Pre-printed latent image spirit duplicating masters
AssigneeThe Mazer Corporation
InventorIrving Panken
Life of this patent
Estimating the term…
Abstract
A pre-printed spirit duplicating master containing visible imaged material and latent imaged material for use in preparing copies for self-instructional examination or work assignments. The latent images on the copy sheet are capable of being revealed with a pen containing a chemical developer and this can be done by the student in self-examination. The use of the pre-printed masters frees the teacher from the chore of preparing exams, or work assignments, making the masters, and from grading the papers.
Claims18
A pre-printed spirit duplicating master comprising a sheet having reverse printed on the backside thereof by means of a printing technique selected from the group consisting of offset, rotogravure, letterpress, stencilling, or aniline printing, a visible image spirit duplicating ink in one area and a latent image spirit duplicating ink in another area, both said visible and latent inks, when contacted with an alcohol or spirit wetted copy paper, being capable of transfer to said copy paper to impart corresponding visible and latent images thereon, said corresponding latent image being capable of development into a second visible image by application of a color developer thereto, said latent image spirit duplicating ink containing a color former selected from the group consisting of dithiooxamide and derivatives thereof and a carrier vehicle therefor, said latent image ink being resistant to changes in temperature and humidity, capable of producing at least 100 acceptable copies and capable of making copies with little or no loss of intensity in the developed image after being stored for a period of at least up to 1 year.
A pre-printed spirit duplicating master having an image printed on the front side and reverse printed by means of a printing technique selected from the group consisting of offset, rotogravure, letterpress, stencilling or aniline printing on the back side a visible image spirit duplicating ink and in another area latent image spirit duplicating ink comprising by weight 20-27% stearate resin, 8-17% fatty acid, 8-10% mineral oil, 2-4% petroleum jelly, 0-1% wetting agent, 0-1% ultraviolet absorber, and 44-54% of a dithiooxamide derivative color former.
In a spirit duplicating process wherein multiple copies are prepared by contacting a master with copy paper wetted lightly with an alcohol or spirit capable of dissolving some of the ink of said master whereby ink is transferred from said master to the copy paper, the improvement comprising:
- contacting said wetted copy paper with a preprinted master having reverse printed on the side thereof which contacts the copy paper, a visible image spirit duplicating ink in one area and a latent image spirit duplicating ink in another area, said latent image ink containing a color former selected from the group consisting of dithiooxamide and derivatives thereof and a carrier vehicle therefor, transferring said inks to said copy paper and forming on said copy paper a positive visible image and a positive latent image, said positive latent image containing said color former selected from the group consisting of dithiooxamide and derivatives thereof and being capable of development into a visible image by application of a color developer thereto.
Dependencies are inferred from the claim text.