JP2608466B2 - Acid-curable coating composition for polyolefin resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for the purpose of protection or cosmetics of polyolefin resins, for example, polypropylene homopolymer, ethylene-propylene copolymer, ethylene-propylene, diene copolymer and the like. More specifically, the coating composition to be applied is overcoated or undercoated on polyolefin-based resin sheets, films and molded articles to give excellent coatings such as adhesion, weather resistance, moisture resistance, solvent resistance and appearance. The present invention relates to an acid-curable coating composition for a polyolefin resin.

[Conventional technology]

Polyolefin resin has excellent properties, such as chemical resistance, ozone resistance, heat resistance, good electrical properties, etc.
Since it is lightweight and inexpensive, it is widely used as an industrial material, such as home appliances and automobile parts, and is one of the materials that is expected to grow in demand.

However, while having such features, for example, in the case of automobile parts, the use of various types of plastics has been reduced from the viewpoint of energy saving, and the use of polyolefin-based resins has been increasing despite the increasing amount of use every year. Is only part. One of the reasons that hinders its general use is that the polyolefin resin is non-polar and crystalline, so that painting and bonding are difficult. Conventionally, printing or bonding to polyolefin resin has improved the adhesion by treatment such as corona discharge.However, these methods cannot perform uniform treatment on molded products with complicated surfaces. There is. Therefore, as a method of coating without these pretreatments, various primer compositions having good adhesion to polyolefin resins have been proposed. For example, cyclized rubbers disclosed in JP-B-49-18089, JP-B-49-5214,
Examples thereof include a primer composition comprising an aromatic petroleum resin, an oil-soluble phenol resin, a coumarone indene resin, and a chlorinated polyolefin. However, even if they have good adhesion to the polyolefin-based resin but insufficient adhesion to the topcoat, or show good adhesion to both the polyolefin-based resin and the topcoat, the solvent resistance is low. It has the drawback of poor properties. In particular, in recent years, a coating composition having gasoline resistance in addition to stronger adhesion and weather resistance has been required for a coating material used outdoors such as an automobile and a motorcycle. These include those obtained by copolymerizing a chlorinated polyolefin and a basic nitrogen-containing acrylic monomer and other acrylic monomers with an epoxy resin as a curing agent, as disclosed in JP-A-56-50971. , JP 59
JP-A-75958, JP-A-60-223831, tertiary amines are added as an accelerator to a carboxylated chlorinated polyolefin, and an epoxy resin is used as a curing agent; Japanese Patent Application Laid-Open No. 62-18434 proposes a compound obtained by copolymerizing a chlorinated polydiene, a chlorinated polyolefin and a hydroxyl group-containing acrylic monomer with a polyisocyanate as a curing agent. These are certainly excellent in adhesion to polyolefin-based resins, solvent resistance, and other physical properties. However, since they are two-part curable compositions in which the main component and the curing agent are mixed immediately before use, the curing agent is used. Has a drawback in that it has a so-called pot life from the point of time when the curing reaction progresses to a point where the coating becomes difficult due to the progress of the curing reaction to some extent, and is greatly restricted in the working time.

[Problems to be solved by the invention]

The disadvantages of the composition having a pot life are that not only are the working times significantly restricted, but also, for example, at the end of painting or printing, the remaining composition must be discarded before curing, and the A need arises to thoroughly clean the printing equipment and lines.

The present invention relates to a one-component polyolefin resin which has excellent adhesion, weather resistance, moisture resistance, appearance, etc., has excellent solvent resistance, and improves the disadvantages of a two-component curable composition. The present invention provides a novel and useful acid-curable coating composition having no pot life, which can be handled by the above method.

[Means for solving the problem]

The present inventors have solved the above-mentioned problems by reacting the hydroxyl-containing chlorinated polyolefin and the alkyl etherified amino resin in the presence of an acidic catalyst at room temperature without heating, and by heating to about 60 ° C. or more. Focusing on the progress of the reaction to form a cured resin, 95 to 10% by weight of hydroxyl-containing chlorinated polyolefin with good adhesion to polyolefin resin, 5-90% by weight of alkyl etherified amino resin and acidity The acid-curable coating composition composed of a catalyst not only exhibits excellent physical properties such as adhesion, weather resistance, moisture resistance, appearance, and solvent resistance to a polyolefin resin, but is also handled at about 60 ° C or less. As long as the curing reaction did not proceed, it was found that there was no pot life, and the present invention was accomplished.

The hydroxyl group-containing chlorinated polyolefin used in the present invention is a polyolefin-based resin, for example, crystalline polypropylene, non-crystalline polypropylene, polybutene-
1, polypentene-1, poly-4-methylpentene-1,
Low-density or high-density polyethylene, ethylene-propylene copolymer or the like alone or as a mixture of two or more, dispersed or dissolved in a chlorinated solvent, in the presence of a radical generator or under irradiation of ultraviolet light at 50 to 120 ° C Chlorinated polyolefin obtained by inhaling chlorine gas at a temperature, in the presence of a further radical generator, a hydroxyl group-containing acrylic monomer or a hydroxyl group-containing acrylic monomer and a hydroxyl group-free acrylic monomer It is obtained by graft copolymerization with a mixture. At the same time, at least one selected from the group consisting of air, oxygen, and ozone is blown simultaneously during chlorine inhalation in the polyolefin chlorination step to oxidatively modify the chlorinated polyolefin, thereby graft-copolymerizing the chlorinated polyolefin with an acrylic monomer. Can be performed smoothly.

The graft copolymerization of the chlorinated polyolefin and the acrylic monomer is performed by solution polymerization. The solvent to be used is most preferably an aromatic solvent such as toluene and xylene, and partially mixed with an ester solvent, a ketone solvent, an alcohol solvent, a chlorine solvent, an aliphatic solvent and a cycloaliphatic solvent. It does not matter if used. As the polymerization initiator, an organic peroxide system such as benzoyl peroxide or an azobis system such as azobisisobutyronitrile can be used. The basic method of graft copolymerization is to appropriately dilute the chlorinated polyolefin with a solvent, add an initiator, then heat and react while gradually adding an acrylic monomer. The system monomers may be mixed in advance, heated after adding an initiator, and reacted.

The hydroxyl group-containing chlorinated polyolefin of the present invention is obtained by graft copolymerizing a polyolefin with at least one unsaturated carboxylic acid monomer selected from carboxylic acids and / or carboxylic anhydrides so that the acid value becomes 6 to 60. Graft copolymerization of the post-chlorinated chlorinated polyolefin with a hydroxyl group-containing acrylic monomer or a mixture of hydroxyl group-containing acrylic monomer and non-hydroxyl group-containing acrylic monomer in the presence of a radical generator. Can also be used.

The method of graft copolymerizing one or two or more compounds selected from the group consisting of unsaturated polycarboxylic acids or acid anhydrides thereof with polyolefin is described below. The basic process is to add one or more compounds selected from the group consisting of unsaturated polycarboxylic acids or acid anhydrides thereof in the continuous system in the presence of a radical generator. Examples of one or more compounds selected from the group consisting of unsaturated carboxylic acids and acid anhydrides thereof include maleic acid, maleic anhydride, citraconic acid, citraconic anhydride, fumaric acid, and mesaconic acid. , Itaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride and the like. Examples of the radical generator include di-tert-butyl peroxide, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxide benzoate,
There are peroxides such as methyl ethyl ketone peroxide and di-tert-butyl diperphthalate, and azonitriles such as azobisisobutyronitrile.

Examples of the acrylic monomer containing a hydroxyl group used in the present invention include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and the like. Examples of the acrylic monomer containing no group include acrylic acid,
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, 2-ethylhexyl acrylate, lauryl acrylate, glycidyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-methacrylic acid
Butyl, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, glycidyl methacrylate and the like.

Alkyl etherified amino resin used in the present invention, urea, melamine, after reacting an amino compound such as benzoguanamine with formaldehyde to form methylol,
It is obtained by etherification with a lower alcohol such as methanol or butanol.

For example, n-butyl etherified urea resin, isobutyl etherified urea resin, methyl etherified melamine resin,
These may be used alone or in combination with n-butyl etherified melamine resin, n-butyl etherified benzoguanamine resin or the like.
They can be used in combination.

The acidic catalyst used in the present invention promotes the reaction between the hydroxyl group-containing chlorinated polyolefin and the alkyl etherified amino resin, and any acidic catalyst such as hydrochloric acid, nitric acid, phosphoric acid and organic acids can be used.

For example, alcoholic solutions of hydrochloric acid, salts of strong acids such as ammonium chloride, phosphates such as monobutyl phosphate, organic sulfonic acids such as p-toluenesulfonic acid, and the like, alone or in combination of two or more thereof Can be used.

The resin component of the composition of the present invention is the above-mentioned hydroxyl group-containing chlorinated polyolefin and the alkyl etherified amino resin, and the ratio of the alkyl etherified amino resin is 5% by weight.
If it is less than 1, the crosslink density becomes low, so that sufficient coating film performance cannot be obtained. On the other hand, when the content exceeds 90% by weight, the drying property of the coating film and the adhesion to the polyolefin resin deteriorate. Therefore, the proportion of the alkyl etherified amino resin in the resin content is usually 5 to 90% by weight, preferably 10 to 80% by weight.

The hydroxyl group-containing chlorinated polyolefin of the present invention can obtain a composition having good properties even when grafted and used only with an acrylic monomer having a hydroxyl group in the chlorinated polyolefin, but contains a hydroxyl group. By graft-copolymerizing a mixture of an acrylic monomer and an acrylic monomer containing no hydroxyl group, the toughness, weather resistance, moisture resistance, and the like of the coating film can be improved. In addition, the hydroxyl group content of the hydroxyl group-containing chlorinated polyolefin is 0.5 to
5.0% by weight is preferred. When the hydroxyl group content is less than 0.5% by weight, the effect of crosslinking with the alkyl etherified amino resin is small, and the solvent resistance and moisture resistance of the coating film are reduced.
If the hydroxyl group content exceeds 5.0% by weight, the adhesion to the polyolefin resin will be poor.

The chlorine content of the hydroxyl group-containing chlorinated polyolefin used in the present invention can be used in the range of 5 to 50% by weight, preferably 10 to 45% by weight. If the chlorine content is too low, the solution state will be poor, and if the chlorine content is too high, the adhesion to the polyolefin resin will be poor.

The advantage that the hydroxyl group-containing chlorinated polyolefin used in the present invention is graft-copolymerized with one or two or more compounds selected from the group consisting of the unsaturated polycarboxylic acids or acid anhydrides described above, When the composition is used as a primer, the adhesion to the topcoat is improved.

Further, the amount of the acidic catalyst used for promoting the reaction between the hydroxyl group-containing chlorinated polyolefin and the alkyl etherified amine resin can be reduced. In this case, the acid value of the polyolefin graft-copolymerized with one or two or more compounds selected from the group consisting of unsaturated polycarboxylic acids or acid anhydrides thereof is at least 6 or more, preferably 10 to 60. . If the acid value is too low, the adhesion to the topcoat is not significantly improved, and the effect as an acidic catalyst is small. On the other hand, if the acid value is too high, the adhesion to the polyolefin resin will be poor, and the moisture resistance and water resistance of the coating film will be reduced.

The solvent used in the composition of the present invention is most preferably a mixed solvent mainly composed of an alcohol and an aromatic hydrocarbon solvent.

Alcohols include methanol, ethanol, isopropanol and butanol, and aromatic hydrocarbon solvents include toluene and xylene. In addition, saturated cyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane are also good solvents.

Further, an ester solvent, a ketone solvent or the like may be partially mixed and used.

(Operation)

A feature of the present invention is that an acid-curable coating composition comprising a hydroxyl group-containing chlorinated polyolefin, an alkyl etherified amino resin, and an acidic catalyst can be applied to a polyolefin resin which is inherently difficult to adhere to. (1) The work time is greatly restricted by the fact that the reaction proceeds from the point when the main agent and the curing agent are mixed, for example.
(2) The remaining composition must be discarded when painting and printing are completed. (3) It is necessary to completely clean the used equipment and lines. In other words, the problem of resource saving and energy saving can be solved.

The composition according to the present invention may be used as it is after being coated, but it can be used as a paint or ink by adding a pigment or other additives. In addition, the composition exhibits well-balanced coating film properties by itself. However, if necessary, a cyclized rubber, a petroleum resin, an acrylic resin, an alkyd resin, or the like may be further used.

The composition according to the present invention is applied to a polyolefin-based resin sheet, film, or molded product, air-dried at room temperature, and then baked at a temperature of 60 ° C. or higher, preferably 80 ° C. or higher, to cure one coat finish. A coating is obtained.
The resulting coating film has excellent physical properties such as adhesion, weather resistance, water resistance, moisture resistance, and solvent resistance, and is used not only for polyolefin resins, but also for other plastics and substrates such as wood, steel, concrete, etc. Also applicable to:

Further, the composition according to the present invention can also be used as an undercoat paint of a polyolefin resin. As the top coat used at this time, existing paints such as melamine resin-based paint, epoxy resin-based paint, acrylic resin-based paint, urethane resin-based paint, and alkyd resin-based paint are suitable, and a conventional undercoat was used. Compared to coatings, it has excellent gasoline resistance, water resistance, moisture resistance, chemical resistance, bending resistance, impact resistance, etc., and has strong adhesion to both base materials and top coatings.

[Effects of Examples and the Invention]

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Measurement and Calculation of Acid Value A sample of about 4 g is taken in a 500 ml alkali-resistant Erlenmeyer flask, and 100 ml of distilled xylene is added. Heat for 1 hour with a reflux condenser. The solution was cooled to 75 ° C. or below and standardized. Add 30 ml of 0.1N KOH ethanol solution by burette. Heat at reflux for 45 minutes. After cooling, the standardized 0.1N CH ₃ COOH xylene solution is added by a burette until the mixture becomes acidic with phenolphthalein. At this time, add CH ₃ COOH in excess of at least 1 ml. The solution is then reheated at reflux for 15 minutes.
Stop heating, add 5 ml of water, and titrate with a 0.1 N KOH ethanol solution until the end point shows a faint pink. In the same way,
Perform a blank test with the same heating time as for the same amount of reagent.

 The calculation of the acid value is as follows.

Production Example-1 3 kg of isotactic polypropylene having a melt flow index of 1.5 measured according to JIS-K6758 was uniformly dissolved in carbon tetrachloride 70 under pressure, and chlorine was irradiated while irradiating ultraviolet rays at a temperature of 100 to 110 ° C. When the chlorination degree reaches about 10%, chlorination is performed until the chlorine content becomes 27% by weight while performing the oxidation treatment by injecting a mixed gas with a chlorine / oxygen volume ratio of 45 / 5.5. Was. After completion of the reaction, the solvent carbon tetrachloride was distilled off with an evaporator, and replaced with toluene.
A weight% toluene solution was obtained. Next, the toluene solution 1000
g, into a three-necked flask equipped with a stirrer, a dropping funnel, and a condenser for refluxing the solvent and monomer,
It was kept at 70-80 ° C. After adding 2 g of benzoyl peroxide and performing nitrogen gas replacement with stirring for about 30 minutes, 30 g of 2-hydroxylethyl methacrylate was successively added from a dropping funnel in about 2 hours, and graft polymerization was performed for about 3 hours. A chlorinated polypropylene having a hydroxyl group (having a hydroxyl group content of 1.7% by weight) was obtained.

Production Example-2 500 g of isotactic polypropylene having a melt viscosity of about 2600 CPS at 180 ° C. was placed in a three-necked flask equipped with a stirrer, a dropping funnel, and a condenser for refluxing monomers, and kept constant at 180 ° C. It melted completely in the oil bath. After performing nitrogen replacement in the flask for about 10 minutes,
While stirring, 20 g of maleic anhydride was added over about 5 minutes, then 2 g of di-tert-butyl peroxide was dissolved in 10 ml of hebutane, and added over about 30 minutes from a dropping funnel. At this time, the inside of the system was maintained at 180 ° C., and the reaction was continued for about 1 hour. Then, unreacted maleic anhydride was removed over about 30 minutes while reducing the pressure in the flask with an aspirator. The acid value of this product was 26. Next, 500 g of this product was put into a glass-lined reaction vessel, 10 carbon tetrachloride was added, and the mixture was sufficiently dissolved at 110 ° C. under a pressure of ² kg / cm ^2. 25% by weight
Until chlorine gas was blown. After completion of the reaction, the solvent, carbon tetrachloride, was distilled off with an evaporator and replaced with toluene to obtain a 20% by weight toluene solution of chlorinated polypropylene modified with maleic anhydride.

Production Example-3 1000 g of maleic anhydride-modified chlorinated polypropylene (20% by weight toluene solution) obtained in Production Example-2 was placed in a three-necked flask equipped with the same equipment as in Production Example-1, and 2 g of benzoyl peroxide and 2-methacrylic acid 2- Using 40 g of hydroxyethyl, graft polymerization was carried out in the same manner as in Production Example 1 to obtain a hydroxyl group-containing chlorinated polypropylene modified with maleic anhydride (hydroxyl group content: 2.2% by weight).

Production Example-4 1000 g of maleic anhydride-modified chlorinated polypropylene (20% by weight in toluene) obtained in Production Example-2 was placed in a three-necked flask equipped with the same equipment as in Production Example-1, and 2 g of benzoyl peroxide and 2-methacrylic acid 2- 20 g of hydroxyethyl,
Using 20 g of methyl methacrylate, graft polymerization was carried out in the same manner as in Production Example 1 to obtain a chlorinated polypropylene having a hydroxyl group modified with maleic anhydride (having a hydroxyl group content of 1.1% by weight).

Example-1 100 parts by weight of the hydroxyl group-containing chlorinated polyolefin obtained in Production Example-1 and Super Beckamine L-127-60 (manufactured by Dainippon Ink and Chemicals, Inc., n-butyl etherified melamine resin, nonvolatile content 60%) ) 16 parts by weight and 20 parts by weight of a solution of P-toluenesulfonic acid / 36% hydrochloric acid / isopropanol = 10/10/80 (weight ratio) as an acid catalyst were mixed, put in a completely closed vessel, and placed in a 40 ° C. atmosphere. And observed the viscosity change over time. The results are shown in Table 1.

Example 2 100 parts by weight of a hydroxyl group-containing chlorine polypropylene modified with maleic anhydride obtained in Production Example 3 and melan 220
(Hitachi Chemical Industries, Ltd., n-butyl etherified melamine resin, nonvolatile content 70%) 22 parts by weight and 10 parts by weight of the acid catalyst of Example 1 were mixed and stored in the same manner as in Example 1, The viscosity change over time was observed. The results are shown in Table 1.

Example-3 100 parts by weight of a hydroxyl group-containing chlorinated polypropylene modified with maleic anhydride obtained in Production Example-4 and melan 11
(Hitachi Chemical Industries, Ltd., butyl etherified urea resin, nonvolatile content 60%) 17 parts by weight and the acid catalyst of Example-1
10 parts by weight were mixed, stored in the same manner as in Example 1, and the viscosity change over time was observed. The results are shown in Table 1.

Comparative Example-1 100 parts by weight of maleic anhydride-modified chlorinated polypropylene obtained in Production Example-2, 2 parts by weight of Epotote YH-300 (a trifunctional epoxy resin manufactured by Toto Kasei Co., Ltd.) as a curing agent and a tertiary amine catalyst DBU [San Apro Co., Ltd.
1.8-diazabicyclo (5,4,0) undecene-7] 0.2
Parts by weight were mixed, stored in the same manner as in Example 1, and the viscosity change with time was observed. The results are shown in Table 1.

Comparative Example-2 100 parts by weight of carboxyl group-containing chlorinated polypropylene modified with maleic anhydride obtained in Production Example-2 and 6 parts by weight of Sumidur N-3200 (Sumitomo Bayer Urethane Co., Ltd., polyisocyanate) as a curing agent. The mixture was mixed and stored in the same manner as in Example 1, and the change in viscosity over time was observed. The results are shown in Table 1.

The viscosity was measured using a B-type viscometer. Measurement temperature is 25 ° C. The unit in the table is centipoise (CP). As can be seen from Table 1, the acid-curable coating compositions of Examples 1, 2, and 3 increase the varnish even after storage at 40 ° C for one month. Although hardly any viscosity is observed, Comparative Example 1-2 using the curing agent of
The liquid-curable composition thickens with time, reaches gelation in a few days, and becomes difficult to work. This shows that the present invention is very advantageous in operation.

Example 4 100 parts by weight of the hydroxyl group-containing chlorinated polypropylene obtained in Production Example 1 and Super Beckamine L-127-60 were mixed with 16 parts by weight.
Parts by weight and 20 parts by weight of titanium dioxide were mixed and dispersed in a pigment with a sand mill for 1 hour. Then, 20 parts by weight of the acid catalyst of Example 1 was added, and a mixed solvent of toluene / isopropanol = 95/5 (weight ratio) was used. Dilute to an appropriate viscosity and make the film thickness 40 ~ 50μ
Was spray-coated on a polypropylene plate (2 × 50 × 80 mm). After drying at room temperature for about 20 minutes, it was forcibly dried at 100 ° C. for 30 minutes, and allowed to stand in a room for 24 hours. Table 2 shows the results.

Example-5 100 parts by weight of a chlorinated polypropylene having a hydroxyl group and modified with maleic anhydride obtained in Production Example-3 and melan 220
Was mixed with 25 parts by weight of titanium dioxide and 25 parts by weight of titanium dioxide, and pigment dispersion was carried out in the same manner as in Example-4.
A coated plate was prepared in the same manner as in Example 4 in addition to parts by weight, and the coating film was tested. Table 2 shows the results.

Example -6 100 parts by weight of a hydroxyl group-containing chlorinated polypropylene modified with maleic anhydride obtained in Production Example 4 and melan 11
Was mixed with 25 parts by weight of titanium dioxide, and the pigment was dispersed in the same manner as in Example-4.
A coated plate was prepared in the same manner as in Example 4 in addition to parts by weight, and the coating film was tested. Table 2 shows the results.

Comparative Example-3 100 parts by weight of chlorinated maleic anhydride polypropylene obtained in Production Example-2 and 12 parts by weight of titanium dioxide were mixed to prepare a pigment dispersion and coated plate in the same manner as in Example-4, and a coating film test was performed. Was done. Table 2 shows the results.

Test method Adhesion: Make 100 goban eyes that reach the substrate at 1 mm intervals on the painted surface, and apply cellophane adhesive tape on it.
It was peeled off in the 180 ° direction, and the number of remaining goban eyes was checked.

Gasoline resistance: Scratch (×
) And immersed in regular gasoline at 25 ° C. for 2 hours to examine the state of the coating film.

Flex resistance: The film was bent 180 ° using a 1 / 2φ inch mandrel, and the state of the coating film was examined.

Impact resistance: Using a DuPont impact tester, 1/2 inch inch and 500 g load, dropped from 50 cm in frontal case and 25 cm in lining case.

Water resistance: The film was immersed in warm water of 50 ° C. for 240 hours, and the state of the coating film was examined.

Moisture resistance: The film was left in an atmosphere at 50 ° C. and a relative temperature of 98% or more for 240 hours, and the state of the coating film was examined.

From the coating film test results in Table 2, the acid-curable coating compositions of Examples 4, 5, and 6 show improvement in coating film properties due to crosslinking, such as gasoline resistance, water resistance, and moisture resistance. In the case of Example-3, these properties are inferior because the coating composition is not a curable coating composition,
A very dominant difference appears.

Example -7 100 parts by weight of a hydroxyl group-containing chlorine polypropylene modified with maleic anhydride obtained in Production Example 4 and Super Beckamine L-105-60 (manufactured by Dainippon Ink and Chemicals, methyl etherified melamine resin, Nonvolatile content 60%) 17
Parts by weight and 10 parts by weight of the acid catalyst of Example 1 were mixed, diluted to an appropriate viscosity with the mixed solvent of Example 4, and spray-coated on a polypropylene plate so as to have a film thickness of 5 to 10 μm.
After drying at room temperature for about 20 minutes, spray-coat low-temperature baking type melamine paint (manufactured by Kansai Paint Co., Ltd.) to a film thickness of 30 to 40μ, dry at room temperature for about 20 minutes, and force-dry at 100 ° C for 30 minutes. After standing still in the room for further 24 hours, the coating film was tested. The resulting coating film is excellent in gasoline resistance, bending resistance, impact resistance, moisture resistance, water resistance, etc., and also has extremely good adhesion, and the primer according to the present invention for coating a polyolefin resin. It turns out that it can be used as.

Claims (5)

(57) [Claims] A chlorinated polyolefin is graft-copolymerized with a hydroxyl group-containing acrylic monomer or a mixture of a hydroxyl group-containing acrylic monomer and a hydroxyl group-free acrylic monomer in the presence of a radical generator. Acid-curable coating for polyolefin resin comprising 95 to 10% by weight of a hydroxyl group-containing chlorinated polyolefin having a hydroxyl group content of 0.5 to 5.0% by weight, 5-90% by weight of an alkyl etherified amino resin and an acidic catalyst Composition. 2. A chlorinated polyolefin is obtained by grafting one or more compounds selected from the group consisting of unsaturated polycarboxylic acids and acid anhydrides to polyolefins such that the acid value is 6 to 60. The acid-curable coating composition for a polyolefin resin according to claim 1, which is chlorinated after polymerization. 3. The acid-curable coating composition for a polyolefin resin according to claim 1, wherein the chlorine content of the hydroxyl-containing chlorinated polyolefin is from 5 to 50% by weight. 4. The method according to claim 1, wherein the alkyl etherified amino resin is one or two selected from an alkyl etherified urea resin, an alkyl etherified melanin resin, and an alkyl etherified benzoguanamine resin. The acid-curable coating composition for a polyolefin resin according to any one of claims 1 to 7. 5. A method comprising mixing 95 to 10% by weight of a hydroxyl group-containing chlorinated polyolefin having a hydroxy group content of 0.5 to 5.0% by weight, 5 to 90% by weight of an alkyl etherified amino resin and an acidic catalyst. A method for producing the acid-curable coating composition for a polyolefin-based resin according to claim 1.