JP3075589B2 - Papermaking method and papermaking additive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for papermaking and an additive for papermaking.
A paper-making method using a combination of a cationic acrylamide polymer obtained by a Hoffman decomposition reaction in a short time and a cationic acrylamide polymer produced by copolymerization, and a cationic acrylamide obtained by such a Hoffman decomposition reaction The present invention relates to a papermaking additive comprising a styrene-based polymer and a cationic acrylamide-based polymer produced by copolymerization.

[0002]

2. Description of the Related Art In recent years, the ratio of waste paper to pulp raw material has tended to increase due to the deterioration of raw material circumstances, and there has been a demand for a paper strength enhancer that exhibits higher paper strength. On the other hand, in terms of operation, there is a demand for a chemical that improves the drainability and a chemical that improves the drainability and a chemical that improves the drying property in view of a request to reduce the unit consumption of steam. The Hoffman decomposition product of polyacrylamide (Hoffman PAM) is a cationic resin having a primary amino group directly bonded to the polymer main chain, and has conventionally been used as a drainage improver or paper strength enhancer in the paper manufacturing process. Have been used. The Hoffman PAM obtained by reacting a hypohalite with an alkaline solution at a high temperature for a short time in an alkaline region has a cationic property that changes with time in an aqueous solution, as in the case of a conventional low-temperature and long-time reaction. manner can avoid the problem of deterioration with time of the disappearance of its excellent present inventors that capitalize the characteristics we found. The feature of Hoffman PAM lies in the strength of cohesion, but not only in improving drainage, but also in improving strength between fibers due to hydrogen bonding of a primary amino group which is also a cationic group.

[0003]

However, Hoffman PA
The present inventors have found that when M is used alone, effective fixation to pulp fibers may not be achieved depending on papermaking conditions, and the characteristics of Hoffman PAM may not be fully exhibited. In such a case, it can be solved in terms of drainage by increasing the amount of Huffman PAM added, but on the other hand, it breaks the formation of the paper, and therefore always gives satisfactory results in terms of paper strength and printing characteristics. I found that I could not do it.

[0004]

Means for Solving the Problems In view of the above points, the present inventors have studied various additives having an effect of being used in combination with Huffman-decomposed PAM, and as a result, have found that a cationic acrylamide-based polymer produced by copolymerization is obtained. It has been found that the drainage can be controlled without lowering the paper strength performance by adding the coalescing together, and the present invention has been achieved.

That is, the present invention relates to a method for preparing an acrylamide polymer and a hypohalite under alkaline conditions from 50 to 50%.
A cationic acrylamide-based polymer (A) obtained by reacting in a short time within a temperature range of 110 ° C .; and (a) a general formula (I)

[0006]

Embedded image (Wherein, R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or N
H and n each represent an integer of from 2 to 4), and / or salts of organic or inorganic acids thereof, or a quaternizing agent obtained by reacting the quaternizing agent with the general formula (I). Quaternary ammonium salts, (b) α, β-unsaturated carboxylic acids and / or their salts, and (c) general formula (II) CH ₂ ＣC (R ₅ ) -CONH ₂ (II) ₅ represents hydrogen or a methyl group) and a cationic polyacrylamide obtained by copolymerizing with an acrylamide-based monomer represented by the formula (1), is added to a pulp slurry, and then a wet pulp sheet is formed. Paper-making method characterized by carrying out a drying treatment with a dryer, and a method in which an acrylamide-based polymer and a hypohalite are subjected to 50 to 1 under alkaline conditions.
A cationic acrylamide-based polymer (A) obtained by reacting in a short time at a temperature range of 10 ° C .; and (a) a general formula (I)

[0007]

Embedded image (Wherein, R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or N
H and n each represent an integer of from 2 to 4), and / or salts of organic or inorganic acids thereof, or a quaternizing agent obtained by reacting the quaternizing agent with the general formula (I). Quaternary ammonium salts, (b) α, β-unsaturated carboxylic acids and / or their salts, and (c) general formula (II) CH ₂ ＣC (R ₅ ) -CONH ₂ (II) ₅ represents hydrogen or a methyl group) and a cationic polyacrylamide obtained by copolymerization with an acrylamide-based monomer represented by the formula (1): Hereinafter, the present invention will be described in detail.

The acrylamide polymer used in the present invention is a homopolymer of acrylamide (or methacrylamide) or a copolymer of at least one unsaturated monomer copolymerizable with acrylamide (or methacrylamide). It refers to a copolymer which is grafted onto a water-soluble polymer such as starch. Examples of the copolymerizable monomer include a hydrophilic monomer, an ionic monomer, and a lipophilic monomer, and one or more of these monomers can be used. Specifically, as a hydrophilic monomer, for example, diacetone acrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-ethylmethacrylamide, N-
Ethyl acrylamide, N, N-diethylacrylamide,
N-propylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N-acryloylmorpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol (meth) acrylates, N
-Vinyl-2-pyrrolidone and the like.

The ionic monomers include, for example, acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid,
Acids such as acrylamide-2-methylpropanesulfonic acid and salts thereof, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate,
Examples include amines such as N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, N, N-dimethylaminopropylacrylamide, and salts thereof.

As the lipophilic monomer, for example, N, N-di-
n-propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide, Nn-hexylmethacrylamide, Nn-octylacrylamide, Nn-octylmethacrylamide, N-tert-
N-alkyl (meth) acrylamide derivatives such as octylacrylamide, N-dodecylacrylamide, Nn-dodecylmethacrylamide, N, N-diglycidylacrylamide, N, N-diglycidylmethacrylamide, N- (4-glycidyl) Xybutyl) acrylamide,
N- (4-glycidoxybutyl) methacrylamide, N
-(5-glycidoxypentyl) acrylamide, N-
N- such as (6-glycidoxyhexyl) acrylamide
(Ω-glycidoxyalkyl) (meth) acrylamide derivative, methyl (meth) acrylate, ethyl (meth)
(Meth) acrylate derivatives such as acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, Olefins such as ethylene, propylene, butene,
Styrene, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like can be mentioned. The amount of the unsaturated monomer used for the copolymerization varies depending on the type of the unsaturated monomer and the combination thereof, and cannot be specified unconditionally, but is generally in the range of 0 to 50% by weight.

As the water-soluble polymer for graft-copolymerizing the above-mentioned monomers, any of a natural polymer and a synthetic polymer can be used. Modified products such as starch and oxidized starch, carboxyl starch, dialdehyde starch, cationized starch and the like derived from various natural sources; cellulose derivatives such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose; alginic acid, agar, pectin, carrageenan, dextran, Pullulan, konjac, gum arabic, casein, gelatin and the like can be mentioned. Examples of the synthetic system include polyvinyl alcohol, polyvinyl ether, polyvinylpyrrolidone, polyethyleneimine, polyethyleneimine, polyethylene glycol, polypropylene glycol, polymaleic acid copolymer, polyacrylic acid, and polyacrylamide. The amount of the monomer added to the water-soluble polymer is in the range of 0.1 to 10.0 times based on the water-soluble polymer.

Next, the above-mentioned monomer is polymerized to produce an acrylamide polymer. Radical polymerization is preferable as the polymerization method, and polar solvents such as water, alcohol, and dimethylformamide can be used as the polymerization solvent. However, since the Hoffman decomposition reaction is performed in an aqueous solution, aqueous polymerization is preferable. The monomer concentration at that time is preferably 2 to 30% by weight,
5 to 30% by weight. The polymerization initiator is not particularly limited as long as it is water-soluble, and is usually used after being dissolved in an aqueous monomer solution. Specifically, in the peroxide system, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl peroxide and the like can be mentioned. In this case, it can be used alone, but can also be used as a redox polymerizer in combination with a reducing agent. As the reducing agent, for example, salts of lower ionization such as sulfite, hydrogen sulfite, iron, copper, and cobalt; organic amines such as N, N, N ', N'-tetramethylethylenediamine; and aldose and ketose And the like.

The azo compound includes 2,2'-azobis-2-amidinopropane hydrochloride, 2,2'-azobis-2,
4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid and salts thereof can be used.
Further, two or more of the above-mentioned polymerization initiators can be used in combination. When graft-polymerizing a water-soluble polymer, a second polymerization initiator other than the above-mentioned polymerization initiator may be used.
Transition metal ions such as cerium ion and ferric ion can be used, and may be used in combination with the above-mentioned polymerization initiator. The amount of the initiator added is 0.01 to 10 with respect to the monomer.
%, Preferably 0.02 to 8% by weight. In the case of a redox system, the amount of the reducing agent to be added is 0.1 to 100%, preferably 0.2 to 80% on a molar basis with respect to the initiator.

The polymerization temperature is about 30 to 90 ° C. in the case of a single polymerization initiator, and is lower, generally about −5 to 50 ° C. in the case of a redox polymerization initiator. Further, it is not necessary to keep the same temperature during the polymerization, and the temperature may be changed as appropriate with the progress of the polymerization. Generally, the temperature is raised by polymerization heat generated as the polymerization proceeds. The atmosphere in the polymerization vessel at that time is not particularly limited, but it is better to replace the atmosphere with an inert gas such as nitrogen gas in order to promptly carry out the polymerization. The polymerization time is not particularly limited.
~ 20 hours. Next, a Hoffman decomposition reaction of the acrylamide-based polymer produced by the above method is performed. At that time, when the production of polyacrylamide as a raw material is carried out with an aqueous solution, the polyacrylamide can be used for the reaction as it is or after dilution as necessary. In the case of a graft copolymer, ungrafted polyacrylamide is also by-produced, but it is usually subjected to the reaction without separation.

The Hoffman decomposition reaction is carried out by allowing a hypohalite to act on an amide group of polyacrylamide in the presence of an alkaline substance. Examples of hypohalous acid include hypochlorous acid, hypobromite, and hypohalous acid. And iodic acid.
Examples of the hypochlorite include metal hypochlorite or alkaline earth metal salts, and specifically, sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, and hypochlorous acid. There are calcium, magnesium hypochlorite, barium hypochlorite and the like. Similarly, hypobromite and hypoiodite include alkali metal or alkaline earth metal salts of hypobromite and hypoiodite. It is also possible to generate a hypohalite by blowing a halogen gas into an alkaline solution. On the other hand, examples of the alkaline substance include an alkali metal hydroxide, an alkaline earth metal hydroxide, and an alkali metal carbonate. Among them, an alkali metal hydroxide is preferable, and sodium hydroxide, potassium hydroxide, and hydroxide are preferable. Lithium and the like. The amount of the above-mentioned substance added to polyacrylamide is 0.05 to 2.0 mol, preferably 0.1 to 1.5 mol, based on the amide group for hypohalous acid, and 0.05 to 4.0 mol, preferably, 0.1 to 1.5 mol for the alkaline substance. 0.1
~ 3.0 mol. The pH at that time is generally in the range of 11-14. The concentration of polyacrylamide at that time was approximately 0.
The content is from 1 to 17.5% by weight, but it is usually preferably from 0.1 to 10% by weight from the viewpoint that stirring becomes difficult and gelation easily occurs when the reaction concentration is high. Also,
If the reaction concentration is less than 1%, there is a problem that the reaction rate becomes slow. Therefore, the concentration is more preferably 1 to 10% by weight.
The reaction temperature is in the range of 50 to 110 ° C, preferably 6
It is in the range of 0-100 ° C.

Next, the Hoffman decomposition reaction is performed within a short time within the above-mentioned temperature range. The reaction time depends on the reaction temperature and the concentration of the polymer in the reaction solution, and cannot be said unconditionally. Is 1% by weight, 50
It is enough within ten and several minutes at 65 ° C, within several minutes at 65 ° C, and within several tens of seconds at 80 ° C. Further, the higher the polymer concentration, the shorter the reaction time. In the above-described concentration range, the relationship between the reaction time and the reaction temperature may be approximately within the range between the following two relational expressions (1) and (2) (Equation 1). If the reaction is carried out, suitable results can be obtained.

[0017]

T (sec) ≧ exp (15,150 / (273 + T)) × 2.5 × 10 ⁻²⁰ (1) t (sec) ≦ exp (15,150 / (273 + T)) × 10 ⁻¹⁸ +30 (2) T: reaction temperature (° C.) 50 ≦ T ≦ 110

The cationic acrylamide polymer (A) (hereinafter referred to as Hoffman-decomposed PAM) produced under the above conditions
The cation equivalent measured by colloid titration at pH 2 is generally in the range of 0 to 10.0 meq / g.
The cation equivalent can be controlled by the amount of hypohalite added. Further, since the reaction is carried out in an alkaline region, the amide group is hydrolyzed and a carboxyl group is by-produced. The amount of by-product is represented by an anion equivalent measured by colloid titration at pH 10, and is generally in a range of 0 to 10.0 meq / g. The amount of the by-product can be controlled by the amount of the added alkaline substance.

Next, after carrying out the reaction under the above conditions, it is preferable to stop the reaction in order to suppress the progress of the side reaction. However, when the paper is used for papermaking immediately after the reaction, it may not be necessary to stop the reaction. As a method for terminating the reaction, methods such as (1) adding a reducing agent, (2) cooling, and (3) lowering the pH of the solution by adding an acid can be used alone or in combination.
(1) is a method of inactivating remaining hypohalite and the like by reaction with a reducing agent. Generally, at the end of the Hoffman decomposition reaction, a compound having active chlorine such as unreacted hypohalite remains. If such a reaction solution is used as a paper strengthening agent, it may cause rust in a paper machine. Therefore, a reducing agent is usually used to inactivate active chlorine. However, the hypohalite reacts at an equimolar or less relative to the acrylamide unit mole number of the polymer, and when the reaction is performed at a high temperature, almost no unreacted hypohalite remains at the end of the reaction. The present inventors have found that. Therefore, it can be used as a paper strength agent without deactivating active chlorine by using a reducing agent. The method (2) is a method of suppressing the progress of the reaction by cooling. Examples of the method include a method of cooling using a heat exchanger and a method of diluting with cold water. The temperature at that time is usually 50
C. or lower, preferably 45.degree. C. or lower, more preferably 40.degree. C. or lower. In (3), the Huffman decomposition reaction is stopped by lowering the pH of the solution at the end of the reaction, which usually shows an alkalinity of pH 12 to 13, using an acid, and at the same time, the progress of the hydrolysis reaction is suppressed. The pH at that time may be neutral or lower, and is preferably in the range of pH 4 to 6. The reaction termination method can be appropriately selected from (1) to (3) depending on the reaction conditions, and these methods may be combined.

In the present invention, the cationic monomer represented by () is a (meth) acrylate derivative represented by dimethylaminoethyl (meth) acrylate or diethylaminoethyl (meth) acrylate, and dimethylaminopropyl (meth) acrylate. Acrylamide or a (meth) acrylamide derivative substituted with diethylaminopropyl (meth) acrylamide is exemplified. The salt of an organic or inorganic acid means a salt of an inorganic acid such as sulfuric acid, hydrochloric acid or phosphoric acid, or a salt of an organic acid such as acetic acid or formic acid. The quaternary ammonium salts obtained by reacting the general formula (I) with a quaternizing agent include a vinyl monomer having a tertiary amino group and methyl chloride, methyl bromide, methyl iodide, dimethyl A vinyl monomer having a quaternary ammonium salt obtained by a reaction with a quaternizing agent such as sulfuric acid, epichlorohydrin or benzyl chloride can be exemplified. In the present invention, a tertiary amino group-containing vinyl monomer or a salt of an organic or inorganic acid thereof may be used in combination with a quaternary ammonium salt obtained by reaction with a quaternizing agent. Absent. The mixing ratio of these is not particularly limited. The amount of these cationic monomers is usually 0.5 to 70.
mol%, preferably 2 to 50 mol%.

The α, β-unsaturated carboxylic acids or salts thereof such as alkali metal salts or ammonium salts of the present invention are vinyl monomers having an anionic property, such as maleic acid, fumaric acid, itaconic acid, ) Unsaturated carboxylic acids such as acrylic acid, crotonic acid or citraconic acid, or alkali metal salts such as sodium or potassium salts or ammonium salts thereof. The amount of these monomers used is 0.5 to 20 mol%, preferably 2 to 20 mol%.
20 mol%. The acrylamide-based monomer represented by the general formula (II) of the present invention includes acrylamide and methacrylamide, and it is sufficient that the monomer is commercially available in the form of a powder or an aqueous solution and is used industrially.
The amount of these monomers used is 10 to 90 mol%.

In the present invention, a crosslinkable monomer can be used as the fourth component in addition to (a) to (c). Examples of the crosslinkable monomer include a monomer having at least two or more double bonds in a molecule and an N-alkoxymethyl (meth) acrylamide derivative. Specific examples of the former include methylenebisacrylamide, diallylacrylamide, triacrylformal, diacryloylimide, ethylene glycol acrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 4-butylene glycol dimethacrylate, glycerol dimethacrylate neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, divinylbenzene, diallyl phthalate and the like can be used.

The latter N-alkoxymethyl (meth) acrylamide derivatives include N-hydroxymethyl (meth) acrylamide, for example, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (Meth) acrylamide, Nn-butoxymethyl (meth) acrylamide,
N-tert.-butoxymethyl (meth) acrylamide and the like can be used. The amount of the cross-linking agent used depends on the type of the cross-linkable monomer and cannot be described unconditionally, but is usually 0.0001 to
20 mol%, preferably 0.001 to 10 mol%. If it is less than 0.0001 mol%, there is a disadvantage that the paper strength effect cannot be sufficiently exhibited, and if it exceeds 20 mol%, there is a disadvantage that gelation occurs.

As a method for obtaining the cationic polyacrylamide (B) obtained by polymerizing (a) and (b) of the present invention, a generally known method used for the polymerization of this kind of water-soluble vinyl monomer is used. Is used. For example, radical polymerization is preferable as the polymerization method. The monomer concentration is 2 to 30% by weight, preferably 5 to 30% by weight. The polymerization initiator is not particularly limited as long as it is water-soluble, and is usually used after being dissolved in an aqueous monomer solution. Specifically, peroxides such as hydrogen peroxide and benzoyl peroxide, persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, bromates such as sodium bromate and potassium bromate, and perboric acid Sodium, potassium perborate, perborate such as ammonium perborate, sodium percarbonate, potassium percarbonate, percarbonate such as ammonium percarbonate, sodium perphosphate, potassium perphosphate, ammonium perphosphate And tert.-butyl peroxide. In this case, it can be used alone, but can also be used as a redox polymerizer in combination with a reducing agent. As the reducing agent, for example, salts of lower ionization such as sulfite, hydrogen sulfite, iron, copper, and cobalt; organic amines such as N, N, N ', N'-tetramethylethylenediamine; and aldose and ketose And the like.

The azo compounds include 2,2'-azobis-4-amidinopropane hydrochloride and 2,2'-azobis-2,4-
Dimethyl valeronitrile, 4,4'-azobis-4-cyanovaleic acid and salts thereof can be used. Furthermore,
Two or more of the above-mentioned polymerization initiators can be used in combination. The polymerization temperature is lower, generally about 30 to 90 ° C. for a single polymerization initiator, and lower, generally about 5 to 50 ° C. for a redox-based polymerization initiator. Further, it is not necessary to keep the same temperature during the polymerization, and the temperature may be changed as appropriate with the progress of the polymerization. Generally, the temperature is raised by polymerization heat generated as the polymerization proceeds. The atmosphere in the polymerization vessel at that time is not particularly limited, but it is better to replace the atmosphere with an inert gas such as nitrogen gas in order to promptly carry out the polymerization. The polymerization time is not particularly limited.
~ 20 hours. The method of the present invention is used in the step of papermaking pulp, and has a great effect on improving drainage for improving drainage during papermaking and enhancing paper strength for enhancing mechanical strength of paper.

In the present invention, Huffman-decomposed PAM (A)
(Hereinafter simply referred to as Hoffman-decomposed PAM) and cationic polyacrylamide (B) may be used in any proportion depending on the pulp raw material and white water.
5: 5: 95, preferably 80:20 to 20: 8
0. The method of adding the cationic polyacrylamide is to add the Huffman-decomposed PAM and the cationic polyacrylamide (B) individually to the pulp slurry, or to mix the Hoffman-decomposed PAM and the cationic polyacrylamide (B) and then mix the pulp slurry. And any of these methods may be used.

In the case of the combination of Hoffman-decomposed PAM and cationic polyacrylamide (B), the effect may be further increased when a sulfate band or a water-soluble anionic resin is used in combination. The water-soluble anionic resin used at this time is
It is a water-soluble resin containing an anionic substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group or a salt thereof, for example, an anionic acrylamide resin, an anionic polyvinyl alcohol resin, carboxymethyl cellulose, carboxymethyl Modified starch, sodium alginate and the like. There is no particular limitation on the location where the Huffman-decomposed PAM and the cationic polyacrylamide (B) are added to the pulp slurry before or after the addition thereof, or simultaneously. It is also possible to mix each of the Huffman-decomposed PAM and the cationic polyacrylamide (B), or to mix the Huffman-decomposed PAM and the cationic polyacrylamide (B).

The addition site may be any location before the wet sheet is formed, and it is better to add the agent at a location near the papermaking wire section where the chemical is sufficiently diluted and mixed with the pulp slurry. It is selected from mixing box, seed box, white water pit, screen outlet, etc. As a paper machine used for papermaking, any of a fourdrinier paper machine and a circular net paper machine may be used. The concentration of the papermaking additive is 0.5 to
After addition to the pulp slurry at 5.0%, pH 4.0-9.0, temperature 20-70 ° C, a wet sheet is formed in the wire part and then water pressed in the press part. Nip pressure in the press part is in the range of 20~400kg / cm ^2. The wet paper web that has passed through the press part moves to the dry part and is dried by steam. At this time, the vapor pressure is 2-15kg / c
m ² and dried by a drum at 80-200 ° C. Thereafter, it is possible to perform processing with a chemical for the purpose of improving printability, improving surface strength, and improving water resistance and water repellency in a size press or calendar.

The papermaking additive in the present invention is a water-soluble mixture containing Huffman-decomposed PAM and cationic polyacrylamide (B) as active ingredients.
It is in the range of 0.001-50%. The mixing ratio of the cationic polyacrylamide (B) to the Hoffman-decomposed PAM is 95: 5 to 5:95, preferably 80:20 to 2 by weight.
0:80. If the mixing ratio is too small, the mixing effect is not exhibited, while if too large, the properties of the Huffman-decomposed PAM are impaired. The Hoffman decomposition rate at this time is not particularly limited, but is generally 5 to 60 mol%, preferably 10 to 5 mol%.
0 mol%. As a method for mixing the Hoffman-decomposed PAM with the cationic polyacrylamide (B), the solution after the Hoffman-decomposition reaction is usually in a pH range of 12 to 13, but before mixing with the cationic polyacrylamide (B), an inorganic acid or The pH can be lowered with an organic acid, and after mixing with cationic polyacrylamide (B), p
It is also possible to lower H, and the papermaking additive in the present invention is in the range of pH 2 to 14.

By manufacturing according to the method described above,
It is possible to improve drainage without lowering the paper strength, specifically, the burst strength, the Z-axis strength, the compressive strength, and the like. Therefore, when the method of the present invention is applied, when used for a material such as corrugated cardboard or newsprint in which waste paper occupies a high proportion, the effect is very large, and paper with high paper strength can be produced. Further, the present invention is not limited to corrugated cardboard and newsprint, and paper in which strength is required, and in the case where drainage is required in the papermaking process, a paper having excellent paper strength with excellent productivity can be produced. Will be possible.

[0031]

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not necessarily limited to the following examples. All percentages are by weight unless otherwise specified.

Production Example 1 675 g (94 mol%) of 40% acrylamide was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube.
, Dimethylaminoethyl methacrylate 23.1 g (4 mol
%), 5.8 g (2 mol%) of acrylic acid, 62.3 mg (0.01 mol%) of bismethylene acrylamide and 1,004 g of water, and then adjusted to pH 4.5 with a 10% aqueous sulfuric acid solution.
Thereafter, the internal temperature was raised to 40 ° C. while blowing nitrogen gas. While stirring, a 10% aqueous solution of ammonium persulfate and a 10% aqueous solution of sodium bisulfite were added to initiate polymerization. Thereafter, the temperature was maintained at 85 ° C., and water was added 3 hours after the start of the polymerization to complete the polymerization reaction.
15.3%, Brookfield viscosity at 25 ° C 6,800cp
A stable aqueous solution of cationic polyacrylamide having a pH of 4.3 was obtained. Production Example 2 30.0 g of a 10.0 wt% aqueous solution of polyacrylamide (Brookfield viscosity at 25 ° C .: 3,400 cp) was placed in a 500 ml beaker, diluted with 30.0 g of distilled water, and heated to 80 ° C. with stirring. A mixed solution of sodium chlorite and NaOH (sodium hypochlorite concentration: 1.0 mol / kg, NaOH
After 15 seconds, 225.7 g of cold water at 5 ° C. was added to stop the reaction to obtain a 1 wt% acrylamide polymer (Hoffman PAM (A)). A part of the reaction product was taken in an aqueous solution of pH 2 and subjected to colloid titration with a 1/400 N-potassium polyvinylpolysulfonate aqueous solution using toluidine blue as an indicator. The cation value was 3.8 meq./g. In the following tests, Hoffman PAM (A) was used immediately after production.

Example 1 A commercially available rosin emulsion sizing agent was added to a pulp slurry having a beating degree (Canadian Standard Freeness; hereinafter, referred to as CSF) of 400% and a pulp slurry having a concentration of 1.0%. % And stirred for 2 minutes. Subsequently, 1.0% of aluminum sulfate was added on a dry weight basis, and the mixture was further stirred for 1 minute. At this time, the pH of the pulp slurry was 5.1. Next, 0.30% of the cationic polyacrylamide obtained in Production Example 1 was added on a dry weight basis, and after stirring for 1 minute, 0.10% of the Hoffmann-decomposed PAM (A) obtained in Production Example 2 was added on a dry weight basis. After continuing stirring for another 1 minute, take a part of the pulp slurry, and use CSF according to JIS-P-8121.
Was measured, and the rest was made with a TAPPI square sheet machine. Subsequently, it was dried for 2 hours with a blow dryer at 110 ° C. to obtain a handmade paper having a basis weight of 125 ± 3 g / m ² . This handmade paper
Measure "specific compressive strength" according to JIS-P-8126, "specific burst strength" according to JIS-P-8112 and "Z-axis strength" using an internal bond tester manufactured by Kumagaya Riki Kogyo did. The results are shown in Table 1.

[0034]

[Table 1]

Example 2 The cationic polyacrylamide obtained in Production Example 1 was added at 0.20% on a dry weight basis, and the Hoffman-decomposed PAM (A) obtained in Production Example 2 was added at 0.20% on a dry weight basis. A hand-drawing test was performed in the same manner as in Example 1 except that the test was conducted. The results are shown in Table 1.

Example 3 Except that the cationic polyacrylamide obtained in Production Example 1 was added in an amount of 0.10% on a dry weight basis, and the Hoffman-decomposed PAM (A) obtained in Production Example 2 was added in an amount of 0.30% on a dry weight basis. A hand-drawing test was performed in the same manner as in Example 8. The results are shown in Table 1.

Comparative Example 1 The cationic polyacrylamide obtained in Production Example 1 was used in an amount of 0.1%.
Huffman-decomposed PAM obtained in Production Example 2 by adding 40%
The same test as in Example 1 was performed except that (A) was not added. The results are shown in Table 1. Comparative Example 2 The Huffman-decomposed PAM (A) obtained in Production Example 2 was 0.40%
The same test as in Example 1 was performed except that the cationic polyacrylamide obtained in Production Example 1 was not added. The results are shown in Table 1.

[0038]

As shown in Table 1, the paper made by the method of the present invention surprisingly shows that the Hoffman-decomposed PAM obtained in Preparation Example 2 has a high drainage ability when used alone. While maintaining the level, without being affected by the deterioration of the formation as expected from the drainage, the specific rupture strength as compared with the case where the acrylamide-based polymer obtained in Production Example 1 or 2 is used alone, Excellent in paper strength performance such as specific compression strength and Z-axis strength. Therefore, when the present invention is applied to the case of producing paper having excellent strength while maintaining the drainage at a high level, a great effect is brought about.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-49839 (JP, A) JP-A-58-60094 (JP, A) JP-A-61-200103 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) D21H 17/00-27/42

Claims (2)

(57) [Claims] 1. A cationic acrylamide-based polymer (A) obtained by reacting an acrylamide-based polymer and a hypohalite under alkaline conditions in a temperature range of 50 to 110 ° C. for a short time; a) General formula (I) (Wherein, R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or N
H and n each represent an integer of from 2 to 4), and / or salts of organic or inorganic acids thereof, or a quaternizing agent obtained by reacting the quaternizing agent with the general formula (I). Quaternary ammonium salts, (b) α, β-unsaturated carboxylic acids and / or their salts, and (c) general formula (II) CH ₂ ＣC (R ₅ ) -CONH ₂ (II) ₅ represents hydrogen or a methyl group) and a cationic polyacrylamide obtained by copolymerizing with an acrylamide-based monomer represented by the formula (1), is added to a pulp slurry, and then a wet pulp sheet is formed. And drying by a dryer. 2. A cationic acrylamide-based polymer (A) obtained by reacting an acrylamide-based polymer and a hypohalite in a temperature range of 50 to 110 ° C. for a short time under alkaline conditions; a) General formula (I) (Wherein, R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or N
H and n each represent an integer of from 2 to 4), and / or salts of organic or inorganic acids thereof, or a quaternizing agent obtained by reacting the quaternizing agent with the general formula (I). Quaternary ammonium salts, (b) α, β-unsaturated carboxylic acids and / or their salts, and (c) general formula (II) CH ₂ ＣC (R ₅ ) -CONH ₂ (II) ₅ represents hydrogen or a methyl group) and a cationic polyacrylamide obtained by copolymerizing with an acrylamide-based monomer represented by the following formula: