JPH0873830A - Production of urethane-based water-base adhesive - Google Patents

Abstract

PURPOSE: To obtain the subject adhesive excellent in dispersion stability and also excellent in the water resistance and adhesiveness of the dried film prepared therefrom. CONSTITUTION: This adhesive is obtained by polymerization between (A) a polyisocyanate compound having two or more isocyanate groups, (B) a polyol compound having two or more hydroxyl groups and (C) a functional compound having two or more active hydrogen atoms reactive with the isocyanate group and also having at least one kind of hydrophilic group selected from carbexyl and sulfonyl groups in the presence of (D) an inorganic organosol to form a urethane polymer and then dispersed it in water.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a urethane-based water-based adhesive having excellent dispersion stability and a dry film having excellent water resistance and adhesiveness.

[0002]

2. Description of the Related Art Urethane-based adhesives have been used for many purposes because they have excellent adhesive strength to a wide range of adherends. Particularly, in recent urethane adhesives, the conventional solvent-based adhesives have been actively changed to water-based adhesives because they have no toxicity and no risk of fire and are economical.

Further, an adhesive method using an adhesive containing silica particles added as a filler to a conventional urethane aqueous adhesive has been disclosed for the purpose of improving the adhesive strength of the urethane aqueous adhesive after curing. (Japanese Patent Laid-Open No. 4-20933).

[0004]

However, the adhesive of the above-mentioned publication is obtained by previously mixing the polymerized urethane polymer in water and then mixing the silica-based particles,
The resulting urethane-based water-based adhesive has low dispersion stability, and since silica-based particles are not uniformly filled in the emulsion particles made of the urethane polymer, when used as an adhesive, the film strength is low and sufficient. There is a problem in that good adhesive strength cannot be obtained.

An object of the present invention is to provide a method for producing a urethane-based water-based adhesive which is excellent in dispersion stability and whose dry film has excellent water resistance and adhesiveness.

[0006]

The urethane polymer used in the present invention comprises (A) a polyisocyanate compound having two or more isocyanate groups, (B) a polyol compound having two or more hydroxyl groups, and (C) an isocyanate group. Obtained by polymerizing a functional compound having two or more active hydrogens capable of reacting and having one or more hydrophilic groups selected from a carboxyl group and a sulfonyl group in the presence of (D) an inorganic organosol. .

The above polyisocyanate compound (A) is
Organic polyisocyanates having two or more isocyanate groups in the molecule, such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 2 used in the production of ordinary urethane resins. , 2,4-Trimethylhexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexyl-2,4-diisocyanate, methylcyclohexyl-2,6 -Diisocyanate, xylylene diisocyanate, 1,3-bis (isocyanate) methylcyclohexane, tetramethylxylylene diisocyanate, transcyclohexane-1,4-diisocyanate, lysine diiso Aliphatic diisocyanates such as cyanate, 2,4-toluylene diisocyanate, 2,6
-Toluylene diisocyanate, diphenylmethane-
Aromatic diisocyanates such as 4,4′-diisocyanate, 1,5-naphthene diisocyanate, tolidine diisocyanate, diphenylmethylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, lysine Ester triisocyanate, triphenylmethane triisocyanate,
1,6,11-Undecane triisocyanate, 1,8
-Triisocyanates such as diisocyanate-4,4-isocyanate methyl octane, 1,3,6-hexamethylene triisocyanate, and bicycloheptane triisocyanate. These may be used alone or in combination of two or more.

The above-mentioned polyol compound (B) is a compound having two or more hydroxyl groups in the molecule, and the physical properties such as hardness and adhesiveness of the urethane polymer obtained by selecting it according to the purpose and application are arbitrary. Can be designed as, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, polyhydric alcohols such as glycerin, polyethylene glycol. , Polyether polyol such as polypropylene glycol, adipic acid, sebacic acid, itaconic acid, maleic anhydride, terephthalic acid,
Dicarboxylic acid such as isophthalic acid and ethylene glycol,
Diethylene glycol, triethylene glycol, 1,
Polyester polyols obtained from glycols such as 4-butanediol, 1,6-hexanediol, propylene glycol, butylene glycol, tripropylene glycol, neopentyl glycol, polycaprolactone polyol, polytetramethylene ether glycol, polybutadiene polyol, polycarbonate polyol , Polythioether polyol and the like. These may be used alone or in combination of two or more.

The functional compound (C) has two or more active hydrogens capable of reacting with an isocyanate group and one or more hydrophilic groups selected from a carboxyl group and a sulfonyl group. Examples of the compound having a carboxyl group as the functional group include 2,2-dimethylol lactic acid, 2,2-dimethylol propionic acid and 2,2-
Examples of the compound having a sulfonyl group as a hydrophilic group include dimethylolbutyric acid and 2,2-dimethylolvaleric acid, and 3,4-diaminobutanesulfonic acid,
3,6-diamino-2-toluenesulfonic acid and the like can be mentioned. These may be used alone or in combination of two or more.

When the hydrophilic group such as a carboxyl group or a sulfonyl group in the functional compound (C) is reduced, it becomes difficult to obtain sufficient dispersion stability of the urethane-based aqueous adhesive obtained by the production method of the present invention. If the amount is too large, it becomes difficult to obtain the water resistance of the urethane-based water-based adhesive after drying. Therefore, the ratio of the hydrophilic group per 1 g of the solid content of the urethane polymer used is preferably 0.1 to 2.0 mmol, and further preferably Is 0.1 to 1.0 mmol.

The molecular weight of the urethane polymer used in the present invention is designed by the equivalent ratio of isocyanate groups and active hydrogen, that is, [isocyanate equivalent in (A)] / [active hydrogen equivalent in (B) and (C)]. To be done. When the above equivalence ratio is close to 1.0, the molecular weight of the resulting urethane polymer becomes high, and it becomes difficult to obtain sufficient dispersibility in water, and when it becomes large, the urethane polymer has a low molecular weight, and when the chain is extended thereafter. Low polymer molecular weight,
As it becomes difficult to obtain sufficient adhesive performance as an adhesive,
The above equivalent ratio is preferably 1.1 to 2.0, more preferably 1.3 to 2.0.

The inorganic organosol (D) is a colloidal solution in which inorganic colloidal particles are stably dispersed in an organic solvent, and the inorganic colloidal particles are stably dispersed in the urethane polymer by allowing them to coexist when polymerizing the urethane polymer. It becomes possible.

The inorganic colloidal particles dispersed in the above inorganic organosol (D) include metal oxides such as silica, alumina, antimony pentoxide, titanium oxide and zirconia, aluminum hydroxide, cadmium hydroxide, cobalt hydroxide, Examples thereof include metal hydroxides such as copper hydroxide and iron hydroxide.

As the dispersion solvent for the inorganic organosol (D), those which are inert to isocyanate groups and have high compatibility with water are desirable, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, acetic acid. Examples thereof include ethyl and dimethylacetamide.

As the commercially available inorganic organosol (D), "DMAC-ST" (trade name,
Dispersing solvent; dimethylacetamide), "MIBK-S
Organosilica sol such as "T" (trade name, dispersion solvent; methyl isobutyl ketone), "Sun Colloid ATL-13"
0 (trade name, dispersion solvent: toluene), "Sun colloid AME-130" (trade name, dispersion solvent: methyl ethyl ketone), and the like antimony pentoxide sols, those manufactured by Nissan Chemical Industries, Ltd., and the like.

When the average particle size of the inorganic colloidal particles in the above-mentioned inorganic organosol (D) becomes small, it becomes difficult to produce, and when it becomes large, it tends to settle, and it becomes difficult to obtain sufficient dispersion stability. 0.005-2
It is 0 μm, and more preferably 0.01 to 5 μm.

The urethane polymer used in the present invention is
The polyisocyanate compound (A), the polyol compound (B), the functional compound (C) and the inorganic organosol (D) are mixed in advance and then reacted, that is, in the presence of the inorganic organosol (D), the above (A), It is obtained by polymerizing (B) and (C).

Examples of the method for polymerizing the above mixture include bulk polymerization and solution polymerization, but solution polymerization is preferred from the viewpoint of easy reaction control, and the solvent used in that case is inert to isocyanate groups. And having high compatibility with water are preferable, and examples thereof include acetone, methyl ethyl ketone, tetrahydrofuran, and ethyl acetate.

Further, the lower the polymerization temperature, the lower the polymerization reaction rate, and the higher the polymerization temperature, the more easily gelation occurs during the polymerization reaction.

When the viscosity of the urethane polymer is increased, it becomes difficult to obtain sufficient dispersibility in water or an aqueous solution of the chain extender. Therefore, the viscosity is preferably 10,000 cps or less, more preferably 5,000 cps or less.

The urethane polymer may be diluted with the above-mentioned dispersion solvent for the purpose of adjusting the viscosity to the above or less and obtaining good dispersibility in water or the aqueous solution of the chain extender. At this time, not only a large amount of energy is required in the solvent removal step of the urethane-based water-based adhesive when the amount of the dispersion solvent is large, but the urethane polymer is in a state of being dissolved in the dispersion solvent instead of in water, and the production method of the present invention. Since the viscosity of the urethane-based water-based adhesive obtained in step 1 increases, the urethane polymer solid content is preferably 20% by weight or more, more preferably 4
It is 0% by weight or more, more preferably 60% by weight or more.

The hydrophilic group in the urethane polymer can be ionized with a neutralizing agent to obtain a stable dispersed state in water, and the neutralizing agent may be added for such a purpose. Examples of the neutralizing agent include ammonia, trimethylamine, triethylamine and the like.

By using a chain extender, the above urethane polymer can bond the polymers to each other to extend the polymer chain.

The chain extender is a compound having two or more active hydrogens capable of reacting with the residual isocyanate group in the polymer, and examples thereof include ethylenediamine, 1,2-propanediamine, 1,4-tetramethylenediamine, and 1-tetramethylenediamine. , 6
-Hexamethylenediamine, 1,4-cyclohexanediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3, 3'-dimethyl-4,4 '
Amine compounds such as dicyclohexylmethanediamine, hydrazine, diethylenetriamine and triethylenetetramine, ethylene glycol, propylene glycol,
1,4-butanediol, 1,6-hexanediol,
Examples thereof include polyalkylene glycol represented by polyethylene glycol. Further, chain extension with water as a dispersion medium is also possible. These can be used alone or 2
You may use together more than one kind.

When the volume of water or the aqueous solution of the chain extender with respect to the total amount of the urethane polymer solution added becomes smaller, the urethane polymer is dissolved in the solvent rather than in water, and the viscosity of the resulting urethane-based water-based adhesive is increased. Is increased, and when it is increased, it becomes a dilute urethane-based water-based adhesive with a large amount of water, and the drying time becomes long.
The capacity is 10 times, more preferably 0.2 to 5 times.

When the urethane polymer is added, it is preferable that water or the aqueous solution of the chain extender is in a stirring state. The agitated state means that when the urethane polymer is added to the aqueous solution containing the chain extender (D), it is uniformly dispersed into particles having an average particle size of preferably 30 μm or less, more preferably 10 μm or less, and most preferably 5 μm or less. It refers to the state of stirring as much as possible.

Examples of the mixing and stirrer for realizing the above stirring state include a dissolver, a homogenizer, a static mixer, a line mill, a pressure emulsifier, an ultrasonic emulsifier and the like.

When the urethane-based water-based adhesive obtained by the above-mentioned manufacturing method contains an organic solvent, the urethane-based water-based adhesive containing no organic solvent is obtained by heating or depressurizing.

[0029]

EXAMPLES Next, examples of the present invention will be described. still,
Hereinafter, "part" means "part by weight".

(Example 1) A polypropylene glycol (OH group number: 55, number average molecular weight: 2000, manufactured by NOF Corporation, trade name "UNIOR D-2000") was placed in a reactor equipped with a reflux condenser. 100 parts, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (manufactured by Huls, trade name "VESTANT"
IPDI ") 41 parts, 2,2-dimethylolpropionic acid (manufactured by Trimet Technical Products) 6 parts, organosilica sol (solid content 30% by weight, average particle size 0.0)
1 to 0.015 μm, dispersion solvent methyl isobutyl ketone, manufactured by Nissan Chemical Industries, Ltd., trade name “MIBK-S
T ”) and 75 parts of methyl ethyl ketone are added and stirred until uniform, and then the temperature is raised to carry out boiling point polymerization, and the residual isocyanate group content in the polymer solids is 3.2.
A polymer of 60% by weight was obtained, and after further adding 5 parts of triethylamine, the mixture was stirred for 20 minutes to obtain a urethane polymer solution having a solid content of 60% by weight. Then, 200 parts of the urethane polymer solution obtained above was added to a solution obtained by adding and mixing 5 parts of ethylenediamine to 360 parts of water over 1 minute, and then the solvent was removed by reducing the pressure while stirring at 40 ° C. A urethane-based water-based adhesive having a content of 30% by weight was obtained.

(Example 2) Instead of 50 parts of the organosilica sol "MIBK-ST" and 75 parts of methyl ethyl ketone used in Example 1, an organosilica sol (solid content: 20) was used.
% By weight, average particle diameter 0.01 to 0.015 μm, dispersion solvent dimethylacetamide, manufactured by Nissan Chemical Industries, Ltd., trade name “DMAC-ST”) 75 parts and methyl ethyl ketone 5
The same operation as in Example 1 was carried out except that 0 part was used to obtain a urethane-based aqueous adhesive having a solid content of 30% by weight.

(Example 3) Instead of the organosilica sol "MIBK-ST" used in Example 1, an antimony pentoxide sol (solid content 30% by weight, average particle size 0.03-0.
05 μm, dispersion solvent methyl ethyl ketone, manufactured by Nissan Chemical Industries, Ltd., trade name “Sun Colloid AME-130”)
The same operation as in Example 1 was carried out except that was used to obtain a urethane-based aqueous adhesive having a solid content of 30% by weight.

(Example 4) Instead of the organosilica sol "MIBK-ST" used in Example 1, an antimony pentoxide sol (solid content 30% by weight, average particle size 0.03-0.
A urethane-based water-based adhesive having a solid content of 30% by weight was prepared in the same manner as in Example 1 except that 05 μm, a dispersion solvent of toluene, manufactured by Nissan Chemical Industries, Ltd., trade name “Sun Colloid ATL-130”) was used. I got an agent.

Comparative Example 1 The same operation as in Example 1 was carried out except that 50 parts of the organosilica sol "MIBK-ST" used in Example 1 was not added and methyl ethyl ketone was changed from 75 parts to 98 parts. A urethane-based water-based adhesive having a solid content of 30% by weight was obtained.

(Comparative Example 2) To 200 parts of a urethane-based aqueous adhesive having a solid content of 30% by weight obtained in Comparative Example 1, 20 parts of organosilica sol "MIBK-ST" was added, followed by stirring to obtain 30% by weight. A urethane-based mixed water-based adhesive of was obtained.

(Comparative Example 3) To 200 parts of the urethane-based aqueous adhesive having a solid content of 30% by weight obtained in Comparative Example 1, 30 parts by weight of organosilica sol "DMAC-ST" was added, followed by stirring to obtain 30% by weight. A urethane-based mixed water-based adhesive of was obtained.

(Comparative Example 4) To 200 parts of a urethane-based aqueous adhesive having a solid content of 30% by weight obtained in Comparative Example 1, 20 parts of antimony pentoxide sol "Sun colloid AME-130") was added and stirred. As a result, a 30 wt% urethane-based mixed water-based adhesive was obtained.

Comparative Example 5 To 200 parts of the urethane-based aqueous adhesive having a solid content of 30% by weight obtained in Comparative Example 1, 20 parts of antimony pentoxide sol "Sun colloid ATL-130") was added, and then stirred. As a result, a 30 wt% urethane-based mixed water-based adhesive was obtained.

Evaluation items and evaluation methods are shown below. (Dispersion stability test) Examples 1 to 4 and Comparative Examples 1 to 5 above
Tables 1 and 2 show the results of visually confirming the presence or absence of sediment for the urethane-based water-based adhesive and the urethane-based mixed water-based adhesive obtained in step 3 by leaving them in a closed glass container at 23 ° C. for 2 months. It was (Adhesion test) The urethane-based water-based adhesives and urethane-based water-based adhesives obtained in Examples 1 to 4 and Comparative Examples 1 to 5 were each subjected to a JIS L-3102 standard canvas (normal cotton No. 9, width 25 mm). , Length 125mm), then 80 ℃
An adhesive-impregnated canvas having a solid content coating amount of 2 mg / cm ² was obtained by drying in a blast drying oven for 3 minutes. Similarly, stainless steel plate (SUS304, width 25 m
m, length 125 mm, thickness 2 mm) and then dried for 3 minutes in a blast drying oven at 80 ° C. to obtain an adhesive-coated stainless steel sheet having a solid content conversion amount of 0.8 mg / cm ² . Then, the coated surface of the adhesive-impregnated canvas and the coated surfaces of the adhesive-coated stainless steel plate are brought together, and the press temperature is set to 80.
A test piece was obtained by pressing at 5 ° C. and a pressing pressure of 10 kg / cm ² for 5 minutes and bonding. The obtained test piece is 2
90 at a pulling speed of 50 mm / min under 3 ° C conditions
The results of the peel test are shown in Tables 1 and 2. The unit is kg / 25 mm. (Water resistance adhesion test) A test piece similar to the above adhesion test was prepared, immersed in 40 ° C warm water for 3 days, wiped off moisture, and peeled at 90 ° under a condition of 23 ° C and a pulling speed of 50 mm / min. The results of the tests are shown in Tables 1 and 2.
The unit is kg / 25 mm.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

The urethane-based water-based adhesive obtained by the production method of the present invention has the inorganic organosol added in the polymerization stage of the polymer used as a raw material, so that the inorganic organosol is uniformly mixed and dispersed. Therefore, the dispersion stability is excellent, the dry film strength is high, and a sufficient cohesive force is maintained. Moreover, since the obtained urethane-based water-based adhesive does not contain an emulsifier such as a surfactant, the water resistance of the dried film is excellent. Therefore, for example, when applied to paints and adhesives, uniform coating is possible, it is difficult to form agglomerates and excellent in storage stability for a long time, and swelling due to agglomerates, adhesion failure after use, etc. It is suitable because there is no trouble and there is no deterioration of the film after drying due to atmospheric humidity.

Claims (1)

[Claims] 1. A polyisocyanate compound having two or more (A) isocyanate groups, (B) a polyol compound having two or more hydroxyl groups, and (C) two or more active hydrogens capable of reacting with an isocyanate group, and Polymerizing a functional compound having one or more hydrophilic groups selected from a carboxyl group and a sulfonyl group in the presence of (D) an inorganic organosol to obtain a urethane polymer, and then dispersing the urethane polymer in water. A method for producing a urethane-based water-based adhesive characterized by the above.