Disclosed herein is a method of forming a graphic image having the appearance of three-dimensionality, the method comprising the steps of: providing a preformed lenticular film having a flat side and having a side with lenticules opposite the flat side; and printing an image on the flat side of the lenticular film using web fed printing to produce a graphic image web in which the perceptible image possesses photographically acceptable quality, wherein the image elements are printed on the lenticular film at an angle which corresponds to the pitch of the lenticules of the lenticular film.

It is known in the art to fabricate generally planar display devices which include an image sheet and a lenticular lens sheet which, in combination, give the image and appearance of three dimensionality. The lenticular lens sheet and the image sheet must be aligned properly to avoid a distorted image. The components have heretofore been in sheet form because the process of combining them is usually manual to ensure necessary registration.
The illusion of three dimensionality requires the image originally be made with a special three dimensional or stereoscopic camera, photographing the desired object from a plurality of angularly displaced positions. Such a camera typically uses a photosensitive film disposed behind a lenticular screen. The lenticular screen is positioned adjacent the photosensitive film so the focal point of each lenticule generally coincides with the front surface of the film. Thus, the image of the object is focused into a narrow image band which is exposed in the film. As the camera is shifted to the next angular position, the lenticular screen is also shifted slightly. A subsequent picture image of the object from the new angular position is then exposed into a separate image band in the film adjacent the preceding image band. Each time the camera is moved to a new angular position, the object is photographed and the image is exposed in the film as a similar, narrow image band adjacent the previously formed image band, until a series of image bands representing different views of the object is created. To avoid overlap of image bands, the lenticular screen is only moved a distance equal to the width of a single lenticule as the camera is moved through its full angular range. This collection of image bands, which is formed under a single lenticule, may be called an image element. Each image element is approximately the width of a single lenticule and includes all of the condensed views of the object.
Cameras of this type are disclosed in Stockbridge et al., U.S. Pat. No. 3,380,360, issued Apr. 30, 1968 and Bonnet, U.S. Pat. No. 2,508,487, issued May 23, 1950. Both of those patents disclose three dimensional or stereoscopic cameras used to photograph objects from numerous angular positions where the photograph taken at each position is exposed on a film as a linear image band.
Once the object is photographed from tile various positions, the film may be developed the same as any other photographic film, but the resulting image is a compilation of the numerous adjacent image bands. Each image band represents the object from a given angle, albeit in a focused or compressed form. This can provide the overall image with a somewhat distorted look to the naked human eye. However, when the developed image is combined with a lenticular screen or sheet having lenticules of approximately the same size and focal length as the lenticular sheet used to expose the film, the image becomes clear to the human eye as viewed through the screen.
The lenticular sheet must be placed over the image elements so the focal point of each lenticular lens coincides with the front surface of the image sheet. The image will appear to be three-dimensional because the observer is viewing the image through the lenticular sheet from a slightly different angle due to the lateral spacing between his eyes. In effect, this allows each eye to focus on a different image band, representing different views of the photographed object from separate angles, thereby giving the viewer the illusion of a three dimensional image.
In the past, the lenticules and image elements were relatively wide and each lenticule had to be perfectly aligned over each image element to obtain a clearly, defined three dimensional image. It has been difficult to obtain precise alignment and impossible to mass produce three dimensional images efficiently and economically. Typically, the lenticular sheet has beer manually positioned over the image sheet and then carefully adjusted to eliminate moire line or interference. This is a time consuming, inefficient and expensive task.
Further difficulties exist in mass producing three dimensional sheets for use in publications such as magazines due to the size of the lenticules and the consequent thickness of the lenticular lens sheet. However, larger lenticules have longer focal lengths and necessitate a thicker lens overlay so the focal point of the lenticule is approximately adjacent the image elements on the image sheet. This, of course, leads to a relatively thick composite sheet which is not suitable for magazines or other printed media that require a thinner sheet dimension. Making the sheet sufficiently than to be used in magazines requires the lenticules to be extremely small thus making it more difficult to form the lenticular lens sheet and properly align it with the image sheet. The required precision has made the use of efficient, high output machinery difficult.
It has long been desirable but unattainable to make both the image sheet and the lenticular lens sheet in continuous form and then combine them at a rapid pace with precise registry to produce a finished product having photographically acceptable quality. Standard printing methods could then be used to reproduce the images in continuous form. Though techniques have been developed for creating a lenticular lens in continuous form, and certain methods and devices have also been used in an attempt to combine an image web with a continuous lenticular lens, none of these devices is able to produce a thin, flexible lenticular image composite for economical use in the production of, for example, magazines while maintaining the precision necessary to produce quality images having the illusion of three dimensionality without interference lines or distorted appearance.
In three patents to Conley, U.S. Pat. Nos. 4,420,502, issued Dec. 13, 1983, 4,414,316, issued Nov. 8, 1983, and 4,420,527, issued Dec. 13, 1983 an apparatus and method for making a composite sheet material are disclosed. A transparent base web is directed onto the surface of a first roll and advanced along an arcuate path around the first roll and then through a narrow gap disposed between the first roll and a second roll. Before the transparent base web passes between the first and second rolls, a flowable, uncured actinic radiation-curable thermosetting resin is directed onto the web behind the narrow gap. The second roll includes grooves so that, as the resin covered web passes through the narrow gap and around the second roll, lenticular formations are made in the flowable resin. Ultraviolet radiation is directed through the transparent basis web and into the flowable resin layer while it remains in contact with the second roll. Thus, the flowable resin is cured into a composite lenticular lens sheet.
Such a process can produce small, well defined lenticular lenses. However, the difficulty remains in properly joining such a lenticular lens with a corresponding image web in a manner that avoids distortion of the image. Typically, the lenticular lens will still need to be cut in sheets and then carefully aligned by hand with a corresponding image sheet. It would be advantageous, and meet the long-felt need summarized above, if such a lenticular lens could be precisely aligned and combined with the corresponding images while the image sheet and the lenticular lens both remained in continuous form. This would greatly increase the efficiency and volume of the finished web resulting in a very economical product.
Other patents disclose methods and devices for making lenticular lens products but none with the accuracy or precision that would allow the finished product to be used in typical publications such as magazines. For instance, Jerothe et al., U.S. Pat. No. 3,264,164, issued Aug. 2, 1966, discloses a device which makes a laminated, flexible fabric-like material having interesting characteristics of color and depth. However, precise accuracy is not necessary since one of the purposes of the patented device is to produce images having a moire effect. Additionally, that approach uses colored lines and various colored shapes placed at different depths between cumulative flexible sheets. In the Jerothe et al. device, a relatively thick sheet is used for the formation of the lenticular lens. The lenticular lens sheet is laminated with various films and the resulting laminate passes between a pressure roll and a gravure roll where surface ribs or lenticular lens type ribs are formed by pressing the relatively thick lens forming sheet against the gravure roll. That device, however, cannot be accurately controlled to make extremely small accurate lenses in alignment with the image bands of an image web to yield photographically acceptable image quality.
Leach, U.S. Pat. No. 3,565,733, issued Feb. 23, 1971 discloses an apparatus for making a composite web from paper web combined with melted plastic. In Leach, a paper web, which can include an image, is passed between a pressure roll and a coating roll and then around a chilled embossing cylinder. A melted plastic is poured onto the coating roll which brings the melted plastic into contact with the paper web. This combined paper web and melted plastic is immediately brought into contact with the surface of the chilled embossing cylinder which solidifies the melted plastic leaving lenticular lens-type formations in plastic. A problem with the Leach apparatus is that it does not provide for the precision alignment of the lenticular lens formations with the image elements on the image web. This prevents the constant replication of high quality images having the appearance of three dimensionality without distortion. Additionally, meltable plastic will not retain its proper shape under the rigors of magazine use and shipping which can tend to place the lenticular lens formations under harsh conditions of pressure and heat. Once the lenticular lenses degrade, the three dimensional effect is lost. See also U.S. Pat. No. 3,607,340 to Stroupe issued Sep. 21, 1971.
In Lemelson, U.S. Pat. No. 3,146,492, issued Sep. 1, 1964, an apparatus is disclosed which produces a multiple image sheet display on a continuous basis. In Lemelson, an impressionable sheet is laminated with a plurality of sheets and then passed through a pair of rolls. One of the rolls is an embossing roll which creates lenticular formations in a face of the impressionable sheet. The apparatus is similar to those mentioned above in that it is difficult to form precision lenticules in the solid web without which an image of photographically acceptable quality cannot be reliably and repeatedly reproduced. Additionally, there is no way for the machine to provide precise alignment of the image elements with the lenticules.
The present invention addresses the foregoing drawbacks involved in making a precision lenticular lens image web having three dimensional image characteristics with photographic quality.


A mobile cremation urn includes a container portion having a volume in which cremation ashes are stored and a mounting portion coupled to the container portion to secure the mobile cremation urn to a moving vehicle. The container portion may be elongated and the mounting portion may be oriented substantially parallel with the container portion or a longitudinal axis thereof. The mounting portion may include a mounting flange, mounting posts, or mounting apertures. A removable closing member may be attached to the container portion and may seal the ashes contained therein. The closing member may also include a locking feature. The container may be fabricated with a corrosion resistant coating. A distinguishing mark may be displayed on an exterior surface of the container.

Cremation urns are containers that are used to hold the cremated remains of living beings. Cremation is an alternative to earth burial or entombment for the final disposition of the body of the deceased. It is a process by which the body is reduced to ashes by heat and fire. The remains may be placed in a cremation urn, which can be buried much like a full size casket. Sometimes, friends and family of the deceased may scatter the ashes in a sentimental location. However, in many instances, the cremation ashes may be memorialized in a home, a columbarium, a mausoleum, or other fixed location where the urn is displayed.
Keepsake urns are another type of urn designed for those wishing to memorialize the deceased. Jewelry is one type of keepsake urn that allows loved-ones to carry a portion of the cremated remains as a memento or to give a small amount of the remains to others. Jewelry and these types of keepsake urns are portable, which offers a different way to memorialize the deceased. However, these types of keepsake urns are discrete, delicate items often noticeable and sentimental mostly to those wearing the item. Others who see the keepsake may not understand or appreciate its significance.
It should always be remembered that memorialization serves as a tribute to a life lived and provides a focal point for remembrance of the deceased. For some people, memorialization that contemplates a fixed display or a piece of jewelry worn on a person does not reflect the true nature and spirit of the deceased. In some cases, the deceased may have been a part of an organization having a large following or that is well known or well respected. Also, the deceased may have been an avid outdoorsman, traveler, or motorcyclist who is not representatively memorialized through an urn that is displayed in a fixed manner or worn on a person's body. Conventional urns do not appear to address the desire for persons, friends, and families to transport cremation ashes in a manner similar to they way the deceased lived their lives.


A tank-cleaning device, having a housing (1) insertable into an opening of a tank, which housing has a rotationally fixed housing part (2) communicating with an ink for the cleaning fluid and a nozzle holder (4) rotatable relative to the rotationally fixed housing part (2) about a first pivot axis (5), and having at least one nozzle assembly with four nozzles (8, 9, 10, 11) that is disposed on the nozzle holder (4) rotatably about a second pivot axis (7), while having a simple structure, enables thorough cleaning of tanks with narrow tank openings, if two nozzles at a time (8, 9; 10, 11) of the nozzle assembly (6) are disposed at an acute angle (12) to one another in the form of respective V-formations (13, 14), and the two V-formations (13, 14) have essentially opposed directions (15).

The invention relates to a tank-cleaning device, having a housing insertable into an opening of a tank, which housing has a rotationally fixed housing part communicating with an ink for the cleaning fluid and a nozzle holder rotatable relative to the rotationally fixed housing part about a first pivot axis, and having at least one nozzle assembly with four nozzles that is disposed on the nozzle holder rotatably about a second pivot axis.
A similar tank-cleaning device is known from European Patent Disclosure EP 0 430 659 A2. This known tank-cleaning device has a slender housing, which can be introduced even into a narrow tank opening. The nozzle assembly has only two nozzles, which are disposed at an angle of 180xc2x0 to one another. When the housing is introduced into a narrow tank opening, the nozzle assembly is rotated in such a way that the common axis of the two nozzles is parallel to the longitudinal axis of the housing. The tank opening therefore has to have an only slightly greater diameter than the slender housing of the tank-cleaning device. A small tank opening can advantageously be manufactured much more economically than a large one.
On the inside surface of the tank, during the cleaning operation, the two nozzles create a certain netlike spray pattern, which at a fixed, predetermined ratio of the two rotary motions about the two aforementioned pivot axes is always repeated after a certain number of rotations and has a fixed xe2x80x9cmesh widthxe2x80x9d. The paths traced on the inside surface of the tank by the fluid streams come to have a fixed density, which cannot be increased even by providing a long cleaning period, since the fluid streams always travel along the same paths.
In other known devices, the cleaning density has therefore been reduced by the disposition of four nozzles instead of two nozzles. The four nozzles in the known nozzle assemblies are always disposed at uniform angular intervals of 90xc2x0 each from one another. The reason for this is that in the known tank-cleaning devices, the nozzles rotate uniformly about a typically horizontally disposed pivot axis, while the entire nozzle assembly rotates uniformly about a typically vertical pivot axis. Given the equal 90xc2x0 angular spacings of the nozzles, the result is accordingly a uniform spray pattern without major gaps on the inside surface of the tank.
The known nozzle assemblies with four nozzles have the disadvantage, however, that when they are introduced into a narrow tank opening, not all the nozzle axes can be adjusted parallel to the longitudinal axis of the housing anymore, or at least not unless further complicated engineering provisions are made. With very narrow tank openings, one is therefore forced to shorten the nozzle length, but this leads to a poorer quality of the fluid stream and less-effective cleaning, with poorer outcomes of cleaning. This means in turn, however, that so far, there has been no tank-cleaning device with four nozzles that fits through a narrow tank opening and nevertheless furnishes a fluid stream that attains effective cleaning.
The object of the present invention is therefore to disclose a tank-cleaning device which with a simple structure permits thorough cleaning of tanks with narrow tank openings.
This object is attained according to the invention in that two nozzles at a time of the nozzle assembly are disposed at an acute angle to one another in the form of respective V-formations, and the two V-formations have essentially opposed directions.
Surprisingly, it has been found that with the arrangement of nozzles in V-formations that form an acute angle, in accordance with the invention, a uniform spray pattern without major gaps can be created. If this nozzle assembly is rotated such that one V-formation points upward and the other points downward, then the longer dimension of the nozzle assembly is oriented in the direction of the longitudinal axis of the housing. The minimum required diameter of the tank opening is then determined only by the housing width and by the slenderer dimension of the nozzle assembly.
In a preferred embodiment, it is provided that the rotation of the nozzle holder about the first pivot axis and the rotation of the nozzle assembly about the second pivot axis are mechanically coupled to one another and have a fixed ratio to one another, so that the spray pattern repeats after a certain number of revolutions, and that the acute angles of the V-formations are adapted to the ratio of the two rotations with a view to a uniform spray pattern. If the ratio of the rotations is fixed, then by a skilled selection of the acute angle a uniform spray pattern without major gaps can be created that does not substantially differ from the spray pattern of known tank-cleaning devices that have four nozzles each disposed at right angles.
If the first pivot axis coincides with the longitudinal axis of the housing and is disposed perpendicular to the second pivot axis, and if the ratio of the two rotations is 45:43, then with a view to a uniform spray pattern it is optimal that the acute angles of the V-formations amount to approximately 40xc2x0. With this arrangement of the pivot axes, uniform rotary motions can be generated by simple means. It can be calculated that at the aforementioned ratio of the two rotations, the following angles between the nozzles can be considered for attaining a uniform spray pattern: 90.00xc2x0; 81.63xc2x0; 73.26xc2x0; 64.88xc2x0; 56.51xc2x0; 48.14xc2x0; 39.77xc2x0; 31.40xc2x0; 23.02xc2x0; 14.65xc2x0; and 6.28xc2x0. The angle of 39.77xc2x0 chosen here, or in round numbers 40xc2x0, represents an advantageous compromise with a view to a uniformly dense spray pattern with the smallest possible tank opening.
The provision that the two V-formations are disposed symmetrically to one another, so that two nozzles at a time point in opposite directions also contributes to the uniformity of the spray pattern.
If the two V-formations are disposed offset from one another, so that their pointed tips are each radially spaced apart from the second pivot axis, and the connecting line between the two pointed tips is substantially perpendicular to the angle bisector of the two acute angles, then the nozzles can be embodied advantageously long while optimally utilizing the little installation space available, so as to improve the quality of the fluid stream and the effectiveness of the cleaning.
If a turbine and a gear for driving the rotatable nozzle assembly are disposed in the elongated and slender rotationally fixed housing part in such a way that the cleaning fluid flowing in under pressure from the ink flows through the housing and drives the turbine before it emerges from the nozzles, then a slender device is obtained which is suitable for introduction into narrow tank openings and includes a simple drive mechanism for the two rotary motions, so as to assure thorough, uniform cleaning of the inside surfaces of the tank.
The invention can be improved still further in that an angular play of approximately 180xc2x0 is provided between an element that drives the rotary motion of the nozzle assembly about the second pivot axis and the drive shaft of the nozzle assembly. As a result, in the range of the angular play, an alignment of the nozzle assembly longitudinally of the housing is made possible from any arbitrary rotary position, without having to activate the rotational drive mechanism. It is therefore possible for a nozzle assembly that may not be positioned correctly to be aligned by hand for insertion into a narrow tank opening, without having to rotate the drive elements as well, and without unnecessarily using up the cleaning fluid otherwise required for drive purposes.
In an advantageous feature of the aforementioned angular play, the drive shaft is provided with a pin, which protrudes radially past its outside diameter and engages a recess, extending in the direction of rotation over an angular range of 180xc2x0, in the hub region of a cone wheel supported rotatably on the drive shaft.
Another advantageous feature provides that a platelike baffle connected to the drive shaft in a manner fixed against relative rotation, in the hub region, has a first protrusion protruding axially inward and extending in the direction of rotation over an angular range of 90xc2x0; that a cone wheel rotatably supported on the drive shaft, in the hub region, has a second protrusion protruding axially outward, counter to the first protrusion, projecting in the same axial region as the first protrusion and extending in the direction of rotation over an angular range of 90xc2x0, so that the relative rotation between the platelike baffle and the cone wheel is limited to an angular range of 180xc2x0 by the protrusions stopping against one another in the direction of rotation. The protrusions can be integrally molded in a simple way during production, in particular simultaneously with the casting of the cone wheel and baffle, with requiring further work steps such as inserting a pin into the drive shaft.


A process for cleaning a wastewater stream which comprises soot and is obtained in the preparation of acetylene, the soot being present in finely divided form in the wastewater, wherein the soot is removed by subjecting the wastewater to a solid concentration by sedimentation and then the soot sludge obtained in the sedimentation is dewatered further by a pressure filtration.

The present invention relates to an improved process for removing soot from a wastewater stream which is obtained in the preparation of acetylene, the soot being present for the most part in finely divided form.
Acetylene is prepared industrially, inter alia, by the process which has been developed by BASF and is based on partial oxidation of hydrocarbons (preferably natural gas) with oxygen. It is described, for example, in U.S. Pat. No. 5,824,834 and in "Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2000, Electronic Release, Chapter 4.2.1".
The two feedstocks, hydrocarbon and oxygen, are first preheated, to from approx. 500 to 650° C. in the case of use of natural gas, then they are mixed and only then are they converted in the firing chamber in a flame which is stabilized by the so-called burner block. Preheating and premixing are required for high acetylene yields.
The flame reaction at temperatures above about 1500° C. is quenched by spraying water in after a few milliseconds, i.e. the very rapid cooling to approx. 90° C. terminates the free-radical chain reaction in the flame. This prevents the degradation of the thermodynamically unstable acetylene intermediate. The reaction product is the so-called cleavage gas, which is a mixture of acetylene, crude synthesis gas (mainly H2 and CO), steam and by-products. One of the by-products in this case is soot. Upstream of the compression, the cleavage gas is cooled typically to approx. 30-50° C. in order to condense the majority of the steam and hence to reduce the amount of gas to be compressed.
The soot formed as a by-product is found to be troublesome in the subsequent process stages and, to enhance the effectiveness of the process, efforts are therefore made to remove it from the cleavage gas.
The removal is effected predominantly by scrubbing the soot-containing gas with water, which, according to the process, gives rise to wastewater—often also referred to as "soot water"—with soot content from about 0.1 to 3% by weight. What is found to be particularly problematic in this context is that the soot is present for the most part in finely divided form; the size of the soot particles is typically in a range from a few nanometers to millimeters. The primary particles formed in the high-temperature zone of the acetylene synthesis have a diameter of from 20 to 300 nm. According to the process conditions in the acetylene synthesis, these primary particles may agglomerate to give particles up to 1 mm in size, generally particles from 0.001 to 0.05 mm in size.
The soot particles may be suspended in the soot water or else float on the surface unwetted by the water. Further constituents of the wastewater to be cleaned may be hydrocarbons and inorganic salts such as sodium salts. Sodium hydroxide solution is generally added in order to neutralize organic acids which form in the process and in order thus to prevent corrosion. As a result, the pH is usually in the range from 7 to 10.5.
Owing to the small particle size and the fine distribution of the soot, the direct removal of the soot particles from the wastewater of the acetylene preparation by means of filtration apparatus is found to be complicated and unsatisfactory with regard to its effectiveness in the known processes. DE-A 3528598 discloses a process for cleaning a soot-containing wastewater stream which stems from a high-temperature process. In this case, an additive such as calcium carbonate or lime hydrate is added to the wastewater in considerable amounts (from 2 to 10 kg/m3 ), then a flocculant is supplied and, immediately thereafter, the wastewater thus pretreated is subjected to a filtration, a gravity filtration being followed by a pressure filtration (claim 1). With regard to the cleaning of a soot-comprising wastewater stream from the acetylene preparation, this process is, however, found to be disadvantageous. For instance, the two-stage filtration requires complicated apparatus such as a belt filter which, as well as high procurement costs, also entails increased cost and inconvenience with regard to maintenance and energy demands. The concept of the directly linked two-stage filtration also leads to the disadvantage that, in the case of varying occurrence of wastewater to be cleaned or in the event of bottlenecks in one process stage, it is not possible here to react flexibly; the possibility of buffering and decoupling these process steps would be desirable. An additional complicating factor is that the filtercake obtained from the gravity filtration, owing to the elevated solids content, can already be handled only with difficulty, the effectiveness of the process being restricted further by the fact that the concentration of soot in this filtercake is reduced by the additionally supplied solid additives such as calcium carbonate. It is also disadvantageous that the amount of filtercake to be disposed of is increased by the additionally supplied additives such as calcium carbonate. This leads to a higher level of apparatus complexity in order to store the additives (reservoir vessel) and to meter them (control of the metering rates).
It is thus an object of the invention to provide an improved process for cleaning a wastewater stream which comprises soot and is obtained in the preparation of acetylene, the soot being present in finely divided form in the wastewater, which avoids the disadvantages mentioned and which enables removal of the soot in an effective manner which is simple from a process technology point of view with a high level of operational reliability, while enabling flexible reaction to varying operating conditions. At the same time, a solid residue which can be disposed of either by incineration or landfill disposal should be obtained.
Accordingly, a process has been found for cleaning a wastewater stream which comprises soot and is obtained in the preparation of acetylene, the soot being present in finely divided form in the wastewater, which comprises removing the soot by subjecting the wastewater to a solid concentration by sedimentation and then further dewatering the soot sludge obtained in the sedimentation by a pressure filtration.
The inventive concentration of the soot water is effected by means of gravity in conventional sedimentation vessels, for example thickeners or lamella clarifiers. The thickening achieves soot sludges with solid concentrations in the range from 1 to 4% by weight, preferably from 2 to 3% by weight. The soot sludge obtained by the sedimentation can advantageously be conveyed with a displacer pump, preferably an eccentric screw pump. The advantage of this inventive embodiment is that the sedimentation device and the pressure filtration can be set up in a spatially separate manner. Moreover, the sedimentation vessel can simultaneously serve as a soot sludge buffer in the case of appropriate dimensioning. The necessary clarifying area of the sedimentation vessel is dependent on the soot concentration present in the wastewater and on the volume flow. The charge based on the clarifying area is typically in the range from 0.5 to 5 m3/m2*h, preferably from 0.5 to 3 m3/m2*h. Hydraulic residence times of from 1 to 2 hours should be observed. The sedimentation vessel consists generally of a cylindrical part and a lower conical part which promotes the soot sludge discharge. The angle of the cone is preferably in the range from 70° to 100°, preferably 90°.
The ratio of diameter to height is in the range from 1:1 to 1:3, preferably from 1:1 to 1:1.5.
As a result, it is possible to react flexibly to varying solid loads, to use batchwise pressure filtration and to perform maintenance work in the subsequent process stages with simultaneously continuing occurrence of soot water, as a result of which the effectiveness of the process according to the invention is significantly enhanced.
The soot sludge obtained in the sedimentation is subsequently subjected to a pressure filtration in a dewatering apparatus. Preference is given to transporting the soot sludge from the sedimentation stage to the pressure filtration stage by means of a displacer pump. Dewatering apparatus recommended for the performance of the pressure filtration is batchwise apparatus such as chamber filter presses, membrane filter presses or continuous screening belt presses.
To improve the dewatering, it is additionally possible to mix a flocculant (F) into the soot sludge. The preferred amounts of flocculant are in the range from 0.5 to 5 g/kg of solid. The metered addition of the flocculant is effected preferably in the form of a solution; this can be done, for example, upstream of the charging pump and upstream of the dewatering apparatus, or preferably downstream of the charging pump and immediately upstream of the dewatering apparatus. For this purpose, a mixing device as described, for example, in EP 0710625 B1 is recommended in order to obtain a readily dewaterable, flocculated suspension.
The organic flocculants used may be commercial brands. These are water-soluble compounds based on acrylamide or acrylic acid. In the process according to the invention, anionic flocculants are found to be particularly suitable. The required amounts of flocculent are in the range from 1 to 10 g of active substance/kg of soot. The flocculants are used preferably as aqueous solutions having concentrations of from 0.05 to 0.2%. The metered addition of the flocculant solution upstream of the inventive sedimentation can be effected directly into the soot water line. Very good mixing can be effected either by means of a static mixer or a separate stirrer vessel.
Useful charging pumps have been found to be particularly eccentric screw pumps (piston membrane pump, compressed air membrane pump). Pumps, for example centrifugal pumps in which high shear forces occur in the liquid, are unsuitable. The degree of deposition on chamber filter presses is at least 95% of the soot to be removed. In the case of screening belt presses, 90% can be achieved. Filtrate contaminated with soot particles can be recycled into the sedimentation stage for further clarification.
The filtercakes obtained are solid and brittle and have solids contents of from 20 to 30% by weight, preferably 23-25% by weight. The consistency of the filtercakes satisfies the requirements of landfill deposition. The disposal of the filtercakes obtained in an appropriate incineration plant is often the more economically viable solution as a result of their energy content (calorific value).
A further object of the invention consists in fully dispersing floating soot in the wastewater by means of a pretreatment.
Moreover, it should be possible to substantially remove hydrocarbons dissolved in the process from the soot water.
Soot fractions which, owing to their chemical or physical properties, float on the water surface are preferably suspended by the use of a suitable surfactant upstream of the sedimentation in order to achieve substantially complete deposition of the soot solids in the sedimentation vessel. These are water-soluble macromolecular compounds which are prepared by alkoxylation of predominantly linear fatty alcohols and which, as surface-active substances, improve the wettability of the soot particles. In the process according to the invention, nonionic products which have good wetting properties with respect to hydrophobic substances are found to be particularly suitable. In order not to impair the operation of the subsequent process stages, the surfactant should have a very low foaming tendency. The advisable amounts of surfactant are in the range from 1 to 10 g/kg of soot. The metered addition of the surfactant upstream of the sedimentation can be effected directly into the soot water line. Very good mixing is effected either by means of a pump, a static mixer or a separate stirrer vessel. Should the foam formed by the addition of surfactants disrupt the operation of the process according to the invention (in the sedimentation or the pump), the foam formation can be reduced effectively with the aid of defoamers known to those skilled in the art.
Adsorbable organic hydrocarbons present in the wastewater stream may, if required, advantageously be reduced upstream of the sedimentation by addition of activated carbon (AC). The dissolved organic compounds are adsorbed on the activated carbon. The activated carbon is eliminated from the wastewater together with the soot in the pressure filtration stage. A favorable activated carbon dosage has been found to be an amount of from 5 to 15 g of AC/g of DOC (dissolved organic carbon). The exact requirement for activated carbon in the particular case can be determined by the person skilled in the art by recording an adsorption isotherm. The activated carbon is preferably added to the soot water as an aqueous suspension in a concentration of from about 10 to 20% by weight in a stirred vessel.
In order to improve the filtration properties of the soot sludge in the pressure filtration (increase in the filter area loading; achievability of a minimum dry substance content in the filtercake), a filtration assistant can be added to the soot water. Suitable substances for this purpose are especially inorganic substances, for example ash from an incineration plant. The necessary conditioning amounts are in the range from 0.1 to 1 kg of assistant/kg of soot. This filtration assistant can be added upstream of the sedimentation or upstream of the pressure filtration.
The process according to the invention offers an effective type, which is simple from a process technology point of view, of cleaning a soot-laden wastewater stream which stems from acetylene preparation. With a low level of apparatus complexity, removal of the soot is enabled here, while additionally allowing flexible reaction to varying operating conditions, which further enhances the effectiveness of the process according to the invention.

Process for separating off carbon black from a wastewater stream


A multiply durable laminated cookware unit includes components having a ferrous steel core ply roll plated with second and third aluminum plies which are softer and anodic relative to the core ply and which are bonded to the core ply under pressure so as to provide exposed surfaces on the unit which exhibit the properties of rolled solid aluminum sheets. The exposed edge of the steel core can be protected by drawing at least one of the softer anodic aluminum cover sheets such that it extends beyond the harder steel core and the extended portion of the aluminum sheet is folded over the steel core to seal the edge end of the steel core therebeneath.

This invention relates to cookware and, more particularly, to durable laminated cookware components of roll plated multiply construction.
In my U.S. Pat. No. 3,788,513 laminated cookware constructions are disclosed in which inexpensive mild or carbon steel is employed as a core ply which is covered by thin plies of aluminum and/or other non-ferrous materials. These laminates minimize the use of the latter relatively expensive materials without detracting from the ability to fire the cookware at or near aluminum annealing temperatures for the purpose of sinter bonding porcelain enamels or sintered non-stick coating anchor frits to the container and without an attendant loss of container strength as the result of exposure to high sintering temperatures.
The present invention is directed to laminated cookware having all of the advantages of the construction as disclosed in U.S. Pat. No. 3,788,513 but offering additional advantages and improved performance features. In the present invention, cookware units are cold formed of a laminate in which the opposite sides of a steel core ply, such as for example a sheet of inexpensive carbon steel of deep drawing quality, are roll plated, clad or otherwise pressure bonded with sheets of commercially pure aluminum or sheets of aluminum alloys suitable for cookware use. Such novel cookware units made of roll plated laminated sheets of carbon steel and aluminum, which are suitably pressure bonded together, offer several advantages over utensils or cookware made of solid metal or other multiply materials, e.g. dip coated, spray coated or electrically deposited. The term roll plated as employed herein is intended to include laminate combinations which are made by pressure bonding sheets of carbon steel and pure aluminum or aluminum alloys suited for cookware.
Carbon steel cookware is susceptible to rust, unless protected with a suitable impervious coating. For this reason solid stainless steel or aluminum cookware is in widespread use. As noted in U.S. Pat. No. 3,788,513, although stainless steel cookware has a long life, it also exhibits inferior thermal conductivity and is much more expensive than either carbon steel or aluminum cookware. Accordingly, the more moderatedly priced aluminum utensils are popular.
Regardless, however, of the price, metal cookware should (1) withstand rusting or other corrosion to provide a long service life and prevent contamination of food, (2) be easily cleaned both inside and outside, and (3) have a sufficiently aesthetic appearance. In addition, cookware should also exhibit various thermal and mechanical properties such as noted in U.S. Pat. No. 3,788,513. For these reasons, uncoated metallic cookware must provide polishable surfaces which must be thoroughly polished to provide smooth surfaces which are free of crevices and pits both on the interior as well as the exterior of the utensil.
If the interior cooking surfaces are not smooth, food particles settle rapidly into even the smallest microscopic pits and crevices which make the utensil uncleanable, either by the normal cleaning procedures employed by the housewife or by dishwashing machines. The remnants of caked-on food particles promote the attraction of new particles to the unclean metal during successive cooking and will rapidly render the cookware unhygenic, unappetizing and stained and pose health risks to the members of the household, unless the utensil is thrown away. Disposal, in turn, produces ecologically undesirable solid wastes and necessitates the premature repurchase of replacements.
The exterior of uncoated utensils must also be polished for several reasons. First, it is not uncommon during cooking that food contents overrun the rim. Such overruns tend to cake onto the hot and usually dry exterior of the utensil firmly and instantaneously. Such caked-on food remnants are practically unremovable, unless the exterior surfaces of the pot are smooth and free of crevices or pits. Aside, however, from this functional prerequisite, it is also a commercial fact that the exterior of uncoated utensils must be polished because consumers buy only clean and shiny uncoated utensils. Thus, uncoated cookware must be formed of material which is at least as polishable as rolled solid aluminum sheet, unless additional organic or inorganic coatings are applied on the utensils.
A great majority of metal cookware is formed of stamped, pressdrawn, spun or otherwise cold formed solid flat sheets. Rolled solid aluminum sheets with a commercial "mill finish" or prepunched discs thereof are both polishable and are available to the cookware industry and are suited for such forming operations. The surfaces of these sheets are free of pits, burrs, crevices or slates which easily loosen, rupture or delaminate in cold forming. When viewed under a microscope, the surfaces of such solid sheets exhibit grooves which are arranged in the direction of rolling. However, the depth of these grooves is only microscopic and thus polishability is not impeded. Observation with a similar microscope also shows that the surface of a "roll plated" laminate of steel and aluminum sheets, to which the present invention is directed, is substantially identical with that of a solid rolled aluminum sheet, and thus the polishability of such laminate is at least as good as that of rolled aluminum sheets proper. Moreover, no discernable difference exists in appearance to the naked eye between rolled solid and laminate sheets after polishing with conventional polishing equipment.
In contrast to the smooth and homogeneous surfaces of solid aluminum sheets and to those of "roll plated" laminates of sheets of steel and aluminum, schistous, inhomogeneous, castlike and porous aluminum layers are exhibited on the surfaces of sheets covered by methods other than roll plating. Therefore, the polishability of cookware made of the latter sheets is vastly inferior as compared to cookware made of either solid aluminum or of "roll plated" laminates, the latter of which is subject of this invention. Cookware made of "roll plated" laminates will at least match the life, cleanability and appearance of solid, uncoated aluminum utensils and will be vastly superior as compared to uncoated utensils made of sheets covered by methods other than roll plating.
In one form of prior art cookware, a "tri-component" utensil wall structure is purported to be formed of a "hot-dip" aluminized composite steel core sheet. Such "hot-dip" wall structure consists of an approximate 0.9 mm thick steel core and two aluminum layers, each of approximately 25 microns or 1 mil in thickness, covering the opposite faces of the steel core. Actually such "hot-dip" prior art cookware is formed of a material known commercially as "aluminized steel" and, as such, is not a "tricomponent" at all, but is a "quint-component". Specifically, an AlFe layer interface is formed between the steel core and its aluminum cover layers in "aluminized steel". This AlFe interface is both intentionally and inherently formed during the "hot-dip" aluminization of steel sheets to form this "quint-component" wall structure of such "aluminized steel" cookware. In contrast, the "roll plated" laminates of sheets of steel and aluminum of the present invention are of true "tri-component" wall construction and such AlFe interfacial layer is neither discernable nor measurable in these "roll plated" laminates.
One important drawback of the presence of the AlFe interfacial layer in the "aluminized steel" wall structure is the reduction in the effective thickness of the already thin aluminum layers to, at maximum, 18 microns, and frequently substantially lesser thicknesses. This lost aluminum thickness, moreover, can not be recovered by applying more aluminum during the dipping process, since any additional aluminum applied by this method substantially reduces the ability to draw or otherwise mechanically form the sheet material into the finished cookware shape, due to an increase in the likelihood of delamination of the aluminum and steel. These drawbacks are avoided by the "roll plated" laminate construction of the present invention.
The more homogeneous, pore-free and the thicker the aluminum cover layers on a steel core are, the more completely will corrosive attack be arrested and thus the longer lasting and more effective will be the protection of the rust prone steel core against corrosion. The castlike structure of aluminum in the "aluminized steel" which is deposited at random on the steel sheet by dipping, can not provide the pore free continuity and homogeneity of aluminum sheets or foils which are pressure bonded to the faces of a steel core by roll plating as in the present invention. Further the inferior resistance of "hot-dip" aluminized sheets to corrosion is further accentuated by press drawing, stamping and other cold forming steps as employed in the shaping of the cookware.
In shaping cookware, the limits of elastic deformation must be exceeded to effect the plastic deformation of the substrate. Rolled sheets of steel and aluminum of suitable properties, such as the "roll plated" laminates of the present invention, readily lend themselves to plastic deformation or "flowing" into the die with no adverse effects on the initially pore free continuity of the aluminum cover layers. In contrast, the castlike structures of the schistous and porous cover layers of "hot-dip" "aluminized steel" sheets are extremely prone to rupture, breaks, or tears, rather than to "flow" into the die when press drawn. Finally, and quite important, the substantial reduction in the aluminum thickness of "aluminized steel", substantially increases the likelihood of exposure of the steel core material through the already coarse, porous dipped aluminum layer.
In addition, the AlFe layers themselves in "aluminized steel" are highly brittle and thus lack the ductility essential for "flowing" in the press dies without ruptures and fractures. Another drawback of the AlFe interfacial layers increases the likelihood of corrosion due to the composition of the layers themselves. Metal substrates made by the "hot-dip" process exhibit various compositions of AlFe, such as Al.sub.3 Fe, Al.sub.5 Fe.sub.2, etc. When cookware having such interfacial substrates is used, the carbon in the steel core and the effect of elevated temperatures encountered during cooking can contribute to the development of aluminum-carbode compositions such as Al.sub.4 C.sub.3. Such aluminum-carbide compositions are highly unstable in the presence of water or vapors thereof without which very few cooking or dishwashing operations can be carried out. Cookware cold formed of "roll plated" laminates of sheets of steel and aluminum according to the present invention is substantially free of these AlFe interfacial layers and thus resist such corrosion.
Returning again to the subject of the thickness of the aluminum cover layers, this thickness will generally govern the corrosion resistance, life and value of the cookware. Since the thickness of the aluminum cover layers of a substrate formed by the "hot-dip" process is limited to approximately an 18 micron maximum as mentioned previously, the corrosion resistance, life and value of cookware made of "hot-dip" aluminized steel is substantially diminished. In contrast, the aluminum cover layers of the cookware of the present invention can be easily varied up to 10% of the thickness of the steel core. Not only is this important for the foregoing reasons, but such increased thicknesses also insures sufficient stability, without the excessive warp of the utensil and avoids spot heating which might burn the food.
The absolute minimum wall thickness of any metallic "top of the stove" cookware container is 0.7 mm. Thus, when the laminate of the present invention is employed, aluminum layers of up to 70 microns may be easily realized, which is 10% of the thickness of the steel core, and this thickness will not impede drawability, etc. In contrast, the maximum of only an 18 micron thickness is obtainable with dipped "aluminized steel" regardless of the core thickness.
In addition to the superior polishability, pore free homogeneity, superior cold forming or "flow" capability, and the much larger thickness of the aluminum cover layers of the roll plated cookware of the present invention, another extremely important feature of the present invention is its ability to be coated.
At the present state of the art, examples of some coating finishes are tabulated in Table No. 1 as follows:
TABLE NO. 1 __________________________________________________________________________ Cookware Type Interior Coating Comment Exterior Coating Comment __________________________________________________________________________ Press drawn carbon (a) 2-coat vitreous preferred (same as in- preferred steel sheet porcelain enamel. terior) do. (b) single coat "direct substandard (same as in- substandard on" procelain vitreous spall resis- terior) spall re- enamel. tance sistance Press drawn solid (c) high buffed polish- "hot dip" not (same as in- "hot dip" aluminum sheets or ed surface. suited terior) not suited aluminum covered steel sheets do. (d) single coat PTFE do. (same as interior do. dispersion on acid except PTFE is pickled aluminum. pigmented) do. (e) single coat PTFE dis- do. (same as interior do. persion on acid pickled except PTFE is aluminum and ceramic pigmented) anchor matrix is flame sprayed on metal under PTFE. do. (f) 2-coat pigmented do. PTFE system on grit blasted metal. do. (g) 2-coat pigmented do. PTFE system on grit blasted metal and cer- amic anchor matrix is flame sprayed on metal under PTFE do. (h) 2-coat pigmented do. PTFE system on grit blasted metal and vitreous frit anchor is deposited on blasted me- tal and heat bonded in excess of 500.degree.C. do. (i) same as next above life is sub- (j) single coat life is sub- coating, but vitreous standard where "direct-on" in- standard frit anchor applied on metal is "hot organic alumin- where unblasted, alkaline dip" um enamel on metal is micro-etched metal alkaline cleaned "hot dip" and heat bonded in ex- micro-etched cess of 500.degree.C. metal and heat bonded in excess of 500.degree.C. __________________________________________________________________________
Most non-stick coating systems for aluminum cookware interiors employ materials in the PTFE (polytetrafluorethylene) family. The most widely used application techniques of these coatings are set forth in Table No. 1, at (d), (f) and (h). Approximately half of the external coatings on aluminum cookware are of "direct-on", one coat vitreous porcelain enamel as set forth in Table No. 1, in (j). The other half of external coatings on aluminum cookware utilize an organic material as applied by the method set forth for interior coatings in Table No. 1, in (d).
It is highly desirable that cookware lends itself for the maximum number or ideally, of course, for all of the surface finishing possibilities which are available and in demand. The cookware made of solid aluminum or of "roll plated" laminates of sheets of carbon steel and aluminum as in the present invention perform identically to each other with respect to the abovenoted finishing possibilities and therefore the cookware of the present invention fulfills the requirement for diverse surface finishes. Conversely, cookware made of "hot-dip" aluminized steel sheets or steel sheets covered in a manner other than by roll plating, falls short of this requirement in most respects.
A PTFE finish is by definition a self-lubricating, non-stick coating. Thus, it is designed to resist adhesion to everything, which, unfortunately, includes the surfaces of the cookware which are intended to be coated with such material. The adhesion of a 25 micron strip of a PTFE top coat to a prime coated metal is only between 10 to 20 pounds as determined by the laboratories of du Pont de Nemours.
For purposes of cookware coatings, aqueous suspensoids of PTFE are used. These suspensoids can contain coloring pigments and various wetting agents, as well as certain inorganic constituents in so-called "prime-coat" preparates. A "PTFE dispersion" as employed herein, denotes such suspensoids which are free of inorganic constituents and are applied directly onto the metal as prepared for reception of the PTFE. A "PTFE top coat" as employed herein, denotes suspensoids which are applied over a "prime coat", rather than onto the metal directly. A "PTFE prime coat" as employed herein denotes such suspensoids which contain inorganic constituents, and may include other mentioned constituents, and which is applied directly to the metal as prepared for reception of the PTFE.
All three of these PTFE suspensoids are deposited on cookware by conventional paint application methods, usually by spraying. The wet film is then furnace "sintered" at a temperature range from 400 to 460.degree.C. At these temperatures, the aqueous carrier of the suspensoid and the wetting agents are volatilized and the PTFE particles form a film. Unlike thermosetting paints, PTFE particles do not form a film by crosslinking and, unlike thermoplastic paints, PTFE particles do not coalesce or "flow" together during heat bonding. It is only, in lieu of a better description, that the film forming mechanism of PTFE coatings is denoted by the term "sintering".
The tensile strength of a sintered PTFE film at room temperature is between 1500 to 3500 PSI, depending on thickness. (ASTM test D 638). The industry standards for non-stick cookware coatings call for a dry and free film thickness of only 25 microns, thus its strength is likely to be lower than these values.
A sintered PTFE film is soft, it scratches easily and thus it can abrade quite rapidly. In general, the life of such coatings is considerably shorter than the life of the metallic body of the cookware proper.
A sintered PTFE film is also ductile. Its elongation, at room temperature, is between 200 and 400 percent as determined by ASTM test No. D 638. A PTFE coated flat metal disc can thus be deep drawn into the form of a utensil without rupturing its finish.
A sintered PTFE film on cookware is also considerably and intentionally porous. Experiments and actual use tests substantiate that capillary liquids which are volatilized during cooking, tend to lift up PTFE films of low porosity from the metal.
Due to the intentional and necessary porosity of PTFE coatings, the metallic surface of the cookware underneath such coatings is exposed to the aggressive media of food contents in very much the same manner as the cooking surfaces of uncoated cookware. But while a slightly oxidized or corroded uncoated aluminum cookware may still be used without health hazard, any substantial interfacial corrosion between a PTFE coating and metal will cause the separation of the PTFE film and will render the non-stick cookware, as such, inoperative. Thus, it is at least as important to protect the metal interface from corrosion beneath a nonstick coating as it is to protect the surface of an uncoated utensil against corrosion. For the foregoing reasons the non-stick coating on cookware formed of "roll plated" laminates as in the present invention will have a life identical to solid aluminum cookware and both will provide a longer life than non-stick cookware covered by methods other than roll plating.
PTFE is inert to nearly all chemicals, except molten alkalis and a few perfluorinated compounds. Pure aluminum and aluminum alloys suitable for cookware contain no such constituents. Thus, during sintering the coating on the aluminum surface of the cookware, no known or discernable chemical reaction bonding occurs at the interface between the PTFE particles and the metal. A sintered film of "PTFE dispersion", can only be coupled mechanically to a metallic substrate, such as the aluminum surface of a cookware. Accordingly, this smooth aluminum surface must be made receptive to PTFE before the dispersion is spray-deposited.
In order to obtain a mechanical coupling between a film of "PTFE dispersion" and metal, and to assure a peel strength which meets industry standards, a controlled degree of cavities must be imparted into the initially smooth aluminum surface. The neck size of the intrusions of these cavities must considerably exceed the larges size PTFE particles in the dispersion and the intrusions then must widen to form flask-like ballooning cavities underneath the metal surface. Through their wide necks, a large number of anchor cavities can thus fill with the aqueous dispersions of PTFE before the water carrier evaporates. Then, during firing, the PTFE particles which fill the cavities beneath the metal surface, cohere into ball-shapes larger than the cavity necks, as well as cohere to the PTFE above the necks and on the metal surface through the necks of the anchor cavities. In this manner the PTFE film on the face of the cookware is bonded to the captured ball-shapes at a very large number of points on the film.
The method of imparting such flask-like ballooning cavities into aluminum sheets for coupling a PTFE film mechanically was devised by Tefal S.A. of France. The Tefal process consists of (1) masking all metal surfaces which are not to be PTFE coated, (2) cleaning of the unmasked aluminum surfaces, (3) immersion pickling of unmasked metal surfaces in concentrated aqueous solutions of hydrochloric and hydrofluoric acids, (4) immersing into a neutralizing solution, and (5) removing of the masking and thorough cleaning of the metal prior to spraying and firing the PTFE coating.
In commercially available dispersions, the size of the largest PTFE particles can reach 0.5 microns or more. Experience substantiates that the open necks of anchor or cavities underneath the aluminum surface should be approximately 10 times larger than this particle size to permit the intrusion of sufficient amounts of PTFE into the anchor cavities beneath the metal surface. The depth of the anchor cavities must be at least 5 times greater than the diameter of their necks to secure a sufficient PTFE flow by capillary action. This then demands that the metal be penetrated by the acid pickling media to a depth of 25 to 35 microns. Intrusions of such depths pose no problems in cookware made of either solid aluminum sheet or "roll plated" laminates which offer a minimum of 70 micron thick aluminum cover layers, since even where the cavity depth is 35 microns, a minimum of 35 micron aluminum thickness remains. However, cookware made of steel covered by other than roll plating are limited in thickness of the aluminum cover layers to only approximately 18 microns. Therefore, cookware of the latter wall construction is clearly inoperative for coupling and carrying PTFE coatings by way of acid pickled anchor cavities.
Due to several considerations with respect to the coupling of PTFE on an acid pickled aluminum, a "2-coat" PTFE cookware finish system was devised by du Pont de Nemours. In this 2-coat system, the aluminum surface is made receptive by grit blasting. Usually, non-ferrous abrasives of about 60 to 80 mesh are shot from close proximity onto the fully annealed surface of aluminum by blast guns powered with compressed air at approximately 100 PSI pressure.
The roughness of the blasted surface of the "2-coat" system should be 200 micro inches as measured by a "profilometer" or, as measured by a "permascope" which measures the height of the metal "peaks", should average 9.2 microns of "peak" height or "valley" depth on an area of approximately 100 mm.sup.2 of the metal surface. As is well known by those skilled in the cookware coating art, the deepest individual "valleys" in the soft aluminum will be approximately twice as deep as the average depth of "valleys" which result from the most careful blast. A deepest valley depth somewhat in excess of 18 microns poses no problem for non-stick cookware made either of solid aluminum or of "roll plated" laminates as in the present invention which provides a minimum thickness of 70 microns for the aluminum cover layers over the rust prone steel core. In contrast, cookware made of steel sheets covered by methods other than roll plating offer a maximum thickness of only 18 microns for the aluminum cover layers. Accordingly, in the latter, the metal substrate deepest valleys break through the aluminum cover layers and will free the way for the aggressive media in the food or dishwashing agents to attack the steel core and will rapidly render such cookware and its non-stick coating inoperative.
In approving a non-stick utensil for service, among other qualitative requirements, the peel strength of the non-stick film must meet industry standards, for example the internationally followed quality control and test procedures of du Pont de Nemours.
The Tefal system, which couples a "PTFE dispersion" onto an acid pickled face of aluminum, meets the peel strength standard by a purely mechanical coupling between PTFE and the substrate. The theoretical maximum of the peel strength of such mechanically coupled non-stick coatings is essentially equal to the tensile strength of the PTFE film.
In contrast, in the "2-coat" system -- or other PTFE multiple coat systems, a "prime coat" of low PTFE content is deposited on the cookware first and then a "top coat", which is richer in PTFE is applied over the "prime coat". The "prime coat" is deposited onto rough surfaces, such as either directly onto grit blasted aluminum or onto hybrid substrates, such as where a flame sprayed or heat bonded matrix is applied to the metal surface. Such surfaces lack the flask-like ballooning cavities of acid pickled aluminum and, thus, their mechanical coupling capability is inferior as compared to that of acid pickled aluminum. Therefore, the peel strength of a film of "PTFE dispersion" applied with no "prime coat", directly onto such blasted or hybrid surfaces will be substandard. The "prime coat" is intended to augment the mechanical coupling deficiency of these surfaces, so that the peel strength of the complete "2-coat" system meets industry standards.
Most cookware "prime coats" differ from "top coats" and from "PTFE dispersions" in the following major aspects: (1) generally prime coats contain less PTFE, (2) prime coats have inorganic constituents in addition to the organic constituents, (3) the thickness of prime coats on cookware is substantially less than that of top coats, and (4) prime coats are not sintered fully prior to spraying and firing the "top caot". The bonding mechanism between a PTFE prime coat and a cookware substrate is not exactly known. Electron microscopic and electron probe studies relative to the bonding mechanism of aluminum/-enamel systems show certain analogies, however, with the bond between "2-coat" PTFE systems and cookware substrates. These studies suggest that the predominant bonding mechanism is an interaction or diffusion of the inorganic constituents of the coating and the aluminum. In a system employing a frit matrix, the diverse inorganic constituents of the frit and the metal appear to interact or diffuse, on the one hand, and then the inorganic constituents of the PTFE prime coat and the hybrid substrate, appear to interact or diffuse, on the other hand. In order to achieve a suitable bond by such mechanism, the two coating materials, i.e. the frit matrix and PTFE "prime coat", must have sufficient "affinity" to interact or diffuse and at the same time, each of these two coating materials and the aluminum must also be able to interact or diffuse. The solid particles in both the frit and the PTFE prime coat are comparatively small. Thus diffusion among the constituents of coating materials can occur on a substantially larger area than the diffusion or interaction of coating materials and aluminum. Indeed, only in rare cases can product failures be traced to separation between the frit and the PTFE prime coat. The failures of most "2-coat" systems are predominantly separations between the metal and either the frit or the prime coat or both.
The above mentioned electron microscopic studies also suggest that diffusion of aluminum and inorganic constituents of its coatings is more intensive along the grain boundaries of a rolled metal sheet than over its grains proper. Therefore, the larger the percentage of the area of grain boundaries in the total area of the coated surface of the metal, the higher is the probability for obtaining a solid and uniformly strong bond of the coatings. In other words, inhomogeneity of the metal surface and coarse grains are archenemies of solid bonds and durable coatings.
Appropriately rolled and annealed aluminum sheets exhibit homogeneous and fine grained metallographic structures. The same is true for the cover layers of "roll plated" laminates as in the present invention, since these cover layers are rolled aluminum sheets. Both of these substrates thus fulfill the prerequisites of long life coatings. On the other hand, the schistous, porous, cast-like structure of the cover layers of aluminum steel, where the steel is covered by methods other than roll plating, do not meet this prerequisite. The inferiority of the latter substrate in sheet form is accentuated by the incapability of the crystal lattice of its aluminum cover layers to rehomogenize after cold forming the sheet into the shape of a utensil.
Press drawing causes plastic deformation of the metal sheet. The unavoidable result is coarse graining of the metal through the stretching of its crystal lattice. The most severe coarse graining and other distortions in the metallographic structure of aluminum cookware occurs in the vicinity of the transition between its bottom and side wall and at bulges above the "skirts" of covers. The crystal lattice of deep drawn aluminum should be rehomogenized by heating the cookware and cover rapidly to a temperature of approximately 280.degree. to 320.degree. C prior to the spraying of any coating, either frit or PTFE. In this respect, cookware made of both solid aluminum and "roll plated" laminates as in the present invention exhibit homogeneous and fine grain structures. Steel covered by other methods does not.
In summary, the cookware formed of a "roll plated" laminate of sheets of carbon steel and aluminum as in the present invention exhibits durability, life and other qualitative features equal to that of solid aluminum cookware and each finish or coating applicable on the latter is suited for the former. In contrast, cookware made of steel sheets covered with aluminum by methods other than roll plating will be either substandard or inoperative.
Another noteworthy feature of the cookware of the present invention is the ability of its metal substrate to be cold worked to protect the sheared edges of the mild steel core which would otherwise be exposed, for example, about the upper rim of the cookware container or around the "skirt" of the cover. Such edges must be sealed in some manner to prevent corrosion and rust which will occur during use of the cookware units.
One way in which these corrodible plies could be protected is by the use of rust proof rim elements or by coating electrolytically, galvanically or otherwise, the exposed edges of the steel core to prevent corrosion during use. Laminated cookware units of mild steel-stainless steel lamina have been employed in the past in which the exposed sheared end edge of the mild or carbon steel core is protected by drawing the harder stainless steel cladding material over the edge of the mild steel to seal the exposed edge. However, an important feature of these prior containers includes deforming the mild steel core which is softer than the external stainless steel plies. Accordingly, in these prior cookware units of mild steel-stainless steel laminate construction, the mild steel core ply is the ply which is primarily deformed during the edge sealing operation such that the mild steel core is drawn into a sharp knife edge which necessitates further fabrication steps of folding and other forming. Moreover, since the mild steel core in the sealed end product is anodic relative to the non-corrosible stainless steel ply which is to protect it in these prior constructions, electrochemical deterioration and corrosion of the mild steel will frequently occur during use, particularly if the stainless steel layer is broken in any manner.
In the laminated cookware unit of the present invention, an otherwise sheet edge of the rust prone mild steel core may be readily protected by the relatively inert aluminum cover sheet without deforming the steel core which is to be protected and without the need for further forming steps to neutralize sharp knife edges and the like. In the present invention, the exposed edge of the ferrous steel core may be protected simply by drawing the softer non-ferrous roll plated aluminum cover sheet such that a portion of the latter extends beyond the edge of the steel core and this portion is then folded over the exposed ferrous steel edge. Moreover, edge corrosion resistance is substantially enhanced, since the aluminum is anodic relative to the ferrous steel.
In a principal aspect of the invention, a laminated cookware unit component includes a first sheet comprising a ferrous metal core and pore free second and third cover sheets of aluminum or aluminum alloys suited for cookware. The second and third sheets are roll plated and bonded to opposite faces of the first sheet, the first core sheet being sandwiched between the second and third cover sheets. The second and third sheets may be polished or buff finished or, alternatively, the exterior or the interior or both of these sheets of the cookware unit may be coated.
In another principal aspect of the invention, a cookware unit includes an exposed edge and a protective covering overlies the normally exposed end of the first ferrous core adjacent the edge, the protective layer comprising a portion of one of the non-ferrous cover sheets being drawn to a length to extend beyond the end of the first steel core and folded over its end.
Another principal aspect of the invention involves a method for sealing the edge of a laminated cookware component having a first steel core which is subject to deterioration. The method includes the steps of drawing a second, softer cover sheet such that the cover sheet extends beyond the end of the first steel core adjacent the edge of the cookware component which is to be sealed, and this extended portion of the cover sheet is then folded over the end of the first core to seal the end beneath the folded over portion of the second sheet.
These and other objects, features and advantages of the present invention will be clearly understood upon consideration of the following detailed description.


An ankle-foot orthosis is made integrally from a thin, shaped lightweight material. The orthosis comprises a flat foot-supporting member for extending beneath the sole of a foot of a user, a calf abutment member for abutting the calf of the user, a narrow connecting member extending from the foot-supporting member at a location on one side, preferably the outer side, of the ankle of the user to the calf abutment member so as to interconnect the foot-supporting member and the calf abutment member, and a releasable fastener for fastening the calf abutment member to a leg of the user. The orthosis may be made by a method, in which a thermoplastic material with reinforcing fibers is arranged between opposite plastic films or foils in a desired mutual arrangement. Thereafter, the space defined between the opposite films is sealed, and air or gas is then removed from the sealed space so as to compact the material arranged therein and so as to form a blank. The blank thus formed is thereafter heated to a plasticizing temperature and formed into the desired shape.

1. Field of the Invention
The present invention relates to an ankle-foot orthosis made integrally from a thin, shaped lightweight material. Such orthosis is used for supporting the foot of a patient suffering from neurological disorders due to cerebral haemorrhage, tumours, radiation treatment or diseases, so that the patient may achieve an almost natural and dynamic gait.
2. Description of Prior Art
U.S. Pat. No. 5,897,515 discloses an orthosis of this kind made from carbon fibre reinforced plastic resin. The known orthosis comprises a foot plate for supporting the foot of the user and a frame part extending upwardly from the foot plate in front of and in contact with the tibia area of the leg of the user.
It is an object of the present invention to improve this known orthosis.
Thus, the present invention provides an ankle-foot orthosis made from a thin, shaped lightweight material and comprising a flat foot-supporting member for extending beneath the sole of a foot of a user, a calf abutment member for abutting the calf of the user, a narrow connecting member extending from the foot-supporting member at a location on one sidexe2x80x94preferably the outer sidexe2x80x94of the ankle of the user to the calf abutment member so as to interconnect the foot-supporting member and the calf abutment member without contacting the tibia area, and a releasable fastener for fastening the calf abutment member to a leg of the user.
Because the orthosis according to the invention does not comprise parts covering the front part or the tibia area of the leg of the user the orthosis according to the invention is less visible in use than the prior art devices. This feature is especially important when a female user wears a gown or skirt and uses the orthosis at the same time. Furthermore, the orthosis according to the invention is more comfortable in use than the orthosis disclosed in the above U.S. patent. The reason is that the known orthosis relies on contact with the tibia area, which is often tender or painful.
Preferably, the connecting member is connected to an arch part of the foot-supporting member at a location adjacent to the arch of the foot of the user and in front of the lateral malleole. From this position the narrow connecting member extend to the calf abutment member without passing the anterior or front side of the leg of the user. Thus, the connecting member preferably extends along a substantially helical path.
The connecting member is preferably relatively thin, narrow and stiff, while the calf abutment member is relatively broad and defines a relatively large abutment surface. Therefore, the narrow connecting member is preferably widening towards the calf abutment member, which is arched so as to define a calf abutment surface being substantially complementary to the shape of the calf of the user.
The releasable fastener used for fastening the orthosis to the leg of the user may be of any suitable kind and may, for example, comprise a skin adhesive, a clamp or the like. In the preferred embodiment the releasable fastener comprises a strap for interconnecting opposite ends of the calf abutment member. Thus, the calf abutment member and the strap may encircle the crus of the user, and tightening the strap may fasten the orthosis. The strap may be held in position for example by means of a Velcro fastener.
The orthosis according to the invention may be made from a thin material, such as sheet metal or plastic material. In the preferred embodiment, however, the orthosis is made from fibre-reinforced thermoplastic material. This allows for a lightweight and strong structure, and yet the form of the orthosis may to some extent be adapted to the individual user when the thermoplastic material is heated to a softening temperature. The reinforcing fibres may be of any type conventionally used in plastic materials. Preferably, carbon fibres, glass fibres or a combination of such fibres are used. The reinforcing fibres may form strands, layers or cloths. In these layers the fibres may extend in the same general direction, in two crossing directions or may be randomly distributed.
The arch part of the foot-supporting member may be located between a rear or a heel supporting part and a front or ball supporting part of the foot-supporting member, and the heel supporting part is then preferably more flexible than the ball supporting part. This may, for example, be obtained by including more layers of reinforcing fibres in the ball supporting part than in the heel supporting part. By varying the flexibility of the various parts of the foot-supporting member the user may obtain a more natural gait.
While it is important that the foot-supporting member is flexible the object of the connecting member is to maintain the foot-supporting member and the calf abutment member in a substantially fixed mutual position. Therefore, the connecting member is preferably substantially more stiff than the foot-supporting member. This may, for example be obtained by including more layers of reinforcing fibres in the connecting member than in the heel and ball supporting parts of the foot-supporting member.
At least some and preferably all of the layers of reinforcing fibres extending longitudinally within the connecting member may continue into the arch part of the foot-supporting member. This provides a good mutual connection between the connecting member and the foot-supporting member and also provides a desired reduced flexibility of the arch part.
The thermoplastic material forming the matrix material in which the reinforcing fibres are embedded is preferably one or more of the following materials: polyethylene, polypropylene, modified polyethylene terepthalate, polyamide, polyethylene terepthalate, polyether imide, polyether sulfone, and polyether ketone.
The orthosis according to the invention may be an undivided, unitary member. Alternatively, the orthosis may be made in two or more parts, which are subsequently interconnected permanently or releasably. As an example, the narrow connecting member may be divided into two parts, which are releasably interconnected, for example by means of a connecting member embracing adjacent ends of the said two parts of the narrow connecting member.
The connecting member may be adapted to allow the length of the narrow connecting member to be adjusted.
According to a further aspect the present invention provides a method of making an orthosis as described above, said method comprising positioning the thermoplastic materialxe2x80x94preferably in the form of fibres, films, granules, or the likexe2x80x94and the reinforcing fibres between opposite plastic films or foils in a desired mutual arrangement, sealing the space defined between the opposite films, removing air or gas from said sealed space so as to compact the material arranged therein and form a blank. Subsequently, the blank thus formed may be formed into a desired shape, for example in a mould. This shape may be retained by heating the blank to a plasticizing temperature and subsequently cooling the shaped article thus formed. Preferably, such heating and cooling takes place while the shaped article is still within the mould. The said plasticizing temperature is preferably sufficiently high to allow the reinforcing fibres to become embedded in the plasticized thermoplastic material forming a matrix material.
The melting point of the films enclosing thermoplastic material and the reinforcing fibres may have a melting point being higher than the melting point of the thermoplastic material forming the matrix material. In that case the opposite films may form an outer skin layer of the finished orthosis. If, however, the melting point of the films is equal to or lower than that of the thermoplastic material positioned therebetween the material of the films may migrate into or become combined with the thermoplastic matrix material.
The air or gas may at least partly be removed from the sealed space between the opposite films, when positioned within the mould so as to remove residual air or gas or gas released during heating the thermoplastic material. Thus, the blank may be positioned in a mould cavity defined between a pair of first and second mould surfaces. The first mould surface defining the desired shape may be formed by a relatively stiff mould wall, while the second mould surface may be formed by a flexible wall and the mould cavity may then be connected to a vacuum source so as to form the blank into the desired shape.
Alternatively, a blank or pre-form formed by fibres and thermoplastic material may be arranged within a mould cavity defined between a pair of separable mould parts. When the pre-form or blank has been positioned in the mould cavity and heated to a plasticizing temperature the mould parts defining the desired shape of the final orthosis are pressed together so as to force the pre-form to adopt the shape defined by the mould cavity surfaces. At least one of the mould parts may be made from an elastic or resilient material, such as silicon rubber.
In any of the methods for making the orthosis, in which the blank or pre-form is heated, such heating may at least partly be obtained by placing electrical conducting material within the blank or pre-form and by sending electric current through the conducting material. Such conducting material may comprise reinforcing fibres, such as carbon fibres arranged within the blank or pre-form.

Ankle-foot orthosis and a method for making the same