JPS6015419A - Polyisocyanate resin composition - Google Patents

Abstract

PURPOSE:The titled composition suitable as a curing agent for a two-component urethane coating, comprising a polyisocyanate resin obtained by cyclizing tolylene diisocyanate and reacting the product with a polyalcohol. CONSTITUTION:Tolylene diisocyanate (TDI) and/or a reaction product between TDI and a diol (number-average MW of 60-500) are subjected to a reaction for forming isocyanurate rings at about 40-70 deg.C for about 4-10hr in the presence of a catalyst such as sodium methoxide. The obtained polyisocyanate (effective isocyanate group content of about 8-24wt%) is reacted with a polyalcohol of a number-average MW<=5,000 (e.g., castor oil or polyether polyol) under a condition including an NCO to OH equivalent ratio of about 4-15, a temperature of about 50-80 deg.C, and a reaction time of about 3-8hr with the aid of a catalyst such as dibutyltin dilaurate to obtain a polyisocyanate resin (effective isocyanato group content of about 8-20wt%).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyisocyanate resin composition, and more particularly to a polyisocyanate resin composition used as a curing agent for urethane paints, especially two-component urethane paints. be.

Two-component urethane paint is composed of a compound containing active hydrogen that reacts with isocyanate (generally, polyester polyol, oil-modified polyester polyol, acrylic polyol, etc.) and a polyisocyanate resin curing agent containing isocyanate groups. This polyisocyanate resin composition is mainly made by polymerizing tolylene diisocyanate (hereinafter referred to as TDI) to form an isocyanurate ring, or by adducting TDI to trimethylolpropane. It is used in

In particular, the former is often used when rapid drying is required. However, it has been recognized that the coating film of a two-component urethane paint using the above-mentioned polyisocyanate resin composition, particularly the former, has the drawback of whitening over time, and an improvement in this problem is desired.

Conventionally, in order to prevent the paint film from whitening over time, methods such as combining a two-component urethane paint with a polyisocyanate resin composition, adding plasticity to a polyol resin composition, and using stearic acid as a lubricant have been proposed. Various methods have been used to produce zinc, such as changing the method of producing zinc from a wet method to a dry method, and using plasticizers in paints. However, no method has been found to prevent whitening of the two-component urethane paint without sacrificing other basic properties of the paint and coating, such as drying properties and solvent resistance.

The present inventors have conducted intensive research to obtain a polyisocyanate resin composition for two-component urethane paints that does not whiten the coating film of two-component urethane paints without degrading the basic performance of the above-mentioned paints and coatings. , TDI or a polyisocyanate resin obtained by subjecting TDI and a diisocyanate from a limited diol to an incyanurate cyclization reaction to synthesize a polyisocyanate, and then reacting the polyisocyanate with a limited polyhydric alcohol. The present inventors have discovered that a composition consisting of the following does not reduce the basic performance of paints and coatings, and does not whiten coatings of two-component urethane paints, leading to the completion of the present invention.

That is, the present invention provides tolylene diisocyanate (A-1)
and/or tolylene diisocyanate and number average molecular weight 6
A polyisocyanate (A) obtained by subjecting a diisocyanate (A-2) obtained by reacting a diol having a molecular weight of 0 to 500 to an isocyanurate cyclization reaction with a polyhydric alcohol (B) having a number average molecular weight of 115,000 or less. Furthermore, it provides a polyisocyanate resin-containing curing agent that prevents whitening of the coating film of a two-component urethane paint. be.

The polyisocyanate resin composition of the present invention comprises a polyisocyanate portion obtained by performing an incyanurate cyclization reaction of TDI having a hard molecular structure or a diisocyanate made from TDI and a limited diol, and a molecule added thereto. Structurally, it is made up of limited polyol parts that are soft, and the hard part gives the paint film quick-drying properties, and the soft part suppresses minute cranks in the paint paste, that is, whitening, caused by the increase in internal stress of the paint film over time. Therefore, when the polyisocyanate resin composition of the present invention is used in two-component paints, the basic performance of paints and coatings, such as drying properties and solvent resistance, can be improved. It is thought that the whitening of the coating film over time will be improved without sacrificing the whitening of the coating film over time.

The diol having a number average molecular weight of 60 to 500 used in the present invention refers to the number average molecular weight of 1t60, which is generally commercially available.
It is possible to use diols that are 1 to 500, for example ethylene glycol, propylene glycol,
．． 3-butanediol, 1,4-butanediol, 1,
5-bentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, etc.
Furthermore, polypropylene glycol having a number average molecular weight of 500 or less, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A can be used alone or in combination.

Further, the reaction between TDI and the diol carried out in the present invention is carried out under reaction conditions of 40 to 70°C and 4 to 10 hours, and the ratio of the isocyanate equivalent of TDI to the equivalent of the limited diol is 2:1 or less. It will be held in and 40-70℃, 4-
The effective isocyanate group content of the polyisocyanate (A) obtained by the isocyanurate cyclization reaction under 10 hour reaction conditions is 8 to 24% by weight, particularly preferably 10 to 20% by weight based on the solid content. in weight. Catalysts used in this reaction include alkali metal alkoxides such as sodium methoxide and sodium ethoxide;
Quaternary ammoniums such as tetramethylammonium hydroxide and choline trimethyl-[2-hydroxyedyl]amsonium hydroxide are used.

The polyhydric alcohol (B) with a number average molecular weight of 5,000 or less used in the present invention refers to a compound having two or more active hydrogens involved in the reaction in the molecule, such as polyester alcohol/L/, Polyols such as castor oil, oil-modified polyester polyols, polyether polyols, polyε-caprolactone polyols, acrylic polyols, polyamines, polyamides, urea resins, and melamine resins, and generally commercially available polyhydric alcohols are used, such as, Ethylene glycol, propylene glycol, 1,3-butanediol, 1.4-butanediol, 1.5-bentanediol, 1.6-hexanediol, diethylene glycol, dipropylene glycol, trimethylolpropane, glycerin, pentaerythritol, alkanol Amine, bisphenol A
Ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc. are also used. Among these, castor oil and polyether polyol are preferred.

Particularly preferable number average molecular weights of these polyhydric alcohols are:
It is 400-1000. This reaction between polyhydric alcohol (B) and polyisocyanate (A) is carried out at an equivalent ratio of NGO
10H-4 to 15, at 50 to 80°C, for 3 to 8 hours.

The catalysts used at this time include dibutyltin dilaurate, stannas octo1ate, 1,8-diaza-bicyclo(5,4,O) undecene-7 phenol salt, N,
Examples include N-dimethylcyclohexylamine and triethylenediamine.

Further, the effective isocyanate group content of the polyisocyanate resin (C) obtained by reacting the polyhydric alcohol (B) specified in the present invention with the polyisocyanate (A) is 8 to 20% based on the solid content weight. % by weight, particularly preferably from 10 to
It is 20% by weight.

The resin composition of the present invention includes foams, flooring materials, molded products, waterproof materials, magnetic recording material binders, synthetic leathers, adhesives, anchoring agents,
It is used for paints, etc., and is particularly preferably used for paints.

In addition, when the polyisocyanate composition of the present invention is used as a two-component urethane paint, it is possible to use polyester polyols, oil-modified polyester polyols, acrylic polyols, polyether polyols, etc., which contain two or more active hydrogens that react with isocyanate. It is used in combination with polyols such as polyε-caprolactone polyol, polyamine, polyamide, and urea resin. In addition to active hydrogen-containing compounds, known additives such as colorants, extender pigments, cellulose, leveling agents, antifoaming agents, anti-sag agents, urethanization catalysts, organic solvents such as toluene, ethyl acetate,
Diluents, plasticizers, etc. such as methyl edyl ketone may be added.

In addition, the polyisocyanate resin composition of the present invention has a polyisocyanate resin used in other two-component urethane paints in order to maintain drying properties, solvent resistance, and whitening resistance.
This is advantageous because it is easier to adjust the curing speed and pot life when used together.

The above-mentioned polyisocyanate composition alone or a two-component urethane coating containing the same can be dried at room temperature or forced drying after being applied to the object to be coated.

The two-component urethane paint containing the resin composition of the present invention can be used everywhere, including woodworking, furniture, bridges, ships, land structures, tanks, and automobile repair, but is preferably used for woodworking,
Used for furniture and sanding sealer.

Examples will be explained below, and all parts in the examples are based on weight.

Example 1 400 parts of ethyl acetate, 300 parts of TDI, 1,8-diaza-bicyclo(5,4,0) undecene-7 phenol salt (hereinafter referred to as DBU phenol salt, Sanapo Nodo 61)
111) 3.00 parts of the product was placed in a clean reaction vessel free of moisture, stirred thoroughly, and reacted at a reaction temperature of 45°C for 5 hours. After that, add 13.00 parts of monochloro vinegar RI,
The isocyanurate ring-forming polymerization reaction is stopped.

Thereafter, 100 parts of castor oil was added, and the reaction was carried out at a reaction temperature of 60° C. for 4 hours with sufficient stirring to obtain a polyisocyanate resin (C-1).

Comparative Example I 11,044 parts of TD was charged into a clean reaction vessel free of water and thoroughly stirred, and 7,134 parts of trimethylolpropylene was melted and added dropwise at a reaction temperature of 70°C, followed by reaction for 3 hours.

Thereafter, the unreacted TDI raw material was separated from the polyisocyanate by a liquid-liquid exchange extraction method, and after removing the solvent, 650 parts of ethyl acetate was added to dilute the polyisocyanate.
A polyisocyanate resin (D-1) was obtained.

Its properties are: Non-volatile content: 75 parts 1% Viscosity (25℃, Gardner) V-Y effective isocyanate Content rate 12.5-13.5% Number of colors (Gardner) 2 or less Met.

Example 2 330 parts of ethyl acetate and 290 parts of TDI are charged into a clean, water-free reaction vessel, stirred thoroughly, and 10 parts of propylene glycol is added dropwise at a reaction temperature of 60'C, followed by reaction for 2 hours.

Thereafter, the temperature of the reaction vessel was lowered to 45°C, 290 parts of DBU phenol salt was charged, and the reaction was carried out for 4 hours. Thereafter, 2.90 parts of monochloroacetic acid was added to stop the isocyanurate ring-forming polymerization reaction.

Thereafter, 30 parts of polypropylene glycol with a number average molecular weight of 1i700 was added, and the reaction temperature was raised to 60°C while stirring thoroughly.
The reaction was carried out for 4 hours to obtain a polyisocyanate resin composition (C-2).

Comparative Example 2 450 parts of toluene, 300 parts of TDI, DBU7z/-7
L/3.00 parts of salt was placed in a clean reaction vessel free of water, thoroughly stirred, and the reaction was carried out at a reaction temperature of 45° C. for 5 hours.

Thereafter, 3.00 parts of monochloroacetic acid was added to stop the isocyanurate ring-forming polymerization reaction.

Then, 200 parts of ethyl acetate, 20 parts of methyl ethyl ketone
Add 0 parts to obtain a uniform resin solution. After that, vacuum distillation was performed to partially remove toluene and other solvents to obtain a polyisocyanate resin composition (D-2).

Its properties are: Non-volatile content: 50 parts 1% Viscosity (25℃, Gardner) U-X effective incyanate Content rate 7.0-8.0% Number of colors (Gardner) 3 or less Met.

Example 3 550 parts of ethyl acetate, 1400 parts of TD, and 4.00 parts of DBU phenol salt were charged into a clean reaction vessel without moisture.
The mixture is thoroughly stirred and the reaction is carried out at a reaction temperature of 45° C. for 5 hours. After that, 4.60 parts of monochloroacetic acid was added to stop the isocyanurate ring-forming polymerization reaction.
150 parts of 1000 polypropylene triol were charged, and the reaction was carried out at a reaction temperature of 60° C. for 4 hours with sufficient stirring to obtain a polyisocyanate resin composition (C-3).

Its properties are: Non-volatile content: 50 parts Viscosity (25℃, Gardner) G effective isocyanate Content rate 6.5% Number of colors (Gardner) 1 Deah no ko.

Example 4 550 parts of ethyl acetate and 470 parts of TDI were charged into a clean reaction vessel free of moisture, stirred thoroughly, and reacted at a reaction temperature of 60°C for 1 hour.
30 parts of 6-hexanediol was added dropwise and the reaction was carried out for 2 hours. Thereafter, the temperature of the reaction vessel was lowered to 45°C, 4.7 parts of DBU phenol salt was added, and the reaction was carried out for 4 hours. After that, 4.7 parts of monochloroacetic acid was added to stop the isocyanurate ring-forming polymerization reaction, and 5 parts of castor oil
The reaction was carried out at a reaction temperature of 60°C for 4 hours with sufficient stirring to obtain a polyisocyanate resin composition (C-4,
) was obtained.

Its properties are non-volatile content: 50% Viscosity (25℃, Gardner) F effective isocyanate Content rate 6.7% Number of colors (Gardner) l Met.

Reference Example 1 (Adjustment of curing agent) For 90 parts of polyisocyanate resin (C, -1),
10 parts of the polyisocyanate resin (D-1) of Comparative Example 1 were mixed to obtain a polyisocyanate resin composition (A) as a homogeneous solution.

Its properties are non-volatile content: 50% Viscosity (25℃, Gardner) E effective incyanate Content rate 7.0% Number of colors (Gardner) 1 Met.

Reference Example 2 (Adjustment of curing agent) 30 parts of the polyisocyanate resin (D-2) of Comparative Example 2 was mixed with 70 parts of the polyisocyanate resin (C-2) to form a homogeneous solution of polyisocyanate 1-1. 4I (fat composition (b)) was obtained.

Its properties are non-volatile content: 50% Viscosity (25℃, Power (donor) H effective incyanate Content rate 6.5% Number of colors (Gardner) 1 Met.

Application examples 1 to 4, Application comparative examples 1 to 2 (painting test) Reference example 1
Polyisocyanate resin composition (A) containing (C, -1) of Example 1 obtained in Example 1 as a main component, Example 2 obtained in Reference Example 2
A polyisocyanate resin composition (b) containing ((,-2) as a main component, a paint using polyisocyanate trees 1M (C-3) and (C-4) obtained in Example 3.4. Application Example 3.4 and paints using the polyisocyanate resin compositions (D-1) and (D-2) obtained in Comparative Example 1.2 were used as Application Comparative Example 1.2, respectively.
3Q8 (manufactured by Dainippon Ink & Chemicals @) was blended so that the isocyanate equivalent and hydroxyl equivalent were equal, and this was diluted with butyl acetate until the non-volatile content was 40%, and 70g/g was added to the cherry veneer. nf was applied, and the drying property and whitening property of the coating film were evaluated by cycle test (-20°C x 1 hour ← to 80°C x 1 hour).

The results and coating film physical property test results are shown in Table 1.

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Claims (1)

[Claims] A polyisocyanate (A) obtained by subjecting tolylene diisocyanate (A-1) and/or a diisocyanate (A-2) obtained by reacting tolylene diisocyanate with a diol having a number average molecular Ef of 60 to 500 to undergo an isocyanurate cyclization reaction; A polyisocyanate resin obtained by reacting a polyhydric alcohol (B) with a number average molecular weight of 5000 or less (
A polyisocyanate resin composition comprising C).