JP2018172662A - Polyester-based adhesive, adhesive sheet for optical member and polyester-based adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester-based adhesive having excellent adhesiveness to an adherend, especially a polycarbonate base material and having a high refractive index, to provide an adhesive sheet for an optical member and to provide a polyester-based adhesive composition.SOLUTION: A polyester-based adhesive, which is composed of [I] an adhesive composition containing (A) a polyester-based resin, has an adhesive strength (α) as given below of 10 N/25 mm or more and a refractive index of 1.530 or more. The adhesive strength (α): when a polyester-based adhesive is formed on a base material into an adhesive sheet, 180 degree peeling strength (N/25 mm) at a peeling speed of 300 mm per minute for an adherend in a measurement after the lapse of 24 hours after attaching the adhesive sheet to an adherend of a polycarbonate plate and subjecting the same to autoclave treatment at 50°C and 0.5 MPa for 20 minutes.SELECTED DRAWING: None

Description

  The present invention relates to a polyester-based pressure-sensitive adhesive, and more specifically, a polyester-based pressure-sensitive adhesive having a high refractive index and excellent adhesion to various adherends, particularly a polycarbonate material, and further, a pressure-sensitive adhesive sheet for an optical member, Moreover, it is related with the polyester-type adhesive composition for obtaining these.

  Conventionally, polyester resins have excellent heat resistance, chemical resistance, durability, and mechanical strength, so they are used in a wide range of applications such as films, PET bottles, fibers, toners, electrical parts, and adhesives and adhesives. It has been.

  In recent years, a display device such as a liquid crystal display (LCD) and an input device used in combination with the display device such as a touch panel have come to be widely used. A transparent adhesive sheet is used for bonding optical members such as films and substrates.

  Further, a light diffusion sheet is used to increase the visibility of the liquid crystal display device. The light diffusion sheet is made of a transparent resin material and a filler, and develops diffusibility by utilizing a difference in refractive index between the resin material and the filler. And although the optical member of a liquid crystal display device is integrated in a liquid crystal display device using an adhesive, it is desired that the refractive index of an adhesive layer is higher for light diffusibility. In general, since the refractive index of the optical film is higher than that of the pressure-sensitive adhesive, there is a problem that reflection occurs at the interface and the light extraction property of the display device is lowered. Thus, since the interface reflection is lowered, it is desired that the refractive index of the pressure-sensitive adhesive is higher in terms of light extraction efficiency.

An acrylic resin pressure-sensitive adhesive is generally used for bonding the optical members as described above, but in this case, the refractive index of the pressure-sensitive adhesive layer is around 1.47, which exceeds 1.50. It does not have a high refractive index.
Therefore, in Patent Document 1, a polyester-based adhesive is proposed in place of the acrylic resin-based adhesive.

JP 2009-25575 A

  However, the technique disclosed in Patent Document 1 contains a polyester-based resin having a certain degree of high refractive index as the pressure-sensitive adhesive composition, but is further in terms of the diffusion efficiency of the light diffusion film and the light extraction efficiency. There is a demand for polyester resins having a high refractive index.

  Therefore, in the present invention, in order to obtain an adherend, particularly an adhesive sheet for an optical member, as well as a polyester-based pressure-sensitive adhesive having a high refractive index, in addition to being excellent in adhesive strength to an adherend, particularly a polycarbonate material. An object of the present invention is to provide a polyester pressure-sensitive adhesive composition.

  However, as a result of intensive studies in view of such circumstances, the inventor of the present invention has high adhesiveness and high adhesiveness that have been difficult to achieve in the past, in an adhesive composed of an adhesive composition containing a polyester resin. A polyester-based pressure-sensitive adhesive having a refractive index was found, and the present invention was completed.

That is, according to the present invention, in the polyester-based pressure-sensitive adhesive composed of the pressure-sensitive adhesive composition [I] containing the polyester-based resin (A), the following adhesive force (α) is 10 N / 25 mm or more and the refractive index is 1. The first gist is a polyester-based pressure-sensitive adhesive having a viscosity of 530 or more.
Adhesive strength (α): When a polyester-based adhesive is formed on a substrate to form an adhesive sheet, it is attached to an adherend of a polycarbonate plate and autoclaved at 50 ° C. and 0.5 MPa for 20 minutes, and then 24 hours. 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min with respect to the adherend later.

  Furthermore, this invention makes the 2nd summary the adhesive sheet for optical members which has an adhesive layer which consists of the said polyester-type adhesive.

  Moreover, this invention contains the polyester-type resin (A), a hydrolysis inhibitor (B), and a crosslinking agent (C), and the polyester-type resin (A) is a structural site derived from aliphatic polyvalent carboxylic acids. And a polyester-based pressure-sensitive adhesive composition containing a structural part derived from an aromatic polyhydric alcohol.

Further, the present invention provides a polyester-based pressure-sensitive adhesive comprising a pressure-sensitive adhesive composition containing a polyester-based resin (A) and an inorganic oxide (E), wherein the following adhesive force (β) is 5 N / 25 mm or more, and A polyester adhesive having a refractive index of 1.530 or more is a fourth gist.
Adhesive strength (β): Adhesion after a polyester adhesive is formed on a substrate to form an adhesive sheet, which is attached to an adherend of a glass plate and left at 23 ° C. and 50% RH for 30 minutes. 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min.

  In the present invention, when a polyester resin having a high glass transition temperature is applied to the pressure-sensitive adhesive, the rigid structure such as aromatics is eliminated as much as possible, the glass transition temperature is lowered by introducing an alkyl group-derived component, It is necessary to make it. Further, fine adjustment of the glass transition temperature is generally performed by adjusting an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid, and introduction of an aromatic diol should be avoided. On the other hand, in order to increase the refractive index, it is effective to introduce a structure having a high electron density, that is, an aromatic ring or the like, but as described above, introduction of an aromatic ring is not suitable for application to an adhesive. However, in the present invention, by selecting an acid component and an alcohol component that constitute a polyester-based resin, a high refractive index and an adhesive performance, both of which have been contradictory in the past, are achieved at the same time.

  The polyester-based pressure-sensitive adhesive of the present invention is excellent in adhesive force to an adherend, particularly a polycarbonate material, has a high refractive index, and is useful as a pressure-sensitive adhesive sheet for optical members.

Hereinafter, although it demonstrates in detail about the structure of this invention, these show an example of a desirable embodiment.
In the present invention, the term “carboxylic acids” includes carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters in addition to carboxylic acids.

The polyester-based pressure-sensitive adhesive of the present invention comprises a pressure-sensitive adhesive composition [I] containing a polyester-based resin (A), that is, the pressure-sensitive adhesive composition [I] is cured.
And as this polyester-type adhesive, the adhesive force ((alpha)) in the following measurement is 10 N / 25mm or more, and refractive index is 1.530 or more.
Adhesive strength (α): When a polyester-based adhesive is formed on a substrate to form an adhesive sheet, it is attached to an adherend of a polycarbonate plate and autoclaved at 50 ° C. and 0.5 MPa for 20 minutes, and then 24 hours. 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min with respect to the adherend later.

  Specifically, the measurement of the adhesive strength (α) can be performed as follows, for example.

  That is, the pressure-sensitive adhesive composition [I] was applied on a polyethylene terephthalate (PET) film having a thickness of 50 μm using an applicator and dried at 100 ° C. for 3 minutes to form a pressure-sensitive adhesive composition layer (thickness 25 μm). Then, the surface of the obtained pressure-sensitive adhesive composition layer is covered with a release-treated PET film (release film) and subjected to an aging treatment at 40 ° C. for 10 days to obtain a pressure-sensitive adhesive sheet with a release film. The release film is peeled off and attached to the polycarbonate plate adherence by two reciprocations with a 2 kg roller, followed by autoclaving at 50 ° C. and 0.5 MPa for 20 minutes, and after 24 hours, a peeling rate of 300 mm / By measuring 180 degree peel strength (N / 25 mm) in min, the adhesive strength (α) is determined.

  In the present invention, the adhesive strength (α) of the polyester-based pressure-sensitive adhesive is 10 N / 25 mm or more, preferably 15 N / 25 mm or more, and particularly preferably 20 N / 25 mm or more. When the adhesive force (α) is too small than the above range, the adhesion reliability is lowered due to poor adhesion. The upper limit of the adhesive strength (α) is usually 200 N / 25 mm, preferably 100 N / 25 mm, particularly preferably 80 N / 25 mm.

  In the present invention, the polyester adhesive has a refractive index of 1.530 or more, preferably 1.530 to 1.650, more preferably 1.540 to 1.640, and particularly preferably 1.550. ˜1.630, particularly preferably 1.560 to 1.620. If the refractive index is too smaller than the above range, the effects of the present invention are not exhibited, and there is a possibility that problems such as interfacial reflection occur and brightness decrease when laminated with an optical film. In addition, when too large, it will become higher than the refractive index of an optical film, and when it laminate | stacks with an optical film, there exists a tendency for interface reflection to occur and to produce malfunctions, such as a brightness | luminance falling.

  The refractive index in this invention is a refractive index with respect to D line | wire (589 nm) in 23 degreeC, and is measured using the Abbe refractometer DR-M4 by an Atago company.

In the polyester-based pressure-sensitive adhesive of the present invention, in order to satisfy the above-mentioned pressure-sensitive adhesive force and refractive index, it is preferable to form a pressure-sensitive adhesive using the pressure-sensitive adhesive composition [I] containing the polyester-based resin (A). The pressure-sensitive adhesive composition [I] preferably comprises the following polyester resin (A), hydrolysis inhibitor (B) and cross-linking agent (C) from the viewpoint of adhesive strength and durability. It is preferable to further contain a plasticizer (D) from the viewpoint of improving the initial adhesion, and it is preferable to further include an inorganic oxide (E) from the viewpoint of improving the refractive index.
Hereinafter, each component will be sequentially described.

<Polyester resin (A)>
The polyester resin (A) used in the present invention is obtained by copolymerizing a copolymer component containing polyvalent carboxylic acids (A1) and polyhydric alcohol (A2) as constituent raw materials. Especially, it is preferable from the point of the balance of adhesive force and refractive index that it contains the structural site | part derived from aliphatic polyhydric carboxylic acids and the structural site | part derived from aromatic polyhydric alcohol.

[Polyvalent carboxylic acids (A1)]
As polyvalent carboxylic acids (A1) used in the present invention, for example,
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 Diglycolic acid, or aliphatic dicarboxylic acids such as these carboxylic acids;
Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid, naphthalenedicarboxylic acid, or carboxylic acids thereof;
1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, adamantanedicarboxylic acid, or these carboxylic acids Alicyclic dicarboxylic acids such as acids;
And other divalent carboxylic acids.
These may be used alone or in combination of two or more.

  Among these, from the viewpoint of imparting tackiness, it is preferable to include aliphatic dicarboxylic acids, particularly preferably including aliphatic dicarboxylic acids having 4 to 12 carbon atoms, and more preferably including sebacic acids. .

  The content ratio of the aliphatic dicarboxylic acids is preferably 20 mol% or more, particularly preferably 50 to 95 mol%, more preferably 70 to 90 mol%, based on the whole polyvalent carboxylic acids (A1). It is. If the content is too low, the glass transition temperature tends to be high and sufficient adhesive strength tends not to be obtained.

  Moreover, aromatic dicarboxylic acids can also be included from the point which provides cohesive force among the above, for example, isophthalic acids are mentioned.

  The content ratio of the aromatic dicarboxylic acids is preferably 50 mol% or less, particularly preferably 5 to 40 mol%, more preferably 10 to 30 mol%, based on the whole polyvalent carboxylic acids (A1). It is. If the content is too high, the glass transition temperature tends to be high and sufficient adhesive performance tends not to be obtained.

  In the present invention, aromatic polycarboxylic acids and aliphatic dicarboxylic acids can be used in combination as polyvalent carboxylic acids (A1) from the viewpoint of the balance of adhesive properties, and the content ratio (molar ratio) is aromatic dicarboxylic acids. It is preferable that acids / aliphatic dicarboxylic acids = 0/100 to 90/10, particularly preferably aromatic dicarboxylic acids / aliphatic dicarboxylic acids = 1/99 to 49/51, more preferably aromatic dicarboxylic acids / fats. Group dicarboxylic acids = 10/90 to 30/70.

[Sulfonic acid group-containing dicarboxylic acids (A1-1)]
In the present invention, the sulfonate group-containing dicarboxylic acid (A1-1) is used as the polyvalent carboxylic acid (A1) from the viewpoint of improving the compatibility when an inorganic oxide (E) described later is added. preferable. Such a sulfonate group-containing dicarboxylic acid (A1-1) is not particularly limited as long as it is a monomer component having both a carboxyl group and a sulfonate group in the molecule. For example, sodium sulfonate or Phthalic acid, isophthalic acid, terephthalic acid and mono- or diesters thereof containing an alkali metal sulfonate such as potassium sulfonate are preferably used. These sulfonate group-containing dicarboxylic acids (A1-1) can be used alone or in combination of two or more.

  Specific examples of the sulfonate group-containing dicarboxylic acids (A1-1) include, for example, dimethyl sodium 4-sulfoisophthalate, sodium 5-sulfoisophthalate, dimethyl sodium 5-sulfoisophthalate, and dimethyl 4-sulfoisophthalate. Potassium, dimethylpotassium 5-sulfoisophthalate, sodium 2-sulfoterephthalate, potassium 2-sulfoterephthalate, dimethylsodium 2-sulfoterephthalate, dimethylpotassium 2-sulfoterephthalate, etc., sodium diethylene glycol sodium 2-sulfoterephthalate Etc. Among these, dimethyl sodium 5-sulfoisophthalate is preferably used.

  The proportion of the sulfonate group-containing dicarboxylic acid (A1-1) in the polyvalent carboxylic acid (A1) is 0.001 to 20 mol% with respect to the entire polyvalent carboxylic acid (A1). Is preferably 0.01 to 10 mol%, more preferably 0.03 to 5 mol%, and particularly preferably 0.05 to 2 mol%. If the amount of the sulfonate group-containing dicarboxylic acid (A1-1) is too small, compatibility with the inorganic oxide (E) tends to decrease when an inorganic oxide (E) described later is added, and the haze is large. Tends to be reduced (transparency is lowered), and if it is too much, durability tends to be lowered.

  For the purpose of increasing branch points in the polyester resin (A), trivalent or higher polyvalent carboxylic acids can also be used. Examples of such trivalent or higher carboxylic acids include trimellitic acid and pyromellitic acid. , Adamantanetricarboxylic acid, trimesic acid, or these carboxylic acids. Among them, it is preferable to use trimellitic acids from the viewpoint that gelation hardly occurs.

  The content ratio of the trivalent or higher polyvalent carboxylic acids is preferably 10 mol% or less, particularly preferably, based on the total of the polyvalent carboxylic acids (A1) in that the cohesive force of the pressure-sensitive adhesive can be increased. It is 0.1-5 mol%, and when there is too much this content, there exists a tendency for gelatinization to produce easily at the time of manufacture of a polyester-type resin (A).

[Polyhydric alcohol (A2)]
As the polyhydric alcohol (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, 1 , 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, tricyclodecane dimethanol, adamantanediol, 2,2,4,4-tetramethyl-1,3 -Alicyclic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, bisphenol S, bisphenol A, bisphenol fluorene, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5- Aromatic diols such as naphthalenediol and p-xylenediol;
And these ethylene oxide and propylene oxide adducts;
Aromatic diols such as dihydric alcohols such as

  Furthermore, in this invention, it is preferable to contain the fluorene type diol shown by following General formula (1) as aromatic diol.

In formula (1), R ₁ is an alkylene group having 1 to 5 carbon atoms, e.g., methylene, ethylene, propylene, butylene, and pentylene group. R ₂ , R ₃ , R ₄ and R ₅ are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group or an aralkyl group, which may be the same or different from each other.

Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a neopentyl group, and an isopentyl group.
Examples of the aryl group include aryl groups having 6 to 10 carbon atoms, such as a phenyl group, a tolyl group, and an o-xylyl group.
Examples of the aralkyl group include aralkyl groups having 7 to 20 carbon atoms, and examples thereof include a benzyl group and a phenethyl group.

In the fluorene-based diol represented by the general formula (1), R ₁ is preferably a methylene group or an ethylene group. R ₂ , R ₃ , R ₄ and R ₅ are preferably a hydrogen atom, a methyl group or an ethyl group, and a hydrogen atom is particularly preferred. And as this fluorene type compound, bisphenoxyethanol fluorene and bis (4- (2-hydroxyethoxy) phenyl) fluorene are preferably used from viewpoints of availability. One or two or more fluorene compounds can be used.
These dihydric alcohols may be used alone or in combination of two or more.

  In the present invention, among the polyhydric alcohols (A2), an aromatic diol is preferably included from the viewpoint that a high refractive index can be exhibited, and moreover, a plurality of aromatic rings are contained in one molecule. The fluorene-based diol is preferably included from the viewpoint of increasing the refractive index while maintaining adhesiveness.

  The content ratio of the aromatic diol in the polyhydric alcohol (A2) is preferably 10 to 100 mol%, particularly 15 to 80 mol%, more preferably 20 to 70 mol% with respect to the entire polyhydric alcohol (A2). %, In particular 25 to 60 mol%. When the content ratio is too low, it is difficult to obtain a sufficient refractive index, and when it is too high, the adhesive performance tends to be lowered.

  The content of the aromatic diol is preferably 10% by weight or more based on the whole polyester resin, more preferably 15 to 85% by weight, particularly 20 to 65% by weight, and particularly 25 to 60%. It is preferable that it is weight%. When the content ratio is too low, it is difficult to obtain a sufficient refractive index, and when it is too high, the adhesive performance tends to be lowered.

  Further, the content ratio of the fluorene-based diol is preferably 10 to 90 mol%, particularly 15 to 80 mol%, more preferably 20 to 70 mol%, especially with respect to the whole polyhydric alcohol (A2). Is preferably 25 to 60 mol%. When the content ratio is too low, it is difficult to obtain a sufficient refractive index, and when it is too high, the adhesive performance tends to be lowered.

  Further, the content ratio of the fluorene-based diol with respect to the whole aromatic diol is 50 mol% or more, particularly 60 mol% or more, more preferably 70 mol% or more, particularly 90 mol from the viewpoint of obtaining a sufficient refractive index. % Or more is preferable. Among them, it is particularly preferable that all are fluorene-based diols.

  Furthermore, in the present invention, among the above polyhydric alcohols (A2), it is preferable to include an aliphatic diol and an alicyclic diol from the viewpoint of excellent reactivity, and particularly preferably, the aliphatic diol includes, for example, ethylene. Glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and alicyclic Examples of the diol include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. It is particularly preferable to include an aliphatic diol from the viewpoint of balancing flexibility and exhibiting adhesive performance.

  The content of the aliphatic diol is preferably 1 to 90 mol%, particularly 10 to 85 mol%, more preferably 20 to 80 mol%, particularly 30 relative to the whole polyhydric alcohol (A2). It is preferable that it is -75 mol%. If the content is too low, the adhesive performance tends to decrease, and if it is too high, the refractive index tends to decrease.

  In addition, a trihydric or higher polyhydric alcohol can be used for the purpose of increasing branch points in the polyester resin (A). Examples of the trihydric or higher polyhydric alcohol include pentaerythritol, dipentaerythritol, and tripenta. Examples include erythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantanetriol and the like.

  The content ratio of the trihydric or higher polyhydric alcohol is preferably 10 mol% or less, particularly preferably 0.1 to 5 mol%, based on the whole polyhydric alcohol (A2). When there is too much this content rate, there exists a tendency for manufacture of a polyester-type resin (A) to become difficult.

  As a mixing ratio of the polyvalent carboxylic acid (A1) and the polyhydric alcohol (A2), the polyhydric alcohol (A2) is preferably 1 to 2.5 equivalents per equivalent of the polyvalent carboxylic acid (A1), Particularly preferred is 1.1 to 2.0 equivalents. If the content ratio of the polyhydric alcohol (A2) is too low, the acid value tends to be high and it becomes difficult to increase the molecular weight, and if it is too high, the yield tends to decrease.

  The polyester resin (A) used in the present invention is produced by arbitrarily selecting the polyvalent carboxylic acid (A1) and the polyhydric alcohol (A2) and subjecting them to a polycondensation reaction by a known method in the presence of a catalyst. Is done.

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

  In such esterification reaction, a catalyst is used. Specifically, for example, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, etc. Examples of the catalyst include catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Of these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the viewpoint of high catalytic activity and hue.

  The amount of the catalyst is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and still more preferably 20 to 3,000 ppm with respect to all copolymer components. If the blending amount is too small, the polymerization reaction tends not to proceed sufficiently, and if it is too large, there is no advantage such as shortening the reaction time and a side reaction tends to occur.

  About reaction temperature at the time of esterification reaction, 160-280 degreeC is preferable, Especially preferably, it is 180-250 degreeC, More preferably, it is 200-240 degreeC. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. The pressure during the reaction is usually under normal pressure.

After the esterification reaction is performed, a condensation reaction is performed.
As reaction conditions for the polycondensation reaction, a catalyst similar to that used in the above esterification reaction is further blended in the same amount, and the reaction temperature is preferably 220 to 280 ° C, particularly preferably 230 to 270 ° C. It is preferable that the system is gradually depressurized and finally reacted at 5 hPa or less.
If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur.

Thus, the polyester resin (A) used in the present invention is obtained.
The glass transition temperature of the polyester resin (A) is preferably 40 ° C. or less, particularly 30 ° C. or less, and more preferably 20 ° C. or less, from the viewpoint of the balance between the adhesive properties and the refractive index. When the glass transition temperature is too high, the flexibility is lost, the initial adhesiveness is lowered, and it becomes difficult to exert a sufficient adhesive force at a pressure of about finger pressure, so that the workability tends to be lowered. In addition, the minimum of glass transition temperature is -40 degreeC normally, Preferably it is -30 degreeC, More preferably, it is -20 degreeC.

Here, the glass transition temperature (Tg) of the polyester resin (A) 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 increase rate is 10 ° C / min.

  Moreover, the weight average molecular weight of the polyester resin (A) is preferably 8,000 to 200,000, particularly 10,000 to 180,000, more preferably 20,000 from the viewpoint of cohesive strength of the pressure-sensitive adhesive. It is preferable that it is 000-150,000. If the weight average molecular weight is too small, sufficient cohesive force cannot be obtained as a pressure-sensitive adhesive, and heat resistance and mechanical strength tend to decrease, and if it is too large, flexibility is lost and initial adhesiveness decreases, There is a tendency that it is difficult to exert a sufficient adhesive force at a pressure of about a finger pressure.

In addition, said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, a column: TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2) in a high performance liquid chromatography (the Tosoh company make, "HLC-8320GPC"). × 10 ⁶ , Theoretical plate number: 16,000 plate / line, Filler material: Styrene-divinylbenzene copolymer, Filler particle size: 4 μm) are used.

  The acid value of the polyester resin (A) is preferably 10 mgKOH / g or less, particularly 3 mgKOH / g or less, more preferably 1 mgKOH / g or less, and particularly preferably 0.5 mgKOH / g or less. If the acid value is too high, there is a concern that corrosion will occur when a layer of metal or the like comes on one side of the pressure-sensitive adhesive layer made of the present polyester-based pressure-sensitive adhesive. For example, when it becomes the structure used as a metal oxide thin film layer, corrosion occurs and there exists a tendency for the electroconductivity of a metal oxide film to fall.

  In addition, the acid value of the said polyester-type resin (A) is calculated | required by neutralization titration based on JISK0070.

  In the present invention, the refractive index of the polyester resin (A) alone is preferably 1.530 or more.

<Hydrolysis inhibitor (B)>
The polyester-based pressure-sensitive adhesive composition [I] in the present invention preferably contains a hydrolysis inhibitor (B) together with the polyester-based resin (A). This hydrolysis inhibitor (B) is contained in order to ensure long-term durability.

  The hydrolysis inhibitor (B) is not particularly limited, and a conventionally known one can be used. For example, the hydrolysis inhibitor (B) reacts with the carboxylic acid end group of the polyester resin (A) to bind. Examples thereof include compounds having a functional group such as a carbodiimide group, an epoxy group, and an oxazoline group. Among these, a carbodiimide group-containing compound is preferable in that it has a high effect of eliminating the catalytic activity of protons derived from carboxyl group end groups.

  As the carbodiimide group-containing compound, a known polycarbodiimide having one or more carbodiimide groups (—N═C═N—) in the molecule may be used, but the durability under higher temperature and higher humidity is improved. In terms of this point, a compound containing two or more carbodiimide groups in the molecule is preferable, particularly a compound containing three or more, more preferably five or more, and particularly preferably seven or more. In addition, when 30 or more are contained, the molecular structure becomes excessively large, which tends to be undesirable. It is also preferable to use a high molecular weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate 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 condensation reaction.

  Examples of the diisocyanate 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.

  Examples of commercially available carbodiimide group-containing compounds include Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd. Among them, Carbodilite (registered trademark) V-01, V-03, V-05, V -07 and V-09 are preferable in terms of excellent compatibility with organic solvents.

  As said epoxy compound, a glycidyl ester compound, a glycidyl ether compound, etc. are preferable, for example.

  Specific examples of the glycidyl ester compound include, for example, glycidyl benzoate, glycidyl t-Bu-benzoate, glycidyl p-toluate, glycidyl cyclohexane carboxylic acid, glycidyl pelargonate, glycyl stearate, lauric acid Glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester, Isophthalic acid diglycidyl ester, phthalic acid diglycidyl ester, naphthalenedicarboxylic acid diglycidyl Ester, methyl terephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, cyclohexanedicarboxylic acid diglycidyl ester, adipic acid diglycidyl ester, succinic acid diglycidyl ester, sebacic acid diglycidyl ester, dodecane Examples include diionic diglycidyl ester, octadecanedicarboxylic acid diglycidyl ester, trimellitic acid triglycidyl ester, and pyromellitic acid tetraglycidyl ester. These may be used alone or in combination of two or more.

  Specific examples of the glycidyl ether compound include, for example, phenylglycidyl ether, o-phenylglycidyl 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- [р- (β, γ-epoxypropoxy) phenyl] propane, 2,2-bis- (4-hydroxyphenyl) propane and 2,2-bis- (4-hydroxyphenyl) ) Bisglycidyl polyether obtained by the reaction of bisphenol such as methane and epichlorohydrin can be mentioned. It can be used in combination with the above.

  The oxazoline 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′-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'-ethylene Bis (2-oxazoline), 2,2′-tetramethylene bis (2-oxazoline), 2,2′-hexamethylene bis (2-oxazoline), 2,2′-octamethylene bis (2-oxazoline), 2 , 2′-Decamethylenebis (2-oxazoline), 2,2′-ethylenebis (4-methyl-2-oxazoline), 2,2′-tetramethylenebis (4,4-dimethyl-2-oxa Phosphorus), 2,2′-9,9′-diphenoxyethanebis (2-oxazoline), 2,2′-cyclohexylenebis (2-oxazoline), 2,2′-diphenylenebis (2-oxazoline) Among them, 2,2′-bis (2-oxazoline) is most preferable from the viewpoint of reactivity with polyester. These may be used alone or in combination of two or more.

  As these hydrolysis inhibitors (B), those having lower volatility are preferred, and therefore, those having a high number average molecular weight are preferably used, and usually 300 to 10,000, preferably 1,000 to 5,000. Use one.

  Among the hydrolysis inhibitors (B), it is preferable to use a carbodiimide group-containing compound. The carbodiimide equivalent in that case becomes like this. Preferably it is 50-10000, Especially it is preferable that it is 100-1000, Furthermore, it is 150-500. In addition, a carbodiimide equivalent shows the chemical formula amount per carbodiimide group.

  The content of the hydrolysis inhibitor (B) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight with respect to 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). If the content is too small, sufficient durability tends to be difficult to obtain.

The content of the hydrolysis inhibitor (B) is preferably optimized according to the acid value of the polyester resin (A), and the polyester system in the pressure-sensitive adhesive composition [I] The molar ratio ((b) / (a)) of the total amount (b) of the functional groups of the hydrolysis inhibitor (B) in the pressure-sensitive adhesive composition to the total acid value (a) of the resin (A) is: It is preferable that 0.5 ≦ (b) / (a), particularly preferably 1 ≦ (b) / (a) ≦ 1,000, and more preferably 1.5 ≦ (b) / (a) ≦ 100. It is.
When the content ratio of (b) with respect to (a) is too high, the compatibility with the polyester resin (A) tends to decrease, or the adhesive strength, cohesive strength, and durability performance tend to decrease. When the content ratio of b) is too low, the heat-and-moisture resistance tends to decrease.

<Crosslinking agent (C)>
The polyester-based pressure-sensitive adhesive composition [I] in the present invention contains the polyester-based resin (A) and preferably further contains a hydrolysis inhibitor (B), but is usually a crosslinking agent (C). The polyester resin (A) is cross-linked with the cross-linking agent (C) and becomes excellent in cohesive force, and the performance as a pressure-sensitive adhesive is improved by containing the cross-linking agent (C).

  Examples of the crosslinking agent (C) include compounds having a functional group that reacts with a hydroxyl group and / or a carboxyl group contained in the polyester resin (A), such as a polyisocyanate compound and a polyepoxy compound. Among these, it is particularly preferable to use a polyisocyanate compound from the viewpoint that both initial tackiness, mechanical strength, and heat resistance can be balanced.

  Examples of such polyisocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, 1 , 5-naphthalene diisocyanate, triphenylmethane triisocyanate, and the like, and adducts of the above polyisocyanates with polyol compounds such as trimethylolpropane, burettes of these polyisocyanate compounds, isocyanurates Body, etc. In addition, the said polyisocyanate type compound can also use what the isocyanate part was blocked with phenol, lactam, etc. These crosslinking agents (C) may be used individually by 1 type, and may be used in mixture of 2 or more types.

The content of the cross-linking agent (C) can be appropriately selected depending on the molecular weight of the polyester resin (A) and the purpose of use, but is usually 1 equivalent of the hydroxyl group and / or carboxyl group contained in the polyester resin (A). On the other hand, it is preferable that the reactive group contained in the crosslinking agent (C) contains the crosslinking agent (C) at a ratio of 0.2 to 10 equivalents, particularly preferably 0.5 to 5 equivalents, more preferably. Is 0.5 to 3 equivalents.
If the number of equivalents of reactive groups contained in the cross-linking agent (C) is too small, the cohesive force tends to decrease and sufficient heat resistance tends not to be obtained. It tends to be lowered, and sufficient adhesive force cannot be exhibited at a pressure of about the finger pressure.

In addition, when mix | blending a crosslinking agent (C), it is preferable to contain a catalyst simultaneously.
Examples of such catalysts include metal catalysts such as tin, lead, bismuth compounds, transition metal compounds such as iron, copper, titanium, zirconium, nickel, cobalt, and manganese, acetylacetonate complexes, and tertiary as nonmetal catalysts. An amine compound etc. are mentioned. From the viewpoint of catalytic activity, organotin, organotitanium, and organozirconium are preferred.

<Plasticizer (D)>
Thus, a pressure-sensitive adhesive composition [I] containing a polyester resin (A), preferably further containing a hydrolysis inhibitor (B) and a crosslinking agent (C) is obtained. In the present invention, a plasticizer ( D) is preferably contained. Such a plasticizer (D) is contained in order to ensure the adhesiveness even when the glass transition temperature of the resin is excessively increased in order to increase the refractive index.

  Examples of the plasticizer (D) include alkyl esters of aromatic polycarboxylic acids and alkyl esters of aliphatic polycarboxylic acids. Among them, an aromatic polyvalent carboxylic acid alkyl ester is preferable and a trivalent or higher valent aromatic polyvalent carboxylic acid alkyl ester is more preferable in that a plastic effect can be exhibited without a large decrease in refractive index.

  The content of the plasticizer (D) is preferably 2 to 30 parts by weight, particularly preferably 3 to 20 parts by weight, and more preferably 4 to 4 parts by weight with respect to 100 parts by weight of the polyester resin (A). 10 parts by weight. If the content is too large, the adhesive strength tends to decrease due to bleed-out of the plasticizer. If the content is too small, the adhesive strength tends to decrease due to a decrease in conformability.

<Inorganic oxide (E)>
In the present invention, it is preferable to further contain an inorganic oxide (E). Since the inorganic oxide (E) has a relatively high refractive index, it is contained for the purpose of increasing the refractive index of the pressure-sensitive adhesive layer. Is preferred. Furthermore, the adhesive force as a polyester-type adhesive can also be improved by mix | blending inorganic oxide (E).

That is, in the polyester-based pressure-sensitive adhesive composed of the pressure-sensitive adhesive composition containing the polyester-based resin (A) and the inorganic oxide (E), the following adhesive force (β) is 5 N / 25 mm or more and the refractive index is 1. A polyester-based pressure-sensitive adhesive having a viscosity of 530 or more can be obtained.
Adhesive strength (β): Adhesion after a polyester adhesive is formed on a substrate to form an adhesive sheet, which is attached to an adherend of a glass plate and left at 23 ° C. and 50% RH for 30 minutes. 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min.

  When the inorganic oxide (E) is contained, the refractive index can be further increased, and the refractive index is 1.530 or more, preferably 1.560 or more, more preferably 1 .600 or more, particularly preferably 1.620 or more. The upper limit is usually 1.700, preferably 1.680. More preferably, it is 1.660.

  Although there is no restriction | limiting in particular as an inorganic oxide (E), A metal oxide is preferable. Among them, a particle containing a metal oxide and an organic substance having a reactive functional group that modifies the surface thereof, more specifically, a reactive functional group that modifies the metal oxide particle and the surface of the particle. Coated particles (hereinafter also referred to as reactive modified metal oxide particles) containing an organic substance having a hydrogen atom are preferred. The reactive functional group may be in a state having an interaction such as a hydrogen bond with the metal oxide, or may be in a state capable of interacting with another substance without being in such a state. The inorganic oxide (E) is preferably inorganic oxide fine particles in a fine particle state, and examples of the inorganic oxide fine particles include fine particle powders, pastes, and sols. Is a sol.

As the metal oxide, a metal oxide generally used as a filler in a resin is preferably used. Examples of such a metal oxide include zirconium oxide (ZrO ₂ : zirconia) and titanium oxide (TiO ₂ : Titania), aluminum oxide (Al ₂ O ₃ : alumina), iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ), copper oxide (CuO), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ : yttria) , Niobium oxide (Nb ₂ O ₅ ), molybdenum oxide (MoO ₃ , MoO ₂ ), indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), tantalum oxide (Ta ₂ O ₅ , TaO ₂ ), tungsten oxide (WO _3, WO _2), lead oxide (PbO), bismuth oxide (Bi ₂ O _3), cerium oxide (CeO _2: ceria), antimony oxide _{(Sb 2 O 3, Sb 2} O ₅ ), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), phosphorus-doped tin oxide (PTO), zinc antimonate (AZO), indium-doped zinc oxide (IZO), aluminum Examples include doped zinc oxide and gallium-doped zinc oxide. Examples of the non-metal oxide include silicon oxide (SiO ₂ : silica) or boron oxide (B ₂ O ₃ ) that is generally used as a filler for resins. These metal oxides and nonmetal oxides may be used alone or in combination. Among these, zirconium oxide (ZrO ₂ : zirconia) and titanium oxide (TiO ₂ : titania) are preferable from the viewpoint of easily obtaining a high refractive index adhesive.

  Examples of reactive functional groups in organic substances having reactive functional groups include hydroxyl groups, phosphoric acid groups, carboxyl groups, amino groups, alkoxy groups, isocyanate groups, acid halides, acid anhydrides, glycidyl groups, chlorosilane groups, and alkoxy groups. A silane group is mentioned. As the organic substance having a reactive functional group, an organic substance having an isocyanate group is particularly preferable because the stability between the metal oxide and the surrounding substance can be improved. Examples of organic substances having an isocyanate group include acryloxymethyl isocyanate, methacryloxymethyl isocyanate, acryloxyethyl isocyanate, methacryloxyethyl isocyanate, acryloxypropyl isocyanate, methacryloxypropyl isocyanate, 1,1-bis (acryloxymethyl) Ethyl isocyanate is mentioned.

  In the reactive modified metal oxide particles, the content of the organic substance having a reactive functional group is preferably 1 to 40 parts by weight with respect to 100 parts by weight of the metal oxide.

  Reactive modified metal oxide particles are mixed with metal oxide particles, organic substances having a reactive functional group, an organic solvent, and optional additives that can be added as necessary. Accordingly, by performing treatment such as ultrasonic treatment, a suspension in which particles are dispersed in an organic solvent can be obtained.

  Examples of the organic solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, methanol, ethanol, isopropyl alcohol, n-butanol, iso-butanol and the like Alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and other ethers, ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether Esters such as acetate and propylene glycol monoethyl ether acetate, dimethylforma De, N, N- dimethyl acetoacetamide, amides such as N- methylpyrrolidone. As the organic solvent, one of these may be used alone, or two or more of them may be mixed and used. Examples of optional additives that can be added to the mixture include metal chelating agents.

  When the reactive modified metal oxide particles are obtained as a suspension in which the particles are dispersed in an organic solvent, conditions such as the amount of the solvent are adjusted, and the reactive modified metal oxide particles are 1 in the suspension. It is preferable from the viewpoint of the ease of production and the like that the content is adjusted so as to be contained by ˜50% by weight and used as it is for the production of the pressure-sensitive adhesive composition.

  In preparing the mixture, each component is preferably mixed by a bead mill or the like. By such mixing, secondary particles or higher-order particles can be pulverized to the primary particle level, and the surface can be treated in the form of primary particles. As a result, uniform surface treatment can be performed.

  The mixture can be further sonicated as needed. The ultrasonic treatment can be performed using an apparatus such as an ultrasonic cleaning machine, an ultrasonic homogenizer, or an ultrasonic dispersing machine. By such treatment, a good suspension can be obtained.

Commercially available particles may be used as they are as the reactive modified metal oxide particles. Although the said commercially available particle | grain may be provided as a slurry containing components, such as a solvent and an additive, it can be used as a material of the adhesive composition of this invention in the state of the slurry containing this component as it is. As an example of a slurry of reactive modified metal oxide particles containing ZrO ₂ as a metal oxide, a trade name “NANON5 ZR-010” (manufactured by Solar Co., Ltd., solvent: methyl ethyl ketone, particle content 30%, surface modified An organic substance having a reactive functional group: an isocyanate having a polymerizable functional group, and a volume average particle diameter of 15 nm). As an example of a slurry of reactive modified metal oxide particles containing TiO ₂ as a metal oxide, a trade name “NOD-742GTF” (manufactured by Nagase ChemteX Corporation, solvent: polyethylene glycol monomethyl ether, particle content 30%, Volume average particle diameter of 48 nm).

  The volume average particle diameter of the inorganic oxide (E) is preferably 5 nm or more, more preferably 10 nm or more, particularly preferably 20 nm or more, on the other hand, preferably 50 nm or less, more preferably 40 nm or less. And particularly preferably 30 nm or less. By setting the particle diameter within the above numerical range, an adhesive layer with little coloration and high light transmittance can be obtained, and the dispersion of particles becomes easy. When the reactive modified metal oxide aggregates to form secondary particles or higher order particles, the particle size range may be the primary particle size range. The particle diameter can be measured by using a dynamic light scattering particle size distribution analyzer (Nanotrac Wave-EX150, manufactured by Nikkiso Co., Ltd.) and using the volume as a particle diameter standard.

  The lower limit of the content ratio of the inorganic oxide (E) in the pressure-sensitive adhesive composition is preferably 10 parts by weight or more, particularly preferably 40 parts by weight or more with respect to 100 parts by weight of the polyester resin (A). More preferably, it is 90 parts by weight or more. On the other hand, the upper limit of the content of the inorganic oxide (B) is 500 parts by weight or less, preferably 400 parts by weight or less, more preferably 300 parts by weight with respect to 100 parts by weight of the polyester resin (A). It is as follows. When there is too little content of an inorganic oxide (B), there exists a tendency for a desired refractive index not to be obtained, and when there is too much, there exists a tendency for adhesive force to fall.

In the present invention, in addition to the polyester resin (A), hydrolysis inhibitor (B), cross-linking agent (C), plasticizer (D), and inorganic oxide (E), the effects of the present invention are achieved. As long as they are not damaged, additives such as conventionally known antioxidants, softeners, ultraviolet absorbers, stabilizers, antistatic agents, tackifiers, etc., and other inorganic or organic fillers, metal powders, pigments, etc. Additives such as powder and particles can be blended.
In addition, about the said tackifier, it is preferable not to contain substantially from the point of durability and transparency.

The polyester-based pressure-sensitive adhesive of the present invention is composed of the pressure-sensitive adhesive composition [I], that is, the pressure-sensitive adhesive composition [I] is cured.
In the polyester-based pressure-sensitive adhesive of the present invention, when the adhesive force (α) is adjusted to 10 N / 25 mm or more and the refractive index is adjusted to 1.530 or more, for example, (1) a raw material for the polyester-based resin (A) In the composition, among polyvalent carboxylic acids and / or polyhydric alcohols, a method of blending a large amount of raw materials having an aromatic ring, (2) In the raw material composition of the polyester-based resin (A), polyvalent carboxylic acids and / or many Among polyhydric alcohols, a method of adding many raw materials having an aromatic ring and adding a plasticizer to the polyester resin (A) having a glass transition temperature of −20 ° C. to 40 ° C., (3) polyester resin ( A) includes a method of adding an inorganic oxide (E) having a high refractive index, (4) a combination of (1) to (3), and the balun of cost, refractive index and adhesive performance. A preferable process at the point where the easy to take (1) or (2), particularly preferably the method of (2).
Further, as a method for further increasing the refractive index, a method combining (2) and (3) is preferable.

Such a polyester-based pressure-sensitive adhesive preferably does not substantially contain an acidic group. Specifically, the acid value is preferably 10 mgKOH / g or less, particularly preferably 5 mgKOH / g or less, more preferably 1 mgKOH / g or less, particularly preferably 0.5 mgKOH / g or less.
In addition, the acid value of the said polyester-type adhesive can be calculated | required by the method similar to the acid value of the said polyester-type resin (A).

  The polyester-based pressure-sensitive adhesive composition [I] of the present invention can be used for bonding various members. Among them, the polyester-based pressure-sensitive adhesive composition [I] is preferably used as a pressure-sensitive adhesive for optical members used for bonding optical members. The optical member with the pressure-sensitive adhesive layer can be obtained by laminating and forming the pressure-sensitive adhesive layer of the polyester-based pressure-sensitive adhesive composed of the pressure-sensitive adhesive composition [I] on the optical member.

  Such optical members include ITO electrode films and transparent electrode films such as inorganic and organic conductive films such as polythiophene, polarizing plates, retardation plates, elliptical polarizing plates, optical compensation films, brightness enhancement films, electromagnetic wave shielding films, An infrared absorption film, AR (anti-reflection) film, etc. are mentioned. Among these, it is effective when the optical member is a transparent electrode film, and is preferable in that high adhesive force is obtained, and an ITO electrode film is particularly preferable. The ITO electrode film is often formed as a thin film on a substrate such as glass or PET, but in the present invention, a film in which the ITO electrode film is formed as a thin film on a PET substrate may be used. Particularly preferred. Moreover, it is suitable also for the light extraction film provided in the light emission surface of the surface light-emitting body of an organic EL element, or the light-diffusion sheet | seat of a liquid crystal display.

  In the optical member with the pressure-sensitive adhesive layer, it is preferable to further provide a release sheet on the surface opposite to the optical member surface of the pressure-sensitive adhesive layer, and when put into practical use, the release sheet is peeled off, Adhesive layer and adherend are bonded together. As such a release sheet, a silicon-based release sheet is preferably used.

  Further, the polyester-based pressure-sensitive adhesive of the present invention can be used as a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive of the present invention on one side or both sides of a support substrate, and in particular, an optical material used for bonding optical members. It is suitable as an adhesive sheet for members. Moreover, it is also preferable to set it as the base material-less double-sided adhesive sheet which does not have a support base material at the point which is excellent in transparency and the adhesive force with respect to the thickness to comprise is high. In the present invention, “sheet” is described as meaning including “film” and “tape”.

<Adhesive sheet>
An adhesive sheet can be produced as follows, for example.
Such a pressure-sensitive adhesive sheet can be produced according to a known general pressure-sensitive adhesive sheet production method. For example, the pressure-sensitive adhesive composition [I] is coated on a substrate sheet and dried, and the opposite side is produced. A pressure-sensitive adhesive sheet of the present invention having a pressure-sensitive adhesive layer made of the polyester-based pressure-sensitive adhesive of the present invention on a substrate is obtained by pasting a release sheet on the surface of the pressure-sensitive adhesive layer and curing as necessary.

  Alternatively, the pressure-sensitive adhesive sheet of the present invention can also be obtained by coating and drying the pressure-sensitive adhesive composition [I] on the release sheet, pasting a base sheet on the opposite pressure-sensitive adhesive layer surface, and curing as necessary. Is obtained.

Moreover, a base material-less double-sided pressure-sensitive adhesive sheet can be produced by forming a pressure-sensitive adhesive layer on the release sheet and bonding the release sheet to the opposite pressure-sensitive adhesive layer surface.
At the time of use, the obtained pressure-sensitive adhesive sheet or substrate-less double-sided pressure-sensitive adhesive sheet peels the release sheet from the pressure-sensitive adhesive layer and bonds the pressure-sensitive adhesive layer and the adherend.

  Examples of the substrate include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, boribylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride, Polyfluorinated ethylene resins such as polyvinylidene fluoride and polyfluorinated ethylene; polyamides such as nylon 6 and nylon 6,6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl Alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate Acrylic resin such as polybutyl acrylate; polystyrene; polycarbonate; polyarylate; polyimide; synthetic resin sheet such as cycloolefin polymer, aluminum, copper, iron metal foil, fine paper, glassine paper, glass fiber, natural Examples thereof include woven fabrics and nonwoven fabrics made of fibers, synthetic fibers, and the like. These base material sheets can be used as a single layer body or a multilayer body in which two or more kinds are laminated.

  Among these, a base sheet made of polyethylene terephthalate and polyimide is particularly preferable, polyethylene terephthalate is particularly preferable in terms of excellent adhesion to the pressure-sensitive adhesive, and further, polyethylene terephthalate having a metal thin film layer is preferable. It is preferable in that the adhesive strength between the material and the pressure-sensitive adhesive is excellent, the base material can be stably maintained without corroding the metal thin film layer, and the effect of the polyester pressure-sensitive adhesive of the present invention can be exhibited remarkably.

In the present invention, the ITO electrode film has a pressure-sensitive adhesive layer on the PET side of the film formed as a thin film on the PET base material, and the PET base material and the polycarbonate film are laminated via the pressure-sensitive adhesive layer, Furthermore, it is also preferable to set it as the optical laminated body by which an acrylic film is laminated | stacked (layer structure: ITO electrode film / PET base material / adhesive layer / PC system film / acrylic film).
Moreover, it is preferable that the refractive index of the base film adjacent to the pressure-sensitive adhesive layer is 1.52 to 1.63 when the light-extractability is good when bonded to the pressure-sensitive adhesive of the present invention.

  As the release sheet, for example, various synthetic resin sheets exemplified in the base material, paper, cloth, non-woven fabric and the like can be used. As the release sheet, it is preferable to use a silicon-based release sheet.

  As thickness of the said base material, it is preferable that it is 1-1000 micrometers, for example, Especially preferably, it is 2-500 micrometers, More preferably, it is 3-300 micrometers.

  As a coating method of the pressure-sensitive adhesive composition [I], for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater or the like may be used.

  As conditions for the curing treatment, the temperature is usually room temperature to 70 ° C., the time is usually 1 day to 30 days, and specifically, for example, 23 ° C. for 1 day to 20 days, preferably 23 ° C. for 3 days. What is necessary is just to carry out on conditions, such as 14 days and 40 degreeC for 1 day-10 days.

  As drying conditions, the drying temperature is preferably 60 to 140 ° C, particularly preferably 80 to 120 ° C, and the drying time is preferably 0.5 to 30 minutes, particularly preferably 2 to 5 minutes.

  The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the substrate-less double-sided pressure-sensitive adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 200 μm, and more preferably 10 to 100 μm. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease. If the thickness is too thick, it is difficult to apply uniformly, and problems such as bubbles entering the coating film tend to occur. is there. In consideration of impact absorption, the thickness is preferably 50 μm or more.

  In addition, the thickness of the said adhesive layer is a value calculated | required by deducting the measured value of the thickness of structural members other than an adhesive layer from the measured value of the thickness of the whole adhesive sheet using Mitutoyo "ID-C112B". It is.

  About the gel fraction of the adhesive layer of the said adhesive sheet, it is preferable that it is 20% or more from the point of durable performance and adhesive force, Especially preferably, it is 30 to 90%, More preferably, it is 40 to 70%. If the gel fraction is too low, durability tends to decrease due to a decrease in cohesion. If the gel fraction is too high, there is a concern that the adhesive force is reduced due to the increase in cohesive force.

The gel fraction is a measure of the degree of crosslinking, and is calculated, for example, by the following method.
That is, a pressure-sensitive adhesive sheet (not provided with a separator) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, polyethylene terephthalate film or the like) as a base material is wrapped with a 200-mesh SUS wire mesh, and 23 in toluene. The weight percentage of the insoluble pressure-sensitive adhesive component immersed in the wire mesh at 24 ° C. for 24 hours is defined as the gel fraction. However, the weight of the substrate is subtracted.

  Further, the pressure-sensitive adhesive sheet may be protected by providing a release sheet outside the pressure-sensitive adhesive layer as necessary. Further, in the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on one side of the base material, the pressure-sensitive adhesive layer is applied to the surface of the base material opposite to the pressure-sensitive adhesive layer by using a release treatment surface. It is also possible to protect.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded. In the examples, “parts” and “%” mean weight basis.
Moreover, regarding the measurement of the weight average molecular weight of a polyester-type resin in the following Example and a glass transition temperature, it measured according to the above-mentioned method. The acid value of the polyester resin was measured by neutralization titration based on JIS K0070 after dissolving 1 g of the polyester resin in 30 g of a mixed solvent of 7/3 (weight ratio) (toluene / methanol).

<Production of polyester resin (A)>
The mol described in the following production examples indicates a molar ratio when the total amount of the polyvalent carboxylic acid components is 1.0 mol.

[Production Example 1: Production of polyester resin (A-1)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 42.9 parts (1.0 mol) of sebacic acid as a polyvalent carboxylic acid component (A1), a polyol component (A2) As neopentyl glycol 15.5 parts (0.7 mol), 1,4-butanediol 13.4 parts (0.7 mol), and trimethylolpropane 0.4 parts (0.013 mol), bisphenoxyethanol 27.9 parts (0.3 mol) of fluorene and 0.01 part of tetrabutyl titanate as a catalyst were charged, the temperature was gradually raised to an internal temperature of 250 ° C., and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 parts of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was performed over 3 hours to produce a polyester resin (A-1).
The obtained polyester resin (A-1) had a weight average molecular weight of 65,000, a glass transition temperature of −18 ° C., an acid value of 0.7 mgKOH / g, and a refractive index of 1.537.
The ratio of the finished components is as follows: sebacic acid = 100 mol% as the polyvalent carboxylic acid component, and neopentyl glycol / 1.4-butanediol / trimethylolpropane / bisphenoxyethanol fluorene = 33. They were 4 mol% / 36.5 mol% / 0.8 mol% / 29.3 mol%.

[Production Example 2: Production of polyester resin (A-2)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 40.1 parts (1.0 mol) of sebacic acid as a polyvalent carboxylic acid component (A1), polyol component (A2) As neopentyl glycol 12.4 parts (0.6 mol), 1,4-butanediol 12.4 parts (0.7 mol), trimethylolpropane 0.3 parts (0.013 mol), bisphenoxyethanol 34.7 parts (0.4 mol) of fluorene and 0.01 part of tetrabutyl titanate as a catalyst were charged, the temperature was gradually raised to an internal temperature of 250 ° C., and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 parts of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was performed for 3 hours to produce a polyester resin (A-2).
The obtained polyester resin (A-2) had a weight average molecular weight of 36,000, a glass transition temperature of −4 ° C., an acid value of 1.0 mgKOH / g, and a refractive index of 1.553.
The ratio of the finished components is as follows: sebacic acid = 100 mol% as the polyvalent carboxylic acid component, and neopentyl glycol / 1.4-butanediol / trimethylolpropane / bisphenoxyethanol fluorene = 26. They were 3 mol% / 33.9 mol% / 0.8 mol% / 39.0 mol%.
Met.

[Production Example 3: Production of polyester resin (A-3)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 37.6 parts (1.0 mol) of sebacic acid as a polyvalent carboxylic acid component (A1), polyol component (A2) As neopentyl glycol 9.7 parts (0.5 mol), 1,4-butanediol 11.7 parts (0.7 mol), and trimethylolpropane 0.3 parts (0.013 mol), bisphenoxyethanol 40.7 parts (0.5 mol) of fluorene and 0.01 part of tetrabutyl titanate as a catalyst were charged, the temperature was gradually raised to an internal temperature of 250 ° C., and an esterification reaction was performed over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 parts of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was performed for 3 hours to produce a polyester resin (A-3).
The obtained polyester resin (A-3) had a weight average molecular weight of 41,000, a glass transition temperature of 14 ° C., an acid value of 1.2 mgKOH / g, and a refractive index of 1.566.
The ratio of the finished components is as follows: sebacic acid = 100 mol% as the polyvalent carboxylic acid component, and neopentyl glycol / 1.4-butanediol / trimethylolpropane / bisphenoxyethanol fluorene = 19. They were 6 mol% / 31.0 mol% / 0.7 mol% / 48.7 mol%.
Met.

[Production Example 4: Production of polyester resin (A-4)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 40.3 parts (0.95 mol) of sebacic acid and dimethyl sodium sulfonylisophthalate as the polyvalent carboxylic acid component (A1) 3.1 parts (0.05 mol), as the polyol component (A2), 15.3 parts (0.7 mol) neopentyl glycol, 13.2 parts (0.7 mol) 1,4-butanediol and tri 0.4 parts (0.013 mol) of methylolpropane, 27.6 parts (0.3 mol) of bisphenoxyethanol fluorene and 0.01 part of tetrabutyl titanate as a catalyst were added, and the temperature was gradually raised to an internal temperature of 250 ° C. The esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 parts of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was performed for 3 hours to produce a polyester resin (A-4).
The obtained polyester resin (A-4) had a weight average molecular weight of 46,000, a glass transition temperature of −27 ° C., an acid value of 1.0 mgKOH / g, and a refractive index of 1.537.
The ratio of the finished components was as follows: sebacic acid / sodium sulfonylisophthalate = 95 mol% / 5 mol% as the polyvalent carboxylic acid component, and neopentyl glycol / 1.4-butanediol / trimethyl as the polyhydric alcohol component. Methylolpropane / bisphenoxyethanol fluorene = 33.4 mol% / 36.5 mol% / 0.8 mol% / 29.3 mol%.

[Production Example 5: Production of polyester resin (A-5)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 45.9 parts (0.8 mol) of sebacic acid, 7.1 of isophthalic acid as a polyvalent carboxylic acid component (A1) Parts (0.15 mol), 4.2 parts (0.05 mol) of dimethyl sodium sulfonylisophthalate, 26.6 parts (0.9 mol) of neopentyl glycol as polyol component (A2), 1,4-butane Diol 12.8 parts (0.5 mol), 1.6-hexanediol 2.9 parts (0.087 mol) and trimethylolpropane 0.5 parts (0.013 mol), tetrabutyl titanate 0 as catalyst .01 part was charged, the temperature was gradually raised to an internal temperature of 250 ° C., and the esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 parts of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was performed for 3 hours to produce a polyester resin (A-5).
The obtained polyester resin (A-5) had a weight average molecular weight of 51,000, a glass transition temperature of −49 ° C., an acid value of 0.8 mgKOH / g, and a refractive index of 1.490.
The ratio of the finished components is as follows: sebacic acid / isophthalic acid / sodium sulfonylisophthalate = 80 mol% / 15 mol% / 5 mol% as the polyvalent carboxylic acid component, and neopentyl glycol / 1 as the polyhydric alcohol component. 4-butanediol / 1.6-hexanediol / trimethylolpropane = 58.7 mol% / 34.1 mol% / 6.2 mol% / 1.0 mol%.

[Production Example 6: Production of polyester resin (A′-1)]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 9.6 parts (0.2 mol) of isophthalic acid and 46.8 sebacic acid were added as the polyvalent carboxylic acid component (A1). Parts (0.8 mol), as the polyol component (A2), 27.1 parts (0.9 mol) of neopentyl glycol, 13.0 parts (0.5 mol) of 1,4-butanediol, 1,6- Hexanediol 3.0 parts (0.09 mol), trimethylolpropane 0.5 parts (0.013 mol), and tetrabutyl titanate 0.01 parts as a catalyst were charged, and the temperature was gradually raised to an internal temperature of 250 ° C. The esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.01 parts of tetrabutyl titanate was added as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was performed over 3 hours to produce a polyester resin (A′-1). .
The obtained polyester-based resin (A′-1) had a weight average molecular weight of 70,000, a glass transition temperature of −50 ° C., an acid value of 0.4 mgKOH / g, and a refractive index of 1.486.
The finished composition is sebacic acid / isophthalic acid = 80 mol% / 20 mol% as the polyvalent carboxylic acid component, and neopentyl glycol / 1.4-butanediol / 1.6-hexane as the polyhydric alcohol component. Diol / trimethylolpropane = 54.8 mol% / 38.4 mol% / 0.9 mol% / 5.9 mol%.
Met.

[Production Example 7: Production of polyester resin (A′-2)]
As a polyvalent carboxylic acid component (A1), 22.9 parts (0.64 mol) of naphthalenedicarboxylic acid dimethyl ester (NDCM) was added to a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus. , 65.8 parts (1.0 mol) of bisphenoxyethanol fluorene (BPEF) as a polyol component (A2) and 0.01 part of tetrabutyl titanate as a catalyst were gradually raised to an internal temperature of 250 ° C. The esterification reaction was performed over time. Subsequently, after cooling to 200 ° C., as a carboxylic acid anhydride, 11.3 parts (0.36 mol) of pyromellitic anhydride (PMAn) was charged and reacted at 170 ° C. for 2 hours while dissolving, A polyester resin (A′-2) was produced.
The obtained polyester-based resin (A′-2) had a weight average molecular weight of 2000, a glass transition temperature of 173 ° C., an acid value of 32 mgKOH / g, and a refractive index of 1.652.

<Hydrolysis inhibitor (B)>
The following were prepared as the hydrolysis inhibitor (B).
(B-1) Carbodiimide group-containing hydrolysis inhibitor (Nisshinbo Chemical Co., Ltd .; trade name “Carbodilite V-07”)

<Crosslinking agent (C)>
The following were prepared as a crosslinking agent (C).
(C-1) Trimethylolpropane / tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd .; product name “Coronate L55E”)

<Plasticizer (D)>
The following were prepared as the plasticizer (D).
(D-1) Trioctyl trimellitic acid (TOTM)
(D-2) Dioctyl phthalate (DOP)

<Inorganic oxide (E)>
The following were prepared as the inorganic oxide (E).
(E-1) AX-ZP-158-A (Nippon Shokubai Co., Ltd. zirconium oxide dispersion)
(E-2) NANON5 ZR-010 (Solar Corporation Zirconium Oxide Dispersion)
(E-3) ZIRCOSTAR ZP-153 (zirconium oxide dispersion manufactured by Nippon Shokubai Co., Ltd.)

<Catalyst>
The following were prepared as catalysts.
・ Dibutyltin dilaurate (DBTL)

<Antioxidant>
The following were prepared as antioxidants.
・ Hindered phenol antioxidant / Irganox 1010 (BASF)

(Examples 1-14, Comparative Examples 1-3)
The polyester resin obtained above is diluted with ethyl acetate to a solid content concentration of 50%, and each component is blended as shown in Table 1 with respect to 200 parts of the polyester resin solution (solid content of 100 parts) and stirred. By mixing, a polyester pressure-sensitive adhesive composition was obtained.
Evaluation was performed as follows using the obtained polyester-based pressure-sensitive adhesive composition.

<Manufacture of pressure-sensitive adhesive sheet with release film>
Each of the polyester-based pressure-sensitive adhesive compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 3 was applied onto a polyethylene terephthalate (PET) film having a thickness of 50 μm using an applicator and dried at 100 ° C. for 3 minutes. Then, the pressure-sensitive adhesive composition layer (thickness 25 μm) is formed, and then the surface of the obtained pressure-sensitive adhesive composition layer is covered with a release-treated PET film (release film) and subjected to aging treatment at 40 ° C. for 10 days. And a pressure-sensitive adhesive sheet with a release film was obtained.

  Using this pressure-sensitive adhesive sheet with a release film, the gel fraction, adhesive strength, and optical performance (refractive index, transparency) were evaluated as follows. The results are summarized in Table 1.

[Gel fraction (%)]
The release film of the pressure-sensitive adhesive sheet with the release film obtained above is peeled off, wrapped in a 200-mesh SUS wire mesh, immersed in toluene at 23 ° C. for 24 hours, and the insoluble pressure-sensitive adhesive component remaining in the wire mesh The weight percentage was determined as the gel fraction. However, the weight of the substrate was subtracted.

[Adhesive strength (N / 25mm)]
After peeling off the release film of the pressure-sensitive adhesive sheet with the release film obtained above and pasting it to the adherend of the polycarbonate plate with a 2 kg roller, and after autoclaving at 50 ° C. and 0.5 MPa for 20 minutes After 24 hours, the adhesive strength was determined by measuring 180 degree peel strength (N / 25 mm) at a peel rate of 300 mm / min. For the measurement of adhesive strength, an autograph (“Autograph AGS-H 500N” manufactured by Shimadzu Corporation) was used. The evaluation criteria for adhesive strength are as follows.
(Evaluation criteria)
○: 20 N / 25 mm or more ×: Less than 20 N / 25 mm

[Refractive index]
The pressure-sensitive adhesive sheet with a release film obtained above is allowed to stand at 23 ° C. for 3 hours, the release film is peeled off, and the pressure-sensitive adhesive layer side is subjected to D line (589 nm) using an Abbe refractive system DR-M4 manufactured by Atago Co., Ltd. ) Was measured.

[transparency]
The transparency of the pressure-sensitive adhesive sheet with a release film obtained above was visually observed.
○ ・ ・ ・ Transparent △ ・ ・ ・ Slightly turbid ×× Muddy

  From the above results, in Examples 1 to 14, an adhesive having excellent adhesive strength and a very high refractive index was obtained, whereas Comparative Examples 1 and 2 had a low refractive index. In Comparative Example 3, since the glass transition point was too high, the refractive index was high, but the adhesive properties were not obtained, and both the refractive index and the adhesive strength were not satisfied.

  In the said Examples 10-14, initial stage adhesive force was also evaluated as follows. The results are shown in Table 2.

[Initial adhesive strength (N / 25mm)]
The release film of the pressure-sensitive adhesive sheet with a release film obtained above was peeled off, and the adherend of the glass plate was subjected to 23 ° C. and 50% R.D. H. The adhesive strength was determined by measuring the 180 degree peel strength (N / 25 mm) at a peel rate of 300 mm / min after 30 minutes of pasting by reciprocating with a 2 kg roller. For the measurement of adhesive strength, an autograph (“Autograph AGS-H 500N” manufactured by Shimadzu Corporation) was used. The evaluation criteria for adhesive strength are as follows.
(Evaluation criteria)
○: 5N / 25mm or more △: 0.5N / 25mm or more, less than 5N / 25mm ×: Less than 0.1N / 25mm

  From the above results, in Examples 10 to 14, the addition of the inorganic oxide resulted in good results for the initial adhesive strength in addition to the improvement of the refractive index.

(Reference Examples 1-6)
The polyester resin obtained above is diluted with ethyl acetate to a solid content concentration of 50%, and 200 parts of this polyester resin solution (solid content of 100 parts) is blended with an inorganic oxide as shown in Table 3, A polyester resin composition was obtained by stirring and mixing.
Using the obtained polyester resin composition, the refractive index and the transparency were evaluated as follows. The results are shown in Table 3.

[Refractive index]
The refractive index of D line (589 nm) was measured for the polyester-based resin composition obtained above using an Abbe refractive system DR-M4 manufactured by Atago Co., Ltd.

[transparency]
The transparency of the polyester resin composition obtained above was visually observed.
○ ・ ・ ・ Transparent △ ・ ・ ・ Slightly turbid ×× Muddy

  From the above results, in Reference Examples 1 to 5, when an inorganic oxide is blended, a sulfonate group-containing dicarboxylic acid is contained as a copolymer component of the polyester resin, so that the compatibility is good in addition to the refractive index. It was excellent in transparency. Reference Example 6 had a good refractive index due to the blending of the inorganic oxide, but was slightly inferior in transparency because it did not contain sulfonate group-containing dicarboxylic acids as a copolymerization component.

  The polyester-based pressure-sensitive adhesive of the present invention can be used as a pressure-sensitive adhesive for electronic parts, a pressure-sensitive adhesive for bonding optical members, a pressure-sensitive adhesive for soft vinyl chloride, and the like. In particular, the polyester-based pressure-sensitive adhesive of the present invention is excellent in adhesion to an adherend, particularly a polycarbonate material, and has a high refractive index, and therefore can be suitably used for bonding optical members.

Claims (15)

In the polyester-based pressure-sensitive adhesive composed of the pressure-sensitive adhesive composition [I] containing the polyester-based resin (A), the following adhesive force (α) is 10 N / 25 mm or more and the refractive index is 1.530 or more. A polyester-based pressure sensitive adhesive.
Adhesive strength (α): When a polyester-based adhesive is formed on a substrate to form an adhesive sheet, it is attached to an adherend of a polycarbonate plate and autoclaved at 50 ° C. and 0.5 MPa for 20 minutes, and then 24 hours. 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min with respect to the adherend later.   The pressure-sensitive adhesive composition [I] contains a polyester resin (A), a hydrolysis inhibitor (B), and a crosslinking agent (C), and the polyester resin (A) is derived from aliphatic polycarboxylic acids. The polyester-based pressure-sensitive adhesive according to claim 1, wherein the polyester-based pressure-sensitive adhesive comprises a structural part derived from the above and a structural part derived from aromatic polyhydric alcohol.   3. The polyester-based pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive composition [I] further contains a plasticizer (D).   The polyester-based pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the polyvalent carboxylic acid (A1) which is a constituent material of the polyester-based resin (A) contains an aliphatic polyvalent carboxylic acid.   The polyester-based pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the polyhydric alcohol (A2) which is a constituent material of the polyester-based resin (A) contains an aromatic polyhydric alcohol.   The polyester-based pressure-sensitive adhesive according to claim 1, wherein the polyester-based resin (A) has a glass transition temperature of 40 ° C. or lower.   The polyester-based pressure-sensitive adhesive according to any one of claims 1 to 6, wherein the polyester-based resin (A) has a weight average molecular weight of 8,000 to 200,000.   Content of a hydrolysis inhibitor (B) is 0.01-10 weight part with respect to 100 weight part of polyester-type resin (A), The polyester-type adhesion | attachment in any one of Claims 2-7 characterized by the above-mentioned. Agent.   The polyester pressure-sensitive adhesive according to any one of claims 3 to 8, wherein the content of the plasticizer (D) is 2 to 30 parts by weight with respect to 100 parts by weight of the polyester resin (A).   The polyester-based pressure-sensitive adhesive according to any one of claims 1 to 9, further comprising an inorganic oxide (E).   A pressure-sensitive adhesive sheet for optical members, wherein the polyester-based pressure-sensitive adhesive according to claim 1 is formed on a substrate.   A polyester-based resin (A), a hydrolysis inhibitor (B), and a cross-linking agent (C) are included. A polyester-based pressure-sensitive adhesive composition comprising a derived structural part.   The polyester pressure-sensitive adhesive composition according to claim 12, further comprising a plasticizer (D).   The polyester-based pressure-sensitive adhesive composition according to claim 12 or 13, further comprising an inorganic oxide (E). In the polyester pressure-sensitive adhesive comprising the pressure-sensitive adhesive composition containing the polyester resin (A) and the inorganic oxide (E), the following adhesive force (β) is 5 N / 25 mm or more and the refractive index is 1.530. A polyester-based pressure-sensitive adhesive characterized by the above.
Adhesive strength (β): Adhesion after a polyester adhesive is formed on a substrate to form an adhesive sheet, which is attached to an adherend of a glass plate and left at 23 ° C. and 50% RH for 30 minutes. 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min.