JP3281026B2 - Radiation-curable hot pressure-sensitive adhesive and its adhesive tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-curable hot pressure-sensitive adhesive which exhibits strong adhesive strength when heated at a low temperature for a short time.
And an adhesive tape using the same.

[0002]

2. Description of the Related Art Heretofore, there has been known a pressure-sensitive adhesive in which a hot-melt resin is mixed with a pressure-sensitive adhesive exhibiting strong adhesive strength at room temperature to improve the holding power such as creep characteristics (JP-B-56-130).
No. 40). However, it is necessary to dissolve it in a large amount of an organic solvent and process it into an adhesive tape or the like, and there is a problem that there are difficulties in environmental hygiene and safety.

On the other hand, a radiation-curable pressure-sensitive adhesive has been proposed which is a solvent-free coating type which can be applied with no solvent or with a small amount of solvent in response to the demand for reducing the amount of solvent used as described above. Such a radiation-curable pressure-sensitive adhesive has an advantage of being superior in water resistance and heat resistance as compared with emulsion-type and hot-melt-type adhesives. However, in conventional radiation-curable pressure-sensitive adhesives, those having a low molecular weight of the base polymer and a solventless coating type have a low cohesive force, have poor holding power, and have been diluted with a reactive monomer. Solvent-free coatings have the problem of poor adhesion.

[0004] Further, when a heat-fusible resin is added to a conventional radiation-curable pressure-sensitive adhesive, there has been a problem that the crosslinking treatment by radiation is inhibited and the cohesive strength is reduced. Therefore, in any case, it is difficult to satisfy both the adhesive force and the holding force while satisfying the solventless coating.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to develop a radiation-curable pressure-sensitive adhesive or adhesive tape which is a solvent-free coating type and has excellent adhesive strength and holding power.

[0006]

Means for Solving the Problems The present invention has a general formula: C
50% by weight of an acrylic monomer unit represented by H ₂ ＣC (R ¹ ) COOR ² (where R ¹ is hydrogen or a methyl group, and R ² is an alkyl group having 2 to 14 carbon atoms).
100 parts by weight of the acrylic polymer contained above, and 50 to 150 parts by weight of a hot-melt resin having a melting point of 70 to 200 ° C,
It contains 1 to 30 parts by weight of a polyfunctional monomer having two or more radiation-reactive unsaturated bonds in a molecule, and is hardened by irradiation.
To show adhesive strength, and the adhesive strength is larger by heat treatment
Solvent-free type radiation-curable hot pressure-sensitive adhesive characterized by exhibiting the following characteristics, and a radiation-curable hot-pressure-sensitive adhesive coating layer cured by irradiation with radiation.
The present invention provides an adhesive tape characterized by having a layer comprising a support on one or both sides of a support.

[0007]

The above composition makes it possible to obtain a solventless coating type hot pressure-sensitive adhesive which can be coated with no solvent or a small amount of solvent. Such a hot pressure-sensitive adhesive is cured by irradiation with radiation, exhibits weak adhesive strength at room temperature before heat treatment that can be easily re-applied and position corrected, and exhibits strong adhesive strength by heating. And excellent adhesion properties.

[0008]

Illustrative constituents of the invention The radiation-curable hot pressure-sensitive adhesive of the solventless coating type according to the present invention has the general formula: CH ₂ ＣC
(R ¹ ) COOR ² (where R ¹ is hydrogen or a methyl group, R ² is an alkyl group having 2 to 14 carbon atoms) An acrylic monomer containing 50% by weight or more of an acrylic monomer unit. A polymer is used as a component. An acrylic polymer that can be preferably used from the viewpoint of adhesive properties such as cohesive force and solvent-free coating properties has a weight average molecular weight of 50,000 to 400,000, especially 1
The number is between 100,000 and 300,000.

Specific examples of the above-mentioned acrylic monomer unit include alkyl groups such as ethyl group, propyl group, butyl group, isobutyl group, isoamyl group, hexyl group, 2-ethylhexyl group, isooctyl group, isononyl group and isodecyl group. And esters of acrylic acid and methacrylic acid having

[0010] The acrylic polymer may be prepared using 50 to 100% by weight of one or more acrylic monomers. Examples of other monomer units that the acrylic polymer may contain for adjustment of adhesive properties, such as acrylic acid, methacrylic acid, acrylamide,
Methacrylamide, acrylonitrile, vinyl acetate, styrene, N-vinylpyrrolidone, N-methylolacrylamide, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, methacryl And 2-hydroxypropyl acid.

The acrylic polymer may have a radiation-reactive unsaturated bond for the purpose of improving crosslinkability and the like.
The introduction of the radiation-reactive unsaturated bond is, for example, a hydroxyl group or a carboxyl group in an acrylic polymer,
A method of reacting a monomer having a functional group capable of reacting with a functional group such as an amino group and a radiation-reactive unsaturated bond, for example, glycidyl acrylate, glycidyl methacrylate, 2-methacryloyloxyethyl isocyanate with an acrylic polymer, Alternatively, it can be carried out by a method of preparing an acrylic polymer by a radical polymerization method using a compound having two or more radical-reactive or radiation-reactive unsaturated bonds in combination.

The radiation-curable hot pressure-sensitive adhesive of the present invention comprises:
A hot-melt resin having a melting point of 70 to 200 ° C is used as a component. When the melting point is less than 70 ° C., the obtained adhesive has poor heat resistance, and when it exceeds 200 ° C., the obtained adhesive has poor adhesive strength at low temperature heating. Hot-melt resins that can be preferably used include rosin-based resins, coumarone-indene-based resins, terpene-based resins, and petroleum-based resins. The hot-melt resin is
One or more kinds may be used.

Specific examples of the rosin resin include rosin esters, hydrogenated rosin esters, disproportionated rosin esters, and polymerized rosin esters. Specific examples of the coumarone-indene resin include a coumarone-indene resin, a hydrogenated coumarone-indene resin, a phenol-modified coumarone-indene resin, an epoxy-modified coumarone-indene resin, and the like. Specific examples of the terpene-based resin include a polyterpene resin, a styrene-modified terpene resin, and a phenol-modified terpene resin. Specific examples of petroleum resins include aliphatic petroleum resins, aromatic petroleum resins,
An aromatic modified aliphatic petroleum resin, an aromatic pure monomer resin and the like can be mentioned.

The amount of the hot-melt resin is 50 to 150 parts by weight per 100 parts by weight of the acrylic polymer. If the amount is less than 50 parts by weight, the resulting adhesive will have poor adhesion, and if it exceeds 150 parts by weight, the obtained adhesive will have poor wettability to the adherend.

The radiation-curable hot pressure-sensitive adhesive of the present invention comprises:
A polyfunctional monomer having two or more kinds of one or more kinds of radiation-reactive unsaturated bonds which can be crosslinked (cured) by irradiation with radiation, such as a vinyl group, an acryloyl group, a methacryloyl group, and a vinylbenzyl group in a molecule. Ingredients. Preferred polyfunctional monomers have an acryloyl group and / or a methacryloyl group. When the number of the radiation-reactive unsaturated bonds is less than 2, it is difficult to balance the adhesive properties such as the holding power and the adhesive strength of the obtained adhesive. In addition, generally, those containing 10 or less radiation-reactive unsaturated bonds are used, but the present invention is not limited to this.

Specific examples of the polyfunctional monomer which can be preferably used include diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, and triethylene glycol dimethacrylate. Propylene glycol diacrylate, tripropylene glycol dimethacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, penta Erythritol trimethacrylate, dipe Data hexaacrylate, dipentaerythritol hexa methacrylate, and the like.

The compounding amount of the polyfunctional monomer is 1 to 30 parts by weight per 100 parts by weight of the acrylic polymer. If the amount is less than 1 part by weight, the resulting adhesive will have poor cohesive strength, and if it exceeds 30 parts by weight, the resulting adhesive will have poor adhesive strength.

The radiation-curable hot pressure-sensitive adhesive of the present invention comprises:
It can be prepared by mixing the ingredients.
At this time, additives usually used for the pressure-sensitive adhesive, for example, fillers such as glass fiber and metal powder, pigments, colorants, plasticizers and the like can be added in usual amounts.

The radiation-curable hot pressure-sensitive adhesive of the present invention comprises:
It is cured by irradiation with an active energy ray, for example, an ionizing radiation such as an α-ray, a β-ray, a γ-ray, a neutron beam, an electron beam, or an ultraviolet ray. Irradiation dose is ionizing radiation,
Usually about 0.5 to 20 Mrad, preferably 1 to 10 Mrad. In the case of ultraviolet rays, usually 400 to 3000 mj
/ Cm ² .

The wavelength of the ultraviolet light is preferably in the range of 180 to 460 nm, and the source of the ultraviolet light is preferably a mercury lamp or a metal halide lamp. When curing by irradiation with ultraviolet rays, it is desirable to use a photoreaction initiator (photosensitizer) in combination. Examples of the photoreaction initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, dibenzyl, benzyldimethyl ketal and the like.

[0021] The adhesive tape of the present invention comprises:
Alternatively, it has a layer obtained by curing a coating layer composed of the above-mentioned radiation-curable hot pressure-sensitive adhesive on both surfaces by irradiation with radiation . The hot pressure-sensitive adhesive layer may be fixed to the support or may be detachable from the support. The peelable type can be formed by, for example, a method using a support treated with a release agent. As the support, an appropriate material such as a plastic film, paper, nonwoven fabric, or metal foil may be used. The thickness of the hot pressure-sensitive adhesive layer provided on the support is 1 to
The thickness is generally 500 μm, but is not limited to this and may be an appropriate thickness.

[0022]

The radiation-curable hot pressure-sensitive adhesive of the present invention can be applied with no or little solvent and can be cured by irradiation with radiation. At room temperature before the heat treatment, it shows a weak adhesive force and can be easily re-attached or repositioned, and a strong adhesive force is exhibited by a relatively low temperature of about 100 ° C. or less and a short heat treatment. do it,
Demonstrates excellent adhesive properties with good balance of adhesive strength and holding power.

[0023]

【Example】

Reference Example 1 A reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirrer was charged with 85 parts of 2-ethylhexyl acrylate (parts by weight,
The same applies hereinafter), 10 parts of methyl acrylate, 5 parts of acrylamide, 0.2 parts of 2-hydroxyethyl acrylate,
0.1 part of mercaptoethanol, 2,2'-azobis-
0.2 part of 2-cyanopropanol and 50 parts of toluene were added and polymerized in a nitrogen stream to obtain an acrylic polymer having a weight average molecular weight of 250,000.

Reference Example 2 70 parts of butyl acrylate and isononyl acrylate were placed in a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirrer.
0 parts, 7 parts of vinyl acetate, 3 parts of acrylic acid, 0.3 part of 2,2′-azobisisobutylnitrile, 0.15 part of lauryl mercaptan, and 50 parts of ethyl acetate, and polymerized in a stream of nitrogen to obtain a weight. An acrylic polymer having an average molecular weight of 180,000 was obtained.

Reference Example 3 The acrylic polymer obtained in Reference Example 1 was reacted with 0.6 part of 2-methacryloyloxyethyl isocyanate using 0.1 part of dibutyltin dilaurate to obtain an acrylic polymer having a methacryloyl group. A coalescence was obtained.

Example 1 100 parts of the acrylic polymer obtained in Reference Example 1 and pentaerythritol ester of polymerized rosin (melting point: 120 ° C.) 70
Parts, hydrogenated coumarone indene resin (melting point 100 ° C) 20
Part, and pentaerythritol trimethacrylate 10
The parts were mixed to prepare a radiation-curable hot pressure-sensitive adhesive.
Then, the above-mentioned radiation-curable hot pressure-sensitive adhesive was applied on a separator, dried at 80 ° C. for 3 minutes, and irradiated with an electron beam of 3M.
Irradiation was carried out by rad to obtain an adhesive tape having a cured layer having a thickness of about 50 μm.

Example 2 In place of pentaerythritol ester of polymerized rosin and hydrogenated coumarone indene resin, 50 parts of phenol-modified terpene resin (melting point: 130 ° C.) and 20 parts of styrene resin (melting point: 90 ° C.) were used. In accordance with Example 1, a radiation-curable hot pressure-sensitive adhesive and an adhesive tape were obtained.

Example 3 100 parts of the acrylic polymer obtained in Reference Example 2 and pentaerythritol ester of hydrogenated rosin (melting point 100 ° C.) 80
Part, aromatic modified aliphatic petroleum resin (melting point 90 ° C) 30
Part, and trimethylolpropane trimethacrylate 1
5 parts were mixed to prepare a radiation-curable hot pressure-sensitive adhesive,
Using this, an adhesive tape was obtained according to Example 1.

Example 4 The acrylic polymer obtained in Reference Example 3 was used in place of the acrylic polymer obtained in Reference Example 1, and 5 parts of tetraethylene glycol dimethacrylate was used in place of pentaerythritol trimethacrylate. In accordance with Example 1, a radiation-curable hot pressure-sensitive adhesive and an adhesive tape were obtained.

Comparative Example 1 The amount of pentaerythritol ester of polymerized rosin was 20 parts, and the amount of hydrogenated coumarone indene resin was 10 parts.
Parts, a radiation-curable composition and an adhesive tape were obtained in the same manner as in Example 1.

Comparative Example 2 Instead of pentaerythritol ester of polymerized rosin,
A radiation-curable composition and an adhesive tape were obtained according to Example 1, except that triethylene glycol ester of hydrogenated rosin having a melting point of -18 ° C was used (70 parts).

Evaluation Test The following tests were performed on the adhesive tapes obtained in the examples and comparative examples. Shear adhesive strength An aluminum plate having a thickness of 0.5 mm is interposed between a pressure-sensitive adhesive layer or a composition layer at the time of heating separated from an adhesive tape by 10 mm × 10 mm.
23 ℃, 60 ℃, or 100 ℃
The test piece was crimped under the condition of 1 kg / cm ² for 1 minute, and the shear adhesion of the test piece was measured by an Instron universal tensile tester (tensile speed: 50 mm / min, 23 ° C., 65% RH).

Holding force The test piece (heat-pressed at 100 ° C.) produced in the same manner as described above was left in an atmosphere of 80 ° C. for 20 minutes, and the test piece was dropped, and a 500 g uniform load was applied to its free end. Then, the time until the aluminum plate dropped at 80 ° C. was measured.

The results are shown in Table 1.

[Table 1]

From Table 1, it can be seen that the radiation-curable hot pressure-sensitive adhesive of the present invention has a weak adhesive strength at room temperature before the heat treatment, and a strong adhesive strength at a relatively low temperature for a short time. It shows that the adhesive strength and the holding power are excellent and that they are compatible in a well-balanced manner.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Moroishi 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (56) References JP-A-2-276879 (JP, A) JP-A JP-A-3-220275 (JP, A) JP-A-2-248482 (JP, A) JP-A-62-54777 (JP, A) JP-A-63-43987 (JP, A) JP-A-63-43988 (JP) JP-A-3-35075 (JP, A) JP-A-1-272677 (JP, A) JP-A-3-152178 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) C09J 4/00-4/06 C09J 133/06-133/12 C09J 201/00-201/10 C09J 7/02-7/04

Claims (2)

(57) [Claims] 1. General formula: CH ₂ ＣC (R ¹ ) COOR ²
(However, R ¹ is a hydrogen or methyl group, and R ² is
To 14 alkyl groups. ), 50 to 150 parts by weight of a heat-meltable resin having a melting point of 70 to 200 ° C, and radiation-reactive Contains 1 to 30 parts by weight of a polyfunctional monomer having two or more saturated bonds and is cured by irradiation to show an adhesive strength, and its adhesive strength
Is a solvent-free, radiation-curable, heat-sensitive pressure-sensitive adhesive characterized by exhibiting a property of increasing by heat treatment . 2. A coating layer comprising the radiation-curable hot pressure-sensitive adhesive according to claim 1 on one or both sides of the support.
An adhesive tape having a layer cured by irradiation with radiation .