U.S. patent application number 09/954729 was filed with the patent office on 2002-03-28 for method of making a colored reflective article that has a dye covalently bonded to a polymer.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Fleming, Robert J..
Application Number | 20020037364 09/954729 |
Document ID | / |
Family ID | 23310130 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020037364 |
Kind Code |
A1 |
Fleming, Robert J. |
March 28, 2002 |
Method of making a colored reflective article that has a dye
covalently bonded to a polymer
Abstract
Exposed lens retroreflective article 10 that comprises a colored
layer 14 and a layer of optical elements 12 that are partially
embedded in the colored layer 14. The colored layer 14 comprises
reflective flakes 16 and a dye that is covalently bonded to a
polymer 18. The articles can retain their color after multiple
industrial wash cycles. The use of a reactive dye, reflective
flakes, and/or polymer precursor during the preparation of the
colored layer enables a launderably-durable colored retroreflective
article to be made without the use of a solvent and without the use
of a temporary carrier.
Inventors: |
Fleming, Robert J.; (Lake
Elmo, MN) |
Correspondence
Address: |
Office of Intellectual Property Counsel
3M Innovative Properties Company
P.O. Box 33427
St. Paul
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
23310130 |
Appl. No.: |
09/954729 |
Filed: |
September 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09954729 |
Sep 18, 2001 |
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09453321 |
Dec 2, 1999 |
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6306459 |
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09453321 |
Dec 2, 1999 |
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09335068 |
Jun 17, 1999 |
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Current U.S.
Class: |
427/162 |
Current CPC
Class: |
A41D 31/325 20190201;
G02B 5/128 20130101; A41D 13/01 20130101 |
Class at
Publication: |
427/162 |
International
Class: |
B05D 005/06 |
Claims
What is claimed:
1. An exposed lens retroreflective article that comprises: a
colored layer that comprises reflective flakes disposed in a
polymeric material, the polymeric material comprising a dye that is
covalently bonded to a polymer; and a layer of optical elements
that are partially embedded in the colored layer.
2. The exposed lens retroreflective article of claim 1, wherein the
optical elements are light transmissive microspheres.
3. The exposed lens retroreflective article of claim 2, wherein the
colored layer comprises 10 to 50 weight % reflective flakes based
on the weight of the colored layer.
4. The exposed lens retroreflective article of claim 3, wherein the
colored layer further comprises a coupling agent that improves
adhesion of the colored layer to the microspheres.
5. The exposed lens retroreflective article of claim 4, wherein the
colored layer consists essentially of polymer, dye, reflective
flakes, and coupling agent.
6. The exposed lens retroreflective article of claim 3, wherein the
polymer comprises a polyurethane or a polyacrylate.
7. The exposed lens retroreflective article of claim 1, wherein the
colored layer comprises a polymer made from a monomeric unit
selected from the group consisting of urethane, ester, ether, urea,
epoxy, carbonate, acrylate, acrylic, olefin, vinyl chloride, amide,
alxyd, and combinations thereof.
8. The exposed lens retroreflective article of claim 7, wherein the
colored layer has an average thickness of about 50 to 300
micrometers.
9. The exposed lens retroreflective article of claim 1, wherein
neither the x or y color coordinates on the standard CIE 1931
chromaticity diagram change by no more than 0.02 after 20 cycles of
the Industrial Laundering Procedure 1.
10. The exposed lens retroreflective article of claim 1, wherein
neither the x or y color coordinates on the standard CIE 1931
chromaticity diagram change by more no than 0.02 after 20 cycles of
the Industrial Laundering Procedure 2.
11. The exposed lens retroreflective article of claim 2, wherein E*
changes by 4 or less after 20 wash cycles of the Industrial
Laundering Procedure 1.
12. The exposed lens retroreflective article of claim 2, wherein E*
changes by 4 or less after 20 wash cycles of the Industrial
Laundering Procedure 2.
13. The exposed lens retroreflective article of claim 1, wherein
the colored layer comprises ester urethane units and a
hydroxyl-functionalized reactive dye.
14. An article of clothing that has the exposed lens
retroreflective article of claim 1 secured to an outer surface
thereof.
15. The article of clothing of claim 14 being a firefighter's
jacket or a safety vest.
16. A transfer article that comprises the article of claim 2, and a
carrier web into which the layer of microspheres is also partially
embedded.
17. A method of making a colored retroreflective article, which
method comprises: contacting a precursor color coating with optical
elements, wherein the precursor color coating comprises a reactive
dye, reflective flakes, and a polymer precursor; and curing the
precursor color coating to form a colored layer that contains the
reflective flakes, that has the dye covalently bonded to a polymer,
and that has the optical elements supported by the colored
layer.
18. The method of claim 17, wherein the precursor color coating
does not contain solvent.
19. The method of claim 18, wherein the precursor color coating
comprises 0.5 to 20 weight percent of a reactive dye and 20 to 40
weight percent of reflective flakes.
20. The method of claim 18, wherein the precursor color coating
comprises a polyether polyol, an organic polyisocyanate, and a
poly-hydroxyl-functionalized dye.
21. The method of claim 20, wherein the precursor color coating
further comprises a silane coupling agent.
22. The method of claim 18, wherein the precursor color coating
comprises an acrylate monomer, a polyol, and an isocyanate.
23. The method of claim 18, wherein the precursor color coating is
applied to release paper, and then the optical elements are applied
over the precursor color coating, wherein the optical elements are
not disposed in a carrier layer.
24. A solventless method of making a retroreflective article, which
method comprises: applying a solventless precursor color coating
layer on the surface of a substrate, wherein the precursor color
coating layer comprises a dye, reflective flakes, and a polymer
precursor; applying optical elements onto the precursor color
coating layer, wherein the optical elements are not disposed in a
carrier layer; and curing the precursor color coating to form a
colored layer.
25. The method of claim 24, wherein the optical elements are light
transmissive microspheres.
26. The method of claim 24, wherein the dye is a reactive dye.
27. The method of claim 24, wherein the microspheres are spread out
over the surface of the precursor color coating.
28. The method of claim 24, wherein the polymer precursor comprises
an actylate monomer, a polyol, and an isocyanate.
Description
[0001] The present invention pertains to a retroreflective article
that includes a colored layer that contains reflective flakes and a
dye. The dye is covalently bonded to a polymer.
BACKGROUND
[0002] Persons who work or exercise near motor vehicle traffic can
be made safer by wearing clothing that highlights the person's
presence to passing motor vehicles. To promote the safety of
roadway workers and pedestrians, clothing manufacturers commonly
produce bright clothing to make the wearer more conspicuous.
Manufacturers also regularly secure retroreflective articles to the
outer surface of the clothing to improve wearer conspicuity.
Retroreflective articles are passive devices that return incident
light back toward the light source. The articles highlight a
person's presence to motorists at nighttime by reflecting light
from the motor vehicle's headlamps back to the motor vehicle
driver. The bright image displayed by the retroreflective article
ultimately gives motorists more time to react.
[0003] Sometimes the retroreflective articles are colored for
aesthetic reasons or to provide enhanced contrast for better
daytime visibility. Frequently, fluorescent colors are used in
conjunction with retroreflective sheeting to make the sheeting more
conspicuous under daytime viewing conditions (see, for example,
U.S. patent application Ser. No. 08/587,339 or corresponding
International Publication WO 95/31739 and U.S. Pat. Nos. 3,830,682,
5,387,458, and 5,695,853).
[0004] Because retroreflective articles are regularly used on
clothing, they must be able to withstand laundering
conditions--otherwise, the articles cannot continue to serve their
safety function after repeated washings. Investigators at the 3M
Company who design retroreflective articles for use on clothing are
aware of this problem, and they have developed launderably-durable
retroreflective articles so that persons who wear retroreflective
clothing remain conspicuously visible after their clothing has been
laundered many times. U.S. Pat. Nos. 5,200,262, 5,283,101,
5,474,827, 5,645,938, 5,738,746, and 5,812,317 disclose examples of
launderably durable retroreflective articles developed at 3M. These
products typically comprise optical elements that are partially
embedded in a specially formulated binder layer.
[0005] Investigators also recognize that the need to develop
launderably durable retroreflective articles is particularly
pronounced for clothing that regularly is worn in harsh
environments. Examples of such clothing include firemen's jackets
and construction workers' safety vests (see, for example, U.S. Pat.
No. 4,533,592 to Bingham). These garments tend to get very dirty,
very often, and therefore they are frequently cleaned under
industrial laundering conditions. Industrial laundering conditions
involve wash temperatures as high as 40 to 90.degree. C. (105 to
190.degree. F.) and pH values of 10 to 13. Some of the launderably
durable retroreflective articles disclosed in the 3M patents
mentioned above are capable of withstanding the more stringent
industrial wash conditions.
[0006] In some retroreflective articles, a colored appearance has
been achieved by placing a colored polymeric layer on top of the
optical elements. Retroreflective articles that contain optical
elements partially embedded in a polymeric top layer (also referred
to as a cover film) are commonly referred to as "enclosed lens"
retroreflective articles. In addition to providing color, the
polymeric top film allows the article to be easily wiped clean, and
the articles generally exhibit good retroreflectivity when wet.
Examples of patents that disclose colored top films include U.S.
Pat. Nos. 5,069,964 and 5,378,520. In these retroreflective
articles, a dye or pigment is added to the top film. Commercially
available products that have a colored top film include 3M
Scotchlite.TM. 7960 and 7987 brand products.
[0007] An alternative to enclosed lens retroreflective articles are
"exposed lens" retroreflective articles, which have the optical
elements exposed to the ambient environment--that is, the optical
elements are not covered by a polymeric top film. These articles
generally include an exposed layer of transparent microspheres, a
polymeric binder layer, and a reflective layer. The transparent
microspheres are partially embedded in the binder layer and are
partially exposed to the atmosphere, and the reflective layer is
generally disposed between the microspheres and the binder
layer.
[0008] Another kind of retroreflective article is an "encapsulated
lens" retroreflective article. These articles are similar to
enclosed lens articles in that they employ a top film over the
layer of microspheres. Encapsulated lens retroreflective articles,
however, differ from enclosed lens articles by having the top film
encapsulate a pocket of air above the layer of microspheres. U.S.
Pat. Nos. 4,025,159 to McGrath, 4,896,943 to Tolliver et al.,
4,897,136 to Bailey et al., and 5,069,964 to Tolliver et al.
disclose examples of encapsulated lens type products. In one
variation of an encapsulated lens retroreflective sheeting
(disclosed by Tung et al. in U.S. Pat. No. 4,678,695), transparent
microspheres are partially embedded in a binder layer, and a clear
or colored top film is disposed over the microspheres. The binder
layer may be impregnated with a white pigment, or, alternatively,
with a colored pigment to make a sheeting that displays a
corresponding daytime color and exhibits nighttime reflection.
[0009] These three systems, exposed lens, enclosed lens, and
encapsulated lens sheetings, have various advantages and
disadvantages relative to one another, and coloring techniques
applicable to one system are not necessarily applicable to the
other. Exposed lens articles tend to be more flexible and simpler
in construction but cannot be colored simply by including a dye in
a top film because the articles have no top film. Enclosed lens and
encapsulated lens articles, while being somewhat easier to color,
generally suffer from the drawback of not being very useful at high
temperatures because the polymeric top film can melt. Enclosed lens
and encapsulated lens articles, therefore, do not rate as high as
exposed lens articles when considering candidates for use on
firefighters' jackets.
[0010] A variety of methods, however, have been employed to impart
color to exposed lens retroreflective articles. In U.S. Pat. No.
3,700,305, for example, Bingham discloses an exposed lens
retroreflective article that has alternating layers of different
refractive index dielectric materials coated on glass microspheres.
A colored layer, such as a fluorescent layer, is applied behind the
dielectric reflector. Because the dielectric reflector is
essentially transparent under daytime viewing conditions, the
fluorescent layer imparts a daytime fluorescent color to the
article. Under nighttime or retroreflective viewing conditions,
however, the article is basically incapable of displaying the color
of the underlying colored layer because incident light never
strikes that layer: it is first reflected by the dielectric
reflector back towards the light source. The patent is silent
regarding durability under home wash or industrial laundering
conditions.
[0011] Other methods of coloring an exposed lens retroreflective
article are discussed briefly in U.S. Pat. Nos. 3,758,192,
4,102,562, and 5,200,262. In U.S. Pat. No. 3,758,192, Bingham
discloses an exposed lens retroreflective article that has
transparent microspheres partially embedded in a binder layer that
contains flakes of nacreous (pearlescent) pigment and other various
pigments or dyes. While this product can display a colored
retroreflective image, there is nothing in the patent which shows
that the product would be industrial wash durable. In U.S. Pat. No.
4,102,562 to Harper et al., an exposed lens retroreflective article
is disclosed that can display a colored imagewise pattern. The
article has transparent microspheres coated with a transparent
dielectric mirror prepared as described in U.S. Pat. No. 3,700,305
to Bingham. An ink layer that contains a pigment and a melamine is
applied behind the reflective layer (see Example 2). Harper et al.
state that the melamine reacts with the epoxide moiety of the
adhesion promoting silane (see Example 2). Because the ink layer is
disposed behind the reflective layer, the article, while being able
to display the colored image under daytime viewing conditions, is
not capable of displaying a colored retroreflective image. The
patent also does not show that the retroreflective articles would
be durable under industrial wash conditions. Wu-Shyong Li, in U.S.
Pat. No. 5,200,262, partially embeds transparent microspheres in a
binder layer that may be colored by a pigment or dye, preferably a
black dye such as a chromium-azo dye. Li suggests the use of a
metal layer or dielectric material as a reflector. The reflector is
located on the embedded portion of the transparent microspheres.
When a metal reflective layer is used, the color of the underlying
binder layer is not noticeable under daytime or nighttime viewing
conditions. And when a dielectric reflector is used, the color of
the underlying binder layer is not noticeable under nighttime
(i.e., retroreflective) viewing conditions. Li's product is,
however, designed to withstand industrial wash conditions.
[0012] Ulf Olsen, in U.S. Pat. Nos. 5,344,705, 5,503,906, and
5,620,613, discloses exposed lens retroreflective articles that
have a color layer printed on the embedded portion of a layer of
transparent microspheres. The color layer typically contains a
transparent pigment or dye that is substantially uniformly
dispersed in a transparent resin. The color layer is disposed
between the microspheres and a reflective layer, which reflective
layer comprises reflective flakes in a transparent resin. Olsen
also discloses that the color layer and the reflective layer may be
replaced by a colored reflective layer comprising both colorant and
reflective flakes in a transparent resin. While this product can
display a colored image under retroreflective conditions, it does
not indicate that good wash durability can be achieved under
industrial wash conditions.
[0013] In U.S. Pat. Nos. 5,510,178, 5,612,119, 5,679,198, and
5,785,790, Ulf Olsen describes an exposed lens retroreflective
product that has an imagewise colored coating disposed behind a
transparent dielectric mirror that is coated on the backside of
microspheres partially embedded in a binder layer. The colored
image in this product is, however, not noticeable under
retroreflective conditions; it can only be seen under daytime
lighting conditions.
SUMMARY OF THE INVENTION
[0014] The present invention provides a new, exposed lens
retroreflective article that can exhibit color under
retroreflective conditions and that can demonstrate extraordinary
durability under industrial wash conditions. In brief summary, the
exposed lens retroreflective article comprises a layer of optical
elements that are partially embedded in a colored layer that
contains reflective flakes and a dye. The dye is covalently bonded
to a polymer. Unlike conventional colored layers, which contain
pigments or dyes that are physically suspended within a polymeric
matrix, the dye in the colored layer of the present invention is
connected to the polymer molecule by a covalent bond that is
believed to prevent the dye from washing out of the material even
under the harsh conditions of industrial laundering.
[0015] In another aspect, the present invention provides a new
transfer article for supplying a retroreflective article to a
garment assembler. In a further aspect, the invention provides an
article of clothing that has the inventive retroreflective article
disposed on its outer surface.
[0016] The colored, exposed lens retroreflective articles of the
invention can provide good retroreflectivity and color even after
multiple episodes of industrial laundering. The inventive articles
also can display bright and intense colors. The laundering
durability and good color performance makes the articles suitable
for use on safety garments such as construction workers' safety
vests and firefighters' jackets.
[0017] The invention further provides a method of making a
retroreflective article in which a precursor color coating contacts
optical elements. The precursor color coating comprises reflective
flakes, a polymer precursor, and a reactive dye. The reactive dye
has a functional group or groups that will react with the polymer
precursor. The precursor color coating preferably does not contain
solvent. The inventive methods are advantageous over conventional
methods that use solid colorants (which may impart undesirable
stiffness to a retroreflective article) and are advantageous over
methods that use unreactive liquid colorants and plasticizers
(which have a tendency to migrate out of articles during
laundering). The present invention can achieve a colored daytime,
and possibly colored nighttime image without the use of such
ingredients.
[0018] In preparing colored, reflective layers it has been known
that the higher the loading level of reflective flakes, the higher
the reflectivity--and, likewise, the higher the loading level of
colorants, the deeper the color. A practical limitation to the
loading level of solid pigments is an increase in viscosity whereby
the mixture no longer flows and makes mixing and coating difficult
or impossible. Poor processability of a high viscosity mixture can
lead to poor physical properties of the final reflective layer. In
the past, an answer to this problem typically has been to add
solvent to decrease coating solution viscosity. In the inventive
method, a reactive liquid colorant can be used, which enables
higher levels of reflective flakes and colorant to be used without
sacrificing color or physical properties.
[0019] The present invention also includes a method for making
retroreflective articles that does not use a solvent and that
obviates the use of a temporary carrier for the optical elements.
In this method, the optical elements are applied onto a precursor
color coating layer comprising a dye, reflective flakes, and
reactive prepolymer components. After the optical elements are
applied, the precursor color coating layer is cured. The precursor
color coating layer does not contain a solvent that would have to
be disposed of in an environmentally sound manner. By eliminating
the cost and waste associated with solvent use and by eliminating
the need for a temporary carrier for the optical elements, this
method can provide processing and cost benefits over known methods
of making retroreflective articles.
GLOSSARY
[0020] In reference to the invention, the following terms have the
meanings set forth below:
[0021] A "binder layer" is a polymeric layer that can add
structural integrity to the retroreflective article and may provide
assistance in structurally supporting a layer of partially embedded
optical elements.
[0022] A "colored layer" is a layer that is not colorless or
clear.
[0023] "Covalent bonds" are those bonds in which valence electrons
are shared, examples include carbon-carbon, carbon-nitrogen, and
carbon-oxygen bonds.
[0024] A "chromophore" means any chemical group, such as the azo
group, that gives color to a compound.
[0025] A "dye" is an organic or organometallic molecule or moiety
that contains a chromophore that absorbs light of a particular
wavelength(s) to impart color to the colored layer. In the
inventive retroreflective article, the dye shares covalent bond(s)
with a polymer.
[0026] "Exposed lens retroreflective articles" are retroreflective
articles that have optical elements partially embedded in the
retroreflective article and partially exposed to the
atmosphere.
[0027] "Optical elements" are light transmissive elements that are
capable of affecting the direction of light that enters the
elements so that the light ultimately can be returned toward the
light source.
[0028] "Polymer" means a molecule that is made up of at least five
repeating units that are regularly or irregularly arranged.
[0029] "Polymeric" means containing a polymer.
[0030] A "polymer precursor" refers to a composition that comprises
reactive monomers, oligomers, and/or polymers that are capable of
reacting with the reactive dye. During curing, the reactive
monomers, oligomers and/or polymers will react to form a higher
molecular weight polymeric material.
[0031] "Reflective flakes" are solid materials that are composed of
a reflective material, capable of suspension in a polymer and that
have some surfaces that are larger than the wavelength of visible
light.
[0032] "Retroreflective" means having the characteristic that
obliquely incident incoming light is reflected in a direction
antiparallel (180 degrees) to the incident direction, or nearly so,
such that an observer at or near the light source can detect the
reflected light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In the drawings:
[0034] FIG. 1 is a cross-sectional view of a retroreflective
article 10 in accordance with the present invention;
[0035] FIG. 2 is a cross-sectional view of a transfer article 20 in
accordance with the present invention; and
[0036] FIG. 3 illustrates a safety vest 40 that displays a
retroreflective article 10 in accordance with the present
invention.
[0037] FIGS. 1-3 generally depict articles of the invention and are
not drawn to scale.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0038] FIG. 1 illustrates an exposed lens retroreflective article
10 that includes optical elements such as microspheres 12. The
microspheres 12 are partially embedded in a colored layer 14. The
colored layer 14 contains reflective flakes 16 that are suspended
in polymeric material 18. Incident light I that strikes the
retroreflective article's front surface 26 passes through the
microspheres 12 and is reflected by reflective flakes 16 to again
reenter the microspheres 12, where the direction of the light is
then altered to return toward the light source as noted by
reflected light beam R. To provide a colored daytime appearance,
the polymeric material 18 includes a dye that is covalently bonded
to a polymer.
[0039] FIG. 2 illustrates a transfer article 20 that is used to
make a retroreflective article 10. An adhesive layer 22 and
temporary carrier 24 (a strippable layer) are also shown. In a
typical application, the adhesive layer 22 is bonded to a fabric
substrate (not shown) and the article 10 is attached to an article
of clothing. Before or after attaching the retroreflective article
10 to an article of clothing, the temporary carrier 24 is removed.
The article 10 may also be attached to the clothing without an
adhesive layer 22 by directly sewing the retroreflective article 10
to a fabric substrate or to an article of clothing. If a binder
layer (not shown) is present, the binder layer typically comprises
a polymer and may contain other materials. The binder layer adheres
to the colored layer and may also adhere to an adhesive layer or a
fabric backing (not shown). See U.S. Pat. No. 5,812,317 to
Billingsley et al. for a disclosure of a binder layer that may
suitably be used in the present invention.
[0040] The optical elements used in the invention preferably are
microspheres that are substantially spherical in shape to provide
uniform and efficient retroreflection. The microspheres preferably
also are highly transparent to minimize light absorption so that a
large percentage of incident light is retroreflected. The
microspheres often are substantially colorless but may be tinted or
colored in some other fashion. The microspheres may be made from
glass, a non-vitreous ceramic composition, or a synthetic resin. In
general, glass and ceramic microspheres are preferred because they
tend to be harder and more durable than microspheres made from
synthetic resins. Examples of microspheres that may be useful in
this invention are disclosed in the following U.S. Pat. Nos.:
1,175,224, 2,461,011, 2,726,161, 2,842,446, 2,853,393, 2,870,030,
2,939,797, 2,965,921, 2,992,122, 3,468,681, 3,946,130, 4,192,576,
4,367,919, 4,564,556, 4,758,469, 4,772,511, and 4,931,414.
[0041] The microspheres typically have an average diameter of about
30 to 200 micrometers, and preferably of about 50 to 150
micrometers. Microspheres smaller than this range tend to provide
lower levels of retroreflection, and microspheres larger than this
range may impart an undesirably rough texture to the
retroreflective article or may undesirably reduce its flexibility.
Microspheres used in the present invention typically have a
refractive index of about 1.2 to 3.0, preferably about 1.6 to 2.2,
and more preferably about 1.7 to 2.0.
[0042] A variety of polymer forming reagents can be used in the
polymer precursor to form the colored layer. Polyols and
isocyanates can be reacted to form polyurethanes; diamines and
isocyanates can be reacted to form polyureas; epoxides can be
reacted with diamines or diols to form epoxy resins; acrylate
monomers or oligomers can be polymerized to form polyacrylates;
diacids can be reacted with diols or diamines to form polyesters or
polyamides. Examples of commercially available polymer forming
reagents that may be used in forming the colored layer include:
Vitel.TM. 3550 available from Bostik Inc., Middleton, Mass.;
Ebecryl.TM. 230 available from UBC Radcure, Smryna, Ga.;
Jeffamine.TM. T-5000, available from Huntsman Corporation, Houston,
Tex.; CAPA 720, available from Solvay Interlox Inc., Houston Tex.;
and Acclaim.TM. 8200, available from Lyondell Chemical Company
(formerly Arco Chemical Co.), Houston, Tex. Examples of reactive
polymers useful in forming the colored layer include
hydroxyalkylenes, polymeric epoxides such as polyalkylene oxides,
and copolymers thereof. Examples of preferred polyurethane forming
methods (into which reactive dyes can be incorporated) are
described by Crandall in U.S. Pat. No. 5,645,938, U.S. patent
application Ser. No. 08/797,062, and PCT published application WO
96/16343, and by Fleming in U.S. patent application Ser. No.
08/777,718, and PCT published application WO 98/28642. Preferably,
the organic polymer to which the dye is bonded is a polyester
polyurethane, polyether polyurethane, or a polyurethane that
includes a block copolymer of polyether and polyester units.
[0043] The polymer precursor can also include an acrylate monomer
as a reactive diluent such that the acrylate monomer polymerizes
via free-radical polymerization and the other reactive components
such as polyols and isocyanates polymerize via a condensation
polymerization. The polymerizations may occur contemporaneously.
The reactive diluent allows for a higher solids loading level
without the viscosity problems associated with handling higher
viscosity solutions. It also eliminates the need for solvent and
the problems associated with removing the solvent.
[0044] The polymer that is used in the colored layer may have
functional groups that allow the polymer to be linked to a silane
coupling agent, or the reactants that form the polymer may possess
such functionality. For example, in producing polyurethanes, the
starting materials may possess hydrogen functionalities that are
capable of reacting with an isocyanate-functional silane coupling
agent; see for example, U.S. Pat. No. 5,200,262 to Li.
[0045] Reactive dyes can be used in forming the colored layer. As a
percentage of starting materials, the composition used to prepare
the colored layer preferably comprises 0.1 to 40 weight % reactive
dye, more preferably 0.5 to 20 weight %, and still more preferably
1 to 10 weight % reactive dye. Preferably, the reactive dye is
functionalized with reactive groups such as amine, hydroxy, thiol,
acylate, and epoxy. More preferably, the reactive dye has at least
two reactive groups, such as dihydroxy, since two reactive groups
allow for extension of a polymer chain while a single reactive
group, such as a monohydroxy dye, would result in chain
termination. Examples of commercially available reactive dyes that
may be used in forming the colored layer include Reactint.TM. X3LV,
X15, 17AB, X41LV, X64, X77 X80LT, X95AB, and X96 dyes available
from Milliken Chemicals, Spartanburg S.C. The dye preferably does
not contain heavy metals, particularly metals that may pose
toxicity problems such as lead, cadmium, chromium, or mercury (see
U.S. Pat. No. 5,286,682 to Jacobs et al.).
[0046] Examples of reactive polymer/dye systems useful in forming
the colored layer include those described in U.S. Pat. Nos.
3,994,835, 4,026,931, 4,137,243, 4,284,729, 4,507,407 and
4,846,846. In one preferred example, a colored layer is made in a
reaction in which a polyether or polyester is reacted with an
organic polyisocyanate and a primary-dihydroxyl-functionalized
dye.
[0047] The colored layer contains reflective flakes suspended in a
polymeric material. Preferred reflective flakes include aluminum
flakes, mica platelets coated with titania and/or iron oxide, and
plate-like crystals of bismuth oxychloride. The flakes typically
range in thickness from 0.1 to 0.5 micrometers (.mu.m) and are up
to about 500 .mu.m in length. The colored layer preferably contains
0.5 to 70 weight % reflective flakes, more preferably 10 to 50
weight %, and still more preferably 20 to 40 weight %. Examples of
reflective flakes usable in the present invention include those
described in U.S. Pat. Nos. 3,758,192 and 4,763,985. Examples of
commercially available reflective flakes that may be used in the
colored layer include Afflair.TM. available from EM Industries,
Hawthorne, N.Y. and Mearlite.TM. available from Mearl Corp.,
Briarcliff Manor, N.Y. Preferred commercially available flakes
include Afflair.TM. 100, 111, 183, 201, 299, 300, 500, and 600,
Mearlite.TM. Ultra Bright, Mearlite.TM. Ultrafine, and Mearlite.TM.
G. The colored layer can contain one type or several types of
reflective flakes depending on the desired appearance and
characteristics of the final article. The combination of reflective
flake and reactive dye is also an important consideration. For
example, Afflair.TM. 111 imparts a silver-white appearance and
adding Reactint Blue 17AB dye gives a white-blue appearance.
Afflair 221.TM. imparts a blue color; so, combining Afflair 221
with Reactint Blue 17AB produces a deep blue color.
[0048] The retroreflective article may have more than one colored
layer if, for example, an image or some type of indicia is
required. The colored layer is preferably continuous or
substantially continuous, thus providing a solidly colored
retroreflective article. The colored layer is preferably capable of
supporting optical elements and is typically a fluid-impermeable,
polymeric, sheet-like layer that has an average thickness of about
1 to 250 .mu.m. Preferably, the average thickness is about 50 to
150 .mu.m. Thicknesses less than 50 .mu.m may be too thin to adhere
to both a substrate and the optical elements, and thicknesses
greater than 150 .mu.m may unnecessarily stiffen the article and
add to its cost.
[0049] For economy and flexibility, the colored layer is typically
preferred to be used without a binder layer; however, for greater
stiffness or other reasons, the retroreflective article may include
a binder layer that is disposed on the colored layer on the side
opposite the optical elements. In place of, or in addition to, a
binder layer, the retroreflective article may include a
melt-processable thermoplastic or pressure sensitive adhesive
layer, and optionally may include a release liner.
[0050] The colored layer and/or binder layer may comprise polymers
that contain units such as urethane, ester, ether, urea, epoxy,
carbonate, acrylate, acrylic, olefin, vinyl chloride, amide, alkyd,
or combinations thereof. The colored layer and the binder layer may
also contain other ingredients such as fillers, stabilizers (for
example, thermal stabilizers and antioxidants such as hindered
phenols and light stabilizers such as hindered amines or
ultraviolet stabilizers), flame retardants, flow modifiers (for
example, surfactants such as fluorocarbons or silicones),
plasticizers, and elastomers. Care should be taken when selecting
such additives because some may detrimentally affect laundering
durability. For example, high levels of flame retardants such as
melamine pyrophosphate may have a deleterious effect on the
article's retroreflective performance after laundering.
[0051] The exposed lens retroreflective articles of the invention
can provide a variety of desirable properties. Although the
articles can have a retroreflectivity of less than 10
candellas/lux/meter.sup.2, the articles typically have an initial
retroreflectivity (that is, before being laundered), as measured by
the procedure described in the Examples, of at least 50
candellas/lux/meter.sup.2, more preferably at least 60
candellas/lux/meter.sup.2, and retain at least 10%, more preferably
at least 20% of their retroreflected brightness after 20 cycles of
the Industrial Laundering Procedure described below.
[0052] The exposed lens retroreflective articles of the invention
preferably have color retention, as measured by the Color
Measurement Procedure described below, such that neither the x or y
color coordinates on the standard CIE 1931 chromaticity diagram
change (initial color--color after washing) by more than 0.02 and Y
does not change more than 20%, more preferably x or y do not change
more than 0.01 and Y does not change more than 10%, and still more
preferably x or y do not change more than 0.005 and Y does not
change more than about 5%, after 20 cycles of the Industrial
Laundering Procedure described below. This color measurement was
developed by the Commission Internationale de l'Eclairage (CIE) and
is based on the fact that any color can be represented as a
combination of three primary colors each of which varies as a
function of wavelength in the visible spectrum. A color can be
objectively specified by the coordinates x, y and z of the
chromaticity diagram that are needed to match a particular color.
The values of X, Y, and Z are measures of the amount of color
having CIE coordinates x, y, and z and are defined by the
equations: Y=y(X+Y+Z), X=x(X+Y+Z), and Z=z(X+Y+Z). Since x+y+z=1,
and substituting Y/y=(X+Y+Z) into the foregoing equations shows
that a color (with intensity) can be completely defined by x, y and
Y. Another commonly used measurement of color in the CIE system is
E*. The exposed lens retroreflective articles of the invention
preferably have a color retention, as measured by the Color
Measurement Procedure described below, such that the change in E*
(initial color--color after washing, or E*) is less than 8, and
more preferably E* is less than 4 after 20 cycles of the Industrial
Laundering Procedure described below. The CIE color system is
described in references such as Wyszecki and Stiles, Color Science,
2nd ed., John Wiley & Sons, 1982; and Judd, Color in Business,
Science, and Industry, John Wiley & Sons, 1952.
[0053] As shown in FIG. 2, a retroreflective article 10 can be made
by first forming transfer article 20. In producing the transfer 20,
a multitude of microspheres 12 can be cascaded onto a temporary
carrier 24 in a desired temporary arrangement. A "carrier" is a web
onto which the optical elements are temporarily positioned so that
the colored layer can be applied onto it. The carrier is temporary
because it is removed before the retroreflective article 10 is
used. Microspheres 12 preferably are packed as closely as possible
on the carrier 24 and may be so arranged by any convenient process,
such as printing, screening, cascading, or with a hot can roll. The
microspheres 12 are partially embedded in the carrier 24, typically
to about 30 to 60 percent of the microspheres' diameter. The
portions of the microspheres 12 that are not embedded in carrier 24
protrude from it so that they can subsequently receive the colored
layer.
[0054] Carrier 24 can include a heat softenable polymer layer 30 on
a paper sheet 32. Examples of useful polymer layers 30 for carrier
web 24 include: polyvinyl chloride; polyolefins such as
polyethylene, polypropylene, and polybutylene; and polyesters; et
cetera. For a further discussion of applying microspheres to the
carrier web, see U.S. Pat. Nos. 4,763,985; 5,128,804; and
5,200,262.
[0055] Polymeric layer 18 retains microspheres 12 in the desired
arrangement. Depending in part on the characteristics of the
carrier web 28 and microspheres 12, it may be desirable to
condition carrier 24 and/or microspheres 12 by applying selected
release agents or adhesion promoters to achieve desired carrier
release properties.
[0056] After the microspheres are partially embedded in temporary
carrier 24, the precursor color coating is placed on the exposed
portions of the microspheres. The colored layer can be made by
reacting polymers, oligomers, or monomers with the appropriate,
chemically reactive dye. This can be accomplished, for example, by
applying a solution of prepolymer components and reactive dye onto
the protruding portions of the microspheres. A coupling agent
(typically a silane, but may be other compounds such as titanate or
zirconate coupling agents) may be added for enhanced adhesion to
the microspheres. After applying the solution, it preferably is
only partially cured and a fabric preferably is embedded in the
color layer composition before curing. The fabric is secured to the
color layer on the side opposite the microspheres 12.
Alternatively, if a fabric is not used, an adhesive may be applied
to the colored layer or to a binder layer (or to the binder layer
composition before curing).
[0057] As an alternative to the above-described process utilizing a
carrier for the microspheres, the precursor color coating can be
applied to a substrate such as fabric, a release layer, or a
transfer film (such as a thermoplastic polyester or polyurethane
film), and the microspheres can be spread over the uncured or only
partially cured precursor color coating. In a related technique
(see U.S. Pat. No. 3,758,192, col. 10, line 60-col. 11, line 2),
Bingham states that solvent is required to allow leafing of the
nacreous pigment. The bead-spreading method of the present
invention avoids the use of a solvent in forming the colored layer.
By using reactive dyes and polymer precursors rather than
conventional pigments and polymers dissolved in solvent, the
inventive methods allow the formation of reflecting colored layers
having desirable properties (as described herein) without the
necessity of using solvents. For example, the solventless precursor
color solutions of Examples 1-4 can be utilized in a bead-spreading
technique. Also the bead-spreading technique illustrated in
Examples 5 and 6 can be conducted equally successfully without the
addition of a solvent such as methylethyl ketone.
[0058] In the case of reacting a dye with polyisocyanates, the
reactive functional groups on the dye compound may include
hydroxyls, amines, and/or thiols. A retroreflective article having
good color and retroreflectivity durability properties can be
obtained by reacting a polyether polyol, such as Acclaim.TM. 2220,
with an isocyanate, a hydroxyl-functionalized reactive dye, and an
isocyanatosilane. The reactive dye and isocyanate react with the
polyols to form a colored, crosslinked polymer in a hardened layer.
The isocyanatosilane binds to the surface of the microspheres and
reacts with the polymer, and thus binds the transparent
microspheres to the colored layer.
[0059] The inventive retroreflective articles may be applied to
substrates using mechanical methods such as sewing. In some
applications, however, it is desired to secure the article to the
substrate by an adhesive layer. The adhesive layer can be, for
example, a pressure-sensitive adhesive, a heat-activated adhesive,
or an ultraviolet-radiation-activate- d adhesive.
[0060] The substrate bearing the retroreflective article can be
located on the outer surface of an article of clothing, enabling
the retroreflective article to be displayed when the clothing is
worn in its normal orientation on the person. The substrate may be,
for example: a woven or nonwoven fabric such as a cotton fabric; a
polymeric layer including nylons, olefins, polyesters, cellulosics,
urethanes, vinyls, acrylics, rubbers; leather; and the like.
[0061] FIG. 3 illustrates a safety vest 40, displaying a
retroreflective article 10 that is in the form of an elongated
sheeting or strip, typically one to three inches wide. Safety vests
often are worn by road construction workers to improve their
visibility to oncoming motorists. These kinds of vests frequently
come into contact with dirt and grime and therefore need to be able
to withstand harsh cleaning conditions so that the vest can be
reused a number of times.
[0062] Although a safety vest 40 has been chosen for illustration,
the article of clothing of the invention may come in a variety of
forms. As the term is used herein, "article of clothing" means a
launderable item of wearing apparel sized and configured to be worn
or carried by a person. Other examples of articles of clothing that
may display retroreflective articles of the invention include
shirts, sweaters, jackets (e.g. firefighters' jackets), coats,
pants, shoes, socks, gloves, belts, hats, suits, one-piece body
garments, bags, backpacks, et cetera.
[0063] Advantages and other properties and details of this
invention are further illustrated in the following Examples. It is
to be expressly understood, however, that while the examples serve
this purpose, the particular ingredients and amounts used and other
conditions are not to be construed in a manner that would unduly
limit the scope of this invention. For example, while the Examples
illustrate inventive methods that produce products on an individual
basis, the processes can also be performed continuously. The
Examples selected for disclosure are merely illustrative of how to
make a preferred embodiment of the invention and how the articles
can generally perform.
EXAMPLES
[0064] The following tests and procedures were used in the
examples.
[0065] Industrial Laundering Procedure
[0066] Launderability was evaluated by washing and drying a piece
of fabric to which the retroreflective article was applied. The
combined sequence of washing and drying is referred to as a cycle.
The samples were washed using a Milnor System 7 Washing Machine
Model 30015M4G from Pellerin Milnor Corp. In accordance with
program no. 7 for heavily soiled, colored fabrics. The fabric was a
100 percent cotton towel, and the retroreflective article was
secured to the fabric by sewing. The washer was loaded with enough
pieces (approximately 80) of fabric (about 45 centimeters (cm) by
75 cm) to make a 28 pound load including from one to four pieces of
fabric having several (typically about 5) retroreflective articles
of the invention about 5 by 15 centimeters in size secured
thereto.
[0067] The cleaning agents used were 90 ml of Lever Tech Ultra, a
detergent (from Lever Industrial, North Charleston, S.C.)
containing, by weight, approximately 10 percent potassium
hydroxide, 25 percent potassium citrate, and 2 percent ethoxylated
lauryl alcohol (the remaining contents are not known by the
inventors), and 120 ml of Lever Tech Booster (a pH builder also
from Lever Industrial) containing 20 percent sodium hydroxide (the
remaining contents are not known by the inventors). In Program No.
7 the following steps are carried out to complete the washing
portion of a cycle:
1 Operation Time (minutes) Suds 20.5 Flush 2 Flush 7 Flush 7 Flush
2 Hot Rinse 2 Split Rinse 2 Cold Rinse 4 Extract 6 Total 52.5
(55.0*) *Total time in minutes, which includes approximate fill
times.
[0068] In the suds step, hot water (68 liters at 80.degree. C.) and
the cleaning agents are introduced into the machine washing basket
under agitation. In the flush steps, fresh hot water (68 liters at
80.degree. C.) is added to the washing basket after the same amount
of the old water containing the cleaning agents is purged.
[0069] The rinse steps essentially are the same as the flush steps
except the water becomes cooler. In the first rinse, the water is
approximately 80.degree. C., in the second rinse (split rinse), the
water is approximately 46.degree. C., and in the final cold rinse,
the water is approximately 18.degree. C. The washing basket is
agitated during the flush and rinse steps. In the extract step, the
machine undergoes a high-speed spin cycle to remove water from the
washed samples. After washing but before being tested for
retroreflectivity, the samples were dried by either Procedure 1 in
a Maytag.TM. home dryer at 60.degree. C. (140.degree. F.) on
regular setting for about 30-35 minutes or by Procedure 2 in a
drying oven (Despatch Style V-27 from Despatch Oven Company) at
177.degree. C. (350.degree. F.) for 10 minutes. Procedure 1 is
commonly recognized as being a tumble drying operation, whereas
Procedure 2 is designed to represent a tunnel finish operation.
Completion of the drying procedure marks the completion of an
industrial wash cycle. After the designated number of cycles, the
retroreflective brightness at the middle of each sample was
determined.
[0070] Retroreflective Brightness
[0071] Retroreflective brightness was measured according to ASTM
Test Specification E-810-94, entitled "Standard Test Method for
Coefficient of Retroreflection of Retroreflective Sheeting", using
an observation angle of 0.2.degree. and an entrance angle of
-4.degree.. The retroreflective brightness is reported as a
Coefficient of Retroreflection in units of candelas per lux per
square meter (candelas/lux/m.sup.2). An "initial" Coefficient of
Retroreflection is one that has been ascertained before the
retroreflective article has been washed.
[0072] Color Measurement Procedure
[0073] CIE color coordinates, as described in ASTM E308, were
measured using a Hunter LabScan color measurement apparatus using a
D65 light source, with 0/45.degree. geometry. The term 0/45 means
that the illuminating light source is shining at the surface at an
angle of approximately 0 degrees from normal to the surface, and
the color measurement is made by looking at an angle of
approximately 45 from normal to the surface. Color measurements
were made on circular samples having diameters of 2.5 centimeters
(1 inch).
2 Component Sources Component Source Washing machine Pellerin
Milnor Corporation, P.O. Box 400, Kenner, Louisiana 70063 Primalux
.TM. and Springs Industries Inc., 420 West White Excellerate .TM.
fabrics Street, Rock Hill, South Carolina 29730 Lever Tech Ultra
.TM. Lever Industrial, North Charleston, detergent South Carolina
29418 Maytag .TM. home dryer Maytag, Newton, Iowa 50208 Acclaim
.TM. 2220 polyether Arco Chemical, New Town Square, polyol
Pennsylvania A-1310 silane OSI Specialties Inc., 39 Old Ridgebury
Road, Danbury, Connecticut 06810 Syn Fac 8009 polyol Milliken
Chemicals, Spartanburg, South Carolina 29304 Capa 720 polyol Solvay
Interlox Inc., Houston, Texas dibutyltinlaurate catalyst Witco
Corp., Greenwich, Connecticut Milliken Reactint .TM. Milliken
Chemicals, Spartanburg, X15 yellow dye, X64 red, South Carolina
29304 dye, and X80 violet dye Afflair .TM. 111 Pearlescent EM
Industries, Hawthorne, New York Flake Mondur ML aromatic Bayer
Corp., Pittsburgh, Pennsylvania diisocyanate Voranol 234-630
x-linker Dow Chemicals Inc., Midland, Michigan FC-430 wetting agent
3M, St. Paul, Minnesota Bemis 5250 transfer film Bemis Associates,
Shirley, Massachusetts adhesive Isooctyl acrylate 3M, St. Paul,
Minnesota Ultrabrite UFI Mearl Corp. Briarcliff Manor, New York
Benzoyl peroxide catalyst Aldrich Chemical Co., Milwaukee,
Wisconsin
Example 1
[0074] A microsphere carrier was prepared in the manner described
in U.S. Pat. No. 5,474,827. Glass microspheres having a refractive
index of about 1.9 and diameters of 40-90 micrometers were cascaded
onto a polyethylene layer carried on a paper backing, in a manner
which encouraged closest packing of the microspheres. The
polyethylene layer was heated, and the microspheres were sunk into
the polyethylene to a depth of about half the diameter of the
microspheres so that a portion of the microspheres remained exposed
above the surface of the polyethylene.
[0075] A colored layer coating solution was prepared by combining
the following ingredients and stirring for 6 hours at 500 rpm with
a propeller mixer:
3 44.42 grams (g) Acclaim .TM. 2220 9.93 g Syn Fac .TM. 8009 3.64 g
Voranol .TM. 234-630 29.05 g Afflair .TM. 111
[0076] Then 43.65 grams of the above polyol/pearlescent solution
was combined with 1.0 g Reactint.TM. X64 red dye, 7.62 g Mondur ML,
1.8 g A-1310, and 2 drops dibutyltinlaurate and stirred by hand.
The A-1310 is a silane coupling agent to promote bead-bonding; the
Syn Fac.TM. is a chain extender to increase elasticity; and the
Voranol.TM. is a cross-linker to increase temperature
stability.
[0077] The resulting precursor color coating solution was coated
onto the microspheres of the beadcoat carrier using a notched bar
coater having the metering bar set at a gap of 6 mils (150 .mu.m)
above the surface of the microspheres. The coating was partially
cured by forced air heating at 105.degree. C. (220.degree. F.) for
three minutes. Fabric was then applied to the softened color layer
and additional curing was conducted at 105.degree. C. (220.degree.
F.) for nine minutes. After 3 days, the carrier web was stripped
away to yield an exposed lens retroreflective fabric that displayed
a red daytime color and that had an initial coefficient of
retroreflection of 69.7 candelas/lux/m.sup.2.
[0078] Color and Retroreflective Brightness were measured before
and after subjecting the sample to 20 Industrial Wash Cycles in a
Milnor industrial washer as described in the Industrial Laundering
Procedure (including both drying procedures). After 20 Industrial
Wash Cycles using drying procedure (1), the article retained 23% of
its retroreflected brightness. After 20 industrial wash cycles
using drying procedure (2), the article retained 41% of its
retroreflected brightness.
[0079] The CIE color coordinates before and after 20 industrial
wash cycles using drying procedures (1) and (2) were as
follows:
4 CIE Coordinates: Y x y Initial Color 22.47 .4142 .3085 Color
After 20 Cycles (1) 24.4 .4323 .3067 Color After 20 Cycles (2)
23.36 .4341 .3105
[0080] The change in E* (procedure 1) was 7.4 and (procedure 2)
6.3.
[0081] This data show that the retroreflective article had
substantial retention of color and retroreflectivity after 20
laundering cycles. The data also shows that the visual aesthetics
of the fabric sample was substantially retained after 20 laundering
cycles.
Example 2
[0082] This example was prepared in the same manner as Example 1
but with the following changes.
[0083] A colored layer coating solution was prepared by combining
the following ingredients and stirring for 2 hours at 500 rpm with
a propeller mixer:
5 40.03 grams (g) Acclaim .TM. 2220 9.94 g Syn Fac .TM. 8009 3.63 g
Voranol .TM. 234-630 15.06 g Afflair .TM. 111
[0084] Then 34.36 grams of the above polyol/pearlescent solution
was combined with 1.05 g Reactint.TM. X15 yellow dye, 7.52 g Mondur
ML, 1.87 g A-1310, and 2 drops dibutyltinlaurate and stirred by
hand. The resulting precursor color coating solution was coated
onto the microspheres of the beadcoat carrier using a notched bar
coater having the metering bar set at a gap of 6 mils (150 .mu.m)
above the surface of the microspheres. The coating was partially
cured by forced air heating at 105.degree. C. (220.degree. F.) for
3 minutes. Fabric was then applied to the softened color layer and
additional curing was conducted at 105.degree. C. (220.degree. F.)
for 16 minutes. After 1 day, the carrier web was stripped away to
yield an exposed lens retroreflective fabric that displayed a
yellow daytime color and that had an initial coefficient of
retroreflection of 45.6 candelas/lux/m.sup.2.
[0085] After 20 Industrial Wash Cycles using drying procedure (1),
the article retained 7% of its retroreflected brightness. After 20
Industrial Wash Cycles using drying procedure (2), the article
retained 14% of its retroreflected brightness.
[0086] The CIE color coordinates before and after 20 industrial
wash cycles using drying procedures (1) and (2) were as
follows:
6 CIE Coordinates: Y x y Initial Color 61.66 .3954 .4487 Color
After 20 Cycles (1) 66.01 .3956 .4525 Color After 20 Cycles (2)
58.74 .4019 .4449
[0087] The change in E* (procedure 1) was 3.7 and (procedure 2)
3.9.
[0088] This data show that the retroreflective article had
substantial retention of color and retroreflectivity after 20
laundering cycles. The data also shows that the visual aesthetics
of the fabric sample was substantially retained after 20 laundering
cycles.
Example 3
[0089] This example was prepared in the same manner as Example 1
but with the following changes.
[0090] A colored layer coating solution was prepared by combining
the following ingredients and stirring for 3 hours at 500 rpm with
a propeller mixer:
7 40.06 grams (g) Acclaim .TM. 2220 9.95 g Syn Fac .TM. 8009 3.66 g
Voranol .TM. 234-630 30.01 g Afflair .TM. 111
[0091] Then 41.83 grams of the above polyol/pearlescent solution
was combined with 3.08 g Reactint.TM. X64 red dye, 7.51 g
Mondur.TM. ML, 1.8 g A-1310, and 2 drops dibutyltinlaurate and
stirred by hand. The resulting precursor color coating solution was
coated onto the microspheres of the beadcoat carrier using a
notched bar coater having the metering bar set at a gap of 6 mils
(150 .mu.m) above the surface of the microspheres. The coating was
partially cured by forced air heating at 105.degree. C.
(220.degree. F.) for three minutes. Fabric was then applied to the
softened color layer, and additional curing was conducted at
105.degree. C. (220.degree. F.) for nine minutes. After 1 day, the
carrier web was stripped away to yield an exposed lens
retroreflective fabric that displayed a red daytime color and that
had an initial coefficient of retroreflection of 58.9 candelas per
lux per square meter.
Example 4
[0092] The following components were combined in a glass jar:
[0093] 38.87 g Capa 720
[0094] 5.97 g Syn Fac 8009
[0095] 1.79 g Voranol 234-630
[0096] 0.12 g FC-430
[0097] 19.98 g Afflair 123
[0098] 0.29 g Reacting Violet X80
[0099] The mixture was warmed on a hot plate with stirring at 1200
rpm using a propeller mixer for 14 hours. The mixture was then
degassed under 100 millitorr vacuum for 15 minutes. 33.4 g of the
above mixture was transferred to another jar. 5.15 g Mondur ML, 1.0
g A-1310 and 1 drop dibutyltinlaurate (DBTDL) was added to the
mixture and stirred. The mixture was notch-bar coated onto silicone
release paper and cured in the oven for 3 minutes at 110.degree. C.
(230.degree. F.). The coating on release paper was removed from the
oven and the surface of the coating was flooded with glass
microspheres. The sample was then returned to the oven for 5
minutes.
[0100] The final cured sample had as aesthetically pleasing violet
color and exhibited a coefficient of retroreflection of 64
candelas/lux/m.sup.2. The sample was removed from the release paper
and laminated to a 100% polyester fabric using a Bemis.TM. 5250
transfer film adhesive. The laminating conditions were 20 seconds
at 166.degree. C. (330.degree. F.) and 40 pounds per square inch
(psi). The sample was retested for Retroreflective Brightness and
had an initial coefficient of retroreflectivity of 47
candelas/lux/m.sup.2. After 10 Industrial Washing Cycles (procedure
1), the sample maintained 66% of its initial retroreflectivity.
[0101] Examples 5 and 6 demonstrate the use of an acrylate monomer
as a reactive diluent that polymerizes via free-radical
polymerization while polyols and polyisocyanates polymerize via
condensation polymerization.
Example 5
[0102] Ten (10.0) g isooctyl acrylate (IOA) and 10.0 g Ultrabrite
UFI were added to an 8 ounce jar and rolled on a continuous roller
for 14 hours. Then 19.4 g CAPA 720, 3.0 g Syn Fac.TM. 8009, 0.89 g
Voranol.TM. 234-630, and 10.0 g Ultrabrite.TM. UFI were added to
the mixture. 2.0 g IOA, 0.5 g methylethyl ketone (MEK) and 0.2 g
benzoylperoxide were premixed to dissolve the benzoylperoxide and
this solution was added to the mixture and the mixture rolled on a
roller for 18 hours. 5.3 g Mondur ML, 1.0 g A-1310, 2 drops DBTDL,
and 0.2 g Reactint Yellow X15 were added to the mixture and
stirred. The resulting mixture was notch-bar coated onto silicone
release paper and cured in an oven for 4 minutes at 110.degree. C.
(230.degree. F.). The coating on release paper was removed from the
oven and the surface of the coating was flooded with glass
microspheres. The sample was then returned to the oven for 10
minutes.
[0103] The final cured sample had as aesthetically pleasing yellow
color and an initial coefficient of retroreflection of 130 candelas
per lux per square meter.
Example 6
[0104] Forty (40.0) g isooctyl acrylate (IOA) and 50.0 g Ultrabrite
UFI were added to an 8 ounce jar and rolled on a continuous roller
for 14 hours. 30.0 g of this mixture was transferred to a glass jar
and 19.53 g CAPA 720, 2.95 g Syn Fac 8009, 0.88 g Voranol 234-630,
and 0.4 g Reactint Red X64 were added to the mixture. 2,2 g MEK and
0.2 g benzoylperoxide were premixed to dissolve the benzoylperoxide
and this solution was added to the mixture and the mixture rolled
on a roller for 15 minutes. 5.2 g Mondur ML, 1.0 g A-1310, and 3
drops DBTDL were added to the mixture and stirred. The resulting
mixture was notch-bar coated onto an 80/20 polyester/cotton blend
fabric and cured in an oven for 4 minutes at 110.degree. C.
(230.degree. F.). The coating on the fabric was removed from the
oven, and the surface of the coating was flooded with glass
microspheres. The sample was then returned to the oven for 10
minutes.
[0105] The final cured sample had as aesthetically pleasing red
color and had an initial coefficient of retroreflection of 150
candelas per lux per square meter.
[0106] The disclosures of all patents and patent applications cited
above including those cited in the Background, are incorporated by
reference into this document as if reproduced in full. The
disclosure of cofiled U.S. patent application Ser. No. ______
(attorney docket number 53977USA2A) entitled Retroreflecfive
Article Having A Colored Layer Containing A Dye Covalently Bonded
To A Polymer by Billingsley et al.
[0107] The invention may be suitably practiced in the absence of
any item or element not described above.
* * * * *