CA2136702C

CA2136702C - Shaped part of plastic foam flocks

Info

Publication number: CA2136702C
Application number: CA 2136702
Authority: CA
Inventors: Bernhard Eder; Franz Reitinger; Hans-Michael Sulzbach; Horst Klahre
Original assignee: CA Greiner and Soehne GmbH
Current assignee: CA Greiner and Soehne GmbH
Priority date: 1993-11-29
Filing date: 1994-11-25
Publication date: 2002-10-08
Anticipated expiration: 2014-11-25
Also published as: EP0657266A1; EP0657266B2; EP0657266B1; DE59408842D1; US6042764A; CZ288981B6; ES2139701T3; CN1112053A; CN1067328C; JPH07195404A; ATE185733T1; CZ294894A3; KR950013674A; US6045345A; CA2136702A1; US5885693A; TW264420B

Abstract

The invention describes a shaped part (2) of plastic foam flocks intercon-nected by a cell structure of a plastic foam of primary material, in particular a soft plastic foam, if required, with at least one covering layer arranged on a surface. The average specific gravity is adapted in different cross-sectional pieces (83, 85) to any application technology requirements.

Description

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SHAPED PART OF PLASTIC FOAM FLOCKS
BACKGROUND OF THE INVENTION
Field of the invention The present invention relates to a shaped part of plastic foam flocks inter-connected by a cell structure of a plastic foam of primary material, in particular soft plastic foam, if required, with at least one covering layer arranged on a surface.
Description of the Prior Art Pursuant to EP-A1-0 350 807, the production of shaped pans from foamed plastic plates is already known. These foamed plastic plates consist of foamed plastic granulates of a soft foamed plastic having a grain size of between 2 mms and 20 mms, and additional filling material such as cork granulates, rubber granulates, chalk, calcium carbonate, hard polyurethane waste or thermoplastic waste plastics having a grain size of between 2 mms and 20 mms, which are foamed in dispersed form into foamed plastics made of primary material. To produce a shaped part from such a foamed plastic plate, the cellular webs and cellular walls of the plastic foam between the individual flocks of the foamed plastic granulates and/or the filling material, and of course also the cellular webs and the cellular walls of foamed plastic granulates and, if necessary, the filling material, are plastically deformed in a permanent way. The deformation of the foamed plastic plates into these shaped parts occurs through the action of heat and pressure on the foamed plastic plates, which are produced by cutting up the foamed plastic block after it ~~~3~'~4~

has been manufactured. In such shaped parts it is difficult to set the density or specific gravities in the individual areas of such a shaped part to desired values.
SUMMARY OF THE INVENTION
It is the object of the present invention to create a shaped part which allows for various different three-dimensional embodiments and a deliberate universal adaptation of the density ratios in the individual cross-sectional areas of the shaped pan. Further-more, the invention comprises a method and a device for the production of such a shaped part.
The problem of the invention is solved in that the average specific gravity can be adapted in different cross-sectional pieces to any application technology require-menu. Thereby, it is advantageous that the specific gravity in the various cross-sectional pieces of the shaped part can already be adapted to the respective specific product re-quirements when the mould is filled , i.e. before a cross-linking or a bonding of the flocks takes place by means of the foamed in plastic which consists of primary material. It is possible for example, to achieve a greater strengthening and component stiffness in the fastening region by using a larger quantity of raw material.
The object of the invention can however also be solved on its own in that the average specific gravity of the preset volume pans from different cross-sectional pieces of the shaped part referring to the intial volume, is the same, or the density of the 21~~'~~~

different volume parts is only different by the compression factor of the preset compres-sion in the respective cross-sectional piece. Thereby, it is advantageous to produce shaped parts, which, independently of their spatial deformation and the respective wall thickness in these differing regions or their thicknesses, can present any density ratio or specific gravity. Thus, it is in particular possible, independently of the the varying thicknesses or outline courses of a spatially deformed shaped part, to achieve over its entire cross-section a uniform average specific gravity with relation to a uniform volume.
Moreover, it is also possible in an advantageous manner to deliberately reinforce certain areas of such a shaped element without thermal deformation or cracking by increasing the density with respect to adjacent regions.
An embodiment wherein the average specific gravity in the cross-sectional piece is preferably of between 25 kg/m3 and 1000 kg/m3 is also advantageous because su~ciently resistant shaped parts can be produced through the bonding of the flocks by the primary-material plastic foam.
However, it is also advantageous to design a shaped part wherein the aver-age specific gravity in the different cross-sectional pieces is the same because it is possible to achieve identical deformation and damping units over the whole shaped part.
An adaptation to different stresses is possible by the further development wherein the average specific gravity in the different cross-sectional pieces is different.

An embodiment wherein the predetermined portion of the volume is a frac-tion of the total volume of the shaped part, preferably smaller than 10-6of the volume of the shaped part enables the production of a shaped pan with scarcely measurable differ-ences in specific gravity or density. Furthermore, shaped parts produced in such a way can be used, for example by using recycling material, for example for components having very precise requirements, such as seat paddings for example, because no differences in density can be established purely by feeling.
Furthermore, an embodiment wherein a quantity and/or a weight of the flocks is greater in regions of the cross-sectional piece of the shaped part, which are ad-jacent to each other, when referring to the same volume is also advantageous since, without thermal cracking, i.e. also in a shaped part with low specific gravity, only by the connection of the plastic material formed of raw material, it enables the production of a shaped part with zones having different density or specific gravity, which are distributed over its cross-section or its three-dimensional shape.
However, a variant of an embodiment wherein adjacent regions of a cross-sectional piece with a different density, have a different initial volume, for example initial thickness and that the region with a higher volume or a higher density at the same volume have a higher initial volume, for example an initial thickness is also possible which en-ables a specific supply of a larger quantity of plastic foam flocks into those regions which should have a higher density. Thus, differently compacted regions of a shaped part or which have a different speck gravity, can be produced in a simple way. In particular, 2136'~~~

the production of such shaped parts having areas with differing densities or varying spe-cific gravities will not require a further processing step, such as a compaction or cracking process, and in spite of the greater density the production of zones which are elastically resilient before and after the process, can also take place in cross-sectional areas or re-gions with greater density.
An embodiment wherein the shaped pan is formed in one piece allows for the production of a shaped part in one operating step if in the individual areas a different density or a different specific gravity, for example a higher speck gravity is required, and adhesive layers can be saved. In addition, by a one-piece production, a shaped part can be produced from a mould which holds also appropriately well together.
However, a further development wherein in the regions of a cross-sectional piece, which are immediately adjacent to each other, the density is different at the same thickness is also advantageous, because shaped parts can be produced having different density but identical thickness, in the regions which are directly adjacent to one another, so that for example in seat paddings, the region to which the main weight of the user is applied, i.e. in the region of the backside, a higher resistance against deformation can be applied than in the directly adjacent areas, so that the paddings produced from shaped parts according to the invention can be used without mod~cation of the construction of the seat frame.
But an embodiment wherein between 70% and 90%, preferably 85% of the 213~'~fl~

volume of the shaped part is fomted by flocks of plastic foam is also advantageous be-cause it allows for a cost-effective production of such shaped parts, in particular when the flocks are made of waste material or recycling material. In addition, when flocks of plas-tic foam are predominantly used, a presettable elasticity of the shaped part can be achieved whereby the latter is particularly suitable for seat paddings.
The embodiment wherein the flocks of plastic foam, in particular of used or recycling material, have a specific gravity of between 20 kgrm3 and 250 kg/m3, prefer-ably 50 kg/m3 to 150 kg/m3allows for the production of shaped parts with a lower specific gravity, which however, have the advantage of a highly elastic resetting behav-iour.
By a variant of an embodiment wherein between 10% and 20% of the weight of the shaped part consists of a synthetic material of primary material, in particular of a plastic foam the weight of the shaped part is not disadvantageously increased by the plastic material used to bond the flocks among themselves and for the shaped part, since the portion of the plastic material provided for the bonding is rather small.
A su~ciently strong connection between the flocks and thereby a good ad-hesion of the latter and a resistant shaped part, is achieved by an embodiment wherein the plastic produced from primary material has a specific gravity of between 800 kg/m3 and 1200 kg/m3 because the primary material having this specific gravity creates a strong holding force between the flocks.

_7_ Due to the good adhesion properties the use of a primary material wherein the primary material consists of polyurethane, in particular a polyurethane foam is also advantageous.
In an embodiment wherein the primary material is formed by a soft foam, in particular a hot-moulded foam the elasticity of a shaped part can be preset at very high values.
In a further embodiment the flocks of plastic foam are interconnected by a cell structure of primary material good bonding of the flocks can be achieved, so that the latter cannot be easily detached from the surface of the shaped part, and on the other hand, due to the elasticity inside the individual flocks, and also the elastic deformation of the cellular structure which is possible when placed under pressure, a sufficient elasticity of the shaped part can still be achieved, which allows for the use of the latter also in a region of highly stressed seats, for example in vehicles, trains, aircraft or the like.
A further development wherein the flocks of plastic foam are embedded in the cell structure of the plastic foam in an elastically compressed state which, with respect to their free-rising foam volume has a smaller volume is also advantageous, whereby due to the pre-compression, an appropriate modification of the resilient properties of the flocks is achieved and thereby of the elastic properties of the entire shaped part, in par-ticular the resilience behaviour of the shaped part can thereby be adapted in a simple manner to the different requirements.

~13s7oz _g_ By a variant of an embodiment wherein in a more compacted region the portion of raw material or primary material, is proportionally higher with respect to the volume than in an adjacent region which is less compacted besides higher suength due to the larger number of flocks, a stronger consolidation and bonding of the flocks can be achieved, and thereby a zone which can be stressed to a higher degree in the more com-pressed region of the shaped part. Thereby, it is possible in most cases without inserting additional shaped parts or reinforcing elements to fix the shaped parts in these regions which are more compressed or to arrange for fastening means.
According to the form of an embodiment wherein the flocks of plastic foam have a granulate or flock size of between 2 mm and 20 mm, preferably 5 mm to 10 mm, a partial compression or the formation of hard zones can be prevented even when the speck gravity or the density of these flocks is relatively high, and moreover, the adhe-sion of the shaped part or its tensile strength is essentially predetermined by the cellular structure produced from the raw material, and any ripping or bursting open of the shaped part in the region of larger enclosures in the shaped part can be avoided.
A further development wherein the flocks of plastic foam are held or em-bedded in a predeterminable three-dimensional shape in the cell structure of the synthetic material of the raw material, makes it possible to produce shaped parts with any different three-dimensional shape in one operating step without the requirement of thermal crack-mg or a pressing process.

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A further strengthening of the shaped part or a correspondingly beautiful surface design is achieved by a further development wherein with the flocks of the plastic foam in the region of a surface of the shaped part by means of the synthetic material of the raw material, a covering layer is connected by way of a forniing on process, whereby during this kind of production of the shaped part, in spite of the application of a covering layer, a high damping diffusion is possible throughout the shaped part, and no separate adhesive layer is required in order to fix the covering layer.
However, a further embodiment wherein the flocks of the shaped part have a different hardness, for example hard or medium hard, is also advantageous, since, espe-cially when the different hard flocks are added in an appropriate dosage to the shaped part, the strengthening properties of such a shaped part can be widely varied.
The use of materials wherein the flocks consist of cold and/or hot-moulded foam wastes and/or soft foam wastes, in particular polyurethane is advantageous because a reuse of the various different materials in a mixed form is made possible.
Due to the use of flocks of materials wherein the flocks are formed of soft foam wastes with coatings, in particular textiles or foils, or by polyurethane composite wastes, a high elasticity of the shaped parts can also be achieved if the flocks are coated with textiles and/or foils.
A structure of a shaped part which is secure with respect to height can be z~~s~Q2 - to -achieved if the flocks are produced from cork and/or rubber or, if a portion of these mate-rials is added to the various soft foams or medium hard foams, it is possible to adapt a hardness of a shaped part to various purposes of use, such as noise damping or panelling elements in motor vehicles or the like.
A further development wherein to the flocks, thermoplastic wastes and/or natural and/or synthetic fibres with different lengths are added in a predetermined quan-tity, makes it possible by adding a small portion of such materials to vary the specific gravity of the shaped parts in a simple manner, whereby by adding natural and/or syn-thetic fibres an even better connection in the various regions of the shaped part can be achieved, since these fibres can be used as a kind of tension bands and for a larger-surface connection of zones in the shaped part that are further spaced apart from one another.
An adaptation with respect to strength of the shaped part, to various sitting parts is made possible by an embodiment wherein inside the shaped part and/or in the re-gion of its surfaces, reinforcement elements, for example plates, foils, lattices, nets, fabric of synthetic or natural materials, in particular metal, graphite, glass or the like, are ar-ranged and are embedded in the flocks or in the filling materials.
Moreover, the invention comprises a method for the production of a shaped part of flocks of foamed plastic, in particular a recycling plastic foam in which the flocks of recycling plastic are mixed in a predetemiinable range of sizes and/or with dif ferent hardnesses in a predetemiinable mixing ratio, whereupon the flocks of plastic foam 2i36'~0~

are mixed with a liquid raw material of a synthetic material and are coated on their sur-face, and then are fed into the mould and are bonded to a continuous cell structure, in particular for the production of a shaped part according to one of the claims 1 to 27.
This method is characterized in that the presettable quantity or mass of flocks of synthetic material and/or filling materials which are mixed with the raw material under a predeterminable pressure, is blown into a mould cavity which is closed from all sides and provided with ventilation openings for the flowing out of a gaseous media, and said mould cavity being filled with the flocks andJor filling materials, whereby under the application of pressure and/or temperature and/or water vapour, the reaction of the raw material is triggered, in particular the plastic foam is produced and that, if required, after a drying process the shaped part is taken out of the mould cavity. This method is advan-tageous because when the material for the production of the shaped part, in particular flocks of different plastics or filling materials, is introduced into a closed cavity, it leads to an evenly compressed filling due to the introduction by an air stream and thereby to a tight uniform embedding of the materials which are introduced approximately by floating within the air stream. Thereby, the shaped parts have a uniform density over their entire cross-sectional area . Thus, it is also possible to fill mould cavities with different spatial designs or different thicknesses, widths or lengths with an identical quantity of flocks or filling materials having an approximately identical density . Thereby, shaped parts with properties, such as noise damping properties or strengthening values, which are approxi-mately identical over their entire cross-section, can be achieved. This was not always possible up until now when flocks and filling materials were placed or poured into an open mould because it led to an uneven displacement of flock mass and filling materials.
The method however, can also be realized by processing steps wherein the mixture quantity from the intermediate storage tank given to the weighing device, is only slightly between 3 and 15%, preferably between 5% and 10% above the quantity, which is to be filled into the mould for the production of the shaped part and that by means of the control by the weighing device, a mixed quantity which corresponds exactly to the filling weight is aansferred with the conveyer to the conveyer, wherein it is possible to produce shaped parts having a density which is kept within strict limits.
By features wherein the volume of the mould cavity after it has been filled with flocks and/or filling material, is reduced in the partial regions of the mould cavity and wherein the reaction of the raw material is triggered thereafter, it is further possible without subsequent thermal deformation or other pressure or heat treatment to produce shaped parts, which, seen across their cross-section are produced from the same base ma-terial with differently tight or strong areas. Thereby, also at densities which cannot be achieved anymore when blowing in the flocks and filling materials during introduction, by compressing loose or non-connected flocks or filling materials, a higher specific grav-ity can be achieved, if required, also over the entire three-dimensional shape of the shaped part, and there is virtually no effect on the connecting structure of the flocks and filling material in a disadvantageous manner since the construction of the cell structure holding the individual flocks and filling materials together, or connecting them to one an-other, is only occurring during the final phase of the compressed form. Thus, by applying such a method it is possible to produce shaped parts with this type of flocks which are tightly linked and which can be more stressed.
By proceeding in a way whereby a volume of a mould cavity for a higher compacted region of a shaped element is larger than for a region having a lower density, the density of the specific gravity or the strength of individual areas of the shaped pan can only be determined in a simple way by an increase in volume when the flocks or fill-ing materials are introduced. Thus it is possible by arranging a plurality of displaceable mould surfaces within the mould cavity to produce rapidly and easily, differently formed shaped parts.
Conveyance within an air stream wherein the mixture of flocks and filling materials, is brought into the mould cavity by a conveying blower allows for an evenly tight filling of the mould cavity with flocks or filling materials.
In a process wherein flocks or filling materials taken from the receptacles if required, are supplied to the weighing tank after appropriate size reduction and accord-ing to the desired mining ratio, an appropriate quantity of different flocks is taken from the receptacles, whereupon this mixture of flocks and/or filling materials is conveyed to a mixing device in which it is mixed with liquid and/or pulverulent raw material in receiv-ing tank and thereafter a predetermined quantity of flocks and/or filling materials is supplied, in particular by a control system to an intermediate storage tank, whereby the predosed quantity of flocks and/or filling material is transported by a conveyer to a re-2136 '~02 ceiving hopper or an inlet of a conveying blower and is blown by means of the latter into the mould cavity, it is advantageous that any composition of flocks and filling materials can be achieved in a simple way and that due to an exact determination of the quantity to be filled with respect to the mould cavity, a uniform thickness and/or density can be achieved as desired during the filling process.
By a method wherein the gas used for the conveying blower to transport the flocks and/or the filling materials, in particular air, is led out through ventilation open-ings in the mould surfaces of the mould, it is advantageous that an appropriate flow-away velocity of the gas or the air, which is used to transport the filling materials, can be sim-ply preset and thereby also the degree of filling or the state of floating, in which the flocks or filling materials are held in the gas or air.
By a method wherein the mould cavity has been filled through these venti-lation openings the reaction means, in particular, vapour is supplied in order to cure the raw material, the blocking of the ventilation openings during the reaction process is pre-vented, which , if required, are also filled with parts of the raw material during the filling process, whereby an immediate self-cleaning of the ventilation opening sets in.
To proceed in a manner wherein before the flocks ( 10, 11 ) and/or the fill-ing material is introduced into the mould cavity (28) in the region of the mould surfaces (33 to 36 and 46) or the mould cavity (28), reinforcement elements are inserted and posi-boned and that after the flocks ( 10, 11 ) or shaped parts (2), however, before the complete zm~7oz - IS -reaction of the raw material (16, 17), the holding parts of the reinforcement elements are removed from the mould cavity (28) is also advantageous since maintenance and produc-tion costs of the shaped part can be kept at a minimum.
Moreover, the invention comprises also a device for the production of a shaped part with several receiving tanks for parts or flocks of plastic foam of a reducing device, in particular arranged downstream of the receiving tank far parts or flocks, which is associated with a weighing tank the outlet of which ends into a mixing device, in which pipes from receiving tanks of the raw material are also ending.
This device is characterized in that the mixing device is followed by an in-termediate storage tank which is provided with a weighing device and which is connected by means of a conveyer, for example a conveying blower or a spiral conveyer with an inlet or a receiving hopper of a conveying blower which , on occasion, is connected with a supply line that can be coupled with a mould cavity. In this installation it is advanta-genus that the mixing of different flocks from different parts, takes place in the same operating step than the mixing with the raw material mixture, and that any intermediate storage or the manufacture of a semi-finished product is prevented. Since the charge weight of the shaped part can be determined before the introduction into the mould cav-ity, the density of said part can be easily predetermined. By means of the conveying blower it is then achieved that the mould cavity can already be closed before the flocks or the raw material coated with flocks or raw materials are introduced, which makes a regu-lar tight introduction and embedding of the latter in the mould cavity possible over the 2136'~0~

entire cross-section.
By virtue of an embodiment of the device wherein the mixed quantity which is given from the intermediate storage tank into the weighing device, is only slightly, preferably between 5% and 10% above the quantity to be filled into the mould and wherein the conveyer which is associated with the weighing device transfers the mixed quantity to the conveyer until the filling weight is reached, whereby this process is monitored by a weighing device, it is possible due to the intermediate storage tank to bal-ante out any differences in weight which may occur during the transport, so that it can be ensured that there is always a sufficient quantity of the mixture available for conveyance by means of the conveying device to fill the mould during the production of a shaped part.
By an embodiment of the mould wherein the ventilation openings in the mould surfaces of the mould cavity can be connected alternately with ambient air, a vac-uum pump or a feeder for a reaction means, such as vapour, in particular dry steam having temperatures of between 160°C and 180°C and the selected use of the ventilation openings for the flowing away of the conveying gases, in particular the air of the convey-ing blower, said openings can be kept open or cleaned immediately even if raw material passes through them and in addition, they can be used to position covering layers or rein-forcement elements or insert parts in the region of the mould surfaces.
Finally, by an embodiment wherein in the vicinity of the mould surfaces of the mould, reinforcement elements are arranged in the mould cavity which are adjustable holding parts, it is possible to achieve different densities already before the cross-linking or the connection of the individual flocks by means of the foamed plastic of primary material in the cross-sectional areas immediately adjacent to one another in a shaped part, so that it is thereby possible to produce in one working step components having identical thicknesses but different densities.
According to one aspect of the invention, there is provided a three-dimensional shaped part having a predetermined volume and comprising at least one first portion having an equal density throughout the volume thereof and comprising a plastic foam of a primary material having a cellular structure and plastic foam granules interconnected by the cellular structure of the plastic foam, and at least one second portion having an equal density throughout the volume thereof, the second portion being adjacent the first portion and comprising a plastic foam of a primary material having a cellular structure and elastically nonthermally precompressed plastic foam granules interconnected by the cellular structure of the plastic foam, and the density of the second portion being greater than the density of the first portion, and 70% to 90% of the volume of the shaped part being formed by the plastic foam granules.
According to another aspect of the invention, there is provided a method of producing a three-dimensional shaped plastic foam part, comprising the steps of mixing plastic foam granules having at least one property selected from the group consisting of a predetermined range of sizes and different hardness in a predetermined mixing ratio to obtain a mixture of the plastic foam granules, mixing the mixture of the plastic foam - 17a granules with a liquid primary material until the granules are coated with the liquid primary material and a mixture of coated plastic foam granules is obtained, storing the mixture of the coated plastic foam granules in an intermediate storage tank, conveying a preset quantity of the stored coated plastic foam granules from the intermediate storage tank to a mold cavity of a mold closed on all sides, the stored coated plastic foam granules having been weighed to provide a quantity thereof which is between 3% and 15%
above the quantity required to fill the mold cavity, and the weight of the stored coated plastic foam granules having been so controlled that it corresponds exactly to that of the quantity to fill the mold, reducing the volume of the mold cavity at least in partial regions thereof after it has been filled with the mixture of coated plastic foam granules, triggering a reaction of the liquid primary material by applying pressure and heat until a continuous cellular structure of plastic foam has been formed and the plastic foam granules have been interconnected by the cellular structure of plastic foam after the volume of the mold cavity has been reduced at least in partial regions thereof, venting gaseous reaction media from the mold cavity through openings in the sides of the mold, and removing the three-dimensional shaped part from the mold cavity.
According to yet another aspect of the invention, there is provided a method of producing a three-dimensional shaped plastic foam part, comprising the steps of reducing plastic foam to granules of a predetermined range of sizes, mixing the plastic foam granules in a predetermined range of sizes in a predetermined mixing ratio to obtain a mixture of the plastic foam granules, the mixture of the plastic foam granules having been weighed to obtain the predetermined mixing ratio, conveying the weighed mixture of the plastic foam granules to a mixing device to mix the granules with a liquid primary - 17b -material until the granules are coated with the liquid primary material and a mixture of coated plastic foam granules is obtained, supplying a controlled quantity of the coated plastic foam granules to an intermediate storage tank to obtain a preset quantity of the mixture of coated plastic foam granules, conveying the preset quantity of the mixture of coated plastic foam granules to an inlet of a conveying blower and blowing the mixture into a mold cavity of a mold closed on all sides, reducing the volume of the mold cavity at least in partial regions thereof after it has been filled with the mixture of coated plastic foam granules, triggering a reaction of the liquid primary material by applying pressure and heat until a continuous cellular structure of plastic foam has been formed and the plastic foam granules have been interconnected by the cellular structure of plastic foam after the volume of the mold cavity has been reduced at least in partial regions thereof, venting gaseous reaction media from the mold cavity through openings in the sides of the mold, and removing the three-dimensional shaped part from the mold cavity.
According to a further aspect of the invention, there is provided a method of producing a three-dimensional shaped plastic foam part comprising the steps of mixing plastic foam granules having at least one property selected from the group consisting of a predetermined range of sizes and different hardness in a predetermined mixing ratio to obtain a mixture of the plastic foam granules, mixing the mixture of the plastic foam granules with a liquid primary material until the granules are coated with the liquid primary material and a mixture of coated plastic foam granules is obtained, feeding a preset quantity of the mixture of coated plastic foam granules into a mold cavity of a mold closed on all sides, introducing reinforcement elements in the mold cavity before the mixture of coated plastic foam granules has been fed into the mold cavity, and positioning the reinforcement elements in the mold cavity by holding parts, reducing the volume of the mold cavity at least in partial regions thereof after it has been filled with the mixture of coated plastic foam granules, triggering a reaction of the liquid primary material by applying pressure and heat until a continuous cellular structure of plastic foam has been formed and the plastic foam granules have been interconnected by the cellular structure of plastic foam after the volume of the mold cavity has been reduced at least in partial regions thereof, removing the holding parts from the mold cavity before the reaction ofthe liquid primary material has been completed, venting gaseous reaction media from the mold cavity through openings in the sides of the mold, and removing the three-dimensional shaped part from the mold cavity.
According to yet a further aspect of the invention, there is provided an installation for producing a three-dimensional shaped plastic foam part from plastic foam granules bonded together by foaming a liquid primary material, comprising a plurality of tanks respectively receiving the plastic foam granules and the liquid primary material, a device for reducing the plastic foam granules to a predetermined size, conduit means connecting the reducing device to respective ones of the tanks receiving the plastic foam granules, a weighing tank having an inlet arranged to receive the plastic foam granules of predetermined size from the reducing device and an outlet, a device for mixing the plastic foam granules of predetermined size with the liquid primary material, further conduit means connecting the mixing device to respective ones of the tanks receiving the liquid primary material and to the outlet of the reducing device, an intermediate storage tank comprising a weighing device and arranged to receive the plastic foam granules mixed with the liquid primary material, a mold having a mold cavity, and a supply line 17d connecting the intermediate storage tank to the mold cavity, the supply line comprising a conveying device having an inlet and a conveying conduit connected to the intermediate storage tank, the conveying conduit being connectable to the conveying device inlet.
BRIEF DESCRIPTION OF THE DRAWINGS
Hereinafter, the invention will be explained in further detail, by way of ex-ample only, of the accompanying drawings, in which:
FIG. 1 shows an installation for the production of a shaped part according to the invention, in a simplified, diagrammatic representation;
FIG. 2 shows a mould for the production of a shaped part, in a simplified, diagrammatic representation;
FIG. 3 shows the mould according to FIG. 2, in a front view, in a section taken along the lines III-III in FIG. 2 and in a simplified, diagrammatic representation with a covering layer introduced into the mould and an inner chamber partially filled with flocks of synthetic material;

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FIG. 4 shows the mould according to FIGS. 2 or 3, with form surfaces adjusted for pre-compression of the shaped part, in side view, in section and in a simpli-Pied, diagrammatic representation;
FIG. 5 shows the mould according to FIGS. 2 to 4 with further mould surfaces adjusted for the pre-compression of the shaped part, in front view, in section and in a simplified, diagrammatic representation;
FIG. 6 shows the final pre-compressed shaped part in the mould ac-cording to FIGS. 2 to 5 and after reaction of the liquid synthetic material in a simplified, diagrammatic representation;
FIG. 7 shows another embodiment of a mould for a shaped part ac-cording to the invention, in side view, in section and in a simplified, diagrammatic representation;
FIG. 8 shows the mould according to FIG. 7 with flocks of foamed plastic compressed to a different degree in different areas;
FIG. 9 shows a shaped part in accordance with the invention accord-ing to FIGS. 7 and 8 in a simplified, schematic, diagrammatic representation.

2~3~~oz DETAILED DESCRIpIZON OF PREFERRED EMBODIMENTS
FIG. 1 shows an installation 1 for the production of shaped parts 2. Said installation comprises several receptacles 3, 4 and a receiving tank 5 for different parts 6 of foamed plastic 7, 8, preferably also waste from foamed plastics for recyling.
The pans 6 contained in the individual receptacles 3, 4 may consist of dif-ferently cured plastic foams or plastic foam with or without coatings or covering layers or the like, for example. The materials used can be preferably individual or in any presetta-ble ratios of PUR (polyurethane) soft foam waste materials, PUR cold and/or hot foam mould wastes, PUR-soft foam waste material coated or textile- and/or foil-backed, PUR-composite foam waste material, but also rubber or cork granulates. Here, it is possible that in addition, thermoplastic waste and/or natural and/or synthetic fibres of different length are added to the above mentioned materials in order to produce the shaped parts 2.
If waste of foamed plastics is provided, it may originate from production waste, or parts 6 may of course also consist of already used, disassembled parts of synthetic material foams. It is, of course, also possible to reduce plastic foams of primary material, i.e. plas-tic foams which have been produced particularly for this purpose, to the appropriate granulate or flock size.
It is of course also possible that larger parts are contained in these recepta-cles 3, 4, as they occur for example when cutting shaped parts, such as paddings, matresses, noise damping elements or panelling elements used in the car industry, so that z~~s7oz these pans of synthetic material or plastic foams 7, 8 which are to be recycling, are torn up, cut or somehow otherwise reduced to a preset granulate size of between 3 mms and 20 mms, preferably 5 mms to 10 mms, before they are stored in the receptacles 3, 4.
Generally, the parts 6 are reduced to the desired granulate or flock size be-fore they are stored in the receptacles 3, 4, by means of reduction devices 9, for example a willowing machine, a cutter or disintegrator, a mill or the like, so that the flocks 10, 11 of various plastics or plastic foams 7, 8 are already in the receptacles 3, 4.
If, instead of them however, pans 6 in their respective size are in the receptacles 3, 4, a willowing ma-chine, a cutter or disintegrator or the like may be located downstream of these receptacles 3, 4, as schematically indicated. The flocks 10, 11 are then transported from the recepta-cles 3, 4 in a portion corresponding to the respective mixing ratio, for example by means of pneumatic conveyance to a weighing tank 12. The regulation of the amounts of indi-vidual flocks 10, 11 can take place by control valves 13, which are monitored and activated by a central control system 14.
The premixed charge of waste or flocks 10, 11 of new material or other materials, which, if required, can be arranged in their own additional receptacles 3, 4 which are not shown, is then for example mixed by a pneumatic conveyance of a mixing device 15, for example is supplied to a rotary mixer, in which it is mixed with a liquid raw material 16 or 17 such as a polyalcohol and an isocyanate, which is supplied in quan-tides regulated by means of control valves 18 depending on the control system 14.

213~'~0~

If the raw materials 16, 17 which are supplied by the receiving tanks 5 are suffiently mixed with the flocks 10, 11 in the mixing device 15, or the mixture is so good that these flocks 10, 11 are essentially coated continuously over their entire surface with this liquid raw material, the flocks 10, 11 which are coated with the liquid raw material of the synthetic material or foamed plastic, are brought to an intermediate storage tank 20 by means of a conveyor 19, for example with a blower or a spiral conveyor. This intermedi-ate storage tank 20 can be constructed as a weighing tank 12, that is to say, to determine the weight it can be connected with a measuring device, which is generally also con-nected with the control system 14 downstream of which a weighing device 21 is arranged.
The conveyor 19 of the mixing device 15, which for example is indicated only schemati-cally, can consist of a feed screw but also of a gravity conveyance, for example a stopper 23 which is adjustable by means of an adjusting device 22 in the outlet region of the mix-ing device 15 which feeds the flocks 10, 11 which are mixed with the raw material 1b, 17 into the intermediate storage tank 20.
In this intermediate storage tank 20, a mixed quantity is preferably filled in, which is enough to produce the greatest shaped part with this installation. But also any multiple of this quantity can be stored in the intermediate storage tank 20.
Depending on the desired weight of the parts by using the corresponding conveyer 19 or the stopper 23 which is adjustable by the adjusting device 22 , a quantity of flocks 10, 11 mixed with the raw material 16, 17 can be fed from this intermediate storage tank 20 to the weighing device 21 arranged downstream of the intermediate stor-2136'02 age tank 20, which is generally 3 - 15%, preferably of between 5 and 10% above the final weight of the parts of a shaped part to be produced. The supply of the mixture from the intermediate storage tank 20 into the weighing device 21 is also monitored by a schemati-cally indicated measuring device which transfers the data to the control system 14, and the conveyance of the mixture from the intermediate storage tank 20 is interrupted when the predetermined weight is reached.
From the weighing device 21 it is possible to approach the adjustment drive 22, for example by a pneumatic cylinder-piston arrangement or an electric stepping motor or the like via a corresponding control by means of the control system 14 in order to move the stopper 23. Taking into account the reduced weight - which is reduced in the weighing device 21 by conveyance and monitored by the measuring device - of the mix-tore of flocks 10, 11 coated with raw material 16, 17, the conveyance, by means of a conveyer 24 an anged downstream of said weighing device, is continued to such a point until a quantity of the mixture con esponding to the predetermined weight required for the production of the shaped part is removed from the weighing device 21.
The conveyer 24 located downstream which transfers the mixture of flocks 10, 11 formed of raw material 16, 17 to a receiving hopper 25 of a conveying blower 26 arranged downstream thereof, can be formed by a spiral conveyer or a blowing conveyer.
A drive 27 of the conveying blower 26 is also conuolled by the control system 14.
After a further stopper 23 located downstream of the conveying blower 26 213~"~0~

and activated by the control system 14, or an adjustment drive 22 connected to the latter has been opened, the mixture of flocks 10, 11 and raw material 16, 17 can now be blown into a mould cavity 28 of a mould 29 which consists of a lower mould part 30 and an upper mould pan 31.
The control of the supply of the flocks 10, 11 which are coated with the liquid raw material can also take place via a control valve 32, for example a stopper 23, which can also be controlled by a control system 14 in the same manner as the conveying blower 26.
In all or some of the individual mould surfaces 33 to 36, admission open-ings or ventilation openings 37 can be arranged, at least in the mould surface 36 opposite the inlet-opening, which connects the mould cavity 28 with ambient air, or, as schemati-tally indicated, with an exhaust pipe 38.
Into the exhaust pipe 38 runs a feeder 40 also via a control valve 39, which is activated by the control system 14, by means of which for example water vapour, pref-erably dry steam at a temperature of 160°C to 180°C, or another reaction means, for example of a heat exchanger 41 or a steam station is fed into the exhaust pipe 38. This takes place for example in that the exhaust pipe 38 is closed by a stop valve 42, which is activated by the control system 14, whereupon between this stop valve 42 and the mould cavity 28 this reaction means or vapour is introduced by the feeder 40 and after it flowed through the mould cavity 28, can flow out of the ventilation openings 37 which are not closed. Not only the air brought into the mould cavity 28 through these ventilation open-ings 37 during the introduction of the flocks 10, 11 - according to the schematically indicated arrows 43- , can be removed but the water vapour, also indicated schematically by an arrow 44 , can be introduced into the mould cavity 28 and also removed therefrom.
FIGS. 2 to 6 show the mould 29 in a simplified, diagrammatic representa-tion but proportionally enlarged.
Thus, it can be seen from this illustration that the flocks 10, 11 can be in-troduced by a supply line 45 into the mould cavity 28, and in this case, the ventilation openings 37 are arranged on the sidewalls parallel to the region of the mould surfaces 34 and 46, so that the air coming in with the mixture of flocks 10, 11 can flow out into the open through these ventilation openings 37 or into the exhaust pipes described by way of example in FIG. 1.
As can be seen better from the representation in FIG. 3, the flocks 10, 11 are pulled into the mould cavity 28 by the air flow indicated by the arrows 43, and are deposited therein or on the mould surfaces 34 to 36 and 46, as schematically indicated. It can be seen further from the representation that each of the flocks 10, 11 is coated with a surrounding coating 47 of the mixture of raw materials 16, 17 which is still liquid to form the plastic foam.
Generally, between 70 and 90%, preferably 85% of the volume of the 2~.~6'~0~

shaped part 2 to be produced consists of flocks 10, 11 of plastic foam from raw material 16, 17. 10 to 20% of the weight of the shaped part 2 are formed by the plastic foam of primary material or raw material 16, 17. The flocks 10, 11 of plastic foam 7, 8 have in general a specific gravity of between 20 kg/m3 and 250 kg/m3, preferably 50 to kg/m3. The specific gravity of the plastic foam which has been produced from raw mate-rial 16, 17 is of between 800 kg/m3 and 1200 kg/rn3 whereby the latter is preferably half stiff or half hard.
Furthermore, FIG. 3 also shows that before the Clocks 10, 11 are intro-duced, for example onto the mould surface 33, i.e. the floor of the mould 29, a covering layer 48, for example a batt or knitted material, fabric, lattice, net of natural or synthetic fibres, can be inserted preferably into a deepened part of the mould surface.
In this case, also when the ventilation apenings 37 are triggered separately in the region of the individual mould surfaces 33 to 36 and 46 it is possible to use these ventilation openings 37 by applying a vacuum, for example by means of a vacuum pump 49 and by flaps 50 which can be controlled separately from the control system, in order to hold the covering layer 48 tightly. The vacuum pump 49 which is connected to the ex-haust pipe 38 is also shown schematically in FIG. 1.
In particular if the covering layer 48 is permeable to air, a portion of the conveying air can be simultaneously sucked up by the vacuum pump 49 or otherwise, can flow through the remaining ventilation openings 37 according to arrows 43 out of the m3s~~~

mould cavity 28.
When the mould cavity 28 is filled with flocks 10, 11 in a uniform manner from the back towards the front, the conveying blower 26 is switched off and the supply line 45 is closed by means of the stopper 23, if required, the conveying blower 26 of the mould 29 can be uncoupled, in particular if said mould is arranged on a turntable or on a conveyer for loading of different work stations.
It is essential for the present method or manufacture of the shaped part 2 that the volume of the mould cavity 28 is about 10 to 50%, preferably 20% to 30% larger than the volume of the finished shaped part 2. This general precompression of the shaped part 2 occurs in such a way that the individual mould surfaces 33 to 36 and 46 depending on the various shaped parts 2 to be produced, are displaced into different positions from their initial position, either individually on different individually differing mould surfaces 33 to 36 and 46 or on all of them.
Thereby, the individual mould surfaces 33 to 36 and 46 can consist of sev-eral parts. In the present examples of an embodiment in FIGS. 3 to 6 only the mould surfaces 33, 35 and 46 are designed in several parts.
This way, the mould surface 33 consists of a surrounding mould ring 51 and an adjustable central part 52, which, as indicated schematically, can be activated by an adjustment drive 53, for example a pneumatic or hydraulic cylinder, which, as indi-2m~~oz Gated schematically, can be supported by a mould frame 54, by triggering a control system 14 or energy sources activated by the latter, such as compressed-air compressors or hydraulic pumps. The same way, the mould surface 35 consists also of a sturounding mould ring 51 and a central part 52, which can be adjusted in the same way, which is also adjustable via a schematically indicated adjustment drive 53 with respect to the mould ring 51, which in the same way as the mould ring 51 of the mould surface 33 is held in a mould frame 54. The mould surfaces 46, on the other hand, are constructed in one piece and the mould surface 34 is also composed of a central part 55 and two lateral parts 56 and 57, as can be better seen from the representation in FIG. 6, whereby the lateral parts stand permanently in the mould frame 54 and the central part, as can be seen from FIG.
3, is adjustable with respect to the other mould elements by means of an adjustment drive 58.
As it is apparent from the course of processes shown in FIGS. 3 to 5, the mould surfaces 46 with the adjustment drives 59 associated therewith, are displaced from their initial position drawn in FIG. 5 by broken lines, which corresponds to the position in FIG. 3, into the compressed adjustment position, drawn in full lines. A
distance 60 be-tween these two mould surfaces 46 which are mutually opposed, corresponds precisely to a width 61 of the central part 52 of the mould surface 33 exactly parallel to the distance 60.
Depending on the ratio between an initial width 62 and the distance 60, a different compression ratio or a different compression of the flocks 10, 11 or the granu-21~fi70~

late which are arranged in the mould cavity 2 and are still coated with liquid plastic is achieved.
After this compression process, as shown in FIG. 4, the central part 55 of the mould surface 34 is displaced from the position shown by broken lines in FIG. 4 and by full lines in FIG. 3, into a compressed position which is now shown in FIG.
4, by means of the adjustment drive 58. At the same time the mould surface 36 or a central part 55 equivalent to the mould surface 34 can be adjusted after an appropriate decoupling of the supply line 45 from the conveying blower 26, from a position shown in full lines in FIG 3. into a compressed position drawn in full lines in FIG. 4. By the displacement of these central parts 55 relative to the mould surfaces 46, which have been transported to-gether, a length 63 of the shaped part 2 is now reduced to a predetermined length of the central parts 52 of the mould surfaces 33 and 35. Due to the difference between the in-itial length 64 of the mould cavity 28 between the mould surfaces 34 and 36 and the finished length 63 a further compression factor of the shaped part 2 is also established.
Finally, as can be seen from FIG. 6, the further compression of the non-solidified shaped body, i.e. of the flocks 10, 11 which can still be moved relatively to-wards each other with their coating 47, can achieve an intial height 65 of the mould cavity 28 to a height 66 by transporting together the central parts 52 of the mould surfaces 33 and 35.
With this final adjustment process the article-specific compaction process is terminated. The original volume is reduced by these supply or adjustment steps of the individual mould surface parts or the central parts 52, 55 and the mould surfaces 46 for the desired percentage of about 10 to 50%.
Thereby, it is to be noted that an average weight of the shaped parts 2 is between 20 kg and 300 kg. The adjustment occurs by means of adjustment drives, which can be constituted by hydraulic or pneumatic cylinders as described hereabove.
The se-quence of the displacement of the individual mould surfaces or mould surface parts, such as the central parts 52 or ~S and the mould surfaces 46, have been explained only by way of example in FIGS. 3 to 6. The successive movements of the individual mould surfaces or their central parts or other shaped parts, can be set differently depending on the article or the final hardness achieved or the like in each single shaped part 2. It is also possible that the lifting or adjustment paths of the individual mould surfaces or mould surface parts or the central pans of the latter, can take place at different sizes so that in different three-dimensional directions of the shaped pan 2 different compression values can be achieved, for example through compressions in vertical direction only 15% of the vol-ume and by compression in the longitudinal direction of the component 30% of the volume or by compression in the direction of the width a reduction in volume of about 35%.
After this article-specific precompression, the covering layer 48, which ex-tended initially only over a portion of the initial length 64 and the initial width 62 of the mould surface 33 for example, covers now a surface of the shaped part 2 over its entire 21~~'~02 face as can be seen from FIG. 6.
Thereafter, as already described schematically in FIG. 1, the reaction fluid, for example vapour with a temperature of 160°C to 180°C, in particular dry steam is fed into the mould cavity 28 through ventilation openings 37 or openings which are arranged especially for this purpose. These reaction fluids, in particular vapour or a solvent intro-duces the reaction of the liquid coating 47 or the synthetic material, and this liquid raw material foams up due to an appropriate gas formation and the development of a cell structure of open and/or half open and/or closed cells between the individual flocks 10, 11 for example, as indicated schematically in FIG. 6.
This way, the initially loose flocks 10, 11 are integrated into a soft, me-diem or hard cell structure depending on the desired strength based on the raw material used, and this leads to a strenghtened shaped part 2 having the desired thickness and hard-ness.
After the reaction of the coating 47 and the development of a correspond-ing cell structure in the shaped part 2, the mould 29 can be conveyed to a drying station, especially if the mould is moved along a mould path in cycles, for example by means of a turntable, whereby hot, dry air is guided through the ventilation openings 37 for example, in order to dry the shaped part after its reaction.
After the shaped part 2 has been sufficiently dried, the corresponding sup-ply openings for this dry air are closed and the mould 29 can be opened and the shaped part 2 can be removed.
Of course, within the scope of the present invention it is also possible to carry out the individual working steps manually, half or fully automatic or to control these steps semi-automatically or automatically by means of an overall control system us-ing a control system 14.
Instead of the mould surfaces 33 to 36 and 46 which consist of several parts, mould surfaces with a plurality of individual mould punches can be used for exam-ple in order to achieve a rapid adaptation of the mould for the production of different shaped parts. The surface or the mould cavity 28 as well as the subsequent individual compression processes can be preprogrammed for the production of the respective articles in an all-automatic manner by an appropriate control programme.
Hence, it is furthermore also possible that the central parts 52 of the mould surfaces 33 or 35 can be provided with any three-dimensional shape on a surface facing towards the mould cavity 28. If this is not favourable for precompression, it is also possi-ble to use first a plane-surfaced central part 52 to precompress the flocks 10, 11 and to replace it by a central part 52 with a particular three-dimensional shape before the reac-tion process or the reaction of the coating 47 or the synthetic material starts, in order to give the shaped part 2 a required spatial deformation during the production process. The short opening and closing can also be used to apply covering layers directly to one or sev-eral surfaces of the shaped part 2, as it is indicated schematically by way of example of the covering layer 4$ covering layers directly onto the shaped part 2 during the produc-tion process on one or several of the surfaces of the shaped part 2, as it is indicated schematically by means of the covering layer 48.
Depending on the raw material 16, 17 to be used which in general is a polyurethane, polyether or polyester foam, which can be adjusted to be soft, medium or hard, a close or open cell structure is formed in which the individual flocks 10, 11 are embedded thereafter.
The advantage of this solution lies in particular in the fact that due to the supply of the flocks 10, 11 by the air stream into a closed mould cavity 28 based on the regular flowing away of the air, a uniform complete filling of the mould cavity 28 is achieved whereby a tighter packing together of the flocks 10, 11 which are elastic and can be deformed under weight load, is eliminated. Since the flocks are keeping their balance during the filling of the mould cavity 28 due to the air stream which is constantly passing through, according to arrows 43, and after the air stream is switched off, due to the raw material of the coating 47 adhere loosely to one another, a production of shaped parts 2 is created also during a series production with a high repetition phase sequence number, which, over its entire cross-section allows for an average specific gravity and uniform distribution of the flocks 10, 1 l, in particular also of the various recycling materials with different specific gravities or coating parts.

2~.3f ~0~

Based on the proceeding mixture of the flocks 10, 11 from the receptacles 3, 4 and the filling weight of the mould cavity 28 ,which can be predetermined in the in-termediate storage tank 20, the basic density being achieved can also be preselected, whereby, if required, it can be additionally influenced by the air stream or the air pressure procuded in the mould cavity 28 by the air stream.When the filling with the flocks 10, 11 in the mould cavity 28 increases, the pressure produces a greater resistance against the air flowing through, and depending on the preselected degree of pressure of the convey-ing air, an equivalent density can be created in the flocks 10, 11 which are located loosely in the mould cavity 28, or in the preformed blank part.
In addition, FIGS. 7 to 9 show that the mould cavity 28 can also be used to produce spatially curved shaped parts 2 as it is shown for example in FIG. 9.
As can be seen further from the representation of the shaped part 2 in FIG.
9, the latter can also be provided with deepened recesses 71, 72.
As illustrated in the moulds used, it is now simultaneously possible by means of a general precompression of the shaped part 2 based on the displacement of a central part 52 of the mould surface 35, to increase the density in the shaped part in the cross-sectional regions in which the recesses 71, 72 are arranged in the shaped part 2.
This occurs in such a way that in the mould surface 35, for example along guide rods 73 by means of adjustment drives 74, for example piston-cylinder arrange-2~.36'~0~

menu activated by a fluid for example, adjustable mould inserts 75, 76 , which by means of setting drives 77, 78 shown in full lines in FIG. 7 are displaceable into a position shown in full lines in FIG. 8.
'Ibis way, as can be seen from the different density of the schematically indicated flocks 10, 11 in FIGS. 7 and 8, the mould cavity 28 is enlarged whilst the flocks 10, 11 which are coated with the raw material 16, 17 are blown in and in the entire mould cavity a filling with identical density is achieved.
In order to achieve in the regions 79, 80 of the shaped part 2 a higher den-siry of the flocks 10, 11 and also of the foam structure of raw material 16, 17 situated therebetween, in addition to the general precompression of the flocks 10, 11 as it is achieved by the adjustment of the central part 52 of the mould surface 35 by means of the adjustment drive 53, or independently thereof . the mould insert 75 and/or 76 can be ad-justed by means of setting drives 77, 78 from a rest position or filling position for the mould cavity 28 drawn in full lines in FIG. 7 into the compression position shown in FIG.

7 by broken lines and drawn in FIG. 8 in full lines.
As it is indicated schematically in FIG. 8 by a tighter layer of the flocks 10, 11, the density is thereby increased in the regions 79, 80 of the mould cavity 28 corre-sponding to the respective insertion depth 81 or 82 which, during the subsequent reaction of the liquid raw material 16. 17 based on the higher density results in an increasingly strenghtened zone in the shaped part 2.

2136'~Q,2 This has for example the advantage, that in this region, fastening elements can be arranged by means of which the shaped part 2, when used as noise insulating mat or inner lining in a vehicle, can be fixed to the body.
The compression can also be arranged to provide the shaped part 2 in its entirety based on the forming with a higher stiffness or strength.
It is, of course also possible, if in this region, in which the recesses 71 and 72 are provided, no greater density of the shaped part 2 is required, that the mould inserts 75, 76 can already be displaced before the flocks 10, 11 are blow in, into a position shown by broken lines in FIG. 7. This leads to the development of a shaped part 2 in which recesses 71, 72 are arranged but this shaped part 2 has then over its entire cross-section an average identical density.
The average, identical density can be found or compared as follows:
The weight of a cross-sectional piece 83 - as shown in FIG. 9 - is deter-mined by a thickness 84 and calculated from the volume and the existing weight, which volume this cross-sectional piece 83 would have at a predefined reference specific grav-ity.
Thereafter, the weight of a further cross-sectional piece 85 having prefer-ably the same thickness 84 is determined, and also from the resulting data, the volume is established for the reference specific gravity used for calculation. The values of volumes, which have been established in this way, refer to an identical reference specific gravity, which is then referred back to a given reference volume, and an identical average density and/or specific gravity is provided if the resulting specific gravity of the reference volume or the density is the same, or not deviating more than +/- 15%, preferably +/-7,5% from one another.
Thereby, it is understood that a comparison of specific gravities refers to the ratios as they occur during the blowing in of the flocks 10, 11 into the mould cavity 28, whereby a larger volume of the mould cavity 28 is created by pulling back the mould inserts 75, 76 or the mould surfaces 33 to 36 and 46. which is filled with flocks 10, 11 of identical density.
The higher compression schematically indicated and shown in FIG. 6 in the regions 79 and 80 of the shaped part 2 is only achieved in that the initially introduced flocks 10, 11 with identical density are partially more compacted by a deliberate volume reduction which of course, also increases the specific gravity removal of due to the re-duced volume. Of course, in this variant of an embodiment, it is also possible not only in the direction of the mould surface 35, but also in the direction of the other mould surfaces 33, 34, 36 and 46 to carry out a precompression. The same way, it is also possible to arrange additional adjustable mould inserts 75 and 76 of any type and configuration, also in the other mould surfaces 33, 34 or 36 and 46.

21~~'~0~

For good order's sake it must be noted at this point, that each of the exam-ples of an embodiment shown or feature combinations characterized in the claims can form their own solution in accordance with the invention. In addition, individual features of the individual examples of an embodiment which are combined with one another in any composition, can also form the object of own solutions according to the invention.
For a better understanding of the effect of the method and the structure of the shaped part 2, individual layers and coatings of the flocks 10, 1 l, the flocks them-selves or the shaped part 2 is unproportionally enlarged and distorted or greatly exaggerated. The same applies also for devices and moulds for the production of such shaped parts, which are mostly shown in a simplified and diagrammatic representation.
As moulding material for the moulds 29, metal alloys especially of epoxy resin or resin-fed, such as moulds cast of aluminium, milled out or in the form by alumi-num plates, as well as of stainless steel or iron plates, can be used for the production of the moulds.
Finally, it must be pointed out that an advantage during the production of the shaped parts 2 of recycling material is achieved by the above described way of proc-essing, in that the old recycling materials at the time when the hardening or reaction of the raw material 16, 17 occurs by means of a hot vapor or hot air, which, can also be soiled, are sterilized by the high temperatures and thereby eliminate any undesired fun-gus, germs or the like.

z~~s7oz In particular, the individual embodiments shown in FIGS. 1; 2 - 6; 7, 8; 9 can form the object of own solutions according to the invention. Relating tasks and solu-tions are apparent from the detailed descriptions of these figures.

Claims

1. A three-dimensional shaped part having a predetermined volume and comprising (a) at least one first portion having an equal density throughout the volume thereof and comprising (i) a plastic foam of a primary material having a cellular structure and (ii) plastic foam granules interconnected by the cellular structure of the plastic foam, and (b) at least one second portion having an equal density throughout the volume thereof, the second portion being adjacent the first portion and comprising (i) a plastic foam of a primary material having a cellular structure and (ii) elastically nonthermally precompressed plastic foam granules interconnected by the cellular structure of the plastic foam, and (iii) the density of the second portion being greater than the density of the first portion, and (c) 70% to 90% of the volume of the shaped part being formed by the plastic foam granules.

2. The shaped part of claim 1, wherein the portions extend along one of the dimensions of the three-dimensional shaped part, the one dimension defining the thickness of the shaped part, and the average density of said portions is between 25 kg/cu.m. and 1000 kg/cu.m.

3. The shaped part of claim 1, wherein the portions extend along one of the dimensions of the three-dimensional shaped part, the one dimension defining the thickness of the shaped part, and a predetermined volume of the portions is a fraction of less than 10 -6 of the volume of the shaped part.

4. The shaped part of claim 1, wherein the portions extend along one of the dimensions of the three-dimensional shaped part, the one dimension defining the thickness of the shaped part, portions having different widths having different initial volumes, the second portion having a larger initial volume at the same volume of the portions.

5. The shaped part of claim 1, wherein the shaped part is formed in one piece.

6. The shaped part of claim 1, wherein the first and second portions are sections extending along one of the dimensions of the three-dimensional shaped part, the one dimension defining the thickness of the shaped part, adjacent ones of the sections of the same thickness having different densities.

7. The shaped part of claim 1, wherein the plastic foam granules have a density of between 20 kg/cu.m. and 250 kg/cu.m.

8. The shaped part of claim 1, wherein the plastic foam of the primary material forms 10% to 20% of the shaped part.

9. The shaped part of claim 1, wherein the plastic foam of the primary material has a density of 800 kg/cu.m. to 1200 kg/cu.m.

10. The shaped part of claim 1, wherein the primary material is polyurethane.

11. The shaped part of claim 1, wherein the plastic foam of a primary material having a cellular structure is a soft plastic foam.

12. The shaped part of claim 1, wherein the proportion of the primary material in relation to the volume thereof is higher in the second portion than in the adjacent first portion.

13. The shaped part of claim 1, wherein the granules have a grain size between 2 mm and 20 mm.

14. The shaped part of claim 1, wherein the granules are embedded in the cellular structure in a predetermined three-dimensional shape.

15. The shaped part of claim 1, comprising a covering layer bonded to a surface area of the shaped part.

16. The shaped part of claim 1, wherein granules of different hardness are interconnected by the cellular structure.

17. The shaped part of claim 1, wherein the granules are comprised of plastic foam waste.

18. The shaped part of claim 17, wherein the granules of plastic foam waste have a surface coating.

19. The shaped part of claim 1, further comprising fibers of thermoplastic plastic waste incorporated in the cellular structure.

20. The shaped part of claim 1, wherein the second portion extends along one of the dimensions of the three-dimensional shaped part, the one dimension defining the thickness of the shaped part, and the density of said second portion differs from the density of the first portion by a predetermined compression factor.

21. The shaped part of claim 1, further comprising a granulated additive selected from the group consisting of cork, rubber and a mixture thereof incorporated in the cellular structure.

22. The shaped part of claim 1, further comprising reinforcement elements incorporated in the cellular structure.

23. A method of producing a three-dimensional shaped plastic foam part, comprising the steps of (a) mixing plastic foam granules having at least one property selected from the group consisting of a predetermined range of sizes and different hardness in a predetermined mixing ratio to obtain a mixture of the plastic foam granules, mixing the mixture of the plastic foam granules with a liquid primary material until the granules are coated with the liquid primary material and a mixture of coated plastic foam granules is obtained, (b) storing the mixture of the coated plastic foam granules in an intermediate storage tank, (c) conveying a preset quantity of the stored coated plastic foam granules from the intermediate storage tank to a mold cavity of a mold closed on all sides, (i) the stored coated plastic foam granules having been weighed to provide a quantity thereof which is between 3% and 15% above the quantity required to fill the mold cavity, and (ii) the weight of the stored coated plastic foam granules having been so controlled that it corresponds exactly to that of the quantity to fill the mold, (d) reducing the volume of the mold cavity at least in partial regions thereof after it has been filled with the mixture of coated plastic foam granules, (e) triggering a reaction of the liquid primary material by applying pressure and heat until a continuous cellular structure of plastic foam has been formed and the plastic foam granules have been interconnected by the cellular structure of plastic foam after the volume of the mold cavity has been reduced at least in partial regions thereof, (f) venting gaseous reaction media from the mold cavity through openings in the sides of the mold, and (g) removing the three-dimensional shaped part from the mold cavity.

24. The method of claim 23, wherein the plastic foam granules are made of recycled plastic foam.

25. The method of claim 23, wherein filling materials are added to the mixture of plastic foam granules.

26. The method of claim 23, wherein the reaction of the liquid primary material is triggered by applying water vapor under pressure to cure the liquid primary material.

27. The method of claim 23, wherein the stored coated plastic foam granules are weighed to hold the quantity thereof to no more than between 5% and 10% of the quantity to fill the mold cavity.

28. The method of claim 23, wherein the weighed quantity of the stored coated plastic foam granules is conveyed to the mold by a conveying gas blowing the weighed quantity into the mold cavity.

29. The method of claim 28, wherein the conveying gas is permitted to be vented through the openings in the sides of the mold.

30. A method of producing a three-dimensional shaped plastic foam part, comprising the steps of (a) reducing plastic foam to granules of a predetermined range of sizes, (b) mixing the plastic foam granules in a predetermined range of sizes in a predetermined mixing ratio to obtain a mixture of the plastic foam granules, (i) the mixture of the plastic foam granules having been weighed to obtain the predetermined mixing ratio, (c) conveying the weighed mixture of the plastic foam granules to a mixing device to mix the granules with a liquid primary material until the granules are coated with the liquid primary material and a mixture of coated plastic foam granules is obtained, (d) supplying a controlled quantity of the coated plastic foam granules to an intermediate storage tank to obtain a preset quantity of the mixture of coated plastic foam granules, (e) conveying the preset quantity of the mixture of coated plastic foam granules to an inlet of a conveying blower and blowing the mixture into a mold cavity of a mold closed on all sides, (f) reducing the volume of the mold cavity at least in partial regions thereof after it has been filled with the mixture of coated plastic foam granules, (g) triggering a reaction of the liquid primary material by applying pressure and heat until a continuous cellular structure of plastic foam has been formed and the plastic foam granules have been interconnected by the cellular structure of plastic foam after the volume of the mold cavity has been reduced at least in partial regions thereof, (h) venting gaseous reaction media from the mold cavity through openings in the sides of the mold, and (i) removing the three-dimensional shaped part from the mold cavity.

31. The method of claim 30, wherein a larger quantity of the mixture of coated plastic foam granules is fed into the partial regions of reduced volume than into the other regions of the mold cavity.

32. The method of claim 30, wherein the mixture of coated plastic foam granules is fed into the mold cavity through the openings by a conveying gas.

33. The method of claim 10, wherein the conveying gas is vapor.

34. A method of producing a three-dimensional shaped plastic foam part comprising the steps of (a) mixing plastic foam granules having at least one property selected from the group consisting of a predetermined range of sizes and different hardness in a predetermined mixing ratio to obtain a mixture of the plastic foam granules, mixing the mixture of the plastic foam granules with a liquid primary material until the granules are coated with the liquid primary material and a mixture of coated plastic foam granules is obtained, (b) feeding a preset quantity of the mixture of coated plastic foam granules into a mold cavity of a mold closed on all sides, (c) introducing reinforcement elements in the mold cavity before the mixture of coated plastic foam granules has been fed into the mold cavity, and positioning the reinforcement elements in the mold cavity by holding parts, (d) reducing the volume of the mold cavity at least in partial regions thereof after it has been filled with the mixture of coated plastic foam granules, (e) triggering a reaction of the liquid primary material by applying pressure and heat until a continuous cellular structure of plastic foam has been formed and the plastic foam granules have been interconnected by the cellular structure of plastic foam after the volume of the mold cavity has been reduced at least in partial regions thereof, (f) removing the holding parts from the mold cavity before the reaction of the liquid primary material has been completed, (g) venting gaseous reaction media from the mold cavity through openings in the sides of the mold, and (h) removing the three-dimensional shaped part from the mold cavity.

35. An installation for producing a three-dimensional shaped plastic foam part from plastic foam granules bonded together by foaming a liquid primary material, comprising (a) a plurality of tanks respectively receiving the plastic foam granules and the liquid primary material, (b) a device for reducing the plastic foam granules to a predetermined size, (c) conduit means connecting the reducing device to respective ones of the tanks receiving the plastic foam granules, (d) a weighing tank having an inlet arranged to receive the plastic foam granules of predetermined size from the reducing device and an outlet, (e) a device for mixing the plastic foam granules of predetermined size with the liquid primary material, (f) further conduit means connecting the mixing device to respective ones of the tanks receiving the liquid primary material and to the outlet of the reducing device, (g) an intermediate storage tank comprising a weighing device and arranged to receive the plastic foam granules mixed with the liquid primary material, (h) a mold having a mold cavity, and (i) a supply line connecting the intermediate storage tank to the mold cavity, the supply line comprising (1) a conveying device having an inlet and (2) a conveying conduit connected to the intermediate storage tank, the conveying conduit being connectable to the conveying device inlet.

36. The installation of claim 35, wherein the reducing device is arranged downstream of the receiving tanks and upstream of the mixing device.

37. The installation of claim 35, further comprising control means for the weighing device of the intermediate storage tank and for the conveying device, the control means controlling the quantity of the plastic foam granules mixed with the liquid primary material to no more than between 5% and 10% above the quantity to be conveyed into the mold cavity, whereby the weighing device monitors the quantity and conveyance of the plastic foam granules mixed with the liquid primary material.

38. The installation of claim 35, wherein the mold has sides defining the mold cavity, the sides having ventilation openings, further comprising a vacuum pump and a source of a reaction medium for the liquid primary material, the ventilation openings being in selective communication with ambient air surrounding the mold, the vacuum pump or the reaction medium source.