WO1994006869A2

WO1994006869A2 - An improved process for the production of reflective coatings and materials

Info

Publication number: WO1994006869A2
Application number: PCT/US1993/008997
Authority: WO
Inventors: Michael Ellis
Original assignee: Pioneer Technology, Inc.
Priority date: 1992-09-22
Filing date: 1993-09-22
Publication date: 1994-03-31
Also published as: AU5348094A; WO1994006869A3; GB9220019D0

Abstract

A method for producing hemispherically coated reflex-reflective microspheres for slurry application to a substrate. The method comprises the steps of coating a carrier web with a first adhesive layer; removably embedding a plurality of microspheres into the first adhesive layer, so that one hemisphere of each of the microspheres is embedded therein, the remaining portion of the microspheres remaining exposed from the first adhesive layer; applying a reflective material layer to the exposed hemispherical portion of the microspheres, causing them to be reflex-reflective microspheres; removing the microspheres from the first adhesive layer; and, maintaining the microspheres in water for slurry application.

Description

AN IMPROVED PROCESS FOR THE PRODUCTION OF REFLECTIVE COATINGS AND MATERIALS

FIELD OF THE INVENTION This invention relates to an improved process for producing reflective coatings and materials.

BACKGROUND OF THE INVENTION

Light reflective materials are well known and have been in use for many years as a means of increasing the visibility of pedestrians and road users to oncoming vehicle drivers. However, reflective materials have more usually been incorporated in items of clothing in the form of strips and bands attached to a garment, therefore offering only a limited small area of reflected light. The method of manufacture being a major factor in the end usage, the construction of the materials only allowing the reflecting materials to be used in very limited amounts. The usual method of manufacture being to use transparent glass spheres embedded in a binder adhesive which includes metallic aluminum flakes which act as a reflecting medium, the whole being bonded to a material. This method severely restricts the end use, while being highly light reflective, the materials are not suited to use in large enough amounts as to construct complete sections of garments or whole garments.

There is also a known method of hemispherically coating the transparent glass spheres and incorporating the spheres into a coating which can be applied to dyed untreated fabrics. This method, although offering a light reflecting finish which is suitable for use in the making of whole garments, has only limited light reflectivity and requires complex and costly production methods, particularly when drying the hemispherically coated spheres. Furthermore, the use of the hemispherically coated spheres as may be used at present also appreciably alter the handle of a material and detract from the original appearance of a fabric, offering a grey speckled effect and a stiffening of the material.

It is therefore an object of this invention to provide a method of hemispherically coating transparent microspheres and of applying the microspheres, in various forms to a range of materials to achieve the desired results and overcome the problems shown with the existing methods of coating and application. The aim is to provide a means of accomplishing a reflecting surface which does not appreciably detract from the normal appearance or handle of a material and that can be produced using conventional production systems. It is furthermore an object of the invention to use the transparent spheres to reflect light in various colours and to achieve differing results to suit varying conditions.

SUMMARY OF THE INVENTION

The microspheres used in the process of the present invention are standard glass spheres as used in the making of reflective signs and traffic control products. The spheres should be of a size ranging from between 5 to 250 microns diameter, for the purpose of this process spheres with an average size of 40 microns diameter would normally be used. The spheres should be transparent and have a refractive index of between 1.5 to 2.7, the particular refractive index type used or combination of index types, depends on the intended use of the finished product. For most purposes concerning the process of the present invention, spheres with a refractive index of 1.5, 1.92 and 2.2 are used.

The hemispherical coating of the microspheres is accomplished by coating a carrier web with a first adhesive layer, removably embedding a plurality of microspheres into the first adhesive layer, so that one hemisphere of each of the microspheres is embedded therein, the remaining portion of the microspheres remaining exposed from the first adhesive layer. A reflective material layer is then applied to the exposed hemispherical portion of the microspheres, causing them to be reflex-reflective microspheres. The microspheres are then removed from the first adhesive layer, and maintained in water for slurry application.

The present invention further includes a method for producing a retro-reflective sheeting. This method is accomplished by adhering a substrate to a second layer of adhesive in which the microspheres are embedded.

The present invention further includes a method of forming a plurality of platelets from hemispherically coated and non- coated microspheres. This method is accomplished by embedding a second layer of microspheres onto the hemispherically coated layer of microspheres, and slicing through the two layers to form platelets of coated and non-coated microspheres. The present invention still further includes a method for making a reflective substrate from hemispherically coated reflex- reflective microspheres. The method consists of depositing the hemispherically coated reflex-reflective microspheres into an aqueous based composition and combining non-coated microspheres with the coated microspheres. The mixture of microspheres in random orientation, and the aqueous based composition is then applied to a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the steps for producing a hemispherically coated reflex-reflective icrosphere according to the present invention;

FIG. 2 shows a cross sectional view of hemispherically reflective coated microsphere having a spacer member therebetween;

FIG. 3A shows a cross-sectional view of a six microsphere platelet, having hemispherically coated and non-coated microspheres;

FIG. 3B shows a cross-sectional view of a five microsphere platelet, having hemispherically coated and non-coated microspheres;

FIG. 4 shows a cross-sectional view of a plurality of platelets disposed on a substrate;

FIG. 5 shows the steps for producing a reflex-reflective platelet according to the present invention;

FIG. 6A shows alternative steps for producing a reflex- reflective platelet according to the present invention;

FIG. 6B shows further alternative steps for producing a reflex-reflective platelet according to the present invention;

FIG. 7 shows a cross-sectional view of hemispherically reflective coated microspheres disposed on a substrate;

FIG. 8 shows a cross-sectional view of hemispherically reflective coated microspheres having a spacer member therebetween disposed on a substrate;

FIG. 9 shows a cross-sectional view of both hemispherically reflective coated microspheres and non-coated microspheres disposed on a substrate;

FIG. 10 shows the steps for producing a continuous sheet of reflective material according to the present invention; and

FIG. 11 shows alternative steps for producing a continuous sheet of reflective material according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, and particularly FIG. 1, there is shown a process for hemispherically coating microspheres. This process is accomplished by temporarily securing microspheres 10 to a carrier web 12, the process is a continuous reel to reel operation and it is necessary that the carrier web be strong yet flexible, a variety of materials may be used though it has been found that polyester film pre-treated with an adhesion promoting agent is best suited, the suggested film thickness being 35 to 50 microns.

The carrier web 12 (step a) is first coated with a layer of adhesive 14 (step b) in which the microspheres 10 are removably embedded in a position adjacent to the surface 16 of the carrier web 12, the adhesive 14 should be capable of being dissolved at a later stage. It has been found that a medium to low viscosity synthetic resin emulsion, a suspension of a resin based on vinyl acetate in water and stabilized with dextrine, offers good results and is well suited. The adhesive binder 14 may be applied to the carrier web 12 by screen printer, blade, roller, spray or any method that is suited to laying down a specific quantity of adhesive over a defined area. The adhesive binder 14 should be deposited to leave a thickness of approximately 50% of the diameter of the microspheres when the adhesive is dried, and as such the deposit should allow for the evaporation of the water content of the adhesive when the drying process takes place.

The adhesive 14 is applied to the carrier web 12 and while still in a wet condition, the microspheres 10 are deposited over the carrier (step c) . The spheres should be applied over the maximum possible area and should be embedded to approximately half their diameter in the temporary binder 12. The spheres may be distributed over the surface area by cascading, sifter or hopper onto the wet adhesive binder.

The carrier web 12 may then be passed through pressure rollers to ensure that the microspheres 10 are securely embedded in the adhesive and are located adjacent to the carrier web surface 16, the rollers also press any loose spheres into any spaces to ensure the maximum coverage, the aim being to achieve a single monolayer of spheres over the total surface area of the carrier web. Excess spheres may be removed by brushing or suction. The coated carrier web 12 is then passed through an oven or drying facility (not shown) to activate the adhesive binder and to drive off the water content of the adhesive.

It is at this stage that an additional spacer layer 18 can be applied to the exposed portions of the spheres, as shown in FIG. 2. For instance, a transparent clear or coloured layer may be applied to alter the refractive index of the spheres or to offer coloured reflection, or a composition containing magnetizable particles may be applied to assist in the orientation or relocation of the spheres. This would be carried out using similar procedures as when laying down the temporary binder to the carrier web, though the deposit would be controlled to lay down only the minimum amount of spacer material.

As shown in FIG. 1, the coated carrier web 12 is then passed through a region of a high vacuum metallising chamber wherein a layer of reflecting metal 20 is deposited over the exposed hemispheres of the microspheres 10 (step d) . High vacuum vapour deposition procedures are well known and the application methods concerning this process are as normal procedures. A variety of metals and alloys may be deposited depending on the required results, for the purpose of this process aluminum will normally be used. An aluminum vapour deposit of approximately 250 Angstroms will give an optical density of 3.00 and an approximate thickness of one micron, sufficient to provide an opaque deposit with good reflecting properties.

The carrier web 12 is then passed through a bath or vat containing water to dissolve the adhesive binder 14 and release the hemispherically coated spheres 22 (step e) . The removal of hemispherically coated spheres 22 can be assisted by using warm water and a rotating brush, as an alternative the hemispherically coated spheres 22 can be released from the carrier web 12 using steam or sprays. When the adhesive 14 is dissolved and the hemispherically coated spheres 22 released, the spheres will sink to the base of the bath or container 24 (step f) , and will be continually agitated and flushed with the movement of the water 25 as further spheres are being released.

Excess water is pumped or syphoned off when the spheres have settled in the base of the bath or container 24, the removal of the excess water also removes any remaining adhesive binder residue, which will have floated to the surface of the water. A small amount of water should be left in the bath, sufficient to cover the hemispherically coated microspheres, alternatively the wet spheres can be removed to a storage container and immersed in water until required for use. Keeping the hemispherically coated spheres immersed in water offers several advantages in that the spheres remain in a clean condition and free from forming into clusters and groups which would effect the application of the spheres to a substrate, also the drying of the spheres is a costly and time consuming operation which requires specialized facilities. Water should be added to the containers periodically to ensure that the spheres remain immersed in water and in a wet condition.

The required amount of hemispherically coated microspheres may be removed as needed, based on the wet weight and added directly to aqueous based formulations. As an alternative to applying individual spheres to a substrate the microspheres can be formed into platelets 32, as shown in FIGS. 3A and 3B. As used herein "platelet" shall mean aggregations of two or more microspheres, wherein (i) some of the microspheres are hemispherically coated 22 and some are uncoated 30; and (ii) all of said microspheres in the aggregation are substantially permanently adhered 60 to one other microsphere of the aggregation. Platelets, in one embodiment as shown in FIG. 3A, having six or more microspheres, have such microspheres arrayed in two distinct layers; the first layer consisting of hemispherically coated microspheres 22, and the second layer consisting of non-coated microspheres 30. It is preferred that platelets be arranged no more than two layers thick.

Platelets may be made up from a mix of either the same or different refractive index types. As shown in FIG. 4, the platelets 32 would be used in formulations 26 applied to a substrate 28 that are required to be reflective in all weather conditions. For instance, such materials may be used in the manufacture of life-jackets, life-rafts and the like or liquid coatings applied to exterior surfaces and road marking systems. The platelets can be produced using various combinations of sphere types, say 1.5, 1.92 and 2.2, it is not necessary to hemispherically coat all the spheres in the platelets 32 as a number of coated spheres 22 will be adjacent to the uncoated spheres 30 and as such will provide adequate reflection and the combination of different refractive index types will compensate for the sphere platelets being covered with water and also provide spacer gaps 34 between say a 1.5 refractive index sphere and a reflecting surface which should be approximately 20% of the diameter of the sphere.

As shown in FIG. 5, the platelets 32 (FIGS. 3A and 3B) may be produced by embedding microspheres 10 to a carrier web 12, the process is a continuous reel to reel operation and it is necessary that the carrier web be strong yet flexible. A variety of materials may be used though it has been found that polyester film pre-treated with an adhesion promoting agent is best suited, the suggested film thickness being 35 to 50 microns.

The adhesive 14 is applied to the carrier web 12 and while still in a wet condition, the microspheres 10 are deposited over the carrier (step c) . The spheres should be applied over the maximum possible area and should be embedded to approximately half their diameter in the temporary binder 12. The microspheres 10 may be distributed over the surface area by cascading, sifter or hopper onto the wet adhesive binder.

The coated carrier web 12 is then passed through a region of a high vacuum metallising chamber wherein a layer of reflecting metal 20 is deposited over the exposed hemispheres of the microspheres 10 (step d) . High vacuum vapour deposition procedures are well known and the application methods concerning this process are as normal procedures. A variety of metals and alloys may be deposited depending on the required results, for the purpose of this process aluminum will normally be used. An aluminum vapour deposit of approximately 250 Angstroms will give an optical density of 3.00 and an approximate thickness of one micron, sufficient to provide an opaque deposit with good reflecting properties.

The reflective material layer 20 is then coated with a second, permanent adhesive layer 52 (step e) . Hemispherically coated spheres 22 are embedded to approximately half their diameter in the second, permanent adhesive layer 52. A plurality of second microspheres 54 are deposited over the second, permanent adhesive layer 52 (step f) . The second microspheres 54 should be applied over the maximum possible area and should be embedded to approximately half their diameter in the adhesive layer 52. The spheres may be distributed over the surface area by cascading, sifter or hopper onto the wet adhesive binder.

The carrier web 12 may then be passed through pressure rollers to ensure that the second microspheres 54 are securely embedded in the adhesive 52 and are located in contact with the hemispherically coated microspheres 22.

The second microspheres 54 are positioned so that one hemisphere of each of the second microspheres are embedded within the permanent adhesive 52, and the remaining portion of the second microspheres 54 remain exposed from the second adhesive layer 52.

The carrier 12 is then passed through a water bath to dissolve the temporary adhesive 14 (step g) . Once the hemispherically coated microspheres 22 are removed from the temporary adhesive 14, the hemispherically reflective coated portions 56 of the coated microspheres 22 are embedded within the second adhesive layer 52, while the remaining portion 58 of the coated microspheres 22 remain exposed from both the temporary adhesive 14 and the second, permanent adhesive layer 52.

The first layer containing the hemispherically coated microspheres are then continuously sliced through to the second layer containing the second microspheres to form one or more platelets which are comprised of both hemispherically coated microspheres 22 and second uncoated microspheres 30, as shown in FIGS. 3A and 3B.

In an alternative embodiment, as shown in FIG. 6A, the platelets 32 may be produced by mixing the required amounts of each of the sphere types 72 into an adhesive formulation 78 (step a) , which is then screen printed using a mesh 74 (step b) of a suitable opening size (not shown to scale) and in the required pattern, say small dots or similar, on to a continuous carrier web 12 which has been coated with a temporary adhesive binder 14 and dried (step c) . The carrier web 12 is then passed through a drying facility to activate the adhesive formula and then through a container or bath of water to dissolve the temporary binder and release the platelets (step d) . The platelets 32 may then be included in various formulations for application to the required substrate.

A further alternative, as shown in FIG. 6B is to use a combination of spheres of different refractive index types in an uncoated form 76 (step a) , the spheres are incorporated into a transparent adhesive formulation 78 and screen printed 74 (step b) (not shown to scale) onto a carrier web 12 pre-coated with a temporary adhesive binder 14 and dried, the carrier is then passed through a high vacuum metallising chamber where a layer of reflecting metal 20 is deposited over the platelets (step c) . The carrier web is then passed through a bath containing water and the temporary adhesive is dissolved and the platelets 32 released (step d) , to leave platelets with a reflecting layer over one or more surfaces, which may then be included into various formulations for application to the required substrates. The formulations may include individual spheres as well as other platelets therein.

As shown in FIG 7, aqueous based formulations 26 are well suited to the application of the spheres to various substrates 28, particularly textiles, both natural and synthetic fabrics. Aqueous based print pastes and the like readily accept the inclusion of pigment particles and as such the microspheres may be incorporated with pigment particles or replace the pigment. A formulation may include hemispherically coated spheres 22, FIG. 7, coloured pigment particles 62, FIG. 8, or fluorescent and phosphorescent particles 64 (FIG. 8) , to offer a material that is highly visible during daylight hours and has a glow in the dark effect and also has the ability to reflect light during poor visibility conditions and during the hours of darkness. Included in a basic formula will also be softening, thickening and fixing agents (not shown) in varying amounts depending on the particular substrate.

Aqueous based formulations 26 also offer the advantage of being adaptable to suit most substrates and conditions, agents may be added to ease application such as lubricants and anti¬ blocking agents, decrease or increase curing or storage periods, and the like.

The aqueous based formulations 26 incorporating the microspheres may be applied using a range of methods to different substrates, such as rotary or flat bed screen printers, flat profile or rotary foam applicators, lick rollers, blade coaters or spray may be used utilising conventional application methods, alternatively heat transfer or laminating may be used when suitable. It is important that whichever method is used, the formulations are well mixed prior to application and that the microspheres are evenly distributed throughout the past composition and that any clusters or groups of spheres are broken down.

The amount of microspheres used in a formulation will depend on the intended use of the finished product and the required appearance of the substrate, the amount of spheres used may be between 5% and 75% of the total. A formula to produce an all over design which allows the base substrate colour to be clearly visible under normal lighting conditions may include say, 10% of hemispherically coated spheres, whereas a design which includes a pattern or coloured areas may incorporate say 30% of spheres in the formula. The mix of microspheres in a formula may also vary, say a combination of 1.92 and 1.5 refractive index spheres, or 1.92 and 2.2 refractive index spheres, the particular combination will be determined by the eventual use of the finished product. It is not a necessity that all the spheres in a particular mix are coated over one hemisphere. As shown in FIG. 9, combinations of hemispherically coated 22 and uncoated spheres 30 may be used to achieve particular results. For example, when it is necessary to pick up a background of the surface of the substrate 66, or surrounding colour of the aqueous based formulation, a combination of say 1.92 spheres 68, and 1.5 spheres 70 are used, the 1.5 refractive index spheres would remain uncoated and take up approximately 30% of the total sphere content of a mix. The hemispherically coated 1.92 refractive index spheres will provide optimum light reflectivity and the uncoated 1.5 spheres will offer limited reflection but take up the background or surrounding colour. A combination of hemispherically coated and uncoated 1.92 refractive index spheres will offer light reflectivity while allowing the substrate colour to show and as such reduce any possible speckled effect, the combination of say 1.92 and 2.2 refractive index hemispherically coated spheres is particularly effective when the substrate or finished product may be covered or partially covered with a layer of water, such as during inclement weather conditions. Alternatively only one individual type of refractive index sphere may be used, usually 1.92 spheres for most conventional textile coatings, though the particular refractive index type of sphere used will depend on the intended use of the end product.

As shown in FIG. 10, an additional invention includes applying uncoated microspheres 10 of one or more refractive index types to a carrier web 12. The carrier web 12 (step a) is coated with a temporary adhesive 14 (step b) , the microspheres 10 are then distributed over the maximum area of the carrier and embedded to approximately half their diameter in the adhesive 14 (step c) while the adhesive 14 is in a set condition. The carrier web 12 is then passed through a vacuum chamber and the exposed hemispheres 36 of the microspheres 10 are coated with a metal reflecting surface 20 (step d) using conventional high vacuum vapour deposition procedures. An adhesive coating 38 is then applied to the metallised surface 20 (step e) followed by a substrate 40 (step f) the substrate 40 may be a backing sheet or a fabric, synthetic or natural, acetate, or the like. The particular adhesive and substrate applied will depend on the intended use of the finished product. The coated carrier is then passed through a drying facility to activate the adhesive 14 and secure the substrate 40 to the metallised surface area 20 (not shown) . The carrier 12 is then passed through a water bath to dissolve the temporary binder and release the microsphere coated substrate (step g) . An additional coating 42 of say fluorocarbon or the like, may then be applied to the exposed hemispheres 44 of the microspheres to provide a water and stain repellent finish (step h) . The reflective substrate may then be used as a whole or cut into sections and used as required.

As shown in FIG. 11, another alternative is to apply the microspheres, either uncoated 30 or hemispherically coated 22 or a mix of both, of the same or differing refractive indexes to a carrier web 12 pre-treated with a temporary adhesive 14, (step a) the spheres being partially embedded in the adhesive 14, the adhesive is then dried. A heat reactivatable adhesive 46 is then applied over the microspheres (step b) and a substrate 48 is applied (step c) . The substrate 48 may be a backing sheet or a fabric, synthetic or natural, acetate, or the like. The carrier 12 is then passed through a water bath to dissolve the temporary binder and release the coated spheres retained on the sheet (step d) . A protecting sheet 50 may then be applied to the exposed microsphere area (step e) , the substrate 48 or the protecting sheet 50 may be removed prior to use and the reflective materials applied to a fabric material or any surface by reactivating the adhesive layer 46 using conventional heat transfer methods. The microspheres may be applied to the coated carrier web either as an all over distribution or as a pattern or only in specific designs.

The following is a specific example of the process. A polyester film pre-treated with an adhesion promoting agent and of 50 micron thickness is coated with a layer of adhesive binder, this adhesive being a means of temporarily securing the spheres in position while the next phase of the process takes place. The adhesive being a synthetic resin emulsion, a fine suspension in water of a resin based on vinyl acetate stabilized with dextrine and coated over the surface of the polyester film to a thickness of approximately 35 microns to allow for the evaporation of the water content during the drying process. While the binder is in a wet condition, microspheres with an average size of 40 microns diameter and with a refractive index of 1.92 are deposited over the entire surface area of the carrier web, the spheres being pressed into the binder and adjacent to the surface of the polyester film excess spheres are then removed by brushing and the coated carrier web travels through a hot air oven set at a moderate temperature to activate the adhesive and drive off the water content, leaving the microspheres securely fixed in the binder to approximately half their diameter. The coated carrier web is then passed through a high vacuum metallising chamber wherein a layer of aluminum is applied to the exposed hemispheres of the microspheres using conventional high vacuum vapour deposition procedures, the light reflecting aluminum layer being deposited at approximately 250 Angstroms which equates to approximately one micron in thickness. The coated carrier web is then passed through a bath containing warm water, a soft brush is used to assist the release of the spheres as the adhesive binder is dissolved. The hemispherically coasted spheres then sink to the bottom of the bath and are continually washed through the agitation of the water as further spheres are removed. The hemispherically coated microspheres are then removed and placed in a container and a sufficient quantity of water is placed in the container to completely cover the spheres, the spheres remain immersed in the water until required for use.

A formula is then made up of the following components, the ingredients being added to water in the following amounts and in the following order while being continuously stirred and agitated, preferably by a mechanical mixer to ensure an even distribution throughout the mix.

Water 44%

Aqueous Emulsion of an Acrylic Copolymer 20%

Methylol Melamine Ether compound in water 2% Aqueous Emulsion of a Polymeric Plasticiser and a Silicone Oil 1% Copolymer of Acrylamide/Ammonium Acrylate dispersed in a Medicinal Mineral Oil 2%

Hemispherically Coated Microspheres 30%

Synthetic Concentrated Colour Pigment 1%

The formula is applied to a polyester/cotton fabric using conventional flat bed print methods and a screen mesh of 43T to allow the hemispherically coated spheres to pass through the openings without blocking. The coated fabric is then hot air dried at 180°c for 3 minutes.

In a second example, microspheres are prepared and hemispherically coated as in the first example and stored in water ready for use. A formula is then made up of the following quantities and in the following order, added to water while being continuously stirred:

Water 60%

Aqueous Emulsion of an Acrylic Copolymer 18%

Methylol Melamine Ether compound in water 2%

Aqueous Emulsion of a Polymeric Plasticiser and a Silicone Oil 2%

Copolymer of Acrylamide/Ammonium Acrylate dispersed in a Medicinal Mineral Oil 2% Hemispherically Coated Microspheres 12%

Synthetic Concentrated Colour Pigment (Fluorescent Yellow) 4%

The formula is applied to an undyed polyester/cotton fabric using conventional rotary screen printing facilities and methods using an open mesh 40s screen, to give an all-over blotch print. The fabric is then passed through a drying facility set at 150°c for approximately 4 minutes. The fabric is then subjected to a fluorocarbon formulation to provide a stain and water repellent finish, using standard methods.

It is to be understood that the present invention is by no means limited to the particular construction herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.

Having thus described the invention, what is claimed as new and desire to secure by Letters Patent of the United States is:

Claims

1. A method for producing hemispherically coated reflex- reflective microspheres for slurry application to a substrate, the steps comprising:

(a) coating a carrier web with a first adhesive layer;

(b) removably embedding a plurality of microspheres into said first adhesive layer, so that one hemisphere of each of said microspheres is embedded therein, the remaining portion of said microspheres remaining exposed from said first adhesive layer;

(c) applying a reflective material layer to said exposed hemispherical portion of said microspheres, causing them to be reflex-reflective microspheres;

(d) removing said microspheres from said first adhesive layer; and,

(e) maintaining said microspheres in water for slurry application.

2. The method according to claim 1, wherein the step of removably embedding a plurality of microspheres further comprises the step of applying a spacer layer to the exposed hemispherical portions of said microspheres.

3. The method according to claim 2, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a colored layer.

4. The method according to claim 2, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a transparent clear layer.

5. The method according to claim 2, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a magnetizable composition layer.

6. The method according to claim 1 wherein said step of removing said microspheres is accomplished by dissolving said first adhesive layer in water.

7. The method according to claim 1, wherein said microspheres are comprised of microspheres of varying refractive indexes.

8. A method for producing a retro-reflective sheeting, the steps comprising:

(a) coating a carrier web with a first adhesive layer;

(b) removably embedding a plurality of microspheres into said first adhesive layer, so that one hemisphere of each of said microspheres is embedded therein, the remaining portion of the microspheres remaining exposed from said first adhesive layer;

(c) applying a reflective material layer to the exposed hemispherical portion of said microspheres, causing them to be reflex-reflective microspheres;

(d) coating the reflective material layer with a second adhesive layer, so that the hemispherically reflective coated portions of said microspheres are embedded therein;

(e) adhering a substrate to said second adhesive layer, to form said retro-reflective sheeting; and, (f) removing the hemispherically reflective coated microspheres from said first adhesive layer, so that the hemispherically reflective coated portions of said microspheres are embedded within said second adhesive layer, the remaining portion of the microspheres remaining exposed from said first adhesive layer and said second adhesive layer.

9. The method according to claim 8, wherein the step of removably embedding further comprises the step of applying a spacer layer to the exposed hemispherical portions of said microspheres.

10. The method according to claim 9, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a colored layer.

11. The method according to claim 9, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a transparent clear layer.

12. The method according to claim 9, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a magnetizable composition layer.

13. The method according to claim 8, in which said substrate is a backing sheet.

14. The method according to claim 13, in which a top surface of said substrate is a thermally reactivatable adhesive.

15. The method according to claim 13, in which a top surface of said substrate is pressure sensitive adhesive.

16. The method according to claim 8, in which said substrate is a material layer, and said second adhesive layer is bonded thereto.

17. The method according to claim 8, further comprising the steps of:

(i) removing said substrate from said second adhesive layer; and

(ii) transferring said second adhesive layer to a material layer in place of said substrate.

18. The method according to claim 8 wherein said step of removing said microspheres is accomplished by dissolving said first adhesive layer in water.

19. The method according to claim 8, wherein said microspheres are comprised of microspheres of varying refractive indexes.

20. A microsphere platelet.

21. A platelet according to claim 20, wherein the microspheres of said platelet are comprised of hemispherically reflective coated microspheres and non-coated microspheres.

22. A platelet according to claim 20, wherein the microspheres of said platelet are comprised of microspheres with varying refractive indexes.

23. A method for producing a reflex-reflective platelet for slurry application to a substrate, the steps comprising:

(a) coating a carrier web with a first adhesive layer;

(b) removably embedding a plurality of first microspheres into said first adhesive layer, so that one hemisphere of each of said first microspheres is embedded therein, the remaining portion of said first microspheres remaining exposed from said first adhesive layer;

(c) applying a reflective material layer to the exposed hemispherical portion of said first microspheres, causing them to be reflex-reflective microspheres;

(d) coating the reflective material layer with a second adhesive layer, so that the hemispherically reflective coated portions of said first microspheres are embedded therein;

(e) embedding a plurality of second microspheres into said second adhesive layer, so that one hemisphere of each of said second microspheres are embedded therein, the remaining portion of the second microspheres remaining exposed from said second adhesive layer;

(f) removing said hemispherically reflective coated first microspheres from said first adhesive layer, so that the hemispherically reflective coated portions of said first microspheres are embedded within said second adhesive layer, the remaining portion of said first microspheres remaining exposed from said first adhesive layer and said second adhesive layer; and,

(g) slicing continuously through from a first layer containing said first microspheres to through a second layer containing said second microspheres to form a plurality of platelets comprised of both first microspheres and second microspheres.

24. The method according to claim 23, wherein the step of removably embedding a plurality of microspheres further comprises the step of applying a spacer layer to the exposed hemispherical portions of said microspheres.

25. The method according to claim 24, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a colored layer.

26. The method according to claim 24, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a transparent clear layer.

27. The method according to claim 24, in which said spacer layer applied to the exposed hemispherical portions of said microspheres is a magnetizable composition layer.

28. The method according to claim 23, wherein said step of removing said microspheres is accomplished by dissolving said first adhesive layer in water.

29. The method according to claim 23, wherein said step of embedding a plurality of second microspheres into said second adhesive layer comprises positioning the bottom portion of said second microspheres in said second adhesive layer in contact with a top portion of second first microspheres coated with said reflective material layer.

30. The method according to claim 23, wherein said step of embedding a plurality of second microspheres into said second adhesive layer comprises positioning said second microspheres apart from other second microspheres.

31. The method according to claim 23, wherein said first microspheres and said second microspheres are each comprised of microspheres of varying refractive indexes.

32. A method for producing a reflex-reflective platelet for slurry application to a substrate, the steps comprising:

(a) creating an adhesive-based microspheric composition;

(b) passing said adhesive-based microspheric composition through a printing screen onto an adhesive layer of a carrier web having an adhesive layer;

(c) partially embedding said microspheres in the adhesive; and,

(d) removing said platelets from said adhesive layer.

33. The method according to claim 32, in which said adhesive- based microspheric composition is comprised of hemispherically reflective coated microspheres and non-coated microspheres.

34. The method according to claim 32, in which said step of partially embedding said microspheres further comprises the step of applying a reflective material layer to portions of said microspheres exposed from said adhesive layer.

35. A method for making a reflective substrate from hemispherically coated reflex-reflective microspheres in a slurry, the steps comprising:

(a) depositing the hemispherically coated reflex-reflective microspheres into an aqueous based composition;

(b) combining, in the aqueous based composition, non-coated microspheres with said coated microspheres; and,

(c) applying the mixture of microspheres in random orientation, and said aqueous based composition, to a substrate.

36. The method according to claim 35, wherein said microspheres are comprised of microspheres of varying refractive indexes.

37. The method according to claim 35, further comprising the step of depositing microsphere platelets into the aqueous based composition.

38. The method according to claim 37, wherein the microspheres of said platelets are comprised of microspheres of varying refractive indexes.

39. The method according to claim 35, further comprising the step of depositing a pigment into said composition.

40. The method according to claim 39, in which said pigment is a colored stain.

41. The method according to claim 39, in which said pigment is a phosphorescent stain.