THERMOSETTING RESIN SYSTEMS CONTAINING SECONDARY AMINE-TERMINATED SILOXANE MODIFIERS

SYSTEMES DE RESINE THERMODURCISSABLE CONTENANT DES MODIFICATEURS DE SILOXANES BLOQUES PAR DES AMINES SECONDAIRES

English Abstract

THERMOSETTING RESIN SYSTEMS CONTAINING
SECONDARY AMINE-TERMINATED SILOXANE MODIFIERS
Abstract of the Disclosure
Modified heat-curable resins having enhanced tough-
ness are prepared through incorporation of certain secondary
amine terminated organosilicones or prereacts of these organo-
silicones with epoxy, cyanate, or bismaleimide resins. These
modified resins are useful as toughened matrix resins, as high
temperature, high strength elastomers, and, particularly, as
structural adhesives.
-47-

Claims

The embodiments of the invention in which an exclu-
sive property or privilege is claimed are defined as follows:
1. A process for the preparation of a secondary
amine-functionalized organosilicone comprising reacting
a) an N-substituted-N-alkenylmonoamine selected from
the group consisting of N-aryl-N-alkenyl amines,
N-alkyl-N-alkenylamines, N-cycloalkyl-N-alkenyl
amines, and N-aralkyl-N-alkenyl amines, wherein
the ethylenic unsaturation of said alkenyl amine
is located at least two carbon atoms away from the
amino nitrogen with:
b) an Si-H functional organosilicone selected from
the group consisting of
<IMG> and <IMG>
where each R1 is selected from the group con-
sisting of hydrogen; alkyl; alkoxy; cyanoalkyl;
halogenated alkyl; acetoxy; and substituted and
unsubstituted cycloalkyl, aryl, and araalkyl; and
-35-

<IMG>
wherein m is a natural number from 1 to 10,000 and
n is a natural number from 0 to about 10,000;
wherein p is a natural number from 2 to about 20;
wherein the sum m+n is less than about 10,000; and
wherein at least one R1 is hydrogen; in the
presence of,
c) a hydrosilation reaction-promoting-catalyst
present in an amount effective to catalyze the
reaction between (a) and (b).
2. The process of claim 1 wherein said organosili-
cone is selected from the group consisting of:
<IMG> and
<IMG>
-36-

where q is an integer from 2 to about 100.
3. The process of claim 2 wherein said catalyst is
selected from the group consisting of hexafluoroplatinic acid
and hexachloroplatinic acid and the hydrates and salts thereof.
4. The process of claim 2 wherein each R1 is
individually selected from the group consisting of hydrogen,
methyl, ethyl, and phenyl.
5. The process of claim 2 wherein said organosili-
cone is selected from the group consisting of tetramethyldi-
siloxane, tetraphenyldisiloxane, and 1,3-dimethyl-1,3-diphenyl-
disiloxane.
6. The process of claim 2 wherein said organosili-
cone is an Si-H terminated cogeneric polydimethylsiloxane
corresponding to the formula:
<IMG>
wherein q is an integer from about 1 to about 10,000.
7. The process of claim 1 wherein said N-
substituted-N-alkenyl monoamine is an N-substituted-N-allyl
monoamine.
-37-

8. A process for the preparation of an N-
substituted, secondary .omega.-aminoalkyl organosilicone polymer,
comprising:
a) preparing an N-substituted, secondary .omega.-aminoalkyl
functionalized organosilicone having the formula:
<IMG>
by the process of claim 1, wherein R1 is individu-
ally selected from the group consisting of alkyl,
alkoxy; cycloalkyl, halogenated alkyl; acetoxy;
and substituted and unsubstituted cycloalkyl,
aryl, and araalkyl;
<IMG> ;
and
<IMG>
wherein k is an integer frm 3 to about 5;
-38-

consisting of acetoxy, alkyl, alkoxy, cyanoalkyl,
halogenated alkyl, cycloalkyl, aryl, and aralkyl
radicals; in the presence of
c) an effective amount of polysiloxane equilibration-
polymerization catalyst,
to form a higher molecular weight N-substituted, secondary .omega.-
aminoalkyl organosilicone.
9. The process of claim 8 wherein said N-
substituted, secondary .omega.-aminoalkyl functionalized organo-
silicone is an N-substituted, secondary 3-aminopropyl func-
tionalized organosilicone.
10. The process of claim 9 wherein said cyclosiloxane
is selected from the group consisting of octamethylcyclotetra-
siloxane, octaphenylcyclotetrasiloxane, 1,2,3,4 tetramethyl-
1,2,3,4-tetraphenylcyclotetrasiloxane, hexamethylcyclotri-
siloxane, hexaphenylcyclotrisiloxane, and 1,2,3-trimethyl-
1,2,3-triphenylcyclotrisiloxane.
11. The process of claim 9 wherein said cyclosiloxane
is selected from the group consisting of octamethylcyclotetra-
siloxane and octaphenylcyclotetrasiloxane.
12. The process of claim 9 wherein said polymer-
ization catalyst is selected from the group consisting of the
alkali metal silanolates and siloxanolates; the tetrakis-
(alkyl)ammonium silanolates and siloxanolates; tetrakis-
-39-

wherein n is a natural number from 1 to about 10,000;
wherein m is a natural number from 0 to about 10,000;
wherein the sum m+n is less than about 10,000; and
wherein at least one R1 is
<IMG>
wherein R is selected from the group consisting of
substituted and unsubstituted alkyl, cycloalkyl, aryl
and araalkyl radicals carrying no primary amino
groups;
b) reacting the bis(N-substituted, secondary 1-
aminoalkyl)siloxane (a) with one or more persub-
stituted cyclosiloxanes having the formula:
<IMG>
wherein r is an integer from 1 to about 10,
and R3 is selected individually from the group
-40-

(alkyl)phosphonium silanolates and siloxanolates; tetrakis-
(alkyl)phosphonium hydroxides; and the tetrakis(alkyl)ammonium
hydroxides.
13. The process of claim 9 wherein said polymer-
ization catalyst is selected from the group consisting of
tetramethylammonium hydroxide and tetramethylammonium siloxano-
late.
14. A process for toughening a heat-curable resin
system, comprising adding thereto a toughening amount of an
organosilicone toughener selected from the group consisting of
a)
<IMG>
wherein R1 is individually selected from the group
consisting of alkyl, alkoxy; cycloalkyl, halogenated
alkyl; acetoxy; and substituted and unsubstituted
cycloalkyl, aryl, and aralkyl;
<IMG> ; and
<IMG>
-41-

wherein k is an integer from 3 to about 5;
wherein n is a natural number from 0 to about
10,000; wherein m is a natural number from 1 to
about 10,000; wherein the sum m+n is less than
about 10,000; and wherein at least one R1 is
<IMG>
wherein R is selected from the group consisting of
substituted and unsubstituted alkyl, cycloalkyl,
aryl and araalkyl radicals carrying no primary
amino groups;
b) a prereact comprising the reaction product of a)
with a resin reactive therewith, said resin
selected from the group consisting of epoxy,
cyanate, and bismaleimide resins and mixtures
thereof; and
c) mixtures of a) and b).
15. The process of claim 14 wherein said heat-curable
resin system is selected from the group consisting of:
a) epoxy resin systems,
b) cyanate resin systems,
-42-

c) bismaleimide resin systems, and
d) mixtures thereof.
16. The process of claim 15 wherein each R1 is
individually selected from the group consisting of methyl
radicals, phenyl radicals, and
<IMG> radicals.
17. The process of claim 15 wherein said heat-curable
resin system is an adhesive.
18. A heat-curable resin composition, comprising
a) a heat-curable resin system, and
b) a silicone modifier selected from the group
consisting of
i) secondary amine-functionalized organosilicones
having the formula
<IMG>
wherein R1 is individually selected from the group
consisting of alkyl, alkoxy; cycloalkyl,
-43-

halogenated alkyl; acetoxy; and substituted and
unsubstituted cycloalkyl, aryl, and aralkyl;
<IMG> ; and
<IMG>
wherein k is an integer from 3 to about 5;
wherein n is a natural number from 0 to about
10,000; wherein m is a natural number from 1 to
about 10,000; wherein the sum m+n is less than
about 10,000; and wherein at least one R1 is
<IMG>
wherein R is selected from the group consisting of
substituted and unsubstituted alkyl, cycloalkyl,
aryl and aralkyl radicals carrying no primary
amino groups;
-44-

ii) a prereact prepared by reacting the
secondary amine-functionalized organo-silicone of
5)b)i) with a resin reactive therewith, said resin
selected from the group consisting of epoxy
resins, cyanate resins, bismaleimide resins, and
iii) mixtures thereof.
19. The composition of claim 18 wherein said heat-
curable resin system is selected from the group consisting of
a) epoxy resin systems,
b) cyanate resin systems,
c) maleimide-group-containing resin systems, and
d) mixtures thereof.
20. The composition of claim 19 wherein each R1 is
individually selected from the group consisting of methyl
radicals, phenyl radicals, and
<IMG> radicals.
21. The heat-curable resin composition of claim 19
wherein said composition is an adhesive.
22. The heat-curable resin composition of claim 18
further comprising from 40 to about 90 percent by weight,
relative to the weight of the total composition, of reinforce-
-45-

ment selected from the group consisting of woven and nonwoven
yarn, tape, and cloth comprising fiberglass, carbon/graphite,
boron, or thermoplastic fiber wherein said reinforcement
contributes substantially to the strength of the cured composi-
tion.
23. The composition of claim 22 wherein said thermo-
plastic reiinforcement is selected from the group consisting of
high modulus polyolefin, aramid, polyetherketone, polyether-
etherketone, polyetherketoneketone, polyethersulfone,
polyphenylenesulfide, polyketonesulfone, and
polyetherketonesulfone.
24. The composition of claim 22 wherein said thermo-
plastic has a glass transition temperature Tg above 150°C.
25. The heat-curable resin composition of claim 18,
further comprising from 1 to about 25 percent by weight,
relative to the weight of the total composition, of support
selected from the group consisting of woven and nonwoven yarn,
tape, and cloth comprising fiberglass, carbon/graphite, boron,
or thermoplastic fiber wherein said support does not contribute
substantially to the strength of the cured composition.
-46-

Description

iZ964fi6 ~506
~HE~MOSETTING RESIN SYSTEMS CONTAINING
SECONDARY AMINE-TERMINATED SILOXANE MODIFIERS
Background of the Invention
1. Field of the Invention
The subject invention relates to thermosetting
resin systems which contain certain secondary amine-terminated
siloxane modifiers. The modified resins find uses as heat-
curable matrix resins in fiber-reinforced prepregs, as lam-
inating films, and as structural adhesives.
2. Description of the Related Art
Modern high-performance thermosetting resin systems
contain a variety of heat-curable resins. Among these are
epoxy resins, maleimide-group-containing resins, and the
cyanate resins. All these resins are noted for their high
tensile and compressive strenqths and their ability to retaln
these properties at elevated temperatures, and all find
extensive use in the aerospace and transportation industries.
Other thermosetting systems which may be useful at lower
temperatures or for specific applications include the
polyurethanes, polyureas, polyacrylics, and unsaturated
polyesters.

129~i4fi6
Unfortunately, many of these resin systems tend to be
brittle. Thus while exhibiting high strengths under constant
or slowly changing stress/strain, these systems and the
structures which contain them may be susceptible to impact-
induced damage. It would be desirable to prepare matrix resin
and adhesive formulations which maintain their high strength
properties while having enhanced toughness.
In the past, functionalized elastomers such as the
amino- or carboxy-terminated butadiene-acrylonitrile copolymers
(ATBN and CTBN, respectively) available from B.F. Goodrich
Corp. under the trademark HYCAR0 have been used with some
degree of success in toughening both adhesive and matrix resin
formulations. See, for example, the article by J. Riffle,
et. al., entitled "Elastomeric Polysiloxane Modifiers" in
E~oxy Resin Chemistrv II, R. Bauer, Ed., ACS Symposium Series
No. 221, American Chemical Society, and the references cited
therein.
The use of ATBN elastomers having carbon backbones,
while increasing toughness, does not provide sufficient thermal
and/or oxidative stability for many modern applicationæ of
adhesives and matrix resins, particularly those in the aero-
space field. Thus it has been proposed to utilize functional-
ized polysiloxanes for these applications, relying on the
thermal-oxidative stability of the silicon-containing backbone
--2--

~Z96~fi~
to lend increased thermal stability to the total resin
system. Several such approaches have been discussed in Riffel,
supra, and involve primary amine terminated polysiloxanes such
as bis(3-aminopropyl)polysiloxanes and secondary amine
terminated polysiloxanes such as bis(piperazinyl)polysiloxanes.
Perhaps due to their lower functionality, the
secondary amine terminated, piperazinyl polysiloxanes generally
proved to have superior physical properties compared to the
primary amine terminated polysiloxanes (tetrafunctional).
Unfortunately, these secondary amine terminated polysiloxanes
are difficult to prepare.
One preparation of piperazinyl functionalized
polysiloxanes involves reaction of 2-aminoethylpiperazine with
a previously synthesized carboxy-terminated polysiloxane to
form the bis(2-piperazinyl ethyl amide) of the polysiloxane:
_ "
H- ~ N-CH2CH2-NH-C - - polysiloxanediyl
A second approach is to react a large excess ~to
avoid polymer formation) of piperazine with a bis-epoxy
polysiloxane, producing a bis(2-hydroxy-3-piperazinyl) poly-
siloxane:

~296~fi6
o~
H ~ -CH2-CH-CH2- - polysiloxanediyl.
-
This method, of course, requires prior preparation of theepoxy-functional polysiloxane.
Ryang, in ~.S. Patent 4,511,701, prepared both
primary and secondary amine-terminated polysiloxanes by
reacting an appropriately substituted diamine with difunctional
silylnorbornane anhydrides, themselves prepared as disclosed by
Ryang in U.S. Patent 4,381,396. Reaction of these diamines
with the bis(anhydride) functional polysiloxanes results in
amino-imides such as:
[Hl-R'-N \~ ~ polysiloxanediyl
Only the last-mentioned process produces amino-
functional polysiloxanes which are truly difunctional. The
amide hydrogen and hydroxyl hydrogen produced by the first two
preparations, though less reactive than the secondary amino
hydrogens, are nevertheless reactive species in most resin
systems. Their presence, therefore can cause further, and at
times unpredictable crosslinking, either over an extended
period of time in normal service, or as a result of high curing
temperatures.
--4--

129~4fi6
Furthermore, all of the foregoing preparations
involve many steps, and in the process consume large quantities
of relatively expensive chemical reagents. All these prior art
products are difficult to prepare, expensive products, and thus
there remains a need for thermally stable, secondary amine
terminated polysiloxanes which may be prepared in high yield
and in an economic manner.
SummarY of the Invention
It has now been found that the use of certain
secondary amine-functionalized organosilicones may be used to
modify a wide variety of thermosetting resin systems. These
secondary amine-functionalized organosilicones may be used as
reactive modifiers in any resin system which contains chemical
groups which are reactive towards secondary amino groups.
Alternatively, the secondary amine-functionalized organosili-
cones may be prereacted with a monomeric, oligomeric, or
polymeric reagent to form a "prereact" which is compatible but
not necessarily reactive with the primary resin. Such modified
resins display considerably enhanced toughness while main-
taining their elevated temperature performance. Adhesives
formulated with such modifiers show surprisingly enhanced lap
shear strengths.

1296~fi6
~ hese modifiers may be readily prepared in quanti-
tative or nearly quantitative yields, by reacting a secondary
N-allylamine corresponding to the formula:
/ CH2CH CH2 '
or an analogous secondary N-ly-butenyl)- or N-l~-pentenyl)amine
with an Si-H functional organosilicone, preferably a 1,1,3,3-
tetrasubstituted disiloxane or silane functional persubstituted
polysiloxane, in the presence of a suitable catalyst. In the
disclosure which follows, references to the reaction of
secondary N-allylamines should be taken to include, where
appropriate, the corresponding reaction of secondary-N-(~-
butenyl)amines and secondary-N-(~-pentenyl)amines. Higher
molecular weight polysiloxanes may be prepared by the equilib-
rium polymerization of the product of the above reaction with
additional siloxane monomer to form secondary amine-functional-
ized homopolymers of higher molecular weight, or block or
heteric organosilicones which correspond to the general formula
Rl Rl
Rl-Si~O-Si~LR
R Rl m
wherein each Rl may be individually selected from the group
-6-

lZ96~6
consisting of alkyl, preferably Cl-C12 lower alkyl; alkoxy,
preferably Cl-C12 lower alkoxy; acetoxy; cyanoalkyl; halogen-
ated alkyl; and substituted or unsubstituted cycloalkyl, aryl,
and aralkyl;
Ht-( CH2 ) k
R
wherein k is an integer from 3 to about 5, preferably
HN
R
and X, wherein X is selected from the group consisting of
Rl
~O-Ii~Y
L RlJ n
wherein ~ is selected from the group consisting of alkyl,
preferably Cl-C12 lower alkyl; alkoxy, preferably Cl-C12 lower
alkoxy; acetoxy; cyanoalkyl; halogenated alkyl; cycloalkyl;
aryl; and aralkyl; wherein m is a natural number from O to
about 10,000, preferably from 1 to about 500; wherein n is a
natural number such that the sum of m+n is from about O to
--7--

12964fi6
10,000, preferably from 1 to about 1000, and more preferably
from 1 to about 500; and wherein at least one of Rl, ~, or Y is
HN~CH~k
wherein k is an integer from 3 to about 5. Most preferably,
the secondary amino functional organosilicones are bislsec-
ondary ~-amino-functionalized] organosilicones which correspond
to the formula
Rl Rl
7VI --E I i~VNH,
R R R m R
where R may be a substituted or unsubstituted alkyl, cyclo-
alkyl, aryl, or aralkyl group which does not carry a primary
amino group, and where each Rl may be individually selected
from cyano, alkyl halogenated alkyl, preferably Cl-C12 lower
alkyl, alkoxy, preferably Cl-C12 lower alkoxy, acetoxy,
cycloalkyl, aryl, or aralkyl groups, and wherein m i8 an
integer from O to about 10,000, preferably 1 to about 500.
As indicated, the Rl substituents may be the same as
each other, or may be different. The phrase "may be individu-
-8-

~296~fi6
ally selected," or similar language as used herein, indicates
that individual Rls may be the same or different from other Rl
groups attached to the same silicon atom, or from other Rl
groups in the total molecule. Furthermore, the carbon chain of
the w-aminoalkylene-functional organosilicone may be
substituted by inert groups such as alkyl, cycloalkyl, aryl,
arylalkyl, and alkoxy groups. References to secondary amino-
propyl, aminobutyl, and aminopentyl groups include such
substituted ~-aminoalkyl groups.
In addition to the preferred bis(N-substituted,
secondary aminopropyl)polysiloxanes, tris- or higher analogues
may also be prepared by the subject process if branched or
multi-functional siloxanes are utilized. Such higher func-
tionality secondary amino-functionalized siloxanes, for
example, may be useful as curing agents with resins of lesser
functionality. Monofunctional N-substituted, secondary 4-
aminobutyl-, 5-aminopentyl, and 3-aminopropylsiloxanes may also
be prepared. Such monofunctional siloxanes have uses as
reactive modifiers in many polymer systems.
DescriDtion of the Preferred Embodiments
The secondary-amine-functional organosilicone
modifiers of the subject invention may be prepared through the
reaction of an N-allyl secondary amine with an Si-H functional
organosilicone. In the discussion which follows, references to
_g _

lZ969~fi6
organosilicone reactants, in general, are intended to include
silanes and di- and polysiloxanes which have Si-H function-
ality. The preferred reaction may be illustrated as follows:
Rl Rl Rl Rl
HN ~ I Rl R li-O-Si V NH
Of course, by varying the nature of the Si-H func-
tional organosilicone, a variety of products may be obtained.
For example, a polysiloxane having one or more pendant sec-
ondary amino functionalities may be prepared readily from an
Si-H functional cyclic siloxane:
Me
I. I H-S~
rO IMel
HN~Sl-Me L I ~ (A)
R O
--1 0--
.

12~64fi6
Me le
II.Me-Si-O-Si-Ne +n~A)
Me Me
HNR
Me ~ Me Me
Me-Si ~ O-Si [O-S~ ~ O-Si-Me
Me Me Me 3 n Me
A wide variety of allylamines and corresponding ~-
butenyl and ~-pentenylamines are useful in this synthesis.
~owever, as is well known, amines such as the sècondary
alkylamines, for example dimethylamine and dipropylamine, as
well as (primary) allylamine itself, fail to react in a
satisfactory and reproducible manner. For example, U.S. Patent
3,665,027 discloses the reaction of allylamine with a monofunc-
tional hydrogen alkoxysilane. Despite the presence of the
activatin~ alkoxy groups and exceptionally long reaction times,
the reaction provided at most an 85 percent yield. Further-
more, the reaction produces considerable quantities of poten-
tially dangerous peroxysilanes as by-products. For these
reasons, the preparation disclosed is not a desirable one for
producing even monofunctional ~-aminopropyl trialkoxy silox-
anes. Attempts to utilize the reaction for the preparation of
higher functionality siloxanes, particularly alkyl-substituted
iloxanes such as the poly(dimethyl~silicones, have not proven
successful. It is also known that use of vinylamine leads only
to intractable products of unspecified composition.
'~
-11-
. .
.

129~fi6
One reason that such processes produce poor and
irreproducible results is the well known fact that primary
amines poison platinum catalysts. The greater amount of amine
present per mole of catalyst, the greater the degree of
catalyst alteration. Thus where an amine such as allylamine or
vinylamine is added in mole-to-mole correspondence with the
hydrogen ~unctionality of the hydrogen functional organosili-
cone, the expected catalyst function is disrupted and numerous
side reactions, including polymerization of the vinyl or allyl
compounds may occur. Thus it is necessary that the amine be a
secondary, N-allylamine or secondary, N-(unsaturated alkyl-
amine) wherein the double bond is located at least two carbons
from the secondary amino nitrogen.
In the list of suitable secondary allylamines which
follows, it should be noted that the corresponding ~-butenyl
and 6-pentenylamines are also suitable. Examples of amines
~hich are suitable, include N-alkyl-N-allyl amines such as N-
methyl, N-ethyl, N-propyl, N-isopropyl, N-butyl, N-isobutyl, N-
tert-butyl, and N-12-ethylhexyl)allylamines and the like;
cycloaliphatic-N-allylamines such as N-cyclohexyl, N-(2-
methylcyclohexyl), and N-(4-methylcyclohexyl)-N-allylamines;
aliphatic cycloaliphatic-N-allylamines such as N-cyclohexyl-
methyl and N-(4-methylcyclohexylmethyl)-N-allylamines; aralkyl
taromatic-aliphatic)-N-allylamines such as N-benzyl, N-(4-
methylbenzyl), N-(2-methylbenzyl), and N-(4-ethylbenzyl)-N-
-12-

~2969~fi6
allylamines aryl [aromatic)-N-allylamines such as N-phenyl, N-
(4-methylphenyl), N-~4-nonylphenyl), and N-naphthyl-N~
allylamines; and aromatic N-allylamines where the aromatic
component has the formula
~X~
where X is
A A O O
-C~2-, -CH-,-C-, -S-, -S-, -S- and 0, and where A is Cl-C6
A O
lower alkyl.
While these and many other N-allyl secondary amines
are useful for the practice of the subject invention, it must
be recognized that Qome are more preferred than others. In
general, the cycloaliphatic and aryl-N-allylamines are pre-
ferred. Particularly preferred are N-cyclohexyl-N-allylamine
and N-phenyl-N-allylamine. It should be noted that the
secondary N-allyl amines are more preferred than their
~-butenyl and 6-pentenyl analogues.
-13-
... . . . ..... . . .

lZ96466
As the Si-H functional organosilicone may be used
compounds of the formulas: ~
R -I ~ O-l 3 R2 and ~
wherein R2 is selected from the group consisting of hydrogen;
alkyl, preferably Cl-C12 lower alkyl; alkoxy, preferably Cl-C12
lower alkoxy; acetoxy; cyanoalkyl; halogenated alkyl, prefer-
ably perhalogenated alkyl; and substituted or unsubstituted
cycloalkyl, aryl, or aralkyl; and
~ o-li ~ R
wherein m and n are natural numbers from 0 to about 10,000,
preferably from 0 to about 500 and more preferably from 1 to
about 100; wherein p i8 a natural number from 3 to about 20,
preferably from 4 to about 8; and wherein the sum n+m i8 less
than about 10,000, preferably less than about 500, more
preferably less than about 100; and wherein at least one R2 is
hydrogen. ~ost preferably, the Si-H functional organosilicone
'
14-
:

- ` 12g6466
is an Si-H functional disiloxane, preferably
R2 R2
H-Si-0-Si-H,
l2 l2
where R2 is cyanoalkyl, halogenated alkyl, alkyl, alkoxy,
cycloalkyl, or aryl. Examples of such Si-H functional organo-
silicones are trimethoxy- and triethoxysilane, tetramethyldi-
siloxane, tetraethyldisiloxane, 1,1,3,3,5,5-hexamethyltri-
siloxane, methyltris(dimethylsiloxysilane), 1,1,3,3,5,5,7,7-
octamethyltetrasiloxane, tetramethoxydisiloxane, tetraethoxy-
disiloxane, l,l-bis(trifluoropropylJ-3,3-dimethyldisiloxane,
pentamethylcyclopentasiloxane, heptamethylcyclotetrasiloxane,
tetramethylcyclotetrasiloxane, methylhydrosiloxane-dimethyl-
siloxane copolymers, and tetraphenyldisiloxane. Particularly
preferred because of its low cost and ready availability is
tetra~ethyldisiloxane. ~ixed-substituted alkyl-aryl siloxanes
such~as 1,3-dimethyl-1,3-diphenyldisiloxane are also useful.
The N-allyl Qecondary amine and Si-H functional
organosilicone are preferably reacted neat, in the absence of
solvent. However solvents which are inert under the reaction
conditions may be utilized if desired. The use of solvent may
-15-

129646~i
affect both the average molecular weight of the productpolysiloxane and the molecular weight distribution.
The reaction temperature is preferably maintained
between about 20C and 150C dependinq upon the nature and
amount of catalyst and reactants. A catalyst is generally
necessary to promote reaction between the amine and the Si-H
functional organosilicone. Surprisingly, it has been found
that even rather inefficient catalysts such as hexafluoro-
platinic acid and hexachloroplatinic acid are highly effective,
frequently resulting in quantitative yields. Other catalysts
which are useful include those well known in the art, typically
platinum catalysts in which the platinum is present in ele-
mental or combined states, particularly di- or tetravalent
compounds. Useful catalysts are, for example, platinum
supported on inert carriers such as aluminum or silica gel;
platinum compounds such as Na2PtC14, K2PtC14, and the pre'
viously mentioned platinic acids, particularly hexachloro- and
hexafluoroplatinic acids. Also useful are alkylplatinum
halides; siloxyorganosulfur-platinum or aluminoxyorganosulfur-
platinum compositions, and those catalysts prepared through the
reaction of an olefinic-functional siloxane with a platinum
compound as disclosed in U.S. Patents 3,419,593; 3,715,334;
3,814,730; and 4,288,345. Other catalysts may also be effec-
tive, such as those found in U.S. Patent 3,775,452.
-16-

1296466
~owever, because ~f its (relatively) low cost and the-high
yields it produces, hexachloroplatinic acid is the catalyst of
choice.
Purification of the secondary amine-functionalized
organosilicone pr~duct is accomplished by methods well known to
those skilled in the art of purifying silicones. Generally,
vacuum distillati3n is utilized, for example distillation at
pressures less than about 1 torr. In some cases, purification
may be effectuated by stripping off light fractions under
vacuum, optionally with the aid of an inert stripping agent
such as nitrogen or argon.

~ g~46~;
The secondary amine-functionalized organosilicones
may be utilized as such, or they may be further polymerized
with additional silicon-containing monomers to produce higher
molecular weight secondary amine-functionalized polysilox-
anes. For example, a secondary amine-functionalized tetra-
methyl disiloxane may be converted easily to a secondary amine-
terminated poly(dimethylsiloxane) by equilibration with
octamethylcyclotetrasiloxane:
Me Me Me
r 1 1
7 V I ¦i V 7H ~ n ~ -Si
R Me Me R ¦ Me
Me Me
~N ~ Si- ~ li ~ 7H
R Me 4n+1 Me R
The equilibration co-polymerization is facilitated through the
use of catalysts well known to those skilled in the art. A
particularly useful catalyst which is relatively inexpensive
and readily available is tetramethylammonium hydroxide.
Rowever, many other catalysts are also suitable, such as
potassium hydroxide, cesium hydroxide, tetramethylammonium
siloxanolate, and tetrabutylphosphonium hydroxide, which are
also preferred.
-18-
. ~. ... . . . .. ~ , .

-
:lZ96~66
If copolymer polysiloxanes are desired, then a
diferent siloxane comonomer may be added to the reaction
mixture. For example, a secondary amine-terminated tetra-
me~hyldisiloxane may be reacted on a mole to mole basis with
octaphenylcyclotetrasiloxane to produce a copolymer poly-
siloxane having the nominal formula:
Me Ph Me
HN ~ Si-O ~ Si-O ~ Si ~ NH.
R Me 5 Ph 4 Me R
Or, in the alternative, the secondary amine-terminated di-
siloxane or polysiloxane may be reacted with mixtures of
siloxane monomers to form block and block heteric structures.
The synthesis of secondary amine-functionalized
organo~ilicone modifiers may be illustrated by the following
preparative examples, which should not be considered as
limiting in any way. All reagent quantities are by weight or
by gram-mole,as indicated.
--19--
:
.

lZ96466
Example 1
Synthesis of 1,3-bis(N-phenyl-3-aminopropyl~-1,1,3,3-~etra-
methyldisiloxane.
N-allylaniline ~0.200 mole) and 1,1,3,3-tetramethyl-
disiloxane (0.100 mole) are introduced along with 0.05 9
hexachloroplatinic acid into a 100 ml cylindrical glass reactor
equipped with reflux condenser, nitrogen inlet, and stir bar.
The contents of the reaction are heated and maintained while
stirring, at approximately 70C, for a period of ten hours.
The IR spectrum of the resulting viscous oil shows no peaks
corresponding to Si-H, indicating completion of the reaction.
The crude product is mixed with carbon black and stirred
overnight at room temperature. The product is filtered through
silica gel and the filter cake washed with toluene. Volatile
fractions are removed by stripping under vacuum at 150C to
give a slightly colored oil. The oil is further purified by
vacuum distillation at <1 torr at 223-230C. The yield of 1,3-
bis(N-phenyl-3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is
virtually quantitative.
; -20-

1296466
ExamPle ?
Synthesis of 1,3-bis(N-cyclohexyl-3-aminopropyl)-1,1,3,3-
tetramethyldisiloxane.
Following the technique described in Example 1, N-
allylcyclohexylamine (0.173 mole), 1,1,3,3-tetramethyldi-
siloxane (0.0783 mole), and 0.05 9 hexachloroplatinic acid are
stirred at 70C for eight hours at 110C under nitrogen. The
product, in nearly quantitative yield, is purified by vacuum
distillation at ~1 torr at a temperature of 207-210C.
Example 3
Synthesis of ~,~-bis(N-phenyl-3-aminopropyl)polysiloxane
copolymer.
Into a 500 ml glass reactor equipped with a reflux
condenser, mechanical stirrer, and nitrogen inlet are intro-
duced 1,3-bis(N-phenyl-3-aminopropyl)-1,1,3,3-tetramethyl-
disiloxane (0.100 mole), octamethylcyclotetrasiloxane ~0.270
mole), octaphenylcyclotetrasiloxane (0.100 mole), and tetra-
methylammonium hydroxide (0.3 9). The reaction mixture is
stirred at B0C for 44 hours followed by an additional 4 hours
at 150C, all under nitrogen. The resultant viscous oil is
filtered and volatiles removed under vacuum at 300C. The
resulting copolymer is obtained in high yield as a slightly
colored viscous oil.
-21-

lZ96466
Example 4
Synthesis of ~ bis(N-cyclohexyl-3-aminopropyl capped poly-
siloxane copolymer.
Utilizing the procedure of Example 3, 1,3-bis(N-
cyclohexyl-3-aminopropyl)-1,1,3,3-tetramethyl disiloxane
(0.0485 moles), octamethylcyclotetrasiloxane (0.179 moles),
octaphenylcyclotetrasiloxane ~0.067 mole) and tetramethyl-
ammonium siloxanolate (1.20 g) are allowed to react over a
period of 40 hours at 90C and an additional 4 hours at
150C. After cooling to room temperature, the filtered
reaction mixture is vacuum stripped at <1 torr and 250C to
yield a viscous oil in high yield.
Exam~le 5
Synthesis of ~,~-bis(N-phenyl-3-aminopropyl) Capped
Polydimethylsiloxane
1,3-Bis(N-phenyl-3-aminopropyl)-1,1,3,3-tetramethyl-
disiloxane (30.0 9), octamethylcyclotetrasiloxane (12.0 9), and
tetramethylammonium hydroxide (0.06 9) are charged to a 500 ml
glass reactor equipped with a reflux condenser, nitrogen inlet,
and mechanical stirrer. The contents of the reactor are
stirred at 80C for 30 hours, then at 150C for four hours
under N2 blanket. After filtration, the filtrate was further
purified by eliminating volatile fractions under vacuum at
180C. The resulting oligomer was a colorless viscous oil.
-22-
,

~96466
Exam~le 6S~nthesis of an ~ bis(N-phenyl-3-aminopropyl) Capped
Polydimethylsiloxane
1,3-Bis(N-phenyl-3-aminopropyl)-1,1,3,3-tetramethyl-
disiloxane (4.0 9) is treated with octamethylcyclotetrasiloxane
(100 g) and tetramethylammonium hydroxide (0.06 g) in a manner
similar to that described in Experiment 5. The resulting
oligomer is a colorless viscous oil having an average molecular
weight of about 10,000.
Example ?
Synthesis of a Siloxane Polymer
1,3-Bis(N-cyclohexyl-3-aminopropyl)-1,1,3,3-tetra-
methyldisiloxane (4.0 9) is treated with octamethylcyclotetra-
siloxane (100 g) and tetrabutylphosphonium hydroxide (0.06 g)
at 110C for four hours and 150C for three hours under
nitrogen. Filtration followed by elimination of volatile
fractions under vacuum at 160C gives a secondary amine
terminated silicone oligomer having an average molecular weight
of about 10,000.
-23-

1296466
Examples of thermosetting resin systems with which
the subject invention modifiers are useful include but are not
limited to epoxy resins, cyanate resins, maleimide-group-
containing resins, isocyanate resins, unsaturated polyester
resins, and the like. Particularly preferred are those resins
which are reactive with secondary amines. Most preferred are
the epoxy, cyanate, and maleimide resins.
Epoxy resins are well known to those skilled in the
art. Such resins are characterized by having an oxiranyl group
as the reactive species. The most common epoxy resins are the
oligomeric resins prepared by reacting a bisphenol with
epichlorohydrin followed by dehydrohalogenation. Preferred
bisphenols are bisphenol S, bisphenol F, and bisphenol A,
particularly the latter. Such resins are available in wide
variety from numerous sources. Aliphatic epoxy resins are also
useful, particularly those derived from dicyclopentadiene and
other polycyclic, multiply unsaturated systems through epoxida-
tion by peroxides or peracids.
For high temperature, high strength applications,
epoxy resins containing dehydrohalogenated epichlorohydrin
derivatives of aromatic amines are generally used. The most
preferred of these resins are the derivatives of 4,4'-
methylenedianiline and p-aminophenol. Examples of other epoxy
resins which are usefuI may be found in the treatise Handbook
-24-

~2~6466
of Epoxy Resins by Lee and Neville, McGraw-Hill, New York, c.
1967.
The epoxy resins described above are seldom used
alone but are generally cured by means of a curing agent
reactive with the oxirane group. Suitable curing agents
include primary and secondary amines, carboxylic acids, and
acid anhydrides. Examples of suitable curing agents may be
found in ~ee and Neville, supra, in chapters 7-12. Such curing
agents are well known to those skilled in the art. A particu-
larly preferred curing agent for elevated temperature use is
4,4'-diaminodiphenylsulfone.
The maleimide-group containing resins useful for the
practice of the subject invention are generally prepared by the
reaction of maleic anhydride or a substituted maleic anhydride
such as methylmaleic anhydride with an amino-group-containing
compound, particularly a di- or polyamine. Such amines may be
aliphatic or aromatic. Preferred maleimides are the bis-
maleimides of aromatic diamines such as those derived from the
phenylenediamines, the toluenediamines, and the methylenedi-
anilines. A preferred polymaleimide is the maleimide of
polymethylenepolyphenylenepolyamine (polymeric MDA).
In addition to the aromatic diamines described above,
aliphatic maleimides derived from aliphatic di- and polyamines
are useful. Examples are the maleimides of 1,6-hexanediamine,
-25-

~Z96466
1,8-octanediamine, l,10-decanediamine, and 1,12-dodecanedi-
amine. Particularly preferred are low melting mixtures of
aliphatic and aromatic bismaleimides. These and other
maleimides are well known to those skilled in the art.
Additional examples may be found in U.S. Patents 3,018,290;
3,018,292; 3,627,780; 3,770,691; 3,770,705; 3,839,358:
3,966,864; and 4,413,107. In addition, the polyaminobis-
maleimides which are the reaction product of an excess of
bismaleimide with a diamine as disclosed in U.S. Patent
3,562,223 may be useful. Also useful are bismaleimide composi-
tions containing alkenylphenolic compounds such as allyl and
propenyl phenols as disclosed in U.S. Patents 4,298,720 and
4,371,719. In addition to being useful with bismaleimides,
such comonomers may be useful in resin compositions containing
epoxy and cyanate resins.
Cyanate resins may also be used to advantage in the
subject invention. Such resins containing cyanate ester groups
are well known to those skilled in the art. The cyanates are
generally prepared from a di- or polyhydric alcohol by reaction
with cyanogen bromide or cyanogen chloride. Cyanate resin
preparation is described in U.S. Patent 3,740,348, for
example. Preferred cyanates are the cyanates derived from
phenolic hydrocarbons, particularly hydroquinone, the various
bisphenols, and the phenolic novolak resins such as those
disclosed in U.S. Patents 3,448,071 and 3,553,244.
-26-

lZ96466
~ he cyanate and epoxy resins are frequently used incombination, as these resins appear to be compatible ~ith each
other. Examples of epoxy/cyanate compositions are disclosed in
U.S. Patents 3,562,214 and 4,287,014.
The following examples illustrate the use of sec-
ondary amine-functionalized siloxanes in matrix resin and
adhesive formulations.
Example 8 - Epoxy Resin Prereact
A prereact is prepared by heating to 145C~ for two
hours under nitrogen, a mixture containing 15.0 g of the
secondary amine-functionalized silicone oligomer of Example 4
and 13.8 9 of DER~ 332, an epoxy resin which is a diglycidyl
ether of bisphenol A available from the Dow Chemical Company,
Midland, MI, which has an epoxy equivàlent weight of from 172
to 176. The resulting product is a homogenous, viscous oil.
Exam~le 9 - Curable Resin Adhesive Composition
~ o 2.88 g of the prereact of Example 8 is added 2.0 g
Tactix~ 742, a glycidyl ether of tris(4-hydroxyphenyl)methane,
and 2.62 g DER~ 332, both products of the Dow Chemical
Company. The mixture was stirred at 100C for 30 minutes.
Upon cooling to 70C, 2.0 g of 4,4'-diaminodiphenylsulfone and
0.5 9 of a fumed silica ~CAB-0-SIL~ M-5, available from Cabot
-27-

~;~96466
Corporation) are introduced with stirring. A catalyst solution
is prepared separately by mixinq 0.8 9 2-methylimidaz~le with
10.0 9 DER~ 332 at room temperature. Following addition of
0.35 9 of the catalyst solution to the resin, the mixture was
coated onto a 112 glass fabric.
ExamPle 10 - Comparison Adhesive
A comparison resin similar to the resin of Example 9
was prepared by coating 112 glass fabric with a similarly
prepared mixture containing 2.0 9 Tactix~ 742, 4.0 g DER~ 332,
2.0 9 4,4'-diaminodiphenylsulfone, 0.5 g CAB-0-SIL M-5, and
0.35 9 of the catalyst solution as prepared in Example 9.
The adhesive films of Examples 9 and 10 were cured by
heating at 177 for four hours, 200C for two hours, and 250
for one hour. Single lap shear strengths were measured by the
method of ASTM D-1002. The comparative test results are
presented in Table I below.
-28-

12~64~
TABLE I
Al/Al Lap Shear Strenqths of Cured Adhesive Compositions
Test Conditions Lap Shear Strength lb/in2
Example 9 Example 10
(with modifier) (comparative -
no modifier)
Ambient, initial 2840 2130
177C, initial 3290 2660
Ambient, agedl 2370 1810
177C, agedl 3010 2S60
Aging at 177C for 500 hours
Exam~les 11, 12 - Curable Resin Elastomer Compositions
The secondary amine-functionalized silicone oligomers
from Examples 6 and 7 respectively (1.6 g) were treated with
0.1 g Tactix~ 742 and 0.3 g DER~ 332 at 130C for one hour.
Following addition of 0.15 g 4,4'-diaminiodiphenylsulfone, the
resulting resin systems were cured at 177C for two hours and
200C for three hours. The cured elastomers demonstrated
improved strength as compared to cured ~ilicone homopolymers.
- 29 -

~296466
Thermal stabilities of the cured elastomers were examined by
thermogravimetric analysis (TGA). The results are illustrated
in Table II.
TABLE II
_ TGA (C) in Air _
5% wt. loss 10% wt. 105s
Example 11 380 405
Example 12 350 380
ExamDle 13 - Prereact
A mixture of the secondary amine-functionalized
silicone oligomer from Example 4 (30.0 g) Taxtix~ 742 l33.8 g),
and DER~ 332 (22.1 g) is heated to 140C for three hours. The
resulting product is a homogeneous viscous oil.
Example 14 - Resin Adhesive
The prereact of Example 13 (28.5 9) i~ mixed with
Tactix~ 742 (12.8 g), DER~ 332 l4.3 g), and Compimid~ 353
(Boots-Technochemie, 16.0 g) at 130C for 30 minutes. At 70C,
3,3'-diaminodiphenylsulfone (13.8 g), 4,4'-bis(p-aminophenoxy)-
diphenylsulfone (6.1 g), and CAB-0-SIL M-5 (1.8 g) are intro-
duced. The final resin mixture i8 coated on a 112 glass
fabric. The adhesive film i8 cured by being heated for four
- 30 -

1296466
hours at 177C, two hours at 220C, and one hour at 250C. The
single lap shear strengths tAl~Al) are 2200-psi at 20~C and
2500 psi. at 205C, respectively.
Example 15 - Curable Resin ComPositions
A mixture of the secondary amine-functionalized
silicone oligomer (15.0 9) from Example 3, Compimide 353
~10.0 9), and benzoic acid ~0.1 g) is heated to 140C for six
hours under N2 with vigorous stirring. To the resulting
mixture, additional Compimide (10.0 9) and tetra(o-methyl)bis-
phenol F dicyanate (70.0 9) are added. The mixture is stirred
at 120C for 30 minutes under vacuum. At 70C, CAB-0-SIL
(N70-TS, 2.6 9) and dibutyltindilaurate 10.15 9) are intro-
duced. The final resin mixture is coated on a 112 glass
fabric.
ExamDle 16 - Comparative Curable Resin ComDosition
A resin formulation is made in a similar manner to
Example 15 from a 2-piperazinyl ethyl amide terminated buta-
diene-acrylonitrile copolymer (Hycar~ ATBN 1300 x 16, B.F.
Goodrich Co.,) (15.0 9), Compimide 353 (20.0 g), tetra(o-
methyl)bisphenol F dicyanate t70.0 9), CAB-0-SIL N70-TS (2.6 q)
and the dibutyltindilaurate catalyst ~0.15 9). In this case,
pretreatment is carried out by adding the ATBN modifier to

Compimide 353 at 120C under N2 while stirring.
The adhesive films of Examples 15 and 16 are cured by
being heated for four hours at 177C, four hours at 200C, and
two hours at 230C. The single lap shear strengths (Al/Al) of
these formulations are shown in Table III.
TABLE III
Al/Al Lap Shear Strengths of Cured Adhesive Compositions
Test ConditionsShear Strength, lb,/in2
Example 15 Example 16
(silicone modified) (AT9N modified)
20C 3280 2670
205C 3800 2900
~ he foregoing examples illustrate the versatility of
secondary amine-functionalized organosilicones as modifiers for
a variety of resin systems. The stoichiometry of the systems
may be readily adjusted to enable those skilled in the art to
produce elastomer modified high strength matrix resins, high-
temperature, high-strength elastomers, and high performance
structural adhesives. In the claims which follow, the term
nresin systemH is utilized in its conventional meaning, i.e. a
-32-

1 Z~6466
syitem characterized by the presence of a substantial amount of
a heat curable resin together with customary catalysts and
curing agents but devoid of the secondary amine-functionalized
si:Licone modifiers of the subject invention.
The modified resin systems of the subject invention
may be used as hiyh performance structural adhesives, matrix
resins, and elastomers. These compositions are prepared by
techni~ues well known to those skilled in the art of struc~ural
materials.
The adhesives, for example, may be prepared as thin
films from the melt, or by casting from solution. Often, the
films do not have enough structural integrity to be handled
easily. In this case, the adhesive is generally first applied
to a lightweight support, or scrim. This scrim may be made of
a wide variety of organic and inorganic materials, both woven
and non-woven, and may be present in an amount of from about 1
to about 25 percent by weiqht relative to the weight of the
total adhesive composition. The scrim adds little or no
strength to the cured adhesive film, but serves to preserve the
integrity of the film in its uncured state. Common scrim
compositions include fiberglass, carbon/graphite, polyester,
and the various nylons.
When used as a matrix resin, the compositions of the
subject invention are applied to fiber reinforcement. The
-33-

~Z96466
resin/reinforcement ratio can vary widely, but most prepregs
prepared using the subject compositions will contain from 10 to
60 percent by weight, preferably from 20 to 40 percent by
weight, and most preferably from about 27 to 35 percent by
weight of matrix resin, the balance being reinforcing fibers.
The reinforcing fibers may be woven or non-woven, collimated,
or in the form of two or three dimensional fabric, or may, in
the case of casting resins, be chopped.
In contrast to the scrim material used in adhesives,
the reinforcing fibers in prepregs contribute substantially to
the strength of the cured prepreg or composite made from
them. Common reinforcing fibers utilized are carbon/graphite,
fiberglass, boron, and silicon; and high strength thermoplas-
tics such as the aramids, high modulus polyolefins; polycarbo-
nates; polyphenylene oxides; polyphenylene sulfides; polysul-
fones; polyether ketones (PEK), polyether ether ketones (PEEK),
polyether ketone ketone (PEKK) and variations of these;
polyether ~ulfones; polyether ketone sulfones; polyimides; and
polyether imides. Particularly preferred are those thermoplas-
tics having glass transition temperatures (Tg) above 100C,
preferably above 150C, and most preferably about 200C or
higher.
When utilized as heat curable elastomers, the
modified resins of the subject invention may or may not contain
-34-