JP3228801B2 - Process for producing isocyanurate group-containing polyisocyanate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyisocyanate having an isocyanurate ring, and more particularly to a method for stably producing a polyisocyanate having an isocyanurate ring.

[0002]

2. Description of the Related Art Polyisocyanates having isocyanurate rings having excellent weather resistance, heat resistance and chemical resistance in the molecule are used as raw materials for polyurethanes such as paints, adhesives, elastomers, artificial leathers, foams, and plastic lenses. Used as a material. Regarding the production method, JP-A-2-25871, JP-A-2-11554, JP-A-2-3682, JP-A-2-110123, JP-A-2-2-2
50872, JP-A-2-6480, JP-A-2-32
068, JP-A-2-6454, JP-A-1-2974
No. 20, JP-A-1-149821, JP-A-61-11
1371, JP-A-60-181078, JP-A-60-18
Many patent applications have been filed, such as JP-A-181114.

The catalysts proposed by these patent applications are quaternary ammonium containing hydroxyalkyl groups,
Quaternary ammonium hydroxide, hydroxyalkyl group-containing quaternary ammonium carboxylate, and fluorinated quaternary ammonium. Among these catalysts, the quaternary ammonium containing a hydroxyalkyl group has a high self-decomposition property and causes coloring, and the catalyst activity deteriorates due to decomposition, oxidation, and the like during storage of the catalyst. Since quaternary ammonium hydroxide is strongly alkaline, it has a problem that it easily reacts with carbon dioxide in the air during storage of the catalyst, and a gel is generated during the reaction and the reaction does not proceed uniformly.

Furthermore, the carboxylate of quaternary ammonium having an alkyl group having 1 to 4 carbon atoms and having a total of 4 to 12 carbon atoms described in JP-A-63-575577 is excellent. Although this is a catalyst system, the catalyst itself has a high hygroscopicity, and during storage of the catalyst, a decrease in activity that is considered to be caused by moisture absorption occurs. For this reason, in order to maintain the activity of the catalyst at a constant level and to stably produce the catalyst, great care must be taken in storage and handling of the catalyst.

[0005]

An object of the present invention is to provide a method for stably producing a polyisocyanate having an isocyanurate ring.

[0006]

Means for Solving the Problems As a result of intensive studies and studies, the present inventors have found a method for solving the above-mentioned problems by using a tetraalkylammonium carboxylate having a specific alkyl group, and have reached the present invention. Was. That is, the present invention relates to a monomer diisocyanate, and a part of the isocyanate group of at least one isocyanate compound selected from a pre-urethane reaction product of the monomer diisocyanate and a 1-3-functional alcohol. In the synthesis of a polyisocyanate having an isocyanurate ring by performing a trimerization reaction and then terminating the reaction with a catalyst poisoning substance, using a tetraalkylammonium carboxylate represented by the following formula (1) as a catalyst: And a process for producing a polyisocyanate having an isocyanurate ring.

[0007] ^{R 1 R 2 R 3 R 4} N + / R 5 COO - ··· (1) ( wherein ^{R 1, R 2, R 3} , R 4 , at least one of its number 4 or more carbon atoms And R ¹ ,
When the total number of carbon atoms in the formulas R ² , R ³ and R ⁴ is from 13 to 50 ,
An aralkyl group, R ⁵ represents an alkyl group, a phenyl group or a benzyl group having 1 to 18 carbon atoms. In the present invention, the isocyanate compound is a monomeric diisocyanate such as an aliphatic isocyanate and an aromatic isocyanate, and a pre-urethane reaction product of the monomeric diisocyanate and a 1-3-functional alcohol.

Examples of the aliphatic diisocyanate include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), and 2,4,4
(Or 2,2,4) -trimethylhexamethylene diisocyanate (TMDI). Examples of aromatic diisocyanates include tolylene diisocyanate (TD
I), diphenylmethane diisocyanate (MDI),
Toluidine diisocyanate (TODI), xylylene diisocyanate (XDI) and naphthalene diisocyanate (NDI).

These monomeric diisocyanates are arbitrarily selected depending on the purpose of use of the final product, but aliphatic diisocyanates are particularly preferred when non-yellowing is required. Examples of the 1-3-functional alcohol include lower aliphatic monohydric alcohols such as methanol, ethanol and isopropanol, as well as ethylene glycol, propylene glycol, butanediol, glycerin, 1,2,2
Lower aliphatic polyhydric alcohols such as 6-hexanetriol; and polyester polyols and polyether polyols having a molecular weight of about 200 to 10,000.

The isocyanate compound to be subjected to the trimerization reaction may be a mixture comprising at least two or more of the above-mentioned isocyanate compounds. As the tetraalkylammonium carboxylate, for example, tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraoctylammonium,
Acetate, propionate, hexanoate, 2-ethylhexanoate, caprate, naphthenate, myristate, stearate, benzoate, etc., such as tetradecyl ammonium, hexadecyl trimethyl ammonium, hexadecyl benzyl dimethyl ammonium, etc. Acid salts and the like. The catalyst concentration depends on the catalyst used and the reaction temperature, but is usually selected from the range of 10 ppm to 1% based on the monomer diisocyanate.

The progress of the reaction can be monitored by measuring the NCO% of the reaction solution, measuring the infrared spectrum, measuring the refractive index, and the like. When the reaction reaches the desired conversion, the catalyst is deactivated by charging a catalyst poisoning substance to stop the reaction. If the conversion reaction to isocyanurate progresses too much, pentamerization and heptamerization occur partially with trimerization, and the viscosity of the product increases, so that the conversion of the isocyanate compound is 5 to 70%.
% In general, and preferably in the range of 10 to 60%.

As the catalyst poisoning substance, for example, acidic substances such as hydrochloric acid, phosphoric acid, sulfuric acid, dichloroacetic acid, benzoyl chloride and acetyl chloride are used. The amount of the catalyst poisoning substance is preferably 0.4 to 100 equivalents, more preferably 0.6 to 40 equivalents per equivalent of the catalyst.
Is equivalent. The reaction may or may not use a solvent. When a solvent is used, a solvent which does not have a reaction activity for the isocyanate group should be selected.

[0013] The reaction temperature is usually selected from the range of 20 to 160 ° C, preferably 40 to 120 ° C. After stopping the reaction, excess monomeric diisocyanate and solvent are removed to obtain a product. The removal of the monomer diisocyanate and the solvent is performed by, for example, a thin film distillation method or a solvent extraction method.

[0014]

The present invention will be described more specifically with reference to the following examples. The storage test of the catalyst was performed as follows. Note that the present invention is not limited to these. (Catalyst storage test) The catalyst is stored open at one week at 20 ° C and 65% RH, and the amount of catalyst required until the conversion reaches 20% in the synthesis of polyisocyanate is compared before and after the test to ensure stable storage. Sex was judged.

[0015]

Example 1 (Synthesis of catalyst) Capric acid and n-butanol were added to an aqueous solution of tetrabutylammonium hydroxide, followed by azeotropic distillation under reduced pressure to prepare a 30% tetrabutylammonium capryate / n-butanol solution to synthesize polyisocyanate. Used for reaction. (Synthesis of polyisocyanate) A glass four-necked flask equipped with a thermometer, a stirrer, and a nitrogen sealed tube was charged with 1000 g of hexamethylene diisocyanate as a monomeric diisocyanate, and the air in the flask was replaced with nitrogen. Heat to 60 ° C. with stirring. The catalyst was gradually added until the conversion of hexamethylene diisocyanate became 20% by the measurement of the refractive index of the reaction solution, and when the conversion reached 20%, 0.5 g of an 85% aqueous phosphoric acid solution was added to stop the reaction. . In the catalyst before the storage test, the required amount of the catalyst was 300 ppm based on hexamethylene diisocyanate. For the catalyst after the storage test, the required catalyst amount is 305 ppm
And almost no decrease in activity was observed.

[0016]

Example 2 Tetrahexylammonium acetate / n-butanol was synthesized in the same manner as in Example 1, and the procedure of Example 1 was repeated for the synthesis of polyisocyanate. Before the storage test, the required amount of catalyst was 450 ppm. After the storage test, the required catalyst amount was 455 ppm
And almost no decrease in activity was observed.

[0017]

Example 3 Example 3 except that hexadecyltrimethylammonium propionate was used instead of tetrabutylammonium caprate. Step 1 was repeated.
Before the storage test, the required amount of catalyst was 310 ppm. After the storage test, the required catalyst amount is 310 pp
m, and almost no decrease in activity was observed.

[0018]

[Comparative Example 1] Instead of tetrabutylammonium caprate, hydroxyethyltrimethylammonium /
The procedure of Example 1 was repeated except that n-butanol was used. Before the storage test, the required catalyst amount was 50 ppm
Met. After the storage test, the required amount of catalyst is 100
ppm, and a remarkable decrease in activity was observed.

[0019]

Comparative Example 2 The procedure of Example 1 was repeated except that tetrapropylammonium caprate was used instead of tetrabutylammonium caprate. Before the storage test, the required amount of catalyst was 250 ppm. After the storage test, the required catalyst amount was 330 ppm, and a remarkable decrease in the activity was observed.

[0020]

According to the present invention, in the synthesis of a polyisocyanate having an isocyanurate ring, a more stable production can be achieved by using a tetraalkylammonium carboxylate having a specific alkyl chain as a catalyst.

Claims (1)

(57) [Claims] 1. An isocyanate group of at least one isocyanate compound selected from a monomeric diisocyanate and a pre-urethane reaction product of a monomeric diisocyanate and a 1-3-functional alcohol. In the synthesis of polyisocyanate having an isocyanurate ring by performing a quantification reaction and then terminating the reaction with a catalyst poisoning substance, it is necessary to use a tetraalkylammonium carboxylate represented by the following formula (1) as a catalyst. A method for producing an isocyanurate group-containing polyisocyanate. ^{R 1 R 2 R 3 R 4} N + / R 5 COO - ··· (1) ( wherein ^{R 1, R 2, R 3} , R 4 is at least one alkyl group having 4 or more carbon atoms in its And R ¹ ,
When the total number of carbon atoms in the formulas R ² , R ³ and R ⁴ is from 13 to 50 ,
An aralkyl group, R ⁵ represents an alkyl group, a phenyl group or a benzyl group having 1 to 18 carbon atoms. )