Dry chemically bound nonwovens which are flushable and dispersible
This invention is directed to methods of incorporating a trigger such as boric acid, boric acid salts, sodium sulfate, or other salts, into a nonwoven web substrate for the preparation of dry nonwoven products which are redispersible when put in contact with large amounts of water or liquid. In one method, the trigger is in a dry powder form and is incorporated into the nonwoven fibers followed by treatment of the fibers with an aqueous redispersible binder, and binding and drying the web. Another method is to saturate a dry bonded nonwoven web with an aqueous solution of the trigger and then dry the saturated web. Yet another method is to apply an aqueous solution of the trigger to the web followed by applying a redispersible aqueous binder to the web and then heating and drying the web.
1. A method of making a dry bonded redispersible non-woven web comprising:
(a) applying dry particles selected from the group consisting of boric acid, an organic salt, and an inorganic salt, to a nonwoven web of fibers to form a nonwoven web of fibers containing the dry particles dispersed therein;
(b) applying an aqueous dispersion of a redispersible binder to the nonwoven web of fibers containing the dry particles dispersed therein to form a wet nonwoven web of fibers; and
(c) drying and binding the wet nonwoven web of fibers to form a fry redispersible nonwoven web.
2. The method of claim 1 wherein the organic salt or inorganic salt is an ammonium, an alkali metal or an alkaline earth metal salt of carbonic acid, citric acid, acetic acid, succinic acid, phosphoric acid, sulfuric acid or hydrochloric acid.
3. The method of claim 1 wherein the redispersible binder comprises a poly(vinyl alcohol) stabilized poly(vinyl acetate) polymer emulsion or a poly(vinyl alcohol) stabilized vinyl acetate-ethylene polymer emulsion formed by emulsion polymerization.
4. The method of claim 1 wherein the dry particles are applied to the web of nonwoven of fibers via superabsorbent particle dosing lines or are sprinkled onto the web through oscillating screens.
5. The method of claim 1 wherein the average diameter of the dry particles is about 50 to 2000 microns.
6. A method of making a dry bonded redispersible non-woven web comprising:
(a) applying an aqueous solution of an organic or inorganic salt selected from the group consisting of an ammonium, an alkali metal and an alkaline earth metal salt of carbonic acid, citric acid, acetic acid, succinic acid, phosphoric acid, sulfuric acid or hydrochloric acid, to a nonwoven web of fibers to form a wet nonwoven web of fibers;
(b) applying an aqueous dispersion of a redispersible binder to the wet nonwoven web of fibers to form a wet nonwoven web of fibers containing a redispersible binder; and
(c) drying and binding the wet nonwoven web of fibers containing a redispersible binder to form a dry bonded redispersible nonwoven web.
7. A method of making a dry bonded redispersible non-woven web comprising:
(a) applying an aqueous solution of an ammonium, an alkali metal or an alkaline earth metal salt of carbonic acid, citric acid, acetic acid, succinic acid, phosphoric acid, sulfuric acid or hydrochloric acid to a bonded nonwoven web of fibers to form a wet bonded nonwoven web of fibers;
(b) drying the wet bonded nonwoven web of fibers to form a dry bonded redispersible nonwoven web.
8. The method of claim 7 wherein the redispersible binder comprises a poly(vinyl alcohol) stabilized poly(vinyl acetate) polymer emulsion or a poly(vinyl alcohol) stabilized vinyl acetate-ethylene polymer emulsion formed by emulsion polymerization.