylate having an alkyl group having 1 or more and 9 or less carbon atoms, in the optical adhesive composition according to the above (1) or (2). The ester monomer is 20% by mass or more and 97% by mass or less.

(4) The optical adhesive composition according to one embodiment of the present invention contains the (A) copolymer of the monomer mixture containing (a1) methacrylic acid having an alkyl group having 10 or more and 18 or less carbon atoms. Alkyl ester The body 3% by mass or more and 39% by mass or less; and the glass transition temperature of the (A) copolymer is 0 ° C or lower.

(5) The optical adhesive composition according to the above (4), wherein the (A) copolymer has a weight average molecular weight of 50,000 or more and 700,000 or less.

(A) The (A) copolymer further contains (a2) an alkyl methacrylate having an alkyl group having 1 or more and 9 or less carbon atoms, in the optical adhesive composition according to the above (4) or (5). The monomer is 20% by mass or more and 97% by mass or less.

1.8. Effect

The optical adhesive composition of the present embodiment contains a (A) copolymer of a monomer mixture containing (a1) an alkyl methacrylate monomer having an alkyl group having 10 or more and 18 or less carbon atoms. 3% by mass or more and 39% by mass or less, (a2) an alkyl methacrylate monomer having an alkyl group having 1 or more and 9 or less carbon atoms, 20 or less and 97% by mass or less; whereby the component (a1) and (a1) are derived from The a2 alkyl methacrylate of the component, and the adhesive layer obtained by using the optical adhesive composition has a low dielectric constant and excellent adhesion and durability. Therefore, the adhesive layer can be suitably used for, for example, an image display device or an output input device.

1.8.1. Composition of well-known output input devices

In order to more specifically explain the effects of the optical adhesive composition of the present embodiment, a configuration of a known output input device will be described. Fig. 3 is a cross-sectional view schematically showing the configuration of a known output input device (touch panel type output input device 200). The touch panel type output input device 200 includes a liquid crystal display device (LCD) 110 and a touch panel portion 120. The spacer layer 130 is provided at the end between the LCD 110 and the touch panel portion 120, so that a gap 140 is formed between the spacer layers 130 at both ends.

In recent years, high contrast of displays of touch panel type input and output devices has been demanded. In order to achieve high contrast, for example, a method of filling a gap between the image display portion of the gap and the touch sensor (the gap 140 in FIG. 3) with a transparent material such as an adhesive is used. Thereby, reflection or refraction of light between the respective interfaces can be suppressed, and as a result, high contrast can be achieved.

However, when the gap 140 in FIG. 3 is filled with an adhesive or the like and the member is bonded, charging of high-frequency noise or components generated from the internal circuit of the device is caused, and erroneous operation may occur in the touch sensor. In a touch panel type input/output device in which a gap is formed between a video display portion and a touch sensor (especially a capacitive touch sensor), the specific dielectric constant of the air layer due to the gap is 1 The gap formed by the air layer blocks noise, thereby preventing erroneous operation. On the other hand, in order to fill a gap between the image display unit and the touch sensor and use a transparent resin (for example, an acrylic adhesive having a dielectric constant of 4 or more) as a filling agent, high-frequency noise is transmitted to the touch. The sensor sometimes produces incorrect operation. In addition, the LCD 110 and the touch panel portion 120 are insufficient due to the gap 140.

In view of such an ins and outs, in the touch panel type input/output device, it is preferable to use an adhesive layer having a lower dielectric constant and excellent adhesion, and fill the gap between the image display portion and the touch sensor.

1.8.2. Effect of the invention

On the other hand, according to the optical adhesive composition of the present embodiment, an adhesive layer having a lower dielectric constant and excellent adhesion can be obtained by using the optical adhesive composition. Moreover, the erroneous operation of the touch sensor due to the high specific dielectric ratio of the adhesive layer can be prevented. In the output/output device 300 of Fig. 2, which will be described later, the void 140 of Fig. 2 is filled with the optical adhesive composition of the present embodiment having excellent adhesion, and the specific dielectric constant is 4.0 or less. The agent layer 32 is disposed in the gap 140, thereby preventing erroneous operation of the touch sensor. Moreover, since the adhesive layer 32 obtained by using the optical adhesive composition of the present embodiment is excellent in adhesion, the adhesive layer 32 is disposed in the gap 140, and the LCD 110 and the touch panel portion 120 can be reliably followed. .

For example, in the touch panel type output input device (first output input device) 100 of the present embodiment shown in FIG. 1, an adhesive layer 30 is provided between the LCD 10 and the touch panel unit 20, because the adhesive is used. Since the layer 30 is formed of the optical adhesive composition of the present embodiment, the specific dielectric ratio is as low as 4.0 or less, so that the error of the touch sensor due to the high specific dielectric ratio of the adhesive layer can be prevented. Since it is excellent in adhesion, it is possible to reliably follow the LCD 10 and the touch panel portion 20.

2. Image display device and output input device

An image display device according to an embodiment of the present invention includes an adhesive layer obtained by using the optical adhesive composition of the present embodiment. This embodiment The image display device of the state is, for example, a liquid crystal display device.

Further, an output input device according to an embodiment of the present invention includes an adhesive layer obtained by using the optical adhesive composition of the present embodiment. In this case, the output input device may be, for example, a capacitive touch panel type input/output device.

2.1. The first output input device

The touch panel type output input device (first output input device) 100 of the present embodiment shown in Fig. 1 will be described in detail below.

Fig. 1 is a cross-sectional view schematically showing the configuration of an input/output device (touch panel type output input device 100) according to an embodiment of the present invention. The touch panel type output input device 100 of the present embodiment includes a liquid crystal display device (LCD) 10, a touch panel portion 20, and an adhesive layer 30 disposed between the LCD 10 and the touch panel portion 20. The adhesive layer 30 is followed by the LCD 10 and the touch panel portion 20.

In the adhesive layer 30, for example, the optical adhesive composition of the present embodiment is applied to the surface of a separator film (not shown), and the obtained adhesive sheet is peeled off from the separation film by removing the solvent, and is placed on the LCD 10 and touched. Between the control panel 20.

As shown in Fig. 1, the LCD 10 is formed by sequentially laminating a polarizing plate 11, an adhesive layer 12, a liquid crystal panel 13, an adhesive layer 14, and a polarizing plate 15. The adhesive layer 12 is followed by the polarizing plate 11 and the liquid crystal panel 13, and the adhesive layer 14 is followed by the liquid crystal panel 13 and the polarizing plate 15.

Moreover, as shown in FIG. 1, the touch panel unit 20 is sequentially The laminated splash suppression film 16, the adhesive layer 17, the ITO layer 18, and the glass panel 19 are comprised. The adhesive layer 17 is followed by the splash suppressing film 16 and the ITO layer 18.

The adhesive layers 12, 14, and 17 are the same as the adhesive layer 30, and are manufactured using the optical adhesive composition of the present embodiment. The adhesive layers 12, 14, 17, and 30 obtained by using the optical adhesive composition of the present embodiment are excellent in adhesion, so that the adherends can be reliably adhered to each other. Moreover, the adhesive layers 12, 14, 17, 30 have a low dielectric constant, thereby preventing erroneous operation of the touch sensor.

2.2. 2nd output input device

Fig. 2 is a cross-sectional view schematically showing the configuration of a second output input device (touch panel type input/output device) 300 according to an embodiment of the present invention. The touch panel type output input device 300 includes a liquid crystal display device (LCD) 110 and a touch panel unit 120, similarly to the output input device 200 of FIG. The spacer layer 130 is provided at the end between the LCD 110 and the touch panel portion 120, so that a gap 140 is formed between the spacer layers 130 at both ends.

The adhesive layer 32 is disposed in the gap 140, and then the LCD 110 and the touch panel portion 120. The specific dielectric ratio of the adhesive layer 32 is 4.0 or less. In the touch panel type input/output device 300 of FIG. 2, the gap 140 of FIG. 3 is filled by using the optical adhesive composition of the present embodiment, and the adhesive layer 32 is placed in the gap 140, and the LCD 110 and the touch are attached. The control panel unit 120 is obtained. In the touch panel type output input device 300, the adhesive layer 32 having a dielectric constant of 4.0 or less is provided in the gap 140, so that the erroneous operation of the touch sensor can be prevented.

Moreover, since the adhesive layer 32 obtained by using the optical adhesive composition of the present embodiment is excellent in adhesion, the adhesive layer 32 is disposed in the gap 140, and the LCD 110 and the touch panel portion 120 can be reliably followed. .

Example

3. Embodiment

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

3.1. Modulation of component (A)

3.1.1. Manufacture of Polymer 1

80 parts by mass of ethyl acetate as a solvent and 35 parts by mass of lauryl methacrylate as a monomer component in a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel, and a stirring device, and methacrylic acid 2 44 parts by mass of ethylhexyl ester, 20 parts by mass of hydroxyethyl methacrylate, and 1 part by mass of acrylamide, and the temperature of the monomer composition solution in the reaction vessel after refluxing for 1 hour under nitrogen at room temperature The temperature was raised to 80 ° C, and 0.2 parts by mass of 2,2'-azobisisobutyronitrile was added under stirring. The polymerization was carried out for 10 hours in a nitrogen stream to obtain a solution of a copolymer (polymer 1) having a weight average molecular weight of 200,000. Further, the Tg of the polymer 1 and the hydroxyl value are shown in Table 2.

3.1.2. Manufacture of polymers 2 to 6, 10 to 17, 19

By using a monomer mixture of the compositions shown in Table 2, respectively The solutions of the polymers 2 to 6, 10 to 17, 19 were respectively obtained by the methods described in the above Production Example 1. The weight average molecular weight, Tg and hydroxyl value of the polymers 2 to 6, 10 to 17, 19 and the polymers 7 to 9 and 18 described later are shown in Table 2.

3.1.3. Manufacture of polymer 7

In the method of the above Production Example 1, the polymer 7 was obtained by the method described in Production Example 1, except that the 2,2'-azobisisobutyronitrile of the polymerization initiator was changed to 0.3 parts by mass.

3.1.4. Manufacture of polymer 8

In the method of the above Production Example 1, the polymer 8 was obtained by the method described in Production Example 1, except that 2,2'-azobisisobutyronitrile as a polymerization initiator was changed to 0.12 part by mass.

3.1.5. Manufacture of polymer 9

In the method described in the above Production Example 1, the polymer 8 was obtained by the method described in Production Example 1, except that 2,2'-azobisisobutyronitrile as a polymerization initiator was changed to 0.08 part by mass.

3.1.6. Manufacture of polymer 18

In the method of the above Production Example 1, 2,2'-azobisisobutyronitrile as a polymerization initiator was changed to 0.08 parts by mass, and the monomer component of lauryl methacrylate was changed to 99 parts by mass, and acrylic acid 4 was used. The polymer 18 was obtained by the method described in Production Example 1 except that the hydroxybutyl ester was changed to 1 part by mass.

3.2. Modulation of Adhesive Compositions (Examples 1 to 14 and Comparative Examples 1 to 5)

The compositions of Examples 1 to 14 and Comparative Examples 1 to 5 were obtained by mixing the polymers 1 to 19 and (B) shown in Table 2 in the ratios shown in Table 3.

3.3. Production of adhesive sheets for evaluation

Each of the compositions of Examples 1 to 14 and Comparative Examples 1 to 5 was applied onto the surface of the release-treated separator film to remove the solvent, and then the separator was bonded to the adhesive surface to obtain an adhesive sheet having an adhesive layer thickness of 50 μm. The separator film on one side of the obtained adhesive sheet was peeled off, and a polyethylene terephthalate film having a thickness of 100 μm was attached to obtain an adhesive sheet for evaluation.

3.4. Test methods

The composition of each of Examples 1 to 14 and Comparative Examples 1 to 5 and the adhesive sheet obtained by using the composition were subjected to an evaluation test by the following method.

3.4.1. Gel rate

1 g of the sample (composition) was placed in 50 ml of ethyl acetate, and it was allowed to stand at room temperature for 24 hours, and then filtered through a 200 mesh stainless steel mesh and dried. Thereafter, a value obtained by dividing the mass of the sample after filtration by the mass of the sample before filtration was calculated as the gel fraction.

3.4.2. Change in haze before and after the damp heat test (whitening resistance)

The separator film on one side of the evaluation adhesive sheet prepared in the above 3.3. was peeled off and peeled off, and the adhesive was laminated on the glass substrate so as to be adhered by using a laminating roll, and a measurement sample was prepared by using a haze meter (type name " HM-150", manufactured by Murakami Color Technology Research Co., Ltd.) The haze (initial haze) was measured. Subsequently, the sample was placed under conditions of 60 ° C to 95% RH for 500 hours, and then moved to 23 ° C to 50% RH, and after 10 minutes, the haze (haze after the wet heat test) was measured. The change in haze before and after the damp heat test (haze after the damp heat test - initial haze) is preferably 3 or less, more preferably 2.5 or less.

3.4.3.180° adhesion

The adhesive sheet for evaluation prepared in the above 3.3. was cut into a size of 25 mm × 150 mm, and the separator film of the obtained adhesive sheet of the example and the like was peeled off at 23 ° C to 50% RH, and the exposed adhesive was exposed. The layer was pressed against the glass plate using a 2 kg roller. After sticking for 20 minutes, the adhesive sheet was peeled off from the glass plate at 23 ° C and a peeling angle of 180 ° at a peeling speed of 300 mm/min, and the adhesive force of the adhesive layer of the adhesive sheet was measured.

3.4.4. Durability (heat resistance, moisture resistance test)

The adhesive sheet for evaluation of the above 3.3. was cut into a size of 50 mm × 60 mm, and the separator film on one side was peeled off, and adhered to one side of the polycarbonate sheet (adhered body) using a laminating roll, followed by The autoclave at 50 ° C and adjusted to 5 atm was kept for 20 minutes to prepare a test plate. The mixture was allowed to stand under the conditions of 85 ° C to 85% RH for 24 hours, and the floatation of the polycarbonate sheet-adhesive layer interface, the generation of foaming, and the like were visually confirmed on the following basis.

(benchmark)

○: No foaming or sticking of the adherend was observed in either of the adhesive layers.

△: Either one of the foaming in the adhesive layer and the floating of the adherend were slightly observed.

×: Any one of the foaming in the adhesive layer and the floating of the adherend were clearly observed.

3.4.5. Specific dielectric ratio

Each of the compositions of Examples 1 to 14 and Comparative Examples 1 to 5 was applied onto the surface of the separator film to remove the solvent, whereby an adhesive layer having a thickness of 100 μm was obtained. Further, another separator film is attached to the adhesive face of the adhesive layer to obtain an adhesive sheet having the adhesive layer. Next, the separator film on one side of the obtained pressure-sensitive adhesive sheet was peeled off and adhered to a copper foil having a thickness of 100 μm, and the separator film on the other surface was further peeled off and adhered to a copper foil having a thickness of 100 μm to obtain a measurement sample. Using a LCR METER 6440B manufactured by TOYO Corporation and bonding it to a copper foil, the specific dielectric constant (100 Hz) was calculated under the conditions of 23 ° C to 65% RH.

In addition, the abbreviation of Table 2 and Table 3 is the following.

AM: acrylamide

nBMA: n-butyl methacrylate

2EHA: 2-ethylhexyl acrylate

2EHMA: 2-ethylhexyl methacrylate

4HBA: 4-hydroxybutyl acrylate

HEMA: 2-hydroxyethyl methacrylate

HPMA: 2-hydroxypropyl methacrylate

LA: Lauryl Acrylate

LMA: lauryl methacrylate

Isodecyl MA: isodecyl methacrylate

CORONATE L: tolyl diisocyanate crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd.)

It is understood that the components of Examples 1 to 14 contain 3% by mass or more and 39% by mass or less of the component (a1) (more specifically, the component (a1) contains 3 mass% or more and 39 mass% or less, and the component (a2) 20 The amount of the adhesive layer obtained by using the composition is lower than the dielectric constant (4.0 or less), and is excellent in adhesion, durability, and moist heat resistance.

On the other hand, in the composition of Comparative Example 1, the monomer mixture for preparing the component (A) does not contain the component (a1), so that the adhesive layer is too hard and the adhesion of the substrate is poor, and adhesion and migration occur. In addition to the poor adhesion, it also produces floating in the heat and humidity test.

It can also be understood that in the composition of Comparative Example 2, the content of the component (a1) in the monomer mixture for preparing the component (A) exceeds 39% by mass, and Since the methacrylate monomer in the monomer mixture is less than 80% by mass, the durability is poor and the specific dielectric constant is high (the specific dielectric constant exceeds 4.0).

Further, the composition of Comparative Example 3 was used to prepare a monomer mixture of the component (A), and the component (a1) was replaced with lauryl acrylate, and the component (A) had a Tg of more than 0 °C. Therefore, the adhesive layer obtained by using the component (A) is hard, so that in addition to adhesion and migration, the adhesion is also poor, and flotation occurs. Further, the adhesive layer obtained by using the component (A) has a higher specific dielectric ratio (specific dielectric ratio exceeding 4.0).

It is also understood that the composition of Comparative Example 4 is used to prepare the monomer mixture of the component (A), and the content of the component (a1) is significantly more than 39% by mass (99% by mass), and the adhesive layer obtained by using the composition is used. Low adhesion and poor durability.

It is also understood that the composition of Comparative Example 5 is used to prepare a monomer mixture of the component (A) in the absence of the component (a2), and the adhesion is poor.

10‧‧‧Liquid Crystal Display Unit (LCD)

11, 15‧‧‧ polarizing plate

12, 14, 17‧‧ ‧ adhesive layer

13‧‧‧LCD panel

16‧‧‧Splash suppression film

18‧‧‧ITO layer

19‧‧‧Glass panel (touch panel)

20‧‧‧Touch Panel Department

30‧‧‧Adhesive layer

100‧‧‧Touch panel type input input device

Claims (19)

An optical adhesive composition comprising a (A) copolymer containing a monomer mixture, wherein the monomer mixture is: (a1) an alkyl methacrylate monomer having a carbon number of 10 or more and 18 or less (%) or more and 39% by mass or less, and (a2) 20% by mass or more and 97% by mass or less of the alkyl methacrylate monomer having an alkyl group having 1 or more and 9 or less carbon atoms, and the component (a1) and the above (a2) The total amount of the components is 45 mass% or more and 100 mass% or less. The optical adhesive composition according to claim 1, wherein the (A) copolymer has a weight average molecular weight of 50,000 or more and 700,000 or less. The optical adhesive composition according to claim 1, wherein the (A) copolymer has a glass transition temperature (Tg) of 0 ° C or less. The optical adhesive composition according to the first aspect of the invention, wherein the content of the component (a2) relative to the content of the component (a1) in the monomer mixture is 0.5 or more and 5 or less. The optical adhesive composition according to claim 1, further comprising (a3) a hydroxyl group-containing monomer in an amount of 2% by mass or more and 30% by mass or less. The optical adhesive composition according to claim 5, wherein the (a3) hydroxyl group-containing monomer is a hydroxyl group-containing methacrylate monomer. The optical adhesive composition according to claim 1, The monomer mixture further contains 0.1% by mass or more and 5% by mass or less of the (a4) nitrogen atom-containing monomer. The optical adhesive composition according to the first aspect of the invention, wherein the total amount of the methacrylate monomers in the monomer mixture is 80% by mass or more and 100% by mass or less. The optical adhesive composition according to the above aspect of the invention, wherein the content of the (A) copolymer in the adhesive composition is 70% by mass or more and 99.9% by mass or less. The optical adhesive composition according to claim 1, wherein the (A) copolymer has a hydroxyl value of 15 or more and 150 or less. The optical adhesive composition according to claim 1, wherein the (A) copolymer has a gel fraction of 30% or more and 90% or less. The optical adhesive composition according to claim 1, wherein the (A) copolymer has a crosslinkable functional group and further contains (B) a crosslinking agent. The optical adhesive composition according to claim 12, wherein the (B) crosslinking agent is contained in an amount of 0.01 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the copolymer (A). The optical adhesive composition according to claim 12, wherein the crosslinking agent (B) is an isocyanate crosslinking agent. The optical adhesive composition according to claim 1, which is used for bonding a member constituting a touch panel type input/output device or an image display device. An adhesive sheet for optics having patent claims 1 to 15 The adhesive layer formed by the optical adhesive composition according to any one of the preceding claims. The optical adhesive sheet according to claim 16, which has a dielectric constant of 4.0 or less at a ratio of 100 Hz. An image display device comprising the optical adhesive sheet according to item 16 of the patent application. An output input device comprising the optical adhesive sheet according to item 16 of the patent application.