Corrosion-resistant ply bond adhesives and products and processes incorporating such adhesives
Corrosion-resistant adhesive compositions are provided. The compositions are useful for bonding together plies in multi-ply cellulosic fibrous structures. Multi-ply cellulosic fibrous structures incorporating the adhesives, products produced from such structures, and methods of producing the structures are also disclosed. The adhesive compositions incorporate a polyvinyl alcohol polymer and a corrosion inhibitor. The adhesive compositions may be sprayed or coated onto the cellulosic structures to bond layers of the structure to each other. The corrosion-resistant adhesive compositions are useful for preventing corrosion in the various devices used for handling and application of the adhesives such as spray equipment and applicator rolls. The cellulosic fibrous structures may be used to produce a variety of products including paper towels, toilet tissue, facial tissue, napkins, and other absorbent materials.
1. An adhesive composition comprising an aqueous solution of (i) a polyvinyl alcohol polymer with a degree of polymerization of about 1,600 to about 2,600, a number average molecular weight of about 70,000 to about 116,000, and being about 95 mole % to about 99.9 mole % hydrolyzed;
(ii) a neutralized amine corrosion inhibitor present in an amount such that about 0.25 wt % to about 1 wt % of the solids content of the adhesive formulation is derived from the neutralized amine corrosion inhibitor;
(iii) about 0.2 wt % to about 1.7 wt % of fumaric acid; and
(iv) about 4.0 wt % to about 7.0 wt % boric acid, based on the total weight of the polyvinyl alcohol polymer.
2. The adhesive composition of claim 1 wherein the polyvinyl alcohol polymer is selected from the group consisting of a homopolymer, a copolymer incorporating at least one comonomer selected from ethylene, methyl acrylate, a carboxylic acid, an alkyl acid vinyl ester, an acryl amide, and a vinyl amine.
3. The adhesive composition of claim 1 further comprising about 0.15 wt % to about 0.5 wt % of a defoamer.
4. The adhesive composition of claim 1 having a pH of about 5.4.
5. The adhesive composition of claim 1 , wherein the viscosity of the adhesive composition is about 70 cps to about 100 cps at 4% solids measured at 20° C.