JPS58171446A - Thermosetting resin composition - Google Patents

Abstract

PURPOSE:To prepare the titled resin composition giving a coating film having excellent smoothness, gloss and brightness, and sufficiently high hiding power and flexibility, and useful as a coating material, especially a powder coating material, by adding a specific amount of a silicon-containing polymer additive to the base resin. CONSTITUTION:100pts.wt. of a thermosetting resin such as polyester resin, vinyl polymer, epoxy resin, etc., is compounded with 0.01-10pts.wt., especially 0.1- 5pts.wt. of a silicon-containing polymer additive having a number-average molecular weight of >=500, preferably 1,000-100,000.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermosetting resin composition useful for paints and %KI & body paints.

It is already known that powder coating is used to coat metal surfaces with thermosetting resin compositions such as polyester, acrylic resin, and epoxy resin. In recent years, powder coatings have been widely used for decorative coatings, etc., but since such powder coatings do not use solvents, the resulting coatings tend to be inferior to solvent-based coatings in terms of appearance such as smoothness.

In particular, even with vinyl polymer paints, which have been in the spotlight in recent years for their excellent weather resistance, it is not possible to increase the pigment concentration due to poor pigment dispersibility. It had the disadvantage of being small.

As a result, when titanium oxide, for example, is used as a pigment, the pigment concentration required to obtain a smooth and glossy coating film is limited to 25% by weight.

In addition, PCM (
Pre-court method) has become a realistic requirement of the times, and an immediate solution is desired.

However, as a result of intensive research in view of the current situation as described above, the present inventors have found that by incorporating a specific amount of a specific polymer additive here, the excellent coating film properties inherent to the thermosetting resin are impaired. Furthermore, we have demonstrated that it is possible to obtain a coating material that has excellent smoothness, gloss, and sharpness, as well as sufficient hiding power and flexibility, without using powder coatings. The present invention was completed based on the discovery that the present invention can be maintained as is even in ordinary organic solvent solution-based, aqueous solution-based and dispersion-based paints.

That is, the present invention uses a thermosetting resin (thermosetting resin body) and a silicon-containing polymer additive (B) having a number average molecular weight of 500 or more as essential components, and the latter is added to 100 parts by weight of the former resin (4) component. The present invention provides a thermosetting resin composition comprising an additive (B) in a proportion of α01 to 10 parts by weight.

Here, as the thermosetting resin (4), known resins can be used as they are, and typical examples include polyester resins, vinyl polymer resins, and epoxy resin resins.

Polyester KM refers to polyesters obtained from polycarboxylic acids and polyhydric alcohols with a curing agent added, self-crosslinking and curing polyesters, and vinyl polymer systems. For example, a vinyl copolymer obtained from a vinyl monomer having a functional group such as a hydroxyl group, a carboxyl group, a glycidyl group, or an oxazolinyl group and another vinyl monomer is blended with a curing agent, or a butoxy resin. Vinyl copolymers having self-crosslinking functional groups such as methylamide groups, and vinyl copolymers of both types mentioned above modified with epoxy resins or polyesters, etc., are used. When the functional group of each copolymer is a hydroxyl group, an amino resin such as hexamethoxymethylmelamine or tetrabutoxybenzoguanamine or a block polyisocyanate is used as a curing agent for the resin. In the case of glycidyl groups, epoxy resins or polyoxazolines are used, and in the case of glycidyl groups, polyhydric carboxylic acids and polyhydric alcohols are used.

Further, examples of the epoxy resin type include those that combine a polyhydric epoxy compound such as a bisphenol type or an ester type with a curing agent such as Ami-7 or an acid.

On the other hand, the above-mentioned silicon-containing polymer additive (B) refers to one having a number average molecular weight of 500 or more obtained by copolymerization of a silicon-containing polymerizable monomer and another polymerizable monomer. Among these, typical silicon-containing polymerizable monomers include the following.

In addition, other typical polymerizable monomers include styrene, methyl (meth)acrylate, and ethyl (meth)acrylate.
Examples include acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, diethyl fumarate, dibutyl fumarate, acrylamide, acrylonitrile, (meth)acrylic acid or vinyl acetate.

That's true. If this molecular weight is lower than 500, it becomes impossible to increase the pigment concentration to provide sufficient gloss and smoothness of the coating film, which is one of the features of the present invention. This results in a significant decrease.

The composition of the present invention contains the polymer additive (B) in a ratio of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the resin (4). A)
, (B) are obtained by blending both components as essential components.

In this case, if the amount of the polymer additive (B) is less than 01 parts by weight and the blending ratio becomes small, the above-mentioned effect will inevitably occur.

On the other hand, if the blending ratio exceeds 10 parts by weight, the physical properties and stain resistance of the coating film will deteriorate, which is not preferable.

The thus obtained resin composition of the present invention can be used for paints,
It is particularly useful for powder coatings, and to prepare powder coatings from the composition of the present invention, pigments, fillers, additives, and other ingredients are added to the resin composition that has been melt-mixed in advance. Alternatively, a dry mixture of each of the resin (A), polymer additive (B), and other ingredients described above may be melt-mixed, cooled, and then pulverized. Any method may be used, such as a method in which the core resin composition and the other ingredients mentioned above are mixed in a solvent, and then treated with a spray dryer.

As a method for applying the powder coating, any known and commonly used method such as electrostatic coating or fluidized dip coating can be employed.

Of course, the composition of the present invention can also be used as a coating material such as a conventional organic solvent solution type, aqueous solution type, or dispersion type.

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

Reference Example 1 (Preparation example of silicon-containing polymer additive (B)) In a reactor equipped with a thermometer, a stirrer and a reflux condenser, 5
Add 0 parts of xylene and 50 parts of n-butyl acetate to 1
Heating to 25°C, a mixture consisting of 40 parts of styrene, 50 parts of n-butyl methacrylate, 10 parts of γ-methacryloxypropyltrimethoxysilane and 3 parts of azobisisobutyronitrile was added for 4 hours. The resulting solution was heated under reduced pressure (5W) and kept at the same temperature for 10 hours.
The number average molecular weight is 4000 after removing the solvent in H&).
A target additive was obtained. Below, this is referred to as a polymer additive (
It is abbreviated as B-1).

Reference Example 2 (Same as above) The same operation as Reference Example 1 was repeated except that K was used instead of γ-methacryloxyglobiltrimethoxysilane and the same amount of vinyltriethoxysilane was used to obtain a number average molecular weight of 5,500. A target additive was obtained.

Hereinafter, this will be abbreviated as a polymer additive (B-2).

Example 1.2 and Comparative Example 1.2 100 parts of xylene was added to the same reactor as in Reference Example 1 and heated to 125°C, and 40 parts of styrene, go part of glycidyl methacrylate, and 30 parts of xylene were added thereto. A mixture of isobutyl methacrylate, 4 parts azobisisobutyronitrile and 1 part t-butyl perbenzoate was added to 2
After adding it over a period of time and maintaining the same temperature VC for 10 hours,
The solvent was removed to obtain a resin having a softening point of 108° C. and a number average molecular weight of 5.000.

Then 15 parts of 1.10- to 85 parts of this resin
Comparative Example 1 was prepared by simply blending decanedicarboxylic acid, 1 part of "Modaflow" (a flow agent manufactured by Monsa, Inc., USA), and 43 parts of titanium oxide. The polymer additive obtained in Reference Example 1 or 2 (B
Two compositions of the present invention were obtained by adding 3 parts each of -1) or (B-2).

Comparative Example 2 was prepared by changing the amount of titanium oxide to 25 parts.

After that, regarding the obtained resin composition,
The mixture was kneaded at 100℃ using various extruders.
It was classified using a wire mesh with a mesh size of 0 to obtain a powder coating with a mesh size of less than the same mesh.

Next, each of these three paints was applied to a zinc phosphate-treated steel plate by electrostatic spray coating, and baked at 180°C for 20 minutes to obtain each coating film.

The performance test results for each coating film are summarized in Table 1.

Claims (1)

[Claims] l. As essential components, (4) thermosetting resin, and (B)
A silicon-containing polymer additive having a number average molecular weight of 500 or more is added to 100 parts by weight of the former resin, and the latter additive (
A thermosetting resin composition comprising B) in a proportion of Q, 01 to 10 parts by weight.