RU2762277C2 - Composition, its application and method for removing and preventing contaminations of paper-making equipment with moisture-resistant resins - Google Patents

Abstract

FIELD: paper industry.

SUBSTANCE: invention relates to the use of a composition containing an aqueous solution of weak organic acid, a surfactant, a catalyst containing a divalent metal ion, and, optionally, a solvent containing glycol ester for the cleaning of paper-making equipment from contaminations with moisture-resistant resins, wherein these contaminations are formed, when using moisture-resistant resins in the paper making process, where moisture-resistant resin is polyamide-epichlorohydrin (PAE) resin, by a contact of paper-making equipment with the specified composition. The invention also relates to a method for preventing the contamination of paper-making equipment with moisture-resistant resins during the paper making process, where the method includes a stage of a contact of equipment with a composition containing an aqueous solution of weak organic acid, a surfactant, a catalyst containing a divalent metal ion, and, optionally, a solvent containing glycol ester, before, and/or during, and/or after the addition of moisture-resistant resin during the paper making process, where moisture-resistant resin is polyamide-epichlorohydrin (PAE) resin.

EFFECT: obtaining a composition for the cleaning of paper-making equipment.

13 cl, 1 dwg, 6 tbl, 2 ex

Description

FIELD OF TECHNOLOGY

The present invention relates to compositions and methods for cleaning papermaking equipment from wet resins contamination and / or for preventing wet resins from contaminating papermaking equipment.

LEVEL OF TECHNOLOGY

Wet resins are the main additives used in the papermaking process. The use of wet resins such as polyamide epichlorohydrin (PAE) will build up crosslinked chemicals and contaminate wet press felts, causing the felts to lose their permeability over time and reduce the rate of water absorption. Paper mills spend time and money cleaning up contaminated cloth, and even have to change cloth frequently.

Chemicals that are currently used to clean wet press felts or to remove contamination with wet-strength resin are either very corrosive or very acidic. These chemicals are corrosive, non-renewable or non-biodegradable and are not suitable for safe handling. In addition, these products not only remove moisture-resistant resin contamination, but can also damage the felt itself.

Thus, there is a need for products that are highly effective in cleaning papermaking equipment from wet resins contamination and / or prevent wet resins from contaminating papermaking equipment without significantly damaging the equipment. In addition, the products must be safe to handle and environmentally friendly, such as renewable and / or biodegradable.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to provide a solution or amelioration to the problems encountered in the prior art.

In particular, one of the objects of the present invention is to provide a substantially biodegradable, safe and effective composition for cleaning papermaking equipment from wet resins and / or preventing wet resins from contaminating papermaking equipment.

An exemplary composition according to the present invention for cleaning papermaking equipment from moisture resistant resins and / or preventing moisture resistant resins from contaminating papermaking equipment contains an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent metal ion , and, optionally, a solvent containing a simple glycol ether.

In accordance with the present invention, a typical method for cleaning papermaking equipment from wet-strength resin contamination includes the steps of contacting the equipment with a composition containing an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent metal ion, and optionally a solvent containing a simple glycol ether.

In accordance with the present invention, a typical method for preventing contamination of papermaking equipment with wet resins during papermaking includes the steps of contacting the equipment with a composition containing an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent metal ion, and optionally a glycol ether containing solvent before, and / or during and / or after the addition of the wet strength resin to the papermaking process.

According to the present invention, a typical use of a composition comprising an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent metal ion, and optionally a solvent containing a glycol ether, is to clean equipment by contacting the equipment with composition.

The compositions of the present invention have many advantages. The compositions are renewable, environmentally friendly and highly biodegradable. The cleaning compositions are FDA compliant and thus suitable for cleaning equipment used in the manufacture of paper, cardboard or similar materials used in contact with food. The compositions are stable and highly effective for cleaning papermaking equipment from moisture resistant resins and preventing moisture resistant resins from contaminating papermaking equipment without damaging the equipment. The components of the composition can also exhibit a synergistic effect, and the composition can have a higher purification efficiency or productivity than the individual components.

Other objects, features and advantages of the present invention will become apparent from the following detailed description. However, it should be understood that the detailed description and specific examples indicating specific embodiments of the invention are given by way of illustration only, as various changes and modifications in the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF DRAWINGS

The following schematic drawings are part of the present description and are included to further demonstrate some aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with a detailed description of the embodiments of the invention presented herein.

Figure 1. Process for cleaning the press felts as described in example 2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a stable, renewable, environmentally friendly, FDA compliant and safe to handle composition for cleaning papermaking equipment with wet resins and / or preventing wet resins from contaminating papermaking equipment.

Some embodiments of the present invention relate to compositions for cleaning papermaking equipment from wet resins and / or preventing wet resins from contaminating papermaking equipment containing an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent ion metal, and optionally a solvent containing a simple glycol ether. In some embodiments, the weak organic acid is selected from the group consisting of citric acid, adipic acid, glycolic acid, and combinations thereof, preferably citric acid. In some embodiments, the glycol ether solvent is selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and a combination thereof. In some embodiments, the surfactant is selected from the group consisting of isotridecyl alcohol ethoxylate, dodecanol ethoxylate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated, polyethylene glycol trimethylnonyl ether, polysorbates, surface active substances containing ethoxylated secondary alcohols, and combinations thereof. In some embodiments, the divalent metal ion is selected from the group consisting of Ca ⁺² , Mg ⁺² , Ba ⁺² , Fe ⁺² , Cu ⁺² , Ni ⁺² , Mn ^+2, and Co ⁺² , preferably Fe ⁺² , Ca ⁺² , Cu ⁺² or Ni ⁺² . In some embodiments, the implementation of the concentration of the weak organic acid is in the range of 15-45%, preferably 20-30%. In some embodiments, the concentration of the glycol ether solvent is in the range of 0-15%, preferably 3-8%. In some embodiments, the surfactant concentration is in the range of 2-25%, preferably 5-13%. In some embodiments, the concentration of the divalent metal ion containing catalyst is in the range of 0.01-5%, preferably 0.25-3%. In some embodiments, such cleaning compositions are further diluted with one or more diluents, the diluent / composition ratio (w / w) being in the range of 500: 1-0: 1, preferably 200: 1-9: 1.

Some embodiments of the invention relate to methods for cleaning papermaking equipment from moisture resistant resins, the method comprising the steps of contacting the equipment with a composition comprising an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent metal ion, and optionally a solvent containing a simple glycol ether. In some embodiments, the weak organic acid is selected from the group consisting of citric acid, adipic acid, glycolic acid, and combinations thereof, preferably citric acid. In some embodiments, the glycol ether solvent is selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and a combination thereof. In some embodiments, the surfactant is selected from the group consisting of isotridecyl alcohol ethoxylate, dodecanol ethoxylate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated, polyethylene glycol trimethylnonyl ether, polysorbates, surface active substances containing ethoxylated secondary alcohols, and combinations thereof. In some embodiments, the divalent metal ion is selected from the group consisting of Ca ⁺² , Mg ⁺² , Ba ⁺² , Fe ⁺² , Cu ⁺² , Ni ⁺² , Mn ^+2, and Co ⁺² , preferably Fe ⁺² , Ca ⁺² , Cu ⁺² or Ni ⁺² . In some embodiments, the implementation of the concentration of the weak organic acid is in the range of 15-45%, preferably 20-30%. In some embodiments, the concentration of the glycol ether solvent is in the range of 0-15%, preferably 3-8%. In some embodiments, the surfactant concentration is in the range of 2-25%, preferably 5-13%. In some embodiments, the concentration of the divalent metal ion containing catalyst is in the range of 0.01% -5%, preferably 0.25-3%. In some embodiments, such cleaning compositions are further diluted with one or more diluents, the diluent / composition ratio (w / w) being in the range of 500: 1-0: 1, preferably 200: 1-9: 1. In some embodiments, cleaning is carried out at elevated temperatures. In some other embodiments, the contact time is from 0.1 second to 5 hours, preferably from 30 seconds to 1 hour, more preferably from 1 minute to 30 minutes. In some other embodiments, the papermaking equipment is a wet press felts, a dryer sheet, papermaking equipment used in a papermaking process that uses wet resins, or another surface of a papermaking machine. In some embodiments, the wet strength resin is a polyamide epichlorohydrin (PAE) resin.

Some embodiments of the present invention relate to methods for preventing wet resins from contaminating papermaking equipment in the papermaking process, the method comprising the steps of contacting the papermaking equipment with a composition comprising an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst comprising a divalent metal ion, and optionally a solvent containing glycol ether, before, and / or during and / or after the addition of the wet strength resin to the papermaking process. In some embodiments, the weak organic acid is selected from the group consisting of citric acid, adipic acid, glycolic acid, and combinations thereof, preferably citric acid. In some embodiments, the glycol ether solvent is selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and a combination thereof. In some embodiments, the surfactant is selected from the group consisting of isotridecyl alcohol ethoxylate, dodecanol ethoxylate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated, polyethylene glycol trimethylnonyl ether, polysorbates, surface active substances containing ethoxylated secondary alcohols, and combinations thereof. In some embodiments, the divalent metal ion is selected from the group consisting of Ca ⁺² , Mg ⁺² , Ba ⁺² , Fe ⁺² , Cu ⁺² , Ni ⁺² , Mn ^+2, and Co ⁺² , preferably Fe ⁺² , Ca ⁺² , Cu ⁺² or Ni ⁺² . In some embodiments, the implementation of the concentration of the weak organic acid is in the range of 15-45%, preferably 20-30%. In some embodiments, the concentration of the glycol ether solvent is in the range of 0-15%, preferably 3-8%. In some embodiments, the surfactant concentration is in the range of 2-25%, preferably 5-13%. In some embodiments, the concentration of the divalent metal ion containing catalyst is in the range of 0.01-5%, preferably 0.25-3%. In some embodiments, such cleaning compositions are further diluted with one or more diluents, the diluent / composition ratio (w / w) being in the range of 500: 1-0: 1, preferably 200: 1-9: 1. In some other embodiments, the contact time is from 0.1 second to 5 hours, preferably from 30 seconds to 1 hour, more preferably from 1 minute to 30 minutes. In some other embodiments, the papermaking equipment is a wet press felts, a dryer sheet, papermaking equipment used in a papermaking process that uses wet resins, or another surface of a papermaking machine. In some embodiments, the wet strength resin is a polyamide epichlorohydrin (PAE) resin.

Some embodiments of the present invention relate to the use of a composition comprising an aqueous solution of a weak organic acid, a surfactant, preferably a nonionic surfactant, a catalyst containing a divalent metal ion, and optionally a solvent containing a glycol ether, to clean equipment by contact equipment with composition. In some embodiments, the weak organic acid is selected from the group consisting of citric acid, adipic acid, glycolic acid, and combinations thereof, preferably citric acid. In some embodiments, the glycol ether solvent is selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and a combination thereof. In some embodiments, the surfactant is selected from the group consisting of isotridecyl alcohol ethoxylate, dodecanol ethoxylate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated, polyethylene glycol trimethylnonyl ether, polysorbates, surface active substances containing ethoxylated secondary alcohols, and combinations thereof. In some embodiments, the divalent metal ion is selected from the group consisting of Ca ⁺² , Mg ⁺² , Ba ⁺² , Fe ⁺² , Cu ⁺² , Ni ⁺² , Mn ^+2, and Co ⁺² , preferably Fe ⁺² , Ca ⁺² , Cu ⁺² or Ni ⁺² . In some embodiments, the implementation of the concentration of the weak organic acid is in the range of 15-45%, preferably 20-30%. In some embodiments, the concentration of the glycol ether solvent is in the range of 0-15%, preferably 3-8%. In some embodiments, the surfactant concentration is in the range of 2-25%, preferably 5-13%. In some embodiments, the concentration of the divalent metal ion containing catalyst is in the range of 0.01% -5%, preferably 0.25-3%. In some embodiments, such cleaning compositions are further diluted with one or more diluents, the diluent / composition ratio (w / w) being in the range of 500: 1-0: 1, preferably 200: 1-9: 1. In some embodiments, cleaning is carried out at elevated temperatures. In some other embodiments, the contact time is from 0.1 second to 5 hours, preferably from 30 seconds to 1 hour, more preferably from 1 minute to 30 minutes. In some embodiments, the equipment is papermaking equipment. In some other embodiments, the papermaking equipment is a wet press felts, a dryer sheet, papermaking equipment used in a papermaking process that uses wet resins, or another surface of a papermaking machine. In some embodiments, the papermaking equipment contains contaminants resulting from the use of wet resins in the papermaking process. In some embodiments, the wet strength resin is a polyamide epichlorohydrin (PAE) resin.

Other embodiments of the present invention are discussed in this application. Any embodiment discussed in relation to one aspect of the invention is applicable to other aspects of the invention, and vice versa. Each embodiment described herein is understood to be embodiments of the present invention that are applicable to all aspects of the invention. It is contemplated that any embodiment discussed herein may be practiced with respect to any method or composition of the invention, and vice versa. In addition, the compositions and kits of the invention can be used to achieve the methods of the invention.

In some embodiments, the equipment is papermaking equipment. In some embodiments, the papermaking equipment contains contaminants resulting from the use of wet resins in the papermaking process.

The composition according to the invention contains an aqueous solution of a weak organic acid. The use of a weak organic acid makes the composition softer and safer, both for process operators and workers, and for the equipment to be cleaned. At the same time, however, it contributes to an unexpectedly sufficient cleansing effect that is achieved using the composition. According to one preferred embodiment, the concentration of the organic acid in the composition is in the range of 10-45%, preferably 20-30%.

The weak organic acid of the present invention may have a pK _a greater than 1.5, preferably greater than 2, more preferably greater than 3. The weak organic acid may be a dibasic or tribasic acid, and it may have at least one pK _a value in the range of 3 to 6. In one embodiment, the weak organic acid may be selected from the group consisting of citric acid, adipic acid, glycolic acid, and any combinations thereof. Preferably, the weak organic acid is citric acid.

The composition additionally contains a surfactant, preferably a nonionic surfactant. The concentration of surfactant in the composition may preferably be in the range of 2-25%, preferably 5-13%. Surfactant as described in this disclosure contains a hydrophilic head group and a hydrophobic tail group. Nonionic surfactants are surfactants with an uncharged hydrophilic head group and do not dissociate into ions in aqueous solutions. Preferred nonionic surfactants are ethoxylates, especially fatty alcohol ethoxylates, alkoxylates and cocamides. The surfactant useful for the present invention renders the components of the claimed composition miscible with each other, keeps them well dispersed, and forms a microemulsion. Surfactants can also increase the cleaning efficiency of the individual components of the composition.

In one embodiment, the surfactant may be selected from the group consisting of isotridecyl alcohol ethoxylate, dodecanol ethoxylate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated, polyethylene glycol trimethylnonyl ether, polysorbates , surfactants containing ethoxylated secondary alcohols and any combinations thereof.

Suitable dodecanol ethoxylates are nonionic surfactants containing one or more moles of ethylene oxide per mole of dodecanol. In some embodiments, the implementation of the molar ratio of ethylene oxide to dodecanol is 7: 1.

Suitable isotridecyl alcohol ethoxylates are nonionic surfactants containing one or more moles of ethylene oxide per mole of isotridecyl alcohol. In some embodiments, the molar ratio of ethylene oxide to isotridecyl alcohol is 9: 1.

Suitable polysorbates are nonionic surfactants composed of polyoxyethylene sorbitan fatty acid esters. Examples of polysorbates are polyoxyethylene sorbitan monolaurate, polysorbatesorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate.

In some embodiments, a suitable polyethylene glycol trimethylnonyl ether may be polyoxyethylene 2,6,8-trimethyl-4-nonyl ether.

The composition additionally contains a catalyst containing a divalent metal ion. In one embodiment, the concentration of the divalent metal ion containing catalyst in the composition may be in the range of 0.01-5%, preferably 0.25-3%. The divalent metal ion can be selected from the group consisting of Ca ⁺² , Mg ⁺² , Ba ⁺² , Fe ⁺² , Cu ⁺² , Ni ⁺² , Mn ⁺² and Co ⁺² , preferably Fe ⁺² , Ca ^{+ 2} , Cu ⁺² or Ni ⁺² . The origin of the effect that is achieved when the composition contains a catalyst containing a divalent metal ion is not yet fully understood. However, without wishing to be bound by any theory, it is assumed that either redox reactions or some chelating reactions may be involved.

The divalent metal ion containing catalyst may be in the form of a salt, where the counterion is any suitable organic or inorganic, divalent or monovalent anion, preferably citrate, acetate, maleate, sulfate or chloride, even more preferably sulfate or chlorate.

In one preferred embodiment, the composition comprises a solvent containing a glycol ether. The solvents containing glycol ether can be selected from the group consisting of solvents containing diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, polyethylene glycol monophenyl ether, and triethylene glycol monophenyl ether, and their monophenyl ethylene glycol ether. Preferably, the glycol ether solvent is selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and any combination thereof. The concentration of the solvent containing a simple glycol ether in the composition may be in the range of 0-15%, preferably 0.01-15%, more preferably 3-8%.

The compositions of the present invention remove moisture resistant resin contamination and / or prevent moisture resistant resins from contaminating papermaking equipment by removing, preventing, or reducing the formation of crosslinked chemicals from moisture resistant resins on papermaking equipment.

The cleaning composition can be diluted prior to use for cleaning papermaking equipment and contacted with said equipment. The diluent can be selected from the group consisting of water, compatible chemicals, compatible chemical mixtures or premixes, compatible liquids, compatible solids, or combinations thereof, preferably water. "Compatible" are those components that do not lead to separation between the components of the compositions and / or precipitation and maintain the microemulsion state of the composition during and / or after the addition and / or mixing of these components with the composition. According to one embodiment of the invention, the ratio of diluent / composition, based on weight / weight, is in the range of 500: 1-0: 1, preferably 200: 1-9: 1.

The composition is in contact with equipment, preferably papermaking equipment. Contact can be accomplished by spraying the composition onto the surface of the equipment, by soaking or immersing the equipment in the composition, or by introducing the composition into a circulating process stream that comes into contact with the equipment.

According to one embodiment of the invention, the cleaning is carried out at an elevated temperature. This means that the composition and / or equipment is at an elevated temperature during cleaning. Cleaning at elevated temperatures is accomplished by heating the cleaning composition or equipment to be cleaned, or both, at an elevated temperature prior to and / or during contact with each other. Cleaning compositions, or equipment to be cleaned, or both, are heated to temperatures from above room temperature to below 130 ° C, preferably from 45 to 70 ° C, more preferably from 50 to 60 ° C. In the preferred temperature range, an energy-optimized cleaning performance is observed.

The contact time depends on the area of the equipment to be cleaned, the type of equipment to be cleaned and / or the level of contamination of the equipment. The method of contact depends on the equipment to be cleaned. The contacting method can be soaking, spraying, or any other suitable contacting method as described above. Contact times are optimized so that optimal cleaning is achieved with minimal waste in production time. In some other embodiments, the contact time is from 0.1 second to 5 hours, preferably from 30 seconds to 1 hour, more preferably from 1 minute to 30 minutes.

The composition of the present invention is preferably used for cleaning papermaking equipment, especially papermaking equipment, containing impurities resulting from the use of wet resins in the papermaking process. The equipment to be cleaned is a wet press felt, drying mesh, or any papermaking equipment used in the papermaking process that uses wet resins or other papermaking surface. Preferably, the composition is used for cleaning wet press felts or drying nets.

The composition of the present invention is preferably used for cleaning stains caused by wet strength resin, especially when the wet strength resin is a polyamide epichlorohydrin (PAE) resin.

DEFINITIONS

The use of the word "a" or "an" in combination with the term "comprising" in the claims and / or in the description may mean "one", but it is also consistent with the meaning of "one or more", "at least one" and "One or more than one".

Throughout this document, the term "about" is used to mean that the value includes the standard deviation of the error for the device or method used to determine the value.

The use of the term “or” in the claims is used to mean “and / or” unless it is explicitly stated that it refers only to alternatives or alternatives are mutually exclusive, although the disclosure supports a definition that only refers to alternatives and “and / or”.

As used in this disclosure, the words "including" (and any form of inclusion such as "include" and "includes"), "having" (and any form of presence such as "have" and "has"), "including" (and any form of inclusion such as "include" and "includes") or "comprising" (and any form of content such as "contain" and "contains") are inclusive or open and do not exclude additional, unimplemented elements or method steps ...

The percentage of components in the compositions described herein is the weight percent of the components in the compositions. Mass percentages are calculated assuming the components are free of impurities.

EXAMPLES

The following examples as well as figures are included to demonstrate preferred embodiments of the invention. Those of skill in the art should understand that the methods disclosed in the examples or figures are methods found by the inventors that function well in the practice of the invention and, thus, can be considered as preferred modes of carrying out the invention. However, those skilled in the art should, in light of the present disclosure, understand that many changes can be made to the specific embodiments disclosed and still obtain a similar or similar result without departing from the spirit and scope of the invention.

Example 1: Cleaning Wet Press Felts

For the study, four sets of felt samples were used, each of which contained 2 samples. Circular felt samples about 2 inches (5 cm) in diameter were randomly cut from the bulk of the felt samples. Three sets were taken from a tissue and napkin paper mill (factory 1–3). The rest of the kit was primary cloth contaminated with PAE in the laboratory (VF). Circular cut virgin felt samples were soaked in PAE solution followed by heating in a 105 ° C oven for 2.5 hours to ensure cross-linking.

Each felt sample was washed and tested separately. A tergotometer was used to wash the felt samples. Loose fibers were collected between wash and rinse cycles. These harvested fibers were rolled into a small ball, dried, weighed, and recorded as "fiber loss" in the results. Results obtained for the removal of contaminants are corrected for fiber loss.

One felt sample from each set was washed with 5% (w / w) Composition A (Table 1). The composition was diluted with tap water. Another felt sample from each set was rinsed with tap water and used as a control for comparison. The felts were placed in separate washing containers and placed in a tergotometer. The tergotometer was run at 60 ° C for 30 minutes for the first wash step; The pH has been checked and recorded for each container. The contents of the container were then poured onto a vacuum sieve to collect felt and loose fiber samples. The samples and container were rinsed with tap water, and the samples were placed back into the container for a wash cycle at the same temperature for 15 minutes; The pH was checked and recorded for each container. Again the contents of these containers were poured onto a vacuum sieve to collect felt and loose fiber samples.

The weight of each felt sample was recorded before and after washing. Lost felt fibers were collected at the end of each wash and rinse cycle and weighed as a percentage of fiber loss. This percentage of fiber loss indicates how aggressive the chemical treatment of the felt was. The loss of fiber was partly due to the aggressiveness of the chemical treatment and partly because the felts were used in factories used in washing research and were not entirely new. After accounting for fiber loss, the remaining difference in felt between measurements before and after washing is attributed to the removal of contaminants and recorded as such. Ideally, chemical treatment removes large amounts of contaminant without causing too much fiber loss and damage to the felt. The percentage of contaminant removal and the percentage of fiber loss are shown in Tables 2 and 3, respectively, and are calculated as follows.

The porosity (or air permeability) test was carried out on the felt before and after washing using a Gurley precision porous tester with a digital timer. The test was carried out with air passing through an individual piece of cloth. A digital timer records the time that a controlled volume of air passes through the sample. The porosity before rinsing identifies any contamination of the felts that has blocked the pores of the felts. The post-wash test shows the porosity after targeted removal of the contaminant. Thus, comparison of porosity before and after flushing is indicative of overall removal of contaminants. The Gurley porosity was recorded in "Gurley seconds" and compared for the sample before and after washing. The fewer seconds of Gurley porosity, the more porous the felts are. Cleaner felts should have higher porosity, so fewer Gurley porosity seconds indicates better cleaning performance. The Gurley seconds of porosity are shown in Table 4.

The rate of water absorption on the felt before and after washing was also determined. 100 ml of fresh deionized water was added to a straight 8 oz (226.4 g) wide-mouth jar. The felt samples were flattened by hand and placed on the surface of the water using tweezers. The time between the initial contact of the felt with the water surface and the beginning of the immersion of the felt samples was recorded. As is often the case, the cloth can be too dirty (even after rinsing) and too hydrophobic to allow water to penetrate the fabric. If the test lasted more than 180 seconds, an excess of "> 180 s" or a "test of water absorption rate failed" was reported. This test helps determine how easily a felt sample will absorb water, how “open / loose” the felt was, and how hydrophilic or hydrophobic the felt was after comparing measurements before and after washing. Cleaner felts have a higher rate of water absorption (more open areas to absorb water because fewer pollutants trap those areas) and hence the water absorption time in seconds will be shorter. The water absorption time in seconds is shown in Table 5.

The results shown in Table 2 show that washing with 5% Composition A removed a significantly higher percentage of contaminants compared to the control. The results shown in Table 3 show that the percentage of fiber loss on washing with 5% Composition A was very low for all types of felts tested and was similar to that of the control. The results in Table 4 show that the porosity of the felts increased (Gurley porosity seconds decreased) more than the control by washing with 5% Composition A. The results in Table 5 show that the water uptake rate of the felts increased significantly (water uptake seconds decreased) compared to the control sample by washing with 5% composition A. Thus, composition A removes contaminants from the felts (tables 2, 4 and 5) without noticeable damage to the felts (table 3).

Example 2. Prevention of wet press felts contamination with moisture resistant resins.

Samples of primary felts about 2 inches (5 cm) in diameter were cut with a standard die cutter. Then one set of samples was placed in a 10% (w / w) aqueous solution of composition A, and the other set in water used as a control. The samples were soaked for five minutes at room temperature and dried overnight (16 hours) in an oven at 45 ° C. The moisture resistant chemicals, PAE, have been diluted using deionized water. The dried impregnated felts were placed in a diluted PAE solution (2.5% w / w) and soaked for five minutes at room temperature, then dried for 6.5 hours in a 45 ° C oven, and then crosslinked in an oven at 90 ° C for 4.5 hours. The felt was washed at 60 ° C in 600 ml of tap water for 30 minutes at 150 rpm in a tergotometer (Fig. 1). Fiber loss, porosity and water absorption rate were measured using the processes described in example 1. The percentage increase in mass was calculated as

The percent weight gain, fiber loss, Gurley porosity seconds and water uptake seconds are shown in Table 6. The percent weight gain for felt samples placed in a 10% aqueous solution of Composition A was lower compared to control felts (felts placed in water instead of 10% aqueous solution of composition A). The porosity and water absorption rate of the felts placed in a 10% aqueous solution of composition A were higher (Gurley porosity seconds and water absorption seconds less) compared to the control sample. These results show that Composition A prevents PAE resins from fouling felts. The percentage of fiber loss for felts placed in a 10% aqueous solution of Composition A was lower compared to the control. This shows that composition A does not damage the felt.

Table 1. Composition A

Mass% Water 61.5 Lemon acid 25 Isotridecyl alcohol ethoxylate (9 EO) 5 Diethylene glycol monobutyl ether 5 Carbowet GA – 211 (Air Products) 3 FeSO ₄ 0.5

Table 2 Removal of pollutants (%)

Factory 1 Factory 2 Factory 3 VF Wed A (5%) 1.03 2.16 1.81 1,032 Control 0.87 1.42 1.41 0.485

Table 3 Loss of fiber of the felt (%)

Factory 1 Factory 2 Factory 3 VF Wed A (5%) 0.83 0.76 0.68 0.97 Control 0.84 0.51 0.62 0.65

Table 4. Porosity according to Gurley (s)

Factory 1 Factory 2 Factory 3 VF Before flushing After rinsing Before flushing After rinsing Before flushing After rinsing Before flushing After rinsing Wed A (5%) 9.86 8.67 12.30 9.42 12.98 10.88 7.62 9.43 Control 9.98 9.52 14.73 13.17 13.43 11.81 7.62 10,00

Table 5. Water absorption rate (s)

Factory 1 Factory 2 Factory 3 VF Before flushing After rinsing Before flushing After rinsing Before flushing After rinsing After rinsing Wed A (5%) 11.82 3.54 3.30 2.64 > 180 7.76 5.06 Control 10.91 45.73 3.15 3.40 > 180 > 180 102.68

Table 6 Prevention of PAE crosslinking on primary felts

Compound Weight gain (%) Fiber loss (%) Gurley porosity (s) Water absorption (s) The average STDEV The average STDEV Control 2.73 0.74 8.15 0.42 319.310 * 14.22 Wed A (10%) 2.21 1.25 8.00 0.32 4.21 0.33

* For the control sample, the water absorption time test lasted more than 180 seconds.

Claims (26)

1. Application of a composition containing - an aqueous solution of a weak organic acid, - surface-active substance, - a catalyst containing a divalent metal ion, and - optionally, a solvent containing a simple glycol ether, for cleaning paper-making equipment from contamination with moisture-resistant resins, and these contaminants are formed when moisture-resistant resins are used in the papermaking process, where the wet strength resin is a polyamide epichlorohydrin (PAE) resin, by bringing the papermaking equipment into contact with said composition. 2. Use according to claim 1, wherein the organic acid is selected from the group consisting of citric acid, adipic acid, glycolic acid, and combinations thereof. 3. Use according to claim 1 or 2, wherein the surfactant is selected from the group consisting of isotridecyl alcohol ethoxylate, dodecanol ethoxylate, ethoxylated 2,4,7,9-tetramethyl-5-decyne-4,7-diol, simple polyethylene glycol trimethylnonyl ether, polysorbates, surfactants containing ethoxylated secondary alcohols, and their combinations. 4. Application according to any one of paragraphs. 1, 2 or 3, where the divalent metal ion is selected from the group consisting of Ca ⁺² , Mg ⁺² , Ba ⁺² , Fe ⁺² , Cu ⁺² , Ni ⁺² , Mn ^+2, and Co ⁺² . 5. The use according to any one of paragraphs. 1-4, where the solvent containing a simple glycol ether is selected from the group consisting of monobutyl ether of diethylene glycol, monoethyl ether of diethylene glycol, and combinations thereof. 6. Application according to any one of paragraphs. 1–5, where the concentration of organic acid is in the range of 10–45%; and / or the concentration of the solvent containing a simple glycol ether is in the range of 0-15; and / or the concentration of the catalyst containing the divalent metal ion is in the range of 0.01-5%, with the balance being water. 7. The use according to any one of paragraphs. 1-6 with diluent, where the diluent is selected from water. 8. Use according to claim 7, wherein the ratio of diluent / composition, weight / weight, is in the range of 500: 1–0: 1. 9. Use according to claim 1, wherein the composition and / or equipment is at an elevated temperature. 10. Use according to claim 1, wherein the contact time is between 0.1 second and 5 hours. 11. Use according to claim 10, wherein the contact time is from 30 seconds to 1 hour. 12. The use according to any one of paragraphs. 9-11, where the equipment is papermaking equipment, preferably wet press felts, papermaking equipment used in a papermaking process that uses wet resins, or other surface of a papermaking machine. 13. A method for preventing contamination of papermaking equipment with wet resins during the papermaking process, where the method includes the step of contacting the equipment with a composition comprising: - an aqueous solution of a weak organic acid, - surface-active substance, - a catalyst containing a divalent metal ion, and - optionally, a solvent containing a simple glycol ether, before, and / or during, and / or after the addition of wet-strength resin in the papermaking process, where the wet strength resin is a polyamide epichlorohydrin (PAE) resin.

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