JPS591757B2 - Huntai Toryouso Saibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to powder coating compositions, and more particularly to powder coating compositions comprising a thermosetting or thermoplastic resin and a compound that forms a stable chelate with the underlying metal.

Powder coatings do not contain volatile components such as solvents, so compared to solvent-based coatings, they improve the painting environment, prevent air pollution, and
It has many advantages such as reduced risk of fire outbreak.

Conventionally common powder coating compositions mainly contain thermosetting resins such as epoxy resins, polyester resins, and acrylic resins, or thermoplastic resins such as polyamide resins, polyethylene resins, and vinyl chloride resins. Contains a crosslinking agent, a pigment, a flow regulator and other additives,
Because of the above characteristics, it has become widely used for painting household electrical appliances, automobile bodies, etc.

However, conventionally, there has been a lack of powder coating compositions that form coating films that are corrosion resistant, weather resistant, and aesthetically pleasing.In particular, powder coating compositions that form coating films with excellent corrosion resistance regardless of the type of resin contained have been lacking. is eagerly awaited. An object of the present invention is to provide a powder coating composition that forms a coating film with excellent corrosion resistance.

In the powder coating composition according to the present invention, a powder coating comprising a thermosetting or thermoplastic resin has a stability constant of 0.1 to 20 parts by weight with the base metal per 100 parts by weight of the resin. It contains at least one selected from the group of five or more chelating agents and tannic acid.

The resins blended into the composition of the present invention include all resins commonly used for powder coatings.

Examples of such resins include thermosetting resins such as epoxy resins, polyester resins, and acrylic resins, and thermoplastic resins such as polyamide resins, polyethylene resins, and vinyl chloride resins. The powder coating composition of the present invention includes 0.1 to 20 parts by weight per 100 parts by weight of the resin,
Preferably 1 to 10 parts by weight of the base metal, e.g. Fe
, Zn, Cu, Al, etc., a chelating agent having a stability constant of 5 or more, preferably 10 or more, and tannic acid are blended.

In this specification, the term "stability constant" refers to the stability constant value l0gKMA measured at room temperature for an aqueous solution with an ionic strength of 0.1 (for example, "Metal Chelate" Nankodo (edited by Takeichi Sakaguchi and Keihei Ueno)). Suitable chelating agents used in the present invention include, for example, salicylic acid,
5-sulfosalicylic acid, Tyrone, N-methyliminodiacetic acid, methoxyethyliminodiacetic acid, methylthioethyliminodiacetic acid, aminoethyliminodiacetic acid, nitrilotriacetic acid, N-(0-hydroxycyclohexino(ha)ethylenediaminetriacetic acid, N') -Hydroxyethyl-ethylenediamine, N,N'monotriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminetetrapropionic acid,
Diethylenetriaminepentaacetic acid, phytic acid, ultra-condensed sodium phosphate (mix sodium hydroxide and phosphoric acid in a molar ratio of 1:2, add water to make a homogeneous substance, and then heat at 700°C for 10 minutes. (Prepared by heating for several minutes to perform dehydration and molecular dehydration, followed by rapid cooling).

The tannic acids used in the present invention include so-called tannins from China (quintuple tannins) and tannic acids from Turkey (gall tannins). Among these chelating agents, those having antirust properties (for example, tannic acid) are particularly effective.

The powder coating composition according to the present invention may contain 80% by weight or less of a pigment, if necessary. As the pigment, any of inorganic pigments such as titanium dioxide, iron oxide, chromium oxide, and carbon black, and organic pigments such as phthalocyanine, indanthrone, and quinacridone pigments can be used. In addition, the powder coating composition according to the present invention may contain appropriate amounts of additives, such as a leveling agent such as ModaFlo (manufactured by Monsanto Chemical Company), and a polishing agent such as polyethylene wax or fine silica powder. Disinfectant, Diacid 2
Anti-blocking agents such as 00 Bis (made by Nippon Hydrogen),
Antistatic agents such as catechol 86 can be included.

The powder coating composition according to the present invention can be prepared by dry mixing, for example, a thermosetting or thermoplastic resin, a chelating agent and/or tannic acid, and, if necessary, pigments and additives in a super mixer, pen shell mixer, etc. After that, install the extruder, the seal carburetor, the hot
It can be adjusted by melt-kneading with a hot roll or the like, cooling, then coarsely crushing with a crusher hammer mill or the like, and adjusting the particle size distribution with a sieve. In addition, chelating agents and/or
Alternatively, tannic acid can be mixed into the resin in advance. Coating and baking of this powder coating composition can be carried out under the same conditions as those commonly used for other general powder coating compositions.

In the powder coating composition of the present invention, the chelating agent and/or tannic acid incorporated into the composition interact with the base metal, which is the surface to be coated, to form a coating film with extremely excellent corrosion resistance.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the examples, "%" and "parts" all mean "% by weight" and "parts by weight." Example 1 Glycidyl methacrylate 15%, Methyl methacrylate 2
0%, isobutyl methacrylate 15%, styrene 40%
and 10% ethyl acrylate, 2% 2,2'-azobis(2-methylpropionitrile) as an initiator, and 1 t-dodecylmercaptan as a chain transfer agent.
% and copolymerized according to a conventional method, weight average molecular weight 3
Acrylic copolymer 1 with C 0,000 and secondary transition point 65
00 parts, 40.0 parts of rutile titanium oxide (RCR-3, pigment manufactured by BTP), 1.0 parts of ModaFlo (leveling agent manufactured by Monsanto Chemical), and 7.0 parts of adipic acid (crosslinking agent).
5 parts and 3.0 parts of salicylic acid (chelating agent) were mixed together in a super mixer, then melt-mixed in an extruder (temperature 80 C, passing time 2 minutes).
After cooling, the discharged product was coarsely crushed using a hammer mill, further finely crushed using a turbo mill, and finally passed through a 150-mesh sieve to obtain a product.

The particle size distribution of the product had a peak around 250 mesh, and more than 90% of the particles fell within the range of 150 to 325 mesh. After degreasing, the powder coating composition prepared above was applied to a SPC-1 steel plate test piece (0.8 mm x 50 mm x 150 mm) treated with zinc phosphate chemical conversion coating using a static coating gun (REP gun manufactured by Landsbirds). The coating was confirmed by spraying, and then heated for 20 minutes in a 200°C electric soaking hot air drying oven.

The coating thickness was 70±10 microns. Paint film performance is second
It was as shown in the table. Example 2-16 A powder coating composition was prepared in the same manner as in Example 1, except that 3.0 parts of each additive listed in Table 1 was blended instead of salicylic acid, and a coating film performance test was conducted. .

The results were as shown in Table 2. Note Test and evaluation method overview 1. Variation: Enofsen value (MlO2) by Erichsen tester. Impact resistance: Weight (1
/2"φ, 500g) and measure the height h (0ITL) when cracks occur on the painted surface 3. Gloss: JIS-K
-5400 to measure 60 degree specular reflectance (%) 4. Paint film skin: Visual judgment, ○ Practical for aesthetic purposes, × Not practical for aesthetic purposes 5. Corrosion resistance: (a) Salt water spray, JIS-K-5
400, spraying time 500 hours, 0500 hours, no abnormalities in peeling test after cross-cut section zero tape pressure bonding, x 2mm or more peeling on one side in the same peeling test, (b) Moisture resistance: 5'
C. Test time in an atmosphere of 100% relative humidity 240
Time, ○ No blistering, × Blistering, (c) Acid resistance: 5% hydrochloric acid, 1 month immersion in 2C, (d) Alkali resistance: 5% caustic soda aqueous solution, 1 month immersion at 20°C, ○ No abnormality, × Examples 17 to 20 with blistering Powder coating compositions were prepared in the same manner as in Example 1 according to the formulations shown in Table 3, and a coating film performance test was conducted.

The results were as shown in Table 6. Note 1) In the table, numbers indicate "parts", 2) Same as Example 1, 3) Epicote 1004 (manufactured by Ciel), 4) 67 parts of terephthalic acid, 17 parts of isophthalic acid, 52 parts of neopentyl glycol. Examples 21-24 of a polyester copolymer having an acid value of 5 and consisting of 7 parts of trimethylolpropane A powder coating composition was prepared in the same manner as in Example 1 according to the formulation shown in Table 4.

A coating film was formed in the same manner as in Example 1, and its performance was tested. The results are shown in Table 6. Comparative Example 1-4 A powder coating composition was prepared in the same manner as in Example 1 according to the formulation shown in Table 5.

Claims (1)

[Claims] 1. A thermosetting or thermoplastic resin, and 0.1 to 20 parts by weight per 100 parts by weight of the resin of at least one selected from the group of chelating agents having a stability constant of 5 or more with the base metal and tannic acid. A powder coating composition comprising: