Low refractive index glass microsphere coated article having a smooth surface and a method for preparing same

A transfer article comprising:

• (a) a transfer carrier, the transfer carrier comprising:
• (i) a support layer;
• and
• (ii) a thermoplastic glass bead release layer bonded to the support layer;
• (b) a layer of a mixture of transparent glass beads and irregularly shaped glass particles, the mixture optionally treated with an adhesion promoter, formed on a side of the thermoplastic glass bead release layer opposite the support layer, such that the glass beads are embedded to between about 20% and about 70% of their average diameter in the thermoplastic glass bead release layer and at least some of the irregularly shaped glass particles are partially embedded in the thermoplastic glass bead release layer and some of the irregularly shaped glass particles are optionally, completely embedded in the thermoplastic glass bead release layer,
• wherein at least 95% by weight of the total number of glass beads and irregularly shaped glass particles fall within a threefold range such that the smallest and largest cross-sectional diameters differ by a factor of about 3 or less;
• wherein the average cross-sectional diameter of the mixture of the glass beads and the irregularly shaped glass particles, for at least 95 percent by weight of the mixture ranges from about 20 microns to about 180 microns;
• wherein the glass beads and irregularly shaped glass particles have refractive indices of about 1.5 to about 1.6;
• (c) a layer of a first adhesive, capable of adhering to the layer of the mixture of the glass beads and the irregularly shaped glass particles, the mixture optionally treated with an adhesion promoter;
• wherein the first adhesive layer is formed on the surfaces of the glass beads and irregularly shaped glass particles not embedded in the thermoplastic glass bead release layer such that the glass beads are embedded to between about 30% to about 80% of their average diameter in the first adhesive layer;
• wherein the adhesion of the first adhesive to the glass beads is stronger than the adhesion of the thermoplastic release layer to the glass beads, wherein the aforesaid average count of irregularly shaped glass particles is based on irregularly shaped glass particles having a cross-sectional diameter equal to or greater than the smallest cross-sectional diameter in the threefold range;
• wherein the transfer articles comprise at least about 3% irregularly shaped glass particles by average count per unit area of the transfer article based upon the total count of the glass beads plus the irregularly shaped glass particles per unit area of the transfer article;
• wherein the glass beads and irregularly shaped glass particles are positioned such that upon removal of the transfer carrier from the transfer article the coefficient of friction of a planer surface of the first adhesive layer having a continuous layer of glass beads and irregularly shaped glass particles partially embedded therein is less than about 0.3.

A method of making a transfer article, the method comprising the steps of:

• (a) providing a transfer carrier, the transfer carrier comprising a thermoplastic glass bead release layer bonded to a support layer;
• (b) partially embedding a layer of a mixture of transparent glass beads and irregularly shaped glass particles, the mixture optionally treated with an adhesion promoter such that the glass beads are embedded to between about 20% and about 70% of their average diameter in the thermoplastic glass bead release layer and at least some of the irregularly shaped glass particles are partially embedded in the release layer and some of the irregularly shaped glass particles are optionally, completely embedded in the release layer,
• wherein the average cross-sectional diameter of the mixture of the glass beads and the irregularly shaped glass particles, for at least 95% by weight of the mixture ranges from about 20 microns to about 180 microns;
• wherein at least 95% by weight of the total number of glass beads and irregularly shaped glass particles fall within a threefold range such that the smallest and largest cross-sectional diameters differ by a factor of about 3 or less;
• wherein the transfer article comprises at least about 3% irregularly shaped glass particles by average count per unit area of the transfer article based on the average total count per unit area of the transfer article of the glass beads plus the irregularly shaped glass particles, wherein the aforesaid average count of irregularly shaped glass particles is based on irregularly shaped glass particles having a cross-sectional diameter equal to or greater than the smallest cross-sectional diameter in the threefold range;
• wherein the glass beads and irregularly shaped glass particles have refractive indexes of about 1.5 to about 1.6;
• (c) bonding a layer of a first adhesive layer over the surfaces of the glass beads and irregularly shaped glass particles not embedded in the thermoplastic release layer;
• wherein the adhesion of the first adhesive layer to the glass beads is stronger than the adhesion of the thermoplastic release layer to the glass beads;
• wherein the glass beads and irregularly shaped particles are positioned such that upon removal of the transfer carrier of the transfer article the coefficient of friction of a planer surface of the first adhesive layer having a continuous layer of the mixture of the glass beads and irregularly shaped glass particles partially embedded therein is less than about 0.3.