JPS6312792A - Parermaking filter water agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a novel water filtering agent for papermaking.

BACKGROUND OF THE INVENTION Background of the Invention Papermaking water filtering agents, along with sizing agents and paper strength agents, have been praised as internal additives for papermaking that are essential in the papermaking industry. The filtering agent is particularly effective in accelerating water drainage during pulp papermaking and reducing the thermal energy required for drying, so its use can greatly improve paper production efficiency.

Conventionally, as water filtering agents for papermaking, anionic polyacrylamide or cationic polyacrylamide is commonly used alone or in combination by adding both separately. In addition, polyacrylamide used as the water filtering agent has a variety of molecular weights, ranging from high molecular weight products with a weight average molecular weight of about 1000 yen to low molecular weight products with a weight average molecular weight of about several hundred thousand. It is known to exhibit very good drainage effects.

However, these polyacrylamide drainage agents have drawbacks. That is, a high molecular weight type aqueous solution has an extremely high viscosity, resulting in poor workability. In addition, high-molecular-weight powder types require a dissolution process, and they tend to become lumpy, so if used as is, they will not be able to fully demonstrate their performance, and will also cause problems such as stains on paper-making wire and dryer blankets. It will be a hiccup. For this reason, there is a drawback that it takes a long time for complete dissolution, and workability is greatly reduced. On the other hand, low molecular weight types have no problems in terms of workability, but
The drawback is that the drainage effect is inferior to that of high molecular weight types. Thus, conventionally, a water filtering agent for paper making that can satisfy both workability and drainage properties has not yet been obtained.

Means for Solving the Problems The inventors of the present invention aimed to develop a papermaking filtering agent that overcomes the drawbacks of the conventional papermaking filtering agents, has good workability, and has good drainage properties. As a result of intensive studies on the combination of low molecular weight anionic polyacrylamide and cationic polyacrylamide, their combinations, mixing methods, etc., it was surprisingly possible to mix anionic polyacrylamide and a specific cationic polymer in advance. It was discovered that all of the above objects could be achieved for the first time by using an aqueous mixture formed by the following methods. That is, although conventional water filtering agents that used anionic polyacrylamide or cationic polyacrylamide alone or in combination could not solve the above problems, A filtering agent made of an aqueous mixture of anionic polyacrylamide and a relatively low molecular weight cationic Mannich-modified polyacrylamide made of a specific cationic polymer has a remarkable effect on improving drainage without reducing workability. He discovered the scales by expressing this. The present invention has been completed based on this fact.

That is, the present invention provides a papermaking water filtering agent comprising an aqueous mixture of an anionic polyacrylamide having a weight average molecular weight of 100,000 to 2 million and a cationic Mannich-modified polyacrylamide having a weight average molecular weight ff of 1,100,000 to 2,000,000. Pertains to.

The anionic polyacrylamide used in the present invention includes at least one of monomers having a carboxyl group such as acrylic acid and methacrylic acid, and monomers having a sulfonic group such as styrene sulfonic acid and vinylsulfonic acid. Examples include copolymers made of the 7-ionic monomer and acrylamide, and various copolymers obtained by copolymerizing the copolymer with neutral monomers such as acrylonitrile, methacrylamide, and methyl methacrylate. Polymers may also be exemplified. Furthermore, these copolymers may contain a small amount of cationic groups as long as the overall charge properties are anionic. Among these, particularly preferred are acrylic acid-acrylamide copolymer and acrylic acid-acrylonitrile-acrylamide copolymer. Here, the content of the anionic monomer and acrylamide in these copolymers can be selected from a wide range, but
Usually, the former is about 0.5 to 30 mol%, and the latter is about 40 to 99.5 mol%.

If the content of anionic monomer is outside this range,
Since the obtained copolymer itself has insufficient freeness, even if an aqueous mixture with Mannich-modified polyacrylamide, which will be described later, is prepared, the effect of improving freeness, which is the main objective of the present invention, tends not to be significantly exhibited, which is not preferable. . On the other hand, when the content of acrylamide is less than 40 mol%, the freeness of the copolymer itself is insufficient, and the effect of improving freeness tends to be insufficient as described above, and when it exceeds 99.5 mol%, anionic Since it is difficult to exhibit the performance as a polyester copolymer, the effect of improving freeness tends to be insufficient in this case as well, which is not preferable.

The above-mentioned anionic polyacrylamide is usually used in the form of an aqueous solution, but it can be neutralized by adding sodium hydroxide, potassium hydroxide, etc. before or after polymerization to adjust the pH to a slightly acidic level. is preferable. Thereby, it is possible to prevent the aqueous solution from becoming cloudy and from corroding the transportation container and the storage container due to being in a strongly acidic region.

Further, in the present invention, as the anionic polyacrylamide, one having a weight average molecular weight of 100,000 to 2,000,000 is used. If the molecular weight is less than 100,000, the freeness is insufficient, and when the aqueous mixture of the present invention is used, although the effect of improving the freeness is recognized, it is still insufficient. On the other hand, if the molecular weight exceeds 2 million, the workability will be poor.

The cationic Mannich-modified polyacrylamide used in the present invention includes various products produced by so-called Mannich modification of polyacrylamide with formalin and a secondary amine. The polyacrylamide that is the starting material here is not limited to acrylamide alone as a monomer component, but may also contain neutral monomers such as acrylonitrile and methacrylic acid methyl ester. As long as the modified copolymer has a cationic charge property, it may contain a small amount of anionic monomer such as acrylic acid or methacrylic acid. In addition, the cationic Mannich-modified polyacrylamide in the present invention includes one containing about 0.5 to 60 mol% of cationic monomer units based on Mannich modification and about 40 to 99.5 mol% of acrylamide units. A preferred example can be given. If the content of the cationic monomer based on Mannich modification is less than 0.5 mol%, the effect of improving freeness in the aqueous mixture of the present invention will not be sufficient;
Moreover, when it exceeds 60 mol%, formalin and secondary amine used during Mannich modification must be used in excessive amounts, which tends to increase production costs and reduce workability during production. I don't like it. Incidentally, during Mannich modification, a very small portion of the carbamoyl groups may be changed to carboxyl groups, but this does not cause any problem as long as the charged property of the modified polymer is cationic.

Further, in the present invention, the cationic Mannich-modified polyacrylamide has a weight average molecular weight of 10
Use between 10,000 and 2,000,000.

If the molecular weight is less than 100,000, the effect of improving freeness in the aqueous mixture of the present invention will not be sufficient, and if it exceeds 2,000,000, the workability will be reduced.

As a method for Mannich modification of polyacrylamide, a conventional method may be used. For example, raw material polyacrylamide is mixed with formalin and secondary alcohol in an aqueous medium such as water.
Mannich modification can be carried out by adding a class amine and reacting with stirring at about 35 to 80°C for usually about 0.2 to 10 hours, preferably about 0.5 to 2 hours. Through the above reaction, polyacrylamide and formalin undergo a methylolation reaction, and then the generated N-methylolated polyacrylamide and secondary amine react to obtain aminomethylated polyacrylamide, which is necessary for cationic Mannich-modified polyacrylamide. It will be done.

The paper-making drainage agent of the present invention essentially consists of an aqueous mixture of anionic polyacrylamide and cationic Mannich-modified polyacrylamide. That is, only by using these as an aqueous mixture in advance can the freeness be significantly improved without any reduction in workability.

Such effects cannot be obtained when only one of these is used or when both are added separately to the pulp slurry. Although the reason for this is not clear, it is presumed that some kind of interaction occurs between the two by forming the aqueous mixture in advance.

The papermaking drainage agent of the present invention can be prepared, for example, by preliminarily mixing and stirring an aqueous solution of anionic polyacrylamide and an aqueous solution of cationic Mannich-modified polyacrylamide to form an aqueous mixture. If necessary, it may be further diluted with water, alcohol, etc. As these aqueous solutions, aqueous solutions obtained by producing these polymers can be used as they are or after being diluted with water or the like as appropriate. Therefore, the concentration of the aqueous mixture of the present invention is not particularly limited, and may contain a small amount of a water-soluble solvent such as alcohol.

The mixing ratio of the anionic polyacrylamide and the cationic mannitol-modified polyacrylamide in the aqueous mixture of the papermaking filter agent of the present invention can be selected from a wide range, but the solid content weight ratio is usually the former: the latter - 95:5~5:9
It is best to set it to about 5. When either the anionic polyacrylamide or the cationic erectine-modified polyacrylamide is used in an amount exceeding this ratio, the effect of improving freeness by the mixed treatment of the present invention is not sufficient, so it is not preferable. The preferred mixing ratio is the former:latter=90:10 to 30:70.

In the present invention, the cationic polyacrylamide that can be used is limited to the Mannich-modified polyacrylamide specified above. By the way, in addition to the Mannich-modified polyacrylamide used in the present invention, conventional water thinning agents for papermaking include Hoffmann rearrangement products of polyacrylamide, epichlorohydrin-modified products of polyamide polyamine resin, dimethylaminoethyl methacrylate, and dimethylaminopropylacrylamide monomers. Acrylamide-based copolymers containing polymers are known. However, when an aqueous mixture of these is produced using the cationic polymer other than Mannich-modified polyacrylamide and the anionic polyacrylamide, the freeness is significantly improved compared to the aqueous mixture of the present invention. I can't do that, so I'm sorry. The reason for this result is not yet clear, but it is generally observed that aqueous mixtures other than those of the present invention produce gel-like substances and precipitates, and it is assumed that this is because the dispersion and fixing properties in the pulp slurry are reduced. be done. On the other hand, the aqueous mixture of the present invention does not exhibit any such phenomenon and is considered to have good dispersibility.

The papermaking water filtration agent of the present invention can be used in the same manner as a normal water filtration agent. The preferred addition time is after the sulfuric acid hand is added to the pulp slurry, and it is preferable to add it at a location near a part of the papermaking wire. This is because it is desirable to immediately make paper without adding unnecessary shares to the generated flocs. In addition, the amount used may be the same as that of a normal filtering agent, for example, the solid content = l ratio is about 0.005 to 3% by weight of the pulp, preferably 0.01 to 3% by weight.
The content is preferably about 1% by weight.

The aqueous mixture that is the drainage agent of the present invention may be distributed as is. Alternatively, the two may be mixed and used as an aqueous mixture immediately before the papermaking process.

Effects of the Invention According to the novel drainage agent of the present invention, since it is composed of an aqueous mixture of an anionic polyacrylamide with a specific molecular weight and Mannich-modified polyacrylamide, which is a specific cationic polyacrylamide, it can be used without any reduction in workability. , a particularly remarkable effect of significantly improving freeness was observed. Further, in conjunction with this, an advantage can be obtained in that the amount of filtering agent used can be significantly reduced compared to conventional methods.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to production examples and examples, but the present invention is not limited to these examples. It should be noted that all parts and percentages herein are based on weight unless otherwise specified.

Moreover, the molecular weight of each polymer in each production example was measured by the following method.

Measurement of O molecular weight: Using Toyo Soda (manufactured by Taiyo, liquid chromatography measuring device rCCP-8000) and the company's rTSK-GELPWXQj as a column, the mobile phase was acetic acid-sodium acetate buffer (0.5 mol/Q-0.5 It was measured as mol/Q>.The measured value is a polyethylene oxide (standard substance) converted value.

Production Example 1 In a 1000 m 12 four-way flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, 50% acrylamide 2567.80% acryl V, 183, water 4407
Weigh out 47% of isopropyl alcohol and 48%
The pH was adjusted to 5 to 5.5 with caustic soda, and oxygen in the reaction system was removed with nitrogen gas.

Next, while stirring, 11 g of a 5% aqueous ammonium persulfate solution and 4.5 g of a 5% aqueous sodium acid sulfite solution were added as polymerization initiators, and then the temperature was raised to 80'C in air, and further maintained at the same temperature for 3 hours. After that, water 23
(15.2% nonvolatile content, Brookfield viscosity at 25°C of 5500 cps, and pH of 5.1%).
An aqueous solution of an anionic copolymer of 0 was obtained. The weight average molecular weight of this anionic copolymer was 427,000.

Hereinafter, this aqueous solution will be referred to as rA-14.

Production Example 2 50% acrylamide 71% was placed in a 10100O four-bottle flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube. Iy and 663 J of water were weighed out, and oxygen in the reaction system was removed with nitrogen gas.

Next, the temperature was raised to 50°C with stirring, and then 0.36 g of 5% potassium persulfate was added, the temperature was raised to 70'C, and the temperature was further maintained for 3 hours. In order to hydrolyze acrylamide and introduce anionic groups, 48%
4.27 g of caustic soda was added and maintained at 70'C for 1 hour. After that, water 7209 and 62.5% sulfuric acid 7.89 were added to give a nonvolatile content of 5% and a viscosity of 11000 cps (25°C
), an aqueous solution of an anionic copolymer having a pH of 5.5 was obtained.

The weight average molecular weight of this anionic copolymer is 1800
I needed it at 000. Hereinafter, this aqueous solution will be referred to as rA-2J.

) Example 3 Before stirring, in a 10100O four-way flask equipped with a thermometer, reflux condenser, and nitrogen introduction tube, 50% acrylamide 1629.80% acrylic acid 5.4J, water 737s,
Weigh out u and 2.5 J of isopropyl alcohol,
The pH was adjusted to 5 to 5.5 with 8% caustic soda, and oxygen in the reaction system was removed with nitrogen gas.

Next, while stirring, 2.69 g of a 5% ammonium persulfate aqueous solution and 1.1 g of a 5% acidic sodium Vftite aqueous solution were added as polymerization initiators, and the temperature was increased from air temperature to 80'C.
The temperature was raised to 1, and maintained at roughly the same temperature for 3 hours.

After cooling this to 50℃, 37% formalin 19
．． 59 and 25.9 SJ of a 50% dimethylamine aqueous solution were added in this order. Hold at the same temperature for 1 hour, and the non-volatile content is 10.
5%, viscosity 530Q cps (25°C), pH 10
, 8 was obtained. The weight average molecular weight of this copolymer was 680,000. Hereinafter, this aqueous solution will be referred to as "rM-1".

Production Example 4 The amounts of water, 5% ammonium persulfate aqueous solution, and 5% acidic sodium sulfite aqueous solution were each 14589.0
．． 513.0.119 was used in the same manner as in Example 3, the non-volatile content was 5%, the viscosity was 6200 cps (25°
C) An aqueous solution of a cationic Mannich-modified copolymer having a pH of 10.4 was obtained. The weight average molecular weight of this copolymer was 1,630,000. Below, this aqueous solution is rM-
24.

Production Example 5 50% acrylamide 2403 and water 3577 were charged into a 1000+nQ four-way flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and oxygen in the reaction system was removed with nitrogen gas.

Next, the temperature was raised to 35°C while stirring, and then 6.83% of a 5% pertinent ammonium aqueous solution and 2.89% of a 5% acidic sodium sulfite aqueous solution were added as polymerization initiators, and the temperature was raised from room temperature to 80°C. The mixture was then kept at the same temperature for 3 hours. Add the condensate 3973 and non-volatile content 1
3% polymer with a viscosity of 4300 cps.

The above polymer 6709 was placed in a 1,000 mQ four-tube flask equipped with a stirrer, a thermometer, and a reflux condenser, and a mixed aqueous solution of 127 J of sodium hypochlorite containing 12.5% active ingredients and 24% caustic soda 197 was added. . Then, after the reaction was completed at 25°C for 1 hour, 15% of sodium sulfite was added.
Add aqueous solution 7.73, adjust to I)H4.5 with hydrochloric acid, add water to obtain a viscosity of 1400 cps at a non-volatile content of 13%.
(25°C) An aqueous solution of a cationic polymer (Hoffmann rearrangement product of polyacrylamide) was obtained. The weight average molecular weight of this polymer was 295,000. below,
This aqueous solution is referred to as rc-1J.

Production Example 6 Powdered acrylamide 75% was placed in a 10100O four-tube flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube. El, dimethylamine ethyl methacrylate 19
．． 7g, acrylic acid 4.59.98% sulfur M3.2a, 4
Prepare 8% caustic soda 4.23 and water 5659,
The temperature was raised to 50'C while stirring and introducing nitrogen gas. Then, 5
After adding 2.53% ammonium persulfate aqueous solution and 1.19% 5% acidic sodium nitrous acid aqueous solution, the temperature was raised from room temperature to 80°C and roughly maintained at the same temperature for 3 hours. Then, 333g of water was added, the non-volatile content was 10%, the viscosity was 6.
An amphoteric copolymer aqueous solution of 300 cps (25°C>, pH 4.4 was obtained. The weight average molecular weight of this copolymerization was 51
I needed it at 0000. Hereinafter, this aqueous solution will be referred to as rc-2J.

Production Example 7 A flask equipped with a stirrer, a thermometer, a dropping funnel, and a water separator was charged with 876 g of Adipine M and 300 y of water, and 618 g of diethylenetriamine was added dropwise while stirring.

Then, the internal temperature of the reaction system was gradually raised and kept at 180° C. for 4 hours to carry out a dehydration condensation reaction. After that, water 127
8y was gradually added to obtain a polyamide polyamine resin aqueous solution having a concentration of 50%.

Next, the above resin aqueous solution 1209 and water 859 were charged into a flask equipped with a stirrer, a thermometer, and a reflux condenser.
Add epichlorohydrin 377 with stirring and heat to 50'C.
The temperature was raised until After that, the reaction was continued while keeping it at the same temperature and measuring the viscosity of the contents, and the viscosity was 450c.
By adding 50 g of water and a predetermined amount of 35% sulfuric acid when ps is reached, the non-volatile content is 30% and the viscosity is 315 cp.
A cationic resin (epichlorohydrin modified product of polyamide polyamine) aqueous solution was obtained at 25° C. and pH 5.0. The weight average molecular weight of this resin was 92,000. Hereinafter, this aqueous solution will be referred to as "C-3". do.

Production Example 8 Powdered acrylamide 75% was placed in a 10100O four-bottle flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube. EEF, dimethylaminopropylacrylamide 18.59.98% Wt acid 9.43 and 522 g of water were charged, and the temperature was raised to 50'C while stirring and introducing nitrogen gas. Then, 2.3 g of 5% ammonium perwL acid aqueous solution and 5%
After adding 0.9 y of an aqueous solution of % acidic sodium sulfite, the temperature was raised from room temperature to 80'C, and roughly maintained at the same temperature for 3 hours. After that, add water 3689 and add 10% non-volatile content.
An amphoteric copolymer aqueous solution having a viscosity of 8100 cps (25°C) and a pH of 5.4 was obtained. The weight average molecular weight of this copolymer was 551,000. Below, this aqueous solution is rc
-4J.

Example 1 First, sulfuric acid band was added to a 1% slurry of L-UKP with a freeness of 460 Peng C3F (based on dry amount N, the same applies hereinafter) 2
%, 3%, or 4%, then add polymer (I> or polymer (I>) then polymer (■) to pulp at 0.2
% or 0.4%.

The freeness of the pulp slurry thus obtained was measured according to JIS P8121.

The results are shown in Table 1.

Porridge 1 In Table 1, (A-1/M-'l) the mixture is A.
1 shows an aqueous mixture of the present invention obtained by mixing -1 and M-1 in advance (the same applies hereinafter).

From Table 1, it can be seen that Nα6.12 and 1 using the filtering agent of the present invention
It is clear that the freeness of Sample No. 8 is significantly improved compared to when A-1 or M-1 is used alone or when both are added separately.

Note that workability was good in all cases.

Example 2 To a 1% slurry of corrugated wastepaper pulp with a freeness of 510 mQC3F, first 1% of sulfuric acid based on the pulp (on a dry weight basis, the same applies hereinafter) was added, and then various amounts of polymer (
I> or polymer (I> and polymer (II>) were added in sequence.

The freeness of the pulp slurry thus obtained was measured according to JIS P8121.

Workability was good in all cases. The results are shown in Table 2.

Table 2 Example 3 First, sulfuric acid was added to a 1% slurry of corrugated waste paper pulp with a freeness of 410 m12C3F (dry weight basis,
1% (the same applies hereinafter) was added, and then Polymer (1) or Polymer (1) and Polymer (II>) were added in this order.

The freeness of the pulp slurry thus obtained was measured according to JIS P8121.

Workability was good in all cases. The results are shown in Table 3.

Table 3 Example 4 Various aqueous mixtures shown in Table 4 were diluted with water to give aqueous solutions with non-volatile content of 4% and 1%. The stability of each of these aqueous solutions was investigated. The results are shown in Table 4.

Table 4 It is clear that Nos. 1 to 8, which are the aqueous mixtures of the present invention, have better stability than Nos. 9 to 16, which are the comparative aqueous mixtures.

Example 5 To a 1% slurry of corrugated wastepaper pulp with a beatingness of 480 mQC3F, first add 1% of sulfuric acid band to the pulp (on a dry weight basis, the same applies hereinafter), then add polymer (■) or polymer (I> and polymer (II>) were added in order.

The freeness of the pulp slurry thus obtained was measured according to JIS P8121.

The results are shown in Table 5.

Table 5 From Table 5, it is clear that in No. 3 using the drainage agent of the present invention, the drainage property was significantly improved compared to other cases. Note that workability was good in all cases.

Example 6 To a 1% slurry of corrugated waste paper pulp with a beatingness of 480 mQC3F, first add 1% of sulfuric acid band to the pulp (on a dry weight basis, the same applies hereinafter), and then add polymer (■) or polymer (I> and polymer (II>) were added in order.

The freeness of the pulp slurry thus obtained was measured according to JIS P8121.

Also, using the same pulp slurry, paper was made using a Tatsupi, Standard, and Sheet machine to have a basis weight of 1509/m. At this time, first, paper is made to have a weight of 75 g/m, and the wet paper before press dehydration is stacked with wet paper made in the same manner to form a single sheet of paper, and then press dehydrated for 5 minutes and the surface temperature After drying in a rotary dryer at 100°C for 4 minutes, the paper was conditioned at a temperature of 20°C and a humidity of 65% RH for over 24 hours, and the properties of the resulting paper were tested using the following method.

Compressive strength: JIS P8126 Bursting strength: JIS P8131 Interlayer peeling strength: J, Tappi No., 5-B
The results are shown in Table 6.

From Table 6, it is clear that Nα4 and 5 using the present invention water filtering agent have significantly improved freeness and paper strength and interlaminar strength compared to other cases. It is. Note that workability was good in all cases.

(that's all)

Claims (1)

[Claims] (1) A water filtering agent for papermaking comprising an aqueous mixture of an anionic polyacrylamide having a weight average molecular weight of 100,000 to 2 million and a cationic Mannitz-modified polyacrylamide having a weight average molecular weight of 100,000 to 2 million.