KR20010060227A - Paper made from aldehyde modified cellulose pulp with selected additives - Google Patents

Abstract

PURPOSE: Provided is a 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. CONSTITUTION: The method of making paper having wet strength, temporary wet strength, dry strength and high wet strength/dry strength ratio properties contains: using an aldehyde modified cellulose pulp as the pulp stock which is prepared by oxidizing cellulose or cellulose pulp in an aqueous system with an oxidant having an equivalent oxidizing power of up to about 5.0g of active chlorine per 100g of cellulose and a mediating effective amount of nitroxyl radical; and adding an effective amount of at least one additive comprising aldehyde functional polymers or polymers containing functional groups capable of reacting with aldehyde groups.

Description

Paper made from aldehyde modified cellulose pulp containing optional additives {PAPER MADE FROM ALDEHYDE MODIFIED CELLULOSE PULP WITH SELECTED ADDITIVES}

The present invention relates to papermaking, which comprises aldehyde-modified cellulose pulp or fiber prepared using defined oxidation conditions, and further contains optional additives which provide significantly improved wet and dry strength properties for papermaking products. . More specifically, the present invention relates to papermaking, which is prepared from cellulose pulp modified by nitrooxy radical-mediated oxidation and which contains additives comprising polymers or aldehyde functional polymers having functional groups capable of reacting with aldehydes. . The present invention also provides aldehyde-modified cellulose pulp that provides more than expected wet, dry and / or wet / dry strength ratio properties to paper products obtained by adding hydroxyl group-containing materials to the papermaking process. It is about the papermaking that is made.

As used herein, the term "papermaking" refers to sheet-like materials and shaped articles made from pulp or fibrous cellulose materials that can be derived from natural raw materials. In addition, paper can be made from synthetic cellulose fibers and recycled cellulose, as well as recycled waste paper, paper made from a mixture of cellulosic materials and synthetic materials is also included in the scope of paper herein, and paperboard is also a broad term "papermaking. It is included in the meaning of ".

As is commonly known, papermaking uses a water-based slurry of pulp or wood cellulose fibers (which may be beaten or refined and added with various functions to achieve the level of hydration of the fibers) in a manner that removes water. It is prepared by injection into a screen or similar device into a consolidated fibrous sheet, followed by compression and drying in the form of a dry roll or sheet. Typically, the material that is fed or injected into the papermaker in papermaking is an aqueous slurry or water suspension of pulp fibers fed from a system called a “wet end”. In the wet zone, the pulp is mixed with other additives into an aqueous slurry and subjected to mechanical or other operational processes such as beating and refining. In general, various additives are added to provide different properties to paper products.

The use of aldehyde action additives as wet strength agents and dry strength agents in the paper industry is well known in the art. For example, as a method of introducing an aldehyde group into starch, an oxidation method and a non-oxidation method are widely known. These products, which are used to provide wet and dry strength properties in papermaking, are added as individual starch additive components.

U.S. Patent No. 5,698,688 to DJ Smith et al. On November 16, 1997, describes aldehyde-modified cellulose fibers made from esterified 1,2-disubstituted alkenes useful for providing paper products with wet strength properties. .

Pending Application No. 09 / 373,939, filed on August 17, 1999 and concurrently with this application, describes a process for preparing aldehyde-modified cellulose pulp using selective oxidation conditions. In this application, aldehyde modified cellulose pulp products have been described as useful for making paper products having improved wet strength and dry strength properties.

While the known papermaking methods described above provide good wet strength and dry strength properties, there is a continuing need for paper products having significantly improved strength properties.

The present invention is to provide a papermaking product having improved wet strength and dry strength properties.

The present inventors include aldehyde modified cellulose pulp prepared using defined nitroxy oxidation conditions and further contain optional additives comprising polymers or aldehyde functional polymers containing functional groups capable of reacting with aldehydes. Has been found to have significantly improved wet strength and dry strength properties.

More specifically, the present invention relates to an aldehyde-modified cellulose pulp having improved wet strength and dry strength properties, wherein the aldehyde-modified cellulose pulp is an oxidizing agent and mediate effective amount having an oxidation power equivalent to 5.0 g or less of active chlorine per 100 g of cellulose. A polymer or aldehyde functional polymer prepared in an aqueous solution containing a nitrooxy radical of which contains a functional group capable of reacting with an aldehyde selected from the group consisting of hydroxy, amino, amido, thiol, imide, and carboxylic acid groups. It further contains an effective amount of an additive including. The reaction is carried out at a pH of about 8.0 to 10.5 and a temperature of about 5 to 50 ℃.

In another embodiment, the present invention provides aldehyde modifications that provide significantly improved wet strength, dry strength, and / or wet strength / dry strength ratio properties to paper products obtained by adding hydroxy group-containing materials to the papermaking process. It relates to cellulose pulp.

The papermaking product of the present invention comprises an aldehyde-modified cellulose pulp prepared using the prescribed nitroxy-mediated oxidation reaction conditions, which further improves the ratio properties of improved wet strength, dry strength, wet strength / dry strength and It further contains optional additives, including polymers or aldehyde functional polymers containing functional groups that can react.

The additive used in the present invention may be a polymer containing a functional group capable of reacting with an aldehyde and will contain at least two aldehyde reactive functional groups, in particular two or more aldehyde reactive functional groups per polymer chain or molecule. More specifically, the aldehyde reactive functional group in the polymer will be selected from the group consisting of hydroxy, amino, amido, thiol, imido, and carboxylic acid groups, or from their alkali, alkaline earth or ammonium salts, or mixtures thereof. . Especially, a hydroxyl group is the most suitable.

Additive polymers having hydroxyl groups include carbohydrates or polysaccharides such as starch, cellulose, gums, and derivatives thereof. Examples of the additive polymer having a hydroxyl group include carbohydrates such as starch or starch derivatives, polysaccharide polymers, or modified carbohydrate polymers; Hydroxypropyl Guar Hydroxypropyltrimonium Chloride, Hydroxyethyl Cellulose, Polyquaternium-4, Polyquaternium-10, Dextran or Dextran Derivatives, Pullulan or Pullulan Derivatives, Corn Fiber Gum or Corn Fiber Gum Derivatives Derivatives of guar gum or guar gum, such as arabinogalactan or arabinogalactan, and locust bean gum; Poly (vinyl alcohol), or copolymers of vinyl alcohol and other monomers, typically prepared by hydrolysis of copolymers of vinyl acetate and other monomers; And copolymers of hydroxy alkyl esters of acrylic or methacrylic acid with other copolymerizable monomers such as 2-hydroxyethyl methacrylate. Useful carbohydrate derivatives include cation, anion, and zwitterion, ester and ether derivatives, with cationic and zwitterionic derivatives being particularly preferred. The hydroxyl group-containing polymer may contain other substituents.

Examples of polymers having amino groups are poly (vinyl amine) or vinyl amine copolymers, which are typically copolymers of vinyl formamide and other copolymerizable monomers, derivatives of poly (ethylene imine) and poly (ethylene imine), and It is prepared by hydrolysis of chitosan.

Examples of polymers having amido groups include acrylamide copolymers containing poly (acrylamide) or other copolymerizable monomers, poly (vinyl formamide) or vinyl formamide copolymers, and poly (vinyl acetamide) or vinyl acetamide Copolymers.

Examples of imido-containing polymers are poly (maleimide) and copolymers of maleimide with other copolymerizable monomers.

Polymers containing carboxylic acid functional groups or their alkali, alkaline earth, or ammonium salts include other copolymerizable monomers of (meth) acrylic acid and their alkali, alkaline earth, or ammonium salts; Crotonic acid; Dicarboxylic acid-containing monomers such as maleic acid, fumaric acid, and itaconic acid and their anhydrides; Homopolymers or copolymers containing half esters of unsaturated dicarboxylic acids such as methyl hydrogen fumarate, butyl hydrogen fumarate, ethyl hydrogen malate and their respective alkali, alkaline earth or ammonium salts.

The additive used in the present invention may be an aldehyde functional polymer, in particular an aldehyde functional polymer containing at least two aldehydes per polymer chain or molecule. Useful aldehyde functional polymers include polysaccharide aldehydes having the general formula:

or

In the above formula, sugar means polysaccharide molecule such as starch, cellulose, or gum; R is (CH ₂ ) _n or a divalent aromatic group and n is an integer of 0 or more; R ₁ , R ₆ , and R ₇ are selected from the group consisting of hydrogen atom, alkyl (particularly methyl), aryl, aralkyl, or alkaryl group; R ₂ , R ₅ , and R ₈ are (CH ₂ ) _m , m is an integer from 1 to 6, in particular from 1 to 2; R ₃ and R ₄ are hydrogen or lower alkyl, in particular methyl; R ₉ is a divalent organic group containing no starch reactive substituents; Y is an anion such as halide, sulfate, or nitrate. Polysaccharide molecules can be modified by the introduction of cation, anion, nonionic, amphoteric ions, and / or zwitterionic substituents.

Polysaccharide aldehyde derivatives (I) to polysaccharide aldehyde derivatives (IV) can be prepared by a non-oxidation method comprising the reaction of a polysaccharide base with an acetal reactant in the presence of an alkali. Such aldehyde derivatives and preparation methods are described in US Pat. No. 4,675,394 to D. Solarek et al. On June 23, 1987, which is incorporated herein by reference.

Other useful starch aldehyde derivatives include those prepared by selective oxidation using limited amounts of oxidizing agents and nitroxy radical mediators. Such starch aldehyde derivatives can be prepared by oxidizing starch in an aqueous system containing an oxidizing agent having an oxidizing power equivalent to or less than 14.18 g of active chlorine per unit mole of starch anhydrous glucose and an intermediary effective amount of nitroxy radicals. And at a temperature of about 15 ° C. or less and a pH of about 8.0 to 10.5 or less. The resulting starch aldehyde derivative may have up to 15 mol% C ₆ aldehyde groups and trace carboxylic acid content per unit mole of starch anhydrous glucose.

Other aldehyde derivatives that may be used as additives are galactose described in US Pat. No. 3,297,604, issued to F. Germino on January 10, 1967, and US Pat. No. 4,663,448, issued to C. Chiu on May 5, 1987. Starch and guar gum derivatives which are oxidized by enzymes such as oxidants. U.S. Patent No. 3,086,969, issued to JE Slager on April 23, 1963, describes a dialdehyde starch prepared by oxidizing starch using peroxonic acid, and on November 6, 1962 to R. Jeffreys et al. United States Patent No. 3,062,652 discloses dialdehyde gums using peracetic acid or peracetic acid. As described in US Pat. No. 3,740,391 to L. Williams et al. On June 19, 1973, glyoxal and glutaraldehyde as well as those prepared by adding glyoxal to poly (acrylamide) polymers and copolymers Useful as aldehyde functional polymers or compounds.

The aldehyde functional polymer additive may be used alone or in combination with any polymer additive containing a functional group capable of reacting with an aldehyde group as described above. It is also possible to use polymer additives containing aldehyde functional groups and functional groups capable of reacting with aldehyde groups.

The additive polymer used in the present invention may be added to the oxidized pulp at any time in the papermaking process. When these additive polymers are added to a wet part, the additive polymer which has a net positive charge is especially preferable. Positive charge can be introduced into such polymers or other materials by a variety of methods known in the art. For example, when the additive is a polymer or an aldehyde functional polymer containing a functional group capable of reacting with an aldehyde made by free radical polymerization of the copolymerizable monomer, (3-acrylamidopropyl) trimethyl ammonium chloride, [2- (acryloxy) ethyl] trimethylammonium methyl sulfate, 2- (dimethylamino) ethyl acrylate, [3- (methacryloylamino) propyl] trimethylammonium chloride, [2- (methacryloyloxy) Of cationic monomers such as ethyl trimethylammonium methyl sulfate, 2- (dimethylamino) ethyl methacrylate, 2-aminoethyl methacrylate hydrochloride, diallyldimethylammonium chloride, vinyl imidazole and vinyl pyridine, and substituted derivatives thereof A method comprising copolymerization can be used to introduce a positive charge in the copolymer. In addition, the positively charged reactants and active polymers are described in D. Solarek's Modified Starches: Properties and Uses , "Cationic Starches" in Chapter 8 and US Patent No. 4,119,487 to M. Tessler, issued October 10, 1978. A positive charge can also be introduced by making it react. In addition, the additive may be sprayed or applied to the wet web as a solution, dispersion, or uncooked slurry.

The cellulose pulp aldehyde derivatives used in the present invention can be prepared by a method comprising nitrooxy-mediated oxidation. More specifically, the cellulose pulp aldehyde derivative is added to nitrooxy radicals under defined conditions to provide derivatives having an effective amount of aldehyde content that are particularly suitable for providing paper with the desired wet strength, temporary wet strength, and dry strength properties. It can be prepared by a method of selectively oxidizing cellulose and cellulose pulp or fibers using a limited amount of oxidizing agent mediated by.

Nitrooxy radical mediators used in the present invention are di-t-alkyl nitrooxy radicals having one of the formula:

or

Wherein A is 2 or 3 atoms, in particular a carbon atom chain, or a mixed chain of 1 or 2 carbon atoms and oxygen or nitrogen atom, and R group is preferably the same or different alkyl group. Chain A may be substituted with one or more groups, such as alkyl, alkoxy, aryl, aryloxy, amino, amido, or oxo groups, or with divalent or polyvalent groups bonded to other groups of formula (I). . Particularly useful nitrooxy radicals are di-t-alkyl nitrooxy radicals having the formula:

Wherein Y is H, OH, or NH-C (o) -CH ₃ and each R group is the same or different alkyl group, in particular a methyl group, consisting of 1 to 18 carbon atoms. Nitrooxy radicals of this type include:

a) 2,2,6,6-t-methyl-1-piperidinyloxy (TEMPO) wherein all R groups are methyl (or C1 alkyl) and Y is H;

b) 4-hydroxy-TEMPO wherein R group is methyl and Y is OH;

c) 4-acetamido-TEMPO wherein the R group is methyl and Y is NH-C (O) -CH ₃ .

Particularly preferred nitroxy radicals are TEMPO or 4-acetamido-TEMPO. The nitroxy radical is used in an amount effective to mediate oxidation, preferably in an amount of about 0.001 to 20% by weight, more preferably about 0.01 to 0.1% by weight, based on the weight of the cellulose, cellulose pulp or fiber. Nitrooxy radicals can be added to the reaction mixture or generated at the position used from the corresponding hydroxyamine or oxoammonium ions.

The oxidant used in the present invention may be any material capable of converting nitrooxy radicals to the corresponding oxoammonium salts. Particularly useful oxidizing agents are alkali or alkaline earth hypohalogens such as sodium hypochlorite, lithium hypochlorite, potassium hypochlorite, or calcium hypochlorite. Alkali or alkaline earth hypobromite may be used, which may be added in the form of hypobromite itself, such as sodium hypobromite, or by adding an appropriate oxidizing agent such as alkali or alkaline earth bromide, such as sodium hypobromite and sodium bromide It can also be created at the location used. Bromine ions are usually in the form of sodium bromide. Additional oxidants that can be used in this process include, but are not limited to: hydrogen peroxide mixed with transition metals such as methyltrioxorenium; Hydrogen peroxide mixed with enzymes; Oxygen mixed with transition metal catalysts; Oxygen mixed with enzymes; Peroxy acids such as peracetic acid and 3-chloroperoxybenzoic acid; Alkali or alkaline earth salts of sulfites, such as potassium sulfite and sodium sulfite; Alkali or alkaline earth salts of peroxymonosulfate, such as potassium peroxymonosulfate; 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 Chloramines such as -2,5-pyrrolidinedione; And alkali or alkaline earth salts of ferricyanide. The oxidant may be used alone or in admixture with bromide of alkali or alkaline earth. Preferred sodium hypochlorite or sodium hypochlorite is sodium hypobromite formed at the position used by the addition of sodium bromide.

An important point in the use of oxidizing agents is that they must be used in limited amounts with an oxidizing power equivalent to up to 5.0 g of active chlorine per 100 g of cellulose or cellulose pulp. In particular, the oxidizing agent is used in an amount having an oxidizing power equivalent to about 0.05 to 5.0 g of active chlorine, preferably about 0.5 to 2.5 g of active chlorine per 100 g of cellulose or cellulose pulp. When sodium hypochlorite is used, it is used in a limited amount of up to about 10% by weight, preferably about 0.1 to 10% by weight, more preferably about 1 to 5% by weight, based on the weight of the cellulose or cellulose pulp. Bromide in the form of sodium bromide is generally used in an amount of about 0.1 to 5% by weight, preferably about 0.25 to 2% by weight, based on the weight of cellulose or cellulose pulp. Cellulose aldehyde derivatives can optionally be prepared to contain aldehydes at high effective levels by limiting the amount of oxidant under defined aqueous conditions. Such cellulose products having a high aldehyde content are particularly useful for the production of paper having a property of ratio of wet strength, transient wet strength, dry strength, and wet strength / dry strength.

The cellulosic material used as starting material may be any cellulose, cellulose fiber or pulp material. Such materials include bleached and unbleached sulphate (Kraft), bleached and unbleached sulfite, bleached and unbleached soda, neutral sulfite, semi-chemical ground wood, chemical ground wood, and these There are hardwood or softwood cellulose fibers, such as mixtures of fibers, and recycled paper from various raw materials as well as synthetic cellulose fibers or regenerated cellulose of viscose rayon may be used. The concentration of cellulose or pulp used in the aqueous solution is about 0.1 to 15% by weight, preferably about 1 to 5% by weight, in solids content in water. When used in papermaking, other additives such as desired inert fillers or retention aids may be added to the cellulose pulp. Such materials include clay, titanium dioxide, talc, calcium carbonate, calcium sulfate, and diatomaceous earth. Rosin or synthetic internal size can also be used if desired.

Oxidation of the cellulosic material is carried out in an aqueous solution. The pH of the reaction is maintained at about 8.0 to 10.5, preferably about 9 to 10 and the reaction temperature is maintained at about 5 to 50 ° C, preferably about 20 to 30 ° C. The degree of reaction is controlled by the amount of oxidant used or the reaction time. In general, the reaction time is about 5 to 60 minutes, preferably about 20 to 30 minutes.

By using the reaction reagents and the component contents as described above and the prescribed reaction conditions, the desired wet strength and dry strength properties including the desired wet strength, the temporary wet strength, and the compressive and compressive resistance of the finally produced paper product Adequate and effective controlled amounts of aldehyde functional groups, in particular C-6 aldehydes, can be obtained that are suitable for providing a ratio of dry strength. The cellulose aldehyde derivatives prepared according to the invention will contain about 1 to 20 mmol, preferably about 5 to 20 mmol of effective aldehyde functional groups per 100 g of cellulose material, ie cellulose or cellulose pulp. Carboxylic acid functional groups will also be produced or formed during the oxidation process. The amount of carboxyl groups produced will be about 1 to 40 mmol, preferably about 1 to 20 mmol, more preferably about 1 to 10 mmol, per 100 g of cellulose or cellulose pulp. This content of carboxylic acid functionality is in addition to what may be present in existing cellulose or cellulose pulp and may vary depending on the type of processing pulp used, such as bleach sulphate, bleach sulfite and the like. An effective amount of aldehyde may be defined as the ratio of aldehyde to carboxylic acid functional groups produced as an important aspect of the present invention. This content can be defined when the ratio of aldehyde to carboxylic acid produced is at least 0.5 mmol, preferably at least 1.0 mmol (based on 100 g of cellulose or cellulose pulp of each functional group). The amount of carboxyl functional groups added (ie carboxyl functional groups other than those produced) may vary and can be very low, although small amounts will be present and this value will affect the total content of carboxylic acid functional groups. In view of this, the ratio of aldehyde to carboxylic acid functionality will be about 0.2 or greater. The importance of the aldehyde content is particularly pronounced in the properties of papermaking made from oxidized cellulosic materials, with a high dry strength including wet strength, temporary wet strength, and compressive and compressive resistance. Making paper using selectively modified cellulose aldehyde derivatives exhibiting improved properties such as ductility yields products having a wet strength / dry strength ratio of at least 20%.

In another embodiment of the present invention, the hydroxy group-containing polymer described above can be used with any aldehyde modified cellulose pulp to provide improved wet strength and dry strength properties. This is particularly unexpected because it was not known that hydroxy group-containing polymer additives provide wet strength properties to papermaking. Moreover, the use of such hydroxyl group-containing polymer additives with cellulose oxide pulp significantly improves the ratio of wet strength / dry strength. This improved rate is due to the large increase in wet strength compared to the corresponding increase in dry strength. A product having a high wet strength / dry strength ratio of at least 25% is obtained. Aldehyde-modified cellulose pulp used in this example may be, but is not limited to, pulp prepared by any method including the nitroxy radical-mediated oxidation described herein. Aldehyde-modified cellulose fibers can be prepared from esterified 1,2-disubstituted alkenes described in US Pat. No. 5,698,688, issued December 16, 1997 to D. J. Smith et al.

The modified aldehyde cellulose derivative of the present invention may be used as a derivative such as complete pulp or whole pulp or paper stock solution in the manufacture of paper, or may be used as one component (ie, 20, 40, 60% by weight, etc.) of the paper stock solution.

The proportion of the additive polymer mixed in the paper pulp can vary depending on the particular aldehyde modified cellulose pulp used and the desired properties. Generally, it is preferable to use about 0.05 to about 15% by weight of additives, particularly preferably about 0.1 to 5% by weight, based on the dry weight of the pulp. Within this range, the exact content used will depend on the type of pulp used, the particular operating conditions, and the end use of the paper.

Preferred optional inert mineral fillers may be added to the pulp containing the additive polymer of the present invention. Such materials include clays, titanium dioxide, calcium carbonate, calcium sulfate, and diatomaceous earth. For example, sizing additives such as dyes, pigments, rosin or synthetic internal sizes, alum, anion and cation retainers, and other additives commonly added to paper, such as microparticle systems, may also be added to the pulp. Can be.

The following examples are intended to illustrate the invention in more detail. Unless otherwise noted, all ratios and fractions in the examples are by weight and all temperatures are in degrees Celsius. When referring to pulp by weight, it is the pulp's original weight, ie the weight of the pulp including the equilibrium moisture content.

Example 1

Degeneration of Northern Softwwod Kraft (NSK) Pulp:

1600 g of a stirred suspension of 3% concentration of NSK pulp (48 g pulp) was charged with 4.8 mg of 4-acetamido-TEMPO and 0.24 g of sodium bromide (0.01% and 0.5% based on pulp weight, respectively). Added. 0.49 N sodium hydroxide was used to adjust the pH of the mixture to 9.5. Sodium hypochlorite (10.11 g; 9.5% solution; 2% owp) with pH adjusted to 9.5 using concentrated HCl was added all at once, and the mixture was stirred at 25 ° C. for 30 minutes. 0.49 N of NaOH (7.9 mL) was added using Brinkmann pH STAT 718 Titrino to keep the pH of the suspension constant at 9.5. In the last step, ascorbic acid was added to the mixture to lower the pH to a range of 4.0 to 4.5 and the reaction was terminated.

The pulp is filtered, washed extensively with water adjusted to pH 4.5-5.5, and then reslurried with water for use in subsequent handsheet preparation, or dried in air at room temperature for other uses. I was.

Determination of Aldehyde Content in Modified Pulp:

The aldehyde content of the modified pulp was determined by titrating with hydroxyamine hydrochloride through oxime derivatization according to the following reaction and method.

The pH of the 3% concentration of the pulp oxide suspension dissolved in 1200 g of water was adjusted to 4 using aqueous HCl solution. Aqueous solution of 2M hydroxyamine hydrochloride (15 mL) adjusted to pH 4 by HCl was added to the resulting mixture. During the reaction, the pH of the mixture was maintained at 4 by titration with 0.49 N NaOH solution using Brinkmann pH STAT 718 Titrino. Titration was continued (1 hour) until the pH decrease of the mixture was no longer detected. The aldehyde content was calculated to be 8.4 mmol / 100 g pulp using the following equation based on the total consumption of NaOH (4.1 mL):

Determination of Carboxylic Acid Content in Modified Pulp:

The content of carboxylic acid formed during the reaction was calculated from the content of NaOH titrant consumed to maintain the reaction pH (6.8 mL of 0.49 N solution). Additional carboxylic acid produced in the pulp was measured directly (6.9 mmol per 100 g of pulp) using the following equation:

Example 2

Degeneration of Hardwood Pulp:

To 1600 g of a stirred suspension of 3% concentration of hardwood pulp (48 g pulp) was added 4.8 mg of 4-acetamido-TEMPO and 0.24 g of sodium bromide. 0.49 N sodium hydroxide was used to adjust the pH of the mixture to 9.5. Sodium hypochlorite (10.11 g; 9.5% solution; 2% owp) with pH adjusted to 9.5 using concentrated HCl was added all at once, and the mixture was stirred at 25 ° C. for 30 minutes. The pH of the suspension was kept constant at 9.5 by adding 0.49 N of NaOH (7.9 mL) using Brinkmann pH STAT 718 Titrino. In the last step, ascorbic acid (1 g) was added to the mixture to lower the pH to a range of 4.0 to 4.5 and the reaction was terminated. The pulp is filtered, washed extensively with water adjusted to pH 4.5-5.5, and then reslurried with water for use in subsequent handsheet preparation, or dried in air at room temperature for other uses. I was.

As measured in Example 1, the content of aldehyde and carboxylic acid in the modified hardwood pulp was 7.7 mmol to 4.3 mmol per 100 g of pulp, respectively.

Example 3

The modified pulp samples (600-650 CSF) described in Examples 1 and 2 were subjected to 18 lb / 3300 ft ³ handsheets at pH 5-6 and 0.3% concentration on M / K Sheet Former according to TAPPI Standard Test Method T 205. Made with. Prior to making the sheet, a wet part additive (0.5-1.0% of steam or aqueous solution) was added to the pulp suspension in the Waring mixer and mixed for 30 seconds. The amount of addition varied between 2.5 and 20 pounds (lb / t) per tonne of pulp. Conditioned handsheets (25 ° C. and 50% RH) were cut into strips (1 ”wide) and tested for initial wet strength and dry tension at break according to TAPPI Standard Test Methods T 456 and 494.

Table 1 lists the effects of various cationic starch types of polyhydroxy additives on the strength properties of paper when used in combination with the aldehyde modified softwood pulp described in Example 1.

<Table 1> Effect of Cationic Starch Type Polyhydroxy Additives on the Strength Properties of Paper Based on Aldehyde Modified NSK Softwood Pulp

Pulp additive Paper characteristics NSK Softwood Cationic starch Addition amount (lb / t) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) Undenatured radish 0 52 2158 2 Undenatured CATO 232 ^* 10 55 2392 2 denaturalization radish 0 632 2675 24 denaturalization CATO 232 ^* 5 815 2758 30 denaturalization CATO 232 ^* 10 866 3097 28 denaturalization CATO 232 ^* 20 899 3114 29 denaturalization 67 WF QUATWaxy ^* 5 789 2787 28 denaturalization 67 WF QUATWaxy ^* 10 881 2895 30 denaturalization 67 WF QUATWaxy ^* 20 925 3084 30 denaturalization REDIBOND 5330A ^* 5 860 2943 29 denaturalization REDIBOND 5330A ^* 10 895 2824 32 denaturalization REDIBOND 5330A ^* 20 899 2989 30

^* 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (QUAT) modified waxy maize starch; Nitrogen Cation = 0.30%

From the results shown in the table above, when the cationic starch type polyhydroxy compound is mixed with aldehyde and carboxylate modified softwood pulp, the wet strength / drying strength as well as the wet strength and dry strength of the handsheet are considerably high. You can see that it is further improved.

Example 4

This example is a cationic starch type polyhydroxy compound (National Starch and Chemical Company) as a wet strength and dry strength additive used in admixture with aldehyde modified softwood pulp prepared in Example 2 according to the general method described in Example 3. Product, CATO 232) (Table 2).

<Table 2> Effect of Cationic Starch Type Polyhydroxy Additives on the Strength Properties of Paper Based on Aldehyde Modified Softwood Pulp

Pulp additive Paper characteristics Softwood Cationic starch Addition amount (lb / t) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) Undenatured radish 0 28 1343 2 Undenatured CATO 232 ^* 10 46 1429 3 denaturalization radish 0 292 1445 20 denaturalization CATO 232 ^* 5 356 1563 23 denaturalization CATO 232 ^* 10 378 1576 24 denaturalization CATO 232 ^* 20 368 1677 22

^* CATO 232: 3- chloro-2-hydroxypropyl trimethyl ammonium chloride modified waxy maize starch; Nitrogen Cation = 0.30%

From the results shown in the table above, when the cationic starch type polyhydroxy compound is mixed with aldehyde and carboxylate modified softwood pulp, the wet strength / drying strength as well as the wet strength and dry strength of the handsheet are significantly increased. You can see that it is further improved.

Example 5

This example is a cationic starch aldehyde as a wet strength and dry strength additive used in admixture with the aldehyde modified softwood and hardwood pulp prepared in Examples 1 and 2 according to the general method described in Example 3. Product, BOND ™ 1000Puls starch).

Table 3 Effect of aldehyde-acting starch additives on the strength properties of paper based on aldehyde-modified pulp

Pulp additive Paper characteristics NSK Softwood Cationic starch Addition amount (lb / t) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) Undenatured radish 0 28 2171 One Undenatured CO-BOND 1000Puls ^* 10 346 2571 13 denaturalization radish 0 669 2558 26 denaturalization CO-BOND 1000Puls ^* 2.5 738 2600 28 denaturalization CO-BOND 1000Puls ^* 5 828 2926 28 denaturalization CO-BOND 1000Puls ^* 10 1009 3246 31 Hardwood Undenatured CO-BOND 1000Puls ^* 5 28 1343 2 Undenatured CO-BOND 1000Puls ^* 10 240 1518 16 denaturalization radish 0 283 1343 21 denaturalization CO-BOND 1000Puls ^* 2.5 351 1462 24 denaturalization CO-BOND 1000Puls ^* 5 401 1597 25 denaturalization CO-BOND 1000Puls ^* 10 463 1698 27

^* 3-chloro-2-hydroxypropyl trimethylammonium chloride and 2-chloro -N- (2,2- dimethoxy-ethyl) -N- methylacetamide modified waxy maize starch; Nitrogen cation = 0.30% and nitrogen acetal = 0.4%

When the cationic starch aldehyde is mixed with aldehyde and carboxylate modified softwood and hardwood pulp from the results shown in the table, the wet strength / drying strength as well as the wet strength / drying strength ratio of the handsheet are further improved. You can see that.

Example 6

This example is a hydroxyl group of other cationic polysaccharide type as a wet strength and dry strength additive used in admixture with the aldehyde modified NSK softwood pulp prepared in Example 1 according to the general method described in Example 3. Containing polymers [chitosan from Sigma Corporation, cationic cellulose (CELQUAT ™ H-100 derived cellulose resin, Polyquaternium-4), and cationic gum from National Starch and Chemical Company, 3-chloro-2-hydroxypropyltrimethyl-ammonium chloride Modified guar gum; nitrogen cation = 0.30%].

TABLE 4 Effect of hydroxy group-containing polymers of cationic polysaccharide type on the strength properties of papermaking based on aldehyde-modified softwood pulp as additive

Pulp additive Paper characteristics NSK Softwood Polysaccharides Addition amount (lb / t) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) Undenatured radish 0 29 2300 One Undenatured Chitosan 10 72 2447 3 Undenatured Cationic guar 10 49 2527 2 Undenatured CELQUAT H-100 RESIN 10 57 2101 3 denaturalization radish 0 608 2373 26 denaturalization Chitosan 5 630 2479 25 denaturalization Chitosan 10 646 2472 26 denaturalization Chitosan guar 5 737 2538 29 denaturalization Chitosan guar 10 662 2691 25 denaturalization CELQUAT H-100 RESIN 5 835 2537 33 denaturalization CELQUAT H-100 RESIN 10 841 2353 36

From the results shown in the table above, it can be seen that when the various polysaccharides are mixed with aldehyde and carboxylate modified pulp, the wet / dry strength as well as the wet / dry strength ratio of the handsheet are significantly further improved. .

Example 7

Poly (MAPTAC-co-DMA-co-HEMA) hydroxy group-containing terpolymer synthesis:

This example shows several types of {poly ([3- (methacryloylamino) propyl] methylammonium chloride (MAPTAC) -co-N, N-dimethylacrylics used with aldehyde-modified pulp as temporary wet strength additives. Amide (DMA) -co-2-hydroxyethyl methacrylate (HEMA)} terpolymer The following methods were used for the synthesis of terpolymer B (Table 5): Different contents using similar methods Polymers A and CK (Table 5) containing monomers of were prepared.

A round bottom flask with four inlets was equipped with a mechanical overhead stirrer, two equal pressure addition funnels, a thermometer, and a nitrogen inlet-mounted reflux condenser. At this time, one of the two addition funnels is attached to an off-set adapter connected to the "Y" shaped adapter, and the other is directly connected to the "Y" shaped adapter. To correct the purity of each component (50% MAPTAC, 99% DMA, 97% HEMA, 97% ammonium persulfate), the weight of the monomers in the beaker was measured (0.63 g anhydrous MAPTAC, 9.42 g Anhydrous DMA, 2.53 g HEMA). The monomer mixture was then diluted with water to a total weight of 125 g. The obtained solution was placed in an addition funnel. An ammonium persulfate solution made by dissolving ammonium persulfate (0.06 g, 0.5 wt%) in 125 g of water in a beaker was placed in a second addition funnel. The top of the two funnels was sealed using a rubber septum and injected with nitrogen gas for 20 minutes. Then, an initial charge consisting of 25 ml of monomer solution and 25 ml of initiator solution was injected into the reaction flask. The starting charge was stirred at 65-70 ° C. for 30 minutes and then the monomer and initiator solution were added dropwise simultaneously over 1.5 hours while maintaining the temperature of 65-70 ° C. using an oil bath. After the addition was completed, the polymerization solution was left at a temperature of 65 to 70 ℃ for 4 to 5 hours. The flask was then cooled to room temperature and the polymer lacquer collected. A small amount of lacquer was cooled for analysis. Polymers were investigated for conversion, concentration, and molecular weight. After the monomer was converted to a polymer, the lyophilized polymer was dissolved in double water (D ₂ O) and analyzed by ¹ H or ¹³ C NMR spectroscopy. The concentration of the polymer lacquer (typically 5.0-5.5%) was determined by measuring the weight difference before and after heating a small sample at 105 ° C. for 1 hour. Specific viscosity (IV) (2.2 dl / g) was measured using 0.1 g / 100 mL of polymer dissolved in 0.1 N potassium chloride at a temperature of 25 ° C.

Table 5 lists their effects as wet strength and dry strength additives used with a series of terpolymer and aldehyde modified softwood pulp with varying compositions of synthesized MAPTAC, DMA, and HEMA.

TABLE 5 Hydroxy Functional Synthetic Copoly Used with Aldehyde Modified Softwood Pulp as Strength Additive in Papermaking

Terpolymer Composition Paper characteristics Sample ^* MAPTAC (g) DMA (g) HEMA (g) IV (dl / g) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) Modified Softwood 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

^* 10 lb / t units

Example 8

This example relates to the use of various synthetic polymers having different aldehyde functional groups as wet strength and dry strength additives used in admixture with the aldehyde modified NSK softwood pulp prepared in Example 1 according to the general method described in Example 3. Table 6 (Cat-PVOH = cationic poly (vinyl alcohol) (manufactured by Kuraray Co. Ltd., polymer CM-318), PAM = poly (acrylamide-co-diallyldimethylammonium chloride) (manufactured by Aldrich), Polymin PR971L = poly (ethyleneimine) from BASF Corporation].

TABLE 6 Effect of various aldehyde-reactive functional group-containing synthetic polymers as additives on the strength properties of paper based on aldehyde-modified softwood pulp

Paper characteristics additive Addition amount (bl / t) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) radish 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 relates to spray application of several hydroxy functional additives to preformed handsheets made of aldehyde modified softwood. Thus, after the hand sheet was prepared according to the method described in Example 3, various synthetic and natural hydroxy functional polymers were evenly spray applied on both sides of the sheet with a 0.5-1% solution using a manual sprayer. The polymer adduct was measured based on the weight increase of the wet sheet and dried in air at room temperature. Then, they were conditioned and tested as described in Example 3. The results are summarized in Table 7 below. [PVOH = poly (vinyl alcohol) (98% hydrolyzed, MV 124,000-186,000, manufactured by Aldrich), Frodex 20 = DE 20 maltodextrin (manufactured by American Maize Corp.), Pullulan (Polysciences Corp.).

Table 7 Effects of hydroxy-functional polymers on spray application and strength properties of handsheets made of aldehyde-modified softwood

Paper characteristics additive Addition amount (bl / t) Wet Tension (g / in) Drying tension (g / in) Wet / Dry Ratio (%) radish 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 Pulluan 12 710 3151 23 Pulluan 20 725 2935 25

The present invention provides a papermaking product having improved wet strength and dry strength properties.

Claims (15)

In the method of manufacturing paper having a wet strength, a temporary wet strength, a dry strength, and a high wet strength / dry strength ratio characteristics, Aldehyde-modified cellulose pulp prepared by oxidizing aldehyde-modified cellulose or cellulose pulp in an aqueous system containing an oxidizing agent having an oxidizing power equivalent to about 5.0 g or less of active chlorine per 100 g of cellulose and an intermediate effective amount of nitroxy radical is converted into a pulp stock solution. Using, A method of making paper, comprising the step of adding an effective amount of at least one additive comprising an aldehyde functional polymer or a polymer containing a functional group capable of reacting with an algialdehyde group. The method of claim 1, A process for producing papermaking, wherein the aldehyde reactive functional group in the additive polymer is selected from the group consisting of hydroxy, amino, amido, thiol, imido, and carboxylic acid groups, or selected from alkali, alkaline earth or ammonium salts thereof. The method according to claim 1 or 2, The manufacturing method of the paper manufacture whose aldehyde-reactive functional group is a hydroxyl group. The method according to any one of 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 ° C. The method according to any one of claims 1 to 4, A process for producing papermaking wherein the cellulose pulp contains about 1-20 mmol of aldehyde per 100 g of cellulose. The method according to any one of claims 1 to 5, Process for preparing paper, wherein the nitrox radical catalyst has the formula: Wherein Y is H, OH, or NH-C (O) -CH ₃ . The method according to any one of claims 1 to 6, The process for producing papermaking, wherein the aldehyde reactive functional group in the additive polymer is selected from the group consisting of hydroxy, amino, amido, thiol, imido, and carboxylic acid groups, or from alkali, alkaline earth or ammonium salts thereof. The method according to any one of claims 1 to 7, A method for producing paper, wherein the aldehyde reactive functional group in the additive polymer is a hydroxy group. The method according to any one of claims 1 to 8, About 0.05 to 15% by weight of additives, based on the dry weight of the pulp. Papermaking produced by the method of any one of claims 1 to 9. In the method of manufacturing paper having a wet strength, temporary wet strength, dry strength, and a high wet strength / dry strength ratio characteristics, A process for producing paper, which uses an aldehyde-modified cellulose pulp as the pulp stock solution and improves the properties of the paper by adding an effective amount of a hydroxy group-containing polymer. The method of claim 11, A process for producing paper, wherein the hydroxyl group-containing polymer is a carbohydrate selected from the group consisting of starch, cellulose and gum. The method according to claim 11 or 12, wherein About 0.05 to 15% by weight of additives, based on the dry weight of the pulp. The method according to any one of claims 11 to 13, A method of producing paper, wherein the carbohydrate is selected from the group consisting of cations, anions, amphoteric ions, esters and ethers. Papermaking produced by the manufacturing method of any one of claims 11-14.