US3773535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Abrasion resistant stabilized lead chromate pigments coated with silica and polyolefin wax
Assignee: Vibrantz Corp
•
Filing: 1972-02-25
•
Granted: 1973-11-20
•
Expires: 1992-02-25
Abstract
Abstract Lead chromate pigments are improved by coating the pigment particles with a layer of silica and then encapsulating the silica coated particles in polyolefin wax. Such pigments when used in thermoplastic molding compositions exhibit good abrasion resistance and color stability even at elevated temperatures required for compounding and molding of the thermoplastics.
Inventors
- 👤 A Burgyan
- 👤 R Pipoly
- 👤 P Stelzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:36
CPC Classifications
C; C09; C09C; C09C3/00; C09C3/006; C09C3/06; C09C3/063; C09C3/10; C01; C01P; C01P2004/00; C01P2004/80; C01P2004/82; C01P2004/84; C01P2006/00; C01P2006/60
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
94 words
A lead chromate pigment having good abrasion resistance and color stability suitable for use in coloring of thermoplastic resins consisting essentially of (a) individual lead chromate pigment particles, (b) a surface coating of silica upon each of said particles in an amount between about five to 50 percent of the total combined weight of pigment and silica and (c) a layer of polyolefin wax on each of said particles encapsulating the silica coated particles, said polyolefin wax amounting to between about 10 to 70 percent of the total weight of pigment, silica and wax.
Claim 2
Dependent Claim
21 words
The pigment of claim 2 wherein the pigment particles are at least small enough to pass a 40 mesh standard screen.
Claim 3
Dependent Claim
39 words
The method of claim 1 wherein said encapsulation step 2 is accomplished by homogeneously mixing together the silica coated pigment of step 1 with molten polyolefin wax, cooling the resulting mix to a solid mass and pulverizing the mass.
Claim 4
Dependent Claim
69 words
The method of claim 1 wherein said encapsulation step 2 is accomplished by forming a slurry in water of the silica coated pigment of step 1, mixing an emulsion of polyolefin wax in water with said slurry, acidifying the emulsion and slurry mixture to coagulate the emulsion, separating the suspended solids of the acidified mixture by filtration from the liquid phase, washing the filtered solids and then drying them.
Claim 5
Dependent Claim
66 words
The method of claim 1 wherein said silica deposition step 1, is accomplished by simultaneously mixing together an aqueous slurry of lead chromate pigment, an aqueous solution of sodium silicate and an aqueous acid solution containing sufficient hydrogen ions to convert the sodium silicate into silica whereby silica is uniformly precipitated upon the pigment particles and then separating the solids from the resulting slurry by filtration.
Claim 6
Dependent Claim
16 words
The method of claim 6 wherein said acid solution consists of sulfuric acid dissolved in water.
Claim 7
Dependent Claim
48 words
The method of claim 6 wherein said simultaneous mixing is preformed by adding streamwise the aqueous sodium silicate solution and the acid solution to the aqueous slurry of lead chromate pigment while the slurry is continuously stirred and heated to a temperature between about 60* and 100* C.
Claim 8
Dependent Claim
36 words
The method of claim 8 wherein the resulting mixture is filtered after the completion of said streamwise additions, the filtercake is washed, air dried, further dried by heating to between about 70*-90* C and then pulverized.
Claim 9
Independent Claim
114 words
A method for manufacture of lead chromate pigments having good abrasion resistance and color stability which comprises (1) depositing on the pigment particles a coating of silica that amounts to between about five to 50 percent of the total combined weight of pigment and silica, (2) encapsulating the silica coated pigment particles with polyolefin wax so the amount of wax is between 10 to 70 percent of the total weight of the product by vapor deposition of polyolefin wax upon the individual silica coated pigment particles obtained in step (1), and (3) recovering lead chromate pigment in the form of individual particles each having a coating of said polyolefin wax overlaying said silica coating.
Claim 10
Independent Claim
128 words
A method for manufacture of lead chromate pigments having good abrasion resistance and color stability which comprises (1) depositing on the pigment particles a coating of silica that amounts to between about five to 50 percent of the total combined weight of pigment and silica, (2) encapsulating the silica coated pigment particles with polyolefin wax so the amount of wax is between 10 to 70 percent of the total weight of the product by mixing together the silica coated pigment particles of step (1) with a solution of polyolefin wax in an organic solvent followed by evaporation of the solvent from the resulting slurry, and (3) recovering lead chromate pigment in the form of individual particles each having a coating of said polyolefin wax overlaying said silica coating.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |