JP2997307B2 - Polyisocyanate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyisocyanate having particularly useful workability and excellent weatherability which is used in the field of paints for automobiles, buildings, electric appliances and the like. is there.

[Prior Art] Polyisocyanates derived from saturated hydrocarbon diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate are used as non-yellowing polyisocyanates, particularly as curing agents for polyurethane resins having excellent weather resistance.

Among them, polyisocyanates having an isocyanurate structure in particular are known to have better weather resistance and durability than burette-type and adduct-type polyisocyanates because of high chemical stability of the isocyanurate ring. ing.

As described above, since polyisocyanates having an isocyanurate structure have extremely excellent properties, they are desired to be used for a wider range of industrial uses.

However, when used as a coating of a polyisocyanate having this isocyanurate structure, it is necessary to dilute with a highly soluble and highly toxic organic solvent such as ethyl acetate, toluene or xylene. There is a serious danger to the environment, and in the case of repair work, etc., there is a risk of attacking the base coat.

Therefore, with regard to the polyisocyanate with excellent weather resistance which can be diluted with a non-polar organic solvent which does not affect the working environment at the time of painting work and does not attack the undercoat film, it has been obtained by reacting various diols and diisocyanates so far. Are proposed.

With respect to this diol, for example, JP-A-62-209124 discloses a polyester polyol containing 12-hydroxystearic acid as an essential component, JP-A-1-149821 discloses a saturated polybutadienediol, and JP-A-2-1058 discloses a diol.
No. 12 proposes an ester diol.

[Problems to be solved by the invention]

These proposals have made it possible to obtain a compound having excellent solubility in non-polar organic solvents, but have insufficient solubility in non-polar solvents such as mineral spirits, which have particularly low dissolving power.

[Means for solving the problem]

The present inventors have conducted intensive studies on the above-mentioned conventional technology in search of a novel polyisocyanate having excellent solubility in a non-polar organic solvent having a particularly low dissolving power, such as mineral spirits, and as a result, a specific diol and diisocyanate were reacted. The present inventors have found that the polyisocyanate having an isocyanurate structure obtained thereby meets the above-mentioned object, and completed the present invention.

That is, the present invention provides a diisocyanate composed of hexamethylene diisocyanate alone or a mixture of hexamethylene diisocyanate and isophorone diisocyanate, and a diol containing a compound represented by the following formula (1) as a main component in the presence of an isocyanuration catalyst. At
The component derived from the compound represented by the formula (1) is 10 to 50.
It is a polyisocyanate having an isocyanurate structure obtained by reacting within the range of weight%.

(However, R ₁ and R ₂ are alkyl groups, R ₃ and R ₄ are alkylene groups, and R ₁ + R ₂ + R ₃ + R ₄ = C _28. ) In the present invention, the formula (1) The diol compound represented by ()) is a diol containing no unsaturated bond obtained by hydrogenating dimer acid, and specific examples include dimer diol (trade name, manufactured by Arakawa Industry Co., Ltd.).

In the present invention, in order to obtain a polyisocyanate having an isocyanurate structure, it is necessary to charge the diisocyanate in excess with respect to the diol.
Diisocyanate is used in a molar ratio of 4 to the diol charge.
It is preferable to carry out the reaction by charging at least twice.

And, in the polyisocyanate obtained in the present invention,
It is necessary that 10 to 50% by weight of a component derived from a diol obtained by reducing dimer acid is contained,
Preferably it is 20 to 40% by weight. When the component derived from the diol is less than 10% by weight, the solubility in a non-polar organic solvent is insufficient, which is not preferable. When the component is more than 50% by weight, the isocyanate content of the polyisocyanate is reduced. And it is not preferable from an economic viewpoint.

In addition, it is generally said that the isocyanuration reaction is carried out via a uretdione structure which is a cyclic dimer having low thermal stability, or a uretdione structure is generated as a side reaction. Therefore, when the reaction is stopped at a low conversion rate, the uretdione concentration in the product tends to increase. Therefore, in order to suppress the uretdione content in the product, it is necessary to select a catalyst having a small amount of uretdione residue. Suitable catalysts for such conditions include, for example, tetramethylammonium, tetraethylammonium, tetraalkylammonium hydroxides and organic weak acid salts such as tetrabutylammonium, for example, trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, Hydroxyalkylammonium hydroxides and organic weak acid salts such as triethylhydroxyethylammonium, for example, acetic acid, caproic acid, octylic acid, alkali metal salts of alkylcarboxylic acids such as myristic acid, and tin, zinc and lead of the above alkylcarboxylic acids And the like, for example, an aminosilyl group-containing compound such as hexamethyldisilazane.

The catalyst concentration varies depending on the catalyst used and the reaction concentration, but is usually selected from the range of 10 to 1,000 ppm based on diisocyanate.

In order to obtain the polyisocyanate in the present invention,
It is necessary to stop the progress of the reaction at an early stage. However, the cyclic trimerization of the isocyanate group has an extremely high initial reaction rate, and it is difficult to stop the progress of the reaction at the initial stage. Therefore, the reaction conditions, especially the amount and method of addition of the catalyst, must be carefully monitored. You have to choose. For example, a method of adding the catalyst at regular intervals for each time is recommended as a suitable method.

The reaction may or may not use a solvent. When a solvent is used, a solvent having no reaction activity for the isocyanate group should be selected. Specific examples of the solvent include aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate.

The reaction temperature is usually selected from the range of 20 to 160 ° C, preferably 40 to 120 ° C.

The progress of the reaction can be monitored by NCO% measurement, infrared spectroscopy, refractive index measurement, etc. of the reaction solution.

Further, if the conversion reaction to isocyanurate proceeds too much, the viscosity of the product increases, the content of cyclic trimer of isocyanurate decreases, and a product having the desired physical properties cannot be obtained. It is preferable to keep it at about 25% or less.

Once the reaction has reached the desired conversion, for example, sulfuric acid,
The reaction is stopped by adding a catalyst deactivator such as phosphoric acid. After stopping the reaction, if necessary, removing the deactivated catalyst, excess diisocyanate and solvent are removed to obtain a product. The removal of the diisocyanate and the solvent is performed by, for example, a thin film evaporator or a solvent extraction method.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.

 The physical properties of the products were determined by the following methods.

 The viscosity was measured at 23 ° C. using a B-type viscometer.

The NCO content was determined by adding excess di-n-butylamine to the product and reacting it with the isocyanate, and then back titrating the amount of unreacted amine with hydrochloric acid.

The amounts of residual HDI and residual IPDI were determined by an internal standard method using a gas chromatograph (manufactured by Hitachi, Ltd., FID detector).

The IR measurement was performed by a rock salt plate coating method using a Fourier transform infrared spectrometer (manufactured by Shimadzu Corporation).

Example 1 600 g of hexamethylene diisocyanate (hereinafter abbreviated as HDI) and dimadiol (manufactured by Arakawa Chemical Industries, Ltd.) were placed in a four-necked flask equipped with a stirrer, a condenser, and a thermometer.
120 g of a trade name and property values described in a catalog: specific gravity = 0.9, hydroxyl value = 200, boiling point = 210 ° C., purity = 97%) were charged, and a urethanization reaction was carried out at 80 ° C. for 2 hours with stirring.

Then, after the temperature was lowered to 60 ° C., 0.2 g of tetramethylammonium capryate was added in portions as a catalyst every 30 minutes.

After the isocyanurate-forming reaction was performed at 60 ° C. for 4 hours, 0.15 g of 89% phosphoric acid was added as a terminator to terminate the reaction.
Furthermore, the temperature was raised to 90 ° C., heating was continued for 1 hour, and then the mixture was cooled to room temperature. As a result, tetramethylammonium phosphate as a deactivating catalyst was deposited.

After removing this precipitate by filtration, the first time, 0.8 mmHg / 150 ° C, the second time 0.1 mmHg / 1
Unreacted HDI was removed and recovered at 60 ° C.

The product obtained was a pale yellow, clear liquid with a viscosity of 3,500 cP, an NCO content of 14.2% and a free HDI of 0.1%. IR measurement of this product showed absorption of an isocyanurate ring at around 1680 cm ^-1 .

Further, since the yield of the product was 340 g, the amount of the component derived from the diol contained in the obtained polyisocyanate was 35%.

The obtained polyisocyanate is a non-polar solvent, mineral spirit [Katayama Chemical Co., Ltd., aniline point 52
C) was 500% or more.

Example 2 350 g of HDI, 100 g of isophorone diisocyanate and 60 g of dimer diol were charged into a four-necked flask equipped with a stirrer, a condenser and a thermometer, and the reaction was carried out in the same manner as in Example 1. As a result, a pale yellow transparent product was obtained.

The viscosity of this product was 8,000 cP, the NCO content was 16.2%, and the total amount of free HDI and free IPDI was 0.2%. The product was subjected to IR measurement. As a result, absorption of an isocyanurate ring was observed at around 1680 cm ⁻¹ .

Further, since the yield of the product was 240 g, the amount of the component derived from the diol contained in the obtained polyisocyanate was 25%.

The dilution ratio of the obtained polyisocyanate with respect to mineral spirit as a non-polar solvent was 500% or more.

Comparative Example 1 1,3-butanediol 1 was used in place of 120 g of dimer diol.
Except using 20g, it carried out similarly to Example 1. As a result, a pale yellow transparent product was obtained.

The product had a viscosity of 2,900 cP, an NCO content of 16.0% and a free HDI of 0.1%. IR measurement of this product showed absorption of an isocyanurate ring at around 1680 cm ^-1 .

Further, since the yield of the product was 360 g, the amount of the component derived from the diol contained in the obtained polyisocyanate was 33%.

The resulting polyisocyanate had no solubility in mineral spirit, a non-polar solvent.

Comparative Example 2 The same device as in Example 1 was charged with only 600 g of HDI, and an isocyanurate-forming reaction was performed in the same manner as in Example 1.
This resulted in a pale yellow, transparent product.

The viscosity of this product was 1,300 cP, the NCO content was 23.0%, the free HDI was 0.1%, and the yield of the product was 130 g. IR measurement of this product showed absorption of an isocyanurate ring at around 1680 cm ^-1 .

The resulting polyisocyanate had no solubility in mineral spirit, a non-polar solvent.

〔The invention's effect〕

The polyisocyanate having an isocyanurate structure of the present invention is remarkably excellent in solubility in a solvent having a particularly low polarity such as mineral spirits.

Therefore, when used as a curing agent for a polyurethane coating, there is a great advantage that the amount of a polar solvent used can be reduced. In addition, it is necessary to design an excellent paint composition that has the advantage of preventing the occurrence of defects such as peeling, shrinkage, etc. of the coating film at the time of recoating, and the advantage that there is no risk of attacking the surface of the plastic substrate. It becomes possible.

Also, because it also has excellent heat resistance, for example,
It is extremely useful as a curing agent for polyurethane paints such as paints, adhesives, coating materials, casting materials, elastomers and foams.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 18 / 32,18 / 79 C09D 175/04

Claims (1)

(57) [Claims] 1. A diisocyanate consisting of hexamethylene diisocyanate alone or a mixture of hexamethylene diisocyanate and isophorone diisocyanate and a diol containing a compound represented by the following formula (1) as a main component, in the presence of an isocyanuration catalyst. A polyisocyanate having an isocyanurate structure obtained by reacting a component derived from a diol within a range of 10 to 50% by weight. (However, R ₁ and R ₂ are alkyl groups, R ₃ and R ₄ are alkylene groups, and R ₁ + R ₂ + R ₃ + R ₄ = C _28. )