U.S. patent application number 12/122989 was filed with the patent office on 2008-09-04 for surfactant composition having stable hydrophilic character.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Yolla B. Levitt, Matthew T. Scholz.
Application Number | 20080213595 12/122989 |
Document ID | / |
Family ID | 34520949 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080213595 |
Kind Code |
A1 |
Levitt; Yolla B. ; et
al. |
September 4, 2008 |
SURFACTANT COMPOSITION HAVING STABLE HYDROPHILIC CHARACTER
Abstract
Hydrophilic surfactant compositions are disclosed that include a
surfactant component and a stabilizer component. The surfactant can
be coated on a surface by depositing a surfactant solution on at
least a portion of the surface, then drying the surfactant solution
to form the dry coating. The surfactant compositions, when applied
to a substrate, can provide a hydrophilic surface that retains its
hydrophilic character over time, at elevated temperatures, or
both.
Inventors: |
Levitt; Yolla B.; (Mendota
Heights, MN) ; Scholz; Matthew T.; (Woodbury,
MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
34520949 |
Appl. No.: |
12/122989 |
Filed: |
May 19, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10687340 |
Oct 17, 2003 |
7378451 |
|
|
12122989 |
|
|
|
|
Current U.S.
Class: |
428/411.1 ;
427/384 |
Current CPC
Class: |
B01L 3/502707 20130101;
C08K 5/05 20130101; Y10T 428/31511 20150401; C09D 7/45 20180101;
C08K 5/005 20130101; Y10T 428/31504 20150401; B01L 2300/161
20130101; C09D 5/024 20130101 |
Class at
Publication: |
428/411.1 ;
427/384 |
International
Class: |
B32B 9/00 20060101
B32B009/00; B05D 3/02 20060101 B05D003/02 |
Claims
1. A microfluidic device for exposure to body fluids, comprising a
substrate; a coating comprising a surfactant component from about
25% to 95% by weight on a solvent-free basis and a stabilizer
component from about 5% to 75% by weight on a solvent-free basis;
wherein the contact angle of the coating does not exceed 25 degrees
after aging for thirteen weeks at 25.degree. C.
2. The microfluidic device of claim 1, wherein the substrate is
non-porous.
3. The microfluidic device of claim 1, wherein the substrate is a
film.
4. The microfluidic device of claim 1 wherein the surfactant
component is a liquid at temperatures below 25.degree. C.
5. The microfluidic device of claim 1 wherein the surfactant
component is a nonionic surfactant.
6. The microfluidic device of claim 1 wherein the surfactant
component is selected from the group consisting of alkoxylated
alkyl diol; alkoxylated alkyacetylenic diol; alkoxylated glycerin
monoester of an alkyl alcohol; alkoxylated glycerin monoester of an
aralkyl alcohol; alkoxylated alkyl alcohol; polyalkoxylated aralkyl
alcohol; silicone copolyol; polyethoxylated phenol; a fatty acid
ester of a polyalkoxylated diol; a fatty acid ester of a
polyalkoxylated triol, and polyalkoxylated
perfluoroalkyl-containing surfactant.
7. The microfluidic device of claim 1 wherein the stabilizer
component has a melting point greater than 25.degree. C.
8. The microfluidic device of claim 1 wherein the stabilizer
component has a melting point of at least 45.degree. C.
9. The microfluidic device of claim 1 wherein the stabilizer
component is selected from the group consisting of anionic
perfluoroalkyl-containing surfactant; alkyl, aralkyl or alkaryl
sulfonate; alkyl, aralkyl or alkaryl sulfate; alkyl, aralkyl or
alkaryl phosphonate; alkyl, aralkyl or alkaryl phosphate; aralkyl
or alkaryl phosphonate; alkyl, aralkyl or alkaryl betaine; aralkyl
or alkaryl phosphonate sultaine; and fatty imidazolines and
derivatives thereof.
10. The microfluidic device of claim 1 wherein the hydrophilic
characteristics indicated by the spreading drop diameter retaining
at least 90% of the original drop diameter after 3 weeks of aging
at 23.degree. C. and 50% relative humidity.
11. The microfluidic device of claim 1 wherein the hydrophilic
characteristics indicated by the spreading drop diameter retaining
at least 95% of the original drop diameter after 3 weeks of aging
at 23.degree. C. and 50% relative humidity.
12. A method of making a hydrophilic surface on a substrate,
comprising: Combining a surfactant component from about 0.2% to
0.6%, a stabilizer component from about 0.05% to 0.5%; and a
solvent to form a surfactant composition, Applying the surfactant
composition to a substrate, and Drying the surfactant composition
on the substrate, wherein the surfactant composition free of the
solvent when dried and coated on a substrate comprises the
surfactant and stabilizer in a ratio of 0.2:1 to 12:1 wt/wt and
wherein the hydrophilic characteristics indicated by a Spreading
Drop Test retain at least 85% of the original spreading drop
diameter after 3 weeks of aging at 23.degree. C. and 50% relative
humidity.
13. The method of claim 12, wherein the substrate is
non-porous.
14. The method of claim 12, wherein the substrate is a film.
15. The method of claim 12 wherein the solvent comprises a mixture
of water and alcohol.
16. The method of claim 12 wherein the alcohol is selected from the
group consisting of methanol, ethanol, 1-propanol, 2-propanol, and
butanol.
17. The method of claim 12 wherein the surfactant component is a
nonionic surfactant.
18. The method of claim 12 wherein the surfactant component is
selected from the group consisting of alkoxylated alkyl diol;
alkoxylated alkyacetylenic diol; alkoxylated glycerin monoester of
an alkyl alcohol; alkoxylated glycerin monoester of an aralkyl
alcohol; alkoxylated alkyl alcohol; polyalkoxylated aralkyl
alcohol; silicone copolyol; polyethoxylated phenol; a fatty acid
ester of a polyalkoxylated diol; a fatty acid ester of a
polyalkoxylated triol, and polyalkoxylated
perfluoroalkyl-containing surfactant.
19. The method of claim 12 wherein the stabilizer component has a
melting point greater than 25.degree. C.
20. The method of claim 12 wherein the stabilizer component is
selected from the group consisting of anionic
perfluoroalkyl-containing surfactant; alkyl, aralkyl or alkaryl
sulfonate; alkyl, aralkyl or alkaryl sulfate; alkyl, aralkyl or
alkaryl phosphonate; alkyl, aralkyl or alkaryl phosphate; aralkyl
or alkaryl phosphonate; alkyl, aralkyl or alkaryl betaine; aralkyl
or alkaryl phosphonate sultaine; and fatty imidazolines and
derivatives thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 10/687,340, filed Oct. 17, 2003, now allowed, which will issue
as U.S. Pat. No. 7,378,451 on May 27, 2008, the disclosure of which
is incorporated by reference in its entirety herein.
BACKGROUND OF THE INVENTION
[0002] Surfactant coatings for surfaces have many utilities
including fluid transport, anti-fog coatings, anti-splash coatings,
wetting, foam control, and the like. Surfactants can provide a
surface with desirable physical or chemical properties not provided
by an underlying substrate surface.
[0003] For example, certain devices such as diagnostic test devices
can be constructed with a substrate made from one or more materials
that do not promote transport of fluids such as aqueous solutions
to an extent sufficient to provide the device with a desired level
of performance, even though the substrate materials provide other
desirable qualities to the device. Thus, a surfactant coating on at
least a portion of the device can provide physical or chemical
properties that promote fluid transport and, therefore, improve
performance of the device.
[0004] Surfactants can provide a hydrophilic surface to a substrate
that promotes fluid transport over a portion of the substrate
coated with the surfactant. Such hydrophilic surfaces can be
provided by coatings of suitable surfactants. Suitable surfactants
include, but not limited to, alkoxylated hydrocarbon alcohols;
polyalkylene glycol hydrocarbon ethers and esters; silicone
copolyols; polyethoxylated phenols; fatty acid esters of
polyalkoxylates such as polyethyelene glycols; fluorochemical
surfactants such as polyalkoxylated perfluoroalkyl-containing
surfactants as well as anionic perfluoroalkyl-containing
surfactants; alkyl, aralkyl and alkaryl anionic surfactants
including sulfonates, sulfates, phosphonates and phosphates; and
alkyl, aralkyl and alkaryl amphoteric surfactants such as betaines,
sultaines, and fatty imidazolines and derivatives thereof However,
many of these surfactants may not be suitable for use in a device
that experiences extended storage periods, especially at elevated
temperatures and/or in a product construction where reagents,
adhesives, dyes, drug and excipients, or other contaminants may
exist, because the hydrophilic character provided by the surfactant
coating can dissipate over time in storage or, alternatively, at
elevated temperatures.
[0005] Therefore, a need exists for a surfactant composition useful
for forming a coating that is able to provide a hydrophilic surface
to a substrate such that the coating is able to promote fluid
transport and retains its hydrophilic character to a greater extent
than known surfactant coatings.
SUMMARY OF THE INVENTION
[0006] The present invention provides a surfactant composition
useful for forming a coating that provides a hydrophilic surface to
a substrate. The surfactant coating can promote fluid transport
while retaining its hydrophilic character over time in storage, at
elevated temperatures, and/or in a product construction where
contaminants may exist. As used herein a "contaminant" is a
component of the device which contains one or more compounds that
may be volatile or migrate (even at very low levels, e.g. as low as
part per million levels) and deposit on or interact with the coated
surfactant composition. For example, pressure sensitive or
structural adhesives are known to often contain significant levels
of monomers, catalysts, plasticizers, tackifiers, and other
components which over time can migrate and deposit on or interact
with the surfactant composition and decrease its hydrophilic
character. Other potential contaminants include reagents which may
be a part of a medical device such as a diagnostic device (e.g. a
strip to monitor glucose level, a urology strip, a pregnancy test
device and the like), dyes that may be part of indicator or other
systems, drugs and/or excipients that may be part of drug delivery
devices and similar materials.
[0007] The present invention provides a surfactant composition that
includes a surfactant component combined with a stabilizer
component. The surfactant component is generally a liquid which, in
neat form at temperatures below 45.degree. C. and preferably at
temperatures below 25.degree. C., includes an alkoxylated alkyl
diol; an alkoxylated alkyacetylenic diol; a polyalkoxylated
glycerin monoester of an alkyl or aralkyl alcohol; a
polyalkoxylated alkyl or aralkyl alcohol; a silicone copolyol; a
polyethoxylated phenol; a fatty acid ester of a polyalkoxylated
diol or triol; a fluorochemical surfactant such as a polyakoxylated
perfluoroalkyl-containing surfactant or an anionic
perfluoroalkyl-containing surfactant; an alkyl, aralkyl or alkaryl
anionic surfactant such as sulfonate, sulfate, phosphonate or
phosphate; an alkyl, aralkyl or alkaryl amphoteric surfactant such
as a betaine, sultaine, or fatty imidazolines and derivatives
thereof, or any combination of two or more of the foregoing. As
used herein, the term "alkoxylated" means that the surfactant or
stabilizer has been reacted with an alkylene oxide such that one or
more units of alkylene oxide have been covalently bonded to the
surfactant or stabilizer.
[0008] The stabilizer component includes an alkyl, aralkyl, or
alkaryl sulfonate, sulfate, phosphonate or phosphate surfactant
having from about 8 to about 24 carbon atoms that does not prohibit
the surfactant composition from providing a hydrophilic surface
and, free of any solvent, has a melting point greater than about
25.degree. C. Preferred stabilizers have alkyl, arlkyl or alkaryl
chains of 10 to 18 carbon atoms. The most preferred stabilizers
have alkyl, arlkyl or alkaryl chains of 10 to 14 carbon atoms, e.g.
12 carbon atoms. In some cases, the stabilizer component may have a
melting point greater than about 45.degree. C. when free of any
solvent. The alkyl groups may be linear, branched, cyclic or any
combination thereof.
[0009] In one aspect, the present invention relates to a surfactant
solution or emulsion in which the surfactant component and the
stabilizer component are at least partially dissolved in a solvent
or dispersed in a vehicle. In one embodiment, the surfactant
solution includes from about 0.05% to about 0.5%, by weight,
sodium, potassium or lithium salt of a branched chain
dodecylbenzene sulfonate and from about 0.10% to about 0.6%, by
weight, ethoxylated acetylenic diol, in a solvent including a
mixture of isopropyl alcohol and water. The solvent may be an
aqueous or organic solvent such as a hydroalcoholic solvent.
Therefore, once dried the coating free of volatile solvent
comprises the surfactant and stabilizer in a ratio of 0.2 to 12
wt/wt.
[0010] In another aspect, the present invention relates to a
surfactant coating that results from applying the surfactant
solution to a substrate surface, then drying the substrate, thereby
providing a dry coating that includes the surfactant component and
the stabilizer component wherein the contact angle does not exceed
25 degrees after aging for thirteen weeks at 25.degree. C.
[0011] In another aspect, the present invention provides a method
of making a hydrophilic surface on a substrate, comprising the
steps of combining a surfactant component from about 0.2% to 0.6%,
a stabilizer component from about 0.05% to 0.5%; and a solvent to
form a surfactant composition, applying the surfactant composition
to a substrate, and drying the surfactant composition on the
substrate. Once dried, the surfactant composition free of the
solvent when dried and coated on the substrate comprises the
surfactant component and stabilizer component in a ratio of 0.2:1
to 12:1 wt/wt.
[0012] In another aspect, the surfactant composition can be used as
a coating in a medical diagnostic test device with a substrate
having at least one side at least partially coated with a
hydrophilic coating comprising a surfactant component from about
0.2% to 0.6%, a stabilizer component from about 0.05% to 0.5% and a
solvent, wherein the surfactant composition free of the solvent
when dried and coated on a substrate comprises the surfactant and
stabilizer in a ratio of 0.2:1 to 12:1 wt/wt; and wherein the
hydrophilic characteristics indicated by a Spreading Drop Test
retain at least 85% of the original spreading drop diameter after 3
weeks of aging at 23.degree. C. and 50% relative humidity. The
coating can be used to contact or transport body fluids, such as
human blood, human blood components, urine, mucus, and the
like.
[0013] Various other features and advantages of the present
invention should become readily apparent with reference to the
following detailed description. In several places throughout the
specification, guidance is provided through lists of examples. In
each instance, the recited list serves only as a representative
group and should not be interpreted as an exclusive list.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Many surfactants are capable of providing a relatively
hydrophilic surface to a substrate when a coating that includes the
surfactant is applied to the substrate. The hydrophilic character
of the coated substrate can be evaluated by measuring, for example,
the wettability of the coated substrate, the contact angle of water
applied to the coated substrate, or the time required for a liquid
to traverse a known distance on the coated substrate, e.g., wicking
rate or fill time. However, surfaces coated with surfactants can
lose at least a portion of their hydrophilic properties over time
in storage or at elevated temperatures and/or in a product
construction where contaminants may exist as characterized by
decreased wettability, increased contact angle, longer times to
traverse a distance, longer times to fill a reservoir, and the
like, thereby affecting the performance of the substrate. If the
hydrophilic characteristics of the substrate are important for the
performance of a device, the performance of the device also may be
compromised. In some cases, the loss of hydrophilic character can
be pronounced in as little as twenty-four hours.
[0015] The present invention provides a surfactant composition
suitable for use as a coating on a substrate that provides the
substrate with hydrophilic character that can remain substantially
stable for an extended period, even at elevated temperatures, e.g.,
temperatures greater than about 45.degree. C. Additionally, the
surfactant composition of the present invention may provide
additional features advantageous for certain hydrophilic surfactant
coatings.
[0016] The surfactant composition of the present invention is
described below, at times, in the context of providing a
hydrophilic coating to a portion of a microfluidic device. The
device may be, for example, any device that is designed to
transport at least a portion of a liquid sample from one portion of
the device to another portion of the device. Such a device may
include one or more substrates that may be substantially flat or,
alternatively, may include structures such as channels. Such
channels may include microstructures. As used herein
"microstructure" refers to structures having the smallest
cross-sectional dimensions generally from 1 um to 1000 um and
typically from 10-500 um. For example, a channel may be 100 um deep
but can be 10 mm wide by 20 mm long and still be a
"microstructure". As used herein "microfluidic" devices are those
that incorporate microstructures at least one of which is intended
to transport fluid. A representative device may be, for example, a
diagnostic or detection device designed to detect or identify one
or more components of a liquid sample. However, the features of the
present invention are equally applicable to any article or device
that includes one or more substrates or surfaces that include a
hydrophilic coating.
[0017] In one embodiment, the present invention includes a
surfactant composition in solution. Generally, the surfactant
composition includes a surfactant component and a stabilizer
component. The stabilizer component may, itself, include a
surfactant.
[0018] The surfactant component of the surfactant composition may
include one or more surfactants that provide hydrophilic character
to the composition and, therefore, also to a coating that can
result from drying the surfactant composition that has been applied
to at least a portion of a substrate. As used herein, the term
surfactant refers to any amphipathic molecule that, when added to
water, reduces surface tension. Preferred surfactants have
molecular weights of less than about 2000 daltons, preferably less
than about 1000 daltons, and most preferably less than about 500
daltons. The surfactant component in neat form is a liquid at
temperatures below 45.degree. C. and preferably at temperatures
below 25.degree. C. Suitable surfactants for use in the surfactant
composition include, but are not limited to, nonionic surfactants
such as alkoxylated hydrocarbon alcohols; polyalkylene glycol
hydrocarbon ethers and esters; silicone copolyols; polyethoxylated
phenols; fatty acid esters of polyalkoxylates such as polyethyelene
glycols; alkoxylated alkylacetylenic diols such as those described
in U.S. Pat. No. 6,313,182, issued Nov. 6, 2001; and fluorochemical
surfactants such as polyakoxylated perfluoroalkyl-containing
surfactants. Suitable surfactants also include, but are not limited
to, anionic surfactants such as anionic perfluoroalkyl-containing
surfactants; alkyl, aralkyl and alkaryl anionic surfactants
including sulfonates, sulfates, phosphonates and phosphates; and
alkyl, aralkyl and alkaryl amphoteric surfactants such as betaines,
sultaines, and fatty imidazolines and derivatives thereof, and the
like. Other surfactants suitable in the present invention include
the anti-fog surfactants described in U.S. Pat. No. 6,040,053,
issued Mar. 21, 2000; U.S. Pat. No. 5,997,621, issued Dec. 9, 1999;
U.S. Pat. No. 5,873,931, issued Feb. 23, 1999; U.S. Pat. No.
5,753,373, issued May 19, 1998; or U.S. Pat. No. 5,723,175, issued
Mar. 3, 1998.
[0019] The stabilizer component of the surfactant composition
includes one or more compounds that extend the time period during
which the surfactant component imparts hydrophilic character to a
substrate that has been coated with the surfactant composition. The
stabilizer component may be selected so that is does not
substantially counteract the hydrophilic character of the
surfactant component and, in fact, may be selected so that it
contributes to the hydrophilic character of the surfactant
composition.
[0020] In most embodiments, the stabilizer component of the
surfactant compositions may have a melting point greater than about
23.degree. C. In certain embodiments, the stabilizer component may
have a melting point greater than 35.degree. C., and preferably at
least 45.degree. C. In some embodiments, the stabilizer component
may contribute to the hydrophilic character of the surfactant
composition.
[0021] In some embodiments, the stabilizer component includes an
anionic surfactant. In many embodiments, the stabilizer component
includes an alkali metal salt of an alkyl, alkyl, alkaryl, or
aralkyl sulfate or sulfonate having 8-24 carbon atoms such as an
alkali metal salt of dodecylbenzene sulfonate, e.g., sodium,
potassium or lithium salt of dodecylbenzene sulfonate. One
preferred embodiment includes sodium dodecylbenzene sulfonate.
Alkoxylated derivatives of alkyl, aralkyl, or alkaryl sulfonate,
sulfate, phosphonate or phosphate surfactants are also useful as
the stabilizer component. Preferred stabilizer components have less
than 20, and more preferably less than 10 moles of ethoxylation per
mole of alkyl, alkaryl or aralkyl group. Examples include sodium
laureth-2-sulfate, sodium lauryl phosphate, sodium
laureth-4-phosphate, dilaureth-4-phosphate, sodium oleyl phosphate,
sodium laureth-4-sulfosuccinate and the like. Additional compounds
that may be suitable for use as the stabilizer component are
described in U.S. Pat. No. 5,873,931, issued Feb. 23, 1999.
[0022] The surfactant composition may be in solution or emulsion or
provided as a dry coating on a substrate. When in solution or
emulsion, the surfactant composition can be dissolved in any
suitable solvent. Suitable solvents include water and organic
solvents such as, but not limited to, ketones, ethers, and
alcohols. Suitable alcohols include methanol, ethanol, 1-propanol,
2-propanol, and butanol. In certain embodiments, a suitable solvent
may include a hydroalcoholic solvent such as a 70/30 mix of
isopropyl alcohol and water. The surfactant composition also may be
provided as a dispersion or emulsion in a suitable vehicle. For
certain applications, the vehicle may contain water in order to
provide a more uniform coating.
[0023] In one embodiment of the present invention, the surfactant
composition includes a solution of from about 0.05% to about 0.5%
stabilizer component and from about 0.1% to about 0.6% surfactant
component. Therefore, when applied to a substrate and dried the
composition comprises a surfactant and stabilizer in a ratio of
surfactant to stabilizer of 0.2:1 to 12:1 wt/wt. Once dried, the
concentration of the surfactant component is 25-95% by weight on a
solvent-free basis in the dried coating, and the stabilizer
component is 5-75% by weight on a solvent-free basis in the dried
coating. In many embodiments, the concentration of the surfactant
component is 40-80% by weight on a solvent-free basis in the dried
coating, and the stabilizer component is 20-60% by weight on a
solvent-free basis in the dried coating. As used herein,
"solvent-free basis" means the dried coating free of any solvent,
excluding water or other volatile absorbed by the coating on
exposure to air or external conditions.
[0024] As indicated above, certain embodiments may include sodium
dodecylbenzene sulfonate as the stabilizer component. Also, as
indicated above, certain embodiments may include one or more of a
wide variety of surfactants in the surfactant component. The
surfactant component in particular embodiments in neat form at
temperatures below 45.degree. C. and preferably at temperatures
below 25.degree. C., is a liquid and includes one or more
ethoxylated diols, polyethoxylated phenols or aralkyl sulfonates in
the surfactant composition. In one embodiment, the surfactant
component includes an ethoxylated acetylenic diol. The ethoxylated
diol contains one or more moles of ethylene oxide per mole of
acetylenic diol, and preferably 4 or more moles of ethylene oxide
per mole of acetylenic diol.
[0025] In another aspect, the present invention provides a
surfactant composition that dries to form a dry surfactant coating
that imparts hydrophilic character to a surface or substrate coated
with the surfactant composition. The surfactant composition may be
deposited on any surface for which the features of the surfactant
composition of the present invention may be desirable. For example,
the surfactant composition may be deposited on at least a portion
of a surface designed to regulate movement of a liquid sample.
Examples of such devices include, but are not limited to, devices
useful for performing diagnostic or detection tests on a liquid
sample. It may be desirable for such devices to have a surface that
is hydrophilic to promote transport of at least a portion of a
liquid sample from one location on the device to another location.
However, the surface of the device over or through which the sample
must travel ordinarily may not be sufficiently hydrophilic to
provide adequate performance of the device. In such a case, the
surfactant compositions of the present invention may be deposited
on at least a portion of the fluid transport surface in order to
promote fluid transport of the liquid sample sufficient to provide
adequate performance of the device. It could also be deposited in
various patterns to control fluid flow in specific manner such as
continuous, discontinuous, or repeating patterns.
[0026] The surfactant composition, in the solution form described
above, may be deposited on at least a portion of the surface for
which the surfactant coating is desired. The surfactant solution
may be deposited by any suitable method known in the art. Such
methods include, but are not limited to, spray coating, roller
coating, gravure coating, wire-bar coating, dip or immersion
coating, extrusion (die) coating, air knife coating, slide coating,
blade coating, electrostatic coating, ink jet printing, or flow
coating.
[0027] The surfactant composition may also be incorporated into a
substrate allowing a portion of the composition to bloom to the
surface. This can be done in cast and cure systems such as acrylic
substrates where the surfactant and stabilizer components are added
to the uncured or partially cured monomers and the substrate is
finally cured. Alternatively, the surfactant composition can be
added to a thermoplastic during the extrusion or injection molding
process.
[0028] The surfactant solution may be dried, thereby forming a
substantially dry hydrophilic surfactant coating by any suitable
means. As used herein the terms "dried" or "drying" refer to the
process of removing the solvent in which the surfactant composition
is dissolved or emulsified which may or may not include water. For
example, the surfactant solution can be dried by heating the coated
substrate in a recirculating hot air oven, an infrared oven, or a
radio frequency oven. Alternatively, the solution can be dried
without heat by simple evaporation or forced air evaporation. The
temperature and duration of the heating can be determined, in part,
by the physical and chemical composition of the substrate, i.e.,
some substrate materials may be able to withstand higher
temperatures without alteration of certain physical or chemical
properties that may be desired for the substrate after the coating
process is complete. Other substrates may have embossed or other
microreplicated structures that may require higher or lower thermal
profiles to dry the coating uniformly.
[0029] The substrate may be constructed of any material that can be
coated and, in practice, may be dictated, at least in part, by the
physical and structural requirements of the intended application.
Suitable substrates include, but are not limited to, glass, metal,
and polymeric substrates of various construction and composition,
including plates, mesh films, nonwovens, tubes, capillaries, flat
or structured films, and film/film or film/non-woven laminates. In
most embodiments, the substrates are non-porous. Most preferred
substrates are films which may or may not comprise three
dimensional structures such as channels, pyramids, pockets and the
like. Examples of suitable polymeric compositions and
configurations of substrates that can be coated by the surfactant
compositions of the present invention are described, for example,
in U.S. Pat. No. 5,514,120, issued May 7, 1996; U.S. Pat. No.
5,728,446, issued Mar. 17, 1998; U.S. Pat. No. 6,290,685, issued
Sep. 18, 2001; U.S. Pat. No. 6,375,871, issued Apr. 23, 2002; U.S.
Pat. No. 6,420,622, issued Jul. 16, 2002; and U.S. Pat. No.
7,223,364, issued May 29, 2007. Substrate configurations reported
therein may be suitable regardless of the specific materials used
to construct the substrate. Polymeric substrates may be formed by
any suitable means including extrusion, injection molding, blow
molding, compression molding, casting, and the like.
[0030] The substrate may determine, in part, solvents that are
deemed suitable for use in depositing the surfactant composition
onto at least a portion of the substrate. Certain plastic
substrates can craze crack, weaken or dissolve if contacted with
incompatible solvents. For example, polycarbonate substrates can be
affected, sometimes severely, by exposure to ketone solvents such
as acetone. However, such substrates can be coated with surfactant
compositions dissolved in alcohol-based solvents without
detrimental effects.
[0031] The dry surfactant coating may be of any thickness desired
for a particular purpose. For example, the dry surfactant coating
can be from about 10 nm to about 2000 nm thick. In some
embodiments, the dry coating can be from about 60 nm to about 300
nm thick. The thickness of the coating may be selected based on the
nature of the substrate and may depend, in part, on any
requirements for coating uniformity. For substrates that contain
microfine features, thinner coatings ranging from about 10 nm to
about 1000 nm may be suitable to reduce the likelihood and extent
of filling in such microfine features. In certain embodiments,
coatings ranging from about 50 nm to about 500 nm may be used in
connection with substrates having microfine structures.
[0032] The coating solution generally includes less than about 5%
by weight stabilizer component and less than about 5% by weight
surfactant component. It may become difficult to obtain a uniform
coating if the concentration of one or both components is too high.
In order to provide a uniform coating, the stabilizer concentration
can be less than about 2%, by weight, of the total surfactant
composition. Certain surfactant compositions of the present
invention include less than 1%, by weight, stabilizer component,
e.g., about 0.05% to about 0.5%.
[0033] The surfactant component also may be kept at relatively low
concentration in order to provide a uniform coating. The surfactant
component concentration may be less than about 2% by weight of the
total surfactant composition. Certain surfactant compositions may
include less than about 1% by weight surfactant component, e.g.,
from about 0.1% to about 0.6%.
[0034] As described above, the surfactant compositions of the
present invention provide a hydrophilic coating to the surface or
substrate to which it has been applied. Such hydrophilic character
may provide the coated surface with certain functional capabilities
that may be desirable for a particular application. For example, if
the surfactant coating is applied to the surface of a fluid
transport control film of a diagnostic device, the surfactant
coating may improve the rate or extent to which the fluid control
film is able to receive a liquid sample. The surfactant coating
also can improve the speed, uniformity and consistency of the flow
of the liquid sample from a fluid receiving portion of the fluid
control film to a diagnostic or analytical portion of the fluid
control film. The surfactant compositions of the present invention
also can provide a hydrophilic coating that retains its hydrophilic
character and at the same time provides a surface that allows for
good adhesion to wide range of adhesives, including pressure
sensitive adhesives such as acrylic and block copolymer adhesives
such as KRATON based adhesives. A simple check for good adhesion is
performed by adhering double-sided tape (Product no. 315, available
from 3M, St. Paul, Minn.) to the film, adhering this to a second
substrate such as glass, aging at 23C and 50% relative humidity for
7 days and checking for adhesion. The preferred samples of the
present invention remain adhered for longer than 21 weeks.
[0035] The surfactant compositions of the present invention also
can provide a hydrophilic coating that retains its hydrophilic
character longer than alternative hydrophilic coatings, even at
elevated temperatures. Thus, a surface coated with the disclosed
surfactant composition may provide the benefits associated with the
hydrophilic coating for a longer period of time and/or at a higher
temperature than a similar surface coated with an alternative
hydrophilic coating. A device that includes a surface coated with
the surfactant composition may therefore have a longer useful life
than a similar device that includes a surface coated with an
alternative hydrophilic coating, thereby providing a device that
may be more likely to be used before its useful life is exhausted,
and reducing waste generated by the discarding of expired
devices.
[0036] For example, a substrate coated with a non-stabilized
hydrophilic surfactant composition can lose a substantial portion
of its hydrophilic character if stored, for example, for 30 days at
45.degree. C. and a relative humidity of 50% in an indoor
environment. One measure of hydrophilicity is the time required for
a portion of a liquid sample to move from one point on the coated
surface to another point on the coated surface, defined
interchangeably as wicking rate or fill time. Shorter liquid
transport times correlate with greater hydrophilic character of the
surface. Non-stabilized hydrophilic surfactants may experience a
significant decrease in fill time, i.e., greater than 15%, after
being stored, for example, for three weeks at 40.degree. C. In
contrast, a substrate coated with a stabilized surfactant
composition according to the present invention can experience
decrease in fill time, i.e., less than 85%, after storage for a
similar period under similar conditions.
[0037] Another measure of hydrophilicity is the contact angle
measurements of a surface over time which can be used to monitor
the changes in surface wetting characteristics of coated
substrates. Lower contact angle values correlate with greater
hydrophilic character of the surface. Non-stabilized hydrophilic
surfactants may experience a significant change in contact angle
after being stored, for example, for thirteen weeks at 25.degree.
C. In contrast, a substrate coated with a stabilized surfactant
composition according to the present invention can experience
little or no change in contact angle value after storage for a
similar period under similar conditions.
[0038] The surfactant compositions of the present invention also
can provide coatings that are compatible with a wide variety of
applications. For example, many of the surfactant compositions of
the present inventions may be useful for coating fluid control
surfaces of diagnostic or detection devices because they may be
non-reactive with reagents or sample components involved in the
diagnostic or detection analysis. Thus, hydrophilic coatings of
surfactant compositions of the present invention may be selected so
that they do not interfere with the chemical or physical
environmental requirements of the diagnostic or detection assay.
Non-ionic surfactants and anionic stabilizers of the present
invention are particular compatible with reagents in test strips
such as glucose test strips, such as those disclosed in U.S. Pat.
No. 6,270,637.
[0039] Certain surfactant compositions of the present invention can
provide hydrophilic coatings that retain a certain level of clarity
over the storage period. Thus, when used in devices in which
clarity of the hydrophilic coating is desired, such surfactant
compositions can have particular utility. This is particularly
important when coated on transparent substrates such as
polyethylene terephthalate, polycarbonate, acrylics and the
like.
[0040] Accordingly, certain embodiments of the present invention
may be particularly useful for providing hydrophilic coatings on
fluid transport surfaces of, for example, a diagnostic device,
because the disclosed surfactant compositions provide a coating
that is 1) hydrophilic so that the coating promotes efficient
transport of at least a portion of a liquid sample from a sample
receiving portion of the device to an analytical portion of the
device; 2) stable so that the hydrophilic character and, in some
cases, the clarity of the surface is maintained, thereby increasing
the likelihood that the device will be used before its useful life
is exhausted; 3) non-reactive with both the reagents and the sample
components involved in the diagnostic assay; and 4) provides a
surface that has good adhesion properties to a variety of
conventional adhesives used for such devices. Each of these
features of the surfactant composition contribute to improving the
performance of a device that includes a surface coated with a
surfactant composition according to the present invention.
[0041] The invention is further illustrated by the following
examples, which are not intended to limit the scope of the
invention. In the examples, parts, ratios and percentages are by
weight unless otherwise indicated.
EXAMPLES
GLOSSARY
TABLE-US-00001 [0042] Chemical Acronym Trade Name Description
Source/Address Reagent 1 Roche Diagnostics/ Indianapolis, IN
Reagent 2 Roche Diagnostics DYNOL 604 ethoxylated Air Products and
acetylenic diol Chemicals, Inc., Allentown, PA. SURYNOL 465
ethoxylated Air Products and acetylenic diols Chemicals, Inc. TAGAT
L2 Polyoxyethylene Degussa- glycerol Goldschmidt/ monolaurate
Hopewell, VA LAMBENT 703 silicone copolyol Lambent Technologies/
Fernandina Beach, FL ZONYL FSN Fluorochemical E. I. Du Pont De
surfactants - Nemours & Co./ nonionic (40% Wilmington, DE
solids) POLYSTEP A16 Sodium branched Stepan Company/ alkyl benzene
Northfield, IL sulfonate AEROSOL OT Dioctyl ester of Cytec
Industries/ sodium West Patterson, NJ sulfosuccinic acid FC95
FLUORAD 95 Potassium 3M Company/St. perfluoroalkyl Paul, MN
sulfonates - anionic (100%)
Examples 1-2
[0043] A coating solution was prepared by adding a surfactant
component and a stabilizer component in the amounts shown in Table
1a to a 70/30 weight percent isopropyl alcohol (IPA)/water
solvent.
TABLE-US-00002 TABLE 1a Composition of Coating Solutions Solvent
Coating IPA/Water Surfactant Stabilizer Composition 70/30 DYNOL 604
RHODACAL DS10 No. (wt. %) (weight percent) (weight percent) 1 99.2
0.6 0.2
[0044] Preparation of Coated Substrate: Composition 1 was coated
onto a polyester plastic film (commercially available as MELINEX
454 from E.I. duPont de Nemours and Company, Wilmington, Del.)
using the reverse Gravure roll method with knurled roll (Tool
reference #34, cell count of 150, Parmarco Inc., Batavia, Ill.)
with a pitch of 150 (volume factor of 0.89). The roll to line speed
ratio was maintained at 2:1 or 1.5:1. After coating, the solution
was dried in an oven (10 foot Air Flow oven, part of Hirano Coater,
Hirano Co., Japan) at 75.degree. C. The uniformity of the coating
was checked visually when the coating was still wet and then by
applying a drop of water every 1/2 inch to 1 inch across the web
and noticing the diameter and wicking characteristics of the drop.
The thickness of the dry coating was determined using a Scanning
Electron Microscopy (Hitachi model S-4500 field emission SEM
(FESEM)). The thickness of the dry coating varied from 60 nm to 200
nm.
[0045] Examples 1 and 2 were prepared by combining the coated
substrate with the chemistry of Reagent 1 and Reagent 2
respectively, such as those reagents disclosed in U.S. Pat. No.
6,270,637. The coated substrate was the foil used to make the
"capillary roof" of prototype Blood glucose (bG) test strips that
function in a manner similar to those described in U.S. Pat. No.
6,270,637 for Examples 1-2.
Fill Time Test: Roche Diagnostics Corp. (Indianapolis, Ind.) tested
the test strips using the following procedure: One tube of whole
blood was drawn the day of testing using lithium heparin as an
anticoagulant and a hematocrit corresponding to 42%.+-.2%.
[0046] Several electronic components was used to record and time
the image of blood sample as it filled the capillary chamber of the
sensor: Casablanca video editing system with a removable hard
drive, Sony TRINITRON monitor, HORITA time stamp generator,
PANASONIC Digital 5000 video Camera, MITSUBISHI VCR, and a DYNA
Fiber Optic Light.
[0047] The removable hard drive was placed into the Video Editing
System and the electronic components listed above were turned on.
The `display` key was pressed to start the timer. A strip from the
ACCU-CHEK Advantage meter was placed under the camera. The `edit`
button was selected from the main menu on the video editing system.
Next, the `record` button was selected and the image from the
camera appeared. The lighting was adjusted by turning the
adjustment knob on the fiber optic light source. The image of the
sensor was focused using the macro ring and lens on the video
camera. The time stamp was checked for format (typically SS:TH) and
to determine that it was running. Using a RAININ pipette for the
appropriate sample volume (2.0 .mu.L for NWS-V type sensors, 1.0
.mu.L for Crusader type sensors), this volume was withdrawn from
the tube of mixed whole blood. The tip of the pipette was wiped
using a KIMWIPE and the plunger depressed to form a hanging drop.
The video editing system was started by selecting the `record`
button with the left mouse button. The sensor was immediately dosed
by touching the blood drop to the middle of a sensor portion of the
test strip. The `stop` button was pressed with the left mouse
button. Each clip was labeled automatically by the video editing
system with an ID starting with the letter S and followed by
incremental numbers indicating the slide number. A log sheet was
used to record sample volume, hematocrit, and sensor ID. The
process was repeated until all of the sensors were filled and
recorded.
[0048] After all of the sensors were recorded, the first recorded
slide was selected and the `trim` button was selected on the `edit`
screen of the video editing system. Using the roller ball, `in` was
selected; the ball was rolled to the right until the first instant
that the blood sample entered the capillary chamber. The time
displayed on the screen by the time stamp generator was recorded as
the `initial` time in seconds.
[0049] The ball was rolled to the right again until the blood
sample reached the drop detect electrodes. This was the first
moment that the blood sample bridges the vertical gap between the 2
drop detect electrodes so the blood was touching both electrodes.
The time displayed on the screen was recorded as the `sample
sufficiency` time.
[0050] The `total fill time` was calculated by subtracting the
`initial time` from the `sample sufficiency` time.
[0051] Test strips were aged for 0 weeks (T.sub.0), 3 weeks
(T.sub.3), 6 weeks (T.sub.6), 13 weeks (T.sub.13) and 21 weeks
(T.sub.21) at three different temperatures (4.degree. C.,
32.degree. C., and 45.degree. C.) in storage vials. The results of
total fill time at 4.degree. C., 32.degree. C. and 45.degree. C.
after aging for T.sub.13 and T.sub.21 are shown in Table 1b.
TABLE-US-00003 TABLE 1b Results of Fill Time Test at T.sub.13, and
T.sub.21 and at 4.degree. C., 32.degree. C. and 45.degree. C. Total
Fill Time (seconds) At 4.degree. C. At 32.degree. C. At 45.degree.
C. Example No. T.sub.13 T.sub.21 T.sub.13 T.sub.21 T.sub.13
T.sub.21 1 0.18 0.20 0.29 0.29 0.20 0.22 2 0.31 0.20 0.16 0.17 0.50
0.34
[0052] The results indicated that a combination of the DYNOL 604
ethoxylated acetylenic diol and the RHODACAL DS 10 was very stable.
The fill time of Example 1 remained the same or decreased after 1
week of aging at each temperature tested.
Water Contact Angle Measurements: Water Contact Angle Measurements
were used to monitor the changes in surface wetting characteristics
of coated films. These films were cut into 8 by 70 mm strips,
stored at 25.degree. C., 32.degree. C., and 45.degree. C. for 0, 1,
3, 6, 9, 13, 21, 26, 39, 52, 78, and 104 weeks in storage vials
(Glass with screw cap tops containing TEFLON-coated liners
(TEFLON-coated side of liner was always oriented towards inside of
jar.), 40 mL (I-Chem/VWR#IRC236-0040)), and subjected to water
contact angle measurements. Water (Type I) contact angles were
determined using video contact angle analyses (commercially
available as First Ten Angstroms, model FTA 125 Video Contact Angle
Analysis System). For each combination of storage temperature/time,
three strips were measured for contact angle on the hydrophilic
interface between the liner and the film.
[0053] Disposable nitrile gloves were used to handle the test
strips and the surfaces were not touched prior to or during
testing.
[0054] FTA analysis: The 100-.mu.L instrument syringe was filled
with Type I water. The lighting, camera focus and aperture were
adjusted for the best image at the syringe needle tip. The strip
was placed on the metal plate located on top of the FTA sample
stage. The ends of the strip were secured with magnets with the
edge of the test strip as close to the edge of the metal plate as
possible. If the test strip was lying flat with no wrinkles, the
FTA sample stage was oriented so that the camera optical path was
perpendicular to the front edge of the test strip. The stage was
moved until the syringe needle was just inside the strip edge so
that there was enough room to dispense a water drop. A video movie
(about 4 seconds) was collected for analysis for each contact
angle. The purpose was to capture a movie that framed time zero and
a progression of images until drop equilibration was
established.
[0055] The test strip was lying flat without any wrinkles, and a
piece of double-sided tape (Product no. 315, available from 3M, St.
Paul, Minn.) was affixed along the lengthwise edge of a 25 by 75 mm
glass slide. The strip to be tested was attached to the tape on the
slide with the edge of the test strip as close to the edge of the
slide and tape as possible. The slide with the attached test strip
on the metal plate located on top of the FTA sample stage and the
video movie was made as previously described.
[0056] Initial and `at equilibrium` contact angles were recorded
for each analysis area. The average of nine water contact angles
were calculated and recorded in degrees for each strip. The results
of Average Water Contact Angle Measurements at 25.degree. C.,
32.degree. C. and 45.degree. C. after 13 and 21 weeks for Examples
1 and 2 are shown in Table 1c.
TABLE-US-00004 TABLE 1c Water Contact Angle Measurements of Test
Strip Surface at T.sub.13, and T.sub.21 and at 25.degree. C.,
32.degree. C. and 45.degree. C. Initial Contact Angle/Final Contact
Angle (degrees) At 25.degree. C. At 32.degree. C. At 45.degree. C.
Example No. T.sub.13 T.sub.21 T.sub.13 T.sub.21 T.sub.13 T.sub.21 1
19/10 16/10 14/10 16/10 16/10 18/10 2 14/10 14/10 15/10 15/10 17/10
14/10
[0057] The smaller contact angle values for Example 1 and 2
indicate that the surface is very hydrophilic through a range of
temperatures, including elevated temperatures, and remains
hydrophilically stable over a significant period of time, i.e.,
twenty-one weeks.
Example 3
[0058] The coating solution, the preparation of the coated
substrate and the construction of the test strip was the same as
that described for Examples 1 and 2.
[0059] The test strips were evaluated for fill time using the Fill
Time Test described for Examples 1 and 2. The results of total fill
time at 4.degree. C., 32.degree. C. and 45.degree. C. after aging
for T.sub.13 and T.sub.21 are shown in Table 2a.
TABLE-US-00005 TABLE 2a Results of Fill Time Test at T.sub.0,
T.sub.3, T.sub.6, T.sub.13, and T.sub.21 and at 4.degree. C. Total
Fill Time (seconds) T.sub.0 T.sub.3 T.sub.6 T.sub.13 T.sub.21
Example No. At 25.degree. C. At 4.degree. C. At 4.degree. C. At
4.degree. C. At 4.degree. C. 3 0.14 .+-. 0.03 0.42 .+-. 0.27 0.27
.+-. 0.22 0.31 .+-. 0.25 0.20 .+-. 0.16
TABLE-US-00006 TABLE 2b Results of Fill Time Test at T.sub.0,
T.sub.3, T.sub.6, T.sub.13, and T.sub.21 and at 32.degree. C. Total
Fill Time (seconds) T.sub.0 T.sub.3 T.sub.6 T.sub.13 T.sub.21
Example No. At 25.degree. C. At 32.degree. C. At 32.degree. C. At
32.degree. C. At 32.degree. C. 3 0.14 .+-. 0.03 0.49 .+-. 0.28 0.35
.+-. 0.18 0.16 .+-. 0.03 0.17 .+-. 0.08
TABLE-US-00007 TABLE 2c Results of Fill Time Test atT.sub.0,
T.sub.3, T.sub.6, T.sub.13, and T.sub.21 and at 45.degree. C. Total
Fill Time (seconds) T.sub.0 T.sub.3 T.sub.6 T.sub.13 T.sub.21
Example No. At 25.degree. C. At 45.degree. C. At 45.degree. C. At
45.degree. C. At 45.degree. C. 3 0.14 .+-. 0.03 0.52 .+-. 0.14 0.23
.+-. 0.06 0.50 .+-. 0.37 0.34 .+-. 0.23
[0060] The fill time of Example 3 increased slightly after 3 to 6
weeks of aging at each temperature tested and decreased to nearly
the same time after 13 to 21 weeks of aging.
[0061] The hydrophilic films were evaluated using the Water Contact
Angle Measurements described in Examples 1 and 2. The results are
shown in Table 2d, 2e, and 2f.
TABLE-US-00008 TABLE 2d Water Contact Angle Measurements of Test
Strip Surface at T.sub.0, T.sub.1, T.sub.3, T.sub.6, T.sub.9,
T.sub.13, T.sub.21, T.sub.26 and at 25.degree. C. Initial Contact
Angle/Final Contact Angle (degrees) Example At 25.degree. C. No.
T.sub.0 T.sub.1 T.sub.3 T.sub.6 T.sub.9 T.sub.13 T.sub.21 T.sub.26
3 22/<10 25/<10 20/<10 22/<10 21/<10 21/<10 22/10
22/<10
TABLE-US-00009 TABLE 2e Water Contact Angle Measurements of Test
Strip Surface at T.sub.0, T.sub.1, T.sub.3, T.sub.6, T.sub.9,
T.sub.13, T.sub.21, T.sub.26 and at 32.degree. C. Initial Contact
Angle/Final Contact Angle (degrees) Example At 32.degree. C. No.
T.sub.0 T.sub.1 T.sub.3 T.sub.6 T.sub.9 T.sub.13 T.sub.21 T.sub.26
3 NA* 23/<10 19/<10 21/<10 20/<10 20/<10 23/10
21/<10 *Not available
TABLE-US-00010 TABLE 2f Water Contact Angle Measurements of Test
Strip Surface at T.sub.0, T.sub.1, T.sub.3, T.sub.6, T.sub.9,
T.sub.13, T.sub.21, T.sub.26 and at 45.degree. C. Initial Contact
Angle/Final Contact Angle (degrees) Example At 45.degree. C. No.
T.sub.0 T.sub.1 T.sub.3 T.sub.6 T.sub.9 T.sub.13 T.sub.21 T.sub.26
3 NA* 23/<10 21/<10 21/<10 20/<10 19/<10 22/10
20/<10 *Not available
[0062] For comparison purposes, the water contact angle of the back
of the test strip (without hydrophilic coating) measured 43/24
Initial/Final in degrees at To and was 91/91 Initial/Final in
degrees after 26 weeks of aging at 45.degree. C. In contrast, the
contact angle of Example 3 was initially lower than the comparison
value, and remained low through 26 weeks of aging.
Examples 4-13 and Comparative Examples A-I
[0063] Coating solutions were prepared by adding the amounts of the
components given in Table 3a to a 70/30 weight percent IPA/water
solvent.
TABLE-US-00011 TABLE 3a Solvent Surfactants Stablilizers Example
IPA/water Amount Amount Number (wt. %) Type (wt. %) Type (wt. %) 4
99.60 DYNOL 604 0.30 POLYSTEP 0.10 A16 5 99.60 SURFYNOL 0.30
POLYSTEP 0.10 465 A16 6 99.60 TAGAT L2 0.30 POLYSTEP 0.10 A16 7
99.60 LAMBENT 0.30 POLYSTEP 0.10 703 A16 8 99.15 ZONYL FSN 0.75
POLYSTEP 0.10 (40%) A16 9 99.60 DYNOL 604 0.30 AEROSOL 0.13 OT
(75%) 10 99.60 DYNOL 604 0.30 FC95 0.10 11 99.57 LAMBENT 0.30
AEROSOL 0.13 703 OT (75%) 12 99.60 LAMBENT 0.30 FC95 0.10 703 13
99.12 ZONYL FSN 0.75 AEROSOL 0.13 (40%) OT (75%) Compara- 99.15
ZONYL FSN 0.75 FC95 0.10 tive A (40%) Compara- 99.70 DYNOL 604 0.30
None 0.00 tive B Compara- 99.70 SURFYNOL 0.30 None 0.00 tive C 465
Compara- 99.70 TAGAT L2 0.30 None 0.00 tive D Compara- 99.70
LAMBENT 0.30 None 0.00 tive E 703 Compara- 99.75 ZONYL FSN 0.75
None 0.00 tive F Compara- 99.87 None 0.00 AEROSOL 0.13 tive G OT
Compara- 99.90 None 0.00 POLYSTEP 0.10 tive H A16 Compara- 99.90
None 0.00 FC95 0.10 tive I
[0064] The solutions were coated onto a polyester plastic film
(0.10 mm thick biaxially oriented corona discharge treated
polyethylene terephalate film) using a Meyer rod and the coating
was dried at 100.degree. C. The coated films were subjected to
accelerated aging (which was used for the data in Table 2b). Coated
films were cut to approximately 7.5.times.12 cm pieces and placed
vertically in a rack and all surfaces were exposed to recirculating
air in a constant temperature (25.degree. C.) and relative humidity
(50%) room. The hydrophilicity was evaluated every week to 21 days
using the Spreading Drop Test.
[0065] Spreading Drop Test: Each film sample was conditioned at
23.degree. C. and 50 percent relative humidity for a minimum of 8
hours before and during testing. Care was taken to ensure that the
film samples were not contaminated and that exposure to the
environment did not result in decreased wetting. The film samples
were placed on a clean flat horizontal surface with the side to be
tested up. At ambient conditions (approximately 23.degree. C.) a 3
microliter drop of deionized and distilled water containing 0.07%
by weight "Wool Fast Brilliant Red R.L. Dye," commercially
available from Pylam, Garden City, N.Y., from an accurate syringe
was gently placed on the surface by holding the syringe vertically
and just touching the drop to the surface so that the drop did not
fall and impact the surface. The drop was allowed to spread to its
maximum extent and completely dry. The diameter of the drop was
determined by placing the film over a paper with premeasured
circles of varying diameters. The average drop diameter was
recorded. Irregular shaped drop sizes were approximated. The
percent retention of the drop size was calculated between day 7 and
day 22. Table 3b shows percent retention of the drop size or the
hydrophilic properties.
TABLE-US-00012 TABLE 3b Spreading Drop Diameter (cm) Percent
Example After 7 After 14 After 22 After 29 Retention Number days
days days days (%) 4 7.1 7.5 7.2 6.9 101.4 5 6.6 6.2 7.3 7.0 110.6
6 7.4 6.9 6.7 6.9 90.9 7 8.1 7.3 7.4 7.3 91.5 8 7.0 7.0 7.3 6.9
104.8 9 8.7 7.8 7.5 7.1 86.9 10 7.6 6.8 6.8 6.9 89.5 11 7.8 7.9 7.3
7.5 93.2 12 8.4 8.0 8.1 8.0 96.0 13 7.3 6.8 6.6 7.8 89.8
Comparative A 7.2 6.7 5.9 7.0 81.9 Comparative B 12.0 9.0 9.5 9.2
79.0 Comparative C 7.6 6.8 6.1 6.7 80.3 Comparative D 6.7 6.3 5.5
6.3 82.1 Comparative E 8.0 6.8 6.8 7.2 84.9 Comparative F 6.8 6.2
5.7 6.4 83.8 Comparative G 8.1 7.7 6.6 7.2 81.6 Comparative H 8.3
6.9 6.3 6.9 76.0 Comparative I 7.1 5.6 5.6 6.4 78.9
[0066] The results of the spreading drop test for Examples 4-13
were greater than 87 percent retention while the results of the
spreading drop test for Comparative Examples A-I were less than 85
percent retention.
[0067] Various modifications and alterations to this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. The complete disclosures of
the patents, patent documents and publications cited herein are
incorporated by reference in their entirety as if each were
individually incorporated. In case of conflict, the present
specification, including definitions, will control.
[0068] It should be understood that this invention is not intended
to be unduly limited by the illustrative embodiments set forth
herein and that such illustrative embodiments are presented by way
of example only with the scope of the invention intended to be
limited only by the claims set forth herein as follows.
* * * * *