JPH11240936A - Polyisocyanate oligomer and polyurethane paint using the polyisocyanate oligomer - Google Patents

Abstract

(57) [Problem] To provide a polyisocyanate oligomer having excellent weather resistance and also having improved drying properties and adhesion of a coating film. A number average molecular weight of 300 to 20 derived from 1,4-bis (isocyanatomethyl) cyclohexane is provided.
A polyisocyanate oligomer in the range of 000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyisocyanate oligomer having a terminal isocyanate group for use in polyurethane paints, adhesives, binders and the like.

[0002]

BACKGROUND OF THE INVENTION Organic isocyanate compounds are often used as polyisocyanate oligomers derived from diisocyanate monomers. As the polyisocyanate oligomer, polyurethane-type polyisocyanate oligomer, isocyanurate-type polyisocyanate oligomer, uretdione-type polyisocyanate oligomer, biuret-type polyisocyanate oligomer, allophanate-type polyisocyanate oligomer,
Polyurea-type polyisocyanate oligomers and the like are well known. Polyisocyanate oligomers derived from these diisocyanate compounds are widely used as raw materials for curing agents for polyurethane coatings, adhesives, foams and the like. Particularly for polyurethane coating applications, various polyisocyanate oligomers having better performance have been developed.

[0003] Among polyisocyanate oligomers derived from diisocyanate compounds, polyisocyanate oligomers derived from so-called aromatic isocyanates, in which isocyanate groups such as toluene diisocyanate and diphenylmethane diisocyanate are directly bonded to aromatic rings, have fast drying properties and chemical resistance. But has the disadvantage that the weather resistance is extremely poor.

On the other hand, when a polyisocyanate oligomer derived from an aliphatic isocyanate such as hexamethylene diisocyanate (hereinafter, referred to as HDI) or isophorone diisocyanate (hereinafter, referred to as IPDI) is used, weather resistance is considerably improved, but disadvantages are also encountered. is there. For example, a polyisocyanate oligomer derived from HDI has a drawback that the coating film has flexibility but a long drying time. In addition, polyisocyanate oligomers derived from IPDI have a short drying time, but have the drawback that the coating film is inflexible and has poor adhesion to the substrate. Among polyisocyanate oligomers derived from aliphatic isocyanates, polyisocyanate oligomers derived from bis (isocyanatomethyl) cyclohexane are known to have excellent weather resistance.

Japanese Patent Publication No. 55-29083 discloses a method for producing a prepolymer for urethane coatings by reacting ω · ω′-diisocyanate dimethylcyclohexane with a low molecular weight polyol to extract and remove unreacted ω · ω′-diisocyanate dimethylcyclohexane. It is stated that
In particular, the isocyanate oligomer having a polyurethane bond derived from ω · ω′-diisocyanate-1,3-dimethylcyclohexane, that is, 1,3-bis (isocyanatomethyl) cyclohexane, gives a prepolymer having particularly excellent solubility in a solvent. Is described.

[0006]

As described above, polyisocyanate oligomers derived from aromatic isocyanates are excellent in quick-drying property and chemical resistance, but are inferior in weather resistance. On the other hand, when a polyisocyanate oligomer derived from an aliphatic isocyanate is used, the weather resistance is considerably improved. However, a polyisocyanate oligomer derived from HDI has a long drying time, and a polyisocyanate oligomer derived from IPDI is used in a coating film. There is a drawback that there is no flexibility and the adhesion to a substrate is poor. SUMMARY OF THE INVENTION An object of the present invention is to provide a polyisocyanate oligomer having excellent weather resistance and improved drying and adhesion of a coating film.

[0007]

The present inventors have studied polyisocyanate oligomers derived from various aliphatic isocyanates in order to solve the above-mentioned problems.
1,4-bis (isocyanatomethyl) which is an isomer of 1,3-bis (isocyanatomethyl) cyclohexane
Polyisocyanate oligomer derived from cyclohexane, and by using a polyisocyanate oligomer having a number average molecular weight in the range of 300 to 20,000, while having excellent weather resistance, short drying time,
Moreover, they have found that a coating film having good adhesion to a substrate can be obtained, and have reached the present invention. That is, the present invention relates to 1,4
Polyisocyanate oligomer derived from -bis (isocyanatomethyl) cyclohexane in the range of 300 to 20,000 and number average molecular weight derived from 1,4-bis (isocyanatomethyl) cyclohexane in the range of 300 to 20,000 A polyurethane paint comprising a polyisocyanate oligomer and a polyol.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1,4-Bis (isocyanatomethyl) cyclohexane used in the present invention can be synthesized from 1,4-bis (aminomethyl) cyclohexane. 1,4-Bis (isocyanatomethyl) cyclohexane has cis and trans geometric isomers, and in the present invention, any one of them can be used alone, or a mixture of any ratio can be used.

The polyisocyanate oligomer of the present invention includes a polyurethane-type polyisocyanate oligomer, an isocyanurate-type polyisocyanate oligomer, a uretdione-type polyisocyanate oligomer derived from 1,4-bis (isocyanatomethyl) cyclohexane by a known method. Biuret-type polyisocyanate oligomer, allophanate-type polyisocyanate oligomer, and polyurea-type polyisocyanate oligomer are used.

[0010] Among the above polyisocyanate oligomers, polyurethane type polyisocyanate oligomers include
It is obtained by reacting 1,4-bis (isocyanatomethyl) cyclohexane with polyfunctional alcohols. Isocyanurate-type polyisocyanate oligomer is disclosed in
As described in JP-A-3-27347 and JP-B-6-25327, it can be obtained using a known trimerization catalyst such as a tetraalkylammonium salt or an alkali metal salt of an organic acid. The uretdione-type polyisocyanate oligomer can be obtained by using a trialkylphosphine as a catalyst as described in JP-A-6-172735. The biuret-type polyisocyanate oligomer is obtained by reacting a biuret agent such as water. The allophanate-type polyisocyanate oligomer is obtained by reacting with a compound having a urethane group. The polyurea-type polyisocyanate oligomer is obtained by reacting with a compound having an amino group. As the polyisocyanate oligomer of the present invention, a polyisocyanate oligomer obtained by combining two or more of the above methods can be used.

The polyisocyanate oligomer in the present invention has a normal molecular weight distribution, and unreacted 1,
4-bis (isocyanatomethyl) cyclohexane may be contained, but unreacted 1,4
The smaller the content of -bis (isocyanatomethyl) cyclohexane, the better. Unreacted 1,4-bis (isocyanatomethyl) cyclohexane may be removed from the polyisocyanate oligomer in the present invention by an operation such as distillation or extraction. The number average molecular weight of the polyisocyanate oligomer according to the present invention is from 300 to 20,000. When the number average molecular weight is 300 or less, the molecular weight of 1,4-bis (isocyanatomethyl) cyclohexane is 1
Since it is 94, it contains a large amount of unreacted 1,4-bis (isocyanatomethyl) cyclohexane, which is not preferable in terms of safety and the like. The number average molecular weight is 2000
If it exceeds 0, its fluidity becomes poor, the viscosity becomes high, and a large amount of volatile solvent to be used is required.

The polyol used for obtaining the polyurethane coating of the present invention includes acrylic polyols, fluorine-containing polyols, hydrocarbon polyols, polyether polyols, polyester polyols,
Epoxy polyols and polycarbonate polyols are exemplified. Among these polyols, acrylic polyols and fluorinated polyols are preferable in terms of weather resistance, drying properties, and adhesion to a substrate.

[0013]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited by these examples.

Example 1 500.6 g of 1,4-bis (isocyanatomethyl) cyclohexane (hereinafter referred to as 1,4-BIC) was placed in a 1-liter flask equipped with a reflux condenser, a stirring rod, a thermocouple and a dropping funnel. (2.58 mol), and heated and maintained at 100 ° C. under a nitrogen stream. 43.2 g (0.32 mol) of trimethylolpropane (hereinafter referred to as TMP)
Was added dropwise over 2 hours, followed by a reaction for 3 hours while maintaining the temperature at 100 ° C. After completion of the reaction, unreacted 1,4-BIC was distilled off at a degree of vacuum of 1 torr to obtain 201.2 g of a polyisocyanate oligomer. The content of 1,4-BIC was 0.1% by weight. The number average molecular weight of this polyisocyanate oligomer was 1200. Ethyl acetate was added to the polyisocyanate oligomer and mixed uniformly to obtain a polyisocyanate oligomer having a solid content of 75% by weight. The viscosity at that time is 2500 mPa at 25 ° C.
In s, the NCO equivalent was 353.

Example 2 1,4-BIC500.2 was placed in a 1-liter flask equipped with a reflux condenser, a stirring rod, a thermocouple and a dropping funnel.
g (2.58 mol), and heated and maintained at 60 ° C. under a nitrogen stream. 1.65 Tetramethylammonium 2-ethylhexanoate (35% ethyl cellosolve solution)
g was added dropwise. The reaction solution was reacted at 60 to 70 ° C. for 1 hour, and then 0.65 g of phosphoric acid was added to terminate the reaction. After completion of the reaction, unreacted 1,4-B
The IC was distilled off, and the polyisocyanate oligomer 114.
3 g were obtained. The content of 1,4-BIC was 0.4% by weight. The number average molecular weight of this polyisocyanate oligomer was 752. Butyl acetate is added to this polyisocyanate oligomer and mixed uniformly to obtain a solid content of 70%.
% By weight of the polyisocyanate oligomer was obtained. Its viscosity is 710 mPa · s at 25 ° C. and its NCO equivalent is 305
Met.

Comparative Example 1 1737.8 g of 1,3-bis (isocyanatomethyl) cyclohexane (hereinafter referred to as 1,3-BIC) was placed in a 1-liter flask equipped with a reflux condenser, a stir bar, a thermocouple and a dropping funnel. (8.95 mol) and heated and maintained at 100 ° C. under a nitrogen stream. 136.6 g (1.12 mol) of trimethylolpropane (TMP) was added dropwise over 2 hours, and the mixture was reacted for 3 hours while maintaining the temperature at 100 ° C. After completion of the reaction, unreacted 1,3-BIC was distilled off at a degree of vacuum of 1 torr to obtain 380.9 g of a polyisocyanate oligomer. The content of 1,3-BIC is 0.5
% By weight. The number average molecular weight of this polyisocyanate oligomer was 1,100. Ethyl acetate was added to the polyisocyanate oligomer and mixed uniformly to obtain a polyisocyanate oligomer having a solid content of 75% by weight. Its viscosity is 2300 mPa · s at 25 ° C, NC
O equivalent was 367.

Comparative Example 2 1,3-BIC743.0 was placed in a 1-liter flask equipped with a reflux condenser, a stirring rod, a thermocouple, and a dropping funnel.
g (2.58 mol), and heated and maintained at 60 ° C. under a nitrogen stream. Tetramethylammonium 2-ethylhexanoate (35% ethyl cellosolve solution) 1.40
g was added dropwise. The reaction solution was reacted at 60 to 70 ° C. for 1 hour, and 0.70 g of phosphoric acid was added to terminate the reaction. After the reaction, unreacted 1,3-BIC was distilled off at a degree of vacuum of 1 torr to obtain 241.3 g of a polyisocyanate oligomer. The content of 1,3-BIC was 0.4% by weight.
The number average molecular weight of this polyisocyanate oligomer is 6
41. Butyl acetate is added to this polyisocyanate oligomer, mixed uniformly, and the solid content concentration is 70% by weight.
Was obtained. Its viscosity is 2
At 5 ° C., 270 mPa · s and the NCO equivalent was 314.

Test Results Examples 1 and 2 The polyisocyanate oligomers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were combined with an acrylic polyol (Acridic A801 manufactured by Dainippon Chemical Industries, Ltd.) by NCO / O
H = 1.0, dry film thickness of 20 to 30 μm
m on a mild steel sheet surface-treated to give
After drying at 50 ° C. and 50% RH for 7 days, a transparent coating film was obtained.
This coating film was subjected to a performance test based on JIS K5400 and JIS Z2251. The results are shown in Tables 1 and 2.

[0019]

(Test result example 1) Complete drying time Erichsen value Dupont impact value Example 1 155 minutes 8 mm or more 20 cm Comparative example 1 180 minutes 0.5 mm 10 cm

[0020]

(Test result example 2) Complete drying time Knoop hardness of surface Dupont impact value Example 2 70 minutes 12.3 20 cm Comparative example 2 80 minutes 9.74 10 cm

The measured values in Tables 1 and 2 were measured according to the following methods. Complete drying time: Based on JISK5400. Erichsen value: The maximum value was 8 mm according to JIS K5400. DuPont impact value: Based on JISK5400. Knoop hardness: Based on JISZ2251, weight 0.
2452N, and the holding time was 10 seconds.

From the results in Tables 1 and 2, it is found that
It can be seen that the polyisocyanate oligomer derived from 4-bis (isocyanatomethyl) cyclohexane gives a cured film having good drying time, adhesion to a coated plate, and surface hardness.

[0023]

The use of the polyisocyanate oligomer derived from 1,4-bis (isocyanatomethyl) cyclohexane of the present invention provides a coating film having excellent weather resistance, a short drying time, and good adhesion to a substrate. Can be obtained. Therefore, the polyisocyanate oligomer of the present invention can be used very advantageously for paints, adhesives, binders and the like.

Claims (2)

[Claims] 1. A 1,4-bis (isocyanatomethyl)
Number average molecular weight 300 to 2 derived from cyclohexane
A polyisocyanate oligomer in the range of 0000. 2. 1,4-bis (isocyanatomethyl)
Number average molecular weight 300 to 2 derived from cyclohexane
A polyurethane paint comprising a polyisocyanate oligomer in the range of 0000 and a polyol.