Note: Descriptions are shown in the official language in which they were submitted.
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A PROCESS FOR PREPARATION OF BIODEGRADABLE BIOCOMPOSTABLE
BIODIGESTIBLE PEPLENE POLYMER
FIELD OF INVENTION
This invention relates to a biodegradable biocompostable biodigestible plastic
and a process
for preparation thereof.
BACKGROUND/PRIOR ART
Plastics are manufactured from petroleum namely polyethylene's,
polypropylenes, which
takes several years to degrade in the environment and therefore pollute water,
soil and air.
Environmental degradation of synthetic polymers =occurs at varying rates and
to varying
degrees depending on the characteristics of polymer and its environment. Such
degradations
are catalyzed by light, heat, air, water, microorganisms, and mechanical
forces such as wind,
rain, vehicular traffic, etc. Enhancing the stability and/or the degradability
of polymers is
generally accomplished by additives, changing the polymer backbone,
introduction of
functional groups, or by blending with appropriate fillers to make the
polymer/plastic material
from hydrophobic to hydrophilic material. However, many of these techniques
for
degradation also result in detrimental properties for the polymer products.
Petroleum based synthetic polymers/plastics to overcome the problems and limit
of natural
material owing to its excellent physical properties, light weight and cost
effectiveness,
plasticity is one of the modern scientific characteristics established by
developing various
hydrophilic polymers, especially hydrophilic plastic. However, each country in
the present
world is preparing for diversified counter measures as pollution problems from
numerous
plastic products are globally getting serious and it becomes a challenging
matter to solve such
pollution problems arising out of plastic wastes.
Recycling, incineration and landfill have been mainly used to solve these
environmental
pollution problems caused by various solid wastes, including plastic. However,
disposal of
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wastes through landfill as well as recycling cannot solve the environmental
pollution
problems completely owning to its inherent problems.
Accordingly, great interest and studies on development of biodegradable and/or
biocompostable plastic which can degrade itself at the life cycle end are
increasing recently.
The technology on degradable plastic is divided into photodegradable, oxo-
degradable, oxo-
biodegradable, biodegradable, bio-photodegradable and a combination of photo-
and/or oxo
and/or biodegradable plastic formulation technologies which are increasing
recently on the
industrial scale of manufacturing.
While there are many kinds of biodegradable plastic, for example microorganism
producing
polymers like PHB (poly-f3-hydroxybutylate), polymers using microorganism
producing
biochemical, or polymers having natural polymer like chitin or starch. The
problems which
are concerned with the present technology about polymers having various
additives such as
starch have been mentioned and improvements are described in the literature.
U.S. Pat. No.4, 021,388 by G. J. L. Griffin is directed to a process for
preparing biodegradable
film improved by treating the surface of starch with silane coupling agent to
be hydrophobic,
but it only increases physical interacting strength a little between matrix
resin and starch.
However, it has difficulty to solve the problem of degradation in the physical
properties of
films upon incorporating starch.
While U.S. Pat. Nos. 4,133,784 and 4,337,181 filed by F. H. Otey et. al. of
USDA disclose
processes for preparing biodegradable films by adding a-starch to ethylene-
acrylic copolymer.
It has difficulty to generalize for the high price of ethylene-acrylic
copolymer and lowering of
physical properties of the produced films.
Korean Patent Publication Nos.90-6336 and 91-8553 filed by Seonil Glucose Co.,
Korea are
related to processes for increasing physical interacting strength between
matrix resin and
starch by increasing hydrophobic property of starch or increasing hydrophilic
property of
matrix resin to increase compatibility with matrix resin and starch.
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US patent 5281681A describes photodegradable and biodegradable polyethylene
formulation
by co-processing ethylene and 2-methylene-1,3-dioxepane (MDOP) to produce
terpolymer
which exhibits better photodegradability than the copolymer, because the
additional carbonyl
groups in the polymer cleave upon absorbing light such as sunlight or UV
light. The
terpolymer can be both photodegradable and biodegradable because both the
ester and the
carbonyl functionalize.
US patent 5461094A describes biodegradable polyethylene composition chemically
bonded
with starch and a process for preparing thereof.
Therefore, it is required to provide high yield Peptide-polyethylene herein
referred to as
PEPlene, having good biodegradability/biocompostability/biodigestion in the
environment.
OBJECTS OF THE INVENTION
An object of this invention is to propose a biodegradable biocompostable
biodigestible plastic
and a process for preparation thereof which overcomes disadvantages associated
with the
prior arts.
Another object of this invention is to propose a biodegradable biocompostable
biodigestible
plastic and a process for preparation thereof which improves polymer
biodegradability/biocompostability/biodigestion without the loss of physical
strength,
structural characteristics and also being recyclable in the main recycling
stream should the
opportunity arise without affecting the stream.
Further object of the present invention is to propose a biodegradable
/biocompostable
/biodigestible plastic and a process for preparation thereof which is cost
effective.
Yet another object of this invention is to propose a biodegradable
/biocompostable/
biodigestible plastic and a process for preparation thereof which is
environment friendly.
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SUMMARY OF INVENTION
The present invention proposes Biodegradable! Biocompostable /Biodigcstible
plastics or
polymer products such as market carry bags, mulch film for agricultural use,
packing films
etc., to name a few plus replace the normal petroleum source plastics by
incorporating
biodegradable/biocompostable/biodigestible additives in the polymer processing
to render
them biodegradable/biocompostable/biodigestible. Thus, a plastic formulation
has been
developed by incorporating natural peptides/enzyme/protein from edible source
to make non-
biodegradable petroleum based polymers namely the polyolefin such as
polyethylene,
polypropylene and their different grades as Biodegradable/Biocompostable
/Biodigestible
polyolefin polymer.
Thus the present invention describes a
biodegradable/biocompostable/biodigestible film
prepared by chemical bonding of peptides/enzyme/protein and other additives
with an
example of polyethylene chains, which is a polyolefin having the most widest
general
application, and a process for preparing thereof The same can be the process
technology for
the other polyolefin's such as polypropylene etc.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing
description when read in conjunction with the accompanying drawings of
exemplary
embodiments of invention and wherein:
Fig.1: Environmental Biodegradation of the PEPlene film.
Fig.2: 150 Days Environmental Soil Biodegradation of the PEPlene film.
Fig.3: FTIR indicating the peptides/enzyme/protein incorporation in the
PEPlene
Master Batch.
Fig.4: FTIR indicating the peptides/enzyme/protein incorporation in the
PEPlene film
Fig.5: PEPlene Percentage Degree of Biodegradation
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DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
The instant invention makes a disclosure in respect of biodegradable
biocompostable
biodigestible plastic and a process for preparation thereof.
Accordingly, the Present invention provides a process for composition and
composition
thereof for accelerating the biodegradation/biocompostability/ biodigestion of
PEPlene
materials.
The process comprises preparing a composition by combing at least one peptide
with at least
one protein and enzyme, and a composting agent. This is followed by blending
with at least
one polymer in the presence of additive preferably at a temperature of 45-300
C so as to
retain the essential catalytic properties and nature of the
peptides/enzyme/protein.
The composition thus obtained can be directly used or encapsulated in a
polymer constituting
a coated composition or in liquid form. Various examples of above ingredients
can be listed
herein below:
Peptide ¨ cellulase, papain, but not restricted to the examples herein.
Protein/enzyme - milk, vegetable. (Soya bean, lady finger). But not restricted
to the examples
herein.
Composting Agent ¨ carboxy methyl cellulose, hydrolyzed mutton tallow. But not
restricted
to the examples herein.
Polymer ¨ polyethylene, which can be at least one of linear low density
polyethylene
(LLDPE), high density polyethylene (HDPE), low density polyethylene (LDPE)
medium
density polyethylene, ethylene vinyl acetate (EVA) and ethylene butyl acrylate
(EBA) and
any combination thereof.
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Additive- citric acid, lactic acid bacillus, hydrolyzed mutton tallow, yeast
and any
combination thereof to improve biodegradation/ biocompostability/ biodigestion
properties of
polymeric material.
The natural components of the composition of the present invention are food
grade materials.
This can also include other carbohydrates such as lactose, starch etc.
The present invention leads to reduction in production cost owing to
simplification in the
process for preparation of the composition. It avoids the problem of
degradation in the
physical properties of film by enhancing solely physical interacting strength
between matrix
resin and peptides/enzyme/protein and added additives referred above.
Further according to another embodiment, a biodegradable/biocompostable
/biodigestible
polyethylene composition can be chemically bonded with starch.
The composition of PEPlene has molecular weight of at least about 7000 with
good
biodegradable/ biocompostable/ biodigestible characteristics fig. 1.
In plastic polymer, x, y and z in space integers of the peptide/ enzyme /
protein groups such as
carboxyl are randomly or uniformly distributed in the polymer along the
backbone of the
polyethylene polymer, according to the varying concentrations of the
functional groups
Figure 3 and 4.
The blend of plastic composition is subjected to extrusion at a temperature of
about 100 -
350 C. So that during the extrusion process, the composition infuses or
penetrates into the
cells or molecular structure of the polymer while the polymer is in a pre-
molten state. The
plastic products obtained from the present process include secondary
packaging/plastic films,
vest bags, bin liners, rubbish bags, agricultural mulch, and many other types
of films. The
present blend of composition is also suitable for the polymers e.g. 3D
printing, fiber spun, and
nonwoven material using injection molding and melted spun process technologies
to name a
few.
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The mechanisms of biodegradation may include the following stages:
Action: Peptide/ enzyme / protein help to introduce the hydrophilicity in the
chains of the
polymer. While the polymer is in the pre-molten state during the process of
extrusion the
Peptide/ enzyme / protein penetrates into the polymer so as to enable the
hydrophilicity in the
polymer formulation.
Thermal degradation: The hydrophilic nature polymer is processed further into
a polymer
film which undergoes a thermal degradation or breakdown into smaller
fragments, under
laboratory conditions this takes place due to temperature conditions and the
moisture in the
environment and also due to light and oxygen.
Soil action: After thermal degradation (either in laboratory conditions or in
the natural
environment) the presence of peptide/ enzyme /protein in the composition of
the present
invention due to hydrophilic nature attracts soil microorganisms which attack
the polymer.
Inherent moisture in the polymer formulation due to hydrophilicity of the
composition and/or
moisture in the soil (for example 58% moisture) enables the chain links of the
polymer,
already in a separated or weakened molecular state, to undergo a natural
composting process
wherein the products of depolymerisation provide nutrients for the soil
microorganisms and
the remaining products to become biomass.
Degradation: The ultimate products of biodegradation include carbon dioxide
and water due
to the microbial metabolism of the polymer.
In one example, the enzyme compositions of the present invention are blended
with a
pulverized co-polymer i.e. LLDPE. Polyethylene used for the manufacturing of
films for
secondary packaging like vest bags, bin liners, rubbish bags, agricultural
mulch films need the
co polymer LLDPE both for elasticity and scalability of the film. The presence
of peptide/
enzyme /proteins and other additives in the polyethylene attracts the soil
microorganisms to
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act on the composted material. The residue is biomass, water and carbon
dioxide. However, in
the present PEPlene polymer the biodegradation residues are carbon dioxide and
water.
Other products resulting from biodegradation or bio-refining include gases
(e.g. Methane),
Ketones (e.g. Acetone) and alcohols (e.g. Methanol, Ethanol, Propanol, and
Butanol).
Products such as Methane and Ethanol are known sources of energy and it is
envisaged that
these, or other resulting products, may be captured for further use, such as
to act as energy
sources.
One advantage of the present invention is that the polymer products obtained
by the present
invention retain the desired mechanical properties and shelf life plus
recycling of polymers
equal to the non-biodegradable polymer ¨ example polyethylene. Unlike the
photo-oxidative
or oxodegradable agents which initiate the degradation of the Polymer
spontaneously and
their-by reduce the shelf life of the polymer products, enzymatically
initiated biodegradation/
biocompostability/biodigestion process begins only upon exposure to microbes
in the
environment as life cycle end.
The PEPlene films prepared using the peptide/ enzyme /protein composition
either by directly
dispersed or encapsulated in the present invention have been successfully
tested as per ASTM
D 5988, ISO 14855, ISO 17556 and EN 13432/ ASTM D6400 (and other national
equivalents) test protocols for bio degradability and Eco toxicity and plant
germination
capability of the soil in which these films biodegrade. For example, EN
protocols for cellulose
based products require greater than 90% degradation within 180 days. Products
according to
the present invention start to degrade from 90 days under composting
conditions Figure 1
and 2. Speed of degradation is generally affected by environmental microbial
conditions, the
amount of peptide/ enzyme /protein composition and the thickness of the
product. By way of
example, degradation of products prepared according to the present invention
has been
achieved with extruded film of 5 ¨ 50 microns thickness.
Accordingly, a further advantage of the present invention is that the
compositions comprise
natural and food grade materials and leave no toxic residues after
biodegradation and/or are
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within the heavy metal limits as prescribed by various countries for the
plastic
material/products.
The present invention product is also recyclable in accordance with ASTM D
7209 protocol
and EN 15347; The present invention product is also compostable according to
standard EN
13432; and biodegradable according to standards ASTM D 5988, ISO 14855, ISO
17556 and
EN 13432/ ASTM D6400 (and other national equivalents) test protocols for
biodegradability
Figure 5.
Also, the present invention evaluated under US FDA 177.1520 for food contact
safety
compliance.
A further advantage of the present invention is that the materials prepared
according to the
invention biodegrade when subjected to suitably environmental conditions. The
product
PEPlene films of the present innovation are also stable until disposal, such
as into soil,
compost, landfill, bio-digester or the like and under anaerobic conditions.
The materials are
able to be metabolized into biomass by the colony forming bacterial groups
present in the
compositions of the present invention and the microorganisms available in the
soil.
The compositions of the present invention with polyolefin such as polyethylene
under aerobic
conditions have shown that it is possible to subject poly films to complete
biodegradation and
bio-compostable by oxidative microbial attack.
It is to be noted that the present invention is susceptible to modifications,
adaptations and
changes by those skilled in the art. Such variant embodiments employing the
concepts and
features of this invention are intended to be within the scope of the present
invention, which is
further set forth under the following claims:-
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