Record sheets sensitized with reduced charge montmorillonite pigment

Paper coated with finely divided particles of mixed layer smectite, the lattice of which is partially dioctahedral montmorillonite and partially trioctahedral such as saponite or hectorite, and wherein the proportion of trioctahedral is small, the negative charge of the dioctahedral portion of said smectite having been reduced by ion-exchange with lithium ions and the structure having been irreversibly collapsed by heat treatment.

Paper coated with finely divided particles of mixed layer smectite, the lattice of which is partially dioctahedral montmorillonite and partially trioctahedral such as saponite or hectorite, and wherein the proportion of trioctahedral is small, said mixed layer smectite having been ion-exchanged with from about 60 to 120 meq./100 g. of lithium ions and heated at a temperature in the range of about 160.degree. to 300.degree. C. to collapse irreversibly the dioctahedral montmorillonite structure, said coated paper being capable of producing a stable intense blue color when contacted with a solution of crystal violet lactone in an organic solvent.

A method for preparing a sensitized image-developing substrate for a record material system which comprises:

• partially exchanging exchangeable cations in a mixed layer smectite, the lattice of which is partially dioctahedral montmorillonite and partially trioctahedral such as saponite or hectorite, and wherein the proportion of trioctahedral is small, said mixed layer smectite having been ion-exchanged with lithium ions, then heated at a temperature in the range of about 160.degree. to 300.degree. C. to collapse irreversibly the dioctahedral montmorillonite structure and then ground until the particles are finer than 15 microns;
• mixing the ground material with water and a paper coating binder to form a paper coating composition;
• and applying said paper coating composition on a paper web.

A pressure-sensitive record system comprising transfer members coated with an encapsulated solution of at least one basic colorless or substantially colorless color-forming dye precursor compound and image-developing members coated uniformly throughout a recording area thereof with a multiplicity of fluid energy milled particles of mixed layer smectite, the lattice of which is partially dioctahedral montmorillonite and partially trioctahedral such as saponite or hectorite, and wherein the proportion of trioctahedral is small, said mixed layer smectite having been subjected to ion-exchange treatment with lithium ions followed by heat treatment to collapse irreversibly dioctahedral montmorillonite structure.

A pressure-sensitive record system comprising transfer sheets coated with an encapsulated solution of crystal violet lactone, crystal violet lactone being the sole chromogen in said record system, and image-receiving sheets coated uniformly throughout a recording area thereof with a paper coating adhesive and particles of a reactive pigment obtained from mixed layer smectite, the lattice of which is partially dioctahedral montmorillonite and partially trioctahedral such as saponite or hectorite, and wherein the proportion of trioctahedral is small, said mixed layer smectite having been ion exchanged with from about 60 to 120 meq./100 g. of lithium ions, said clay material containing no more than about 7% hydrated silica, heating the clay thus treated at a temperature in the range of 160.degree. to 250.degree. C. until the structure of the dioctahedral montmorillonite is collapsed, as evidenced by the fact that the product has a basal planar spacing in the range of about 9.4 to 10.7A., said particles of reactive pigment being essentially all finer than 15 microns and predominantly in the size range of 1/2 to 5 microns.