JP2014234460A - Adhesive composition and adhesive sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition which is excellent in shock resistance and capable of preventing blisters or peeling and of maintaining hard coat performance of a shatterproof film, and to provide an adhesive sheet using the composition.SOLUTION: The adhesive composition comprises at least an acrylic adhesive and a crosslinking agent. The acrylic adhesive is a polymer comprising a (meth)acrylate as a monomer; and the polymer has a glass transition temperature ranging from -20 to 10°C. The adhesive composition prepared by after crosslinking the acrylic adhesive with the crosslinking agent shows a storage modulus of 1.0×10to 2.4×10Pa at 25°C.

Description

  The present invention relates to a pressure-sensitive adhesive composition, and more particularly to a pressure-sensitive adhesive composition used for a hard coat resin film with a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet using the same.

  A so-called mobile product such as an information portable terminal or an electronic dictionary employs a touch panel capable of intuitively operating an electronic device. In recent years, these mobile products are increasingly required to be thinner or lighter, and the outermost surface of the touch panel (that is, the surface on the viewer side) uses a thin tempered glass substrate from a conventional plastic plate. It has become like this. Therefore, the anti-scattering film is bonded on the surface of the tempered glass substrate, and the tempered glass substrate is devised so that the glass does not scatter even when it is damaged.

  In addition, since mobile products that use touch panels rub the display screen with fingers or pens on a daily basis, anti-scattering films that are bonded to the surface of a tempered glass substrate require scratch resistance to prevent damage. Is done. Therefore, a hard coat film having a predetermined pencil hardness is used as a scattering prevention film. Such a hard coat scattering prevention film is bonded to the surface of the tempered glass substrate via an adhesive.

  Normally, when sticking a hard coat scattering prevention film to a tempered glass substrate for a touch panel, the hard coat scattering prevention film with an adhesive layer is cut according to the size of the tempered glass substrate of a predetermined size. In addition, the cut material is bonded to a tempered glass substrate via an adhesive (for example, JP 2008-216913 A).

In addition to being excellent in impact resistance, the adhesive used for pasting the tempered glass substrate and the hard coat scattering prevention film as described above cuts the hard coat scattering prevention film with the adhesive layer. In this case, it is required that the peripheral edge does not float or peel off. For such a problem, Japanese Patent Application Laid-Open No. 2011-168852 uses a relatively soft adhesive having a storage elastic modulus at 0 ° C. of 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ Pa. In addition, it has been proposed that a hard coat scattering prevention film with an adhesive layer that is excellent in suitability for cutting without peeling or peeling off can be obtained.

Moreover, in JP 2009-110026 A, impact resistance is improved by using an acrylic pressure-sensitive adhesive having a storage elastic modulus at 20 ° C. in the range of 7 × 10 ⁶ to 1 × 10 ³ Pa. It has been proposed.

JP 2008-216913 A Japanese Unexamined Patent Publication No. 2011-168652 JP 2009-110026 A

  In the case of using the above-mentioned pressure-sensitive adhesive, the present inventors bonded a hard coat-type scattering prevention film having a predetermined pencil hardness to a tempered glass substrate via the pressure-sensitive adhesive. It has been found that the pencil hardness is reduced, and the reason for the reduction in the pencil hardness is due to the adhesive interposed between the tempered glass substrate and the hard coat scattering prevention film.

  And the present inventors now add a specific monomer to the (meth) acrylic acid ester monomer, which is the main component of the acrylic pressure-sensitive adhesive, to raise the glass transition temperature of the pressure-sensitive adhesive. By making it into the range, it was found that a pressure-sensitive adhesive having excellent impact resistance and preventing floating and peeling and maintaining the hard coat performance of the anti-scattering film was obtained. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive composition that is excellent in impact resistance, can prevent floating and peeling, and can maintain the hard coat performance of the anti-scattering film, and a pressure-sensitive 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 acrylic pressure-sensitive adhesive is a polymer containing (meth) acrylic acid ester as a monomer,
The glass transition temperature of the polymer is in the range of −20 to 10 ° C.,
A storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive composition after the acrylic pressure-sensitive adhesive is cross-linked with a cross-linking agent is 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa. .

  In an embodiment of the present invention, the acrylic pressure-sensitive adhesive preferably comprises (meth) acrylic acid ester and acrylonitrile as monomers.

  In an embodiment of the present invention, the acrylic pressure-sensitive adhesive preferably comprises (meth) acrylic acid ester and acrylonitrile as monomers.

  In the embodiment of the present invention, it is preferable that the acrylic pressure-sensitive adhesive further contains a hydroxyl group-containing (meth) acrylate and / or a carboxyl group-containing (meth) acrylate as a monomer.

  In an embodiment of the present invention, the cross-linking agent is an isocyanate-based cross-linking agent, and is preferably included in a solid ratio of 0.2 to 2.0% by mass with respect to the acrylic pressure-sensitive adhesive.

  In an embodiment of the present invention, the cross-linking agent is an epoxy-based cross-linking agent, and is preferably included in a solid ratio of 0.02 to 2.0% by mass with respect to the acrylic pressure-sensitive adhesive.

  In the embodiment of the present invention, the glass transition temperature after crosslinking the acrylic pressure-sensitive adhesive composition is preferably 20 to 40 ° C.

  In an embodiment of the present invention, the (meth) acrylic acid ester is preferably butyl acrylate.

  The pressure-sensitive adhesive sheet according to another aspect of the present invention is a pressure-sensitive adhesive sheet comprising a release paper and a pressure-sensitive adhesive layer provided on the release paper, wherein the pressure-sensitive adhesive layer is composed of the above-mentioned adhesive composition. It is.

  Moreover, the hard coat resin film with an adhesive layer by another aspect of this invention is bonded by the adhesive layer of the said adhesive sheet to a hard coat resin film.

In the present invention, acrylonitrile is copolymerized with the (meth) acrylic acid ester monomer, which is the main component of the acrylic pressure-sensitive adhesive, and the pressure-sensitive adhesive composition after being crosslinked with a crosslinking agent at 25 ° C. By setting the storage elastic modulus in the range of 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa, it is excellent in impact resistance and can prevent floating and peeling, and can also maintain the hard coat performance of the anti-scattering film. Agent composition can be realized.

It is the cross-sectional schematic by one Embodiment of the adhesive sheet by this invention. It is the cross-sectional schematic by the other embodiment of the adhesive sheet by this invention. It is a section schematic diagram of the hard coat resin film with an adhesive layer by the present invention.

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

The acrylic pressure-sensitive adhesive contained in the pressure-sensitive adhesive composition according to the present invention is cross-linked by reacting with a cross-linking agent to be described later, and comprises a polymer containing (meth) acrylic acid ester as an essential component as a monomer unit. The glass transition temperature is in the range of −20 to 10 ° C. The pressure-sensitive adhesive used in the conventional hard coat resin film with a pressure-sensitive adhesive layer is obtained by crosslinking an acrylic pressure-sensitive adhesive having a glass transition temperature in the range of about −60 ° C. to −20 ° C. with a crosslinking agent. However, when an acrylic pressure-sensitive adhesive having a high glass transition temperature as described above is used, the glass transition temperature of the pressure-sensitive adhesive after crosslinking is also increased. As a result, the storage elastic modulus of the pressure-sensitive adhesive at 25 ° C. can be in the range of 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa, and it has excellent impact resistance and can prevent floating and peeling. In addition, a pressure-sensitive adhesive composition that can maintain the hard coat performance of the scattering prevention film can be realized. However, the storage elastic modulus of the pressure-sensitive adhesive is not determined only by the type of the above-mentioned monomer, but the type of (meth) acrylic acid ester, and the monomers (meth) acrylic acid ester and acrylonitrile It is possible to adjust the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive by the blending ratio of the polymer, the molecular weight of the obtained polymer (or copolymer), and the type and blending amount of the crosslinking agent described later. Needless to say. In this invention, it is preferable that the glass transition temperature of the polymer (acrylic adhesive) which contains (meth) acrylic acid ester as a monomer is -10-10 degreeC.

In the present invention, by using an acrylic pressure-sensitive adhesive having a glass transition temperature in the range of −20 to 10 ° C. as described above, the glass transition temperature of the pressure-sensitive adhesive after crosslinking with a crosslinking agent is 20 to 40. The storage elastic modulus of the pressure-sensitive adhesive can be in the range of 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa. As a result, it is possible to realize a pressure-sensitive adhesive composition that has excellent impact resistance, can prevent floating and peeling, and can maintain the hard coat performance of the anti-scattering film. When the storage elastic modulus is less than 1.0 × 10 ⁷ Pa, the surface hardness of the film is lowered when the pressure-sensitive adhesive layer is provided on the hard coat resin film. On the other hand, when the storage elastic modulus exceeds 2.4 × 10 ⁸ Pa, not only the pressure-sensitive adhesive becomes too hard and the impact resistance is inferior, but also the cohesive force of the pressure-sensitive adhesive is lowered to suppress floating and peeling. become unable. In addition, when the storage elastic modulus is higher than the above range, zipping occurs, and when the hard coat resin film with the pressure-sensitive adhesive layer is bonded to the adherend and then pasted again, the adhesive remains on the adherend. There is. In the present invention, the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive after being crosslinked with a crosslinking agent is more preferably in the range of 1.0 × 10 ^{7 to} 3.2 × 10 ⁷ Pa.

  The glass transition temperature of the polymer obtained by polymerizing the monomer units can be appropriately adjusted by changing the type of monomer units to be used, the ratio of the monomer units to be combined, and the like. As the (meth) acrylic acid ester which is a monomer unit as the main component of the acrylic pressure-sensitive adhesive, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-octyl (meth) 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 the present specification, (meth) acrylic acid refers to acrylic acid and / or methacrylic acid, and (meth) acrylate refers to acrylate and / or methacrylate.

  Some of the (meth) acrylic acid esters described above have a glass transition temperature in the above range even when polymerized alone (homopolymer), but the glass transition temperature of the homopolymer is in the above range. In the present invention, the glass transition temperature of the polymer copolymerized by combining various monomer units may be in the above range. For example, the glass transition temperature of a polymer (homopolymer) obtained by polymerizing n-butyl (meth) acrylate alone is -54 ° C., and the glass transition temperature of a polymer (homopolymer) obtained by polymerizing methyl acrylate alone is 6. ° C. Therefore, the glass transition temperature of the copolymer obtained can be prepared within the range of -54 ° C to 6 ° C by changing the blending ratio of these monomer units. The monomer unit used for adjusting the glass transition temperature is not limited to (meth) acrylic acid. For example, (meth) acrylic such as acrylonitrile which is a monomer unit constituting polyacrylonitrile (glass transition temperature is 101 ° C.). It is good also as a copolymer which used together monomer units other than acid ester. In the present invention, the glass transition temperature of the polymer means a value measured by a method (DMA method) based on the peak top value of loss tangent (tan δ). The loss tangent is determined by the value of loss elastic modulus / storage elastic modulus. These elastic moduli are measured using a dynamic viscoelasticity measuring device for stress when a force is applied to the polymer at a constant frequency.

  The acrylic pressure-sensitive adhesive used in the present invention is a monomer unit of a (meth) acrylic acid ester having a functional group other than the above (meth) acrylic acid ester as long as the glass transition temperature of the polymer used is within the above range. May be used in combination. In the present invention, a hydroxyl group-containing (meth) acrylate monomer and / or a carboxyl group-containing (meth) acrylate monomer may be included as the (meth) acrylic acid ester having a functional group. By adding these hydroxyl group-containing (meth) acrylates and carboxyl group-containing (meth) acrylates as monomers, it is possible to make the pressure-sensitive adhesive having a higher glass transition temperature, and the storage modulus of the pressure-sensitive adhesive at 25 ° C. It becomes easy to adjust.

  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 alcohol and the like. 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.

As described above, the content of the hydroxyl group-containing (meth) acrylate monomer and the carboxyl group-containing (meth) acrylate monomer is such that the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive is 1.0 × 10 ⁷ to 2. It can be appropriately determined in relation to other cross-linking agents and the amount of addition thereof so as to be in the range of 4 × 10 ⁸ Pa. Depending on the type of cross-linking agent and the amount of the cross-linking agent, the hydroxyl value of the acrylic pressure-sensitive adhesive (copolymer) obtained by copolymerizing the above monomers is 0.05 to 5 mgKOH / g. It is preferable to add a hydroxyl group-containing (meth) acrylate monomer, and the carboxyl group-containing (meth) group so that the acrylic adhesive (copolymer) has an acid value of 0.05 to 80 mgKOH / g. It is preferable to blend an acrylate 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 cohesive force of the pressure-sensitive adhesive composition may be inferior. On the other hand, 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.

The copolymer (acrylic pressure-sensitive adhesive) obtained by copolymerizing the monomers as described above has a glass transition temperature in the range of −20 to 10 ° C., and the glass transition temperature of the conventional acrylic pressure-sensitive adhesive. (About −60 to −20 ° C.). The pressure-sensitive adhesive obtained by crosslinking such an acrylic pressure-sensitive adhesive with a cross-linking agent has a glass transition temperature of 20 to 40 ° C. As a result, the storage elastic modulus of the pressure-sensitive adhesive at 25 ° C. is 1.0 × 10 ^{7 to} 2.4. The range can be × 10 ⁸ Pa. In the present invention, a preferable storage elastic modulus range is 1.0 × 10 ^{7 to} 3.2 × 10 ⁷ Pa.

  Next, the crosslinking agent will be described. The pressure-sensitive adhesive composition according to the present invention contains a crosslinking agent as an essential component in addition to the acrylic pressure-sensitive adhesive described above. A conventionally well-known thing can be used as a crosslinking agent, An isocyanate type crosslinking agent and an epoxy-type crosslinking agent can be used. As the isocyanate-based crosslinking agent, conventionally known ones can be used. For example, a polyisocyanate compound, a trimer of a polyisocyanate compound, or an isocyanate group obtained by reacting a polyisocyanate compound with a polyol compound is terminated. And a urethane prepolymer, a trimer of the urethane prepolymer, and the like. Examples of the polyisocyanate compound include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 3 -Methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate and the like. These isocyanate crosslinking agents may be used alone or in combination of two or more.

  Examples of the epoxy-based crosslinking agent include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diester. Examples include polyfunctional epoxy compounds such as glycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutadiene diglycidyl ether. These epoxy-based crosslinking agents may be used alone or in combination of two or more.

As described above, the addition amount of the crosslinking agent is appropriately adjusted so that the storage elastic modulus of the pressure-sensitive adhesive at 25 ° C. is in the range of 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa. That is, since the storage elastic modulus tends to increase as the addition amount of the crosslinking agent is increased, the addition amount of the crosslinking agent can be adjusted according to the type of the acrylic pressure-sensitive adhesive. For example, when an isocyanate-based crosslinking agent is used, the storage elastic modulus at 25 ° C. is 1. in the range of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive. It can be set as the range of 0 * 10 < ⁷ > -2.4 * 10 < ⁸ > Pa. When the addition amount of the isocyanate-based crosslinking agent is less than 0.2 parts by mass, the storage elastic modulus of the pressure-sensitive adhesive at 25 ° C. is less than 1.0 × 10 ^7, and the surface hardness when the hard coat film is bonded is determined. It cannot be maintained. On the other hand, when the addition amount of the isocyanate-based crosslinking agent exceeds 2.0 parts by mass, the viscosity of the pressure-sensitive adhesive composition is rapidly increased to be gelled, the coating property is deteriorated, and the adhesive force is reduced. In some cases, peeling cannot be suppressed.

Moreover, when an epoxy-type crosslinking agent is used as a crosslinking agent, if it is the range of 0.02-2.0 mass parts by solid ratio with respect to 100 mass parts of acrylic adhesives, at 25 degreeC of an adhesive. The storage elastic modulus can be in the range of 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa. When the addition amount of the epoxy-based crosslinking agent is less than 0.02 parts by mass, the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive is less than 1.0 × 10 ^7, and the surface hardness when the hard coat film is bonded is determined. It cannot be maintained. On the other hand, when the addition amount of the epoxy-based crosslinking agent exceeds 2.0 parts by mass, the cohesive force of the pressure-sensitive adhesive may be reduced, and it may not be possible to suppress floating or peeling.

  The above-mentioned cross-linking agent and its addition amount are only one embodiment of the present invention, and other cross-linking agents may be used. For example, known cross-linking agents such as aziridine cross-linking agents and metal chelate cross-linking agents are limited. It can be used without.

  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.

<Adhesive sheet>
As shown in FIG. 1, the pressure-sensitive adhesive sheet according to the present invention comprises a release paper 20 and a pressure-sensitive adhesive layer 10 provided on the release paper 20, and the pressure-sensitive adhesive layer described above is a pressure-sensitive adhesive composition. It consists of In the embodiment shown in FIG. 1, the release paper 20 is provided only on one side of the pressure-sensitive adhesive layer 10. However, as shown in FIG. 2, the first release paper is provided on both sides of the pressure-sensitive adhesive layer 10. An embodiment (not shown) having a layer configuration in which 20A and the second release paper 20B are provided may be used. In the present specification, the first release paper and the second release paper are collectively referred to as release paper.

  The pressure-sensitive adhesive sheet can be provided with a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to a release paper to be described later and drying it. Moreover, when providing release paper on both surfaces of an adhesive layer, after apply | coating an adhesive composition to 1st release paper and making it dry, a 2nd release paper is bonded together to an application surface, and an adhesive sheet is obtained. be able to. Alternatively, the adhesive sheet may be formed by applying the adhesive composition to the first release paper and drying it to form an adhesive layer without bonding the second release paper. In this case, the adhesive of the adhesive sheet The adherend may be bonded to the surface where the layer is exposed (the surface opposite to the side where the first release paper is bonded).

  The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet is preferably about 5 to 20 μm. If the thickness of the pressure-sensitive adhesive layer (the coating amount of the pressure-sensitive adhesive composition) is too thin, there is a possibility that floating or peeling may occur due to a decrease in the adhesive strength. Moreover, since the pressure-sensitive adhesive after crosslinking has the storage elastic modulus as described above, when the surface of the hard coat resin film as the adherend is subjected to decorative printing or the like, the step is adhered. The agent layer cannot absorb and may cause tunneling on mold release. On the other hand, when the thickness exceeds 20 μm, the adhesive strength and the like are improved, but the surface hardness of the adherend when the adherend such as a hard coat resin film is bonded may be lowered. Moreover, when the thickness of the pressure-sensitive adhesive layer becomes too thick, the transparency of the pressure-sensitive adhesive layer is deteriorated and may not be suitable as a display member for a mobile information terminal or the like.

  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. After the adhesive composition is applied to the release surface of the first release paper by the above-described coating method and dried, the second release paper may be bonded.

  The first release paper and the second release paper may be the same or different. As the release paper, conventionally known ones such as a release film, a separate paper, a separate film, a separate paper, a release film, a release paper and the like 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, and 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 / or second release paper is preferably about 10 to 100 mN / 25 cm, more preferably 50 to 80 mN / 25 cm with respect to the pressure-sensitive adhesive sheet. When the release force of the release layer is less than 10 mN / 25 cm, the release force from the pressure-sensitive adhesive sheet or the adherend is weak, and it peels off or partially floats. Moreover, when it exceeds 100 mN / 25 cm, the release force of the release paper is strong and zipping may occur. From the viewpoint of stable releasability and workability, an addition and / or polycondensation type curable silicone resin for release paper, which is mainly composed of polydimethylsiloxane, is preferable as the release paper.

<Hard coat resin film with adhesive layer>
As shown in FIG. 2, the hard coat resin film with an adhesive layer according to the present invention is bonded by bonding the surface of the adhesive layer 10 of the adhesive sheet 1 to one surface of the hard coat resin film 30. The hard coat resin film 30 with the agent layer 10 can be obtained. When using the hard coat resin film 30 with the pressure-sensitive adhesive layer 10, the release paper 20 provided on the other surface of the pressure-sensitive adhesive layer is peeled off to expose the pressure-sensitive adhesive layer 10 and adherend (for example, a glass substrate). By sticking together, the adherend surface can be protected with a hard coat resin film.

  Conventionally known hard coat resin films can be used. For example, an ionizing radiation curable resin composition such as urethane acrylate or polyester acrylate is applied to the surface of a film substrate such as a polyethylene terephthalate film. And what was hardened | cured by ionizing radiation irradiation is mentioned, However, It is not limited to this, A various hard coat resin film can be used.

  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>
Example 1
As an acrylic adhesive, Teisan Resin WS-023 containing acrylonitrile as a monomer unit (solid content 23%, glass transition temperature-10 ° C., mass average molecular weight 500,000, an acrylic copolymer having a carboxyl group and a hydroxyl group as a functional group, 100 parts by mass of Nagase ChemteX Corporation), 0.5 parts by weight of tolylene diisocyanate crosslinking agent (Coronate L45, solid content: 100%, manufactured by Nippon Polyurethane Co., Ltd.) in solid ratio, and diluent for adjusting viscosity As a mixture, ethyl acetate was blended at a ratio of 490 parts by mass and mixed with a stirrer to obtain a pressure-sensitive adhesive composition. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

Example 2
Viscosity adjustment with 100 parts by mass of Teisan Resin WS-023 as an acrylic adhesive and 0.05 parts by mass of an epoxy crosslinking agent (TETRAD-X, solid content: 100%, manufactured by Mitsubishi Gas Chemical Co., Ltd.) As a diluent solvent, ethyl acetate was blended at a ratio of 490 parts by mass and mixed with a stirrer to obtain a pressure-sensitive adhesive composition. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

Example 3
As an acrylic pressure-sensitive adhesive, X-312-134S-6 which does not contain acrylonitrile as a monomer unit (solid content 35%, glass transition temperature -20 ° C., mass average molecular weight 650,000, functionality mainly composed of butyl methacrylate) 100 parts by mass of an acrylic copolymer having a carboxyl group and a hydroxyl group as a group) and 0.25 parts by mass of a xylene diisocyanate-based cross-linking agent (K-341, solid content: 75%, manufactured by Seiden Chemical Co., Ltd.) The pressure-sensitive adhesive composition was obtained by blending 270 parts by mass of ethyl acetate as a dilution solvent for adjusting the viscosity and mixing with a stirrer. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

Example 4
Viscosity adjustment with 100 parts by mass of Teisan Resin WS-023 as an acrylic adhesive and 0.02 parts by mass of an epoxy crosslinking agent (TETRAD-X, solid content: 100%, manufactured by Mitsubishi Gas Chemical Co., Ltd.) As a diluent solvent, ethyl acetate was blended at a ratio of 490 parts by mass and mixed with a stirrer to obtain a pressure-sensitive adhesive composition. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

Comparative Example 1
As an acrylic pressure-sensitive adhesive, Teisan resin SG708-6 containing acrylonitrile as a monomer unit (solid content 20%, glass transition temperature 4 ° C., mass average molecular weight 700,000, an acrylic copolymer having a carboxyl group and a hydroxyl group as a functional group, Nagase 100 parts by mass of Chemtex) and 0.05 parts by mass of epoxy-based cross-linking agent (TETRAD-X, solid content: 100%, manufactured by Mitsubishi Gas Chemical) as a dilution solvent for adjusting viscosity Ethyl acetate was blended at a ratio of 490 parts by mass and mixed with a stirrer to obtain a pressure-sensitive adhesive composition. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

Comparative Example 2
As an acrylic adhesive, SK Dyne 2468 that does not contain acrylonitrile as a monomer unit (solid content 23%, glass transition temperature −40.3 ° C., weight average molecular weight 900,000, acrylic copolymer having butyl acrylate as a main component as a monomer unit) 100 parts by mass of coalescence, manufactured by Soken Chemical Co., Ltd., 5.8 parts by mass of a tolylene diisocyanate crosslinking agent (Coronate L45, solid content: 100%, manufactured by Nippon Polyurethane Co., Ltd.) and a silane coupling agent ( KB-4, solid content: 100%, manufactured by Soken Chemical Co., Ltd.) in a solid ratio of 0.3 part by mass and 400 parts by mass of ethyl acetate as a dilution solvent for viscosity adjustment are mixed with a stirrer. Thus, a pressure-sensitive adhesive composition was obtained. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

Comparative Example 3
Viscosity adjustment with 100 parts by mass of Teisan Resin WS-023 as an acrylic adhesive and 0.2 parts by mass of tolylene diisocyanate crosslinking agent (Coronate L45, solid content: 100%, manufactured by Nippon Polyurethane Co., Ltd.) As a diluent solvent, ethyl acetate was blended at a ratio of 490 parts by mass and mixed with a stirrer to obtain a pressure-sensitive adhesive composition. In addition, the compounding quantity (100 mass part) of an acryl-type copolymer is a compounding quantity also including solvents other than solid content.

<Evaluation of adhesive composition>
38 μm thick PET carrier film (product name POL382150, manufactured by Lintec Co., Ltd.) obtained by subjecting the pressure-sensitive adhesive compositions of Examples and Comparative Examples obtained as described above to a silicone release treatment so that the dried thickness becomes 10 μm. Then, after applying with an applicator and drying at 100 ° C. for 10 minutes, an adhesive layer was formed. A pressure-sensitive adhesive sheet was obtained by laminating a hard coat film having a surface pencil hardness of 3H on the surface of the pressure-sensitive adhesive layer and aging at normal temperature and normal temperature for 1 week. After cutting this out to a size of 25 mm × 70 mm, the PET carrier film was peeled off and bonded to a glass plate using a rubber roller to obtain a hard coat film with an adhesive layer.

  The strength when peeling the pressure-sensitive adhesive layer from the hard coat film with the pressure-sensitive adhesive layer was measured using a tensile tester (type 5565, manufactured by Instron) at room temperature, tensile speed = 300 mm / min, peel angle = 180. The peel strength (N / 25 mm) was measured under the conditions of ° (conforming to JIS Z0237). The evaluation results were as shown in Table 1 below.

  Moreover, the adhesive sheet was heat-treated in an autoclave apparatus under the conditions of 0.5 MPa, 50 ° C., and 30 minutes, and then the carrier films on both sides were peeled to obtain an adhesive. A dynamic viscoelasticity measurement method based on JIS K7244-1 is used to measure the storage elastic modulus E ′ of this pressure-sensitive adhesive at 25 ° C. using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments. (Attachment mode: compression mode, frequency: 1 Hz, temperature: −50 to 150 ° C., heating rate: 5 ° C./min). The results were as shown in Table 1 below.

  Moreover, a carrier film is peeled from the obtained hard coat film with an adhesive layer, it affixes on a glass plate, The pencil hardness (adhesive sheet pencil hardness) of the hard coat surface is measured according to JISK5600-5-4. did. For comparison, a hard coat film having a surface pencil hardness of 3H was fixed on a glass plate, and the pencil hardness of the hard coat surface was measured under the same conditions as described above. The results were as shown in Table 1 below.

Claims (9)

An adhesive composition comprising at least an acrylic adhesive and a crosslinking agent,
The acrylic pressure-sensitive adhesive is a polymer containing (meth) acrylic acid ester as a monomer,
The glass transition temperature of the polymer is in the range of −20 to 10 ° C.,
The pressure-sensitive adhesive composition obtained by crosslinking the acrylic pressure-sensitive adhesive with a crosslinking agent has a storage elastic modulus at 25 ° C. of 1.0 × 10 ^{7 to} 2.4 × 10 ⁸ Pa. Composition.   The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic pressure-sensitive adhesive comprises (meth) acrylic acid ester and acrylonitrile as monomers.   The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic pressure-sensitive adhesive comprises methyl acrylate as a monomer.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the acrylic pressure-sensitive adhesive further comprises a hydroxyl group-containing (meth) acrylate and / or a carboxyl group-containing (meth) acrylate as a monomer. object.   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the crosslinking agent is an isocyanate-based crosslinking agent and is contained in an amount of 0.3 to 3.0% by mass with respect to the acrylic pressure-sensitive adhesive. .   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the crosslinking agent is an epoxy-based crosslinking agent and is contained in an amount of 0.03 to 3.0% by mass with respect to the acrylic pressure-sensitive adhesive. .   The pressure-sensitive adhesive composition according to any one of claims 1 to 6, wherein a glass transition temperature after the acrylic pressure-sensitive adhesive is crosslinked with a crosslinking agent is 20 to 40 ° C.   It is an adhesive sheet provided with the release paper and the adhesive layer provided on the said release paper, Comprising: The said adhesive layer consists of an adhesive composition as described in any one of Claims 1-7. , Adhesive sheet.   A hard coat resin film with an adhesive layer, wherein the adhesive layer of the adhesive sheet according to claim 8 is bonded to a hard coat resin film.

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