# US 4,391,927 A · Erasable inks containing thermoplastic block copolymers

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,391,927 A
- Document ID: US4391927A
- Status: Granted
- Kind: A
- Application number: 06/318,307
- Filed: 1981-11-05
- Granted: 1983-07-05
- Earliest claimed: 1981-11-05
- Assignees: The Gillette Company
- Inventors: Robert F. Farmer, III
- Web page: https://patentgrep.com/patent/US4391927A

## CPC

- C09D 153/02: Vinyl aromatic monomers and conjugated dienes
- C09D 11/18: specially adapted for ball-point writing instruments
- Y10S 525/901: Radial block
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

An erasable ink containing a thermoplastic block copolymer, pigment particles, and a solvent. In a preferred embodiment, an erasable ink requiring little or no pressurization is provided by employing a mixture of radial and linear block copolymers and a mixed solvent system falling within a specific range of solubility parameter. Polybutene and poly-alpha-methylstyrene are preferred additives to decrease smearing tendency.

## Claims

### Claim 1

An erasable ink for use in a ball-point writing instrument consisting essentially of a pigmented organic solvent solution containing a thermoplastic block copolymer having an arrangement of A (thermoplastic) and B (rubbery) blocks selected from the class consisting of ABA, (AB).sub.n X and (--AB)--.sub.n ; in which said thermoplastic blocks are selected from the class consisting of styrene, ester and urethane blocks; in which said rubbery blocks are selected from the class consisting of butadiene, isoprene and ethylene-butylene blocks; in which the ratio of said rubbery blocks to said thermoplastic blocks is from 60:40 to 90:10; in which the solubility parameter of said organic solvent is from about 7 to about 10.5; and containing an effective amount up to about 10% by weight of said solution of an additive to increase erasability selected from the class consisting of polybutenes and poly-alpha-methylstyrene.

### Claim 2 (depends on 1)

An erasable ink as described in claim 1 in which said block copolymer has butadiene or isoprene midblocks.

### Claim 3 (depends on 1)

An erasable ink as described in claim 1 in which said block copolymer has butadiene or isoprene midblocks and in which the solubility parameter of said organic solvent ranges from about 8.1 to about 8.7.

### Claim 4 (depends on 1)

An erasable ink as described in claim 1 in which said block copolymer has butadiene or isoprene midblocks and in which said organic solvent is a mixture of at least two organic solvents, at least one of which has a solubility parameter of about 7.2 to about 7.8, at least one other of which has a solubility parameter of about 8.7 to about 8.9 and in which said mixture has a solubility parameter of about 8.1 to about 8.7.

### Claim 5 (depends on 1)

An erasable ink as described in claim 1 in which said block copolymer has butadiene or isoprene midblocks, in which the solubility parameter of said organic solvent ranges from about 8.1 to about 8.7 and in which the concentration of pigment does not exceed about 10% by weight.