JPH05106194A - Papermaking and additive for papermaking - Google Patents

Abstract

PURPOSE:To make paper excellent in strength while controlling its freeness by adding a specified cationic acrylamide-based polymer in combination with an anionic inorganic substance to a pulp slurry, subsequently forming a wet pulp sheet, pressing and drying it. CONSTITUTION:An additive for papermaking, composed of a cationic acrylamide-based polymer synthesized by reacting an acrylamide-based polymer such as a homo-polymer of acrylamide (or methacrylamide) with a hypohalite (e.g. sodium hypochlorite) in an alkalline condition at 50-110 deg.C for a short time and an anionic substance (preferably sodium silicate) is added to a pulp slurry to prepare a wet pulp sheet. Dehydration treatment is carried out by pressing it and drying treatment is carried out by using a drier, thus affording the objective papermaking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking method and a papermaking additive, and more specifically to high temperature,
A paper-making method characterized in that a cationic acrylamide polymer obtained by a Hoffmann decomposition reaction in a short time is used in combination with an anionic inorganic substance, and a cationic acrylamide polymer obtained by a Hoffman decomposition reaction and an anionic polymer. The present invention relates to a papermaking additive composed of an inorganic substance.

[0002]

2. Description of the Related Art Due to the deterioration of raw material circumstances in recent years, the proportion of waste paper in pulp raw materials tends to increase, and there is a demand for a paper strengthening agent that exhibits a stronger paper strength. On the other hand, in terms of operation, there is a demand for a chemical that improves the drainage rate, a chemical that further improves drainage, and a chemical that improves the dryness because of the requirement to reduce the unit consumption of steam. Hoffman degradation reaction product of polyacrylamide (Hoffman PAM) is a cationic resin having a primary amino group directly bonded to the polymer main chain,
Conventionally, it has been used as a drainage improver and a paper strength enhancer in the paper manufacturing process. However, Hofmann PAM obtained by reacting with hypohalite in an alkaline region at high temperature for a short period of time has a cationic property in an aqueous solution, as in the case of a conventional low temperature / long time reaction. The present inventors have found that the problem of deterioration over time, that is, disappearance, can be solved, and that its excellent characteristics can be utilized. The characteristic of Hoffman PAM lies in the strength of the cohesive force, but not only improves drainage but also improves the strength between fibers due to the hydrogen bond of the primary amino group which is also a cation group.

[0003]

However, when Hoffman PAM is used alone as described above, effective fixing to pulp fibers may not be achieved depending on the papermaking conditions, and the characteristics of Hoffman PAM are fully exerted. The present inventors have found that there are some things that cannot be done. In such a case, increasing the amount of Hoffman PAM can solve the problem in terms of drainage, but since the texture of the paper is disrupted, satisfactory results are obtained in terms of paper strength and printing characteristics. I found that I could not. In view of the above points, the present inventors have studied various additives having a Hofmann-decomposed PAM and a combined addition effect, and as a result, by adding the anionic inorganic substance together, the paper strength performance is not deteriorated, The inventors have found that the drainage can be controlled and have reached the present invention.

[0004]

The present invention provides an acrylamide polymer and a hypohalite in an alkaline region,
A method for making paper, characterized in that a cationic acrylamide polymer obtained by carrying out a reaction in a short time in a temperature range of 50 to 110 ° C. and an anionic inorganic substance are used in combination and added to a pulp slurry, and , An acrylamide polymer and a hypohalite in an alkaline region,
The present invention relates to a papermaking additive composed of a cationic acrylamide polymer obtained by carrying out a reaction in a temperature range of 110 ° C for a short time and an anionic inorganic substance.

The present invention will be described in detail below. The acrylamide polymer used in the present invention means a homopolymer of acrylamide (or methacrylamide), or a copolymer of acrylamide (or methacrylamide) and one or more unsaturated monomers copolymerizable with acrylamide (or methacrylamide), Means a graft copolymer to a water-soluble polymer such as starch.
Examples of the copolymerizable monomer include a hydrophilic monomer, an ionic monomer, a lipophilic monomer and the like, and one or more kinds of these monomers can be applied.

Specific examples of the hydrophilic monomer include diacetone acrylamide, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N-ethyl methacrylamide, N-ethyl acrylamide and N, N-diethyl amide. Acrylamide, N-propylacrylamide, N-
Acryloylpyrrolidine, N-acryloylpiperidine, N-acryloylmorpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxy polyethylene glycol (meth) acrylates, N-vinyl-2-pyrrolidone, etc. You can

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

Examples of lipophilic monomers include N, N-di-
n-propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide, Nn-hexylmethacrylamide, Nn-octylacrylamide, Nn-octylmethacrylamide, N-tert-
N-alkyl (meth) acrylamide derivatives such as octyl acrylamide, N-dodecyl acrylamide, N-n-dodecyl methacrylamide, N, N-diglycidyl acrylamide, N, N-diglycidyl methacrylamide, N- (4-glycid 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,
Examples thereof include styrene, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like. 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 generally stated, but it is generally in the range of 0 to 50% by weight.

As the water-soluble polymer for graft-copolymerizing the above-mentioned monomers, both natural and synthetic ones can be used. Modified products such as starch and oxidized starch, carboxy starch, dialdehyde starch, cationized starch and the like derived from various sources as a natural system; methyl cellulose, ethyl cellulose, carboxymethyl cellulose,
Cellulose derivatives such as hydroxyethyl cellulose; alginic acid, agar, pectin, carrageenan, dextran, pullulan, konjac, gum arabic, casein,
Examples include gelatin. 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 above-mentioned monomer added to the above water-soluble polymer is in the range of 0.1 to 10.0 times based on the water-soluble polymer.

Next, the above-mentioned monomers are polymerized to produce an acrylamide polymer. Radical polymerization is preferred as the polymerization method, and polar solvents such as water, alcohols, and dimethylformamide can be applied as the polymerization solvent, but aqueous solution polymerization is preferred because the Hofmann decomposition reaction is carried out in an aqueous solution. At that time, the monomer concentration is 2 to 30% by weight, preferably
It is 5 to 30% by weight. The polymerization initiator is not particularly limited as long as it is water-soluble, and it is usually used by dissolving it in an aqueous monomer solution. Specifically, examples of the peroxide type include ammonium persulfate, potassium persulfate, hydrogen peroxide, and tert-butyl peroxide. In this case, although it can be used alone, it can also be used as a redox polymerizing agent in combination with a reducing agent. As the reducing agent, for example, sulfite, bisulfite, iron, copper, low-order ionization salts such as cobalt, N, N, N ', N'-organic amines such as tetramethylethylenediamine, further aldose, ketose. And reducing sugars such as

As the azo compound, 2,2'-azobis-2-amidinopropane hydrochloride, 2,2'-azobis-2,
4-Dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid and salts thereof and the like can be used.
Furthermore, it is possible to use two or more of the above-mentioned polymerization initiators in combination. In addition, in the case of graft polymerization to a water-soluble polymer, other than the above-mentioned polymerization initiator, a second
It is also possible to use transition metal ions such as cerium ion and ferric ion, and they 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.
% By weight, preferably 0.02 to 8% by weight. In the case of a redox system, the amount of the reducing agent added to the initiator is 0.1 to 100%, preferably 0.2 to 80% on a molar basis. The polymerization temperature is about 30 to 90 in the case of a single polymerization initiator.
C., which is lower in the case of a redox type polymerization initiator, and is generally -5 to 50.degree. Further, it is not necessary to keep the same temperature during the polymerization, and it may be appropriately changed as the polymerization progresses, and generally the temperature is raised by the heat of polymerization generated as the polymerization progresses. The atmosphere in the polymerization vessel at that time is not particularly limited, but it is preferable to replace with an inert gas such as nitrogen gas in order to carry out the polymerization rapidly. The polymerization time is not particularly limited, but is generally 1 to 20 hours.

Next, the Hoffmann decomposition reaction of the acrylamide polymer produced by the above method is performed. At this time, when the polyacrylamide as a raw material is produced in an aqueous solution, it can be used for the reaction as it is or after being diluted if necessary. In the case of a graft copolymer,
Although non-grafted polyacrylamide is also produced as a by-product, it is usually used as it is without being separated.

The Hoffmann decomposition reaction is carried out by reacting a hypohalite with an amide group of polyacrylamide in the presence of an alkaline substance. As hypohalous acid, hypochlorous acid, hypobromite, Examples include iodic acid.
Examples of the hypochlorite include metal or alkaline earth metal salts of hypochlorous acid, and specifically, sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, hypochlorous acid. Examples include calcium, magnesium hypochlorite, and barium hypochlorite. Similarly, hypobromite and hypoiodite include alkali metal or alkaline earth metal salts of hypobromite and hypoiodite. It is also possible to blow a halogen gas into the alkaline solution to generate hypohalite. On the other hand, examples of the alkaline substance include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates and the like. Among them, alkali metal hydroxides are preferable, and sodium hydroxide, potassium hydroxide, hydroxide Examples include lithium. The amount of the above substances added to polyacrylamide is 0.05 to 2.0 mol, preferably 0.1 to 1.5 mol, with respect to the amide group in hypohalous acid, and 0.05 to 4.0 mol, preferably, 0.1 to 1.5 mol with respect to the amide group in alkaline substances. 0.1
~ 3.0 mol. The pH at that time is in the range of about 11-14. At that time, the concentration of polyacrylamide was almost zero.
Although it is 1 to 17.5% by weight, it is usually preferable to be in the range of 0.1 to 10% by weight from the viewpoint that stirring becomes difficult and gelation easily occurs when the reaction concentration becomes high. Also,
If the reaction concentration is less than 1%, there is a problem such as a slow reaction rate, so 1 to 10% by weight is more preferable.

The reaction temperature is in the range of 50 to 110 ° C.,
It is preferably in the range of 60 to 100 ° C. Next, the Hoffmann decomposition reaction is carried out in a short time within the above-mentioned temperature range. However, the reaction time depends on the reaction temperature and the polymer concentration in the reaction solution, and therefore cannot be said unconditionally. %, Within 10 minutes at 50 ° C, 65 ° C
Within a few minutes and at 80 ° C. within a few tens of seconds are sufficient. Furthermore, the higher the polymer concentration, the shorter the reaction time. In the above concentration range, the relationship between the reaction time and the reaction temperature should be roughly within the range between the following two relational expressions (1), (2) (Equation 1), and the concentration should be considered within the range. If the reaction is carried out in this way, suitable results can be obtained.

[0015]

## EQU1 ## 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 produced under the above-mentioned conditions has a cation equivalent in the range of 0 to 10.0 meq / g as measured by colloid titration at pH 2, which depends on the amount of hypohalite added. The cation equivalent can be controlled. Moreover, since the reaction is carried out in the alkaline region, the amide group is hydrolyzed and a carboxyl group is produced as a by-product. The by-product amount is indicated by anion equivalent measured by colloidal titration at pH 10, and is generally 0 to 10.0 meq / g.
Is in the range. The amount of the by-product can be controlled by the amount of the alkaline substance added.

After the reaction is performed under the above conditions, it is preferable to stop the reaction in order to suppress the progress of side reactions. However, when used for papermaking immediately after the reaction, the reaction may not be stopped. As a method of stopping the reaction, methods such as (1) adding a reducing agent, (2) cooling, (3) lowering the pH of the solution by adding an acid, etc. can be used alone or in combination.
The method (1) is a method of deactivating the residual hypohalite by reacting with a reducing agent. Generally, at the end of the Hoffman decomposition reaction, unreacted compounds having active chlorine such as hypohalite remain. When such a reaction solution is used as a paper-strengthening agent, it also causes rust in a paper machine. Therefore, a reducing agent is usually used to deactivate active chlorine. However, the hypohalite reacts in an equimolar amount or less with respect 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. We found that. Therefore, it is also possible to use it as a paper strength agent without deactivating active chlorine by using a reducing agent.
(2) is a method of suppressing the progress of the reaction by cooling, and as a method thereof, there are 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 Huffman decomposition reaction is stopped by lowering the pH of an alkaline reaction solution having a pH of 12 to 13 at the end of the reaction, 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.

Hoffman-decomposed PA produced by the above method
The anionic inorganic substance added together with M is sodium silicate,
It is an anionic particulate inorganic material or a mixture thereof. Sodium silicate is obtained by melting silicon dioxide and sodium carbonate or caustic soda at a high temperature, and those commercially available as water glass can be used. The structure is represented by the following general formula,

[0019]

[Chemical formula 1] NaO · nSiO ₂ · xH ₂ O

N is 1 to 4, and specific examples thereof include sodium metasilicate, sodium orthosilicate, No. 1, No. 2 and No. 3 water glasses. As for the shape, flakes, powder, etc. may be dissolved in water and used, or those sold as an aqueous solution may be used. As the anionic particulate inorganic substance, any substance that is water-insoluble and is anionically charged in water may be used, and various substances can be used. Specifically, for example, silicon dioxide, aluminum oxide, antimony oxide, titanium oxide, and oxides of clay minerals such as alumina silicates such as montmorillonite, bentonite, kaolin, activated clay, silica sand, diatomaceous earth, and magnesia silicate such as talc. Furthermore, carbonates such as calcium carbonate and the like can be mentioned. If the size of the above-mentioned particles is too large, the composite effect becomes small, and the particle size is generally 100 μm or less, preferably 50 μm or less, and more preferably 10 μm or less.

The combined addition ratio of the Hoffman-decomposed PAM and the anionic inorganic substance is 1-500%, preferably 2-400%, and more preferably 3-300% by weight based on the Hoffman-decomposed PAM. If the combination ratio is too small,
If the combined effect does not appear, on the other hand, if too many, Hoffman decomposition P
The property of AM is impaired. The Hoffman decomposition rate at that time is not particularly limited, but is generally 5 to 60 mol%, preferably 10 to 50 mol%.

A specific method is to add an anionic inorganic substance together. The Hoffman-decomposed PAM used in the present invention is used.
Reacts at high temperature for a short time and can be added and used as it is. Since the reaction solution at that time is strongly alkaline, it can be added together by any method. Specifically, (i) when carrying out the Hoffman decomposition reaction, caustic soda, sodium hypochlorite or a mixed solution thereof is added and dissolved in advance, and the Hoffman decomposition reaction is carried out using it.
There are i) addition to the reaction solution after the Hoffman decomposition reaction, and (iii) individual addition.

In the present invention, the addition ratio of the Hoffman-decomposed PAM and the anionic inorganic substance to the pulp is generally in the range of 0.005-5.0%, preferably 0.01-2.0%, based on the dry weight of the pulp. Further, at that time, the ratio of the Hoffman-decomposed PAM and the anionic inorganic substance varies depending on the papermaking conditions. Specifically, for example, when the drainage is increased to increase the papermaking speed, the ratio of the anionic inorganic substance is reduced,
On the other hand, when the formation structure is adjusted and the purpose is to produce homogeneous paper, the addition ratio may be increased. In the method of the present invention, the combined use of a sulfuric acid band or a water-soluble anionic resin may further enhance the effect. The water-soluble anionic resin used at this time is a carboxyl group, a sulfonic acid group,
A water-soluble resin containing an anionic substituent such as a phosphoric acid group or a salt thereof, for example, anionic acrylamide resin, anionic polyvinyl alcohol resin, carboxymethyl cellulose, carboxymethylated starch, sodium alginate. Etc. can be mentioned. The place of addition is not particularly limited, and Hoffman-decomposed PA
M and sodium silicate can be added to the pulp slurry before or after the addition to the pulp slurry. It is also possible to mix with each of Hoffman-decomposed PAM and sodium silicate, or to mix them.

The place of addition may be any place before the formation of the wet sheet, and it is better to add the drug in a place which is sufficiently diluted and mixed with the pulp slurry and close to the papermaking wire part, specifically, machine chest, It is selected from mixing box, seed box, white water pit, screen exit, 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-
After addition to the pulp slurry at 5.0%, pH 4.0-9.0 and temperature 20-70 ° C, a wet sheet is formed in the wire part and then water is pressed in the press part. The nip pressure in the press part is in the range of ^{20 to} 400 kg / 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 to 15 kg / c
It is dried by a drum of 80 to ²⁰⁰ ° C. using m2. After that, processing with a chemical for the purpose of improving printability, surface strength, water resistance and water repellency in a size press or a calendar is also possible.

The papermaking additive in the present invention is a water-soluble mixed solution containing Hofmann-decomposed PAM and an anionic inorganic substance as an active ingredient, and the active ingredient concentration is 0.001 to 50%.
Is in the range. The mixing ratio of the anionic inorganic substance to the Hoffman-decomposed PAM is 1-500% by weight, preferably 2-400%, more preferably 3-300%.
If the mixing ratio is too small, the mixing effect does not appear. On the other hand, if the mixing ratio is too large, the properties of the Hoffman-decomposed PAM are deteriorated. The Hoffman decomposition rate at that time is not particularly limited, but is generally 5 to 60 mol%, preferably 10 to 50 mol%.
As a method for mixing the Hoffmann-decomposed PAM and the anionic inorganic substance, (i) when carrying out the Hoffman decomposition reaction, add and dissolve it in caustic soda, sodium hypochlorite or a mixture thereof in advance and use it. Or (ii) mixing with the reaction solution after the Hoffmann decomposition reaction. The pH of the solution after the Hoffman decomposition reaction is usually 1
Although it is in the range of 2 to 13, the pH can be lowered with an inorganic acid or an organic acid before mixing with the anionic inorganic substance, and the pH can be lowered after mixing with the anionic inorganic substance. The additive for papermaking in
It is in the range of 14.

By manufacturing by the above method,
It is possible to improve drainage without causing reduction in paper strength, specifically burst strength, Z-axis strength, compression strength and the like. Therefore, when the method of the present invention is applied, it is very effective when used for raw materials such as corrugated board and newsprint having a high ratio of used paper, and it becomes possible to produce paper with high paper strength. Further, not limited to corrugated cardboard and newspaper, if the present invention is applied to paper that requires strength or drainage is required in the paper making process, it is possible to produce paper with excellent productivity and paper strength. It will be possible.

[0027]

EXAMPLES The present invention will now be described by way of examples, but the present invention is not necessarily limited to the following examples. Unless otherwise specified, all the percentages are% by weight.

Production Example 1 24.0 g of a 10.0 wt% polyacrylamide aqueous solution (Brookfield viscosity at 25 ° C .: 3,400 cps) was placed in a 500 ml beaker, diluted with 36.0 g of distilled water, and the solution was heated to 80 ° C. with stirring. A mixed solution of sodium hypochlorite and NaOH (sodium hypochlorite concentration: 1.0 mol / kg, NaOH
(Concentration: 2.0 mol / kg) was added 14.8 g, and 15 seconds later, 225.2 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 having a pH of 2, and colloid titration was performed with a 1/400 N-potassium polyvinylsulfonate aqueous solution using toluidine blue as an indicator, and the cation value was 4.4 meq./g. In the following tests, Hoffman PAM (A) was used immediately after production.

Production Example 2 24.0 g of a 12.5 wt% polyacrylamide aqueous solution (Brookfield viscosity at 25 ° C .: 12,400 cp) was placed in a 500 ml beaker, diluted with 36.0 g of distilled water, and the solution was stirred at 20 ° C. , 14.8 g of a mixed solution of sodium hypochlorite and NaOH (sodium hypochlorite concentration: 1.0 mol / kg, NaOH concentration: 2.0 mol / kg) was added, and 2 hours later, 225.2 g of 0.001% sodium sulfite aqueous solution was added. To stop the reaction,
1 wt% of an acrylamide polymer was obtained (hereinafter referred to as Hoffman PAM (B)). Part of the reaction product was taken up in an aqueous solution of pH 2 and 1/400 N was added using toluidine blue as an indicator.
-As a result of colloidal titration with an aqueous solution of potassium polyvinyl sulfonate, the cation value was 4.4 meq./g.

Example 1 Beating degree obtained from waste corrugated cardboard (Canadian Standard Freeness, hereinafter referred to as CSF) 450 ml of a pulp slurry having a concentration of 1.0% and a commercially available rosin emulsion sizing agent of 0.15 with respect to pulp on a dry weight basis. % And stirred for 2 minutes. Then, 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. Then, 0.30% of No. 3 water glass was added on a dry weight basis, and after stirring for 1 minute, 0.60% of Hoffman PAM (A) obtained in Production Example 1 was added on a dry weight basis. After stirring for 1 minute, a part of the obtained pulp slurry was taken, CSF was measured according to JIS-P-8121, and the rest was paper-made by a TAPPI square sheet machine. Then use a blast dryer at 110 ° C for 2
After drying for an hour, a handmade paper having a basis weight of 150 ± 3 g / m ² was obtained. This handmade paper has a "specific compression strength" according to JIS-P-8126
According to SP-8112, "specific burst strength" and "Z-axis strength" were measured using an internal bond tester manufactured by Kumagai Riki Kogyo. The results are shown in Table 1.

[0031]

[Table 1]

Example 2 A handmaking test was conducted in the same manner as in Example 1 except that 0.63% of No. 3 water glass was added on a dry weight basis. The results are shown in Table 1. Example 3 A hand-making test was conducted in the same manner as in Example 1 except that 0.90% of No. 3 water glass was added on a dry weight basis. The results are shown in Table 1. Example 4 A hand making test was conducted in the same manner as in Example 1 except that 1.50% of No. 3 water glass was added on a dry weight basis. The results are shown in Table 1.

Comparative Example 1 A hand-making test was conducted in the same manner as in Example 1 except that 0.003% of No. 3 water glass was added on a dry weight basis. The results are shown in Table 1. Comparative Example 2 A hand-making test was performed in the same manner as in Example 1 except that 5.00% of No. 3 water glass was added on a dry weight basis. The results are shown in Table 1. Comparative Examples 3 and 4 A hand-made test was conducted in the same manner as in Comparative Examples 2 and 4 except that the Hoffman PAM (A) used in Comparative Examples 1 and 2 was replaced with Hoffman PAM (B). The results are shown in Table 1.

Example 5 0.5% by weight of aluminum sulfate was added to a pulp slurry having a beating degree (Canadian Standard Freeness, CSF) 543 ml of a concentration of 1.0% obtained from waste corrugated cardboard and stirred for 1 minute. .. The pH of the pulp slurry at this time was 5.8. Next, 0.25% of colloidal silica (Snowtex 40, particle size 10 to 20 nm, manufactured by Nissan Chemical Industries, Ltd.) was added on a dry weight basis, and after stirring for 30 seconds, the Hoffman PAM (A) obtained in Production Example 1 was used on a dry weight basis. 1.50% was added. Take a portion of the pulp slurry obtained after stirring for a further 30 seconds, JIS-P-8121
The CSF was measured in accordance with the above, and the rest was made with a TAPPI square sheet machine. Then, it was dried for 2 hours with a blower dryer at 110 ° C. to obtain a handmade paper having a basis weight of 150 ± 3 g / m ² . This handmade paper uses "Specific compression strength" according to JIS-P-8126, "Specific burst strength" according to JIS-P-8112 and "Internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd." The "Z-axis strength" was measured. The results are shown in Table 2.

[0035]

[Table 2]

Example 6 A hand-making test was conducted in the same manner as in Example 5 except that 0.50% of colloidal silica was added on a dry weight basis. The results are shown in Table 2. Example 7 A hand making test was conducted in the same manner as in Example 5 except that 1.00% of colloidal silica was added on a dry weight basis. The results are shown in Table 2. Comparative Example 5 A hand-making test was conducted in the same manner as in Example 5 except that 0.001% of colloidal silica was added on a dry weight basis. The results are shown in Table 2. Comparative Example 6 A hand-making test was conducted in the same manner as in Example 5 except that 10.0% of colloidal silica was added on a dry weight basis. The results are shown in Table 2.

[0037]

As shown in Tables 1 and 2, the paper prepared by the method of the present invention has the drainage property changed by the addition of the anionic inorganic substance. It showed a tendency to be improved rather by addition. When an appropriate amount of anionic inorganic substance is present, Hoffman P
It is presumed that in order to reduce the cohesive force of AM to an appropriate degree, it shifts to the direction of forming the texture and becomes excellent in paper strength performance such as specific burst strength, specific compressive strength, and Z-axis strength. This effect is particularly remarkable in the case where the Hoffmann decomposition reaction is carried out in a temperature range of 50 ° C. to 110 ° C. for a short time, and its action mechanism is not completely clear at present, but an anionic inorganic substance is used. Thus, it is clear that the paper strength effect of PAM that has undergone the Hoffman decomposition reaction at high temperature for a short time can be significantly enhanced. Therefore, even if the drainage is sacrificed to some extent, the present invention is applied to a case where the texture is adjusted and paper having excellent strength is produced, and a great effect is brought about.

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Claims (4)

[Claims] 1. A cationic acrylamide polymer obtained by reacting an acrylamide polymer and hypohalite under alkaline conditions in a temperature range of 50 to 110 ° C. for a short time, and an anionic inorganic substance. A method for making paper, characterized in that a wet pulp sheet is formed after both and are added to a pulp slurry, dehydrated by a press, and dried by a dryer. 2. A cationic acrylamide polymer and an anionic inorganic substance obtained by reacting an acrylamide polymer and hypohalite under alkaline conditions in a temperature range of 50 to 110 ° C. for a short time. An additive for papermaking. 3. The method for making paper according to claim 1, wherein the anionic inorganic substance is sodium silicate. 4. The papermaking additive according to claim 2, wherein the anionic inorganic substance is sodium silicate.