JPS6189235A - Coating method for olefin resin molded products - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for coating olefin resin molded articles.

More specifically, after obtaining an olefin resin molded product by air pressure molding, extrusion molding, injection molding, etc., a resin composition consisting of a modified olefin polymer and a polyolefin, the surface is pretreated and an undercoat is applied. without doing,
This invention relates to a method of applying top coat paint (urethane paint).

Polyolefins have excellent mechanical properties such as rigidity and tensile strength, as well as excellent chemical resistance and processability.
It is used for a wide range of purposes. However, since polyolefin is a non-polar lrimer, it does not have good adhesion to food, and in the case of urethane paints, there is a problem in that it does not adhere at all without an undercoat.

In order to solve these problems, the inventors of the present invention have made extensive studies and have found a method of achieving good adhesion between an olefin resin and a urethane paint even without an undercoat, leading to the present invention.

That is, a crystalline and/or rubbery copolymer of ethylene and propylene having an ethylene content of 10 to 80% by weight, or a crystalline and/or rubbery copolymer of these and an olefin having 4 or more carbon atoms, is mixed with 0.1 to 0.1 to 0.1% of an unsaturated dicarboxylic acid or its anhydride. 0.1 to 70 parts by weight, preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight of a modified copolymer obtained by graft copolymerizing 10% by weight, and 99.9 to 8 parts by weight of polyocyanin, preferably 99 to 8 parts by weight. The surface of the molded article of the resin composition containing 50 parts by weight, more preferably 95 to 60 parts by weight, is not pretreated at all, or pretreatment methods include treatment with halogenated hydrocarbons, degreasing treatment with aqueous alkaline solutions, aromatic After performing at least one pretreatment selected from degreasing treatment with hydrocarbons and aliphatic alcohols,
The present invention relates to a method for coating an olefin resin molded article, which comprises coating the surface with a urethane paint.

The raw materials for the modified copolymer used in the present invention are ethylene and propylene with an ethylene content of 10 to 80% by weight, or crystallinity and/or combination of these and an α-olefin having 4 or more carbon atoms.
Or a rubbery copolymer.

The crystalline and/or rubbery copolymer includes block PP and ethylene-propylene rubber (EP rubber). In addition, some EP rubbers include ethylene rubber and ethylene-propylene-nonconjugated diene copolymer (E
PDM) is included.

Examples of the α-olefin having 4 or more carbon atoms include eva, phthene-1, pentene-1, hexene-1,4-methylpentene-1, octene-1, and the like.

The modified polymer used in the present invention can be obtained by a known method such as adding the above-mentioned aggregates and a radical generator, stirring and heating, or supplying each of the above components to an extruder and performing graft copolymerization. I can do it with Jin.

Examples of the unsaturated dicarboxylic acid or its anhydride used to prepare the modified copolymer include maleic acid, himic acid, itaconic acid, maleic anhydride, himic anhydride, itaconic anhydride, and the like.

This is not preferable because it lowers the modification weight in the resin composition used in the present invention.

If one or more polyalcohols selected from the group consisting of trimethylolpropane, 1°6-hexanediol, pentaerythritol, and dipentaerythritol are added to the resin composition as necessary, the paintability can be further improved. There is.

In addition, if necessary, styrene elastomers such as styrene-butadiene random copolymers and styrene-butadiene block copolymers, various fillers such as glass fiber, talc, wood flour, and calcium carbonate, antioxidants, and weather-resistant It can be used by adding additives such as agents.

Typical polyolefins used in the present invention include polyethylene, +j? Examples include lipropylene, ethylene-propylene copolymer, propylene-ethylene-butene terpolymer, ethylene-butene copolymer, polybutene-1, and combinations thereof.

Pretreatment in the present invention is not performed at all, or treatment with halogenated hydrocarbon solvent, low temperature plasma treatment, corona discharge treatment, flame treatment, alkaline degreasing treatment,
At least one method selected from degreasing treatment using aromatic hydrocarbons or aliphatic alcohols is used.

In the treatment with a halogenated hydrocarbon solvent, the halogenated hydrocarbon solvent as a pre-treatment agent is not at all preferable in terms of the working environment, but it has many desirable points such as being flame retardant or noncombustible and having little risk of fire. Examples of halogenated hydrocarbon solvents include methylene chloride, chloroform, carbon tetrachloride, 1,1.1-)lychloroethane, 1.1.2°2
-Tetrachlorethylene, trichlorethylene, perchlorethylene, methylene bromide, bromoform, Freon IB, Freon BF and the like.

Methods for this surface treatment include steaming with halogenated hydrocarbon vapor, wiping with the same solvent, or immersion, but methods that are easier to achieve a homogeneous work include immersing the molded product or steaming the surface with steam. This is desirable.

Preferably at 60-100°C in a halogenated hydrocarbon solvent.
The polyolefin resin molded product is immersed for 5 to 120 seconds, or the surface of the molded product is washed with steam. More preferably, the above treatment is carried out at 70 to 90°C for 15 to 60 seconds. The low-temperature plasma treatment is performed by exciting a gas such as oxygen, nitrogen, argon, helium, etc., preferably oxygen, at a pressure of 1 (la + Hf or less, preferably 0.1 to 1.0W, 111HjF) by discharge such as glow discharge or high-frequency discharge to generate low-temperature plasma. This is a method in which the molded product obtained by molding a polyolefin resin is placed in this atmosphere and subjected to the plasma treatment, and the treatment strength requires that the surface wetting tension of the treated object immediately after treatment is 88 dynes/CM or more. If the treatment is less than that, the effect of the treatment on adhesion cannot be obtained.In addition, if the treatment is too strong, the surface of the polypropylene resin tends to decompose and the adhesive force decreases.

For this reason, the treatment strength is preferably such that the surface wetting tension of the surface to be treated is 88 dynes/c- or more and 65 dynes/c- or less, and more preferably 42 dynes/ca or more and 55 dynes/aa or less.

For alkaline degreasing, polyolefin molded articles are immersed in an alkaline aqueous solution, or the aqueous solution is applied to the surface by spraying or brushing, followed by washing with water and drying. Examples of the alkaline aqueous solution include aqueous solutions of metal silicate, metal phosphate, metal carbonate, caustic soda, caustic potash, etc., and aqueous solutions of metal silicate, caustic soda, caustic potash, etc. are preferred. pH of alkaline aqueous solution (hydrogen ion concentration)
It is preferable to carry out the treatment at 9 to 14, preferably 11 to 14. If the pH is below 9, the degreasing power is weak (and sufficient adhesion with urethane paints cannot be obtained).

However, to further enhance the effect, it may be pretreated with an alkaline aqueous solution, washed with water, dried, and then washed with a neutral detergent. Neutral detergents are conventional anionic or nonionic surfactants.

The method of wiping with a solvent is a method of wiping the surface of the molded article using an aromatic hydrocarbon or alcohol solvent, such as toluene or isopropyl alcohol.

In the above, no pretreatment is performed at all, or at least one method selected from treatment with a halogenated hydrocarbon solvent, low-temperature plasma treatment, corona discharge treatment, flame treatment, alkaline degreasing treatment, and solvent wiping is performed.

The paint used in the present invention is a flexible urethane-based paint, and examples thereof include acrylic urethane, polyester urethane, and other paints containing L-tan 4Ja.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 EPR containing 5% by weight of maleic anhydride (hereinafter abbreviated as MAR) was synthesized from ethylene-propylene rubber (hereinafter abbreviated as EPR) containing ethylene and R50Mfk% at 155°C in the presence of peroxide in a toluene solution. did. (This composite is hereinafter referred to as MAR-modified EPR-1) MAR-modified EPR-120 parts by weight and ethylene content of 7
．． Ethylene-propylene block copolymer (hereinafter referred to as block PP) 8 with a melt index of 8 at 4% by weight
0 parts by weight was kneaded and granulated using a twin-screw extruder manufactured by Ikegu Iron Works Co., Ltd.
Then, an injection molded plate of 150 x 90 x 2 fft was produced using an injection molding machine.

Either the molded plate is not pretreated or the following 8.
After various pretreatments were carried out, urethane paint Flexene #101 manufactured by Nippon Bee Chemical Co., Ltd. was spray-painted, and baked at 120° C. for 80 minutes to dry.

Pretreatment: Steam with i, t, t-trichloroethane vapor at -074°C for 80 seconds.

(Hereinafter abbreviated as chlorocene treatment) Pretreatment - ■Sodium orthosilicate (Na
After soaking in Si04) aqueous solution at 60°C for 8 minutes with stirring, the sample is washed with water.

(Hereinafter, abbreviated as alkaline degreasing treatment) -■ Wiping the surface of the molded product with isopropyl alcohol (hereinafter, abbreviated as solvent wiping) The above-mentioned initial adhesion and water resistance of the coated plate were evaluated. The results are shown in Table-1.

(Notes) 1) Initial adhesion Evaluation of residual rate (%) in 2-shoe logo pan test using Nichiban Co., Ltd. 1R 24m wide Cellotape (registered trademark) (90° peeling) 2) Water resistance After immersion in 40℃ warm water for 240 hours, 1) As a result of the adhesion test, no peeling was observed in the cellophane tape peeling test with any pretreatment, and adhesion was observed even without a primer.

Comparative Example I Except for not adding MAR-modified EPR-1, as a result, as shown in Table 2, there was no adhesion at all.

Table 2 Comparative Example 2 of Coating Film Physical Property Evaluation Results Unmodified (unmodified) ethylene-propylene rubber (ethylene content 50% by weight. Hereinafter, unmodified EP
Coating evaluation was carried out in the same manner as in Example 1, except that the coating material (abbreviated as R) was used.

The results are shown in Table-3.

Table 8 Coating film physical property evaluation results Example 2 From EPR with 50 wt% ethylene content to EP containing 2 wt% MAH in toluene solution under peroxide catalyst at 156°C
Synthesized R. (This compound is referred to as MAR-modified EPR-
2) 280 parts by weight of the MAH-modified EPR-2 and 70 parts by weight of the PP used in Example 1 were mixed, granulated, and injection molded in the same manner as in Example 1 to obtain 150X90X:)
+wt injection molded plate was created.

After the molded plate was subjected to low-temperature plasma treatment as described below, it was spray-coated with urethane-based paint Flexene #101 manufactured by Nippon Bee Chemical Co., Ltd. in the same manner as in Example 1, and heated at 120°C.
, Baking for 80 minutes was followed by drying.

Low-temperature plasma treatment The molded plate surface was treated using a microwave plasma generator so that the surface wetting tension was 48 to 50 dynes/clI.

(Hereinafter, abbreviated as plasma treatment) The initial adhesion and water resistance of the coated plate were evaluated in the same manner as in Example 1, and no peeling was observed.

Example 8 The same resin composition as in Example 1 was used, except that polyester urethane paint R268 manufactured by Nippon B Chemical Co., Ltd. was used as the paint, and the resin composition was spray-painted and baked at 80° C. for 40 minutes to dry.
As a result of pretreatment and evaluation, no peeling was observed in any pretreatment.

Example 4 PP containing MAR 2% by weight was synthesized from a propylene-ethylene block copolymer having an ethylene content of 14% by weight and a melt index of 2 in a toluene solution at 165° C. in the presence of peroxide. (This composite is hereinafter referred to as MAH-modified PP) 80 parts by weight of the above MAR-modified PP and 70 parts by weight of PP having a melt index of 8 with an ethylene content of 16% by weight were mixed, granulated, pretreated, and mixed in the same manner as in Example 1. Painted and evaluated.

As a result, no peeling was observed.

Example 5 EPR with di-lene content of 50% by weight in toluene solution,
EP containing 0.5% by weight of L at 155 °C in the presence of peroxide.
R was synthesized (hereinafter referred to as MAE [modified EPR-
3).

The block PP with MAEI modified EPR-140 and ethylene content of 7.4% by weight and melt index of 8.
59 parts by weight was mixed, granulated, and molded in the same manner as in Example 1, and 1
An injection molded plate of 50×90×2 am t was made.

The molded plate was coated in the same process as in Example 1, baked and dried, and initial adhesion and water resistance were evaluated.

As a result, no peeling was observed.

Claims (1)

[Claims] A crystalline and/or rubbery copolymer of ethylene and propylene with an ethylene content of 10 to 80% by weight, or a crystalline and/or rubbery copolymer of these and an olefin having 4 or more carbon atoms, and 0.1 to 10% by weight of an unsaturated dicarboxylic acid or its anhydride. % graft copolymerized modified polymer and 99.9 to 30 parts by weight of polyolefin, the surface of the molded product is coated with a urethane paint. Painting method.