Regenerated cellulose food packaging film, including fibrous food casings which has modified cling properties for packaging sausage products. The cellulosic food casings have a fibrous reinforcement impregnated with regenerated cellulose composition which contains from about 0.01 to 2.5 weight percent of admixture of a viscose solution and a food grade cationic resin adhering agent and from about 0.001 to 2.5 weight percent of a protein. The film is prepared by impregnating a tubular fiber reinforcement with a viscose composition containing the resin and protein. The impregnating composition is applied in a single step by injecting the resin and protein into the viscose solution before being extruded into the fibrous web. This assures both even distribution of the polymeric adhering agent and protein in the web, as well as maintenance of a constant level of polymer and protein being applied during the coating process. The degree of cling/adherence of the casing to meat contained in the film is more uniform over the entire circumference of the tubular casing and is almost moisture independent.

The present invention relates generally to improved food packaging films, and more specifically, to food casings having modified release/cling properties for packaging meat products. The food casings may be fiber reinforced or unreinforced and may be used to package both wet and dry meat products.
In the manufacture of processed sausage products, a meat emulsion is prepared from comminuted meat together with fillers, seasonings, spices, etc. A tubular food casing, such as one containing nonedible cellulose, is loaded onto the stuffing horn of a filling machine and stuffed with the meat emulsion. In the case of small sausage products, like frankfurters, the filled casings are twisted, tied or clipped into suitable links at predetermined intervals and further processed. For larger sausage products, like bologna, salami, and the like, the meat emulsion is introduced into larger heavier walled casings or casings having fibrous reinforcements, and formed into chubs or lengthy individual sausage sticks or logs for further processing, e.g., cooking and smoking.
One category of larger meat products includes the so-called dry or semi-dry sausages, sometimes referred to as cervelats or summer sausage, which includes such representative examples as air dried pepperoni, soft salami, hard or dry salami, and the like. As the name suggests, this type of sausage has a reduced moisture content, and its preparation usually includes drying as one step in its manufacture. Dry sausage can also have a lower fat content than other types of sausage products, and depending on the particular type, may also be smoked. Cooking can also be performed in some instances during the smoking step.
Food casings employed in packaging and processing dry or semi-dry sausage products are usually fibrous type casings consisting of a fibrous reinforcement in the form of a web, usually a paper, formed and seamed into a tubular body, impregnated with viscose solution and regenerated in situ. Because the encased meat mass of dry or semi-dry sausage products undergo shrinkage during processing and drying, dry sausage casings preferably have an affinity for the encased meat mass. That is, unless the dry sausage casing adheres to the meat mass during processing and drying, separation between the meat mass and the sidewall of the casing occurs which increases the potential for mold growth, and a final product having an unappetizing appearance. Such products not only have poor customer acceptance, but can also have shorter shelf-life expectancies.
To help overcome the foregoing separation problem with dry/semi-dry sausage products, fibrous regenerated cellulose casings have been developed with polymeric coatings consisting of thermosetting resins to enhance the cling or adherence properties between the meat mass and the inner side wall of the casing. One such example is disclosed in U.S. Pat. No. 3,378,379, which teaches a dry fibrous sausage casing having a cationic thermosetting resin coating on the casing surface in contact with the packaged meat.
While the coated casing of U.S. Pat. No. 3,378,379, may be useful in allowing the passage of moisture from the meat mass during drying, ingress of smoke to the meat during smoking, and adherence to the meat mass as the meat shrinks due to loss of moisture, such casings and methods of manufacture have not been entirely satisfactory for all types of dry and semi-dry sausage products. In this regard, it was found that dry sausage type fibrous casings, including the type of casings coated according to the methods of U.S. Pat. No. 3,378,379, with cationic thermosetting resins, can exhibit excessively high cling characteristics, and cannot be readily used with all types of dry sausage recipes because of an imbalance between cling/adherence and release properties. Furthermore, the cling of such casing varies with the amount of moisture in the sausage product.
For example, certain dry sausage recipes, like dipped style products favored by many Europeans require partial removal of casing by meat processors during the latter stages of preparation after cooking and drying. For this to readily occur, the dry sausage casing must have a sufficiently low level of cling to permit easy manual peeling of the casing from the meat mass without damaging the product. In preparing dipped style dry sausage the casing is entirely removed, except for the end portion holding the support string or metal end-closure cap for suspending the product during the final stages of processing. The remaining unpeeled casing end must continue to adhere to the meat mass for support and prevent falling to the floor during the final stages of processing, e.g., dipping into gelatin and condiments, e.g., pepper, cheese, roasted onions, etc. Hence, for such dry sausage recipes packaging films/casings require a balance of both cling/adherence properties and release characteristics. Too much cling and not enough release will make manual peeling a slow, arduous task for high production efficiency. Whereas, too high release and not enough cling will make the dipping process difficult to perform. It would further be desirable if the cling/adherence of such casings were constant regardless of the amount of residual moisture in the sausage product.
U.S. Pat. No. 3,378,379 discloses methods for enhancing the cling properties of dry sausage casing by applying internal coatings of cationic thermosetting resin by the known xe2x80x9csluggingxe2x80x9d or xe2x80x9cbubblexe2x80x9d technique. Following impregnation of the fibrous tubular web with viscose solution by drawing through an annular die; regeneration of the casing and passage through a glycerin/water bath, an aqueous solution of the thermosetting resin is introduced through a cut in the casing by known methods, e.g., U.S. Pat. No. 3,378,379, which resin is maintained between rolls of the coating station. The regenerated casing is continuously drawn between the rolls where the interior wall of the casing is automatically coated with the resin solution. Squeeze rolls remove excess resin from collecting on the casing interior wall. Following coating, the casing is drawn through a drying chamber where it is inflated by a bubble of air and dried.
While the bubble technique may be widely practiced in applying release/cling coatings to casing surfaces, it has several short-comings. The bubble method is dependent on many process variables making it difficult to achieve product uniformity and quality control. This is due to such variables as rate of casing travel; initial concentration of the coating solution; rate of exhaustion and depletion of resin from the coating solution; amount of pressure applied by the squeeze rolls, etc. Such factors determine the amount of resin with which the inner wall of the casing will be coated and the frequency with which the coating composition will require replenishing. Liquid transfer from tanks can also dilute the bubble in standard operations. Because the resin in solution between the rolls is constantly being depleted from the casing interior the coating being applied lacks uniformity and produces a xe2x80x9ctwo side effectxe2x80x9d, i.e., different meat cling over the circumference of the casing. The bubble method of coating can also result in xe2x80x9cropingxe2x80x9d and xe2x80x9ccarry overxe2x80x9d of the casing where multiple folds of casing prevent removal of chemicals.
In order to avoid the above described problems, it has been suggested that certain resins could be incorporated into viscose used to form the casing either by extruding the resin containing viscose in the form of a tubular film or by impregnating a tubular fiber reinforcement with the resin containing viscose. Such a method and product is described in European Patent Application 0.635.211, published Jan. 25, 1995, which is the equivalent of copending U.S. patent application Ser. No. 08/096,320, filed Jul. 23, 1993, from which priority is claimed. While the method described in European Patent Application 0.635.211 was an improvement over prior methods for controlling adhesion to meat product within a food casing, due to the nature of adhering resins it was difficult to xe2x80x9cfine tunexe2x80x9d adherence characteristics in a reproducible manner which are similar under both wet and dry conditions.
Accordingly, there is a need for modified fibrous type food casings particularly for dry and semi-dry sausage products which offer a better balance between adherence/cling and release properties. In particular, there is need for more efficient methods of preparing fibrous casings with low cling properties where such properties can be replicated with better quality control and uniformity between production runs through less manual handling (bubble changes), automatic dosing of the adhering agent, and more consistent amounts of adhering agent being applied. There is further a need for being able to fine tune adherence characteristics for various food casing products which are similar under both wet and dry conditions.
It is therefore a general object of the invention to provide for fibrous reinforced food packaging films, and particularly food casings having predictably modified cling or release properties with the food-stuff packaged therein regardless of moisture content.
More specifically, it is a principal object of the invention to provide for fibrous reinforced food packaging films, including tubular food casings having cling/adherence properties which are especially useful in packaging dry or semi-dry sausage or summer sausage products, such as pepperoni, hard and semi-soft salamis, and the like.
It is yet a further object to provide for novel fibrous food casings for facilitating the production of special dry sausage recipes requiring reduced levels of cling, or more balance between adherence/cling and release properties with the packaged foodstuff.
It is yet a further object of the invention to provide for a method of preparing regenerated cellulose food casings having a fibrous reinforcement in the form of a tubular body with interior and exterior wall surfaces by the steps of impregnating the surfaces with a viscose solution and regenerating the casing, wherein the improvement comprises the steps of forming a coating composition comprising a novel admixture of the viscose with additives which imparting to the casing cling properties for the food product packaged therein which have the desired adherence/cling characteristics which are reproducible and almost constant under wet and dry conditions.
These and other objects, features and advantages will become more apparent from a reading of the following more detailed description of the invention.
The invention comprises a regenerated cellulose food packaging film, including fibrous food casings which has modified cling properties for packaging sausage products. The cellulosic food casings preferably have a fibrous reinforcement impregnated with regenerated cellulose vicose composition which contains from about 0.01 to 2.5 percent of a food grade cationic resin adhering agent by weight of cellulose and from about 0.001 to 2.5 weight percent of a protein by weight cellulose. The film is prepared by impregnating a tubular fiber reinforcement with a viscose composition containing the resin and protein. The impregnating composition is applied in a single step by injecting the resin and protein into the viscose solution before being extruded as a tubular film or into a fibrous web. This assures both even distribution of the polymeric adhering agent and protein in the food casing, as well as maintenance of a constant level of polymer and protein being applied during the coating process. The degree of cling/adherence of the casing to meat contained in the film is more uniform over the entire circumference of the tubular casing and is almost moisture independent. The food packaging film is usually a tubular food casing which may be unreinforced or reinforced, e.g. with a fibrous web. The food packaging film is most commonly a fiber reinforced tubular sausage casing. The invention also includes a method for manufacture of the above food packaging films.
The modified package can be in the form of regenerated cellulose food packaging films and tubular shaped food casings. The invention contemplates casings being supplied as relatively short individual precut lengths of flat, unshirred tubular material, as well as extended lengths of flat unshirred tubular material wound on large storage and dispensing reels. The present invention also contemplates tubular casings pleated into shirred strands or sticks for convenient handling and efficient production during stuffing operations.
The regenerated cellulose packaging films and casings usually comprise a fibrous reinforcement, typically paper, which is impregnated with a novel coating composition. The composition prior to being applied to the reinforcement comprises viscose solution in admixture with a combination food grade cationic polymeric adhering agent and a protein for imparting cling between the film/casing and food product engaged therewith. That is, instead of applying the thermosetting resin as a separate coating to the web after impregnation and regeneration of a viscose-containing web it was discovered that desirable, predictable and reproducible cling/adhering properties can be imparted to the film in a step prior to film formation by injecting a predetermined amount of a resin protein mixture into the viscose solution prior to impregnating the fibrous reinforcement. Thus, the resin and protein in a ratio known to give a predictable adherence characteristic under both wet and dry conditions is applied as a component of the viscose solution in the form of an admixture simultaneously during impregnation of the fibrous web.
It was also found that fibrous webs impregnated with viscose-containing compositions as disclosed herein together with a food grade cationic polymeric adhering agent in admixture with a protein imparts a more uniform and reduced level of cling/adherence between the packaging film and meat mass than other known regenerated cellulose casings having separate coatings of such agents.
For purposes of the present invention, expressions such as xe2x80x9creducedxe2x80x9d or xe2x80x9clow level cling propertiesxe2x80x9d are intended to refer to casings of this invention which readily allow manual separation from a processed or partially processed and packaged meat product without damaging the meat mass during removal. End portions of casing remaining in-tact are capable of supporting the weight of the meat product without premature separation from the meat mass.
Viscose, as used herein, includes traditional xanthate viscose as well as solutions of cupra-ammonium and carbamate derivatized cellulose. As used herein, viscose also includes true solutions of cellulose, e.g. in tertiary amine oxide.
The preferred embodiments of the invention relate principally to fibrous reinforced food casings, mainly for semi-dry and dry sausage products; however, the same invention may be applied to unreinforced food casings and xe2x80x9cwetxe2x80x9d meat product. In a preferred embodiment, the casings comprise a tubular shaped fibrous web of conventional form having an interior and exterior side wall impregnated with a coating composition. The coating composition comprises a viscose solution in the form of an admixture with a cationic polymeric adhering agent and protein for imparting cling properties for a food to be stuffed therein. Optionally, but preferably, it will be more convenient to have both the interior and exterior sidewalls of the casing impregnated with the coating composition containing the cationic polymeric adhering agent.
Generally, the fibrous reinforcements for the casings are prepared from fibers approved for use in food wrapping applications. Although not limited to, they include for instance, any cellulosic material, and particularly high strength fibers, as for example, Philippine hemp fibers, cotton fibers, wood fibers, and their derivatives. Embodiments of fibrous reinforcements are intended to include naturally occurring cellulosic material impregnated in slurry form, but more preferably in the form of a web. That is to say, one embodiment involves food wrappings prepared with webs or sheets of woven, but preferably nonwoven fibers which includes various types of paper and paper products. In most instances, the reinforcement of choice is the most economic fibrous web which will impart the required strength and other characteristics which are consistent with the properties of the casings described herein. Other desirable reinforcements may be prepared in addition to those mentioned above. They include mixtures of Philippine hemp fibers with long fibered soft wood fibers, or mixtures of soft wood fibers with synthetic rayon paper making fibers or textile rayon fibers, etc. Synthetic webs prepared from woven, nonwoven, and even spun fibers like polyesters, such as available under the DuPont(trademark) xe2x80x9cReemayxe2x80x9d; or various polyamides like nylon 6; nylon 6,6,etc., may also be employed.
The binder for impregnation of the fibrous reinforcement is a composition comprising viscose solution in combination with the cationic polymeric adhering agent and protein. The resin and protein being present in a sufficient amount to impart predictable and reproducible low level cling/adherence properties to the casing when in contact with a meat mass, e.g., sausage emulsion. The cling properties are similar under both wet and dry conditions. As previously discussed, low levels of cling are intended to denote that amount of adherence which enables facilitating manual separation of the casing from the meat mass, which may be partially processed. The process of separation and removal of the casing is facilitated without stripping meat from the surface of the meat mass. Adherence characteristics, i.e., cling and release, may be balanced, so end portions of the casing, for example, remaining on the meat mass after partial peeling, have sufficient cling to remain in tact for support of the meat mass during any remaining processing steps, such as dipping without prematurely separating.
The casings have a fibrous reinforcement comprising a generally tubular shaped web having interior and exterior walls with at least the interior wall being uniformly impregnated with an impregnating (coating) composition. Advantageously, casings impregnated with the compositions have more evenly applied cling type resins. The casings can be more readily separated and removal facilitated from the meat product during processing than regenerated cellulose casings prepared with similar type resins or proteins, but applied as separate coatings, such as by the bubble technique. The food grade polymeric adhering agent is present in the viscose-containing impregnating composition in a sufficient amount to impart low level cling properties to the film in conjunction with the protein when the regenerated viscose is in contact with the foodstuff. More specifically, the impregnating composition comprises from about 0.01 to less than about 2.5 percent by weight of cellulose and preferably from 0.01 to less than 0.75 percent by weight of cellulose of a food grade cationic polymeric adhering agent (resin) which, for example, may be an epoxy substituted polysecondary amine, or alternatively, a melamine-formaldehyde polymer.
Preferred polymeric adhering agents include certain food grade thermosetting aldehyde polymers like the amino resins, such as melamine formaldehyde polymers. They are commercially available from American Cyanamide under the trademark ACCOBOND. ACCOBOND 3524, for example, is a highly methylolated melamine-formaldehyde precondensate. Other suitable polymeric adhering agents include the water soluble epoxy-substituted polysecondary amine thermosetting resins. Generally, they are condensates of epichlorohydrin and a polyamide. That is oligomers or higher molecular weight resinous materials having a plurality of secondary amine groups, e.g., polyamide amines, polyurea amines, and the like. The epoxy substituted polysecondary amine cationic thermosetting adhering agents are preferably condensation products of epichlorohydrin and a polyamine prepolymer formed from a dicarboxylic acid, such as adipic acid, glutaric acid and succinic acid, and a diethylenetriamine. Variations of the epoxy substituted poly-secondary amines may be useful adhering agents by modifying the internal structure of the diethylenetriamine and/or by employing alternative dicarboxylic acids, such as those mentioned above. Particularly useful cationic thermosetting adhering agents are commercially available from Hercules, Inc., under the trademark KYMENE(copyright), e.g., grade 557. Such products are also known as Hercules Resin 2000 or RESAMINE(copyright) which are also water soluble thermosetting cationic polymers, i.e., reaction products of epichlorohydrin and adipic acid-diethylenetriamine polyamide.
Specific examples of suitable resins are polyamine-polyamide resins, polyethyleneimine resins and vinyl amine-N vinyl formamide combination resins. Acceptable polyamine-polyamide resins are commercially sold under the trademarks KYMENE 557H and KYMENE SLX by Hercules, RESAMINE 3632 and RESAMINE 3608 by Hoechst and LURESIN KTU by BASF. Suitable polyethylene-imine resins are sold under the trademarks LUPASOL SK and LUPESOL P by BASF and suitable vinyl amine-N vinyl formamides are sold under the trademark BASOCOL PR8086 by BASF.
The protein is used in conjunction with the resin in an amount of from 0.001 to 2.5 weight percent based upon cellulose content. The ratio of resin to protein is from 100:1 to 1:1 and preferably from 100:1 to 10:1. The protein content is usually about 0.04 to 0.10 percent by weight of cellulose.
A wide range of proteins can be used in accordance with the present invention such as soy protein, gelatine, collagen and plasma.
Causticized xanthate viscose solutions typically have high pHs in the range of about 9 to 12. To prevent pH shock between the lower pH polymeric adhering agent and viscose solution it has been found advantageous to buffer the compositions to a pH generally in the range from about 7.5 to about 12, and more preferably, to pHs from about 9 to about 11 with ammonia solution (26 percent).
The regenerated cellulosic fibrous food casings of the invention are manufactured using standard equipment employed by casing manufacturers they may be prepared, for instance, by impregnating a fibrous web by extruding the viscose-containing coating compositions of the invention into a fibrous web using a coating die of conventional design, such as a double viscose coating die which continuously coats both the inner and outer sidewalls of the tubular web. The coated tubular web is then regenerated in a coagulating bath. The regenerated gel casing is then washed and plasticized, usually in a glycerine-containing bath. The plasticized gel film is inflated and passed through lengthy gas fueled hot air dryers where the moisture content of the casing is reduced to a relatively low level, e.g., 5 to 10 percent. The dried casings may be shirred into tightly compressed strands, rolled as flat stock onto reels, etc., and packaged.
In practice, the cationic polymeric adhering agent protein mixture is injected into the viscose solution before being extruded into the fibrous web. This assures both even distribution of the polymeric adhering agent and protein in the web, as well as maintenance of a constant level of polymer being applied during the coating process. As a result, the degree of cling/adherence of the casing to the meat mass is uniform over the entire circumference of the tubular casing and is reproducible. The cling characteristics are similar under both wet and dry conditions.
The following examples serve to illustrate and not limit the present invention.

Food casings having modified release properties and methods of manufacture


A composite heat dissipation assembly having a net shape injection molded thermally conductive elastomeric heat sink and at least one integral heat pipe is provided in the present invention. The molded conformable heat sink is formed from a base elastomeric material that is loaded with thermally conductive filler. The base material is mixed with the filler and net shape molded to form the outer geometry of the assembly. Within the geometry of the part an integral channel is formed that is capable of receiving a heat pipe. The channel is formed to have an opening that is slightly smaller than the outer cross-sectional dimensions of the heat pipe. When the heat pipe is pressed into the channel a portion of the elastomeric material is compressed and the reactionary force of the compressed material firmly presses the elastomer into thermal communication with the outer surface of the heat pipe. In addition, the manner in which the elastomer mates to the surface of the heat pipe reduces junction resistance between the surface of the heat pipe and the outer component, thereby eliminating the need to use glue or conformable thermal interface to assemble the part.

The present invention relates generally to a new composite assembly for transferring heat generated within electronic devices from areas of high heat generation potential to areas of high heat dissipation potential. More specifically, this invention relates to an injection molded thermally conductive elastomeric part having an integral pocket for receiving a heat pipe component.
In the electronics industry, there are various parts and components, which generate heat during operation. For example, it is well known that most computer components generate heat during operation. Various types of electronic device packages and integrated circuit chips, such as the PENTIUM central processing unit chip (CPU) manufactured by Intel Corporation and RAM (random access memory) chips are such devices that generate heat. These integrated circuit devices, particularly the CPU microprocessor chips, generate a great deal of heat during operation, which must be removed to prevent adverse effects on operation of the system into which the device is installed. For example, a PENTIUM microprocessor, containing millions of transistors, is highly susceptible to overheating, which could destroy the microprocessor device itself or other components proximal to the microprocessor.
There are a number of prior art methods to cool heat generating components and objects to avoid device failure and overheating, as discussed above. A block heat sink or heat spreader is commonly placed into thermal communication with the heat-generating surface of the object to absorb and dissipate the heat therefrom. Such a heat sink typically includes a base member with a number of individual cooling members, such as fins, posts or pins, to assist in the dissipation of heat. The geometry of the cooling members is designed to increase the total surface area of the heat sink that is in contact with the ambient air for optimal heat dissipation. The use of such fins, posts of pins in an optimal geometrical configuration greatly enhances heat dissipation compared to devices with no such additional cooling members, such as a flat heat spreader.
To further enhance the overall heat dissipation of an assembly, fans have been installed either internally or externally to increase the airflow over the heat dissipation device. However, these devices consume power and have numerous moving parts. As a result, heat sink assemblies with this type of active devices are subject to failure and are much less reliable than a device that is solely passive in nature.
It has been discovered that as an alternative to the active cooling devices described above, more efficient cooling of electronics can be obtained using passive heat pipes that require no external power source and contain no moving parts. Heat pipes of this type are well-known devices that are employed for efficiently moving heat from one place to another. Generally, the heat pipe is in the form a vacuum-tight vessel having a particular geometric shape, which is evacuated and partially filled with a working fluid. The heat pipe passively transfers heat from a heat source to a heat sink where heat is dissipated. As the heat is conducted into the heat pipe from the heat-generating source, the fluid is vaporized in an evaporator section causing a pressure gradient to develop in the heat pipe. This gradient forces the vapor to flow along the heat pipe to the condenser section, where the vaporized fluid condenses back to its liquid state by giving up its latent heat of vaporization. The working fluid in a liquid state is then returned to the evaporator section to repeat the process of removing the heat generated by the heat source. One method used to achieve cooling by use of a heat pipe places the evaporator section at the lower end and the condenser section at the upper end where the heat pipe is in a substantially vertical position. Once the working fluid has been condensed, the liquid flows by gravity back to the evaporator section. In addition, internal wick structures may be used to assist liquid flow back to the evaporator section through capillary action thereby reducing the effect of gravity on the device.
Alternatively, the heat pipe may be simply filled with the working fluid to create a vapor chamber therein when the liquid is heated by the heat-generating object to its vaporization point. It is well known in the prior art that vaporized water or ammonia is highly thermally conductive and greatly facilitates the transfer of heat.
While heat pipes are highly effective for transferring heat from one point to another, heat pipes are typically tubular in configuration and do not interface well with objects to be cooled. Further, heat pipes, due to their tubular configuration, do not have a significant surface area, preventing them from interfacing well with the ambient air for dissipation of heat. For example, a typical heat pipe may be a tube having a diameter of less than a centimeter while the object to be cooled may be a microprocessor, which is two inches square in shape. Due to the severe mismatch in geometry, affixing such a heat pipe to a microprocessor results in a very inefficient transfer of heat from the large heat generating surface to the small surface area, about one side of the diameter, of a heat pipe. Further, the exposure of the free end, not connected to a heat generating object, to the ambient air is also inefficient because the surface area of the diameter of the heat pipe is relatively small thus making the dissipation of heat even more inefficient.
In order to enhance the efficiency for the interface ends of the heat pipe, it is desirable to cast a heat sink assembly or overmold a thermally conductive configuration about the heat pipe to increase the overall contact surface area. However, in so doing, there is a serious risk of damage to the heat pipe during the casting or molding process. If the casing of the heat pipe is cracked or split during formation of the overmolded configuration, the heat pipe media will leak and the heat pipe will not operate properly, resulting in a deleterious effect on the thermal conductivity of the overall heat dissipation device.
In view of the foregoing, there is a demand for a heat pipe construction and a method for manufacturing such a construction that is less expensive than the prior art yet provides superior heat dissipation. There is a demand for a passive heat pipe construction with no moving parts that can provide heat dissipation without the use of active components. In addition, there is a demand for a method of manufacturing a heat pipe construction that enables a heat pipe to be incorporated into an assembly that includes additional heat dissipating material, without the risk of damage to the heat pipe itself.
In this regard, in accordance with the present invention, a composite assembly that has the capacity to conduct heat from an area of high heat generating potential to an area of high heat dissipation potential is provided. One component of the part is net shape injection molded from a thermally conductive elastomeric material to create the required geometry for the proper interfacing and heat dissipating configurations and has an integrally molded channel to receive a heat pipe. The molded component is formed from a base elastomeric matrix material that is loaded with thermally conductive filler. The base material is mixed with the filler and injected into a mold cavity to form the outer geometry of the assembly. Within the geometry of the part an integral channel is formed that is capable of receiving a heat pipe. Since the heat pipe channel is formed in the elastomeric composite, the walls of the channel have resilient and conformable properties.
The geometry of the channel is formed in such a manner so as to have an opening that is slightly smaller that the outer cross-sectional dimensions of the heat pipe. When the heat pipe is pressed into the channel a portion of the elastomeric material is compressed and the reactionary force of the compressed material firmly presses the elastomer into thermal communication with the outer surface of the heat pipe. This allows the outer component of the assembly to be net shape molded into virtually any required geometric configuration, including very thin profiles that were previously unattainable in the prior art using traditional over molding methods. In addition, the manner in which the elastomer mates to the surface of the heat pipe reduces junction resistance between the surface of the heat pipe and the outer component, thereby eliminating the need to use thermally conductive glues, greases or conformable thermal interfaces to assemble the part.
Another feature of the present invention is the fact that the elastomeric portion of the present invention has geometry that is flexible and conformable. This allows the construction of a flexible heat pipe assembly that is quite useful in compact assemblies with limited space through which to conduct waste heat. Also, the conformability of the elastomeric material allows it to be installed directly in contact with the heat generating surface and the heat-dissipating surface without the additional requirement of an interface pad. The elastomeric material is capable of overcoming and conforming to the slight surface imperfections that occur from the fabrication techniques of those surfaces thus resulting in superior thermal interface.
Further, the method used in manufacturing the present invention is superior In that it eliminates several steps as compared to the prior art. By first net shape molding the outer component into the desired geometric configuration additional steps associated with machining and polishing the parts into the finished shape are eliminated. Also, by pressing the heat pipe into the conformable channel after the part is formed, the heat pipe can be fully charged before incorporation into the assembly.
A single heat pipe is preferably employed but multiple heat pipes may be embedded within the construction of the present invention. Alternatively, other heat transfer conduits may be employed instead of a heat pipe, such as copper rods or formed copper strands. In addition, optional flat contact ends are can be provided in the overall part geometry proximal to where the ends of the heat pipe reside in its installed position to achieve greatly improved thermal interface results in a manner that is far less expensive than soldering a heat pipe to a heat spreader.
It is therefore an object of the present invention to provide an improved composite heat dissipation composite assembly that can provide enhanced heat dissipation for a heat generating component or object. It is a further object of the present invention to provide a heat pipe construction device that has no moving parts. Another object of the present invention is to provide a composite heat pipe construction that is completely passive and does not consume power. A further object of the present invention is to provide a heat pipe construction that inexpensive to manufacture. It is yet another object of the present invention to provide a conformable elastomeric heat sink geometry into which a heat pipe can be installed after the part is molded with out the requirement of thermal interfaces or adhesives. A further object of the present invention is to provide a method of manufacturing a conformable composite heat pipe construction that is moldable and is easy to assemble manufacture.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.

Thermally conductive elastomeric heat dissipation assembly with snap-in heat transfer conduit


A multilayer laminate suitable for use as a packaging film, more particularly for use as a chemical barrier packaging film, and suitable for packaging products such as motor oils and solvent impregnated cloths. The package is useful in applications which allow users to avoid the need to use spray bottles to dispense solvents, thus protecting users from inhaling hazardous chemicals from the air.

1. Field of the Invention
The invention relates to a multilayer laminate suitable for use as a packaging film. More particularly, the invention pertains to a multilayer laminate for use as a chemical barrier packaging film and suitable for packaging products such as solvent impregnated materials and motor oils.
2. Description of the Related Art
Packaging films are well known multilayered structures which may be used to store a variety of products. Regardless of the type of product stored in the package, it is necessary that the package be capable of sealing the product from contact with the atmosphere surrounding the package. For example, if the package is used to store a food product, it is necessary that the package be tailored to have good moisture and oxygen barrier properties to prevent the food from spoiling. Packaging films must also be capable of containing the product without the film degrading due to the type of product. For example, when storing chemical compositions or solvents it is important that the chemical or solvent does not corrode the package. This is particularly a concern with certain organic solvents. Organic solvents enjoy diverse application in a multitude of industries. One typical use for organic solvents is as a cleanser. In general, it is necessary to package such cleansers in plastic spray bottles that are strong enough to store the solvent without being eaten away by the solvent. However, using spray bottles to dispense an organic solvent or cleanser can cause a dangerous condition for workers who might inadvertently inhale the spray. It has therefore become useful in the art to provide a disposable cloth impregnated with an organic solvent or other cleanser without the need for a spray bottle. A consumer can thereby use the solvent impregnated cloth and dispose of it when it is no longer useful.
Although solvent impregnated cloths are available as rolls, as bulk-like baby wipes, or in loose form in bulk packages, it would be advantageous to produce such solvent impregnated cloths in individually wrapped chemical barrier packages. It is further desirable that such a package be flexible so that it can be easily stored and discarded after use of the product inside.
The invention provides a multilayered chemical barrier film comprising:
a) an inner layer comprising an unoriented nylon;
b) a middle layer comprising either a polyolefin, a metal foil, or a polyester attached to a surface of the inner layer; and
c) an outer layer comprising either a polyolefin or a polyester attached to a surface of the middle layer;
such that when the middle layer comprises a polyolefin, the outer layer comprises a polyester, and when the middle layer comprises a polyester, the outer layer comprises a polyolefin.
The invention also provides a package comprising a casing which defines an inner compartment, said casing comprising a pair of overlapping chemical barrier films, each of said chemical barrier films comprising in order from the inner part of the package to the outer part of the package:
a) an inner layer comprising an unoriented nylon;
b) a middle layer comprising either a polyolefin, a metal foil or a polyester attached to a surface of the inner layer; and
c) an outer layer comprising either a polyolefin or a polyester attached to a surface of the middle layer;
such that when the middle layer comprises a polyolefin, the outer layer comprises a polyester, and when the middle layer comprises a polyester, the outer layer comprises a polyolefin,
and wherein the overlapping chemical barrier films are sealed together by directly attached portions of the inner nylon layers around a perimeter of the inner nylon layers.
The invention further provides a package comprising a casing which defines an inner compartment, said casing comprising a single chemical barrier film, said chemical barrier film comprising in order from the inner part of the package to the outer part of the package:
a) an inner layer comprising an unoriented nylon;
b) a middle layer comprising either a polyolefin or a polyester attached to a surface of the inner layer; and
c) an outer layer comprising either a polyolefin, a metal foil, or a polyester attached to a surface of the middle layer;
such that when the middle layer comprises a polyolefin, the outer layer comprises a polyester, and when the middle layer comprises a polyester, the outer layer comprises a polyolefin,
and wherein the chemical barrier film is folded at an edge and sealed to itself by directly attached portions of the inner nylon layer around at least a portion of perimeter of the inner nylon layer.
The present invention provides a solution to the needs mentioned above.
A multilayer laminate is provided which acts as a chemical barrier and may be formed into a storage bag or container for motor oils, solvent impregnated cloths, other products. Such containers may be easily stored and disposed after product use. The nylon layer provides resistance to chemicals as well as a heat seal layer. The polyester or metal foil layer permits retention of the solvent in the package, for example. The polyolefin layer provides added strength, flexibility and puncture resistance to the structure.
In the production of a chemical barrier film according to the invention, an inner layer, a middle layer and an outer layer are attached together to form a multilayered film. While the type of composition comprising the middle and outer layers may vary, it is important to the scope of the invention that the inner layer comprise an unoriented nylon structure.
Suitable nylons within the scope of the invention for use in the inner layer non-exclusively include homopolymers or copolymers selected from aliphatic polyamides and aliphatic/aromatic polyamides having a molecular weight of from about 10,000 to about 100,000. General procedures useful for the preparation of polyamides are well known to the art. Such include the reaction products of diacids with diamines. Useful diacids for making polyamides include dicarboxylic acids which are represented by the general formula
HOOCxe2x80x94Zxe2x80x94COOH
wherein Z is representative of a divalent aliphatic radical containing at least 2 carbon atoms, such as adipic acid, sebacic acid, octadecanedioic acid, pimelic acid, suberic acid, azelaic acid, dodecanedioic acid, and glutaric acid. The dicarboxylic acids may be aliphatic acids, or aromatic acids such as isophthalic acid and terephthalic acid. Suitable diamines for making polyamides include those having the formula
H2N(CH2)nNH2
wherein n has an integer value of 1-16, and includes such compounds as trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, hexadecamethylenediamine, aromatic diamines such as p-phenylenediamine, 4,4xe2x80x2-diaminodiphenyl ether, 4,4xe2x80x2-diaminodiphenyl sulphone, 4,4xe2x80x2-diaminodiphenylmethane, alkylated diamines such as 2,2-dimethylpentamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 2,4,4 trimethylpentamethylenediamine, as well as cycloaliphatic diamines, such as diaminodicyclohexylmethane, and other compounds. Other useful diamines include heptamethylenediamine, nonamethylenediamine, and the like.
Useful polyamide homopolymers include poly(4-aminobutyric acid) (nylon 4), poly(6-aminohexanoic acid) (nylon 6, also known as poly(caprolactam)), poly(7-aminoheptanoic acid) (nylon 7), poly(8-aminooctanoic acid)(nylon 8), poly(9-aminononanoic acid) (nylon 9), poly(10-aminodecanoic acid) (nylon 10), poly(11-aminoundecanoic acid) (nylon 11), poly(12-aminododecanoic acid) (nylon 12), nylon 4,6, poly(hexamethylene adipamide) (nylon 6,6), poly(hexamethylene sebacamide) (nylon 6,10), poly(heptamethylene pimelamide) (nylon 7,7), poly(octamethylene suberamide) (nylon 8,8), poly(hexamethylene azelamide) (nylon 6,9), poly(nonamethylene azelamide) (nylon 9,9), poly(decamethylene azelamide) (nylon 10,9), poly(tetramethylenediamine-co-oxalic acid) (nylon 4,2), the polyamide of n-dodecanedioic acid and hexamethylenediamine (nylon 6,12), the polyamide of dodecamethylenediamine and n-dodecanedioic acid (nylon 12,12) and the like. Useful aliphatic polyamide copolymers include caprolactam/hexamethylene adipamide copolymer (nylon 6,6/6), hexamethylene adipamide/caprolactam copolymer (nylon 6/6,6), trimethylene adipamide/hexamethylene azelaiamide copolymer (nylon trimethyl 6,2/6,2), hexamethylene adipamide-hexamethylene-azelaiamide caprolactam copolymer (nylon 6,6/6,9/6) and the like. Also included are other nylons which are not particularly delineated here.
Of these polyamides, preferred polyamides include nylon 6, nylon 6,6, nylon 6/6,6as well as mixtures of the same. Of these, nylon 6 is most preferred. It is also preferred that the nylon be heat sealable.
Aliphatic polyamides used in the practice of this invention may be obtained from commercial sources or prepared in accordance with known preparatory techniques. For example, poly(caprolactam) can be obtained from Honeywell International Inc., Morristown, N.J. under the trademark CAPRON(copyright).
Exemplary of aliphatic/aromatic polyamides include poly(tetramethylenediamine-co-isophthalic acid) (nylon 4,I), polyhexamethylene isophthalamide (nylon 6,I), hexamethylene adipamide/hexamethylene-isophthalamide (nylon 6,6/6I), hexamethylene adipamide/hexamethyleneterephthalamide (nylon 6,6/6T), poly (2,2,2-trimethyl hexamethylene terephthalamide), poly(m-xylylene adipamide) (MXD6), poly(p-xylylene adipamide), poly(hexamethylene terephthalamide), poly(dodecamethylene terephthalamide), polyamide 6T/6I, polyamide 6/MXDT/I, polyamide MXDI, and the like. Blends of two or more aliphatic/aromatic polyamides can also be used. Aliphatic/aromatic polyamides can be prepared by known preparative techniques or can be obtained from commercial sources. Other suitable polyamides are described in U.S. Pat. Nos. 4,826,955 and 5,541,267.
Attached to a surface of the inner nylon layer is a middle layer, and attached to an opposite surface of the middle layer is an outer layer. The middle layer may comprise either a polyolefin, a metal foil or a polyester, while the outer layer may comprise either a polyolefin or a polyester. Preferably, the metal foil is an aluminum foil. Although it is not conventionally known to incorporate metallic foils other than aluminum foils in multilayered packaging films, it is within the scope of the invention that any metallic foil, such as a copper foil or a nickel foil, may be used if desired.
The polyolefins used herein non-exclusively include polymers of alpha-olefin monomers having from about 2 to about 6 carbon atoms and includes homopolymers, copolymers (including graft copolymers), and terpolymers of alpha-olefins. Illustrative homopolymer examples include ultra low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), or high density polyethylene (HDPE); polypropylene; polybutylene; polybutene-1; poly-3-methylbutene-1; poly-pentene-1; poly-4-methylpentene-1; polyisobutylene; and polyhexene.
Polyolefins such as polyethylenes are commonly differentiated based on the density which results from their numbers of chain branches per 1,000 carbon atoms in the polyethylene main chain in the molecular structure. Branches typically are C3-C8 olefins, and which are preferably butene, hexene or octene. For example, HDPE has very low numbers of short chain branches (less than 20 per 1,000 carbon atoms), resulting in a relatively high density, i.e. density ranges from about 0.94 gm/cc to about 0.97 gm/cc. LLDPE has more short chain branches, in the range of 20 to 60 per 1,000 carbon atoms with a density of about 0.91 to about 0.93 gm/cc. LDPE with a density of about 0.91 to about 0.93 gm/cc has long chain branches (20-40 per 1,000 carbon atoms) instead of short chain branches in LLDPE and HDPE. ULDPE has a higher concentration of short chain branches than LLDPE and HDPE, i.e. in the range of about 80 to about 250 per 1,000 carbon atoms and has a density of from about 0.88 to about 0.91 gm/cc. Of these, low density polyethylene is the most preferred. Illustrative copolymer and terpolymers include copolymers and terpolymers of alpha-olefins with other olefins such as ethylene-propylene copolymers; ethylene-butene copolymers; ethylene-pentene copolymers; ethylene-hexene copolymers; and ethylene-propylene-diene copolymers (EPDM). The term polyolefin as used herein also includes acrylonitrilebutadiene-styrene (ABS) polymers, copolymers with vinyl acetate, acrylates and methacrylates and the like. Preferred polyolefins are those prepared from alpha-olefins, most preferably ethylene polymers, copolymers, and terpolymers. The above polyolefins may be obtained by any known process. The polyolefin may have a weight average molecular weight of about 1,000 to about 1,000,000, and preferably about 10,000 to about 500,000. Preferred polyolefins are polyethylene, polypropylene, polybutylene and copolymers, and blends thereof. The most preferred polyolefin is polyethylene.
Polyesters are typically produced as a reaction product of a diol and a dicarboxylic acid. Suitable polyesters non-exclusively include those made from ethylene glycol and terephthalic acid, such as polyethylene terephthalate (PET), from ethylene glycol and naphthalene-2,6-dicarboxylic acid, such as polyethylene2,6-naphthalate (PEN), from 1,4-bishydroxymethyl-cyclohexane and terephthalic acid, such as poly-1,4-cyclohexanedimethylene terephthalate (PCDT), or from ethylene glycol, naphthalene-2,6-dicarboxylic acid and biphenyl-4,4xe2x80x2-dicarboxylic acid, such as polyethylene 2,6-naphthalate bibenzoate (PENBB). Preferred are polyesters which are composed of at least 90 mol %, more preferably at least 95 mol % of ethylene glycol and terephthalic acid units or of ethylene glycol and naphthalene-2,6-dicarboxylic acid units. The remaining monomer units are derived from other aliphatic, cycloaliphatic or aromatic diols and dicarboxylic acids. Of these the most preferred polyester is polyethylene terephthalate.
Examples of other suitable aliphatic diols are diethylene glycol, triethylene glycol, aliphatic glycols of the formula:
HOxe2x80x94(CH2)nxe2x80x94OH
where n is an integer from 3 to 6, such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol, or branched aliphatic glycols having up to 6 carbon atoms. Preferred cycloaliphatic diols include cyclohexanediols, particularly 1,4-cyclohexanediol. Examples of other suitable aromatic diols are those of the formula:
HOxe2x80x94C6H4xe2x80x94Xxe2x80x94C6H4xe2x80x94OH
where X is xe2x80x94CH2xe2x80x94, xe2x80x94C(CH3)2xe2x80x94, xe2x80x94C(CF3)2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94SO2xe2x80x94. Also suitable are bisphenols of the formula:
HOxe2x80x94C6H4xe2x80x94C6H4xe2x80x94OH.
Other preferred aromatic dicarboxylic acids are benzene dicarboxylic acids, naphthalene dicarboxylic acids, for example naphthalene-1,4- or 1,6-dicarboxylicacid, biphenyl-x,xxe2x80x2-dicarboxylic acids, for example biphenyl-4,4xe2x80x2-dicarboxylic acid, diphenylacetylene-x,xxe2x80x2-dicarboxylic acids such as diphenylacetylene-4,4xe2x80x2-dicarboxylic acid and stilbene-x,xxe2x80x2-dicarboxylic acids. Suitable cycloaliphatic dicarboxylic acids include cyclohexanedicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid. Suitable aliphaticdicarboxylic acids are the C3-C19-alkanedioic acids, having straight-chain or branched alkane groups.
The polyesters may be prepared by a trans-esterification process, the starting materials for which are dicarboxylic esters and diols, which are reacted using customary trans-esterification catalysts, such as salts of zinc, calcium, lithium, magnesium and manganese. The intermediates are then polycondensed in the presence of widely used polycondensation catalysts, such as antimonytrioxide or titanium salts. The preparation may be carried out just as successfully by a direct esterification process in the presence of polycondensation catalysts, starting directly from the dicarboxylic acids and the diols.
In a preferred embodiment of the invention, the polyester layer may further comprise a metallized polyester, an aluminum oxide coated polyester, a silicon oxide coated polyester, a polyvinylidene chloride coated polyester, or combinations thereof. Such are well known in the art. A xe2x80x9cmetallized polyesterxe2x80x9d is intended to mean a polyester having a thin layer of metal attached to its surface or having metal mixed together with the polyester to form part of the layer. Such metallized polyester may be metallized with any suitable metal, such as aluminum, although other metals may be employed (e.g., copper, nickel, etc).
The middle layer and the outer layer are attached together such that such that when the middle layer comprises a polyolefin, the outer layer comprises a polyester, and when the middle layer comprises a polyester, the outer layer comprises a polyolefin. Further each of the middle layer and the outer layer may be either oriented or unoriented. In the preferred embodiment of the invention, each of the middle layer and outer layer are oriented. In contrast, the inner nylon layer is an unoriented; that is, it is either a cast or blown film structure which is not subsequently subject to an orientation process.
Each of the inner, middle and outer layers may be attached together either by coextrusion or by lamination via an intermediate adhesive layer. Of these, it is preferred that each of the inner and middle layers are coextruded while the outer layer is attached by lamination via an intermediate adhesive layer or tie layer. Also, when the middle layer comprises a metal foil, it is preferred that the layer be laminated to either the inner or outer layer.
The adhesive layer may be applied directly onto the any of the inner, middle or outer layers by any appropriate means in the art, such as by coating. Any suitable adhesive may be employed. Such adhesives include polyurethanes, epoxies, polyesters, acrylics, anhydride modified polyolefin and blends thereof. Modified polyolefin compositions have at least one functional moiety, such as those selected from the group consisting of unsaturated polycarboxylic acids and anhydrides thereof. Such unsaturated carboxylic acid and anhydrides include maleic acid and anhydride, fumaric acid and anhydride, crotonic acid and anhydride, citraconic acid and anhydride, itaconic acid an anhydride and the like. The adhesive layer may also optionally comprise a colorant, an ultraviolet light absorber or both.
Each of the inner, middle and outer layers may optionally also include one or more conventional additives whose uses are well known to those skilled in the art. The use of such additives may be desirable in enhancing the processing of the compositions as well as improving the products formed therefrom.
Examples of such include oxidative and thermal stabilizers, lubricants, release agents, flame-retarding agents, oxidation inhibitors, oxidation scavengers, dyes, pigments and other coloring agents, ultraviolet light absorbers and stabilizers, organic or inorganic fillers including particulate and fibrous fillers, reinforcing agents, nucleators, plasticizers, as well as other conventional additives known to the art. Such may be used in amounts, for example, of up to about 10% by weight of the layer. Representative ultraviolet light stabilizers include various substituted resorcinols, salicylates, benzotriazole, benzophenones, and the like. Suitable lubricants and release agents include stearic acid, stearyl alcohol, and stearamides. Exemplary flame-retardants include organic halogenated compounds, including decabromodiphenyl ether and the like as well as inorganic compounds. Suitable coloring agents including dyes and pigments include cadmium sulfide, cadmium selenide, titanium dioxide, phthalocyanines, ultramarine blue, nigrosine, carbon black and the like. Representative oxidative and thermal stabilizers include the Period Table of Element""s Group I metal halides, such as sodium halides, potassium halides, lithium halides; as well as cuprous halides; and further, chlorides, bromides, iodides. Also, hindered phenols, hydroquinones, aromatic amines as well as substituted members of those above mentioned groups and combinations thereof. Exemplary plasticizers include lactams such as caprolactam and lauryl lactam, sulfonamides such as o,p-toluenesulfonamide and N-ethyl, N-butyl benylnesulfonamide, and combinations of any of the above, as well as other plasticizers known to the art.
As mentioned above, the layers may be attached together by coextrusion. For example, the polymeric material for the individual layers are fed into infeed hoppers of a like number of extruders, each extruder handling the material for one or more of the layers. The melted and plasticated streams from the individual extruders are fed into a single manifold co-extrusion die. While in the die, the layers are juxtaposed and combined, then emerge from the die as a single multiple layer film of polymeric material. After exiting the die, the film is cast onto a first controlled temperature casting roll, passes around the first roll, and then onto a second controlled temperature roll, which is normally cooler than the first roll. The controlled temperature rolls largely control the rate of cooling of the film after it exits the die. Additional rolls may be employed. In another method, the film forming apparatus may be one which is referred to in the art as a blown film apparatus and includes a multi-manifold circular die head for bubble blown film through which the plasticized film composition is forced and formed into a film bubble which may ultimately be collapsed and formed into a film. Processes of coextrusion to form film and sheet laminates are generally known. Typical coextrusion techniques are described in U.S. Pat. Nos. 5,139,878 and 4,677,017.
Alternatively the individual layers may first be formed as separate layers and then laminated together under heat and pressure with or without intermediate adhesive layers. Lamination techniques are well known in the art. Typically, laminating is done by positioning the individual layers on one another under conditions of sufficient heat and pressure to cause the layers to combine into a unitary film. Typically the inner, middle and outer layers, along with intermediate adhesive layers, are positioned on one another, and the combination is passed through the nip of a pair of heated laminating rollers by techniques well known in the art. Lamination heating may be done at temperatures ranging from about 120xc2x0 C. to about 175xc2x0 C., preferably from about 150xc2x0 C. to about 175xc2x0 C., at pressures ranging from about 5 psig (0.034 MPa) to about 100 psig (0.69 MPa), for from about 5 seconds to about 5 minutes, preferably from about 30 seconds to about 1 minute.
As discussed above, the middle and outer layers are preferably oriented prior to being attached together, unless the middle layer is a metal (e.g., aluminum) foil, which is not orientable. For the purposes of the present invention the term draw ratio is an indication of the increase in the dimension in the direction of draw. Preferably, in the present invention the polyolefin or polyester films are drawn to a draw ratio of from 1.5:1 to 5:1 uniaxially in at least one direction, i.e. its longitudinal direction, its transverse direction or biaxially in each of its longitudinal and transverse directions. Preferably, these films are biaxially oriented, either sequentially or simultaneously in both the machine and transverse directions, or merely being blown into a film structure. This results in dramatic improvements in clarity, strength and toughness properties. As mentioned above, the nylon film is unoriented.
Although each layer of the multilayer film structure may have a different thickness, the thickness of the inner nylon layer is from about 1 xcexcm to about 50 xcexcm, preferably from about 5 xcexcm to about 40 xcexcm, and more preferably from about 5 xcexcm to about 10 xcexcm. The thickness of the polyolefin layer is from about 1 xcexcm to about 25 xcexcm, preferably from about 5 xcexcm to about 15 xcexcm and more preferably from about 5 xcexcm to about 13 xcexcm. The thickness of the polyester layer is from about 1 xcexcm to about 65 xcexcm, preferably from about 5 xcexcm to about 50 xcexcm and more preferably from about 5 xcexcm to about 25 xcexcm. While such thicknesses are preferred, it is to be understood that other film thicknesses may be produced to satisfy a particular need and yet fall within the scope of the present invention.
The oxygen transmission rate (OTR) of the multilayered film of the invention may be determined via the procedure of ASTM D-3985. In the preferred embodiment, the multilayered film according to this invention has an OTR of about 0.1 cc/100 in2/day or less, preferably from about 0.085 cc/100 in2/day or less and more preferably from about 0.07 cc/100 in2/day or less at 65% relative humidity at 20xc2x0 C.
The multilayered film of the invention may be heat shrinkable, generally by an amount of from about 2% to about 30%, more preferably from about 10% to about 20% in its length, or its width or each of its length and width. The multilayered film may further have printed indicia on an aluminum foil middle layer. Since such printing is on an internal surface of the structure, it will not rub off when the surface is contacted.
The film preferably has a puncture resistance of at least about 1600 grams as measured by ASTM F 1306. Preferably the film has a haze of about 5% or less as measured by ASTM D1003.
The multilayered film is useful for forming a package capable of storing a product, such as an organic solvent or solvent-containing material, such as a solvent soaked into an absorbent fabric. Such solvents may non-exclusively include ketones such as acetone or methyl ethyl ketone, alcohols, or hydrocarbons such as toluene. The package is also appropriate for storage of a variety of other products, such as motor oil. The package comprises a casing which defines an inner compartment for holding the product, said casing comprising a pair of overlapping chemical barrier films, each of said chemical barrier films comprising in order from the inner part of the package to the outer part of the package: the inner nylon layer, the middle layer and the outer layer. The overlapping chemical barrier films are heat sealed together by directly attached portions of the inner nylon layers around a perimeter of the inner nylon layers. Alternately, the package may be formed from a single chemical barrier film wherein the film is folded at an edge and sealed to itself by directly attached portions of the inner nylon layer around at least a portion of perimeter of the inner nylon layer.
The following non-limiting examples serve to illustrate the invention.

Multilayer laminate for use in chemical barrier packaging

Abstract: The multilayer film comprises an inner layer comprising an unoriented nylon; a middle layer comprising either a polyolefin, a metal foil, or a polyester attached to a surface of the inner layer; and an outer layer comprising either a polyolefin or a polyester attached to a surface of the middle layer; such that when the middle layer comprises a polyolefin, the outer layer comprises a polyester, and when the middle layer comprises a polyester, the outer layer comprises a polyolefin.


A quick mounting nut (2) movable, at least partially, without being rotated, axially to a threaded bolt (1), with a springing wire clip (4) being located in a nut housing (5) with a continuous coaxial opening (6), with the wire clip (4) at least partially engaging in a bolt thread (3) and having two legs (8, 8xe2x80x2) which spring relative to one another, with the opening (6) having an inner cone (7) which narrows radially from an axial neutral position of the wire clip (4) and with the wire clip (4) being movable axially to a limited extent and contacting at least partially inside the inner cone (7) in its locking position.

1. Field of the Invention
The invention is directed to a quick mounting nut, formed preferably as a fastening system for mounting bolts threaded rods which hang down in installation rails.
2. Description of the Prior Art
A quick mounting nut generally has radial inner engagement means which engages in a positive-locking manner in the outer thread of a bolt and which permits a screwing movement along the thread as the sole degree of freedom of movement of the nut which is positioned on the bolt. The nut is secured by the static friction of the thread with the engagement means of the axially clamped nut.
According to DE19737262A1, a facade fastening arrangement for mounting C-shaped sections has a wire clip with two springing legs which snap into elongated undercut openings of an axial supporting element in a friction-locking manner and positively engages therein. Such a force locking, snap-in fastening is unsuitable for threads with sloping flanks.
According to DE347859, a wire clip which is constructed as a wing nut for manual assembly engages in the threads of a bolt on both sides.
According to EP0084280, a springing wire clip, which has two legs and is constructed as a wire nut, engages in the threads of a bolt with both radial legs in the manner of a coil.
According to U.S. Pat. No. 3,880,041, a springing fastening element, which is constructed as a nut, contains in its hollow interior a wire clip which is wound coaxially in the shape of a coil and which engages in the threads. Axial positioning without screwing movement is not possible with these nuts.
According to DE-43-07-645, the wire clip of a quick mounting nut engages only partially in the threads, so that the quick mounting nut can be positioned axially by axial pressure.
According to DE19831001, a quick mounting nut with a wire clip, which is wound coaxially in the shape of a coil, is constructed as a self-locking wing nut in the interior of a nut housing and enables axial positioning without screwing movement, is secured by a screwing movement, and can be unlocked by a loosening torque acting along the wire clip. The engagement in the threads, which takes place only in a frictionally locking manner, does not permits to secure the quick mounting nut so that it would be able to withstand a load.
In order to fasten pipelines in installation rails, special rail nuts associated with the installation rails are used as part of a fastening system and are provided with a metric thread. A threaded rod or bolt serves as a connection element between the pipe clamp and the rail nut as well as for height adjustment. The threaded rods, which are supplied by the meter, are cut to the required length for mounting. As a result of cutting burs are formed and must be removed by cutting before screwing the rod into the rail nut. The cutting and height adjustment are very time-consuming.
DE4403974 discloses quick mounting nuts, which can be positioned axially to the threaded rod without being subjected to screwing movement. For this purpose, the engagement means of the quick mounting nut, which are constructed as threaded sectors and engage in the thread of the threaded rod in a positive-locking manner, can swivel out axially in a springing manner. After a screwing movement effected for securing the quick mounting nut, the swiveled-in engagement means, which are fixed at a stop, engage in a positive-locking manner in the thread of the threaded rod.
Further, DE4243185 discloses special rail nuts which are arranged inside the installation rails and comprise a pressure plate which is pre-mounted by snapping in for mounting on installation rails that are fixed on the outside of installation rails by another nut.
It is the object of the invention to further develop a quick mounting nut which fastens in a positive-locking manner.
Another object of the present invention is a quickly mounted fastening system for mounting at installation rails.
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a detachable quick mounting nut, which is movable axially relative to a threaded bolt and which comprises a springing wire clip within a nut housing with a coaxial through-opening, which wire clip partially engages in at least one thread, essentially has an inner cone which narrows radially within this continuous coaxial opening from the axial neutral position of the wire clip. The wire clip, which is movable axially to a limited extent, can contact at least partially the inner cone. The wire clip has two legs which spring relative to one another. Each of the legs, which extend almost parallel to each other, partially engages in the thread of the threaded bolt in a slightly radially friction-locking manner within the radial plane, so that the wire clip is displaceable partially axially in the inner cone by screwing movements.
As a result of this external positive movement conveyed through the inner cone, a screw-like, positive-locking fastening of the quick mounting nut takes place, with the wire clip engaging in the thread of the threaded bolt.
It is further advantageous that the wire clip is supported so as to be movable axially in a limited manner within a nut housing forming a manual nut.
A further advantage consists in that the nut housing comprises two shells which are guided so as to be movable relative to one another along the wire clip. One of these shells, serving as unlocking means, is a cover shell forming a wedge which is directed radially inward and which, in a first position, can be guided between the free ends of the legs of the wire clip so as to spread the latter against their pretensioning, so that the quick mounting nut can be positioned axially without a screwing movement. In the second position, the wire clip which is axially offset due to the directed rotation of the quick mounting nut and makes contact within the coaxial inner cone causes a positive engagement with the thread, so that the quick mounting nut can be secured and also loosened by screwing movements. The quick mounting nut is constructed so as to be switchable between the first position and second position, so that the connection can be canceled again.
The shells which are movable relative to one another are advantageously connected with one another via snap-in means which, in a further advantageous manner, form a guide along the wire clip embedded on the inside.
A fastening sleeve is advantageously formed integral coaxially on the side of the nut housing forming the inner cone. By means of this fastening sleeve, the quick mounting nut can be connected in a coaxially rotatable manner with a pressure plate or a rail nut constructed for mounting at installation rails.
In another embodiment, a cover shell advantageously has a radially expandable, coaxial outer cone sleeve with a radial outer circumferentially extending annular groove for the middle part of the wire clip in which the latter can be secured axially without tension. The outer cone sleeve is slit axially and can accordingly expand radially in a springing manner when the threaded bolt is inserted through it. In addition, the cover shell has a switching element in the radial outer area as fastening means for locking. When the switching element makes axial contact when actuated, the wire clip, which is supported on one side in an axially offset manner within the nut housing and which is secured axially in the annular groove is displaceable axially out of the annular groove to a limited degree and, through its own radial tension, automatically slides axially along the outer cone sleeve and engages in the threads.
The cover shell, with the radially expandable coaxial outer cone sleeve as actuating means for locking, advantageously has at least one, advantageously two, oppositely arranged, radially projecting, axially springing projecting arms which have, in the radial outer area, an axial bearing pin for the wire clip which is oriented toward the wire clip. These projecting arms in turn advantageously form expanding springing locking protuberances with which the radial outer areas of the wire clip can be snapped in in an axially fastening manner inside the legs, so that by actuating one of the projecting arms, or advantageously both of them simultaneously, the wire clip which is accordingly tensioned axially can be displaced axially out of the annular groove to a limited extent and slides over the outer cone into the thread.
The cover shell advantageously forms the gripping surfaces of the wing nut vertical to the projecting arms which are oriented along the wire clip.
In an advantageous alternative embodiment, a quick mounting nut is constructed as a plug-in rail nut with a cover shell securely connectable with the pressure plate via two webs of the quick mounting nut.
The webs are advantageously secured to the cover shell via respective film hinges. The webs hold the quick mounting nut at a predetermined distance from the pressure plate and are originally folded up during production and for easier preassembly.
The webs advantageously swivel a hold-down device, which is formed integral therewith, axially over the base shell of the quick mounting nut and press it against the wire clip, which is integrated therebetween inside the quick mounting nut and which is flexible axially to a limited extent accompanied by a slight axial pretensioning. The axially pretensioned gap which occurs between the two shells makes it possible to compensate the mounting thickness of the installation rails with a usual tolerance of about 0.4 mm when the plug-in rail nuts are mounted.
The quick mounting nut advantageously has teeth on the surface oriented in the direction of the base plate. Therefore, the wire clip makes possible, in addition, a pretensioned engagement of the teeth of the quick mounting nut in the counter-toothing of the installation rails. The wire clip accordingly combines the above-mentioned fastening function at the threaded rod with the mounting function at the installation rails by applying an axial pretensioning.
With respect to its basic shape, the quick mounting nut advantageously has a width which is slightly smaller than the opening of the C-shaped installation rails, so that the quick mounting nut can be inserted through the opening in the installation rail, and a length which is somewhat smaller than the inner dimension of the installation rail, so that the quick mounting nut which is oriented transverse to the rail axis can be supported in an axial positive engagement and is freely movable along the installation rail, and two diagonally opposed axial edges which are rounded corresponding to the circle of diameter Yxe2x80x2 which can be inscribed in the installation rail. As a result, the quick mounting nut which is introduced along the rail axis can be rotated into the installation rail only by turning clockwise. The nut is essentially prism-shaped.
An alternative fastening system for mounting at installation rails is advantageously constructed with two quick mounting nuts, wherein a first quick mounting nut which is constructed as a rail nut can be inserted into a C-shaped installation rail so as to be fixedly connected with the base plate. A second quick mounting nut, which is connected via the threaded rod inserted coaxially into both quick mounting nuts and which is constructed as a locking nut and can be screwed in by rotation, can be secured by static friction to the facing plane partial surfaces of the base plate and can be loosened again via unlocking means.
The two legs of the wire clip advantageously have an inclination which corresponds to that of the threaded bolt in order to ensure a positive-locking connection between the outer contour of the threaded bolt and the wire clip.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.