JPH0765005B2 - Primer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a primer composition, particularly a plastic primer composition suitable for an olefin elastomer resin.

(Problems to be Solved by Conventional Techniques and Inventions) Conventionally, as a primer composition for plastics, for example, there is a primer for an olefin resin mainly containing chlorinated polyolefin and partially containing a urethane resin or a pigment. . However, such a conventional primer composition for plastics has a glass transition point (hereinafter referred to as Tg) of the primer.
Is about 0 ° C., and the composition is very brittle at temperatures below this, and the elongation of the coating film decreases. For this reason, topcoat paints (Tg: 48
However, there is a problem in that the bending elasticity of the plastic coating object is controlled by the physical properties of the coating film at low temperature (-20 ° C or less) when coated at -50 ° C).

(Means for Solving Problems) In the present invention, a modified ethylene-propylene copolymer grafted with maleic acid or its anhydride as Component A, Component B
Chlorinated ethylene-vinyl acetate copolymer as the component and melamine resin as the component C, and each of these components in a specific range, that is, the ratio of the component A and the component B in the solid content weight ratio is component A / component B = 90. / 10 to 20/80, and a composition containing Component C in a solid content weight ratio of (Component A + Component B) / Component C = 100/5 to 100/40. This is a solution to the above problems.

In the above-mentioned primer composition of the present invention, the modified ethylene-propylene copolymer obtained by grafting maleic acid or its anhydride as the component A is obtained by grafting maleic acid or maleic anhydride on the ethylene-propylene copolymer. Is a copolymer with a graft amount of 0.1 to 50 PHR
(Parts by weight / 100 parts by weight of resin), preferably 0.3 to 20 PHR. The ethylene-propylene copolymer which is a raw material of the modified copolymer (A) is a copolymer of ethylene and propylene, and the content of propylene is 50 to 70 mol%, preferably
It is in the range of 60 to 70 mol%.

When the amount of maleic acid or its anhydride used in the modified copolymer (A) is less than 0.1 PHR, the adhesion to the primer composition and the top coating material is insufficient, and the solubility in organic solvents also decreases. On the other hand, if it exceeds 50 PHR, the water resistance of the coating film becomes poor. Further, if the content of propylene in the ethylene-propylene copolymer is less than 50 mol%, the solvent resistance of the coating film is poor, and if it exceeds 75 mol%, the solubility in an organic solvent decreases,
Adhesion to the material of the coating film and the topcoat paint is reduced.

The method for grafting maleic acid or its anhydride onto the ethylene-propylene copolymer should be carried out using a conventionally well-known method, for example, the method described in JP-A-55-43260. You can

The chlorinated ethylene-vinyl acetate copolymer which is the component B in the present invention has a chlorine content of 10 to 30% by weight and a weight average molecular weight.
100,000 to 300,000 and chlorinated ethylene / vinyl acetate (solid content weight ratio) 90/10 to 50/50, for example, trade names "Super Clone A" and "Super Clone B" (both Sanyo Kokusaku Pulp) Manufactured). Chlorinated ethylene
If the chlorine content in the vinyl acetate copolymer (component B) is less than 10% by weight, it becomes incompatible with the solvent, while if it exceeds 30% by weight, the hardness of the coating film increases and the physical properties at low temperatures (impact resistance, bending resistance) are increased. Sex) is reduced. If the weight average molecular weight of component B is less than 100,000, the low temperature physical properties are reduced as above, while if it exceeds 300,000, atomization of component B is difficult and the coating workability is reduced.
Also, the solid content weight ratio of chlorinated ethylene / vinyl acetate is 90.
When it is larger than / 10, compatibility with the solvent is deteriorated, and when it is smaller than 50/50, low temperature physical properties are deteriorated.

As the melamine resin which is the component C in the present invention, for example, isobutylated melamine resin (trade name “Super Beckamine L-116-30” manufactured by Reichholt Japan Ltd.) and butylated melamine resin (trade name “melamine” are commonly used. 2000 "manufactured by Hitachi Chemical Co., Ltd.), but any other melamine resin may be used as long as it is not butylated or isobutylated.

In the composition of the present invention, the above-mentioned component A and component B
Is the ratio of both components in terms of solid content weight ratio: component A / component B = 90/1
Mix in the range of 0 to 20/80, preferably 70/30 to 40/60. When component A / component B exceeds 90/10, low-temperature flexibility and low-temperature impact resistance deteriorate, whereas component A / component B contains 20/8
When it is less than 0, the adhesion and hot water resistance of the coating film are deteriorated. Further, the component C is contained in a weight ratio of solid content of (component A + component B) / component C = 100/5 to 100/40, preferably 100/10 to 20.

In this case, when (Component A + Component B) / Component C exceeds 100/5, low temperature flexibility and low temperature impact resistance are improved, but hot water resistance decreases, whereas when less than 100/40, hot water resistance is reduced. Is improved, but low temperature flexibility and low temperature impact resistance are decreased. For this reason, in the present invention, the components A, B and C are
Should be contained within the above specific range.

Further, the composition of the present invention may contain the following components in addition to the above components A, B and C, if necessary.

Pigments: Organic and inorganic pigments such as titanium dioxide, carbon black, Shanin Blue, extender pigments: talc, kaolin, barium sulfate, calcium carbonate, etc. Conductive pigments: conductive carbon black, solvents: use of all organic solvents Other additives: Silicon-based and non-silicon-based additives, UV adsorbents, antioxidants, antistatic agents, acrylic surface conditioners, amide-based or polyolefin-based waxes, etc. .

In this case, P / B is preferably 2.5 or less, where B (vehicle) is the total solid weight of the components A, B and C and P (pigment) is the total weight of the pigment. If this P / B exceeds 2.5, the viscosity of the coating material becomes high, so the workability is significantly reduced, and the coating performance such as adhesion and moisture resistance is also reduced. In addition, the finish appearance of the topcoat paint also deteriorates.

The solvent is used only for the purpose of diluting the basic resin and the pigment, and there is no problem in performance, so that the solvent can be mixed in any proportion. Further, the above-mentioned other additives can be mixed, if necessary, within the range generally used.

The primer composition of the present invention is prepared by mixing each of the components A, B and C in the above specified range, and optionally the above other components, and using a ball mill, roll mill, attritor, It can be performed by uniformly mixing and dispersing using a dissolver or the like. Also,
The coating of the primer composition thus prepared on a steel plate or a plastic material constituting an automobile body can be carried out by a generally known method such as spray coating, dip coating or roll coater method. The coated primer composition can be applied by a usual drying means such as natural drying or heat drying.

(Effects of the Invention) As described above, the primer composition of the present invention comprises a modified ethylene-propylene copolymer (component A) grafted with maleic acid or an anhydride thereof, a chlorinated ethylene-vinyl acetate copolymer (component B). ) And a melamine resin (component C) in a specific range, the notch of the top coating film at a low temperature of the plastic coated article coated with the top coating composition after the primer coating according to the present invention is applied. It is possible to prevent an effect (a phenomenon in which stress concentration occurs in a coating film crack caused by impact or bending, and the coating film crack serves as a notch to cause a crack in the material), and good elasticity can be maintained even at a low temperature. In addition, this good performance can be fully exhibited even if the primer film thickness is 5 to 8 μm, which is extremely thin compared to the conventional primer film thickness of 15 to 20 μm. Is less likely to be affected, and thus the image clarity of the top coat film can be improved as compared with the conventional case.

<Test 1> (Examples 1 to 15) and (Comparative Examples 1 to 13) In the primer composition ratios shown in Table 1 (Examples) and Table 2 (Comparative Examples), only components A, B and C, or Other components were added to and mixed and dispersed in toluene sufficiently uniformly by a usual means to prepare a primer composition of the present invention and a primer composition for comparison.

The primer composition thus prepared was applied to olefin elastomer resin parts (trade name: Lavalon NRO4 manufactured by Mitsubishi Yuka Co., Ltd.) that had been washed and degreased with 1,1,2-trichlorotrifluoroethane, and then this Wet-on-wet (2 minutes left at room temperature) on the primer coating film for resin top coating (manufactured by NOF CORPORATION) Trade name: PLUGROS # 30
00) was applied and baked at 120 ° C. for 30 minutes to prepare test samples (Examples 1 to 15 of the present invention and Comparative Examples 1 to 13). Various coating film performance tests were conducted using the test samples, and the test results are shown in the lower part of Tables 1 and 2. In the test results, ⊚ indicates excellent, ∘ indicates good, Δ indicates practically acceptable, and × indicates defective.

As is clear from Tables 1 and 2, the primer composition of the present invention in which the components A, B and C were blended in a specific range did not have a functional group capable of reacting with the melamine resin in the components A and B, but the reactivity was high. By adding the melamine resin (component C), the components A and B form an apparent crosslinked structure and impart elasticity to the primer coating film, so that the coating performance is superior to the comparative primer. You can see that

<Test 2> In Table 3, P / B described above using the components A, B and C within the scope of the present invention is shown.
The test results for the appearance and moisture resistance of the top-coat paint when the value is changed are shown. It can be seen that the blending ratio of the pigment component contained in the plastic primer composition of the present invention is preferably P / B of 2.5 or less.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C09D 151/06 PGX 161/28 PHK (72) Inventor Kazuo Kakinuma 4536 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture -26 Tomioka Heights A-204 (72) Inventor Shosaku Yamamoto 1-32-12 Motoohashi, Totsuka-ku, Yokohama-shi, Kanagawa

Claims (1)

[Claims] 1. A component A: a modified ethylene-propylene copolymer grafted with maleic acid or an anhydride thereof, a component B: a chlorinated ethylene-vinyl acetate copolymer, and a component C: a melamine resin. And component B in a ratio of solid component weight ratio of component A / component B = 90/10 to 20/80, and the component C in solid component weight ratio of (component A + component B) / component C. = 100/5 to 100/40 contained in the primer composition.