JP7679864B2 - Polyester-based pressure-sensitive adhesive composition, pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and optical member with pressure-sensitive adhesive layer - Google Patents

Description

The present invention relates to a polyester-based pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical component with a pressure-sensitive adhesive layer, and more specifically to a polyester-based pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical component with a pressure-sensitive adhesive layer that are excellent in adhesive strength and adhesion to a substrate while also exhibiting little yellowing and excellent ultraviolet absorption ability.

Plasma display (PDP), liquid crystal display (LCD), organic light emitting display (OLED), electrophoretic display (EPD), interferometric modulation display (IMOD)
Such image display devices are composed of various members, and adhesives or adhesive sheets are used to bond and integrate such image display device components. For example, in a touch panel display, image display device components such as a surface protection panel, a touch panel, and an image display panel are used, and adhesives or adhesive sheets are used when stacking these components.

For example, in Patent Document 1, a transparent adhesive sheet for attaching a surface protective layer or a touch panel in an image display device to a display surface of an image display unit, or a transparent adhesive sheet for attaching a surface protective layer to a touch panel, is disclosed that contains (A) a (meth) alkyl group having 4 to 18 carbon atoms.
(B) an alkyl acrylate ester, (B) a polar monomer having a homopolymer glass transition temperature (Tg) of 50° C. or higher, and (C) a (meth)acrylic acid ester represented by a specific formula,
Alternatively, a transparent adhesive sheet has been proposed, which contains a copolymer of a monomer including a hydrophilic monomer whose homopolymer has a glass transition temperature (Tg) of 10°C or lower, has a tan δ of 0.13 or higher at 140°C and 1.0 Hz, and has a storage modulus of 8.9 x ¹⁰⁴ Pa or lower at 25°C and 1.0 Hz.

JP 2010-163591 A

However, the technology disclosed in Patent Document 1 and the adhesives that have been studied so far are acrylic adhesives containing acrylic resins, and since the acrylic resin itself is soft, these acrylic adhesives require improvement in terms of impact resistance. However, designing the acrylic resin to be hard in order to impart impact resistance leads to a decrease in adhesive strength and a decrease in adhesion to the substrate.

In recent years, with the trend towards lighter and thinner displays, there has been an increase in the number of touch panel functions that have been achieved by lamination, such as the in-cell method, in which touch panel electrodes are built into the liquid crystal pixels, and the on-cell method, in which electrodes are provided directly on the glass substrate or protective panel of the liquid crystal module to provide touch panel functions. These methods are called "touch-on-lens method" and are used to directly integrate the touch panel function into the liquid crystal module.
Also called. ) and others have been newly proposed, in the above-mentioned in-cell, on-cell, and touch-on-lens type configurations, the surface protection panel and the liquid crystal module are attached with one type of adhesive material, so the functions required for attaching the surface protection panel and the functions required for attaching to the liquid crystal module must be achieved with one adhesive sheet or adhesive, and more functions than before are required. In particular, display module manufacturers are expected to incorporate optical functions, etc. obtained by bonding functional films such as polarizing films and phase difference films, other than touch panels, directly into the liquid crystal module and other components, thereby reducing the number of components as much as possible. With the simplification of the functional layers of these functional films and changes in the module configuration, the adhesive sheet is also required to have ultraviolet light blocking properties to protect these functional layers.

Under these circumstances, the present invention aims to provide a polyester-based pressure-sensitive adhesive composition that uses a polyester-based resin as an adhesive instead of an acrylic resin and that has excellent adhesive strength and adhesion to substrates while also exhibiting little yellowing and excellent ultraviolet absorption ability, and further aims to provide a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and an optical component with a pressure-sensitive adhesive layer.

However, in view of these circumstances, the present inventors conducted extensive research and discovered that by adding an ultraviolet absorber having a small hydroxyl value to a pressure-sensitive adhesive composition containing a polyester resin, it is possible to obtain a polyester-based pressure-sensitive adhesive composition which has excellent adhesive strength and adhesion to substrates, is less prone to yellowing, and has excellent ultraviolet absorption ability, thereby completing the present invention.

That is, a first gist of the present invention is a polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin [I] containing a structural unit derived from a polyvalent carboxylic acid (A) and a structural unit derived from a polyol (B), and an ultraviolet absorber [II], wherein the ultraviolet absorber [II] is an ultraviolet absorber having a hydroxyl value of 900 mg KOH/g or less.

In addition, a second gist of the present invention is a pressure-sensitive adhesive obtained by crosslinking the polyester-based pressure-sensitive adhesive composition, a third gist of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and a fourth gist of the present invention is an optical member with a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer and an optical member, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive.

In the present invention, it is not the case that any ultraviolet absorbent can be used as the ultraviolet absorbent to be contained in the polyester-based resin, but it has been found that an ultraviolet absorbent with a small hydroxyl value works well in combination with a polyester-based resin. Normally, such ultraviolet absorbents contain hydroxyl groups and have a large hydroxyl value because they have excellent ultraviolet absorption performance in the long wavelength region, but by deliberately incorporating an ultraviolet absorbent with a small hydroxyl value, it is unexpectedly possible to achieve excellent ultraviolet absorption in the long wavelength region without impairing the adhesive strength, and also to achieve excellent yellowing resistance, thereby achieving the object of the present invention.

The polyester-based pressure-sensitive adhesive composition of the present invention comprises a polyester-based resin [I] containing a structural unit derived from a polyvalent carboxylic acid (A) and a structural unit derived from a polyol (B), and an ultraviolet absorber [
The ultraviolet absorber [II] has a hydroxyl value of 900 mgKOH/g or less. Therefore, the adhesive has excellent adhesive strength and adhesion to a substrate, is less yellowed, and has excellent ultraviolet absorbing ability, and is particularly useful as an adhesive for optical members.

The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments.
In the present invention, the term "carboxylic acids" includes not only carboxylic acids but also carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters.

The polyester-based pressure-sensitive adhesive composition of the present invention (hereinafter sometimes referred to as "pressure-sensitive adhesive composition") is
The pressure-sensitive adhesive composition of the present invention is characterized by containing a polyester resin [I] and a specific ultraviolet absorber [II]. The pressure-sensitive adhesive composition of the present invention preferably contains the polyester resin [I] and the specific ultraviolet absorber [II] as essential components, and also contains at least one of a hydrolysis inhibitor [III] and a crosslinking agent [IV].
It is more preferable that the compound contains both of the above.
Each of the components constituting the pressure-sensitive adhesive composition of the present invention will be described below in order.

<Polyester-based resin [I]>
The polyester-based resin [I] is usually obtained by copolymerizing copolymerization components containing polyvalent carboxylic acids (A) and polyol (B) as constituent raw materials, and the polyester-based resin [I] has, as its resin composition, structural units derived from the polyvalent carboxylic acids (A) and structural units derived from the polyol (B).

[Polyvalent Carboxylic Acids (A)]
Examples of the polyvalent carboxylic acids (A) used as a constituent raw material of the polyester resin [I] include divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids. Divalent carboxylic acids are preferably used since they can stably produce the polyester resin [I].

Examples of the divalent carboxylic acids include aliphatic dicarboxylic acids such as malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, and 1,9-nonanedicarboxylic acids;
Phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids,
aromatic dicarboxylic acids such as 4,4'-oxydibenzoic acids, and further naphthalenedicarboxylic acids such as 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, and 2,7-naphthalenedicarboxylic acids;
1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1
,3-cyclopentanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5
Alicyclic dicarboxylic acids such as norbornanedicarboxylic acids and adamantanedicarboxylic acids;
etc.
Examples of the trivalent or higher polyvalent carboxylic acids include trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, and trimesic acids.
These polyvalent carboxylic acids (A) can be used alone or in combination of two or more kinds.

Among the polyvalent carboxylic acids (A), from the viewpoint of decreasing the crystallinity of the polyester resin [I], it is preferable to contain aromatic polyvalent carboxylic acids, particularly asymmetric aromatic dicarboxylic acids (A-1), and examples of the asymmetric aromatic dicarboxylic acids (A-1) include phthalic acids, isophthalic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids, etc. Among them, isophthalic acids are particularly preferable from the viewpoint of reactivity.

The content of such aromatic polycarboxylic acids, particularly the asymmetric aromatic dicarboxylic acids (A-1), is preferably 1 to 90 mol % based on the total amount of the polycarboxylic acids (A),
In particular, the content is preferably 5 to 80 mol%, more preferably 10 to 70 mol%, particularly preferably 15 to 60 mol%, and even more preferably 20 to 50 mol%. If the content is too low, the adhesive strength at high temperatures tends to decrease, the resin tends to crystallize, and sufficient adhesive performance tends to be unavailable, whereas if the content is too high, the initial adhesive strength (tack) tends to decrease.

In the present invention, from the viewpoint of improving the initial adhesive strength (tack), it is preferable to contain, as the polyvalent carboxylic acid (A), an aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms (including the carbon of the carboxy group), and among these, it is more preferable to contain an aliphatic dicarboxylic acid having 6 to 12 carbon atoms (including the carbon of the carboxy group), such as adipic acid, azelaic acid, or sebacic acid.

The content of the aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms is preferably 5 to 100 mol % based on the total amount of the polyvalent carboxylic acid (A).
It is preferably 95 mol%, particularly preferably 30 to 90 mol%, further preferably 40 to 85 mol%, and particularly preferably 50 to 80 mol%. If the content is too low, the glass transition temperature of the polyester resin [I] becomes too high, and sufficient adhesive strength tends to be unavailable. If the content is too high, the adhesive strength at high temperatures tends to decrease, or the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance.

In the present invention, from the viewpoint of adhesive properties, it is also preferable to use asymmetric aromatic dicarboxylic acids (A-1) and aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms in combination as the polyvalent carboxylic acids (A). In that case, the content ratio (molar ratio) of the asymmetric aromatic dicarboxylic acids (A-1) to the aliphatic dicarboxylic acids (A-2) having 4 or more carbon atoms is (A-1)/(A
-2) is preferably 1/99 to 90/10, and particularly preferably 10/90 to 70
/30, and more preferably 20/80 to 60/40.

In the present invention, in order to increase the number of branching points in the polyester resin [I], trivalent or higher polyvalent carboxylic acids (A-3) can also be used. Among them, it is preferable to use trimellitic acids, since they are relatively unlikely to cause gelation during production.

The content of the trivalent or higher polyvalent carboxylic acid (A-3) is preferably 1:1 based on the total amount of the polyvalent carboxylic acid (A) in order to increase the cohesive strength when used as an adhesive.
The content is preferably 0 mol % or less, particularly preferably 0.1 to 5 mol %, and if the content is too high, gelation tends to occur during the production of the polyester resin [I].

[Polyol (B)]
The polyol (B) used as a constituent material of the polyester resin [I] includes dihydric alcohols and trihydric or higher polyols.

Examples of the dihydric alcohol include 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, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,
Aliphatic diols such as 5-pentanediol and 2,2,4-trimethyl-1,6-hexanediol;
1,2-Cyclohexanedimethanol, 1,3-Cyclohexanedimethanol, 1,4
Alicyclic diols such as cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol;
Examples of the aromatic diols include 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and ethylene oxide adducts and propylene oxide adducts thereof.
Further examples include fatty acid esters derived from castor oil, dimer diols derived from oleic acid, erucic acid, and the like, and glycerol monostearate.
Examples of the trivalent or higher polyols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,3,6-hexanetriol, and adamantanetriol.
The above polyols (B) may be used alone or in combination of two or more kinds.

In the present invention, in order to lower the glass transition temperature (Tg) of the polyester resin [I] and improve the initial adhesive strength, it is preferable that the polyol (B) contains an aliphatic diol (B-1) having a linear structure, more preferably an aliphatic diol having a linear structure having 2 to 18 carbon atoms, and particularly preferably ethylene glycol, 1,3-propanediol, 1,4-
Butanediol.

The content of the linear aliphatic diol (B-1) relative to the total polyol (B) is 1:1.
It is preferably from 1 to 100 mol %, more preferably from 2 to 80 mol %, and particularly preferably from 3 to 70 mol %.
%, more preferably 4 to 60 mol %, and particularly preferably 5 to 50 mol %. If the content is too low, it tends to be difficult to obtain a stable resin formation.

Among the polyols (B), it is preferable to contain a diol (B-2) having a hydrocarbon group in the side chain, because it can break down the crystallinity. Examples of the diol (B-2) having a hydrocarbon group in the side chain include dipropylene glycol, 2,4-
Dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-
Methyl-2-ethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,
Examples of the diol include aliphatic diols having a branched structure, such as 6-hexanediol and dimer diol.

The content of the diol (B-2) having a hydrocarbon group in the side chain is preferably 5 to 100 mol %, particularly preferably 20 to 90 mol %, and further preferably 40 to 50 mol %, based on the total amount of the polyol (B).
The content is preferably 0 to 80 mol %. If the content is too low, the resin tends to crystallize and it is difficult to obtain sufficient adhesive performance. If the content is too high, the reaction time in the production of the polyester resin [I] tends to be long.

Among the polyols (B), it is preferable to contain a diol (B-3) having an alicyclic structure, since it can break down the crystallinity and increase the elastic modulus. Examples of the diol (B-3) having an alicyclic structure include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, 2,2,4,
Examples of the diol include alicyclic diols such as 4-tetramethyl-1,3-cyclobutanediol.
Among these, 1,4-cyclohexanedimethanol is preferred from the viewpoint of reactivity.

The content of the diol (B-3) having an alicyclic structure is preferably 20 to 100 mol %, particularly preferably 40 to 98 mol %, and further preferably 60 to 98 mol %, based on the total amount of the polyol (B).
It is preferably 5 mol%. If the content is too small, the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance, and the elastic modulus tends to decrease, resulting in a decrease in impact resistance. If the content is too large, the reaction time tends to be longer in the production of the polyester resin [I].

Furthermore, in the present invention, a polyol having a valence of 3 or more is preferably used as the polyol (B) in order to form a reactive site with the crosslinking agent (IV) described later in the polyester resin (I) and to increase the cohesive strength.
B-4) is preferably used, and among them, trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,
It is preferable to use 5-pentanetriol or 1,2,6-hexanetriol, and among these, it is particularly preferable to use trimethylolpropane, which is less likely to cause gelation.

The content of the trihydric or higher polyol (B-4) is preferably 20 mol % or less, more preferably 0.1 to 10 mol %, and particularly preferably 0.5 to 5 mol %, based on the total content of the polyol (B). If the content of the trihydric or higher polyol is too high, the production of the polyester resin [I] tends to become difficult.

The polyester resin [I] used in the present invention is produced by appropriately selecting the above-mentioned polyvalent carboxylic acids (A) and polyol (B) and subjecting them to a polycondensation reaction in the presence of a catalyst by a known method.

The mixing ratio of the polyvalent carboxylic acid (A) and the polyol (B) is preferably 1 to 2 equivalents, particularly preferably 1.1 to 1.7 equivalents, of the polyol (B) per equivalent of the polyvalent carboxylic acid (A). If the mixing ratio of the polyol (B) is too low, the acid value tends to be high, making it difficult to increase the molecular weight, and if it is too high, the yield tends to decrease.

During the polycondensation reaction, an esterification reaction is carried out first, followed by a polycondensation reaction.

In such an esterification reaction, a catalyst is usually used, and specific examples thereof include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the perspective of the balance between high catalytic activity and hue, and germanium dioxide is particularly preferred.

The amount of the catalyst is preferably 1 to 10,000 ppm, more preferably 10 to 5,000 ppm, and even more preferably 20 to 3,000 ppm, based on the weight of all copolymerization components.
If the blending amount is too small, the polymerization reaction tends not to proceed sufficiently, whereas if the blending amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

The reaction temperature during the esterification reaction is preferably 200 to 300° C., particularly preferably 210 to 280° C., and further preferably 220 to 260° C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, whereas if the reaction temperature is too high, side reactions such as decomposition tend to occur easily. The pressure during the reaction is usually normal pressure.

After the esterification reaction, a polycondensation reaction is carried out.
The reaction conditions for the polycondensation reaction are as follows:
The reaction temperature is preferably 220 to 280° C., particularly preferably 23
It is preferable to carry out the reaction at 0 to 270° C., gradually reducing the pressure of the reaction system to 5 hPa or less in the end. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, whereas if the reaction temperature is too high, side reactions such as decomposition tend to occur easily.

Thus, the polyester resin [I] used in the present invention is obtained.

The polyester resin [I] usually has a structural unit derived from a polyvalent carboxylic acid (A) and a structural unit derived from a polyol (B), but when the structural unit derived from the aromatic polyvalent carboxylic acid, particularly the asymmetric aromatic dicarboxylic acid (A-1), is included as a structural unit derived from the polyvalent carboxylic acid (A), the structural unit derived from the asymmetric aromatic dicarboxylic acid (A-1) is preferably 1 to 90 mol% of the structural unit derived from the polyvalent carboxylic acid (A), particularly preferably 5 to 80 mol%, more preferably 10 to 70 mol%, even more preferably 15 to 60 mol%, and especially preferably 20 to 50 mol%. If the content is too low, the adhesive strength at high temperatures tends to decrease or the resin crystallizes, making it difficult to obtain sufficient adhesive performance, and if the content is too high, the initial adhesive strength (tack) tends to decrease.

In the case where the structural unit derived from the aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms is contained as a structural unit derived from the polyvalent carboxylic acid (A), the structural unit derived from the aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms is 5 to 100 times the structural unit derived from the polyvalent carboxylic acid (A).
% by mole, more preferably 20 to 95 mol %, and even more preferably 30
It is preferably up to 90 mol%, more preferably 40 to 85 mol%, and even more preferably 50 to 80 mol%. If the content is too low, the glass transition temperature of the polyester resin [I] becomes too high, and sufficient adhesive strength tends to be unavailable. If the content is too high, the adhesive strength at high temperatures tends to decrease, or the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance.

The structural unit derived from the trivalent or higher polyvalent carboxylic acid (A-3) is
In the case where the structural units derived from the polyvalent carboxylic acids (A-3) having a valence of three or more are contained as structural units derived from the polyvalent carboxylic acids (A), the structural units derived from the polyvalent carboxylic acids (A) are preferably 10 mol % or less, more preferably 0.1 to 5 mol %. If the content is too high, gelation tends to occur during the production of the polyester resin [I].

The structural unit derived from the linear aliphatic diol (B-1) is preferably a polyol (B
In the case where the structural units derived from the polyol (B) are contained, the structural units derived from the linear aliphatic polyol (B-1) preferably account for 1 to 100 mol % of the structural units derived from the polyol (B),
More preferably, it is from 2 to 80 mol %, further preferably from 3 to 70 mol %, and particularly preferably from 4 to
60 mol%, particularly preferably 5 to 50 mol%. If the content is too low, the reactivity of the polyester resin [I] during production tends to decrease. If the content is too high, the polyester resin [I] tends to crystallize, and the initial adhesive strength of the adhesive tends to decrease.

On the other hand, when the structural unit derived from the diol (B-2) having a hydrocarbon group on the side chain is contained as a structural unit derived from the polyol (B),
The structural units derived from polyol (B) preferably account for 5 to 100 mol %, particularly 20 to 90 mol %, and even more preferably 40 to 80 mol % of the structural units derived from polyol (B). If the content is too low, the polyester resin [I] tends to crystallize, and the initial adhesive strength of the adhesive tends to decrease. If the content is too high, the polyester resin [I] tends to crystallize, and the initial adhesive strength of the adhesive tends to decrease.
] tends to decrease in reactivity during production.

Furthermore, the structural unit derived from the diol (B-3) having an alicyclic structure is
When the structural unit derived from the diol (B-3) having an alicyclic structure is contained as a structural unit derived from the polyol (B), the structural unit derived from the diol (B-3) having an alicyclic structure preferably accounts for 20 to 100 mol %, particularly 40 to 98 mol %, and further preferably 60 to 95 mol % of the structural unit derived from the polyol (B). If the content is too low, the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance, and the elastic modulus tends to decrease, resulting in a decrease in impact resistance. If the content is too high, the reaction time tends to be longer in the production of the polyester resin [I].

In addition, in the case where the structural unit derived from the trihydric or higher polyol (B-4) is contained as a structural unit derived from the polyol (B), the structural unit derived from the trihydric or higher polyol (B-4) is
The content of the structural units derived from the polyol (B) is preferably 10 mol % or less, more preferably 0.1 to 5 mol %. If the content is too high, the polyester resin [I] tends to gel during production, making production difficult.

Here, the ratio of structural units (composition ratio) derived from each component of the polyester resin [I] is as follows:
For example, it can be determined by NMR.

The glass transition temperature (Tg) of the polyester resin [I] is −70° C. from the viewpoint of adhesive properties.
The glass transition temperature (Tg) is up to 20° C., preferably −60 to 10° C., more preferably −50 to 0° C., particularly preferably −40 to −5° C., and especially preferably −30 to −10° C. If the glass transition temperature (Tg) is too high, flexibility is lost, the initial adhesive strength decreases, and the adhesive strength is difficult to exert with pressure of the order of finger pressure, tending to decrease workability, whereas if the glass transition temperature (Tg) is too low, the cohesive strength decreases, the adhesive sheet becomes easily deformed, and the appearance tends to be impaired.

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

The weight average molecular weight of the polyester resin [I] is 5 or less from the viewpoint of the cohesive strength of the adhesive.
The weight average molecular weight is preferably 8,000 to 200,000, particularly preferably 10,000 to 150,000, and even more preferably 20,000 to 100,000. If the weight average molecular weight is too small, the adhesive will not have sufficient cohesive strength, and the heat resistance and mechanical strength will tend to decrease. If the weight average molecular weight is too large, the polyester resin [I] will tend to gel during production, making it difficult to obtain the resin, and the adhesion to the substrate will tend to decrease.

The weight average molecular weight in the present invention is a weight average molecular weight calculated in terms of the molecular weight of standard polystyrene, and is measured by a high performance liquid chromatograph ("ACQUITY APC" manufactured by Waters Corporation).
The column was ACQUITY APC XT 450, and the column was ACQUITY
One ACQUITY APC XT 200 and two ACQUITY APC XT 45, for a total of four
It is measured by using two books in series.

The acid value of the polyester resin [I] is preferably 10 mgKOH/g or less, particularly preferably 3 mgKOH/g or less, and further preferably 1 mgKOH/g or less.
If the acid value is too high, hydrolysis tends to proceed easily, and when a layer of metal or the like is attached to one side of the pressure-sensitive adhesive layer, corrosion tends to occur. For example, when a metal oxide thin film layer is formed, corrosion tends to occur, and the conductivity of the metal oxide thin film tends to decrease.

Here, the acid value of the polyester resin [I] is determined by neutralization titration based on JIS K0070.

<Ultraviolet absorber [II]>
The pressure-sensitive adhesive composition of the present invention comprises the above-mentioned polyester resin [I] and a specific ultraviolet absorber [II].
By containing the polyester resin [I] and the specific ultraviolet absorber [II], the pressure-sensitive adhesive composition of the present invention exhibits the effects of being excellent in adhesive strength and adhesion to substrates, being less prone to yellowing, and being excellent in ultraviolet absorbing ability.
In the case of an acrylic resin generally used as a pressure-sensitive adhesive composition, even if the acrylic pressure-sensitive adhesive composition contains the above-mentioned specific ultraviolet absorber [II], not all of the above-mentioned effects are obtained. The present invention has found that the above-mentioned effects, particularly excellent effects in yellowing resistance and ultraviolet absorbing ability, can be obtained when a polyester resin is selectively combined with the above-mentioned specific ultraviolet absorber.

It is important that the ultraviolet absorber [II] used in the present invention has a hydroxyl value of 900 mgKOH/g or less. It is preferably 800 mgKOH/g or less, and particularly preferably 600 mgKOH/g or less.
The hydroxyl value of the ultraviolet absorber [II] is preferably not more than 400 mgKOH/g, more preferably not more than 300 mgKOH/g, and particularly preferably not more than 200 mgKOH/g. If the hydroxyl value of the ultraviolet absorber [II] is too large, the yellowing resistance decreases.
The hydroxyl value can be calculated, for example, from the following formula.
Hydroxyl value = 56.1 x 1000 x number of hydroxyl groups per molecule / number average molecular weight

The ultraviolet absorber [II] used in the present invention preferably has a hydroxyl equivalent of 65 or more, more preferably from 100 to 1,000, particularly preferably from 200 to 800, and further preferably from 300 to 700. If the hydroxyl equivalent of the ultraviolet absorber [II] is too small, the yellowing resistance tends to decrease.

The above-mentioned hydroxyl group equivalent means the molecular weight per one hydroxyl group, and can be calculated, for example, by the following formula.
Hydroxyl equivalent = number average molecular weight/number of hydroxyl groups in one molecule

The number average molecular weight of the ultraviolet absorber [II] is preferably 180 to 1500, more preferably 250 to 1000, and particularly preferably 300 to 800. If the number average molecular weight of the ultraviolet absorber [II] is too small, the yellowing resistance tends to decrease, whereas if the number average molecular weight is too large, the adhesive strength tends to decrease.

The ultraviolet absorber [II] preferably has a maximum absorption wavelength of 300 to 395 nm, more preferably 320 to 390 nm, particularly preferably 330 to 380 nm, and particularly preferably 340 to 370 nm. Ultraviolet absorber [II]
If the maximum absorption wavelength is too short, the ultraviolet absorbing performance in the long wavelength region tends to decrease, whereas if the maximum absorption wavelength is too long, the yellowing resistance tends to decrease.

The ultraviolet absorber [II] is preferably at least one selected from the group consisting of triazine-based compounds, triazole-based compounds, cyanoacrylate-based compounds, and benzophenone-based compounds, more preferably triazine-based compounds, triazole-based compounds, and benzophenone-based compounds, and particularly preferably triazine-based compounds and triazole-based compounds.

Examples of the triazine compounds include 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-ethoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-propoxyphenyl)-4,6-diphenyl-1,3,5-triazine, and 2-(
2-(2-hydroxy-4-butoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-1,
3,5-Triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-
Diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-benzyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1
,3-5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3
-methylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-
1,3,5-triazine, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-
1,3,5-Triazine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)
-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-
Hydroxy-4-(3-octyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[
2-Hydroxy-4-(3-nonyloxy-2-hydroxypropyloxy)-5-α-
cumylphenyl]-s-triazine, 2,4-bis(2,4-dimethylphenyl)-6-
[2-hydroxy-4-(3-decyloxy-2-hydroxypropyloxy)-5-α
hydroxyphenyl triazines such as 2-(2-hydroxy-4-acryloyloxyethoxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, etc. These may be used alone or in combination of two or more. Among them, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5-triazine is preferred.

Commercially available triazine compounds include, for example, "Tinuvin" manufactured by BASF.
400", "Tinuvin405", "Tinuvin460", "Tinuvin4
77" and "Tinuvin 479".

The triazole-based compound is, for example, C7-C9-alkyl-3-[3-(2
H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl]propion ether, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)phenylbenzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-
(2-hydroxy-3,5-di-tert-amylphenyl)benzotriazole, 2-
(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-
hydroxy-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2,2'-methylenebis(4-cumyl-6-benzotriazolephenyl), 2,2'-p-phenylenebis(1,3-benzoxazin-4-one), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole, and the like. These may be used alone or in combination of two or more. Among them,
C7-C9-alkyl-3-[3-(2H-benzotriazol-2-yl)-5-(1
, 1-dimethylethyl)-4-hydroxyphenyl]propion ether is preferred.

Commercially available triazole compounds include, for example, "Tinuvi" manufactured by BASF.
nPS”, “Tinuvin99-2”, “Tinuvin326”, “Tinuvin
384-2”, “Tinuvin900”, “Tinuvin928”, “Tinuvi
n970" and "Tinuvin 1130".

Examples of the cyanoacrylate compounds include 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3,3-diphenylacrylate, octyl-2-cyano-3,3-diphenylacrylate, etc. These may be used alone or in combination of two or more kinds.

Commercially available cyanoacrylate compounds include, for example, "Uvi" manufactured by BASF Corporation.
Examples include "Uvinul3035", "Uvinul3039", and "Uvinul3030".
Examples of the benzophenone compounds include 2,2-dihydroxy-4,4-dimethoxybenzophenone and 2-hydroxy-4-octyloxybenzophenone.
Commercially available products of the benzophenone-based compounds include, for example, "Uvinu" manufactured by BASF Corporation.
l3049" and "Chimassorb81".

Among the above ultraviolet absorbents [II], at least one selected from the group consisting of triazine-based compounds and triazole-based compounds is preferred, since they have excellent adhesive strength, are less prone to yellowing, and have excellent ultraviolet absorbing ability.

The content of the ultraviolet absorber [II] is preferably 0.01 to 20 parts by weight, particularly preferably 0.1 to 10 parts by weight, and further preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the polyester resin (I). If the content of the ultraviolet absorber [II] is too high, the adhesive strength tends to decrease, whereas if the content is too low, the ultraviolet absorbing performance tends to decrease.

<Hydrolysis inhibitor [III]>
The pressure-sensitive adhesive composition of the present invention preferably further contains a hydrolysis inhibitor [III].
The hydrolysis inhibitor [III] is contained in order to ensure long-term durability.

The hydrolysis inhibitor [III] may be a conventionally known one, for example a compound that reacts with the carboxylic acid end group of the polyester resin [I] and bonds thereto, specifically, for example, a compound containing a functional group such as a carbodiimide group, an epoxy group, or an oxazoline group. The hydrolysis inhibitor [III] may be used alone or in combination of two or more kinds. Among them, a carbodiimide group-containing compound is preferred because it has a high effect of eliminating the catalytic activity of the proton derived from the carboxylic acid end group.

The carbodiimide group-containing compound is usually a compound having a carbodiimide group (-N=C=N-
However, in order to improve durability under high temperature and high humidity, it is preferable to use a compound having two or more carbodiimide groups in the molecule, that is, a polyvalent carbodiimide compound, and in particular, a compound having three or more, further five or more, and especially seven or more carbodiimide groups in the molecule. The number of carbodiimide groups contained in the above polyvalent carbodiimide compound in the molecule is usually 50 or less, and if there are too many carbodiimide groups, the molecular structure becomes too large, which tends to be undesirable.

As the carbodiimide group-containing compound, it is also preferable to use a high molecular weight polycarbodiimide produced by subjecting a diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimide catalyst.

Such high molecular weight polycarbodiimides may be synthesized or commercially available products may be used. When synthesizing high molecular weight polycarbodiimides, for example, those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction may be used.

Examples of such diisocyanates include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-
Examples of the isocyanate include dimethyl-4,4'-diphenylmethane diisocyanate, 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, 4,4'-dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more.

Furthermore, in terms of storage stability, the high molecular weight polycarbodiimide is preferably one in which the terminal isocyanate group is blocked with a blocking agent. Examples of the blocking agent include compounds having active hydrogen that reacts with the isocyanate group, or compounds having an isocyanate group. For example, monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates having one substituent selected from a carboxy group, an amino group, and an isocyanate group are included.

Examples of commercially available carbodiimide group-containing compounds include the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd., and among them, Carbodilite (registered trademark) "V-01", "V-02B", "V-03", "V-04K", and "V-04PF" are particularly well known.
"V-05", "V-07", "V-09" and "V-09GB" are preferred in that they have excellent compatibility with organic solvents.

The carbodiimide equivalent of the carbodiimide group-containing compound is preferably 50 to 100
00, particularly 100 to 1000, and further preferably 150 to 500.
The carbodiimide equivalent weight indicates the chemical formula weight per one carbodiimide group.

Examples of the epoxy group-containing compound used as the hydrolysis inhibitor [III] include glycidyl ester compounds, glycidyl ether compounds, etc. These can be used alone or in combination of two or more kinds.

Specific examples of the glycidyl ester compound include benzoic acid glycidyl ester,
t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexane carboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linoleic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, phthalic acid diglycidyl ester diglycidyl ester, diglycidyl naphthalene dicarboxylate, diglycidyl methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl cyclohexanedicarboxylate, diglycidyl adipic acid, diglycidyl succinate, diglycidyl sebacic acid, diglycidyl dodecanedicarboxylate, diglycidyl octadecanedicarboxylate, triglycidyl trimellitate, and tetraglycidyl pyromellitic acid. These may be used alone or in combination of two or more.

Specific examples of the glycidyl ether compound include, for example, phenyl glycidyl ether,
o-phenyl glycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ-epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane,
1-(β,γ-epoxypropoxy)-2-benzyloxyethane, 2,2-bis-[
Examples of the bisglycidyl polyether include bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane, 2,2-bis-(4-hydroxyphenyl)methane, and bisglycidyl polyethers obtained by reacting epichlorohydrin with bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane. These can be used alone or in combination of two or more kinds.

The oxazoline group-containing compound is preferably a bisoxazoline compound. Specifically, for example, 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2
-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'-
Bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-
butyl-2-oxazoline), 2,2'-bis(4-hexyl-2-oxazoline), 2
, 2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-
p-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-o-phenylenebis(2-oxazoline), 2,2'-p-phenylenebis(4-methyl-2-oxazoline), 2,2'-p-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4-dimethyl-2-oxazoline), 2
, 2'-ethylenebis(2-oxazoline), 2,2'-tetramethylenebis(2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethylenebis(2-oxazoline), 2,2'-decamethylenebis(2-oxazoline), 2,
2'-Ethylenebis(4-methyl-2-oxazoline), 2,2'-tetramethylenebis(
4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethane bis(
2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), 2,2'-
Examples of the 2-oxazoline include diphenylenebis(2-oxazoline).
, 2'-bis(2-oxazoline) is most preferred from the viewpoint of reactivity with the polyester resin (A). These may be used alone or in combination of two or more.

It is preferable that the hydrolysis inhibitor [III] has low volatility, and therefore it is preferable to use one having a high number average molecular weight.
Use one that is between 000 and 5000.
From the viewpoint of hydrolysis resistance, it is preferable to use a hydrolysis inhibitor [III] having a high weight-average molecular weight. The weight-average molecular weight of the hydrolysis inhibitor [III] is preferably 500 or more, more preferably 2000 or more, and even more preferably 3000 or more. The upper limit of the weight-average molecular weight is usually 50,000.
If the molecular weight of the hydrolysis inhibitor [III] is too small, the hydrolysis resistance tends to decrease, whereas if the molecular weight is too large, the compatibility with the polyester resin [I] tends to decrease.

The content of the hydrolysis inhibitor [III] is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, further preferably 0.3 to 3 parts by weight, and particularly preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the polyester resin [I]. If the content is too high, turbidity tends to occur due to poor compatibility with the polyester resin [I], while if the content is too low, sufficient durability tends to be difficult to obtain.

The content of the hydrolysis inhibitor [III] is preferably optimized depending on the acid value of the polyester resin [I]. The molar ratio [(b)/(a)] of the total number of moles (b) of functional groups of the hydrolysis inhibitor [III] in the polyester pressure-sensitive adhesive composition to the total number of moles (a) of acidic functional groups of the polyester resin in the polyester pressure-sensitive adhesive composition is preferably 0.5≦(b)/(a), and particularly preferably 1≦(b)/(a)≦
1000, and more preferably 1.5≦(b)/(a)≦100.
If the molar ratio of (b) to (a) is too low, the moist heat resistance tends to decrease. If the molar ratio of (b) to (a) is too high, the compatibility with the polyester resin [I] tends to decrease, and the adhesive strength, cohesive strength, and durability tend to decrease.

<Crosslinking agent [IV]>
Examples of the crosslinking agent [IV] include compounds having a functional group that reacts with at least one of the hydroxyl group and the carboxyl group contained in the polyester resin [I], such as polyisocyanate-based compounds and polyepoxy-based compounds. Among these, it is particularly preferable to use polyisocyanate-based compounds, since they can achieve a good balance between initial adhesive strength, mechanical strength, and heat resistance.

Examples of such polyisocyanate compounds include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, and triphenylmethane triisocyanate, and also include adducts of the above polyisocyanates with polyol compounds such as trimethylolpropane, and biuret and isocyanurate compounds of these polyisocyanate compounds. The above polyisocyanate compounds may also be used in which the isocyanate moiety is blocked with phenol, lactam, or the like. These crosslinking agents [IV] may be used alone or in combination of two or more.

The content of the crosslinking agent [IV] can be appropriately selected depending on the molecular weight of the polyester resin [I] and the intended use. Usually, the content of the reactive group contained in the crosslinking agent [IV] is 0.2 or less relative to 1 equivalent of at least one of the hydroxyl group and the carboxyl group contained in the polyester resin [I].
The crosslinking agent [IV] is preferably contained in an amount of 0.5 to 10 equivalents, and particularly preferably 0.5 to 10 equivalents.
The amount is preferably from 0.5 to 5 equivalents, and more preferably from 0.5 to 3 equivalents.
If the equivalent number of the reactive group contained in the crosslinking agent [IV] is too small, the cohesive strength tends to decrease, whereas if it is too large, the flexibility tends to decrease.

In the reaction between the polyester resin [I] and the crosslinking agent [IV],
and organic solvents not having a functional group that reacts with component [IV], for example, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, aromatics such as toluene and xylene, etc. These can be used alone or in combination of two or more kinds.

<Urethanization catalyst [V]>
The pressure-sensitive adhesive composition of the present invention preferably further contains a urethanization catalyst [V].
As the urethanization catalyst [V], for example, an organometallic compound, a tertiary amine compound, etc. can be used. These can be used alone or in combination of two or more kinds.

Examples of the organometallic compound include zirconium-based compounds, iron-based compounds, tin-based compounds, titanium-based compounds, lead-based compounds, cobalt-based compounds, and zinc-based compounds.
Examples of the zirconium compound include zirconium naphthenate and zirconium acetylacetonate.
Examples of iron-based compounds include iron acetylacetonate and iron 2-ethylhexanoate.
Examples of the tin compounds include dibutyltin dichloride, dibutyltin oxide, and dibutyltin dilaurate.
Examples of titanium compounds include dibutyltitanium dichloride, tetrabutyltitanium, and butoxytitanium trichloride.
Examples of lead-based compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate,
Examples include lead naphthenate.
Examples of the cobalt-based compounds include cobalt 2-ethylhexanoate and cobalt benzoate.
Examples of zinc compounds include zinc naphthenate and zinc 2-ethylhexanoate.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo-(5,4,0)-undecene-7.

Among these urethane-forming catalysts [V], in terms of reaction rate and pot life of the pressure-sensitive adhesive layer,
Organometallic compounds are preferred, zirconium compounds are particularly preferred, and zirconium acetylacetonate is particularly preferred.

[Catalyst inhibitors]
In the pressure-sensitive adhesive composition of the present invention, it is preferable to incorporate a catalytic action inhibitor into the urethanization catalyst [V] in order to extend the pot life and improve the coatability.
Examples of the catalytic inhibitor include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate; and β-ketoesters such as acetylacetone, 2,4-hexanedione, and benzoylacetone.
These are keto-enol tautomeric compounds that protect the urethanization catalyst [V], thereby reducing the catalytic activity of the urethanization catalyst [V] in a solution state, suppressing an excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition after blending, and enabling the pot life of the pressure-sensitive adhesive composition to be extended.
Among these, it is preferable to use acetylacetone as the catalyst inhibitor from the viewpoint of the balance between pot life and curing speed. These catalyst inhibitors may be used alone or in combination of two or more.

The blending ratio (weight ratio) of the catalytic inhibitor to the urethanization catalyst [V] is preferably in the range of catalytic inhibitor: urethanization catalyst [V] = 0.001:1 to 15:1, more preferably 0.005:1 to 13:1, and particularly preferably 0.01:1 to 10:1. If the content of the catalytic inhibitor is too low relative to the content of the urethanization catalyst [V], the pot life tends to be short and the coatability tends to be reduced, whereas if it is too high, the curing rate tends to be reduced.

<Silane coupling agents [VI]>
The pressure-sensitive adhesive composition of the present invention preferably further contains a silane coupling agent [VI].
Examples of the silane coupling agent [VI] include an amino group-containing silane coupling agent, an epoxy group-containing silane coupling agent, a vinyl group-containing silane coupling agent, a (meth)acryloyl group-containing silane coupling agent, a mercapto group-containing silane coupling agent,
These may be used alone or in combination.
More than one species may be used in combination.

Examples of the amino group-containing silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, and 3-phenylaminopropyltrimethoxysilane.

Examples of the epoxy group-containing silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

Examples of the vinyl group-containing silane coupling agent include vinyltriacetoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

Examples of the (meth)acryloyl group-containing silane coupling agent include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and
meth)acryloxypropyltriethoxysilane and the like.

Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptomethyldimethoxysilane, and 3-mercaptotriethoxysilane.

Examples of the isocyanate group-containing silane coupling agent include isocyanurate group-containing silane coupling agents such as tris-(trimethoxysilylpropyl)isocyanurate, 3-isocyanatepropyltriethoxysilane, and the like.

Among these silane coupling agents, epoxy group-containing silane coupling agents are preferred, with 3-glycidoxypropyltrimethoxysilane being particularly preferred.

The content of the silane coupling agent [VI] is usually 0.01 to 10 parts by weight, and preferably 0.02 to 5 parts by weight, based on 100 parts by weight of the polyester resin [I].
Particularly preferably, the amount is from 0.03 to 3 parts by weight, and further preferably, from 0.1 to 1 part by weight.
If the content of the silane coupling agent [VI] is too high, the adhesive strength tends to decrease, whereas if the content is too low, the adhesion to the substrate, etc. tends to decrease.

In the pressure-sensitive adhesive composition of the present invention, in addition to the above-mentioned polyester resin [I], ultraviolet absorber [II], hydrolysis inhibitor [III], crosslinking agent [IV], and the like, additives such as antioxidants such as hindered phenols, softeners, ultraviolet absorbers other than those mentioned above, stabilizers, antistatic agents, tackifiers, and other inorganic or organic fillers,
Additives in the form of powders or particles such as metal powders and pigments can be blended in. These can be used alone or in combination of two or more kinds.

In addition to the additives, the pressure-sensitive adhesive composition of the present invention may contain small amounts of impurities contained in the raw materials for producing the components of the pressure-sensitive adhesive composition.

Such a pressure-sensitive adhesive composition may be, for example, a mixture of the polyester resin [I] and an ultraviolet absorbing agent [
The polyester-based resin [I] can be obtained by mixing and dispersing the polyester-based resin [II] and, if necessary, optional components during the production of the polyester-based resin [I], or by mixing the polyester-based resin [I] in a solution prepared by dissolving the polyester-based resin [I] in an organic solvent and dispersing the mixture using a mixing roller.

The pressure-sensitive adhesive according to the present invention is made of the pressure-sensitive adhesive composition, that is, is obtained by crosslinking (curing) the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive.
The pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one or both sides of a supporting substrate, or may be a substrate-less double-sided pressure-sensitive adhesive sheet having no substrate. The pressure-sensitive adhesive sheet of the present invention is particularly suitable as a pressure-sensitive adhesive sheet for optical members used for bonding optical members.
In the present invention, the term "sheet" includes "film" and "tape".

<Adhesive sheet>
The pressure-sensitive adhesive sheet can be produced, for example, as follows.
Such a pressure-sensitive adhesive sheet can be produced according to a known method for producing a pressure-sensitive adhesive sheet. For example, the pressure-sensitive adhesive composition is applied to one surface of a substrate, followed by drying,
An adhesive layer is formed, a release sheet is attached to its surface (the surface opposite to the surface in contact with the substrate), and cured as necessary to obtain the adhesive sheet of the present invention having a substrate and an adhesive layer, the adhesive layer being provided on at least one surface of the substrate.

Alternatively, the pressure-sensitive adhesive composition is applied onto a release sheet, followed by drying to form a pressure-sensitive adhesive layer;
The pressure-sensitive adhesive sheet of the present invention can also be obtained by laminating a substrate to the surface (the surface opposite to the surface in contact with the release sheet) and curing the substrate as necessary.

Also, a pressure-sensitive adhesive layer is formed on a release sheet, and its surface (the surface opposite to the surface in contact with the release sheet)
By laminating the release sheet and another release sheet to the above, a substrate-less double-sided PSA sheet of a substrate-less type that does not have a substrate can be produced.

When using the resulting pressure-sensitive adhesive sheet or substrate-less double-sided pressure-sensitive adhesive sheet, the release sheet is peeled off from the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is attached to an adherend.

Examples of the substrate include polyethylene naphthate, polyethylene terephthalate,
Polyester resins such as polybutylene terephthalate and polyethylene terephthalate/isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene and polymethylpentene; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride and polyethylene fluoride; polyamides such as nylon 6 and nylon 6,6; polyvinyl chloride,
Vinyl polymers such as polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose-based resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; polyimide; synthetic resin sheets made of cycloolefin polymers, etc.;
Metal foil such as aluminum, copper, iron, etc.;
Paper such as fine paper and glassine paper;
Examples of the material include woven fabrics and nonwoven fabrics made of glass fibers, natural fibers, synthetic fibers, and the like.
These substrates can be used as a single layer or as a multi-layer structure in which two or more types are laminated.

Among these, substrates made of polyethylene terephthalate or polyimide are particularly preferred, with polyethylene terephthalate being particularly preferred because of its excellent adhesion to the adhesive. Furthermore, polyethylene terephthalate having a metal thin film layer is preferred because it has excellent adhesion between the substrate and the adhesive, can maintain the substrate stably without corroding the metal thin film layer, and can prominently exhibit the effects of the adhesive used in the present invention.

In the present invention, the ITO electrode film is formed as a thin film on a polyethylene terephthalate (PET) substrate, and the PET side of the film has an adhesive layer, and the PET is attached via the adhesive layer.
It is also preferable to form an optical laminate in which a substrate and a polycarbonate (PC) film are laminated, and an acrylic film is further laminated (layer structure: ITO electrode film/PET substrate/adhesive layer/PC film/acrylic film).

Examples of the release sheet include the various synthetic resin sheets, paper, cloth, etc., exemplified above as the base material.
Nonwoven fabrics that have been subjected to release treatment can be used. Among them, the following release sheets are available:
It is preferable to use a silicone-based release sheet.

The thickness of the substrate is, for example, preferably from 1 to 1000 μm, particularly preferably from 2 to 500 μm, and further preferably from 3 to 300 μm.

The pressure-sensitive adhesive composition may be applied using, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or the like.

As for the drying conditions after coating the pressure-sensitive adhesive composition, the drying temperature is preferably 60 to 140° C., and particularly preferably 80 to 120° C. The drying time is preferably 0.5 to 30 minutes, and particularly preferably 1 to 5 minutes.

The conditions for the curing treatment are usually room temperature (23°C) to 70°C, and the time is usually 1 to 3 hours.
0 days, specifically, for example, 1 to 20 days at 23° C., preferably 3 to 14 days at 23° C.
The incubation may be performed under conditions such as at 40° C. for 1 to 10 days.

The thickness of the adhesive layer of the above-mentioned pressure-sensitive adhesive sheet and the substrate-less double-sided pressure-sensitive adhesive sheet is 2 to 5
It is preferable that the thickness is 5 to 300 μm, particularly preferably 10 to 300 μm, and further preferably 10 to 300 μm.
The thickness is 200 μm or less. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease, and if the thickness is too thick, it becomes difficult to apply the pressure-sensitive adhesive layer uniformly and air bubbles tend to be trapped in the coating film. When considering impact absorption, the thickness is preferably 50 μm or more.

The thickness of the adhesive layer was measured using a Digimatic Indicator (ID-C1, manufactured by Mitutoyo Corporation).
12B) and subtracting the measured thickness of the constituent members other than the pressure-sensitive adhesive layer from the measured thickness of the entire pressure-sensitive adhesive sheet.

The gel fraction of the pressure-sensitive adhesive layer is preferably 10% by weight or more from the viewpoints of durability and adhesive strength, particularly preferably 15 to 80% by weight, and further preferably 20 to 70% by weight. If the gel fraction is too low, the cohesive strength decreases, and durability tends to decrease.
If the gel fraction is too high, there is a concern that the adhesive strength will decrease due to an increase in cohesive strength.

The gel fraction is an indication of the degree of crosslinking, and is calculated, for example, by the following method. That is, an adhesive sheet (without a separator) consisting of an adhesive layer formed on a polymer sheet (e.g., a PET film, etc.) serving as a substrate is wrapped in a 200-mesh SUS wire netting, and immersed in toluene at 23°C for 24 hours, and the weight percentage of the insoluble adhesive component remaining in the wire netting after immersion relative to the weight of the adhesive component before immersion is taken as the gel fraction, with the weight of the substrate being subtracted.

Furthermore, such a pressure-sensitive adhesive sheet may be provided with a release sheet on the outer side of the pressure-sensitive adhesive layer, if necessary, to protect the pressure-sensitive adhesive layer. In a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on one side of a substrate, a release treatment may be applied to the side of the substrate opposite to the pressure-sensitive adhesive layer, so that the release-treated surface can be used to protect the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive of the present invention can be used for bonding various members, and is preferably used as a pressure-sensitive adhesive for optical members for bonding optical members. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition can be laminated on an optical member to obtain the above-mentioned optical member with the pressure-sensitive adhesive layer.

Examples of such optical members include transparent electrode films such as ITO electrode films and inorganic or organic conductive films such as polythiophene, polarizing plates, retardation plates, elliptical polarizing plates, optical compensation films, brightness enhancement films,
Examples of the film include an electromagnetic wave shielding film, a near infrared absorbing film, and an AR (anti-reflection) film. Among these, an ITO electrode film is preferable because it is effective when the optical member is a transparent electrode film and can obtain high adhesive strength, and is particularly preferable. In addition, an ITO electrode film is often formed as a thin film on a substrate such as glass or PET, but in the present invention, as already mentioned, it is particularly preferable to use a film in which an ITO electrode film is formed as a thin film on a PET substrate.
The film is also suitable for use as a light extraction film provided on the light emitting surface of a surface emitter of an organic EL element, or as a light diffusion sheet for a liquid crystal display.

It is preferable that the optical member with the pressure-sensitive adhesive layer further has a release film on the surface of the pressure-sensitive adhesive layer opposite to the optical member surface, and when the optical member is put into practical use, the release film is peeled off and the pressure-sensitive adhesive layer is attached to an adherend. As the release film, it is preferable to use a silicone-based release film.

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention. In the examples, "parts" and "%" denote the percentages of the parts and percentages.
Weight basis is meant.
In addition, regarding the glass transition temperature of the polyester resin [I] in the following examples,
The measurements were carried out according to the method described above.

Prior to the examples, the following ingredients were prepared:

<Production of polyester resin [I]>
The mol % of each component of the polybasic carboxylic acid (A) described in the following Production Examples indicates a molar ratio when the total amount of the polybasic carboxylic acid (A) is taken as 100 mol %.
The mol % of each component of polyol (B) described in the following Production Examples indicates a molar ratio when the total amount of polyol (B) is taken as 100 mol %.

[Production of polyester resin [I-1]]
A reactor equipped with a heater, thermometer, stirrer, distillation column, nitrogen inlet tube, and vacuum device.
Polyvalent carboxylic acids (A) of 76.6 parts of isophthalic acid, 186.5 parts of sebacic acid, 173.6 parts of azelaic acid, polyols (B) of 14.3 parts of ethylene glycol and 349 parts of cyclohexanedimethanol, and 0.04 parts of germanium dioxide as a catalyst were charged.
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 a polycondensation reaction was carried out for 3 hours to produce a polyester resin [I-1].
The resulting polyester resin [I-1] had a glass transition temperature of −25° C. and a weight average molecular weight of 60000. The final component ratio was isophthalic acid/sebacic acid/azelaic acid=20 mol %/40 mol %/40 mol % as the polyvalent carboxylic acid (A), and ethylene glycol/cyclohexanedimethanol=8 mol %/92 mol % as the polyol (B).

[Ultraviolet absorber]
[II-1]: Triazine-based ultraviolet absorber (manufactured by BASF, "Tinuvin 460", hydroxyl value 178 mg KOH/g, hydroxyl equivalent 315, number average molecular weight 630, maximum absorption wavelength 3
49 nm)
[II-2]: Triazole-based UV absorber (manufactured by BASF, "Tinuvin 384-2
", hydroxyl value 124 KOH/g, hydroxyl equivalent 451.6, number average molecular weight 451.6, maximum absorption wavelength 345 nm)
[II'-1]: Benzophenone-based ultraviolet absorber (manufactured by BASF, "Uvinul 3050
", hydroxyl value 912 KOH/g, hydroxyl equivalent 61.5, number average molecular weight 246, maximum absorption wavelength 346 nm)

[Hydrolysis inhibitor [III]]
[III-1]: Aromatic polycarbodiimide compound in which the isocyanate terminal is substituted with a substituent derived from polyethylene glycol monomethyl ether (manufactured by Nisshinbo Chemical Inc., "Carbodilite V-04PF")

[Crosslinking agent [IV]]
[IV-1]: Trimethylolpropane/tolylene diisocyanate adduct (manufactured by Tosoh Corporation,
"Coronate L55E")

[Urethanization catalyst [V]]
[V-1]: Zirconium-based compound diluted with acetylacetone to a solid content of 1% (manufactured by Matsumoto Fine Chemical Co., Ltd., "Orgatics ZC-150")

[Silane coupling agents [VI]]
[VI-1]: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicones, "K
BM-403"

Example 1
The polyester resin [I-1] obtained above was diluted with toluene to a solids concentration of 50%, and to this polyester resin [I-1] solution (100 parts as solids), 3 parts of ultraviolet absorber [II-1], 1.5 parts of hydrolysis inhibitor [III-1], and 2.
25 parts (solid content), 0.02 parts (solid content) of a urethane catalyst [V-1], and 0.1 parts of a silane coupling agent [VI-1] were blended and stirred to obtain a pressure-sensitive adhesive composition.

Example 2
In Example 1, except that 3 parts of the ultraviolet absorber [II-1] was changed to 4 parts of [II-2],
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1.

(Comparative Example 1)
An adhesive composition was obtained in the same manner as in Example 1, except that 3 parts of the ultraviolet absorber [II-1] was changed to 1.5 parts of [II'-1].

(Comparative Example 2)
The acrylic resin [I'] solution (100 parts as solid content) obtained as described below was mixed with 4 parts of ultraviolet absorber [II-2], 0.4 parts (solid content) of crosslinking agent [IV-1], and 0.1 parts of silane coupling agent [VI-1], and stirred and mixed to obtain a pressure-sensitive adhesive composition.
[Production of acrylic resin [I']]
Into a four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 38.8 parts of butyl acrylate, 60 parts of methyl acrylate, 1.0 part of hydroxyethyl methacrylate, 0.2 parts of 2-(dimethylamino)ethyl acrylate, 60 parts of ethyl acetate, and 8 parts of methyl ethyl ketone were charged, and after heating to reflux was started, 0.5 parts of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the mixture was reacted at the ethyl acetate reflux temperature for 7 hours. The mixture was then diluted with 98 parts of ethyl acetate and 20 parts of methyl ethyl ketone to obtain acrylic resin [I'].
A solution was prepared.
The glass transition temperature of the obtained acrylic resin [I'] was -21°C and the weight average molecular weight was 53.
The number was 0000.

(Comparative Example 3)
A pressure-sensitive adhesive composition was obtained in the same manner as in Comparative Example 2, except that 4 parts of the ultraviolet absorber [II-2] was changed to 1.5 parts of [II'-1].

The resulting pressure-sensitive adhesive composition was evaluated as follows, and the results are shown in Table 1 below.

<Production of substrate-less double-sided adhesive sheet>
The pressure-sensitive adhesive compositions obtained in the Examples and Comparative Examples were applied onto a 100 μm-thick PET release film (Mitsui Chemicals Tocello, SP-PET-03-BU) (Fα) using an applicator and dried at 100° C. for 4 minutes to obtain pressure-sensitive adhesive sheets with a release film having a pressure-sensitive adhesive layer thickness of 50 μm.
Next, the surface of the adhesive layer of the obtained adhesive sheet with a release film is coated with the release film (F
α) is a PET release film (manufactured by Mitsui Chemicals Tocello, S
P-PET-01-BU) (Fβ) and subjected to aging treatment at 40° C. for 7 days to obtain a substrate-less double-sided PSA sheet.

<Adhesive sheet evaluation>
[Adhesive strength]
The release film (Fβ) on one side of the substrate-less double-sided pressure-sensitive adhesive sheet obtained above was peeled off, and the pressure-sensitive adhesive layer was transferred to a PET film (100 μm) to prepare a pressure-sensitive adhesive sheet for evaluation.
The obtained pressure-sensitive adhesive sheet for evaluation was cut to a width of 10 mm, the separator on the other side was peeled off, and the exposed pressure-sensitive adhesive layer was attached to a non-alkali glass plate (manufactured by Corning Incorporated, Eagle XG) and then pressure-bonded by autoclaving (50°C, 0.5 MPa, 20 minutes) to produce a test specimen having a configuration of PET film/pressure-sensitive adhesive layer/non-alkali glass plate.
The above test pieces were subjected to a tensile test using a thermostatic chamber equipped tensile tester (Shimadzu Corporation, Autograph AG-X
50N) at 23°C x 50% RH, peel speed 60 mm/min, 180
The peel strength was measured and evaluated according to the following criteria. The results are shown in Table 1.
(Evaluation Criteria)
○: Greater than 5N/10mm △: Greater than 3N/10mm and 5N/10mm or less ×: 3N/10mm or less

[Adhesion to substrate]
The release film (Fβ) on one side of the substrate-less double-sided pressure-sensitive adhesive sheet obtained above was peeled off, and the pressure-sensitive adhesive layer was transferred to a PET film (100 μm) to prepare a pressure-sensitive adhesive sheet for evaluation.
The obtained pressure-sensitive adhesive sheet for evaluation was cut to a width of 10 mm, the separator on the other side was peeled off, and the exposed pressure-sensitive adhesive layer was attached to a non-alkali glass plate (manufactured by Corning Incorporated, Eagle XG) and then pressure-bonded by autoclaving (50°C, 0.5 MPa, 20 minutes) to produce a test specimen having a configuration of PET film/pressure-sensitive adhesive layer/non-alkali glass plate.
The above test pieces were subjected to a tensile test using a thermostatic chamber equipped tensile tester (Shimadzu Corporation, Autograph AG-X
50N) at 23°C x 50% RH, peel speed 60 mm/min, 180
The peeling mode in measuring the peel strength was evaluated according to the following criteria. The results are shown in Table 1.
(Evaluation Criteria)
○: Peeling at the interface of the adherend ×: Peeling at the interface of the substrate or cohesive failure

[Yellowing resistance]
The release film (Fβ) on one side was peeled off from the substrate-less double-sided pressure-sensitive adhesive sheet obtained above, the pressure-sensitive adhesive layer was transferred to an alkali-free glass plate (Corning, Eagle XG), and the release film (Fα) on the other side was peeled off to prepare a test piece having a pressure-sensitive adhesive layer/alkali-free glass configuration. The b ^* value of the obtained test piece was measured using a color difference meter (Nippon Denshoku Industries, SE6000) and evaluated according to the following criteria. The results are also shown in Table 1.
(Evaluation Criteria)
○: 2 or less ×: greater than 2

[UV absorption ability]
The release film (Fβ) on one side was peeled off from the substrate-less double-sided pressure-sensitive adhesive sheet obtained above, the pressure-sensitive adhesive layer was transferred to an alkali-free glass plate (Corning, Eagle XG), and the release film (Fα) on the other side was peeled off to prepare a test piece having a pressure-sensitive adhesive layer/alkali-free glass structure. The obtained test piece was measured using an ultraviolet-visible-near infrared spectrophotometer (JASCO, V
The ultraviolet light transmittance (%) at 380 nm was measured using a spectrometer (F1-7200) and evaluated according to the following criteria. The results are also shown in Table 1.
(Evaluation Criteria)
○: 5% or less △: 5% to 10% ×: more than 10%

The results in Table 1 above show that the pressure-sensitive adhesive compositions of Examples 1 and 2 are excellent in adhesive strength and adhesion to substrates, while also exhibiting little yellowing and excellent ultraviolet absorbing ability.
In contrast, the pressure-sensitive adhesive composition of Comparative Example 1 had adhesive strength, adhesion to substrates, and ultraviolet absorbing ability, but yellowing was observed, and the performance as a pressure-sensitive adhesive for optical members was inferior.
In Comparative Examples 2 and 3, which used acrylic resins, the adhesion to the substrate was poor, but the adhesive strength, yellowing resistance, and ultraviolet absorbing ability were not significantly different depending on the type of ultraviolet absorber. This also shows that the combination of a polyester resin with an ultraviolet absorber is very important in a pressure-sensitive adhesive composition containing a polyester resin.

The pressure-sensitive adhesive composition of the present invention has excellent adhesive strength and adhesion to substrates, while also exhibiting little yellowing and excellent ultraviolet absorption ability. Therefore, pressure-sensitive adhesives and pressure-sensitive adhesive sheets using the composition can be suitably used for bonding optical components in displays and optical components such as optical films and substrates that constitute such displays.

Claims (13)

A polyester-based pressure-sensitive adhesive composition comprising a polyester-based resin [I] containing structural units derived from a polyvalent carboxylic acid (A) and structural units derived from a polyol (B) (excluding polyester-based resins having a glass transition temperature in the range of -80 to 0°C and having a hydroxyl group and/or a carboxyl group in the side chain) , and an ultraviolet absorber [II], wherein the polyester-based resin [I] contains structural units derived from an aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms as structural units derived from the polyvalent carboxylic acid (A), the content of the structural units derived from the aliphatic dicarboxylic acid (A-2) having 4 or more carbon atoms being 40 to 100 mol % of the structural units derived from the polyvalent carboxylic acid (A), and the ultraviolet absorber [II] is an ultraviolet absorber having a hydroxyl value of 900 mgKOH/g or less. The polyester-based adhesive composition according to claim 1, characterized in that the glass transition temperature (Tg) of the polyester-based resin [I] is -70 to 20°C. The polyester-based adhesive composition according to claim 1 or 2, characterized in that the number average molecular weight of the ultraviolet absorber [II] is 180 to 1500. The polyester-based adhesive composition according to any one of claims 1 to 3, characterized in that the ultraviolet absorber [II] has a maximum absorption wavelength of 300 to 395 nm. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 4, characterized in that the ultraviolet absorber [II] is at least one selected from the group consisting of triazine-based compounds and triazole-based compounds. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising a hydrolysis inhibitor [III]. The polyester-based pressure-sensitive adhesive composition according to any one of claims 1 to 6, further comprising a crosslinking agent [IV]. An adhesive characterized by being formed by crosslinking the polyester-based adhesive composition according to any one of claims 1 to 7. An adhesive sheet having an adhesive layer containing the adhesive according to claim 8. The adhesive sheet according to claim 9, characterized in that it has a substrate and an adhesive layer, and the adhesive layer is provided on at least one side of the substrate. The adhesive sheet according to claim 9, characterized in that the adhesive sheet is a substrateless type that does not have a substrate. The pressure-sensitive adhesive sheet according to any one of claims 9 to 11, characterized in that it is used for bonding optical members. An optical member with an adhesive layer, comprising an adhesive layer and an optical member, characterized in that the adhesive layer contains the adhesive according to claim 8.