Lubricant coating and medical injection device comprising such a coating
The invention relates to a lubricant coating ( 5 ) for a medical injection device ( 1 ), comprising successively: —a bottom layer ( 50 ) in contact with the medical device surface ( 21 ) of the container to be lubricated, comprising a mixture of cross-linked and non-cross-linked poly-(dimethylsiloxane), —an intermediate layer ( 51 ) consisting essentially of oxidized poly-(dimethylsiloxane) and having a thickness comprised between 10 and 30 nm and, —a top layer ( 52 ) consisting essentially of non-cross-linked poly-(dimethylsiloxane) and having a thickness of at most 2 nm. The invention also relates to a medical injection device comprising such a lubricant coating, and a manufacturing process for said coating.
1. A lubricant coating for a medical device, comprising:
a bottom layer in contact with a surface of the medical device to be lubricated, comprising a mixture of cross-linked and non-cross-linked poly-(dimethylsiloxane);
an intermediate layer consisting essentially of oxidized poly-(dimethylsiloxane) and having a thickness between 10 and 30 nm; and
a top layer consisting essentially of non-cross-linked poly-(dimethylsiloxane) and having a thickness of at most 2 nm.
2. The lubricant coating according to claim 1 , wherein the bottom layer is a gel.
3. The lubricant coating according to claim 1 , having a thickness between 90 and 400 nm.
4. The lubricant coating according to claim 1 , wherein the thickness of the bottom layer is between 58 and 388 nm.
5. The lubricant coating according to claim 1 , wherein the formula of the oxidized poly-(dimethylsiloxane) of the intermediate layer is:
[SiO(CH 3 ) 2-x (OH) x ] n ,
where x ranges from 0.2 to 1.5 and n is an integer.
6. The lubricant coating according to claim 5 , wherein x=0.75.
7. The lubricant coating according to claim 5 , wherein n ranges from 70 to 100.
8. The lubricant coating according to claim 1 , wherein the thickness of the intermediate layer is between 15 and 25 nm.
9. A process for manufacturing a lubricant coating, comprising:
depositing a layer of poly-(dimethylsiloxane) on a substrate, the thickness of said layer being between 90 and 400 nm; and
exposing said layer to an oxidizing plasma, so as to form said lubricant coating by oxidizing and cross-linking at least part of the poly-(dimethylsiloxane),
wherein said oxidizing plasma is carried out in an atmosphere comprising oxygen and argon,
wherein the atmosphere of said oxidizing plasma contains oxygen and argon with respective partial pressures between 15 and 30% for oxygen and between 70 and 85% for argon, and
wherein the step of exposing is an exposure between 10 and 40 seconds.
10. The process according to claim 9 , wherein a viscosity of the deposited poly-(dimethylsiloxane) is between 900 and 1200 cSt at 25° C.
11. The process according to claim 9 , wherein the oxidizing plasma is generated by radio-frequency, with a power ranging from 50 to 300 W, and under a vacuum in the range 1.33-13.3 Pa (10-100 mTorr) in absolute value.