SPRING WITH HIGH DURABILITY AND METHOD OF COATING THE SAME

Abstract

A spring with high durability has a coating film composed of an epoxy resin powder coating containing softening agent which contains an epoxy resin and a softening agent comprising a thermoplastic resin for improving impact resistance of the coating film. A method of coating a spring with high durability comprises a coating step of making an epoxy resin powder coating containing softening agent which contains an epoxy resin and a softening agent comprising a thermoplastic resin for improving impact resistance of a coating film adhere to a surface on which the coating film is formed, and a baking step of baking the epoxy resin powder coating containing softening agent adhered to the surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of its advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings and detailed specification, all of which forms a part of the disclosure.

FIG. 1 is a pattern diagram for illustrating a constitution of coating of a powder coating which is produced by a melting kneading method.

FIG. 2 is a pattern diagram for illustrating a constitution of coating of a powder coating which is produced by a dry blend method.

Claims

1. A spring coated with a coating film comprising an epoxy resin powder coating, wherein the epoxy resin powder coating comprises an epoxy resin and a softening agent comprising a thermoplastic resin.

2. A spring as claimed in claim 1, wherein said epoxy resin powder coating is produced by a dry blend method.

3. A spring as claimed in claim 1, wherein the said softening agent is present in an amount of from 5 wt % to 15 wt % based on the total weight of said epoxy resin powder coating.

4. A spring as claimed in claim 1, wherein said thermoplastic resin is at least one selected from the group consisting of a urethane resin, an acrylic resin, a polyamide resin and a polyolefin resin.

5. A spring as claimed in claim 1, wherein the roughness of the uppermost surface is Rzjis5 μm or more in axial direction and Rzjis10 μm or more in circumferential direction.

6. A spring having a two-layered coating film comprising an undercoat layer and a topcoat layer present on said undercoat layer, wherein at least one of said two layers comprises an epoxy resin powder coating comprising an epoxy resin and a softening agent comprising a thermoplastic resin.

7. A spring as claimed in claim 6, wherein said undercoat layer comprises said epoxy resin powder coating, and said epoxy resin powder coating further comprises zinc.

8. A spring as claimed in claim 7, wherein the content of said zinc in the epoxy resin powder coating is from 75 wt % to 100 wt % based on the total weight of said epoxy resin powder coating.

9. A spring as claimed in claim 6, wherein said topcoat layer has a thickness of from 200 μm to 600 μm.

10. A spring as claimed in claim 6, further comprising a phosphate film is present under said undercoat layer.

11. A method of coating a spring which comprises: coating the spring with an epoxy resin powder coating comprising an epoxy resin and a softening agent comprising a thermoplastic resin; and thenbaking said spring coated with the epoxy resin powder coating.

12. A method of coating a spring which comprises: undercoating the spring with a undercoating powder coating to form an undercoated spring having an undercoat film;topcoating the undercoated spring with a topcoating powder coating to form a topcoated spring having a topcoat film;baking said undercoated and topcoated spring to adhere the topcoat film and undercoat film on said spring;wherein at least one of said undercoating powder coating and said topcoating powder coating is an epoxy resin powder coating comprising an epoxy resin and a softening agent comprising a thermoplastic resin.

13. A method of coating a spring as claimed in claim 12, further comprising: preheating said spring to from 70° C. to 120° C. before said undercoating.

14. A method of coating a spring as claimed in claim 13, wherein said topcoating is carried out at a temperature of from 60° C. to 80° C. with the residual heat of said preheating.

15. A method of coating a spring as claimed in claim 12, further comprising forming a phosphate film on an uncoated surface of said spring, before said undercoating.

16. A method of coating a spring as claimed in claim 12, further comprising baking said undercoating powder coating between said undercoating and said topcoating.