DE2051223A1 - Mfg plastics foils with rhomboidal patterns - of increased thickness - Google Patents

Abstract

A rhomboidal open mesh plastics foil is brought into contact with an extruded plastics foil which is still in thermoplastic state, the two foils are laminated together and the laminate oriented in one or both directions. Open mesh foil may be made from a high polymeric thermoplastics material having a lower m.pt. and the orientation is carried out at a temp at which the open mesh plastics foil is in a thermoplastic state.

Description

Ancestors for the production of a flat structure, consisting of a Plastic film with thickening points made of plastic and arranged in a grid-like manner and sheet-like structure produced according to the method A sheet-like structure made of a plastic film with grid-like thickening points, also made of plastic, can fulfill different purposes, depending on the effect of the thickening points in is moved to the foreground. This effect is particularly physical, sometimes also of an aesthetic nature.

The aesthetic effect is mainly based on the grid pattern and can be achieved by different coloring of the relief-like contrasting lattice structure highlighted in relation to the base layer, or if the color is the same, by the different light permeability of the base film and thickenings. In such The materials used for decoration and packaging play the low part The final price of the product naturally plays a major role.

Of the physical properties, the main one is tensile strength to call. The tear strength is important for many purposes. Such Products are in one already known in another form. For example Plastic foils laminated with fabric have a higher strength than simple ones Foils. Textile threads embedded in the foils also increase the strength. Her However, production is labor-intensive and the products are therefore expensive.

It has also been suggested (Austrian patent specification No. 216 755), in a device for the production of plastic films according to the Film blowing process simultaneously around the film tube by means of a cross of thread nozzles to form a network of parallel or crossed threads. The two Forms are in a still soft state with expansion of the hose and possibly united by stretching the threads.

The resulting structure can be used as a thread-reinforced plastic film be addressed. The threads are only Uber because of their round cross-section a small connection surface is glued to the base film. So you let go rub off relatively easily. At the crossing points of the threads, knot-shaped ones are created Elevations that stand out from the surface and are an additional possibility of attack for abrasive forces.

From the point of view of the apparatus it can be said that what has been discussed Process for its implementation requires a blown film tool with thread use must be equipped that rotate around the annular gap nozzle. Because of the high Working temperatures, such rotating elements are subject to high wear and tear subordinate. They also make the construction costs of the system considerably more expensive, in particular when a crosshair is to be reached.

In addition, the pattern of the thickenings is not changed can.

According to the invention, the method for producing a flat structure is made of plastic with thickening points arranged in a grid-like manner, characterized in that that a lattice-like cut, thermoplastic plastic film (lattice film) with a further, a foil torch tool (extruder nozzle, calender rolls) Plastic film (round roll) is brought into flat contact, with the two Glue the foils together, and that the plastic foils together in at least one Direction to be extended.

There is a great advantage of this method according to the invention that the production of such flat structures with the known facilities for the production of plastic films can be carried out and only some additional equipment necessary to bring one or more grid foils flat to the base foil are. So they are the most common devices for the production of plastic films such as film blowing tools, slot dies and calendar rollers for implementation of the process can be used equally.

The invention also includes various modifications of such defined process whereby products with different properties are manufactured will know.

According to the invention, the plastic sheet with is grid-like arranged thickening points characterized in that the thickening points form a coherent, lattice-like, flat network, whereby the web and the branches are essentially of the same thickness.

In the case of a special form of the planar structure according to In the invention, the thickening points consist of a stretched or stretched, high polymer thermoplastic material.

In a further form of training, the thickening points have bead-like thickened edges. The thickening points exist in another form of training made of a thermoplastic foam plastic.

Another embodiment of the flat structure is characterized by that the base role is arched between the thickening webs, this means that the base film forms bowl-shaped bubbles. In addition, the bulges the base film is glued to a coherent surface layer that covers it or welded.

The method and product according to the invention are described below based on an exemplary embodiment shown in the attached drawings described in more detail.

It shows: FIG. 1 schematically a device for manufacturing the product according to the invention in a view from one side, FIG. 2 shows the device according to FIG FIG. 1 shows a view from another side, FIG. 3 shows a view of the manufacture of the product used slotted film, Fig. 4 is a view of a product from above, FIG. 5 shows a cross section through the cut product along the line I-I of Fig. 4, Fig. 6 a partial section greatly enlarged, Fig. 7 a further, slotted film used for the manufacture of another product, Fig. 8-10 some further products in a view from above, FIG. 11 the product according to FIG. 10 in section and FIG. 12 shows a variant of the product according to the 10 and 11, in section.

The arrangement according to FIGS. 1 and 2 shows an arrangement for the production of plastic films by the known blown film process which a film tube is extruded upwards. An extruder 1 has a Input funnel 2 for the granulate and a film blowing tool 3. This blown film tool has, in a known manner, an annular nozzle for ejecting the film tube vertically up. Through a line 4, which opens centrally into the ring nozzle from below, support air is blown into the film tube 5. By means of a folding device 6 the hose is flattened and pulled off by rolling 7 upwards. The film tube is deflected downwards again via a system of deflection rollers 8, flattened and cut into two sheets of film by means of cutting knives 9, which are then wound onto two separate winding devices 10.

For example, high pressure polyethylene is used under normal conditions processed, it is processed with a blow ratio of 1: 5, i.e. with a 5-fold Enlargement of the circumference of the film tube compared to the circumference of the ring diameter worked. This initially results in a relatively large expansion of the film across their direction of movement. Of course, lower inflation ratios are also possible from 1: 2.5 to 1: 3 easily feasible. The deduction ratio is approx. 1 : 8. The film material is thus stretched in two directions in a known manner or plugged.

It is advisable to add up to 30 ffi of low-pressure polyethylene to the high-pressure polyethylene add, whereby the polishing tube becomes stiffer and the temperature of the film tube higher can be chosen, what the welding of the film tube with the slit Foil or a net facilitated.

Starting from this known blown film process is now after Method according to the invention in a completely new way a plastic lattice film or a net welded directly onto the film tube. For this purpose, e.g. synchronous from two supply rolls 15 arranged on opposite sides, one lattice film each or a net 16 is unwound, brought up to the film tube 5 via pulleys 17 and applied by baffles 18 to the circumferential surface of the film tube and welded on.

In the case of film tubes with a relatively small diameter With an appropriate design of the guide plates 18 it is also possible to use the whole Cover the circumference of the film tube with a single net or a lattice film. Since it is planned anyway the tube later in two sheets of film To separate, the net is laid out in such a way that the net edges are at one of the dividing points lie.

The material used for the mesh 16 should have thermoplastic properties exhibit. Its softening temperature should not be significantly higher than that the material of the film tube. The mesh material can be unstretched or pre-stretched be.

In the latter case, it should not be stretched to its yield point otherwise it would not take part in the expansion of the film tube and then either falls off or rips the hose. Are very suitable for the net next to common thermoplastics such as polyethylene lower rest. high density, Polypropylene, polyamide, polystyrene and all other thermoplastics, including copolymers Materials such as copolymers of ethylene with vinyl acetate or acrylates as well the ionomeric synthetic resins which crosslink reversibly at room temperature. The latter are Particularly suitable when it comes to the good hot bondability and abrasion resistance of these resins arrives.

A grid folic or a mesh or two thereof are generally used directly above the film blowing tool 3 with the film tube 5, i.e. the Grundfolle, tied together. The film tube is not yet in this zone or only partially expanded. By touching the network 16 or the like takes. practically immediately the temperature of the surface of the film tube 5, the latter is cooled down somewhat by the heat balance.

The network 16 oddgl. softened immediately by the increase in temperature and welds itself intimately to the base film. When processing certain raw materials it may be necessary to heat the network 16 by means of a heat source 19 in order to a good weld to bring about with the film tube 5, and then to cool the combined foils by means of an air cooling ring 20, thus the stretching of the lattice film or the network particularly increases the strength e.g. by aligning the semi-crystalline areas of the high-polymer plastic the grid film or the like ..

With the subsequent increase in volume of the film tube 5 the network 16 or the like. expanded. Because the net is firmly welded to the base film it does not tear in spite of the relatively large exposure. It is also possible, as a starting material for the network 16 or the like. to use a slotted film, the slots of which are only opened when stretching after welding with the film tube to open. This is a particular advantage of the method according to the invention, since a slit film that is not connected to an unslit film, inevitably tears open at the ends of the slits when stretching, if they are perpendicular to the direction of rejection is stretched.

The net structure on the film also makes it easier to wind up the disassembled into two lanes, with a lattice film or the like. welded film tube and in particular later the unwinding, since the individual layers of the sheet-like structure do not stick to each other.

It could, for example, be provided with a film with slits 24 mm long lattice structures with meshes 8 cm long and 2.5 cm wide are created, the slits extending in the direction of movement of the tubular film. The originally 3 mm wide strips between the slits were narrow A web of approx. 1 mm width has become.

FIGS. 3-5 show such a product, FIG. 3 showing the represents the original, slotted film. From the cross section of Fig. 5 it is clear that the two starting materials are completely welded together. As the enlarged section of FIG. 6 shows, the edges 21 of the webs are bead-like thickened.

FIGS. 7 through 9 illustrate other products that can be produced according to this Process have been produced, FIG. 7 again showing the slit starting film represents. To produce the product according to FIG. 8, the slit film was used 16 fed in such a way that the slots are in the direction of movement of the film tube 5 stretched. In comparison to the product according to FIG. 4, the web and node surfaces are wider. On the one hand, due to the oversized coloring of the plastics for the base film 5 and for the network 16, on the other hand, the aesthetic effect can be increased. That The product according to FIG. 9 is made with the same slotted starting material according to FIG Fig. 7 has been generated, but the slots were oblique to the direction of movement of the film tube 5. The aesthetic effect of the pattern is special stressed.

It is also possible to specifically stretch the network 16 less than the film tube, namely that it is at a slightly higher point of the conical transition to the inflated tube shape is welded.

The new physical properties of the product according to the Invention can be used in various ways.

Apart from the fact that the tensile strength for the same square meter weight of a product according to the invention is higher than the one a film of uniform thickness, the tear strength is very important increased, since there is no bite in the base film between the webs propagates beyond the webs. The 8 can be used for production of packaging material, for the storage of food, such as flour, in which a certain gas exchange through the packaging film is desirable. Dsbei the thickness of the material of the base film can be chosen so weak that a Diffusion of the oasis through the base film is possible while the lattice structure ensures the necessary strength. An additional advantage is achieved here, namely that sacks made of such packaging material are stackable because they are due to the lattice structure and because of the aforementioned bead-like edges 21 not against each other slip. The grid-like ribbed surface structure can also be used to make floor coverings anti-skid on Rempen, or to increase friction for conveyor belts etc.

In an alternative to the method according to the invention, a film is used generated with a bubble structure according to FIGS. 10 and 11. As a starting material for blowing the film tube 5, a relatively thin film is selected while the network or the like consists of a thicker, firmer film. She is in the same Manner as shown in Fig. 7, slotted. There is a strong overpressure inside of the film tube 5 made opposite bussen. The expansion of the Film tube 5 limited by the resistance of the network 16, whereby by the Effect of the overpressure inside the film tube parts of the base film5 between be formed into small bubbles 22 through the webs of the lattice film.

This product can e.g. in packaging. The structure can also be used on the blister side an additional surface layer 23 can be glued over, as in Fig. 12 in section shown.

The same effect can also be achieved using a a little more solid material for the film tube 5, if the tube bussen is heated, the expansion temperature of the network or the like. 16 must be higher than that of the base sheet. The uncovered areas of the base film then soften, before the strength of the network has decreased too much, due to the pressure difference these spots are formed into bubbles.

The method according to the invention also allows the possibility of the network or the like. 16 to be used as a strength-giving element.

So it is only possible thanks to the present invention Peel off upward film made of a material with a relatively high melt index. The net 16 then forms the supporting net from which the film tube 5 hangs.

Depending on the desired end product, the film tube can be pulled off 5 Mch open can be done in different ways: First, the hose can be used as usual folded without special measures and pulled off the take-off rollers 7. Due to the high stickiness of the material used for the film tube 5, e.g. polyethylene With vinyl acetate, the two film walls stick together as a result of the pressure then completely coincide between the rollers 7 and a coherent one is formed Plastic film with a grid structure welded on both sides.

Second, a release agent, such as Talktim, can be placed in the tubing prevents sticking from being introduced. From a hose you can then produce two foils with a one-sided network structure.

Another product with novel properties is obtained, when the mesh structure is formed from foam. For this purpose one can use the Starting material for the network 16 or the like. a propellant such as azodicarbonamides, to add, which is caused by the heating when it comes into contact with the tubular film 5 or is activated by a heat source 19. But it can also be a thermoplastic Foam in the form of a more or less thick film can be used, the front the unification with the film tube 5 is slit.

However, the blown film process is not the only process that can be used in connection with the method according to the invention. the Grundfolle can also in a known manner by means of a wide slot nozzle or by means of Xalander rolls are manufactured. Although also devices for biaxial stretching such films are known, linear stretching is common in this process. In the case of linear stretching, it is also possible to use a plastic film as the net 16, which are provided with slots running transversely to the direction of movement of the film web because the latter drsnen independently when stretching the film web, whereby the lattice structure is created.

The method according to the invention is in no way similar to that in the description of the embodiment mentioned high-pressure polyethylene as the material rar the base film bound. Depending on whether a blown film blower is used to carry out the process, one System with a slot nozzle or a pair of rollers can be used accordingly suitable thermoplastics are used, such as printed polyethylene, Acrylates, polyamide, polycarbonate, thermoplastic polyurethane, polystyrene, polyvinyl chloride, Tentulose acetate etc.

Claims (20)

P a t e n t a n s p r ü c h e Method for producing a sheet-like structure made of plastic \ with latticed thickening points, 1 r r a g e k e n n n z e i c h n e t, that a lattice-like cut, thermoplastic plastic film (lattice film) with another, a film tool (extruder nozzle, calender rolls) in the hot plastic Condition leaving plastic film (base film) brought into flat contact is, whereby the two foils are welded together and that the plastic foils be expanded together in at least one direction. 2. The use of a strength-increasing stretchable, made of still polymeric Plastic lattice film as a lattice film that can be placed on top. 3. The use of a slotted plastic film as a lay-on Lattice film. 4. The method of claim 1, d a d u r c h, n n -z e i c h n e t that the OitterfolLe is heated before it is placed on the base film. 5. The method of claim 1, d a d u r c h g e k e n n -z e L c h n e t, dus a plastic with a lower softening temperature as the material of the lattice film as the plastic of the base sheet is used, and that stretching the plastic sheets takes place at a temperature at which the plastic of the lattice film is in the plastic State. 6. The use of one impregnated with a foam blowing agent thermoplastic plastic film as a grid film. 7. The method according to claim # using a grid film according to Claim k, d a d n r e h g e n n z e 1 c h n e t that the lattice film for the purpose Activation of the foam blowing agent heat is supplied. 8. The method according to claim), d a d u r e h g e k e n n -2 C i c h n e t, that. a thermoplastic material has a higher base film: melt index 535 the plastic used for the base film is that there is a pressure gradient between the two sets of the base film is generated, and that the base film according to their Association with the lattice film heated to at least its softening temperature is, eo that the sub-areas of the The base film can be blown into small blowers under the effect of the pressure gradient. 9. The method according to claim, d a d u r c h g e k e n n -2 e 1 e r e t that the two plastic sheets are on the convex side of the vesicles with a contiguous surface layer are covered and that the surface layer is welded to the calottes of the vesicles. 10. The method of claim 1, d a d u r c h g e k e n n -2 t 1 c Not that the base film is extruded from a slot die, and that the synthetic peat foils are pulled apart linearly in the pull-off direction will. 11. The method according to claim 1, d a d u r c h g e k e n n -z e 1 c n e t that the base film is formed between calender rolls, and that the Plastic foils are pulled apart at least linearly in the pull-off direction. 12. The method according to claim 1, d a d u r c h g e k e n n -z e 1 c h n e t that the basic roll on a film blow molding tool with a ring nozzle to a Film tube is extruded, and that the two plastic films by overpressure be pulled apart biaxially inside the film tube. 13. The method according to claim 12, d a d u r c h g e k e n n -z e i c n e t that the film tube is compressed in the warm plastic state of the base film so that the walls of the film tube are welded together. 14. Flat structure consisting of a plastic film with a grid-like pattern arranged thickening points> d a d u r o h g e k e n n n z e i c h n e t, that the thickening parts of a contiguous> grid-like perforated, flat network welded to the plastic film (5), the web of which and branching areas have substantially the same thickness. 15. Flat structure according to claim 14, d a d u r c h g e k e n nz e i c h n e t that the network (16) is made of a stretched, high-polymer thermoplastic Made of plastic. 16. Flat structure according to claim 14, d a d u r c h g e -k e n n z it does not take into account that the webs and the branched surfaces have thickened edges in the form of bulges (21) have. 17. Flat structure according to claim 14, d a d u r o h g e k e n nz e i n e t that the network (16) consists of a. thermoplastic is made of plastic. 18. Flat structure according to claim 14, d a d u r c h g e k e n n -z It is true that it has thickened areas arranged in a grid-like manner on both sides. 19. Flat structure according to claim 14, d a d u r c h g e k e n nz e i c h n e t that the base film (5) is arched between the thickening points is. 20. Flat structure according to claim 19, d a d u r c h g e k e n nz e i c h n e t that the bulges (22) of the base film (5) with a covering them Surface layer (23) glued or are welded.