Independent spacers and methods
Methods of making membrane elements for fluid or gas filtration, comprising applying feed or reject spacers, or intermediate spacers, or fold line protection strips, or end support strips directly to a membrane sheet, or to a substrate material which are subsequently applied to a membrane sheet, which thereby avoids contamination from directly printed adhesives, inks, or polymers, or damage from heat or radiation damage to the membrane sheet during direct application of spacers or patterns to the surface of the membrane sheet, thereby avoiding utilization of conventional feed spacer mesh materials. Membrane sheets and spiral wound filtration elements having spacers applied to defined regions of the sheet, in some embodiments having spacers mounted on substrates with different material properties, e.g., stiffness, than the underlying membrane.
1. A method of producing a membrane element for fluid processing, comprising:
(a) forming a spacer sheet comprising a first substrate sheet with a plurality of spacing features disposed thereon;
(b) adhering the spacer sheet to a membrane sheet, wherein the spacer sheet is adhered to the membrane sheet such that the spacing features are adhered to the membrane sheet; and
(c) separating the first substrate sheet from the spacing features after the spacing features are adhered to the membrane sheet, leaving the spacing features and not the first substrate sheet adhered to membrane sheet.
2. The method of claim 1 , further comprising spiral winding the membrane element to form a spiral wound element.
3. The method of claim 1 , further comprising placing the membrane element in a plate- and frame type membrane system.
4. A method of producing a membrane element for fluid processing, comprising:
(a) forming a spacer sheet comprising a first substrate sheet with a plurality of spacing features disposed thereon by:
(a1) joining a second substrate sheet to a first feature sheet at first surfaces thereof;
(a2) cutting pattern portions into the first feature sheet from a second surface of the first feature sheet, where the second surface is opposite the first surface, where the cutting does not completely penetrate the first feature sheet;
(a3) joining the first substrate sheet to the first feature sheet such that a first surface of the first substrate sheet is adjacent the second surface of the first feature sheet;
(a4) separating the first substrate sheet and the cut pattern portions of the first feature sheet from the second substrate sheet, such that the cut pattern portions of the first feature sheet and the first substrate form the spacer sheet; and
(b) adhering the spacer sheet to a membrane sheet.
5. The method claim 4 , wherein the spacing features are shaped such that they have features on one or more ends that facilitate removal of unwanted interstitial material.
6. The method claim 4 , wherein the spacing features are shaped having a portion that is a substantially straight line segment at an angle more than zero degrees and less than 90 degrees to an edge of the first substrate sheet.
7. The method of claim 4 , further comprising spiral winding the membrane element to form a spiral wound element.
8. The method of claim 4 , further comprising placing the membrane element in a plate- and frame type membrane system.
9. A method of producing a membrane element for fluid processing, comprising:
(a) forming a spacer sheet comprising a first substrate sheet with a plurality of spacing features disposed thereon by depositing spacing features directly on and bonded to a surface of a second substrate sheet; adhering the first substrate sheet to the spacing features with a bond strength greater than that of the spacing features to the second substrate sheet; and then separating the second substrate sheet from the spacing features.
10. The method of claim 9 , further comprising spiral winding the membrane element to form a spiral wound element.
11. The method of claim 9 , further comprising placing the membrane element in a plate- and frame type membrane system.