JPH0618910B2 - FRP molding method - Google Patents

Description

The present invention relates to a method for coating FRP molded products.

(Prior Art) Since many FRP molded products have pinholes on the surface of the material, various methods have been taken in coating to prevent coating defects due to pinholes.

For example, Japanese Examined Patent Publication No. 58-50254 describes a method for preventing coating film defects by applying a urethane resin paint as a primer paint and then applying an aminoalkyd resin paint in a wet-on-wet state. ing.

As another method, as a primer paint,
There is a method of applying urethane paint and baking at low temperature (80 ℃). Also, a method of preventing coating defects due to pinholes by using putty such as urethane type and epoxy type has been considered. Furthermore, a method of obtaining a filling effect by increasing the amount of pigments in the paint has been considered.

(Problems to be solved by the invention) However, in the case of a product having an adhesive surface, there are more pinholes on the surface in the vicinity of the adhesive surface than in other parts, and the diameter of the pinhole is larger. Are large and small. Therefore, when painting an FRP molded product such as the air spoiler described in Japanese Utility Model Publication No. 61-124481 in which the bonded portion becomes the design surface, there are many coating film defects due to pinholes near the bonded portion. This caused the appearance defect to be more serious than that in the case of coating a normal FRP molded product. In particular, in recent years, the FRP molded product portion is required to have the same initial quality and durability quality as those of the general surface of the vehicle body. Therefore, it is strongly desired to prevent these coating film defects.

In order to prevent coating film defects when coating an FRP molded product having such an adhesive surface, the above Japanese Patent Publication No. 58-50 is used.
Method 254 is not sufficient. Further, in the method in which a urethane-based paint is applied as a primer paint and baking is performed at a low temperature, the number of pinholes generated is slightly reduced by the decrease in the baking temperature, but this is not sufficient. In addition, the method of using putty such as urethane type and epoxy type is especially
When used in combination with the method of JP-B-58-50254, a high effect can be obtained, but since many man-hours are required for filling putty, man-hours increase and work efficiency decreases. Further, this method also has a problem that a pinhole having a relatively small diameter of 50 μm or less cannot be completely filled, so that a sufficient sealing effect cannot be obtained. Further, the method of obtaining a sealing effect by increasing the amount of the pigment in the coating material remarkably deteriorates the appearance after the top coating, and the sealing effect is not sufficient. Therefore, according to the present invention, it is possible to obtain the effect of preventing coating film defects due to sufficient pinholes even on the surface in the vicinity of the bonding surface, and FR without increasing the number of steps.
It is an object of the present invention to provide a method for coating P molded products.

(Means for Solving Problems) In order to achieve the above object, the method for coating an FRP molded article of the present invention comprises an acrylic polyol and a polyisocyanate compound as a primer coating, and a tin compound is added. The liquid urethane resin paint is applied at a liquid temperature of less than 60 ° C.

As the acrylic polyol, for example, a copolymer containing a methacrylic acid ester and a hydroxyl group-containing polymerizable monomer can be used. The copolymer preferably has a number average molecular weight of about 10,000 to 80,000 and a hydroxyl value of 20 to.
It has an acid value of 120 and an acid value of 50 or less.

As the polyisocyanate compound, one containing two or more isocyanate groups in one molecule can be used. Examples of these are hexamethylene diisocyanate,
Xylylene diisocyanate, hydrogenated xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, meta-xylene diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate, reaction products of these diisocyanates with water or polyhydric alcohol , Polymers of these diisocyanates, and mixtures of the above compounds.

The ratio of the acrylic polyol to the polyisocyanate compound is 0.4-based on the NCO / OH (molar ratio).
The range of 1.2, especially 0.8 to 1.0 is preferable.

The tin compound is added as a curing accelerator, and the following may be used, for example. Dibutyltin laurate, dibutyltin acetate, tetrabutyltin, tributyltin chloride,
Dibutyltin dichloride, butyltin trichloride, tin chloride, tributyltin-o-phenolate, tributyltin cyanate, tin octylate, tin oleate, tin tartrate, dibenzyltin di (2-ethylhexoate), dibutyltin dilaurate, dibutyltin diisooctyl maleate. Ate, dibutyltin sulfide, dibutyltin dibutoxide, dibutyltin bis (o-phenylphenolate), dibutyltin bis (acetylacetonate),
Di (2-ethylhexyl) tin oxide. Also, the following general formula: (In the formula, R represents the same or different alkyl group, X represents the same or different halogen atom, hydroxyl group, alkoxy group or acyloxy group.) The organotin compound represented by the formula also catalyses the reaction between the isocyanate group and water or the hydroxyl group. Since it has an action, it can be preferably used in the present invention.

Specific examples of such organic tin compounds include, for example, tetra-n-butyl-1,3-diacetyloxydistannoxane, tetra-n-propyl-1,3-diacetyloxydistannoxane, tetra-n-propyl-1. -Chloro-
3-hydroxydistannoxane, tetra-n-butyl-
1-chloro-3-hydroxydistannoxane, tetramethyl-1,3-diacetyloxydistannoxane, tetramethyl-1-chloro-3-acetyloxydistannoxane, tetra-n-butyl-1,3-di Formyloxydistannoxane, tetra-n-butyl-1,3-diacryloxydistannoxane, tetra-n-butyl-1,
3-Dioleyloxydistannoxane, tetra-n-butyl-1,3-distearyloxydistannoxane, tetra-n-butyl-1,3-diphenylacetyloxydistannoxane, tetra-n-butyl-1 , 3-diisocyanodistannoxane, tetra-n-butyl-1-acetyloxy-3-hydroxydistannoxane, tetra-n-propyl-1-acetyloxy-3-hydroxydistannoxane, tetramethyl-1 -Acetyloxy-
3-hydroxydistannoxane, tetra-n-butyl-
1,3-dichlorodistannoxane, tetramethyl-1,
3-dichlorodistannoxane, tetramethyl-1,3-
Dichlorodistannoxane, tetra-n-butyl-1,3
-Dipropoxy distannoxane, tetra-n-propyl-1,3-dipropoxy distannoxane, tetra-n-
Butyl-1-propoxy-3-acetyloxydistannoxane, tetra-n-propyl-1-hydroxy-3-
Ethoxydistannoxane, 1,1-dibutyl-3,3-
Dipropyl-1-hydroxy-3-acetyloxydistannoxane, 1,3-dipropyl-1,3-dibutyl-
1-chloro-3-hydroxy distannoxane etc. can be mentioned.

The addition amount of the curing accelerator is preferably 0.001 to 0.5 part by weight based on 100 parts by weight of the total of the acrylic polyol and the polyisocyanate compound.

Furthermore, the primer coating material used in the present invention can be appropriately blended with conductive powder such as conductive carbon or graphite, if necessary.

In the present invention, the primer coating is preferably applied at a liquid temperature of less than 60 ° C., preferably 20 to 40 ° C. so that the film thickness when dried is 10 to 40 μm, particularly preferably 15 to 30 μm, and the temperature is room temperature. It is allowed to stand for 3 minutes or more, preferably 5 to 10 minutes.

After that, in a wet-on-wet condition, apply an intermediate coating for vehicle exterior panels, for example, alkyd-melamine resin coating for 15-40
It is preferable to apply a coating having a thickness of μm and bake at 130 to 150 ° C. for 15 to 30 minutes. Also, this intermediate coating may be omitted.

After that, perform a water test and apply a topcoat paint (polyester resin / melamine resin-based paint or 2-pack acrylic / urethane-based paint) to the specified film thickness, that is, 35μ for solid
m or more, 15 to 20 μm for 2 coat 1 bake metallic base (2C1B), 30 μm for clear coat coating
Paint as above and bake at 130-150 ℃ for 15-30 minutes or at 70-90 ℃ for 20-40 minutes to complete the coating. If desired, putty repair may be performed before the water research.

If the heat resistance of the FRP molded product is 140 ° C or less,
After applying the above primer and applying a urethane-based top coating material in a wet-on-wet state by the same method as above, baking may be performed at 140 ° C. or lower, particularly at 70 to 100 ° C. for 20 to 40 minutes.

The FRP molded article coated by the method of the present invention is a plastic reinforced with a reinforcing material such as glass fiber,
Examples of the plastic include unsaturated polyester resin, epoxy resin, phenol resin, silicone, melamine resin and the like.

For the coating, the coating means such as spray coating, brush coating and the like, which are commonly used in the coating of FRP molded products, can be used.

(Function) In the FRP molded article coating method of the present invention, since a two-component urethane resin-based coating material containing a tin compound as a curing accelerator is used as a primer, pinholes in the vicinity of the bonding surface and the surface of other portions are used. The coating film defect due to is prevented.

(Examples) Examples 1 to 6: Primer compositions containing acrylic polyol resin, pigment, polyisocyanate compound and tin compound in the blending amounts (parts by weight) shown in Table 1 below (Examples 1 to 6). Was manufactured.

Table 1 also shows the processing conditions of the primer coating and other processing steps, the type of paint, the test results, and the like.

In the table, acrylic polyol resin ¹⁾ is styrene / methyl methacrylate / hydroxypropyl methacrylate / hydroxyethyl acrylate / acrylic acid (15/59
/ 15/10/1 (weight ratio)), the hydroxyl value is 80, and the weight average molecular weight is 30,000. The pigment content ²⁾ is shown as the weight content (%) of each pigment in the cured coating film. The polyisocyanate compound A ³⁾ is a reaction product of hexamethylene diisocyanate and water, and the polyisocyanate compound B ⁴⁾ is a reaction product of xylylene diisocyanate and trimethylolpropane. Dibutyltin laurate was used as the tin compound ⁵⁾ . NCO / OH ⁶⁾ indicates the ratio of the isocyanate group in the polyisocyanate compound to 1 mol of the hydroxyl group in the polyol resin. The coating viscosity ⁷⁾ is adjusted with a mixed thinner consisting of toluene / ethyl acetate / solveso (40/30/30 (weight ratio)). Further, TA in the column of top coat paint indicates a polyester resin / melamine resin type paint, and TB indicates a two-component acrylic / urethane type paint.

The above primer composition is prepared by uniformly mixing and dispersing an acrylic polyol resin and a pigment as a base component, then mixing a polyisocyanate compound as a curing agent with the base component, and further adding a tin compound as a curing accelerator. It was manufactured by adding a solvent and adjusting the coating viscosity. The solid content of each of the compositions was 40 to 50% by weight.

500 cc of each of these primer compositions was put into a glass bottle until about 7 minutes, and the composition was sealed and stored, and the time until the viscosity was increased to 20 seconds / 20 ° C. in Ford cup # 4 was measured. The performance (pot life) of the primer composition itself was examined. The results are shown in Table 1.

Using the above primer composition, FRP was prepared as follows.
The molded product was painted. As the FRP molded product, an SMC (Sheet Molding Compound) molded product having an adhesive structure was used. First, secondary processing including deburring, sanding, adhesion, scraping of adhesive, repair of putty, and water research (however, only repair of putty of Example 1) was performed to manufacture a secondary processed product. After degreasing this, the primer composition prepared above is spray-coated so that the film thickness when dried is 15 to 30 μm while adjusting the liquid temperature to 20 ° C to 40 ° C, and then at room temperature. Let stand for 3-10 minutes. Wet-on-wet intermediate coating for car body panels (alkyd-melamine resin-based coating) is applied to this to a dry film thickness of 15-40 μm, and the temperature is 130-150 ° C for 15-30 minutes. Baked (except for Example 2). Then, putty repair was performed again about Examples 1-3. Then, after sanding with sandpaper, draining and drying, the topcoat paint was applied to a thickness of 35 to 40 μm based on the cured coating film. Polyester resin / melamine resin-based paint (T
A) or a two-component acrylic / urethane-based paint (TB) is used and TA is used, 130 ℃ ~ 150
The coating was completed by baking for 15 to 30 minutes at ℃. Also, TB
In the case of, the coating was completed by baking at 70 to 90 ° C for 20 to 40 minutes after coating. For each of the obtained coated products, the effect of preventing coating film defects was evaluated by counting the number of pinholes in the vicinity of the adhesive surface and the surface of other portions. Pinhole
Diameter 200-600 μm (large in the table), diameter 70-200
The measurement was performed for each of those having a diameter of 10 μm (in the table, middle) and those having a diameter of 10 to 70 μm (small in the table). The appearance of the coating film and the adhesion of the coating film were also evaluated, and the results are shown in Table 1. Regarding the adhesiveness, use a single-edged razor and make a grid of 2 mm intervals on the surface of the test plate.
Make 100 pieces, and cellophane adhesive tape (JIS Z 1522) on it
Was fully pressure-bonded, peeled off at once in the 90 ° direction, and the state of surface peeling was examined to evaluate. Further, the reduction rate of the repair was examined with respect to the method of performing the putty repair (reduction rate 0%) both at the time of the secondary processing and after the intermediate coating, and is shown in Table 1.

Comparative Examples 1 to 3 For comparison, a primer composition (Comparative Examples 1 to 3) containing an acrylic polyol resin, a pigment and a polyisocyanate compound in a blending amount (parts by weight) shown in Table 1,
It was manufactured according to the method of Examples 1 to 7 except that no tin compound was added. The performance (pot life) of the obtained primer composition itself was examined. The results are shown in Table 1.

An SMC molded product similar to that of Example 1 was molded and coated by the same method as in Example 1. However, the presence or absence of intermediate coating and the presence or absence of repair of putty during secondary processing are as shown in Table 1. First, secondary processing consisting of deburring, sanding, adhesion, scraping of an adhesive, repair of putty (excluding Comparative Example 3) and water polishing was performed to manufacture a secondary processed product. The primer composition prepared above was applied thereto in the same manner as in Example 1, and then an intermediate coating for vehicle body outer panels (alkyd-melamine resin-based coating) was applied in a wet-on-wet state (Comparative Example 1). And 2 only), and then the top coating material was applied and baked under the same conditions as in Examples 1 to 6 to complete the coating. The pinhole stopping effect, coating film appearance, and adhesiveness of the obtained coated product were measured by the same methods as in Example 1. The results are shown together in Table 1.

(Effects of the Invention) When a molded product having an adhesive structure is coated by the FRP molded product coating method of the present invention, there is no defect due to pinholes even in the vicinity of the bonded surface, and the appearance of the entire molded product is very good. An excellent coated product can be obtained. Therefore, it is possible to greatly reduce the number of man-hours that have been spent until now for repairing defects such as pinholes. In addition, the labor and cost for painting can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of an embodiment of a method for coating an FRP molded product.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Ishii, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor, Yoshinori Tsuchiya, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation ( 72) Inventor Kazuyasu Hanai 14th Osawa, Fukutani, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture Uchihama Industry Co., Ltd. In-house (72) Inventor Mitsunori Yamada, 14th Osawa, Fukutani, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture Uchihama Industry Co., Ltd. (72) Inventor Michio Tanaka 2-14-13 Mihara, Ibaraki City, Osaka Prefecture

Claims (1)

[Claims] 1. A FRP molded article is coated with a two-component urethane resin coating comprising an acrylic polyol and a polyisocyanate compound, to which a tin compound is added, as a primer coating at a liquid temperature of less than 60 ° C. How to paint FRP molded products.