WO1991011555A1

WO1991011555A1 - Process for the manufacture of thick-walled shaped articles for use, in particular, for packaging purposes

Info

Publication number: WO1991011555A1
Application number: PCT/DE1991/000067
Authority: WO
Inventors: Hans Viessmann; Thomas Viessmann; Gerhard Schneider
Original assignee: Viessmann Werke Gmbh & Co.
Priority date: 1990-01-24
Filing date: 1991-01-23
Publication date: 1991-08-08
Also published as: EP0504311A1; ATE92125T1; EP0504311B1; ES2044722T3; DE4001918C1; DE59100232D1; DK0504311T3; CA2069295A1

Abstract

In the process described, the raw material, in particular recycled paper and/or waste cardboard, in the form of an aqueous suspension, is brought by a suction filter out of suspension and on to a perforated surface (3) the shape of which corresponds to that of the packaging article (VS). In order to manufacture shaped articles (VS) of this kind with sufficiently thick walls by suction filtering, the process disclosed calls for the suction effect on the raw material in the suspension to be exerted in the suction filter through spaced holes (5) in the suction surface (3) and through a bed (6), consisting of one or more layers, located directly on the suction surface. This bed, which transmits the suction effect, has mesh apertures which are smaller than the holes in the suction surface.

Description

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The invention relates to a method and a suction mold for producing thick-walled shaped pieces, in particular for packaging purposes.

Methods and suction forms for the stated purpose are known, for example according to the Paper Trade Journal, November 13, 2003, pp. 175-180. Such a method and corresponding suction molds can be used to produce moldings which, however, are only relatively thin-walled and therefore relatively soft, ie are to a certain extent unstable. In order to be able to remove them from the suction mold at all with the appropriate thin walls, these fittings require a dewatering and drying treatment immediately following the suction molding. Such known fittings are sufficient, for example in the form of "egg crates" or bowl-like fruit and vegetable bases, despite their thin walls, but they are not suitable for replacing polystyrene fittings that need ¬ are maneuverable to fix heavier objects, for example devices of all kinds or device parts in a packaging carton, although this would be highly desirable from an environmental point of view. For this reason, devices, equipment parts or, for example, wine and champagne bottle containers are still introduced in shape-matched polystyrene moldings and in corresponding cardboard packaging, since only with such moldings can a non-displaceable storage in the cardboard box and, in addition, break-proof shipping or Transport are guaranteed. The replacement of polystyrene fittings with fittings based on fiber material, which is easily and environmentally easily rotten, has hitherto hindered the fact that with such a raw material, as mentioned, only fittings with a small wall thickness could be produced which, on the one hand, could not be used when wet due to a lack of inherent stability can be removed from the suction mold immediately after suction molding, which would be desirable in terms of rational production and, on the other hand, because of its Thin walls for heavier packaged goods cannot offer the necessary security against displacement and breakage within a packaging box. Regarding such fittings, reference is made to US-A-3 016 177 and 3 315 50, which, however, can only be produced from appropriately processed fiber pulp and are thin-walled (maximum up to 3 mm) and which therefore also require a strong rib-like structuring in order to do so to make it sufficiently stiff at all.

The producibility of only thin-walled shaped pieces from raw material based on fibrous material is obviously due to the fact that the suction surface of the suction molds previously used for it clogs up too quickly, so that despite the vacuum remaining on the suction mold, it no longer leads to corresponding further and greater wall thicknesses leading deposits can come, which also form a sufficiently strong bond with the already accumulated, sucked material.

The invention is accordingly based on the object of improving the known method of suction shaping and the suction forms necessary for this in such a way that starting from waste paper and / or cardboard waste in the form of chips, there is sufficient thick-walled material with regard to stability and also as immediate removal as possible from the suction mold Shaped bodies should be able to be produced.

This object is achieved with a method of the type mentioned at the outset according to the invention in that the suspended or suctioned raw material in the suspension of suction on the suction mold through holes in the suction surface spaced apart from one another and at least one suction permeable element arranged directly in front of the suction surface Layer with a mesh size smaller than the hole size is exercised and with regard to the necessary suction shape in that the suction surface is made of a dimensionally stable carrier with holes distributed and spaced apart from one another over the suction surface, and that the carrier has at least one fine-meshed layer on the molding system side. such as mesh, grid or fabric layer is covered, the mesh width of which is kept smaller than the cross section of the holes. Advantageous and practical forms of further training are explained in more detail.

As far as the indication "about" is contained in the subclaims, the reason for this is that the actual limits cannot be determined more or less precisely, especially since it is inevitable that no precise specifications can be made regarding the raw material to be processed, since in the preparatory processing this is subject to a comminution digestion which can never be determined precisely for each individual piece and then also to the dissolution effects during the suspension.

Surprisingly, it has been found in this procedure according to the invention in connection with the specially designed suction mold design that wall thicknesses for fittings of this type can easily be achieved, which correspond at least to twice the wall thickness achievable to date, which means that moldings produced in this way are not only be removed or removed from the suction mold immediately, but these also have the necessary inherent stability even in the dry state in order to be able to serve as a replacement for the polystyrene moldings previously used for this purpose. The decisive factor here is that according to the invention the suction is no longer brought into effect directly as before by a fine-meshed and in this respect only to a limited extent stable suction surface, but by a relatively coarsely perforated support and at least one so-called permeable layer arranged directly in front of it with a smaller mesh size measured from the hole size. The attainable and surprising effect of a larger material suction strength is probably at least partly explained by the fact that cross-currents can apparently form between the perforated support and the fine-meshed, permeable layer, which pull the suction with already deposited raw material Allow it to remain effective for a longer period of time, so that overall thicker material deposits result, which can neither be th carrier can still be achieved with a fine-meshed sieve molding alone. It should also be decisive, however, that the dimensionally stable support permits a higher suction pressure, which leads to a greater material precipitation strength.

At the end of the suction process, the negative pressure is maintained for a certain period of time in order to at least roughly dewater the shaped piece, which, however, due to its wall thickness and despite the residual water content still present, is already inherently stable so that it is already stable can be removed from the suction mold while also maintaining its predetermined shape. In addition, however, the larger wall thickness after drying of the shaped part also ensures that it has sufficient stability or rigidity to be able to serve as a replacement for the polystyrene shaped pieces.

The method according to the invention also has the great advantage, of course, that waste paper and / or cardboard waste only needs to be comminuted but not processed for fiber digestion, i.e. The wastes shredded into chips are simply added to the suspension liquid, softened and then the suspension enriched with chips can be processed directly.

It does not matter if the waste contains very occasional plastic chips, which are often found in paper and cardboard waste. As it turned out, the presence of plastic chips in the finished pieces is even advantageous, since these contribute to the increased strength of the shaped pieces, but more than 57 plastic chips should not be included.

Although the main concern of the method according to the invention is to process the raw material in the form of chips and thus to be able to produce shaped pieces with a sufficiently large wall thickness, it is also possible to dissolve the paper waste before processing into individual fibers and to separate them or, for example to use sanded wood for the suspension. As has been shown, it is also not absolutely necessary to add additional binders to a suspension of chips in the water, since in any case sufficient chip cross-links result during the suction process, which then impart a sufficiently stable internal structure to the respective molded piece in the finished state. In addition, the raw material to be processed also brings with it a certain proportion of binder that has dissolved in the suspension. If binders are still added to the suspension, then such binders are suitable as are customary in paper manufacture, for example rosin saponified with boiling soda solution or sodium hydroxide solution, but also phenolic resins, coumarone resins, montan resins or Resins from cell lye. In addition to resin glues, additives for sizing can also be casein, starch, animal glue, water glass or the like. come into use.

The method according to the invention, the associated suction form and further advantageous and practical embodiments are explained in more detail below on the basis of the graphical illustration of exemplary embodiments.

It shows schematically

1 greatly enlarged a section of the suction surface with a corresponding section of the raw material sucked thereon for the formation of the shaped piece;

2 shows an enlarged section through the suction surface designed according to the invention;

3 shows a plan view of the suction surface from the raw material support side;

Fig. A section through a suction box; 5 shows a section through a suction box in a special embodiment;

Figure 6 seen the view of a fitting from the "raw side".

FIG. 7 shows a section through the molding according to FIG. 6 in connection with an object to be packaged;

8, 9 in section special embodiments of the suction surface;

Fig. 10 in perspective and cut the example of a fitting and

11 shows a flow diagram of the method.

As can be seen from FIG. 4, the suction mold consists of a suction box 1 with a vacuum or vacuum connection 2 and a suction surface 3 adapted to the desired shape of the shaped piece VS. As far as is shown in FIG. 4, the suction box 1 is provided with a cover 9, this has a correspondingly large inflow connection 10 for the suspension, through which the suspension flows when the entire molding box 1 is exchanged for the suspension in the mold cavity. In order to be able to produce shaped pieces VS with a wall thickness S of at least up to 6 mm with such a suction mold, the suction surface 3 according to FIG. 1 is designed in a special way, namely in such a way that the suction surface 3 consists of a dimensionally stable support 4 Holes 5 distributed over the suction surface and spaced apart from one another (see also FIG. 3), the carrier 4 on the side on which the shaped piece VS is to be formed having at least one fine-meshed layer 6 such as mesh, grid or Fabric layer (for example made of nylon) is covered, the mesh size of which is kept considerably smaller than the cross section of the holes 5. The holes 5 have a diameter D of 1 to 2 mm, preferably 1.5 mm and a distance A from one another 4 to 6 mm, preferred 5 mm. Preferably, copper wire mesh is used for the layer 6, which has a wire thickness of 0.2 to 0.4 mm, the wires 7 in the fabric being at a distance Aj of 0.3 to 0.5 mm from one another. It has proven to be particularly advantageous and effective that the crossing wires 7 of the single-mesh layer 6 extend in two planes E, as illustrated in FIG. 2. The enlarged representation according to FIG. 2 shows and, as indicated by arrows, that there are to a certain extent cross currents in the layer 6, which are obviously also decisive for the fact that the raw material in the suspension is in the desired large layer thickness on the layer 6 can settle, which was previously not possible if only a sieve-like, relatively thin and only limited vacuum suction surface was used, which clogged accordingly quickly and thus set the layer thickness too early. Of course, several very thin layers 6 can also be arranged one above the other, each of which has a maximum thickness of only about 1 mm. This layer 6 must therefore not be a correspondingly thin and only perforated sheet, since no transverse flow can arise on such a sheet. In the case of a multilayer configuration of the layer 6 (see FIG. 8), the mesh size of the individual layers may well be the same or approximately the same as the size of the holes 5, since this results in a staggering of the passages in the depth. Depending on the choice of material for the layers 6, one or more layers 6 can also take over the function of the carrier 4, ie replace it, the layer 6 'on the suction side imparting its fine surface structure to the molded part. With such a design it is of course a prerequisite that the material for the layers 6 is a dimensionally stable material, ie it must not be a soft textile fabric, for example.

The material to be used for the formation of the layer 6 can be both dimensionally stable and, preferably, dimensionally stable material, in the latter case there being the possibility, for example, of the layer 6 by pressing in corresponding tools of the shape of the Adjust carrier 4 and to fix them on the carrier 4 in a suitable manner. The top view (in the direction of arrow P according to FIG. 2) in FIG. 3 corresponds to the dimensions of an actual embodiment, in which the holes 5 have a hole size of approximately 1 mm in diameter, the layer 6 being two to four times larger has a smaller mesh size, and furthermore flat F and strip-shaped wastes SA, as shown, are contained in the supplied suspension. Flat waste, i.e. chips, has sizes of about 1 to 6 cm2, with which the best results could be achieved. Stiff-shaped, that is to say acid-herb-like waste SA, such as is obtained when comminuting, for example, document papers, has dimensions of about 1 to

5 mm wide and approx. 10 to 30 cm long.

The suction surfaces 3 in the mold boxes 1 according to FIGS. 4, 5 are shown there in the simplest form. Different and much more complicated shapes of the carrier 4 and the associated position

6 are, however, readily possible, it being only necessary to ensure that there are no areas in which the suction-effective areas shield one another, which would prevent the precipitation or suction of raw material particles.

In particular with regard to more complicated shapes of the shaped pieces and the associated, difficult formability of the shaped piece produced, but also with simple shaped areas, as shown, there is an advantageous embodiment of the suction mold F in that it is at least in two parts and thus the molded parts Fi and F ₂ to be movable apart. In the case of a simple molding box 1, as shown in FIG. 4, a suitable joint 14 is sufficient for being able to swing open the upper mold parts 9. However, it is also possible, in particular for complicated molded boxes according to FIG. 5, to provide lifting guides 15, with the aid of which the upper part can be raised. As has been shown, due to its larger wall thickness, the shaped piece which is formed is in a position to withstand the loads which occur when the shape is divided, ie not to tear. With the greater wall thickness that can be achieved, there is also the advantage of being able to be shaped using divisible shapes. In the shapes shown in FIGS. 4, 5, the covers 9 result in clean edges on the shaped pieces.

The special feature of the design of the suction form F according to FIG. 5 is that in the form F there is at least one further suction surface 3 'with a separate suction box 1' on the suction side, this suction box 1 'having a separate suction nozzle 1 " The further suction surface 3 'is assigned with its area 8 close to the other suction surface 3 at a distance Di which corresponds to a maximum of approximately twice the wall thickness S of the molded part VS to be produced. to provide the shaped piece VS with stiffening web formations 11, which contribute significantly to the further stability of the shaped piece VS, in particular as far as the more or less large edge regions 12 of the shaped piece are concerned. For this purpose, reference is made, for example, to FIGS. 6 shows a view of a molded part VS produced from the non-smooth side, and FIG. 7 shows a section through such a molded part, wherein, as can also be seen from FIG. 7, two such shaped pieces serve to fix an object G to be packaged in a cardboard box K. The web cavities 13, as indicated in FIG. 6, result from the suction surfaces 3 ′ additionally arranged in the form F according to FIG. 5.

As far as the spacing of the holes 5 in the carrier 4 from one another is concerned, it is important to note in this regard that on the one hand a sufficiently large suction cross section is created on the one hand and on the other hand the carrier 4 is sufficiently stable to withstand high vacuum (e.g. 120 mb) not related to deform its given shape. The spacing values are also fluid here, since they depend on the hole size, the carrier material, the wall thickness of the carrier and ultimately also on the material of the fine-mesh layer 6 applied directly to the carrier 4. So far, too the hole spacing (for example corresponding to the diameter of the holes 5) is also a factor to be considered for the wall thickness of the shaped pieces to be achieved.

11 shows the flow diagram of the entire process. The paper waste 16 is brought to the desired shredder size in a suitable shredding machine 17 and conveyed into the mixing tank 18, to which a sufficient quantity of suspension liquid is fed from a tank 19. This liquid with the contained therein and on softened wafers then passes into the actual work basin 20, into which the molded boxes 1 are immersed with a suitable lifting mechanism 21, these molded boxes 1 via a vacuum line 22 and a pressure-tightly closed separation container 23 with a vacuum pump 24 are connected on the suction side. The aspirated liquid is returned from the container 23 to the tank 19 by a pump 25 and from there takes part in the cycle again. As indicated by dashed lines, all tanks and containers are provided in duplicate and are accordingly integrated into the system accordingly. This double arrangement serves, in particular, to have sufficient time in the mixing containers 18 for continuous production to soften the batch of chips entered in each case.

Design example:

For this purpose, reference is also made to FIG. 11. The chips produced from the paper waste 16 with the comminuting machine 17 have a shape that cannot be defined geometrically, but a cut size of the order of 1 to 6 cm 2. Approx. 500 liters of liquid with a quantity of chips of 3 to 5 kg are prepared and mixed in the mixing container. The liquid temperature corresponds to the normal ambient or line temperature, but can be increased if this should require the peculiarity of the chips. With a finished weight of the molded part to be produced in the dry state of approx. 200 g, which corresponds to a mold box size of approx. 400x400x150 mm3, the suction process takes place with an applied suction pressure of approx. 120 b on the molding box 1 and with a wall thickness of the molding to be produced of 5 to 6 mm only about 3 to 5 seconds. The residual moisture in the molding produced depends on how long the suction pressure remains on the molding box 1 when it is is lifted out of the suspension in the working pool 20 by means of the lifting mechanism 21. After removal from the molding box 1, the molding or the molding is dried in a dryer 26.

Claims

Claims:

1. Process for the production of thick-walled moldings, in particular for packaging purposes, in particular from waste paper and / or cardboard waste, the raw material contained in a water suspension being sucked up from the suspension by means of a suction molding tool onto the suction surface corresponding to the shape of the packaging molding , characterized in that on the bloated and to be sucked raw material in the suspension of suction on the suction mold through spaced holes of the suction surface and through one or more layers, arranged directly in front of the suction surface, so-permeable layer with smaller than the hole size dimensioned mesh size is exercised.

2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that waste paper and / or cardboard chips are used as the raw material in the suspension.

3. The method according to claim 1 or 2, characterized in that the suction through holes with a diameter size of 0.5 to 3 mm, preferably 1 to 2 mm and through the arranged suction-permeable layer with a smaller than the hole cross-section corresponding mesh size to effect is brought.

4. The method according to any one of claims 1 to 3, characterized in that when using raw material in the form of strip-shaped chips, those with a width of 1 to 5 mm and a length of 1 to 30 cm and / or use of non-striped chips those with an area size of the order of 1 to 6 cm. A method according to claim 1 or 2, characterized in that when raw material which has dissolved up to fibers is also used, additional binder is added to the suspension.

Suction mold for carrying out the method according to claim 1, consisting of a suction box (1) with vacuum connection (2) and with a suction surface (3) corresponding to the desired shape of the packaging molding (VS), characterized in that the suction surface (3) consists of a dimensionally stable carrier (4) is provided with holes (5) distributed and spaced apart from one another over the suction surface and that the support (4) is covered on the molding piece side with at least one fine-meshed layer (6), such as a mesh, grid or fabric layer, the mesh of which is kept smaller than the cross section of the holes (5).

Suction form according to claim 6, so that the crossing strands (7) of the at least one fine-meshed layer extend in two planes (E).

Suction form according to claim 7, so that the at least one layer (6) is dimensionally stable and is pre-shaped to match the shape of the carrier (4).

Suction form according to claim 6, d a d u r c h g e k e n n z e i c h n e t that the holes (5) of the carrier (4) a diameter (D) of

0.5 to 3 mm, preferably 1 to 2 mm and the distance

(A) two holes (5) to each other 2 to 8 mm, preferably

Is 5 mm. 10. suction mold according to claim 6, characterized in that the shape (F) at least in two parts and the molded parts

(Fi, F ₂ ) are designed to be movable apart.

11. Suction form according to claim 6, characterized in that in the form (F) on the suction side at least one further suction surface (3 ') with a separate suction box (1') is arranged, with its the other suction surface (3) close area (8) in a distance (Di) is assigned, which corresponds to a maximum of twice the wall thickness (S) of the packaging molding (VS) to be produced.