Polyester film base having uniform high optical density

Claim 2

AN OPACIFIER FOR A POLYESTER COMPRISING A FLUID DISPERSION CONSISTING ESSENTIALLY OF FROM ABOUT 15 TO 20 PARTS OF CARBON BLACK HAVING AN ULTIMATE PARTICLE SIZE OF FROM ABOUT 5 TO ABOUT 1,000 MILLIMICRONS, FROM ABOUT 4 TO 5 PARTS OF POLYVINYLPYRROLIDONE, SAID POLYVINYLPYRROLIDONE HAVING A MOLECULAR WEIGHT IN THE RANGE FROM ABOUT 1,000 TO 100,000 AND FROM ABOUT 64 TO 80 PARTS OF GLYCOL, SAID GLYCOL BEING CHEMICALLY COMPATIBLE WITH SAID POLYVINYLPYRROLIDONE, ALL PARTS BEING BY WEIGHT.

Claim 3

The opacifier according to claim 1 wherein the glycol is ethylene glycol.

Claim 4

A process for preparing a fluid dispersion of carbon black particles in a liquid comprising milling together in a high shear mill until homogeneous from about 15 to 20 parts of carbon black particles having an ultimate particle size within the range of from about 5 to about 1,000 millimicrons, from about 4 to 5 parts of polyvinylpyrrolidone, said polyvinylpyrrolidone having a molecular weight in the range of from about 1,000 to 100,000, and from about 76 to 80 parts of glycol, said glycol being chemically compatible with said polyvinylpyrrolidone, all parts being by weight, diluting the dispersion with sufficient glycol to facilitate centrifugation of the dispersion, and passing the diluted dispersion through a centrifuge to remove oversize particles of carbon black.

Claim 5

A process for preparing a fluid dispersion of carbon black particles in a liquid comprising milling together in a high shear mill until homogeneous from about 15 to 20 parts of carbon black particles having an ultimate particle size within the range of from about 5 to about 1,000 millimicrons, from about 4 to 5 parts of polyvinylpyrrolidone, said polyvinylpyrrolidone having a molecular weight in the range of from about 1,000 to 100,000, and from about 76 to 80 parts of glycol, said glycol being chemically compatible with said polyvinylpyrrolidone, all parts being by weight, diluting the dispersion with sufficient glycol to facilitate centrifugation of the dispersion, and passing the diluted dispersion through a centrifuge to remove oversize particles of carbon black.

Claim 6

The process according to claim 3 wherein the glycol is ethylene glycol.

Claim 7

IN A PROCESS FOR PREPARING AN OPAQUE FORM OF POLYESTER, THE STEPS OF SAID PROCESS COMPRISING (1) INCORPORATING AN OPACIFYING AMOUNT OF CARBON PARTICLES INTO POLYESTER FORMING REACTANTS COMPRISING GLYCOL, DIALKYL TEREPHTHALATE AND CATALYSTS TO FORM A MIXTURE FOR FORMING A POLYESTER MONOMER BY AN ESTER EXCHANGE REACTION, (2) CHANGING SAID MIXTURE TO AN ESTER EXCHANGE REACTOR AND HEATING AND REACTING SAID MIXTURE TO FROM SAID MONOMER, (3) CONDENSING SAID MONOMER AND POLYMERIZING THE CONDENSED PRODUCT TO AN OPAQUE FLORM OF POLYESTER, THE IMPROVEMENT WHICH COMPRISES INCORPORATING SAID CARBON BLACK PARTICLES INTO SAID MIXTURE IN THE FORM OF A FLUID DISPERSION FREE OF OVERSIZED CARBON PARTICLES AND CONSISTING ESSENTIALLY OF A HOMOGENEOUS MIXTURE OF AN OPACIFYING AMOUNT OF CARBON BLACK PARTICLES, GLYCOL, AND CARBON BLACK DISPERSING AMOUNT OF POLYVINYLPYRROLIDONE, SAID CARBON PARTICLES HAVING AN ULTIMATE PARTICLE SIZE OF FROM ABOUT 5 TO 1,000 MILLIMICRONS, SAID DIALKYL TEREPHTHALATE BEING CHEMICALLY COMPATIBLE WITH SAID POLYVINYLPYRROLIDONE, AND SAID POLYVINYLOYRROLIDONE HAVING A MOLECULAR WEIGHT IN THE RANGE OF FROM ABOUT 1,000 TO ABOUT 100,000 AND BEING PRESENT IN THE DISPERSION IN THE RATIO OF AT LEAST ONE PART BY WEIGHT OF POLYVINYLPYRROLIDONE PER ABOUT 6 PARTS BY WEIGHT OF CARBON BLACK.

Claim 8

IN A PROCESS FOR PREPARING AN OPAQUE FORM OF POLYESTER, THE STEPS OF SAID PROCESS COMPRISING (1) INCORPORATING AN OPACIFYING AMOUNT OF CARBON PARTICLES INTO POLYESTER FORMING REACTANTS COMPRISING GLYCOL, DIALKYL TEREPHTHALATE AND CATALYSTS TO FORM A MIXTURE FOR FORMING A POLYESTER MONOMER BY AN ESTER EXCHANGE REACTION, (2) CHANGING SAID MIXTURE TO AN ESTER EXCHANGE REACTOR AND HEATING AND REACTING SAID MIXTURE TO FROM SAID MONOMER, (3) CONDENSING SAID MONOMER AND POLYMERIZING THE CONDENSED PRODUCT TO AN OPAQUE FLORM OF POLYESTER, THE IMPROVEMENT WHICH COMPRISES INCORPORATING SAID CARBON BLACK PARTICLES INTO SAID MIXTURE IN THE FORM OF A FLUID DISPERSION FREE OF OVERSIZED CARBON PARTICLES AND CONSISTING ESSENTIALLY OF A HOMOGENEOUS MIXTURE OF AN OPACIFYING AMOUNT OF CARBON BLACK PARTICLES, GLYCOL, AND CARBON BLACK DISPERSING AMOUNT OF POLYVINYLPYRROLIDONE, SAID CARBON PARTICLES HAVING AN ULTIMATE PARTICLE SIZE OF FROM ABOUT 5 TO 1,000 MILLIMICRONS, SAID DIALKYL TEREPHTHALATE BEING CHEMICALLY COMPATIBLE WITH SAID POLYVINYLPYRROLIDONE, AND SAID POLYVINYLOYRROLIDONE HAVING A MOLECULAR WEIGHT IN THE RANGE OF FROM ABOUT 1,000 TO ABOUT 100,000 AND BEING PRESENT IN THE DISPERSION IN THE RATIO OF AT LEAST ONE PART BY WEIGHT OF POLYVINYLPYRROLIDONE PER ABOUT 6 PARTS BY WEIGHT OF CARBON BLACK.

Claim 9

The process according to claim 5 wherein said fluid dispersion comprises by weight from about 15 to 20 parts of carbon black and from about 4 to 5 parts of polyvinylpyrrolidone.

Claim 10

The process of claim 6 wherein the dispersion comprises from about 76 to about 80 parts of glycol.

Claim 11

The process according to claim 5 wherein the glycol is ethylene glycol.

Claim 12

The process according to claim 5 wherein the dialkyl terephthalate is dimethyl terephthalate.

Claim 13

The process of claim 9 wherein the glycol is ethylene glycol.