COPOLYAMIDE RESINS HAVING IMPROVED CREEP RESISTANCE

RESINES DE COPOLYAMIDES RESISTANT MIEUX AU FLUAGE

English Abstract

ABSTRACT OF THE DISCLOSURE
Copolyamides derived from a mixture of short-chain and long-chain
saturated aliphatic dicarboxylic acids, piperazine and a polyoxyalkylene
diamine are excellent hot melt adhesives useful with a variety of sub-
strates. These thermoplastic copolyamide resins are particularly useful
adhesives for vinyl materials especially plasticized vinyl substrates and
are resistant to creep.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A thermoplastic copolyamide adhesive resin having improved creep
resistance comprising the reaction product of essentially stoichiometric
amounts of:
(a) a mixture of saturated aliphatic dicarboxylic acids containing a
short-chain dicarboxylic acid having from 2 to 7 carbon atoms and
a long-chain dicarboxylic acid having from 8 to 14 carbon atoms;
(b) piperazine; and
(c) a polyoxyalkylene diamine of the general formula
<IMG>
where R is hydrogen or a methyl group and m is a positive integer
such that the average molecular weight of the polyoxyalkylene
diamine is between 200 and 800; the equivalents ratio of
the long- to short-chain dicarboxylic acids ranging from 0.5:0.5
to 0.9:0.1 and the equivalents ratio of the piperazine to polyoxy-
alkylene diamine ranging from 0.7:0.3 to 0.95:0.05.
2. The thermoplastic copolyamide adhesive resin of Claim 1 which
additionally contains up to 20%, based on equivalents, of an aliphatic, cyclo-
aliphatic or aromatic diamine having 2 to 10 carbon atoms, a dipiperidyl
type diamine selected from the group consisting of 1,3-di(4-piperidyl)propane,
1,4-di(4-piperidyl)butane and 1,2-di(4-piperidyl)ethane or an N-substituted
piperazine or dipiperidyl type diamine wherein the substituent is an amino-
alkyl or hydroxyalkyl radical having from 1 to 4 carbon atoms.
3. The thermoplastic copolyamide adhesive resin of Claim 1 which is
further characterized by having an acid value less than 10, an amine value
less than 20 and softening point in the range 100°C to 200°C.
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4. The thermoplastic copolyamide adhesive resin of Claim 3 wherein the
polyoxyalkylene diamine has an average molecular weight from 300 to 600 and
the equivalents ratio of piperazine to polyoxyalkylene diamine is between
0.75:0.25 and 0.90:0.10.
5. The thermoplastic copolyamide adhesive resin of Claim 4 wherein the
polyoxyalkylene diamine is a polyoxypropylene diamine, the long-chain
dicarboxylic acid has from 9 to 12 carbon atoms, the short-chain dicarboxylic
acid has from 4 to 6 carbon atoms and the equivalents ratio of long- to short-
chain dicarboxylic acids is between 0.65:0.35 and 0.80:0.20.
6. The thermoplastic copolyamide adhesive resin of Claim 5 which is
further characterized by having an acid value less than 7, amine value less
than 13 and softening point in the range 120°C to 170°C.
7. The thermoplastic copolyamide adhesive resin of Claim 5 wherein the
short-chain dicarboxylic acid is adipic acid and the long-chain dicarboxylic
acid is azelaic acid.
8. The thermoplastic copolyamide adhesive resin of Claim 7 which is
further characterized by having a softening point in the range 135°C to
155°C, 190°C viscosity in the range 125 poise to 300 poise, tensile strength
of 1400-1650 psi and elongation of 300-550%.
9. The thermoplastic copolyamide adhesive resin of Claim 5 wherein the
short-chain dicarboxylic acid is adipic acid and the long-chain dicarboxylic
acid is sebacic acid.
10. In a process for the preparation of thermoplastic copolyamide
adhesive resins by the reaction of essentially stoichiometric amounts of
-14-

(a) a mixture of adipic acid and a long-chain aliphatic saturated dicarboxylic
acid having 8 to 14 carbon atoms, (b) piperazine and (c) a polyoxyalkylene
diamine of the general formula
<IMG>
where R is hydrogen or a methyl group and m is a positive integer such that
the average molecular weight of the polyoxyalkylene diamine is between
200 and 800, the improvement which comprises heating the adipic acid, long-
chain aliphatic saturated dicarboxylic acid and polyoxyalkylene diamine at
160°C to 220°C with agitation under an inert atmosphere and adding piperazine
at a rate substantially to avoid polymeric salt formations.
11. The process of Claim 10 wherein the long-chain aliphatic saturated
dicarboxylic acid is azelaic acid or sebacic acid, the polyoxyalkylene
diamine is a polyoxypropylene diamine having an average molecular weight
from 300 to 600, the equivalents ratio of adipic acid to azelaic or sebacic
acid ranges from 0.5:0.5 to 0.9:0.1 and the equivalents ratio of piperazine
to polyoxypropylene diamine ranges from 0.7:0.3 to 0.95:0.5.
12. The process of Claim 11 wherein the piperazine is added as an
anhydrous melt.
13. The process of Claim 11 wherein the piperazine is added in an
aqueous solution.
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Description

1~99447
~nis invention rela~es to ther~oplas~ic copolyamide adhesive resins.
¦ Polyamides derived from polymeric fatty acids, e.~. dimer acid, are
well known and are highly useul a&esives for numerous applications with a
wide variety of substrates. For example, polyamides derived from polymeric
fatty acids and piperazine or dipiperidyl type diamines, and which optionally
contain other dibasic acids or diamines, are described in U. S. Patent
3,377,303. Ihese polyamide resins are useful for hot melt bonding vinyl
substrates. U. S. Patent 3,738,950 discloses adipic acid modified polyamide
resins derived from polymeric fatty acids and piperazine.
; ~here maximum vinyl a&esion is desired it is generally considered
advantageous to incorporate as high a level of piperazine as possible in
the polyamide without detracting from the other desirable characteristics
of the resin. The weight percentage of piperazine present in polymeric
fatty acid derived polyamides, however, is significantly less than it could
be if it were possible to employ short-chain dibasic acids in place of all
or a large portion of the polymeric fatty acid. It would bethighly
desirable therefore to prepare piperazine-containing thermoplastic polyamide
resins which are not derived from polymeric fatty acids but which exhibit
good overall characteristics making them suitable for hot melt bonding of -
various substrates. It would be even more advantageous if such resins
contained larger than usual amounts of piperazine so that improved vinyl
adhesion was obtained.
Ether diamines are also known to be useful reactants for the preparation
of polyamides. British Patent 1,319,807, for example, discloses copolyamide
resins derived from polymeric fatty acids and low molecular weight aliphatic
ether diamines. Similarly, U. S. Patent 2,499,853 discloses thermoplastic
adhesives derived from relatively low molecular weight ether diamines, by
themselves or in combination with ethylene diamine, and polymeric fatty acids.
_

9944~ `
More recently, the reaction of al:iphatic ether diamines with short-chain
aliphatic dicarboxylic acids has },een shown. German Offenlengungsschrift
25 52 518 discloses thermoplastic adhesive ccmpositions derived from a
polyoxypropylene p~lyamine and an aliphatic or aromatic dicarboxylic acid
hclving from 4 to 20 carkon atoms. German Offenlegungsschrift 25 52 455
further describes thermoplastic polyamide compositions which additionally
contain piperazine with the polyo~ypropylene polyamine and aliphatic or
aromatic dicarboxylic acid and indicates these resins are useful adhesives
particularly with epoxy materials.
It has now quite unex~pectedly been discovered that, by reacting
a mixture of ali-phatic dicarboxylic acids with piperazine and polyoxyaLky- ~
lene diamine, it is possible to obtain markedly improved thermoplastic co- r
polyamide adhesives useful for konding a variety of substrates. Ib obtain
these copolyamides very specific reactants must be employed within well de-
fined limits. me resinous products of aspects of this invention exhibit
superior adjesion to plasticized vinyl substrates. Quite unexpectedly the
copolyamide adhesives have marked resistance to creep.
By one aspect of this invention, a thermoplastic cop~lyamide
adhesive resin is provided having improved creep resistance comprising the
reaction product of essentially stoichiometric amounts of (a) a mixture of
saturated aliphatic dicarboxylic acids containing a short-chain dicarboxy-
lic acid having from 2 to 7 carbon atoms and a long-chain dicarbox~lic acid
having from 8 to 14 carbon atoms; tb) piperazine; and (c) a polyoxyalkylene
diamine of the general formula
CH3 I fH3
H2N-cHcH2~ocHcH2~mocH2cH-NH2
ere R is hydrogen or a methyl group and m is a positive integer such
that the average n~lecular weight of the polyoxyalkylene dic~l-Lne is between

200 and 800; the equivalents ratio of the long~ to short-chain dicarboxylic
acids ranging from 0.5:0.5 to 0.9:0.1 and the equivalents ratio of the
piperazine to polyoxyalkylene diamine ranging from 0.7:0.3 to 0.95:0.05.
By one variant thereof, the resin additionally contains up to 20%,
based on equivalents, of an aliphatic, cycloaliphatic or aromatic diamine
having 2 to 10 carbon atcms, a dipiperidyl type diamine selected from the
group consisting of 1,3-di(4-piperidyl~propane, 1,4-di~4-piperidyl)butane
and 1,2-di(4-piperidyl)ethane or an N-substituted piperazine or dipiperidyl
type diamine wherein the substituent is an aminoalkyl or hydroxyalkyl radi-
cal having from 1 to 4 carbon atoms.
By still another variant, the resin is further characterized byhaving an acid value less than 10, an amine value less than 20 and soften-
ing point in the range 100C to 200C.
By one variation thereof, the polyoxyaLkylene diamine has an
average molecular weight from 300 to 600 and the equivalents ratio of piper-
azine to polyoxyaLkylene diamine is between 0.75:0.25 and 0.90:0.10. t~
By another variation, the polyoxyalkylene diamine is a polyoxy-
propylene diamine, the long-chain dicarboxylic acid has from ~ to 12 carbon
atoms, the sh~rt-chain dicarboxylic acid has from 4 to 6 carbon atoms and
the equivalents ratio of long- to short-chain dicarboxylic acids is between
0.65;0.35 and 0.80:0.20.
By still another variation, the resin is further characterized by
having an acid value less than 7, amlne value less than 13 and softening
point in the range 120C to 170C.
By yet another variation, the short-chain dicarboxylic acid is
adipic acid and the long-chain dicarboxylic acid is azelaic acid.
By a further variation, the resin is further characterized by
having a softening point in the range 135C to 155C, 190C viscosity in
the range 125 poise to 300 poise, tensile strength of 1400-1650 psi and
elongation of 300-550%.
- 3 a -
.

,...... l~9g~4'7
By another variation, tJle short-chain dicarboxylic acid is adipic
acid and the long-chain dicarboxylic acid is sebacic acid. t
- By another aspec-t of this invention, an improvement is provided -
in a process for the preparation of thermoplastic copolyamide adhesive
resins by the reaction of essentially stoichiomieitric amounts of (a) a mix-
ture of adipic acid and a long-chain aliphatic saturated dicarboxylic acid
having 8 to 14 carbon atoms, (b~ piperazine and tc) a polyoxyalkylene dia-
mine of the general formula
CH, R CH3
H2~l--CH(,H2 (OCHCH2tmOCH2CH-NH2
where R is hydrogen or a methyl group and m is a positive intefer such that
theiaverage molecular weight of the polyoxyalkylene diamine is between 200 rand 800, the improvement which comprises heating the adipic acid, long-
chain aliphatic saturated dicarboxylic acid and polyoxyalkylene diamine at
160C to 220C with agitation under an inert atmosphere and adding pipera-
zine at a rate substantially to avoid polymeric salt formation.
By one variant thereof, the long-chain aliphatic saturated dicar-
boxylic acid is azelaic acid or sebacic acid, the polyoxyaLkyiene diamine ~.
is a polyo~ypropylene diamine having an average molecular weight from 300 to
600, the equivalents ratio of adipic acid to azelaic or sebacic acid ranges
from 0.5:0.5 to 0.9:0.1 and the equivalents ratio of piperazine to poly-
oxypropylene di D e ranges from 0.7:0.3 to 0.95:0.5.
By variants thereof, the piperazine may be added as an anhydrous
melt, or in an aqueous solution. ~ -
As referred to above, the copolyamide resins of one aspect of this ~ -
invention are generally obtained by the reaction of essentially stoichiome-
tric amounts of a mixed acid com~onent consisting of a mixture of a long-
chain saturated aliphatic di OE boxylic acid having from 8 to 14 car~on atQms
and a shorter-cham saturated aliphatic dicarboxylic acid having from 2 to
- - 3 b -

447
. .
to 7 carbon atoms with piperazine cmd polyoxyalkylene diamine having an
average molecular weight between 200 and 800. Especially useful adhesive
resins are obtained with short-chain dicarboxylic acids having from 4 to 6
carbon atoms and long-chain dicarboxylic acids having from 9 to 12 carbon
atoms. The equivalents ratio of long- to short-chain dicarboxylic acids
ranges from 0.5:0.5 to 0.9:0.1. Polyoxyprop~lene diamines of average mole-
cular weight 300 to 600 are preferred and the equi ~lents ratio of the pi- L
perazine to polyozyalkylene diamine will range from 0.7:0.3 to 0.95:0.05.
Up to 10% excess of acid or amine components can be employed for the pre-
paration of these copolyamides and small amounts of other aliphatic, cyclo-
aliphatic, or aromatic diamines or mixtures thereof included with the
piperazine and polyoxyalkylene diamine. he copolyamide resins have acid
values less than 10, amine values less than 20, softening points in the
range 120-170C and exhibit excellent resistance to creep.
The improved copolyamides of aspects of this invention are gener- S
ally derived from a mixture of long-chain and short-chain saturated ali- ~-
phatic dicarboxylic acids, piperazine and a polyoxyalkylene diamine. Op~
tionally, a small amount of other diamine may be present.
Necessarily present with the piperazine to form the amine camr
ponent is a polyoxyalkylene diamine corresponding to the general formNla
CH3 R CH3
., . H2N-CHCHz-~OCEICH23mOCH2C~NHz
where R is hydrogen or a methyl group and m is a positive integer such that
the average molecular weight of the polyoxyalkylene diamine is between 200
and 800. Especially useful polyoxyalkylene diamines for this invention
are polyoxypropylene diamines having average molecular weights from 300 to
600.
;~ :
.~ .
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lU994~7
~ e acid component is generally a ~xture of saturated aliphatic
dicarboxylic acids consisting of a short-chain dicarboxylic acid having
from 2 to 7 carbon atoms and a longer-chain dicarboxylic acid having from 8
to 14 carbon atoms. This acid mixture is essential to obtain the improved
creep-resistant copolyamide compositions of aspects of this invention.
Especially useful short-chain i-
L
.:
- 4 a -
- ~ :
.. . ~ .

999L~
dicarboxylic acids will have 4 to 6 carbon atoms and include succinic,
glutaric and adipic acids. The longer-chain saturated acids will preferably
have 9 to 12 carbon atoms with azelaic acid and sebacic acid being
S especially useful. By reacting the acid mixture, wherein the short-chain
and long-chain dicarboxylic acids are present in specified ratios, with the
piperazine and polyoxyalkylene diamine it is possible to obtain superior
copolyamide adhesive resins which exhibit little or no plastic creep.
Essentially stoichometric amounts of the mixed acid component and the
amine component consisting of piperazine and the polyoxyalkylene diamine
are reacted to obtain these thermoplastic copolyamide resins. Not more than
a 10% excess of either the acid or amine component should be present for the
reaction and typically if an excess is to be employed it is preferable that
the amine component be present in excess.
Generally the combination of adipic acid and piperazine~in a homopolymer
or copolymer system at low to moderate temperatures of 20C to 160C
will result in the formation of high-melting adipic-piperazine polymeric
salt which is quite difficult to satisfactorily transform into the polyamide -
or copolyamide by elimination of water. If these conditions are used, low
molecular weight polyamide segments and incompletely transformed polymeric
organic salt ~that is present as an insoluble or incompatible suspension)
will be obtained so as to detract from the appearance and the utility of
the final pro,duct. To avoid this problem and still utilize adipic acid with
.perazine, it has been found that techniques which limit the formation of the
I ~, .
polymeric adipic-piperazine salt could be developed by restricting the
concentration of piperazine or adipic acid during amidation. This is
accomplished by introducing anhydrous or~ aqueous piperazine slowly to the
hot (160-220C) mixture containing adipic acid so as to avoid the immediate
f~4~tion o :he pcl ~ ric salt ~hile rapi~ly decomp ~in~ the ca- cx~l-rich

~ 1~994~7
salt system to form amide. By use of this technique no polymerie salt that
resists amide formation will occur and little if anyloss~of adipic aeid
is seen. The reverse of this proceS~ slow addition of molten or aqueous
solutions of adipic acid to a hot (160-220C) amino-termunated prepolymer o~
azelaic or other dibasic acids and piperazine with or without other diamines
has been found to yield similar results but is less desirable because of the
tendency of anhydrous molten adipic acid to degrade and the larger volumes
of water needed to prepare aqueous adipie aeid solutions.
The acid and aminecomponents are then reacted at maximum temperatures
up to ;~240C until the desired acid and amine values are aehieved. It
usually requires several hours to complete the reaction whieh is eonveniently
followed by measuring the amount of water evolved. The reaction is
preferably conducted under an inert atmosphere, e-g- nitrogen, and during
the final stages of the reaction a vacuum may be applied to facilitate
removai of the final traces of water and other volatiles present in the
system.
he ratio of the long-chain dicarboxylic acid to short-chain dicarboxylic
acid will range fro~ 0.5:0.5 to 0.9:0.1 based on equivalents. The
equivalents ratio of piperazine to polyoxyalkylene diamine will range from
0.7:0.3 to 0.95:0.05. Superior resins which are especially
useful for adhesion of vinyl substrates and which exhibit little or no
plastic creep are obtained when the equivalents ratio of long- to short-
chain acid is between 0.65:0.35 and 0.80:0.20 and the equivalents
ratio of the piperazine to polyoxyalkylene diamine is between 0.75:0.25 and
0-90:0.10.
:
Aliphatie, eycloaliphatic or aromatic diamines containing up to
20 carbon atoms and more preferably from 2 to 10 carbon atoms e.g.
, I _ . . .

9944~7
ethylenediamine, hexamethylenedialnine, xylenedia~une, bis(aminoethyl)
benzene, methylene-or isopro~ylid~ne-biscyclohexylamine, 1,4-piperazine- i~
bispropylamine and the like can be employed at low levels. Also useful are
dipiperidyl type diamines e.g. 1,3-di(4-piperidyl)prppane, 1.4-di(4-piperi-
dyl)butane and 1,2-di(4-piperidyl)ethane and N-substituted piperazine or
dipiperidyl type diamines wherein the substituent consists of an aminoalkyl
or hydroxyal~yl radical containing from 1 to 4 carbon atoms e.g. N-amino- r
ethylpiperazine, N-aminopropylpiperazine and the like. While these dia-
mines may constitute up to 20%, based on equivalents, of the total amine
component they are typically present in amounts not greater than 10%.
The resins of aspects of this invention, formed from the above- r
described reactants in the defined ratios, typically have an acid value ~! '
(A.O.C.S. Method Te la-64) less than 10 and amine value (ASTM Method D2074-
66~ v~lue less than 20. Preferably the acid value of the resin will be less
than 7 and amine value less than 13. ~hile the softening point (ASTM
Method E-28) can range from 100C to 200C it is preferable for most appli-
cations that the softening point fall between 120 and 170C. In an especi-
ally preferred e~bodiment of an aspect of this invention, w~ere the mixed
acid ccmponent oonsisting of a mixture of azelaic acid and adipic acid
(equivalents ratio of 0.65-0.75:00.35-).25) is reacted with 0.80 to 0.95
equivalent piperazine and 0.15 to 0.25 equivalent polyoxypropylene diamine
having an average molecular weight of 350-450, a copolyamide having excel-
lent vinyl adjesion and resistant to plastic creep and having the following
general specification is obtained:
Softening Point (C) 135-155
190C Viscosity (poise) 125-300
TensiIe Strength (psi) 1400-1650
Elongation (%) 300-550
-- 7 --

- 1(399~7
It has already been indicated tha~- one of the highly desirable features of
the present copolyamides of aspec-~s of this invention which is quite unex~ f
pected is their resistance to plastic creep. While other polyamide resins
derived from piperazine and polyoxyalkylene diamines exhibi-t good adhesive
properties it is onlv with the use of the muxed aliphatic dicarboxylic acid
component with the piperazine and polyoxyalkylene diam me in the prescribed
ratios that resins which exhibit little or no plastic creep can be obtained.
miS feature is highly desirable for many hot melt adjesive applications,
particularly with difficulty bondable plasticized vinyl resin compositions,
since it assures a permanent and fixed arrangement of the bonded assembly.
In other words the bonded materials retain the same relative position so ~;
long as the assembly is not exposed to temperatures near or akove the melt
point or softening point of the resin.
~le copolyamide resins of aspects of this invention are ~seful as
hot melt adllesives with a wide varietv of substrates. They can be used as
such with both rigid or flexible, natural or synthetic, materials and are
particularly useful for bonding vinyl materials. They may be employed to
adhere leather, suede, and both woven and non-w~ven fabrics obtained from
cotton, wool, silk, sisal, hemp, jute, rayon ~nd synthetic fibers, e.g.,
nylons, acrylics, polyesters, polyolefins and the like. They are also use-
ful with natural rubber, polyurethanes, neoprene, styrene-butadiene copoly-
mers, polybutadiene, AES and other polymeric materials. The present resin
compositions are similarly useful for hot melt bonding rigid materials, e.g.
metals, including aluminum, steel, etc., wood, paper products, phenolics,
cork, pressboard, glass and the like. The copolyamide resins are applied
using conventional hot melt application proceduresj e.g. spraying, printing, ~-
dipping, spreading, rolling, an~ the like and the film thickness can range
from less than one mil up to fifty mils. While for most oonstructions the
resin is applied to only one side of the substrate it may be applied to
both sides in order to form a sandwich-type construction. me copolyamides
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.
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:

1~\99447
o~_asp~ects of this invention may be also
be blended with other polyamide and polyester adhesive resins to obtain a
wide variety of additional compositions useful for hot melt bonding. The
present copolyamides may constitute as little as 0.5 weight percent of the
total resins or, if other resins or additives are added thereto, can
constitute as much as 99.9 weight percent of the total composition.
The invention is more fully illustrated by the following examples. All
parts and percentages in these examples are on a weight basis unless otherwise
indicated.
E~AMPLE I
Azelaic acid, adipic acid, piperazine and a polyoxypropylene diamine
having an average molecular weight of 400 were reacted to obtain a
copolyamide adhesive resin. The reactant charge was as follows:
Parts ,
Azelaic Acid 105
Adipic Acid 27
Piperazine 57
Polyoxypropylene Diamine 59
. .
The ratioof equivalents (azelaic acid:adipic acid:piperazine:polyoxyal~ylene
diamine) for the above charge was 0.7:0.25:0.88:0.20. Azelaic and adipic
acid and polyoxypropylene diamine were first charged to the reactor and
heated under a nitrogen atmosphere to about 200-210C. Piperazine dissolved
in hot water (60~ aqueous solution) was then added slowly but at a steady
rate with agitation so that foam-over was avoided and the temperature did
not drop below 200C. When the addition was complete the reaction was
continued and the temperature increased to 220C. After the bulk of
the theoretical amount of water was collected a vacuum of 5 Torr was

1~9~447
applied to remove the final traces of water. The resulting copolyamide resin
(acid value <3 and amine value <20) had the following properties: 190C
viscosity (Brookfield Thermosel) 200 poise, softening point of 145C,
Gardner color 3; tensile strength 1500 psi; and elongation at break 450~.
The above-prepared thermoplastic oopolyamide resin was used to bond a
variety of substrates. Various materials were bonded and the shear strength
of the resulting bond determined in accordance with ASTM Test Procedure
D 1002-72. The results obtained were as follows:
MaterialShear Strength (psi)
i Aluminum 1280
Steel 1570
Wood 500
Phenolic Resin 550*
ABS Resin 90
*Designates failure of substrate.
~ : ~
The adhesive resins were also evaluated in accordance with ASTM Test
Procedure D 1876-72 to determine the peel or stripping strength of various
adhesive bonds. Cotton duck, fabric-backed vinyland an unsupported vinyl/ABS -
blend were employed for this test. The peel strengths observed for theserespective materlals were 18 lbs./in., 15 lbs./in. and 20 lbs./in. In all
instances substrate failure occurred before failure of the adhesive bond.
Additionally, resistance to plastic creep of the adhesive resin was
determined by bonding three inches of a 1" x 5" strip of the unsupported
vinyl/ABS material to a 6" x 6" piece of pressboard. The bonded assembly
was then placed in a 70C oven in an inverted horizontal position with a
100 gram weight attached to the 2" unbonded "tail". The extent of delamina-
tion over a four hour period was observed. If 2 1/2" or more is pulled away
-10- .
l ,,,,__

1-~99447
from the pressboard in four hour-; or :Less this is considered to be a failure.
Anything less than 2 1/2" after four hours is acceptable. The less
delamination the better the creep resistance of the adhesive resin. When
the copolyamide of this example was evaluated for plastic creep no delamina-
tion was obtained after the four hour test period.
In another procedure to evaluate resistance to creep 1" steel strips
are bonded with a 1/2" lap joint. The assembly is hung in an oven with a
one pound weight suspended from the bottom. The temperature is increased
at a rate of 5C/30 minutes until the bond fails. The copolyamide
of;this example withstood a temperature of 130C before failure.
EXAMPLE II
To demonstrate the unexpected improvement in creep resistance obtained
when mixed saturated aliphatic dicarboxylic acids are employed with piperazin
and the polyoxypropylene diamine (M. W. 400) the following reactions were
conducted. For this example two copolyamides were prepared.~ In the first
experiment (A) a mixture of adipic acid and azelaic acid was used whereas
for the second reaction (B) azelaic was the sole dicarboxylic acid. ~he
equivalents ratio of reactants and the properties of the resulting adhesive
resins were as follows:
A B
Azelaic Acid 0.8 1.0 -
Adipic Acid 0.2 ---
Piperazine 0.85 0.85
Polyoxypropylene Diamine 0.15 0.15
Acid VaLue 9.5 6.2
Amine Value 11.3 10.0
Sofiening Point (C) 126-139 130-133
~ . _ . .

1~99447
Both copolyamides exhibited good adhesion to vinyl and other substrates
¦¦ including leather, me-tal and w~od. ~lowever, copolyamide ~, the product of
¦¦ an aspect of this invention, also exhibited superior creep resistance.
~is product
did not fail the plastic creep test even after 72 hours at 70C. On the
other hand, Product s failed the plastic creep test within 15 minutes at
70C. The above data ~learly demonstrates the superiority of the products
of aspects of this inv~ ~ion.
EXAMPLES III - V
To demonstrate the ability to vary the ratio of reactants the following
experiments were conducted. The table sets forth the equivalents ratio of
the reactants and the properties of the resulting copolyamide resin:
Ex. III Ex. IV Ex. V
Azelaic Acid 0.5 0.75 0.7
Adipic Acid 0.5 0.25 0.3
Piperazine 0.8 0.8 0.85
Polyoxypropylene Diamine 0.2 0.2 0.15
(M. W. 400)
Acid Value 4 3.2 4
Amine Value 15 9.1 11
Softening Point tC) 212 147-162 170-175
Vinyl Adhesion Excellent Excellent Excellent
Plastic Creep (in.) 0 0 0
While all the resins passed the plastic creep test, the resins of Example IV
did not fail even after 72 hours at 70C.
Similar results are obtained when pimelic acid is substituted for adipic
acid, when sebacic acid ordodecanedioic acid is substituted for azelaic acid
andwhen a polyoxypropylene diamine having an average molecular weight of
230 is substituted for the 400 molecular weight material.
-1-
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