Solid material comminution or disintegration – Processes – With heating or cooling of material
Reexamination Certificate
1996-02-07
2001-12-04
Rosenbaum, Mark (Department: 3209)
Solid material comminution or disintegration
Processes
With heating or cooling of material
C241S065000, C241S260100
Reexamination Certificate
active
06325307
ABSTRACT:
The inventions relate to the field of grinding of materials, particularly, to the methods and devices for producing powder from polymeric material and can be applied to grinding of natural and synthetic polymeric materials in the form of friable crumb, scrap, fibers, real silk, and ultra-high-modulus fiber, among others.
It is known a prior art process [A. A. Blagonravova, A. I. Nepomniashii “Lacquered epoxy resins”, “Khimia”, Moscow, 1972, pp. 207-208.] for producing polymer powders including the mixing of components of a polymer composition at temperature providing the formation of a melt, and at pressure of 0.3-50 MPa, the cooling of a melt down to solidification temperature and subsequent grinding to the powdery state. With this process initially coarse crushing for achieving the particle size not more 3 mm, is carried out, and followed by the mechanical fine grinding, by impact, for instance. This process allows to produce powders from brittle materials, which can be transferred into molten state. However, many of the materials (lint, high-strength fibers of real silk etc., for instance) cannot be transferred into molten state. Besides, the process is unsuitable for the materials with high viscoelastic properties.
Also a device is known for producing powder from polymeric materials [Patent of Switzerland 412294, Cl.a,1/12.] which comprises a casing having therein a cylindrical chamber, a grinding rotor being mounted coaxially within said chamber. Between a side surface of a grinding rotor and an internal surface of a cylindrical chamber a grinding zone is positioned. The grinding rotor is provided with grinding means of cutting and impact type, whereas the surface of the chamber is constructed with triangular shape longitudinal grooves, which have small orifices for the passage of a powder. The casing is provided with inlet and outlet openings.
The device does not allow to produce powder from natural leather, foamed polyurethane, high-modulus and ultra-high-modulus fibers, as the design of the device does not provide the mechanical densification of these materials, the latter being a necessary condition for their disintegration.
It is known a method [Inventor's certificate of U.S. Ser. No. 1213612, Int.CI B 29 B 1/12, Bull.Inv. N41-2, 1993, p.195] for producing powders from thermoplasts including the heating of thermoplasts up to temperatures 3-40° C. lower than that of their softening, accompanied by subsequent action of pressure (0.5-100 MPa) and shearing (0.5-50) during simultaneous cooling down to temperatures 3-600 lower than that of a heating.
The method allows to produce fine powders from polyethylene and some other thermoplasts with relatively low energy consumption. However, pulverization of elastic materials, such as high-strength fibers of real silk, aromatic polyamides, cotton and some other high-strength polymers with reasonably loose structure as well as monolithic elastic materials is not feasible. These materials are of high elasticity that hinders or rules out their crushing and grinding under the action of pressure and shearing. Besides, the heating of polymeric materials with low heat conductivity using external heat sources cannot be realized fast enough, resulting in reduction of productivity of a grinding process.
The device for producing powder from polymeric material is known [Inventor's certificate of U.S. Ser. No. 1120587, Int.CI B 29 B 1/12.Bull.Inv. N41-42, 1993, p.195] which comprises casing with inlet and outlet openings. Within the casing a rotor in a shape of a body of revolution with annular clearance towards the inner surface is located, between end faces of a rotor and casing a radial-circular slot being formed, which communicates with the annular clearance. The device is provided with cooling means of rotor and/or the inner surface of the casing, and in the zone of the radial-circular slot it is provided with a heating member of casing. The inlet opening of the device is hermetically joined to the casing.
Said device provides the preparation of fine powders from low density polyethylene and some other polymer thermoplasts as well as their composites. The melt of these thermoplasts easily penetrates into the circular slot between rotor and casing and forms during cooling a reasonably monolithic solid material, in the interior of which high shear stresses are realized, leading to its crushing and grinding. At the same time, said device gives no way to grind virtually all kinds of polymers with fibrous and porous structure, thermoplastic ones, such as twisted fosta nylon, for instance, and non-thermoplastic as well. To introduce this type of materials into an annular clearance of said device is a very difficult task, and these materials which possess poor heat conductivity and low elasticity, are heated too slowly, being introduced into the clearance, through the external heat sources and, furthermore, in the interior of the material only slight, if any, shear stresses are realized. Because of it these materials are just conveyed lengthwise of the clearance towards outlet, i.e. by-passing the grinding stage.
An object of the present inventions is the development of a highly efficient method allowing to produce powder from polymeric material with loose and fibrous structure, as well as from monolithic materials, which are in elastic state, in particular, and also an apparatus design through which this method could be realized.
The solution of this task is attained by applying a method for producing powder from polymeric material, including its heating and subsequent grinding under the action of pressure and shearing from 0.5 up to 50 at simultaneous cooling. In said method the heating Is effected up to temperatures 30-250° C. in two stages, namely, initially at a pressure increasing from 0.1-0.5 MPa up to 3-100 MPa, and afterwards under isobaric conditions at shearings 0.3-10 during 0.3-10 sec; grinding is performed as the pressure is decreased to 0.1-0.5 MPa.
The solution of the task is attained also by applying a device for producing powder from polymeric material comprising a grinding chamber which is designed as a casing provided with inlet opening and discharging hopper, a grinding rotor having a shape of a body of revolution with annular clearance towards the inner surface of the casing is mounted coaxially within said casing, the device being provided with cooling means of rotor and/or of the casing. Said device is equipped with a compacting chamber, disposed in alignment with and prior to the grinding chamber, said compacting chamber being designed as a cylindrical casing with charging hopper and outlet opening, and with a compacting screw with helical channels at its side surface, the depth of said channels being gradually reduced towards outlet opening, said compacting screw being mounted within the casing of compacting chamber in order to convey the material towards the grinding chamber. At the side surface of said compacting screw, at its end, positioned near outlet opening of compacting chamber, and/or at the side surface of said grinding rotor, at its end, positioned near inlet opening of said grinding chamber, a ring-shaped boring 1-8 mm in depth in its shallow section is cut. The compacting screw is butt-jointed with said grinding rotor with the possibility of their independent or cooperative rotation, or said compacting screw is made integral with said grinding rotor.
The term shallow section is used in reference to that region of the ring-shaped boring, where it is of a minimum depth. The inner side surface of the compacting chamber and/or grinding chamber in the zone of the ring-shaped boring can be designed with bosses and/or hollows, in the shape of longitudinal grooves or ribs, for instance.
At the inner surface of the grinding chamber casing two threads in the shape of helical channels with constant and/or variable depth are performed, including forward threading cutted in one direction, and counter threading cutted in the opposite direction, the latter intersecting r
Aleksandrova Liudmila Borisovna
Baliberdin Vladimir Nikolaevich
Gorkov Dmitrii Alekseevich
Khaliavin Igor Ivanovich
Mashinskaya Galina Pavlovna
Gaia International, LLC
Rosenbaum Mark
Smith , Gambrell & Russell, LLP
LandOfFree
Method for producing powder from polymeric material and... 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 powder from polymeric material and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing powder from polymeric material and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2586889