Note: Descriptions are shown in the official language in which they were submitted.
WO 94/16027 , ~ ~ ~ PCTlUS93/04679
LIQUID ADHESIVE THERMOSET COMPOSITION
Field of the Invention
The invention generally relates to liquid,
film-forming, thermosetting adhesive compositions. More
specifically, the invention relates to adhesive
compositions that can form an adhesive film which cures
to a rigid bond.
Background of the Invention
Thermoset compositions are well-known within the
coating, adhesive, composite, and plastics industry.
Recently, powdered thermosets have become desirable due
to their long-term storage stability and ease of
handling. However, difficult problems arise when
applying powdered compositions in various applications.
For instance, in applications where the powder is
applied directly to a substrate, the substrate must be
held stationary until the powdered thermoset is cured.
Exposure of the powder-laden substrate to movement,
vibration, air flow or other environmental stresses may
result in the removal of the powdered.thermoset from the
substrate. Moreover, simply applying the powdered
thermoset from a solvent such as water or ethanol often
does not provide the means necessary to maintain the
powder on the intended surface as these solvents may
evaporate leaving the powdered thermoset free to fall
from the intended surface.
Certain solvents may not allow for the long term
storage of the adhesive composition in the liquid state.
Also, once the thermoset composition is applied onto or
into a carrier to form a preimpregnated composite or
deposited film, the system may require refrigeration to
ensure that the composite will remain reactive and
capable of curing once applied to the desired
application. In fact, even when refrigerated the shelf
life of certain composite materials may often be
measured in terms of days or weeks instead of months.
Furthermore, certain methods of applying powders
such as electrostatic applications are limited by
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factors such as the particle size of the powdered thermoset
composition or the geometry of the area of application. These
methods may not allow for the most uniform application of
particles into narrow or tight areas due to electrical forces
created by the surfaces of application. Overall, present
methods of applying powdered thermoset compositions do not
accurately control particle concentration over the surface of
application, or the size of the particle domaine for each
individual particle. As a result, present compositions and
processes of application may result in a bond having variable
uniformity and strength.
Accordingly, there is a need for a powdered thermoset
composition which has extended stability at room temperature
and preferably avoids stability and toxicity problems as well
as providing for a method of application which results in a
bond having a higher degree of uniform strength than those
found in the prior art.
Summary of the Invention
The present invention comprises a liquid adhesive
dispersion which can cure to a thermoset bond, comprising an
effective amount of film forming agent; and comprising in
solid phase: an effective amount of a powdered thermosetting
resin or composition having a particle size of 1 to 5 microns;
and in a liquid phase: a liquid vehicle; wherein said
dispersion remains storage stable at ambient temperatures, and
after application, said dispersion forms a physically stable
intermediate film.
Preferably the thermosetting resin or composition is
selected from the group of polymeric material consisting of
an epoxy, a polyurethane, a polyester, a bis-maleimide, an
acrylic, mixtures thereof and hybrids thereof.
Preferably the film forming agent comprises a
theromplastic polymer composed of one or more monomers
selected from the group consisting of vinyl acetate, ethylene,
CA 02152776 1999-08-19
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acrylic acid, methacrylic acid, crotonic acid, itaconic acid,
esters of acrylic acid, esters of methacrylic acid, stylene,
butadiene, vinyl chloride, vinyllidene chloride, isoprene,
chlorprene, polyvinyl alcohol, and malefic anhydride.
Preferably the film-forming agent comprises a polymer
selected from the group consisting of cellulose polymers,
ether cellulose polymers, derivatized cellulosic and ether
cellulosic polymers, starch, starch grafted copolymers, guar
gum, karaya gum, and dextrine.
Preferably the dispersion comprises a dispersant selected
from the group consisting of silicates, polyphosphate salts,
colloidal proteins, surfactants, cellulosic polymers, starch
compositions and fatty acid soups.
A further aspect of the present invention is a method of
using this liquid adhesive dispersion comprising the steps of
applying the liquid adhesive dispersion composition to a
substrate and forming a physically stable intermediate film
capable of curing to a thermoset bond. Optionally the method
may include forming a workpiece by
placing a second substrate onto said intermediate film and
curing tha thermosetting resin or composition contained within
said intermediate film to create an adhesive bond.
The method may additionally comprising the steps of:-
placing a plurality of said thermosetting film laden carriers
together in series; and heat curing said thermosetting f~.lm
laden carrier to produce a composite laminate structure.
An additional aspect of the invention. is an article of
manufacture or a workpiece comprising a substrate coated with
a physically stable adhesive dispersion which can cure to a
thermoset bond, the liquid adhesive disper3ion comprising an
effective amount of a film farming agent; in a solid phase: an
effective amount of a thermosetting resin or composition having
a particle size of 1-5 microns; and in a liquid. phase: a liquid
vehicle; wherein said film dispersion remains storage stable at
ambient temperatures and after application said dispersion
forms a physically stable intermediate phase. The article may
optionally include a second substrate or a series of substrates
to forth a composite matrix.
Prior to deposition, the dispersion composition of the
present invention is storage stable. storage stability in
accordance with the present invention means that the level of
particle separation or the degree of particle dispersion
present after storage of the dispersion for the desired period
of~~time remains substantially constant and will. not prevent the
formation ~of an effective bond. Moreover, the dispersion
composition of the present invention remains substantially
unreacted and the solid phase remains partially, if not wholly,
undissolved in the solvsnt over the intended storage period.
After deposition on a substrate but prior to curing, the
composition of the present invention forms an intermediate
film. The intermediate film results from the evaporation of
the liquid vehicle from the composition which, in turn, tends
to congeal the film-forming polymer composition. The
particulate thermoset adhesive becomes cast within the
resulting film.
. .r
~i . -3$-
Prior to curing, the film formed by .the present
composition provides a high degree of physical stability
holding the powdered thermoset material on thQ surface where it
was deposited. This stabilizing character is effective against
mechan~.cal stresses which arise in the environment of use such
as vibration, water or air flow, horizontal or inclined
movement, and prolonged exposure
CA 02152776 1999-08-19
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of the adhesive to ambient atmospheric conditions among other
factors.
Upon curing, the resulting film may become an integral
element of the crosslinked bond or the film-forming polymer
may be fugitive (i.e. may leave or be removed from the bond
site).
Brief Description of the Figure
Figure 1 is a graphical depiction of lap shear strengths
plotted against compositional particle size.
Detailed Description of the Preferred Embodiment
The composition of the present invention comprises a
dispersion having at least two phases containing a
thermosetting composition, a film-forming polymer, and a
liquid vehicle. The first phase comprises a solid powdered
thermosetting composition and may additionally comprise any
of a variety of curing agents, fillers, or added functional
elements as needed. The second phase of the present
composition is a liquid vehicle, a film-forming agents being
provided in the liquid or solid phase. While the film-forming
polymer has been preferably included in the liquid phase it
should be understood that the film-forming agents may be
dissolved in the liquid vehicle or, alternatively, dispersed
in the liquid vehicle as either a liquid a solid. The liquid
vehicle may be aqueous, organic in nature, or a combination
thereof. Optionally, as desired, the liquid phase of the
present composition may also comprise dispersing agents,
thixotropes, wetting agents, or any other variety or
constituents depending on the intended application.
Solid Phase
The first phase of the present invention comprises
a powdered solid composition. The solid powdered phase, in
turn, comprises at least the powdered thermosetting resin and
any needed curing agent in each discrete particle.
Optionally, the solid phase may also comprise
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fillers or the functional material, such as, conductive
particles depending on the intended application.
Thermosetting Composition
The thermosetting composition functions to promote
adhesion to the substrate and to form a cohesively stable
bonding mass after curing. The thermoset composition also
functions together with the film-forming phase of the present
invention as a carrier for any particulate substance included
in the composition such as, for example fillers, electrically
conductive particle or constituents which may add flexibility,
high temperature resistance or any number of other pre-cured
physical characteristics to the liquid adhesive once the film
is formed.
Thermosetting coating powders, with some exceptions, are
based on resins that are cured by addition reactions rather
than condensation reactions. Thermosets are synthetic resins
which solidify or set upon heating and cannot be remelted.
Generally, thermosetting compositions useful in the
present composition are those thermosetting compositions which
can be powdered and which remain stable once combined with the
chosen film-forming polymer and solvent in the liquid pre-
application state.
In sharp contrast, prior art compositions using thermoset
powders having particle sizes in excess of 150 microns may fail
to effectively deposit onto or into the intended surface
especially when applied by methods such as electrostatic
deposition.
The thermoset composition useful in the present invention
are partially or wholly insoluble in the liquid vehicle
comprising a solid phase within the
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dispersion composition. Thermosetting compositions useful in
the present invention are also those which provide chemical
and physical storage stability upon film deposition given
evaporation of the liquid vehicle under elevated heat and
prolonged stability over time in the intermediate film state.
Generally, any well known thermosetting composition can
be used in the present invention. Thermosetting compositions
useful in the present invention include those selected from
the group of polymeric materials consisting of an epoxy, a
polyurethane, a polyester, a bis-maleimide, an acrylic,
mixtures thereof and hybrides thereof among a large number of
other compositions. Also useful in the present invention are
bis-maleimides such as the partial reaction product of the bis
maleimide of methylene dianaline with methylene dianaline.
Examplary thermosetting compositions useful in the
present invention include the reaction product of
orthotolybiguanide known as Casmine and commercially available
from SES Chemicals Inc. and bisphenol A-epichlorohydein
available from Ciba-Geigy Corporation under the commerical
name Araldite* GT 7013 triglycidyl isocyanurate thermosetting
compositions; bisphenol A-epichlorohydrin cured with phenolic
crosslinking agents, the epoxy composition being available
from Ciba-Geigy Corporation Araldite GT 7013 and the phenolic
curing agent being available from Cow Chemical Company under
the brand name DEH 84; aliphatic urethane thermosetting
compositions such as an unblocked isophorone diisocyanate-
Epcaprolactam available from Ruco Polymer Corporation under
the commercial name NI2 which may be used with Rucote HBF
which is a hydroxyl terminated polyester resin also available
from Ruco Chemicals; BTDA thermosetting compositions which are
generally the reaction product of 3,3,4,4-benzophenone
tetracarboxylic dianhydride and a disphenol A-epichlorohydrin;
hybrid thermosetting compositions which are the reaction
product of a carboxylated
*Trademark
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WO 94116027 ~ ' PCT/US93/04679
7
saturated polyester curing agent such as Arakote 3001
available from Ciba-Geigy Corporation and a bisphenol
A-epichlorohydrin; standard bisphenol A-epichlorohydrin
thermosets such as those which are cured with 2-methyl
imidazole; and standard bisphenol A-epichlorohydrin
thermosets which are cured with 2-methyl imidazole and
dicyandiamide.
Preferably, the thermosetting composition used in
the present invention are those selected from the group
consisting of polymerized triglycidyl isocyanurate,
aliphatic urethane thermosets, BTDA cured bisphenol
A-epichlorohydrin thermosets, polyester-bisphenol
A-epichlorohydrin thermoset complexes, 2-
methylimidazole cured bisphenol A-epichlorohydrin
thermosets, and orthotolylbiguanide cured bisphenol
A-epichlorohydrin thermosets. These compositions, as
can be seen in Table I, provide maximum storage
stability in the liquid state when used in the preferred
mode with an aqueous carrier.
Generally, the concentration of the powdered
thermoset may be varied from 5 wt-~ to 95 wt-~ of the
adhesive dispersion, preferably 20 wt-~ to 80 wt-~ of
the adhesive dispersion and most preferably 40 wt-~ to
60 wt-~ of the adhesive dispersion. The concentration
of powdered thermoset in the resulting film will range
from about 30 wt-~ to 95 wt-$, preferably 60 wt-~ to 95
wt-$ and most preferably 80 wt-~ to 95 wt-$ depending on
the specific application. The concentration of
thermoset may range as a percentage of either the liquid
composition or the resulting film outside the range as
provided above depending on the application.
Increasing the concentration of the powdered
thermoset will tend to increase the viscosity of the
aqueous liquid composition depending on the relative
particle size of the powdered thermoset used. A higher
viscosity may be desirable to develop a compositional
consistency of a caulk or putty which may be used as an
CA 02152776 1999-08-19
_8_
adhesive sealing agent for any variety of applications.
Moreover, the use of an increased concentration of powdered
thermoset may be desirable to promote an increased spreading
or wetting of the surface of application once the thermoset
adhesive is heated.
In contrast, reducing the relative concentration of the
powdered thermoset within the composition of the present
invention may reduce the degree of relative bonding strength
in the resulting composition. Moreover, reducing the relative
concentration of the powdered thermoset may potentially allow
for a thinner more uniform film as deposited across the
surface of application.
The present invention allows for varying the
concentration of the thermoset composition within the
dispersion and as a result varying the domain size of each
powdered thermoset particle. The present invention also
allows for the deposition of very fine particle thermoset
powders of 1 to 5 microns. The ability to vary particle
concentration and, in turn, particle domain size combined with
the use of very fine particle size thermosets allows the
resulting adhesive composition to have a higher relative
adhesion than higher particle size thermosets which are
applied in a less uniform manner.
The powdered thermoset may be combined with a curing
agent commonly used to promote cross-linking within the
powdered thermoset. Curing agents commonly known to the art
include melamine such as dialkylmelamine; amides such as
dicyandiamide, adipamide, and isophthalyl diamide; ureas such
as ethylene thiourea or guyanylurea; azides such as
thiosemicarbazide, or adipyl dihydrazide, and isophthalyl
dihydrazide; azoles such as guanazole, or 3 amino-1,2,4
triazole; and anilines such as diethylaniline.
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The curing agents generally useful in the composition of the
present invention are subject to the same stability limitations as
the powdered thermoset resin. Specifically, the curing agent may
be partially or wholly insoluble in the liquid vehicle. However,
the curing agent must have an effective degree of chemical
stability so that the required amount of cross-linking takes place
at the intended point of curing. Accordingly, the curing agent may
be solubilized in the liquid vehicle or remain in powder form with
the powdered thermoset. Crosslinking mechanisms may be
additionally retarded by intentionally including a crosslinking
agent which will be solubilized within the liquid vehicle while
retaining the powdered themoset in the powdered form as a separate
solid phase.
When present, the curing mechanism may be a single curing
agent or any combination of curing agents having a concentration
between about 0.1 wt-o and 50 wt-% of the initial solid phase,
preferably between about 1 wt-% and 30 wt-°s of the initial solid
phase, and most preferably about 5 wt-% and 25 wt-% of the initial
solid phase.
The solid phase may also contain other constituents including
dispersing agents, fillers or any other element which is insoluble
in the liquid phase, remains effectively dispersed in the
composition and provides the intended functional characteristic to
the composition.
Preferably, the solid phase of the invention will comprise a
powdered composition of minimal particle size which comprises both
thermoset and curing agent within each individual powdered
particle. Individual particles may be formed by melt mixing and
extruding thermoset and curing agents below curing temperatures.
The resulting extrudate, in the form of, for example, a rope, a
sheet, etc., may then be particlized. Particle sizes range from
about 5 microns to 1 micron.
As will be reflected in the working examples, and as can be
seen in Figure 1, smaller particle size compositions are
._
-10-
believed to provide more uniform domains and as such result in
higher lap shear strengths.
Liquid Phase
The liquid phase of the present invention generally
comprises the film-forming polymer, a solvent and optionally
solubilized dispersing agents, thixotropes, or hardeners among
other potential constituents, which.-may be wholly or partially
dissolved in the liquid phase Of the~present invEmtion.
Film-Forminq Agent
The function of the.film-forming agent is to carry the
thermoset and deposit it on the surface. After liquid vehicle
removal the film holds the powdered thermosettinq_ composition
on the surface of application. Specifically, the film-forming
polymer may form a liquid solution or an insolub7.e dispersion
in the liquid vehicle (i.e. the film former may be a part of
the dispersed solid phase or in solution as part of the liquid
phase) .
Preferably, the film-forming polymer should not impair
the reactivity of the powdered thermosetting composition. Once
the film-forming polymer is either dispersed or dissolved, the
liquid is applied through any variety of means. The liquid
vehicle may be evaporated from the surface of application and
the powdered thermosetting composition is retained or
encapsulated on the surface by the film-forming polymer. The
film-forming polymer may also be used to provide added
functional character to the pre-cured or post-cured composition
such as, for instance, pre- cured tack, solubil.it:y, adhesion,
or wettability as well as
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WO 94/16027
11
post-cured hardness, or water-resistance.
Generally, compounds useful in the present invention
are organic or inorganic film-forming agent which impart
the intended character to the resulting film.
Generally, thermoplastic resins are preferred
film-forming agents as they soften or melt at a given
temperature, and when cooled, recover the physical and
chemical properties of the original resin.
Generally, the physical and chemical properties of
the original resin as well as any resulting films formed
from the thermoplastic include a variable degree of
plasticized flexibility, easy solubilization and
emulsification in various liquid aqueous and organic
vehicles, variable surface stability and stability
against mechanical forces such as vibration, and
horizontal or inclined movement, various degrees of
stability when subjected to environmental forces such as
heat, wind, or any other number of environmental forces
which might impinge upon the composition within the area
of use or application, various degrees of
pre-application thickness or viscosity depending upon
the choice of liquid vehicle.
At a minimum, any thermoplastic film-forming agent
may be used which encapsulates the powdered
thermosetting composition and does not adversely detract
from the functioning of the thermoset once it is applied
to the intended surface. Compounds and polymers which
may function as film formers include plasticizers,
wetting agents, tackifiers, elastomers, thixotropes, as
well as coalescing agents used alone or with inert
fillers .
Exemplary polymeric film-forming dispersions or
solutions can be made from polymerizing one or more of
the following monomers in a solvent medium, such as,
vinyl acetate, ethylene, acrylic acid, methacrylic acid,
crotonic acid, or itaconic acid; esters of acrylic and
methacrylic acid including methyl esters, ethyl esters,
WO 94/16027
PCT/US93/04679
12
butyl and 2-ethylhexyl esters; as well as styrene,
butadiene, vinyl chloride, vinylidene chloride,
isoprene, and chloroprene.
Synthetic polymers resulting from polymerization of
many of the preceding monomers which are useful as
film-forming elements of the present composition include
generally, polyvinyl alcohol (with varying degrees of
hydrolysis), ethylene/acrylic acid copolymers,
ethylene/maleic anhydride copolymers, and styrene/maleic
anhydride copolymers among others.
Naturally derivativized and naturally occurring
polymers such as casein compositions, natural gum
compositions including karaya gum and guar gum,
cellulosic and ether cellulosic compositions, starch,
protein compositions, and starch-grafted copolymers are
also useful as a film-forming polymer of the present
invention. Inorganic compounds such as sodium silicate
may also be useful as the film-forming agent in the
present invention. Those skilled in the art will
realize that the preceding compounds and polymers are
only exemplary of compounds and polymers which may be
used as film-forming agents in the composition of the
present invention and this list should not be viewed as
limiting.
The concentration of the film-forming polymer used
in the composition of the present invention will
generally range from about 1 to 99 wt-~, preferably
range from about 2 to 50 wt-$, and most preferably range
from about 4 to 7 wt-~ depending on the characteristics
to be imparted to the resulting film and the physical
and chemical characteristic of the powdered thermoset
adhesive. As a percentage of the resulting film, the
film- forming polymer may again generally range from
about 1 to 99 wt-~, preferably range from about 4 to 75
wt-~, and most preferably range from about 8 to 14 wt-~
again depending upon the character and quantity of
powdered thermoset adhesive to be encapsulated within
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WO 94/16027 PCT/US93I04679
13
the film and the desired character which the film is
intended to have in either the pre-cured or post-cured
state.
Generally, the film-forming ability of the polymer
depends on the film's ability to support the powdered
thermoset. However, diminishing or increasing the
concentration of film-forming agent within the
composition of the present invention may limit or
increase, respectively, the thermoplastic character of
the film former and the ability of the film-former to
retain the powdered thermoset on the surface of
application. Moreover, pre-cure and post-cure film
characteristics may be increased or diminished by the
use of, for instance, thixotropes which can be used to
affect changes in the viscosity and flowability of the
composition of the present invention.
Liauid Vehicle
The liquid phase of the present composition also
principally contains a liquid vehicle. The liquid
vehicle facilitates transport and deposition of the
adhesive used in the composition of the present
invention. Use of the liquid vehicle may also allow
reduction of the concentration of the film-forming
component.
Generally, the liquid vehicle may be aqueous,
organic or a mixture thereof. While the liquid vehicle
preferably does not interact with the thermoset, the
liquid vehicle may generally be used to modify the
effect of the thermoset by enhancing or reducing
adhesion.
Organic liquid vehicles useful in the present
invention are limited to those which maintain the
dispersed character of the thermoset within the liquid
phase of the present invention without reacting and
destabilizing either the thermoset or any curing agent
which may be present in the system. Organic liquid
vehicles which function accordingly may partially or
-1 4-
wholly displace any aqueous solvent used in the composition.
Organic liquid vehicles useful in the present invention
include but~are not limited to low molecular weight (600-650
m.w.) fatty acid polymers including dimer and trimer acid
compositions resulting from the polymerization of long chain
(CV24-C40) aliphatic dibasic acids with long chain (C50-C60)
aliphatic tribasic acids polymers such as those fatty
acid polymers available from Emery under_,the Empol brand
name; liquid curing agents including
dicyanamide; liquid epoxy compositions including liquid
bisphenol A-epichlorohydrin low molecular weight epoxies such
as the Epon* brand epoxies available from Shell Chemical
Company; mineral solvents; naptha; and liquid polyamides such
as N-ethyl 0. P-toluene sulfanamide available from Monsanto
Corporation as Saniticizer 8.
Alternatively, the liquid vehicle may be aqueous or an
aqueous-organic solvent mixture. Such a liquid vehicle is
useful in minimizing environmental and safety hazards often
prevalent with the use of volatile organic. Also, a mixture of
aqueous and organic liquid vehicles may be useful in
maintaining, for example, a curing agent and resin in separate
phases and thus increasing the chemical stability and storage
life of the present composition prior to application. Such a
system will comprise a liquid vehicle or combination of liquid
vehicles which may completely solubilize the curing agent yet
retain the thermoset resin in solid undissolved form.
Preferably, if minimal toxicity and flammability is
desired the liquid vehicle is water. Generally, an aqueous or
aqueous-organic may avoid or reduce toxicity and volatility
problems which may be prevalent with certain organics, and is
generally compatible with many known powdered thermoset
adhesive compositions resulting in an unreacted composition
having an extended
*Trademxrk
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shelf life. Water provides a nonreactive environment together
with the film-forming polymer which can be used to store the
powdered adhesive for extended periods of time. Moreover,
water may be readily vaporised to form the thermoset
encapsulating stable intermediate film.
Generally, regardless of the aqueous or organic character
of the liquid vehicle, concentrations of the liquid vehicle
will range from about 1 to 99 wt-%_ of the :liquid dispersion
composition of the present invention, preferably From about 25
to 75 wt-% and most preferably from about 45 to ~i5 ~wt-%.
Varying the concentration of the liquid vehicle promotes
differing characteristics within the composition. For
instance, reducing the concentration of liquid vehicle within
the composition of the present invention may increase the
viscosity of the composition and may provide for a material
which has a physical character somewhat like a paste or a
putty. Such a character is more applicable to environments
which do not require a uniform coating.
In contrast, increasing the concentration of liquid
vehicle within the composition of the present invention may
result in a much less viscous composition. Such ~i formulation
allows for the application of a thinner adhesive coat.
However, higher liquid vehicle concentrations may result in a
settling of the thermoset powder making the composition
inoperable as an adhesive dispersion. As a result, some
thixotropic character is preferred within the composition in
order to provide the proper level of dispersion necessary to
provide an effective adhesive composition.
Dispersing' Agents
Optionally, the composition of the present invention may
also contain a dispersing agent dispersed as a element of the
solid phase or dissolved or dispersed as an element of the
liquid phase. The dispersing agent functions to efficiently
disperse the powdered thermoset
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WO 94/16027 ~ PCT/US93104679
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composition of the present invention when the
film-forming agent alone is not adequate to keep the
powdered thermoset dispersed within the solvent. The
dispersing agent may also assist in forming the stable
intermediate film used to hold the powdered thermoset on
the surface of application prior to curing. Dispersing
agents may also be used to lower surface tension and
modify rheology within the system providing a thermoset
composition which has a higher degree of wettability
once applied to the intended surface.
Dispersing agents which can be used in the
composition of the present invention generally include
any physical or electrical dispersant which is not
deleterious to the stability or curing ability of the
thermoset. The dispersing agents preferably does not
affect the chemical stability of the powdered thermoset
adhesive by reducing shelf life either in the liquid
state or in the solid film state prior to cure but after
the composition is applied. To this end, the
dispersants used in the composition of- the present
invention may either be retained in the film once formed
or vaporized upon evaporation of the liquid vehicle from
the composition or upon curing of the powdered
thermoset.
Solid and liquid dispersing agents which are
exemplary of those useful in the present invention
include those film-forming agents having a dispersing
character disclosed as useful in the liquid phase of the
present composition. Also useful as dispersants in the
present invention are compounds such as complex
phosphates such as sodium hexametaphosphate, sodium
tetraphosphate, sodium tripolyphosphate, and tetrasodium
pyrophosphate; colloidal compositions such as casein,
soybean protein; cellulosic compositions such as
carboxymethyl cellulose, carboxymethyl starch, and
hydroxyethyl starch; silicates, such as sodium
orthosilicate, sodium sesquasilicate, sodium
2 ~ 5 2 7 '~ 6 PCT/US93104679
WO 94/16027
17
methylsilicate, and sodium disilicate; various surface
active agents including nonionic surfactants such as the
condensation products of alkanols or ethylene oxide and
the condensation products of fatty acids and ethylene
oxide, anionic surfactants such as the alkali metal
salts of alkyl or alkyl aryl sulfonic acid, and cationic
surfactants such as alkyl and alkyl aryl quaternary
ammonium salts; as well as miscellaneous other
compositions such as polyacrylate polymers composed of
monomers such as methyl acrylate, ethyl acrylate,
isopropyl acrylate, butyl acrylate or ethyl hexyl
acrylate.
In the liquid state, prior to application of the
composition of the present invention, the concentration
of dispersant within the present invention may generally
vary from 0 wt-$ to 5 wt-~, preferably from 0.5 to 4
wt-~ and most preferably from 1 to 3 wt-~.
Generally, increasing the concentration of
dispersant within the composition of the present
invention tends to decrease the adhesive effect of the
powdered thermoset. Accordingly, a dispersant may be
used to regulate or reduce the bonding ability of the
powdered thermoset adhesive. In sharp contrast,
reducing the concentration of the dispersant may also
result in a settling out of the thermoset powder in
instances where the film-forming composition does not
provide an adequate dispersing effect.
CA 02152776 1999-08-19
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Concentration Ranges in
Liquid Composition
CONSTITUENT USEFUL WORKING PREFERRED
Thermoset 5-95 wt-% 20-80 wt-% 40-60 wt-
Curing Agent 0.1-50 wt-% 1-30 wt-% 5-25 wt-%
(when present)
Film-Forming 1-99 wt-% 2-50 wt-% 4-7 wt-%
Polymer
Liquid Vehicle 1-99 wt-% 25-75 wt-% 45-55 wt-%
Dispersing Agent 0-5 wt-% 0.5-4 wt-% 1-3 wt-%
Particle Size 1-5E.sm 1-5,um 1-SE.sm
Applications
The liquid thermoset dispersion of the present invention
may be incorporated into any number of products useful in a
variety of applications.
The liquid thermoset dispersion of the present invention
can easily be applied onto almost any surface. The liquid
dispersion of the present invention may be cast into or onto
an unidirectional, woven, or nonwoven carrier for a later
application to a substrate or in the formation of a composite
laminate. At the point of application the solvent may be
flashed off or dried from the composition. If the surface is
a unidirectional, woven or nonwoven carrier a film adhesion
impregnate is formed. Generally, tack, drape or the ability
to conform a material to a specific surface, and adhesion can
be varied as desired by varying the concentration of film-
forming agent, and liquid vehicle.
Multiple layers or different or similar materials can be
applied to achieve desired characteristics. The unique
advantage of this type of film adhesive or impregnated
composition is the room temperature stability of the
composition which does not require refrigeration of the
material, specifically, once
WO 94116027
19
PCTIUS93104679
deposited on or in the carrier the powdered thermoset
remains reactive and storage stable for extended periods
of time.
Additionally, the liquid thermoset dispersion may be
used as a film adhesive. In this case, the liquid
dispersion may be cast onto a release liner where the
intermediate film is formed. At a later time the film
adhesive is applied to the intended substrate and the
release liner removed. Furthermore, the liquid
dispersion may be cast into or onto a unidirectional,
woven, or nonwoven carrier and then combined with a
release liner. In application the composite complete
with the release liner is applied onto a substrate and
the release liner is~then removed from the composite
system.
The adhesive composition of the present invention
can be loaded into or onto a woven or nonwoven carrier
which could be used by itself or in a multiple layer
composite system for the fabrication of a rigid
composite laminate. Carrier systems commonly used in
the formation of a composite include but are not
limited to nonwoven carriers such as glass or polyester
mats. Unidirectional or woven carriers include but are
not limited to carbon, ceramic, thermoplastic, aramide,
natural clothing fibers such as wool or cotton,
synthetic clothing fibers, glass fibers and hybrids
thereof .
The systems may be used in any number of
applications by providing an adhesive with or without a
carrier as well as including any number of additives in
the adhesive composition. For instance, these systems
could be used to replace sewing by heat sealing fabrics,
the unused thermoset being washed out after the fusing
processes are completed. This composition may be used
to precoat metal against corrosion by forming the
intermediate thermoset film on a substrate and then
structurally bonding additional substrates to the '
-20-
surface of application by heat activating and curing the
thermoset.
The easy application of the composition of the present
invention allows the adhesive to be used as a primer for
application to surfaces having a lower affinity for accepting
a continuous adhesive layer. Intumescents or flame retardants
may be used in the adhesive composition of the present
invention which once applied may additionally function to
protect the substrates carrying the adhesive layer.
Additionally, hydrophobic particulate elements may .be included
within the composition of the present invention to define a
resulting bond which is highly water resistant. These
applications are only representative of the number of uses for
the composition of the present invention.
Working Examples
The Working Examples of the present invention were
formulated first as solid phase premixes comprising dry
thermoset compositions additionally containing curing agents,
preservatives, defoamers, and fillers among other agents. The
premixes were then used in the formulation of the two phase
dispersed liquid systems of the present invention.
Premixes
An initial step in preparing the thermoset adhesive
compositions of the present invention was the preparation of
dry powdered thermoset adhesive premix compositions. Premix
compositions 1-9 were prepared by dry mixing the various
elements listed under each formulation. Once the dry mixing
was completed the compositions were melted and then screw
extruded and cast into a uniform sheet. Once solidified, the
premix compositions were pulverized into a fine powder. The
premix compositions were either taken from production runs of
295.6 to 454.8 Kg (650 to 1,000 pounds) each or taken from lab
batches which were made 1,000 grams at a time.
a~,
a:
-H.3~1 1
WO 94/16027 , PCTIUS93I04679
21
PRE-MIX 1
Ingredient Parts By
Weight
RUCOTE*HBF (Aliphatic-urethane 80.3213
epoxy reaction product of
unblocked isopherone diisocyanate-
E-caprolactone monomer commercially
available from Ruco Polymer
Corporation)
2 Methyl Imidazole 17.6707
RESIFLOW*P-67 (acrylate/silicon ~ 1.2048
dioxide compound commercially
available from Estron Chemical, Inc.)
Benzoin 0.8032
PRE-MIX 2
Ingredient Parts By Weight
ARAKOTE~3010 (carboxylated 90.9091
saturated polyester resin
commercially available from
Ciba-Geigy Corporation)
triglycidyl isocyanurate 6.8426
RESIFLOW P-67 (acrylate~silicon 1.4663
dioxide compound commercially
available from Estron Chemical,
Inc.)
Benzoin 0.7820
*Trademark
t.
WO 94/16027 ~ PCTIUS93/04679
22
PRE-MIX 3
Ingredient Parts By Weight
Araldite GT 7013 (bisphenol 58.6262
A-epichlorohydrin commercially
available from Ciba-Geigy
Corporation
ARAKOTE 3001 (carboxylated saturate 37.9839
polyester resin commercially
available from Ciba-Geigy
Corporation)
RESIFLOW P-67 (acrylate~silicon 1.6910
dioxide compound commercially
available from Estron Chemicals,
Inc.)
Benzoin ~ 0.9813
XB-3126 (curing accelerator 0.7136
commercially available from
Ciba-Geigy)
Ingredient Parts By Weight
Araldite GT 7013 (Bisphenol A- 93.3707
Epichlorohydin commercially
available from Ciba-Geigy
Corporation)
Orthotolylbiguanide 1.8553
Benzoin 0.8735
RESIFLOW P-67 (acrylate~silicon 1.4006
dioxide compound commercially
available from Estron Chemicals,
Inc.)
t...a~'
WO 94/16027 ~ PCTlUS93104679
._
23
PRE-MIX 5
Ingredient Parts By Weight
Araldite GT 7013 (Bisphenol A- 97.9132
Epichlorohydrin commercially
available from Ciba-Geigy
Corporation)
2 methylimidazole 0.5877
RESIFLOW P-67 (acrylate/silicon 1.4691
dioxide compound commercially
available from Estron Chemicals,
Inc.)
PRE-MIX 6
Ingredient Parts By Weight
Araldite GT 7013 (bisphenol A- 94.1620
epichlorohydrin commercially
available from Ciba-Geigy
Corporation)
2-methylimidazole 0.1883
dicyandiamide 4.2373
RESIFLOW P-67 (acrylate/silicon ~ 1.4124
dioxide compound commercially
available from Estron Chemicals,
Inc.)
PRE-MIX 7
Ingredient Parts By Weight
Araldite GT 7013 (bisphenol 85.7633
A-epichlorohydrin commercially
available from Ciba-Geigy
Corporation)
3,3,4,4-Benzophenone 11.14192
Tetracarboxylic
Dianhydride
RESIFLOW P-67 (acrylate/silicon 1.2865
dioxide compound commercially
available from Estron Chemical,
Inc.)
Benzoin ' 0.6861
OCTAFLOW*ST70 (stannous 1.1149
octoate/amorphous silica
catalyst commercially
available from Estron
Chemical, Inc.)
.- *Trademark
~c
_24
PRE-MIX 8
Ingredient _ Parts by Weight
Aralidite GT 7013 (bisphenol 72.8332
A-epichlorohydrin commercially
available from Ciba-Geigy Corporation)
DEH 84 (phenolic curing . 25.4916
commercially available
from Dow Chemical Company)
RESIFLOW P-67 (acrylat:e/silicon - 1.0925
dioxide compound commercially
available from Estron
Chemicals, Inc.)
Benzoin 0.5827
PRE-MIX 9
Ingredient Parts by Weight
Shell*2002
60.1400
(bisphenol A-
epichlorohydrin commercially
available from Shell Chemical
Company)
Dicyandiamide 1.4700
Epon P101 Curing Agent (amine 0.6300
condensate of an epoxy resin
commercially available from
Shell Oil Company)
RESIFLOW P-67 (acrylate/silicon 0.8700
dioxide compound commercially
available from Estron Chemical, Inc.)
Pigments (titanium dioxide and 30.0030
carbozole violet)
Barium Sulfate 5.8870
1 Tetramethyl decynediol 1.0000
Storage Stability
The solid phase premix formulations were thEm formulated
into aqueous dispersion compositions generally comprising
43
parts powdered premix, 50.5 parts water as a liquidvehicle,
5
parts of a vinyl acrylic latex binder composition (available
from Union Oil Company as 76 Res 661), and 1.5 parts of
a
magnesium
*Trademark
WO 94!16027 PCT/US93104679
aluminum silicate thixotrope and defoamer comprising a
blend of emulsifiable mineral oils, silica derivatives
and esters (available from Drew Chemical Company as
surfactant Y-250). The resulting compositions were then
5 subjected to stability testing at room temperature
(approximately 25" C.) over a period of 100 days.
TABLE I
WORKING EXAMPLE MATERIAL STABILITY AT ROOM
TEMPERATURE
10 Aqueous Consistency
24 Hours 10 Days 100 Days
1 Ok - low Ok - low Ok
15 (Premix 4) visc. visc.
2 Ok - low Ok - low Ok
(Premix 2) visc. visc.
20 3 Ok - law Ok - low Ok
(Premix 1) visc. visc.
4 Ok - low Ok - low Ok
(Premix 3) visc. visc.
5 Very Ok - low Ok
(Premix 5) thix. visc.
As can be seen, the compositions reported in Table I
had a stability of at least to 100 days. While other
premix formulations did not provide this degree of
storage stability, these dispersions did provide
compositions useful for applications which allowed for,
or required, more immediate deposition on the intended
surface.
Another set of Working Examples, Numbers 6-22 were
then prepared using the premix formulations previously
prepared. Generally, the Working Examples were prepared
in three steps. First, a liquid vehicle, was introduced
into a mixing vessel with an appropriate amount of
surfactant. Once the surfactant was~dispersed in the
liquid vehicle a dispersant and the intended premix
formulation was added to the mixture. Once the premix
was fully dispersed, an additional amount of thixotrope
WO 94/16027 - PCT/US93/04679
26
and liquid vehicle was added to the mix and stirred
until homogeneous.
WORKING EXAMPLE 6
Ingredient Parts By Weight
HZO 49.50
Defoamer (Blend of .50
emulsifiable mineral oils,
10silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 4 43.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
20Magnesium Aluminum 1.00
Silicate (5~ w/v)
WORKING EXAMPLE 7
Ingredient Parts By Weight
g2p 4 9 . 5 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 2 43.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5~ w/v)
~15~~76
WO 94/16027 PCT/US93/04679
27
WORKING EXAMPLE 8
Ingredient Parts By Weight
H20 4 9 . 5 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 8 4.3.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5~ w/v)
WORKING EXAMPLE 9
Ingredient Parts By Weight
H20 4 9 . 5 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 1 43.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5~k w/v)
WO 94/16027 ~ PCT/US93104679
28
WORKING EXAMPLE 10
Ingredient Parts By Weight
H20 4 9 . 5 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 3 43.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5~ w/v)
WORKING EXAMPLE 11
Ingredient Parts By Weight
H20 4 9 . 5 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 5 43.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5$ w/v)
21 ~ ~'~'~ 6
WO 94/16027 PCT/US93104679
29
WORKING EXAMPLE 12
Ingredient Parts By Weight
H20 4 9 . 5
0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 6 43.00
76 RES 661 (vinyl 6.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5~ w/v)
WORKING EXAMPLE 13
Incrredient Parts By Weight
H20 5 0 . 5 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 6 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 1.00
Silicate (5~ w/v)
WO 94/16027 PCT/US93/04679
WORKING EXAMPLE 14
Ingredient Parts By Weight
5 Hz0 51.00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
10 available from Drew Chemical
Company as blend Y-250)
Pxe-Mix 4 43.00
15 76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
20 Silicate (5~k w/v)
WORKING EXAMPLE 15
25
Ingredient Parts By Weight
HZO 51. 00
30 Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 2 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5$ w/v)
21 ~ 2'~'~ ~
WO 94!16027 PCT/US93I04679
31
WORKING ERAMPLE 16
Inctredient Parts By Weight
H20 51.00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 8 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5~ w/v)
WORKING ERAMPI~E 17
Ingredient Parts By Weight
Hz0 51. 00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 1 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5~ w/v)
WO 94/16027 ~ PCT/US93104679
32
WORKING EXAMPLE 18
Ingredient Parts By Weight
H20 51. 00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 7 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5~ w/v)
WORKING EXAMPLE 19
Ingredient Parts By Weight
H20 51. 00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 3 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5~ w/v)
WO 94116027 ~ PCTIUS93104679
33
WORKING EXAMPLE 20
Ingredient Parts By Weight
HZO 51. 0 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 5 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5~ w/v) .
WORKING EXAMPLE 21
Ingredient Parts By Weight
H20 51. 00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 9 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
Magnesium Aluminum 0.50
Silicate (5~ w/v)
34
WORKING EXAMPLE 22
Ingredient Parts by Weight
Hz0 51 . 00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 2 ~ 43.00
Gion Brand 5.00
acrylonitrile latex
butadiene styrene terpolymer
(commercially available from
B. F. Goodrich)
Magnesium Aluminium 0.50
Silicate (5o w/v)
Cured Strength
In working Examples 23-26 a slightly different mixing
process was used. First a surfactant was dispersed in a liquid
vehicle after which the powdered adhesive premix and a
dispensing agent were mixed slowly into the composition. The
strength of these compositions was then tested and is shown in
Table II.
WORKING EXAMPLE 23
Ingredient Parts by Weight
H20
4 5 . 0 0
Defoamer (Blend of
.50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250) '
Pre-mix 4
43.00
76 RES 661 (vinyl
5.00
acrylic latex copolymer
available from Union Oil Corp.
s' ~.
PCT/US93/04679
WO 94/16027
WORKING EXAMPLE 24
Ingredient Parts By Weight
5 H20 4 5 . 0 0
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
10 available from Drew Chemical
Company as blend Y-250)
Pre-Mix 2 43.00
15 76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
20 WORKING EXAMPLE 25
Ingredient Parts By Weight
H20 45.00
25
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
30 Company as blend Y-250)
Pre-Mix 8 43.00
76 RES 661 (vinyl 5.00
35 acrylic latex copolymer
available from Union Oil Corp.)
WORKING EXAMPLE 26
Ingredient Parts By Weight
H20 45.00
Defoamer (Blend of .50
emulsifiable mineral oils,
silica derivatives and esters
available from Drew Chemical
Company as blend Y-250)
Pre-Mix 2 43.00
76 RES 661 (vinyl 5.00
acrylic latex copolymer
available from Union Oil Corp.)
36
Cured Bond Strength
The lap sheer strength and T-Peel strength Working
Examples 23 through 26 was then compared with the following
results provided in Table II.
TABLE II
Lap Sheer
Working Example Strength T-Peel Strength
kg-force/cm' N/m
(lb/in') (lb~/inch width
init./open 2 days)
23 169.7~ 19.3 75.9/116.7
(2413.7 ~ 275) (5.2/8.0)
24 (cohesive) 272.7 ~ 24.8 157.6/106.5
(3878.4 ~ 352.8) (10.8/7.3)
25 (adhesive) 267.9 ~ 6.9 131.3/102.1
(3810.7 ~ 96.5) (9.0/7.0)
26 (cohesive) 303.9 ~ 29.5 160.5/68.6
(4322.2 ~ 419.4) (11.0/4.7)
As can be seen from Table II Working Examples 23-26
showed substantial lap sheer strength and T-Peel strength both
initially and after two days. Working Examples 24 and 26
provided a cohesive bond where upon failure, the bond was split
evenly down the middle leaving adhesive material on both
substrates. Working Example 25 provided an adhesive bond
leaving areas on both substrates where the adhesive material
was completely stripped from the surface of application.
r
-37-
Lapsheer Strength as a
Function of Particle Size
A tenth premix was formulated as shown below:
Material Premix 10 WT-
Araldite GT 7013 (bisphenol A- 75.4717
epichlorohydrin available from
Ciga-Geigy Corporation)
P-101 Curing Agent (Amine 2.6415
Condensate of an epoxy resin -.
available from Shell Oil Company)
RESIFLOW P-67 . 1.1321
(acrylate/silicon dioxide
compound available from
Estron Chemicals, Inc.)
x
Uraflow B (benzoin flow agent, 0.7517
GCA Chemical Co.)
BARTEX X65 , 1 8 . 8679
Chromalloy Industrial
Minerals)
Pigments (Black beads) 1.1321
An eleventh premix was formulated as shown below:
Pre-Mix 11
Material Wt-
Araldite GT 7013 (bisphanol A- 94.1620
epichlorohydrin available from
Ciba-Geigy Corporation)
2-methylimidazole 0.1883
dicyandiamide 4.2373
RESIFLOW P-67 1.4124
(acrylate/silicon dioxide
compound available from
Estron Chemicals, Inc.)
The premixes were then used in the thermosetting
compositions shown in Table 3. In each instance, the particle
size of the_powder coating used in the composite is shown in
Table III.
*T~'ademark
38
Table III
Formulations regarding micron size:
3 Micron 4.9 Micron 62 Micron 103 Micron
8% 8% 8% 8%
Carboxylated Carboxylated Carboxylated Carboxylated
Acrylic Acrylic Acrylic - Acrylic
Copolymer Copolymer Copolymer Copolymer
44% Premix 44% Premix 11 44% Premix 11 44% Premix 11
.4% TAMOLk850.4% TAMOL~~850 .4% TAMOL*850 ~ .4% TAMOL 850
~
(Sodium Salt (Sodium Salt (Sodium Salt (Sodium Salt
of Polymeric of Polymeric of Polymeric of Polymeric
Carboxylic Carboxylic Carboxylic Carboxylic
Acid Acid Acid Acid
Dispersing Dispersing Dispersing Dispersing
Agent; Rohm Agent; Rohm Agent; Rohm Agent; Rohm
& Haas & Haas & Haas & Haas
47 . 48&H20 47 . 6 % Hz0 47 . 48 % H,0 47 . 48 % H20
.03% XANTHAN .03% XANTHAM .03% XANTHAM
GUM GUM GUM
.09% Guar Gum .09% Guar Gum .09% Guar Gum
Aluminium lapshears were. wiped with methyl ethyl ketone,
acid etched for ten minutes and washed in deionized water
before being air dried. Lapshears were assembled with 7781
volan (registered trade mark) fiberglass cloth which was
impregnated with products above. Coat weights were 28% by
weight of epoxy powder. The impregnated cloth was sandwiched
between the lapshears and cured for one hour at 177°C at 6.9 x
1 0'' Pa ( 350°F at 1 , 000 psi ) . Lapshears were evaluated using
ASTM D1002-72.
As can be seen in Figure One, 3 micron and 4,9 micron
particle size compositions were compared to 62 and 103 micron
formulations to determine lapshear strength. The difference in
strength with smaller particle size compositions was notable.
The above discussion, Examples and data illustrate our
current understanding of the invention. However, since many
variations of the invention can be made without
*Trademark
-39-
departing from the scope of the invention, the invention
resides wholly in the claims hereinafter appended.
'r~ ~'
