JPH05117611A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide an adhesive composition which is superb in operating efficiency and excellent in thermal creep resistance, water resistance, heat resistance, low-temperature adhesion, cold resistance and mechanical strength in spite of being of one-pack type. CONSTITUTION:The composition comprises 20-80wt.% ethylene-vinyl chloride resin emulsion, 10-80wt.% acrylic resin emulsion, which is prepared by emulsion- polymerizing an acrylic monomer in the presence of an acrylic copolymer as a protective colloid and has a glass transition temperature of -20 deg.C to +20 deg.C, and 5-50wt.% urethane resin emulsion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to adhesive compositions.
More specifically, it relates to an adhesive composition having excellent heat resistance and creep resistance even though it is a one-component type, and having excellent water resistance, heat resistance, low-temperature adhesion and mechanical stability.

[0002]

2. Description of the Related Art Conventionally, an ethylene-vinyl acetate copolymer emulsion has been widely used as an adhesive for overlaying a vinyl chloride resin sheet.
Vinyl acetate copolymer emulsions generally have the drawback that their adhesiveness changes significantly with temperature. Therefore, when the ethylene-vinyl acetate copolymer emulsion is used, a solvent at a low temperature and a resin having a high hardness at a high temperature are blended in order to improve the adhesiveness, but the concentration is 5% or more. When the organic solvent is mixed, there is a problem that local exhaust equipment is required by the Industrial Safety and Health Act, and when a resin with high hardness is mixed, the adhesiveness at low temperature becomes poor. Since there is a problem of insufficient adhesiveness, development of an adhesive having excellent adhesiveness over a wide temperature range has been awaited.

As an adhesive composition having relatively excellent adhesiveness in a wide temperature range, an adhesive composition comprising a polyester type water-soluble or water-dispersible urethane resin, an aziridine ring compound and an aqueous latex is known. (Japanese Patent Publication No. 63-33518), such an adhesive composition is a two-part type of urethane resin and an aqueous latex and an aziridine ring compound, and the crosslinking reaction can proceed at room temperature at the same time when the two are mixed. It has shortcomings that the usage time is short, a complicated procedure is required for mixing the two, the mixture cannot be stored, and the workability during continuous use is poor.

[0004]

Therefore, the present inventors have found that
As a result of intensive studies to improve the adhesiveness and heat resistance of the adhesive composition in a wide temperature range and to develop a one-component adhesive composition having excellent workability, all of the above physical properties are satisfied. The present invention finally completed the present invention and completed the present invention.

[0005]

[Means for Solving the Problems] That is, the present invention is (A)
20-80% by weight of ethylene-vinyl acetate resin emulsion,
(B) 10-80% by weight of an acrylic resin emulsion having a glass transition point of -20 to + 20 ° C obtained by emulsion polymerization of an acrylic monomer in the presence of an aqueous solution or emulsion of an acrylic copolymer as a protective colloid and ( C) An adhesive composition comprising 5 to 50% by weight of a urethane resin emulsion.

[0006]

[Operation and Examples] As described above, the adhesive composition of the present invention comprises (A) an ethylene-vinyl acetate resin emulsion.
20 to 80% by weight, (B) a glass transition point of -20 to +20 obtained by emulsion polymerization of an acrylic monomer in the presence of an aqueous solution or emulsion of an acrylic copolymer as a protective colloid.
℃ acrylic resin emulsion 10-80% by weight and
(C) Consists of 5 to 50% by weight of urethane resin emulsion.

The ethylene-vinyl acetate resin emulsion (A) is used as a main component of the adhesive composition of the present invention.

If the ethylene content of the ethylene-vinyl acetate resin contained in the above-mentioned (A) ethylene-vinyl acetate resin emulsion is too high, the resin becomes soft and the heat resistance becomes poor, and if it is too low. In the meantime, the resin tends to be hard and the cold resistance tends to be poor, so that it is preferably 5 to 40% by weight, and particularly 15 to 30% by weight. The weight average molecular weight of the ethylene-vinyl acetate resin is not particularly limited, but its production becomes difficult as the weight average molecular weight increases, and the plasticity due to heat increases as the weight average molecular weight decreases. Deformation is likely to occur and heat resistance tends to be poor, so it is 50000 to 1000000, especially 2000.
It is preferably 00 to 800,000.

Further, in the (A) ethylene-vinyl acetate resin emulsion, the ethylene-vinyl acetate resin is 40 to
It is preferably contained in the range of 65% by weight, especially 55 to 60% by weight. If the content of the ethylene-vinyl acetate resin is smaller than the above range, the moisture content becomes relatively large, and the drying time of the adhesive composition becomes long, and if it is larger than the above range. However, it tends to be difficult to produce a resin emulsion.

The blending amount of the above-mentioned (A) ethylene-vinyl acetate resin emulsion is adjusted so that the resulting adhesive composition contains 20 to 80% by weight, particularly 40 to 70% by weight. When the amount is less than the above range, the adhesion to the wood-based adherend becomes small, and when the amount is more than the above range, the adhesion and heat resistance to the vinyl chloride resin sheet are small. Creep tends to be poor.

One of the major features of the present invention is that the (B) acrylic resin emulsion is used. When such an acrylic resin emulsion is used, a wide temperature range of the obtained adhesive composition can be obtained. In the range, especially the adhesiveness to a vinyl chloride resin sheet is remarkably improved as compared with a conventional adhesive composed of an ethylene-vinyl acetate resin emulsion.

The protective colloid of the acrylic copolymer used in the (B) acrylic resin emulsion means that the acrylic copolymer can be emulsion copolymerized with the acrylic copolymer dissolved or dispersed in water. It has the ability.

The acrylic copolymer is an unsaturated carboxylic acid such as (meth) acrylic acid, and methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic. Acid methoxyethyl, (meth) acrylic acid diethylene glycol, (meth) acrylonitrile, a copolymer with a (meth) acrylic acid ester such as (meth) acrylamide, the aqueous solution or emulsion of the acrylic copolymer, A water-soluble or water-dispersible polymer obtained by neutralizing an acrylic copolymer with an alkali such as ammonia or an organic amine. When the (meth) acrylic acid content in the acrylic copolymer is too small, the solubility in an alkaline aqueous solution becomes poor, the effect as a protective colloid becomes insufficient, and when it is too large, Has a property as a protective colloid, but its adhesiveness to the vinyl chloride resin sheet tends to be poor, so that it is preferably 2 to 50% by weight, particularly 5 to 20% by weight.

When the weight average molecular weight of the acrylic copolymer is too large, the effect as a protective colloid becomes too small, and when it is too small, an emulsifier is used. As with the case, heat resistance tends to be poor, so 1000-200000,
Preferably 2000 to 150,000, more preferably 10000 to 10
It is preferably about 0000.

The protective colloid of the acrylic copolymer is obtained by mixing a monomer such as acrylic acid or (meth) acrylic acid ester with a polymerization initiator such as azobisisobutyronitrile and a solvent such as isopropyl alcohol. Stirring while heating to about 70-80 ° C, removing the solvent after the reaction, and adding a neutralizing agent such as water and ammonia water so that the concentration of the acrylic copolymer is about 10-40% by weight. It can be obtained by doing.

The acrylic resin emulsion (B) can be obtained by emulsion-polymerizing an acrylic monomer in the presence of a protective colloid of the acrylic copolymer.

Examples of the acrylic monomer include (meth) acrylic acid, methyl (meth) acrylate,
Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate 2-
Ethylhexyl, methoxyethyl (meth) acrylate,
Examples thereof include methoxyethyl (meth) acrylate and ethoxydiethylene glycol (meth) acrylate, which may be used alone or in admixture of two or more.

In the present invention, the above acrylics such as acrylonitrile, methacrylonitrile, styrene, acrylamide, methacrylamide, vinyl acetate, itaconic acid, maleic acid, crotonic acid, etc. are used within the range that the object of the present invention is not hindered. A monomer copolymerizable with the system monomer may be blended.

By mixing the protective colloid containing the acrylic copolymer with the acrylic monomer and copolymerizing the acrylic monomer, the acrylic resin emulsion (B) can be obtained. The blending ratio of the acrylic copolymer and the acrylic monomer is such that the acrylic copolymer contained in the protective colloid is usually 5 parts by weight with respect to 100 parts by weight of the acrylic monomer (parts by weight, hereinafter the same).
It is desirable to adjust to 20 parts, preferably 10 to 15 parts. When the proportion of the acrylic copolymer is less than the above range, it becomes difficult to prepare a resin emulsion, and when it is more than the above range, the adhesion to the vinyl chloride resin sheet becomes poor. Tend.

When the acrylic monomer is copolymerized in the protective colloid containing the acrylic copolymer, the acrylic monomer is gradually added, and a polymerization initiator such as ammonium persulfate is added. However, it is preferable to heat to about 60 to 80 ° C. with stirring.

Thus, the (B) acrylic resin emulsion is obtained, and the glass transition point of the acrylic resin which is an emulsion polymer of the acrylic monomer contained in the acrylic resin emulsion has a glass transition point of -20 to + 20 ° C. , Select and adjust the type of acrylic monomer so that the temperature will be -10 to + 10 ° C. If the glass transition point is lower than the above range, the heat resistance of the obtained adhesive composition will be decreased, and if it is higher than the above range, the adhesive composition obtained will be bonded. It tends to be inferior in sex.

The amount of the resin component contained in the acrylic resin emulsion (B) is determined by the amount of water and the amount of acrylic monomer to be blended when the protective colloid is prepared, as described above.

The blending amount of the acrylic resin emulsion (B) is adjusted so that the resulting adhesive composition contains 10 to 80% by weight, particularly 50 to 70% by weight. When the amount is less than the above range, the adhesiveness of the obtained adhesive composition to the vinyl chloride resin sheet becomes insufficient, and when the amount is more than the above range, the adhesive obtained. The composition tends to have poor mechanical suitability such as poor coatability.

The urethane resin emulsion (C) is a component for imparting heat resistance and improving adhesion to the vinyl chloride resin sheet.

The urethane resin contained in the urethane resin emulsion (C) has, for example, a softening point of 40 to 120.
A temperature of about ℃ is used.

If the content of the urethane resin is too large, the adhesive force to the wood-based adherend becomes small, and if it is too small, the heat resistance tends to be poor. 5-60% by weight, especially 20-
It is preferably about 50% by weight.

As a typical example of the urethane resin emulsion (C), for example, Desmocol VPKA-8, which is an aliphatic isocyanate polyester urethane emulsion.
481 (Sumitomo Bayer Urethane Co., Ltd., trade name, softening point 7
UXA-3005 (Sanyo Kasei Co., Ltd.), which is an aromatic isocyanate polyester urethane emulsion
Manufacturer, trade name, softening point 50 ° C), etc.

The compounding amount of the urethane resin emulsion (C) is adjusted so that the obtained adhesive composition contains 5 to 50% by weight, particularly 20 to 40% by weight. When the amount is less than the above range, the heat resistance tends to be poor, and when the amount is more than the above range, the adhesive force to the wood-based adherend tends to be low.

By mixing (A) the ethylene-vinyl acetate resin emulsion, (B) the acrylic resin emulsion and (C) the urethane resin emulsion, the adhesive composition of the present invention can be obtained. In order to improve the temperature, a solvent, a plasticizer or the like may be appropriately added.

Specific examples of the solvent include aromatic solvents such as toluene and xylene; ether solvents such as ethylene glycol diethyl ether and diethylene glycol diethyl ether; ketone solvents such as cyclohexanone and isophorone; butyl acetate and diacetic acid. Examples include ester solvents such as ethylene glycol.

Specific examples of the plasticizer include dibutyl phthalate and dimethyl succinate.

In the adhesive composition of the present invention, if necessary, for example, fillers such as silicate fine powder, calcium carbonate, wheat flour and corn starch; water repellents such as sodium dialkylsulfosuccinate; Thickeners such as methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose may be added.

As described above, the adhesive composition of the present invention comprises (A) an ethylene-vinyl acetate resin emulsion and (B)
Consists of acrylic resin emulsion and (C) urethane resin emulsion, and by including the (B) acrylic resin emulsion, it has excellent adhesion to, for example, a vinyl chloride resin sheet and is excellent in a wide temperature range. It exhibits adhesiveness.

Therefore, the adhesive composition of the present invention can be preferably used as an adhesive for overlaying a vinyl chloride resin sheet, for example.

Next, the adhesive composition of the present invention will be described in more detail based on Production Examples and Examples, but the present invention is not limited to these Examples.

Production Example 1 In a 500 ml four-necked flask equipped with a thermometer, a stir bar and a reflux device, 16 g of ethyl acrylate and 4 acrylic acid were added.
g, 80 g of isopropyl alcohol, and 0.2 g of azobisisobutyronitrile were added, and the mixture was stirred for 4 hours while adjusting the internal temperature to 80 ° C. with a water bath.

Next, the internal temperature was adjusted to 90 ° C., isopropyl alcohol was removed under reduced pressure, and then ion-exchanged water was added.
86.2 g and 3.8 g of 25% aqueous ammonia were added to obtain a protective colloid of acrylic copolymer.

Next, the temperature of the protective colloid in the flask was adjusted to
Adjust the temperature to 75 ℃ and stir with ammonium persulfate 0.1 g
After adding, butyl acrylate 30g, acrylic acid 2-
A mixture of 30 g of ethylhexyl, 20 g of styrene and 20 g of acrylonitrile was added dropwise over 2 hours, the reaction was continued at 75 ° C. for 2 hours, and then 10 g of xylene was added.
The mixture was stirred for 1 minute and then allowed to cool to room temperature to obtain an acrylic resin emulsion.

The glass transition point of the resin component contained in the obtained acrylic resin emulsion was measured with a differential scanning calorimeter (DSC-20, manufactured by Seiko Denshi Kogyo Co., Ltd.) and found to be -12 ° C. ..

Production Example 2 and Comparative Production Examples 1-2 In Production Example 1, 30 g of butyl acrylate and acrylic acid
An acrylic resin emulsion was obtained in the same manner as in Production Example 1 except that the mixture shown in Table 1 was used instead of the mixture of 30 g of 2-ethylhexyl, 20 g of styrene and 20 g of acrylonitrile.

The glass transition point of the resin component contained in the obtained acrylic resin emulsion was examined in the same manner as in Production Example 1. The results are shown in Table 1.

[0042]

[Table 1]

Comparative Production Example 3 In a 500 ml four-necked flask equipped with a thermometer, a stir bar and a reflux device, 5 g of polyethylene alkyl phenyl ether (manufactured by Kao Corporation, Emulgen) and sodium lauryl sulfate (manufactured by Kao Corporation). , Emal O) 5g and deionized water 90g are put, and the internal temperature is 75 ℃ in a water bath.
Ammonium persulfate (0.1 g) was added while controlling so that butyl acrylate (20 g), 2-ethylhexyl acrylate (20 g), styrene (30 g) and acrylonitrile (30 g) were added dropwise over 2 hours.

After the completion of dropping, the contents were aged at 75 ° C. for 2 hours, 10 g of xylene was added, and the mixture was stirred for 30 minutes and allowed to cool to room temperature to obtain an acrylic resin emulsion.

When the glass transition point of the resin component contained in the obtained acrylic resin emulsion was examined in the same manner as in Production Example 1, it was + 10 ° C.

Examples 1 to 5 and Comparative Examples 1 to 5 Sumikaflex # 401 (trade name, manufactured by Sumitomo Chemical Co., Ltd., ethylene content 30% by weight, resin content 55% by weight) as an ethylene-vinyl acetate resin emulsion, urethane Desmocol VPKA-8481 (Sumitomo Bayer Urethane Co., Ltd., trade name) was used as the resin emulsion, and those obtained in Production Examples 1-2 and Comparative Production Examples 1-3 were used as the acrylic resin emulsion. The adhesive composition was obtained by mixing at the compounding ratio shown in 2.

The physical properties of the obtained adhesive composition were examined for normal peel strength, water peel resistance, heat creep resistance, cold resistance, low temperature adhesion and local load strength according to the following methods. The results are shown in Table 2.

(A) Normal peel strength Using a JAS I type plywood as a substrate, an adhesive composition was applied onto the plywood by a roll coating method so that the thickness of the coating film was 0.1 mm, and then hard chloride was applied. Vinyl resin sheets (plasticizer content: 10% by weight, thickness: 0.2 mm) were stacked to obtain a laminate.

Next, the obtained laminated body is pressured at 0.5 kg / cm ²
After compressing for 24 hours, decompress and cure at 20 ° C for 3 days,
Then, it was cured at 50 ° C. for 1 day to prepare a test body.

The width of the test piece was adjusted to 2.5 cm, and the room temperature was 25 ° C.
The peel strength was measured when the hard vinyl chloride resin sheet was peeled off at an angle of 180 ° at a tensile speed of 120 mm / min in a constant temperature and humidity chamber with a humidity of 60% and a Shopper type tensile strength tester. The evaluation criteria are as follows.

(Evaluation Criteria) ○: Peel strength of 1.5 kg / cm or more ×: Peel strength of less than 1.5 kg / cm (b) Water resistant peel strength The width of the test body obtained by the above (a) Normal peel strength is 2.5. cm
After being immersed in water at room temperature for 24 hours, the peel strength was measured in a constant temperature and humidity chamber in the wet state in the same manner as in (a) above. The evaluation criteria are as follows.

(Evaluation Criteria) ◯: Peel strength of 0.5 kg / cm or more X: Peel strength of less than 0.5 kg / cm (c) Heat-resistant creep resistance The width of the test body obtained by the above (a) Normal peel strength is 2.5. cm
After peeling off one end of the hard vinyl chloride resin sheet and attaching a load of 500 g to that end, lift the test body so that it is horizontal, and apply the load in the vertical direction for 24 hours. It was left to stand in a hot air circulation dryer (60 ° C). After that, the test body was taken out from the dryer and evaluated based on the following evaluation criteria.

(Evaluation Criteria) ◯: Peeling length is less than 5 mm ×: Peeling length is 5 mm or more (d) Cold resistance The specimen obtained in (a) Normal peel strength is kept in a constant temperature chamber at -20 ° C. After being left inside for 24 hours, the state of the test piece when one end of the hard vinyl chloride resin sheet was momentarily peeled from the plywood was visually observed. The evaluation criteria are as follows.

(Evaluation Criteria) ◯: Rupture occurred in the hard vinyl chloride resin sheet X: No abnormality was observed in the hard vinyl chloride resin sheet and plywood, and both were peeled off (e) Low temperature adhesiveness Particles cooled in advance to 5 ° C. After the adhesive composition was applied on the board to a thickness of 0.1 mm, the same rigid vinyl chloride resin sheet as used in (a) above was applied and cured again in a thermostatic chamber at 5 ° C for 5 days. After that, the state of the test piece when one end of the hard vinyl chloride resin sheet was momentarily peeled off from the plywood was visually observed.

(Evaluation Criteria) ◯: Rupture occurred in the hard vinyl chloride resin sheet ×: No abnormality was found in the hard vinyl chloride resin sheet and plywood, and both were peeled off (f) Local load strength (a) Normal peel strength Insert the obtained test piece between two acrylic plates and tighten it with bolts and nuts so that a load of 10 kg / cm ² will be applied.
The test was repeated with one cycle in which the sample was left in an atmosphere of 0 ° C. for 3 hours and then left in an atmosphere of + 60 ° C. for 2 hours, and evaluated based on the following evaluation criteria.

(Evaluation Criteria) ◯: No abnormalities such as blistering occur on the hard vinyl chloride resin film even after 5 cycles. Δ: Abnormalities such as blister are observed on the hard vinyl chloride resin film in 3 to 4 cycles. X: Abnormalities such as blister are observed on the hard vinyl chloride resin film after 2 cycles or less.

[0057]

[Table 2]

From the results shown in Table 2, the adhesive compositions obtained in Examples 1 to 5 were excellent in heat resistance creep resistance, water resistance, heat resistance, low temperature adhesion, cold resistance and mechanical strength. It can be seen that it is.

[0059]

INDUSTRIAL APPLICABILITY The adhesive composition of the present invention is excellent in heat creep resistance, water resistance, heat resistance, low temperature adhesiveness, cold resistance and mechanical strength at the same time, although it is a one-component type. Therefore, it can be suitably used in a wide temperature range, for example, as an adhesive for overlay of vinyl chloride resin sheets.

Claims (1)

[Claims] 1. A glass transition obtained by emulsion-polymerizing an acrylic monomer in the presence of (A) an ethylene-vinyl acetate resin emulsion in an amount of 20 to 80% by weight, (B) an aqueous solution or emulsion of an acrylic copolymer as a protective colloid. Point is -20 ~
An adhesive composition comprising 10 to 80% by weight of an acrylic resin emulsion at + 20 ° C. and 5 to 50% by weight of (C) a urethane resin emulsion.