JP4590194B2 - High-quality paper - Google Patents

Description

  The present invention relates to a high-quality paper that is bulky, has a small decrease in stiffness, has a high friction coefficient, and is excellent in printing workability.

  Comic books and paperbacks have rapidly spread, reflecting the recent separation of print. Along with this, paper is also required to be lighter. Here, the weight reduction of paper refers to weight reduction while maintaining the thickness of the paper, that is, increase in bulk (reduction in density). Now that environmental problems are being sought, paper weight reduction is an unavoidable problem in making effective use of paper pulp made from forest resources.

  As a conventional technique for increasing the bulk of paper, there is a method of using a bulky pulp composition obtained by reacting a mixture of pulp and hydrophobic fibers with a crosslinking agent (see Patent Document 1). In addition, there is a method for producing a bulky pulp sheet by mixing cellulose pulp, a specific form of polyester composite fiber, and a heat-fusible binder (see Patent Document 2). However, the use of cross-linked pulp, synthetic fibers, etc. has the problem of making paper impossible to recycle. Further, there is a technique for producing a bulky neutral paper by filling hollow spherical vaterite type calcium carbonate (see Patent Document 3), but there is a problem that it is a special filler. In addition, there is a method of producing a low-density bulky paper by making paper from pulp and heat-expandable particles (see Patent Document 4). The method using foamable particles has a problem that the paper strength is remarkably lowered. Also, there is a method using bacterial cellulose and expandable particles (see Patent Document 5), but a special cellulose called bacterial cellulose must be used, which is not practical.

  In the method using a surfactant, a bulking agent for paper containing a specific alcohol and / or a polyoxyalkylene adduct thereof is disclosed (see Patent Document 6). There is also a method using a nonionic surfactant (see Patent Document 7). Further, a paper bulking agent comprising a polyhydric alcohol and a fatty acid ester compound (see Patent Document 8) is disclosed, and there is a technique in which this paper bulking agent is applied to paperboard (see Patent Document 9).

  By using these known bulking agents, it is possible to make the paper bulky, but some known bulking agents simultaneously cause a sharp decrease in the coefficient of friction of the paper. When offset printing is performed on paper with such a reduced coefficient of friction, there is a problem that troubles in printing runnability such as paper run-off, which is called paper flow, and tension fluctuation at the time of paper change occur.

  Non-surfactant-based bulking agent technology discloses a paper bulking agent containing at least one compound selected from a cationic compound having a specific structure, an amine, an acid salt of an amine, and an amphoteric compound. (See Patent Document 10). There is also a bulking agent of the fatty acid polyamide polyamine type. However, when these bulking agents are added, it is possible to make the paper bulky, but at the same time, a remarkable reduction in paper strength and stiffness occurs.

Patent No. 2903256 Japanese Patent No.2591685 Japanese Patent No. 1755152 Japanese Patent Laid-Open No. 5-230798 Japanese Patent Laid-Open No. 11-200282 International Publication No. 98/03730 Pamphlet JP 11-200283 A Patent No. 2971447 Specification Patent No. 3041294 JP 11-269799 A

  While some high quality papers require flexibility, there are many uses that often cause problems when the stiffness is extremely reduced compared to conventional high quality paper. Further, since the reduction in stiffness has a surface that impairs the quality of the high-quality paper, the high-quality paper requires a certain degree of rigidity.

  As described above, it has been desired to develop a high-quality paper that is bulky, has a small decrease in rigidity, has a high friction coefficient, and is excellent in printing workability.

  An object of the present invention is to provide a high-quality paper having the characteristics that it is bulky and has a small decrease in stiffness, a high friction coefficient, and excellent printing workability.

  An internal paper quality improver comprising a polymer emulsion comprising a natural cationic polymer (A) and polymer particles (B) containing at least a constituent unit derived from a vinyl monomer, and a filler in an amount of 5 to 40% by weight. Then, paper containing the stock is made to obtain a high quality paper having a coefficient of dynamic friction of 0.20 to 0.75.

  The high-quality paper of the present invention is more bulky than conventional high-quality paper obtained by internally adding a bulking agent, and has the effect that the rigidity is less reduced, the friction coefficient is high, and the printing workability is excellent.

  The paper quality improver used in the present invention is a substance described in Japanese Patent Application No. 2003-302300, and includes a natural cationic polymer (A) and polymer particles (B) containing at least a constituent unit derived from a vinyl monomer. An internal additive paper quality improver comprising a polymer emulsion containing

<Natural cationic polymer (A)>
The natural cationic polymer (A) used in the present invention is obtained by chemically modifying a polymer obtained from a natural product by an operation such as extraction or purification and the polymer. Those having a glucose residue in the polymer skeleton (starch residue, cellulose residue, etc.) are preferred, for example, cationic starch or cationic cellulose (especially water-soluble and those having a cation group being a quaternary ammonium cation group are preferred). Etc., and one or more of them may be used alone or as a mixture of two or more.

  The cationic group includes an ammonium group or an amino group neutralized with an acid. Preferably, the amino group is neutralized with hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, tartaric acid, adipic acid, lactic acid or the like.

  As the cationic starch or the cationic cellulose, for example, those represented by the following formula (1) are preferable.

(Where
A: starch residue or cellulose residue,
R: an alkylene group or a hydroxyalkylene group,
R ¹ , R ² and R ^{3 are the} same or different and may form an alkyl group, an aryl group, an aralkyl group or a nitrogen atom in the formula to form a heterocyclic ring.
X-: represents a counter ion of an ammonium salt.
i: Indicates a positive integer. )

  As a starch residue or a cellulose residue, what remove | excluded i hydroxyl groups from starch or cellulose is mentioned preferably.

  R is preferably an alkylene or hydroxyalkylene group having 1 to 12 carbon atoms, more preferably 1 to 3 carbon atoms, and particularly preferably a hydroxypropylene group.

R ¹ , R ² and R ³ are preferably an alkyl group having 1 to 12 carbon atoms, more preferably 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, an i-propyl group, and an n-propyl group. It is done. Specific examples of X- include halogen ions such as chlorine, iodine and bromine, and organic anions such as sulfuric acid, sulfonic acid, methyl sulfuric acid, phosphoric acid and nitric acid. i is determined according to the above-mentioned degree of cation substitution.

  In the present invention, the natural cationic polymer is produced by a known method. For example, corn starch or the like is cationized in a water / alcohol system using a cationizing agent, and then neutralized with acetic acid, washed with water, and dried. The molecular weight (aqueous solution viscosity) is generally easily adjusted by adding a strong acid such as hydrochloric acid to a cationized slurry and heating the slurry.

  Cationic starch is obtained, for example, by reacting raw starch or modified starch from corn, potato, tapioca, wheat, rice, etc. with glycidyltrimethylammonium chloride or 3-chloro-2-hydroxypropyltrimethylammonium chloride under alkaline conditions. I can do things. It can also be obtained by quaternizing dimethylaminoethylated starch. Furthermore, it can also be obtained by reacting starch with 4-chlorobutenetrimethylammonium chloride. On the other hand, cationic cellulose can be obtained by, for example, performing the above reaction on hydroxyethyl cellulose.

  The nitrogen content of the natural cationic polymer is preferably 0.05 to 1% by weight, particularly preferably 0.07 to 0.9% by weight, from the viewpoint of improving rigidity. Nitrogen weight% (hereinafter referred to as N%) is preferably 0.05% by weight or more from the viewpoint of rigidity improvement effect, and 1% by weight or less is preferable from the viewpoint of rigidity improvement effect. N% is analyzed by Kjeldahl method (JIS K 8001).

  The natural cationic polymer should have a low molecular weight within the range that does not impair the effects of the present invention, since high solid differentiation of the emulsion is desired in consideration of the convenience of handling and handling, as well as productivity. Can do. When the molecular weight of the natural cationic polymer is replaced with aqueous solution viscosity, 40 to 10,000 mPa · s is preferable as 50 ° C., 7 wt% aqueous solution viscosity (B-type viscometer, rotor No. 2, 60 rpm), 50 to 8,000 mPa · s is more preferable.

  The natural cationic polymer may be introduced with a functional group such as an ether group such as a hydroxyalkyl group or an ester group such as an acetyl group in order to prevent aging, as long as the effect of the present invention is not impaired.

  For the purpose of improving polymerization stability and mechanical stability, for example, a synthetic cationic polymer or a nonionic polymer other than the natural cationic polymer may be used in combination with the natural cationic polymer. The synthetic cationic polymer is preferably cationized polyvinyl alcohol, and the nonionic polymer is preferably a semi-synthetic water-soluble polymer such as methyl cellulose, hydroxyethyl cellulose, or soluble starch; or a synthetic water-soluble polymer such as polyvinyl alcohol. The amount of the polymer other than the natural cationic polymer used is preferably 0 to 100 parts by weight, more preferably 0 to 50 parts by weight, based on 100 parts by weight of the vinyl monomer constituting the polymer particles (B). .

<Polymer particles (B)>
The polymer particles (B) used in the present invention preferably have a glass transition temperature (Tg) of 90 ° C. or lower, and more preferably 80 ° C. or lower. When the Tg of the polymer is 90 ° C. or lower, part or all of the internally added paper quality improver contained in the paper is melted in the paper manufacturing process, which is preferable from the viewpoint of rigidity improvement performance. The lower limit of Tg is not particularly limited, but is preferably −10 ° C. or higher.

  The polymer particles used in the present invention contain structural units derived from vinyl monomers. The content of the constituent vinyl monomer in the polymer particles is not particularly limited, but is preferably 50 to 100 mol%, particularly preferably 80 to 100 mol%. As a vinyl monomer, a vinyl compound, a vinylene compound, a vinylidene compound, and a cyclic olefin are contained, What is described below is mentioned preferably.

(1) Methyl (meth) acrylate ((meth) acryl is acrylic, methacrylic or a mixture thereof; the same shall apply hereinafter), ethyl (meth) acrylate, isopropyl (meth) acrylate, (meth) acrylic acid (Meth) acrylic acid alkyl esters having an alkyl group having preferably 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, such as butyl, isobutyl (meth) acrylate, t-butyl (meth) acrylate;
(2) Fatty acid vinyl ester comprising an ester of a linear or branched fatty acid having 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate, and vinyl alcohol. Kind;
(3) (Meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamide-2- Anionic monomers having a polymerizable unsaturated group such as methyl propane sulfonic acid, vinyl sulfonic acid and styrene sulfonic acid, or salts thereof may be mentioned. Polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid include acid anhydrides, partial esters and partial amides or mixtures thereof. Examples of the “salt” include alkali metal salts (sodium salt, potassium salt, lithium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, barium salt, etc.), ammonium salts (quaternary ammonium salt, quaternary ammonium salt, etc. Quaternary alkyl ammonium salts, etc.). Of these, sodium salts are the cheapest and preferred.

  (4) (Meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) Polymerizable unsaturation such as acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, N-vinylpyrrolidone, N-vinylacetamide Nonionic hydrophilic group-containing monomer having a group.

  (5) Amino group having a polymerizable unsaturated group such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, etc. Specific examples of the monomer-containing monomer or its acid neutralized product or its quaternized product can be given. Preferred acids for obtaining an acid neutralized product include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, tartaric acid, adipic acid, lactic acid and the like. Examples of the alkylating agent include alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide, and general alkylating agents such as dimethyl sulfate, diethyl sulfate and di-n-propyl sulfate.

(6) Styrene, α-methylstyrene Among the above vinyl monomers, it is most preferable to use fatty acid vinyl esters to improve the rigidity of the paper. The polymer particles used in the present invention can be obtained by emulsion polymerization, suspension polymerization or dispersion polymerization.

(Polymer emulsion)
In the present invention, in the emulsion, the polymer particles (B) described above are preferably 5 to 60% by weight, more preferably 10 to 60% by weight in terms of solid pure content (solid content concentration) from the viewpoint of ease of handling. More preferably, it is contained in an amount of 15 to 55% by weight. The average particle size of the polymer particles (B) is preferably from 0.01 to 50 μm, more preferably from 0.1 to 30 μm, particularly preferably from 0.2 to 20 μm, from the viewpoints of emulsion stability, adsorbability to pulp, and the like. The solid content concentration is measured by the method described in Examples below.

  In the paper quality improver of the present invention, in order to effectively adsorb the polymer particles (B) to the pulp and improve the rigidity of the pulp sheet, the natural system in the emulsion is used. The ratio of the cationic polymer (A) is preferably 5 to 200 parts by weight, more preferably 5 to 150 parts by weight, and particularly preferably 7 to 120 parts by weight with respect to 100 parts by weight of the polymer particles (B). In this ratio, the weight of the polymer particles (B) is the total weight of all monomers constituting the polymer.

  In order to effectively adsorb the polymer particles (B) to the pulp and also to obtain an auxiliary effect of improving the rigidity by the natural cationic polymer (A), the ratio of the natural cationic polymer (A) in the emulsion However, it is preferably 5 to 500 parts by weight, more preferably 7 to 500 parts by weight, and particularly preferably 10 to 500 parts by weight with respect to 100 parts by weight of the polymer particles (B).

  The emulsion of the present invention preferably contains 40 to 90% by weight, more preferably 45 to 85% by weight of a dispersion medium. The dispersion medium is preferably water, but may contain a lower alcohol having 1 to 4 carbon atoms. Examples of the lower alcohol include methyl, ethyl, isopropyl alcohol having 1 to 3 carbon atoms.

  Furthermore, in addition to preservatives and bactericides, additives such as calcium carbonate, talc and white carbon, pigments and the like may be contained as additives.

  The inventors of the present invention have studied high-quality paper containing the above-mentioned paper quality improver and have completed the present invention.

  The present invention relates to fine paper, and the pulp to be used is not limited to mechanical pulp. Specifically, hardwood chemical pulp, softwood chemical pulp, high-quality waste paper pulp and the like can be used in any proportion. .

  The fine paper of the present invention may be produced by acid papermaking or produced by neutral papermaking. Since calcium carbonate is more effective in increasing the bulk of the paper than other fillers, neutral papermaking using at least calcium carbonate as a filler is more preferable.

  For high quality paper of acidic papermaking, known internal sizing agents for acidic papermaking such as rosin sizing agent, reinforced rosin sizing agent, and synthetic sizing agent can be used. The addition amount of the internal sizing agent for acidic papermaking is preferably 0.05 to 5% by weight, more preferably 0.05 to 1% by weight, based on the pulp. In addition, it is possible to use a filler that is stable even when the paper pH is in the acidic range, specifically, inorganic fillers such as clay, calcined kaolin, deramikaolin, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, and urea-holimarin resin. Organic fillers such as polystyrene resin, phenol resin, and fine hollow particles can be used alone or in appropriate combination of two or more. The filler content in the paper is 5 to 40% by weight, preferably 10 to 40% by weight, more preferably 10 to 35% by weight, and most preferably 10 to 30% by weight. If the filler is less than 5% by weight, the opacity and smoothness of the resulting acidic fine paper are insufficient, and if the filler exceeds 40% by weight, the paper strength will decrease and it will be difficult to operate. Increases the amount of powder generated.

  For high-quality paper made of neutral paper, one type selected from well-known internally added neutral sizing agents, alkyl ketene dimer (AKD) sizing agents, alkenyl succinic anhydride (ASA) sizing agents, and neutral rosin sizing agents. Use the sizing agent. AKD and ASA are more suitable than neutral rosin sizing agents because they tend to make paper bulky. The addition amount of the sizing agent is preferably 0.05 to 5% by weight, particularly preferably 0.1 to 1% by weight, based on the pulp. It is necessary to contain at least calcium carbonate as a filler. In addition, magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, clay, calcined kaolin, deramikaolin, titanium dioxide, oxidation One or more kinds selected from inorganic fillers such as zinc, silicon oxide, and amorphous silica, urea-holimarin resin, polystyrene resin, phenol resin, and fine hollow particles can be used in combination. The filler content in the paper is 5 to 40% by weight, more preferably 10 to 40% by weight, still more preferably 10 to 35% by weight, and most preferably 10 to 30% by weight. If the filler is less than 5% by weight, the opacity and smoothness of the neutral high-quality paper obtained are insufficient, and if the filler exceeds 40% by weight, the paper strength decreases, so there are many paper breaks, making operation difficult. The amount of paper dust generated during printing increases.

  There are heavy calcium carbonate and light calcium carbonate in calcium carbonate, but from the viewpoint of reducing wire wear during paper making and increasing the opacity and smoothness of the resulting neutral high quality paper, Is more preferably light calcium carbonate. Among the light calcium carbonates, the rosette type is more preferable.

  The place where the paper quality improver, sizing agent and filler are added is before the paper making process and is internally added. Although it is not particularly limited as long as it is a place before the papermaking process, it is preferably before a mixing chest or a secondary fan pump, and preferably before adding a yield improver.

  Even if the amount of the paper quality improver is increased beyond a certain level, the bulking effect is likely to reach a peak, so the bulking agent is added in the range of 0.1 to 20% by solid weight to the raw material pulp. In order to fully develop the effect of the bulking agent without changing the paper quality (excluding bulk) so much, 0.1 to 5% by weight of solid content is preferable.

  In the method for producing fine paper of the present invention, various conventionally used nonionic, cationic retention agents, freeness improvers, paper strength improvers, and the like are used as necessary for papermaking internal additives. It is appropriately selected and used.

  Further, for example, sulfuric acid bands, aluminum chloride, sodium aluminate, basic aluminum compounds such as basic aluminum chloride and basic polyaluminum hydroxide, water-soluble aluminum compounds such as water-degradable alumina sol, sulfuric acid A polyvalent metal compound such as ferrous sulfate or ferric sulfate, silica sol, or the like may be internally added.

  Other starches for papermaking, various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic cross-linked polymer Various compounds such as particle dispersions and derivatives or modified products thereof can be used.

  Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be appropriately added depending on the intended use.

  The type of the paper machine is not particularly limited, and can be appropriately made with a long net paper machine, a twin wire paper machine, a Yankee paper machine, or the like. The press line pressure is used within the normal operating range. The surface treatment agent may or may not be applied. When applying the surface treatment agent, there are no particular limitations on the components of the surface treatment agent, and the size press type is also not limited, and a liquid film transfer type size press such as a 2-roll size press, a gate roll size press, or a shim sizer. Etc. can be used as appropriate. The calendar is used at a linear pressure within the normal operating range, but from the viewpoint of producing bulky high quality paper, a low linear pressure or a bypass is preferable as long as the smoothness of the paper can be maintained. A soft calendar is preferred.

  The surface treatment agent is not particularly limited, for example, raw starch, oxidized starch, esterified starch, cationized starch, enzyme-modified starch, aldehyde-modified starch, modified starch such as hydroxyethylated starch, carboxymethylcellulose, hydroxyethylcellulose, Cellulose derivatives such as methylcellulose, modified alcohols such as polyvinyl alcohol and carboxyl-modified polyvinyl alcohol, styrene butadiene copolymer, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic acid ester, Polyacrylamide can be used alone or in combination. Among them, the application of hydroxyethylated starch, which is excellent in the effect of improving the surface strength, is most preferable. In addition to the above-mentioned agents, surface sizing agents such as styrene acrylic acid, styrene maleic acid, olefinic compounds, and cationic sizing agents can be applied to the surface treatment agent.

  The dynamic friction coefficient of the fine paper of the present invention produced as described above is in the range of 0.20 to 0.75, preferably 0.30 to 0.75, more preferably 0.40 to 0.75, and still more preferably 0.50 to 0.75. If the dynamic friction coefficient is less than 0.20, troubles in printing runnability such as paper running failure and tension fluctuation at the time of paper change occur during offset printing. It is difficult to make the coefficient of dynamic friction over 0.75 in high-quality paper.

  The paper quality improver used in the present invention has a remarkable effect of increasing the bulk of paper, but has a feature that the decrease in stiffness is small. Furthermore, there is little decrease in the dynamic friction coefficient. Therefore, this paper quality improver can be highly blended, and accordingly, high-quality paper with higher rigidity and low density can be produced. High quality paper refers to paper defined by JIS P0001 (6008), and is used, for example, as printing paper A defined by JIS P 3101, writing paper defined by JIS P 3102, and the like. Further, among these applications, since the coefficient of dynamic friction is high, it is preferably used for offset printing paper among these applications.

  Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified, “parts” is parts by weight and “%” is% by weight.

<Examples of emulsion production>
Table 1 shows the compositions and physical properties of emulsions 1 to 15 (EM-1 to EM-15) shown below.
・ Emulsion 1 (EM-1)
In a 2 L flask equipped with a reflux condenser, dropping funnel, thermometer, nitrogen inlet, and stirrer, cationic starch A [N% = 0.6%, 7% aqueous solution viscosity 260 mPa · s (50 ° C., B-type viscometer, rotor No. 2, 60 rpm)] 48.2 g and ion exchange water 695.0 g were charged and heated to 90 ° C. to dissolve. After cooling, 29.3 g of Emulgen 150 (nonionic surfactant, 20% aqueous solution, manufactured by Kao Corporation), 1.9 g of 75% phosphoric acid aqueous solution and 45.0 g of 4% sodium hydroxide in 17.2 g of ion-exchanged water in advance After adding the mixed aqueous solution, the mixture was stirred at 120 rpm, heated to 60 ° C. while blowing nitrogen, and held for 30 minutes. Next, 20.4 g of vinyl acetate (manufactured by Shin-Etsu Vinyl Acetate) and 1.1 g of initiator (V-50, azo initiator, Wako Pure Chemical Industries) dissolved in 29.6 g of ion-exchanged water were added. And held for 15 minutes. Next, after heating to 77 ° C., a mixture of 409.3 g vinyl acetate, 11.0 g methacrylic acid (manufactured by Mitsubishi Rayon Co., Ltd.), and 0.9 g initiator (V-50) dissolved in 210 g ion-exchanged water Each was dropped from a separate dropping funnel over 3 hours to carry out polymerization. Next, the temperature was raised to 82 ° C., aged for 1 hour, cooled, and taken out. A cationic emulsion 1 having a solid content concentration of 30.8% and an average particle size of 2.63 μm was obtained.

・ Emulsion 2 (EM-2)
In accordance with the production method of Emulsion 1, using the same apparatus, cationic starch A (N% = 0.6%, 7% aqueous solution viscosity 260 mPa · s (50 ° C., B-type viscometer, rotor No. 2, 60 rpm)) 48.2 g, polyvinyl alcohol (GL-05, polymerization degree 500, saponification degree 88 mol%, manufactured by Nippon Synthetic Chemical Co., Ltd.) 8.1 g and ion-exchanged water 585.2 g were charged and heated to 90 ° C. to dissolve. After cooling, 29.3 g of Emulgen 150 (nonionic surfactant, 20% aqueous solution, manufactured by Kao Corporation), 1.9 g of 75% phosphoric acid aqueous solution and 45.0 g of 4% sodium hydroxide in 17.2 g of ion-exchanged water in advance After adding the mixed aqueous solution, the mixture was stirred at 120 rpm, heated to 60 ° C. while blowing nitrogen, and held for 30 minutes. Next, 20.4 g of vinyl acetate (manufactured by Shin-Etsu Vinyl Acetate) and 1.1 g of initiator (V-50, azo initiator, Wako Pure Chemical Industries) dissolved in 29.6 g of ion-exchanged water were added. And held for 15 minutes. Next, after heating to 77 ° C., a mixture of vinyl acetate 205.0 g, methacrylic acid (Mitsubishi Rayon Co., Ltd.) 5.5 g, dimethylacrylamide (reagent, Wako Pure Chemical Industries, Ltd.) 6.6 g, and an initiator ( A solution prepared by dissolving 0.35 g of V-50) in 101 g of ion-exchanged water was dropped from a separate dropping funnel over 3 hours to carry out polymerization. Next, the temperature was raised to 82 ° C., aged for 1 hour, cooled, and taken out.
A cationic emulsion 2 having a solid content concentration of 23.5% and an average particle size of 0.52 μm was obtained.

・ Emulsions 3 to 13 (EM-3 to EM-13)
According to Emulsion 2, the monomer compositions of the cationic polymer and polymer particles (B) were changed as shown in Tables 1 and 2 to synthesize each (polyvinyl alcohol was 16.8% with respect to 100 parts by weight of the cationic polymer). The amount of ion-exchanged water was appropriately changed).

・ Emulsion 14 (EM-14)
In accordance with the production method of Emulsion 1, using the same apparatus, cationic starch A (N% = 0.6%, 7% aqueous solution viscosity 260 mPa · s (50 ° C., B-type viscometer, rotor No. 2, 60 rpm)) 28.9 g, polyvinyl alcohol (GL-05, polymerization degree 500, saponification degree 88 mol%, manufactured by Nippon Synthetic Chemical Co., Ltd.) 4.8 g and ion-exchanged water 539.7 g were charged and heated to 90 ° C. to dissolve. After cooling, 21.3 g of Emulgen 150 (nonionic surfactant, 20% aqueous solution, manufactured by Kao Corporation), and 1.1 g of 75% phosphoric acid aqueous solution and 26.6 g of 4% sodium hydroxide in 10.2 g of ion-exchanged water in advance. After adding the mixed aqueous solution, the mixture was stirred at 120 rpm, heated to 60 ° C. while blowing nitrogen, and held for 30 minutes. Next, 10.7 g of vinyl acetate Z (manufactured by Shin-Etsu Vinyl Acetate Co., Ltd.) and 1.0 g of initiator (V-50, azo initiator, Wako Pure Chemical Industries, Ltd.) dissolved in 9.0 g of ion-exchanged water Added and held for 15 minutes. Next, the temperature was raised to 77 ° C., aged for 1 hour, cooled, and taken out. A cationic emulsion 14 having a solid content concentration of 7.9% and an average particle size of 0.20 μm was obtained.

・ Emulsion 15 (EM-15)
In accordance with the production method of Emulsion 1, using the same apparatus, cationic starch A (N% = 0.6%, 7% aqueous solution viscosity 260 mPa · s (50 ° C., B-type viscometer, rotor No. 2, 60 rpm)) 28.9 g, polyvinyl alcohol (GL-05, polymerization degree 500, saponification degree 88 mol%, manufactured by Nippon Synthetic Chemical Co., Ltd.) 4.8 g and ion-exchanged water 539.7 g were charged and heated to 90 ° C. to dissolve. After cooling, 21.3 g of Emulgen 150 (nonionic surfactant, 20% aqueous solution, manufactured by Kao Corporation), and 1.1 g of 75% phosphoric acid aqueous solution and 26.6 g of 4% sodium hydroxide in 10.2 g of ion-exchanged water in advance. After adding the mixed aqueous solution, the mixture was stirred at 120 rpm, heated to 60 ° C. while blowing nitrogen, and held for 30 minutes. Next, 10.7 g of vinyl acetate (manufactured by Shin-Etsu Vinyl Acetate Co., Ltd.) and 1.0 g of initiator (V-50, azo initiator, Wako Pure Chemical Industries, Ltd.) dissolved in 9.0 g of ion-exchanged water are added. And held for 15 minutes.
Next, after raising the temperature to 77 ° C., a mixture of vinyl acetate 54.3 g, methacrylic acid (manufactured by Mitsubishi Rayon Co., Ltd.) 1.6 g, dimethylacrylamide (reagent, Wako Pure Chemical Industries, Ltd.) 1.9 g, and an initiator ( A solution prepared by dissolving 0.85 g of V-50) in 130 g of ion-exchanged water was dropped from a separate dropping funnel over 3 hours to carry out polymerization. Next, the temperature was raised to 82 ° C. and aged for 1 hour, and then cooled and taken out. A cationic emulsion 15 having a solid content concentration of 13.1% and an average particle size of 0.43 μm was obtained.

(note)
1) Each cationic polymer is as follows.
-Cationized HEC: Wako Pure Chemical Industries, Ltd.-Cationized cellulose: Wako Pure Chemical Industries, Ltd.-Ace K-36, K-100, K-250, K-500: Cationized starch (Oji Corn Starch Co., Ltd.) ))
・ Cationized starch B: N% = 0.8%, 7% aqueous solution viscosity 2000mPa · s
-PVA-1: Mercapto-modified polyvinyl alcohol (M-115, polymerization degree 1500, manufactured by Kuraray Co., Ltd.)
PVA-2: cationized polyvinyl alcohol (C-506, polymerization degree 600, manufactured by Kuraray Co., Ltd.)
2) Each monomer is as follows.
-VAc: Vinyl acetate-St: Styrene-MAA: Methacrylic acid-AA: Acrylamide-GMAC: Hydroxypropylmethylammonium chloride methacrylate-DMAAm: Dimethylacrylamide-MMA: Methyl methacrylate-BMA: Butyl methacrylate-BA: Acrylic acid The amount of butyl 3) (A) added is% by weight relative to the vinyl monomer in the monomer composition of the polymer particles (B).

<Manufacture of fine paper>
[Example 1]
Only LBKP (freeness CSF 400 ml) was used as the pulp content, and light calcium carbonate was added to this so that the content was 5%. For solids (pulp + filler) solid weight, 1.0% by weight of the internal paper improver EM-8 in Table 1 and 1.0% by weight of sulfuric acid band (50% by weight of sulfuric acid band product), cation A stock was prepared by adding 0.5% by weight of modified starch and 0.1% by weight of alkyl ketene dimer sizing agent, respectively. Using a twin wire paper machine, high-quality paper having a basis weight of 80 g / m ² was obtained at a jet / wire ratio of 101% and a paper making speed of 500 m / min. The linear pressure of No. 1 press (hereinafter referred to as 1P) is 60kgf / cm, 2P is 60kgf / cm, 3P is 70kgf / cm, the surface treatment agent is not applied, and the calendar is released (untreated). .
Table 2 shows the paper quality results.
<Measurement of paper quality>
Density: Measured according to JIS P 8118.
-Stiffness: Using a pure bending property tester (manufactured by SMT Co., Ltd.), the stiffness in the MD direction was measured, and in order to avoid the influence of the paper thickness, the value obtained by the following calculation formula was used as the stiffness.
Stiffness = 10 ⁵ × Pure bending stiffness measurement value / (paper thickness) ³
Here, the unit of the measured value of pure bending stiffness is μN · m ² / m, and the unit of paper thickness is μm.
-Coefficient of dynamic friction: Measured according to JIS P 8147. The front and back surfaces of the manufactured fine paper were superimposed and measured in the MD direction.

[Example 2]
A fine paper was obtained in the same manner as in Example 1 except that the light calcium carbonate content was 20%.
Table 2 shows the paper quality results.

[Example 3]
A fine paper was obtained in the same manner as in Example 1 except that the light calcium carbonate content was 40%.
Table 2 shows the paper quality results.

[Example 4]
Only LBKP (freeness CSF 400 ml) was used as the pulp content, and light calcium carbonate was added to this so that the content was 5%. For solids (pulp + filler) solid weight, 1.0% by weight of the internal paper improver EM-8 in Table 1 and 1.0% by weight of sulfuric acid band (50% by weight of sulfuric acid band product), cation A paper stock was prepared by adding 0.5% by weight of modified starch and 0.1% by weight of alkenyl succinic anhydride sizing agent. Using a twin wire paper machine, high-quality paper having a basis weight of 80 g / m ² was obtained at a jet / wire ratio of 101% and a paper making speed of 500 m / min. The linear pressure of No. 1 press (hereinafter referred to as 1P) is 60kgf / cm, 2P is 60kgf / cm, 3P is 70kgf / cm, the surface treatment agent is not applied, and the calendar is released (untreated). .
Table 2 shows the paper quality results.

[Example 5]
A fine paper was obtained in the same manner as in Example 4 except that the light calcium carbonate content was 20%.
Table 2 shows the paper quality results.

[Example 6]
A fine paper was obtained in the same manner as in Example 4 except that the light calcium carbonate content was 40%.
Table 2 shows the paper quality results.

[Example 7]
Only LBKP (freeness CSF 400 ml) was used as the pulp content, and light calcium carbonate was added to this so that the content was 5%. For solids (pulp + filler) solid weight, 1.0% by weight of the internal paper improver EM-8 in Table 1 and 1.0% by weight of sulfuric acid band (50% by weight of sulfuric acid band product), cation A stock was prepared by adding 0.5% by weight of modified starch and 0.1% by weight of neutral rosin sizing agent. Using a twin wire paper machine, high-quality paper having a basis weight of 80 g / m ² was obtained at a jet / wire ratio of 101% and a paper making speed of 500 m / min. The linear pressure of No. 1 press (hereinafter referred to as 1P) is 60kgf / cm, 2P is 60kgf / cm, 3P is 70kgf / cm, the surface treatment agent is not applied, and the calendar is released (untreated). .
Table 2 shows the paper quality results.

[Example 8]
A fine paper was obtained in the same manner as in Example 7 except that the light calcium carbonate content was 20%.
Table 2 shows the paper quality results.

[Example 9]
A fine paper was obtained in the same manner as in Example 7 except that the light calcium carbonate content was 40%.
Table 2 shows the paper quality results.

[Example 10]
Only LBKP (freeness CSF 400 ml) was used as the pulp content, and talc was added to this so that the content was 20%. For solids (pulp + filler) solid weight, 1.0% solid content weight improver EM-8 in Table 1 and 2.5% sulfuric acid band (sulfate band product of 50 solid weight), rosin Paper materials were prepared by adding sizing agents to a solid content of 0.3% by weight. Using a twin wire paper machine, high-quality paper having a basis weight of 80 g / m ² was obtained at a jet / wire ratio of 101% and a paper making speed of 500 m / min. The linear pressure of No. 1 press (hereinafter referred to as 1P) is 60kgf / cm, 2P is 60kgf / cm, 3P is 70kgf / cm, the surface treatment agent is not applied, and the calendar is released (untreated). .
Table 2 shows the paper quality results.

[Example 11]
A fine paper was obtained in the same manner as in Example 2 except that the internal additive paper quality improver was changed to EM-1.
Table 2 shows the paper quality results.

[Example 12]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-2.
Table 2 shows the paper quality results.

[Example 13]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-3.
Table 2 shows the paper quality results.

[Example 14]
A fine paper was obtained in the same manner as in Example 2 except that the internal additive paper quality improver was changed to EM-4.
Table 2 shows the paper quality results.

[Example 15]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-5.
Table 2 shows the paper quality results.

[Example 16]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-6.
Table 2 shows the paper quality results.

[Example 17]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-7.
Table 2 shows the paper quality results.

[Example 18]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-9.
Table 2 shows the paper quality results.

[Example 19]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-10.
Table 2 shows the paper quality results.

[Example 20]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-11.
Table 2 shows the paper quality results.

[Example 21]
A high quality paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-12.
Table 2 shows the paper quality results.

[Example 22]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-13.
Table 2 shows the paper quality results.

[Example 23]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-14.
Table 2 shows the paper quality results.

[Example 24]
A fine paper was obtained in the same manner as in Example 2 except that the internal paper quality improver was changed to EM-15.
Table 2 shows the paper quality results.

[Comparative Example 1]
A high quality paper was obtained in the same manner as in Example 2 except that the paper quality improver EM-8 was changed to a paper quality improver KB115 (produced by Kao Corporation) which is an ester of a polyhydric alcohol and a saturated fatty acid.
Table 2 shows the paper quality results.

[Comparative Example 2]
A fine paper was obtained in the same manner as in Example 2 except that the paper-making paper quality improver EM-8 was changed to a saturated fatty acid amide-based paper quality improver PT-205 (manufactured by PMC Japan).
Table 2 shows the paper quality results.

[Comparative Example 3]
A fine paper was obtained in the same manner as in Example 2 except that the paper-making paper quality improver EM-8 was changed to an unsaturated fatty acid amide-based paper quality improver DZ2220 (manufactured by NOF Corporation).
Table 2 shows the paper quality results.

[Comparative Example 4]
A fine paper was obtained in the same manner as in Example 2 except that the paper quality improver EM-8 was changed to a paper quality improver KB08W (manufactured by Kao Corporation) which is an adduct of alcohol alkylene oxide.
Table 2 shows the paper quality results.

[Comparative Example 5]
A fine paper was obtained in the same manner as in Example 2 except that no paper quality improver was added.
Table 2 shows the paper quality results.

[Comparative Example 6]
A fine paper was obtained in the same manner as in Example 2 except that the alkyl ketene dimer sizing agent was not added.
Table 2 shows the paper quality results.

[Comparative Example 7]
A fine paper was obtained in the same manner as in Example 2 except that no light calcium carbonate was added.
Table 2 shows the paper quality results.

[Comparative Example 8]
A fine paper was obtained in the same manner as in Example 2 except that the light calcium carbonate content was changed to 45%.
Table 2 shows the paper quality results.

  From the results of Examples 1 to 3 and Comparative Example 8, it can be seen that the filler content of the fine paper of the present invention is limited to 40% by weight. From the results of Examples 2, 5, 8, 11 to 24 and Comparative Example 5, it can be seen that the high-quality paper of the present invention has a low density (bulk), a small decrease in stiffness, and no decrease in dynamic friction coefficient. In Comparative Examples 1 to 4 to which a conventional paper quality improver is added, the density of the paper can be reduced, but the density is higher than that of the present invention. Moreover, rigidity will fall in all. Further, in Comparative Examples 1 and 2, the dynamic friction coefficient also decreases. From the results of Example 10, it can be seen that the high quality acidic paper is also bulky, has little decrease in stiffness, and has a sufficient dynamic friction coefficient.

Claims (4)

Glass transition temperature containing at least one of a natural cationic polymer (A) having a nitrogen content of 0.05 to 1% by weight and at least vinyl acetate, (meth) acrylic acid, (meth) acrylic acid ester, and styrene A paper material containing an internally added paper quality improver comprising a polymer emulsion containing polymer particles (B) having a (Tg) of -10 ° C. or more and 90 ° C. or less, and a filler in an amount of 5 to 40% by weight. A high-quality paper having a coefficient of dynamic friction obtained by papermaking of 0.20 to 0.75.   The high-quality paper according to claim 1, wherein the amount of the internally added paper quality improver is 0.1 to 20% by weight based on the raw material pulp.   The high-quality paper according to claim 1 or 2, wherein the natural cationic polymer (A) is cationized starch and / or cationized cellulose.   The high-quality paper according to any one of claims 1 to 3, wherein the ratio of the natural cationic polymer (A) is 5 to 500 parts by weight with respect to 100 parts by weight of the polymer particles (B).