U.S. patent application number 11/171800 was filed with the patent office on 2005-10-27 for functional fluorescent dyes.
This patent application is currently assigned to 3M innovative Properties Company. Invention is credited to Olson, David B..
Application Number | 20050240020 11/171800 |
Document ID | / |
Family ID | 30770259 |
Filed Date | 2005-10-27 |
United States Patent
Application |
20050240020 |
Kind Code |
A1 |
Olson, David B. |
October 27, 2005 |
Functional fluorescent dyes
Abstract
Fluorescent functional dyes represented by the following
formulas: 1 wherein R.sub.1 is hydrogen or methyl; R.sub.2,
R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are each independently
selected from the group consisting of hydrogen, alkyl, aryl,
alkoxy, aralkyl, alkaryl, halo, and trifluoromethyl; and L is a
straight chain or branched chain alkylene containing 3 to about 15
carbon atoms, the alkylene group optionally containing one or more
catenary heteroatoms.
Inventors: |
Olson, David B.; (Marine on
Saint Croix, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M innovative Properties
Company
|
Family ID: |
30770259 |
Appl. No.: |
11/171800 |
Filed: |
June 30, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11171800 |
Jun 30, 2005 |
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10206315 |
Jul 26, 2002 |
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6930184 |
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Current U.S.
Class: |
546/47 |
Current CPC
Class: |
H05K 1/0269 20130101;
H05K 2203/161 20130101; C09B 23/02 20130101; C09B 57/14 20130101;
H05K 3/285 20130101 |
Class at
Publication: |
546/047 |
International
Class: |
C07D 471/00 |
Claims
What is claimed:
1. A compound represented by the following formula: 23wherein
R.sub.1 is hydrogen or methyl; R.sub.5 and R.sub.6 are each
independently selected from the group consisting of hydrogen,
alkyl, aryl, alkoxy, aralkyl, alkaryl, halo, and trifluoromethyl;
and L is a divalent alkylene containing 1 to about 15 carbon atoms,
the alkylene group optionally containing one or more catenary
heteroatoms.
2. The compound of claim 1 represented by the following formula:
24wherein n is an integer from 1 to about 15; R1 is hydrogen or
methyl; and R5 and R6 are independently selected from the group
consisting of hydrogen, alkyl, aryl, alkoxy, aralkyl, alkaryl,
halo, and trifluoromethyl.
3. The compound of claim 2 wherein n is 7.
4. An oligomer or copolymer comprising a compound represented by
the following general formula: 25wherein R.sub.1 is hydrogen or
methyl; R.sub.2, R.sub.3, and R.sub.4 are each independently
selected from the group consisting of hydrogen, alkyl, aryl,
alkoxy, aralkyl, alkaryl, halo, and trifluoromethyl; and L is a
divalent alkylene containing 3 to about 15 carbon atoms, the
alkylene group optionally containing one or more catenary
heteroatoms.
5. The oligomer or copolymer of claim 4 wherein said oligomer or
copolymer comprises the polymerization product of one or more
fluoromonomers.
6. A coating composition comprising a compound represented by the
following general formula: 26wherein R.sub.1 is hydrogen or methyl;
R.sub.2, R.sub.3, and R.sub.4 are each independently selected from
the group consisting of hydrogen, alkyl, aryl, alkoxy, aralkyl,
alkaryl, halo, and trifluoromethyl; and L is a divalent alkylene
containing 3 to about 15 carbon atoms, the alkylene group
optionally containing one or more catenary heteroatoms.
7. A film comprising the cured coating composition of claim 6.
8. An oligomer or copolymer comprising the compound of claim 1.
9. The oligomer or copolymer of claim 8 wherein said oligomer or
copolymer comprises the polymerization product of one or more
fluoromonomers.
10. A coating composition comprising the compound of claim 1.
11. A film comprising the coating composition of claim 10.
12. A circuit board comprising the coating composition of claim
6.
13. A circuit board comprising the film of claim 7.
14. A circuit board comprising the coating composition of claim
10.
15. A circuit board comprising the film of claim 11.
Description
[0001] This application is a divisional of U.S. Ser. No.
10/206,315, filed Jul. 26, 2002, now allowed, the disclosure of
which is herein incorporated by reference.
FIELD
[0002] This invention relates to fluorescent dyes and, in other
aspects, to polymer coatings and films comprising the dyes.
BACKGROUND
[0003] Conformal coatings are protective coatings that conform to
the surface of electronic components and circuit board assemblies.
Properly applied conformal coatings can increase the working life
of the assemblies by protecting its components and the board
itself. Proper coverage and uniformity of the conformal coating
over the assembly is critical for effective protection of the
assembly. It can be difficult, however, to determine the integrity
and uniformity of the conformal coating when it is coated on an
assembly. Therefore, the conformal coating material is sometimes
doped with a fluorescent dye or "tracer" to aid in the quality
assurance inspection of the assembly for proper coverage.
[0004] Fluorescent dyes such as, for example, thioxanthene
compounds, work well for imparting color to certain plastic
materials such as, for example, polymethacrylate, polycarbonate,
polystyrene, and polyester. Most fluorescent dyes, however, have
poor or limited solubility in certain polymer matrixes. For
instance, most fluorescent dyes have poor or no compatibility with
fluorochemical monomers and polymers. This results in poor color
quality and dye bleed and little or no color entrainment into the
resulting fluoropolymer. Fluoropolymers containing dyes are
therefore typically not used when leaching and toxicity issues are
of concern (for example, in food packaging and medical
applications). There is also little advantage in adding most dyes
to fluoropolymer conformal coatings since the dyes typically do not
entrain uniformly throughout the coating such that they are useful
during quality control inspection.
SUMMARY
[0005] In view of the foregoing, we recognize that there is a need
for fluorescent dyes that are compatible with various polymer
matrixes, including fluoropolymers, and that impart stable color to
resulting polymers and fluoropolymers.
[0006] Briefly, in one aspect, the present invention provides novel
fluorescent acrylate functional dyes represented by the following
formula (hereinafter referred to as "yellow-green fluorescent
dyes"): 2
[0007] wherein R.sub.1 is hydrogen or methyl; R.sub.2, R.sub.3, and
R.sub.4 are each independently selected from the group consisting
of hydrogen, alkyl, aryl, alkoxy, aralkyl, alkaryl, halo, and
trifluoromethyl; and L is a divalent alkylene (straight chain or
branched chain) containing 3 to about 15 carbon atoms, the alkylene
group optionally containing one or more catenary heteroatoms. As
used herein, the term "catenary heteroatoms" means a heteroatom
(for example, nitrogen, oxygen, or sulfur) that replaces one or
more carbon atoms of the L linking group in a manner such that the
heteroatom is bonded to at least two carbon atoms of the L linking
group.
[0008] A preferred embodiment of the yellow-green fluorescent dyes
of the invention can be represented by the following formula: 3
[0009] wherein n is an integer from 2 to about 15; R.sub.1 is
hydrogen or methyl; and R.sub.2, R.sub.3, and R.sub.4 are each
independently selected from the group consisting of hydrogen,
alkyl, aryl, alkoxy, aralkyl, alkaryl, halo, and trifluoromethyl.
Preferably, n is 4 or 5; more preferably, n is 4.
[0010] In another aspect, this invention provides novel fluorescent
acrylate functional dyes represented by the following formula
(hereinafter referred to as "red fluorescent dyes": 4
[0011] wherein R.sub.1 is hydrogen or methyl; R.sub.5 and R.sub.6
are each independently selected from the group consisting of
hydrogen, alkyl, aryl, alkoxy, aralkyl, alkaryl, halo, and
trifluoromethyl; and L is a divalent alkylene (straight chain or
branched chain) containing 1 to about 15 carbon atoms, the alkylene
group optionally containing one or more catenary heteroatoms.
[0012] A preferred embodiment of red fluorescent dyes of the
invention can be represented by the following formula: 5
[0013] wherein n is an integer from 1 to about 15; R1 is hydrogen
or methyl; and R5 and R6 are independently selected from the group
consisting of hydrogen, alkyl, aryl, alkoxy, aralkyl, alkaryl,
halo, and trifluoromethyl. Preferably, n is 7.
[0014] It has been discovered that the above-described yellow-green
and red fluorescent dyes can be covalently bonded to oligomers and
polymers and are therefore surprisingly compatible with various
polymer systems, including fluoropolymer systems. The yellow-green
and red fluorescent dyes of the invention can, for example, be
co-polymerized with fluorochemical acrylate monomers to give
fluorescent dyed fluoropolymers that are highly resistant to
leaching and blooming. Such fluorescent dyed fluoropolymers are
useful, for example, as conformal coatings and in many medical and
food packaging applications where leaching and toxicity issues are
of concern.
[0015] Thus, the compounds of the invention meet the need in the
art for fluorescent dyes that have increased solubility in and are
compatible with various polymers and fluoropolymers. The dyes of
the invention are useful for imparting color and fluorescence to
various articles (for example, food packaging and medical articles
such as respiratory masks) and in particular to fluoropolymer
conformal coatings used to protect electronic components.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0016] As referred to herein, the term "dye" shall mean substances
which impart color to a substrate by selective absorption of
wavelengths of light.
[0017] As referred to herein the term "chromogen" shall refer to
the aromatic portion of the dye.
[0018] As referred to herein, the term "chromophore" shall refer to
the specific groupings of substituents on the chromogen which give
rise to various colors selectively shifting the absorption of the
wavelength of light.
[0019] The term "alkyl" refers to straight or branched hydrocarbon
radicals, such as, for example, methyl, ethyl, propyl, butyl,
octyl, isopropyl, tert-butyl, sec-pentyl, and the like. Alkyl
groups can either be unsubstituted or substituted with one or more
substituents (for example, halogen, alkoxy, aryl, arylalkyl,
aralkoxy, and the like).
[0020] The term "alkenyl" refers to straight or branched
unsaturated hydrocarbon radicals having one or more double bonds
such as, for example, ethylene, propylene, butylene,
1,3-pentadiene, 1,4-pentadiene, and the like. Alkenyl groups can
either be unsubstituted or substituted with one or more
substituents (for example, haloalkyl, halogen, alkoxy, aryl,
arylalkyl, aralkoxy and the like).
[0021] The term "alkylene" refers to a divalent straight or
branched saturated hydrocarbon radical such as, for example,
--CH.sub.2--, --CH.sub.2CH.sub.2--, --CH.sub.2CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH(CH.sub.3)CH2-,
--CH.sub.2CH(CH.sub.2CH.sub.3)CH.sub.- 2CH(CH.sub.3)CH2-, and the
like.
[0022] The term "halo" refers to fluoride, chloride, bromide, and
iodide radicals.
[0023] The term "haloalkyl" refers to an alkyl group substituted
with a halo radical.
[0024] The term "hydroxyalkyl" refers to an alkyl group substituted
with a hydroxyl moiety.
[0025] The term "aryl" refers to monovalent unsaturated aromatic
carboxylic radicals having a single ring (for example, phenyl) or
multiple condensed rings (for example, naphthyl or anthryl), which
can be optionally substituted by substituents such as halogen,
alkyl, arylalkyl, alkoxy, aralkoxy, and the like.
[0026] The term "alkoxy" refers to --O-alkyl. Alkoxy groups
include, for example, methoxy, ethoxy, propoxy, isopropoxy, and the
like.
[0027] The term "aralkyl" refers to an aryl radical substituted
with an alkyl radical (for example, aryl-alkyl-). Aralkyl groups
include, for example, phenethyl, benzyl, and naphthethyl.
[0028] The term "alkaryl" refers to an alkyl radical bonded to an
aryl radical, thus producing a divalent moiety (for example,
alkyl-aryl-).
[0029] The term "aralkylene" refers to an aryl radical substituted
with an alkylene radical, thus producing a divalent moiety (for
example, -aryl-alkyl-). Aralkylene groups include, for example,
phenethyl, benzyl, and naphthethyl.
[0030] Preparation of Yellow-Green Acrylate Functional Fluorescent
Dyes
[0031] A method for preparing the yellow-green acrylate functional
fluorescent dyes is, for example, as follows: 6
[0032] Typically, 4-chloronaphthalic anhydride (1) is used as a
starting material. This material can be reacted with
2-aminothiophenol to yield a thioether (2). Further reaction of the
thioether (2) in an acidified polar aprotic solvent with sodium
nitrite results in the corresponding thioxanthene derivative (3).
The thioxanthene derivative (3) can then be further reacted with an
alkanol amine to form the imide derivative of the thioxanthene (4).
The imide derivative (4) can then be (meth)acrylate functionalized
using methods known in the art such as, for example, by
esterification using reagents such as (meth)acrylic acid or
(meth)acryloyl chloride to form the resulting yellow-green
fluorescent dye (YGFD).
[0033] Alternatively, vinyl ethers can be prepared by reacting
vinyl acetate with (4) in the presence of a mercury catalyst, or
allyl ethers can be prepared by reacting allyl bromide with (4) in
the presence of a base.
[0034] Preparation of Red Acrylate Functional Fluorescent Dyes
[0035] A method for preparing the red acrylate functional
fluorescent dyes is, for example, as follows: 7
[0036] Typically, 2-hyroxybenzanthrone (5) is used as a starting
material. This material can be reacted in polar aprotic solvents
using hydroxylating reagents such as ethylene carbonate, alkyl
diols, or hydroxy alkyl halides to form an alkylenyl hydroxy
structure (6). The alkenyl hydroxy(6) can then be brominated at the
3-position using a brominating agent such as n-bromosuccinimide in
polar aprotic solvents. The resulting brominated species (7) can be
reacted with a 2-aminothiophenol to produce a thioether (8). The
thioether (8) can then be reacted with hydrochloric acid and sodium
nitrite to yield the corresponding thioxanthene derivative (9). The
thioxanthene derivative can be (meth)acylate functionalized using
methods known in the art such as, for example, by esterification
using reagents such as (meth)acrylic acid or (meth)acryloyl
chloride to form the resulting red fluorescent dye (RFD).
[0037] Alternatively, vinyl ethers can be prepared by reacting
vinyl acetate with (4) in the presence of a mercury catalyst, or
allyl ethers can be prepared by reacting allyl bromide with (4) in
the presence of a base.
[0038] Dyed Polymers
[0039] The yellow-green and red fluorescent dyes of the invention
can be co-polymerized with one or more monomers to give fluorescent
oligomers or copolymers that have uniform and stable color.
[0040] Suitable monomers include any of the free radically
polymerizable ethylenically-unsaturated monomers such as, for
example, vinyl aromatic monomers, .alpha.,.beta.-unsaturated
carboxylic acids and their derivatives, vinyl esters of carboxylic
acids, N-vinyl compounds, vinyl ketones, and the like.
Representative examples of such monomers include styrene,
.alpha.-methylstyrene, (meth)acrylic acid, (meth)acrylates (as used
herein, "(meth)acrylic acid" refers to both acrylic acid and
methacrylic acid and "(meth)acrylates" refers to both acrylates and
methyacrylates) (for example, methyl methacrylate, butyl
methacrylate, 2-ethylhexyl methacrylate, ethyl acrylate, butyl
acrylate, iso-octyl acrylate, octadecyl acrylate, cyclohexyl
acrylate, phenyl acrylate, benzyl methacrylate), methacrylonitrile,
vinyl acetate, vinyl chloride, N-vinylpyrrolidone,
N-vinylcaprolactam, and the like.
[0041] Preferably, alkyl(meth)acrylate ester monomers are used.
Alkyl(meth)acrylate ester monomers useful in the invention include
straight chain, cyclic, and branched chain isomers of alkyl esters
containing alkyl groups having 1 to about 14 carbon atoms.
Representative examples of alkyl (meth)acrylate esters include
methyl methacrylate, ethyl ethyl acrylate, n-propyl acrylate,
2-butyl acrylate, iso-amyl acrylate, n-hexyl acrylate, n-heptyl
acrylate, isobornyl acrylate, n-octyl acrylate, iso-octyl acrylate,
2-ethylhexyl acrylate, iso-nonyl acrylate, decyl acrylate, undecyl
acrylate, dodecyl acrylate, tridecyl acrylate, and tetradecyl
acrylate.
[0042] Surprisingly, the yellow-green and red fluorescent dyes of
the invention can be co-polymerized with one or more fluoromonomers
to give fluorescent fluoropolymers. Examples of suitable
fluoromonomers can be represented by the following general formula:
8
[0043] wherein R.sub.7 is hydrogen, halogen, or straight chain or
branched chain alkyl containing 1 to about 4 carbon atoms; each
R.sub.8 is independently hydrogen or straight chain or branched
chain alkyl containing 1 to about 4 carbon atoms; Q is a covalent
bond or an organic linking group; and R.sub.f is a fully or
partially fluorinated fluoroaliphatic group.
[0044] Preparation of such compounds are known in the art and are
described, for example, in U.S. Pat. No. 2,803,615 (Ahlbrecht et
al.) and U.S. Pat. No. 2,841,573 (Ahlbrecht et al.), which are
incorporated herein by reference in their entirety.
[0045] Typically, the fluoromonomers useful in the invention
contain from about 5 percent to about 80 percent (preferably from
about 20 percent to about 65 percent; more preferably from about 25
percent to about 55 percent) fluorine by weight based upon the
total weight of the compound, the loci of the fluorine being
essentially in the R.sub.f groups. R.sub.f is a stable, inert,
non-polar, preferably saturated, monovalent moiety which is both
oleophobic and hydrophobic. R.sub.f preferably contains at least
about 3 carbon atoms, more preferably about 3 to about 12 carbon
atoms, and most preferably about 3 or 4 carbon atoms. R.sub.f can
be a straight chain, branched chain, or cyclic fluorinated alkylene
groups, or combinations thereof. R.sub.f is preferably free of
polymerizable olefinic unsaturation and can optionally contain
catenary heteroatoms.
[0046] It is preferred that R.sub.f contain about 35% to about 78%
fluorine by weight, more preferably about 40% to about 78% fluorine
by weight. The terminal portion of the R.sub.f group contains a
fully fluorinated terminal group such as, for example, --CF.sub.3,
CF.sub.3CF.sub.2CF.sub.2--, and (CF.sub.3).sub.2CF--, or can be
partially fluorinated such as, for example, HCF.sub.2--.
[0047] Q is a linking group that can be a covalent bond, divalent
alkylene, or a group that can result from the condensation reaction
of a nucleophile such as an alcohol, an amine, or a thiol with and
electrophile, such as an ester, acid halide, isocyanate, sulfonyl
halide, sulfonyl ester, or can result from a displacement reaction
between a nucleophile and leaving group. Q can optionally contain
one or more catenary heteroatom-containing groups. As used herein,
the term "catenary heteroatom-containing group" means a group
containing a heteroatom (for example, nitrogen, oxygen, or sulfur)
that replaces one or more carbon atoms of the Q linking group in a
manner such that the heteroatom-containing group is bonded to at
least two carbon atoms of the Q linking group.
[0048] Examples of suitable Q linking groups include straight
chain, branched chain, or cyclic aklyenes, arylenes, and
aralkylenes that optionally contain, for example, an oxy, oxo,
hydroxy, thio, sulfonyl, sulfoxy, amino, imino, sulfonamido,
carboxamido, carbonyloxy, urethaneylene, urylene, or combination
thereof (for example, sulfonamidoalkylene or polyoxyalkylene).
[0049] Representative examples of suitable Q linking groups include
the following:
1 --SO.sub.2NR.sub.1'(CH.sub.2).sub.kO(O)C--
--CONR.sub.1'(CH.sub.2).sub.kO(O)C-- --(CH.sub.2).sub.kO(O)C--
--CH.sub.2CH(OR.sub.2')CH.sub.2O(O)C-- --(CH.sub.2).sub.kC(O)O--
--(CH.sub.2).sub.kSC(O)-- --(CH.sub.2).sub.kO(CH.sub.2).sub.kO(O)C-
-- --(CH.sub.2).sub.kS(CH.sub.2).sub.kO(O)C--
--(CH.sub.2).sub.kSO.sub.2(CH.sub.2).sub.kO(O)C--
--(CH.sub.2).sub.kS(CH.- sub.2).sub.kOC(O)--
--(CH.sub.2).sub.kSO.sub.2NR.sub.1'(CH.sub.2).s- ub.kO(O)C--
--(CH.sub.2).sub.kSO.sub.2-- --SO.sub.2NR.sub.1'(CH.sub-
.2).sub.kO-- --SO.sub.2NR.sub.1'(CH.sub.2).sub.k--
--(CH.sub.2).sub.kO(CH.sub.2).sub.kC(O)O--
--CH.sub.2).sub.kSO.sub.2NR.su- b.1'(CH.sub.2).sub.kC(O)O--
--(CH.sub.2).sub.kSO.sub.2(CH.sub.2).su- b.KC(O)O--
--CONR.sub.1'(CH.sub.2).sub.kC(O)O--
--(CH.sub.2).sub.kS(CH.sub.2).sub.kC(O)O--
--CH.sub.2CH(OR.sub.2')CH.sub.- 2C(O)O--
--SO.sub.2NR.sub.1'(CH.sub.2).sub.kC(O)O --(CH.sub.2).sub.kO--
--(CH.sub.2).sub.kNR.sub.1'C(O)O--
--OC(O)NR.sub.1'(CH.sub.2).sub.k--
[0050] wherein each k is independently an integer of 0 to about 20,
R.sub.1' is hydrogen, phenyl, or alkyl containing 1 to about 4
carbon atoms, and R.sub.2' is alkyl-containing 1 to about 20 carbon
atoms. Each structure is non-directional, that is,
--(CH.sub.2).sub.kC(O)O-- is equivalent to
--O(O)C(CH.sub.2).sub.k--.
[0051] Useful fluoromonomers include general classes such as
(meth)acrylates, vinyl ethers, and allyl compounds containing
fluorinated sulfonamido groups, (meth)acrylates derived from
fluorochemical telomer alcohols, fluorochemical thiols, and the
like. Representative examples of useful fluoromonomers include, for
example, 1,1-dihydroperfluorobutyl(met- h)acrylate,
1,1-dihydropentafluoropropyl(meth)acrylate, hexafluoroisopropyl
(meth)acrylate, 2,2,3,3,4,4,4-heptafluorobutyl (meth)acrylate,
2,2,3,4,4,4-hexafluorobutyl(meth)acrylate,
2,2,3,3-tetrafluoropropyl(meth)acrylate,
1,1-dihydroperfluorocyclohexylme- thyl(meth)acrylate,
1-pentafluoroethyl-2-(trifluoromethyl)propyl(meth)acry- late,
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl
(meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl
(meth)acrylate, N-methyl perfluorooctanesulfonamidoethyl
(meth)acrylate, N-ethyl perfluorohexylsulfonamidoethyl
(meth)acrylate, N-methyl perfluorooctanesulfonamidoethyl
(meth)acrylate, N-ethyl perfluorooctanesulfonamidoethyl
(meth)acrylate, N-ethyl perfluorohexylsulfonamidoethyl
(meth)acrylate, N-methyl perfluorobutanesulfonamidoethyl
(meth)acrylate, the reaction product of isocyanatoethyl
methacrylate and N-methylperfluorooctanesulfonamidoethyl alcohol,
N-methyl perfluorooctanesulfonamidoethyl vinyl ether, and
tetrameric hexafluoropropyleneoxide dihydroacrylate.
[0052] Preferably, the dyed fluoropolymers of the invention
comprise at least one (meth)acrylate fluoromonomer. More
preferably, the dyed fluoropolymers comprise N-methyl
perfluorobutanesulfonamidoethyl acrylate and/or N-methyl
perfluorobutanesulfonamidoethyl methacrylate.
[0053] Dye loading in the dyed polymers of the invention generally
varies depending upon the final application of the coating.
Typically, however, the dyed fluoropolymers of the invention
contain between about 0.001 and 3.0 weight percent of
(meth)acrylate functional dye based upon the total polymeric
content of the composition (preferably between about 0.01 and 2.0
weight percent).
[0054] The dyed polymers of the invention can be prepared by free
radical solution polymerization of the starting monomers with a
fluorescent functional dye of the invention in any conventional
solvent, including both fluorinated and non-fluorinated solvents.
Typically, the dye is dissolved into the melted monomers before the
solvent is added.
[0055] Preferably fluorinated solvents are used. More preferably,
non-ozone depleting, non-flammable, and fast drying partially
fluorinated (rather than perfluorinated) solvents such as, for
example, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons
(HFCS) and hydrofluoroethers (HFEs) are used. As used herein, the
term "hydrofluorocarbon" means compounds consisting only of the
elements carbon, hydrogen and fluorine, the term
"hydrochlorofluorocarbon" means compounds consisting only of the
elements carbon, hydrogen, fluorine and chlorine, and the term
"hydrofluoroether" means compounds that contain carbon, hydrogen,
fluorine, and at least one ether oxygen, and are free of chlorine,
bromine and iodine. Most preferably, one or more hydrofluoroethers
or mixtures of one or more hydrofluoroethers with one or more other
hydrofluorocarbons such as, for example,
CF.sub.3CH.sub.2CF.sub.2CH.sub.3 are used.
[0056] Representative examples of hydrofluoroethers suitable for
use in the invention include n-C.sub.4F.sub.9OCH.sub.3,
n-C.sub.4F.sub.9OCH.sub.- 2CH.sub.3,
CF.sub.3CF(CF.sub.3)CF.sub.2OCH.sub.3, CF.sub.3CF(CF.sub.3)CF.s-
ub.2OC.sub.2H.sub.5, C.sub.8F.sub.17OCH.sub.3, CH.sub.3O--
(CF.sub.2).sub.4--OCH.sub.3, C.sub.5F.sub.11OC.sub.2H.sub.5,
C.sub.3F.sub.7OCH.sub.3, CF.sub.3OC.sub.2F.sub.4OC.sub.2H.sub.5,
C.sub.3F.sub.7OCF (CF.sub.3)CF.sub.2OCH.sub.3,
(CF.sub.3).sub.2CFOCH.sub.- 3,
C.sub.4F.sub.9OC.sub.2F.sub.4OC.sub.2F.sub.4OC.sub.2H.sub.5, and
C.sub.4F.sub.9O(CF.sub.2).sub.3OCH.sub.3.
[0057] Typically, an initiator is used to initiate polymerization.
A wide range of molecules (for example, monoperoxycarbonates and
peroxydicarbonates, perisononanoate, tert-amyl and
tert-butylperesters, tert-amyl and tert-butyl perketal,
bisperoxides, diazo compounds, and others) can be used as free
radical sources for the initiation of polymerization.
[0058] The dyed polymers of the invention can be used in coating
compositions. An advantage of the invention is that the fluorescent
dyes can be used in detecting the uniformity and thickness of the
coating. A further advantage is that the fluorescent dyes provide
stable, non-leaching color that can be used for decorative
purposes.
[0059] Coating compositions comprising the dyed fluoropolymers of
the invention can further comprise a solvent. Any solvent in which
the dyed polymer dissolves to a suitable degree, which does not
deleteriously affect the substrate, and which does not leave a
harmful residue can be used. It is preferable, however, to use the
same solvent that was used in the polymerization reaction.
Therefore, preferences for coating solvents are the same as the
preferences stated for polymerization solvents.
[0060] Typically, the coating composition comprises up to about 50
weight percent dyed fluoropolymer (preferably up to about 35 weight
percent; most preferably up to about 28 weight percent). The
resulting coatings are generally less than about 3 mils (0.08 mm)
thick, but the desired thickness depends upon the specific
application. Thicker or thinner coatings can be prepared if
desired. The coating composition can be applied to a substrate or
article using any suitable means known in the art such as, for
example, brushing, dipping, spraying, and flow coating.
[0061] Circuit board components and assemblies can be coated with
the present dyed coating compositions to form films (sometimes
referred to as conformal coatings), which insulate them from
contaminants and preserve their electronic functions. Circuit board
assemblies can be coated before or after the components have been
mounted, but they are typically conformally coated after they have
been completely assembled and soldered. Proper coverage and
uniformity of the conformal coating over the assembly is critical
for effective protection of the assembly. Following application of
the coating composition to the assembly, the composition is dried
and/or cured to yield the resultant film.
[0062] The addition of the fluorescent dyes of the invention into
conformal coating compositions aids in the quality assurance
inspection of the circuit board assembly for proper coverage of the
coating. The fluorescent dyed polymers of the invention can be
readily observed by the human eye using, for example, "black light"
or on-line with an electro-optical device. The coating thickness
(or coating weight) can be measured on-line using techniques in
which the dye is excited by optical radiation and the thickness of
the coating is determined by the magnitude of the emitted
fluorescent radiation.
[0063] The dyed coating compositions of the invention can also be
used in many other applications where it is desirable for the
coating to have color for either decoration or detection. An
advantage of the present dyed coating compositions is their high
wetfastness properties, which are attributed to the covalent
bonding of the dye to the polymer matrix. This is an advantage over
coating compositions containing dyes fixed through adsorption or
blending and makes the dyed coating compositions of the invention
highly suitable for applications where toxicity is an issue such
as, for example, in medical and food packaging applications.
EXAMPLES
[0064] The invention will be further explained by the following
illustrative examples which are intended to be non-limiting.
2 Glossary Table Description, Formula Descriptor and/or Structure
Availability Acryloyl chloride CH.sub.2.dbd.CHCOCl Sigma- Aldrich,
Milwaukee, WI AD-1 9 See preparation below where n = 4 AD-4 10 See
preparation below where n = 1 AD-5 11 See preparation below where n
= 7 AD-6 12 See preparation below where n = 1 AD-7 13 See
preparation below where n = 5 5-amino-1-pentanol
NH.sub.2(CH.sub.2).sub.5OH Sigma-Aldrich 2-amino-1-ethanol
NH.sub.2(CH.sub.2).sub.2OH Sigma-Aldrich 6-amino-1-hexanol
NH.sub.2(CH.sub.2).sub.6OH Sigma-Aldrich 2-aminothiophenol 14
Sigma-Aldrich BMA Butyl methacrylate Sigma-Aldrich
4-chloronaphthalic anhydride 15 Acros Organics, Pittsburgh, PA
8-chloro-1-octanol Cl(CH.sub.2).sub.8OH Sigma-Aldrich DMF
dimethylformamide; Sigma-Aldrich (CH.sub.3).sub.2NC(O)H ethylene
carbonate 16 Sigma-Aldrich HFE-7100 3M .TM. NOVEC .TM. HFE-7100; 3M
Company, C.sub.4F.sub.9OCH.sub.3 perfluorobutyl St.Paul, MN methyl
ether HFE-7200 3M .TM. NOVEC .TM. FLUID HFE-7200; 3M Company
C.sub.4F.sub.9OC.sub.2H.sub.5 perfluorobutyl ethyl ether HFE-72DE
3M .TM. NOVEC .TM. HFE-72DE (HFE- 3MCompany 7100 (10%) , HFE-7200
(20%) , and trans- dichloroethylene (70%)) 2-hydroxy benzanthrone
17 Can be prepared according to U.S. Pat. No. 4,036,859 (Example 1
and 2) LMA Lauryl methacrylate Sigma-Aldrich LUPEROX Luperox .TM.
26M50, t-butyl Atofina Chem., peroctoate (50%) Philadelphia, PA MAA
Methacrylic acid Sigma-Aldrich NBS N-bromosuccinimide Sigma-Aldrich
sodium nitrite NaNO.sub.2 Sigma-Aldrich tetraethyl ammonium
(C.sub.2H.sub.5).sub.4NI Sigma-Aldrich iodide triethyl amine
N(C.sub.2H.sub.5).sub.3 Sigma-Aldrich
[0065] Preparation 1: Synthesis of MeFBSEA
[0066] Ethoxylation of MeFBSA with Ethylene Carbonate
[0067] Reaction:
C.sub.4F.sub.9SO.sub.2NHCH.sub.3+(CH.sub.2O).sub.2C.dbd.O+Na.sub.2CO.sub.3
(catalyst).fwdarw.C.sub.4F.sub.9SO.sub.2N(CH.sub.3)CH.sub.2CH.sub.2OH+CO.-
sub.2
[0068] Charges:
[0069] A. 100 g MeFBSA (C.sub.4F.sub.9SO.sub.2NHCH.sub.3, MW=313,
0.32 moles)
[0070] B. 2.8 g Na.sub.2CO.sub.3 (0.026 moles)
[0071] D1. 8 g ethylene carbonate (MW=88) (available from
Sigma-Aldrich, Milwaukee, Wis.) melted in oven at 50.degree. C.
[0072] D2. 8 g ethylene carbonate
[0073] D3. 8 g ethylene carbonate
[0074] D4. 10 g ethylene carbonate (total weight=34 g, 0.38
moles)
[0075] E. 300 ml water
[0076] F. 300 ml water
[0077] G. 300 ml 3 wt % sulfuric acid
[0078] H. 300 ml water
[0079] I. 300 ml water
[0080] J. 300 ml water
[0081] Procedure:
[0082] 1. Charges A and B were placed in a one liter 3-necked flask
with an overhead stirrer, thermocouple, addition funnel, and reflux
condenser.
[0083] 2. The batch was heated to 60.degree. C. (140.degree. F.) at
which point the batch was molten and stirring was begun. The set
point was increased to 120.degree. C. (248.degree. F.).
[0084] 3. When the batch reached 120.degree. C., Charge D1 was
removed from the oven and transferred to the addition funnel.
Charge D1 was then added slowly over a period of 10 minutes.
Outgasing (carbon dioxide) was observed. Thirty minutes elapsed
until the rate of outgasing was noticed to have diminished.
[0085] 4. Charge D2 was then transferred to the addition funnel and
added over a period of 5 minutes. After 25 minutes, the rate of
outgasing had slowed and Charge D3 was added over a 5 minute
period. After 30 minutes, Charge D4 was removed from the oven,
added to the addition funnel, and added to the batch over a 5
minute period.
[0086] 5. The set point was reduced to 110.degree. C. (230.degree.
F.) and allowed to stir overnight.
[0087] 6. In the morning, the batch was cooled to 90.degree. C.
(194.degree. F.) and the batch was sampled. Gas chromatographic
(GC) analysis showed the material to be 96.1% desired product and
to contain no amide. Charge E was added. The batch was stirred for
30 minutes, allowed to phase split and the upper water phase was
vacuum decanted off. The operation was repeated for Charge F at
63.degree. C. (145.degree. F.).
[0088] 7. The batch was then agitated with Charge G for 30 minutes
at 63.degree. C. (145.degree. F.), then was phase split, and vacuum
decanted. The pH of the water layer was tested and found to be less
than 2.
[0089] 8. The batch was then washed with water charges H, I, and J
successively at 63.degree. C. (145.degree. F.).
[0090] 9. The batch was melted and poured out of the flask into a
bottle and allowed to solidify. A small amount of water on top of
the resulting solid was poured off, and the remaining solid
material in the jar was found to weigh 124 g.
[0091] 10. The solid material was melted into a two-necked 500 ml
flask. The melting point was found to be 57.degree. C. (135.degree.
F.).
[0092] 11. The resulting liquid material (113 g) was distilled at
667-933 Pa (5-7 torr Hg). 104 g (92% of undistilled material)
distilled at a head temperature of 130-137.degree. C.
(266-279.degree. F.) and a pot temperature of 136-152.degree. C.
(277-306.degree. F.). Further increase of the pot temperature to
170.degree. C. (338.degree. F.) resulted in no further material
distilling over.
Preparation of MeFBSEA (N-methyl-(perfluorobutanesulfonamido)ethyl
acrylate)
[0093] Reaction:
C.sub.4F.sub.9SO.sub.2N(CH.sub.3)CH.sub.2CH.sub.2OH+CH.sub.2.dbd.CHCO.sub.-
2H+triflic acid (CF.sub.3SO.sub.3H)
catalyst.fwdarw.C.sub.4F.sub.9SO.sub.2-
N(CH.sub.3)CH.sub.2CH.sub.2C(.dbd.O)CH.dbd.CH.sub.2+H.sub.2O+CF.sub.3SO.su-
b.3H
[0094] Charges:
[0095] A. 112 g MeFBSE alcohol
(C.sub.4F.sub.9SO.sub.2N(CH.sub.3)CH.sub.2C- H.sub.2OH, 0.313
moles)
[0096] B. 0.07 g phenothiazine (available from Sigma-Aldrich,
Milwaukee, Wis.)
[0097] C. 0.11 g methoxyhydroquinone (MEHQ) (available from
Sigma-Aldrich, Milwaukee, Wis.)
[0098] D. 100 g heptane
[0099] E. 27.5 g acrylic acid (0.38 moles)
[0100] F. 1 g anhydrous triflic (trifluoromethanesulfonic) acid
(available as FC-24 from 3M, St. Paul, Minn.)
[0101] G. 300 g water
[0102] H. 300 g water
[0103] Procedure:
[0104] 1. Charges A, B, C, D, E and F were added to a 3-necked
flask equipped with decanter assembly, overhead stirrer, and a
thermocouple under positive nitrogen pressure.
[0105] 2. The flask was warmed to 60.degree. C. and the stirring
was begun. The batch was stirred at reflux which was initially at
96.degree. C. and rose to 102.degree. C. by the end of the
reaction. The theoretical water that should be collected in the
decanter was 6.3 ml. After 15 minutes of refluxing, 2 ml had
collected. After 1 hour and 15 minutes, the reflux temperature was
99.degree. C. and 5 ml had collected. After 5 hours and 15 minutes
the reflux temperature was 102.degree. C. and 5.4 ml had collected.
A sample was withdrawn from the batch and GC analysis showed no
unreacted alcohol, 92.6% desired product and 7.4% high boiler.
[0106] 3. The batch was stripped atmospherically to the decanter
until at 103.degree. C. no more heptane collected in it.
[0107] 4. The batch was cooled to 64.degree. C. and vacuum was
pulled slowly. More heptane was stripped off until at 5 torr no
more liquid was observed to be distilling off.
[0108] 5. Vacuum was broken and Charge G was added. The batch was
stirred at 64.degree. C. for 15 minutes, allowed to phase spilt and
the upper layer was vacuumed off.
[0109] 6. This operation was repeated with Charge H and then the
batch was allowed to cool to room temperature at which point the
product was a solid. The remaining water was poured off and the
product material was melted out of the container into a jar. The
weight of the product was 125 g (theoretical 129 g). GC analysis
showed the material to be 92.64% desired acrylate and 7.36% acrylic
acid Michael adduct.
[0110] Preparation 2: Synthesis of MeFBSEMA
[0111] MeFBSEMA (N-methyl-(perfluorobutanesulfonamido)ethyl
methacrylate) was prepared as described in Preparation 1 above,
except using methacrylic acid in place of acrylic acid 18
[0112] Step A: Preparation of (2)
[0113] A 1000 mL round bottom flask equipped with a heating mantle,
stirrer and dropping funnel was charged with 4-chloronaphthalic
anhydride ((1), 125 g, 0.54 moles), potassium carbonate (36.9 g,
0.27 moles), 215 g isopropyl alcohol, and 322 g sulfolane and
heated to about 50.degree. C. 2-aminothiophenol (73.9 g moles) was
added dropwise so that the temperature was maintained below
80.degree. C. The mixture was then heated to 90.degree. C. and held
for 3 hours. The mixture was cooled to 15.degree. C. and the
resulting orange precipitate was recovered via filtration with a
Buchner funnel. The solid was resuspended in DI water (470 g) and
then filtered using a Buchner funnel. The solid was dried and
analysis via .sup.13C NMR confirmed the structure (2).
[0114] Step B: Preparation of (3)
[0115] A 5000 mL round bottom flask fitted with a dropping funnel
and immersed in an ice-water cooling bath was charged with (2)
(241.0 g, 0.75 moles) and 3600 g DMF. HCl (600 g, concentrated) was
slowly added dropwise, keeping the temperature below 15.degree. C.
An aqueous solution of sodium nitrite (52.5 g, 21%) was added and
the reaction mixture was stirred for two hours, maintaining the
temperature below 5.degree. C. CuSO.sub.4.5H.sub.2O (3.0 g, 0.012
moles) was added and a mild exotherm occurred. The cooling bath was
then replaced with a heating mantle, and nitrogen gas evolved as
the temperature was slowly elevated to 100.degree. C. and held for
3 hours. The mixture was cooled to ambient temperature
(.about.25.degree. C.) and filtered using a Buchner funnel. The
resulting solid was resuspended in DI water (1000 g) and filtered
again using a Buchner funnel. The solid (3) was dried to yield 171
g (75% of the theoretical material).
[0116] Step C: Preparation of (4)
[0117] A 1000 mL round bottom flask fitted with a condenser was
charged with (3) (40.0 g, 0.13 moles), 5-amino-1-pentanol (13.5 G,
0.13 moles) and DMF (240 g) and the ensuing mixture was heated to
reflux (.about.155.degree. C.) for 3 hours. After it was determined
that no starting material remained (via thin layer chromatography
(TLC) in ethyl acetate) the mixture was cooled to 80.degree. C. and
400 g DI water was added, keeping the temperature between
70-80.degree. C. until all the water was added. The resulting
suspension was then filtered using a Buchner funnel and the solid
material was resuspended in 500 g DI water and filtered again using
a Buchner funnel. The yield of resulting material (4) was 41 g.
[0118] Step D: Preparation of AD-1
[0119] A one liter three neck round bottom flask fitted with an
overhead stirrer and dropping funnel was charged with (4) (25.0 g;
0.062 moles), dimethyl formamide (310.0 g) and triethyl amine (8.15
g; 0.08 moles). The resulting mixture was stirred and heated to
40.degree. C. at which time acryloyl chloride (6.44 g, 0.07 moles)
was added drop wise to the mixture over 30 minutes while keeping
the temperature at approximately 40.degree. C. After two hours,
additional triethyl amine (3.0 g) and acryloyl chloride (2.2 g)
were added. The resulting mixture was stirred for another hour and
then cooled to 20.degree. C. Deionized (DI) water (500.0 g) was
added to the cooled mixture and solid AD-1 was isolated via
filtration with a Buchner funnel. AD-1 was re-suspended in DI water
(700.0 g), filtered using a Buchner funnel and air dried (yielding
24.7 g; 96% purity of AD-1. The structure and purity were confirmed
via .sup.13C nuclear magnetic resonance (NMR) analysis. 19
[0120] Step 1: Preparation of (11)
[0121] A 1 L three neck round bottom flask equipped with a
mechanical stirrer and thermometer was charged with 2-hydroxy
benzanthrone ((10), 75.0 g; 0.3 mole), ethylene carbonate (35.0 g;
0.4 mole), tetraethylammonium iodide (18.0 g; 0.07 mole) and
dimethylformamide (300.0 g). The ensuing mixture was heated at
reflux for 15 hours, and additional ethylene carbonate (25.0 g; 0.3
mole) and tetraethylammonium iodide (8.0 g; 0.03 mole). The
resulting mixture was cooled to ambient temperature and DI water
was added (200.0 g). The precipitate was filtered, allowed to air
dry and recrystallized in isopropyl alcohol (yielding 70 g. of
(11)).
[0122] Step 2: Preparation of (12)
[0123] A 1 L three neck round bottom flask equipped with a
mechanical stirrer and condenser was charged with 11 (70.0 g; 0.24
mole), NBS (53.0 g; 0.3 mole) and dimethylformamide (500.0 g). The
ensuing stirred mixture was heated to about 55.degree. C. for 3
hours, cooled to ambient temperature and DI water (500.0 g) was
added. The aqueous mixture was extracted with chloroform (250.0 g).
This organic extract was then washed three times with DI water
(500.0 g aliquots), chloroform was removed using a rotary
evaporator, and the resulting yellow material (12) was oven dried
(75 g; 88% yield).
[0124] Step 3: Preparation of (13)
[0125] A 500 mL three neck round bottom flask equipped with a
mechanical stirrer and condenser was charged with 12 (73.0 g; 0.2
mole), sodium carbonate (14.4 g; 0.13 mole), 2-aminothiophenol
(27.5 g; 0.22 mole) and dimethylformamide (300.0 g). The ensuing
mixture was stirred and heated at reflux for 3 hours, cooled to
ambient temperature, and filtered. The yellow solid material was
washed with DI water (20.0 g), filtered and oven dried to yield
(13) (22.0 g; 22% yield).
[0126] Step 4: Preparation of (14)
[0127] A 1 L three neck round bottom flask equipped with a
mechanical stirrer and dropping funnel was charged with (13) (20.6
g; 0.05 mole) and dimethylformamide (300.0 g). The ensuing mixture
was cooled to 20.degree. C. using an ice bath, and HCl (55.0 g;
concentrated) was slowly added dropwise, keeping the temperature at
or below 20.degree. C. With continued cooling, an aqueous solution
of sodium nitrite (24.0 g; 16.6%) was added dropwise over a period
of one hour, keeping the temperature at or below 5.degree. C. Upon
completion of the addition, the cooled mixture was stirred for an
additional 2 hours. The cooling bath was removed and replaced with
a heating mantle. Cu(SO.sub.4).sub.2 (0.3 g) was added to the
mixture and a temperature of 130.degree. C. was maintained for 3
hours. The mixture was then cooled to ambient temperature and
filtered. The filtered solid was re-slurried with DI water (200.0
g), filtered and oven dried to yield (14) (14.0 g; 71% yield; mp
301-303.degree. C.). Structure and purity (>90%) were confirmed
using .sup.13C NMR.
[0128] Step 5: Preparation of AD-4
[0129] A 1 L three neck round bottom flask equipped with a
mechanical stirrer and dropping funnel was charged with (14) (25.0
g; 0.063 mole) dimethylformamide (690 g.) and triethyl amine (7.65
g; 0.075 mole). The ensuing stirred mixture was heated to
40.degree. C. and acryloyl chloride (6.3 g; 0.07 mole) was added
dropwise over 0.5 hour. The resulting mixture was maintained at
40.degree. C. for 3 hours, cooled to 20.degree. C. in an ice bath,
and DI water (500.0 g) was added. The precipitate was filtered from
the filtrate using a Buchner funnel and the solid was washed three
times with DI water (500.0 g each aliquot) to yield a AD-4 (35.0
g). Structure and purity (>95%) were confirmed using .sup.13C
NMR. 20
[0130] The preparation of AD-5 (where n=7) essentially follows the
description of the preparation for AD-4 (where n=1) above with the
exception that Step A was replaced by the following:
[0131] A 500 mL three neck round bottom equipped with a mechanical
stirrer, condenser and addition funnel was charged with 1 (30.0 g;
0.12 mole), DI water (200 g.) NaI (1.8 g; 0.12 mole) and aqueous
NaOH in (19.4 g; 50%). The stirred mixture was heated to reflux and
8-chloro-1-octanol (40.1 g, 0.24 mole) was added dropwise over 1.5
hours. The temperature was maintained for 2 additional hours, then
cooled to ambient temperature, filtered and the resulting solid
(15) was air dried (35.8 g). The stoichiometric equivalent of this
material was then used in the succeeding steps outlined above to
ultimately yield AD-5 (where n=7). 21
[0132] AD-7 was prepared essentially according to the preparation
followed for synthesis of AD-1 with the exception that in Step C,
2-amino-1-ethanol (0.13 moles) was used instead of
5-amino-1-pentanol. In the synthesis of the acrylate dye, AD-6, a
stoichiometric equivalent of 19 was used. 22
[0133] AD-7 was prepared essentially according to the preparation
followed for synthesis of AD-1 with the exception that in Step C,
6-amino-1-hexanol (0.13 moles) was used instead of
5-amino-1-pentanol. In the synthesis of the acrylate dye, AD-6, a
stoichiometric equivalent of 20 was used.
[0134] Coating and Test Methods
[0135] Dip Coating Method
[0136] Each substrate (described below) was wiped with ethanol
using a Kimwipe.TM. sheet (available from Kimberly Clark, Roswell,
Ga.) and then ultrasonically treated in a warm bath of HFE-72DE for
about 5 minutes, removed, and allowed to air dry at ambient
conditions. The substrates were then dipped into solutions of the
fluoropolymer to be tested and withdrawn at a constant rate of 5.3
in/min (13.46 cm/min). Each coated substrate was then air dried at
ambient temperature (.about.72.degree. F. (.about.22.degree. C.))
and visually inspected for a uniform, blemish-free coating.
[0137] Coating Thickness Test Method
[0138] Coating thickness was measured with a micrometer at six
points (top 1/3, middle 1/3 and bottom 1/3) on the front and back
of each coated substrate. Average values are reported below in
Table 1.
[0139] Flexibility Test Method
[0140] Tin coated steel panels (3 inch (7.6 cm).times.5 inch (12.7
cm), 0.0107 inch (0.027 cm) thick) were coated with solutions of
fluoropolymer as described above. The coated panels were bent
180.degree. over a 0.125 inch (0.32 cm) diameter mandrel. The
coating on each panel was then visually inspected and evaluated for
cracks, crazes, or delaminations using a 6.times. magnifying loupe.
If any cracks, crazes, or delaminations were observed, the coating
failed this test. Results are reported below in Table 1.
[0141] Dielectric Withstanding Voltage Test Method
[0142] IPC-B-25A test boards (available from T.R.C. Circuits, Inc.,
Minneapolis, Minn.) were coated with solutions of fluoropolymer as
described above. The D pattern on each IPC-B-25A test board was
subjected to an increasing bias from 0 to 1500 V over 15 seconds
and then held for one minute at 1500 V. If the board exhibited
flashover, sparkover or breakdown, the coating failed this test.
Results are reported below in Table 1.
[0143] Visual Test for Coating Uniformity
[0144] Coating uniformity was qualitatively determined by placing
substrates coated as described above under a black light (Standard
fluorescent desk lamp fitted with two 18 inch (45 cm) GE 15 W
blacklights) and inspecting for fish eyes or other coating
defects.
[0145] Thermal Gravimetric Analysis (TGA)
[0146] The thermal decomposition of each conformal coating material
was determined by thermal gravimetric analysis (TGA) under an inert
nitrogen atmosphere using a 10.degree. C. per minute temperature
ramp using a Perkin Elmer Thermogravimetric Analyzer TGA 7 (Perkin
Elmer Instruments, Norwalk, Conn.). Results are shown in FIG.
1.
[0147] Solubility in Acetone
[0148] Solubility of the dyes in acetone was determined by weighing
a small amount of dye into a jar and adding small aliquots of
acetone until no undissolved dye remained. Results are listed below
in Table 2.
[0149] Solubility in Acrylate Monomer
[0150] Solubility of the dyes was determined in various acrylate
monomers using standard fluorescence measurement techniques (SPEX
Fluorolog-3 Spectrophotometer, SPEX Industries, Edison, N.J.).
Results are listed below in Table 3.
Example 1
[0151] A 600 mL Parr reactor (available from Parr Instrument Co.,
Moline, Ill.) was charged with MeFBSEA (146.30 g; 0.36 moles),
MeFBSEMA (10.03 g; 0.023 moles), BMA (3.34 g; 0.023 moles), LMA
(5.85 g; 0.023 moles), MAA (1.67 g; 0.020 moles) and AD-1 (0.011
g). Upon dissolution of the charges, LUPEROX (9.24 g) and HFE-7100
(440.80 g) were added. The reactor was then sealed and degassed
four times, by pulling a vacuum of 5-10 psig (34-68 kPa) and then
purging with nitrogen. The reactor temperature was then elevated
and held at 80.degree. C. for about 24 hours. The resulting
reaction mixture was filtered. The resulting filtered solution was
used to coat substrates for testing.
Example 2
[0152] The procedure described for Example 1 was followed for the
preparation of Example 2, with the exception that AD-1 was replaced
with AD-2 and the AD-2/polymer charge was mildly heated in an oven
to 80.degree. C.
Example 3
[0153] The procedure described for Example 1 was followed for the
preparation of Example 3, with the exception that AD-1 was replaced
with AD-3.
Comparative Example C1
[0154] Comparative Example C1 was prepared according to the
procedure described for Example 1, with the exception that the
addition of AD-1 was omitted.
3TABLE 1 Coating Dielectric Thickness Flexibility Withstand Visual
Ex. Dye (mm) Test Test Test 1 AD-1 0.0464 Passed Passed Passed 2
AD-2 0.0474 Passed Passed Passed 3 AD-3 0.0489 Passed Passed Passed
C1 No dye 0.0468 Passed Passed Passed
[0155]
4TABLE 2 Solubility of dye in acetone Solubility Dye (g acetone/mg
of dye) AD-1 0.83 AD-4 11.0 AD-5 0.65 AD-6 11.6 AD-7 0.83
[0156]
5TABLE 3 Solubility of dyes in acrylate monomers Solubility (.mu.g
dye/ mL of acrylate Dye Acrylate Monomer monomer AD-6 LMA 227 AD-7
LMA 114 AD-1 LMA 816 AD-6 BMA 559 AD-7 BMA 301 AD-1 BMA 1217
* * * * *