JPH0480924B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing cationically modified polyacrylamide, which has use as a papermaking additive. Conventionally, a well-known method for cationic modification of polyacrylamide is the so-called Hofmann decomposition reaction, in which amide groups are converted to amino groups by reacting with hypohalite under alkaline conditions, and the product is used as a papermaking additive. It is used. However, when reacting polyacrylamide and hypohalous acid in an alkaline region, the amount of alkali used is extremely important in designing the desired modified product; for example, if the amount of alkali is small, the reaction In many cases, gelation, which is thought to be caused by isocyanate groups, which are reaction intermediates, occurs before the reaction proceeds sufficiently.On the other hand, when the amount of alkali is large, hydrolysis of the amide groups in polyacrylamide proceeds as a side reaction, resulting in a large amount of gelation. Due to the formation of carboxyl groups and the formation of urea compounds, which are considered to be reaction products between adjacent amino groups and isocyanate groups, which are reaction intermediates, the problem arises that their functionality as papermaking additives deteriorates. Furthermore, since the amino group introduced by the Hofmann decomposition reaction is a primary amine, it is desired to improve its function as a papermaking additive, particularly from the viewpoint of PH presence. The present invention was carried out to overcome the problems of the above-mentioned Hofmann decomposition reaction. As a result of extensive research, the present inventors have determined that the reaction between polyacrylamide and hypohalite in an alkaline region can be expressed using the general formula (However, R ₁ and R ₂ are lower alkyl groups, X ^- ₁ is an anion, Y ₁ and Y ₂ are halogen groups, and P is an integer of 1 to 5.) Compound (1) represented by the general formula (However, R ₃ and R ₄ are lower alkyl groups, R ₅ is H or lower alkyl group, X ^- ₂ is an anion, and Q is 1 to 5
represents an integer. ) It has been found that the above object can be achieved by carrying out the reaction in the presence of a condensation product obtained by mixing the former and the latter at an equivalent ratio of 0.5 to 1.0 and condensing the mixture in an alkaline region, and the present invention (In the present invention, equivalent means the equivalent of acid, hydrochloric acid, or something similar.) An alkaline region with an equivalent ratio of compound (1) and compound (2) of 0.5 to 1.0. By conducting the Hofmann decomposition reaction in the presence of the products condensed below, the amount of alkali used can be reduced to approximately the equivalent of the available halogen in the hypohalous acid, which is a problem in the Hofmann decomposition reaction. The hydrolysis reaction of the amide group can be controlled. Furthermore, under the conditions of the present invention, the phenomenon of gelation described above can be avoided, but this is because the hydroxyl groups in the condensed compound combine with the isocyanate intermediate of the Hofmann decomposition reaction, resulting in cross-linking based on the isocyanate groups. This is thought to be to suppress the Compound (1) can be easily obtained by combining a salt of a secondary amine comprising a lower alkyl group (for example, dimethylamine hydrochloride) with epichlorohydrin. When the molar ratio of dimethylamine hydrochloride to epichlorohydon phosphorus is 1:2, the product is the following compound (3), and when the molar ratio is 2:3, compound (4) is obtained. However, when the molar ratio of dimethylamine and epichlor is set to 1:1, the condensation reaction proceeds to form a polymer compound. In this case, gelation during the above-mentioned Hofmann decomposition reaction becomes a problem. Therefore, the value of P in compound (1) is 1 to 5, preferably 1.
It is necessary to adjust the molar ratio of dimethylamine to epichlorohydrin so that it is ~3. Next, for compound (2), choline chloride [HOCH ₂ CH ₂ N(CH ₃ ) ₃ ] ⁺ C ₁ ^- , dimethylamino alcohol (CH ₃ ) ₂ NCH ₂ CH ₂ OH・, diethylamino alcohol (C ₂ H ₅ ) ₂ NCH ₂ CH ₂ OH and their quaternized products are used. As the quaternizing agent, lower alkyl halides such as methyl chloride and ethyl chloride, benzyl chloride, etc. can be used. The condensation reaction between compound (1) and compound (2) is carried out in an alkaline region, and the progress of the reaction is determined by the amount of alkali consumed. The condensation product is obtained by ether bonding compound (1) and compound (2). The molar ratio of compound (1) and compound (2) is 0.5 to 1.0, especially
0.75 to 1.0 is preferable, and if the molar ratio is 0.5 or less,
The presence of the dihalohydrin compound in the Hoffman decomposition reaction induces a crosslinking reaction between the polymers, and the reaction product becomes gel-like. The novel cationic polyacrylamide obtained by the present invention can be effectively used as a papermaking additive such as a paper strength agent, a water retention agent, a filler retention agent, and the like. Furthermore, when added alone or in combination with starch or the like between the layers of paperboard, etc., it has the effect of significantly improving the strength. Next, the present invention will be specifically explained with reference to Examples. Example 1 Acrylamide polymer (a) 320 g of acrylamide and 1167 g of water in an internal volume of 2
Place the contents in a four-necked flask and heat the contents to 49°C to prepare an aqueous solution containing 5.1 g of ammonium persulfate.
50g and an aqueous solution containing 0.51g of sodium sulfite.
When 10g was added, the temperature rose to 90°C. This temperature was maintained for 1 hour and the polymer concentration was 16.3.
%, viscosity 7500cpe (25℃, measured with a B-type viscometer,
An acrylamide polymer (a) (the same applies hereinafter) was obtained. 2. Cationic polyacrylamide (example of conventional product) Place 108.4 g of the above acrylamide polymer (a) in a 500 ml four-necked flask, add 1.8 g of sodium hypochlorite and 1.5 g of sodium hydroxide.
Add 32.8g of an alkaline sodium hypochlorite aqueous solution containing
Reaction was performed for 60 min. Thereafter, the pH was adjusted to 4.5 with hydrochloric acid to obtain a cationic polyacrylamide (conventional product) containing 10% active ingredient (by weight, same hereinafter). 3 Trial product 1 (Example of condensate of compound (1) and compound (2)) 45.2 g of a 50% aqueous solution of dimethylamine was placed in a four-neck flask with an internal volume of 500 ml, and 60.7 g of a 15% aqueous solution of hydrochloric acid was added while stirring. Then, 69.4 g of epichlorohydrin was gradually added, and the
C. for 2 hours to obtain a condensate with a molar ratio of dimethylamine and epichlorohydrin of 2:3.
Next, 69.8 g of choline chloride and 133.3 g of a 15% aqueous solution of sodium hydroxide were added to this, and the
The reaction was carried out at 50°C for 2 hours to obtain a reaction product (sample product 1) with a solid content of 20%. 4 Trial product 2 (second example of condensate of compound (1) and compound (2)) When manufacturing trial product 1, instead of choline chloride,
Substantially the same treatment was performed except that 52.2 g of NN-dimethylaminoethanol was added, and the solid content was 20.
% reaction product (sample 2) was obtained. 5 Sample product 3 (cation-modified polyacrylamide) In a four-necked flask with an internal volume of 500 ml, 108.4 g of the acrylamide polymer (a) and the sample sample 1,
After stirring and mixing, add 40 g of an alkaline sodium hypochlorite aqueous solution containing 1.8 g of sodium hypochlorite and 1.0 g of sodium hydroxide.
was added dropwise and reacted for 60 minutes at 25°C, and then the pH was adjusted to 4.5 with hydrochloric acid to obtain a cationic polyacrylamide containing 10% active ingredient (sample product 3). 6 Sample product 4 (cation-modified polyacrylamide) In a four-necked flask with an internal volume of 500 ml, 108.4 g of the acrylamide polymer (a) and the sample sample 1,
After stirring and mixing 38.3 g of sodium hypochlorite and 70 g of alkaline sodium hypochlorite aqueous solution containing 3.5 g of sodium hypochlorite and 2.0 g of sodium hydroxide.
g was added dropwise, and the mixture was reacted for 60 minutes at 25°C, and then the pH was adjusted to 4.5 with hydrochloric acid to obtain a cationic polyacrylamide containing 10% of the active ingredient (sample product 4). 7 Trial product 5 (cation-modified polyacrylamide) The manufacturing method of trial product 3 was performed, except that 28.6 g of trial product 2 was added instead of the above-mentioned trial product 1. A cationic polyamide (sample product 5) was obtained. Note that the cation equivalents and anion equivalents of the conventional product examples and prototype examples 2, 3, and 4 are shown in Table 1.

[Table] However, the equivalent weight was measured according to the following procedure. Cation equivalent: Accurately weigh approximately 100 mg of the sample, transfer it to a 100 ml beaker, and add 50 ml of purified water. Stir with a magnetic stirrer for 5 minutes to completely dissolve the sample, and then
Add 5 ml of the specified sulfuric acid, and titrate with a 1/400 normal polyvinyl potassium sulfate aqueous solution using toluidine blue as an indicator. Anion equivalent: Accurately weigh approximately 100 mg of the sample and completely dissolve it in 50 ml of purified water. Add 1 ml of 1/2 N aqueous sodium hydroxide solution, and while stirring, add 10 ml of 1/200 N aqueous polyamine sulfone solution.
Add. The polyamine sulfon present in excess is back titrated with a 1/400 normal polyvinyl potassium sulfate aqueous solution using toluidine blue as an indicator. The results of the performance test of the above cationic polyacrylamide as a paper-making chemical will be described below. Test Example 1 Using NUKP (CSF = 450ml), aluminum sulfate was added at 1% of the pulp to a slurry with a pulp concentration of 3%, and 0.3% of the cationic acrylamide sampled above was added to the pulp.
%, 0.5%, and 0.7%, and after stirring for 5 minutes, paper was made to have a basis weight of 60 g/m ² using a Tatsupi standard sheet machine. The paper was then dehydrated by pressing at 4 kg/cm ² for 1 minute and then dried at 105° C. for 3 minutes. Thereafter, the sheet was conditioned at 20°C and 65% relative humidity for 24 hours, and the specific bursting strength was measured. The results are shown in Table 2.

【table】

[Table] Test example 2 L/N (70/30) BKP (CSF = 430) as the upper layer
ml), used newspaper waste paper (CSF = 300 ml) as the lower layer, and for the slurry with a pulp concentration of 3%, the upper layer contained aluminum sulfate at 2% relative to the pulp, and 0.15% cation-modified polyacrylamide of the trial product and conventional product. After stirring for 5 minutes, paper was made to a basis weight of 80 g/m ² using a tapi standard sheet machine to obtain a wet paper of L/N BKP. On the other hand, 0.15% of cation-modified polyacrylamide of the trial product and the conventional product was added to the lower layer, and the same operation as L/N BKP was repeated to obtain a wet paper of waste newspaper. After overlapping both wet papers and dehydrating them for 2 minutes at 4Kg/ ^cm2 ,
It was dried at 110°C for 3 minutes. After that, heat the sheet at 20℃.
After conditioning at a relative humidity of 65% for 24 hours, the interlaminar strength was measured according to the Japan Tappi No. 18m method. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1. The reaction between polyacrylamide and hypohalite in an alkaline region is expressed by the general formula (However, R ₁ and R ₂ are lower alkyl groups, X ^- ₁ is an anion, Y is a halogen group, and P is an integer from 1 to 5.) Compound (1) represented by the general formula (However, R ₃ and R ₄ are lower alkyl groups, R ₅ is H or lower alkyl group, X ^- ₂ is an anion, and Q is 1 to 5
represents an integer. ) with compound (2), 0.5
1. A method for producing cation-modified polyacrylamide, which is carried out in the presence of a condensate in an alkaline range of a mixture with a quantitative ratio of ~1.0.