WO2017221041A1 - Knurled multilayer polyolefin films for use as antiadhesive interleaves, as well as process and technological line for manufacturing the same - Google Patents

Knurled multilayer polyolefin films for use as antiadhesive interleaves, as well as process and technological line for manufacturing the same Download PDF

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Publication number
WO2017221041A1
WO2017221041A1 PCT/IB2016/000861 IB2016000861W WO2017221041A1 WO 2017221041 A1 WO2017221041 A1 WO 2017221041A1 IB 2016000861 W IB2016000861 W IB 2016000861W WO 2017221041 A1 WO2017221041 A1 WO 2017221041A1
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WO
WIPO (PCT)
Prior art keywords
film
layer
knurled
sleeve
temperature
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Application number
PCT/IB2016/000861
Other languages
French (fr)
Inventor
Przemyslaw Marcin LASKUS
Piotr LASKUS
Patryk Maciej LASKUS
Jaroslaw Pawel LASKUS
Kornel Jan LASKUS
Original Assignee
Laskus Przemyslaw Marcin
Laskus Piotr
Laskus Patryk Maciej
Laskus Jaroslaw Pawel
Laskus Kornel Jan
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Application filed by Laskus Przemyslaw Marcin, Laskus Piotr, Laskus Patryk Maciej, Laskus Jaroslaw Pawel, Laskus Kornel Jan filed Critical Laskus Przemyslaw Marcin
Priority to PCT/IB2016/000861 priority Critical patent/WO2017221041A1/en
Priority to EP16831510.9A priority patent/EP4214052A1/en
Publication of WO2017221041A1 publication Critical patent/WO2017221041A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/28—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer comprising a deformed thin sheet, i.e. the layer having its entire thickness deformed out of the plane, e.g. corrugated, crumpled
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/30—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/05—5 or more layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/516—Oriented mono-axially

Definitions

  • the present invention relates to knurled multi-layer polyolefin films for use as antiadhesive interleaves, in particular for rubber industry, and a process for manufacturing the same and technological line for implementing the method.
  • Knurled multi-layer polyethylene films are the materials traditionally used for this purpose.
  • the films have the following final characteristics: thickness of 40-180 ⁇ , width ranging from 50 to 2500 mm and density in the range 0,918-0,940 g/cm 3 .
  • Knurling reduces the area of contact with the rubber compound remaining in contact with the both sides of the spacer, thus it facilitates its separation from the rubber compound web being targeted for further processing.
  • patterns used for knurling usually: diamond, pyramid or line patterns.
  • Polyethylene is a preferred material for antiadhesive interleaves due to its susceptibility to processing, its flexibility and good yield point parameter; it also has good mechanical properties.
  • the films are used, in which individual layers consist of polyethylene with different molecular weights.
  • the individual layers of the multi-layer film are sometimes modified by adding other polymers, such as for example polypropylene(s), and various additives, such as plasticizers, dyes, pigments, antistatic agents, release agents, and the like.
  • spacers antiadhesive interleaves made of polyethylene films are disposable after a single use and as such the are post-production wastes, intended for disposal or recycling.
  • the aim of the invention is to provide a multi-layer film of polyethylene antiadhesive interleaves for the rubber industry and not only capable of reducing weight polyethylene post- production wastes in the industry, but also to provide a process of manufacturing such a film, as well as the production line for carrying out the method.
  • a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in form of a knurled strip, according to the invention is characterized in that it is made of a 1-9 layer polyolefin sleeve with the inner adhesive layer, subjected to blocking after being formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25-100 ⁇ and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation.
  • the multi-layer polyolefin film according to the invention has preferably the inner adhesive layer which is made of a mixture having a Vicat temperature below 70°C and consisting of:
  • the layers responsible for its mechanical properties are made of polymers and copolymers from the group of polyolefins having density of 0.900 g/cm 3 - 965 g/cm 3 .
  • a variant of a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, according to the invention is characterized in that the strip is obtained by cutting a 1-9 layer polyolefin sleeve formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25-100 ⁇ and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation.
  • the layers responsible for its mechanical properties are made of polymers and copolymers from the group of polyolefins having density of 0.900 g/cm 3 - 965 g/cm 3 .
  • the invention covers also a process for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, wherein streams of variety of different melted polyolefins are the co-extruded and subjected to blow molding to form a multi-layer polyolefin sleeve, and the resulting multi-layer strip is knurled at temperature above the softening points of the polyolefins used, which process according to the invention is characterized in that by blow molding a 1-9 layer polyolefin sleeve is formed by co- extrusion of different melted polyolefins, which sleeve is passed through nip rolls, and then subjected to unidirectional longitudinal orientation using a set of rollers of different temperatures and different speeds, till achieving at 70-120°C the film thickness reduction in the range of 2-7,5 times, from an initial value of 400-80 ⁇ , to
  • the composition of the manufactured multi-layer film is controlled gravimetrically and the automatic interoperational control of thickness of the manufactured multi-layer film is carried out.
  • polymers and copolymers from the group of polyolefins having density of 0.900 g/cm 3 - 965 g/cm 3 are used as a material for forming the layers responsible for the mechanical properties of the produced multilayer film.
  • the film sleeve is produced, wherein the inner adhesive layer is made of a mixture having a Vicat temperature below 70°C and consisting of:
  • the film is reheated to a temperature adjusted to the film composition, within the range of 70-120°C, by means of contacting the film with the heated rollers and then the thus heated film is directed to the heating rollers which rotate at different rotational speeds, and after reaching a reduction of thickness of the film in the range of from 1: 2 to 1: 7.5, the film is cooled from the temperature of orientation of the film to the ambient temperature.
  • the film is subjected to longitudinal edge cutting, and cut edges are recycled to the stage of the preparation of the blow molding mixture.
  • the central portion of the blocked film web obtained in result of the longitudinal edge cutting is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
  • the two independent film strips uniaxially oriented in the longitudinal direction, resulting form the longitudinal edge cutting are wound on two large bales using a two-reel winder, which bales are then - directly or at any time thereafter, individually transferred to a separate knurling station to an unwinder reel of the knurling station and the film strip is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
  • the present invention relates also to a technological line for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, as described above, comprising:
  • a winder which line is characterized in that between the system of nip rolls and the assembly for longitudinal edge cutting, there is an assembly for uniaxial longitudinal orientation comprising heating rollers which rotate at different rotational speeds and a system for cooling the film cooled from the temperature of orientation of the film to the ambient temperature.
  • the technological line according to the invention is also characterized in that the assembly for uniaxial longitudinal orientation is the MDO unit.
  • the technological line according to the invention preferably further comprises an assembly for gravimetric control of composition of the manufactured multi-layer film, as well as a device for automatic interoperation control of thickness of the manufactured multi-layer film.
  • the film according to the present invention i.e. the film subjected to the uniaxial longitudinal orientation and having a thickness reduced 30-60% depending on the final destination, as compared with the polyolefin spacers currently used in the rubber industry, without loss of strength and other performance benefits.
  • the film according to the invention is knurled, and the resulting pattern is designed to reduce the contact surface between the film and the rubber compound.
  • the sleeve of the multi-layer film without blocking is directed to the assembly for longitudinal orientation, and after the step of uniaxial orientation, the longitudinally oriented sleeve of multi-layer film is separated in step of longitudinal edge cutting into two strips of longitudinally oriented film, which strips separately are directed to the knurling operation step, either immediately after separation or after winding on two separate shafts.
  • the resulting knurled uniaxially longitudinally oriented multi-layer film is packaged according to customer's requirements. Due to the longitudinal orientation the knurled multi-layer film of the invention exhibits:
  • the longitudinally oriented antiadhesive interleaves of knurled multilayer film of the present invention are thinner than conventional ones, which significantly reduces the amount of post-production wastes. It also means a corresponding reduction in the load of equipment for storage and handling the bales of extruded rubber, thus helping to reduce wear and extend the life of the equipment.
  • Fig. 1 shows a block diagram of the method according to the invention
  • Fig. 2 shows a production line A for the manufacturing of a knurled uniaxially longitudinally oriented blocked multi-layer film for use as antiadhesive interleaves for rubber industry, and
  • Fig. 3 shows a production line B for the production of knurled uniaxially longitudinally oriented multi layered film for use as antiadhesive interleaves for rubber industry.
  • Fig. 1 in the present invention there are carried out three main processes: extrusion of a film, uniaxial longitudinal orientation and knurling of the uniaxially longitudinally oriented film.
  • the method further includes the auxiliary processes: gravimetric control of the composition of the produced film, and automatic interoperational control of the thickness of the film.
  • the method may be implemented in two versions: a continuous production process (Line A, as shown in Fig. 2) or process with technological break before knurling operation (Line B shown in Fig. 3).
  • the method of the present invention is adapted to the technological requirements associated with the use of a multi-layer polyolefin film in the form of a sleeve r2, with the adhesive inner layer (Fig. 2) that is subjected to blocking on the pulling nip rollers 3 that exert pressure to form a single strip of the multi-layer film.
  • the production line used in this embodiment of the present invention is composed of an extruder 1, a head 2 for blowing of the extruded film to form a film sleeve rl_, the nip rollers 3, passing through which results in obtaining a single strip of the multi-layer film fz being directed to a MDO device 4 for effecting the uniaxial longitudinal orientation, and then the longitudinally oriented film fo is directed to the knurling assembly 5 integrated into the production line A.
  • the knurled longitudinally oriented film mfo is received on a winder 6. Sections of the knurled longitudinally oriented film - according to the customer orders, are wound on separate bobbins.
  • the advantage of this variant is producing the final knurled multi-layer film in a single production cycle.
  • the line B shown in Fig. 3 is used for production, the line comprising an extruder 1, a head 2 for blowing the extruded film to form a film sleeve r2, the sleeve being unsusceptible to blocking, the nip rollers 3, passing through which results in obtaining a compressed sleeve of multi-layer film f in a form of strip, further directed to the MDO device 4 to undergo an uniaxial longitudinal orientation, and the longitudinally oriented film fo - after the operation of longitudinal edge cutting is in form of two separate strips of longitudinally oriented film fo which are directed to the two-reel winder 7a, 7b.
  • a ready for dispatching knurled film according to the invention for use as antiadhesive interleaves (spacers) for the rubber industry, produced in accordance with the process according to the invention using the production lines A and B as shown in Fig. 2 and Fig. 3 is identical and has the same performance characteristics, irrespectively of the production variant.
  • the present invention provides process for manufacturing a knurled multi-layer polyolefin film according to the invention, for use as antiadhesive interleaves for the rubber industry.
  • streams of different melts of polyolefins, preferably polyethylene, sometimes modified with other polymers or other additives and ingredients of refining character are co-extruded and then subjected to blow molding to form a multi-layer film sleeve, which is passed through the pulling assembly of nip rollers.
  • a multi-layer, including 1-9 layers, polyethylene film is obtained by using a device for the production of films by blow molding comprising the extruder 1 having a head 2, wherein the inner layer of the sleeve rl_ comprises very adhesive components, which are strongly susceptible to blocking, such as for example the acetate plastomer having a density less than 0.900 gm/cm 3 , EVA copolymers with a vinyl acetate content greater than 19% or lots more of the like materials.
  • the materials susceptible to blocking should have a Vicat temperature below 70°C.
  • the film sleeve, of which the inner layer has an adhesive component is squeezed by the pulling nip rolls 3 heated up to a temperature in the range 60-90°C and pressed with a pressure within the range of 3.0-7.5 bar, which results in blocking. In this way, after leaving the rolls 3 a single multi-layer strip fz - not the sleeve, is obtained.
  • the thus blocked strip is submitted to longitudinal orientation.
  • This process is carried out in the device 4 called MDO.
  • This process involves reheating the film.
  • the process of heating the film strip is carried out by contacting the material with the rollers, which are of suitable temperatures. Depending on the composition of the film rollers are heated to a temperature comprised between 70-120°C
  • the thus heated film is passed in the device 4 to the next heating rollers rotating at different circumferential speed. Roller speed differences affect the rate of longitudinal orientation.
  • the degree of orientation ranges from 1: 2 to 1: 7.5 depending on the desired final parameters of the film.
  • the film fo is subjected to longitudinal edge cutting, i.e. the left and right side uneven edges of the tape are cut off, the cut material is recycled to step the preparation of melt for blow molding, and the central (middle) portion of the strip is subjected to heating by a number of heating rolls and infrared radiators, and then - when film is heated above the softening temperature, it is subjected to knurling operation, providing the knurled pattern according to the customer's order using the knurling assembly 5.
  • longitudinal edge cutting i.e. the left and right side uneven edges of the tape are cut off
  • the cut material is recycled to step the preparation of melt for blow molding
  • the central (middle) portion of the strip is subjected to heating by a number of heating rolls and infrared radiators, and then - when film is heated above the softening temperature, it is subjected to knurling operation, providing the knurled pattern according to the customer's order using the knurling
  • the resulting knurled film mfo is wound round bales of a winder 6, adjusting the amount of current meters of film on each bale to request of the customer, and then the bales are packed on pallets.
  • the quality control in terms of uniformity, absence of air bubbles and mechanical damage is carried out.
  • the thickness of the multi-layer film is controlled automatically at various stages of manufacturing process.
  • composition of the coextruded individual layers of the multi-layer film is the composition of the coextruded individual layers of the multi-layer film
  • FX1001 - LDPE - is responsible for the mechanical parameters
  • Green 3011 - green dye Green 3011 - green dye.
  • Raw material compositions of the individual layers A, B, C and D are the same as in the above described embodiment, while instead of the layer E forming in the above embodiment the inner layer, layer A is repeated.
  • An exemplary raw material compositions of strip f that is not to be subjected to blocking, as referred to above, are given in the Table 2 below. The meaning of the symbols used therein, is the same as described above with reference to Table 1.
  • the film enters the MDO device 4 in the form of a sleeve r2 and after the longitudinal edge cutting operation the sleeve is split into two separate longitudinally uniaxially oriented multi-layer film strips fo.
  • the knurling assembly 5 is not an integral part of the technological line B of the present invention, but is a separate knurling station, including rewinder 8, the knurling device 5 and winder 6 to wind the film.
  • a multi-layered film is obtained by using a line for the production of films by blow molding.
  • the outer and inner layers of the sleeve have the same composition as the outer layer in the first embodiment of the invention, i.e. the sleeve r2 has no internal adhesive layer to enable blocking.
  • the temperature of the pulling nip rolls 3 is ca. 56°C, and the pressure is up to 5 bar.
  • the film behaves according to standards, i.e. after passing through the pulling nip rolls 3 it has the form of a strip retaining the original form of a sleeve r2, and as such is directed on to the MDO device 4, while after longitudinal edge cutting operation it splits into two separate strips fo which are wound by the two-reel winder 7a, 7b on large bales.
  • the so called jumbo rolls are transported to an unrolling device 8 of the knurling assembly 5 organized as a separate station.
  • the knurling process and temperature parameters thereof are the same as in the first embodiment of the invention.
  • the invention is further illustrated by the following examples, which specifically describes a process for manufacturing a knurled multi-layer polyethylene film for use as antiadhesive interleaves, in particular for the rubber industry. Comparative examples allow to assess the advantages of the inventive film.
  • An apparatus for forming films by blowing LDPE material was supplied, which was processed at a temperature of 180-230°C. During the blowing sleeve was cooled with the air stream and reached a temperature in the range of 40-80°C prior to being directing the pulling (stretching) nip rollers.
  • a multi-layer film was produced in the form of a sleeve, keeping the pinch rollers compression temperature to 56°C.
  • the pre-stretched multi-layer film sleeve was obtained, which sleeve after cooling down and longitudinal edge cutting has been split into two separate multi-layer film strips which were wound onto a separate rolls.
  • resulting oriented multi-layer film has undergone a process knurling.
  • Samples of the film obtained under the first or second embodiment was subjected to the following quality tests: strength, tensile strength, elongation at break.
  • Comparative film had a thickness of 100 microns and had embossed pattern identical to the film manufactured in accordance with the present invention. The results are summarized in Table 3
  • the invention has been described in detail with reference to the polyolefin film produced in the form of a sleeve by blow molding.
  • the same inventive concept can be successfully used in the production of multi-layer films of the knurled-layer film obtained by casting.
  • the second embodiment of the invention it is possible to control one of the two distinct longitudinally uniaxially oriented multi-layer strips to the knurling device integrated into the production line, the second winding shaft - for later transfer to separate knurling device representing a separate processing station.

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Abstract

The present invention relates to a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in form of a knurled strip, characterized in that it is made of a 1-9 layer polyolefin sleeve with the inner adhesive layer, subjected to blocking after being formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25-100 μιη and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation. The invention also relates to a film made in the form of a sleeve by blow molding, but without the inner adhesive layer and a film formed by casting. A process for manufacturing a multi-layer polyolefin film according to the invention, wherein streams of variety of different melted polyolefins are the co-extruded and subjected to blow molding to form a multi-layer polyolefin sleeve, and the resulting multi-layer strip is knurled at temperature above the softening points of the polyolefins used, according to the present invention is characterized in that the film is passed through pulling nip rolls, and then subjected to unidirectional longitudinal orientation using a set of rollers of different temperatures and different speeds, till achieving at 70-120°C the film thickness reduction in the range of 2-7,5 times, from an initial value of 400-80 μιη, to a final value of 25-110 μιη, and the thus obtained uniaxially oriented film is subjected to knurling and it is packed according to customer's requirements. A technological line for manufacturing a multi-layer polyolefin film according to the invention, comprising: a) an apparatus for co-extrusion of different polyolefin melts and forming the multi-layer polyolefin sleeve by blow molding; b) a system of nip rolls heated to a temperature of 60-90°C and operating under the pressure in the range of 3-7.5 bar; c) an assembly for longitudinal edge cutting of the blocked strip or a film sleeve; and d) an assembly for film knurling, according to the invention is characterized in that between the system of nip rolls and the assembly for longitudinal edge cutting, there is an assembly for uniaxial longitudinal orientation comprising heating rollers which rotate at different rotational speeds and a system for cooling the film cooled from the temperature of orientation of the film to the ambient temperature.

Description

KNURLED MULTI-LAYER POLYOLEFIN FILMS FOR USE AS ANTIADHESIVE INTERLEAVES, AS WELL AS PROCESS AND TECHNOLOGICAL LINE FOR MANUFACTURING THE SAME
The present invention relates to knurled multi-layer polyolefin films for use as antiadhesive interleaves, in particular for rubber industry, and a process for manufacturing the same and technological line for implementing the method.
In the rubber industry, there is a constant demand for antiadhesive interleaves as spacers for materials undergoing easy gluing, such as webs of calendered rubber compound. Knurled multi-layer polyethylene films are the materials traditionally used for this purpose. The films have the following final characteristics: thickness of 40-180 μιη, width ranging from 50 to 2500 mm and density in the range 0,918-0,940 g/cm3.
Knurling reduces the area of contact with the rubber compound remaining in contact with the both sides of the spacer, thus it facilitates its separation from the rubber compound web being targeted for further processing. There is a variety of patterns used for knurling - usually: diamond, pyramid or line patterns.
Polyethylene is a preferred material for antiadhesive interleaves due to its susceptibility to processing, its flexibility and good yield point parameter; it also has good mechanical properties.
In order to ensure proper strength of antiadhesive interleaves made of multi-layer polyethylene films, the films are used, in which individual layers consist of polyethylene with different molecular weights. The individual layers of the multi-layer film are sometimes modified by adding other polymers, such as for example polypropylene(s), and various additives, such as plasticizers, dyes, pigments, antistatic agents, release agents, and the like.
In the rubber industry, spacers (antiadhesive interleaves) made of polyethylene films are disposable after a single use and as such the are post-production wastes, intended for disposal or recycling.
For a long time, there has been an unmet need for antiadhesive interleaves in form of knurled multi-layer polyethylene films having the overall lower weight, thickness, while preserving however, the strength and operation parameters of the currently used spacers. Numerous attempts to change the parameters of the antiadhesive interleaves by changing the material composition of the various layers of the multi-layer films, the thickness of the finished strips or other parameters of polyethylene films were not accepted by the manufacturers of rubber products, especially tires. The aim of the invention is to provide a multi-layer film of polyethylene antiadhesive interleaves for the rubber industry and not only capable of reducing weight polyethylene post- production wastes in the industry, but also to provide a process of manufacturing such a film, as well as the production line for carrying out the method.
These objectives are achieved by providing a solution according to the present invention.
A multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in form of a knurled strip, according to the invention is characterized in that it is made of a 1-9 layer polyolefin sleeve with the inner adhesive layer, subjected to blocking after being formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25-100 μιη and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation.
The multi-layer polyolefin film according to the invention has preferably the inner adhesive layer which is made of a mixture having a Vicat temperature below 70°C and consisting of:
a) EVA copolymers with a vinyl acetate content of more than 19%; or
b) acetate plastomers of density lower than 0.900 g/cm3; or
c) other polymers or copolymers exhibiting comparable blocking properties.
In the multi-layer polyolefin film according to the invention, the layers responsible for its mechanical properties are made of polymers and copolymers from the group of polyolefins having density of 0.900 g/cm3 - 965 g/cm3.
A variant of a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, according to the invention is characterized in that the strip is obtained by cutting a 1-9 layer polyolefin sleeve formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25-100 μιη and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation.
In this embodiment in the multi-layer polyolefin film according to the invention the layers responsible for its mechanical properties are made of polymers and copolymers from the group of polyolefins having density of 0.900 g/cm3 - 965 g/cm3.
The invention covers also a process for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, wherein streams of variety of different melted polyolefins are the co-extruded and subjected to blow molding to form a multi-layer polyolefin sleeve, and the resulting multi-layer strip is knurled at temperature above the softening points of the polyolefins used, which process according to the invention is characterized in that by blow molding a 1-9 layer polyolefin sleeve is formed by co- extrusion of different melted polyolefins, which sleeve is passed through nip rolls, and then subjected to unidirectional longitudinal orientation using a set of rollers of different temperatures and different speeds, till achieving at 70-120°C the film thickness reduction in the range of 2-7,5 times, from an initial value of 400-80 μιη, to a final value of 25-110 μιη, and the thus obtained uniaxially oriented film is subjected to knurling and it is packed according to customer's requirements.
In the manufacturing process according to the invention, preferably the composition of the manufactured multi-layer film is controlled gravimetrically and the automatic interoperational control of thickness of the manufactured multi-layer film is carried out.
Preferably, in the manufacturing process according to the invention polymers and copolymers from the group of polyolefins having density of 0.900 g/cm3 - 965 g/cm3 are used as a material for forming the layers responsible for the mechanical properties of the produced multilayer film.
According to the invention, for the internal staining pigments in the form of a master batch are used.
Preferably, in accordance with the invention the film sleeve is produced, wherein the inner adhesive layer is made of a mixture having a Vicat temperature below 70°C and consisting of:
a) EVA copolymers with a vinyl acetate content of more than 19%; or
b) acetate plastomers of density lower than 0.900 g/cm3; or
c) other polymers or copolymers exhibiting comparable blocking properties. and the obtained film sleeve is subjected to compression by the rolls heated to a temperature of 60-90°C and operating under the pressure in the range of 3-7.5 bar and in result of the thus conducted blocking - at the exit of the rolls, the film strip is produced.
In the manufacturing process according to the invention during the step of uniaxial longitudinal orientation of the formed film sleeve or the blocked film strip, the film is reheated to a temperature adjusted to the film composition, within the range of 70-120°C, by means of contacting the film with the heated rollers and then the thus heated film is directed to the heating rollers which rotate at different rotational speeds, and after reaching a reduction of thickness of the film in the range of from 1: 2 to 1: 7.5, the film is cooled from the temperature of orientation of the film to the ambient temperature.
In the manufacturing process according to the invention, after the step of uniaxial orientation in the longitudinal direction, the film is subjected to longitudinal edge cutting, and cut edges are recycled to the stage of the preparation of the blow molding mixture.
According to the invention, the central portion of the blocked film web obtained in result of the longitudinal edge cutting is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
Alternatively, in case of the multi-layer polyolefin film sleeve without the adhesive inner layer, the two independent film strips uniaxially oriented in the longitudinal direction, resulting form the longitudinal edge cutting are wound on two large bales using a two-reel winder, which bales are then - directly or at any time thereafter, individually transferred to a separate knurling station to an unwinder reel of the knurling station and the film strip is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
The present invention relates also to a technological line for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, as described above, comprising:
a) an apparatus for co-extrusion of different polyolefin melts and forming the multi-layer polyolefin sleeve by blow molding;
b) a system of nip rolls heated to a temperature of 60-90°C and operating under the pressure in the range of 3-7.5 bar;
c) an assembly for longitudinal orientation;
d) an assembly for longitudinal edge cutting of the blocked strip or a film sleeve; and e) an assembly for film knurling;
f) a winder which line is characterized in that between the system of nip rolls and the assembly for longitudinal edge cutting, there is an assembly for uniaxial longitudinal orientation comprising heating rollers which rotate at different rotational speeds and a system for cooling the film cooled from the temperature of orientation of the film to the ambient temperature.
The technological line according to the invention is also characterized in that the assembly for uniaxial longitudinal orientation is the MDO unit.
The technological line according to the invention preferably further comprises an assembly for gravimetric control of composition of the manufactured multi-layer film, as well as a device for automatic interoperation control of thickness of the manufactured multi-layer film.
In the technological line according to the invention, in agreement with the first variant of a process for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form multi-layer polyolefin sleeve without adhesive inner layer, downstream to the assembly for longitudinal edge cutting there is arranged a two-reel winder for winding two separate uniaxially longitudinally oriented film strips on the two large bales and the assembly for the film knurling forms a separate knurling station, which bales are then individually transferred to an unwinder reel of the knurling station and the film strip is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
The film according to the present invention, i.e. the film subjected to the uniaxial longitudinal orientation and having a thickness reduced 30-60% depending on the final destination, as compared with the polyolefin spacers currently used in the rubber industry, without loss of strength and other performance benefits.
The film according to the invention is knurled, and the resulting pattern is designed to reduce the contact surface between the film and the rubber compound.
In a variant of the production line according to the invention the sleeve of the multi-layer film without blocking is directed to the assembly for longitudinal orientation, and after the step of uniaxial orientation, the longitudinally oriented sleeve of multi-layer film is separated in step of longitudinal edge cutting into two strips of longitudinally oriented film, which strips separately are directed to the knurling operation step, either immediately after separation or after winding on two separate shafts. The resulting knurled uniaxially longitudinally oriented multi-layer film is packaged according to customer's requirements. Due to the longitudinal orientation the knurled multi-layer film of the invention exhibits:
■ an increased strength at break
■ anincreased yield point,
■ anincreased elongation at break.
and in the intended use as antiadhesive interleaves for rubber industry streamlines directing webs calendered rubber compound for further processing and reduces the degree of contamination of the rubber compound with scraps of plastic antiadhesive interleaves, as well as increases the reliability of the process.
At the same time, the longitudinally oriented antiadhesive interleaves of knurled multilayer film of the present invention are thinner than conventional ones, which significantly reduces the amount of post-production wastes. It also means a corresponding reduction in the load of equipment for storage and handling the bales of extruded rubber, thus helping to reduce wear and extend the life of the equipment.
The invention is described below in more detail with reference to the accompanying drawings, in which
Fig. 1 shows a block diagram of the method according to the invention,
Fig. 2 shows a production line A for the manufacturing of a knurled uniaxially longitudinally oriented blocked multi-layer film for use as antiadhesive interleaves for rubber industry, and
Fig. 3 shows a production line B for the production of knurled uniaxially longitudinally oriented multi layered film for use as antiadhesive interleaves for rubber industry.
Detailed description of the invention.
According to Fig. 1 in the present invention there are carried out three main processes: extrusion of a film, uniaxial longitudinal orientation and knurling of the uniaxially longitudinally oriented film. The method further includes the auxiliary processes: gravimetric control of the composition of the produced film, and automatic interoperational control of the thickness of the film. The method may be implemented in two versions: a continuous production process (Line A, as shown in Fig. 2) or process with technological break before knurling operation (Line B shown in Fig. 3).
The method of the present invention is adapted to the technological requirements associated with the use of a multi-layer polyolefin film in the form of a sleeve r2, with the adhesive inner layer (Fig. 2) that is subjected to blocking on the pulling nip rollers 3 that exert pressure to form a single strip of the multi-layer film. The production line used in this embodiment of the present invention is composed of an extruder 1, a head 2 for blowing of the extruded film to form a film sleeve rl_, the nip rollers 3, passing through which results in obtaining a single strip of the multi-layer film fz being directed to a MDO device 4 for effecting the uniaxial longitudinal orientation, and then the longitudinally oriented film fo is directed to the knurling assembly 5 integrated into the production line A. The knurled longitudinally oriented film mfo is received on a winder 6. Sections of the knurled longitudinally oriented film - according to the customer orders, are wound on separate bobbins. The advantage of this variant is producing the final knurled multi-layer film in a single production cycle.
In other embodiment of the process for manufacturing of the sleeve r2 of the multi-layer polyethylene film, without adhesive inner layer, the line B shown in Fig. 3 is used for production, the line comprising an extruder 1, a head 2 for blowing the extruded film to form a film sleeve r2, the sleeve being unsusceptible to blocking, the nip rollers 3, passing through which results in obtaining a compressed sleeve of multi-layer film f in a form of strip, further directed to the MDO device 4 to undergo an uniaxial longitudinal orientation, and the longitudinally oriented film fo - after the operation of longitudinal edge cutting is in form of two separate strips of longitudinally oriented film fo which are directed to the two-reel winder 7a, 7b. After a technological break, each strip - obtained from the sleeve r2 by longitudinal edge cutting and after the step of uniaxial longitudinal orientation in the M DO device 4, wound on separate big bale on the two-reel winder 7a, 7b, is transferred to the rewinder 8 of the knurling assembly 5, where this uniaxially oriented film is subjected to a longitudinally knurling, at the softening temperature, being afterwards cooled and packaged using a winder 6, in accordance with the customer's needs.
Additionally, in this embodiment, between the process of orientation using an M DO device 4 and the knurling step - in the knurling assembly 5, an operation of manual controlling of the film thickness is carried out.
A ready for dispatching knurled film according to the invention for use as antiadhesive interleaves (spacers) for the rubber industry, produced in accordance with the process according to the invention using the production lines A and B as shown in Fig. 2 and Fig. 3 is identical and has the same performance characteristics, irrespectively of the production variant.
The present invention provides process for manufacturing a knurled multi-layer polyolefin film according to the invention, for use as antiadhesive interleaves for the rubber industry. According to this process streams of different melts of polyolefins, preferably polyethylene, sometimes modified with other polymers or other additives and ingredients of refining character are co-extruded and then subjected to blow molding to form a multi-layer film sleeve, which is passed through the pulling assembly of nip rollers.
In the embodiment of the present process performed while using a technological line A according to the invention, as illustrated in Fig. 2, a multi-layer, including 1-9 layers, polyethylene film is obtained by using a device for the production of films by blow molding comprising the extruder 1 having a head 2, wherein the inner layer of the sleeve rl_ comprises very adhesive components, which are strongly susceptible to blocking, such as for example the acetate plastomer having a density less than 0.900 gm/cm3, EVA copolymers with a vinyl acetate content greater than 19% or lots more of the like materials. The materials susceptible to blocking should have a Vicat temperature below 70°C. The film sleeve, of which the inner layer has an adhesive component is squeezed by the pulling nip rolls 3 heated up to a temperature in the range 60-90°C and pressed with a pressure within the range of 3.0-7.5 bar, which results in blocking. In this way, after leaving the rolls 3 a single multi-layer strip fz - not the sleeve, is obtained.
The thus blocked strip is submitted to longitudinal orientation. This process is carried out in the device 4 called MDO. This process involves reheating the film. The process of heating the film strip is carried out by contacting the material with the rollers, which are of suitable temperatures. Depending on the composition of the film rollers are heated to a temperature comprised between 70-120°C
The thus heated film is passed in the device 4 to the next heating rollers rotating at different circumferential speed. Roller speed differences affect the rate of longitudinal orientation. The degree of orientation ranges from 1: 2 to 1: 7.5 depending on the desired final parameters of the film.
After the step of uniaxial longitudinal orientation in the MDO device 4 the film fo is subjected to longitudinal edge cutting, i.e. the left and right side uneven edges of the tape are cut off, the cut material is recycled to step the preparation of melt for blow molding, and the central (middle) portion of the strip is subjected to heating by a number of heating rolls and infrared radiators, and then - when film is heated above the softening temperature, it is subjected to knurling operation, providing the knurled pattern according to the customer's order using the knurling assembly 5.
The resulting knurled film mfo is wound round bales of a winder 6, adjusting the amount of current meters of film on each bale to request of the customer, and then the bales are packed on pallets. At each step, the quality control in terms of uniformity, absence of air bubbles and mechanical damage is carried out.
The thickness of the multi-layer film is controlled automatically at various stages of manufacturing process.
An exemplary the raw material composition of the multi-layer film subjected to blocking as referred to above is given below in Table 1.
Table 1. The raw material composition of the strip fz of multi-layer film subjected to blocking
The composition of the coextruded individual layers of the multi-layer film
Figure imgf000011_0001
Meaning of symbols used:
FX1001 - LDPE - is responsible for the mechanical parameters,
FL00226 - copolymer EVA - It has good adhesive properties,
1018 KB - m LLDPE - linear metallocene used to improve the weldability,
M 65 - antiblock - improves the geometry of the roll,
RA 295 - antiadhesive additive - reduces the adhesion of the rubber compound to the film,
VLA 55 - antistatic additive - eliminates static electricity,
Green 3011 - green dye.
Using the production line B according to the invention shown in Fig. 3, another embodiment of the invention can be realized, with the only difference being that the multi-layer film sleeve r2 is not blocked after the leaving the blow molding installation. The formed film is automatically twice as thick as in the previous embodiment.
Raw material compositions of the individual layers A, B, C and D are the same as in the above described embodiment, while instead of the layer E forming in the above embodiment the inner layer, layer A is repeated. An exemplary raw material compositions of strip f that is not to be subjected to blocking, as referred to above, are given in the Table 2 below. The meaning of the symbols used therein, is the same as described above with reference to Table 1.
Table 2. Raw material composition of the multi-layer film strips that were not to be subjected to blocking
Figure imgf000012_0001
In this embodiment of the invention, the film enters the MDO device 4 in the form of a sleeve r2 and after the longitudinal edge cutting operation the sleeve is split into two separate longitudinally uniaxially oriented multi-layer film strips fo. In addition, the knurling assembly 5 is not an integral part of the technological line B of the present invention, but is a separate knurling station, including rewinder 8, the knurling device 5 and winder 6 to wind the film.
Also in the present embodiment, a multi-layered film is obtained by using a line for the production of films by blow molding. The outer and inner layers of the sleeve have the same composition as the outer layer in the first embodiment of the invention, i.e. the sleeve r2 has no internal adhesive layer to enable blocking.
The temperature of the pulling nip rolls 3 is ca. 56°C, and the pressure is up to 5 bar.
The film behaves according to standards, i.e. after passing through the pulling nip rolls 3 it has the form of a strip retaining the original form of a sleeve r2, and as such is directed on to the MDO device 4, while after longitudinal edge cutting operation it splits into two separate strips fo which are wound by the two-reel winder 7a, 7b on large bales. Next, the so called jumbo rolls are transported to an unrolling device 8 of the knurling assembly 5 organized as a separate station.
The knurling process and temperature parameters thereof are the same as in the first embodiment of the invention. The invention is further illustrated by the following examples, which specifically describes a process for manufacturing a knurled multi-layer polyethylene film for use as antiadhesive interleaves, in particular for the rubber industry. Comparative examples allow to assess the advantages of the inventive film.
Example. To the production plant Hosokawa Alpine five-layer system with additional longitudinal orientation MDO produces sleeve multi-layer blow molding method has been dosed PE granulate with the composition given above in Tables 1 and 2.
An apparatus for forming films by blowing LDPE material was supplied, which was processed at a temperature of 180-230°C. During the blowing sleeve was cooled with the air stream and reached a temperature in the range of 40-80°C prior to being directing the pulling (stretching) nip rollers.
In operation according to the aforementioned first embodiment of the present invention produced a complex multi-layer film (with blocking) at 60-90°C.
In operation according to the above second embodiment of the invention, a multi-layer film was produced in the form of a sleeve, keeping the pinch rollers compression temperature to 56°C.
Orienting the longitudinal webs formed of PE was conducted in both embodiments, the orientation of which has a value of 6.0 at a temperature of 103°C.
As a result of the MDO orientation process obtained in the first embodiment of the invention a single web of pre-stretched multi-layer film, which is directed to the longitudinal edge cutting rollers heated to 95°C and then heated infrared radiators to a temperature above the softening temperature. The heated film was directed to the knurling shafts where the pattern was extruded and then the knurled film was cooled and wound into a roll.
As a result of the orientation of the MDO process, in the second embodiment of the invention, the pre-stretched multi-layer film sleeve was obtained, which sleeve after cooling down and longitudinal edge cutting has been split into two separate multi-layer film strips which were wound onto a separate rolls. During the next stage, carried out on another device, resulting oriented multi-layer film has undergone a process knurling.
Samples of the film obtained under the first or second embodiment was subjected to the following quality tests: strength, tensile strength, elongation at break.
As a comparative material the film available on the market with the symbol FT MOLET 100 microns LDPE was used n. The film was produced on a commercial production line of film blow molding method. The comparative film was a three-layer film. This material was made from a mixture of: LDPE + M DPE + systemic additives. Comparative film had a thickness of 100 microns and had embossed pattern identical to the film manufactured in accordance with the present invention. The results are summarized in Table 3
Table 3. Measurement results of comparative strength of the film obtained in accordance with various embodiments of the invention and a commercial film
Figure imgf000014_0001
The results confirm the compliance the above described film parameters of the invention with the parameters of the currently used anti-adhesive inserts, i.e. The breaking strength. With a 35% reduction in thickness the film according to the present invention appears to maintain (or even exceed) the strength parameters.
Summary presented in Table 3 shows that the strength properties of the film produced in accordance with the first and second embodiment of the present invention are identical.
The invention has been described in detail with reference to the polyolefin film produced in the form of a sleeve by blow molding. The same inventive concept can be successfully used in the production of multi-layer films of the knurled-layer film obtained by casting.
In addition, in the second embodiment of the invention it is possible to control one of the two distinct longitudinally uniaxially oriented multi-layer strips to the knurling device integrated into the production line, the second winding shaft - for later transfer to separate knurling device representing a separate processing station.

Claims

Claims
2. A multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in form of a knurled strip, characterized in that it is made of a 1-9 layer polyolefin sleeve with the inner adhesive layer, subjected to blocking after being formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25-100 μιη and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation.
3. The multi-layer polyolefin film according to claim 1, characterized in that the inner adhesive layer is made of a mixture having a Vicat temperature below 70°C and consisting of:
a) EVA copolymers with a vinyl acetate content of more than 19%; or
b) acetate plastomers of density lower than 0.900 g/cm3; or
c) other polymers or copolymers exhibiting comparable blocking properties.
4. The multi-layer polyolefin film according to claim 1, characterized in that the layers responsible for its mechanical properties are made of polymers and copolymers from the group of polyolefins having density of 0.900 g/cm3 - 965 g/cm3.
5. A multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, characterized in that the strip is obtained by cutting a 1-9 layer polyolefin sleeve formed by blow molding, uniaxially oriented in the longitudinal direction at temperature 70-120°C, of a thickness reduced in the range of 2-7,5 times to a final value of 25- 100 μιη and knurled at a temperature above its softening point, after the prior uniaxial longitudinal orientation.
6. The multi-layer polyolefin film according to claim 4, characterized in that the layers responsible for its mechanical properties are made of polymers and copolymers from the group of polyolefins having density of 0.900 g/cm3 - 965 g/cm3.
7. A process for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, wherein streams of variety of different melted polyolefins are the co-extruded and subjected to blow molding to form a multi-layer polyolefin sleeve, and the resulting multi-layer strip is knurled at temperature above the softening points of the polyolefins used, characterized in that by blow molding a 1-9 layer polyolefin sleeve is formed by co-extrusion of different melted polyolefins, which sleeve is passed through nip rolls, and then subjected to unidirectional longitudinal orientation using a set of rollers of different temperatures and different speeds, till achieving at 70-120°C the film thickness reduction in the range of 2-7,5 times, from an initial value of 400-80 μιη, to a final value of 25-110 μιη, and the thus obtained uniaxially oriented film is subjected to knurling and it is packed according to customer's requirements.
8. The manufacturing process according to claim 6, characterized in that the composition of the manufactured multi-layer film is controlled gravimetrically.
9. The manufacturing process according to claim 6 or 7, characterized in that the automatic interoperational control of thickness of the manufactured multi-layer film is carried out.
10. The manufacturing process according to any one of claims 6 to 8, characterized in that polymers and copolymers from the group of polyolefins having density of 0.900 g/cm3 - 965 g/cm3 are used as a material for forming the layers responsible for the mechanical properties of the produced multi-layer film.
11. The manufacturing process according to any one of claims 6 to 9, characterized in that for the internal staining pigments in the form of a master batch are used.
12. The manufacturing process according to any one of claims 6 to 10, characterized in that the film sleeve is produced, wherein the inner adhesive layer is made of a mixture having a Vicat temperature below 70°C and consisting of: a) EVA copolymers with a vinyl acetate content of more than 19%; or
b) acetate plastomers of density lower than 0.900 g/cm3; or
c) other polymers or copolymers exhibiting comparable blocking properties.
12. The manufacturing process according to claim 11, characterized in that the obtained film sleeve is subjected to compression by the rolls heated to a temperature of 60-90°C and operating under the pressure in the range of 3-7.5 bar and in result of the thus conducted blocking - at the exit of the rolls, the film strip is produced.
13. The manufacturing process according to any one of claims 6 to 10 or 12, characterized in that during the step of uniaxial longitudinal orientation of the formed film sleeve or the blocked film strip, the film is reheated to a temperature adjusted to the film composition, within the range of 70-120°C, by means of contacting the film with the heated rollers and then the thus heated film is directed to the heating rollers which rotate at different rotational speeds, and after reaching a reduction of thickness of the film in the range of from 1: 2 to 1: 7.5, the film is cooled from the temperature of orientation of the film to the ambient temperature.
14. The manufacturing process according to claim 13, characterized in that after the step of uniaxial orientation in the longitudinal direction, the film is subjected to longitudinal edge cutting, and cut edges are recycled to the stage of the preparation of the blow molding mixture.
15. The manufacturing process according to claim 14, characterized in that the central portion of the blocked film web obtained in result of the longitudinal edge cutting is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
16. The manufacturing process according to claim 14, characterized in that in case of the multilayer polyolefin film sleeve without the adhesive inner layer, the two independent film strips uniaxially oriented in the longitudinal direction, resulting form the longitudinal edge cutting are wound on two large bales using a two-reel winder, which bales are then - directly or at any time thereafter, individually transferred to a separate knurling station to an unwinder reel of the knurling station and the film strip is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
17. A technological line for manufacturing a multi-layer polyolefin film for use as antiadhesive interleaves for the rubber industry, in the form of a knurled strip, as described in the claim 1 or 4, comprising:
a) an apparatus for co-extrusion of different polyolefin melts and forming the multi-layer polyolefin sleeve by blow molding;
b) a system of nip rolls heated to a temperature of 60-90°C and operating under the pressure in the range of 3-7.5 bar;
c) an assembly for longitudinal edge cutting of the blocked strip or a film sleeve; and d) an assembly for film knurling,
characterized in that between the system of nip rolls and the assembly for longitudinal edge cutting, there is an assembly for uniaxial longitudinal orientation comprising heating rollers which rotate at different rotational speeds and a system for cooling the film cooled from the temperature of orientation of the film to the ambient temperature.
18. The technological line according to claim 17, characterized in that the assembly for uniaxial longitudinal orientation is the MDO unit.
19. The technological line according to claim 17, characterized in that it further comprises an assembly for gravimetric control of composition of the manufactured multi-layer film.
20. The technological line according to claim 17, characterized in that it further comprises a device for automatic interoperation control of thickness of the manufactured multi-layer film.
21. The technological line according to any one of claims 17 to 20, characterized in that in the case of manufacturing a multi-layer polyolefin sleeve without adhesive inner layer, down-stream to the assembly for longitudinal edge cutting there is arranged a two-reel winder for winding two separate uniaxially longitudinally oriented film strips on the two large bales and the assembly for the film knurling forms a separate knurling station, which bales are then individually transferred to an unwinder reel of the knurling station and the film strip is reheated by a number of heated rolls and infrared heaters up to a softening temperature and then subjected to knurling to form knurled pattern according to the customer's request and the resulting knurled film is wound on bales using a winder and adjusting the number of current meters of the film on each bale to the customer's order.
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CN113432941A (en) * 2021-05-25 2021-09-24 天津大学 Soil sample membrane loading device for soil-driven triaxial test
CN113432941B (en) * 2021-05-25 2022-07-05 天津大学 Soil sample membrane loading device for soil-driven triaxial test

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