WO2001025355A1

WO2001025355A1 - Coating film structure with high weatherability

Info

Publication number: WO2001025355A1
Application number: PCT/JP1999/005462
Authority: WO
Inventors: Daisuke Tanizawa; Ryuji Iwakiri; Ryoichi Fukagawa; Keisuke Tano; Nobuhiko Tsuda
Original assignee: Daikin Industries, Ltd.
Priority date: 1999-10-04
Filing date: 1999-10-04
Publication date: 2001-04-12
Also published as: AU6002799A

Abstract

A coating film structure with high weatherability which comprises a substrate, a colored coating layer formed thereon directly or through a primer layer, and a clear coating layer formed directly on the colored coating layer from a thermosetting fluororesin powder coating composition. Thus, the colored undercoat film can be sufficiently protected and the whole coating film has improved weatherability. Hence, the structure is suitable for use especially in the exterior coating of vehicles, etc.

Description

Akira Itoda High weather resistant coating structure technology

The present invention relates to a highly weather-resistant coating structure formed using a powder coating. Such a coating structure is suitable as a top coat for vehicles. Background technology

Thermosetting powder coatings are environmentally friendly because they do not use organic solvents, and they also have excellent coating performance because they do not use organic solvents. It is widely used in the field. As such thermosetting powder coatings, there are known acrylic resin-based, epoxy resin-based, polyester resin-based, and polyester-based powder coatings. ing . When forming a coating film having excellent transparency as the outermost layer (top coat) of the coating film, an acrylic resin-based coating material is used. It is. Paints based on acrylic resin are relatively inexpensive, have high coating film hardness, and have excellent stain resistance. However, there is a problem that the weather resistance is insufficient, and the protection of the undercoating color coating film is not sufficient.

On the other hand, fluorine resin-based thermosetting powder coatings are known as coatings having excellent weather resistance (Japanese Patent Publication No. 6-107492, Japanese Patent Publication No. Japanese Patent Publication No. Hei 11-103, 702, Special Publication 6-3 4 5 8 2 2 Publication, Special Publication 6-184, 243, etc.) Resin-based powder coatings are expensive, have inadequate compatibility with other resins, and have poor adhesion to substrates. Yes, it is easy to apply acrylic resin powder coating. It could not be used as a powder paint instead of a paint.

The present invention successfully draws out the advantages of general-purpose resin powder coatings and the advantages of fluororesin, and has improved weather resistance at a relatively low price. The aim is also to provide a coating structure that makes use of the design properties of the coloring pigment. Disclosure of the invention

That is, the present invention relates to a colored coating layer formed on a base material with or without a primer layer interposed therebetween, and the colored coating layer. The present invention relates to a high weather-resistant coating structure comprising a clear coating layer formed from a thermosetting fluororesin powder coating provided directly above the coating.

As the color coating film layer, acrylic resin, polyethylene resin, epoxy resin, thermosetting type polyester resin, thermosetting type fluororesin Or a coating formed from a solvent-based coating, an aqueous dispersion-type coating, an electrodeposition coating or a powder coating containing at least two of these ¾t □ resins. It is preferably a film layer, and the thermosetting fluororesin powder forming the clear coating film has a bridging reactive group as the clear coating material. Powder clear coatings made of fluorine resin, which is a thermosetting type fluorine-containing copolymer, are preferred.

The clear coating layer preferably contains an ultraviolet absorber and Z or an oxidation inhibitor.

The coating structure of the present invention is obtained by applying a thermosetting type coloring paint on a substrate with or without a single layer of a primer, and then thermosetting. Molded fluororesin powder After coating with clear paint, both can be baked at the same time to harden and form.

The coating structure of the present invention is suitable as a coating structure for a vehicle exterior. Best form to carry out the invention

The coating structure of the present invention is obtained by coating a base material with or without a single layer of a primer, a coloring paint, that is, a paint containing a coloring pigment. Then, a fluororesin powder clear paint is applied as a top coat, and then baked and hardened at the same time.

Coloring paints are resin paints, water-dispersible paints, electrodeposition paints, or powder paints, in which the resin component and the color paint are essential components. As the resin component, either thermoplastic or thermosetting resin can be used.

Among these, the water-based dispersion type coating has the advantage that it does not use an organic solvent and does not deteriorate the environment, and that it can form a smooth and clear coating film. I like it.

Examples of resin components for coloring paints include a hydroxyl group, a carboxyl group, an epoxy group, an amide group, an amino group, and a methyl group. Bridging reactive groups such as lecapto groups, glycidyl groups, bromine atoms, iodine atoms, etc., active halogen atoms, isocanato groups, etc. Acrylic resin obtained by copolymerizing an acrylic acid or methyl acrylate acid ester having a copolymer with another copolymerizable monomer. Polyester resin obtained by the condensation reaction of polyvalent carboxylic acid and polyalcohol; epoxy resin; Non-fluoroplastic and thermoplastic or thermosetting trees such as urethane resin obtained by reacting , Is to La thermal Allowed 塑 was your good beauty / or the Ru is heat hardening type off Tsu element Kitsuki purport force Oh up, et al.

Acrylic resin is described in, for example, the official gazette of Japanese Utility Model Laid-open Publication No. 6-233396, the official gazette of Japanese Patent Laid-open Publication No. Hei 1-2344473, etc. Anything that you know can be used.

As the epoxy resin, for example, those described in the official gazette of Japanese Examined Patent Application Publication No. Sho 61-515169 can be used.

As the urethane resin, for example, those described in, for example, Japanese Patent Publication No. 6-2333965 can be used.

As the polyester resin, there can be used, for example, those described in, for example, the official gazette of Japanese Patent Application Publication No. Sho 61-551 169.

For fluororesin, for example, Japanese Patent Publication No. 6-1104792, Japanese Patent Publication No. 1-15995, and Japanese Patent Publication No. 6-1884 In addition to those listed in the public bulletin of No. 24 3, known thermoplastic thermoplastic resins can be used.

These resins can be used alone or as a mixture of two or more kinds thereof as a powder coating resin component for a color coating film.

As the hardening agent, a conventionally known hardening agent can be used in accordance with the resin component. As a specific example, for example, a block isocyanate compound obtained by blocking a dissociated compound with a blocking agent is used. can give . Examples of the isocyanate compounds include, but are not limited to, isophorone socinet, trirange isocyanate, and kirisireto. For example, the techno-equipment, the 4,4'-diphenyl methacrylate techno-solate, the hexamethylene thiocyanate, etc. Polyisocyanate compounds and their multimeric alcohols, such as dimers or trimers, trimethylolpropane, etc. Modified polyisocyanate compounds and the like can be exemplified. Examples of blocking agents include ε-force pro- gram, Knoll, benzyl alcohol, methyl ketoxim, etc. are available. As the strong block isocyanate compound, a compound that is solid at room temperature is preferable. In addition, aliphatic dibasic acids such as fumaric acid, conodic acid, adipic acid, azelanic acid, sebacic acid and dodecane diacid; Acids such as waterless fluoric acid, waterless trimellitic acid, waterless pyromellitic acid; waterless; glass with an acid value of 10 to 300 mg KOH / g Polyester resin or acryl having a transition temperature of 30 to 120 ° C and a number average molecular weight of 100 to 150 Resin; dithiazamide or dithiazamide derivative; imidazole or imidazole derivative; dibasic acid dihydrazide , Diaminophenyl methane, cyclic amide compounds, and other amide compounds: melamine resin; diglycidyl terephthalate Estel, Pa Roxy benzoic acid diglycidyl ester, triglycidyl isocitrate, spiroglycol glycol diglycidyl ether Glycidyl compounds such as ter, hydanthoin compounds, and alicyclic epoxy resins; 1,4—bis 2 ′ —hydroxy compounds Shibenzen, bishydroxyl terephthalate evening rate, styrene-real-real callal copolymer, spiroglycol , Tris 2 — hydroxyethyl isocyanurate, hydroxyl value 10 to 300 mg Glass transfer temperature at 30 mg KOH / g 30 to 1 And a hydroxyl group content of a polyester resin or an acrylic resin having a number average molecular weight of 1,000 to 1,500,000. Compounds, etc.

The weight ratio of the resin component to the hardener is in the range of 40/60 to 98 da2, preferably in the range of 50Z50 to 97Z3.

Further, a hardening catalyst may be used in addition to the hardening agent. Hardening catalysts include, for example, tetrabutylammonium mouth lid, tetrabutylammonium bromide, and tetrabutylammonium bromide. Class 4 ammonia such as rabbit ammonium Salts: 4th-grade phosphine, such as ethyl triphenylphosphine salt, etc. Salts: 4th-grade phosphine, salt phos, etc. Imidazoles such as 2-methylimidazol; dibutyltin dilaurate, stannous octanate, etc. Organic tin compounds; methyl trisulfuron imide, tin methansulfonate, and the like. The curing catalyst may be added in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the resin component.

Coloring paints to be mixed with paints for coloring coatings can be paints that are conventionally used.

The coloring pigment may be either an organic pigment or an organic pigment. When inorganic pigments are used, it is possible to greatly improve the retention rate of the coating film during exposure. In addition, the use of baked pigments, such as metal oxides and composite metal oxides, among the inorganic pigments reduces the change in color difference. be able to . In addition, when an organic pigment is used, it is possible to improve the color development during melting and kneading.

The inorganic pigments include metal oxides, compound metal oxides, metal salts, metals, rusters, ultralamins, and gold-red pinks. The powder is crushed. Furthermore, titanium oxide, iron oxide, chromium oxide, and the like are metal oxides, and titanium, nickel, and nickel are metal oxides. , Cobalt, niob, zinc, iron, chromium, aluminum, manganese, norium, zirconium, etc. Complex metal oxides, etc., in which the metal forms the crystal structure, are metal salts, such as iron, chromium, molybdenum, iron, etc. Examples of such metals are aluminum and stainless steel. Organic pigments include condensed azo compounds, isoindolinone compounds, quinacridone compounds, dike pilloropolole compounds, and ancestors. Laquinon System, dioxazine system, metal complex azo system, arylamide system, azo system, garylide system, pyrrazozone system, trina system Powders such as phthalocyanine, base dye lakes, naphthol, and benzimidazo-based powders.

The amount of the pigment to be incorporated is 100 to 200 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of the resin component.

In addition, various additives usually included in coloring paints, for example, fillers, ultraviolet absorbers, leveling agents, flow regulators, acids An antioxidant, a heat degradation inhibitor, an glazing modifier, a charge control agent, and the like may be appropriately combined.

The application of the coloring paints may be carried out in a usual manner and under conditions suitable for the form of each paint. However, in the present invention, as will be described later, after applying a fluorine resin powder clear paint for a top coat, it is baked at the same time. Because of the hardening, the color coating does not burn at the painting stage.

The base material to be coated is not limited to metal base materials such as iron, aluminum, copper, and their alloys, but may be glass, cement, or the like. Inorganic base materials such as components and concrete; FRP, acrylic resin, vinyl chloride resin, polycarbonate resin, polyurea resin, etc. A variety of base materials, such as synthetic resin base materials; natural base materials such as wood and fiber.

In addition, the primer may be painted in advance on the metal base material. In addition, if the metal base is subjected to preparatory treatments such as washing, degreasing, degreasing, surface conditioning, and chemical treatment, adhesion and protection can be reduced. More preferred. Examples of degreasing treatments include strong cleaning such as soaking with soda, soda, and caustic soda, and spraying with a spray. The removal process involves the use of blast materials, such as aluminum, silicon carbide, iron powder, and glass. The method of spraying the base material at a high speed has been improved. Examples of surface conditioning treatments include immersion of the surface conditioning agent in an aqueous solution and spraying. The chemical conversion treatments include zinc phosphate, iron phosphate, clostri, chromic acid, immersion in chromic linoleic acid, and spraying. -Processing is performed in a favorable manner.

When used for vehicle coating, metal substrates such as iron, aluminum, or these alloys are usually used as base materials.

Then, as a top coat, heat-curable fluorine resin powder clear paint is applied to form a clear layer. A cured hardened fluorine resin powder for the clear layer is used as a clear coating for thermosetting hardened fluorine-containing copolymers having a bridging reactive group and a hardener. More preferably, it comprises an oxidation inhibitor and a Z or UV absorber. Of course, various additives such as repelling agents, flow regulators, heat degradation inhibitors, gloss regulators, charge control agents, etc. may be appropriately combined. You can do it. In particular, when an ultraviolet absorber and an oxidation inhibitor are combined, the protection of the undercoating color coating film is greatly improved.

As the thermosetting type fluorine-containing copolymer which is a resin component, for example, Japanese Patent Publication No. 6-1104792, Japanese Patent Publication No. 6-4778 No. 5 Public Bulletin, Tokuhoku Hei 1 11 0 3 6 7 0 Public Bulletin, Tokkai Hira 6-3 4 5 8 2 2 It is possible to use the powers described in the official bulletin of Japanese Patent Publication No. 9-1 6 5 5 3 5 etc.

Specifically, a fluoropolymer containing a fluorinated refin unit as an indispensable component and having a bridging reactive group is exposed.

Tri-fluoro-ethylene, tetra-fluoro ethylene, tri-fluoro ethylene, tri-fluorene , Vinylidene fluoride, hexafluoropropylene, ぺ Fluoropropylene, etc. can be exemplified, and it is suitable according to the properties required for the coating film, the copolymer component or the combination with the hardener. You may choose it. In addition, one or more of these fluororefins can be used. The crosslinkable reactive groups of the thermosetting fluorine-containing copolymer used in the present invention include a hydroxyl group, a carboxyl group, an epoxy group, and an amino group. Active groups such as de-, amino-, mercapto- and glycidyl groups, bromine, iodine, etc., genogen, isocyanate, etc. The basics are enhanced.

Examples of thermosetting fluorine-containing copolymers include, for example, chlorotrifluoroethylene (CTFE) Z cyclohexyl vinyl Ether (c-HXVE) Z Hydroxybutyvinyl (HBVE) copolymer, tetrafluoroethylene (TFE) Z iso Butylene ZHBVE copolymer, TFEZ Hexafluoropropylene (HFP) Ethylene ZHBVE copolymer, vinylidene fluoride (VdF) No TFE / perfluorobutenoic acid copolymer, CTFE / c-HXVE noarylglycidyl ether copolymer, CTFEZ c—HxVEZ Leic acid copolymer, TFE Neusobutylene Z-aryl Glycidyl ether copolymer, TFE 7 HFPZ Ethylene Z-aryl Daricyl ether copolymer, TFEZ isobutylene Z waterless maleic acid copolymer, TFEZHFPZ ethylene Z waterless maleic acid copolymer, Examples include the VdFZTFEZHBVE copolymer, the VdF-no-TFEZ maleic anhydride copolymer, and the VdFZTFE / aryl-glycidyl ether copolymer. It is.

In addition, the thermosetting type fluorine-containing copolymer used for the thermosetting powder clear coating has a fluorine content of 10% by weight or more. I want to do that. When the fluorine content is less than 10% by weight, a coating film having sufficient weather resistance cannot be obtained.

The curing agent and curing catalyst to be used may be selected from those described above. The amount of the mixture is the same.

Further, it is desirable that the thermosetting type fluorine-containing copolymer has a glass transition temperature of 30 to 120 ° C. When the glass transition temperature is 30 ° C or lower, the storage stability of the obtained coating composition is not sufficient, and when the temperature exceeds 120 ° C, the melt-kneading property is increased. descend .

In addition to the thermosetting fluorine-containing copolymer as a powder resin component, a non-fluorinated thermosetting resin for powders, for example, having a bridging reactive group Acrylic resin, epoxy resin, urea resin, polyester resin, etc. may be mixed. The amount of the copolymer is at most 100 parts by weight, preferably at most 80 parts by weight, based on 100 parts by weight of the fluorine-containing copolymer. Too much will reduce the weather resistance.

Powder clear coatings for clear coatings include heat-curable fluorine-containing copolymers, hardeners, ultraviolet absorbers, and oxidation inhibitors. After being blended, it can be manufactured by the usual method of melting, kneading, and pulverizing. The obtained thermosetting powder coating composition preferably has a glass transition temperature of from 30 to 120 t, particularly from 35 to 100. When the glass transition temperature is less than 30 ° C, the glass transition temperature does not easily become a solid and cannot be used as a thermosetting powder coating composition. On the other hand, when the glass transition temperature exceeds 120, the softening point becomes too high, and the flow of the coating film becomes difficult. The average particle size of the powder coating is usually not more than 400 / xm.

Coating is done, for example, using a commercially available electrostatic powder coating machine or fluid immersion Coating method depending on the installation can be adopted. After this coating, it is combined with the colored coating in a hot-air oven, infrared oven, induction heating oven, etc.

The film is baked at ~ 200 ° C to form a coating film (so-called "one-coat-on-one-bake method").

The thickness of the clear coating film may be selected according to the price, weather resistance, transparency, etc., but it is usually 1 to 200 m, and is preferably

It is 10 to 70 m.

Next, the present invention will be described specifically with reference to manufacturing examples and working examples, but the present invention is limited to such working examples only. No.

Production example 1 (production of colored paint)

Acrylic resin varnish (numerical average molecular weight: 1200, hydroxyl group) prepared according to Production Example 1 of Japanese Patent Publication No. 70, acid value 58, non-volatile content 50% by weight) 1 1 2 copies of aluminum facial preparation prepared in Production Example 8 of the official gazette (Toyo Aluminum Co., Ltd. 's aluminum paste 716 ON, hardening agent (methylated methylol melamin) and isostate. 15 3 0 with Allied acid phosphate

Z 2 weight ratio mixture) 47 Addition of 7 parts by weight, and production according to Production Example 4 of the official gazette, containing a lyophilic group. Coloring paint was manufactured by adding 43 parts by weight of acid (acid value: 16.2, non-volatile part: 33% by weight), and then dispersing and mixing into a sufficient amount. Production example 2 (Manufacture of clear paint)

A stainless steel steel pressure-resistant reactor with a capacity of 300 m1 and a stirrer, t-butanol (157 g), cyclohexylbi 2 g of ether (c-HXVE) 16 g, isobutyryl vinyl (i-BVE) 9 g, 4—hydroxypuccinyl vinyl ether (HBVE) 25 g, potassium carbonate lg Add 0.07 g of azobisisobutylonitrile (AIBN) and remove dissolved air by solid deaeration using liquid nitrogen. Was Then, tri-fluoroethylene (CTFE) 5 Og was introduced, and the temperature was gradually increased. The reaction was continued under agitation while maintaining the temperature at 60.After 10 hours, the reactor was cooled with water, cooled to room temperature, and then unreacted. The reaction was terminated and the reaction was terminated by releasing the reactor. Then, the mixture was heated to 60X: and the dispersing medium was removed under reduced pressure of 1 mmHg for 24 hours to obtain a fluorine-containing copolymer. The obtained fluorine-containing copolymer was analyzed by ' ⁹ F-NMR,-NMR and elemental analysis methods, and CTFE / c-H x VEZi-BVEZHBVE (5 0/15/15/25 mol%), with a hydroxyl value of 120 mg KOH / g, a glass transition temperature of 45, and heating. The weight loss was 2% or less, and the solid viscosity [η] measured at 30 in tetrahydrofuran was 0.21. This fluorine-containing copolymer was pulverized with an impact-type mill-mill.

This fluorine-containing copolymer powder 61.5 parts by weight hardener (ε one-sided product block isocyanate, manufactured by Huls, Inc.) -15.3 0) 36.3 parts by weight, antioxidant (IRGANOX B 900, manufactured by Cibagayi Co., Ltd.) 0.24 parts by weight and ultraviolet absorber ( 1.996 weight parts are melted and kneaded in a melt extruder (Bus Conider from Buss), extruded and cooled. After that, it is finely pulverized with a hammer set impact mill and passed through a 150-mesh wire mesh to produce thermosetting fluororesin powder clear paint. did .

Manufacturing example 3 (Manufacture of clear paint)

In Production Example 2, the absence of the oxidation inhibitor was In the same manner, powder clear paint was produced.

Production example 4 (Manufacture of clear paint)

A powder clear coating was produced in the same manner as in Production Example 2 except that the oxidation inhibitor and the ultraviolet absorber were not combined. .

Manufacturing example 5

Japanese Patent Publication No. 6-2 3 3 9 6 5 Acrylic resin manufactured according to Production Example 16 of Publication No. Methyl methacrylate copolymer, glass transfer temperature 50 ° C, number average molecular weight 250 0) 70 weight parts, 1,10-deca 23.4 parts by weight of benzoic acid, 1.0 parts by weight of benzoin and a polysiloxane-based leveling agent (Toshiba Silicon Co., Ltd.) 0.3 parts by weight were melted and kneaded in a melt extruder (Bus Kneader of Bus Company), extruded and cooled. Then, finely pulverized with a hammer-type impact pulverizer, and passed through a 150 mesh wire mesh to produce a thermosetting acrylic resin powder clear paint. Was

Example 1

The colored paint obtained in Production Example 1 was applied to an object to be described later in an air spray method in an atmosphere of a temperature of 23: and a humidity of 85% RH by an air spray method. The coating was performed so that the dry film thickness became 20 m (1 minute per bar), and then heating was performed at 80 for 2 minutes. Then, the powder clear paint obtained in Production Example 2 was spray-coated with 乾燥 et-on- ー et so that the dry film thickness was 60 m. It was painted in one step according to the law. After setting for 7 minutes, it was baked in a dryer at 180 ° C for 20 minutes to harden it, and a coated plate for testing was produced. An outdoor exposure test was performed on this coated board. The results are shown in Table 1. (Coating object)

A degreased polished mild steel sheet coated with electrodeposition paint for automobiles and baked was used.

(Outdoor exposure test)

Exposure was carried out outdoors at Miyakojima, Okinawa, at a temperature of 30 degrees on the south side for two years, and the characteristics of nails were examined.

Hikarizawa Retention: Gloss before and after exposure is measured with a Hikarizawa meter (manufactured by Suga Test Instruments Co., Ltd.), and the retention of Hizawa after exposure is calculated.

Visual appearance: The painted plate after exposure is visually observed.

Color difference (ΔE): The color difference before and after exposure is measured with a color difference meter DP-300 manufactured by Minol Yu.

Examples 2 to 3 and Comparative Example 1

Except for using the paint shown in Table 1 as the powder clear paint, a test coated plate was prepared in the same manner as in Example 1 and the same as in Example 1. An outdoor exposure test was conducted. The results are shown in Table 1.

Film structure Outdoor exposure test

Gloss retention

Colored paint Clear paint Visual appearance Color difference (Δ E)

(%)

Example 1 Production Example 1 Production Example 2 9 6 No abnormality 1.6 Example 2 Production Example 1 Production Example 3 9 5 No abnormality 2.5 Example 3 Production Example 1 Production Example 4 9 2 No abnormality 5.3 Comparative Example 1 Production example 1 Production example 5 3 0 Microcracks 1 0.2 Industrial applicability

According to the coating structure of the present invention, the protection of the undercoat colored coating film can be sufficiently achieved, and the weather resistance of the entire coating film is further improved. It is suitable for painting the exterior of vehicles.

Claims

Scope of the request The color coating layer provided on the base material with or without the primer layer interposed and directly above the color coating layer A highly weather-resistant coating structure consisting of a clear coating layer formed from the heat-hardened fluorine resin powder paint.

The structure according to claim 1, wherein the coloring coating layer is a coating layer formed of a water-dispersible paint.

The structure according to claim 1 or 2, wherein said clear coating film layer contains an ultraviolet absorber and Z or an oxidation inhibitor.

The structure described in any one of paragraphs 1 to 3 of the claim, which is a coating structure of the exterior of a vehicle.

A thermosetting coloring paint is applied to the substrate with or without a primer layer in between, and then a thermosetting fluororesin powder powder clear coating A method for producing a highly weather-resistant coating film, characterized in that after coating, both are baked and cured at the same time.