Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing silicon
Reexamination Certificate
2000-02-29
2001-03-27
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing silicon
C427S503000, C427S536000, C427S446000, C106S038220
Reexamination Certificate
active
06207621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates a method for producing a member having a high lubricative surface and a member having a high lubricative surface, and more particularly the same method and the same member preferably usable for metallic molds, magnetic heads, magnetic tapes, hard disks, floppy disks, pistons, products for micromachine, etc.
2. Description of the Prior Art
As a typical member having a high lubricative surface, there is a member comprising a given base material and a polytetrafluoroethylene (PTFE) material fixed on a surface of the base material. The PTFE material has a so high lubrication that the member is generally used for pistons, piston-rings, drills, bolts, nuts, dices, etc.
In the fixing of the PTFE material onto the surface of the base material, dry-processes which are typically PVD methods such as plasma polymerization, sputtering, and vacuum deposition, wet-processes which are typically coating methods such as electroless plating, dispersion plating, and electrodeposition, and complex methods of these dry-processes and wet-processes are currently proposed and practically used.
It is also suggested that in the case that the member having the high lubricative surface is worn away and the lubrication of its surface is degraded, the worn parts of the member are embedded by re-coating and thereby the member is made have lubrication.
However, the PVD methods such as the plasma polymerization, etc. require vacuum chambers which are expensive and complicate in operation. Accordingly, the production costs and the equipment costs are increased.
The wet-processes which are typically coating methods such as electroless plating, etc. require high temperature firing and long time treatment. Thus, the wet-processes restrict inevitably the sort of base material to be treated.
Even the base material usable for the wet-processes requires the optimum process for itself because the treatment such as firing for the base material is performed in a temperature range near its heat-resistant temperature. The fixing of the PTFE material onto a variety of base material requires vast equipment, resulting in the increase of the cost of the member having the high lubricative surface.
Moreover, large amounts of water and organic solvent are used in the wet-processes, which is not favorable with respect to the environment.
The PTFE material is needed to be produced from an expensive fluorine-based compound as its raw material. Thus, even if the above producing method is improved, the cost-increase of the member due to the producing of the PTFE material is not removed finally.
Moreover, even the above re-coating forms crater-like steps on the surface of the member, so that it has difficulty re-forming the surface uniformly flat and smooth. Thus, it is very difficult to give high lubrication to the worn surface of the member.
SUMMERY OF THE INVENTION
It is an object of the present invention to provide a method for producing a new member having a high lubricative surface without the above problems and different from the above conventional member and to provide the new member.
This invention relates to a method for producing a high lubricative surface comprising steps of:
preparing a base material,
hydrophilizing a surface of the base material, and
chemically reacting the surface of the base material with molecules of an organosilane having a long molecular chain and thereby forming on the surface of the base material a monomolecular film made of the organosilane having the long molecular chain.
This invention also relates to a member having a high lubricative surface comprising a base material and a monomolecular film made of an organosilane having a long molecular chain on a surface of the base material.
To iron out the above problems, this inventors has been intensely studied to develop a new member having a high lubricative surface, superceded from the lubricative member having the PTFE material on its surface.
As a result, they have found the following facts:
By irradiating, on a surface of a base material made of metal or ceramics, a vacuum ultraviolet light using an excimer lamp or a plasma such as an oxygen plasma, the surface is hydrophilized. Then, molecules of an organosilane such as a fluoroalkylsilane are deposited in a thickness of monomolucular film onto the surface. Just then, astonishingly, the substances constituting the base material are strongly coupled to the molecules of the organosilane through a dehydrating condensation reaction.
Moreover, it extremely decreases the surface free energy of the base material to coat the surface of the base material with a monomolecular film made of an organosilane having a long molecular chain such as a long perfluoroalkyl-chain or a long alkyl-chain and thereby the wearing characteristic of the base material is much improved.
According to the method for producing the member having the lubricative surface and the same member of the present invention, only the hydrophilizing treatment of the surface of the base material and the deposition of the molecules of the organosilane having the long molecular chain onto the surface of the base material enable the member having the surface with excellent wearing characteristic of extremely small friction force to be produced.
Thus, not only the problem of large cost in the dry-processes and the wet-processes is removed, but the restriction of the base material usable for the wet-processes is done. Moreover, although the expensive fluorine-based compound does not have to be used as the raw material of the PTFE material, the production cost of the member having the high lubricative surface can be much decreased.
Since the deposited molecules of the organosilane exists in monomolecular film and thereby has a thickness of molecular length-order, it can cover the surface of the base material without changing the shape of the surface. Thus, when the monomolecular film composed of the molecules of the organosilane is worn away, peeled off or destroyed and thereby the lubrication of the member having the monomolecular film on its surface is decreased, a new monomolecular film can be formed again uniformly flat and smooth by removing the damaged layer due to the wearing away, etc. through re-coating and thereafter forming the new monomolecular film, which is different from the conventional member having the PTFE material on its surface.
Accordingly, the member having the high lubricative surface can be semi-permanently used for metallic molds, magnetic heads, magnetic tapes, hard disks, floppy disks, pistons, products for micromachine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described in detail as follows: The method for producing the member having the high lubricative surface requires to chemically react the surface of the base material with the organosilane having the long molecular chain.
The length of the long molecular chain is not limited, on condition that the organosilane-monomolecular film is formed on the surface of the base material according to the present invention and thereby the surface free energy of the base material is decreased, resulting in improving the wearing characteristic. However, the lower limited value of the length of the long molecular chain is preferably 1 nm. Thereby, the covering ratio of the surface of the base material with the organosilane-monomolecular film can be much increased and the disorder of the molecular arrangement in the monomolecular film can be decreased, so that the wearing characteristic of the member can be much enhanced.
The upper limited value of the long molecular chain is not particularly limited, but preferably 5 nm, more preferably 2 nm. If the length of the long molecular chain is larger than the upper limited value, it becomes difficult to form the monomolecular film uniformly and thereby the surface free energy of the surface of the base material may not be decreased efficiently. Thus, the member having the high lubricative surface with excellent wearing characteristic may no
Hozumi Atsushi
Sugimura Hiroyuki
Takai Osamu
Howard Jacqueline V.
Nagoya University
Stevens Davis Miller & Mosher LLP
LandOfFree
Method for producing a member having a high lubricative... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing a member having a high lubricative..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing a member having a high lubricative... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2469276