P-xylene vapor phase polymerization coating of electrostatographic particles

Claim 2

A PROCESS FOR COATING ELECTROSTATOGRAPIC CARRIER PARTICLES HAVING AN AVERAGE DIAMETER OF BETWEEN ABOUT 1 MICRON AND ABOUT 1,000 MICRONS WITH A P-XYLENE POLYMERIC MATERIAL COMPRISING THE STEP OF: A. SUBLIMING A CYLIC DI-P-XYLENE DIMER TO FORM A DIMER VAPOR, B. PYROLYZING SAID DIMER VAPOR IN A VACUUM OF BETWEEN ABOUT 0.0001 AND 10.0 MILLIMETERS OF MERCURY TO FORM VAPOROUS P-XYLYLENE DIRADICALS, C. AGIATING A BED IF SAID CARRIER PARTICLES WITHIN A HIGH FREQUENCY VIBRATING CHAMBER, AND D. CONTACTING SAID VAPOUROUS P-XYLYLENE DIRADICALS WITH SAID AGIGATED BED OF CARRIER PARTICLLES AT A TEMPERATURE ABOVE ABOUT 30*C BY DRAWING SAID VACUUM THROUGH SAID AGIGATED BED OF CARRIER PARTICLES THEREBY FORCING SAID VAPOROUS DIRADICALS TO TRAVEL A CIRCUITIOUS PATH DIRECTLY THROUGH SAID AGIGATED BED OF CARRIER PARTICLES WHEREBY SUFFICIENT CONTACT IS EFFECTED BETWEEN SAID CARRIER PARTICLES AND SAID VAPOROUS DIRADICALS TO ALLOW POLYMERIZATION OF SAID DIRADICALS ON SAID CARRIER PARTICLES AT TEMPERATURES ABOVE THE CEILING CONDENSATION TEMPERATURE OF SAID VAPOROUS P-XYLYLENE DIRADICALS.

Claim 3

A process for coating electrostatographic carrier particles in accordance with claim 1 wherein said bed of carrier particles is maintained within said vibrating chamber at a level above the vacuum exhaust parts of said chamber to insure that said vaporous diradicals travel said circuitous path through said bed of said carrier particles.

Claim 4

A process for coating electrostatographic carrier particles in accordance with claim 1 wherein said carrier particles are at a temperature above about 40*C and said cyclic di-p-xylylene is unsubstituted di-p-xylylene.

Claim 5

A process for coating electrostatographic carrier particles in accordance with claim 1 wherein said carrier particles are metallic carrier beads having an average diameter between about 50 and 600 microns.

Claim 6

A process for coating electrostatographic carrier particles in accordance with claim 4 wherein said metallic carrier beads comprise steel.

Claim 7

A process for coating electrostatographic carrier particles in accordance with claim 1 wherein said carrier particles are ferrite carrier beads having an average diameter of less than about 100 microns.

Claim 8

A process for coating electrostatographic carrier particles in accordance with claim 1 wherein said pyrolysis is conducted at temperatures of between about 680*C and 780*C.

Claim 9

A process for coating electrostatograPhic carrier particles having an average diameter of between about 1 micron and about 1, 000 microns with a homopolymer of p-xylylene comprising the steps of: a. heating unsubstituted, cyclic di-p-xylylene in a vacuum of between about 0.0001 and 10.0 millimeters of mercury to a temperature of between about 100*C and 240*C thereby forming vaporous cyclic di-p-xylylene dimer; b. pyrolyzing said vaporous dimer to form vaporous p-xylylene diradicals; c. agitating a bed of said carrier particles within a high frequency vibrating chamber; and d. contacting said vaporous p-xylylene diradicals with said agitated bed of carrier particles at a temperature above about 30*C by drawing said vacuum through said agitated bed of carrier particles thereby forcing said vaporous diradicals to travel a circuitous path directly through said agitated bed of carrier particles whereby sufficient contact is effected between said carrier particles and said vaporous diradicals to allow polymerization of said diradicals on said carrier particles at temperatures above the ceiling condensation temperature of said vaporous p-xylylene diradicals.

Claim 10

A process for coating electrostatograPhic carrier particles having an average diameter of between about 1 micron and about 1, 000 microns with a homopolymer of p-xylylene comprising the steps of: a. heating unsubstituted, cyclic di-p-xylylene in a vacuum of between about 0.0001 and 10.0 millimeters of mercury to a temperature of between about 100*C and 240*C thereby forming vaporous cyclic di-p-xylylene dimer; b. pyrolyzing said vaporous dimer to form vaporous p-xylylene diradicals; c. agitating a bed of said carrier particles within a high frequency vibrating chamber; and d. contacting said vaporous p-xylylene diradicals with said agitated bed of carrier particles at a temperature above about 30*C by drawing said vacuum through said agitated bed of carrier particles thereby forcing said vaporous diradicals to travel a circuitous path directly through said agitated bed of carrier particles whereby sufficient contact is effected between said carrier particles and said vaporous diradicals to allow polymerization of said diradicals on said carrier particles at temperatures above the ceiling condensation temperature of said vaporous p-xylylene diradicals.

Claim 11

In a process for coating electrostatographic carrier particles having an average diameter of between about 1 micron and about 1,000 microns with a p-xylylene polymeric material comprising the steps of: a. subliming a cyclic di-p-xylylene dimer to form a dimer vapor, and b. pyrolyzing said dimer vapor in a vacuum of between about 0.0001 and 10.0 millimeters of mercury to form vaporous p-xylylene diradicals, the improvement comprising; c. agitating a bed of said carrier particles within a high frequency vibrating chamber, and d. contacting said vaporous p-xylylene diradicals with said agitated bed of carrier particles at a temperature above about 30*C by drawing said vacuum through said agitated bed of carrier particles thereby forcing said vaporous diradicals to travel a circuitous path directly through said agitated bed of carrier particles whereby sufficient contact is effected between said carrier particles and said vaporous diradicals to allow polymerization of said diradicals on said carrier particles at temperatures above the ceiling condensation temperature of said vaporous p-xylylene diradicals.

Claim 12

In a process for coating electrostatographic carrier particles having an average diameter of between about 1 micron and about 1,000 microns with a p-xylylene polymeric material comprising the steps of: a. subliming a cyclic di-p-xylylene dimer to form a dimer vapor, and b. pyrolyzing said dimer vapor in a vacuum of between about 0.0001 and 10.0 millimeters of mercury to form vaporous p-xylylene diradicals, the improvement comprising; c. agitating a bed of said carrier particles within a high frequency vibrating chamber, and d. contacting said vaporous p-xylylene diradicals with said agitated bed of carrier particles at a temperature above about 30*C by drawing said vacuum through said agitated bed of carrier particles thereby forcing said vaporous diradicals to travel a circuitous path directly through said agitated bed of carrier particles whereby sufficient contact is effected between said carrier particles and said vaporous diradicals to allow polymerization of said diradicals on said carrier particles at temperatures above the ceiling condensation temperature of said vaporous p-xylylene diradicals.