CN1298988A - Paper made of aldehyde modified cellulose pulp contg. selecting additives - Google Patents
Paper made of aldehyde modified cellulose pulp contg. selecting additives Download PDFInfo
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- CN1298988A CN1298988A CN00129229A CN00129229A CN1298988A CN 1298988 A CN1298988 A CN 1298988A CN 00129229 A CN00129229 A CN 00129229A CN 00129229 A CN00129229 A CN 00129229A CN 1298988 A CN1298988 A CN 1298988A
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/16—Sizing or water-repelling agents
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
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Abstract
This invention relates to paper comprising aldehyde modified cellulose pulp prepared using nitroxyl radical mediated oxidation and further containing selected additives comprising aldehyde functional polymers or polymers containing functionality capable of reacting with aldehyde groups and having improved strength properties. This invention further relates to paper made from aldehyde modified cellulose pulp where an hydroxyl group containing polymer is added to the paper to provide wet strength properties.
Description
The present invention relates to paper comprising aldehyde modified cellulose pulp or fibers prepared under defined oxidation reaction conditions, said paper further comprising selected additives such that paper products having significantly improved dry and wet strength properties are obtained. More particularly, the invention relates to paper made from cellulose pulp modified by nitroxyl-mediated oxidation, said paper containing a polymer additive, said polymer containing functional groups capable of reacting with aldehydes, or being an aldehyde functional polymer. The present invention also relates to paper made from aldehyde modified cellulose pulp wherein hydroxyl containing materials are added to the papermaking operation to provide unexpected additional wet strength, dry strength and/or wet strength/dry strength ratio properties in the resulting paper product.
The term "paper" as used herein includes sheet-like substances or molded articles made from pulp or cellulosic materials derived from natural sources. Paper can also be made from synthetic cellulose fibers and regenerated cellulose and recycled waste paper. Also here, paper made of a combination of cellulosic and synthetic materials can be used. Paperboard is included within the scope of the term "paper".
As is generally known, paper is made by introducing an aqueous slurry of pulp or lignocellulosic fibers (which have been beaten or refined to a level at which the fibers can hydrate, or to which various functional additives may be added) onto a screen or similar device in a manner to remove water to form a sheet of consolidated fibers which can be processed into a dry paper roll or sheet by pressing and drying. Generally, in papermaking, the feed or feed to the papermaking machine is an aqueous slurry or suspension of pulp fibers, which is supplied by a so-called "wet end" system. At which the pulp and other additives are mixed in the aqueous slurry and subjected to mechanical or other operations, such as beating and refining. Various additives are often added to help provide different properties to the paper product.
The use of aldehyde functional additives (e.g., as wet and dry strength agents) in the paper industry is well known. For example, for the introduction of aldehyde groups into starch, both oxidative and non-oxidative methods are known. The use of products that provide dry and wet strength properties in papermaking includes the addition of such separate starch additive ingredients.
U.S. patent 5,698,688 issued on 16.12.1997 and to d.j. smith et al discloses aldehyde-modified cellulose fibers formed from esterified 1, 2-disubstituted alkenes which provide paper products having wet strength properties.
In a pending patent application serial No. 09/373,939, filed on 8/17/1999, a method for preparing aldehyde-modified cellulose pulp using selective oxidation conditions is described. In this patent application, aldehyde modified cellulose pulp products are described that can be used to prepare paper products with improved wet and dry strength properties.
Although the known processes for making paper described provide products with good dry and wet strength properties, there is a continuing need for paper products with further significant improvements in strength properties.
The present inventors have now found that paper comprising aldehyde-modified cellulose pulp made using defined nitroxyl oxidation conditions and comprising selected additives including polymers with functional groups capable of reacting with aldehydes or aldehyde functional polymers has significantly improved dry and wet strength properties.
More particularly, the present invention relates to aldehyde-modified cellulose pulp having improved dry and wet strength properties, wherein said pulp is prepared in an aqueous solution containing an oxidizing agent, wherein the oxidizing agent has an equivalent oxidizing power of up to 5.0g active chlorine per 100g cellulose and contains an effective mediating amount of nitroxyl radicals, and the reaction is carried out at a pH of about 8.0 to 10.5 and a temperature of about 5 to 50 ℃. The pulp further contains an effective amount of an additive comprising a polymer bearing functional groups capable of reacting with an aldehyde selected from the group consisting of hydroxyl, amino, amido, thiol, imide, and carboxylic acid groups or an aldehyde-functional polymer.
In another embodiment, the present invention relates to paper made from aldehyde modified cellulose pulp wherein hydroxyl containing materials are added to the paper making operation to achieve significantly improved wet strength, dry strength and/or wet strength/dry strength ratio properties in the resulting paper product.
The paper product of the present invention comprises aldehyde-modified cellulose pulp produced using defined nitroxyl-mediated oxidation conditions, said pulp further comprising selected additives comprising polymers with functional groups capable of reacting with aldehydes or aldehyde-functional polymers, to further improve wet strength, dry strength and/or wet strength/dry strength ratio performance.
The additive used in the present invention may be a polymer bearing functional groups capable of reacting with aldehydes, the additive comprising at least two aldehyde-reactive functional groups per polymer chain or molecule, in particular more than two aldehyde-reactive functional groups per polymer chain or molecule. More specifically, the aldehyde-reactive functional group-containing polymer has functional groups selected from hydroxyl, amino, amido, thiol, imino and carboxylic acid, or alkali metal, alkaline earth metal or ammonium salts thereof, or combinations thereof. Hydroxyl groups are most suitable.
The hydroxyl-containing additive polymer includes carbohydrates or polysaccharides such as starch, cellulose, gums and derivatives thereof. Hydroxyl-containing additive polymers include, for example, carbohydrate or polysaccharide polymers or modified carbohydrate polymers, such as starch or starch derivatives; guar gum or guar gum derivatives, such as hydroxypropyl guar hydroxypropyltriammonium chloride, hydroxyethyl cellulose, Polyquaternium-4, Polyquaternium-10, glucose or glucose derivatives, amylopectin or amylopectin derivatives, corn fiber gum or corn fiber gum derivatives, arabinogalactans or arabinogalactan derivatives, and locust bean gum; poly (vinyl alcohol) or copolymers of vinyl alcohol with other monomers, typically made by hydrolyzing copolymers of vinyl acetate with other monomers; and copolymers of hydroxyalkyl esters of acrylic or methacrylic acid, such as 2-hydroxyethyl methacrylate, with other copolymerizable monomers. Useful carbohydrate derivatives include cationic, anionic, amphoteric, ester and ether derivatives, with cationic and amphoteric derivatives being particularly suitable. It should further be noted that the hydroxyl-containing polymer may contain other substituents.
Examples of amino group-containing polymers include poly (vinylamine) or vinylamine copolymers (which are typically made by hydrolyzing copolymers of vinylformamide with other copolymerizable monomers), poly (ethyleneimine) and derivatives of poly (ethyleneimine), and chitosan.
Examples of the amide group-containing polymer include polyacrylamide, or a copolymer of other copolymerizable monomer with acrylamide, poly (vinylformamide) or vinylformamide copolymer, and poly (vinylacetamide) or vinylacetamide copolymer.
Examples of the imide group-containing polymer include poly (maleimide) and copolymers of maleimide with other copolymerizable monomers.
Polymers containing carboxylic acid functional groups or their alkali metal, alkaline earth metal or ammonium salts include homopolymers thereof or copolymers with the following other copolymerizable monomers: acrylic acid (or methacrylic acid) and its alkali metal, alkaline earth metal or ammonium salts, crotonic acid, dicarboxylic acid-containing monomers (e.g. maleic acid, fumaric acid and itaconic acid and their anhydrides), half esters of saturated dicarboxylic acids (e.g. methyl hydrogen fumarate, butyl hydrogen fumarate, ethyl hydrogen maleate, butyl hydrogen maleate) and their respective alkali metal, alkaline earth metal or ammonium salts.
The additives useful in the present invention may be aldehyde functional polymers, or more specifically, aldehyde functional polymers containing two or more aldehydes per polymer chain or molecule. Useful aldehyde-functional polymers include polysaccharide aldehydes of the general formula:
or Sacch-O-R9-CHO (Ⅳ)
Wherein "Sacch" denotes a polysaccharide molecule, such as starch, cellulose or gum; r is (CH)2)nOr a divalent aryl group, n is 0 or greater; r1、R6And R7Hydrogen, alkyl (especially methyl), aryl, aralkyl or alkaryl; r2、R5And R8Is (CH)2)mWherein m is 1 to 6, in particular 1 to 2; r3And R4Is hydrogen or lower alkyl, especially methyl; r9Is a divalent organic group containing a non-starch reactive substituent, and Y is an anion such as halide, sulfate or nitrate. Polysaccharide molecule can be used for treating diabetesModified by introducing cationic, anionic, nonionic, amphoteric and/or zwitterionic substituents.
Polysaccharide aldehyde derivatives Ito IV can be prepared by a non-oxidative process comprising: reacting the polysaccharide matrix with a derivatizing acetal reagent in the presence of a base. Further description of these aldehyde derivatives and their preparation is disclosed in U.S. patent 4,675,394 to d. solarek et al, published on 23.6.1987, which is incorporated herein by reference.
Other useful starch aldehyde derivatives include those produced by the selective oxidation of starch using limited amounts of an oxidizing agent and a nitroxyl mediator. These starch aldehyde derivatives can be prepared by the following method: oxidizing starch in an aqueous system with an oxidizing agent having an equivalent oxidizing power of up to 14.18g active chlorine per mole of starch anhydroglucose unit, and a nitroxyl radical in an amount effective to mediate oxidation of the starch, the reaction being carried out at a temperature of no more than about 15 ℃ and a pH of about 8.0 to 10.5. The starch aldehyde derivatives obtained contain up to 15 mole% of C-6 aldehyde groups per mole of starch anhydroglucose unit and have a minimum carboxylic acid content.
Other aldehyde derivatives that may be used as additives include starch and guar derivatives oxidized using enzymes including galactose oxidase as disclosed in the following references: germinio, us patent 3,297,604, published 10.1.1967, and c.chiu, us patent 4,663,448, published 5.5.1987. Preparation of dialdehyde starch by means of periodate oxidation of starch is disclosed in us patent 3,086,969 to j.e.slager published in 1963 on 4/23, and dialdehyde gum using periodate or periodic acid is disclosed in us patent 3,062,652 to r.jeffreys et al published in 1962. Other useful aldehyde-functional polymers or compounds include derivatives obtained by adding glyoxal to the poly (acrylamide) polymer and to the copolymer disclosed in U.S. patent 3,740,391 to l.williams et al, published 1973, 6-19, and derivatives obtained by reacting glyoxal and glutaraldehyde.
The aldehyde functional polymer additive may be used alone or with any of the polymer additives described above that contain a functional group capable of reacting with an aldehyde group. Also, polymer additives containing both aldehyde functional groups and functional groups capable of reacting with aldehyde groups may be used.
The additive polymer used in the present invention can be added to the oxidized pulp at any time during the papermaking process. Additive polymers with a net cationic charge are particularly useful if they are added at the wet end. Cationic charges can be introduced into these polymers by a number of different methods well known in the art. For example, if the additive is a polymer containing functional groups capable of reacting with an aldehyde, or an aldehyde-functional polymer made by free radical polymerization of copolymerizable monomers, positive charge can be introduced into the copolymer by copolymerizing cationic monomers such as (3-acrylamidopropyl) trimethylammonium chloride, [2- (acryloyloxy) ethyl]trimethylammonium sulfate, 2- (dimethylamino) ethyl acrylate, [3- (methacryloylamino) propyl]trimethylammonium chloride, [2- (methacryloyloxy) ethyl]trimethylammonium sulfate, 2- (dimethylamino) ethyl methacrylate, 2-aminoethyl methacrylate hydrochloride, diallyldimethylammonium chloride, vinylimidazole, and vinylpyridine, and substituted derivatives thereof. Additionally, positive charges can be introduced by reacting the additive polymer with a reagent bearing a positive charge, as described by d. Performance and application are described in chapter 8, "cationic starch" (1986), and in U.S. patent 4,119,487 to m.tessler, published 10.10.1978. The additives may also be sprayed or coated onto the wet web as a solution, dispersion or uncooked slurry.
The cellulose pulp aldehyde derivatives useful in the present invention may be prepared by a process involving nitroxyl-mediated oxidation. More specifically, the cellulose pulp aldehyde derivative is prepared by the following method: selective oxidation of cellulose and cellulose pulp or fibers using limited amounts of nitroxyl-mediated oxidizing agents under defined conditions yields derivatives with effective aldehyde content, making them particularly suitable for providing paper with desired wet strength, temporary wet strength and dry strength properties.
The nitroxyl mediator used here is a di-tert-alkyl radical of one of the following formulaeNitroxyl radical:
or
Wherein A represents a chain of specifically two or three atoms, in particular carbon atoms or a combination of one or two carbon atoms with oxygen atoms or nitrogen atoms; the R groups represent the same or different alkyl groups. Chain a may be substituted with one or more groups including alkyl, alkoxy, aryl, aryloxy, amino, amido or oxy; or may be substituted by a group which is linked, di-or polyvalent, to one or more other groups of formula I. Particularly useful nitroxyl radicals are di-tert-alkyl nitroxyl radicals of the formula:
wherein Y is H, OH or NH-CO-CH3Each R group represents identical or different alkyl groups containing from 1 to 18 carbon atoms, in particular methyl. Nitroxyl radicals of this type include: a) compounds in which all of the R groups are methyl (or alkyl having 1 carbon atom) and Y is H, i.e., 2,6, 6-tetramethyl-1-piperidinyloxy (TEMPO); b) compounds in which the R group is methyl and Y is OH, known as 4-hydroxy-TEMPO; and c) the R group is methyl and Y is NH-CO-CH3Known as 4-acetamido-TEMPO. Particularly suitable nitroxyl radicals are TEMPOor 4-acetylamino-TEMPO. The nitroxyl is used in an amount effective to mediate the oxidation reaction, more specifically about 0.001 to 20% (based on the weight percentage of cellulose, cellulose pulp or fibers), especially about 0.01 to 0.1%. Nitroxyl radicals can be added to the reaction mixture or generated in situ from the corresponding hydroxylamine or oxyammonium ion.
The oxidizing agent used in the present invention may be a substance capable of converting a nitroxyl group into the corresponding oxoammonium salt. Particularly useful oxidizing agents are alkali or alkaline earth metal hypohalites, such as sodium hypochlorite, lithium hypochlorite, potassium hypochlorite, or calcium hypochlorite. Alkali or alkaline earth metal hypobromite may also be used, either added as the hypobromite itself (e.g., sodium hypobromite) or generated in situ by the addition of a suitable oxidizing agent (e.g., sodium hypochlorite) and an alkali or alkaline earth metal bromide (e.g., sodium bromide). Bromide ions are typically generated as sodium bromide. Other oxidizing agents useful in the present process include hydrogen peroxide in combination with a transition metal catalyst, such as methyltrioxorhenium (vii); hydrogen peroxide in combination with an enzyme; oxygen in combination with a transition metal catalyst; oxygen bound to an enzyme; peroxy acids, such as peracetic acid and 3-chloroperoxybenzoic acid; alkali metal or alkaline earth metal peroxodisulfates, such as potassium peroxodisulfate and sodium peroxodisulfate; alkali metal or alkaline earth metal salts of monopersulfate, such as potassium monopersulfate; chloramines, such as 1,3, 5-trichloro-1, 3, 5-triazine-2, 4,6(1H,3H,5H) trione, 1, 3-dichloro-1, 3, 5-triazine-2, 4,6(1H,3H,5H) trione sodium salt, 1, 3-dichloro-5, 5-dimethylhydantoin, 1-bromo-3-chloro-5, 5-dimethylhydantoin, and 1-chloro-2, 5-pyrrolidinedione; and alkali or alkaline earth metal ferricyanidates. The list of oxidants herein is merely illustrative and not exhaustive. The oxidizing agent may be used alone or in combination with an alkali metal or alkaline earth metal bromide salt. A particularly suitable oxidizing agent is sodium hypochlorite or sodium hypobromite formed by the addition of sodium hypochlorite and sodium bromide.
An important factor in the use of an oxidizing agent is that the oxidizing agent must be used in a limited amount, which is an oxidizing agent of equivalent oxidizing power up to 5.0g of active chlorine per 100g of cellulose or cellulose pulp. More specifically, the amount of oxidizing agent used is an amount equivalent to about 0.05 to 5.0g of active chlorine equivalent oxidizing capacity per 100g of cellulose or cellulose pulp, and most preferably an amount equivalent to about 0.5 to 2.5g of active chlorine equivalent oxidizing capacity per 100g of cellulose or cellulose pulp. When sodium hypochlorite is used, it is used in an amount up to about 10% by weight of the cellulose or cellulose pulp, more specifically about 0.1 to 10%, most preferably about 1 to 5% by weight of the cellulose or cellulose pulp. The amount of bromide in the form of sodium bromide is generally from about 0.1 to 5%, especially from about 0.25 to 2% by weight of the cellulose or cellulose pulp. By limiting the amount of oxidizing agent under defined hydration conditions, cellulose aldehyde derivatives can be selectively prepared at effectively high aldehyde levels. The high aldehyde cellulose product is particularly useful for producing paper having wet strength, temporary wet strength, dry strength, and high wet strength/dry strength ratio properties.
The cellulosic material used as starting material may be any cellulose, cellulosic fibre or pulp material. They may include hardwood or softwood cellulose fibers, bleached or unbleached sulfate (Kraft) pulp, bleached or unbleached sulfite pulp, bleached or unbleached soda pulp, neutral sulfite pulp, semichemical pulp, groundwood, chemical groundwood, and any combination of these fibers. In addition, viscose synthetic cellulose fibers or regenerated cellulose types, as well as recycled waste paper from various sources, may also be used. The cellulose or pulp used has a consistency in water of about 0.1 to 15% by weight of solids in water, in particular about 1 to 5% by weight. When used in papermaking, other additives (such as desired inert fillers or retention aids) may be added to the cellulosic pulp. Such materials include clay, titanium dioxide, talc, calcium carbonate, calcium sulfate and diatomaceous earth. Rosin or synthetic internal sizes may also be included if desired.
The oxidation reaction of the cellulosic material is carried out in an aqueous solution. The reaction pH is maintained at about 8.0 to 10.5, in particular about 9 to 10; the temperature is maintained at about 5 to 50 deg.C, especially about 20 to 30 deg.C. The extent of the reaction is controlled by the amount of oxidant used or the reaction time. Generally, the reaction time is about 5 to 60 minutes, more specifically about 20 to 30 minutes.
By using the amounts of reagents and components and the reaction conditions as defined above, a controlled amount of aldehyde functionality (particularly C-6 aldehyde) can be obtained which is suitable to effectively provide the desired wet strength, temporary wet and dry strength properties and wet strength/dry strength ratio in the final paper product produced. The cellulose aldehyde derivatives prepared according to the present invention have an effective aldehyde functionality of about 1 to 20mmol, in particular about 5 to 20mmol per 100g of cellulosic material (i.e. cellulose or cellulose pulp). During the oxidation reaction, carboxylic acid functionality may also be produced or formed. The carboxyl content produced is generally from about 1 to 40mmol per 100g of cellulose or cellulose pulp, in particular from about 1 to 20mmol per 100g of cellulose or cellulose pulp, more in particular from about 1 to 10mmol per 100g of cellulose or cellulose pulp. It should be noted that the carboxylic acid functionality level should also add carboxylic acid functionality already present in the natural cellulose or cellulose pulp or imparted to the pulp by the processing method used (e.g. bleached sulphate or bleached sulphite, etc.). The effective amount of aldehyde is an important aspect of the present invention and one way to limit this amount is by controlling the ratio of aldehyde to carboxylic acid functionality produced. This content can be controlled by controlling the ratio of aldehyde to carboxylic acid produced to be greater than or equal to 0.5 (in terms of mmol of the respective functional groups of 100g of cellulose or cellulose pulp), in particular greater than or equal to 1.0. While it is recognized that other carboxylic acid functionalities (i.e., not generated) will vary and may be quite low, this is also an important factor and will affect the total carboxylic acid functionality level. In view of this, and based on the total carboxylic acid, the aldehyde to carboxylic acid functionality ratio is about 0.2 or greater. The importance of this particular aldehyde content can become particularly evident in the final properties of paper made from oxidized cellulosic material. The invention achieves high wet strength, temporary wet strength and dry strength properties. With these selectively modified aldehyde derivatives, products with high wet strength/dry strength ratios of greater than 20% can be obtained in paper, which is indicative of improved properties (e.g., softness).
In another embodiment of the present invention, hydroxyl group-containing polymers as previously described can be used with aldehyde-modified cellulose pulp to provide further improved wet and dry strength properties. This is very unexpected because it is not known that polymeric additives containing hydroxyl groups can provide wet strength properties to paper. Furthermore, by using such hydroxyl group-containing polymer additives together with oxidized cellulose pulp, the wet strength/dry strength ratio can be significantly improved. The improvement ratio is due to the percentage increase in wet strength being greater than the corresponding percentage increase in dry strength. The invention results in a product having a high temperature strength/dry strength ratio of greater than 25%. The aldehyde-modified cellulose pulp used in this embodiment may be pulp provided by any method including, but not limited to, the nitroxyl-mediated oxidation reaction described herein. Aldehyde-modified cellulose fibers are formed from esterified 1, 2-disubstituted alkenes disclosed in U.S. patent 5,698,688 to smith et al, published 12, 16, 1997.
It should be noted that the use of the modified aldehyde cellulose derivatives described herein in papermaking may involve the use of such derivatives as all or the entire pulp or papermaking stock, or as a component in the stock (i.e., in an amount of 20, 40, 60% by weight).
The proportion of additive polymer incorporated into the pulp can vary depending on the particular aldehyde-modified cellulose pulp involved and the performance requirements. In general, it is desirable to use from about 0.05 to 15% by weight, especially from about 0.1 to 5% by weight, of the additive, based on the weight of the dry pulp. Within this range, the exact amount used will depend on the type of pulp used, the particular operating conditions, and the end specific use of the paper.
Any desired inert inorganic filler may be added to the pulp containing the additive polymer of the present invention. Such materials include clay, titanium dioxide, talc, calcium carbonate, calcium sulfate, and diatomaceous earth. Other additives commonly added to paper, such as dyes, pigments, sizing additives (e.g. rosin or synthetic internal sizes), alum, anionic and cationic retention aids, microparticulate systems, etc., may also be added to the pulp.
The following examples will illustrate embodiments of the present invention in more detail. In these examples, all parts and percentages are by weight and all temperatures are in degrees Celsius, unless otherwise indicated. Further, when referring to the weight of the pulp, it refers to the weight of the pulp itself, i.e. the weight includes the equilibrium water content.
Example 1
Northern softwood kraft (nsk) pulp modification:
to 1600g of agitated NSK pulp suspension at a consistency of 3% (48g pulp) was added 4.8mg 4-acetamido-TEMP 0 and 0.24g sodium bromide (0.01% and 0.5% by weight of pulp (owp), respectively). The pH of the mixture was adjusted to 9.5 using 0.49N sodium hydroxide. All the sodium hypochlorite (7.93g, 12.1% solution, 2% owp) (the pH was also adjusted to 9.5 using concentrated HCl) was then added immediately and the mixture was stirred for 30 minutes at 25 ℃. The pH was measured using a Brinkmann pH meter 718Titrino, and the suspension pH was maintained at 9.5 throughout using 0.49N NaOH (6.8 ml). At the final stage of the treatment, the reaction was stopped by adding ascorbic acid to the mixture until its pH was reduced to the range of 4.0 to 4.5 (about 1 g).
The pulp was filtered and washed thoroughly with water adjusted to pH 4.5 to 5.5. And then repulped in water for use in the subsequent manufacture of handsheets, or dried in air for future use.
And (3) determining the aldehyde content in the modified paper pulp:
the aldehyde content of the modified NSK pulp was determined by hydroxylamine hydrochloride titration with the aid of an oxime derivatization reaction, as follows.
1200g of an aqueous suspension of oxidized pulp having a consistency of 2% were adjusted to pH 4 with aqueous HCl. To this mixture was added dropwise a large excess of 2M aqueous hydroxylamine hydrochloride (approximately 15 ml), the pH of which was adjusted to 4 with HCl. During the reaction, the pH was measured using a Brinkmann pH meter 718Titrino and the pH of the mixture was maintained at 4 by titration with 0.49N NaOH. Titration was continued until no further drop in the pH of the mixture was detected (approximately 1 hour). The aldehyde content was calculated from the total consumption of NaOH (4.1ml) as 8.4mmol/100g pulp using the following equation:
mmol/100g-CHO = ((NaOH titrant ml. times. NaOH equivalent concentration)/pulp weight g. times.) 100
Carboxylic acid content of modified pulp:
the amount of carboxylic acid generated during NSK pulp modification was calculated from the amount of NaOH titration (6.8ml of 0.49N solution) consumed to maintain the pH of the reaction. This provides a direct measurement of the formation of additional carboxylic acid in the pulp, which is 6.9mmol/100g pulp, calculated according to the following equation:
mmol/100g-COOH = ((NaOH titrant ml. times. NaOH equivalent concentration)/pulp weight g. times.) 100
Example 2
Hardwood pulp modification:
to 1600g of stirred hardwood pulp suspension at a consistency of 3% (48g pulp) was added 4.8mg of 4-acetamido-TEMPO and 0.24g of sodium bromide. The pH of the mixture was adjusted to 9.5 using 0.49N sodium hydroxide. All the sodium hypochlorite (7.93g, 12.1% solution, 2% owp) (the pH was also adjusted to 9.5 using concentrated HCl) was then added immediately and the mixture was stirred for 30 minutes at 25 ℃. The pH was measured using a Brinkmann pH meter 718Titrino, and the suspension pH was maintained at 9.5 throughout using 0.49N NaOH (6.8 ml). At the final stage of the treatment, the reaction was stopped by adding ascorbic acid to the mixture until its pH was reduced to the range of 4.0 to 4.5 (about 1 g). The pulp was filtered and washed thoroughly with water adjusted to pH 4.5 to 5.5. And then reslurried in water for use in the subsequent manufacture of handsheets, or air dried at room temperature for future use.
The aldehyde and carboxylic acid contents of the modified hardwood pulp were determined according to the method described in example 1 and were 7.7mmol and 4.3mmol per 100g pulp, respectively.
Example 3
Modified pulp samples (600 to 650 CSF) as described in examples 1 and 2 were made to 18 lb/3300 ft on a M/K Sheet Former at a consistency of 0.3% and a pH of 5 to 6 according to TAPPI Standard test method T2053And (4) making paper by hand. In a Waring blender, a wet end additive (0.5 to 1.0% cook-off or aqueous solution) is introduced into the pulp suspension and mixed for 30 seconds before sheet formation. The amount added may vary from 2.5 to 20 pounds per ton of pulp (lb/t), the specific amount added being given in the various examples. Conditioned handsheets (25 ℃ and 50% RH) were cut into ribbons (1' wide) and then tested for initial wet and dry tensile strength at the break point according to TAPPI Standard test methods T456 and 494.
Table 1 illustrates several cationic Starch-based polyhydroxy additives (CATO available from National Starch and chemical company) when used in combination with the aldehyde-modified softwood pulp described in example 1_232 and REDIBONtm5330A) Impact on paper strength properties.
TABLE 1
Effect of cationic starch-based polyhydroxy additives on paper Strength Properties based on aldehyde-modified NSK softwood pulp
| Paper pulp | Additive agent | Paper properties | |||
| NSK Cork wood | Cation(s) Starch | Amount of addition (lb/t) | High wet tensile strength Degree (g/in) | Dry tensile Strength (g/in) | Wet/dry ratio Example (%) |
| Unmodified | Is free of | 0 | 52 | 2158 | 2 |
| Unmodified | CATO 232* | 10 | 55 | 2392 | 2 |
| Modification of | Is free of | 0 | 632 | 2675 | 24 |
| Modification of | CATO 232* | 5 | 815 | 2758 | 30 |
| Modification of | CATO 232* | 10 | 866 | 3097 | 28 |
| Modification of | CATO 232* | 20 | 899 | 3114 | 29 |
| Modification of | 67WF QUAT Waxy* | 5 | 789 | 2787 | 28 |
| Modification of | 67WF QUAT Waxy* | 10 | 881 | 2895 | 30 |
| Modification of | 67WF QUAT Waxy* | 20 | 925 | 3084 | 30 |
| Modification of | REDIBOND 5330A* | 5 | 860 | 2943 | 29 |
| Modification of | REDIBOND 5330A* | 10 | 895 | 2824 | 32 |
| Modification of | REDIBOND 5330A* | 20 | 899 | 2989 | 30 |
*3-chloro-2-hydroxypropyltrimethylammonium chloride (QUAT) modified waxy corn starch;cationic nitrogen = 0.30%
The results clearly show that when cationic starch based polyols are used in combination with aldehyde and carboxylated modified softwood pulps, the dry-wet strength as well as the wet/dry strength ratio of the handsheets can be further improved.
Example 4
This example illustrates the general procedure described in example 3 for the preparation of cationic starchy polyols (CATO available from National Starch and Chemical Company)_232) Used as a dry and wet strength additive when used in combination with aldehyde modified hardwood pulp from example 2 (see table 2).
TABLE 2
Effect of cationic starch-based polyhydroxy additives on paper Strength Properties based on aldehyde-modified hardwood pulp
| Paper pulp | Additive agent | Paper properties | |||
| Hardwood | Cation(s) Starch | Amount of addition (lb/t) | High wet tensile strength Degree (g/in) | High dry tensile strength Degree (g/in) | Wet/dry ratio Example (%) |
| Is not changed Property of (2) | Is free of | 0 | 28 | 1343 | 2 |
| Is not changed Property of (2) | CATO 232* | 10 | 46 | 1429 | 3 |
| Modification of | Is free of | 0 | 292 | 1445 | 20 |
| Modification of | CATO 232* | 5 | 356 | 1563 | 23 |
| Modification of | CATO 232* | 10 | 378 | 1576 | 24 |
| Modification of | CATO 232* | 20 | 368 | 1677 | 22 |
*CATO 232: 3-chloro-2-hydroxypropyltrimethylammonium chloride-modified waxy corn starch; cationic nitrogen = 0.30%
The results clearly show that when cationic starch based polyols are used in combination with aldehydes and carboxylated modified hardwood pulp, the dry wet strength and wet/dry strength ratio of the handsheets can be further improved.
Example 5
This example illustrates the general procedure described in example 3 for the preparation of cationic Starch aldehydes (CO-BOND available from National Starch and Chemical Company)TM1000Plus starch) was used as a wet and dry strength additive in combination with the aldehyde modified softwood and hardwood pulps produced in examples 1 and 2 (see table 3).
TABLE 3
Effect of aldehyde-functional starch additives on paper Strength Properties based on aldehyde-modified pulp
| Paper pulp | Additive agent | Paper properties | |||
| Aldehyde starch | Amount of addition (lb/t) | High wet tensile strength Degree (g/in) | High dry tensile strength Degree (g/in) | Wet/dry ratio Example (%) | |
| NSK cork wood | |||||
| Unmodified | Is free of | 0 | 28 | 2171 | 1 |
| Unmodified | CO-BOND 1000Plus* | 10 | 346 | 2571 | 13 |
| Modification of | Is free of | 0 | 669 | 2558 | 26 |
| Modification of | CO-BOND 1000Plus* | 2.5 | 738 | 2600 | 28 |
| Modification of | CO-BOND 1000Plus* | 5 | 828 | 2926 | 28 |
| Modification of | CO-BOND 1000Plus* | 10 | 1009 | 3246 | 31 |
| Hardwood | |||||
| Unmodified | Is free of | 5 | 28 | 1343 | 2 |
| Unmodified | CO-BOND 1000Plus* | 10 | 240 | 1518 | 16 |
| Modification of | Is free of | 0 | 283 | 1343 | 21 |
| Modification of | CO-BOND 1000Plus* | 2.5 | 351 | 1462 | 24 |
| Modification of | CO-BOND 1000Plus* | 5 | 401 | 1597 | 25 |
| Modification of | CO-BOND 1000Plus* | 10 | 463 | 1698 | 27 |
*3-chloro-2-hydroxypropyltrimethylammonium chloride and 2-chloro-N- (2, 2-dimethoxyethyl) -N-methylacetamide modified waxy corn starch; cationic nitrogen = o.30% and acetaldehyde nitrogen = O.4%
The results clearly show that when cationic starch aldehydes are used in combination with aldehydes and carboxylated modified softwood and hardwood pulps, the dry-wet strength and wet/dry strength ratio of the handsheets can be further improved.
Example 6
This example describes according to the implementation 3The general procedure described above illustrates other polymers containing hydroxyl groups of cationic polysaccharides [ chitosan from Sigma Corporation, cationic Cellulose (CELQUAT) from National Starch and Chemical Company_H-100 derived cellulose resin, Polyquaternium-4) and cationic guar (3-chloro-2-hydroxypropyltrimethylammonium chloride modified guar; cationic nitrogen = o.30%)]Used as a dry and wet strength additive in combination with the aldehyde modified NSK softwood pulp prepared in example 1 (see table 4).
TABLE 4
Effect of cationic polysaccharide-containing hydroxyl polymers as additives on paper Strength Properties based on aldehyde-modified softwood pulp
| Paper pulp | Additive agent | Paper properties | |||
| NSK Cork wood | Polysaccharides | Amount of addition (lb/t) | Wet tensile strength (g/in) | Dry tensile Strength (g/in) | Wet/dry ratio Example (%) |
| Unmodified | Is free of | 0 | 29 | 2300 | 1 |
| Unmodified | Deacetylation Chitin | 10 | 72 | 2447 | 3 |
| Unmodified | Cation(s) Guar gum | 10 | 49 | 2527 | 2 |
| Unmodified | CELQUAT H-100 resin | 10 | 57 | 2101 | 3 |
| Modification of | Is free of | 0 | 608 | 2373 | 26 |
| Modification of | Deacetylation Chitin | 5 | 630 | 2479 | 25 |
| Modification of | Deacetylation Chitin | 10 | 646 | 2472 | 26 |
| Modification of | Cation(s) Guar gum | 5 | 737 | 2538 | 29 |
| Modification of | Cation(s) Guar gum | 10 | 662 | 2691 | 25 |
| Modification of | CELQUAT H-100 resin | 5 | 835 | 2537 | 33 |
| Modification of | CELQUAT H-100 resin | 10 | 841 | 2353 | 36 |
The results clearly show that when various polysaccharides are used in combination with aldehyde and carboxylated modified pulps, the dry-wet strength and wet/dry strength ratio of the handsheets can be further improved.
Example 7
Synthesis of poly (MAPTAC-co-DMA-co-HEMA) hydroxyl-containing trimer:
this example describes the synthesis of several of the following terpolymers for use with aldehyde-modified pulps as temporary wet strength additives: { poly [3- (methacrylamido) propyl]trimethylammonium chloride (MAPTAC) -co-N, N-Dimethylacrylamide (DMA) -co-2-hydroxyethyl methacrylate (HEMA) } trimer. The following procedure was used to synthesize trimer B (table 5). Similar procedures were used to prepare polymers A and C-K (Table 5) with different monomer amounts.
Directly above the four-necked round bottom flask was mounted a mechanical stirrer, two isobaric addition funnels (one of which was connected to the "Y" tap via a bypass tap and the other right side was connected to the "Y" tap), a thermometer and a nitrogen top inlet reflux condenser. To correct the purity of each component (50% MAPTAC, 99% DMA, 97% HEMA, 97% ammonium persulfate) monomers were weighed (0.63 g MAPTAC, 9.42g DMA, 2.53g HEMA in a beaker) anhydrous. The monomer mixture was then diluted with finished water to a total weight of 125 g. The solution was transferred to the addition funnel. A second addition funnel was then charged with a solution of ammonium persulfate prepared in a beaker using 125g of finished water to dissolve ammonium persulfate (0.06g, 0.5%). The two funnels are sealed at the top through a rubber diaphragm; purge with nitrogen for 20 minutes. Then, the feed comprising 25ml of monomer solution and 25ml of initiator solution was introduced into the reaction flask. After stirring the raw materials at 65 to 70 ℃ for 30 minutes, the monomer and initiator solutions were simultaneously added dropwise over a period of 1.5 hours while maintaining the temperature at 65 to 70 ℃ with an oil bath. After the slow addition was complete, the polymerization solution was held at 65 to 70 ℃ for a further 4 to 5 hours. The flask was then cooled to room temperature and the polymer varnish collected. For identification, a small portion of the lacquer was lyophilized. The conversion, concentration and molecular weight of the polymer were identified. The conversion of monomer to polymer was calculated by dissolving the lyophilized polymer in deuterium oxide (D2O) and performing 1H or 13C NMR spectroscopy. The concentration of the polymer (typically 5.0 to 5.5%) was determined by measuring the difference in weight of a small sample before and after heating at 105 ℃ for 1 hour on an electric furnace. The Inherent Viscosity (IV) (2.2 dl/g) was determined at 25 ℃ using 0.1g/100ml of polymer in 0.1N potassium chloride.
Table 5 lists a series of synthetic terpolymers varying the composition of MAPTAC, DMA and HEMA, and their effect as dry and wet strength additives with aldehyde modified softwood pulp.
TABLE 5
Use of hydroxy-functional synthetic copolymers as paper strength additives with aldehyde-modified softwood pulp
| Trimer component | Paper properties | ||||||
| Sample (I)* | MAPTAC (g) | DMA (g) | HEMA (g) | IV (dl/g) | High wet tensile strength Degree (g/in) | High dry tensile strength Degree (g/in) | Wet/dry ratio Example (%) |
| Modified cork paper pulp | 596 | 2462 | 24 | ||||
| A | 0.64 | 11.89 | 0 | 2.8 | 557 | 2383 | 23 |
| B | 0.63 | 9.42 | 2.53 | 2.2 | 539 | 2102 | 26 |
| C | 0.63 | 6.89 | 5.01 | 1.4 | 604 | 2112 | 29 |
| D | 1.25 | 11.28 | 0 | 2.6 | 594 | 2380 | 25 |
| E | 1.26 | 8.77 | 2.57 | 2.6 | 562 | 2208 | 25 |
| F | 1.26 | 6.25 | 5.01 | 1.0 | 610 | 2193 | 28 |
| G | 2.50 | 10.03 | 0 | 3.5 | 357 | 2212 | 16 |
| H | 2.52 | 7.51 | 2.51 | 2.1 | 538 | 2161 | 25 |
| I | 2.51 | 4.96 | 5.01 | 0.9 | 546 | 2294 | 24 |
| J | 5.05 | 7.50 | 0 | 2.6 | 293 | 2119 | 14 |
| K | 5.0 | 5.0 | 2.51 | 2.3 | 494 | 2341 | 21 |
*The mixture was used at 10 lb/t.
Example 8
This example illustrates the use of various synthetic polymers containing different aldehyde-reactive functional groups as dry and wet strength additives (see table 6) [ Cat-PVOH = cationic poly (vinyl alcohol) (available from Kuraray co. ltd., polymer CM-318), PAM = poly (acrylamide-co-diallyldimethylammonium chloride) (available from Aldrich), Polymin PR971L = poly (aziridine) (available from BASF)]when used in combination with the aldehyde-modified NSK softwood pulp prepared in example 1, according to the general procedure described in example 3.
TABLE 6
Effect of synthetic polymers containing various aldehyde-reactive functional groups as additives on paper Strength Properties based on aldehyde-modified softwood pulp
| Paper properties | ||||
| Additive agent | Amount of addition (lb/t) | High wet tensile strength Degree (g/in) | High dry tensile strength Degree (g/in) | Wet/dry ratio Example (%) |
| Is free of | 0 | 602 | 2421 | 25 |
| Cat-PVOH | 5 | 685 | 2231 | 31 |
| Cat-PVOH | 10 | 725 | 2313 | 31 |
| PAM | 10 | 683 | 2767 | 25 |
| Polymin PR971L | 10 | 675 | 2424 | 28 |
Example 9
This example describes the spray application of some hydroxyl functional additives to handsheets made from aldehyde modified softwood pulp. After making the handsheets according to the description of example 3, several 0.5 to 1% solutions of hydroxy-functional synthetic and natural polymers were applied to both sides of the handsheets by uniform spraying using a hand-held sprayer. The amount of polymer applied was calculated as the weight gain of the wet paper and the wet handsheet was air dried at room temperature. Then conditioned and tested according to the method described in example 3. The results are shown in Table 7. [ PVOH = poly (vinyl alcohol) (98% hydrolyzed, MV 124,000 to 186,000, available from Aldrich), Frodex 20= DE 20 maltodextrin (available from American Maize Corp.), Pullulan (available from Polysciences Corp.)].
TABLE 7
Spray application of hydroxy-functional polymers to handsheets made from aldehyde modified softwood pulps and their impact on strength properties
| Paper properties | ||||
| Additive agent | Amount of addition (lb/t) | Wet tensile strength (g/in) | Dry tensile Strength (g/in) | Wet/dry ratio (％) |
| Is free of | 0 | 594 | 2429 | 24 |
| Frodex 20 | 10 | 587 | 2571 | 23 |
| Frodex 20 | 20 | 571 | 2694 | 21 |
| PVOH | 6 | 654 | 2656 | 25 |
| PVOH | 12 | 726 | 3124 | 23 |
| PVOH | 20 | 752 | 3363 | 22 |
| Pullulan | 12 | 710 | 3151 | 23 |
| Pullulan | 20 | 725 | 2935 | 25 |
Claims (15)
1. In a process for making paper having properties of wet strength, temporary wet strength, dry strength, and high wet strength to dry strength ratio, the improvement comprising: aldehyde-modified cellulose pulp is used as a pulp stock prepared by oxidizing cellulose or cellulose pulp in an aqueous system with an oxidizing agent having an equivalent oxidizing power of up to about 5.0g of active chlorine per 100g of cellulose and a nitroxyl mediating effective amount of nitroxyl, and an effective amount of at least one additive comprising an aldehyde-functional polymer or a polymer containing functional groups capable of reacting with aldehyde groups is added.
2. The method of claim 1 wherein the aldehyde-reactive functional group in the additive polymer is selected from the group consisting of hydroxyl, amino, amido, thiol, imido and carboxylic acid, or an alkali metal, alkaline earth metal or ammonium salt thereof.
3. The method according to claims 1 to 2, wherein the aldehyde-reactive functional group is a hydroxyl group.
4. A process according to claims 1 to 3, wherein the oxidation reaction is carried out at a pH of about 8.0 to 10.5 and a temperature of about 5 to 50 ℃.
5. The method according to claims 1 to 4, wherein the cellulose pulp contains about 1 to 20mmol of aldehyde per 100g of cellulose.
6. A process according to claims 1 to 5 wherein the nitroxyl catalyst is a compound of the formula:
wherein Y is H, OH or NH-CO-CH3。
7. A process according to claims 1 to 6 wherein the aldehyde-reactive functional groups in the additive polymer are selected from hydroxyl, amino, amido, thiol, imino and carboxylic acids, or alkali metal, alkaline earth metal or ammonium salts thereof.
8. A process according to claims 1 to 7 wherein the aldehyde-reactive functional groups in the additive polymer are hydroxyl groups.
9. A process according to claims 1 to 8 wherein about 0.05 to 15% by weight of the additive is used, based on the dry weight of the pulp.
10. Paper made by the process of claims 1 to 9.
11. In a process for making paper having properties of wet strength, temporary wet strength, dry strength, and high wet strength to dry strength ratio, the improvement comprising: aldehyde-modified cellulose pulp is used as a pulp stock and an effective amount of a hydroxyl-containing polymer is added.
12. The method according to claim 11, wherein the hydroxyl containing polymer is a carbohydrate selected from the group consisting of starch, cellulose and gum.
13. The method of claims 11 to 12 wherein about 0.05 to 15% by weight of the additive is used based on the dry weight of the pulp.
14. A method according to claims 11 to 13 wherein the carbohydrate is a derivative selected from the group consisting of cationic, anionic, amphoteric, ester and ether containing derivatives.
15. Paper made by the process of claims 11 to 14.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/454,400 | 1999-12-03 | ||
| US09/454,400 US6368456B1 (en) | 1999-08-17 | 1999-12-03 | Method of making paper from aldehyde modified cellulose pulp with selected additives |
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| CN1298988A true CN1298988A (en) | 2001-06-13 |
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| CN00129229A Pending CN1298988A (en) | 1999-12-03 | 2000-09-30 | Paper made of aldehyde modified cellulose pulp contg. selecting additives |
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|---|---|
| JP (1) | JP2001207395A (en) |
| KR (1) | KR20010060227A (en) |
| CN (1) | CN1298988A (en) |
| AR (1) | AR026156A1 (en) |
| BR (1) | BR0004719A (en) |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108864980A (en) * | 2018-08-06 | 2018-11-23 | 合肥龙发包装有限公司 | A kind of corrugated paper adhesive enhancing additive |
| CN112218930A (en) * | 2018-04-04 | 2021-01-12 | 索理思科技公司 | Application of strength additive foam aid to paper products |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1907623B1 (en) * | 2005-05-02 | 2012-04-25 | International Paper Company | Ligno cellulosic materials and the products made therefrom |
| US20100043990A1 (en) * | 2006-11-23 | 2010-02-25 | Nederlandse Organisatie Voor Toegepastnatuurwetens | Biopolymers as wet strength additives |
| CN113226741B (en) | 2018-11-02 | 2023-06-16 | 巴科曼实验室国际公司 | Synthesis of repulpable temporary wet strength polymers for consumer paper applications |
| CN114395937B (en) * | 2022-01-18 | 2023-04-18 | 齐鲁工业大学 | Efficient solar photo-thermal evaporation paper and preparation method thereof |
-
2000
- 2000-08-31 AR ARP000104558A patent/AR026156A1/en unknown
- 2000-09-18 CA CA002319998A patent/CA2319998A1/en not_active Abandoned
- 2000-09-30 CN CN00129229A patent/CN1298988A/en active Pending
- 2000-10-09 BR BR0004719-8A patent/BR0004719A/en not_active Application Discontinuation
- 2000-10-19 JP JP2000318871A patent/JP2001207395A/en active Pending
- 2000-10-31 KR KR1020000064170A patent/KR20010060227A/en not_active Application Discontinuation
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112218930A (en) * | 2018-04-04 | 2021-01-12 | 索理思科技公司 | Application of strength additive foam aid to paper products |
| CN112218930B (en) * | 2018-04-04 | 2023-11-14 | 索理思科技公司 | Auxiliary application of strength additive foam to paper products |
| CN108864980A (en) * | 2018-08-06 | 2018-11-23 | 合肥龙发包装有限公司 | A kind of corrugated paper adhesive enhancing additive |
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| Publication number | Publication date |
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| KR20010060227A (en) | 2001-07-06 |
| AR026156A1 (en) | 2003-01-29 |
| MXPA00011232A (en) | 2002-03-15 |
| CA2319998A1 (en) | 2001-06-03 |
| JP2001207395A (en) | 2001-08-03 |
| BR0004719A (en) | 2001-09-25 |
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