JPH0457991A - Additive for paper-making process - Google Patents

Abstract

PURPOSE:To obtain the subject cationic additive having excellent paper strength and freeness compared with conventional additives by using polyacrylamides having high molecular weight and low molecular weight at a specific ratio and reacting the polymers with a hypohalite under alkaline condition. CONSTITUTION:The objective additive can be produced by reacting polyacrylamides containing (A) 50-99.8% of a polyacrylamide having a weight- average molecular weight of 50,000-500,000 and (B) 0.2-50% of a polyacrylamide having a weight-average molecular weight of 500,000-20,000,000 with a hypohalite (e.g. sodium hypohalite) under alkaline condition. The reaction of the polyacrylamide and the hypohalite is carried out preferably at 50-110 deg.C. The reaction system is alkalized preferably by using an alkali metal hydroxide such as KOH.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to papermaking additives used in the papermaking industry. More specifically, the papermaking additive includes:
Because it is less susceptible to the effects of inorganic salts and soluble organic substances contained in the white water of the papermaking process, it exhibits a remarkable paper strength enhancement effect and drainage improvement effect compared to other papermaking additives. There is.

The present invention relates to a method for providing the papermaking additive, and a method for increasing paper strength and improving drainage using the papermaking additive.

[Problems to be solved by conventional techniques and inventions] In recent years,
Global environmental destruction is becoming a problem all over the world. In particular, it has been suggested that the depletion of the ozone layer, the increase in carbon dioxide concentration, and even the desertification of the earth's surface in tropical regions have a major impact on the survival of life on Earth. Up until now, economic growth has been the top priority, but now seems to be the time to seriously think about the coexistence of nature and humans. Under these circumstances, there is a worldwide trend to reconsider the logging of forests, which are collections of plants that fix carbon dioxide gas. In other words, attention is being paid to the importance of forest resources. on the other hand,
Fast-growing varieties such as eucalyptus, acacia, and poplar are being planted on areas where forests have been cleared, but the land in the Netsatsu region is not very fertile, and tree species suitable for each area have not been established. Currently, there are various obstacles such as the tendency to use logging sites as agricultural land or grazing land, and the current situation is that the forestry industry does not have a sufficient economic base. Against this background, it is easy to predict that the raw wood used in the paper industry will become even more difficult to obtain from now on than it is now.

On the other hand, with the spread of OAm machines in developed countries, paper consumption is increasing compared to before, and high quality paper is being demanded. As a result of this, the amount of paper waste in waste has increased significantly, and the capacity of processing plants has become strained.

Here, since wood resources are reusable resources,
Paper reuse, that is, the use of waste paper, is attracting attention from the perspective of protecting forest resources. In fact, government agencies have led calls for the use of recycled paper and an increase in the mixing ratio of used paper, and the current situation is that each paper manufacturer is responding to this demand. In other words, in the paper industry, the use of waste paper is a social need. However, from a technical point of view, increasing the mixing ratio of waste paper means increasing the number of valve fibers that have been subjected to mechanical shearing forces many times. That is, by using such damaged valve fibers, a decrease in paper strength is unavoidable, and moreover, as the number of fine fibers increases, the freeness tends to clearly deteriorate.

Also, in the paper industry as a whole, is it a good idea to make paper machines closed with white water in order to reduce wastewater? It's getting louder. Although closed white water is very effective in reducing water pollution, the quality of water used in the papermaking process is significantly reduced as white water becomes closed. Due to this influence, the effectiveness of paper strength enhancers is currently decreasing.

As described above, the current paper manufacturing industry is under very strict conditions in terms of raw materials and operations, but the current situation is that users are demanding products of higher quality than current products. be. For this reason, the paper industry continues to make unremitting efforts in research and technological development. However, as long as there are restrictions on raw materials, the need for various chemicals in the papermaking process will continue to increase in the future.

In fact, among the various papermaking chemicals, paper strength agents in particular have come to play a more important role than ever before. That is, there has been a demand for a papermaking agent that has a higher paper strength enhancement effect than conventional ones, has a higher paper drainage improvement effect, and is easy to handle.

Conventionally used paper strength enhancers include acrylamide-based polymers such as anionic polyacrylamide, amphoteric acrylamide obtained by modification by Mannich reaction or Hoffmann reaction, or amphoteric polyacrylamide obtained by copolymerization. There are modified starches such as coalesced, oxidized starch, pregelatinized starch, cationized starch, dialdehyde starch, shrimp chlorohydrin modified products of polyamide polyamine, etc., and these can be added alone or in combination of two or more to the pulp slurry during the papermaking process. has been used.

(Hereinafter, acrylamide-based polymers and copolymers will be simply referred to as polyacrylamide.) Among the above, Hofmann-degraded polyacrylamide has advantages that Mannich-modified polyacrylamide and amphoteric polyacrylamide obtained by copolymerization with cationic monomers do not have. Although it has characteristics such as increasing paper strength and improving drainage, it has the problem of deterioration over time, in which its cationic nature disappears over time in an aqueous solution.
It has not yet been widely put into practical use.

Conventionally, various studies have been made to improve this point. One of these attempts is to perform the Hofmann decomposition reaction of polyacrylamide at a low temperature to suppress side reactions and thereby suppress deterioration over time. In other words, in 1976, it was pointed out that in the Hofmann decomposition reaction of polyacrylamide, conversion to amine groups easily occurs even at low temperatures due to the reaction promoting effect of adjacent groups. It has been disclosed that in order to obtain high-performance aminated PAM, it is desirable to conduct the reaction at a low temperature of approximately 25°C or less in order to suppress side reactions (hydrolysis, lactam ring formation, etc.) and depolymerization. There is. Similarly, the advantage of conducting the Hofmann decomposition reaction of polyacrylamide at low temperatures is described in JP-A-81-200103. It is also described in JP-A-58-152004, JP-A-58-108206, JP-A-57-185404, JP-A-55-6558, JP-A-52-152493, JP-A-51-122188, etc. However, simply carrying out the Hofmann decomposition reaction at a low temperature does not improve the change over time to a level that can withstand practical use. Another method is to coexist a hydroxyl-substituted compound with a cationic group such as a quaternary ammonium salt, or an N,N-dialkyl-substituted diamine, guanidine, polyamine, etc. during the Hofmann decomposition reaction. The idea of preventing the change over time by reacting the substance with the isone-i, -to group, which is a polymer, and incorporating the substance into the polymer was proposed in JP-A-62.
-59602, JP-A-61-120807, JP-A-57
-192408, JP-A-58-144295, JP-A-5
4-145790, JP-A-53-109594, etc.

Furthermore, the present inventors have found that by extremely shortening the reaction time in the high-temperature reaction of Hofmann decomposition,
We have discovered that it is possible to produce cationic polyacrylamide with properties equivalent to or superior to those of Hoffmann-decomposed polyacrylamide produced by low-temperature reaction, and have reported that a completely new system for producing cationic polyacrylamide has become possible. There is. Furthermore, by utilizing this manufacturing system, it is possible to avoid the problem of aging deterioration of Hoffmann-decomposed polyacrylamide, making it possible to apply it in a wide range of fields.

However, even with the papermaking additives obtained using this method, it cannot be said that they will be fully satisfactory considering the severe social situation surrounding the papermaking industry as mentioned above. be.

[Means for Solving the Problems] In view of the above points, the present inventors investigated the Hofmann decomposition reaction of polyacrylamide in more detail, and as a result, the average molecular weight of polyacrylamide, which is the base when performing the Hofmann decomposition reaction, was determined. We focused on the fact that this affects the performance of the obtained product. That is, when the average molecular weight of the polyacrylamide used in the Hofmann decomposition reaction is manipulated and a combination of high molecular weight and low molecular weight H is used as a base polymer, it can be obtained by conventional methods. The inventors have discovered that it is possible to produce a cationic polyacrylamide that has effects on paper strength and freeness that are equal to or higher than those of Hoffmann-decomposed polyacrylamide, leading to the present invention.

That is, the present invention uses 50 to 99.8% of polyacrylamide having a weight average molecular weight in the range of 50,000 to 500,000 in a Hoffman decomposition reaction in which an acrylamide polymer is reacted with a hypohalite in an alkaline region. The present invention relates to a papermaking additive characterized by using polyacrylamide containing 0.2 to 50% of polyacrylamide having a weight average molecular weight in the range of 500,000 to 20,000,000. The present invention also relates to a method for obtaining unprecedented paper strength enhancement effects and drainage improvement effects using the papermaking additive obtained by the present invention.

[Specific conditions for carrying out the invention]

The present invention will be explained in detail below.

The polyacrylamide-based polymer used in the present invention is a homopolymer of acrylamide (or methacrylamide) or a copolymer with one or more unsaturated monomers copolymerizable with acrylamide (or methacrylamide), and 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-acryloylmorboline,
Hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol (meth)acrylates, N-vinyl-2
- Examples include pyrrolidone.

Examples of the ionic monomer include acrylic acid, methacrylic acid, nyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, and 2-acrylamide-2- Acids such as methylpropanesulfonic acid and their salts, NN-dimethylaminoethyl methacrylate, NJ
Examples include amines and salts thereof such as I-diethylamine ethyl methacrylate, N,N-dimethylahanoethyl acrylate, N,N-dimethylaminoflobil methacrylamide, and N,N-dimethylaminoflobil acrylamide.

Examples of the lipophilic monomer include N,N-di-n-furopylacrylamide, N-n-butylacrylamide, N
-n-hexyl acrylamide, N-n-hexyl methacrylamide, N n-octylacrylamide, N
-n-octyl methacrylamide, N-tert-octylacrylamide, N-dodecyl acrylamide, N
N-alkyl (meth)acrylamide derivatives such as -n-dodecyl methacrylamide, N,N-diglycidyl acrylamide, N,N-diglycidyl methacrylamide,
N-(4-glycidoxybutyl)acrylamide, N-
(4-glycidoxybutyl)methacrylamide, N-(
5-glycidoxypentyl)acrylamide, N-(6
-N-(ω
-glycidoxyalkyl)(meth)acrylamide derivatives, methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, lauryl(meth)ac! jL/-t+ (meth)acrylate derivatives such as 2-ethylhexyl (meth)acrylate and glycidyl (meth)acrylate, olefins such as acrylonitrile, methacrylaterile, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene, butene, Styrene, divinylbenzene, α-methylstyrene,
Butadiene, isoprene, etc. can be mentioned. The amount of the unsaturated monomer used in the copolymerization varies depending on the type of unsaturated monomers and their combination, and 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. Starch and oxidized starch derived from various natural sources,
Modified products such as carboxyl starch, dialdehyde starch, cationized starch, cellulose derivatives such as methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, alginic acid, agar, pectin, carrageenan, dextran, flurane, konjac, gum arabic, casein, gelatin etc. can be mentioned. 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 in the range of 0.1 to 10.0 times based on the water-soluble polymer.

Next, the above monomers are polymerized to produce polyacrylamide. Radical polymerization is preferred as the polymerization method, and polar solvents such as water, alcohol, and dimethylformamide can be used as the polymerization solvent. Since the Hofmann decomposition reaction is carried out in an aqueous solution, aqueous solution polymerization is preferred. At that time, the monomer concentration is 2 to 30%, preferably 5 to 30%.
It is 30% by weight.

There are no particular limitations on the polymerization initiator as long as it is water-soluble. 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; Examples include 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 used in redox polymerization include sulfites, hydrogen sulfites, salts of lower ionization such as iron, copper, and cobalt, organic amines such as N, N, N', N'-tetramethylethylenediamine, Further examples include reducing sugars such as aldose and ketose.

In addition, as an azo compound, 2,2'-azobis-4-
Amidinopropane hydrochloride, 2,2'-azobis-2,4
-dimethylvaleronitrile, 4.4°-azobis-4-
Ciatsuvaleic 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, in the case of graft polymerization to a water-soluble polymer, it is also possible to use transition metal ions such as ceric ions and ferric ions as a polymerization initiator in addition to the above-mentioned polymerization initiators. It may be used in combination with the polymerization initiator described above.

The amount of the initiator added is 0.01 to 10%, preferably 0.02 to 8% by weight, based on the monomer. In addition, in the case of the Rezox system, the amount of reducing agent added to the initiator is 0.1 to 200% by weight on a molar basis, preferably 0.2 to 200% by weight.
15, 1%.

In the case of a single polymerization initiator, the polymerization temperature is approximately 10 to 90
°C, and in the case of a redox polymerization initiator, it is lower, approximately 5 to 50 °C. Further, it is not necessary to maintain the temperature at a 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. There is no particular limitation on the polymerization time, but it is generally 1 to 2
It is 0 hours.

Regarding the weight average molecular weight of the acrylamide polymer thus obtained, the distribution of this MfM average molecular weight is a very important point in the present invention. That is, 50 to 99.8%, preferably 70 to 99.8%, of polyacrylamide having a MIl weight average molecular weight in the range of 50,000 to 500,000.
Using a base polymer containing 0.2 to 50%, preferably 5 to 30%, of polyacrylamide having a weight average molecular weight of 500,000 to 20,000,000, the Hofmann decomposition reaction described below is carried out. It is essential to do so.

The inventors have yet to fully elucidate the detailed mechanism by which polarizing the weight average molecular weight of the base polymer used in this Hofmann decomposition reaction exhibits a superior effect to conventional papermaking additives. However, the moderate amount of high molecular weight polyacrylamide probably aggregates the pulp fibers to form a moderate floc.
It is predicted that the freeness will be improved and the Z-axis strength will also be improved. In addition, polyacrylamide with a weight average molecular weight in the range of 50,000 to 500,000, which is normally used as a paper strength enhancer, can be used to create hydrogen between pulp fibers that have not been subjected to flocculation in flocked valve fibers or high molecular weight ones. It is anticipated that superior burst strength will be provided to promote bonding and form a balanced network of valve fibers. Therefore, the blending ratio of the 2N polyacrylamides used, which have different weight average molecular weights, is an important point when valve fibers form a sheet, and has a large effect on freeness during the papermaking process and the strength of the paper.

Here, the weight average molecular weight of this polyacrylamide is
It is possible to control the polymerization reaction by adjusting the amount of polymerization initiators, polymerization initiation temperature, and polymerization concentration.

Methods for measuring the weight average molecular weight include the gel vermicin chromatography method (hereinafter abbreviated as GPC method), the viscosity method,
Although there are various light scattering methods, the present invention employs the GPC method. Various aqueous gel columns can be used as the GPCO column, and it can be determined from the calibration curve of the column.

The method of Hofmann decomposition reaction will be described below.

When performing the Hofmann decomposition reaction, polyacrylamide as a raw material can be used for the reaction as it is or diluted if necessary when the polyacrylamide is produced in an aqueous solution. In addition, in the case of a graft copolymer, ungrafted polyacrylamide is also produced as a by-product, but it is normally used in the reaction without being separated.

The Hofmann decomposition reaction is carried out by allowing hypohalite to act on the amide group of polyacrylamide in the coexistence of an alkaline substance.
Examples include hypobromous acid and hypoiodic 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 mol, preferably 0.1 to 1.5 mol, based on the amide group for hypohalous acid, and 0.1 to 1.5 mol for the amide group for the alkaline substance. 0.05 to 4.0 mol, preferably 0
．． The amount is 1 to 3.0 moles. The pH at that time is approximately in the range of 11 to 4. The concentration of polyacrylamide at this time is approximately 0.1 to 17.5% by weight, but as the reaction concentration becomes high, stirring becomes difficult and gelation tends to occur, it is usually 0.1 to 10. A range of % by weight is preferred. Further, if the reaction concentration is less than 1x, there are problems such as slow reaction rate, so it is more preferably 1 to 10% by weight.

In addition, when performing the Hoffman decomposition reaction, dimethylaminoethanol, diethylaminoethanol, dimethylamine propatool, choline chloride, benzyl chloride quaternized product of dimethylaminoethanol, polyethylene glycol, polypropylene glycol, etc. have amine groups or hydroxyl groups in their molecules. The reaction may be carried out in the presence of a compound.

The Hofmann decomposition reaction is carried out at a temperature range of -10 to 110'C. The reaction time varies depending on the reaction temperature, and is approximately 24 hours at 0°C, 3 hours at 20°C, 1 minute at 50°C, and about 10 seconds at 80°C. Particularly, when the reaction is carried out in the range of 50 to 110''C, it is preferable to carry out the reaction in this temperature range because a suitable result can be obtained within a short time as shown in the following range.

T: Reaction temperature (°C) 50≦T≦110 The cationic polyacrylamide produced under the above conditions has a cation equivalent value of approximately 0 to 10.0 as measured by colloid titration at pH 2. Omeq/g, and the cation equivalent weight can be controlled by adding the hypohalogen M salt. 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 approximately 0 to lo, Omeq/gc.
) within the range. The amount of by-product can be controlled by the amount of alkaline substance added.

Next, after carrying out the reaction under the above conditions, it is preferable to stop the reaction in order to suppress the progress of side reactions. however,
When used immediately after the reaction, it may not be necessary to stop the reaction.

Methods for stopping the reaction include (1) adding a reducing agent;
Methods such as (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. Examples of the reducing agent used include sodium sulfite, sodium thiosulfate, ethyl malonate, thioglycerol, and triethylamine. The amount of reducing agent used is usually 0.005 to 0 relative to the hypohalous acid used in the reaction.
．． 15 times molar, preferably 0. O1 to 0.10 times the mole. 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 equal to or less than the number of moles of acrylamide units in the polymer, and if 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,
Examples of this method include 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 usually has an alkaline pH of 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. Examples of acids used for pH adjustment include mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, and organic acids such as formic acid, acetic acid, and citric acid. The reaction termination method can be appropriately selected from among (1) to (3) depending on the reaction conditions, and these methods may be combined.

Next, the reaction solution stopped by the above method can be used as it is as an aqueous solution of cationic polyacrylamide, or the aqueous solution can be poured into a solvent such as methanol that does not dissolve cationic polyacrylamide to precipitate the polymer and then dry it. It can also be made into a powder. Moreover, the cationic polyacrylamide aqueous solution can be stored in a tank and used as needed. The temperature at which the aqueous solution is stored may be as low as not freezing, preferably 10 to 15°C. However, if it is to be used within a relatively short period of time, it can be stored at room temperature, and can be stored for about one month.

When the reaction is carried out in the temperature and time range represented by formulas (1) and (2), the above-mentioned stopping operation may be performed, but
It is more desirable to use it immediately after the reaction without performing a stopping operation.

The method of the present invention is used in the process of paper-making valves, and is highly effective in improving freeness to prevent water drainage during paper-making and increasing paper strength by increasing the mechanical strength of paper.

Paper produced by the method described above has excellent paper strength, specifically burst strength, Z-axis strength, compressive strength, and the like. 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, by applying the present invention to papers that require strength, not just corrugated paper and newspaper, it becomes possible to produce paper with excellent paper strength.

The present invention will be explained in detail below using production examples, synthesis examples, examples, and comparative examples.

Incidentally, unless otherwise specified, % and parts are M parts and M parts.

[Production Example 1] 237.5% of 40% acrylamide was placed in a four-way flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas introduction tube.
g, 6.3 g of 80% acrylic acid and 758.2 g of water
and then adjusted to pH 4.5 with 10% caustic soda. After that, nitrogen gas is blown into the internal temperature t.
The temperature was raised to -45°C. While stirring, a 10% aqueous ammonium persulfate solution and a 10% aqueous sodium bisulfite solution were added to initiate polymerization. Heat generation occurred up to 75°C, and then the reaction heat stopped, so the temperature was kept at 75°C and the polymerization reaction was continued for 3 hours after the start of polymerization. When a portion of this product was taken and its molecular weight was measured by GPC, the molecular weight was 30,000. This is called sample A.

[Production Example 2] 237.5 g of 40% acrylamide was placed in a Yotsuro flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas introduction tube.
, 6.3 g of 80% acrylic acid and 756.2 g of water were charged, and then the pH was adjusted to 4.5 with 10% caustic soda. After that, while blowing nitrogen gas, the internal temperature was reduced to 3.
The temperature was raised to 5°C. While stirring, a 10% aqueous ammonium persulfate solution and a 10% aqueous sodium bisulfite solution were added to initiate polymerization. Heat generation occurred up to 73°C, and then the reaction heat stopped, so the temperature was kept at 75°C, and the polymerization reaction was continued for 3 hours after the start of polymerization, and then cooled to room temperature.

When a portion of this product was taken and its molecular weight was measured by GPC, the molecular weight was 390,000.

Further, 970 g of water was placed in an 11-volume beaker, and while stirring, 30.0 g of a weakly anionic acrylamide polymer flocculant (Acofloc A-100 manufactured by Mitsui Cyanamid Co., Ltd.) with a molecular weight of 3117 million was added and dissolved.

Molecule j, which had been produced in advance, is added to the solution on the east side of this polymer a.
33.3 g of 1.39 million polyacrylamide was added,
This solution was sufficiently stirred to obtain a sample as a homogeneous solution. This is called sample B.

[Production Example 3] Polymerization was carried out in the same manner as in Production Example 1 using 213.8 g of 40% acrylamide, 5.63 g of 80% acrylic acid, and 770.6 g of water. The molecular weight of the obtained polymer was determined by GPC to be 420,000. Met. To the thus obtained polyacrylamide, 10.0 g of a weakly anionic acrylamide-based polymer flocculant with a molecular weight of 17 million (Acofloc A-100 manufactured by Mitsui Cyanamid Co., Ltd.) was added, and the solution was sufficiently stirred to form a homogeneous solution. did.

This was designated as sample C.

[Production Example 4 Using 188.25 f of 40% acrylamide, 4.38 f of 80% acrylic acid, and 799.4 g of water,
GP of the polymer obtained as a result of polymerization in the same manner as in Production Example 1
The molecular weight based on C was 150,000. This has molecules 1117
1,000,000 weakly anionic acrylamide polymer flocculant (Acofloc A-100 manufactured by Mitsui Cyanamid Co., Ltd.) 3
0.0g was added, and the solution was sufficiently stirred to form a homogeneous solution. This was designated as sample D.

[Production Example 5] Polymerization was performed in the same manner as in Production Example 1 using 235.4 g of 40% acrylamide, 6.24 g of 80% acrylic acid, and 758.3 g of water. GPC of the obtained polymer
The molecular weight was 400,000. In this, molecule ff117
0.1 g of a weak acrylamide-based polymer flocculant (Acofloc A-100 manufactured by Mitsui Cyanamid Co., Ltd.) was added, and the solution was sufficiently stirred to form a homogeneous solution.

This was designated as sample E.

[Production Example 6] Take 900 g of water in an 11-volume beaker, and while stirring, add 100 g of a weakly anionic acrylamide polymer flocculant (Acofloc A-100, manufactured by Mitsui Cyanamid Co., Ltd.) with a molecular weight of 17 million. Dissolved. This was designated as sample F.

[Synthesis Example 1 Sample A produced in Production Example 1 was reprecipitated using methanol in a 10-fold boiler, and then dried. 10 g of the sample A was dissolved in 140 g of distilled water. The solution was heated to 80°C and a mixture of 17.7 g of 12.5% sodium hypochlorite solution, 7.5 gs of 30% sodium hydroxide solution and 24.8 g of distilled water was added at once under stirring. After 10 seconds, the reaction mixture was poured into an aqueous solution containing excess sodium sulfite to stop the reaction. This is designated as sample S-1.

[Synthesis Example 2] Sample S-2 was obtained by following the method of Synthesis Example 1 except that Sample B produced in Production Example 2 was used.

[Synthesis Example 3] Sample S-3 was obtained by following the method of Synthesis Example 1 except that Sample C produced in Production Example 3 was used.

[Synthesis example 4 Using Sample D manufactured in Production Example 4, 20'C.

All procedures were as in Synthesis Example 1 except that the Hoffmann decomposition reaction was carried out for 2 hours.
Sample S-4 was obtained according to the method.

[Synthesis Example 5] Sample S-5 was obtained by following the method of Synthesis Example 1 except that Sample D produced in Production Example 4 was used.

[Synthesis Example 6] Sample S-6 was obtained by following the method of Synthesis Example 1 except that Sample E produced in Production Example 5 was used.

[Synthesis Example 7] Sample S-7 was obtained by following the method of Synthesis Example 1 except that Sample F produced in Production Example 6 was used.

As mentioned above, samples A-F obtained in Production Examples 1 to 6 and samples S-1 to S-1 of Synthesis Examples 1 to 7 obtained by Hofmann decomposition thereof.
S-7 is summarized in Table-1.

[Example 1] For a 1.0 part concentration slurry of 380 ml of pulp with a freeness obtained from NBKP/LBKP=1/1 (hereinafter referred to as C, S, F), talc was added at a ratio of 10% to the valve. was added and stirred for 2 minutes, then a commercially available rosin emulsion sizing agent was added in an amount of 0.01% based on the pulp on a dry weight basis, and the mixture was stirred for 2 minutes. The pH was then adjusted to 564 by adding 1.0% aluminum sulfate on a dry weight basis,
Sample S obtained in Synthesis Example 3 after further stirring for 1 minute
-3 was added at 0.5% on a dry weight basis, and stirring was continued for an additional 1.
Lasted for minutes.

A portion of this material was taken and its freeness was measured according to JIS P-8121, and at the same time, it was made into Tappi Millumin square sheet machine paper. The paper-made wet sheet is dehydrated using a press and heated to 110°C using a drum dryer.
, 3 minutes of drying was performed to obtain sample S-3-added handmade paper with a weight of 1100 g/r/ft. Furthermore, the specific bursting strength of this paper was measured according to JISP-8112.

[Examples 2 and 3] Paper samples were obtained based on Example 1, except that paper was made using Sample S-4 obtained in Synthesis Example 4 and Sample S-5 obtained in Synthesis Example 5, and the physical properties were The test was conducted.

[Comparative Examples 1 to 4] Sample S-1 obtained in Synthesis Example 1, Sample S-2 obtained in Synthesis Example 2, Sample S-6 obtained in Synthesis Example 6, and Sample S- obtained in Synthesis Example 7 Paper samples were obtained and subjected to physical property tests based on the same procedure as in Example 1, except that the paper was made using Examples 7 to 1.

Table 2 shows the test results of Examples 1 to 3 and Comparative Examples 1 to 4.
summarized in.

[Example 4 C, S, F 1% of recycled corrugated paper beaten to 350 m1
Sulfate band was added to the pulp slurry to adjust the pH to two levels. The pH of 0.5% and 2% of sulfuric acid added to 1% pulp slurry was 6.5, respectively.
．． It was 4.6.

Sample S-3 obtained in Synthesis Example 3 was added in an amount of 0.5% on a dry weight basis to each of the 1% pulp slurries having different pH values, and stirring was continued for 1 minute.

A portion of this material was taken and its freeness was measured according to JISP-8121, and at the same time paper was made using a square sheet machine (Tapl). The paper-made wet sheet was dehydrated using a press and dried at 110°C in a drum dryer for 3
After drying for 1 minute, sample S-
3-added handmade paper was obtained. Furthermore, the Z-axis strength of this paper was measured using an internal bond tester manufactured by Kumagai Rikiko M■.

[Example 6, 6 Paper samples were obtained based on Example 4 except that paper was made using Sample S-4 obtained in Synthesis Example 4 and Sample S-5 obtained in Synthesis Example 5, Physical property tests were conducted.

[Comparative Examples 5 to 8] Sample S-1 obtained in Synthesis Example 1, Sample S-2 obtained in Synthesis Example 2, Sample S-6 obtained in Synthesis Example 6, and Sample S- obtained in Synthesis Example 7. Paper samples were obtained and subjected to physical property tests based on the same procedure as in Example 4, except that paper was made using Example 7.

The test results of Examples 4 to 6 and Comparative Examples 5 to 8 are shown in Table 3.
? Summarize.

[Effects of the Invention] The papermaking additive of the present invention is less susceptible to the effects of inorganic salts and soluble growth substances contained in white water, so it has a remarkable paper strength enhancing effect compared to other papermaking additives. and shows an effect of improving drainage.

The above will be explained according to Tables 2 and 3.

Table 2 shows the physical property results for high-quality paper using NBKP and LBKP as valve raw materials. Looking at the results, it was found that the low-molecular acrylamide of Comparative Example 1 and the high-molecular flocculant content of Comparative Example 2.4 (that is, the high-molecular-weight polyacrylamide content), or Example 1 has an extremely low content of polymer flocculant in Example 3.
．． 2. Compared to No. 3, the papermaking additive of the present invention, both paper strength and freeness are considerably lower.

Both the paper strength and freeness of the paper in which the Hofmann decomposition reaction of Example 2 was carried out at a low temperature for a long time and the Hofmann decomposition reaction of Example 3 which was carried out at a high temperature and a short time are considerably higher than those of the comparative example. This result is almost unaffected by the temperature and time of the Hofmann decomposition reaction. However, when using the Hofmann decomposition reaction apparatus reported by the present inventors, Hofmann decomposition reactants can be easily obtained in a short time, so a high temperature, short time reaction may be advantageous because of better workability. .

Table 3 shows the physical property results when waste paper was used for the raw material valve. Table 3 is similar to Table 2 above, showing that the papermaking additive of the present invention in Example 4゜5.6 exhibits high paper strength and good freeness, almost unaffected by white water constituents. Therefore, it is clear that the papermaking additive and addition method of the present invention are excellent as a paper strength enhancer and drainage improver, and as a method for adding them.

Claims (4)

[Claims] (1) Contains 50 to 99.8% of polyacrylamide with a weight average molecular weight in the range of 50,000 to 500,000, and 0.2 to 50% of polyacrylamide with a weight average molecular weight in the range of 500,000 to 20 million. A papermaking additive obtained by reacting polyacrylamide with hypohalite in an alkaline environment. (2) Contains 50 to 99.8% of polyacrylamide with a weight average molecular weight in the range of 50,000 to 500,000, and 0.2 to 50% of polyacrylamide with a weight average molecular weight in the range of 500,000 to 20 million. A papermaking additive obtained by reacting polyacrylamide with a hypohalite salt in an alkaline temperature range of 50 to 110°C for a short time. (3) A method for increasing paper strength, which comprises adding the papermaking additive according to claim 1 to a pulp slurry immediately after production. (4) A method for improving drainage, which comprises adding the papermaking additive according to claim 2 to the pulp slurry immediately after production.