MXPA00011695A - Vehicle headliner comprised of a thermoformable thermoplastic foam sheet - Google Patents

Abstract

A vehicle having an improved headliner. The headliner comprises a thermoformed core layer. The core layer comprises an extruded thermoplastic foam and optionally one or more adjacent layers of a substantially non-foamed thermoplastic. The core layer is substantially free of thermoset materials and preferably free of glass or fiberglass mattes or scrim. A decorative layer such a felt layer or a fabric layer is preferably laminated to the core layer. The headliner is substantially resistant to sagging and able to substantially maintain its thermoformed shape when installed in the vehicle. There is also a process for assembling or making a headliner and installing it in a vehicle.

Description

ROOF LINING OF VEHICLE THAT CONSISTS OF A THERMOPLASTIC FOAM SHEET, THERMOFORMABLE BACKGROUND OF THE INVENTION The present invention relates to a vehicle roof liner having a thermoformed core layer, which consists of an extruded thermoplastic foam. The central layer and the roof lining are able to substantially maintain their shape and contour, when they are installed in a vehicle, even at elevated temperatures. Roof linings are laminated structures that are applied to the lower sides of the roofs of the passenger compartment in vehicles. The roof linings serve a variety of purposes, including: cushioning, aesthetics, thermal insulation and sound insulation. The roof linings used in commercially produced vehicles are relatively complex and highly engineered, due to the physical demands and the environmental conditions to which the roof linings are exposed. The roof lining must have enough rigidity to prevent it from being pulled down due to gravity; but it must be sufficiently foldable to allow fabrication and / or thermoforming and installation. The roof lining can also be a component of a general impact protection system, which provides some degree of cushioning in the event of sudden contact with an occupant in the passenger compartment. The roof lining must also be able to withstand the elevated temperatures associated with the vehicle's exposure to solar heat. The roof lining must also be capable of being formed to a desired shape, configuration or contour. The liners currently used are typically formed commercially with multiple layers of polyurethane foam and glass / fiberglass batts or mats adhered with polyurethane adhesives and pressed together under heat to a desired shape and contour. Felt or cloth is typically applied to the roof lining on the surface that is to face the interior of the passenger compartment. Representative liners include those described in U.S. Patent Nos. 5,460,870, 5,486,256, 5,582,906 and 5,670,211, which are incorporated herein by this reference. The disadvantages of the current commercial roof linings are many. They are costly due to expensive component materials and complicated manufacturing methods and processes. Thermoforming adhesives such as polyurethane adhesives are expensive and require several steps for the application and methods and processes of healing. The fabric or glass batting, fiberglass, carbon or other materials in fibrous form, which serve as reinforcement, as well as the sheets of polyurethane foam, must also be mutually dispersed in stratified arrangement together with the thermosetting adhesives.

Aionally the component materials and the finished roof liner product are usually difficult if not impossible to recycle efficiently. It would be convenient to have a roof lining consisting of less expensive component materials and that could be assembled through a manufacturing process that was less complex and less expensive. It would also be convenient to have a roof lining that offers functional aspects and attributes similar to those provided by the roof linings that use thermosetting materials and cloth or reinforcing wag. It would also be convenient for the roof lining and / or its component materials to be easily recyclable.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, there is a vehicle having an improved roof lining. The vehicle has a passenger compartment and a roof above the passenger compartment. The roof lining is located adjacent to the underside of the roof. The roof liner comprises a thermoformed central layer. The core layer comprises an extruded thermoplastic foam and, optionally, one or more adjacent layers of a substantially unfoamed thermoplastic. The core layer is substantially free of thermosetting materials and is preferably free of mats or glass batts / fiberglass. The central layer is substantially resistant to upsetting and capable of substantially maintaining its thermoformed shape when the roof lining is installed in the vehicle. Preferably a decorative layer, such as a felt layer or a fabric layer, is laminated to the central layer. Also according to the invention there is a process for assembling or forming a roof liner and installing it in a vehicle. The process comprises: a) providing a thermoformable core layer, comprising an extruded thermoplastic foam and, optionally, one or more adjacent layers of a substantially unfoamed thermoplastic, where the core layer is substantially free of thermosetting materials, is substantially resistant to bagging and capable of substantially maintaining its shape when the roof liner is installed in the vehicle; b) thermoforming the central layer, by application of heat and mechanical pressure, to form the roof lining; c) install or apply the roof lining adjacent to the underside of the roof. It is preferred to laminate a decorative layer to the surface of the central layer that will face towards the interior of the passenger compartment. The decorative layer can be laminated to the central layer either before or after the thermoforming of the central layer.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a fragmentary perspective view, partially in section, of a vehicle having a roof lining. Figure 2 is a side view of the cutout of Figure 1, where the roof and the roof lining of the vehicle are shown.

Figure 3 is a fragmentary perspective view of a roof of a vehicle having a roof lining, where the roof lining is shown trimmed. Figure 4 is a fragmentary perspective view of a roof of a vehicle having a roof lining, where the roof lining is shown in cut-away form. Figure 5 shows a portion of a roof liner having a foamed portion and unfoamed portions. Figures 6 to 11 illustrate various configurations of a portion of a roof lining assembly.

DETAILED DESCRIPTION OF THE INVENTION The roof liner provides many advantages not known in the art with respect to a single roof liner. These advantages are largely related to the thermoformable core layer present in the roof lining. These advantages include the following: the roof lining is easily thermoformable to a desired shape, configuration or contour; the roof lining is sufficiently rigid to prevent bagging and substantially maintain its shape, even when exposed to high temperatures, such as those commonly found in vehicles in hot weather, and / or in direct sunlight conditions; the liner preferably consists of relatively inexpensive and recyclable thermoplastics. The lining offers good shock absorbing properties against the head, and exhibits good acoustic and thermal absorption. The core layer comprising the thermoplastic foam of the present invention provides significant advantages over other foam layers taught in the prior art as useful in roof linings. U.S. Patent No. 5,670,211 describes liners having flexible or semi-rigid foam sheets of polyurethane foam, which are processed and formed into a roof liner with polyurethane adhesives. The patent also discloses that polyurethane foam can be substituted with other sheets of PPO foam, expanded polystyrene and expanded polypropylene. The core layer in the present invention is advantageous with respect to the teachings of the patent, in that it is substantially free of thermosettable adhesives, and can be recycled more easily. The core layer comprising the extruded thermoplastic foam is also thermoformable more easily than the polyurethane foam and is typically stronger for a given density than the expanded (globule) foams and exhibits greater resistance to thermal distortion than the foams of polystyrene. US Pat. No. 3,637,458 discloses very thin extruded polypropylene foam sheets, described as useful in the list of laundry applications, including a top liner. The patent does not teach in terms of the structure of said upper liner nor the function of the polypropylene foam sheet described therein. The foams can serve different functions in a roof lining, such as providing structure and mechanical operation, or as a cushion support for a layer of decorative fabric. U.S. Patent 5,536,793 discloses a polyester foam described as being useful in many applications, including a roof liner. The teachings of this patent are deficient for the same reasons as those of US Pat. No. 3,637,458. The figures illustrate embodiments of the present invention. In Figure 1 the vehicle 10 has a roof 12, a passenger compartment 14 and a roof liner 16. Figure 1 shows a cutout along a circular dotted line 2-2, corresponding to the side view in section which appears in Figure 2. Figure 2 shows the roof 12 having a roof liner 16 adhered to or fixed thereto. The liner 16 comprises a layer 20 of extruded thermoplastic foam, conventional, an adhesive layer 22 and a fabric layer 24. Figure 3 shows another embodiment of a roof / roofliner combination. In Figure 3 there is a roof liner 30 adhered to or f to a vehicle roof 32. The roof liner 30 comprises an extruded thermoplastic foam 34 of coalesced yarns and a fabric layer 36. In the roof lining 30 the coalesced yarns or strands are oriented generally vertically and are generally perpendicular to the plane of the roof. roof 32. Figure 4 shows another embodiment of a roof / roof liner combination. In figure 4 there is a liner 40 adhered or f to a vehicle roof 42. The liner 40 comprises an extruded thermoplastic foam 44 of coalesced strands or threads, and a fabric layer 46. In the roof lining 40 the strands or threads are oriented generally horizontally, and are generally parallel to the plane of the roof 42. he knows in the art adhesives that can be used to adhere the various layers of the roof lining together or the roof lining to the roof of the vehicle. Useful adhesives include thermoset adhesives such as polyurethane resins and epoxies, as well as thermoplastic adhesives, such as polyethylenes, polypropylenes, ethylene copolymers, propylene copolymers and the like. Useful adhesives are taught in U.S. Patent Nos. 5,460,870 and 5,670,211. The adhesives can be applied by any means known in the art, such as spraying, coating or in the form of a film. The preferred adhesives are thermoplastic because of their lower cost and their potential for recycling. The presence of an adhesive is not critical to the present invention. The foam can be closed cells or open cells. The content of open cells is determined according to ASTM D2856-A. Closed cell foams provide advantages of better thermal insulation capacity and better elasticity, and open cell foams provide advantages of better acoustic insulation, better dimensional stability and better heat transfer during thermoforming. The thermoplastic foam preferably has a density, before thermoforming, of about 16 to 200 and, more preferably, about 6 to 80 kilograms per cubic meter. The foam has a preferable average cell size that is approximately between 0.1 and 5.0 and, preferably, approximately between 0.2 and 3.0 millimeters, in accordance with ASTM D3576. The indicated foam density and variations in cell size are generally of the nature for thermoplastic foams. The highly preferred density and highly preferred cell size scales will vary depending on the composition of the foam and the desired physical properties. For example, a stiffer foam can usually be prepared by increasing the density or size of the cells. Particularly suitable foams are those of propylene polymers, polyesters and polyamides, which have a density before thermoforming of about 16 to about 160 kilograms per cubic meter and, preferably, about 24 to 100 kilograms per cubic meter. Preferably the thermoplastic foam is extruded as a unitary structure, but it can also be formed by laminating together two or more relatively thin thermoplastic foam sheets, by any means known in the art, such as by thermal welding or by adhesive layers. The foam must be resistant to thermal distortion and be dimensionally stable at elevated temperatures such as those commonly found on the roof of a vehicle due to solar heat. The foam preferably exhibits a dimensional stability of about 5 percent or less, more preferably, about 1 percent or less, with respect to both expansion and shrinkage, conforming to SAE 883. Foams can be made from any size or configuration in cross section, such as a sheet or a foam plate. Particularly useful foams are those that have a smaller dimension in cross section (thickness) of 1. 5 millimeters or more, and preferably 3 millimeters or more. One or more layers of a decorative material, such as felt or cloth, can be applied to the surface of the roof lining facing the interior of the passenger compartment or the interior cabin, for aesthetic appearance. The layer may be of any type known in the art. The employees are very typically commercially woven or felted fabrics. Useful fabrics include those of woven fibers of polyester, nylon and polypropylene. It is preferable that the felt or fabric layer consist of the same or similar polymeric material as the foam. The felt or fabric layer can be adhered to the foam by means known in the art, such as thermal welding, adhesive or liquid films or adhesive coatings. A preferred decorative layer is a woven fabric of thermoplastic fibers, thermally welded to the core layer without the benefit of the adhesives. Thermal welding refers to heating the fabric layer to a degree such that the fibers become sticky or adherent and are able to adhere to the core layer, without the benefit of an adhesive. A fabric layer can be thermally welded to a core layer if it is applied to the core layer during thermoforming or when the core layer is otherwise at an elevated temperature. A preferred roof lining consists entirely of recyclable materials. Useful recyclable materials include propylene polymers, such as polypropylene, high density polyethylene, polyesters, such as polyethylene terephthalate, and polycarbonates. A highly preferred roof liner consists entirely of recyclable materials, of similar composition, so that they can be recycled together. For example, a roof liner may consist of any of the following: a laminated structure of a propylene polymer foam and a woven polypropylene fabric layer; a laminated structure of polyethylene terephthalate foam and a woven fabric layer of polyethylene terephthalate; or a polyamide foam (nylon) and a layer of polyamide fabric. If desired, different recyclable materials may be used together, such as the following: a) a laminated structure of a propylene polymer foam and a woven fabric layer of a polyester or a polyamide; and b) a laminated structure of a polyester foam and a woven fabric layer of polypropylene or a polyamide. The foam is easily thermoformable to a desired shape, configuration or contour. Typically, the foam and the rest of the roof liner have substantially the same shape, configuration or contour as the roof of the vehicle, since the liner is placed on the underside of the roof. The term "thermoformable" means that the foam may be thermoformed or otherwise configured under heat and mechanical pressure, by any conventional means known in the art, to a different shape or contour. Typically the foam is provided in the form of a substantially flat sheet or plate, and pressed under heat and pressure to form a contoured sheet, similar in shape and shape to the roof of the vehicle below which it is to be placed. If desired, a decorative layer, such as a layer of thermoplasic woven fabric, can be thermally welded to the foam during the thermoforming process. The physical properties and thermal resistance of the foam can be enhanced by forming or inducing the formation of a substantially unfoamed skin on the foam, such as by laminating plastic films or plastic sheets to the foam, coating it with a plastic resin, heating a surface or the surfaces of the foam above its glass transition temperature or melting point, to collapse the cellular structure in the crust or skin, or a combination of any of the foregoing. The film, sheet or coating may consist of any thermoplastic resin or thermosetting resin known. Useful thermoplastic resins include those described above with respect to those composing the foam, and thermosetting resins include polyurethanes and epoxy resins. The roof lining can be applied to the underside of the vehicle roof by any means known in the art, such as by adhesion, or by mechanical fastening means. The mechanical means include: fasteners, side moldings and upper light assemblies (dome). Useful thermoplastic foams include, but are not limited to, those of propylene polymer, polyester, polyamide, polycarbonate, high density polyethylene, chlorinated polyethylene, polyphenylene oxides, mixtures of polyphenylene and polystyrene oxides, propylene / ethylene copolymers, thermoplastic polyurethanes, mixtures of EPDM and polyethylene, blends of polypropylene and EPDM, blends of polypropylene and ethylene / styrene copolymers. The ethylene / styrene copolymers and the foams containing them are taught in U.S. Patent No. 5,460,818, which is incorporated herein by this reference. Preferred foams include propylene polymer foams and polyester foams. most preferred foams include polypropylene foams, propylene / ethylene copolymer foams of 95/5 to 99.5 / 0.5 weight ratio of monomers; and polyethylene terephthalate foams. A highly preferred foam for the core layer is an extruded propylene polymer foam. Suitable propylene polymer materials include the homopolymers of propylene (polypropylene) and the copolymers of propylene and copolymerizable ethylenically unsaturated comonomers. The propylene polymer material may additionally include non-propylene polymers. The propylene polymer material may consist solely of one or more propylene homopolymers, one or more propylene copolymers, a mixture of one or more of each of propylene homopolymers and copolymers, or mixtures of any of the foregoing with a polymer not propylene Regardless of the composition, the propylene polymer material comprises more than 50 weight percent and, preferably, about 70 weight% or more of monomeric propylene units. Suitable monoethylenically unsaturated comonomers include: olefins, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, acrylic acid, itaconic acid, maleic acid, maleic anhydride, and the like. The propylene copolymer preferably comprises about 45 percent or less, by weight, of the ethylenically unsaturated comonomer. Suitable non-propylene polymers in the propylene polymer material include high, medium, low and linear density polyethylenes; polybutene-1, ethylene / acrylic acid copolymer, ethylene / vinyl acetate copolymer, ethylene / propylene copolymer, styrene / butadiene copolymer, ethylene / styrene copolymer, ethylene / ethyl acrylate copolymer, ionomer and the like. Particularly useful propylene copolymers are those copolymers of propylene and one or more non-propylene olefins. The propylene copolymers include the random, block or graft copolymers of propylene and an olefin selected from the group consisting of ethylene, 1-olefins of 4 to 10 carbon atoms and dienes of 4 to 10 carbon atoms. The propylene copolymers also include random terpolymers of propylene and 1-olefins, selected from the group consisting of ethylene and 1-olefins of 4 to 8 carbon atoms. In terpolymers having ethylene and 1-olefins of 4 to 8 carbon atoms, the ethylene content is preferably 45 percent or less, by weight. The 1-olefins of 4 to 10 carbon atoms include the linear and branched 1-olefins of 4 to 10 carbon atoms, such as, for example: 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene , 1-hexene, 3,4-dimethyI-1-butene, 1-heptene, 3-methyl-1-hexen and the like. Examples of dienes of 4 to 10 carbon atoms include: 1,3-butadiene, 1,4-pentadiene, soprene, 1,5-hexadiene, 2,3-dimethyl-1,3-hexadiene and the like. Also, as used herein, the propylene polymer material has a melt flow rate of between about 0.05 and 50, and preferably between 0.1 and 20, according to ASTM D1238, condition L. Polymer resins of Preferred propylene are those propylene resins which are branched or slightly interlaced polymeric materials. Branching (or light entanglement) can be obtained by methods that are generally known in the art, such as light chemical branching / interlacing or by irradiation. One such resin, which is prepared as a branched / slightly interlaced polypropylene resin, before using the polypropylene resin to prepare a finished polypropylene resin product, and the method for preparing said polypropylene resin, are described in the patent No. 4,916,198, which is incorporated herein by this reference. Another method for preparing branched / slightly interlaced polypropylene resin is to introduce chemical compounds into the extruder, together with the polypropylene resin, and to allow the light branching / interlacing reaction to take place in the extruder. U.S. Patent No. 4714,716 illustrates this method and is incorporated herein by this reference. Useful extruded propylene polymer foams can be found in U.S. Patent Nos. 5,348,795, 5,527,573 and 5,567,742, which are incorporated herein by this reference. Extruded, useful polyester foams, including polyethylene terephthalate (PET) foams, can be found in U.S. Patent Nos. 5,000,991, 5,234,640 and ,536,793, which are incorporated herein by means of this reference. The foams can be formed from other useful thermoplastics, such as high density polyethylene, chlorinated polyethylene, TPO mixtures of EPDM rubbers (ethylene / propylene / diamine copolymers) and polyethylene. The useful thermoplastic foams are preferably not interlaced, but may be slightly interlaced. The term "non-interlocked", however, includes the slight degree of entanglement that occurs naturally without the use of interlacing agents or radiation. Non-interlaced foams contain less than 5 percent gel according to ASTM D2765.-84, Method A. The slightly interlaced foams contain 5 to 15 percent gel, according to ASTM D2765-84, Method A. The blowing agent it can comprise any known in the art, such as chemical blowing agents and physical blowing agents of organic and / or inorganic composition. Suitable, useful inorganic blowing agents include carbon dioxide, nitrogen, argon, water, air, nitrogen and helium. Suitable organic blowing agents include aliphatic hydrocarbons having from 1 to 9 carbon atoms and halogenated aliphatic hydrocarbons having from 1 to 4 carbon atoms. The aliphatic hydrocarbons include: methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane and the like. Also included are alcohols, such as ethanol, methanol and propanol. Among the halogenated hydrocarbons, fluorinated hydrocarbons are preferred. Examples of fluorinated hydrocarbon include: methyl fluoride, perfluoromethane, ethyl fluoride, 1,1-difluoroethane, 1,1,1-trifluoroethane (HFC-143a), 1,1,1-tetrafluoroethane (HFC-134a) , pentafluoroethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, perfluorobutane, perfluorocyclobutane. Chlorocarbons and partially halogenated chlorofluorocarbons, for use in that invention, include: methyl chloride, methylene chloride, ethyl chloride, 1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (HCFC-141b) , 1-chloro-1, 1-difluoroethane (HCFC-142b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC) -124). Fully halogenated chlorofluorocarbons include: trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113), dichlorotetrafluoroethane (CFC-114), chlorheptafluoropropane and dichlorohexafluoropropane. Fully halogenated chlorofluorocarbons are not preferred because of their ozone depletion potential. Chemical blowing agents include: azodicarbonamide, azodiisobutyronitrile, benzenesulfohydrazide, 4,4-oxybenzenesulfonyl-semicarbazide, p-toluenesulfonyl-semicarbazide, barium azodicarboxylate, N, N'-dimethyl-N, N'-dinitrosoterephthalamide and trihydrazinotriazine. The amount of blowing agent incorporated in the polymer melt to form the foam-forming polymer gel is about 0.2 to 4.0, preferably about 0.3 to 3.0, and, most preferably, about 0.5 to 2.50 moles per kilogram of polymer. Thermoplastic foams are generally prepared in extrusion processes, heating a thermoplastic to form a plasticized or molten polymeric material, incorporating in it a physical blowing agent to form a foamable gel, and extruding the gel through a die to form the product of foam. The blowing agent may be incorporated or blended into the plastic melt by any means known in the art, such as with an extruder, mixer, beater, or the like. Before mixing with the blowing agent, the plastic materials are heated to a temperature at or above the glass transition temperature or the melting point of the plastic material. The blowing agent is mixed with the plastic melt at an elevated pressure, sufficient to prevent substantial expansion of the melt and to generally disperse the blowing agent in a homogeneous manner within the melt. Optionally a nucleator is combined in the polymer melt. The feeding speed of the blowing agent and the nucleator is adjusted to obtain a foam of relatively low density and small cell size, which results in a foam having thin cell walls. After incorporating the blowing agent, the foamable gel is typically cooled to a lower temperature to optimally elevate the physical characteristics of the foam product. The gel is then extruded through a die of desired shape, into a zone of lower pressure, to form the foam product. If a chemical blowing agent is used, it is incorporated into the molten polymer material and extruded or transported to a high temperature zone where the agent decomposes to form a gas, usually carbon dioxide. The molten polymer / gas mixture is expanded to form a foam. Other suitable processes for forming the thermoplastic foams are the coalesced foam processes described in U.S. Patent Nos. 4,824,720, 5,348,795, 5,527,573, 5,567,742 and WO 88/06094, which are incorporated herein by this reference. These patents refer to processes for forming open cell and closed cell polyolefin foams, comprising a plurality of extruded strands or profiles, coalesced, using a die containing a multiplicity of holes. The holes are arranged in such a way that the contact between the adjacent streams of the molten extrusion product occurs during the foaming process and the surfaces in contact adhere to each other with sufficient adhesion to result in a unitary structure. The individual strands of coalesced foam must remain adhered in a unitary structure to prevent delamination under the stresses found in the preparation, configuration and use of the foam. The coalesced, extruded strand foam provides the advantage of anisotropic physical properties. Said foams exhibit relatively greater compression resistance and impact resistance in the extrusion direction than in the vertical or horizontal directions. When the strands are oriented vertically, as in the roof lining of Figure 8, greater impact resistance is observed to the blows to the head, for a foam of a given density, in comparison with conventional thermoplastic foams, of unitary structure , extruded through a conventional slot die. WO 88/06094 relates to coalesced strand foam extrusion processes, where certain orifices within a multiple hole extrusion die can be blocked or sealed, so that coalesced strand foams having continuous longitudinal channels can be produced, of relatively large diameter or relatively large dimension. The coalesced strand foams, which have relatively large channels as mentioned, can be used in the roof lining, in the manner shown in Figure 4, so that channels can be formed for electrical wiring or ventilation ducts, cold air or hot, from the front of the passenger compartment to the rear or rear of the compartment, if desired. U.S. Patent No. 4,323,528, incorporated herein by reference, refers to the formation of poly-define foams by an extrusion process that accumulates. The process comprises: 1) mixing a thermoplastic material and a blowing agent to form a polymer gel; 2) extrude the gel to a retention zone, maintained at a temperature and pressure that does not allow the mixture to foam; the retention area has a die that defines a hole that opens towards a zone of lower pressure, in which the gel foams, and a door that can be opened, which closes the die orifice; 3) periodically open the gate; 4) substantially applying a mechanical pressure concurrently by means of a movable piston, on the gel, to eject it from the retention area, through the die orifice, towards the zone of least pressure; and 5) allowing the ejected gel to expand to form the foam. The physical strength of the foam can be increased by incorporating relatively thin, substantially non-foamed plates or profiles into the foam portion of the roof liner. This can be achieved by any suitable method, for example, extruding the desired plate / profile and combining the foam directly using extrudates or plastic fusions, with or without blowing agent, which are transported through different orifices within the extrusion die, and which is allowed to coalesce to form a plate / profile and combine the foam having foamed and unfoamed portions of resin. Another method is to extrude the foam under such conditions that it makes contact with the plates or the profile when extruded, thereby forming the desired combination. In the extrusion section of the foam, the plates or unfoamed resin portions may adopt a regular or irregular pattern. The plates or profiles can be intersecting or non-intersecting, one with respect to the others. The possible patterns of section for the profiles or plates nonfoamed, inside the foam, include the patterns in the form of honeycomb, circular, rectangular or diagonal grid. Figure 4 shows a plate / profile and foam combination having a rectangular grid pattern having foamed portions 51 and unfoamed portions 52. It is also possible to manufacture extruded structures having foamed and unfoamed portions, cutting a foam with a hot wire and subsequently reattaching or coalescing the cut foam portions, so that they are thermally welded together. It is preferred that thermal welding occurs immediately after the foam has been cut with the hot wire. The application of heat to the foam collapses the cellular structure of the foam adjacent to the wire and creates an unfoamed plate or profile within the foam, after which the cut parts of foam coalesce. It is also possible to manufacture structures having foamed and unfoamed portions, by laminating profiles or foamed and non-foamed layers together, in an alternating configuration, to form a unitary structure. Said profiles or layers could be laminated to one another either by thermal welding or by adhesion. Additionally a nucleating agent can be added in the foaming process, in order to control the size of the foam cells. Preferred nucleating agents include inorganic substances, such as calcium carbonate, talc, clay, titanium dioxide, silica, barium sulfate, calcium stearate, barium stearate, diatomaceous earth, mixtures of citric acid and sodium bicarbonate, and the like. The amount of nucleating agent employed may vary from about 0.01 to 5 parts by weight per hundred parts by weight of a polymer resin. The preferred scale is 0.1 to 3 parts by weight. It is also possible to add various additives to the foam and in the foaming process, such as pigments, antioxidants, acid scavengers, ultraviolet absorbers, fire retardants, processing aids, extrusion aids and the like. The physical properties and thermal resistance of the foam can be increased by adding particles or fibers of organic or inorganic materials in the form of fillers. Such particulate materials or fibers could be added to the foam-forming compositions during manufacture. Useful materials include: carbon black particles, clay particles, carbon or graphite fibers, polypropylene fibers, polyester fibers and nylon fibers; glass fibers and acrylonitrile fibers. The physical properties and thermal resistance of the foam can also be increased by laminating foams or unfoamed film / foil layers containing said particles and / or fibers to the foam. The fibers can be of any length: short (fibrils) or long. They can be randomly dispersed or woven or placed together in the form of a fabric or a prepreg. Adhesives known in the art can be used to adhere various layers of the roof liner together or the roof lining to the car roof. Useful adhesives include thermoset adhesives, such as polyurethane resins and epoxy resins and thermoplastic adhesives, such as polyethylenes, polypropylenes, ethylene copolymers, propylene copolymers and the like. Useful adhesives are taught in U.S. Patent Nos. 5,460,870 and 5,670,211. The adhesives can be applied by any means known in the art, such as by spraying with coating or in the form of a film. The preferred adhesives are thermoplastic due to their lower cost and their recycling potential. The presence of an adhesive is not critical in the present invention. One or more layers of decorative material, such as a felt or cloth, may be applied to the surface of the roof liner facing the interior of the passenger compartment or interior cabin for aesthetic reasons. The layer can be any type of layer known in the art. The employees very typically in the trade are felts or woven fabrics. Useful fabrics include those of woven fibers of polyester, nylon and polypropylene. It is preferred that the felt or fabric layer consist of the same or similar polymeric material as the foam. The felt or fabric layer can be adhered to the foam by any means known in the art, such as heat sealing, adhesive or liquid films or adhesive coatings. A preferred decorative layer is a woven fabric of thermoplastic fibers thermally welded to the core layer without the benefit of the adhesives. Thermal welding refers to heating the fabric layer to a degree such that the fibers become tacky or adherent and are able to adhere to the core layer, without the need for an adhesive. A layer of fabric can also be thermally welded to a core layer if it is applied to the core layer during thermoforming, or when the core layer is at an elevated temperature. A preferred roof lining consists entirely of recyclable materials. Useful recyclable materials include propylene polymers, such as polypropylene; high density polyethylene, polyesters, such as polyethylene terephthalate and polycarbonates. A highly preferred roof liner consists entirely of recyclable materials of similar composition, so that they can be recycled together. For example, a roof liner may comprise any of the following: a laminated structure of a propylene polymer foam and a woven polypropylene fabric layer; a laminated structure of a polyethylene terephthalate foam and a woven fabric layer of polyethylene terephthalate; or a polyamide foam (nylon) and a layer of polyamide fabric. If desired, different recyclable materials may be employed, such as the following: a) a laminated structure of a propylene polymer foam and a woven fabric layer of a polyester or a polyamide; and b) a laminated structure of a polyester foam and a woven fabric layer of polypropylene or a polyamide. The foam is easily thermoformable to a desired shape, configuration or contour. Typically the foam and the rest of the roof liner have substantially the same shape, configuration or contour as the roof of the vehicle, since the roof lining is placed on the underside of the roof. The term "thermoformable" means that the foam can be thermoformed or otherwise configured under heat and mechanical pressure, by any means known in the art, to a different shape or contour. Typically, the foam is provided in the form of a substantially flat sheet or plate, and pressed under heat and pressure to form a contoured sheet of similar configuration and contour to the roof of the vehicle below which it is to be disposed. If desired, a decorative layer, such as a layer of thermoplastic woven fabric, can be thermally welded to the foam during the thermoforming process. The physical properties and thermal resistance of the foam can be increased by forming or inducing the formation of a substantially unfoamed skin or crust, in the foam; such as by laminating plastic films or plastic sheets to the foam, coating it with a plastic resin, heating the surface or surfaces of the foam below its glass transition temperature, or the melting point, to collapse the cellular structure in the skin or scab; or a combination of any of the foregoing. The film, sheet or coating may comprise any thermoplastic resin or thermosetting resin known. Useful thermoplastic resins include those described above with respect to those composing the foam, and useful thermosetting resins include polyurethanes and epoxy resins. The roof lining can be applied to the underside of the roof of a vehicle, by means known in the art, such as adhesion or fixing it by mechanical means. The mechanical means include staples, side moldings and upper light assembly. The term "vehicle" includes those which are known in the field as automobiles, trucks, recreational vehicles, sports service vehicles, airplanes, trains and boats. Figures 6 to 10 illustrate portions of various different roof liner configurations. Figure 6 shows two sheets of foam 61 and 62, consisting of foam strands having a vertical orientation, a sheet 63 of foam-supported fabric, and layers of adhesive film 64 and 65. In a preferred embodiment, the lining of the roof contains the second foam sheet 62 only in certain locations of the roof lining, where additional energy absorption capacity is desired, such as along the sides of the roof lining, closer to the passenger doors; but at any other point it consists of a single sheet of foam, in order to minimize the thickness of the lining at those other sites. Adhesive film layers 64 and 65 can be used to adhere the fabric and foam layers and to increase the overall stiffness of the roof liner. If desired, the film layers and the layers of fabric and foam adhered to each other by any medium gold, such as by thermally welding the foam layers together, and using a liquid fabric adhesive that bind the layer, can be omitted. of foam adjacent to it. Figures 7 to 9 show several ways in which two layers of foam can be oriented within the roof lining. The upper foam layers 71, 81 and 91, in these configurations, consist of strand foams that are positioned so that the strands are perpendicular to the vehicle roof, so that maximum energy absorption is obtained. The lower foam layer is shown as a layer of strand foam 72 having strands perpendicular to the roof, a strandless foam 82 and strand foam that is positioned so that the strands are perpendicular to the vehicle roof 92. In In this embodiment, the foam layers can be fixed to each other by suitable means, such as by means of the use of adhesives, adhesive films or by hot welding to join them. Figure 10 shows a portion of the foam of the roof liner as a single piece of strand foam, which has been cut or molded to the desired shape, having thinner portions and thicker portions; the thicker portions being located along the side of the roof lining closest to the side doors of the passenger. Figure 11 shows a portion of a roof liner having three layers of strand foam, 96, 97 and 98; providing the third layer with additional energy absorption capacity.

EXAMPLES Foams were prepared that could be thermoformed and manufactured to form roof linings suitable for installation in vehicles, in the examples that follow.

EXAMPLE 1 A sheet of extruded polypropylene foam was produced. The apparatus for producing the foam consisted of an extruder, a mixer, a cooler and an annular extrusion die, in series. The polymer was fed in granular form to the extruder, where it was mixed with additives to form a polymer melt. The polymer melt was transported to the mixer, where a blowing agent was incorporated under pressure to form a foamable gel. The foamable gel was transported to the die, where it expanded out of the annular orifice, around a mandrel, to form a tubular foam sheet product. Then the tubular sheet was cut to form a flat sheet. The propylene polymer resin was 98/2 polypropylene resin (homopolymer [Montell HMS resin PF-814] The blowing agent was 8 pph (parts per hundred parts isobutane, based on the weight of the polymer), isobutane The additives used were 0.2 pph of talc (nucleating agent), 0.1 pph of Irganox 1010 (antioxidant) and 0.1 pph of Ultranox 626 (antioxidant) The foam had a thickness of 5 millimeters (mm) and a width of 1600 mm; an open cell content of 1.6 percent, a density of 43.2 kilograms per cubic meter (kg / m3) and an average cell size of 1.7 mm.The foam had a foaming index as described in US patent 5,527,573, 5.3 The foam was relatively stiff, it was not bagged when it supported its own weight and was thermoformable.The foam was cut and molded to the desired profile of a vehicle roof lining, and a decorative fabric was adhered to it. in a vehicle, adjacent to the side under the roof of the vehicle, and fixed to it by means of a suitable adhesive.

EXAMPLE 2 Another sheet of extruded polypropylene foam was produced, in the apparatus described in Example 1, with the same content of blowing agent and the same filler, and substantially under the same processing conditions as in Example 1, but with an opening of greater separation in the die, and a speed of stretching to remove it, slower. The foam had a thickness of 9 mm and a width of 1600 mm; an open cell content of less than 2 percent; a density of 38 kg / cm3 and an average cell size of 1.7 mm. The foam had a foaming index value, as described in U.S. Patent 5,527,573, of 4.7. The foam was relatively stiff and did not bag when supporting its own weight. The foam was cut and molded to the desired profile of a vehicle roof liner and a layer of a decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle and fixed to it by means of a suitable adhesive.

EXAMPLE 3 Another sheet of extruded propylene copolymer foam was produced in the apparatus described in Example 1, with the same content of blowing agent and filler, and substantially the same processing conditions as in Example 1. The foam had a 7 mm thick and 1600 mm wide; an open cell content of 19 percent and a density of 46.1 kg / m3 and an average cell size of 1.75 mm. The foam had a foaming indicium value, as described in U.S. Patent 5,527,573, of 5.8. The foam was relatively rigid; He did not take off when he bore his own weight, and he was thermoformable. The foam was cut and molded to the desired profile of a vehicle roof liner and a decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle, and fixed to it by means of a suitable adhesive.

EXAMPLE 4 A sheet of extruded polypropylene foam was produced, in the apparatus described in example 1, with the same blowing agent and the same additives, plus the addition of calcium stearate powder for additional nucleation of cells. The polypropylene was fed to the extruder at 449 kg / hour along with 0.42 pph of talcum, 0.3 pph of Ultranox ™ 815P, stabilizer (from GE Specialty Chemicals), 0.3 pph of calcium stearate. Then the plasticized gel mixture was mixed with 3.9 pph of isobutane under pressure; it was cooled to 161 ° C and transported to an annular die, where it was allowed to expand to a region of lower pressure, it was stretched on a 40.64 cm diameter chill mandrel to form a tubular foam sheet product. Then the tubular sheet was cut to form a flat sheet. The foam had a thickness of 7 mm and a width of 1290 mm, an open cell content of 20.4%, a density of 52.9 kg / m3 and an average cell size of 3.6 mm. The foam was relatively stiff, it was not bagged when it supported its own weight and was thermoformable. The foam had a flexural strength at a failure value of 1.21 MPa when tested by the method described in SAE J949, and a foaming factor of 13.6. The foam was cut and molded to the desired profile of a vehicle roof liner, and a decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle, and fixed to it by means of a suitable adhesive.

EXAMPLE 5 Another sheet of extruded polypropylene foam was produced in the apparatus described in Example 1, with the same blowing agent and the same additives, plus the addition of calcium stearate powder for additional nucleation of cells. The polypropylene polymer was fed to the extruder at 626 kg / hour, along with 0.30 pph of talc, 0.21 pph of Ultranox ™ 815P, stabilizer (from GE Specialty Chemicals), 0.3 pph of calcium stearate. The plasticized gel mixture was then mixed with 3.9 pph of isobutane, under pressure; it was cooled to 161.5 ° C and transported to an annular die, where it was allowed to expand towards a region of lower pressure, it was stretched on a 50.8 cm diameter cooler mandrel to form a tubular foam sheet product. Then the tubular sheet was cut to form a flat sheet. The foam had a thickness of 10.9 mm and a width of 1600 mm, an open cell content of 2.2%, a density of 54.5 kg / m3 and an average cell size of 5.2 mm. The foam was relatively stiff, it was not bagged when it supported its own weight and was thermoformable. The foam had a flexural strength at a failure value of 1 MPa when tested by the method described in SAE J949 ^ a foaming factor of 20.3. The foam was cut and molded to the desired profile of a vehicle roof liner, and a layer of decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle and fixed to it by means of a suitable adhesive.

EXAMPLE 6 An extruded foam sheet was produced from a mixture of 75% polypropylene PF-814 from Montell and 25% polyethylene AFFINITY ™ PL-1880 from The Dow Chemical Company. PL-1880 is a polyethylene resin with a melt index value of 1.0 dg / minute, with a density of 0.9020 g / cc and a MO / 12 of 9.0. The foam sheet was made in the apparatus described in Example 1. The polymer mixture was fed to the extruder at 454 kg / hour, together with 0.4 pph talc and 0.3 pph Ultranox ™ 815P, stabilizer (from GE Specialty Chemicals) . The plasticized gel mixture was then mixed with 6.0 pph of isobutane, under pressure; it was cooled to 157 ° C and transported to an annular die, where it was allowed to expand to a region of lower pressure, it was stretched on a 50.8 cm diameter cooler mandrel to form a tubular foam sheet product. The tubular sheet was then opened to form a flat sheet. The foam had a thickness of 7 mm and a width of 1600 mm, an open cell content of 14.4%, a density of 57.7 kg / m3 and an average cell size of 3.4 mm. The foam was relatively stiff, it was not bagged when it supported its own weight and was thermoformable. The foam had a flexural strength, at the failure value, of 0.5 MPa, as tested by the method described in SAE J949, and a foaming factor of 14.0. The foam was cut and molded to the desired profile of a vehicle roof liner, and a layer of decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle and fixed to it by means of a suitable adhesive.

EXAMPLE 7 An extruded foam sheet was produced from a mixture of 75% polypropylene PF-814 from Montell and 25% polyethylene AFFINITY ™ PL-1880 from The Dow Chemical Company. PL-1880 is polyethylene resin with a melt index value of 1.0 dg / minute, with a density of 0.9020 g / cc and a 110/12 of 9.0. The foam sheet was made in the apparatus described in Example 1. The polymer mixture was fed to the extruder at 454 kg / hour, together with 0.4 pph talc and 0.3 pph Ultranox ™ 815P, stabilizer (from GE Specialty Chemicals) . Then the plasticized gel mixture was mixed with 6.0 pph of isobutane, under pressure; it was cooled to 157 ° C it was transported to an annular die, where it was allowed to expand towards a region of lower pressure; it was stretched on a 50.8 cm diameter cooling mandrel to form a tubular foam sheet product. The tubular sheet was then opened to form a flat sheet. The foam had a thickness of 9.8 mm and a width of 1600 mm, an open cell content of 5.8%, a density of 43.3 kg / m3 and an average cell size of 4.5 mm. The foam was relatively stiff, it was not bagged when it supported its own weight and was thermoformable. The foam had a flexural strength, at the failure value, of 0.5 MPa when tested by the method described in SAE J949, and a foaming factor of 13.0. The foam was cut and molded to the desired profile of a vehicle roof liner, and a decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle, and fixed to it by means of a suitable adhesive.

EXAMPLE 8 A sheet of extruded foam was produced from a mixture of 75% polypropylene PF-814 from Montell and 25% polyethylene AFFINITY ™ PL-1880 from The Dow Chemical Company. PL-1880 is a polyethylene resin with a melt index value of 1.0 dg / minute, with a density of 0.9020 g / cc and a 110/12 of 9.0. The foam sheet was made in the apparatus described in Example 1. The polymer mixture was fed to the extruder at 545 kg / hour, along with 0.4 pph of talc and 0.3 pph of Ultranox ™ 815P stabilizer (from GE Specialty Chemicals). The plasticized gel mixture was then mixed with 6.0 pph of isobutane, under pressure; it was cooled to 156 ° C and transported to an annular die, where it was allowed to expand towards a region of lower pressure, it was stretched on a cooling mandrel, 50.8 cm in diameter to form a tubular foam sheet product. The tubular sheet was then opened to form a flat sheet. The foam had a thickness of 14.6 mm and a width of 1600 mm, an open cell content of 3.3%, a density of 41.7 kg / m3 and an average cell size of 3.2 mm. The foam was relatively stiff, it was not bagged when it supported its own weight and was thermoformable. The foam had a flexural strength, at the fence value, of 0.4 MPa, when tested by the method described in SAE J949. The foam has a foaming factor of 9.5. The foam was cut and molded into the desired profile of a vehicle roof liner and a decorative fabric was adhered to it. The roof lining was installed in a vehicle adjacent to the underside of the roof of the vehicle and fixed to it by means of a suitable adhesive.

EXAMPLE 9 The foam sheet of Example 8 was laminated with a 0.04 mm thick multilayer film. The two layer film was made: a) ethylene: acrylic acid / mixture mixture (60/40) of linear low density polyethylene; b) homopolymeric polypropylene. The adhesive layer a), constituted XX% of the thickness of the film. The film was laminated to one side of the foam. After lamination, the film / foam structure was cut to a section of 7.62 by 30.48 cm, and tested for its flexural strength, as in the SAE J949 test. The resulting structure required more than 25 newtons to bend 25.4 mm. The foam has a foaming factor of 9.5. The foam was cut and molded to the desired profile of a vehicle roof liner, and a layer of decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle, and fixed thereto by means of a suitable adhesive.

EXAMPLE 10 The foam sheet of Example 5 was laminated with a multilayer film, 0.04 mm thick, as described in Example 9. The film was laminated to one side of the foam. After lamination the film / foam structure was cut to a section of 7.62 by 30.48 cm, and tested for flexural strength, as in the SAE J949 test. The foam has a foaming factor of 20.3. The resulting structure needed more than 45 newtons to bend 25.4 mm. The foam of example 5 needed 20 Newtons to bend the foam 25.4 mm. The foam was cut and molded to the desired profile of a vehicle roof liner, and a layer of a decorative fabric was adhered to it. The roof lining was installed in a vehicle, adjacent to the underside of the roof of the vehicle and adhered to it by means of a suitable adhesive.

EXAMPLE 11 The foam sheet of Example 7 was laminated with a film of several layers, 0.04 mm thick, as described in Example 9. The film was laminated to one side of the foam. After laminating the film / foam structure was cut to a 7.62 cm by 30.48 cm section, and tested for flexural strength, as in the SAE J949 test. The foam has a foaming factor of 13.0. The resulting structure required more than 14 newtons to bend 25.4 mm. The foam was cut and molded to the desired profile of a vehicle roof liner and a layer of a decorative fabric was adhered to it. The roof lining was installed in a vehicle adjacent to the underside of the vehicle roof, and fixed to it by means of a suitable adhesive.

Claims (32)

1. - A vehicle; the vehicle has a passenger compartment and a roof above the passenger compartment; the vehicle has a roof lining, located adjacent to the underside of the roof; characterized the roof liner because it comprises a thermoformed central layer; the central layer comprises an extruded thermoplastic foam and, optionally, one or more adjacent layers, of substantially non-foamed thermoplastic; the central layer being substantially free of thermo-hardened materials; the central layer being substantially resistant to bagging and capable of substantially maintaining its shape.

2. The vehicle according to claim 1, further characterized in that the core layer has a decorative layer laminated to one of its main surfaces.

3. The vehicle according to claim 2, further characterized in that the decorative layer is selected from the group consisting of a felt layer and a fabric layer.

4. The vehicle according to claim 1, further characterized in that the central layer is substantially free of fiber mats of thermoplastic or thermoplastic materials.

5. The vehicle according to claim 1, further characterized in that the central layer consists essentially of an extruded thermoplastic foam; the roof liner additionally having a decorative layer laminated to a major surface of the central layer.

6. The vehicle according to claim 1, further characterized in that the central layer consists essentially of an extruded thermoplastic foam and one or more layers of a substantially unfoamed thermoplastic.

7. The vehicle according to claim 1, further characterized in that the foam has an approximate density of 16 to 160 kilograms per cubic meter, before manufacturing or thermoforming.

8. The vehicle according to claim 1, further characterized in that the foam has an approximate density of 16 to 80 kilograms per cubic meter, before manufacturing or thermoforming.

9. The vehicle according to claim 1, further characterized in that the thermoplastic comprises more than 50 weight percent of monomeric propylene units, on the total weight of the propylene polymer material.

10. The vehicle according to claim 1, further characterized in that the thermoplastic comprises about 70 weight percent or more of monomeric propylene units, based on the total weight of the propylene polymer material.

11. The vehicle according to claim 1, further characterized in that the foam is a polyester foam.

12. The vehicle according to claim 1, further characterized in that the foam is a polycarbonate.

13. The vehicle according to claim 1, further characterized in that the foam is a polyamide.

14. The vehicle according to claim 1, further characterized in that the foam has a cross-sectional thickness of 1.5 millimeters or more.

15. The vehicle according to claim 1, further characterized in that the foam has a cross-sectional thickness of 3 millimeters or more.

16. The vehicle according to claim 1, further characterized in that the foam is constituted by two or more laminated sheets.

17. The vehicle according to claim 9, further characterized in that the foam is an extruded foam, of coalesced strand configuration.

18. The vehicle according to claim 1, further characterized in that the foam has a charge in the form of particulate material and / or fibers.

19. The vehicle according to claim 1, further characterized in that the foam has a cross-sectional thickness of 1.5 millimeters or more; the thermoplastic comprises more than 50 weight percent monomeric propylene units, based on the total weight of the propylene polymer material; the foam having an approximate density of 16 to 160 kilograms per cubic meter, before manufacturing or thermoforming.

20. The vehicle according to claim 1, further characterized in that the foam has a cross-sectional thickness of 3 millimeters or more; the thermoplastic comprises about 70 weight percent or more of the monomeric propylene units, based on the total weight of the propylene polymer material; and the foam has an approximate density of 16 to 80 kilograms per cubic meter, before manufacturing or thermoforming.

21. The vehicle according to claim 1, further characterized in that the foam has one or more plates or profiles not foamed therein.

22. A process for assembling a roof lining and installing it in a vehicle, the vehicle having a passenger compartment and a roof located above the passenger compartment; characterized in said process because it comprises: a) providing a thermoformable core layer, comprising an extruded thermoplastic foam, and optionally one or more adjacent layers of a substantially unfoamed thermoplastic, wherein the core layer is substantially free of thermo-hardened materials, is substantially resistant to bagging and is able to substantially maintain its shape; b) thermoforming the central layer, applying heat and mechanical pressure to form a roof lining; c) place the roof lining adjacent to the underside of the roof.

23. - The process according to claim 22, further characterized in that the decorative layer is placed adjacent to, and parallel to, the central layer and laminated thereto; and the decorative layer is laminated to the core layer before or after the thermoforming of the core layer.

24. The process according to claim 22, further characterized in that the foam has a cross-sectional thickness of 1.5 mm or more; the thermoplastic comprises more than 50 weight percent monomeric propylene units, based on the total weight of the propylene polymer material; and the foam has an approximate density of 16 to 160 kilograms per cubic meter, before manufacturing or thermoforming.

25. The process according to claim 22, further characterized in that the foam has a cross-sectional thickness of 3 millimeters or more; the thermoplastic comprises about 70 weight percent or more of monomeric propylene units, based on the total weight of the propylene resin material; and the foam has an approximate density of 16 to 80 kilograms per cubic meter, before manufacturing or thermoforming.

26. The process according to claim 22, further characterized in that the foam has one or more plates or profiles not foamed therein.

27. The process according to claim 22, further characterized in that the foam is a polyester foam.

28. - The process according to claim 22, further characterized in that the foam is a polycarbonate foam.

29. The process according to claim 22, further characterized in that the foam is a polyamide foam.

30. The process according to claim 1, further characterized in that the foam has one or more plates or profiles not foamed therein. 31.- A vehicle roof liner having at least one thermoformed core layer having a thickness in the range of 1.5 mm to 25 mm; the core layer of an extruded thermoplastic foam having a gel content of less than 10 percent and, before thermoforming, an open cell content of less than 50 percent; a density on the scale of 16 to 200 kilograms per cubic meter, a width of at least 30.48 cm and an average cell size on the scale of 1.0 to 5.5 mm. 32.- The roof lining according to claim 30, further characterized in that the thermoplastic foam has a foam index of more than 2.0. / '- < - / To SUMMARY A vehicle that has an improved roof lining. The roof liner comprises a thermoformed central layer. The central layer 5 comprises a thermoplastic foam and, optionally, one or more adjacent layers of a substantially unfoamed thermoplastic. The core layer is substantially free of thermosetting materials and preferably free of mats or glass or glass fiber batt. A decorative layer, such as a layer of 10 felt or a layer of fabric, preferably laminated to the central layer. The roof liner is substantially resistant to bagging and is capable of substantially maintaining its thermoformed shape when installed in the vehicle. It also calls for a process to assemble or form a roof liner and install it in 15 a vehicle. twenty