Patent Grant
8268419
The present invention relates to a novel polypouch for packaging of mineral oils e.g. kerosene oil and method of preparation thereof. Said polypouch is made up of multilayered polymeric sheet or film of different inventive thicknesses formed by co-extruded unique combination of low density/linear low density polyethylene, nylon and adhesive resin resulting in negligible permeation loss of packed mineral oils.
Prior art describes the environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials. Thus U.S. Pat. Nos. 6,117,465, 5,942,579 and 5,721,025 describe a pouch made from a monolayer or multilayer film structure such as a two-layer or a three-layer coextruded film containing linear ethylene polymer and a high pressure low density polyethylene as a seal layer. A process for making a pouch for packaging flowable materials using a film structure of a blend of a linear ethylene interpolymer and a high pressure low density polyethylene is also disclosed.
U.S. Pat. No. 5,476,322 discloses a flexible, thin wall, multi-layer plastic film pouch having an open end and possessing high strength resistance against being manually torn or stretched and having heat sealingly laminated side margins and a rigidly brimmed wide mouth open end. This pouch is particularly useful for sealed containment and storage of liquids, solids, granulates and powders such as those commonly stored in other types of containers, e.g., jars, bottles, and cans. Use of this rigid mouth pouch will contribute greatly to source reduction of plastic waste in that this pouch can serve as a prefilled refill that can be conveniently inserted into reusable dispensing bottles, and by repeatedly replacing emptied prefilled refills a dispensing bottle can be reused numerous times. Also, this pouch can serve as a basic stand up container having substantially less disposable plastic than bottles.
U.S. Pat. No. 5,364,486 discloses a polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example milk, including, for example, a pouch made from a multilayer film structure such as a two-layer or a three-layer co-extruded film containing at least one layer of ultra low density linear polyethylene, as a seal layer.
U.S. Pat. No. 5,288,531 discloses a polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example milk, including, for example, a pouch made from a multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of ultra low density linear polyethylene, as a seal layer.
U.S. Pat. No. 5,360,648 discloses a polymer film pouch made from a homogeneously branched substantially linear ethylene inter-polymer film structure for the packaging of flowable materials such as milk, is disclosed. A pouch made from a multilayer film structure such as a two-layer or a three-layer co-extruded film containing at least one seal layer of a homogeneously branched substantially linear polyethylene is also disclosed. A process for making a pouch for packaging flowable materials using a homogeneously branched substantially linear ethylene inter-polymer film structure is also disclosed.
EP No. 0506348 discloses a film suitable for making medical solution pouches includes a first layer of ethylene propylene co-polymer blended with an elastomer; a polymeric adhesive layer; and an outer layer of a polyamide. Nylon 12 and copolymers thereof, nylon 11 and co-polymers thereof, nylon 66, nylon 610, and nylon 66/610 copolymer are especially preferred polyamides. One or more interior layers of at least one polyolefin such as an ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, very low density polyethylene, ionomer, or blends of these materials, can also be included in the structure.
US Patent Application No. 200606083875 discloses lap sealable laminates and pouches that can withstand retort conditions, periods of storage and subsequent rethermalization are described. The laminate includes a core formed from at least one plastic strength layer of, for example, polyester, nylon, cast polypropylene or oriented polypropylene, and a barrier layer formed from ethylene vinyl alcohol copolymer, Nylon-MXD6, polyvinylidene chloride, an inorganic oxide coating or an organic coating. The core includes first and second major surfaces with a high temperature laminating adhesive. A retortable pouch with a longitudinal lap seal can be formed from the laminate on a form-fill-seal machine.
WO 9850230 discloses the use of a heat sealable multilayer film in manufacturing pouches for containing flowable materials which pouches are in tubular form and have transversely heat sealed ends, said film comprising at least one layer comprising about 10% by volume of the overall film structure and is made from an ethylene-styrene copolymer obtained using a single site catalyst polymerization process and one or more of the following layers: (a) at least one interpolymer selected from interpolymers of ethylene and one or more C3-C20 alpha-olefins made by polymerization processes using single site catalyst, non-single site catalyst and mixtures of such catalysts, and blends thereof, said interpolymers having a density in the range of about 0.87 to about 0.940 gm/cc and a melt Index of from about 0.2 to about 20 dg/minute and comprising about 10 to about 90% by volume of the overall film structure; (b) at least one barrier layer selected from nylon polymers comprising about 5 to about 30% by volume of the overall film structure; polyethylene terephthalate polymers comprising about 5 to about 15% by volume of the overall film structure; amorphous nylon comprising about 5 to 30% by volume of the overall structure; ethylene vinyl alcohol comprising about 5 to about 25% by volume of the overall film structure; (c) at least one tie layer comprising about 5 to about 15% by volume of the overall film structure and selected from ethylene vinyl acetate polymer, ethylene acid copolymers, ionomer or anhydride functionalized ethylene copolymers and (d) at least one high pressure ethylene homopolymer.
Indian Patent No. 192193 discloses a stand up pouch for mineral oils which is made up of a co-extruded sheet consisting of three layers wherein outer layer is selected from polypropylene film and a high molecular high density polyethylene film co-extruded with linear low density polyethylene film, the middle film is a low density polyethylene film co-extruded with linear low density polyethylene film and the inner film is high molecular high density polyethylene film co-extruded with linear low density polyethylene film. This patent does not talk about how much permeability of packed kerosene has been achieved actually in the said pouch to avoid any product loss owing to permeation from the pouch.
Packaging of mineral oils such as kerosene oil in the form of polypouch is desired in the rural areas so that people residing in the rural areas can avail the mineral oils especially kerosene oil in small packing of 1 or 2 liters for their kerosene lamps and lanterns. People of rural areas cannot afford canned packaging or jerry can since it increases the price of the packed kerosene oil due to additional cost of the packaging involved.
Another major problem associated with the packaging of these mineral oils such as kerosene oil is their permeability due to their high volatile nature. Several polypouches have been disclosed in the prior art, which are made up of different polymeric materials but none of them discloses any combination of low density polyethylene, nylon and adhesive resin so as to restrict permeation loss of mineral oils to any minimum value. Moreover, none of them discloses any polypouch having innovative sheet or film having optimized thickness and having a layer of nylon which is sandwiched between two polyethylene layers in order to achieve no or negligible permeability of packed mineral oils especially kerosene oil along with the cost effectiveness and sufficient strength.
The main objective of the present invention is to provide novel polypouches for packaging of mineral oils and method of preparation thereof.
Another objective of the present invention is to provide polypouch made up of multilayered polymeric sheet or film of different inventive thicknesses formed by co-extruded unique combination of low density polyethylene, nylon and adhesive resin.
Yet another objective of the present invention is to provide a polypouch which is capable of providing a packing and vending of mineral oils such as kerosene oil in quantities such as 1 or 2 liters.
Yet another objective of the present invention is to provide cost effective packaging of kerosene oil for the rural areas.
Yet another objective of the present invention is to provide a novel polypouch having negligible or no permeability in the range of 0.1% to 0.15% of packed mineral oils e.g. kerosene oil within 100 days period of storage at ambient atmospheric conditions.
The present invention relates to a polypouch that is made up of multilayered polymeric sheet or film of different inventive thicknesses formed by co-extruded unique combination of low density/linear low density polyethylene, nylon and adhesive resin. The polypouch disclosed in the present invention are suitable for the packaging of the mineral oils having flash point higher than 38 deg C. The present polypouch has better sealing and performance properties with negligible permeability along with cost effectiveness.
In order to understand the invention and to see how the different layers of polymeric materials constitute a multilayer film of the present invention with reference to the accompanying drawings.
The present invention relates to a polypouch that is made up of multilayered polymeric sheet or film of different inventive thicknesses formed by co-extruded unique combination of low density polyethylene, linear low density polyethylene, nylon and adhesive resin. The present invention also relates to method of preparation of said polypouches.
In many packaging, there is a need for polypouches with multiple properties such as mechanical strength, barrier to oxygen or permeability, flexibility (or rigidity), moisture and chemical resistance, sealable at high or at low temperature, abrasion resistance, gloss surface and transparency or opacity.
In many cases, the combination of these properties cannot be achieved by using a single material. For this reason manufactures propose multilayer structures that exhibit a mix of the individual performances of the polymers in the multilayer structure.
The inventors with continuous efforts in their laboratories have come upon selected materials the details of which will be disclosed herein after. It is the choice of selected materials, and a combination thereof, along with their concentration and film/sheet thickness which has resulted in the manufacturing of a polypouch with desired properties.
According to present invention polypouch is made up of sheet/film having thickness 55-120μ and preferably 90-115μ wherein said sheet/film is made by co-extrusion of 2 to 25% by weight nylon, 3 to 18% by weight of adhesive resin and 10 to 70% by weight of combination of linear low density/low density polyethylene in which nylon layer or barrier layer (3) is sandwiched between two low density polyethylene/linear low density polyethylene outer and inner layers (1,5); and each adhesive resin layers or tie layer(2,4) is sandwiched between each low density polyethylene layer(1 and 5) and nylon layer or barrier layer(3).
The materials used in the manufacturing of said sheet/film are described herein under:
Nylon—The barrier layer in the multilayered film is made up of nylon having range of variations and in quantities ranging from 2 to 25% by weight. The types of nylon used in the invention are Nylon 6, Nylon 6,6; Nylon 6,6/6; Nylon 6,10; Nylon 6,12; Nylon 11, Nylon 12.
Linear Low/Low density Polyethylene—Linear low density polyethylene (LLDPE) grades (density range 0.905-0.935 g/cc as per ASTM D-1505 method) and Low density polyethylene (LDPE) grades (density range 0.915-0.925 g/cc as per ASTM D-1505 method) are blended together in the ratio ranging from 10 to 70% to form the inner and outer layer of the multilayered film.
Adhesive resins:—Adhesive layer or tie layer is made up of adhesive resins. The adhesive resins used in the present invention are consisting of a modified or unmodified homopolymer or copolymer of ethylene, methyl acrylate, ethyl acrylate, ethylene vinyl acetate, n-butyl acrylate, ethylene vinyl acetate copolymers, ethylene-alpha olefins and blends thereof.
Blown Film Coextrusion Method of Preparation of Polymeric Multilayered Film
Co-extrusion is a process where two or more resins are extruded simultaneously, and is often used to produce multi-layered films. It can be used to improve the barrier properties of films, to reduce cost or produce materials with difficult to achieve or incompatible properties.
The multilayer films are obtained by either co extrusion or extrusion coating of the resins of the different layers to result in a primary thick tube (primary tape) that is quickly cooled to stop or quench the crystallization of the polymers. The resulting quenched thick tube is thereafter reheated to the so-called orientation temperature and then biaxially stretched at this temperature by a tubular solid state orientation process using a trapped bubble. In said solid-state orientation step the primary tape is stretched in the transverse direction (TD) by inflation with air pressure to give a bubble, and in the longitudinal or machine direction (MD) by the differential speed between the two sets of nip rolls that contain the bubble.
It is widely known that with multi-layer films having a sealing layer comprising a polyethylene or an ethylene-alpha-olefin copolymer, the primary tape comprising said layer is preferably submitted to an irradiation step before orientation to improve bubble stability.
Generally therefore, in the industrial manufacture of heat-shrinkable multi-layer films having a sealing innermost layer comprising a polyethylene or an ethylene-.alpha.-olefin copolymer by a tubular process, either all the layers are coextruded, the tape is quenched, irradiated, reheated and oriented, or some of the layers, including the innermost layer that will become the sealing layer of the end packaging material, are extruded, the tape thus obtained is quenched, irradiated and coated by extrusion of the remaining layers thereon, quenched again, reheated and oriented.
Blown film coextrusion is a highly versatile technology covering a wide range of applications including complex structures based on 2 to 7 layers of different materials.
Melted polymer is extruded through a circular die and the tube is filled with air to blow it. Many parameters are adjustable to achieve the right properties but bubble stability is a critical one. For this reason, the rheological behavior of the materials is very important. Due to limited cooling, blown films generally exhibit lowers optical quality than cast films.
For multilayer structures, the choice of the right tie-layer system is key to guarantee both quality and economical performances.
Experimental Description
In order to establish the suitability of the developed polypouches towards the permeability of kerosene oil and for exploring the possibility of packaging kerosene in pouches, different poly film materials were employed for checking the permeation loss. Pouches were made of the following materials, kept under room temperature and their weight loss per day was observed:
Pouches Design & Development
Taking clue from the above screening studies, the multilayered film materials having nylon barrier properties was selected for permeation studies of 120 days. Following test criteria was adopted to study the kerosene permeation loss from pouches:
Pouch Permeation Test Criteria
Based on following analysis, the criteria for testing permeation properties was initially set as 1% of product loss from the pouches and the time period for resulting in this criteria of 1% product weight loss was noted down:
Logic;
Following Californian regulation, (2×0.156) 0.312 g per day can be permitted to permeate from 1 litre pouch
Hence, 1% was kept as the cut-off limit for testing the permeation properties of various types of bottles under test
During the 120 days of kerosene permeation testing in laboratory, it was observed that laminated nylon based poly-films showed negligible permeation and un-laminated film showed permeation of about 0.14%. There was almost negligible product permeation loss from the nylon based poly pouches suggesting that nylon barrier is very effective for containing the permeation loss within minimum levels and definitely much below the initially stipulated permeation limit of 1% within 30 days. Thus, it was decided to select un-laminated film material for further pouch design studies.
Trial Filling of Pouches
Having got sufficient confidence on the efficacy of the nylon barrier properties in poly-films, the actual filling of pouches was undertaken in a specially developed Form-Fill-Seal (FFS) machine. Three different film thicknesses in the range of 55μ to 120μ, were got developed for filling 1 litre kerosene pouches on FFS machines.
The pouches being filled were tested on spot for strength by dropping them on ground, throwing them with force; standing upon them etc. It was found that the pouch material was strong enough to withstand the crude testing that it was subjected to at the time of filling.
After filling of pouches in all three thickness, the individual pouches were suitable coded as A (medium thickness), B (maximum thickness) and C (minimum thickness) before submitting to Indian Institute of Packaging for testing against standard test methods. For the purpose of secondary packaging, 15 pouches of 1 litre each were packed in PP crate having open able top lid. This was done to arrest any vapors of kerosene to come out of the packaging and also to contain kerosene from leaked pouch, if any.
Testing of Pouches at IIP, Mumbai
The following testing protocol was developed primarily to select the optimized thickness of pouches:
All the 3 thickness of pouches were tested as per the protocol above. The pouches in all thickness passed all of the tests.
Performance Testing
Short Duration Storage Stability
The filled pouches were subjected to short duration storage stability testing in the conditioning chamber of Packaging Research lab of IOC R&D Centre at Faridabad, under following conditions each for 48 hours:
10 pouches were kept in the conditioning chamber under each condition and were checked after every 12 hours for any leakage or weight loss. At the end of 48 hours, none of the pouches showed any leakage, abnormal appearance and all the pouches showed negligible permeation loss under each of the test conditions during this test.
Accelerated Storage Stability Test on Filled Pouches
A three month long study was carried out to check the long term accelerated storage stability of pouches with the following objectives:
To assess the basic physico-chemical and physical properties of the packaging materials used for filling the kerosene pouches
To expose the pouches under following accelerated storage conditions:
To draw filled pouches at regular intervals from each of the above storage areas and carry out following product quality and product-package compatibility tests:
Pouch
Appearance of the pouches
Heat Seal Strength
Leakage through pouches
Loss in weight on exposure
Drop Test on filled pouches
Kerosene:
Copper Strip Corrosion
Density at 15° C.
Distillation recovery
Final boiling Point
Flash Point
Smoke Point
At the end of the three-month storage stability testing, Indian Institute of Packaging has given a test report, the salient features of which are summarized below:
A. Results of Test Performed on Film:
B. Results of Test Performed on Exposed Pouches
Appearance
Haziness of pouch material increases in the following order
Exposed to ambient conditions of temperature and Relative Humidity—Minimum Haziness
Exposed to 45° C. temperature—Moderate Haziness
Exposed to 45° C. temperature & 75-80% relative humidity—Maximum Haziness
2. Leakage Test
Exposed to ambient conditions of temperature and Relative Humidity—No leakage
Exposed to 45° C. temperature—Slight leakage from seal of one pouch each at the end of 1st week and 12th week.
Exposed to 45° C. temperature & 75-80% relative humidity—Slight leakage from seal of one pouch in the 1st week.
Seal Strength
The seal strength pattern showed that there is some erosion of sealing strength upon continued storage of the pouch. However, the seal strength at the end of 14 weeks itself was found to be sufficient to serve the purpose which was further confirmed by the drop test results. This factor has been adequately taken into consideration at the time of finalizing the specifications of the pouch at the end of the present study.
Kerosene Quality
It was observed that the kerosene quality did not undergo any appreciable change during accelerated storage testing and remained within its specifications. The pouch-kerosene compatibility has been found to be excellent in all the three conditions of accelerated storage stability test conducted under most severe test conditions at Indian Institute Of Packaging, Mumbai.
Conclusions Based on Studies of IIP, Mumbai
Based on the studies conducted in accelerated storage stability testing of filled kerosene pouches, Indian Institute of Packaging's test report gives following conclusions:
Pouch material selected for packaging of kerosene is found to be acceptable with respect to the parameters tested i.e. for appearance, strength, permeability etc.
The product-package compatibility found to be okay.
From storage studies carried out at accelerated and ambient conditions it is found that pouch is suitable for shelf life of maximum 3 months.
5.2.4.3 Lone Duration Stability Testing
Followed by the accelerated storage study testing done by IIP, Mumbai, the pouches stored in the Packaging Lab of IOC R&D Centre, Faridabad; were further got tested after the end of 10 months and 12 months respectively from IIP, Mumbai, for their performance related properties. Following is the summarized test results of all the testing carried out on pouches:
6. Final Specification of 1 Litre Kerosene Pouch
| Number | Date | Country | Kind |
|---|---|---|---|
| 2699/DEL/2006 | Dec 2006 | IN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IN2007/000453 | 10/3/2007 | WO | 00 | 6/17/2009 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2008/075375 | 6/26/2008 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5401546 | Meattle | Mar 1995 | A |
| 6500559 | Hofmeister et al. | Dec 2002 | B2 |
| 6599639 | Dayrit et al. | Jul 2003 | B2 |
| 20010010846 | Hofmeister et al. | Aug 2001 | A1 |
| 20030017352 | Dayrit et al. | Jan 2003 | A1 |
| 20090304959 | Srivastava et al. | Dec 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 9730847 | Aug 1997 | WO |
| 02074537 | Sep 2002 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20090304959 A1 | Dec 2009 | US |
