Magnetic deinking of waste papers
US5851349A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 3, 1997 |
| Grant date | Dec 22, 1998 |
| Priority date | — |
| Expiry date | Sep 3, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02W30/64
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
An improved process is disclosed for deinking waste paper which contains nonimpact printed papers printed with xerographic and laser inks by repulping the waste paper to form a slurry in the presence of an agglomeration agent and magnetite and subjecting the slurry to a magnetic field to remove the agglomerated ink particles, whereby the improvement comprises replacement of a portion of the agglomeration agent with a copolymer of styrene and acrylic monomers which copolymer is further characterized by having a Ring and Ball softening point of 70.degree.-105.degree. C. and an number average molecular weight of 2,000 to 10,000. The magnetic treatment preferably is conducted at ambient or greater temperature, at neutral to alkaline pH, and at a low pulp consistency. Also, the process may be employed as an additional step in a conventional process for removing inks from reprographic printed papers, such as ink removal by screening, flotation, centrifugal cleaning, washing, and sedimentation with or without decantation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.