MX2007007619A - Corrosion-resistant ply bond adhesives and products and processes incorporating such adhesives - Google Patents

Abstract

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.

Description

UNION ADHESIVES BETWEEN CORROSION RESISTANT LAYERS AND PRODUCTS AND PROCEDURES THAT INCORPORATE SUCH ADHESIVES BACKGROUND OF THE INVENTION Fibrous network cellulosic structures are used in a variety of common products for the consumer. For example, fibrous cellulosic structures are used as paper towels, toilet paper, facial towels, handkerchiefs and the like, are commonly known as nonwovens. The high demand for these varied paper products has created a demand for improved versions of the products and methods for their manufacture. Although single layer structures are used, multi-layer cellulosic fibrous structures are well known for use in the production of consumer products. Said products are cellulosic fibrous structures that have more than one layer laid one on top of the other. These layers or plies usually come together to avoid delamination, to maintain structural integrity when the multi-layer non-woven end product is in use. The joining of individual cellulosic fibrous webs into multiple layer structures is often achieved by etching the structures in a conversion equipment without applying an adhesive. In a typical etching process, two or more layers are fed through a nozzle formed between parallel etching rollers, axially juxtaposed. The engraving handles on these rollers force each layer into engagement and in contact relation with the opposite layer. The compressed regions of the layers have the benefits of producing an aesthetically pleasing pattern as well as providing means for joining and maintaining the layers in face-to-face contact. It is often difficult to achieve control of the junction of the layer or network. Inadequate, excessive or inconsistent bonding of the layers can clog the complex, the high-speed machinery; It can generate high wear, or cause reduction in production speed and poor quality. The strength of the bond with the engraving (without adhesive) can vary depending, among other things, on the water content or the dryness of the fibrous networks, and the humidity of the ambient air. Although the engraving bond can sometimes be improved by increasing the pressure on the engraving rollers, said pressure can wear out more quickly the engraving rolls, particularly the female roll, which is usually the softest roll that is made with a mixed material on which prints the pattern with the opposite male roll of engraved metal. In addition, the days and loads on both engraving rollers can also wear them out prematurely if they are subjected to increased pressure for a long time.

In a different procedure, fibrous layers can be joined using a chemical adhesive instead of etching. For example, the patent of E.U.A. 5,466,318 discloses a method for laminating networks using a water-based adhesive. Bonding with adhesive is sometimes used to avoid problems related to etching, but adhesives also cause problems, such as "deep bonding" or "blocking", where adjacent laminates join together and prevent unrolling the rolled product from its roller.- The lack of uniformity in the joint also causes problems, such as wrinkling of the fabric, and poor printing. The patents of E.U.A. 6,602,577, 6,635,134, and 6,649,025 describe multilayer paper structures in which an adhesive composition is used to bond the layers together. A variety of adhesive compositions are disclosed, including adhesives based on polyvinyl alcohol. The patent of E.U.A. No. 3,135,648 discloses that polyvinyl alcohol adhesives with high wet tack can be prepared by adding a water soluble boron compound to the copolymer and adding an acid at a low pH.

BRIEF DESCRIPTION OF THE INVENTION This description relates to corrosion resistant adhesive compositions which are suitable for use in bonding layers in multi-layer cellulose fibrous structures. This disclosure also relates to multilayer cellulosic fibrous structures that incorporate adhesives described herein, to products produced with such structures, and to methods for producing the structures. The adhesive compositions incorporate a polyvinyl alcohol polymer as well as at least one corrosion inhibitor. The corrosion inhibitor can be selected from neutralized amine compounds; aqueous mixtures of polyoxylates; a mixture of at least one mercaptan and an amine compound; sodium benzoate; a combination of sulfurous acid, a dipotassium salt, and diethylaminoethanol; or mixtures thereof. Adhesive compositions are aqueous solutions incorporating dissolved solids, which include from about 89% by weight to about 95% by weight of a polyvinyl alcohol polymer and from about 0.25% by weight to about 1.0% by weight of the corrosion inhibitor. The polyvinyl alcohol polymer can be a homopolymer or a copolymer incorporating at least one comonomer such as ethylene, methyl acrylate, a vinylamine, a carboxylic acid, vinyl esters of branched alkyl acid, such as vinyl esters of alpha-branched carboxylic acids having 5 and 9 to 11 carbon atoms, which they are available with Resolution Performance Products under the designations VeoVa®, vinyl amines, other comonomers. In one embodiment, the polyvinyl alcohol polymers useful in accordance with the compositions, products and methods described herein, have a degree of polymerization of from about 300 to about 4,000, a number average molecular weight of from about 13,300 to about 400,000. , and hydrolyzed in an amount of about 88 mol% to about 99.9 mol%. In another embodiment formulations produced with polyvinyl alcohol polymers having a number average molecular weight of about 124,000 to about 186,000 provide good adhesive performance, without migration of the adhesive in the sheet layers in a variety of solid concentrations including four parts. solid. The formulations also do not exhibit corrosive activity. Adhesive compositions can be borated to provide a suitable consistency for the application of the adhesive in a variety of processes and equipment, and to improve wet adhesion. The adhesive compositions can be sprayed or coated onto cellulosic structures to bond the layers of the structure together. Corrosion inhibitors that incorporate a neutralized amine; aqueous mixtures of polyoxylates; mixtures of at least one mercaptan and at least one amine compound, sodium benzoate, a combination of sulfurous acid, a dipotassium salt, diethylaminoethanol; or mixtures thereof, turn out to be special and surprisingly compatible with the adhesive compositions described herein. In one embodiment, sodium benzoate is selected as the corrosion inhibitor. The corrosion-resistant adhesive compositions are useful for preventing corrosion in various devices that are used to handle and for the application of adhesives, such as spray equipment and applicator rolls. Cellulosic fibrous structures can be used in a variety of products including paper towels, toilet paper, facial towels, handkerchiefs, and other absorbent products.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of the application of the adhesive formulations described herein.

DETAILED DESCRIPTION OF THE INVENTION A variety of consumer products are commonly produced from structures that incorporate multiple layers of cellulosic fibrous networks, such as thin paper webs. These products include paper towels, toilet paper, facial towels, handkerchiefs, and other absorbent materials, such as materials for the absorption of body fluids. This Description refers to corrosion resistant adhesives for joining together multiple cellulosic fibrous networks. United networks are useful for the production of a variety of products for the consumer, including those mentioned above. The adhesives described herein are characterized by their ease of application, for their usefulness as laminate binders and for their inhibition of corrosion for process equipment. This disclosure also relates to multi-layer structures that incorporate the adhesive described herein, to products produced from said structures, and to methods for producing the structures. The adhesives described herein can be applied to all types of cellulosic fibrous webs, and to products such as paper towels, toilet paper, face towels, handkerchiefs, and the like. However, adhesives were found to be particularly useful in the production of multi-layer paper towel products. The adhesives described herein incorporate a polyvinyl alcohol polymer as well as at least one corrosion inhibitor. Adhesive compositions are aqueous solutions that incorporate dissolved solids of about 89% by weight to about 95% by weight of the polyvinyl alcohol polymer, and from about 0.25% by weight to about 1.0% by weight of the corrosion inhibitor. The polyvinyl alcohol polymer can be a homopolymer or a copolymer that incorporates at least one comonomer such as ethylene, methyl acrylate, a carboxylic acid, a branched alkyl vinyl ester, such as vinyl esters of alpha-branched carboxylic acids having 5 and 9 to 11 carbon atoms which are available with Resolition Performance Products under the designations VeoVa® a archilamide, and other comonomers. It should be understood that the term "copolymer" as used herein is a polymer that incorporates at least two monomer units and therefore includes terpolymers and the like. In one embodiment, the polyvinyl alcohol polymers described herein have a degree of polymerization of about 300 to about 4000, number average molecular weights of about 13,300 to about 400,000, and are from about 885 molar to about 99.9 mole% hydrolysates . In another embodiment, the polyvinyl alcohol homopolymer polymers described herein have a degree of polymerization of from about 1600 to about 2600, number average molecular weights of from about 70,000 to about 116,000, and are from about 95 mole% to about 99.9. % molar hydrolysates. Exemplary polyvinyl alcohol polymers which are useful for inclusion in the adhesives described herein, are available from Celanese Chemicals under the designations SM 73, MH82, and SH95EXP. These polyvinyl alcohol polymers have PVOH grades of stickiness. The SM73 has a viscosity of 1200 to 1600 cps @ 10% solid and 20 ° C and a pH of 4.0; MH82 has a viscosity of 4200 to 5900 cps @ 10% solids and 20 ° C, and a pH of 4.4 to 4.9; and the SH95EXP has a viscosity of 65 to 105 cps @ 4.0% solids and 20 ° C and a pH of 4 to 5.5. The polyvinyl alcohol polymers useful for inclusion in the adhesives described herein may be pierced by reaction with a boron compound. Exemplary suitable boron compounds are boric acid, methyl borate, boron trifluoride, boric anhydride, pyroborates, peroxoborates and boranes. In one embodiment the boron compound is sodium tetraborate decahydrate (borax). The boron compound can be added to the polyvinyl alcohol coating formulation or can be applied as a coating of aqueous solution to the already formed polyvinyl alcohol. The boiling of polyvinyl alcohol is useful for controlling the viscosity of the polyvinyl alcohol adhesive composition. This regulation of viscosity is provided by the formulation of a complex between boric ion and hydroxyl products in the polyvinyl alcohol polymer. Even a pH of more than 8 exists the borate ion and is available to interlock and cause gelation of the adhesive composition. Even lower pH, the borate is bound by hydrogen and is not available for interlacing, in this way the gelation caused by borate is reversible. Due to the boiling of the polyvinyl alcohol, a gelled adhesive composition can be produced which can be easily applied in and / or adhere to the cellulosic network. Boration is also useful for providing highly tacky adhesives as described in the U.S. 3,135,648. In one embodiment, the boric acid can be used as a boring agent and the boric acid can be incorporated into the adhesive formulation at a concentration of about 3.0 wt% to about 15 wt%, based on the total weight of the alcohol polymer poly. In another embodiment, the boric acid may be incorporated into the adhesive formulations at a concentration of about 4.0 wt% to about 10.0 wt% based on the total weight of the polyvinyl alcohol polymer. In another embodiment, boric acid can be incorporated into the adhesive formulations at a concentration of about 4.0% to about 7.0% by weight based on the total weight of the polyvinyl alcohol polymer. In one embodiment, the corrosion inhibitor can be a neutralized amine compound. The neutralized amines useful in the adhesive formulations described herein are a variety of commercially available neutralized amine formulations. Exemplary neutralized amines which are useful for inclusion in the adhesive formulations are available from JACAM Chemicals, LLC in Sterling, Kansas under the designations WCI1 56N, WCI 100, WCI 155, and WCI 1157.

In a second embodiment, the corrosion inhibitor can be an aqueous mixture of polyoxylates. Aqueous polyoxylate blends that are useful in the adhesive formulations described herein are a variety of commercially available aqueous polyoxolate formulations. A suitable aqueous mixture of polyoxylates is commercially available with Nalco under the designation Nalco ACT 52211. In another embodiment, the corrosion inhibitor can be a mixture of at least one mercaptan and at least one amine compound. An exemplary corrosion inhibitor of this type is commercially available from Henkel under the designation Rodino 2002. In another embodiment, the corrosion inhibitor may be sodium benzoate. An exemplary corrosion inhibitor of this type is commercially available from Velsicol Chemical Corporation under the designation Provenis SG. In another embodiment, the corrosion inhibitor may be a combination of sulfurous acid, a dipotassium salt, diethylaminoethanol. An exemplary corrosion inhibitor of this type is commercially available from GE Betz under the designation Optigard MCA 6254. In certain embodiments, the adhesive formulations may include a mixture of one or more of these corrosion inhibitors. In one embodiment, from about 89% by weight to about 95% by weight of the solids content of the adhesive formulation is derived from the polyvinyl alcohol polymer and from about .25% by weight to about 1.0% by weight of the solids content of the adhesive formulation is derived from the corrosion inhibitor. In another embodiment, from about 90% by weight to about 95% by weight of the solids content of the adhesive formulation is derived from the polyvinyl alcohol polymer and from about 0.3% by weight to about 0.6% by weight of the solids content it is derived from the corrosion inhibitor. In another embodiment, from about 93.0% by weight to about 94.5% by weight of the solids content of the adhesive formulation is derived from the polyvinyl alcohol polymer and about 0.4% by weight to about 0.55% by weight of the solids content. drift from the corrosion inhibitor. The corrosion inhibitors that are within these concentration scales can be selected from any of the corrosion inhibitors described above, or from mixtures of one or more of the identified corrosion inhibitors. In specific embodiments, from about 25% by weight to about 1.0% by weight of the solids content of the adhesive formulation is derived from a neutralized amine corrosion inhibitor. In one embodiment, the viscosity of the adhesive formulation incorporating borated polyvinyl alcohol polymers ranges from about 70 cps to about 100 cps at 4% solids measured at 20 ° C using a Brookfield LVD at 60 rpm (shank # 2).

The adhesive formulations described herein may also include a variety of other components. For example, in certain embodiments, the formulations may also incorporate from about 0.15% by weight to about 0.5% by weight of a defoamer, and from about 0.2% by weight to about 1.7% by weight of an organic acid to control the pH of the final adhesive formulation. Exemplary useful organic acids are fumaric acid, citric acid and mixtures thereof. In one embodiment, the adhesive formulations described herein dissolve in water to form an aqueous solution of the adhesive formulations. The components of the adhesive formulations described herein are solids at temperatures and at standard pressures. With respect to aqueous solutions, the amount of solids dissolved therein can be described as the percentage of solids of the weight of the entire adhesive solution. In one embodiment, the aqueous adhesive formulations described herein have a solids content ranging from about 2.0 wt% to about 8.0 wt%. In a second embodiment, the solids content of the aqueous adhesive formulations ranges from about 2.5% by weight to about 5.0% by weight. In a third embodiment, the solids content is from about 3.0 wt% to about 4.5 wt%.

Unexpectedly it has been determined that adhesive formulations incorporating polyvinyl alcohol polymers that fall within the parameters delineated herein, exhibit superior performance characteristics, as compared to polyvinyl alcohol polymers that are outside the parameters described above. For example, polyvinyl alcohol polymers having lower hydrolysis levels are unsuitable for the uses described herein. It has been determined that adhesive formulations incorporating polyvinyl alcohol polymers with hydrolysis levels of 87% to 97% do not exhibit sufficient water resistance, which results in inadequate moisture resistance in toilet paper applications. of multiple layers. For example, in the test of a formulation incorporating an 88% hydrolyzed polyvinyl alcohol polymer, it revealed zero wet tensile strength when used in multi-layer tissue applications, while a corresponding formulation of 99% hydrolyzed polyvinyl alcohol polymer exhibited a wet bond tensile strength of at least about 3.03 kg per 2.54 linear cm. The molecular weight of the polyvinyl alcohol polymers is also a factor in the performance of the adhesive formulations described herein. For example, at contents of the aqueous adhesive formulation, of 4% by weight, it has been determined that polyvinyl alcohol polymers having average wet molecular weights of less than 70,000 do not perform well. Adhesives incorporating said homopolymers tend to migrate through the cellulosic fiber substrate. The multilayer structures described herein are produced from at least two cellulosic fibrous networks. In theory, the number of networks is unlimited. However, in a first embodiment, the multiple layer structure incorporates two networks. In a second embodiment, the multilayer structure has three layers and in a third embodiment, the structure incorporates 4 networks. Adjacent networks of the structure adhere to each other by at least one adhesive formulation as described above. Adhesive formulations can be applied to a surface of each adjacent network, or the surface of one of the appropriate networks. For each interface between the bonded layers of the structure, the adhesives can be applied at a concentration of less than about 20.0 g / m2 in one embodiment. In another modality, the adhesives can be applied at a concentration of about 5.0 g / m2 to about 15.0 g / m3. In a third embodiment, the adhesives can be applied at a concentration of about 5.0 g / m2 to about 10.0 g / m2. A schematic representation of a two-layer structure according to this description is shown in Figure 1. A first network 1 having two surfaces 2 and 3 adheres to a second network 4 having two surfaces 5 and 6. A layer of at least one of the adhesive formulations described herein is arranged between the surfaces 2 and 5 of the first and second networks respectively. The adhesive can be applied to each surface 2 and to the surface 5, or it can be applied only on the surface 2 or the surface 5. It is generally less complicated and more economical to apply the adhesive to only one of the two adjacent surfaces. The adhesive formulation can be applied to one or more surfaces by any known means, such as the spray that is written in the U.S. patent. 6,635,134 or by applicator rolls as described in the US patent. 6,649,025. once the adhesive was applied, the first network 1 is joined to the second network 4 by any suitable means, such as press rolls that are described in the E: U.A patent. 6,649,025. When the networks are joined, a laminated structure is formed. After the application of the adhesive formulations, the formulations are dried by evaporation or by absorption of the water in the present, leaving the solid component of the formulations to adhere the laminate layers to one another. It has been found that the adhesive formulations described herein provide good bond strength between the layers of the laminated structures even at low rates of adhesive use. For example, adhesive formulations provide levels of adhesion between cellulosic fibrous networks comparable to traditional polyvinyl alcohol-based adhesives at usage ratios of 20% to 30% lower than conventional polyvinyl alcohol formulations, based on the total weight of the adhesive formulations used. As mentioned before, the inclusion of the neutralized amine as a corrosion inhibitor in the adhesive formulations described herein, eliminates or reduces corrosion of the metal parts in the various process equipment used to apply the adhesive formulations. to produce multiple layer structures.

Exemplary data Non-corrosive adhesive formulations incorporate corrosion inhibitors, as described herein, and the corrosivity of the adhesives was tested without the corrosion inhibitors. The corrosivity of various adhesive formulations in mild steel coupons was tested. The performance of the exemplary adhesive formulations described herein was tested against control adhesive formulations without corrosion inhibitors. Specifically, three control formulations without corrosion inhibitors were tested, one without a pacido, another with citric acid, and another with fumaric acid. The formulation without an acid (A1) contained 100% of a commercial PVOH polymer available with Celanese Chemicals under the designation Celvol 165. This polymer of HPV has a degree of hydrolysis% of more than 99.3, a viscosity @ 4% solids and ° C from 62 to 72 centipoises.

These formulations are identified in Table 1 as the A1-A3 formulations respectively. All the control formulations were aqueous solutions with 4% by weight solids. A first set of six adhesive formulations was tested, incorporating corrosion inhibitors, which are examples of formulations described herein. The first set of exemplary formulations incorporated citric acid or fumaric acid. Exemplary formulations incorporated one of three corrosion inhibitors, a neutralized amine (WCI 1 156 N), an aqueous mixture of polyoxyalkylates (Nalco ACT 5221 1) and a mixture of a mercaptan and an amine compound (Rodino 2002). Exemplary formulations are identified in Table 1 as B1-B6. All exemplary formulations of the first set were aqueous solutions with a solids content of 4% by weight.

TABLE I In the test, preforms or soft steel coupons measuring 7.62 cm by 1.27 were used, having a thickness of 0.1588 cm and weighing 10-1 1.5 grams that were placed in solutions of 200 grams of adhesives with a content of 4% solids. The solutions and coupons were used in a regulated oven at a constant temperature of 54.4 ° C. Adhesive solutions were evaluated after intervals of 24, 48, 72, 96, 120 or 168 hours for the color change. After 168 hours in the solutions, the metal coupons were removed, cleaned and dried, reweighed to determine the weight of the lost metal for each coupon. The PVOH control solution without an acid exhibited a clear color and 0% metal loss after 168 hours of exposure. Adhesive solutions incorporating an acid and in which no corrosion inhibitor is present, exhibited a dark brown color and from 0.74 wt.% To 0.75 wt.% Weight loss of the metal coupon after 168 hours. Weight loss was minimized in solutions containing acid and a corrosion inhibitor. The details of these results are presented in table 2.

TABLE II As can be seen in the information, the combination of neutralized amine corrosion inhibitor and fumaric acid showed unexpectedly superior results compared to the other corrosion inhibitor combinations. In particular, the reported results can be observed with respect to the "B6" formulation. A second set of five exemplary adhesive formulations was tested in accordance with the formulations described herein. All formulations incorporate an amine corrosion inhibitor neutralized and a defoamer. The defoamer used was an alkaline oxide copolymer. Said defoaming agent is commercially available with Harcos Chemicals under the designation HL-36. Exemplary formulations are depicted in Table 3 as formulations C1-C5. All formulations were prepared by dissolving them in water, with a solids content of 4.0% by weight, based on the total weight of the formulation.

TABLE III Exemplary formulations C1-C5 were also tested against preforms or soft steel coupons measuring 7.62 cm by 1.27 cm, having a thickness of 0.1588 cm and weighing 10-11.5 grams, were placed in solutions of 200 grams of adhesives with a content of solids of 4%. The solutions and coupons were placed in a regulated oven at a constant temperature of 54.4 ° C. The adhesive solutions were evaluated after intervals of 24, 48, 72, 96 and 144 hours for the color change. After 144 hours in the solutions, the metal coupons were removed, cleaned, dried and weighed again to Determine the weight of the metal loss of each coupon. All formulations exhibited a light color and minimal metal loss after 144 hours of exposure. The details of these results are expressed in table 4 TABLE IV As can be seen in table 4, formulations incorporating a neutralized amine corrosion inhibitor and a defoamer performed well, as evidenced by light colors and minimal weight loss. Other classes of corrosion inhibitors were evaluated in an additional test. In this test, corrosivity was evaluated in certain PVOH adhesive formulations incorporating sodium benzoate and a combination of sulphurous acid, a dipotassium salt, diethylaminoethanol as corrosion inhibitors. The corrosivity of these adhesive formulations was compared with adhesive formulations incorporating a neutralized amine corrosion inhibitor.

The corrosivity of different adhesive formulations tested in mild steel coupons was tested. Specifically, two formulations of neutralized amine at pH 4.2 and 5.2 were compared with formulations incorporating sodium benzoate and a combination of sulfurous acid, a dipotassium salt, and diethylaminoethanol corrosion inhibitors having pH of 4.2 and 5.2. All formulations incorporate the commercial PVOH polymer available with Celanese Chemicals under the designation C165 as described in more detail above. The sodium benzoate used was a commercial product available from Vesicol Chemical Corporation under the designation Probenz SG. The combination of sulfurous acid, dipotassium salt, and diethylaminoethanol that was used was a commercial product available with GE Betz under the designation Optiguard MCA624. The pHs of the solutions were controlled with the addition of fumaric acid as indicated. All formulations incorporated a defoamer, HL-36, as described above. These formulations are identified in Table 5 as the CA-C5 formulations (neutralized amine formulations corresponding to the C4 and C5 formulations described above), D1-D2 (sodium benzoate) and E1 -E2 (sulfurous acid combination, salt dipotassium, and diethylaminoethanol), respectively with the applicable pH indicated. All formulations were aqueous solutions with a solids content of 4.0% by weight, with the weight percentage of the solids athbuible to the individual components as indicated.

TABLE V For the test, preforms or soft steel coupons measuring 7.62 cm by 1.27 cm were used, having a thickness of 0.1588 cm and weighing 10-11.5 grams, which were placed in solutions of 200 grams of adhesives with a solids content of 4. %, or were suspended in a closed chamber containing a vapor of the solutions. The coupons were exposed to the solutions for 168 hours under controlled temperatures. The degree of corrosion was determined by the weight loss of the coupon during the exposure. The details of these results are presented in Tables VI-VIII.

TABLE VI TABLE VII TABLE VIII Tables VI to VIII report the results of the corrosion tests with the three different corrosion inhibitors, with the two different pH of the adhesive solution, two different temperatures for the steel coupons exposed to the solutions in the liquid and vapor phases . The results are extrapolated with the corrosion time of one year and are expressed in terms of micras for loss per year ("MPA"). Of course, with respect to the different scales that are pointed out in the present, any upper limit mentioned can be combined with any lower limit for the selected secondary scales.

All patents and publications to which reference is made herein are incorporated herein by reference in their entireties. Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of the invention which is defined by the following claims.

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. An adhesive composition comprising an aqueous solution of (i) a polyvinyl alcohol polymer with a degree of polymerization of from about 330 to about 4,000 and which is hydrolyzed from about 88 mol% to about 99.9 mol%; (ii) a corrosion inhibitor.

2. The adhesive composition according to claim 1, further characterized in that the polyvinyl alcohol and the corrosion inhibitor are dissolved in an aqueous solution with a solids content of about 2% by weight to about 8% by weight of solids. , based on the total weight of the aqueous solution.

3. The adhesive composition according to claim 2, further characterized in that from about 89% by weight to about 95% by weight of the solids content are derived from the polyvinyl alcohol polymer and from about 0.25% by weight to about 1.0%. by weight of the solids content is derived from the corrosion inhibitor.

4. The adhesive composition according to claim 3, further characterized in that the corrosion inhibiting compound is selected from the group consisting of neutralized amines; aqueous mixtures of polyoxylates; mixtures of at least one mercaptan and at least one amine compound; sodium benzoate; a combination of sulfurous acid, a dipotassium salt, diethylaminoethanol; and mixtures thereof.

5. The adhesive composition according to claim 3, further characterized in that the corrosion inhibiting compound is sodium benzoate.

6. - The adhesive composition according to claim 5, further characterized in that the polyvinyl alcohol polymer is bored.

7. - The adhesive composition according to claim 6, further characterized in that the polyvinyl alcohol and the corrosion inhibitor are dissolved in an aqueous solution with a solids content of about 3% by weight to about 5% by weight of solids , based on the total weight of the aqueous solution.

8. The adhesive composition according to claim 7, further characterized in that the polyvinyl alcohol polymer is borated with a boron compound selected from the group consisting of boric acid, methyl borate, boron trifluoride, boric anhydride, pyroborates, peroxoborates, and boranos.

9. The adhesive composition according to claim 8, further characterized in that the boron compound is acidic boric acid incorporated in from about 3% by weight to about 15% by weight of the total weight of the polyvinyl alcohol polymer.

10. The adhesive composition according to claim 9, further characterized in that 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 , a vinyl ester of alkyl acid, an achide amide, and a vinyl amine.

11. A multi-layer cellulosic fibrous laminate structure, comprising: (a) a first layer of a cellulosic fibrous material having first and second surfaces; (b) a second layer of a cellulosic fibrous material having first and second surfaces, wherein the first surface of the second layer adheres to the first surface of the first layer; (c) an adhesive composition comprising (i) a polyvinyl alcohol polymer with a degree of polymerization of from about 300 to about 4,000, and which is hydrolysed from about 88.0 mol% to about 99.9 mol%; and (ii) a corrosion inhibiting compound; and (d) wherein the adhesive composition is disposed between the first and second layers.

12. The multilayer cellulosic fibrous laminate structure according to claim 11, further characterized in that the cellulosic fibrous material comprises toilet paper.

13. - The multi-layer cellulose fibrous laminate structure according to claim 12, further characterized in that from about 89% by weight to about 95% by weight of the adhesive composition is derived from the polyvinyl alcohol polymer and from about 0.25% by weight to about 1% by weight of the adhesive composition is derived from the corrosion inhibitor.

14. - The multilayer cellulosic fibrous laminate structure according to claim 13, further characterized in that the structure is a paper towel, and wherein the corrosion inhibitor is selected from the group consisting of neutralized amines; aqueous mixtures of polyoxylates; mixtures of at least one mercaptan and at least one amine compound; sodium benzoate; a combination of sulfurous acid, a dipotassium salt, diethylaminoethanol; and mixtures thereof.

15. - The multi-layer structure according to claim 14, further characterized in that the corrosion inhibiting compound is sodium benzoate and wherein the polyvinyl alcohol polymer is borated.

16. - A method for producing a multilayer cellulosic fibrous laminate, comprising: (i) a polyvinyl alcohol polymer with a degree of polymerization of about 300 to about 4,000, and which is hydrolyzed at about 88.0 mol% to about 99.9 % molar; and (ii) a corrosion inhibiting compound to a first layer of a cellulosic fibrous material having a first and a second layer surfaces for forming a coating of the adhesive on the first surface of the first layer of the cellulosic fibrous material; and (b) contacting the first surface of the first layer of the cellulosic fibrous material with a second layer of a cellulosic fibrous material having a first surface and a second surface, to adhere the first surface of the first layer of the cellulosic fibrous material with the first surface of the second layer of the cellulose fibrous material.

17. - The method according to claim 16, further characterized in that the polyvinyl alcohol and the corrosion inhibitor of the adhesive composition are dissolved in an aqueous solution with a solids content of about 2% by weight to about 8% by weight. weight of solids, based on the total weight of the aqueous solution, and wherein the corrosion inhibitor is selected from the group consisting of neutralized amines; aqueous mixtures of polyoxylates; mixtures of at least one mercaptan and at least one amine compound; sodium benzoate; a combination of sulfurous acid, a dipotassium salt, diethylaminoethanol; and mixtures thereof.

18. - The method according to claim 17, further characterized in that from about 89% by weight to about 95% by weight of the solids content of the adhesive composition is derived from the polyvinyl alcohol polymer, and about 0.25% by weight to about 1% by weight of the solids content is derived from the corrosion inhibitor.

19. - The method according to claim 18, further characterized in that the corrosion inhibiting compound of the adhesive composition is sodium benzoate, and wherein the first layer of cellulosic fibrous material and the second layer of cellulosic fibrous material comprise toilet paper .

20. - The method according to claim 19, further characterized in that the adhesive composition is applied to the first surface of the first layer of the paper material of the bath at a concentration of about 5 g / m2 to about 15 g / m2 of the first surface of the first layer.