Title of Invention

A METHOD OF PRODUCING A POLYAMIDE FILM

Abstract A method of producing a polyamide film employing vertical multi-layer blown film process characterized in that it produces at least one layer of polyamide with at least one layer of polyolefin on either side of the said polyamide layer, which is subsequently separated from the polyolefin layers.
Full Text FORM 2



THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENT RULES. 2003
COMPLETE SPECIFICATION
[SECTION 10 AND RULE 13]
A METHOD OF PRODUCING A POLY AMIDE FILM"

APPLICANT:

ECOPLAST LIMITED.

NATIONALITY: AN INDIAN COMPANY INCORPORATED UNDER THE

ADDRESS:

COMPANIES ACT, 1956.
4, MAGAN MAHAL, 2ND FLOOR, 215, SIR M. V. ROAD,
ANDHERI (EAST), MUMBAI - 400069, MAHARASHTRA,
INDIA.


THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to a method of producing a polyamide (PA) film.
BACKGROUND OF THE PRESENT INVENTION
The packaging industry needs a tough, puncture resistant film with barrier properties to retain the aroma & flavours of the packed products. It is also necessary to protect the packed contents from ambient oxygen & carbon dioxide. PA films meet all these requirements. They are therefore, extensively used in multiple laminate structures for packaging.
The known cast film process is presently used to produce PA films. The melt of PA resins from the extruder is fed through a flat die. The melt falls like a curtain on a chilled roll. Thereafter, it is drawn in the form of a film by a series of rotating rollers and finally wound in a roll form. During the drawing process the film gets stretched & oriented in the machine direction. Since the physical properties are dependant on the orientation, the cast film has a good strength in the machine direction. But it exhibits poor strength in the cross-machine direction, as the film cannot be oriented in that direction. The cast film properties like mechanical strength and barrier properties are generally improved by orienting the film in two directions by the 'Tentering process', with a single or two stage tenter frames.
A polyamide resin (either homo / co poly / or blends thereof) has a sharp melting point, low viscosity and poor melt strength, which does not permit the resin to be used in a vertical mono-layer blown film process. Therefore, PA films have not been produced till date by using the said blown film process. PA film has also not been so far made by using vertical multi-layer blown film process.
OBJECT OF THE PRESENT INVENTION
The present invention obviates the aforesaid drawbacks by providing a method of producing a PA film using 'the vertical multi-layer blown film process.
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SUMMARY OF THE PRESENT INVENTION
A method of producing a polyamide film employing vertical multi-layer blown film process characterized in that it produces at least one layer of polyamide with at least one layer of polyolefin on either side of the said polyamide layer, and subsequently separating the said polyamide layer from the polyolefin layers.
DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to a method of producing a PA film by a vertical multilayer blown film process using a layer of PA film and a layer of polyolefin, adjacent to both sides of the said PA film. The present invention comprises of utilizing a multilayer (at least three layers) process wherein a polyamide layer is sandwiched between polyolefin layers.
The polyamide resin used for the extrusion can be homo polymer/ co polymer / or blend thereof. The polyolefin resins used can be of any suitable grade of Low Density Polyethylene, or Linear Low Density Polyethylene, or Very Low Density Polyethylene, or Medium Density Polyethylene, or High Density Polyethylene, or blends thereof, with or without additives.
This invention will now be described with reference to figures / drawings accompanying this complete specification, however the said figures only illustrate the invention and in no way limit the same. In the said figures / drawings the same numerals are used to denote the same parts and wherein:
Figure 1 shows the schematic line diagram of the vertical blown film line.
Fig. 2 shows the sectional front view of a vertical multi-layer blown film process die.
In the given figures the vertical blown film line comprises of, the Extruder (1); the die
(2); the cooling ring (3); the air supply inlet (4); the tubular film (5); the guide rollers £6)
supporting the tubular film (5); the collapsing frame (7), the nip rollers (8); the
winder (9); the lay-flat tube (10) that is obtained after the said tubular film (5) passes
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through collapsing frame (7) and the nip rollers (8); the inside layer inlet (11); the middle layer inlet (12); the outside layer inlet (13); the distributor (14); the die lips (15); and the three layer composite film (16) being drawn up from the die (2).
WORKING OF THE PRESENT INVENTION:
The molten PA resins from the middle layer inlet (12) and the molten polyolefin resins from the inside layer inlet (11) as well as the outside layer inlet (13), are forced under pressure through an adapter (not shown) into the die (2). The PA resin thus fed through the extruder, to the die (2), forms the middle layer. The polyolefin resins are thus fed through two or more extruders that are surrounding the extruder through which the molten PA resins are fed to form two or more olefin layers that sandwich the PA layer.
The three layers move independently in the die (2) until they meet just below the die lips (15). The three layers under heat and high pressure within the die (2) flow together to become one composite film (16) that is then drawn up by nip rollers (8).
When the PA resins are introduced from the middle layer inlet (12), they do not fuse with the adjacent polyolefin layers because PA and polyolefin is not compatible. The molten layers that exit from the die lip (15) are drawn vertically upwards by means of nip rollers (8). At the same time the molten layers are oriented / stretched in the transverse direction, to form a tubular film (5) by means of compressed air blown from an air supply inlet (4) through the center of the die (2). The molten layers freeze at a pre-determined height above the die (2) by means of cooled air supplied by a cooling ring (3) and move towards a collapsing frame (7) through a set of guide rollers (6) supporting the tubular film (5). As the nip rollers (8) are vertically drawing up the composite film (16), it gradually collapses by means of the said collapsing frame (7) to form a lay-flat tube (10). The lay-flat tube is then transported to the winder (9) by a set of secondary nip rollers (not shown), after which the edges of the lay-flat tube (10) are trimmed by a cutting arrangement and the two films thus obtained are wound on two tandem winders (not shown). In a subsequent process the PA layer is separated
from the surrounding polyolefin layers, by means of a rewinder (not shown).
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Generally, the polyamide film thickness is between 10 and 40 microns. However, film of thickness as low as 5 microns can be produced through this process. During the production of the blown film, the PA melt is oriented in both the directions to obtain improved mechanical strength and barrier properties.
ADVANTAGES
1) This process offers an alternate method of producing PA films on conventional vertical multi-layer blown film line.
2) The present invention has a lower investment on the equipment as compared to a cast film line.
3) It allows the production of PA films where the market demand is much lower than the required volume to support the investment in a cast film line.
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CLAIMS:
1. A method of producing a polyamide film employing vertical multi-layer blown film process characterized in that it produces at least one layer of polyamide with at least one layer of polyolefin on either side of the said polyamide layer, and subsequently separating the said polyamide layer from the said polyolefin layers.
2. A method as claimed in Claim 1 wherein the method produces three layers and the center/middle layer is of polyamide.
3. A method as claimed in Claim 1, wherein said polyamide is homo polymer, or copolymer, or blends thereof.
4. A method as claimed in Claim 1, wherein said polyolefin is Low Density Polyethylene, Linear Low Density Polyethylene, Very Low Density Polyethylene, Medium Density Polyethylene, High Density Polyethylene.
5. A process as claimed in claim 1, wherein, the said polyamide film is stretched / oriented bi-directionally to obtain an improved mechanical strength & barrier properties.
6. A process substantially as herein described with reference to the drawings accompanying this complete specification.
Dated this 19th day of Dec' 2006.



Himanshu W. Kane Applicants' Patent Agent


To,
The Controller of Patents,
Patent Office,
Mumbai
6

ABSTRACT
A method of producing a polyamide film employing vertical multi-layer blown film process characterized in that it produces at least one layer of polyamide with at least one layer of polyolefin on either side of the said polyamide layer, which is subsequently separated from the polyolefin layers.




Documents:

1594-MUM-2005-ABSTRACT(13-8-2009).pdf

1594-mum-2005-abstract(granted)-(19-3-2010).pdf

1594-mum-2005-abstract.doc

1594-mum-2005-abstract.pdf

1594-MUM-2005-CANCELLED PAGES(13-8-2009).pdf

1594-MUM-2005-CLAIMS(13-8-2009).pdf

1594-mum-2005-claims(granted)-(19-3-2010).pdf

1594-mum-2005-claims.doc

1594-mum-2005-claims.pdf

1594-mum-2005-correspondence(10-4-2007).pdf

1594-MUM-2005-CORRESPONDENCE(13-8-2009).pdf

1594-MUM-2005-CORRESPONDENCE(IPO)-(13-8-2009).pdf

1594-mum-2005-correspondence(ipo)-(26-3-2010).pdf

1594-mum-2005-correspondence-received ver-191205.pdf

1594-mum-2005-correspondence-received ver-191206.pdf

1594-mum-2005-description (complete).pdf

1594-MUM-2005-DESCRIPTION(COMPLETE)-(13-8-2009).pdf

1594-mum-2005-description(granted)-(19-3-2010).pdf

1594-mum-2005-description(provisional)-(19-12-2005).pdf

1594-MUM-2005-DRAWING(13-8-2009).pdf

1594-mum-2005-drawing(granted)-(19-3-2010).pdf

1594-mum-2005-drawings.pdf

1594-MUM-2005-FORM 1(13-8-2009).pdf

1594-mum-2005-form 18(10-4-2007).pdf

1594-mum-2005-form 2(13-8-2009).pdf

1594-mum-2005-form 2(granted)-(19-3-2010).pdf

1594-mum-2005-form 2(provisional)-(19-12-2005).pdf

1594-MUM-2005-FORM 2(TITLE PAGE)-(13-8-2009).pdf

1594-mum-2005-form 2(title page)-(granted)-(19-3-2010).pdf

1594-mum-2005-form 2(title page)-(provisional)-(19-12-2005).pdf

1594-MUM-2005-FORM 3(13-8-2009).pdf

1594-mum-2005-form 5(20-12-2006).pdf

1594-mum-2005-form-1.pdf

1594-mum-2005-form-2.doc

1594-mum-2005-form-2.pdf

1594-mum-2005-form-26.pdf

1594-mum-2005-form-3.pdf

abstract1.jpg


Patent Number 239436
Indian Patent Application Number 1594/MUM/2005
PG Journal Number 13/2010
Publication Date 26-Mar-2010
Grant Date 19-Mar-2010
Date of Filing 19-Dec-2005
Name of Patentee ECOPLAST LTD
Applicant Address 4, Magan Mahal, 2nd Floor, 215, Sir M.V. Road, Andheri (E), Mumbai - 400069.
Inventors:
# Inventor's Name Inventor's Address
1 DESAI JAYMIN B 4, Magan Mahal, 2nd Floor, 215, Sir M.V. Road, Andheri (E), Mumbai - 400069.
2 KHARAS PHEROZE PESTONJI 4, Magan Mahal, 2nd Floor, 215, Sir M.V. Road, Andheri (E), Mumbai - 400069.
PCT International Classification Number C08J5/18
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA