Note: Descriptions are shown in the official language in which they were submitted.
~ 1384 ~ I
,
^ ` CURABLE POLY(ALKYLENE)ETHER POLYOL-BASED RESINS
; HAVING IMPROVED PROPERTIES
Louis J. Baccei
. BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to certain poly(alkylene)ether polyol-
~based resins, curable by peroxy initiation, and having improved
impact, and cure-through-volume properties as well as good over-
all properties. More specifically, it relates to resins which may
be viewed as a reaction product of poly(alkylene)ether polyols,
preferably diols, with, e.g., methacrylate-capped aromatic diiso- ,
cyanates.
Prior Art
It is known that curable anaerobic resins having desirable
properties may be prepared as the reaction product of an organic
polyisocyanate and an acrylate ester having an active hydrogen in
the non-acrylate portion of the ester. Such resins are disclosed
in U. S. Patent 3,425,988 to Gorman et al. This patent relates
- ~specifically to monofunctional, acrylate-terminated material which¦
is reacted with organic polyisocyanate in such proportions as to
` convert all of the isocyanate groups to urethane or ureide groups.~
The acrylate esters are preferably the acrylates and methacrylates,
containing hydroxy or amino functional groups on the non-acrylate
portions thereof.
It is also known that poly(alkylene)ether glycols may be
reacted-with organic isocyanates to form urethane prepolymers
which are subsequently cured by reaction with an active hydrogen
molecule, e.g., with alcohols, amines, water, or other agents.
~,
Such systems are two-part systems, that is, the alcohol or amine
- 1 -
~ .
' ``` : ~ ( ;
V~3~4 1,
must be kept separate from the prepolymer until the time of actual
use since the mixed system has very limited pot life. As would be
- expected, the mixing of these viscous liquids leads to problems of
nonhomogeniety and therefore imperfect cure, as well as causing
substantial inconvenience. Similar urethane coatings curable
- through the action of moisture are also known, but have the defect',
that cure begins as soon as the coating is spread, thereby inter-
,fering with control of the coating operation and causing incon- ~
, venience. I
SUMMARY OF THE INVENTION
!.
Now, however, there is provided a polymerizable composition
~based on prepolymers which are derived from the reaction between
poly(alkylene)ether polyols, preferably glycols, and organic poly-
isocyanates, preferably diisocyanates, which can be prepared as a
one-part system having long pot life and more controllable cure
I
characteristics. The prepolymers of this invention are also
- ,characterized by being acrylate, e.g., methacrylate, terminated.
These prepolymers are curable by free radical generating initiatorq,
.:. !
~e.g., peroxy compounds or ultraviolet-sensitive compounds. When
20 Iformulated with hydroperoxides, they acquire anaerobic curing
~characteristics. The compositions of this invention have broad
utility as adhesives, sealants and coatings and generally provide,~
among other benefits, improved physical properties such as
excellent tensile and impact strengths, good flexibility even at
low temperatures, and excellent ability to cure through quite
large gaps, e.g., 40-50 mils or more. I
Specifically, the present invention provides a curable com- '-
position comprising:
I. a polymerizable product corresponding in structure to a
30 reaction product of:
- 2 -
-``` 10~3t~4
: (a) a poly(alkylene)ether polyol (preferably glycol)
with: .
(b) at least a molar equivalent of a reaction product
of: at least a molar equivalent of an aromatic or
cyclo-aliphatic polyisocyanate with a compound
: selected from the group consisting of an aromatic
or cyclo-aliphatic polyol or polyamine,
the product of (a) and (b) subsequently being reacted with
at least a molar equivalent of a hydroxyalkyl acrylate, a
hydroxyalkyl methacrylate, an aminoalkyl acrylate, or an
aminoalkyl methacrylate; and
II. A free radical initiator.
There is also provided a process for preparing the .
: monomer of Part I, above, comprising reacting the poly-
(alkylene)ether polyol of Part I(a) with
. at least a molar equivalent of a reaction product of:
at least a molar equivalent of an aromatic or cyclo-
aliphatic polyisocyanate with a compound selected from
the group consisting of an aromatic or cycloaliphatic
polyol or polyamine,
- the product subsequently being reacted with at least a
molar equivalent of a hydroxyalkyl acrylate, a hydroxy-
~ alkyl methacrylate, an aminoalkyl acrylate, or an
: aminoalkyl methacrylate.
In addition, there is provided a process for sealing
or adhering surfaces which comprises applying to at least
one of said surfaces the above polymerizable compositions,
then placing said
,
-- 3 --
'~)
lU9~38~ i
:
surfaces in an abutting relationship until the composition has
cured.
DETAILED DESCRIPTION OF THE I~VENTION
The monomer of the present invention may be viewed as a one-
component polymerizable block copolymer (prepolymer) having well-
! defined rigid and flexible segments. This is achieved by thechemical linking of two precursor "prepolymers" which are subse-
quently "capped" with acrylate, e.g~, methacrylate, functionality.
Accordingly, in a preferred embodiment, a "flexible" polymeric
methylene ether diol segment of relatively low molecular weight
:is reacted with a molar excess of a "rigid" diisocyanate such as
itoluene diisocyanate or methylene diisocyanate (4,4'-diisocyanato j
-~ diphenylmethane), thereby forming urethane linkages. Before
:reacting with the poly(alkylene)ether diol, the diisocyanate is
preferably reacted in excess with another rigid moiety containing
at least two active hydrogen atoms, such as in hydroxy or amine
groups, thereby capping the other rigid moiety with -NCO groups.
: . .
~;, By the term "rigid" segment is meant a segment or segments con-
taining aromatic,heterocyclic or cycloaliphatic rings. If multiple
segments are involved, they should be joined by either fusing of
the rings or by a minimum of carbon atoms (e.g., 1-2 if linear,
1-about 8 if branched) or hetero atoms such that there is little
or no flexing of the segments. By the term "flexible" segment is ~
meant a segment comprising primarily linear aliphatic ether moieties.
Pendent functional groups, including aromatic, heterocyclic and
cycloaliphatic, among others, as well as branching, may also be
incorporated, provided that there is no substantial interierence
'
. '
10913~3~
with the necessary flexible nature of the linear portion nor
degradation of the cured resin properties disclosed herein.
Illustrative of the polyisocyanates employed in the
preparation of the new monomers are, amoung others, phenyl diiso-cyanate, toluene diisocyanate, 4,4'-diphenyl diisocyanate, 4,4'-
diphenylene methane diisocyanate, dianisidine diisocyanate, 1,5-
~ naphthalene diisocyanate, 4,4'-diphenyl ether diisocyanate,
. p-phenylene diisocyanate, 4,4'-dicyclo-hexylmethane diisocyanate,
. 1,3-bis-(isocyanatomethyl) cyclohexane, cyclohexylene diisocyanate,
10 tetrachlorophenylene diisocyanate, 2,6-diethyl-p-phenylenediiso-
cyanate, and 3,5-diethyl-4,4l-diisocyanatodiphenyl-methane.
t Still other polyisocyanates that may be used are the higher
molecular weight rigid polyisocyanates obtained by reacting
polyamines containing terminal, primary and secondary amine
groups or polyhydric alcohols, for example, the alkane, cyclo-
alkane, alkene and cycloalkene polyols such as gylcerol, ethylene
glycol, bisphenol-A, 4,4'-dihydroxyphenyldimethylmethane-substi-
. tuted bisphenol-A, and the like, with an excess of any of the
above-described isocyanates. These higher molecular weight
20 urethane or ureide polyisocyanates may be represented by the
formula:
H O
-
~ [O=C=N-R -N-C-X ]nB
- wherein Rl is an organic radical selected from the group consist-
ing of alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, aralkyl
and alkaryl radicals of 2 to about 20 carbon at.oms, both substi-
RZ
tuted and unsubstituted; X is -O- or -N- , wherein R2 is hydrogen
or lower alkyl of 1 to 7 carbon atoms; B is a polyvalent organic
radical selected from the group consisting of cycloalkyl, cyclo-
alkenyl, aryl, aralkyl,alkaryl and heterocyclic radicals, both:'
109~384
substituted and unsubstituted; and n is an integer from 2 to
about 6.
As indicated above, the diisocyanate is preferably
reacted with another rigid segment comprising an aromatic, heter-
ocyclic or cycloaliphatic compound containing at least two
active hydrogen atoms, preferably diamines and more preferably
diols. Suitable compounds are 2,2-(4,4'-dihydroxydiphenyl)-pro-
pane (i.e., bisphenol-A), 4,4'-iso-propylidenedicyclohexanol
(i.e., hydrogenated bisphenol-A), ethoxylated bisphenol-A,
propoxylated bisphenol-A~2~2-(4~4l-dihydroxydiphenyl)-butane~3~3-
(4,4'-dihydroxydiphenyl)-pentane,~,~ ,'-(4,4'-dihydroxydiphenyl)-
p-diisopropylbenzene, 1,3-cyclohexane diol, 1,4-cyclohexane diol,
1,4-cyclohexanedimethanol, bicyclic and tricyclic diols such as
4,8-bis-(hydroxymethyl)-tricyclo [5.2.1.02'6] decane, 2,2,4,4-
,~.tetramethyl-1,1,3-cyclobutanediol, hydroquinone, resorcinol,2,2-
: (4,4'-dihydroxydiphenyl)-sulfone, and 4,4'-oxydiphenol, among
others, as well as halogenated derivatives of the above, such
as tetrabrominated ethoxylated bisphenol-A. These ring
compounds may also be substituted with either reactive groups
or unreactive groups such as alkyl groups containing about 1 to 4
carbon atoms. This reaction may be carried out at temperatures
from room temperature to about 180C, preferably about 40-120C,
depending upon the specific reactants selected. At the lower
temperatures, use of standard catalysts may be desirable.
; Unreactive diluents may be used, if desired.
- The polyisocyanate thus formed is reacted with a
polymeric alkylene ether compound having at each end of the
chain a functional group containing a reactive hydrogen atom,
preferably in a hydroxyl group.
. .
,.,
--6--
1091384
The ply(alkylene) ether or copoly (alkylene) ether
compounds of this invention conform to the formula:
HO~Hz~xO)) y~CH~CH~O~H
wherein x is an integer from l~to about 8, y is an integer from
0 to about 20, z is an integer from 0 to about 10, and n is an
integer of about 1 to about 100. Preferably, x is 2 to about 6,
y is 1 to about 5, z is 0 to 2, and n is 3 to about 60. More
preferably, x is 4 to about 6, y is 1 to 2, z is 0 to 1, and n is
5 to about 40. R3 and R4 may be hydrogen, lower alkyl radicals
containing 1 to about 3 carbon atoms, cycloaliphatic, cycloalkenyl
or aromatic radicals comprising up to about 8 carbon atoms and
heterocyclic radicals comprising up to about 8 carbon/hetero
atoms. It is also highly desirable that the glycol be linear in
order to provide a high degree of flexibility in the segment.
Suitable linear polyols would include poly(tetramethylene) ether
glycol and poly(ethylene) ether glycol, among others. Represen-
~ tative branched polyols include poly(l,2-propylene) ether polyol
- 20 and poly(l,2- or 1,3-butylene) ether glycol. Preparation and
properties of polyols of these types are discussed in the
literature, e.g., Saunders, J.H., and Frisch, K.C., "Poly-
urethanes - Chemistry and Technology, "Interscience, New York,
New York, (1963).
In a preferred embodiment, the flexible poly(alkylene3
ether having functional groups containing an active hydrogen
is reacted with the polyisocyanate in such proportion that the
polyisocyanate is present in molar excess as to the concentration
of the active hydrogen-containing groups. In this way a product
is assured which has an -NCO group at each end of the poly
(alkylene) ether segment. The molar excess of polyisocyanate may
vary from about 0.05 to about 6.
;
``
1~)913~
;This reaction may be carried out at temperatures from about
room temperature to about 150C, preferably from about 40C to
about 120C. After addition of the flexible diol, about 0.1 to
30 hours are required for completion at the preferred temperature j
range. The reaction may also be catalyzed, if desired, and un-
reactive diluents may be used for viscosity control.
The product of the above reaction is reacted with a molar
` equivalence, preferably a molar excess, based on -NCO group con-
;tent, of an acrylate or methacrylate ester containing a hydroxy
10 lor amine group on the nonacrylate portion thereof. This results
in an adhesive/sealant monomer, or more accurately, prepolymer,
capped at both ends with acrylate or methacrylate functionality.
,Esters suitable for use in this invention correspond to the
formula 5
R O
- 15 H2C=C-C-O-R -X-H
,wherein X is as previously defined, R5 is selected from the ciass
consisting of hydrogen, chlorine and methyl and ethyl radicals;
~and R6 is a divalent organic radical selected from the group
consisting of lower alkylene of 1-8 carbon atoms, phenylene and
naphthylene.
The suitable hydroxy- or amine-containing materials are
exemplified by, but not limited to, such materials as hydroxy-
ethyl acrylate, hydroxyethyl methacrylate, aminoethyl methacrylate,
3-hydroxypropyl methacrylate, aminopropyl methacrylate,hydroxyhexyl
acrylate, t-butylaminoethyl methacrylate, hydroxyoctyl methacry-
late, and the monoacrylate or monomethacrylate esters of bisphenol-
`A and bisphenol-B and their fully hydrogenated derivatives, cyclo-
hexyl diol, and the like.
- 8 -
~o9~
The reaction may be accomplished in the presence or
absence of diluents. Preferably, diluents which include the
hydrocarbons, such as aliphatic, cycloaliphatic and aromatic
hydrocarbons, for example, benzene, toluene, cyclohexane, hexane,
- heptane, and the like, are employed, but other diluents, such
as methyl isobutyl ketone, diamyl ketone, methyl methacrylate,
isobutyl methacrylate, lauryl methacrylate, isobornyl metha-
crylate, and cyclohexyl methacrylate can also be beneficially
utilized, if desired, especially where complete compatibility
with the sealant system is desired. Mixtures of diluents may
also be used.
The temperature employed in the reaction may also
vary over a wide range. Where the components are combined in
approximately chemical equivalent amounts, useful temperatures
may vary from room temperature or below, e.g., 10C to 15C,
up to and including temperatures of 100C to 180C. Where
reacting the simpler isocyanate adducts, the components are
preferably combined at or near room temperature, such as
temperatures ranging from 20C to 30C. At the lower reaction
temperatures, use of a catalyst is preferred. When reacting
the higher molecular weight isocyanate adducts, higher
temperatures a-re preferred, e.g., about 40C to about 150C.
; It will be recognized that the acrylate-terminated
adducts of this invention can be prepared by processes other
than that described above. Thus, for instance, the polyisocyanate
compound can be reacted with a suitable hydroxyacrylate and this
adduct reacted with a suitable methylene ether polymer having the
necessary reactive hydrogen.
The fully-prepared monomeric prepolymers of this
invention correspond to the formula
R50
~CH2=C-C-O-R I Dd Ii3z
_g_
lV!~138~
wherein R5 and R6 are as previously defined; I is a
polyisocyanate radical; D is an aromatic, heterocyclic
or cycloaliphatic polyol or polyamine radical, preferably
a diol, and more preferably a diol of a cycloaliphatic
compound; Z is a polymeric or copolymeric methylene ether
polyol radical as already described; z is an integer cor-
responding to the valency of Z; d is ether 1 or 0 and i is
0 when d is 0, and otherwise is equal to one less than the
number of reactive hydrogen atoms of D. As used herein,
an asterisk (*) indicates a urethane (-NH-COO-) or ureide
(-NH-CO-NH-) bond.
The prepolymer described above cures to a hard, tough
resin via a free-radical mechanism using any of a wide
variety of known peroxy initiators. Illustrative of
such initiators are the diacyl peroxides such as benzoyl
peroxide; dialkyl peroxides such as di-tert.-butyl
peroxide; ketone peroxides such as methylethyl ketone
peroxide; and peresters which readily hydrolyze, e.g.,
tert.-butyl peracetate, tert.-butyl perbenzoate,
20 di-tert.-butyl diperphthalate, etc. A particularly
useful class of peroxy initiators are the organic hydro-
peroxides such as cumeme hydroperoxide, methylethylketone -
hydroperoxide, tert.-butyl hydroperoxide, etc. Of these,
cumene hydroperoxide is especially preferred. The initi-
ators should be used at a concentration of about 0.01
percent to about 10 percent by weight of the total formu-
lation, preferably about 0.1 percent to about 5 percent
by weight. Another useful class of initiators comprises
carbonyl-containing ultraviolet-activated free-radical
generators, such as acetophenone, benzophenone, and the
benzoin ethers. Suitable UV initiators are disclosed in
~ our Canadian Patent No. 1,009,792 issued on May 3, 1977.
; Initiator mixtures may also be used.
tr j ~ 10 --
10913~
.,
It will also be understood that the curable composition
of this invention can also be formulated as a two-part composition.
In such a case, the initiator or one of a combination of initia-
tors can comprise a second part which is combined with the first,
monomeric, part at the point of use. Thus, the monomer can be
applied to one surface to be joined, the initiator can be applied
to a second surface, and the two surfaces then joined. Similarly,
an accelerator, such as mentioned below, can be applied separately
as a second part to one of the surfaces to be joined, e.g., as
a "primer ~
It may be desirable to accelerate the cure polymerization
by application of moderate amounts of heat, e.g., 50C to 150~C.
At temperatures above about 125C, cure will typically be
complete within about 10 minutes or less.
The prepolymers of this invention can be formulated into
room temperature-curing anaerobic adhesives and sealants. Formu-
lations of this type are well described in the art, e.g., USP
3,043,820 to Krieble, among others, utilizing the hydroperoxide
class of initiators. Such anaerobic formulations may also
advantageously include polymerization accelerators such as organic
imides (e.g., benzoic sulfimide) and primary, secondary or
tertiary amines, and inhibitors or stabilizers of the quinone
or hydroquinone families. The accelerators are generally em-
ployed in concentrations of less than 10 percent by weight, and
the inhibitors in concentrations of about 10 to 1,000 parts
per million. When prepared as anaerobic formulations, the
compositions of this invention have the advantage of long-term
stability and the ability to cure at room temperature upon
exclusion of oxygen, as between the mating threads of a nut
and bolt or the juxtaposed surfaces of a bearing and shaft.
The anaerobic cure speed can be enhanced by application of
moderate heat, e.g., up to about 150C.
.~ --11--
iO~313~
The adhesive and sealant formulations of this
invention may be prepared, if desired, with reactive
diluents, and mixtures thereof, which are capable of
copolymerizing with the instant prepolymers. Typical
of such diluents are the hydroxyalkyl acrylates and
diacrylates such as hydroxyethyl acrylate, hydroxypropyl
acrylate, and the corresponding methacrylate compounds,
including cyclohexyl methacrylate, methyl methacrylate,
isobornyl methacrylate, lauryl methacrylate, triethylene
glycol dimethylacrylate, isobutyl methacrylate and
tetrahydrofurfuryl methacrylate. Other unsaturated
reactive diluents, such as styrene and acrylonitrile,
can also be used. When used, the concentration of such
diluents should be less than about 60 percent by weight,
and preferably about 40 to about 10 percent.
One of the significant advantages of the prepolymers
of this invention is their exceptional ability to cure --
through large gaps, e.g., up to about 85 mils. This
behavior may be enhanced by application of moderate heat.
Preferably, however, it is enhanced by use of any of
the primers known for anaerobic systems, such as those
disclosed in USP 3,625,930 to Toback, et al., and par-
- ticularly those of the thiourea type disclosed in our
USP 3,970,505 issued on July 20, 1976. Such primers are
advantageously applied as a spray from dilute solvent
solution to either or both surfaces to be joined.
The following examples provide specific illustrations
of various aspects of the present invention and are in no
way limitations on it.
EXAMPLE I
A nitrogen-swept 4-necked resin kettle equipped with a
stain-less steel stirrer, nitrogen inlet tube, thermometer,
- 12 -
'- `
~"
109i3b~
condenser, and entrance port, was heated to approximately
65C and charged with the following: 76.5 grams of
methylene-bis-phenylisocyanate (MDI) and a solution of
43.0 grams of triethyleneglycol dimethacrylate (TRIEGMA)
and 200 ppm of a quinone stabilizer. The mixture was
heated to about 60-65C and 95.5 grams of a 625 molecular
weight polytetramethylene ether glycol (PTME) (Polymeg
650,0H~=179.9, Trade Mark, The Quaker Oats Company,
Chicago, Illinois) was added over a 2-3 hour period.
The temperature was maintained in the 60-70C range.
A diluent solution of 20.0 grams TRIEGMA and 200 ppm
quinone stabilizer was gradually added to maintain a fluid
reaction medium. Approximately 1 1/2 hours after comple-
- tion of the glycol addition a sample was removed for NCO
analysis. The percentage of NCO for the theoretical
MDI-capped Polymeg (Trade Mark) product (abbreviated MDI*
[Polymeg 650]*MDI - Trade Mark), dissolved in the amount
diluent used, is 5.39% ("A" stage). (As used in these
examples, asterisks represent urethane bonds). A
;~ 20 dibutylamine titration procedure yielded a titer of
5.23%. After removal of the sample for NCO analysis,
61.5 grams of 96~ hydroxypropyl methacrylate (HPMA) was
added over a 10 minute period to the reaction mixture.
Heating was continued for another 2 hours with the tem-
perature maintained at 60-70C. The resultant solution
contained approximately 72% concentration of urethane -
dimethacrylate structures corresponding to the general
formula (HPMA*MDI)2*[PTME-650].
,....
EXAMPLE 2
To a nitrogen swept, heated (about 75C) resin
kettle, equipped as described in Example 1, was charged
- 13 -
,
' ~ ' ' '
l~i3~'~
50.0 grams of MDI followed by a solution of 35.0 grams of
TRIEGMA and 200 ppm of a quinone stabilizer. The mixture
was heated to 70-75C and 96.2 grams of a 960 molecular
weight polytetramethylene ether glycol (Polymeg
1000,0H#=116.6, Trade Mark - The Quaker Oats Co.), heated
to approximately 60C, was added over a 3-3 1/2 hour
period. The reaction
':
,~,
, ,,
':
`:~
- 13a -
' iO~138~
-~ temperature was maintained at 65-75C and heating was continued
for approximately one hour after completion of the glycol addition.
A diluent solution of 15.8 grams TRIEGMA and 200 ppm of a quinone
stabilizer was gradually added to maintain a fluid reaction
medium. Approximately 1/2 hour after completion of the glycol
addition, a sample was removed for NCO analysis and found to be
the desired MDI* [PTME-1000~* MDI prepolymer. The theoretical
percentage of NCO for the prepolymer (including solvent) was
4.19%; the titration yielded a titer of 4.21~. Hydroxypropyl
methacrylate (96%, 42.6 grams) was added over a 10-minute period
and heating was continued for another 1 1/2 hours at 65-75C.
The resultant solution contained approximately 72% concentration
of urethane dimethacrylate structures corresponding to the general
formula (HPMA*MDI)2*[PTME-1000].
EXAMPLE 3
To a nitrogen swept, heated (60C) resin kettle,
equipped as described in Example 1, was charged 39.2 grams of
MDI followed by a solution of 44.5 grams of TRIEGMA and 200 ppm
- of a quinone stabilizer. At approximately 60C, 154.1 grams of
a 1960 molecular weight polytetramethylene ether glycol (polymeg
2000, OH# = 57.1, Trade Mark, The Quaker Oats Co.) was added to
the heated MDI~solution (60C) over a three hour period. The
temperature of the reaction mixture was maintained at 65-75C.
After completion of the glycol addition, heating was continued
for an additional hour. A solution of 20.3 grams of ~RIEGMA
and 200 ppm of a quinone stabilizer was gradually added to
maintain a fluid reaction medium. Finally, 39.1 grams of a
96~ hydroxypropyl methacrylate was added and further heating at
60-65C was maintained for another 2 hours. The resultant
solution contained approximately 72~ concentration of urethane
dimethacrylate structures corresponding to the general formula
(HPMA*MDI)2* [PTME-2000].
-14-
1091384
EXAMPLE 4
To a nitrogen swept resin kettle, equipped as described
in Example 1, was charged 69.6 grams of toluene diisocyanate (TDI)
(80% 2,4-/20% 2,6-). The TDI was heated to approximately 95-
100C. Thirty-six grams of hydrogenated bisphenol-A (HBPA) was
added slowly in 2 hours. Fifteen minutes after the HBPA addition
was completed, a solution of 60 grams TRIEGMA and 300 ppm of a
quinone stabilizer was added slowly over a 10 minute period.
Fifteen minutes later, addition of 12.0 grams HBPA in 4-6 portions
was performed. Fifteen minutes after all the HBPA was in (total,
48.0 grams), the bath temperature was lowered such that the
reaction temperature was at 60-65C. The reaction mixture con-
sisted of toluene diisocyanate capped-HBPA prepolymer(s) (abbre-
viated TDI*HBPA*TDI) dissolved in TRIEGMA.
To the reaction solution was added 62.1 grams of a
Polymeg (Trade Mark) 650 glycol over a 1 1/2 hour period. The
reaction solution was maintained at 60-65C and heating and
stirring were continued for approximately one hour after com-
pletion of the glycol addition. The reaction mixture consisted
of TDI*HBPA*TDI capped Polymeg 650 (Trade Mark) prepolymer(s)
(abbreviated (TDI*~IBPA*TDI)2*[PTME-650]) dissolved in TRIEGMA.
A solution of 43.3 grams of 96% hydroxypropyl methacrylate, 1.8
grams TRIEGMA, and 100 ppm of a quinone stabilizer was added and
the reaction solution was maintained at 65-70C for approximately
1 1/2 hours. The resultant solution contained approximately 72~
concentration of urethane dimethacrylate structures corresponding
., ~
; to the general formuIa (HPMA(TDI*HBPA*TDI)2* [PTME-650].
,.~
-15-
iO9138~
EXAMPLE 5
To a nitrogen swept resin kettle, equipped as described
in Example 1, was charged 69.6 grams of TDI. The TDI was heated to
approximately 95C. Thirty-six grams of HBPA was added slowly
in 1 1/2 hours. Fifteen minutes after the HBPA additions were
completed, a preheated (about 50C) solution of 45.0 grams of
TRIEGMA and 150 ppm of a quinone stabilizer was added over a 10-
minute period. When the reaction temperature reached 95C, add-
ition of 12.0 grams of HBPA in 4-6 portions was performed.
Fifteen minutes after the completion of HBPA additions, the bath
temperature was lowered such that the reaction temperature dropped
to 60-65C. To the reaction solution was added 96.2 grams of a
polytetramethylene ether glycol (Polymeg 1000 - Trade Mark) in
approximately 2 hours. Heating and stirring were continued at
64-69C. A sample for NCO analysis was removedone-half hour
after completion of the glycol addition. A titer of 3.35% NCO
(vs 3.22% theoretical) was obtained for the reaction solution.
Apparently, the desired TDI*HBPA*TDI-capped ether prepolymer(s)
was formed (abbreviated (TDI*HBPA* TDI)2*[PTME-1000]). A
diluent solution of 36.4 grams of TRIEGMA and 150 ppm of a
' quinone stabilizer was added to maintain a fluid reaction medium.
Finally, 48.0 grams of 96~ hydroxypropyl methacrylate was added
to cap the prepolymer ends with methacrylate functionality.
The resultant solution contained approximately 70~ concentration
of urethane dimethacrylate structures corresponding to the general
formula (HPMA*TDI*HBPA*TDI)2*[PTME-1000].
EXAMPLE 6
To a nitrogen swept resin kettle, equipped as described
in Example 1, was charged 34.8 grams TDI. The TDI was heated
to 100C. Eighteen grams of HBPA was added slowly in 1 1/4 hours.
-16-
~ i3~3qL
Eifteen minutes after the HBPA addition was completed, a pre~
heated (about 50C) solution of 35.0 grams of TRIEGMA and 150 ppm
of a quinone stabilizer was added over a 5-minute period. Fifteen
minutes later, addition of 6.0 grams of HBPA in 3-5 portions was
performed. Upon completion of the HBPA additions, the bath
temperature was lowered such that the reaction temperature settled
to 60-65C. To the reaction solution was added 98-2 grams of a
2000 molecular weight polytetramethylene ether glycol(Polymeg
2000) within 2 1/4 hours. Heating and stirring were continued
for an additional hour at 60-70C. A diluent solution of 15.2
grams of TRIEGMA and 150 ppm of a quinone- stabilizer was added to
.
maintain a fluid reaction medium. Hydroxypropyl methacrylate
(96-~, 27.4 grams) was added over a 5-minute period and heating
was continued for an additional hour at 60-65C. The resultant
solution contained approximately 72% concentration of urethane
dimethacrylate structures corresponding to the general formula
(HPMA*TDI*HBPA*TDI)2* [PTME-2000].
EXAMPLE 7
To a nitrogen swept resin kettle, equipped as described
in Example 1, was charged 52.4 grams of liquid, hydrogenated MDI
(H12-MDI, Hylene W,E.I. du Pont de Nemours and Company, Wilming-
ton, Delaware). The H12-MDI was heated to approximately 100C;
To the diisocyanate was added 10.8 grams of (CHDM) cyclohexane-
dimethanol over a 20-minute period. This was followed by the
addition of a diluent solùtion of 35.0 grams of TRIEGMA and 150
ppm of a quinone stabilizer over a 10-minute period. When ~he
temperature reached 100C, 3.6 grams of cyclohexanedimethanol was
added slowly. Approximately one-half hour later, a sample was
removed for NCO analysis. Titration revealed a titer of 8.40
NCO versus a theoretical (incl`uding solvent) titer of 8.10~.
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:~ .
,
1()91.38~
Apparently, the desired H12-MDI*CHDM*Hl~-MDI prepolymer was
achieved. The bath temperature was lowered such that the solution's
temperature settled to 60-70C. To the reaction solution was
added 98.3 grams of a 2000 molecular weight polytetramethylene
- ether glycol within 1-2 hours. Approximately one hour later,
another diluent solution was added (29.1 grams of TRIEGMA and 150
ppm stabilizer). Another sample was withdrawn for NCO anaylsis.
Titration revealed a titer of 3.55% NCO vs a theoretical of 3.62%
NCO. Again, the desired prepolymer(s) was apparently formed:
(H12-MDI*CHDM* H12-MDI)2*[PTME-2000]. Hydroxypropyl methacrylate
(96%, 44.4 grams) was added over a 10-minute period. Heating was
continued at 60-65C. The resultant solution contained approxi-
mately 70% concentration of urethane dimethacrylate structures
corresponding to the general formula (HPMA*H12-MDI*CHDM*H12-
MDI)2*[PTME-2000].
EXAMPLE 8
; :
This example illustrates a typical anaerobic adhesive
formulation utilizing any of the prepolymers, or mixtures thereof,
described above. With good stirring, add 4.6 grams of hydroxy-
20 propyl methacrylate to 79 grams of the prepolymer resin product
solution (70-75 percent solids). A slurry of 0.38 gram saccharine
in 3.8 grams of triethyleneglycol dimethacrylate is then stirred
in. Subsequently, 5.6 grams of acrylic acid (adhesion enhancer)
and 2.8 grams of cumene hydroperoxide (CHP) are added and stirring
is continued for about 1 hour. Minor amounts of stabilizers,
accelerators, thickeners, plasticizers, and the like, may be
added, as desired, as is known in the art.
1091384
EXAMPLE 9
Anaerobic adhesive formulation were prepared similar to
Example 8 using the prepolymers of Example 1-7.
TABLE I
Prepolymer General Structure
A (HPMA*MDI?2*[PTME-650]
B (HPMA*MDI)2*[PTME-1000]
C (HPMA*MDI)2*[PTME-2000]
D (HPMA*TDI*HBPA*TDI)2*[PTME-650]
E (HPMA*TDI*HBPA*TDI)2*[PTME-1000]
F (HPMA*TDI*HBPA*TDl)2*~PTME-2000]
G (HPMA*H12-MDI*CHDM*H12-MDI)2*[P~ME-2000]
The typical strength properties for these adhesive
formulations are reported in Table II, below. Tensile strength
measurements were performed according to ASTM D-2095-72. Simply
described, this test involves adhering together two steel rods
by butt joining their respective ends. The opposite rod ends
are then pulled with a measuring device such as an Instron
Tester, and the tensile strength of the bond is measured. The
tensile lap shear test was performed according to ASTM D-1002-65.
This test involves adhering together overlapping surfaces of
two steel test strips. The ends of the so-assembled specimens
are pulled with a measuring device such as an Instron Tester,
and the tensile shear strength of the bond is measured.
Compressive shear, tested according to military specification
MIL-R-46082A (MR), measures the ability of an adhesive to retain
a sleeve or bearing on a shaft. The test involves adhering a
cylindrical "pin" within the bore of a mating collar. The force
required to press the pin from the collar in then measured on
an Instron Tester or equivalent. Impact strength was tested
according to ASTM D-950-72. This test involves a steel block
mated to another steel block with adhesive
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10913~
and then struck by a swinging pendulum device, such as a BaldwinImpact Tester. The impact force required to separate the blocks
is measured. Heat (200F) was used, for convenience, to accele-
rate cure in all tests; for one hour in the tensile and compres-
sive shear tests, and for 1 1/2 hours in the impact test.
TABLE II
Tensile Lap Impact
Prepolymer- Shear, psi Strength,
Adhesive Tensile, (Steel laps, Compressive ft. lbs./
Formulation psi sand blasted~ Shear, psi sq. in.
A 7440 4390 3395 13.1
B 5435 3535 2660 5.2
C 3595 2670 2680 7.0
D 7390 4100 5345 13.2
E 9215 4150 4220 13.0
F 4650 3365 3325 10.2
EXAMPLE 10
The corresponding formulation of prepolymer A was
tested for its ability to retain useful levels of strength after
lengthy exposure to high temperatures. The excellent strength
retention of this formulation is shown in Table III. The
strength test used was the compressive shear test already des-
cribed. The specimens were aged at 400F for the number of weeks
shown, then divided into two groups, which were tested at room
temperature and 400F, respectively.
TABLE III
Heat Aging Period, Compressive Shear Strength, psi
Weeks Room Temperature 400F
0 3160 275
3.0 1725
9.5 1770 280
. .
. ~ :
': -
-20-
.
lV~13~3~
EXAMPLE 11
Another significant merit of the present prepolymers
when formulated as adhesives is their ability to cure through
; relatively large gaps, e.g., 20 mils or more, to form structurally
strong bonds with very high impact strengths. Table IV illustrates
typical tensile shears (room temperature cured on sand-blasted
steel surfaces primed with a tetramethyl thiourea activator
known to the art) and impact strengths (cured either by the above
activator at room temperature or heat cured for one and one-half
hour at 200F)
TABLE IV
- Impact Strength ft.lbs./ sq. in.
Tensile Shear, 20-mil gap 20-mil gap 55-mil gap
Prepolymer psi, 20-mil gap (primer) (heat cured) (heat)
A 1645 13.4 13.4 6.4*
C 1195 10.7
E 2405 13.3 12.1
F 1195 15.7 12.5 11.2
G 9.7 10.1 3.6
; * with 6~ inorganic as thickener to confer thixotropic properties
EXAMPLE 12
A further distinct advantage of the present prepolymers
is their excellent strengths under cryogenic conditions. This
is illustrated in Table V, which presents the exceptionally high
impact strength, even at large gaps, found for the adhesive
formulations, as in ~xampIe 9, of representative materials at
low test temperatures. Heat (200F, 1 1/2 hours) was used, for
convenience, to accelerate cure in all samples. The blocks
- were then cooled to the appropriate temperature and promptly
tested; otherwise, the impact test procedure was as previously
described.
,~,.
-21-
. .
. .
.
10~138~
-~ TABLE V
Impact Strength, Ft. lbs/sq. in.
Room
Prepolymer Temperature 0C -40C -80C
A0 mils 16.720.0 20.1 18.3
20 mils 13.413.9 5.8* 8.1
E0 mils 13.425.8 23.7
20 mils 12.111.5 2.7
F0 mils 10.213.3 18.5 18.7
20 mils 14.615.1 11.6 8.0
* heat cured 45 minutes instead of 90 minutes
EXAMPLE 13
A curable formulation was prepared using prepolymer -
A (Table I) similar to the procedure of Example 8, except that
5% (based on total formulation weight) of benzophenone was
substituted for the CHP and saccharine. A 2-5 mil thick film
of the formulation was spread on a piece of glass and exposed
to ultraviolet radiation. The UV source was a 400-watt mercury
vapor bulb housed in a "Porta-Cure 400" (Trade Mark) lamp, both
bulb and lamp manufactured by American Ultraviolet Co. The UV
source was adjusted to provide 6000 microwatts of radiation
intensity at the film After 11-13 minutes of exposure, the
formulation had cured to a hard, dry film.
The same formulation was used to assemble a lap shear
test specimen, except that glass strips were used in place of
steel. The specimen was exposed to UV radiation of 6,000 micro-
watts at the bond line. In about 35 seconds, the glass strips
had become fixtured (could not be moved by hand relative to
each other).
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~`
10913~
EXAMPLE 14
- ~ An adhesive formulation was prepared using prepolymer
E (Table I) according to the procedure of Example 8, except that
3-5% (based in total formulation weight) of benzoyl peroxide
was substituted ~or the CHP and saccharine. A 2-5 mil thick
~ film of the formulation was spread on a steel plate and placed
in a 200F oven for 1 1~2 hours, then cooled to room temperature.
; The formulation cured to a dry, durable film.
A tensile lap shear test (as previously described)
was performed. A heat cure was applied ~200F, 1 hour), resulting
in a bond strength of 3400 psi.
.,
. .
:,
~ -23-
