JPH11209733A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one-pack type adhesive composition capable of manifesting a stabilized excellent adhesive strength even under a severe condition by uniformly distributing foam in the adhesive layer by including a specific urethane polymer and a specified inorganic spherical material in a specific proportion. SOLUTION: The objective composition comprises (A) a urethane prepolymer having isocyanate groups at both ends, (B) >=5 pts.wt., preferably 10-300 pts.wt. inorganic spherical material having 10-500 μm, preferably 100-300 μm average particle diameter based on 100 pts.wt. component A, and (C) optionally, a silane coupling agent as an adhesiveness-imparting agent, an amine-based catalyst as a hardening-promoting catalyst, a filler, a thixotropy-providing agent, a coloring agent, a plasticizer (a softener), a stabilizer, an ultraviolet absorbent, an organic solvent or the like. The component A is a reaction product of a polyhydroxy compound and a polyisocyanate compound. A hollow ceramic or the like is preferably used as the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a one-pack type moisture-curable urethane resin-based adhesive composition.

[0002]

2. Description of the Related Art In recent years, a one-pack type moisture-curable urethane resin-based adhesive has been used in general because it has simple workability and exhibits a well-balanced performance after curing. It is widely used as an on-site construction adhesive for construction and civil engineering, as well as various industrial adhesives, instead of a solvent-based adhesive or a two-component mixed epoxy resin adhesive. In particular, recently, demand for the adhesive for on-site construction of floor materials, wall panel materials, ceiling materials and the like has been increasing.

However, the moisture-curable urethane resin-based adhesive generates carbon dioxide gas when it cures by reacting with moisture in an adherend or moisture in an atmosphere, and foams. Is insufficient. This phenomenon is particularly remarkable in the case of on-site construction applications such as construction or civil engineering where it is difficult to control the moisture content in the adherend or the humidity in the atmosphere, etc. Problems often occur such as a decrease in strength and a decrease in adhesive strength due to insufficient cohesion of the cured product due to foaming in the adhesive layer.

To cope with the problems caused by foaming during curing of the moisture-curable urethane resin-based adhesive, various methods for suppressing foaming have been studied.
In the publication No. 0-188455, "based on 100 parts by weight of a mixture of a prepolymer having a terminal isocyanate group and a plasticizer, a filler and other auxiliaries as required,
A moisture-curable one-component polyurethane composition characterized by adding 0.5 to 10 parts by weight of a dispersion of finely divided calcium oxide "has been proposed.

The method according to the above proposal is based on the idea that foaming is suppressed by adding fine powdered calcium oxide to a urethane prepolymer and reacting carbon dioxide gas generated during curing with fine powdered calcium oxide to convert it to calcium carbonate. And

[0006] However, in the case of the method according to the above proposal, when the adherend has a high water content or in a high temperature and high humidity atmosphere,
The reaction between urethane prepolymer and water is accelerated, and the amount of carbon dioxide gas generated per unit time increases, and the conversion of calcium oxide to calcium carbonate cannot catch up with the generation of carbon dioxide gas. Therefore, there remains a problem that a sufficient foam suppressing effect cannot be obtained.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention does not suppress foaming at the time of curing, but uniformly disperses foaming in an adhesive layer to obtain a water content. One-part moisture curing that can exhibit stable and excellent adhesive strength and elasticity even under severe bonding conditions, such as when using a large amount of adherends or when used in a hot and humid atmosphere. It is an object to provide a urethane resin-based adhesive composition.

[0008]

The adhesive composition according to the present invention has an average particle size of 10 to 500 based on 100 parts by weight of a urethane prepolymer having isocyanate groups at both ends.
It is characterized by containing at least 5 parts by weight of an inorganic spherical material of μm.

The urethane prepolymer having isocyanate groups at both ends which is used as a main component in the adhesive composition according to the present invention is a polymer which is cured by forming a urea bond by reacting isocyanate groups with water to form a polymer. And a reaction product obtained by reacting a polyhydroxy compound with a polyisocyanate compound.

The polyhydroxy compound used for producing the urethane prepolymer is not particularly limited, but includes polyether polyols, polyester polyols, and polymer polyols generally used for producing urethane compounds. And it is preferably used.

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

The polyether polyol is not particularly limited. For example, a polymer obtained by subjecting an alkylene oxide to ring-opening polymerization in the presence of a low-molecular-weight active hydrogen compound having two or more active hydrogens may be used. And preferably used

Specific examples of the low-molecular-weight active hydrogen compound having two or more active hydrogens are not particularly limited. For example, bisphenol A, ethylene glycol, propylene glycol, butylene glycol,
Diols such as 1,6-hexanediol; triols such as glycerin and trimethylolpropane; and amines such as ethylenediamine and butylenediamine are preferably used.

The low molecular weight active hydrogen compounds having two or more active hydrogens may be used alone or in combination of two or more.

Further, specific examples of the above-mentioned alkylene oxide are not particularly limited. For example, ethylene oxide, propylene oxide, butylene oxide, amylene oxide, hexylene oxide,
Tetrahydrofuran and the like are mentioned, and are preferably used.

The above-mentioned alkylene oxides may be used alone or in combination of two or more.

The polyester polyol is not particularly limited, but may be, for example, adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid,
Dehydration condensation of polybasic acid such as succinic acid and polyhydric alcohol such as bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexane glycol, neopentyl glycol Lactone polymers such as ε-caprolactone and α-methyl-ε-caprolactone; castor oil, hydroxycarboxylic acids such as reaction products of castor oil and ethylene glycol, and the above polyhydric alcohols and the like. And the like, and are preferably used.

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

The polymer polyol is not particularly limited. For example, the above-mentioned polyether-based polyol or polyester-based polyol is graft-polymerized with an ethylenically unsaturated compound such as acrylonitrile, styrene or methyl (meth) acrylate. Obtained graft polymer; 1,2-polybutadiene polyol, 1,4
-Polybutadiene polyol or a hydrogenated product thereof is preferably used.

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

The weight average molecular weight of the polymer polyol is not particularly limited, but may be 100 to 50.
It is preferably about 000, more preferably about 500 to 5000.

The polyisocyanate compound used for the production of the urethane prepolymer is not particularly limited, but 2,4-tolylene diisocyanate, phenylene diisocyanate, xylene diisocyanate, 4,4'-diphenylmethane diisocyanate (M
DI), a mixture of MDI and triphenylmethane triisocyanate (crude MDI), 1,5-naphthylene diisocyanate, isophorone diisocyanate,
Dicyclohexylmethane diisocyanate, ethylene diisocyanate, methylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, triphenylmethane triisocyanate and hydrogenated products thereof, and the like are preferably used. Among them, MDI excellent in safety, reactivity, etc. And Crude MDI
Is more preferably used.

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

The method for producing the urethane prepolymer used in the adhesive composition according to the present invention is not particularly limited. For example, the polyhydroxy compound and the polyisocyanate compound are reacted with the hydroxyl group (OH) of the polyhydroxy compound. Isocyanate group (NCO) ratio of polyisocyanate compound (NCO / OH)
Are mixed at an equivalent ratio of 1.2 to 15, preferably 3 to 12, and reacted in a nitrogen stream at a temperature of about 80 to 100 ° C. for about 3 to 5 hours to obtain a desired compound. A urethane prepolymer can be obtained.

If the above-mentioned NCO / OH is less than 1.2 in equivalent ratio, the viscosity of the obtained urethane prepolymer becomes too high, and it may be difficult to prepare an adhesive composition. When the / OH exceeds 15 in equivalent ratio, the obtained adhesive composition tends to foam at the time of curing, the cohesive strength of the cured product is reduced, and sufficient adhesive strength may not be obtained.

The adhesive composition according to the present invention has an average particle size of 10 to 50 parts by weight based on 100 parts by weight of the urethane prepolymer having isocyanate groups at both ends, which is the main component.
It contains at least 5 parts by weight of a 0 μm inorganic sphere.

By uniformly containing the above-mentioned inorganic spheres in the adhesive composition, carbon dioxide gas generated during curing is collected at the interface between the urethane prepolymer and the inorganic spheres, and is uniformly dispersed in the adhesive layer. Therefore, after curing, it becomes a cured product that is uniformly foamed with inorganic spheres as nuclei, and is subjected to severe bonding conditions such as when it is used for adherends with a high water content or when it is used under high temperature and high humidity atmosphere However, stable and excellent adhesive strength and elasticity can be exhibited.

The inorganic spherical material may be any inorganic spherical material whose surface is not treated with an organic material, and is not particularly limited. Examples thereof include hollow ceramics, ceramic balls (spherical ceramics), spherical glass, Glass balloons and the like are mentioned, and are preferably used. Among them, hollow ceramics, which are advantageous in terms of cost, are more preferably used.

The inorganic spheres may be used alone or in combination of two or more.

In the adhesive composition according to the present invention, it is necessary that the average particle diameter of the inorganic sphere is 10 to 500 μm, preferably 100 to 300 μm.

If the average particle size of the inorganic spherical material is less than 10 μm, it becomes difficult to form a uniformly foamed cured product, and thus the dispersion of the adhesive strength tends to increase. Conversely, the average particle size of the inorganic spherical material is 500 μm. If the amount exceeds the above range, the inorganic spheres function as spacers, causing inconvenience when it is desired to reduce the amount of application, or rather, lowering the adhesive strength.

In the adhesive composition according to the present invention, 100 parts by weight of the urethane prepolymer having isocyanate groups at both terminals described above is added to the above-mentioned average particle diameter of 1 part by weight.
It is necessary to contain at least 5 parts by weight, preferably 10 to 300 parts by weight of inorganic spheres of 0 to 500 μm.

If the content of the inorganic spheres is less than 5 parts by weight with respect to 100 parts by weight of the urethane prepolymer, it becomes difficult to uniformly disperse the carbon dioxide gas generated during curing, and consequently the adhesive strength varies. growing.
On the other hand, when the content of the inorganic spheres exceeds 300 parts by weight with respect to 100 parts by weight of the urethane prepolymer, the cohesive strength of the cured product may be reduced and the adhesive strength may be reduced.

In the adhesive composition according to the present invention, in addition to the urethane prepolymer having isocyanate groups at both terminals, which are essential components, and inorganic spheres having an average particle diameter of 10 to 500 μm, a range that does not impair the achievement of the object of the present invention. If necessary, a silane coupling agent as an adhesion-imparting agent, an amine-based catalyst as a curing accelerator, a filler, a thixotropy-imparting agent, a coloring agent, a plasticizer (softening agent), a stabilizer, an antioxidant And one or more of various additives such as an ultraviolet absorber and an organic solvent.

The silane coupling agent is not particularly restricted but includes, for example, aminoalkoxysilanes such as γ-aminomethyltriethoxysilane and N-β (aminoethyl) -γ-aminopropyltrimethoxysilane; mercaptoalkoxysilanes such as γ-mercaptopropyltrimethoxysilane; epoxyalkoxysilanes such as γ-glycidoxypropyltrimethoxysilane and 3,4-epoxycyclohexylethyltrimethoxysilane; vinyltris (β-methoxyethoxy) silane; Vinyl silanes such as ethoxy silane; silane compounds having one isocyanate group and one alkoxysilyl group such as γ-isocyanatopropyltriethoxy silane; one or more of these are suitably used.

Examples of the amine catalyst include, but are not particularly limited to, triethylamine, N-methylmorpholine bis (2-dimethylaminoethyl) ether, N, N, N ', N "-pentamethyldiethylenetriamine, N, N, N'-trimethylaminoethylethanolamine, bis (2-dimethylaminoethyl) ether, N-methyl-N'-dimethylaminoethylpiperazine, secondary amine function in imidazole ring substituted with cyanoethyl group And the like, and 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 thixotropy-imparting agent is not particularly restricted but includes, for example, colloidal silica, hydrogenated castor oil, organic bentonite and the like.
Species or two or more species are suitably used.

The plasticizer is not particularly restricted but includes, for example, 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 particularly 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 organic solvent is not particularly restricted but includes, for example, synthetic isoparaffinic solvents having a flash point of 40 ° C. or higher, and one or more of these are preferably used.

The method for producing the adhesive composition according to the present invention comprises:
Without being special, for example, using a conventionally known mixer such as a plast mill, kneader, Banbury mixer, roll, etc., under an inert gas atmosphere such as nitrogen gas or under a reduced pressure dehydration atmosphere, etc. A predetermined amount of the urethane prepolymer and the inorganic spheres, and a predetermined amount of one or more of the above-mentioned various additives added as needed may be uniformly stirred and mixed.

The adhesive composition according to the present invention is particularly preferably used for on-site construction such as construction and civil engineering, but is not limited to these uses, and may be used for factory-produced building materials, woodwork, furniture, and the like. It is also suitably used for various industrial uses such as for automobiles and electric machines, and for general use.

[0044]

The adhesive composition according to the present invention comprises a urethane prepolymer having isocyanate groups at both ends as a main component, and a specific amount of inorganic spheres having a specific average particle diameter is contained. The carbon dioxide gas generated at the time gathers at the interface between the urethane prepolymer and the inorganic spheres and is uniformly dispersed in the adhesive layer, and after curing, becomes a cured product uniformly foamed with the inorganic spheres as nuclei. Therefore, even under severe bonding conditions such as when an adherend having a high water content is used or when used in a high-temperature and high-humidity atmosphere, stable and excellent bonding strength and elasticity are exhibited.

[0045]

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

Preparation of inorganic spheres and silica sand: Four types of inorganic spheres and silica sand No. 1 shown in Table 1 below were prepared.

[0047]

[Table 1]

(Example 1)

(1) Preparation of urethane prepolymer A weight-average molecular weight of 2 was set so that NCO / OH = 7.4.
000 polypropylene glycol and 50 parts of crude MDI (trade name “44V-20”, manufactured by Sumitomo Bayer Urethane Co., Ltd.) at 90 ° C. for 5 hours in a nitrogen gas atmosphere to obtain an NCO content of 7.5%. A urethane prepolymer having isocyanate groups at both ends was obtained.

(2) Preparation of Adhesive Composition To 100 parts of the urethane prepolymer obtained above,
Heavy calcium carbonate treated with surface fatty acid
C ", Shiraishi Calcium Industry Co., Ltd.) 50 parts, heavy calcium carbonate (trade name" SS # 30 ", Nitto Powder Chemical Co., Ltd.) 1
00 parts, 30 parts of a plasticizer (DOP) and 0.05 parts of N-methylmorpholine bis (2-dimethylaminoethyl) ether as a curing accelerator are added, and the mixture is uniformly stirred and mixed under reduced pressure to obtain a viscosity (20 ° C.). ) A composition of 20000 mPa · s was obtained. Then, the composition 280.05 obtained above was obtained.
28 parts of the inorganic spherical material (A) was added to the mixture, and the mixture was uniformly stirred and mixed to obtain an adhesive composition. In addition, "white luster flower C
C "," SS # 30 ", and DOP
What was subjected to dehydration under reduced pressure for a time was used.

(3) Evaluation The performance of the adhesive composition obtained above was evaluated by the following method. The results were as shown in Table 2. The evaluation was performed in an atmosphere of 20 ° C. and 65% RH unless otherwise specified.

Preparation of Adhesion Test Specimen A concrete plate (70 mm × 70 mm × 20 mm) was
After being immersed in water at 0 ° C. for one week, it was taken out and lightly wiped on the surface, and immediately applied with the adhesive composition obtained above using a comb iron so that the coating amount was 400 g / m ² . Then, a birch material (40 mm × 40 mm × 5 mm) whose moisture content has been adjusted to 15% in advance is attached and 10 g
/ Cm ² for 10 seconds, remove the load, leave as it is in an atmosphere of 30 ° C. and 70% RH for 7 seconds.
After curing for days, an adhesion test piece was prepared.

Measurement of Tensile Strength After the adhesive test piece obtained above was allowed to stand in an atmosphere of 20 ° C. and 65% RH for 6 hours, an autograph (manufactured by Shimadzu Corporation) was used under the same atmosphere, and the adhesive test piece was applied to the adhesive surface. 5 vertically
mm / min, tensile strength (kg / c
m ² ) was measured. At the same time, the destruction state (material destruction, interfacial delamination, cohesive destruction) and the foaming state of the fractured surface were visually observed, and the overall evaluation was performed together with the tensile strength.

Example 2 As shown in Table 2, except that in the preparation of the adhesive composition, 5.6 parts of inorganic spheres (B) were added instead of 28 parts of inorganic spheres (A). In the same manner as in Example 1, an adhesive composition and an adhesive test piece were obtained.

Example 3 As shown in Table 2, except that in the preparation of the adhesive composition, 5.6 parts of inorganic spheres (C) were added instead of 28 parts of inorganic spheres (A). In the same manner as in Example 1, an adhesive composition and an adhesive test piece were obtained.

(Comparative Example 1) As shown in Table 2, in the preparation of the adhesive composition, the amount of the inorganic spheres (A) was set at 2.
An adhesive composition and an adhesive test piece were obtained in the same manner as in Example 1 except that the amount was 8 parts.

Comparative Example 2 As shown in Table 2, except that 5.6 parts of inorganic spheres (D) were added instead of 28 parts of inorganic spheres (A) in the preparation of the adhesive composition. In the same manner as in Example 1, an adhesive composition and an adhesive test piece were obtained.

(Comparative Example 3) As shown in Table 2, in the preparation of the adhesive composition, 5.6 parts of silica sand No. 1 was added instead of 28 parts of the inorganic spheres (A). In the same manner as in Example 1, an adhesive composition and an adhesive test piece were obtained.

Using the five types of adhesive test pieces obtained in Examples 2 and 3 and Comparative Examples 1 to 3, the tensile strength was measured in the same manner as in Example 1. The results were as shown in Table 2.

[0060]

[Table 2]

As is apparent from Table 2, the adhesive compositions of Examples 1 to 3 according to the present invention adhere a high moisture content concrete plate and a birch material to a high temperature and high humidity (30 ° C.-70% R).
Excellent adhesive strength (tensile strength) even when cured under H)
And the destruction state was birch material destruction, which was excellent. The foamed state of the fractured surface was uniform, indicating that the carbon dioxide gas generated during curing was uniformly dispersed in the adhesive layer.

On the other hand, urethane prepolymer 100
The adhesive composition of Comparative Example 1 in which the content of the inorganic spheres (A) was less than 5 parts by weight relative to parts by weight, or the comparative example containing the inorganic spheres (D) having an average particle diameter of more than 500 μm. Adhesive strength (tensile strength) of each of the adhesive compositions of No. 2 was low, and the destruction state was cohesive failure, and did not lead to material (birch material) failure. Further, the foamed state of the fractured surface was non-uniform, indicating that the carbon dioxide gas generated at the time of curing was not uniformly dispersed in the adhesive layer, which caused a decrease in the adhesive strength.

Further, the adhesive composition of Comparative Example 3 containing silica sand No. 1 without containing the inorganic spheres had a substantially uniform foaming state of the fractured surface, but had an adhesive strength (tensile strength). It was quite low, and the failure state was cohesive failure, which was not a favorable result.

[0064]

As described above, the adhesive composition according to the present invention can be used under severe bonding conditions, such as when an adherend having a high water content is used or when used in an atmosphere of high temperature and high humidity. Even underneath, it exhibits excellent adhesive strength and elasticity stably, so it can be used in various industries such as construction and civil engineering, as well as factory-produced building materials, woodwork, furniture, automobiles, and electrical equipment. It is also suitably used for applications and general purposes.

Claims (1)

[Claims] An average particle diameter of 10 parts by weight based on 100 parts by weight of a urethane prepolymer having isocyanate groups at both ends.
An adhesive composition comprising at least 5 parts by weight of an inorganic sphere having a size of from 500 to 500 μm.