Process for enlarging the surface of particles

• US 6,076,277 A
• Filed: 03/16/1999
• Issued: 06/20/2000
• Est. Priority Date: 09/26/1996
• Status: Expired due to Fees

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Eyerer, Peter, Emmerich, Rudolf, Elsner, Peter
• Primary Examiner(s): Gravini, Steve
• Application Number:
  US09/254,673
• Time in Patent Office: 462 Days
• Field of Search: 34/245, 34/259, 34/263, 34/265, 34/279, 34/380, 34/381, 34/402, 219/687, 219/688, 219/689, 426/465, 426/289, 426/242, 426/640, 210/634, 210/137, 210/511
• US Class Current: 34/263
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: B01J 20/3441 Regeneration or reactivation by electric current, ultrasound or irradiation, e.g. electromagnetic radiation such as X-rays, UV, light, microwaves
• CPC Class Codes: B29B 13/065 of powder or pellets
• CPC Class Codes: B29B 13/08 by using wave energy or particle radiation
• CPC Class Codes: B29B 9/16 Auxiliary treatment of granules
• CPC Class Codes: B29C 2035/0855 using microwave
• CPC Class Codes: D06M 10/003 Treatment with radio-waves or microwaves
• CPC Class Codes: D06P 5/2083 heating with IR or microwaves
• CPC Class Codes: F26B 3/347 Electromagnetic heating, e.g. induction heating or heating using microwave energy

Abstract

In order to enlarge the surface of particles which absorb liquids at leasto a limited extent, the particles are exposed to a liquid or to a humid atmosphere containing this liquid at least until said liquid has penetrated into the area of the particles close to their surface, and the liquid-containing particles are then irradiated with micro-waves until the penetrated liquid evaporates. The surface of the particles is torn down to the depth of penetration of the liquid and thus enlarged, or the particles break up, creating small broken pieces with an irregular and enlarged surface.

Claims

1. A method for reducing the size of liquid absorbing polymer particles comprising the steps of:

a) subjecting the particles to one of a liquid and a moist atmosphere containing said liquid;

b) waiting a sufficient length of time such that said liquid penetrates into the polymer particles; and

c) irradiating the particles, following step b), with microwaves to suddenly evaporate said liquid, wherein an associated spontaneous pressure increase in molecular compound of the polymer particles explodes a structure of the polymer particles.

2. The method of claim 1, wherein step c) comprise exploding said structure of the polymer particles proximate surfaces of the polymer particles.

3. The method of claim 1, wherein step c) comprises completely exploding the polymer particles.

4. The method of claim 1, wherein steps a) and b) comprise subjecting the polymer particles to one of said liquid and a damp atmosphere containing said liquid for a sufficient amount of time that said liquid penetrates only into regions proximate surfaces of the polymer particles.

5. The method of claim 1, wherein steps a) and b) comprise subjecting the polymer particles to one of said liquid and a damp atmosphere containing said liquid for a sufficient length of time that said liquid penetrates into a core of the polymer particles.

6. The method of claim 4, wherein step c) comprises producing polymer particles with roughened surfaces.