The present invention relates to a sludge treatment plant in which sludge is flocculated and then dewatered to form a cake and a reject liquor is modified by recycling 3 to 40% of the reject liquor into the sludge immediately before the dewatering process.

This invention relates to processes and apparatus for dewatering sewage sludge so as to produce a cake and a reject liquor which can be a supernatant, filtrate or centrate.
A typical sewage treatment plant takes in raw sewage and produces solids and clarified water. Typically the raw sewage is treated in a primary sedimentation stage to form a primary sludge and supernatant, the supernatant is subjected to biological treatment and then a secondary sedimentation stage to form a secondary sludge and clarified liquor, which is often subjected to further treatment before discharge.
The sludges are usually combined to form a mixed sewage sludge which is then dewatered to form a cake and a reject liquor. The reject liquor is usually recycled to the head of the plant and the start of the process, i.e., fed back to the primary sedimentation stage or a preceding stage in the plant. Any water which is required in the plant, for instance for dissolving polymeric flocculant, is usually either potable water (from the local drinking water supply) or is clarified water from the secondary sedimentation stage, optionally after any subsequent treatment procedures.
It is standard practice to dewater the sludge by mixing a dose of polymeric flocculant into that sludge at a dosing point, and then substantially immediately subjecting the sludge to the dewatering process and thereby forming a cake (typically having a solids content of 15 to 35%) and a reject liquor. The dewatering process may be centrifugation or may be by processes such as filter pressing or belt pressing.
The process is generally conducted so as to obtain the highest possible cake solids, preferably accompanied by the highest possible reject liquor clarity. It is well established that, for any particular performance parameter (such as cake solids) there is an optimum dosage of flocculant and that increasing the dosage above this optimum does not result in an improvement but instead tends to result in overdosing and in deterioration of performance. Accordingly, it can be assumed that polymer applied at dosages of up to the optimum is substantially all adsorbed on to the sludge so as to participate in bridging flocculation, whereas overdosing of polymer is liable to introduce additional polymer into the sludge with the result that excess polymer may remain in the reject liquor and the presence of this excess can interfere with the bridging flocculation performance.
There is a maximum solids loading rate (kg dry matter per hour) and a maximum hydraulic loading rate (liters sludge per hour) which can be handled in any particular dewatering apparatus. It has conventionally been regarded to be desirable normally to operate as close as reasonably practicable to the maximum solids loading rate, and in order that this can be achieved without exceeding the hydraulic loading rate it is necessary that the sludge which is dewatered should have a solids content within an appropriate range. If the sludge would normally have a solids content below this, it is conventional to subject it to a thickening stage (often promoted by the use of polymeric flocculant) before dosing the polymeric flocculant into the resultant sewage sludge substantially immediately prior to the final dewatering intended to form the cake and the reject liquor.
When setting up a dewatering process, it is therefore generally necessary to select the optimum dose and the optimum solids loading rate and hydraulic loading rate.
Thus the optimum combination of solids and hydraulic loading rates is selected to give the most efficient utilisation of the dewatering apparatus having regard to the sludge that is being dewatered. Thereafter, in most cases, it is generally undesirable to dilute the sludge since that increases the hydraulic loading rate without increasing dewatering efficiency.
In other processes, the sludge which is to be dewatered may have a solids content which is too high for optimum results, for instance because the viscosity of the sludge is such that it is difficult to achieve efficient mixing of the flocculant into the sludge and/or to achieve efficient distribution of the flocculated sludge in the dewatering apparatus. Under these circumstances, it is necessary to dilute the sludge prior to dosing the polymeric flocculant into it. The water which is used for dilution is usually the same water as is used for other purposes in the overall plant, namely either water from the drinking water supply or clarified water from the plant.
Various proposals have been made in the literature for recycling various streams to various points in a sewage treatment plant (additional to the normal recycling of the final reject liquor to the head of the plant, as discussed above).
For instance, in U.S. Pat. Nos. 5,075,012 and 5,248,416 a stream of unfiltered liquor which is approaching the dewatering apparatus and which contains flocculated solids is recycled to an earlier point in the feed line so as to promote flocculation of the feed.
When, as mentioned above, it is necessary to thicken the sludge by sedimentation or filtration prior to the final dewatering which forms a cake, the filtrate (or supernatant) from the thickener is sometimes not as clear as is desired. Instead of recycling all of this thickener filtrate or supernatant to the head of the plant, it is known to reuse the thickener supernatant or filtrate for diluting the polymeric flocculant which is added either to promote the thickening or to promote the subsequent dewatering.
In JP-A-57150480 it is proposed to hold effluent in a store tank and subject it to sedimentation in a sedimentation tank into which polymeric flocculant is added. Sludge is taken from the base of this tank and some of the supernatant from the tank is recycled to the store tank so as to dilute the liquor which is being passed to the sedimentation tank. It is alleged that the amount of flocculant which is needed in the sedimentation tank is reduced because of the increased dilution of the solids in that tank, but a disadvantage of this process is that the hydraulic load in the tank is increased.
In JP-A-58146498 sewage sludge, after aeration, is subjected to sedimentation in a sludge concentration tank in which sludge precipitates under gravity. The precipitated sludge is taken to a centrifugal thickener and the supernatant from the centrifugal thickener is combined with the supernatant from the sedimentation tank. The sludge from the centrifugal thickener is dosed with polymeric flocculant and is then subjected to dewatering to provide a cake and a filtrate. It seems that the amount of flocculant which is added is more than would normally be regarded as optimum as it is alleged that, due to the high dosage, large amounts of flocculant are lost with the filtrate and eutrophication is a significant problem in the resultant effluent.
Filtrate from the dewatering apparatus is recycled to the sludge entering the centrifugal thickener and/or to the sludge entering the sedimentation concentration tank and this is alleged to improve the sedimentation and/or thickening. However it should be noted that the only point at which flocculant is added is immediately prior to the dewatering apparatus and that the sedimentation concentration and the centrifugal thickening are both conducted without the deliberate addition of flocculant. Since these processes were being conducted without flocculant and since the filtrate is said to contain wasted flocculant, it is not surprising that adding some of this filtrate to the sludge which is to be subjected to sedimentation and/or centrifugal thickening in the absence of deliberately added flocculant would lead to an improvement in the sedimentation or thickening.
We are concerned with something entirely different, namely achieving a performance in a dewatering process which produces a cake and a reject liquor which is better than a performance which, prior to the invention, would have been regarded as already being optimum in that particular process. Thus, we are concerned inter alia with modifying a process which is already thought to be operating under optimum conditions (having regard to polymer dose, cake solids and reject liquor clarity) and obtaining improved cake solids and/or reject liquor clarity at constant polymer dose or obtaining constant cake solids and/or reject liquor clarity at reduced polymer dose. Clearly, none of the proposals discussed above gives any suggestion as to how to achieve this.
According to the invention, a sludge treatment process comprises
providing a sewage sludge,
mixing polymeric flocculant into the sludge at a dosing point, and then
substantially immediately subjecting the sludge to a dewatering process and thereby forming a cake and a reject liquor, and in this process
3 to 40% by volume of the reject liquor is recycled into the sludge at a dilution point substantially immediately before the dewatering process.
In normal operation of the process the dose of polymeric flocculant need be no more than the optimum dose of that flocculant for that sludge in that dewatering process without the recycling of the reject liquor.
A sludge treatment plant according to the invention comprises a dewatering apparatus by which sludge can be dewatered into a cake and a reject liquor, a sludge feed line for feeding sewage sludge into the apparatus, and a reject liquor line for leading reject liquor from the apparatus, and a recycling line for recycling reject liquor from the reject liquor line to the sludge feed line.
In this invention the reject liquor may be any type of reject liquor produced by a dewatering process. In particular it can be a supernatant, a filtrate or a centrate.
In a simple aspect of the invention a sludge dewatering process is conducted under substantially optimum conditions for that particular sludge and dewatering plant, i.e., at or slightly below optimum polymer dosage and substantially at optimum hydraulic loading rate and solids loading rate so as to obtain the substantially optimum combination of dewatered sludge solids and reject liquor clarity if there is no recycling of reject liquor, and 3 to 40% of the reject liquor is recycled to a dilution point substantially immediately before the dewatering process. As a result, the hydraulic load on the plant is increased (which would generally be thought to be undesirable) but it is found that the cake solids and/or clarity are improved if the dose of flocculant is maintained unchanged.
As a result, it is possible to modify the process by reducing the dose of flocculant and yet obtain cake solids and/or clarity equivalent to what was obtained at the higher dose without the recycling of the reject liquor. Depending upon the objective of the process, it is thus possible either to maximise cake solids and/or reject liquor clarity or to reduce the dose of flocculant, or to obtain a partial reduction in the dose of flocculant and a partial improvement in cake solids and/or reject liquor clarity. Thus, preferred processes for this invention are those where elimination of the recycle would result in reduced cake solids and/or requires additional polymer to maintain cake solids.
In many processes according to the invention, the dose of polymeric flocculant used in the process of the invention is below 95% and often below 90% and sometimes as little as 85 or 80% of the optimum dose under normal operation (i.e., without recycling of the reject liquor). Thus it is possible to achieve a saving in polymer which is easily 5% and can be as much as 15 or 20% while maintaining cake solids and/or reject liquor clarity.
It will be appreciated that the total amount of polymer which is being dosed into the process is generally no greater than, and is often less than, the amount that is required to give optimum bridging flocculation and dewatering in a process without the recycle and so the unexpected advantages in the process cannot be due to reliance on polymer which remains in the liquid phase and which is additional to what is required for optimum dewatering in the corresponding process conducted without recycle.
Further, the percentage reduction in polymer required to give constant cake solids and/or reject liquor clarity is often greater than the total amount of polymer which could, on any basis, be speculated to be present in the recycled reject liquor. For instance, if 10% of the reject liquor is recycled this represents a volume of liquid which would have carried 10% of the initial polymer dose into the dewatering process. Most or all of this initial 10% of the polymer dose would have been utilised in bridging flocculation and so would be trapped in the cake, and so the maximum amount of polymer which could be present in this 10% recycle is far less than 10% and possibly at or near zero, and yet it can typically lead to a reduction of 5 to 20% in the amount of polymer which has to be dosed into the sludge in order to obtain equivalent dewatering. Instead of reducing the amount of polymer, in some instances it can be beneficial to use a less costly and less efficient polymeric flocculant at increased, similar or reduced dosage.
The reason why improved dewatering performance is obtained, including being obtained at increased hydraulic loading rate, is unclear.
The invention also includes processes in which improved dewatering performance is obtained at constant hydraulic loading rate. Thus, in another simple process of the invention, an existing process wherein feed sludge is diluted with potable or clarified water prior to the dewatering process is modified by replacing some or all of this dilution water with recycled reject liquor. For instance there can be 50 to 100% replacement of the dilution water with the recycled reject liquor. The amount of recycled reject liquor (and any dilution water which is still used) is often the same as the original amount of dilution water but can be greater or less, so that the process then has an increased hydraulic load or a decreased hydraulic load when recycling in accordance with the invention. These processes are useful when the sludge naturally has a solids content and viscosity higher than is suitable for normal operation of the admixture of polymeric flocculant and the application of the subsequent dewatering process.
When the invention is applied to an existing process which is already operating with a polymer dose at or below optimum, the invention merely requires the addition of recycle of some of the reject liquor and possible reduction in the amount of polymer, or the use of less polymer or a less efficient (and perhaps less costly) polymeric flocculant. When a process is to be designed from the start in accordance with the invention, it is desirable to select the amount of polymeric flocculant so that it is not more than the optimum for the process without the recycle. In practice the plant operator will probably insist upon this anyway. The method of determining the optimum can be whatever is customary at that plant. It can be on the basis of actual operation of the plant and measurement of cake solids or clarity or a combination of both (depending upon the preference of the plant operator). It can be determined initially by a laboratory test which is known to be indicative of plant performance, for instance a CST test. Subsequent testing on plant of potential systems chosen in this way can establish the optimum type and dose of polymer.
In practice, the precise value of the optimum dose for that sludge in that dewatering process does not have to be determined to great accuracy but instead can be estimated in accordance with the normal accuracy associated with the operation of the plant. The dose used in the invention preferably does not substantially exceed this optimum, as otherwise the economic advantages of the process are reduced or lost, and preferably the dose is 70 to 100% of the optimum, often 80 to 95% of the optimum.
If no other test is established as being preferred at a particular plant, for the purposes of this specification the optimum is established beginning with systems chosen using minimum time as indicated from CST (capillary suction time) tests conducted over a range of doses. Final optimisation is carried out on the plant.
The optimum amount of recycle in any particular process will depend upon the sludge and the other process conditions but is generally at least 5% and usually is not more than 30%, by volume of the reject liquor. The recycling of 30% or higher does not appear to give any further improvement in performance but does give increased hydraulic loading rate, whereas the use of too little recycle does not give sufficient improvement. 7 to 25% is often a suitable range.
The process can be operated with a fixed amount of recycle, but preferably the amount of recycle is varied either to give a constant solids loading rate or to give a constant hydraulic loading rate or to give some predetermined combination of solids loading rate and hydraulic loading rate. Accordingly, the amount of recycle can be varied in response to the rate of supply of the sewage sludge and/or to the dry matter content of the sewage sludge. By this means it is possible not only to obtain the benefits of the invention but also the improved performance that comes from having a more uniform solids loading rate or hydraulic loading rate or both in the dewatering process. Preferably the dry matter content and/or the rate of flow of the sludge is monitored in-line continuously or intermittently and the monitored values are automatically utilised to adjust the amount of recycle, for instance using techniques broadly as described in PCT/GB96/00814.
A conventional sludge treatment plant has a sludge feed line which includes a sludge pump by which the sludge is pumped past the flocculant dosing point (which can in fact include two or more dosing points) and into the dewatering apparatus. The recycle can lead into any point substantially immediately before the dewatering process, i.e., substantially before the inlet to the dewatering apparatus. Accordingly it can be between the dosing point and the dewatering process (or between dosing points if there is more than one such point), between the sludge pump and the dosing point or before the sludge pump. If it is at the polymer dosing point, then the recycle can be used as part or all of the dilution water for the polymeric flocculant in which event the process may be operated without any increased hydraulic loading rate and may consist merely of the use of the recycle for polymer dilution instead of water from the drinking water supply or clarified water for polymer dilution. Preferably, however, the recycle is to a point before the dosing point. Preferably the recycle is to the suction side of the sludge pump, either direct into the pump or into the sludge line ahead of but close to the pump.
The recycle point (and the polymer dosing point) must both be substantially immediately before the inlet to the dewatering plant since it is well known that the benefits of adding treatment chemicals to a material which is to be dewatered are generally lost if the addition of the treatment chemical is conducted too long before the start of the dewatering process. Thus the point at which the recycle is added to the sludge feed and the point at which the polymer is added to the sludge feed are generally both such that the sludge enters the dewatering apparatus within a few seconds or, at the most, a few minutes after the addition. Typically therefore the recycle and the addition of the polymer are both conducted at a time which is less than 10 minutes and usually less than 5 minutes and most preferably less than 2 minutes before the time when the sludge enters the dewatering apparatus.
The method of recycle should be conducted in such a manner that the amount of recycle can easily be controlled accurately and such that it is substantially unaffected by back pressure from the sludge line into the recycling line. This difficulty is minimised when, as is preferred, the recycle is to the suction side of the sludge pump but if the recycle is to the sludge line between the pump and the dewatering apparatus it may be necessary to install an arrangement which will ensure that the desired controlled amount of recycle into the sludge can be introduced against the prevailing pressure.
The dewatering apparatus can be any suitable apparatus by which sewage sludge can be dewatered to form a cake and a reject liquor. Thus it can be a dewatering centrifuge of the type which will produce a cake and a centrate, for instance a KHD Humboldt or Alfa Laval Sharples (trade names) centrifuge. Alternatively it can be a belt press or a plate and frame press. Novel apparatus according to the invention comprises any such dewatering apparatus (equipped with its conventional inlet feed line and outlet reject liquor line) wherein means for recycling a controlled proportion of reject liquor are provided leading from the outlet reject liquor line to the inlet feed line. This means may comprise suitable valving and flow meters and other control means for diverting a controlled proportion of the reject liquor back into the inlet in response either to manual operation or to automated operation, for instance automated in response to measurement of the rate of flow or the solids content, or both, of the sludge approaching the dewatering apparatus.
The sludge can be any conventional type of sewage sludge and is frequently a blend of primary and secondary sludges. The sludge which is fed to the dewatering process usually has a solids content above 0.5 or 1% by weight and usually above 2 or 3%. Generally it is not more than about 5 or 6% but in some instances it can be as much as 8% or even 10%, depending upon the nature of the sludge.
If the sludge, as initially supplied from the primary and/or secondary stages, does not have appropriate solids content then the solids content may be adjusted before approaching the dewatering process of the invention. This adjustment may be by dilution or by thickening. The thickening can be assisted by the use of a polymeric flocculant. The thickening results in the formation of a filtrate or supernatant (which is usually recycled to the head of the plant) and the thickened sludge which is then used in the invention. The thickening can be by, for instance, sedimentation, gravity filtration or centrifuging and results in the production of a thickened sludge (in contrast to the dewatering process of the invention which produces a cake).
The polymeric flocculant can be a single polymer added at one or more dosage points or it can be different polymers, generally added sequentially. It may be used in combination with an inorganic coagulant, in known manner. Usually part or all of the polymeric flocculant is a water soluble synthetic polymer usually formed from a water soluble ethylenically unsaturated monomer or monomer blend. It may be anionic, non-ionic or cationic. Often the flocculant is formed from a blend of non-ionic monomer (such as acrylamide) and cationic monomer, such as dialkylaminoalkyl (meth)-acrylate or -acrylamide or diallyl dimethyl ammonium chloride). However any of the other conventional cationic or anionic or non-ionic sludge flocculants can be used in the invention. The molecular weight of synthetic polymers used as flocculant is usually high, for instance indicated by an intrinsic viscosity (suspended level viscometer at 20xc2x0 C. in 1N sodium chloride solution buffered to pH7) above 4 and often 6 to 30 dl/g, usually 6 to 15 dl/g when the polymer is cationic and 10 to 30 dl/g when it is non-ionic or anionic.
The polymer is usually provided initially to the plant as powder or reverse phase emulsion (which can be anhydrous) and is usually activated in water before addition to the sludge, all in conventional manner. As indicated above, some or all of the water used for the activation can be part or all of the reject liquor recycle.
The invention also provides, in a second aspect, an improved thickening process for sewage sludge comprising
providing a sewage sludge,
mixing polymeric flocculant into the sludge at a dosing point and then
substantially immediately subjecting the sludge to a thickening process and thereby forming a thickened sludge and a reject liquor, wherein
30 to 40% by volume of the reject liquor is recycled directly into the sludge at a dilution point substantially immediately before the dewatering process and before the flocculant dosing point.
In this aspect of the invention improvements are found in thickening processes by using a principle similar to that of the first aspect of the invention for dewatering. All process features of the dewatering process of the invention may be applied to the thickening process of the invention where relevant.
The invention also provides, in a third aspect, a process for improved dewatering of a cellulosic sludge comprising
providing a cellulosic sludge,
mixing polymeric flocculant into the sludge at a dosing point and then
substantially immediately subjecting the sludge to a dewatering process and thereby forming a cake and a reject liquor, wherein
3 to 40% by volume of the reject liquor is recycled into the sludge at a dilution point substantially immediately before the dewatering process.
In this aspect of the invention the cellulosic sludge can be for instance paper mill effluent sludge or de-inking plant sludge.
All process features of the dewatering process of the first aspect of the invention may be applied to the dewatering process of the third aspect of the invention where relevant.

Ciba Specialty Chemcials Water Treatments Ltd.


A method of positioning a product on a display. The method including the steps of defining an indicia row associated with the display, defining an indicia column associated with the display, providing a product coordinates set specifying an intended position of the product on the display, and locating the product on the display using the positioning coordinates set at a location corresponding to the product coordinates set.

The present invention relates to a device for setting product planograms in a retail store or the like.
Retail stores such as a department store have a limited amount of space in which to display products or present them for sale. Many products are presented for sale by hanging them on display support members such as display hooks, pegs, arms and the like that are affixed to a perforated board or pegboard containing a plurality of apertures. The display support members are capable of being securely mounted within the apertures and can support salable goods in selected positions on the board for display purposes. The apertures are arranged on the perforated board in a plurality of rows and columns. It is advantageous to arrange the various display support members to maximize the space wherein products are presented for sale. Arranging the salable products on a perforated board in a neat and orderly fashion wherein space is maximized is a time-consuming process that requires skill and merchandising knowledge. A chain of stores can save time and money by having a merchandising expert at a central location determine the layout for a planogram, and then send the coordinates to the individual stores, thereby allowing employees at the separate stores to place the salable products.
There are prior art devices for arranging display support members on perforated boards. For example, U.S. Pat. No. 4,788,784 to Templin discloses a removable adhesive display sheet which, when mounted onto a perforated board, provides a display system for arranging and displaying salable goods to customers. The sheet includes apertures that align with the apertures in the board when the sheet is adhered to the board. The sheet includes display indicia, such as descriptive indicia or pictorial indicia, thereon. However, this system has many drawbacks. When adhering the sheet to the perforated board it is difficult to align the apertures. Also, it is time consuming to manufacture the sheet with the display indicia thereon. Furthermore, the pictorial indicia must be specific to certain salable items.
A long felt need exists for a system for arranging salable items and the corresponding display support members on a perforated board that is simple and overcomes the drawbacks of the prior art.
In accordance with one aspect of the present invention there is provided a method for positioning a product on a display. The method includes the steps of defining an indicia row associated with the display, defining an indicia column associated with the display, providing a product coordinates set specifying an intended position of the product on the display, and locating the product on the display using the positioning coordinates set at a location corresponding to the product coordinates set. A column indicia and a row indicia form a set of coordinates. In a preferred embodiment, the method includes the additional step of sliding the indicia column relative to the indicia row.
In accordance with another aspect of the present invention there is provided a system for facilitating the positioning of at least one product on a display. The system includes a coordinate indicia row associated with the display, and a coordinate indicia column associated with the display. The coordinate indicia row and the coordinate indicia column cooperate to define at least one product coordinates set at a point on the display where the product is to be positioned. In a preferred embodiment of the invention, the display is a perforated board, and the indicia column is slidable relative to the indicia row.
In accordance with yet another aspect of the present invention there is provided a device for facilitating the positioning of a product on a display. The device includes a first horizontal member adapted to removably engage the display, said horizontal member including coordinate indicia thereon, and a coordinate member associated with the horizontal member. A coordinate from the first horizontal member and a coordinate from the coordinate member form a product coordinates set for facilitating positioning of a product on the display. In a preferred embodiment of the present invention the display is a perforated board and the coordinate member is a tape measure. In another preferred embodiment of the invention the device includes a carriage that is slidable relative to the first horizontal member.
In accordance with yet another aspect of the present invention there is provided a merchandising device comprising a coordinate system that includes first and second coordinate sets. The first coordinate set includes a plurality of alphabetical, numeric or alphanumeric elements that progress alphabetically, numerically or alphanumerically in a first direction and the second coordinate set includes substantially the same elements as the first coordinate set. The elements of the second coordinate set progress in a second direction that is substantially opposite to the first direction.
Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.


The heat-sink assembly of the invention is attached to the PC board with the use of surface mount technology. The assembly comprises a base part or a base member soldered to the PC board and a top part or a heat-sink member snapped-on through the central opening of the base member by irreversibly deforming bendable lugs which may have a radial or any other suitable shape. The bottom of the heat-sink member may be pushed down to physical contact with the top of the chip or to a position that leaves a space between the bottom of the heat-sink member and the top of the chip, so that the aforementioned space may be filled with a heat-conducting medium. It is an option to use the base part only. If necessary, a second heat-sink member of the same type, which could have different dimensions, can be soldered to the PC board side opposite to the chip. The heat sinks could be used with or without a fan. In the case of the assembly with a fan, the deice may have an air-flow guiding funnel formed on side portion of the base member.

The present invention relates to heat a sink for removal of heat from a heat source, in particular, from a semiconductor chip or a similar electronic or electric devices which are heated during the operation and are located in confined spaces.
Semi-conductor chip packages, which may contain a plurality of integrated circuits combined into a compact unit, become more complex and operate at higher frequencies. As a result, during operation they generate more heat. As a rule such devices are located In confined spaces from which the heat has to be removed. However, electronic devices can normally be heated to a predetermined limit. Heating above this limit may impair performance characteristics of the device and even lead to its damage. Moreover, long-term operation in a heated state, even at temperatures below the threshold, may drastically reduce the service life of the device.
Thus, in general, the component package configuration and construction are specifically designed to allow for maximized heat dissipation. Heat spreaders and heat sinks are employed in such electronic component packages to transfer heat to a moving air stream or on to another surface.
It should also be noted that a part of the heat flows from the chip to the ground plane of the PC board through the pins and the bottom side of the case, and will be partly carried away by convection to the entire PC board. As result, the temperature of the PC board increases for the following four reasons: 1) the PC board thin copper ground plane has high heat resistance; 2) the available ground plane size of copper is limited in dense PC boards; 3) the narrow and thin traces have high heat resistance; 4) other devices on same board might generate heat too, which can heat the device to higher temperatures.
In some IC devices, small part of the heat will be dissipated to the top side of the IC, as the heat resistance between the internal die and the top case Is fairly large. In this case the base part will be the dominant one for heat dissipation.
In order to enhance the heat-dissipation effect through a heat sink, some heat sinks are provided with an air funnel for directing the flow of air through the heat sink and between the heat-dissipating fins.
In modem heat-sink assemblies, the problems associated with limitations in connection with holes in the chip support members are solved with the so-called surface-mount technique, while the problems associated with automatic assembling are solved by the use of various snapping connections.
The surface-mount technique is based on the use of soldering. Pads on the circuit board are provided with a solder mount for the heat sink or a clip holding the heat sink. A circuit component is mounted to the heat sink and the component and heat sink are mounted to the board, the heat sink being mounted to the pads to dissipate heat from the circuit component attached thereto. In some cases, the heat sink or pads are connected to a ground plane in the circuit board to additionally dissipate heat from the circuit board. Heat-exchanging contact between the heat sink and the chip can be carried out through mechanical contact or through a heat-conductive medium that fills the space between the bottom of the heat sink and the facing surface of the chip. Furthermore, the heat is dissipated from all heated surfaces through a natural convection.
An example of a heat-sink assembly based on the use of a surface mounting technique is a device described in U.S. Pat. No. 4,625,260 issued in 1986 to W. Jordan, et al. The device comprises a heat-sink support, which is soldered to a PC board and has spring-loaded clips for detachably securing a heat sink. Although this device is suitable for automatic assembling in combination with the surface-mount technique, it has spring-loaded attachment of the heat sink, which is unreliable for use under conditions of shakes and vibrations.
Heat-sink devices are not necessarily surface mounted. For example, U.S. Pat. No. 5,386,144 issued in 1995 to P. Variot et al. discloses an electronic component assembly which comprises an electronic component package, a heat sink having an outwardly projecting latching members, and spring arms on the component package for resiliently clamping the latching members to the component package. The heat sink has a body configured and arranged to bear on the electronic component and mounts a latching member extending from the body and including a shank extending from the heat sink body having a latching flange at the distal end of the shank. A disadvantage of the invention disclosed in U.S. Pat. No. 5,386,144 is that it is applicable to component packages having a very specific configuration and therefore is not universal in its use. Another disadvantage is a complicated construction of the heat-sink attachment that requires the use of springing and latching members.
U.S. Pat. No. 6,075,699 issued in 2000 to W. Rife discloses a heat sink assembly installed above an electronic component for removing heat therefrom. The assembly includes a base member with downwardly directed legs, which have snapping ends for insertion into mounting holes formed on a support that mounts the electronic component. The base member has a central threaded opening for threadably receiving a heat sink to position in which the end of the heat sink is in flush thermal communication with the electronic component while the legs are secured within their respective holes in the electronic component. The device of U.S. Pat. No. 6,075,699 is designed for removal of heat only from the chip itself and cannot be used for cooling the surrounding lead wires and other electrical connections. This is because the heat is transferred to the heat exchanger only from the chip and cannot be efficiently transferred through the snapping ends of the attachment legs. Another serious disadvantage of the aforementioned construction is that it has a limited application and is suitable only to those designs, which allow holes in a chip-supporting member, which is not always the possible. Furthermore, in case of automatic assembling, threaded connection of the heat sink with the base member will slow down the assembling operation and will make it more complicated and expensive.
An example of a heat-sink assembly which can be used only with PC boards that allow holes in their structures is a device of U.S. Pat. No. 5,917,701 issued in 1999 to T. Solberg, which discloses a vertically-arranged heat-sink support structure that consists of a lower member and an upper member. The circuit board has a plurality of openings in a mounting surface thereof. The fastener includes a body having a main portion. A spring clip extends in a first direction from the main portion into the groove and is biased to engage the first and second surfaces of the heat sink. A plurality of latches on the spring clip engages the lock recesses when the spring clip engages the first and second surfaces of the heat sink. A plurality of anchor lugs extends in a second direction from the main portion, opposite the first direction, to be received in respective openings in the board to rigidly attach the fastener to the circuit board. Preferably, the anchor lugs are of differing lengths and configurations to permit assembly of the clip to differently sized circuit boards. Also preferably, engagement protrusions on the clip engage a concave surface on the heat sink.
An advantage of the assembly of U.S. Pat. No. 5,917,701 is that it is suitable for automatic assembling. However, this assembly requires a provision of holes in the PC board. A second disadvantage is a provision of spring-loaded clips, since with the lapse of time the clips may loose their resiliency, so that conditions of heat-conducting contact can be lost. Moreover, if the entire device operates under conditions of vibrations or shocks, the upper and lower parts of the heat-sink attachment can get loose and be completely disconnected.
It is an object of the present invention to provide a heat sink device which is suitable for automatic assembling, is simple and universal in construction, inexpensive to manufacture, does not use screws, ridge other threaded connections, or clips, removes heat not only from the chip but from the chip-supporting areas of the PC board, can be installed on a PC board without the use of holes in the PC board, allows to minimize the amount of parts in a heat-sink assembly by combining the base and the funnel into an integral unit made from a single workpiece, simplifies attachment of the heat sink to the base with the use of an automatic assembly machine such as a xe2x80x9cpick and placexe2x80x9d machine, and improves reliability of heat-transfer contacts in a heat-transfer chain of the assembly.
The heat-sink assembly of the invention is attached to the PC board with the use of surface mount technology. The assembly comprises a base part or a base member soldered to the PC board and a top part or a heat-sink member snapped-on through the central opening of the base member by irreversibly deforming bendable lugs which may have a radial or any other suitable shape. The bottom of the heat-sink member may be pushed down to physical contact with the top of the chip or to a position that leaves a space between the bottom of the heat-sink member and the top of the chip, so that the aforementioned space may be filled with a heat-conducting medium. It is an option to use the base part only. If necessary, a second heat-sink member of the same type, which could have different dimensions, can be soldered to the PC board side opposite to the chip. The heat sinks could be used with or without a fan.


This invention relates to a blue colored liquid crystal composition comprising an ethoxylated nonionic surfactant, an ethoxylated alkyl ether sulfate surfactant, a sulfonate surfactant, a magnesium inorganic salt, an abrasive, a blue colorant and water.

This invention relates to a blue colored liquid crystal detergent composition. More specifically, it is of a blue colored liquid detergent composition in a liquid crystal state which when brought into contact with tough difficult to clean soils is superior to other liquid detergent compositions in detergency and in other physical properties as well as provides a sharp contrast to the surface being cleaned thereby making it easier to see the endpoint when rinsing the product from the surface being cleaned.
Liquid aqueous synthetic organic detergent compositions have long been employed for human hair shampoos and as dishwashing detergents for hand washing of dishes (as distinguished from automatic dishwashing machine washing of dishes). Liquid detergent compositions have also been employed as hard surface cleaners, as in pine oil liquids, for cleaning floors and walls. More recently they have proven successful as laundry detergents too, apparently because they are convenient to use, are instantly soluble in wash water, and may be employed in xe2x80x9cpre-spottingxe2x80x9d applications to facilitate removal of soils and stains from laundry upon subsequent washing. Liquid detergent compositions have comprised anionic, cationic and nonionic surface active agents, builders and adjuvants, including, as adjuvants, lipophilic materials which can act as solvents for lipophilic soils and stains. The various liquid aqueous synthetic organic detergent compositions mentioned serve to emulsify lipophilic materials, including oily soils, in aqueous media, such as wash water, by forming micellar dispersions and emulsions. They also serve to disperse and suspend particulate soils.
Although emulsification is a mechanism of soil removal, it has been only comparatively recently that it was discovered how to make microemulsions which are much more effective than ordinary emulsions in removing lipophilic materials from substrates. Such microemulsions are described in British Patent Specification No. 2,190,681 and in U.S. Pat. Nos. 5,075,026; 5,076,954 and 5,082,584 and 5,108,643, most of which relate to acidic microemulsions useful for cleaning hard surfaced items, such as bathtubs and sinks which microemulsions are especially effective in removing soap scum and lime scale from them. However, as in Ser. No. 4,919,839 the microemulsions may be essentially neutral and such are also taught to be effective for microemulsifying lipophilic soils from substrates. In U.S. patent application Ser. No. 7/313,664 there is described a light duty microemulsion liquid detergent composition which is useful for washing dishes and removing greasy deposits from them in both neat and diluted forms. Such compositions include complexes of anionic and cationic detergents as surface active components of the microemulsions.
The various microemulsions referred to include a lipophile, which may be a hydrocarbon, a surfactant, which may be an anionic and/or a nonionic detergent(s), a co-surfactant, which may be a poly-lower alkylene glycol lower alkyl ether, e.g., tripropylene glycol monomethyl ether, and water.
Although the manufacture and use of detergent compositions in microemulsion form significantly improve cleaning power and greasy soil removal, compared to the usual emulsions, the present invention improves them still further and also increases the capacity of the detergent compositions to adhere to surfaces to which they have been applied. Thus, they drop or run substantially less than cleaning compositions of xe2x80x9csimilarxe2x80x9d cleaning power which are in microemulsion or normal liquid detergent form. Also, because they form microemulsions with lipophilic soil or stain material spontaneously, with essentially no requirement for addition of any energy, either thermal or mechanical, they are more effective cleaners at room temperature and at higher and lower temperatures that are normally employed in cleaning operations than are ordinary liquid detergents, and are also more effective than detergent compositions in microemulsion form.
U.S. Pat. No. 5,035,826 teaches liquid crystal compositions but these compositions exhibit thermal stability in the limited temperature range of 19xc2x0 C. to 36xc2x0 C.
The present invention provides an improved, blue colored liquid crystal detergent composition having lower interfacial tension which improves cleaning hard surface in the form of a liquid crystal which is suitable for cleaning hard surfaces such as plastic, vitreous and metal surfaces having a shiny finish, oil stained floors, automotive engines and other engines. More particularly, the improved cleaning compositions exhibit good grease soil removal properties due to the lower interfacial tension and suspended abrasives. These new compositions leave the cleaned surfaces shiny without the need of or requiring only minimal scrubbing without additional rinsing or wiping. The latter characteristic is evidenced by little or no visible residues on the unrinsed cleaned surfaces and, accordingly, overcomes one of the disadvantages of prior art products.
The blue color of the liquid crystal detergent composition has a sharp contrast with the target surface being cleaned. Therefore, it is easier to see the end point when rinsing the liquid crystal detergent composition from the surface being cleaned.
Surprisingly, these desirable results are accomplished even in the absence of polyphosphate or other inorganic or organic detergent builder salts and also in the complete absence or substantially complete absence of grease-removal solvent.
In one aspect, the invention generally provides a stable, liquid crystal, cleaning composition especially effective in the removal of oily and stuck-on food from dishware. The blue colored liquid crystal composition includes, on a weight basis:
(a) 0.5% to 6% of an ethoxylated alkyl ether surfactant;
(b) 10% to 24% of a sodium salt of a C8-C16 linear alkyl benzene sulfonate surfactant;
(c) 1% to 10% of at least one ethoxylated nonionic surfactant;
(d) 0.5% to 6%, more preferably 0.5% to 5% of a magnesium, sodium, calcium or potassium salt such as magnesium sulfate heptahydrate and/or magnesium chloride.
(e) 10% to 22% of an abrasive such as a calcium carbonate; and
(f) 0.005% to 0.1%, more preferably 0.01% to 0.06% of a blue colorant; and
(g) the balance being water, wherein the composition does not contain a zwitterionic surfactant or a cosurfactant such as glycerol, ethylene glycol, water-soluble polyethylene glycols having a molecular weight of 300 to 1000, polypropylene glycol of the formula HO(CH3CHCH2O)nH wherein n is a number from 2 to 18, mixtures of polyethylene glycol and polypropyl glycol (Synalox) and mono C1-C6 alkyl ethers and esters of ethylene glycol and propylene glycol having the structural formulas R(X)nOH and R1(X)nOH wherein R is C1-C6 alkyl group, R1 is C2-C4 acyl group, X is (OCH2CH2) or (OCH2(CH3)CH) and n is a number from 1 to 4, diethylene glycol, triethylene glycol, an alkyl lactate, wherein the alkyl group has 1 to 6 carbon atoms, 1methoxy-2-propanol, 1methoxy-3-propanol, and 1methoxy 2-, 3- or 4-butanol and the liquid crystal composition has a storage modulus equal to or higher than one Pascal (1 Newton/sq. m.), more preferably higher than 30 Pascal at a temperature of 20xc2x0 C. to 40xc2x0 C. at a strain of 0.1% to 5% and a frequency of 10 radians/second as measured on a Carri-Med CSL2 500 Rheometer and is thermally stable and exists as a liquid crystal in the temperature range from 8xc2x0 C. to 43xc2x0 C., more preferably 4xc2x0 C. to 43xc2x0 C.
The present invention relates to a stable blue colored liquid crystal detergent composition comprising approximately by weight: 0.5% to 6% of an ethoxylated C8-C18 alkyl ether sulfate, 1% to 10% of an ethoxylated nonionic surfactant, 10% to 24% of a sodium salt of a C8-C16 linear alkyl benzene sulfonate surfactant, 0.5% to 6%, more preferably 0.5% to 5% of a magnesium, sodium, calcium or potassium salt, 10% to 22% of an abrasive such as a calcium carbonate, 0.005% to 0.1%, more preferably 0.01% to 0.06% of a blue colorant and the balance being water, wherein the composition does not contain a zwitterionic surfactant or a cosurfactant such as glycerol, ethylene glycol, water-soluble polyethylene glycols having a molecular weight of 300 to 1000, polypropylene glycol of the formula HO(CH3CHCH2O)nH wherein n is a number from 2 to 18, mixtures of polyethylene glycol and polypropyl glycol (Synalox) and mono C1-C6 alkyl ethers and esters of ethylene glycol and propylene glycol having the structural formulas R(X)nOH and R1(X)nOH wherein R is C1-C6 alkyl group, R1 is C2-C4 acyl group, X is (OCH2CH2) or (OCH2(CH3)CH) and n is a number from 1 to 4, diethylene glycol, triethylene glycol, an alkyl lactate, wherein the alkyl group has 1 to 6 carbon atoms, 1methoxy-2-propanol, 1methoxy-3-propanol, and 1methoxy 2-, 3- or 4-butanol and the liquid detergent composition has a storage modulus equal to or higher than one Pascal (1 Newton/sq. m.), more preferably higher than 10 Pascal at a temperature of 20xc2x0 C. to 40xc2x0 C. at a strain of 0.1% to 5% second as measured on a Carri-Med CSL2 500 Rheometer and is thermally stable and exists as a liquid crystal in the temperature range from 8xc2x0 C. to 43xc2x0 C., more preferably 4xc2x0 C. to 43xc2x0 C.
The blue colored liquid crystal detergent composition has an L* value of about 41.67 to about 42.67, an a* value of about xe2x88x925.13 to about xe2x88x925.53, a b* values of about xe2x88x928.98 to about xe2x88x929.58, a C* value of about 10.20 to about 11.20 and a h* value of about 238.13 to about 242.13 under a light source of Daylight D65/10.
The nonionic surfactant is present in amounts of about 1% to 10%, preferably 2% to 8% by weight of the liquid crystal composition and provides superior performance in the removal of oily soil and mildness to human skin.
The ethoxylated nonionic surfactants utilized in this invention are commercially well known and include the primary aliphatic alcohol ethoxylates and secondary aliphatic alcohol ethoxylates. The nonionic synthetic organic surfactants generally are the condensation products of an organic aliphatic or alkyl aromatic hydrophobic compound and hydrophilic ethylene oxide groups. The length of the polyethenoxy chain can be adjusted to achieve the desired balance between the hydrophobic and hydrophilic elements.
The nonionic surfactant class includes the condensation products of a higher alcohol (e.g., an alkanol containing about 8 to 16 carbon atoms in a straight or branched chain configuration) condensed with about 2.5 to 20 moles of ethylene oxide, for example, lauryl or myristyl alcohol condensed with about 16 moles of ethylene oxide (EO), tridecanol condensed with about 6 moles of EO, myristyl alcohol condensed with about 10 moles of EO per mole of myristyl alcohol, the condensation product of EO with a cut of coconut fatty alcohol containing a mixture of fatty alcohols with alkyl chains varying from 10 to about 14 carbon atoms in length and wherein the condensate contains either about 6 moles of EO per mole of total alcohol or about 9 moles of EO per mole of alcohol and tallow alcohol ethoxylates containing 6 EO to 11 EO per mole of alcohol.
A preferred group of the foregoing nonionic surfactants are the Neodol ethoxylates (Shell Co.), which are higher aliphatic, primary alcohol containing about 9-15 carbon atoms, such as C9-C11 alkanol condensed with 2.5 to 10 moles of ethylene oxide (Neodol 91-8 or Neodol 91-5), C12-13 alkanol condensed with 3 moles ethylene oxide (Neodol 23-3), C12-15 alkanol condensed with 12 moles ethylene oxide (Neodol 25-12), C14-15 alkanol condensed with 13 moles ethylene oxide (Neodol 45-13), and the like. Such ethoxamers have an HLB (hydrophobic lipophilic balance) value of about 7 to 9 and give good O/W emulsification, whereas ethoxamers with HLB values below 7 contain less than 4 ethyleneoxide groups and tend to be poor emulsifiers and poor detergents.
Additional satisfactory water soluble alcohol ethylene oxide condensates are the condensation products of a secondary aliphatic alcohol containing 8 to 18 carbon atoms in a straight or branched chain configuration condensed with 5 to 30 moles of ethylene oxide. Examples of commercially available nonionic detergents of the foregoing type are C11-C15 secondary alkanol condensed with either 9 EO (Tergitol 15-S-9) or 12 EO (Tergitol 15-S-12) marketed by Dow and Union Carbide.
The ethoxylated alkyl ether sulfate, surfactants which may be used in the composition of this invention are water soluble such as triethanolamine and include the sodium, potassium, ammonium and ethanolammonium salts of an C8-18 ethoxylated alkyl ether sulfate surfactants have the structure:
xe2x80x83Rxe2x80x94(OCHCH2)nOSOxe2x88x923M+
wherein n is about 0 to about 5 and R is an alkyl group having about 8 to about 18 carbon atoms, more preferably 12 to 15 and natural cuts, for example, C12-14; C12-15and M is an ammonium cation or a metal cation, most preferably sodium. The ethoxylated alkyl ether sulfate is present in the composition at a concentration of about 0.5% to about 6% by weight, more preferably about 1% to 5% by weight.
The ethoxylated alkyl ether sulfate may be made by sulfating the condensation product of ethylene oxide and C8-10 alkanol, and neutralizing the resultant product. The ethoxylated alkyl ether sulfates differ from one another in the number of carbon atoms in the alcohols and in the number of moles of ethylene oxide reacted with one mole of such alcohol. Preferred ethoxylated alkyl ether polyethenoxy sulfates contain 12 to 15 carbon atoms in the alcohols and in the alkyl groups thereof, e.g., sodium myristyl (3 EO) sulfate.
Ethoxylated C8-18 alkylphenyl ether sulfates containing from 2 to 6 moles of ethylene oxide in the molecule are also suitable for use in the invention compositions. These detergents can be prepared by reacting an alkyl phenol with 2 to 6 moles of ethylene oxide and sulfating and neutralizing the resultant ethoxylated alkylphenol. The concentration of the ethoxylated alkyl ether sulfate surfactant is about 1 to about 8 wt. %.
The sulfonated anionic surfactant used in the instant composition is the well known higher alkyl mononuclear aromatic sulfonates, such as the higher alkylbenzene sulfonates containing 8 to 18 or preferably 8 to 16 carbon atoms in the higher alkyl group in a straight or branched chain, or C8-C15 alkyl toluene sulfonates. A preferred alkylbenzene sulfonate is a sodium salt of linear alkylbenzene sulfonate having a higher content of 3-phenyl (or higher) isomers and a correspondingly lower content (well below 50%) of 2-phenyl (or lower) isomers, such as those sulfonates wherein the benzene ring is attached mostly at the 3 or higher (for example 4, 5, 6 or 7) position of the alkyl group and the content of the isomers in which the benzene ring is attached in the 2 or 1 position is correspondingly low. Preferred materials are set forth in U.S. Pat. No. 3,320,174, especially those in which the alkyls are of 10 to 13 carbon atoms.
The abrasive which is used at a concentration of 10 wt. % to 22 wt. %, more preferably 12 wt. % to 20 wt. % is selected from the group consisting of polyethylene powders, calcium carbonate and silica and mixtures thereof. A preferred calcium carbonate is Calcite Q100 manufactured by Huber Engineered Materials. A preferred silica is White Silexxe2x80x94120 grade by U.S. Silica. Another preferred silica is Tixosil 103 manufactured by Rhodia.
The blue colorant used in the instant composition is selected from the group consisting of Acid Blue 1 (Cas No. 129-17-9), Acid Blue 3 (Cas No. 3536-49-0), Acid Blue 5 (Cas No. 3374-30-9), Acid Blue 7, (Cas No. 3486-30-4), Acid Blue 9 (Cas Nos. 2650-18-2,; 37307-56-5 and 6371-85-3) Solvent Blue 63 (Cas No. 64553-79-3), Acid Blue 80 (Cas. No. 4474-24-2), Acid Blue 62 (Cas. No. 4368-56-3), Vat Blue 4 (Cas. No. 81-77-6), Vat blue 6/Pigment 64 (Cas. No. 130-20-1), Vat Blue 1/Pigment Blue 66 (Cas. No. 482-89-3), Acid Blue 74/food blue 1, Pigment Blue 63 (Cas. No. 860-22-0), Pigment Blue 16 (Cas. No. 574-93-6), Pigment Blue 15 (Cas. No. 147-14-8), Direct Blue 86 (Cas. No. 1330-38-7), Pigment Blue 29 (Cas. Nos. 1317-97-1 and 57455-37-5), pigment Blue 27 (Cas. No. 14038-43-8), Guaizulene (Cas. No. 489-84-9), Bimothymol Blue (Cas. No. 76-59-5) and especially, liquitint blues manufactured by Milliken Chemical which is reactive blue dye such as Cl reactive Blue 5, Cl reactive Blue 2, Cl reactive Blue 4, Cl reactive Blue 7, Cl reactive Blue 15, Cl reactive Blue 19 or Cl reactive Blue 27 react through an electrophilic reactive group bonded to the reactive dye with a nucleophilic linking group which is attached to a poly (oxyalkylene)-containing moiety.
The instant composition contains 0.5 to about 6 wt. %, more preferably about 0.5 to about 5 wt. % of a magnesium, sodium, calcium or potassium salt such as magnesium sulfate and mixtures thereof.
The final essential ingredient in the inventive liquid crystal compositions having improved interfacial tension properties is water. The proportion of water in the liquid crystal detergent composition generally is in the range of 20% to 97%, preferably 70% to 97% by weight.
The instant composition can also contain 0 to 1.0%, more preferably 0.01% to 0.25% by weight of a pigment or dye and 0 to 1%, more preferably 0.01% to 0.5% of a fragrance.
A composition of this invention is in a liquid crystal state when it is of lypotropic structure, is opaque blue, and has a storage modulus equal to or higher than one Pascal (1 Newton/sq. m.), more preferably higher than 10 Pascal and most preferably higher than 20 Pascal and when measured at a temperature of 20 to 40xc2x0 C., at a frequency of ten radians per second and at a strain of 0.1 to 5% and a frequency of 10 radians/second. The rheological behavior of the compositions of this invention were measured at 25xc2x0 C. by means of a Carri-Med CSL2 500 Rheometer. In making the measurement, a cone and plate are used at a cone angle of 4 degrees with a cone diameter of 4 cm, measurement system gap of 119.0 micro meters and a measurement system inertia of 1.226 micro Nm secxe2x88x922.
To make the liquid crystal compositions of the invention is relatively simple because they tend to form spontaneously with little need for the addition of energy to promote transformation to the liquid crystal state. However, to promote uniformity of the composition mixing will normally be undertaken and it has been found desirable first to mix the abrasive, color and anionic surfactants with the water, followed by the salt and then the nonionic surfactant is mixed with the fragrance. It is not necessary to employ heat and most mixings are preferably carried out at about room temperature (20-25xc2x0 C.).
The invented compositions may be applied to such surfaces by pouring onto them, by application with a cloth or sponge, or by various other contacting means. Such application may be onto hard surfaces, such as dishes, pots, pans, counter tops, or range tops, from which lipophilic stuck on, greasy or oily soil is to be removed, or may be onto fabrics, such as laundry, which has previously been stained with lipophilic soils, such as motor oil. The invented compositions may be used as detergents and as such may be employed in the same manner in which liquid detergents are normally utilized in dishwashing, floor and wall cleaning and laundering, but it is preferred that they be employed as pre-spotting agents too, in which applications they are found to be extremely useful in loosening the adhesions of lipophilic stuck on soils to substrates.
The various advantages of the invention have already been set forth in some detail and will not be repeated here. However, it will be reiterated that the invention relates to the important discovery that effective liquid detergent compositions can be made in the liquid crystal state and that because they are in such state they are especially effective at suspending solid abrasive and thus removing lipophilic soils from substrates and also are effective in removing from substrates non-lipophilic materials. Such desirable properties of the liquid crystal detergent compositions of this invention make them ideal for use as pre-spotting agents and detergents for removing hard-to-remove soils from substrates in various hard and soft surface cleaning operations.

Blue colored liquid crystal compositions


The present invention provides for the treatment of an individual suffering from lupus erythematosus utilizing a serine protease inhibitor. The treatment includes the use of a corticosteroid that is administered separately or in combination. The serine proteases preferred are alpha 1-antitrypsin, secretory leucocyte protease inhibitor, alpha 2-macroglobulin or mixtures thereof.

The present invention relates to the treatment of lupus erythematosus. More specifically, there is provided the treatment of inflammatory conditions, rashes or lesions which occur with patients with systemic lupus erythematosus (SLE) by the administration of protease inhibitors.
The common treatment for lupus erythematosus involves the H use of several drugs as well as sunscreens. Hydroxychloroquine alone or in combinations with oral steroids is used. Topical steroids and/or vitamin A are also used for treating skin eruptions. The patients with severe SLE involving several organs have been treated with immunosuppressive agents (corticosteroids and pulse cyclophosphamide therapy). The treatments have not been effective in many cases and have resulted in other problems resulting from an overuse of steroids.
In many cases, the presence of the skin lesions results in keloid scarring. The use of steroids not only does not prevent the scarring but can lead to thinning of the skin so as to lead to further lesions.
Systemic lupus erythematosus, is a chronic rheumatic disease in which connective tissue throughout the body becomes inflamed. It is an autoimmune disorder in which inflammation is caused by antibodies that attack normal body tissue as if it were an outside invader. The precise cause is unknown, but researchers believe that certain people inherit a genetic predisposition to the disorder, which is then triggered by a virus or some other unidentified environmental factor.
The disease strikes women about 10 times as often as men. It can develop at any age, but is most common in young adults. Symptoms range from so mild that SLE goes undetected for long periods to disabling, even life threatening.
Lupus is often described as the great pretender among Ad diseases because it causes such a wide range of symptoms, the most common of which are fatigue and joint pain. But other manifestations may include a chronic low-grade fever, hair loss, dry eyes and mouth, muscle aches, swollen lymph nodes, loss of appetite, nausea, and mouth ulcers.
About half of all patients develop a butterfly-shaped rash over the nose and cheeks. Depending upon the organs affected, SLE may also cause severe headaches, anemia, inflammation in the lining of the heart or lungs, kidney failure, and mental disorders.
A variationxe2x80x94discoid lupus erythematosusxe2x80x94affects mainly the skin. A rash may appear not only on the face but also on the neck, scalp, and other areas. It ranges from a mild scaliness to a widespread blistery eruption.
As in many other rheumatic disorders, symptoms come and go unpredictably. Sun exposure or stress often produces a flare-up. During pregnancy, symptoms can worsen and cause miscarriage.
It has now been found that mast cells play a role in the formation of the lesions and inflammation. The presence of cathepsin G and elastase in excess results in the poor laying down of tissue so as to result in scarring. The swollen joints result from an inflammatory condition.
Alpha 1-antitrypsin (AT) belongs to the serpin superfamily of serine protease inhibitors. It is a small glycoprotein which is mostly synthesized in the liver and has a molecular weight of 53,000 daltons. Human proteinase inhibitors are involved in the regulation of proteolysis, such as the coagulation pathway, fibrinolysis, tissue destruction by endogenous serine proteinases and inflammation.
U.S. Pat. No. 5,492,889 to Lezdey et al, which is herein incorporated by reference, disclosed the treatment of mast cell tumors by the administration of alpha 1-antitrypsin alone or in combination with other serine protease inhibitors.
The present invention provides a method of treating lupus erythematosus and more particularly to skin eruptions and inflammations resulting from the disease.
According to one embodiment of the invention, there is provided the treatment of symptoms of lupus erythematosus, and in particular, the administration of a serine protease inhibitor. More specifically, according to one embodiment, the treatment provides topically applying a composition containing an effective amount of a serine protease inhibitor selected from the group consisting of alpha 1-antitrypsin, secretory leucocyte protease inhibitor (SLPI), alpha 2-macroglobulin and mixtures thereof to the site of the disease.
Advantageously, the composition includes an effective amount of arginine or an arginine containing amino acid to help in penetration of the drug into the skin.
According to another embodiment of the invention there is provided the treatment of individuals having a lupus disease associated with skin eruptions by treatment with protease inhibitors which prevent the degranulation of mast cells, controls the levels of tryptase, prevent or control the release of histamine and prevent scarring. The treatment includes providing a composition for topical administration. Preferably, a combination therapy is used to treat both the disease and the symptoms.
It is a general object of the invention to provide a composition and method for treating lupus erythematosus.
It is a further object of the invention to prevent scarring by individuals with SLE.
It is yet another embodiment to treat the inflammation which results in patients with SLE.
In accordance with one embodiment of the invention, there is provided a method for the treatment of individuals suffering from lupus erythematosus or symptoms thereof by the administration of a serine protease inhibitor. The method consists of the administration of an effective therapeutic amount of a protease inhibitor selected from the group consisting of alpha 1-antitrypsin, secretory leucocyte, protease inhibitor, alpha 2-macroglobulin or mixtures thereof, and analogs or derivatives thereof in a suitable pharmaceutical carrier.
Accordingly, a composition containing about 0.5 to 10 mg. of protease inhibitor is in a suitable pharmaceutical vehicle is used in the treatment. Generally, for topical use, about 1 to 5 mg. of the protease inhibitor has been effective to treat the eruption and to prevent scarring.
Preferably, about 1 to 5 mg of the protease inhibitor in its natural, transgenic or recombinant form is placed into a composition for topical application such as a cream, gel, ointment or the like. A corticosteroid may be included in the treating composition. The treatment provides immediate relief of pain since the kinins and kallikreins can be controlled. The patient can be treated daily until the lesions are reduced and under normal bodily control. In severe cases, oral corticosteroids may be utilized. The composition may also include penetrating agents such as hyaluronic acid, insulin, liposome, or the like, as well as L-arginine or the arginine containing amino acids. The penetrants may be used in an amount of about 0.5 to 2% by weight of composition. Hyaluronic acid also aids in wound healing.
Systemic lupus erythematosus may also be treated by weekly infusion of 200 mg of the serine protease inhibitor in a 2% saline solution or by oral dosages daily of the inhibitor in a carrier which transgresses the gastric barrier.
It has been found that the incorporation of L-arginine or an arginine containing amino acid having up to ten carbon atoms helps in the penetration of the drug into the skin. The arginine also attracts hormones to the site to help in wound healing.
Serine protease inhibitors have been found to play a major role in the direct inactivation of the mediators of inflammation. The almost immediate disappearance of pain indicates that there can be a control of the kinins as well. A cocktail of serine protease inhibitors, their analogs, salts or derivatives, appears to provide the quickest healing when used in combination with a corticosteroid.
The drug can be administered topically in unit dosage form containing about 1 to 5 mg per day depending on the severity of the disease. The use of controlled release substances, for example, liposomes, diketopyperazine microparticles as disclosed by U.S. Pat. Nos. 5,620,708 and 5,503,852 which are herein incorporated by reference, or an occlusive bandage, are especially effective. One topical composition formed with a vasoline type carrier, such as, AQUAPHOR has been found to be effective.
The inflammatory condition of the joints can be treated by injection at the site of inflammation or by infusion of the drug. Generally, about 200-400 mg of the protease inhibitors can be administered daily by injection or infusion depending on the severity of the disease.
It is understood that the different components used in the treatment of the diseases can be administered in a single unit dose or separately depending upon the patient and the severity of the disease. In most cases, where the patient is a child, the use of a steroid should be avoided.
The corticosteroids which can be used in the treatment of the diseases include triamcinolone acetonide, fluroandrenolide, prednisone, beclomethasone valerate, amcinolone, dexamethasone, betamethasone valerate, halocinonide, clocortolone and hydrocortisone valerate.
The following examples further illustrate the practice of this invention, but are not intended to be limiting thereof. It will be appreciated that the selection of actual amounts of specific protease inhibitor to be administered to any individual patient will fall within the discretion of the attending physician and will be prescribed in a manner commensurate with the appropriate risk: benefit ratio for that particular patient. Appropriate dosages will depend on the patient""s age, weight, sex, stage of disease and like factors uniquely within the purview of the attending physician.


An improved electrosurgical instrument and method is disclosed for reducing smoke generation at a surgical site. The electrosurgical instrument comprises a metal body having an outer insulating layer to reduce thermal/electrical discharge from non-functional portions of the instrument. In one aspect of the invention, an insulating layer having a thermal conductance of about 1.2 W/cm2xc2x0 K and a dielectric withstand strength of at least about 50 volts is employed. Such insulating layer may advantageously comprise silicon and/or carbon. In another aspect of the invention, the metal body is provided to have a thermal conductivity of at least about 0.35 W/cmxc2x0 K, and may advantageously comprise a metal selected from the group: gold, silver, aluminum, copper tantalum, tungsten, columbium and molybdenum. In yet a further aspect, the metal body may include an intermediate layer that defines a peripheral edge portion of reduced cross-section (e.g., about 0.001 inches thick or less) for electrosurgical signal transmission. Such intermediate layer may comprise a metal having a melting point of at least about 2600xc2x0 F. Heat sink means may be included in various embodiments to establish a thermal gradient away from functional portions of the instrument (i.e., by removing heat from the metal body). In one embodiment, the heat sink means may comprise a phase change material that changes from a first phase to a second phase upon absorption of thermal energy from the metal body.

The present invention relates to surgical methods and apparatus for applying an electrosurgical signal to a tissue site to achieve a predetermined surgical effect, and more particularly, to an improved electrosurgical instrument and method to achieve such effect with reduced attendant smoke generation at the surgical site.
The potential applications and recognized advantages of employing electrical energy in surgical procedures continue to increase. In particular, for example, electrosurgical techniques are now being widely employed to provide significant localized surgical advantages in both open and laparoscopic applications, relative to traditional surgical approaches.
Electrosurgical techniques typically entail the use of a hand-held instrument, or pencil, that transfers radio frequency (RF) electrical energy to a tissue site, a source of radio frequency (RF) electrical energy, and an electrical return path device, commonly in the form of a return electrode pad positioned under a patient (i.e. a monopolar system configuration) or a smaller return electrode positionable in bodily contact at or immediately adjacent to the surgical site (i.e. a bipolar system configuration). The waveforms produced by the RF source yield a predetermined electrosurgical effect, namely tissue cutting or coagulation.
Despite numerous advances in the field, currently-employed electrosurgical techniques often generate substantial smoke at the surgical site. Such smoke occurs as a result of tissue heating and the associated release of hot gases/vapor from the tissue site (e.g., in the form of an upward plume). As will be appreciated, any generation of smoke may impede observation of the surgical site during surgical procedures. Additionally, the generation of smoke results in attendant fouling of the atmosphere in the surgical theater. Clearly, these environmental impacts may adversely detract from the performance of medical personnel. Further, there is growing concern that the smoke may be a medium for the transport of pathogens away from the surgical site, including viruses such as HIV. Such concerns have contributed to the use of face shields and masks by surgical personnel.
To date, implemented approaches to deal with smoke have focused on the use of devices that either evacuate the smoke by sucking the same into a filtering system, or that merely blow the smoke away from the surgical site by a pressurized gas stream. Smoke evacuators typically require the movement of large amounts of air to be effective. As such, evacuators tend to be not only noisy but also space consuming. Approaches for blowing smoke away from the surgical site fail to address many of the above-noted concerns, since smoke is not actually removed from the surgical environment. Moreover, both of the above-noted approaches entail the use of added componentry, thereby increasing the cost and complexity of electrosurgical systems.
Accordingly, a primary objective of the present invention is to provide an apparatus and method for use in electrosurgery that results in reduced generation of smoke at a surgical site.
Another objective of the present invention is to provide an apparatus and method for use in electrosurgery that yields less eschar accumulation on the electrosurgical instrument utilized.
An additional objective of the present invention is to provide an apparatus and method for use in electrosurgery that provides for reduced charring along an electrosurgical incision.
Yet another objective is to realize one or more of the foregoing objectives in a manner which does not significantly impact space or cost requirements, and which maintains and potentially enhances the effectiveness of electrosurgical procedures.
In addressing these objectives, the present inventors have recognized that a large portion of the smoke generated utilizing known electrosurgical instruments results from the transmission of electrosurgical energy to tissue from areas of known electrosurgical instruments that are actually intended to be xe2x80x9cnon-functionalxe2x80x9d for purposes of achieving the desired electrosurgical effect (i.e. cutting or coagulation). That is, while known electrosurgical instruments include xe2x80x9cfunctionalxe2x80x9d portions which are designed to be selectively positioned to direct an electrosurgical signal to an intended surgical location (e.g. along a desired incision line), the discharge of energy is not effectively restricted to the functional portions.
More generally in this regard, energy discharge from electrosurgical instruments may be in the form of electrical energy and/or thermal energy. Electrical energy is transferred whenever the electrical resistance of a region between an electrosurgical instrument and tissue can be broken down by the voltage of the electrosurgical signal. Thermal energy is transferred when thermal energy that has accumulated in the electrosurgical instrument overcomes the thermal resistance between the instrument and the tissue (i.e. due to temperature differences therebetween).
The discharge of electrical and thermal energy from nonfunctional areas of known electrosurgical instruments results in unnecessary heating of tissue at a tissue site. In the case of electrical energy discharge, thermal energy is generated as a result of tissue resistance. As the amount of thermal energy at a tissue site increases, the electrical resistance at the surgical site also increases, thereby resulting in the further generation of heat. Such increased heating may in turn result in tissue charring as well as the splattering of tissue matter onto the electrosurgical instrument employed. The splattered tissue matter may accumulate as eschar on the electrosurgical instrument and present a further resistance/heat source to the surgical site. Eschar accumulation on electrosurgical instruments also raises the need for medical personnel to periodically suspend a procedure in order to clean the eschar from the electrosurgical instrument. As can be appreciated, such disturbances can adversely impact an electrosurgical procedure.
In short, the present inventors have recognized that any undesired and unnecessary discharge of electrosurgical energy from non-functional portions of an electrosurgical instrument to a surgical site can have a negative and cascading effect of unnecessary heat generation and resultant smoke generation, eschar build-up on the electrosurgical instrument and unnecessary tissue charring. In the later regard, it is believed that tissue charring may adversely affect healing.
In conjunction with the above-referenced recognition, the present invention provides an apparatus and method for reducing unnecessary/undesired electrical and/or thermal discharge during electrosurgical procedures. Such reduction(s) are achieved via enhanced localization of electrical and thermal energy transmission to a tissue site. More particularly, the present invention markedly reduces electrical/thermal discharge from non-functional areas of an electrosurgical instrument by insulating the nonfunctional areas and/or by providing for an effective level of heat removal away from functional portions of an electrosurgical instrument and/or by otherwise enhancing the localized delivery of an electrosurgical signal to a tissue site.
In this regard, the present invention comprises an electrosurgical instrument that includes a metal body for carrying an electrosurgical signal and an outer insulating layer positioned over at least a portion of the metal body (i.e., a non-functional portion). The metal body includes a main body portion and a peripheral edge portion, the peripheral edge portion being functional for the conveyance of the electrosurgical signal to a tissue site.
In one aspect of the present invention, the outer insulating layer may be advantageously provided to have a maximum thermal conductance of about 1.2 W/cm2-xc2x0 K when measured at about 300xc2x0 K, more preferably about 0.12 W/cm2-xc2x0 K or less when measured at about 300xc2x0 K, and most preferably about 0.03 W/cm2-xc2x0 K when measured at about 300xc2x0 K. For purposes hereof, thermal conductance is intended to be a measure of the overall thermal transfer across any given cross section (e.g. of the insulation layer), taking into account both the thermal conductivity of the materials comprising such layer and the thickness of the layer (i.e. thermal conductance of layer=thermal conductivity of material comprising the layer (W/cmxc2x0 K)/thickness of the layer (cm)). In relation to the foregoing aspect, the insulation layer should also exhibit a dielectric withstand voltage of at least the peak-to-peak voltages that may be experienced by the electrosurgical instrument during surgical procedures. The peak voltages will depend upon the settings of the RF source employed, as may be selected by clinicians for particular surgical procedures. For purposes of the present invention, the insulation layer should exhibit a dielectric withstand voltage of at least about 50 volts, and more preferably, at least about 150 volts. As employed herein, the term dielectric withstand voltage means the capability to avoid an electrical breakdown (e.g. an electrical discharge through the insulating layer).
In one embodiment, the outer insulating layer advantageously comprises a polymeric compound. More particularly, such polymeric compound includes at least about 10% (by weight), and most preferably at least about 20% (by weight), of a component selected from a group comprising: silicon and carbon. In this regard, silicon-based, polymeric insulating layers have been found to be of particular benefit. Such silicon-based, polymeric layers have a thermal conductivity of about 0.003 W/cmxc2x0 K or less when measured at about 300xc2x0 K. Such silicon-based, polymeric layers have been found to be effective when having a thickness of about 0.25 mm or more. Further, such silicon-based, polymeric layers have a dielectric strength of at least about 12 Kv/mm. In a related embodiment, the insulation layer may comprise polytetrafluoroethylene.
In another embodiment, the insulating layer may comprise a ceramic material (e.g., applied to the metal body via dipping, spraying, etc, then cured via drying, firing, etc.). Preferably, the ceramic insulating layer should be able to withstand temperatures of at least about 2000xc2x0 F. The ceramic insulating layer may comprise various metal/non-metal combinations, including for example compositions that comprise the following: aluminum oxides (e.g. alumina and Al2O3), zirconium oxides (e.g. Zr2O3), zirconium nitrides (e.g. ZrN), zirconium carbides (e.g. ZrC), boron carbides (e.g. B4C), silicon oxides (e.g. SiO2), mica, magnesium-zirconium oxides (e.g. (Mgxe2x80x94Zr)O3), zirconium-silicon oxides (e.g. (Zrxe2x80x94Si)O2), titanium oxides (e.g., TiO2) tantalum oxides (e.g. Ta2O5), tantalum nitrides (e.g. TaN), tantalum carbides (e.g., TaC), silicon nitrides (e.g. Si3N4), silicon carbides (e.g. SiC), tungsten carbides (e.g. WC) titanium nitrides (e.g. TiN), titanium carbides (e.g., TiC), nibobium nitrides (e.g. NbN), niobium carbides (e.g. NbC), vanadium nitrides (e.g. VN), vanadium carbides (e.g. VC), and hydroxyapatite (e.g. substances containing compounds such as 3Ca3(PO4)2Ca(OH)2 Ca10(PO4)6(OH)2 Ca5(OH)(PO4)3, and Ca10H2O26P6). One or more ceramic layers may be employed, wherein one or more layers may be porous, such as holes filled with one or more gases or vapors. Such porous compositions will usually have lower thermal conductivity than the nonporous materials. An example of such materials are foam e.g., an open cell silicon carbide foam.
As may be appreciated, in other embodiments the insulating layer may be defined by at least one inner layer (e.g. adjacent to the metal body) that includes a ceramic material, and at least one outer layer that comprises a polymeric compound as noted above. Such inner and outer layers may be advantageously employed to yield an average maximum thermal conductivity of about 0.006 W/cm-xc2x0 K or less where measured at 300xc2x0 K. The inner layer and outer layer may preferably each have a thickness of between about 0.001 and 0.2 inches, and most preferably between about 0.005 and 0.100 inches.
In another aspect of the present invention, the metal body of the inventive electrosurgical instrument may be provided to have a thermal conductivity of at least about 0.35 W/cmxc2x0 K when measured at about 300xc2x0 K. By way of primary example, the metal body may advantageously comprise at least one metal selected from a group comprising: silver, copper, aluminum, gold, tungsten, tantalum, columbium (i.e., niobium), and molybdenum. Alloys comprising at least about 50% (by weight) of such metals may be employed, and even more preferably at least about 90% (by weight). Additional metals that may be employed in such alloys include zinc.
In yet another aspect of the present invention, at least a portion of the peripheral edge portion of the metal body is not insulated (i.e. not covered by the outer insulating layer). In connection therewith, when the outer peripheral edge portion comprises copper such portion may be coated (e.g. about 10 microns or less) with a biocompatible metal. By way of example, such biocompatible metal may be selected from the group comprising: nickel, silver, gold, chrome, titanium tungsten, tantalum, columbium (i.e., niobium), and molybdenum.
In an additional aspect of the invention, it has also been determined that a laterally tapered, or sharpened, uninsulated peripheral edge portion having a maximum cross-sectional thickness which is about {fraction (1/10)} of the maximum cross-sectional thickness of the main body portion is particularly effective for achieving localized electrosurgical signal delivery to a tissue site. In the later regard, it has also been determined preferable that the outer extreme of the peripheral edge portion of the metal body have a thickness of about 0.001 inches or less.
In an additional related aspect of the present invention, the metal body may comprise two or more layers of different materials. More particularly, at least a first metal layer may be provided to define an exposed peripheral edge portion of the metal body that is functional to convey an electrosurgical signal to tissue as described above. Preferably, such first metal layer may comprise a metal having a melting temperature greater than about 2600xc2x0 F., more preferably greater than about 3000xc2x0 F., and even more preferably greater than about 4000xc2x0 F., thereby enhancing the maintenance of a desired peripheral edge thickness during use (e.g. the outer extreme edge noted above). Further, the first metal layer may preferably have a thermal conductivity of at least about 0.35 W/cmxc2x0 K when measured at 300xc2x0 K.
For living human/animal applications, the first metal layer may comprise a first material selected from a group consisting of tungsten, tantalum, columbium (i.e., niobium), and molybdenum. All of these metals have thermal conductivities within the range of about 0.5 to 1.65 W/cmxc2x0 K when measured at 300xc2x0 K. Preferably, alloys comprising at least about 50% by weight of at least one of the noted first materials may be employed, and even more preferably at least about 90% by weight.
In addition to the first metal layer the metal body may further comprise at least one second metal layer on the top and/or bottom of the first metal layer. Preferably, a first metal layer as noted above is provided in a laminate arrangement between top and bottom second metal layers. To provide for rapid heat removal, the second metal layer(s) preferably has a thermal conductivity of at least about 2 W/cmxc2x0 K. By way of primary example, the second layer(s) may advantageously comprise a second material selected from a group consisting of copper, gold, silver and aluminum. Preferably, alloys comprising at least about 50% of such materials may be employed, and even more preferably at least about 90% by weight. It is also preferable that the thickness of the first metal layer and of each second metal layer (e.g. for each of a top and bottom layer) be defined at between about 0.001 and 0.25 inches, and even more preferably between about 0.005 and 0.1 inches.
As may be appreciated, multi-layered metal bodies of the type described above may be formed using a variety of methods. By way of example, sheets of the first and second materials may be role-bonded together then cut to size. Further, processes that employ heat or combinations of heat and pressure may also be utilized to yield a laminated metal body.
In a further aspect of the present invention, the inventive electrosurgical instrument may further comprise a heat sink for removing thermal energy from the metal body. In this regard, the provision of a heat sink establishes a thermal gradient away from the peripheral edge of the metal body, thereby reducing undesired thermal transfer to a tissue site. More particularly, it is preferable for the heat sink to operate so as to maintain the maximum temperature on the outside surface of the insulating layer at about 160xc2x0 C. or less, more preferably at about 80xc2x0 C. or less, and most preferably at 60xc2x0 C. or less. Relatedly, it is preferable for the heat sink to operate to maintain an average metal body temperature of about 500xc2x0 C. or less, more preferably of about 200xc2x0 C. or less, and most preferable of about 100xc2x0 C. or less.
In one approach, the heat sink may comprise a vessel comprising a phase change material that either directly contacts a portion of the metal body (e.g. a support shaft portion) or that contacts a metal interface provided on the vessel which is in turn in direct contact with a portion of the metal body (e.g. a support shaft portion). Such phase change material changes from a first phase to a second phase upon absorption of thermal energy from the metal body. In this regard, the phase change temperature for the material selected should preferably be greater than the room temperature at the operating environment and sufficiently great as to not change other than as a consequence of thermal heating of the electrosurgical instrument during use. Such phase change temperature should preferably be greater than about 30xc2x0 C. and most preferably at least about 40xc2x0 C. Further, the phase change temperature should be less than about 225xc2x0 C. Most preferably, the phase change temperature should be less than about 85xc2x0 C.
The phase change may be either from solid to liquid (i.e., the phase change is melting) or from liquid to vapor (i.e., the phase change is vaporization) or from solid to vapor (i.e., the phase change is sublimation). The most practical phase changes to employ are melting and vaporization. By way of example, such phase change material may comprise a material that is an organic substance (e.g., fatty acids such as stearic acid, hydrocarbons such as paraffins) or an inorganic substance (e.g., water and water compounds containing sodium, such as, sodium silicate (2-)-5-water, sodium sulfate-10-water).
In another approach, the heat sink may comprise a gas flow stream that passes in direct contact with at least a portion of the metal body. Such portion may be a peripheral edge portion and/or a shaft portion of the metal body that is designed for supportive interface with a holder for hand-held use. Alternatively, such portion may be interior to at least a portion of the metal body, such as interior to the exposed peripheral edge portion and/or the shaft portion of the metal body that is designed for supportive interface with a holder for hand-held use. In yet other approaches, the heat sink may simply comprise a thermal mass (e.g. disposed in a holder).
In one arrangement of the present invention, an electrosurgical instrument comprises a main body portion having a blade-like configuration at a first end and an integral, cylindrical shaft at a second end. The main body may comprise a highly-conductive metal and/or multiple metal layers as noted. At least a portion of the flattened blade end of the main body is coated with a ceramic-based and/or silicon-based, polymer insulating layer, except for the peripheral edge portion thereof. The cylindrical shaft of the main body is designed to fit within an outer holder that is adapted for hand-held use by medical personnel. Such holder may also include a chamber comprising a phase-change material or other heat sink as noted hereinabove. Additionally, electrical, push-button controls may be incorporated into the holder for selectively controlling the application of one or more, predetermined, electrosurgical signal(s) from an RF energy source to the flattened blade via the shaft of the main body portion.
In the latter regard, conventional electrosurgical signals may be advantageously employed in combination with one or more of the above-noted electrosurgical instrument features. In particular, the inventive electrosurgical instrument yields particular benefits when employed with electrosurgical signals and associated apparatus of the type described in U.S. Pat. No. 6,074,387, hereby incorporated by reference in its entirety.
Numerous modifications and additions to the present invention will be apparent to those skilled in the art upon consideration of the further description that follows.