DE2236581A1 - METHOD FOR MANUFACTURING OBJECTS FROM SEVERAL CONNECTED LAYERS OF MATERIAL, IN PARTICULAR PLASTIC LAYERS - Google Patents

Description

Patent attorneys

Dr. O. Loesenbeck Dipl.-ing. Stracke

Dipl.-Ing. Loesenbeck Bielefeld, Hei forder Sfiajje 17

15 / Str.

Pressing and punching plant Paul Craemer KG., 4836 Herzebrock / Westf.

Process for the production of objects from several interconnected layers of material, in particular plastic layers

The present invention relates to a method of manufacture of objects made of several interconnected layers of material, in particular plastic layers. Often a very large number of requirements are placed on a material, which it and its inherent requirements Properties cannot meet all. To still have a material with the totality of the gevnschten To have properties, one can create composite materials in which materials with different layers Properties are connected with each other .. You know the different layers of material by gluing connect with each other, nowadays mainly solvent adhesives, multi-component adhesives or hot melt adhesives be used. Thermoplastic materials can

BATH 309386/1032

can also be connected to one another by welding or fusing.

It has now been found that when permanent connections are to be made and the connection the strength of the weakest of the materials involved should have the aforementioned connection technology with different Polymer fails. Resist excessive and firm connection with materials of any other kind In particular, the polyolefins such as polyethylene and polyamide as well as Teflon. Own all of these substances a pronounced separating effect. What is particularly troublesome with such connections is that the different expansion coefficients the materials involved work continuously in the event of temperature changes in the connection area cause, which quickly leads to a breakdown of the connection.

The present invention is based on the object of creating a method with which objects are composed of several interconnected layers of material and thus overall can be produced with the desired properties even if so difficult with other substances Firmly connectable materials such as polyolefins, Teflon and the like are involved. The inventive Solution consists essentially in that a first material layer with a second, at least similar material layer is firmly fused, the second layer of material at least on the still free side to solidify in a porous-cellular manner and open-pored on the free surface held or made and a third layer of material made sufficiently flowable, is poured into the accessible pores of the border zone area, and in them to Solidification is brought about.

309886/1032

The ways shown can be used economically incompatible materials are extremely durable and connect firmly to each other. Because of the known properties, the polyolefins are suitable, for example Polyethylene for many uses. However, there is insufficient rigidity for mechanical loads, so that you can, for example, like a polyethylene with a glass fiber reinforced synthetic resin, for example a Polyester resin, would combine. Such a thing is now easily made possible. It has proven to be very useful proved to make the second material layer consist of the same material as the first layer, however mixed with a propellant that ensures a porous-cellular solidification.

The connection of the first layer of material to the second When it comes to similar or even the same materials, the material layer offers no difficulty at all. The resulting connection is firm and permanent. Due to the open pores on the free surface of the second layer of material and the cellular structure In the limit area it is guaranteed that with a corresponding viscosity of the third material in the processing state this material in a relatively deep border zone area can penetrate into the pores and cells, which also have openings and connections to one another. Goes one, for example, from the image of bursting bubbles the end. result for the cavities in the border zone area. Spherical shapes. Liquid penetrates through an opening here a, which then solidifies to a solid mass, results in an extremely secure and firm association through the existing Clasps of the cast material through the cell walls in the form of real undercuts. The cell walls thus form a permanent connection in the form of a Network.

BATH 309886/1032

It must be taken into account that the volume of the poured Resin is different in the viscous and in the hardened aggregate state. The resin stretches to the Heaction sussmmen. This creates between the cell wall and resin a very small margin. However, since the anchoring goes over the entire common area and also continues into the depths of the border zone area, there is this tiny play in the very small individual connection completely insignificant for the strength of the anchoring and also has the advantage that it is in connection with the preferably at least certain elasticity of the second, The material used as an adhesion promoter layer the work against each other intercept the layers of material perfectly in the event of temperature fluctuations without destruction occur at the anchorage.

It goes without saying that in addition to polyethylene, other thermoplastics such as polyamides, polyvinyl chlorides, propylenes, Polystyrenes, terpolymers, polypropylenes and others are provided with an adhesion promoter layer by this process can be, with which then the third material layer with can be anchored to the other desired properties

Preferred implementation examples of the method according to the invention are explained in more detail below:

Example I.

Moldings, in particular containers, whose inner wall should be produced with the method according to the invention consists of polyethylene, which is approved for the storage of food, has good heat resistance and a high Has chemical properties. With justifiable economic. Wall thicknesses of such polyethylene containers do not have sufficient stability and mechanical strength

WAVY BATH ORIQfNAL

309886/1032

Strength. This is to be achieved through the connection with a glass fiber reinforced synthetic resin compound. A novel configuration of what is known per se has proven to be very useful for the production of such containers Eotation sintering process proven. Under sintering one understands a slow melting of thermoplastic plastic powder on a hot mold surface, that as long as is carried out until the shape of the surface is faithfully reproduced and the desired wall thickness has been reached. With the rotation sintering that has been common up to now, with the d & s plastic powder by rotating spinning on the heated mold. ■ walls and melts there always form bodies, which have exactly the contours of the inner wall of the mold on the outside, while the inside of the molded body is imprecise in the free space, the ■ inside of the form forms after further layers of plastic powder have melted.

In the case of molded bodies, but in particular containers, however, it is often important that the insides are exactly true to shape are in accordance with the shape, while such dimensional accuracy is not required for the outsides. The inventive embodiment now consists in that the first material layer in question here through

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Rotational sintering of the material powder • 'a sinter mold core is formed. The core is expediently heated with oil or the like, while the outer mold is cooled with air or water for continuous operation. Vi; j> d the plastic powder is poured into the mold, this can then be set in axial and possibly biaxial rotation, either at the same or intermittent speed, which once allows the centrifugal force to act on the plastic powder and then the plastic * / ^ r drops or whirls up again, and is also influenced accordingly by gravity, so that it sprinkles the mold core on all sides. Because this with a temperature that is about 'the melting point of the plastic powder

BATH ORIGINAL 309886/1032

if it is heated, the plastic powder melts in layers until all of the powder is used up. The molded body obtained in this way has the exact internal shape desired. In this way, for example, the first layer of material of a polyethylene container can be produced from a polyethylene with the oxy index 6 to 8 MPI and a density of 0.9 ^ 8 gr./cnr 'and ground with a? R 1 & CCIX196X. Grit of SKfirx 100 - 800 U »ι

The adhesion promoter layer has now proven to be very useful in such a case also to be applied to the first material layer by erosion sintering. in the Example is therefore exactly the same as polyethylene above but mixed with 3% propellant second Charge introduced into the sintering mold and this second material layer is then sintered in the same way. It goes with an inextricable melting connection the first compact layer of material. The layer became open-celled by the propellant with a density of 0.380 g / cm. The sintering process, i.e. the supply of heat was finished in such a way that the last layer does not melt smoothly but remains slightly grainy. So becamec a 5 cell-porous outer layer with open cells Cells created on the surface that is still free. Ea has It turned out that even if the zoit for the termination of the heat supply is not completely adhered to is so that the surface begins to melt, so the pores are closed, in a very simple way W: ise the open pores by light rubbing or sanding the surface could be restored. The profitability of the Production method, as in a production cycle with two batches and in one heat the two layers of material in question are formed and bonded together could verden.

BATH ORIGINAL 309886/1032

It is advisable to rub the sintered mold core with a release agent before sintering in order to be able to pull off ^{the formed body + xaDC * ± DCr better.} It is also possible to install an ejector or to press the body off with air.

Finally, a fiberglass-reinforced synthetic resin such as polyester is made sufficiently viscous and cast with the open-pored surface of the second material layer, which is sufficiently viscous Synthetic resin penetrates into the accessible pores of the boundary zone area of the second material layer, solidifies here and is thus firmly anchored to this layer.

Example II

In the previous example the hotation sintering of a container was described. In the case of larger quantities, however, it is more economical to manufacture the polyethylene or polyamide container by injection molding. It has now proven to be very economical and expedient for such containers, generally produced by injection molding processes, as well as for other, in particular, flat objects made of thermoplastic plastics, to fuse the second, porous-cell solidifying material layer into MMes and with the first material layer by means of a powder-flaming syringe2L »A polyethylene is used, corresponding to the first layer of material, which is mixed with a 3% propellant. The flame of a flame spray gun is then passed tightly over the polyethylene surface of the container wall so that it melts. At the same time, the polyethylene powder, mixed with propellant, is blown through the flame to produce the second material layer. When passing through the flame, the ⁺ melt after cooling

BATH ORIGINAL. ": V 3 0 9886/1032

Polyethylene granules and go into the plastic state. If they are in this physical state on the If the surface of the polyethylene container is melted, they immediately form an inseparable fusion bond. The propellant powder granules that have flowed into the melted polyethylene granules have not yet split off the gas. The time it took to pass through the flame was enough to melt the polyethylene grain, but it did not to transfer the heat to the propellant. The process is sluggish. It starts with a delay if that melted grain is already firmly seated on the container wall. The grain then puffs up and the bubble bursts, like that that the porous-cellular structure, which is open-pored on the outside in layers, is achieved. The job can be repeated until the adhesion promoter bar is the desired thickness is reached.

A final layer of material can now be applied as in Example I. made of fiberglass-reinforced synthetic resin.

In this way, panels, semi-finished products and the like can also be produced, which are then cut to size accordingly. Lake anchoring of the fiberglass-reinforced synthetic resin compound can also be done after cutting. Larger structures can also be placed on the plates »ma« - ing »»

Example III ** ft verdem.

It has been found that with the externally open-pored adhesion promoter layer as the second material layer also such material layers can be anchored that completely rom the previous one, if these material layers can only be sufficiently liquefied and then solidified again. So, for example an excellent and in the boundary layer of sufficiently elestisehe anchoring of cement as

309886/1032 ORIGINAL BATHROOM

proved possible. There are, for example, panels made of polyethylene with a polyethylene bonding agent layer produced as a second layer of material according to Example II. These panels are then grouted with cement. Leave it thus produce prefabricated elements that largely can be prefabricated in the factory and their assembly and, if necessary, pouring with concrete, the Prefabricated elements, then the form or formwork for the Form concrete, can be carried out very easily and quickly on the construction site.

If you make the porous-cell adhesion promoter layer, so the second material layer, correspondingly strong, result exceptionally good insulation properties for such prefabricated components both against heat as well as in terms of sound absorption.

Example IV

As another application example, the production was highlighted by pallets. Such pallets are often made of polyethylene. A pallet made of polyethylene is, however, so smooth and slippery on its surface that stacked goods slip off when they are slightly inclined or when the transporter is jolted, unless special lashing or the like is used. So there is the problem of creating pallets whose surface is non-slip. According to one of the implementation examples described above, a pallet body can be formed, for example by spraying, and an externally open-cell adhesion promoter layer can be applied after powder flame spraying. With this applied open-cell adhesion promoter layer, a material can then be cast that either

BATH

303886/1032

even a correspondingly high coefficient of friction possesses, such as a rubber dispersion, or that a corresponding slip resistance is guaranteed by fillers, think of fine-grain minerals, chalk, slate powder, wood shavings and the like as fillers is. It is understood that with the inventive method the pallets also in the highly stressed areas by applying, for example, a glass fiber reinforced Polyester resin as the third layer of material stiffened can.

When anchoring a third layer of material with a high proportion of fillers, the viscosity can result the high filler content so low that a sufficient deep penetration into the border zone area of the open cells of the adhesion promoter layer is no longer given is. In such a case it can be useful to first add a layer with little or no filler to apply and then wet on wet to combine the highly filled mixture with it.

BATH ORIGINAL 309886/1032

Claims (1)

Claims Λ * A method for the production of objects from several interconnected material layers, 'in particular plastic layers, characterized in that a first material layer is firmly fused with a second, at least similar material layer, the second material layer is porous-cellular at least towards the free side Is brought to solidify and kept or made open-pored on the free surface and a third material layer is made sufficiently flowable, introduced into the accessible pores of the boundary zone area and made to solidify in them. 2. The method according to claim 1, characterized in that the first material layer is formed from a polyolefin will. - 3. The method according to claim 1 or 2, characterized in that that the second layer is formed from the same material as the first layer, but mixed with a blowing agent will. 4. The method according to one or more of the preceding claims, characterized in that the second material is layered in the accessible pores of the boundary zone area a glass fiber reinforced synthetic resin is introduced. 5- The method according to claim 1, characterized in that the second porous-cellular material layer is formed by sintering and fused to the first layer of material. BATH 30 9 8 86/1032 G. The method according to claim 1, for the production of Fore bodies, in particular containers, characterized in that the first matorial layer is formed by rotational sintering of the material powder on a sintered mold core. 7. Process according to Claims 5 and 6, characterized in that that immediately following the rotational sintering the first material layer on top of this the second material layer is sintered on. 8. Ancestors according to claim 1, characterized in that the second, porous-cellular material layer by powder flame spraying formed and with the first meterial sight is merged. 9. The method according to claim 1, in particular for the production of Pertigbaueleraenten, characterized in that in the accessible pores of the boundary zone of the outer Haterial layer as a third material layer cement is poured. 10. The method according to claim 1, in particular for the production of pallets, characterized in that in the accessible pores of the Grenzzonebereich.ee the second material layer as a third material layer a rubber dispersion or other substances bit either its own high coefficient of static friction or corresponding fillers intruded BATH ORIGINAL 309886/1032 ■■ ■