JP7003538B2 - Adhesive layer, adhesive sheet and resin composition - Google Patents

Description

The present invention relates to an adhesive layer and an adhesive sheet made of a polyester resin. More specifically, the present invention has low adhesive strength at room temperature, can be temporarily fixed to the extent that it can be reattached, and becomes strongly adhesive when heated. It relates to an adhesive layer and an adhesive sheet capable of firmly adhering to an adherend or adhering adherends to each other.

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

Further, in recent years, display devices such as liquid crystal displays (LCD: Liquid Crystal Display) and input devices used in combination with the above display devices such as touch panels have become widely used, and in the manufacture of these, optics have become widely used. A transparent adhesive sheet is used for bonding optical members such as films and base materials.

As such a pressure-sensitive adhesive sheet, for example, an acrylic pressure-sensitive adhesive whose molecular weight is lowered with a solvent-based thick coating pressure-sensitive adhesive and whose solid content is increased is used, and a pressure-sensitive adhesive sheet that can absorb impact and can be firmly attached (for example, Patent Document). 1) and a pressure-sensitive adhesive sheet (see, for example, Patent Document 2) that increases the adhesive strength by irradiating the adherend with an active energy ray after bonding have been proposed.

Japanese Unexamined Patent Publication No. 2012-21142 Japanese Unexamined Patent Publication No. 2013-234322

However, although the adhesive sheet of Patent Document 1 has sufficient adhesive strength when the optical members are bonded, the adhesive strength is strong for temporary fixing and re-bonding when the optical members are bonded. Further improvement in terms of sex is desired.
Further, the adhesive sheet of Patent Document 2 may have a low initial adhesive strength, but in order to increase the adhesive strength, it is necessary to irradiate with active energy rays, and a base material or an adherend that is weak against active energy rays is used. If there was, it was difficult to use. In addition, when ultraviolet rays, which are often used as active energy rays, are used, they may not be used on a base material or an adherend that does not transmit ultraviolet rays. If a thermal polymerization initiator is used, it can be used even with heat, but its storage stability is not sufficient.
As described above, in the bonding of optical members, an adhesive sheet having a low initial adhesive force so that temporary fixing and reattachment can be easily performed, and a viscous adhesive sheet capable of firmly adhering the members to each other after that is desired. ing.

Therefore, in the present invention, under such a background, the adhesive strength is low at room temperature (for example, 23 ° C.), the adhesive can be temporarily fixed to the extent that it can be reattached, and the adhesive becomes strong by heating and firmly adheres to the adherend. It is an object of the present invention to provide an adhesive layer and an adhesive sheet capable of firmly adhering adherends to each other.

However, as a result of diligent research in view of such circumstances, the present inventor has made an adhesive layer composed of an adhesive composition [I] containing a polyester resin (A) and a hydrolysis inhibitor (B) . When the adhesive layer is formed on the substrate and the adhesive sheet is formed together with the substrate, the adhesive strength at the initial stage of bonding is low, and the adhesive strength is initially adhered by heating. We have found an adhesive layer that is much larger than the force and completed the present invention.

That is, the gist of the present invention is a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition [I] containing a polyester-based resin (A) and a hydrolysis inhibitor (B) , and the above-mentioned pressure-sensitive adhesive. When the layer is formed on the base material to form an adhesive sheet together with the base material, the following initial adhesive force (α) is less than 1N / 25 mm, and the following time-dependent adhesive force (β) is initial. It relates to an adhesive layer having an adhesive strength (α) of 10 times or more.
Initial adhesive strength (α): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate under a 23 ° C. and 50% RH environment by reciprocating a 2 kg roller, and then pressed and attached under a 23 ° C. and 50% RH environment. Adhesive strength measured at 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min using an autograph after being left for 30 minutes.
Adhesive strength over time (β): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate at 23 ° C in a 50% RH environment by reciprocating a 2 kg roller, and heated in a 50 ° C environment for 5 days. Then, after returning to the environment of 23 ° C. and 50% RH and leaving for 30 minutes, the adhesive strength measured by 180 degree peeling strength (N / 25 mm) at a peeling speed of 300 mm / min using an autograph.

The second gist of the present invention is that the following adhesive force over time (γ) is 1 N / 25 mm or less, and the adhesive force over time (β) is 5 times or more the adhesive force over time (γ). It is about the agent layer.
Adhesive strength over time (γ): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate under a 23 ° C, 50% RH environment by reciprocating a 2 kg roller, and under a 23 ° C, 50% RH environment. Adhesive strength measured at 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min using an autograph after being left in the water for 2 days.

The adhesive layer of the present invention has low adhesive strength at room temperature and can be temporarily fixed to the extent that it can be reattached. It is a pressure-sensitive adhesive layer that can be bonded, and is useful for a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, and particularly useful for a pressure-sensitive adhesive sheet for bonding optical members.

Hereinafter, the configuration of the present invention will be described in detail, but these are examples of desirable embodiments.
In the present invention, "adhesive adhesion" refers to a state in which the adhesive is slightly adhesive to the extent that it can be reattached at the initial stage, and later becomes strongly adhesive due to heating or the like.
Further, the term "carboxylic acid" includes, in addition to carboxylic acid, a carboxylic acid derivative such as a carboxylic acid salt, a carboxylic acid anhydride, a carboxylic acid halide, and a carboxylic acid ester.

The adhesive layer of the present invention is an adhesive layer made of an adhesive composition [I] containing a polyester resin (A) and a hydrolysis inhibitor (B) , and is an adhesive layer. When the adhesive layer is formed on the base material and forms an adhesive sheet together with the base material, the following initial adhesive force (α) is less than 1N / 25 mm, and the following time-dependent adhesive force (β). Is more than 10 times the initial adhesive strength (α).
Initial adhesive strength (α): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate under a 23 ° C. and 50% RH environment by reciprocating a 2 kg roller, and then pressed and attached under a 23 ° C. and 50% RH environment. Adhesive strength measured at 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min using an autograph after being left for 30 minutes.
Adhesive strength over time (β): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate at 23 ° C in a 50% RH environment by reciprocating a 2 kg roller, and heated in a 50 ° C environment for 5 days. Then, after returning to the environment of 23 ° C. and 50% RH and leaving for 30 minutes, the adhesive strength measured by 180 degree peeling strength (N / 25 mm) at a peeling speed of 300 mm / min using an autograph.

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

First, the adhesive composition is applied onto a 100 μm thick polyethylene terephthalate (PET) film using an applicator, dried at 100 ° C. for 3 minutes, and the adhesive composition layer (25 μm thick) is applied. ) Is formed, and then the surface of the obtained adhesive composition layer is covered with a release-treated PET film (release film), aged at 40 ° C. for 4 days, and adhered with a release film. Make a release sheet.
The prepared adhesive sheet with a release film is cut into a size of 25 mm × 150 mm as a measurement sample, the release film is peeled off, and the adhesive layer side of the release film is placed at 23 ° C. and 50% RH environment. Underneath, a 2 kg roller is reciprocated on a glass plate to apply pressure, and after leaving it for 30 minutes in a 23 ° C, 50% RH environment, an autograph (manufactured by Shimadzu Corporation, "Autograph AGS-H 500N") is used. Therefore, the initial adhesive force (α) can be obtained by measuring the 180-degree peel strength (N / 25 mm) at a peeling speed of 300 mm / min.

Further, in the above-mentioned measurement of the adhesive force with time (β), specifically, for example, it can be performed as follows.

The release film of the adhesive sheet with a release film, which is a sample for measurement prepared in the above initial adhesive force (α), is peeled off, and the adhesive layer side of the adhesive sheet is heated at 23 ° C. and 50% RH. A 2 kg roller is reciprocated on a glass plate under the environment to apply pressure, heat it in a 50 ° C environment (especially in a state where humidity is not controlled) for 5 days, then return it to a 23 ° C, 50% RH environment and leave it for 30 minutes. After that, the adhesive strength over time (N / 25 mm) was measured by measuring the 180 degree peeling strength (N / 25 mm) at a peeling speed of 300 mm / min using an autograph (manufactured by Shimadzu Corporation, "Autograph AGS-H 500N"). β) is required.

In the present invention, the initial adhesive force (α) is less than 1N / 25mm, preferably 0.5N / 25mm or less, and particularly preferably 0.3N / 25mm or less. If the adhesive force (α) is too large, the adhesive force becomes too strong and cannot be used for temporary fixing to the extent that it can be reattached. The lower limit of the initial adhesive force (α) is usually 0.0001N / 25mm, but 0.02N / 25mm or more is preferable, and 0.05N / 25mm or more, because problems are less likely to occur during temporary fixing. Is preferable, and 0.08 N / 25 mm or more is particularly preferable.

Further, in the present invention, the adhesive force over time (β) is 10 times or more, preferably 15 to 1000 times, more preferably 20 to 100 times, the initial adhesive force (α). If the adhesive force over time is too smaller than the above-mentioned magnification, the adhesive sheet can be reattached at the initial stage, and the desired adhesive sheet, which becomes strongly adhesive over time, cannot be obtained.

Further, in the adhesive layer of the present invention, the following adhesive force over time (γ) is 1 N / 25 mm or less, and the adhesive force over time (β) is 5 times or more the adhesive force over time (γ). preferable.
Adhesive strength over time (γ): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate under a 23 ° C, 50% RH environment by reciprocating a 2 kg roller, and under a 23 ° C, 50% RH environment. Adhesive strength measured at 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min using an autograph after being left in the water for 2 days.

Specifically, the measurement of the adhesive force over time (γ) can be performed as follows.

The release film of the adhesive sheet with a release film, which is a sample for measurement prepared in the above initial adhesive force (α), is peeled off, and the adhesive layer side of the adhesive sheet is heated at 23 ° C. and 50% RH. A 2 kg roller is reciprocated on a glass plate in an environment to apply pressure, and after leaving it in a 23 ° C, 50% RH environment for 2 days, an autograph (manufactured by Shimadzu Corporation, "Autograph AGS-H 500N") is used. By measuring the 180-degree peeling strength (N / 25 mm) at a peeling speed of 300 mm / min, the adhesive force over time (γ) can be obtained.

In the present invention, the adhesive force over time (γ) is preferably 1 N / 25 mm or less, more preferably 0.8 N / 25 mm or less, and particularly preferably 0.6 N / 25 mm or less. If the adhesive force (γ) over time is too large, the adhesive becomes too strong, and it tends to be difficult to use it for temporary fixing to the extent that it can be reattached even when it is not heated. The lower limit of the adhesive force over time (γ) is usually 0.0001N / 25 mm, but 0.02 or more is preferable, and 0.05 or more is particularly preferable, because problems are less likely to occur during temporary fixing. Is preferably 0.1 or more.

Further, the adhesive force with time (β) is preferably 5 times or more, more preferably 8 to 1000 times, particularly preferably 10 to 100 times, the adhesive force with time (γ). If the adhesive force (β) over time is too smaller than the above-mentioned magnification, it tends to be possible to reattach at room temperature, and it tends to be difficult to obtain the desired adhesive sheet, which becomes strongly adhesive after heating.

The adhesive layer of the present invention is a layer obtained by curing the adhesive composition [I] containing the polyester resin (A) and the hydrolysis inhibitor (B) , and is usually such an adhesive layer. The coating layer is used as an adhesive sheet formed on the substrate.
It can also be used as a base material-less double-sided adhesive sheet without a base material. The base material-less double-sided adhesive sheet is an adhesive sheet having a structure in which release films are provided on both sides of the adhesive layer, and one of the release films is peeled off and bonded to the substrate. , Can be used as an adhesive sheet.

In the present invention, the adhesive composition [I] contains the following polyester resin (A) as an essential component and a hydrolysis inhibitor (B ) from the viewpoint of adhesive strength, and further. It is preferable to contain both the components (B) and (C).
Hereinafter, each component constituting the adhesive adhesive composition [I] will be sequentially described.

<Polyester resin (A)>
The polyester resin (A) used in the present invention is obtained by copolymerizing a copolymerization component containing a polyvalent carboxylic acid (A1) and a polyhydric alcohol (A2) as a constituent raw material. Among them, the polyhydric alcohol (A2) is at least the polyether glycol (A2-1) and the alkylene glycol (A2-2) in order to satisfy the values of the initial adhesive force (α) and the aging adhesive force (β). It is preferable to contain one of them from the viewpoint of the balance between the initial adhesive force and the adhesive force over time.

[Multivalent carboxylic acids (A1)]
The polyvalent carboxylic acid (A1) used in the present invention includes a divalent carboxylic acid and a trivalent or higher polyvalent carboxylic acid, and the divalent carboxylic acid is preferably used from the viewpoint of stably obtaining a polyester resin. ..

Examples of the divalent carboxylic acids include malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladiponic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebasic acids, fumaric acids, and the like. Aliphatic dicarboxylic acids such as maleic acids, itaconic acids, thiodipropionic acids, diglycolic acids, etc.;
Aromatic dicarboxylic acids such as terephthalic acids, isophthalic acids, benzylmaronic acids, diphenic acids, 4,4'-oxydibenzoic acids, naphthalene dicarboxylic acids, etc.;
Oil rings of 1,3-cyclopentane dicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,3-cyclopentane dicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5-norbornandicarboxylic acids, adamantandicarboxylic acids, etc. Group dicarboxylic acids; etc.
Examples of the trivalent or higher carboxylic acids include trimesic acids, pyromellitic acids, adamantane tricarboxylic acids, trimesic acids and the like.
These polyvalent carboxylic acids (A1) can be used alone or in combination of two or more.

Further, among the above polyvalent carboxylic acids (A1), it is preferable to include aromatic polyvalent carboxylic acids (A1-1) from the viewpoint of imparting cohesive force, and isophthalic acids are particularly preferably used.

The content ratio of the aromatic polyvalent carboxylic acid (A1-1) is preferably 30 mol% or more, particularly preferably 50 to 90 mol%, and further preferably 50 to 90 mol% with respect to the total polyvalent carboxylic acid (A1). It is preferably 60 to 80 mol%. If the content ratio is too low, the adhesive strength with time does not increase, and there is a tendency that sufficient adhesive performance cannot be obtained.

Further, among these, aliphatic polyvalent carboxylic acids can be contained from the viewpoint of imparting a tack feeling, and examples thereof include sebacic acids.

The content ratio of the aliphatic polyvalent carboxylic acid is preferably 50 mol% or less, particularly preferably 40 mol% or less, still more preferably 30 mol% or less, based on the total polyvalent carboxylic acid (A1). Is. If the content ratio is too high, the improvement of the adhesive strength with time tends to be insufficient.

In the present invention, aromatic polyvalent carboxylic acids (A1-1) and aliphatic polyvalent carboxylic acids can be used in combination as the polyvalent carboxylic acids (A1) from the viewpoint of sticky physical properties. The content ratio (molar ratio) of the aromatic polyvalent carboxylic acids (A1-1) and the aliphatic polyvalent carboxylic acids is as follows: aromatic polyvalent carboxylic acids (A1-1) / aliphatic polyvalent carboxylic acids = 30/70. It is preferably to 100/0, particularly preferably 50/50 to 100/0, and even more preferably 80/20 to 100/0.

It is preferable to use trivalent or higher-valent polyvalent carboxylic acids for the purpose of increasing the number of branch points in the polyester resin (A), and among them, trimellitic acids are used because gelation is relatively unlikely to occur. Is even more preferable.

The content ratio of the trivalent or higher polyvalent carboxylic acids is preferably 10 mol% or less, particularly preferably 10 mol% or less, based on the total polyvalent carboxylic acids (A1) in that the cohesive force of the pressure-sensitive adhesive can be enhanced. The content is 0.1 to 5 mol%, and if the content is too large, gelation tends to occur easily during the production of the polyester resin (A).

The content ratio of the polyvalent carboxylic acid (A1) is preferably 5% by weight or more, more preferably 8 to 50% by weight, particularly 10 to 30% by weight, based on the whole polyester resin (A). Is preferable. If the content ratio is too low, it tends to be difficult to obtain substrate adhesion, and if it is too high, the initial adhesive strength tends to increase.

[Multivalent alcohol (A2)]
Examples of the polyhydric alcohol (A2) used in the present invention include dihydric alcohols and trihydric or higher polyhydric alcohols.

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, and 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-hexanediol and other aliphatic diols;
1,2-Cyclohexanedimethanol, 1,3-Cyclohexanedimethanol, 1,4-Cyclohexanedimethanol, Spiroglycol, Tricyclodecanedimethanol, Adamantanediol, 2,2,4,4-Tetramethyl-1,3 -Alicyclic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol and theirs. Aromatic diols such as ethylene oxide and propylene oxide adducts;
And so on.
Examples of the trihydric or higher polyhydric alcohol include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol. Will be.
Further, polyether glycol (A2-1) such as polytetramethylene ether glycol, polyethylene glycol and polypropylene glycol can be mentioned.
The above-mentioned polyhydric alcohols (A2) can be used alone or in combination of two or more.

In the present invention, among the polyhydric alcohols (A2), it is preferable to contain polyether glycol (A2-1) because the initial adhesive strength can be lowered, and polytetramethylene ether glycol is particularly preferable. Used.

The content ratio of the polyether glycol (A2-1) in the polyhydric alcohol (A2) is preferably 10 to 99 mol% with respect to the total polyhydric alcohol (A2), particularly 30 to 98 mol%, and further. Is preferably 51 to 97 mol%. If the content ratio is too low, it tends to be difficult to obtain a sufficiently low initial adhesive strength, and if it is too high, it tends to be difficult to obtain a polyester resin.

Further, in the present invention, among the polyhydric alcohols (A2), it is preferable to contain alkylene glycol (A2-2) from the viewpoint of ease of polymerization, and the alkylene glycol (A2-2) is, for example, for example. Examples thereof include aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol (neopentyl glycol), and ethylene glycol is preferably used. Be done.

The content ratio of the alkylene glycol (A2-2) is preferably 1 to 90 mol%, particularly 2 to 70 mol%, and further 3 to 49 mol% with respect to the total polyhydric alcohol (A2). In particular, it is preferably 3.5 to 20 mol%. If the content ratio is too low, it tends to be difficult to obtain stable resin formation, and if it is too high, the adhesive strength with time at room temperature (23 ° C.) tends to increase.

Further, it is preferable to use a trihydric or higher polyhydric alcohol in the polyester resin (A) for the purpose of increasing branching points, and examples of such trihydric or higher polyhydric alcohols include pentaerythritol and dipentaerythritol. , Tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantantriol and the like.

The content ratio of the trivalent or higher polyhydric alcohol is preferably 20 mol% or less, more preferably 0.1 to 10 mol%, based on the total polyhydric alcohol (A2). In particular, 0.5 to 5.0 mol% is preferable, and if the content ratio is too large, the production of the polyester resin (A) tends to be difficult.

The content ratio of the polyhydric alcohol (A2) is preferably 15% by weight or more, more preferably 40 to 95% by weight, and particularly 70 to 90% by weight, based on the total polyester resin (A). Is preferable. If the content ratio is too low, the initial adhesive strength tends not to be sufficiently lowered, and if it is too high, the adhesive performance tends to be lowered.

The mixing ratio of the polyvalent carboxylic acid (A1) and the polyhydric alcohol (A2) is preferably 1 to 3.0 equivalent per 1 equivalent of the polyvalent carboxylic acid (A1). Particularly preferably, it is 1.1 to 2.0 equivalents. If the blending ratio of the polyhydric alcohol (A2) is too low, the acid value tends to be high and it tends to be difficult to increase the molecular weight, and if it is too high, the yield tends to decrease.

For the polyester resin (A) used in the present invention, the polyvalent carboxylic acids (A1) and the polyhydric alcohol (A2) are arbitrarily selected, and these are polycondensed by a known method in the presence of a catalyst. Manufactured.

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

In such an esterification reaction, a catalyst is used, and specifically, for example, a titanium-based catalyst such as tetraisopropyl titanate or tetrabutyl titanate, an antimony-based catalyst such as antimony trioxide, a germanium-based catalyst such as germanium dioxide, or the like. Examples thereof include catalysts and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these can be used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferable from the viewpoint of high catalytic activity and balance of hue.

The blending amount of the catalyst is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, still more preferably 20 to 3,000 ppm with respect to the total copolymerization component. If the blending amount is too small, the polymerization reaction tends to be difficult to proceed sufficiently, and if it 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 even more preferably 220 to 250 ° C. If the reaction temperature is too low, the reaction tends to be difficult to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. Further, the pressure at the time of reaction is usually under normal pressure.

After the above esterification reaction is carried out, a polycondensation reaction is carried out.
As the reaction conditions of the polycondensation reaction, the same catalyst as 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 to gradually reduce the pressure of the reaction system and finally react at 5 hPa or less. If the reaction temperature is too low, the reaction tends to be difficult 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 can be obtained.

The resin composition ratio (structural unit ratio derived from each component) of the polyester resin (A) can be obtained by, for example, NMR.

The glass transition temperature of the polyester resin (A) is preferably −100 to 40 ° C., particularly −80 to 0 ° C. or lower, and further −70 to −10 ° C. or lower from the viewpoint of adhesive properties. Is preferable. If the glass transition temperature is too high, the flexibility will be lost, the initial adhesiveness will decrease, the adhesive force will be difficult to exert at a pressure of about finger pressure, and the workability will tend to decrease, and if it is too low, the cohesive force will decrease. However, the adhesive sheet is easily deformed and tends to spoil the appearance.

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 −90 ° C. to 100 ° C., and the temperature rise rate is 10 ° C./min.

The weight average molecular weight of the polyester resin (A) is preferably 8,000 to 200,000 from the viewpoint of the cohesive force of the adhesive, particularly 10,000 to 180,000, and further. It is preferably 20,000 to 150,000. If the weight average molecular weight is too small, sufficient cohesive force cannot be obtained as a viscous adhesive, and the heat resistance and mechanical strength tend to decrease. If the weight average molecular weight is too large, gelation occurs during the production of the polyester resin (A). It tends to be easy and it is difficult to obtain resin.

The above weight average molecular weight is a weight average molecular weight converted to standard polystyrene molecular weight, and is shown on a high-speed liquid chromatograph (manufactured by Tosoh Corporation, “HLC-8320GPC”) as a column: TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2). It is measured by using two series of × ¹⁰⁶ , theoretical number of stages: 16,000 stages / piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm).

The acid value of the policetel-based resin (A) 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, there is a concern that it will corrode when a layer such as metal is laminated on one surface of the adhesive layer. For example, when the metal oxide thin film layer is formed, corrosion tends to occur and the conductivity of the metal oxide thin film tends to decrease.

The acid value of the polyester resin (A) is determined by neutralization titration based on JIS K 0070.

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

As the hydrolysis inhibitor (B), conventionally known ones can be used, and examples thereof include compounds that react with and bind to the carboxylic acid terminal group of the polyester resin (A), and specific examples thereof include the compound. Examples thereof include compounds having a functional group such as a carbodiimide group, an epoxy group, and an oxazoline group. Among these, the carbodiimide group-containing compound is preferable because it has a high effect of eliminating the catalytic activity of the proton derived from the carboxyl group terminal group.

As the carbodiimide group-containing compound, a known polycarbodiimide having at least one carbodiimide group (-N = C = N-) in the molecule may be usually used, but the durability at higher temperature and higher humidity is improved. In terms of points, a compound containing two or more carbodiimide groups in the molecule, that is, a polyvalent carbodiimide-based compound is preferable, and in particular, a compound containing three or more, further five or more, and particularly seven or more. Is preferable. If 30 or more are contained, the molecular structure becomes too large, which tends to be unfavorable. It is also preferable to use a high molecular weight polycarbodiimide produced by decarboxylating and condensing diisocyanate in the presence of a carbodiimidization catalyst.

Examples of such high molecular weight polycarbodiimides include those obtained by decarboxylating and condensing the following diisocyanates.

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

Examples of commercially available carbodiimide group-containing compounds include the carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd., among which carbodilite (registered trademark) V-01, V-03, V-05, and V- 07 and V-09 are preferable because they have excellent compatibility with organic solvents.

As the epoxy group-containing compound, for example, a glycidyl ester compound, a glycidyl ether compound, or the like is preferable.

Specific examples of the glycidyl ester compound include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, and 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, naphthalenedicarboxylic acid diglycidyl ester, methylterephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, cyclohexanedicarboxylic acid diglycidyl ester, adipic acid Examples thereof include diglycidyl ester, succinic acid diglycidyl ester, sebacic acid diglycidyl ester, dodecandionic acid diglycidyl ester, octadecane dicarboxylic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, and the like. It can be used alone or in combination of two or more.

Specific examples of the glycidyl ether compound include phenylglycidyl ether, o-phenyl glycidyl ether, 1,4-bis (β, γ-epoxypropoxy) butane, and 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, and 2,2-bis- (4-hydroxyphenyl) propane and 2,2-bis- (4-hydroxy) Examples thereof include bisglycidyl polyether obtained by the reaction of bisphenol such as phenyl) methane with epichlorohydrin, and these can be used alone or in combination of two or more.

As the oxazoline group-containing compound, a bisoxazoline compound or the like is preferable. 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-cyclohexazoline), 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'-diphenoxyetambis (2-oxazoline), 2,2'-cyclohexylenebis (2-oxazoline), 2 , 2'-Diphenylene bis (2-oxazoline) and the like can be exemplified, and among these, 2,2'-bis (2-oxazoline) is most preferable from the viewpoint of reactivity with polyester. In addition, these can be used alone or in combination of two or more.

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

Among the hydrolysis inhibitors (B), it is preferable to use a carbodiimide group-containing compound. At that time, the carbodiimide equivalent is preferably 50 to 10,000, particularly preferably 100 to 1,000, and more preferably 150 to 500. The carbodiimide equivalent indicates 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, based on 100 parts by weight of the polyester resin (A). , More preferably 0.2 to 3 parts by weight. If the content is too large, turbidity tends to occur due to poor compatibility with the polyester resin (A), and if it is too small, sufficient durability tends to be difficult to obtain.

Further, the content of the hydrolysis inhibitor (B) is preferably optimized according to the acid value of the polyester resin (A), and is contained in the adhesive composition [I]. The molar ratio of the total number of moles of the functional group (b) of the hydrolysis inhibitor (B) in the adhesive composition to the total number of moles (a) of the acidic functional groups of the polyester resin (A) (((). b) / (a)) is preferably 0.5 ≦ (b) / (a), particularly preferably 1 ≦ (b) / (a) ≦ 1,000, and even more preferably 1.5 ≦. (B) / (a) ≦ 100.
If the content ratio of (b) to (a) is too high, the compatibility with the polyester resin (A) tends to decrease, and the adhesive strength, cohesive force, and durability performance tend to decrease. If the content of b) is too low, the moisture resistance and heat resistance performance tends to deteriorate.

<Crosslinking agent (C)>
The adhesive composition [I] used in the present invention contains the polyester resin (A) and further contains a hydrolysis inhibitor (B), but is usually a cross-linking agent ( It is preferable to contain C), and by containing the cross-linking agent (C), the polyester resin (A) is cross-linked with the cross-linking agent (C) to have excellent cohesive power, and the performance as a pressure-sensitive adhesive. To improve.

Examples of the cross-linking agent (C) include compounds having a functional group that reacts with at least one of a hydroxyl group and a carboxyl group contained in the polyester-based resin (A), such as a polyisocyanate-based compound and a polyepoxy-based compound. Among these, it is particularly preferable to use a polyisocyanate compound from the viewpoint of achieving both initial adhesiveness, mechanical strength, and heat resistance in a well-balanced manner.

Examples of such polyisocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydride diphenylmethane diisocyanate, xylylene diisocyanate, hydride xylylene diisocyanate, tetramethylxylylene diisocyanate, 1. , 5-Naphthalenediocyanate, triphenylmethane triisocyanate, etc., and examples thereof include an adduct of the above polyisocyanate and a polyol compound such as trimethylolpropane, and a buretto body of these polyisocyanate compounds, isocyanate. Nurate body, etc. may be mentioned. The polyisocyanate compound may be used even if the isocyanate portion is blocked with phenol, lactam or the like. These cross-linking agents (C) may be used alone or in combination of two or more.

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 usually, at least one equivalent of the hydroxyl group and the carboxyl group contained in the polyester resin (A). On the other hand, it is preferable that the reactive group contained in the cross-linking agent (C) contains the cross-linking agent (C) in a proportion of 0.2 to 10 equivalents, particularly preferably 0.5 to 5 equivalents, and further. It is preferably 0.5 to 3 equivalents.
If the equivalent number of the reactive groups contained in the cross-linking agent (C) is too small, the cohesive force tends to decrease and the initial adhesive force tends to increase, and if it is too large, the flexibility decreases and the thermal adhesive force increases. It tends to be difficult.

When the cross-linking agent (C) is blended, it is preferable that the catalyst (D) is contained at the same time.
Examples of the catalyst (D) include metal catalysts such as tin-based, lead, and bismuth compounds, transition metal compounds such as iron, copper, titanium, zirconium, nickel, cobalt, and manganese, acetylacetonate complexes, and non-metal catalysts. Examples thereof include tertiary amine compounds. From the viewpoint of catalytic activity, organotin-based, organic titanium, and organic zirconium are preferable.

Further, in the reaction between the polyester resin (A) and the cross-linking agent (C), an organic solvent having no functional group that reacts with these components (A) and (C), for example, esters such as ethyl acetate and butyl acetate. , Ketones such as methyl ethyl ketone and methyl isobutyl ketone, and organic solvents such as aromatics such as toluene and xylene can be used. These can be used alone or in combination of two or more.

In the adhesive composition [I] used in the present invention, in addition to the above-mentioned polyester resin (A), hydrolysis inhibitor (B), cross-linking agent (C), and catalyst (D), the present invention Additives such as antioxidants (E) such as hindered phenols, softeners, ultraviolet absorbers, stabilizers, antistatic agents, tackifiers, etc., and other inorganic or organic substances, as long as the effects of the invention are not impaired. Additives such as fillers, metal powders, powders such as pigments, and particles can be blended. These can be used alone or in combination of two or more.
It is preferable that the tackifier is not substantially contained from the viewpoint of durability and transparency.

The adhesive for the adhesive layer of the present invention comprises the adhesive composition [I], that is, the adhesive composition [I] is cured.

In the adhesive, for example, when the initial adhesive force (α) is less than 1N / 25 mm and the time-dependent adhesive force (β) is adjusted to be 10 times or more the initial adhesive force (α), for example. , (1) In the raw material composition of the polyester resin (A), a method containing a large amount of aromatic polyvalent carboxylic acids (A1-1) among the polyvalent carboxylic acids (A1), (2) Polyester resin (A). ) In the raw material composition of the method containing a large amount of polyether glycol (A2-1) among the polyhydric alcohols (A2), (3) in the raw material composition of the polyester resin (A), the polyhydric alcohol (A2) Among them, a method in which a polyether glycol (A2-1) and an alkylene glycol (A2-2) are used in combination, (4) a combination of the above (1) and (2), (1) and (3), and the like can be mentioned. The method (4) is preferable in terms of adhesive performance.

It is preferable that the adhesive has substantially no acidic group, and specifically, the acid value is preferably 10 mgKOH / g or less, particularly preferably 5 mgKOH / g or less, and more preferably 5 mgKOH / g or less. It is 1 mgKOH / g or less, particularly preferably 0.5 mgKOH / g or less. The practical lower limit is 0 mgKOH / g.
The acid value of the adhesive can be determined by the same method as the acid value of the polyester resin (A).

The adhesive composition [I] used in the present invention can be used for bonding various members, and among them, it can be used as an adhesive for optical members used for bonding optical members. Preferably, the optical member with the adhesive layer can be obtained by laminating and forming the adhesive layer of the adhesive made of the adhesive composition [I] on the optical member.

Examples of such an optical member include an ITO electrode film, a transparent electrode film such as an inorganic or organic conductive film such as polythiophene, a polarizing plate, a retardation plate, an elliptical polarizing plate, an optical compensation film, a brightness improving film, an electromagnetic wave shielding film, and the like. Examples thereof include an electromagnetic wave absorbing film and an AR (anti-reflection) film. Among these, an ITO electrode film is particularly preferable because it is effective when the optical member is a transparent electrode film and high adhesive strength can be obtained. The ITO electrode film is often formed of a thin film on a substrate such as glass or PET, but in the present invention, it is possible to use a film in which the ITO electrode film is formed on a PET substrate. Especially preferable.
It is also suitable for a light extraction film provided on the light emitting surface of a surface light emitting body 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 adhesive layer is further provided with a release film on the surface opposite to the surface of the optical member of the adhesive layer, and when it is put into practical use, the release film is used. It is peeled off and the adhesive layer and the adherend are attached to each other. As such a release film, it is preferable to use a silicon-based release film.

Further, the adhesive sheet of the present invention is an adhesive sheet having an adhesive layer on one side or both sides of a supporting base material, and in particular, an optical member adhesive used for bonding optical members. Suitable as a sheet.
In the present invention, the term "sheet" is described as including "film" and "tape".

<Adhesive sheet>
The adhesive sheet can be produced, for example, as follows.
As a method for producing such an adhesive sheet, it can be produced according to a known general method for producing an adhesive sheet. For example, the adhesive composition [I] is coated on a substrate. The release sheet (or release film) is attached to the surface of the adhesive composition layer on the opposite side after drying, and the release sheet (or release film) is cured as necessary to form the adhesive composition [I] on the substrate. The adhesive sheet of the present invention having an adhesive layer can be obtained.

Alternatively, the above-mentioned adhesive composition [I] may be applied onto a release sheet, dried, and a base material may be attached to the opposite adhesive composition layer surface and cured if necessary. The adhesive sheet of the present invention can be obtained.

Further, a base material-less double-sided adhesive sheet can be manufactured by forming an adhesive layer on the release sheet and attaching the release sheet to the adhesive layer surface on the opposite side.

When the obtained adhesive sheet or base material-less double-sided adhesive sheet is used, the release sheet is peeled off from the adhesive layer and the adhesive layer and the adherend are bonded to each other.

Examples of the base material include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, borobutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; Polyfluoroethylene resin such as polyvinylidene polyfluoride and ethylene polyfluoride; polyamide such as nylon 6, nylon 6,6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl Vinyl polymers such as alcohol copolymers, polyvinyl alcohol and vinylon; cellulose-based resins such as cellulose triacetate and cellophane; acrylic resins such as methyl polymethacrylate, ethyl polymethacrylate, ethyl polyacrylate and butyl polyacrylate. Polystyrene; Polycarbonate; Polyallylate; Polyimide; Synthetic resin sheet such as cycloolefin polymer, metal foil of aluminum, copper, iron, high-quality paper, paper such as glassin paper, glass fiber, natural fiber, synthetic fiber, etc. Examples include non-woven fabrics. These base materials can be used as a single layer or as a multi-layer in which two or more kinds are laminated.

Among these, polyethylene terephthalate and a base material made of polyimide are particularly preferable, polyethylene terephthalate is particularly preferable because it has excellent adhesiveness to an adhesive, and polyethylene terephthalate (PET) having a metal thin film layer is preferable. However, the adhesive strength between the base material and the adhesive is excellent, and the base material can be kept stable without corroding the metal thin film layer, and the effect of the adhesive used in the present invention is remarkable. It is preferable in that it can be exerted.

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

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

The thickness of the base material is preferably, for example, 1 to 1000 μm, particularly preferably 2 to 500 μm, and even more preferably 3 to 300 μm.

As the coating method of the adhesive composition [I], 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 may be used. good.

As the conditions of the above curing treatment, the temperature is usually room temperature (23 ° C.) to 70 ° C., and the time is usually 1 to 30 days. Specifically, for example, at 23 ° C. for 1 to 20 days, preferably at 23 ° C. It may be carried out under conditions such as 3 to 14 days and 1 to 10 days at 40 ° C.

As the 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 1 to 5 minutes.

The thickness of the adhesive layer of the adhesive sheet and the base material-less double-sided adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 200 μm, and even more preferably 10 to 100 μm. If the thickness of the adhesive layer is too thin, the adhesive strength tends to decrease, and if it is too thick, it becomes difficult to apply the adhesive layer uniformly, and problems such as bubbles entering the coating film are likely to occur. Tend. When considering shock absorption, it is preferably 50 μm or more.

The thickness of the adhesive layer is a measured value of the thickness of the constituent members other than the adhesive layer from the measured value of the entire thickness of the adhesive sheet using "ID-C112B" manufactured by Mitutoyo. It is a value obtained by subtracting.

The gel fraction of the adhesive layer of the adhesive sheet is preferably 50% by weight or more, particularly preferably 60 to 92% by weight, and further preferably 70 to 70% by weight from the viewpoint of durability and adhesive strength. 90% by weight. If the gel fraction is too low, the cohesive force tends to decrease and the durability tends to decrease. If the gel fraction is too high, there is a concern that the adhesive strength will decrease due to the increase in cohesive force.

The gel fraction is a measure of the degree of cross-linking, and is calculated by, for example, the following method. That is, a pressure-sensitive adhesive sheet (without a release film) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, polyethylene terephthalate film) as a base material is formed by a 200-mesh SUS wire mesh. Wrapped and immersed in toluene at 23 ° C. for 24 hours, the weight percentage of the insoluble adhesive adhesive component remaining in the wire mesh is defined as the gel fraction. However, the weight of the base material is deducted.

Further, the adhesive sheet may be protected by providing a release film on the outside of the adhesive layer, if necessary. Further, in the adhesive sheet in which the adhesive layer is formed on one side of the base material, the peeled surface is removed by performing a peeling treatment on the surface opposite to the adhesive layer of the base material. It can also be utilized to protect the adhesive layer.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the example, "part" and "%" mean the weight standard.
Further, the weight average molecular weight and the glass transition temperature of the polyester resin in the following examples were measured according to the above-mentioned method. The acid value of the polyester resin was measured by dissolving 0.5 g of the polyester resin in a mixed solvent of 7/3 (weight ratio) (toluene / methanol) and performing neutralization titration based on JIS K0070.

<Manufacturing of polyester resin (A)>
The moles described in the following production examples indicate the molar ratio when the total amount of the polyvalent carboxylic acids (A1) is 1.0 mol.

[Manufacturing of polyester resin (A-1)]
15.5 parts (1.0 mol) of isophthalic acid as polyhydric carboxylic acids (A1) in a reaction can equipped with a heating device, a thermometer, a stirrer, a rectification tower, a nitrogen introduction tube and a vacuum device. As alcohol (A2), 2.9 parts (0.5 mol) of ethylene glycol, 80.4 parts (0.9 mol) of polytetramethylene ether glycol (PTG-L1000, manufactured by Hodoya Chemical Co., Ltd.), 1 methylol propane. .2 parts (0.1 mol), 0.01 part of tetrabutyl titanate as a catalyst was charged, the temperature was gradually raised to an internal temperature of 250 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 ° C., 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polycondensation reaction was carried out over 3 hours to produce a polyester resin (A-1). ..
The obtained polyester resin (A-1) has a weight average molecular weight of 97,000, a glass transition temperature of −69 ° C., an acid value of 0.8 mgKOH / g, and a finished component ratio of polyvalent carboxylic acids (A1). Isophthalic acid was 100 mol%, and ethylene glycol / polytetramethylene ether glycol / trimethylolpropane = 6.1 mol% / 89.8 mol% / 4.1 mol% as polyhydric alcohol (A2).

[Manufacturing of polyester resin (A-2)]
14.3 parts (1.0 mol) of isophthalic acid as polyhydric carboxylic acids (A1), polyvalent in a reaction can equipped with a heating device, thermometer, stirrer, rectification tower, nitrogen introduction tube and vacuum device. As alcohol (A2), 5.3 parts (1.0 mol) of ethylene glycol, 80.0 parts (0.97 mol) of polytetramethylene ether glycol (PTG-L1000, manufactured by Hodoya Chemical Co., Ltd.), 0 trimethylolpropane. .3 parts (0.03 mol), 0.01 part of tetrabutyl titanate as a catalyst was charged, the temperature was gradually raised to an internal temperature of 250 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 260 ° C., 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce a polyester resin (A-2).
The obtained polyester resin (A-2) had a weight average molecular weight of 45,000, a glass transition temperature of −70 ° C., and an acid value of 0.4 mgKOH / g. The finished component ratio is 100 mol% of isophthalic acid as the polyhydric carboxylic acid (A1) and ethylene glycol / polytetramethylene ether glycol / trimethylolpropane = 2.2 mol% / 96.8 mol as the polyhydric alcohol (A2). It was% / 1.0 mol%.

[Manufacturing of polyester resin (A'-1)]
9.6 parts (0.2 mol) of isophthalic acid and sebacic acid as polyhydric carboxylic acids (A1) in a reaction can equipped with a heating device, a thermometer, a stirrer, a rectification tower, a nitrogen introduction tube and a vacuum device. 46.8 parts (0.8 mol), as polyhydric alcohol (A2), 27.1 parts (0.9 mol) of neopentyl glycol, 13.0 part (0.5 mol) of 1,4-butanediol, Add 3.0 parts (0.087 mol) of 1,6-hexanediol, 0.5 part (0.013 mol) of trimethylolpropane, and 0.01 part of tetrabutyl titanate as a catalyst, and gradually increase the internal temperature to 250 ° C. The temperature was raised to 4 hours and the esterification reaction was carried out. Then, the internal temperature was raised to 260 ° C., 0.01 part of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and the polymerization reaction was carried out over 3 hours to produce a polyester resin (A'-1). .. The obtained polyester resin (A'-1) had a weight average molecular weight of 70,000, a glass transition temperature of −50 ° C., and an acid value of 0.4 mgKOH / g.

<Hydrolysis inhibitor (B)>
The following were prepared as the hydrolysis inhibitor (B).
(B-1) Carbodiimide group-containing hydrolysis inhibitor (Nisshinbo Chemical Co., Ltd., Carbodilite V-07, Carbodiimide equivalent 200)

<Crosslinking agent (C)>
The following were prepared as the cross-linking agent (C).
(C-1) Trimer of isocyanurate of hexamethylene diisocyanate (Colonate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.)

<Catalyst (D)>
The following catalysts (D) were prepared.
(D-1) Dibutyl phthalate laurilate (DBTL)
(D-2) Zirconium Tetraacetylacetonate (manufactured by Matsumoto Fine Chemicals, ZC-150)

<Antioxidant (E)>
The following items were prepared as the antioxidant (E).
(E-1) Hindert Phenolic Antioxidant (BASF, Ilganox 1010)

(Examples 1 to 4, comparative examples 1 to 3)
The polyester resin obtained above is diluted with ethyl acetate to a solid content concentration of 50%, and each component is blended with 200 parts of this polyester resin solution (solid content 100 parts) as shown in Table 1 below. , Stirring and mixing to obtain a polyester-based adhesive composition. The numbers in the table indicate the number of copies in terms of solid content.
Using the obtained polyester-based adhesive composition, evaluation was performed as follows.

<Manufacturing of adhesive sheet with release film>
The polyester-based adhesive compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were each applied on a 100 μm-thick polyethylene terephthalate (PET) film using an applicator and at 100 ° C. for 3 minutes. It was dried to form a pressure-sensitive adhesive composition layer (thickness 25 μm), and then the surface of the obtained pressure-sensitive adhesive composition layer was covered with a release-treated PET film (release film) at 40 ° C. After aging treatment for 4 days, a sticky adhesive sheet with a release film was obtained.

Using the adhesive sheet with a release film, the gel fraction and the adhesive strength under each condition were evaluated. The results are summarized in Table 1 below.

[Gel fraction (%)]
The release film of the 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 viscous residue remaining in the wire mesh. The weight percentage of the adhesive component was determined as the gel fraction. However, the weight of the base material was subtracted.

[Adhesive strength (N / 25 mm)]
<Initial adhesive strength (α)>
The release film-attached adhesive sheet obtained above is cut into a size of 25 mm × 150 mm as a measurement sample, the release film is peeled off, and the adhesive layer side of the release film is heated at 23 ° C., 50. A 2 kg roller is reciprocated on a glass plate (soda glass) under% RH environment to apply pressure, and after leaving it at 23 ° C for 30 minutes under 50% RH environment, Autograph (manufactured by Shimadzu Corporation, "Autograph AGS" -H 500N ") was used to measure the 180-degree peeling strength (N / 25mm) at a peeling speed of 300 mm / min to determine the adhesive strength.

<Adhesive strength over time (β)>
Peel off the release film of the release film with the release film obtained above, and put the adhesive layer side of the release film on a glass plate (soda glass) at 23 ° C and 50% RH environment. The roller is reciprocated to apply pressure, heat it in a 50 ° C environment for 5 days, then return it to a 23 ° C, 50% RH environment, leave it for 30 minutes, and then autograph (manufactured by Shimadzu Corporation, "Autograph AGS". -H 500N ") was used to measure the 180-degree peeling strength (N / 25mm) at a peeling speed of 300 mm / min to determine the adhesive strength.

<Adhesive strength over time (γ)>
Peel off the release film of the release film with the release film obtained above, and put the adhesive layer side of the release film on a glass plate (soda glass) at 23 ° C and 50% RH environment. After applying pressure by reciprocating the rollers and leaving it in a 50% RH environment at 23 ° C for 2 days, a peeling speed of 300 mm / using an autograph (manufactured by Shimadzu Corporation, "Autograph AGS-H 500N"). The adhesive strength was determined by measuring the 180-degree release strength (N / 25 mm) in min.

From the results in Table 1 above, the adhesive sheets of Examples 1 to 4 had a low initial adhesive force (α) and had an adhesive force sufficient to be reattached, and then heated in an environment of 50 ° C. for 5 days. The later adhesive strength (β) with time was 10 times or more stronger than the initial adhesive strength (α).
On the other hand, in Comparative Examples 1 and 3, the initial adhesive strength (α) was low and the adhesive strength was such that the adhesive could be reattached, but the adhesive strength over time (β) after heating was not strong adhesiveness. It showed only about 5 times the initial adhesive strength (α). Further, Comparative Example 2 shows an initial adhesive force (α) of 2.5 N / 25 mm, which makes it difficult to reattach, while the adhesive force over time (β) after heating is the initial adhesive force (α). It showed only about 5 times the adhesive strength of.

Further, in Examples 1 to 4, even with the time-dependent adhesive strength (γ) in a state where the initial environmental conditions (23 ° C. × 50% RH) were continued for 2 days, the adhesive strength was low enough to be reattached. On the other hand, the adhesive force with time (β) after heating showed a strong adhesive force of 5 times or more with the adhesive force with time (γ).

The adhesive sheet of the present invention has low adhesive strength at room temperature, can be temporarily fixed to the extent that it can be reattached, becomes strongly adhesive when heated, and firmly adheres to the adherend, or firmly adheres to each other. Since it is an adhesive sheet that can be bonded, it can be suitably used for bonding optical members for bonding a display, optical components constituting the display, and the like.

Claims (8)

An adhesive layer comprising the adhesive composition [I] containing a polyester resin (A) and a hydrolysis inhibitor (B) .
When the adhesive layer is formed on the substrate and forms an adhesive sheet together with the substrate,
A viscous adhesive layer characterized in that the following initial adhesive force (α) is less than 1N / 25 mm, and the following aging adhesive force (β) is 10 times or more the initial adhesive force (α).
Initial adhesive strength (α): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate under a 23 ° C. and 50% RH environment by reciprocating a 2 kg roller, and then pressed and attached under a 23 ° C. and 50% RH environment. Adhesive strength measured at 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min using an autograph after being left for 30 minutes.
Adhesive strength over time (β): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate at 23 ° C in a 50% RH environment by reciprocating a 2 kg roller, and heated in a 50 ° C environment for 5 days. Then, after returning to the environment of 23 ° C. and 50% RH and leaving for 30 minutes, the adhesive strength measured by 180 degree peeling strength (N / 25 mm) at a peeling speed of 300 mm / min using an autograph. The adhesive according to claim 1, wherein the following adhesive force over time (γ) is 1 N / 25 mm or less, and the adhesive force over time (β) is 5 times or more the adhesive force over time (γ). layer.
Adhesive strength over time (γ): The adhesive layer side of the adhesive sheet is pressure-bonded to a glass plate under a 23 ° C, 50% RH environment by reciprocating a 2 kg roller, and under a 23 ° C, 50% RH environment. Adhesive strength measured at 180 degree peel strength (N / 25 mm) at a peel speed of 300 mm / min using an autograph after being left in the water for 2 days. The polyhydric carboxylic acid (A1) and the polyhydric alcohol (A2) are contained as the constituent raw materials of the polyester resin (A), and the polyhydric alcohol (A2) contains the polyether glycol (A2-1). The viscous adhesive layer according to claim 1 or 2. The adhesive layer according to claim 3, wherein the polyhydric alcohol (A2) contains an alkylene glycol (A2-2). The adhesive layer according to claim 3 or 4, wherein the polyvalent carboxylic acid (A1) contains an aromatic polyvalent carboxylic acid (A1-1). The adhesive layer according to any one of claims 1 to 5 , wherein the adhesive composition [I] further contains a cross-linking agent (C). The adhesive layer according to any one of claims 1 to 6 , wherein the adhesive layer is used for bonding optical members. A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to any one of claims 1 to 7 .