JP3064230B2 - Papermaking additives - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking additive, and in particular, only by mixing a specific liquid polymer with an acrylamide-based paper-strengthening agent, a stable and excellent paper-strengthening effect is exhibited. The present invention relates to a papermaking additive which simultaneously exhibits high one-pass retention and drainage.

[0002]

2. Description of the Related Art As a paper strength enhancer, an anion-modified product of polyacrylamide was initially developed, but a cation-modified product began to appear when the papermaking method in the neutral to weakly alkaline region began to spread, and at present, the paper-forming material has been developed. Amphoteric modified products having high adsorptive power and paper strength are rapidly spreading.

[0003] In the field of papermaking using paper strength agents, there are overwhelmingly many papermakings related to paperboard. Since paperboard has a large basis weight, most of the cases use a kind of coagulant called a drainage improver in addition to a paper strength enhancer. The paper strength enhancer is the same polyacrylamide-based polymer compound, but unlike the flocculant, the cross-linking and adsorbing effect of high molecular weight polyacrylamide is small, so that the so-called flocculation effect is weak. The reason for this is that the paper strength enhancer has a small number of molecular weights on the order of 1 to 2 orders, and there are many ideas such as monomer composition and polymerization method to suppress the coagulation action and to improve the adsorptivity to pulp and the adhesion between pulp. Has been established. Therefore, the paper strength enhancer alone can be used for drainage and retention (so-called one-pass retention),
Alternatively, it is difficult to increase water squeezing in the press part. Therefore, at present, it is inevitable to use a drainage improver in a machine in which productivity must be increased. In this situation, attempts have been made to improve the system. For example, JP-A-3-227487 describes a method of mixing an acrylamide-based paper strength enhancer with an acrylamide polymer having a molecular weight of 2,000,000 to 20,000,000. However, there is no description about improvement of drainage, and the purpose is to enhance paper strength. In addition, the mixing property of the two is poor and it is practically difficult to carry out the technique.

[0004]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a water-soluble polymer dispersion and / or a polyacrylamide-based paper strength enhancer dispersed in an aqueous salt solution. The present invention has been found that, by mixing with a water-in-oil type water-soluble polymer emulsion, not only a stable and excellent paper strength enhancing effect is exhibited, but also high one-pass retention and drainage are exhibited at the same time.

Next, the present invention will be described specifically. The paper strength agent used in the present invention is a polyacrylamide-based polymer. Paper strength enhancers can be broadly classified into starch-based and polyacrylamide-based, but starch-based paper strength enhancers are not suitable because of poor compatibility with the other component of the present invention, a polymer dispersion or emulsion. Polyacrylamide paper strength agents can be further classified into nonionic, cationic, amphoteric and anionic. Since the nonionic property is used as a surface coating agent, it departs from the spirit of the present invention, but the ionic property can be any of anionic, cationic or amphoteric. In particular, amphoteric is the most preferable as a paper-strength enhancer used in the present invention because of its excellent paper-strength effect.

Next, the paper strength enhancer used in the present invention will be specifically described. The polyacrylamide-based compound can be produced by radical copolymerization with an acrylamide monomer and a cationic and / or anionic, and further with another nonionic monomer. The cationic monomer may be dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide or dimethyldiallylammonium chloride, or an organic or inorganic salt thereof, or a quaternary ammonium salt. can give.
Anionic monomers are acrylic acid, methacrylic acid, 2-
Acrylamide 2-methylpropanesulfonic acid, maleic acid, itaconic acid, styrenesulfonic acid, and sodium, potassium, ammonium salts thereof and the like. Nonionic monomers other than acrylamide are acrylonitrile, N-vinylpyrrolidone, vinyl acetate,
2-hydroxy (meth) acrylate, dimethylacrylamide, N-isopropylacrylamide and the like can be mentioned.

Further, it is possible to copolymerize a cross-linkable polyfunctional monomer for the purpose of improving the performance of the polymer. For example, N, N'-methylenebisacrylamide,
N-allylacrylamide, N, N-diallylacrylamide, ethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate. Alternatively, N, N dimethylacrylamide or the like is used.

The polymerization is carried out using a general organic or inorganic peroxide, or a redox system or an azo-based initiator in combination with such a peroxide. The polymerization method can be carried out by aqueous solution polymerization, dispersion polymerization in a salt solution or polymer solution, or inverse-phase emulsion polymerization, but aqueous solution polymerization is most suitable as the paper strength enhancer of the present invention. When producing anionic polyacrylamide, the molar fraction of the anionic monomer is generally 5 to 30 mol%, but is preferably 6 to 1 mol%.
5 mol% is preferred. When producing a cationic polyacrylamide, the molar fraction of the cationic monomer is generally 5 mol% to 30 mol%, but is generally 7 mol% to 20 mol%.
Is preferred. Further, the amphoteric polyacrylamide contains 1 mol% to 30 mol% of anionic monomer, 1 mol% to 30 mol% of cationic monomer, preferably 2 mol% to 20 mol% of anionic monomer, 4 mol% or more
20 mol%.

The molecular weight of the polyacrylamide paper strength enhancer is not necessarily the same depending on the anionic, cationic or amphoteric ionicity, but is usually 0.1 to 3.0 in intrinsic viscosity, preferably 0. 0.3 to 2.0 (measured at 25 ° C. in 1N saline).

Next, a salt aqueous polymer dispersion or an oil-water type water-soluble polymer emulsion to be mixed with the paper strength enhancer will be described. First, the salt aqueous polymer dispersion will be described. The dispersion can be easily produced according to JP-A-62-20502. Ammonium sulfate,
A cationic polymer or an organic polyhydric alcohol is allowed to coexist in an aqueous salt solution such as sodium sulfate or sodium chloride, and a monomer such as acrylamide or acryloyloxyethyldimethylbenzylammonium chloride is copolymerized. Water-in-oil polymer emulsions can also be prepared by using a water-insoluble organic solvent as a dispersion medium by a known technique.
The monomer aqueous solution is emulsified into a water-in-oil type with an emulsifier having a low B, followed by polymerization. Thereafter, a highly hydrophilic emulsifier called a phase change agent is added to obtain a water-soluble emulsion.

The reasons for using a water-soluble polymer dispersion and / or an oil-water type water-soluble polymer emulsion in the present invention are as follows. The polymer concentration of the dispersion is usually 1
5% to 30%, and emulsions are usually 15% to
50%. Therefore, when mixed with a paper strength agent, a product having a high concentration can be produced. Further, there is an advantage that both liquids are easily mixed even if the molecular weight of the polymer constituting the dispersion or emulsion is high. These can be produced by the above-mentioned polymerization method using acrylamide and a cationic monomer as main components. If necessary, it is possible to add an anionic monomer to make the polymer amphoteric, or to add another nonionic monomer to modify the polymer.

The mole fraction of acrylamide in the polymer is usually from 0 to 95 mol%, the mol% of the cationic monomer is usually from 5 mol% to 100 mol%, and the mole fraction of the anionic monomer is % Is usually 2 mol% to 50 mol%. The mol% of the nonionic monomer other than acrylamide is usually 2 mol% to 30 mol%.

Further, the intrinsic viscosity of the polymer constituting the dispersion or emulsion used in the present invention is usually 3 or more, preferably 5 or more. When the intrinsic viscosity is less than 3, not only the drainage on the wire becomes insufficient, but also the paper strength effect decreases, which is not suitable.

Next, the mixing of the acrylamide-based paper strength enhancer, the polymer dispersion and the emulsion during the production of the papermaking additive of the present invention will be described. As for the mixing ratio, the polymer solid content ratio between the paper strength enhancer and the polymer dispersion and / or emulsion is usually from 99: 1 to 70:30, preferably from 97: 3 to 85:15, more preferably from 97: 3 to 85:15. 9
6: 4 to 90:10. If the solid content ratio of the dispersion and / or the emulsion is 1% or less, drainage on the wire is not sufficient, and if it is 30% or more, the cohesive strength increases and the strength of the formed paper decreases, which is not preferable.

As the mixing method, the dispersion and / or the emulsion may be added to the paper strength agent, or vice versa. At that time, even if it is added while stirring,
After the addition, the mixture may be stirred. The present invention has a great feature in that the mixing property is very good.

The papermaking additive of the present invention can reduce the apparent viscosity by adding inorganic salts such as sodium chloride, potassium chloride, sodium sulfate and ammonium sulfate. More specifically, adding inorganic salts to the paper strength agent in advance and then adding a polymer dispersion and / or emulsion is effective in lowering the apparent viscosity after mixing.

Next, a method of adding the papermaking additive of the present invention to a papermaking system will be described. Since the papermaking additive of the present invention is basically a paper strength enhancer, the basic addition method is to add it to a machine chest or a line between the machine chest and a fan pump. However, if you are considering how to use for the purpose of improving drainage and total yield, between the fan pump and the screen,
Alternatively, the location of the addition before or after the screen is worth considering.

Although the papermaking additive of the present invention improves drainage and squeezing properties by itself, it is of course possible to use it in combination with a drainage improver. At that time, the amount of the drainage improver currently used can be reduced, which is useful for cost reduction. Further, compared with the conventional paper strength enhancer, the yield of fine fibers and the like is improved, so that the paper strength can be expected to be increased.
The amount of addition is 0.005% to 3% per papermaking raw material if the purpose is to improve paper strength, and 0.002% to 0.5% if the purpose is to improve drainage or yield. It is a guide.

[0019]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which should not be construed as limiting the scope of the present invention.

[Production Example of Paper Strengthening Agent Used in the Present Invention]
A monomer having a composition shown in Table 1 is dissolved in ion-exchanged water to a concentration of 32%, and the pH of the solution is adjusted to 3.5. The temperature of the monomer aqueous solution was cooled to 8 ° C., and while maintaining the temperature, N ₂ gas was flowed for 30 minutes to remove oxygen in the solution. The polymerization is initiated by adding 0.2% by weight of ammonium peroxodisulfate and 0.5% by weight of sodium bisulfite per monomer. When viscosity is observed in the solution
The supply of N ₂ gas is stopped, and the mixture is removed from the water bath at 8 ° C. and the polymerization is continued. After 5 hours, the intrinsic viscosity of each strength agent in 1N saline is measured at 25 ° C.

[Table-1]

[Production Example of Water-Soluble Polymer Emulsion Used in the Present Invention] The weight ratio of water phase to oil phase is 70:30, monomer concentration in water phase is 35%, and Supersol LA is used as a dispersion medium in oil phase. Using -30 (manufactured by Idemitsu Petroleum), 1.8% of Hypermer B-246 (manufactured by ICI) and 6.9% of Span 80 were added per oil phase, and dissolved in a dispersion medium. The mixture was mixed with the polymer solution and emulsified with a homogenizer AM (manufactured by Nippon Seiki) at 10,000 rpm for 15 minutes. This was charged into a reaction vessel equipped with a stirrer, kept at 50 ° C. and replaced with N ₂ for 30 minutes, and then azobisisobutyronitrile was added at 0.02% by weight per monomer to carry out polymerization for 6 hours. Thereafter, 3.5% of a solution was added to Emulgen 409P (manufactured by Kao) as a phase inversion agent. Thereafter, the intrinsic viscosity in 1N saline was measured at 25 ° C. Table 2 shows the results.

[Table-2]

[Production Example of Water-Soluble Polymer Dispersion Used in the Present Invention] Polyacryloyloxyethyltrimethylammonium chloride 3% (20% concentration, 5000 c
p, 25 ° C.), glycerin, 1.0%, ammonium sulfate, 22.6%, and monomer concentration of 17% (all by weight relative to the total amount). The mixture was kept at 40 ° C. with stirring, and after substituting with N _{2 for} 30 minutes, VA-044 was used as an initiator in an amount of 0.04 per monomer.
Add 2% by weight and polymerize at 40 ° C for hours. Five hours later, VA-044 was further added at 0.01% (by weight), and polymerization was continued for five hours. After the polymerization, the intrinsic viscosity in 1N saline was measured at 25 ° C. Table 3 shows the results.

[Table-3]

[0023]

[Trial Production Examples 1 to 20] The papermaking additive of the present invention was produced using the paper strength enhancer, the water-soluble polymer emulsion and the water-soluble polymer dispersion prepared in the Production Examples. According to the mixing ratio shown in Table 4, the emulsion or dispersion was added to the paper strength agent with stirring and mixed. Also, 4% salt based on the weight of the liquid was added to and dissolved in the paper strength enhancer, and then an emulsion or dispersion was added and mixed. Then, B
The viscosity at a polymer concentration of 30% at 25 ° C. was measured with a mold viscometer. Table 4 shows the results.

[Table-4]

[0024]

Examples 1 to 16 Each of the papermaking additives of Experimental Examples 1 to 20 was tested for drainage and paper strength. Paper mill liner paper charge (pH 5.46, SS content 3.9%,
0.17%) was diluted to 0.3%, and 1000 ml was collected and stirred at 300 rpm while 2% of a sulfuric acid band, 0.2% of an emulsion type rosin sazu, and a papermaking additive of the present invention were added.
After adding 4% at intervals of 20 seconds each, the mixture is put into a Tappi Standard Freeness Tester, and the amount of drainage is measured.
After the same amount of chemical addition and stirring were performed, paper having a target basis weight of 100 g / m ² was formed on a Tappi Standard handmade paper machine, and the humidity was adjusted in a measurement chamber at a humidity of 60% and a temperature of 20 ° C. for 12 hours. Thereafter, the burst strength was measured. Table 5 shows the results.

[Table-5]

[0025]

Comparative Examples 1 to 7 A drainage test and a paper strength test were conducted under the same conditions as in Examples 1 to 16. A commercial product for comparison is Hopron 106 (manufactured by Mitsui Toatsu) as a paper strength agent.
Is added, as Hymoloc DR as a drainage improver
-7300 (manufactured by Hymo), when no paper-strength enhancer was added, or when no paper-strength enhancer and drainage improver were added, the prototype 23 in which the intrinsic viscosity of the polymer was less than 3
Papermaking Additives Prototype 110 and Prototype 118 Mixed with Prototype 31 and Papermaking Additives Prototype 1 with Different Mixing Ratio
19 and prototype 120 were tested. Table 6 shows the results.

[Table-6]

[0026]

The use of the papermaking additive of the present invention not only improves the drainage of water on the wire and the water squeezing in the press part during the production of paperboard, but also improves the paper strength and the total yield. The reduction of chemicals and the improvement of productivity can be expected, and the contribution to the paper industry is significant.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-370295 (JP, A) JP-A-6-329866 (JP, A) JP-A-50-72982 (JP, A) (58) Survey Field (Int. Cl. ⁷ , DB name) D21H 17/00-17/74

Claims (5)

(57) [Claims] 1. A polymer constituting a water-soluble polymer dispersion and / or a water-in-oil type water-soluble polymer emulsion in which an inorganic salt is added to a polyacrylamide paper strength enhancer and then dispersed in an aqueous salt solution. Has an intrinsic viscosity of 3 or more (1N
A water-soluble polymer dispersion and / or a water-soluble polymer emulsion (measured at 25 ° C. in NaCl). 2. The method according to claim 1, wherein the polyacrylamide paper strength enhancer is a polymer formed from a monomer mixture comprising at least an anionic monomer, a cationic monomer, and acrylamide. The papermaking additive as described. 3. The ratio of the polymer solid content of the water-soluble polymer dispersion and / or the water-in-oil type water-soluble polymer emulsion dispersed in a polyacrylamide paper strength agent and an aqueous salt solution to 99: 1. 3. The papermaking additive according to claim 1, wherein the ratio is 70:30. 4. A mixed solution of a polyacrylamide paper strength agent and a water-soluble polymer dispersion and / or a water-in-oil type water-soluble polymer emulsion dispersed in an aqueous salt solution has a polymer concentration of 20% by weight or more. The papermaking additive according to any one of claims 1 to 3, which is 40% by weight or less. 5. A water-soluble polymer dispersed in an aqueous salt solution.
5. The polymer according to claim 1, wherein the polymer constituting the dispersion and / or the water-in-oil type water-soluble polymer emulsion is a polymer containing at least acrylamide and a cationic monomer mixture. The papermaking additive as described.