JP2014088533A - Adhesive composition and adhesive sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition capable of suppressing, when bonding a polycarbonate film with another component through an adhesive agent, a lifting or separation due to a gas composition generated from the polycarbonate film, and an adhesive sheet using the same.SOLUTION: An adhesive composition includes at least an acrylic adhesive agent and a crosslinking agent. The crosslinking agent is hexamethylene diisocyanate. The hexamethylene diisocyanate of 1.3-3.2 pts.mass is included with regard to the acrylic adhesive agent of 100 pts.mass.

Description

  The present invention relates to a pressure-sensitive adhesive composition. More specifically, when a polycarbonate film is bonded to another member via a pressure-sensitive adhesive, it suppresses floating and peeling caused by gas components generated from the polycarbonate film. The present invention relates to an adhesive composition that can be used, and an adhesive sheet using the same.

  In recent years, touch panels capable of intuitively operating electronic devices have been employed in so-called mobile products such as portable information terminals and electronic dictionaries. The touch panel is incorporated in a liquid crystal display element, an organic EL element, or the like as a module substrate in which a transparent conductive film such as ITO is laminated on a glass serving as a surface protective substrate via an adhesive.

  In addition to excellent transparency, the adhesive used for the module substrate has a characteristic that part of the adhesive does not remain on the adherend during rework (hereinafter also referred to as reworkability), and high temperature The durability is required such that the module substrate is not peeled off even under high humidity and bubbles are not generated in the substrate. As such an adhesive, Japanese Patent Application Laid-Open No. 2005-154882 (Patent Document 1) provides an adhesive that is tack-free and excellent in durability by adding isocyanate or the like to an acrylic adhesive. Has been proposed. JP 2010-95603 A (Patent Document 2) proposes a pressure-sensitive adhesive obtained by adding a specific isocyanurate to an acrylic copolymer.

  By the way, since the above-mentioned module substrate uses glass, there is a possibility that the glass may be damaged by dropping or the like. For this reason, tempered glass obtained by chemically treating the glass itself is used, but the cost of the module substrate is increased. Therefore, it has been proposed to use a resin film such as a polyester film as the surface protective substrate or the ITO conductive film substrate.

Japanese Patent Laid-Open No. 2005-154782 JP 2010-95603 A

  As described above, when the glass of the module substrate is replaced with a polyester film or the like, the damage prevention property due to dropping is remarkably improved, but the birefringence characteristic of the resin film is high, so that the image visibility is lowered. A polycarbonate film is known as a resin film having a low birefringence and excellent impact resistance. By replacing the glass of the module substrate with a polycarbonate film, a module substrate with high damage prevention and excellent visibility is obtained. It can be realized.

  However, the present inventors have now applied the acrylic adhesive used in the conventional module substrate to the polycarbonate film, and when the module substrate is placed in a high temperature environment, the gas generated from the polycarbonate causes the module substrate to be in the module substrate. It was found that floating and peeling occur. And it was found that by using a pressure-sensitive adhesive with a specific amount of hexamethylene diisocyanate added as a crosslinking agent to an acrylic pressure-sensitive adhesive, the module substrate can be effectively prevented from floating and peeling even when applied to a polycarbonate film. It was. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive composition that can suppress floating and peeling caused by gas components generated from a polycarbonate film when the polycarbonate film is bonded to another member via the pressure-sensitive adhesive. And an adhesive sheet using the same.

The pressure-sensitive adhesive composition according to the present invention is a pressure-sensitive adhesive composition comprising at least an acrylic pressure-sensitive adhesive and a crosslinking agent,
The crosslinking agent is hexamethylene diisocyanate;
The hexamethylene diisocyanate is contained in an amount of 1.3 to 3.2 parts by mass with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive.

  Moreover, in the embodiment of this invention, it is preferable that the gel fraction of the adhesive composition after bridge | crosslinking the said acrylic adhesive and the said crosslinking agent is 70 to 85%.

In an embodiment of the present invention, the loss tangent (tan δ ₁₀₀ ) value at 100 ° C. of the pressure-sensitive adhesive composition is preferably in the range of 0.15 to 0.32.

  In an embodiment of the present invention, the acrylic pressure-sensitive adhesive comprises a (meth) acrylic acid ester monomer, a hydroxyl group-containing (meth) acrylate monomer and / or a carboxyl group-containing (meth) acrylate monomer. It is preferable to consist of a copolymer.

  In the embodiment of the present invention, the copolymer preferably has a mass average molecular weight in the range of 250,000 to 1,500,000.

  The pressure-sensitive adhesive sheet according to another aspect of the present invention is a pressure-sensitive adhesive sheet obtained by laminating a first release paper, a pressure-sensitive adhesive layer, and a second release paper in this order, and the pressure-sensitive adhesive layer is the above-mentioned adhesive layer. It consists of an agent composition.

Moreover, the manufacturing method of the bonding body by another aspect of this invention is a method of manufacturing a bonding body using the said adhesive sheet,
From the pressure-sensitive adhesive sheet, the first release paper is peeled and removed to expose the pressure-sensitive adhesive layer,
An adhesive layer is bonded to the polycarbonate resin film that is the adherend,
From the pressure-sensitive adhesive sheet, the second release paper is peeled off, the other adherend and the pressure-sensitive adhesive layer are bonded, and the polycarbonate resin film and the other adherend are bonded.
It is meant to include.

  Moreover, in this invention, the bonding body obtained by the said manufacturing method is also provided.

  ADVANTAGE OF THE INVENTION According to this invention, when a polycarbonate film is bonded with another member via an adhesive, the adhesive composition which can suppress the float and peeling resulting from the gas component generated from a polycarbonate film is implement | achieved. be able to.

It is the cross-sectional schematic by one Embodiment of the adhesive sheet by this invention. It is a cross-sectional schematic diagram by one embodiment of the bonding body using the adhesive sheet by this invention.

<Adhesive composition>
The pressure-sensitive adhesive composition according to the present invention contains an acrylic pressure-sensitive adhesive and hexamethylene diisocyanate as a crosslinking agent as essential components. Hereinafter, each component which comprises an adhesive composition is demonstrated.

  As long as the acrylic pressure-sensitive adhesive contained in the pressure-sensitive adhesive composition according to the present invention can react with hexamethylene diisocyanate to be described later without cross-linking, a conventionally known acrylic pressure-sensitive adhesive can be used without limitation. For example, an acrylic pressure-sensitive adhesive mainly composed of (meth) acrylic acid ester can be suitably used. In addition, in this specification, (meth) acrylic acid shall mean acrylic acid and / or methacrylic acid. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, and n-octyl (meta ) Acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, i-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate Stearyl (meth) acrylate and the like can be used. These acrylic acid esters may contain 1 type (s) or 2 or more types.

  In this invention, it is preferable to use what copolymerized the hydroxyl-containing (meth) acrylate monomer and / or the carboxyl group-containing (meth) acrylate monomer in addition to the above (meth) acrylic acid ester.

  Examples of the hydroxyl group-containing (meth) acrylate monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-butyl (meth) acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4-trimethyl- 3-hydroxypentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (meth) acrylate, glycerin mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, poly (ethylene glycol) Lumpur - propylene glycol) mono (meth) acrylate, N- methylol acrylamide, allyl alcohol, methallyl alcohols. One or more of these hydroxyl group-containing (meth) acrylate monomers may be contained. By including the hydroxyl group-containing (meth) acrylate monomer as described above, the reworkability of the acrylic pressure-sensitive adhesive can be improved.

  Examples of carboxyl group-containing (meth) acrylate monomers include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, monohydroxyethyl (meth) acrylate succinate , Monohydroxyethyl maleate (meth) acrylate, monohydroxyethyl fumarate (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) acrylic And acid dimer, ω-carboxy-polycaprolactone mono (meth) acrylate, and the like. One or more of these carboxyl group-containing (meth) acrylate monomers may be contained.

  The hydroxyl group-containing (meth) acrylate monomer and carboxyl group-containing (meth) acrylate monomer described above may be added to the (meth) acrylate ester in consideration of the adhesiveness and reworkability of the acrylic pressure-sensitive adhesive. it can. It is preferable to add 0.1 to 20% of a hydroxyl group-containing (meth) acrylate monomer on a mass basis with respect to the (meth) acrylic acid ester monomer. Moreover, it is preferable to add 0.1-20% of carboxyl group-containing (meth) acrylate monomers on a mass basis with respect to the (meth) acrylic acid ester monomer.

  In the present invention, in addition to the monomers described above, glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl vinyl ether, 3,4-epoxycyclohexyl vinyl ether, glycidyl (meta ) Glycidyl group-containing (meth) acrylate monomers such as allyl ether and 3,4-epoxycyclohexyl (meth) allyl ether, acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-tert-butylacrylamide, N-o Chill acrylamide may be included containing amide groups of diacetone acrylamide (meth) acrylate monomer.

  The acrylic pressure-sensitive adhesive (copolymer) used in the present invention can be obtained by polymerizing the above monomers by a method such as ordinary solution polymerization, bulk polymerization, emulsion polymerization or suspension polymerization. However, it is preferable to manufacture by the solution polymerization from which the said acrylic adhesive is obtained as a solution. By obtaining the acrylic pressure-sensitive adhesive as a solution, it can be used as it is for the production of the pressure-sensitive adhesive composition of the present invention.

  Examples of the solvent used for the solution polymerization include organic solvents such as ethyl acetate, toluene, n-hexane, acetone, and methyl ethyl ketone. Examples of the polymerization initiator used in the polymerization include peroxides such as benzoyl peroxide and lauryl peroxide, azobis compounds such as azobisisobutyronitrile and azobisvaleronitrile, and polymer azo polymerization initiators. These can be used alone or in combination. Moreover, in the said superposition | polymerization, in order to adjust the molecular weight of an acrylic adhesive, a conventionally well-known chain transfer agent can be used.

  The mass average molecular weight of the acrylic copolymer described above is preferably in the range of 250,000 to 1,500,000, more preferably in the range of 400,000 to 1,000,000. When the mass average molecular weight is less than 250,000, the adhesive property of the pressure-sensitive adhesive composition may be inferior, and when the mass average molecular weight exceeds 1,500,000, the coating property of the pressure-sensitive adhesive composition is deteriorated. The mass average molecular weight can be measured by GPC (gel permeation chromatography) using a polystyrene standard sample.

  Next, the crosslinking agent will be described. The pressure-sensitive adhesive composition according to the present invention contains hexamethylene diisocyanate as a crosslinking agent in addition to the above-mentioned acrylic pressure-sensitive adhesive. When hexamethylene diisocyanate functions as a crosslinking agent for an acrylic pressure-sensitive adhesive, when the polycarbonate film is laminated via the pressure-sensitive adhesive, it is possible to effectively suppress gas from the polycarbonate film generated in a high-temperature environment. . The reason for this is not clear, but can be considered as follows. Hexamethylene diisocyanate is less reactive than tolylene diisocyanate and xylene diisocyanate, so that it is easy to control the gel fraction (degree of crosslinking) as described later, and the gel fraction can be in the range of 70 to 85%. . Further, unlike tolylene diisocyanate and xylene diisocyanate, hexamethylene diisocyanate does not have a ring structure, so that it is easy to control the viscoelastic properties of the pressure-sensitive adhesive. It can be made into the range of 15-0.32. As a result, it is considered that foaming due to gas generation can be suppressed while maintaining the adhesive strength. Moreover, since hexamethylene diisocyanate does not have a ring structure, yellowish color (b *) is low, and even when cyanate is used as a crosslinking agent, the pressure-sensitive adhesive composition can be maintained colorless and transparent.

  Hexamethylene diisocyanate is contained in a proportion of 1.3 to 3.2 parts by mass with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive described above. When the content of hexamethylene diisocyanate is less than 1.3 parts by mass, the gel fraction of the pressure-sensitive adhesive composition is 70% or less, and gas components generated from the polycarbonate at high temperatures cannot be suppressed, and floating or foaming occurs. There is. On the other hand, when the content of hexamethylene diisocyanate exceeds 3.2 parts by mass, the viscosity of the pressure-sensitive adhesive composition is rapidly increased and gelled, and the coatability may be deteriorated.

  The pressure-sensitive adhesive composition according to the present invention may contain additives such as an ultraviolet absorber and an antioxidant. As the ultraviolet absorber, known compounds can be used, and examples thereof include organic ultraviolet absorbers such as benzotriazole, benzophenone, salicylate, and benzoate, and inorganic ultraviolet absorbers.

  In addition, by including an antioxidant in the pressure-sensitive adhesive composition, the color change in the visible light region and the color change in the near-infrared region can be further suppressed, and the transparency can be maintained. The pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive) may be deteriorated by ultraviolet rays or temperature, and the oxidation of the acrylic pressure-sensitive adhesive can be suppressed by the antioxidant, so that transparency can be maintained. . Examples of the antioxidant include phenol-based, amine-based, sulfur-based, and phosphorus-based antioxidants.

  In addition, the pressure-sensitive adhesive composition may include, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slip properties, mold release properties, flame retardancy, antifungal properties. For the purpose of improving and modifying properties, electrical properties, strength, etc., for example, lubricants, plasticizers, fillers, fillers, antistatic agents, antiblocking agents, crosslinking agents, light stabilizers, dyes, pigments, etc. Other colorants, etc. may be added. Further, if necessary, a coupling agent such as silane, titanium, and aluminum can be further included.

  The pressure-sensitive adhesive composition according to the present invention can be prepared by mixing the above-described components and kneading and dispersing as necessary. The mixing or dispersing method is not particularly limited, and a usual kneading and dispersing machine such as a two-roll mill, a three-roll mill, a pebble mill, a tron mill, a Szegvari attritor, a high-speed impeller disperser, a high-speed stone mill, A high speed impact mill, a desper, a high speed mixer, a ribbon blender, a kneader, an intensive mixer, a tumbler, a blender, a desperser, a homogenizer, an ultrasonic disperser, and the like can be applied. In addition, in order to adjust the viscosity of the pressure-sensitive adhesive coating solution, a diluent solvent may be added to mix each component.

  The above-mentioned pressure-sensitive adhesive composition preferably has a gel fraction in the range of 70 to 85%. When the degree of crosslinking of the acrylic pressure-sensitive adhesive is small and the gel fraction is less than 70%, when a bonded body of a polycarbonate resin film is produced through the pressure-sensitive adhesive, the gas component may cause floating or peeling. is there. On the other hand, if the gel fraction exceeds 85%, the viscosity of the pressure-sensitive adhesive composition may increase and the coatability may deteriorate. The gel fraction is determined by dissolving the pressure-sensitive adhesive composition with an organic solvent such as toluene, and then collecting the insoluble component (gel component) remaining in the solvent to obtain the gel component contained in the pressure-sensitive adhesive composition. It shall mean mass ratio.

The pressure-sensitive adhesive composition preferably has a loss tangent (tan δ ₁₀₀ ) value at 100 ° C. in the range of 0.15 to 0.32. When tan δ ₁₀₀ is in this range, the gas generated in the polycarbonate laminate can be effectively suppressed, so that the problem of floating or peeling is solved. The loss tangent is obtained from the loss elastic modulus / storage elastic modulus. The loss elastic modulus represents the viscous property of the material (resin composition), and is related to the amount of energy that the material being deformed dissipates as heat, and serves as an index for relaxing vibration energy. The storage elastic modulus component is the equilibrium elastic modulus of the rubber-like elastic region, and is a factor related to the crosslinking density of the pressure-sensitive adhesive composition. The value of loss elastic modulus / storage elastic modulus can be measured by a conventional method using a dynamic viscoelasticity measuring apparatus.

  With conventional adhesives, when gas is generated from the polycarbonate resin film, gas is bubbled at the interface between the resin film and the adhesive layer to apply stress to the adhesive, and the stress is converted into heat to soften the adhesive. And bubbles were formed by the deformation of the adhesive. In the pressure-sensitive adhesive composition according to the present invention, since the loss tangent is in the above range, the pressure generated by gas generation is hardly converted into heat, so the pressure-sensitive adhesive does not soften and bubbles are prevented from being formed in the pressure-sensitive adhesive. It is thought that there is.

When the value of the loss tangent (tan δ ₁₀₀ ) at 100 ° C. of the pressure-sensitive adhesive composition is less than 0.15, when stress acts on the pressure-sensitive adhesive, the stress is not appropriately converted into heat, and the pressure-sensitive adhesive composition As a result of deformation due to stress, as a result of gas generation from the polycarbonate resin film as described above, bubbles are formed in the pressure-sensitive adhesive layer. On the other hand, when the value of the loss tangent (tan δ ₁₀₀ ) exceeds 0.32, the stress is almost converted into heat, and the pressure-sensitive adhesive composition is softened by the heat, and as a result, gas is generated from the polycarbonate resin film. , Bubbles will be formed in the adhesive layer. As described above, in the present invention, gas generation from the polycarbonate resin film is effectively suppressed by setting the loss tangent range in which stress and thermal deformation are balanced.

<Adhesive sheet>
As shown in FIG. 1, the pressure-sensitive adhesive sheet according to the present invention has a layer structure in which a first release paper and a second release paper are provided on both surfaces of a pressure-sensitive adhesive layer made of the above-described pressure-sensitive adhesive composition. In the present specification, the first release paper 21A and the second release paper 21B are collectively referred to as release paper 21.

  The pressure-sensitive adhesive sheet 1 is obtained by applying the pressure-sensitive adhesive composition 13 to the first release paper 21 described later and drying it, and then bonding the second release paper 21B to the application surface. The thickness of the pressure-sensitive adhesive layer is preferably about 100 μm to 200 μm. If the thickness of the pressure-sensitive adhesive layer (the coating amount of the pressure-sensitive adhesive composition) is too thin, it may not be possible to suppress floating or peeling due to gas generation. On the other hand, even if the thickness exceeds 200 μm, the effect of suppressing floating and peeling does not improve any more, leading to an increase in cost.

  The method for applying the pressure-sensitive adhesive composition to the release paper is not particularly limited. For example, roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coat, blade Coating, bar coating, wire bar coating, die coating, lip coating, dip coating, etc. can be applied. The pressure-sensitive adhesive composition may be applied to the release surface of the first release paper 21A by the above coating method and dried, and then the second release paper 21B may be bonded.

  The first release paper 21A and the second release paper 21B may be the same or different. As the release paper 21, conventionally known ones such as a release film, a separate paper, a separate film, a separate paper, a release film, and a release paper can be suitably used. Moreover, you may use what formed the release layer in the single side | surface or both surfaces of base materials for release paper, such as quality paper, a coated paper, an impregnation paper, a plastic film. The release layer is not particularly limited as long as it is a material having releasability. For example, silicone resin, organic resin-modified silicone resin, fluororesin, aminoalkyd resin, melamine resin, acrylic resin, polyester resin, etc. There is. These resins can be used in any of emulsion type, solvent type and solventless type.

  The release layer is formed by applying a coating liquid in which a release layer component is dispersed and / or dissolved on one side of a release paper base film, followed by heat drying and / or curing. As a coating method of the coating liquid, a known and arbitrary coating method can be applied, for example, roll coating, gravure coating, spray coating and the like. Moreover, you may form a release layer in the whole surface or a part of at least single side | surface of a base film as needed.

  The peeling force of the first and second release papers is preferably about 1 to 2000 mN / cm, more preferably 100 to 1000 mN / cm, with respect to the pressure-sensitive adhesive sheet. When the release force of the release layer is less than 1 mN / cm, the release force from the pressure-sensitive adhesive sheet or the adherend is weak, and it peels off or partially floats. Moreover, when larger than 2000 mN / cm, the peeling force of a release layer is strong and it is hard to peel. From the viewpoint of stable releasability and processability, addition and / or polycondensation-type curable silicone resins for release paper, which are mainly composed of polydimethylsiloxane, are preferred.

  According to the present invention, as shown in FIG. 2, using the above-described pressure-sensitive adhesive sheet 1, the polycarbonate resin film 30 is bonded to another adherend 40 via the pressure-sensitive adhesive layer 11 to form a module substrate. it can. In the present invention, even when the bonded body is placed in a high temperature environment, the module substrate is excellent in appearance with the polycarbonate resin film 30 as a base material, which does not float or peel off due to gas generated from the polycarbonate resin film 30 or the like. Can be obtained.

  Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to the contents of these examples.

<Preparation of pressure-sensitive adhesive composition>
An acrylic pressure-sensitive adhesive was prepared as follows. Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen gas. Thereafter, 100 parts by mass of butyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, 10 parts by mass of N, N-diethylacrylamide and 60 parts by mass of ethyl acetate were added to the reactor. Thereafter, 0.1 parts by mass of azobisisobutyronitrile was added as a polymerization initiator, and the mixture was allowed to react in a nitrogen gas stream at 65 ° C. for 5 hours while stirring. This was an acrylic adhesive having a mass average molecular weight of 600,000. A solution of the agent was obtained.

With respect to 100 parts by mass of the obtained acrylic pressure-sensitive adhesive, the isocyanate crosslinking agent shown in the following Table 1 is blended at a ratio shown in the following Table 1, and ethyl acetate (product name: ethyl acetate: 10 parts by mass (manufactured by DIC Graphics) was blended and mixed with a stirrer to obtain an adhesive composition. In Table 1 below,
Coronate HK is hexamethylene diisocyanate (isocyanurate type) manufactured by Nippon Polyurethane Industry.
Coronate HX is hexamethylene diisocyanate (isocyanurate type) manufactured by Nippon Polyurethane Industry.
Coronate HL is a hexamethylene diisocyanate (adduct type) manufactured by Nippon Polyurethane Industry.
Coronate L is Tolylene diisocyanate (adduct type) manufactured by Nippon Polyurethane Industry.
K341 is xylene diisocyanate (isocyanurate type) manufactured by Seiden Chemical,
Each is shown.

  Next, it was applied with an applicator so that the thickness after drying would be the value shown in Table 1 on a 50 μm thick PET carrier film (product name: Therapy BX9 (RX), manufactured by Toray Film Co., Ltd.) subjected to silicone release treatment. 50 μm thick PET carrier film (product name: Therapy MFA (RX), manufactured by Toray Film Processing) Was laminated with a rubber roller, and an adhesive sheet was produced by performing an aging treatment in an environment of 40 ° C. for 3 days.

<Production of bonded body>
The carrier film was peeled off from the obtained pressure-sensitive adhesive sheet and laminated using a rubber roll on the surface on which an easy-adhesion layer of a 100 μm thick polyester film (product name Cosmo Shine A4100: manufactured by Toyobo Co., Ltd.) was formed. The laminated adhesive sheet was cut into 25 mm × 200 mm to obtain test pieces. The other carrier film was peeled off from this test piece, and the surface of the adhesive layer was a 2 kg roller on the surface on which the hard coat of a 1.0 mm thick polycarbonate plate (product name: Iupilon sheet MR58) on which the hard coat was formed was formed. The laminated body was obtained by laminating using.

<Gas generation suppression evaluation>
The obtained bonded body is heat-treated in an autoclave apparatus under conditions of 0.5 MPa, 50 ° C. and 30 minutes, and then put into an oven at a temperature of 100 ° C. and left for 100 hours, and then floated or peeled off on the bonded body. It was confirmed visually that there were no defects.

<Measurement of loss tangent>
Loss tangent (tan δ) is measured using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments, and a dynamic viscoelasticity measurement method (attachment mode: compression mode, frequency: compliant with JIS K7244-1). 1 Hz, temperature: −50 to 150 ° C., heating rate: 5 ° C./min).

<Gel fraction measurement>
Both carrier films were peeled off from the pressure-sensitive adhesive sheet cut to 500 mm × 500 mm, and the mass (J ⁱⁿⁱ ) of the pressure-sensitive adhesive alone was measured. Next, the pressure-sensitive adhesive alone was put into 300 g of a toluene solution and allowed to stand for 24 hours in an environment of normal humidity and normal temperature. The toluene solution containing the pressure-sensitive adhesive was filtered through 200 mesh, and the gel remaining on the mesh was removed. It was dried in a 160 ° C. oven for 6 hours to completely volatilize the toluene in the gel. The mass of the gel (J ^aft ) is measured and the following formula:
Gel fraction = J ^aft / J ⁱⁿⁱ × 100
The gel fraction was evaluated.

The results were as shown in Table 2 below.

Claims (8)

An adhesive composition comprising at least an acrylic adhesive and a crosslinking agent,
The crosslinking agent is hexamethylene diisocyanate;
1.3-3.2 mass parts of said hexamethylene diisocyanate is contained with respect to 100 mass parts of said acrylic adhesives, The adhesive composition characterized by the above-mentioned.   The pressure-sensitive adhesive composition according to claim 1, wherein a gel fraction of the pressure-sensitive adhesive composition after the acrylic pressure-sensitive adhesive and the crosslinking agent are crosslinked is 70 to 85%. The pressure-sensitive adhesive composition according to claim 2, wherein a value of a loss tangent (tan δ ₁₀₀ ) at 100 ° C of the pressure-sensitive adhesive composition is in a range of 0.15 to 0.32.   The acrylic pressure-sensitive adhesive comprises a copolymer of a (meth) acrylic acid ester monomer and a hydroxyl group-containing (meth) acrylate monomer and / or a carboxyl group-containing (meth) acrylate monomer. The adhesive composition as described in any one of 1-3.   The pressure-sensitive adhesive composition according to claim 4, wherein the copolymer has a mass average molecular weight in the range of 250,000 to 1,500,000.   It is an adhesive sheet formed by laminating a first release paper, an adhesive layer, and a second release paper in this order, and the adhesive layer is according to any one of claims 1 to 5. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive composition. A method for producing a bonded body using the pressure-sensitive adhesive sheet according to claim 6,
From the pressure-sensitive adhesive sheet, the first release paper is peeled and removed to expose the pressure-sensitive adhesive layer,
An adhesive layer is bonded to the polycarbonate resin film that is the adherend,
From the pressure-sensitive adhesive sheet, the second release paper is peeled off, the other adherend and the pressure-sensitive adhesive layer are bonded, and the polycarbonate resin film and the other adherend are bonded.
Comprising a method.   The bonding body obtained by the method of Claim 7.

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