US20160097154A1

US20160097154A1 - Engineered leather for airbag, steering wheel, and seatbelt applications

Info

Publication number: US20160097154A1
Application number: US14/503,953
Authority: US
Inventors: Conrad C. Dumbrique; Adam T. Vile; Chandrakanth Siddharthan; Uriel P. Hernandez
Original assignee: Autoliv ASP Inc
Current assignee: Autoliv ASP Inc
Priority date: 2014-10-01
Filing date: 2014-10-01
Publication date: 2016-04-07
Also published as: WO2016053487A1

Abstract

Methods of covering portions of an automobile interior with an engineered leather are provided. When a mold of the appropriate shape is provided, a cell paste can be placed therein and grown into a leather, which can be tanned and treated to produce a suitable covering for a portion of an automobile interior, such as a steering wheel, an airbag cover, or a seat belt assembly. A method of growing a seamless automobile component cover in situ is disclosed.

Description

FIELD OF THE INVENTION

The present invention relates to finishes and methods of coating objects. More particularly, it relates to the use of cultured or engineered leather to cover surfaces of automobile components. Even more particularly, the present invention relates to coverings for automotive components such as steering wheel armatures, air bags, safety belt parts, door panels, and other surfaces made from one or more layers of laboratory-grown, cultured, or engineered leather, which have been grown inside of a mold constructed in the proper dimensions for production of said coverings.

BACKGROUND

Leather has been used in a great variety of luxury and durable goods. One notable use of leather has been in the trim of automobiles, particularly as seat and steering wheel coverings. However, there are disadvantages to using leather. For instance, the hide of an animal must be acquired, treated, cut, and sewn to the appropriate size and shape. Animals such as cattle which are raised for this purpose require great amounts of feed and space, and raising them can be relatively expensive. The treatment of leather can be a lengthy process and can also involve the use of toxic compounds, such as chrome salts. Because the leather must be shaped and cut to fit the component it is to cover, scraps are produced and discarded. Finally, the thickness and toughness of the leather can make it difficult to create predictable seams with a good fit during the fixation step to the surface.
Materials have been developed to function as artificial leathers, but these generally consist of a base layer of fabric covered with a plastic. As such, these artificial leathers lack the tactile characteristics and the durability of genuine leather and can be perceived as unsuitable even for decorative use by consumers.
Therefore, a way of preshaping a piece of leather such that minimal or no sewing is required to attach the leather to an article to be covered would be advantageous. Moreover, a leather that would not need to be cut or derived from the intact skin of a donor animal would aid in cost savings and efficiency.

BRIEF SUMMARY

In a first embodiment, the invention provides a covering for an article having an outer surface, the covering having at least one layer of at least one type of engineered leather, the engineered leather having been cultured in a mold. The mold has a bottom portion and a top portion, a cell growth space being defined between the bottom portion and the top portion. In particular, the article may be a component of an automobile interior.
In another embodiment, the invention provides a method of covering an article with at least one layer of at least one type of engineered leather. In a first step, a mold with a top portion and a bottom portion is provided. In a second step, a cell aggregate is provided and placed on the bottom portion of the mold. In a third step, a quantity of tissue culture medium is provided to the cell aggregate. In a fourth step, the top portion of the mold is placed over the cell aggregate. In a fifth step, the article is placed in a chamber adapted to allow for cell growth. In a sixth step, the cells are allowed to grow until they form an engineered leather within the mold. Finally, in a seventh step, the mold is removed to form a covering for the article.
In another embodiment, a method of forming a preshaped engineered leather for covering an article with at least one layer of at least one type of engineered leather is provided. In a first step, an article having an outer surface is provided. In a second step, a mold having an inner surface for growing cells is provided. In a third step, a cell aggregate is provided and placed on the inner surface of the mold. In a fourth step, a quantity of tissue culture medium is provided to the cell aggregate. In a fifth step, the article is placed in a chamber adapted to allow for cell growth. In a sixth step, the cells are allowed to grow until they form an engineered leather within the mold. Finally, the mold is removed to form a covering for the article.
In a further embodiment, the invention is characterized by an engineered leather having a substantially cylindrical shape formed by the steps of placing a cell paste on a cell-growth surface of a substantially cylindrical mold, placing the mold in an incubator, permitting cell growth until a substantially cylindrical leather is formed, removing the substantially cylindrical leather from the mold, and treating the leather.
Further objects, features, and advantages of the present invention will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating steps of one method of covering an article in a layer of engineered leather in accordance with one embodiment of the present invention;

FIG. 2 is an illustration of steps involved in covering a steering wheel in a layer of engineered leather in accordance with one embodiment of the present invention;

FIG. 3 is an illustration of a process wherein leather is cultured within a mold to cover a steering wheel in accordance with embodiments of the present invention;

FIG. 4A is a perspective view of a steering wheel which has a heating element and an engineered leather cover in accordance with another embodiment of the present invention;

FIG. 4B is a perspective view of a steering wheel armature having a selective leather finish in accordance with another embodiment of the present invention;

FIG. 5A is a cross-sectional schematic view of the arrangement of layers of a prior art steering wheel armature;

FIG. 5B-5C are cross-sectional schematic views of the arrangement of layers of steering wheel armatures in accordance with embodiments of the present invention;

FIG. 6 is a schematic cross-sectional view of a steering wheel armature which is adapted to be coated by leather culturing in situ;

FIG. 7A-7C are illustrations of other automotive components which are amenable to the growth of engineered leather in situ in accordance with further embodiments of the present invention; and

FIG. 8A-8C are perspective views of a variety of molds for culturing a preshaped engineered leather in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS

The description that follows is not intended to limit the scope of the invention in any manner, but rather serves to enable those skilled in the art to make and use the invention.
It is to be understood that the figures are schematic and do not show the various components to their actual scale. In many instances, the figures show scaled up components to assist the reader.
The terms “substantially” or “about” used herein with reference to a quantity includes variations in the recited quantity that are equivalent to the quantity recited, such as an amount that is equivalent to the quantity recited for an intended purpose or function.
The terms “engineered leather,” “cultured leather,” “lab-grown leather,” and “laboratory-created leather” are used interchangeably herein to refer to a leather product which, at least in part, is grown in vitro or not directly harvested from a host animal.
Although cultured, engineered, or lab-grown leathers have been proposed, to date these have involved creation of sheets of leather which still need to be finished, cut, and sewn in order to be incorporated into a final product. In contrast, the present invention provides an engineered leather that has been grown in a mold into substantially its final shape in order to minimize waste and processing time and costs.
Leather receives its characteristic look and toughness from the layers of animal skin from which it is made. The outermost layer of skin of a mammal is the epidermis, which lies above a basement membrane that separates it from the dermis or corium. The epidermis is made up generally of keratinocytes.
The basement membrane is a network of proteins that forms a portion of the extracellular matrix (ECM.) In the case of skin, the ECM is made up largely of collagens, though other fibrous proteins and glycosaminoglycans and other types of protein are also present. Collagen is secreted by collagen-secreting cells. Present within the matrix can also be fibroblasts, which among other things secrete elastins, proteins which give elasticity to the skin tissue, in contrast to the strength and structure imparted by collagen. The dermis is linked to the epidermis by this extracellular matrix.
Collagens are important proteins not only because of their abundance and their structural properties which keep the skin intact in a living animal, but because the leather tanning process chemically alters the structure of the collagen component of a skin that is treated. In general, more collagen makes for a stronger leather. For that reason, the use of collagen as an additive to increase the strength of a cultured leather is considered in view of the present invention.
The engineered leather should be hairless and as free from blood vessels and other such disruptive physiological structures as possible. This can be achieved either by selecting for progenitor leather samples to expand or by making advantageous genetic mutations in a leather sample using known molecular biology or nucleic acid manipulation techniques. Such modifications could be made to target genes to, for example, accelerate proliferation, prevent follicle formation, minimize vascularization, and so forth.
Turning now to the cells to be used, these can be from a variety of sources and presented in a variety of formats. In one instance, the primary source of the skin cells can be a skin punch from a mammal, such as cattle. Because of the potency of in vitro tissue culture techniques, a small punch (about 1 cm in diameter) can be sufficient to grow an indefinitely large number of cells if handled properly. The cells from such a skin punch can be expanded and eventually form the basis for a cell aggregate such as a cell paste for leather formation.
After the precursor cells have been obtained and, if the initial quantity was insufficient, expanded, a cell paste or cell aggregate can be made. This can be achieved by mixing cells or cell aggregates (of one or more cell types) and a cell culture medium, preferably in a pre-determined ratio, to create a cell suspension. Alternatively, if cells have been obtained and grown in suspension, they can be concentrated to achieve the desired cell concentration (density), viscosity, and consistency required for the cell paste. In some embodiments, compounds or artificial matrices are combined with the cell suspension to enhance the physical characteristics of the cell paste. These additives can include for example collagen, hydrogels, MATRIGEL, and the like. A cell paste may have a generally amorphous or unorganized structure, or may comprise an aggregate having a specific shape, such as a sphere, an elongated strip, or any other shape.
In one embodiment, the cell paste can be placed onto a surface or into a mold as-is. In another embodiment, a structured multicellular body can be further fabricated from the cell paste. The cell paste can be shaped into a desired shape, including but not limited to a sphere, a sheet, a cylinder, or any other shape necessary for practicing a particular application of the invention. The cell paste can be placed in a controlled environment, such as an incubator with a relatively high humidity level and carbon dioxide provided, to allow the cells to adhere to one another or to be distributed throughout the provided cell growth matrix to form the desired shape.
Any type of incubator or bioreactor which is suitable for cell growth may be chosen for the culturing of cells for an engineered leather growth application in accordance with the principles of the present invention. For instance, a conventional bioreactor may be selected. Alternatively, a rotating bioreactor having an outer casing or external sleeve which produces a varying electromagnetic field to optimize cell growth may also be chosen. In the latter case, the mold should be made of a material which does not interfere with the electromagnetic field.
In one embodiment, the engineered leather can have an initial culturing step wherein precursor sheets of cells are arranged on a support which may optionally be biodegradable and which permits the precursor sheets to grow together and form a substantially cohesive and planar layer. In some embodiments, these layers are arranged horizontally and/or vertically adjacent to one another.
The matrix in which the cell paste is formed is biocompatible and ideally biodegradable. That is, as the cells grow and proliferate within the matrix or scaffold, the nutrients from the tissue culture medium as well as the matrix itself can be consumed by the cells and give way to a self-supporting skin structure. Cells should be largely free of pores, fibrous tangles, or other structure of the scaffold.
Tissue culture medium is supplied to the cultured cells. Although the precise composition of the medium can be altered according to the overall health of the cell population, a minimal essential medium (MEM) which contains salts (such as calcium chloride, sodium chloride, potassium chloride, sodium carbonate, magnesium sulfate, and sodium phosphate), amino acids, vitamins (such as calcium pantothenate, I-inositol, riboflavin, choline chloride, nicotinamide, thiamine hydrochloride, folic acid, and pyridoxal hydrochloride), and other components, particularly D-glucose, sodium pyruvate, and lipoic acid, provides a basis for the medium. Further to this, an enriching component such as a serum may be included to create a rich medium. Acceptable enriching components include but are not limited to horse serum, fetal bovine serum, and human platelet lysate. Advantageously, a protein-rich mixture which is low in antibodies and which can provide growth factors may be selected. The medium should be buffered to a pH that will keep the cell growth matrix intact and will allow for proliferation of cells.
The tissue culture medium can be further supplemented with substances that will aid in tissue growth and cultured leather formation. Growth factors, hormones, and other molecules that encourage cell proliferation in a general way can be included to maintain or increase proliferation. ECM components such as collagen can be provided exogenously in order increase the strength of the intercellular protein scaffold. If genetic modifications including the addition of selectable markers were made prior to culturing and expansion in the incubator or bioreactor, a drug for selection could be added. Molecules such as G418, zeocin, puromycin, hygromycin B, and blasticidin can be provided in this manner, dependent upon the genetic background of the particular cell line.
In addition, antibiotics such as streptomycin and penicillin can be added prophylactically in order to prevent growth of microbes in the tissue culture media or cell growth scaffold.
Turning now to FIG. 1, a flowchart listing steps for creating of an engineered leather inside of a mold is provided. In a first step 10, a mold is provided, designed with the dimensions of the object to be covered taken into account. In one embodiment, the mold has dimensions, including a height, a width, a length, an inner diameter, an outer diameter, or another dimension, that is substantially equal to the size of the outer surface to be covered. In another embodiment, the dimensions of the mold may be larger than the object to be covered in any one or any combination of dimensions. The mold may be about 5% larger, or about 10% larger, or about 15% larger, or about 20% larger, or about 25% larger, or between 0%-25% larger than the object to be covered in one dimension or in any dimension to account for shrinkage of the leather during treatment or formation of functional or decorative elements in the leather, such as a seam. The mold can allow for growth of a leather in substantially two dimensions, such as for a planar covering of an article, or in three dimensions (length, height, and width) which permits growth of a leather that has substantially the same shape or a similar shape to a more complex-shaped surface, such as a cylinder, a cone, a sphere, or a combination of geometric solids.
In a second step 20, the cell paste is placed on a surface of a mold. As mentioned before, the cell paste can be provided as a series of substantially spherical particles, or as sheets, or as layers, or as a substantially amorphous paste which is spread onto the cell growth surface of the mold. The mold controls the shape and extent of cell growth. In cases where a cell aggregate is placed upon the article itself for expansion, the mold will define the outer limit of cell growth and eventual leather formation.
The mold may be constructed of separate parts, such as a top portion and a bottom portion that fit together in order to provide a cell growth space there between. The top and bottom portions of the mold may form a weak seal that is slightly permeable to air and humidity within the incubator or bioreactor. Alternatively, the mold may be of a single-piece construction, such as with a hinge member, that closes upon itself to create a cell growth space on an inner surface of the mold. Whether made of separate parts or as a single piece, the portions of the mold that come together to provide a cell growth surface may have different cavity profiles from one or another, or the cavity profiles may be the same throughout the parts of the mold.
The surface of the mold upon which cells grow should be sterile and biocompatible, such that it will keep its shape when cell paste, cell matrix or scaffold, and tissue culture medium are added. In one embodiment, the surface of the mold is treated such that it does not promote adhesion of the cells directly to it. In another embodiment, the cells attach to the surface to some degree during the culturing process, but are readily removed from the surface (such as by adding trypsin) but the cells or layers of cells remain cohered to one another and to the other layers of the engineered layers.
To assist with initial adhesion of the cell paste, the cell growth surface of the mold may be coated with a biocompatible and easily removed or incorporated material such as agar or agarose. Additionally or alternatively, the surface may be roughened or have grooves formed thereupon in order to create surfaces amenable to cell invasion and growth. A roughened surface also has the benefit of producing a texture which has the same tactile qualities of natural leather.
In a third step 30, the cells are cultured. The culturing step may include placing the cells in an incubator or bioreactor for at least about one night, or about one day, or about two days, or about four days, or about one week, or about two weeks, or about a month, or about two months, or about one day to about 60 days, depending on the size of the article to be covered. During this time the cells will ideally be monitored and checked every 24 hours or about every 48 hours and appropriate media changes conducted. Different supplements or even different types of tissue culture media may be employed at various times in the culturing process.
As the cells are cultured, the engineered leather forms by fusion of cellular bodies which were initially separate from one another. A collagen matrix forming between layers of cells can help to give the nascent leather desirable strength and structural properties. The collagen may be secreted by cells, such as fibroblasts, and can also be provided at various times during the culturing step to be incorporated by the growing leather bodies or layers into an extracellular matrix. The ECM helps these leather bodies to retain their shapes and to adhere to one another.
In an optional fourth step 40, the mold is removed. In a case where the leather is likely to retain its three-dimensional shape without the mold, such as a covering for a substantially planar part such as a seat belt buckle D-ring, one or more portions of the mold may be removed. In one embodiment, the top portion of the mold may be removed to expose the outer, cosmetically appealing, epidermal layer of the cultured leather. In one embodiment, the top and bottom portions of the mold are removed, allowing all sides of the engineered leather to be exposed.
In an optional fifth step 50, the leather is treated after growth is complete. In one embodiment, treatment of the leather is equivalent to tanning of the leather. In another embodiment, the treatment process can include tanning and at least one of preserving, soaking, bating, pickling, depickling, thinning, retanning, lubricating, crusting, wetting, sammying, shaving, rechroming, neutralizing, dyeing, fatliquoring, filling, stripping, stuffing, whitening, fixating, setting, drying, conditioning, milling, staking, buffing, finishing, oiling, brushing, padding, impregnating, spraying, roller coating, curtain coating, polishing, plating, embossing, ironing, glazing, tumbling, and any other leather treatment known in the art.
In one embodiment, the leather can be treated free from the entire mold. In another embodiment, the leather may be treated while still associated with a portion of the mold.
In an optional tanning step, the leather may be tanned by any known method, including using vegetable tannins; using at least one chromium salt, in one embodiment a chromium sulfate; employing aldehyde tanning; and tanning by use of aromatic polymers, referred to as syntans.
When any desired combination of tanning and treatment steps are complete, the engineered leather can be incorporated into an article. In one case, a cover for a steering wheel which has been treated without the presence of a portion of a mold can be fitted over said steering wheel and stitched at a seam, which preferably faces away from the driver.
In an optional step 60, further coatings (such as wear-resistant, water resistant, and stain-resistant treatments) can be applied to the leather. This step can occur prior to attachment to the article or after it has been secured to the part to be covered.
FIG. 2 illustrates a typical process for layering in the manufacture of a leather-covered steering wheel. At first, an armature 101 of a steering wheel 100 is provided with hub 102 at its center and spokes connecting the hub 102 to the armature 101. The armature 101 can be of any suitable material, particularly aluminum or magnesium, and in any size and shape commensurate with the size of the vehicle and driver's seat where it will be employed.
In a first covering step 81, a layer of polyurethane (PU) foam 110 is distributed substantially uniformly over a portion of the surface of the armature 101. This layer provides a cushioned grip to the user and also softens the steering wheel in case of collision. In a second covering step 82, a heating element 120 is optionally incorporated into the steering wheel. In a third covering step 83, a layer of leather 130 is placed over the PU foam. In a fourth covering step 84, the heating element is covered with covering 140, which can be at least one of a wood veneer or a leather. If leather, covering 140 may be identical to leather 130, or may represent a second type or style of leather. If identical to leather 130, the covering 140 may be continuous and integral with leather 130, or may be a separate piece. Steps 82, 83, and 84 are all optional, and steering wheels without heating elements, without veneer trim, without a second type of leather, and with leather in a single piece covering the entire steering wheel armature are all considered to be within the scope and spirit of this invention.
Referring now to FIG. 3, a mold 350 for growing an engineered leather cover for a steering wheel 300 is shown. The mold has dimensions that are slightly larger than the steering wheel 300 itself. In the illustrated embodiment, the mold 350 is constructed of a single piece, although a mold having a top portion and a bottom portion for cell growth in a space there between is also a contemplated configuration. In the case of one-piece mold 350, the mold 350 has an outer surface and an inner surface. The inner surface is adapted for cell growth. The single-piece mold has a slit 303 running around at least a portion of the diameter of the mold and serves to allow access to the inner surface. The slit 303 allows for introduction of cells into the mold, cell culture medium and supplements during the growth phase, and importantly for extraction of the engineered leather after culturing is complete.
In a first step 391, cell paste 318 is deposited into the interior of the mold which has been optionally treated to allow cells to adhere, or, contrarily, to be biocompatible but prevent substantial adhesion. After the cells are introduced, the mold is placed in an incubator or bioreactor and maintained until the mold is filled with an engineered leather of the desired size and shape. In a second step 392, the engineered leather is extracted from the mold, in one embodiment through the slit 303, and transferred or bonded onto a steering wheel armature 300 which has an outermost polyurethane (PU) foam layer 310. In a third step 393, the slit 303 is closed to form a new outer layer of the steering wheel by stitches 313.
It is to be noted that the engineered leather coating can be achieved in a number of ways. In one embodiment, a more traditional and thicker leather may be grown within the mold and be treated as usual. In other cases, a thinner piece of leather may suffice, particularly if the construction of the PU foam layer of the steering wheel (or other foams or cushions molded into the steering wheel) can effectively simulate the feel of leather. In other cases, such as a covering for an airbag, a thinner leather that sufficiently gives a luxurious visual appearance, may be sufficient to constitute a covering consistent with the principles of this invention.
Growing a cultured leather in this manner has a great number of advantages over obtaining leather in a conventional way. First, there is little to no waste produced by cutting down a sheet of leather when a molded engineered leather is utilized. Second, treatment uses fewer toxic chemicals because of the minimized size of the molded leather. Third, minimal shaping and stitching of potentially tough leather is required. Fourth, no animal needs to be acquired, raised, fed, housed, and ultimately slaughtered in the production of the leather good. Fifth, this method is superior even to other cultured leather methods because the prior art engineered leather methods result in formation of a sheet of leather that must still be cut to size and stitched like a conventional piece of leather.
FIG. 4A illustrates a completed steering wheel 400 in accordance with another embodiment of the present invention. In this case, not only was cell paste introduced to the mold, but a heating element 420 was incorporated as well. The heating element 420 as illustrated in FIG. 4A is a web of thermally-conductive material which effectively extends around the entire circumference of the steering wheel on which it is placed, although many different configurations are envisioned to be within the scope of the present invention, including but not limited to a thermally-conductive heating element formed as a single coil, which extends around only a portion of the circumference of the heating element. Multiple heating elements 420 may also be incorporated. The heating element 420 may be placed within the mold which is adapted for cell growth and leather shaping therein. The heating element 420 may optionally be treated to encourage cell adhesion to its surface. The cell paste is spread not only through the interior of the mold for cell growth but also makes contact with the heating element 420. As the cells proliferate, they fill gaps in the heating element, and in some embodiments grow over them, surrounding them entirely in engineered leather. When growth and treatment is complete, the combined leather/heating element is placed over the steering wheel and stitched, with the heating element being connected to a power source for operation during times when warming is required.
In the embodiment illustrated in FIG. 4B, another variation on the molded engineered leather is shown. In this case, a first covering portion 430 made of cultured leather fashioned in a striated pattern is shown. In this case the mold has features such as for instance grooves in which the cell paste is deposited and allowed to proliferate. The engineered leather can then be extricated from the mold and placed over the steering wheel 400 to form a decorative pattern on its own, or a second type of leather 440 with different tactile and/or visual characteristics can be grown in the spaces between the striations to form a unique and otherwise technically difficult to execute steering wheel cover.
Referring now to FIG. 5A-5C, the advantages of employing a cultured leather which has been grown in a separate mold or on the article itself in covering a steering wheel over the existing prior art method are described.
FIG. 5A illustrates a cross section of a prior art steering wheel 500. In constructing such a steering wheel, a layer of PU foam 510 forms the initial cushioning layer on the armature. Notch 541 is cut out of the PU foam layer 510, or molded during creation of such a layer. Support 547 is laid over a portion of PU foam layer 510 and veneer 540 is placed over support 547. A portion of veneer 540 is placed into notch 541. Veneer 540 must be cut or formed to have a variety of thickness and a non-uniform shape across its length since it wends into the notch 541 and creates another notch which is represented at butting junction 542.
Heating element 570 is positioned over another portion of PU foam layer 510 and over a portion of veneer 540 proximate to butting junction 542. Then leather 530 is stretched over heating element 570 and into the notch formed by veneer 540 at butting junction 542. At this point the leather is pulled into the notch in the veneer and may be glued in. The leather is also stitched around the steering wheel at a defined seam, and any excess must be trimmed off.
In contrast, FIG. 5B illustrates a leather-and-veneer steering wheel covering in accordance with the principles of the present invention. In this case, the veneer 640 is laid in a substantially uniform layer over the PU foam layer 610. The engineered leather 630, which has been grown in a mold as described previously in this disclosure, is slipped over the steering wheel and creates a transition point 643 at the leather/veneer junction. The leather can then be stitched around the steering wheel as usual. Covering a steering wheel in this way is much simpler than in the prior art and does not require cutting or forming pieces into relatively complex geometries.
FIG. 5C shows a cross section of a steering wheel covering which is similar to the one illustrated in FIG. 5B, but with an artificial seam 648 placed at the transition point 643 between the leather and veneer layers. Such a seam may have a decorative purpose. The steering wheels of FIG. 5B and FIG. 5C can each incorporate a heating element as part of their designs.
In an alternative embodiment, a seamless covering for an article can be achieved by growing and treating an engineered leather on the object to be coated itself. FIG. 6 shows a cross section of a steering wheel undergoing the cell growth process. The mold provides a uniform space for the cell paste to grow into and create an engineered leather. A seamless covering creates no waste leather and has an aesthetically pleasing appearance.
To create such a seamless covering, an armature 701 is covered in a layer of PU foam 710, which is covered by a substrate layer 715. The substrate layer 715 may be formed as a single piece that has an interlock region 717 where the ends of the substrate layer meet to form a cohesive whole after placement over the PU foam layer. The substrate layer is a biocompatible surface which encourages adhesion of cells and/or ECM.
Cell paste 730, which may optionally be in the form of sheets or strips, is posited upon the substrate layer 715. Then mold 750 is placed around the entire armature assembly. The mold 750 has a top portion 752 and a bottom portion 754 that come together to create a closed mold configuration which has a space therein for cell growth. The cells are maintained as usual with fresh media supplied as necessary, and when the engineered leather has attained the proper thickness, the mold is removed and the leather is treated in situ. This allows for an entirely seamless covering for the article.
In some cases where the leather is grown for a substantially flat surface, such as for covering a tongue or adjustable turning loop of a seat belt assembly, the mold may simply be a flat plate on which the leather is cultured. In such a case the mold itself can be made of a suitable material which has an appearance similar to the components of the automobile interior, and fixed to the portion of the car to be covered, such as by gluing, snapping into place, or any other means. This would prevent a step of dislodging the engineered leather from the substrate upon which it was grown, minimizing the chances of tearing or deformation.
Referring now to FIG. 7A-7C, other components of an automotive interior that can be covered with a cultured leather are shown.
FIG. 7A-7B show a driver-side airbag cover 800 having a substrate layer 815 which is set over a base member 822, or alternatively an airbag cover in which the substrate layer and base member are molded as a monolithic assembly. A leather covering 830 can be engineered to have slits 803 within it at the points where the airbag, upon deployment, would inflate. The leather could be cultured as multiple pieces for each disconnected portion of the airbag surface, or could be formed as a single preformed piece having very thin breakable portions which are configured to tear when the airbag inflates and deploys.
FIG. 7C illustrates a seat belt assembly 840. Because the portions of a seat belt assembly which could be covered in leather are small, at present such coverings are not made because it can be hard to work with such small pieces of leather. However, a cultured leather in a properly-shaped mold could facilitate the creations of such coverings. Components of a seatbelt that could be covered in an engineered leather include but are not limited to a pushbutton, an adjustable turning loop 861, a tongue 863, a D-ring, or a buckle assembly 865. In the case of small articles like these seat belt components, as well as a seat belt buckle pushbutton or a cover for a gear shift handle, an engineered leather can optionally be grown directly on the article itself for increased ease in handling.
Further components of an automobile interior could also have molds designed for them such that an appropriate leather covering could be cultured. These components include gearshifts, door panels, seats, glove box exteriors, dashboard enclosures, and the like.
Referring now to FIG. 8A-8C, a variety of molds for culturing an engineered leather are illustrated. Such molds are useful in that they do not directly correlate to a particular article to be covered by the generated engineered leather, but instead provide a preshaped leather that can be used in a variety of contexts. For instance, a cylindrical mold can have a surface upon which a leather can be cultured. The mold may have a concave surface for cell growth, or a convex surface for cell growth. It may be a mold of one-piece construction, or two-piece construction, or the mold may be made up of more than two pieces. The mold will have an opening through which a cell paste can be applied to the cell growth surface of the mold, and which will allow for extraction of the engineered leather after culturing is complete.
FIG. 8A illustrates a mold 901 of single-piece construction. This mold has an inner concave surface 902 upon which a cell aggregate can be placed for culturing. The resultant leather will have a substantially cylindrical shape and can be treated and then cut to the desired length for use in a covering application. FIG. 8B shows a two-piece mold 910 comprising an inner, solid cylinder 911, and an outer, hollow cylinder 913. The positioning of inner cylinder 911 within the lumen 914 of outer cylinder 913 creates a cell growth space within lumen 914. A cell aggregate can be placed on convex inner cylinder surface 912. The extent of proliferation and therefore the dimensions of the resultant leather will be constrained by the inner surface of outer cylinder 913. Finally, FIG. 8C shows a semicylindrical mold 920 having a concave inner surface 921. In one embodiment, cells can be grown on the surface of one of these semicylindrical molds to form a leather with a semicylindrical shape. In another embodiment, two semicylindrical molds 920 can be placed in contact with one another to form a fully cylindrical mold with the result of a cylindrical cultured leather.
In another embodiment, the engineered leather can be grown in trays that represent the two-dimensional surface of an object to be covered thereby. The final assembly steps, such as sewing or bonding of the engineered leather, then provides the three-dimensional finish.
The leather can be removed from the mold, tanned and treated in any number of postprocessing steps, including dyeing, and stored for later use in any application that can use a substantially cylindrical piece of leather in a downstream application. Growth in the three-dimensional, substantially cylindrical configuration allows for basal structures such as ECM to form in such a way that can strengthen the preshaped engineered leather and help it keep its shape. An engineered leather created in this way can not only be cut to the correct length after storage but also to a desired thickness as necessary.
While the materials and methods of the invention have been described above with reference to certain specific embodiments thereof, it is to be clearly understood that these embodiments have been given for purposes of illustration only and are not intended to be limiting. The scope of the invention is bounded only by the scope of the claims which are set out hereafter.

Claims

What is claimed is:

1. A covering for an article, the article having an outer surface, the covering comprising at least one layer of at least one type of engineered leather, the engineered leather having been cultured on a surface of a preconstructed mold, the mold having similar dimensions to the article to be covered.

2. The covering of claim 1 wherein the mold has an top portion and a bottom portion, a cell growth space being defined between the top portion and the bottom portion, the engineered leather being cultured in the cell growth space and being preshaped therein.

3. The covering of claim 2 wherein the article is a portion of an automobile interior.

4. The covering of claim 3 wherein the article comprises a steering wheel.

5. The covering of claim 3 wherein the article comprises an airbag cover.

6. The covering of claim 3 wherein the article comprises a portion of a safety belt assembly.

7. The covering of claim 6 wherein the article comprises a buckle assembly of a safety belt assembly.

8. The covering of claim 1 wherein the covering comprises two or more types of engineered leather.

9. The covering of claim 1 wherein the covering undergoes a tanning process.

10. A method of covering an article with at least one layer of at least one type of engineered leather comprising the steps of:

providing a mold having a top portion and a bottom portion;

providing a cell aggregate and placing the cell aggregate on the bottom portion of the mold;

providing a quantity of tissue culture medium to the cell aggregate;

placing the top portion of the mold over the cell aggregate;

placing the mold in a chamber adapted to allow for cell growth;

allowing the cells to grow until they form an engineered leather within the mold; and

processing the leather to form a covering for an article.

11. The method of claim 10 wherein the cell aggregate comprises epithelial cells.

12. The method of claim 10 wherein the cell aggregate comprises a cell paste.

13. The method of claim 10 wherein the cell aggregate comprises at least one elongated sheet of cells.

14. The method of claim 10 wherein collagen is exogenously supplied to the cell aggregate.

15. The method of claim 13 comprising a plurality of elongate sheets of cells comprising a first sheet of cells and a second sheet of cells, the second sheet of cells being posited over the first sheet of cells, a layer of collagen being provided between the first sheet of cells and the second sheet of cells.

16. The method of claim 10 wherein the cell aggregate is formed from a skin punch from at least one donor animal.

17. The method of claim 10 wherein the processing step comprises tanning.

18. A method of forming a preshaped engineered leather for covering an article with at least one layer of at least one type of engineered leather comprising the steps of:

providing an article having an outer surface;

providing a mold having an inner surface for growing cells;

providing a cell aggregate and placing the cell aggregate on the inner surface of the mold and on the outer surface of the article;

providing a quantity of tissue culture medium to the cell aggregate;

placing the article in a chamber adapted to allow for cell growth;

allowing the cells to grow until they form an engineered leather within the mold and on the surface of the article; and

removing the mold.

19. The method of claim 18 wherein the preshaped engineered leather defines a seamless covering for the article.

20. An engineered leather having a portion which is cylindrical in shape formed by the steps of placing a cell paste on a cell-growth surface of a substantially cylindrical mold, placing the mold in an incubator, permitting cell growth until a substantially cylindrical leather is formed, removing the substantially cylindrical leather from the mold, and treating the leather.