Primer layers having improved reflectivity and thermal insulation properties are provided for use in microencapsulated thermal imaging sheets. Primer layers having a polymeric binder, of about 3% to about 60% by weight, relative to the total weight of the primer layer, of a white particulate, a primer substrate, and hollow particulate particles improve the reflectivity, color development, color density, and thermal insulation of microcapsule imaging sheets including the same. A black back-coat applied to the substrate on a side opposite the primer layer further enhances the Dmax and E.sub.10 of microcapsule imaging sheets and prevents premature exposure of microcapsule imaging sheets in stacked media.

Provided are thermochromic color-memorizing composition and thermochromic color-memorizing microcapsule pigment encapsulating the same, the thermochromic color-memorizing composition including: (a) an electron-donating color-developing organic compound; (b) an electron-accepting compound; and (c) an ester compound represented by the following formula (1) as a reaction medium which controls color reaction between the components (a) and (b): ##STR00001##

Reversible thermochromic and photochromic ink compositions and markers, pens or writing instruments that use them are herein disclosed.

A microencapsulation process is improved by adding a stabilizing agent that contains one or more catalytic organo-metal oxide materials, such as metal soaps. This functions as a crosslinker by causing unsaturated bonds in the microcapsule walls to react, thereby stabilizing the microcapsules against the effects of additives to coatings that, otherwise, degrade the functionality of thermochromic or photochromic materials at the microcapsule core.

Color change compositions that transition from a first to second color state upon application of an applied stimulus are provided. Also provided are substrates having the compositions on a surface thereof, as well as methods of making and using the compositions.

An image erasing apparatus according to an embodiment includes a scanner that reads an image printed on a sheet with decolorable colorant, the image including a first owner information. A decoloring unit decolors the image printed on the sheet. An input device receives a second owner information. A controller identifies the first owner information included in the image read by the scanner, and determines whether the first owner information corresponds to the second owner information. Based on the determination, the controller selectively controls the decoloring unit to decolor the image.

A microencapsulated pigment including a leuco dye system is incorporated as one or more layers in a roll of adhesive tape. The tape is applied and may be rubbed by hand or another object to induce a color change. The change may serve as an indicator that the tape is well adhered for masking purposes in a painting operation, or to present a design where only selected portions of the tape are rubbed to induce the color change. The microencapsulated pigment may be constructed so that the color change is irreversible or reversible.

A microencapsulation process is improved by adding a stabilizing agent that contains one or more catalytic organo-metal oxide materials, such as metal soaps. This functions as a crosslinker by causing unsaturated bonds in the microcapsule walls to react, thereby stabilizing the microcapsules against the effects of additives to coatings that, otherwise, degrade the functionality of thermochromic or photochromic materials at the microcapsule core.

A method is provided for making thermochromic pigments in microcapsules having unusually small particle sizes.

Reversible thermochromic and photochromic ink compositions and markers, pens or writing instruments that use them are herein disclosed.