JP2001192634A - Photosetting type adhesive composition and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photo-setting type adhesive composition that shows the pressure-sensitive adhesion at ordinary temperature, is cured by irradiation with activated energy lines, has high adhesion to the substrate of high polarity, for example, PET, PVC or the like with excellent humid heat-resistant adhesion, and provide the adhesive sheet obtained from the adhesive composition. SOLUTION: This photo-setting type adhesive composition comprises a polyester resin, a photo-cationically polymerizing compound and a photo-cationic polymerization initiator in which the polycarboxylic acid components constituting the polyester resin are aromatic ring-bearing polycaboxylic acids. There are also provided adhesive sheets from the adhesive composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet which normally have a pressure-sensitive adhesive property and are cured by irradiating light.

[0002]

2. Description of the Related Art A photo-curable pressure-sensitive adhesive composition that has the characteristics of a pressure-sensitive adhesive and an adhesive, can be used like a pressure-sensitive adhesive at the time of lamination, and starts to be hardened by light to exhibit strong bonding strength. Flat 10-508636
Discloses an adhesive containing a free radical polymerizable polymer, a cationic photopolymerizable monomer, and a photoactive catalyst. However, when a typical acrylic resin is used as the free-radical polymerized polymer, polyethylene terephthalate (PET), polyvinyl chloride (PVC) is used as the adherend.
In addition, the adhesive strength of a metal or the like after being cured to an adherend is insufficient, and therefore, when attempting to adhere to these adherends, the adhesion reliability has been reduced.

[0003] In order to improve the adhesion to PET, PVC, metal and the like, it is conceivable to use a polyester resin. However, the polyester resin may lose its adhesion due to hydrolysis of the ester under high temperature and high humidity conditions. Yes, there were concerns about adhesion reliability.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention exhibits pressure-sensitive adhesive properties at room temperature, is cured by irradiation with active energy rays, and has a high polarity coating such as PET or PVC. It is an object of the present invention to provide a photocurable pressure-sensitive adhesive composition having good adhesion to a body and excellent moisture-heat resistance, and a pressure-sensitive adhesive sheet obtained from the composition.

[0005]

The polyester resin is basically a polycondensate of a polyhydric carboxylic acid and a polyhydric alcohol, and the polyester resin used for adhesives and adhesives is flexible and flexible. In general, an aromatic ring-containing polycarboxylic acid and an aliphatic polycarboxylic acid are used in combination as polycarboxylic acids due to the requirement of properties and the like. As a polyvalent carboxylic acid, without using an aliphatic polyvalent carboxylic acid, it was found that by using a polyester resin using only an aromatic ring-containing polyvalent carboxylic acid, the moist heat resistance was improved, which led to the present invention. . The present invention is a photocurable pressure-sensitive adhesive composition comprising a polyester resin, a cationic photopolymerizable compound, and a cationic cationic polymerization initiator, wherein the polyvalent carboxylic acid component constituting the polyester resin contains an aromatic ring-containing polyvalent. A photocurable pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet, which are carboxylic acids.

The aromatic ring-containing polycarboxylic acid is not particularly limited as long as it is a polyvalent carboxylic acid having an aromatic ring in the molecule, and a carboxyl group may be directly bonded to the aromatic ring. May be bonded via another group such as a methylene group. Among the aromatic ring-containing polycarboxylic acids, an aromatic polycarboxylic acid in which a carboxyl group is directly bonded to an aromatic ring is preferable from the viewpoint of adhesiveness, heat and moisture resistance, and, specifically, for example, terephthalic acid, Dicarboxylic acids such as isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid and sodium sulfoisophthalate;
Trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid are exemplified. These aromatic polycarboxylic acids are appropriately selected and used in accordance with the required properties of the polyester, and may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include diols such as ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol, and trimethylolpropane. And trihydric or higher alcohols such as pentaerythritol, and polyether polyhydric alcohols having a hydroxyl group at a terminal. In the present invention, since only an aromatic ring-containing polycarboxylic acid is used as the polycarboxylic acid, in order to improve the flexibility of the polyester resin, a straight chain having many carbon atoms is used as the polyhydric alcohol component. It is preferred to use alcohol. These polyhydric alcohols are appropriately selected and used depending on the required properties of the polyester resin, and may be used alone,
Two or more kinds may be used in combination.

[0008] The molecular weight of the polyester resin is not particularly limited, but usually those having a molecular weight of 10,000 to 50,000 are preferably used. The method for synthesizing the polyester resin is as follows:
It is not particularly limited, and is synthesized by a general polycondensation method generally used.

The photocationically polymerizable compound in the present invention may be any compound having at least one photocationically polymerizable functional group in the molecule, and is not particularly limited. Compounds having one photocationically polymerizable functional group such as one epoxy group, oxetane group, hydroxyl group, vinyl ether group, episulfide group, ethyleneimine group and the like can be mentioned.

The molecular weight of the cationic photopolymerizable compound used in the present invention is not particularly limited, and may be any of a monomer, an oligomer, and a polymer. The above cationic photopolymerizable compounds may be used alone or in combination of two or more.

As the cationic photopolymerizable compound, an epoxy group-containing compound having at least one epoxy group in a molecule is more preferably used. The epoxy group-containing compound is not particularly limited, and examples thereof include bisphenol A epoxy resins, bisphenol F epoxy resins such as bisphenol F epoxy resins, phenol novolak epoxy resins, cresol novolak epoxy resins, and glycidyl. Bifunctional or higher functional epoxy resins such as an ether type epoxy resin and a glycidylamine type epoxy resin are exemplified.

Other examples of the epoxy group-containing compound include, for example, "Epicoat 1001" and "Epicoat 10".
A commercially available product such as "02" (both manufactured by Yuka Shell Epoxy) may be used. Further, for example, an addition polymer of an epoxy monomer or an epoxy oligomer such as glycidylated polyester, glycidylated polyurethane, or glycidylated acryl may be used. In particular, when the polyester resin has a high glass transition point, a flexible epoxy resin can be used to impart appropriate flexibility to the cured resin. Specifically, for example, “Rica Resin BPO-20E”, “Rica Resin BEO-60E”
(Above, manufactured by Shin Nippon Rika Co., Ltd.). The epoxy group-containing compound may be used alone or in combination of two or more.

The amount of the cationically polymerizable compound is preferably from 10 to 100 parts by weight based on 100 parts by weight of the polyester resin. When the amount of the cationic photopolymerizable compound is 10
If it exceeds 0 parts by weight, the adhesion to PET, PVC, metal, etc. tends to decrease, and if it is less than 10 parts by weight,
The proportion of the cross-linking component due to cationic polymerization may decrease, and the heat resistance after curing may decrease.

The cationic photopolymerization initiator in the present invention may be of an ionic photoacid generating type or a nonionic photoacid generating type. The ionic photoacid generation type photocationic polymerization initiator is not particularly limited, but, for example, onium salts such as aromatic diazonium salts, aromatic halonium salts, aromatic sulfonium salts, and iron-allenes And organometallic complexes such as a complex, a titanocene complex, and an arylsilanol-aluminum complex. These cationic photopolymerization initiators may be used alone or in combination of two or more.

Specific examples of the above-mentioned ionic photoacid generating type cationic photopolymerization initiator are not particularly limited. For example, "Adeka Optomer SP150",
Commercial sound ratios such as "ADEKA OPTOMER SP170" (above, manufactured by Asahi Denka Kogyo), "UVE-1014" (manufactured by General Electronics), and "CD-1012" (manufactured by Sartomer) may be used.

Examples of the nonionic photoacid generating type cationic photopolymerization initiator include, but are not particularly limited to, nitrobenzyl esters, sulfonic acid derivatives, phosphoric acid esters, phenolsulfonic acid esters, and the like. Examples thereof include diazonaphthoquinone and N-hydroxyimidosulfonate. These may be used alone or in combination of two or more.

The amount of the cationic photopolymerization initiator is not particularly limited, but is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the cationic photopolymerizable compound. When the amount of the cationic polymerization initiator is less than 0.1 part by weight,
Photocation polymerization may not proceed sufficiently or the reaction may be too slow. If the amount exceeds 10 parts by weight, the reaction may be too fast, resulting in a decrease in workability or a non-uniform reaction.

In the present invention, light is used as an activation energy beam applied to activate the above-mentioned cationic photopolymerization initiator. The activation energy ray is not particularly limited, but includes, for example, microwaves, infrared rays, visible light, ultraviolet rays, X-rays, γ-rays, etc., and is particularly easy to handle and has a relatively high energy. Ultraviolet rays that can be obtained are more preferably used. Particularly preferably, ultraviolet light having a wavelength of 200 to 400 nm is used. The ultraviolet rays are irradiated using an appropriate light source such as a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, and a xenon lamp.

The method for producing the photocurable pressure-sensitive adhesive composition is as follows:
Not special, homodisper, homomixer,
Using a mixer such as a universal mixer, a planetarium mixer, a kneader, or a three-roll, at room temperature or under heating,
By mixing predetermined amounts of the polyester resin, the cationic photopolymerizable compound and the cationic photopolymerization initiator, a desired photocurable pressure-sensitive adhesive composition can be obtained. The production of the photocurable pressure-sensitive adhesive composition is desirably performed in a state where light is blocked.

The thus obtained photocurable pressure-sensitive adhesive composition of the present invention may be applied as it is to one or both surfaces of a bonding member (adherend), photo-cationically polymerized and cured. In order to obtain good handling workability and simplicity, it is preferable to use a photocurable pressure-sensitive adhesive sheet which has been processed into a sheet shape in advance. The pressure-sensitive adhesive sheet is usually preferably a double-sided pressure-sensitive adhesive sheet, but may be a single-sided pressure-sensitive adhesive sheet in some cases.

The thickness of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably from 1 to 2000 μm, more preferably from 10 to 1000 μm. If the thickness of the pressure-sensitive adhesive sheet itself is less than 1 μm, the adhesiveness of the pressure-sensitive adhesive sheet may be affected by surface irregularities of the joining member, and if the thickness exceeds 2000 μm, the curing time may be excessively long. There is.

The method of processing the above-mentioned pressure-sensitive adhesive sheet is not particularly limited. For example, a bar coating method, a roll coating method, a gravure coating method,
It is coated by various coating methods such as an extrusion coating method and formed into a sheet. During the sheeting process, the photocurable pressure-sensitive adhesive composition is solid, or semi-solid, or has a high viscosity even in a liquid state and is difficult to apply, for example, diluted with an organic solvent. Alternatively, the viscosity may be reduced by heating and melting. Since the sheet-form photocurable pressure-sensitive adhesive sheet is pressure-sensitive at room temperature, it is preferable that the surface is protected with a release sheet such as polyethylene, for example, so as to be easily handled, and a desired pressure-sensitive adhesive sheet is wound up.

The support and the release sheet are not particularly restricted but include, for example, polyethylene terephthalate, polyethylene naphthalate, polyethylene,
Examples include polypropylene, polycarbonate, nylon, polyarylate, polysulfone, polyethersulfone, polyetheretherketone, polyphenylenesulfite, polystyrene, polyacryl, polyvinyl acetate, triacetylcellulose, diacetylcellulose, cellophane, and the like. The support and the release sheet are not particularly limited, but preferably have a thickness of 10 μm or more. When the thickness is less than 10 μm, the strength may be low, so that the support or the release sheet may be broken during use.

[0024] In the joining method using the photocurable pressure-sensitive adhesive composition, the activation energy beam is applied to the photocurable pressure-sensitive adhesive composition at a time when the light-curable pressure-sensitive adhesive composition is coated. Before or after joining with the substrate. For example, when at least one of the joining members is light-transmissive, the photocurable pressure-sensitive adhesive composition or the photocurable pressure-sensitive adhesive sheet is applied or attached to at least one of the joining members, and then joined to the other joining member. Then, activation energy is given by irradiating light from the surface of the light-transmissive joining member, and the photocurable pressure-sensitive adhesive composition or the photocurable pressure-sensitive adhesive sheet is photocationically polymerized and cured. In the case of this method, it is desirable to apply activation energy as soon as possible after the joining members are joined in order to reduce the time of the entire joining process. Also,
At the time of joining, in order to improve the adhesion, it is possible to heat and join with the joining member.

When both of the joining members are not light-transmitting, a photocurable pressure-sensitive adhesive composition or a light-postcurable pressure-sensitive adhesive sheet is applied or attached to at least one of the joining members.
Then, after applying activation energy by irradiating the pressure-sensitive adhesive composition or the pressure-sensitive adhesive sheet surface with light,
What is necessary is just to join with the other joining member, to carry out photocationic polymerization of the photocurable pressure-sensitive adhesive composition or photocurable pressure-sensitive adhesive sheet, and to cure it. In the case of this method, in order to smoothly join one joining member and the other joining member, the joining of the two joining members is performed as quickly as possible after activation energy is applied, preferably within 10 minutes. It is desirable to do.

In any of the above methods, the curing of the photocurable pressure-sensitive adhesive composition or photocurable pressure-sensitive adhesive sheet by the photocationic polymerization reaction proceeds at room temperature in a short time, and the cured product has excellent adhesive strength and solvent resistance. Develop heat resistance and water resistance. Further, in order to further promote the curing reaction of the photocurable pressure-sensitive adhesive composition or the photocurable pressure-sensitive adhesive sheet and further shorten the curing time, other curing means such as heating together with the application of the activation energy by the light irradiation are used in combination. May be.

(Function) The photocurable pressure-sensitive adhesive composition of the present invention contains a polyester resin, a photocationic polymerizable compound, and a photocationic polymerization initiator and exhibits pressure sensitivity at room temperature, so that it can be easily applied. By irradiating light, the curing reaction of the cationic photopolymerizable compound proceeds, a crosslinked structure is formed, and the polyester resin is incorporated therein, so that high adhesive strength is exhibited. Further, the photocurable pressure-sensitive adhesive composition of the present invention contains a polyester resin using an aromatic ring-containing polyvalent carboxylic acid as the polyvalent carboxylic acid, and thus has excellent adhesiveness and wet heat resistance.

[0028]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 [Adjustment of pressure-sensitive adhesive composition] Polyester resin (terephthalic acid 25 mol%, isophthalic acid 25 mol%, ethylene glycol 25 mol%, neopentyl glycol 25 mol%
Was obtained by polycondensation according to a conventional method. ) 65 parts by weight, epoxy resin (Rica Resin BEO60E, manufactured by Shin Nippon Rika Co., Ltd.) 35
Parts by weight, cationic photopolymerization initiator (ADEKA OPTOMER SP
170, manufactured by Asahi Denka Co., Ltd.) 1 part by weight, methyl ethyl ketone 1
Using 50 parts by weight of a homodisper type stirring mixer (Homodisper L type, manufactured by Tokushu Kika Co., Ltd.), the stirring speed was 3000 r.
By stirring and mixing uniformly at pm, a photocurable pressure-sensitive adhesive composition was prepared. [Preparation of pressure-sensitive adhesive sheet] Using the obtained photocurable pressure-sensitive adhesive composition, on a 50-μm-thick PET film subjected to a release treatment, the thickness after coating with a bar coater was 100 μm.
And dried to obtain a photocurable pressure-sensitive adhesive sheet. Next, a PET protective film subjected to a silicone release treatment was laminated on the surface of the pressure-sensitive adhesive composition of the obtained photocurable pressure-sensitive adhesive sheet to produce a photocurable pressure-sensitive adhesive sheet.

[Preparation of bonded article] PET obtained by subjecting a photocurable pressure-sensitive adhesive sheet to a corona treatment while peeling off a protective film
Laminator surface temperature of 12 on the corona treated surface of the film
Heat lamination was performed at 0 ° C. Next, the release PET film was peeled off, and the amount of ultraviolet light having a wavelength of 365 nm was applied to the surface of the pressure-sensitive adhesive composition of the photocurable pressure-sensitive adhesive sheet using an ultra-high pressure mercury lamp at an irradiation amount of 2 nm.
Immediately after the irradiation at 400 mJ / cm ² , the adhesive composition surface was heated and laminated at 120 ° C. on the corona-treated surface of a PET film having the same corona-treated surface to produce a joined body.

Comparative Example 1 Polyester resin containing aliphatic polycarboxylic acid (UE34)
00, manufactured by Unitika Ltd.) 65 parts by weight, epoxy resin (Rica Resin BEO60E, manufactured by Shin Nippon Rika Co., Ltd.) 35 parts by weight, photocationic polymerization initiator (ADEKA OPTOMER SP270, manufactured by Asahi Denka Co., Ltd.) 1 part by weight, methyl ethyl ketone 150 parts by weight In the same steps as in Example 1, a photocurable pressure-sensitive adhesive sheet was prepared, and the obtained photocurable pressure-sensitive adhesive sheet was used to obtain a light-curable pressure-sensitive adhesive sheet according to Example 1.
A joined body was produced in the same manner as described above.

[Evaluation] The obtained joined body was heated at 110 ° C. for 3 hours.
After being placed in an oven for 0 minutes and cured, the adhesive strength was measured and defined as the initial adhesive strength. The joined body after curing is 85 ° C.
It was put into a constant temperature and humidity oven of 95% RH, and the adhesive strength after 3 days was measured to obtain the wet heat adhesive strength. The adhesive strength is
The joined body was cut to a width of 10 mm, and a T-type peel test was performed at a peel speed of 50 mm / min using a Tensilon type tensile tester. Table 1 shows the results.

[0032]

[Table 1]

From the above results, it was found that the use of the polyester resin using the aromatic ring-containing polycarboxylic acid improved the wet heat resistance.

[0034]

The photo-curable pressure-sensitive adhesive composition of the present invention is a photo-curable pressure-sensitive adhesive composition comprising a polyester resin, a photo-cationic polymerizable compound and a photo-cationic polymerization initiator, wherein the polyester resin is aromatic. Since it is made of a ring-containing polycarboxylic acid, it has excellent adhesion strength to PET, PVC, and the like, and also excellent moisture-heat resistance.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J004 AA15 AA17 AB07 CA02 CA03 CA04 CA06 CC02 DB03 EA05 4J040 DF041 DF042 EC061 EC062 EC071 EC072 EC121 EC122 ED041 ED091 ED161 ED162 EF001 EF002 FA151 FA152 GA11 H09B08 HD44 LA01 LA06 LA07 LA08 PA32

Claims (2)

[Claims] 1. A photocurable pressure-sensitive adhesive composition comprising a polyester resin, a cationic photopolymerizable compound, and a cationic cationic polymerization initiator, wherein the polyvalent carboxylic acid component constituting the polyester resin is an aromatic ring-containing polyvalent component. A photocurable pressure-sensitive adhesive composition, which is a carboxylic acid. 2. A pressure-sensitive adhesive sheet comprising the photocurable pressure-sensitive adhesive composition according to claim 1.