Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-06-09
2001-05-22
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S365000, C428S399000, C428S421000, C428S357000
Reexamination Certificate
active
06235388
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a fibrous material of fluorine-containing resin, particularly polytetrafluoroethylene containing a photodegrading catalyst and a deodorizing antibacterial cloth produced by using the fibrous material.
BACKGROUND ART
A photodegrading catalyst is a substance which is activated by photo energy having a short wave length such as light, particularly ultraviolet ray to exhibit catalytical ability for degrading compounds. Examples of known photodegrading catalyst are anatase-type titanium dioxide (TiO
2
), zinc oxide (ZnO), tungsten trioxide (W
2
O
3
) and the like. It is known that those photodegrading catalysts degrade compounds emitting malodorous smell and have sterilizing ability, thus being used for deodorizing and for antibacterial purpose. In order for the photodegrading catalysts to exhibit their function effectively, it is necessary to contact the catalysts directly to harmful substances. However if materials carrying the photodegrading catalysts are organic substances, there is a case where the catalysts degrade the materials.
Since fluorine-containing resins represented by polytetrafluoroethylene (PTFE) are materials being free from such degradation, articles in the form of membrane such as sheet and film which comprise PTFE as a matrix resin and contain a photodegrading catalyst have been proposed (“Kogyo Zairyou”, July 1996 (Vol. 44, No. 8). However in those forms, a photodegrading catalyst contained in PTFE does not function effectively, and there is a certain limit in its application to interior goods such as curtains.
A main object of the present invention is to provide a fibrous material having excellent deodorizing antibacterial property, by combining a photodegrading catalyst having deodorizing antibacterial activity with a fluorine-containing resin to make a fibrous material, thus enabling the photodegrading catalyst to be exposed more on the surface of the fibrous material, and to provide a cloth produced by using the fibrous material.
DISCLOSURE OF THE INVENTION
Namely the present invention relates to a fibrous material comprising a fluorine-containing resin having a photodegrading catalyst.
A preferred photodegrading catalyst is an anatase-type titanium dioxide. It is preferable that the catalyst is contained in or adhered to the fibrous material in an amount of from 1 to 50% (% by weight, hereinafter the same). It is particularly preferable that the catalyst is contained therein. Adhering can be carried out by coating, impregnating or the like. There is a case where PTFE is preferably a semi-sintered one. PTFE may contain an adsorbent having deodorizing activity. The adsorbent may be contained in a coating of the fibrous material.
The fibrous material is preferably in the forms mentioned below.
(1) Monofilament
(2) Staple fiber
(3) Continuous yarn split to the net-like form
(4) Finished yarn produced by mix-spinning or mix-twisting at least one of other fibrous materials to above (1) to (3)
Among them, the monofilament and staple fiber may have branches.
The other fibrous material used for the finished yarn is preferably an activated carbon fiber, and may contain the adsorbent or may be coated with the adsorbent.
Also the present invention relates to the deodorizing antibacterial cloth made of the fibrous material.
The deodorizing antibacterial cloth may comprise a non-woven fabric, woven fabric or knitted fabric made by combining at least one of the other fibrous materials. At least one of the other fibrous material may be an activated carbon fiber or a material containing the activated carbon fiber, or may be a material containing the adsorbent or coated with the adsorbent.
Further the deodorizing antibacterial cloth may be combined with a base fabric such as a non-woven fabric, woven fabric or knitted fabric made of other fibrous material to give a composite cloth. In that case, the base fabric may contain an activated carbon fiber or may contain the adsorbent or be coated with the adsorbent.
BEST MODE FOR CARRYING OUT THE INVENTION
The fibrous material of the present invention basically comprises the fluorine-containing resin having the photodegrading catalyst. Examples of the fluorine-containing resin are PTFE, PFA, FEP, ETFE and the like. Among them, PTFE is preferred. The following explanation is made based on PTFE, but is also applicable to other fluorine-containing resins.
PTFE used in the present invention encompasses homopolymer of tetrafluoroethylene (TFE) and a copolymer of TFE and other comonomer of at most 0.2%. Non-restricted examples of the comonomer are, for instance, chlorotrifluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl ether) and the like. Polymerization may be carried out by either of emulsion polymerization and suspension polymerization.
Examples of the photodegrading catalyst are anatase-type titanium dioxide, zinc oxide, tungsten trioxide and the like. The catalyst is usually in the form of powder. Among the photodegrading catalysts, anatase-type titanium dioxide is particularly preferable from the points that various malodorous substances such as ammonia, acetaldehyde, acetic acid, trimethylamine, methylmercaptan, hydrogen sulfide, styrene, methyl sulfide, dimethyl disulfide, isovaleric acid and the like can be degraded and that the degrading effect is exhibited even by weak light (ultraviolet ray).
A content of the photodegrading catalyst is preferably not less than 5% by weight from the viewpoint of rapid exhibition of deodorizing antibacterial activity and not more than 50% by weight from the viewpoint of easy molding, particularly from 10 to 40% by weight.
In the present invention, the “fibrous material” is a concept encompassing the above-mentioned monofilament, staple fiber, split yarn, finished yarn and the like.
Examples of methods for producing those PTFE fibrous materials having the photodegrading catalyst are as follows.
(1) Production of monofilament
(A) Production by emulsion spinning method (cf. U.S. Pat. No. 2,772,444)
An aqueous dispersion of PTFE fine powder, photodegrading catalyst powder, surfactant and coagulant (usable coagulant coagulated under acidic condition, for example, sodium alginate) is extruded through fine nozzles in an acidic bath, and a coagulated extrudate in the form of fiber is dried, sintered and stretched to give a monofilament.
(B) Production by opening a film (cf. WO94/23098)
(a) Production of PTFE powder containing titanium dioxide
An aqueous dispersion of: PTFE prepared by emulsion polymerization and an aqueous dispersion of the photodegrading catalyst powder are mixed, followed by stirring or adding an agglomerating agent (adding dropwise hydrochloric acid, nitric acid or the like) and then sting to agglomerate primary particles of PTFE and at the same time to coagulate the photodegrading catalyst powder therewith, thus giving secondary particles (average particle size: 200 to 1000 &mgr;m) obtained by incorporating the photodegrading catalyst powder into the agglomerated primary particles of PTFE. Then the secondary particles are dried to remove water and give a powder (a-1).
Another method is a method (a-2) for uniformly mixing a PTFE molding powder prepared by suspension polymerization and a photodegrading catalyst powder.
In the methods (a) for producing PTFE powder containing the photodegrading catalyst, the method (a-1) is preferable. In the method (a-1) it is possible that a larger amount of photodegrading catalyst powder is introduced (for example, 10.1 to 40% by weight), and a uniform molded article can be produced from the obtained powder. Also when a fibrous material is produced finally, the photodegrading catalyst powder is uniformly dispersed therein and excellent photocatalytical activity can be obtained. According to that method, the photodegrading catalyst powder can be contained uniformly in a large amount (for example, more than 30%).
(b) Production of un-sintered film
An auxiliary solvent for extrusion molding (for example, Isopar M which is a petroleum solvent available from Exxon Chemical Co., Ltd.) is added
Asano Jun
Kusumi Toshio
Yamamoto Katsutoshi
Daikin Industries Ltd.
Edwards N.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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