US20050224361A1

US20050224361A1 - Plating for automotive part

Info

Publication number: US20050224361A1
Application number: US11/101,408
Authority: US
Inventors: Shigetsugu Nakamura; Yoshihiko Kawai; Ichiro Horide
Original assignee: Takata Corp
Current assignee: Takata Corp
Priority date: 2004-04-13
Filing date: 2005-04-08
Publication date: 2005-10-13

Abstract

A plated automotive part and method of plating are provided. One or more semi-bright finish layers of nickel are plated onto an automotive part. One or more bright finish layers of nickel are plated onto the outermost, semi-bright finish layer of nickel. One or more layers of a hard coat are plated onto the outermost, bright-finish layer of nickel. The hard coat has a pencil hardness of 4H or greater.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application No. 60/561,531, filed Apr. 13, 2004, incorporated by reference herein.

BACKGROUND

The present invention relates to plated automotive parts and to methods of plating automotive parts.
As shown in FIG. 1, some automotive parts 10 are conventionally formed of a base metal 12 (e.g., steel) to which one or more layers of nickel (i.e., “Ni”) 14 is/are applied. An outer layer 16 of chromium metal has conventionally been applied to the layers 14 of Ni to complete the plating of the base metal 12.
FIG. 2 a details a conventional method of plating parts of the type shown in FIG. 1 with chromium metal. Specifically, in step S1, a base metal 12 is subjected to a pre-degreasing process. In step S2, the base metal 12 is degreased. In step S3, the degreased base metal 12 is subjected to water washing (one or more times). In step S4, the washed base metal 12 is subjected to acid cleaning (i.e., pickling). In step S5, the base metal 12 is again subjected to water washing (one or more times). In step S6, a semi-bright finish layer 14A of Ni is plated onto the base metal 12. The once-plated base metal 12 is then allowed to cool (i.e., recover) in step S7. In step S8, a bright finish layer 14B of Ni is plated onto the semi-bright layer 14A of Ni. In step S9, the twice-plated base metal 12 is again allowed to recover. In step S10, chromium activation occurs. In step S11, an outer layer 16 of chromium metal is plated onto the bright finish layer 14B of Ni. In step S12, the plated base metal 12 is again allowed to recover. In step S13, the plated base metal 12 is subjected to water washing (one or more times). Finally, in step S14, the plated base metal 12 is subjected to hot water washing.
The chrome plating gives the automotive part an attractive appearance and protects the part from scratches and rust because chromium metal has a high surface hardness and excellent wear and corrosion resistance. Additionally, when chromium metal is used to plate an automotive part such as a seatbelt tongue, use of chromium metal ensures easy fastening and releasing of the buckle and reliable latching due to the high surface hardness and excellent wear and corrosion resistance.
However, the chromium plating process requires the use of hexavalent chromium. Hexavalent chromium is a specified toxic substance, and its use requires treatment of wastewater and exhaust air to remove hexavalent chromium. Thus, manufacturers using hexavalent chromium must invest in, operate, and maintain a detoxification system and must pay additional costs to meet local regulatory requirements.
FIG. 2 b details a conventional method of detoxifying wastewater and exhaust air generated during the process shown in FIG. 2. Specifically, in step S101 (which occurs during and/or after steps S1 to S5 in FIG. 2 a), wastewater is treated to remove or neutralize alkali and acid. In step S102 (which occurs during and/or after steps S6 to S9 in FIG. 2 a), wastewater is treated to remove or neutralize Ni. In step S103 (which occurs during step S11 of FIG. 2 a), exhaust air is treated to remove hexavalent chromium by capturing hexavalent chromium mist released into the atmosphere during chromium plating and depositing the captured hexavalent chromium in the wastewater. In step S104 (which occurs during and/or after steps S10 to S14 in FIG. 2 a), wastewater is treated by a reduction treatment of hexavalent chromium to trivalent chromium. Finally, is step S105 (which occurs after step S104), other chromium is treated.
Even when the detoxification treatment is strictly managed, the use of hexavalent chromium presents environmental and safety risks. Such risks include leakage of hexavalent chromium from the manufacturing process potentially resulting in air, soil, and/or water contamination and adherence of hexavalent chromium to products potentially creating adverse health effects in persons exposed to the hexavalent chromium.
Additionally, manufacturers desiring to use hexavalent chromium must satisfy local regulatory requirements and obtain approval and licensing to use hexavalent chromium. Obtaining approval and licensing can be a lengthy process and, in some cases, approval may be impossible to obtain. Even if approval is obtained, risks to the manufacturer include production stoppages due to releases of hexavalent chromium, compensation paid to parties injured by hexavalent chromium contamination, and the cost of environmental cleanup due to hexavalent chromium pollution.
Thus, although chrome has proven to be an effective plating material, its use raises environmental concerns. What is needed, therefore, is an automotive plating and method of plating which, like chrome, provides effective plating properties but which is more environmentally friendly than chrome.

SUMMARY

According to an embodiment of the invention, a plated automotive part and method of plating are provided. One or more semi-bright finish layers of nickel may be plated onto an automotive part. One or more bright finish layers of nickel may be plated onto the outermost, semi-bright finish layer of nickel. One or more layers of a hard coat may be plated onto the outermost, bright-finish layer of nickel. According to a preferred embodiment, the hard coat has a pencil hardness of 4H or greater.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.
FIG. 1 is a cross-sectional view of an automotive part covered with a conventional plating material;
FIG. 2 a is a block diagram of a conventional plating method;
FIG. 2 b is a block diagram of a conventional wastewater and exhaust air treatment method;
FIG. 3 a is a cross-sectional view of an automotive part covered with a plating material according to an embodiment of the present invention;
FIG. 3 b is a cross-sectional view of an automotive part covered with a plating material according to an embodiment of the present invention;
FIG. 4 a is a block diagram of a plating method according to an embodiment of the present invention;
FIG. 4 b is a block diagram of a wastewater treatment method according to an embodiment of the present invention; and
FIG. 5 is a perspective view of an embodiment of a plated automotive part according to the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described below with reference to FIGS. 3 a-5.
As shown in FIG. 3 a, an automotive part 110 includes a base metal 12 (e.g., steel) onto which one or more layers 14 of Ni are applied. Moreover, although only two under layers 14 of Ni are shown, the invention contemplates plated parts and methods of plating involving any number of layers 14 of Ni. Regardless of the number of layers 14 of Ni, the outermost layer 14 of Ni is coated with a final layer 18, which is a hard coat layer.
The hard coat layer 18 may be clear so that the automotive part 110 has a metallic appearance of Ni. The hard coat layer 18 may have a pencil hardness of about 4H or greater and a thickness D1 of about 1 μm or greater. For example, the thickness D1 may be about 5 μm or greater. The hard coat layer 18 may comprise, for example, a material such as epoxy, acrylic, polyester, urethane, or melamine alkyl. The hard coat material according to the present invention is a more environmentally friendly material than conventional chromium plating material.
According to an embodiment of the invention, the thickness D1 of the outer layer 18 is about 6 μm or greater, and the outer layer 18 has a pencil hardness of about 4H or greater. In addition, although only one outer layer 18 is contemplated in this embodiment, more than one layer may be appropriate for some applications and are, therefore, fully within the scope of the invention.
According to another embodiment, the outer layer 18 is an inorganic hard coat layer such as, for example, an Si—R linked siloxane of a silicone containing compound as described in Japanese Patent Application No. JP2004-501233, incorporated by reference herein. In this embodiment, the outer layer 18 may have a pencil hardness of about 7H or greater and a thickness D1 of about 1 μm or greater.
According to another embodiment of the invention, the outer layer 18 of an automotive part 210 includes a first layer 18A of the hard coat and a second layer 18B of the hard coat, as shown in FIG. 3 b. The first layer 18A may have a thickness D2 of about 5 μm or greater, and the second layer 18B may have a thickness D3 of about 6 μm or greater. Additionally, the first layer 18A may have a pencil hardness of about HB or greater, and the second layer 18B may have a pencil hardness of about 4H or greater.
According to an embodiment, after the hard coat layer 18 is applied, the layer 18 is cured using a curing process that may include application of one or more of the following: (a) ultraviolet light; (b) heat; (c) far infrared radiation; and/or (d) near infrared radiation to the automotive part.
FIG. 4 a details a method of plating automotive parts of the type shown in FIG. 3 according to an embodiment of the present invention. Specifically, in step S1, a base metal 12 is subjected to a pre-degreasing process. In step S2, the base metal 12 is degreased. In step S3, the degreased base metal 12 is subjected to water washing (one or more times). The base metal 12 is preferably water washed two times. In step S4, the washed base metal 12 is subjected to acid cleaning (i.e., pickling). In step S5, the base metal 12 is again subjected to water washing (one or more times). The base metal 12 is preferably subjected to water washing two times. In step S6, a semi-bright finish layer 14A of Ni is plated onto the base metal 12. The once-plated base metal 12 is then allowed to cool (i.e., recover) in step S7. In step S8, a bright finish layer 14B of Ni is plated onto the semi-bright layer 14A of Ni. In step S9, the twice-plated base metal 12 is again allowed to recover. In step S13, the plated base metal 12 is subjected to water washing (one or more times). The plated base metal 12 is preferably subjected to water washing two times. In step S14, the plated base metal 12 is subjected to hot water washing.
Each of the above-described steps is similar to corresponding steps of the conventional method shown in FIG. 2 a. However, the present invention eliminates steps S10, S11, and S12, which involve chromium activation, chromium plating, and recovery of the chromium plated base metal 12. According to this embodiment, after step S14, the surface of the twice-plated base metal 12 is adjusted in step S15. In step S16, the hard coat layer 18 is applied. Finally, in step S17, the hard coat layer 18 is cured.
It should be recognized, as indicated by dashed lines in FIG. 4 a, in some embodiments of the method, after step S7, the method may return to step S6. In these method embodiments, one or more additional layers 14A of semi-bright finish Ni may be added to the first layer 14A of semi-bright finish Ni originally applied in step S6 by successively repeating steps S6 and S7. Upon adding a satisfactory number of semi-bright finish layers 14A of Ni, these method embodiments continue at step S8.
Similarly, as indicated by dashed lines in FIG. 4 a, in some embodiments of the method, after step S9, the method may return to step S8. In these method embodiments, one or more additional layers 14B of bright finish Ni may be added to the first layer 14B of bright finish Ni originally applied in step S8 by successively repeating steps S8 and S9. Upon adding a satisfactory number of bright finish layers 14B of Ni, these method embodiments continue at step S13.
Finally, as indicated by dashed lines in FIG. 4 a, in some embodiments of the method, after step S17, the method may return to step S16. In these method embodiments, one or more additional layers 18 of the hard coat may be added to the first layer 18 of hard coat originally applied in step S16 by successively repeating steps S16 and S17. Upon adding a satisfactory number of hard coat layers 18, these method embodiments stop after step S17.
FIG. 4 b details a method of treating wastewater according to an embodiment of the present invention. Specifically, in step S101 (which preferably occurs during and/or after steps S1 to S5 in FIG. 4 a), wastewater is treated to remove or neutralize alkali and acid. In step S102 (which occurs during and/or after steps S6 to S9 in FIG. 4 a), wastewater is treated to remove or neutralize Ni.
Each of the above-described steps is similar to corresponding steps of the conventional method shown in FIG. 2 b. However, the present invention eliminates step S103 of the conventional method, which involves capturing hexavalent chromium mist released into the atmosphere during chromium plating; eliminates step S104 of the conventional method, which involves wastewater reduction treatment of hexavalent chromium to trivalent chromium; and eliminates step S104 of the conventional method, which involves treatment of other chromium.
In an automotive part plated according to the method embodiments described above, the hard coat layer 18 may have a lower hardness and poorer wear resistance than conventional chromium plating. Thus, according to an embodiment of the present invention, the plated part may be protected from wear by minimizing the friction against the surface of the plated part. To protect the plated part (e.g., a seatbelt tongue), components in frictional contact with the plated part (e.g., a base and a latch of a seatbelt buckle) may include a coating containing molybdenum disulfide or fluorocarbon resin powder or may be treated with manganese phosphate plating or zinc plating having lower hardness than that of the alloy plating.
FIG. 5 shows an automotive part 30 plated pursuant to the method described in FIG. 4 a. The automotive part 30 may be, for example, a seatbelt tongue. However, the present invention is not limited to such tongues. Rather, the invention applies to any automotive part including, but not limited to, a seat belt buckle, a D-ring, a ball (which is part of a vehicle sensor mounted in a seat belt retractor), and other related automotive parts. Other automotive parts may also be plated, for example, parts used in airbag devices, seat weight sensors, and belt tension sensors may be plated according to the present invention. Further by way of example, a child seat and a steering wheel may be plated.
Thus, according to embodiments of the present invention, the use of a specified toxic substance in the plating of automotive parts is eliminated so that environmental protection and human safety is improved, wastewater and exhaust air treatment is improved, and manufacturing cost is reduced.
Given the disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.

Claims

1-49. (canceled)

50. A plated automotive part comprising:

a base metal;

a Ni layer on the base metal; and

an outermost plating layer including a hard coat,

wherein the outermost plating layer has a pencil hardness of 4H or greater.

51. The part of claim 50, wherein the outermost plating layer comprises epoxy.

52. The part of claim 50, wherein the outermost plating layer comprises acrylic.

53. The part of claim 50, wherein the outermost plating layer comprises polyester.

54. The part of claim 50, wherein the outermost plating layer comprises urethane.

55. The part of claim 50, wherein the outermost plating layer comprises melamine alkyl.

56. The part of claim 50, wherein the outermost plating layer comprises an Si-R linked siloxane of a silicone containing compound.

57. The part of claim 50, wherein the Ni layer includes a semi-bright finish layer directly on the base metal.

58. The part of claim 57, wherein the Ni layer includes a bright finish layer overlying the semi-bright finish layer.

59. The part of claim 50, wherein the outermost plating layer is clear.

60. The part of claim 50, wherein the outermost plating layer comprises an inorganic hard coat.

61. The part of claim 60, wherein the outermost plating layer has a thickness of about 1 μm or greater and a pencil hardness of about 7H or greater.

62. The part of claim 50, wherein a thickness of the outermost plating layer is about 6 μm or greater.

63. The part of claim 50, wherein the outermost plating layer includes a first outermost plating layer and a second outermost plating layer, and wherein the first outermost plating layer has a thickness of about 5 μm or greater and the second outermost platinf layer has a thickness of about 6 μm or greater.

64. The part of claim 63, wherein the first outermost plating layer has a pencil hardness of about HB or greater and the second outermost plating layer has a pencil hardness of about 4H or greater.

65. The part of claim 50, wherein the plated automotive part is configured to engage a corresponding automotive part, and wherein a surface of the corresponding automotive part configured to contact the plated automotive part has a hardness lower than the harness of the outermost plating layer of the plated automotive part.

66. The part of claim 65, wherein the surface of the corresponding automotive part includes a coating containing molybdenum disulfide.

67. The part of claim 65, wherein the surface of the corresponding automotive part includes a coating containing fluorocarbon resin powder.

68. The part of claim 65, wherein the surface of the corresponding automotive part includes a manganese phosphate plating.

69. The part of claim 65, wherein the surface of the corresponding automotive part includes a zinc plating.

70. A seat belt tongue comprising an outermost plating layer including a hard coat having a pencil hardness of 4H or greater.

71. The tongue of claim 70, wherein the outermost plating layer comprises epoxy.

72. The tongue of claim 70, wherein the outermost plating layer comprises acrylic.

73. The tongue of claim 70, wherein the outermost plating layer comprises polyester.

74. The tongue of claim 70, wherein the outermost plating layer comprises urethane.

75. The tongue of claim 70, wherein the outermost plating layer comprises melamine alkyl.

76. The tongue of claim 70, wherein the outermost plating layer comprises an Si—R linked siloxane of a silicone containing compound.

77. The tongue of claim 70, wherein a thickness of the outermost plating layer is about 5 μm.

78. The tongue of claim 70, wherein the outermost plating layer overlies at least one Ni layer.

79. The tongue of claim 70, wherein the outermost plating layer is clear.

80. The tongue of claim 70, wherein the outermost plating layer comprises an inorganic hard coat.

81. The tongue of claim 80, wherein the outermost plating layer has a thickness of about 1 μm or greater and a pencil hardness of about 7H or greater.

82. The tongue of claim 70, wherein a thickness of the outermost plating layer is about 6 μm or greater.

83. The tongue of claim 70, wherein the outermost plating layer includes a first outermost plating layer and a second outermost plating layer, and wherein the first outermost plating layer has a thickness of about 5 μm or greater and the second outermost plating layer has a thickness of about 6 μm or greater.

84. The tongue of claim 83, wherein the first outermost plating layer has a pencil hardness of about HB or greater.

85. The tongue of claim 83, wherein the second outermost plating layer has a pencil hardness of about 4H or greater.

86. The tongue of claim 70, wherein the tongue is configured to engage a seat belt buckle having a base and a latch, and wherein a hardness of a surface of the base and a hardness of a surface of the latch are lower than the harness of the outermost plating.

87. The tongue of claim 86, wherein the surfaces of the base and the latch include a coating containing molybdenum disulfide.

88. The tongue of claim 86, wherein the surfaces of the base and the latch include a coating containing fluorocarbon resin powder.

89. The tongue of claim 86, wherein the surfaces of the base and the latch include a manganese phosphate plating.

90. The tongue of claim 86, wherein the surfaces of the base and the latch include a zinc plating.