JP2000129239A - Moisture-curable adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-pack type moisture-curable urethane adhesive composition which finally exhibits excellent adhesion strength even if curing of the adhesive composition which had been coated on the portion difficult to come into contact with air (moisture) is retarded and, simultaneously, does not cause defects in the coated portions such as a failure in external appearance by uniformly and stably dispersing foams by a carbon dioxide gas to be generated at the time of moisture-curing into an adhesive layer. SOLUTION: This moisture-curable adhesive composition comprises 100 pts.wt. urethane prepolymer having isocyanate groups at both terminals to be obtained by reacting the terminal hydroxyl groups of a polyol with a polyfunctional isocyanate compound and 0.01-50 pts.wt. foam stabilizer. The foam stabilizer is a silicone type foam stabilizer and the polyol is a polyester polyol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a one-part, moisture-curable urethane-based adhesive composition.

[0002]

2. Description of the Related Art A one-pack type moisture-curable urethane-based adhesive composition is a one-pack type and has good workability and exhibits an excellent balance of performance after curing. In place of rubber-based solvent-based adhesives and two-component mixed-type epoxy-based adhesives that have been used, in particular, floor-site, wall-panel, and ceiling-site construction adhesives, industrial adhesives, general-purpose adhesives,
The demand for sealing agents and the like is expanding.

However, the moisture-curable urethane-based adhesive composition generates carbon dioxide gas when it reacts with moisture in the air or moisture in an adherend to generate carbon dioxide, and foaming occurs. There is a problem that it tends to be insufficient. This phenomenon is particularly remarkable in a case where it is difficult to sufficiently control the humidity in the air, the moisture content in the adherend, and the like, for example, in an on-site construction application such as a building or civil engineering.

Further, since the moisture-curable urethane-based adhesive composition is of a type in which the curing proceeds due to the reaction with moisture, the portion which comes into contact with air (moisture) cures satisfactorily, but the air-curable urethane adhesive composition cures smoothly. The portions that are difficult to come into contact with are characterized in that the curing is significantly delayed or, in some cases, is not cured.

For this reason, for example, when bonding non-moisture-permeable adherends over a large area or when using as a sealing agent with a large amount of application, about 1 to 1 mm from the outer peripheral surface that comes into contact with air.
Although it cures smoothly up to a distance of about 5 mm, the inside and the center, which are difficult to contact with air, are in an uncured state for a considerable period of time. The adhesive strength is poor, and there is a problem that defects such as poor appearance are liable to occur in the application part due to foaming due to carbon dioxide gas generated when the outer peripheral surface is cured.

[0006] In order to cope with the above problems of the moisture-curable urethane adhesive composition, various methods for suppressing foaming during moisture curing have been studied.
No. 31418 discloses that “a urethane prepolymer having an active isocyanate group, and a dehydration condensation product of an alicyclic diamine and a carbonyl compound, and an amine equivalent ratio to the isocyanate group of 0.2 to 0.6. And a moisture-curable polyurethane composition characterized by the following.

However, in the case of the polyurethane composition according to the above disclosure, there is no problem if it is a two-pack type, but if it is a one-pack type, the urethane prepolymer having an active isocyanate group and the amine coexist. There are problems such as poor storage stability and short open time during use, resulting in reduced workability. Also, for example, workability is particularly important in on-site construction applications. Therefore, it is strongly demanded that a one-pack type which does not require weighing or mixing is used, and a two-pack type is not practical. The composition is less than suitable.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems by uniformly and stably dispersing foaming due to carbon dioxide gas generated at the time of moisture curing in an adhesive layer. 1-part type that finally exhibits excellent adhesive strength even if the curing of the adhesive composition applied to a portion that is unlikely to come into contact with moisture is delayed, and that does not cause defects such as poor appearance in the applied portion. It is an object of the present invention to provide a moisture-curable urethane-based adhesive composition.

[0009]

The moisture-curable adhesive composition according to the invention described in claim 1 (hereinafter referred to as "first invention") is obtained by reacting a terminal hydroxyl group of a polyol with a polyfunctional isocyanate compound. Characterized in that 0.01 to 50 parts by weight of a foam stabilizer is contained with respect to 100 parts by weight of a urethane prepolymer having isocyanate groups at both ends obtained by the above method.

The moisture-curable adhesive composition according to the second aspect of the invention (hereinafter referred to as "second invention") is a moisture-curable adhesive composition according to the first aspect, wherein the foam stabilizer is silicone. It is a foam stabilizer.

[0011] The moisture-curable adhesive composition according to the invention of claim 3 (hereinafter referred to as "third invention") is the moisture-curable adhesive composition according to the first invention, wherein the polyol is a polyester polyol. There is a feature.

The moisture-curable adhesive composition according to the invention described in claim 4 (hereinafter referred to as “fourth invention”) is obtained by combining the moisture-curable adhesive composition according to the first invention with a urethane prepolymer. When the molar ratio (NCO / OH) of isocyanate groups to hydroxyl groups is less than 2.5, the foam stabilizer 0.01 to 100 parts by weight of the urethane prepolymer is used.
When the NCO / OH is 2.5 or more, 0.1 to 50 parts by weight of a foam stabilizer is contained.

The moisture-curable adhesive composition according to the invention of claim 5 (hereinafter referred to as “fifth invention”) is characterized in that the moisture-curable adhesive composition according to the first invention or the fourth invention is: The polyol is a polyester polyol, and the foam stabilizer is a silicone-based foam stabilizer.

The urethane prepolymer used as a main component of the moisture-curable adhesive composition according to the first invention is an isocyanate at both ends obtained by reacting a terminal hydroxyl group of a polyol with a terminal isocyanate group of a polyfunctional isocyanate compound. A compound having a group.

Depending on the type of polyol used, it is possible to obtain a urethane prepolymer that is liquid at room temperature or solid at room temperature. As a result, it is possible to obtain a moisture-curable adhesive composition that is liquid at room temperature or solid at room temperature. Becomes possible.

When the obtained moisture-curable adhesive composition is liquid at room temperature, it may be used as it is as a so-called solventless liquid adhesive, and the obtained moisture-curable adhesive composition may be used as it is. When solid at room temperature, it may be used by melting by heating as a so-called hot melt adhesive, or it may be dissolved in an organic solvent such as toluene, acetone, cyclohexane, dichloromethane, etc., and used as a so-called solvent-type adhesive You may.

The polyol used for synthesizing the urethane prepolymer, which is the main component of the moisture-curable adhesive composition according to the first invention, is not particularly limited.
For example, various polyols such as polyester polyols, polyether polyols, polyalkylene polyols, and polycarbonates can be mentioned, and are preferably used, and among them, polyester polyols having excellent physical properties after curing of the obtained urethane prepolymer are more preferably used. Can be

The above polyols may be used alone or in combination of two or more.

The polyester polyol is not particularly restricted but includes, for example, terephthalic acid, isophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid,
One or more polycarboxylic acids such as dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylenedicarboxylic acid and dodecamethylenedicarboxylic acid; Although not particularly limited, for example, ethylene glycol, diethylene glycol, propylene glycol,
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, 1,5-pentanediol,
Polyester polyol obtained by dehydrating and condensing one or more polyhydric alcohols such as 1,6-hexanediol, cyclohexanediol, etc .; Poly-ε-caprolactone obtained by ring-opening polymerization of ε-caprolactam Polyols and the like are mentioned, and are preferably used.

The above polyester polyols may be used alone or in combination of two or more.

The polyether polyol is not particularly limited, but may be, for example, a homopolymer such as ethylene glycol, propylene glycol, or tetramethylene glycol or a copolymer thereof; a low molecular weight having two or more active hydrogens. And / or a random copolymer of polyoxyethylene propylene polyol obtained by subjecting ethylene oxide and propylene oxide to ring-opening polymerization in the presence of one or more active hydrogen-containing compounds.
And block copolymers; polyoxytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran, and the like, and are preferably used.

The low-molecular-weight active hydrogen-containing compound having two or more active hydrogens is not particularly restricted but includes, for example, diols such as ethylene glycol, propylene glycol, butylene glycol and 1,6-hexanediol. Triols such as glycerin, trimethylolpropane, 1,2,6-hexanetriol;
Examples include amines such as ammonia, methylamine, ethylamine, propylamine, and butylamine, and one or more of these are suitably used.

The above polyether polyols may be used alone or in combination of two or more.

The molecular weight of the above polyether polyol is
Although not particularly limited, those having 500 to 15000 are preferable, and those having 1000 to 12000 are more preferable. The polyether polyol is not particularly limited, but preferably has 1.5 to 5 hydroxyl groups as an active hydrogen source in one molecule, more preferably 2 to 3 hydroxyl groups.

The polyalkylene polyol is not particularly restricted but includes, for example, polybutadiene polyol, hydrogenated polybutadiene polyol, polyisoprene polyol, hydrogenated polyisoprene polyol and the like, and are preferably used.

The above-mentioned polyalkylene polyols may be used alone or in combination of two or more.

The polycarbonate polyol is not particularly restricted but includes, for example, polyhexamethylene carbonate polyol and polycyclohexane dimethylene carbonate polyol.

The above polycarbonate polyols may be used alone or in combination of two or more.

The polyfunctional isocyanate compound used for synthesizing the urethane prepolymer which is the main component of the moisture-curable adhesive composition according to the first invention is not particularly limited. , Diphenylmethane diisocyanate (MDI), M
Mixtures of DI and triphenylmethane triisocyanate (crude MDI), liquid modified MDI, hexamethylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, cyclohexane phenylene diisocyanate, naphthalene-1,5-diisocyanate, and the like are preferable. MDI and Crude MD, which are excellent in safety and reactivity etc.
Liquid modified products of I and MDI are more preferably used.

The above polyfunctional isocyanate compounds may be used alone or in combination of two or more.

The method for synthesizing the urethane prepolymer used as the main component of the moisture-curable adhesive composition according to the first invention is not particularly limited, and one or more of the polyols described above and the polyfunctional isocyanate compound may be used. One or more kinds may be used, and the ratio of the isocyanate group in the polyfunctional isocyanate compound to the hydroxyl group in the polyol (NCO / OH) may be, for example, 1.2 to 15 in molar ratio,
Preferably mixed at a ratio of 2.5 to 12,
What is necessary is just to carry out by making it react at 60-100 degreeC for several hours.

The moisture-curable adhesive composition according to the first invention is characterized in that 0.01 to 50 parts by weight of a foam stabilizer is contained based on 100 parts by weight of the urethane prepolymer.

The above-mentioned foam stabilizer suppresses local aggregation of foaming due to carbon dioxide gas generated during moisture curing of the moisture-curable adhesive composition, and uniformly and stably disperses foaming in the adhesive layer. Any compound may be used as long as it is a compound to be obtained, and the type thereof is not particularly limited.

Specific examples of the foam stabilizer include, but are not particularly limited to, surfactants such as sulfate-type and sulfonate-type surfactants and silicone-based surfactants. Among them, a silicone surfactant having good affinity with the urethane prepolymer and exhibiting an excellent foam regulating effect is more preferably used.

The foam stabilizers may be used alone or in combination of two or more.

[0036] In the first invention, the content of the foam stabilizer is 0.0 to 100 parts by weight of the urethane prepolymer.
If the amount is less than 1 part by weight, it is difficult to uniformly and stably disperse the foam in the adhesive layer. Can not be prevented.

When the content of the foam stabilizer exceeds 50 parts by weight based on 100 parts by weight of the urethane prepolymer, the foam stabilizer acts as a softening agent, and the adhesiveness to the adherend, the adhesive strength, and the water resistance. , Heat resistance etc. decrease.

Next, the moisture-curable adhesive composition according to the second invention is characterized in that in the moisture-curable adhesive composition according to the first invention, the foam stabilizer is a silicone-based foam stabilizer. .

The silicone-based foam stabilizer is not particularly limited, but includes, for example, the silicone-based surfactants, and is preferably used.

The above-mentioned silicone-based surfactant has an affinity between a polyester portion or a polyether portion (urethane prepolymer portion) having an affinity for the polyester portion or the polyether portion in the urethane prepolymer skeleton and the urethane prepolymer. And a silicone portion (urethane-rough urethane prepolymer portion) having no, so that it has a so-called surfactant effect and exhibits an excellent foam-regulating effect.

The above-mentioned silicone foam stabilizers may be used alone or in combination of two or more.

Next, the moisture-curable adhesive composition according to the third invention is characterized in that, in the moisture-curable adhesive composition according to the first invention, the polyol is a polyester polyol.

The polyester polyol is not particularly restricted but includes, for example, terephthalic acid,
Dicarboxylic acids such as isophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, and dodecamethylene dicarboxylic acid One or more polyvalent carboxylic acids such as acids are not particularly limited. For example, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, A polyester polyol obtained by dehydrating and condensing one or more polyhydric alcohols such as neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, and cyclohexanediol;
And poly-ε-caprolactone polyol obtained by ring-opening polymerization of -caprolactam.

The above polyester polyols may be used alone or in combination of two or more.

By using a polyester polyol as the polyol component for synthesizing the urethane prepolymer, it is possible to obtain a moisture-curable adhesive composition which exhibits more excellent adhesive strength and impact resistance after curing.

Next, the moisture-curable adhesive composition according to the fourth invention is different from the moisture-curable adhesive composition according to the first invention in that the molar ratio of isocyanate groups to hydroxyl groups (NCO / When OH) is less than 2.5, 0.01 to 10 parts by weight of a foam stabilizer is contained with respect to 100 parts by weight of the urethane prepolymer,
When the NCO / OH is 2.5 or more, the foam stabilizer 0.1 to 5 is added to 100 parts by weight of the urethane prepolymer.
It is characterized by containing 0 parts by weight.

When the NCO / OH is less than 2.5, the amount of carbon dioxide gas generated when the urethane prepolymer is cured by moisture is relatively small, so that the content of the foam stabilizer is also relatively small. Preferably, the amount is small.

Even when NCO / OH is less than 2.5, if the content of the foam stabilizer is less than 0.01 part by weight based on 100 parts by weight of the urethane prepolymer, foaming due to carbon dioxide gas is caused in the adhesive layer. It becomes difficult to disperse uniformly and stably. Conversely, if the NCO / OH is less than 2.5, and if the content of the foam stabilizer exceeds 10 parts by weight with respect to 100 parts by weight of the urethane prepolymer, the foam regulating effect is no longer improved, It tends to decrease the adhesion to the adherend, adhesive strength, water resistance, heat resistance, and the like.

When the NCO / OH is 2.5 or more, the amount of carbon dioxide gas generated when the urethane prepolymer is cured by moisture is relatively large, so that the content of the foam stabilizer is also relatively low. It is preferable to use a large amount.

When the NCO / OH is 2.5 or more, if the content of the foam stabilizer is less than 0.1 part by weight based on 100 parts by weight of the urethane prepolymer, foaming due to carbon dioxide is uniformly formed in the adhesive layer. In addition, it is difficult to stably disperse. Conversely, even when the NCO / OH is 2.5 or more, if the content of the foam stabilizer exceeds 50 parts by weight based on 100 parts by weight of the urethane prepolymer, the foam regulating effect is no longer improved. In addition, the adhesiveness to the adherend, adhesive strength, water resistance, heat resistance, and the like are reduced.

Next, the moisture-curable adhesive composition according to the fifth invention is the moisture-curable adhesive composition according to the first invention or the fourth invention described above, wherein the polyol is a polyester polyol, and The foaming agent is a silicone-based foam stabilizer.

The polyester polyol is used as a polyol component at the time of synthesizing the urethane prepolymer, and
By using the silicone-based foam stabilizer as a foam stabilizer, a moisture-curable adhesive composition having a more excellent foam-controlling effect and exhibiting even more excellent adhesive strength and impact resistance after curing. Can be obtained.

The moisture-curable adhesive compositions according to the first to fifth inventions (hereinafter referred to as "the present invention") may be used with respect to the adherend, if necessary, within a range that does not impair the achievement of the object of the present invention. One or more kinds of tackifying resins and thermoplastic resins for improving adhesion and adjusting viscosity may be contained.

The tackifying resin which may be contained is not particularly limited, and examples thereof include a rosin resin, a hydrogenated rosin resin, a terpene resin, a hydrogenated terpene resin, and a terpene phenol resin. And various known tackifier resins such as aliphatic petroleum resins, alicyclic petroleum resins, and aromatic petroleum resins, and one or more of these resins are suitably used.

The softening point of the tackifying resin is not particularly limited, but is preferably 90 to 150 ° C. in a ring and ball softening point.

The content of the tackifier resin is not particularly limited, but may be a urethane prepolymer 100.
It is preferable that the amount of the tackifying resin is 200 parts by weight or less based on the weight part.

When the content of the tackifying resin with respect to 100 parts by weight of the urethane prepolymer exceeds 200 parts by weight, the heat resistance of the cured product of the obtained moisture-curable adhesive composition at a high temperature is reduced, or at a low temperature. In some cases, the elasticity may decrease and become brittle.

The thermoplastic resin which may be contained is not particularly limited.
And an ethylene-vinyl monomer copolymer having a melt index (MI) of 100 or more is preferably used.

Specific examples of the above-mentioned ethylene-vinyl monomer copolymer are not particularly limited. For example, ethylene-vinyl acetate copolymer (EVA), ethylene- (meth) acrylate copolymer , Ethylene-
(Meth) acrylic acid copolymers and the like.
Species or two or more species are suitably used. Here, “(meth) acryl” means “acryl” or “methacryl”.

The other thermoplastic resin which may be contained is not particularly limited.
One or more kinds of thermoplastic block rubbers such as BS, SIS, SEBS, and SEPS, and polyolefin resins such as polyethylene, polypropylene, and α-olefin copolymer may be used.

The content of the thermoplastic resin is not particularly limited, but is preferably not more than 100 parts by weight of the thermoplastic resin based on 100 parts by weight of the urethane prepolymer.

When the content of the thermoplastic resin exceeds 100 parts by weight with respect to 100 parts by weight of the urethane prepolymer, the moisture-curable adhesive composition has an advantage that the initial cohesive strength and the initial adhesive strength can be rapidly increased, The viscosity may be significantly increased and the workability during use may be reduced.

In addition to the urethane prepolymer and foam stabilizer as essential components, and the above-mentioned tackifying resin and thermoplastic resin to be contained as required, the moisture-curable adhesive composition according to the present invention comprises If necessary within the range not hindering the achievement of the task, for example, wax such as paraffin wax or microcrystalline wax, amine-based or organometallic compound-based curing acceleration catalyst, inorganic or organic filler,
Even if one or more of various additives such as a thickener, a thixotropic agent, a plasticizer, a softener, a coupling agent, a stabilizer, an antioxidant, an ultraviolet absorber, and a coloring agent are contained. good.

The amine-based curing accelerating catalyst is not particularly restricted but includes, for example, triethylamine, N
-Methylmorpholinebis (2-dimethylaminoethyl)
Ether, N, N, N ', N ", N" -pentamethyldiethylenetriamine, N, N, N'-trimethylaminoethyl-ethanolamine, bis (2-dimethylaminoethyl) ether, N-methyl, N'- Examples thereof include dimethylaminoethylpiperazine and an imidazole compound in which a secondary amine functional group in the imidazole ring is substituted with a cyanoethyl group. One or more of these are suitably used.

The filler is not particularly limited. For example, mica powder, calcium carbonate, surface-treated calcium carbonate, carbon black, talc, titanium oxide, rubber powder, organic balloon, inorganic balloon, wollastonite And one or more of these are preferably used.

The shape of the filler is not particularly limited, and may be any shape such as powder, scale, sphere, lump, and needle.

The thixotropic agent is not particularly restricted but includes, for example, colloidal silica, hydrogenated castor oil and organic bentonite.
Species or two or more species are suitably used.

Examples of the plasticizer include, but are not limited to, dioctyl phthalate (DOP), dibutyl phthalate, dilauryl phthalate, dioctyl adipate, diisodecyl adipate, tributyl phosphate, trioctyl phosphate, propylene glycol adipate polyester Butylene glycol adipate, epoxidized soybean oil, chlorinated paraffin, liquid paraffin, and the like. One or more of these are suitably used.

Examples of the stabilizer include, but are not limited to, “Tinuvin 327” (trade name, manufactured by Ciba Geigy), “Irganox 1010” (trade name, manufactured by Ciba Geigy), and “Tomithorp 800” (trade name). (Manufactured by Yoshitomi Pharmaceutical Co., Ltd.), and one or more of these are suitably used.

The method for producing the moisture-curable adhesive composition according to the present invention is not particularly limited. For example, a known stirring mixer such as a plast mill, a kneader, a Banbury mixer, or a roll equipped with a heating device may be used. Under an inert gas atmosphere such as nitrogen gas or under a reduced pressure dehydration atmosphere, etc., one or two or more predetermined amounts of urethane prepolymer as an essential component and one or two or more predetermined amounts of a foam stabilizer, One or more predetermined amounts of tackifying resin or thermoplastic resin to be contained as needed, and one or more predetermined amounts of one or more kinds of various additives to be contained as needed are uniformly stirred and mixed. Just do it. The order of mixing the above components is not particularly limited.

In the production of the above-mentioned moisture-curable adhesive composition, a polyol and a polyfunctional isocyanate compound are reacted to first produce a urethane prepolymer, and then other components are blended with the urethane prepolymer to form a uniform mixture. Of course, the procedure of stirring and mixing may be adopted, or, for example, first, the polyol and the other components such as the foam stabilizer and the inorganic or organic filler are uniformly stirred and mixed, and then the polyfunctional isocyanate compound is blended. , That is, a procedure for preparing a urethane prepolymer later.

The method of using the moisture-curable adhesive composition according to the present invention is not particularly limited. In this state, it may be applied to the adherend in various desired patterns such as a bead shape, a spiral shape, and a foam shape.

[0073]

The moisture-curable adhesive composition according to the present invention contains a specific amount of a foam stabilizer with respect to a specific amount of the urethane prepolymer as a main component. It is uniformly and stably dispersed in the adhesive layer. Therefore, the adhesive strength applied to the portion hardly contacted with air (moisture) is delayed due to the hardening of the adhesive composition or even when the adhesive composition is in an uncured state, foaming due to carbon dioxide gas is concentrated in the portion. Defects such as a decrease in appearance and poor appearance of the coated portion do not occur, and finally excellent adhesive strength and impact resistance are exhibited.

[0074]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight”.

(Example 1)

(1) Production of Moisture Curable Adhesive Composition Propylene glycol (molecular weight: 300
0, hydroxyl value 37) 1000 parts were put into a separable flask, and heated and melted at 120 ° C., then 700 mmHg
For 1 hour under reduced pressure. The melt is then
After adjusting the temperature to 0 ° C., 414 parts of MDI (trade name “Isonate 125M”, manufactured by Mitsubishi Kasei Dow) as a polyfunctional isocyanate compound and an amine-based catalyst (trade name “U-CAT2046”, manufactured by Sun Apro) as a curing promoting catalyst 10 parts were charged and reacted for 3 hours to obtain a urethane prepolymer (a) which contained a curing acceleration catalyst and was liquid at room temperature. The NCO / OH of the urethane prepolymer (a)
Was 5.0.

Next, 10 parts of a silicone surfactant (trade name “TFA4205”, manufactured by Toshiba Silicone Co., Ltd.) was added as a foam stabilizer to 100 parts of the urethane prepolymer (a) obtained above, and the mixture was uniformly mixed. The mixture was stirred and mixed to obtain a moisture-curable adhesive composition.

(2) Evaluation The performance (adhesive strength, expansion coefficient) of the moisture-curable adhesive composition obtained above was evaluated by the following methods. The results were as shown in Table 1.

Adhesion strength: 5% of the moisture-curable adhesive composition
One side was applied to a 0 mm × 50 mm (0.8 mm thick) pentite plate at an application amount of 300 g / m ² , and 20 seconds after the application, an uncoated pentite plate was overlapped and bonded to prepare an adhesion test piece. Next, the adhesive test piece obtained above was
Cured in an atmosphere of 65 ° C.-65% RH,
After 0 hour, the T-peel strength (N / cm) was measured.

Expansion coefficient: A moisture-curable adhesive composition was charged into a cylindrical polyethylene container having a diameter of 40 mm and a height of 8 mm, and cured for 72 hours in an atmosphere of 20 ° C. and 65% RH to form a column. A specimen was prepared by curing only the surface of the moisture-curable adhesive composition, and the height (A) of the cylinder was measured. Next, the test piece was put in an atmosphere of 80 ° C. for 8 hours, taken out, taken out, measured for the height (B) of the column after the input of 80 ° C., and the expansion rate (%) due to carbon dioxide gas was calculated by the following equation. did.

Example 2 In the production of a moisture-curable adhesive composition, 1000 parts of 1,6-hexaneadipate (having a hydroxyl value of 43) as a polyol was charged into a separable flask and heated and melted at 120 ° C. , 700mmH
Dehydrated under reduced pressure of 1 g for 1 hour. The melt is then
After the temperature was adjusted to 00 ° C., 193 parts of MDI (Isonate 125M) was added as a polyfunctional isocyanate compound, and the mixture was reacted for 3 hours to obtain a urethane prepolymer (b) solid at room temperature. The NCO / OH of the urethane prepolymer (b) was 2.0.

Next, 5 parts of a silicone surfactant (TFA4205) was added as a foam stabilizer to 100 parts of the urethane prepolymer (b) obtained above, and the mixture was uniformly melt-mixed to obtain a moisture-curable adhesive. Agent composition was obtained.

Comparative Example 1 In the production of a moisture-curable adhesive composition, a silicone surfactant (TFA4) was used as a foam stabilizer for 100 parts of the urethane prepolymer (a).
A moisture-curable adhesive composition was obtained in the same manner as in Example 1 except that the addition amount of 205) was 0.005 parts.

Comparative Example 2 In the production of a moisture-curable adhesive composition, a silicone surfactant (TFA4) was used as a foam stabilizer for 100 parts of the urethane prepolymer (a).
A moisture-curable adhesive composition was obtained in the same manner as in Example 1 except that the addition amount of 205) was changed to 60 parts.

Comparative Example 3 In the production of a moisture-curable adhesive composition, a silicone surfactant (TFA4) was used as a foam stabilizer for 100 parts of the urethane prepolymer (b).
A moisture-curable adhesive composition was obtained in the same manner as in Example 2 except that the addition amount of 205) was 0.005 parts.

Comparative Example 4 In the production of a moisture-curable adhesive composition, a silicone surfactant (TFA4) was used as a foam stabilizer for 100 parts of the urethane prepolymer (b).
A moisture-curable adhesive composition was obtained in the same manner as in Example 2 except that the addition amount of 205) was changed to 60 parts.

The performances (adhesion strength, adhesive strength) of the five types of moisture-curable adhesive compositions obtained in Example 2 and Comparative Examples 1-4.
(Expansion coefficient) was evaluated in the same manner as in Example 1. The results were as shown in Table 1.

[0088]

[Table 1]

As is clear from Table 1, the moisture-curable adhesive compositions of Examples 1 and 2 according to the present invention have an initial adhesive strength (after 4 hours of bonding) and a final adhesive strength (after 170 hours of bonding). Both were excellent. In addition, both moisture-curable adhesive compositions had low expansion coefficients, indicating that foaming due to carbon dioxide was uniformly and stably dispersed in the adhesive layer.

On the other hand, urethane prepolymer 100
In the moisture-curable adhesive compositions of Comparative Examples 1 and 3 in which the content of the foam stabilizer was less than 0.01 part by weight based on the weight, the final adhesive strength was lower than the initial adhesive strength. In addition, the coefficient of expansion was extremely high, indicating that foaming due to carbon dioxide gas was locally concentrated without foam regulation, indicating that the adhesive strength had decreased and severe expansion had occurred.

Further, the moisture-curable adhesive compositions of Comparative Examples 2 and 4 in which the content of the foam stabilizer was more than 50 parts by weight based on 100 parts by weight of the urethane prepolymer, showed an initial adhesive strength and a final adhesive strength. Were low, indicating an adverse effect when the content of the foam stabilizer was excessive.

[0092]

As described above, the moisture-curable adhesive composition according to the present invention can uniformly and stably disperse foaming due to carbon dioxide gas generated during moisture curing in the adhesive layer. An adverse effect can be prevented beforehand, so that a joined body having excellent initial adhesive strength and final adhesive strength and having a good appearance can be obtained.

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Claims (5)

[Claims] 1. A foam stabilizer is contained in an amount of 0.01 to 50 parts by weight based on 100 parts by weight of a urethane prepolymer having isocyanate groups at both ends obtained by reacting a terminal hydroxyl group of a polyol with a polyfunctional isocyanate compound. A moisture-curable adhesive composition comprising: 2. The moisture-curable adhesive composition according to claim 1, wherein the foam stabilizer is a silicone-based foam stabilizer. 3. The moisture-curable adhesive composition according to claim 1, wherein the polyol is a polyester polyol. 4. When the molar ratio of isocyanate groups to hydroxyl groups (NCO / OH) at the time of synthesizing the urethane prepolymer is less than 2.5, 0.01 to 10 parts by weight of the foam stabilizer relative to 100 parts by weight of the urethane prepolymer. Part is contained,
When the NCO / OH is 2.5 or more, the foam stabilizer 0.1 to 5 is added to 100 parts by weight of the urethane prepolymer.
The moisture-curable adhesive composition according to claim 1, wherein the composition contains 0 parts by weight. 5. The moisture-curable adhesive composition according to claim 1, wherein the polyol is a polyester polyol, and the foam stabilizer is a silicone-based foam stabilizer.