JPH0721073B2 - Primer composition for plastics - Google Patents

Description

TECHNICAL FIELD The present invention relates to a primer composition for plastic parts.

(Prior Art) Conventional plastic primers include, for example, (a) urethane lacquer primer, (b) acrylic urethane-based primer, (c) maleic acid-modified chlorinated polyolefin-based primer, (d) polyester-melamine-based primer, Etc.

(Problems to be Solved by the Invention) However, in the case of such a conventionally used primer, in the case of applying a primer coating for a car body having a hard coating film on the primer after applying the primer, A. When shocked at low temperature, the impact resistance of the coated resin is significantly lower than that of the uncoated resin material. B. Due to the above characteristics, mixing the conductive material into the primer promotes the reduction of impact resistance. there were.

(Means for Solving the Problems) This invention uses the composition of the primer A. propylene-ethylene-
A resin obtained by graft-copolymerizing maleic anhydride or maleic acid in an amount of 1 to 7% by weight with a butadiene copolymer, and B. containing one or more pigments. The above problems are solved by setting the total amount to 60% by weight or less, and 10 to 60% by weight when the pigment of the component B is conductive.

A first feature of the present invention is that a propylene-ethylene-butadiene copolymer graft-copolymerized with maleic anhydride or maleic acid is used as the resin.

The graft reaction of maleic anhydride or maleic acid can be carried out by a usual reaction method in which a propylene-ethylene-butadiene copolymer is reacted with a polymerization initiator such as benzoyl peroxide.

The amount of maleic anhydride or maleic acid grafted is 1 to 7% by weight. If it is less than 1% by weight, the adhesion to the top coating film is inferior, and if it exceeds 7% by weight, the viscosity of the coating material increases sharply and Not only is it difficult, but storage tests in the winter (5 ° C. or lower) crystallize into a gel, which is not preferable.

The number average molecular weight of the propylene-ethylene-butadiene copolymer maleic anhydride or maleic acid graft product is 3000.
˜120,000, preferably 15,000 to 50,000. 3000
If it is less than 1, the adhesion of the coating film is large, which is not preferable.
If it exceeds the range, the viscosity of the paint is high and the painting work becomes difficult, which is not preferable.

A second feature of the invention is the use of pigments, preferably conductive pigments. Examples of the conductive pigment include conductive carbon (for example, Ketjen Black EC, manufactured by Lion Akzo), conductive titanium oxide (for example, w-1, manufactured by Mitsubishi Metals Co., Ltd.) and the like.

As the primer coating film components A and B, the component A is 40% by weight or more and the component B is 60% by weight or less, but when the pigment of the component B is conductive, the resin of the component A is 40 to 40% by weight. 90% by weight, 10 to 60% by weight of the component B pigment. 10% by weight of pigment component
If it is less than 60% by weight, the problem of electrostatic workability remains, and if it exceeds 60% by weight, the problem of low temperature impact resistance remains.

In addition to components A and B, an organic solvent is used in the primer composition of this invention. The organic solvent is capable of dissolving the component A, and well-known organic solvents are used.

The primer composition is prepared by mixing the components A and B and mixing and dispersing them using a ball mill, a roll, an attritor, a dissolver or the like which is usually used for producing paints.

The primer composition is applied to the plastic material by a generally known method such as spray coating, dip coating and roll coater method. Drying of the primer composition may be either natural drying or heat drying. The thickness of the coating film thus formed is usually in the range of 3 to 50 μm.

(Experimental Example) Hereinafter, the present invention will be described with reference to Examples, Comparative Examples and Test Examples.

The resins A to C used in the examples were manufactured by the following method.

Resin A: Propylene 47.5% by weight, ethylene 47.5% by weight, butadiene 5% by weight, propylene-ethylene-butadiene copolymer having a number average molecular weight of 20000, 10% toluene solution 1000
g was charged into a two-necked four-necked flask equipped with a stir bar, a thermometer and a condenser, and the temperature was raised to 100 ° C. Thereafter, 3 g of maleic anhydride was added, and then 0.3 g of benzoyl peroxide was added, and the mixture was reacted under stirring for 3 hours. Next, 0.3 g of benzoyl peroxide was added and the reaction was carried out for 3 hours. After the reaction was completed, 30 g of toluene was added and the heating residue was adjusted to 10%.
Was synthesized.

Resin B: Resin B as in Resin A except that maleic anhydride 3 g was changed to maleic acid 7 g and benzoyl peroxide was changed to 0.7 g.
Was synthesized.

Resin C: Resin C was synthesized in the same manner as Resin A except that maleic anhydride was 9 g and benzoyl peroxide was 0.9 g.

Examples 1 to 4 and Comparative Example 1 A pigment shaker manufactured by Red Devil Co. was used to disperse the pigment to 5 μm or less over 2 hours,
The compounding ingredients shown in Table 1 are Nos. 1 to 3 and 5 of Examples 1 to 1.
The primer composition of No. 4 and the primer composition of Comparative Example 1 of No. 4 were prepared.

The storage stability of these compositions at -5 ° C is determined according to JIS K 54
The measurement was carried out according to the storage stability measurement method of 00 9.2, and the results are also shown in Table 1.

Test Example Next, as a means for improving impact resistance, modified polybutylene terephthalate (PB) prepared by blending 7 to 20% by weight of elastomer such as polybutadiene and ethylene propylene rubber (EPR).
T) Seven test pieces of 70 × 150 mm made of resin material were prepared. The test piece was thoroughly degreased with isopropyl alcohol, dried, and then coated with No. 1-5 primer to obtain a primer-coated test piece. Further, for comparison, urethane lacquer was applied and dried at 120 ° C. for 10 minutes, followed by No. 6 of Comparative Example 2.
The test piece of No. 7 in which the primer was not applied was used as the test piece of Comparative Example 3.

Next, OS-93 sealer (manufactured by Nippon Paint Co., Ltd.), which is a polyester-melamine intermediate coating, is applied onto the primer of the test pieces No. 1 to 5 by the wet-on-wet method. It was baked and dried at 30 ° C for 30 minutes. Next, polyester-melamine-based topcoat-solid Olga G-65 B326 White (manufactured by Nippon Paint Co., Ltd., trade name) is applied as the topcoat, and it is applied at 140 ° C for 3
It was baked and dried for 0 minutes. Table 2 also shows the dry film thicknesses of the primer, intermediate coating and top coating.

Further, the intermediate coating material and the top coating material were applied to the test pieces of Comparative Examples 2 and 3 in the same manner as described above, and the respective film thicknesses are also shown in Table 2.

Next, the following experiment was conducted on each of the coated plates, and the results obtained are shown in Table 2.

Evaluation method: (I) Low temperature impact resistance (i) HRIT (high rate impact test) RIT 8000 (test machine) manufactured by Rheometric Co., USA
(5/8 ″), holder diameter: 5 cm], and measure the state when the sample is punched by the hammer at a temperature of 30 ° C and a hammer speed of 11.1 m / sec.

○ …… The target penetrates the material (ductile fracture) △ …… The hole is larger than the target in the material (brittle fracture) × …… The material cracks or splits (brittle fracture) (ii) Deformed DuPont Type low temperature impact test By DuPont type impact test (Kamishima Seisakusho Co., Ltd.),
For each of the three test pieces under the following test conditions, sandwich the test piece with the coated surface facing upward between the shooting die and the pedestal.
Next, a weight with a specified weight is dropped from the specified height onto the shooting die, and the presence or absence of cracks in the coating film is displayed.

Temperature −30 ℃ Impact energy (weight × fall distance) 8kg × 2m ○ …… No film cracks, × …… film cracks (II) General performance (a) Appearance of coating Daylight color fluorescent lamp with 500 looks or more indoors Under certain conditions, a visual inspection is performed with normal vision from a position about 50 cm away from the surface to be inspected. However, coating defects such as blisters and pinholes may be made from a close range or from the licking direction.

○ …… Glossy value 90 or more (b) Adhesion Using a multi-cross cutter on the coating surface of the test piece, lightly reach the base material and draw parallel lines with equal intervals of 1 mm orthogonally to each other to make 25 squares of 1 mm square. . In this state, attach an adhesive tape with a sufficient width and peel it off at a stretch to check the number of squares on which the coated surface does not peel off.

○ …… No peeling of the coated surface (C) Humidity resistance Use a closed box that can adjust both temperature and humidity, and place the last piece horizontally in a closed box adjusted to a temperature of 50 ° C and relative humidity of 95% or more. After leaving for 24 hours, perform a tape peeling test.

○ …… No peeled coating surface, △ …… Blisters are generated (d) Heat resistance Place the last piece in a constant temperature bath at 90 ℃ for 500 hours, visually check the appearance, and measure the degree of yellowing ΔE.

○ …… ΔE3.0 (e) Gasoline resistance Test piece in regular gasoline at room temperature (20 ℃)
Immerse for 30 minutes, take out, leave for 24 hours, and then perform a first-eye tape peeling test.

○ …… No peeling of the coated surface (III) Conductivity Surface resistivity Put the electrode on the coated surface of the test piece and measure voltage (100V)
Set. Next, turn on the switch, read the pointer of the insulation resistance meter, read the surface resistance value, and pass 10 ⁸ Ω / cm ² or less.

(Effects of the Invention) As described above, in the plastic primer of the present invention, the propylene-ethylene-butadiene copolymer modified with a predetermined amount of maleic anhydride or maleic acid and the pigment are combined in a predetermined amount. By using it, the primer of the present invention, and the plastic parts coated with the topcoat paint, can be used without sacrificing the general performance of the paint such as paint appearance, paint adhesion, moisture resistance, heat resistance, and gasoline resistance. The effect that the impact resistance can be improved is obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Ueda 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. Bee Chemical Co., Ltd. (72) Inventor Akira Tokai Hayashi 2-14-1, Otani, Hirakata, Osaka Prefecture Nihonhon Bee Chemical Co., Ltd.

Claims (1)

[Claims] 1. A resin comprising a propylene-ethylene-butadiene copolymer graft-copolymerized with maleic anhydride or maleic acid in an amount of 1 to 7% by weight, and B. one or more pigments. The blending amount of component B is 60 of the total amount of components A and B.
A primer composition, characterized in that it is contained in an amount of not more than 10% by weight.