Note: Descriptions are shown in the official language in which they were submitted.
CA 02263603 1999-02-22
W 098/10927 PCT/CA97/00647
POLYMERIC MULTILAYER HEAT EXCHANGERS CONTAINrNG A BARRIER
LAYER
FIELD OF TH~ INVENTION
s This invention concerns a heat e~c~h:~nger wherein the material which comprises
the heat exchange surface structure cont~inc at least one polymeric barrier layer and at
least one polymeric thermoplastic layer.
TECHNICAL BACKGROUND
Heat exçh~ngers are common pieces of equipment, used in many applications,
0 such as chemical processes, in automotive uses, household uses, and others. Heat
exch~ngers are most commonly used to transfer heat between two fluids such as two
liquids, a liquid and a gas, or between two gases. Traditionally, the materials used for
the heat exchange surfaces are metals, which usually have relatively high thermal
conductivities and good strength. However metals have certain drawbacks, such as high
forming and assembly costs~ relatively high densities and therefore high weights, and
sometlmes poor corroslon reslstance.
To overcome some of these disadv~nt~es, heat exchangers using plastics have
been developed. For in~t~n~e, in highly corrosive environments heat exchangers using
polytetrafluoroethylene (or perfluorinated tetrafluoroethylene copolymers) have been
20 used. However plastics have some inherent disadvantages, such as poorer heat transfer
coefficients, in some cases relatively poor chemical stability, and permeability to the
gas(es) or li~uid(s) which contact the heat exchange surfaces. However, they often offer
the advantages of lighter weight and easier fabrication than metals. The.crore, improved
plastic heat e~r~h~rlgers are sought.
J~r~n~se Patent Application 03/007891 describes a heat exell~nger tube made
from a liquid crystalline polymer and a filler having high heat conductivity. No mention
is made of a tube having multiple layers of polymers.
French Patent Application 2,566,107 describes heat ~ch~nger panels made from
polymers such as polyethylene. No mention is made of layered plastics or barrier layers.
U.S. Patents 4,923,004, 4,955,435,5,275,235 and 5,316,078 describe heat
ngers which employ various polyamides for the heat e~ch~n~e surface m~teri~l~
Barrier layers are not mentioned in these patents.
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D. A. Reay, Heat Recovery Systems & CHP, vol. 9, p. 209-16 ( 1989), and I. H.
Gross, Procee~ings of Antec '93, p. 964-968 (1993) describe the use of polymers in heat
exchangers. No mention is made of using layered polymer structures, nor of using L~Ps.
SUMMARY OF T~E INVENTION
This invention concerns, a multilayer heat ~xch~nger col.tS~ ,g a heat exrh~nge
surface m~teri~l, said HESM comprising a polymeric barrier layer and a layer of a second
polymer.
This invention also concerns a heat e~ch~nger panel wherein a heat çxch~n~e
0 surface material comprises a layer of a polymeric barrier layer and a layer of a second
polymer.
By a heat exchange surface material (HESM) is meant a material which is used as
part o~ a heat exçh~n~er or a component thereof, and which is the material through which
the ma}or portion of the heat that is exchanged between the two fluids (gas or liquid) is
meant to flow. It also performs the function of keeping the two fluids between which
heat is being exchanged apart.
BRIEF DESCRIPTION OF THE DRAWINGS
Both figures 1 and 2 depict the al~palaL~Is that used to produce the film as
described in Example 6.
Figure I is a sch~m~tic drawing from the side, of an app~lus for carrying out the
multilayer film forming process described herein. An extruder, 1, supplies molten first
therrnoplastic to slit die 2 from which issues a molten multilayer thermoplastic film 3. A
second extruder, 34, supplies molten second thermoplastic to slit die 2. A third extruder,
35, supplies molten third therrnoplastic to slit die 2. The molten 3-layer film 3 falls
2s vertically until it contacts approximately simlllt:mloously embossed surfaces 7 and 8 of
rollers 5 and 6, respectively. Rolling bank 4 of thermoplastic is also present. Rollers 5
and 6 are driven in rotation in the directions shown. Multilayer film 9 exits the gap from
bclweeJI rollers 5 and 6, goes between (optional) cooling rollers 9 and 10, and is wound
up on windup roll 11.
Figure 2 shows the same rollers 5 and 6 and rolling bank 4 from the top, together
with one method of osçill~tin~ the rollers 5 and 6 parallel to the axis (center line) of each
of these rollers. Lever 9 is connected to a fixed point by pin 10, and to arms 13 and 14
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by pins 19 and 20 respectively. The arrns 13 and 14 are connPcted to rollers ~ and 6
respectively, through thrust bearings 15 and 16 Ic~ec~ ely, allowing rollers S and 6 to
rotate while being oscill~tef1 Lever 9 contains slot 16 into which cam 17 is fitted.
Motor 18 rotates cam 17 thereby causing lever 9 to oscillate ap~uloxilllately
s perpendicularly to the rotational axis of rollers ~ and 6. This causes ~ and 6 to oscillate
in directions opposite to each other and parallel to their rotational axis.
In other words in this appa dLus the molten multilayer film formed in the slit die 2
is passed through rollers which oscillate along the axis of rotation of the rollers, thereby
pal~hlg a transverse (to the direction of movement of the film) .~hç~ling action to the
0 molten polymer of the multilayer film.
DETAILS OF THE INVENTION
Heat exchangers described herein function to exchange heat (energy) between
two fluids. These fluids may be gas(es) and/or liquid(s).
One of the materials which is part of the HESM is a polymer layer (PL). By a
polymer layer is mean a layer that is made of a natural or synthetic polymer, preferably
an organic polymer. It is also preferred that the PL is a thermoplastic. Any polymer may
be used so long as it meets certain requirements. It must of course withstand the
tempe~dLules to which the HESM is exposed, and should throughout that tel~ aLu
range provide sufficient strength (together with the barrier layer) to the HESM to
20 reasonably m~int~in its shape and contain the fluids in the heat exrh~nger, as needed,
unless the HESM is deliberately ~lesi~n~d to be flexible. If it is exposed to one or more
of the fluids in the heat exch~nger (or any other adventitious materials that may contact
it) it preferably should be reasonably chPmic~lly stable to those fluids so as to m~int~in
its integrity.
2s Although various types of heat eYrh~n~ers made simply of single layers of
polymers have been described, they sometimes have serious drawbacks when they are
the only m~t~ri~l~ in HESMs. Somçtimçs the polymer of the HESM may not be
chemically stable to one or more of the fluids in the heat çxrh~n~er, for in~t~nce~ many
polyesters hydrolyze or otherwise degrade in the presence of water, water-alcohol, or
30 water-glycol l~ es, especi~lly at higher than ambient tenlpelalules. Many polymers
are relatively permeable to many liquids and/or gases, and therefore allow losses and/or
migration of these materials in or from the heat ~Yrh~nger. Some polymers may be
~ CA 02263603 1999-02-22
swollen by one or more of the fluids used in the heat exchanger thereby ch~nging their
dimensions and/or physical properties. All of the above are of course problems in
polymeric heat e~cchangers.
It has been found that a polymeric barrier layer (PBL) used in the HESM often
5 alleviates or elimin~tes one or more of the above mentioned problems. By a PBL is
meant a layer whose polymer has a relatively low permeability to at least one of the
fluids that are e~cch~ngina the heat energy. If a gas phase/liquid phase heat exchanger is
being used, the perrneabilities refer to the liquid phase.
The polymer of a PBL should have a permeabili~y to a liquid or a gas which is
-- lo l/lO (O. l O) or less, preferably about l/l 00 (O.OlO) or less~ than the permeabilit~ of the
most permeable polymer layer in the multilayer structure. Alternatively the PBL should
have a permeability to liquids of about 3 l g-mil/m-/day (0.79 g-mmlm~/day) or less~
preferably about 3. l g-millm~/day (0.079 g-mrn/m-/day) or less, or a permeability to
gases (for a gas/gas heat exchanger) of about l 00 ml-mil/m~/day (2.5 ml-mm/m-/day) or
less, preferably lO ml-mil/m-/dav (0.~5 ml-mm/m~lday) or less. Permeability
measurements on liquids to obtain these values should be at 38~C, while measurements
on gases should be at 2~~C.
If the PBL is placed between a fluid and any particular PL in the HES~I it oftenprotects that PL from chemical degradation by the fluid, and/or also often protects the PL
~o from being swollen by that fluid. For instance, in automotive heat exchangers which
help cool the engine, the commonly used internal coolant is a mixture of a glycol and
water, and the e~cternal coolant is air. With many PLs diffusion of water and/or glycol is
so rapid that frequent replenishment of the water/glycol mixture is needed. If a PBL (to
the water/glycol mixture) is included, the diffusion is greatly decreased.
In order to obtain rapid heat transfer through the HESM, thickness through the
material between the heat transfer fluids should be as small as possible. This would be
true with any material used for an HESM, but is especially important with plastics since
their heat transfer coefficients are usually relatively low when compared to metals. Since
the PBL is often the more expensive of the polymers present in the HESM, it is usually
economically preferable to limit its use. Therefore, in most constructions it is preferred
~EN~E~ S~
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that the PBL is present in relatively thin layer~s) and that layer(s) of the PL be relatively
thick so as to carry much of the structural load of the HESM (i.e., pressure of the fluid(s),
;ll structural shape and dim~ lns~ etc.).
The HESM is made up of one or more PBL(s)and one or more PLs. If more than
PBL andtor PL is present, more than one type of PBL and/or PL, respectively, can be
used. In addition other layers may be present. For example, so called tie layers (TL),
also called adhesive layers, may be used to increase the adhesion beLween various PBLs
and PLs. or between PLs or between PBLs. The number and p~ eln.ont of the various
layers in the HESM will vary depending on the particular polymers chosen, the fluids
o used in or by the heat exch~nger, telllp~lalule requirements, enVirnnmpnt~l needs, etc.
Most commonly, tie layers and PBL(s) will be relatively thin coll.paled to the
PI,(s~. Typical constructions are given below, wherein Fluids 1 and 2 represent the fluids
involved in the heat transfer:
(a) Fluid I /PBL/PL/Fluid 2
(b) Fluid 11PL-I/PBL/PL-2/Fluid 2
(c) Fluid l/PBL-11PL/PBL-2/Fluid 2
(d) Fluid 1/PL-l/PBL-1/PL-2/PBL-2/Fluid 2
(e) Fluid l/PL-1/PL-2/PBL/Fluid 2
(f) Fluid 1/PBL-I/PL-1/PL-2/PBL-2/Fluid 2
20 In all of the above constructions, tie layers may be present between all, some or none of
the various polymer layers.
Some of the above constructions may be particularly useful in certain situations.
If Fluid l but not Fluid 2 chemically ~tt~ckecl the PL, construction (a) may be
particularly useful, but (c) and (f) may also be lltili7PIl If both Fluids 1 and 2 ~tt~r~d
25 the PL present construction (c) or (f~ may be particularly useful. If one wanted to
minimi7~ diffusion of one fluid to another, a construction having two PBL layers, such as
(c), (d) or (f) could be chosen. If a special surface is required to reduce abrasive damage
- on the Fluid 1 side, but great stiffnP~s is also required from the PL, a construction such as
(e) could be chosen wherein PL- 1 and PL-2 have the requisite properties. These and
30 other combinations of layers having the correct properties for various applications will be
ap~ ent to the artisan.
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Polymers useful as PBLs will depend on what the fluids that are being heat
e~.h~n~ed are. Perrneabilities of various polymers are known or can be measured by
known methods, see for instance ASTM E 96-95, ASTM F 1249-90 and ASTM D3985-
95. These methods measure gas or vapor permeabilities, but may be readily modified to
s measure the permeability of liquids, by using liquids in the measurement and having
them contact the polymer whose permeability is being measured. When testing the
permeability of a potential barrier polymer, it is preferred that test be carried out on a
single layer of the barrier polymer itself. For a list of polymer permeabilities see S.
Pauly in J. Brandrup, et al., Ed., Polymer Handbook, 3rd Edition, John Wiley & Sons,
o New York, 1989, p. VI-435 to VI-449. If a polymer acts as a PBL in one particular heat
exchanger, it may be only be a PL in another heat exchanger due to differing liquids in
the two heat exchangers.
If one of the heat exchange fluids is a gas and the other is a liquid (during actual
heat exchanger operation) it is preferred that the barrier layer be relatively impermeable
to the liquid. If both heat exchange fluids are liquids the barrier layer must be relatively
impermeable to at least one fluid liquid, but is preferably relatively impermeable to both
liquids. The same is true of a gaslgas heat ~xrh~nger. It is also preferred that the
permeability of the barrier layer be measured under telllpel.lLLIle conditions under which
the heat exchanger typically operates.
One preferred heat exchanger herein is an automotive or other heat ~xçh~n~er in
which one fluid is water a water/alcohol mixture, or a water/glycol (such as ethylene
glycol or 1,2-propylene glycol) mixture, and the other fluid is a gas, most commonly air.
Here it is p~cfelled that the barrier layer have a low permeability to the liquid fluid, the
water, water/alcohol, or water/glycol mixture.
Polymers which may be useful in PBLs for liquids include various polyolefins
such as polyethylene, polypropylene, ethylene/carbon monoxide copolymers and various
polycycloolefins, fluoropolymers such as poly(tetrafluoroethylene), polyesters such as
poly(ethylene terephth~l~te), poly(butylene terephth~l~t~), poly(ethylene 2,6-napthoate),
other polymers such as poly(vinyl chloride), poly(vinylidene chloride), and
30 polyacrylonitrile. For use in PBLs for gases polymers such as fluoropolymers such as
poly(tetrafluoroethylene), polyesters such as poly(ethylene terephth~l~te), poly(butylene
terephth~l~t~), poly(ethylene 2,6-napthoate), polyamides such as nylon-6,6, nylon-6, and
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high te.l-pcldlule nylons; and other polymers such as poly(vinyl chloride),
poly(vinylidene chloride), polyacrylonitrile, copolymers of ethylene and vinyl alcohol,
and poly(vinyl alcohol).
One preferred class of polymers for PBLs for both gases and liquids are li~uid
crystalline polymers (LCP). By an LCP is meant a polymer that is anisotropic when
tested in the TOT Test described in U.S. Patent 4,118,372. These polymers tend to have
very good barrier properties and are inert to many materials which are used as heat
ex~h~n~e fluids.
Useful LCPs include those described in U.S. Patents 3,991,013, 3,991,014
o 4,011,199, 4,048,148, 4,075,262, 4,083,829, 4,118,372, 4,122,070, 4,130,545, 4,153,779,
4,159,365, 4,161,470, 4,169,933, 4,184,996, 4,189,549, 4,219,461, 4,232,143, 4,232,144,
4,245,082, 4,256,624, 4,269,965, 4,272,625, 4,370,466, 4,383,105, 4,447,592, 4,522.974,
4,617,369, 4,664,972, 4,684,712, 4,727,129, 4,727,~31, 4,728,7~4, 4,749,769, 4,762,907,
4,778,927, 4,816,555, 4,849,499, 4,851,496, 4,851,497, 4,857,626, 4,864,013, 4,868,278,
4,882,410, 4,923,947, 4,999,416,5,015,721, 5,015,722, S,025,082, 5,086,158, 5,102,935,
5,110,896, and 5,143,956, and European Patent Application 356,226. Useful
thermotropic LCPs include polyesters, poly(ester-amides), poly(ester-imides), and
polyazomethines. Especially useful are LCPs that are polyesters or poly(ester-amides).
It is also ~lef~l-cd in these polyesters or poly(ester-amides) that at least about 50 percent,
20 more preferably at least about 75 percent, of the bonds to ester or amide groups, i.e., the
free bonds of -C(O)O- and -C(O)NR~- wherein R' is hydrogen or hydrocarbyl, be tocarbon atoms which are part of aromatic rings.
Included within the rlçfinition herein of a PBL is a blend of 2 or more polymershaving the required pçrm~bility.
Useful thermoplastic polymers for PLs (or PBLs in the proper circl~rn~t:ln~e~) are
those that have the requisite properties as described above, and include: polyolefins such
as polyethylene and polypropylene; polyesters such as poly(ethylene terephth~l~t~,
poly(butylene terephth~l~te), poly(ethylene 2,6-napthalate), and a polyester from 2,2-
bis(4-hydroxyphenyl)propane and a combination of isophthalic and ~e. plllhalic acids;
30 styrenics such as polystyrene and copolymers of styrene with (meth)acrylic esters;
acrylonitrile-but~lien~-styrene thermoplastics; (meth)acrylic polymers in-.hl-ling homo-
and copolymers of the parent acids, and/or their esters and/or arnides; polyacetals such as
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polymethylene oxide; fully and partially fluoropolymers such as polytetrafluoroethylene,
polychlorollinuoroethylene, poly(tetrafluoroethylene/hexafluoroprol)ylene) copolymers,
poly[tetrafluoroethylene/perfluoro(propyl vinyl ether)] copolymers, poly(vinyl fluoride),
poly(vinylidene fluoride), and poly(vinyl fluoride/ethylene) copolymers; ionomers such
as an ionomer of an ethylene-acrylic acid copolymer, polycarbonates; poly(amide-imides); poly(ester-carbonates); poly(imide-ethers); polym~lhyl~ue~ e; linear
polyolefins such as polypropylene; poly(ethPrketonek~tone); polyimides; poly(phenylene
sulfide); polymers of cyclic olefins; poly(vinylidene chloride); polysulfones; poly(ether-
sulfones); and polyamides such as nylon-6,6 nylon-6, nylon-6,12, nylon-6,12, nylon 4,6,
o and the polyamides from tel~hl}-alic acid and 1,6-hex~ne~ minP andlor 2-methyl-1,5-
pent~nP~ mine Polyamides are preferred PLs and preferred amides are nylon-6,6,
nylon-6, and a copolymer of terephth~lic acid with 1,6-hex~n~ mine and 2-methyl-1,5-
pent~nP~ min~ wherein 1,6-hex~ne~ minP is about 30 to about 70 mole percent of the
total tli~mine used to prepare the polymer. Especially preferred polyarnides are nylon-
6,6, nylon-6 and a copolymer of terephthalic acid with 1 ,6-h~n~ mine and 2-methyl-
1,5-pent~n~ minP wherein 1,6-hPY~ne~i~minP is about 50 mole percent ofthe total
diamine used to prepare the polymer. Included within the definition of the polymer for a
PL herein are blends of 2 or more polymers, for instance a polymer tongh~n~-l with a
rubber and optionally other ingredients.
Useful th~rrnosetting polymers for PLs (or PBLs in the proper circumstances) arethose that have the requisite properties as described above, and include epoxies,
thermoset polyesters, and phenolics. These polymers will be forrned into their final
shapes before being cro~slin~Pfl as is normal with thprmosetting polymers.
The polymers may contain other materials conventionally found in polymers,
2s such as fillers, reinforcing agents, antioxidants, antio70n~ntc, dyes, pigment~, etc. An
e~peci~lly useful material is a filler with high heat conductivity, which may increase the
efficiency of the heat e~c~h~n~er.
The composition of a tie layer will depend on which two polymers are on either
side of it. For in~t~nce the tie layer may be the polymer of a PL functionalized or grafted
30 to provide adhesion between the PL and PBL layers, or may be a blend of one or more
polymers of the PL and one or more of the polymers of the PRL(s).
CA 02263603 1999-02-22
W O98/10927 PCT/CA97/00647
Typical thi~n~c~es for PL layers will range from about 0.025 to about 0.25 mm.
Typical thickn~es for PBL layers will be about 0.01 to about 0.1 mrn. Tie }ayers will
usually be as thin as possible, consistent with their providing adhesion between polymer
layers. This is usually about 0.01 to about 0.1 mm. The total thickness ofthe structure is
s preferably less than about 0.7 mm, more preferably about 0.12 to about 0.5 mm, and
especially preferably about 0.15 mm to about 0.4 mm.
Heat exch~ngers of many different configurations are, made and used, see for
in~t~n-~e R. K. Shah, et al., in W. Gerhartz, et al., Ed., Ullmann's Encyclopedia of
Industrial Chemistry, 5th Ed., Vol. B-3, VCH Verlagsgesellschaft mbH, Weinheim,
0 1988, p. 2-l to 2-108. As can be seen from this article, and is well known in the art,
probably the two most common heat exchange "elements" are the tube and the plate. In
a tube type heat exchanger one of the fluids flow through a usually circular cross
sectioned tube, while the other fluid flows on the exterior of the tube. Usually many
small tubes are employed to create a large heat exch~nge surface. Som~tim~s the tubes
may be finned for more efficient heat transfer. In a plate element, small passageways,
akin to small tubes, are fabricated within plate of the heat exchange material. One of the
fluids flows on the inside of the passageways while the other fluid flows over the exterior
surface of the plates. The passageways are usually small to increase surface area, and
multiple plates are often used. All of the ~liscllC~ion about heat exchange surface
20 materials also applies to heat exchange panels.
For tube type heat exchangers cont~ining LCPs, the multilayer material describedherein can be made by multilayer coextrusion of a thermoplastic tube, see for in~t~n~e
U.S. Patent ~,288,529. However, LCPs when so extruded tend to be weak in the
transverse direction (perpl~nfiic~ r to the long axis of the tube). Such problems can be
2s solved by using a cou"l~,-lul~ling die for the LCP portion of the extruded tube, as
described in U.S. Patents 4,963,428 and 4,966,807, and G.W. Farell, et al., Journal of
Polymer F.ngin~ering, vol. 6, p. 263-289 ~1986). The tubes can be assembled into a full
heat exchanger by inserting them into tanks with proper size holes and sealing the holes
with a filler such as epoxy resin, or by heat sealing (e.g., melt welding).
Heat exchanger plates of the layered material described herein may be made by
relatively standard methods. They may be directly coextruded, complete with passages
in them. A flat sheet or film may be coextruded, therrnoformed into the correct shape
~ CA 02263603 1999-02-22
' " '
and joined adhesively or by heat into the plate. Such coextrusions are known processes,
see for instance H. Mar, et al., Ed., Encyclopedia of Polymer Science and Engineering,
2nd'Ed., Vol. 6, John Wiley & Sons, New York, 1986, p. 608-613, ibid., Vol. 7, 1987, p.
106- 127, all of which is hereby included by reference. Individual films or sheets of the
PL(s) and PBL(s) may be l~min~ted together, then formed into a heat e~cchanger plate.
For fabrication of a plastic heat e~cchanger made with plates see U.S. Patent 4,955,~35.
The beat e~changers described herein are useful for ~utomotive and other vehicleuses, in aircraft, as comfort heat e~changers, and various ventii~ting, heating'~nd air
conditioning applications. They are particularly useful as liquid-gas heat e,Ychangers
o used to cool automotive gasoline or diesel engines. In that case the liquid is usually
water, water and a glycol, or water and an alcohol.
EXAMPLE I
Small diameter tubing (~0.37 cm diameter and 250-310 ,um wall thickness) was
made with multilayer construction, nylon 66/LCP/nylon 66, using three e~truders nd a
s die to separately feed the different materials as separate layers. The LCP was a polyester
of the composition ~,4'-biphenolfhydroquinonelterephthalic acid/2,6-naphthalene
dicarboxylic acid/4-hydro~ybenzoic acid/6-hydroxy-2-naphthoic acid (mole ratio
50/50/70130/270/50). The LCP layer was about 51 ~m thick. The tubing was sealed at
one end, then filled with a 1: 1 (vol.) miYture of commercial automotive antifreeze and
~o water, subsequently sealed at the other end and then placed in an oven maintained at
100~C. The loss of the fluid with respect to time, was obtained by weighing. The loss
was found to be: 7.7 g/m2 (0.5 gm/100 in') tubing surface area/day.
EXAMPLE 2
A heat exchanger was constructed from coe~ctruded tubing (OD 0.366 cm~ ID
0.328 cm) of configuration (inside of tube to outside) 64 !lm HTN nylon/ 51 llm LCP (as
in E.Yamplel)176 ,um HTN nylon and active surface area of 1.959 m~. The HTN was a
blend of a polyamide which is a polymer of 1,6-he~ane~i~mine and 2-methyl- 1.5-
pentane~i~mine (1:1 mole ratio) and terephthalic acid, with a synthetic rubber (~'ordel(~)
3681, and EPDM-type rubber, available from E. I. DuPont de Nemours & Co
Wilmington, DE, 19898) and a functionalized synthetic rubber (which is a maleic
anhydride functionalized EPDM) in an 85/15/5 weight ratio, respectively.
AMENOED S~E~
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Hot water (81 ~C) was circulated through the exchanger while ambient air was
passed across the surface of the tubes. Operation over a total of 24 days resulted in a loss
of 201 gm water, equivalent to a water loss rate of 4.3 gmlm2124 h.
~ EXAMPLE 3
A film of the following composition was produced by the blown film coextrusion
method:
layer 1 nylon 6/Sclair~) 1 lKl~/Fusabond~
D226bla functionalized synthetic rubbef
(72.5113.616.816.8 weight percent) 0.05 mm
layer 2 XB603 (function~1i7Pd EMA) 0.01 mm
layer 3 LCP 0.01 mm
layer 4 XB603 0.01 mrn
layer 5 LCP 0.01 rnm
layer 6 XB603 0.01 mm
layer 7 Same as Layer 1 0.05 mrn
aLLDPE available from Nova Chemicals, Calgary, Alberta, Canada
hA maleic anhydride grafted LLDPE available from E. I. duPont de Nemours &
Co., Wilmington, DE U.S.A.
CA maleic anhydride functionali~d EPDM.
The LCP used was a polymer of the following monomers in the bracketed molar
ratios; 4,4'-biphenol(26.3)/hydroquinone(26.3)/1 ,6-hP~r~n~ nline(47.4)lterephthalic
acid(36.8)/2,6-n~phth~lene dicarboxylic acid(63.2)/4-hydro~ybcl~oic acid(89.5)/6-
hydroxy-2-napthoic acid(36.8). Melting point (DSC) of this LCP was 265~C.
2s The film was used as a "lid" of an al~ it.~ cup co~ ing ethylene glycol:
water mixture (a used ~1:1 ratio of commercial automotive ~llirl~e~e and water, radiator
fluid), secured between metal rings and gaskets to avoid leakage and was placed in the
inverted position ( so that the li~uid would contact the film) in an oven at 100 C.
Periodically, the cup was removed from the oven, cooled and weighed and placed back in
the oven. The repeated cooling and reh~tin~ made the film concave or convex because
of the pressure differences inside the cup as a consequence of the le~ ,e~ c variations.
1 CA 02263603 1999-02-22
This induces another repeated fatigue stress which can be qualitatively observed, but was
not measured.
Evaluation of this film~ at 60~C, showed a fluid loss of 12.6 g/m~/day (0.~1
gm/100 in~/day). A film (0.19 mrn thick) of nylon-6,6 blended with synthetic rubber
(Nordel~ 3681) and functionalized synthetic rubber (which is a maleic anhydride grafted
EPDM) in an 80/10/10 weight ratio respectively (an also contains less than 1 weight
per-ent of an epoxy resin), showed a lo~s of 159 g/m'lday (10.27 gm/100 in~/day) under
the same conditions.
EXAl~IPLE 4
o Tubing was extruded with the following configuration (inside to outside of tube)
and outer diameter 3.6 mm;
inside layer LCP 0.05 mm
middle layer XB603 0.05 mm
outer layer nylon 6.6 0.075 mm
The LCP used was a polymer of the following monomers in the bracketed molar
ratios; 4,4'-biphenol(35.5)/hydroquinone(35.5)/1,6-hexane~i~mine(29.0)/terephthalic
acid(60)12,6-naphthalene dicarboxylic acid(40)/4-hydroxybenzoic acid(l30). The melting
point (DSC) of this LCP was 255~C.
~o Evaluation as per Exarnple 1 at 38~C showed a loss of 0.02 gm/100 in'/day; nylon
6,6 tubing of the same dimensions showed a loss of 2.04 gm/100 in~/day.
Example S
For this example a coextruded 3-layer film was used. When coextruded, the melt
temperature of the inner layer was 269~C, while the melt temperature of the outer layers
was 292~C, and the line speed was 14.5 m/min. The inner layer, which was 0.076 mm
thick, was Bynel~) 4006 (this is a maleic anhydride modified high density polyethylene
with a melt index of 0.6, available from E. I. DuPont de Nemours & Co., Wilmington,
DE, U.S.A.) The two outer layers were the same polymer used for layer 1 of Example 3,
and each outer layer was 0.057 mm thick. The film was corona treated on both sides to
about 4.8xlO~ N/cm (48 dynes/cm).
The film was formed into heat exchanger panels consisting or 13 rectangularly
shaped liquid flow channels with manifolds on each end, and each panel had a primary
AIVI~NOED SltE~T
CA 02263603 1999-02-22
W O 98110927 PCT/CA97/00647
heat exchange surface area about 54 cm long and 5 cm wide. Panels (67) were stacked
by joining the manifolds, al~d the primary heat eYch~nge surface of the stack was
ex~ AIPd to be 33,626 cm2.
A similar heat exchanger was made from single layer film 0.19 mm thick of the
5 same polymer of the outer layers of the above heat e~rch~nger. This 69 panel heat
exçl~ e. had a surface area of about 34,632 cm2.
Both of these heat e~rh~n~ers were tested using 77~C water. The heat exchanger
constructed from the 3-layer film had a water loss of 0.17 g/hr, while the heat ex~h~nger
constructed from the single layer film had a water loss of 1.1 glhr.
o Example 6
Polymer A was a liquid crystalline polymer which was an aromatic polyester, and
was a copolymer of (molar ratios in parenth~ses): 4,4'-
biphenol(26.3)/hydroquinone(26.3)/1,6-hexdne~ minP(47.4)/terephthalic acid(36.8)/2,6-
n~rhth~1ene dicarboxylic acid(63.2)/4-hydroxybenzoic acid(~9.5)/6-hydroxy-2-napthoic
acid(36.8).
Polymer B was a nylon 6/Sclair(~ 1 lKl~/Fusabond~) D226b/a functionalized
synthetic rubbef (72.5/13.6/6.816.8 weight percent (3LLDPE available from Nova
Chemicals, Calgary, Alberta, Canada, bA maleic anhydride grafted LLDPE availablefrom E. I. duPont de Nemours & Co., Wilmington, DE U.S.A.; CA maleic anhydride
20 function~li7~(~ EPDM.)
Polymer C was a blend prepared in a twin screw extruder of 40 percent by weight
of Polymer A and 60 percent by weight of Polymer B.
The a~dlus used included a 3/4" (1.91 cm) Brabender (Type 2003, C. W.
Brabender Instruments, H~c~ s~c~ NJ, U.S.A.), a 1" (2.54 cm) Wilmod extruder, and a
25 3.8 cm NRM extruder. Polymer A was extruded from the Wilmod extruder running at 45
rpm and the melt te~ cldlure was 280~C. Polymer B was extruded from the NRM
extruder running at 20 rpm and at a melt lell~y~dlule of 280~C. Polymer C was extruded
from the Brabender extruder running at 60 rpm and with a melt ~elll~ldlul~ of 270~C.
The output of each of these extruders was fed to 15.2 cm wide film die which was30 configured to handle three se~Jdld~e feeds. Polymers A and B were the outside layers and
Polymer C was the inner layer.
CA 02263603 1999-02-22
W 0 98/10927 PCT/CA97/00647
The molten film fell by gravity on the oscill~ting rollers, which were arranged as
shown in Fig. 1. The rollers were 8.9 cm in diarneter and 20.3 cm wide, and the surfaces
were faced with stainless steel which were embossed with a diamond or knurled pattern,
about 50-75 ,um deep, with a 90~ included angle for the sides, with the knurling lines at
s an angle of 30~ to the axis of rotation of the roll. The rotational speeds of the rollers
were m~nl-~lly controlled using a variable speed drive motor and was set so the surface
speed of the rolls was 6m/min. The rate of oscillation was also m~nll~lly controlled by a
variable speed drive motor and was 50 Hz, while the amplitude of oscillation could be
varied by ch~nging the cam 17, and was 1.3 mm. Each roller was individually heated by
0 Calrod~ electrical heaters, which were in turn ~lltom~tically controlled by digital
controllers. It is believed that the roller t~ pcldLuies could be ..~ e~ to about +1~C,
and the roller telll~ dlu~cs were 1 77~C. Afte} passing through the oscill~ting rollers the
film was passed through a set of cooling rolls and then rolled up on a roll.
In the beginning of the run, the speed of extrusion and rotation of the oscillating
S rollers were adjusted so that a rolling bank ofthe polymer built up on the oscill:~ting
rollers, and then the speed of the osçill~ting rollers was set as closely as possible to
m~int~in a cQmt~nt sized rolling bank. Occasionally some manual adj--ctTnentc were
needed.
In the resulting film, the Polymer a layer was about 0.051 mm thick, the PolymerB layer was about 0.10 mrn thick and the Polymer C layer was about 0.051 mm thick.
Using the above three-layer film, heat e~ch~n~er panels were made using the
procedure of Example 2 of U.S. Patent 5,050,671, as described below.
The sheets were coated on the Polymer B side with a solution of benzyl alcohol
and phenol, as described in U.S. Patent 4,935,462. The coated sides were placed in face-
25 to-face contact, between female molds co~ ;; ~,g grooves parallel to the long axis of the
sheets, with inlet and outlet headers at each end of the sheets. The molds were then
heated in a press at 160~C and 241 MPa p-~S~UIc was applied while nitrogen gas was
passed b~Lwt;en the sheets so that each sheet conformed to the shape of the grooves, the
two sheets were bonded together, and the headers were bonded to the ends of the sheets.
No fractures or tears were evident in the resulting panel in the outer s~ cçs (which were
Polymer A). The headers of several of these panels were bonded together to form a heat
exchanger.
14
.. .. .
CA 02263603 1999-02-22
WO 98/10927 PCTtCA97/00647
An otherwise i~lPntic~l heat e~h~neer was made from 0 2 mm thick sheeting of
Polymer B (the ~hçetine didn't go through the oscillating rollers). Water at 70~C was
passed through the two heat ex~h~neers, and the rate of water loss by diffusion through
the panels ~ d. The rate of water loss for the heat çxl~h~ngPr made with the three-
5 polymer layer panels was 0.8 g/hr more than 10 times less than that of the heat çxrh~ngermade from Polymer B alone which lost about 9.1 g~r of water.
