METHOD FOR THE SURFACE TREATMENT AND/OR MANUFACTURE OF A MEDICAL PRODUCT, AND MEDICAL PRODUCT

Abstract

A medical product and a method of surface treatment and/or manufacture of a medical product. The medical product includes a metal or an alloy or consists of a metal or an alloy. The method includes the following steps: a) dulling a surface of the medical product, b) electropolishing the dulled surface of the medical product, c) electrochemically etching the dulled and electropolished surface of the medical product and d) electropolishing the dulled, electropolished and electrochemically etched surface of the medical product. The medical product has at least one of the following features: a pitting corrosion potential of 100 mV to 1200 mV, and/or a contact angle of 80° to 140°, and/or a passive layer having a thickness of 1 nm to 10 nm, which coats at least sections of the surface of the medical product.

Claims

1. A method of surface treatment and/or manufacture of a medical product, the medical product comprising a metal or an alloy, wherein the method comprises the steps of: a) dulling a surface of the medical product, b) electropolishing the dulled surface of the medical product, c) electrochemically etching the surface of the medical product; and d) electropolishing the surface of the medical product,  wherein step b) and step d) are each conducted at a voltage of 2.0 V to 10.0 V and/or step b) and step d) are each conducted at a current density of 5 A/dm.sup.2 to 50 A/dm.sup.2, and  wherein step c) is conducted at a voltage of 1.2 V to ≤2.1 V and/or at a current density of 1.4 A/dm.sup.2 to 2.4 A/dm.sup.2.

2. The method according to claim 1, wherein step a) is preceded by a grinding operation on the surface of the medical product.

3. The method according to claim 2, wherein step a) is performed by treating the surface of the medical product with a blasting agent.

4. The method according to claim 1, wherein step b) is conducted over a period of 30 s to 130 s.

5. The method according to claim 1, wherein step b) and step d) are each conducted at a voltage of 5 V to 9 V and/or each at a current density of 8 A/dm.sup.2 to 40 A/dm.sup.2.

6. The method according to claim 1, wherein step c) is conducted over a period of 30 s to 130 s.

7. The method according to claim 1, wherein step c) is conducted at a voltage applied to an anode of 1.4 V to 1.7 V and/or at a current density of 1.6 A/dm.sup.2 to 2.2 A/dm.sup.2.

8. The method according to claim 1, wherein step d) is conducted over a shorter period than step b).

9. The method according to claim 1, wherein steps b), c) and d) are each conducted using an acidic aqueous electrolyte solution comprising a mineral acid.

10. The method according to claim 1, further comprising the step of: e) treating the surface of the medical product with a passivating acid or a passivating acid-containing solution after steps a), b), c) and d).

11. The method according to claim 10, wherein step e) comprises treating the surface of the medical product with the passivating acid, and wherein the passivating acid is citric acid and/or nitric acid.

12. The method according to claim 10, further comprising the steps of: f) sterilizing the medical product; and g) packing the medical product, wherein step f) is performed prior to step g), or step f) is performed after step g).

13. The method according to claim 1, wherein the medical product consists of a stainless steel.

14. A medical product producible by the method according to claim 1, the medical product comprising a passive layer having a thickness of 1 nm to 10 nm that coats at least parts of the surface of the medical product.

15. The medical product according to claim 14, wherein the medical product is a medical instrument.

16. The method according to claim 1, wherein step a) is preceded by a slide finishing and/or belt finishing on the surface of the medical product.

17. The method according to claim 1, wherein step a) is performed by treating the surface of the medical product with a ductile blasting agent and/or blasting agent that are/is free of corners and/or edges.

18. The method according to claim 1, wherein step a) is performed by treating the surface of the medical product with a blasting agent comprising a metal or an alloy.

19. The method according to claim 9, wherein the mineral acid is selected from the group consisting of phosphoric acid, sulfuric acid and a mixture thereof.

20. The method according to claim 1, wherein the medical product consists of a chromium-containing corrosion-resistant stainless steel.

Description

DETAILED DESCRIPTION

[0190] Further features and advantages of the invention will be apparent from the description of preferred embodiments with reference to examples that follow. It is possible here for features of the invention each to be implemented on their own or in combination with one another. The embodiments described hereinafter serve to further elucidate the invention without restricting it thereto.

EXAMPLES

1. Surface Treatment of a Surgical Instrument or Representative Specimens Thereof by a Method of the Invention

[0191] The specimens used were produced from the same material (X20Cr13) and with the same manufacturing steps as the surgical instruments (e.g. clamps, needle holders, shears with hard metal and the like).

[0192] SEM/EDX analyses (extraneous material and doubled-over material) were conducted on the instruments.

[0193] Potentiodynamic tests (pitting corrosion potential) were likewise conducted on the instruments.

[0194] Contact angle measurements (contact angle) were conducted on sample platelets (planar surface without shadows).

[0195] Scratch resistance measurements (volume of the wear scar) were conducted by means of a pin-on-disk experiment on sample platelets.

[0196] Prior to the surface treatment, surgical instruments and sample platelets according to the current production chain of surgical instruments were shaped and heat-treated.

[0197] For subsequent surface treatment, a surgical instrument (Aesculap BH110R clamp) and sample platelets were first treated by means of slide finishing in acidic solution over a period of four hours and then brightened by slide finishing in aqueous solution over a period of one hour.

[0198] Thereafter, the surgical instrument and the sample platelets were treated by means of blasting. Blasting agents used were stainless steel wire grains having an average ball diameter of 300 μm. An injector blasting system was used for the blasting. The blasting was conducted under a pressure of 2 bar.

[0199] Subsequently, the surface of the surgical instrument and of the sample platelets was electrochemically processed in an electrolyte composed of phosphoric acid (38% by weight to 58% by weight) and sulfuric acid (26.6% by weight to 52.0% by weight) at 80° C. For this purpose, a current density of 18.5 A/dm.sup.2 was first employed. The electropolishing was conducted over a period of 90 seconds. A voltage of 5 to 6 volts was established here. Thereafter, operation was continued at a current density of 1.9 A/dm.sup.2. The electrochemical etching was conducted over a period of 90 seconds. A voltage of 1.8 to 2.1 volts was established here. Finally, a current density of 18.5 A/dm.sup.2 was once again employed. The electropolishing was conducted over a period of 10 seconds. A voltage of 5 to 6 volts was established here.

[0200] Thereafter, the surface of the surgical instrument and of the specimens was passivated. For this purpose, the surgical instrument and the sample platelets were immersed into a 14.4% by weight nitric acid. The passivating was conducted at a temperature of 40° C. over a period of 10 minutes.

[0201] Finally, the instrument and the sample platelets were dried under an air atmosphere at 80° C. for 10 minutes.

[0202] On conclusion of the surface treatment of the surgical instrument and of the test specimens, no doubled-over material or overlapping material and no extraneous material transfer were detectable. The instruments had a pitting corrosion potential of 565 mV. The sample platelets had a contact angle of 106.8°. The volume of the wear scar was not measurable since wear was too low.

2. Surface Treatment of a Surgical Instrument By a Method of the Generic Type

[0203] A surgical instrument (Aesculap BH110R clamp) and sample platelets were first treated by means of slide finishing over a period of four hours. Thereafter, the surgical instrument and the sample platelets were brightened over a period of one hour.

[0204] Thereafter, the surgical instrument and the specimens were treated by means of blasting. For this purpose, glass beads having an average diameter of 40 μm to 70 μm were used. The blasting was conducted in an injector blasting system under a pressure of 4 bar.

[0205] Subsequently, the surgical instrument and the specimens were subjected to passivation. For this purpose, a 10% by weight citric acid solution was used. The passivating was effected at a temperature of 55° C. over a period of 10 minutes.

[0206] On conclusion of the surface treatment of the surgical instrument and of the sample platelets, many instances of doubled-over material or overlapping material were detectable. In addition, an extraneous material transfer of 1.2% was detected. The pitting corrosion potential of the corrosion specimens was 356 mV. In addition, the sample platelets had a contact angle of 66.0°. The volume removed in the wear scar was 55 244 μm.sup.3.

CONCLUSION

[0207] The above-described comparison of a method of the invention and of a method of the generic type shows that the method of the invention leads to more corrosion-resistant and especially more scratch-resistant products. On top of that, the method of the invention is capable of reducing the risk of occurrence of surface discoloration by comparison with methods of the generic type. Moreover, the method of the invention leads to products of better cleanability (see contact angles measured).