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EP0643996A1 - Procédé de revêtement - Google Patents

Procédé de revêtement Download PDF

Info

Publication number
EP0643996A1
EP0643996A1 EP94114613A EP94114613A EP0643996A1 EP 0643996 A1 EP0643996 A1 EP 0643996A1 EP 94114613 A EP94114613 A EP 94114613A EP 94114613 A EP94114613 A EP 94114613A EP 0643996 A1 EP0643996 A1 EP 0643996A1
Authority
EP
European Patent Office
Prior art keywords
coating
powder coating
coated
plastic
coat
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP94114613A
Other languages
German (de)
English (en)
Other versions
EP0643996B1 (fr
Inventor
Koichi Tsutsui
Shannon Libke
Koichi Inoue
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Paint Co Ltd
Original Assignee
Nippon Paint Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Paint Co Ltd filed Critical Nippon Paint Co Ltd
Publication of EP0643996A1 publication Critical patent/EP0643996A1/fr
Application granted granted Critical
Publication of EP0643996B1 publication Critical patent/EP0643996B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
    • B05D1/045—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field on non-conductive substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
    • B05D1/06—Applying particulate materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/02—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to macromolecular substances, e.g. rubber

Definitions

  • the present invention relates to an coating process wherein a powder coating is applied by an electrostatic coating method on the surface of the substrates formed with plastic or coated coat.
  • Japanese Kokoku Publication Sho-51-43152 discloses a technique for top coating with a powder coating after formation of a base coat with a thermosetting resin coating, which comprises heating the substrate to reduce the content of the volatile component of the base coat to not more than 6 weight % to thereby improve the metallic tone and durability of the coat as well as transfer efficiency.
  • Japanese Kokai Publication Hei-2-194878 discloses a technique for coating plastic substrates wherein the prevention of popping is sought by heating the substrate to a temperature necessary for degassing prior to application of the coating.
  • the object of the present invention is to provide an electrostatic coating method employing a powder coating which provides for good transfer efficiency with consequent reduction of powder recovery load and, hence, is useful for conservation of resources and management of wastes.
  • the gist of the present invention is that in a coating process applying a powder coating on the surface of the substrates formed with plastic or coated coat by electrostatic coating method, the temperature of said substrates is brought to a level not below the glass transition temperature of the component resin of said powder coating or the glass transition temperature of the component resin of of said plastic or coated coat prior to application of said powder coating.
  • the coating process according to the present invention can be applied to the surface of plastic. Moreover, the coating process according to the present invention can be applied to the surface of metal or plastic after formation of a coated coat as a base coat with electrodeposition coating, aqueous coating, solvent type coating or powder coating. Said metal may for example be an iron or other electrically conductive material, and particularly preferred are iron phosphate-treated steel and zinc phosphate-treated steel sheets.
  • said surface of plastic and said surface of metal or plastic after formation of a coated coat which are the substrates for application of the coating process according to the present invention, are collectively referred to as 'the surface of the substrates formed with plastic or coated coat'.
  • powder coating there is no particular limitation on the powder coating that can be used in the practice of the present invention.
  • coatings using a polyester resins, acrylic resins, epoxy resins or other resins as the vehicle can be mentioned as examples.
  • the pigment and additives are incorporated in such a vehicle to provide a powder with a nonvolatile content of 100 %.
  • the particle size of the powder coating in terms of bulk mean particle diameter, is 5 to 50 ⁇ m and preferably 8 to 40 ⁇ m.
  • the proportion of particles up to 5 ⁇ m in diameter is preferably not more than 25 weight %.
  • the standard deviation of the particle size distribution is preferably not greater than 20 ⁇ m.
  • the standard deviation of a particle size distribution is expressed by [ ⁇ ⁇ (D - X) 2 F ⁇ / ⁇ F ] 1/2 , where D is the diameter of each individual particle, X is the bulk mean particle diameter and X is ⁇ (D F)/ ⁇ F , and F is the frequency of particles.
  • plastic is not critical, either.
  • the plastic may be thermoplastic or thermosetting and need not necessarily be reinforced.
  • phenolic resins inclusive of phenol-cellulose versions, silicone resins, amino resins, polyurethanes, polystyrenes, polypropylene, thermoplastic acrylic resins, polyvinyl chloride, polyacrylonitrile, polybutadiene and acrylonitrile-butadiene copolymers can be mentioned as examples.
  • boron fiber and other fibers except glass fiber can be employed.
  • the temperature of the substrate is brought to a level not below the glass transition temperature of the resin component of the powder coating or not below the glass transition temperature of the resin constituting the plastic or coated coat.
  • the substrate can be preheated prior to application of the powder coating.
  • the powder coating can be applied before cooling of the substrate after baking.
  • the above-mentioned temperature of the substrate is preferably not higher than the upper limit of baking temperature for the powder coating, and when the surface of the substrate formed with coated coat is used, the upper limit of said temperature is preferably not higher than the upper limit of baking temperature for said coated coat and for the powder coating.
  • the upper limit of said temperature is preferably lower than the deformation temperature of said plastic.
  • the above-mentioned temperature is within the range of 40 to 140°C.
  • the transfer efficiency is poor, while the use of any temperature over 140 °C may cause partial curing of the powder coating to detract from the appearance of the coated product.
  • the volatile content of the base coat is controlled to not more than 10 weight %. If this limit of 10 weight % is exceeded, foaming, surface roughness, and yellowing may occur to detract from the appearance of the final product. The preferred limit is 5 weight % or less.
  • the content of the volatile amine compound is to be controlled to not more than 2.0 weight %. If this limit of 2.0 weight% is exceeded, the appearance of the finished product will not be as good as desired.
  • the preferred limit is 1.5 weight % and the still preferred limit is 1.2 weight %.
  • the surface of the substrates formed with plastic or coated coat is first brought to the above-mentioned temperature and then applied electrostatic coating method with the powder coating.
  • the electrostatic coating method as such can be carried out in the conventional manner.
  • an electrically conductive particulate substance such as graphite powder
  • the plastic substrate can be coated with an electrically conductive primer or an electrically conductive wash solution to impart electric conductivity.
  • An iron phosphate-treated steel sheet was electrocoated (Powertop, U Series, Nippon Paint Co., Ltd.) in a coating thickness of 20 ⁇ m and further intermediate-coated (OTOH Series, Nippon Paint Co., Ltd.) in a coating thickness of 35 ⁇ m.
  • the intermediate-coated steel sheet was then coated with the aqueous metallic coating prepared in Reference Example 1 and baked at 80°C for 10 min., at 100°C for 10 min. and at 120 °C for 10 min.
  • This coated sheet was brought to the respective temperatures shown in Table 1 and, then, coated electrostatically using the acrylic powder coating prepared in Reference Example 2 (coating conditions: applied voltage -80 kV, delivery rate 120 g/min.).
  • the transfer efficiency was then evaluated for each sample. The results were shown in Table 1. [Table 1] Temperature 25°C 60°C 100°C 120 °C Transfer efficiency 51% 63% 78% 81%
  • a plastic blank for automotive bumper use (Tg : 90°C, Mitsui Petrochemical Co., Ltd.) was treated with trichloroethane and coated with a conductive primer(RB-1140 CD primer, Nippon B Chemical Co., Ltd.).
  • This plastic blank was brought to the respective temperatures shown in Table 2 and coated electrostatically using the acrylic powder coating prepared in Reference Example 2 under the same coating conditions as in Example 1. The transfer efficiency was then evaluated. The results were shown in Table 2. [Table 2] Temperature 25°C 60°C 100°C Transfer efficiency 48% 60% 82%
  • Example 1 an iron phosphate-treated steel sheet was electrocoated, then intermediate-coated and further coated with the aqueous metallic coating prepared in Reference Example 1.
  • the coated sheet was preheated at 80°C for 5 min. and 10 min., at 90°C for 5 min., at 100°C for 5 min., at 130 °C for 5 min. and at 140°C for 5 min. Then, without cooling, the sheet was coated with the acrylic powder coating prepared in Reference Example 2 under the same conditions as in Example 1 and baked at 150 °C for 25 min.
  • the content of the nonvolatile component (weight %) and volatile amine compound (weight % based on total nonvolatile matter) of the aqueous metallic coat after preheating were determined and the appearance was rated.
  • Example 1 A zinc phosphate-treated steel sheet, 0.6 mm in thickness, was coated with the same intermediate coating as used in Example 1 in a coating thickness of 35 ⁇ m. This coated sheet was brought to the respective temperatures indicated in Table 4 and coated electrostatically with the polyester powder coating prepared in Reference Example 3 under the same conditions as in Example 1. The transfer efficiency was then evaluated. The results are shown in Table 4. [Table 4] Temperature 20°C 70°C 120°C Transfer efficiency 58% 70% 81%
  • the invention is of value for the prevention of pollution and management of wastes. Furthermore, in the production sequence of (steel sheet)-(primer)-(bake)-(cool)-(powder coat), the (cool) step can be omitted. In the coating process for automotive bodies, the (cool) step in the sequence of (aqueous base coat)-(preheat)-(cool)-(powder top clear coat) can be similarly omitted. Therefore, the present invention is of value for the conservation of labor and energy.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
EP19940114613 1993-09-17 1994-09-16 Procédé de revêtement Expired - Lifetime EP0643996B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP25501493 1993-09-17
JP255014/93 1993-09-17

Publications (2)

Publication Number Publication Date
EP0643996A1 true EP0643996A1 (fr) 1995-03-22
EP0643996B1 EP0643996B1 (fr) 1998-03-11

Family

ID=17273002

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19940114613 Expired - Lifetime EP0643996B1 (fr) 1993-09-17 1994-09-16 Procédé de revêtement

Country Status (2)

Country Link
EP (1) EP0643996B1 (fr)
DE (1) DE69408925T2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996032529A1 (fr) * 1995-04-12 1996-10-17 Alliedsignal Inc. Substrat polymerique avec produits d'addition et procede de fabrication par diffusion causee par un phenomene thermique
WO2003020505A1 (fr) * 2001-08-28 2003-03-13 Toray Industries, Inc. Materiau en plaque de cfrp et procede de preparation correspondant

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110577660B (zh) * 2019-08-14 2020-07-31 佛山宜可居新材料有限公司 一种有机高分子材料及其涂装方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1265945A (fr) * 1960-05-25 1961-07-07 Rhone Poulenc Sa Nouveau procédé de revêtement à l'aide de poudres de matières plastiques
DE3324726A1 (de) * 1983-07-08 1985-01-17 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Verfahren zum herstellen eines mehrschichtigen ueberzuges auf einem durch pulverlackieren im elektrostatischen feld zu beschichtenden traeger
EP0372740A2 (fr) * 1988-12-02 1990-06-13 Ppg Industries, Inc. Procédé pour revêtir des substrats plastiques au moyen de compositions de revêtement en poudre

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1265945A (fr) * 1960-05-25 1961-07-07 Rhone Poulenc Sa Nouveau procédé de revêtement à l'aide de poudres de matières plastiques
DE3324726A1 (de) * 1983-07-08 1985-01-17 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Verfahren zum herstellen eines mehrschichtigen ueberzuges auf einem durch pulverlackieren im elektrostatischen feld zu beschichtenden traeger
EP0372740A2 (fr) * 1988-12-02 1990-06-13 Ppg Industries, Inc. Procédé pour revêtir des substrats plastiques au moyen de compositions de revêtement en poudre

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996032529A1 (fr) * 1995-04-12 1996-10-17 Alliedsignal Inc. Substrat polymerique avec produits d'addition et procede de fabrication par diffusion causee par un phenomene thermique
WO2003020505A1 (fr) * 2001-08-28 2003-03-13 Toray Industries, Inc. Materiau en plaque de cfrp et procede de preparation correspondant
US7059665B2 (en) 2001-08-28 2006-06-13 Toray Industries, Inc. CFRP plate material and method for preparation thereof
KR100704808B1 (ko) * 2001-08-28 2007-04-10 도레이 가부시끼가이샤 Ｃｆｒｐ제 판재 및 그의 제조 방법

Also Published As

Publication number Publication date
DE69408925D1 (de) 1998-04-16
DE69408925T2 (de) 1998-09-24
EP0643996B1 (fr) 1998-03-11

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