MXPA98004026A - Molded panels with open cell grates molded integralme - Google Patents

Abstract

Panels (20) of tensioned skin are provided, which have internal grids (22) of open cells, molded of materials such as fibers, and methods and apparatuses for their production are disclosed. The invention uses a porous screen (10, 14), which has a plurality of elastomeric cushions (12) spaced apart. The fibers, dispersed in a fluid, are introduced into the apparatus and over and around the cushions. The pressure exerted therein expels the fluid through the screen (10, 14) and consolidates the fibers to form a panel (20). The cushions (12) are designed and constructed in such a way that the fiber mat placed under the cushions, compressed by the pressure (24), is consolidated, so that the finished panel includes an integrally molded flange (24). The height, configuration and / or spacing of the cushions in the present invention, advantageously, provide improved release of the mold and a greater resistance to compression fit, after repeated use. The cushions provide greater consistency and improved quality in the formation of rims on the panels

Description

MOLDED PANELS WITH INTEGRALLY MOLDED OPEN CELL GRATES Field of the Invention The present invention relates to panels with skins or stretched layers and to panel assemblies and, more particularly, to panels molded with tensioned skins, which contain internal open cell grids and to methods and apparatus for producing these panels, as well as than to mold elements useful in such production.

Background of the Invention Woods, soft and hard, have long been used as structural components in the construction industry, due to their convenient characteristics of strength, relatively low cost and ease of manufacture and work. As the cost of wood has increased, alternatives have been selected, such as hardboard, due to its lower cost. The hardboard usually consists of cellulose fibers, water and a binder, such as a latex, starch and formaldehyde. However, all these alternatives tend to suffer a depletion, low weight resistance ratio, or the use of solvents or binders not suitable in their manufacture or process.

For many years, corrugated fibreboards have served as a basic, lightweight material for packaging and other lightweight applications. The corrugated fiber board is made of a flat fiber board material. A single sheet is corrugated to form a medium core, or corrugated medium. This requires a separate operation. The adhesive is then applied to the nodes on either or both sides of the corrugated median core and then attached to one or two flat sheets, respectively. The configuration is maintained by the joints. However, the panels in the corrugated fibreboard are relatively weak and do not carry structural applications by themselves. It is also known to produce certain molded articles, such as containers ** for eggs, flower pots, baskets and the like. These products are made on rigid molds. The mold is often semi-porous and covered with screen material. A vacuum is applied to the back of the mold, causing a flow through the screen and mold, so the fibers form a uniform mat on the screen. This mat on this rigid mold is consolidated with a solid mold correspondingly configured in reverse, pressed against the mat on the forming mold. This consolidates the mat between the two corresponding molds. The direction of the consolidating force is perpendicular to the mat. However, such articles lack the resistance that would be useful as structured components. To increase the strength of the formed panels, it has previously been known to produce stretched skin panels for use as structural components. Such panels are considered advantageous due to their high weight-resistance ratio. However, the high manufacturing cost has limited the practical commercial form of such components to high-cost exotic applications. Previously, such panels were built in layers, in which a layer of skin was fixed to an internal grid, commonly referred to as a "honeycomb". These honeycombs are often made of flat sheets or strips of paper or paper-like materials, which are combined by means of spaced rubber zones. The assembly is pressed and the adhesive is allowed to cure. A second skin is often applied in a similar manner, and the whole is trimmed to the desired dimensions. Previous methods of forming tensioned skin structural panels are found in the patents of U. U.A., Nos. 4,702,870, 4,753,713, 5,196,238, 5,277,854 and 5,314,654.

More recently, the basic components of the stretched skin panels have been molded from various fiber materials. Two such components are then gummed together to form the complete panel. See, for example, the patent of E. U. A., No. 4702,870. Panels constructed in this way provide advantages over the prior art, that is, a number of rubberizing and other manufacturing steps are avoided, and the greater production flexibility of many different kinds of open cell grids is avoided. However, the finished panels, produced according to the prior art, generally require at least one step of gumming and the inherent manipulations, adding this to the cost. Likewise, the available surface area, which is to be used as the contact area for the rubber, is generally smaller, since minor misalignments between the two layers would substantially loosen the strength of the rubber bonds. This prior art also incorporates fundamental limitations in the production of such panels and in the panels thus produced. The mold inserts used in the prior art to form the internal grid undergo compression adjustments, whereby repeated use changes the configuration of the inserts. This leads to: a) poor formation of the grid, which produce weaker and more inconsistent products; b) interference with the panel of the product in the mold, producing a poor release and possible damage to the product and requiring the use of mold release agents and labor, which increases costs and also decreases the quality of the product; c) increased production time, thus increasing costs and severely limiting the ability of such products to compete with other less expensive materials; and d) limitations on the raw material that could be useful. In the present invention, it has been discovered that new configurations and arrangements of the mold insert avoid these disadvantages and produce upper panels, under production techniques that result in such panels competing with a wide range of current products.

SUMMARY OF THE INVENTION The present invention provides the production of molded, stretched skin structural panels containing internal open cell grids in a highly advantageous and inexpensive manner. Thus, in a preferred embodiment of the invention the stretched skin fiber panels are provided, which increase the surface area used to form a rubber contact area between the layered panels and the panel assemblies. In another embodiment of the invention, stretched skin fiber panels are provided, which can be manufactured in a single step to include a second skin covering a substantial portion of the internal grid of open cells. In the invention, the panel material, preferably of fibers, is dispersed in a fluid and is introduced into a mold, comprising a bottom screen or porous carrier, on top of which a plurality of resilient mold inserts are mounted. The inserts are of such resilience, configuration and spacing that the pressure applied to the inserts causes them to flatten and trap the material / fluid mixture and, at least partially, under them. The pressure applied to the material / fluid mixture consolidates the material in these areas and expels the fluid through the screen or carrier. This apparatus and process produces open cells having ribs that are formed between the mold inserts and ridges integrally molded to and through the ribs, which are formed under and adjacent to the flattened mold inserts. The present invention provides improvements over the prior art, including: 1) improved lifting during the removal of the panel molds; 2) reduced surface area for adhesion to the upper part of the mold to the panel, during the removal of the panel; 3) greatly reduced cases of damage to the flanges and / or cushions, during the removal of the panel from the carrier; 4) improved resistance to the compression "fit", which occurs in the elastomeric material, after repeated use during the manufacture of the panel, and / or 5) increased production of ribs and ridges leading to stronger panels. The general effects are greatly increased efficiency in the manufacture of molded fiber panels, skin tensioned, and the reduction of materials and labor costs. In addition, the need for mold release agents is reduced, whereby it is advantageous to the environment and further reduces material costs. The panels of this invention can advantageously be made of cellulose material, such as wood fibers, paper and recycled wood products, and the like. The fibers may be of non-cellulosic materials, including fibers of animal origin, such as wood, or textile fibers, such as cotton, or synthetic fibers, such as various plastics and glass fibers, as well as mineral fibers, such as like rock wool and the like. Examples of agricultural fibers include hemp, and rice straw and wheat. Agricultural waste materials, such as palm leaves are yet another possible source of fibers. Other materials that can be dispersed in the fluid, preferably liquid, can be used, such as cement, mortar, and gypsum. Thus, in one aspect of the present invention, resilient mold inserts or cushions are provided which serve not only to establish the initial configuration of the grid, but also to determine its consolidation. These cushions are of a predetermined size and configuration and are located in a predetermined relation to each other on the carrier. The way to select the size and spacing of these cushions on the carrier determines the nature of the finished product, as it will appear from the following detailed specification. The cushions are of configuration, size and preferably uniform arrangement in the carrier, to thus produce panels with uniform and repeated belts. An important relation of the present invention is between the deposition of those cushions and the distance between them. It has been found that this relationship contributes to the advantages described above, and in particular to the improved formation of ribs and ridges. Preferably, the ratio of the height of the cushions above the carrier to the distance between them is from 0.15 to 0.5, more preferably from 0.2 to 0.4.

In the arrangement of the cushions on the carrier, an increased spacing is provided, so that the rate of emptying and the rate of passage of the water vapor are improved. In addition, the spacing in the present invention allows longer fibers to be deposited between the cushions, thus increasing the types of raw materials that can be used. This includes the use of high quality long fiber raw materials, and also the use of less expensive raw material processes and the pulp formation of virgin and recycled fibers. The resulting ridges and ribs in the panels of the present invention are thicker and more consistent, and have greater resistance to crushing and cutting resistance, and also provide superior bonding areas for lamination of the panel or the like. The present elastomeric cushions preferably have a ratio of height to base width of at least 0.85, more preferably between 0.85 and 2.0, such as between 0.9 and 1.8 and more preferably around 0.95 and 1.5. In these values, the height is measured as the height actually available for molding (i.e., above the carrier) and in an uncompressed or relaxed state. The base width, measured under similar conditions, is the largest dimension adjacent to the bottom of the cushion, above the carrier.

In another aspect of the present invention, the elastomeric cushions are provided with upright side surfaces, which are substantially concave. In a preferred embodiment, the cushions are tapered with the sides that are biangular, ie with sides that rise at an angle to their longitudinal axis and between them, greater taper angle. In a particularly preferred embodiment, a lower portion of each cushion forms an angle measured normal to the base of the cushion, which is about 15 degrees, and an upper portion of the cushion forms an angle of about 8 degrees. Various configurations in cross section, taken parallel to the bottom of the cushion, or carrier, can be used, which include the hexagonal, round, oval, square or rib type. Modes of this invention provide porous carriers or screens carrying a plurality of the above elastomeric cushions, as well as an apparatus and process for producing the panels using such cushions. In still another aspect, the present invention supplies molded panels having on one side a substantially continuous skin, molded integrally with a grid, comprising a plurality of open cells, defined by a plurality of ribs, having their thicknesses parallel to the plane of the grid and its heights define the thickness of this grid. On the side opposite the integrally molded grid, the panels have integrally molded flanges, which extend over at least a portion of the surface area of each grid cell and are substantially parallel to the skin of the panel. Thus, in a cross-section through the skin of the panel, rib and flange, this rib and flange together form a generally "T" -shaped member, integrally molded with, and extending outwardly from, the panel skin. or expensive. The hanging ratio of the flange from the rib portion to the width of the flange is an important feature of the present invention and is preferably at least 0.1, more preferably 0.3 to 0.4. In another aspect, the present invention produces panels of a monolithic, one-piece character having skin layers stretched on both sides of the open cell grid. The panels are thus formed according to the invention in the final form and, therefore, do not require any additional assembly and / or inherent handling. In this aspect, the integrally molded rims form a second tensioned skin fiber member, wherein this second member extends over a substantial portion of the surface area of each cell of the grid.

In yet another aspect, the present invention provides an apparatus for manufacturing such molded panels of tensioned skin, preferably fiber panels, The apparatus preferably includes a porous carrier, having a plurality of elastomeric cushions located there, each of these cushions having a predetermined spacing, size and / or configuration, as described above and will be described in more detail below, in order to consolidate the fiber mat under the cushion when the cushion is compressed. The apparatus further comprises a press for consolidating the fiber, deposited on the carrier that covers and fills the spaces between and above the cushions, in both normal and parallel directions of the carrier, by applying normal pressure to the carrier on the cushions at its remote ends of the carrier. carrier. The cushions are thus caused to expand parallel to the carrier and comprise the fibers placed there between them, as well as to consolidate the fibers placed above and below the cushions. A further aspect of the invention provides a method for producing molded panels of tensioned skin, which uses the apparatus described herein and in which a carrier fluid is used to contain the panel material. This carrier fluid moves through the apparatus, depositing material between and above the resilient cushions. After the material is deposited, the resulting grid is consolidated by the application of pressure to the tops of the cushions. As this pressure is applied, the cushions are compressed in the direction of the applied force, but they also expand at right angles there, thus reducing the spaces between the cushions, where the material is located. These cushions are also designed to consolidate the material mat in the space close to the carrier in the compression of the cushion. Thus, the material deposited between the cushions is consolidated both vertically and horizontally in an open cell grid, the material above the cushions. The cushions are compacted to form a first molded skin integral with the grid, and the material in the region surrounding the base of the compressed plates is compacted to form a flange molded integrally with the grid, covering at least a portion of the area. surface of each cell. Advantages and further applications will become apparent to those skilled in the art from the following detailed description of preferred embodiments and reference drawings, however the invention is not limited to any particular embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view, illustrating a carrier and a series of elastomeric cushions, according to the invention; Figure 2 is a side elevational view, illustrating the reservoir of the carrier liquid containing fibers, over the apparatus of Figure 1 and the release of a portion of the carrier liquid through the porous carrier; Figure 3 is a side elevation view, illustrating the use of an upper mold for applying pressure to the mat of elastomeric fibers and cushions, in a direction normal to the wearer, and the release of a portion of the carrier liquid through the carrier porous and the upper mold; Figure 4 is a side elevational view illustrating the increase in pressure applied by the upper mold to the mat of elastomeric fibers and cushions and the formation of ridges in the regions surrounding the cushion bases; Figure 5 is a side elevational view illustrating the release of the pressure applied by the upper mold to the fiber mat and the elastomeric cushions, - Figure 6 is a side elevational view, illustrating a panel formed in accordance with the invention; Figure 6A is a detailed view of a ridge and rib formed in accordance with the invention; Figure 7 is a bottom plan view of the panel of Figure 6, illustrating the ridges extending over a portion of the surface area of each of the open cells in the panel grid; Figure 8 is a side elevational view illustrating an alternative embodiment of an apparatus of the invention, comprising a carrier, air supply tubes and an inflatable membrane.; Figure 9 is a side elevational view of two subpanels joined together; Figure 10 is a side elevational view of a mode of a cushion seen above the carrier; Figure HA is a side elevational view of a preferred embodiment of a cushion, seen above the carrier, and Figures 11B-11C are top plan views of various embodiments of the cushion; and Figure 12A is a side elevational view of another preferred embodiment of a cushion, seen above the carrier, and Figures 12B-12D are top plan views of various embodiments of the cushion.

Detailed Description of Preferred Modes The invention will be better understood with reference to the accompanying drawings, which form a part therein and in that: Generally, in panels of the type of this invention and panels of the prior art, there are industry standards for the dimensions. A panel that is formed in the present invention can be used as a subpanel in a panel assembly, and joined to another subpanel to form a panel of standard thickness. Industry standards for plywood and particle boards include thicknesses of 12.7, 15.875, 19.05 and 31.75 mm. Thus, in the following detailed description, the specific dimensions relate to a panel of standard thickness. Specifically, such dimensions relate to the formation and / or sizes of a panel, which is nominally 9,525 mm thick and which when joined to a similar panel produces a product having a nominal thickness of 19.05 mm. In the present panels, the thicknesses of the skin, that is to say, thicknesses of faces, up to approximately 3,175 mm are preferred, with 1016 to 1651 mm being more preferred. Figure 1 illustrates an embodiment of the present invention that uses a porous carrier 10, which may be in the form of a screen, a band, a wheel, a roller, or the like, and which is generally made of metal, plastic or other materials capable of withstanding the pressures generated during the present method. This porous carrier can be stationary, for the production of the batch-like process of the present honeycombs, or it can be a mobile member, thus forming a part of a continuous production process. A wire mesh, such as a stainless steel or bronze screen, can be used, for example. Such wire meshes are typically used in the manufacture of paper and cardboard, or non-flange products. However, it has been found that a metal screen having large holes, which are traditionally used by the paper and paperboard industries, is preferred for the fastest casting time in the present invention. In addition, such a screen does not tend to stretch outward with use, in the degree of wire mesh screens. Preferably, a steel wire screen is used as the carrier 10. The holes in the carrier 10 must be large enough to empty the carrier fluid quickly, without emptying the fibers as well. Fixed properly to the porous carrier 10, are the elastomeric cushions 12, which will define, by their geometry and spaces between them, the configuration of the grid in the structural panels that are to be produced, according to the invention. The pads 12 will generally be evenly distributed across the surface of the carrier 10, more usually in a geometric pattern. The cushions can be attached to the carrier by the use of SILASTIC adhesive 736, from Dow Corning, Michigan, for example, by molding or any other mechanical method known to those skilled in the art. Preferably, the ratio of the weight of the cushions above the carrier to the distance between them is from 0.15 to 0.5, more preferably from 0.2 to 0.4. The cushions are spaced more than 1.27 mm apart from the carrier. Preferably, in a 9,525 mm thick panel, the spacing of about 1524 to 5.08 mm and, more preferably from 3,302 to 4,572 mm, between the cushions can be used, although the spacing can vary according to the carrier used and the desired panel characteristics. More preferably, a spacing of about 4572 mm is used between the cushions. The increased spacing between the cushions allows the use of longer, high quality fibers to form the quality panels without prolonging the emptying times during manufacturing. The present cushions can be formed of any sufficiently elastomeric material, capable of resisting heat, steam and pressure in the panel molding process, in prolonged cycles of use. In addition, the elastomeric material should not stick to the pressed panel, so as to prevent the release of the panel and / or damage to the cushions. Silicone rubber, such as SILASTIC HS, from Dow Corning, has been found particularly useful in this regard. Although synthetic or natural rubbers, such as other silicone rubbers, styrene-butadiene elastomers, or isoprene, having the aforementioned performance characteristics, can alternatively be used for the cushions. Other resources for providing the features of the present invention include the elastomeric cushion durometer classification, where a softer, more foldable cushion is expected to increase the amount of the fiber mat that is consolidated during the press stage in the area that surrounds the base of each cushion. The chosen classification must provide a sufficiently high cut resistance under tension-compression load cycles, which occur during the manufacture of the panels. Preferably, the Shore A hardness will be from about 15 to 45, more preferably from 20 to 35. Especially preferred, the Shore A hardness of the cushion is about 27. It should be noted that the preferred classification of the durometer is dependent, inter alia, on of the fibers used in the panel, since the use of a too hard cushion will tend to create ridges that will detach from the panel rib during the removal of the panel from the carrier. In a preferred embodiment of the invention, the elastomeric cushions are hexagonal in cross section, so that they will form hexagonal cells in the grid of the panels. It will be readily apparent that numerous other geometrical shapes can be employed in the creation of the elastomeric cushions, the selection of which will determine the shape of the cells contained in the present grids. Although, it has been noted that some other pad configurations can form substantially hexagonal cells as well, due to the narrow arrangement of the pads in the carrier. Referring to Figure 1, a ratio of the nominal dimension or diameter of the bottom of the cushion, b, to the dimension or diameter of the upper part t, ie b / t, is preferably 1.0 to 1.7, more preferably 1.1. to 1.7 and especially preferred of around 1.4. Referring to Figure 7, the present elastomeric cushions serve not only to establish the initial configuration of the grid, but also to determine its consolidation and integration with the commonly formed taut skins and ridges. The cushions are of a predetermined size and configuration and are located in a predetermined relation to each other in the carrier. The way to select the size, configuration and spacing of these cushions in the carrier determines much of the nature of the finished product. For example, in the formation of the panels of the present invention, the cushions will typically be spaced more widely than the cushions in the prior art to form a panel of comparable overall dimensions. In the present invention, the higher cushions are capable of maintaining comparable thicknesses and grid heights formed in the panel, while providing greater densification of the fibers as well as wider flanges. As shown in Figure 1, a preferred embodiment of a cushion in the present invention comprises an upper surface, which is substantially parallel to the carrier 10, a body portion and a base portion. In the cross section shown, the upper part of the cushion has a height h, measured from the carrier, which is at least 85% of the width b of the base of the cushion. In general, the dimension or width t of the upper part of the cushion will be smaller than the dimension of the base b. Preferably, the ratio of the height to the width of the base, h / b is about 0.85-2.00 (85 to 200 percent) more preferably is about 0.90-1.90 (90 to 180 percent) and especially preferred of around 1.00-1.50 (100 to 150 percent). Referring to Figures 10, 11A-11C and 12A-12D, preferred configurations of the cushion of the present invention comprise substantially concave sides, in which Figure 10 may have a round or square cross section (not shown) taken in a plane parallel to the carrier. Figures 11A-11C and 12A-12D illustrate possible configurations of a cushion having a "biangular" configuration of the present invention, in which the general curvature is defined by two substantially linear sections forming two angles, which are measured relative to each other. to the longitudinal axis of the cushion. A lower side surface of a biangular cushion forms a first angle a and an upper side surface of the biangular cushion forms a second angle β. The first angle a is generally greater than the second angle ß. Preferably a is about 15 degrees and β is about 6 degrees. In one embodiment of the present invention, the present cushions are of sufficient height and elasticity so that, when normal pressure is applied to the carrier, the fiber material around the base of the cushion, where it is fixed to the carrier, will be compressed and will consolidate against the carrier. This occurs because the fixation of the cushion to the carrier reduces its local capacity for expansion in a direction parallel to the surface of the carrier. The resulting pressure traps and consolidates a portion of the fiber mat surrounding the base of the cushion. Depending on the height, the cross-sectional area and the elasticity of the cushion, this portion of the fiber mat can form a flange member molded integrally with the ribs of the open cell grid and parallel to the carrier. These ridges may be relatively narrow, covering only a small portion of the surface area of the open cell grid, for example greater than 0%, preferably greater than about 5% and up to about 40% of the cell surface area. One can obtain many benefits from the flange when it covers approximately 5 to 15% of the surface area of the cell. Such a flange will strengthen the grid, increase the rigidity of the panel and supply n contact area when it is desired to adhere two panels together to form a multi-layered, tensioned skin fiber panel. At the other end, the integrally molded flange can be extended to cover a substantial portion of the surface area of the cell formed in the grid by the compressed cushion, thereby forming a second skin tensioned integral with the grid in the present panels. The amount of the surface area of the cell covered by this flange, or the second "skin", can vary widely, for example from at least 10% of the surface area and up to 90%, preferably from 15 to 40%, and more preferably from 15 to 20% of the surface area. The practical limits of the amount of surface area that can be covered are dictated to a greater degree by the base area of the elastomeric cushion 12, which is fixed to the carrier 10. One can obtain the benefits of these flange embodiments, or second skin tense, when the flange covers approximately 15% of the surface area of the cell. However, larger hanging ridges, of about 25 to 40%, are preferred. For a panel of approximately 9,525 mm thickness, the flanges preferably have widths of at least 1524 mm, preferably between 2032 and 5.08 mm, more preferably between 3,302 and 4,572 mm and especially preferred of around 4,064 mm. The spacing between the mold inserts or cushions, in the preferred embodiments of the invention, are of similar dimensions. Alternatively, in certain embodiments of the invention, the elastomeric cushions will be formed on the carrier in a "bilayer" manner, wherein the base of the cushion will be formed of a relatively less elastic material, and the remainder will be of a higher elasticity. This feature will have the effect of increasing the amount of the consolidated fiber mat under the compressed cushion and thus the thickness and strength at the flange. In this aspectIt is important to note that when a panel of real tensioned skin fibers is produced, it is convenient to establish a balance between the compression and tension forces by the skins. Since the skin on one side of the present panel will cover 100% of the surface area of the grid cells, and the flange or skin on the other side will cover less than 100%, it may be convenient to provide a flange that is thicker than the first skin, so that the relative forces of the two faces of the panel are more closely balanced. Alternatively, the flange or second skin may be impregnated, for example with any number of known materials, such as resins, so as to alter the moduli of the elasticity, thereby effecting equilibria of relative forces, as described above. That is to say, at least the flanges, the use of a resin with a high modulus can compensate for the strength of the surface when the flange covers less than the surface area of the cell than approximately 50%. This additive may be preferable for laminating another sheet or skin on the face of the panel. Since the panel is not a solid member, the "apparent" modules of panel elasticity are measured using conventional methods for comparison with fiberboards and the like. It will be recognized that after a certain period of time, the elastomeric cushions "which are employed in the present invention may develop an" adjustment "deformation, which causes them to change their profile. Typically, elastomeric cushions become shorter and wider after repeated use. Thus, the configuration of the cushions of the present invention provide the advantage of anticipating this deformation, by providing a compensation configuration, as shown in Figures 1, 10, 11A-11C and 12A-12D. One embodiment of the method of the invention will now be described with reference to the drawings, in which Figure 2 illustrates the deposition of the flow of previously prepared fibers in a liquid carrier medium on the porous carrier 10 and between and on top of the elastomeric cushions 12. The transport fluid can be water, air, foam or other means, although water is preferred. The deposition of the fiber flow is a well-known technology and is an advantage of the invention using this developed technology. The fibers used in the present panels can be derived from cellulose material, such as wood fibers, recycled paper and wood products, and the like, fibers of agricultural, animal or textile origin. Additionally, the fibers may be derived from non-cellulosic materials, including synthetic fibers, such as various plastics and glass fibers, as well as mineral fibers, such as gum wool, and the like. Also the use in the present panels will be mixtures of fibers of various kinds, of cellulose origin or not. See, for example, the specifications of the patents of E. U. A., No. 4,702,870, 4,753,713, 5,196,236, 5,277,854 and 5,314,654. Examples of agricultural fibers include hemp, which is used for the manufacture of paper, rice straw or wheat, alone or in "fiber alloys", and also sources of potential fibers of the panel. Agricultural waste materials, such as palm leaves, are another possible source of fibers. Fibers of animal origin include wool, and textile fibers include cotton, where this wool and cotton can be recycled fibers. Other materials that can be dispersed in the fluid, preferably a liquid, can be used, such as cement, mortar, and gypsum.

Preferred fibers include recycled paper products, such as old corrugated containers (OCC), high quality recycled kraft paper, and normal mail that can not be delivered (USM). OCC fibers have a rapid formation time in the panel molding process and provide good fiber blends. Kraft paper is usually more expensive, but it empties quickly. In general, lower molding fibers have higher contamination regimes that can increase the casting time as well as adversely affect panel strength. Conforma the fibers are deposited and for a time later, the initial dosage of the fiber mat, as well as the removal of much of the water or other carrier fluid will occur naturally by gravity and / or by differential pressure, the flow out of the fluid it is illustrated by the large arrows in Figure 2. The differential pressure can be created by a vacuum below the porous carrier 10 or the environmental pressure increased above the deposited fibers. This initial densification can be accompanied by a "pre-pressing" step. However, a single pressure phase is preferably presented. Typical pressure times are 10 to 30 minutes. Typical emptying times are from 30 to 120 seconds.

Figure 3 shows the condition of the fibers deposited after gravity and / or differential pressure stage, in which the fibers are more or less uniformly distributed between and above the cushions. In this stage, there are fibers distributed loosely, as shown in Figure 3, which have very little structural integrity. Figure 3 further shows the initiation of a pressing step using a movable upper mold 14, as shown by the small arrows in this figure, a significant feature of certain embodiments of the present invention. During this step, the elastomeric cushions 12 will deform slightly in response to the normal pressure applied by the upper mold 14 as it moves toward the carrier 10. For the final pressure, a range of pressures of about 1.4 to 28 kg / cm2 are possible, and a range between 7 and 14 kg / cm2 is preferred, with 10.92 kg / cm2 being more preferred in one embodiment of the method of the present invention. Temperatures of 100 to 204 ° C for the water-based carrier fluid are preferred to achieve at least the boiling temperature of the water, more preferably 149 to 204 ° C and a temperature of 157 ° C is most preferred for a mode of the present method.

Furthermore, it will be appreciated that the response of the deformation of the cushions is not only parallel to the normal force exerted by the movable upper mold 14. This is due to the particular nature of the resilient materials used in making the cushions 12. It will also be seen in Figure 4 that the base portion of the elastomeric cushions 12 does not expand horizontally as the middle portion, resulting in exerting a consolidating force applied to the carrier 10 in the regions 16 surrounding the base of each cushion 12, producing a consolidation and compression of the fibers that surround the base of the cushion. In addition, the pressing step illustrated in Figures 3 and 4, remove the additional carrier fluid, the outward flow of the fluid is illustrated by the large arrows in Figure 3. The upper mold 14 can also be a porous carrier and the fluid Thus, it is clear from Figure 4, that the normal force applied to the upper mold 14 produces the three-dimensional densification of the deposited fibers due to the fact that the carrier is able to exit both through the porous carrier 10 as before and also through the upper mold 14. the resilience of the elastomeric cushions 12. The force applied in this pressure stage, illustrated in Figure 4, is sufficient to give the panel 18, illustrated in Figure 5, sufficient structural strength that can be removed from the carrier 10 and, if desired, transfer to a new location for further processing. The elastomeric cushions 12 in the present invention advantageously provide the lifting force for separating the panel from the carrier 10, as illustrated by the arrows in Figure 5. It may be convenient to use an air pressure through the carrier 10, to facilitate The panel removal Additional processes may include other pressure, panel trimming or other finishing activities to prepare the panel according to customary specifications. As illustrated in Figures 6 and 7, the panels produced with the invention are characterized by having a surface skin 20 on a side formed in cooperation with the upper mold 14, and bands and other configurations forming the open cell grid 22 are extend normal parallel to the surface skin 20. The remaining side of the panel 18 has a flange or second skin 24 molded integrally with the ribs forming the open cell grid 22, formed by the consolidation of the fibers in the regions 16 surrounding the bases of the elastomeric cushions 12. This flange or second skin 24 will cover a portion 26 of the surface area of the each cell 22 in the grid 22 of the panel 18, this portion can vary by adjusting the dimensions and elasticity of the cushion 12, as described above . The portion 26 of the surface area thus covered will be limited by the edge 28 of the flange and the wall 30 of the rib, which forms a portion of the grid 22. The remaining portion 32 of the cell surface area, through which the Elastomeric cushion 12 projects from the carrier 10, will thus remain uncovered. Continuing with the explanation of the present example using a two-stage process, as illustrated in Figures 1-4, the intermediate formed panel 18, which has been subjected to a primary pre-pressure to remove excess fluid, can now undergoing consolidation in the same apparatus or, optionally, transferring to a second apparatus (not illustrated in the figures) comprising a second porous carrier in which a second set of elastomeric cushions, which cooperate with a second upper mold, is mounted. The elements 10, 12 and 14 in Figures 1-4 are similar and functionally equivalent to the elements in this second stage, the dimensions and configurations being determined in order to produce a final finished panel, as described in more detail below. The use of a normal pressure force produces advantages in the invention. These advantages include energy savings in which a normal force is relatively easy to apply, and in addition, that the use of energy is less than that required in other systems, in which the forces must be applied in multiple directions to the mat, for produce the finished part. Figure 4 also illustrates the final stage in this embodiment of the invention. By simply holding the upper mold 14 in place for a predetermined period of time, which is adjusted by the nature of the panel 18 and the fibers and the like, used in its construction, the curing or final drying of the fiber structures can be achieved. in this last stage and heat can also be applied at this point. This can be done in ways well known to those skilled in the art by supplying a heating element in conjunction with either or both of the porous carriers and the upper molds. In a preferred embodiment, shown in Figures 11A-11C and 12A-12D, the cushions are approximately 14,224 mm in diameter at their base and have a height of about 14,732 mm above the carrier. The lower portion of the cushion extends for about 2,921 mm above the carrier, and the upper portion of the cushion extends for an additional 11,811 mm. The resulting dimensions of cell and flange thus form these cushions are the height of the rib, or maximum distance from the surface of the cell to the surface farthest from the flange, approximately 7,747 mm, with a cell thickness of approximately 1,651 mm, so that the total distance from the first skin to the second skin or side of the panel is about 9,525 mm. Thus, the subpanels joined together at their flanges, as shown in Figure 9, have a total thickness of about 19.05 mm. The width of the flange, measured between the cells, is around 4,064 mm. Figure 6A shows the relationship between the hanging r-r and the distance between cushions s. Preferably a ratio of r / s of 0.1 or 10% is formed, and more preferably a ratio of 0.3 to 0.4 or 30 to 40%. Thus, it is seen that a process of the described character has been supplied. The example of the two-stage process, which uses a first molding, as illustrated in Figures 1 to 4 and a second molding, is not considered to be limiting, since the result could be achieved in a single stage, as illustrated in FIGS. Figures 1-4 in multiple additional stages in the case that the panel is particularly complex in nature or requires further densification. In the case of a one-stage process using the present apparatus, the completion of the densification can be achieved simply by retaining the upper mold 14 in place for a predetermined length of time established by the nature of the panel 18 and the fibers and materials similar here used. In such a one-stage process, the final cure or drying of the fiber structure is achieved as a last step of Figure 4, and heat can also be applied at this point. The present technology can automate the process of the invention, so that the structural parts can be produced continuously or as individual elements. Other variations and equivalents will present themselves to experts in the field. Various embodiments of the invention may also use a flexible inflating membrane 12A, shown in Figure 8, which is preferably made of an elastomeric material, similar to the cushions 12 of Figures 1.6. A network 15 for supplying air or other fluid under pressure is supplied, and the openings 17 through the carrier 19 are provided to inflate the membranes. An upper mold 14A analogous to the upper mold 14 of Figures 3.4 is also provided. In operation, instead of the three-dimensional force that is generated internally within the material of the cushions 12, as a response to the normal pressure force, the fluid pressure under the active parts of the membrane serves this function. In addition, by appropriate design, the membranes can be constructed to supply analogous compressive regions 16A around the base, in order to form the consolidated flange or second panel skin 18, as previously described. The use of solid elastomeric cushions, as in Figures 1-5, is considered preferred where the overall thickness of the article being manufactured is relatively low. The membrane that can be inflated can be preferred where the overall thickness of the piece to be manufactured is relatively high. However, these considerations are not definitive and there is a substantial overlap as the parties do. Other factors also relate to the selection of which embodiment of the invention to use, such as the type of fibers, the density of the final product and similar factors, known to those skilled in the art. Molded taut skin fiber panels, formed in accordance with the present invention, can be used to manufacture structural panel panels, which insulate these panels by filling the internal spaces with glass fibers or other insulating material, and for floors, doors, roof slabs and for other such members. The panels can replace existing dry walls equally. A polyurethane or other coating can be used to waterproof the panels, for outdoor use. Any suitable adhesive can be used for the skin fibers 20A or 20B of the subpanel, to join the subpanels together in the rim skins, according to Figure 9. For example, an adhesive, such as polyvinyl acetate, or Alvar, can be used when using wood fibers. The invention can also be used in combination with mixed resins with the fibers. In such a case, the heat can serve with the additional function of hardening the final product by curing the resins. Additives for wet strength, such as MYMENE or HERCON, can be used, for example. It may be necessary to maintain the pressure in the panel, as in Figure 4, for a period of time sufficient to allow the resin to cure. However, depending on the particular resin, the heat may not be required at all. Thus, it can be seen that both basic variables of the invention include as solid or substantially solid cushions, blocks of resilient material, as well as inflatable membranes, in the alternative embodiments described herein. Although the above invention has been described in some detail in the form of illustration and example for purposes of clarity and understanding, it will be apparent to those skilled in the art, in light of the teachings of this invention, that certain changes and modifications may be made, without departing from the spirit or scope of the appended claims.

Claims (64)

1. An apparatus for manufacturing panels molded from a panel material dispersed in a fluid and employing the application of pressure on the dispersion in a mold, to reduce the content of the fluid and form said panel, this apparatus comprises a porous screen, a Through which fluid can flow during use, and a plurality of elastomeric cushions, mounted therein to mold the panel, the ratio of the spacing between the cushions and their height is from 0.15 to 0.50.

2. The apparatus of claim 1, wherein the ratio is from 0.20 to 0.40.

3. A method for manufacturing panels molded from a dispersed panel material within a fluid, which employs the application of pressure on the dispersion, in a mold, to reduce its fluid content, this method comprises: supplying a porous screen, for allow the expulsion of the fluid through it; supplying a plurality of elastomeric cushions, spaced on the screen, for molding said panel, the ratio of the spacing between the cushions and their height is from 0.15 to 0.50; deposit the scattered panel material in the fluid on the screen and around the cushions; and consolidating the deposited material and fluid around the cushions, compressing these cushions to deform them, in a direction substantially parallel to the screen, these cushions deform so that they protrude from the screen; whereby the material is consolidated between the cushions and under the protruding cushions, to form a panel surface having substantially normal ribs to the surface and ridges substantially parallel to the surface and through the ribs, to form a grid cell open on the panel.

4. The method of claim 3, wherein said ratio is from 0.20 to 0.40.

5. An apparatus for manufacturing molded panels, this apparatus comprises a porous screen and a plurality of mounted elastomeric cushions, these cushions can be compressed so that, during use, the panel material, deposited and consolidated around the cushions, forms a surface of panel, having integrally molded an open cell grid, this grid comprises ribs substantially normal to the surface and having a flange substantially parallel to said surface, each of the cushions having a base portion and a body portion above the base , this base has a width greater or equal to the width of the body, the cushions have a ratio of the height to the width of the base of approximately 0.85 to 2.0.

6. A method for manufacturing molded panels, comprising a sheet and a plurality of ribs and flanges extending therefrom to form an open cell grid, this method comprises: supplying a porous screen, to allow the expulsion of the fluid through the same; supplying a plurality of elastomeric cushions, spaced on the screen, to serve as molds to form the open cells of the grid, each of the cushions has a base portion and a body portion above the base, this base has a width greater or equal to the width of the body, these cushions have a ratio of height to width of the base of approximately 0.85 to 2.0; deposit the dispersed material in fluid on the screen and around the cushions; and consolidating and depositing the material and fluid around the cushions, compressing these cushions to deform them in a direction substantially to the screen, these cushions are deformed so that they protrude from the screen; whereby the material is consolidated between the plugs and under the protruding cushions, to form a surface of the panel ribs, substantially normal to said surface and having ridges substantially parallel to the surface and through the ribs, to form a grid cell open on the panel.

7. An apparatus for manufacturing molded panels, this apparatus comprises a porous screen and a plurality of mounted elastomeric cushions, these cushions can be compressed so that, during use, the panel material, deposited and consolidated around the cushions, forms a surface of panel having integrally molded a grid of open cells, this grid comprises ribs substantially normal to the surface and has a flange substantially parallel to the surface, each of the cushions comprising a base, an upper part and sides extending between them , the upper part and the base are substantially parallel to each other and the sides are substantially concave and generally extend mutually.

8. A method for manufacturing molded panels, comprising a sheet and a plurality of ribs and flanges extending therefrom, to form an open cell grid, this method comprises: supplying a porous screen, to allow the expulsion of the fluid through Of the same; supplying a plurality of elastomeric cushions, spaced on the screen, which serve as molds to form the open cells of the grid, each of the cushions having sides that are substantially concave and generally extend mutually; deposit the dispersed material in fluid on the screen and around the cushions, and consolidate and deposit the material and fluid around the cushions, compressing these cushions to deform them in a direction substantially to the screen, to form protruding parts between the cushions. the cushions and the screen; whereby the material is consolidated between the pads and under the protruding parts, to form a surface of the panel ribs, substantially normal to said surface and having ridges substantially parallel to the surface and through the surface. the ribs, to form a grid cell open on the panel.

9. An apparatus for manufacturing molded panels, comprising a porous screen and a plurality of mounted elastomeric cushions, these cushions can be compressed so that, during use, the panel material, deposited and consolidated around the cushions, form a surface of panel having integrally molded a grid of open cells, this grid comprises ribs substantially normal to the surface and having a flange substantially parallel to the surface, the ratio of the protruding part of each cushion, when compressed, to the distance between the cushions is at least 0.1.

10. A method for manufacturing molded panels, comprising a sheet and a plurality of ribs and flanges extending therefrom to form an open cell grid, this method comprises: supplying a porous screen, to allow the expulsion of the fluid through the same; supplying a plurality of elastomeric cushions, spaced on the screen, which serve as molds to form the open cells of the grid; deposit the dispersed material in the fluid on the screen and around the cushions; and consolidating the deposited material and fluid around the cushions, compressing these cushions to deform them in a direction substantially to the screen, these cushions deform so that they protrude from the screen; whereby the material is consolidated between the cushions and under the protruding parts, to form a surface of the panel ribs, substantially normal to said surface and having ridges substantially parallel to the surface and through the ribs, so as to forming a grid cell open on the panel, the ratio of the protruding part of the cushion to the distance between them is at least 0.1.

11. A plurality of elastomeric cushions, for use in an apparatus for manufacturing molded panels, these cushions can be compressed so that, during use in the apparatus, the panel material deposited around the cushions forms a panel surface having integrally molded a grid of open cells, this grid comprises ribs substantially normal to the surface and having a flange substantially parallel to the surface. surface, each of the cushions has a base portion and a body portion above the base, this base has a width greater than or equal to the width of the body, the cushions have a ratio of height to base width of about 0.85 up to 2.0.

12. The cushions of claim 11, wherein the ratio of the height to the base is from about 0.9 to 1.8.

13. The cushions of claim 12, wherein the ratio of the height to the base is from about 1.0 to 1.5.

14. The cushions of any of claims 11 to 13, wherein each of these cushions has an upper width such that the cushions have a ratio of the width of the base to the upper width of approximately 1.4.

15. The cushions of any of the claims 11 to 15, wherein the cushions have a Shore A hardness of 15 to 45.

16. The cushions of any of claims 11 to 14, wherein the cushions have a cross section of a substantially hexagonal configuration.

17. An apparatus for manufacturing molded panes, comprising a porous screen and a plurality of elastomeric pads, as claimed in any of claims 12 to 18.

18. A plurality of elastomeric cushions, for use in an apparatus for manufacturing molded panels, these cushions may be compressed so that, during use in the apparatus, the panel material deposited around the cushions forms a molded panel surface. integrally a grid of open cells, this grid comprises ribs substantially normal to the surface and having a flange substantially parallel to the surface, each of the cushions has a base, an upper part and sides, extending between them, the part The upper and the base are substantially parallel to each other and the sides are substantially concave and extend generally parallel to each other.

19. The cushions of claim 18, wherein the sides are biangular.

20. The cushions of claim 19, wherein each of the sides comprises a lower portion, having an angle of about 15 degrees, measured from the normal to the bottom, and an upper portion, having an angle of about 8 degrees, measured from the normal to the background.

21. The cushions of any of claims 18 to 20, wherein each of these cushions has an upper width such that the cushions have a ratio of the base width to the upper width of approximately 1.4.

22. The cushions of any of claims 18 to 21, wherein the cushions have a Shore A hardness of 15 to 45.

23. The cushions of any of claims 18 to 22, wherein the cushions have a cross section of a substantially hexagonal configuration.

24. An apparatus for manufacturing molded panels, comprising a porous screen and a plurality of elastomeric cushions attached thereto, as claimed in any of claims 19 to 23.

25. An apparatus for manufacturing molded panels of tensioned skin fibers, comprising an open cell grid, this apparatus comprises: a porous carrier; a plurality of elastomeric cushions, located on the carrier; elements for depositing fibers on the carrier, to cover and fill the spaces between these cushions, each of the cushions has a predetermined size and configuration, in order to exert pressure on the deposited fibers that surround the cushion, when this cushion is compressed, these elements for depositing the fibers comprise a technique of the carrier fluid, in which this carrier fluid exits through the deposited fibers and through the carrier; and a device for consolidating the deposited fibers, during use, in directions both normal and parallel to the carrier, by applying normal pressure to the carrier on the cushions, at their remote ends from the carrier; whereby the cushions are made to expand parallel to the carrier, to compress the fibers located between them, as well as to consolidate the fibers placed above and below the compressed cushions.

26. A method for manufacturing a panel of tensioned skin fibers, including a grid of open cells from the fibers, comprising the steps of: supplying a porous carrier; supplying a plurality of elastomeric cushions, located on the carrier; placing the cushions on the carrier, in predetermined spaced relationships with each other; depositing fibers on the carrier, to cover and fill the spaces between these cushions, each of the cushions has a predetermined size and configuration, in order to exert pressure on the deposited fibers that surround the cushion, when this cushion is compressed, these elements for depositing the fibers comprises a technique of the carrier fluid, in which this carrier fluid exits through the deposited fibers and through the carrier; and consolidating the deposited fibers, during use, in both normal and parallel directions to the carrier; whereby the cushions are made to expand parallel to the carrier, to compress the fibers located between them, as well as to consolidate the fibers placed above and below the compressed cushions.

27. The apparatus of any of claims 1, 5, 7, 9 or 25, wherein the ratio of height to width of the base of the cushions is from about 0.9 to 1.8.

28. The apparatus of claim 27, wherein the ratio of height to width of the base of the cushions is from about 1.0 to 1.5.

29. The method of any of claims 3, 6, 8, 10 or 28, wherein the ratio of the height to the base width of the cushions is from about 0.9 to 1.8.

30. The method of claim 29, wherein the cushions have a ratio of the height to the base width of the cushions is from about 1.0 to 1.5.

31. The apparatus of any of claims 1, 5, 9, 25 or 27, wherein the cushions have sides extending away from the screen, and the sides are substantially concave and generally extend mutually.

32. The apparatus of any of claims 7 or 31, wherein the sides are bi- angular.

33. The apparatus of claim 32, wherein the sides of the cushion form a lower portion having sides of an angle of approximately 15 degrees, measured from the normal to the screen and an upper portion having an angle of approximately 8 degrees, measured from the normal to the screen.

34. The method of any of claims 3, 6, 10, 26 or 29, wherein the cushions have sides extending away from the screen, these sides are substantially concave and extend generally with each other.

35. The method of claim 8 or 34, wherein the cushions are biangular.

36. The method of claim 35, wherein the sides of the cushion form a lower portion, having sides of an angle of approximately 15 degrees, measured from the normal to the screen and an upper portion having an angle of approximately 8 degrees. , measured from the normal to the screen.

37. The apparatus of any of Claims 1, 5, 7, 9, 25, 27 or 31, wherein the cushions have a Shore A hardness of about 15 to 45.

38. The apparatus of claim 37, wherein the cushions have a Shore A hardness of about 27.

39. The method of any of claims 3, 6, 8, 10, 26, 29 or 34, wherein the cushions have a Shore A hardness of 15 to 45.

40. The method of claim 39, wherein the cushions have a Shore A hardness of about 27.

41. The apparatus of any one of claims 1, 5, 7, 9, 25, 27, 31 or 37, wherein the cushions are spaced by approximately 1.524 to 5.08 mm.

42. The apparatus of claim 41, wherein the cushions are spaced by approximately 3,302 to 4,572 mm.

43. The apparatus of claim 42, wherein the cushions are spaced by 4064 mm.

44. The method of any of claims 3, 6, 8, 10, 26, 29, 34 or 39, wherein the cushions are spaced by approximately 1.524 to 5.08 mm.

45. The method of claim 44, wherein the cushions are spaced by approximately 3.302 up to 4. 572 mm

46. The method of claim 45, wherein the cushions are spaced by approximately 4,064 mm.

47. The apparatus of any one of claims 1, 5, 7, 9, 25, 27, 31, 37 or 41, wherein the cushions have a cross section of substantially hexagonal configuration.

48. The method of any of claims 3, 6, 8, 10, 28, 29, 34, 39 or 44, wherein the cushions have a cross section of substantially hexagonal configuration.

49. The apparatus of any of claims 1, 5, 7, 9, 25, 27, 31, 37, 41 or 47, wherein each of the cushions has an upper width such that these cushions have a ratio of the width of the base to the width of the top of 1.0 to 1.7.

50. The apparatus of claim 49, wherein each of the cushions has such a width of the top that these cushions have a ratio of the width of the base to the width of the top of about 1.4.

51. The method of any of claims 3, 6, 8, 10, 26, 29, 34, 39, 44 or 48, wherein each of the provided cushions has a width of the top so that these cushions have a relationship from the width of the base to the width of the top of 1.0 to 1.7.

52. The method of claim 51, wherein each of the cushions has a width of the upper pare that these cushions have a ratio of the width of the base to the width of the upper part of approximately 1.4.

53. The apparatus of any of claims 1, 5, 7, 9, 25, 27, 31, 37, 41, 47 or 49, wherein the cushions are made of silicone rubber.

54. The method of any of the claims 3, 6, 8, 10, 26, 29, 34, 39, 44, 48 or 51, in which the cushions are made of silicone rubber.

55. The apparatus of claim 5, 7, 17 or 24, further comprising a press for consolidating, during use, the panel material and the fluid around the pads and to cause the pads to deform in one direction. substantially parallel to the screen, this deformation of the cushions comprises a protruding part of these cushions on the screen, the panel material consolidated between the cushions and under the projecting part that forms the ribs and flanges.

56. A fiber-molded, tensioned skin panel, comprising: a fiber member, of skin tensioned, substantially continuous; a grid of fibers, comprising a plurality of open cells defined by a plurality of ribs, having their thicknesses parallel to the plane of the grid and their heights defining the thickness of this grid, the grid is molded integrally with the grid member. Tightened skin fibers; and a fiber flange member, integrally molded with the grid, wherein this flange member extends over at least a portion of the surface area of each grid cell on a side opposite the tensioned skin fiber member.

57. A molded fiber panel, formed by the method of any of claims 3, 6, 8, 10, 26, 29, 34, 39, 44, 48, 51 or 54, and comprising a sheet having a plurality of ribs and ridges, extending therefrom, to form a grid of open cells.

58. A panel molded of fibers, formed by joining together two panels, according to claims 56 or 57.

59. The panel of any of claims 56 to 58, wherein the ridges extend over 5 to 80% of the surface area of each cell of the grid.

60. The panel of claim 59, wherein the ridges extend from 25 to 40% of the surface area of each cell of the grid.

61. The panel of any of claims 56 to 60, wherein the ratio of the protruding part of the flanges to the width of these flanges is at least 0.1.

62. The panel of any of claims 56 to 61, wherein the grid comprises cells of a substantially hexagonal configuration.

63. The panel of any of the claims 56 to 62, in which the panel material is selected from wood fibers, agricultural fibers, mineral fibers, synthetic fibers, and mixtures thereof.

64. The panel of any of claims 56 to 62, wherein the material of the panel is selected from cement, mortar and gypsum.