DE4140875A1 - Recyclable fibre packs for foodstuffs - produced by hot surfacing electrostatically charged porous preformed holders with thin thermoplastic or elastomer film, under vacuum - Google Patents

Abstract

A seal for thermoplastic and/or elastomer coatings is used on containers made of papier mache, cardboard or other natural or modified natural fibres, where the containers concerned are moulded (e.g. by the old process of picking up on a wire from a tank of fibres, as with paper mache) and are so porous that under a vacuum, air passes through them. The holders for the sealant and for the preforming mould transmit vacuum to the surface of the preformed container, moreover the wall of the container has a number of surface holes. A plastic film is applied to its surface by vacuum acting through the wall thickness. Pressure tools are heated and electrostatically charged to ensure that the correspondingly heated and charged film lies free from creases on the container, the seal is prevented from clinging to the film by dusting with release agent, pref. wheat flour. ADVANTAGE - The prod. produces fast food containers which can be recycled. They decompose without damage to the environment or evolving harmful gases when incinerated. They pref. use waste paper, can hold liquids, are stable and thermally insulating and are inexpensive.

Description

Technical field

The invention relates to surface smoothing after application of plastic granulate, plastic powder and / or plastic film the surface of a preformed, preferably porous container made of recyclable and easily rotatable natural material or modified Natural material like cardboard / paper mache, the surface of which is sealed, so that liquid and semi-liquid foods are stored in the container and can be kept fresh or warm and this with sufficient stability of the container.

State of the art

For fast food chains, containers are made of thick-walled, foamed Plastic is produced, but it is not recyclable and it cannot rot are.

The legal obligation to take back does not result in such Recyclable packaging difficult to solve problems, their solution are associated with high costs.

Since landfill space has become very expensive today, new ways have to be found be gone to avoid garbage.

Presentation of the invention

The surface smoother (s) smooth and / or structure and preferably calibrate in one or more process steps Pass / Runs - the plastic surface of the preformed and of the workpiece (s) to be machined in such a way that preferably species-specific filler / filler for smoothing / structuring and / or calibration process, part of the release agent, into the workpiece coating surface, which is still partially fluid, is incorporated. This process is with a filling with still missing coating material, or one or more components comparable, which largely deforms the workpiece surface by an unwanted build-up of tension in the same what is avoided in a smoothing process that is due to pushing away Particle based, is not possible - apart from that too the coating material not only coated on it by adhesion Workpiece, but would also attach to the straightener if the filler interface would not prevent this.  

The plastic film which is very thin, and / or the plastic powder is heated by the heaters Fig. 2 (22), Fig. 3 (22), Fig. 5 (22/29), (2) and with a negative overpressure sucked through the porous body of the preformed container passes through the vacuum lines (6) in Fig. 1, Fig. 3, Fig. 5 and Fig. 6. Next are the devices ( 29 ' ), ( 29 ), ( 52 ) for the electrostatic charging of pressure bodies ( 11 ), ( 11' ), the container (workpiece) ( 1 ) and the plastic powder and / or Plastic film. In the method of smoothing shown in FIGS . (1), (2), (3), (5) and (6), the premixed components are preferably metered by determining the mass of the same on the basis of instructions drawn up and issued by the manufacturer , such as tables, in which the other important parameters for the process such as the degree of static charge of the pressure body, workpiece and release agent and also their type and temperature, as well as, for example, the peripheral speed / number of oscillations / amplitude / type of oscillation / mode of oscillation Pressure body / the pressure body and the feed speed of the workpiece to be coated / coated / the workpieces to be coated / coated are specified.

For the surface sheets with torque setting / torque control is about the surface pressure body rolling torque opposite the rolling torque a favorable rubbing between the pressure body for the process and workpiece / coating layer surface set / controlled, since the degree of friction during the machining of the workpiece the electrostatic charging of the same and the pressing body (s) and thus influences / determines the release agent layer thickness on the same. For the surface sheets with a supply line / supply lines for Electronic charging can be done in a novel way, in addition via the torque control and thus regulation of the static charge of the pressure body, Release agent and workpiece, from the beginning of the process steps, the charging potential of pressure body, release agent, coating and Workpiece on one of the manufacturer of the coating material (s) and / or devices for smoothing, structuring / calibration and for example size specified in tables and set by a Control loop are kept. Also in a new way is in her electrostatic potential and temperature controlled mechanical Scraper with attached suction devices  Release agent layer thickness on pressing body / s and workpiece / s according to regulated values and the requirements for the coating / Coating steps automatically kept constant.

This is an essential prerequisite for process optimization. When applying a plastic, modified natural material, natural material, metal, ceramic, substrate layer / layering or combinations thereof on workpieces made of metal / s, ceramic, substrate layer / s, plastic / s, natural materials, modified natural material / modified Natural substances and or combinations of the aforementioned substances and preferably subsequent smoothing and / or structuring and preferably calibrating the entire workpiece thickness as a further novel method possibility, characterized in that according to claim 1 the adherence / sticking of the z. T. still partially liquid coating of the workpiece (s) on the pressing body (s), workpiece transport device (s), release agent scraper device (s) by covering with film or powder ( 18 ) in the handle ( 16 ), completed by cover ( 17 ), and by which adjustable dosing device ( 12 ), which is rotatable about the part ( 14 ) and loosely held by a striking device ( 13 ), is given up on the roller-shaped pressing body ( 11 ), ( 11 '), the rolling resistance of which is continuously changed by the setting ( 19 ) can be.

The part ( 19 ) is the heating and charging element (for static charging) with the supply line ( 22 ) in the handle ( 16 ') for the separating powder, which via the line ( 5' ), preferably with compressed air as the carrier medium, optionally supplied can and the pressing body ( 11 ), ( 11 ' ) on the baffle ( 15 '), which is attached to the bracket ( 15 ) for the pressing body, reached.

Fig. (5) and Fig. (6) show the devices for assignment of the container surface with plastic film and subsequent cutting and fining / calibration or texturing operation.

The preformed workpieces from porous Pappmach' / box (1) are between the heads (53/3) and the brought pressure-applying body / receptacle (11) in an automatic Zuführgang and there with film (7 '), which over the heating and charging means (2) was prepared, also automatically filled and applied by the suction air from line (6) and the static charge of the vessel, to the surface of the preformed container and smoothed by the pressing of the oscillating head (53/3). Powder (7) of part (16) via the worm (4) the heating element (8) is fed with its leads (22/29), prevents adhesion of the smoothing head and the recording, at the semi-liquid by heating the film.

An embodiment of the Oberflächenglätters for installation in handling device (industrial robot), FIG. (1) and Fig. (3).

These versions are particularly suitable for small quantities.

Surface smoothers with a preferably paraboloidal pressure body for application, or for smoothing and / or calibrating and also for structuring an applied and semi-liquid / still soft plastic, modified natural material, natural material, sintered metal powder, ceramic, substrate and combination material layer on workpieces from preferably Metal, plastic, ceramic and natural materials and modified natural material, characterized in that according to claim 1, the pressing body ( 61 ) running around the longitudinal axis of the handle ( 16 ′), the rolling resistance of which is infinitely adjustable by means of a device, and the friction force between the pressing body and workpiece, reduced or increased, by the torque possibly generated by its motor drive, which adjusts itself automatically to the correct friction torque when driven by the conveying medium for the powder, which is used as a release agent. This self-activity is necessary when using the surface smoothing device in handling devices, since control units on the smoothing device usually have to be dispensed with due to space restrictions.

In a further embodiment, the pressing body is continuously adjustable in its position relative to the handle, at an angle different from 0 degrees to the handle ( 16 ').

The version suitable for mass production is according to ( Fig. 5, 6) of a surface smoothing device, characterized in that according to claim 1, a coating layer (s) made of plastic, modified plastic, natural material, modified natural material (s) applied to a workpiece / on workpieces, Metal powder with binder, ceramic powder with binder, substrate and mixtures of the aforementioned materials in a still partially liquid state by using a release agent - preferably wheat flour - for coating the pressing body against sticking - the film / s is smoothed and / or calibrated, but is also optionally structured / by the coated workpieces / the coated container / workpiece under the rotating, preferably by friction / frictional forces and / or by motor drive swinging, staggering, oscillating, reversing in addition and the rotary movement superimposing or exclusively moving / moving pressure body (s) to be led through. This passage of the workpieces / the workpiece preferably takes place once under one or more such pressure bodies. The workpiece is supported by counter-rollers, link conveyor belts, conveyor belts and other suitable devices, which can then also be used as pressure bodies and are then also coated with release agents to prevent coating material from sticking, preferably by applying an adhesive force due to electrostatic charging by charging devices, as in the case of the opposite ones Pressing bodies used. This results in an electrostatic field on the pressing bodies on one side or on multiple sides with respect to the workpiece (s) to be machined, which is weakened or strengthened by the friction between the pressing bodies and the coating of the workpiece / the workpieces depending on the polarization. This is preferably used to automatically adjust the strength of the charge to the process sequence in a control loop. In order to be able to maintain narrow tolerance ranges during smoothing and or calibration and, if necessary, structuring - the oscillating, oscillating, linearly moving pressing body is dressed with an electrostatically charged, preferably oscillating, electrostatic "ruler", in that charged separating agent particles from the separating agent jacket of the pressing body are made by corresponding potential changes on charged release agent particles are "broken out". In order to generate an idea of the delicacy of this electronic dressing, it should be pointed out that the grain sizes of the release agent can be in the resolving power of a good workshop microscope. With appropriate storage of the pressure body and compensation of the shape deviation of the receiving frame and the actual pressure body by electronically measured deviations from a predetermined value and automatic electronic control of the layer thickness of the release agent, the requirements in fast food production can be easily met and thus the committee drastically be reduced.

This way of maintaining a given shape within narrow limits of the Tolerated shape deviation is new and very economical and safe. This method can also be used to create very sharply contoured depressions and increases in workpieces can be achieved, which was previously not possible was, namely, that incorporated contours filled with release agent  be filled and then rolled over again, or the still to be smoothed and or calibrated or also to be structured remaining surface with preferably roller-shaped pressing bodies Finished in the partially liquid state of the workpiece coating becomes. Then the release agent is sucked off / blown away / dumped / pulled away by electrostatic fields and after a reprocessing fed to the release agent container (s).

The release agent striking the workpiece is dosed first by screw conveyors, which are driven by a variable drive are driven. Excessive release agent is sucked off through hoods and fed to the release agent container (s) again. By a Heating and charging unit, which is installed around the screw conveyor the parameters of temperature and electrostatic charge at Release agents correspond to the manufacturer's instructions.

Also the device / apparatus / machine will be prepared for the coating process in a new way, by the pressing body - preferably Rollers - be turned on their circumference and after a coating with a on the material of the workpiece to be coated and of the coating material provided for this purpose provided, for example with a dressing diamond. According to the invention, the coating material must be heatable according to claim 1 and be statically chargeable and this by the preferably in heating and charging devices located on the rollers.

This type of preformed container, which is used for packaging fast food, is covered with a moisture-resistant layer of very thin plastic and can also be easily calibrated due to the automation of subsequent production processes. In the patent application PCT / DE 00891 / WO 91/08057, smoothers are mentioned in which powdered release agent is used to prevent coating material from adhering to the smoothing bodies, but no plastic film is used for coating here; furthermore, the coating material is not applied to the surface of the part to be coated - here a packaging container for fast food - by suction air, which acts on the coating material through the porous preformed paper mache / cardboard body. According to the invention, the coating, smoothing and calibrating of an automatic cup made of paper mache is shown as an example in FIG. 4 in the stations labeled I to V. The conveyor unit ( 10 ) rotates intermittently.

FIGS. 5 and 6 show the coating of a Warming / transport container for fast food.

Claims (3)

1. Surface smoothers for plastic coating with thermoplastics and / or elastomers for containers made of paper mache, cardboard or any other type of fibrous natural materials and / or modified natural materials, which after preforming - for example by scooping according to the old papermaker type from a trough with fiber mass suspended in it - Are so porous that a negative overpressure can be passed through them over a large area, characterized in that the receptacles of the surface smoothers ( 11 ), and the shape which otherwise surrounds the preformed container (s) conduct the negative overpressure to the surface of the preformed container and are designed in such a way that a sufficient negative overpressure builds up in the wall layer thereof, in that a large number of bores open out on the surface of the preformed container. Furthermore, the smoothing and calibration process is designed in such a way that a plastic film is applied to the surface of the container preformed for this process with the appropriate porosity by a negative negative pressure generated in the wall thereof.
In the process, the pressing body ( 11 ), ( 11 ') are heated and electrostatically charged so that a crease-free application of the film, which is also heated and charged, is possible on the surface of the preformed container.
Dusting with a separating agent, preferably wheat flour, prevents the smooth body from adhering to the film. 2. Surface smoothers for plastic coating with thermoplastic and / or elastomers for containers made of paper mache, cardboard or any other type of fibrous natural materials and / or modified natural materials, which after preforming and subsequent drying are coated with powdered and / or granular plastic according to claim 1 characterized in that the material applied and attached to the wall of the preformed container is smoothed by, after melting and dusting with powder, to prevent it from adhering to the straightener with the programmed sequence and the required parameters for temperature, pressure, Speed, rolling moment u. Is smoothed motion provided novel control of the smoothers (of Fig. 1, Fig. 2, Fig. 3, Fig. 5 and Fig. 6) and calibrated. 3. Production of porous preformed bodies from recyclable and / rotten fibrous natural substance and / or modified natural substance, suitable for coating with food-safe plastic, the is preferably colored or printed on one side.