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US-12618159-B2 - Chemical conversion coating agent, surface-treated metal and surface treatment method

US12618159B2US 12618159 B2US12618159 B2US 12618159B2US-12618159-B2

Abstract

A chemical conversion coating agent that enables chemical conversion coating by which favorable corrosion resistance is obtained after coating. A chemical conversion coating agent which contains (A) at least one metal component that is selected from the group consisting of zirconium, titanium and hafnium, (B) fluorine and (C) an allylamine-diallylamine copolymer, wherein the content of the metal component (A) is 10 to 10,000 ppm by mass in terms of elemental metal relative to the total mass of the chemical conversion coating agent; the content ratio of a diallylamine segment derived from diallylamine in the allylamine-diallylamine copolymer (C) is 52% to 98% by mole relative to the total of an allylamine segment derived from allylamine and the diallylamine segment; the weight average molecular weight of the allylamine-diallylamine copolymer (C) is 500 to 500,000; and the content of the allylamine-diallylamine copolymer (C) is 25 to 5,000 ppm by mass in terms of the resin solid content concentration relative to the total mass of the chemical conversion coating agent.

Inventors

  • Takayuki Ueno
  • Yu KOGANEZAWA

Assignees

  • NIPPON PAINT SURF CHEMICALS CO., LTD.

Dates

Publication Date
20260505
Application Date
20220324
Priority Date
20210331

Claims (16)

  1. 1 . A chemical conversion coating agent comprising (A) at least one metal component selected from a group consisting of zirconium, titanium, and hafnium, (B) fluorine and (C) an allylamine-diallylamine copolymer, wherein: a content of the metal component (A) is 10 to 10,000 ppm by mass in terms of elemental metal relative to a total mass of the chemical conversion coating agent; a content ratio of a diallylamine segment derived from the diallylamine in the allylamine-diallylamine copolymer (C) is 52% to 98% by mole relative to a total of an allylamine segment derived from the allylamine and the diallylamine segment; the allylamine-diallylamine copolymer (C) has a weight average molecular weight of 500 to 500,000; and a content of the allylamine-diallylamine copolymer (C) is 25 to 5,000 ppm by mass in terms of resin solid content concentration relative to the total mass of the chemical conversion coating agent.
  2. 2 . The chemical conversion coating agent according to claim 1 , further comprising at least one metal component selected from a group consisting of aluminum and zinc.
  3. 3 . The chemical conversion coating agent according to claim 2 , wherein the chemical conversion coating agent has a pH of 2.0 to 6.0.
  4. 4 . The chemical conversion coating agent according to claim 2 , wherein the allylamine-diallylamine copolymer (C) is an acid addition salt having anionic counter ions, and an acid constituting the acid addition salt has a dissociation constant (pKa) in a range of −3.7 to 4.8.
  5. 5 . The chemical conversion coating agent according to claim 2 , wherein a concentration of the fluorine (B) is 10 to 12,500 ppm by mass in terms of elemental fluorine relative to the total mass of the chemical conversion coating agent.
  6. 6 . The chemical conversion coating agent according to claim 1 , wherein the chemical conversion coating agent has a pH of 2.0 to 6.0.
  7. 7 . The chemical conversion coating agent according to claim 6 , wherein the allylamine-diallylamine copolymer (C) is an acid addition salt having anionic counter ions, and an acid constituting the acid addition salt has a dissociation constant (pKa) in a range of −3.7 to 4.8.
  8. 8 . The chemical conversion coating agent according to claim 6 , wherein a concentration of the fluorine (B) is 10 to 12,500 ppm by mass in terms of elemental fluorine relative to the total mass of the chemical conversion coating agent.
  9. 9 . The chemical conversion coating agent according to claim 1 , wherein the allylamine-diallylamine copolymer (C) is an acid addition salt having anionic counter ions, and an acid constituting the acid addition salt has a dissociation constant (pKa) in a range of −3.7 to 4.8.
  10. 10 . The chemical conversion coating agent according to claim 9 , wherein a concentration of the fluorine (B) is 10 to 12,500 ppm by mass in terms of elemental fluorine relative to the total mass of the chemical conversion coating agent.
  11. 11 . The chemical conversion coating agent according to claim 1 , wherein a concentration of the fluorine (B) is 10 to 12,500 ppm by mass in terms of elemental fluorine relative to the total mass of the chemical conversion coating agent.
  12. 12 . The chemical conversion coating agent according to claim 1 , further comprising a silane coupling agent.
  13. 13 . A surface-treated metal, having a surface on which a chemical conversion film is formed by the chemical conversion coating agent according to claim 1 .
  14. 14 . The surface-treated metal according to claim 13 , wherein a content of the metal component (A) in the chemical conversion film is 5 to 500 mg/m 2 in terms of elemental metal.
  15. 15 . A surface treatment method comprising forming a chemical conversion film by treating a surface of a coat object with the chemical conversion coating agent according to claim 1 .
  16. 16 . The surface treatment method according to claim 15 , further comprising forming an electrodeposited coating film by subjecting the coat object having the chemical conversion film to electrodeposition coating.

Description

TECHNICAL FIELD The present invention relates to a chemical conversion coating agent, a surface-treated metal, and a surface treatment method. BACKGROUND ART Conventionally, chemical conversion coating has been previously applied to a metal substrate surface for the purpose of improving corrosion resistance, coating film adhesiveness, and the like when applying cationic electrodeposition coating or powder coating to metal substrate surfaces. In recent years, chemical conversion coatings using a chromium-free zinc phosphate have been widely performed. The chemical conversion coating using zinc phosphate is difficult from the viewpoint of waste water treatment due to a high reactivity of the treatment agent and has had a problem of a great environmental burden in addition to generation of sludges. Thus, chemical conversion coating agents composed of at least one selected from a group consisting of zirconium, titanium, and hafnium, as well as fluorine and a water-soluble resin have been proposed (e.g. see Patent Document 1). Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2004-218074 DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The technology disclosed in Patent Document 1 makes it possible to apply a good chemical conversion coating to metals such as iron, zinc, and aluminum. However, corrosion resistance obtained after cationic electrodeposition coating, powder coating, or the like has still had room for improvement. The present invention was made in view of the above circumstances, and an object of the present invention is to provide a chemical conversion coating agent that enables a chemical conversion coating with favorable corrosion resistance after coating. Means for Solving the Problems (1) The present invention relates to a chemical conversion coating agent including (A) at least one metal component selected from a group consisting of zirconium, titanium, and hafnium, (B) fluorine and (C) an allylamine-diallylamine copolymer, in which the content of the metal component (A) is 10 to 10,000 ppm by mass in terms of elemental metal relative to the total mass of the chemical conversion coating agent; the content ratio of a diallylamine segment derived from the diallylamine in the allylamine-diallylamine copolymer (C) is 52% to 98% by mole relative to the total of an allylamine segment derived from the allylamine and the diallylamine segment; the allylamine-diallylamine copolymer (C) has a weight average molecular weight of 500 to 500,000; and the content of the allylamine-diallylamine copolymer (C) is 25 to 5,000 ppm by mass in terms of resin solid content concentration relative to the total mass of the chemical conversion coating agent.(2) The chemical conversion coating agent according to (1), further including at least one metal component selected from a group consisting of aluminum and zinc.(3) The chemical conversion coating agent according to (1) or (2), in which the chemical conversion coating agent has a pH of 2.0 to 6.0.(4) The chemical conversion coating agent according to any one of (1) to (3), in which the allylamine-diallylamine copolymer (C) is an acid addition salt having anionic counter ions, and an acid constituting the acid addition salt has a dissociation constant (pKa) in a range of −3.7 to 4.8.(5) The chemical conversion coating agent according to any one of (1) to (4), in which a concentration of the fluorine (B) is 10 to 12,500 ppm by mass in terms of elemental fluorine relative to the total mass of the chemical conversion coating agent.(6) The chemical conversion coating agent according to any one of (1) to (5), further including a silane coupling agent.(7) A surface-treated metal, having a surface on which a chemical conversion film is formed by the chemical conversion coating agent according to any one of (1) to (6).(8) The surface-treated metal according to (7), in which a content of the metal component (A) in the chemical conversion film is 5 to 500 mg/m2 in terms of elemental metal.(9) A surface treatment method including forming a chemical conversion film by treating a surface of a coat object with the chemical conversion coating agent according to any one of (1) to (6).(10) The surface treatment method according to (9), further including forming an electrodeposited coating film by subjecting the coat object having the chemical conversion film to electrodeposition coating. Effects of the Invention According to the present invention, it is possible to provide a chemical conversion coating agent that enables chemical conversion coating with favorable corrosion resistance after coating. PREFERRED MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be explained below. The present invention is not limited to the description of the following embodiment. <Chemical Conversion Coating Agent> By the chemical conversion coating agent according to the present embodiment, a chemical conversion film with favorabl