JPH04130171A - Curing agent for polyurethane coating material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a curing agent for polyurethane paints that is particularly useful and has excellent workability and weather resistance and is used in the field of paints for automobiles, buildings, electrical appliances, etc. It is related to.

[Conventional technology]

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 with excellent weather resistance.

Among them, polyisocyanates with an isocyanurate structure are known to have superior weather resistance and durability compared to buret-type and adduct-type polyisocyanates because the isocyanurate ring has high chemical stability. ing.

As described above, polyisocyanate having an isocyanurate structure has extremely excellent properties.
-It is hoped that it will be used in a wide range of industrial applications.

However, when polyisocyanates with this isocyanurate structure are used as paints, it is necessary to dilute them with organic solvents such as ethyl acetate, toluene, or xylene, which have strong solvent power and are highly toxic. This poses a serious problem to the environment, and in the case of repair work, there is a risk of damaging the underlying paint film.

Therefore, we have developed a curing agent for polyurethane paints that has excellent weather resistance and can be diluted with a non-polar organic solvent that does not cause any hindrance to the working environment during painting work and does not attack the underlying paint film, by reacting various diols and diisocyanates. A method using polyisocyanate obtained by

As this diol, for example, JP-A-62-209124
In the publication, a polyester polyol containing 12-hydroxystearic acid as an essential component is disclosed in JP-A-1-14
9821 proposes saturated polybutadiene diol, and JP-A-2-105812 proposes ester diol.

[Problem to be solved by the invention]

These proposals have made it possible to obtain products that can be diluted with non-polar solvents, but these become cloudy when diluted with non-polar solvents that have particularly weak dissolving power, such as mineral spirits, and cannot be used.

[Means to solve the problem]

In view of the problems of the prior art described above, the present inventors conducted extensive research in search of a new curing agent for polyurethane paints that can be diluted with a non-polar solvent with particularly weak dissolving power such as mineral sulfuric acid. The inventors have discovered that a composition consisting of a polyisocyanate having an isocyanurate structure obtained by reacting a diol with a diisocyanate and a non-polar organic solvent satisfies the above-mentioned purpose, and has completed the present invention.

That is, in the present invention, a diisocyanate consisting of hexamethylene diisocyanate alone or a mixture of hexamethylene diisocyanate and isophorone diisocyanate is mixed with a diol obtained by reducing dimer acid, and in the presence of an isocyanurate catalyst, the diol is converted into a diisocyanate. This is a curing agent for polyurethane paints consisting of a polyisocyanate having an isocyanurate structure obtained by reacting 10 to 50% by weight of the derived constituent components and a nonpolar organic solvent.

The diol obtained by reducing the dimer acid used in the present invention is a diol that does not contain an unsaturated bond and is obtained by hydrogenating the dimer acid. A specific example is dimadiol (manufactured by Arayo Kagaku Kogyo ■, trade name), which has a compound having the following structure as a main component.

(R++Rt+Rs+Rn=Cz@) In the present invention, in order to obtain a polyisocyanate having an isocyanurate structure, it is necessary to charge diisocyanate in excess of diol, and in practice, the molar ratio of diisocyanate to the amount of diol charged is It is preferable to carry out the reaction by charging at least 4 times as much.

In addition, it is necessary that the polyisocyanate obtained in the present invention contains 10 to 50% by weight of a component derived from a diol obtained by reducing dimer acid,
Preferably it is 20 to 40% by weight.

If the component derived from diol is less than 10% by weight, the solubility in non-polar organic solvents is insufficient, which is undesirable.
Moreover, if it exceeds 50% by weight, the isocyanate content of the polyisocyanate decreases, which is not preferable from a resin design standpoint, and also from an economic standpoint.

In addition, the isocyanurate reaction is a cyclic 2-molecule with low thermal stability.
It is generally said that the reaction occurs via the uretdione structure, which is a polymer, or that the uretdione structure also occurs as a side reaction. Therefore, if the reaction is stopped at a low conversion rate,
The concentration of uretdione in the product tends to be high. Therefore, in order to suppress the uretdione content in the product, it is necessary to select a catalyst that leaves less uretdione remaining.

Catalysts suitable for such conditions include (1) hydroxides and organic weak acid salts of tetraalkylammonium such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium; (2) such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, and triethylhydroxypropyl; Hydroxides and organic weak acid salts of hydroxyalkylammonium such as ammonium and triethylhydroxyethylammonium, ■Alkali metal salts of alkyl carboxylic acids such as acetic acid, caproic acid, octylic acid, myristic acid, etc., and ■tin of the above alkyl carboxylic acids. , metal salts such as zinc and lead; (2) For example, aminosilyl group-containing compounds such as hexamethyldisilazane.

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

In order to obtain the polyisocyanate of the present invention, it is necessary to stop the progress of the reaction at an early stage.

However, in the cyclic trimerization of isocyanate groups, the initial reaction rate is very fast, so it is difficult to stop the reaction at an early stage, so the reaction conditions, especially the amount and method of catalyst addition, must be carefully selected. You need to choose.

For example, a method of adding the catalyst in portions at regular intervals is recommended as a suitable method.

The reaction may be carried out with or without a solvent. Naturally, when using a solvent, one should be selected that does not have reactive activity toward isocyanate groups. Specific examples of solvents include:
Examples include aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate.

The reaction temperature is usually 20-160°C, preferably 40-160°C.
Selected from a range of 20°C.

The progress of the reaction can be tracked by measuring the NC0% of the reaction solution, infrared spectroscopy, refractive index measurement, etc.

In addition, if the conversion reaction to isocyanurate progresses too much,
Since the viscosity of the product increases and the isocyanurate cyclic trimer content decreases, making it impossible to obtain a product with desired physical properties, it is preferable to keep the conversion rate of the reaction at about 25% or less.

When the reaction reaches the desired conversion rate, a catalyst deactivator such as sulfuric acid or phosphoric acid is added to stop the reaction. After stopping the reaction, if necessary, after removing the deactivated catalyst, excess diisocyanate and solvent are removed. The diisocyanate and solvent are removed by, for example, a thin film evaporation can or a solvent extraction method.

The obtained polyisocyanate is dissolved in a non-polar organic solvent to obtain a product. The solid content of the product is usually 50% to 90%.
It is about %. It is also possible to further dilute this with a non-polar organic solvent.

The non-polar organic solvent used in the present invention has an aniline point of lO~
It is a non-polar organic solvent with low toxicity and weak dissolving power within the range of 70°C. Typical examples include House (manufactured by Shell Chemical Co., Ltd., aniline temperature: 15°C), Swazol 310 (
Manufactured by Maruzen Sekiyu Co., Ltd., aniline point 16°C), Ftsnaphtha N
o, 6 (manufactured by Exxon Chemical Co., aniline point 43”C)
, LAWS (manufactured by Shell Chemical Co., aniline point 44°C)
, Mineral spirit (aniline point 52°C), Eftunaphtha 5 (manufactured by Exxon Chemical Co., aniline point 55°C)
), petroleum hydrocarbon organic solvents such as Pegasol 3040 (manufactured by Mobil Oil Company, aniline point 55°C), methylcyclohexane (aniline point 40°C), ethylcyclohexane (aniline point 44°C), and the like.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by the Examples.

In addition, the physical property values of the product were determined by the following method.

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

The NGO content was determined by adding excess di-n-butylamine to the product and reacting it with 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 carried out using a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation) using a rock salt plate coating method. Example 1 600 g of hexamethylene diisocyanate (hereinafter abbreviated as HDI) and dimmerdiol [Arayo Kagaku Kogyo Co., Ltd.
Product name, product name, property values listed in the catalog: Specific gravity = 0.9,
Hydroxyl value = 2QO, boiling point = 210'' C1 purity = 97%)
120 g was charged and the urethane reaction was carried out at 80°C for 2 hours with stirring.

Then, after lowering the temperature to 60°C, 0.2 g of tetramethylammonium caprate was divided into 3 portions as a catalyst.
Added every 0 minutes.

After carrying out the isocyanurate reaction at 60°C for 4 hours,
The reaction was stopped by adding 0.15 g of 89% phosphoric acid as a terminator. Further, the temperature was raised to 90°C, heating was continued for 1 hour, and then cooled to room temperature to precipitate tetramethylammonium phosphate, which is a deactivated catalyst.

After removing this precipitate by filtration, the first time was 0.8+++mHg/150°C using a falling film evaporation can.
12th unreacted H under the condition of 0.1mFIg/160℃
DI was removed and collected.

The product obtained was a pale yellow, clear liquid with a viscosity of 3.500 cP, an NCO content of 14.2%, and free H
DI was 0.1%. When this product was subjected to IR measurement, absorption of isocyanurate rings was observed near 1680C1-'.

Furthermore, since the yield of the product was 340 g, the amount of diol-derived components contained in the obtained polyisocyanate was 35%.

The obtained polyisocyanate was mixed with a non-polar solvent Swasol 310 [manufactured by Maruzen Sekiyu ■, trade name, aniline point 16].
0°C] to 75% to obtain a transparent polyisocyanate solution.

This polyisocyanate solution could be diluted to 20% or less using mineral spirit (manufactured by Katayama Kagaku ■, aniline point 52''C) as a diluting solvent.

In addition, this polyisocyanate solution was added to a non-polar solvent-soluble safflower oil-modified medium oil alkyd resin [manufactured by Dainippon Ink Chemical Co., Ltd., product name: Beccosol J-557, standard property values listed in the catalog: non-volatile content = 50± 1%, solvent = Swasol 310, phthalic acid content - 30%, oil - safflower oil, oil length = 51%. Viscosity = v -x, number of colors = 7 or less, acid value -8 or less, measured value of hydroxyl value = 60)
When a resin face prepared by blending equivalent amounts such that CO10H=1 was applied to a glass plate, a transparent cured coating film was obtained.

Example 2 1500 g of Ho and 100 g of isophorone diisocyanate were placed in a four-bottle flask equipped with a stirrer, a condenser, and a thermometer.
g and 60 g of dimadiol were charged, and the reaction was carried out in the same manner as in Example 1. As a result, a pale yellow and transparent product was obtained.

The product had a viscosity of 4.0 OOcP, an NCO content of 16.5%, and a total amount of free HDI and free IPDI of 0.2%. When this product was subjected to IR measurement, absorption of isocyanurate rings was observed near 1680C11-'.

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

The obtained polyisocyanate was diluted to 75% with Swasol 310, a non-polar solvent, to obtain a transparent polyisocyanate solution.

This polyisocyanate solution could be diluted to 20% or less using mineral spirit (manufactured by Katayama Kagaku ■, aniline point: 43° C.) as a diluting solvent.

Also, what is the name of this polyisocyanate? When a resin face prepared by adjusting the equivalent ratio of 9 liquid to NGO10H = 1 to Pencosol J-557, a safflower oil-modified alkyd resin in oil that is soluble in a non-polar solvent, was applied to a glass plate.
A transparent cured coating was obtained.

Comparative Example 1 The same procedure as in Example 1 was carried out except that 120 g of 1,3-butanediol was used instead of 120 g of dimadiol. As a result, a pale yellow and 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%. When this product was subjected to IR measurement, absorption of isocyanurate rings was observed around 1680 cm-'.

Furthermore, since the yield of the product was 360 g, the amount of diol-derived components contained in the obtained polyisocyanate was 33%.

When the obtained polyisocyanate was diluted to 90% or less with Swasol 310, which is a non-polar solvent, it became cloudy, and a diluted solution could not be prepared.

Further, an attempt was made to dilute a polyisocyanate solution diluted to 75% with Solgenso 100 (manufactured by Exxon Chemical), which has relatively strong polarity, with mineral spirit, but the solution became cloudy and could not be diluted at all.

Comparative Example 2 Only 600 g of HDI was charged into the same apparatus as in Example 1, and an isocyanurate reaction was carried out in the same manner as in Example 1. As a result, a pale yellow and transparent product was obtained.

The product had a viscosity of 1,300 cP, an NCO content of 23.0%, a free IDI of 0.1%, and a product yield of 130 g. When this product was subjected to IR measurement, absorption of isocyanurate rings was observed around 1680 cm-'.

When the obtained polyisocyanate was diluted to 90% or less with Swasol 310, which is a non-polar solvent, it became cloudy, and a diluted solution could not be prepared.

In addition, an attempt was made to dilute a polyisocyanate solution diluted to 75% with Tsurpez 100 (manufactured by Exxon Chemical), which has relatively strong polarity, with mineral spirit, but the solution became cloudy and could not be diluted at all.

〔Effect of the invention〕

The curing agent for polyurethane of the present invention can be diluted with a particularly low polar solvent such as mineral spirit, and has extremely excellent compatibility with relatively low polar resins. For this reason, it is necessary to design an excellent paint composition that has the advantage of preventing the occurrence of defects such as flaking and sagging of the paint film during overcoating, and also has the advantage of not having to worry about damaging the surface of the plastic base material. becomes possible.

It also has excellent heat resistance, so it can be used in paints, adhesives, coating materials, casting materials, elastomers, etc.
It is extremely useful as a curing agent for polyurethane resins such as foam materials.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] A diisocyanate consisting of hexamethylene diisocyanate alone or a mixture of hexamethylene diisocyanate and isophorone diisocyanate is mixed with a diol obtained by reducing dimer acid, and in the presence of an isocyanurate catalyst, the constituent components derived from the diol are reduced to 10 A polyisocyanate having an isocyanurate structure obtained by reacting within a range of 50% by weight,
A curing agent for polyurethane paints consisting of a non-polar organic solvent.