JPH093430A - One pack type wet-curable polyurethane adhesive - Google Patents

Abstract

PURPOSE: To obtain an adhesive capable of being used outdoors even under the conditions of high temperature and much moisture or in a rainy day, excellent in adhesive force, suitable for the uses of buildings, and not leaving carbon dioxide gas bubbles in cured coating films, when the adhesive is cured. CONSTITUTION: An one pack type wet-curable polyurethane adhesive comprises 100 pts.wt. of a polyurethane resin and 10-500 pts.wt. of at least a hydroxide selected from the group consisting of magnesium hydroxide, calcium hydroxide, and aluminum hydroxide. The hydroxide contains particles having particle diameters of <=5μm in an amount of >=70wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-pack type wet curable urethane adhesive. More specifically, the present invention relates to a one-component wet-curable urethane adhesive used in construction sites and the like, and particularly to an adhesive preferably used as an adhesive for construction of outdoor tile walls.

[0002]

2. Description of the Related Art In the field of construction, ceramic tiles, various decorative sheet-covered building materials, etc. are adhered to an adherend such as concrete or wood to decorate or protect the building. Various adhesives are used for this purpose.

In particular, for an adhesive used outdoors, it is important that it exerts its adhesive force even when the adherend such as concrete is wet by rain or the like, that is, it has excellent adhesiveness to the wet surface. . The one-pack type urethane adhesive is used for such an application, and is cured by the reaction between water contained in the air or the adherend and isocyanate which is a component in the adhesive.

A conventional urethane adhesive has a number average molecular weight of 500 to 10,000 and a 4,4'-diphenylmethylene resin on a polyester resin and / or a polyether resin having hydroxyl groups at both ends of the molecule. Diisocyanate (MDI) or Tolylene diisocyanate (T
It is based on a polyurethane isocyanate obtained by reacting a polyisocyanate compound having a functionality of two or more, such as DI). An adhesive is prepared by dispersing an inorganic material such as calcium carbonate or muscovite as a filler in such a base. As described above, such a one-pack type urethane adhesive reacts with the water contained in the air or the adherend, and cures while generating carbon dioxide gas.

However, when such an adhesive is used, the generated carbon dioxide gas tends to remain in the cured film. When the amount of carbon dioxide gas generated is large, many bubbles are confirmed in the cured film. In such a cured coating, the strength of the coating is not sufficient, so that the adhesive strength finally decreases. Therefore, such an adhesive must be handled with extreme caution when used under high temperature and high humidity and in the case of rain.

In JP-A-61-31418, isocyanate and amine are used in a molar equivalent ratio of 1: 0.2 to.
The use of 1: 0.6 reduces the amount of carbon dioxide gas generated and prevents the generation of bubbles. However, according to the disclosed technique, when amine and isocyanate are used together, the curing reaction of the urethane resin is too fast, and thus a one-component urethane adhesive having good workability cannot be obtained. As the adhesive used at the construction site, a one-component adhesive that does not require weighing and mixing is essential. Therefore, the adhesive disclosed here is not suitable as an adhesive for construction sites.

Further, in the above one-pack type moisture-curable urethane adhesive, carbon dioxide gas is further generated depending on the environmental conditions in which they are used, so that sufficient adhesive strength cannot be obtained. For example, under high temperature and high humidity conditions such as summer, the reaction between the isocyanate groups and water rapidly occurs, so that carbon dioxide gas is further generated in the cured coating until the end of curing, and as a result, the adhesive strength decreases. In addition to this, when the adherend is mortar or concrete, a large amount of water is contained therein, so that the amount of carbon dioxide gas generated increases. A similar phenomenon occurs when these adhesives are used outdoors and in rainy weather.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art. The object of the present invention is to prevent bubbles due to carbon dioxide gas from remaining in the adhesive coating and to improve the strength of the adhesive. It is to provide a urethane adhesive that does not deteriorate and is suitable for outdoor applications.

[0009]

The one-pack type wet-curable urethane adhesive of the present invention is selected from the group consisting of magnesium hydroxide, calcium hydroxide, and aluminum hydroxide based on 100 parts by weight of the urethane resin. A one-component wet-curable urethane adhesive containing at least one hydroxide of 10 parts by weight or more and 500 parts by weight or less, the hydroxide having a particle size of 5 μm or less. 7
It is contained in a proportion of 0% by weight or more. Thereby, the above object is achieved.

In a preferred embodiment, the hydroxide is
Particles having a particle size of 1 μm or less are contained in a proportion of 50% by weight or more.

The one-pack type moisture-curable urethane adhesive of the present invention is prepared by blending a hydroxide having a fine particle size with a urethane resin as a base.

(Urethane Resin) The urethane resin used in the present invention is a urethane resin obtained by reacting a polyol compound and a polyisocyanate compound.

Examples of the polyol compound which is a raw material of the urethane resin include polyether polyol, polyester polyol, hydroxyl group-containing polybutadiene polyol,
Acrylic polyols, castor oil derivatives, tall oil derivatives and the like can be used.

Among the above-mentioned polyol compounds, the polyether polyol is a homopolymer of propylene glycol, ethylene glycol or tetramethylene glycol or a copolymer thereof; a low molecular weight active hydrogen compound having two or more active hydrogens. Polyoxyethylene-propylene polyol random copolymer and / or block copolymer obtained by ring-opening polymerization of propylene oxide and ethylene oxide in the presence of one kind or two or more kinds; obtained by ring-opening polymerization of tetrahydrofuran There is polyoxytetramethylene glycol which is used.

Examples of the low molecular weight active hydrogen compound include diols such as ethylene glycol, propylene glycol, butylene glycol and 1,6-hexanediol;
Triols such as glycerin, trimethylolpropane, 1,2,6-hexanetriol; amines such as ammonia, methylamine, ethylamine, propylamine, butylamine may be used.

The molecular weight of the above polyether polyol is
500-10000, preferably 1000-5000
And has 1.5 to 5, preferably 2 to 3 hydroxy groups as an active hydrogen source in one molecule. As the urethane resin to be obtained, those having various molecular weights and functional groups can be used as long as the desired physical properties are not impaired. These may be used alone or in combination of two or more.

Among the polyol compounds which are the raw materials for the urethane resin, polyester polyols are generally prepared by reacting a polybasic acid with a polyhydric alcohol or by ring-opening polymerization of ε-caprolactone or the like with a polyhydric alcohol. It is an activated polyester polyol having a hydroxy group at the end, which can be prepared by

Examples of the polybasic acid component include phthalic acid, adipic acid, terephthalic acid, isophthalic acid, sebacic acid,
Dimerized linoleic acid, maleic acid, their di-lower alkyl esters and the like can be used. These can be used alone or in combination.

Examples of the polyhydric alcohol include diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol and dipropylene glycol; glycerin, trimethylolpropane, 1,2,2. Triols such as 6-hexanetriol, triethylene glycol, tripropylene glycol can be used. These can be used alone or in combination.

Specific examples of the above-mentioned polyester polyol include 1,4-butanediol / adipic acid, 1,
6-hexanediol / sebacic acid and the like can be used.

The number average molecular weight of such polyester polyol is 500 to 10,000, preferably 1,0.
The range is from 00 to 5,000. Number average molecular weight is 500
If the amount is less than 10,000, the resulting adhesive lacks flexibility and is 10,000.
If it exceeds, the adhesive obtained will lack toughness.

The polyol compounds including such polyether polyols and polyester polyols may be used alone or in admixture of two or more, depending on the desired characteristics of the urethane adhesive used.

Examples of the polyisocyanate compound which is a raw material of the urethane resin include aliphatic polyisocyanates such as hexamethylene diisocyanate and lysine methyl ester diisocyanate; hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate and hydrogenated tolylene isocyanate. Alicyclic polyisocyanates; aromatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, xylylene diisocyanate; and mixtures thereof can be used. From the viewpoint of easy handling, TDI and MD are preferable.
Aromatic polyisocyanates such as I can be used.

The urethane resin used in the present invention is a urethane resin obtained by reacting a homopolymer of propylene glycol, ethylene glycol or tetramethylene glycol or a copolymer of these glycols with TDI or MDI. preferable. A urethane resin obtained by reacting polypropylene glycol and MDI is preferable from the viewpoint of the adhesive strength of the obtained adhesive. Dibasic acids such as adipic acid, succinic acid, phthalic acid,
Polyester polyol obtained by reaction with ethylene glycol, butanediol, etc. and TDI or MD
Urethane resins obtained by reacting with I are also preferred.

The urethane resin used in the present invention is prepared by mixing the above-mentioned polyol compound and polyisocyanate compound under non-aqueous conditions and heating them if necessary. Usually, the urethane resin is formed by heating at 40 ° C. to 150 ° C. for 2 hours to 18 hours.

The chemical equivalent of the isocyanate group of the polyisocyanate compound used for the preparation of such a urethane resin is in excess of the chemical equivalent of the hydroxyl group of the polyol compound in consideration of the isocyanate that reacts with water contained in the raw material. Is desirable. When the chemical equivalent of the isocyanate group of the polyisocyanate compound is equal to or less than the chemical equivalent of the hydroxyl group of the polyol compound, the adhesive force of the resulting resin is substantially lost.

The degree of crosslinking of the urethane resin thus formed varies depending on the number of functional groups of the polyisocyanate compound used, but the degree of crosslinking is such that the resulting adhesive has sufficient heat resistance and water resistance. Is important to achieve.

(Hydroxide) The hydroxide used in the present invention is
It is at least one selected from the group consisting of calcium hydroxide, magnesium hydroxide and aluminum hydroxide.

The hydroxide preferably has a small particle size. As used herein, "particle size" is the average particle size measured by the light scattering method. The hydroxide has particles with a particle size of 5 μm or less, and is 70
Particles having a particle size of 5% by weight or more, preferably 5% or less,
70% by weight or more based on the weight of all hydroxides and a particle size of 1
40% by weight or more of particles of μm or less, more preferably,
70% by weight or more of particles having a particle size of 5 μm or less and 50% by weight or more of particles having a particle size of 1 μm or less based on the weight of all hydroxides. 7 hydroxides with a particle size of 5 μm
If it is 0% by weight or less, the generated carbon dioxide gas will not be sufficiently adsorbed by the hydroxide and cannot be converted into a carbonate salt, resulting in poor adhesive strength.

The hydroxide is based on the urethane resin 100.
It may be contained in an amount of 10 to 500 parts by weight, preferably 20 to 200 parts by weight, based on parts by weight. 1
If the amount is less than 0 parts by weight, the resulting urethane adhesive has poor adhesive strength. If it exceeds 500 parts by weight, the resulting adhesive becomes brittle.

(Additive) The urethane adhesive of the present invention comprises:
If necessary, within a range that does not deteriorate the properties of the urethane adhesive of the present invention, an inorganic filler, an adhesion-imparting agent, a solvent and a plasticizer for decreasing the viscosity of the entire adhesive, a curing-accelerating catalyst, an antiaging agent. , Pigments, etc. may be added as additives.

As the inorganic filler, calcium carbonate, mica, silica sand, cement and the like can be used.

As the adhesion-imparting agent, a conventionally known silane coupling agent, titanate coupling agent, alkyleneimine or the like can be used.

As the plasticizer, dioctyl phthalate,
Phthalates such as butylbenzyl phthalate and dinonyl phthalate; benzoates such as diethylene glycol dibenzoate and ethylene glycol monobutyl ether benzoate; partially hydrogenated terphenyls, alkyl polycyclic aromatic hydrocarbons; chlorinated paraffins Can be used.

As the solvent, aromatic hydrocarbons such as toluene and xylene, esters, ketones and ethers can be used.

As the curing-accelerating catalyst, N-alkylbenzylamine, N-alkylmorpholine, N-alkylaliphatic polyamine, N-alkylpiperazine, triethylenediamine, heavy metal salts of naphthenic acid or octenoic acid (tin, lead, cobalt). , Salts of manganese, iron, etc.), dibutyltin dilaurate, dibutyltin maleate and the like.

In addition, silicic acid anhydride, an antioxidant, an ultraviolet absorber, an anti-sagging agent and the like may be added as additives.

The above-mentioned various additives may be added and mixed at the time of mixing the polyol compound and the hydroxide or after the preparation of the urethane resin, if necessary.

(Preparation of Urethane Adhesive) The adhesive of the present invention containing a urethane resin is prepared, for example, by the following method. The above hydroxide and, if necessary, an additive are added to the above polyol compound, and the mixture is added at 60 ° C. to 150 ° C. for 2 hours to 1
It is dehydrated by heating under reduced pressure for 8 hours, if necessary, and a polyisocyanate compound is added thereto. By heating this mixture at 40 ° C. to 150 ° C. for 2 hours to 18 hours as required, the adhesive of the present invention containing a urethane resin is obtained.

Alternatively, first, the above-mentioned polyol compound and polyisocyanate compound are mixed and, if necessary, additives are added, followed by heating at 60 ° C. to 150 ° C. for 2 hours to 18 hours and under reduced pressure as necessary. Then, a urethane resin is prepared by reacting while dehydrating. The above-mentioned hydroxide is added to the obtained urethane resin and sufficiently mixed by stirring to obtain the adhesive of the present invention containing the urethane resin.

[0041]

The one-component moisture-curable adhesive of the present invention contains at least one hydroxide selected from magnesium hydroxide, aluminum hydroxide and calcium hydroxide having a predetermined small particle size. As a result, carbon dioxide gas bubbles do not remain in the adhesive coating. That is, since the carbon dioxide gas generated during curing due to the reaction between the isocyanate group of the urethane resin and water is adsorbed on the hydroxide, and / or part of the adsorbed carbon dioxide gas is on the hydroxide. Since it reacts with to form carbonate, carbon dioxide gas bubbles do not remain in the adhesive coating. As a result, the adhesive strength does not decrease even under high temperature and high humidity or in the rain, or even when the surface of the adherend is wet with water.

[0042]

The present invention will be specifically described with reference to the following examples, but the present invention is not limited thereto.
In this specification, all "parts" are by weight unless otherwise specified.

Example 1 100 parts of propylene glycol (number average molecular weight 3,000) and 2 parts of calcium carbonate
00 parts, 50 parts of calcium hydroxide containing particles having a particle size of 5 μm or less at a ratio of 90% by weight, and 70 parts of dioctyl phthalate as a plasticizer were added and mixed, and a reduced pressure condition of 10 mHg was applied at 110 ° C. for 3 hours. Water was removed by heating below. Then add 8 MDI to this mixture.
By adding 0 part and reacting at 120 ° C. for 3 hours,
A one-component moisture-curable urethane adhesive was obtained.

(Example 2) 9 particles having a particle size of 5 μm or less were used.
50% by weight of magnesium hydroxide containing 5% by weight and 70% by weight of particles having a particle size of 1 μm or less.
A one-pack type moisture-curable urethane adhesive was obtained in the same manner as in Example 1 except that the parts were used.

(Example 3) 9 particles having a particle size of 5 μm or less were used.
50% of aluminum hydroxide containing 0% by weight and 60% by weight of particles having a particle size of 1 μm or less.
A one-pack type moisture-curable urethane adhesive was obtained in the same manner as in Example 1 except that the parts were used.

Comparative Example l A one-pack type moisture-curable urethane adhesive was obtained in the same manner as in Example 1 except that 50 parts of calcium carbonate was used instead of calcium hydroxide.

Comparative Example 2 A one-pack type moisture-curable urethane adhesive was obtained in the same manner as in Example 1 except that 10 parts of calcium hydroxide was used.

(Comparative Example 3) 5 particles having a particle size of 5 μm or less were used.
A one-pack type moisture-curable urethane adhesive was obtained in the same manner as in Example 1 except that 0% by weight of calcium hydroxide was used.

(Evaluation of Adhesive) The adhesives obtained in the above Examples and Comparative Examples were evaluated for the following items. (1) Adhesion 10 cm × 1 after being immersed in water for 1 day and then wiped off the water
Six slate plates having a size of 0 cm were prepared, and the one-pack type urethane adhesive obtained in each of the above Examples and Comparative Examples was applied to each slate plate at a thickness of 800 g / m ² . Then, a test piece was obtained by sticking a 6 cm × 6 cm tile on the adhesive-coated surface. After curing this test piece for 48 hours under the condition of 20 ° C. and relative humidity of 60%, an autograph (manufactured by Shimadzu Corporation, AGS-100)
Was used to pull at a pulling speed of 1 mm / min perpendicularly to the tile to measure the plane pulling force.

(2) Presence / absence of air bubbles Each test piece after curing for 48 hours was cut, and the cross section of the adhesive was visually inspected and with a lens in the adhesive coating of each test piece.
The presence or absence of air bubbles having a diameter of 1 mm or more was confirmed.

Table 1 shows the results.

[0052]

[Table 1]

As can be seen from Table 1, any one of magnesium hydroxide, calcium hydroxide, and aluminum hydroxide containing 70% by weight or more of particles having a particle diameter of 5 μm or less was added to 100 parts of the urethane resin. The urethane adhesives of Examples 1 to 3 containing 10 parts or more of
No bubbles remain in the adhesive coating. Further, Examples 1 to 3
The urethane resin of Comparative Example 1 has the same particle size, but uses a carbonate adhesive instead of a hydroxide in Comparative Example 1, and contains a hydroxide in a ratio of less than 10 parts with respect to the urethane resin. The urethane adhesive of Example 2 and a particle size of 5
The adhesive strength is superior to that of the urethane adhesive of Comparative Example 3 in which the content of particles of μm or less is less than 70% by weight.

[0054]

EFFECTS OF THE INVENTION The one-pack type moisture-curable urethane adhesive of the present invention has no residual carbon dioxide gas bubbles in the adhesive coating, is excellent in adhesive strength, and does not deteriorate in adhesive strength over time. The one-pack type moisture-curable urethane adhesive of the present invention has an excellent adhesive force with a wet surface, and has an excellent adhesive force even under a high humidity condition even when used outdoors.

Claims (2)

[Claims] 1. 10 parts by weight or more and 500 parts by weight or less of at least one hydroxide selected from the group consisting of magnesium hydroxide, calcium hydroxide, and aluminum hydroxide with respect to 100 parts by weight of a urethane resin. A one-component wet-curable urethane adhesive containing at a ratio of 70 wt% or more, the hydroxide containing particles having a particle size of 5 μm or less. adhesive. 2. The hydroxide contains particles having a particle diameter of 1 μm or less in a proportion of 50% by weight or more.
The one-component wet-curable urethane adhesive described in 1.