JPH081074A - Method for coating small part - Google Patents

Abstract

PURPOSE:To provide an efficient coating method for a small part in the laminated coating consisting of undercoating with solvent base paint and succeeding overcoating with water base paint while increasing the bonding strength between the laminated coating films and the strength of the coating film itself and improving the resistance of the overcoating film to dry cleaning. CONSTITUTION:In the overcoating with water base paint, the paint is dried and baked at temps. higher than the drying and baking temps. of a conventional water base paint where the quality of the product is not deteriorated, the baking time is controlled for 15-20min as in the conventional baking, and the drying and baking temps. are controlled at 170-195 deg.C which are much higher than the baking temp. of water base paint.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for coating small parts of a small number of multi-colored types that are often exposed to solvent treatment such as dry cleaning, and is excellent in coating strength and coating efficiency. Regarding the painting method.

[0002]

2. Description of the Related Art In recent years, the color demanded by customers has tended to diversify for small parts such as sliders for slide fasteners, stoppers, and eggplant rings that are attached to daily sundries such as clothes and bags. Therefore, it is necessary to prepare products to which various colors are applied in advance, and it is necessary to apply a small number of multicolor types in small quantities. Furthermore, in order to immediately respond to changing customer demands, it has become necessary to immediately deliver products.

Conventionally, the surface coating of these small parts has been carried out in a batch method by a rotary barrel coating method, and a solvent-based coating material containing an organic solvent has been used to carry out multi-layered coating. . This method is suitable for coating a large number of small color types that apply a large number of parts at a time, and with a small number of multiple color types, the number of parts to be processed in one operation is small, so the coating efficiency is high. Was extremely low. Further, in a parts painting system in which all the painting is done in a local main factory, the shipment of the product is far from the market, so it is impossible to immediately deliver the product in response to the customer's request. For this reason, it has been attempted to set up a branch factory near the market, paint the parts at the branch factory, and immediately deliver the product in response to the customer's request. However, in the case of coating with solvent-based paint containing organic solvent, which is generally used when painting parts, solvent vapor is generated in the paint drying process after painting, which not only leads to air pollution but also to many consumers. In particular, the generation of solvent vapors will become a major environmental problem in a market that has such problems.

Under these circumstances, attempts have been made to switch from solvent-based coating to water-based coating even in general coating. One of them is a coating method in which a water-based paint having poor coating film performance and a solvent-based paint having excellent coating film performance are laminated and coated to compensate each other for the disadvantages of the water-based paint and the solvent-based paint. In this case, there is a so-called wet-on-wet laminated coating that coats both the water-based paint and the solvent-based paint in an undried state during the laminated coating, and the wet-on disclosed in Japanese Patent Publication No. 5-87546. In wet laminated coating, a water-based paint containing water in a specific water-soluble or water-dispersible alkyd resin and an alkyd resin containing the same functional groups (hydroxyl group and carboxyl group) as the alkyd resin, the number average molecular weight of which is And the acid value is within a specific numerical range with respect to the number average molecular weight and the acid value of the alkyd resin used as an aqueous system, and a solvent-based paint containing an organic solvent is laminated and coated.

When wet-on-wet laminated coating is carried out using such a specific water-based paint and solvent-based paint, coating film cracks (coating film defects due to rapid evaporation and defoaming of the medium) and sagging ( It does not cause defects such as coating film defects that occur when the wet coating film drips due to gravity before drying, misalignment between laminated coating films, dents, bleeding, and blowing.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, for example, a slider for a slide fastener, an upper stopper, a lower stopper,
Alternatively, in the case of painting small parts such as buckles, as mentioned above, it is required to apply a small number of multi-colored types in small quantities and to immediately deliver products, so the final painting should be as close to the market as possible. In order to satisfy this, it is most preferable to use a water-based paint that does not lead to environmental pollution and is highly safe. On the other hand, from the viewpoint of coating film performance, laminated coating with a solvent-based paint is more advantageous than using a water-based paint alone. Then, in this case, the solvent-based paint is used as the undercoat and the water-based paint is used as the topcoat, which further meets the above-mentioned requirements.

[0007] In particular, the coated slider, the upper stopper, the lower stopper, etc. are attached to clothes and the like as slide fasteners, and although water-based paint is often used for dry cleaning. Originally, the coating film strength was weak and the dry cleaning resistance was still insufficient. Further, the inner wall surface of the slider is rubbed by the meshing element with each operation, the stopper collides with the slider body by opening and closing the slide fastener, and the pull tab is frequently grasped manually. Therefore, the coating film is gradually damaged, and the coating film is immediately peeled off particularly when the coating film is formed by an aqueous paint having a weak coating film strength.

By the way, in the wet-on-wet laminated coating method disclosed in the above-mentioned publication, the undercoating and the topcoating are not performed completely separately and are basically based on continuous coating. Although not suitable, even if this wet-on-wet laminated coating method is applied to the small parts as described above, the top coat film formed by the water-based paint is still easily peeled off by dry cleaning.
At the time of this peeling, in order to make the difference between the color of the top coat film and the color of the undercoat film of the peeling part inconspicuous, it is necessary to match both colors by all means. The development depends on the color of the undercoat and is limited to a few types. This can be said even when the undercoat of the solvent-based paint is completely dried and then the topcoat of the water-based paint is applied.Unless the strength and dry cleaning resistance of the coating film of the water-based paint are improved, the problem is solved. It is a task that is not done.

The present invention has been made in order to solve the above problems, and its purpose is to provide a bonding strength between laminated coating films and the coating film itself in a laminated coating in which an undercoating with a solvent-based coating material is followed by an overcoating with an aqueous coating material. Another object of the present invention is to provide an efficient coating method for small parts, which not only enhances the strength of the above, but also improves the dry cleaning resistance of the top coating film.

[0010]

The above objects are attained by:
Undercoating with a solvent-based paint containing an organic solvent on the surface of the component which is the main constitution of the present invention, after coating film drying is overcoated with an aqueous paint and dried and baked, in a coating method for forming a laminated coating film, The dry baking condition of the paint is set to a temperature higher than a normal dry baking temperature for the same water-based paint and within a range that does not cause deterioration of product quality, and the dry baking time is set to 15 minutes to 20 minutes. It is achieved by the method of painting small parts.

In particular, when the water-based paint is an aminoalkyd resin as the main forming element of the coating film, the dry baking temperature is 17
The temperature is preferably in the range of 0 ° C. to 195 ° C. Undercoat coating with the solvent-based paint is performed in the main factory, and topcoat coating is performed in the branch factory.

According to the coating method of the present invention, an undercoat is first applied with a solvent-based paint, the undercoat is dried, then an overcoat is applied with a water-based paint, and dry baking is performed. The dry baking temperature during the dry baking is in the range of 170 ° C to 195 ° C. More preferably, it is 175 ° C to 190 ° C. 170
At a temperature of not higher than 0 ° C, the top coat film and the under coat film are not sufficiently welded to each other, so that the top coat film peels off even in the cleaning resistance test. Further, when the temperature exceeds 195 ° C., the shape of the article to be coated, for example, the slider itself is deformed. It has also been found that the dry baking time at this time is important in improving the strength of the top coating film. That is, it is necessary that the dry baking time under the dry baking temperature is 10 minutes to 20 minutes.
This dry baking time is equal to or slightly shorter than the dry baking time in the case of coating with an ordinary water-based paint. When the dry baking time is 10 minutes or less, the water-based paint is not sufficiently dry baked and does not stick as a coating film, so that the strength of the coating film does not increase and the film is easily peeled off by dry cleaning. Further, if the drying temperature exceeds 20 minutes, it takes too much time to reduce the production efficiency for small parts.

Examples of the solvent-based paint used as the undercoat in the present invention include various acrylic resin paints, alkyd resin paints, aminoalkyd resin paints, epoxy resin paints and polyurethane resin paints. Further, as a solvent used for these solvent-based paints, it is necessary to select and prepare a solvent corresponding to each resin, but generally, a hydrocarbon solvent (toluene, xylene, chlorobenzene, monochloroethane, chloroethylene). , Monochloromethane, cyclohexane, normal hexane, etc.), alcohol solvents (methanol, isopropyl alcohol,
Butanol, etc.), ester solvents (methyl acetate, ethyl acetate, etc.), ether solvents (ethyl ether, etc.), ketone solvents (acetone, etc.), glycol ether solvents (methyl cellosolve, butyl cellosolve, etc.), alone or mixed. Can be used.

On the other hand, examples of the water-based paint used as the top coat of the present invention include water-soluble aminoalkyd resin paints and water-soluble acrylic resin paints. Usually, these paints are used in the form of an aqueous solution, but they may be used by being dispersed in water. Also, it may contain a slight amount of solvent.

In consideration of coating efficiency, it is preferable to employ a rotary barrel coating method for coating a large number of small parts at the same time for coating with a solvent-based paint. For coating with a water-based paint, an electrostatic coating method, an air spray method, The airless spray method is adopted.

According to the laminated coating method of the present invention,
Since it is possible to paint the undercoat and topcoat completely separately, at the main factory, the rotary barrel coating method is used to apply a large number of small colors of various undercoats using solvent-based paints Is distributed to multiple industries. At each branch factory, a small amount of multi-color type and a small amount of top coating is applied using a desired water-based paint in response to the customer's request. This method makes use of the advantage of coating efficiency in rotary barrel coating, and it is possible to respond to the customer's desired color by overcoating multiple colors of water-based paint. Enable immediate delivery. Further, environmental problems for the market can be easily prevented by using the water-based paint.

[0017]

EXAMPLE A typical example in which the present invention is applied to a metallic slider will be specifically described below. That is, first, the surface of the metal slider was undercoated by a rotating barrel type coating method using a thermosetting acrylic resin paint. The undercoating film is formed by dry-baking the paint adhering to the slider surface at a normal baking temperature. Then, the undercoating film surface was overcoated by an electrostatic coating method using a water-based paint of an aminoalkyd resin paint. This top-coat paint is applied at a normal baking temperature (140 ° C to 1
(50 ° C.) and dried and baked for a time equal to or slightly shorter than the normal baking time to form an overcoat film, and the degree of welding at the interface between the undercoat film and the overcoat film was observed. .

First, a slider for a slide fastener was undercoated with the solvent-based paint and overcoated with the water-based paint. The dry baking time between the undercoat and the topcoat is 20 minutes, and the dry baking temperature of the undercoat is 160 ° C., 1
Change to 70 ° C, 175 ° C, 180 ° C, 185 ° C, 190 ° C, and change the topcoat dry baking temperature to 160 ° C, 170 ° C, 175 for each undercoat dry baking temperature.
C., 180.degree. C., 185.degree. C., 190.degree. C. and 200.degree. C. were changed to dry baking. Table 1 shows JIS L 0821.
200m of tetrachlorethylene on the dyeing fastness tester
20 ml of the above-mentioned coated parts were put in a washing tester at 60 ° C. for 60 minutes, and the peeling result of the top coating film is shown. In the table, ○ indicates that peeling hardly occurs and the slider surface is in a good state, and × indicates that the coated surface peels off, or peeling does not occur but the slider deforms. It shows that it is in a state where it cannot be put to practical use because it has gone down.

[0019]

[Table 1]

It can be seen from Table 1 that the coating performance is low at the dry baking temperature of the conventional coating with the water-based paint and peels off from the surface of the slider in the dry cleaning resistance test. 195 ° C
It can be seen that the film strength that does not peel off from the slider surface can be obtained by carrying out in the temperature range of.

Moreover, the dry baking temperature in coating with the water-based paint is the same as the conventional dry baking temperature (140 ° C. to 150 ° C.).
Even at 170 ° C, which is far higher than (° C), it is shown that the dry cleaning resistance cannot be obtained because it is still not sufficiently welded at the interface between the topcoat film and the undercoat film. Since the slider material is (zinc alloy), the same dry baking temperature is 200 ℃
It was also found that the slider itself would be deformed if it exceeded. Of course, depending on the material of the slider, as long as the coating itself is not deteriorated due to overheating, good coating properties can be obtained even if dry baking is performed at high temperature.

Table 2 shows that a slider of the same type has a topcoat drying temperature of 180 ° C. and a drying time of 5 minutes and 10 minutes.
It shows the coating film strength when changed to minutes, 15 minutes, 20 minutes, and 25 minutes.

[0023]

[Table 2]

From Table 2, the dry baking time of the top coat is 15
It can be seen that when the time is set to -20 minutes, a top coating film made of a water-based paint having excellent coating film strength is obtained. In addition, when the drying time is 10 minutes or less, the dry baking of the water-based paint is not sufficient,
Since the film strength between the undercoating film and the undercoating film cannot be obtained and the film is not fixed as a coating film, it easily peels off by the dry cleaning resistance test. Further, if the drying temperature exceeds 20 minutes, the coating efficiency will be affected and the production efficiency will be reduced.

Table 3 shows the dry baking temperatures of 175 ° C and 18 ° C.
Three types of water-based paints made of different materials at different temperatures (0 ℃) (Kansai Paint Co., Ltd. "Asuka Bake" alone, Million Co. Ltd. "Comet" alone, "Asuka Bake" and "Comet" 1: 1 The coating performance is shown according to the type of water-based paint when dry baking is performed using a mixed paint).

[0026]

[Table 3]

From Table 3, it can be seen that the coating name "Comet" manufactured by Million Co., Ltd. has excellent dry cleaning resistance and a coating strength that does not allow the coating to peel off. here,
The compositions of "comet" and "asukabake" are generally as shown in Table 4, and the three compositions of "comet" and "asukabake" used in the above-mentioned examples had the same composition.

[0028]

[Table 4]

Table 5 shows that the same kind of slider is used, and the undercoating with the solvent-based paint is not carried out, and the dry baking temperature is 160 ° C., 170 ° C., 180 ° C., 190 ° C. Between the coated one and the undercoating using the solvent-based coating, and the top coating using the water-based coating at a baking temperature of 180 ° C.,
It shows the dry cleaning resistance. In addition,
The dry baking time was 20 minutes in all cases.

[0030]

[Table 5]

From Table 5, when undercoating with a solvent-based paint is not applied and only the water-based paint is applied to the slider surface and dry baking is performed at a higher temperature than the normal dry baking temperature, the water-based paint is used. Although the coating strength of is improved than before, when compared with the case of undercoating with a solvent-based paint, undercoating with a solvent-based paint is much more excellent in terms of dry cleaning resistance, It was found that the top coat did not peel off.

From the above results, after undercoating with a solvent-based paint, using a water-based paint, dry baking of the paint is performed at a temperature higher than the normal baking temperature and at a temperature range that does not deteriorate the material of the coated part. In addition, it has been found that a coated product having excellent dry cleaning resistance and not easily peeling the coating film can be obtained when the overcoating is performed by setting the drying time to be equal to or slightly shorter than the normal dry baking time. .

[0033]

As described above, according to the present invention, after the undercoat is dried with the solvent-based paint, the dry baking condition of the water-based paint is higher than the normal baking temperature, for example, 170 ° C.
In the temperature range of 195 ° C to 195 ° C, at the same time, a normal time or a time slightly shorter than usual, which is 15 to 20 minutes, is set,
By performing undercoating, a water-based paint coating with extremely excellent coating strength can be obtained, and peeling of the coating does not occur even after repeated dry cleaning, and high-quality coated parts with excellent appearance and durability can be obtained. . Further, by the method of the present invention, the strength of the overcoating film by the water-based coating material is significantly improved and the peeling strength is secured, so that the surface of the undercoating film is not exposed and the gap between the colors of the overcoating film and the undercoating film is prevented. Since it is not necessary to pay too much attention to matching, it becomes possible to select a wide range of colors for the topcoat film, using the color of the undercoat film as a basic color, and it becomes possible to easily deal with diversification of coloring for products.

Further, since the undercoating and the topcoating can be completely separated in the multilayer coating method of the present invention, the undercoating capable of coating a large number of the same color paint is conducted in the main factory in the region, and it is close to the large consumption city. At the branch factory installed in the area, it is possible to apply a top coat with a specific color of water-based paint in a small amount required by the customer, and as a result, it is possible to immediately respond to various customer needs. Not only that, but it can also be safely painted in factories where the environment is easily affected.

Claims (4)

[Claims] 1. A coating method for forming a laminated coating film by undercoating a surface of a component with a solvent-based coating material containing an organic solvent, drying the coating film, then top-coating with a water-based coating material and drying and baking. The baking conditions are set to a temperature higher than the normal dry baking temperature for the same water-based paint and within a range that does not cause product quality deterioration, and
A method for coating small parts, characterized in that the dry baking time is 15 to 20 minutes. 2. The dry baking temperature of the water-based paint is 170.
The coating method according to claim 1, wherein the coating temperature is from ℃ to 195 ℃. 3. The coating method according to claim 1, wherein the undercoat coating with the solvent-based paint is performed in a main factory and the top coating is performed in a branch factory. 4. The coating method according to claim 2, wherein the solvent-based paint comprises a thermosetting acrylic resin as a main coating film forming element, and the water-based paint comprises a water-based aminoalkyd resin as a main coating film forming element. .