DE2736764A1 - MULTILAYER MOLDED PART MADE OF PLASTIC AND THE PROCESS AND DEVICE FOR ITS MANUFACTURING - Google Patents

Description

Dipl. Ing. PETER - C Sroka 4 Düsseldorf 11 PATENTANWALT O 7 T R 7 fi A DOMINIKANERSTR 37, POSTFACH7M IfOO / OH phone (0211) 574022 TELECR. fATENTBRYDCES DOSSELDORF

the 1o. August 19 1-4771 -4/8

Practice Industries, Ltd. Ube-shi, Yamaguchi-ken / Japan

Multi-layer molded part made of plastic and method and device for its production

The invention relates to a multilayer molded part made of plastic, e.g. B. on a multilayer film, a hose, a pipe or a blow-molded part with a certain structure of its cross-section, which consists of at least two thermoplastic synthetic resins is made. The invention also relates to a method and a device for producing such a multilayer Plastic molding.

In the previously known, multi-layer plastic molded parts, the interfaces run between the various Synthetic resins in the longitudinal direction, i.e. in the extrusion direction, plump 1 against each other and the individual layers lie over the Surface or the circumference of the molded part flat against one another.

The object of the invention is to provide a multilayer plastic molded part with a very specific cross-sectional structure

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create, in which the interfaces between the various synthetic resins in the longitudinal direction, ie in the extrusion direction of the molded part as well as transversely to the surface of the same are essentially streamlined. Such a structure of the cross-section is characterized in that the mechanical properties of the multilayer plastic molded part differ greatly from one another in different directions, so that the molded part can be adapted to very different uses.

To achieve the object, the invention provides a multi-layer molded part made of plastic, which is used for its production as a tubular Hollow body is extruded in the longitudinal direction and consists of at least two thermoplastic synthetic resins, and which is characterized in that the molded part consists of at least two plastic layers that are inside the tubular hollow body form a spiral pattern and extend in the direction of extrusion, the portion of a substrate each plastic layer, which is determined by the extrusion direction and the radial direction of the hollow body. Has a streamlined shape and proceeding from the central region of the relevant hollow body section to its surface runs diagonally outwards opposite to the extrusion direction.

This structure of the cross section is the one mentioned above Task solved to create a plastic molded part, whose mechanical properties vary greatly in different directions. With the previously known extrusion processes and devices, such a structure of the cross-section is not possible.

Further features of the invention emerge from the subclaims.

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Embodiments of the invention are explained in more detail below with reference to the drawings. Show it:

Fig. 1-12 Section of multilayer plastic molded parts,

13 shows a section through a plastic molded part produced in a conventional manner,

14 shows a vertical section through a device for the production of plastic molded parts,

15 shows a section along the line XV-XV of FIG. 14,

16 shows a longitudinal section through the molded part during of extrusion,

FIGS. 17-21 show, in plan view, various embodiments of one part of the device for manufacturing of the moldings forming, rotatable die plate.

In a multilayer plastic molded part 1 'with a conventional structure, according to FIG. 13, the interfaces 3 ¹ between the various synthetic resins run in the longitudinal direction parallel to the direction indicated by an arrow Y, in which the extrusion takes place.

According to FIG. 16, there is a multilayer plastic molded part 1 from a tubular hollow body 23, for example a tubular body made of film material, which consists of at least composed of two synthetic resins.

The individual synthetic resin sections A, B, ... are multiple Spiral arranged; this runs inside the hollow body 23 on its lateral surface and in the direction of arrow y, i.e. in the direction of extrusion. The section through a substrate 2 of each synthetic resin section A, B, ... has in the extrusion direction Y and in the radial direction streamlined and runs 1 to 12, starting from the central region of the hollow body 23, opposite to the extrusion direction Y at an angle outward.

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Of course, the multilayer plastic molding, i.e. the previously mentioned tubular hollow body 23, in the extrusion direction Y cut open and used as a sheet or sheet of foil material.

In the embodiments according to FIGS. 1 and 2, the interfaces 3 between the various synthetic resins of the molded part 1 shows a substantially symmetrical U-shape or streamlined shape in longitudinal section. In the embodiment according to Fig.

1, each boundary surface 3 extends up to the two outer surfaces of the multilayer plastic molded part 1. In the exemplary embodiment according to FIG. 2, the boundary surfaces 3 reach the two Outside areas, on the other hand, are not. In both cases, however, each substrate 2 has a U-shape or streamlined shape with sections which, starting from the central area, are directed obliquely outwards and connected to one another in the central area

In the embodiments according to FIGS. 3 to 5, one runs Substrate 2 of the two synthetic resins of the plastic molded part 1 is not symmetrical about the midline, but one section is long and the other is short.

In the embodiments according to FIGS. 6 and 7, the substrate is of the synthetic resins only present on one side. In the embodiments according to FIGS. 8 and 9, a substrate 2 of the two plastics is without connection in the middle and on both sides of the molding present. According to Fig. 1o overlap Substrates 2 according to FIG. 3 and the substrates 2 according to FIG. 4 face one another both on the left and on the right side.

In the embodiment of Figure 11, the substrates appear

2 of the two synthetic resins as points in the middle area of the molded part, while in the embodiment according to FIG Substrate 2 of the two synthetic resins goes through in the middle area in the longitudinal direction.

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In all embodiments according to Flg. 1 to 12, two types of substrates 2, which differ in terms of the plastic forming them, can be arranged in parallel and alternating with one another in the extrusion direction, or at least three types of substrates 2 which are different in terms of synthetic resin and which are arranged parallel to one another can be present and form a specific, regularly repeating pattern. The exemplary embodiment according to FIG. 10 is, for example, a composite molded plastic part 1 which consists of at least two synthetic resins. In this embodiment, the type and composition of one or both of the synthetic resins appearing on the front of the plastic molding are selected to be different from one or both of the synthetic resins appearing on the back of the plastic molding. At least two synthetic resins are mixed with one another in such a way that a multilayer structure results in a section through the molded part. With regard to at least two out of three sections that run in any three axes that cross each other perpendicularly, the mixed state of at least two synthetic resins is asymmetrical. *

The multi-layer plastic molded part with the aforementioned special structure has, compared to the conventional, multi-layer plastic molded parts, in which all interfaces between two different synthetic resins run parallel to the extrusion direction, or compared to a single-layer plastic molded part, which was produced in a plastic mixing process , the following advantages:

1. When synthetic resins that differ in their mechanical properties, for example a crystalline polymer and a kind of rubber, or a highly elastic synthetic resin and a synthetic resin with low elasticity together for Use come, so a plastic molding can be produced in which the mechanical properties in two Directions are extremely different, namely in the direction of extrusion and in the transverse direction across the surface

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of the form. For example, you can make a plastic molded part, which is very in one direction is stiff and has rubber-like properties in the other direction. In addition, one can use a slide, a Sheet or tube obtained which has a slippery surface and a non-slippery surface, or a molded part with an adhesive and a non-adhesive surface. Such anisotropic properties cannot be achieved with any of the conventional molded parts that have been produced in a plastic mixing process or as herkÖHBÜche multi-layer plastic molded parts.

The extent of the aforementioned difference can be changed by changing the shape of the substrate 2 of one of the at least two synthetic resins changes. Since the substrate 2 can be arbitrarily changed by As the extrusion conditions change, a variety of multilayer plastic moldings, which can be found in differ in their anisotropic properties, produce them with the help of the same extruder. If the length of the substrate 2 one of at least two synthetic resins in the extrusion direction is selected to be very long, in this way a plastic molded part is obtained in which there are many layers across the width or in the lateral direction available. If synthetic resins are combined in a suitable manner and thus a number of interfaces are present, molded parts can be produced which have a special thermal conductivity as well as a conductivity for sound waves and light. For example, let Plastic molded parts with a very low coefficient of thermal conductivity, very high sound attenuation or anisotropic light conductivity or reflectivity can be produced.

On the other hand, if the length of the substrate 2 is greatly reduced, a structure is obtained which, in section, has a large number of gently sloping synthetic resin layers which overlap each other in the extrusion direction. It can be

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accordingly a plastic molded part with very anisotropic mechanical Produce properties in which the gas permeability or the like. not just of the type of one of the the synthetic resins forming the molding is determined.

5. Even if synthetic resins with low binding power, e.g. polyethylene and nylon, used to manufacture the multilayer plastic molding, can thus have good binding properties achieve that any adhesive can be dispensed with.

6. Inflatable sheets made from a single synthetic resin, for example Polyethylene, polypropylene, nylon or the like. exist, have a low level, especially in a certain direction Impact resistance, so that so-called longitudinal cracks easily arise. In the case of the plastic molding with the one described above This disadvantage can be largely eliminated by using as one of the components of the special design Molded part a rubber or the like. used with good impact resistance.

7. In the multi-layer plastic molded part 1 according to FIGS. 1, 3, 4, 6, 8 and 1o there are different synthetic resins on the surface. One can therefore look at the surface in Provide suitable synthetic resins with high adhesive properties or good thermal insulation properties. In addition, at the plastic molded parts 1 according to FIGS. 2, 5, 7 and 9 ensure that synthetic resins that are not on the surface should appear, be limited to the interior of the molded part, and that only synthetic resins on the surface appear with the required properties.

8. If plastics that contain dyes, e.g. kaolins or dyes in combination, are used, so can be a plastic molded part, for example in the form of a film, a hose, a pipe or a Manufacture blow molded articles with spiral patterns.

The following is an apparatus for producing the plastic molding described.

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FIGS. 14 and 15 show an embodiment of a device for the production of plastic films using the upward blow molding process. According to FIGS. 14 and 15, there is a stationary die 5 provided with an annular slot 6. At the bottom, i.e. the front of the stationary die 5 is located a rotatable die 7 which rests tightly on the stationary die 5 as it rotates. Both the inner and the outer wall of the annular slot 6 run, as shown in Fig. 14, perpendicular or slightly inclined. With 8 is a spacer, with 9 a base for the die. The stationary die 5 and the spacer 8 are with the help of screws 1o or the like. attached to the base 9. That rotatable die 7 is arranged to be rotated between the stationary die 5 and the base 9 can, namely via a sprocket 11 which is arranged on a part of the rotatable die 7, and a chain. Of the Drive takes place by an electric motor, not shown, or the like .. On a part of the circumferential contact surface between the rotatable die 7 and the base 9 are provided with seals 25, and on a part of the circumferential contact surface between the rotatable die 7 and the stationary die 5 Pressure needle bearings 12. In the contact area between the rotatable die 7 and the stationary die 5 are located several outlet openings 13a to 13f for the synthetic resin. They are arranged with a certain distance from each other and lie in the area of the circle in which the annular slot 6 of the stationary die 5 is also located. In the base 9 there are inlet openings 14 and 15 for the synthetic resin, which are connected to the outlet openings 13a to 13f. In the interior of the lower section of the rotatable die 7 there is an annular groove 16 in the exemplary embodiment L-shaped cross-section and an annular groove 17 also with an L-shaped cross-section. Every second opening of the outlet openings 13a to 13f for the synthetic resin, namely the outlet openings 13a, 13c and 13e, are connected to the groove 16 via a channel 18 connected, while the groove 16 via a channel 19 with the

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Has inlet opening 14 for the synthetic resin connection. The remaining outlet openings 13b, 13d and 13f have a channel

20 connection with the groove 17, which in turn has a channel

21 is connected to the inlet opening 15 for the synthetic resin. In the embodiment according to FIGS. 14 and 15, there are six rectangular outlet openings 13a to 13f for the synthetic resin available. The outlet openings can also be round, slot-shaped or oval; their size is not strictly limited but can be chosen freely. The number of outlets can also be freely chosen, provided

that there are at least two outlet openings. For example, there can be 88, 100 or 200 outlet openings 13a, 13b ... be provided for the synthetic resin. In practical operation it has been found that in the presence of a quite a large number of outlets even then, when the rotatable die 7 rotates slowly, a finer structure is created in the plastic molding produced and in the generally better results are achieved. The wall surfaces the outlet openings 13a to 13f can run vertically or slightly obliquely.

In the embodiment described, two inlet openings 14 and 15 for the synthetic resin and two annular grooves 16 and 17 are present. The number of inlet openings and grooves can, however, be chosen arbitrarily, depending on the plastics to be processed, again provided that the number of openings and grooves is at least two. The inlet openings 14 and 15 for the synthetic resin are connected to two different extruders, not shown. With 22 an air line is designated.

In the embodiment according to FIG. 14, the inlets of the grooves 16 and 17 in the interior of the rotatable die 7 are directed horizontally. From this fact, there are the following advantages. Even if the pressure is fed to the extrusion of the

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Synthetic resin is relatively high, so the force, which the rotatable die 7 or the stationary die 5 after seeks to move up, reduced and the torque necessary for driving the rotatable die 7 reduced. The extrusion process can therefore be carried out in an economical manner and the service life of the extrusion device can be extended will. The embodiment described therefore has advantages compared to an arrangement in which the inlets of the grooves 16 and 17 are arranged vertically below the rotatable die 7.

At 24 is a coolant channel provided in the base 9 of the device designated. This enables temperature control when the supplied plastic is caused by the rotation of the rotatable die 7 has been excessively heated. Of course, a heating device, not shown, is provided to the Heat up the extrusion device partially or completely before the start of the extrusion process. The extruder needs during operation not to be cooled, but you can continue to heat them.

If a multilayer plastic molding 1 with the in the Fig. 1 and 2 shown cross-section is to be produced, an electric motor, not shown, is switched on, which the rotatable die 7 drives with the required speed, e.g. 1oo rpm, and the stationary die 5 is via the Air line 22 supplied with compressed air. At this stage of manufacture, separate extruders, not shown, are used the inlet openings 14 and 15 continuously fed various synthetic resins. Under "various synthetic resins" are To understand resins that differ in their chemical structure, physical and chemical properties, e.g. in the molecular weight, the distribution of the molecular weight, the external nature and the mixing ratio, the optical Properties and / or the components and mixing ratios of the plastic mixtures.

The synthetic resin supplied via the inlet opening 14 as well

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the synthetic resin, which is supplied via the inlet opening 15 moves through several outlet openings 13a, 13c and 13e and through further outlet openings 13b, 13d and 13f, which revolve on the same circular path. The synthetic resins are then continuously through a stationary, annular Pressed slot 6, which is located in the area of the same circle as the outlet openings 13a to 13f. Thereafter the plastic in the form of a film tube, i.e. a hollow body 23, is continuous through the annular slot 6 extruded. The tubular film produced in the extrusion process is inflated and stretched, cooled and wound on a drum like the conventional one Process for producing inflatable sheeting is the case.

In the device according to the invention, several outlet openings 13a to 13f for synthetic resin are on the same circular path moves and the synthetic resins that come from adjacent outlet openings are extruded into the annular slot 6 are different from each other. At a certain Accordingly, different types of plastics are extruded alternately in place of the annular slot 6. The material occurs then in the form of a film tube 23, the Sectional views and the structure change as shown in Fig. 16 is shown; this happens depending on factors such as the resistance that the wall surface of the annular Slot 6 exerts, and the speed at which the Film tube 23 is wound up. As a result, there is obtained a multilayer plastic molding with a Sectional structure according to FIG. 1. In the film according to FIG. 16, the letters A, B, C, D, E and F denote the plastic sections emerging from the outlet openings 13a, 13b, 13c, 13d, 13e and 13f designated.

If, viewed in the radial direction, the width of each exit opening 13a to 13d is changed, a plastic molded part according to FIG. 2 can be produced. To multilayered

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Plastic moldings with those shown in FIGS. 3 to 12 To produce cross-sections, it is advisable to determine the position, size and shape of those provided in the rotatable die 7 To select outlet openings 13 in a manner suitable for the purpose, as shown, for example, in FIGS 21 is shown. If a rotatable die 7 according to FIG. 17 is used, a plastic molded part is obtained with a Sectional structure according to FIG. 4; if the position and the size of the smaller outlet openings 13 are changed, so arise Plastic moldings according to FIGS. 3 and 5 to 7. When used of a rotatable die 7 according to FIG. 18, plastic molded parts according to FIGS. 8 and 9 are produced, and when a rotatable one is used 19, a plastic molded part is produced according to Fig. 1o. If a rotatable die according to FIG. 2o is used, a plastic molded part according to FIG. produce, and when using a rotatable die according to FIG. 21, a plastic molded part according to FIG. 12 is produced.

According to the invention, a multilayer plastic molded part 1 with the cross-sectional shapes shown in FIGS. 3 to 12 is produced with the aid of a device to which the following parts belong: a stationary die 5 with an annular slot 6; a rotatable die 7 which is arranged on the front side of the stationary die 5 and rotates close to the stationary die 5; a plurality of outlet openings 13 which are provided in the rotatable die 7 and bear against the stationary die 5 , and which are arranged over the circumference at certain distances from one another, namely on the same circular line as the annular slot 6 of the stationary die 5, with to the outlet openings 13 of the rotatable die 7 include a number of first outlet openings 13A and a number of second outlet openings 13B. The first and second outlet openings 13A and 13B are arranged in such a way that at least one second outlet opening 13B is located between two adjacent first outlet openings 13A, and that the center points

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of the first and second outlet openings 13A and 13B in a radial direction Direction are alternately offset from one another, as shown, for example, in FIGS. 17 to 19 and 21; and at least two inlet openings 14 and 15 for synthetic resin, which with the aforementioned outlet openings 13A and 13B connection to have. Of course, when the center of the first outlet opening 13A is viewed in the radial direction, coincides with the center point of the second outlet openings 13B of the device, as shown for example in FIG and 2o is shown, a multilayer plastic molding 1 according to FIGS. 1, 2 and 11.

According to FIGS. 17 to 21, the first outlet openings change 13 A and the second outlet openings 13B in the circumferential direction from each other individually; but it can also have two or more outlet openings 13 of the one type between two adjacent Outlet openings 13 of the other type may be arranged; Finally, the aforementioned alternate can also be used Arrangement and every third arrangement can be repeated in any order.

Since the multilayer plastic molding according to the invention the previously described, has a very specific structure, give way to the mechanical properties of the molded part in different directions very strongly from each other. The multilayer plastic molding according to the invention is therefore a very high quality molded part. In addition, a multi-layer Manufacture plastic molded part very easily and simply using a mold with the structure described above.

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Claims (8)

Claims / 1.] Multi-layer molded part made of plastic, which is part of his ^ - ^ Production as a tubular hollow body in the longitudinal direction is extruded and consists of at least two thermoplastic synthetic resins, characterized in that the molded part (1) consists of at least two plastic layers, which form a spiral pattern inside the tubular hollow body and run in the direction of its extrusion, the portion of a substrate (2) of each plastic layer passing through the extrusion direction and the radial Direction of the hollow body is determined, has a streamlined shape and, starting from the central region of the hollow body section in question, runs obliquely outwards towards its surface opposite to the extrusion direction. 2. Molding according to claim 1, characterized in that it is cut open in the extrusion direction and forms a film. 3. Molding according to claim 1, characterized in that the interfaces (3) between different plastic layers are streamlined and have a substantially symmetrical U-shape in the section determined by the extrusion direction and the radial direction of the hollow body. 4. Molding according to claim 1, characterized in that the boundary surfaces (3) between different plastic layers in the section determined by the extrusion direction and the radial direction of the hollow body extend at least up to a surface of the molding. 5. A method for producing a multilayer plastic molded part according to claim 1, characterized in that at least two different thermoplastic synthetic resins from a large number of first and second outlet openings 8098U / 0563 gene (13A and 13B) are extruded, which are provided in a rotatable die (7) and at certain intervals on a Circular line are arranged, after which the synthetic resins through a provided in a stationary die (5), annular Slot (6) are extruded, which is in the area of the same circular line as the first and second passage openings (13A and 13B) and is opposite to these. 6. Device for producing a multilayer plastic molded part according to claim 1, characterized in that a stationary die (5) with an annular slot (6) with its front side opposite a rotatable die (7), which lies tightly against the stationary die (5) rotates that in the rotatable die (7) a plurality of outlet openings (13A and 13B) is provided for synthetic resin which lie close to the stationary die (5) and are arranged at certain intervals on the same circular line are, in the area of which there is also the annular slot (6) of the stationary die (5), with the Outlet openings of the rotatable die (7) a group of first outlet openings (13A) for extruding one of at least two thermoplastic synthetic resins and one Group of second exit ports (13B) for extruding the other of at least two thermoplastic synthetic resins include, and that at least two inlet openings (14, 15) are provided for synthetic resin, which connection with the first and second outlet openings (13A, 13B). 7. Apparatus according to claim 6, characterized in that there is at least one second outlet opening (13B) between each two successive first outlet openings (13A) is located. 8. Apparatus according to claim 6, characterized in that the centers of the first and the second outlet openings (13A, 13B) alternately offset in the radial direction 8098U / 0563 are arranged to each other. 8098U / 0563