Composite dual layer HEPA filter
AssigneeLydall, Inc.
InventorsScott Keeler, William Cambo
Life of this patent
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Abstract
The invention provides a composite, dual layer filtration material (1) having a gradient structure, comprising a dust layer (2) of wet laid dust fibers (5), a HEPA layer (3) of wet laid HEPA fibers (6) laid on top of the dust layer (2), and a transition zone (4) between dust layer (2) and HEPA layer (3) of a mixture of wet laid dust fibers (5) and wet laid HEPA fibers (6), and wherein the transition zone (4) so bonds the dust layer (2) to the HEPA layer (3) such that the composite (1) may be pleated into a pleated HEPA filtration material (30) without substantial disruption of the bond between the two layers. A corresponding process is also provided.
Claims20
A composite dual layer HEPA filtration material (1) comprising:
- (A) a dust layer (2) of wet laid dust fibers (5);
- (B) a HEPA layer (3) of wet laid HEPA fibers (6);
- and
- (C) a transition zone (4) between the dust layer (2) and the HEPA layer (3) of a mixture of wet laid dust fibers (5) and wet laid HEPA fibers (6), and wherein the transition zone (4) so bonds the dust layer (2) to the HEPA layer (3) such that the composite may be pleated into a pleated HEPA filtration material (30) without substantial disruption of the bond between the two layers and the composite is in the form of a gradient structure.
A process for producing a composite dual layer HEPA filtration material (1), comprising
- (A) wet laying a web (20) of dust fibers (5) from a water suspension thereof onto a formaceous body (22);
- (B) partially dewatering the web (20) of dust fibers (5);
- (C) wet laying a web (24) of HEPA fibers (6) from a water suspension thereof onto the forming web (20) of dust fibers (5);
- (D) partially dewatering the web (24) of HEPA fibers (6) such that some of the HEPA fibers (6) penetrate into an upper surface (9) of the web (20) of dust fibers (5) so as to form a transition zone (4) of a mixture of dust fibers (5) and HEPA fibers (6) between the web (20) of dust fibers (5) and the web (24) of HEPA fibers (6),
- (E) dewatering the so wet laid webs into a mat (29) of fibers;
- and
- (F) drying the mat of fibers,
- and wherein the transition zone (4) so bonds the dust layer (2) to the HEPA layer (3) such that the composite may be pleated into a pleated HEPA filtration material (30) without substantial disruption of the bond between the two layers and the composite is in the form of a gradient structure.
Dependencies are inferred from the claim text.