JPH0370723A - Production of aromatic polyisocyanurate compound - Google Patents

Abstract

PURPOSE:To improve compatibility, etc., with a principal agent by using a specific diol, etc., in subjecting an aromatic polyisocyanate and a diol to urethanating reaction and then trimerization reaction in the presence of a catalyst and providing an aromatic polyisocyanurate compound. CONSTITUTION:An aliphatic diol (preferably 2-ethyl-1,3-hexanediol, etc.) having >=2 hydrocarbon substituent groups is dropped into an aromatic polyisocyanate (e.g. 2,4-tolylene diisocyanate) mixed with an inert solvent (e.g. ethyl acetate) to carry out urethanating reaction. A trimerization catalyst (preferably triethylamine, etc.) is then dividedly added (preferably 3-5 times) to perform trimerization reaction. A reaction terminator (e.g. phosphoric acid) is subsequently added to terminate the trimerization reaction and afford an aromatic polyisocyanurate with a low coloring degree and hardly any unreacted diisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing aromatic polyisocyanurate compounds.

Aromatic polyisocyanurate compounds have a highly stable chemical structure, and are therefore known to be curing agents for polyurethane paints with excellent curability, heat resistance, and weather resistance.

[Conventional technology]

As a method for producing an aromatic polyisocyanurate compound, a method is known in which urethane modification is performed using an aromatic polyisocyanate and a predetermined amount of polyol, and then a trimerization catalyst is added to perform isocyanuration.

For example, JP-A-60-15419 is characterized in that a diol having a number average of 60 to 500 is used as a polyol in urethanization in order to prevent whitening of the coating film over time when used as a paint.

Furthermore, in JP-A No. 57-2320, a method of using a catalyst is investigated for the purpose of suppressing the cloudiness of the reaction mixture that occurs as the triassidization reaction progresses after urethanization.

[One problem to be solved by the invention] In general, aromatic isocyanurate compounds have higher isocyanate reactivity than aliphatic, alicyclic, or aromatic alicyclic isocyanurate compounds, and are quick-drying with excellent initial drying properties. Known as a mold yellowing type, aromatic isocyanurate compounds obtained by conventional manufacturing methods are effectively used in fields where quick drying is required. However, because of poor compatibility with the polyol used as the base agent, the types of these polyols are limited, making it impossible to produce a variety of efficient and economical urethane paints.

■The degree of coloration during the triassidization reaction is large.

(2) In order to reduce polymers that are unfavorable in compatibility with the main ingredient, isocyanate is used in excess and a complicated process of removing unreacted isocyanate such as distillation and extraction is required.

■The amount of heat generated in the early stage of the reaction is large, requiring heat removal equipment such as an external cooler.

■When used in practical applications for painting, bicycles, architecture, etc.
When used for various parts such as bridges, woodwork products, plywood painting, etc.
In addition to hardness, heat resistance, and weather resistance, paints are required to have a variety of physical properties such as hardness, impact resistance, solvent resistance, and stain resistance. It has various drawbacks, such as being unsatisfactory, and there has not yet been a manufacturing method that can solve all of these problems.

That is, the problem of the present invention is to solve the above-mentioned problems, in other words, the main ingredient (polyol)
It is an object of the present invention to provide a method for producing an aromatic isocyanurate compound which has good compatibility with esters, has a low degree of coloration, has a small amount of unreacted diisocyanate components, and has improved coating performance.

[Means for solving the invention]

In view of the above-mentioned problems, the present inventors have made extensive studies to solve these problems, and have found that as a diol, 2
The compatibility with various main ingredients (polyols) is improved by partially urethanizing a diol having at least one hydrocarbon substituent and then converting it into isocyanurate.
In addition, by adding the catalyst in portions, aromatic polyisocyanurate compounds with low coloration and less unreacted isocyanate can be obtained, and aromatic polyisocyanurate compounds obtained by such a method can be used in paints. The present invention was completed based on the discovery that various physical properties of the coating film were far superior to those of conventional coatings.

That is, the present invention provides a method for producing a urethane prepolymer containing an isocyanurate group by subjecting an aromatic polyisocyanate and a diol to a urethanization reaction and then performing a triassidization reaction in the presence of a catalyst. This is a method for producing aromatic polyisocyanurate, which is an aliphatic diol having two or more hydrocarbon substituents in one molecule, and is characterized in that a catalyst is added in portions.

The present invention will be specifically explained below.

Aromatic polyisocyanates used in the method of the present invention include, for example, 2,44 lylene diisocyanate, 2
．． 6-) lylene diisocyanate, 4,4゛diphenylmethane diisocyanate, l15-naphthalene diisocyanate, 1,4-naphthalene diisocyanate, l,
4-phenylene diisocyanate, 1,3-phenylene diisocyanate, 1-methyl-2,5-phenylene diisocyanate, l-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2 , 4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl 2,5-phenylene diisocyanate, 1-chlorohenzene-2.4-
Diisocyanate, 1-nitrobenzene-2,4-diisocyanate, 2-nitrohenyne-1,4-diisocyanate, l-methoxybenzene-2,4-diisocyanate, 1-ethoxybenzene-2,4-diisocyanate, biphenyl-2,4゛-diisocyanate, 3-3
'-dimethylbiphenyl-4,4'-diisocyanate, 3-3"-dimethoxybiphenyl-4,4"-diisocyanate, diphenylmethane-2,2"-diisocyanate, 3-3'-dichlorodiphenylmethane-4,4'
-diisocyanate, 3,5-dimethyldiphenylmethane-4,4''-diisocyanate, diphenyl ether-2,4''-diisocyanate, diphenyl ether-
Examples include one kind or a mixture of two or more kinds of 4,4'-diisocyanate and the like.

The diol used in the method of the present invention may be any diol having two or more hydrocarbon groups in one molecule, such as 2,2-diethyl-13-propanediol, 22-dimethyl- 1,3-propenediol,
2-n-butyl-2-ethyl-1,3-propanediol, 3-methyl 1,3-butanediol, 2゜2.4-
) dimethyl-1,3-bentanediol, 2. Ethyl-1,3-hexanediol, 2,5-dimethyl-2,
Examples include diols such as 5-hexanediol. Among them, 2-ethyl-1,3-hexanediol, 2,2.4-
) Dimethyl-1,3-bentanediol is preferred.

The amount of these polyols used has an equivalent ratio NGOloll of 2 to 100 relative to the isocyanate.

The urethanization reaction can be carried out in the presence or absence of an inert solvent, but is usually carried out by dropping the diol component into the aromatic polyisocyanate component mixed with an inert solvent while stirring. Ru.

Inert solvents used at this time include ethyl acetate,
Examples include an-butyl acetate, isobutyl acetate, acetone, methyl ethyl ketone, benzene, toluene, and quidylole, and one type or a mixture of two or more of these can be used. The amount used is 0.3 to 4 times the weight of the reaction raw material.

The reaction temperature for urethanization is usually 30-100°C, preferably 50-90°C, and the reaction time is about 1-6 hours.

The triassidization reaction of the present invention can be carried out subsequent to the urethanization reaction.

The trimerization catalyst used in the method of the present invention usually includes:
Any catalyst used in the triassidization reaction can be used, but tertiary amines are particularly preferred, such as triethylamine, N,N"-dimethylaniline, tributylatane, N-ethylpiperazine, and N.

Examples include N'-dimethylpiperazine, Mannich base of a phenolic compound, N,N',N'-)lis(dimethylaminopropyl)-hexahydro-syh-triazine, and the like. Among them, Mannich base of N, N", N"4 lis(dimethylaminopropyl)-hexahydro-5yh-) riazine or a phenol compound is preferred.

The amount of these trimerization catalysts used is 0.01 to 160% by weight based on the aromatic polyisocyanate as a raw material.

In the method of the present invention, the trimerization catalyst is added in portions. The number of additions may be in the range of 3 to 5 times.

If the number of times is less than 3, the remaining amount of colored and unreacted isocyanate components will increase, and if the number of times is 5 or more, no further effect will be obtained, which is disadvantageous in terms of operation.

The addition time is such that the first addition is made at the start of the triassidization reaction, and the final addition is made approximately 3 hours before the end of the reaction, and other additions are made at approximately equal intervals.

The reaction time may be 4 to 20 hours, and the reaction temperature may be -5 to 50°C, preferably 0 to 30°C.

Further, an antioxidant is added from the start of the reaction as a coloring inhibitor during the triassidization reaction. Examples of antioxidants include organic phosphorus compounds and phenolic compounds, with phosphorus antioxidants such as triphenyl phosphite and triethyl phosphite being particularly preferred. 0.05 to 1.0% by weight, based on the isocyanate, is preferred.

The triassociation reaction is usually carried out while analyzing the remaining NGO groups in the reaction mixture, and at a predetermined point, a known terminating agent is added to stop the triassociation reaction.

Examples of the reaction terminator include acids such as phosphoric acid, sulfuric acid, hydrochloric acid, acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, and benzenesulfonic acid, and acid chlorides such as hendiyl chloride and acetyl chloride. The amount used is preferably 1 to 3 times the equivalent to neutralize the tertiary amine.

The reaction is generally carried out by adding aromatic polyisocyanate, a color inhibitor, a diol, and an inert solvent to a reactor in which the reaction system can be sufficiently stirred, and carrying out the urethanization reaction under a nitrogen atmosphere.
Further, a trimerization catalyst is added in portions and the reaction is allowed to proceed until NC0% and unreacted diisocyanate reach a predetermined value.
At that point, a reaction terminator is added to stop the triassidization reaction.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example 1 81.0111 parts of a mixture of 99% by weight of 2.4-tolylene diisocyanate and 1% by weight of 2.6-tolylene diisocyanate, Phenyl phosphite 0.1
After collecting parts by weight, the inside of the reaction system was made into a nitrogen atmosphere and the temperature of the reaction solution was raised to 60°C. While stirring, the reaction solution was kept at 60°C, 19.0 parts by weight of 2,2.4-)limethyl-L3-bentanediol and 100 parts by weight of butyl acetate were added, and the reaction solution was heated to 80°C to form a urethane. The initial reaction time for the reaction was 4 hours, and the reaction solution was kept at 80'C for 3 hours, and the reaction was further carried out at 90°C for 1 hour.

After the urethanization reaction, the reaction solution was cooled to 10°C and heated with N.

1.5 parts by weight of 0.02 parts by weight of N',N"-)lis(dimethylaminopropyl)-hexahydro-5yh-triazine
The isocyanurate reaction was carried out by adding in three portions at intervals of time. The reaction time was 7 hours, and the reaction solution temperature was constantly maintained at 10°C. Finally, 0.08 parts by weight of orthophosphoric acid was added to complete the reaction.

Progress of the reaction was confirmed by measuring the decreasing NGO content and unreacted diisocyanate. The NGO content was determined by conventional titration analysis, and the unreacted diisocyanate was determined by gas chromatography.

The NC0% of the obtained product was 8.0% by weight, and the viscosity determined by a Brookfield rotational viscometer was 55 cps.
/25°C. As a result of analysis by gas chromatography, the unreacted TDI was 0.30 based on the resin solid content.
The weight % and hue were APHA standard solution No. 30 or less.

Example 2 The same reaction as in Example 1 was carried out using a mixture of 80% by weight of 2.4-1-lylene diisocyanate and 20% by weight of 2.6-)lylene diisocyanate and 81.0 parts by weight as the aromatic polyisocyanate. I did it.

The reaction time for isocyanuration was 8 hours. The analysis results of the obtained product showed that the NGO content was 8.0% by weight.
The viscosity determined by a Brookfield rotational viscometer was 57 cps/25°C. As a result of analysis by gas chromatography, unreacted TDI was 0.32% by weight based on the resin solid content, and the hue was 30 or less compared to the AI'HA standard solution.

Example 3 As the aromatic polyisocyanate, 81.0 parts by weight of a mixture of 65% by weight of 2.4-tolylene diisocyanate and 135% by weight of 2.6-tolylene diisocyanate was used. The reaction was carried out.

The reaction time for isocyanuration was 9 hours. The analysis results of the obtained product showed that the NGO content was 8.1% by weight, and the viscosity determined by a Brookfield rotational viscometer was 6.
It was 0 cps/25°C. As a result of analysis by gas chromatography, unreacted Tl11 was found to be 0.36% by weight based on the resin solid content, and the hue was below APFIA standard liquid Hiroshi 30.

Comparative Example 1 After collecting 81.0 parts by weight of a mixture of 99% by weight of 2.4-tolylene diisocyanate, 1% by weight of 2.6-)lylene diisocyanate, and 0.1 part by weight of triphenyl phosphite into a four-eye flask. The inside of the reaction system was made into a nitrogen atmosphere, and the temperature of the reaction solution was raised to 60°C. The reaction solution was heated to 60°C while stirring.
2,2,4-triphthylbentane-1,3-
1 part of diol (19.0 ft) and 100 parts by weight of butyl acetate were added, and the reaction solution was heated to 80°C to carry out a urethane reaction.

The reaction time was 4 hours, and the reaction solution was kept at 80'C for 3 hours.
The reaction was further carried out at 90"C for 1 hour.

After the urethanization reaction, the reaction solution was cooled to 100C and heated with N.

0.02 parts by weight of N',N''-tris(dimethylaminopropyl)-hexahydro-3yh-triazine was added to carry out an isocyanurate reaction.The reaction time was 5 hours, and the reaction solution temperature was kept at 10°C. Finally, 0.08 parts by weight of orthophosphoric acid was added to complete the reaction.

The analysis results of the obtained product showed that the NGO content was 8.1% by weight;
The viscosity determined by a Brookfield rotational viscometer was 75 cps/25°C. As a result of analysis by gas chromatography, unreacted TDr was found to be 0.49 times heavier than the resin solid content, and the hue was APH standard solution Nα50.

Comparative Example 2 A mixture of 80% by weight of 2.4-tolylene diisocyanate and 120% by weight of 2.6-tolylene diisocyanate was used as the aromatic polyisocyanate, except that the reaction time for isocyanuration was 6 hours. was carried out in the same manner as the comparative example.

The analysis results of the obtained product showed that the NGO content was 8.1% by weight;
The viscosity determined by a Brookfield rotational viscometer was 90 cps/25°C. As a result of analysis by gas chromatography, unreacted TDI was 0.54% by weight based on the resin solid content, and the hue was AI''I (A standard solution N[17
It was 0.

Comparative Example 3 As aromatic polyisocyanate, a mixture of 2.4-) lyresonoisocyanate 165% by weight and 2.6-) lyresonoisoneanate 35% by weight was used, and the reaction time for isocyanuration was 7. The same procedure as Comparative Example 1 was performed except that the time was changed.

The analysis results of the obtained product showed that the NGO content was 118.0% by weight.
The viscosity determined by a Brookfield rotational viscometer was 110 cps/25°C. As a result of analysis by gas chromatography, unreacted TDI was 0.55% by weight based on the resin solid content, and the color was 90% compared to the PHA standard solution. The physical properties, coating film properties, and compatibility of the aromatic isocyanurate compounds obtained in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1, Table 2, Table 3, and Table 4, respectively. .

(The following is a blank space) [Effects of the invention] As can be seen from Table-1, Table-2, Table-3, and Table-4,
In Examples 1 to 3, the coloration during the triassembly reaction was smaller than in Comparative Examples 1 to 3 (less unreacted diisocyanate was present. In addition, the compatibility with the polyol was good and the physical properties of the coating film were also excellent. There is.

Claims (1)

[Claims] In a method for producing a urethane prepolymer containing an isocyanurate group by subjecting an aromatic polyisocyanate and a diol to a urethanization reaction, and then performing a triassay reaction in the presence of a catalyst, the diol is contained in one molecule. A method for producing an aromatic polyisocyanurate, which is an aliphatic diol having two or more hydrocarbon substituents, characterized in that a catalyst is added in portions.