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WO2017077555A1 - Process for producing cross laminated polymer film - Google Patents

Process for producing cross laminated polymer film Download PDF

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Publication number
WO2017077555A1
WO2017077555A1 PCT/IN2016/050384 IN2016050384W WO2017077555A1 WO 2017077555 A1 WO2017077555 A1 WO 2017077555A1 IN 2016050384 W IN2016050384 W IN 2016050384W WO 2017077555 A1 WO2017077555 A1 WO 2017077555A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
cross
films
range
grooved
Prior art date
Application number
PCT/IN2016/050384
Other languages
French (fr)
Inventor
Eldhose Kavanachuvattil PETER
Ammapuram Rajaraman RAJESH
Original Assignee
Srf Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Srf Limited filed Critical Srf Limited
Publication of WO2017077555A1 publication Critical patent/WO2017077555A1/en

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    • 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
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/10—Interconnection of layers at least one layer having inter-reactive properties
    • 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
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    • 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
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
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    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/22—Layered products comprising a layer of synthetic resin characterised by the use of special additives using plasticisers
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
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    • 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
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    • B32B37/0046—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by constructional aspects of the apparatus
    • B32B37/0053—Constructional details of laminating machines comprising rollers; Constructional features of the rollers
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    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/144—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers using layers with different mechanical or chemical conditions or properties, e.g. layers with different thermal shrinkage, layers under tension during bonding
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    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/16—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with all layers existing as coherent layers before laminating
    • B32B37/20—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with all layers existing as coherent layers before laminating involving the assembly of continuous webs only
    • B32B37/203—One or more of the layers being plastic
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    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/0004—Cutting, tearing or severing, e.g. bursting; Cutter details
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    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/06—Embossing
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    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/03—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers with respect to the orientation of features
    • 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
    • B32B2250/03—3 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
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B32B2250/242—All polymers belonging to those covered by group B32B27/32
    • 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
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/402—Coloured
    • B32B2307/4026—Coloured within the layer by addition of a colorant, e.g. pigments, dyes
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • 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
    • B32B2307/538—Roughness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
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    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B2307/70—Other properties
    • B32B2307/726—Permeability to liquids, absorption
    • B32B2307/7265—Non-permeable
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
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    • B32B2553/00—Packaging equipment or accessories not otherwise provided for

Definitions

  • the present invention relates to the field of crosslaminates having a plurality of multilayer films of thermoplastic polymer material which are oriented in such a way that the orientation of the one film crosses the orientation of the other film.
  • the present invention relates to a process for producing a cross laminated polymer film having a plurality of multilayer films cross sandwiched with one another in opposite direction.
  • the cross laminate film of the present invention has a good tear propagation resistance, good tensile strength and good lamination strength.
  • cross laminates polymer materials have been commercially produced since 1968 and find extensive use in waterproofing, roof underlayment, air/vapor barrier, industrial bags, cover sheets, packaging materials, tarpaulins etc. It is known in the art that the film made from cross lamination is extremely strong yet light weight, flexible and tougher than any other plastic film of comparable weight and thickness.
  • the polymer compositions of film, which have been industrially used in cross laminates, is mainly based on HDPE, LLDPE (and blends of the two) or crystalline PP.
  • the process of producing crosslaminates usually comprises making multilayered blown film keeping the molecular orientation in the direction of machine operation, spiral cutting the film to the machine direction with a specific angle and laminating together the layers of the spiral cut films, with orientations at opposite angles.
  • the cross- laminated film usually goes through a stretching process in different directions, so that the molecules of the final product are isotropically oriented.
  • Such process of cross lamination highly enhances the tensile strength of the film by modifying the molecular arrangement and physical structure of the blown films.
  • crosslaminates made from similar polymers exhibit improved tear propagation resistance compared to a simply biaxially oriented film.
  • US 7,976,925 describes a process for preparation of cross laminate polymer whereby cross laminate is formed from tubular films formed by co-extrusion and helically cutting of the films followed by cross sandwiching in opposite direction followed by lamination.
  • the intent of this invention was to provide an improved and simplified strong bond/ weak bond system for the cross laminate by use of extrusion and/ or provide it with improved aesthetics.
  • This invention mainly concerns having modification of the surface properties of the two films in a suitable pattern in such a way that the internally arranged surfaces of the films comprise an array of strands of co- extruded material and the array of strands of two films cross one another.
  • Indian patent application 1432/CHENP/2011 discloses a method and apparatus for manufacture of a polymer film, which is oriented under an angle to its longitudinal direction.
  • the manufacture of an oriented film for cross-lamination requires stabilization of the orientation prior to the lamination to reduce the internal tensions which build up when films are stored on reel. Therefore, this invention mainly concerns reduction in such stabilization problems by carrying out the stretching in the tumbling unwinder, which is used in connection with the helical cutting, to ensure stabilization of the films after the helical cutting.
  • the processes known in the art show that the modification of various steps of the producing a crosslaminate improve the properties of the final product. It is observed that most the research in the art is based on the significance of longitudinal stretching, segmental stretching, semi-fibrillation, etc. to obtain a cross laminate with desired tear propagation resistance and improved tensile strength. However, such processes are time consuming and require additional equipment resulting in huge processing costs to obtain the final product.
  • the main purpose of the present invention is to reduce such processing costs using simple production steps in the manufacture of cross laminates without compromising the desired properties of the cross laminated polymer films.
  • the present invention relates to a process for producing a cross laminated polymer film.
  • a process for producing a cross laminated polymer film Particularly, cross-laminates having a plurality of multilayer films of thermoplastic polymer material are produced in the present invention in which the orientation of the one film crosses the orientation of the other film.
  • the present invention produces a cross laminated polymer film having a good tear propagation resistance, good tensile strength and good lamination strength using simplified process steps thereby providing economic advantage compared to the processes known in the art.
  • the present invention provides a process for producing cross laminated polymer film comprising the steps of:
  • tubular blown film comprises a thermoplastic polymer.
  • thermoplastic polymer is selected from the group consisting of HDPE, LLDPE, mLLDPE, LDPE and a combination thereof.
  • tubular blown film optionally comprises polyolefin plastomers in the range of 0-10 wt %.
  • the tubular blown film further comprises a color master batch in the range of 1-5%, UV stabilizers in the range of 1- 5% and additives in the range of 0.5 - 2 % .
  • tubular blown films have thickness in the range of 20-100 microns.
  • the laminating the cross sandwiched and grooved film comprising passing the cross sandwiched and grooved single layer of film through grooved roller and smooth rubber roller to obtain cross laminated polymer film; said cross sandwiched and grooved single layer of film is heated at a temperature in the range of 80 °C - 120°C using a plurality of preheated drums ;
  • the smooth roller having hardness in the range of 40 - 80 A.
  • the present invention provides a cross laminated polymer film comprising three co-extruded tubular blown films wherein the direction of orientation of each blown film crosses the direction of orientation of the neighboring film; said cross laminated polymer film is prepared by the process comprising the steps of:
  • tubular blown film comprising: a) middle layer comprising HDPE, LLDPE, mLLDPE,LDPE or a combination thereof and the middle layer is in the range of 40 -80 wt % of total film;
  • outer layer comprising LLDPE, mLLDPE,LDPE or a combination thereof and theouter layer is in the range of 10 -30 wt % of total film;
  • inner layer comprising LLDPE, mLLDPE ,LDPE or a combination thereof and the inner layer is in the range of 10 -30 wt % of total film;
  • the inner layer and outer layer optionally comprises polyolefin plastomer in the range of 0-10 wt % of total film .
  • the tubular blown film comprises color master batch in the range of 1-5%, UV stabilizers in the range of 1-5% and polymer process additives in the range of 0.5 - 2 % or a combination thereof.
  • the blown films is having thickness in the range of 20-100 microns.
  • the simultaneously cross sandwiching and grooving of three oriented flat films comprising the steps of: a) placing three helically cut blown films in such a way that the direction of orientation of one film crosses the direction of orientation of neighboring film and converging the three films together to obtain a single layer of film;
  • the laminating the cross sandwiched and grooved film comprising passing the cross sandwiched and grooved single layer of film through grooved roller and smooth rubber roller to obtain cross laminated polymer film; said cross sandwiched and grooved single layer of film is heated at a temperature in the range of 80 °C - 120°C using a plurality of preheated drums;
  • the smooth roller are having hardness in the range of 40 - 80 A.
  • the laminated film has crest and valley pattern.
  • the cross laminated polymer film is having pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm.
  • the crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer film.
  • the weight of the cross laminated polymer film is in the range of 50 - 300 gsm.
  • Fig. 1 shows the schematic presentation of the film orientation (A) before helical cutting and (B) after 45 degree helical cutting.
  • Fig. 2 shows schematic presentation of layered arrangement with orientation of the films.
  • Fig. 3 shows the schematic diagram of simultaneous cross sandwiching and grooving process.
  • 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating drums, 7A is rubber roller, 8 is grooved roller and 9 is winder.
  • Fig. 4 shows the schematic diagram of lamination of cross sandwiched and grooved film.
  • 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating drums, 7B is rubber roller, 8 is grooved roller and 9 is winder.
  • Fig. 5 A shows the straight grooved roller design having and valley structure having groove depth in the range of 0.2-2mm, groove width in the range of 0.2-2mm and pitch in the range of 0.6-4mm.
  • 5 B shows square grooved roller design having groove depth in the range of 0.2-5 mm, groove width in the range of 0.2-5 mm and square groove pattern in the range of lxl mm to 20x20mm.
  • 5 C shows diamond grooved roller design having groove depth in the range of 0.2-5 mm, groove width in the range of 0.2-5 mm and square groove pattern in the range of lxl mm to 20x20mm.
  • Fig. 6 shows the schematic diagram of individual grooving of helically cut films.
  • 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating driums, 7A is rubber roller, 8 is grooved roller and 9 is winder.
  • Fig. 7 shows the schematic diagram of lamination of individually grooved films.
  • 1 , 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating driums, 7B is rubber roller, 8 is grooved roller and 9 is winder.
  • Fig. 8 shows the schematic diagram of cross sandwiching, grooving and lamination in single line.
  • 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5, 6, 7 and 8 are heating drums, 9 A and 9B are rubber roller, 10A and 10 B are grooved roller and 11 is winder.
  • the present invention relates to the field of cross-laminates having at least two multilayer films of thermoplastic polymer material which are oriented in such a way that the orientation of one film crosses orientation of the other film.
  • the present invention relates to a process for producing a cross laminated polymer film having at least two films cross sandwiched with one another in opposite direction.
  • the cross laminate film of the present invention has a good tear propagation resistance ,good tensile strength and good lamination strength.
  • the present invention relates to development of a process for producing cross laminated polymer film comprising the steps of:
  • thermoplastic polymer material with the following compositions:
  • Middle layer 40 -80 % of total film with polymers selected from HDPE,LLDPE,mLLDPE,LDPE or combination of any two or all three.
  • Outer Layer 10 -30 % of total film with polymers selected from LLDPE or mLLDPE or LDPE or combination thereof with 0 -10 % polyolefin plastomers
  • the objective of helical cutting is to unfold a tubular film obtained in step (a) to a flat film with a change in orientation of molecules.
  • the helical cutting process is carried out by unwinding tubular blown film from a reel in an unwinding stand which performs a tumbling movement.
  • the purpose of tumbling movement is to rotate the lay - flat film around its longitudinally extending middle line.
  • the lay flat tube is inflated using air which is blown from the back side of the mandrel.
  • the mandrel provides a solid support for the inflated film.
  • the cutting taking place using a knife located in a fixed position at an angle of 25 to 75 degrees and the helically cut film is pulled away from the mandrel to the winder.
  • tubular blown films 1 , 2 and 3 are helically cut as explained in step (b) above and unfolded to flat films with change in orientation of molecules of films as shown in figure 2 and the films are termed as Helically cut films 1, 2 and 3, respectively (figure 2).
  • Helically cut films 1, 2 and 3 respectively (figure 2).
  • These helically cut films are placed in such a way that their orientations are at opposite direction i.e. the orientation criss - cross each other and the lamination layer of each film are in contact with each other.
  • the helically cut films 1, 2 and 3 are placed in the let off rollers 1, 2 and 3 (rendered flat as explained above in step (b)) in such a way that when sandwiched to form a single layer, their orientations are opposite to each other and lamination layer in each film is in contact with each other.
  • These 3 films are converged together using series of idle rollers (4) at temperature in the range of 25 -40°C. There is no lamination between the films at this stage as the process is done at room temperature.
  • the converged film as shown in figure 3 follows first preheating drum (5) set at 60-100 °C followed by second heating drum (6) set at 70-110 °C. The converged film follows the path in such a way that both sides of the film get heated.
  • preheating each film individually at a temperature in the range of 80-120 C before converging the films together;
  • the heated film is then sandwiched using grooved steel roller (8) (having straight groove pattern) and smooth rubber roller (7 A) having hardness 40 - 80 A to obtain the cross-laminate film with pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm. and the crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer film. Since the temperature of the second drum (6) is lower than the melting point (lower by at least 10 degree) of the lamination layer, the sandwiched film will not be strongly laminated.
  • the film will soften and grooving using grooved roller and rubber roller results in weak lamination over the entire film. This will also introduce a grooving pattern i.e. crest and valley over the sandwiched film.
  • the film passes through a series of idling (4) transfer rollers as shown in figure 3.
  • the downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 0 - 25 % stretching in machine direction and helps to make the grooving pattern even.
  • the simultaneously cross sandwiched and grooved has very low lamination between the plies and can be easily delaminated by repeated flexing and rubbing by hand.
  • Different grooved roller patterns like square groove, diamond groove patterns can be used to create different design pattern on final film as shown in fig 5.
  • the cross sandwiched and grooved film passes first preheating drum (5) set at 70-110 °C followed by second heating drum (6) set at 80 -120 °C.
  • the film follows the path in such a way that both sides of the film get heated.
  • the heated film is then laminated using same grooved steel roller (8) and smooth rubber roller (7 B) of hardness 40-80 A.
  • the cross sandwiched and grooved film can be directly heated and laminated using single heating drum set at higher temperature in the range of 110 - 135 C. In that case preheating is not required. Since the temperature of the second drum is very close to the melting temperature of the lamination layer, the sandwiched film will be heat sealed.
  • the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite.
  • the lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film.
  • the film passes the idling transfer roller (4).
  • the downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 0 - 25 % stretching in machine direction. This helps to make the grooving pattern even.
  • the cross sandwiched and grooved film from the transfer roller (4) is then wound up on a roller (9) with winding tension as low as possible to allow shrinkage.
  • the final cross laminate film obtained is in the range of 50 - 300 gsm.
  • the cross laminate film obtained in step (d) has crest and valley pattern with pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm. and the crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer.
  • Overall the laminated cross laminate film of the present invention has good lamination strength and cannot be delaminated by repeated flexing and rubbing by hand.
  • cross sandwiching, grooving and lamination can also be performed in a single line as per the drawing 8.
  • Film 2 Middle layer - 70 % of total comprising HDPE of MFI - 0.3 and density - 0.944 g/ml, Outer Surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
  • Film 3 Middle layer - 70 % of total comprising HDPE of MFI - 0.3 and density - 0.944 g/ml, Outer Surface layer - 10 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 20 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
  • Blown up Ratio used was 2.5: 1 and Longitudinal draw down ratio used wasl6: l.
  • Color master batch (4 %), UV stabilizers (3 %) and additive (0.75 %) were blended with each layer.
  • the thickness of films 1, 2 and 3 was 55 Micrometer. Difference in modulus of Elasticity of films used in the product is less than 15 % and are given below
  • the tubular films were helically cut at an angle of 45°.
  • the helically cut films 1, 2 and 3 each are placed in the let off rollers 1 , 2 and 3 and these 3 films are converged together using idle rollers (4) at 30°C in such a way that their orientations are opposite to each other during sandwiching and lamination layer in each of the films 1, 2, 3 are in contact with each other.
  • the converged film follows first preheating drum (5) set at 90°C followed by second heating drum (6) set at 100°C.
  • the converged film follows the path in such a way that both sides of the film get heated.
  • lamination of Cross Sandwiched and grooved film using grooved roller is carried out.
  • the cross sandwiched and grooved film passes first preheating drum 1 (5) set at 100 °C followed by second heating drum ( 6) set at 112°C.
  • the film follows the path in such a way that both sides of the film get heated.
  • the heated film is then laminated using same grooved steel roller (8) and smooth rubber roller (7 B) of hardness 70 A. Since the temperature of the second drum is very close to the melting temperature of the lamination layer, the sandwiched film will be heat sealed. However, the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite.
  • the lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film. After lamination the film which helps to make the grooving pattern even.
  • the film then wound up on a roller with winding tension as low as possible to allow shrinkage.
  • the final cross laminate film obtained has 150 gsm.
  • the process of the present invention has also been compared with individual grooving process where the helically cut films were individually grooved first using grooved roller followed by the lamination of individually grooved films.
  • the co-extruded multilayered tubular blown films and helical cutting was carried out similar to example 1.
  • the process of example 2 is carried out like example 1 except for grooving process which takes place individually as shown in figure 5 and lamination is carried out as shown in figure 6.
  • the helically cut film 1 passes through first heating drum ( 5) set at 90 °C and second heating drum ( 6) set at 100 °C.
  • the heated film is then grooved using grooved steel roller (8) and smooth rubber roller (7 A). This will also introduce a grooving pattern i.e. crest and valley over the film.
  • the film then passes the idling (4) transfer roller.
  • the downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction. This helps to make the grooving pattern even.
  • the film then wound up on a roller (9) with winding tension as low as possible to allow shrinkage. The same process is repeated for helically cut films 2 and 3 to introduce the grooving pattern.
  • the grooved film Since the temperature of the second drum is very close to the melting temperature of the lamination layer, the grooved film will be heat sealed. However the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite.
  • the lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film. After lamination the film passes the idling transfer roller. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction. This helps to make the grooving pattern even.
  • the film then wound up on a roller with winding tension as low as possible to allow shrinkage. The final gsm of the product obtained is 150 gsm.
  • Example 3 Comparision Between Process And Product Of Example 1 And Example 2
  • Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
  • Blown up Ratio used was 2.5: 1 and Longitudinal draw down ratio used wasl6: l.
  • Color master batch, UV stabilizers and polymer process additives were blended with each layer.
  • Film thickness of films 1, 2 and 3 was 54 Micrometer. Difference in modulus of Elasticity of films used in the product is less than 15 % and are given below
  • the sandwiched film will not be strongly laminated.
  • the film will soften and grooving using grooved roller and rubber roller results weak lamination over the entire film. This will also introduce a grooving pattern i.e. crest and valley over the sandwiched film.
  • the film passes the series of idling (4) transfer rollers. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction which helps to make the grooving pattern even.
  • the film is then wound up on a roller (9) with winding tension as low as possible to allow shrinkage.
  • the cross sandwiched and grooved film has very low lamination between the plies and can be easily delaminated by repeated flexing and rubbing by hand. However the laminate at this stage doesn't delaminate during the next process i.e. final lamination.
  • lamination of Cross Sandwiched and grooved film using grooved roller is carried out.
  • the cross sandwiched and grooved film passes the heating drum set at 127 °C.
  • the heated film is then laminated using same grooved steel roller (8) and smooth rubber roller (7 B) of hardness 70 A. Since the temperature of the heating drum is very close to the melting temperature of the lamination layer, the sandwiched film will be heat sealed. However, the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite.
  • the lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film.
  • the film then wound up on a roller with winding tension as low as possible to allow shrinkage.
  • the final cross laminate film obtained has 150 gsm.
  • the lamination layer in individual film comprises 5 % polyolefin plastomer to improve the lamination strength between the films.
  • Film 1 Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 38.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 8.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising LLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer ( 5%) of MFI - 1.0 and density 0.904 g/ml
  • Film 2 Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer ( 5%) of MFI - 1.0 and density 0.904 g/ml, Inner surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer (5%) of MFI - 1.0 and density 0.904g/ml
  • cross laminated film produced by process 1 of the present invention have also been compared with a well-known commercially available cross laminated film product of the same gsm - 150gsm.
  • Table 9 shows the comparative properties of the product of the present invention as obtained using process 1 of example 5 and the commercially available product.
  • the film sample produced by the process of the present invention has superior lamination strength between the plies and does not delaminate by flexing and stretching using hand. Further, the process of the present invention provides more balanced properties in machine direction and cross direction compared. Further, the lamination strength of the film of the present application is better than the commercially available cross-laminated film. Peel off or delamination is one of the main failure mode of cross laminated film in product usage as waterproofing, roof underlayment, cover sheets, packaging materials, tarpaulins etc. The product of present invention has better lamination strength compared to commercially available competitor product as indicated by table 7
  • the power and fuel cost for producing cross laminated film as per process 1 and 2 have been compared .
  • the process 1 requires approximately 55 % less power cost compared to process 2 and 33 % less fuel cost compared to process 2.
  • the overall utility cost for producing cross laminated film as per process 1 found to be approximate 48 % less compared to process 2. This is the economic advantage of process 1 compared to process 2.
  • the process 2 requires high capital expenditure in order to minimize the utility cost comparable to process 1.

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Abstract

The present invention relates to the field of cross-laminates having at least two multilayer films of thermoplastic polymer material which are oriented in such a way that the orientation of one film crosses orientation of the other film. Particularly, the present invention relates to a process for producing a cross laminated polymer film having at least two films cross sandwiched with one another in opposite direction.

Description

PROCESS FOR PRODUCING CROSS LAMINATED POLYMER FILM
TECHNICAL FIELD OF INVENTION
The present invention relates to the field of crosslaminates having a plurality of multilayer films of thermoplastic polymer material which are oriented in such a way that the orientation of the one film crosses the orientation of the other film. Particularly, the present invention relates to a process for producing a cross laminated polymer film having a plurality of multilayer films cross sandwiched with one another in opposite direction. The cross laminate film of the present invention has a good tear propagation resistance, good tensile strength and good lamination strength.
BACKGROUND OF THE INVENTION
The cross laminates polymer materials have been commercially produced since 1968 and find extensive use in waterproofing, roof underlayment, air/vapor barrier, industrial bags, cover sheets, packaging materials, tarpaulins etc. It is known in the art that the film made from cross lamination is extremely strong yet light weight, flexible and tougher than any other plastic film of comparable weight and thickness. The polymer compositions of film, which have been industrially used in cross laminates, is mainly based on HDPE, LLDPE (and blends of the two) or crystalline PP.
The process of producing crosslaminates usually comprises making multilayered blown film keeping the molecular orientation in the direction of machine operation, spiral cutting the film to the machine direction with a specific angle and laminating together the layers of the spiral cut films, with orientations at opposite angles. The cross- laminated film usually goes through a stretching process in different directions, so that the molecules of the final product are isotropically oriented. Such process of cross lamination highly enhances the tensile strength of the film by modifying the molecular arrangement and physical structure of the blown films. Thus, crosslaminates made from similar polymers exhibit improved tear propagation resistance compared to a simply biaxially oriented film.
There have been several methods in the art for producing desired combination of tensile strength and tear propagation resistance in cross laminated films. For example, US2009/0233041 describes method for cross laminating the films wherein a cross laminate is formed from uniaxially or unbalanced biaxially oriented and the main direction of one of these films cross the main direction of another. Particularly, the coextrusion of film with lamination layer is carried out, film is uniaxially melt oriented in machine direction followed by longitudinal stretching between series of smooth rollers and sequential transverse stretching between special grooved rollers (semi fibrillation) and stabilization by heat, cooling and winding up the film which is further helically cut, wound up and then cross lamination with similar ply and allowing shrinkage to obtain the final cross laminate.
US 7,976,925 describes a process for preparation of cross laminate polymer whereby cross laminate is formed from tubular films formed by co-extrusion and helically cutting of the films followed by cross sandwiching in opposite direction followed by lamination. The intent of this invention was to provide an improved and simplified strong bond/ weak bond system for the cross laminate by use of extrusion and/ or provide it with improved aesthetics. This invention mainly concerns having modification of the surface properties of the two films in a suitable pattern in such a way that the internally arranged surfaces of the films comprise an array of strands of co- extruded material and the array of strands of two films cross one another.
Indian patent application 1432/CHENP/2011 discloses a method and apparatus for manufacture of a polymer film, which is oriented under an angle to its longitudinal direction. The manufacture of an oriented film for cross-lamination requires stabilization of the orientation prior to the lamination to reduce the internal tensions which build up when films are stored on reel. Therefore, this invention mainly concerns reduction in such stabilization problems by carrying out the stretching in the tumbling unwinder, which is used in connection with the helical cutting, to ensure stabilization of the films after the helical cutting.
The processes known in the art show that the modification of various steps of the producing a crosslaminate improve the properties of the final product. It is observed that most the research in the art is based on the significance of longitudinal stretching, segmental stretching, semi-fibrillation, etc. to obtain a cross laminate with desired tear propagation resistance and improved tensile strength. However, such processes are time consuming and require additional equipment resulting in huge processing costs to obtain the final product. The main purpose of the present invention is to reduce such processing costs using simple production steps in the manufacture of cross laminates without compromising the desired properties of the cross laminated polymer films.
SUMMARY OF THE INVENTION
The present invention relates to a process for producing a cross laminated polymer film. Particularly, cross-laminates having a plurality of multilayer films of thermoplastic polymer material are produced in the present invention in which the orientation of the one film crosses the orientation of the other film. The present invention produces a cross laminated polymer film having a good tear propagation resistance, good tensile strength and good lamination strength using simplified process steps thereby providing economic advantage compared to the processes known in the art.
According to one aspect, the present invention provides a process for producing cross laminated polymer film comprising the steps of:
a) preparing a plurality of co-extruded multilayer tubular blown films;
b) helical cutting of the tubular blown films at an angle to orient the molecules of films in a direction to obtain oriented flat films;
c) simultaneously cross sandwiching and grooving of the oriented flat films to obtain a single cross sandwiched and grooved film ; and a) laminating the cross sandwiched and grooved film to obtain the cross laminated polymer film.
In another embodiment of the present invention the tubular blown film comprises a thermoplastic polymer.
In another embodiment of the present invention the thermoplastic polymer is selected from the group consisting of HDPE, LLDPE, mLLDPE, LDPE and a combination thereof.
In another embodiment of the present invention the tubular blown film optionally comprises polyolefin plastomers in the range of 0-10 wt %.
In another embodiment of the present invention the tubular blown film further comprises a color master batch in the range of 1-5%, UV stabilizers in the range of 1- 5% and additives in the range of 0.5 - 2 % .
In another embodiment of the present invention the tubular blown films have thickness in the range of 20-100 microns.
In another embodiment of the present invention the helical cutting of the tubular blown films comprising the steps of :
i) unwinding tubular blown film with a tumbling movement of unwinding stand from a reel;
ii) inflating the tubular blown film using air to obtain an inflated film; and iii) cutting the inflated film at an angle of 25 to 75 degrees to obtain helically cut film.
In another embodiment of the present invention the simultaneously cross sandwiching and grooving of the oriented flat film comprising the steps of:
a) placing plurality of helically cut films in such a way that the direction of orientation of one film crosses the direction of orientation of neighboring film; and converging the films together to obtain a single layered film; b) optionally, preheating each helically cut blown film individually at a temperature in the range of 80-120 °C before converging the films together;
c) passing the single layer of converged films over plurality of preheated drums at a temperature in the range of 60 -100 °C to obtain a heated single layer.;
d) sandwiching the heated single layer of converged films using grooved roller and smooth rubber roller to obtain cross sandwiched and grooved film.
In another embodiment of the present invention the laminating the cross sandwiched and grooved film comprising passing the cross sandwiched and grooved single layer of film through grooved roller and smooth rubber roller to obtain cross laminated polymer film; said cross sandwiched and grooved single layer of film is heated at a temperature in the range of 80 °C - 120°C using a plurality of preheated drums ;
optionally, heating the cross sandwiched and grooved single layer of film using single heating drum set at temperature in the range of 110 - 135 UC and passing the heated single layer through grooved roller and smooth roller to obtain cross laminated polymer film.
In another embodiment of the present invention the smooth roller having hardness in the range of 40 - 80 A.
In another aspect, the present invention provides a cross laminated polymer film comprising three co-extruded tubular blown films wherein the direction of orientation of each blown film crosses the direction of orientation of the neighboring film; said cross laminated polymer film is prepared by the process comprising the steps of:
a) preparing three co-extruded multilayer tubular blown films individually;
b) helical cutting three tubular blown films individually at an angle to orient the molecules of films in a particular direction to obtain the oriented flat films;
c) simultaneously cross sandwiching and grooving the three oriented flat films to obtain a single cross sandwiched and grooved film; and d) laminating the cross sandwiched and grooved film to obtain the crosslaminated polymer film
In another embodiment of the present invention the tubular blown film comprising: a) middle layer comprising HDPE, LLDPE, mLLDPE,LDPE or a combination thereof and the middle layer is in the range of 40 -80 wt % of total film;
b) outer layer comprising LLDPE, mLLDPE,LDPE or a combination thereof and theouter layer is in the range of 10 -30 wt % of total film; and
c) inner layer comprising LLDPE, mLLDPE ,LDPE or a combination thereof and the inner layer is in the range of 10 -30 wt % of total film;
In another embodiment of the present invention the inner layer and outer layer optionally comprises polyolefin plastomer in the range of 0-10 wt % of total film .
In another embodiment of the present invention the tubular blown film comprises color master batch in the range of 1-5%, UV stabilizers in the range of 1-5% and polymer process additives in the range of 0.5 - 2 % or a combination thereof.
In another embodiment of the present invention the blown films is having thickness in the range of 20-100 microns.
In another embodiment of the present invention the helical cutting of the tubular blown film comprising the steps of :
a) unwinding tubular blown film with a tumbling movement of unwinding stand from a reel;
b) inflating the tubular blown film using air to obtain an inflated film; and c) cutting the inflated film at an angle of 25 to 75 degrees to obtain helically cut film.
In another embodiment of the present invention the simultaneously cross sandwiching and grooving of three oriented flat films comprising the steps of: a) placing three helically cut blown films in such a way that the direction of orientation of one film crosses the direction of orientation of neighboring film and converging the three films together to obtain a single layer of film;
b) Optionally, preheating each layer individually at a temperature in the range of 80-120 °C before converging the films together;
c) passing the single layer of converged films over plurality of preheated drums at a temperature in the range of 60-100 °C to obtain a heated single layer; and d) sandwiching the heated single layer of the converged film using grooved roller and smooth rubber roller to obtain the cross sandwiched and grooved film.
In another embodiment of the present invention the laminating the cross sandwiched and grooved film comprising passing the cross sandwiched and grooved single layer of film through grooved roller and smooth rubber roller to obtain cross laminated polymer film; said cross sandwiched and grooved single layer of film is heated at a temperature in the range of 80 °C - 120°C using a plurality of preheated drums;
optionally, heating the cross sandwiched and grooved film using single heating drum set at temperature in the range of 110 - 135 °C and passing the heated single layer through grooved roller and smooth roller to obtain the cross laminated polymer film.
In another embodiment of the present invention the smooth roller are having hardness in the range of 40 - 80 A.
In another embodiment of the present invention the laminated film has crest and valley pattern.
In another embodiment of the present invention the cross laminated polymer film is having pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm. In another embodiment of the present invention the crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer film.
In another embodiment of the present invention the weight of the cross laminated polymer film is in the range of 50 - 300 gsm.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description, appended claims, and accompanying drawings where:
Fig. 1 shows the schematic presentation of the film orientation (A) before helical cutting and (B) after 45 degree helical cutting.
Fig. 2 shows schematic presentation of layered arrangement with orientation of the films.
Fig. 3 shows the schematic diagram of simultaneous cross sandwiching and grooving process. 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating drums, 7A is rubber roller, 8 is grooved roller and 9 is winder.
Fig. 4 shows the schematic diagram of lamination of cross sandwiched and grooved film. 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating drums, 7B is rubber roller, 8 is grooved roller and 9 is winder.
Fig. 5 A -shows the straight grooved roller design having and valley structure having groove depth in the range of 0.2-2mm, groove width in the range of 0.2-2mm and pitch in the range of 0.6-4mm., 5 B shows square grooved roller design having groove depth in the range of 0.2-5 mm, groove width in the range of 0.2-5 mm and square groove pattern in the range of lxl mm to 20x20mm. 5 C shows diamond grooved roller design having groove depth in the range of 0.2-5 mm, groove width in the range of 0.2-5 mm and square groove pattern in the range of lxl mm to 20x20mm.
Fig. 6 shows the schematic diagram of individual grooving of helically cut films.
1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating driums, 7A is rubber roller, 8 is grooved roller and 9 is winder.
Fig. 7 shows the schematic diagram of lamination of individually grooved films.
1 , 2 and 3 are Let off Rollers, 4 is Idle rollers, 5 and 6 are heating driums, 7B is rubber roller, 8 is grooved roller and 9 is winder.
Fig. 8 shows the schematic diagram of cross sandwiching, grooving and lamination in single line. 1, 2 and 3 are Let off Rollers, 4 is Idle rollers, 5, 6, 7 and 8 are heating drums, 9 A and 9B are rubber roller, 10A and 10 B are grooved roller and 11 is winder.
DETAILED DESCRIPTION OF INVENTION
The present invention relates to the field of cross-laminates having at least two multilayer films of thermoplastic polymer material which are oriented in such a way that the orientation of one film crosses orientation of the other film. Particularly, the present invention relates to a process for producing a cross laminated polymer film having at least two films cross sandwiched with one another in opposite direction. The cross laminate film of the present invention has a good tear propagation resistance ,good tensile strength and good lamination strength.
The present invention relates to development of a process for producing cross laminated polymer film comprising the steps of:
(a) preparing plurality of co-extruded multilayer tubular blown films; (b) helical cutting the tubular blown films at an angle to orient the molecules of films in a direction followed by unfolding helically cut films to obtain the oriented flat films;
(c) simultaneously cross sandwiching and grooving of the oriented flat films to obtain a single cross sandwiched and grooved film; and
(d) laminating the cross sandwiched and grooved film to obtain the crosslaminated polymer film.
Step (a): Preparation of co-extruded multilayer blown film
The multilayered co-extruded tubular blown films are produced using thermoplastic polymer material with the following compositions:
a) Middle layer : 40 -80 % of total film with polymers selected from HDPE,LLDPE,mLLDPE,LDPE or combination of any two or all three. b) Outer Layer: 10 -30 % of total film with polymers selected from LLDPE or mLLDPE or LDPE or combination thereof with 0 -10 % polyolefin plastomers
c) Inner Layer: 10 -30 % of total film with polymers selected from LLDPE or mLLDPE or LDPE or combination thereof with 0 -10 % polyolefin plastomers
The blown up ratio in the range of 1: 1 to 4: 1 and Longitudinal draw down ratio of 10: 1 to 40: 1 were used to obtain the multilayered blown films and Color master batch (1 - 5 %) and UV stabilizers (1- 5 %), polymer process additives ( 0.5 -2.0 %) were blended with each layer. The thickness of the blown films obtained was in the range of 20 - 100 Microns. Step (b): Helical cutting of Tubular Blown film
The objective of helical cutting is to unfold a tubular film obtained in step (a) to a flat film with a change in orientation of molecules. The helical cutting process is carried out by unwinding tubular blown film from a reel in an unwinding stand which performs a tumbling movement. The purpose of tumbling movement is to rotate the lay - flat film around its longitudinally extending middle line. The lay flat tube is inflated using air which is blown from the back side of the mandrel. The mandrel provides a solid support for the inflated film. The cutting taking place using a knife located in a fixed position at an angle of 25 to 75 degrees and the helically cut film is pulled away from the mandrel to the winder.
Step (c): Simultaneous cross sandwiching and grooving of helically cut films
As shown in figure 3 the tubular blown films 1 , 2 and 3 are helically cut as explained in step (b) above and unfolded to flat films with change in orientation of molecules of films as shown in figure 2 and the films are termed as Helically cut films 1, 2 and 3, respectively (figure 2). These helically cut films are placed in such a way that their orientations are at opposite direction i.e. the orientation criss - cross each other and the lamination layer of each film are in contact with each other.
As shown in Figure 3, the helically cut films 1, 2 and 3 are placed in the let off rollers 1, 2 and 3 (rendered flat as explained above in step (b)) in such a way that when sandwiched to form a single layer, their orientations are opposite to each other and lamination layer in each film is in contact with each other. These 3 films are converged together using series of idle rollers (4) at temperature in the range of 25 -40°C. There is no lamination between the films at this stage as the process is done at room temperature. The converged film as shown in figure 3 follows first preheating drum (5) set at 60-100 °C followed by second heating drum (6) set at 70-110 °C. The converged film follows the path in such a way that both sides of the film get heated. Optionally, preheating each film individually at a temperature in the range of 80-120 C before converging the films together;
The heated film is then sandwiched using grooved steel roller (8) (having straight groove pattern) and smooth rubber roller (7 A) having hardness 40 - 80 A to obtain the cross-laminate film with pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm. and the crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer film. Since the temperature of the second drum (6) is lower than the melting point (lower by at least 10 degree) of the lamination layer, the sandwiched film will not be strongly laminated. At the same time, the film will soften and grooving using grooved roller and rubber roller results in weak lamination over the entire film. This will also introduce a grooving pattern i.e. crest and valley over the sandwiched film. After simultaneous sandwiching and grooving using grooved and rubber roller unit, the film passes through a series of idling (4) transfer rollers as shown in figure 3. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 0 - 25 % stretching in machine direction and helps to make the grooving pattern even. The simultaneously cross sandwiched and grooved has very low lamination between the plies and can be easily delaminated by repeated flexing and rubbing by hand.
Different grooved roller patterns like square groove, diamond groove patterns can be used to create different design pattern on final film as shown in fig 5.
Step (d): Lamination of cross sandwiched and grooved film
As shown in figure 4, the cross sandwiched and grooved film passes first preheating drum (5) set at 70-110 °C followed by second heating drum (6) set at 80 -120 °C.The film follows the path in such a way that both sides of the film get heated. The heated film is then laminated using same grooved steel roller (8) and smooth rubber roller (7 B) of hardness 40-80 A. Optionally the cross sandwiched and grooved film can be directly heated and laminated using single heating drum set at higher temperature in the range of 110 - 135 C. In that case preheating is not required. Since the temperature of the second drum is very close to the melting temperature of the lamination layer, the sandwiched film will be heat sealed. However, the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite. The lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film. After lamination, the film passes the idling transfer roller (4). The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 0 - 25 % stretching in machine direction. This helps to make the grooving pattern even. The cross sandwiched and grooved film from the transfer roller (4) is then wound up on a roller (9) with winding tension as low as possible to allow shrinkage. The final cross laminate film obtained is in the range of 50 - 300 gsm.
The cross laminate film obtained in step (d) has crest and valley pattern with pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm. and the crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer. Overall the laminated cross laminate film of the present invention has good lamination strength and cannot be delaminated by repeated flexing and rubbing by hand.
Different grooved roller patterns like square groove, diamond groove patterns can be used to create different design pattern on final film.
Alternatively the cross sandwiching, grooving and lamination can also be performed in a single line as per the drawing 8.
Although enormous research has been carried out in the field, there have been no prior studies to carry out simultaneous cross sandwiching and grooving of helically cut films followed by lamination using grooved roller to obtain a cross laminated polymer film having a good tensile strength and tear propagation resistance as obtained in the crosslaminate film of the present invention. EXAMPLES
The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of present disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the subject matter.
Example 1: Process For Preparation Of Cross Laminated Polymer Film
Three multilayered tubular blown films were co-extruded having following composition (as shown in figure 2):
Film 1 : Middle layer - 70 % of total comprising HDPE of MFI (Melt flow index)- 0.3 and density - 0.944 g/ml, Outer Surface layer - 20 % of total comprising LLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 10 % of total comprising mLLDPE of MFI - 1.0
Film 2: Middle layer - 70 % of total comprising HDPE of MFI - 0.3 and density - 0.944 g/ml, Outer Surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
Film 3: Middle layer - 70 % of total comprising HDPE of MFI - 0.3 and density - 0.944 g/ml, Outer Surface layer - 10 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 20 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
Blown up Ratio used was 2.5: 1 and Longitudinal draw down ratio used wasl6: l. Color master batch (4 %), UV stabilizers (3 %) and additive (0.75 %) were blended with each layer. The thickness of films 1, 2 and 3 was 55 Micrometer. Difference in modulus of Elasticity of films used in the product is less than 15 % and are given below
Figure imgf000016_0001
In a separate process line, the tubular films were helically cut at an angle of 45°. As shown in figure 3, the helically cut films 1, 2 and 3 each are placed in the let off rollers 1 , 2 and 3 and these 3 films are converged together using idle rollers (4) at 30°C in such a way that their orientations are opposite to each other during sandwiching and lamination layer in each of the films 1, 2, 3 are in contact with each other. There is no lamination between the films as the process is done at 30° C. The converged film follows first preheating drum (5) set at 90°C followed by second heating drum (6) set at 100°C. The converged film follows the path in such a way that both sides of the film get heated. The heated film is then sandwiched using grooved steel roller (8) (having straight groove pattern as shown in figure 5 with pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and crest depth in the range of 0.2 to 2.0 mm and valley width in the range of 0.5-3.0 mm and crest thickness of the film obtained 100 % of valley thickness.) and smooth rubber roller (7 A) having hardness of 55 A. Since the temperature of the second drum is lower than the melting point (lower by at least 10 degree) of the lamination layer, the sandwiched film will not be strongly laminated. At the same time, the film will soften and grooving using grooved roller and rubber roller results weak lamination over the entire film. This will also introduce a grooving pattern i.e. crest and valley over the sandwiched film. After simultaneous sandwiching and grooving using grooved and rubber roller unit, the film passes the series of idling (4) transfer rollers. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction which helps to make the grooving pattern even. The film is then wound up on a roller (9) with winding tension as low as possible to allow shrinkage. The cross sandwiched and grooved film has very low lamination between the plies and can be easily delaminated by repeated flexing and rubbing by hand. However the laminate at this stage doesn't delaminate during the next process i.e. final lamination.
As shown in figure 4, lamination of Cross Sandwiched and grooved film using grooved roller is carried out. The cross sandwiched and grooved film passes first preheating drum 1 (5) set at 100 °C followed by second heating drum ( 6) set at 112°C. The film follows the path in such a way that both sides of the film get heated. The heated film is then laminated using same grooved steel roller (8) and smooth rubber roller (7 B) of hardness 70 A. Since the temperature of the second drum is very close to the melting temperature of the lamination layer, the sandwiched film will be heat sealed. However, the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite. The lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film. After lamination the film which helps to make the grooving pattern even. The film then wound up on a roller with winding tension as low as possible to allow shrinkage. The final cross laminate film obtained has 150 gsm.
Example 2: Comparative Process With Individual Grooving Of Helically Cut Films
The process of the present invention has also been compared with individual grooving process where the helically cut films were individually grooved first using grooved roller followed by the lamination of individually grooved films. The co-extruded multilayered tubular blown films and helical cutting was carried out similar to example 1. The process of example 2 is carried out like example 1 except for grooving process which takes place individually as shown in figure 5 and lamination is carried out as shown in figure 6. The helically cut film 1 passes through first heating drum ( 5) set at 90 °C and second heating drum ( 6) set at 100 °C. The heated film is then grooved using grooved steel roller (8) and smooth rubber roller (7 A). This will also introduce a grooving pattern i.e. crest and valley over the film. The film then passes the idling (4) transfer roller. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction. This helps to make the grooving pattern even. The film then wound up on a roller (9) with winding tension as low as possible to allow shrinkage. The same process is repeated for helically cut films 2 and 3 to introduce the grooving pattern.
The individually grooved films 1, 2 and 3 are then placed in the let off rollers 1, 2 and 3 in such a way that after sandwiching their orientations are opposite to each other and lamination layer in each film get in contact with each other. These three films are converged together using idle rollers (4) at room temperature. There is no lamination between the films as the process is done at room temperature. The converged film follows first preheating drum (5) set at 100 °C followed by second heating drum (6) set at 112 °C .The converged film follows the path in such a way that both sides of the film get heated. The heated film is then laminated using grooved steel roller (8) and smooth rubber roller (7 B). Since the temperature of the second drum is very close to the melting temperature of the lamination layer, the grooved film will be heat sealed. However the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite. The lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film. After lamination the film passes the idling transfer roller. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction. This helps to make the grooving pattern even. The film then wound up on a roller with winding tension as low as possible to allow shrinkage. The final gsm of the product obtained is 150 gsm. Example 3: Comparision Between Process And Product Of Example 1 And Example 2
Lab trials were carried out for cross laminated film samples produced from example 1 (process 1) and example 2 (process 2). Four runs have been carried out for each process and cross laminated film products were compared for tensile strength and tear resistance and other desired properties which have been summarized in table 1 to table 5 below:
Table 1 - Comparison between the steps of processes of Example 1 and Example 2
Figure imgf000019_0001
Table 2: Comparison of Tensile strength ( Kg/cm2) as per ASTM D 882 - of the products obtained using process 1 and process 2
Figure imgf000020_0001
Table 3: Comparison of Elongation at break ( EBR in %) as per ASTM D 882 Remarks Difference is Significant as per T - Difference is Significant as per T - test at 95 % Confidence level test at 95 % Confidence level
Table 4: Comparison of Elmendorf tear strength ( Kg) as per ASTM D 1422
Figure imgf000021_0001
Table 5: Comparison of other important properties for cross laminated polymer film of process 1 and process 2
Figure imgf000021_0002
4 Dart Impact test gm. ASTM D 1709 740 720
5 *Delamination gm./2.5 cm *In house test No No
test - MD Method delamination delamination
*Delamination test - Delaminate the film sample by hand stretching and separate the individual plies. Delaminate 50 mm across the length and fix one of the individual ply in the delaminated film on top jaw of Universal testing Machine (UTM) (Instron 3365) and other plies on the bottom jaw of Universal testing Machine. The film is then delaminated using Instron (Universal testing Machine) by moving the top jaw along the ply at 250 mm/min. The delamination strength will be recorded instantaneously and reports the average value. The gauge length is 50 mm and sample length should be min 100 mm with width 25 mm. The delamination strength in Cross direction also can be calculated in the same procedure.
As shown in the tables 2-5, most of the properties of cross laminated polymer film produced by process 1 are comparable to the properties of film produced by process 2 except the tensile strength at break in cross direction and elongation at break in machine and cross direction. The tensile strength in cross direction and Elongation at Break in MD and CD of film produced by process 1 are better compared to the one produced by process 2. The process 1 of the present invention having simultaneous cross sandwiching and grooving step requires less processing time compared to process 2 comprising individual grooving of the films. The other way is to groove the individual films in three different lines which will reduce the processing time. However, this necessitates additional line for grooving process hence huge investments and more power and fuel consumption. Hence, the process 1 has economical advantage over process 2 with comparable or better final product characteristics. EXAMPLE 4: COMPARISON AGAINST COMMERCIALLY AVAILABLE CROSS LAMINATED FILM PRODUCT
The lab trial film samples produced by process 1 of the present invention have also been compared with a well-known commercially available cross laminated film product of the same gsm - 150gsm. Table 6 shows the comparative properties of the product of the present invention as obtained using process 1 and the commercially available product.
Table 6 - Comparison of film of Process- 1 against commercially available product
Figure imgf000023_0001
The lab samples were also tested for other important properties for cross laminated polymer films and results are tabulated in table 7 against commercially available product of 150 gsm.
Table 7 - Comparison of film of Process -1 against commercially available product
Figure imgf000024_0001
As shown in tables 6 and 7, the tensile strength at break in CD, EBR in MD and CD, Elmendorf tear strength in MD, Delamination strength in MD and CD of process 1 film samples are significantly different from the commercially available product. Hence, the product is different from the commercially available product. Example 5: Process For Preparation Of Cross Laminated Polymer Film
Three multilayered tubular blown films were co-extruded having following composition (as shown in figure 2):to reduce the stiffness of the final product.
Film 1 : Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 38.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 8.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising LLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
Film 2: Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml
Film 3: Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 38.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 8.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising mLLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising LLDPE of MFI - 1.0 and density 0.918 g/ml
Blown up Ratio used was 2.5: 1 and Longitudinal draw down ratio used wasl6: l. Color master batch, UV stabilizers and polymer process additives were blended with each layer. Film thickness of films 1, 2 and 3 was 54 Micrometer. Difference in modulus of Elasticity of films used in the product is less than 15 % and are given below
Figure imgf000026_0001
In a separate process line, the tubular films were helically cut at an angle of 45°. As shown in figure 3, the helically cut films 1, 2 and 3 each are placed in the let off rollers 1, 2 and 3 and these 3 films are individual heated using heating drum set at 105 C. The films are placed in the let off rollers in such a way that their orientations are opposite to each other during sandwiching and lamination layer in each of the films 1, 2, 3 are in contact with each other. The heated films are then sandwiched using grooved steel roller (8) (having straight groove pattern as shown in figure 5 with pitch, crest width and valley width of 2.4mm, 0.9mm and 1.5mm, respectively and Crest thickness of the film obtained 100 % of valley thickness.) and smooth rubber roller (7 A) having hardness of 70 A. Since the temperature of the second drum is lower than the melting point (lower by at least 10 degree) of the lamination layer, the sandwiched film will not be strongly laminated. At the same time, the film will soften and grooving using grooved roller and rubber roller results weak lamination over the entire film. This will also introduce a grooving pattern i.e. crest and valley over the sandwiched film. After simultaneous sandwiching and grooving using grooved and rubber roller unit, the film passes the series of idling (4) transfer rollers. The downstream roller moves faster compared to upstream roller after sandwiching and grooving and results at least 5 % stretching in machine direction which helps to make the grooving pattern even. The film is then wound up on a roller (9) with winding tension as low as possible to allow shrinkage. The cross sandwiched and grooved film has very low lamination between the plies and can be easily delaminated by repeated flexing and rubbing by hand. However the laminate at this stage doesn't delaminate during the next process i.e. final lamination.
As shown in figure 4, lamination of Cross Sandwiched and grooved film using grooved roller is carried out. The cross sandwiched and grooved film passes the heating drum set at 127 °C. The heated film is then laminated using same grooved steel roller (8) and smooth rubber roller (7 B) of hardness 70 A. Since the temperature of the heating drum is very close to the melting temperature of the lamination layer, the sandwiched film will be heat sealed. However, the lamination temperature is at least 10 degrees lower compared to the melting temperature of the film composite. The lamination using grooved roller will introduce grooving pattern i.e. crest and valley pattern over the laminated film. The film then wound up on a roller with winding tension as low as possible to allow shrinkage. The final cross laminate film obtained has 150 gsm.
Example 6 : Process For Preparation Of Cross Laminated Polymer Film
This is carried out like example 5 except for individual film thickness of coextruded multilayer blown film thickness are 32 micrometer and Longitudinal draw down ratio used was 26: 1. The final cross laminate film obtained has 90 gsm.
Difference in modulus of Elasticity of films used in the product is less than 15 % and are given below
Figure imgf000027_0001
Example 7: Process For Preparation Of Cross Laminated Polymer Film
This is carried out like example 5 except for the lamination layer in individual film comprises 5 % polyolefin plastomer to improve the lamination strength between the films.
Film 1 : Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 38.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 8.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising LLDPE of MFI - 1.0 and density 0.918 g/ml, Inner surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer ( 5%) of MFI - 1.0 and density 0.904 g/ml
Film 2: Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 23.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer ( 5%) of MFI - 1.0 and density 0.904 g/ml, Inner surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer (5%) of MFI - 1.0 and density 0.904g/ml
Film 3: Middle layer - 70 % of total comprising a combination of polymers HDPE ( 23.3%) of MFI - 0.3 and density - 0.944 g/ml and mLLDPE ( 38.3%) of MFI - 1.0 and density 0.918 g/ml and LLDPE ( 8.3%) of MFI - 1.0 and density 0.918 g/ml , Outer Surface layer - 15 % of total comprising a combination of polymers mLLDPE ( 10%) of MFI - 1.0 and density 0.918 g/ml and Polyolefin plastomer ( 5%) of MFI - 1.0 and density 0.904g/ml, Inner surface layer - 15 % of total comprising LLDPE of MFI - 1.0 and density 0.918 g/ml Difference in modulus of Elasticity of films used in the product is less than 15 % and are given below
Figure imgf000029_0001
The final cross laminate film obtained has 90 gsm
Table 8 - Comparison of film of Process -1 produced as per example 5, 6 and 7
Figure imgf000029_0002
N -120)
4 Elongation at % ASTM D 927 (SD - 827 ( SD - 797 (SD - Break - CD ( 882 94.2) 92.2) 84.0) N -120)
5 Elmendorf gm ASTM D 4050 ( SD - 2525 ( SD - 2534 (SD - tear strength - 1422 624) 422) 510) MD ( N -120)
6 Elmendorf gm ASTM D 3550 ( SD - 2836 (SD - 3019 (SD- tear strength - 1422 548) 498) 669.0) CD ( N -120)
Example 8: Comparison Against Commercially Available Cross Laminated Film Product
The cross laminated film produced by process 1 of the present invention have also been compared with a well-known commercially available cross laminated film product of the same gsm - 150gsm. Table 9 shows the comparative properties of the product of the present invention as obtained using process 1 of example 5 and the commercially available product.
Table 9 - Comparison of film of Process- 1 produced as per example 5 against commercially available product
Figure imgf000031_0001
The trial film samples were also tested for other important properties for cross laminated polymer films and results are tabulated in table 7 against commercially available product of 150 gsm.
Table 7 - Comparison of film of Process -1 produced as per example 5 against commercially available product
Figure imgf000032_0001
ADVANTAGES OF THE INVENTION
The film sample produced by the process of the present invention has superior lamination strength between the plies and does not delaminate by flexing and stretching using hand. Further, the process of the present invention provides more balanced properties in machine direction and cross direction compared. Further, the lamination strength of the film of the present application is better than the commercially available cross-laminated film. Peel off or delamination is one of the main failure mode of cross laminated film in product usage as waterproofing, roof underlayment, cover sheets, packaging materials, tarpaulins etc. The product of present invention has better lamination strength compared to commercially available competitor product as indicated by table 7
The power and fuel cost for producing cross laminated film as per process 1 and 2 have been compared .The process 1 requires approximately 55 % less power cost compared to process 2 and 33 % less fuel cost compared to process 2. The overall utility cost for producing cross laminated film as per process 1 found to be approximate 48 % less compared to process 2. This is the economic advantage of process 1 compared to process 2. Alternatively The process 2 requires high capital expenditure in order to minimize the utility cost comparable to process 1.
Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Claims

We claim:
1. A process for preparing cross laminated polymer film comprising the steps of: a) preparing a plurality of co-extruded multilayer tubular blown films; b) helical cutting of the tubular blown films at an angle to orient the molecules of films in a direction to obtain oriented flat films; c) simultaneously cross sandwiching and grooving of the oriented flat films to obtain a single cross sandwiched and grooved film ; and d) laminating the cross sandwiched and grooved film to obtain the crosslaminated polymer film.
2. The process as claimed in claim 1, wherein the tubular blown film comprises a thermoplastic polymer.
3. The process as claimed in claim 2, wherein the thermoplastic polymer is selected from the group consisting of HDPE, LLDPE, mLLDPE, LDPE and a combination thereof.
4. The process as claimed in claim 2, wherein the tubular blown film optionally comprises polyolefin plastomers in the range of 0-10 wt%.
5. The process as claimed in claim 1, wherein the tubular blown film further comprises a color master batch in the range of 1-5 wt%, UV stabilizers in the range of 1-5 wt% and additives in the range of 0.5 - 2 wt% .
6. The process as claimed in claim 1, wherein the tubular blown films have thickness in the range of 20-100 microns.
7. The process as claimed in claim 1, wherein the helical cutting of the tubular blown films comprises the steps of : i) unwinding tubular blown film with a tumbling movement of unwinding stand from a reel; ii) inflating the tubular blown film using air to obtain an inflated film; and iii) cutting the inflated film at an angle of 25 to 75 degrees to obtain helically cut film.
8. The process as claimed in claim 1, wherein the simultaneously cross sandwiching and grooving of the oriented flat film comprises the steps of:
a) placing plurality of helically cut films in such a way that the direction of orientation of one film crosses the direction of orientation of neighboring film; and converging the films together to obtain a single layered film;
b) optionally, preheating each helically cut blown film individually at a temperature in the range of 80-120 °C before converging the films together;
c) passing the single layer of converged films over plurality of preheated drums at a temperature in the range of 60-100 °C to obtain a heated single layer.;
d) sandwiching the heated single layer of converged films using grooved roller and smooth rubber roller to obtain cross sandwiched and grooved film.
9. The process as claimed in claim 1, wherein laminating the cross sandwiched and grooved film comprises passing the cross sandwiched and grooved single layer of film through grooved roller and smooth rubber roller to obtain cross laminated polymer film; said cross sandwiched and grooved single layer of film is heated at a temperature in the range of 80 °C - 120°C using a plurality of preheated drums ;
optionally, heating the cross sandwiched and grooved single layer of film using single heating drum set at temperature in the range of 110 - 135 UC and passing the heated single layer through grooved roller and smooth roller to obtain cross laminated polymer film.
10. The process as claimed in claim 8 and 9, wherein the smooth roller having hardness in the range of 40 - 80 A.
11. A cross laminated polymer film comprising three co-extruded tubular blown films wherein the direction of orientation of each blown film crosses the direction of orientation of the neighboring film; said cross laminated polymer film is prepared by the process comprises the steps of:
a) preparing three co-extruded multilayer tubular blown films individually;
b) helical cutting three tubular blown films individually at an angle to orient the molecules of films in a particular direction to obtain the oriented flat films;
c) simultaneously cross sandwiching and grooving the three oriented flat films to obtain a single cross sandwiched and grooved film; and
d) laminating the cross sandwiched and grooved film to obtain the crosslaminated polymer film
12. A cross laminated polymer film as claimed in claim 11 wherein the tubular blown film comprises:
a) middle layer comprises HDPE, LLDPE, mLLDPE, LDPE or a combination thereof and the middle layer is in the range of 40 -80 wt% of total film;
b) outer layer comprises LLDPE, mLLDPE, LDPE or a combination thereof and the outer layer is in the range of 10 -30 wt% of total film; and
c) inner layer comprises LLDPE, mLLDPE, LDPE or a combination thereof and the inner layer is in the range of 10 -30 wt% of total film;
13. The cross laminated polymer film as claimed in claim 11, wherein the inner layer and outer layer optionally comprises polyolefin plastomer in the range of 0-10 wt% of total film.
14. The cross laminated polymer film as claimed in claim 12, wherein the tubular blown film comprises color master batch in the range of 1-5 wt%, UV stabilizers in the range of 1-5 wt% and polymer process additives in the range of 0.5 - 2 wt% or a combination thereof.
15. The cross laminated polymer film as claimed in claim 11, wherein the blown films is having thickness in the range of 20-100 microns.
16. The cross laminated polymer film as claimed in claim 11, wherein the helical cutting of the tubular blown film comprises the steps of :
a) unwinding tubular blown film with a tumbling movement of unwinding stand from a reel;
b) inflating the oriented flat film using air to obtain an inflated film; and
c) cutting the tubular blown film at an angle of 25 to 75 degrees to obtain helically cut film.
17. The cross laminated polymer film as claimed in claim 11, wherein the simultaneously cross sandwiching and grooving of three oriented flat films comprises the steps of:
a) placing three helically cut blown films in such a way that the direction of orientation of one film crosses the direction of orientation of neighboring film and converging the three films together to obtain a single layer of film;
b) optionally, preheating each layer individually at a temperature in the range of 80-120 °C before converging the films together;
c) passing the single layer of converged films over plurality of preheated drums at a temperature in the range of 60-100 °C to obtain a heated single layer; and
d) sandwiching the heated single layer of the converged film using grooved roller and smooth rubber roller to obtain the cross sandwiched and grooved film.
18. The cross laminated polymer film as claimed in claim 11, wherein laminating the cross sandwiched and grooved film comprises passing the cross sandwiched and grooved single layer of film through grooved roller and smooth rubber roller to obtain cross laminated polymer film; said cross sandwiched and grooved single layer of film is heated at a temperature in the range of 80 °C - 120°C using a plurality of preheated drums;
optionally, heating the cross sandwiched and grooved film using single heating drum set at temperature in the range of 110 - 135 °C and passing the heated single layer through grooved roller and smooth roller to obtain the cross laminated polymer film.
19. The cross laminated polymer film as claimed in claim 17 and 18, wherein the smooth roller are having hardness in the range of 40 - 80 A.
5 20. The cross laminated polymer film as claimed in claim 11, wherein the laminated film has crest and valley pattern.
21. The cross laminated polymer film as claimed in claims 11 and 20, wherein the cross laminated polymer film is having pitch in the range of 0.6 -4.0 mm, crest width in the range of 0.2 -2.0 mm and valley width in the range of 0.5-3.0 mm.
10 22. The cross laminated polymer film prepared by the process as claimed in claim
20, wherein crest thickness of the cross laminated polymer film is 20 to 200 % higher than that of valley thickness of cross laminated polymer film.
23. The cross laminated polymer film as claimed in claim 11, wherein weight of the cross laminated polymer film is in the range of 50 - 300 gsm.
15
PCT/IN2016/050384 2015-11-06 2016-11-04 Process for producing cross laminated polymer film WO2017077555A1 (en)

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IN3636/DEL/2015 2015-11-06

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US20090233041A1 (en) * 2005-05-11 2009-09-17 Ole-Bendt Rasmussen Crosslaminate of oriented films and methods and apparatus for manufacturing same

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
US5248366A (en) * 1988-06-24 1993-09-28 Rasmussen O B Method for helical cutting of a flexible tubular sheet of polymeric material
US20090233041A1 (en) * 2005-05-11 2009-09-17 Ole-Bendt Rasmussen Crosslaminate of oriented films and methods and apparatus for manufacturing same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109616005A (en) * 2018-11-15 2019-04-12 永新股份（黄山）包装有限公司 A kind of milky white PE label film and its production method
CN109616005B (en) * 2018-11-15 2021-05-04 永新股份（黄山）包装有限公司 Milky-white PE label film and production method thereof

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