U.S. patent number RE30,321 [Application Number 05/893,315] was granted by the patent office on 1980-07-01 for mineral oil extended polyurethane system containing a coupling agent for decontaminating and sealing the interior spaces of an insulated electrical device.
This patent grant is currently assigned to N L Industries, Inc.. Invention is credited to Melvin Brauer, Thaddeus F. Kroplinski.
United States Patent |
RE30,321 |
Brauer , et al. |
July 1, 1980 |
Mineral oil extended polyurethane system containing a coupling
agent for decontaminating and sealing the interior spaces of an
insulated electrical device
Abstract
This invention provides a method of sealing and purging
contaminants from the internal free spaces of an insulated
electrical device by forcing into said free spaces a low viscosity
material that acts to displace fluid contaminants from within said
free spaces. The material later cures in situ to form a hydrophobic
seal with good electrical properties. Also disclosed herein is a
method for rehabilitating waterlogged plastic insulated
multiconductor communications cables of the type employed in
telephone systems.
Inventors: |
Brauer; Melvin (East Brunswick,
NJ), Kroplinski; Thaddeus F. (Bound Brook, NJ) |
Assignee: |
N L Industries, Inc. (New York,
NY)
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Family
ID: |
27029507 |
Appl.
No.: |
05/893,315 |
Filed: |
April 3, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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432479 |
Jan 11, 1974 |
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Reissue of: |
632180 |
Nov 17, 1975 |
04008197 |
Feb 15, 1977 |
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Current U.S.
Class: |
528/361 |
Current CPC
Class: |
C08G
18/69 (20130101); C08G 18/755 (20130101); C08K
5/01 (20130101); H01B 3/302 (20130101); C08K
5/01 (20130101); C08L 75/04 (20130101) |
Current International
Class: |
C08G
18/00 (20060101); C08K 5/00 (20060101); C08K
5/01 (20060101); C08G 18/75 (20060101); C08G
18/69 (20060101); H01B 3/30 (20060101); C08K
005/01 (); C08K 005/07 (); C08K 005/10 () |
Field of
Search: |
;260/33.6UB,31.2N,31.8H,31.8C,31.6,30.6,32.8N,18TN |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1806783 |
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May 1970 |
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DE |
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121553 |
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Mar 1971 |
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NO |
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Primary Examiner: Lieberman; Allan
Attorney, Agent or Firm: Mandros; Platon N. Sutherland;
Malcolm L. Nath; Gary M.
Parent Case Text
This application is a continuation-in-part of our patent
application Ser. No. 432,479 filed on Jan. 11, 1974 and now
abandoned.
Claims
We claim:
1. A .Iadd.cured, cross-linked, .Iaddend.mineral oil extended
polyurethane .[.system.]. comprising the reaction product of an
isocyanate terminated prepolymer with a polyol .Iadd.selected from
the group consisting of castor oil, polyether polyols, hydroxyl
bearing homopolymers of butadiene, hydroxyl bearing copolymers of
butadiene and styrene, and combinations thereof, .Iaddend.in the
presence of a mineral .Iadd.oil .Iaddend.and a liquid coupling
agent for compatibilizing said mineral oil with said polyurethane,
said .Iadd.mineral oil extended .Iaddend.polyurethane .[.system.].
containing from about 8 to about 20 parts of .[.said urethane
polymer.]. .Iadd.polyurethane.Iaddend., from about 60 to about 75
parts mineral oil and from about 10 to about 25 parts of
.[.coupler.]. .Iadd.coupling agent.Iaddend., all parts expressed on
a weight basis, said liquid coupling agent being miscible in all
proportions with said mineral oil, said coupling agent .Iadd.being
.Iaddend.selected from the group consisting of a ketone and an
ester .[.of an organic compound selected from the group consisting
of a diol and a diacid.]., said agent having a boiling temperature
above 220.degree. F., a solubility parameter between 7.0 and 9.5
and a hydrogen bonding index number in the range from .[.8.2 to
8.8.]. .Iadd.6.0 to 12.0, and said agent being non-reactive with
the prepolymer and the polyol.Iaddend., said isocyanate terminated
prepolymer .Iadd.being prepared by reacting a polyisocyanate
.Iaddend.selected from the group consisting of cycloaliphatic
diisocyanate, aliphatic diisocyanate and aromatic diisocyanate .[.;
said.]. .Iadd.with a .Iaddend.polyol selected from the group
consisting of castor oil.Iadd., .Iaddend..[.and.]. polyether
.Iadd.polyols, hydroxyl bearing homopolymers of butadiene, hydroxy
bearing copolymers of butadiene and styrene, and combinations
thereof .Iaddend.wherein at least .[.one of said urethane forming
reactants include a hydroxy bearing polybutadiene constituent.].
.Iadd.a portion of the polyol used in the preparation of the
polyurethane is selected from the group consisting of hydroxyl
bearing homopolymers of butadiene and hydroxyl bearing copolymers
of butadiene and styrene.Iaddend., the mineral oil extended
polyurethane when cured retaining the mineral oil within its
structure, thereby preventing the oil from spewing and exuding from
said cured composition.[., said composition possessing a gel-like
consistency.]..
2. .[.Product according to.]. .Iadd.The cured, cross-linked,
mineral oil extended polyurethane of .Iaddend.claim 1 in which the
mineral oil employed is paraffin oil.
3. .[.Product according to.]. .Iadd.The cured, cross-linked,
mineral oil extended polyurethane of .Iaddend.claim 1 in which the
liquid coupling agent is 2,2,4-trimethyl .Badd..[.1,1,3-pentane
diol.]..Baddend. .Iadd.1,3 pentanediol .Iaddend.diisobutyrate.
4. .[.Product according to.]. .Iadd.The cured, cross-linked,
mineral oil extended polyurethane of .Iaddend.claim 1 in which the
coupling agent is di-2 ethyl hexyl adipate.
5. .[.Product according to.]. .Iadd.The cured, cross-linked,
mineral oil extended polyurethane of .Iaddend.claim 1 wherein said
isocyanate terminated prepolymer is the reaction product of
.Badd..[.3-isocyanatoemethyl.]..Baddend. .Iadd.3-isocyanato-methyl
.Iaddend.3,3,5-trimethylcyclohexyl isocyanate and a liquid hydroxyl
terminated homopolymer of butadiene.
6. A .Iadd.cured, cross-linked, .Iaddend.mineral oil extended
polyurethane .[.system.]. comprising the reaction product of an
isocyanate terminated prepolymer with a polyol .Iadd.selected from
the group consisting of castor oil, polyether polyols, hydroxyl
bearing homopolymers of butadiene, hydroxyl bearing copolymers of
butadiene and styrene, and combinations thereof, .Iaddend.in the
presence of a mineral oil and a liquid coupling agent for
compatibilizing said mineral oil with said polyurethane, said
.Iadd.mineral oil .Iaddend.extended polyurethane .[.system.].
containing from about 8 to .Iadd.about .Iaddend.45 parts of
polyurethane .[.said urethane polymer.]., from about 25 to about 75
parts mineral oil and from about 10 to about 35 parts of
.[.coupler.]. .Iadd.coupling agent.Iaddend., all parts expressed on
a weight basis, said liquid coupling agent being miscible in all
proportions with said mineral oil, said coupling agent selected
from the group .[.consiting.]. .Iadd.consisting .Iaddend.of a
ketone and an ester .[.of an organic compound selected from the
group consisting of a diol and a diacid.]., said agent having a
boiling temperature above 220.degree. F., a solubility parameter
between 7.0 and 9.5 and a hydrogen bonding index number in the
range from .Badd..[.8.2 to 8.8.]..Baddend., .Iadd.6.0 to 12.0 and
said agent being non-reactive with the prepolymer and the polyol,
.Iaddend.said isocyanate terminated prepolymer .Iadd.being prepared
by reacting a polyisocyanate selected from the group consisting of
cycloaliphatic diisocyanate, aliphatic diisocyanate and aromatic
diisocyanate with a polyol .Iaddend.selected from the group
consisting of castor oil .[.and.]..Iadd., .Iaddend.polyether
.Iadd.polyols, hydroxyl bearing homopolymers of butadiene, hydroxyl
bearing copolymers of butadiene and styrene, and combinations
thereof, .Iaddend.wherein at least .[.one of said urethane forming
reactants include a hydroxy bearing polybutadiene constituent.].
.Iadd.a portion of the polyol used in the preparation of the
polyurethane is selected from the group consisting of hydroxyl
bearing homopolymers of butadiene and hydroxyl bearing copolymers
of butadiene and styrene.Iaddend., the mineral oil extended
polyurethane when cured retaining the mineral oil within its
structure, thereby preventing the oil from spewing and exuding from
said cured composition.[., said composition possessing a gel-like
consistency.]..
7. A .Iadd.cured, cross-linked, .Iaddend.mineral oil extended
polyurethane .[.system.]. comprising the reaction product of an
isocyanate terminated prepolymer with a polyol .Iadd.selected from
the group consisting of castor oil, polyether polyols, hydroxyl
bearing homopolymers of butadiene, hydroxyl bearing copolymers of
butadiene and styrene, and combinations thereof, .Iaddend.in the
presence of a mineral oil and a liquid coupling agent for
compatabilizing said mineral oil with said polyurethane, said
.Iadd.mineral oil extended .Iaddend.polyurethane .[.system.].
containing from about 20 to about 45 parts of .[.said urethane
polymer.]. .Iadd.polyurethane.Iaddend., from about 25 to about 60
parts mineral oil and from about 25 to about 35 parts of
.[.coupler.]. .Iadd.coupling agent.Iaddend., all parts expressed on
a weight basis, said liquid coupling agent being miscible in all
proportions with said mineral oil, said coupling agent .Iadd.being
.Iaddend.selected from the group consisting of a ketone and an
ester .[.of an organic compound selected from the group consisting
of a diol and diacid.]., said agent having a boiling temperature
above 220.degree. F., a solubility parameter between 7.0 and 9.5
and a hydrogen bonding index number in the range from .Badd..[.8.2
to 8.8.]., .Iadd.6.0 to 12.0 and said agent being non-reactive with
the prepolymer and the polyol, .Iaddend.said isocyanate terminated
prepolymer .Iadd.being prepared by reacting a polyisocyanate
.Iaddend.selected from the group consisting of cycloaliphatic
diisocyanate, aliphatic diisocyanate and aromatic diisocyanate.[.;
said.]. .Iadd.with a .Iaddend.polyol selected from the group
consisting of castor oil .[.and.]..Iadd., .Iaddend.polyether
.Iadd.polyols, hydroxyl bearing homopolymers of butadiene, hydroxyl
bearing copolymers of butadiene and styrene, and combinations
thereof, .Iaddend.wherein at least .[.one of said urethane forming
reactants include a hydroxy bearing polybutadiene constituent.].
.Iadd.a portion of the polyol used in the preparation of the
polyurethane is selected from the group consisting of hydroxyl
bearing homopolymers of butadiene and hydroxyl bearing copolymers
of butadiene and styrene.Iaddend., the mineral oil extended
polyurethane when cured retaining the mineral oil within its
structure, thereby preventing the oil from spewing and exuding from
said cured composition.[., said composition being useful as a
casting system.]..
8. .[.Composition according to.]. .Iadd.The cured, cross-linked,
mineral oil extended polyurethane of .Iaddend.claim 1 which
.[.preferably contains.]. .Iadd.comprises from .Iaddend.about 121/2
to about 15 parts by weight of .[.said urethane polymer.].
.Iadd.polyurethane, from .Iaddend.about 65 to about 70 parts
.Iadd.by weight .Iaddend.of mineral oil and from about 15 to about
20 parts by weight of .[.coupler.]. .Iadd.coupling agent.Iaddend..
.Iadd.
9. The cured, cross-linked, mineral oil extended polyurethane of
claim 1 wherein said coupling agent has a hydrogen bonding index
number in the range from 8.2 to 8.8. .Iaddend. .Iadd.10. The cured,
cross-linked, mineral oil extended polyurethane of claim 6 wherein
said coupling agent has a hydrogen bonding index number in the
range from 8.2 to 8.8. .Iaddend. .Iadd.11. The cured, cross-linked,
mineral oil extended polyurethane of claim 7 wherein said coupling
agent has a hydrogen bonding index number in the range from 8.2 to
8.8. .Iaddend. .Iadd.12. A cured, cross-linked, mineral oil
extended polyurethane which is non-spewing comprising:
(a) from about 8 to about 45 parts, by weight, of polyurethane,
said polyurethane being prepared by reacting
(i) a polyisocyanate prepolymer prepared by the reaction of a
polyisocyanate with a polyol selected from the group consisting of
castor oil, polyether polyols, hydroxyl bearing homopolymers of
butadiene, hydroxyl bearing copolymers of butadiene, and
combinations thereof, with
(ii) a polyol selected from the group consisting of castor oil,
polyether polyols, hydroxyl bearing homopolymers of butadiene,
hydroxyl bearing copolymers of butadiene, and combinations
thereof;
(b) from about 25 to about 75 parts, by weight, of mineral oil,
(c) from about 10 to about 35 parts, by weight, of coupling agent,
said coupling agent being characterized by
(i) being miscible in all proportions with said mineral oil,
(ii) having a solubility parameter between 7.0 and 9.5,
(iii) having a hydrogen bonding index number in the range of from
6.0 to 12.0, and
(iv) being non-reactive with the prepolymer and the polyol, and
wherein the cured, cross-linked polyurethane is characterized by
the presence of a polybutadiene moiety in the polyurethane
structure.
.Iaddend. .Iadd.13. The cured, cross-linked, mineral oil extended
polyurethane of claim 12 wherein said coupling agent is selected
from the group consisting of a ketone and an ester. .Iaddend.
.Iadd.14. The cured, cross-linked, mineral oil extended
polyurethane of claim 13 wherein said polyisocyanate is selected
from the group consisting of cycloaliphatic diisocyanate, aliphatic
diisocyanate and aromatic diisocyanate. .Iaddend.
.Iadd.15. The cured, cross-linked, mineral oil extended
polyurethane of claim 14 wherein said coupling agent is further
characterized by having a boiling temperature above 220.degree. F.
.Iaddend. .Iadd.16. The cured, cross-linked, mineral oil extended
polyurethane of claim 15 wherein said coupling agent has a hydrogen
bonding index number in the range of from 8.2 to 8.8. .Iaddend.
.Iadd.17. The cured, cross-linked, mineral oil extended
polyurethane of claim 15 wherein one of the polyols of claim
12(a)(i) and (a)(ii) is castor oil. .Iaddend. .Iadd.18. The cured,
cross-linked, mineral oil extended polyurethane of claim 15 wherein
the polyols of claim 12(a)(i) and (a)(ii) are selected from the
group consisting of hydroxyl bearing homopolymers of butadiene,
hydroxyl bearing copolymers of butadiene and styrene, and
combinations thereof. .Iaddend. .Iadd.19. The cured, cross-linked,
mineral oil extended polyurethane of claim 15 wherein said mineral
oil is a paraffin oil. .Iaddend. .Iadd.20. The cured, cross-linked,
mineral oil extended polyurethane of claim 15 which comprises from
about 8 to about 20 parts of polyurethane, from about 60 to about
75 parts of mineral oil and from about 10 to about 25 parts of
coupling agent, all parts expressed on a weight basis.
.Iaddend.
.Iadd. The cured, cross-linked, mineral oil extended polyurethane
of claim 15 which comprises from about 20 to about 45 parts of
polyurethane, from about 25 to about 60 parts of mineral oil and
from about 25 to about 35 parts of coupling agent, all parts
expressed on a weight basis. .Iaddend. .Iadd.22. The cured,
cross-linked, mineral oil extended polyurethane of claim 15 which
comprises from about 121/2 to about 15 parts of polyurethane, from
about 65 to about 70 parts of mineral oil and from about 15 to
about 20 parts of coupling agent, all parts expressed on a weight
basis. .Iaddend. .Iadd.23. A cured, cross-linked, mineral oil
extended polyurethane which is non-spewing comprising from about 8
to about 45 parts of polyurethane, from about 25 to about 75 parts
of mineral oil and from about 10 to about 35 parts of coupling
agent, all parts expressed on a weight basis, wherein the cured,
cross-linked polyurethane is characterized by the presence of a
polybutadiene moiety in the polyurethane structure and is prepared
from a mineral oil extended polyurethane precursor in admixture
with the coupling agent, said coupling agent being characterized
by:
(a) possessing a solubility parameter between 7.0 and 9.5;
(b) having a hydrogen bonding index number in the range of 6.0 to
12.0;
(c) being miscible in all proportions with said mineral oil;
and
(d) being non-reactive with said polyurethane precursor.
.Iaddend.
.Iadd. The cured, cross-linked, mineral oil extended polyurethane
of claim 23 wherein the polybutadiene moiety is derived from at
least one member of the group consisting of hydroxyl bearing
homopolymers of butadiene and hydroxyl bearing copolymers of
butadiene and styrene. .Iaddend. .Iadd.25. The cured, cross-linked,
mineral oil extended polyurethane of claim 24 wherein said coupling
agent is further characterized by having a boiling temperature
above 220.degree. F. .Iaddend.
Description
This invention relates to a method of rehabilitating insulated
electrical devices that have been contaminated by fluid penetration
of their interior free spaces. More specifically, the invention
concerns a method for displacing aqueous fluid penetrants from the
interior free spaces of an insulated electrical apparatus and
sealing the purged spaces against further aqueous fluid penetration
while maintaining the electrical properties of the apparatus.
Water penetration of insulated electrical devices and especially
plastic insulated multiconductor telephone cables can seriously
effect the electrical properties of such structures. The problem of
water penetration is amplified when the electrical device is
positioned underground or in a high humidity environment. In the
case of a telephone cable, water penetration can seriously impair
the electrical and mechanical .[.improperties.]. .Iadd.properties
.Iaddend.that are critical to its continued operation. The pressure
of water between insulated conductors can cause a significant
increase in their capacitance and can lead to the development of
electrical leakage pathways between conductors having pinhole
insulation defects. Leakage of water into the unoccupied spaces
between the insulated cable pairs and the outer sheath can also
cause a significant increase in signal attenuation, noise, and lead
to conductor corrosion.
Replacement of waterlogged cables is not a satisfactory solution to
the problem of water contamination in most cases because of the
expense and inconvenience involved in such an undertaking. However,
in order to maintain suitable operating parameters the cable must
be rehabilitated by removal of the fluid contaminant and
restoration of the electrical and mechanical conditions that render
it useful as a means for transmission of telephone signals.
The prior art has advanced several methods of eliminating aqueous
penetrants from the interior free spaces of plastic insulated
conductor cables. One technique involves the use of acetone to
eliminate water. Removal of water, alone, is not sufficient in most
cases since the means for water penetration is not eliminated and
unless a continuous supply of acetone is maintained in the cable,
renewed fluid penetration can be expected to occur. Another method
of purging water contaminants depends upon pumping a gas into the
interior free spaces of the cable via a coupling to the outer cable
sheath and maintaining a continuous elevated gas pressure between
interconnected cable segments. This method is impractical for use
in most cases since it requires the continued operation of a gas
generating source in order to prevent subsequent water
penetration.
A recently developed technique removes water that has penetrated
into the interior free spaces of a telephone cable by pumping a
hydrophobic insulating material into the cable. The insulating
material is introduced at low viscosity and cures in place to a
high viscosity thus precluding its escape via defects in the outer
covering of the cable. The cured material simultaneously acts as a
hydrophobic barrier to subsequent water penetration. This system
employs a cross-linking composition which is a solution of a liquid
urethane elastomer in an aromatic oil. A principal disadvantage of
this system is that after the reclamation agent has cured in place,
the aromatic hydrocarbon oil can escape from the cross-linked
system and severely attack the plastic conductor connectors, or
polyolefin sheathing.
In addition to the water elimination, low viscosity, and barrier
properties previously set forth a rehabilitation material for use
in sealed electrical devices must fulfill other critical
requirements. It must be compatible with plastic connectors (such
as polycarbonates), normally employed in joining lengths of
telephone cable. .[.compatibility.]. .Iadd.Compatibility
.Iaddend.with polyolefins is important and an effective
rehabilitation agent should not stress crack these materials which
frequently form the insulating sheath of telephone cables. The
agent should also have good mechanical properties, relatively long
life expectancy and a relatively flat viscosity-time curve to
insure good pumpability and to enable longer cable segments to be
rehabilitated and filled in a single application.
It is also important that a cable rehabilitation agent display
superior electrical characteristics such as high insulation
resistance, volume resistivity dissipation factor and low
dielectric constants since in most cases it must rehabilitate the
cable with respect to these properties. Additionally, the
reclamation agent should have a low specific gravity in order to
impart a minimal weight gain to he rehabilitated cable and less
water and air entrapment which can result from the turbulence
effects of pumping into a confined cable space. Also, the
rehabilitation compound should not attack polyethylene
terephthalate or other synthetic polymer materials employed in
cable construction.
Finally, current health and safety regulations make it imperative
that a rehabilitation agent be relatively non-toxic, non-volatile
and easy to handle in the field.
It is therefore an object of this invention to provide a method of
eliminating water that has penetrated the interior free spaces of
an insulated electrical apparatus and to simultaneously provide a
barrier to prevent subsequent water penetration.
Another object of the invention is to rehabilitate the electrical
properties of an insulated electrical apparatus that has become
waterlogged.
A further aspect of the invention is to dislodge aqueous
contaminants from the interior free spaces of a plastic insulated
multiconductor telephone cable by introduction of a cable
rehabilitation compound under .[.pressue.]. .Iadd.pressure
.Iaddend.over lengthy cable spans in a single operation.
Another aspect of this invention is the provision of a low
viscosity agent capable of eliminating aqueous contaminants from
the interior free spaces of an insulated electrical cable and which
cures in situ to provide a permanent barrier to subsequent water
penetration.
These and other objects of the instant invention will be better
understood by reference to the following specification and the
accompanying drawing wherein:
FIG. 1 is a front elevational view, partly in section, of a length
of plastic insulated multi-conductor telephone cable.
The generic aspect of the instant invention involves a method of
eliminating water that has penetrated the interior free spaces of
an insulated electrical apparatus by forcing into the free spaces
of the apparatus a rehabilitation agent comprising a low viscosity
solution of urethane precursors that are extended in a mineral oil.
The rehabilitation agent is introduced into the apparatus at very
low viscosity by pumping. Continuous introduction of the low
viscosity agent is maintained in order to drive it along the length
of the free spaces throughout the electrical apparatus. The
rehabilitation compound initially displaces aqueous contaminants,
such as water, that have penetrated into the interior free spaces
between the different components of the insulated device.
Thereafter, the low viscosity agent cures in situ to form a
gel-like urethane structure in which the mineral oil is retained.
In this manner, water contaminants are removed from the insulated
electrical arrangement, a barrier is formed against further water
penetration and the electrical properties of the device are
restored. This technique is especially useful in the rehabilitation
of plastic insulated conductor cables.
A specific embodiment of this invention employs a two-component
urethane cable rehabilitation agent extended with a mineral oil.
Polyurethanes, being very polar elastomers, were heretofore thought
to be almost completely incompatible with the non-polar minerals
oils and extension of urethanes was traditionally accomplished with
aromatic oils. Although the prior art has been able to achieve some
extension of polyurethanes using mineral oils, these efforts have
been limited to relatively low extension ratios of about 2:1, oil
to polymer. At higher extension ratios these prior art systems
begin to lose their oil contents by exudation (or spewing) shortly
after cure. We have found that the coupler is necessary in our
systems .[.which comprises castor oil, polyether polyols in
combination with hydroxyl bearing polybutadiene and a
diisocyanate.]. to obtain stable non-spewing elastomeric materials
with extensions even as low as 1:1 and up to 10:1 if desired.
Without the coupler the elastomer spews oil.
For purposes of this specification, mineral oils are considered to
be those aliphatic, cycloaliphatic, and branched aliphatic
saturated hydrocarbons that contain from 15-20 C atoms and are
distilled from petroluem. Included in this classification are
naphthenic and paraffin oils. Paraffin oils are the preferred
mineral oil for use in this invention. In the instant invention it
was unexpectedly found that a cross-linkable low viscosity solution
of a mineral oil, a preselected polyol and a preselected isocyanate
prepolymer, in which either the prepolymer or the polyol
constituent contain a polybutadiene moiety can be prepared through
the use of liquid coupling agents that are preferably high boiling
esters of organic diacids or diols. More specifically the coupling
agents may be saturated or unsaturated, (preferably
.[.unsaturated.]. .Iadd.saturated.Iaddend.) aromatic-aliphatic,
cyclo-aliphatic or wholly aliphatic esters, such as 2,2,4-trimethyl
1,3-pentane diole diisobutyrate. Other suitable liquid coupling
agents include those in which a polar group is attached to an
alkane structure, such as, for example, tributyl phosphate.
In order to effectively compatibilize the mineral oil with a
cross-linking urethane elastomer, it has been discovered that a
coupler must satisfy several criteria. Firstly, it must be soluble
in mineral oils in all proportions. In other words, the coupler
should be miscible in all proportions with mineral oils to form a
true solution (i.e., one part coupler/99 parts mineral oil or 99
parts coupler/one part mineral oil). It has also been found that
coupler compounds suitable for use in this invention have a
solubility parameter (.delta.) in the range of 7.0-9.5 and a
hydrogen bond index number within the range 6 to 12.
The (.delta.) value of a substance is calculated according to the
formula
where .DELTA.E is the energy of vaporization to a gas at zero
pressure (i.e., an infinite separation of the molecules); and
V is the molar volume of component present. The dimensions of
.delta. are (calories per cubic centimeter).sup.1/2. Since it is
possible to ascertain .DELTA.E and V for most substances, the value
of the solubility parameter or .delta. may be calculated from the
heat of varporization .DELTA.H, since it can be shown that
Since the value of .DELTA.H at 25.degree. C. for most compounds may
be found in the literature, this value may be used to calculate
.DELTA.E and then .delta.. Further details on solubility parameters
and means for their calculation are found in an article entitled
Solubility Parmeter Values by H. Burrell and B. Immergut at
P.IV-341, of Polymer Handbook edited by J. Brandrup and E. H.
Immergut, 3rd Edition Interscience Publ., June 1967.
It has also been determined that the coupling agents of this
invention have a hydrogen bond index in the range 6.0-12.0. The
hydrogen bonding index number (.gamma.) of a compound is a
measurement of its proton (hydrogen) attracting power. The hydrogen
bond index number (.gamma.) (proton attracting power) of a compound
is measured by comparing the relative strengths of the hydrogen
bonds which the liquid compounds forms with a common proton or
Deuterium donor.
In practice, this is done by dissolving deuterated methanol in the
liquid to be tested. The proton attracting power of a liquid
compound is determined by measurement of the movement produced on
the OD vibrational band of CH.sub.3 OD. The OD vibrational band
occurs at 4.mu. in the liquid CH.sub.3 OD and at 3.73.mu. in the
monomolecular CH.sub.3 OD in dilute benzene solution. Benzene is
considered to have an OD vibrational shift of 0. The formation of
hydrogen bonds shifts the monomolecular band to lower frequencies
or longer wavelengths. The stronger the proton attracting power of
a liquid, the greater is the shift which it produces on the OD
band. By Infrared Spectroscopy the perturbations of the OD band can
be established.
The .gamma. value of a compound may be determined by measuring the
shift in wave numbers of the OD vibrational band after
.[.disolution.]. .Iadd.dissolution .Iaddend.in the liquid compound
and dividing the resulting number by 10. (Wave number is the
reciprocal of an angstrom unit). Those compounds having a .gamma.
number of 0 to 6.0 are generally acknowledged to be weak hydrogen
bond acceptors. Compounds having index numbers in the range of 6.0
to 12.0 are usually considered moderate hydrogen bond formers and
those having index numbers above 12.0 are considered to be strong
hydrogen bonders. The liquid coupler compounds useful in this
invention are those having a hydrogen bond index number (.gamma.)
falling in the range between 6.0 and 12.0 as determined by the
abovementioned technique. The origin of the Hydrogen Bond index
system and additional details on the means for its computation are
found in a series of articles by W. J. Gordy in J. Chem. Physics,
Vol. VII, pp. 93-99, 1939, Vol. VIII, pp. 170-177, 1940 and Vol.
IX, pp. 204-214, 1941.
Coupler compounds are selected to be non-reactive with the
cross-linkable urethane elastomer composition and accordingly do
not contain any labile hydrogen atoms in their structure.
As indicated above, it is important that the viscosity of the
solvent, coupler and polymer solution be kept to a minimum in order
to effect their introduction into the free spaces of a cable that
is to be reclaimed. However, the amount of polymer in the
rehabilitation composition should also be minimized to the greatest
extent possible in order to prevent excessive weight gain in the
apparatus to be rehabilitated as well as for reasons of
economy.
In order to provide suitable mechanical and electrical properties
for reclamation of insulated electrical devices, within a
reasonable period of time at ambient temperature, the gelled
paraffinic oil extended elastomer system should be cross-linked.
Cross linking is obtained by use of either an isocyanate or a
polyol, more usually a polyol having a functionality of between 2.0
and 3.0, and preferably 2.2-2.7. Also, the volume resistivity of
the paraffin extended polyurethane as determined by ASTM D-257
should be at least 2.5.times.10.sup.10 ohm-cm and preferably
higher.
The instant mineral oil extended rehabilitation compounds are
preferably prepared on the site by admixing the contents of two
separate containers. In this manner instruction of personnel in the
formulation and use of the rehabilitation material is facilitated
because the contents of the two containers are preferably mixed in
approximately equal proportions just prior to their introduction
into the apparatus to be reclaimed. If necessary, all the
individual ingredients can be admixed together on the site.
In one container is an isocyanate terminated prepolymer, preferably
in mineral oil solution. Between about 50 and 200, and preferably
about 100 grams of isocyanate prepolymer is employed per liter of
solution in the first container. The prepolymer is preferably
formed from a cycloaliphatic diisocyanate such as, for example,
3-isocyanato methyl, 3,5,5-trimethylcyclohexy isocyanate (IPDI).
The useable isocyanates for making the prepolymers in this
invention also include the aliphatic and aromatic diisocyanates
such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane
diisocyanate (MDI), 1,5-naphthalene diisocyanate, phenylene
diisocyanates, or mixtures of these materials, 4,4'-methylene
bis(cyclohexyl isocyanate) and hexamethylene diisocyanate, as well
as related aromatic and aliphatic isocyanates, which may also be
substituted with other organic or inorganic groups that do not
adversely affect the course of the chain-extending and/or
cross-linking reaction.
Formation of the isocyanate terminated prepolymer is accomplished
by reacting an excess-of one of the preceding isocyanate components
with a polyol having a relatively high molecular weight of between
about 1,000 and 6,000. Among the polyols useful in formation of the
isocyanate terminated prepolymer are those selected from compounds
based essentially on polybutadiene, castor oil or hydroxyl bearing
polyethers or conbinations of them.
Suitable polyether polyols include aliphatic alkylene glycol
polymers exemplified by polypropylene ether glycol and poly 1-4
butylene ether glycol. Also trifunctional compounds exemplified by
the reaction product of trimethylol propane and propylene oxide may
be employed as the polyol constituents.
The polybutadiene based polyols are liquids that are founded on
hydroxyl terminated liquid butadiene homopolymers and hydroxyl
terminated butadiene copolymers with styrene. A typical butadiene
based polyol copolymer has the approximate structure ##STR1##
wherein X is C.sub.6 H.sub.5 for a styrene-butadiene copolymer
and
a=0.75
b=0.25 and n=57-65
A butadiene homopolymer useful in preparing the isocyanate
terminated prepolymers of the invention has the structure ##STR2##
wherein n=57-65
This class of liquid hydroxy bearing polybutadiene polymers are
available from Arco Chemical Company under the trademark
POLY-BD.
Properties of the hydroxyl-terminated polybutadienestyrene
copolymers are
Butadiene, Wt. %=75
Styrene, Wt. %=25
Viscosity, poise at 30.degree. C.=225
OH content meg./gm=0.65
Moisture--Wt. %=0.05
Iodine Number=335
The prepolymer is preferably formed from the reaction of an excess
of IPDI and the above-mentioned hydroxyl terminated homopolymer of
polybutadiene and has a hydroxyl functionality of 2.2-2.4 and an
equivalent weight of approximately 1260. Another prepolymer
formulation that has been found especially useful in preparing
mineral oil extended cable rehabilitation agents is formed by
reacting an excess of toluene diisocyanate with castor oil or a
hydroxyl terminated polybutadiene homopolymer or a polyether (such
as poly(oxypropylene) glycol of .[.polytetramethylene glycol.].
.Iadd.polytetramethyl ether glycol.Iaddend.. The preferred castor
oil composition for use in preparation of this prepolymer and
generally in this invention comprises a mixture of about 70% pure
glyceryl triricinoleate and about 30% glyceryl
diricinoleatemonooleate or monolinoleate and is available from
Baker Castor Oil, Bayonne, New Jersey, as "DB oil".
In the second container is a solution of between about 75 and 200
and preferably about 150 grams per liter of a preselected polyol in
mineral oil. Suitable polyols with which the polyisocyanate
prepolymers in the first container may be reacted include castor
oil, polyethers such as .[.poly tetramethylene glycol.].
.Iadd.polytetramethylene ether glycol .Iaddend.homopolymers or
copolymers of hydroxy .[.,.]. bearing butadiene, poly
(oxypropylene) glycol or combinations of them.
The mineral oil component may be admixed with either or both of the
prepolymer or polyol stages as long as a sufficient amount of the
liquid coupler agent is present to compatibilize the mineral
component with the respective stage.
The molecular weight (mw.) of the polyols used in this second part
of the system should fall between about 1000 and 6000 and
preferably in the range 2,000-4,000. The molecular weight of the
polyols used to form the prepolymer also lies within the same
range. Preferably, the polyol reactant is a hydroxyl bearing
polymer of either repeating butadiene monomer units or a copolymer
of butadiene and styrene. In fact, it has been determined that in
order to secure effective operation and compatability of a mineral
oil in a urethane elastomer system, either the polyisocyanate
prepolymer or the polyol must include a polybutadiene moiety as
part of their structure. While it is not important whether the
polybutadiene moiety is present in the prepolymer portion or the
polyol precursor of the polyurethane system, it has been determined
that full compatibility of the mineral oil polyurethane system
(especially in highly extended systems) is not obtained absent the
presence of the butadiene moiety in the polyurethane structure.
The mineral oil extended polyurethane is deemed to be a compatible
system since either or both of the prepolymer or the polyol can
accommodate the mineral oil and go on to form a polyurethane
polymer that cures to a gel but does not exude the extender oil
after cure. Accordingly, compatibilizing refers to the ability of
the cured polyurethane system to retain the mineral extender oil
within its structure while remaining in a gel-like consistency.
Once the oil has been compatibilized with the polyurethane
structure it is not lost by spewing or exudation after cure.
Determination as to the proper amount of coupler for use in
compatibilizing a given quantity of mineral oil wih a specific
prepolymer or polyol formulation is best done by experimentation,
although it has been determined that the completed urethane
elastomer system should contain about 8 to about 20 and preferably
between about 121/2 and 15 parts by weight of polymer solids,
between 60 and 75 and preferably between 65 and 70 parts by weight
mineral oil and between about 10 and 25 preferably between about 15
and 20 parts by weight of coupler. In one preferred embodiment a
hydroxy bearing homopolymer of butadiene is reacted with an excess
of 3-isocyanatomethyl 3,5,5 trimethylcyclohexyl isocyanate in the
presence of 2,2,4-trimethyl 1,3, pentanediol diisobutyrate coupling
agent to form a prepolymer which is in turn diluted in mineral oil
and an additional amount of coupler. The dilute prepolymer solution
is then reacted with a dilute solution of the hydroxy bearing
butadiene homopolymer in mineral oil and the same liquid coupling
agent to yield an elastomer system having the following
make-up:
(Polymer) Solids 15 parts by weight
(Extender oil) Paraffin 64 parts by weight
Coupler 20 parts by weight
Catalyst 1 part by weight
The composition ranges cited above cover the preparation of highly
oil extended polyurethanes possessing gel-like consistencies.
However, this invention also covers the preparation of lower oil
extended polyurethane elastomers. The broad ranges therefore
contemplated by the instant invention covering both types of
products comprise from about 8 to about 45 parts by weight of
polymer solids, from about 25 to about 75 parts by weight of
mineral oil and from about 10 to about 35 parts by weight of
coupler.
For the lower oil extended polyurethanes contemplated by the
instant invention which are useful for casting systems for a
variety of potting and encapsulating applications the ranges should
comprise from about 20 to about 25 parts by weight of polymer
solids, from about 25 to about 60 parts by weight of mineral oil
and from about 25 to about 35 parts by weight of coupler.
The liquid couplers employed to compatibilize mineral oils with the
instant polyurethane systems and to secure both high and low
oil/polymer extension ratios according to this invention are
selected according to the previously enumerated criteria.
Generally, the initial criteria is that the coupler liquid must be
soluble in mineral oils in all proportions to form a true
solution.
The coupler compounds will also possess a solubility parameter
(.delta.) between 7.0 and 9.5 preferably in the range between 7.2
and 9.5.
Final evaluation of a coupling agent is usually made with reference
to its hydrogen bonding index (.gamma.) the preferred coupling
agents having hydrogen bonding index numbers in the range 8.2 to
8.8 as determined by the procedures previously set forth. In the
screening of potential coupling agents as determination as to
solubility parameter and hydrogen bonding index number can be made
using well-known analytical techniques. The solubility parameter
value (.delta.) and hydrogen bonding index number (.gamma.) are
available in the literature for many compounds and may be
determined by reference to the appropriate text.
From the chemical standpoint, the couplers are liquids and
preferably esters of organic diacids or diols that boil at
temperatures in excess of 220.degree. F. Other suitable coupling
agents include those liquids in which a polar group is attached to
an alkane structure such as, for example, tributyl phosphate. The
liquid coupling agents may be saturated and unsaturated (although
they are preferably saturated) and may be aromatic-aliphatic,
cyclo-aliphatic, or wholly aliphatic esters, such as for example
2,2,4-trimethyl 1,3 pentanediol diisobutyrate.
The preferred couplers for use in this invention are selected from
amount di-2-ethylhexyl .[.sebecate,.]. .Iadd.sebacate,
.Iaddend.acetyl tributyl citrate, di-2-ethylhexyl adipate, dioctyl
adipate, dibutyl fumarate, di-n-butyl .[.sebecate and.].
.Iadd.sebacate, .Iaddend.di-2-ethylhexyl citrate and acetyl
di-2-ethylhexyl citrate. Especially good results are obtained when
2,2,4-trimethyl-1-3-pentanediol diisobutyrate is employed as the
coupling agent. A list of the principal coupling agents that have
thus far, been found useful in this invention is set forth in Table
A:
TABLE A ______________________________________ COUPLERS (.delta.)
(Cal/ Chemical Name per CC) ______________________________________
.Iadd. 1. 2,2,4 Trimethyl-1,3.Iaddend..[. 1. 2,2,4
Trimethyl-1-1,3.]. Pentanediol Diisobutyrate 8.2 2.
Di-2-ethylhexyl.Iadd.sebacate.Iaddend..[.sebecate.]. 8.6 3. Acetyl
Tributyl Citrate 9.2 4. Di-2-ethylhexyl Adipate 8.7 5. Diisodecyl
Phthalate 7.2 6. Dioctyl Adipate 8.7 7. Tributyl
.[.Phoshate.]..Iadd.Phosphate.Iaddend. 8.6 8. Dibutyl Fumarate 8.5
9. .[.Acetyl Tri-2-ethylhexyl.]..Iadd.Acetyl
Di-2-ethylhexyl.Iaddend. Citrate 8.6 10. Di-n-butyl
.[.Sebecate.]..Iadd.Sebacate.Iaddend. 8.8 11. Dioctyl Phthalate 8.8
12. Di-2-ethylhexyl .[.citrate.]..Iadd.Citrate.Iaddend. 8.6 13.
Isobutyl Acetate 8.4 14. Methyl ethyl Ketone 9.5 15. Methyl-n Butyl
Ketone 8.6 ______________________________________
Selection of a particular coupler determination of the correct
amount to be employed is determined by experimentation and will
vary from one urethane system to another. The selection is
dependent upon chemical and physical differences in various
prepolymers and polyols as well as upon the desired amount of
mineral oil extension in the cured system.
The couplers of this invention enable paraffin oil extensions of up
to about 950% (by weight) based upon polyurethanes, formulated from
polyether diols and triols, castor oil, as well as polybutadiene
polyols and combinations of these. These mineral oil extended
urethane elastomer systems display dielectric constants of 3.4 at
1KHz (as determined by ASTM D-150) or lower. Examples .[.I-XII.].
.Iadd.I-XIII .Iaddend.illustrate the preparation of mineral oil
extended urethane elastomers for use in rehabilitating insulated
electrical devices. Table B outlines the functionality and
molecular weights of the polyols employed in Examples .[.I-XII..].
.Iadd.I-XIII. .Iaddend.
TABLE B
__________________________________________________________________________
Polyol OH Functionality MW
__________________________________________________________________________
1. .Iadd.Polybutadiene.Iaddend..[.Polybudadiene.]. 2.3-2.4
2912-3038 2. Styrene polybutadiene copolymer 2.0 3280 3. Castor oil
2.7 923 4. Polypropylene/glycol 2.0 2040 5. Trimethylolpropane
propylene oxide adduct 3.0 4145 6. .Iadd.Polytetramethylene Ether
Glycol.Iaddend..[.Polytetramethylene Glycol.]. 2.0 2004
__________________________________________________________________________
Table C contains a summary of the important physical and chemical
properties of the Prepolymer components of Examples .[.I-XII..].
.Iadd.I-XIII. .Iaddend.(See Table C attached).
The important physical and electrical properties of the various oil
extended systems prepared in Examples .[.I-XII.]. .Iadd.I-XIII
.Iaddend.are summarized in Table D. (See Table D attached).
Example I illustrates the understanding of the prior art that
polyurethanes, being very polar elastomers are almost completely
incompatible with mineral oils. The results of this example reveals
that a mineral oil cannot be used to obtain a compatible highly
extended polyurethane (i.e., at least about 300% polymer extension)
system in the absence of couplers of the type described in this
invention. Attempts to achieve high degrees of polyurethane
extension with mineral oils and without a suitable coupler result
in an incompatible system which spews oil during and after cure and
is accordingly unsuitable for reclamation of insulated electrical
devices (.e.g, plastic insulated conductor cables, transformers,
capacitors).
EXAMPLE I
a. Prepolymer Formation
A reactor fitted with agitator, thermometer, nitrogen inlet and
reflux condenser was charged with 3120.0 grams (2.5 eq.) of a
hydroxyl bearing polybutadiene, 833.0 grams of 3-isocyanatomethyl,
3,5,5 trimethylcyclohexyl isocyanate (7.5 eq.), 3953.0 grams of
paraffin oil and 4.0 grams of benzoyl chloride. The solution was
maintained at 75.degree.-85.degree. C. for 5 hours under nitrogen.
The free isocyanate content of the prepolymer was 2.56%.
b. Polymer Formation
25.0 grams (0.014 eq.) of the prepolymer was mixed with 16.8 grams
(0.014 eq.) of a hydroxyl bearing polybutadiene, 57.8 grams of a
paraffin oil and 0.4 grams of dibutyl in dilaurate.
TABLE C
__________________________________________________________________________
Prepolymers Equivalent Wt. Example Pre Polyol Isocyanate NCO/OH %
Free NCO Per NCO Group Viscosity (CPS) polymer Used in
__________________________________________________________________________
1 IPDI 3 2.56 1641 475 I, II, III, IV, XI 1 TDI 3 2.57 1635 330 V 3
TDI 2.47 10.8 389 20,000 VII, VIII, X, XII 3 Polymeric MDI 5.14 7.2
584 150 XIII 5 IPDI 3 4.85 866 4260 VI 6 IPDI 5 10.12 415.2 3850 IX
__________________________________________________________________________
TABLE D
__________________________________________________________________________
% Dielectric Volume Dissipation Coupler % % Paraffin % Polymer
Constant Resistivity Factor At Example No. No. Coupler/Wt.
Polymer/Wt. Oil/Wt. Extension At 1KH.sub.z * In OHM-cm* 1KH.sub.z *
__________________________________________________________________________
1 - Control None 0 29.3 70.3 240 -- -- -- (Incompatible Spews Oil)
II 1 15.0 8.0 76.3 953 2.55 2.45 .times. 10.sup.13 .009 III 2 20.0
15.0 64.8 432 2.73 4.18 .times. 10.sup.12 .011 IV 3 20.0 15.0 64.0
427 3.01 1.33 .times. 10.sup.11 .017 V 4 25.0 8.0 66.8 835 2.68
1.36 .times. 10.sup.13 .007 VI 5 20.0 15.0 64.0 427 2.74 6.10
.times. 10.sup.11 .017 VII 6 24.8 12.4 61.4 495 3.29 1.53 .times.
10.sup.13 .029 VIII 7 24.8 12.4 61.6 497 2.74 2.59 .times.0
.016up.10 IX 1 20.0 15.0 64.0 427 2.71 3.47 .times. 10.sup.12 .007
X 13 20.0 15.0 64.5 430 2.99 6.89 .times. 10.sup. .015 XI 14 20.0
15.0 64.5 430 3.42 3.44 .times. 10.sup.10 .025 XII 15 20.0 15.0
64.5 430 3.23 1.07 .times. 10.sup.11 .017 XIII
.[.4.]..Iadd.6.Iaddend. 30.0 35.0 35.0 100 3.0 2.43 .times.
10.sup.13 .015
__________________________________________________________________________
*Electrical measurements made at 25.degree. C.
The resulting clear solution within 4 hours turned opaque and
within 24 hours cured at room temperature to greyish-white, opaque
oil spewing mass containing 29.3% polymer which was incompatible
with the 70.3% mineral oil.
EXAMPLE II
a. Prepolymer Formation
Same prepolymer as in Example I.
b. Polymer Formation
6.4 grams (0.004 eq.) of the prepolymer was mixed with 4.8 grams
(0.004 eq.) of the hydroxyl bearing polybutadiene, 73.1 grams of
mineral oil. 15.0 grams of .[.2,2,4 trimethyl 1,3 pentanediol,
diisobutyrate.]. .Iadd.2,2,4 trimethyl 1,3 pentanediol
diisobutyrate .Iaddend.and 0.7 grams of dibutyl tin dilaurate. The
resulting solution cured over a 120 hour period to a clear, very
soft, dry, non-oil spewing mass which contained 8% polymer and
76.3% mineral oil. This represents a 953% extension of the polymer
by mineral oil.
EXAMPLE III
a. Prepolymer Formation
Same as prepolymer as in Example I.
b. Polymer Formation
16.3 grams (0.01 eq.) of prepolymer was mixed with 1.5 grams
(0.0045 eq.) of castor oil, 5.3 grams (0.0045 eq.) of a hydroxyl
bearing polybutadiene, 56.6 grams of mineral oil, 20.0 grams of
di-2-ethylhexyl sebacate, and 0.3 grams of dibutyl tin dilaurate.
The resulting solution cured over a 48 hour period at room
temperature to a clear, soft, dry, non-oil spewing mass containing
15% polymer and 64.8% mineral oil. This represents a 432% extension
of the polymer with mineral oil.
EXAMPLE IV
a. Prepolymer Formation
Same prepolymer as in Example I.
b. Polymer Formation
13.2 grams (0.0074 eq.) of prepolymer was mixed with 4.7 grams
(0.0037 eq.) of a hydroxyl bearing polybutadiene, 3.7 grams (0.0037
eq.) of a polypropylene glycol, 20.0 grams of acetyl tributyl
citrate, 57.4 grams of mineral oil and 1.0 grams of dibutyl tin
dilaurate, The resulting solution cured over a 48 hour period at
room .[.temrature.]. .Iadd.temperature .Iaddend.to a clear, soft,
dry, non-oil spewing mass containing 15% polymer and 64% mineral
oil. This represents a 426% extension of the polymer with paraffin
oil.
EXAMPLE V
a. Prepolymer Formation
A reactor vessel equipped as in Example I was charged with 52.2
grams (0.6 eq.) of toluene diisocyanate (80/20), 181.3 grams of
mineral oil, 120.9 grams of di-2-ethylhexyl adipate, and 250.0
grams (0.2 eq.) of a hydroxyl bearing polybutadiene, and 0.3 grams
of benzoyl chloride. The solution as heated under nitrogen for 4
hours at 75.degree.-80.degree. C. The resulting prepolymer had a
free isocyanate content of 2.57%.
b. Polymer Formation
6.3 grams of the prepolymer (0.039 eq.) was mixed with 4.8 grams
(.0039 eq.) of a hydroxyl bearing polybutadiene, 23.7 grams of di
(2-ethylhexyl) adipate, 65.0 grams of mineral oil and 0.2 grams of
dibutyl tin dilaurate. The solution cured at room temperature over
a 120 hour period to a clear, very soft, dry, non-oil spewing mass
containing 8% polymer and 66.8% mineral oil. This represents an
835% extension of the polymer by mineral oil.
EXAMPLE VI
a. Prepolymer Formation
A reactor equipped as in Example I was charged with 2487.0 grams
(1.8 eq.) of a triol (derived from the reaction of propylene oxide
and trimethylol propane) 600 grams of 3 isocyanatomethyl 3,5,5,
trimethylcyclohexyl isocyanate (5.4 eq.), 1.6 grams of
.[.benzoly.]. .Iadd.benzoyl .Iaddend.chloride, and 1.6 grams of
dibutyl tin dilaurate. The solution as heated at 80.degree. C. for
6 hours under nitrogen. The resulting prepolymer had a free
isocyanate content of 4.85%.
b. Polymer Formation
6.4 grams (.0074 eq.) of the prepolymer, 8.6 grams of a hydroxyl
bearing polybutadiene (.0048 eq.), 20.0 grams of diisodecyl
phthalate, 64.0 grams of mineral oil and 1.0 grams of dibutyl tin
dilaurate were mixed. The resulting solution cured at room
temperature over a 48 hour period to a clear, soft, dry, non-oil
spewing mass containing 15% polymer and 64% mineral oil. This
represents a 427% mineral oil extension of the polymer.
EXAMPLE VII
a. Prepolymer Formation
A reaction vessel equipped as in Example I as well as with a
dropping funnel, was charged with 386.0 grams (4.44 eq.) of toluene
diisocyanate 614.0 grams of castor oil (1.8 eq.) was added, over a
2 hour period, through the dropping funnel at 70.degree.-80.degree.
C. After the addition was complete, the reactor was held at
75.degree. C. for 1 hour. The free isocyanate content of the
prepolymer was 10.8%.
b. Polymer Formation
3 grams (.0076 eq.) of the prepolymer was mixed with 9.4 grams
(.0076 eq.) of a hydroxy bearing polybutadiene, 24.8 grams of
dioctyl adipate, 61.4 grams of paraffin oil and 1.4 grams of
dibutyl tin dilaurate. The resulting solution cured at room
temperature over a 48 hour period to a soft, clear, dry, non-oil
spewing mass which contained 12.4% polymer and 71.4% mineral oil.
This represents a 495% extension of the polyurethane with mineral
oil.
EXAMPLE VIII
a. Prepolymer Formation
Same prepolymer as in Example VII.
b. Polymer Formation
2.4 grams (.0061 eq.) of the prepolymer was mixed with 10.0 grams
of a hydroxyl bearing copolymer of styrenebutadiene (.0061 eq.),
24.8 grams of tributyl phosphate, .[.61.4.]. .Iadd.61.6
.Iaddend.grams of mineral oil and 1.2 grams of dibutyl tin
dilaurate. The resulting solution cured at room temperature over a
48 hour period to a soft, clear, dry, non-oil spewing mass
containing 12.4% polymer and 61.6% mineral oil. This represents a
497% mineral oil extension of the polyurethane.
EXAMPLE IX
a. Prepolymer Formation
A reactor fitted with agitator, thermometer nitrogen inlet and
reflux condenser was charged with 1001.8 grams (1 eq.) of a
.[.polytetramethylene glycol.]. .Iadd.polytetramethylene ether
glycol .Iaddend.and 555.5 grams (5 eq.) of
.[.3-isocyanatomenthyl,.]. .Iadd.3-isocyanatomethyl, .Iaddend.3,5,5
trimethylcyclohexyl isocyanate. The solution was maintained at
80.degree. C. for 2 hours. The resulting prepolymer had a free
isocyanate content of 10.12%.
b. Polymer Formation
3.7 grams (.0089 eq.) of the prepolymer was mixed with 11.3 grams
(.0089 eq.) of a hydroxyl bearing polybutadiene (OH functionality
2.3-2.4) 64.0 grams of a mineral oil, 20.0 grams of 2,2,4
trimethyl--1,3 pentanediol diisobutyrate and 1.0 grams of dibutyl
tin dilaurate. The resulting solution cured after 11/2 hours at
100.degree. C. to a clear, dry, non-oil spewing mass containing 15%
polymer and 64% mineral oil. This represents a 427% mineral oil
extension of the polymer.
EXAMPLE X
a. Prepolymer Formation
Same prepolymer as in Example VII.
b. Polymer Formation
3.5 grams (0.009 eq.) of the prepolymer was mixed with 11.5 grams
(.009) of hydroxy bearing polybutadiene, 20.0 grams of isobutyl
acetate, 64.5 grams of a mineral oil and 0.5 grams of dibutyl tin
dilaurate. The resulting solution cured over a 24 hour period at
room temperature .[.of.]. .Iadd.to .Iaddend.a soft, clear, dry,
non-oil spewing mass which contained 15% polymer and 64.5% mineral
oil. This was a 430% mineral oil extension of the polymer.
EXAMPLE XI
a. Prepolymer Formation
Same Prepolymer as in Example I.
b. Polymer Formation
12.5 grams of prepolymer (0.0077 eq.) was mixed with 8.8 grams
(0.0077 eq.) of a hydroxyl bearing polybutadiene, 20.0 grams of
methyl-ethyl ketone, 58.2 grams of mineral oil and 0.5 grams of
dibutyl tin dilaurate. The resulting solution cured at room
temperature over a 48 hour period to a soft, dry, non-oil spewing
mass containing 15% polymer and 64.5 percent mineral oil. This
represents a 430% extension of the polymer by mineral oil.
EXAMPLE XII
a. Prepolymer Formation
Same prepolymer as in Example VII.
b. Polymer Formation
3.5 grams (.009 eq.) of prepolymer was mixed with 11.5 grams (.009
eq.) of a hydroxyl bearing polybutadiene, 20.0 grams of
methyl-n-butyl ketone, 64.5 grams of mineral oil and 0.5 grams of
dibutyl tin dilaurate. The resulting solution cured at room
temperature over a 24 hour period .[.of.]. .Iadd.to .Iaddend.a
clear, soft, dry, non-oil spewing mass which contained 15% polymer
and 64.5% mineral oil. This was a 430% mineral oil extension of the
polymer.
EXAMPLE XIII
a. Prepolymer Formation
A reactor vessel equipped as in Example I was charged with 145
grams (0.42 eq.) of castor oil, 286 grams polymeric MDI (2.16 eq.)
and 569 grams dioctyl adipate (DOA) the solution was heated under
nitrogen for 2 hours at 60.degree. C. The resulting prepolymer had
a free isocyanate content of 7.2%.
b. Polymer Formation
17.0 grams of the prepolymer (0.03 eq) were mixed with 26.2 grams
(0.021 eq) of a hydroxyl bearing polybutadiene, 1.4 grams castor
oil (0.004 eq) 35 grams of mineral oil, 20.1 grams of DOA and 0.3
grams dibutyl tin dilaurate. The solution cured at room temperature
over a 24 hour period to a clear, firm, dry, non-oil spewing
elastomeric material containing 35 percent polymer and 35 percent
mineral oil. This represents a 100 percent exension of the polymer
by mineral oil.
In the preceding examples the hydroxyl terminated liquid
homopolymer of polybutadiene employed is available from the
Altantic-Richfield Co. under the trade name POLY-BD R-45HT. Its
typical properties are:
______________________________________ Polybutadiene isomer content
Viscosity at 75.degree. F. - 80 poise Trans 1,4 - 60% Moisture
weight percent - 0.05 Cis 1,4 - 20% Iodine No. 398 Vinyl 1,2 - 20%
Hydroxyl content - 0.85 Meg/GM
______________________________________
The mineral oil used in the examples is available from Pennrico
Inc., Butler, Pennsylvania as "PENETECK", a highly paraffinic white
oil.
The materials produced in Examples I-XIII had an initial (low)
viscosity on the order of about 0.1 poises. However, within about 1
to 120 hours the material cured in situ at temperatures from about
15.degree. C. to about 100.degree. C. to a gel-like (high)
viscosity on the order of between 1,000 and 100,000 .[.poises..].
.Iadd.centipoise. .Iaddend.The mineral oil was completely
compatible with the prepolymer and polyol in all of Examples
II-XIII. In each case the mineral oil did not interfere with the
reaction of the prepolymer and polyol constituents to form a
polyurethane compound which cured to a gel. In each instance the
mineral extender oil did not exude or spew from the cured urethane
system.
The elastomeric rehabilitation materials of this invention are
ideally suited for use in reclaiming waterlogged electrical
apparatus such as, for example, plastic insulated conductors of the
type employed in multi-pair telephone cables. The method of
employing these mineral oil extended urethanes in rehabilitating
such an apparatus will now be illustrated with reference to FIG.
1.
In the cable illustrated in FIG. 1, a plurality of wire conductors
1 are disposed within the central core 2 of the cable. Each wire is
surrounded by an insulating material, generally a polyolefin
plastic. The plurality of insulated wires are tightly enclosed
within a spiral wound sheath 3, usually a polyethylene
terephthalate sheet material. Surrounding the sheath are two
protective shields 4, made of a flexible metal sheeting such as
aluminum. The shields are separated from one another by a
continuous layer 5 of a suitable insulating material. Finally, an
outer jacket 6 of a protective plastic such as polyethylene, covers
the outermost aluminum layer and serves to protect the cable.
Aqueous contaminants generally find their way into the cable
through pinholes and stress cracks that develop around fittings and
cable connectors, ultimately lodging in the interior free spaces of
central core 2. After a particular aqueous contaminant, for example
water, has been present for some time in the core, the electrical
properties of the cable can be deleteriously effected as previously
described. At this point, the rehabilitation products and processes
of this invention may be employed to restore the cable to
substantially its original operating condition.
The rehabilitation operation is carried out on location by first
admixing approximately equal .[.amount.]. .Iadd.amounts .Iaddend.of
the prepolymer and polyol ingredients which are most advantageously
prepared in advance. A small portion of the cable outer protective
layers including jacket 6, aluminum protective shields 4 and sheath
3 are then removed and a nipple (not shown) installed in the
opening thus formed, using techniques that are well-known in the
trade. This operation can be carried out from above, or below, and
without removing the cable from its resting place. The mineral oil
extended polyurethane elastomer having just been formed has a
relatively low viscosity and is easily introduced into the core of
the cable through a hose (not shown) connected to the nipple. After
the rehabilitation material has been injected into the cable, the
delivery hose is withdrawn from the nipple and the hole in the
nipple is sealed with a plug (not shown). The injection operation
will have driven the low viscosity mineral extended urethane out
through the interior-free spaces of the cable. The rehabilitation
agent will displace the water penetrants in the interior free
spaces (e.g. between the individual wires and the outer
polyethylene terephthalate sheath).
In the practice of the invention, the viscosity of the
rehabilitation material at from about 15.degree. C. to about
50.degree. C. at the time of injection should be within the range
of about 10 to 100 centipoises. Within several hours after
injection into an insulated electrical device, the rehabilitation
agent cures to form an oil extended polymer system having a
gel-like consistency and a viscosity on the order of about 1000
.[.poises..]. .Iadd.centipoise. .Iaddend.The clear gel is
physically and chemically stable and does not lose mineral oil by
exudation or spewing. The hydrophobic nature of the cured oil
extended elatomer system also serves to seal the cable against
subsequent penetration of water or other fluid materials.
Furthermore, the gelled system has good insulating properties due
to its relatively low dielectric constant and high volume
resistivity.
The elastomer material retains the mineral oil and no exudation was
evident in any of the formulations made in Examples II-.[.XII.].
.Iadd.XIII .Iaddend.after standing for several weeks at ambient
(room) temperature. Moreover, the mineral oil extended urethanes
were found to be compatible with the polycarbonate plastic
connectors used in the interconnection of insulated electrical
devices. After several weeks exposure to the rehabilitation
compounds of this invention, the polycarbonate connectors on
plastic insulated conductor cable were completely unaffected and
did not exhibit any signs of chemical attack. The rehabilitation
compounds were also compatible with polyolefin insulating materials
used in the cable manufacture and no stress cracking was observed
after several weeks exposure.
The oil extended rehabilitation material was non-solvating in
nature and did not attack polyethylene terephthalate or the other
polymer materials employed in the cable construction. The material
was also characterized by easy handling in view of its low
volatility (vapor pressure) and inoffensive aroma. No toxicity or
adverse side effects have been noted by those handling the
rehabilitation materials of this invention, thus setting them apart
from the relatively toxic products previously employed in
reclamation techniques.
The treated cable showed only a minor weight gain, which is
probably attributable to the low density of the cured
rehabilitation material. It has also been noted that the present
system results in only a minimal amount of air being entrapped in
the cured system after injection into an insulated electrical
device. This can be related to the low viscosity and density of the
initial ingredients which may be pumped into the cable without
causing excessive turbulence.
In addition to the reclamation of insulated electrical apparatus,
the mineral oil polymer system can also be used as a waterproofing
membrane in the construction field, cast into a resilient flooring
compound (using higher level of polymer as represented by Example
XIII); used as a liquid casting system for a variety of potting and
encapsulation applications as well as a solid lubricant to replace
grease in certain situations.
While this invention has been described and illustrated by the
examples shown, it is not intended to be strictly limited thereto,
and other variations and modifications may be employed within the
scope of the following claims.
* * * * *