JP2003286418A - Paint for exterior part of vehicle, coating film for exterior part of vehicle using the same and vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrophilic paint forming a hydrophilic coating film having high durability and a vehicle wherein stain can be removed easily using the same. <P>SOLUTION: In a coating material for an exterior part of a vehicle comprising at least a hydrophilic component, a support-forming component maintaining the hydrophilic component and a liquid dispersing or dissolving the hydrophilic component and the support-forming component, the coating material for the exterior part of the vehicle, the coating film and the vehicle using the coating film for the most exterior part are characterized in that the hydrophilic component comprises alumina particles or colloidal silica particles and the support- forming component comprises a thermally cured product of silica sol. It is possible to provide the hydrophilic coating material forming the hydrophilic coating film having high durability and the vehicle wherein stain can be removed easily using the same. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating material for vehicle exteriors such as automobiles and trains, a vehicle exterior coating film using the same, and a vehicle using the same.

[0002]

2. Description of the Related Art A plurality of processes (undercoating, intermediate coating, topcoating, etc.) are carried out in exterior coating of vehicles such as automobiles, each of which has improved adhesion to a substrate and improved corrosion resistance.
Has a role of imparting gloss. Various resins are used for these paints. Above all, a hard coating film that is unlikely to be scratched or the like tends to be formed on the outermost surface (or also called top coat). In recent years, the outermost coating film has a tendency to have hydrophilicity so that dirt such as mud and dust can be easily removed by washing with water. As an example of imparting hydrophilicity to the outermost package, a paint containing a nonionic hydrophilic component (Japanese Patent Laid-Open No. 11-131016 and Japanese Patent Laid-Open No. 2000-178335).
JP-A-9-29375) and those using titanium oxide as a hydrophilic component have been widely proposed (WO96 / 29375, JP-A-9-).
77535, JP-A-10-146251). In particular, titanium oxide is drawing attention because it can form a highly hydrophilic surface having a contact angle with water of 20 ° or less. When titanium oxide is irradiated with light (mainly ultraviolet light), it forms hydrophilic radicals on the surface and exhibits hydrophilicity.
The principle that dirt on the hydrophilic surface is removed by washing with water is
When water is applied to the surface, the water circulates under the dirt to form a water film, and the dirt floats above the water film and is removed.

[0003]

However, since titanium oxide does not exhibit hydrophilicity unless it is irradiated with light (mainly ultraviolet light), there is a problem that sufficient effect cannot be exhibited at night. Further, even in the daytime, there is a problem that the sufficient effect cannot be exhibited even in the case of bad weather such as cloudy weather or rain.

Therefore, an object of the invention according to the present application is to provide a coating film that exhibits hydrophilicity without being irradiated with light, a coating material that forms the coating film, and a vehicle using the coating film. To do.

[0005]

[Means for Solving the Problems] As a result of studies for solving the above problems, as a result of using alumina particles or colloidal silica particles as a hydrophilic component, and silica sol as a support-forming component holding a hydrophilic component, visible light transmission is achieved. The present invention has been accomplished by finding a coating film having a high rate and maintaining hydrophilicity even when not exposed to light, and a coating material forming the coating film.

The concrete contents of the means of the present invention are described below. (1) A vehicle exterior coating material comprising at least a hydrophilic component, a carrier-forming component that holds the hydrophilic component, and a liquid that disperses or dissolves the hydrophilic component and the carrier-forming component, wherein the hydrophilic component is alumina particles and is retained. The body forming component is a thermosetting product of silica sol. (2) A vehicle exterior coating material comprising at least a hydrophilic component, a carrier-forming component that holds the hydrophilic component, and a liquid that disperses or dissolves the hydrophilic component and the carrier-forming component, wherein the hydrophilic component is colloidal silica particles, The carrier-forming component is silica sol. (3) In (1), the amount of the alumina particles added to the coating material is 2.5 to 20 times that of silica sol. (4) The vehicle exterior coating material as described in (2), wherein the amount of the colloidal silica added to the coating material is 2.5 to 20 times that of silica sol. (5) A vehicle exterior coating used at least as an outermost vehicle exterior, wherein the coating has a contact angle with water of 15 ° or less, and the main coating components are thermosetting products of alumina particles and silica sol. It is characterized by (6) A vehicle exterior coating film used at least as an outermost vehicle exterior, wherein the coating film has a contact angle with water of 15 ° or less, and the main coating film constituents are thermosetting products of colloidal silica and silica sol. It is characterized by (7) In a vehicle having a coating film, the coating film formed on the outermost part of the vehicle has alumina particles and a thermosetting substance of silica sol, and the contact angle with water is 15 ° or less. Is characterized by. (8) In a vehicle having a coating film, the coating film formed on the outermost part of the vehicle has colloidal silica and a thermosetting substance of silica sol, and the contact angle with water is 15 ° or less. Is characterized by.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a hydrophilic coating film formed on the outermost surface of a vehicle, a paint for forming the hydrophilic coating film, and a vehicle having the coating film. A schematic view of the cross section of the coating film is shown in FIG. The hydrophilic coating film is a coating film having the hydrophilic material 2 and the holder 3 on the underlayer 1. In the present invention, the underlayer is a layer in which pigments and mica are dispersed, or a clear layer. Embodiments of the present invention will be described below. [1] Hydrophilic Paint (1) Outline of Hydrophilic Paint A hydrophilic coating film formed of a hydrophilic paint is required to have high abrasion resistance and high visible light transmittance so as not to impair the color and gloss of the base. As a result of studying these problems, it was found that a hydrophilic coating film in which hydrophilic alumina particles or hydrophilic silica particles are held by SiO ₂ is effective. This hydrophilic coating film is formed by applying a coating material obtained by mixing the above materials and the raw materials thereof to the underlayer, and then heating. Further, pretreatment for improving wettability with a coating material and adhesion with a coating film to be formed before coating is also effective. The constituent materials of the hydrophilic paint are as follows.

(2) Paint constituent material A mixture of a dispersion containing hydrophilic alumina particles or hydrophilic silica particles and a solution of silica sol (alkoxysilane polymerized to several thousands with an average molecular weight) is used as a paint. . When this coating material is used, film formation is completed by heating after coating the glass. Hydrophilic alumina particles and hydrophilic silica particles mainly exhibit hydrophilicity in this coating material, and silica sol mainly functions as a holder for these particles. Therefore, the hydrophilicity can be increased by increasing the proportion of hydrophilic alumina particles or hydrophilic silica particles. Also, the physical strength of the film is improved by increasing the proportion of silica sol. Hydrochloric acid, nitric acid, phosphoric acid, etc. may be added to the silica sol solution in order to accelerate intermolecular polymerization, but in the case of hydrophilic silica, the dispersion is basic in order to improve dispersion. There are cases.
Therefore, when both are mixed, the hydrophilic silica may aggregate. Therefore, pay attention to the liquid state and the situation of dispersion of the hydrophilic silica when mixed. When dispersion is a problem, a non-aqueous solvent is preferably used as the solvent. In the case of hydrophilic alumina, since the dispersion liquid is mainly acidic, there are few troubles during mixing.

As the hydrophilic silica, colloidal silica MT-ST, IPA-ST, EG manufactured by Nissan Chemical Co., Ltd.
-ST, EG-ST-ZL, NPC-ST, DMAC-
ST etc. are mentioned. In the case of hydrophilic alumina, Alumina sol No. 520 may be used.

Alkoxysilane as a raw material of silica sol is methyltrimethoxysilane, ethyltrimethoxysilane, butyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, butyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, etc. Is mentioned. About 0.1% of the weight of dilute hydrochloric acid, dilute nitric acid, or dilute phosphoric acid is added to an alcohol solution (alcohol is mainly methanol or ethanol) dissolved in several% of these, and the mixture is stirred at 50-60 ° C for about 1 hour. A desired silica sol solution is obtained.

The solvent for the paint is preferably an alcoholic solvent (methanol, ethanol, isopropanol, etc.) that has little effect on the underlying resin. Water increases the surface tension of paint. For this reason, the paint is easily repelled from the base, and if it is not added as much as possible, the film-forming property tends to be excellent. [2] Hydrophilic coating film formation process In forming a coating film, pretreatment is performed to improve the wettability of the coating material and the adhesion between the base and the coating film. Next, application is carried out, and the finally applied paint is cured. (1) Pretreatment It is desirable that the hydrophilic film formed on the outermost package improves the adhesion to the underlayer and the wettability of the coating material during coating. Performing this treatment results in improvement in abrasion resistance.

Examples of the pretreatment method include oxygen plasma, ozone, and ultraviolet light irradiation. This means that oxygen plasma and ozone form hydroxyl groups on the surface of the underlayer, resulting in an increase in the coverage of the water repellent material. When ultraviolet light is irradiated, oxygen in the vicinity of the surface of the base becomes ozone, which forms hydroxyl groups on the surface of the base, and as a result, the coverage of the water repellent material increases. (2) Coating / Curing Step A dispersion containing hydrophilic alumina particles or hydrophilic silica particles is mixed with the silica sol solution to prepare a hydrophilic coating material for forming a hydrophilic coating film.

By applying the hydrophilic coating on the surface of the substrate and then heating, the silica sol is crosslinked to become a solid of SiO ₂ . A hydrophilic coating film is formed in such a manner that this holds the hydrophilic alumina particles and the hydrophilic silica particles.

The coating method may, for example, be spin coating, dipping or spraying. Further, it is desirable that the heating is performed at 160 ° C. or higher for several minutes in order to increase the strength of the film. However, when the heating temperature is lower than this, a hydrophilic coating film having high abrasion resistance is formed by slightly increasing the addition amount of hydrochloric acid, nitric acid or phosphoric acid, or extending the heating time.

If the substrate cannot be sufficiently heated due to heat resistance, it can be dealt with by irradiation with ultraviolet light. This is that the applied ultraviolet light energy is absorbed by the applied paint and converted into heat energy, and as a result, heat is applied only to the paint to accelerate curing. (Examples) Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to these Examples.

(Example 1) (1) Preparation of hydrophilic coating 6% by weight of silica sol solution (average molecular weight 4000, phosphoric acid acidic) (1 part by weight), 20% by weight of hydrophilic alumina (Alumina sol No. 520 manufactured by Nissan Chemical Industries, Ltd.) ) (1 part by weight),
Mix with ethanol (15 parts by weight). Thus, the hydrophilic paint is prepared.

(2) Pre-painting process Normal painting process {primer coating (priming treatment), intermediate coating
(Paint / mica layer formation), top coating (clear coating)} The exposed surface of the automobile door is irradiated with ultraviolet rays by a high pressure mercury lamp. The intensity of irradiation light is 12 mW / cm ² , and the irradiation time is 3 minutes. This reduces the contact angle of the coated surface with water to 20 ° or less.

(3) Filling / heating step The hydrophilic paint prepared in (1) is filled in a spray paint tank. Using this spray, apply a hydrophilic paint to the painted surface of the automobile door that has been irradiated with UV light, and then apply 160 ° C.
It heats for 20 minutes in the constant temperature bath controlled to. Through the above steps, a hydrophilic coating film is formed on the coated surface. Finally, attach this door to the corresponding car.

(4) Evaluation test Initial contact angle, hardness measurement, mud removal time The thickness of the hydrophilic coating film formed was 0.1 μm on average, and the contact angle with water was 10 ° or less. Unlike titanium oxide, this value was the same in the dark. This is because the hydrophilicity of the coating film is hydrophilic alumina, and this material does not remarkably increase in hydrophilicity when exposed to light unlike titanium oxide. The pencil hardness was 2H.

Next, in order to examine the ease of removing the mud in the coating film, carbon black (1 part by weight) and water (3 parts by weight) were thoroughly stirred to prepare a mud-simulating substance, which was used to form a hydrophilic coating film. When 1 g / cm ^{2 was} adhered to the door and dried at 50 ° C. for 8 hours and then 20 g / sec of water was applied, the mud-simulating substance in the water-exposed portion all fell off within 5 seconds. Weather resistance test The portion where the hydrophilic coating film is formed is examined for weather resistance of the hydrophilic film using a sunshine carbon arc lamp type weather resistance tester (manufactured by Suga Test Instruments Co., Ltd.). The test temperature was 63 ° C., and water was sprayed for 2000 hours under the conditions of 120 minutes of rainfall and 18 minutes of rainfall. After the test, the contact angle with water, pencil hardness, and were measured. As a result, the contact angle with water is 10 ° or less, and the pencil hardness is 2H.
Met. This value was the same in the dark.

Next, when the easiness of removing the mud of the coating film was examined, even after the end of the weather resistance test, when a water amount of 20 g / sec was applied, all the mud-simulating substances flowed off within 5 seconds.

From the above, the hydrophilic coating film of the present invention has a hydrophilic property of 10
It was shown to be less than ° and high in durability. It was also shown that the hydrophilic coating material of the present invention can form a highly durable hydrophilic coating film. Further, it has been shown that the vehicle having the hydrophilic coating film of the present invention has a painted surface on which stains can be easily removed.

Example 2 Instead of 20% by weight of hydrophilic alumina (Alumina sol No. 520 by Nissan Chemical Co., Ltd.) (1 part by weight), 30% by weight silica sol liquid (Snowtex IPA-ST by Nissan Chemical Co., Ltd.) (1% by weight) The same test as in Example 1 was performed except that the parts) were used, but there was no difference in contact angle, hardness, and ease of removing the substance simulating mud before and after the weather resistance test.

Further, unlike titanium oxide, the value of the contact angle was the same even in the dark. This is because the hydrophilicity of the coating film is colloidal silica, and this material does not significantly increase its hydrophilicity under light irradiation unlike titanium oxide.

(Example 3) 6 wt% silica sol solution (average molecular weight 4000, phosphoric acid acidic) (1 part by weight), ethanol (15 parts by weight) without changing 20% by weight of hydrophilic alumina (manufactured by Nissan Kagaku) Alumina sol No. 520)
6 parts by weight, 0.75 parts by weight, 1.5 parts by weight, 2 parts by weight,
Eight kinds of hydrophilic paints are prepared as 3 parts by weight, 6 parts by weight, 9 parts by weight, or 15 parts by weight. Table 1 shows the ratio of the solid content of hydrophilic alumina to the bulk silica sol.

[0026]

[Table 1]

The door 8 of the automobile after the normal painting process is completed.
Each coated surface was irradiated with ultraviolet rays by a high pressure mercury lamp in the same manner as in Example 1, and one door was prepared per one kind of hydrophilic paint prepared.
They are applied individually by spraying and then heated for 20 minutes in a constant temperature bath controlled at 160 ° C. Through the above steps, eight kinds of samples having a hydrophilic coating film formed on the coated surface are obtained. Finally, attach this door to the corresponding car.

As in Example 1, initial contact angle and hardness measurement,
When the mud removal time was measured, it was as shown in Table 1. The results of Example 1 are also shown. Next, a weather resistance test was carried out in the same manner as in Example 1. The results are shown in Table 1. Table 1 also shows the evaluation of the door on which the hydrophilic coating film is not formed.

The initial contact angle of the door on which the hydrophilic coating film is formed is 20% by weight of the hydrophilic coating used when the amount of hydrophilic alumina added is less than 0.75 part by weight (ratio of solid content of hydrophilic alumina to silica sol in bulk). Is less than 2.5) is 15 °
All were 10 ° or less except for. The removal time of the substance simulating mud was 5 seconds when the hydrophilic coating film was formed and 30 seconds or more when the hydrophilic coating film was not formed, so the effect can be expected even at 15 °.

The pencil hardness is HB when the addition amount of hydrophilic alumina of 20% by weight exceeds 6 parts by weight (the ratio of the solid content of hydrophilic alumina to the bulk silica sol exceeds 20), but otherwise. It had a hardness of H or higher. However, for those that do not form a hydrophilic coating, the weather resistance test is H
However, since it was HB after the weather resistance test, there is no problem even when the addition amount of the hydrophilic alumina of 20% by weight exceeds 6 parts by weight.

From the above, the hydrophilic coating film of the present invention has a hydrophilic property of 15
It was shown to be less than ° and high in durability. It was also shown that the hydrophilic coating material of the present invention can form a highly durable hydrophilic coating film. Further, it has been shown that the vehicle having the hydrophilic coating film of the present invention has a painted surface on which stains can be easily removed.

The coating composition has a hydrophilic alumina solid content ratio of not less than 2.5 and not more than 20 with respect to the bulk silica sol, and the hydrophilic coating film formed has a contact angle with water of not more than 10 °. Moreover, since the pencil hardness was H or more, it was shown that stains were easily removed and a coating film that was not easily scratched was given.

Similarly, as a coating composition, particularly for an automobile having a hydrophilic coating film formed with a hydrophilic alumina solid content of 2.5 or more and 20 or less with respect to bulk silica sol, stains on the coated surface are removed. It was shown to have a coating that is easy and scratch resistant.

(Example 4) 6 wt% silica sol solution (average molecular weight 4000, phosphoric acid acidic) (1 part by weight), ethanol (15 parts by weight) without changing 30% by weight of colloidal silica (Nissan Chemical Snow Tex IPA-ST)
9 parts of hydrophilicity as 0.3 parts by weight, 0.5 parts by weight, 0.7 parts by weight, 1.5 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 6 parts by weight, or 10 parts by weight. Prepare the paint. Table 2 shows the ratio of the colloidal silica solid content to the bulk silica sol.

[0035]

[Table 2]

The door 9 of the automobile after the usual painting process is completed.
Each coated surface was irradiated with ultraviolet rays by a high pressure mercury lamp in the same manner as in Example 1, and one door was prepared per one kind of hydrophilic paint prepared.
They are applied individually by spraying and then heated for 20 minutes in a constant temperature bath controlled at 160 ° C. Through the above steps, 9 kinds of samples having a hydrophilic coating film on the coated surface are obtained. Finally, attach this door to the corresponding car.

Initial contact angle and hardness measurement as in Example 1,
When the removal time of mud was measured, it was as shown in Table 2. The results of Example 2 are also shown. Next, a weather resistance test was carried out in the same manner as in Example 1. The results are shown in Table 2. Table 2 also shows the evaluation of doors on which a hydrophilic coating film is not formed.

The initial contact angle of the door on which the hydrophilic coating film is formed is 30% by weight of the hydrophilic coating material used and the amount of colloidal silica added is less than 0.5 parts by weight (the ratio of the solid content of the colloidal silica to the bulk silica sol is 2). Less than .5) is 15 °
All were 10 ° or less except for. The removal time of the substance simulating mud was 5 seconds when the hydrophilic coating film was formed and 30 seconds or more when the hydrophilic coating film was not formed, so the effect can be expected even at 15 °.

The pencil hardness is HB when the amount of colloidal silica added at 30% by weight exceeds 6 parts by weight (when the ratio of the solid colloidal silica solid content to the bulk silica sol exceeds 20), but otherwise H or higher. Had a hardness of. However, those which did not form a hydrophilic coating film were H in the weather resistance test, but HB after the weather resistance test.
Even if the amount of colloidal silica added at 0% by weight exceeds 6 parts by weight, there is no problem.

From the above, the hydrophilic coating film of the present invention has a hydrophilic property of 15
It was shown to be less than ° and high in durability. It was also shown that the hydrophilic coating material of the present invention can form a highly durable hydrophilic coating film. Further, it has been shown that the vehicle having the hydrophilic coating film of the present invention has a painted surface on which stains can be easily removed.

As a coating composition, a hydrophilic coating film formed with a colloidal silica solid content ratio of 2.5 or more and 20 or less with respect to bulk silica sol has a contact angle with water of 10 ° or less and Since the pencil hardness was H or higher, it was shown that stains were easily removed and a coating film that was not easily scratched was provided.

Similarly, in the coating composition, the ratio of the colloidal silica solid content to the bulk silica sol is 2.5.
It has been shown that an automobile having a hydrophilic coating film formed of the above and 20 or less has a coating film that is easy to remove stains on the coated surface and is not easily scratched.

[0043]

According to the present invention, it is possible to provide a hydrophilic coating material which forms a highly durable hydrophilic coating film, and a vehicle using the hydrophilic coating material which easily removes dirt.

[Brief description of drawings]

FIG. 1 is a schematic view of a coating film cross section of the present invention.

[Explanation of symbols]

1 ... Underlayer, 2 ... Hydrophilic material, 3 ... Holder.

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Claims (8)

[Claims] 1. A vehicle exterior coating material comprising a hydrophilic component, a carrier-forming component that holds the hydrophilic component, and a liquid that disperses or dissolves the hydrophilic component and the carrier-forming component, wherein the hydrophilic component is A coating material for a vehicle exterior, which is an alumina particle, and the holding body-forming component is silica sol. 2. A vehicle exterior coating material comprising a hydrophilic component, a support-forming component that holds the hydrophilic component, and a liquid that disperses or dissolves the hydrophilic component and the support-forming component, wherein the hydrophilic component is A coating material for a vehicle exterior, which is colloidal silica particles, wherein the support-forming component is silica sol. 3. The vehicle exterior coating material according to claim 1, wherein the amount of the alumina particles added to the vehicle exterior coating material is 2.5 to 20 times that of the silica sol. 4. A vehicle exterior coating material, wherein the amount of the colloidal silica added to the vehicle exterior coating material is 2.5 to 20 times that of silica sol. 5. A coating used for the outermost part of a vehicle, wherein the coating has a thermosetting material of alumina particles and silica sol,
A coating film having a contact angle with water of 15 ° or less. 6. A coating used for the outermost part of a vehicle, wherein the coating has a thermosetting product of colloidal silica and silica sol and has a contact angle with water of 15 ° or less. film. 7. A vehicle having a coating film, wherein the coating film formed on the outermost portion of the vehicle comprises alumina particles and a thermosetting substance of silica sol, and has a contact angle with water of 15 ° or less. A vehicle characterized by: 8. A vehicle having a coating film, wherein the coating film formed on the outermost portion of the vehicle has colloidal silica and a thermosetting substance of silica sol, and has a contact angle with water of 15 ° or less. A vehicle characterized by: