JPH06199965A - Production of paper strengthening agent - Google Patents

Abstract

PURPOSE:To provide the strengtheningagent less apt to be affected by a change in pH by copolymerizing a specific vinylic monomer, a specific vinylic monomer having a carboxyl group, etc., a specific polyvinylic monomer and (meth) acrylamide each in a specific proportion under specific conditions. CONSTITUTION:Monomers comprising (A) 0.5-20mol.% of a tertiary amino group-having vinylic monomer (salt) and/or its quaternary ammonium salt, (B) 0.520mol.% of a vinylic monomer (salt) having a carboxyl group and/or a sulfonyl group, (C) 0.01-2mol.% of a polyvinylic monomer such as methylene bisacrylaminde, and (D) 55-98.99mol.% of (meth)acrylamide are copolymerzed by a method comprising (i) the components A-D are continuously added dropwise and copoymerized, (ii) the components A, B and C are continuously added dropwise thereto and copolymerized in the presence of the component C, (iii) after the components B and C are copolymerized, the components A and D are continuously added dropwise thereto and copolymerized, or (iv) after the components B and D are copolymerized in the presence of the component C, the components A and D are copolymerized, thus providing the objective paper strengthening agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a paper strengthening agent for paper. More specifically, the copolymer produced by the polymerization method of the present invention has a p-slurry of pulp slurry during papermaking.
A paper that has a small effect variation with respect to changes in H (hereinafter referred to as papermaking pH) and a small decrease in effect with respect to dissolved components present in the pulp slurry, for example, inorganic salts such as sodium sulfate and calcium sulfate. It is intended to provide a method capable of producing a strength enhancer.

[0002]

2. Description of the Related Art Conventionally, an anionic polyacrylamide (hereinafter, polyacrylamide is referred to as PAM) has been mainly used as a paper strengthening agent alone, but white water is closed or neutral due to problems such as drainage regulations. Transition to papermaking,
The purpose is to improve the fixing of the sizing agent associated therewith, further improve drainage and filler retention, and the like, by using anionic PAM and amphoteric (cationic) PAM together, drainage performance, filler and sizing agent fixing performance, and paper The force effect etc. were improved. Recently, anionic PAM and amphoteric (cationic) PA
The simultaneous addition formulation and mixed addition formulation of M have been developed, and further drainage performance, fixing of sizing agent, and paper strength effect can be expected. However, in terms of equipment, two series are required for anion and amphoteric (cation). It is also known that the whiteness, which is regarded as important in the paper field, is greatly reduced. This is anionic PAM and amphoteric (cationic) PA
It is a major factor that the fine fibers and the dust in the white water system, which greatly reduce the whiteness due to the aggregation of M, are retained in the paper. Further, there are cases where deterioration of the texture of paper becomes a problem due to the strength of cohesive force. Recently, vinyl monomers having a tertiary amino group and salts thereof and / or 4
Paper strength agents, which are produced by using cation-based cationic vinyl monomers of quaternary ammonium salts obtained by reaction with a grading agent and acrylamide as a main raw material, have begun to be used considerably. These paper strength enhancers are generally used alone, have a relatively wide effective paper making pH range as a single use, and have paper strength, sizing fixing effect, filler retention effect,
Also, it is possible to obtain features such as a small decrease in whiteness. However, as compared with the conventional combined use of anionic PAM and amphoteric (cationic) PAM, in terms of strength when used alone, there is still no satisfactory result.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a third conventional method.
A paper-strengthening agent produced by using a cationic vinyl-based monomer of a quaternary ammonium salt obtained by a reaction of a vinyl-based monomer having a secondary amino group with a salt thereof and / or a quaternizing agent and acrylamide as a main raw material. Providing a paper-strengthening agent with a high paper-strengthening effect, a small fluctuation in the effect on pH fluctuations, and a small fluctuation in the effect on dissolved components present in pulp slurry by changing the manufacturing method. To do.

[0004]

That is, the present invention provides a vinyl-based monomer having a tertiary amino group, salts thereof, and / or
Or 0.5 to 20 mol% of a quaternary ammonium salt (a) obtained by the reaction with a quaternizing agent, and 0.5 to 20% of a vinyl monomer having a carboxyl group and / or a sulfone group and salts thereof (b). ˜20 mol%, polyvinyl monomer (c) 0.01 to 2 mol%, (meth) acrylamide (d) 55 to 99.99 mol
% Of the constituent monomer components are polymerized by the following method. [1] A method for producing a paper-strengthening agent characterized by polymerization by continuously dropping (a), (b), (c), and (d). Polymerization by continuously dropping (a) (b) (d) in the presence of [2] (c), [3] (b) (c) (d), and then (a) (d)
Polymerization by continuously dropping [4] (c), polymerization by continuously dropping (b) (d), and then polymerization by continuously dropping (a) (d).

In the present invention, which will be described in detail below, the quaternary ammonium salts obtained by the reaction of a vinyl monomer having a tertiary amino group with a quaternizing agent are, for example, dimethylaminopropyl. (Meth) acrylate, dimethylaminoethyl (meth) acrylate,
Examples include dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide.
Examples of the quaternizing agent in the present invention include chloromethane, benzyl chloride, p-chlorobenzyl chloride, p-methylbenzyl chloride, p-nitrobenzyl chloride and the like. A vinyl-based monomer having a quaternary ammonium salt can be provided by reacting the vinyl-based monomer having a tertiary amino group with a quaternizing agent. The amount of these monomers used is usually 0.5 to 20 mo.
It is 1%, preferably 1 to 10 mol%. 0.
If it is less than 5 mol%, the polymer is difficult to be fixed to the pulp fiber and the paper strength effect cannot be sufficiently exhibited, and if it exceeds 20 mol%, it is economically disadvantageous. The vinyl monomer having a carboxyl group used in the present invention and salts thereof are maleic acid,
Examples thereof include fumaric acid, itaconic acid, (meth) acrylic acid, crotonic acid, unsaturated carboxylic acids such as citraconic acid, and salts thereof. The vinyl monomer having a sulfo group and salts thereof include vinyl sulfonic acid, styrene sulfonic acid, (meth) allyl sulfonic acid,
2-acrylamido-2-methylpropanesulfonic acid,
Examples thereof include unsaturated sulfonic acids such as 2-acrylamido-2-phenylpropanesulfonic acid and salts thereof. The amount of these monomers used is usually 0.5 to
It is 20 mol%, preferably 1 to 10 mol%. If it is less than 0.5 mol%, there is a problem in fixing the paper-strengthening agent to the pulp, and if it exceeds 20 mol%, the balance between the amount of cation and anion in the paper-strength agent becomes a problem, and the paper-strengthening effect is sufficient. There is an inconvenience that it cannot be expressed in.

The polyvinyl-based monomer of the present invention may be a monomer having at least two double bonds in the molecule. Specifically, methylene bis acrylamide, diallyl acrylamide, triacryl formal, diacryloyl imide, ethylene glycol acrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimeth Methacrylate, glycerol dimethacrylate neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, divinylbenzene, diallyl phthalate and the like can be used. The amount of these used varies depending on the type of the polyvinyl-based monomer and cannot be generally stated, but it is usually 0.01 to 2 mol%, preferably 0.01 to 1 mol%. 0.01 mol%
If it is less than 2, there is a disadvantage that the paper strength effect cannot be sufficiently exhibited, and if it exceeds 2 mol%, there is a disadvantage that gelation occurs. The (meth) acrylamide used in the present invention is sufficient if it is commercially available in the form of powder or an aqueous solution and is industrially used.

Further, the polymerization initiator is not particularly limited as long as it is a water-soluble substance, and it is usually used by dissolving it in an aqueous monomer solution. Specifically, hydrogen peroxide, peroxides such as benzoyl peroxide, sodium persulfate, potassium persulfate,
Persulfates such as ammonium persulfate, sodium bromate, bromates such as potassium bromate, sodium perborate, potassium perborate, perborates such as ammonium perborate, sodium percarbonate, potassium percarbonate,
Examples thereof include percarbonates such as ammonium percarbonate, sodium perphosphate, potassium perphosphate, and perphosphates such as ammonium perphosphate. 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. Examples of the reducing agent include sulfites, bisulfites, low-order ionized salts such as iron, copper and cobalt, N, N,
Examples thereof include organic amines such as N ′, N′-tetramethylethylenediamine, and reducing sugars such as adose and ketose. Also, as the azo compound, 2,2 '
-Azobis-4-amidinopropane hydrochloride, 2,2'-
Azobis-2,4-dimethylvaleronitrile, 4,4 '
-Azobis-4-cyanovaleic acid and its salt can be used. Furthermore, it is also possible to use two or more of the above-mentioned polymerization initiators in combination. The polymerization temperature is about 30-
It is 90 ° C., and it is preferable to suppress the heat generation due to the polymerization and reduce the temperature change. The atmosphere in the polymerization vessel is not particularly limited, but it is better to replace it with an inert gas such as nitrogen gas in order to carry out the polymerization rapidly. The continuous dropping time of the monomer is not particularly limited, but is generally 40 to 180.
The time is preferably 40 to 120 minutes. The polymerization time is generally 2 to 20 hours, preferably 2 to 4 hours.

The paper-strengthening agent produced by the method of the present invention is used in the process of making pulp, and improves drainage for improving drainage during papermaking and enhances mechanical strength of paper. Bring great effect to. At this time, the paper strengthening agent produced by the method of the present invention can be used alone, but may be used in combination with a sulfuric acid band, anionic polyacrylamide, Mannich modified polyacrylamide, Hoffmann modified polyacrylamide, or the like. The addition amount of the paper strengthening agent of the present invention varies depending on the type of pulp, the speed of papermaking, etc. and cannot be generally stated, but it is respectively 0.01 to 3%, preferably 0.03% to the dry solid weight of the pulp. It is in the range of 05 to 1%. The addition place may be anywhere before the wet sheet is formed, and usually, it is added between the refiner outlet and the inlet. The paper produced by the above method exhibits a paper strength effect in a wide pH range in a papermaking system in which a large amount of salts are present, and is specifically excellent in burst strength, compression strength, Z-axis strength and the like. Therefore, by applying the present invention, it becomes possible to manufacture a paper having excellent paper strength. The reason for this is unclear, but when polymerized with a small amount of a polyvinyl monomer such as divinyl monomer or trivinyl monomer, a partially crosslinked polymer is formed, and the monomer is continuously supplied to this. Upon polymerization, this cross-linked polymer will be easier to polymerize. Therefore, due to the high molecular weight and the polymer's particle-like movement, the pH of the pulp slurry when the strength agent is fixed to the pulp is
It is thought that it is less likely to be affected by or ionic strength.

[0009]

EXAMPLES Next, the present invention will be specifically described by way of examples by dividing it into production examples and application examples, but the present invention is not necessarily limited to the following examples. The weight average molecular weight is the GPC method (Shodex GPC System).
em-11, using column KB-80M).
It is a value converted to polyethylene glycol in a 1N-NaNO ₃ aqueous solution: formamide = 3: 7 mixed solution. Example 1 40% acrylamide 312.7 in a Griffin beaker
2 g (91.94 mol%), 80% N-methacryloyloxyethyl trimethyl ammonium chloride 19.
86g (4mol%), 80% acrylic acid 1.72g
(1 mol%), itaconic acid 7.47 g (3 mol%)
Methylenebisacrylamide 177mg (0.06mo)
1%), adjust the pH to 4.5 with 28% ammonium hydroxide,
(A) A solution was prepared. 558.06 g of water in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube.
Was charged and the pH was adjusted to 4.5 with 2.5% sulfuric acid. Then, while blowing nitrogen gas, the mixture was stirred and the inner temperature was raised to 50 ° C. in a water bath. (A) 50 g of ammonium persulfate aqueous solution at the same time when continuous dropping of the solution is started
Then, 50 g of an aqueous sodium hydrogen sulfite solution was continuously added dropwise to initiate polymerization, and the solution (A) was added dropwise over 70 minutes.
When the reaction was carried out at a constant temperature of 50 ° C for 3 hours, the nonvolatile content was 15.
7%, Brookfield viscosity at 25 ° C 9.2
An amphoteric polymer aqueous solution having a pH of 90 cps, a weight average molecular weight of 800,000 and an isoelectric point at turbidity of pH 4.8 was obtained.

Example 2 40% acrylamide 312.7 in a Griffin beaker
2 g (91.94 mol%), 80% N-methacryloyloxyethyl trimethyl ammonium chloride 19.
86g (4mol%), 80% acrylic acid 1.72g
(1 mol%), itaconic acid 7.47 g (3 mol%)
Was charged and the pH was adjusted to 4.5 with 28% ammonium hydroxide to obtain a solution (A). In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, 177 mg (0.06 mol%) of methylenebisacrylamide and 558.0 water.
6 g was charged, and the pH was adjusted to 4.5 with 2.5% sulfuric acid.
Other than that, the same operation as in Example 1 was conducted to obtain a nonvolatile content of 15.5%,
Brookfield viscosity at 25 ° C 8,150 cp
Thus, an amphoteric polymer aqueous solution having a pH of 4.0, a weight average molecular weight of 1,000,000, and an isoelectric point at turbidity of pH 4.8 was obtained. Example 3 40% acrylamide 293.17 in a Griffin beaker
g (86.19 mol%), 80% N-methacryloyloxyethyl trimethyl ammonium chloride 19.
Charge 86g (4mol%), pH with 2.5% sulfuric acid
The solution was adjusted to 4.5 to give a solution (A). 19.55 g of 40% acrylamide (5.75 mol) in a 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube.
%), 80% acrylic acid 1.72 g (1 mol%), itaconic acid 7.47 g (3 mol%), methylenebisacrylamide 177 mg (0.06 mol%) and water 55.
8.06 g was charged, and after dissolution, the pH was adjusted to 4.5 with 28% ammonium hydroxide. Otherwise by performing the same operations as in Example 1, non-volatile content 15.7%, Brookfield viscosity at 25 ° C. 8,730 cps, pH 4.7, weight average molecular weight 130.
An amphoteric polymer aqueous solution having an isoelectric point of 5.5 at turbidity was obtained.

EXAMPLE 4 40% acrylamide 19.55 in a Griffin beaker
g (5.75 mol%), 80% acrylic acid 1.72 g
(1 mol%), itaconic acid 7.47 g (3 mol%) and water 58.63 g were charged, and after dissolution, pH was adjusted to 28% ammonium hydroxide.
The solution was adjusted to 4.5 to give a solution (A). In addition, 293.17 g of 40% acrylamide (86.
19 mol%), 80% N-methacryloyloxyethyl trimethyl ammonium chloride 19.86 g
(4 mol%) was charged and the pH was adjusted to 4.5 with 2.5% sulfuric acid to prepare a (B) solution. A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 177 mg (0.06 mol%) of methylenebisacrylamide and 499.43 g of water, and pH was adjusted to 4.5 with 2.5% sulfuric acid. Adjusted to. Then, while blowing nitrogen gas, the mixture was stirred and the inner temperature was raised to 50 ° C. in a water bath.
At the same time when the continuous dropping of the solution (A) was started, 50 g of an aqueous ammonium persulfate solution and 50 g of an aqueous sodium hydrogen sulfite solution were continuously dropped to start polymerization. (A) Solution 1
The solution was added dropwise over 4 minutes, and after 10 minutes, the solution (B) was added dropwise over 56 minutes. When the reaction was carried out at 50 ° C. for 3 hours, the nonvolatile content was 15.7%, the Brookfield viscosity at 25 ° C. was 9,600 cps, the pH was 4.7, the weight average molecular weight was 1.3 million, and the isoelectric point at turbidity was pH 5.5. An amphoteric polymer aqueous solution was obtained.

Comparative Example 1 312.72 g of 40% acrylamide was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube.
(91.94 mol%), 80% N-methacryloyloxyethyl trimethyl ammonium chloride 19.8
6 g (4 mol%), 80% acrylic acid 1.72 g (1
mol%), itaconic acid 7.47 g (3 mol%), methylenebisacrylamide 177 mg (0.06 mol)
%) And 625.79 g of water, and then adjusted to pH 4.2 with 20% caustic soda. Thereafter, while blowing nitrogen gas, the internal temperature was raised to 50 ° C. and then covered with a heat insulating material. While stirring, 10% ammonium persulfate aqueous solution and 10% sodium hydrogen sulfite aqueous solution were added to initiate polymerization. 10 minutes after reaching the reaction peak, water was added to complete the polymerization reaction.
%, Brookfield viscosity at 25 ° C 7,850
An amphoteric polymer aqueous solution having a cps, a pH of 4.3, a weight average molecular weight of 500,000 and an isoelectric point of 4.8 in turbidity was obtained. Example 5 40% acrylamide 320 in a Griffin beaker.
99 g (91.94 mol%), dimethylaminoethyl methacrylate 12.34 g (4 mol%), 80% acrylic acid 1.77 g (1 mol%), itaconic acid 7.67
g (3 mol%) methylenebisacrylamide 182 mg
(0.06 mol%) was charged and the pH was adjusted to 4 with 20% sulfuric acid.
The solution was adjusted to 5 to give a solution (A). Stirrer, reflux condenser,
Water in a four-necked flask equipped with a thermometer and a nitrogen gas inlet tube.
39.06 g was charged and the pH was adjusted to 4.5 with 2.5% sulfuric acid. Otherwise, the same operation as in Example 1 was performed to
5.6%, Brookfield viscosity at 25 ° C 8,
An amphoteric polymer aqueous solution having a pH of 4.1 at 430 cps, a weight average molecular weight of 700,000 and an isoelectric point at turbidity of 4.3 was obtained.

Example 6 40% acrylamide 3209 in a Griffin beaker
9 g (91.94 mol%), dimethylaminoethyl methacrylate 12.34 g (4 mol%), 80% acrylic acid 1.77 g (1 mol%), itaconic acid 7.67 g
(3 mol%) was charged and the pH was adjusted to 4.5 with 20% sulfuric acid to prepare a (A) solution. A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 182 mg (0.06 mol%) of methylenebisacrylamide and 539.06 g of water, and pH was adjusted to 4.5 with 2.5% sulfuric acid.
Adjusted to 5. Other than that, the same operation as in Example 1 was carried out to obtain a nonvolatile content of 15.5%, Brookfield viscosity at 25 ° C. of 10, 260 cps, pH 4.1, and weight average molecular weight of 10.
An amphoteric polymer aqueous solution having an isoelectric point of 4.3 at a turbidity of 0,000 was obtained. Example 7 40% acrylamide 300.9 in a Griffin beaker
Charged 3 g (86.19 mol%) and dimethylaminoethyl methacrylate 12.34 g (4 mol%), 20%
The pH was adjusted to 4.5 with sulfuric acid to obtain a solution (A). 20.06 g (5.0%) of 40% acrylamide in a 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube.
75 mol%), 80% acrylic acid 1.77 g (1 mo
1%), itaconic acid 7.67 g (3 mol%), methylenebisacrylamide 182 mg (0.06 mol%),
Charge 539.06 g of water, dissolve and dissolve in 28% ammonium hydroxide to pH
Adjusted to 4.5. Others perform the same operation as in Example 1,
Thus, an amphoteric polymer aqueous solution having a nonvolatile content of 15.6%, a Brookfield viscosity at 25 ° C. of 8,440 cps, a pH of 4.7, a weight average molecular weight of 1.2 million, and an isoelectric point of 5.5 at turbidity was obtained.

Example 8 40% acrylamide 20.06 in a Griffin beaker
g (5.75 mol%), 80% acrylic acid 1.77 g
(1 mol%), itaconic acid 7.67 g (3 mol%) and water 60.18 g were charged, and after dissolution, pH was adjusted to 28% ammonium hydroxide.
The solution was adjusted to 4.5 to give a solution (A). In addition, 300.93 g of 40% acrylamide (86.
19 mol%) and 12.34 g (4 mol%) of dimethylaminoethyl methacrylate were added, and the pH was adjusted to 4.5 with 20% sulfuric acid to obtain a solution (B). mixer,
A four-necked flask equipped with a reflux condenser, a thermometer, and a nitrogen gas inlet tube was provided with 182 mg (0.0) of methylenebisacrylamide.
6 mol%) and 477.88 g of water were charged, and the pH was adjusted to 4.5 with 2.5% sulfuric acid. Otherwise, the same operations as in Example 4 were carried out, with a non-volatile content of 15.6%, a Brookfield viscosity at 25 ° C of 7,320 cps, a pH of 4.8, a weight average molecular weight of 1.3 million and an isoelectric point of 5.8 at turbidity. An amphoteric polymer aqueous solution was obtained.

Comparative Example 2 320.99 g of 40% acrylamide in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube.
(91.94 mol%), dimethylaminoethyl methacrylate 12.34 g (4 mol%), 80% acrylic acid 1.77 g (1 mol%), itaconic acid 7.67 g
(3 mol%), methylenebisacrylamide 182 mg
(0.06 mol%) and 606.80 g of water were charged, and then the pH was adjusted to 4.2 with 20% sulfuric acid. Otherwise, the same operations as in Comparative Example 1 were carried out, and the nonvolatile content was 15.6%, 2
Brookfield viscosity at 5 ° C 6,970 cp
An amphoteric polymer aqueous solution having a pH of 4.3 was obtained. Application Examples 1 to 8 and Comparative Application Examples 1 and 2 Aluminum sulfate was used on a dry weight basis in a pulp slurry having a beating degree (Canadian Standard Freeness, CSF) of 400 ml and a concentration of 1.0% obtained from waste corrugated paper. 0.5 to 1.0% of pulp was added and stirred for 1 minute. The pH of the pulp slurry at this time was 6.1 and 5.0, respectively. Then, the amphoteric polymers obtained in Examples 1 to 4 and Comparative Example 1 were treated with a dry weight of 0.
25% was added and stirring was continued for another minute. Thereafter, the pulp slurry obtained was used to make paper using a TAPPI square sheet machine. The wet sheet made from paper is dried with a drum dryer at 110 ° C. for 3 minutes, and the basis weight is 150 g /
It was obtained m ² of hand-made paper. JIS-P-81 using the above handmade paper
"Specific burst strength" according to No. 12, "Specific compressive strength" according to JIS-P-8126, and "Z-axis strength" with an internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd. The results are shown in.

Application Examples 9 to 16 and Comparative Application Examples 3 to 4 Aluminum sulphate based on the dry weight of the pulp slurries used in Application Examples 1 to 8 and Comparative Application Examples 1 and 2 to the pulp of 0.5 and 1, respectively. 0.0% was added and stirred for 1 minute. Next, 0.5% of the amphoteric polymer obtained in Examples 1 to 4 and Comparative Example 1 was added on a dry weight basis, and applied under exactly the same conditions and operations as in Application Examples 1 to 8 and Comparative Application Examples 1 and 2. The physical properties of Examples 9 to 16 and Comparative Application Examples 3 to 4 were measured and calculated, and the results are shown in Table 2. Application Examples 17 to 24 and Comparative Application Examples 5 to 6 Na ₂ SO ₄ with respect to the pulp slurry used in the above Application Examples 1 to 8 and Comparative Application Examples 1 to 5 was 5 to the pulp.
10% was added, 200 ppm of CaSO ₄ was added to the pulp, and the mixture was stirred for 2 minutes. The electric conductivity of the pulp slurry was changed from 0.15 mS / cm to 0.8 mS / cm and 1.3 ms / cm by adding Na ₂ SO ₄ . Aluminum sulfate was added thereto in an amount of 1.0% based on the dry weight, and the mixture was stirred for 1 minute. Then, the amphoteric polymers obtained in Examples 1 to 4 and Comparative Example 1 were added at 0.25% on a dry weight basis,
The physical properties of Application Examples 17 to 24 and Comparative Application Examples 5 to 6 were measured and calculated under exactly the same conditions and operations as those of Application Examples 1 to 8 and Comparative Application Examples 1 and 2, and the results are shown in Table 3.

Application Examples 25-32 and Comparative Application Examples 7-8 For the pulp slurries used in the above-mentioned Application Examples 1-8 and Comparative Application Examples 1-2, Na ₂ SO ₄ was added to pulp 5 times,
10% was added, 200 ppm of CaSO ₄ was added to the pulp, and the mixture was stirred for 2 minutes. Aluminum sulfate was added thereto in an amount of 1.0% based on the dry weight, and the mixture was stirred for 1 minute. Next, 0.5% of the amphoteric polymer obtained in Examples 1 to 4 and Comparative Example 1 was added on a dry weight basis, and applied under exactly the same conditions and operations as in Application Examples 1 to 8 and Comparative Application Examples 1 and 2. Example 2
5 to 32 and comparative application examples 7 to 8 were measured and calculated.
The results are shown in. Application Examples 33 to 40 and Comparative Application Examples 9 to 10 Aluminum sulfate based on the dry weight of the pulp slurries used in Application Examples 1 to 8 and Comparative Application Examples 1 to 2 is 0.5% to pulp. Add and stir for 1 minute. Then, the amphoteric polymers obtained in Examples 5 to 8 and Comparative Example 2 were added in an amount of 0.25% on the basis of dry weight.
Also, the physical properties of Application Examples 33 to 40 and Comparative Application Examples 9 to 10 were measured and calculated under exactly the same conditions and the same operations as Comparative Application Examples 1 and 2, and the results are shown in Table 5. Application Examples 41 to 48 and Comparative Application Examples 11 to 12 Aluminum sulfate based on the dry weight of the pulp slurries used in the Application Examples 1 to 8 and Comparative Application Examples 1 to 2 was 0.5 to 1.0% of the pulp. Add and stir for 1 minute. Next, 0.5% of the amphoteric polymer obtained in Examples 5-8 and Comparative Example 2 was added on a dry weight basis, and applied under exactly the same conditions and the same operations as in Application Examples 1-8 and Comparative Application Examples 1-2. The physical properties of Examples 41 to 48 and Comparative Application Examples 11 to 12 were measured and calculated, and the results are shown in Table 6.

Application Examples 49 to 56 and Comparative Application Examples 13 to 1
4 Na ₂ SO ₄ with respect to the pulp slurries used in the above-mentioned Application Examples 1 to 8 and Comparative Application Examples 1 to 5 was 5:
10% was added, 200 ppm of CaSO ₄ was added to the pulp, and the mixture was stirred for 2 minutes. Aluminum sulfate was added thereto in an amount of 1.0% based on the dry weight, and the mixture was stirred for 1 minute. Next, 0.25% of the amphoteric polymer obtained in Examples 5-8 and Comparative Example 2 was added on a dry weight basis, and applied under exactly the same conditions and operations as in Application Examples 1-8 and Comparative Application Examples 1-2. The physical properties of Examples 49 to 56 and Comparative Application Examples 13 to 14 were measured and calculated, and the results are shown in Table 7. Application Examples 57 to 64 and Comparative Application Examples 15 to 16 Na ₂ SO ₄ is added to the pulp slurry used in Application Examples 1 to 8 and Comparative Application Examples 1 to 5 in a ratio of 5 to pulp.
10% was added, 200 ppm of CaSO ₄ was added to the pulp, and the mixture was stirred for 2 minutes. Aluminum sulfate was added thereto in an amount of 1.0% based on the dry weight, and the mixture was stirred for 1 minute. Next, 0.5% of the amphoteric polymer obtained in Examples 5-8 and Comparative Example 2 was added on a dry weight basis, and applied under exactly the same conditions and the same operations as in Application Examples 1-8 and Comparative Application Examples 1-2. Example 5
The physical properties of 7 to 64 and Comparative Application Examples 15 to 16 were measured and calculated, and the results are shown in Table 8.

[0019]

As shown in Tables 1 to 8, the amphoteric polymer produced under the conditions within the scope of the claims of the present invention has the action of improving the paper strength as shown by the specific burst strength, the specific compressive strength and the Z-axis strength, as compared with the conventional amphoteric polymer. Etc., and is not easily affected by pH fluctuation.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

[Table 5]

[0025]

[Table 6]

[0026]

[Table 7]

[0027]

[Table 8]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeharu Minoda 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. A quaternary ammonium salt (a) obtained by reacting a vinyl monomer having a tertiary amino group with a salt thereof and / or a quaternizing agent is 0.5 to 20.
Vinyl type monomer having mol%, carboxyl group and / or sulfone group and salts thereof (b) are 0.5-2.
0 mol%, polyvinyl-based monomer (c) is 0.01
~ 2mol%, (meth) acrylamide (d) 55
~ 98.9 mol% of the constituent monomers are
A method for producing a paper strengthening agent, which comprises polymerizing by the method of 4 to 4. [1] (a), (b), (c) and (d) are continuously added dropwise for polymerization, and [2] (c) is added and (a), (b) and (d) are added continuously for polymerization. 3] After polymerizing (b) (c) (d), (a) (d)
Polymerization by continuously dropping [4] (c), polymerization by continuously dropping (b) (d), and then polymerization by continuously dropping (a) (d). 2. The method according to claim 1, wherein the total time for continuously dropping the monomer is 40 to 120 minutes. 3. When (d) is divided into first-half polymerization and second-half polymerization, the molar ratio of the first-half: second-half division is 1:23 to 1: 1.
[3] in claim 1 characterized in that
And the method described in [4].