Latent image printing process and substrate

Claim 2

A printing process comprising the steps of: providing a translucent first sheet member having one surface with a colorless planar first layer of only one of a pair of a color developer and a color former dye in at least one selected latent image area where a latent image is to be formed and in at least one selected visible image area where a visible image is to be formed and a colorless continuous planar second shielding layer over the first layer where the latent image is to be formed and where the visible image is to be formed; removably mounting a second sheet member having an uncoated surface with a background color on the first sheet member with the uncoated surface adjacent the shielding layer in the at least one selected latent image area and coated with the other of the pair in the at least one visible image area, wherein said one of the pair is reactable with the other of the pair to produce a spectral response which is visible relative to the background color of the uncoated and coated surface of the second sheet member and visible through the translucent first sheet member and wherein the shielding layer has a thickness of 0.1 to 10 microns and a melting point of from 50° to 200° C.; and transferring selected portions of the first and second layers to the uncoated and coated surface of the second sheet member corresponding to a desired latent image and a desired visible image respectively by applying heat to one of the first and second sheets members to form the desired latent image on the uncoated surface of the second sheet member which is not visible until activated by the other of the pair carried in a solvent and to form the desired visible image on the coated surface of the second sheet member which is visible through the first sheet member.

Claim 3

The process according to claim 1, wherein the at least one visible image area is along at least one margin of the first and second sheet members.

Claim 4

The process according to claim 1, wherein the first and second sheet members are removably mounted along the edges thereof.

Claim 5

The process according to claim 1, wherein the first and second sheet members are paper sheets.

Claim 6

The process according to claim 1, wherein one of the first and second sheet members has a thickness of about 25 microns.

Claim 7

The process according to claim 1, wherein the shielding layer includes a sensitizer.

Claim 8

The process according to claim 1, further comprising providing a third layer of a sensitizer on the second layer.

Claim 9

The process according to claim 1, further comprising removing the first sheet member from the second sheet member to expose the uncoated surface with the latent image thereon and thereafter activating the latent image to form a visible image by applying the other of said pair carried in the solvent to the uncoated surface.

Claim 10

A latent image printing substrate comprising: a translucent first sheet member having one surface with a colorless planar first layer of only one of a pair of a color developer and a color former dye in at least one selected latent image area where a latent image is to be formed and in at least one selected visible image area where a visible image is to be formed and a colorless continuous planar second shielding layer over the first layer where the latent image is to be formed and where the visible image is to be formed; a second sheet member having a first surface with a background color which is uncoated in at least one selected latent image area and coated with the other of the pair in at least one visible image area and removably mounted on the first sheet member with the first surface adjacent the shielding layer, wherein said one of the pair is reactable with the other of the pair when carried in the solvent to produce a spectral response which is visible relative to the background color of the uncoated and coated first surface of the second sheet member and visible through the translucent first sheet member and wherein the shielding layer has a thickness of 0.1 to 10 microns and a melting point of from 50° to 200° C.; and wherein selected portions of the first and second layers corresponding to a desired latent image and a desired visible image respectively are transferrable to the uncoated and coated first surface of the second sheet member in response to the application of heat to one of the first and second sheets members to form the desired visible image on the coated surface of the second sheet member which is visible through the first sheet member and to form the desired latent image on the uncoated surface of the second sheet member which is not visible until activated by the other of the pair carried in a solvent.

Claim 11

A latent image printing substrate comprising: a translucent first sheet member having one surface with a colorless planar first layer of only one of a pair of a color developer and a color former dye in at least one selected latent image area where a latent image is to be formed and in at least one selected visible image area where a visible image is to be formed and a colorless continuous planar second shielding layer over the first layer where the latent image is to be formed and where the visible image is to be formed; a second sheet member having a first surface with a background color which is uncoated in at least one selected latent image area and coated with the other of the pair in at least one visible image area and removably mounted on the first sheet member with the first surface adjacent the shielding layer, wherein said one of the pair is reactable with the other of the pair when carried in the solvent to produce a spectral response which is visible relative to the background color of the uncoated and coated first surface of the second sheet member and visible through the translucent first sheet member and wherein the shielding layer has a thickness of 0.1 to 10 microns and a melting point of from 50° to 200° C.; and wherein selected portions of the first and second layers corresponding to a desired latent image and a desired visible image respectively are transferrable to the uncoated and coated first surface of the second sheet member in response to the application of heat to one of the first and second sheets members to form the desired visible image on the coated surface of the second sheet member which is visible through the first sheet member and to form the desired latent image on the uncoated surface of the second sheet member which is not visible until activated by the other of the pair carried in a solvent.

Claim 12

The substrate according to claim 9, wherein the at least one visible image area is along at least one margin of the first and second sheet members.

Claim 13

The substrate according to claim 9, wherein the first and second sheet members are removably mounted along the edges thereof.

Claim 14

The substrate according to claim 9, wherein the first and second sheet members are paper sheets.

Claim 15

The substrate according to claim 9, wherein one of the first and second sheet members has a thickness of about 25 microns.

Claim 16

The substrate according to claim 9, wherein the shielding layer includes a sensitizer.

Claim 17

The substrate according to claim 9, further comprising a third layer of a sensitizer on the second layer.