METHOD OF PRODUCING AN INFLATABLE ELEMENT AND AN INFLATABLE ELEMENT

Abstract: The invention concerns a method of manufacturing an inflatable element (1) which is intended to be used as a support structure or a part thereof of a piece of furniture for sitting and lying purposes or a part of a piece of furniture, wherein the element (1) is manufactured by heat seam welding (11) of a sheet or sheets of a thin plastic material for forming a closable container, and whereby the element is provided with a closable opening. The element is produced from a soft and flexible material which is comprised of a copolymer of polyolefins and the closable opening is included in a separately produced opening element (10) which is heat seam welded (11') to a portion of the wall of the intended thin wall element. The invention also concerns an element produced in such a method and the piece of furniture including such elements.

Description: METHOD OF PRODUCING AN INFLATABLE ELEMENT AND AN INFLATABLE ELEMENT This invention concerns a method of manufacturing an inflatable element according to the preamble of claim 1 and an inflatable element according to the preamble of claim 10. Upholstery including beds comprise about 40% of the total furniture production for the home market . While the remaining furniture production has undergone radical change into highly industrialized production during the last three decades, manufacture of upholstery is still directed to handicraft. Traditional manufacture of upholstery and beds is in rough terms a process for fixing together a number of different materials to each other. This principle makes separation of the product after use, one of the fundamentals in recycling, into different categories of material, expensive and difficult. It is also clear that it is difficult for the manufacturer to find materials with acceptable technical performance at reasonable prices. Because of the complexity of conventional upholstery it is believed that recycling thereof will necessitate the starting of new specialised plants for recycling. This will increase costs for upholstery further. A further problem with upholstery is the substantial weight and volume of the products which makes storage and transport costly and energy consuming. In a near future, because of the responsibility of the manufac¬ turer, conventional upholstery will be subject to demands for recycling of material and energy, which brings about further costs for the products. Furniture items with pneumatic support structures are well known. Such furniture items are advantageous, since they are transportable in a compressed state which facilitates export as well as distribution via mail order. Further features are low weight and low price. SE-B-368 502 describes a body support device with so called spare elements which are intended to be inflated with air or the like before their insertion into a shape defining cover. The elements are intended to be manufactured through seam welding of polyvinyl chloride. SE-B-426 545 describes a piece of furniture with a cover which is filled with balloon like bodies. An important problem with previously known pneumatic furniture items is lack of comfort, since the materials which are used up to now, in an inflated state, give the elements an undesired rigidity. The often used heat seam welding technique in connec¬ tion with the previously used materials make the furniture items unreliable as to leakage. The method of providing the elements with an opening involves glueing or clamping opera¬ tions which gives sealing problems. Further the used materials are directly environmental hostile or at least dubious with respect to the environment. The above problem is solved by using the method according to claim 1 and the inflatable element according to claim 10. It has surprisingly been found that heat seam welding of sheets of a soft and flexible material, which is comprised of a copolymer of polyolefines because of the softness assures the comfort of the resulting piece of furniture and result in very good sealing properties in a conventional heat seam welding process. Heat seam welding of a separate opening portion, ensures the sealing properties also in this area and makes it possible to optimize the properties of the opening portion, with respect to material as well as sealing properties. The used materials are readily recyclable in recycling plants which are already in use in many countries. This is accentuated when using a copolymer with ethylene which gives a low price for the material and the manufacture. By the copolymer including EMA, EBA, EVA, EEA, EAA or the like the resulting element is given very good properties with respect to producibility and softness, and these properties are enhanced when EMA is present at 17-40% or more preferred at 20- 30% or most preferred at 24-26% with polyethylene or most preferred LDPE as the main constituent. Adding peroxide to the starting material is advantageous because on the one hand manufacture technical effects and on the other hand, which is very important for a piece of furni¬ ture, essential reduction of "the smell of plastic". By adding a slip agent to the material a great number of advantages are achieved related to the elements being given a comfortable low friction surface and noise production within the material itself and between adjacent element being essen¬ tially reduced. It has also been found that adding a slip agent essentially simplifies introduction of inflated elements into a cover, since the slip agent reduces the friction between adjacent elements and between the elements and the cover. This considerably simplifies and reduces time of the introduction. Slip agents that have been found effective are, as examples, erucamide and oleamide. Slip agent is preferably added at from about 1% for so called low slip to slightly above about 3.2% for so called high slip. A very advantageous aspect of the invention is achieved by the feature according to claim 17. Hereby it is possible to radi¬ cally reduce the inflation time, which otherwise may be very considerable if traditional inflation is used, of an easy clair, a bed or a sofa. As an example it may be mentioned that the total air volume of a sofa is typically around 600-1000 1 which when using a conventional inflation technique for the homes result in an almost insurmountable inflation time. Further, because of the indicated dimension, if the elements are undivided inside, it is possible to place sealing means such as repair patches or clots of contact glue or the like from the inside at a damaged area so as to repair a hole in the wall element. By allowing repair to be conducted from the inside the forces from the contained medium will enhance and not diminish the adhesion and the repair place will be pro¬ tected from outside influences. A further essential aspect of the dimension of the opening is the possibility when manufacturing to quickly empty the finished element from air for further packeting. By "hair dryer" is intended hand held devices, normally with pistol grip, with or without the provision for switching of the heating element. Such devices are common in the homes and normally have an output nozzle diameter between about 40 and 60 mm. An inner diameter of the opening between about 30 and 55 mm therefore allows the element to be conveniently inflated directly using the hair dryer. Using an intermediate element, preferably simply having the shape of an elongated funnel, between a hair dryer and the opening allows inflation of the element when the inner dimension of the opening diverge to much. It should be observed that a circular opening is pre¬ ferred but that other shapes, e.g. somewhat angular, are not excluded. By the opening portion being manufactured in an injection moulding process, the possibility to choose the design of the opening suitable to the particular application is achieved. This method result in high quality, economic elements. The invention also concerns a piece of furniture including a support structure including element according to the above. When the furniture item includes a cover enclosing the support structure, it is advantageous that the cover is adapted in such a way that the elements only have to be inflated to between about 75 - 90%, which considerable enhances the comfort of the piece of furniture in comparison to previously known furniture items having pneumatic support structures, where it has been the question of inflating the support elements to a maximum. The invention will now be described in greater detail with reference to an embodiment and at the background of the annexed drawings, wherein: Fig. 1 shows a support structure consisting of elements accor¬ ding to the invention for a piece of furniture, Fig. 2 shows an element according to the invention in a per¬ spective view, Fig. 3 shows, partly in a section, the element according to Fig. 2 in a side view, Fig. 4 shows an element according to the invention in an empty state, Fig. 5 shows a different design of an element according to the invention, Fig. 6 shows the opening area of an element according to the invention, Fig. 6a shows the detail in Fig. 6 in a separated state and in a larger scale, Fig. 7 shows the opening area of an other element according to the invention in a sectional view, Fig. 8a-f show a support structure of a sofa and the process of placing said support structure in a shape determining cover, Fig. 9 shows a different embodiment of the element according to the invention, Fig. 10 shows a detail of the element of Fig. 9 in a larger scale, Fig. 11 shows another embodiment of the opening area in an element according to the invention, Fig. 12 shows a further embodiment of an element, and Fig. 13 and 13A show diagrammatically a support structure for a variety of applications. The support structure shown in Fig. 1 is intended for sofa, a bed or the like and consist of four inflatable elements 1 which are manufactured by heat seam welding of two sheet portions, each in the finished element mainly having a U-shaped section, said sections being intended to be looked upon at an angle of 90° with respect to each other. This is more clearly shown in Fig. 2 where the upper sheet portion has an extension along the arrow A-A and the lower sheet portion has the extension along the arrow B-B. Meeting edges of the sheet portions are heat sealed welded in a conventional manner with regard to parame¬ ters as clamping pressure and temperature. It is possible to conduct welding using different known methods as contact heat, ultrasonic heat etc. The element shown in Fig. 1 and 2 thus includes a continuous seam 11. Preferably centrally on one side, the element is provided with an opening portion 10 which will be described in detail below. Fig. 3 shows the element according to Fig. 2, partly in sec¬ tion, showing the opening portion 10 which is depressed in such a way that an applied lid 3 is inside or generally in level with the surrounding wall portion of the element. Fig. 4 shows the element 1 in a collapsed state with radically reduced volume which is the case in distribution etc of a piece of furniture based on this invention. Fig. 5 shows a different embodiment of the inflatable element whereby the upper side 12 and the lower side 12 ' as much as possible have been made free from seams. The seams are present only at the parallel side edges and in central portions of the sideward directed sides. Hereby the stiffening influence from the seams to the comfort of a resulting piece of furniture may be reduced. Fig. 6 and 6a show the opening portion 10 of the elements with the indicated seam 11'. The lid 3 may be fixed in the opening in the opening portion 10 by for example screw thread, or as is shown in Fig. 7, by depressing lid 3' which comprises a some¬ what larger diameter than the opening of the opening portion 10. In this case the opening is defined by a tube shaped neck portion 13 which is an excellent tightening seat for the lid 3'. Preferably the tube shaped neck portion is slightly conical inwardly while the lid 3' is provided with the corresponding design. Fig. 8a and 8b show in detail the support structure of a sofa according to the invention with seat elements 1', arm support elements 2' and back support elements 5'. Fig. 8c-8f show the process of finishing a seating furniture item according to the invention whereby 14 ' indicates a finished complete shape determining cover and 20 an optional insertion sheet of polyethylene, batting or the like as a levelling layer. The seat elements 1' are inserted according to Fig. 8b in their inflated state from below into the cover which is thereafter closed. Further, the arm support elements 2' are inserted in their respective pockets and finally the back support elements 5' are inserted as is illustrated in Fig. 8f. It should be noted that insertion is much simplified if the elements are manufactured from a material including a slip agent, since otherwise the insertion of the elements may be considered troublesome. Fig. 9 shows a further embodiment of the invention, from which and also from Fig. 10 it is shown that the opening 21 in this case is located in a seam area of the element 1. The portion surrounding the opening 21 is of course possible to seam weld to the sheet material of the wall 20 of the element. As is shown in Fig. 9, in this case the element is closed with a lid device 22, 23 which consists of first lid 22 having an outer diameter corresponding to a hole 21 allowing inflation with a hair dryer, and an inner diameter of a centrally located inner through hole which is designed for final inflation with the aid of particular pump, with the mouth or the like. This inner hole is thereafter sealed with the inner lid 23. Both lid 22 and 23 are provided with sealing flanges which engage the surrounding material. This lid construction is particularly useful when the elements are to be given a higher pressure than what is nor¬ mally intended, e.g. in certain particularly high loaded elements. Fig. 11 shows a different embodiment of the opening portion 10'' having the tube shaped neck portion 13 adapted for co¬ operation with a particularly shaped lid 3'', which in its lower portion is provided with a locking flange 24 for the cooperation with the inward surface of the neck portion 13. The sealing between the lid and the neck portion is achieved in the above mentioned manner, but it is also possible to provide the lid 3 ' ' with outward sharp surrounding tightening flanges on the part having reduced diameter. Said flange or flanges exerting tightening cooperation with the inner envelope surface of the neck tube 13. Fig. 12 shows a variant of the element according to the inven¬ tion whereby a sheet is used which is directly manufactured in tube shape, normally as an "endless" tube. Hereby only two end walls are welded 11 against a sheet tube portion for forming the element 1. By placing the welded seams 11 such, as is e.g. shown on Fig. 2 and 12, the great advantage is achieved that crossing seams are avoided. Places having crossing weld seams (T-crosses as well as X-crosses) are particularly sensitive places as to leakage. Fig. 13 and 13A show diagrammatically an alternative support structure built from three elements 1 according to the inven¬ tion which may be linked together in meeting welding seams lla or separate, and in that case they are manufactured according to the above principles. The elements are in this case con¬ structed more plate-like and may therefore be used "folded together" as an easy chair or levelled as a mattress. The invention is not limited to the container like elements which are shown in the Figures but all kinds of inflatable elements within the definition of the claims are within the scope of the invention, e.g. also air mattress type elements which are intended to be used in a levelled as well as e.g. in differently folded position, in principle as has been described in connection with Fig. 13 and 13A above. Also irregularly shaped elements are possible and are intended with the inven¬ tion.

Claims: C L I M S: 1. Method of manufacturing an inflatable element (1) which is intended to be used as a support structure or a part thereof of a piece of furniture for sitting and lying purposes or a part of a piece of furniture, wherein the element (1) is manufac¬ tured by heat seam welding (11) of a sheet or sheets of a thin plastic material for forming a closable container, and whereby the element is provided with a closable opening, c h a r a c t e r i z e d in that the element is produced from a soft and flexible material which is comprised of a copolymer of poly- olefines and that the closable opening is included in a sepa¬ rately produced opening element (10) which is heat seam welded (11') to a portion of the wall of the intended thin wall element. 2. Method according to claim 1, c h a r a c t e r i z e d in that the element is produced from a copolymer of ethylene. 3. Method according to claim 2, c h a r a c t e r i z e d in that the thin wall element is produced from a copolymer includ¬ ing EMA (ethyl methyl acrylate), EBA (ethyl butyl acrylate), EVA (ethylene vinyl acetate) or EEA or EAA or the like. 4. Method according to claim 3, c h a r a c t e r i z e d in that the thin wall element is produced from a material inclu¬ ding EMA at an amount of 17 - 40% or more preferred at 20 - 30% or most preferred at 24 - 26% with polyethylene or most pre¬ ferred LDPE as the main constituent. 5. Method according to any of the claims 1 - 4, c h a r a c t e r i z e d in that peroxide is added to the material so as to increase melt flow rate and/or to diminish odour. 6. Method according to claim 5, c h a r a c t e r i z e d in that peroxide is added at an amount of about 1000-1100 PPM. 7. Method according to any of the claims 1 - 6, c h a r a c t e r i z e d in that a slip agent is added to the material. 8. Method according to any of the claims 1 - 7, c h a r a c t e r i z e d in that the opening portion is produced in an injection moulding process which proceeds the heat seam welding. 9. Method according to any of the claims 1 - 8, c h a r a c t e r i z e d in that the seams (11) are located such that crosses between weld seams are avoided (Fig. 2, 12) . 10. Inflatable element (1), which is intended to be used as a support structure or a part thereof of a piece of furniture for sitting and lying purposes or a part of a piece of furniture, wherein the element is produced by heat seam welding (11) of a sheet or sheets of a thin wall plastic material for the produc¬ tion of a closable container, and wherein the element is provided with a closable opening, c h a r a c t e r i z e d in that the element (1) is produced from a soft and flexible material which is comprised of copolymer of polyolefines and that the closable opening is included in a separately manufac¬ tured opening portion (10), which is heat seam welded (11') to a portion of the wall of the thin wall element. 11. Element according to claim 10, c h a r a c t e r i z e d in that it is produced from a copolymer of ethylene. 12. Element according to claim 10 or 11, c h a r a c t e r i z e d in that it is produced from a copolymer including EMA (ethyl methyl acrylate), EBA (ethyl butyl acrylate), EVA (ethylene vinyl acetate) or EEA or EAA or the like. 13. Element according to claim 12, c h a r a c t e r i z e d in that it is produced from a material including EMA at an amount of 17 - 40% or more preferred at 20 - 30% or most preferred at 24 - 26% with polyethylene or most preferred LDPE as the main constituent. 14. Element according to any of the claims 10 - 13, c h a r a c t e r i z e d in that peroxide is added to the material so as to increase melt flow rate and/or to diminish odour. 15. Element according to claim 14, c h a r a c t e r i z e d in that peroxide is added at an amount of about 1000-1100 PPM. 16. Element according to any of the claims 10 - 15, c h a r a c t e r i z e d in that a slip agent is added to the material. 17. Element according to any of the claims 10 - 16, c h a r a c t e r i z e d in that the inner dimension of the opening is between about 30 and 55 mm so that it is adapted for indirect or direct cooperation with the blower function of an ordinary hair dryer. 18. Element according to any of the claims 10 - 17, c h a r a c t e r i z e d in that the opening portion is produced in an injection moulding process which proceeds the heat seam welding. 19. Element according to any of the claims 10 - 18, c h a r a c t e r i z e d in that the opening is defined by a tube shaped portion which is intended to cooperate with a lid penetrating the neck portion. 20. Element according to any of the claims 10 - 19, c h a r a c t e r i z e d in that the opening portion is shaped in such a way that an applied lid is located inside or in substantially in level with the surrounding wall portion of the thin wall element. 21. Piece of furniture including a support structure which includes at least one element (1) according to any of the claims 10 - 20. 22. Piece of furniture according to claim 21, c h a r a c t e r i z e d in that it includes a cover (14') surrounding the support structure and that the elements are adapted to be inflated to only between about 75 - 90%.

Inventors: DRANGER JAN, DRANGER, JAN
Applicants: DRANGER JAN, DRANGER, JAN
Application year: 1996
Main classification: A47C27
IPC codes: A47C27