JPS60255857A - Paint composition - Google Patents

Abstract

PURPOSE:To provide a paint compsn. which gives a coating film having good performance and excellent inter-laminar adhesion, by incorporating a specified modified amino resin. CONSTITUTION:A modified amino resin obtd. by co-condensing 0.1-30pts.wt. hydroxyl group-contg. compd. having a hydroxyl value of 5-500KOHmg/g and an MW of 100-8,000 (e.g. alkyd or polyester resin) with 100pts.wt. (on solid basis) amino resin (e.g. melamine or benzoguanamine resin) is used. Said modified resin is blended with an alkyd/melamine paint, an alkyd/benzoguanamine paint or an acrylic/benzoguanamine/epoxy paint to obtain a paint compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved coating composition, and more particularly to a coating composition comprising a specific modified amino resin and having particularly excellent interlayer adhesion.

Conventionally, when applying multiple coats of paint, or when repainting a defective painted area after applying a so-called top coat, it has been known that the difference between the first coat and the subsequent coat. Adhesion is poor (because of this, the paint film often peels off).

Therefore, in order to avoid and prevent such a situation of poor interlayer adhesion of the coating film, the following measures have been taken.

In other words, ■ A method of setting up a process for that purpose, such as wet-sanding the painted surface or wiping off defective painted areas with a hydrocarbon solvent such as petroleum benzene, ■ The mutual composition of both paints, especially the main ones, before repainting. A method of improving the vehicle resin itself, or a method of adding an additive such as a cationic surfactant to the paint that is first applied.

However, the above method ■ is generally manual;
This method simply increases the number of steps because no sufficient effect can be expected. In contrast, if method (2) is used, results will be obtained without adversely affecting the performance of other coating films.

However, as a result of intensive studies in view of the various drawbacks of the prior art as described above, the present inventors have found that a hydroxyl group-containing compound such as an alkyd resin or a polyester resin having a specific hydroxyl value and molecular weight and an amine resin can be combined. A coating composition containing a modified amino resin obtained by co-condensation at a specific ratio as a curing agent component or as an additive component prevents phase peeling without having any adverse effect on the performance of the coating film. The present invention was completed based on the discovery that the effect is remarkable.

That is, the present invention uses, as essential components, 100 parts by weight of amino acid in terms of solid content and 1 m of a hydroxyl group-containing compound having a hydroxyl value of 5 to 500 and a molecular weight of 100 to 8,000.
The object of the present invention is to provide a coating composition which is particularly excellent in interlayer adhesion of coating films, and which comprises a modified amino resin obtained by co-condensation with 0.1 to 60 parts by weight of BL.

Here, the above-mentioned modified amine resin is a known and commonly used amine resin such as melamine resin or benzoguanamine resin (al has a hydroxyl value of 5 to 500 KOH!/, 9.
Preferably 50 to 300 KOH/g and a molecular weight of 100 to 8,000, preferably 1.000 to 5.0
This refers to a compound obtained by co-condensing 11mbl of a hydroxyl group-containing compound 00, but alkyd resins, polyester resins, acrylic resins, epoxy resins, acrylic resins, etc. may also be used for such hydroxyl group-containing compounds. However, in view of interlayer adhesion, it is particularly preferable to use a compound having an ester bond in the main chain, such as an alkyd resin or a polyester resin, as K.

The modified amine resin surface is prepared by mixing the above-mentioned amine resin (a) with a hydroxyl group-containing compound vIXh) having an ester bond in the main chain, and then heating at 80 to 110°C.
Co-condensation can be carried out by keeping it warm.

At this time, co-condensation is carried out using the above-mentioned hydroxyl group-containing compound (bl as a solid content, usually 0.1 to 30 parts by weight, preferably 03 to 10 parts by weight) per 100 parts by weight of the solid content of the amino tree UIr (al). It is better to force it.

The modified amine resin thus obtained is used as a curing agent component or as an additive component, particularly for paints intended to improve the interlayer adhesion of the coating film.

Therefore, it is a target for improving glabella adhesion. Paints are generally of the type that forms a cured film by three-dimensional crosslinking with amino resins, and typical paints to which the above-mentioned modified amino resins are applied include alkyd resins. -Melamine paint, alkyd-benzoguanamine paint, alkyd-melamine-epoxy paint, alkyd-penzoguanamine-epoxy paint, oil-free alkyd-melamine paint, oil-free alkyd-benzoguanamine paint, acrylic-melamine paint Paint, acrylic - benzoguanamine paint, acrylic -
There are melamine-epoxy paints and acrylic-benzoguanamine-epoxy paints, but the modified amine resin in each of these paints may be used alone, or together with other general-purpose amine resins as a curing agent component, or Additive components may be used.

The coating composition of the present invention thus obtained can be used primarily as a baking paint for metal products, particularly as a top coating for automobiles.

Next, the present invention will be specifically explained with reference to Reference Examples, Examples, and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise specified.

Reference Example 1 [Hydroxyl group-containing compound (preparation example of BL)] Stirrer,
A four-eye flask equipped with a thermometer, a reflux condenser with a dehydration trap, and a nitrogen gas inlet tube was charged with 650 parts of coconut oil, 0.3 parts of lithium hydroxide, and 257 parts of trimethylolpropane, and heated to 250°C. After carrying out the transesterification reaction at a temperature of The temperature was gradually raised from 180°C to 220°C over 2 hours, and the dehydration reaction was further performed at 220°C for 6 hours. The result was a hydroxyl value of 110, an acid value of 11, and a number average molecular weight (Mn ) was obtained.

After that, this resin was adjusted with xylene so that the nonvolatile content (NY) was 60%, and the resulting N
The Gardner viscosity (the same applies hereinafter) of the alkyd resin solution containing 618% Y at 25° C. was UV.

Reference Example 2 (same as above) In a four-eye flask equipped with a stirrer, a thermometer, and a reflux condenser with a dehydration trap, 200 parts of isophthalic acid, 200 parts of phthalic anhydride, 237 parts of adipic acid, and 365 parts of neopentyl glycol were added. .3 parts and 124 parts of trimethylolpropane and an antifoaming agent were charged, the temperature was raised to 180°C while heating and stirring, and then the temperature was gradually raised from 180°C to 260°C over 5 hours. The temperature was maintained at 230°C until the acid value reached approximately 4, and when the acid value reached approximately 4, it was cooled while gradually adding 200 parts of xylene, and then 470 parts of butyl acetate was added to terminate the reaction. I forced it.

The resin solution obtained here is a polyester resin (NY: 598%, hydroxyl value: 54, and Mn: 3,000).
It was a solution of oil-free alkyd resin).

Reference Example 3 [Preparation example of amine resin] 126 parts (1 mole) of melamine was placed in a four-eye flask equipped with a stirrer, a thermometer, and a reflux condenser with a dehydration trap.
, 1873 parts (5 moles) of 80% rose formaldehyde
and 481 parts (65 mol) of n-butanol, the pH of the mixture was adjusted to 80 with a 10% aqueous sodium hydroxide solution, and then the mixture was heated at 80°C.
The temperature was raised to 100% to carry out the methylolation reaction for 30 minutes, and then phthalic anhydride was added to adjust the pH to 6.0.
Reflux dehydration was performed to 0'C, followed by vacuum distillation to remove the solvent.

Thereafter, it was diluted with a mixed solvent of xylene/n-butanol = 30/70° (weight ratio) to obtain a solution of melamine resin with a NY content of 59% and a viscosity of ST.

Reference Example 4 (Preparation Example of Modified Amino Resin) 400 parts of the melamine resin obtained in Reference Example 3 was placed in a four-eye flask equipped with a stirrer, a thermometer, and a reflux condenser.
A mixture of both resins with a viscosity of T was co-condensed at 100°C for 3 hours to obtain a solution of the target resin with a viscosity of V-W. Obtained.

Reference Example 5 (same as above) 400 parts of the melamine resin obtained in Reference Example 6 and 30 parts of the polyester resin obtained in Reference Example 2 were charged into a flask similar to Reference Example 4, and the viscosity was T. A mixture of both resins was co-condensed at 110° C. for 5 hours to obtain a desired resin having a viscosity of V.

Reference Example 6 (same as above) In a flask similar to Reference Example 4, 400 parts of the melamine resin obtained in Reference Example 6 and 15 parts of polypropylene gellicol having a molecular weight of 1000 were charged, and a flask with a viscosity of T was prepared. The mixture of raw materials was held at 100° C. for 6 hours to co-condense, and the desired resins with viscosities of U- and V were obtained.

Reference Example 7 [Amine resin (al preparation example)] 187 parts (1 mol) of benzoguanamine was placed in a flask similar to Example 2.
and 75 parts (2 moles) of 80% paraformaldehyde and n
After adjusting the pH of these mixtures to 57 with phthalic anhydride, the mixture was heated to 100'' CVC and dehydrated under reflux to 110°C.

After removing the solvent by distillation under reduced pressure, it is diluted with a mixed solvent of xylene/n-butanol-30/70 (weight ratio) to obtain a solution of benzoguanamine resin with NY of 505% and viscosity of A-A. I got it.

Reference Example 8 (Preparation Example of Modified Amine Resin) In a flask similar to Reference Example 4, 400 parts of the benzoguanamine resin obtained in Reference Example 7 and 166 parts of the alkyd resin obtained in Reference Example 1 were charged. A mixture of both resins having a viscosity of A was co-condensed at 100° C. for 5 hours to obtain a solution of the target resin having a viscosity of B-C.

Reference Example 9 (same as above) In a flask similar to Reference Example 4, 400 parts of the benzoguanamine resin obtained in Reference Example 7 and 153 parts of the polyester resin obtained in Reference Example 2 were charged, and a flask with a viscosity of A was prepared. The resin mixture was co-condensed at 100° C. for 5 hours to obtain a solution of the target resin having a viscosity of B.

Reference Example 10 (Preparation example of acrylic resin) First, 257 parts of styrene, 6 parts of methyl methacrylate
00 parts, 95 parts of l5o-butyl methacrylate, n-
150 parts of butyl acrylate, 50 parts of ethyl acrylate, 140 parts of β-hydroxyethyl methacrylate
A monomer mixture consisting of 8 parts of toluene and 8 parts of acrylic acid was prepared and placed in a four-eye flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube.
and 300 parts of butyl acetate, the temperature was raised to 115°C, and at the same temperature, 1.000 parts of the monomer mixture, 200 parts of butyl acetate, and 40 parts of jet-butyl peroctoate were added. , a mixture consisting of 20 parts of azobisin butyronitrile and 30 parts of di-tert-butyl peroxide was added dropwise over 5 hours, and after the addition was completed, the same temperature was maintained for 10 hours to obtain an NV of 5o,
3%, a hydroxyl value of 30, and a target resin solution with a Mn of Zoooo was obtained.

Examples 1 to 7 and Comparative Example 1.2 Various paint stock solutions were prepared according to the formulations shown in Table 1, and then xylene/1so-butanol-70
Ford cup rot 4 with a mixed solvent of 730 (volume ratio)
The mixture was diluted separately for 23 seconds, and then air-sprayed to a film thickness of 25 to 30 μm on a 0.8Q thick Bonderite-H44 treated steel plate with VC paint, and then heated to 140°C for 20 minutes. Baking was performed to obtain various coating films.

Table 2 summarizes the various performance comparisons made for each cured coating film.

2. /′ /’

Claims (1)

[Claims] As an essential component, in solid content ratio, (a) amino resin 1
and (b) 0.00 parts by weight of a hydroxyl group-containing compound having a hydroxyl value of 5 to 500 and a molecular weight of 100 to 8.000.
A coating composition comprising a modified amine resin obtained by co-condensing 1 to 30 parts by weight.