JPH0941290A - Papermaking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a paper having excellent paper strength, improved in yield and water filtering property by adding a cationic or amphoteric polymer and a reaction product of a sulfonated amino resin and an amino group-containing material to a papermaking raw solution containing cellulosic fibers and an inorganic filler, and subjecting the mixture to papermaking. SOLUTION: A papermaking raw solution containing (A) cellulosic fibers and (B) an inorganic filler such as kaolin in added and dispersed with a sol of particles having 1-100nm primary particle diameter comprising (C) a cationic or amphoteric starch, an acrylamide derivative, cationic or amphoteric guar gum, polydimethylamioethyl methacrylate, polyethyleneimine, a polyamide- polymamine-epichlorhydrin resin or their mixture and (D) a sulfonate-containing melamine-formaldehyde condensate obtained by reacting a sulfonated amino resin with an amino group-containing material such as melamine, etc., at a weight ratio of (the former : the latter) of 1:(0.05-3), subjected the mixture to papermaking, dehydrating and drying to obtain the objective paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking method comprising making a papermaking stock solution containing cellulose fibers or a cellulose fiber and an inorganic filler, dehydrating and then drying the papermaking paper without deteriorating the paper strength and paper quality of the product. The present invention relates to a papermaking method for improving the production efficiency in a papermaking step and a drying step by sufficiently increasing the yields of cellulose fibers and inorganic fillers in the step and increasing drainage.

[0002]

2. Description of the Related Art Cellulose fibers or papers containing cellulose fibers and an inorganic filler as main components are generally obtained by dispersing and disintegrating cellulose pulp in water, adjusting the concentration and adding fillers and other additives as desired. The papermaking stock solution is supplied to the paper machine, and it is made through each process of dehydration and drying.
Then, for the purpose of improving the yield of the cellulose fiber and the filler, improving the paper strength, improving the paper quality, improving the productivity, etc., improvement of the device, improvement of various additives such as cationized starch, improvement of the papermaking process, etc. were carried out. Came.

Conventionally, an acidic papermaking method has been generally used in which aluminum sulfate is used as a fixing agent for a flocculant and a sizing agent, and an anionic organic polymer is used as a paper strength enhancer and a yield improver. In recent years, the amount of inorganic filler added has increased for the purpose of cost reduction and paper quality improvement, and the shortage of high-quality pulp and the use of low-quality pulp for cost reduction have increased. The speed is getting bigger. In addition, the acidic papermaking method that uses a large amount of aluminum sulfate is likely to be the neutral papermaking method due to the deterioration of paper durability, insufficient reuse of white water, facility corrosion, and the inability to use calcium carbonate as an inorganic filler. It has become. For these reasons, sufficient effects cannot be obtained by the methods or additives established in the conventional acidic papermaking, so that development of a yield improving agent and an improving method have been particularly demanded and various proposals have been made.

The use of cationized starch for the convenient agglomeration of paper and for improving the strength of the paper has been known for some time. Japanese Patent Publication Sho 55-6
Japanese Patent Laid-Open No. 55-12824 discloses a method in which a cationic component such as cationized starch and acrylamide copolymer is combined with an anionic component such as natural starch and carboxymethyl starch. There has been proposed a method of using a hydrophilic resin emulsion and an anionic water-soluble polymer in combination. Also,
Japanese Unexamined Patent Publication No. 60-259699 discloses a method of making a paper by adding a zeta-potential adjusting agent containing a sulfone group-containing melamine-formaldehyde condensate as an active ingredient at the time of making a paper by adding an amphoteric polyacrylamide strength enhancer. Has been described. Japanese Unexamined Patent Publication (Kokai) No. 2-14096 discloses a method of adding a cationized starch and an anionic polymer in an amount of 0.2 to 15% by weight to the cationized starch.
A method in which modified cationized starch obtained by cooking is used in combination is proposed. As this anionic polymer, a sulfo group-containing melamine-formaldehyde condensate has been proposed.

[0005]

Problems to be Solved by the Invention JP-A-55-6587
In the method of using a combination of a cationic organic polymer and an anionic organic polymer as proposed in JP-A-55-12824 and JP-A-55-12824, the yield of cellulose fiber and inorganic filler can be improved and the paper strength can be improved. However, since the drainage is poor, the productivity is low, and the quality of paper such as formation is deteriorated.

The combination of an amphoteric polyacrylic amide and a zeta potential adjusting agent containing a sulfone group-containing melamine-formaldehyde condensate as an active ingredient proposed in JP-A-60-259699 can improve paper strength. However, since the cohesive force is weak, the yield of the cellulose fibers and the inorganic filler is poor, and the drainage is also poor. In the combination of the modified cationized starch and anionic polymer of a sulfo group-containing melamine-formaldehyde condensate proposed in JP-A-2-14096, the yield is good and the drainage is good, but the cohesive property is still unsatisfactory. However, there are drawbacks such that sufficient yield cannot be obtained depending on the papermaking conditions and it is difficult to control the performance of the modified cationized starch.

The present invention uses a product obtained by reacting a sulfonated amino resin and a substance containing an amino group, and thereby has a sufficient yield and a good drainage in a papermaking process under acidic and neutral conditions. Is provided.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a papermaking method in which a papermaking stock solution containing cellulose fibers (A) or the same and an inorganic filler (B) is made into paper, dehydrated and then dried. Is a papermaking method characterized by adding a cationic or amphoteric polymer (C), a product (D) obtained by reacting a sulfonated amino resin and an amino group-containing substance to papermaking.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The cellulose fiber (A) used in the present invention is obtained by mechanically or chemically treating a plant raw material. Pulp is a collection of cellulose fibers extracted from plant raw materials, which is an intermediate product used in the manufacture of paper. Examples of the plant raw material to be the pulp include wood, wheat, straw, reed, kenaf, bagasse, bamboo, bamboo grass, etc., but wood is most often used. Depending on the step of pulping, that is, the step of taking out cellulose fibers from the raw material, chemical pulp, mechanical pulp, thermo-mechanical pulp and the like can be mentioned and any of them can be used. Chemical pulp is pulp made by treating with chemicals, mechanical pulp is pulp made by beating the raw material with a beater, etc., and is typically groundwood pulp. And mechanically ground pulp. In the present invention, waste paper can also be used as a partial replacement for these new pulps.

Inorganic filler (B) used in the present invention
For the paper, a general papermaking mineral filler having a negatively charged particle surface in a papermaking stock solution is used. For example, kaolin clay, clay, titanium oxide, anionic heavy calcium carbonate, light calcium carbonate, calcined clay, wollastonite, synthetic silica, talc, aluminum hydroxide, mineral fiber, glass fiber, perlite and the like, These may be used alone or in combination of two or more. Cationic calcium carbonate or the like can be used in combination with the above-mentioned anionic particles.

The papermaking stock solution used in the present invention is a solution in which the above-mentioned cellulose fiber (A) or this and the above-mentioned inorganic filler (B) are dispersed in water. The amount of the inorganic filler (B) added is not limited, but it is preferable to add the inorganic filler (B) to the papermaking stock solution so that the content of the inorganic filler (B) in the paper of the product is 150% by weight or less with respect to the cellulose fiber. It is also possible to As long as the object of the present invention is achieved, the papermaking stock solution includes
Sizing agent, fixing agent, defoaming agent, slime control agent,
Dyes and other additives can be added. The stock solution for papermaking can be used in a pH range of 4 to 10, preferably in a pH range of 4 to 5.5 in acidic papermaking and in a pH range of 5.5 to 10 in neutral papermaking.

The polymer (C) used in the present invention is preferably cationic or amphoteric. The cationic polymer is a polymer having a cationic group in the molecule. An amphoteric polymer is a polymer having both positive and negative functional groups in the same chain of the polymer, and in general, either positive or negative (cationic or anionic) functions are dominant, but here, a functionally advantageous cationic Is dominant. Examples of the polymer as the component (C) include cationic or amphoteric starch, cationic or amphoteric polyacrylamide derivatives, cationic or amphoteric guar gum, polydimethylaminoethyl methacrylate, polyethyleneimine, polyamide-polyamine-epichlorohydrin resin and the like. These can be used alone or in combination with each other, with each other or with each other, or in combination with each other. The polymer as the component (C) is preferably a cationic or amphoteric starch, a cationic or amphoteric polyacrylamide derivative or a mixture thereof, and particularly preferably a cationic starch or a cationic polyacrylamide derivative.

The cationic starch used as the component (C) is, for example, a potato starch, corn starch, wheat starch, tapioca starch, their oxidized starch, hydrolyzed starch or the like as a raw material, and a cationizing agent such as a wet type. Method, a dry method, an organic solvent method and the like to obtain cations. Examples of the cationizing agent include quaternary ammonium chloride, quaternary ammonium sulfate, and quaternary ammonium sulfamate. The quaternary ammonium group is, for example, 3-chloro-2-hydroxypropyl-trimethylammonium. Group, 2,3-epoxypropyl-
A trimethylammonium group may be mentioned. The degree to which the starch is cationized by the cationizing agent is generally expressed by the degree of substitution, which is determined by the ratio of the number of glucose units of the starch molecule to the number of quaternary ammonium groups substituted by ether bonds. Is defined. Examples of preferable cationized starch used in the present invention include those having a substitution degree of 0.01 to 0.05, and commercially available cationized starch can be used. The above cationic starch can be converted to an amphoteric starch by anionization by further introducing a functional group such as carboxymethyl, sulfonic acid, and phosphonic acid into a quaternary amine.

The cationic or amphoteric polyacrylamide derivative used as the component (C) is prepared from a water-soluble polymer prepared by a conventional polymerization method, and is converted to an amide group (--CONH).
Cation of ₂ ) using Mannich reaction or Hoffmann reaction, anionization by carboxylation or sulfomethylation reaction by partial hydrolysis, or copolymerization of sodium vinyl sulfonate and acrylamide or acrylic acid and acrylamide. Is used as an anionic polyacrylamide derivative, or a copolymer of acrylamide and a cationic monomer having a secondary, tertiary or quaternary amino group such as dimethylaminoethyl methacrylate is used as a cationic polyacrylamide derivative. It is possible to obtain an amphoteric polyacrylamide derivative or a cationic polyacrylamide derivative by combining the two by cationization by the method described above. The degree of substitution of the cationic group is at least 0.01, preferably 0.03 or more, but 0.05 to 0.
5 is more preferable. The molecular weight of the polyacrylamide derivative is 2 million or less, preferably 1.5 million or less, and more preferably 100,000 to 1.3 million.

The component (C) is, in addition to a cationic or amphoteric starch, a cationic or amphoteric polyacrylic amide derivative, a cationic or amphoteric guar gum, polydimethylaminoethyl methacrylate, polyethyleneimine, polyamide-polyamine- Epichlorohydrin resin can be used. Guar gum is
Annual legume plant Siamopsis-tetragonalops (Cymo) growing in India, Pakistan, Texas, USA, etc.
This is a galactomannan gum extracted from the endosperm of seeds of psi-tetragonolobus). In the guar gum molecule, the main chain is mannan and the D-mannopyranose unit is β (1 → 4) -bonded, and the monosaccharide D-galactopyranose is α- (1 → 6) -bonded to the bone nucleus. The cationic derivative is formed by reacting the hydroxyl group of polygalactomannan with a reactive quaternary ammonium compound.
The above-mentioned cationized guar gum and amphoteric guar gum obtained by combining cationization and anionization can be obtained by carrying out a cationization reaction and an anionization reaction similarly to starch. The degree of substitution is defined by the ratio of the number of quaternary ammonium groups substituted by ether bonds to the number of mannose and galactose units of the guar gum molecule. The degree of cationic substitution is at least 0.01, preferably 0.08-0.5. The molecular weight of guar gum is 100,000 to 1,000,000, and preferably 200,000 to 300,000.

Polydimethylaminoethyl methacrylate exhibits a cationic property due to a tertiary amino group. Polyethyleneimine in the molecule (-CH ₂ CH ₂ NH-)
It has a bond of 1 and shows a cationic property due to a secondary amino group. Polyethyleneimine can be obtained, for example, by ring-opening polymerization of ethyleneimine or polycondensation reaction of ethylene chloride and ethylenediamine.

Polyamide-polyamine-epichlorohydrin resin (PPE) is obtained, for example, by subjecting adipic acid and diethylenetriamine to a polycondensation reaction to form an acid amide bond (-C).
It is obtained by synthesizing a polyamide-polyamine chain by the formation of ONH-), carrying out an addition reaction between the amino group of this polyamide-polyamine intermediate and epichlorohydrin, and then performing a dehydrochlorination reaction. This polyamide-polyamine-epichlorohydrin resin is a polyamide-polyamine having a glycidyl group in the molecule. The polyamide-polyamine-epichlorohydrin resin has a secondary amino group having a cationic property and a tertiary amino group in the molecule.

The product obtained by reacting the sulfonated amino resin of the component (D) used in the present invention with the amino group-containing substance is a product obtained by reacting the sulfonated amino resin and the amino group-containing substance in the range of 1: 0.05-. A product obtained by reacting in a weight ratio of 3. As the sulfonated amino resin used for the synthesis of the component (D), a sulfonate-containing melamine-formaldehyde condensate can be preferably used. The sulfonate is an alkali metal salt, and the sodium salt is particularly preferable. As the sulfonate-containing melamine-formaldehyde condensate, a commercially available aqueous solution can be used. As the sulfonate-containing melamine-formaldehyde condensate aqueous solution, any one produced by a known method can be used. For example, Japanese Patent Fair 2
No. 43763 discloses an amino group-containing substance containing melamine as a main component, formaldehyde of 0.9 to 1.1 mol and sulfite of 0.3 to 0.4 mol per mol of amino group, and pH of 10 in an aqueous medium. ~ 13, temperature 60 ~ 80 ℃ 20
After reacting by heating for ~ 60 minutes, amidosulfonic acid and / or sulfuric acid is added to the reaction mixture to adjust the pH to 4-6, and the mixture is heated at 40-60 ° C for 50-300 minutes and immediately pH adjusted.
Is adjusted to 11.5 to 13.5 and then cooled, and a method for producing a high-concentration sulfonate-containing melamine-formaldehyde condensate aqueous solution is described. The sulfonate-containing melamine-formaldehyde condensate aqueous solution obtained by this method is used. It can be used for the synthesis of the component (D). In this method, the amino group-containing substance containing melamine as a main component is melamine alone or melamine and an amino group-containing compound in a proportion of 20% by weight or less, for example, urea, guanamines,
It is a mixture with dicyandiamide, amine, acid amide, phenol, resorcin, and the like. Formaldehyde is formalin, paraformaldehyde, etc., and sulfites are sodium sulfite, ammonium sulfite, sodium bisulfite, ammonium bisulfite, sodium pyrosulfite, etc. It is done. Although the molecular weight of this sulfonated amino resin is not particularly limited, it may be from 2000 to 20.
0000 is preferred. The amino group-containing substance used in the synthesis of the component (D) can be used alone or as a mixture of melamine and urea, guanamines, dicyandiamide, amine, acid amide, phenol, resorcin, and the like. In particular, it is preferable to use melamine (C ₃ H ₆ N ₆ ) alone. The above melamine can be used in the form of a commercially available powder.

The method for producing the product obtained by reacting the sulfonated amino resin as the component (D) with the amino group-containing substance is as follows. Mixing to the solid content weight ratio of
It consists of heating to a temperature of 50 to 150 ° C. In the above production method, there are a method of pre-mixing the sulfonated amino resin aqueous solution and the amino group-containing substance and then heating, and a method of adding the amino group-containing substance to the heated sulfonated amino resin aqueous solution. In order to prevent the condensation reaction between amino resins, it is more preferable to premix the sulfonated amino resin aqueous solution and the amino group-containing substance and then heat the mixture. In this reaction, by heating to the above temperature, a dehydration reaction occurs between the methylol group or sulfone group in the sulfonated amino resin and the amino group of the amino group-containing substance, and the condensation reaction proceeds to produce a condensation product. Is what you get. The above reaction is a mineral acid such as sulfuric acid or hydrochloric acid,
The condensation reaction proceeds efficiently by adding sulfamic acid and an organic acid such as formic acid and acetic acid as a catalyst. The above catalyst is preferably added so that the pH of the aqueous liquid containing the sulfonated amino resin and the amino group-containing substance is 5-10. In addition, since the alkali salts of sulfuric acid and sulfamic acid are generally present in sulfonated amino resins, the pH can be adjusted by cation exchange of this alkali.
Can be 5-10.

In the present invention, a solution prepared by further adding a catalyst such as sulfuric acid to a solution consisting of an aqueous sulfonated amino resin solution and an amino group-containing substance is heated at a temperature of 50 to 150 ° C. for 5 to 6 hours, and then diluted with water and alkali. It can be manufactured by stabilizing by adding a substance. In addition, a solution containing a sulfonated amino resin aqueous solution and an amino group-containing substance was added to
After heating to a temperature of up to 150 ° C., a catalyst such as sulfuric acid is added and heated for 5 to 6 hours, followed by dilution with water and stabilization by the addition of an alkaline substance to produce the product.

The product obtained by reacting the sulfonated amino resin and the amino group-containing substance in the component (D) is
It is 1: 0.05 to 3 in terms of the weight ratio of the sulfonated amino resin and the amino group-containing substance. The weight ratio of the above products can be measured by elemental analysis. When the ratio of the amino group-containing substance to the sulfonated amino resin exceeds 3, a product is formed, but excessive precipitation of the amino group-containing substance occurs, which is not preferable. On the other hand, if it is less than 0.05, the amount of product produced is small, which is not preferable. Above (D)
In the production of the product obtained by reacting the sulfonated amino resin as a component with the amino group-containing substance, the concentration of the mixture of the sulfonated amino resin aqueous solution and the amino group-containing substance is 1
It can be used as up to 50% by weight. If it is less than 1% by weight, the production efficiency is lowered, which is not preferable. If it exceeds 50% by weight, the viscosity of the obtained liquid becomes too high, which is not preferable. 5-20% by weight is particularly preferred.

The reaction temperature at the time of obtaining the condensation product of the component (D) from a liquid obtained by mixing the sulfonated amino resin aqueous solution and the amino group-containing substance is preferably 50 to 150 ° C. When the reaction is carried out at a temperature above the boiling point of the aqueous medium, it can be carried out using an autoclave device. If the reaction temperature is less than 50 ° C, the production of the product is insufficient, which is not preferable. Also 150
A product can be formed even if the temperature exceeds ℃, but the reaction is difficult to control, which is not preferable. 60-100 degreeC is especially preferable. The reaction time for producing this product varies depending on the reaction temperature, but is 10 minutes to 20 hours. 10
If it is less than a minute, the production of the product is insufficient, and the reaction can be completed in 20 hours, and if it is longer than that, it is not economical.

In the component (D), a solution prepared by mixing the sulfonated amino resin aqueous solution and the amino group-containing substance is added in an amount of 50 to 15
It is also possible to add a sulfonated amino resin aqueous solution or an amino group-containing substance to a liquid containing the product obtained by heating at 0 ° C, and heat at 50 to 150 ° C. The product obtained by reacting the sulfonated amino resin as the component (D) with the amino group-containing substance is basically a colloidal substance having particle properties, and the solution of the product obtained as the component (D) is a colloid. It can be called a solution (sol). The colloidal particles of this product have a primary particle size of 1 to 100 nm (nanometers), and since they exist alone or in the form of aggregates, the colloidal solution of the product changes from transparent to transparent colloidal color. There is even something to present. In the present invention (D)
The component can be used as a sol in which particles obtained by reacting a sulfonated amino resin with an amino group-containing substance and having a primary particle diameter of 1 to 100 nm are dispersed in a liquid medium. . The above liquid medium is preferably an aqueous medium. Here, the primary particle diameter is not the diameter of particles in an aggregated form but the diameter of one particle when they are individually separated, and can be measured by electron microscope observation. The primary particles aggregate to form an aggregate. The particle size of this aggregate is determined by the dynamic light scattering method, and can be measured, for example, by a Coulter N ₄ apparatus. The viscosity of a colloidal solution of this product is 1.5 to 10,000 mPa · S in a 10% by weight solution of the product.
And shows a gelation phenomenon due to being a colloidal solution.

The colloid of the product obtained by reacting the sulfonated amino resin as the component (D) with the amino group-containing substance has a negative charge due to the sulfone group, but has a cation site due to the amino group. Therefore, it can be said that they are basically bisexual. The zeta potential is 0 to -60 mV. The pH can be adjusted to 7 to 12 by adding an alkali metal hydroxide, sodium aluminate, sodium silicate, ammonia, amine or the like to the solution of the product obtained as the component (D). Further, the free formaldehyde present in the aqueous solution of the sulfonated amino resin due to the heating during the reaction reacts with the amino group-containing substance to become the amino resin, so that in the product solution obtained as the component (D), Free formaldehyde is virtually absent.

The solution of the product obtained by reacting the sulfonated amino resin as the component (D) and the amino group-containing substance can be concentrated by a method such as an evaporation method or an ultrafiltration method, if necessary. In particular, the ultrafiltration method can simultaneously remove salts such as sodium sulfate in the solution. Further, this solution can be made into a dry powder by using a spray dryer, a drum dryer or the like. By redispersing the dry powder in water, particles of the product obtained as the component (D) described above become a colloidal solution (sol) in which water is dispersed.

Generally, the sulfonated amino resin aqueous solution is stabilized with caustic soda. Also in the component (D), the solution of the product obtained by reacting the sulfonated amino resin and the amino group-containing substance is stabilized with caustic soda, but this solution was exchanged with cations such as ammonia, amine, and calcium. By passing the solution through a column packed with an ion exchange resin, a solution of the component (D) stabilized with ammonia, amine, calcium or the like can be obtained. In the solution of the component (D), a surfactant such as naphthalene sulfonate, lignin sulfonate, alkylbenzene sulfonate, silica sol, bentonite, anionic polymer such as anionic polyacrylamide, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, etc. The water-soluble polymer can be mixed.

In the paper making method of the present invention, the above-mentioned cationic or amphoteric polymer (C) is used to improve the yield, drainage, productivity and paper strength, texture and paper quality of the product.
And a product (D) obtained by reacting a sulfonated amino resin with an amino group-containing substance in a specific ratio to a papermaking stock solution. When adding to the papermaking stock solution,
The above-mentioned components (C) and (D) can be added as a solid or an aqueous solution. The concentration of the aqueous solution is not particularly limited.

The yield-improving ratio is preferably 100% by weight or less, and particularly preferably 1 to 50% by weight, of the component (D) with respect to the cationic or amphoteric polymer (C). Further, the amount of the above-mentioned component (D) (solid content) with respect to the amount (solid content) of the cellulose fiber in the papermaking stock solution or the total amount (solid content) of the cellulose fiber and the inorganic filler.
Is 0.01 to 2.0% by weight. Then, the addition amount (solid content) of the component (C) is 0.01 to 5 relative to the amount (solid content) of the cellulose fibers in the papermaking stock solution or the total amount (solid content) of the cellulose fibers and the inorganic filler. It is 0.0% by weight.

In the present invention, the product (D) obtained by reacting the cationic or amphoteric polymer (C) with the sulfonated amino resin and the amino group-containing substance can be added to the papermaking stock solution first. . As long as the object of the present invention is achieved, when adding the above-mentioned cationic or amphoteric polymer (C) to the papermaking stock solution, other cationic substances, for example,
Alumina sol, basic aluminum chloride, cationic silica sol, aluminum sulfate, basic aluminum sulfate and the like can be added.

After the cationic or amphoteric polymer (C) according to the present invention and the product (D) obtained by reacting the sulfonated amino resin and the amino group-containing substance with each other are thoroughly mixed, It is supplied to a paper machine by a usual method, and the wet sheet thus obtained is subjected to a dehydration step and a drying step to produce a product paper. Since the cellulose fiber and the inorganic filler in the papermaking stock solution have a negative charge, the cationic or amphoteric polymer alone is strongly adsorbed on the surface of the cellulose fiber and the inorganic filler,
By forming an agglomerate composed of a cellulose fiber and an inorganic filler and a cationic or amphoteric polymer, it is possible to improve the drainage property at the time of papermaking, the yield and the paper strength and texture of the produced paper. However, cellulose fibers and inorganic fillers have a small negative charge, and because the particle size is larger than polymers, the cohesive force of the agglomerates generated is weak and they are easily broken by a strong mechanical shearing force, so they are sufficient for actual production. Yield, drainage and productivity are not improved.

Usually, in a dual polymer system using a cationic polymer and an anionic polymer, a very strong aggregate is formed by further adding an anionic polymer having a large negative charge to the aggregate formed by the cationic polymer, Drainage, yield, productivity and paper quality have been improved. The papermaking method of the present invention is also a kind of this dual polymer system, and it can be said that the mechanism of action is the same as that of a normal dual polymer system.

However, the present invention is characterized in that the anionic polymer is a product (D) obtained by reacting a sulfonated amino resin with an amino group-containing substance. Generally, a sulfonated amino resin has an average molecular weight of 2000 to 200,000, is two-dimensionally polycondensed, is negatively charged by a sulfone group, and is usually obtained as a colorless and transparent polymer aqueous solution. To this sulfonated amino resin aqueous solution, an amino group-containing substance having a small solubility in water such as melamine is added to have a solubility or higher,
Surprisingly, the amino group-containing substance dissolves by heating, and the amino group-containing substance does not precipitate even when cooled. This cannot be explained simply by the fact that the positively charged amino group-containing substance is adsorbed on the negatively charged sulfonated amino resin surface. This is a product obtained by depolymerizing the sulfonated amino resin by heating in the presence of the amino group-containing substance, chemically bonding with the amino group-containing substance, and reacting the sulfonated amino resin with the amino group-containing substance. It should be considered that the thing (D) is formed. That is, a dehydration reaction occurs between the methylol group (—CH ₂ OH) or sulfone group (—SO ₃ H) in the sulfonated amino resin and the amino group (—NH ₂ ) of the amino group-containing substance, and a chemical bond is formed. It is considered to be formed. 3 if the amino group-containing substance has two or more amino groups
A product (D) of the sulfonated amino resin and the amino group-containing substance extending in the dimension is formed. Therefore, this product is basically a colloidal substance having a particle property, and the solution of the obtained product can be called a colloidal solution (sol). The component (D) has a primary particle diameter of 1 to 100 nm.
The average particle size in the liquid by the dynamic light scattering method is 5 to 500 n
m is a colloid and shows a negative charge as a whole, but it has a strong anion site due to a sulfone group and a weak cation site due to an amino group, and thus has an amphoteric property. Cellulose fibers (A), inorganic fillers (B), cationic or amphoteric polymers (C), which strongly adsorb to anionic cellulose fibers and inorganic fillers and cationic or amphoteric polymers, A good agglomerate of the product (D) obtained by reacting the sulfonated amino resin with the amino group-containing substance is formed.

Such an action is not found in conventional anionic polymers. For example, a conventional sulfonate-containing melamine-formaldehyde condensate (SM
F) is a linear water-soluble polymer, which is dissolved in water. On the other hand, the product (D) obtained by reacting the sulfonated amino resin used in the present invention with the amino group-containing substance is
By combining a sulfonated amino resin oligomer having a negative site with a substance having an amino group such as melamine having a positive site, a micro-aggregate having a colloidal particle size is formed. Above (D)
The solution of the components is a stable colloidal solution (sol), but when the solution of the above product is added to the papermaking process from pulp slurry containing cellulose fiber, inorganic filler and ionic polymer, the product Has a cation site and an anion site, and has a large specific surface area to be adsorbed to an ionic component in the pulp slurry to exhibit remarkable cohesiveness to form flocs, which makes it an excellent yield improver. Compared with the conventional sulfonate-containing melamine-formaldehyde condensate dissolved in water, the use of the colloidal state (D) used in the present invention facilitates the formation of flocs. ) Is extremely useful as an additive for papermaking.

Therefore, in the papermaking method of the present invention, by selecting a cationic or amphoteric polymer, a good yield, drainage, productivity improvement and paper strength of the produced paper can be obtained in a wide range from acidic papermaking to neutral papermaking. It is extremely effective for quality improvement such as formation.

[0035]

EXAMPLE As a product (D) obtained by reacting a sulfonated amino resin with an amino group-containing substance, the following (D1)
~ (D5) were prepared. (Production Example of D1) Sulfonated amino resin aqueous solution prepared by a known method in a 2-liter four-necked flask equipped with a reflux condenser, a stirrer and a thermometer [sodium sulfonate-containing melamine-formaldehyde condensate aqueous solution, Specific gravity 1.214 (measured at 20 ° C), pH 8.50, viscosity 2
3.9 mPa · S (measured at 20 ° C), conductivity 31.00
mS / cm, sulfonated amino resin solids content 32.9% by weight (14.4% by weight as melamine), formaldehyde / sulfonic acid molar ratio 3.6, free formaldehyde (measured by titration method) 0.7% by weight, It is a colorless transparent liquid having a formaldehyde / melamine molar ratio of 3.50, an average molecular weight of 15,000, and a transmittance (L value) of 99.8%. ] 200g
(Including 65.8 g of sulfonated amino resin) and 690 g of pure water were added, 3.5 g of 10% sulfuric acid was added with stirring, and then 39.0 g of melamine (manufactured by Nissan Chemical Industries, Ltd.).
Was added. The total solid content of the resin of the mixed liquid of the sulfonated amino resin and melamine was 11.2% by weight, the weight ratio of melamine / sulfonated amino resin was 0.593, and the pH was 7.
It was 50. This mixed solution was heated to react at 98 ° C. for 2 hours and then cooled to obtain 932.5 g of a solution of the product (D1) obtained by reacting the sulfonated amino resin and melamine. By heating, the above-mentioned mixed solution completely melted melamine at 80 to 90 ° C., and became a transparent solution. By continuing heating, the mixed solution exhibited a colloidal color.

The resulting product (D1) solution had a specific gravity of 1.056 (measured at 25 ° C.), a pH of 8.13 and a viscosity of 2.
4 mPa · S (measured at 25 ° C.), solid content of product 11.
2% by weight, melamine / sulfonated amino resin weight ratio 0.593, formaldehyde / sulfonic acid molar ratio 3.6, formaldehyde / melamine molar ratio 1.4.
9. Average particle size by dynamic light scattering method (manufactured by Coulter,
Measured by Coulter N ₄ ] 16.1 nm, the zeta potential was -10 mV, and the solution was transparent with a slight colloidal color. Particles were observed by electron microscope observation, and the primary particle diameter was 5 to 10 nm. Further, free formaldehyde was not detected by the titration method in this solution, and it was stable at room temperature for 6 months or more.

(Production Example of D2) A 2-liter four-necked flask equipped with a reflux condenser, a stirrer and a thermometer was used (D2).
Sulfonated amino resin aqueous solution [sodium sulfonate-containing melamine-formaldehyde condensate aqueous solution] used in Production Example 1) 120 g (3 as sulfonated amino resin
Contains 9.5 g. ), 615 g of pure water was added, 4.3 g of 10% sulfuric acid was added with stirring, and then 21.4 g of melamine [manufactured by Nissan Chemical Industries, Ltd.] was added. The total solid content of the resin in the mixed solution of the sulfonated amino resin and melamine was 8.0% by weight, the weight ratio of melamine / sulfonated amino resin was 0.542, and the pH was 6.75. This mixed solution was heated at 98 ° C. for 2.5 hours to react. The solution of the obtained product (D2) had a colloidal color. Furthermore (D
36 g (containing 11.8 g of sulfonated amino resin) of the sulfonated amino resin aqueous solution used in the production example of 1) was added and reacted at 98 ° C. for 3.5 hours, and then 2.6 g of 10% aqueous sodium hydroxide solution was added. After heating at 98 ° C. for 10 minutes and then cooling, 920.7 g of a solution of the product (D2) obtained by reacting the sulfonated amino resin with melamine was obtained.

The product (D2) solution obtained had a specific gravity of 1.039 (measured at 25 ° C.), a pH of 9.62 and a viscosity of 5.
2 mPa · S (measured at 25 ° C), conductivity 13.30 mS
/ Cm, solid content of the product 7.90% by weight, melamine / sulfonated amino resin weight ratio 0.417, formaldehyde / sulfonic acid molar ratio 3.6, formaldehyde /
Melamine molar ratio 1.79, average particle size 103 nm by dynamic light scattering method, zeta potential minus 12
It had a mV and a transmittance (L value) of 86.7%, no free formaldehyde was detected by the titration method, and the solution was colloidal and highly transparent. Particles were observed by electron microscope observation, and the primary particle diameter was 5 to 10 nm. The solution was stable at room temperature for 6 months or more.

(Production Example of D3) In a 2-liter four-necked flask equipped with a reflux condenser, a stirrer and a thermometer (D3)
Sulfonated amino resin aqueous solution [sodium sulfonate-containing melamine-formaldehyde condensate aqueous solution] used in Production Example 1) 200 g (6 as sulfonated amino resin)
Contains 5.8 g. ), 589 g of pure water was added, 4.0 g of 10% sulfuric acid was added with stirring, and then 39.0 g of melamine [manufactured by Nissan Chemical Industries, Ltd.] was added. The total solid content of the resin in the mixed liquid of the sulfonated amino resin and melamine was 12.6% by weight, the weight ratio of melamine / sulfonated amino resin was 0.593, and the pH was 7.31. After heating this mixed solution for 2 hours at 98 ° C., 2 g of 10% caustic soda and 40 g of the sulfonated amino resin aqueous solution used in the production example of (D1) (13.2 g as sulfonated amino resin are contained). ) Is added, and further at 98 ° C. for 1.5
912 g of a solution of the product (D3) obtained by reacting the sulfonated amino resin with melamine after reacting for a time
I got

The product (D3) solution obtained had a specific gravity of 1.067 (measured at 25 ° C.), a pH of 8.79 and a viscosity of 2.
6 mPa · S (measured at 25 ° C), conductivity 17.90 mS
/ Cm, product solids 12.9% by weight, melamine / sulfonated amino resin weight ratio 0.494, formaldehyde / sulfonic acid molar ratio 3.6, formaldehyde /
Melamine molar ratio 1.64, average particle size 16.3 nm by dynamic light scattering method, zeta potential minus 1.
At 2 mV and a transmittance (L value) of 96.9%, no free formaldehyde was detected by the titration method, and the solution was a clear solution showing a slight colloidal color. Particles were observed by electron microscope observation, and the primary particle diameter was 5 to 10 nm.
This solution was stable at room temperature for 6 months or more.

(Production Example of D4) A 2-liter four-necked flask equipped with a reflux condenser, a stirrer and a thermometer was used (D4).
Sulfonated amino resin aqueous solution [sodium sulfonate-containing melamine-formaldehyde condensate aqueous solution] used in Production Example 1) 600 g (1 as sulfonated amino resin
(Including 97.4 g) and 1200 g of pure water were added, 24 g of 10% sulfuric acid was added with stirring, and then 81 g of melamine [manufactured by Nissan Chemical Industries, Ltd.] was added. The total solid content of the resin and melamine in the mixed liquid of the sulfonated amino resin and melamine was 14.6% by weight, the weight ratio of melamine / sulfonated amino resin was 0.41, and the pH was 6.83. This mixture was heated and reacted at 92 ° C. for 6 hours, then 960 g of pure water was added and then cooled, and a 10 wt% NaOH aqueous solution 16 was further added.
g was added to obtain 2881 g of a solution of the product (D4) obtained by reacting the sulfonated amino resin with melamine. By heating, the above-mentioned mixed solution completely melted melamine at 80 to 90 ° C., and became a transparent solution. By continuing heating, the mixed solution exhibited a colloidal color. The resulting solution of product (D4) is
Specific gravity 1.044 (measured at 25 ° C), pH 10.38, viscosity 65 mPa · S (measured at 25 ° C), solid content of product 1
0.0% by weight, melamine / sulfonated amino resin weight ratio 0.41, formaldehyde / sulfonic acid molar ratio 3.6, formaldehyde / melamine molar ratio 1.8.
1. Average particle size by dynamic light scattering method (manufactured by Coulter,
Measurement with Coulter N ₄ ] 179 nm, zeta potential was -10 mV, and the solution was a transparent solution with a slight colloidal color. Particles were observed by electron microscope observation, and the primary particle diameter was 5 to 10 nm. Further, free formaldehyde was not detected by the titration method in this solution, and it was stable at room temperature for 6 months or more.

(Production Example of D5) A 2-liter four-necked flask equipped with a reflux condenser, a stirrer and a thermometer was used (D5).
Sulfonated amino resin aqueous solution [sodium sulfonate-containing melamine-formaldehyde condensate aqueous solution] used in Production Example 1) 600 g (1 as sulfonated amino resin
(Including 97.4 g) and 1000 g of pure water were added, 24 g of 10% sulfuric acid was added with stirring, and then 69 g of melamine [manufactured by Nissan Chemical Industries, Ltd.] was added. The total solid content of the resin and melamine in the mixed liquid of the sulfonated amino resin and melamine was 15.7% by weight, the weight ratio of melamine / sulfonated amino resin was 1.40, and the pH was 6.65. This solution was heated and reacted at 93 ° C. for 7 hours, then 1083 g of pure water heated to 48 ° C. was added and kept at 82 ° C. for 1 hour and then cooled, and at 60 ° C., 14 g of 10% NaOH aqueous solution was added and then cooled. 2790 g of a solution of the product (D5) obtained by reacting the sulfonated amino resin with melamine was obtained. By heating, the above-mentioned mixed solution completely melted melamine at 80 to 90 ° C., and became a transparent solution. By continuing heating, the mixed solution exhibited a colloidal color.

The product (D5) solution thus obtained had a specific gravity of 1.042 (measured at 25 ° C.), a pH of 9.73 and a viscosity of 1.
7.8 mPa · S (measured at 25 ° C.), solid content of product 1
0.0% by weight, melamine / sulfonated amino resin weight ratio 1.40, formaldehyde / sulfonic acid molar ratio 3.6, formaldehyde / melamine molar ratio 1.9.
5. Average particle size by dynamic light scattering method (manufactured by Coulter,
Measurement with Coulter N ₄ ] 135 nm, zeta potential was -12 mV, and the solution was a clear solution with a slight colloidal color. Particles were observed by electron microscope observation, and the primary particle diameter was 5 to 10 nm. Further, free formaldehyde was not detected by the titration method in this solution, and it was stable at room temperature for 6 months or more.

Example 1 (i) Preparation of pulp slurry As a cellulose fiber (A), a softwood bleached kraft dry pulp (A1) and a hardwood bleached kraft dry pulp (A2)
Prepared. Conifer bleached craft dry pulp (A1) 9
0g and 270g of hardwood bleached craft dry pulp (A2)
Was added to 25 kg of water and left for one day and night.
The pulp slurry was adjusted by beating so as to have a volume of 50 ml. (Ii) Preparation of stock solution for papermaking Heavy calcium carbonate (B1) as inorganic filler (B),
An aluminum sulfate aqueous solution (B2), kaolin (China clay: B3), and a rosin sizing agent (E1) as an organic filler were prepared.

Heavy calcium carbonate (B1), water and sulfuric acid were added to the above-mentioned pulp (A1 + A2) slurry,
A neutral papermaking stock solution (α) having a pulp concentration of 0.35% by weight, a heavy calcium carbonate concentration of 0.15% by weight and a pH of 7.1 was prepared. Aluminum sulphate aqueous solution (B2), kaolin (China clay: B) is added to the above pulp (A1 + A2) slurry.
3), rosin sizing agent (E1), water and sulfuric acid are added, and the pulp concentration is 0.35% by weight, kaolin 0.15% by weight, aluminum sulfate (18 hydrate) 0.0035% by weight, rosin sizing agent 0.0015. A papermaking stock solution (β) having a weight% of kaolin / pulp of 0.43 and a pH of 4.5 was prepared. (Iii) Preparation of Cationic Polymer (C) Aqueous Solution As the cationic polymer (C), the following cationized starch (C1) and cationic polyacrylamide (C) were used.
2) was prepared.

0.5% by weight of cationized cationized starch (C1) using potato as a raw material starch
An aqueous solution was prepared. The cationized starch (C1) had a nitrogen content of 0.35% and a degree of substitution of 0.042. Cationic polyacrylamide (C2) for agglomerating stock, which is commercially available in a slurry having an effective concentration of 15% by weight, was used as an aqueous solution prepared by diluting with pure water to adjust the effective component concentration to 0.5% by weight. (Iv) Addition method After preparing a slurry of beaten pulp (A1 + A2), heavy calcium carbonate (B1), aluminum sulfate aqueous solution (B2), kaolin (China clay: B3), and optionally rosin sizing agent (E1). ) Is added to prepare an acidic to neutral papermaking stock solution, and a cooking solution of potato cationized starch (C1) cationized with quaternary ammonium chloride is further prepared.
A cationic polyacrylamide (C2) aqueous solution and a solution of a product obtained by reacting the sulfonated amino resin prepared in the above Production Examples (D1) to (D5) with an amino group-containing substance were added, and then papermaking was performed to obtain a fine paper. The yield of the components was measured. (V) Measurement Method of Yield of Fine Component Yield measurement is described in Tappi magazine as a dynamic drainage jar test method (also referred to as Britt-Jar test method) (Br).
itt. K. W. : Tappi, 56 (10). 46-
50, 1973) according to the following procedure.

Total concentration G weight% of pulp (A1 + A2) and inorganic fillers (B1) to (B3) in the papermaking stock solution
Is calculated accurately. By adding a surfactant to the papermaking stock solution so that the fine components can easily pass through the papermaking stock solution and then passing through a 200-mesh wire net, the weight of the components that did not pass through the papermaking stock solution was measured. The ratio F% by weight of the total fine components passing through the wire net to the total of pulp and filler is calculated. The concentration of all fine components in the papermaking stock solution is calculated as G × F / 100% by weight.

-1) 500 ml of the papermaking stock solution was put into a jar and stirred at a speed of 800 rpm,
Time measurement was started, and 15 seconds later, a cationized starch (C1) cooking liquid (starch concentration: 0.5% by weight)
A predetermined amount of the solution, and a solution of the products (D1) to (D3) obtained by reacting the sulfonated amino resin prepared in Production Example with the amino group-containing substance 30 seconds after the start of the measurement (resin concentration 0.5% by weight). ) Is added in a predetermined amount, and when 45 seconds have elapsed from the start of timing, drainage is started and white water is collected for 30 seconds. Measure the volume of the collected white water to Y milliliter. Use a wire mesh of 200 mesh, and adjust the diameter of the drainage port so that the drainage volume for 30 seconds is about 10
It was set to 0 ml.

-2) 500 ml of the stock solution for papermaking was put into a jar and stirred at a speed of 1000 rpm, and then time measurement was started. After 15 seconds, 0.5% by weight aqueous solution of the cationic polyacrylamide (C2) was added. A solution of products (D4) to (D5) (resin concentration 0.5% by weight) obtained by adding a predetermined amount and reacting the sulfonated amino resin prepared in the production example with the amino group-containing substance after 45 seconds from the start of timing. Is added in a predetermined amount, and when 60 seconds have elapsed from the start of timing, drainage is started and white water is collected for 30 seconds. Measure the volume of the collected white water to Y milliliter. It should be noted that a wire mesh of 200 mesh was used, and the drainage amount for 30 seconds was adjusted to about 100 ml by adjusting the diameter of the drainage port.

A filter paper for quantification having a dry weight of W ₁ g is prepared, the white water collected in is filtered with this filter paper, the filter paper is dried and then weighed to obtain W ₂ g. W ₂ -W ₁ represents the weight of the fine components in the white water Y milliliters which has passed through the wire mesh. The ratio of the fine components retained on the wire mesh to the total fine components in the papermaking stock solution, that is, the yield Z (%) of the fine components is Z = ((G × F) − (10000 (W ₂ −W ₁ ) /
Y)) ÷ (G × F) × 100.

(Vi) Yield Measurement of Fine Components and Results The ratio F of all fine components in the papermaking stock solution prepared in (ii) above was 35% by weight. The stock solution itself had a fine component yield of 13.5% by weight. A1, A2, B1, B2, B3, C1, C at the ratios shown in Table 1
The yield (%) of the fine component was measured by adding 2, D1, D2, and D3. Table 1 shows the results. In Table 1, the addition amount (solid content) of the cationized starch (C1) and the cationic polyacrylamide (C2) is the total amount (solid content) of the cellulose fibers (A1), (A2) and the inorganic filler (B). % By weight. Further, the addition amount (solid content) of the products (D1) to (D5) obtained by reacting the sulfonated amino resin and the amino group-containing substance is determined by the cellulose fibers (A1), (A2) and the inorganic filler (B). Is shown in weight% with respect to the total amount (solid content). Similarly, the yields (%) of the fine components of Examples 2 to 21 were measured.

[0052]

[Table 1] Table 1 Example Papermaking stock solution pH C type C addition amount D type D addition amount Yield 1 α 7.1 C1 1.0 D1 0.1 72.5 2 α 7.1 C1 1.0 D1 0.2 86.0 3 α 7.1 C1 1.0 D1 0.3 90.0 4 α 7.1 C1 1.0 D2 0.1 69.0 5 α 7.1 C1 1.0 D2 0.2 84.5 6 α 7.1 C1 1.0 D2 0.3 91.0 7 α 7.1 C1 1.0 D3 0.1 78.0 8 α 7.1 C1 1.0 D3 0.2 88.4 9 α 7.1 C1 1.0 D3 0.3 92.0 10 α 7.1 C1 1.0 D4 0.1 70.5 11 α 7.1 C1 1.0 D4 0.2 84.6 12 α 7.1 C1 1.0 D4 0.3 95.6 13 α 7.1 C1 1.0 D5 0.1 71.6 14 α 7.1 C1 1.0 D5 0.2 87.3 15 α 7.1 C1 1.0 D5 0.3 95.5 16 α 7.1 C2 0.08 D4 0.02 81.3 17 α 7.1 C2 0.08 D4 0.04 91.5 18 α 7.1 C2 0.08 D4 0.08 93.9 19 β 4.5 C2 0.08 D4 0.02 52.0 20 β 4.5 C2 0.08 D4 0.04 63.5 21 β 4.5 C2 0.08 D4 0.08 71.2 Comparative Examples 1-9 Comparison Example 1 is a papermaking stock solution In the case where the products (D1) to (D5) obtained by reacting the sulfonated amino resin with the amino group-containing substance in the method of Example 1 above are not added, , And Comparative Examples 5 to
9, instead of the products (D1) to (D5) obtained by reacting a sulfonated amino resin with an amino group-containing substance, an aqueous solution of a sulfonated amino resin [an aqueous solution of a sodium sulfonate-containing melamine-formaldehyde condensate (SMF), Specific gravity 1.214 (measured at 20 ° C), pH 8.50, viscosity 2
3.9 mPa · S (measured at 20 ° C), conductivity 31.00
mS / cm, sulfonated amino resin solids content 32.9% by weight (14.4% by weight as melamine), formaldehyde / sulfonic acid molar ratio 3.6, free formaldehyde (measured by titration method) 0.7% by weight, It is a colorless transparent liquid having a formaldehyde / melamine molar ratio of 3.50, an average molecular weight of 15,000, and a transmittance (L value) of 99.8%. ], The yield (%) of the fine component was measured.
The results are shown in Table 2. In Table 2, the addition amount (solid content) of the sodium sulfonate-containing melamine-formaldehyde condensate (SMF) is the cellulose fiber (A1), (A).
2) and the total amount of the inorganic filler (B) (solid content).

[0053]

[Table 2] Table 2 Comparative example Papermaking stock solution Type of pH C Addition amount of C Addition amount of SMF Yield 1 α 7.1 − 0 0 13.5 2 α 7.1 C1 1.0 0 38.0 3 α 7.1 C2 0.08 0 46.0 4 β 4.5 C2 0.08 0 23.0 5 β 4.5 C2 0.08 0.03 24.5 6 β 4.5 C2 0.08 0.3 25.2 7 α 7.1 C1 1.0 0.1 48.0 8 α 7.1 C1 1.0 0.2 51.5 9 α 7.1 C1 1.0 0.3 49.0 (vii) Drainage measurement and its results Above (ii) By diluting the papermaking stock solution (α) prepared in 1. with water, a papermaking stock solution having a total concentration of 0.3% by weight of pulp and filler is prepared.
Is stirred at a rotation speed of 1000 rpm, and 15 minutes from the start of stirring.
Cationized starch (C1) with a concentration of 0.5% by weight after seconds
After adding 6 ml of an aqueous solution and continuing stirring for a predetermined time, 0.5% by weight of (D1) obtained in Production Example 1 was further added.
Add aqueous solution and stir for 15 seconds. Immediately, the freeness (milliliter) was measured using a Canadian Standard Freeness Tester. The amount of the added component (D1) was changed within the addition amount range shown in Examples 22 to 26 of Table 3 with respect to the total of the pulp and the filler.

The papermaking stock solution (α) prepared in the above (ii) was diluted with water to prepare a papermaking stock solution having a total concentration of pulp and filler of 0.3% by weight, and 1000 g of the papermaking stock solution. Is stirred at a rotation speed of 1200 rpm,
After 15 seconds from the start of stirring, 3 ml of an aqueous solution of a cationic polyacrylamide (C2) having a concentration of 0.08% by weight was added, and stirring was continued for a predetermined time, and then 0.1 (D1) obtained in Production Example 1 was further added. Add a wt% aqueous solution and stir for 15 seconds. Immediately, the freeness (milliliter) was measured using a Canadian Standard Freeness Tester.
The amount of the added component (D1) was changed within the addition amount range shown in Examples 27 to 31 of Table 3 with respect to the total of the pulp and the filler.

[0055]

[Table 3] Table 3 Example rotation speed (rpm) C component D1 component addition amount (ml) Freeness (ml) 22 1000 C1 0 530 23 23 C 1 0.6 635 24 1000 C1 1.2 675 25 1000 C1 1.8 685 26 1000 C1 2.4 698 27 1200 C2 0 558 28 28 1200 C2 0.6 671 29 1200 C2 1.2 699 30 1200 C2 1.8 705 31 1200 C2 3.0 713 As shown in Table 1, in the paper making method of the present invention, the pH of the paper making method is in the neutral range. In the undiluted solution, good aggregates are formed which are composed of cellulose fiber (A), inorganic filler (B), cationic polymer (C) and a product (D) obtained by reacting a sulfonated amino resin with an amino group-containing substance. for,
A high yield can be achieved in the papermaking process. Further, since the yield increases with an increase in the component (D), it was found that the component (D) effectively acts to improve the yield in the above composition. In the above examples, it was found that the addition of the component (D) shows good drainage.

On the other hand, in Table 2, (A), (B) and (C)
The yield was 38.0 to 46.0% when the component (D) was not added. When a sodium sulfonate-containing melamine-formaldehyde condensate (SMF) is used in place of the component (D) used in the present invention, the yield is 48.0 to 51.5% and the pH is in the neutral range. High yields from papermaking stock solutions were not achieved. Furthermore, in Comparative Examples 7 to 9, the yield ratio saturates at about 50% even if the amount of SMF added is increased, so higher yields cannot be obtained with compositions using SMF. Further, in the drainage test similarly evaluated, good results were not obtained.

When only the component (C) is added to the acidic papermaking stock solution having a pH of about 4.5, or when the component (C) and the SM are mixed with each other.
When F is added, a sufficient yield cannot be obtained, but even in these acidic papermaking stock solutions, the yield is improved by adding the components (C) and (D). The present invention has an acidic range of pH 4 to 5.5 and a pH of 5.5 to 1.
A papermaking stock solution in the range of 0 neutral to weakly alkaline shows a good yield improving effect.

[0058]

INDUSTRIAL APPLICABILITY In the papermaking stock solution to which the cationic or amphoteric polymer and the product obtained by reacting the sulfonated amino resin and the amino group-containing substance are added in the present invention, (cellulose fiber)-(inorganic filler) )-(Cationic or amphoteric polymer)-(a product obtained by reacting a sulfonated amino resin and an amino group-containing substance) is formed, but the aggregate has a strong cohesive force and is a papermaking stock solution. Among them, it exhibits toughness having sufficient resistance to the effects of impurities, electrolytes, shearing forces, etc., and stably yields improved yield and drainage in the papermaking process. This improvement in yield and drainage improves the productivity of product paper, reduces the cost of treating white water, increases the efficiency of reuse of white water, reduces the heat energy in the drying process, and further improves the durability of the papermaking machine. It brings great advantages to the paper production process, such as improving. Further, the paper of the product obtained by the papermaking method of the present invention has good paper strength due to the paper strength-enhancing effect caused by the amino resin, and also has good paper quality and formation quality.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naonobu Urabata 3-7-1 Kandanishikicho, Chiyoda-ku, Tokyo Nissan Chemical Industry Co., Ltd.

Claims (6)

[Claims] 1. A papermaking stock solution containing cellulosic fibers (A) or an inorganic filler (B) and papermaking and dehydration,
In a papermaking method by drying, a cationic or amphoteric polymer (C) and a product (D) obtained by reacting a sulfonated amino resin and an amino group-containing substance are added to the papermaking stock solution for papermaking. A papermaking method characterized by: 2. The component (C) polymer is a cationic or amphoteric starch, a cationic or amphoteric polyacrylamide derivative, a cationic or amphoteric guar gum, polydimethylaminoethyl methacrylate, polyethyleneimine, polyamide-polyamine-epichlorohydrin. The paper manufacturing method according to claim 1, which is a resin or a mixture thereof. 3. The product according to claim 1, wherein the component (D) is a product obtained by reacting a sulfonated amino resin and an amino group-containing substance in a weight ratio of 1: 0.05 to 3. The described paper manufacturing method. 4. A product obtained by reacting component (D) with a sulfonated amino resin and an amino group-containing substance in a weight ratio of 1: 0.05 to 3, and a primary product of 1 to 100 nm. The papermaking method according to any one of claims 1 to 3, which is used as a sol in which particles having a particle size are dispersed in an aqueous medium. 5. The sulfonated amino resin used in the synthesis of component (D) is a sulfonate-containing melamine-formaldehyde condensate.
The method for making paper according to item. 6. The paper manufacturing method according to claim 1, wherein the amino group-containing substance used in the synthesis of component (D) is melamine.