DISPERSION EN PHASE SOLIDE ET TRAITEMENT DE MICRO ET NANO-FIBRES CELLULOSIQUES EN PHASE PLASTIQUE POUR LA FABRICATION DE PRODUITS BIO-NANOCOMPOSITES D'INTERET COMMERCIAL

SOLID PHASE DISPERSION AND PROCESSING OF MICRO-AND NANO-CELLULOSIC FIBRES IN PLASTIC PHASE TO MANUFACTURE BIO-NANOCOMPOSITE PRODUCTS OF COMMERCIAL INTEREST

Abrégé français

Les tiges de plantes sont des ensembles de nanofibres de cellulose dun diamètre situé entre 10 et 70 nm et de longueurs de milliers de nanomètres. Le rendement mécanique des nanofibres de cellulose est comparable à celui dautres matériaux dingénierie comme des fibres de verre, des fibres de carbone, etc. Dans la présente invention, un nouveau procédé a été élaboré pour disperser des microfibres et des nanofibres cellulosiques à létat solide dans une matrice de plastique fondu ou dans un système de résine à base deau de faible viscosité en phase aqueuse. Linvention concerne la fabrication de bio-nanocomposites de rendement élevé en dispersant des microfibres et des nanofibres cellulosiques dans une matrice en plastique en utilisant de léquipement de traitement en plastique traditionnel. La présente invention surmonte également un défi unique de la transformation du bio-nanocomposite, qui consiste à les rendre commercialement viables en modifiant la surface de microfibres et de nanofibres dérivées de ressources renouvelables.

Abrégé anglais

Plant stem are bundles of cellulose nanofibers with a diameter ranging between
10 to 70
nm and lengths of thousands of nanometers. The mechanical performance of the
cellulose nanofibers is comparable to other engineering materials such as
glass fibers,
carbon fibers etc. In this invention a novel process has been developed to
disperse
cellulosic microfibres and nanofibres in solid phase into a molten plastic
matrix or in a
low viscosity water-based resin system in aqueous phase.
Invention relates to manufacturing Bio-nanocomposites of high performance by
dispersing micro-and nano-cellulosic fibres into plastic matrix using
conventional plastic
processing equipment. This invention also overcomes one unique challenge of
bio-nanocomposite
processing, which is to make them commercially viable by surface
modifying cellulosic micro-and nano-fibres derived from renewable resources.

Revendications

CLAIMS
Claim 1: A process to deposit films from a liquid phase of the cellulosic
micro and
nanofibre obtained from wood, root and nonwood sources, wherein said
cellulosic micro
and/or nanofiber is dispersed uniformly in a plastic which is soluble in the
above liquid
phase, drying the micro-and /or nanofibre film followed by cutting or shaping
the micro-
and/or nanofibre dispersed plastic film into small sized flakes, granules or
pellets and
then further incorporating this micro-and/or nanofibre dispersed plastic in a
molten
thermoplastic by using extrusion, high shear mixing or injection compression
process,
thereby giving a novel process to obtain a bio-nanocomposite product without
any risk of
agglomeration of micro-and /or nanofibers in the plastic matrix during their
melt mixing
process.
Claim 2. A process as cited in claim 1, whereby the liquid phase is selected
from
materials obtained from forest, petroleum and agro-based resources
representing group of
thermoplastics of polyvinyl alcohol, polyolefins, vinyl polymers and
copolymers,
engineered plastics selected from styrene-acrylonitrile copolymer (SAN),
nylon,
polyester, ABS/PC, and bio-based plastics comprising thermoplastic starch,
polylactic
acid (PLA), and poly-hydroxy-alkonates (PHAs).
Claim 3. A process as cited in claim 1, wherein the resulting PVA bio-
nanocomposite
reinforced with soybean stock nanofibers has demonstrated at least 4-5 fold
increase in
tensile strength compared to untreated fibres, whereas PLA nanocomposites
experienced
25% enhancement in tensile strength.
Claim 4. A process as cited in Claim 1 wherein the micro and nano-fibres are
dispersed
in surface active oligomers or polymers.
Claim 5. A process according to Claim 4, characterized in that the surface
active
oligomers or polymers are from the group of styrene copolymers and their
derivatives,
polyethylene glycol ¨maleic anhydride, styrene-maleimide, and ethylene-acrylic
copolymers in soluble liquid phase.
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Claim 6. A process as cited in Claim 1 wherein the liquid phase dispersed
micro and/or
nano fibrils are incorporated in liquid thermoplastic or thermosetting
polymers.
Claim 7. A process according to Claim 6, characterized in that thermoplastic
or
thermosetting polymers belong to unsaturated polyesters, vinyl esters, epoxy
or polyol-
isocyante resins and in which at least one of the components of these resins
are obtained
from renewable crop sources of soy bean, canola, corn, sunflower, palm, peanut
or any
other oil and their derived chemical precursors.

Description

CA 02549844 2016-05-17
DESCRIPTION
Background of the Invention
Cellulose micro- and nano-fibres are entangled in solid phase and are hard to
obtain in
individualized form due to strong hydrogen bonding. In aqueous phase and in
dilute
solution they can be obtained in highly dispersed form. Therefore, one
possible
method could be dispersing cellulose micro-and nano-fibres in aqueous or in a
phase
containing right combination of hydrophilic-hydrophobic character, typically a
water-
alcohol mixture phase an then solubilizing a polymer that has film-forming
property as
well as are soluble, either in an aqueous phase or in a mixture of water and
other
solvent in which, those micro-and nano-fibres can be dispersed.
Summary of the Invention
In this invention cellulose microfibres or nanofibres isolated from agro-
residues1'2
such as wheat straw, soy straw, bagasse, wood pulp, recycled fibre, root
fibres are
dispersed in water or in a mixture of water and alcohol, in a concentration
range 0.5 to
5% and a soluble polymer in the given mixture has been added. Mixture were
stirred with
or without temperature to dissolve the polymer completely and then casted into
film by
an efficient drying process. Films, thus produced are cut into small chips and
added in a
twin screw extruder to further disperse them in plastics in molten phase by
introducing
solid thermoplastic polymer in the extruder along with the dispersed film
particles.
The uniqueness of the invention is as follows:
This process avoid handling of liquid or water during conventional
nanocomposite processing by extrusion, compression, injection and other
molding
processes by introducing a masterbatch of pre-dispersed nanofibre in polymer
of high or
low molecular weight subsequently taking out excessive liquid by filtration,
drying or
casting.
The second unique aspect of the invention is to pre-disperse cellulosic micro-
and
nano-fibres into a polymer in solution phase that are having surface energies
compatible
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CA 02549844 2016-05-17
=
to base polymers in which they are further dispersed during their solid-phase
dispersion.
For example, acrylic and maleic derivatives of ethylene or vinyl backbone are
good for
their dispersion in polyethylene.
Extruded products are obtained in different shapes and sizes including
profiles,
sheets, rods, solid or hollow. Extrusion also includes pellet form of the
mixed
composition and then further using them for compression molding, blow molding,
injection molding, thermoforming, rotomolding. This method of liquid phase
casting
followed by solid phase mixing provided a unique method to manufacture bio-
nanocomposites.
This process of manufacturing bio-nanocomposite in solid phase is unique
because it solves the micro-and/or nanofibre dispersion problem in solid or
molten phase
compounding of plastics with those fibres.
Typical examples of plastic phase could be any thermoplastic materials
including
those obtained from forest, petroleum and agro-derived sources. Typically,
polyvinyl
alcohol, polyolefins, vinyl polymers and copolymers, engineered plastics such
as styrene-
acrylonitrile copolymer (SAN), nylon, polyester, ABS/PC, bio-based plastics
such as
thermoplastic starch, polylactic acid (PLA), poly-hydroxy-alkonates (PHAs).
Typical examples are cited below:
Example 1:
Polyethylene glycol-maleic anhydride treatments increased cellulose content of
soybean stock nanofibers from 40% to 60% when they are first filter deposited
or casted
into films and then these dispersed nanofibre films were introduced in molten
PVA
during extrusion, injection or high shear mixing . Nanofibers reinforced PVA
films
demonstrated at least a 4-5-fold increase in tensile strength, as compared to
the untreated
fiber/PVA film. In solid phase nanocomposites, improved mechanical properties
were
achieved with coated nanofibers. Typically, polylactic acid (PLA) having
initial tensile
strength 52 MPa was increased to about 65 MPa by introducing 3-4% of soybean
stalk
derived nanofibres.
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CA 02549844 2016-05-17
Example 2:
In yet another example, hemp nanofibre dispersed in ethylene acrylate olegomer
by casting process has been dried, chopped into flake and granules for easy
introduction
in high shear mixer, injection machine and extrusion, were melt-mixed with
polyethylene
and maleated polyethylene as an interface modifier improved tensile strength
of the
resulting nanocomposite by 50% and improved modulus by three folds.
Typical examples of plastic phase could be any thermoplastic materials
including
those obtained from forest, petroleum and agro derived. Typically, polyvinyl
alcohol,
polyolefins, vinyl polymers and copolymers, engineered plastics such as
styrene-
acrylonitrile copolymer (SAN), nylon, polyester, ABS/PC, bio-based plastics
such as
thermoplastic starch, polylactic acid (PLA), poly-hydroxy-alkonates (PHAs).
Example 3:
In yet another process these micro-and/or nanofibres from natural origin
are dispersed in surface active oligomers or polymers ( styrene copolymers and
their
derivatives, polyethylene glycol ¨maleic anhydride, styrene-maleimide ,
ethylene-acrylic
copolymers) in an aqueous or in a solvent phase in which these surface active
agents
polymers or oligomers are soluble. The liquid phase dispersed micro-and/or
nano fibrils
are then incorporated in a liquid thermoplastic or thermosetting resins
including bio-
resins ( such as polyesters, vinyl esters, epoxy or polyol-isocyante resins or
in which one
or all components of these resins are made from crop sources such as soy bean,
canola,
corn, sunflower, palm, peanut or any other oil or their derived chemical
precursors),
thereby partly or totally eliminating issues related to agglomeration of those
micro-and/or
nanofibres in the liquid resins during their solidification process.
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