[1]'Uiiited States Patent Office5 112 3,534,129 SEAT CONSTRUCTION AND THE LIKE. Gunter Friedrich Bartel, Tecklenburg, Germany, assignor to Elastomer A.G., Chur, Switzerland, a corporation of SwitzerIand Filed Mar. 21, 1968, Ser. No. 714,964 Claims priority, application Germany, Apr. 6, 1967, 1,685,172 Int. Cl. B29d 9100 U.S. Cl. 264-45 4 Claims ABSTRACT OF THE DISCLOSURE A seat such as a chair, sofa or the like having a rigidpolyurethane foam frame and a semi-rigid polyurethane foam upholstery layer cohesively bound together is molded in separate molding steps without removal from the mold between molding steps. This invention relates generally to an article of furniture and more particularly to a seat of novel construction and a method and apparatus for making it. A chair or similar seat is usually constructed by assembling separately constructed frame, springs and cushions. The frame is often made from wood and has coil springs or sprin.- elements supported between the chair bottom and cushion upon which the occupant sits. Legs, rollers or the like are built into the frame or attached to it before or after upholstering chairs. Anupholstered vehicle seat is installed on a track or in a fixed position in the vehicle. It has been proposed to use plastics in seat construetion and polyurethane foams have been accepted commercially particularly for making seat cushions. It has also been proposed to mold the supporting portion and the cushioning portion of a chair separately and to later adhesively bind them together. One such method is disclosed in U.S. Pat. 3,314,721. Methods of this type have the disadvantage of requiring handling of the elements of the chair and the resulting product may separate into its component parts if the adhesive deteriorates upon aging. -It is an object of this invention to provide an improved method of molding a plastic seat. Another object of the invention is to provide a method for making a unitary upholstered seat frame having molded elements cohesively bound together. Still another object of the invention is to provide an improved seat construction having component parts of differing degrees of rigidity molded into cohesively bound relationship. Other objects wiH become apparent from the following description with reference to the accompanying drawing in which: FIG. 1 is a perspective view, partially in section, of one embodiment of this invention; FIG. 2 is a perspective view, partially in section, of an other embodiment of the invention which is adapted for installation in a vehicle; FIG. 3 illustrates diagrammatically an embodiment of an injection mold suitable for molding a seat in accordance with this 'mvention; and FIG; 4 illustrates in a fragmentary section a portion of the embodiment of FIG. I taken along the line IV-IV. The foregoing objects and others are accomplished in accordance with this invention, generally speaking, by providing a seat having a frame or support of molded rigid polyurethane foam and an upholstery layer of a semi-rigid polyurethane foam cohesively bound together. Such a seat is made in accordance with this invention by molding the frame from a foamable polyurethane reaction mixture which expands into a rigid polyurethane and then molding an upholstering element over the frame before removing it from the mold from a foamable reacPatented Oct. 13, 1970 2 tion mixture which expands and solidifies into a semi-rigid polyurethane foam. The resulting molded constructi6n may then be covered with a cushion of flexible polyurethane foam. The process provided by this invention is not only simpler than those heretofore available but is also less expensive. Mold costs are greatly reduced because the same mold bottom can be used interchangeably with several lids or tops of different configurations to produce seats 10 having a variety of shapes all having the same basic frame structtire. Also, as described in more detail hereinafter, danger of damaging the frame during construction of the seat is avoided by leaving the frame in the protective mold until after the frame has been upholstered. 15 In one embodiment of the invention, the frame of rigid polyurethane foam, the upholstery of semi-rigid polyurethane foam and a cushion layer of fiexible polyurethan foam are molded successively without removal from the mold, using the same mold bottom but changing 20 the mold top and the composition of the foamable reaction mixture. This process can be practiced to advantage using an apparatus of the type described in my copending application Ser. No. 710,903, filed Mar. 6, 1968, based on German application No. E 33,545, filed Mar. 8, 1967. 25 With such an apparatus the same reactive components can be used in making all of the polyurethane foams with the rigidity or flexibility thereof being determined by the ratio of components used. The necessary fastening means for installation of legs 30 or for securing the seat to a vehicle fioor can be placed in the mold and the frame molded thereabout, if desired. Rigid polyurethane foams, semi-rigid polyurethane foams and flexible polyurethane foams and formulations and technics for making them are widely known. For 35 example, both methods and compositions for making foams suitable for use in this invention are disclosed in "Hi.-h Polymers," vol. XVL entitled "Polyurethanes: Chemistry and Technology," Part @II, by J. H. Saunders and K. C. Frisch, published by Interscience Publishers 40 in 1964. Flexible foams particularly advantageous for use in this invention are described in copending U.S. patent application Ser. No. 677,013. It is preferred to use poly (alkylene ether) polyurethanes prepared from known two component systems which are mixed together at the time 45 of molding. A rigid polyurethane foam best suited for use as a frame in accordance with this invention has a density of at least about 40 kg./M.3a compressive strength of about 2.5 kp./eM.2 at 8% compression and a flexure strength 50 of a out 4 . cm. at 17 mm. bending. The rigid foam may be made self-extinguishing, if desired. A -flexible foam well adapted for use herein has a compression set of less than about 5% after 72 hours at room temperature. Its deflection at 40% deformation must not 55 be greater than about 20p./CM.2 Its elongation should be not less than about 100%. A semi-rigid foam has properties between those of the rigid foam and flexible foam and at 40% deformation should have a deflection of about 50 p./CM.2. The exact degree of rigidity and flexibility 60 will vary within conventional limits from one seat construction to another depending upon where it will be used. The method provided by this invention is particularly advantageous for molding polycaprolactone polyester 65 polyurethanes because reaction mixtures which produce such polyurethanes can be reacted at room temperature or over a wide temperature range Because of the noncritical reaction temperature, mold design can be imple with(>ut means for heating the mold. The apparatus and 70 compositions disclosed in my aforesaid application can be used to mix and meter the foamable reaction mixture into the mold.
[2]3 As indicated hereinbefor--, the mold used to manufacture the seat is so designed that the mold bottom and one top cooperate to shape the frame. The same bottom containing the molded frame then combines with a second mold top to shape the upholstery. If a cushion is molded on top of the upholstery, a third top is combined with the bottom and molded in place while the frame and upholstery unit is still in the mold. One of the important advanta.-cs of this invention is realized by usin.- a foamable reaction mixture containing as the polyol a polycaprolactone polyester. Conipositions and a process suitable for making foams suitable for this invention are disclosed in U.S. Pat. 3,240,730. Systems comprisin.- a quasi-prepolymer mixture of poly (alkylene ether) polyol and an organic polyisocyanate and a sccond component which is a mixlure of a polyfunctional polyether polyol, water and catalyst can also be used to advanta.-e but the polyctprolactone polyester based systems are preferred. With the latter system an exceptionally wide ran.-e of ri.-idity can be obtained bY -variation in formulation permittin.- the use of several mixing devices to char.-e different compositions into the mold as described in more detail in my aforesaid application Ser. No. 710,903. All of these mixing devices can draw from the same storage tank but use different ratios thereof to obtain different de.-rees of ri-idity in the resultin@ foam. It then becomes possible, for example, to supply the material for the upholstery and the cushion or finish upholstery in successive steps tbrotigh the same mix head. In this case the time required for switching the meterin- bead and for changing the mold top is just sufficient for the mixture introduced in the :Prst step to foam out completely, particularly when materials reacting at room temperature are used. The process of the invention is advanta-eous for making a large number of the same kind of seats at low cost. It is therefore particularly advantageous for makin- s,-ats for automobiles, aircraft and the like where special designs are required btit large numbers of seats of the same design are used. A method for making a vehicle seat having a concave n-ietal insert formin@ the base of the seat frame is described hereinafter. The fabrication of a molded frame above a concave surface is ordinarily very difficult and expensive because it does not have any ridges or corners to facilitate adherence of the foam thereto. However, it can be accomplished in a simple rnanner in accordance with this invention on a mass production scale. It is to be noted that because one foam layer is molded directly over the other, the frame, upholstery and molded cushion are cohesively bound to,-ether forming a stron.unitary construction not dependin.- upon an adhesive composition. Referring now to the drawings, FIGS. I and 4 illustrate one embodiment of a chair having a supportin.- member or frame 10 of rigid polyurethane foam shaped into a bottom or seat portion, a back and arm portions, and a semi-rigid polyurethane foam upholstery layer 20; the opposin.- surfaces of 10 and 20 being securely bound together because 20 was foamed in place over the surface of 10 as will be explained in more detail hereidafter. As illustrated in FIGS. 1 and 4, the thickness of frame 10 and upholstery 20 varies depending upon the particular part it is to form of the completed chair. The softness or rigidity of the various parts of the chair can be varied to the anatomical requirements of an occupant of the chair by a variation in thickness of the upholstery 20. The chair of FIGS. I and 4 is the type which has loose or removable cushions 30 and 31 of flexible polytirethane foam covered with a textile leather or vinyl covering of the type conventionally used in upholsteredfurniture. Chair legs, castors or the like can be attached in appropriate locations on the underside of frame 10 by conventional methods to the completed chair. FIG. 3 illustrates schematically the chair of FIG. 1 31534@129 4 positioned in a mold in which it has been fabricated. In molding frame 10, mold top 12 is swun- to the ri-ht as positioned in the drawing, pivoting on hinge 14 attached to mold bottom 16 until the mold is closed forming internally the outline of frame 10. A metered amount of liquid polyurethane foaming mixture is injected into the mold where it expands and solidifies into a rigid polyurethane foam frame 10. Mold top 12 is then swung out of the way and the second mold top 22 mounted 10 on mold bottom 16 by means of hinge 24 is swung into place with frame 10 still positioned in the mold. Closing of the mold with top 22 leaves a cavity above frame 10 in the mold havin.- the configuration of upholstery 20. This cavity is filled by metering in a predetermined vol15 ume of liquid foamable polyurethane composition which expands to fill the void and solidifies into a semi-rigid polyurethane upholstery layer 20 with the opposing surfaces of frame 10 and upholstery 20 bein,a cohesively bound to,-ether. For simplicity, mold tops 12 and 22 are 20 shown in section, it bein.- understood that side parts are provided havin.- the contour of the arm portions shown in FIGS. I and 4. Frame 10 can be used to support upholstery layers 20 of various configurations by replacing mold top 22 with a top of other desired configurations. )5 Mold bottom 16 can be attached to more than two mold tops when a seat or chair is to be provided with more than two molded layers or elements. FIG. 2 illustrates a seat molded in one mold bottom Nvith three mold tops, the seat having frame 10 of rigid 30 polyurethane foam, upholstery 20 which is molded semiri.-id polyut-ethane foam and a molded flexible polyurethane foam cushion 40. The seat was molded in accordance with the process described above with reference to FIG. 3 but the mold had three tops and three separate foamable polyurethane compositions were injected successively into mold cavities formed by the tops. The seat of FIG. 2 is provided with concave cap 50 of amal-netizable material such as, for example, soft iron, nickel or other metal. Cap 50 was placed in the mold 40 before the foamin.- mix which formed frame 10 and upon charging the polyutethane foamin.- mix for frame 10 in the mold, the foamable liquid reaction mixture expanded and solidified in the mold cavity with cap 50 coverinpart of that side which was to be the external support side of 45 frame 10. In the embodiment of FIG. 2, cap 50 has an external convex surface which pivots in concave shaped recess 52 of carria.-c 60. Ball bearings 64 reduce friction between 52 and 50. Electric or permanent magnets 62 embedded in carria.-c 52 hold the seat in position with 50 respect to carria,@e 52. Rollers 66 assist in horizontal movement permitting adjustment, an arran,@ement particularly advanta.-eous for a vehicle seat. The arrestin,-, ma,@ncts 62, if electromagnets, can be turned on and off when reclinin.- the seat. If ma.-nets 62 are permanent 55 ma,@nets, they can be mechanically ictuated in some circumstances with the use of ma-net short circuit devices. This invention also makes is p'ossible to make seats provided with air pockets or voids which can be inflated. To accomplish this, a film or films of a plastic material such 60 as, for example, polyvinyl chloride film is inserted between the layers of the polyurethane foams over preselected areas to prevent the foam of one layer from being cohesively bound to the adjacent one in the area covered by the film. The two adjacent layers of poly65 urethane foam cohere to each other atound the ed@es of the film, however, to form a pocket or void. Although the invention has been described in consider. able detail for the purpose of illustration, it is to be 7o understood that such detail is solely for this purpose and that variations can be made by those skilled in the art withotit departing from the spirit o.r scope of the invention. I
