Note: Descriptions are shown in the official language in which they were submitted.
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57772.318
CURA~LE RESIN COMPOSITIONS
AND PROCES8 FOR THE PREPARATION THEREOF
FIELD OF THE INVENTION
This invention relates to new and improved
amine-terminated polyamide/epoxy resin compositions
useful as curable hot-melt adhesives, which compositions
contain a diluent which reduces the polyamide melt
viscosity without adversely affecting the composition
strength. This invention further relates to the process
of manufacture of the compositions useful as hot-melt
adhesives.
DESCRIPTION OF RELATED ~RT
U.S. Patent No. 2,705,223 (Renfrew et al.) relates
to the curing of mixtures of polyamide resins and
complex epoxides. The polyamides comprise the
condensation products of polymeric fatty acids with
aliphatic polyamines. Compositions varying from 10~
epoxy resin and 90% polyamide resin to 90% epoxy resin
and 10% polyamide resin are disclosed. The emphasis was
on higher amine number polyamides and the use of those
resins for coatings.
U.S. Patent No. 4,082,708 (Mehta) discloses
bisamino piperazine containing thermoplastic polyamides
which are reacted with epoxides to provide a quick set
hot-melt composition. The polyamide is derived
substantially from bisamino piperazine.
U.S. Patent No. 2,867,592 (Morris et al.) disclose
thermoplastic polyamide epoxy adhesives prepared from
polymeric fatty acids. The materials of Morris are
limited in epoxy content and are not thermoset.
U.S. Patent No. 3,488,665 (MacGrandle, et al.)
teaches a process wherein polyamides are blended with
epoxies to provide a product which cures after reaction
.~ , ,
. : . :
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with another polyamide. Example 1 in the patent implies
that excess epoxy resin with acid-terminated polyamides
reacts only to a limited extent when heated. We have
found that these mixtures continue to cure when heated,
implying that one of the components in the mixture is
not stable.
Two component thermosettable epoxy adhesive
compositions thus are well known, as are the curable
liquid epoxides and liquid polyamide curing agents. It
is also well known in the art that relatively high amine
number and medium molecular weight polyamides can be
reacted with epoxy resins to form thermoset systems with
reasonable flexibility, impact resistance, and tensile
shear strength. The reaction, however, is often very
slow. The reaction rate can be increased by using
relatively lower molecular weight and higher amine
number polyamides; however, when reacted with epoxy
resins, the resultant thermoset generally lacks the
desirable flexible qualities of the materials made from
higher molecular weight polyamides. Also, these
materials are liquids, and therefore have little green
(initial) strength until cured.
EP-A-442700 discloses that good green and cured
strength, as well as flexibility, can be obtained by
reacting high molecular weight, low amine number hot-
melt polyamides with low levels of epoxies.
It is desirable to provide for improved mixing of
the polyamide (3,000-5,000 cps at 190C) and epoxy
resins (200-400 cps at 190C) prior to curing in a hot-
melt thermosetting system. One method of accomplishingthis is to use a lower molecular weight polyamide to
minimize the differential viscosity between the
polyamide and epoxy components. Unfortunately, however,
the lower molecular weight polyamides, while serving the
purpose of reducing the viscosity, also pose additional
problems in a hot-melt thermoset system. If a lower
molecular weight polyamide with a relatively low amine
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number is used, the resultant adhesive system does not
possess adequate initial adhesive strength quality,
known to those skilled in the art as green strength, for
adhesive systems. If a higher amine number polyamide
which has a similar lower molecular weight is used to
improve the green strength, the resultant adhesive tends
to cure too quickly, and thus is not conducive to hot-
melt thermoset adhesive systems.
There exists, then, a need for a hot-melt thermoset
adhesive composition which provides for improved mixing
of the polyamide and epoxy resins prior to curing
without adversely affecting the strength properties of
the adhesive.
SUMMA~Y OF THE INVENTION
It has now been found that the addition of a
controlled amount of a diluent to a polyamide resin
permits the reduction in the melt viscosity of the
polyamide resin, thereby allowing use of a lower
viscosity polyamide in a hot-melt, thermoset adhesive
composition without sacrificing physical properties of
the adhesive composition such as green strength and
cured strength.
The present invention provides an improved
thermosetting adhesive composition comprising a
thermoplastic, substantially amine-terminated polyamide,
a diluent, and an epoxy resin, wherein the epoxy resin
has at least two epoxy groups per molecule of epoxy
resin; the polyamide has an amine number greater than
about 1 and less than about 50 and has an excess of
amine groups to acid groups; and the diluent contains a
polar group and has a molecular weight effective to
reduce the melt viscosity of the polyamide resin without
adversely affecting the strength of the thermoset
adhesive composition. The diluent provides for improved
mixing of the polyamide and epoxy prior to curing of the
thermoset adhesive composition.
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DETAILED DESCRIPTION OF THE INVENTION
The invention pertains to an improved resin
composition useful as a thermoset adhesive, said
composition comprising a thermoplastic, substan_ially
amine-terminated polyamide, an epoxy and a diluent. The
polyamide resin has an amine plus acid number greater
than about 1 and less than about 50 and also has an
excess of amine groups to acid groups. The epoxy resin
has at least two epoxy groups per molecule of epoxy
resin. The initial ratio of epoxy groups to total free
amine groups is greater than about 1:1 and less than
about 10:1. Thus, each free amine group becomes reacted
with an epoxy group, thereby linking the polyamide
chains into the epoxy network.
As noted above, in compositions of the present
invention, the polyamide should have an amine plus acid
number greater than about 1 and less than about 50 and
also have an excess of amine to acid groups. Preferably,
the polyamide should have an amine plus acid number
greater than about 2 and less than about 30 and more
preferably, less than about 20, (the amine functionality
is expressed in a conventional manner in terms of mg. of
equivalent KOH/g of sample.) Preferably, the number of
amine groups of the polyamide resin should be from about
51% to 99% of the total number of acid and amine groups.
With lower functionality, the groups are too dispersed
to cure sufficiently. With higher functionality, there
is risk of premature gelation or at least excessive
viscosity. For better green strength, the polyamides
should also have a softening point above about 50C,
preferably between about 75C to about 200C.
In preferred compositions of the present invention,
the polyamides are made from polymerized fatty acids;
linear dicarboxylic acids; and linear, branched, or
cyclic polyamines or mixtures thereof. As used herein,
"polymerized fatty acids" refers to those acids known
commercially as "dimer acid", or to non-linear
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dicarboxylic acid, especially non-linear dicarboxylic
acids having 21 to 44 carbon atoms. A monocarboxylic
acid may be added in order to change the ratio of amine
to acid groups, and/or to control the molecular weight
of the polyamide.
The polyamide compositions of the invention can be
made using 30-100 percent equivalent (i.e., 30-100% of
the total acid groups present in the mixture before
polymerization are derived from the dimer component) of
any polymerized, unsaturated fatty acid or the reaction
product of an acrylic acid with unsaturated fatty acids.
Preferably, the polyamide compositions are made using
50-go equivalent percent of the polymerized fatty acid.
Most preferable is a polymerized, unsaturated fatty acid
having a dimeric fatty acid content greater than about
65 percent by weight.
The term "dimer acid" refers to polymeric or
oligomeric fatty acids typically made by addition
polymerization of unsaturated tall oil fatty acids.
These polymeric fatty acids typically have the
composition 0-10% Cl8 monobasic acids, 60-95% C36 dibasic
acids, and 1-35% Cs4 tribasic and higher polymeric acids.
The relative ratios of monomer, dimer, trimer and higher
polymers in unfractionated "dimer acid" are dependent on
the nature of the starting material and the conditions
of polymerization and distillation. Methods for the
polymerization of unsaturated fatty acids are described,
for example, in U.S. Patent No. 3,157,681. The dimer
content is also controlled by the fractionation
conditions used to reduce the monomer, trimer and higher
polymer components.
Linear dicarboxylic acids may be added in amounts
up to about 70 equivalent percent, preferably 10-50
equivalent percent, and have from 6 to about 22 carbon
atoms. Preferred linear dicarboxylic acids include
oxalic, malonic, succinic and suberic acids. More
preferred are adipic, azelaic, sebacic and dodecanedioic
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acids.
Monocarboxylic acids may be added in amounts up to
about 10 equivalent percent to control molecular weight.
Preferred monocarboxylic acids are linear and have 2 to
22 carbon atoms. Most preferred are stearic, tall oil
fatty and oleic acids.
Linear, branched, or cyclic polyamines, or mixtures
thereof are added in amounts of from about 100
equivalent percent up to about 120 equivalent percent,
based upon total acid groups added to the
polymerization, more preferably from about 100
equivalent percent up to about 115 equivalent percent,
and have from 2 to 50 carbon atoms. The polyamines are
mainly diamines. Preferred aliphatic polyamines include
ethylenediamine, diaminopropane, diaminobutane,
diaminopentane, hexamethylenediamine,
methylpentamethylenediamine, methylnonanediamine,
piperazine, dipiperazine, aminoethylpiperazine,
bis(aminoethyl)piperazine, bis(aminomethyl)cyclohexane,
and dimer diamine (diamine made from dimer acid).
Xylenediamine and bis(aminomethyl)benzene are also
useful. Most preferred are ethylenediamine,
hexamethylenediamine, piperazine,
methylpentamethylenediamine, dimer diamine, and
polyetherdiamines.
Polyetherdiamines provide products with better flow
properties. Polyetherdiamines are added in amounts of
from 2 to 60 equivalent percent, and more preferably
from 5 to 40 equivalent percent. The most preferred
polyetherdiamines include diamines made from propylene
oxide polymers having molecular weights of from 100 to
about 8000, diamines made from ethylene oxide polymers
having molecular weights of from 100 to about 8000, and
diamines made from ethylene oxidepropylene oxide
polymers having molecular weights of from 100 to about
8000. Other suitable polyetherdiamines include
triamines made from propylene oxide polymers or ethylene
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oxide polymers and having molecular weights of from 100
to about 8000. Typical commercial products are
JeffamineTM D-230, D-400, D-4000, ED-600, ED-900,
ED-2001, ED-4000, ED-6000, T-403, and ER-148 (Texaco
Chemical Company, Bellaire, Texas).
Monoamines may also be added in an amount up to 10
equivalent percent to control molecular weight and
functionality. Up to about 30 equivalent percent of
higher polyamines such as diethylenetriamine,
triethylenetetraamine, and tetraethylenepentaamine, may
be used. Mixtures of polyamines can also be used to
obtain a good balance of properties.
Methods for preparing the polyamides used in the
adhesive compositions of the present invention are
generally known in the art and are exemplified in the
appended examples. Suitable polyamides are commercially
available; for example, UNI-REZTM 2636, 2643, 2646, 2648,
2654, and 2656 (Union Camp Corporation, Wayne, New
Jersey).
The diluent comprises a polar group and has a
molecular weight which is sufficiently high to maintain
the volatility at a level such that the diluent can be
used in a hot-melt adhesive application without "boiling
off". The molecular weight must be low enough to reduce
the melt viscosity of the polyamide resin in the hot-
melt adhesive composition. Preferably the molecular
weight of the diluent will be from about 200 to 900.
The boiling point of the diluent will preferably be
greater than 290C. The weight ratio of polyamide to
diluent is preferably from about 100:1 to about 4:1,
more preferably from about 35:1 to about 6:1.
Generally, any amine, amide, ester, ether, or
sulfide which has the requisite characteristics of
molecular weight and boiling point and which acts to
reduce the viscosity of the polyamide resin withoutadversely affecting the physical strength properties of
the adhesive composition may be used. Preferably the
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diluent will be selected from the group consisting of
RNH2 , RNHCH2CH2CH2NH2 and R-X-R'; wherein R and R ' are any
C14-C24 aliphatic hydrocarbons, and X is selected from the
group consisting of
O O O O
1~ 11 11 11
NH, CO, CNH, and CNHCH2CH2NHC.
Preferred amine diluents are tallowamine,
ditallowamine, and di(hydrogenatedtallow)amine.
Diamines such as tallowaminopropylamine and dimer
diamine are also useful as diluents. Both primary and
secondary amines may be used as diluents. Generally,
monoamines are preferred over diamines. Most
preferably, secondary monoamines, such as
ditallowamines, are used. Preferred amides which may be
used include stearyl stearamide and ethylene
bisstearamide. By way of example, stearyl stearate is a
preferred ester used in adhesive compositions of the
present invention.
The present invention is applicable to epoxy resins
having two or more epoxy groups per molecule of epoxy
resin. The most preferred epoxy resins have from 2.2 to
8 epoxy groups per molecule. The epoxy compositions
which may be used for curing are generally linear
epoxies based upon the diglycidyl ether of bisphenol A
or bisphenol A oligomers, or branched types based upon
the multiglycidyl ethers of phenolformaldehyde or
cresol-formaldehyde resins, or epoxidized olefins,
including unsaturated fatty oils. The most preferred
epoxy resins are multifunctional epoxy novalac resins,
such as the D.E.N. TM epoxy novalac resins sold by the Dow
Chemical Company (Midland, Michigan). D.E.N. 431 has an
average of 2.2 epoxy groups per molecule, D.E.N. 438 has
an average functionality of 3.6, and D.E.N. 439 resin
has an average functionality of 3.8.
The initial ratio of epoxy groups of the epoxy
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resin to free amine groups is greater than about 1:1 and
less than about 10:1. It is preferred that the ratio of
epoxy groups to free amine groups be greater than about
1:1 and less than about 5:1. The most preferred ratio
of epoxy groups to free amine groups is greater than
about 1.5:1 and less than about 5:1.
The application and curing of the diluent-
polyamide-epoxy resin composition is effected very
simply. The polyamide resin, diluent, and epoxy resin
may be melted separately, subsequently mixed together
and then coated upon the substrate as a molten mixture.
The molten polyamide resin, molten diluent and molten
epoxy resin may be combined simultaneously. Preferably,
the molten polyamide resin and molten diluent are mixed
together to form a molten mixture of the two. The
molten mixture is then combined with the molten epoxy to
form the thermoset adhesive composition. Alternatively,
the polyamide resin may be dry-blended with the diluent
and melted when needed to combine with the molten epoxy
resin. The reaction temperature will generally not
exceed 220C, since at higher temperatures some cracking
or premature polymerization of the reaction product will
occur. Of course, a coating of the molten thermoset
adhesive composition may be applied upon any or all
areas or surfaces of one or more substrates.
The resultant product, after application and upon
cooling, is a thermoset having good initial adhesive
strength at room temperature, commonly referred to as
green strength. The term thermoset, as used herein,
denotes a material that either will undergo or has
undergone a chemical reaction by the action of heat,
catalysts, ultraviolet light or other means, leading to
a relatively infusible state. Upon curing, the
thermoset adhesive composition demonstrates improved
organic solvent resistivity, water resistivity and heat
resistivity. This thermoset adhesive is more ductile
and flexible, provides longer working times, and will
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bond to most plastics. In adclition, the thermoset
adhesive compositions provide improved bonding to
substrates at ambient temperatures and substrates having
smooth surfaces, both of which are generally more
difficul.t to bond.
It will be evident to one skilled in the art of
adhesive formulation that other additives such as
fillers, reinforcing agents, coupling agents, colorants,
odorants, other comonomers, resins, tackifiers,
plasticizers, lubricants, stabilizers, antistats, and
the like can optionally be added. In addition,
antioxidants can be added at any point during the
reaction sequence.
The invention will be made clearer by reference to
the following examples. These examples are presented
for the purpose of illustration and are not to be
construed as limiting the appended claims.
Examination of the following examples and review of
the resulting data will make two points particularly
apparent. First, addition of the diluent to the
polyamide, thereby reducing the viscosity of the
polyamide prior to mixing with the epoxy, while
adversely affecting the physical properties of the
uncured polyamide resin (Example l(a) v. l(b)), does not
cause significant loss of physical properties of the
cured, thermoset adhesive composition, such as vinyl T-
peel, lap shear strength, or tensile at ambient or 60C.
Secondly, in relationship to a polyamide-epoxy thermoset
made with a lower viscosity polyamide to which a diluent
has been added, a polyamide-epoxy thermoset made from
the lower viscosity polyamide without the diluent is
significantly weaker in all of these properties.
Example l(a): Control; Uncured Polyamide
Example l(a) concerns a control sample of an
uncured, amine-terminated polyamide, UNI-REZTM 2636
(Union Camp Corp., Wayne, New Jersey), which is prepared
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commercially from dimer acid, co-diacid,
ethylenediamine, piperazine, and polyetherdiamine. This
polyamide had an acid number of 0.6 and an amine number
of 7.6. The viscosity of the polyamide was measured at
190C, and the softening point was determined by
standard ASTM ring and ball softening point methods,
results of which are found in Table 2.
Fifty grams of UNI-REZ 2636 were placed into a
metal container. The metal container was put into an
oven preheated to a temperature of 190C. The container
was removed when the polyamide became molten. The
resulting molten polyamide was poured onto release paper
and allowed to cool. Tensile samples were prepared
according to methods outlined in Example 2 and tensile
tests were conducted at 23C after 24-hour storage at
23C and 50% humidity, and at 60C after 24-hour storage
in 60C water (Table 3).
Example l(b): Comparative; Uncured Polyamide
with Ditallowamine
Fifty grams of UNI-REZ 2636 were placed into a
metal container and 10 weight percent (based on the
polyamide resin) of ditallowamine (Sherex A-240) were
added to the UNI-REZ 2636. The metal container was put
into an oven preheated to a temperature of 190C. The
metal container was removed when the polyamide/diluent
mixture became molten. The resulting molten mixture was
poured onto release paper and allowed to cool. Tensile
tests were conducted according to conditions outlined in
Example l(a) above (Table 3).
Example 2: Comparative; Epoxy-Cured Polyamide
Fifty grams of UNI-REZ 2636 were placed into a
metal container. The metal container was put into an
oven preheated to a temperature of 190C. The container
was removed when the polyamide became molten. Five
grams of epoxy resin (D.E.N. 439) were immediately and
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thoroughly mixed into the polyamide. The resulting
molten mixture was poured onto release paper and allowed
to cool.
Upon solidification, 27 grams of the mixture were
placed into a Carver laboratory press apparatus. The
solidified mixture was pressed at 3000 psi and 100C
for two hours in order to obtain an accelerated cure.
Alternatively, the solidified mixture may be pressed for
5 minutes at 3000 p5i and 100C and then allowed to cure
at room temperature for at least one week. The pressed,
cured product was of uniform thickness and was stamped
using a mallet and die to obtain samples for tensile
tests.
Tensile samples were tested at 23~C after 24-hour
storage at 23C and 50% humidity, and at 60C after
24-hour storage in 60C water (Table 3). The gel time
was determined to be that time at which the viscosity of
the polyamide/epoxy resin mixture reached a viscosity of
100,000 cps, as measured by a Brookfield RVTD viscometer
(Table 2).
Example 3: Comparative; Epoxy-Cured, Low Viscosity
Polyamide
An amine-terminated polyamide was produced by
combining the following ingredients in a resin kettle:
a polymerized fatty acid at 68.9 equivalent percent;
azelaic acid at 28 equivalent percent; stearic acid at
2.7 equivalent percent; ethylenediamine at 35 equivalent
percent; anhydrous piperazine at 57.2 equivalent
percent; diethylenetriamine at 10 equivalent percent;
and JeffamineTM D-2000 at 6.1 equivalent percent.
Antioxidants were added at 1.0 weight percent and about
6 drops of phosphoric acid catalyst were added.
A nitrogen inlet, baret trap, condenser, and
thermocouple were attached to the kettle head. This
system was stirred and heated gradually to approximately
250C for about three hours. Once most of the water had
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distilled over, the baret trap and condenser were
removed and vacuum was applied. The system was kept at
a constant temperature of about 250C under vacuum for
another three hours. The vacuum pressure was then
released and the polyamide was poured onto release paper
to cool.
The resulting polyamide had an acid number of 0.8
and an amine number of 10.7. The viscosity and
softening point of the uncured polyamide were determined
according to the method of Example 1 (Table 2). The
polyamide was treated and tested according to the
methods followed in Example 2 (Table 2 and Table 3).
Example 4: Epoxy-Cured Polyamide with Tallowamine
The procedure of Example 2 was followed, with the
exception that varying amounts of tallowamine (Kemamine
P-970~ were added to the polyamide prior to placing the
metal container into the pre-heated oven. Formulations
for samples 4(a) through 4(c) may be found in Table 1,
wherein the weight percents of the epoxy resin
(D.E.N. 439) and the tallowamine (Kemamine P-970) are
based on the weight of the polyamide resin. Gel times
may be found in Table 2, while the results of the
tensile testing are found in Table 3.
Example 5: Epoxy-Cured Polyamide with Tallowamine
and Tallowaminopropylamine
The procedure of Example 2 was followed, with the
exception that varying amounts of tallowamine (Kemamine
P-970) and tallowaminopropylamine (Kemamine D-999) were
added to the polyamide resin prior to placing the metal
container in the pre-heated oven. Formulations for
samples 5(a) and 5(b) may be found in Table 1, wherein
the weight percents of the epoxy resin (D.E.N. 439),
tallowaminopropylamine (Kemamine D-999), and tallowamine
(Kemamine P-970) are based on the weight of the
polyamide resin. Gel times may be found in Table 2,
while the results of the tensile testing are found in
Table 3.
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'`:
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Example 6: Epoxy-Cured Poly~mide with Ditallowamine
The procedure of Example 2 was followed, with the
exception that varying amounts of ditallowamine (Sherex
A-240) were added to the polyamide prior to placing the
metal container into the pre-heated oven. Formulations
for samples 6(a) through 6(c) may be found in Table 1,
wherein the weight percents of the epoxy resin
(D.E.N. 439~ and the ditallowamines (Sherex A-240) are
based on the weight of the polyamide resin. Gel times
may be found in Table 2, while the results of the
tensile testing are found in Table 3.
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TABLE 1
. .
FORMULATION
DEN 4391 p_s702 D-ggg3 A-2404
Example Polyamide (q)Wt. ~65 Wt. %5 Wt. %5 Wt. %5
506 __ __ ____
2 50 10---- ---- ----
3 507 10---- ---- --_
4(a) 506 13 5 __ __
4(b) 506 16 10 -- --
4(c) 506 19 15 ---- ----
5(a) 506 18.5 10 2.5 __
5(b) 506 21 10 5.0 --
6(a) 506 12 -- -- 5
6(b) 506 14 -- __ 10
6(c) 506 16 ---- ---- 15
1 D.E.N.TM 439 Epoxy Resin (Dow Chemical Co.,
Midland, MI)
2 KemamineTM P-970: Tallowamine (Humko Chemical Co.,
Memphis, TN)
3 KemamineTM D-999: Tallowaminopropylamine (Humko
Chemical Co., Memphis, TN)
4 SherexTM A-240: Ditallowamine (Sherex Chemical Co.,
Inc., Dublin, OH)
5 Weight % based on weight of polyamide.
6 UNI-REZIM 2636 (Union Camp Corp., Wayne,NJ)
7 Polyamide of Example 3.
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TABLE 2
Viscosity1Soft Pointl ~el Time2
Sample cps @ 190C C Minutes
1 7160 135 ---
2 7160 135 3.1
3 1200 132 2.0
4(a) 3750 130 2.2
4(b) 2155 126 3.1
4(c) 1280 127 2.6
5(a) 1870 126 2.8
5(b) 1450 126 2.2
6(a) 5040 134 6.1
6(b) 3030 132 6.2
6(c) 2360 133 6.4
_
Measurements taken prior to addition of epoxy curing
agent (D.E.N. 439).
2 Measurements taken after addition of epoxy curing agent
(D.E.N. 439).
2~518~
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2~18~
-18-
Example 7: Comparative; Epoxy-Cured Polyamide
Fifty grams of UNI-REZ 2636 were placed into a
metal container. The metal container was put into an
oven preheated to a temperature of 190C. The container
was removed when the polyamide became molten. Five
grams of epoxy resin (D.E~N. 438) were immediately and
thoroughly mixed into the polyamide. The resulting
molten mixture was poured onto release paper and allowed
to cool. Tensile tests were conducted according to the
1~ procedures of Example 2 (Table 4).
Example 8: Epoxy-Cured Polyamide with Tallowamine
The procedure of Example 7 was followed, with the
exception that 10% by weight (based on the polyamide) of
KemamineTM P-970 were added to the polyamide prior to
placing the metal container in the preheated oven.
Tensile test results may be found in Table 4.
Example 9: Epoxy-Cured Polya~ide with Ditallowamine
The procedure of Example 7 was followed, with the
exception that 10% by weight (based on the polyamide) of
SherexTM A-240 were added to the polyamide prior to
placing the metal container in the preheated oven.
Tensile test results may be found in Table 4.
Example lo: Epvxy-Cured Polyamide with Dimer/Diamine
The procedure of Example 7 was followed, with the
exception that 10% by weight (based on the polyamide) of
dimer/diamine were added to the polyamide prior to
placing the metal container in the preheated oven.
Tensile test results may be found in Table 4.
Example 11: Epoxy-Cured Polyamide with
Stearyl Stearamide
The procedure of Example 7 was followed, with the
exception that 10% by weight (based on the polyamide) of
KemamideTM S-180 (Humko Chemical Company, Memphis, TN)
were added to the polyamide prior to placing the metal
2~6~8~
container in the preheated oven. Tensile test results
may be found in Table 4.
Example 12: Epoxy-Cured Polyamide with
Stearyl Stearate
The procedure of Example 7 was followed, with the
exception that 10% by weight (based on the polyamide) of
Lexol-SSTM (Inolex Chemical Company, Philadelphia, PA)
were added to the polyamide prior to placing the metal
container in the preheated oven. Tensile test results
may be found in Table 4.
Example 13: Epoxy-Cured Polyamide with
Ethylene Bisstearamide
The procedure of Example 7 was followed, with the
exception that 10% by weight (based on the polyamide) of
KemamideTM W-40 (Humko Chemical Division, Memphis, TN)
were added to the polyamide prior to placing the metal
container in the preheated oven. Tensile test results
may be found in Table 4.
2 ~
- 20 --
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2~51~
-21-
E~ample 14: Vinyl T-Peel Tests
A vinyl peel test as described below was
performed on samples from Examples 1, 2, 3, 4(a) and
4(c). Vinyl strips were cut to a size of approximately
1.5 inches by 7 inches. A thin layer of the molten
polyamide/epoxy mixture covering an area of
approximately 1 inch by 6 inches was applied to one
warmed vinyl strip, using a typical draw-down bar. A
second warmed vinyl strip was then placed on top of the
molten adhesive layer and pressure was applied to the
bonded area by a hand roller, whereby the weight of the
roller itself supplied the pressure on the bonded area.
The adhesive was allowed to cure for one week, after
which time the vinyl strips were separated using an
apparatus capable of measuring the pressure required to
separate the bonded strips (Table 5).
Example 15: Lap Shear Strength
The samples prepared in Examples 1, 2 and
6(b) were tested for lap shear strength according to the
method described below.
The molten polyamide/epoxy mixtures were used
to bond different substrates having smooth surfaces,
including wood, polystyrene and polycarbonate. The
substrate samples were 1 inch wide by 4 inches long by
1/8 inch thick. The molten adhesive was placed on one
substrate surface which was at ambient temperature.
Another substrate was placed on top of the adhesive-
coated surface and pressed together by finger pressure
to give a bonded area of about 1 square inch. After
approximately 5 minutes, the substrates were flexed by
hand to determine if the bonded substrates exhibited
sufficient bond strength so as not to separate or slip.
All of the adhesive samples tested exhibited such bond
strength.
The samples were then allowed to set one week
at ambient temperature to complete cure. After cure was
2~6~18~
-22-
complete, one set of bonded substrates were placed in
room-temperature water to determine water resistance.
After soaking in water for one hour, the samples were
flexed by hand to determine bond strength as above. The
samples were replaced in the water and tested daily over
a one-week period for bond strength. Only sample 1
exhibited weakened bond strength as a result of
submersion in water.
Another set of samples were tested for lap
shear strength by separating the bonded substrates with
an apparatus capable of measuring the pressure required
to separate the bonded substrates (Table 6).
2~6~18~
-23-
TABLE 5
VINYL T-PEEL
Viscosity,1 Vinyl T-peel,
Sample cps @ 190C psi
1 716026.2
2 716042.3
3 120010.4
4(a) 375038.9
4(c~ 128032.2
Measurement taken prior to addition of epoxy curing
agent (D.E.N. 439).
TABLE 6
Lap Shear Strength
Sample Substrate Lap Shear, psi
1 Pine 341
2 Pine 354
6(b) Pine 537
1 Polystyrene76
2 Polystyrene165
6(b) Polystyrene136
1 Polycarbonate 188
2 Polycarbonate 281
6(b) Polycarbonate 236
:
