JP3220309B2 - Polyolefin molded body coated with non-yellowing primer for automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin molded article coated with a non-yellowing primer for automobiles.

[0002]

2. Description of the Related Art Conventional primers for polypropylene (PP) substrates include, for example, the following.
As the resin for the primer for the PP base material, a polyolefin resin or a chlorinated polyolefin resin having a similar solubility parameter (SP value) is applied in order to secure adhesion of the coating film to the PP base material. The polyolefin resin or the chlorinated polyolefin resin is modified with a compound having a polar group, such as epoxy or maleic anhydride, or is mixed with an epoxy resin in order to ensure adhesion to the top coat.

[0003]

However, in such a conventional primer for a PP substrate, an antioxidant, an ultraviolet absorber, a light stabilizer and the like are contained in the PP resin used as the substrate. And, because it is not a formulation that prevents the transfer of these additive components to the primer, in the case of light-colored topcoat, under the influence of heat, etc., the topcoat film turns yellow, lowering commercial value There was a problem.
Yellowing of the coating film, the hindered phenolic antioxidant contained in the PP base resin reacts with the chlorohydrin compound contained as a by-product of the epoxy resin used for the primer, and the yellowing degree increases. Hydrogen chloride generated by this dehydrochlorination reaction is a light stabilizer contained in the overcoat film, for example, the following formula

Embedded image Is reacted with the terminal N group of the 6-membered ring compound and further yellowed.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In a polyolefin molded article obtained by applying a primer and a top coat on a polypropylene base material, the present invention The present invention relates to a polyolefin molded article coated with a non-yellowing primer for automobiles, wherein a phosphorus-based antioxidant and a single hindered phenol-based antioxidant are added in combination. In the present invention, it is preferable to use a polyolefin resin or a chlorinated polyolefin resin and an epoxy resin as the resin for the primer.

[0005]

According to the present invention, a polyolefin resin or a chlorinated polyolefin resin and an epoxy resin are used as a primer, and a phosphorus-based antioxidant and a single-hindered phenol-based antioxidant contained as additives are phenol-based antioxidants. It has an excellent ability to reduce the quinone structure of the agent to a phenol type, and has a large yellowing improving effect. One-sided hindered phenolic antioxidant is a chlorhydrin compound which reacts with a chlorhydrin compound contained as a by-product of the epoxy resin used for the primer and a hindered phenolic antioxidant contained in the PP base resin. It has the function of preventing the quinone structure serving as a yellowing group from reacting first.
Further, the phosphorus-based antioxidant has a function of trapping hydrogen chloride generated by the dehydrochlorination reaction and further promoting the reaction of the simultaneously added hindered phenol-based antioxidant.
As a phosphorus antioxidant, alkyl phosphites,
Examples thereof include an alkylaryl phosphite type and a triaryl phosphite type.

[0006] One-sided hindered phenolic antioxidants include Sumilizer GA-80 manufactured by Sumitomo Chemical Co., Ltd., which has a large synergistic effect when used in combination with a phosphorus-based antioxidant or a sulfur-based antioxidant. can get. The amount of the phosphorus-based antioxidant and the one-sided hindered phenol-based antioxidant added to the primer together is 0.
It is preferably from 5 to 30% by weight. The addition amount of the phosphorus antioxidant and the one-sided hindered phenol antioxidant is 0.5
If the amount is less than 10% by weight, the reducing ability is insufficient, and the effect of preventing yellowing of the coating film is small. On the other hand, when the content exceeds 30% by weight, blisters (blister swelling) occur in the coating film after the water resistance test.

Further, the primer resin used in the present invention comprises a polyolefin resin or a chlorinated polyolefin resin and an epoxy resin, and the polyolefin resin or the chlorinated polyolefin resin has a polar group such as epoxy or maleic anhydride. Modified with a compound,
Alternatively, an epoxy resin is preferably mixed.
Adhesion to the substrate is ensured by a polyolefin resin having a similar SP value to that of the PP substrate, and adhesion to the top coat is ensured by epoxy or maleic anhydride having a polar group.

[0008]

The present invention will be described below with reference to examples and comparative examples. In the examples, parts represent parts by weight unless otherwise specified. Preparation of painted board Mitsubishi Yuka Co., Ltd. polypropylene (PP) base material (TX-
1180) was degreased using isopropyl alcohol. Next, Adecastab 2112 (manufactured by Asahi Denka Co., Ltd.) was used as a phosphorus-based antioxidant contained in the primer, and Sumilizer GA-80 (manufactured by Sumitomo Chemical Co., Ltd.) was used as a one-sided hindered phenol-based antioxidant. The primer was applied to a dry film thickness of 5 μm with the composition shown in (1), baked and dried at 90 ° C. for 20 minutes, and then a top coat (Sofflex # 1200 B621, manufactured by Kansai Paint Co., Ltd.) was dried. Is painted to be 30μm,
The coated plates of Examples 1 to 7 and Comparative Examples 1 to 3 were obtained by baking and drying at 120 ° C. for 20 minutes. Using this finished painted board,
A coating film performance test was performed by the following evaluation method.

Evaluation method (1) Heat-resistant yellowing A test piece is left in a drying oven maintained at 90 ° C. for 240 hours, and after one hour from the test piece, the b value is measured. The degree of yellowing (Δb) is calculated by the following equation. Δb = (b value after heat resistance test) − (b value before heat resistance test) Measuring device: CR-200 (manufactured by Minolta Co., Ltd.) (2) Adhesion of coating film A 2 mm gobang reaching the substrate using a cutter knife. Eye
Make 100 pieces (10 × 10), stick the adhesive tape on the goban eyes, and keep one end of the tape perpendicular to the effective surface.
The film is instantaneously separated at a speed of 5 m / s or more, and the adhesion of the coating film to the substrate is determined based on the number of peeled layers. (3) Water resistance Immerse the test piece in deionized water or distilled water. Place in a constant temperature water bath maintained at 40 ° C for 240 hours. After removal, and then left at room temperature for 1 hour, a coating adhesion test is performed. The adhesion test of the coating film is based on the above (2).

Table 1 shows the above evaluation results.

[Table 1]

[0011]

As described above, according to the present invention, in a molded polypropylene article obtained by applying a primer and a top coat on a polypropylene base material, the primer comprises a phosphorus-based antioxidant and a single hinder. Since a dophenolic antioxidant is used in combination and preferably added in an amount of 0.5 to 30% by weight based on the solid content of the primer resin,
An excellent effect of being able to prevent yellowing of the coating film due to heat was obtained, so that it was possible to expand the adoption of pale colors. In addition, inexpensive additives can be used, and the cost of the polypropylene substrate can be reduced.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Yamanaka, Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Kentaro Watanabe 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Isamu Hara 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-5-59327 (JP, A) JP-A-3-17459 (JP, A) JP-A-1-29455 (JP, A) JP-A-5-262965 (JP, A) JP-A-4-258643 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (3)

(57) [Claims] 1. A polyolefin molded article obtained by applying a primer and a top coat on a polypropylene base material, wherein a phosphorus-based antioxidant and a single hindered phenol-based antioxidant are used in combination for the primer. Polyolefin molded article coated with non-yellowing primer. 2. The method according to claim 1, wherein the phosphorus-based antioxidant and the one-sided hindered phenol-based antioxidant are based on the solid content of the primer resin.
2. A polyolefin molded article coated with a non-yellowing primer for automobiles according to claim 1, wherein the polyolefin is contained in a total amount of 0.5 to 30% by weight. 3. The polyolefin molded article coated with a non-yellowing primer for automobiles according to claim 1, wherein the resin of the primer comprises a polyolefin resin or a chlorinated polyolefin resin and an epoxy resin.