KR20000048790A - Isocyanate derivatives and their production - Google Patents

Abstract

PURPOSE: Blocked water-soluble isocyanate compounds are provided. CONSTITUTION: A method of forming bisulphite adducts of aliphatic isocyanates bears an aromatic moiety by mixing an aqueous solution of a bisulphite adduct forming agent with a solution of an isocyanate bearing an aromatic moiety in a substituted pyrrolidinone containing a catalytic amount of a substance which catalyses the bisulphite adduct forming reaction, the isocyanate being kept well dispersed so that the adduct is formed as a solution in the aqueous phase.

Description

Isocyanate Derivatives and Manufacturing Method Thereof {ISOCYANATE DERIVATIVES AND THEIR PRODUCTION}

The present invention relates to blocked water soluble isocyanate compounds.

Isocyanates have an important value in the treatment of plant fibers used as reinforcement materials in synthetic resin composites in that they react with the fiber surface in a way that enhances the waterproofness of the bonds formed between the fibers and the resin matrix. Moreover, the degree of denaturation of the fiber surface can be adjusted to make plant fibers as efficient as artificial fibers when used as a reinforcing material. In the early stages of this treatment, it is advantageous to be able to handle the isocyanate in a water-soluble manner which blocks the isocyanate group into a protecting group and then removes the protecting group when reaction with the fiber occurs. However, relatively high temperatures are required to remove the blocking groups of blocked isocyanates present. Furthermore, there is a disadvantage in that toxic solvents must be used to prepare and handle such blocked isocyanates.

Thus, for example, Guise (Aust. J. Chem. 2 S: 2583-2595 (1972)) describes the formation of blocked isocyanates in solvents in which aqueous 1,4-dioxane alone or mixed with other solvents, The coupling of isocyanates with sodium or potassium metabisulfite is described. The preparation of 1,6-nuxaethylene diisocyanate (HDI) in blocked form is described, wherein the isocyanate groups of this compound require a temperature of 167 ° C. to deblock.

Thus, according to the present invention, a solution of isocyanate containing an aromatic moiety in a substituted pyrrolidinone containing an aqueous solution of a nonsulphite adduct forming agent containing a catalytic amount of a substrate that promotes the non-sulphite adduct forming reaction By reaction with an aliphatic isocyanate containing an aromatic moiety to form a bisulfite adduct. The isocyanate must be well dispersed in order for the adduct to form as a solution in the aqueous phase.

As found, water-soluble blocked aliphatic isocyanates comprising aromatic moieties are reacted with an aqueous solution of adduct forming agent bisulfite by dissolving an isocyanate dissolved in substituted pyrrolidinone in the presence of a catalyst such as di-butyl tin chloride. It is based on the present invention that good yields can be obtained. The present method avoids the use of 1,4-dioxane, which is difficult to use on a large scale as a preventive measure to prevent the reaction with the solvents.

The blocked compound produced by the method can be deblocked at a lower temperature than the blocked HDI.

The solvent is preferably N-substituted pyrrolidinone, most preferably N-alkyl substituted pyrrolidinone, in particular N-alkyl substituted 2-pyrrolidinone. The most preferred solvent for use in the present invention is 1-methyl-2-pyrrolidinone (known as N-methyl pyrrolidinone).

The nonsulphite adduct forming agent is, for example, sulfite, hydrogen sulfite or metabisulfite, and may most preferably be present in the form of alkali metal salts. Preferred alkali metals are sodium and potassium. Preferably, the bisulfite adduct forming agent is sodium metabisulfite or potassium metabisulfite.

The catalyst can be, for example, an orgate compound, ie a dialkyl tin halide. Preferably the catalyst is dibutyl tin dichloride. Other catalysts that may be used include 1,4-diazobicyclo [2,2,2] octane (DABCO) as well as secondary and tertiary amines.

It has been found that the reaction is preferably carried out in the presence of triethanolamine which improves the yield of bisulfite addition products which are believed to act as co-solvents which introduce the isocyanates into the aqueous phase of the mixture. Other co-solvents can be used for this purpose.

The ratio of nonsulphite adduct forming agent and isocyanate used in the reaction is preferably (1-2): 1, such as the molar ratio of potential sulfite groups to isocyanate groups (i.e., the number of moles of potential sulfite groups used is Equivalent to, or somewhat more than, the number of moles of isocyanate groups).

The ratio of water and substituted pyrrolidinone should be such that precipitation of metabisulfite does not occur. Triethanolamine (or other amines known to catalyze) may be present in a proportion of up to 20% of the volume of the reaction mixture.

The catalyst is preferably present in an amount of up to 0.1% by weight of the total reaction mixture.

The amount of catalyst can be used to such an extent that the yield of blocked compound is not substantially reduced by the isocyanate reacting with the water present in preference to metabisulfite. In order to obtain satisfactory yields, the amount of catalyst used under certain circumstances may be determined by routine experimentation.

The reaction is preferably carried out within a range not exceeding 15 ° C. Satisfactory yields are obtained when the temperature is used at about 5 ° C. Lower temperatures may be used, but the reaction time can be longer without any benefit.

In order to carry out the process of the present invention, the isocyanate must be well dispersed so that the bisulfite adduct can be formed as a solution in the aqueous phase. Some conventional stirring methods can be used to achieve this object.

Isocyanates used in the process of the present invention include aliphatic moieties in which isocyanate groups are bonded and additionally comprise one or more aromatic moieties. The aliphatic groups to which isocyanate groups are bound may also be, for example, -CMe ₂ -which is bound to an aliphatic nucleus.

The method of the present invention is a water-soluble form of m- which can be used for the treatment of plant fibers such as jute, flax, hemp and linseed, in particular for improving the fiber performance of composite materials. It can be applied to the preparation of tetra-methylxylene di-isocyanate (TMXDI) and alpha-alpha-dimethyl meta-isopropenyl benzyl isocyanate (TMI). The fibers of this composite material can be, for example, phenol-formaldehyde fibers or urea (or urea-melamine) formaldehyde resins.

The present invention also includes blocked isocyanates which are bonded to the group of formula (1) or (2) below.

The blocked isocyanates of the present invention can be deblocked to release the isocyanate group or groups and reacted with the plant fibers by heating to 130 ° C. in the presence of the fiber. In the case of a pre-generated mat of plant fibers such as jute, the first processing method is to immerse the mat in an adduct of 25% w / w aqueous solution. The residual liquid is extracted, the treated mat is dried at about 70 degrees to have a water content of about 12%, and then pressurized and heated in a press until the temperature at which the blocking group is removed is reached. React freely with

The following examples do not limit the invention.

Example 1

The compound represented by formula (1) (blocked TMXDI) was prepared by the following method: Sodium metabisulfite (190 g) was dissolved in 530 g of water. The clear solution obtained was placed in a flask equipped with a stirrer and cooling means.

1-Methyl-2-pyrrolidinone (200 g) was added to the solution with 120 g of m-tetramethylxylene di-isocyanate, 3.5 g of triethanolamine and 0.1 g of dibutyl tin dichloride. While maintaining the mixture at 5 ° C., the reaction mixture was stirred continuously for 7 days, which resulted in one aqueous suspension. The mixture was filtered and the residue preferably contained blocked isocyanate and filtrate, after which it was evaporated and an excess of acetone was added to obtain an additional large amount of blocked isocyanate. The combined yield was 180 g of sodium salt of blocked isocyanate.

Example 2

The compound represented by formula (2) (blocked TMI) was prepared by the following method: Sodium metabisulfite (19 g) was dissolved in water (53 g) to form a clear solution. To the solution was added 1-methyl-2-pyrrolidinone (20 g), dimethyl-m-2-isopropenyl benzyl isocyanate (TMI; 9.4 g), triethanolamine (3.0 g) and 0.1 g dibutyl tin dichloride. It was. The mixture was stirred vigorously at 5 ° C. for 7 days, resulting in a cloudy suspension. The products were separated from the cloudy suspension using the same steps as described in Example 1, whereby a blocked dimethyl-m-isopropenyl benzyl isocyanate (10 g) of formula (2) was obtained.

Claims (20)

Non-sulphite adduct forming agent is mixed by mixing an isocyanate solution containing an aromatic moiety with an aqueous solution of a non-sulphite adduct forming agent in a substituted pyrrolidone containing a catalytic amount of a substance catalyzing the reaction of the bisulfite adduct formation. A method of producing a pit adduct, wherein the isocyanate continues to disperse well so that the adduct can be produced as a solution in the aqueous phase. The method of claim 1 wherein the solvent is N-substituted pyrrolidone. The method of claim 2 wherein the solvent is N-alkyl substituted pyrrolidone. The method of claim 3 wherein the solvent is N-methyl pyrrolidone. The process of claim 1, wherein the catalyst is an organotin compound. The process of claim 5 wherein the catalyst is a dialkyl tin halide. The process of claim 6 wherein the catalyst is dibutyl tin chloride. The process of claim 1, wherein the catalyst is DABCO. The process according to claim 1, wherein the process is carried out in the presence of triethanolamine. The method of claim 1, wherein the nonsulphite adduct forming agent is sulfite, hydrogen sulfite or metabisulfite. The method of claim 10 wherein the non-sulphite adduct forming agent is an alkali metal sulfite, hydrogen sulfite or metabisulfite. The method of claim 11, wherein the alkali metal is sodium or potassium. The method of claim 12, wherein the nonsulphite adduct forming agent is sodium metabisulfite or potassium metabisulfite. The process according to claim 1, wherein the isocyanate comprises an isocyanate group bonded to the aromatic moiety by a -CMe ₂ -group. The method of claim 14, wherein the isocyanate is TMI or TMXDI. The method according to any one of claims 1 to 15, wherein the molar ratio of the potential sulfite group and isocyanate group present is (1-2): 1. Blocked isocyanate comprising a group of formula (1) [Formula 1] Blocked isocyanate comprising a group of formula (2) [Formula 2] 18. The blocked isocyanate compound according to claim 16 or 17, which is an alkali metal salt. 20. The blocked isocyanate of claim 19 wherein the alkali metal is sodium or potassium.