JPH1180537A - Solventless one-pack moisture-curing polyisocyanate composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solventless one-pack moisture-curing polyisocyanate composition having excellent weather resistance and long pot-life and proceeding the curing reaction at a high reaction rate. SOLUTION: This composition having a nonvolatile component content of >=98 wt.% and essentially free from organic solvent can be produced by reacting (A) a polyether polyol having a number-average molecular weight of 300-8,000 and preferably a monoalcohol having a number-average molecular weight of 60-600 with (B) excess hexamethylene diisocyanate and/or a polyisocyanate containing the diisocyanate as a basic skeleton and mixing the resultant polyisocyanate prepolymer with 0.005-2 wt.% (based on the polyisocyanate prepolymer) of a moisture cure-accelerating catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-part moisture-curable polyisocyanate composition which is cured by reacting with moisture (steam) in the air. It is useful as a paint, a sealing material, a waterproofing material and an adhesive. The present invention relates to a one-component moisture-curable polyisocyanate composition for a solvent.

[0002]

2. Description of the Related Art Conventionally, a one-pack moisture-curable polyisocyanate composition using an aromatic diisocyanate as a raw material has been
It is widely known that they have excellent water resistance, chemical resistance and the like. However, one-part moisture-cured polyisocyanates using aromatic diisocyanates as raw materials are characterized by yellowing by light, and their use in applications requiring weather resistance has been limited. Furthermore, one-part moisture-cured polyisocyanates using aromatic diisocyanates as raw materials have high viscosity. In order to improve handling and release carbon dioxide generated when the isocyanate group reacts with water from the coating film, it is necessary to reduce the viscosity.For this reason, it is necessary to dilute with a large amount of volatile organic solvent. Did not.

However, in recent years, guidelines regarding volatile organic solvents have become strict, and regulations have already been implemented in the United States, Germany, and the like. Accordingly, there is a demand for a one-part moisture-curable polyisocyanate composition to reduce volatile organic solvents. On the other hand, polyisocyanates using aliphatic diisocyanates as raw materials have a slower reaction with water than aromatic polyisocyanates, so when used as a one-part moisture-curable polyisocyanate, it takes a long time to cure the coating film. And the practicality was extremely low.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a one-part moisture-curable polyisocyanate composition having excellent weather resistance and curing rate and free of volatile organic solvents.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a moisture curing accelerating catalyst is mixed with a polyisocyanate prepolymer having hexamethylene diisocyanate having a specific structure as a basic skeleton. The present inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

That is, the present invention is as follows. 1) a polyisocyanate prepolymer obtained by reacting (A) a polyether polyol having a number average molecular weight of 300 to 8000 with (B) an excess amount of hexamethylene diisocyanate and / or a polyisocyanate having the same as a basic skeleton; A one-component moisture-curable polyisocyanate composition comprising 0.005 to 2% by weight of a moisture-curing promoting catalyst mixed with a prepolymer, and having a nonvolatile component content of 98% by weight or more.

2) (A) Number average molecular weight 300 to 8000
Polyether polyol and (C) a number average molecular weight of 60 to
A polyisocyanate prepolymer obtained by reacting 600 monohydric alcohols with (B) an excess amount of hexamethylene diisocyanate and / or a polyisocyanate having the same as a basic skeleton; and 0.005 to 2% by weight based on the polyisocyanate prepolymer. % Of a one-component moisture-curable polyisocyanate composition, wherein the one-component moisture-curing promotion catalyst is mixed and the nonvolatile component is 98% by weight or more.

Hereinafter, the present invention will be described in detail. In the present invention, by using a polyether polyol,
It facilitates the penetration of water vapor into the inside of the coating film, and makes it easier for carbon dioxide generated when the isocyanate group reacts with water to escape from the coating film. This is due to the effect of the structure that easily permeates water vapor and carbon dioxide of polyether polyol,
This is because the viscosity of the polyisocyanate prepolymer obtained by reacting the polyether polyol can be kept low.

The polyether polyol (A) used in the present invention is, for example, polyethylene glycol or polypropylene obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to a polyhydric alcohol such as ethylene glycol, propylene glycol or glycerin. Examples include polytetramethylene ether glycol obtained by ring-opening polymerization of glycol or tetrahydrofuran.

Commercially available polyols include PEG as polyethylene glycols.
400, PEG1000, PEG2000 (all manufactured by Hodogaya Chemical Co., Ltd.), as polypropylene glycols, PPG1000, PPG4000 (all manufactured by Hodogaya Chemical Co., Ltd.), Exenol 820, Exenol 840 (all manufactured by Asahi Glass Industry Co., Ltd., trifunctional PTG1000, PTG2000 as polypropylene glycol) and polytetramethylene glycols
(Both manufactured by Hodogaya Chemical Co., Ltd.).

The number average molecular weight of the polyether polyol used in the present invention is 300 to 8000, preferably 4 to 8,000.
It is from 00 to 8000, more preferably from 400 to 7000. If the number average molecular weight is less than 300, the crosslinking density becomes too large, impeding the penetration of water vapor into the inside of the coating film and the escape of carbon dioxide outside the film, so that the curing reaction inside the coating film becomes slow and It is not suitable because carbon dioxide bubbles are easily generated inside the membrane. Also, if it exceeds 8000,
This is not suitable because the coating density is too low to make the coating film brittle.

By defining the type and molecular weight of the polyol, the crosslink density of the coating film becomes appropriate, and a fast curing reaction and a clear and tough coating film can be achieved. That is, it becomes easy for water vapor to penetrate into the inside of the coating film, the curing reaction proceeds quickly, and carbon dioxide generated at the time of the crosslinking reaction easily escapes outside the film. Further, the strength of the coating film can be adjusted by appropriately selecting the molecular weight of the polyol. That is, when a low molecular weight polyol having a molecular weight of 1000 or less is used, a hard and tough coating film can be obtained, and when a high molecular weight polyol having a molecular weight of 4000 or more is used, a soft and flexible coating film is formed. Obtainable. Therefore, the mechanical properties of the coating film can be controlled by appropriately selecting and blending these polyols.

In the present invention, the monoalcohol (C) can be used in combination with the above (A). Monoalcohol reduces the viscosity of the polyisocyanate prepolymer, facilitates the penetration of water vapor into the interior of the coating film, and has the effect of accelerating the curing reaction and the carbon dioxide generated when the isocyanate group reacts with water. It has the effect of making it easier to escape from the film.

The number average molecular weight of the monoalcohol is 60 to 6
00, preferably 60 to 500, more preferably 60 to 400. When the molecular weight is less than 60, the effect of using a monoalcohol, that is, the effect of lowering the viscosity, permeating water vapor into the inside of the coating film, or making carbon dioxide easily escape from the coating film cannot be exhibited, which is not preferable. Also, 6
If it exceeds 00, the viscosity of the polyisocyanate prepolymer is rather increased, which is not preferable.

Examples of such a monoalcohol include 1-butanol, 1-octanol, 1-tridecanol, ceryl alcohol, 2-ethyl-1-hexanol, 5-ethyl-2-nonanol and the like. In the present invention, (B) an excess amount of hexamethylene diisocyanate and / or a polyisocyanate having the same as a basic skeleton is used.

Hexamethylene diisocyanate is characterized in that it is easily available industrially, has excellent weather resistance, has a relatively fast curing reaction rate, and has a low viscosity of the polyisocyanate prepolymer. The polyisocyanate having hexamethylene diisocyanate as a basic skeleton has a structure such as buret, isocyanurate, urethane, uretdione, allophanate or the like in a molecule.

The "excess amount" of hexamethylene diisocyanate and / or polyisocyanate having the same as a basic skeleton in the present invention means that the equivalent ratio of the isocyanate group to the hydroxyl group of the above polyol or the like is 1 or more. I have. Accordingly, when a polyol or the like is reacted with hexamethylene diisocyanate and / or a polyisocyanate having the same as a basic skeleton, an isocyanate group remains at a molecular terminal.

The reaction referred to in the present invention means the above-mentioned polyether polyol (A), monoalcohol (C) used in combination with (A), hexamethylene diisocyanate and / or polyisocyanate (B) ) Is urethanized or allophanated. The moisture hardening accelerating catalyst used in the present invention is a catalyst that promotes a reaction for generating a urea group from two isocyanate groups and one water molecule. As such a catalyst, for example, tin compounds such as dimethyltin dichloride, dibutyltin dichloride, dioctyltin dichloride, monobutyltin trichloride, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin malate, dibutyltin oxide, dioctyltin oxide, and the like, tributylamine, Tertiary amines such as tetramethylethylenediamine, tetramethylpropanediamine, tetramethylhexanediamine, methylmorpholine, dimethylpiperazine, and trimethylaminomethylethanolamine.

The mixing amount of the moisture curing accelerating catalyst used in the present invention is 0.0
It is 0.5 to 2% by weight, preferably 0.02 to 2% by weight, more preferably 0.04 to 1.5% by weight.
If the amount is less than 0.005% by weight, the effect of promoting moisture hardening is not sufficient, so that it is not suitable. If it exceeds 2% by weight, the pot life is shortened and the storage stability is lowered, so that it is not suitable. Here, the pot life is the pot life of a paint or a sealing material when left in the air.

In the present invention, the one-component moisture-curable polyisocyanate composition has a nonvolatile content of 98% by weight or more. The content of 98% by weight or more means that it contains substantially no volatile components. If the content is less than 98% by weight, the one-component moisture-curable polyisocyanate composition contains a volatile component, and the volatile component is released into the air at the time of forming a coating film.

The viscosity of the one-pack moisture-curable polyisocyanate composition of the present invention is from 400 to 10,000 mPa.s. s (2
5 ° C) is appropriate. 400 mPs. If it is less than s, components not involved in crosslinking increase, and the coating film tends to be brittle. 10,000 mPa. If it exceeds s, carbon dioxide generated when the isocyanate group reacts with water may remain in the coating film.

The one-part moisture-curable polyisocyanate composition of the present invention has an isocyanate group content of 2 to 20% by weight.
Is appropriate. If it is less than 2% by weight, the crosslinking density tends to be low and the coating tends to be brittle. If it exceeds 20% by weight, the crosslinking density becomes large, and the penetration of water vapor into the coating and the escape of carbon dioxide to the outside of the film. Insufficiency of dispersion causes the curing reaction inside the coating film to slow down, and also facilitates the generation of carbon dioxide bubbles inside the coating film. The desired isocyanate group content can be attained by adjusting the amounts of hexamethylene diisocyanate and / or polyisocyanate having the same as its basic skeleton and polyether polyol or monoalcohol.

In the polyisocyanate composition of the present invention, pigments, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, surfactants, etc., in the technical field according to the purpose and application. Various additives used in the above can also be mixed. Since the polyisocyanate composition of the present invention uses hexamethylene diisocyanate as a raw material as described above, compared with a polyisocyanate composition using an aromatic diisocyanate as a raw material, it is significantly excellent in weather resistance and yellowing of a coating film. .

Further, it has a feature that the pot life is longer than that of a polyisocyanate composition using an aromatic diisocyanate as a raw material. Further, the polyisocyanate composition of the present invention also has a feature that the curing reaction proceeds quickly to the inside of the coating film. This has been achieved because the polyisocyanate composition has a structure that allows water vapor to easily penetrate, and further contains a moisture-curing accelerating catalyst.

Further, since the polyisocyanate composition of the present invention does not substantially contain a volatile component, the polyisocyanate composition also has a feature that the volatile component is not released into the air when a coating film is formed.
One-part moisture-curable polyisocyanate composition of the present invention,
It has features of excellent weather resistance, long pot life, and rapid progress of the curing reaction. Also, metals, especially aluminum and steel plates, glass, plastics, fibers,
Excellent adhesion to substrates such as wood, paints, sealing materials, waterproofing materials, adhesives, especially metal and metal, glass and metal, metal and plastic, glass and glass, plastic and glass, wood And glass, metal and fiber, glass and fiber, plastic and fiber adhesives, and more specifically, mirror backing adhesives, inks and coatings, especially paper, cloth and wood coatings, It can be used in a wide range of fields such as casting materials, elastomers and plastic raw materials.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be further described with reference to examples. The measurement method used in the present invention is shown below. [Isocyanate group content (hereinafter referred to as NCO content)] The isocyanate groups of the polyisocyanate composition were neutralized with an excess of amine, and then determined by back titration with hydrochloric acid.

[Viscosity] The viscosity was measured at 25 ° C. and 60 rpm using a digital viscometer (Tokyo Keiki Co., Ltd .; model DVM-B). [Non-volatile content] About 0.1 g in a 5.5 cm diameter aluminum dish
Was precisely weighed and heated at 105 ° C. for 3 hours, and then the heated polyisocyanate composition was precisely weighed and determined by the following formula.

Nonvolatile content = (weight of polyisocyanate composition after heating) / (weight of polyisocyanate before heating) ×
100% [number average molecular weight] It was measured according to the following method using gel permeation chromatography (GPC).

When the number average molecular weight is less than 2,000, columns: Tosoh Corporation G1000HXL, G2000HX
L, G3000HXL, carrier: THF, detection method: parallax refractometer, data processor: Tosoh CP-8
000. When the number average molecular weight is 2000 or more, column: Tosoh Corporation G2000HXL, G400
0HXL, G5000HXL, carrier: THF, inspection method: parallax refractometer, data processor: Tosoh Corporation Ch
It was measured with a romantocoder21.

[Tack-free of coating film] The coating film surface was lightly touched with a finger and determined by the time when the sticky feeling disappeared. [Reaction rate of isocyanate group of coating film] It was determined by measuring the reduction rate of isocyanate group using FT-IR (JASCO Corporation; FT / IR-700).

[Yellow value of coating film] Color difference gloss type (Suga Test Instruments Co., Ltd .; SM Color Computer Model SM-5)
Then, the Y value of the coating film was measured and determined.

[0032]

Example 1 A four-necked flask equipped with a stirrer, a thermometer, and a cooling tube was charged with hexamethylene diisocyanate (hereinafter, referred to as a "height").
HDI) and 500 g of 2-ethylhexanol 5
0 g and 47 g of Exenol 840 (manufactured by Asahi Glass Co., Ltd., polypropylene glycol, number average molecular weight 6500) were charged, and a urethanization reaction was performed at 90 ° C. for 2 hours with stirring. At 90 ° C., 0.02 g of tetramethylammonium capryate was added as an isocyanuration catalyst. 4
After a lapse of time, when the increase in the refractive index of the reaction solution became 0.015, 0.1 g of phosphoric acid was added to stop the reaction.

Using a falling-film thin-film distillation apparatus, the first 0.1.
3 Tor. (150 ° C.), 0.2 Tor. To remove unreacted HDI. The obtained polyisocyanate prepolymer was 283 g, had a viscosity of 1,000 mPa · s,
The CO content was 14.6% and the nonvolatile content was 99.2% by weight. To the obtained polyisocyanate prepolymer, dibutyltin dilaurate was mixed at 0.1% by weight based on the polyisocyanate prepolymer to obtain a polyisocyanate composition.

The polyisocyanate composition obtained above was applied on a glass plate in a thickness of 100 μm and a thickness of 500 μm, and left at 20 ° C. and 65% RH. Thickness 500
No air bubbles or the like were observed in the μm coating film. Thickness 1
The tack free of the 00 μm coating was 12 hours. The isocyanate group reaction rate of the coating film having a thickness of 100 μm was 80% on the first day and 100% on the seventh day.

Further, after the polyisocyanate composition having a thickness of 100 μm applied on a white plate was allowed to stand at 20 ° C. and 65% RH for 1 week, accelerated weathering test was conducted with a sunshine weather meter. It was 1.5 at 1000 hours.

[0036]

Embodiment 2 Using the same apparatus as in Embodiment 1, HDI was
00g, 20 g of PPG1000 (manufactured by Hodogaya Chemical Co., number average molecular weight 1000) and 1.9 g of water were added, and the mixture was stirred.
The biuret reaction was performed at 0 ° C. for 1 hour. Then, unreacted HDI was removed in the same manner as in Example 1.

The polyisocyanate prepolymer has a viscosity of 2400 mPa.s. s, the NCO content was 19.0%, and the nonvolatile content was 98.8% by weight. Dibutyltin dilaurate was mixed with the obtained polyisocyanate prepolymer in an amount of 0.3% by weight based on the polyisocyanate prepolymer to obtain a polyisocyanate composition.

The polyisocyanate composition obtained above was applied on a glass plate in a thickness of 100 μm and a thickness of 500 μm, and left at 20 ° C. and 65% RH. Thickness 500
Only a few bubbles were observed in the μm coating. The tack-free of the coating film having a thickness of 100 μm was 8 hours. When the isocyanate group reaction rate of the coating film was measured,
%, And 100% on the seventh day.

After the polyisocyanate composition having a thickness of 100 μm applied on a white plate was allowed to stand at 20 ° C. and 65% RH for one week, an accelerated weathering test was conducted with a sunshine weather meter. It was 1.8 in 1000 hours.

[0040]

Example 3 Using the same apparatus as in Example 1, HDI was
00g and 4-ethylhexanol 41.3g,
The urethanization reaction was performed at 90 ° C. for 2 hours with stirring. 90 ° C
Then, 0.02 g of tetramethylammonium capryate was added as an isocyanuration catalyst. Four hours later, when the increase in the refractive index of the reaction solution became 0.014, 0.1 g of phosphoric acid was added to stop the reaction.

Then, as in Example 1, unreacted H
DI was removed. Using 216.5 g of the obtained polyisocyanate prepolymer and 64.7 g of exenol 840, the mixture was reacted at 120 ° C. for 5 hours to obtain a polyisocyanate prepolymer. This polyisocyanate prepolymer has a viscosity of 1500 mPa · s and an NCO content of 13.
5% and the non-volatile content was 99.1% by weight.

The obtained polyisocyanate prepolymer was mixed with 0.6% by weight of dibutyltin dilaurate based on the polyisocyanate prepolymer to obtain a polyisocyanate composition. The polyisocyanate composition obtained above was coated on a glass plate to a thickness of 100 μm, and
It was applied in a thickness of μm and left at 20 ° C. and 65% RH. No bubbles or the like were observed in the 500 μm thick coating film. The tack-free state of the coating film having a thickness of 100 μm was 7 hours. When the isocyanate group reaction rate of the coating film was measured,
It was 70% on day 7 and 100% on day 7.

After the polyisocyanate composition having a thickness of 100 μm applied on a white plate was allowed to stand at 20 ° C. and 65% RH for one week, an accelerated weathering test was carried out with a sunshine weather meter. It was 1.4 at 1000 hours.

[0044]

Comparative Example 1 Using the same device as in Example 1, HDI was
At 60 ° C., 0.02 g of tetramethylammonium capryate was used as an isocyanuration catalyst.
added. Four hours later, when the increase in the refractive index of the reaction solution became 0.010, 0.1 g of phosphoric acid was added to stop the reaction.

Then, purification was carried out in the same manner as in Example 1. The obtained polyisocyanate prepolymer is 205
g, transparent liquid, viscosity 1500 mPa · s, N
The CO content was 23.0%, and the nonvolatile content was 99.3%.
Dibutyltin dilaurate was mixed with the obtained polyisocyanate prepolymer in an amount of 0.3% by weight based on the polyisocyanate prepolymer to obtain a polyisocyanate composition.

The polyisocyanate composition obtained above was applied on a glass plate to a thickness of 100 μm and a thickness of 500 μm, and left at 20 ° C. and 65% RH. Thickness 500
Many bubbles were observed in the μm coating. Thickness 100μ
m was 7 hours tack-free. The isocyanate group reaction rate of the coating film was 50% on the first day and 100% on the seventh day.

Further, after the polyisocyanate composition applied to a thickness of 100 μm on a white plate was allowed to stand at 20 ° C. and 65% RH for one week, an accelerated weather resistance test was conducted with a sunshine weather meter. It was 1.2 at 1000 hours.

[0048]

Comparative Example 2 Using the same apparatus as in Example 1, 500 g of tolylene diisocyanate and 50 g of 2-ethylhexanol were used.
g and 47 g of Exenol 840 (manufactured by Asahi Glass Co., Ltd., polypropylene glycol, number average molecular weight 6500) were charged, and a urethanization reaction was performed at 90 ° C. for 2 hours with stirring.
At 90 ° C., 0.02 g of tetramethylammonium capryate was added as an isocyanuration catalyst. After 4 hours, when the increase in the refractive index of the reaction solution becomes 0.015,
The reaction was stopped by adding 0.1 g of phosphoric acid.

The obtained polyisocyanate prepolymer weighed 303 g and was a transparent liquid having a viscosity of 3800 mPa.
-The s and NCO content was 12.2%. To the obtained polyisocyanate prepolymer, dibutyltin dilaurate was added in an amount of 0.3 to the polyisocyanate prepolymer.
% By weight to obtain a polyisocyanate composition.

The polyisocyanate composition obtained above was applied on a glass plate in a thickness of 100 μm and a thickness of 500 μm, and left at 20 ° C. and 65% RH. 500μ thickness
A number of bubbles were observed in the coating film of m. The tack free of the coating was 8 hours. The isocyanate group reaction rate of the coating film was 70% on the first day and 100% on the seventh day.

After the polyisocyanate composition applied on a white plate having a thickness of 100 μm was allowed to stand at 20 ° C. and 65% RH for one week, an accelerated weathering test was conducted with a sunshine weather meter. 24 hours.

[0052]

The one-part moisture-curable polyisocyanate composition of the present invention has excellent weather resistance, a long pot life, quick curing reaction, and excellent adhesion to a substrate. It has an excellent feature that it does not contain volatile organic solvents. Therefore, it is extremely useful in a wide range of fields such as paints, sealing materials, waterproof materials, adhesives, inks, coating materials, casting materials, elastomers, and plastic raw materials.

Claims (2)

[Claims] 1. A polyisocyanate prepolymer obtained by reacting (A) a polyether polyol having a number average molecular weight of 300 to 8000 with (B) an excessive amount of hexamethylene diisocyanate and / or a polyisocyanate having the same as a basic skeleton. A one-pack moisture-curable polyisocyanate composition comprising a mixture of 0.005 to 2% by weight of a moisture-curing promoting catalyst with respect to the polyisocyanate prepolymer, wherein the nonvolatile component is 98% by weight or more. 2. A polyether polyol having a number average molecular weight of 300 to 8000 (A) and a number average molecular weight of 60 to 6 (C).
And a polyisocyanate prepolymer obtained by reacting a monoalcohol of No. 00 with (B) an excess amount of hexamethylene diisocyanate and / or a polyisocyanate having the same as a basic skeleton, and 0.005 to 2 wt. % Of a one-component moisture-curable polyisocyanate composition, wherein the one-component moisture-curing promotion catalyst is mixed and the nonvolatile component is 98% by weight or more.