Claims
- 1. A pigment material for use in a coating composition suitable for coating a sheet material to be printed by an electrophotographic printer which pigment material comprises a blend of Components A and B as follows:Component A: a fine pigment material suitable for gloss coating of a sheet material the pigment material comprising particles at least 80% by weight of which have an equivalent spherical diameter (“esd”) of less than 2 μm and having a particle size distribution (“psd”) such that its d50 value, namely the particle esd value less than which 50% of the particles have an esd, is less than 1 μm; and Component B: a coarse pigment material having a psd such that its d50 value is from 2 μm to 10 μm and such that not more than 2% by weight of the particles of the coarse pigment material have an esd greater than 15 μm; wherein the weight ratio of Component A to Component B is at least 4:1.
- 2. A pigment material as claimed in claim 1 and wherein the weight ratio of Component A to Component B is in the range 4:1 to 100:1.
- 3. A pigment material as claimed in claim 1 and wherein Component A has a d50 value of from 0.4 μm to 0.7 μm.
- 4. A pigment material as claimed in claim 1 and wherein not more than 2% by weight of the particles of Component A have an esd of 5 μm or more.
- 5. A pigment material as claimed in claim 1 and wherein Component A has on a log-normal particle size increment histogram, a histogram peak which at half peak maximum height has a width of from 1.0 to 1.2 along the esd logarithmic scale.
- 6. A pigment material as claimed in claim 1 and wherein Component A and Component B each independently comprises one or more of calcium carbonate, calcined kaolin, hydrous kaolin, talc, mica, dolomite, silica, zeolite, satin white, titania, calcium sulphate or plastic pigment.
- 7. An aqueous coating composition suitable for coating a sheet material to be printed by an electrophotographic printer which comprises a pigment material according to claim 1 together with a hydrophilic adhesive.
- 8. A pigment material as claimed in claim 6 and wherein at least one of Component A or Component B comprises gypsum.
Parent Case Info
This application claims priority from U.S. Provisional Application No. 60/093,201, filed Jul. 17, 1998.
US Referenced Citations (8)
Provisional Applications (1)
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Number |
Date |
Country |
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60/093201 |
Jul 1998 |
US |