Note: Descriptions are shown in the official language in which they were submitted.
CA 02253060 1998-11-20
_..'.i~ENTIR!
Page 1 of 25
From: Dr. Raj N. Pandey
CHEMISAR LABORATORIES INC.
248 Silvercreek Parkway N.
Guelph, Ontario, Canada
N1H lE7
Phone: (519) 836-2313
(519) 836-5023
Subject: New Patent Application in Canada
Title: ENVIRONMENTALLY FRIENDLY BEVERAGE
CONTACT LAYER OF THERMOPLASTIC
TUBING
Inyentors . Raj N. Pandey, Rupesh N. Pandey and Terry L. Jackson
Asslgtlee . Dr. Raj N. Pandey
Replication No.
CONTENT : Draft Application, including:
o Abstract of the Disclosure,
o Specification,
o Claims,
o Formal drawings,
o Formal documents
November 19, 1998
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BACKGROUND OF THE INVENTION
The thermoplastic tubings used in beverage industry must be non-permeable so
as not to cause
contamination or become contaminated when in close proximity of other liquids
or beverages.
The tubing used for example to transfer syrup or carbonated beverages must not
impart taste or
odour to the beverage material and must not be susceptible to stress cracking.
The tubing must
be environmentally friendly and should not contribute any possible inorganic
or organic
contaminant to the beverage contained or flowing through it. Ideally such a
tubing should be
economically viable and environmentally friendly in that the water or
beverages contained in it
do not get contaminated. lf, for example, water meeting drinking water
criteria of U.S.
Environmental Protection Agency (U.S. E.P.A.) or drinking water Objectives of
Ontario, Canada,
is passed through the tubing the test results before passing and after should
be the same.
Unfortunately, the plastic tubings in current practices suffer from self and
cross contamination
problems mainly due to permeability and transmission properties which alters
the taste, odours
and sometimes on long term may pose a safety problem to human health. The
other problems
of lesser importance are related to carbonated beverages in which dissolved
carbon dioxide is
found to permeate through the tubing and thereby lowering the carbon dioxide
content in the
beverage.
The phenomena of the environmental problem which is getting prominent
recognition in recent
years over the world in general, as well as in Canada, and the U.S. in
particular pertains to
health. The scrutiny is related to the transmittance of volatile organics (C,
to C,o hydrocarbons)
from the solid tube composed of thermoplastic polymeric material to the liquid
it contains. Such
materials may or may not contribute to taste and odour problem and therefore
may not be
CA 02253060 1998-11-20
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perceived by humans by sensory mechanism. In carefully designed experiments,
GC/MS analysis
performed of air samples collected by evacuation or pressure differential
techniques on many
tubes currently in use for beverage dispensing industries, have found them to
contain
hydrocarbons. When the empty tubes are purged with inert gases such as Helium
or Nitrogen
and the stream is analyzed by the techniques of GC/MS, hydrocarbons are found
in the stream.
When a typical tube is filled with distilled water and allowed to stand at
room temperature and
the water is analyzed by the technique of GC/MS, hydrocarbons are often
detected. The source
of these hydrocarbons are related to the polymeric thermoplastic material
itself and they were
most likely formed during heating and melting of the polymer in the extrusion
of the tubing and
remained captured during and after cooling. The volatile organic materials
formed in the molten
state of the polymer resin and held in the tube are able to diffuse through
the tubing's inner layer
and contaminate the beverages in contact with it. This phenomenon is found
with most tubing
manufactured from polyethylene and related materials. Polyethylene and related
materials, with
the exception of these environmental drawbacks, are low cost materials and
meet various other
attributes of the tubing materials and therefore have been marketed
economically and
predominantly.
In recent years considerable attention has been given to solving this problem.
Tubing made of
alternative materials such as fluorocarbon, nylon, polypropylene, saran etc.
have certainly added
improvements and have shown a performance advantage with regards to the
transmission and
diffusion of flavours. However there is a loss of flexibility of the tubing.
Additionally, the cost
is of the order of three to four times higher. Furthermore, fluorocarbons have
high softening
points (320°C). This property not only makes it difficult to extrude
but is also an energy
intensive process. While very tough, translucent fluorine containing polymer
always carnes a
potential concern of the formation of corrosive HF gas in a molten condition
in the extrusion
CA 02253060 1998-11-20
process in contact with the other polymerrs containing carbon and hydrogen in
their molecules
such as polyethlene.
One preferred method of making beverage tubing which can offer a potential
solution to
circumventing the environmental problem is to incorporate an inner fluid
contact layer of
environmentally friendly and non-permeating materials. This inner layer can
then function as a
barner layer. The barner layer would thus provide environmental protection and
safety against
permeation of carbon dioxide, oxygen and contaminating volatile organic
hydrocarbons from the
outer layers. Due to the inert, odourless, non-soluble and non-permeable
nature of the inner
layer, the flavour and taste remain unaffected.
The making of a barrier layer with desirable properties has been the subject
of considerable
research interest and difficulty in the beverage dispensing industry.
Materials such as
fluorocarbon, nylon, Ethylene vinyl alcohol (EVOH) and polyvinyl chloride
(PVC) are now
commonly used. EVOH and nylons are found to lose with time, their vapour and
gas barrier
properties after exposure to water or increased humidity. Although polyvinyl
chloride itself is
safe, it is formed from vinyl chloride monomer which is carcinogenic.
Among the various known barriers in use, fluorocarbon ranks among the best in
regard to its
inertness and non-permeable properties. However, it is the most expensive.
There is another
recognized problem with tubing with a fluorocarbon or polypropylene inner
layer. These
materials are stiff which often require excessive force in clamping, which may
result in cutting
or cracking of the inner layer of the tubing and are extremely difficult to
bond to the other layers
of the tubing.
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Most recently, with the introduction of many new pungent flavours, it has
become increasingly
difficult to flush out a tube in order to change beverage flavours in a
dispenser system. With the
more pungent flavours such as root beer and cherry, it is virtually impossible
to remove the
absorbed flavour from current state-of the-art tubes.
Therefore, there exists a need for a simple, economically viable, and
contaminant free
thermoplastic tubing with an environmentally friendly inner barrier layer
which effectively
overcomes the inherent difficulties of stiffness, gas and flavour
transmission, and flushability
facing the beverage industry.
As follows, the present invention is considered to have overcome many of the
difficulties
discussed and offers a simple and economical solution to vapour and gas
transmission for a wide
range of applications.
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SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an efficient and
economical method
for making a novel barrier layer tubing for beverage applications and a novel
barrier film layer
for food packaging industries where the preservation of aroma, taste and
moisture transmission
is of paramount importance.
In accordance with the invention, there is thus provided a process for making
a tubing for
beverage dispensing which comprises of an environmentally friendly inner
layer, P.J.1, made up
of copolyester with molecular formula (C,oHg04) without any hazardous
ingredients. This layer
is bonded to the outer polyethylene layer by terpolymer, P.J.2, with molecular
formula (C~H,~O)°.
Applicant has found quite unexpectedly that by using carefully controlled
conditions an inner
layer P.J.1 can be efficiently bonded via P.J.2 to the non-compatible
polyethylene layer.
According to the invention, a three-layer tubing for beverages is provided.
The beverage contact layer of about 0.1 mm is formed from a first
thermoplastic material P.J.I
under careful extending temperature between 250-270°C, under the
atmosphere nitrogen or carbon
dioxide or a mixture of both which have passed through a proprietary filter
for achieving the
non-brittle property of tubing. In the preparation of the test films, the
preferred rate of reaching
said temperature was found to be 15°C per minute. A thin film of about
0.1 mm of terpolymer
material can then be coated by the art of extrusion at 150°C for
bonding the outer layer of about
1 mm of Polyethylene also at I50°C and at pressure of about 1000 psi.
The outer layer may be
either linear low density polyethylene, ethylene vinylacetate or any other
variety of thermoplastic
material suitability selected for the purposes of the outer layer which offers
the desired flexibility.
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g
The absence of stiffness, brittleness, and inertness with the other desired
attributes such as cost
makes P.J.1 a perfect non-permeable material of choice and makes this
invention to be so much
attractive.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present invention will be more apparent
from the
following description of a prefer ed embodiment as illustrated by way of
examples in the
accompanying drawings in which:
FIG. 1. is a view of the tubing for dispensing beverages in accordance with
one
embodiment of the invention.
FIG. 2. is a diagrammatic illustration of a film making in accordance with
another
embodiment of the invention.
FIG.3. is a diagrammatic illustration of experimental set-up used to perform
the
permeability test.
DETAILED DESCRIPT10N OF PREFERRED EMBODIMENTS
In the process which is schematically illustrated in FIG. 1 a tubing with
three layers is shown
for transporting beverage (BEV) through the tubing. Beverages are normally
dispensed through
several tubes in close proximity canying different beverages and syrup to the
dispenser. The
beverages may include colas, alcohols, carbonated and non-carbonated drinks,
and other liquid
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form drinks. The carbonated beverages are comprised of ingredients such as
syrup, and water
to which carbon dioxide has been added. ~ The syrup has the flavoring material
which may be
derived from natural fruit or synthetic materials. The carbon dioxide
solubility is normally
increased by pressure or by lowering the water temperature near freezing.
As shown in Figure 1 the beverage (BEV) flows through the inner layer of and
its taste and
odour are unaffected. The inner layer, P.J. l, is non-permeable, chemically
inert and perfectly
stable and therefore functions as a protective layer for the beverage
contained for dispensing.
The contaminating middle and outer layer are unable to transmit the organic
volatiles through this
low cost amazing barner.
As shown later by GC/MS analysis the barrier layer P.J.1 does not allow the
permeation of
various kinds of beverages through it including among them the very invasive
root beer. This
finding is in contrast to commonly used barriers layers which have been
discussed before.
According to embodiment of this invention the barrier layer, P.J.1 need not be
thick. In a typical
example P.J.1 can be about 0.10 mm or more, the P.J.2 layer about 0.10 mm or
more and the
outer layer about 1.0 mm or more. The strength of the inner layer is
sufficient to contain the
carbonated drinks under pressure and eliminating the blistering problem. Under
the processing
conditions of temperature and pressure, the inner layer does not suffer from
cracks and stiffness
as is common to the other materials. The processing and extrusion conditions
do not require any
significant modification to the capital and operational raw material costs of
the extrusion process
and therefore economically attractive in providing safe beverage dispensive
tubing by switching
to this inner layer.
To convert the tube for application in high pressure environments, yarn
reinforcement can be
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used as is known to the art. The following non-limiting examples further
illustrate the invention.
EXAMPLE 1
The elemental analysis of innerlayer, middle layer and outer layer materials
were performed for
material balance using Carlo Erba instrument. The carbon and hydrogen analysis
was performed
by combusting a known weight of sample at 1000°C in the presence of O2.
The resulting gases
namely COZ and H20 produced were determined by standard techniques of gas
chromatography.
The percentage Carbon and Hydrogen in the samples of materials were calculated
from the
combustion of NBS Standards. The Oxygen analysis was performed by the
pyrolytic technique.
The elements such as N, S and halogens were not detected. As can be seen from
the results in
Table 1 there was a good mass balance within the experimental error. These
results indicate that
the composition of the materials used contain carbon, hydrogen and oxygen only
and that there
is good agreement between theorical and experimental values.
TABLE 1
Composition by
Weight
Elements Inner Layer FoundMiddle Layer Outer Layer Found
Found
C 62.44 (62.50)* 75.03 (75.00)* 85.78 (85.71
)*
H 4.16 (4.16) 12.60 ( 12.50) 14.37 ( 14.28)
O 33.46 (33.33) 12.48 ( 12.50 - -
Total I 100.06 I 100. I 1 I 100.15
* Values in brackets are calculated expected values.
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EXAMPLE 2
A thin film P.J.I of polyester of formula (C~oHeO4)~ in range of thickness of
about O.l mm to
about 0.5 mm were prepared in the laboratory as shown in Figure 2. In this
method the
polyester, P.J.1 in pellet form is uniformly spread over bottom die and the
top die is placed on
it. The die/P.J.1/die set is protected from the flowing stream of nitrogen
which has been
pretreated in passing through PJD and purges the entire system of GC oven
which is programmed
to increase linearly from room temperature to 320°C at rate of
15°C per minute. Once the
temperature on the thermocouple is recorded to about 270°c the die set
is taken out and pressed
immediately to about 1000 psi or sufficient to the thickness of the film
required. The thickness
of the film can be controlled by applied pressure. The die set is cooled in
water and film
removed for testing. Such a processing condition of temperature and inert
atmosphere is
necessary otherwise the film produced becomes brittle and does not conform.
A group of five films produced in this way were immersed in distilled water
and contents boiled
in a beaker for an hour and cooled to room temperature and the water with the
film in it kept for
7 days then the water was analyzed by Inductively Coupled Plasma for various
metals. The
anions were analyzed by standard technique of Ion Chromatography. The results
are presented
in Table 2. These results indicate that the film P.J.1 does not add any
impurity and water
remains unaffected and meets the drinking water criteria as shown in Table 2.
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TABLE 2
Sample Water
Parameter TestedExtract with P.J.1MAC* (mg/L)
Film concentrations
(mg/L)
Aluminum N.D. 0.10
Arsenic N.D. 0.025
Barium N.D. 1.0
Boron N.D. 5.0
Cadmium N.D. 0.005
Chromium N.D. 0.05
Iron N.D. 0.30
Nickel N. D. 0.01
Lead N. D. 0.0 I
Mercury <0.001 0.001
Manganese N.D. 0.05
Selenium N.D. 0.01
Uranium N.D. 0.10
Nitrite (as N) <0.1 1.0
Nitrate (as N) <0.1 10.0
N.D. = Not Detected Detection limit - 0.005 mg/L
** MAC = Maximum Acceptable Concentration as a Drinking
Water Objective - Health Related
EXAMPLE 3
In another experiment a second batch of P.J.1 films were kept immersed in
distilled water for a
period of 2 weeks. The water was then analyzed for organic volatile impurities
by technique of
GC/MS using Hewlett Packard GC/MS with Tekmar Purge and Trap. The results are
presented
in Table 3. These results clearly indicate that the film P.J. I does not
impart any organic volatile
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impurity and that the water remains unaffected to its original environmental
state.
TABLE 3
Parameters Extract Sample Maximum Drinking
Water with P.J.1 Water Limit
Concentrations Concentration
(m~-) (mg~L)
Benzene N. D. 0.005
Toluene N.D. 0.02
Xylene N.D. 0.30
Ethyl Benzene N.D. 0.002
Volatile OrganicsN.D. 0.01
TrichloroethyleneN. D. 0.05
Trihalomethane N.D. 0.35
N.D. = Not Detected (<0.001 mg/L)
EXAM PLE 4
The inner layer film, P.J.1, was prepared by the method described above and
was subjected to
permeability performance test. The apparatus shown in Figure 3 which is self
explanatory was
used. The film membrane is firmly placed as shown and it divides the cell into
two
compartments A and B. The transmittance of vapours and gases from A to B can
occur only
through the membrane. Septum 1 and Septum 2 are provided for withdrawal of
samples for
analysis by standard technique of gas chromatography.
In a typical water vapour transmittance determination experiments the
technique involved passing
of helium (or nitrogen) through a bubbler which contained water to humidify
the helium. By
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opening and closing of valves 1 and 2, the side A of the cell was saturated
with water vapour.
The side B was kept dry by flowing the stream of dry helium. The membrane was
allowed to
equilibrate with saturated water vapour for at least 24 hrs in a steady state.
The chromatographic
analysis for water both from Side A and Side B of the cell were performed. The
presence of
water was detected on Side A and not on side B. Even after creating
differential pressure by
lowering the pressure on Side B the water was not detected on Side B implying
that the film
membrane does not allow transmission of water vapour. Later helium was
replaced by carbon
dioxide and then oxygen and permeability experiments were repeated under
steady state
condition. Carbon dioxide and Oxygen were not detected on the Side B of the
cell. These
results are presented in Table 4 and indicate that the film membrane of P.J.1
does not transmit
water vapour, carbon dioxide and oxygen in contrast to polyethylene membranes
of the same
thickness or more and under identical conditions. Therefore the novel
polyester as an inner layer
is found to be an excellent barrier.
TABLE 4
Permeant Film MembraneTemp. ConcentrationConcentration
(barrier) (C) Permeant Sideof Permeant
on
A of Cell Side B of Cell
Water Polyester 23-24 Saturated N.D.
(P.J.1 )
COz Polyester 23-24 Saturated N.D.
(P.J.1 )
OZ Polyester 23-24 Saturated N. D.
(P.J.1 )
N.D. = Not detected
Polyester = Copolyester of formula (C,~H804)~
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l5
EXAMPLE 5
In another embodiment of experiments the water in the bubbler (Figure 3) was
replaced by
alcohol, acetone and pentane and steady state was allowed to attain. The
concentration of
permeant were measured by gas chromatography. The results of analysis clearly
showed that the
PET (P.J.1) membrane does not allow permeation of organic volatiles. These
results are shown
in Table 5. The P.J.1 is therefore a material of choice to prevent
transmission of organics.
TABLE 5
Permeant Film MembraneTemp. ConcentrationConcentration
(barrier) (C) of Permeant of Permeant
ambient Side A Side B
Ethyl AlcoholPolyester 23-24 Steady State N.D.
(P.J.1 ) Saturation
Acetone Polyester 23-24 Steady State N.D.
(P.J.1 ) Saturation
Pentane Polyester 23-24 Steady State N.D.
(P.J.1 ) Saturation
Pentane Polyethylene 23-24 Steady State Detected
Saturation
N.D. = Not Detected
Polyester = Copolyester of formula, (C~~,HRO4)n
EXAMPLE 6
In preferred embodiment, permeability measurements were carned out with actual
beverages
using Cola, Root Beer, Beer and Scotch Whisky. The apparatus of Figures 3 was
modified and
side A was saturated with each of the beverages and tested individually. In
steady state condition
the permeability results are reported in Table 6. In a separate study, the
widely used barrier
CA 02253060 1998-11-20
16
layers EVOH (ethylene vinyl alcohol), nylon-6 and nylon-11 have been found to
permeate to
some extent when methyl salicylate (a flavour component) was used as the
permeant. This
observation does not appear favourable in addition to the high cost of these
materials. The low
cost P.J.1 material with superior transmission properties is the most logical
choice put forward
by the virtue of this invention.
TABLE 6
ti
Permeant Film Temp Concentrationon
Concentra
Membrane (C) Permeant Permeant
ambient Side A Side B
Cola 1 Polyester 23-23 Saturated N.D.
(P.J.1 )
Cola 2 Polyester 23-24 Saturated N.D.
(P.J.1 )
Root Beer Polyester 23-24 Saturated N.D.
(P.J.1 )
Beer Polyester 23-24 Saturated N. D.
(P.J.1 )
Scotch WhiskyPolyester 23-24 Saturated N.D
(P.J. l
N.D. = Not Detected
Polyester = Copolyester of formula, (C,oHg04)~
EXAMPLE 7
For the application in beverages dispensing such as the tubing of this
invention, the tube must
preferably be washable or flushable with water. The disc of polyester was
soaked in two major
colas and Beer for 24 hours at room temperature. The treated discs were
successively washed
with 10 ml distilled water. The wash solutions were collected and analyzed by
GC/MS. 5 ml
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of wash samples were taken in Tekmar Purge and Trap system and analyzed by
Hewlett-Packard
GC/MS. The results of analysis presented in Table 7. These results indicate
that the film surface
is flushable implying that the surface adsorption is insignificant.
TABLE 7
Detection
in Wash
1 2 3 4 5
Cola Detected Detected N.D. N.D. N.D.
1
Cola Detected Detected N.D. N.D. N.D.
2
Beer Detected Detected N.D. N.D. N.D.
N.D. = Not Detected
EXAMPLE 8
Commonly used beverage dispensing tubings available in market were tested for
the release of
contaminating gases and vapours upon purging or creating pressure differential
by evacuation.
The P.J.I disc was tested by evacuation only.
Each experiment on commercial beverage tubing comprised of purging with helium
a certain
length of tubing by flowing a stream of helium through the inner layer of the
tube and analyzing
gases and vapours released upon purging by Purge & Trap / GC-MS technique. The
results are
presented in Table 8. As can be seen from the results of Table 8 the polyester
disc P.J.I does
not release any such contaminant and therefore environmentally safe.
CA 02253060 1998-11-20
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TABLE 8
Source Test Contaminants
of Method Found
Tubings
Commercial tubings Helium C, - C,o
currently used in marketPurge & Trap Hydrocarbons
for
Beverage Dispensing
Commercial tubings Evacuation C, - C,o
currently used in market Hydrocarbons
for
Beverage Dispensing
Copolyester (P.J.I Evacuation None
disc)
