FOAMED MOULDED ARTICLES SUCH AS DOORS OR PARTITIONS

Abstract: Moulded article, based on two optionally profiled sheets (1) made of "open" foamed plastic and connected to each other by an internal edge reinforcement (3) between them, the hollow space between said two sheets, if present, is filled up with a foamed material (2) having a lower density than that of the "open" foamed sheets.

Description: Foamed moulded articles such as doors or partitions The invention relates to moulded articles such as doors - in particular inside doors, outside doors and cupboard doors - and partitions, which may or may not be profiled, and which are made of foamed plastic material, in particular foamed polyurethane. Polyurethane doors which are made up of two profiled sheets with an internal wooden edge reinforcement are known. These profiled sheets are produced using a top and bottom mould, under a moulding pressure of, for example, 2 kg per sq.ctα. In view of this relatively high moulding pressure, very expensive epoxy resin moulds have tp be used here. The profiled polyurethane sheets produced in this way, which have a density of about 350 kg per cubic metre, are then fixed back to back and, after milling out of the space left there, are provided with the internal wooden edge reinforcement. However, on account of the high density of about 350 kg per cubic metre of the polyurethane foam, a relatively large quantity of material is used, which adversely affects the cost of the doors in question. Since, for example, the thickness is 40 mm for normal inside doors, profiled sheets of such a thickness are used that two sheets together have a thickness of 40 mm. On account of this considerable thickness, such doors have, however, the disadvantage that they are very prone to becoming warped. It has been found that the above-mentioned disadvantages can be eliminated from moulded articles such as polyurethane doors known from the state of the art, using new moulded articles which are characterised in that such moulded articles are made up of two flat sheets, one flat sheet and a sheet which is profiled at least on one side, or two sheets profiled on at least one side, said sheets being made of open foamed plastic with an internal edge reinforcement between them, while the hollow space between the two sheets, if there is one, is provided with a foamed material. The invention more particularly relates to moulded articles which are made up of two flat sheets or two sheets which are profiled on one side, made of foamed polyurethane with an internal edge reinforcement between them, while the hollow space between the two sheets, which may or may not be profiled, is filled up with a foamed material which has a lower density than the material of the.sheets. The foamed material in the hollow space is preferably a polyurethane foam which has a much lower density than that of which the possibly profiled sheets are constructed, for example 20 - 80 kg per cu. metre, as opposed to 150 - 900 kg per cu. metre. The wooden edge reinforcement can also be replaced by another sturdy material at a later stage, if desired. The moulded articles according to the invention can be produced by: - spouting up the plastic material for foaming, preferably polyurethane t o a mould; - allowing the polyurethane mass to set without exerting external pressure, following which the sheet, which may or may not be profiled, can be separated from the mould; - reducing to size the edge thickness of the sheet for the internal edge reinforcement by means of, for example, milling or grinding; this measure becomes superfluous at automation. - fitting the steely,plastic or preferably wooden edge reinforcemen andintroducing the material to be foamed into the hollow space between the two sheets, which may or may not be profiled, for example polyurethane, said foam having a much lower density than the sheets, and - allowing the material for foaming to set in the hollow space between the two sheets, while during setting thereof the moulded article is held in shape by external means, such as a press. The latter provision is necessary, since otherwise during the setting of the material for foaming in the hollow space between the sheets, these sheets might bulge out. The pressure required for exerting on the the moulded article is, however, slight in this case. The moulded articles according to the invention are "solid" objects, which on that account have excellent properties in use. On account of their special construction, the moulded articles have little or no tendency to warp, they possess excellent insulating properties, they are easy to handle as far as weight is concerned, and they can be provided with any desired profiling depending on the mould, which is cheap to buy. The moulded articles according to the invention can be in the form of doors - in particular inside doors, outside doors, cupboard doors and kitchen doors - and partitions and the like, which on account of the profiling produced in them can give a particularly attractive effect. The advantages of the moulded articles according to the invention over those which are known from the state of the art will be explained below in further detail: a) For the production of the possibly profiled sheets according to the invention, one needs only to spoutupthe polyurethane for foaming - which is the material preferably used - on a mould, without the need for a top mould, which is normally used under elevated pressure. One of the consequences of this so-called "open" foaming is that moulds of relatively cheap material can be used for the production of the possibly profiled sheets according to the invention. b) By filling up the hollow space - if there is one - between the possibly profiled sheets of the moulded article according to the invention with a foamed material which has a much lower density than the material from which the sheets are made, one obtains "solid" moulded articles which are particularly advantageous both as regards properties -in use and as regards quantity of material used. On account of this use of foamed material with a much lower density in the above-mentioned hollow space, the cost per moulded article is also " considerably lower than a moulded article produced according to the state of the art. Moreover, the low- density foam completely fills up the hollow space between the profiled sheets, so that any deviations on the back of the profiled sheets according to the invention give no problem at all during production of the moulded articles according to the invention. c) The moulded articles according to the invention, such as, for example inside doors, outside doors, kitchen and cupboard doors, have the advantage over those according to the state of the art that they do not warp. As we said above, the warping in the known moulded articles is apparently due to the fairly great thickness of the- profiled sheets according to the state of the art, sometimes 20 mm, while this thickness in these possibly profiled sheets is maximum only 5 mm, for example 2 - 5 mm. The plastic material for foaming to be used for the profiled sheets according to the invention is advantageously polyurethane, which after setting has a density of 150 - 900 kg per cu. metre, depending on the standards to be set. However, other hard foam materials such as polystyrene, acrylonitrile butadiene styrene terpolymer, polyethylene and polypropylene foam materials can also be used. The material for foaming, which is introduced into the hollow space between the two sheets according to the invention, is preferably polyurethane. Such polyurethane after ' setting has a density of 20 - 80 kg per cu. metre. Other light materials which are cheap to foam, such as polystyrene, polyethylene, polypropylene and urea formaldehyde, can also be used. According to the invention, polyurethane is advantageously used for both the possibly profiled sheets and the material which is introduced into the hollow space between these sheets, with the proviso that polyurethanes of different densities are used. The use of polyurethane as a raw material for the moulded articles according to the invention has a number of advantages, vi.z; 1) a wooden structure is relatively simple to fix on polyurethane; 2) the quantity of polyurethane used is relatively low; 3) polyurethane has good insulating properties; 4) polyurethane is very easy to change in density or diversity; and 5) polyurethane is relatively simple to process and handle. The invention also relates to the individual sheets, profiled or otherwise, which can be used in the above-described moulded articles. Such sheets preferably consist of polyurethane foam with a density of 150 - 00 kg per cu. metre and have an average thickness of max. 5 mm, for example 2 - 5 mm. The invention is illustrated in greater detail with reference to the attached Figs. 1 and 2. Fig. 1 is an illustration of a door according to the invention, and Fig. 2 is a partial cross section along the line A:A in Fig. 1. The invention is particularly illustrated in Fig. 2, in which (1) represents a profiled sheet according to the invention, (2) represents the foamed material with a density which is much lower than that of the profiled sheet, and (3) represents a cross section of the internal edge reinforcement. It can be seen clearly from this figure that the hollow space present between the profiled sheets according to the invention is filled up with the light foamed material to which the moulded articles according to the invention owe their strength. More particularly, the moulded articles according to the invention can be designed, produced and subjected to a finishing process according to the method below. This method comprises the following stages: a) designing a model for, e.g., a profiled door; or silicones b) producing a mould on the basis of epoxy resin/reinforced with glassfibre, said mould being based on the model mentioned in (a); c) lubricating the mould; this measuαE is _a_TF_τIυcu.3 with silicones; d) heating the mould to a temperature of approximately 35 C; e) providing the mould, with a silicone-free mould release agent such as Acmosil 180; no release agent is necessary where a mould on the basis of silicones is used ; f) providing the mould with a barrier coat; this is also the base coat or shop primer; • g).spouting up the foamable polyurethane in layers. (density:+ 350 kg per cu. metre), following which the polyurethane is open foamed at a temperature of about 65 degrees C; h) removing the set, profiled polyurethane sheet from the mould, by means of, for example, compressed air; i) adjusting the edges of the set, profiled polyurethane sheet to the edge reinforcement to be applied, by means of milling; j) gluing the two profiled sheets onto a wooden frame; k) cutting to size of the door produced; 1) introducing the inner filling between the two profiled sheets by injecting with polyurethane (density: 60 - 1.5 kg per cu. metre), at a temperature of about 65 degrees C, where to prevent the sheets from bulging some external pressure is exerted on them; ) staining the profiled sheets in such a way that the grain of the wood becomes clearly visible; and n) applying a finishing coat of clear lacquer to the door. Flat doors or doors provided with one profiled side can also be produced by the above method.

Claims: - C L A I M S 1. Moulded article, characterised by two flat sheets, one flat sheet and a sheet which is profiled at least on one side, or two sheets profiled on at least one side, said sheets being made of open foamed plastic with an internal edge reinforcement between them, while the hollow space between the two sheets, if there is one, is filled up with foamed material. 2. Moulded article according to Claim 1, characterised in that the foamed material in the hollow space between the sheets has a lower density than that of the open foamed sheets. . 3. Moulded article according to Claim 1 or 2, characterised in that the internal edge reinforcement is of wood or a wood-like material or other sturdy material. 4. Moulded article according to one or more of Claims 1 - 3, characterised in that the sheets are produced on the basis of polyurethane foam. 5. Moulded article according to one or more of Claims 1 - 4, characterised in that the foamed material in the hollow space between the shejats is polyurethane foam. 6. Moulded article according to one or more of Claims 1 - 5, characterised in that the sheets, which may or may not be profiled, have an average thickness of max. 5 mm. 7. Moulded article according to one or more of Claims 1 - 6, characterised by two flat sheets, one flat sheet and a sheet which is profiled at least on one side, or two sheets profiled on at least one side, said sheets being made of polyurethane foam with a density of 150 - 900 kg per cu. metre, with between them an internal wooden , steely or plastic edge reinforcement, while the hollow space between the two sheets is filled with a polyurethane foam which has a density of 20 - 80 kg per cu.metre. 8. Process for the production of moulded articles, as described in Claims 1 - 7, characterised in that: - the plastic material to be foamed is put on a mould, the material is open moulded under normal pressure, and the set sheet, which may or may not be profiled, is then removed from the mould; - the edge thickness of the sheet is adjusted to the dimensions of the edge reinforcement; - two of such sheets are provided with a preferably wooden edge reinforcement; - a material to be foamed is introduced into the hollow space which may be present between the sheets; - the material to be foamed introduced into this hollow space is allowed to set, while the moulded article is kept in shape by external means. 9. Sheet, which may or may not be profiled, to be used with the moulded articles according to Claims 1 - 7, characterised in that the sheet is made of an open foamed synthetic resin and has an average thickness of max. 5 mm. 10. Sheet, which may or may not be profiled, according to Claim 9, characterised in that the sheet is made of polyurethane foam with a density of 150 - 900 kg per cu. metre.

Inventors: SCHUERMAN PAULUS MAURICE, SCHUERMAN, PAULUS, MAURICE
Applicants: JANSSEN JOHANNA AGNES JOSEPHIN, JANSSEN, JOHANNA, AGNES, JOSEPHINA
Application year: 1985
Main classification: B29C67
IPC codes: B29C44, E06B3