| Nanocarbon-producing device -> Monitor Keywords |
|
|
 
Nanocarbon-producing deviceRelated Patent Categories: Chemistry Of Inorganic Compounds, Carbon Or Compound Thereof, Elemental Carbon, Fiber, Fabric, Or Textile, ProductNanocarbon-producing device description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070025905, Nanocarbon-producing device. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a nanocarbon producing apparatus. BACKGROUND ART [0002] Recently technological application of nanocarbon is actively studied. The nanocarbon means a carbon substance having a nanoscale fine structure, typified by a carbon nanotube, a carbon nanohorn, and the like. Among others, the carbon nanohorn has a tubular structure in which one end of the carbon nanotube formed by a cylindrically rounded graphite sheet is formed in a circular conic shape. Usually the carbon nanohorns aggregate in a form, in which the circular conic unit is projected from a surface like a horn while the tube is located in the center by Van der Waals force acting between circular conic units. The carbon nanohorn assembly is expected to be applied to various technical fields due to specific characteristics thereof. [0003] It is reported that the carbon nanohorn assembly is produced by a laser vaporization method of irradiating the carbon substance (hereinafter also referred to as "graphite target") of a raw material with a laser beam in an inert gas atmosphere (Patent Document 1). In Patent Document 1, a CO.sub.2 gas laser .degree. is illustrated as the laser beam. [0004] The CO.sub.2 gas laser has a wavelength of about 10.6 .mu.m, and ZnSe and the like are preferably used as a material which transmits the CO.sub.2 gas laser (Patent Document 2). Therefore, in producing the carbon nanohorn assembly with the CO.sub.2 gas laser, it is considered that the laser beam can be focused on a surface of the graphite target by using the ZnSe lens. [0005] [Patent Document 1] Japanese Laid-open patent publication NO. 2001-64004 [0006] [Patent Document 2] Japanese Laid-open patent publication NO. 2001-51191 DISCLOSURE OF THE INVENTION [0007] The invention studies the method of producing the carbon nanohorn assembly by providing a window made of ZnSe (also referred to as "laser beam window") in a producing chamber. Then, it is found that a weight ratio (hereinafter referred to as "yield") of the carbon nanohorn assembly is decreased in a recovered soot-like substance as an operating time of the laser beam window is lengthened. A lifetime of the laser beam window is relatively shorter, and sometimes the laser beam window failed. As a result, it is found that the apparatus is expensive to maintain and the lifetime of the apparatus becomes shorter. For the ZnSe lens provided outside the chamber, the lifetime is also relatively shorter. [0008] Therefore, the reason why the yield of the carbon nanohorn assembly is decreased and the reason why the lifetime of the laser beam window or the lens is short are studied. As a result, in irradiating the graphite target with the laser beam, the soot-like substance created from carbon vapor generated from the graphite target adheres to a surface of the laser beam window, and it is found that the adhesive soot-like substance is a possible cause of the reasons. When the soot-like substance adheres to the surface of the laser beam window or the lens, it is also clear that the laser beam window or the lens is heated by generating light absorption in the portion to which the soot-like substance adheres. [0009] In such cases, there is a possibility that an optical path is shifted by a thermal lens effect. The shift of the optical path may shift a radiation position of the CO.sub.2 gas laser in the surface of the graphite target or cause a change in power density of the light with which the surface is irradiated. It is speculated that this is the reason why the yield is decreased as the operating time of the apparatus is increased. Further, it is speculated that the heating of the laser beam window or the lens causes the failure and the like. Therefore, the technology in which the carbon nanohorn assembly is produced without decreasing the yield of the carbon nanohorn assembly is required. In order to lengthen the apparatus lifetime, the technology different from the conventional technology is required. [0010] The present invention is performed in view of the foregoing circumstances, an object of the invention is to provide a technology in which the nanocarbon is stably obtained at high yield. Another object of the invention is to provide a technology in which the lifetime of the nanocarbon producing apparatus is lengthened. [0011] The inventor actively has studied on a technique of obtaining the nanocarbon at high yield. As a result of that study, the inventor finds it important that the optical member is shielded from the adhesion of the soot-like substance when the graphite target surface is irradiated with the light outgoing from a light source using the optical members, and the inventor reaches the invention. Further, the inventor finds that the optical member is protected from the adhesion of the soot-like substance by not directly irradiating the graphite target surface with the light outgoing from the light source, but by irradiating the graphite target after the light is reflected to change the optical path, and the inventor reaches the invention. [0012] According to the invention, there is provided a nanocarbon producing apparatus characterized by including a graphite target; a chamber which accommodates the graphite target; a window unit which is provided in a part of the chamber; a light source which irradiates light onto a surface of the graphite target through the window unit; a recovery unit which recovers a nanocarbon generated from carbon vapor, the carbon vapor being vaporized from the graphite target by the light irradiation; and a shielding member which is located between the window unit and the graphite target. [0013] In the invention, the shielding member is provided between the window unit and the graphite target. As described above, in the case of the configuration in which the surface of the graphite target is directly irradiated with the light after the light outgoing from the light source is transmitted through the window unit, the soot-like substance obtained from the carbon vapor generated from the surface of the graphite target also flies in a direction in which the soot-like substance returns to the window unit side, so that the soot-like substance is easy to adhere to the surface of the window unit. Therefore, in the case where the optical member made of ZnSe is used, the optical member is easy to be heated. [0014] On the contrary, in the configuration of the invention, the window unit is configured to be shielded from the surface of the graphite target. Therefore, even if the soot-like substance generated from the surface of the graphite target flies onto the window unit side, since the window unit is shielded by the shielding member, the soot-like substance which is moved toward the window unit to adhere to the surface thereof is suppressed. Accordingly, the power density of the light with which the graphite target is irradiated can be stabilized to stably produce the nanocarbon having the desired property at high yield. [0015] In the invention, the shielding member is arranged such that the window unit is shrouded against the carbon vapor vaporized from the graphite target. The shielding member can be configured to keep the window unit shrouded so as not to adhere the soot-like substance obtained by the carbon vapor generated from the graphite target surface while causing the light outgoing from the light source to reach the graphite target surface. [0016] In the invention, the chamber accommodates the graphite target. However, the whole of the graphite target may not be accommodated. A part of the graphite target may be accommodated. [0017] In the invention, the window unit is the optical member which transmits the light outgoing from the light source. For example, the laser beam window or the lens and the like can be used as the window unit. The window unit is arranged while a part of the window unit is exposed to the inside of the chamber. The window unit may be arranged in an outgoing end face of the light source or the like in the form of a part of the light source, or arranged in a wall surface of the chamber, in which the graphite target is accommodated, in the form of the member independent of the light source. [0018] In this specification, the term "power density" means the power density of the light with which the graphite target surface is actually irradiated, namely, the power density at a radiation region of the light in the graphite target surface. [0019] In a nanocarbon producing apparatus of the invention, an optical member for introducing the light to the surface of the graphite target may be included between the window unit and the shielding member. Therefore, the graphite target surface can securely be irradiated with the light, which allows the nanocarbon to be stably produced. In the invention, since the shielding member is provided between the optical member and the graphite target, the soot-like substance which flies in the direction of the window unit without recovering by the recovery unit to adhere to the surface of the optical member can be suppressed. Therefore, the radiation position shift of the laser beam in the graphite target surface caused by the thermal lens effect or the fluctuation in power density of the light in the surface can be suppressed, which allows the nanocarbon having the desired property to be produced stably and continuously. Accordingly, the yield of the nanocarbon can be improved. Since the heating of the optical member is suppressed, the failure of the optical member can be suppressed to lengthen the lifetime of the optical member. The increase in maintenance cost of the apparatus due to exchange of the optical members can be suppressed. Therefore, the apparatus configuration having the excellent endurance and productivity can easily be realized. [0020] According to the invention, there is provided a nanocarbon producing apparatus characterized by including a graphite target; a chamber which accommodates the graphite target; a window unit which is provided in a part of the chamber; a light source which irradiates light onto a surface of the graphite target through the window unit; a recovery unit which recovers a nanocarbon generated from carbon vapor, the carbon vapor being vaporized from the graphite target by the light irradiation; and a reflecting member which reflects transmitted light transmitted through the window to introduce the transmitted light to the surface of the graphite target. [0021] In a nanocarbon producing apparatus of the invention, the optical member may include a reflecting member. Continue reading about Nanocarbon-producing device... Full patent description for Nanocarbon-producing device Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Nanocarbon-producing device patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Nanocarbon-producing device or other areas of interest. ### Previous Patent Application: Preparation of a composition comprising an alkaline earth metal oxide and a substrate having a reduced amount of grit Next Patent Application: Method and installation for the manufacture of carbon nanotubes Industry Class: Chemistry of inorganic compounds ### FreshPatents.com Support Thank you for viewing the Nanocarbon-producing device patent info. IP-related news and info Results in 0.21417 seconds Other interesting Feshpatents.com categories: Tyco , Unilever , Warner-lambert , 3m 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
