JP2660263B2 - Papermaking method - Google Patents

Description

The present invention relates to a papermaking method.

More specifically, the present invention relates to a method for papermaking by adding an aqueous solution of a cationic polyacrylamide as a pulp dispersing agent to a paper stock to which a water-soluble cationic resin has been added.

[Conventional technology]

Generally, at the time of making Japanese paper, a dispersing agent called a tackifier is added in order to prevent entanglement and sedimentation of the fibers in the pulp dispersion liquid and to uniformize the paper formation.

Conventionally, various natural polymer substances such as mucus extracted from the roots of the trolley mallow, polyethylene oxide, polyacrylamide, and various other synthetic water-soluble polymer substances have been used as this adhesive, but today their performance is good. Therefore, polyacrylamides, particularly anionic polyacrylamide, are widely used. The mechanism of action is believed to be due to the adsorption of the anionic polymer on the pulp fibers, the dispersion of the fibers by the repulsive action of the ionic groups, and the prevention of aggregation, entanglement and sedimentation.

In addition, various water-soluble cationic resins such as urea formalin resin, melamine resin, polyethyleneimine, polyamide polyamine, etc. are added to the stock to improve the wet strength and dry strength of the paper, or to improve the yield of the filler. Often used.

However, if an anionic polyacrylamide-based dispersing agent is added to such a paper stock to which a water-soluble cationic resin has been added, the pulp fibers in the paper stock will coagulate, resulting in poor paper formation or poor papermaking properties. Problems such as sluggishness occur. To solve this problem, a method of adding a polyphosphate as an anti-agglomeration agent to a stock to which a water-soluble cationic resin is added and then adding an anionic polyacrylamide (Japanese Patent Laid-Open No. 48-63009), or And the use of a copolymer of acrylamide and 2-acrylamido-2-methylpropanesulfonate as a dispersing viscosity agent (Japanese Patent Publication No. 60-43479).

[Problems to be solved by the invention]

However, when an anti-agglomeration agent such as polyphosphate is added, it is necessary to increase the number of steps, and it is necessary to reliably control the conditions of the amount added. There is a problem that the effect of the water-soluble cationic resin as a paper strength enhancer is reduced by the agent.

In view of such a situation, the present inventors have earnestly studied a rational papermaking method and completed the present invention.

[Means for solving the problem]

The gist of the present invention is that a urea formalin resin, a melamine resin, a polyethyleneimine,
A papermaking method characterized by adding a water-soluble cationic resin selected from polyamidepolyamine and polyamide-epichlorohydrin resin, then adding cationic polyacrylamide as a dispersing agent, and then papermaking.

That is, the method of the present invention is characterized by using a cationic polyacrylamide which has not been conventionally used as a pulp dispersion thickener.

As the water-soluble cationic resin as a paper strength enhancer used in the present invention, urea formalin resin, melamine resin,
Polyethylene imine, polyamide polyamine, and polyamide-epichlorohydrin resin are used.

The cationic polyacrylamide used in the present invention is obtained by copolymerizing an acrylamide monomer and a cationic vinyl monomer having a tertiary amine neutralized salt or a quaternary ammonium salt. Water-soluble copolymer obtained.

Examples of the cationic vinyl monomer to be a copolymerization component include dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylamide, dimethylaminopropyl acrylamide, and other neutralizing salts, And quaternary ammonium salts.

Although this cationic polyacrylamide acts as a dispersing viscosity agent, since it is cationic, it does not react with the water-soluble cationic resin added as a paper strength enhancer, and thus does not require the addition of an anti-agglomeration agent. The papermaking process is simplified.

Further, the copolymerization composition ratio and molecular weight of the cationic polyacrylamide are not particularly limited, but in order to exhibit a sufficient dispersing effect, the content of the cationic vinyl monomer is 10%.
It is preferably about 40% by weight. Also, when expressed in terms of the cation equivalent value at pH 4, the cation equivalent value of the cationic polyacrylamide is preferably about 0.5 to 2.0 meq / g, and more preferably about 1.0 to 1.5 meq / g. Further, the intrinsic viscosity [η] serving as an index of the molecular weight is 1N-NaNO
₃ , It is preferable that the measured value at 30 ° C. is 10 dl / g or more.

The cationic polyacrylamide of the present invention can be produced by a known polymerization method such as aqueous solution polymerization, suspension polymerization, precipitation polymerization, and is usually produced by aqueous solution polymerization using an azo or redox polymerization catalyst. The gel copolymer can be dried and pulverized to obtain a powder.

In the papermaking process, the cationic polyacrylamide is usually added to the stock as a 0.05 to 0.2% aqueous solution.
The amount added to the pulp may be about 0.05 to 0.5%, and more preferably about 0.1 to 0.3%.

〔Example〕

Hereinafter, the present invention will be described by way of examples. The pulp dispersibility, the pulp dispersion ratio, the anti-freezing degree, and the cation degree were evaluated by the following methods.

(1) Pulp dispersibility The presence or absence of aggregation is visually determined.

(2) Pulp dispersion ratio 1 g of pulp stock beaten to a Canadian freeness of 600 to 700 ml is uniformly dispersed in water 1 and injected into one measuring cylinder, and the pulp interface is settled for 200 ml after the time to (second).
, And a settling time t when a predetermined amount of a thickener is added
(Seconds) is measured and calculated by the following equation.

Pulp dispersion ratio = t / to × 100 A large value of the pulp dispersion ratio means that the sedimentation speed of the pulp fiber is low, that is, it is desirable in terms of paper quality (formation).

(3) Anti-freeness Measured in the following manner based on JIS P8121. The measured freeness value Vo ml of only the pulp slurry is determined, while the measured freeness value V ml when the tackifier composition is added is determined, and the anti-freeness value is measured by the following formula.

Anti-freeness = Vo-V Although the anti-freeness is extremely high, the production is hindered. However, it is preferable that the anti-freeness is high as long as productivity is not hindered.

(4) Cationicity Take 90 ml of deionized water in a conical beaker, add 10 ml of a 500 ppm solution of the sample polymer, adjust to pH 4.0 with aqueous hydrochloric acid, and stir for about 1 minute. Next, add 2-3 drops of toluidine blue indicator and add N / 400 polyvinyl potassium sulfate (PVS
K) Titrate with reagent. The titration speed is 2 ml / min, and the end point is when the sample changes color from blue to magenta and is held for 10 seconds or more.

 The degree of cation is determined by the following formula.

Examples 1 to 4 A pulp stock beaten to 650 ml of Canadian freeness was decomposed into water to prepare a 0.1% pulp suspension. 0.7% of the sponge 557H (water-soluble polyamide-epichlorohydrin resin) was added.

Next, 0.2% (based on pulp) of a cationic polyacrylamide (abbreviated as polymer) consisting of a cationic vinyl monomer and acrylamide shown in Table 1 was added to each of them to evaluate pulp dispersibility and the like. The results are shown in Table 1.

In each case, the papermaking properties were good, and it was found that good results could be obtained without using an anti-agglomeration agent (dispersion aid).

Comparative Example 1 In place of cationic polyacrylamide, a partial hydrolyzate of polyacrylamide (anion degree: -2.2 meq / g,
Using [η] 18.0), the papermaking properties were evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained. The pulp was flocculated and poorly dispersible.

Comparative Example 2 Instead of cationic polyacrylamide, a copolymer of acrylamide and acrylamide-2-methylpropanesulfonate (anionic degree -1.6 meq / g, [η])
18.0), and the other conditions were the same as in Example 1 to evaluate the papermaking properties. The results shown in Table 1 were obtained.

Comparative Example 3 The papermaking properties were evaluated in the same manner as in Example 1 except that cationic polyacrylamide was not added, and the results shown in Table 1 were obtained.

Examples 5 and 6 Pulp stock beaten to 650 ml of Canadian freeness was dispersed in water to prepare a 0.1% pulp suspension, and sponge 557H was added thereto as a water-soluble cationic resin for enhancing paper strength.
0.5% was added.

Next, 0.2% (based on pulp) of a cationic polyacrylamide comprising a cationic vinyl monomer and acrylamide shown in Table 1 was added to each of them to evaluate the dispersibility of the pulp and the like, and the results are shown in Table 1. .

Comparative Example 4 The same polyacrylamide partial hydrolyzate as in Comparative Example 1 was used in place of the cationic polyacrylamide, and the papermaking properties were evaluated in the same manner as in Example 5 under the other conditions.
The dispersibility of the pulp was poor.

Comparative Examples 5 to 7 In Comparative Example 4, before adding the hydrolyzate of polyacrylamide, sodium hexametaphosphate as an anti-agglomeration agent was added to the stock in 0.5 ppm (Comparative Example 5) and 1.0 ppm, respectively.
(Comparative Example 6) and 2.0 ppm (Comparative Example 7) were added to evaluate papermaking properties. In each case, although the pulp dispersion ratio was improved as compared with Comparative Example 4, it did not reach Examples 5 and 6.

[Effect of the Invention] According to the method of the present invention in which the dispersibility of pulp fibers is good,
Paper with good formation can be obtained. Further, since addition of an anti-agglomeration agent is unnecessary, papermaking can be performed in a simplified process.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-252398 (JP, A) JP-A-62-85100 (JP, A) JP-A-62-15391 (JP, A) JP-A 61-252391 271012 (JP, A)

Claims (1)

(57) [Claims] 1. A water-soluble cationic resin selected from urea formalin resin, melamine resin, polyethyleneimine, polyamide polyamine and polyamide-epichlorohydrin resin is added to a paper stock as a paper strength enhancer, and then cationic polyacrylamide is dispersed in the paper material. A papermaking method comprising adding paper as an agent and then papermaking.