PECVD lubricity vessel coating, coating process and apparatus providing different power levels in two phases
View Patent ↗A method for coating a substrate surface such as a syringe part by PECVD is provided, the method comprising generating a plasma from a gaseous reactant comprising an organosilicon precursor and optionally an oxidizing gas by providing plasma-forming energy adjacent to the substrate, thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD). The plasma-forming energy is applied in a first phase as a first pulse at a first energy level followed by further treatment in a second phase at a second energy level lower than the first energy level. The lubricity, hydrophobicity and/or barrier properties of the coating are set by setting the ratio of the O 2 to the organosilicon precursor in the gaseous reactant, and/or by setting the electric power used for generating the plasma.
1. A method for preparing a lubricity coating on a plastic substrate, the method comprising:
(a) providing a gas comprising an organosilicon precursor, optionally an oxidizing gas, and an inert gas in the vicinity of the substrate surface;
(b) generating plasma in the gas by applying plasma-forming energy adjacent to the plastic substrate as a first pulse at a first energy level; and
(c) after said step (b), generating plasma in the gas by applying plasma-forming energy adjacent to the plastic substrate as a second pulse at a second energy level lower than the first energy level;
thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD).
2. The method of claim 1 , in which the first pulse energy level is from 21 to 100 Watts.
3. The method of claim 1 , in which the first pulse is applied for 0.1 to 5 seconds.
4. The method of claim 1 , in which the second pulse energy level is from 1 to 10 Watts.
5. The method of claim 1 , in which the container size is from 1 to 10 mL.
6. The method of claim 1 , in which the lubricity coated container is further treated by post heating it at 50 to 110 degrees C. for a time interval of 1 to 72 hours.
7. The method of claim 6 , in which the post heating step is carried out under at least partial vacuum.
8. The method of claim 1 , wherein the organosilicon precursor comprises a linear or monocyclic siloxane.
9. The method according to claim 1 , wherein the oxidizing gas comprises O 2 present in a volume-volume ratio to the organosilicon precursor of from 0.01:1 to 0.5:1.
10. The method according to claim 1 , wherein Ar is present as the inert gas.
11. The method according to claim 1 , wherein the gas comprises from 1 to 6 standard volumes of the organosilicon precursor, from 1 to 100 standard volumes of the inert gas, and from 0.1 to 2 standard volumes of O 2 .
12. The method according to claim 1 , wherein both Ar and O 2 are present.
13. The method according to claim 1 , wherein the resulting coating has a roughness when determined by AFM and expressed as RMS of from 7 to 20 nm.
14. The method according to claim 1 , additionally comprising a step for preparing a barrier coating on the substrate before the lubricity coating is applied, the additional step comprising:
(a) providing a gas comprising an organosilicon precursor and an oxidizing gas in the vicinity of the substrate surface; and
(b) generating plasma from the gas, thus forming an SiO x barrier coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD).
15. The method according to claim 14 wherein in the step for preparing a barrier coating
(i) the plasma is generated with electrodes powered with sufficient power to form an SiO x barrier coating on the substrate surface; and
(ii) the ratio of the electrode power to the plasma volume is equal or more than 5 W/ml; and/or
(iii) the oxidizing gas comprises O 2 in a volume:volume ratio of from 1:1 to 100:1 in relation to the silicon containing precursor.
16. The method according to claim 1 , wherein the substrate is a polymer selected from the group consisting of a polycarbonate, an olefin polymer, a cyclic olefin copolymer (COC), a cyclic olefin polymer (COP), and a polyester.
17. The method according to claim 1 , wherein the plasma is generated with RF energy.
18. The method according to claim 1 , wherein the plasma-forming energy reduces the breakout force, F i , of the syringe, compared to the breakout force of a similar syringe that has only been treated at the second energy level.
19. The method according to claim 1 , wherein the resulting lubricity coating has an atomic ratio Si w O x C y or Si w N x C y wherein w is 1, x is from about 0.5 to about 2.4, y is from about 0.6 to about 3.
20. A coated substrate coated with a lubricity coating made by the method according to claim 1 .
21. The coated substrate of claim 20 , wherein the lubricity coating has a lower frictional resistance than the uncoated surface by at least 25%.
22. A syringe comprising a barrel made according to claim 1 .
23. The syringe according to claim 22 which contains in its lumen a medicament.
24. The syringe of claim 22 , wherein the plunger initiation force F i is from 2.5 to 15 N and the plunger maintenance force F m is from 2.5 to 25 N after 1 week.
25. The method of claim 1 wherein the lubricity coating has the atomic ratio Si w O x C y wherein w is 1, x is from about 0.5 to about 2.4, y is from about 0.6 to about 3.
26. The method of claim 1 , wherein the plastic substrate is COP, wherein the gas in step (a) comprises octamethylcyclotetrasiloxane, O 2 and Ar, and wherein the power for generating the plasma is from 6 W/ml to 0.1 W/ml in relation to the volume of the syringe lumen.
27. A method for preparing a lubricity coating on a plastic substrate, the method comprising:
(a) providing plasma enhanced chemical vapor deposition (PECVD) equipment;
(b) in the plasma enhanced chemical vapor deposition (PECVD) equipment, providing a gas comprising an organosilicon precursor, optionally an oxidizing gas, and an inert gas in the vicinity of the substrate surface;
(c) in the plasma enhanced chemical vapor deposition (PECVD) equipment, generating plasma in the gas by providing plasma-forming energy adjacent to the plastic substrate as a first pulse at a first energy level; and
(d) after step (c), in the same plasma enhanced chemical vapor deposition (PECVD) equipment, without breaking vacuum, generating plasma in the gas by providing plasma-forming energy adjacent to the plastic substrate as a second pulse at a second energy level lower than the first energy level;
thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD).
28. The method of claim 1 , in which the first pulse is applied for 0.1 to 5 seconds and the first pulse energy level is from 21 to 100 Watts.