US 2777480 A
Description (OCR text may contain errors)
Jan. 15, 1957 R LINDA METHOD OF PACKAGING WAX AND THE LIKE Filed April 18, 1955 m j r [I I a I I II I ll 4 2 \,O b @2 2 25 3 2 7W 8 w z w v a L 7 1 T v A m B w l 9 2 3 I ATTOR NEY 2,777,480 METHOD OF PACKAGING WAX AND THE LIKE Frank Raymond Linda, San Francisco, Calif. Application April is, 1955, Serial No. 502,022
6 Claims. cai n-11 I This invention relates in general to waxes, wax-like substances and asphaltic materials which are solid at ordinary room temperature, but which are readily melted by the application ofheat, and which again become solids when cooled.
The invention relates more particularly to natural waxes of mineral, vegetable or animal origin, as well as synthetic waxes such as fatty alcohols, fatty acids and the like, which are sold for commercial purposes and are generally marketed in the form of wrapped SOlld blocks or slabs of predetermined size and weight.
It has been customary in the marketing of micro- United- States Patent Patented Jan. 15, 1957 other final shipping container or wrapping, and thus produce packaged wax which can be palletized and readied for shipmentalmost immediately, making possible considerably lower packaging costs. I
These objects are achieved by reducing the wax to molten state by heating it to a temperature above its melting point but below its decomposition point; passing the molten wax through suitable cooling means; such as a heat exchanger, in a continuous flow; subjecting the waXto a flow-inducing pressure in the cooling means and also preferably under agitation, maintaining the Wax in is performed and the means employed in such performcrystalline wax, for example, to form the wax into slabs of desired size by melting the wax, then pouring it into molds to cool, and finally packaging the cooled and hardened slabs in paper wrappers or other containers. In the endeavor to simplify such packaging procedure, attempts have been made to pour the molten wax directly into containers of cellulosic material, such as flexible multiwall paper bags so that the packaging would be complete upon the cooling and solidifying of the wax. Such attempts have, in general, been unsuccessful for various reasons. For instance, the hot molten wax often bleeds through the bag, resulting in some loss and causing the package to present an unsightly appearance. The paper container or bag has to be sustained and maintained in proper shape until the wax cools and solidifies sufficiently to produce a permanent shape for the package; and a considerable amount of time, namely, from two to three days, is required for a relatively large mass of molten wax in a bag or similar receptacle to cool and harden sutfi-ciently to be in condition to retain a definite shape and permit the packaged wax to be stacked on a pallet board or conveyor.
Hence, even the pouring of the molten wax directly into the final paper container did not'result in speeding up the production process to any great extent and did not permit a practical production line method to be established. Also, in the case of waxes having a higher melting point than ordinary commercial-parafiin, and particularly in the case of asphalt, the pouring of the molten mass directly into supported flexible paper bags or other containers of cellulosic material entailed certain hazards for those handling such operation. I
An important object of this invention is toprovide an improved continuous packaging methodfor waxes and similar heat softenable products, normally solid at room temperature, which solidify upon cooling, which method will avoid the difliculties above indicated and be capable of accomplishment by production line methods, that is to say to provide a method which will permit streamlined, continuous packaging operation.
A more specific object of this invention is to provide a rapid and practical method of packaging waxes or the like materials which will permit the wax to be extruded or delivered in a supercooled fluid, plastic state, but at a temperature below its melting point, directly into a flexible paper bag, such as a conventional multiwall bag, or
ance will be briefly described with reference to the accompanying drawings, wherein:
Fig. 1 is a'more or less schematic elevational ,view illustrating a form of apparatus by which the wax, after havingbeen reduced to a molten state, is handled until it is delivered into the final container or Wrapper;
Fig.z2is a sectional elevation, drawn to a larger scale, of a preferred type of cooling means through which the wax is passed during the treatment; and
Fig.3 is a horizontal section taken in a plane indicated by line 3-3 of Fig. 2.
Referring to Fig. 1, the wax, after having been reduced to a molten state by the application of heat through any suitable means (not shown), is delivered into a tank or hopper indicated at 10; and, while the wax is maintained in a molten state, it is drawn from the discharging bottom of suchtank or hopper lit by a pump 11 and thence delivered under pressure, through the conduit 19 and control valve 30, to a closed cooling zone or means which is designated in general by the reference character 12. Tank 10 and conduit 19 are heated by any suitable means (not shown) to maintain the wax molten until it reaches the cooling means 12, so that the wax can flow readily.
In its course through the cooling means 12 which is continuously maintained full of wax, the wax is supercooled under pressure, that is to say, it is cooled down to :a temperature below its melting point without solidification occunring. The wax is kept in constant motion and under pressure while in the cooling means 12, and preferably is subjected to considerable agitation, so that the cooling will take place substantially uniformly throughout the mass of the wax in motion prior to the discharge ofthe wax from the cooling means. While the cooling of the wax tends to cause partial crystallization to occur while the wax is in the cooling means, the wax nevertheless is not permitted to solidify because the pressure applied thereto keeps it moving until it is discharged from the :cooling means in a supercooled state and in the form of a slush-like, plastic consistency.
From the cooling means 012, the wax is promptly discharged directly into the linal shipping container or wnapper, preferably into a mul-tiwall paper bag, indicated at :1-3, the discharge taking place through the tube or spout '26 controlled by the valve 27, the valve 27 also serving as a means to fix the back pressure on the wax in order that it may -be maintained under the desired pressure in the cooling means for supercooling the same. The condition of the wax as it is extruded from spout 26 and passes into the bag 13 is rope like, so that it can be roped or otherwise physically shaped and consequent-1y can be made to fill conveniently the bag, or other container, and also in an efiicient and practical manner with a minimum of voids.
Filling of, the bag, or other container, is donequ ickly, and the supercooled wax hardens rapidly at room tom 'perature with the result that soon after the bag or container is filled, the pack-aged wax will be sufficiently solid to permit stacking. of molten wax delivered into the supply tank or hopper 10, the entire packaging method can be performed as a production line procedure; and, depending upon the size or capacity of the cooling means, a plurality of final discharge spouts can be provided, if desired, so as to enable a plurality of bags to be filled simultaneously with the supercooled wax as it is extruded from the cooling means.
Figs. 2 and 3 illustrate a preferred type of cooling means employed for the cooling of the molten wax and which has been found to be very satisfactory in the carrying out of this invention. The particular cooling means illustrated is a heat transfer apparatus manufactured and sold by the Girdler Corporation of Louisville, Kentucky. This heat transfer apparatus 12 has an outer By having a continuous supply sheet metal cover 14, a wall of insulation 15, and an annular chamber 16 for the heat transfer or cooling medium, which annular chamber 16 has a bottom cooling medium inlet 17 and a top outlet 18 so that a continuous circulation of the cooling medium is maintained through the annular chamber. Water, or any other suitable cooling fluid, can be employed as the cooling medium. The heat exchanger also has a center cylindrical chamber 20 into which the molten Wax is continuously delivered and which is continuously maintained full of wax by pump I l. The wax passes into the chamber through the pipe 19.
A large shaft '21, the diameter of which is preferably greater than one-half the diameter of the chamber 20, is positioned co-axially within the chamber '20, and the shaft has reduced ends which are rotat-ably mounted in bearings located in the top and bottom of the housing and indicated at 22 and 23, respectively. One of the shaft ends, the upper end 24 of the sh-aft 21, as indicated in Fig. 2, extends beyond the housing and suitable drive means (not shown) is connected therewith to effect rapid rotation of shaft 21. I
A plurality of scraper blades 25 is attached to the shaft 21 by means of hinge arm-s 25A, the arms being of sufficient length to enable the blades 25 to bearagainst the Wall of the chamber 20. Thus, when the shaft 21 l is rapidly rotated, the outer edges of the blades 25 will be caused to bear against the wall of the chamber 20 by centrifugal force and act to scrape any particles of crystallize-d wax which might have a tendency to adhere to the chamber wall. The rapidly moving blades 25 keep the wax in a state of agitation as the wax moves around in the chamber 24 and moves downwardly in the annular space between the shaft 21 and the wall of the chamber 29, with the result that the crystallizing particles are well mixed and the entire mass of wax is reduced to substantially the same supercooled temperature before the wax is discharged from the bottom of the heat transfer apparatus.
The heat transfer apparatus 12 is provided with one or more outlets 'or discharge spouts 26, depending upon its size, the rate at which the wax is caused to pass therethrough, end the amount of cooling required to be performed. Discharge spout 26 is provided with the aforementioned control extrusion valve 27.
A .pair of temperature gauges 2'8 and 29 is located at the inlet and outlet ends of the heat transfer appanatus, respectively, in order to enable the'temperaturev of the wax, as it enters the apparatus in the molten state and as it leaves the apparatus in the supercooled state, to be observed, and thus serve as a guide in keeping the treatment of the wax uniform. Similarly temperature gauges 4 *17' and 18 indicate the temperature of the cooling medium for the heat transfer apparatus as it enters and leaves the apparatus, respectively.
It would be possible to dispense with the agitating means in the heat transfer apparatus, and to arrange the size of the chamber- 20 land the speed and pressure at which the Wax passes through the chamber, so that there would be little likelihood that any crystallizing particles wouldadhe're to the chamber wall and at the same time lprovidei'the necessary thorough intermixing of the wax particles and the cooling of the wax uniformly throughout its mass. However, it is preferable in the carrying out the method to subject the wax to agitation as well as pressure induced flow while it is in the heat transfer apparatus or other cooling means.
The following table is an example of the satisfactory employment of my invention in the commercial packaging of a parafiin wax and also in the packaging of a microcrystalline wax, the wax in each case being packaged in 'mu'ltiwall paper bags'in amounts of 25 pounds of wax per bag. The particular paraflin wax given as an example had a melting point of 140 F. and the particular microcrystalline wax selected had a melting point of 170 F. In both cases, the solid wax had been melted by heating to a temperature of 195 F. prior to its delivery into the tank or hopper ll). The particular apparatus employed had a single discharge spent 26. Shaft 21 had a diameter of 1% inches, and was rotated at R. P. M. The outer wall of chamber 20 had a 2 inch internal diameter, making the chamber /3 inch in width; and the chamber was 24 inches long.
Paraffin Mlcrocrrs- Wax tallinc Wax Melting point of wax" F F. Temperature of molten wax at start of 195 F 195 1 treatment. Temperature of the supercooled wax when 120 F 125 F.
delivered from heat transfer apparatus. Pressure to which wax was subjected in lbs. per 150 lbs. per
heat transfer apparatus. sq. in. sq. in. Temperature of coolant (water) passing 67 F 66.6" F.
into heat transfer apparatus. Temperature of coolant leaving heat trous- 73 F 72.2 F.
for apparatus. Quantity of coolant circulated r. l. Wax output 12;]1 lbs. per 12?1 lbs. per
r. r. Residence time of wax in heat transfer Gsoconds Slightly less apparatus. tho-1n 6 secon s.
0 produced no serious deformation of the block of wax packaged by the bag. The process was performed as a continuous and practical operation, and the wax was packaged for shipment within 15 minutes.
It was found that the bags, and thus the packaged blocks of wax, could bein any desired shape or dimension which would be most suitable for the end use for which the commercial packaged wax was desired. Due to the supercooled condition of the wax when deposited in the bags, there was no bleeding of the wax from the bags and the appearance of the bags from the outside was not 0 marred in any way as a result of the filling of the bags with the wax.
With respect to certain types of waxes, such as microcrystalline wax and beeswax, which remain quite tacky upon hardening, it is desirable to have the inner wall surface of the bag coated With a release coating in the form of a thin film, for the purpose of enabling easy and clean stripping of the wax from the bag when the packaged wax is to be used. Any suitable grease resistant coating may be employed for this purpose, such as cellulose acetate, polyvinylidene chloride (Saran), and copolymers of vinyl acetate and vinyl chloride (Vinylite) coatings. However, the release coating is not essential.
With the foregoing examples illustrating the packaging of a paraffin or microcrystalline wax under a specific set of conditions, it will be understood by those skilled in the art that the operating conditions of this invention may vary according to the type of a heat-so'ftenable material, normally solid at room temperature, which is to be packaged.
For instance, the temperature to which a given material is subjected to efiectuate its melting may vary from about 3 F. above its melting point to a value below its decomposition point. The selected temperature should be such, however, that a complete melting of the material will ocour and unnecessary overheating of the material will be avoided. For example, a satisfactory temperature range for melting a parafiin wax having melting point of 140 F. was between about 150 F. and about 215 F., and for melting a microcrystalline wax having a melting point of 170 F. such range was between about 173 F. and about 220 F. g
The temperature of the coolant should be adjusted according to the temperature of the molten material to be delivered to the cooling means, and the output of the supercooled material so that optimum operating conditions may be achieved. Generally speaking, the material processed through the cooling means should be cooled to as low a temperature below its melting point as is practicable for packaging with the material in a fluid but plastic condition when discharged from the cooling means.
The range of flow-inducing pressure to which a given material may be subjected may vary broadly from slightly above atmospheric to about 200 pounds per square inch. A preferred pressure range for paraflin wax is from about 160 to about 190 pounds per square inch, whereas for microcrystalline Wax it is from about 130 to 170 pounds per square inch.
When the agitation of the material during its processing through the cooling means of the particular type herein described is employed, a speed of rotation of the shaft 21 of from about 100 R. P. M. to about 300 R. P. M. will satisfactorily meet most conditions ordinarily encountered in commercial practice. However, higher or lower speeds of rotation may be employed to provide a suitable agitation of the material during the supercooling step.
The residence time of the material in the cooling means should be adjusted to minimum necessary for supercooling the molten material to a desired temperature. Generally speaking, the residence time may vary from 3 seconds to 30 seconds but this is not critical.
The time required for the supercooled material to solidify after it has been discharged into the shipping container is very short and, here again, will depend on o the temperature of the supercooled material at the point of its discharge from the cooling means. In general, for an efficient packaging operation, the material should solidify within a time from about to 20 minutes.
While the invention is described as used particularly for the packaging of parafiin and microcrystalline wax, the invention is not to be considered as limited to any particular waxes. Even wax-like or asphaltic materials which have a higher or lower melting point than these waxes can be packaged with this process, provided such materials are in a solid state at ordinary room temperature.
1. The method of packaging wax or the like material which comprises applying heat to the wax to melt the same, supercooling the molten wax in a cooling zone While simultaneously maintaining pressure induced flow of the wax through such zone so as to maintain it in fluid state below its melting point, and introducing such supercooled fluid wax into a container.
2. The method of packaging wax or the like material which comprises applying heat to wax to melt the same, continuously feeding the wax in molten condition into a cooling zone, continuously applying pressure to convey the wax through said zone to supercool the same so as to maintain it in fluid state below its melting point, continuously feeding the wax from said zone, and continuously packaging the wax in flexible containers of cellulosic material,
3. The method of claim 2 in which the wax is also continuously agitated while in said cooling zone.
4. The method of packaging fluid wax in a multiwall paper bag to effect rapid solidification of the wax in such bag at room temperature, which comprises prior to introduction of the wax into the bag supercooling the same in a cooling zone while simultaneously maintaining pressure induced flow of the wax through such zone so as to cause it to remain'in a fluid but plastic state below its melting point, and then introducing the thus supercooled wax into said bag.
5. The method of packaging fluid wax in a multiwall paper bag to efiect rapid solidification of the wax in such bag at room temperature, which comprises prior to introduction of the wax into the bag subjecting it to simultaneous flow-inducing pressure and agitation in a cooling zone to supercool the same and cause it to remain in a fluid but plastic state below its melting point, and then introducing the thus supercooled wax into said bag.
6. The method of packaging fluid wax to effect rapid solidification of the wax in a container which comprises prior to introduction of the Wax into the container passing it through a heat exchange zone in contact with cooled walls of such zone to thereby supercool said wax below its melting point, maintaining a continuous flow of said supercooled wax through the heat exchange zone by continuously scraping supercooled wax from said cooled walls while subjecting said wax to a flow inducing pressure simultaneously with said scraping and cooling, .and
- introducing the thus supercooled wax into said container.
References Cited in the file of this patent UNITED STATES PATENTS 284,226 Patterson Sept. 4, 1883 1,783,864 Vogt Dec. 2, 1930 2,053,314 Balyozian Sept. 8, 1936 OTHER REFERENCES Chemistry and Technology of Waxes, pages 241, 256, by Warth, published 1947, by Reinhold Publishing Corp.