JP2002248420A - Method for identifying coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily identifying the existence of the coating film or the information (kind, characteristics or history) on the coating film in a non-contact, simple method without damaging the coating film formed on the car body or parts of a car. SOLUTION: In the method for the presence of the coating film applied to the car body and parts of the car, the coating film, which is formed by coating at least a part of the car body and parts of the car with a paint preliminarily compounded with a fluoresent substance, is irradiated with ultraviolet rays or near ultraviolet rays to judge the presence of the coating film by the light emitted from the fluoresent substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the presence, type, characteristics, history, etc. of a coating film already formed on the body and parts of an automobile in a non-contact manner, preferably with the naked eye.

[0002]

2. Description of the Related Art Paints are applied on various articles for the purpose of protecting the surface and improving the commercial value. In general, undercoat films,
An intermediate coating film and a top coating film are sequentially formed and sold as commercial products. The reason why such three coating layers are formed is that it is necessary to impart as much performance as possible. For example, a cationic electrodeposition paint having high anticorrosion performance is used for the undercoating film. Further, the topcoat film includes a colored film for providing a high aesthetic appearance and a clear film for providing a color depth or shine formed thereon.

Recently, in addition to the above-mentioned required performance, there is a tendency to give higher performance to painting such as automobiles in order to increase added value. For example, by imparting hydrophilicity to the clear coating, it keeps lipophilic contaminants away,
Even if they adhere, a clear coating film having an antifouling function that can be easily washed away by rainwater or the like may be formed. However, since the clear coating film is transparent, it is difficult to visually distinguish such a clear coating film having an antifouling function from a clear coating film having a normal function.
In an actual automobile production line, one having a clear coating film of normal performance and one having a coating film having a special antifouling function flow in a mixed manner.

[0004] By the way, in the production line of automobiles, if dust adheres or stains due to contaminants, or a defect of the coating film itself, for example, crater, pinhole or foaming occurs, it is necessary to perform repair work. When selecting a paint for repair, it is necessary to check the history of the paint film (for example, whether it is a clear paint film having a normal function or a clear paint film having an antifouling function). As long as the functions can be classified by color like a colored coating film, it is difficult to distinguish a clear coating film as described above, which may hinder the selection of a paint.

[0005] It is possible to remove a part of the paint and analyze it by taking an infrared absorption spectrum or the like. However, not only the operation is complicated, but also the actual value of the paint is reduced due to the removal of the paint film. Not a target. In an actual production line, a number tag or the like is hung on a vehicle body and distinguished by a number or a symbol.However, there is a means to more easily and easily distinguish non-contact with information from the coating film itself. If it is present, it is possible to reduce discrimination errors and the like.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned conventional problems.
An object of the present invention is to provide a method for easily distinguishing a coating film by simple means without damaging the coating film and without actually touching the coating film. Here, discrimination of the coating film means not only visually recognizing the presence or absence and the type of the coating film, but also the history of each coating film in the laminated coating film (for example, whether the coating film is a hydrophilic coating film or a hydrophobic coating film). , Etc.).

[0007]

In order to solve the above-mentioned problems, the present inventors have found that paints used in painting processes for automobile bodies and parts, including paintings for repairing paint film defects, have been developed. By adding a fluorescent substance that does not emit under a light beam, but emits light when irradiated with ultraviolet or near-ultraviolet light, the coating film can be easily identified without contact under natural light or indoor light without giving an unnatural feeling to the coating film appearance. It was found that the presence or absence of a coating film could be confirmed with the naked eye by light emission by ultraviolet or near-ultraviolet irradiation. In addition, by using a fluorescent material having weak light resistance, the luminous ability is lost over time immediately after painting or after a certain period of time, and unnecessary light is not emitted even when irradiated with ultraviolet light or near ultraviolet light.
It was also found that it had no effect on the design of the completed or repaired automobile. That is, the present invention irradiates ultraviolet rays or near-ultraviolet rays to a coating film formed by coating a paint premixed with a fluorescent substance on at least a part of a vehicle body and parts of an automobile, thereby emitting light from the fluorescent substance. This is a method of determining the presence of a coating film and determining the coating film formed on the body and parts of an automobile.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention determines whether a coating has already been made (i.e., whether a clear coating has been applied to the body and parts of an automobile). Is particularly preferably applied when it is difficult to determine the presence or absence of According to the present invention, the presence of a coating film that has been difficult to determine can be easily determined by irradiation with ultraviolet or near-ultraviolet light, more preferably by the naked eye, by applying a fluorescent substance in advance to the paint and then applying the coating. Become.

In the present invention, the paint film to be determined is, for example, an outer layer portion (ie, a body portion including a vehicle body bottom portion) and an interior portion (inside a room, inside a trunk or a hood) of an automobile, and assembling them. Any of those formed on the surface of various components used for this purpose is included. In particular, as described above, the present invention can be effectively applied to a transparent clear coating film for overcoating, which was difficult or impossible to determine by the conventional method. INDUSTRIAL APPLICABILITY The present invention can be applied not only to a production line but also to a non-production line as long as it is a step of coating an automobile body and parts (including coating for repairing a defect on a coating film surface).

[0010] In the method of the present invention, first, a fluorescent substance is previously blended into a paint used for forming a coating film. The paint to be mixed with the fluorescent substance is not particularly limited, but a clear paint, particularly preferably a clear paint for top coat, is used. This is because the function needs to be determined because the outermost clear coating film is the largest. The clear paint includes a slightly colored one and a colorless and transparent clear paint having no coloring pigment.
As paints and pigments used at the time of fine coloring, pigments having good weather resistance used in solid paint base coat paints, particularly inorganic pigments, organic red pigments, inorganic yellow pigments,
Organic yellow pigments and brighteners are exemplified. Specifically, titanium oxide, carbon black, phthalocyanine blue,
Examples include sllen blue, phthalocyanine green, aluminum flake, and mica flake.

Further, the clear paint is a film-forming resin,
Those containing a curing agent and, if necessary, a coloring agent and additives are generally used. Functions imparted to the clear coating film are hydrophilic,
Examples include hydrophobicity, scratch resistance, chemical resistance, and stain resistance. Generally, a clear hydrophilic film and a clear hydrophobic film will be described.

As described above, the hydrophilic clear coating film does not attract lipophilic stains, and has a predetermined amount of a hydrophilic functional group such as an acid-absorbing group or a carboxyl group on the coating film surface. It may have a predetermined amount of a functional group that is hydrolyzed by moisture in the air to give a hydrophilic functional group, for example, an alkoxysilyl group. The hydrophilic functional group or the functional group that is hydrolyzed to give a hydrophilic functional group may be one bonded to the polymer skeleton of the film-forming resin or one derived from a component mixed in the coating composition. As the hydrophilic clear coating film, for example, JP-A-2000-17850
No. 1, JP-A-2000-204312, JP-A-10-140077, and the like.

On the other hand, the hydrophobic clear coating film refers to a coating film whose surface has poor wettability with water (ie, has water repellency). When a water droplet is dropped on the surface of the hydrophobic coating film, the contact angle of the water with the coating film exceeds 70 degrees. As the hydrophobic clear coating film, for example, JP-A-2-45577
JP, JP-A-3-287650, JP-A-4-3
No. 63374 or JP-A-8-259667.

The film-forming resin of the clear paint is not particularly limited, and acrylic resins, polyester resins, epoxy resins, urethane resins and the like can be used. These resins include amino resins and / or block isocyanate resins. Used in combination with a curing agent. For example, a combination of an acrylic resin and / or a polyester resin and an amino resin, or a combination of an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system, from the viewpoint of transparency or acid etching resistance.

In addition to such various clear paints, the present invention, if necessary, is a paint that is usually used for painting the body and parts of automobiles and for repairing coating film defects. Undercoating and intermediate coatings to enhance the adhesion between certain steel materials and the overcoating film formed in the subsequent coating process and to provide anticorrosion and hiding properties, solid, pastel or A fluorescent substance may be blended into a top-coat color base paint capable of expressing a metallic color, or a repair-only paint for repairing coating film defects / defects, but if the paint is colored, its hue is It is particularly desirable that the color is not the same as the color of the light emitted by the fluorescent substance due to ultraviolet light or near ultraviolet light irradiated for the determination.

In the present invention, most effectively, a colorless and transparent clear paint is mixed with a fluorescent substance.

The fluorescent substance to be incorporated into the paint may be any substance that emits light having a wavelength close to visible light in addition to heat radiation when it is irradiated with ultraviolet light or near ultraviolet light. Examples thereof include diaminostilbene, uranine, and the like. Organic fluorescent dyes such as thioflavin, eosin, rhodamine B; or white under ordinary room light such as natural light or white fluorescent light, and when exposed to ultraviolet light such as black light or near ultraviolet light. Inorganic phosphorescent pigments that emit light, so-called fluorescent pigments [for example, ZnS / Ag (blue), (Zn, Cd)
S: Cu (green yellow), (Zn, Cd) S: Ag (yellow green), ZnO: Zn (white green), ZnS: Cu (green), Y ₂ O ₂ S: Eu (red), ZnS: Cu + Zn
₂ SiO ₄ : Mn (green), Cd ₂ O ₂ S: Tb (yellow green), ZnS: Cd, Al (yellow green), Y ₂ O ₂ S: T
b (yellow green), ZnS: Ag, Ga, Al (blue), etc.]
Can be used.

In the present invention, the fluorescent substance selected from the above is blended in the paint in such an amount that it is invisible to the naked eye under visible light, usually less than 1% based on the resin solid content in the paint. However, the amount of the fluorescent substance can be increased to about 10% with respect to the resin solid content in the coating material in some cases.

A paint containing a fluorescent substance in advance (hereinafter referred to as a fluorescent substance-containing paint) is applied to at least a part of the body and parts of an automobile and, if necessary, the entire surface thereof, and can be distinguished by the present invention. Form a coating. In the method of the present invention, any commonly used coating method can be used, and examples thereof include, in addition to brush coating and spray coating, imprinting specific characters and figures such as stamps. Painting can be manual or automated by machine. The application of the fluorescent substance-containing paint to a part of the vehicle body and parts of the automobile can be performed by, for example, stamping or spraying or brushing using a template as described above.

Irradiation of ultraviolet or near-ultraviolet light to a coating film formed on the body and parts of an automobile is performed using a simple ultraviolet or near-ultraviolet irradiation device, for example, a black light (wavelength: about 300 to 450 nm). By this irradiation, light is emitted from the coating film containing the fluorescent substance, and the coating film can be distinguished by detecting the light with a sensor or the like, or more preferably by visually recognizing it with the naked eye.

Irradiation with ultraviolet or near-ultraviolet light can be performed immediately after applying the fluorescent substance-containing paint (that is, an uncured coating film), after setting for a certain period of time, or after drying and curing the coating film. Can be performed on a coating film in an arbitrary state after a predetermined period has passed from the completion of curing of the composition.

When a coating film formed from a fluorescent substance-containing paint is irradiated with ultraviolet or near-ultraviolet light, light is emitted from the fluorescent substance even during irradiation with ultraviolet or near-ultraviolet light (fluorescence). It may be maintained even after the UV or near UV irradiation is stopped (phosphorescence). However, in the case of emitting phosphorescence, the emission of light must have already been completed at the completion of automobile production or at the completion of repair of defects on the coating surface, in order not to impair the design of the coating. desirable.

More preferably, in the case of a paint applied to the outer layer of an automobile body or a component attached thereto,
In order not to impair the aesthetic appearance of the automobile, a fluorescent substance having lower light resistance is selected and blended. In this case, light emission due to irradiation of ultraviolet light or near ultraviolet light can be confirmed with the naked eye or using a light receiving element such as an optical sensor depending on the intensity.

By increasing the amount of the fluorescent substance, the intensity of the fluorescent or phosphorescent light emitted from the coating film can be increased, and the light storage time can be prolonged. In particular, phosphorescence is useful when inspecting an object to be coated having a coating film, repairing a defect on the coating film surface, or attaching a component to a predetermined portion. If necessary, use a paint prepared by selecting and blending a fluorescent material with excellent light resistance, or use a paint site that is hardly exposed to light (for example, the interior of an automobile,
By coating the fluorescent substance-containing paint on the inside of the trunk or the hood, etc., the deterioration of the fluorescent substance is also delayed or suppressed, so that the time for determining the coating film can be further extended.

In the present invention, paints having different types and amounts of fluorescent substances are used to change the emission intensity and color of fluorescent or phosphorescent light when irradiated with ultraviolet or near-ultraviolet light, or paints containing a fluorescent substance are specified. By painting in the shape of letters or figures and expressing the shape of fluorescence or phosphorescence in the form of letters or figures, not only the presence or absence of a coating,
It is also possible to identify information such as type, properties and history of the coating (hydrophobic or hydrophilic).

[0026]

EXAMPLES The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples. As used herein, “parts” and “%” are based on weight unless otherwise specified.

Production Example 1 Here, a method for preparing a hydrophilic clear coating composition will be described. (1) Synthesis of half-ester acid group-containing acrylic copolymer In a 3 L reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, a nitrogen introduction pipe, and a dropping funnel, 330 parts of xylene and 110 parts of propylene glycol monomethyl ether acetate were added. Was heated to 127 ° C. Using a dropping funnel, 300 parts of styrene, 360 parts of 2-ethylhexyl methacrylate, 112 parts of isobutyl acrylate, 26 parts of acrylic acid, 202 parts of maleic anhydride, 300 parts of propylene glycol monomethyl ether acetate, and 300 parts of t- Butyl peroxy-2-ethylhexanoate 90
And a solution consisting of 100 parts of xylene was added dropwise over 3 hours.

After maintaining at 127 ° C. for 30 minutes after the completion of the dropwise addition, a solution comprising 10 parts of t-butylperoxy-2-ethylhexanoate and 50 parts of xylene was added dropwise over 30 minutes. After the completion of the dropwise addition, 127 ° C. for another hour.
The reaction was continued to obtain a varnish containing 53% of nonvolatile matter containing acrylic polyanhydride having a number average molecular weight (Mn) of 3000.

To 1990 parts of the obtained varnish, 100 parts of methanol was added, and the mixture was reacted at 70 ° C. for 23 hours.
A varnish containing 7 mg KOH / g (in terms of solid content) of a half ester acid group-containing acrylic copolymer was obtained. The half-ester acid group-containing acrylic copolymer was measured for its infrared absorption spectrum to determine the absorption of acid anhydride groups (1785).
cm ^-1 ) was confirmed to have disappeared.

(2) Synthesis of carboxyl group-containing polyester resin In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, a nitrogen introduction pipe, a water separator and a rectification tower, 136 parts of pentol, 456 parts of ε-caprolactone and 0.1 part of dibutyltin oxide was charged, heated to 170 ° C., and kept at 170 ° C. for 3 hours.

Thereafter, 539 parts of phthalic anhydride with hexahydric acid dissolved by heating were added, and the mixture was kept at 150 ° C. for 1 hour. Then, 464 parts of ethyl 3-hydroxypropionate was added.
Number average molecular weight (Mn) 1700, weight average molecular weight (M
w) / number average molecular weight (Mn) = 1.28, acid value 174 m
gKOH / g (solid content conversion), hydroxyl value 25 mgKOH
/ G (as solid content) of a varnish with a nonvolatile content of 71% containing a carboxyl group-containing polyester resin.

(3) Synthesis of Polyoxy Group-Containing Acrylic Copolymer 500 parts of xylene was charged into a 2 L reaction tank equipped with a thermometer, a stirrer, a cooling pipe, a nitrogen introduction pipe, and a dropping funnel.
The temperature was raised to 5 ° C. Using a dropping funnel, 380 parts of glycidyl methacrylate, 200 parts of styrene, 292 parts of 2-ethylhexyl methacrylate, and acrylic acid
128 parts of 4-hydroxybutyl and 100 parts of t-butylperoxy-2-ethylhexanoate and xylene 10
0 parts of the solution was added dropwise over 3 hours.

After maintaining the temperature at 125 ° C. for 30 minutes after the completion of the dropwise addition, a solution comprising 10 parts of t-butylperoxy-2-ethylhexanoate and 10 parts of xylene was added dropwise over 30 minutes. After completion of the dropping, the temperature is further increased to 125 ° C. for 1 hour.
To continue the reaction, number average molecular weight (Mn) 3700,
Polyoxy equivalent 400 (solid content equivalent), hydroxyl value 47 mg
A varnish having a nonvolatile content of 62% and containing an acrylic resin having an engineered oxy group of KOH / g (as solid content) was obtained.

(4) Synthesis of Silicate Graft Polymer Methyl silicate “MS-56” (trade name) manufactured by Mitsubishi Chemical Corporation is subjected to an alcohol exchange reaction with isopropyl alcohol to obtain a 100% nonvolatile content containing an alcohol-modified silicate compound. A composition was obtained. Alcohol exchange reaction conditions were as follows: 74 g of “MS-56” was mixed with 21 g of isopropyl alcohol and 0.2 g of triethylamine, reacted at a temperature of 80 ° C. for 12 hours, and distilled methanol generated under reduced pressure. I left.

The interior of a 1 L reaction vessel equipped with a thermometer, a condenser, a cooling pipe and a nitrogen introduction pipe was replaced with nitrogen gas, and 100 parts of the above alcohol-modified silicate compound and the above-mentioned acrylic polymer 270 containing a oxy group were modified. And 2 parts of trimethyl orthoacetate were added thereto, and a graft reaction was performed at 90 ° C. for 12 hours. A varnish having a nonvolatile content of 72% containing a silicate graft polymer which was an epoxy group-containing acrylic copolymer grafted with a silicate compound was obtained. Obtained.

The components and additives prepared in the above (1) to (4) were blended at the ratios shown in Table 1 while dispersing them together to obtain an acid-epoxy curable hydrophilic clear coating material A for automotive top coating. .

[Table 1]

Production Example 2 Ubix OB (manufactured by CIBA-GEIGY) as a fluorescent substance was blended with clear paint A obtained in Production Example 1 at a blending amount of 10, 100 and 500 ppm, and a fluorescent substance blended clear paint was prepared. A1 to A3 were prepared. Each of the obtained paints A1 to A3 was butyl acetate /
It was diluted to a coating viscosity with a thinner consisting of xylene = 1/1.

Examples 1 to 3 In a laminated coating film formed by sequentially applying a color base paint and a clear paint on an outer layer (ie, a steel plate) of a car body of an automobile, the presence of each paint film is determined by blending a fluorescent substance. The extent to which can be determined was examined.

On a phosphoric acid-treated steel sheet, a cationic electrodeposition paint “Power Top V-20” manufactured by Nippon Paint Co., Ltd. and a polyester / melamine type gray intermediate paint “Olga TO H-87”
0 "(both are trade names), each having a dry film thickness of 25
μm and 40μm to paint and heat cured,
A test plate was used. Three test plates prepared in the same manner were prepared.

Each test plate was provided with “Olga T” manufactured by Nippon Paint Co., Ltd.
A silver metallic base paint of "OH-300" (trade name) was applied, and the phosphor-containing clear paints A1 to A3 prepared in Production Example 2 were applied on the wet-on-wet, respectively.

Thereafter, the coating was baked and dried at 140 ° C. for 30 minutes to prepare three coating test plates of two coats and one bake (2CIB) as a coating method. Each of the cured coating films formed by the base paint and the clear paint was applied so that the dry film thickness became 15 μm and 40 μm, respectively. FIG. 1 shows a schematic cross-sectional view of the obtained cured coating film.

The surface of the cured coating film was irradiated with black light (a wavelength of 360 nm, manufactured by Kawashima Koki Co., Ltd.), and it was evaluated whether the luminescence from the fluorescent substance could be confirmed with the naked eye. The evaluation results are indicated by れ ば when light emission from the fluorescent substance can be confirmed by irradiation with black light, and x when not. The results are summarized in Table 2 below.

Comparative Example As a comparative example, the acid for automotive top coating obtained in Preparation Example 1 was prepared.
A cured coating film was formed on a steel plate in the same procedure as in the example except that the epoxy-curable hydrophilic clear coating material A was used. The surface of the cured coating film was irradiated with black light in the same manner as in the example. Since this clear coating material A did not contain a fluorescent substance, no light emission could be confirmed even when irradiated with black light. Table 2 shows the results.

[0044]

[Table 2]

As can be seen from the results shown in Table 2, by incorporating at least 100 ppm of a fluorescent substance into the colorless and transparent clear paint, the luminescence due to the irradiation of black light can be visually discriminated. Was easily discerned with the naked eye.

[0046]

According to the method of the present invention, the presence of the coating film can be immediately confirmed, preferably by the naked eye, by causing the fluorescent substance in the coating film to emit light by irradiation of ultraviolet light or near ultraviolet light. Can be determined. In particular, the fluorescent substance-containing paint used in the present invention emits light only when irradiated with ultraviolet or near-ultraviolet light, and is difficult to visually recognize under visible light, so that the appearance and design of a coating film containing the same can be improved. It does not impair and does not cause any discomfort at all.

According to the present invention, a coating material containing a fluorescent substance can be applied by any means regardless of the coating method, the coating area and the shape. It is possible to determine the film. Also, by changing the blending amount of the fluorescent substance in the paint, or by selecting the coating site as needed, not only can the emission intensity of the fluorescent substance be changed, but also the period during which light can be emitted is shortened or extended. It is also possible.

The present invention not only determines the coating film immediately after coating, but also mounts a part on a predetermined portion after a certain period of time after coating and inspects an object to be coated including the coating film. Or applied to repair coatings.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a cured coating film formed in an example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steel plate, 2 ... Cathodic electrodeposition coating, 3 ... Intermediate coating, 4
... Base coating, 5 ... Clear coating

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Claims (1)

[Claims] An ultraviolet or near-ultraviolet ray is applied to a coating film formed by coating a paint containing a fluorescent substance on at least a part of a vehicle body and parts of an automobile, and the coating is performed by light emission from the fluorescent substance. A method for discriminating a film and discriminating a coating film formed on an automobile body and parts.