CN111100585B - Anti-scattering adhesive sheet - Google Patents

Abstract

The invention provides a scattering prevention adhesive sheet with high durability under a damp and hot environment. The scattering prevention adhesive sheet (1) comprises a substrate (11) and an adhesive layer (12) provided on at least one surface side of the substrate (11), wherein the adhesive constituting the adhesive layer (12) contains a polymer and also a carbodiimide, the gel fraction of the adhesive is 10% or more, and the acid value of the polymer is 50mgKOH/g or less.

Description

Anti-scattering adhesive sheet

Technical Field

The present invention relates to a scattering prevention adhesive sheet to be attached to an adherend so as not to scatter the adherend after breakage.

Background

In recent years, a car navigation system is generally mounted in a car. In a display body (display) of a car navigation system, a protective panel is generally provided on a surface side of a liquid crystal module. In many cases, a scattering prevention film composed of a base film and an adhesive layer is attached to the protective panel from the viewpoint of safety such that the broken protective panel is not scattered in an accident or the like.

On the other hand, when a driver of an automobile sometimes wears polarizing sunglasses and the angle of the polarizing axis of the polarizing sunglasses coincides with the angle of the polarizing axis of the liquid crystal module, the driver sometimes cannot see the display of the display at all (blackout). In order to prevent such blackout, a cellulose acetate film which is an isotropic film is sometimes used as a base material film of the above-described scattering prevention film.

Patent document 1 proposes a scattering prevention film for an image display device, which is characterized by comprising a base film formed of a cellulose triacetate film having a refractive index of 1.45 to 1.55 and an adhesive layer having a refractive index of 1.45 to 1.55 provided on at least one surface of the base film.

Patent document 2 proposes a touch panel-equipped liquid crystal display device including a touch panel module and a liquid crystal display panel, wherein the touch panel module includes a glass substrate on the outermost surface, a pair of transparent conductive films formed in a lattice shape in an X direction and a Y direction orthogonal thereto, and a glass shatter prevention film on the upper surface thereof, and the direction of the maximum elastic modulus of the glass shatter prevention film is a direction inclined with respect to the X direction or the Y direction of the pair of transparent conductive films formed in the lattice shape, and patent document 2 also proposes the use of a cellulose ester film as the glass shatter prevention film.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2011-209512

Patent document 2: japanese patent No. 5831559

Disclosure of Invention

Technical problem to be solved by the invention

However, cellulose acetate films have a technical problem that they are easily hydrolyzed and deteriorated in a moist heat environment. Particularly, since the contents of the automobile are easily changed to high temperature and high humidity, the above technical problems are severe. On the other hand, patent documents 1 and 2 do not disclose the technical problem at all. When the adhesive of the anti-scattering film for an image display device disclosed in patent document 1 is studied, the effect of suppressing the progress of hydrolysis of the cellulose acetate film in a moist heat environment is not necessarily sufficient. Further, the details of the adhesive are not disclosed in patent document 2.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a scattering prevention adhesive sheet having high durability in a hot and humid environment.

Means for solving the problems

In order to achieve the above object, the first aspect of the present invention provides a scattering prevention adhesive sheet comprising a base material and an adhesive layer provided on at least one surface side of the base material, wherein the adhesive constituting the adhesive layer contains a polymer and a carbodiimide, the adhesive has a gel fraction of 10% or more, and the polymer has an acid value of 50mgKOH/g or less (invention 1).

The scattering prevention adhesive sheet of the invention (invention 1) can suppress deterioration such as cracking of a substrate (hydrolyzable substrate) even when the substrate is usually hydrolyzed when exposed to a moist heat environment. In addition, the peeling of the interface between the substrate and the adhesive layer is suppressed. That is, the scattering prevention adhesive sheet of the invention (invention 1) has high durability under a hot and humid environment. The scattering prevention adhesive sheet of the present invention can also be used as an adhesive sheet not intended for scattering prevention.

In the above invention (invention 1), it is preferable that the polymer is crosslinked by an isocyanate-based crosslinking agent (invention 2).

In the above inventions (inventions 1 and 2), the polymer preferably has a hydroxyl value of 1mgKOH/g or more and 300mgKOH/g or less (invention 3).

In the above inventions (inventions 1 to 3), the polymer is preferably a (meth) acrylate polymer (invention 4).

In the above inventions (inventions 1 to 4), the content of carbodiimide in the adhesive is preferably 0.01 mass% to 10 mass% (invention 5).

In the above inventions (inventions 1 to 5), the substrate is preferably a hydrolyzable substrate (invention 6).

Effects of the invention

The scattering prevention adhesive sheet of the present invention has high durability in a hot and humid environment.

Drawings

Fig. 1 is a sectional view of an anti-scattering adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a sectional view showing one configuration example of the display device.

Fig. 3 is a sectional view showing another configuration example of the display device.

Fig. 4 is a sectional view showing a configuration example of the vehicle instrument panel.

Description of the reference numerals

1: a scattering prevention adhesive sheet; 11: a water-decomposable substrate (an example of a substrate); 12: an adhesive layer; 13: peeling off the sheet; 2: a protective panel; 3: a transparent conductive film; 4: an adhesive layer; 5: a membrane sensor; 51: a substrate film; 52: a transparent conductive film; 6: an adhesive layer; 7: a display body module; 10A, 10B: a display device; 8: an instrument panel for a vehicle; 81: a display device for an instrument panel; 82: a cover body (cover).

Detailed Description

Hereinafter, embodiments of the present invention will be described.

The scattering prevention adhesive sheet according to one embodiment of the present invention is an adhesive sheet including a base material and an adhesive layer provided on at least one surface side of the base material, and preferably the adhesive sheet is formed by laminating a release sheet on a surface of the adhesive layer opposite to the base material.

The substrate is not particularly limited, and a substrate (various plastic films) generally used as a substrate of the scattering prevention adhesive sheet can be used. However, in the present embodiment, it is preferable to use a hydrolyzable substrate that directly exhibits the effect of moisture-heat durability by the adhesive layer.

Fig. 1 shows a specific configuration of an example of the scattering prevention adhesive sheet of the present embodiment. In this specific structure, the hydrolyzable base material 11 is used as an example of the base material, but the present invention is not limited thereto.

As shown in fig. 1, the scattering prevention adhesive sheet 1 of the present embodiment is formed by laminating a hydrolyzable substrate 11, an adhesive layer 12, and a release sheet 13 in this order. The release sheet 13 is laminated such that its release surface is in contact with the adhesive layer 12. The release surface of the release sheet in the present specification means a surface having releasability in the release sheet, and includes any of a surface subjected to a release treatment and a surface which has not been subjected to a release treatment but exhibits releasability.

1. Each component

1-1. Hydrolyzable substrate

The hydrolyzable substrate in the present embodiment means a substrate that is easily hydrolyzed in a moist heat environment, for example, an environment of 85 ℃ and 85% rh. Examples of the hydrolyzable substrate 11 of the present embodiment include a cellulose acetate film, a biodegradable plastic film such as polylactic acid (PLA), and a laminate film having these films. Examples of the cellulose acetate film include a cellulose triacetate film and a cellulose diacetate film.

When the hydrolyzable substrate 11 is a laminate film having a cellulose acetate film, it is preferable that at least a portion of the hydrolyzable substrate 11 which is in contact with the adhesive agent layer 12 is a cellulose acetate film. With this structure, the effect of improving the moisture and heat durability by the adhesive layer 12 can be more easily exhibited.

The thickness of the hydrolyzable substrate 11 is preferably 10 μm or more, particularly preferably 20 μm or more, and more preferably 30 μm or more. The thickness of the hydrolyzable substrate is preferably 300 μm or less, particularly preferably 200 μm or less, and more preferably 100 μm or less. When the thickness of the hydrolyzable substrate 11 is within the above range, the optical properties of the adherend are not impaired, and when the adherend is a member (for example, a glass plate, a plastic plate, or the like) which is easily broken by an impact or the like, a scattering prevention effect of preventing scattering of the adherend after the breakage can be exhibited.

1-2. Adhesive layer

The adhesive constituting the adhesive layer 12 in the present embodiment contains a polymer and at the same time a carbodiimide. The adhesive has a gel fraction of 10% or more, and the polymer has an acid value of 50mgKOH/g or less. Thus, even when the water-disintegrable substrate 11 is usually hydrolyzed when the scattering prevention adhesive sheet 1 of the present embodiment is placed in a hot and humid environment, deterioration such as cracking of the water-disintegrable substrate 11 can be suppressed. In addition, the peeling at the interface between the hydrolyzable substrate 11 and the adhesive layer 12 is also suppressed.

In the present embodiment, the carbodiimide functions as a hydrolysis inhibitor that traps active hydrogen generated by hydrolysis and inhibits the hydrolysis. Further, since the acid value of the polymer is low as described above, hydrolysis of the hydrolyzable substrate 11 is not promoted by the adhesive layer 12. Further, since the gel fraction of the adhesive is as high as a certain degree as described above, the cohesive force of the adhesive is increased, and thus the durability of the adhesive layer 12 itself is improved, and the peeling from the hydrolyzable substrate 11 can be more effectively suppressed. Thus, the scattering prevention adhesive sheet 1 of the present embodiment has high durability in a hot and humid environment.

The carbodiimide of the present embodiment has a carbodiimide group (-N = C = N-), and may be present independently as a carbodiimide compound in the adhesive or may be present by bonding to the polymer. The adhesive may be mixed with both of them. When carbodiimide is present in a state bonded to the polymer, for example, carbodiimide compounds having a reactive functional group (for example, isocyanate group) at the end thereof are present as a substance (optionally, crosslinked substance) in which carbodiimide compounds react with and are bonded to a polymer having a reactive functional group (for example, hydroxyl group).

The carbodiimide compound may have at least one carbodiimide group, and may have 2 or more carbodiimide groups. That is, the carbodiimide compound may be a monocarbodiimide compound (a compound having one carbodiimide group) or may be a polycarbodiimide compound (a compound having 2 or more carbodiimide groups). Further, in the carbodiimide compound, a carbodiimide group may be bonded to a hydrocarbon group or a hydrocarbon skeleton. One carbodiimide compound may be used alone, or two or more carbodiimide compounds may be used in combination.

In the present embodiment, a polycarbodiimide compound is preferably used from the viewpoint of durability under a hot and humid environment.

Preferable examples of the monocarbodiimide compound include an aliphatic monocarbodiimide compound, an alicyclic monocarbodiimide compound, and an aromatic monocarbodiimide compound.

Examples of the aliphatic monocarbodiimide compound include dialkylcarbodiimide compounds such as 1,3-dimethylcarbodiimide, 1,3-diisopropylcarbodiimide, 1-isopropyl-3-tert-butylcarbodiimide, 1,3-dihexylcarbodiimide, 1,3-dioctylcarbodiimide, 1-isopropyl-3-dodecylcarbodiimide, 1,3-dioctyldecylcarbodiimide and 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide.

Examples of the alicyclic monocarbodiimide compound include dicycloalkylcarbodiimide compounds such as 1,3-dicyclohexylcarbodiimide.

Examples of the aromatic monocarbodiimide compound include a diarylcarbodiimide compound, an arylcycloalkylcarbodiimide compound, and an alkylarylcarbodiimide compound. Examples of the diarylcarbodiimide compound include N, N ' -diphenylcarbodiimide, N ' -di-o-tolylcarbodiimide, N ' -bis (2,6-dimethylphenyl) carbodiimide, N, N ' -bis (2,4,6-trimethylphenyl) carbodiimide, N ' -bis (2,6-diethylphenyl) carbodiimide, N ' -bis (2-ethyl-6-isopropylphenyl) carbodiimide, N ' -bis (2,6-diisopropylphenyl) carbodiimide, N, N ' -bis (2,4,6-triisopropylphenyl) carbodiimide, N ' -bis (2-isobutyl-6-isopropylphenyl) carbodiimide, N ' -bis (2,6-di-tert-butylphenyl) carbodiimide, N-phenyl-N ' -tolylcarbodiimide, N, N ' -di- β -naphthylcarbodiimide, N ' -di (p-nitrophenyl) carbodiimide, N ' -di (p-aminophenyl) carbodiimide, N ' -di (p-hydroxyphenyl) carbodiimide, and the like. Examples of the arylcycloalkylcarbodiimide compound include N-tolyl-N' -cyclohexylcarbodiimide and the like. Examples of the alkyl aralkyl carbodiimide compound include benzyl isopropyl carbodiimide and the like.

Polycarbodiimide compounds can be produced mainly by a condensation reaction accompanied by decarbonation of an organic diisocyanate. Examples of the organic diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4 '-diphenylmethane diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, 4,4' -biphenylene diisocyanate, 3,3 '-dimethoxy-4,4' -biphenyl diisocyanate, 3,3 '-dimethyl-4,4' -biphenyl diisocyanate, 3,3 '-dimethyl diphenylmethane-4,4' -diisocyanate, xylylene diisocyanate, hexamethylene-1,6-diisocyanate, lysine diisocyanate, hydrogenated methylene diphenyl diisocyanate, isophorone diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more.

Examples of the polycarbodiimide compound include aliphatic polycarbodiimide compounds, alicyclic polycarbodiimide compounds, and aromatic polycarbodiimide compounds. Examples of the aliphatic polycarbodiimide compound include polyalkylene carbodiimides such as polyhexamethylene carbodiimide. Examples of the alicyclic polycarbodiimide compound include polydicycloalkylalkanecarbodiimides such as poly (4,4' -dicyclohexylmethanecarbodiimide). Examples of the aromatic polycarbodiimide compound include a polyarylene carbodiimide, a polydiarylalkane carbodiimide, and the like. Examples of the polyarylene carbodiimide include poly (m-phenylene carbodiimide), poly (p-phenylene carbodiimide), poly (toluene carbodiimide), poly (diisopropylphenylene carbodiimide), and poly (methyl diisopropylphenylene carbodiimide). Further, as the polydiarylalkane carbodiimide, for example, poly (4,4' -diphenylmethane carbodiimide) and the like can be mentioned.

The number average molecular weight (Mn) of the polycarbodiimide compound is preferably 200 or more, and preferably 50000 or less.

The number average molecular weight (Mn) in the present specification is a value in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

The terminal group of the polycarbodiimide compound is not particularly limited, and may be a group derived from a raw material such as an isocyanate group, or may be a group in which a part or all of the terminal is blocked or protected. For example, the terminal isocyanate group may be a group blocked with a blocking agent such as an amine, an alcohol, or a monoisocyanate.

As described above, the polycarbodiimide compound is mainly prepared by a condensation reaction accompanied by decarbonation of an organic diisocyanate, and thus the terminal group is sometimes an isocyanate group.

When the polycarbodiimide compound has a terminal isocyanate group, the proportion of the isocyanate group to the whole polycarbodiimide compound is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and further preferably 0.5% by mass or more. The proportion of the isocyanate group is preferably 30% by mass or less, more preferably 20% by mass or less, particularly preferably 15% by mass or less, and further preferably 10% by mass or less.

The lower limit of the content of the carbodiimide in the adhesive constituting the adhesive layer 12 is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.4% by mass or more, and further preferably 0.9% by mass or more. When the lower limit of the carbodiimide content is set as described above, the moist heat durability of the scattering prevention adhesive sheet 1 can be more effectively improved.

The upper limit of the content of carbodiimide in the adhesive constituting the adhesive layer 12 is preferably 10 mass% or less, particularly preferably 5 mass% or less, and more preferably 3 mass% or less. When the upper limit of the carbodiimide content is set as described above, precipitation from the adhesive is suppressed, and more favorable adhesion can be exhibited.

In particular, the gel fraction of the adhesive is preferably 10% or more, more preferably 20% or more, particularly preferably 35% or more, and even more preferably 50% or more, from the viewpoint of suppressing the peeling of the adhesive layer 12 and the hydrolyzable substrate 11. The gel fraction of the adhesive is preferably 95% or less, more preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less. This prevents the adhesive from becoming too hard, and exhibits good adhesive force and excellent adhesion to an adherend. Here, the method of measuring the gel fraction of the adhesive is shown in the test examples described later.

From the viewpoint of suppressing hydrolysis of the hydrolyzable substrate 11, the acid value of the polymer is preferably 50mgKOH/g or less, more preferably 30mgKOH/g or less, particularly preferably 20mgKOH/g or less, and still more preferably 10mgKOH/g or less. The lower limit of the acid value of the polymer is preferably as small as possible, and therefore 0mgKOH/g is particularly preferable.

The hydroxyl value of the polymer is preferably 1mgKOH/g or more, more preferably 3mgKOH/g or more, particularly preferably 5mgKOH/g or more, and still more preferably 9mgKOH/g or more. On the other hand, the hydroxyl value of the polymer is preferably 300mgKOH/g or less, more preferably 200mgKOH/g or less, particularly preferably 100mgKOH/g or less, and still more preferably 50mgKOH/g or less. When the hydroxyl value of the polymer is in the above range, the crosslinking point of the polymer can be appropriately secured, and the adhesive can have a predetermined cohesive force. As a result, the moisture and heat durability is further improved.

Here, the acid value and the hydroxyl value in the present specification are basically theoretical values derived from the blending ratio of the monomers constituting the polymer, and when the theoretical values cannot be derived, they are values measured in accordance with JIS K0070.

The kind of the polymer, that is, the kind of the adhesive constituting the adhesive layer 12 is not particularly limited as long as the adhesive exhibits a desired adhesive force to the hydrolyzable substrate 11 and the adherend and can exert the above-described effects.

The adhesive constituting the adhesive layer 12 may be any of, for example, an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, and a silicone adhesive. The adhesive may be any of emulsion type, solvent type, and non-solvent type, and may be any of crosslinking type and non-crosslinking type. Among them, preferred are acrylic adhesives which easily satisfy the above physical properties and are excellent in adhesive physical properties, optical properties, and the like.

The acrylic pressure-sensitive adhesive may be an active energy ray-curable acrylic pressure-sensitive adhesive, a non-active energy ray-curable acrylic pressure-sensitive adhesive, a thermally crosslinkable acrylic pressure-sensitive adhesive, a non-crosslinkable acrylic pressure-sensitive adhesive, or a combination thereof. Among them, an acrylic adhesive curable with actinic energy rays is preferable from the viewpoint of stability of the curing reaction. The acrylic pressure-sensitive adhesive curable with actinic energy rays is particularly preferably crosslinked, and more preferably thermally crosslinked.

When the type of the adhesive constituting the adhesive layer 12 is an acrylic adhesive, the polymer contained in the adhesive is preferably a (meth) acrylate polymer or a crosslinked product thereof (including a crosslinked product containing carbodiimide). In this case, the adhesive layer 12 is preferably formed of an acrylic adhesive obtained from an adhesive composition containing a (meth) acrylate polymer.

Specifically, the adhesive constituting the adhesive layer 12 is preferably obtained from an adhesive composition containing a (meth) acrylate polymer (a) and a carbodiimide compound (B) (hereinafter, sometimes referred to as "adhesive composition P"). The adhesive composition P preferably further contains a crosslinking agent (C), and in this case, the adhesive is obtained by crosslinking the adhesive composition P. In the present specification, the term (meth) acrylate refers to both acrylate and methacrylate. Other similar terms are also the same. Further, the term "copolymer" is also included in the term "polymer".

(1) Each component

(1-1) (meth) acrylate ester Polymer (A)

When the (meth) acrylate polymer (a) contains an alkyl (meth) acrylate having an alkyl group and 1 to 20 carbon atoms as a monomer unit constituting the polymer, preferable tackiness can be exhibited. From this viewpoint, the (meth) acrylic acid ester polymer (a) preferably contains, as a monomer unit constituting the polymer, at the lower limit, at least 50 mass%, more preferably at least 60 mass%, particularly preferably at least 70 mass%, even more preferably at least 80 mass%, and most preferably at least 90 mass% of an alkyl (meth) acrylate having 1 to 20 carbon atoms containing an alkyl group. When the lower limit of the alkyl (meth) acrylate is as described above, the (meth) acrylate polymer (a) can exhibit appropriate tackiness. The (meth) acrylic acid ester polymer (a) preferably contains 99% by mass or less, particularly preferably 98% by mass or less, and further preferably 97% by mass or less of the alkyl (meth) acrylate as a monomer unit constituting the polymer, in terms of the upper limit value. When the upper limit of the alkyl (meth) acrylate is set to the above range, other monomer components can be introduced into the (meth) acrylate polymer (a) in an appropriate amount.

Examples of the alkyl (meth) acrylate in which the alkyl group has 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl (meth) acrylate, and among them, from the viewpoint of further improving the adhesiveness, a (meth) acrylate in which the alkyl group has 1 to 8 carbon atoms is preferable. These may be used alone or in combination of two or more. The alkyl group in the alkyl (meth) acrylate in which the alkyl group has 1 to 20 carbon atoms is a linear, branched or cyclic alkyl group.

Further, as the alkyl (meth) acrylate in which the alkyl group has 1 to 20 carbon atoms, it is preferable to use a hard monomer having a glass transition temperature (Tg) of more than 0 ℃ (preferably 70 ℃ or higher) as a homopolymer in combination with a soft monomer having a glass transition temperature (Tg) of 0 ℃ or lower (preferably-40 ℃ or lower) as a homopolymer. This is because the adhesion can be made higher by securing flexibility with the soft monomer and increasing cohesive force with the hard monomer. In this case, the mass ratio of the hard monomer to the soft monomer is preferably 5 to 40, and particularly preferably 15.

Examples of the hard monomer include methyl acrylate (Tg 10 ℃ C.), methyl methacrylate (Tg 105 ℃ C.), isobornyl acrylate (Tg 94 ℃ C.), isobornyl methacrylate (Tg 180 ℃ C.), adamantyl acrylate (Tg 115 ℃ C.), and adamantyl methacrylate (Tg 141 ℃ C.), and the like. These may be used alone or in combination of two or more.

Among the above hard monomers, methyl acrylate, methyl methacrylate and isobornyl acrylate are preferable from the viewpoint of preventing adverse effects on other properties such as tackiness and transparency and further exhibiting the performance of the hard monomers. In view of the tackiness, methyl acrylate and methyl methacrylate are more preferable, and methyl methacrylate is particularly preferable.

The soft monomer is preferably an alkyl acrylate 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.) and the like are preferable. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (a) preferably contains a reactive functional group-containing monomer as a monomer unit constituting the polymer. The reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (C) described later, whereby a crosslinked structure (three-dimensional network structure) can be formed, and an adhesive having a desired cohesive force can be obtained.

Examples of the reactive functional group-containing monomer contained in the (meth) acrylate polymer (a) as a monomer unit constituting the polymer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer which has excellent reactivity with the crosslinking agent (C) and has little adverse effect on the hydrolyzable substrate 11 is particularly preferable.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is preferable from the viewpoint of reactivity of the hydroxyl group in the obtained (meth) acrylate polymer (a) with the crosslinking agent (C) and copolymerizability of the hydroxyl group with other monomers. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (a) preferably contains 0.5% by mass or more, particularly preferably 1% by mass or more, and further preferably 2% by mass or more of a hydroxyl group-containing monomer as a monomer unit constituting the polymer. The (meth) acrylate polymer (a) preferably contains 40% by mass or less, more preferably 20% by mass or less, particularly preferably 15% by mass or less, and further preferably 10% by mass or less of a hydroxyl group-containing monomer as a monomer unit constituting the polymer. When the (meth) acrylate polymer (a) contains a hydroxyl group-containing monomer as a monomer unit in the above amount, the hydroxyl value of the polymer falls within the above preferred range, a tacky adhesive having a desired cohesive force can be obtained, and the moist heat durability becomes further excellent.

The (meth) acrylate polymer (a) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. This is because, if a carboxyl group as an acid component is present in the adhesive, hydrolysis of the hydrolyzable substrate 11 is promoted.

Here, "not containing a carboxyl group-containing monomer" means that the carboxyl group-containing monomer is not substantially contained, and the carboxyl group-containing monomer is allowed to be contained to such an extent that hydrolysis of the hydrolyzable substrate 11 is not promoted, except that the carboxyl group-containing monomer is not contained at all. Specifically, it is permissible to contain the carboxyl group-containing monomer as a monomer unit in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less in the (meth) acrylate polymer (a).

On the other hand, when the (meth) acrylate polymer (a) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the content thereof is preferably 4% by mass or less, particularly preferably 2% by mass or less, and further preferably 1% by mass or less. Among these, 0 mass% is most preferable. Thus, the acid value of the polymer falls within the above-described preferred range, and the acceleration of hydrolysis of the hydrolyzable substrate 11 can be suppressed to some extent.

The (meth) acrylate polymer (a) preferably further contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. The inclusion of the nitrogen atom-containing monomer can improve the adhesion to an adherend such as glass. Examples of the nitrogen atom-containing monomer include a monomer having an amino group, a monomer having an amide group, and a monomer having a nitrogen-containing heterocycle, and among them, a monomer having a nitrogen-containing heterocycle is preferable. In addition, from the viewpoint of enhancing the degree of freedom of the moiety derived from the nitrogen atom-containing monomer in the high-dimensional structure of the adhesive agent, it is preferable that the nitrogen atom-containing monomer does not contain a reactive unsaturated double bond group other than one polymerizable group used in the polymerization for forming the (meth) acrylate polymer (a).

Examples of the monomer having a nitrogen-containing heterocycle include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, and the like, and among them, N- (meth) acryloylmorpholine which exhibits more excellent adhesion is preferable, and N-acryloylmorpholine is particularly preferable.

Examples of the nitrogen atom-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, N-vinylcaprolactam, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate.

The nitrogen atom-containing monomers mentioned above may be used singly or in combination of two or more.

When the (meth) acrylate polymer (a) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the content thereof is preferably 1% by mass or more, particularly preferably 3% by mass or more, and further preferably 5% by mass or more, from the viewpoint of improving the adhesion to an adherend such as glass. From the viewpoint of ensuring the blending amount of other components, the content is preferably 20% by mass or less, particularly preferably 15% by mass or less, and further preferably 10% by mass or less.

The (meth) acrylate polymer (a) may also contain other monomers as monomer units constituting the polymer, as required. The other monomer is preferably a monomer not containing a reactive functional group so as not to interfere with the action of the reactive functional group-containing monomer. Examples of the other monomer include alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (a) is preferably a solution polymer obtained by a solution polymerization method. By using a solution polymer, a polymer having a high molecular weight can be easily obtained, and an adhesive having more excellent moist heat durability can be obtained.

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

The weight average molecular weight of the (meth) acrylate polymer (a) is preferably 20 ten thousand or more, more preferably 40 ten thousand or more, particularly preferably 60 ten thousand or more, further preferably 80 ten thousand or more, and most preferably 110 ten thousand or more. The weight average molecular weight of the (meth) acrylate polymer (a) is preferably 300 ten thousand or less, more preferably 200 ten thousand or less, particularly preferably 180 ten thousand or less, and further preferably 150 ten thousand or less. When the weight average molecular weight of the (meth) acrylate polymer (a) is within the above range, the obtained adhesive is more excellent in moisture and heat durability. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

In the adhesive composition P, one (meth) acrylate polymer (a) may be used alone, or two or more may be used in combination.

(1-2) carbodiimide Compound (B)

The carbodiimide compound (B) is preferably as described above. The content of the carbodiimide compound (B) is the same as the content of the carbodiimide in the adhesive. The content of the adhesive in the adhesive layer 12 and the content of the adhesive composition P can be regarded as the same.

Here, when the carbodiimide compound (B) containing a carbodiimide compound having a terminal isocyanate group is used, the carbodiimide compound having a terminal isocyanate group may react with a hydroxyl group or the like of the (meth) acrylate polymer (a) by heating the adhesive composition P, thereby bonding to the (meth) acrylate polymer (a) or crosslinking the (meth) acrylate polymer (a).

(1-3) crosslinking agent (C)

The crosslinking agent (C) can crosslink the (meth) acrylate polymer (a) by heating the adhesive composition P, thereby favorably forming a crosslinked structure having a three-dimensional network structure. This provides an adhesive having a predetermined cohesive force, and further has excellent moist heat durability.

The crosslinking agent (C) may be reacted with a reactive functional group of the (meth) acrylate polymer (a), and examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. Here, when the (meth) acrylate polymer (a) contains a hydroxyl group-containing monomer as a structural monomer unit, an isocyanate-based crosslinking agent excellent in reactivity with a hydroxyl group is preferably used as the crosslinking agent (C). The crosslinking agent (C) may be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret forms and isocyanurate forms thereof, and adducts thereof with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil. Among them, trimethylolpropane-modified aromatic polyisocyanates are preferable from the viewpoint of reactivity with hydroxyl groups, and trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are particularly preferable.

The content of the crosslinking agent (C) in the adhesive composition P is preferably 0.01 part by mass or more, particularly preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more, per 100 parts by mass of the (meth) acrylate copolymer (a). The content is preferably 1.0 part by mass or less, particularly preferably 0.8 part by mass or less, and further preferably 0.5 part by mass or less. When the content of the crosslinking agent (C) is within the above range, a predetermined crosslinked structure can be formed, and the obtained adhesive is more excellent in moist heat durability.

(1-4) various additives

Various additives generally used in acrylic adhesives may be added to the adhesive composition P as needed, for example, a silane coupling agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a filler, a refractive index adjuster, and the like may be added. The polymerization solvent or the dilution solvent described later is not included in the additive constituting the adhesive composition P.

Here, when the adhesive composition P contains a silane coupling agent, the adhesion between the obtained adhesive and the glass member or the plastic plate is improved. This provides the adhesive with more excellent moist heat durability.

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

Examples of the silane coupling agent include silicon compounds containing a polymerizable unsaturated group such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, etc.; amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or a condensate of at least one of these with an alkyl-containing silicon compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. These may be used alone or in combination of two or more.

When the adhesive composition P contains a silane coupling agent, the content thereof is preferably 0.01 part by mass or more, particularly preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more, based on 100 parts by mass of the (meth) acrylate polymer (a). The content is preferably 2 parts by mass or less, particularly preferably 1 part by mass or less, and more preferably 0.5 part by mass or less.

(2) Preparation of adhesive composition

The adhesive composition P can be prepared by: the (meth) acrylate polymer (a) is prepared, and the resulting (meth) acrylate polymer (a), carbodiimide compound (B) and crosslinking agent (C) are mixed, and at the same time, additives are added as needed.

The (meth) acrylate polymer (a) can be produced by polymerizing a mixture of monomers constituting the polymer by a general radical polymerization method. The polymerization of the (meth) acrylate polymer (a) is preferably carried out by a solution polymerization method using a polymerization initiator as needed. However, the present invention is not limited thereto, and polymerization may be carried out without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used simultaneously.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used simultaneously. Examples of the azo compounds include 2,2' -azobisisobutyronitrile, 2,2' -azobis (2-methylbutyronitrile), 1,1' -azobis (cyclohexane-1-carbonitrile), 2,2' -azobis (2,4-dimethylvaleronitrile), 2,2' -azobis- (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2 ' -azobis (2-methylpropionate), 4,4' -azobis (4-cyanopentanoic acid), 2,2' -azobis (2-hydroxymethylpropionitrile), and 2,2' -azobis [2- (2-imidazolin-2-yl) propane ].

Examples of the organic peroxide include benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxy) ethyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, peroxy (3,5,5-trimethylhexanoyl), dipropyl peroxide, and diacetyl peroxide.

In the polymerization step, a chain transfer agent such as 2-mercaptoethanol is added to adjust the weight average molecular weight of the obtained polymer.

After the (meth) acrylate polymer (a) is obtained, the carbodiimide compound (B), the crosslinking agent (C), and if necessary, a diluting solvent and additives are added to a solution of the (meth) acrylate polymer (a) and sufficiently mixed to obtain a solvent-diluted adhesive composition P (coating solution). In addition, when a solid substance is used for any of the above components or when the solid substance is precipitated when the solid substance is mixed with another component in an undiluted state, the component may be dissolved or diluted in a diluting solvent in advance and then mixed with another component.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane, cyclohexane, etc.; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and vinyl chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve.

The "viscosity" of the concentration of the coating solution prepared in this manner is not particularly limited as long as it is within a coatable range, and may be appropriately selected depending on the situation. For example, the adhesive composition P is diluted so that the concentration thereof becomes 10 to 60 mass%. In addition, when obtaining the coating solution, the addition of a diluting solvent or the like is not an essential condition, and if the adhesive composition P has a coatable viscosity or the like, the addition of a diluting solvent may not be necessary. In this case, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth) acrylate polymer (a) is directly used as a dilution solvent.

(3) Formation of adhesive layer

The adhesive composition P (coating solution) is preferably applied to a desired object and crosslinked to form the adhesive layer 12. The crosslinking of the adhesive composition P can generally be carried out by heat treatment. Further, the drying treatment when evaporating the diluting solvent or the like from the coating film of the adhesive composition P applied to the desired object may be used as the heating treatment.

The heating temperature of the heating treatment is preferably 50 to 150 ℃, particularly preferably 70 to 120 ℃. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

If necessary, the heat treatment may be followed by a maturation period of about 1 to 2 weeks at room temperature (e.g., 23 ℃ C., 50% RH). When the curing period is required, an adhesive is formed after the curing period, and when the curing period is not required, an adhesive (adhesive layer 12) is formed directly after the heat treatment is completed.

By the above-mentioned heat treatment (and curing), the (meth) acrylate polymer (a) is sufficiently crosslinked via the crosslinking agent (C).

(4) Thickness of adhesive layer

The lower limit of the thickness (value measured according to JIS K7130) of the adhesive layer 12 is preferably 5 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more. When the lower limit of the thickness of the adhesive layer 12 is set as described above, a desired adhesive force can be easily exhibited, and the hydrolysis suppressing effect of the adhesive layer 12 can be sufficiently exhibited.

The upper limit of the thickness of the adhesive layer 12 is preferably 500 μm or less, particularly preferably 200 μm or less, and more preferably 100 μm or less. When the upper limit of the thickness of the adhesive layer 12 is as described above, appearance defects such as indentations and scratches of the adhesive layer can be suppressed. The adhesive layer 12 may be formed of a single layer or a plurality of layers.

1-3. Release sheet

The release sheet 13 protects the adhesive layer 12 until the time of using the scattering prevention adhesive sheet 1, and is released when using the scattering prevention adhesive sheet 1 (adhesive layer 12). In the scattering prevention adhesive sheet 1 of the present embodiment, the release sheet 13 is not necessarily required.

As the release sheet 13, 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, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, an ethylene- (meth) acrylic acid copolymer film, an ethylene- (meth) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or the like can also be used. In addition, crosslinked films thereof may also be used. Further, a laminated film thereof may be used.

The release surface of the release sheet 13 (particularly, the surface in contact with the adhesive layer 12) is preferably subjected to a release treatment. Examples of the release agent used for the release treatment include alkyd based, silicone based, fluorine based, unsaturated polyester based, polyolefin based, and wax based release agents.

The thickness of the release sheet 13 is not particularly limited, but is usually about 20 to 150 μm.

2. Physical Properties

(1) Total light transmittance

The total light transmittance of the adhesive layer 12 of the scattering prevention adhesive sheet 1 of the present embodiment is preferably 80% or more, particularly preferably 90% or more, and more preferably 99% or more. When the total light transmittance of the adhesive layer 12 is as described above, the transparency is extremely high, and the adhesive layer is particularly suitable for optical applications. In addition, the total light transmittance in the present specification is a value measured according to jis k7361-1 1997.

(2) Adhesive force

The lower limit of the adhesive force of the scattering prevention adhesive sheet 1 of the present embodiment to soda lime glass is preferably 5N/25mm or more, particularly preferably 8N/25mm or more, and more preferably 10N/25mm or more. When the lower limit of the adhesive force is as described above, the wet heat durability is further excellent. The upper limit of the above-mentioned adhesive force is preferably 50N/25mm or less, more preferably 45N/25mm or less, and particularly preferably 40N/25mm or less. If the upper limit value of the adhesive force is as described above, good reworkability can be obtained, and re-sticking can be performed even when a sticking error occurs.

Here, the adhesive force in the present specification means an adhesive force measured basically by a 180 degree peel method according to JIS Z0237:2009, which is a value measured by making a measurement sample 25mm wide and 100mm long, attaching the measurement sample to an adherend, pressurizing at 0.5MPa and 50 ℃ for 20 minutes, then leaving under the conditions of normal pressure, 23 ℃, 50% rh for 24 hours, and then measuring at a peel speed of 300 mm/minute.

3. Production of adhesive sheet

As one example of producing the scattering prevention adhesive sheet 1, a coating solution of the above-mentioned adhesive composition P is applied to the release surface of the release sheet 13, heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, and then the water-decomposable substrate 11 is bonded to the coating layer. When the curing period is required, the coating layer becomes the adhesive layer 12 by providing the curing period; when the curing period is not required, the coating layer directly becomes the adhesive layer 12. This makes it possible to obtain the scattering prevention adhesive sheet 1. The conditions for heat treatment and aging are as described above.

As a method for applying the coating solution 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, or the like can be used.

4. Use of adhesive sheet

By using the scattering prevention adhesive sheet 1 of the present embodiment, for example, a display device 10A or a display device 10B as a capacitive touch panel as shown in fig. 2 or 3 can be manufactured.

The display device 10A of the present embodiment is configured by including, in order from bottom to top, a display module 7, a film sensor 5 laminated thereon via an adhesive layer 6, a protective panel 2 with a patterned transparent conductive film 3 laminated thereon via an adhesive layer 4, and a scattering prevention adhesive sheet 1 (a peeling sheet 13 has peeled) adhered to the protective panel 2 via an adhesive layer 12. That is, in the display device 10A, the scattering prevention adhesive sheet 1 is provided on the front surface side (the side opposite to the display body module 7) of the protection panel 2.

The display device 10B of the present embodiment is configured by including, in order from bottom to top, a display module 7, a film sensor 5 laminated thereon via an adhesive layer 6, a scattering prevention adhesive sheet 1 laminated thereon via an adhesive layer 4 (a release sheet 13 has been peeled), and a patterned protective panel 2 with a transparent conductive film 3 laminated via an adhesive layer 12 of the scattering prevention adhesive sheet 1. That is, in the display device 10B, the scattering prevention adhesive sheet 1 is provided on the back surface side (display module 7 side) of the protection panel 2.

In the above-described display devices 10A and 10B, the transparent conductive film 3 is provided on the protective panel 2, but the present invention is not limited thereto, and the transparent conductive film 3 may be provided in other portions.

Examples of the display module 7 include a Liquid Crystal (LCD) module, a Light Emitting Diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper.

The adhesive layer 6 and the adhesive layer 4 may be formed of a desired adhesive or adhesive sheet, and may be formed of the same adhesive as the adhesive layer 12 of the scattering prevention adhesive sheet 1. Examples of the above-mentioned desired adhesive include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives, and among them, acrylic adhesives are preferred.

The film sensor 5 is generally composed of a base film 51 and a patterned transparent conductive film 52. The substrate film 51 is not particularly limited, and for example, a polyethylene terephthalate film, a polyethylene naphthalate film, a polycarbonate film, a polymethyl methacrylate film, a cellulose triacetate film, a polypropylene film, or the like can be used.

Examples of the transparent conductive film 52 include metals such as platinum, gold, silver, and copper; oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc oxide; indium Tin Oxide (ITO), indium oxide doped with zinc oxide, indium oxide doped with fluorine, tin oxide doped with antimony, tin oxide doped with fluorine, zinc oxide doped with aluminum, and other composite oxides; a film made of a non-oxide compound such as chalcogenide (chalcogenide), lanthanum hexaboride, titanium nitride, or titanium carbide, and among them, a film made of Indium Tin Oxide (ITO) is preferable.

In fig. 2 and 3, the transparent conductive film 52 of the film sensor 5 in the display devices 10A and 10B is located above the film sensor 5, but the present invention is not limited thereto, and may be located below the film sensor 5.

The protective panel 2 is preferably formed of a laminate including a glass plate, a plastic plate, and the like, in addition to the glass plate, the plastic plate, and the like.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, and the like. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5mm, preferably 0.2 to 2mm.

The plastic plate is not particularly limited, and examples thereof include acrylic plates and polycarbonate plates. The thickness of the plastic sheet is not particularly limited, but is usually 0.2 to 5mm, preferably 0.4 to 3mm.

In addition, a desired functional layer (a hard coat layer, an antiglare layer, or the like) may be provided on one surface or both surfaces of the glass plate or the plastic plate.

In the above-described display devices 10A, 10B, the transparent conductive film 3 is patterned and provided on the protective panel 2. As the material of the transparent conductive film 3, the same material as the transparent conductive film 52 of the film sensor 5 can be used. In general, one of the transparent conductive films 3 and 52 of the film sensor 5 forms a circuit pattern in the X-axis direction, and the other forms a circuit pattern in the Y-axis direction.

In the production of the display device 10A, the release sheet 13 of the scattering prevention adhesive sheet 1 may be peeled off, the exposed adhesive layer 12 may be attached to the front surface side (the side where the transparent conductive film 3 is not present) of the protective panel 2, and then the display device 10A may be produced by a conventional method using the protective panel 2 with the scattering prevention adhesive sheet 1, or the scattering prevention adhesive sheet 1 may be attached to the front surface side (the side opposite to the display body module 7) of the protective panel 2 after the display device (the display device 10A in a state where the scattering prevention adhesive sheet 1 is not attached) is produced by a conventional method.

In addition, when the display device 10B is manufactured, the release sheet 13 of the scattering prevention adhesive sheet 1 is peeled off, the exposed adhesive layer 12 is attached to the transparent conductive film 3 provided on the back side of the protective panel 2, and then the display device 10B can be manufactured by a conventional method using the protective panel 2 with the scattering prevention adhesive sheet 1.

In the display devices 10A and 10B, even when the protective panel 2 is broken due to a large impact such as dropping, scattering of fragments of the protective panel 2 can be prevented by the presence of the scattering prevention adhesive sheet 1 adhering to the protective panel 2.

In the case where the hydrolyzable substrate 11 of the scattering prevention adhesive sheet 1 is a cellulose acetate film and the display module 7 is a liquid crystal module, blackout can be prevented when a person visually recognizing the display devices 10A and 10B wears polarized sunglasses (particularly when the display devices 10A and 10B are in-vehicle display devices).

Further, by using the scattering prevention adhesive sheet 1 of the present embodiment, for example, a vehicle instrument panel 8 (preferably, an automobile instrument panel) shown in fig. 4 can be manufactured.

The vehicle instrument panel 8 of the present embodiment includes an instrument panel display device 81, a lid 82 covering the instrument panel display device 81, and a scattering prevention adhesive sheet 1 (the release sheet 13 is peeled) adhered to the surface side of the lid 82 (the side opposite to the instrument panel display device 81) via an adhesive agent layer 12. In the vehicle instrument panel 8 of the present embodiment, a gap is provided between the instrument panel display device 81 and the lid 82, but the present invention is not limited to this.

In the above example, the scattering prevention adhesive sheet 1 is attached to the front surface side of the cover 82, but the present invention is not limited thereto, and the scattering prevention adhesive sheet 1 may be attached to the back surface side (the side facing the instrument panel display device 81) of the cover 82.

In the vehicle instrument panel 8, even when the lid 82 is broken due to a large impact such as an accident, scattering of fragments of the broken lid 82 can be prevented by the presence of the scattering prevention adhesive sheet 1 attached to the lid 82.

In the case where the water-decomposable substrate 11 of the scattering prevention sheet 1 is a cellulose acetate film and the instrument panel display device 81 includes a liquid crystal display, blackout can be prevented when a person visually recognizing the instrument panel 8 for a vehicle wears polarized sunglasses.

The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiments also covers all design changes and equivalents that fall within the technical scope of the present invention.

For example, the release sheet 13 in the scattering prevention adhesive sheet 1 may be omitted. Further, another layer may be laminated on the surface of the hydrolyzable substrate 11 opposite to the adhesive layer 12.

The substrate of the scattering prevention adhesive sheet may be a release sheet. In this case, the adhesive layer is bonded to a member having a function of preventing scattering in a subsequent step. Further, the scattering prevention adhesive sheet may be an adhesive sheet not intended for scattering prevention, and may be an adhesive sheet for blackout prevention, for example.

Examples

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

[ example 1]

1. Preparation of (meth) acrylate Polymer (A)

The (meth) acrylic ester polymer (a) was prepared by copolymerizing 78 parts by mass of N-butyl acrylate, 15 parts by mass of isobornyl acrylate, 5 parts by mass of N-acryloylmorpholine, and 2 parts by mass of 2-hydroxyethyl acrylate by a solution polymerization method. The molecular weight of the (meth) acrylate polymer (a) was measured by the method described later, and the weight average molecular weight (Mw) was 150 ten thousand.

2. Preparation of adhesive composition

100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth) acrylate polymer (A) obtained in step 1, 1.0 part by mass of polycarbodiimide (B1) as the carbodiimide compound (B), the product name "CARBODILITE V-05", the decarbonated condensate of tetramethylxylylene diisocyanate, the content of the terminal isocyanate group: 8.2% by mass, as the carbodiimide compound (B), 0.3 part by mass of trimethylolpropane-modified xylylene diisocyanate (Soken Chemical & Engineering Co., ltd., product name "TD-75") as the crosslinking agent (C), and 0.2 part by mass of 3-glycidyloxypropyltrimethoxysilane as the silane coupling agent were mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

Here, the (meth) acrylate polymer (a) is assumed to be 100 parts by mass (solid content equivalent), and the respective compounding ratios (solid content equivalent) of the adhesive composition at this time are shown in table 1. The abbreviations and the like shown in table 1 are as follows.

[ (meth) acrylic acid ester Polymer (A) ]

BA: acrylic acid n-butyl ester

IBXA: acrylic acid isobornyl ester

ACMO: n-acryloyl morpholine

HEA: 2-Hydroxyethyl acrylate

2EHA: 2-ethylhexyl acrylate

MMA: methacrylic acid methyl ester

AA: acrylic acid

[ carbodiimide Compound (B) ]

B1: polycarbodiimide (manufactured by Nisshinbo Chemical Inc., product name "CARBODILITE V-05", decarbonated condensate of tetramethylxylylene diisocyanate, content of terminal isocyanate group: 8.2 mass%)

B2: polycarbodiimide (manufactured by Nisshinbo Chemical Inc., product name "CARBODILITE V-07", decarbonated condensate of tetramethylxylylene diisocyanate, content of terminal isocyanate group: 0.5% by mass)

B3: polycarbodiimide (product name "CARBODILITE V-09", manufactured by Nisshinbo Chemical Inc., decarbonated condensate of tetramethylxylylene diisocyanate, non-terminal isocyanate group)

[ crosslinking agent (C) ]

XDI: trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical & Engineering Co., ltd., product name "TD-75")

TDI: trimethylolpropane-modified tolylene diisocyanate (TOYOCHEM CO., LTD., product name "BHS 8515")

And (3) epoxy: 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (MITSUSHICHI GAS CHEMICAL COMPANY, INC., product name "TETRAD-C")

3. Production of scattering preventive adhesive sheet

The coating solution of the adhesive composition obtained in the above step 2 was applied to the release-treated surface of a release sheet (product name "SP-PET752150" manufactured by linec CORPORATION) obtained by performing a release treatment on one surface of a polyethylene terephthalate film using a silicone-based release agent, using a blade coater. Then, the coating layer was subjected to a heat treatment at 90 ℃ for 1 minute to form a coating layer.

Next, a Triacetylcellulose (TAC) film (product name "FUJITAC TD80ULP" with a thickness of 80 μm) as a substrate (hydrolyzable substrate) was laminated on the coating layer, and the resultant was aged at 23 ℃ and 50% rh for 7 days to prepare a scattering prevention adhesive sheet having a structure of TAC film/adhesive layer (thickness: 25 μm)/release sheet.

The thickness of the adhesive agent layer is a value measured by using a constant pressure thickness measuring instrument (TECLOCK co., ltd., product name "PG-02") in accordance with JIS K7130.

Examples 2 to 8 and comparative examples 1 to 3

A scattering prevention adhesive sheet was produced in the same manner as in example 1, except that the kind and proportion of each monomer constituting the (meth) acrylate polymer (a), the weight average molecular weight (Mw) of the (meth) acrylate polymer (a), the kind and blending amount of the carbodiimide compound (B), the kind and blending amount of the crosslinking agent (C), and the blending amount of the silane coupling agent were changed as shown in table 1.

Here, the weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured by Gel Permeation Chromatography (GPC) under the following conditions (GPC measurement).

< measurement Condition >

"measuring apparatus: HLC-8320, manufactured by TOSOH CORPORATION

"GPC chromatography column (by passing in the following order): TOSOH CORPORATION, inc

TSK gel superH-H

TSK gel superHM-H

TSK gel superH2000

"determination of solvent: tetrahydrofuran (THF)

"measurement temperature: 40 deg.C

[ test example 1] (measurement of gel fraction)

The scattering prevention adhesive sheets obtained in examples and comparative examples were cut into 80mm × 80mm pieces, the adhesive layers were wrapped in a polyester mesh (mesh size 200), the masses thereof were weighed with a precision balance, and the masses of the adhesive layers alone were subtracted therefrom to calculate the masses of the adhesives themselves. The mass at this time is denoted as M1.

Subsequently, the adhesive coated on the polyester mesh was immersed in ethyl acetate at room temperature (23 ℃) for 72 hours. The adhesive was then taken out, air-dried at a temperature of 23 ℃ and a relative humidity of 50% for 24 hours, and further dried in an oven at 80 ℃ for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the above-mentioned mesh alone was subtracted, thereby calculating the mass of the adhesive itself. The mass at this time is denoted as M2. Gel fraction (%) is expressed as (M2/M1). Times.100. The results are shown in Table 1.

[ test example 2] (measurement of Total light transmittance)

The total light transmittance (%) of the adhesive agent layer of the scattering prevention adhesive sheet obtained in examples and comparative examples was measured by using a haze meter (NIPPON DENSHOKU INDUSTRIES co., ltd., product name "NDH-5000") in accordance with JIS K7361-1-1997. The results are shown in Table 1.

[ test example 3] (measurement of adhesive force)

The release sheet was peeled from the scattering prevention adhesive sheet obtained in examples and comparative examples, and the exposed adhesive layer was attached to soda-lime glass (NIPPON SHEET GLASS co., LTD). Then, after leaving at 23 ℃ and 50% RH for 24 hours, the adhesion (mN/25 mm) was measured using a tensile tester (ORIENTEC Co., ltd., TENSILON) under conditions of a peeling speed of 300mm/min and a peeling angle of 180 degrees. The conditions not described herein were measured according to JIS Z0237: 2009. The results are shown in Table 1.

[ test example 4] (evaluation of moisture and Heat durability)

The release sheet was peeled from the scattering prevention adhesive sheet obtained in examples and comparative examples, and the exposed adhesive layer was attached to soda-lime glass (NIPPON SHEET GLASS co., LTD). Then, the mixture was pressurized at 50 ℃ under 0.5MPa for 20 minutes using an autoclave manufactured by KURIHARA. Then, the sample was left for 24 hours under conditions of 23 ℃ and 50% RH.

The obtained samples were stored under wet heat conditions of 85 ℃ and 85% RH for 1500 hours. Then, the state of the sample (fracture of the substrate, peeling of the substrate from the adhesive agent layer, and the like) was visually confirmed, and the moist heat durability was evaluated according to the following criteria. The results are shown in Table 1.

As good as …, no substrate breakage and no substrate peeling from the adhesive agent layer

Good … substrate had little cracking, but the substrate did not peel off from the adhesive layer

Cracks were generated in the delta … substrates, but the substrates did not peel from the adhesive layer

Creation of cracks on x … substrates

[ test example 5] (evaluation of fly-off prevention)

The scattering prevention adhesive sheets obtained in examples and comparative examples were bonded to a soda-lime glass plate (NIPPON SHEET GLASS CO., LTD) 170mm in length, 150mm in width, and 1mm in thickness. Then, a laminate of the glass plate and the adhesive sheet was placed on 2 tables having a height of 10 mm. At this time, the adhesive sheet side was directed upward (toward the opposite side to the stage), and the laminate was placed on the stage with the portions ranging from both ends in the longitudinal direction to 10mm, respectively, and was disposed in a state in which the central portion was suspended (height: 10 mm). Then, an iron ball having a diameter of 45mm was dropped from a height of 30cm toward the center of the laminate. The state of the laminate after that was visually observed, and the scattering prevention property was evaluated according to the following criteria. The results are shown in Table 1.

Good results of … prevent the adhesive sheet from shattering and prevent the glass from scattering.

X … fly off to prevent the adhesive sheet from chipping and glass from flying off.

As is clear from table 1, the adhesive sheets obtained in the examples are excellent in moist heat durability and scattering prevention property.

Industrial applicability

The adhesive sheet of the present invention can be suitably used as an adhesive sheet for preventing scattering and blackout of a display of a car navigation system, for example.

Claims (2)

1. A display device comprising a protective panel and a scattering prevention adhesive sheet laminated on the protective panel via an adhesive layer, characterized in that,

the adhesive sheet for preventing scattering comprises a base material and the adhesive layer provided on at least one surface side of the base material,

the base material is a hydrolytic base material,

the adhesive constituting the adhesive layer contains a polymer and, at the same time, a carbodiimide,

the adhesive has a gel fraction of 10% or more,

the acid value of the polymer is 50mgKOH/g or less,

the carbodiimide content in the adhesive is 0.01-3 mass%,

the polymer is a crosslinked product of a (meth) acrylate polymer,

the (meth) acrylate polymer is crosslinked by an isocyanate-based crosslinking agent,

the amount of the isocyanate-based crosslinking agent blended is 0.01 to 1.0 part by mass based on 100 parts by mass of the (meth) acrylate polymer.

2. The display device according to claim 1, wherein the polymer has a hydroxyl value of 1mgKOH/g or more and 300mgKOH/g or less.

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