JP2002241458A - Production method for isocyanurate-group-containing polyisocyanate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an isocyanurate-group-containing polyisocyanate which has a high NCO content, a low degree of coloration, a low viscosity, and very high qualities, does not substantially contain a high- mol.-wt. component, and can be widely used as a raw material for a curing agent used in polyurethane foam production and as a raw material for coating compositions, adhesives, elastomers, plastic foams, etc. SOLUTION: This method, for producing an isocyanurate-group-containing polyisocyanate from hexamethylene diisocyanate, is characterized in that 100 pts.wt. hexamethylene diisocyanate is subjected to a first step reaction at 55 deg.C or lower in the presence of 0.05-5 pts.wt. glycol having a secondary hydroxy group, 0.005-0.5 pt.wt. compound having a phenolic hydroxy group, and a catalytic amount of a fatty acid-alkali metal salt and then to a second step reaction at a temperature higher than in the first step reaction and the reaction is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing an isocyanurate group-containing polyisocyanate useful as a curing agent for polyurethane synthesis, a paint, etc. from hexamethylene diisocyanate (hereinafter abbreviated as HDI). An isocyanurate group that has an isocyanate group (NCO group) content, is free from coloring and turbidity, has a low viscosity, and is capable of efficiently producing a high-quality isocyanurate group-containing polyisocyanate substantially containing no high-molecular-weight substance. The present invention relates to a method for producing a polyisocyanate.

[0002]

2. Description of the Related Art
Many catalysts have been used for the isocyanurate polymerization of organic isocyanates, but these catalysts have a very high selectivity especially for aliphatic isocyanates and have a problem in effectiveness.
Isocyanurate polymerization of I was difficult, and practical application was difficult.

In recent years, as a method for producing an isocyanurate group-containing polymer by subjecting an HDI polyol adduct to isocyanurate polymerization of 60% by weight or less of all isocyanate groups, a molecular weight of 3,000 or less and a functionality of 2 to 3 have been proposed.
Using a polyol of the formula
A method is proposed in which 0.001 to 0.25% by weight and 0.5% by weight or less of a cocatalyst are used to cause an isocyanuration reaction at 100 ° C. or less, based on the polyol adduct. It is known that an HDI polymer containing an isocyanurate group and having a low NCO content and a high NCO content can be efficiently produced by preventing the occurrence of the above-mentioned problems (Japanese Patent Publication No. 35655/1988).

On the other hand, in recent years, low-viscosity isocyanurate group-containing polymers have been available without using a solvent.
Due to its excellent compatibility with various solvents, the demand for HDI-based curing agents for polyurethane synthesis, paints, etc. is increasing. Japanese Patent Publication No. 6-62913 discloses a low-viscosity isocyanurate group-containing compound. The polymer has a viscosity of 400 to 1600 cps at 25 ° C. in a state substantially free of an HDI monomer and a solvent, a uretdione dimer content of 10% or less, and an isocyanurate cyclic trimer of 60 to 95%. It is described that a polyisocyanurate-type polyisocyanate composition containing 0.1% by weight is freely compatible with low-polarity oil agents and polyols and is useful as an aliphatic polyisocyanate curing agent.

However, the isocyanurate-polymerization reaction of HDI has difficulties such as reaction control and selectivity of the catalyst. Particularly, in the case of low-viscosity isocyanurate-group-containing polymers, high-quality and high-purity polymers are efficiently produced. It is extremely difficult to produce well, and it is desired to develop a method for producing an isocyanurate group-containing polymer which is more industrially advantageous.

The present invention has been made in view of the above circumstances,
High NCO group content, little coloration and turbidity,
An object of the present invention is to provide a method for producing an isocyanurate group-containing polyisocyanate, which can industrially advantageously produce a high-quality isocyanurate group-containing polyisocyanate having a low viscosity and substantially no high molecular weight. .

[0007]

Means for Solving the Problems and Embodiments of the Invention As a result of diligent studies to achieve the above object, the present inventors have found that when producing an isocyanurate group-containing polyisocyanate from HDI, the HDI monomer is In the presence of a glycol having a secondary hydroxyl group as a co-catalyst, a compound having a phenolic hydroxyl group, and an alkali metal salt catalyst of a fatty acid, the first-stage reaction is performed at 55 ° C. or lower, By stopping the reaction after the two-step reaction, it has been found that an extremely high-quality isocyanurate group-containing polyisocyanate can be efficiently produced.

That is, according to the production method of the present invention, HDI
In the isocyanurate-forming reaction of the monomer, a co-catalyst derived from the above-mentioned compound having a glycol and a phenolic hydroxyl group is used. By adopting the two-step reaction, the isocyanurate-forming reaction can be efficiently performed in a short time with a small amount of catalyst while controlling the reaction, and it is possible to prevent turbidity and coloring of the reaction solution, and The by-product high molecular weight polymer is rapidly decomposed by the temperature rise at the end of the reaction, is substantially free of the high molecular weight material, has a low coloring degree, has a high NCO content, and has a very high quality isocyanurate group-containing polyisocyanate. Having a viscosity of 500 to 200 at 25 ° C.
Even a low-viscosity and high-quality material having a viscosity of about 0 mPa · s can be efficiently produced at a high yield.

Accordingly, the present invention relates to a method for producing an isocyanurate group-containing polyisocyanate from hexamethylene diisocyanate, comprising: adding 100 parts by weight of a hexamethylene diisocyanate monomer to 0.05 to 5 parts by weight of a glycol having a secondary hydroxyl group; In the presence of 0.005 to 0.5 parts by weight of a compound having a hydroxyl group and a catalytic amount of an alkali metal salt of a fatty acid, the first-stage reaction is performed at a temperature of 55 ° C. or lower, and then the first-stage reaction is performed at a higher temperature than the first-stage reaction. There is provided a method for producing an isocyanurate group-containing polyisocyanate, wherein the reaction is stopped after a two-step reaction.

Hereinafter, the present invention will be described in more detail. In the production method of the present invention, the HDI monomer is
Glycol having a secondary hydroxyl group, a compound having a phenolic hydroxyl group, and isocyanuration using an alkali metal salt catalyst of a fatty acid.

Here, glycol functions as a co-catalyst, and from the viewpoint of preventing the occurrence of turbidity or the like, glycol having two hydroxyl groups in one molecule and having a secondary hydroxyl group is used. Specifically as such a glycol,
1,3-butanediol (1,3-BG) and the like can be mentioned.

The amount of the glycol used is 0.05 to 5 parts by weight, especially 0.1 to 100 parts by weight of the HDI monomer.
When the amount is too small, the reaction does not proceed satisfactorily. When the amount is too large, it is difficult to obtain a resin having a low viscosity and a high NCO group content.

The compound having a phenolic hydroxyl group acts as a cocatalyst, and examples thereof include phenol, cresol, and trimethylphenol.

The amount of the compound having a phenolic hydroxyl group used is 0.0 to 100 parts by weight of the HDI monomer.
The amount is preferably from 0.5 to 0.5 part by weight, particularly preferably from 0.01 to 0.2 part by weight. If the amount is too small, the reaction does not proceed satisfactorily. If the amount is too large, it is colored with low viscosity and high NCO group content. Is difficult to obtain

The alkali metal salt of a fatty acid is used as a catalyst. Specifically, various alkali metal salts used for an isocyanuration catalyst can be used. Examples thereof include acetic acid, propionic acid, undecylic acid, capric acid, and the like. Octylic acid,
Examples thereof include alkali metal salts such as sodium salts and potassium salts of carboxylic acids such as myristylic acid.

The amount of the catalyst to be used can be appropriately adjusted in accordance with the activity of the catalyst, the amount of the co-catalyst, the reaction conditions and the like within the range of the usual amount of the catalyst. Since the compound having a phenolic hydroxyl group exhibits a high co-catalytic effect, it can be used in a relatively small amount, specifically, 0.0005 to 0.02 parts by weight, particularly 0 to 100 parts by weight of the HDI monomer. .001-0.
01 parts by weight. If the amount of the catalyst used is less than the above value, the reaction may not proceed, and if the amount is too large, the reaction solution may be turbid or colored.

In the production method of the present invention, the HDI monomer is subjected to the first stage reaction at a temperature of 55 ° C. or less in the presence of a glycol having a secondary hydroxyl group, a compound having a phenolic hydroxyl group, and an alkali metal salt catalyst of a fatty acid. rear,
The target isocyanurate group-containing polyisocyanate can be obtained by raising the temperature from the above temperature to perform the second stage reaction and terminating the reaction.

Here, the first stage reaction is carried out at a temperature of 55 ° C. or lower, preferably 0 to 55 ° C., more preferably 20 to 55 ° C. If the first stage reaction temperature is too high, coloring occurs strongly. If it is too low, the reaction does not proceed satisfactorily. The reaction time is preferably from 30 to 300 minutes, more preferably from 60 to 240 minutes. If the reaction time is too long, coloring may occur. If the reaction time is too short, control of the reaction may be difficult.

The second-stage reaction may be performed at a higher temperature than the first-stage reaction.
If the second stage reaction temperature is lower than the first reaction temperature, the by-product high molecular weight does not satisfactorily decompose, and the desired polyisocyanate cannot be obtained. May be. The reaction time is preferably 1
The reaction time is from 0 to 180 minutes, more preferably from 30 to 120 minutes. If the reaction time is too long, strong coloring may occur. If the reaction time is too short, decomposition of the high molecular weight compound may be incomplete.

The above isocyanuration reaction can be carried out in the presence or absence of a solvent. However, in the production method of the present invention, the reaction proceeds satisfactorily even in the absence of a solvent, and the desired compound is formed. Therefore, it is preferable to carry out the reaction in the absence of a solvent, whereby a post-process for removing the solvent can be omitted, and the process can be simplified.

When a solvent is used, the solvent is not particularly limited as long as it is inert to the isocyanate group and can dissolve the produced polymer, and all solvents generally usable for the urethane reaction can be used. Specific examples include acetates such as ethyl acetate, butyl acetate, and cellosolve acetate, and aromatic hydrocarbons such as toluene and xylene. The amount of the solvent used can be appropriately adjusted.

After the above-mentioned two-step reaction, the reaction is stopped.
While maintaining the reaction temperature of the second stage, adding a catalyst poison
It can be performed by stirring for about 0 to 120 minutes.

As the catalyst poison, generally used strong acids such as sulfuric acid and phosphoric acid can be used. The addition amount of the catalyst poison is an amount that can stop the isocyanuration reaction, and can be an appropriate amount according to the reaction conditions and the like.

After the reaction is stopped, catalyst poisons are removed as necessary, and remaining unreacted HDI monomer (F-HDI) is removed by a known method such as a thin film distillation method or a solvent extraction method. Thereby, the desired polyisocyanate containing an isocyanurate group can be obtained. In this case, it is desirable to remove the unreacted HDI monomer content in the polycisocyanate so as to be 1% by weight or less.

In the production method of the present invention, 2
A low-viscosity, high-quality isocyanurate group-containing polyisocyanate having a viscosity at 5 ° C. of 500 to 2000 mPa · s, particularly 500 to 1500 mPa · s, can be produced.

In the method of the present invention, the NCO group content of the isocyanurate group-containing polyisocyanate is adjusted to 2%.
The content can be adjusted to a high content of 1.5 to 24.5% by weight, particularly 22 to 24.5% by weight.

Further, according to the method of the present invention, JIS K
It is possible to obtain an isocyanurate group-containing polyisocyanate having a very low degree of coloration, having a number of colors of 60 or less, particularly about 40 or less by a 1556 measurement method.

Usually, the isocyanurate-forming reaction includes a 1-nylon structure in which isocyanate is polymerized in a chain form, and the 1-nylon structure tends to have a higher molecular weight than the polyisocyanurate, and is finally obtained. This increases the viscosity of the polyisocyanate. According to the present invention, the 1-nylon structure is rapidly decomposed in the second-stage reaction, so that it does not substantially contain such a high molecular weight substance, especially when its content is 1% by weight or less of the whole polyisocyanate. Certain isocyanurate group-containing polyisocyanates can be produced.

The isocyanurate group-containing polyisocyanate synthesized by the production method of the present invention is of an extremely high quality as described above, for example, a raw material such as a curing agent for polyurethane production, a paint, an adhesive, an elastomer, or a plastic foam. It can be used effectively as such.

[0030]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Examples and Comparative Examples] In a 500 ml glass four-necked flask equipped with a lid equipped with a thermometer and a stirrer, HD was added.
I, 1,3-BG, and phenol were charged in the amounts shown in Tables 1 to 3, potassium caprate was added in a specific amount under the initial reaction conditions shown in Tables 1 to 3, and reacted for a certain period of time. And further reacted for a certain period of time. afterwards,
The reaction was stopped by adding phosphoric acid and stirring for 1 hour.

Next, the obtained reaction solution was heated at 130 ° C. and 0.0
When thin-film distillation was performed under the conditions of 4 kPa, a bottom product having an F-HDI (unreacted free HDI) content shown in Tables 1 to 3 was obtained.

The amount of F-HDI was measured by gas chromatography. The number of colors and the state of formation of the high molecular weight substance were measured and evaluated by the following methods. The results are shown in Tables 1 to 3.

Number of colors (APHA): JIS K 1556
It was measured by a measuring method. Production state of high molecular weight product: The presence or absence of the high molecular weight product was measured and evaluated using gel permeation chromatography (GPC).

[0035]

[Table 1]

[0036]

[Table 2] * 1: Distillation was not performed because the reaction solution became cloudy.

[0037]

[Table 3] In the table, HDI: hexamethylene diisocyanate monomer, 1,3-BG: 1,3-butanediol, NPG:
Neopentyl glycol.

From the results shown in Tables 1 to 3, the effect of the cocatalyst is increased by reacting the HDI monomer with a glycol having a secondary hydroxyl group and a compound having a phenolic hydroxyl group, and the effect of the catalyst is reduced. The reaction solution was not turbid because the amount of catalyst was small.Moreover, by raising the temperature at the end of the reaction, the generated high-molecular-weight product was decomposed, and a low-viscosity product was obtained in high yield. (Example 1
~ 6).

On the other hand, when the glycol having a secondary hydroxyl group or the compound having a phenolic hydroxyl group is reacted alone with the HDI monomer, the reaction solution becomes cloudy due to the large amount of the catalyst (Comparative Examples 1 to 4). 4). Also, if the compounding amount of the glycol having a secondary hydroxyl group or the compound having a phenolic hydroxyl group is large, the viscosity becomes high, the NCO content becomes low, and the coloring degree becomes large (Comparative Example 5,
6) If the temperature is not raised at the end of the reaction, the viscosity increases due to the by-produced high molecular weight polymer (Comparative Example 7), and if the temperature is increased from the beginning of the reaction, the degree of coloring increases (Comparative Example 8). In the case of the above, it was also found that the isocyanurate group-containing polyisocyanate intended in the present invention could not be obtained.

[0040]

According to the production method of the present invention, a very high-quality isocyanurate group having a high NCO group content, a low degree of coloring, a low viscosity, and substantially free of a high molecular weight substance. Containing polyisocyanate can be efficiently produced, and the obtained isocyanurate group-containing polyisocyanate is
It can be widely used as a raw material for curing agents for polyurethane production, paints, adhesives, elastomers, plastic foams and the like.

Continued on the front page F term (reference) 4J034 AA04 HA01 HA07 HC03 JA01 JA06 JA32 KA01 KB03 KC02 KD01 KE02

Claims (3)

[Claims] 1. A method for producing an isocyanurate group-containing polyisocyanate from hexamethylene diisocyanate, comprising the steps of: adding 100 parts by weight of a hexamethylene diisocyanate monomer to a glycol 0.0 having a secondary hydroxyl group;
5 to 5 parts by weight of a compound having a phenolic hydroxyl group
After the first-stage reaction at a temperature of 55 ° C. or lower in the presence of 005 to 0.5 parts by weight and a catalytic amount of an alkali metal salt of a fatty acid, and then the second-stage reaction at a higher temperature than the first-stage reaction And producing the isocyanurate group-containing polyisocyanate. 2. The method according to claim 1, wherein the second stage reaction is carried out at a temperature of 60 ° C. or higher. 3. The method according to claim 1, wherein the reaction is carried out in the absence of a solvent.