JPS60258270A - Powder coating composition for rugged pattern finishing - Google Patents

Abstract

PURPOSE:To produce the titled composition having excellent coating film properties and giving a dense and uniform coating film, by kneading a mixture containing a thermosetting resin and a thermoplastic cellulose ether resin as main components under a condition to melt only the former component, and cooling and finely pulverizing the mixture. CONSTITUTION:(A) 100pts.wt. of a thermosetting resin which is solid or powdery at normal temperature (e.g. epoxy resin) and (B) 0.01-0.7pt. of a thermoplastic cellulose ether resing (e.g. ethyl cellulose) are used as main components, and optionally compounded with a pigment, etc., and kneaded with an extruder. The kneaking is carried out at a temperature above the melting point of the component A and below that of the component B (60-130 deg.C). The kneaded mixture is cooled on a steel conveyor, roughly crushed, and finely pulverized to obtain the objective composition. USE:Metal coating, etc. of appliance, building material, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder coating composition that provides a textured finish on the surface of a coating film.

Powder coatings are widely used in general metal coatings due to their advantages in terms of being non-polluting and labor-saving.
There is a need for the development of powder coatings with special pattern finishes such as hammerton or even uneven pattern finishes.

Regarding the above-mentioned special pattern finishing in powder coatings, Japanese Patent Publication No. 48-7492 ``Powder coating compositions giving surface patterns'' has particle size distribution of 100 mesh or less and 250C.
A powder coating with a melt viscosity of 1000 voids or more and a particle size distribution of 100 horns or less at the following temperatures:
A powder coating having a melt viscosity of 100 poise or less at a temperature of 0C or less in a weight ratio of 0.5:10 to 10:0.
5 describes a powder coating that can be mixed to give a special pattern, and in Japanese Patent Publication No. 48-7686 ``Powder Coating for Pattern Finishing'', powder coatings with an average particle size of 200 mesh or less and 100 to 25
Powder paint with a melt viscosity of 100 poise or less at 0C and powder paint with an average particle size of 60 mesh or more and less than 200 mesh and a melt viscosity of 100 poise or less at 100 to 250C in a weight ratio of 0.5: 10. ~10
: Powder paints for pattern finishing mixed with 05 are described, but the pattern of the paint film obtained from these is non-uniform and has a so-called "apricot" shape, and a beautiful uniform uneven pattern cannot be obtained. do not have.

Furthermore, Japanese Patent Publication No. 51-47732 "Powder Coating Composition for Special Pattern Finishing" contains 100 parts by weight of a thermosetting resin that is solid or powdery at room temperature and 0.01 to 0.5 parts by weight of thermoplastic cellulose ester resin powder. A colored or uncolored powder coating composition for finishing a special pattern is described, but thermoplastic cellulose ester resin has poor alkali resistance and cannot be used for home appliances, which is the main application of powder coatings. Products and building materials have defects that make them unusable.

As a result of intensive research in order to obtain a powder coating composition for finishing an uneven pattern, the present inventors found that a thermosetting resin that is solid or powdery at room temperature and a thermoplastic cellulose ether resin are mixed at a certain mixing ratio so that the latter melts. The powder coating composition obtained by melting and kneading at a temperature that melts only the former, cooling and finely pulverizing the powder coating composition is satisfied with the uniform textured pattern finish.
Furthermore, it was discovered that cellulose ether resin improves the alkali resistance of the coating film, leading to the present invention.

That is, the present invention provides a mixture containing as main components 100 parts by weight of a thermosetting resin (component A) that is solid or powdery at room temperature and 0.01 to 0.7 parts by weight of a thermoplastic cellulose ester resin (component B). This relates to a powder coating composition for finishing an uneven pattern obtained by kneading, cooling, and pulverizing at a temperature where component A melts but component B does not melt.

Examples of the thermosetting resin (component A) that is solid or powdery at room temperature used in the present invention include epoxy-based, polyester-based, acrylic-based, and urethane-based resins, and thermoplastic cellulose ether resin (component B). ) It is necessary that component B does not melt when kneading with 60-1
] It is desirable to have a melting point of OC. Here, the epoxy resin has an epoxy equivalent of 450 to 1,000, for example.
It is a solid resin in the cylindrical part with a melting point of 60 to 110 C, and as a polyester resin, for example, a condensate of carboxylic acid capable of forming a polyester mainly composed of terephthalene and a polyhydric alcohol mainly composed of ethylene glycol. is solid at room temperature and has a weight average molecular weight of 1.
000-30000, acid value 20-200, melting point 60
~125C resin, and as an acrylic resin, for example, it is solid at room temperature and has a weight average molecular weight of 300 to 30,000.
, glycidyl equivalent is 200-1500, melting point is 60-1
．． 20 C resin, and as a urethane resin, for example, it is solid at room temperature and has a weight average molecular weight of] 0. , OO~
30000, melting point 60~105C1 hydroxyl value 10~
200 resin.

Further, the thermoplastic cellulose ether resin used in the present invention includes those in which part or all of the hydroxyl groups of cellulose are bonded with alcohol by dehydration, such as ethyl cellulose, methyl cellulose, and benzyl cellulose. The melting point is 13 because it does not melt in the bath when mixed with component A, and it is necessary to melt and obtain a uniform uneven pattern finish during baking hardening of the coating film.
It is desirable that it is 0-200C.

In the case of the above-mentioned crosstalk, the A component and the B component are 10 parts by weight.
It is necessary to mix at a ratio of 0:0.01 to 100:0.7, and when the B component is less than 0.0],
The concavo-convex pattern becomes unclear, and if it exceeds 07, the concavo-convex pattern is lost, resulting in an uneven orange-flask shape, which loses its design value.

In the present invention, various pigments, curing agents, fillers, flow control agents, etc. used in ordinary thermosetting powder coatings can be mixed as necessary.

Component A, component B, and various other components added as needed are uniformly mixed in a dry blender (C, then kneaded in an extruder). At this time, component A is melted and becomes component B. The mixture is kneaded at a temperature that does not melt (below 60 to 1 OC), cooled on a steel conveyor, coarsely pulverized, and then finely pulverized to a particle size distribution suitable for coating.

Painting methods include fluidized dipping, electrostatic current dipping, and electrostatic spraying, but electrostatic spraying is preferred, with a coating thickness of 3.
It is preferable to set it to 0-150 micrometers.

The baking curing conditions for the paint are at the temperature of the object to be coated]'70-25
1 to 30 minutes at 0C.

In order to obtain the coating composition according to the present invention, it is essential to knead at a temperature where component A melts but component B does not. (130C or higher), component B will be uniformly melted and dispersed with component A, and the uneven pattern will be lost.

The uneven pattern is caused by the two components A and B being incompatible with each other and having different melt viscosities and interfacial tensions. That is, during the curing process of the coating film, A
While the components undergo a curing reaction and the melt viscosity increases,
Since component B is a thermoplastic resin, it only melts and does not cause a curing reaction, so its melt viscosity becomes extremely small, and the difference in melt viscosity between component A and component B becomes significantly large. Since the molecular weight of component A increases due to the curing reaction, the compatibility with component B becomes poor, and the difference in interfacial tension increases, resulting in the formation of an uneven pattern.

The coating film obtained from the coating composition of the present invention has a uniform and beautiful dense uneven pattern and has excellent coating performance, making it industrially useful for use in metal products such as home appliances and building materials. It is something.

Next, the present invention will be explained in more detail by giving Examples, Comparative Examples, and Reference Examples. In the examples, parts are parts by weight.

Examples 1 to 4, Comparative Example 1 Based on the formulation shown in Table 1, all the ingredients were uniformly mixed for about 1 minute in a dry blender (Henschel mixer manufactured by Mitsui Miike ■), and then the ingredients shown in Table 1 were mixed uniformly for about 1 minute. The mixture was kneaded in an extrusion kneader (Pusconita PR-46 manufactured by Suss) under temperature conditions, and after cooling, it was pulverized in an impact pulverizer with a hammer set and passed through a 150-mesh sieve.

The obtained powder coating was applied to a steel plate with a thickness of 0.8 mm by powder spraying with a charge of 160 KV so that the film thickness was as shown in Table 1.
Baking was carried out under the baking conditions shown in Table 1.

The performance of the resulting coating film is shown in Table 2.

1・ Note: The unit in the formulation is parts.

Notes: 1) Epoxy resin, made by Yuka Shell Epoxy ■, Epikote 1004, melting point 95-105C2) Polyester resin A, made by Nippon Ester ■, Ester Resin ER-66,1
0, melting point 95-05C 3) Polyester resin B1 manufactured by Inu Nippon Ink Chemical Industry ■,
Finedic M-8550, θ point 115~]25
C 4) Acrylic resin, manufactured by Mitsui Toatsu Chemical ■, Aromatex P-6200, melting point 100-1] O5) Ethyl cellulose A1 manufactured by Dow Chemical Company, Ethocel 5TD7CPS, melting point 140-15C 6) Ethyl cellulose B1 manufactured by Dow Chemical Company, Ethocel 5TD45CPS, melting point 160-1CIC 7) Ethylcellulose C1 manufactured by Tau Chemical Co., Ethocel 5TDI 0OCPS1 melting point 170-80C 8) Cellulose acetate butyrate, cellulose ester 81 PM, manufactured by Eastman Chemical Prudential Co., EAB-531-1, melting point 130 ~150C 9) Glock isocyanate, manufactured by Hüls, Adduct B-1065 Reference example 1 In the formulation of Example 1, all components except ethyl cellulose A were made into a powder coating in the same manner as in Example], and then ethyl cellulose A was The powder paint obtained by dry mixing (mixing for 1 minute in a Henschel mixer) was painted and baked in the same manner as in Example 1, and the resulting paint film had unevenness and poor design. there were.

This occurs because ethylcellulose is not uniformly dispersed in the paint. ).

The coating film performance is shown in Table 2.

Reference Example 2 A powder coating was produced in the same manner as in Example 1, except that the melting cross-wire conditions were set to 140 to 145C, and then the coating film obtained by painting and baking had an uneven pattern. It was smooth and shaped like an orange, and had no design at all.

This is because the ethyl cellulose A melts during cross-contact and uniformly melts with the epoxy resin.

The coating film performance is shown in Table 2.

Reference Example 3 In the formulation of Example 3, ethyl cellulose A was added to 0.
The powder coating was produced in the same manner as in Example 1, except that the powder coating was applied to 0.009 parts, and then painted and baked. The resulting coating film had a slightly uneven feel, but did not have any design properties. .

The coating film performance is shown in Table 2.

Reference Example 4 A powder coating was produced in the same manner as in Example 1, except that 08 parts of ethyl cellulose A was used in the formulation of Example 1, and then painted and baked. The resulting coating film had an uneven pattern. It was smooth and shaped like an orange, and had no design at all.

The coating film performance is shown in Table 2.

Test method: Paint film appearance - Visual observation of uneven pattern Impact resistance - J I SK5400 (Depon type impact)
1/2"/, load 500y, height 5Q +9
No cracking or peeling Alkali resistance - No abnormality in the coating after immersion in 5% NaOH water, 2CI' for 240 hours As is clear from Table 2, Examples 1 to 4 are the same as Comparative Example 1.
It has superior alkali resistance compared to Reference Examples 1 to 4.
It can be seen that the appearance of the coating film is superior to that of the previous one.

Patent applicant: NOF Corporation

Claims (1)

[Claims] Thermosetting resin that is solid or powdery at room temperature (component A) 10
0 parts by weight and thermoplastic cellulose ether resin (component B)
A powder coating composition for finishing an uneven pattern obtained by kneading a mixture containing as a main component 0.001 to 0.7 parts by weight at a temperature where the A component melts but the B component does not melt, and then cools and pulverizes the mixture. thing.