阅读说明：本技术 造纸工艺中化学效率的提高 (Chemical efficiency enhancement in papermaking process ) 是由 J·C·哈林顿 M·罗 D·E·沙洛颜 S·辛格 于 2018-10-02 设计创作，主要内容包括：一种在造纸系统中提高化学添加剂的化学效率的方法,其包括以下步骤：提供浓纸浆,所述浓纸浆包括可溶性木质素、工艺用水和基于浓纸浆的总重量至少约2重量％的纤维素纤维,并添加至少一种漆酶和至少一种有机聚合物到浓纸浆中以减少其中可溶性木质素的量。所述有机聚合物选自阳离子聚合物、非离子聚合物及其组合。(A method of increasing the chemical efficiency of a chemical additive in a papermaking system comprising the steps of: providing a thick pulp comprising soluble lignin, process water, and at least about 2 wt% of cellulosic fibers based on the total weight of the thick pulp, and adding at least one laccase enzyme and at least one organic polymer to the thick pulp to reduce the amount of soluble lignin therein. The organic polymer is selected from the group consisting of cationic polymers, nonionic polymers, and combinations thereof.)

1. A method of increasing the chemical efficiency of a chemical additive in a papermaking system, the method comprising the steps of:

providing a thick pulp comprising soluble lignin, process water, and at least about 2 wt% of cellulosic fibers, based on the total weight of the thick pulp, and

adding at least one laccase and at least one organic polymer to the thick pulp to reduce the amount of soluble lignin therein;

wherein the organic polymer is selected from the group consisting of cationic polymers, nonionic polymers, and combinations thereof.

2. The method of claim 1, wherein the thick pulp comprises at least about 3 wt% of the cellulosic fibers based on the total weight of the thick pulp, and wherein the cellulosic fibers are derived from NSSC pulp, OCC pulp, deinked pulp, virgin fiber, mechanical pulp, unbleached kraft pulp, or a combination thereof.

3. The method of claim 1 or 2, wherein the organic polymer is cationic and has the general formula II:

[B-co-C](II)

wherein B is one or more nonionic repeating units formed after polymerization of one or more nonionic monomers, C is one or more different cationic repeating units formed after polymerization of one or more cationic monomers, and-co-means that the polymer is a copolymer of B and C.

4. The method of claim 3, wherein the B: C molar percentage of the nonionic monomer of formula II to the cationic monomer is from about 99: 1 to about 50: 50.

5. The method of any one of claims 1-4, wherein the organic polymer has general formula III:

[-C-]

wherein C is one or more different cationic repeat units formed after polymerization of one or more cationic monomers.

6. The method of any one of claims 1-4, wherein the organic polymer is selected from the group consisting of cationic polyacrylamides, polyvinylamines, polyethyleneimines, diallyldimethylammonium chloride polymers, trialkylaminoalkyl (meth) acrylamide polymers, epichlorohydrin-dimethylamine copolymers, polyethylene oxide polymers, polyethylene oxide-polypropylene oxide copolymers, polyoxazolines, and combinations thereof.

7. The method of claim 6, wherein the cationic polyacrylamide is derived from at least one monomer selected from the group consisting of: diallyldimethylammonium chloride, N-trialkylaminoalkyl (meth) acrylates, N-trialkylaminoalkyl (meth) acrylamides, epichlorohydrin dimethylamine, and combinations thereof.

8. The method of any one of claims 1-7, wherein the cationic polymer comprises a polyvinylamine derived from at least one monomer selected from the group consisting of: n-vinylformamide, N-vinylmethylformamide, N-vinylphthalimide, N-vinylsuccinimide, N-vinyl-tert-butyl carbamate, N-vinylacetamide, and combinations thereof.

9. The method of claim 1 or 2, wherein the organic polymer is a polymer dispersion comprising (i) a high molecular weight cationic polyacrylamide having a weight average molecular weight of greater than about 1,000,000g/mol and (ii) a low molecular weight cationic dispersant polymer derived from greater than about 50 wt% cationic monomer and having a weight average molecular weight of from about 100,000 to about 500,000 g/mol.

10. The method of claim 1 or 2, wherein the nonionic or cationic polymer has a weight average molecular weight of from about 100,000 to about 10,000,000 Da.

11. The method of claim 1 or 2, wherein the organic polymer is non-ionic and has a weight average molecular weight of about 1,000,000 to about 10,000,000 Da.

12. The method of claim 1 or 2, wherein the organic polymer is a polyethylene oxide polymer having a weight average molecular weight of greater than about 1,000,000Da and less than about 10,000,000 Da.

13. The method of claim 1 or 2, wherein the organic polymer is a cationic polyacrylamide having a weight average molecular weight of greater than about 200,000 and less than about 10,000,000 Da.

14. The method of any one of claims 1 to 13, wherein the laccase is added to the process water in an amount of from about 0.01 pounds to about 1.0 pounds per ton of dried pulp.

15. The method of any one of claims 1 to 14, wherein the organic polymer is added to the process water in an amount of about 0.05 to about 5 dry pounds of organic polymer per ton of dried pulp.

16. The method according to any one of claims 1 to 15, wherein the reduction in the amount of soluble lignin in the process water is evidenced by at least a 5% reduction in the absorbance in the UV-VIS spectrum measured at about 280nm after 24 hours as compared to process water without the at least one laccase and at least one organic polymer.

17. The method of any one of claims 1-16, wherein the chemical oxygen demand of the process water is reduced by at least about 5% as compared to the chemical oxygen demand of the process water without the at least one laccase and the at least one organic polymer.

18. The method of any one of claims 1 to 17, further comprising the step of adding an inorganic coagulant to the process water, wherein the inorganic coagulant is selected from the group consisting of aluminum sulfate, aluminum chloride, aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate, ferric chloride (III), ferric sulfate (III), ferrous chloride (II), ferrous sulfate (II), ferrous polysulfate, and combinations thereof.

19. A method of increasing the chemical efficiency of a chemical additive in a papermaking system, the method comprising the steps of:

providing a thick pulp comprising soluble lignin, process water, and at least about 2 wt% of cellulosic fibers, based on the total weight of the thick pulp, and

adding at least one laccase and at least one inorganic coagulant to the thick pulp to reduce the amount of soluble lignin therein.

20. The method of claim 19, wherein the inorganic coagulant is selected from the group consisting of aluminum sulfate, aluminum chloride, aluminum chlorohydrate, polyaluminum chloride, polyaluminum sulfate, ferric chloride (III), ferric sulfate (III), ferrous chloride (II), ferrous sulfate (II), ferrous polysulfate, and combinations thereof.

Technical Field

The present disclosure relates to a method for increasing the efficiency of chemical additives in a papermaking system. More specifically, the method reduces the amount of soluble lignin in process water of a papermaking system by using a laccase and a second component.

Background

The proposed solution meets the paper manufacturers' needs of maximizing the efficiency of chemical additives in various systems such as highly or fully enclosed recycled cardboard plants, minimizing fresh water consumption, and minimizing wastewater discharge the problem of additive chemical efficiency decline is common, the scarcity of fresh water resources and the increasing cost of using fresh water and discharging wastewater have prompted paper manufacturers to reduce fresh water consumption and recover process water, today, many recycled cardboard (R L B) plants consume 5 cubic meters or less of fresh water per 1 ton of paper produced.

The amount of impurities dissolved in water can multiply and cause many problems in paper making. These problems include deposit formation, increased odor, and high levels of VFA, COD, and conductivity. The increased levels of dissolved and colloidal components compromise the efficiency of chemical additives such as strengthening, retention and drainage polymers, sizing agents, and the like. Therefore, the papermaker must increase the consumption of chemical additives. However, at some point, the increased polymer loading does not help to achieve the desired performance, especially in fully enclosed paper mills.

Primary paperboard mills, while consuming more fresh water than recycle paperboard mills, still face the same problem of reduced chemical efficiency. In many raw paperboard mills, chemical additives do not work well, in some cases even at all.

The efficiency of chemical additives such as retention and drainage polymers, dry strength additives, sizing agents and wastewater treatment polymers will increase with the removal of anionic impurities, more specifically with the removal of soluble lignin species.

In addition to cellulose and hemicellulose, lignin is also one of the main components of wood. Lignin is a natural, highly aromatic and hydrophobic polymer. For the production of printing grade paper, most of the lignin is decomposed and removed from the cellulose by kraft pulping. The extra amount of lignin is further reduced by a series of bleaching and washing steps. However, for producing paper packaging grades, other pulp sources are used. These include virgin pulp, mechanical pulp, semichemical mechanical pulp, and recycled fibers, such as OCC (old corrugated containers), and the like. These low-grade pulps may contain significant amounts of lignin.

Paper makers have used polymers or enzymes and combinations thereof to improve the quality of the paper produced, such as dry strength polymers. For example, US 9,663,899B 2 describes compositions for papermaking applications comprising a laccase, a lipase and a cationic immobilization polymer, and optionally a laccase activator. The patent teaches increasing dry strength by applying enzymes and polymers to the lignocellulosic fibers.

US 8,454,798B 2 describes a process for making paper or paperboard by applying a composition comprising an enzyme and a cationic coagulant to the papermaking pulp prior to paper formation to typically improve drainage, retention, or both the predominant enzyme is cellulase.

US 2014/0116635 a1 describes the application of enzymes and polymers comprising at least one cationic water-soluble polymer and an amphoteric water-soluble polymer or both to papermaking pulp. The list of enzymes includes cellulases and laccases or both. The list of polymers includes Glyoxalated Polyacrylamide (GPAM), polyvinylamine (PVAm), decarboxylated polyacrylamide or dimethylamine-epichlorohydrin (EPI-DMA) or combinations thereof. The results of the enzyme-polymer treatment are an increase in dry strength as measured by the Ring Crush Test (RCT) and the Corrugating Medium Test (CMT).

Disclosure of Invention

The present disclosure addresses the problem of soluble dissolved colloidal lignin in plant process water by enzymatic and polymerization methods. The present disclosure more specifically provides a method of increasing the chemical efficiency of chemical additives in a papermaking system. The method comprises the following steps: providing a thick pulp comprising soluble lignin, process water, and at least about 2 wt% of cellulosic fibers, based on the total weight of the thick pulp, and adding at least one laccase and at least one organic polymer to the thick pulp to reduce the amount of soluble lignin therein. Further, the organic polymer is selected from the group consisting of cationic polymers, nonionic polymers, and combinations thereof.

The present disclosure also provides another method of increasing the chemical efficiency of a chemical additive in a papermaking system. The method comprises the following steps: providing a thick pulp comprising soluble lignin, process water, and at least about 2 wt% of cellulosic fibers, based on the total weight of the thick pulp, and adding at least one laccase enzyme and at least one inorganic coagulant to the thick pulp to reduce the amount of soluble lignin therein.

Drawings

Fig. 1 is a graph depicting the removal of soluble lignin by application of laccase, Perform PK2320 polymer products, and combinations thereof.

Fig. 2 is a graph depicting the removal of soluble lignin by applying laccase, Perform PK2320 polymer products, and combinations thereof at low doses.

Fig. 3 is a graph depicting removal of soluble lignin by application of laccase, Zalta MF300 polymer products, and combinations thereof.

Figure 4 is a graph depicting removal of soluble lignin by application of xylanase and Perform PK2320 and combinations thereof.

Figure 5 is a graph depicting drainage times in treated (laccase/Perform PK2320, 0.25/1.0 lb/ton addition to thick pulp) and untreated filtrates with and without filter aid Hercobond 5475.

Fig. 6 is a graph depicting drainage test data for samples treated with thick stock laccase and then with thin stock polymer with and without thick stock treatment with a laccase/polymer combination.

Detailed Description

A method of removing soluble lignin in a papermaking system is disclosed. The new process allows for the chemical efficiency of papermaking additives including strength additives, retention and drainage polymers, sizing agents, etc. The present disclosure discloses a novel method for removing soluble lignin from thick pulp in a papermaking process. The method comprises adding a laccase together with a second component to the thick pulp, which second component may be, for example, a cationic or nonionic polymer and/or an inorganic coagulant. The method can include adding a cationic or nonionic polymer to the thick stock of a papermaking system in a highly closed papermaking system. The reduction of lignin from thick pulp and its fixation on the fibers results in a significant increase in the efficiency of chemical additives, including the efficiency of reinforcing agents, sizing agents, retention and drainage aids.

As the degree of water shut-off increases due to regulatory restrictions or water shortage, the efficiency of the chemical additives decreases. The decrease in chemical efficiency, and in some cases the complete loss of polymer additive performance, is generally attributed to organic contaminants, a widely defined substance in plant process waters, collectively referred to as anionic impurities. Anionic impurities generally include very short fibers, referred to as fines; degraded starch; degraded or modified chemical additives such as polymers and soluble dissolved colloidal lignin. These components affect the properties of chemical additives differently, in particular cationic polymers. Applicants have investigated the effect of several troublesome components on cationic polymers based on component analysis of several commercially recovered virgin kraft and NSSC paper mills using a model white water system. Lignin, while not the most prevalent species in plant process waters, has the greatest adverse impact on chemical efficiency.

Soluble lignin is a very delicate component in the dissolution and colloidal components of paper process water. Soluble lignin is found to have a range of molecular weights. As the molecular weight decreases, its tendency to absorb on the fiber and to be removed from the system decreases (J.Sundin and N.Hartler in Nordic Pulp and Paper Research Journal, v.5No 4,2000, p 306. sub.312 concluded that the low molecular weight lignin (<1000Da) did not precipitate at all). As a result, over time and with increasing cycle times, low molecular weight soluble lignin species accumulate in the process water, resulting in reduced performance of the polymer additive.

The present disclosure addresses the problem of soluble lignin in thick pulp by enzymatic and polymerization processes. Soluble lignin can be removed from paper making process water by a process comprising adding laccase and nonionic and/or cationic polymers to the thick stock.

Non-ionic polymers useful in the present disclosure include, but are not limited to, polyoxazoline, polyethylene oxide (PEO), polyethylene oxide copolymers or copolymers of Polypropylene Oxide (PO), copolymers of polyethylene oxide and polypropylene oxide (EO/PO), polyvinylpyrrolidone, Polyethyleneimine (PEI), and/or combinations thereof PEO can be a homopolymer of ethylene oxide, or a copolymer of ethylene oxide and propylene oxide and/or butylene oxide homopolymers of polyethylene oxide are most common examples of such products are available from Solenis LL C (Wilmington, DE) in form PB 8714 and from Dow Chemical (Midland, MI) in the form of a dry powder product of Ucarfloc 300, 302, 304, and 309 PEO homopolymers can also be available in the form of a slurry in which PEO is dispersed in a medium that can be any one or more of ethylene glycol, propylene glycol, poly (ethylene glycol), poly (propylene glycol), glycerol, and the like, and/or combinations thereof examples of PEO slurries include willebra C3000 from Solenis LL C (r z).

Nonionic or cationic polymers useful in the present disclosure may be of the following formula I or II or III.

B represents one or more different nonionic repeating units formed after polymerization of one or more nonionic monomers.

C represents one or more different cationic repeating units formed after polymerization of one or more cationic monomers.

The nonionic polymer segment B in formulas I and II is a repeating unit formed after polymerization of one or more nonionic monomers. Exemplary monomers that can be used in the B coverage of the present disclosure include, but are not limited to, acrylamide; (ii) methacrylamide; n-alkylacrylamides, such as N-methylacrylamide; n, N-dialkylacrylamides, such as N, N-dimethylacrylamide; methyl methacrylate; methyl acrylate; acrylonitrile; n-vinylmethylacetamide; n-vinylformamide; n-vinylmethylformamide; vinyl acetate; n-vinyl pyrrolidone, and mixtures of any of the foregoing. The present disclosure contemplates that other types of nonionic monomers may also be used, or that more than one nonionic monomer may be used. The nonionic monomers preferably used are acrylamide; (ii) methacrylamide; n-vinylformamide.

The cationic polymer segment C in formulas II and III is a repeating unit formed after polymerization of one or more cationic monomers. Exemplary monomers encompassed by C useful in the present disclosure include, but are not limited to, cationic ethylenically unsaturated monomers, such as diallyl dialkyl ammonium halides, such as diallyl dimethyl ammonium chloride; (meth) acrylic esters of dialkylaminoalkyl compounds, such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, 2-hydroxydimethylaminopropyl (meth) acrylate, aminoethyl (meth) acrylate and salts and quaternary ammonium salts thereof; n, N-dialkylaminoalkyl (meth) acrylamides, such as N, N-dimethylaminoethylacrylamide, and salts and quaternary ammonium salts thereof, and mixtures thereof. The most common are diallyldimethylammonium chloride (DADMAC) and dimethylaminopropyl (meth) acrylamide (dimpa), dimethylaminoethyl (meth) acrylate (ADAME) and its salts and quaternary ammonium salts and mixtures thereof.

Another method of preparing the cationic polymers of structure II is to polymerize the monomers, followed by hydrolysis. The degree of hydrolysis can be expressed in terms of "percent hydrolysis" or "percent hydrolysis" on a molar basis. Thus, a hydrolyzed polymer may be described as "% hydrolyzed". Furthermore, the degree of hydrolysis may be approximate. For the purposes of applicants' disclosure, reference to a "50% hydrolyzed" polyvinylamine is a reference to about 40% to about 60% hydrolyzed. Likewise, a polyvinylamine that is about 100% hydrolyzed means about 80 to about 100% hydrolyzed. The hydrolysis reaction results in the conversion of some or all of the monomer to amine, as controlling the hydrolysis reaction can vary the percentage of monomer resulting having amine functionality. Polyvinylamines can be used in the present invention. Examples of monomers useful in preparing polyvinylamines include, but are not limited to, N-vinylformamide, N-vinylmethylformamide, N-vinylphthalimide, N-vinylsuccinimide, N-vinyl-tert-butyl carbamate, N-vinylacetamide, and mixtures of any of the foregoing. Most commonly polymers prepared by hydrolysis of N-vinylformamide. In the case of copolymers, nonionic monomers, such as those described above, are common comonomers. Alternatively, the polyvinylamine may be prepared by derivatizing a polymer. Examples of such methods include, but are not limited to, the hofmann reaction of polyacrylamide. It is contemplated that other synthetic routes may be used to synthesize polyvinylamines or polyamines.

Polymer dispersions, such as those described in U.S. patent 7323510, which is expressly incorporated herein by reference in its various non-limiting embodiments, may be used in the present disclosure. For example, a dispersion comprising (i) a high molecular weight cationic polyacrylamide having a weight average molecular weight greater than about 1,000,000, and (ii) a high charge (derived from greater than about 50%, typically about 60%, of cationic monomer), low molecular weight cationic dispersant polymer having a molecular weight between about 100,000 and about 500,000 can be used in the present disclosure. Typical cationic monomers for the dispersion components are those listed for polymer segment C. All values and ranges of values and values included between the above values are expressly contemplated for use herein in various non-limiting embodiments.

B of a nonionic monomer and a cationic monomer of formula II: the C mole percent may fall between about 99: 1 to about 1:99, or about 80:20 to about 20:80, or about 75:25 to about 25:75 or about 40:60 to about 60:40 or about 99: in the range of 1 to 50:50, most typically about 99: 1 to about 90:10, wherein the mole percentages of B and C add up to about 100%. It is to be understood that more than one nonionic or cationic monomer may be present in formula II or III. All values and ranges of values and values included between the above values are hereby expressly contemplated for use herein in various non-limiting embodiments.

The cationic or nonionic polymers used in the present disclosure can be manufactured and provided to the end user in the form of a dry or granular powder, an aqueous solution, a dispersion, or an inverse emulsion.

The molecular weight of the cationic or nonionic polymer can be from about 100,000 to about 10,000,000Da, typically greater than about 250,000. The molecular weight of the cationic or nonionic polymer can be from about 400,000 to about 10,000,000 Da. Generally, higher molecular weight nonionic polymers provide more efficient removal of soluble lignin. For example, when a nonionic polymer or dispersion polymer is used, the molecular weight is typically about 1,000,000 or greater. For highly charged (greater than 60% cationic monomer) cationic polymers (DADMAC or dimpa or EPI-DMA), the molecular weight can range from about 100,000 up to about 1,000,000, or typically from about 200,000 up to about 500,000. Generally, for low charge cationic polymers (10 mole% or less cationic monomer), the molecular weight can be from about 1,000,000 up to about 10,000,000 Da. All values and ranges of values and values included between the above values are hereby expressly contemplated for use herein in various non-limiting embodiments.

The dosage of the nonionic or cationic polymer can be from 0.01 to 10 pounds of polymer solids (e.g., reactive organic polymer) per ton of dried pulp (e.g., dry furnish solids), or from about 0.01 to about 10 pounds, or from about 0.05 to about 5 pounds, or from about 0.1 to about 3 pounds, or from about 0.1 to about 2 pounds of polymer solids (e.g., reactive organic polymer) per ton of dried pulp (e.g., dry furnish solids). All values and ranges of values and values included between the above values are hereby expressly contemplated for use herein in various non-limiting embodiments.

It has been found that the removal of soluble lignin from thick pulp can be synergistically enhanced by adding a laccase and a nonionic or cationic polymer to the thick pulp. Theoretically, laccases catalyze the polymerization and oxidative coupling of low molecular weight soluble lignin to higher molecular weight species, thereby making soluble lignin complexation and removal by cationic or nonionic polymers more effective.

The removal of soluble lignin can be further enhanced by combining laccase with inorganic cationic coagulants such as polyaluminum chloride, alum (aluminum sulfate), aluminum chlorosulphate, aluminum chlorohydrate, iron (III) chloride, iron (III) sulfate, iron (II) chloride, iron (II) sulfate, ferrous polysulfate and any other aluminum or iron based cationic coagulants known to those skilled in the art. The inorganic cationic coagulant may be added in an amount of about 0.01 to about 12 pounds dry solids per dry fiber solids, or more specifically, about 0.05 to about 6 pounds dry solids per dry fiber solids. All values and ranges of values and values included between the above values are hereby expressly contemplated for use herein in various non-limiting embodiments.

Laccases are enzymes from the oxidoreductase family, which are known to catalyze the oxidation and/or crosslinking of soluble lignin and other aromatic structures. It can be hypothesized that polymerization of smaller soluble lignin fragments with oxidoreductases, such as laccases, will promote the binding of higher molecular weight soluble lignin to cellulose fibers, resulting in an overall reduction of soluble lignin in the thick pulp. In addition, it can be hypothesized that higher molecular weight soluble lignin will also have a higher affinity for cationic polymers, and thus, the use of laccase together with cationic or nonionic polymers can synergistically increase the efficiency of soluble lignin removal from plant water.

The laccase used in the present application may be of microbial, fungal or plant origin, and may or may not be used with a mediator, a compound that promotes or maintains enzyme efficiency, in order to obtain higher efficiency, it requires the presence and influx of oxygen to catalyze the oxidation and crosslinking of aromatic structures, particularly structures associated with soluble lignin, the amount of laccase added may be from about 0.01 pounds to about 5.0 pounds of product, more particularly from about 0.01 to about 1.0 pounds or from about 0.1 pounds to about 1.0 pounds per ton of dried pulp (e.g., dry furnish solids), where one pound of laccase product corresponds to about 500,000L AMU units, 1L AMU is defined as the amount of enzyme that oxidizes 1mmol syringaldazine per minute at standard conditions (pH 7.5, 30 ℃).

Laccases work most efficiently at a pH of about 5 to about 9, more typically about 6 to about 8, and a temperature of about 15 ℃ to about 75 ℃, more typically about 35 ℃ to about 55 ℃. All values and ranges of values and values included between the above values are hereby expressly contemplated for use herein in various non-limiting embodiments.