MXPA99003421A - Method of forming improved loose fill packing material from recycled paper - Google Patents

Abstract

The present invention comprises an apparatus and method for producing a biodegradable, thin-walled packing chip (20) from an aqueous pulp of recycled newsprint by contacting the pulp with a mold (40) comprising:(a) a solid core (41) having substantially the shape of the article to be formed and having a minimal number of holes through which air may be evacuated and (b) an air permeable, stretchable fabric (60) which covers the exterior of the core. After forming the chip (20) on the fabric through application of a vacuum, the fabric is separated sufficiently from the solid surface to cause release of the chip from the fabric (60). The dried packing chip has enhanced packing qualities, is environmentally friendly and provides a significant new use for recycled newsprint.

Description

METHOD FOR FORMING FILLING PACKAGING MATERIAL. IMPROVED. FROM RECYCLED PAPER BACKGROUND OF THE INVENTION The present invention relates generally to loose packing materials or "packaging", as they are sometimes called, such as "chips" or "peanuts", and to the molds and methods for forming them. As its name suggests, "loose-fill" packaging materials are used to surround an article that is being shipped within a container or package to prevent movement of the article within the container and to prevent contact between the surface of the container and the container. article and the inside of the surfaces of the container. Stated simply, the loose packing material is intended to cushion the article or articles being shipped, against forces that may be applied to the outside of the container during shipment. The present invention provides a method for preparing an improved loose packing material. The suitability of any loose filling material is judged by certain functional characteristics. Among other things, the loose packing material must be strong and have structural integrity, while providing the necessary buffering properties. Should be of light weight and should not be introduced into one another or sediment. The total volume of loose packing should not decrease during shipment and / or storage of the article and container, despite vibration, shaking or other movements imparted to the container. The loose packing material should flow relatively freely and be free of static, qualities that increase the ability to dispense it into the container and around the article during packing. Obviously • any loose packing material should be as cheap as possible. In recent years, expanded plastic foam, primarily polystyrene, has often been used as a loose packing material. Although one is formed A variety of shapes that include, for example, hollow cups, plates and S shapes, are often referred to • "peanuts". These plastic peanuts exhibit certain convenient buffering properties. On the other hand, they also have certain highly undesirable qualities. The The main one, among them, is the fact that plastic peanuts are not easily recyclable and are not biodegradable and, therefore, are not friendly to the environment. Whether they come to rest in the neighbor's yard or in a public sanitary landfill, they do not deteriorate. They mess up the landscape and occupy unnecessary space in the landfill. Unless they are used again as packaging material, the Plastic peanuts from an unpacked container are virtually useless. Frequently plastic peanuts exhibit static build-up, which makes it cumbersome to work with them. Children and pets can eat plastic peanuts, which causes choking, suffocation, illness or death. The negative qualities of plastic peanuts have provided incentives to prepare packaging from natural materials, friendly to the environment. For example, efforts have been made to prepare loose packing from organic material, such as wood fibers bonded together with starch and other adhesives and formed to the appropriate configuration. This type of packaging is relatively expensive to manufacture; Manufacturers have charged an extra cost higher than the price of plastic peanuts. These materials have several other flaws, including the fact that products that contain significant amounts of starch can attract rodents or pests. Attempts have been made to make loose-fill packing from recycled paper, particularly recycled newspaper. The examples are described in U.S. Patent Nos. 4,997,091, to McCreu; 5,151,312, from Boeri; 5,230,943 from Pregont; 5,372,877 of Kannan eril and 5,382,325 of ards and coinventores. This latter patent is assigned to the same successor in title of the present invention. These materials They are manufactured by molding the individual pieces of loose packing material from recycled paper pulp and water. In general, the molding of the "pulp" of paper to products, as in egg packaging, has used processes such as forming in vacuum forming machine, rotary, as illustrated schematically in Figure 1. As seen in the 1, the cylinder 150 contains molds, such as 160, which extend outward from the periphery of the cylinder. Typically, each mold is made of a "screen", i.e., a metal mesh, which has the shape of the interior of the final molded article. The cylinder 150 rotates clockwise as the molds continuously proceed through various stages of the process. These steps are illustrated in positions A to H of Figure 1. Figure 1 is not drawn to scale and is only for comparative purposes. In position A, the mold 160 is immersed in the aqueous pulp of cellulose 175, in the pulp tray 170. Simultaneously vacuum is applied towards the interior of the mold, in the directions shown by the arrows 172 (using an equipment not illustrated) , to force the pulp of the pulp tray against the mesh of the mold. As the water is expelled through the screen, the pulp of cellulosic paper is trapped on the screen to form the molded article. However, the water passes through the sieve. Vacuum continues to be applied until the molded article has been formed to the proper thickness, in the interstices of the mold 160. When the cylinder advances in its revolution, the sieve containing the raw article of molded pulp is rotated out of the pulp tray 170. The additional water by inverting the mold in the position E. In the position G it is brought until it is adjacent to the press and to the transfer drum 180. The drum contains the molds 181, which fit with the mold 160 and conform the outer shape of the molded article . By movement of the drum 180 in a left-handed direction, the coupling mold is brought to the position (not shown) in which it makes contact with the partially molded pulp, thereby pressing the pulp against the sieve 160 to impart the configuration to the pulp. of the final article, and force the excess water out. The removal of excess water is important to minimize the drying energy requirements, which can be one of the most important costs in the production of the molded product. When the molding is completed, the press and the transfer drum are rotated in a clockwise direction to separate the two molds. When that rotation is started, a positive air puff (sometimes referred to as a "separation blow") is directed through the screen 160 (by means of equipment not shown) in the direction of the arrows 182, to separate the pulp from the mold 160. The vacuum then retains the resulting molded article, loosely in the cooperating mold 181, until the press and the transfer drum 180 reach a position in which the molded article is released to the conveyor 185. Then the molded article and the like are passed, by means of the conveyor, through a dryer 186, during a period of time sufficient to eliminate the remaining water and produce the final product. The cylinder 150 continues to rotate the mold 160 through the position H. In the position H the mold is brought until it is adjacent to the spray station 190, where it is placed in contact with water to clean it in preparation for the next molding step, in position A. While this procedure is used commercially, it is far from perfect, in many aspects. Among other things, it is impossible to continuously and reliably prepare small, thin-walled items, such as loose packing material, with this equipment. This is unfortunate, since the cellulose packing material is preferably made with the walls as thin as possible. This generally improves its qualities as packaging material. More importantly, thin-walled cellulose packing material completely biodegrades in a shorter period of time. The impossibility of the prior art processes of producing thin-walled cellulose packing material is caused, in part, by the fact that the intermediate pulp article, prepared on the screen, usually contains excess moisture. Excess moisture reduces the structural stability of the formed pulp article, making it impossible to produce a thin-walled article having sufficient structural integrity to be satisfactorily removed from the screen by conventional blowing techniques. Further, the pressing of the molds 160 and 181 (in the position G illustrated in FIG. 1) forces the molded article into the interstices of the screen 160. When the article has thin walls, the blowing step for subsequent stripping is difficult to remove. perform satisfactorily without breaking, tearing or cracking the article. While it may be possible to eliminate the pressing step in station G, the separation of the thin-walled, molded article from the screen would still be difficult. This is further complicated by the height at which said separation would occur, which would result in the destruction or mutilation of the moist pulp article, when it falls on the conveyor. When multiple articles are being molded simultaneously, separation is further complicated by the fact that pressure is lost in the positive release blow, as soon as one of the articles is removed from the screen. It is particularly difficult to continuously and reliably prepare a thin-walled item from recycled newspaper and other recycled papers. In general, newspaper has relatively short fibers which significantly reduce the physical resistance of molded articles, wet, during the intermediate steps of the procedure. It has now been found that thin-walled packaging paper chips can be prepared safely and efficiently using the process of the present invention. As used herein, the term "chip" is intended to mean an individual unit of loose packing material, or packaging. Unless stated otherwise, the use of this term is not intended to imply that the chip has any particular shape. Thin walled packing chips have improved biodegradability. Surprisingly, the thin walled packing chips of the present invention also have improved characteristics, important for functioning as a loose packing material.

OBJECTIVES OF THE INVENTION It is an object of the present invention to provide an efficient and effective method for molding articles (particularly loose, thin-walled packing chips) from paper pulp. It is another object of the invention to provide an improved mold for forming articles (in particular wood chips). loose, thin-walled packing) from paper pulp. Last but not least, the invention provides an improved packing chip, that is, a thin-walled chip, prepared from paper pulp, which has both improved biodegradability and improved qualities as a loose packing material. These and other objects and advantages of the present invention can be achieved using the methods, apparatus and articles described herein.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic elevational view showing the arrangement of equipment typically used in the prior art processes for molding articles from aqueous pulp of paper, such as the process used to mold egg packages. Figure 2 is a perspective view of a packaging chip incorporating the present invention. Figure 3 is a rear perspective view thereof. Figure 4 is a side elevational view thereof, the elevation of the other side being identical thereto. Figure 5 is a top plan view thereof.

Figure 6 is a bottom plan view thereof. < Figure 7 is a sectional view, taken substantially in the plane of line 7-7 of Figure 5. Figure 8 is a front perspective view of a mold embodying the present invention. Figure 9 is a rear perspective view thereof. Figure 10 is a top plan view of the same; being its other sides identical to this one. Figure 11 is a side elevational view thereof. Figure 12 is a bottom plan view thereof. Figure 13 is a sectional view, taken substantially following the plane of line 13-13 of Figure 10. Figure 14 is a sectional view, taken substantially following the plane of line 14-14 of Figure 20. Figure 11. Figure 15 is a front view of a complete mold of the present invention, showing the configuration of the mold parts supported by a mold frame. Figure 16 is a front view of the mold and the frame shown in Figure 15, illustrating the formation of a thin layer of cellulose pulp thereon.

Figure 17 is a front view of a mold incorporating the present invention, showing the mold parts in their respective positions, in which a molded pulp article is removed from the mold.

BRIEF DESCRIPTION OF THE INVENTION An efficient and effective method has now been invented to form a biodegradable article, thin-walled, from paper pulp. This is achieved by using an improved mold as described herein. The thin-walled packing chip produced by the process and with the mold of the present invention has improved biodegradability and has improved qualities, such as loose packing material. In particular, the present invention is incorporated into a mold comprising: a) a core having substantially solid surfaces, which substantially form the configuration of the article to be formed, and which have a minimum number of holes through which you can extract or force air; and b) a flexible fabric material, which covers the outside of the core. As used herein, the term "substantially the configuration of the article to be formed" means that the core of the mold has a surface with the general configuration that corresponds to the interior or exterior configuration of the molded article. Because the fabric material is on top of the solid surface, and the molded article is formed on the fabric, the molded article will not have the exact, identical configuration of the solid surface of the mold; but a surface (that is, internal or external) of the molded article and the surface of the core will have substantially the same configuration. As used herein, the term "minimum number of holes" refers to one or more holes in the solid surface of the core, adapted to effect the application of a partial vacuum through the fabric, to form a molded article of thickness relatively uniform on the fabric, but not so numerous as to allow a significant amount of waste water to accumulate on the side of the fabric opposite that on which the molded pulp article is formed. The use of a mold with a solid core, which has substantially the configuration of the article to be formed, and which has a minimum number of holes for air movement, reduces the amount of water that is retained inside the mold . In fact, with the molds of the present invention there is little space, if at all, for the water to be retained on the side of the fabric opposite to that on which the cellulose article is formed. This reduces the amount of water in the pulp article formed on the mold, thereby improving the structural integrity and reducing the amount of water that must be eliminated subsequently from the pulp, by drying. In addition, the use of a flexible fabric material on the exterior of the mold helps to enable the formation of a thin-walled article that can be satisfactorily removed from the mold without blowing air blow that causes the molded article to break, It will tear or crack. The problem of trying to form an article of thin f-0 walls from paper pulp has previously been faced in a totally different way. U.S. Patent No. 2,851,054 to Muller and co-inventors, attempts to solve the problem by a two-step molding process. Initially an article of walls is prepared thin ones on a conventional wire screen. The article is then removed from that mold and processed in a second mold, or "expression", which presses the article formed between the male and female members of the mold, thereby reducing the wall thickness of the article and ejecting by expression the excess of water. This is substantially the same procedure as shown in Figure 1. Obviously, said two-step molding process requires more equipment and is not practical for mass production of large quantities of small, irregularly shaped articles, such as chips of packaging. Actually, Muller's patent and co-inventors do not mention the use of the process to form loose packing material. The use of cloth on the conventional wire mesh screen has been previously suggested in German Patent Specification No. 891,791, Marguerat, as a method for molding paper pulp. However, the molding process shown there is still predicated on the use of a wire screen mold, with a hollow interior. This results in the accumulation of water in the mold, which makes the safe production of small, thin-walled articles from molded paper pulp impossible. There is no recognition that the procedure of this German patent could be used to produce such an article, particularly thin-walled, loose-walled packing material. Additionally, the method is not suitable for commercial applications, since repeated contact and movement of the fabric and the wire screen would result in rapid fabric failure.

DETAILED DESCRIPTION OF THE INVENTION AND THE MODALITY PREFERRED An efficient and effective method for forming a thin-walled, biodegradable packaging chip from a pulp of cellulose material has now been discovered. The present invention is incorporated in a chip of improved packaging and in an apparatus and a method of molding to manufacture it. The packing chip is a thin-walled packing chip, produced in a unique configuration, from pulp of cellulose material. In this process the pulp is contacted with a mold comprising a center or core having substantially solid surfaces, which substantially form the configuration of the packing chip to be formed, and which have a minimum number of holes, a through which air can be pulled out or forced, and a flexible fabric material that covers the outside of the solid surface of the mold. A partial vacuum is applied to cause the cellulose to be deposited from the pulp in a thin layer, in the configuration of the packing chip on the fabric. After an appropriate period of time the mold is removed from the pulp and the vacuum is completed. The fabric and core are then moved to move them far enough to cause the thin layer of cellulose pulp with the configuration of a packing chip to separate from the mold. The molded pulp article is then dried to form the final product. The fabric is then sprayed with high pressure water to remove any remaining fibers from the fabric before the next molding cycle. The process of the present invention can be used with any aqueous cellulose pulp known to those skilled in the art. In the preferred form of invention, recycled paper is used to form the pulp. Because the invention forms an ideal use for the beneficial recycling of newsprint, which is widely available and inexpensive, this material is the preferred starting material. However, any other of the many forms of recycled paper, alone or in combination, could be used. Since recycled newsprint consists of relatively short cellulose fibers, a preferred embodiment of the present invention utilizes a small amount of "white office" or "corrugated" "recycled paper" to provide longer fibers that facilitate the molding process. An illustrative composition comprises 85% newspaper fibers and 15% office white fibers Other starting materials or mixtures of starting materials that supply the necessary cellulose material can be used Cellulose pulp can be prepared using Any of the techniques familiar to those skilled in the art In a preferred embodiment of the invention, it has been found convenient to add a surfactant to improve the wetting of the paper It has also been found convenient to add a flocculant that produces cationic charges that favor The shorter newspaper fibers adhere to the longer ones, improving in that way the dispersion of the pulp in the water. Finally, it may also be convenient to add starch to help bind the fibers for molding purposes, in order to reduce the dust that could otherwise occur in the handling of thin-walled molded articles, and increase their physical strength. The use of the starch or any other additive, however, is not necessary to produce thin-walled molded articles, in accordance with the process of the present invention.

A. IMPROVED PACKAGING CHIP. OF THIN WALLS By means of the present invention it is possible to prepare thin-walled molded paper pulp articles. For example, packing chips having local wall thicknesses up to 0.79 mm, and an average or average wall thickness, less than that amount, can be prepared. A loose, individual packing packing chip embodying the present invention is illustrated in Figures 2-7. The chip is formed using the mold illustrated in Figures 8-17, which are described herein. The chip 20 comprises an elongated central body 21, of square section, and defining an open end 22 and a closed end 24. The body is formed by four lateral planes 25, which define a square end 22, open. The closed end 24 has a polyhedral or pyramidal configuration, comprising four inclined lateral planes 26, intersecting along the intersection 28 and converging at a closed apex 29. The ridges or protuberances 30 are formed at the intersection 28 of the adjacent planes 25. These protuberances have two important functions and have shown unexpectedly improved results. First, they reinforce the chip and increase the structural integrity that prevents crushing. Second, they prevent the polygonal end 24 of the chip from entering the open end 22 of another chip, thus preventing the introduction of the chips into each other. Both functions significantly improve the performance of the chip 20 as packaging material. The thin walled products of the present invention are especially suitable as loose packing material. Because they have thin walls, they biodegrade faster than other loose packing materials prepared from cellulose pulp. Surprisingly, the fact that they have thin walls does not counteract their properties as a loose packing material. As shown in the following example, the loose-walled, thin-walled packing material of the present invention satisfies all the requirements of the US Federal Specification PPP-C-1683A, in contrast to typical polystyrene packing peanuts. .

EXAMPLE Loose packing packing chips such as those described above were prepared from an aqueous pulp comprising approximately 85 percent newsprint and about 15% "office white". The chips were prepared to the cube configuration of 2.54 cm and with an approximate density of 17.61 g / liter, or approximately 30.73 chips per liter. The packing chips meet the standards of the US federal specification PPP-C-1683A, entitled "Shock absorbing materials, bulk expanded polystyrene, loose fill", which states standards for the following characteristics. "Sedimentation by vibration" measures the ability of the tested material to support a packed item and prevent it from sinking into the container due to vibrations encountered during shipping. A low percentage of displacement is equal to a high degree of protection, since items are less likely to migrate towards the walls and sides of the container, where damage could occur. "Volumetric density loaded" measures the density of the product under a normalized load. "Crisp compression" measures the tendency of the tested material to compress itself under weight, over time.

The higher the percentage of shrinkage by compression, the lower the buffer capacity of the material. "Compression Reset" measures the ability of the tested material to return to its original volume after a period of compression. The higher the compression reset percentage, the smaller the capacity of the material to return to the configuration to fill gaps and cushion the items. "Electrostatic Adhesion" measures the tendency of the tested material to experience static buildup in system lines, supply equipment and bags. "Flowability" measures the possibility that the tested material flows through a nozzle of a supply hopper into a container. The faster the flow rate, the faster the containers will be filled. Loose packing packing chips, prepared as described, were tested in accordance with US federal regulations. The results are shown in table I.

TABLE I Test Result Pass / fail Sedimentation by vibration (maximum displacement of no more than 30%) 13? Approves charged volumetric density (% compression under weight load) 1. 113 Crisp compression (maximum 10% by weight / 0.028 kg / cm2 of load 5% Approves (maximum 15% weight / 0.056 kg / cm2 load) 9% Approve (maximum 18% weight / 0.084 kg / cm2 load) 6% Approve Compression recovery (maximum 5% weight / 0.028 kg / cm2 load) 3% Approve TABLE I (continued) Test Result Pass / fail (maximum 10% weight / 0.056 kg / cm ^ load) 6% Approve (maximum 13% weight / 0.028 kg / cm2 load) 2% Approve Electrostatic adhesion (Must be non-static) Approves Flow capacity (at least 169.8 liters / min) Approves B.- IMPROVED MOLDING AND MOLDING PROCEDURE The parts of a mold 40 incorporating the principles of the present invention are illustrated in Figures 8-14. The method for using the mold to prepare the packing chips 20 is illustrated in Figures 14-17. The mold 40 comprises a core 41. In the particular case illustrated, the core has a rectangular body which is square cross-sectional and has substantially solid external side wall surfaces 42, having a shape and a configuration corresponding generally to the internal shape of the packing chip 20 to be formed. At an end 44, the core or center 41 defines surfaces or inwardly inclining planes 45, which intersect at intersecting lines 46 which, in turn, intersect at and define an apex 48. The mold additionally defines wedge-shaped external ribs 49, which project from, and which they extend along the intersecting lines 46. The outer edges 50 of the ribs 49 define planes corresponding to, and extending from the planes of the core wall surfaces 42. The ends 51 of the ribs extend outwardly from the apex 48 and define tapered or inclined end planes 52, which have a slope generally less than that of the planes of the end surfaces 45 in slope. Thus, the core of the mold 40 defines and corresponds substantially in shape to the internal configuration of the packing chip 20. The mold 40 is mounted on an upper plate 54 of a mold frame (not shown). The core 41 can be made of metal, for example, of aluminum or plastic or of any other material that is durable and can be easily formed to smooth surfaces. In addition to the core 41, the mold 40 comprises a flexible fabric 60 which cooperates with the core in the preparation and removal of a molded article as described herein. Because the fabric makes contact with the core of the mold, the surfaces of the core must be smooth to prevent undue friction on the fabric. The fabric 60 can be made of any natural or synthetic canvas or any textile material that satisfies certain basic requirements. First, the fabric must be permeable to water, but not to the fibers of the pulp. Thus, the application of the vacuum causes the water to be passed from the pulp through the fabric, leaving a deposit of pulp on the outer side. The fabric 60 must also be laterally permeable to air. This quality ensures that when a vacuum is applied through the core holes it is distributed laterally in all directions instead of just through the fabric, to the other side, adjacent to each of the holes. This ensures that pulp is uniformly deposited on the other side of the fabric. If the fabric does not have this quality, the pulp is selectively formed adjacent to the holes. Secondly, the fabric must be stretchable multidirectionally, that is, in both axes. Preferably it should have a stretch ratio of at least about 3: 1 between the extended state and relaxed state. This allows the fabric to be stretched to cover the mold and move to a relaxed or contracted position, to help release the wet article from the fabric. Third, the fabric should be relatively thin, since thicker fabrics tend to hang, which causes problems both in forming and separating a molded pulp article.

Finally, the fabric must comply with pragmatic considerations, such as being relatively cheap, durable and easy to work with. Few materials meet all the above requirements. The preferred material is a synthetic material known as spandex, brand Lycra > - or mixtures of nylon and spandex elastic polyamides. (Lycra < - is a registered trademark of DuPont, residing in New York, NY, E. U. A.). Of the materials designated as Lycra, Lycra D2600-17, obtainable from Darlington Mills, seems to be quite superior to others that have been tested by the inventors. This material is a mixture of 67 percent nylon and 33 percent Lycra, with a weight of 111.88 g / m2. One of the unexpected advantages of this particular material is that it effectively distributes the air laterally in all directions, thereby causing a uniform layer of pulp to be deposited on the fabric. The mold core also contains an air channel communicating with a vacuum source (not shown) to apply a partial vacuum during the formation of the cellulose pulp article. In use, the formed end of the mold 40, which includes the core 41 and the fabric covering 60, is immersed in an aqueous suspension of cellulose fiber. When applying suction through the passages of the mold, a chip 20 is formed on the external surface of the mold. For this purpose, the mold body 41 defines at its operating end an internal chamber 55, inside which a central passage 56 opens, which it extends axially through the body 41, from an external tubular sleeve 58 extending axially from the end 59 of the body opposite the apex 18. The sleeve 58, in turn, is connected to the vacuum source to apply suction to the inner chamber 55 of the mold. Suction from the mold chamber 55 is applied to the external area of the mold surfaces through transversely extending passages 56, which open to the outer side wall surfaces 42 of the mold core 41, and to transverse channels 58 , parallel, sunken into the sidewall surfaces 42 of the mold, adjacent to the opening of the passages 56. Suction is also applied to the outer surfaces of the apex end of the mold, through the apex passages 59, which extend from the chamber 55 and opening to the sunken area, defined between the projecting ribs 49 and the sloping end surfaces 45, as shown in Fig. 10. The mold also comprises a material 60 of flexible fabric that remains on top of it. the surface of the core 41 when the mold is in the position to form the packing chip, which is illustrated in Figure 16. The cloth sleeve 60 is fixed at one end to the core 41 m by means of a pin or a button 61, which is forcedly and securely inserted into an indentation or hole 62 at the apex of the core 41. The button 61 is made of a deformable material in such a way that it deforms by contact with the core, forming in that way a Secure fixation when it is forced into apex hole 62. Alternatively, the hardened metal button and the core of a softer material, such as a plastic, can be made. At its other end, the edge portion 64 of the fabric sleeve 60 is secured between the spacer plates 65, 66, which form a lower mounting plate assembly 68 of the mold frame. In the embodiment illustrated in the drawings, the top or top mounting plate 54 is fixed to the assembly 68. The spacer plates 65, 66 move relative to the static top plate 54. When the spacer plates 65, 66 are raised, the fabric sleeve 60 is stretched over the surfaces of the core 41, and covers the core so that it can be immersed in the pulp suspension of cellulose and a suction applied to form a chip on the mold 40 and the fabric 60. After forming a chip on the end of the mold 40, the separating plates are lowered to separate the cloth 60 from the surface of the core and effect the elimination of the article 20 of molded pulp. Alternatively, the upper mounting plate 54 can be movable and the separator plates 65, 66 can be fixed. When the mold is in the position shown in Figure 16, it can be brought into contact with the cellulose pulp. A partial vacuum is then applied through the entire channel and through the holes in the solid surfaces of the core, as previously described. This forces that the pulp is brought against the fabric, leaving a thin deposit of cellulose fibers 25 on the surface of the fabric, as shown in the figure. When the appropriate amount of cellulose has been deposited on the mold, the mold is removed from the pulp. The core fabric is then separated sufficiently to cause the molded article to be released from the mold, as shown in Figure 17. As previously described, the prior art processes for molding pulp typically used wire mesh molds. . When a partial vacuum was applied to the entire mold, cellulose pulp was deposited on the surface of the mold. Surprisingly, it has now been found that it is not necessary; Actually it is not convenient, use a mold with a series of holes distributed evenly over its entire surface. It has now been discovered that molded pulp articles having essentially uniform thicknesses can be prepared with molds of the present invention, such as the one illustrated in Figures 8-14. The core of the mold has a minimum number of openings for application of the vacuum. The Lycra fabric that lies above the core acts to uniformly distribute the vacuum over the surface area of the mold, thereby serving for the same purpose as the interstices in the metal sieve molds of the prior art, that is, to distribute uniformly vacuum along the surface of the mold.

However, the molds of the present invention do not have the deficiencies of the molds of the prior art. The pulp-forming molds of the present invention have a core having a substantially solid surface and a fabric covering. The core has two important properties. First, it has a "substantially solid surface", which means that the core is three-dimensional and, unlike a wire mesh, has a surface that is substantially continuous. The core itself may be hollow and, in fact, in the embodiment shown here, it has one or more channels to communicate the partial vacuum to the surface of the mold. However, the surfaces of the core, in themselves, are substantially uninterrupted. Secondly, the substantially solid surface of the core has a minimum number of holes, through which partial vacuum can be applied. Although it is not desired to be limited by any operating principle, it appears that the fabric remaining above the substantially solid surface helps to distribute the partial vacuum applied through the holes laterally and relatively uniformly along the surface of the mold. As described herein, a "minimum number of holes" means a sufficient number of holes to cooperate with the fabric to produce a molded article with a relatively uniform wall thickness, and less than the number of holes it would give for the retention of an excess of water in the mold results; interfering in that way with the formation of a thin walled molded article. The number of holes that may be appropriate for a particular mold depends on the shape of the mold, the nature of the fabric covering it, the nature of the pulp and the desired properties in the molded article to be formed. Because the molds of the present invention have a substantially solid surface, covered by cloth, a minimal amount of water, if at all, remains in contact with the fabric after the water is sucked into the mold. In contrast, the prior art molds retain the water in the hollow area within the wire mesh screen; that water can "come back" into the molded pulp article after the vacuum is relieved, thereby breaking or otherwise destroying the integrity of the wet, molded pulp article. In the present invention a core having substantially solid surfaces occupies the interior space behind the fabric covering on which the pulp is deposited, and prevents the water from being retained within that space and in contact with the fabric. As a result, the mold does not contain excess water, an important factor in the possibility of preparing a thin-walled pulp article. Obviously, the core could have additional holes above the minimum amount. However, the use of individual holes will result in fewer air flow rates, which will prevent the proper formation of a molded pulp article on the fabric. When a thin layer of cellulose pulp has been formed, of the appropriate configuration, on the fabric, the mold is removed from the pulp solution. With wire mesh molds of the prior art it was impossible to safely unclog a thin, moist layer of cellulose from the many interstices of the mold. In the present invention, the thin layer of cellulose pulp is removed from the mold at the end of the vacuum and separates the fabric from the solid surface of the mold, enough to release the molded article from the fabric. Molded pulp articles having an essentially uniform thickness can be prepared with molds incorporating the present invention, although the mold core has a minimum number of openings or holes for the application of the suction. The Lycra fabric that lies above the core acts to evenly distribute the vacuum over the surface area of the mold. The molds of the present invention are thus a surprising and substantial improvement over the prior art, and do not have the deficiencies of the prior art molds. Figure 16 illustrates a manner in which separation of the molded article is achieved. The separating plates are moved downward, thereby separating the fabric from the solid surface of the mold except at the apex of the mold, where they remain united. Although not illustrated in this figure, the molded pulp article is separated from the fabric and falls a short distance down, under and away from the separator plates. Normally, the entire mold and the mounting plates have been moved, that is, by moving the plate on which they are fixed, to a place away from the pulp bath, where the molded pulp article can be collected. Preferably this occurs by lateral movement, which reduces the height between the mold and the receiving surface, when the molded pulp article is released, from the mold. It should be understood that the molds of the present invention can be used individually or they can be assembled side by side in rows and columns, on rotating drums or on flat plates, to improve the efficiency in the production of multiple thin-walled articles. When flat plates are used, the plates of the pulp suspension will be lifted and moved laterally to a position in which the article is separated from the mold, thus minimizing the vertical fall to which it is to be subjected to the articles. Another advantage of the present invention is that molded pulp articles contain less water than thick-walled articles produced with mesh screen molds. As a result, less energy is required in the form of heat to dry the pulp to final products. Drying can be achieved using conventional procedures, such as forced air or convection ovens, known in the art. By means of the present invention it is possible to prepare thin walled molded paper pulp articles. For example, packing chips having wall thicknesses up to 0.79 mm and an average or average wall thickness that is amount can be prepared. It should be understood that numerous variations can be made to the present invention without departing from its principles. In particular, the solid mold may have other shapes and sizes than those illustrated in Figures 2 to 5. The configuration incorporated in those figures has been designed to achieve certain goals. Among other things, the resulting chips are formed in such a way that they are not introduced into each other. The configuration, in particular the corner protuberances, prevent the introduction of each other and increase the firmness of the thin-walled structure. However, it is contemplated that molds with other shapes and sizes may be used, within the spirit of the invention. For example, it is possible to use the methods of the present invention to form thin-walled packing chips, having cylindrical or pyramidal shapes, which are open at one end and which meet the qualities described in the examples that follow. The process of the present invention can be used to produce other articles of various configurations from paper pulp. It is particularly useful for forming thin-walled articles and for forming articles from recycled paper pulp. The description and examples given herein are intended to illustrate representative embodiments of the invention. The following claims are not intended to be limited to the specific embodiments described. The invention is susceptible of modifications, variations and changes, without departing from the appropriate scope or the just meaning of the following claims.

Claims (53)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for forming a biodegradable, thin-walled article, characterized in that it comprises: forming an aqueous pulp of cellulose; contacting the pulp with a mold comprising: a core having a substantially solid surface that has substantially the shape of the article to be formed, which has a number of holes in the surface, through which it can be extracted the air, and channels that connect each of the holes with a vacuum source for air extraction; and a stretchable, air permeable fabric that covers the outside of the solid surface of the mold; applying a vacuum through the holes in the surface of the core, thereby causing cellulose to be deposited from the pulp on the fabric, in a thin layer having the shape of the article; remove the mold from the pulp; and separating the fabric sufficiently from the solid surface of the mold, to cause the cellulose layer to separate from it.

2. The method according to claim 1, further characterized in that the thin-walled, biodegradable article is a loose packing material.

3. The method according to claim 2, further characterized in that the aqueous cellulose pulp comprises recycled paper.

4. - The method according to claim 2, further characterized in that the aqueous cellulose pulp comprises newspaper.

5. - The method according to claim 4, further characterized in that the aqueous cellulose pulp also comprises starch in an amount effective to minimize the dust associated with the handling of the thin-walled biodegradable article, and to increase the physical strength from the article.

6. The method according to claim 2, further characterized in that the stretchable, air permeable fabric is a material selected from the group consisting of spandex and nylon / spandex blends.

7. - The method according to claim 2, further characterized in that the stretchable, air permeable fabric is spandex.

8. - The method according to claim 2, further characterized in that the stretchable, air permeable fabric is a blend of approximately 67 percent nylon and about 33 percent spandex material, weighing approximately 111.88 g / m2.

9. The method according to claim 2, further characterized in that it comprises the additional step of drying the thin layer of cellulose extruded from the mold.

10. - A method for forming a thin-walled, biodegradable packaging chip, characterized in that comprising: forming an aqueous pulp of cellulose comprising recycled paper; contacting the pulp with a mold comprising: a core having a substantially solid surface that has substantially the shape of the article to be formed, which has a number of holes in the surface, through which it can be removed the air, and channels that connect each of the holes with a vacuum source for air extraction; and a stretchable, air permeable fabric material that covers the exterior of the solid surface of the mold; applying a vacuum to said mold, sufficient to cause cellulose of the pulp to be deposited on the fabric in a thin layer having the general shape of the packing chip; take out the mold from the pulp; Separate the fabric sufficiently from the solid surface of the mold, to cause the thin layer of cellulose to separate from it; and drying the thin cellulose layer to form the packing chip.

11. - The method of compliance with the claim 10, further characterized in that the recycled paper comprises newspaper.

12. The method in accordance with the claim 11, further characterized in that the aqueous cellulose pulp also comprises starch in an amount effective to minimize the dust associated with the handling of the biodegradable, thin-walled article, and to increase the physical strength of the article.

13. - The method according to claim 11, further characterized in that the stretchable, air permeable fabric is a material selected from the group consisting of spandex and nylon / spandex blends.

14. - The method according to claim 11, further characterized in that the stretchable, air permeable fabric is spandex.

15. - The method according to claim 11, further characterized in that the stretchable, air permeable fabric is a blend of approximately 67 percent nylon and about 33 percent spandex material, weighing approximately 111.88 g / m2.

16. - The method according to claim 11, further characterized in that the core further comprises a central body having a square cross section; one end of the body is open and the other end comprises four inclined sides, arranged in a pyramidal configuration.

17. - The method according to the claim 13, further characterized in that the core further comprises a central body having a square cross section; one end of the body being open and the other end comprises four inclined sides, arranged in a pyramidal configuration.

18. - The method of compliance with the claim 14, further characterized in that the core comprises additionally a central body having a square cross section; one end of the body being open and the other end comprises four inclined sides, arranged in a pyramidal configuration.

19. - The method according to claim 15, further characterized in that the core further comprises a central body having a square cross section; one end of the body being open and the other end comprises four inclined sides, arranged in a pyramidal configuration.

20. A thin-walled molded cellulose fiber packing chip characterized in that it comprises: a central body having a polygonal cross-section; one end of the body being open and the other end closed; said closed end is defined by a plurality of intersecting inclined sides arranged in a polyhedral configuration; and elongated protuberances extending along the intersections of the adjacent inclined sides.

21. The packaging chip according to claim 20, further characterized in that the body is square cross section and the closed end is pentahedral configuration.

22. The packing chip according to claim 20, further characterized in that the body is of Pentagonal cross section and the closed end has a hexahedral configuration.

23. - The packaging chip according to claim 20, further characterized in that the body has a triangular cross section and the closed end has a tetrahedral configuration.

24. - The packaging chip according to claim 20, further characterized in that the raised protuberances are on the outside of the packing chip and extend outwardly from it.

25. - The packaging chip according to claim 20, further characterized in that the cellulose fibers comprise a substantial portion of recycled paper fibers.

26. The packaging chip according to claim 25, further characterized in that the cellulose fibers comprise a substantial portion of recycled newspaper fibers.

27. The packaging chip according to claim 25, further characterized in that the maximum wall thickness is approximately 0.79 mm and the average wall thickness is less than 0.79 mm.

28. The packaging chip according to claim 26, further characterized in that the maximum wall thickness is approximately 0.79 mm and the average wall thickness is less than 0.79 mm.

29. - A thin-walled packing chip, made of molded cellulose, characterized in that it comprises: a central body having a square cross section; one end of the body being open and the other end comprising four inclined sides, arranged in a pyramidal configuration; and raised protuberances formed at the edges, wherein the adjacent inclined sides meet; the protuberances being configured to increase the structural integrity of the chip and to prevent a chip from being introduced into the open end of another chip of the same configuration.

30. The packaging chip according to claim 29, further characterized in that the raised protuberances are on the outside of the packing chip.

31. The packaging chip according to claim 30, further characterized in that the cellulose comprises a substantial portion of recycled paper.

32. - The packaging chip according to claim 31, further characterized in that the cellulose comprises a substantial portion of newsprint.

33. - The packaging chip according to claim 31, further characterized in that the maximum wall thickness is approximately 0.79 mm, and the average wall thickness is less than 0.79 mm.

34. The packaging chip according to claim 32, further characterized in that the maximum wall thickness is approximately 0.79 mm, and the average wall thickness is less than 0.79 mm.

35.- A mold suitable for use in the formation of a biodegradable, thin-walled article, made from an aqueous pulp of cellulose, characterized in that it comprises: a core having a solid surface substantially in the shape of the article that is it will form, and that has a minimum number of holes in its surface, through which air can be extracted; and a permeable, stretchable fabric that covers the outside of the solid surface of the mold.

36.- The mold in accordance with the claim 35, further characterized in that it comprises means for moving the fabric and the core, one with respect to the other, from a first position in which the fabric covers the core, during the formation of the thin-walled article, from the aqueous pulp of cellulose, to a second position in which the fabric is sufficiently separated from the core to cause separation of the thin-walled article.

37.- The mold in accordance with the claim 36, further characterized in that the stretchable, air permeable fabric is selected from the group consisting of Lycra and nylon / Lycra blends.

38. - The mold according to claim 36, further characterized in that the stretchable, air permeable fabric is Lycra.

39.- The mold according to claim 36, further characterized in that the stretchable, air permeable fabric is a mixture of about 67 percent nylon and about 33 percent Lycra, with an approximate weight of 111.88 g / m2.

40. The mold according to claim 36, further characterized in that the core further comprises a central body having a square section; one end of the body being open and the other end comprises four inclined sides, arranged in a pyramidal configuration.

41. - The mold according to claim 40, further characterized in that the stretchable, air permeable fabric is selected from the group consisting of Lycra and nylon / Lycra blends.

42. - The mold according to claim 40, further characterized in that the stretchable, air-permeable fabric is Lycra.

43. - The mold according to claim 40, further characterized in that the stretchable, air permeable fabric is a blend of about 67 percent nylon and about 33 percent Lycra, weighing approximately 111.88 g. / pr '

44. - The mold according to claim 40, further characterized in that the core is selected from a material selected from the group consisting of aluminum or plastic.

45.- A mold for use in the formation of a biodegradable article, thin-walled, from an aqueous suspension of cellulose pulp, characterized in that it comprises: a core that defines a solid outer surface, which has substantially the shape of the article which is to be formed, and a quantity of means defining openings in the outer surface, through which the air can be drawn; said core further comprising a central body portion; one end of which defines a polyhedral portion having inclined surfaces intersecting along its edges and at an apex; elongated protuberances extending outward from the polyhedron, along the edge; the core having means comprising a suction passage extending through the body portion and means defining a plurality of branched suction passages, extending transversely outwardly from the said suction passage, to the openings in the core surfaces; and a stretchable, air permeable fabric stocking covering the outer surface of the mold.

46. - The mold according to claim 45, further characterized in that the body portion has a square cross section and the polyhedral end is pentahedral.

47.- The mold in accordance with the claim 46, further characterized in that it further comprises ribs of elongated protuberances extending along the lines of intersection from the apex to the body portion.

48. - The mold in accordance with the claim 47, further characterized in that the protuberances are wedge-shaped and extend from a wide portion at the apex to a narrow portion at the body portion.

49. - The mold in accordance with the claim 45, further characterized in that it additionally comprises means for moving the fabric and core mean, one with respect to the other, from a first position in which the fabric average covers the core, and a second position in which the fabric average it is separated from the nucleus.

50. - The mold in accordance with the claim 49, further characterized in that the stocking has an open end and a closed end; and an attachment that secures the closed end of the media to the core.

51.- The mold in accordance with the claim 45, further characterized in that the stretchable, air permeable fabric is selected from the group of fabrics consisting of Lycra and nylon / Lycra blends.

52. - The mold according to claim 45, further characterized in that the stretchable, air-permeable fabric is Lycra. 53. - The mold according to claim 45, further characterized in that the stretchable, air-permeable fabric is a mixture of approximately 67 percent nylon and approximately 33 percent Lycra, with an approximate weight of 111.88 g / m2 .