JPS6227411A - Coating resin composition - Google Patents

Abstract

PURPOSE:The titled composition which is excellent in pigment dispersibility and can give a paint excellent in storage stability and water resistance of a paint film, comprising an acrylic resin obtained by addition-polymerizing a specified ethylenically unsaturated compound with another copolymerizable, alpha,beta-ethylenically unsaturated compound. CONSTITUTION:0.1-20wt% ethylenically unsaturated compound of formula III (wherein R2 is a 1-8C alkylene, cyclohexane or phenylene) obtained by, for example, reacting a compound having an oxirane ring and a polymerizable double bond of formula I (wherein R1 is H or CH3) with an alkanolamine compound of formula II (wherein R3 is R1 or C2H5 and R4 is a 1-8C alkylene) is addition-polymerized with 99.9-80wt% another copolymerizable, alpha,beta- ethylenically unsaturated compound [e.g., 2-hydroxyethyl (meth)acrylate] to obtain the titled composition comprising a number-average MW of 1,000-20,000 and an OH value of 20-150 and being isocyanate-curable without adding any external catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a resin composition for coatings, and more particularly to a resin composition for coatings comprising a novel acrylic resin with particularly improved isocyanate curing reactivity.

Prior Art It is known that acrylic resins having hydroxyl groups etc. can be made three-dimensional by using an isocyanate crosslinking agent. In such reactions, basic compounds or organic tin compounds are usually added as external catalysts, but the reactivity is not sufficient, especially in the late stage of the reaction, the reactivity is extremely reduced, and the odor is large and the work environment is bad. Despite the above-mentioned problems and the strong desire to improve them, no satisfactory solution has yet been found.

The problem to be solved by the invention is an isocyanate-curing acrylic resin,
If we can obtain a resin that has increased reactivity with isocyanates, shows no decrease in reactivity even in the late stages of the reaction, and does not require an external catalyst, it will be extremely useful in the solid color and other paint industries. It is useful, and the present invention was made for the purpose of providing such a resin composition.

Means for Solving the Problems According to the present invention, the above object is achieved by the formula (where R is hydrogen or methyl; R2 is C1-C3 alkylene, cyclohexane or phenylene; R
3 is hydrogen, methyl group or ethyl group; R4 is C1-C
, alkylene group) and 99.9 to 80% of other copolymerizable α, β-ethylenically unsaturated compounds.
Number average molecular weight obtained by weight% addition polymerization of 1000~
20,000, and a coating resin composition comprising an acrylic resin having a hydroxyl value of 20 to 150.

The acrylic resin containing the compound represented by the above formula according to the present invention as a constituent monomer is composed of the ethylenically unsaturated compound having an alkanolamine moiety and other copolymerizable α, β
-Easily produced by conventional radical polymerization reactions with ethylenically unsaturated compounds. The compound represented by the above general formula used as a raw material is, for example, the reaction of a compound having an oxirane ring and a polymerizable unsaturated double bond such as R□ with an alkanolamine compound of the formula R□-NH-R4-OH, ■ Reaction of a carboxylic acid with a polymerizable unsaturated double bond such as CH2=C-C0OH and a hydroxyalkyleneimine compound, or a reactive derivative of a carboxylic acid with a polymerizable unsaturated double bond, such as an acid halogen compound and an alkanolamine. It is conveniently produced by reaction with a compound or the like.

In the acrylic resin according to the present invention, since the amino group exists near the hydroxyl group, the hydroxyl group can be activated, and the reactivity with the inocyanate group is increased, allowing reaction with the isocyanate group without using an external catalyst. It is characterized by easy progress. 1 to 8 alkylene carbon atoms are present between the amino nitrogen atom and the hydroxyl group, especially C1 to C
It has also been found that a range of G is preferred.

In addition, the present inventors have found that the hydroxyl group derived from the compound represented by the above formula not only has high reactivity with isocyanate, but also that no decrease in reactivity is observed even in the late stage of the reaction, and that the resin hydroxyl value is 20 to 150. It has been found that acrylic resins containing the above-mentioned compounds in an amount corresponding to 50 to 150, in particular, and having a molecular weight (number average) of 10 to 20,000 are particularly useful for coating purposes. However, in the acrylic resin of the present invention, as long as the hydroxyl group with increased reactivity derived from the compound represented by the above formula is present, for example, hydroxyl groups such as 2-hydroxyethyl (meth)acrylate may be added to other copolymerizable monomers. It is also possible to use monomers having the following.

The resin composition according to the present invention thus has a hydroxyl group that is highly reactive with incyanate groups, and is not only capable of isocyanate curing without adding an external catalyst, but also has pigment dispersibility and good properties due to the basic group. In particular, it has good dispersibility of acidic pigments and excellent storage stability of the paint, and since amino groups are incorporated into the resin, the water resistance of the paint film is also good.

The present invention will be explained below with reference to Examples. Parts and percentages are by weight unless otherwise specified.

Example 1 Synthesis of alkanolamine monomer (monomer A) MI
BK: 67.7 parts GMA: 142 parts Methylethanolamine: 61 parts MEHQ: 0.03 parts MIBK, MEHQ, and methylethanolamine are placed in a kolben and heated to 60° C. while blowing N2. 6
While maintaining the temperature at 0°C, GMA was added dropwise over 30 minutes, and after the addition was completed, the mixture was stirred for 30 minutes to complete the reaction.

Example 2 Varnish Synthesis Example (Table 1) A stirrer, a cooling tube, a N2 introduction tube, and a dropping funnel were attached to four Romalbens, and 80 parts of xylene was charged, and the temperature was raised to 120° C. and maintained. AlBN2 with the monomer composition shown in Table 1
．． 0 parts was dissolved and added dropwise over 3 hours. After aging for 30 minutes, t-butylperoxy 2-ethylhexanoate 0.5
A solution of 15 parts of xylene and 15 parts of xylene was added dropwise over 30 minutes, and the reaction was further maintained at 120° C. for 1 hour and 30 minutes to complete the reaction.

The following varnish was synthesized using the same equipment and method as in Comparative Example.

<Table 2> The above varnish was enamelized by a conventional method and Sumidur N
-75 (manufactured by Sumitomo Bayer) was mixed at an OH/NGO ratio of 1/1 and spray-painted on Bonde steel plate #411 coated with -0TO4811 gray (manufactured by Nippon Paint) intermediate coating. For Comparative Examples 3 and 4, an external catalyst was added and spray painted as shown in the table below. After baking at 60℃ for 30 minutes.

The appearance and hardness of the coating film were measured.

Paints using alkanolamines have excellent appearance, hardness, and weather resistance, but it is clear that the comparative examples do not give satisfactory results in terms of appearance, hardness, and weather resistance.

patent application agent

Claims (1)

[Claims] Formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R_1 is hydrogen or a methyl group; R_2 is C_1 ~
C_8 is alkylene, cyclohexane or phenylene group; R_3 is hydrogen, methyl group or ethyl group; R_
4 is a C_1 to C_8 alkylene group) and 0.1 to 20% by weight of the compound represented by C_1 to C_8 alkylene group, and 99.9 to 80% of other copolymerizable α,β-ethylenically unsaturated compounds.
Number average molecular weight obtained by weight% addition polymerization of 1000~
20,000, a paint resin composition comprising an acrylic resin having a hydroxyl value of 20 to 150.