Patent Application
20080026193
In the drawings wherein like numerals designate like parts throughout the same:
a-1c depict the colorizing of a retroreflective film or fabric in accordance with the invention.
The following detailed description presents certain embodiments to illustrate the inventive concepts, but which are meant by way of example only and are not intended to limit the scope of the invention in any manner. In accordance with the invention, it has been learned that reflective films or fabrics can be effectively and permanently colorized by the application of a thin translucent colorized coating to the exposed reflective elements. It has further been found that coating compositions with suitable durability for colorizing reflective materials include a combination of components including an amount of a generally transparent pigmented ink, an amount of one or more species of polyurethane materials and a minor amount of a compatible silane material.
It has further been found that the colorizing coating composition requires the use of materials including any solvents which are relatively inert relative to and which do not disturb the reflective element/binder bond of the reflective film or fabric to which the colorized composition is applied. Because the great majority of these fabrics use adhesives which are not affected by water-based systems, these are preferred. However, it will be understood by those skilled in the art that compatibility between the colorizing composition solvent and the reflective element adhesive is the important consideration. The colorizing composition must be such that the integrity of the reflective element layer is not disturbed by the addition of the colorizing overlayer. Thus, a compatible solvent is one that does not affect adhesion of the binder layer. For example, several polyurethane dispersions contain acetone or n-methylpyrrilidone in minor amounts, which do not disturb the integrity of the reflective element layer or the bond between the bead-bond adhesive and the reflective beads.
A further aspect of the invention is that the colorizing compositions are designed to be applied to a variety of types of reflective films or fabrics that have a layer of generally closely packed, very small, exposed micro reflective elements partially imbedded in an adhesive layer with or without additional laminate layers. Particular applications include reflective transfer materials such as iron-on patches or cloth-backed materials to be sewn on a garment. These reflective materials are well known and typically manufactured by one of the techniques mentioned above.
As indicated, a primary result of using the colorizing coating compositions of the invention is the addition and retention of sufficient color to make the resulting retroreflective material esthetically pleasant without any significant reduction in reflectivity. In addition, the colorizing coating compositions of the invention enable these characteristics to endure over the normal laundering life of garments to which they are applied. Additionally, the colorized coating compositions of the present invention are compatible with conventional retroreflective materials and retain sufficient open time to enable conventional saturation/pressing over-printing processes using a squeegee or other devise to remove excess colorizing composition.
This has all been accomplished by the application of a class of colorizing overlayer materials which, according to the present invention, provide the necessary combination of characteristics long sought in colorized retroreflective articles of clothing. The preferred colorizing overlayer includes generally the following components:
1. An amount of a pigmented ink of a desired hue selected from a class of aqueous, pigmented flexographic inks which are colorfast (fade resistant) and as transparent as possible and susceptible to some dilution;
2. An amount of at least one species of polyurethane material of a class including water-based polyurethane emulsions which add improved adhesion and/or elasticity to the composition and which are compatible with the pigmented ink; and
3. A minor amount of a silane additive to further improve composition retention in the material.
a-1c depict the colorizing of a retroreflective film or fabric in accordance with the invention. The material includes an array of glass bead reflective elements 10 partially embedded in an adhesive binder layer 12 and vapor-deposited or chemically coated with a reflective material at 14. A removable liner or release layer is shown at 16. In
The invention will be further described by the following examples which are intended to illustrate the invention and not to limit the scope of the concepts in any manner.
Unless otherwise indicated, the following test methods were used.
Retroreflective brightness was measured using a retroreflectometer at observation angles of about 0.2° and entrance angles of about −4.0°.
The daytime color of the colorized reflective materials were measured using a calorimetric spectrophotometer with 45°/0° optics, a density status setting of T, a standard illuminant D65 light source setting, and a standard observer setting of 2°.
Three colorizing compositions containing a water-based pigmented ink, an aqueous polyurethane dispersion, a silane, and water were used to colorize 3M Scotchlite® 8711 retroreflective heat transfer film. A 13.94 g aliquot of aqueous polyurethane dispersion was diluted with 8.69 g of water and mixed in a glass vial. A 1:1-wt mixture of two different polyurethane dispersion mixtures was used; a semi-crystalline polyester-based polyurethane (Bayer Dispercoll U-54) and a rubbery, amorphous, polyether-based, polyurethane (Witcobond W-170). A water-based brown-pigmented ink was produced by adding equal amounts of water (23.50 g) and commercially-available water-based ink (23.35 g, Environmental Inks and Coatings, Film III, Super Fade Resistant, Brown). Under vigorous stirring with a Teflon-coated magnetic stirbar, 6.71 g of diluted water-based brown pigmented ink was added slowly to the polyurethane dispersion mixture until homogenous. At this time, 0.5 grams of gamma-glycidoxypropyltri-methoxysilane (Silquest A-187) was added while stirring until homogeneous.
In a similar manner, a gold-pigmented colorizing composition was mixed using 5.57 g of polyurethane dispersion, 8.35 g of water, 6.10 g of diluted water-based gold-pigmented ink (from a master batch which was diluted with water, 10.33 grams of gold ink, and 10.40 grams of water), and 0.41 g of gamma-glycidoxypropyltri-methoxysilane.
Each of colorizing compositions were spread onto the glass-bead surface of retroreflective heat transfer films (3M Scotchlite® 8711) using a rubber-squeegee to spread the colorizing composition uniformly across the retroreflective material. In a similar manner, each of the colorizing compositions were applied to two other retroreflective heat transfer films (3M Scotchlite® 8725, and 9720). The colorized films were then dried at room temperature overnight and subsequently laminated onto a polyester-fabric shirt at 350° F., 40 psig, for a dwell time of 20 seconds. After cooling, retroreflectivity measurements were taken. The garment was washed a total of 80 cycles in warm water (105-115° F.), drying every 5th cycle and taking retroreflectivity data. The results of the reflectivity (Ra) and the color (L*a*b*) measurements are in the following table.
In a similar manner to Example 1, a series of 9 different polyurethane dispersions were used to make colorizing compositions. Each polyurethane dispersion was diluted with water to 32%-wt solids content, based on their respective concentrations as received (see Table below).
150 grams of a blue-pigmented ink (Environmental Inks and Coatings, Film III, Super Fade Resistant, Process Blue) was diluted to 75%-wt by adding 50 grams of water and stirring until homogeneous. 20 gram aliquots of colorized compositions were made by adding 10 gram aliquots of diluted blue-pigmented ink to 10 gram aliquots of each polyurethane dispersion. The colorized compositions were then applied to reflective film (3M Scotchlite® 8725) employing the process described in Example 1.
For comparison, 12.0 grams of a 1:1 ratio mixture of U54 and W170 was diluted with 3.0 grams of water. Red pigmented ink (Environmental Inks and Coatings, Film III, Super Fade Resistant, Red) was diluted to 75%-wt by adding 5.0 grams of water to 15.0 grams of red pigmented ink. A 15.0 gram aliquot of the diluted red-pigmented ink was added to the polyurethane mixture and the solution was stirred. A 0.6 gram amount of gamma-glycidoxypropyltri-methoxysilane (Silquest A-187) was then added and the composition was stirred until homogeneous. This red-pigmented color composition was then applied to two different retroreflective heat transfer films (3M Scotchlite® 8725, and Unitica MR-3501) according the process described in Example 1.
These colorized retroreflective films were laminated to a polyester fabric using the method described in Example 1.
The fabric was laundered a total of 25 cycles in hot water (145-155° F.), drying every 5 cycles and taking retroreflectivity data and color data.
A set of 3 colorizing compounds were prepared using the procedure outlined in Example 1. Polyurethane dispersions were added to water to make solutions that were approximately 32%-wt solids.
A 75%-wt solution of blue-pigmented ink (Environmental Inks and Coatings, Film III, Super Fade Resistant, Process Blue) was added to each dispersion in a 1:1 ratio using the process described in the previous examples. A total of 9 different silane compounds were used as additives to each of these three polyurethanes using the method described above to make a total of 27 different colorizing compositions. These silanes are described in the table below. The 27 combinations are named by letter of polyurethane followed by number of silane.
Each of the 27 compositions were applied to 3M Scotchlite® 9720 Industrial Washable reflective film employing the method described in Example 1. The colorized reflective films were then applied to a polyester fabric. The fabric was industrially laundered at water temperatures up to 175° F., using industrial detergents for 5 cycles, and dried. Color and reflectivity data were then obtained.
This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.
| Number | Date | Country | |
|---|---|---|---|
| 60820866 | Jul 2006 | US |
