JPS6099140A - Coating composition for polypropylene molded article - Google Patents

Abstract

PURPOSE:To provide a composition obtained by compounding a chlorinated isotactic polypropylene, an ethylene-vinyl acetate polymer, an isocyanate compound and a solvent, having extremely excellent heat-resistance, adhesivity and chemical resistance, and suitable as an undercoating agent. CONSTITUTION:The objective composition can be produced by compounding (A) 100pts.(wt.) of a chlorinated isotactic polypropylene having a chlorine content of 15-35(wt)%, preferably 20-30% with (B) 10-200pts. of an ethylene- vinyl acetate copolymer having a vinyl acetate content of 25-40%, (C) 1-50pts. of an isocyanate compound and (D) a solvent capable of dissolving the above components. The component C is a polymeric polyisocyanate compound, preferably condensate of purified methylene diphenyldiisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition for coating polypropylene molded articles. More specifically, the present invention relates to a coating composition that can be used as an undercoat or paint vehicle to facilitate painting on polypropylene molded articles, or as an adhesive.

Conventionally, since polypropylene is non-polar and crystalline, ordinary coating compositions hardly adhere to it, so it has not been possible to paint the surface of molded products or assemble molded products by gluing them together with adhesives. Have difficulty.

Therefore, the adhesion of paint to the surface of polypropylene molded products,
In order to improve adhesion, the surface of the polypropylene molded product is subjected to surface treatments such as corona discharge treatment, flame treatment, or hot potassium dichromate/sulfuric acid mixture treatment, which oxidizes the surface and introduces polar groups. was taken.

However, although such a method is effective in improving adhesion, it is difficult to apply depending on the shape of the object to be coated, and has drawbacks in terms of workability and cost.

On the other hand, attempts have been made to create coating compositions that do not require such pretreatment and have adhesion to polypropylene surfaces. For example, compositions made of aromatic petroleum resin and cyclized rubber, compositions made of cyclized rubber and rosin or rosin derivatives, modified alkyds, compositions made of acrylic resin and chlorinated polypropylene resin have been proposed. However, it has insufficient adhesion to untreated polypropylene molded products, and has drawbacks in weather resistance, gloss, chemical resistance, etc., and is subject to practical limitations.

In addition, compositions consisting of chlorinated isotactic polypropylene and ethylene-vinyl acetate copolymer resin, compositions in which an inorganic filler and petroleum resin are added to the former two components, and compositions in which a phenolic resin is added to the former two components are available. Proposed.

However, they similarly have drawbacks in terms of adhesion, chemical resistance, heat resistance, cost, etc.

Therefore, the present inventors conducted intensive research to improve the chemical resistance and heat resistance of polypropylene without impairing its adhesion, and found that isocyanate was added to chlorinated isotactic polypropylene and ethylene-vinyl acetate copolymer resin. It has been found that by adding a compound, a product having extremely excellent heat resistance, adhesion properties, and chemical resistance can be obtained.

To describe the present invention in more detail, ethylene-
As an undercoat or paint vehicle for easy painting of polypropylene molded products, consisting of 10 to 200 parts by weight of a vinyl acetate copolymer resin, 1 to 50 parts by weight of an isocyanate compound, and a solvent for dissolving these, or as an adhesive. The present invention relates to a coating composition as a coating agent.

The chlorinated isotactic polypropylene and the isocyanate compound contribute to the adhesion and adhesion of the composition obtained by the present invention to polypropylene, and the adhesion to the top coat is due to the ethylene-vinyl acetate copolymer resin and the incyanate compound. The isocyanate compounds are also intended to improve the cohesive strength of the coating. The mechanism by which isocyanate groups improve cohesive force is not clear, but for acid-modified chlorinated isotactic polypropylene or chlorinated isotactic polypropylene with hydroxyl groups introduced, isocyanate groups and active hydrogen It is thought that it reacts and increases cohesive force.

Further, in chlorinated isotactic polypropylene, the hydrogen atoms in the carbon-hydrogen bond adjacent to the carbon-chlorine bond tend to move freely, and this seems to be because this hydrogen reacts with the isocyanate.

The chlorinated isotactic polypropylene used in the present invention has a chlorine content of 15 to 35% by weight, preferably 2% by weight.
0 to 30% by weight of low chlorinated isotactic polypropylene is preferred. The ethylene-vinyl acetate copolymer resin preferably has a vinyl acetate content of 25 to 40% by weight. As the incyanate compound, an isocyanate compound as a raw material for ordinary polyurethane is used, but preferably a polymeric polyisocyanate metal compound, methylene diphenyl diisocyanate (MDI) is used.
) is most preferred. Examples of such substances include polymeric isocyanate (Millionate MR, Nippon Polyurethane Co., Ltd.), polymethylene polyphenyl in cyanate (PAPI, Up Jo
Examples include polyisocyanate compounds such as Polymeric Polyisocyanate (PP Co., Ltd., Mobay Co., Ltd.) and Polymeric Polyisocyanate (PP Co., Ltd., Mobay Co., Ltd.). Examples of solvents include aromatic solvents such as toluene and xylene, carbon tetrachloride, trichloride, and propylene dichloride.

Chlorinated solvents such as monochlorobenzene, 0-dichlorobenzene, and P-dichlorobenzene are used. The solvent has a solution concentration of 30% by weight or less, preferably 5 to 15% by weight.
It is used in a range of % by weight.

The polypropylene molded article coating composition of the present invention is easily prepared by adding an isocyanate compound to a solution in which chlorinated isotactic polypropylene and ethylene-vinyl acetate copolymer resin are dissolved. Similarly, if necessary, it can be adjusted by mixing stabilizer 1, coloring pigment, 9 extender pigment, and other additives.

When the composition of the present invention is used as an undercoat, suitable topcoats include urethane resin paints, epoxy resin paints, acrylic resin paints, and aminoalkyd resin paints.

Furthermore, the composition of the present invention is not only used as an undercoat paint for polypropylene molded articles, but also widely used as a binder for coating materials such as top coat paints, adhesives, and printing inks.

The examples described below serve to better explain the invention and are not intended to limit the scope of the invention. It should be noted that all percentages and parts shown in the examples are based on weight.

[Example 1] Chlorinated polypropylene (c
p-343-1, manufactured by Eastman Chemical Products Co., concentration 50% by weight, chlorine content 19% by weight) 200 parts by weight and 100 parts of ethylene-vinyl acetate copolymer (vinyl acetate content 28% by weight 1M = 18) Dissolve parts by weight of polymeric polyisocyanate compound (Mione) MR.
-200, manufactured by Nippon Polyurethane Co., Ltd.) at 5 parts by weight and 10 parts by weight per 100 parts by weight of the solid content of chlorinated boropropylene, and mixed to form a uniform solution with a film thickness of 10 to 10 parts by weight.
Apply Shangkanji's solution (primer) to a thickness of 15 μm and dry at room temperature for 1 hour.

On the other hand, commercially available chloroprene-based adhesive culm j is applied by brushing onto a No. 9 canvas 2 to 3 times per hour. After 30 minutes, it is combined with a polypropylene plate coated with a primer and pressed with a roller. After 48 hours, it was cut into test pieces of 15ffiX 2.5 cm, heated to 180°C, and tested*2.

The results are shown in Table 1.

[Comparative Example 1] A primer solution was prepared according to Example 1 without adding the polymeric polyisocyanate compound, and the same test was conducted. The results are shown in Table 1.

Table 1180° exposure test results *1 Polypropylene resin, Showa Yuka MA410 11
Injection molded plate with a size of crr1 x 15crn *2 Autograph 5-sooo (manufactured by Shimadzu Corporation)
1 in a constant temperature and humidity room (23℃, RH 55cm) using
An 80° rotation test was conducted. cross head speed t
' 300 ms/*3 A: Interfacial failure between polypropylene plate and primer C Cohesive failure of primer [Example 2] According to Example 1, a solution of chlorinated propylene and ethylene-acetic acid vimena W-combined A polymeric isocyanate compound (Millionate MR-200, manufactured by Nippon Polyurethane Co., Ltd.) was added to a solid content of 10% of chlorinated polypropylene.
5 parts by weight were added to 0 parts by weight to form a uniform solution.

The above solution (primer) was applied to a polypropylene plate whose surface had been cleaned with toluene to a film thickness of 10 to 15 μm, dried at room temperature for 1 hour, placed in a hot air dryer, and heated at 120°C for 10 minutes. Heat treatment was performed for minutes.

Then, on the above-mentioned polypropylene plate coated with the primer, apply acrylic lacquer (Koroku≠927 White, manufactured by Rock Paint Co., Ltd.) using a Ford cup +4 to adjust the viscosity to 15 seconds (20°C) K, and use a spray gun. Then, paint the film to a thickness of 50μ, and apply it for 24 hours.
After standing for a period of time, it was dried and cured at 80° C. for 30 minutes.

Table 2 shows the performance of the resulting coating film.

[Comparative Example 2] A test similar to Example 2 was conducted without using the polymeric isocyanate compound.

Table 2 shows the performance of the resulting coating film.

[Example 5] 800 parts by weight of toluene, 100 parts by weight of chlorinated polypropylene (Birdren 15LLB, chlorine content 30% by weight, manufactured by Toyo Kasei Kogyo Co., Ltd.) and ethylene-vinyl acetate copolymer, (vinyl acetate content 28% by weight) %9M engineering: 1B)
100 parts by weight was dissolved, and 5 parts by weight of a polymeric polyisocyanate compound (Millione MR-200, manufactured by Nippon Polyurethane Co., Ltd.) was added to 100 parts by weight of the solid content of the chlorinated polypropylene to form a uniform solution.

A similar test was conducted according to Example 2.

Table 2 shows the performance of the resulting coating film.

[Comparative Example 3] A test similar to Example 5 was conducted without using the polymeric polyisocyanate compound.

Table 2 shows the performance of the resulting coating film.

Table 2 Physical properties of coating film ○: No abnormality Δ: Slight abnormality observed was left in a blow dryer at 80° C. for 48 hours, and 1 hour after taking it out, a board durability test was conducted.

Patent applicant: Toyo Soda Kogyo Co., Ltd.

Claims (3)

[Claims] (1) 100 parts by weight of chlorinated isotactic polypropylene with a chlorine content of 15 to 35% by weight. 10 to 200 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 25 to 40 parts by weight. A composition for coating polypropylene molded articles, comprising 1 to 50 parts by weight of an isocyanate compound and a solvent capable of dissolving the above compound. (2) The composition according to claim 1, wherein the incyanato compound is a polymeric polyisocyanate compound. (3) The composition according to claim 2, wherein the polymeric polyisocyanate compound is a purified and pretreated condensate of methylene diphenyl diisocyanate.