U.S. patent application number 10/252174 was filed with the patent office on 2003-07-31 for compositions for making ene-thiol elastomers.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Gross, Kathleen B., Schultz, William J..
Application Number | 20030144442 10/252174 |
Document ID | / |
Family ID | 22461362 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030144442 |
Kind Code |
A1 |
Gross, Kathleen B. ; et
al. |
July 31, 2003 |
Compositions for making ene-thiol elastomers
Abstract
In one aspect, the invention provides ene-thiol elastomers
comprising the reaction product of a polythiol free of hydrophilic
groups and having at least two thiol groups and an aromatic,
heterocyclic, aliphatic, or cycloaliphatic polyene having at least
two reactive unsaturated carbon to carbon bonds. In another aspect,
the invention provides ene-thiol elastomer comprising the reaction
product of (a) a thiol terminated oligomer comprising the reaction
product of a polythiol having two thiol groups and a first polyene
or mixture of polyenes having two reactive unsaturated carbon to
carbon bonds; and (b) a second polyene or a mixture of polyenes
having at least 5 percent functional equivalents of unsaturated
carbon to carbon bonds from polyenes having at least three
unsaturated carbon to carbon bonds. The ene-thiol elastomers of the
invention have a weight increase of not more than 4 weight percent
in 15 days at a temperature of 22.degree. C. when immersed in a
solution of 96 parts by weight water and 4 parts by weight
n-butanol and/or a water vapor transmission rate of less than 50
g-mm/m.sup.2-day at 40.degree. C. according to ASTM D814.
Inventors: |
Gross, Kathleen B.;
(Woodbury, MN) ; Schultz, William J.; (Vadnais
Heights, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
22461362 |
Appl. No.: |
10/252174 |
Filed: |
September 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10252174 |
Sep 23, 2002 |
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09567944 |
May 10, 2000 |
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6479622 |
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60134012 |
May 10, 1999 |
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Current U.S.
Class: |
526/286 |
Current CPC
Class: |
C08G 75/12 20130101;
H05K 3/285 20130101; C08G 75/045 20130101 |
Class at
Publication: |
526/286 |
International
Class: |
C08F 012/30 |
Claims
What is claimed is:
1. An ene-thiol elastomer comprising the reaction product of: (a)
an unsaturated carbon to carbon bond terminated oligomer comprising
the reaction product of a first polythiol having two thiol groups
and a polyene or mixture of polyenes having two reactive
unsaturated carbon to carbon bonds; and (b) a second polythiol or
mixture of polythiols, having at least 5 percent functional thiol
equivalents from polythiols having at least three thiol groups,
wherein the ene-thiol elastomer shows a weight increase of not more
than 4 weight percent in 15 days at a temperature of 22.degree. C.
when immersed in a solution of 96 parts by weight water and 4 parts
by weight n-butanol.
2. The elastomer of claim 1 wherein said polyene comprises allyl,
vinyl, allyl ether, allyl ester, vinyl ether, styryl, cycloalkenyl,
or (meth)acryl compounds, or combinations thereof.
3. The elastomer of claim 1 wherein the polyene is
triallyl-1,3,5-triazine- -2,4,6-trione;
2,4,6-triallyloxy-1,3,5-triazine; 1,4-cyclohexanedimethanol divinyl
ether; 4-vinyl-1-cyclohexene; 1,5-cyclooctadiene; diallyl
phthalate; or a combination thereof.
4. The elastomer of claim 1 wherein the polyene is a mixture of a
polyene having two reactive unsaturated carbon to carbon bonds and
a polyene having three reactive unsaturated carbon to carbon
bonds.
5. The elastomer of claim 1 wherein the heterocyclic polyene is
triallyl-1,3,5-triazine-2,4,6-trione;
2,4,6-triallyloxy-1,3,5-triazine; or a combination thereof.
6. The elastomer of claim 1 wherein the polythiol has the formula:
4where m=2-12, n=2-12, q=0-4, where m and n can be the same or
different; or the formula H--S--R--S--H, where R=C.sub.5-C.sub.8
cycloaliphatic radical.
7. The elastomer of claim 1 wherein the polythiol is
dimercaptodiethyl sulfide; 1,6-hexanedithiol;
1,8-dimercapto-3,6-dithiaoctane; or a combination thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 09/567,944, filed May 10, 2000, now allowed, which claims the
benefit of U.S. Provisional Application No. 60/134,012, filed May
10, 1999.
FIELD OF THE INVENTION
[0002] The invention relates to curable compositions used for
making ene-thiol elastomers and cured ene-thiol elastomers made
therefrom.
BACKGROUND OF THE INVENTION
[0003] Electronic circuits must be protected from exposure to harsh
corrosive environments to maintain the performance of the
electronic device. Many electronic circuits are used in
environments where they are exposed to corrosive liquids. For
example, adhesives and encapsulants used to assemble ink jet
cartridges must protect the flexible circuit that controls the ink
jet head from exposure to corrosive inks. These adhesives and
encapsulants experience long term exposure to very corrosive inks.
If the adhesive or encapsulant degrade or excessively swell, the
ink contacts and corrodes the circuit.
[0004] Thermosetting resins, frequently epoxy resins, are used to
protect circuits from corrosive environments. Epoxy resins have
several characteristics that limit their ability to perform well.
Traces of chloride ion, which are frequently present in epoxy
resins, promote the corrosion of circuits. Epoxy networks are
somewhat hydrophilic and swell in aqueous environments because of
the secondary alcohols produced in the curing reaction. Epoxy
networks are frequently difficult to fully cure in the
time/temperature constraints of electronic manufacturing processes.
Unreacted epoxy groups are prone to hydrolysis, forming glycols,
which further decreases the water resistance of the network. These
epoxy characteristics limit their use as adhesives and encapsulants
in corrosive environments.
[0005] Many combinations of polyfunctional olefins and mercaptans
have been used to prepare ene-thiol networks. While many monomers
have very attractive process characteristics (low viscosity and
rapid UV curing), they do not provide networks having the requisite
environmental resistance to withstand highly corrosive aqueous
environments. Polyether dimercaptans are frequently used in
ene-thiol compositions. These monomers introduce hydrophilic units
to the cured network, resulting in excessive swelling in aqueous
environments. Multifunctional mercaptoacetates and propionates are
other commonly used thiol monomers. In addition to their
hydrophilic character, the ester linkage introduces a site for
hydrolysis and network degradation.
SUMMARY OF THE INVENTION
[0006] In one aspect, the invention provides a curable composition
for making an ene-thiol elastomer comprising a mixture of a
polythiol, or a mixture of polythiols, having at least two thiol
groups and free of hydrophilic groups, and an aromatic,
heterocyclic, aliphatic, or cycloaliphatic polyene having at least
two reactive unsaturated carbon to carbon bonds, wherein the
composition in cured form, when immersed in a solution of 96 parts
by weight water and 4 parts by weight n-butanol, shows a weight
increase of not more than 4 weight percent, preferably, not more
than 3 weight percent, and more preferably, not more than 2.5
weight percent in 15 days at a temperature of 22.degree. C.
[0007] In another aspect, the invention provides a ene-thiol
elastomer comprising the reaction product of a composition
comprising a mixture of a polythiol having at least two thiol
groups and free of hydrophilic groups and an aromatic,
heterocyclic, aliphatic, or cycloaliphatic polyene having at least
two reactive unsaturated carbon to carbon bonds, wherein the
ene-thiol elastomer, when immersed in a solution of 96 parts by
weight water and 4 parts by weight butyl alcohol, shows a weight
increase of not more than 4 weight percent, preferably, not more
than 3 weight percent, and more preferably, not more than 2.5
weight percent in 15 days at a temperature of 22.degree. C.
[0008] In another aspect, the invention provides a curable
composition for making an ene-thiol elastomer comprising a mixture
of (a) a thiol terminated oligomer comprising the reaction product
of a polythiol having two thiol groups and a first polyene or
mixture of polyenes having two reactive unsaturated carbon to
carbon bonds, and (b) a second polyene or a mixture of polyenes
having at least 5 percent functional equivalents of unsaturated
carbon to carbon bonds from polyenes having at least three
unsaturated carbon to carbon bonds, wherein the composition in
cured form, when immersed in a solution of 96 parts by weight water
and 4 parts by weight n-butanol, shows a weight increase of not
more than 4 weight percent, preferably, not more than 3 weight
percent, and more preferably, not more than 2.5 weight percent in
15 days at a temperature of 22.degree. C.
[0009] Generally, not more than 50 weight percent, preferably, not
more than 30 weight percent, more preferably, not more than 20
weight percent, and even more preferably, none of the polythiol
used to make the oligomer has hydrophilic groups. The first and
second polyenes or mixtures of polyenes may be the same or
different. Preferred first polyenes include divinyl ethers, and
cyclic polyenes. Preferred polythiols include dimercaptodiethyl
sulfide, 1,6-hexanedithiol, and 1,8-dimercapto-3,6-dith-
iaoctane.
[0010] In another aspect, the invention provides a ene-thiol
elastomer comprising the reaction product of a composition
comprising the reaction product of (a) a thiol terminated oligomer
comprising the reaction product of a polythiol having two thiol
groups and a first polyene or mixture of polyenes having two
reactive unsaturated carbon to carbon bonds and (b) a second
polyene or a mixture of polyenes having at least 5 percent
functional equivalents of unsaturated carbon to carbon bonds from
polyenes having at least three unsaturated carbon to carbon bonds,
wherein the composition in cured form, when immersed in a solution
of 96 parts by weight water and 4 parts by weight n-butanol, shows
a weight increase of not more than 4 weight percent, preferably,
not more than 3 weight percent, and more preferably, not more than
2.5 weight percent in 15 days at a temperature of 22.degree. C.
[0011] Generally, not more than 50 weight percent, preferably, not
more than 30 weight percent, more preferably, not more than 20
weight percent, and even more preferably, none of the polythiol
used to make the oligomer has hydrophilic groups. The first and
second polyenes or mixtures of polyenes may be the same or
different. Preferred first polyenes include divinyl ethers, and
cyclic polyenes. Preferred polythiols include dimercaptodiethyl
sulfide, 1,6-hexanedithiol, and 1,8-dimercapto-3,6-dith-
iaoctane.
[0012] In another aspect, the invention provides ene-thiol
elastomers comprising the reaction product of a composition
comprising a mixture of a polythiol having at least two thiol
groups and free of hydrophilic groups and an aromatic,
heterocyclic, aliphatic, or cycloaliphatic polyene having at least
two reactive unsaturated carbon to carbon bonds, wherein the
ene-thiol elastomers have a water vapor transmission rate of less
than 50, preferably less than 30, more preferably, less than 20
g-mm/m.sup.2-day at 40.degree. C. according to ASTM D814.
[0013] In another aspect, the invention provides ene-thiol
elastomers comprising the reaction product of a composition
comprising the reaction product of (a) a thiol terminated oligomer
comprising the reaction product of a polythiol having two thiol
groups and a first polyene or mixture of polyenes having two
reactive unsaturated carbon to carbon bonds and (b) a second
polyene or a mixture of polyenes having at least 5 percent
functional equivalents of unsaturated carbon to carbon bonds from
polyenes having at least three unsaturated carbon to carbon bonds,
wherein the ene-thiol elastomers have a water vapor transmission
rate of less than 50, preferably less than 30, more preferably,
less than 20 g-mm/m.sup.2-day at 40.degree. C. according to ASTM
D814.
[0014] In another aspect, the invention provides an ene-thiol
elastomer comprising the reaction product of (a) an unsaturated
carbon to carbon bond terminated oligomer comprising the reaction
product of a first polythiol having two thiol groups and a polyene
or mixture of polyenes having two reactive unsaturated carbon to
carbon bonds; and (b) a second polythiol or mixture of polythiols
having at least 5 percent functional thiol equivalents from
polythiols having at least three thiol groups, wherein the
ene-thiol elastomer shows a weight increase of not more than 4
weight percent in 15 days at a temperature of 22.degree. C. when
immersed in a solution of 96 parts by weight water and 4 parts by
weight n-butanol.
[0015] In other aspects, the invention provides a method of making
the above ene-thiol elastomers, and an article of manufacture
comprising electrical or electronic components encapsulated in a
ene-thiol elastomer of the invention.
[0016] The compositions of the invention preferably contain a free
radical initiator and more preferably, a photoinitiator.
[0017] As used herein, the term "polythiols" refers to simple or
complex organic compounds which are substantially free of disulfide
linkages and have a multiplicity of pendant or terminally
positioned --SH functional groups per molecule.
[0018] As used herein, the term "free of hydrophilic groups" when
used to describe polythiols means polythiols devoid of any ether,
ester, hydroxyl, carbonyl, carboxylic acid, sulfonic acid linkages
or groups within or pendant from the polythiol molecule.
[0019] As used herein, the term "polyene" refers to simple or
complex species of alkenes having at least two reactive unsaturated
carbon to carbon bonds per molecule.
[0020] As used herein, the terms "di functional", "trifunctional",
and "tetrafunctional" when used to describe polythiols and polyenes
means polythiols having two, three, and four thiol groups and
polyenes having two, three, and four reactive unsaturated carbon to
carbon bonds.
[0021] The compositions of the invention are generally low
viscosity liquids that can be uniformly coated onto flexible
circuitry and rapidly cured by actinic radiation. The resulting
ene-thiol elastomers are tough, flexible, and resist swelling or
chemical degradation by water and corrosive components of inks.
[0022] One of the unique properties of the ene-thiol elastomers of
the invention is the combination of flexibility with resistance to
swelling and degradation by water and corrosive environments.
Brittle thermoset resins, such as conventional epoxies, may provide
reasonable resistance to swelling by corrosive components of inks
but are prone to cracking when used on a flexible circuit. The
resulting cracks then provide a path for the corrosive liquid to
penetrate the coating and corrode the substrate. Low Tg epoxies,
acrylates, urethanes or other elastomeric thermosetting resins,
which are flexible and resist cracking, are generally prone to
degradation by these corrosive liquids. The ene-thiol elastomers of
the invention provide the swelling resistance of brittle glassy
epoxy resins with elastomeric flexibility.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The polythiols of the invention have at least two thiol
groups and are free of hydrophilic groups. Useful polythiols are
also substantially free of disulfide linkages that would impart
chemical and/or thermal instability to the crosslinked or cured
network. The polythiols may be aliphatic or aromatic and may be
monomeric or polymeric. Useful polythiols have the formula: 1
[0024] where m=2-12, n=2-12, q=0-4, where m and n can be the same
or different; or the formula H--S--R--S--H, where R=C.sub.5-C.sub.8
cycloaliphatic radical.
[0025] The use of di-, tri-, and tetra-functional polythiols is
also contemplated in the present invention.
[0026] Specific examples of useful polythiols include
dimercaptodiethyl sulfide; 1,6-hexanedithiol;
1,8-dimercapto-3,6-dithiaoctane; propane-1,2,3-trithiol; 1,2-bis
[(2-mercaptoethyl)thio]-3-mercaptopropane- ;
tetrakis(7-mercapto-2,5-dithiaheptyl)methane; and trithiocyanuric
acid. The polythiols may be used alone or in combination with one
another.
[0027] When using polythiols having two thiol groups, useful
polyenes of the invention may be characterized by mixtures of those
materials having at least 5 percent functional equivalents of
unsaturated carbon to carbon bonds contributed by polyenes having
at least three unsaturated carbon to carbon bonds. Preferred
polyenes are heterocyclic, aliphatic, or cycloaliphatic diene,
allyl ether, allyl ester, vinyl ether, styryl, (meth)acryl, allyl
or vinyl compounds having at least two or three reactive
unsaturated carbon to carbon bonds per molecule. Mixtures of
polyenes, each having two and three unsaturated carbon to carbon
bonds respectively, are preferred. Specific examples include
triallyl-1,3,5-triazine-2,4,6-trione;
2,4,6-triallyloxy-1,3,5-triazine; 1,4-cyclohexanedimethanol divinyl
ether; 4-vinyl-1-cyclohexene; 1,5-cyclooctadiene; and diallyl
phthalate. Combinations of useful polyenes may also be used in the
compositions of the invention. The polythiols and polyenes are
present in the compositions and elastomers of the invention in a
stoichiometric amount.
[0028] The composition of the invention may contain a free radical
initiator, preferably a UV active free radical initiator, to cure
or crosslink the composition. Useful free radical initiators which
are well known in the art and include the class of free radical
initiators are commonly referred to as "photoinitiators." A
preferred commercially available free radical initiator, also a
photoinitiator, is IRGACURE 651, available from Ciba Specialty
Chemicals, Tarrytown, N.J. Alternatively, the compositions of the
invention may also contain thermally activated free radical
initiators.
[0029] The compositions of the invention are generally made by
mixing a stoichiometric amount of one or more polythiols and one or
more polyenes in an appropriate vessel. In the case of reacting
polythiols and polyenes, each having two thiol and unsaturated
carbon to carbon bonds respectively, it may be preferable to first
form an oligomer using a sub-stoichiometric amount of polyene and
then reacting the oligomer with a polyene having at least three
unsaturated carbon to carbon bonds to form the crosslinked
elastomer. If a photoiniator is used, the components may be mixed
in the absence of actinic radiation and then stored in the dark for
extended periods of time. If desired, the compositions of the
invention may contain conventional inhibitors to prevent
spontaneous radical polymerization.
[0030] One of the advantages of first preparing an oligomer by
reacting a sub-stoichiometric amount of polyene having two
unsaturated carbon to carbon bonds with polythiol having two thiol
groups is that the oligomer, having an increased molecular weight,
may be vacuum devolatilized so to substantially reduce the
objectionable odor characteristics of polythiols. The resulting
oligomers have very low vapor pressures by virtue of their
molecular weight and have little odor, but may contain volatile
sulfur containing compounds that cause objectionable odor. The
removal of such compounds results in compositions having low odor.
Another advantage of first preparing oligomers is that such
preparation allows the use of combinations of polyenes having
different reactivities. For example, a polyene having two
unsaturated carbon to carbon bonds having low reactivity can be
used to prepare the oligomer and a mixture of polyenes having two
and three unsaturated carbon to carbon bonds having relatively high
reactivity can be used to react with the oligomer to form the
elastomer.
[0031] Alternatively, the ene-thiol elastomers of the invention may
be made using a polythiol having either three or four thiol groups
per molecule and a polyene oligomer terminated with unsaturated
carbon to carbon bonds. Such polyene oligomers can be made from the
reaction of a polyene having two unsaturated carbon to carbon bonds
and a sub-stoichiometric amount of a polythiol having two thiol
groups per molecule. Elastomers can be made by reacting the polyene
oligomer with polythiols, wherein at least 5 percent of the
functional equivalents of thiol is provided by polythiols having at
least three thiol groups per molecule.
[0032] The compositions can then be applied to the desired
substrate, for example, electrical connectors, or other electrical
components and the like, and exposed to electron beam radiation. If
the composition contains a photoinitiator, the composition may be
exposed to any form of actinic radiation, such as visible light or
UV radiation, but is preferably exposed to UVA (320 to 390 nm) or
UVV (395 to 445 nm) radiation. Generally, the amount of actinic
radiation should be sufficient to form a solid mass that is not
sticky to the touch. Generally, the amount of energy required
curing the compositions of the invention ranges from about 0.4 to
20.0 J/cm.sup.2.
Glossary
[0033] DMDS--Dimercaptodiethyl sulfide (Structure 1),
HSC.sub.2H.sub.4SC.sub.2H.sub.4SH, CAS No. 3570-55-6, available
from Itochu Specialty Chemical Inc.
[0034] DMDO--1,8-dimercapto-3,6-dioxooctane,
HSC.sub.2H.sub.4OC.sub.2H.sub- .4OC.sub.2H.sub.4SH, CAS NO.
14970-87-7, available from Itochu Specialty Chemical Inc.
[0035] EBMP--Ethylene bis(3-mercaptopropionate),
HSC.sub.2H.sub.4COOC.sub.- 2H.sub.400CC.sub.2H.sub.4SH, 7575-23-7,
available from Evans Chemetics Division of Hampshire Chemicals.
[0036] CAPCURE.RTM. 3-800--Trifunctional mercaptan terminated
liquid polymer, available from Henkel Corporation.
[0037] HDT--1,6-hexanedithiol, HSC.sub.6H.sub.12SH, CAS No.
1191-43-1, available from Aldrich Chemical Company.
[0038] IGRACURE 651-2,2-Dimethoxy-2-phenylacetophenone,
C.sub.6H.sub.5COC(OCH.sub.3).sub.2C.sub.6H.sub.5, CAS No.
24650-42-8, available from Ciba Specialty Chemicals.
[0039] TAIC--Triallyl-s-triazine-2,4,6(1H,3H,5H)-trione, (Structure
2), CAS No. 1025-15-6, available from Aldrich Chemical Company.
[0040] TAC--Triallyloxy-1,3,5-triazine, (Structure 3), CAS No.
101-37-1, available from Aldrich Chemical Company.
[0041] Rapi-Cure CHVE--1,4-cyclohexanedimethanol divinyl ether
(Structure 4), CAS No. 17351-75-6, available from International
Specialty Products.
[0042] VCH--4-vinyl-1-cyclohexene (Structure 5), CAS No. 100-40-3,
available from Aldrich Chemical Company.
[0043] COD--1,5-cyclooctadiene (Structure 6), CAS No. 111-78-4,
available from Aldrich Chemical Company.
[0044] DAP--diallyl phthalate (Structure 7), CAS No. 131-17-9,
available from Aldrich Chemical Company.
[0045] PEGDE--poly(ethylene glycol) divinyl ether (Structure 8),
CAS No. 50856-26-3, available from Aldrich Chemical Company.
[0046] AIBN--2,2'-azobisisobutronitrile, CAS No. 78-67-1, available
from Aldrich Chemical Company. It is used as a thermal free radical
initiator.
[0047] NPAL--tris(N-nitroso-N-phenylhydroxylamine)aluminum salt,
CAS No. 15305-07-4, available from First Chemical Corporation. It
is used as a radical inhibitor. 2
[0048] Oligomer Preparation
[0049] A variety of oligomers with different backbone structures
were synthesized. DMDS was chosen as a monomer to minimize the
amount of ether linkages in the backbone and maximize the number of
thioether linkages. The oligomers were prepared by the addition of
a dimercaptan to a diolefin under free radical conditions. The
molecular weight of the oligomer was controlled by reaction
stoichiometry. The reactions were carried out either thermally or
photochemically. Polymerizations carried out with less reactive
olefins such as VCH and COD were more successful using the
photochemical method.
[0050] Thermal Procedure. A dimercaptan or mixture of dimercaptans
was weighed into a flask, AIBN was added, and the flask was heated
to 65.degree. C. A diolefin was added dropwise to the dimercaptan
solution at a rate to maintain the temperature in the flask between
90-100.degree. C. After the addition, the oligomer was stirred for
4 hours, and the temperature was maintained at 75-80.degree. C. The
reaction product was checked by .sup.1H NMR and .sup.13C NMR
determine whether any olefin groups remained. If olefin was still
present in the product mixture, additional AIBN was added and the
oligomer was stirred at 75-80.degree. C. for an additional 5 hours,
when the amount of olefin remaining was determined to be less than
4 percent by .sup.1H NMR. The oligomers in Table 1 were prepared
using the thermal procedure.
[0051] Alternative Thermal Procedure. The reaction was carried out
as described above; however, 0.5 percent AIBN was dissolved into
the diolefin, and the resulting solution was added to the
dimercaptan.
1 TABLE 1 Initiator Reaction Target DMDS CHVE DAP Wt. % Time
M.sub.N Oligomer 1 100.3 g 112.7 -- 0.3% 4 hr 2800 Oligomer 2 30.37
g 25.45 -- 0.5% 4 hr 830 Oligomer 3 24.57 g -- 35.06 g 0.6% 9 hr
2800 Oligomer 4 25.20 g -- 25.24 g 0.75% 9 hr 830
[0052] Photochemical Procedure. A dimercaptan, a diolefin, and 0.5
weight percent IRGACURE 651 were weighed into a glass jar. The
contents of the jar were shaken and were irradiated for 4 hours
with two GTE 15 watt Sylvania 350 nm black light bulbs having a
power output of 1 mW/cm.sup.2. Additional IRGACURE 651 was added,
and the oligomer was heated to 80.degree. C. The oligomer was
irradiated again for several hours. The reaction was considered
complete when greater than 95 percent of the olefin groups had
reacted as judged by .sup.1H and .sup.13C NMR. The oligomers in
Table 2 were made using the photochemical procedure.
2 TABLE 2 Total Exposure Target DMDS VCH COD Initiator Time M.sub.N
Oligomer 5 39.83 g 25.41 g -- 1.3% 16 hr 2800 Oligomer 6 30.02 g
15.17 g -- 0.5% 4 hr 830 Oligomer 7 35.03 g -- 22.33 g 1.0% 12 hr
2800 Oligomer 8 40.25 g -- 21.53 g 1.2% 12 hr 1000
[0053] Oligomers 9 and 10 are described in Table 3 and contain a
combination of VCH, which contains no oxygen ether linkages, and
CHVE, which has reactive vinyl ether groups. DMDS, VCH, and
IRGACURE 651 were weighed into a glass jar. The contents were
shaken and irradiated for 4 hours with two GTE 15 watt Sylvania 350
nm black light bulbs having a power output of 1 mW/cm.sup.2. CHVE
and IRGACURE 651 were added to the resulting oligomer, and the
solution was irradiated again for 2 hours.
3 TABLE 3 Total DMDS VCH CHVE Initiator Target M.sub.N Oligomer 9
17.12 g 5.38 g 9.76 g 0.5% 2800 Oligomer 10 25.09 g 6.05 g 10.98 g
0.6% 830
[0054] Oligomers 11 and 12 are described in Table 4 and were
prepared with a mixture of DMDS and DMDO. The alternative thermal
procedure listed above was used, and 0.5 percent AIBN was the
catalyst level for each reaction. For Oligomer 11, DMDS and DMDO
were used in a 70:30 ratio, and for Oligomer 12 DMDS and DMDO were
used in a 50:50 ratio. For both oligomers, there are more sulfur
atoms than oxygen atoms in the backbone.
4 TABLE 4 DMDS DMDO CHVE Target M.sub.N Oligomer 11 9.00 g 7.62 g
17.08 g 2800 Oligomer 12 15.00 g 17.72 g 24.61 g 830
[0055] Oligomers 13-18 are described in Table 5 and contain more
oxygen atoms than sulfur atoms in the backbone and were prepared
for purposes of comparison. The alternative thermal procedure
listed above was used, and 0.5 percent AIBN was the catalyst level
for each reaction.
5 TABLE 5 DMDS DMDO CHVE PEGDE Target M.sub.N Oligomer 13 -- 16.00
g 15.01 g -- 2800 Oligomer 14 -- 15.12 g 10.29 g -- 830 Oligomer 15
16.01 g -- -- 22.16 g 2800 Oligomer 16 25.50 g -- -- 25.53 g 830
Oligomer 17 9.68 g 11.49 g -- 26.71 g 2800 Oligomer 18 12.51 g
14.78 g -- 24.57 g 830
[0056] Preparation of DMDT. DMDT, 1,8-dimercapto-3,6-dithiaoctane
(Structure 9), was prepared from 3,6-dithia-1,8-octadiol using the
method of Cooper et al. with the exception that 38 percent HCl was
used in place of 48 percent HBr in the synthesis. Wolf, R. E., Jr.;
Hartman, J. R.; Storey, J. M. E.; Foxman, B. M.; Cooper, S. R. J.
Am. Chem. Soc. 1987, 109, 4328-4335. 3
EXAMPLES
Examples 1-4
[0057] Examples 1-4 were prepared by mixing the components in the
ratios identified in Table 6. The resins were cured by placing 6
grams of the liquid mixture into a 70 mm diameter aluminum dish,
heating to 50.degree. C., and irradiating for 1 hour under two GTE
15 watt Sylvania 350 nm black light bulbs having a power output of
1 mW/cm.sup.2. Clear 1.4 mm thick elastomeric specimens were
obtained.
6 TABLE 6 Example 1 Example 2 Example 3 Example 4 TAIC 5.0 g -- 5.0
g -- TAC -- 5.0 g -- 5.0 g DMDS 4.6 g 4.6 g -- -- HDT -- -- 4.5 g
4.5 g IGRACURE 651 0.048 g 0.048 g 0.048 g 0.048 g
Comparative Examples 1-5
[0058] Comparative Examples 1-5 were prepared by mixing the
components in the ratios identified in Table 7. The resins were
cured by placing 6 grams of the liquid mixture into a 70 mm
diameter aluminum dish, heating to 50.degree. C., and irradiating
for 1 hour under two Sylvania 350 nm black light bulbs having a
power output of 1 mW/cm.sup.2. Clear 1.4 mm thick elastomeric
specimens were obtained.
7 TABLE 7 Comparative Comparative Comparative Comparative
Comparative Example 1 Example 2 Example 3 Example 4 Example 5 TAIC
5.0 g 5.0 g 5.0 g -- -- TAC -- -- -- 5.0 g 5.0 g DMDO 5.46 g -- --
5.46 g -- EBMP -- 7.14 g -- -- 7.14 g CAPCURE .RTM. -- -- 16.2 g --
-- 3-800 IRGACURE 0.053 g 0.061 g -- 0.053 g 0.061 g 651
[0059] Absorption Performance at 60.degree. C.
[0060] The swelling volume of the cured Examples 1-4 and
Comparative Examples 1-5 were measured. Specimens weighing
approximately 0.5 grams were cut from the 1.4 mm thick films
prepared above, dried for 1 hour in a vacuum oven at a temperature
of 100.degree. C. and pressure of 2 torr (266 Pa) and carefully
weighed before immersion in distilled water and in a 96/4 mixture,
by weight, of water/n-butyl alcohol at 60.degree. C. The samples
were removed from the liquids carefully patted dry with a paper
towel, and weighed after 24 and 72 hours. The percent weight gain
was calculated by the following formula: (swollen weight)-(original
weight)/(original weight). The results of this experiment are
reported in Table 8.
8 TABLE 8 % Weight Gain % Weight Gain in Water/n - butanol in
Water/n - butanol % Weight Gain % Weight Gain 96/4 96/4 in Water
(24 hr) in Water (72 hr) (24 hr) (72 hr) Example 1 1.0% 1.0% 1.2%
1.4% Example 2 0.8% 0.8% 2.42% 3.19% Example 3 0.6% 0.6% 2.1% 2.7%
Example 4 0.6% 0.6% 3.42% 4.12% Comparative 2.1% 2.1% 6.4% 6.3%
Example 1 Comparative 2.9% 3.6% 6.2% 7.3% Example 2 Comparative
8.5% 8.0% 22.4% 18.76% Example 3 Comparative 1.8% 1.8% 7.7% 7.8%
Example 4 Comparative 2.0% 2.4% 8.0% 7.8% Example 5
[0061] The data in Table 8 clearly show that the ene-thiol resins
of Examples 1-4 are much more resistant to swelling in water and in
water/n-butanol than Comparative Examples 1-5. The water/butanol
mixture was used to simulate the swelling characteristics of
corrosive inks. The presence of a nonaqueous component such as
butanol significantly increases the swelling of the elastomer
network as compared to swelling obtained using water alone. Many
available inks have significant amounts of water miscible solvents
which typically increase swelling of and, in general, facilitates
degradation of the elastomer network.
[0062] The absorption data in Table 8 also clearly demonstrates the
importance of maximizing thioether content and minimizing
hydrophilic units in the network. The performance of Examples 1 and
2 when compared to that of Comparative Examples 1 and 4 is
particularly surprising. The dimercaptans, DMDO and DMDS, are
structurally very similar and the physical properties of the cured
networks before exposure to water were very similar. However, the
resistance to water and water/n-butanol swell of DMDO and DMDS
networks is very different.
[0063] Absorption Performance at 22.degree. C.
[0064] The swelling of Examples 1-4 and Comparative Examples 1-4,
was also measured in a 96/4 mixture of water/n-butanol at room
temperature (22.degree. C.) and in Lexmark inks. The cyan ink is
from Lexmark's colored ink jet cartridge, part number 12A1980. The
composite ink is a mixture of cyan, magenta, and yellow inks from
Lexmark's colored ink jet cartridge, part number 12A1980. The black
ink is from Lexmark's black ink jet cartridge part number 12A1970.
Specimens weighing approximately 0.2 gram were cut from the 1.4 mm
thick films prepared above, dried for 24 hours at 60.degree. C. in
a vacuum oven, and weighed before immersion in the ink or
water/n-butanol solution. The samples swelled in the
water/n-butanol mixture or water were immersed at room temperature
and removed periodically, carefully dried with a paper towel, and
weighed. The samples swelled in the inks were immersed in ink and
stored at 60.degree. C. They were periodically removed, and the
samples were rinsed with water to remove the ink. They were patted
dry with a paper towel and carefully weighed. This is the standard
swelling procedure used in all examples and comparative examples.
The percentage weight gain was calculated from the formula:
(swollen weight)-(original weight)/(original weight). Samples
soaked in water/n-butanol or water were soaked for a total of 15
days. After 15 days, the samples were dried in a vacuum oven at
60.degree. C. for 48 to 96 hours to remove the water and n-butanol
from the samples. This dried down weight was recorded and used to
report a corrected weight gain for the 15 day swelling studies. The
corrected percentage weight gain for the 15 day swelling studies
was calculated from the following formula: (swollen weight)-(dried
down weight)/(dried down weight). This number is reported to
correct for any weight losses in the samples due to extraction by
the water or water/n-butanol mixture of any uncured material.
[0065] The data in Table 9 show the percentage weight increase in
water/n-butanol and ink for the examples and comparative examples.
The data in Table 9 clearly indicate that Examples 1-4, containing
no oxygen ether or ester linkages in the dimercaptan backbone, are
much more resistant to swelling in water/n-butanol and ink than the
comparative examples, which contain ether or ester linkages in the
backbone. Dramatic weight losses over several days in ink were
observed for Comparative Examples 2 and 5, which contain easily
hydrolyzed ester functional groups.
9 TABLE 9 % Weight Gain in Water/n-butanol 96/4 (7 day/15 day
Composite (5 Cyan (5 day/20 Black (5 day/20 corrected.sup.a) day/20
day day day Example 1 0.46%/0.60% 1.26%/2.01% 1.23%/1.57%
1.22%/1.34% Example 2 0.71%/0.99% 1.80%/2.07% 1.77%/1.96%
1.04%/1.30% Example 3 0.64%/0.74% 1.52%/2.31% 1.50%/2.10%
1.04%/1.04% Example 4 1.00%/1.35% 2.25%/2.38% 1.93%/1.93%
1.00%/1.00% Comparative 3.76%/4.20% 4.65%/5.05% 5.06%/6.35%
3.56%/3.55% Example 1 Comparative 5.51%/6.61% 7.33%/1.17%
9.86%/10.32% .sup. 7.98%/5.88%.sup.b Example 2 Comparative
4.46%/4.86% 4.94%/5.11% 5.39%/5.29% 3.38%/3.14% Example 4
Comparative 3.63%/4.41% 6.97%/9.61% 6.87%/9.19% 4.93%/0.69% Example
5 .sup.aThe samples were dried for 96 hours to obtain the corrected
weight. .sup.bThese numbers represent 2 and 5 day data because the
sample had disintegrated by 20 days.
Example 5
[0066] Samples 1-20 are examples of the invention. These samples
exemplify that ene-thiol oligomers containing small amounts of
oxygen ether linkages and large amounts of thioether linkages can
be crosslinked to form solvent, water, and ink resistant
elastomeric networks. The samples were prepared by mixing oligomers
with either TAIC or TAC as described in the table below. The
samples were mixed with 0.5 percent IRGACURE 651 and poured into an
aluminum dish or poured into a mold made from two glass plates
covered with release liner separated by a {fraction (1/16)} inch
silicone spacer. The samples were irradiated for 1 hour with two
GTE 15 watt Sylvania 350 nm black light bulbs having a power output
of 1 mW/cm.sup.2. The preparation of the samples is described in
Table 10.
10 TABLE 10 Oligomer Crosslinker Oligomer Weight Crosslinker Weight
Sample 1 Oligomer 1 19.22 g TAC 0.97 g Sample 2 Oligomer 1 17.52 g
TAIC 0.89 g Sample 3 Oligomer 2 5.21 g TAC 1.00 g Sample 4 Oligomer
2 12.18 g TAIC 2.33 g Sample 5 Oligomer 3 16.30 g TAC 0.99 g Sample
6 Oligomer 3 15.04 g TAIC 0.94 g Sample 7 Oligomer 4 5.03 g TAC
1.08 g Sample 8 Oligomer 4 5.03 g TAIC 1.09 g Sample 9 Oligomer 5
16.53 g TAC 0.88 g Sample 10 Oligomer 5 13.92 g TAIC 0.74 g Sample
11 Oligomer 6 5.15 g TAC 1.03 g Sample 12 Oligomer 6 13.09 g TAIC
2.61 g Sample 13 Oligomer 7 15.88 g TAC 0.98 g Sample 14 Oligomer 8
10.17 g TAC 1.51 g Sample 15 Oligomer 9 15.97 g TAC 0.91 g Sample
16 Oligomer 10 5.11 g TAC 0.98 g Sample 17 Oligomer 10 5.51 g TAIC
1.05 g Sample 18 Oligomer 11 16.13 g TAC 0.87 g Sample 19 Oligomer
12 4.11 g TAC 0.82 g Sample 20 Oligomer 12 4.07 g TAIC 0.81 g
[0067] The ink and moisture resistance for Samples 1-20 is shown in
Table 12. The {fraction (1/16)} inch samples were cut into pieces
weighing approximately 0.2 gram, and the standard swelling
procedure described above was used. Samples 1-20 swelled less than
4 percent in 96/4 water/n-butanol at room temperature in 15 days.
Additionally, most of these samples did not pick up more than 2
percent weight after being immersed in water at 60.degree. C. for
15 days. Also remarkable is that each of these materials swelled
less than 4 percent at 60.degree. C. in each of the inks that were
tested. These elastomers have low crosslink densities, either 1000
or 3000 molecular weight between crosslinks. This example
demonstrates that lightly crosslinked materials in which the number
of thioether groups is maximized and the amount of oxygen ether
groups is minimized are resistant to swelling by ink, water, and
solvent.
Example 6
[0068] Sample 21 was prepared to exemplify that a dimercaptan
monomer containing four sulfurs in the backbone can be used to
prepare ink resistant elastomeric networks. It was prepared by
mixing DMDT (2.03 grams), TAIC (1.57 grams), and IRGACURE 819
(0.018 gram) in an aluminum dish on a hot plate. It was passed
through a Fusion processor 10 times at 20 ft./min. using the Fusion
V Bulb.
[0069] Sample 21 was tested in water and water/n-butanol using the
standard swelling procedure. The water/n-butanol and water
resistance of Sample 21 is shown in Table 12 and is very similar
the data obtained for Example 1 which contains DMDS in its
backbone. The equilibrium water/n-butanol uptake at room
temperature is approximately 0.5 percent, and the equilibrium water
uptake at 60.degree. C. is approximately 1 percent. Therefore,
DMDT, which contains no oxygen ether or ester linkages, is a
dimercaptan monomer that can be used to make resins that are
resistant to swelling in ink, water, or solvent.
Example 7
[0070] Samples 22 and 23 are described in Table 11 and exemplify
another method for synthesizing ink resistant elastomers using
ene-thiol chemistry. In these samples, a small amount of
difunctional olefin monomer, CHVE, was added to a difunctional
mercaptan and TAIC. These three monomers form a low viscosity
solution. The molecular weight between crosslinks can be adjusted
by the ratio of CHVE and TAIC. For these samples, a dimercaptan
monomer, CHVE, TAIC, 500 ppm NPAL, and 0.5 percent IRGACURE 651
were combined and stirred thoroughly. The NPAL was added to prevent
premature gelling of the resin. The liquid was poured into a mold
made from two glass plates covered with release liners and a
{fraction (1/16)} inch silicone spacer. The samples were irradiated
for 1 hour with two GTE 15 watt Sylvania 350 nm black light bulbs
having a power output of 1 mW/cm.sup.2.
11 TABLE 11 DMDS DMDT CHVE TAIC Sample 22 8.04 g -- 3.45 g 5.74 g
Sample 23 -- 9.18 g 2.84 g 4.70 g
[0071] Samples 22 and 23 were tested in water/n-butanol and water
using the standard swelling procedure. The swelling of Samples 22
and 23 in water/n-butanol and water is reported in Table 12 and is
also quite low. The equilibrium water/n-butanol uptake is less than
1.5 percent for both samples, and the equilibrium moisture uptake
is approximately 1 percent. Thus, solvent and moisture resistant
resins can be prepared by mixing a dimercaptan with a mixture of
difunctional and trifunctional olefins and photochemically curing
the resulting solution.
[0072] Absorption Performance
[0073] Table 12 contains the absorption performance data. The
swelling procedures described above were used. The percentage
weight gain in ink was calculated from the formula: (swollen
weight)-(original weight)/(original weight). The corrected
percentage weight gain in water/n-butanol or water was calculated
from the following formula: (swollen weight)-(dried down
weight)/(dried down weight). To obtain the dried down weight,
Samples 1-20 were dried for 48 hours, and Samples 21-23 were dried
for 96 hours.
12 TABLE 12 Water/n-butanol 96/4 Water (7 (7 day/15 day day/15 day
Composite (7 Cyan (7 Black (2 day/7 corrected) corrected) day/15
day) day/15 day) day) Sample 1 2.30%/2.08% 0.90%/1.31% 2.52%/2.45%
2.45%/2.38% 0.89%/0.71% Sample 2 2.29%/2.07% 0.89%/1.10%
2.26%/2.31% 2.41%/2.58% 0.73%/0.58% Sample 3 2.01%/2.35%
0.63%/1.09% 2.43%/2.17% 2.22%/2.53% 0.39%/-.13% Sample 4
1.65%/2.26% 0.42%/1.06% 2.10%/2.10% 2.28%/2.55% 0.54%/0.54% Sample
5 1.15%/1.87% 0.85%/1.37% 2.81%/2.87% 2.47%/2.41% 0.45%/0.57%
Sample 6 1.51%/1.93% 0.80%/1.43% 2.62%/2.70% 2.50%/2.43%
0.60%/0.40% Sample 7 1.28%/1.73% 0.82%/1.28% 2.27%/2.40%
2.45%/2.67% 0.60%/0.12% Sample 8 0.99%/1.37% 0.79%/1.13%
2.26%/2.42% 2.36%/2.52% 0.51%/0.00% Sample 9 0.88%/1.17%
1.20%/2.80% 1.97%/1.97% 2.29%/2.40% 0.30% Sample 10 0.71%/1.18%
0.52%/0.59% 1.54%/1.39% 1.62%/1.68% 0.42% Sample 11 0.58%/0.95%
0.30%/0.73% 1.16%/1.10% 1.55%/1.69% 0.48%/0.20% Sample 12
0.34%/0.43% 0.14%/0.48% 1.13%/0.92% 1.47%/1.55% 0.43%/0.43% Sample
13 0.57%/0.91% 0.17%/1.38% 0.84%/1.25% 0.85%/0.92% -0.24%/-0.30%
Sample 14 0.45%/0.68% 0.11%/1.05% 1.09%/1.03% 0.94%/1.00%
0.32%/0.00% Sample 15 0.76%/1.40% 1.21%/2.94% 1.99%/1.81%
2.20%/2.08% 0.28%/0.14% Sample 16 1.28%/2.14% 0.43%/0.86%
1.27%/1.27% 1.53%/1.70% 0.42%/0.50% Sample 17 0.99%/1.28%
0.41%/0.99% 1.43%/1.24% 1.83%/1.90% 0.54%/0.67% Sample 18
3.70%/3.77% 0.86%/1.19% 3.56%/3.25% 3.29%/3.45% 0.71%/0.65% Sample
19 3.52%/3.84% 0.60%/1.04% 3.14%/3.45% 3.48%/3.48% 1.08%/0.67%
Sample 20 3.29%/3.60% 1.03%/1.41% 3.07%/3.36% 3.35%/3.46%
0.91%/0.45% Sample 21 0.49%/0.55% 1.01%/1.24% Sample 22 0.91%/1.18%
0.85%/1.11% Sample 23 1.20%/1.45% 0.76%/0.84%
Comparative Example 6
[0074] This comparative example demonstrates that ene-thiol
networks containing significant amounts of oxygen ether linkages
have poorer resistance to ink, solvent, and water than Samples
1-20. Comparative Samples CS 1-CS 10 were made by reaction of
Oligomers 13-18 with either TAIC or TAC as shown in Table 13. The
sample preparation procedure was described in Example 6. The
solvent, water, and ink resistance of the comparative samples are
shown in Table 11. For each of these samples, the swelling in
water/n-butanol and inks is higher than that shown in Table 13. The
swelling of samples containing large amounts of oxygen ether
linkages is as high as 20 percent in water/n-butanol and 17 percent
in ink.
13 TABLE 13 Oligomer Crosslinker Oligomer Weight Crosslinker Weight
CS 1 Oligomer 13 11.19 g TAC 0.60 g CS 2 Oligomer 14 4.10 g TAC
0.77 g CS 3 Oligomer 14 12.28 g TAIC 2.30 g CS 4 Oligomer 15 14.93
g TAC 0.92 g CS 5 Oligomer 16 4.06 g TAC 0.80 g CS 6 Oligomer 16
4.29 g TAIC 0.87 g CS 7 Oligomer 17 17.38 g TAC 1.07 g CS 8
Oligomer 17 14.44 g TAIC 0.90 g CS 9 Oligomer 18 4.05 g TAC 0.76 g
CS 10 Oligomer 18 4.22 g TAIC 0.81 g
[0075] Comparative Sample CS 11 demonstrates that an elastomer made
from a DMDO, a difunctional olefin, and a trifunctional olefin has
poorer solvent and moisture resistance than samples made from
dimercaptans containing no oxygen ether linkages. Comparative
Sample CS 11 was prepared as described for Samples 22 and 23. DMDO
(9.03 grams), CHVE (3.28 grams), and TAIC (5.46 grams) were stirred
together 500 ppm NPAL and 0.5 percent IRGACURE 651. The liquid was
poured into a {fraction (1/16)} inch glass mold and cured. The
water/n-butanol and water uptake for this comparative sample, shown
in Table 14, is much higher than was found for Samples 22 and 23,
which were made from DMDS and DMDT.
[0076] Comparative Absorption Data
[0077] For the comparative absorption performance data, shown in
Table 14, the standard swelling procedure was used. The percentage
weight gain for the inks was calculated from the formula: (swollen
weight)-(original weight)/(original weight). The corrected
percentage weight gain in water/n-butanol or water was calculated
from the following formula: (swollen weight)-(dried down
weight)/(dried down weight). To obtain the dried down weight,
Comparative Samples CS 1-CS 10 were dried for 48 hours, and
Comparative Sample CS 11 was dried for 96 hours.
14TABLE 14 Water/n-butanol Water (7 96/4 (7 day/15 day/15 day
Composite (7 Cyan (7 day/15 Black (2 day corrected) corrected)
day/15 day) day) day/7 day) CS 1 6.12%/6.25% 1.33%/1.80%
5.40%/5.29% 5.58%/5.37% 1.06%/0.57% CS 2 5.22%/5.22% 1.47%/1.96%
4.79%/4.85% 5.31%/5.47% 1.61%/1.54% CS 3 5.05%/5.39% 1.40%/1.88%
5.02%/5.02% 5.52%/5.59% 1.98%/1.67% CS 4 11.70%/12.68% 3.75%/5.00%
10.43%/10.71% 10.76%/10.70% 5.10%/5.31% CS 5 6.83%/6.04%
2.82%/3.60% 6.17%/6.17% 7.37%/7.14% 2.94%/2.76% CS 6 7.12%/7.68%
3.04%/4.20% 6.70%/6.59% 7.37%/7.62% 3.56%/3.56% CS 7 18.02%/18.58%
5.83%/7.10% 15.55%/15.49% 16.24%/16.02% 9.34%/9.09% CS 8
17.98%/19.62% 5.50%/7.13% 15.67%/15.33% 16.30%/16.30% 9.37%/9.37%
CS 9 10.56%/11.46% 3.91%/5.11% 10.10%/9.97% 10.88%/11.87%
6.69%/5.47% CS 10 11.08%/11.37% 4.07%/5.26% 10.84%/10.84%
11.03%/11.84% 5.76%/5.26% CS 11 4.68%/5.15% 1.94%/2.22%
Example 8
[0078] Example 8 is a comparison of selected samples having
different amounts of sulfur and oxygen present in the network.
Example 8 features the water/n-butanol, water, and cyan ink
swelling of selected samples prepared from oligomers having a
theoretical molecular weight of 2800. The molecular weight between
crosslinks for these samples is approximately 3000. The swelling
data for the selected samples is summarized in Table 15. Also
included in Table 15 is the sulfur weight percent and oxygen weight
percent in the oligomer that was used to prepare in the selected
samples. This example demonstrates that as the weight percent of
sulfur in the oligomer backbone increases and the weight percent of
oxygen in the oligomer decreases, the swelling performance of the
network improves.
15 TABLE 15 96/4 water/n-butanol swell Water swell (7 day/15 day (7
day/15 day Cyan swell S weight % O weight % corrected) corrected (7
day/15 day) CS 1 18 17 6.12%/6.25% 1.33%/1.80% 5.58%/5.37% Sample
18 26 11 3.70%/3.77% 0.86%/1.19% 3.29%/3.45% Sample 1 29 8.7
2.30%/2.08% 0.90%/1.31% 2.45%/2.38% Sample 15 33 5 0.76%/1.40%
1.21%/2.94% 2.20%/2.08% Sample 9 38 0.88%/1.17% 1.20%/2.80%
2.29%/2.40%
Example 9
[0079] Example 9 is a comparison of selected samples having
different amounts of sulfur and oxygen present in the network.
Example 9 features the water/n-butanol, water, and cyan ink
swelling of selected samples prepared from oligomers having a
theoretical molecular weight of 830. The molecular weight between
crosslinks for these samples is approximately 1000. The swelling
data for the selected samples is summarized in Table 16. Also
included in Table 16 is the sulfur weight percent and oxygen weight
percent in the oligomer that was used to prepare in the selected
samples. This example demonstrates that as the weight percent of
sulfur in the oligomer backbone increases and the weight percent of
oxygen in the oligomer decreases, the swelling performance of the
network improves.
16 TABLE 16 96/4 water/butanol Water Cyan S Weight % O Weight % (3
day/7 day) (3 day/7 day) (2 day/7 day) CS 2 21 17 5.22%/5.22%
1.47%/1.96% 5.31%/5.47% Sample 19 28 13 3.52%/3.84% 0.60%/1.04%
3.48%/3.48% Sample 3 33 7.4 2.01%/2.35% 0.63%/1.09% 2.22%/2.53%
Sample 16 36 4.2 1.28%/2.14% 0.43%/0.86% 1.53%/1.70% Sample 11 41
0.58%/0.95% 0.30%/0.73% 1.55%/1.69%
Example 10
[0080] Example 10 demonstrates the low moisture permeability of
thioether containing networks when compared to similar networks
containing oxygen ether linkages. In each sample, a difunctional
mercaptan was mixed with either TAIC or TAC, 0.5 percent
photoinitiator, and in some cases 500 ppm NPAL. The samples were
mixed thoroughly at approximately 50.degree. C. and then degassed
in a vacuum oven. Each sample was sandwiched between two glass
plates that had been coated with Teflon tape. The plates were
separated by spacers that were approximately 4 mils thick. The
samples were then passed through a Fusion processor at 25 ft/min,
five times on each side. Samples containing IRGACURE 651 as the
photoinitiator were cured with the Fusion D bulb, and samples
containing IRGACURE 819 as the photoinitiator were cured with the
Fusion V bulb. Samples 24-32 were prepared in this way and are
presented in Table 17.
[0081] The permeability test was based on ASTM D814. A "standard"
circular die 75 mm in diameter was used to punch press specimens
from film samples ranging from 80 to 150 microns thick. Release
liners were used on both sides of the specimen to make it easier to
handle and measure. This "sandwich" was measured in 10 locations,
and the average net film thickness was recorded.
[0082] The specimens were carefully removed from the liners and
placed onto fluoroelastomeric gaskets with an outside diameter
(O.D.) of 75 mm, an inside diameter (I.D.) of 63.5 mm, and a
thickness of 1.5 mm. The gasket and specimen were then placed onto
the flanged rim of an aluminum permeation cup containing 100 mL of
deionized water. The cup has a volume of 250 mL. A second gasket, 3
mm thick, was placed over the first gasket and the specimen, and a
75 mm diameter piece of window screen was then placed on top of all
three. This screen served to prevent stretching of extensible
materials.
[0083] The gaskets, specimen, and screen were held in place by a
circular aluminum ring with an I.D. of 63.5 mm and an O.D. of 88
mm. Along the outer edge of this ring were six evenly distributed
threaded holes, through which screws pass into the flanged rim of
the cup. The screws were loosely put in place and the entire
assembly placed into a 40.degree. C. oven. After allowing the
assembly to equilibrate for 1 hour, the screws were securely
tightened, the cup was removed from the oven, and the initial
weight was taken. Weights were taken every day or so for the first
week, about every third day the second week, and about every fifth
day thereafter.
[0084] The permeability (g-mm/m.sup.2-day@40.degree. C.), or
moisture vapor transmission rate, was calculated by multiplying the
film thickness (mm) by the total water weight loss (gram), and
dividing by the area of the film (0.003167 m.sup.2) and the number
hours divided by 24 (day). The permeabilities of Samples 24-32 are
shown in Table 17.
17 TABLE 17 TAIC Dimercaptan Weight (g) TAC (g) Initiator NPAL
Permeability Sample 24 DMDS 5.54 g 5.96 g -- 819 Yes 9 Sample 25
DMDS 14.07 g -- 15.16 g 651 Yes 17 Sample 26 Oligomer 1 8.48 g 0.43
g -- 651 No 48 Sample 27 Oligomer 2 12.18 g 2.33 g -- 651 No 35
Sample 28 Oligomer 4 7.96 g -- 1.71 g 651 No 29 Sample 29 Oligomer
4 6.86 g 1.49 g -- 651 No 24 Sample 30 Oligomer 6 13.09 g 2.61 g --
651 No 18 Sample 31 Oligomer 9 7.25 g 0.42 g -- 651 No 35 Sample 32
Oligomer 10 5.09 g 0.98 g -- 651 No 24
Comparative Example 7
[0085] This comparative example demonstrates the higher moisture
permeability of samples containing significant amounts of oxygen
ether linkages when compared to Samples 24-32. Comparative Samples
CS 12-CS 15 were prepared and measured as described in Example 10
and are summarized in Table 18.
18 TABLE 18 Dimercaptan Weight TAIC TAC NPAL Initiator Permeability
CS 12 DMDO 5.11 g 4.67 g -- yes 651 55 CS 13 DMDO 5.36 g -- 4.88 g
yes 819 52 CS 14 EBMP 6.63 g 4.61 g -- yes 651 59 CS 15 Oligomer 14
12.28 g 2.30 g -- no 651 99
Example 11
[0086] Example 11 is a comparison of samples containing different
weight percentages of sulfur and oxygen in the network but
containing the same molecular weight between crosslinks. Each
sample was prepared from an oligomer with a theoretical molecular
weight of 830 and TAIC as the crosslinker. For each sample, the
molecular weight between crosslinks is approximately 1000. This is
important because the crosslink density of the sample greatly
affects the permeability of the sample. The weight percentages of
sulfur and oxygen in the oligomers used to prepare the samples as
well as the moisture permeability are reported in Table 19. The
data in Table 19 indicate that the permeability of samples
containing the same crosslink density varies significantly with the
weight percentages of sulfur and oxygen in the backbone. As the
weight percentage of sulfur increase and the weight percentage of
oxygen decreases, the permeability of the sample decreases. This
example demonstrates that the moisture permeability of ene-thiol
networks can be lowered by maximizing the amount of thioether
linkages and minimizing the amount of oxygen ether linkages in the
backbone.
19 TABLE 19 S Weight % O Weight % Permeability CS 15 21 17 99
Sample 27 33 7.4 35 Sample 32 36 4.2 24 Sample 30 41 0 18
Example 12
[0087] Example 12 demonstrates that the odor of thioether oligomers
can be decreased by the removal of volatile components. An oligomer
of DMDS and CHVE having a molecular weight of 1700 was prepared by
the thermal procedure. This oligomer (320 grams) was heated to
80.degree. C. and was dropped into a UIC rolled film evaporator.
The jacket temperature of the column was 100.degree. C., and
apparatus was under a vacuum of 0.009 mm Hg. Two cold traps, a cold
finger with a temperature of 20.degree. C., and a liquid nitrogen
trap to protect the vacuum pump, were used. The rollers were set at
a speed of 300 rpm. Following this treatment of the oligomer, 2.0
gram of material were collected in the cold finger, and 3.3 grams
of material were collected in the liquid nitrogen trap. The
material stripped from the oligomer was analyzed and found to
contain mostly residual monomer and cyclic impurities from the
monomer. The odor of the oligomer was significantly reduced. A
second treatment of 225 grams of the oligomer was carried out with
a column temperature of 150.degree. C. An additional 0.22 grams of
material was collected, and the odor of the oligomer was reduced
further.
[0088] Other embodiments are within the following claims. While the
invention has been described with reference to the particular
embodiments and drawings set forth above, the spirit of the
invention is not so limited and is defined by the appended
claims.
* * * * *