JPH01249176A - Method for coating resin member - Google Patents

Abstract

PURPOSE:To improve the adhesion of a paint film to a resin member by subjecting primer coating on the member to surfacer coating with two-pack urethane coating and by carrying out baking and drying at a low temp. or catalytic curing. CONSTITUTION:A resin member 1 is washed, coated with polyolefin resin-based primer paint having <=-40 deg.C glass transition temp. and further coated with two-pack urethane paint. The paints are baked and dried at a low temp. of about <80 deg.C to form a polyolefin resin primer layer 2 and a urethane surfacer layer 3 on the surface of the resin member 1. The layer 3 is then coated with color paint for a steel sheet such as melamine-alkyd resin paint and this coating is baked and dried at a high temp. of about 130-150 deg.C to form a top coating layer 5 on the surface of the layer 3.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention is applicable to resin members, such as SMC (sheet
The present invention relates to a method for coating resin members used for coating resin members (molding compound). (Prior art) The purpose of painting, especially as a final finishing process for automobile bodies and parts, is to prevent rust and add beauty, just like general painting purposes.This kind of painting is described in the new Automotive Engineering Handbook, Volume 9. There is a general description on pages 1-70 to 1-77. In recent years, resin parts have been increasingly used to reduce the weight of car bodies, improve weather resistance and design, and improve productivity through mass production. The number of cases where this is the case is increasing. Conventionally, for example, when painting SMC resin members, the sixth
There were methods shown in Fig. 7 and Fig. 7, and methods shown in Figs. 8 and 9. Of these, the former method shown in FIGS. 6 and 7 is to clean the SMC resin member 11, only the surface layer of which is shown in FIG. By applying a primer coating consisting of a primer coating and baking and drying at 80°C,
As shown in FIG. As shown in the figure, an overcoat layer 14 is applied to the surface of the polyester resin primer layer 12.
This is a method of forming In addition, in the latter method shown in FIGS. 8 and 9, after cleaning the SMC resin member 11, only the surface layer of which is shown in FIG. Applying brimer paint By applying brimer paint and baking and drying at 80°C, a polyester resin primer layer 12 is formed on the surface of the wood member 11 as shown in FIG. By applying an intermediate coating and baking and drying at 140°C, an intermediate coating layer 13 is formed on the surface of the polyester resin primer layer 12 as shown in FIG. 9, and a color coating for steel sheets is further applied. By baking and drying at 140° C., the top coat layer 14 is formed on the surface of the intermediate coat layer 13, as shown in FIG. (Problems to be Solved by the Invention) However, in such conventional painting methods for resin members, the brimer paint made of polyester resin was baked and dried at 80°C and 140°C, so the stone It is vulnerable to chipping impact, and the paint film tends to peel off easily. Moreover, since this primer paint made of polyester resin is a high temperature baking dry type, when the color paint for steel plate is baked and dried at high temperature, air bubbles in the surface layer of the resin member 11 pop out and the polyester resin primer layer 12 There is a problem in that it can cause coating defects in the form of pinholes and may require repair of the putty fill, and it has been an issue to solve these problems. (Purpose of the Invention) This invention was made in view of the above-mentioned conventional problems, and it provides a coating film that has good adhesion to resin members and has excellent stone chipping and impact resistance. It is an object of the present invention to provide a method for painting a resin member, which is capable of forming a coating film that is difficult to cause coating defects and does not require putty correction.

[Structure of the invention]

(Means for Solving the Problems) A method for coating a resin member according to the present invention is to coat the resin member with a brimer paint containing a polyolefin resin as a main component and having a glass transition temperature (Tg point) of -40°C or lower. After applying a primer coating to apply the
After baking and drying or catalytically curing (temperature lower than
It is characterized by a structure that performs baking drying (approximately 150℃) as a means to solve the conventional problems, and if necessary, after surfacer coating, low temperature baking drying or catalytic hardening, steel plate After applying an intermediate coat of paint, baking and drying at a high temperature (for example, about 130 to 150 degrees Celsius), apply a color coating of the above-mentioned melamine alkyd or acrylic color paint for steel sheets, and baking at a high temperature. It is characterized by using a configuration that performs drying as a means to solve the conventional problems. FIG. 1 shows an embodiment of the coating method for resin members according to the present invention. First, after cleaning the resin member 1 whose surface layer is shown only in FIG. , a primer coating is applied by applying a brimer paint whose main component is polyolefin resin and a glass transition temperature of 140°C or less, and then a surfacer coating is applied by applying a two-component urethane paint, and then a low temperature (e.g. 80°C) is applied. Less than 9
By performing baking drying (as shown in the figure, at 60° C. for 20 minutes), a polyolefin resin primer layer 2 and a two-component urethane surfacer layer 3 are formed on the surface of the resin member 1, as shown in FIG. Next, a color coating is applied using a melamine alkyd or acrylic color paint for steel sheets, followed by baking drying at a high temperature (e.g., 130 to 150 degrees Celsius, 140 degrees Celsius in the illustration). As shown, an overcoat layer 5 is formed on the surface of the surfacer layer 3. FIG. 2 shows another embodiment of the method for coating a resin member according to the present invention. First, after cleaning the resin member 1 whose surface layer is only shown in FIG. To,
By applying a brimer coating, which is a brimer coating whose main component is a polyolefin resin and whose glass transition temperature is 140 degrees Celsius or less, then a surfacer coating, which is a two-component urethane-based surfacer coating, and catalytic curing. , as shown in FIG. 3, the resin member 1
A polyolefin resin primer layer 2 and a two-component urethane facer layer 3 are formed on the surface of the substrate. Next, color painting is applied by applying a melamine alkyd or acrylic color paint for steel sheets, and a high temperature (for example, 13
By performing baking drying at a temperature of 0 to 150°C (140°C as shown), an overcoat layer 5 is formed on the surface of the surfacer layer 3, as shown in FIG. In this embodiment, the catalytic curing method is used to dry the surfacer paint, so the baking drying process only needs to be carried out once. FIG. 4 shows another embodiment of the method for coating resin members according to the present invention. First, after cleaning the resin member 1 whose surface layer only is shown in FIG. To,
Brimer painting is applied, which is a primer paint whose main component is polyolefin resin and has a glass transition temperature of 140 degrees Celsius or less, followed by surfacer painting, which is a two-component urethane-based surfacer paint, followed by low-temperature baking drying or catalytic coating. By curing, a polyolefin resin primer layer 2 and a two-component urethane facer layer 3 are formed on the surface of the resin member 1 as shown in FIG. 5. Next, an intermediate coating for steel plates is applied. By applying the coating and baking drying at a high temperature (for example, about 130 to 140° C., 140° C. in the figure), an intermediate coating layer 4 is formed as shown in FIG. 5 as well. Next, color painting is applied by applying melamine alkyd or acrylic color paint for steel sheets, and then heated to a high temperature (e.g. 1.30~
By performing baking drying at about 150° C. (140° C. in the illustration), a top coat layer 5 is formed on the surface of the intermediate coat layer 4, as shown in FIG. The resin member 1 used in the resin member coating method according to the present invention includes one made of SMC resin. The SMC resin that is the material of this SMC resin member 1 is a sheet-like material obtained by impregnating polyester into a glass mat or glass fiber and proceeding with a curing reaction halfway. When molding, compression molding, matte die molding, etc. are used. However, the resin member 1 to which the present invention is applied is not limited to the above-mentioned SMC resin member. Next, when coating the resin member 1 with a brimer, a brimer paint containing a polyolefin resin as a main component and having a glass transition temperature (Tg point) of -40° C. or lower is used. In this case, if the glass transition temperature of the polyolefin resin is high, it will be difficult to form a uniform coating film.
Since the film-forming performance deteriorates, it is necessary to use a brimer paint whose main component is a polyolefin resin with a glass transition temperature of 140° C. or lower. In the surfacer coating applied after the brimer coating, a two-component urethane paint is used as the surfacer paint. This two-component urethane paint uses acrylic polyols, alkyd polyols, polyester polyols, and polyols made of modified products thereof as resins, and as curing agents, toluene diisocyanate,
Single incyanates such as xylene diisocyanate and inphorone diincyanate are used. Next, after painting the surfacer, low-temperature baking drying or catalytic curing is performed, but the former low-temperature baking drying should be carried out at a temperature of less than 80°C, which is lower than conventional methods, and the latter catalytic curing should be performed by applying a curing catalyst just before painting. Use by mixing with the main paint agent. Examples of the curing catalyst include aliphatic amines such as trimethylamine and triethylamine, aromatic amines such as dimethylaniline and diethylaniline, alkanolamines such as triethanolamine and methyljetanolamine, tetramethyldiamine, and tetramethylhexamethylenediamine. Single diamines and triamines such as these are used. Subsequently, after drying by low-temperature baking or catalytic curing, an intermediate coating is applied as necessary. An intermediate coating for steel plates is used for this intermediate coating. In the color coating applied to this surface layer, 1. Melamine alkyd-based or acrylic-based color paints for steel plates are used, and those that take into consideration the design of the paint color of the vehicle body are used. Next, after color coating, high-temperature baking drying is performed, and this high-temperature baking drying is carried out at, for example, 130 to 150° C., as in the case of conventional drying after color coating. (Function) In the method for coating resin members according to the present invention, by using two types of paint, a polyolefin-based brimer paint and a two-component urethane-based surfacer paint,
The functions required for a brimer include a coating film that has good adhesion and stone impact resistance, and a coating that cures at low temperatures and can suppress the popping of air bubbles on the surface layer of resin parts even when high temperatures are applied later. Since it is provided separately from the paint film, it has excellent adhesion and stone impact resistance, and does not cause side-like (pinhole-like) coating defects due to air bubbles popping out. (Example) First, after cleaning the SMC resin member to make the surface clean, a primer paint containing polyolefin resin as the main component (here, special modified polyolefin elastomer 10
%, special modified polyurethane 2%, carbon 0.3%, solvent 87.7%; 15 points below -40℃) is applied to a thickness of 10 gm, and then without heating and drying. , a surfacer paint mainly composed of two-component polyurethane resin paint (here, 62% acrylic polyol, 8% titanium dioxide, 6.6% xylene)
, 10% butyl acetate, 10% methyl ethyl ketone, 3.4% other additives, and a curing agent) was added to 20 JL.
S
A polyolefin resin primer layer and a two-component polyurethane resin surfacer layer are formed on the surface of the MC resin member. Next, an intermediate coating is applied with an intermediate coating for steel plates, and then baked and dried at a high temperature (140°C for 30 minutes). By doing this, an intermediate coating layer is formed, and then a color coating is applied by applying a melamine alkyd color paint for steel plates.
A top coat layer was formed on the surface of the intermediate coat layer by baking and drying at a high temperature (140° C. for 30 minutes). Example 2 First, after cleaning the SMC resin member to make the surface clean, a primer coating containing a polyolefin resin as the main component was applied to a thickness of 10 gm, and then, without heating and drying, A sub-surfacer coating, which consists of a two-component polyurethane resin paint applied to a thickness of 20 pm, is applied at low temperatures (20 pm at 60°C).
A polyolefin resin primer layer and a two-component polyurethane resin surfacer layer were formed on the surface of the SMC resin member by baking and drying for 30 minutes). Subsequently, a color coating was applied by applying an acrylic color paint for steel sheets, and an overcoat layer was formed on the surface of the surfacer layer by baking and drying at a high temperature (140° C. for 30 minutes). First, the SMC resin parts were washed to make the surface clean, and then a primer coating containing polyolefin resin as the main component was applied to a thickness of 10 JLm.
Next, without heating and drying, a surfacer coating consisting of a two-component polyurethane resin coating as a main component is applied to a thickness of 20 pm, and catalytic curing is performed using an amine as a curing catalyst. A polyolefin resin primer layer and a two-component polyurethane resin surfacer layer were formed on the surface of the member. Subsequently, color painting was performed by applying a melamine alkyd color paint for steel sheets, and baking drying was performed at a high temperature (140° C. for 30 minutes) to form an overcoat layer on the surface of the surfacer layer. Comparative Example 1 First, after cleaning the SMC resin member to make the surface clean, surfacer coating was applied by applying a surfacer paint mainly composed of two-component polyurethane resin paint to a thickness of 20 lm, and then heated. Primer coating is applied to a thickness of 10gm with a primer coating mainly composed of polyolefin resin without drying.
A two-component polyurethane resin surfacer layer and a polyolefin resin primer layer were formed on the surface of the SMC resin member by baking and drying for 30 minutes). Subsequently, color painting was performed by applying an acrylic color paint for steel plates, and baking drying was performed at a high temperature (140° C. for 30 minutes) to form an overcoat layer on the surface of the primer layer. Itashiki Aヱ First, after cleaning the SMC resin member to make the surface clean, apply a surfacer paint that mainly consists of two-component polyurethane resin paint to a thickness of 201Lm, and then apply a surfacer paint at a low temperature (60°C A two-component polyurethane resin surfacer layer was formed on the surface of the SMC resin member by baking and drying for 20 minutes. continue,
An overcoat layer was formed on the surface of the surfacer layer by applying color coating using an acrylic color paint for steel plates and baking and drying at a high temperature (140° C. for 30 minutes). First of all, after washing the SMC resin parts to make the surface clean, apply a primer coating consisting of a primer coating mainly composed of polyester resin to a thickness of IOpm, and then apply a primer coating at a high temperature (80℃ for 20 minutes). ) to form a primer layer made of polyester resin on the surface of the SMC resin member.Next, an intermediate coating is applied by applying an intermediate coating for steel plates, and then baked at a high temperature (140℃ for 30 minutes). ) to form an intermediate coating layer, followed by color painting with an acrylic color paint for steel plates, followed by baking drying at a high temperature (140°C for 30 minutes). A top coat layer was formed on the surface of the intermediate coat layer. Test Example A chipping impact test and a thermal cycle test were performed on the painted SMC resin members shown in Examples 1 to 3 and Comparative Examples 1 to 3 above. In addition to conducting hot water resistance tests and moisture resistance tests, SWOM750H
Based on this, the difference in gloss between two colors, the appearance, and the roughness were investigated, and the presence or absence of popping air bubbles was also investigated. The results are shown in Table 1. In Table 1, O marks indicate that good results were obtained in each test, and X marks indicate that good results were not obtained. . As is clear from the results shown in Table 1, Examples 1 to 3 of the present invention are excellent in all of the two-way splash impact characteristics, heat cycle resistance characteristics, l1lFf hot water characteristics, and moisture resistance characteristics, and are excellent in preventing air bubbles from popping out. It was confirmed that the SMC resin member had good coating film performance without side-like coating defects due to the absence of coating defects. On the other hand, in Comparative Example 1 and Comparative Example 2, a two-component polyurethane resin paint is first applied to the surface of the resin member, so it is vulnerable to impact from stone chips (chipping) and the paint film easily peels off. In Comparative Example 3, a polyester resin paint, which is a high-temperature baking type paint, was applied, so air bubbles on the surface layer of the resin member were popped out due to the heating during baking, causing coating defects, and stones. It was also vulnerable to splash impact.

【Effect of the invention】

As described above, in the method for coating a resin member according to the present invention, a brimer coating is applied to the resin member, in which a brimer paint containing a polyolefin resin as a main component and having a glass transition temperature of 140°C or less is applied to the resin member. After that, a surfacer coating is applied using a two-component urethane paint, followed by low-temperature baking drying or catalytic curing, followed by color coating using a melamine alkyd or acrylic color paint for steel sheets, followed by high-temperature baking drying. Because I did it like this,
The adhesion of the paint film to the surface of the resin component after painting is extremely good, and it has excellent splash (chipping) and impact properties, as well as preventing coating defects due to air bubbles popping out on the surface of the resin component. The very excellent effect of being able to form a high quality coating film that does not wobble and does not require putty correction is brought about.

[Brief explanation of the drawing]

Figures 1 and 2 are process explanatory diagrams showing each embodiment of the method for coating resin members according to the present invention, and Figure 3 is a diagram showing the coating film obtained by the embodiment shown in Figures 1 and 2. FIG. 4 is a schematic explanatory diagram showing a cross-sectional structure, FIG. 4 is a process explanatory diagram showing another embodiment of the coating method for resin members according to the present invention, and FIG. A schematic explanatory diagram showing the cross-sectional structure of the film, FIGS. 6 and 7 are process explanatory diagrams illustrating a conventional coating method for resin members, and a schematic explanatory diagram of the cross-section of the coating film, FIGS. 8 and 9, respectively. These are process explanatory diagrams and schematic explanatory diagrams of a cross section of a coating film, respectively, illustrating another method of conventional coating methods for resin members. DESCRIPTION OF SYMBOLS 1... Resin member, 2... Primer layer, 3... Surfacer layer, 4... Intermediate coat layer, 5... Top coat layer. Patent applicant: Patent attorney representing Nissan Motor Co., Ltd.
Yutaka Ko Shio

Claims (1)

[Claims] (1) After applying a primer coating to resin parts, which is a primer coating whose main component is polyolefin resin and whose glass transition temperature is -40°C or lower, surfacer coating is applied, which is a two-component urethane coating. A method for painting resin members, which comprises applying a color coating, applying a melamine alkyd or acrylic color paint for steel plates after drying by baking at a low temperature or curing with a catalyst, and then baking and drying at a high temperature.