WO1997030132A1

WO1997030132A1 - Heat-sensitive pressure-sensitive adhesive and heat-sensitive pressure-sensitive adhesive sheet

Info

Publication number: WO1997030132A1
Application number: PCT/JP1996/000341
Authority: WO
Inventors: Kinya Shiraishi; Keiichi Sato; Makoto Kameyama; Hiroyuki Iida; Akira Kikuchi; Masako Yamamoto
Original assignee: Toyo Ink Manufacturing Co., Ltd.
Priority date: 1996-02-16
Filing date: 1996-02-16
Publication date: 1997-08-21

Abstract

A heat-sensitive pressure-sensitive adhesive and a heat-sensitive pressure-sensitive adhesive tape which are excellent in pressure-sensitive adhesiveness and bond strength and resistances to water and moisture. This adhesive comprises (A) 100 pts. by wt. of a thermoplastic resin, (B) 10 to 200 pts. by wt. of a tackifier, (C) 50 to 500 pts. by wt. of a solid plasticizer, (D) an epoxy compound and (E) a thermohardening agent; and the adhesive sheet is produced by applying the adhesive on a support.

Description

Akira Tsumugi book Heat-sensitive adhesive and heat-sensitive adhesive sheet Technical field

The present invention relates to a heat-sensitive adhesive and a heat-sensitive adhesive, which are non-adhesive at room temperature, but exhibit adhesiveness due to heating, and maintain adhesiveness for a while even after the heating source is removed after the adhesiveness is developed. About the sheet. Background art

Conventional heat-sensitive adhesives are often used as water-dispersed adhesives as typified by known delayed tack-type adhesives. For example, as described in “Adhesion Handbook” (1st and 2nd edition, published by The Society of Polymer Publishing, 1980), the basic components are thermoplastic resin, solid plasticizer, and tackifier. Is used in the form of an emulsion or an aqueous dispersion.

Each component plays the following role. In other words, the thermoplastic resin is a source of adhesive force and adhesive force, and the solid plasticizer melts when heated to a temperature higher than its melting point to swell or soften the resin, and the sticking agent expresses adhesiveness. . Further, the tackifier increases the tangling and contributes to the improvement of practical characteristics.

The above-mentioned heat-sensitive adhesive is generally applied on paper such as high-quality paper, coated paper, art paper, vapor-deposited paper, or a plastic substrate such as PET film, and the resulting heat-sensitive adhesive sheet is made of metal. It is used as a label on glass or plastic containers.

Water-dispersed delayed-tack adhesives are excellent in terms of environmental pollution, effects on the human body, resource saving, etc. because they do not contain organic solvents in the system and do not have release paper, but are indispensable because they are water-based There is a disadvantage that the adverse effects of various activators and the like contained inevitably cannot be avoided. In other words, its performance is inferior to solvent-based, such as water resistance and moisture resistance, and its use has been limited.

In recent years, recycling has been carried out in various containers including glass bottles. Labels used on glass bottles that can be used for recycling (recycling) must have water resistance when refrigerated, moisture resistance, and releasability when weakly washed after recovery. It was difficult to satisfy these conditions when using a conventional heat-sensitive adhesive.

The present invention has been made to solve the above-described problems, and has an object to provide a heat-sensitive adhesive which is excellent in water resistance, moisture resistance, tack, and adhesive strength, and can be easily peeled off with a weak alkali. And a heat-sensitive adhesive sheet.

The present invention provides (B) 100 to 200 parts by weight of a tackifier, (C) 50 to 500 parts by weight of a solid plasticizer, and (C) 100 to 100 parts by weight of a thermoplastic resin. D) a compound having an epoxy group; and (E) a heat-sensitive adhesive characterized by containing a thermosetting agent; and a heat-sensitive adhesive formed by coating the heat-sensitive adhesive on a substrate. —Provide BEST MODE FOR CARRYING OUT THE INVENTION

(A) Examples of the thermoplastic resin include (meth) acrylic acid ester, styrene- (meth) acrylic acid ester, styrene-butadiene, ethylene-vinyl acetate, vinyl acetate, vinyl acetate- (meth) acrylic acid ester, ethylene Examples thereof include polymers such as vinyl monochloride, ethylene- (meth) acrylate, ethylene- (meth) acrylic acid, benzene, urethane, and styrene-isoprene.

Also, a copolymer containing a monomer unit constituting these polymers and another monomer unit having copolymerizability can be used. Other monomers include acrylic acid, methacrylic acid, itaconic acid, monomers having a carboxyl group such as (meth) acrylic acid / 3-carboxyethyl, acrylamide, methacrylamide, N —Monomers having an amide group such as methylol acrylamide, monomers having a hydroxyl group such as (meth) hydroxyquinethyl acrylate, monomers having an epoxy group, amino group, etc., and acrylonitrile and vinyltoluene And polymethylstyrene, diarylfurate, and the like.

The thermoplastic resin (A) used in the present invention contains (1) a carboxyl group. A copolymer Ρ ′ having at least a monomer unit, a styrene monomer unit and a (meth) acrylate monomer 及び, and (2) a monomer having no carboxyl group with the copolymer P ′ is preferably at least selected from the group consisting of a mixture of homopolymer [rho ² is one of the resin.

The carboxyl group-containing monomer is preferably at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid and (meth) acrylic acid; 5-carboquinethyl. . Examples of the monomer having no carboxy group include styrene and butyl acetate.

In this way, by introducing the copolymer S P or a mixture of the copolymer P ¹ and the homopolymer P ² , or by using a force, which is particularly suitably used, and the introduction of a carboxyl group, the adhesion to the glass surface is improved. In addition, the formation of a three-dimensional structure by crosslinking with a compound having an epoxy group can be expected, and greatly contributes to the adhesive strength, adhesive strength, water resistance and moisture resistance of the adhesive. In addition, this is because it contributes to the releasability of the label during alkaline washing.

In addition to the presence or absence of a carboxyl group, the monomer composition may affect water resistance in some cases. When importance is placed on water resistance, the use of styrene is particularly preferred. In order to obtain the desired water resistance and alkali releasability, the acid value (amount of hydroxyl group) of the thermoplastic resin is preferably in the range of 5 to 15 OmgKOH / g in the whole resin. More preferably, the acid value is in the range of 5 to 7 OmgKOHZg. If the acid value is less than 5 mgK〇H / g, sufficient water resistance and moisture resistance cannot be obtained, and if it exceeds 15 OmgKOH / g, the stability of the coating solution and the coated sheet will be problematic and impractical. One or more of the monomers having a carboxyl group can be used in combination within the above range. Particularly, itaconic acid and 3-carboxyethyl acrylate are preferably used. The acid value of the resin may be determined by a normal titration method specified in Japanese Industrial Standards, or may be calculated by a potentiometric titration method or by calculation.

Further, the glass transition temperature of the thermoplastic resin is preferably 15 to 50 ° C for the entire resin. More preferably, it is in the range of 0 ° C or more and 40 ° C or less. If the temperature is lower than 15 ° C., blocking tends to occur. On the other hand, if the temperature is higher than 50 ° C., the film-forming property deteriorates, which is not preferable in practical use.

If a homopolymer is used in combination as a thermoplastic resin, each glass transition It is preferable that the approximate value calculated according to the weight ratio from the temperature or the measured value actually obtained by performing a thermal analysis of the mixture is within the above $ 5 range.

As described above, a copolymer Ρ ′ having at least a carboxyl group-containing monomer unit, a styrene monomer unit and a (meth) acrylate monomer unit, and a unit not containing a carboxyl group Monomer ² is obtained by emulsion polymerization in the presence of an ethylenically unsaturated surfactant, that is, a reactive surfactant having a double bond in the molecule. Is preferred. Reactive surfactants are easily incorporated into micelles during polymerization, and are easily copolymerized with coexisting monomers and incorporated into polymer chains. As a result, it is possible to avoid adverse effects on physical properties due to unreacted activator, and to obtain a resin having excellent water resistance and moisture resistance.

Examples of the reactive surfactant include “Latemul S—180” manufactured by Kao Corporation, “Eleminol JS-2” manufactured by Sanyo Chemical Industries, Ltd., and “Αntox MS—600” manufactured by Nippon Emulsifier Co., Ltd. "Daiichi Kogyo Pharmaceutical Co., Ltd." Aqualon HS-10 ",

Powers include, but are not limited to, "AQUALON RN-20", "ADELICA REAL SOAP N E-10" and "ADEKA REAL SOAP S E-10N" manufactured by Asahi Denka Kogyo Co., Ltd. In the emulsion polymerization, one or more of the above-mentioned reactive surfactants can be used in combination. In addition to these reactive surfactants, ordinary anionic, cationic, or nonionic surfactants can be used in combination within a range that does not adversely affect water resistance and moisture resistance.

The amount of the reactive surfactant to be used is preferably 0.05 to 10% by weight, more preferably 0.1 to 5% by weight, based on 100 parts by weight of the monomer mixture.

(B) The adhesion-imparting agent is used in the range of 100 to 200 parts by weight based on 100 parts by weight of the thermoplastic resin (A) for the purpose of improving the adhesive performance of the adhesive. When the amount is less than 100 parts by weight, the adhesive strength and the adhesive force are reduced. On the other hand, when the amount is more than 200 parts by weight, blocking easily occurs. Examples of the tackifier include polymerized rosin, hydrogenated rosin, glycerin esters thereof, rosin derivatives such as pentaerythritol ester, polyterpene resins such as phenol-modified terpene resins, and aliphatic hydrocarbon resins (C5 petroleum resin). And aromatic hydrocarbon resins (C9 resin) such as chromanindene resin and their hydrogenated products, and other alkylphenols Conventionally known resins such as resins and alkylated polystyrene resins are exemplified. However, those having a softening temperature of 80 ° C. or more are preferable in consideration of the π-booking property.

The (C) solid plasticizer is used in an amount of 50 to 500 parts by weight, preferably 70 to 400 parts by weight, per 100 parts by weight of the thermoplastic resin (A). Used in. If it is used in an amount less than 50 parts by weight, the plasticizing effect is reduced and sufficient adhesive strength and adhesive strength cannot be obtained. Also 5 0

When used in excess of 0 parts by weight, chalking (powder phenomenon of the solid plasticizer) is likely to occur. Examples of solid plasticizers include diphenyl fluorate, dihexyl fluorate, dicyclohexyl fluorate, dihydroabiethyl phthalate, dimethyl isophthalate, dimethyl terephthalate, and terephthalate. Dibenzyl diluate, p — Methyl hydroxyquine benzoate, p — N-propyl hydroxybenzoate, Sucrose benzoate, Ethylene glycol dibenzoate, Trimethylolethane tribenzoate, Glyceride tribenzoate, Tetrabenzoic acid Examples include pentaerythritol, sucrose octaacetate, monomethyl itaconate, dimethyl itaconate, N-cyclohexyl-p-toluenesulfonic acid amide, tricycl π-hexyl citrate, and triphenyl phosphate. One or more of these solid plasticizers can be used in combination, but it is preferable to use dicyclohexyl phthalate, which is highly versatile.

(D) The compound having an epoxy group is important for significantly improving various properties such as adhesive strength, adhesive strength, water resistance and moisture resistance of the pressure-sensitive adhesive. It can be used irrespective of solid or liquid (liquid). However, when liquid at room temperature (25 ° C), (A) 100 to 100 parts by weight of thermoplastic resin A range of 50 parts by weight is preferred. If it is used in excess of 50 parts by weight, problems such as a decrease in the stability of the coating liquid occur. On the other hand, in the case of a solid at room temperature, the range is preferably 20 to 200 parts by weight. If the amount is less than 20 parts by weight, the effect of improving the physical properties cannot be obtained. If the amount is more than 200 parts by weight, the plasticizing effect at the time of thermal activation becomes difficult to obtain, and the workability and the like deteriorate.

Compounds having an epoxy group that are liquid or liquid at room temperature include glycidyl ethers such as arylglycidyl ether and phenylglycidyl ether, alkylene oxides such as styrene oxide and propylene oxide, and glycidyl phthalate. Glycidyl esters such as esters, glycidylamines such as N, N-diglycidylaniline, tetraglycidyldiaminodiphenylmethane, etc. Dalicidyl acrylate, glycidyl methacrylate and the like can be mentioned.

Triglycidyl isocyanurate, hydantoin type epoxy resin, hydroquinone glycidyl ether, bisphenol s type epoxy resin, glycidyl sulfate Mid, biphenyl type epoxy resin, cresol nopolak type epoxy resin, (hydrogenated) bisphenol A type epoxy resin, (hydrogenated) bisphenol F type epoxy resin, brominated bisphenol A type epoxy resin, phenol Novolak type epoxy resins and the like can be mentioned.

These epoxy compounds may be used alone or in combination of two or more in the above-mentioned range irrespective of liquid or solid. Among them, glycidyl ethers such as glycerol triglycidyl ether, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, trimethylolpronitol glycidyl ether, and neopentyl glycol diglycidyl ether Preferred are bisphenol A type epoxy resin, triglycidyl isocyanurate, cresol novolak type epoxy resin, and phenol novolak type epoxy resin.

(E) The thermosetting agent is important for the purpose of improving the physical properties of the pressure-sensitive adhesive. As the heat hardening agent, those known in the art, for example, those described on pages 606 to 655 of "Handbook of Crosslinking Agents" (Showa 56, Taiseisha), "New Epoxy Resin" (Showa 6 (0, Shokodo) Pages 164 to 263 can be used, but the present invention is not limited thereto. Of these, amines, particularly those having hydrophilicity such as 2-dimethylaminoethanol, are preferred because of their excellent workability. These can be used irrespective of whether they are solid or liquid, but the amount is preferably 1 to 50 parts by weight based on 100 parts by weight of (A) the thermoplastic resin.

The thermosetting agent can be used alone or in combination of two or more, and a thermosetting accelerator can also be used. Examples include acetylacetone metal salts such as zinc acetyl acetate and iron acetyl acetate, enamin, tin octoate, quaternary phosphonium salts, triphenyl phosphine, 1,8-diene Rinbincro— (5,4,0) -ndecene 7 and its 2-ethylhexanoic acid And phenol salts, triammonol borate and the like.

In addition to the components (A) to (E) described above, the heat-sensitive adhesive of the present invention may further comprise (F) other components as necessary for the purpose of improving physical properties, workability, workability, and the like. Additives can be used.

Other additives include, for example, inorganic fillers such as titanium oxide, alumina, alumina sol, kaolin, colloidal silica, talc, my force, paraffin, wax, and the like for the purpose of preventing blocking or controlling adhesive strength. Organic substances such as oils and fats are exemplified. Also, various dispersants, defoamers, thickeners and the like can be used. The heat-sensitive adhesive of the present invention comprises the above-mentioned (C) solid plasticizer, and if necessary, (D) solid epoxy resin, and (F) other additives, first of all, such as a ball mill, an attritor, a sand mill, etc. After pulverizing and dispersing with water etc. using means for dispersing and kneading, (A) a thermoplastic resin, (B) a tackifier, (D) an epoxy resin, and if necessary, (F) other additives Can be obtained by adding, mixing and stirring. The resulting heat-sensitive adhesive is applied on a substrate by a usual method such as hot melt coating, overnight coating, bar coating, application coating, brush coating, or the like, and if necessary, heating. Air-drying, far-infrared drying, etc. can be performed to obtain a heat-sensitive adhesive sheet. Example

Next, the present invention will be described specifically with reference to examples, but these do not limit the present invention at all. In the examples, “parts” represents “parts by weight”, and [%] represents “% by weight”.

[Examples 1 to 10 and Comparative Examples 1 to 7]

According to the formulation shown in Table 2, (C) a solid plasticizer, (F) a maleic resin solution and water were first placed in a ball mill and ground and dispersed for 24 hours. Next, (A) a thermoplastic resin, (B) a tackifier, (D) an epoxy compound and (E) a thermosetting agent were added, and the adhesive was adjusted by mixing and stirring with a disper for 5 minutes. _The acrylic resin emulsion was prepared according to the composition shown in Table 1 in a nitrogen atmosphere 7 (normal emulsion polymerization was performed at TC to obtain emulsions with 50% solids, respectively _). In the table, "Emal 10" is sodium lauryl sulfate manufactured by Kao Corporation, and "HS-10" is a reactive surfactant manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.

The obtained pressure-sensitive adhesive was applied to the back side of a single-sided art paper so that the coated amount after drying was 15 g Zm ^2, and dried at 45 ° C. for 30 seconds to obtain a pressure-sensitive adhesive sheet. After drying, no stickiness of the sheet at room temperature was observed. The obtained sheets were evaluated for 180 ° peel adhesion, holding power, water resistance, alkali cleaning properties and blocking properties by the following methods. The results are shown in Table 2.

table 1

(Adhesive strength)

After heating the glue sheet at 120 ° C for 25 seconds to develop adhesiveness, it is immediately pasted on a stainless steel plate and a glass plate and separated at 180 ° according to JISK-6848. Was used to measure the adhesive strength. The measurement results were determined based on the following criteria.

◎ 100 0 g / 25 mm or more

〇 700 g / 25 mm or more 100 g g <25 mm

Δ 400 g / 25 mm or more 700 g g less than 25 mm

x 400 g / less than 25 mm

(Holding force)

After developing the adhesiveness in the same manner as in the case of the adhesive strength, the adhesive sheet was immediately attached to a stainless steel plate and a glass plate, and a creep test was performed in accordance with JIS K-6848, and evaluated according to the following criteria.

◎ Over 500 seconds

〇 3 0 0 0 seconds or more and less than 5 0 0 0 seconds

△ 1 0 0 0 seconds or more and less than 3 0 0 0 seconds

X less than 100 seconds

(water resistant)

A 25 x 100 mm adhesive sheet that developed adhesiveness as in the case of adhesive strength was quickly attached to a glass plate.After leaving it for 24 hours, it was placed in a water bath at 25 ° C. Soaked. 48 hours later, the attached state of the attached sheet was observed and evaluated according to the following criteria.

◎ Less than 10% of the adhered adhesive sheet area peeled off.

1 10% or more and less than 30% of the adhesive sheet area separated.

△ 30% or more and less than 60% of the adhesive sheet area separated.

X More than 60% of the adhesive sheet area peeled off.

(Cleanability)

A 250-mm-thick adhesive sheet that developed adhesiveness as in the case of adhesive strength was quickly attached to a glass plate, left for 24 hours, and then left at 70 ° C 3% sodium hydroxide aqueous solution. The sample was immersed in water and the separation time was measured, and evaluated according to the following criteria.

◎ Separated within 5 minutes. 剝 Separated in 5 minutes or more and less than 10 minutes.

The separation occurred in Δ10 minutes or more and less than 20 minutes.

It took more than 20 minutes.

(Procking property)

A load was applied to the adhesive sheet so as to be 500 g Z cm ^2, and the degree of sticking when left for 1 hour in an atmosphere of 55 was evaluated according to the following criteria.

5 なし No separation resistance

4 Slight noise when peeling

3 連 Rust sound at separation

2 紙 Paper breaks when separated

1 Not detachable Supplementary explanation of Table 2 below

* 1) Styrene benzene copolymer, solid content 50%

* 2) Ethylene vinyl acetate copolymer, solid content 50%

* 3) See Table 1, 50% solids each

* 4) Solid content 50%

* 5) Solid content 30% Industrial applicability

The heat-sensitive adhesive and the heat-sensitive adhesive sheet of the present invention improve water resistance and moisture resistance, which were difficult with conventional water-dispersed pressure-sensitive adhesives, and are excellent in adhesive strength and adhesive strength. It is used for a wide range of applications where the above characteristics are required, such as labels used for various containers such as glass bottles for collection and use.

Claims

Claims: (A) 100 parts by weight of thermoplastic resin, (B) 100 to 2 parts by weight of tackifier, (C) 50 to 500 parts by weight of solid plasticizer, (D) a compound having an epoxy group; and (E) a heat-sensitive adhesive containing a thermosetting agent.

2. (D) The compound having an epoxy group is liquid at room temperature, and (A) 100 parts by weight of the thermoplastic resin,! The heat-sensitive adhesive according to claim 1, which is contained in an amount of from 50 to 50 parts by weight.

3. The heat sensitivity according to claim 1, wherein (D) the compound having an epoxy group is solid at room temperature, and (A) the thermoplastic resin is contained in an amount of 20 to 200 parts by weight based on 100 parts by weight of the thermoplastic resin. Adhesive.

4. The heat-sensitive adhesive according to claim 2, wherein (D) the compound having an epoxy group is at least one compound of glycidyl ethers.

5. The heat-sensitive adhesive according to claim 3, wherein (D) the compound having an epoxy group is at least one resin selected from the group consisting of a bisphenol epoxy resin and a cresol novolac epoxy resin.

6. The heat-sensitive adhesive according to claim 1, wherein the (E) thermosetting agent is an amine.

7. The heat-sensitive adhesive according to claim 4, wherein the (E) thermosetting agent is an amine.

8. The heat-sensitive adhesive according to claim 5, wherein (E) the thermosetting agent is an amide.

9. (A) The thermoplastic resin is a copolymer P ′ having at least (1) a carboxyl group-containing monomer unit, a styrene monomer unit and a (meth) acrylate monomer unit. (2) at least selected from the group consisting of a mixture of the copolymer P 'and the homopolymer P ² of the monomer containing no carboxyl group is one resin The heat-sensitive adhesive according to claim 1.

10. The monomer containing a carboxyl group is at least 1% of a monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid and S-carboxyethyl (meth) acrylate. 9 heat-sensitive adhesives.

1 1. A copolymer in which the thermoplastic resin (A) has at least (1) a monomer unit containing a carboxyl group, a styrene monomer unit, and a (meth) acrylate monomer unit. P 'and (2) the copolymer P' and homopolymer P ² a mixture thermosensitive claim 4 Ru least one resin der selected from the group consisting of monomers containing no carboxyl group Adhesive.

1 2. A copolymer in which (A) the thermoplastic resin has at least (1) a monomer unit having a carboxyl group, a styrene monomer unit and a (meth) acrylate monomer unit. P 'and (2) the copolymer P' and heat-sensitive mixture Ru least one resin der selected from the group consisting of compounds according to claim 5 of the homopolymer P ² of the monomer containing no carboxyl group Adhesive.

1 3. copolymer P 'and homopolymers P ² are as claimed in claim 9, which is a polymer obtained by emulsion polymerization in the presence of a surfactant having an ethylenically unsaturated bond monomer constituent units Heat-sensitive adhesive.

14. The heat-sensitive adhesive according to claim 13, wherein (A) the thermoplastic resin has an acid value of 5 mgK〇HZg to 150 mgKOHZg in the entire resin.

15 (A) The heat-sensitive adhesive according to claim 14, wherein the glass transition temperature of the thermoplastic resin is from 15 ° C to 5 (TC) as a whole of the resin.

1 6. A heat-sensitive adhesive sheet obtained by coating the heat-sensitive adhesive of claim 1 on a substrate.

] 3

1 7. A heat-sensitive adhesive sheet obtained by coating the heat-sensitive adhesive of claim 11 on a substrate.

1 8. A heat-sensitive adhesive sheet obtained by coating the heat-sensitive adhesive of claim 12 on a substrate.