CA2276987A1 - An impervious, economically viable and environmentally friendly thermoplastic tubing and film - Google Patents

Abstract

A layered tubing for use in beverage carrying and dispensing composed of a thicker outer layer, a thin intermediate bonding layer and the innermost impermeable and nonreactive barrier layer is disclosed.
This invention relates to a new and economically viable method for making a Thermoplastic Multilayer Tubing which is comprised of layer's in which the inner layer P.J.1 is a Barrier layer which does not allow the permeation and diffusion of vapours, gases, moisture; aroma and flavours. The P.J.1 layer which is totally inert, odourless, non-soluble in water, alcohols, beverages, syrups and alike is the beverage contact layer.
The P.J.1 is a copolyester with a general formula (C10H8O4)n without any hazardous ingredients and has a melting point range about 160°C and density between 0.9 and 1.0 g/ml.
In one construction, the P.J.1 layer is bonded to Ethylene Vinyl Alcohol (EVOH) by a bonding layer P.J.2 which is Polyethylene copolymer with modified polyolefin having approximately % C = 79.2, % H =13.6, %O = 7.6, with trace amounts of N, melting point range 104 - 138°C and specific gravity 0.91 - 0.95 (water = 1). The bonding material is chemically stable under the processing conditions.
The outer surface layer is comprised of polyethylene, P.E., with a general formula (C2H4)n having a melting point range of about 180°C. It is bonded to the EVOH
layer by P.J.3 which is modified polyolefin. This is referred to as the Class I tubing of this invention.
In another class of tubing, which is referred to as the Class II tubing of this invention, the outer surface layer is comprised of polyethylene, P.E., with general formula (C2H4)n having melting point range about 180°C. It is bonded to the impermeable P.J.1 layer by the P.J.4 layer which is a chemically stable plastic material under processing conditions, having a general formula (C8H16O)n, density of about 0.9, and melting point of about 55°C.
The applicants have developed processing conditions for the inner layer P.J.1, and a suitable method for making the beverage tubing and film which meet the attributes of desired tubing and film and solve the long standing problem of vapour and flavour transmission and adsorption in the transfer of flavoured beverages. The film form of P.J.1 can also find its application in the food packaging industry to prevent loss of moisture, flavour and taste. The realization is that P.J.1 is environmentally friendly for beverage holding and dispensing and is envisioned to have numerous potential applications now, and in the new millennium with increasing demand for such tubing. These applications can utilize the unique properties of the P.J.1 layer in an environmentally friendly and cost-effective manner.

Description

RELATED APPLICATION
This application is a continuation-in-part of Canadian Patent Application No.

2,253,060, filed on November 20, 1998 currently pending before the Canadian Patent Office.
FIELD OF THE INVENTION
The present invention relates to a tube or a hose for use with beverages and drinking water for holding, carrying and dispensing. More particularly, the present invention relates to a multilayer tubing (or hose) which can be employed in suitable applications where vapours, gases and liquids are not allowed to permeate through the barrier layer, thus, ensuring the integrity of the liquid contained within the W be.
BACKGROUND OF THE INVENTION
The thermoplastic tubing used in the beverage industry must be impermeable so as not to cause contamination or become contaminated when in close proximity with other liquids or to beverages. For example, the tubing used to transfer syrup or carbonated beverages must not impart taste or odour to the beverage 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 therein 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 become contaminated. If for example, water meeting the drinking water criteria of U.S. Environme;ntal Protection Agency (U.S. E.P.A.) or the 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 tubing in current practices suffer from self and cross contamination problems mainly due to permeability and transmission properties which may alter the taste, create odours and sometimes after long term exposure 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 environmental problems, 'which in recent years have received prominent to recognition worldwide, as well as in Canada and the United States, pertain to health. The scrutiny is related to the transmittance ofvolatile organics (C1 to Cio 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 problems and therefore may not be perceived by human sensory mechanisms. In carefully designed experiments, GC/MS
15 analysis performed on air samples collected by evacuation or pressure differential techniques from many tubes currently in use for beverage dispensing industries, has detected presence of hydrocarbons. When the empty tubes aJre purged with inert gases such as Helium or Nitrogen, and the stream is analyzed by the oechniques of GC/MS, hydrocarbons are found in the stream. When a typical tube is filled. with pure distilled water, allowed to stand at 2o room temperature, and the water is analyzed by the technique of GC/MS, hydrocarbons are often detected. The source of these hydrocarbons is related to the polymeric thermoplastic material itself and they were most likely foamed during the 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 disuse through the tubing's inner laryer and contaminate the beverages in contact with it. This phenomenon is found with most tubing manufactured today from polyethylene and related materials. With the exception of these drawbacks, polyethylene and related materials are low cost materials which meet various other attributes of the tubing materials such as shrinkage, elongation, stress-crack resistance and flexibility, and therefore have been predominantly marketed as economical tubing.
It is becoming increasingly important now .and for the new millennium that the tubing employed for beverage transport and dispensing be impervious to interaction with the materials present in the beverages such as Methyl Salicylate (CgHg03) present in Root Beer.
Additionally the tube must be fully inert when in contact with chlorinated city water and cleaning solutions such as Diversol~.
i 5 It is also imperative that the tube employed for beverage contact and dispensing be impervious to hydrocarbon contamination d.ue mainly to permeation through the tubing layers. It is anticipated that future Federal and State regulations in various countries will place more restrictive Threshold Limit Values (TLV) for such contaminants.
In recent years considerable attention has been given to solving the permeation problem.
2o Various types of tubing have been proposed rind used to address these concerns with partial success. In general, the most promising of these are multilayer tubes which employ a thick outer layer and the most important inner-most layer which is thinner and composed of material chosen for its ability to block the diffusion and permeation of concerned materials such as hydrocarbons. Tubing made of alternative materials such as fluorocarbon, nylon, polypropylene, 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 in the flexibility of the tubing: Additionally, the cost of some constructions may be four times higher than the Polyethylene products. Furthermore, fluorocarbons have high softening points making it difficult to extrude in an energy ef~'-lcient manner.
Although they are very strong, translucent fluorine-containing polymers always carry a potential concern of forming corrosive HF gas in a molten condition during the extrusion process while in contact with the other polymers such as polyethylene, containing carbon and hydrogen in their molecules.
One preferred method of making beverage cubing which can offer a potential solution to circumventing the environmental problem i:~ to incorporate an inner fluid contact layer of environmentally friendly and non-permeating materials. This inner layer can then function as a barrier layer. The barrier 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, insoluble and impermeable 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 due to the difficulties faced by the beverage industry.
Materials such as g fluorocarbon, nylon, ethylene vinyl alcohol (1_;VOH) and polyvinyl chloride (PVC) are now commonly used. EVOH and nylons are foundl 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 monorners that are carcinogenic and extraction of the plasticizes can occur over time.
Among the various known barners in use, fluorocarbon ranks among the best in regard to its inermess and impermeable properties. However, it is the most expensive.
Another recognized problem in tubing with a fluoroca~~bon or polypropylene inner layer is that these materials are extremely difficult to bond to tile other layers of the tubing.
1o 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 adsorbed 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 ei~ectively overcomes the inherent difficulties of stiffness, gas and flavour transmission, and flushability that face the beverage industry.
As follows, the present invention is considered to have sufficient novelty and ingenuity in overcoming many of the difficulties discussed above and offers a simple and economical 2o solution to vapour and gas transmission for a wide range of applications.

SLfwIMAItY OF THE INVENTION
It is therefore an object of the present invention to provide an e~cient 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 tubing for beverage dispensing which is comprised of an environmentally friendly inner layer, P.J.1, made up of copolyester with molecular formula (CmHg04) without any hazardous ingredients. This layer is bonded to the EVOH layer by a bonding layer P.J.2 which is a modified Polyethylene copolymer.
Applicants have found that by using carefully controlled conditions, an inner layer P.J.1 can be efficiently bonded via P.J.2 to the incompatible EVOH layer. The choice of P.J.1 and P.J.2 are unique to the process in that these layers have contributed towards the making of an impervious tube with all desirable attributes representing novelty and applicability to the beverage industry.
According to the invention, a novel five-layered tubing for beverages is provided. The beverage contact layer of about 0.1 mm is formed from a first thermoplastic material P.J.1 under a careful extruding temperature between 200-300°C, under the inert atmosphere of nitrogen or carbon dioxide or a mixture of both which have passed through a proprietary filter for achieving the non-brittle properly of the tubing. The P.J.1 layer is bonded to EVOH by P.J.2 in the temperature range 200 - 300°C while passing a stream of dry nitrogen through the tube, and then the EVOH is bonded to the outer Polyethylene layer (P.E.) by 5 P.J.3. Thus there are five layers in the developed process.
In the preparation of the test films, the preferred rate of reaching the said temperature was found to be 15°C per minute. A thin filin 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 150°C and at pressure of about 1000 psi. The outer layer may be either to linear low density polyethylene, ethylene vinyl acetate or any other variety of thermoplastic material suitably selected for the purposes of the outer layer and providing the desired flexibility. The absence of stiffness and brittleness, coupled with the inertness and other desired attributes such as cost, makes P.J.1 the perfect non-permeable material of choice and is what makes this invention so attractive.

BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present invention will be more apparent from the following description of a preferred embodiment as illustrated by way of examples in the accompanying drawings in which:
FIG. 1. is a sectional view of the five-layer Class I tubing for dispensing beverages in accordance with one embodiment of the invention.
FIG. 2. is a view of the three layer Class II tubing for dispensing beverages in accordance with the invention.
FIG. 3. is a schematic illustration of film making in accordance with another embodiment of the invention"
1o FIG. 4. is a schematic illustration of the experimental set-up used to perform the gas and water vapour permeability studies.
FIG S. Schematic illustration of experimental set-up used to perform flavour permeability studies.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the design, which is schematically illustrated in FIG. 2, a Class II tubing with three layers is shown for transporting a beverage through the tubing. Beverages are normally dispensed through several tubes in close proximity carrying different beverages and syrup to the dispenser. The beverages may include colas, alcohols, carbonated and non-carbonated drinks, and other liquid forms of drinks. The carbonated beverages are comprised of several ingredients including the syrup, and the water to which carbon dioxide has been added. The syrup has flavouring materials, which may be derived from natural fruit or synthetic materials. The carbon dioxide solubility is normally increased by applying pressure or by lowering the water temperature to near freezing.
1o The multilayer tube of the present invention contains at least one bonding layer, an outer layer and an inner barrier layer. The two types of tubing of this invention, having the same inner layer material but different bonding and other layers, are presented in Figures 1 and 2.
The tubing for Figure 1 is composed of five layers and that of Figure 2 is composed of only three layers.. The tubing of the present invention is preferably fabricated by co-extruding the given thermoplastic materials in a conventional co-extrusion process. The tubing may either be co-extruded to a suitable length or may be co-extruded continuously and cut to fit a particular application at a subsequent time. The outer diameter of the tubing can be varied as required. The thickness of the wall material of the tube can be varied as required.
However in many beverage applications the preferred thickness of inner layer, P.J.1, can be 0.1 mm to 0.5 mm. The multilayer tubing can be made with various layers by the method of l3 this invention; however, the present invention generally has a maximum of five layers inclusive of bonding layers. In the preferred embodiments, the tubing has five layers in the Class I tubing and has a maximum of three layers for the Class II tubing.
The P.J.1 layer of the present invention is common to both classes of tubings for use in beverage dispensing. This constitutes the inner layer, which is the only layer to be in contact with the beverage. It is non-reactive with the beverage environment and can withstand various stresses and strains caused by changes in flow velocities, fitting installation, and changes in temperature to which the tubings and beverages may become exposed to during the normal course of dispensing and filling operations.
As shown in Figure 1, the beverage flows through the inner layer of the tubing and its taste and odour are unaffected. The inner layer, P.:f-11, is impermeable, chemically inert, perfectly stable, and therefore fimctions as a protective layer for the beverage contained for dispensing.
Any contaminants from the middle and outer layer are unable to transmit the organic volatiles through this low cost but high performance barrier.
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 the commonly used barrier layers, which have been discussed before. According to the 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 0.05 2o mm or more and the outer layer about 1.0 mm or more. T'he integrity of the inner layer is ll4 sufficient to contain the carbonated drinks amder pressure and eliminate any blistering problems. Under the processing conditions of temperature and pressure, the inner layer does not suffer from cracks or brittleness. The processing and extrusion conditions do not require any significant modification to the capital equipment and operational raw material costs of the extrusion process. Therefore, switching ~to this inner layer provides an economically attractive and safe beverage dispenser tubing.
To convert the tube for application in high-pressure environments, yarn reinforcement can be used, as is known to the art. Additionally, the tubing of the present invention can be modified so as to add further protective outer layers. Such outer layers may be made of materials so as to provide it with structural and insulation capabilities.
It is recognized that the main embodiments of this invention, discussed in these detailed disclosures, can be further modified by those skilled in the art. The following non-limiting examples further illustrate the invention, and the testing carried out to confirm the performance properties.

EXAI~iPLE 1 The elemental analysis of the inner layer, middle layer and outer layer materials for the Class II tubing having three layers, were performed for material balance using a Carlo Erba instrument. The carbon and hydrogen analysis was performed by combusting a known weight of sample at 1000°C in the presence of 02. The resulting gases namely C02 and H20 5 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 satisfactory mass balance within acceptable experimental error. These to results indicate that the composition of the materials used contain carbon, hydrogen and oxygen only. Therefore an agreement between the theoretical and experimental values was found.

Elemental Composition of Class II Tube Composition by Weight Elements Inner Layer FoundMiddle Layer FoundOuter Layer (P.J.1 ) (P.J.4) Found (P.E. layer) 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 100.06 100.11 100.15 * Values in brackets are calculated expected values.

EXAI~iPLE 2 A thin filin polyester P.J.1, of formula (C,oH804)o, in the thickness range of about 0.1 mm to about 0.5 mm, was prepared in the laboratory as shown in Figure 3. In this method, the polyester P.J.1 in pellet form is uniformly spread over the bottom die and the top die is placed on it. The dielP.J.1/die set is protected from air by the flowing stream of nitrogen which has been pre-treated by passing through PJD, and purges the entire system of the 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 tlhe thermocouple has reached about 270°C the die set is taken out and pressed immediately to about 1000 psi or sufficient to the thickness to of the film required. The thickness of the film can be controlled by applied pressure. The die set is cooled in water and the film is removed for testing. Such processing conditions of temperature and inert atmosphere are 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, the contents were boiled in a beaker for an hour, cooled to room temperature and the water with the film in it was kept for 7 days. The water was them analyzed by Inductively Coupled Plasma for various metals. The anions were analyzed by a standard technique of Ion Chromatography.
The results are presented in Table 2. These results indicate that the filin P.J.1 made of Polyester material does not add any impurity, and that the water remains unaffected and 2o meets the drinking water criteria as shown ill Table 2.

TAaLE 2 Sample Water Parameter Tested Extract with MAC**
P.J.l (mg/L) Film cons;entrations (mgt) 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. 0.01 Mercury < 0.001 0.001 Manganese N.D. 0.05 Selenium N.D. 0.01 Uranium N.D. 0.10 Nitrite (as N) <I).1 1.0 Nitrate (as N) <I).1 10.0 N.D. = Not Detected Detection limit = 0.005 mg/L
Detection limit for Mercury (Hg) = 0.001 mg/L
** MAC = Maximum Acceptable Concentration as a Drinking Water Objective - Health Related EXAl~iPLE 3 In another experiment, a Class II tube was filled with high purity water that was kept in the tube for 15 days and then the water was analyzed by Inductively Coupled Plasma for various metals. The objective was to determine if any metallic contaminants were present in the tubing since contamination may have occurred by the use of catalysts during the polymeric materials manufacturing process. The results .are presented in Table 3. These results indicate that the tube does not add any metallic impurity and the water remains unaffected, thus meeting the Drinking Water Objectives.

Parameter TestedHigh Purity Water Water sample MAC**
(mg/L) from (mg/L) inside the tube (mg/L) Aluminum N.D. N.D. 0.10 Arsenic N.D. N.D. 0.025 Barium 0.001 ~ 0.001 1.0 Boron 4.010 0.012 5.0 Cadmium N.D. N.D. 0.005 Calcium 0.14 0.10 -Chromium N.D. N.D. 0.05 Cobalt N.D. N.D. -Copper N.D. N.D. 1.0 I
'~ Iron 0.003 0.003 0.30 '' Lead N.D. N.D. 0.01 Magnesium 0.01 0.02 -Manganese <0.005 <0.005 0.05 Mercury < 0.001 < 0.001 0.001 Nickel N.D. N.D. -Selenium ~ N.D. N.D. 0.01 Sodium 0.15 0.12 -Vanadium N.D. N.D. - I, Zinc <0.02 <0.02 5.0 N.D. = Not Detected Detection limit = 0.005 mg/L
Detection Limit for Mercury (Hg) = 0.001 mg/L
** MAC = Maximum Acceptable Concentration as a Drinking Water Objective - Health Related 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 the technique of GC/MS using a Hewlett Packard GC/MS with Tekmar Purge and Trap.
The results are presented in Table 4. These results clearly indicate that the film P.J-1 does not 5 impart any organic volatile impurities and that: the water remains unaffected, as in its original environmental state in which organics were not detected.

Parameters Results of WaterMaximum Drinking Sample A~ialysisWater Limit with Concentration P.J.1 fivn contact(mg/L) Concentrations (mgt) Benzene N.D. 0.005 Toluene N.D. 0.02 Xylene N.D. 0.3 0 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) EXA11~IPLE 5 In another experiment, high purity water was kept inside the new Class II
tubing at room temperature for 10 days. The contained water was then scanned for possible organics by the technique of GC/MS using a Hewlett Packard GC/MS fitted with a Tekmar Purge and Trap.
The results are presented in Table 5. These results further confirmed, that with P.J.1 as an inner layer, the tube does not impart any organic volatile impurities and that the water remains unaffected and remains in its original environmental state.
Table 5 Parameters Blank water Water sample Maximum Drinking (mg/L) from Water Limit Tube (mg/L) (mg.L) Benzene N.D. N.D. 0.005 Toluene N.D. N.D. 0.02 Xylene N.D. N.D. 0.30 I Ethyl Benzene N.D. N.D. 0.002 Volatile OrganicsN.D. N.D. 0.01 TrichloroethyleneN.D. N.D. 0.05 Trihalomethane N.D. N.D. 0.3 5 Other Organics N.D. N.D.

N.D. = Not Detected (<0.001 mg/L) EXAnZPLE 6 The inner layer film, P.J.1, was prepared by the method described above and was subjected to a permeability performance test. The apparatus shown in Figure 4, 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 transrnittance of vapours and gases from A
to B can occur only through the membrane. Septum 1 and Septum 2 are provided for the withdrawal of samples for analysis by a standard technique of gas chromatography.
In a typical water vapour transmittance determination experiment, the technique involved the passing of helium (or nitrogen) through a bubbler, which contained water to humidify the helium. By the opening and closing of valves l and 2, Side A of the cell was saturated with 1 o water vapour. Side B was kept dry by the flowing 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 of water from both 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, then oxygen and permeability experiments were repeated under a steady state condition. Carbon dioxide and oxygen were not detected on Side B of the cell. These results are presented in Table 6 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 or more thickness and under identical conditions.

Therefore the novel polyester as an inner layer is found to be an excellent barrier.
TA~3LE 6 Permeant Film Membrane Temp. ConcentrationConcentration of (barrier) (C) Permeant on of Permeant on of this Invention Side A of Side B of Cell Cell Water i Polyester 2:3-24 Saturated N.D.
~

(P.J.1 ) C02 Polyester 23-24 Saturated N.D.

(P.J.1) 02 Polyester 2'.3-24 Saturated N.D.

(P.J.1 ) N.D. = Not detected Polyester = Copolyester of forlr~ula (CloHg04)n In another embodiment of experiments, the v~rater in the bubbler (Figure 4) was replaced by alcohol, acetone and pentane and allowed to attain a steady state. The concentration of the permeant was measured by gas chromatography. The results of analysis clearly showed that the Polyester .J.1) membrane does not allov~r permeation of organic volatiles.
These results are presented in Table 7. P.J.1 is therefore the material of choice to prevent transmission of organics.

Permeant Film Membrane Temp. ConcentrationConcentration of of (barrier) (C) Permeant SidePermeant Side A B

ambient Ethyl AlcoholPolyester 23 -24 Steady State N.D.

(P.J.1) Saturation Acetone Polyester 23:-24 Steady State N.D.
I

(P.J.1) Saturation Pentane Polyester 23~-24 Steady State N.D.

(P.J. l ) Saturation ~ Pentane Polyethylene 23~-24 Steady State Detected Saturation N.D. = Not Detected Polyester = Copolyester of formula, (CioH80a)"
EXA11~PLE 8 In a preferred embodiment, permeability measurements were carried out with actual beverages using Cola, Root Beer, Beer and Scotch Whisky. The apparatus in Figure 4 was modified and Side A was saturated with each of the beverages and tested individually. In steady state conditions the permeability results are reported in Table 8. In a separate study, the known barrier materials EVOH (ethylene vinyl alcohol), Nylon-6, Nylon-11, amorphous Nylon, PVDF, a fluorocarbon, polyethylene and copolyester, were tested for permeation and solubility using methyl salicylate as the permeant. Among all the materials tested, copolyester ranked the best having the lowest permeability and solubility rates. Additionally, humidity was found to greatly increase the permeability of EVOH and Nylon. The low cost 1 o of the P.J.1 material coupled with its superior transmission properties makes P.J.1 the most logical choice as a barrier material found by the virtue of this invention.

The Results of Study Barrier Properties of P.J.1 Permeant Film Temp ConcentrationConcentrationPermeation Membrane (C) of Permeantof Permeant ambient on Side on Side B
A

Cola ~ Polyester 23-23 Saturated N.D. None ~

(P.J.1 ) Cola 2 Polyester 23-24 Saturated N.D. None (P.J. l ) Root Beer Polyester 23-24 Saturated N.D. None (P.J. l ) Beer Polyester 23-24 Saturated N.D. None (P.J.1 ) Scotch Polyester 23-24 Saturated N.D. None Whisky (P.J.1 ) N.D. = Not Detected PolyestE;r = Copolyester of formula, (CloHg04)"

Zs The barrier properties of the Class II tubing with P.J.1 as an inner layer were tested for flavour transmission in a specially designed experimental set-up shown in Figure 5. The schematic diagram is self explanatory. It consists of the plastic tube to be tested, and an outer glass jacket filled with high purity water in contact with the outer layer of the tube. The Class II tube was filled with Root Beer and was allowed to stand for about 15 days at room temperature so that the tube walls became saturated with Root Beer. Root Beer contains a low concentration (about 150 ppm) of methyl salicylate as flavour. The detection of~methyl salicylate in the permeant was used for the measurement of permeation.
The components of Root Beer permeating through the wall of the tubing were allowed to l0 collect in the shell tube containing water. The; sample of water was withdrawn and analyzed for presence of the permeant by the technique of GC/MS using Purge and Trap. A
similar set-up was fabricated and used for the permeation study of other plastic samples. The results are presented in Table 9.

Study of Flavour Permeability of loot Beer Through Various Tubes Sample Saturation PeriodMethyl SalicylatePermeation Class II Tube 15 days Not Detected No Polyethylene 15 days Detected Yes I
(> 10 ppm) Detection Limit = < 1 ppb For application in beverage dispensing, as i;~ the tubing of this invention, the tube must preferably be washable or flushable with water. The polyester discs were soaked in two major Colas and Beer for 24 hours at room temperature. The treated discs were successively washed with distilled water. The wash solutions were collected and analyzed by GC/MS.
5 ml samples of each wash solution were intlnduced to the Tekmar Purge and Trap system and analyzed by a Hewlett-Packard GC/MS. The results of analysis are presented in Table 10. These results indicate that the film surface is flushable, implying that the surface adsorption is insignificant.

Results of Flushability of P.J.1 Surface Detection in Wash Cola Detected Detected N.D. N.D. N.D.

Cola Detected Detected N.D. N.D. N.D.
2 ~

Beer Detected Detected N.D. N.D. N.D.

N.D. = Not Detected Commonly used beverage dispensing tubing. available on the market, was tested for the release of contaminating gases and vapours upon purging or creating a pressure differential by evacuation. The P.J.1 disc was tested by evacuation only.
Each experiment on the commercially-available beverage tubing was comprised of purging a certain length of tubing by passing a stream of helium through the inner layer of the tube and analyzing the gases and vapours released by using a Hewlett Packard GC/MS.
The results are presented in Table 11. As can be seen from the results of Table 11, the polyester disc P.J.1 does not release any such contaminant, and is therefore environmentally safe.

Source Test Contaminants of Method Found Tubing Commercial tubing currentlyHelium C7 - Coo used on the market Purge & Trap Hydrocarbons for Beverage Dispensing Commercial tubing currentlyEvacuation C7 - Cio used on the market Hydrocarbons for Beverage Dispensing Copolyester (P.J.1 Evacuation None disc) EXAN;IPLE 12 Certain surfaces may contribute to microbial growth when in contact with beverages. A
microbial growth test was carried out using the Class II tubing. The study showed that the tube does not contribute to microbial growth 'when exposed to 5% sugar solution at 23°C for a period of seven days.

Claims (30)

1. A novel and environmentally friendly layered tubing for the carrying and dispensing of beverages. The tubing is referred to as Class I and Class II in accordance with the materials used for construction of the tubes. The inner layer material is the same for both Class I and Class II tubes.
The Class I tubing is composed of a flexible outer layer of a given thickness, and an inner layer of copolyester of a general formula (C10H8O4)n including its modified variations. In one construction, the inner Polyester (PET) layer is bonded to an Ethylene Vinyl Alcohol layer using a bonding Polyethylene copolymer with modified polyolefin. The outer surface of the EVOH layer is bonded to the inner surface of the outer layer, Polyethylene. In this construction, the thermoplastic materials of the inner, intermediate, outer, and bonding layers are essentially extrudable thermoplastics capable of permanent adhesion with their respective layers as described in the embodiment of the 5 layer construction of the Class I tube.

2. The layered tubing of Class II is composed of a flexible outer layer of a given thickness and a copolyester (PET) firmer layer of a general formula (C10H8O4)n and its modified variations. The two layers are bonded by a middle layer of general formula (C8H16O)n or modified variations. In the Class II tube construction, as described in the detailed description of the embodiment, there are three layers inclusive of the bonding layer. The bonding layer in the middle is capable of permanent adhesion to the inner and outer layers.
The two classes of environmentally friendly tubing described in this invention offer an alternative to the sources of raw materials currently in use and are complementary to each other. The beverage contact layer has been chosen from a low cost thermoplastic material which is a copolyester of general formula (C10H8O4)n.
This material is to be used as an inner convict layer in beverage tubing of both Class I and Class II.
The outer plastic layer is a low cost polyethylene with formula (C2H4)n and is non-compatible with the inner contact layer. Therefore a bonding layer is required.

3. The inner layer composed of a copolyester is the gas barrier layer which is inert, odourless, insoluble in water, alcohols, beverages, syrups and alike.

4. The inner layer in general, has 10 Carbon, 8 Hydrogen and 4 Oxygen atoms with the general formula (C10H8O4)n, but modifications and variations can be made.

5. The tubing described in Claim 1 and Claim 2 wherein the said inner layer can be a modified copolyester with variation in composition and substituent groups.

6. The tubing described in Claim 2 of Class II wherein the middle bonding layer can be co-extruded with other materials having adhesive properties. The outer layer can be of low density or high density polyethylene, polypropylene, ethylene vinyl acetate, polyvinyl chloride, or any other form of thermoplastic suitable for this purpose.

7. The tubing described in Claim 2 wherein the said contact layer is about 0.1 mm thickness or more, with the middle layer about 0.05 mm in thickness or more and the outer layer is about 1.0 mm or more.

8. The tubing described in Claim 1 wherein the said contact layer is about 0.1 mm thickness or more and the outer layer is about 1.0 mm or more. The thickness of the intermediate and bonding layers can vary.

9. The optimum formation of the inner layer of polyester, free from stiffness, odour and colour changes for Class I and Class IT tubing, can preferably be attained by passing nitrogen or another inert gas through a pre-treatment filter which consists of silica gel and activated carbon that can be regenerated as necessary. For the purposes of this invention a trade name "P.J.D." is given to the pre-treatment filter.

10. The inner layer described in Claim 1 and Claim 2 wherein the bonding layer can be chosen from other materials with adhesive properties and a thermoplastic elastomer.

11. The tubing described in Claim 1 and Claim 2 wherein the said thermoplastic elastomer is polypropylene-based.

12. The tubing described in Claim 2 of Class II wherein the said tubing may comprise of inner, middle and outer layers of the same copolyester.

13. The tubing described in Claim 1 of Class I wherein the said tubing may comprise of inner, intermediate and outer layer of the same copolyester.

14. The tubing described in Claim 1 and Claim 2 wherein the said beverage contact layer and other layers are each approximately the same thickness or of different thickness.

15. The Class II tubing described in claim 2 wherein the thickness of inner contact layer can vary.

16. The Class I tubing described in Claim 1 wherein the thickness of inner contact layer can vary.

17. The Class II tubing described in Claim 7 wherein the said contact layer can vary from 0.001 inches to 0.003 inches and the said outer layer to about 0.024 inches in thickness.

18. The tubing described in Claim 8 wherein the thickness of inner contact layer can vary from 0.001 inches to 0.003 inches, and the said outer layer to about 0.024 inches in thickness and the intermediate and banding layers can appropriately vary.

19. The bonding layers of the Class I tube referred as P.J.2 and P.J.3 in the detailed description of the embodiments are comprised of P.J.2 is Polyethylene copolymer with modified Polyolefin having about (experimental) % C = 79.2, % H = 13.6%, %O = 7.6 with traces of N. Other modified forms with varying % compositions can also be used.
P.J.3 is modified Polyolefin having; about (experimental) %C = 84.7, %H = 15.3 and %O = 1.2. Other modified forms with varying % compositions can also be used.

20. The bonding layer (middle layer) of the Class II tube referred as P.J.4 in the detailed description of the embodiment is comprised of P.J.4 having elemental composition: %C = 75.0, %H = 12.5, %O = 12.5. Other modifications with suitable variations of functional group can also be used.

21. A Class II tubing for beverages having multiple layers, with the said tubing comprised of:

a beverage contact layer formed from a copolyester which does not impart taste or flavour, and resists odour transmission to the beverage and from the beverage.

22. A Class II tubing for beverages having multiple layers with the said tubing comprised of:
a beverage contact layer formed from a copolyester which does not impart taste or flavour and resists odour transmission to the beverage and from the beverage.

23. Under the conditions of temperature and heating rate, the chosen inner layer of the Class II tubing does not develop cracks when affixed to a coupling and subjected to mechanical and chemical stress.

24. Under the conditions of temperature and heating rate, the chosen inner layer of the Class I tubing does not develop cracks when affixed to a coupling and subjected to mechanical and chemical stress.

25. The films and sheets of various thickness can be formed from the materials used for making P.J.1 which can be of great importance to the food packaging industry.

26. The films and sheets provide a thermally stable, inert and impermeable material which may allow freezer-to-oven service in the food market.

27. Various sizes of films and discs can he made which will find applications as inert liners or caps for environmental sampling bottles replacing expensive fluorocarbon liners.

28. The film liners of P.J.1, being less expensive than fluorocarbon liners, and meeting EPA criteria for drinking water contact material, may find various applications in drug packaging.

29. The material P.J.1 can replace applications of polypropylene and EVOH for certain retort applications.

30. The P.J.1 material does not contain Chlorine atoms in its molecule and being impermeable, can lead to various applications where toxicological concerns are associated with thermoset materials and chlorine-bearing materials.