JPH04370295A - Papermaking method and additive therefor - Google Patents

Abstract

PURPOSE:To obtain paper of excellent paper strength performance while maintaining water filterability at high level by incorporating a pulp slurry with a combination of each specific cationic modified acrylamide-based polymer and cationic acrylamide-based copolymer followed by forming a wet pulp sheet which is then dehydrated and dried. CONSTITUTION:A pulp slurry is incorporated with a combination of (A) a cationic modified acrylamide-based polymer prepared by reaction at 50-110 deg.C under alkaline conditions between an acrylamide-based polymer and a hypohalogenous acid salt and (B) a cationic acrylamide-based copolymer prepared by copolymerization between (1) a cationic monomer of formula I (R<1> is H or methyl; R<2> and R<3> are each H or 1-6C alkyl; X is O or NH; n is 2-4) or a quaternary ammonium salt formed by reaction between the compound of the formula I and a quaternarizing agent, (2) an alpha,beta-unsaturated carboxylic acid and (3) an acrylamide-based monomer of formula II (R<5> is H or methyl), followed by forming a wet sheet, which is then dehydrated with a press and dried, thus obtaining the objective paper. It is preferable that the weight ratio A/B be (80:20)-(20:80).

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a paper making method and an additive for paper making, and more specifically relates to a paper making method and an additive for paper making.
A method for making paper using a combination of a cationic acrylamide polymer obtained by a Hofmann decomposition reaction in a short time and a cationic acrylamide polymer produced by copolymerization, and a cationic acrylamide obtained by such a Hofmann decomposition reaction. The present invention relates to a papermaking additive comprising a cationic acrylamide-based polymer and a cationic acrylamide-based polymer produced by copolymerization.

0002

BACKGROUND OF THE INVENTION In recent years, due to the deterioration of the raw material situation, the proportion of waste paper in pulp raw materials has tended to increase, and there is a need for paper strength enhancers that exhibit higher paper strength. On the other hand, in terms of operation, there is a demand for agents that improve drying properties due to demands for pulp dewatering speed, and agents that further improve freeness, or for reductions in the unit consumption of steam. Hoffmann decomposition reaction product of polyacrylamide (Hoffmann PAM) is a cationic resin having a primary amino group directly bonded to the polymer main chain, and has traditionally been used as a drainage improver and paper strength enhancer in the paper manufacturing process. has been used. Therefore, Hofmann PAM obtained by reacting with a hypohalite in an alkaline region at high temperature for a short period of time has a tendency to change its cationic nature in an aqueous solution over time, unlike the conventional reaction at low temperature for a long time. The present inventors have discovered that it is possible to overcome the problem of deterioration over time, which is the problem of deterioration over time, and to take advantage of its excellent characteristics. Hoffmann PAM is characterized by its strong cohesive force, which not only improves freeness but also improves the strength between fibers through hydrogen bonding between primary amino groups, which are also cationic groups.

0003

[Problem to be solved by the invention] However, Hoffman PA
The present inventors have discovered that when M is used alone, effective fixation to pulp fibers may not be achieved depending on the papermaking conditions, and the characteristics of Hoffmann PAM may not be fully exhibited. In such cases, increasing the amount of Hofmann PAM added can solve the problem in terms of freeness, but on the other hand, it disrupts the texture of the paper, so results are not always satisfactory in terms of paper strength and printing characteristics. I found out that it is not possible.

0004

[Means for Solving the Problems] In view of the above-mentioned points, the present inventors have investigated various additives that have the effect of being added in combination with Hoffmann-decomposed PAM. It has been discovered that freeness can be controlled without deteriorating paper strength performance by adding a coalescent together, leading to the present invention.

[0005] That is, in the present invention, an acrylamide polymer and a hypohalite are mixed under alkaline conditions to
A cationic acrylamide polymer obtained by a short reaction in a temperature range of 110°C (A) and; (a)
General formula (I) (Chemical formula 3)

[0006]

[Formula 3] (wherein, R1 is hydrogen or a methyl group, R2, R3
is a cationic monomer represented by hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or NH, and n is an integer of 2 to 4), and/or their organic or inorganic acid salts, or Quaternary ammonium salts obtained by the reaction of (I) with a quaternizing agent, (b) α,
β-unsaturated carboxylic acid and or salts thereof, (
c) General formula (II) CH2=C(R5)-CONH2
After adding cationic polyacrylamide obtained by copolymerizing with an acrylamide monomer represented by (II) (wherein R5 represents hydrogen or a methyl group) to the pulp slurry, a wet pulp sheet is formed. A method for making paper, which is characterized by dehydrating with a press and drying with a dryer, and an acrylamide polymer and a hypohalite are mixed under alkaline conditions to a concentration of 50 to 11
Cationic acrylamide polymer (A) obtained by reaction in a short time in a temperature range of 0°C; (a) General formula (I) (Chemical formula 4)

[0007]

[Formula 4] (wherein, R1 is hydrogen or a methyl group, R2, R3
is a cationic monomer represented by hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or NH, and n is an integer of 2 to 4), and/or their organic or inorganic acid salts, or Quaternary ammonium salts obtained by the reaction of (I) with a quaternizing agent, (b) α,
β-unsaturated carboxylic acid and or salts thereof, (
c) General formula (II) CH2=C(R5)-CONH2
(II) A papermaking additive comprising a cationic polyacrylamide obtained by copolymerizing with an acrylamide monomer represented by (II) (wherein R5 represents hydrogen or a methyl group) . The present invention will be explained in detail below.

The acrylamide-based polymer used in the present invention is a homopolymer of acrylamide (or methacrylamide), or a copolymer of acrylamide (or methacrylamide) with one or more unsaturated monomers copolymerizable with it. It refers to a copolymer or a graft copolymer to a water-soluble polymer such as starch. Examples of copolymerizable monomers include hydrophilic monomers, ionic monomers, and lipophilic monomers, 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-ethylacrylamide, N,N-diethylacrylamide, N-propylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N-
Examples include acryloylmorpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol (meth)acrylates, and N-vinyl-2-pyrrolidone.

Examples of the ionic monomer include acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, and 2-phenylpropanesulfonic acid.
Acids such as acrylamide-2-methylpropanesulfonic acid and their salts, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylahanoethyl acrylate, N,N-dimethylaminopropyl Examples include amines such as methacrylamide and N,N-dimethylaminopropylacrylamide, and salts thereof.

[0010] Examples of lipophilic monomers include N, N-
Di-n-propylacrylamide, N-n-butylacrylamide, N-n-hexylacrylamide, N-n
-hexyl methacrylamide, N-n-octylacrylamide, N-n-octyl methacrylamide, N-t
N- such as ert-octylacrylamide, N-dodecyl acrylamide, N-n-dodecyl methacrylamide, etc.
Alkyl (meth)acrylamide derivative, N,N-diglycidyl acrylamide, N,N-diglycidylmethacrylamide, N-(4-glycidoxybutyl)acrylamide, N-(4-glycidoxybutyl)methacrylamide, N -(5-glycidoxypentyl)acrylamide, N-(ω-glycidoxyalkyl)(meth)acrylamide derivatives such as N-(6-glycidoxyhexyl)acrylamide, methyl(meth)acrylate, ethyl(meth) Acrylate, (meth)acrylate derivatives such as butyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, Examples include olefins such as ethylene, propylene, and butene, styrene, divinylbenzene, α-methylstyrene, butadiene, and isoprene. The amount of the unsaturated monomer used in the copolymerization varies depending on the type of unsaturated monomers and the combination thereof, and cannot be determined unconditionally, but is generally in the range of 0 to 50% by weight.

Furthermore, both natural and synthetic water-soluble polymers can be used to graft-copolymerize the above-mentioned monomers. Various naturally derived starches and modified products such as oxidized starch, carboxyl starch, dialdehyde starch, and cationized starch; Cellulose derivatives such as methylcellulose, ethylcellulose, carboxymethylcellulose, and hydroxyethylcellulose;
Examples include alginic acid, agar, pectin, carrageenan, dextran, pullulan, konjac, gum arabic, casein, and gelatin. Examples of synthetic systems include polyvinyl alcohol, polyvinyl ether, polyvinylpyrrolidone, polyethyleneimine, polyethyleneimine, polyethylene glycol, polypropylene glycol, polymaleic acid copolymer, polyacrylic acid, polyacrylamide, and the like. The amount of the above-mentioned monomer added to the above-mentioned water-soluble polymer is 0.1 to 10.0 on the basis of the water-soluble polymer.
This is twice the range.

Next, the above monomers are 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, but aqueous solution polymerization is preferable because the Hofmann decomposition reaction is carried out in an aqueous solution. The monomer concentration at that time 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 it is usually used after being dissolved in an aqueous monomer solution. Specifically, peroxide systems include ammonium persulfate, potassium persulfate, hydrogen peroxide, t
Examples include ert-butyl peroxide. In this case, it can be used alone, but it can also be used as a redox polymerization agent in combination with a reducing agent. Examples of reducing agents include sulfites, hydrogen sulfites, salts of lower ionization such as iron, copper, and cobalt, organic amines such as N,N,N',N'-tetramethylethylenediamine, and aldoses and ketoses. Examples include reducing sugars such as

[0013] Examples of azo compounds include 2,2'-azobis-2-amidinopropane hydrochloride, 2,2'-azobis-2,4-dimethylvaleronitrile, and 4,4'-azobis-4-cyanovaleric acid. and its salts, etc. can be used. Furthermore, it is also possible to use two or more of the above-mentioned polymerization initiators in combination. In addition, when graft polymerizing to a water-soluble polymer, in addition to the above-mentioned polymerization initiator, a second polymer may be used as the polymerization initiator.
It is also possible to use transition metal ions such as cerium ions and ferric ions, and they may be used in combination with the above-mentioned polymerization initiators. The amount of initiator added is 0.01 per monomer.
-10% by weight, preferably 0.02-8% by weight. In the case of a redox system, the amount of reducing agent added to the initiator is 0.1 to 100%, preferably 0.2 to 80%, on a molar basis.

[0014] The polymerization temperature is approximately 30 to 90°C in the case of a single polymerization initiator, and lower, approximately -5 to 50°C in the case of a redox polymerization initiator. Further, it is not necessary to maintain the same temperature during the polymerization, and it may be changed as appropriate as the polymerization progresses, and the temperature is generally raised by the polymerization heat generated as the polymerization progresses. The atmosphere inside the polymerization vessel at that time is not particularly limited, but
In order to speed up the polymerization, it is better to substitute with an inert gas such as nitrogen gas. The polymerization time is not particularly limited, but is approximately 1 to 20 hours. Next, the acrylamide polymer produced by the method described above is subjected to a Hoffman decomposition reaction. At this time, when the polyacrylamide used as a raw material is produced in an aqueous solution, it can be used for the reaction as it is or diluted if necessary. In addition, in the case of a graft copolymer, ungrafted polyacrylamide is also produced as a by-product, but it is usually not separated and subjected to the reaction as it is.

[0015] The Hofmann decomposition reaction is carried out by allowing a hypohalite to act on the amide group of polyacrylamide in the presence of an alkaline substance, and examples of hypohalous acid include hypochlorous acid, hypobromous acid, and Examples include iodic acid. Examples of hypochlorites include metal or alkaline earth metal salts of hypochlorous acid, specifically sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, and hypochlorous acid. These include calcium, magnesium hypochlorite, barium hypochlorite, etc. Similarly, hypobromite and hypoiodite include alkali metal or alkaline earth metal salts of hypobromite and hypoiodite. It is also possible to generate hypohalite by blowing halogen gas into the alkaline solution. On the other hand, examples of alkaline substances include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, etc. Among them, alkali metal hydroxides are preferred, and sodium hydroxide, potassium hydroxide, hydroxide Examples include lithium. The amount of the above-mentioned substance added to polyacrylamide is 0.05 to 2.0% based on the amide group of hypohalous acid.
0 mol, preferably 0.1 to 1.5 mol, and in alkaline substances 0.05 to 4.0 mol to the amide group.
mol, preferably 0.1 to 3.0 mol. The pH at that time is generally in the range of 11-14. The concentration of polyacrylamide at that time is approximately 0.1 to 17.5% by weight.
However, as the reaction concentration becomes high, stirring becomes difficult and gelation tends to occur, so it is usually 0.1 to 1.
A range of 0% by weight is preferred. Further, if the reaction concentration is less than 1%, there are problems such as a slow reaction rate, so it 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 to 100°C.

Next, the Hofmann decomposition reaction is carried out within the above-mentioned temperature range in a short time, but the reaction time cannot be generalized because it depends on the reaction temperature and the polymer concentration in the reaction solution. is 1% by weight, 50
At 80°C, within ten minutes is sufficient, at 65°C, within several minutes, and at 80°C, within several tens of seconds. Furthermore, higher polymer concentrations require shorter reaction times. In the above concentration range, the relationship between reaction time and reaction temperature should be approximately within the range between the following two relational expressions (1) and (2) (Equation 1), and the concentration should be considered within that range. A suitable result can be obtained by carrying out the reaction.

[0017]

[Equation 1] t (sec) ≧ exp (15,150/(27
3+T))×2.5×10-20
(1) t(sec) ≦ exp(15,1
50/(273+T))×10-18 +30
(2) T: Reaction temperature (°C) 50 ≦ T ≦ 110

Cationic acrylamide polymer (A) produced under the above conditions (hereinafter referred to as Hoffmann degradation PA)
M(A)) has a cation equivalent of approximately 0 to 10.0 meq/g measured by colloid titration at pH 2.
The cation equivalent can be controlled by adjusting the amount of hypohalite added. Furthermore, since the reaction is carried out in an alkaline region, amide groups are hydrolyzed and carboxyl groups are produced as by-products. The amount of the by-product is indicated by the anion equivalent measured by colloid titration at pH 10, and is generally in the range of 0 to 10.0 meq/g. The amount of by-product can be controlled by the amount of alkaline substance added.

Next, after carrying out the reaction under the above-mentioned conditions, it is preferable to stop the reaction in order to suppress the progress of side reactions. However, if the product is used for paper making immediately after the reaction, it may not be necessary to stop the reaction. As a method for stopping 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 in which remaining hypohalite and the like are deactivated by reaction with a reducing agent. Generally, when the Hofmann decomposition reaction is completed, unreacted compounds containing active chlorine such as hypohalite salts remain. If such a reaction solution is used as a paper strength agent, it may cause rust in the paper machine, so normally a reducing agent is used to deactivate the active chlorine. However, hypohalite reacts in a molar amount less than the number of moles of acrylamide units in the polymer.
The present inventors have also found that when the reaction is carried out at a high temperature, almost no unreacted hypohalite remains at the end of the reaction. Therefore, it is also possible to use active chlorine as a paper strength agent without deactivating it using a reducing agent. (2) is a method of suppressing the reaction progress by cooling, which includes methods such as cooling using a heat exchanger and diluting with cold water. The temperature at that time is usually 50°C or lower, preferably 45°C or lower, and more preferably 40°C or lower. In (3), the pH of the solution at the end of the reaction, which is usually alkaline at pH 12 to 13, is lowered using an acid to stop the Hofmann decomposition reaction and at the same time suppress the progress of the hydrolysis reaction. The pH at that time should just be neutral or lower, preferably in the range of pH 4 to 6. The reaction termination method can be appropriately selected from among (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)acrylic acid ester derivative represented by dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and
Examples include dimethylaminopropyl (meth)acrylamide or (meth)acrylamide derivatives substituted with diethylaminopropyl (meth)acrylamide. Salts of organic or inorganic acids mean salts of inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, or salts of organic acids such as acetic acid and formic acid. The quaternary ammonium salts obtained by the reaction of general formula (I) with a quaternizing agent include the vinyl monomer having the tertiary amino group and methyl chloride, methyl bromide, methyl iodide, dimethyl Examples include vinyl monomers having quaternary ammonium salts obtained by reaction with quaternizing agents such as sulfuric acid, epichlorohydrin, or benzyl chloride. In the present invention, vinyl monomers having a tertiary amino group or their organic or inorganic acid salts may be mixed with quaternary ammonium salts obtained by reaction with a quaternizing agent. do not have. The mixing ratio of these is not particularly limited. The amount of these cationic monomers is usually 0.5 to 70 mo
1%, preferably 2 to 50 mol%.

The α,β-unsaturated carboxylic acids or their salts such as alkali metal salts or ammonium salts of the present invention are anionic vinyl monomers, such as maleic acid, fumaric acid, itaconic acid, (meth) ) Examples include unsaturated carboxylic acids such as acrylic acid, crotonic acid, and citraconic acid, and alkali metal salts or ammonium salts thereof such as sodium salts or potassium salts. The amount of these monomers used is 0.5 to 20 mol%, preferably 2 to 2 mol%.
It is 0 mol%. Acrylamide monomers represented by the general formula (II) of the present invention include acrylamide and methacrylamide, and any commercially available and industrially used monomers in the form of powder or aqueous solution are sufficient. The amount of these monomers used is 10 to 90 mol%.

In the present invention, in addition to (a) to (c), a crosslinking monomer can also be used as the fourth component. Examples of crosslinkable monomers include monomers having at least two or more double bonds in the molecule and N-alkoxymethyl (meth)acrylamide derivatives. Specific examples of the former include methylene bisacrylamide, diallylacrylamide, triacryl formal, diacryloimide, ethylene glycol acrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1, 4-Butylene glycol dimethacrylate, glycerol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, divinylbenzene, diallyl phthalate, etc. can be used.

The latter N-alkoxymethyl (meth)acrylamide derivatives include N-hydroxymethyl (meth)acrylamide, such as N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-n-butoxymethyl (meth)acrylamide,
N-tert. -Butoxymethyl (meth)acrylamide, etc. can be used. The amount of crosslinking agent used varies depending on the type of crosslinking monomer, but it is usually 0.
．． 0001 to 20 mol %, preferably 0
．． 001 to 10 mol%. 0.0001 m
If it is less than 20 mol%, there is a disadvantage that the paper strength effect cannot be sufficiently expressed, and if it exceeds 20 mol%, there is a disadvantage that gelation occurs.

The method for obtaining the cationic polyacrylamide (B) obtained by polymerizing (a) to (b) of the present invention is a commonly known method used for polymerizing this type of water-soluble vinyl monomer. is used. For example, radical polymerization is preferred as the polymerization method. Monomer concentration is 2-30
The weight percent is preferably 5 to 30 weight percent. The polymerization initiator is not particularly limited as long as it is water-soluble, and it is usually used after being dissolved in an aqueous monomer solution. Specifically, hydrogen peroxide, peroxides such as benzoyl peroxide, persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, bromates such as sodium bromate, potassium bromate, and perborates. Perborate salts such as sodium, potassium perborate, ammonium perborate; percarbonates such as sodium percarbonate, potassium percarbonate, ammonium percarbonate; sodium perphosphate, potassium perphosphate, ammonium perphosphate; Superphosphates such as tert. -butyl peroxide and the like. In this case, it can be used alone, but it can also be used as a redox polymerization agent in combination with a reducing agent. Examples of reducing agents include sulfites, hydrogen sulfites, salts of lower ionization such as iron, copper, and cobalt;
Examples include organic amines such as N,N,N',N'-tetramethylethylenediamine, and reducing sugars such as aldose and ketose.

[0025] Furthermore, as the azo compound, 2,2'-
Azobis-4-amidinopropane hydrochloride, 2,2'-
Azobis-2,4-dimethylvaleronitrile, 4,
4'-Azobis-4-cyanovaleic acid and its salts, etc. can be used. Furthermore, it is also possible to use two or more of the above-mentioned polymerization initiators in combination. In the case of a single polymerization initiator, the polymerization temperature is lower, approximately 30 to 90°C, and in the case of a redox polymerization initiator, it is lower, approximately 30 to 90°C.
The temperature is 5 to 50°C. Further, it is not necessary to maintain the same temperature during the polymerization, and it may be changed as appropriate as the polymerization progresses, and the temperature is generally raised by the polymerization heat generated as the polymerization progresses. The atmosphere inside the polymerization vessel at this time is not particularly limited, but in order to speed up the polymerization, it is better to replace the atmosphere with an inert gas such as nitrogen gas. The polymerization time is not particularly limited, but is approximately 1 to 20 hours. The method of the present invention is used in the process of making paper from pulp, and is highly effective in improving freeness to improve water drainage during paper making and increasing paper strength by increasing the mechanical strength of paper.

In the present invention, Hoffman decomposition PAM (A
) (hereinafter simply referred to as Hoffman decomposition PAM) and cationic polyacrylamide (B) is optional depending on the pulp raw material and white water, but considering the mixing effect, it is 95:5 to 5:95, Preferably 80:20-2
It is 0:80. Further, the method of adding the cationic polyacrylamide is to add Hoffmann-decomposed PAM and cationic polyacrylamide (B) to the pulp slurry individually, or to add the Hoffmann-decomposed PAM and cationic polyacrylamide (B) to the pulp slurry. There is a method of adding it, and any method may be used.

[0027] Even in the combination of Hoffmann-decomposed PAM and cationic polyacrylamide (B), the effect may be further enhanced if sulfuric acid or a water-soluble anionic resin is used in combination. The water-soluble anionic resin used at this time is
Water-soluble resins containing anionic substituents such as carboxyl groups, sulfonic acid groups, phosphoric acid groups, or salts thereof, such as anionic acrylamide resins, anionic polyvinyl alcohol resins, carboxymethyl cellulose, carboxymethyl Examples include converted starch and sodium alginate. There is no particular restriction on the place where it is added, and it can be added to the pulp slurry before, after, or at the same time as the Hoffman-decomposed PAM and cationic polyacrylamide (B). Further, it is also possible to mix it with the Hoffmann-decomposed PAM and the cationic polyacrylamide (B), or with the mixture of the Hoffmann-decomposed PAM and the cationic polyacrylamide (B).

[0028] The addition location may be anywhere before the wet sheet is formed, but it is better to add the agent at a location where the agent is sufficiently diluted and mixed with the pulp slurry and is close to the papermaking wire section. Specifically, the addition location is the machine chest, Select from mixing box, seed box, white water pit, screen outlet, etc. The paper machine used for papermaking may be either a Fourdrinier paper machine or a cylinder paper machine. This papermaking additive has a concentration of 0.5
~5.0%, pH 4.0 ~9.0, temperature 20~7
After being added to the pulp slurry at 0°C, a wet sheet is formed in a wire part, and then water is squeezed out in a press part. Nip pressure in press part is 20-400kg
/cm2. The wet paper that has passed through the press part is moved to the dry part where it is dried by steam. At this time, a steam pressure of 2 to 15 kg/cm2 is used, and drying is performed using a drum at 80 to 200°C. After this, processing using chemicals in a size press or calender for the purpose of improving printability, improving surface strength, and improving water resistance and water repellency is also possible.

[0029] The papermaking additive in the present invention is a water-soluble mixture containing Hoffman decomposition PAM and cationic polyacrylamide (B) as active ingredients, and the concentration of the active ingredients is in the range of 0.001 to 50%. be. Hoffman decomposition PA
The mixing ratio of cationic polyacrylamide (B) to M is 95:5 to 5:95, preferably 80:
20-20:80. If the mixing ratio is too small, the mixing effect will not appear, while if it is too large, the Hofmann decomposition PA
The properties of M will be lost. The Hofmann decomposition rate at that time is not particularly limited, but is approximately 5-60 mol%, preferably 10-50 mol%. The method for mixing Hoffman decomposed PAM and cationic polyacrylamide (B) is as follows:
The pH of the solution after the Hofmann decomposition reaction is usually in the range of 12 to 13, but the pH can be lowered with an inorganic or organic acid before mixing with the cationic polyacrylamide (B). It is also possible to lower the pH after mixing with, and the papermaking additive in the present invention has a pH in the range of 2 to 14.

[0030] By manufacturing according to the method described above,
It becomes possible to improve freeness without causing a decrease in paper strength, specifically bursting strength, Z-axis strength, compressive strength, etc. Therefore, if the method of the present invention is applied to materials such as corrugated cardboard and newspapers, which have a high proportion of waste paper as raw materials, it will be very effective, and it will be possible to produce paper with high paper strength. Furthermore, if the present invention is applied not only to corrugated paper and newspaper, but also to papers that require strength, or when drainage properties are required in the papermaking process, it is possible to manufacture paper with excellent paper strength and strength with good productivity. It becomes possible.

[0031]

EXAMPLES Next, the present invention will be explained by examples, but the present invention is not necessarily limited to the following examples. Note that all percentages are by weight unless otherwise specified.

Production Example 1 675 g of 40% acrylamide (9
4 mol %), dimethylaminoethyl methacrylate 23.1 g (4 mol %), acrylic acid
5.8 g (2 mol %), 62.3 mg (0.01 mol %) of bismethylene acrylamide, and 1,004 g of water were charged, and then the pH was adjusted to 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 ammonium persulfate solution and a 10% aqueous sodium bisulfite solution were added to initiate polymerization. After that, the temperature was kept at 85°C, and 3 hours after the start of polymerization, water was added to complete the polymerization reaction.
A stable cationic polyacrylamide aqueous solution having a nonvolatile content of 15.3%, a Brookfield viscosity of 6,800 cps at 25° C., and a pH of 4.3 was obtained. Production Example 2 10.0wt% polyacrylamide aqueous solution (25℃
Brookfield viscosity: 3,400 cp)
30.0 g was placed in a 500 ml beaker, diluted with 30.0 g of distilled water, and this solution was heated to 80°C with stirring to form a mixed solution of sodium hypochlorite and NaOH (sodium hypochlorite concentration: 1. 0 mol/kg, NaOH concentration: 2.0 mol/kg) was added to 1
After 5 seconds, 225.7 g of cold water at 5 °C was added to stop the reaction, and 1 wt% of acrylamide-based polymer (Hoffmann P
AM(A)) was obtained. A portion of the reaction product was taken in an aqueous solution with a pH of 2, and 1/2 was added using toluidine blue as an indicator.
When colloid titration was performed with a 400 N-potassium polyvinylsulfonate aqueous solution, the cation value was 3.
8 meq. /g. In the following tests, Hoffmann PAM (A) was used immediately after manufacture.

Example 1 Freeness obtained from waste corrugated paper (Canadian Standard Freeness, hereinafter referred to as C.S.F.) 4
A commercially available rosin emulsion sizing agent was added in an amount of 0.15% based on the dry weight of the pulp to 00ml of pulp slurry having a concentration of 1.0%, and the mixture was stirred for 2 minutes. Next, aluminum sulfate was added in an amount of 1.0% on a dry weight basis, and the mixture was further stirred for 1 minute. The pH of the pulp slurry at this time 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, the Hoffmann degradation P obtained in Production Example 4 was added.
AM(A) was added at 0.10% on a dry weight basis. After continuing stirring for another minute, a portion of the resulting pulp slurry was taken and subjected to C.I. according to JIS-P-8121. S
．． F. was measured, and the remaining paper was made using a TAPPI square sheet machine. The paper was then dried for 2 hours in a blow dryer at 110° C. to obtain handmade paper with a basis weight of 125±3 g/m 2 . This handmade paper was tested for "specific compressive strength" according to JIS-P-8126, "specific bursting strength" according to JIS-P-8112, and "specific bursting strength" according to JIS-P-8112 using an internal bond tester manufactured by Kumagai Riki Kogyo. "Z-axis strength" was measured. The results are shown in Table 1.

[0034]

[Table 1]

Example 2 The cationic polyacrylamide obtained in Production Example 1 was added in an amount of 0.20% on a dry weight basis, and the Hofmann-decomposed PAM (A) obtained in Production Example 2 was added in an amount of 0.20% on a dry weight basis. A manual papermaking test was conducted in the same manner as in Example 1 except that % was added. The results are shown in Table 1.

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

Comparative Example 1 The cationic polyacrylamide obtained in Production Example 1 was
．． Hoffman decomposed PA obtained in Production Example 2 by adding 40%
A test similar to Example 1 was conducted except that M(A) was not added. The results are shown in Table 1. Comparative example 2 Manufacturing example 1
The same test as in Example 1 was conducted except that 0.40% of the Hoffmann-decomposed PAM (A) obtained in Production Example 2 was added and the cationic polyacrylamide obtained in Production Example 2 was not added. The results are shown in Table 1.

[0038]

Effects of the Invention As shown in Table 1, the paper made by the method of the present invention surprisingly has a lower freeness than when the Hoffman-decomposed PAM obtained in Production Example 2 was used alone. While maintaining the same level, the specific bursting strength is not affected by the deterioration in formation that would be expected from freeness, and is even higher than when the acrylamide polymer obtained in Production Example 1 or 2 is used alone. Excellent paper strength performance such as specific compressive strength and Z-axis strength. Therefore, when the present invention is applied to the production of paper with excellent strength while maintaining a high level of freeness, great effects can be brought about.

Claims (2)

[Claims] Claim 1: A cationic acrylamide polymer (A) obtained by reacting an acrylamide polymer and a hypohalite under alkaline conditions in a temperature range of 50 to 110°C for a short time; a) General formula (I) (Chemical formula 1
) [Formula 1] (wherein, R1 is hydrogen or a methyl group, R2, R3
is a cationic monomer represented by hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or NH, and n is an integer of 2 to 4), and/or their organic or inorganic acid salts, or Quaternary ammonium salts obtained by the reaction of (I) with a quaternizing agent, (b) α,
β-unsaturated carboxylic acid and or salts thereof, (
c) General formula (II) CH2=C(R5)-CONH2
After adding cationic polyacrylamide obtained by copolymerizing with an acrylamide monomer represented by (II) (wherein R5 represents hydrogen or a methyl group) to the pulp slurry, a wet pulp sheet is formed. A paper manufacturing method characterized by dehydrating the paper using a press and drying it using a dryer. (Claim 2) A cationic acrylamide polymer (A) obtained by reacting an acrylamide polymer and a hypohalite under alkaline conditions in a temperature range of 50 to 110°C for a short time; a) General formula (I) (Chemical formula 2
) [Formula 2] (wherein, R1 is hydrogen or a methyl group, R2, R3
is a cationic monomer represented by hydrogen or an alkyl group having 1 to 6 carbon atoms, X is O or NH, and n is an integer of 2 to 4), and/or their organic or inorganic acid salts, or Quaternary ammonium salts obtained by the reaction of (I) with a quaternizing agent, (b) α,
β-unsaturated carboxylic acid and or salts thereof, (
c) General formula (II) CH2=C(R5)-CONH2
(II) A papermaking additive comprising a cationic polyacrylamide obtained by copolymerizing with an acrylamide monomer represented by (II) (wherein R5 represents hydrogen or a methyl group).