Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Patent
1998-09-11
2000-08-22
Nutter, Nathan M.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
42840222, 264 41, 264 43, 264 433, 264 47, B01J 1302, C09D 523, H01F 144
Patent
active
061069469
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to microcapsules enclosing a therein a magnetic fluid, which are useful for imparting sound-absorbing and insulating ability to building materials, etc., and to a process for producing the same.
BACKGROUND ART
Materials hitherto sued for imparting sound-absorbing and insulating ability to building materials, etc. include sound absorbing materials such as porous materials, plate-shaped materials, perforated plates, slits, resonators, and sound insulating materials such as single materials, for example, a PC plate, plate glass, lead sheet, sintered metal sheet, light-weight concrete or gypsum board, and hollow double structure materials or laminated panel structure materials comprising the above-mentioned materials.
However, in the case of a thin plate-shaped metal, a number of steps are required before it can be used as the final product: that is, after having been made into the form of a thin plate, it must be processed to a predetermined size and shape, sometimes be processed three-dimensionally, and further, be subject to assembling and fitting. In the case of a porous material or a foamed plastic, since they have predominantly continuous holes, they are poor in resistance to local load, have a rough surface, and tend to adsorb water and dust; further, their sound absorption property is low in the low- and medium-pitched sound ranges. The processability of sound insulation sheets comprising a synthetic resin, such as vinyl chloride resin, and metallic fillers or iron oxide particles incorporated thereinto, is poor, and more over, they are brittle.
For the purpose of sound-proofing in the low- and medium-pitched sound ranges, for example, JP-A-5-279569 discloses a sound-proofing panel comprising a sandwich type panel with sand particles filled into the internal space of the panel. However, the panel has problems in that (i) it is difficult to fill sand particles into the internal space of the panel closely and without leaving clearance, and (ii) since sand is weighty, it is difficult to obtain light-weight panels. JP-A-5-279569 discloses a vibration-proofing material comprising a silicone gel having a specific pressure transfer characteristic and hollow microspheres made of an inorganic material, such as aluminosilicate, incorporate thereinto, JP-A-4-145174 discloses a vinyl chloride resin plastisol composition incorporated with hollow fillers, and JP-A-7-145331 discloses a water base coating material for vehicle constituent members comprising a water base coating composition and an organic hollow filler expandable upon heating or a specific amount of a foaming agent incorporated into the composition. However, these disclosures all aim at vibration proofing and dampening in the range of 100 Hz or less and teach nothing of sound absorption and insulation property.
DISCLOSURES OF THE INVENTION
The present invention has been achieved to resolve the above-mentioned problems. Thus, the magnetic fluid-enclosing microcapsule of the present invention comprises a shell and a magnetic fluid enclosed therein, the magnetic fluid being a dispersion of magnetic substance fine particles having an average particle diameter of 5-200 nm in a hydrophobic organic solvent and the shell being made of a thermoplastic resin. The heat-expandable microcapsule of the present invention comprises (i) a shell and (ii) a magnetic fluid and a hydrophobic liquid foaming agent both enclosed therein, the magnetic fluid being a dispersion of magnetic substance fine particles having an average particle diameter of 5-200 nm in a hydrophobic organic solvent and the shell being made of a thermoplastic resin. Further, the hollow microcapsule of the present invention comprises (i) a shell and (ii) a magnetic fluid and a vacant cell both included therein, the magnetic fluid being a dispersion of magnetic substance fine particles having an average particle diameter of 5-200 nm in a hydrophobic organic solvent and the shell being made of a thermoplastic resin. In particular, a hollow microcapsule
REFERENCES:
patent: 5521253 (1996-05-01), Lee et al.
patent: 5593680 (1997-01-01), Bara et al.
Nishizaki Akihiko
Shibamoto Toshihiko
Tanaka Koji
Matsumoto Yushi-Seiyaku Co. Ltd.
Nitto Boseki Co., Ltd
Nutter Nathan M.
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