Method of improving paper machine forming wire, felt and woven dryer belt performance by the application of peroxide containing solutions

Abstract

Embodiments are directed to methods for inhibiting contaminants formation during papermaking operation. The method includes preparing an aqueous solution having a pH greater than 7.0 and comprising peroxide; and applying the aqueous solution onto or within one or more of forming wires, press felts and woven through air drying (TAD) belts prior to contacting and transporting a wet paper web to inhibit the formation of wet paper web contaminants onto the surfaces of or within the forming wires, press felts and woven TAD belts.

Claims

1. A method for inhibiting contaminants formation during papermaking operation, the method comprising: preparing an aqueous solution having a pH greater than 7.0 and comprising peroxide; and applying the aqueous solution onto or within one or more of forming wires, press felts and woven through air drying (TAD) belts prior to contacting and transporting a wet paper web to inhibit the formation of wet paper web contaminants onto the surfaces of or within the forming wires, press felts and woven TAD belts, wherein the wet paper web contaminants comprise hydrogels having one or more of wet strength resins, dry strength resins, starch, starch derivatives, polyaminoamido epichlorohydrin adducts and reaction products, glyoxylated polyacrylamides and cationic papermaking polymers.

2. The method of claim 1 wherein the aqueous solution comprises peroxide, wet strength additive, and base.

3. The method of claim 2 wherein the base comprises at least one alkali metal hydroxide.

4. The method of claim 1 wherein the peroxide is hydrogen peroxide.

5. The method of claim 4 wherein the aqueous solution comprises the hydrogen peroxide in an amount from about 1% to about 15% by weight.

6. The method of claim 1 wherein the pH of the aqueous solution ranges from about 7.1 to about 13.5.

7. The method of claim 1 wherein the aqueous solution further comprises adjuvants selected from surfactants, peroxide stabilizers, peroxide activators, acids, or combinations thereof.

8. The method of claim 7 wherein the surfactant is selected from a group consisting of nonionic surfactants, anionic surfactants, cationic surfactants and zwitterionic surfactants.

9. The method of claim 1 wherein the aqueous solution comprises one or more solvents selected from the group consisting of glycol ether solvents, paraffinic solvents, naphthenic solvents, terpene solvents, alkyl alcohols, and aryl alcohols.

10. The method of claim 9 wherein the aqueous solution comprises solvent in an amount from about 6% to about 18% by weight.

11. The method of claim 1 wherein the aqueous solution is applied to the press felts at a temperature from about 5 C. to about 350 C.

12. The method of claim 1 wherein the aqueous solution has a dynamic surface tension of about 25 to about 40 dynes/cm.

13. The method of claim 1 wherein the aqueous solution is applied in an amount of about 100 ppm to about 50,000 ppm.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1A is a photographic depiction of a dried wet strength sample according to one or more embodiments of the present disclosure.

(2) FIG. 1B is a photographic depiction of a comparative dried wet strength sample.

(3) FIG. 1C is a photographic depiction of a comparative dried wet strength sample.

(4) FIG. 2 shows the IR spectra of dried wet strength samples according to one or more embodiments of the present disclosure.

(5) FIG. 3A is a photographic depiction of aqueous solution samples whether untreated or treated with bleach or peroxide according to one or more embodiments of the present disclosure.

(6) FIG. 3B is a photographic depiction of the sample of FIG. 3A inverted.

DETAILED DESCRIPTION

(7) Reference will now be made in detail to various embodiments of a method of treating papermaking forming wires, press felts and woven through air drying (TAD) belts that result in the prevention of the formation of hydrogels in these forming wires, press felts and woven TAD belts. These same methods of treating papermaking forming wires, press felts and woven TAD belts may be used to remove hydrogels from the same. The method includes the application of a peroxide containing solution either alone or in combination with an adjuvant to the papermaking forming wires, press felts and woven TAD belts. Embodiments of the methods can remove and/or prevent the formation of hydrogels in these felts. Thus, the methods may greatly improve the utility of press felts and other papermaking felts by preventing or eliminating detrimental deposition and deposits of hydrogels on or in the papermaking equipment.

(8) In various embodiments, a method of treating papermaking forming wires, press felts and woven TAD belts to inhibit contaminant formation includes applying a peroxide containing aqueous solution with or without an adjuvant to the papermaking forming wires, press felts and woven TAD belts. The application of the peroxide containing aqueous solution with or without an adjuvant improves the drainage of the papermaking forming wires, press felts and woven TAD belts by inhibiting the formation of contaminants thereon. Contaminants on forming wires, press felts and woven TAD belts impede drainage as the pores and avenues for drainage are blocked. In certain embodiments, the peroxide containing aqueous solution with or without adjuvants are applied as a single aqueous solution to the papermaking forming wires, press felts and woven TAD belts. In further embodiments, multiple aqueous solutions are applied to the papermaking forming wires, press felts and woven TAD belts.

(9) The term papermaking felts as used herein with reference to various embodiments is intended to include, but not necessarily be limited to, papermaking felts such as press felts, forming wires, through-air-drying (TAD) woven belts, and woven dryer belts. In some embodiments, the papermaking felts comprise forming wires, press felts, TAD woven belts and woven dryer belts. TAD woven belts are defined as papermaking felts specifically used in the Through Air Drying process for making paper.

(10) As stated above, embodiments of the present disclosure are directed to methods for inhibiting contaminants formation onto or within press felts during papermaking operation comprises preparing an aqueous solution having a pH greater than 7.0 and comprising peroxide; and then applying the aqueous solution onto or within the press felts prior to the papermaking operation to inhibit the formation of the wet paper web contaminants onto the surfaces of or within the press felts. Specifically, the peroxide may prevent the contaminants from gelling, crosslinking, or from adhering to other materials onto the surfaces of or within the press felts.

(11) In some embodiments, the contaminants in the papermaking felts include hydrogels as previously described. In some embodiments, the papermaking felts are contaminated with hydrogels in an amount from about 0.1 to about 100% by weight, including any value or ranges there between, as determined gravimetrically. The calculation for the wet soils is as follows: wet soils=wet weight of all papermaking contaminants/(dry weight of all papermaking contaminants+papermaking felt). A test piece of saturated press felt undergoes physical separation techniques to isolate the soils from the felt itself. These soils, when they are still wet, are weighed, dried and reweighed. For example, a wet press felt may contain 6.024 g wet soils separated from the felt. These soils then dry to a moisture free weight of 0.295 g. The separated felt is also completely dried and weighed, for example, to 9.92 g. In the example, then, the wet soils is calculated as: wet soils=6.024 g/(9.92 g+0.295 g)=0.590 or 59.0%. As described previously, wet soils include: hydrosols, hydrogels, and various combinations thereof. Hydrogels include, but are not limited to: wet and dry strength resins and Yankee dryer cylinder adhesives, including but not limited to polyamideamine-epichlorohydrin (PAE or PAEE) and glyoxalated polyacrylamide; natural and modified starches; alkylketene dimer; alkyl succinic anhydride and rosin-based sizing; carboxyl methylcellulose; guar gum; and retention aids, including but not limited to polyamines and polydadmacs. These polymers are variously described in literature known to those skilled in the papermaking industry. In addition, hydrogels will have a wet/dry ratio as calculated by (wet/dry ratio=% wet soils/% dry soils. In the example above, the % wet soils was already calculated as 59.0%. The dry soils is calculated similarly except using the weight of the dry soils instead of wet soils. In the example above: dry soils=0.295 g dry solids/9.92 g press felt=2.97%. The wet/dry ratio, then, would calculate as: wet/dry ratio=59.0%/2.97%=19.9. In one or more embodiments, the wet/dry ration may range from 8 to 100. In further embodiments, the wet/dry ration may range from 15-50.

(12) To inhibit these hydrogels, the peroxide containing aqueous solutions are applied to the press felts. As used herein, peroxide may encompass various compositions such as hydrogen peroxide, peracetic acid, sodium or potassium percarbonate. Various amounts are considered suitable for the hydrogen peroxide. For example, the aqueous solutions may include 1 to 35% by weight hydrogen peroxide, or from 1 to 15% by weight hydrogen peroxide.

(13) In various embodiments, the aqueous solution may comprise peroxide alone or in combination with other adjuvants or additives, for example, wet strength additives, and base. In further optional embodiments, the peroxide adjuvants may comprise one or more surfactants, peroxide stabilizers, peroxide activators, acids, or combinations thereof.

(14) Various alkaline compositions are contemplated for the base. For example, the base may comprise at least one alkali metal hydroxide. In one or more embodiments, the alkali metal hydroxide may include sodium hydroxide, potassium hydroxide, or combinations thereof. In one or more embodiments, the aqueous solution may comprise from 0 wt % to 25 wt % base or from 0.5 wt % to 5 wt % base. In addition to these bases, other activators are contemplated for activating the peroxide. These may include tetraacetylethylenediamine (TAED), iron chloride, iron sulfate (either ferric or ferrous) or other activators known to those skilled in the art.

(15) In some embodiments, the aqueous solution that is applied to the papermaking felt may further comprise a surfactant. The surfactant may be selected from nonionic surfactants, anionic surfactants, cationic surfactants and zwitterionic surfactants. In some embodiments, the surfactant may comprise dodecylbenzene sulfonate, sodium-1-octane sulfonate, sodium caprylyl sulfonate, alcohol ethoxylates, and combinations thereof. In various embodiments, the surfactant is present in the aqueous solution in an amount from about 1% to about 50% by weight based on the solids, or from about 1% to about 20% by weight based on the solids, or from about 6% to about 18% by weight based on the solids.

(16) The aqueous solution may further comprise an organic or inorganic stabilizer. These may include but are not limited to 1-hydroxyethane 1,1-diphosphonic acid (HEDP), diethylenetriaminepenta(methylenephosphonate) (DTMPA), amino tris(methylene phosphonic acid (ATMP), sodium acid polyphosphate, and various sodium, potassium, calcium and magnesium salts thereof. The aqueous solution may comprise 1 to 30% by wt. stabilizer.

(17) Optionally, other solvents, besides water, may be added to the aqueous solution. The aqueous solution may include one or more solvents selected from the group consisting of glycol ether solvents, paraffinic solvents, naphthenic solvents, terpene solvents, alkyl alcohols, and aryl alcohols. In one embodiment, the aqueous solution may comprise solvent in an amount from about 6% to about 18% by weight.

(18) In some embodiments, the aqueous solution comprises 10-10,000 ppm peroxide, 1-1000 ppm stabilizer and 10-5000 ppm surfactants. In some embodiments, the aqueous solution may be derived from solutions described in U.S. Pat. No. 7,101,832, which is incorporated by reference herein in its entirety.

(19) Various processing parameters are considered suitable for applying the aqueous solution onto the press felts prior to contacting and transporting a wet paper web comprising wet strength resins during the papermaking operation. For example, the aqueous solution may be applied at a pH from about 7.1 to 13.5, or about 7.1 to 9.5. In other embodiments, the single aqueous solution has a dynamic surface tension of about 25 to about 40. In some embodiments, the aqueous solution is applied to the papermaking felts at a temperature from about 5 C. to about 90 C. In various embodiments, the aqueous solution is applied to the papermaking felts at a temperature from about 350 C. to about 60 C. In some embodiments, the aqueous solution is applied to the papermaking felts at a dosage of about 100 ppm to about 50,000 ppm while a papermaking machine is operating. In some embodiments, the single aqueous solution is applied to the papermaking felts at a dosage of about 0.1% to about 100% while a papermaking machine is not operating.

(20) In various embodiments, the aqueous solution is applied to the papermaking felts through high pressure needle showers, fan showers, flooded nip showers, manual foaming equipment, or manual spraying equipment. In more particular embodiments, the aqueous solution can be applied through such means to the papermaking either continuously or intermittently.

(21) The improved drainage of the to the papermaking forming wires, press felts and woven TAD belts afforded from the inhibition and/or elimination of wet paper web contaminants on the to the papermaking forming wires, press felts and woven TAD belts allows the papermaking machines to run at relatively higher speeds. Specifically, the improved drainage necessitates less time for the dewatering of the wet web allowing the papermaking machines to run at an increased speed.

(22) Embodiments of the present disclosure also reduce or eliminate the need to shut down a papermaking machine in order to wash the papermaking felts. The aqueous solution may be applied during papermaking operations in contrast to previous methods of hydrogel elimination which necessitated stopping production to clean the papermaking machines. Specifically, the aqueous solution may be applied in a continuous or intermittent fashion prior to contacting and transferring a wet paper web to the press felts. Additionally, the application of the aqueous solution acting to inhibit contaminant formation during papermaking operation eliminates or reduces the need to remove already deposited contamination by preventing the initial contamination.

(23) Embodiments of the present disclosure also allow papermakers to modify the papermaking process by changing type, dosage or feedpoint, of a process chemical that tends to form troublesome hydrogels. Specifically, the dosage or formulation of the aqueous solution applied to the papermaking forming wires, press felts and woven TAD belts may be adjusted based on the specific papermaking chemicals utilized in a production run. Production of paper types or styles which generate increased formation of troublesome hydrogels may include an aqueous solution formulation target to the specific process chemicals utilized and/or the amount of aqueous solution applied to the papermaking forming wires, press felts and woven TAD belts may be increased. Further, the point of application of the aqueous solution to the papermaking forming wires, press felts and woven TAD belts may be adjusted to ensure retention of the aqueous solution immediately prior to contacting the wet paper web to the papermaking forming wires, press felts and woven TAD belts

(24) In order that various embodiments may be more readily understood, reference is made to the following examples, which are intended to illustrate various embodiments, but not limit scope thereof.

EXAMPLES

Example 1Visual Inspection

(25) Three solutions were prepared as shown in Table 1 to compare the contaminant formation inhibition of the method of the present disclosure to no treatment and treatment with sodium hypochlorite.

(26) TABLE-US-00001 TABLE 1 Comparative Comparative Sample 3 Sample 2 (Sodium Sample 1 (Untreated) Hypochlorite) Tap water (grams) 11.45 12.65 12.65 H.sub.2O.sub.2 (32%) (grams) 1.4 0 0 NaClO.sub.2 (12.5%) (grams) 0 0 1.4 Kymene 821 (grams) 6 6 6 NaOH 1N (grams) 1.15 1.35 1.0 pH 8.1 8.1 8.0

(27) The solutions described in Table 1 were prepared in the order listed in Table 1. Sequential preparation was necessary so that the inhibition chemistry was present in solution before the wet strength resin (Kymene 821) had a chance to begin to cross link. Kymene 821 is a wet strength resin based on polyaminopolyamide-epichlorohydrin (PAE) chemistry commonly used in the papermaking industry. At the completion of the sample preparations, each sample solution was dried in a 230 F. (110 C.) environment overnight to render all samples completely moisture-free. Referring to the photographs of FIGS. 1A, 1B, and 1C, the tested samples dried with distinct visual appearances. With reference to FIG. 1B, the Comparative Sample 2 (untreated solution) dried into a transparent, straw-colored brittle film. With reference to FIGS. 1A and 1C, the treated solutions, Sample 1 and Comparative Sample 3 respectively however, dried darker and opaque. Comparative Sample 3 (sodium hypochlorite solution) as illustrated in FIG. 1C maintained a film-like characteristic. In contrast, Sample 1 (hydrogen peroxide solution) as illustrated in FIG. 1A dried to a more marbled, amorphous mass.

Example 2IR Inspection

(28) Next, the dried samples were analyzed using IR spectroscopy with particular attention to the tertiary amine (1260 cm.sup.1) peak, which when heated would naturally cross link. Thus, this IR inhibition test measures the degree to which the functionality of wet strength resin to cross link and form hydrogels is inhibited.

(29) The resulting spectra are depicted in FIG. 2. The spectra have similar, but not identical, peaks and peak intensities. The differences and distinctions in the peaks and peak intensities provide guidance as to the cross linking behavior of the tertiary amines and the formation of hydrogels.

(30) The results of the IR spectroscopy were quantified using the ratio of the tertiary amine peak to a reference amide peak. The tertiary amine peak is a reactive peak for cross linkage. When that peak is present in the dried solution, it is evidence that the (WSR) has crosslinked. However, the hydrogen peroxide pretreatment chemistry of Sample 1 was found to break down the tertiary amine, such that minimal to no cross linking occurred. The absorbance measurements of the tertiary amine peaks (1260 cm.sup.1) were recorded, as were the absorbance measurements of a general amide peak (1635 cm.sup.1). This amide peak was consistent for each the three tested solutions, and thus provides a consistent reference across tests as a reference peak. The ratio of the tertiary amine peak absorbance to the reference peak absorbance was calculated to yield a relative tertiary amine peak for all solutions. Referring to Table 2 presented below, the larger the ratio, the larger the tertiary amine content relative to the reference peak, and thus the more cross linked the polymer. As is evident in Table 2, the sodium hypochlorite ratio (0.6299) of Comparative Example 3 is more similar to the untreated ratio (0.6975) of Comparative Example 2 than that of the peroxide treated ratio (0.4519) of Example 1. Thus, the peroxide solution is significantly better at reducing the cross linking ability of the wet strength resin (Kymene 821) compared to the hypochlorite. Based on these results it may be determined that Sample 1 does not have significant cross linking of the wet strength resin representing wet paper web contaminants. Conversely, it may be determined that Comparative Example 2 and Comparative Example 3 demonstrate significant cross linking of the wet strength resin.

(31) TABLE-US-00002 TABLE 2 Peak at 1260 Peak (tertiary at 1635 Ratio - Sample amine) (amide) Tertiary:Amide Conclusion Sample 1 0.0691 0.1529 0.4519 Not Cross (Peroxide) Linked Comparative 0.0987 0.1415 0.6975 Cross Sample 2 Linked (untreated) Comparative 0.0902 0.1432 0.6299 Cross Sample 3 Linked (sodium hypochlorite)

Example 3Viscosity Visual Inspection

(32) Further test samples were prepare to correspond to Sample 1, Comparative Example 2, and Comparative Example 3. Specifically, Sample 2 was prepared with H.sub.2O.sub.2 as was Sample 1, Comparative Example 4 was prepared without a treatment agent as was Comparative Example 2, and Comparative Example 5 was prepare with NaClO as was Comparative Example 3.

(33) Sample 2, Comparative Example 4, and Comparative Example 5 were prepared by combining ingredients in the order listed in Table 3. The formulations were prepared by adding 1.6 ml of NaOH (50%) to 80 grams (g) of Kymene 821 using an automatic pipette and then 5 g of the selected treatment agent was added to the solution of NaOH and Kymene 821. For Sample 2, the treatment agent was H.sub.2O.sub.2. For Comparative Sample 4, no treatment agent was added. For Comparative Sample 5, the treatment agent was NaClO. Each solution was shaken by hand between each ingredient addition to ensure complete mixing. After initial formulation of each solution the pH was measured. If the pH was not 112% the formulation was adjusted accordingly to move it into the desired range. As such, additional NaOH was added to Sample 2 and Comparative Sample 5 to achieve a pH of 11.09 in accordance with Table 3. Each prepared solution was placed into a 4 oz. glass jar and capped. The glass jars were placed in a 120 F. (48.9 C.) oven overnight and then removed and allowed to cool to room temperature. The viscosity of each solution was measured using a Brookfield viscometer (spindle 2/30 rpm) if not already in a gel form.

(34) TABLE-US-00003 TABLE 3 vis- Test Treatment Actives cosity Samples Formulation Agent (%) pH (cPs) Sample 2 80 g Kymene 821 + H.sub.2O 1.6 11.09 25 Comparative 1.6 mL of NaOH untreated 0 11.01 gel Sample 4 (50%) + 5 g Comparative Treatment Agent NaClO 0.625 (as 11.09 gel Sample 5 Cl.sub.2)

(35) Before viscosity measurement multiple photos were taken of each of the jars holding Sample 2, Comparative Sample 4, and Comparative Sample 5. Referring to FIGS. 3A and 3B, which include upright and inverted photos respectively of each solution, the viscosity control yielded by the hydrogen peroxide in Sample 2 is demonstrated. In the inverted photo of FIG. 3B, the untreated and NaClO treated PAE gels of Comparative Sample 4 and Comparative Sample 5 respectively are so thick that they cling to the bottle. That is the gelled solution may be visualized as remaining in place in the jar and not reacting to the force of gravity in a downward direction. In contrast, the peroxide treated PAE of Sample 2 remains in liquid form that easily flows when the bottle is inverted.

(36) It should now be understood that the various aspects of the method for inhibiting contaminants formation during papermaking operation are described and such aspects may be utilized in conjunction with various other aspects.

(37) In a first aspect, the disclosure provides method for inhibiting contaminants formation during papermaking operation. The method comprises preparing an aqueous solution having a pH greater than 7.0 and comprising peroxide; and applying the aqueous solution onto or within one or more of forming wires, press felts and woven through air drying (TAD) belts prior to contacting and transporting a wet paper web to inhibit the formation of wet paper web contaminants onto the surfaces of or within the forming wires, press felts and woven TAD belts.

(38) In a second aspect, the disclosure provides the method of the first aspect, in which the wet paper web contaminants comprise hydrogels having one or more of wet strength resins, dry strength resins, starch, starch derivatives, polyaminoamido epichlorohydrin adducts and reaction products, glyoxylated polyacrylamides and cationic papermaking polymers.

(39) In a third aspect, the disclosure provides the method of the first or second aspects, in which the aqueous solution comprises peroxide, wet strength additive, and base.

(40) In a fourth aspect, the disclosure provides the method of the third aspect, in which the base comprises at least one alkali metal hydroxide.

(41) In a fifth aspect, the disclosure provides the method of any of the first through fourth aspects, in which the peroxide is hydrogen peroxide.

(42) In a sixth aspect, the disclosure provides the method of the fifth aspect, in which the aqueous solution comprises the hydrogen peroxide in an amount from about 1% to about 15% by weight.

(43) In a seventh aspect, the disclosure provides the method of any of the first through sixth aspects, in which the pH of the aqueous solution ranges from about 7.1 to about 13.5.

(44) In an eighth aspect, the disclosure provides the method of any of the first through seventh aspects, in which the aqueous solution further comprises adjuvants selected from surfactants, peroxide stabilizers, peroxide activators, acids, or combinations thereof.

(45) In a ninth aspect, the disclosure provides the method the eighth aspect, in which the surfactant is selected from a group consisting of nonionic surfactants, anionic surfactants, cationic surfactants and zwitterionic surfactants.

(46) In a tenth aspect, the disclosure provides the method of any of the first through ninth aspects, in which the aqueous solution comprises one or more solvents selected from the group consisting of glycol ether solvents, paraffinic solvents, naphthenic solvents, terpene solvents, alkyl alcohols, and aryl alcohols.

(47) In an eleventh aspect, the disclosure provides the method of the tenth, in which the aqueous solution comprises solvent in an amount from about 6% to about 18% by weight.

(48) In a twelfth aspect, the disclosure provides the method of any of the first through third aspects, in which the aqueous solution is applied to the press felts at a temperature from about 5 C. to about 350 C.

(49) In a thirteenth aspect, the disclosure provides the method of any of the first through twelfth aspects, in which the aqueous solution has a dynamic surface tension of about 25 to about 40 dynes/cm.

(50) In a fourteenth aspect, the disclosure provides the method of any of the first through thirteenth aspects, in which the aqueous solution is applied in an amount of about 100 ppm to about 50,000 ppm.

(51) Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modifications and variations come within the scope of the appended claims and their equivalents.

(52) Unless otherwise indicated, the disclosure of any ranges in the specification and claims are to be understood as including the ranges itself and also anything subsumed therein, as well as endpoints.