JPWO2018174198A1 - Adhesive composition, adhesive and laminate - Google Patents

Abstract

The present invention provides an adhesive for bonding a convex surface of a substrate sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a substrate sheet [II] having a flat surface. The present invention relates to a polyester-based pressure-sensitive adhesive composition containing a polyester-based resin (A) having a glass transition temperature of 0 ° C. or lower.

Description

The present invention provides a pressure-sensitive adhesive composition for bonding a convex surface of a base sheet [I] having a convex surface and a flat surface of a substrate sheet [II] having a flat surface, particularly, prism sheets. And at least one of a pressure-sensitive adhesive composition for bonding a prism sheet and a diffusion sheet.
The present invention also relates to a pressure-sensitive adhesive using the pressure-sensitive adhesive composition and a laminate using the pressure-sensitive adhesive.

  Conventionally, an ultraviolet-curing adhesive, a thermosetting adhesive, or the like is used as an adhesive to bond a prism sheet or the like. For example, Patent Literature 1 describes “ThreeBond 3042B” as a specific example of an ultraviolet-curable adhesive, and “Sankei Epochure and Epoquick” as a specific example of a thermosetting adhesive. 5: 1 mixture ".

Japanese Patent Application Laid-Open No. 2007-155938

  However, in the technique described in Patent Document 1, when bonding prism sheets, although the adhesiveness is obtained to some extent, it is still not satisfactory, and with the advancement of technology in recent years, further bonding has been required. It is required to have a property or tackiness.

  When an ultraviolet-curing adhesive or a thermosetting adhesive is used, ultraviolet irradiation or heat treatment is required to develop the adhesive strength. In this case, however, the ultraviolet irradiation effect is uneven due to irregular reflection by a prism sheet or the like. Or the contact may move due to the expansion and contraction of the sheet due to the heat treatment, and peeling may occur. Therefore, there is a need for an adhesive that can be used for laminating prism sheets without the need for ultraviolet irradiation or heat treatment.

Under the circumstances, the present invention provides a method for bonding a convex surface of a base sheet [I] having a convex surface and a flat surface of a base sheet [II] having a flat surface under such a background. It is an object of the present invention to provide a pressure-sensitive adhesive composition which is very excellent in tackiness and can exhibit adhesive strength without requiring ultraviolet irradiation or heat treatment.
Another object of the present invention is to provide a pressure-sensitive adhesive using the pressure-sensitive adhesive composition and a laminate using the pressure-sensitive adhesive.

  However, as a result of intensive studies by the present inventors to solve the above problems, they have found that a pressure-sensitive adhesive having a pressure-sensitive adhesive composition containing a polyester-based resin exhibits extremely excellent tackiness.

  Among them, by using a pressure-sensitive adhesive having a pressure-sensitive adhesive composition containing a polyester resin having a glass transition temperature of 0 ° C. or less, when the uneven surface and the flat surface are adhered, the uneven surface is filled with the adhesive. It has been found that even a thin pressure-sensitive adhesive layer that does not end up exhibits excellent adhesiveness, and the present invention has been completed.

That is, the present invention relates to the following <1> to <9>.
<1> An adhesive for bonding a convex surface of a base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a base sheet [II] having a flat surface. A pressure-sensitive adhesive composition comprising a polyester resin (A) having a glass transition temperature of 0 ° C. or lower.
<2> The components of the polyester resin (A) include a polycarboxylic acid component (a1) and a polyol component (a2), and the aromatic polycarboxylic acid component and the aromatic polyol component in the components. The pressure-sensitive adhesive composition according to <1>, wherein the total content of is 40 mol% or less based on the total of the polyvalent carboxylic acid component (a1) and the polyol component (a2).
<3> The pressure-sensitive adhesive composition according to <1> or <2>, further comprising a crosslinking agent (B).
<4> The pressure-sensitive adhesive composition according to <3>, wherein the crosslinking agent (B) is an isocyanate-based crosslinking agent.
<5> An adhesive obtained by crosslinking the adhesive composition according to any one of <1> to <4> with a crosslinking agent (B).
<6> A base sheet [I] having a convex surface having a surface roughness Ra of 0.1 to 100 µm and a base sheet [II] having a flat surface are laminated via the pressure-sensitive adhesive described in <5>. Have a laminate.
<7> The laminate according to <6>, wherein the base sheet [I] and the base sheet [II] are each a prism sheet or a diffusion sheet.
<8> The laminate according to <6> or <7>, wherein the thickness of the pressure-sensitive adhesive layer is 10 µm or less.
<9> The convex portion of the base sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm of the pressure-sensitive adhesive composition containing the polyester resin (A) having a glass transition temperature of 0 ° C. or lower. Use for bonding a surface and a flat surface of a base sheet [II] having a flat surface.

  The pressure-sensitive adhesive composition and the pressure-sensitive adhesive of the present invention have a convex surface of a substrate sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a substrate sheet [II] having a flat surface. This is for bonding to a surface, and is extremely excellent in tackiness, and can exhibit adhesive strength without the need for ultraviolet irradiation or heat treatment.

FIG. 1 is a cross-sectional view showing a preferred embodiment of the laminate of the present invention. FIG. 2 is a schematic exploded perspective view illustrating the laminate shown in FIG. FIG. 3 is a cross-sectional view of the prism sheet 2 and the prism sheet 3 taken along the line X-X 'in the schematic exploded perspective view shown in FIG. FIG. 4 is a cross-sectional view similar to FIG. 3 except that a plurality of prisms 8 having one step higher in unevenness are arranged at regular intervals in a prism pattern 22 in the prism sheet 2 of the cross-sectional view of FIG. . FIG. 5 is a cross-sectional view showing the bonding of the diffusion sheet 1 and the prism sheet 2 of the laminate shown in FIG. 1 in more detail. 6 is a cross-sectional view of the diffusion sheet 1 and the prism sheet 2 taken along the line X-X 'in the schematic exploded perspective view shown in FIG. 2 (corresponding to the exploded view of FIG. 5).

  Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention is obtained by combining the convex surface of the base sheet [I] having the convex surface with the surface roughness Ra of 0.1 to 100 μm and the flat surface of the base sheet [II] having the flat surface. A pressure-sensitive adhesive composition for bonding, which contains a polyester resin (A) having a glass transition temperature of 0 ° C. or lower.
Here, the components of the pressure-sensitive adhesive composition will be described.

[Polyester resin (A)]
The polyester resin (A) is characterized in that the glass transition temperature is 0 ° C. or lower, and the glass transition temperature is preferably −70 to 0 ° C., particularly preferably −60 to −10 ° C., and furthermore Preferably it is -30 to -15 ° C.
When the glass transition temperature exceeds the upper limit, the pressure-sensitive adhesive layer becomes hard, and the pressure-sensitive adhesive composition of the present invention decreases in tackiness. Conversely, when the glass transition temperature is too low, the cohesive strength of the pressure-sensitive adhesive layer is reduced, and the adhesiveness of the pressure-sensitive adhesive composition of the present invention is reduced.

  The polyester resin (A) to be contained in the pressure-sensitive adhesive composition usually has a glass transition in order to increase the cohesive strength of the pressure-sensitive adhesive layer and to make it less likely to be deformed by an external load so as to increase the pressure-sensitive adhesive strength. Those whose temperature is higher than 0 ° C are selected. However, as for the pressure-sensitive adhesive composition for bonding the prism sheet, the pressure-sensitive adhesive layer should be thinner than usual, especially 10 μm or less, in order to prevent the irregularities of the prism sheet from being filled with the pressure-sensitive adhesive layer. Is required. In that case, higher flexibility and tackiness must be imparted, and the polyester resin (A) contained in the pressure-sensitive adhesive composition must have a glass transition temperature of 0 ° C or lower.

Here, the glass transition temperature (Tg) of the polyester resin is a value measured using a differential scanning calorimeter DSC Q20 manufactured by TA Instruments.
The measurement temperature range is from -90 ° C to 100 ° C, and the temperature rise rate is 10 ° C / min.

  The polyester resin (A) preferably has a copolymer component containing a polyvalent carboxylic acid component (a1) and a polyol component (a2) as a constituent component. The polyester resin (A) is preferably obtained by copolymerizing the copolymer component.

[Polyvalent carboxylic acid component (a1)]
Examples of the polycarboxylic acid component (a1) used in the present invention include:
Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid and naphthalenedicarboxylic acid;
Malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid Dicarboxylic acids such as diglycolic acid;
Alicyclics such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid Dicarboxylic acid;
And the like.
These can be used alone or in combination of two or more.

  Among these, the copolymer component preferably contains a small amount of aromatic dicarboxylic acid, and particularly preferably contains isophthalic acid, from the viewpoint of imparting an appropriate cohesive force to the pressure-sensitive adhesive layer.

  The content of the aromatic dicarboxylic acid is preferably 50 mol% or less, particularly preferably 1 to 30 mol%, and further preferably 2 to 20 mol, based on the entire polyvalent carboxylic acid component (a1). %. If the content is too high, the glass transition temperature of the polyester resin (A) becomes high, and the pressure-sensitive adhesive composition of the present invention tends to be unable to obtain sufficient pressure-sensitive adhesive performance. If the content is too low, the glass transition temperature of the polyester resin (A) becomes low, the cohesive strength becomes low, and the pressure-sensitive adhesive composition of the present invention tends to be unable to obtain sufficient pressure-sensitive adhesive performance.

  Further, from the viewpoint of imparting a tacky feeling, the copolymer component preferably contains an aliphatic dicarboxylic acid, particularly preferably contains an aliphatic dicarboxylic acid having 4 to 12 carbon atoms, and furthermore, sebacic acid It is preferable to include

  The content of the aliphatic dicarboxylic acid is preferably 40 mol% or more, particularly preferably 50 mol% to 99 mol%, more preferably 70 mol% or more, based on the entire polyvalent carboxylic acid component (a1). 98 mol%. If the content is too low, the glass transition temperature of the polyester resin (A) becomes high, and the pressure-sensitive adhesive composition of the present invention tends to be unable to obtain sufficient adhesive strength. If the content is too high, the cohesive strength tends to be too low, and the adhesive strength of the pressure-sensitive adhesive composition of the present invention tends to decrease.

  In the present invention, it is preferable to use an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid in combination as the polyvalent carboxylic acid component (a1) from the viewpoint of the balance of adhesive properties. Dicarboxylic acid / aliphatic dicarboxylic acid is preferably 1/99 to 49/51, particularly preferably aromatic dicarboxylic acid / aliphatic dicarboxylic acid = 2/98 to 30/70, more preferably aromatic dicarboxylic acid / Aliphatic dicarboxylic acid = 3/97 to 20/80.

  In order to increase the number of branch points in the polyester resin (A), a trivalent or higher polycarboxylic acid can be used. Examples of the trivalent or higher carboxylic acid include trimellitic acid and pyromellitic acid. , Adamantane tricarboxylic acid, trimesic acid and the like. Among them, it is preferable to use trimellitic acid because gelation is relatively unlikely to occur.

  The content ratio of the trivalent or higher polyvalent carboxylic acid is preferably 10 mol% or less, particularly preferably 10 mol%, based on the whole polyvalent carboxylic acid component (a1), since the cohesive force of the pressure-sensitive adhesive can be increased. Is from 0.1 to 5 mol%, and if the content is too large, gelation tends to easily occur during the production of the polyester resin (A).

[Polyol component (a2)]
As the polyol component (a2) used in the present invention, for example,
Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, , 3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6- Aliphatic diols such as hexanediol;
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, 2,2,4,4-tetramethyl-1,3 Alicyclic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol and the like Aromatic diols such as ethylene oxide and propylene oxide adducts;
And the like.
These can be used alone or in combination of two or more.

  Among these, aliphatic diols and alicyclic diols are preferable in terms of excellent reactivity, and particularly preferable examples of the aliphatic diol include ethylene glycol, diethylene glycol, 1,3-propanediol, and 2-methyl-1,3. -Propanediol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and the alicyclic diols are 1,2-cyclohexanedimethanol, 1,3-cyclohexane Dimethanol and 1,4-cyclohexanedimethanol.

  The content ratio of the aliphatic diol is preferably 99 mol% or less, particularly preferably 3 to 97 mol%, more preferably 5 to 95 mol%, based on the whole polyol component (a2). If the content is too low, the glass transition temperature of the polyester resin (A) will increase, and the adhesiveness will tend to decrease, and if the content is too high, the glass transition of the polyester resin (A) will increase. The temperature tends to decrease, the cohesive strength tends to decrease, and the adhesive strength tends to decrease.

  The content of the alicyclic diol is preferably 1 mol% or more, more preferably 3 mol% to 97 mol%, and still more preferably 5 mol% to 95 mol%, based on the whole polyol component (a2). It is. If the content is too low, the toughness tends to be low, and the adhesive strength tends to be low. If the content is too high, the solubility in a solvent tends to be low, and processing tends to be difficult.

  In the present invention, it is preferable to use an aliphatic diol and an alicyclic diol as the polyol component (a2) in view of the balance of the adhesive properties, and the content ratio (molar ratio) is aliphatic diol / alicyclic. Aliphatic diol = 45/55/1/99, particularly preferably aliphatic diol / alicyclic diol = 30 / 70-3 / 97, more preferably aliphatic diol / alicyclic diol = 15 / 85 to 5/95.

  Further, in addition to the above-mentioned aromatic diol, a small amount of an aromatic polyol such as bisphenol S or bisphenol A may be contained from the viewpoint of imparting a suitable cohesive force to the pressure-sensitive adhesive layer.

  Further, a trihydric or higher polyhydric alcohol can be used in the polyester resin (A) for the purpose of increasing the branch point. Examples of the trihydric or higher polyhydric alcohol include pentaerythritol, dipentaerythritol, and tripentaerythritol. Erythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantanetriol and the like can be mentioned.

  The content of the trihydric or higher polyhydric alcohol is preferably 10 mol% or less, particularly preferably 0.1 to 5 mol%, based on the whole polyol component (a2), and the content is too large. And the production of the polyester resin (A) tends to be difficult.

  The mixing ratio of the polyvalent carboxylic acid component (a1) and the polyol component (a2) is such that the polyol component (a2) is 1.0 to 2.0 equivalents per 1.0 equivalent of the polyvalent carboxylic acid component (a1). It is particularly preferred that the amount is 1.1 to 1.7 equivalents. If the content of the polyol component (a2) is too low, the acid value tends to be high and it is difficult to increase the molecular weight. If the content is too high, the yield tends to be low.

  The constituent components of the polyester resin (A) are arbitrarily selected from the above-mentioned polyvalent carboxylic acid component (a1) and polyol component (a2), and the total of the polyvalent carboxylic acid component (a1) and the polyol component (a2) It is preferable that the total content of the aromatic polycarboxylic acid component and the aromatic polyol component to be 40 mol% or less with respect to the content because the tackiness is increased. The content ratio is more preferably 1 to 25 mol%, and particularly preferably 2 to 20 mol%. When the content is higher than 40 mol%, the adhesive strength of the pressure-sensitive adhesive composition of the present invention tends to decrease, and when the content is too low, the adhesive strength of the pressure-sensitive adhesive composition of the present invention tends to decrease. is there.

  The polyester resin (A) is preferably produced by arbitrarily selecting the polyvalent carboxylic acid component (a1) and the polyol component (a2) and subjecting them to a polycondensation reaction in the presence of a catalyst by a known method. .

  In such a polycondensation reaction, an esterification reaction is first performed, and then a condensation reaction is performed.

  In such an esterification reaction, a catalyst is used.Specifically, catalysts such as titanium catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony catalysts such as antimony trioxide, and germanium catalysts such as germanium dioxide and Examples include catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, and germanium dioxide are preferred in view of the balance between the high catalytic activity and the hue.

  The compounding amount of the catalyst is preferably from 1 to 10,000 ppm, particularly preferably from 10 to 5,000 ppm, and further preferably from 20 to 3,000 ppm, based on all copolymer components. If the amount is too small, the polymerization reaction tends not to proceed sufficiently. If the amount is too large, there is no advantage such as a reduction in reaction time, and a side reaction tends to occur.

  The reaction temperature during the esterification reaction is preferably from 160 to 260 ° C, particularly preferably from 180 to 250 ° C, and further preferably from 200 to 250 ° C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently. If the reaction temperature is too high, side reactions such as decomposition tend to occur. In addition, the pressure during the reaction may be generally normal pressure.

After the esterification reaction is performed, a condensation reaction is performed.
As the reaction conditions for the condensation reaction, the same catalyst as that used in the above-mentioned esterification reaction is further mixed in the same amount, and the reaction temperature is preferably 220 to 280 ° C (particularly preferably 230 to 270 ° C). It is preferable to gradually reduce the pressure of the system and finally make the reaction at 5 hPa or less.
If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if the reaction temperature is too high, side reactions such as decomposition tend to occur.

  The number average molecular weight of the polyester resin (A) is preferably 5,000 or more, particularly preferably 10,000 to 100,000, and further preferably 15,000 to 80,000.

  If the number average molecular weight is too small, a sufficient cohesive force cannot be obtained as an adhesive, and the heat resistance and mechanical strength tend to decrease.If the number average molecular weight is too large, flexibility is lost, and Adhesion tends to decrease.

The above number average molecular weight is a number average molecular weight in terms of standard polystyrene molecular weight. The column is TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2) in high performance liquid chromatography (manufactured by Tosoh Corporation, “HLC-8320GPC”). × 10 ⁶ , theoretical plate number: 16,000 plates / sheet, filler material: styrene-divinylbenzene copolymer, filler particle diameter: 4 μm).

The acid value of the polyester resin (A) is preferably 5 mgKOH / g or less, particularly preferably 1 mgKOH / g or less, more preferably 0.5 mgKOH / g or less, particularly preferably 0.2 mgKOH / g or less. . If the acid value is too high, the pressure-sensitive adhesive will tend to attack the adherend, or the reaction with the cross-linking agent will be inhibited, resulting in insufficient adhesion.
The acid value of the polyester resin (A) is determined by neutralization titration based on JIS K0070.

  The polyester resin (A) has a glass transition temperature of 0 ° C. or less, and the method of reducing the glass transition temperature to 0 ° C. or less is not particularly limited, but the polymerization is performed by increasing the proportion of the monomer having a small number of functional groups. Then, the amount of the monomer having three or more functional groups is reduced so as to reduce the branching of the polyester resin (A), or the cross-linking structure generated by using a monomer having a small number of unsaturated groups is reduced. Or a method in which polymerization is carried out by increasing the proportion of a monomer having no aromatic ring or the like and having low rigidity, or the like, and these may be combined to reduce the glass transition temperature to 0 ° C. or lower.

[Crosslinking agent (B)]
The pressure-sensitive adhesive composition of the present invention contains the polyester resin (A), but preferably further contains a crosslinking agent (B).
This is because cross-linking the polyester resin (A) using the cross-linking agent (B) enhances cohesion, and can more effectively exert the performance as an adhesive.

  Examples of the crosslinking agent (B) include a crosslinking agent having a functional group that reacts with a hydroxyl group and / or a carboxyl group contained in the polyester resin (A), such as an isocyanate crosslinking agent and an epoxy crosslinking agent. Among these, an isocyanate-based cross-linking agent is particularly preferable, since it can achieve a good balance between initial tackiness, mechanical strength, and heat resistance.

  Examples of such isocyanate-based cross-linking agents include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate. Further, isocyanate adducts such as tolylene diisocyanate adduct, hexamethylene diisocyanate adduct, and isophorone diisocyanate adduct of trimethylolpropane may be mentioned. The isocyanate-based cross-linking agent may be one in which the isocyanate portion is blocked by phenol, lactam or the like. One of these crosslinking agents may be used alone, or two or more thereof may be used in combination.

  The amount of the crosslinking agent (B) can be appropriately selected depending on the molecular weight of the polyester-based resin (A) and the purpose of use. However, usually, 1 to 10 parts by weight in relation to 100 parts of the polyester-based resin (A) is used. It is preferably 1 to 5 parts, more preferably 1 to 3 parts. When the blending amount of the crosslinking agent (B) is less than 1 part, the adhesive strength tends to decrease because the hardness of the adhesive layer is insufficient, and when it is more than 10 parts, the adhesive strength tends to decrease. .

[Others]
In the pressure-sensitive adhesive composition of the present invention, in addition to the above components, within the range not impairing the effects of the present invention, an antistatic agent, a hydrolysis inhibitor, other acrylic adhesives, other adhesives, urethane resins, Tackifiers such as rosin, rosin ester, hydrogenated rosin ester, phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, etc., and plasticizers such as polyol , An antioxidant, a leveling agent, a rheology control agent, a coloring agent, a filler, an antioxidant, an ultraviolet absorber, a conventionally known additive such as a functional dye, or a color or discoloration caused by irradiation with ultraviolet light or radiation. The compounding amount of these additives is preferably 30% by weight or less of the whole pressure-sensitive adhesive composition, and particularly preferably 2% by weight or less. % By weight or less.

  The pressure-sensitive adhesive composition of the present invention contains a hydrolysis inhibitor in addition to the polyester resin (A), so that the durability under high temperature and high humidity can be expected.

The hydrolysis inhibitor is not particularly limited, and a conventionally known one can be used. Examples thereof include a compound which reacts with and binds to a carboxylic acid terminal group of the polyester resin (A). Specifically, a compound having a functional group such as a carbodiimide group, an epoxy group, and an oxazoline group is exemplified.
Among them, the carbodiimide group-containing compound is preferable because it has a high effect of eliminating the catalytic activity of the proton derived from the terminal group of the carboxyl group.

  As the carbodiimide group-containing compound, a known carbodiimide or polycarbodiimide having at least one carbodiimide group (-N = C = N-) in a molecule may be used, but durability under higher temperature and high humidity may be used. It is preferable that the compound contains two or more carbodiimide groups in the molecule, more preferably three or more, more preferably five or more, and particularly preferably seven or more in terms of increasing the number of carbodiimide groups. If the carbodiimide group contains 50 or more carbodiimide groups in the molecule, the molecular structure becomes too large, which tends to be unfavorable.

  As the carbodiimide group-containing compound, it is preferable to use a compound having a high weight average molecular weight from the viewpoint of hydrolysis resistance. The weight average molecular weight of the carbodiimide group-containing compound is preferably at least 500, more preferably at least 2,000, even more preferably at least 3,000. The upper limit of the weight average molecular weight is usually 50,000. If the weight average molecular weight of the carbodiimide group-containing compound is too small, hydrolysis resistance tends to decrease. If the weight average molecular weight of the carbodiimide group-containing compound is too large, the compatibility with the polyester resin tends to decrease.

It is also preferable to use a high molecular weight polycarbodiimide produced by subjecting a diisocyanate to a decarboxylation reaction in the presence of a carbodiimidization catalyst.
Examples of such a high molecular weight polycarbodiimide include those obtained by subjecting the following diisocyanates to a decarboxylation reaction.

  Examples of such diisocyanates include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, and 4,4'- Diphenyl ether diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4, Examples thereof include 4′-dicyclohexylmethane diisocyanate and tetramethylxylylene diisocyanate, and these can be used alone or in combination of two or more. Such a high molecular weight polycarbodiimide may be synthesized or a commercially available product may be used.

  The content of the hydrolysis inhibitor is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polyester resin (A). More preferably, it is 0.2 to 3 parts by weight. If the content is too large, turbidity tends to occur due to poor compatibility with the polyester resin (A), and if the content is too small, sufficient durability tends to be hardly obtained.

  The content of the hydrolysis inhibitor is preferably optimized in accordance with the acid value of the polyester resin (A), and the total number of moles of the acidic functional groups of the polyester resin (A) is preferable. The molar ratio ((b) / (a)) of the total number (b) of the functional group moles of the hydrolysis inhibitor in the pressure-sensitive adhesive composition to (a) is 0.5 ≦ (b) / (a). It is more preferable that 1 ≦ (b) / (a) ≦ 1,000, and it is even more preferable that 1.5 ≦ (b) / (a) ≦ 100. If the molar ratio of (b) to (a) ((b) / (a)) is too low, the wet heat resistance tends to decrease. If the molar ratio of (b) to (a) ((b) / (a)) is too high, the compatibility with the polyester resin (A) decreases, and the adhesive strength, cohesive strength, and durability are reduced. Tends to decrease.

Further, the pressure-sensitive adhesive composition of the present invention may be one in which impurities and the like contained in the raw materials for producing the components of the pressure-sensitive adhesive composition are blended in a small amount, in addition to the above-mentioned additives.
The pressure-sensitive adhesive composition of the present invention is obtained by stirring and mixing the above-mentioned components according to a known method.

  The pressure-sensitive adhesive composition of the present invention has a viscosity at 25 ° C. of usually from 1 to 100,000 mPa · s, preferably from 10 to 50,000 mPa · s, particularly from the viewpoint of coatability to a substrate. Preferably it is 50 to 30,000 mPa · s. If the viscosity is too low, unevenness tends to occur during application to the substrate, and if the viscosity is too high, application to the substrate tends to be difficult.

  Further, the pressure-sensitive adhesive composition of the present invention may contain a solvent, or may be used as a solvent-free composition, but a solvent-free type in which the step of drying the solvent in the pressure-sensitive adhesive can be omitted. It is preferable to use as a composition. In addition, when the solvent is contained, the concentration is usually 3 to 90% by weight, preferably 5 to 80% by weight, and particularly preferably 10 to 70% by weight based on the weight of the solid content of the pressure-sensitive adhesive. If the concentration is too low, the leveling property tends to decrease when applied to the substrate, and if the concentration is too high, the viscosity tends to increase and the coating tends to be difficult.

  Examples of such a solvent include alcohols such as methanol, ethanol, propanol, n-butanol and i-butanol, ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone and cyclohexanone, cellosolves such as ethyl cellosolve, toluene, xylene and the like. Aromatics, glycol ethers such as propylene glycol monomethyl ether, methyl acetate, ethyl acetate, acetates such as butyl acetate, diacetone alcohol and the like, and these solvents may be used alone or Two or more kinds may be used in combination.

<Adhesive>
The pressure-sensitive adhesive of the present invention is obtained by cross-linking the pressure-sensitive adhesive composition of the present invention with the cross-linking agent (B) described above.
That is, the pressure-sensitive adhesive composition of the present invention preferably functions as a pressure-sensitive adhesive when the polyester resin (A) is cross-linked by the cross-linking agent (B). It can be suitably used as an adhesive.

The pressure-sensitive adhesive of the present invention preferably does not substantially contain an acidic group. Specifically, the pressure-sensitive adhesive preferably has an acid value of 10 mgKOH / g or less, particularly preferably 1 mgKOH / g or less, more preferably 0.1 mgKOH / g or less.
The acid value of the pressure-sensitive adhesive can be determined in the same manner as the acid value of the polyester resin (A).

<Laminate>
The laminate of the present invention is obtained by laminating the base sheet [I] and the base sheet [II] via the pressure-sensitive adhesive of the present invention.
The laminate of the present invention obtained by laminating the base sheet [I] and the base sheet [II] using the pressure-sensitive adhesive of the present invention is a laminate having little peeling of the pressure-sensitive adhesive layer and excellent in stability over time. Body.

  As the substrate sheet [I], at least one surface of the sheet has a convex surface having a surface roughness Ra of 0.1 to 100 μm, and the convex surface includes a plurality of convex portions. May be constant or different. In addition, examples of the shape of the convex portion include a dot, a stripe, and a lattice, and a stripe shape is particularly preferable from the viewpoint of both optical properties and adhesiveness.

  The base sheet [I] is a lens sheet in which convex lenses formed in one axis direction are arranged adjacent to each other substantially over the entire surface, a so-called prism sheet, or a diffusion sheet in which irregularities are randomly formed. Is particularly preferred. Examples of the prism sheet include a prism sheet having a pitch of 60 μm, an average height of irregularities of 30 μm, and an apex angle of a convex portion of 90 degrees (right angle).

  The measurement of the surface roughness Ra (μm) is in accordance with JIS B 0601 (1982) and the average roughness of the center line. In the case of a prism sheet or a diffusion sheet, the average height of the irregularities corresponds to this. I do.

  The material and manufacturing method of such a base sheet [I] can employ various known modes. For example, a sheet-shaped resin material extruded from a die is transferred to a concave transfer roller (an inverted mold of a convex surface is formed on the surface) rotating at substantially the same speed as the extrusion speed of the resin material, A method of manufacturing a resin sheet can be adopted in which the sheet is nipped by a nip roller plate that is disposed to face and rotates at the same speed, and the uneven shape of the transfer roller surface is transferred to a resin material.

  Further, a method of manufacturing a resin sheet can be adopted in which a transfer die plate (stamper) having a reversal of the convex surface formed on the surface thereof by hot pressing and a resin plate are laminated, and press-formed by thermal transfer.

  As a resin material used in such a production method, a thermoplastic resin can be used, and examples thereof include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyolefin, acrylic resin, and polystyrene. , Polycarbonate, polyamide, polyester resin such as PET (polyethylene terephthalate), biaxially stretched polyethylene terephthalate, polyethylene naphthalate, polyamide imide, polyimide, aromatic polyamide, cellulose acylate, cellulose triacetate, cellulose acetate propionate And cellulose diacetate, but an acrylic resin is preferred in terms of optical properties and reaction rate.

  Further, as another manufacturing method, the unevenness of the surface of an uneven roller (an inverted type of a convex portion is formed on the surface) is transferred to a surface of a transparent film (for example, a film made of the thermoplastic resin). A method of manufacturing a resin sheet can be adopted.

  On the other hand, as the substrate sheet [II], as long as at least one surface of the sheet has a flat surface, the other surface may have a convex shape shown in the substrate sheet [I]. Good. Here, the flat surface refers to a flat surface having no unevenness, and preferably has a surface roughness Ra of less than 0.1 μm. The lower limit of the surface roughness Ra is usually 0.001 μm.

  Examples of such a base sheet [II] include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyolefin, acryl, polystyrene, polycarbonate, polyamide, PET (polyethylene terephthalate) and PEN (polyethylene). Polyester resins such as naphthalate), polymethyl methacrylate, polyether ether ketone, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, biaxially stretched polyethylene terephthalate, polyamide imide, polyimide, aromatic polyamide, cellulose acylate A known transparent film made of a material such as cellulose triacetate, cellulose acetate propionate, and cellulose diacetate can be used.

  Of these, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acrylics such as cellulose acylate and polymethyl methacrylate, polycarbonates, and polyolefins such as polypropylene and cyclic polyolefins can be preferably used. Among these, polyester resins are preferred in terms of optical properties and workability.

  Further, as the base sheet [II], a sheet in which one surface is the convex surface shown in the base sheet [I] and the other surface is a flat surface can be used. In particular, in order to obtain an optical sheet, the base sheet [II] is preferably a prism sheet or a diffusion sheet.

In order to obtain a better optical sheet, both the base sheet [I] and the base sheet [II] are prism sheets, or the base sheet [I] is a diffusion sheet and the base sheet [II] ] Is preferably a prism sheet, and the base sheet [I] is a prism sheet and the base sheet [II] is a diffusion sheet.
The pressure-sensitive adhesive composition of the present invention can exhibit extremely excellent adhesion in the adhesion between the prism sheets and the adhesion between the prism sheet and the diffusion sheet, which were conventionally difficult to obtain a sufficient adhesion.

  When both the base sheet [I] and the base sheet [II] are prism sheets, they are arranged in a direction in which the axes of the convex lenses (prisms) are substantially orthogonal to each other. That is, when the axes of the convex lenses of the prism sheet of the base sheet [I] are arranged in the vertical direction, the axes of the convex lenses of the prism sheet of the base sheet [II] are arranged in the parallel direction. .

  FIG. 1 shows a cross-sectional view of one preferred embodiment of the laminate of the present invention. The laminated body shown in FIG. 1 includes, in order from the bottom, a diffusion sheet 1, a cured body 5 of an adhesive composition, a prism sheet 2, a cured body 5 of an adhesive composition, a prism sheet 3, and a cured body 5 of an adhesive composition. , A diffusion sheet 4. The form in which the base sheet [I] and the base sheet [II] are both prism sheets is exemplified between the prism sheet 2 and the prism sheet 3, and the base sheet [I] is a prism sheet. The form in which the base sheet [II] is a diffusion sheet is exemplified between the prism sheet 3 and the diffusion sheet 4, and the base sheet [I] is a diffusion sheet and the base sheet [II] is a prism sheet. Is exemplified between the diffusion sheet 1 and the prism sheet 2. FIG. 5 is a diagram showing the bonding of the diffusion sheet 1 and the prism sheet 2 in more detail.

  FIG. 2 is a schematic exploded perspective view for explaining the laminate shown in FIG. 1 (the cured body 5 is not shown), and the prism sheet 2 and the prism sheet 3 are taken along the line XX ′ shown in FIG. FIG. 3 shows a cut-away cross-sectional view.

  Here, the diffusion sheet 1 and the diffusion sheet 4 and the prism sheet 2 and the prism sheet 3 are manufactured by forming irregularities on the resin material using a concave transfer roller, a transfer mold plate (stamper), a concave and convex roller, or the like, as described above. can do.

  In addition, the diffusion sheet 1 and the diffusion sheet 4 are made of a transparent film (support) such as a PET film, a polycarbonate film, or polystyrene, and a plurality of light-diffusing beads on the surface (one surface) of an acrylic resin, epoxy resin, or the like. It can also be manufactured by fixing with a binder such as a resin, a urethane resin or an olefin resin, and has a predetermined light diffusion performance. The diffusion sheet 1 and the diffusion sheet 4 are used mainly for the purpose of reducing luminance unevenness in the backlight surface.

  Examples of the beads include acrylic beads, silica beads, barium sulfate, titanium oxide, calcium silicate, and the like. For example, TDF-127 (manufactured by Toray Seihan), Opulse BS-080 (manufactured by Ewa), D141 (manufactured by Tsudiden) and the like can be mentioned.

  Further, the average particle size of the beads is preferably 100 μm or less, particularly preferably 50 μm or less, and further preferably 25 μm or less. Further, it is preferable that the diffusion sheet 1 and the diffusion sheet 4 have different average particle diameters of beads and have different light diffusion performances.

  Further, as the above-mentioned prism sheet 2 and prism sheet 3, for example, those in which an array-like prism pattern 22 and prism pattern 32 are formed on the surface of a base material 21 and a base material 31 such as a PET film, a polycarbonate film, and polystyrene are used. Often, it is used mainly for the purpose of condensing the light of the backlight and improving the luminance.

  As a material of the prism patterns 22 and 32, an acrylic photopolymer, polycarbonate, a fluorene-based resin, or the like is used, but is not limited thereto. In addition, the prism patterns 22 and 32 need not be strictly prismatic, but may be R-shaped on the top, wave film, or downward prismatic.

  In the laminate of FIG. 1, the prism sheet 2 and the prism sheet 3 are adhered to each other by the cured body 5 of the pressure-sensitive adhesive composition of the present invention. Specifically, a pressure-sensitive adhesive composition is applied as a thin film on the flat surface of one prism sheet 3, and this prism sheet 3 is coated with the pressure-sensitive adhesive composition to form a prism pattern surface (convex surface) of the other prism sheet 2. And is cured by curing the pressure-sensitive adhesive composition. At this time, the prism sheet 2 and the prism sheet 3 are point-joined or line-joined by the projections of the prism sheet 2.

  Further, the diffusion sheet 1 and the prism sheet 2 in FIG. 1 may be adhered by the cured body 5 of the pressure-sensitive adhesive composition of the present invention. Specifically, a pressure-sensitive adhesive composition is applied as a thin film on the flat surface of one of the prism sheets 2, and the prism sheet 2 is bonded to the convex surface of the diffusion sheet 1 using the pressure-sensitive adhesive composition. By curing the agent composition, it is possible to adhere (FIG. 5).

  FIG. 3 is a cross-sectional view of the prism sheet 2 and the prism sheet 3 in the schematic exploded perspective view of FIG. 2 taken along the line X-X ′ shown in FIG. As shown in the cross-sectional view of FIG. 3, the prism pattern 22 of the prism sheet 2 and the prism pattern 32 of the prism sheet 3 may include a plurality of protrusions (prisms) having the same uneven height. The prism pattern 22 of the prism sheet 2 and the prism pattern 32 of the prism sheet 3 may be prism patterns having the same uneven height, or may be different.

  In another embodiment, as shown in the prism sheet 2 of FIG. 4, a plurality of projections (prisms) 8 one step higher than the prism pattern 22 having the same uneven height are arranged at regular intervals in the prism pattern 22. A prism sheet may be used.

  As shown in FIG. 4, when a plurality of convex portions (prisms) 8 higher than the prism pattern 22 are arranged at regular intervals, only the higher convex portions (prisms) 8 are bonded. Of the plurality of protrusions, the interval at which the higher protrusions (prisms) 8 are provided is from 1/3 (one of the three protrusions is set to a higher protrusion) to 1/3 from the viewpoint of improving luminance. 10 (one of the ten convex portions is set to a higher convex portion).

  FIG. 6 is a cross-sectional view of the diffusion sheet 1 and the prism sheet 2 in the schematic exploded perspective view of FIG. 2 taken along the line X-X ′ shown in FIG. FIG. 6 corresponds to the exploded view of FIG. 5 showing the combination of the diffusion sheet 1 and the prism sheet 2 in detail. As shown in the cross-sectional view of FIG. 6, the prism pattern 22 of the prism sheet 2 has a regular pattern, and the diffusion layer 9 of the diffusion sheet 1 has a random pattern. The height and shape of the prism patterns 22 and 32 may be uniform or non-uniform. The shape of the diffusion layer 9 may be random or regular.

(Laminated body manufacturing method)
The method for producing a laminate of the present invention includes a step of laminating a base sheet [I] and a base sheet [II] using the above-mentioned pressure-sensitive adhesive composition, and a step of curing the above-mentioned pressure-sensitive adhesive composition. Is provided.

  Specifically, usually, a liquid adhesive composition is uniformly applied to the flat surface of the base material sheet [II], and then the adhesive composition is applied to the convex surface of the base material sheet [I] via the adhesive composition. By performing bonding, pressure bonding, and aging, the pressure-sensitive adhesive composition is cured, and a laminate is obtained.

  In applying such an adhesive composition to the flat surface of the base sheet [II], for example, a reverse coater, a gravure coater (direct, reverse, offset), a bar reverse coater, a roll coater, a die coater, a bar coater, A rod coater or the like can be used, or coating by a dipping method can be performed.

  For such bonding and pressure bonding, for example, a roll laminator or the like can be used, and the pressure is selected from the range of 0.1 to 10 MPa.

  The aging treatment may be any as long as the pressure-sensitive adhesive composition can be cured by a crosslinking reaction or the like to form a pressure-sensitive adhesive layer having an appropriate cohesive force. The conditions of the aging treatment are not particularly limited, but are preferably 15 to 60 ° C, more preferably 30 to 50 ° C, preferably 1 day or more, more preferably 1 to 10 days, and still more preferably 2 to 8 days. Is preferably performed.

  The thickness of the pressure-sensitive adhesive layer in the laminate of the present invention obtained as described above is preferably 10 μm or less, and more preferably 0.01 to 10 μm. If the thickness is too small, the cohesive force of the adhesive layer itself is not obtained, and the adhesive strength tends to be not obtained.If the thickness is too large, the adhesive enters the concave portion of the prism, and the performance as a prism is reduced. Tend to. The pressure-sensitive adhesive composition of the present invention can exhibit good tackiness even with such a thin pressure-sensitive adhesive layer.

  The pressure-sensitive adhesive composition of the present invention becomes a pressure-sensitive adhesive excellent in initial and time-dependent adhesive strength, and comprises a base sheet [I] having a convex surface and a base sheet [II] having a flat surface. It is used for laminating a flat surface, and among these, it is particularly suitable for laminating prism sheets (illustrated in FIG. 3) and laminating prism sheet and diffusion sheet (illustrated in FIG. 6). It shows good adhesiveness without being influenced by the moisture content of the prism sheet itself.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.
In the examples, “parts” and “%” mean on a weight basis.

  Prior to Examples and Comparative Examples, each component of the pressure-sensitive adhesive composition shown below and a base sheet were prepared.

[Synthesis example of polyester resin (A-1)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectification tower, a nitrogen inlet tube and a vacuum device, 9.6 parts of isophthalic acid and 46.8 parts of sebacic acid as a polycarboxylic acid component (a1), and a polyol component (a2 27.1 parts of neopentyl glycol, 13.0 parts of 1,4-butanediol, 3.0 parts of 1,6-hexanediol and 0.5 part of trimethylolpropane, and 0.01 part of tetrabutyl titanate as a catalyst. Charged, the temperature was gradually raised to an internal temperature of 250 ° C., and the esterification reaction was carried out for 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polycondensation reaction was carried out for 3 hours to obtain a polyester resin (A-1) (glass transition temperature). -50 DEG C., number average molecular weight 21,000, aromatic component ratio 10 mol%).

In addition, the glass transition temperature was measured by the method described below.
The “aromatic component ratio” refers to the aromatic polycarboxylic acid component based on the total of the polycarboxylic acid component (a1) and the polyol component (a2) in the constituent components of the polyester resin (A). And the total content (mol%) of the aromatic polyol component.

[Production of pressure-sensitive adhesive composition 1]
In 100 parts of the polyester resin (A-1) solution (50 parts of solid content), as a crosslinking agent (B), 3 parts of an isocyanate-based crosslinking agent (“Coronate L55E”, manufactured by Nippon Polyurethane Co., Ltd., solid content ratio 55%), After mixing 1 part of a hydrolysis inhibitor (manufactured by Nisshinbo Chemical Inc., "Carbodilite V-07", solid content ratio: 50%), the mixture was stirred to obtain a pressure-sensitive adhesive composition 1.

[Synthesis Example of Polyester Resin (A-2), Production of Adhesive Composition 2]
In a reaction vessel equipped with a thermometer, a stirrer, a rectification tower, a nitrogen inlet tube and a vacuum device, 9.6 parts of isophthalic acid, 23.3 parts of sebacic acid, and 21. azelaic acid as a polycarboxylic acid component (a1). 7 parts, 1.8 parts of ethylene glycol as polyol component (a2), 43.6 parts of 1,4-cyclohexane dimethanol, and 0.02 part of germanium dioxide as a catalyst were gradually charged, and the temperature was gradually raised to an internal temperature of 250 ° C. The esterification reaction was performed for 4 hours. Thereafter, the internal temperature was raised to 270 ° C., the pressure was reduced to 1.33 hPa, and the polycondensation reaction was carried out for 3 hours, and the polyester resin (A-2) (glass transition temperature −25 ° C., number average molecular weight 27,000, aromatic resin) (Component ratio 10 mol%).
In the same manner as described above, a crosslinking agent (B) and a hydrolysis inhibitor were added to obtain a pressure-sensitive adhesive composition 2.

[Synthesis Example of Polyester Resin (A-3), Production of Adhesive Composition 3]
In a reaction vessel equipped with a thermometer, a stirrer, a rectification tower, a nitrogen inlet tube and a vacuum device, 19.0 parts of terephthalic acid, 19.0 parts of isophthalic acid, and 18 parts of sebacic acid were used as the polycarboxylic acid component (a1). Then, 4.0 parts of ethylene glycol, 12.0 parts of diethylene glycol, 28.0 parts of neopentyl glycol and 0.02 part of germanium dioxide were charged as the polyol component (a2), and the internal temperature was gradually raised to 250 ° C. And the esterification reaction was carried out for 4 hours. Thereafter, the internal temperature was raised to 270 ° C., the pressure was reduced to 1.33 hPa, and the polycondensation reaction was carried out for 3 hours to obtain a polyester resin (A-3) (glass transition temperature: 4 ° C., number average molecular weight: 16,000, aromatic component) 36 mol%).
The crosslinking agent (B) was added in the same manner as described above to obtain a pressure-sensitive adhesive composition 3.

[Synthesis Example of Polyester Resin (A-4), Production of Adhesive Composition 4]
21.0 parts of terephthalic acid, 16.6 parts of isophthalic acid, and 23 parts of adipic acid were added as a polycarboxylic acid component (a1) to a reaction vessel equipped with a thermometer, a stirrer, a rectification column, a nitrogen inlet tube, and a vacuum device. 0.01 part, ethylene glycol 18.4 parts, neopentyl glycol 21.0 parts as a polyol component (a2), and germanium dioxide 0.02 parts as a catalyst, gradually raise the temperature to an internal temperature of 250 ° C., and take 4 hours. To carry out an esterification reaction. Thereafter, the internal temperature was raised to 270 ° C., and the pressure was reduced to 1.33 hPa, and the polycondensation reaction was carried out for 3 hours. The polyester resin (A-4) (glass transition temperature: 11 ° C., number average molecular weight: 25,000, aromatic component) Ratio 30 mol%).
The crosslinking agent (B) was added in the same manner as described above to obtain a pressure-sensitive adhesive composition 4.

[Synthesis example of acrylic resin (A'-5), production of pressure-sensitive adhesive composition 5]
310 g of ethyl acetate and 0.19 g of azobisisobutyronitrile (AIBN) were added as solvents to a 2 L round-bottom four-necked flask, and the temperature of the water bath was raised to 90 ° C. with stirring to reflux. 459.5 g of butyl acrylate (BA) was previously placed in a glass bottle having a capacity of 1 L. 40 g of acrylic acid (AAc) and 0.5 g of 2-hydroxyethyl methacrylate (HEMA) were mixed, and the whole amount of the mixed monomer was dropped into the flask over 2 hours. One hour after the completion of the dropwise addition, 0.40 g of AIBN and 70 g of toluene were added thereto, and the mixture was further reacted for 2 hours to obtain an acrylic resin (A'-5) solution. The glass transition temperature of the acrylic resin (A′-5) was −28 ° C., the weight average molecular weight was 87,770, and the degree of dispersion was 4.9.
In the same manner as described above, the crosslinking agent (B) was added to obtain a pressure-sensitive adhesive composition 5.

<Measurement of glass transition temperature>
10 mg of the above polyester resin and acrylic resin as a measurement sample was placed in an aluminum pan, and the temperature was changed from 25 ° C to 100 ° C at a rate of 10 ° C / min using a differential scanning calorimeter (DSC Q20 manufactured by TA Instruments). After the temperature was raised and kept at 100 ° C. for 10 minutes, it was cooled at a rate of 10 ° C./min to −90 ° C. and kept at −90 ° C. for 15 minutes. An extension line of the two baselines is drawn on the DSC curve when the temperature is raised again to 100 ° C. at 10 ° C./min, and a straight line that is equidistant in the vertical axis direction is drawn between the two extension lines. And the temperature at the intersection of the DSC curves were defined as the glass transition temperature.

[Example 1]
As the base sheet [I], a prism sheet (SPX3 manufactured by Suntec Opto Co., Ltd., surface roughness: 7 to 8 μm) is used. As the base sheet [II], a 38 μm thick biaxially stretched PET film (EMBLETS manufactured by Unitika Ltd., flat) Side) was prepared.

  The pressure-sensitive adhesive composition 1 is coated on a base sheet [II] using an applicator so that the pressure-sensitive adhesive layer has a thickness of 10 μm, and the coated surface and the prism sheet surface of the base sheet [I] are coated. Were bonded together with a 2 kg hand roller. Thereafter, by performing an aging treatment at 40 ° C. for 7 days, the pressure-sensitive adhesive composition layer was crosslinked to form a pressure-sensitive adhesive layer, and the base sheet [I] and the base sheet [II] were laminated via the pressure-sensitive adhesive. A laminate was obtained.

[Example 2 and Comparative Examples 1 to 3]
Each laminated body was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive composition shown in Table 1 below was used instead of the pressure-sensitive adhesive composition 1.

  Using each of the laminates obtained above, performance evaluation was performed as follows, and the results are shown in Table 1.

[Peeling strength evaluation]
Each of the laminates obtained above was cut into a size of 15 cm × 2.5 cm, and a 180 ° peel strength (N / 25 mm) was measured at room temperature of 23 ° C. according to the measuring method of adhesive strength in JIS Z 0237.

  From the results shown in Table 1, the laminates of Examples 1 and 2 each have a 180 ° peel strength, and are comparative examples in which a pressure-sensitive adhesive composition using a polyester resin having a glass transition temperature higher than 0 ° C. is applied. Although the laminates of 1 and 2 and the glass transition temperature are 0 ° C. or lower, both have excellent adhesiveness as compared with the laminate of Comparative Example 3 in which the adhesive composition using an acrylic resin is applied. Do you get it.

  Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on March 24, 2017 (Japanese Patent Application No. 2017-059469), the contents of which are incorporated herein by reference.

  The pressure-sensitive adhesive composition of the present invention has an extremely high tackiness in bonding the convex surface of the base sheet [I] having the convex surface and the flat surface of the base sheet [II] having the flat surface. Because it is excellent, it can be used for bonding various optical films or sheets and bonding electronic parts, precision instruments, packaging materials, display materials, and the like, in addition to the adhesive for prism sheets.

DESCRIPTION OF SYMBOLS 1 Diffusion sheet 2 Prism sheet 3 Prism sheet 4 Diffusion sheet 5 Cured body of adhesive composition 8 Higher convex part (prism)
Reference Signs List 11 base material 12 diffusion layer 21 base material 22 prism pattern 31 base material 32 prism pattern 41 base material 42 diffusion layer

Claims (9)

  A pressure-sensitive adhesive composition for bonding a convex surface of a substrate sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a flat surface of a substrate sheet [II] having a flat surface. An adhesive composition containing a polyester resin (A) having a glass transition temperature of 0 ° C. or lower.   The component of the polyester resin (A) contains a polyvalent carboxylic acid component (a1) and a polyol component (a2), and the total of the aromatic polyvalent carboxylic acid component and the aromatic polyol component in the component is The pressure-sensitive adhesive composition according to claim 1, wherein the content is 40 mol% or less based on the total of the polycarboxylic acid component (a1) and the polyol component (a2).   The pressure-sensitive adhesive composition according to claim 1, further comprising a crosslinking agent (B).   The pressure-sensitive adhesive composition according to claim 3, wherein the crosslinking agent (B) is an isocyanate-based crosslinking agent.   An adhesive, wherein the adhesive composition according to any one of claims 1 to 4 is cross-linked by a cross-linking agent (B).   A substrate sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm and a substrate sheet [II] having a flat surface are laminated via the pressure-sensitive adhesive according to claim 5. Laminate.   The laminate according to claim 6, wherein the base sheet [I] and the base sheet [II] are a prism sheet or a diffusion sheet, respectively.   The laminate according to claim 6, wherein the pressure-sensitive adhesive layer has a thickness of 10 μm or less.   A convex surface of a base material sheet [I] having a convex surface with a surface roughness Ra of 0.1 to 100 μm of an adhesive composition containing a polyester resin (A) having a glass transition temperature of 0 ° C. or lower; Use for bonding a flat surface of a substrate sheet [II] having a flat surface.

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