Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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219 416-US-01 PATE~lT
A COAL TAR CONTAINING FOAMING URETHANE
COMPOSITION A~D A METHOD FOR REPAIRING
DEFECTS IN STRUCTURAL COMPONENTS
Field of the Invention
The invention relates to a hydrophobic-foaming
polyurethane composition that can be packaged in sepa-
rate parts, namel~ a hydrophobic polyol part and an
isocyanate part. The parts can be combined at an
effective stoichiometric ratio to form a hard, rigid
solid foam mass. The invention also relates to the use
of the polyurethane composition in the repair of
surface defects in structural members such as spike
holes left after spike removal from railroad ties during
road bed maintenance or repair.
Back~round of the Invention
~ In view of current economic conditions, substantial
; attention has been given to the recycle of used struc-
tural components in new construction and in general
maintenance. The use of used structural components can
~o be an economic benefit since the cost of new materials
is often substantially greater than the cost of obtain--
ing the used material. Such recycle can be effective if
the recycled material is structurally sound. Struc-
turally sound recycled structural com~onents can often
be obtained if the components are repaired.
In the instance that the structural components ar~
formed from materials such as wood, plastic, concrete
and others, surface defects must be repaired before the
component can be reused. Such defects can appear as ~
cuts, gaps, deep holes, cracks, etc. Such defects can
substantially reduce the value of the recycled component
in new construction since the defect can result in a
fastener -having an imperfect bond to a structural
member, the defect can be aesthetically unpleasing or
the defect can reduce the structural strength of the
member.
Materials used to repair surface defects in struc-
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-- 2 --tural members should have certain characteristics. The
material should be easily applied and should form high
strength bonds to structural members made of varying
materials. The repair materials should be useable in
many environments including environments having extremes
of heat and cold and having the presence of substantial
quantities of environmental water.
One particularly important end use for such repair
compositions is in the recycle or reuse of railroad
ties. Typically in the maintenance of the railroad
right of way the railroad rails, along with tie plates
and spikes, are removed from railroad ties which remain
in the roadbed. If a new rail is to be spiked to the
old tie, it is critical that the railroad tie spike
holes be repaired prior to laying the new rail. The
presence of spike holes in an old tie can cause problems
since if a spike is driven into a portion of the tie
near an old spike hole, the driving force of the spike
can displace the spike from its intended location into
an old hole, displacing the rail, tie plate and spike.
In the instance that the spike is driven into incorrect
location substantial economic loss can result in
repairing the misaligned rail. If a misaligned rail is
not repaired, the defect can cause derailment or other
problems. Further, the spike holes can be the-source of
structural weakness in the tie.
Mechanical spike hole repair means have been
suggested in the art in for example, Moses, U.S. Patent
No. 3,191,864 which teaches a mechanical spike hole
insert used by first boring out an old spike hole,
installing an insert and driving a new spike into the
insert; and Newman, U.S. Patent No. 3,716,608, which
teaches metallic inserts that can be placed in bored out
spike holes with a filling of a synthetic resin into
which the spikes can be driven. In another area of
repair, Tessenski, U.S. Patent Nos. 4,070,201 and
4,152,185, teach a railroad tie spike hole plugging
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material and method using a substantial uniorm mixture
of a granular abrasive material and a granular plastic
material which is poured into the hole left after spike
removal. The driving force of a spike into the abrasive
material generates heat which plasticizes the material
resulting in a firm bond of the spike to the material.
Mechanical and resin-based hole filling methods tend to
be time consuming, expensive and adapted to manual not
automatic application or installation.
Rhodes et al, U.S. Patent No. 4,295,259, teaches a
method of reusing wooden railroad ties in which spike
holes are filled with a high-density, polyurethane foam
composition. We have found that the use of polyurethane
foam in filling spike holes in used railroad ties can
present significant problems. The polyurethane foam
compositions do not appear to adhere to a spike hole
with sufficient adhesion to prevent the accidental
removal of the foam repair mass during the repair and
subsequent mechanical rail installation. Further, the
urethane foams of the prior art tend to foam uncontrol-
lably in the presence of substantial environmental'
moisture. Since, the moisture tends to accelerate the
foaming properties of the urethane composition, the
presence of water can cause the too rapid formation of a
2~ foam mass of low strength and density and can result
in the formation of an incomplete or unreliable repair.
Accordingly, a substantial need exists in the art
for compositions that can be used to repair surface
,defects on structural components such a railroad ties
which provide a repair mass having strong adhesion to
the substrate structural member, can be used in the
presence of substantial quantities of environmental
water and can be used in automatic application equip-
ment.
Brief Discussion_of the Invention
We have found a two-package ,hydrophobic urethane
foaming composition that can be used to repair surface
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defects in structural members by forming a rigid repair
mass that bonds strongly to the structural member.
- The first package comprises a polyol made hydrophobic by
the presence of an effective amount of a coal tar or
coal tar pitch composition. The second package com-
prises an isocyanate compound having at least two -NCO
groups. The two parts, when mixed at an effective
stoichiometric mixing ratio to form a rigid mass, can be
applied both manually and with automatic injection into
surface defects in structural members, can repel and
avoid an inappropriate reaction with water present
at the application site and can rapidly form a hard,
structurally sound, firmly bonded repair mass having
strong adhesion to the substrate. The coal tar, in
combination with the other components of the composi-
tion, appears to enhance many properties of the compo-
sition. The hydrophobicity of the injected urethane
foam, enables the foam to repel any environmental water
that is present in the application site and prevents the
water from reacting with the mixed components. Further,
the hydrophobic nature of the composition prevents the
environmental water combining with the resulting foam to
any significant extent. Since the hydrophobic nature of
the composition repels water, the presence of enYiron-
mental water in the repair site cannot alter the reac-
tion rate or the combination of the reaction mixture.
Further~ the combination of the coal tar or coal tar
pitch composition with the other components appears to
result in an increased bond strength as a result of the -
interaction of the components and the surface defect.
Coal tars have been combined in urethane composi-
tion in the past. However, in the prior art composi-
tions the- coal tar or pitch composition is used in
preparing an isocyanate prepolymer in which a di-, tri-
or polyisocyanate compound is reacted with the coal tarto form an isocyanate prepolymer. As a result, in the
prepolymer, the coal tar is effectively one moiety
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of the isocyanate compound. The coal tar-prepolymer
composition can then be reacted with the polyols
resulting in a urethane composition.
We have found that in the compositions of the
invention, the coal tar pitch is most useful when
included in the polyol and we believe that in such
combination, the coal tar does not appear to participate
in a polyisocyanate-polyol reaction and does not form an
isocyanate prepolymer. The production prepolymers from
coal tar and polyisocyanate compounds are disclosed in
Schearing, U.K. Patent No. 1,323,884; Carlton et al, U.S.
Patent No. 3,182,032; Elkin, U.S. Patent No. 3,412,050;
and Mihelic, U.S. Patent No. 3,749,688.
Summary of the Invention
Thus in one embodiment the present invention
provides a method of repair of a structural member having
a surface defect, with a foaming hydrophobic urethane
composition that can repair the defect in the presence of
environmental water and can form a strong bond, which
comprises locating a surface defect in a structural
member; obtaining a hydrophobic two package polyurethane
composition comprising: in a first package, a hydrophobic
polyol having about 99.5 to 55 parts of a polyol
composition and about 0.1 to 45 parts of a coal tar, an
effective foaming amount of water and an effective amount
of a polyurethane catalyst; in a second package, an
isocyanate composition comprising an isocyanate compound
having at least two -NCO groups; and blending the first
and second packages at a -OH to -NCO mole ratio of about
0.1 to 10:1 to form a blended hydrophobic polyurethane
composition; and applying the blended hydrophobic
polyurethane composition to the surface defect.
In another embodiment the present invention provides
a two package polyurethane composition that can be
combined and applied to a structural member to form a
rigid high-density foam that is hydrophobic which
consists essentially of: in a first package a hydrophobic
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polyol composition comprising about 99.9 to 55 parts of a
polyol composition, about 0.1 to 45 parts of coal tar, an
effective foaming amount of water, and a polyurethane
catalyst; and in a second package an isocyanate
composition comprising an isocyanate compound having at
least two -NCO groups; wherein the first package and the
second package can be combined at a -OH to -NCO mole
ratio of about 1.0 to 10:1.
Detailed Discussion_of the Invention
The compositions of the lnvention can be made by
combining a first package containing a hydrophobic coal
tar containing polyol composition with a second package
containing a polyisocyanate composition.
Coal Tar
Coal tar or coal tar pitch, that can be used in the
hydrophobic polyol package, is a by-product of the
manufacture of coke from coal. In the manufacture of
coke, during the destructive distillation of coal, coal
tar results from the high-temperature heat volatilization
of organic constituents of coal and a solid coke residue
comprising primarily elemental carbon remains. During
the destructive distillation, compounds volatile at
temperatures which range up to about 800C. are driven
off. Coal tar or coal tar pitch is the heavy fraction
having the highest boiling points of the volatile
compositions derived from coal. Coal tar pitch is
typically a black solid comprising a variety of
polynuclear aromatic compounds. The compounds can have
from about 1 to 30-40 aromatic rings. Coal tar pitch
tends to have an average molecular weiyht of about 300 to
1000 depending on the production facility and the source
of the coal. The coal tar is an item of commerce and can
be obtained from U.S. Steel Company, ~llied Chemical
Company, other steel manufacturers or coke producers.
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Polyol
The term polyol includes many organic compounds
having two or more hydroxyl groups on an essentially
organic substrate. The term polyol includes diols,
triols, tetraols, etc. including such compounds such
as ethylene glycol, polyethylene glycol, polypropylene
glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-
~utylene glycol, 1,4-cyclohexane diol, saccharide
compounds,polysaccharide compounds,polyalkalene ether
glycols, etc. The polyols can be used in both the
hydrophobic polyol part and the polyisocyanate part.
The preferred polyol for use in the iscoyanate
composition is a polyalkylene glycol which is a
composition having at least two hydroxyl groups and at
least one terminal hydroxyl group. These compounds are
ordinarily derived from the polymerization of cyclic
ethers such as an alkylene oxide compound or from
condensation of glycols, and are sometimes known as
alkylene glycols, polyalkylene oxide glycols,
polyglycols or polyalkylene ether glycols. They may
be represented by the formula HO(RO)nH, in which R is
an alkylene radical and n i5 an inte~er greater than
1. In the polyols useful in the invention, n is
sufficiently large to result in a polyalkylene glycol
having a molecular weight of at leas~ 750. Not all the
alkylene groups in the polymer chain need be the same.
Polyalkylene glycols formed by the polymerization of
a mixture of different alkylene oxides or glycols may
be used. Polyalkylene glycol may bP derived from a
cyclic ether such as dioxolane, which results in a
product having the formula HO(CH20C2H40)nH. Examples of
the compounds which contain a mixture of alkylene
groups and which are useful in the preparation of many
compositions are those polyethers described in U.S.
Patent No.
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2,492,955~ The alkylene radicals may be straight-chain
or may have branched chains as in the compound known
as polypropylene ether glycol, having the formula:
HO-(CH2-lH-O)nH
CH3
Wherein n i5 an integer of 10 to 30,000. Useful
polyalkylene glycols are typically viscous liquids or
waxy solids. Those most useful in the process and
products of this invention have an average molecular
weight of about 750-10,000. The molecular weight of
the most preferred polyalkylene ether glycols r~ng~
from about 750 to 3,500.
A preferred class of polyols for use in the
hydrophobic coal tar containing polyol part comprises
a polyol reaction product of a mono-, di- or poly-
saccharide compound with an alkanolamine compound.
Saccharide compounds that can be used in the polyol
composition include, glucose, fructose, galatose, etc.;
disaccharides that can be used include sucrose,
lactose, maltose, etc.; polysaccharides that can be
used include various starches and other well-known
compositions. A most preferred class of polyols
comprises mixtures of (1) a polyol reaction product of
a saccharide compound and an alkanolamine compound and
(2) a polyalkylene glycol. Alkanolamine compounds that
can be used in the hydrophobic polyol part compounds
have the formula:
[ ~IO ( CH2 ) n ] mNH3-m
wherein n and m are independently an integer of 1 to
3. The polyols are made by reacting the saccharide
compound with the alkanolamine compound at
approximately equimolar proportions resulting in a
composition that reacts rapidly with the isocyanate.
These compounds are commercially available as the
"VORANOL 800~" polyether polyols made by Dow Chemical
Company, and the Poly G~ polyols made by Olin Chemical
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Company (70-660; 71-530; 71-357). The polyol may also
comprise ricinoleic acid triglyceride, and preferably,
the polyol comprises 0.1 to 1 part of a ricinoleic acid
triglyceride per each part of the reaction product.
Any of the wide variety of organic polyisocyanate
compositions may be employed in the isocyanate part.
Aromatic, aliphatic andcycloaliphatic polyisocyanates,
polyisocyanate prepolymers and combinations thereof may
be used. Representative compounds include 2,4-toluene
diisocyanate (TDI), diphenyl methane diisocyanate
(MDI), m-phenylene diisocyanate, 4-chloro-1,3-phenylene
diisocyanate, 4,4'-biphenylene diisocyanate, 1,5-
naphthylene diisocyanate, 1,4-tetramethylene
diisocyanate, 6-hexamethylene diisocyanate, 1,10-
lS decamethylene diisocyanate, 1,4-cyclohexylene
diisocyanate, 4,4'-methylene-bis tcyclohexyl
isocyanate) and others. Aromatic diisocyanates, those
which have at least two iscoyanate groups directly
attached to an aromatic ring are preferred. Generally,
aromatic isocyanates react in the urethane reaction
more rapidly with polyols than the aliphatic
isocyanates. NDI, diphenylmethane diisocyanate, is the
preferred polyisocyanate for reasons for rapid reaction
and economy. The isocyanate compounds can contain
other substituents which do not substantially alter the
reactive nature of the isocyanate groups.
Catalyst
The rate of reaction of th~ composition of this
invention after mixing can be increased or enhanc~d as
desired by the incorporation of effective amounts of
catalysts to promote the reaction of the isocyanato
groups with the polyol. Typically catalysts include
organic amine compounds and organo tin compounds.
Specific examples of useful c~atalysts include dibutyl-
tindilaurate, stannous octoate, tertiary aliphatic and
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tertiary alicyclic amines including triethylamine,
triethanolamine, tri-n-butylamine, triethylenediamine,
alkylmorpholene, etc. Complex mixtures of such
catalysts in modified form may also be employed.
Plasticizers can be used in the polyurethane
compositions of this invention to improve viscosity of
the parts and to improve hardness, flexural modulus,
and cure time. Often a single plasticizer will be
sufficient to impart the desired properties to the
uncured packages and the cured foamed product. In
certain instances two or more plasticizers can
cooperate and can be used advantageously. Well-known
plasticizers that can be used in the compositions of
the invention include phthalate esters, alkyl
phosphates, polyphenyls, aromatic oils, chlorinated
waxes or paraffins, adipate esters, synthetic rubber
polymers, natural oils, rosin and rosin derivatives,
and polysulfide rubber. Typically the amount of
plasticizer will range from 0.5 to 10 wt % of solids.
Preferredplasticizers include polyFhenylplasticisizer
and partially hydrogenated di- or triphenyl
plasticizers.
Fillers, water, extenders, thickeners, additional
catalysts, pigments and the like can be included in the
polyurethane composition. Neutral fillers are
ordinarily preferred to a~oid gassing during or
decomposition during storage. Acidic and basic fillers
should be avoided. Water may be present at about 0.01
to 1 part of water per each part of the polyol.
In somewhat greater detail, ~he two-package
polyurethane composition can be made by a process
divided into two stages which can be performed in any
order. The first s~age comprises formation of a
hydrophobic polyol package and the second stage
comprises the formation of the isocyanate package. The
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polyol package and the polyisocyanate package are
individually prepared using commonly available blending
and mixing techniques for isocyanate compositions. The
two-package composition of the package composition of
the invention is most effectively used by mixing and
applying the composition using automatic injection
equipment that blends the packages at an appropriate
ratio. Such apparatus is commonly available to the
industry and can be adapted to the repair of a variety
of structural memb~rs.
Typically the hydrophobic polyol composition
contains an effective amount of a polyol to participate
in the urethane'reaction and an effective hydrophobic
amount of a coal tar composition comprising about 99.5
to 55 parts of polyol and 0.1 to 45 parts of coal tar
preferably the hydrophobic polyol contains 90 tc 80
parts of polyol and 10 to 20 parts of coal tar. Most
prefer~bly for reasons of economy, bond strength and
hydrophobic properties, the hydrophobic polyol contains
about 82.5 to 87.5 parts of polyol and from about 12.5
to 17.5 parts of coal tar.
The isocyanate composition can contain from about
100 to 50 parts of the isocyanate compound and from
about 0.1 to 50 parts of a polyol mixture thereof. The
polyol mixture can contain from 1 to 10 additional
polyol compositions and each polyol composition can be
present at a concentration of from about 0,1 to 50
parts of the isocyanate package.
The packages are blended and applied a~ a ratio of
-OH groups in the hydrophobic polyol package to the -
NCO groups in th~ polyisocyanate package sufficient to
result in a rigid, strongly bonding repair mass.
Typically the packages are blended at -NCO to -OH ratio
of about 0.1 to 10 moles of -NCO per mole -OH groups.
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Preferably the ratio is more nearly stoichiometric and
is about O.25 to 5 moles of NCO per mole of hydroxyl
and most preferably for reasons of rapid reaction and
bond strength, the ratio is about 0.9 to 1.25 moles of
-NCO per mole of -OH.
In the repair of a railroad tie, the composition
of the tie, the composition of the invention is
preferably applied to spike holes using an automatic
mixing and injection machine that is part of a track
repair machine that in one procedure removes the spike,
and spike plate, lifts or replaces the railroad rail,
repairs spike holes using the polyisocyanate
composition of the invention, replaces the spike plate
and rail and respikes the assembly together.
Sufficient time can be given to insure that the foaming
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isocyanate composition is fully set prior to reassembly.
The following examples provide a further under-
standing o the compositions of the invention and
include a best mode.
Rxample I
Into an industrial Cowles dissolver was placed 35.0
parts of a polyol reaction product between sucrose and
diethanolamine having an average molecular weight of
about 720, a hydroxyl number of about 350 ' 10, and
approximately 4.5 hydroxyl groups per mole (POLY-G
71-357, OLIN CHEM CO.) ; 35.0 parts of castor oil,
a triglyceride of 12-hydroxy-oleic acid (ricinoleic
acid); and 14.5 parts of another polyether polyol
reaction product of sucrose and diethanolamine having a
hydroxyl number of 800 (VORANOL 800, Dow Chemical
Company). The Cowles dissolver was operated at low
speed until the mixture was homogenous. Into the
mixture was added 0.5 parts of a tertiary aliphatic
amine catalyst ~Dabco 33-LV), 0.2 parts of tri-n-
butyltin mercaptide catalyst (Catalyst 120-M&T Chemical
Company) and 2.0 parts of a silicone defoamer (Dow-
Corning DC-193 Silicone surfactan~)O The mixture was
~heared until uniform and to the agitated mixture was
added 12.6 parts of coal tar (CP-524 Allied Chemical
Company) and 0.2 parts of water. The resulting mixture
was blended until completely homogenous. The resulting
hydrophobic polyol composition had an initial viscosity
of 1800 cP, Brvokfield vi~cosity ~3 spindle @ 20
rpm and 77 F.
The isocyanate composition was made by adding to a
Cowles dispersing ribbon mixer at room temperature about
16.2 parts of a polypropylene glycol polyol having an
average molecular weight of about 1000 and an average
hydroxyl number of about I68 (Poly G 30-168 Olin
Chemicals), 79 parts of diphenyl methane diisocyanate
~-NCO functionality 2.2, PAPI 94-Upjohn Company) and 4.8
parts of a quadraphenyl plasticizer (MXP-2020 Monsanto
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Chemical Company) under conditions of mixing and under
vacuum.
The polyol composition was mixed with the isocy-
anate composition at a 1 to 1 volume ratio under auto-
mated mechanical mixing7 After mixing, the resultingrigid foam had a density of 20.0 pounds per cubic foot.
The cream time, the time at which the first bubble
formation and the first sharp exo~herm was noted, was
about 15 seconds after mixing. The rise time, ~he total
time of volume increase, was 20 to 40 seconds. The foam
was tack free after about 45 seconds r
Example II
Example I was repeated except that in the hydro-
phobic polyol part a tertiary ~mine catalyst ~Fomrez
UL-l Witco Company) was substituted for the tri-n-
butyltin mercaptan catalyst and in the isocyanate
package an diphenyl methane diisocyanate -NCO function-
ality 2.7, PAPI-27 Upjohn Company) was substituted for
the PAPI-94. The hydrophobic polyol part and the
isocyanate part were blended at a 1 to 1 ratio by
volume. The resulting product had a cream time of 15-20
seconds, a rise time of 20-40 seconds, a tack free time
of 40-50 seconds and a foam density of about 15.5 pounds
per cubic foot.
The specification example and data presented above
provide a basis for understanding the invention.
However, since many ebodiments and variations can be
made within the invention without departing from the
spirit and scope of the invention, the invention resides
in the claims hereinafter appended.
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