TWI824994B - Adhesive compositions, adhesives, adhesive sheets and displays - Google Patents

Abstract

The present invention provides an adhesive composition, an adhesive, an adhesive sheet, and a display that are excellent in both step following properties and foaming resistance. The adhesive composition of the present invention contains: (meth)acrylate polymer (A), as a monomer unit constituting the polymer, including a hydroxyl-containing monomer; a polyrotaxane compound (B), which contains a hydroxyl group as a reactive Based on cyclic oligosaccharide as a cyclic molecule; isocyanate cross-linking agent (C); and reaction accelerator (D) to promote polyurethanization reaction.

Description

Adhesive compositions, adhesives, adhesive sheets and displays

The present invention relates to an adhesive composition, an adhesive, and an adhesive sheet for bonding components of a display, as well as a display obtained by using an adhesive layer of the adhesive sheet.

In recent years, various mobile electronic devices such as smartphones and tablet terminals have been equipped with a display using a display module, which is usually a touch panel. The display module has a liquid crystal element, a light-emitting diode (LED element), and a Electromechanical luminescence (organic EL) elements, etc.

In the above-mentioned display, a protective panel is usually provided on the surface side of the display module. As electronic devices become thinner and lighter, the above-mentioned protective panels are changed from conventional glass plates to plastic plates such as acrylic plates and polycarbonate plates.

Here, a gap is provided between the protective panel and the display module to prevent the deformed protective panel from colliding with the display module when the protective panel is deformed due to external force.

However, if there is a gap as mentioned above, that is, an air layer, the light reflection loss caused by the difference in refractive index between the protective panel and the air layer, and the difference in refractive index between the air layer and the display module will increase, and there will be The problem of display quality degradation.

Therefore, it is proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, the frame-shaped printed layer may exist as a step on the display module side of the protective panel. If the adhesive layer does not follow the step, the adhesive layer floats near the step, causing light reflection loss. Therefore, the above-mentioned adhesive layer is required to have step followability.

In order to solve the above problems, Patent Document 1 discloses an adhesive with a shear storage modulus (G') at 25°C and 1 Hz of 1.0×10 ⁵ Pa or less and a gel fraction of 40% or more. layer, as an adhesive layer that fills the gap between the protective panel and the display module.

[Previous technical literature] 【Patent Document】

Patent Document 1: Japanese Patent Application Publication No. 2010-097070

In Patent Document 1, an attempt is made to improve step followability by reducing the storage elastic modulus of the adhesive layer at room temperature. However, if the storage elastic modulus at room temperature is reduced as described above, the storage elastic modulus at high temperature will be too low, causing problems under durability conditions. For example, when high-temperature and high-humidity conditions are applied, bubbles are generated near the step, or air leakage occurs from the plastic sheet used as a protective panel, causing bubbles, floating, and peeling. On the other hand, if the adhesive layer is made hard in order to improve the foaming resistance, the step followability will decrease.

The present invention was completed in view of the above-mentioned actual situation, and its purpose is to provide an adhesive composition that is excellent in both step following properties and blistering resistance. Products, adhesives, adhesive sheets and displays.

In order to achieve the above object, first, the present invention provides an adhesive composition, which is characterized by containing: (meth)acrylate polymer (A), as a monomer unit constituting the polymer, including a hydroxyl-containing monomer; Rotaxane compound (B) has a cyclic oligosaccharide containing a hydroxyl group as a reactive group as a cyclic molecule; an isocyanate-based cross-linking agent (C); and a reaction accelerator (D) to promote polyurethanization reaction (Invention 1) .

It is deduced that if the adhesive composition of the above invention (Invention 1) is cross-linked, the hydroxyl group derived from the hydroxyl-containing monomer of the (meth)acrylate polymer (A) and the cyclic low-density hydroxyl group of the polyrotaxane compound (B) will The hydroxyl group of the polysaccharide reacts well with the isocyanate group of the isocyanate cross-linking agent (C), and a plurality of (meth)acrylate polymers (A) can be mechanically bonded to each other through the polyrotaxane compound (B). It is formed by high-order structures such as three-dimensional network structures. Furthermore, the above-mentioned high-order structure is formed reliably and at high density by the polyurethanization reaction accelerating effect of the reaction accelerator (D). Due to this high-order structure, the resulting adhesive exhibits high stress relaxation properties and excellent step followability, and also has high cohesion and excellent foaming resistance.

In the above invention (Invention 1), the content of the polyrotaxane compound (B) in the adhesive composition is 0.5 parts by mass or more and 20 parts by mass based on 100 parts by mass of the (meth)acrylate polymer (A). Parts by mass or less are preferred (Invention 2).

In the above inventions (Inventions 1 and 2), the content of the reaction accelerator (D) in the adhesive composition is 0.01 parts by mass or more based on 100 parts by mass of the (meth)acrylate polymer (A). 1.5 parts by mass or less is better (Invention 3).

In the above inventions (Inventions 1 to 3), the (meth)acrylate polymer (A) contains 3% by mass or more and 30% by mass or less of the hydroxyl-containing monomer as a monomer unit constituting the polymer. is better (Invention 4).

Second, the present invention provides an adhesive which is cross-linked with the aforementioned adhesive composition (Inventions 1 to 4) (Invention 5).

In the above invention (Invention 5), the gel fraction is preferably 30% or more and 90% or less (Invention 6).

Third, the present invention provides an adhesive sheet, which has an adhesive layer. The adhesive layer is used to bond one display component and another display component with a step difference at least on the side to be bonded. The characteristics of the invention are: In this case, the adhesive layer is composed of the adhesive (Inventions 5 and 6) (Invention 7).

In the above invention (Invention 7), it is preferable that the step following rate of the adhesive layer is 20% or more (Invention 8).

In the above-mentioned inventions (Inventions 7 and 8), it is preferable that the adhesive sheet includes two release sheets, and the adhesive layer is sandwiched by the release sheets so as to be in contact with the release surfaces of the two release sheets (Invention 9).

Fourth, the present invention provides a display body, which is provided with: one display body constituent member, which has a step at least on the surface of the side to be bonded; another display body constituent member; and an adhesive layer, which is mutually bonded to the aforementioned one display body constituent member. Constituting a component with the aforementioned another display body, the aforementioned display body is characterized in that the aforementioned adhesive layer is the adhesive layer (Invention 10) of the aforementioned adhesive sheet (Inventions 7 to 9).

Adhesive composition, adhesive, adhesive sheet and display of the present invention It is excellent in both body step followability and blistering resistance.

1‧‧‧Adhesive sheet

11‧‧‧Adhesive layer

12a, 12b‧‧‧Peel-off sheet

2‧‧‧Display body

21‧‧‧Components of the first display body

22‧‧‧Second display body components

3‧‧‧Printing layer

Figure 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

Figure 2 is a cross-sectional view of a laminated body according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

[Adhesive composition]

The adhesive composition (hereinafter, sometimes referred to as "adhesive composition P") of this embodiment contains (meth)acrylate polymer (A), which contains a hydroxyl-containing monomer unit as a monomer unit constituting the polymer. Monomer; polyrotaxane compound (B), which has a cyclic oligosaccharide containing a hydroxyl group as a reactive group as a cyclic molecule; isocyanate cross-linking agent (C); and reaction accelerator (D), which promotes polyurethanization reaction . In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, "polymer" also includes the concept of "copolymer".

When the adhesive composition P of this embodiment is cross-linked, the isocyanate group of the isocyanate-based cross-linking agent (C) reacts with the hydroxyl group derived from the hydroxyl-containing monomer of the (meth)acrylate polymer (A), and The isocyanate group of the isocyanate cross-linking agent (C) reacts with the hydroxyl group of the cyclic molecule of the polyrotaxane compound (B). It is inferred from this that the (meth)acrylate polymer (A) is bonded to one cyclic molecule of the polyrotaxane compound (B) through the hydroxyl group and the isocyanate cross-linking agent (C). Similarly, the other (methyl ) The acrylate polymer (A) is bonded to other cyclic molecules of the polyrotaxane compound (B). Here, polyrotaxane Compound (B) has a mechanical bond between a cyclic molecule and a linear molecule extending through the cyclic molecule, and the cyclic molecule can move freely on the linear molecule. As a result, it is inferred that a plurality of (meth)acrylate polymers (A) are formed by a higher-order structure such as a three-dimensional network structure in which polyrotaxane compounds (B) are mechanically bonded to each other. Due to this high-order structure, the obtained adhesive exhibits high stress relaxation properties and has excellent step followability. For example, when an adhesive sheet obtained using the adhesive composition P of this embodiment is attached to a display component having a step, the adhesive layer easily follows the step, thereby suppressing the occurrence of gaps, floating, etc. near the step. Furthermore, even when left in this state under high temperature and high humidity conditions, such as 85°C and 85% RH for 72 hours, the occurrence of bubbles, floating, peeling, etc. near the step can be suppressed.

Furthermore, when the adhesive composition P of this embodiment is cross-linked, the hydroxyl-containing monomer derived from the (meth)acrylate polymer (A) is The hydroxyl group of the cyclic oligosaccharide of the polyrotaxane compound (B) reacts favorably with the isocyanate group of the isocyanate cross-linking agent (C) to form the above-mentioned higher-order structure reliably and at high density. Thereby, the obtained adhesive maintains excellent stress relaxation properties, has high cohesive force, and has excellent foaming resistance. For example, when a display obtained using the adhesive composition P of this embodiment is placed under high temperature and high humidity conditions (for example, 85°C, 85% RH), air leakage occurs from the display component composed of a plastic plate or the like. , and can also suppress bubbling such as bubbles, floating, and peeling at the interface between the adhesive layer and the display component.

In addition, it is not necessary that all the adhesives obtained have the above deduced structure, and may also contain two (meth)acrylate polymers (A) without passing through the polyurethane. Alkane compound (B), but a structure directly bonded through an isocyanate cross-linking agent (C).

(1) (Meth)acrylate polymer (A)

The (meth)acrylate polymer (A) of this embodiment contains a hydroxyl-containing monomer as a monomer unit constituting the polymer.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. Hydroxyalkyl (meth)acrylate, such as hydroxybutyl ester, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, from the viewpoint of the reactivity of the hydroxyl group in the obtained (meth)acrylate polymer (A) with the isocyanate cross-linking agent (C) and the copolymerizability with other monomers, (meth)acrylic acid 2 -Hydroxyethyl ester or 4-hydroxybutyl (meth)acrylate is preferred. These may be used individually or in combination of two or more.

The (meth)acrylate polymer (A) preferably contains 3% by mass or more of a hydroxyl-containing monomer as a monomer unit constituting the polymer, more preferably 5% by mass or more, and more preferably 10% by mass or more. good. If the content of the hydroxyl-containing monomer is 3% by mass or more, the cohesive force of the resulting adhesive is improved, thereby improving the foaming resistance and step followability under high temperature and high humidity conditions. Furthermore, the (meth)acrylate polymer (A) preferably contains 30 mass % or less of a hydroxyl-containing monomer as a monomer unit constituting the polymer, particularly preferably 25 mass % or less, and 20 mass % or less. % or less is more preferred. If the content of the hydroxyl-containing monomer is 30% by mass or less, appropriate adhesiveness is easily obtained, the adhesive is suppressed from becoming too hard, and step followability becomes more excellent.

In the (meth)acrylate polymer (A), as the monomer unit constituting the polymer, an alkyl (meth)acrylate with a carbon number of 1 to 20 containing an alkyl group can exhibit better adhesion. sex. From this point of view, the (meth)acrylate polymer (A) contains (meth)acrylic acid having an alkyl group having 1 to 20 carbon atoms in an amount of 50% by mass or more as a monomer unit constituting the polymer. Alkyl ester is preferred, and its content of 60 mass% or more is particularly preferred, and its content of 70 mass% or more is even more preferred. If it contains 50 mass % or more of the said alkyl (meth)acrylate, the (meth)acrylate polymer (A) can exhibit appropriate adhesiveness. Furthermore, in the (meth)acrylate polymer (A), as a monomer unit constituting the polymer, an alkyl (meth)acrylate having a carbon number of 1 to 20 containing 97% by mass or less of an alkyl group is More preferably, the content is 90% by mass or less, and the content is more preferably 85% by mass or less. By setting the alkyl (meth)acrylate content to 97% by mass or less, an appropriate amount of other monomer components can be introduced into the (meth)acrylate polymer (A).

Examples of alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylate. n-butyl acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylic acid n-decyl ester, n-dodecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-cetyl (meth)acrylate, n-octadecyl (meth)acrylate ester, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, etc. Among them, from the perspective of further improving the adhesion, the number of carbon atoms containing the alkyl group is 1 (Meth)acrylate of ~8 is preferred. These can be used individually or Use in combination of two or more.

In addition, as the alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms, a monomer (hard monomer) having a glass transition temperature (Tg) exceeding 0°C as a homopolymer and a homopolymer are used in combination. Monomers (soft monomers) with a glass transition temperature (Tg) of 0°C or lower are preferred. This is because the soft monomer ensures adhesion and flexibility, and the hard monomer improves the cohesion, making it possible to achieve better foaming resistance and step followability. At this time, the mass ratio of hard monomers to soft monomers is preferably 5:95~40:60, and 20:80~30:70 is particularly suitable.

Examples of the hard monomer include methyl acrylate (Tg10°C), methyl methacrylate (Tg105°C), isobornyl acrylate (Tg94°C), isobornyl methacrylate (Tg180°C), and diamond acrylate. Alkyl ester (Tg115℃), adamantyl methacrylate (Tg141℃), etc. These may be used individually or in combination of two or more.

Among the above-mentioned hard monomers, methyl acrylate, methyl methacrylate, and isobornyl acrylate (acrylic acid isobornyl) is preferred. If adhesion is also considered, methyl acrylate and methyl methacrylate are more preferred.

Preferred examples of the soft monomer include alkyl acrylates having a linear or branched alkyl group having 2 to 12 carbon atoms. For example, 2-ethylhexyl acrylate (Tg-70°C), n-butyl acrylate (Tg-54°C), etc. are preferred. These may be used individually or in combination of two or more.

Furthermore, as the alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms, at least a part of the alkyl (meth)acrylate has Alicyclic structures are also preferred as monomers of alkyl groups (monomers containing alicyclic structures). Since the monomer containing an alicyclic structure is relatively large in volume, it is presumed that by its presence in the polymer, the distance between the polymers can be widened, and the resulting adhesive can be excellent in flexibility. As a result, the adhesive has better step followability.

The carbocyclic ring of the alicyclic structure in the monomer containing an alicyclic structure may be a saturated structure, or may be partially unsaturated bonded. Moreover, the alicyclic structure may be a single-ring alicyclic structure, or may be a bicyclic, tricyclic, or other polycyclic alicyclic structure. From the viewpoint of appropriate distance between the obtained (meth)acrylate polymers (A) and imparting higher stress relaxation properties to the adhesive, the alicyclic structure is a polycyclic alicyclic structure. (polycyclic structure) is preferred. In addition, in consideration of the compatibility between the (meth)acrylate polymer (A) and other components, it is particularly preferred that the polycyclic structure be bicyclic to tetracyclic. Furthermore, from the viewpoint of imparting stress relaxation properties as described above, the number of carbon atoms in the alicyclic structure (refers to the number of all carbon atoms forming the part of the ring), and when a plurality of rings exist independently, refers to the total number of carbon atoms. ) is usually 5 or more, especially 7 or more. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited. From the viewpoint of compatibility as described above, 15 or less is preferred, and 10 or less is particularly preferred.

Specific examples of the alicyclic structure-containing monomer include (meth)acrylic acid cyclohexyl, (meth)acrylic acid dicyclopentyl, (meth)acrylic acid adamantyl ester, (meth)acrylic acid Isobornyl ester, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc. Among them, (meth)acrylic acid exhibits better step followability under hot and humid conditions. Dicyclopentyl ester (number of carbon atoms in the alicyclic structure: 10), adamantyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 10) or isobornyl (meth)acrylate (number of carbon atoms in the alicyclic structure: 10) The number of carbon atoms in the structure: 7) is preferred, and isobornyl (meth)acrylate is particularly preferred. These may be used individually by 1 type, and may be used in combination of 2 or more types.

When the (meth)acrylate polymer (A) contains an alicyclic structure-containing monomer as a constituent monomer unit, the alicyclic structure of an alkyl (meth)acrylate having a carbon number of 1 to 20 in the alkyl group The proportion of structural monomers is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more. Furthermore, the proportion of the alicyclic structure-containing monomer is preferably 50 mass% or less, particularly preferably 40 mass% or less, and further preferably 30 mass% or less. If the content of the alicyclic structural monomer is within the above range, the resulting adhesive will have better step followability and can fully exhibit its excellent adhesion to transparent conductive films and plastics.

Furthermore, the (meth)acrylate polymer (A) preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By making a nitrogen atom-containing monomer exist as a structural unit in a polymer, a predetermined polarity is given to the adhesive, and it can have excellent affinity for an adherend having polarity as high as glass. Examples of the nitrogen atom-containing monomer include a monomer having an amino group, a monomer having a amide group, a monomer having a nitrogen-containing heterocyclic ring, and the like. Among them, a monomer having a nitrogen-containing heterocyclic ring is preferred.

Examples of the monomer having a nitrogen-containing heterocycle include N-(meth)acrylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acrylpyrrolidone, N-(meth)acrylylmorpholine, N-(meth)acrylylpiperidine, N-(meth)acrylylpyrrolidine, N-(meth)acrylaziridine, (meth)aziridinylethyl acrylate, 2-vinylpyridine , 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthaloimide, etc., among which, N-(meth)acrylyl morpholine, which exhibits more excellent adhesion, is preferred, and N-acrylyl morpholine is particularly preferred.

In addition, as the nitrogen atom-containing monomer, for example, (meth)acrylamide, N-methyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-tert-butylamine can also be used. (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-ethyl(meth)acrylamide, N,N-dimethylaminopropyl( Meth)acrylamide, N-isopropyl(meth)acrylamide, N-phenyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, N-ethylene Caprolactam, monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, (meth)acrylic acid Monoethylaminopropyl ester, dimethylaminoethyl (meth)acrylate, etc. The above nitrogen atom-containing monomers may be used alone or in combination of two or more.

The (meth)acrylate polymer (A) preferably contains 0.5% by mass or more of nitrogen atom-containing monomers as monomer units constituting the polymer, more preferably 1% by mass or more, and further preferably 3% by mass or more. Better. Furthermore, the (meth)acrylate polymer (A) preferably contains 20 mass % or less of nitrogen atom-containing monomers as monomer units constituting the polymer, particularly preferably 15 mass % or less, and 8 mass % or less. The following are further preferred. If the content of the nitrogen atom-containing monomer is within the above range, the resulting adhesive can fully exhibit excellent adhesion to glass.

The (meth)acrylate polymer (A) may contain other monomers as monomer units constituting the polymer if necessary. As other monomers, they may be monomers containing reactive functional groups (other than hydroxyl groups), or they may not contain Monomers containing reactive functional groups.

Preferable examples of the monomer containing a reactive functional group include carboxyl group-containing monomers. Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among them, acrylic acid is preferable from the viewpoint of its influence on the reaction between the hydroxyl group derived from the hydroxyl group-containing monomer and the isocyanate cross-linking agent (C) and the copolymerizability with other monomers. These can be used individually or in combination of 2 or more types.

When the (meth)acrylate polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the content is preferably 0.5% by mass or more, and particularly preferably 1% by mass or more. Furthermore, the content is preferably 20 mass% or less, and particularly preferably 10 mass% or less.

In addition, from the viewpoint of easily controlling the cross-linked structure of the obtained adhesive, it is also preferable to use only a monomer containing a reactive functional group as the aforementioned hydroxyl-containing monomer.

On the other hand, examples of the monomer that does not contain a reactive functional group include (meth)acrylic acid alkoxyethyl (meth)acrylic acid methoxyethyl, (meth)acrylic acid ethoxyethyl, etc. alkyl esters, vinyl acetate, styrene, etc. These can be used individually or in combination of 2 or more types.

The polymerization form of the (meth)acrylate polymer (A) may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and further preferably 400,000 or more. If the lower limit value of the weight average molecular weight of the (meth)acrylate polymer (A) is more than the above, the obtained adhesive will have excellent foaming resistance.

Furthermore, the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 1 million or less, particularly preferably 800,000 or less, and further preferably 700,000 or less. If the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is the above or lower, the obtained adhesive will have further excellent step followability. In addition, the weight average molecular weight in this specification is a standard polystyrene-converted value measured by gel permeation chromatography (GPC) method.

In addition, in the adhesive composition P, one type of (meth)acrylate polymer (A) may be used alone, or two or more types may be used in combination.

(2)Polyrotaxane compound (B)

The polyrotaxane compound (B) is a compound in which a linear molecule penetrates the openings of at least two cyclic molecules and has protective groups at both ends of the linear molecule. The polyrotaxane compound (B) has a structure in which the cyclic molecule can move freely on the linear molecule, and the cyclic molecule cannot be separated from the linear molecule due to the protective group. That is, linear molecules and cyclic molecules are not chemical bonds such as covalent bonds, but maintain their shape through so-called mechanical bonds. The adhesive composition P of this embodiment contains the polyrotaxane compound (B) having the mechanical bond, if (meth)acrylate polymer (A) and the polyrotaxane compound (B) (cyclic molecule) When the polyrotaxane compound (B) is cross-linked via the isocyanate-based cross-linking agent (C), the cyclic molecules can move freely on the linear molecules, thereby significantly improving the flexibility of the cross-linked body. Thereby, the obtained adhesive exhibits very high stress relaxation properties and has excellent step followability.

The polyrotaxane compound (B) of this embodiment has a cyclic oligosaccharide as a cyclic molecule. By using a cyclic oligosaccharide as a cyclic molecule of the polyrotaxane compound (B), an appropriate ring diameter can be selected, thereby making it easy to form a cyclic shape. The effect brought about by the movement of molecules on linear molecules. Furthermore, since the cyclic oligosaccharide has a hydroxyl group as a reactive group, it easily reacts with the isocyanate cross-linking agent (C). Furthermore, it is easy to introduce various substituents and the like, whereby the compatibility between the polyrotaxane compound (B) and other components can be adjusted by the polyrotaxane compound (B). Furthermore, if it is a cyclic oligosaccharide, it has the advantage of being easily available. In addition, in this specification, the "cyclic" of "cyclic molecule" or "cyclic oligosaccharide" means substantially "cyclic". That is, as long as it can move on a linear molecule, the cyclic molecule does not need to be completely closed, and may have a helical structure, for example.

Preferable examples of the cyclic oligosaccharide include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and among these, α-cyclodextrin is particularly preferred. Two or more types of cyclic molecules of the polyrotaxane compound (B) may be mixed in the polyrotaxane compound (B) or in the adhesive composition P.

The cyclic molecule (cyclic oligosaccharide) of the polyrotaxane compound (B) has a hydroxyl group as a reactive group. The hydroxyl group may be a hydroxyl group that the cyclic oligosaccharide has in its original state (meaning the state before modification), or it may be a hydroxyl group introduced into the cyclic oligosaccharide as a substituent.

Regarding the hydroxyl value of the above-mentioned cyclic molecule, the lower limit value is preferably 10 mgKOH/g or more, more preferably 30 mgKOH/g or more, and particularly preferably 50 mgKOH/g or more. If the lower limit of the hydroxyl value is equal to or higher than the above, the polyrotaxane compound (B) and the isocyanate-based crosslinking agent (C) can fully react. Furthermore, the upper limit of the hydroxyl value of the cyclic molecule is preferably 1,000 mgKOH/g or less, more preferably 200 mgKOH/g or less, and particularly preferably 100 mgKOH/g or less. If the upper limit of the hydroxyl value exceeds the above value, multiple crosslinks occur in the same cyclic molecule, and the cyclic molecule itself becomes a crosslinking point and cannot function as a crosslinking point for the entire polyrotaxane compound (B). As a result, sufficient stress relaxation properties of the adhesive layer may not be ensured.

The linear molecule of the polyrotaxane compound (B) is a molecule or substance that is included in a cyclic molecule and can be integrated through mechanical bonding that is not a chemical bond such as covalent bonding. As long as it is linear, then There are no special restrictions. In addition, in this specification, "linear" in "linear molecule" means substantially "linear". That is, as long as the cyclic molecule can move on the linear molecule, the linear molecule may have branches.

Examples of linear molecules of the polyrotaxane compound (B) include polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polyacrylate, and polydimethylsiloxy. Alkanes, polyethylene, polypropylene, etc. are preferred, and two or more of these linear molecules may be mixed in the adhesive composition P.

Regarding the number average molecular weight of the linear molecules of the polyrotaxane compound (B), the lower limit is preferably 3,000 or more, particularly 10,000 or more, and further preferably 20,000 or more. If the lower limit of the number average molecular weight is equal to or higher than the above, the amount of movement of cyclic molecules on linear molecules can be ensured, and the stress relaxation properties of the adhesive can be fully obtained. Furthermore, regarding the number average molecular weight of the linear molecules of the polyrotaxane compound (B), the upper limit is preferably 300,000 or less, particularly preferably 200,000 or less, and further preferably 100,000 or less. When the upper limit of the number average molecular weight is the above or lower, the solubility of the polyrotaxane compound (B) in the solvent or the compatibility with the (meth)acrylate polymer (A) becomes good.

The protecting group of the polyrotaxane compound (B) is not particularly limited as long as it is a group that can maintain the cyclic molecule in a string-like form via linear molecules. Examples of such groups include bulky groups, ionic groups, and the like.

Specifically, the protecting group of the polyrotaxane compound (B) is dinitrophenyl, cyclodextrin, adamantyl ester, trityl, fluorescein, pyrene, anthracene, etc. or The main chain or side chain of a polymer with a number average molecular weight of 1,000 to 1,000,000 is preferred. Two or more of these protective groups may be mixed in the polyrotaxane compound (B) or the adhesive composition P.

The polyrotaxane compound (B) described above can be obtained by a conventionally known method (for example, the method described in Japanese Patent Application Laid-Open No. 2005-154675).

Regarding the content of the polyrotaxane compound (B) in the adhesive composition P of this embodiment, the lower limit is preferably 0.5 parts by mass or more based on 100 parts by mass of the (meth)acrylate polymer (A). , 1 part by mass or more is particularly preferred, and 3 parts by mass or more is even more preferred. If the content of the polyrotaxane compound (B) is equal to or higher than the above lower limit, the stress relaxation properties and step followability due to the polyrotaxane compound (B) will be more excellent. Moreover, regarding the content of the polyrotaxane compound (B), the upper limit is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. If the content of the polyrotaxane compound (B) is below the above upper limit, the compatibility with the (meth)acrylate polymer (A) can be maintained well, and the haze value of the obtained adhesive can be reduced. Inhibition is low.

(3) Isocyanate cross-linking agent (C)

The isocyanate cross-linking agent (C) and the (meth)acrylate polymer (A) originate from the hydroxyl group of the hydroxyl-containing monomer and the cyclic molecules (i.e., cyclic oligomerization) possessed by the polyrotaxane compound (B). Sugar) has excellent reactivity between hydroxyl groups.

The isocyanate cross-linking agent (C) contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate. Aliphatic polyisocyanates such as isocyanate and hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and their biuret bodies and isocyanurate bodies , and ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. as adducts with reactants containing low molecular active hydrogen compounds. Among them, from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanate is preferred, and trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferred. Diisocyanates are particularly preferred. In addition, one type of isocyanate cross-linking agent (C) may be used alone, or two or more types may be used in combination.

Regarding the content of the isocyanate cross-linking agent (C) in the adhesive composition P, the lower limit is preferably 0.05 parts by mass or more based on 100 parts by mass of the (meth)acrylate polymer (A), and 0.1 parts by mass Particularly preferably at least 0.2 parts by mass, more preferably at least 0.2 parts by mass. If the lower limit of the content of the isocyanate cross-linking agent (C) is more than the above, it is inferred that the above-mentioned higher-order structure can be formed favorably, and the resulting adhesive will have better foaming resistance and step-following properties under high temperature and high humidity. . Furthermore, regarding the content of the isocyanate cross-linking agent (C), the upper limit is preferably 3 parts by mass or less, and particularly preferably 2 parts by mass or less, based on 100 parts by mass of the (meth)acrylate polymer (A). More preferably, it is 1 part by mass or less. If the upper limit of the content of the isocyanate cross-linking agent (C) is equal to or less than the above, the degree of cross-linking can be set to an appropriate level, and the step-following properties of the obtained adhesive can be well ensured.

(4)Reaction accelerator (D)

The reaction accelerator (D) of this embodiment is a reaction accelerator that accelerates the polyurethanization reaction. That is, the reaction accelerator (D) promotes (meth)acrylate poly The reaction between the hydroxyl group derived from the hydroxyl-containing monomer of the compound (A) and the hydroxyl group of the cyclic oligosaccharide of the polyrotaxane compound (B) and the isocyanate group of the isocyanate-based cross-linking agent (C) can reliably Form the aforementioned higher-order structure. As a result, the adhesive obtained has particularly excellent foaming resistance.

Examples of the reaction accelerator (D) include compounds of heavy metals such as tin, lead, mercury, and bismuth (including organic metal compounds); and complexes of transition metals such as titanium, iron, copper, zirconium, nickel, cobalt, and manganese. , especially acetyl acetone complex; amine compounds; acid catalysts such as p-toluenesulfonic acid, phosphoric acid, hydrochloric acid, ammonium chloride, etc. Among these, organic tin compounds and amine compounds are preferable from the viewpoint of accelerating the polyurethanization reaction, and organic tin compounds are particularly preferable. Moreover, the crosslinking accelerator (C) may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of the organotin compound include organotin compounds such as dimethyltin dichloride; dimethyltin dilaurate, dimethyltin di(2-ethylhexanoic acid), and dimethyltin diacetic acid. ester, dibutyltin dilaurate, dihexyltin diacetate, dioctyltin dilaurate and other organotin compound fatty acid salts; dimethyltin bis(isooctyl thioglycolate) salt, dimethyltin bis(isooctyl thioglycolate) salt, Thioglycolic acid ester salts of organotin compounds such as octyltin bis(isooctyl thioglycolic acid acetate) salt; metal soaps such as tin octoate and tin decanoate, etc. Among the above, fatty acid salts of organotin compounds are preferred from the viewpoint of accelerating the polyurethanation reaction, and dibutyltin dilaurate is particularly preferred.

Examples of the amine compound include N,N,N',N'-tetramethylhexanediamine, triethylamine, imidazole, and the like. Among the above, triethylamine is preferred from the viewpoint of accelerating the polyurethanation reaction.

Regarding the content of the reaction accelerator (D) in the adhesive composition P The lower limit is preferably 0.001 parts by mass or more, particularly preferably 0.003 parts by mass or more, and further preferably 0.005 parts by mass or more, based on 100 parts by mass of the (meth)acrylate polymer (A). If the content of the reaction accelerator (D) is more than the above lower limit, the above-mentioned higher-order structure can be favorably formed, and the resulting adhesive will have better foaming resistance. Furthermore, regarding the content, the upper limit is preferably 1.0 parts by mass or less, particularly preferably 0.5 parts by mass or less, and further preferably 0.3 parts by mass or less. If the content of the reaction accelerator (D) is below the above upper limit, the adhesiveness of the obtained adhesive can be maintained well.

(5)Reaction inhibitor

It is also preferable that the adhesive composition P contains a reaction inhibitor in addition to the above-mentioned components. In the adhesive composition P, depending on the type and content of the reaction accelerator (D), the polyurethanization reaction (cross-linking reaction) of the components (A) to (C) may start during the storage stage (the stage before heating). By containing a reaction inhibitor, the storage stability (pot life) of the adhesive composition P at room temperature can be improved.

Examples of reaction inhibitors include acetylenic compounds, oxime compounds, organic nitrogen compounds, organic phosphorus compounds, and organic chlorine compounds. Among these, an acetylenic compound is preferable from the viewpoint of the reaction inhibitory effect of the polyurethanation reaction, and acetylacetone is particularly preferable. The above reaction inhibitors usually evaporate during the drying process when forming the adhesive layer. In addition, one type of reaction inhibitor may be used alone, or two or more types may be used in combination.

The content of the reaction inhibitor in the adhesive composition P is preferably 0.1 parts by mass or more, particularly preferably 0.2 parts by mass or more, and 0.5 parts by mass relative to 100 parts by mass of the (meth)acrylate polymer (A). The above is further preferred. Furthermore, the content is preferably 10 parts by mass or less, particularly 5 parts by mass or less. Preferably, it is more preferably 3 parts by mass or less. When the content of the reaction inhibitor is within the above range, the storage stability of the adhesive composition P can be effectively improved.

(6) Various additives

In the adhesive composition P, various additives commonly used in acrylic adhesives can be added as needed, such as silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, and fillers. agents, refractive index adjusters, etc. In addition, the polymerization solvent and the dilution solvent mentioned later are not included in the additives constituting the adhesive composition P.

Here, if the adhesive composition P contains a silane coupling agent, the adhesiveness between the obtained adhesive and the glass member or plastic plate will be improved. As a result, the adhesive obtained has better foaming resistance.

The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the (meth)acrylate polymer (A), and having light transmittance.

Examples of such silane coupling agents include silicon compounds containing polymerizable unsaturated groups such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane. 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and other silicon compounds with epoxy structure, 3-mercaptopropyltrimethoxy Silane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane and other thiol-containing silicon compounds, 3-aminopropyltrimethoxysilane, N-(2-amino Ethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and other amine-containing silicon compounds, 3-chloro Propyltrimethoxysilane, 3-isocyanate propyltriethoxysilane, or at least one of these and methyl Condensates of alkyl-containing silicon compounds such as triethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. One type of these may be used alone, or two or more types may be used in combination.

When the adhesive composition P contains a silane coupling agent, the content is preferably 0.01 part by mass or more, particularly preferably 0.05 part by mass or more, and 0.1 part by mass or more based on 100 parts by mass of the (meth)acrylate polymer (A). Better still. Furthermore, the content is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less.

(7) Manufacturing of adhesive compositions

The adhesive composition P can be produced by producing a (meth)acrylate polymer (A) and mixing the obtained (meth)acrylate polymer (A) and the polyrotaxane compound (B). ), isocyanate cross-linking agent (C) and reaction accelerator (D), and add additives as needed.

The (meth)acrylate polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a common radical polymerization method. The (meth)acrylate polymer (A) is preferably polymerized by a solution polymerization method using a polymerization initiator if necessary. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more types may be used in combination.

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more types may be used in combination. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis(cyclohexane). Alkane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentane) Nitrile), dimethyl 2,2'-azobis (2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'- Azobis[2-(2-imidazolin-2-yl)propane], etc.

Examples of organic peroxides include benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and diisopropyl peroxydicarbonate. (2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexanoic acid) peroxide, Dipropyl peroxide, diethyl peroxide, etc.

In addition, in the above-mentioned polymerization process, by blending a chain transfer agent such as 2-mercaptoethanol, the weight average molecular weight of the obtained polymer can be adjusted.

If the (meth)acrylate polymer (A) is obtained, the polyrotaxane compound (B), the isocyanate cross-linking agent (C), and the reaction accelerator are added to the solution of the (meth)acrylate polymer (A). (D), and add a diluting solvent and additives as necessary, and mix thoroughly to obtain an adhesive composition P (coating solution) diluted with a solvent. In addition, when any of the above-mentioned components is used in a solid state or when precipitation occurs when mixed with other components in an undiluted state, the component may be separately dissolved in advance or diluted in a diluting solvent and then mixed with other components.

Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and dichloroethane, methanol, ethanol, and propanol. Butanol, 1-methoxy-2-propanol and other alcohols, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, butyl acetate and other esters, ethyl cellosolve Cellosolve solvents, etc.

The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within the range that can be coated, and can be appropriately selected according to the situation. Certainly. For example, the concentration of the adhesive composition P is diluted to 10 to 60% by mass. In addition, when the coating solution is obtained, the addition of a diluting solvent is not a necessary condition. As long as the adhesive composition P has a viscosity that can be coated, the diluting solvent does not need to be added. At this time, the adhesive composition P becomes a coating solution in which the polymerization solvent of the (meth)acrylate polymer (A) is directly used as the diluting solvent.

〔Adhesive〕

The adhesive agent of this embodiment is cross-linked adhesive composition P. Crosslinking of the adhesive composition P can usually be performed by heat treatment. In addition, the heating process can also be combined with a drying process when evaporating a diluting solvent or the like from the coating film of the adhesive composition P applied to a desired object.

The heating temperature for the heat treatment is preferably 50 to 150°C, and particularly preferably 70 to 120°C. Moreover, the heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period (curing period) of about 1 to 2 weeks can be set at normal temperature (for example, 23°C, 50%RH) as needed. When the aging period is required, the adhesive is formed after the aging period. When the aging period is not required, the adhesive is formed after the heat treatment is completed.

By the above-mentioned heat treatment (and aging), the (meth)acrylate polymer (A) and the polyrotaxane compound (B) are fully cross-linked via the isocyanate-based cross-linking agent (C). The adhesive obtained in this way is excellent in both step following properties and foaming resistance.

Regarding the gel fraction of the adhesive in this embodiment, the lower limit is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more. If the lower limit value of the gel fraction of the adhesive is more than the above, the cohesive force of the adhesive becomes high, Better foaming resistance. Furthermore, regarding the gel fraction of the adhesive in this embodiment, the upper limit is preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less. If the upper limit of the gel fraction of the adhesive is equal to or less than the above, the adhesive will not become too hard and the step followability will be more excellent. Here, the method for measuring the gel fraction of the adhesive is as shown in the test examples described below.

[Adhesive sheet]

The adhesive sheet of this embodiment has an adhesive layer for bonding one display component and another display component having a step at least on the surface of the bonded side, and the adhesive layer is composed of the aforementioned Adhesive builder.

The specific structure of an example of the adhesive sheet of this embodiment is shown in FIG. 1 .

As shown in FIG. 1 , the adhesive sheet 1 according to one embodiment is composed of two release sheets 12 a and 12 b; The adhesive layer 11 sandwiched by 12a and 12b. In addition, the release surface of the release sheet in this specification refers to the surface of the release sheet that has releasability, and includes both the surface that has been subjected to release treatment and the surface that shows releasability even if no release treatment has been performed.

(1)Adhesive layer

The adhesive layer 11 is composed of the above-mentioned adhesive, that is, an adhesive formed by cross-linking the adhesive composition P.

Regarding the thickness of the adhesive layer 11 of the adhesive sheet 1 of this embodiment (value measured in accordance with JIS K7130), the lower limit is preferably 10 μm or more, more preferably 25 μm or more, and particularly preferably 50 μm or more. If the lower limit of the thickness of the adhesive layer 11 is more than the above, the desired adhesive force can be easily exerted and the thickness can be relatively high. The normal step difference of the display body constituent members ensures sufficient step followability.

Moreover, regarding the thickness of the adhesive layer 11, the upper limit is preferably 1000 μm or less, more preferably 400 μm or less, and particularly preferably 300 μm or less. If the upper limit of the thickness of the adhesive layer 11 is equal to or less than the above, the workability will be good. In addition, the adhesive layer 11 may be formed of a single layer, or may be formed by laminating a plurality of layers.

(2) Peel-off sheet

The peeling sheets 12a and 12b protect the adhesive layer 11 before using the adhesive sheet 1, and are peeled off when the adhesive sheet 1 (adhesive layer 11) is used. In the adhesive sheet 1 of this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

As the release sheets 12a and 12b, for example, a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or a polyterephthalene film can be used. Ethylene formate film, polyethylene naphthalate film, polybutylene terephthalate film, urethane film, ethylene ethyl acetate film, ionomer resin film, ethylene. (meth)acrylic acid copolymer film, ethylene. (Meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Moreover, these crosslinked films can also be used. In addition, these laminated films may also be used.

It is preferable that the peeling surfaces of the peeling sheets 12a and 12b (especially the surfaces in contact with the adhesive layer 11) are subjected to a peeling process. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. In addition, among the release sheets 12a and 12b, one release sheet is a heavy release type release sheet with a large release force, and the other release sheet is a heavy release release sheet. It is preferable that the release sheet be a light release type release sheet with a small release force.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

(3)Physical properties

(3-1) Step difference following rate

In the adhesive layer 11 of the adhesive sheet 1 of this embodiment, regarding the step following rate (%) represented by the following formula, the lower limit is preferably 20% or more, particularly preferably 25% or more, and further preferably 30% or more. . Furthermore, the upper limit of the step following rate is not particularly limited, but it is generally preferably 80% or less, and particularly preferably 70% or less.

Step following rate (%) = {(After the specified durability test, the height of the step that is filled without bubbles, floating, peeling, etc. (μm))/(Thickness of the adhesive layer)} × 100

In addition, the test method of the step following rate is as shown in the test example described later.

As described above, the adhesive layer of the adhesive sheet of this embodiment is bonded to the display component having a step on the surface of the side to be bonded. When the step tracking rate of the adhesive layer is within the above range, the adhesive layer can well follow the steps of the components of the display, and can suppress the generation of bubbles, floating, peeling, etc. near the steps even after the durability test, thereby suppressing the occurrence of Reflection loss of light. The step following rate within the above range can be achieved by appropriately adjusting the glass transition temperature (Tg) of the (meth)acrylate polymer (A) and the like.

(3-2) Haze value

The haze value of the adhesive layer 11 of the adhesive sheet 1 of this embodiment is preferably 5% or less, particularly preferably 3% or less, and further preferably 1% or less. If the haze value of the adhesive layer 11 is 5% or less, the transparency is very high and is suitable for optical applications. (For body display). In addition, the haze value in this manual is the value measured in accordance with JIS K7136:2000.

(3-3)Adhesion

Regarding the adhesive force of the adhesive sheet 1 of this embodiment to the soda-lime glass, the lower limit value is preferably 5N/25mm or more, particularly preferably 10N/25mm or more, and further preferably 15N/25mm or more. If the adhesive force of the adhesive sheet 1 is 5N/25mm or more, the blistering resistance will be more excellent. Furthermore, regarding the adhesive force of the adhesive sheet 1 of this embodiment to soda-lime glass, the upper limit is preferably 50N/25mm or less, more preferably 40N/25mm or less, and particularly preferably 35N/25mm or less. If the adhesive force of the adhesive sheet 1 is 50 N/25 mm or less, good reworkability can be obtained, and expensive display components can be reused when a lamination error occurs.

Here, the adhesive force in this specification basically refers to the adhesive force measured by the 180-degree peeling method in accordance with JIS Z0237:2009. The measurement sample is set to a width of 25 mm and a length of 100 mm, and the measurement sample is attached to the adherend. The material was pressurized at 0.5MPa and 50°C for 20 minutes, then left at normal pressure, 23°C, and 50%RH for 24 hours, and then measured at a peeling speed of 300mm/min.

(4) Manufacturing of adhesive sheets

As an example of manufacturing the adhesive sheet 1, the coating liquid of the adhesive composition P is applied to the peeling surface of one release sheet 12a (or 12b), and heat treatment is performed to thermally cross-link the adhesive composition P to form a coating. After the coating layer, the peeling surface of another peeling sheet 12b (or 12a) is overlapped with the coating layer. When a curing period is required, the above-mentioned coating layer becomes the adhesive layer 11 through the curing period. When a curing period is not required, the above-mentioned coating layer directly becomes the adhesive layer 11 . Thereby, the above-mentioned adhesive sheet 1 can be obtained. The heat treatment and aging conditions are as described above.

As another manufacturing example of the adhesive sheet 1, the coating liquid of the adhesive composition P is applied to the peeling surface of one release sheet 12a, and heat treatment is performed to thermally cross-link the adhesive composition P to form the coating. layer, thereby obtaining a release sheet 12a with a coating layer. Furthermore, the coating liquid of the above-mentioned adhesive composition P is applied to the release surface of the other release sheet 12b, and heat treatment is performed to thermally cross-link the adhesive composition P to form a coating layer, thereby obtaining a coating layer with the adhesive composition P. The peeling piece 12b of the fabric layer. Furthermore, the peeling sheet 12a with the coating layer and the peeling sheet 12b with the coating layer are bonded together so that the two coating layers are in contact with each other. When a curing period is required, the laminated coating layer becomes the adhesive layer 11 through the curing period. When a curing period is not required, the laminated coating layer directly becomes the adhesive layer 11 . By comparison, the above-mentioned adhesive sheet 1 can be obtained. According to this manufacturing example, stable manufacturing can be performed even when the adhesive layer 11 is thick.

As a method of applying the coating liquid of the adhesive composition P, for example, a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. can be used. .

[display body]

As shown in FIG. 2 , the display 2 of this embodiment has the following structure: a first display component 21 (one display component) with a step at least on the side to be bonded; a second display component member 22 (another display component); and the adhesive layer 11 located between them and bonding the first display component 21 and the second display component 22 to each other. In the display 2 of this embodiment, the surface of the first display component 21 on the adhesive layer 11 side has a step. Specifically, it has a step formed by the printing layer 3 .

The adhesive layer 11 in the above-mentioned display body 2 is the adhesive layer 1 of the aforementioned adhesive sheet 1. Adhesive layer 11.

Examples of the display body 2 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, etc., or a touch panel. Furthermore, the display body 2 may be a member constituting a part of these.

The first display component 21 may be a glass plate, a plastic plate, or the like, and is preferably a protective panel composed of a laminate or the like containing these. At this time, the printing layer 3 is generally formed in a frame shape on the adhesive layer 11 side of the first display component 21 .

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, and barium-containing glass. Strontium glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. The thickness of the glass plate is not particularly limited, but is usually 0.1~5mm, with 0.2~2mm being preferred.

The plastic board is not particularly limited, and examples thereof include acrylic boards, polycarbonate boards, and the like. The thickness of the plastic plate is not particularly limited, usually 0.2~5mm, and 0.4~3mm is preferred.

In addition, various functional layers (transparent conductive film, metal layer, silicon oxide layer, hard coat layer, anti-glare layer, etc.) can be provided on one or both sides of the above-mentioned glass plate or plastic plate, and optical components can also be laminated. Furthermore, the transparent conductive film and metal layer can be patterned.

The second display component 22 is an optical component to be attached to the first display component 21, a display module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescent Light emitting (organic EL) module etc.), an optical member as a part of a display module, or a laminate including a display module is preferred.

Examples of the optical member include anti-scattering films, polarizing plates (polarizing films), polarizers, retardation plates (retardation films), viewing angle compensation films, brightness enhancing films, contrast improvement films, and liquid crystal polymer films. Diffusion film, semi-transmissive reflective film, transparent conductive film, etc. Examples of the scattering prevention film include a hard coat film in which a hard coat layer is formed on one side of a base film.

The material constituting the printing layer 3 is not particularly limited, and known materials for printing can be used. The lower limit of the thickness of the printing layer 3 (that is, the height of the step) is preferably 3 μm or more, more preferably 5 μm or more, particularly 7 μm or more, and most preferably 10 μm or more. When the lower limit value is equal to or higher than the above, concealment such as electrical wiring cannot be seen from the observer side, and the concealment can be sufficiently ensured. Furthermore, the upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. When the upper limit value is the above or lower, deterioration of the step followability of the adhesive layer 11 with respect to the printing layer 3 can be prevented.

When manufacturing the above-mentioned display 2, as an example, one peeling sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the side of the first display component 21 where the printing layer 3 is present. face. At this time, since the adhesive layer 11 has excellent step followability, it is possible to suppress the occurrence of gaps or floating near the steps formed by the printing layer 3 .

Thereafter, another release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 and the second display component member 22 are bonded together. Furthermore, as another example, the first display component may be replaced 21 and the laminating sequence of the second display component member 22.

If the above display 2 is placed under high temperature and high humidity conditions (for example, 85° C., 85% RH), even if air leakage occurs from the first display component 21 and/or the second display component 22, the adhesive The layer 11 is also excellent in blistering resistance, so bubbling such as bubbles, floating, and peeling can be suppressed at the interface between the adhesive layer 11 and the first display component 21 and/or the second display component 22 .

Furthermore, the adhesive layer 11 has excellent step followability under high-temperature and high-humidity conditions. Therefore, when the display 2 is placed under high-temperature and high-humidity conditions (for example, 85° C., 85% RH), the occurrence of steps near the step can be suppressed. Bubbles, floating, peeling, etc.

The embodiments described above are described to facilitate understanding of the present invention and are not described to limit the present invention. Therefore, the requirements disclosed in the above embodiments are intended to include all design modifications and equivalents within the technical scope of the present invention.

For example, one or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 12a and/or 12b. Furthermore, the first display component member 21 may have steps other than the printing layer 3 . Furthermore, not only the first display component member 21 but also the second display component member 22 may have a step on the adhesive layer 11 side.

[Example]

Hereinafter, the present invention will be further described in detail through examples and the like, but the scope of the present invention is not limited to these examples.

[Example 1]

1. Preparation of (meth)acrylate polymers

(Meth)acrylate polymer (A) was prepared by copolymerizing 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate. The molecular weight of the (meth)acrylate polymer (A) was measured using the method described below. As a result, the weight average molecular weight (Mw) was 600,000.

2. Preparation of adhesive composition

Mix 100 parts by mass of the (meth)acrylate polymer (A) obtained in the above process 1 (solid content conversion value; the same below), polyrotaxane compound (B) (manufactured by Advanced Softmaterials Inc., product name "CELM High Polymer SH3400P", linear molecule: polyethylene glycol, cyclic molecule: α-cyclodextrin with hydroxypropyl and caprolactone chains, protective group: adamantyl ester, weight average molecular weight (Mw) 70 million, hydroxyl value 72 mgKOH/g) 5.0 parts by mass of trimethylolpropane-modified toluene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") as isocyanate cross-linking agent (C) 0.25 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.) as the reaction accelerator (D), 0.005 parts by mass of acetoacetone (manufactured by Tokyo Chemical Industry Co., Ltd.) as the reaction inhibitor ) 2.5 parts by mass and 0.25 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") as a silane coupling agent, stir thoroughly, and By diluting with methyl ethyl ketone, a coating solution of an adhesive composition having a solid content concentration of 35% by mass was obtained.

Among them, each component (solid content) of the adhesive composition when the (meth)acrylate polymer (A) is 100 parts by mass (solid content conversion value) Ingredient conversion values) are shown in Table 1. In addition, the details of the abbreviations and the like described in Table 1 are as follows.

[(Meth)acrylate polymer (A)]

2EHA: 2-ethylhexyl acrylate

MMA: methyl methacrylate

HEA: 2-hydroxyethyl acrylate

IBXA: Isobornyl acrylate

ACMO: 4-acrylomorphine

BA: n-butyl acrylate

MA: Methyl acrylate

[Isocyanate cross-linking agent (C)]

TDI: Trimethylolpropane-modified toluene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L")

XDI: Trimethylolpropane-modified xylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name "TD-75")

[Reaction accelerator (D)]

DBTDL: dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.)

TEA: Triethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.)

3. Manufacturing of adhesive sheets

On the release-treated surface of a heavy-release release sheet (manufactured by LINTEC Corporation, product name "SP-PET752150") obtained by subjecting one side of the polyethylene terephthalate film to a silicone-based release agent, use The blade coater applies the coating solution of the adhesive composition obtained in the above-mentioned process 2. and And the coating layer was heat-processed at 90 degreeC for 1 minute, and the coating layer was formed.

Next, the coating layer on the heavy release type release sheet obtained above was combined with a light release type release sheet (manufactured by LINTEC Corporation) obtained by subjecting one side of the polyethylene terephthalate film to a silicone release agent. , product name "SP-PET382120"), the light-peel release sheet is bonded so that the peel-off surface is in contact with the coating layer, and cured for 7 days at 23°C and 50% RH. The first adhesive sheet consists of a heavy-peel release sheet/adhesive layer (thickness: 25 μm)/light-peel release sheet.

Then, use a doctor blade coater to apply the coating solution of the adhesive composition obtained in the above-mentioned process 2 on one side of the polyethylene terephthalate film that is peeled off using a silicone-based release agent. After the release-processed surface of the type release sheet (manufactured by LINTEC Corporation, product name "SP-PET752150"), heat treatment was performed at 90° C. for 1 minute to form a coating layer (thickness: 25 μm). Similarly, use a knife coater to apply the coating solution of the adhesive composition obtained in the above-mentioned process 2 on the light surface of one side of the polyethylene terephthalate film that has been peeled off with a silicone-based release agent. After the release-processed surface of the release-type release sheet (manufactured by LINTEC Corporation, product name "SP-PET382120"), heat treatment was performed at 90° C. for 1 minute to form a coating layer (thickness: 25 μm).

Next, the heavy peeling type release sheet with the coating layer obtained above and the light peeling type peeling sheet with the coating layer obtained above are bonded together in such a manner that the two coating layers are in contact with each other, at 23 Aging was carried out for 7 days under conditions of ℃ and 50% RH, thereby producing a second adhesive sheet composed of a heavy-peel type release sheet/adhesive layer (thickness: 50 μm)/light-peel type release sheet structure.

In addition, the thickness of the above adhesive layer is based on JTS K7130 and The value is measured using a constant pressure thickness measuring device (manufactured by TECLOCK Corportion, product name "PG-02").

[Examples 2 to 17, Comparative Examples 1 to 3]

The types and proportions of each monomer constituting the (meth)acrylate polymer (A), the weight average molecular weight of the (meth)acrylate polymer (A), the mixing amount of the polyrotaxane compound (B), isocyanate The type and mixing amount of the cross-linking agent (C), the type and mixing amount of the reaction accelerator (D), the mixing amount of the reaction inhibitor, and the mixing amount of the silane coupling agent are changed from those shown in Table 1 to those in Example 1. Adhesion sheets are produced in the same manner.

Here, the weight average molecular weight (Mw) mentioned above is a weight average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

． GPC measuring device: TOSOH CORPORATION, HLC-8020

． GPC column (passed in the following order): Made by TOSOH CORPORATION

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

． Determination solvent: tetrahydrofuran

． Measuring temperature: 40℃

[Test Example 1] (Measurement of gel fraction)

The first adhesive sheet (thickness of adhesive layer: 25 μm) obtained in the Examples and Comparative Examples was cut into a size of 80 mm × 80 mm, and the adhesive layer was wrapped in a polyester mesh (mesh size 200). Use a precision balance to find its mass and subtract The mass of the above net alone is used to calculate the mass of the adhesive itself. Let the mass at this time be M1.

Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Thereafter, the adhesive was taken out and air-dried for 24 hours at a temperature of 23°C and a relative humidity of 50%. In addition, it was dried in an oven at 80°C for 12 hours. After drying, measure the mass using a precision balance and subtract the mass of the net alone to calculate the mass of the adhesive itself. Let the mass at this time be M2. The gel fraction (%) is expressed as (M2/M1)×100. The results are shown in Table 2.

[Test example 2] (Measurement of haze value)

For the adhesive layer of the first adhesive sheet (thickness of adhesive layer: 25 μm) obtained in the Examples and Comparative Examples, a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product) was used in accordance with JIS K7136:2000. Named "NDH-2000") to measure the haze value (%). The results are shown in Table 2.

[Test Example 3] (Measurement of adhesive force)

The light release type release sheet was peeled off from the first adhesive sheet (thickness of the adhesive layer: 25 μm) obtained in the Examples and Comparative Examples, and the exposed adhesive layer was bonded to the polyterephthalate having the easy-adhesive layer. An easy-adhesion layer of an ethylene formate (PET) film (manufactured by TOYOBO CO., LTD., product name "PET A4300", thickness: 100 μm) was used to obtain a laminate of a release sheet/adhesive layer/PET film. The obtained laminated body was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

The heavy-peel release sheet was peeled off from the above sample in an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and then Kurihara was used. Manufactory Inc. Pressurize the autoclave at 0.5MPa and 50°C for 20 minutes. Thereafter, after leaving it for 24 hours under the conditions of 23° C. and 50% RH, the adhesion was measured using a tensile testing machine (Tensilon, manufactured by ORIENTEC Co., LTD.) at a peeling speed of 300 mm/min and a peeling angle of 180 degrees. Force(N/25mm). Conditions other than those described here are measured in accordance with JIS Z 0237:2009. The results are shown in Table 2.

[Test Example 4] (Measurement of step following rate)

Ultraviolet curable ink (Teikoku Printing Inks Mfg. Co., Ltd.) was screen-printed on the surface of a glass plate (manufactured by NSG Precision Co, Ltd., product name "Corning Glass EAGLE XG", 90 mm in length x 50 mm in width x thickness 0.5 mm) ., product name "POS-911 ink"), so that the coating thickness becomes a frame shape of any one of 5μm, 10μm, 15μm and 20μm (outline: 90mm in length × 50mm in width, 5mm in width). Next, ultraviolet rays (80W/cm ² , two metal halide lamps, lamp height 15cm, belt speed 10~15m/min) are irradiated to harden the printed ultraviolet curable ink, thereby producing a printed structure with Glass plates with step differences (height of step: any one of 5μm, 10μm, 15μm and 20μm).

The light-peelable release sheet was peeled off from the second adhesive sheet (thickness of adhesive layer: 50 μm) obtained in the Examples and Comparative Examples, and the exposed adhesive layer was bonded to polyterephthalate having an easy-adhesive layer. An easy-adhesion layer of ethylene glycol film (manufactured by TOYOBO Co., Ltd., product name "PET A4300", thickness: 100 μm). Next, peel off the heavy-peel release sheet and uncover the adhesive layer. Thereafter, a laminating machine (manufactured by FUJIPLA Inc., product name "LPD3214") was used to laminate the above-described laminated body onto each of the stepped glass plates in such a manner that the adhesive layer covered the entire frame-shaped printing surface. Use this as a sample for evaluation Taste.

The obtained evaluation sample was subjected to autoclave treatment under conditions of 50°C and 0.5MPa for 30 minutes, and then left to stand at normal pressure, 23°C, and 50% RH for 24 hours. Next, it was stored under high temperature and high humidity conditions of 85° C. and 85% RH for 72 hours (durability test), and then the step followability was evaluated. The step followability is judged by whether the printing step is completely filled with the adhesive layer. If bubbles, floating, peeling, etc. are observed at the interface between the printing step and the adhesive layer, it is judged that the printing step cannot be followed. Here, the step following performance is evaluated as a step following rate (%) expressed by the following formula. The results are shown in Table 2.

Step following rate (%) = {(After the durability test, the height of the step in a filled state without bubbles, floating, peeling, etc. (μm))/(Thickness of the adhesive layer: 50 μm)} × 100

[Test Example 5] (Evaluation of foaming resistance)

A transparent conductive film using a polyethylene terephthalate film (manufactured by OIKE & Co., Ltd., ITO film, thickness: 125 μm) with a transparent conductive film made of tin-doped indium oxide (ITO) on one surface. The second adhesive sheet obtained in Examples and Comparative Examples was sandwiched between an acrylic sheet made of polymethylmethacrylate (PMMA) (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., product name "iupilon sheet MR200", thickness: 1 mm) (Thickness of adhesive layer: 50 μm) to obtain a laminate.

The obtained laminated body (sample) was subjected to autoclave treatment under conditions of 50° C. and 0.5 MPa for 30 minutes, and then left to stand at normal pressure, 23° C., and 50% RH for 24 hours. Then, it was stored under high temperature and high humidity conditions of 85°C and 85% RH for 72 hours. After that, visually confirm the adhesive layer and adherend bubbles at the interface, and the blistering resistance was evaluated based on the following criteria. The results are shown in Table 2.

◎...No air bubbles

○...When the top view area of the sample is taken as 100%, the proportion of the area occupied by bubbles is less than 10%

△......When the top view area of the sample is taken as 100%, the proportion of the area occupied by bubbles is between 10% and less than 50%

×...When the top view area of the sample is taken as 100%, the proportion of the area occupied by bubbles is more than 50%

【Table 2】

As can be seen from Table 2, the adhesive sheet obtained in the Example was excellent in both step followability and blistering resistance.

[Industrial availability]

The adhesive sheet of the present invention can be suitably used, for example, for bonding a protective panel with a step to a desired display component.

1‧‧‧Adhesive sheet

11‧‧‧Adhesive layer

12a, 12b‧‧‧Peel-off sheet

Claims (8)

An adhesive composition, characterized by containing: (meth)acrylate polymer (A), as a monomer unit constituting the polymer, including a hydroxyl-containing monomer; a polyrotaxane compound (B), having a hydroxyl-containing monomer The cyclic oligosaccharide as the reactive group serves as the cyclic molecule; the isocyanate cross-linking agent (C); the reaction accelerator (D) to promote the polyurethanization reaction; and the reaction inhibitor, the aforementioned polyrotaxane compound (B) The content of the reaction accelerator (D) is 0.5 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the (meth)acrylate polymer (A). (A) 100 parts by mass is 0.001 parts by mass or more and 1.0 parts by mass or less. The adhesive composition described in claim 1, wherein the (meth)acrylate polymer (A) contains 3% by mass or more and 30% by mass as a monomer unit constituting the polymer. The following aforementioned hydroxyl-containing monomers. An adhesive formed by cross-linking the adhesive composition described in Item 1 or 2 of the patent application. For example, the adhesive agent described in Item 3 of the patent application scope has a gel fraction of more than 30% and less than 90%. An adhesive sheet, which has an adhesive layer, and the aforementioned adhesive layer is used to be attached to The surface at least on the side to be bonded has one display component and another display component with a step difference, and is characterized in that the aforementioned adhesive layer is composed of the adhesive described in Item 3 of the patent application. For example, in the adhesive sheet described in Item 5 of the patent application, the step following rate of the adhesive layer is more than 20%. The adhesive sheet according to claim 5, wherein the adhesive sheet has two release sheets, and the adhesive layer is sandwiched by the release sheets in contact with the release surfaces of the two release sheets. A display body, which is provided with: one display body constituent member, which has a step at least on the surface of the side to be bonded; another display body constituent member; and an adhesive layer, which is mutually bonded to the aforementioned one display body constituent member and the aforementioned other display body member. The display body is a constituent component of the display body, and the characteristic of the display body is that the adhesive layer is the adhesive layer of the adhesive sheet described in Item 5 of the patent application.

Images