JP5408560B2 - Sizing composition, papermaking method, and board manufacturing method - Google Patents

Description

  The present invention relates to a sizing composition, a papermaking method, and a paperboard manufacturing method, and more specifically, a sizing composition comprising a substituted succinic anhydride as a main component, and a papermaking method and paperboard using the sizing composition. It relates to the manufacturing method.

  Alkenyl succinic anhydride (hereinafter sometimes abbreviated as ASA) is widely used as a sizing agent for imparting water resistance to paper in the papermaking field. Similarly, 2-oxetanone compounds typified by alkyl ketene dimers are also used as sizing agents, but ASA has better sizing immediately after papermaking than 2-oxetanone compounds and has a size effect on waste paper pulp and mechanical pulp. Has excellent features. In an actual papermaking process, ASA is used as an emulsion emulsified and dispersed in an aqueous medium. Since ASA is an oily substance at room temperature or in a heated state, it can be emulsified by a conventionally known emulsification method using an emulsifying dispersant and a high-speed stirrer (see, for example, Patent Document 1).

  As an emulsifying dispersant for emulsifying ASA, for example, cationized starch paste (see, for example, Patent Documents 1 and 2), vinyl-based and (meth) acrylamide-based cationic polymers (for example, refer to Patent Documents 3 and 4). Grafted cationized starch obtained by graft polymerization of monomers containing (meth) acrylamide onto cationized starch (see, for example, Patent Document 5) and amphoteric acrylamide polymers (see, for example, Patent Documents 6 and 7) have been proposed. Yes.

  However, even if the above emulsifying dispersant is used, ASA is prone to hydrolysis due to contact with moisture, and not only the size effect on paper is reduced, but also the hydrolyzed ASA hydrolyzate is not adhesive. Due to its high nature, it tends to cause dirt in the papermaking process.

  As other methods for improving the quality of an emulsified dispersion obtained by emulsifying and dispersing ASA, a method using ASA having a specific chemical structure (for example, see Patent Document 8), a method using a hydrophobic substance compatible with ASA together (For example, refer patent document 9) and the method (for example, refer patent document 10) using the sizing dispersion liquid containing ASA and a 2-oxetanone compound are proposed.

Further, Patent Document 11 states that “in a sizing mixture for improving the resistance of a cut of a liquid packaging cardboard against penetration by high-temperature hydrogen peroxide containing a cellulose-reactive sizing agent and a non-cellulose-reactive sizing agent. A sizing mixture characterized in that it comprises a thermosetting resin that can be covalently bonded to self-crosslinked cellulose fibers and the non-cellulosic reactive sizing agent is ... or a fatty acid derivative " (Refer to the claims of Patent Document 11). In Patent Document 11, “cellulose-reactive sizing agent and non-cellulose-reactive sizing agent” are listed as “cellulose-reactive sizing agents include alkenyl succinic anhydride” (paragraph number 0027 of Patent Document 11). The most preferred non-reactive sizing agent is a fatty acid ester, in particular ... a glycerol triester (glyceride) of a natural fatty acid "(see paragraph number 0031 of patent document 11). Yes.
Moreover, in the Example disclosed by patent document 11, as a fatty acid ester which is a non-cellulose reactive sizing agent, glycerol triester of C16-C18 fatty acid (Table 1 of Example 1, Table 3 and Table 4 of Example 3). Glyceryl triester of C22 fatty acid (see Table 3 of Example 3), glyceryl triester of C18 fatty acid (see Table 4 of Example 3), and fatty acid esters other than glyceryl triester There are no examples.
Patent Document 11 does not disclose a problem of providing a sizing composition that is excellent in emulsion stability and hardly causes the occurrence of soiling during use, and can function as a non-cellulose-reactive sizing agent from the viewpoint of size effect. It merely discloses a sizing mixture comprising a high melting point glycerol triester and a cellulose reactive sizing agent.

  In general, when paperboard is made from waste paper, the papermaking pH is made acidic with sulfuric acid band or sulfuric acid. This is because the effect of a rosin sizing agent generally used can be obtained efficiently.

  However, in recent years, papermaking systems have been closed due to environmental problems, and machine corrosion due to accumulation of sulfate ions derived from sulfate bands has become a problem. In addition, the calcium carbonate content in waste paper has increased in recent years, and the pH of the papermaking system is difficult to lower, and therefore the amount of sulfuric acid band used is increasing. Due to the increase in sulfate ion and calcium carbonate content due to this closure, calcium sulfate (gypsum), which is a reaction product of sulfate band and calcium carbonate, increases in the papermaking system, and this is due to precipitation in the papermaking process. There are many troubles.

  More recently, troubles due to synthetic pitches have increased in the papermaking process. Synthetic pitches are derived from ink vehicles carried from used paper, latexes used as binders for coated paper, adhesive materials used for gum tapes and labels, hot melt adhesives used as back glue for books and magazines, etc. It is a substance. The pitch adheres to the inside of the paper making apparatus and tools and causes water squeezing failure, paper breakage, and the like, thereby reducing paper productivity. In addition, the agglomerated pitch not only causes pinholes and picking on the paper surface, but also causes troubles during coating and printing, causing the paper quality to be significantly impaired.

  Currently, the papermaking pH generally used in the production of paperboard is 5 to 6.5. This is because the amount of sulfuric acid band added was reduced from the conventional acidic papermaking to avoid the above problem, and the papermaking pH was increased due to the increase in the content of calcium carbonate.

  In order to avoid the above-described problems, use of a pitch control agent has been proposed (see, for example, Patent Document 12). However, it has been insufficient to solve with only the pitch control agent.

  As a method for improving these, a pulp slurry having (1) pH 6.5 to 8.5, (2) alkalinity 50 to 400 ppm, (3) conductivity 50 to 250 mS / m, and (4) internal sizing agent is used. Although a paperboard manufacturing method characterized in that papermaking is performed by adding a slag to a pulp slurry (see, for example, Patent Document 13), it is still insufficient.

US Pat. No. 3,812,069 (Japanese Patent Laid-Open No. 49-94907) Japanese Examined Patent Publication No. 39-002305 JP-A-60-246893 Japanese Patent Publication No. 6-33597 Japanese Patent Laid-Open No. 9-111162 Japanese Patent Publication No. 3-4247 JP 58-45731 A JP-A-6-248596 (Patent No. 2915241) US Pat. No. 6,560,049 Japanese Patent No. 3834699 Japanese Patent Laid-Open No. 6-220795 U.S. Pat. No. 4,765,867 JP 2007-186822 A

  An object of the present invention is to provide a sizing agent composition that is excellent in emulsion dispersion stability and hardly causes stains in a papermaking system.

  Another object of the present invention is to provide a papermaking method that is less likely to cause stains in the papermaking system.

  Yet another object of the present invention is to provide a paperboard manufacturing method capable of preventing scale troubles and pitch troubles by reducing the occurrence of dirt in the papermaking system and providing a paperboard having an excellent size effect. It is to be.

As a result of intensive research, the inventors of the present invention have excellent emulsion stability by mixing a substituted succinic anhydride and a specific fatty acid ester at a specific ratio, and hardly cause stains in a papermaking system. The inventors have found that a sizing composition and a papermaking method can be obtained, and have completed the present invention.
In addition, by making paper by adding this sizing agent composition to a specific pulp slurry, scale trouble and pitch trouble can be prevented by reducing the occurrence of dirt in the paper making system, and the size effect is excellent. A method for producing paperboard capable of providing paperboard has been found and the present invention has been completed.

That is, the means for solving the problem is as follows:
<1> (A) A mixture of a fatty acid ester represented by the structural formula of the following formula (1) and (B) a substituted succinic anhydride is liquid under the conditions of 1 atm and 20 ° C. ,And,
The sizing composition is characterized in that the mass ratio [(A) :( B)] of the (A) fatty acid ester and the (B) substituted succinic anhydride is 50:50 to 10:90. .
R ¹ —COO—R ² Formula (1)
(However, R ¹ in the formula represents an alkyl group or alkenyl group having 5 to 30 carbon atoms, R ^{2 in} the formula represents an alkyl group having 1 to 30 carbon atoms, and R ¹ and R ² are the same. Or different.)
A preferred embodiment of the sizing composition of <1> is:
<2> (A) The fatty acid ester has 4 to 30 carbon atoms of R ² in the formula (1).

Another means for solving the above problem is as follows.
<3> A papermaking method for reducing stains in a papermaking system using the sizing composition of <1>.

Another means for solving the above-mentioned problem is as follows.
<4> (1) pH is 6.5 to 8.5,
(2) Alkalinity is 50 to 400 ppm, and (3) Conductivity is 50 to 250 mS / m.
To the pulp slurry,
(4) A paperboard production method, wherein papermaking is performed by adding the sizing agent composition according to <1>.
A preferred embodiment of the method for producing a paperboard of <4> is:
<5> (A) The fatty acid ester has 4 to 30 carbon atoms of R ² in the formula (1).
<6> In the board manufacturing method according to <4> or <5>, a pitch control agent is added to the pulp slurry according to <4>.
<7> The pulp slurry according to <4>, wherein a polyacrylamide polymer and / or starch is used as a paper strength agent in the method for producing paperboard according to any one of <4> to <6>. It is characterized by adding to.

  According to the present invention, it is possible to provide a sizing agent composition which is excellent in dispersion stability of an emulsion and hardly causes stains in a papermaking system.

  According to the present invention, it is possible to provide a papermaking method that hardly causes stains in the papermaking system.

  According to the present invention, it is possible to provide a paperboard manufacturing method capable of preventing a scale trouble and a pitch trouble by reducing the occurrence of dirt in a papermaking system and producing a paperboard having an excellent size effect. .

  The sizing composition of the present invention is (A) liquid under conditions of 1 atm and 20 ° C., and contains a fatty acid ester represented by a specific structural formula and (B) a substituted succinic anhydride in a specific ratio. To do.

  Examples of the (B) substituted succinic anhydride include compounds in which the hydrogen of the methylene group in the succinic anhydride is substituted with an alkyl group or an alkenyl group, preferably alkenyl succinic anhydride. More preferred are alkenyl succinic anhydrides which are liquid under conditions of 1 atm and 25 ° C., and particularly preferred is an addition reaction product of an internal olefin having 16 to 24 carbon atoms and maleic anhydride. Mention may be made of internal alkenyl succinic anhydrides. Here, the internal olefin is not an α-olefin (the olefin in which the position of the double bond is the position connecting the first and second carbons of the olefin), but the double bond is present in the carbon chain from the α position. Say olefin. Further, “internal alkenyl” when referred to as internal alkenyl succinic anhydride refers to an alkenyl group in which the position of the double bond is present in the carbon chain from the α-position.

  Specific examples of the internal alkenyl succinic anhydride include internal hexadecenyl succinic anhydride, internal octadecenyl succinic anhydride, internal icocenyl succinic anhydride, internal dococenyl succinic anhydride, internal tetracocenyl. Examples thereof include succinic anhydrides, and these may be used alone or in combination with a plurality of types of internal alkenyl succinic anhydrides. A mixture containing a plurality of types of internally isomerized alkenyl succinic anhydrides formed by reacting a plurality of types of internal olefins with succinic anhydride is also suitable internal alkenyl succinic anhydride. Can be adopted as.

  An alkenyl succinic anhydride substituted by an olefin having 16 to 24 carbon atoms is preferable because the size imparting effect of the sizing composition on paper is excellent. In addition, alkenyl succinic anhydride, which is an addition reaction product of an olefin containing an internal olefin and maleic anhydride, makes alkenyl succinic anhydride difficult to hydrolyze, and the size imparting effect on the paper of the sizing composition Is preferable because the decrease in the resistance is reduced.

In the analysis by ¹ H-NMR of olefin, the presence of a double bond in the olefin from the α-position of the internal olefin (position connecting the carbon at the 1st position and the carbon at the 2nd position) in the alkenyl succinic anhydride is 5.4 ppm. This can be confirmed by the presence of a peak derived from an internal olefin in the vicinity. On the contrary, the substitution of α-olefin with alkenyl succinic anhydride means that there are peaks derived from α-olefin in the vicinity of 5.0 ppm and 5.8 ppm in the analysis of olefin by ¹ H-NMR. It can be confirmed with. It is also possible to determine the mass ratio of alkenyl succinic anhydride substituted with α-olefin and alkenyl succinic anhydride substituted with internal olefin based on the integrated value of the peak.

  The internal olefin to be subjected to addition reaction with succinic anhydride can be synthesized by an ordinary organic synthesis method, and can be obtained, for example, by internal isomerization of an α-olefin using a silica-alumina catalyst. Internally isomerized olefin obtained by internal isomerization of α-olefin by a general organic synthesis method is a mixture of internal olefins in which double bond positions are formed at various positions such as 2-position and 3-position of the carbon chain. However, in this invention, in the internal isomerized olefin, which is a mixture of internal olefins formed by isomerization reaction, the position of the specific double bond of the internal olefin is not specified. As long as it is a mixture of internal olefins, each internal olefin contained in the mixture may not be specified. In the internal isomerized olefin containing various internal olefins, the α-olefin content is preferably 10% by mass or less.

  As a method for obtaining alkenyl succinic anhydride by adding maleic anhydride to the olefin, a general organic synthesis method can be applied. For example, alkenyl succinic anhydride can be obtained by gradually adding maleic anhydride to an olefin heated to 210 ° C. in a nitrogen atmosphere and stirring for 6 to 10 hours.

The (A) fatty acid ester is liquid under conditions of 1 atm and 20 ° C., and is represented by the following structural formula (1).
R ¹ —COO—R ² Formula (1)
(In the formula, R ¹ is an alkyl group or alkenyl group having 5 to 30 carbon atoms, preferably an alkyl group or alkenyl group having 8 to 24 carbon atoms, and R ² is an alkyl group having 1 to 30 carbon atoms. Preferably, it is an alkyl group having 4 to 30 carbon atoms, more preferably 4 to 24 carbon atoms, and R ¹ and R ² may be the same or different.

  The sizing agent composition may contain only one type of fatty acid ester represented by the structural formula of Formula (1), or may contain two or more types of fatty acid ester. Moreover, the said fatty acid ester being liquid at 1 atmosphere and 20 degreeC conditions is that the viscosity in 1 atmosphere and 20 degreeC conditions is 100 mPa * S or less.

  Fatty acid esters that are not liquid under the conditions of 1 atm and 20 ° C. need to be heated and stirred for a long time in order to mix with the substituted succinic anhydride, or even if mixed uniformly with the substituted succinic anhydride. Inconvenience that the fatty acid ester is likely to be precipitated as a solid during storage under atmospheric pressure and 20 ° C, or that the emulsion of the mixture of the substituted succinic anhydride and the fatty acid ester is likely to be unstable and causes aggregation or separation. Therefore, the object of the present invention cannot be achieved. In addition, diesters and triesters (oils and fats) that are fatty acid esters not having the structural formula of the above formula (1) have a disadvantage that hydrolysis of the substituted succinic anhydride is fast, and stains are likely to occur in the papermaking system. The subject of this invention cannot be achieved.

  The fatty acid ester is an ester of a saturated fatty acid and an alkyl alcohol. As the saturated fatty acid, caproic acid (6 carbon atoms), enanthic acid (7 carbon atoms), caprylic acid (8 carbon atoms), pelargonic acid (9 carbon atoms), capric acid (10 carbon atoms), undecanoic acid (11 carbon atoms) ), Lauric acid (12 carbon atoms), tridecanoic acid (13 carbon atoms), myristic acid (14 carbon atoms), pentadecylic acid (15 carbon atoms), palmitic acid (16 carbon atoms), margaric acid (17 carbon atoms), Examples include stearic acid (18 carbon atoms), isostearic acid (18 carbon atoms), tuberculostearic acid (19 carbon atoms), arachidic acid (20 carbon atoms), and behenic acid (22 carbon atoms). As unsaturated fatty acid esters, caproleic acid (carbon number 10), Linderic acid (carbon number 12), myristoleic acid (carbon number 14), palmitoleic acid (carbon number 16), olei List acids (18 carbon atoms), linoleic acid (18 carbon atoms), linolenic acid (18 carbon atoms), eicosenoic acid (20 carbon atoms), cetreic acid (22 carbon atoms), erucic acid (22 carbon atoms), etc. Can do. Among these, fatty acids having 8 to 18 carbon atoms such as caprylic acid (8 carbon atoms), capric acid (10 carbon atoms), lauric acid (12 carbon atoms), myristic acid (14 carbon atoms), palmitic acid (carbon) 16), stearic acid (18 carbon atoms), oleic acid (18 carbon atoms) and linoleic acid (18 carbon atoms) are preferable. Examples of the alkyl alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, isopentyl alcohol, 2- Methylbutyl alcohol, 1-methylbutyl alcohol, neopentyl alcohol, 1,2-dimethylpropyl alcohol, 1-ethylpropyl alcohol, n-hexyl alcohol, 4-methylpentyl alcohol, 3-methylpentyl alcohol, 2-methylpentyl alcohol 1-methylpentyl alcohol, 3,3-dimethylbutyl alcohol, 2,2-dimethylbutyl alcohol, 1,1-dimethylbutyl alcohol, 1,2-di Tylbutyl alcohol, 1,3-dimethylbutyl alcohol, 2,3-dimethylbutyl alcohol, 2-ethylbutyl alcohol, 1-ethylbutyl alcohol, 1-ethyl-1-methylpropyl alcohol, n-heptyl alcohol, n-octyl Alkyl alcohols such as alcohol, 2-ethylhexyl alcohol, n-nonyl alcohol, n-decyl alcohol, n-undecyl alcohol, n-dodecyl alcohol, n-tridecyl alcohol, n-tetradecyl alcohol and n-pentadecyl alcohol; An alkyl alcohol having 4 to 16 carbon atoms is preferable.

  When these fatty acid esters are mixed with a substituted succinic anhydride, they can be uniformly mixed with a gentle stirring for a short time, and even when the mixture is stored at 25 ° C., it can be kept in a uniform state over a long period of time. Furthermore, it is preferable because there is an advantage that the storage stability of an emulsion of a mixture of a substituted succinic anhydride and a fatty acid ester is excellent.

  The sizing agent composition of the present invention is obtained by emulsifying a mixture obtained by mixing the above (A) fatty acid ester and the above (B) substituted succinic anhydride at a specific ratio. The mixing ratio of the fatty acid ester and the substituted succinic anhydride is in the range of fatty acid ester: substituted succinic anhydride = 50: 50 to 10:90 by mass ratio. When there are more fatty acid esters than the above range, the size effect is inferior to the case of the substituted succinic anhydride alone, and when the fatty acid ester is less than the above range, the size effect, stability of the emulsion and soil reduction in papermaking systems are reduced. This is not preferable because no effect is observed.

  The fatty acid ester and the substituted succinic anhydride in the present invention are excellent in compatibility with each other and can be mixed at any temperature condition as long as both are liquid, but it is preferable to mix by heating at 100 ° C. or lower. When the temperature is higher than 100 ° C., there is a risk of discoloration due to alteration due to heat or a decrease in the effect as a sizing agent. In addition, when mixing, both substituted succinic anhydride and fatty acid ester do not contain moisture such as dry air, nitrogen or argon to prevent hydrolysis or modification with moisture in the air during stirring. It is preferable to mix under an atmosphere.

  The sizing composition of the present invention is preferably used as a water-dispersible sizing agent in which at least the fatty acid ester and the substituted succinic anhydride are dispersed in water from the viewpoint of workability. The water-dispersible sizing agent can be prepared by emulsifying and dispersing by a known emulsification method using a surfactant or various aqueous polymer dispersants as necessary. The preparation of the water dispersible sizing agent is to disperse the sizing composition in water immediately before use or to continuously emulsify with a pump for the purpose of minimizing performance degradation due to hydrolysis of the substituted succinic anhydride. It is preferable to prepare a water dispersible sizing agent and use it continuously.

  In the present invention, it is preferable to emulsify a mixture obtained by further mixing a surfactant with a mixture of a substituted succinic anhydride and a fatty acid ester, because the emulsifiability is improved and dirt is not easily attached to the papermaking tool. As described above, the amount of the surfactant added to the mixture of the substituted succinic anhydride and the fatty acid ester (hereinafter sometimes abbreviated as a surfactant for mixing) is the amount of the substituted succinic anhydride and the fatty acid ester. 0.01-10 mass parts is preferable with respect to a total of 100 mass parts, and 0.05-5 mass parts is more preferable. If the amount of the surfactant for mixing is too large, the mixture will easily absorb moisture in the air during storage of the mixture of the substituted succinic anhydride, fatty acid ester and surfactant. Degradation may be accelerated, and the substituted succinic acid, which is a hydrolyzate, may cause soiling of the papermaking tool and decrease in size performance. If the amount of the surfactant for mixing is too small, the above-mentioned advantage of mixing the surfactant for mixing into the mixture of substituted succinic anhydride and fatty acid ester may not be sufficiently exhibited.

  Examples of the surfactant for mixing include conventionally known cationic surfactants, amphoteric surfactants, anionic surfactants and nonionic surfactants. As the surfactant for mixing, one or more of these may be used.

  Examples of the cationic surfactant include a long-chain alkylamine salt, a modified amine salt, a tetraalkyl quaternary ammonium salt, a trialkylbenzyl quaternary ammonium salt, an alkylpyridinium salt, an alkylquinolium salt, and an alkylsulfonium salt. It is done.

  Examples of the amphoteric surfactant include various betaine surfactants.

  Examples of the anionic surfactant include alkyl sulfonates, alkyl sulfates, alkyl phosphates, polyoxyalkylene alkyl sulfates, polyoxyalkylene alkylaryl sulfates, polyoxyalkylene aralkyl aryl sulfates. , Alkyl-aryl sulfonates, polyoxyalkylene alkyl phosphates, and various sulfosuccinate surfactants.

  Examples of the nonionic surfactant include fatty acid sorbitan ester and its polyalkylene oxide adduct, fatty acid polyglycol ester, various polyalkylene oxide type nonionic surfactants (polyoxyethylene fatty acid ester, polyoxyethylene fatty acid amide, polyoxy Ethylene aliphatic amine, polyoxyethylene aliphatic mercaptan, polyoxyethylene alkylaryl ether, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene aralkyl aryl ether, polyoxyethylene distyrenated phenol ether phosphate, etc.) It is done.

  Among these, anionic surfactants and nonionic surfactants are preferred, and specifically, sulfosuccinic acid dialkyl sodium salts or polyoxyalkylene alkyl ether phosphates are preferred.

  The mixing surfactant may be mixed at the same time when the substituted succinic anhydride and the fatty acid ester are mixed, or may be continuously mixed into the mixture of the substituted succinic anhydride and the fatty acid ester immediately before emulsification. It is preferable to mix with a mixture of a substituted succinic anhydride and a fatty acid ester.

  When obtaining a sizing composition by emulsification in the present invention, it is preferable to use an aqueous polymer dispersing agent because the dispersion stability of the sizing composition which is an emulsion is excellent.

  Examples of the aqueous polymer dispersant include various water-soluble synthetic polymers and natural polymers. Specifically, starches, acrylamide polymers, starch graft acrylamide polymers, polyvinyl alcohols, carboxymethyl celluloses, Examples include gums and casein. Among these, starches, acrylamide polymers, starch graft acrylamide polymers, carboxymethyl celluloses, and polyvinyl alcohols are preferable.

  The weight average molecular weight of the aqueous polymer dispersant is preferably 10,000 or more and 10,000,000 or less. If the weight average molecular weight is less than 10,000, the emulsifiability and dispersion stability may be reduced. When the weight average molecular weight is larger than 10,000,000, the viscosity of the aqueous polymer dispersant increases, which may make handling difficult.

  As the starch, for example, raw starch such as corn, wheat, potato, rice, tapioca, waxy corn, etc., and those starches selected from the group consisting of primary, secondary and tertiary amino groups and quaternary ammonium groups And cationic starch containing at least one kind of basic nitrogen. Also, amphoteric starch obtained by introducing an anionic group (for example, phosphate group) into the cationic starch can be used. Other examples include oxidized starch, dialdehyde starch, alkyl etherified starch, phosphate starch, urea phosphate starch, and hydrophobically modified starch.

  Examples of the acrylamide polymers include water-soluble polymers containing acrylamide and / or methacrylamide, that is, (meth) acrylamide of 50 mol% or more and may have a cationic group and / or an anionic group. . This acrylamide polymer can be obtained, for example, by a modification method in which an ionic group is introduced by modifying a water-soluble polymer containing (meth) acrylamide as a main component, or (meth) acrylamide and, if necessary, a cationic monomer or anion. It can be obtained by a copolymerization method in which a monomer mixture containing a polymerizable monomer and another vinyl monomer is polymerized by a conventionally known method, or by a combination of both methods.

  In the case of the modification method, the Hoffman modification reaction, the Mannich reaction, and the amide exchange reaction with a polyamine are used for the introduction of the cationic group into the water-soluble polymer, while the anionic group is introduced into the water-soluble polymer. Hydrolysis reaction can be used.

  Examples of the cationic monomer include mono- or di-alkylaminoalkyl acrylate, mono- or di-alkylaminoalkyl methacrylate, mono- or di-alkylaminoalkyl methacrylamide, vinyl pyridine, vinyl imidazole, mono- or di-allylamine. And mixtures thereof, and quaternary ammonium salts thereof.

  Examples of the anionic monomer include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid, and various other known polymerizable monomers having a sulfonic acid group or a phosphoric acid group. Can be exemplified.

  Examples of the other vinyl monomers include cross-linkable vinyl monomers such as N-methylolacrylamide, methylene (bis) acrylamide, bifunctional monomer, trifunctional monomer, and tetrafunctional monomer that can be copolymerized with (meth) acrylamide. Also, nonionic vinyl monomers such as (meth) acrylic acid ester, styrene, and vinyl acetate can be used in combination.

  The acrylamide polymers can be produced by various conventionally known methods. For example, a reaction vessel equipped with a stirrer and a nitrogen gas introduction tube is charged with vinyl monomer and water as constituents, and as a polymerization initiator, peroxide such as hydrogen peroxide, ammonium persulfate, potassium persulfate, ammonium hydroperoxide, etc. Or any redox initiator consisting of a combination of these peroxides and a reducing agent such as sodium bisulfite, and further a water-soluble azo such as 2,2′-azobis (2-aminopropane) dihydrochloride Acrylamide polymers can be obtained by reacting at a reaction temperature of 40 to 95 ° C. for 1 to 5 hours using a system initiator or the like.

  The starch graft acrylamide polymer is prepared by graft polymerization of monomers capable of forming the acrylamide polymer in the presence of starch.

  For example, it can be obtained by copolymerizing a monomer mixture containing (a) a cationic group-containing monomer, (b) an anionic group-containing monomer, and (c) (meth) acrylamide in an aqueous cationic starch solution.

  Specific examples of the cationic group-containing monomer (a) include mono- or di-alkylaminoalkyl acrylate, mono- or di-alkylaminoalkyl methacrylate, mono- or di-alkylaminoalkyl acrylamide, mono- or di- -Alkylaminoalkyl methacrylamide, vinyl pyridine, vinyl imidazole, mono- or di-arylamines and mixtures thereof, and quaternary ammonium salts thereof can be exemplified. As the anionic group-containing monomer (b), in addition to α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, a known sulfonic acid group and phosphoric acid group are known. These various polymerizable monomers can be used. The above modification and copolymerization reactions follow known reaction procedures, and appropriate reaction conditions can be arbitrarily selected.

  As other water-soluble polymers, carboxymethyl celluloses, polyvinyl alcohols, dextrins, chitosans and the like can also be used.

  The concentration and addition amount of the aqueous polymer dispersant are not particularly limited, and the addition amount and concentration can be changed according to the use, but it is 0 with respect to the total mass of the fatty acid ester and the substituted succinic anhydride. It is preferable to add 1 to 4 times.

  Furthermore, when obtaining a sizing composition by emulsification, it is preferable to use a surfactant in combination with the aqueous polymer dispersant because the emulsifiability of the sizing composition and the stability of the obtained emulsion are further improved.

  Examples of the surfactant used in obtaining a sizing composition by emulsification (hereinafter sometimes referred to as an emulsifying surfactant) include the above-mentioned conventionally known cationic surfactants, anionic surfactants, and amphoteric interfaces. Mention may be made of activators and nonionic surfactants. One or more of these surfactants for emulsification may be used.

  Among the surfactants, nonionic surfactants and anionic surfactants are preferable as the surfactant for emulsification of the present invention.

  The concentration and addition amount of the surfactant for emulsification are not particularly limited, and the addition amount and concentration can be changed according to the use, but the ratio to the total of the fatty acid ester and the substituted succinic anhydride is 0. It is preferable to use 3 to 3% by mass because the emulsifiability of the sizing agent composition and the stability of the obtained emulsion are improved.

  The surfactant for emulsification may be mixed with the aqueous polymer dispersant in advance, or may be continuously mixed with the aqueous polymer dispersant at the time of emulsification. Is preferred.

  As an emulsifier, dispersion of the sizing composition from the substituted succinic anhydride and fatty acid ester contained in the sizing composition of the present invention, a surfactant used as necessary, various aqueous polymer dispersants and water. There is no particular limitation as long as the liquid can be prepared. Various emulsifiers or emulsifiers such as a static mixer, a venturi mixer, a blender, a homomixer, a high-pressure / high-speed discharge homogenizer, an ultrasonic emulsifier, and a high shear rotary emulsifier. The device is ready for use.

  The sizing composition of the present invention can be used for either an internally added sizing composition or a surface sizing composition.

  When the sizing composition of the present invention is used as an internal sizing composition, the amount of the sizing composition added to the pulp slurry per active ingredient based on the dry weight of the pulp is preferably 0.005 to 5% by mass, preferably Is 0.01 to 2% by mass. The active ingredient in this invention is the total of the fatty acid ester and substituted succinic anhydride represented by the structural formula of formula (1).

  The papermaking system in the present invention includes pulp, dilution water, and additives that are added as necessary, for example, fillers, dyes, sizing agents, dry paper strength improvers, wet paper strength improvers, yield improvers, pitch control agents. Etc. are mixed with a pulp slurry.

  In the production of paper and paperboard using the sizing composition of the present invention, pulp raw materials include bleached kraft pulp, sulfite pulp, or unbleached chemical pulp, groundwood pulp, mechanical pulp, and thermomechanical pulp. Alternatively, any of waste paper pulp such as unbleached high-yield pulp, newspaper waste paper, magazine waste paper, corrugated waste paper, and deinked waste paper can be used.

  In order to obtain paper using the sizing composition of the present invention, additives such as filler, dye, aluminum sulfate, dry paper strength improver, wet paper strength improver, yield improver, drainage improver, etc. In order to realize the physical properties required for the paper type, it may be used as necessary. As the filler, heavy or light calcium carbonate is mainly used, but clay and talc are also used, and these may be used in combination. Examples of dry paper strength improvers include anionic polyacrylamide polymers, cationic polyacrylamide polymers, and amphoteric polyacrylamide polymers (each of which is a copolymer of (meth) acrylamide and other vinyl monomers, and so on). , Cationized starch, amphoteric starch and the like, and these may be used alone or in combination. Examples of the wet paper strength improver include polyamide and epichlorohydrin resins. These may be used alone or in combination with an anionic polyacrylamide polymer. Examples of the yield improver include an anionic or cationic high molecular weight polyacrylamide polymer, a combined use of silica gel and cationized starch, and a combined use of bentonite and a cationic high molecular weight polyacrylamide polymer.

When the sizing composition of the present invention is used as a surface sizing composition, the coating amount of the active ingredient of the sizing composition on the paper surface is 0.001 to 5 g / m ² , preferably 0.002. ˜1 g / m ² . A size press, a gate roll coater, a rod metering coater, a bill blade coater, a calendar or the like is used for the coating apparatus.

  When the sizing composition of the present invention is used as a surface sizing composition and applied to the surface of paper, starches such as oxidized starch, phosphate esterified starch, enzyme-modified starch, cationized starch and amphoteric starch, Celluloses such as carboxymethyl cellulose, polyvinyl alcohols, polyacrylamides, water-soluble polymers such as sodium alginate, inorganic salts such as sodium chloride and sodium sulfate, and the like can also be mixed and used. Also, other surface sizing agents, anti-slip agents, antiseptics, rust inhibitors, antifoaming agents, viscosity modifiers, dyes, pigments, and other additives can be used in combination.

  The paper to which the sizing composition of the present invention is applied is not particularly limited, and examples thereof include various papers and paperboard.

  When making recycled paper containing high-quality paper, medium-quality paper, deinked pulp, and various other used paper pulp using calcium carbonate, the papermaking apparatus is easily soiled, and the sizing composition of the present invention is particularly effective. .

  The types of paper include milk carton base paper, cup base paper and other liquid container base paper, photographic paper base paper, gypsum board base paper, PPC paper, inkjet printing paper, laser printer paper, foam paper, thermal transfer paper, pressure-sensitive paper, Recording paper such as heat-sensitive recording paper and pressure-sensitive recording paper, and its base paper, art paper, coated paper such as cast coated paper, high-quality coated paper, wrapping paper such as kraft paper, pure white roll paper, other notebook paper, book paper, various types Examples include various papers (Western paper) such as printing paper and newspaper, paperboards for paper containers such as Manila balls, white balls, and chip balls, and paperboards such as liners.

  Especially, paper types that require edge wick sizing such as milk carton base paper, cup base paper and other liquid container bases, photographic paper base paper, and paper types that require strong sizing such as gypsum board base paper In this papermaking, the sizing agent is added to the pulp slurry at a high rate of 0.2% by mass or more as an active ingredient with respect to the weight of the absolutely dry pulp. Therefore, the papermaking apparatus is easily soiled, and the present invention is effective.

Next, the board | substrate manufacturing method of this invention using the sizing agent composition of this invention mentioned above is demonstrated.
The method for producing the paperboard of the present invention comprises:
(1) pH is 6.5 to 8.5
(2) Alkalinity is 50 to 400 ppm, and (3) Conductivity is 50 to 250 mS / m.
To the pulp slurry,
(4) Paper is made by adding the sizing composition according to the present invention.
By satisfying all these conditions, it is possible to avoid scale troubles and pitch troubles by reducing the occurrence of stains in the papermaking system, and it is possible to provide a paperboard manufacturing method that is excellent in size effect.

<Paperboard>
Examples of the paperboard in the present invention include liner base paper, core base paper, paper tube base paper, gypsum board base paper, coated white board, uncoated white board, chip ball and the like. Of these, core base paper and liner base paper are preferable, and liner base paper is particularly preferable.

<Pulp slurry>
Pulp slurry is a slurry of pulp raw material. As raw materials for pulp, bleached or unbleached chemical pulp such as kraft pulp or sulfite pulp, bleached or unbleached high-yield pulp such as mechanical pulp or thermomechanical pulp, Kamihaku waste paper, newspaper waste paper, magazine waste paper, cardboard Any waste paper pulp such as waste paper or deinked waste paper can be used, and it is preferable to use 50% or more of waste paper pulp. Moreover, as said pulp raw material, the mixture of the said pulp raw material and polyamide, polyester, polyolefin, etc. can also be used. Furthermore, a filler is a main raw material used for pulp slurry. Examples of the filler include calcium carbonate, clay, talc, chalk, titanium oxide, and white carbon.

  The values of pH, alkalinity, and conductivity in the present invention are values obtained by measuring a pulp slurry immediately before forming a sheet, particularly a paperboard. Specifically, for example, it is a measured value of pH, alkalinity, and conductivity of pulp slurry in an ultraformer or a long net inlet or a pulp slurry in a round net vat.

  The pulp slurry has a pH of 6.5 to 8.5, preferably 6.6 to 8.2, and more preferably 6.7 to 8.0. The pH in the present invention is a value measured under the condition of 25 ° C. In order to adjust the pH of the pulp slurry to the above range, a pH adjuster, for example, an alkaline substance such as sodium hydroxide or sodium bicarbonate, or an acidic substance such as sulfuric acid is used so that the conductivity and alkalinity do not depart from the above range. It is good to add.

The alkalinity of the pulp slurry is 50 to 400 ppm, preferably 70 to 400 ppm, and more preferably 80 to 300 ppm. In the present invention, the alkalinity is determined by using a part of the pulp slurry immediately before papermaking, No. An indicator of ethanol solvent mixed with methyl red and bromocresol green is added to the filtrate obtained by suction filtration with 5A filter paper (manufactured by Toyo Filter Paper Co., Ltd.), and the filtrate is stirred while gently stirring the liquid. Titration is performed using 1 / 50N sulfuric acid until the color changes from blue to red, and the alkalinity amount in the filtrate is converted to calcium carbonate to determine the alkalinity (mg CaCO ₃ / l). Is a value determined by the formula of titration (ml) × 1000 / filtrate (ml). In order to adjust the alkalinity of the pulp slurry to the above range, an alkaline substance such as sodium hydrogen carbonate or calcium carbonate is preferably added so that the pH and alkalinity do not deviate from the above range.

  The conductivity of the pulp slurry is 50 to 250 mS / m, preferably 50 to 200 mS / m, and more preferably 50 to 150 mS / m. The conductivity in the present invention is a value measured under the condition of 25 ° C.

  In the paperboard manufacturing method of the present invention, papermaking is performed by adding the sizing composition according to the present invention to the pulp slurry. The sizing agent composition is preferably a water-dispersible sizing agent that is dispersed in water as described above. As described above, the paperboard production method of the present invention performs papermaking by adding the sizing composition according to the present invention to pulp slurry having pH, alkalinity, and electrical conductivity within specific ranges. By reducing the occurrence of contamination in the system, scale troubles and pitch troubles can be prevented, and a paperboard excellent in size effect can be provided.

  In addition, a known sizing agent such as a 2-oxetanone sizing agent, a rosin sizing agent, or a cationic synthetic sizing agent can be used in combination with the sizing agent composition as long as the effects of the present invention are not impaired. .

  The 2-oxetanone sizing agent is a sizing agent mainly composed of a 2-oxetanone compound among active ingredients as a sizing agent. The 2-oxetanone compound includes an alkyl having a basic structure represented by the following formula (2) and It is a general term for alkenyl ketene dimers and / or alkyl and / or alkenyl ketene multimers having the basic structure of the following formula (3).

（但し、式（２）中のＲ^３、Ｒ^４は、８〜２４個の炭素原子を有する飽和又は不飽和のアルキル基又はアルケニル基を示し、Ｒ^３とＲ^４とは同一であっても異なっていてもよい。）

(However, R ³ and R ⁴ in Formula (2) represent a saturated or unsaturated alkyl group or alkenyl group having 8 to 24 carbon atoms, and R ³ and R ⁴ may be the same. May be different.)

（但し、式（３）中、ｎは自然数であり、通常１〜１０であり、Ｒ^５及びＲ^７は８〜２４個の炭素原子を有する飽和又は不飽和のアルキル基又はアルケニル基であり、Ｒ^６は４〜４０個の炭素原子を有する飽和又は不飽和のアルキル基又はアルケニル基であり、Ｒ^３とＲ^４とＲ^５とは同一であっても異なっていてもよい。）

(In the formula (3), n is a natural number, usually 1 to 10, R ⁵ and R ⁷ are a saturated or unsaturated alkyl group or alkenyl group having 8 to 24 carbon atoms, R ⁶ is a saturated or unsaturated alkyl or alkenyl group having 4 to 40 carbon atoms, and R ³ , R ⁴ and R ⁵ may be the same or different.

  The 2-oxetanone sizing agent can be used in the form of an emulsion by dispersing the 2-oxetanone compound using an emulsifier by a conventionally known method. Examples of the dispersant include cationic dispersants such as cationized starch and cationic polymer, and anionic dispersants having a sulfonic acid group or a sulfate group and salts thereof. One or more of these dispersants can be mixed and used. Moreover, there is no restriction | limiting in particular as the emulsification method, A conventionally well-known method can be applied, For example, emulsification methods, such as inversion emulsification, solvent emulsification, forced emulsification, can be used.

  There is no restriction | limiting in particular as said rosin-type sizing agent, A conventionally well-known thing can be used. For example, as the rosin-based substance, (A) rosins and / or α, β-unsaturated carboxylic acid-modified rosins of rosins, (B) rosin esters obtained by esterification reaction of rosins and / or The α, β-unsaturated carboxylic acid-modified rosin esters of the rosin esters can be used in any combination. A rosin emulsion sizing agent obtained by emulsifying and dispersing these rosin substances in water by a conventionally known method can be used. A solution rosin can also be used.

  As the cationic synthetic sizing agent, known ones can be used. For example, as described in JP-A-2001-262495, a quaternized product of a styrene-acrylic ester copolymer can be used. . This is a cation monomer obtained by polymerizing a styrene monomer, an acrylate monomer containing a tertiary amino group such as dimethylaminoethyl methacrylate, and a monomer copolymerizable with these monomers. It is produced by a method in which a quaternizing agent such as epihalohydrin is reacted.

  Examples of the styrenic monomer include styrene, α-methylstyrene, vinyltoluene, and divinylbenzene. These monomers can be used singly or in combination. Among these monomers, styrene is preferable because it is easily available and inexpensive.

  Examples of the acrylate monomer containing a tertiary amino group include (monoalkyl or dialkyl) aminoalkyl (meth) acrylate, (monoalkyl or dialkyl) aminohydroxylalkyl (meth) acrylate, and the like. These 1 type (s) or 2 or more types can be used. Among these monomers, dimethylaminoethyl methacrylate is preferable because it is easily available and inexpensive.

  Examples of the monomer copolymerizable with these monomers used as necessary include hydrophobic monomers other than styrene monomers, and cationic monomers other than acrylic acid ester monomers containing tertiary amino groups. .

  Examples of the hydrophobic monomer other than the styrene monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) ) Cyclic alkyl (meth) acrylates such as alkyl (meth) acrylates having 1 to 18 carbon atoms such as acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, maleic acid, and dialkyl diesters of fumaric acid , Vinyl esters such as vinyl acetate and vinyl propionate, N-alkyl (meth) acrylamides, and methyl vinyl ether, and one or more of these monomers can be used.

  Examples of the cationic monomer other than the acrylate-based monomer containing a tertiary amino group include (monoalkyl or dialkyl) aminoalkyl (meth) acrylamide, vinylpyridine, vinylimidazole, and the like. 1 type (s) or 2 or more types can be used.

  Examples of the quaternizing agent include methyl halide, ethyl chloride, benzyl chloride, epichlorohydrin, glycidyl trimethyl ammonium chloride, and organic halides such as 3-chloro-2-hydroxypropyltrimethyl ammonium chloride, dimethyl sulfate, and Examples thereof include dialkyl sulfuric acid such as diethyl sulfuric acid.

  Polymerization of the cationic copolymer may be performed by, for example, mixing a mixture of the styrene monomer and an acrylate ester monomer containing a tertiary amino group and, if necessary, a mixture of other copolymerizable vinyl monomers. In a lower alcohol organic solvent such as methyl alcohol, ethyl alcohol or isopropyl alcohol or an oily organic solvent such as benzene, toluene or xylene, or in a mixture of these lower alcohol organic solvent and water, Can be polymerized in water at 60 to 120 ° C. for 1 to 10 hours using a radical polymerization catalyst.

<Paper strength agent>
In the paperboard manufacturing method of the present invention, a paper strength agent can be added to the pulp slurry. Examples of the paper strength agent include acrylamide polymers, starches, polyvinyl alcohols, and celluloses. Among these, acrylamide polymers and / or starches are preferable.

  Acrylamide polymers are required for homopolymer or copolymer (meth) acrylamide polymers obtained by polymerizing (meth) acrylamide and / or ionic vinyl monomers, and (meth) acrylamide and / or ionic vinyl monomers. (Meth) acrylamide polymer obtained by adding other monomers depending on the polymer, starch-grafted polyacrylamide polymer obtained by polymerizing acrylamide monomers in the presence of starch, Hoffmann decomposition reaction A cation-modified (meth) acrylamide polymer by, and an acrylamide polymer by Mannich modification.

  (Meth) acrylamide means acrylamide or methacrylamide, which can be used in powder or aqueous solution.

  The ionic vinyl monomer is a cationic vinyl monomer and / or an anionic vinyl monomer.

  Examples of the cationic vinyl monomer include a vinyl monomer having a primary amino group, a vinyl monomer having a secondary amino group, a vinyl monomer having a tertiary amino group, and a vinyl monomer having a quaternary ammonium salt.

  Examples of the vinyl monomer having a primary amino group include allylamine, methallylamine, and salts thereof. These salts include inorganic acid salts such as hydrochloride and sulfate, and organic acid salts such as formate and acetate.

  Examples of the vinyl monomer having a secondary amino group include diallylamine, dimethallylamine, and salts thereof. These salts include inorganic acid salts such as hydrochloride and sulfate, and organic acid salts such as formate and acetate.

  Further, as the vinyl monomer having a secondary amino group, vinyl monomers having the primary amino group such as allylamine and methallylamine, and alkyl halides such as methyl chloride and methyl bromide, benzyl chloride, and benzyl bromide are used. Examples thereof include monomers converted into secondary amine acid salts by reaction with aralkyl halides, dimethyl sulfate, dialkyl sulfates such as diethyl sulfate, epichlorohydrin and the like.

  Examples of the vinyl monomer having a tertiary amino group include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, diethylaminopropyl acrylate, and diethylaminopropyl methacrylate. And dialkylaminoalkyl (meth) acrylamides such as dialkylaminoalkyl (meth) acrylates, dimethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide, diethylaminopropyl acrylamide, and diethylaminopropyl methacrylamide, and salts thereof. it can. These salts include inorganic acid salts such as hydrochloride and sulfate, and organic acid salts such as formate and acetate.

  Further, as the vinyl monomer having a tertiary amino group, vinyl monomers having the secondary amino group such as diallylamine and dimethallylamine, and alkyl halides such as methyl chloride and methyl bromide, aralkyl such as benzyl chloride and benzyl bromide. Examples thereof include monomers converted into acid salts of tertiary amines by reaction with any one of halides, alkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epichlorohydrin.

  Examples of the vinyl monomer having a quaternary ammonium salt include diallyldimethylammonium chloride, dimethallyldimethylammonium chloride, diallyldiethylammonium chloride, and diethyldimethallylammonium chloride.

  Examples of the vinyl monomer having a quaternary ammonium salt include a vinyl monomer obtained by reacting the vinyl monomer having a tertiary amino group with a quaternizing agent. Examples of the quaternizing agent include alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, alkyl sulfates such as dimethyl sulfate and diethyl sulfate, epichlorohydrin, 3-chloro- Examples include 2-hydroxypropyltrimethylammonium chloride and glycidyltrialkylammonium chloride.

  Specific examples of the quaternary ammonium salts include acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride, acryloyloxypropyldimethylbenzylammonium chloride, and methacryloyl. Examples thereof include oxypropyldimethylbenzylammonium chloride.

  As a cationic vinyl monomer that polymerizes with (meth) acrylamide to form a (meth) acrylamide polymer, vinyl monomers having these primary amino group, secondary amino group, tertiary amino group, or quaternary ammonium salt are used. You may use individually by 1 type and may use 2 or more types together.

  Examples of the anionic vinyl monomer include a carboxyl group-containing polymerizable vinyl monomer (which means a polymerizable vinyl monomer containing a carboxyl group), a sulfonic acid group-containing polymerizable vinyl monomer (which is a sulfonic acid group). And a phosphoric acid group-containing polymerizable vinyl monomer (this means a polymerizable vinyl monomer containing a phosphoric acid group).

  Examples of the carboxyl group-containing polymerizable vinyl monomer include glyoxyls such as unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, cinnamic acid, and crotonic acid, 2-acrylamide glycolic acid, and 2-methacrylamide glycolic acid. Unsaturated dicarboxylic acids such as acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, and muconic acid, aconitic acid, 3-butene-1,2,3-tricarboxylic acid, and 4-pentene-1,2,4 Unsaturated tricarboxylic acids such as tricarboxylic acids, 1-pentene-1,1,4,4-tetracarboxylic acid, 4-pentene-1,2,3,4-tetracarboxylic acid, and 3-hexene-1,1 And unsaturated tetracarboxylic acids such as 6,6-tetracarboxylic acid.

  Examples of the sulfonic acid group-containing polymerizable vinyl monomer include vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid.

  Examples of the phosphoric acid group-containing polymerizable vinyl monomer include vinylphosphonic acid and 1-phenylvinylphosphonic acid.

  In addition, salts of carboxyl group-containing polymerizable vinyl monomers, sulfonic acid group-containing polymerizable vinyl monomers, and phosphoric acid group-containing polymerizable vinyl monomers can also be used. Examples of the carboxyl group-containing monomer, the sulfonic acid group-containing monomer, or the salt of the phosphoric acid group-containing monomer include alkali metal salts, alkaline earth metal salts, and ammonium salts.

  As anionic vinyl monomers that polymerize with (meth) acrylamide to form (meth) acrylamide polymers, these carboxyl group-containing polymerizable vinyl monomers, sulfonic acid group-containing polymerizable vinyl monomers, and phosphoric acid group-containing polymerizable vinyl monomers And these salts may be used individually by 1 type, and may use 2 or more types together.

  Among the anionic vinyl monomers, a suitable anionic vinyl monomer is an unsaturated dicarboxylic acid, more preferably itaconic acid.

  Crosslinkable monomers and crosslinkable compounds that are one of the other monomers include monomers having multiple vinyl groups, N-substituted (meth) acrylamide, monomers having a chain transfer point with vinyl groups, silicon monomers , Water-soluble aziridinyl compounds, water-soluble polyfunctional epoxy compounds, and the like. These may be used alone or in combination of two or more.

  Examples of the monomer having a plurality of vinyl groups include trifunctional vinyl monomers, tetrafunctional vinyl monomers and the like in addition to bifunctional monomers such as di (meth) acrylates, bis (meth) acrylamides, and divinyl esters. Can be mentioned.

  Examples of the di (meth) acrylates include ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol diacrylate. A methacrylate, glycerol diacrylate, glycerol dimethacrylate, etc. can be mentioned, These may be used individually by 1 type and may use 2 or more types together.

  Examples of the bis (meth) acrylamides include N, N-methylenebisacrylamide, N, N-methylenebismethacrylamide, ethylenebisacrylamide, ethylenebismethacrylamide, hexamethylenebisacrylamide, hexamethylenebismethacrylamide, N, N-bisacrylamide acetic acid, N, N-bisacrylamide methyl acetate, N, N-benzylidenebisacrylamide, N, N-bis (acrylamidomethylene) urea and the like can be mentioned, and these may be used alone. Two or more kinds may be used in combination.

  Examples of the divinyl esters include divinyl adipate, divinyl sebacate, diallyl phthalate, diallyl malate, and diallyl succinate. These may be used alone or in combination of two or more. You may use together.

  Examples of other bifunctional monomers include allyl acrylate, allyl methacrylate, divinylbenzene, and diisopropenylbenzene. These may be used alone or in combination of two or more. May be.

  Examples of the trifunctional vinyl monomer include triacryl formal, triallyl isocyanurate, N, N-diallylacrylamide, N, N-diallylmethacrylamide, triallylamine, and triallyl pyromellitate. These may be used alone or in combination of two or more.

  Examples of the tetrafunctional vinyl monomer include tetramethylolmethane tetraacrylate, tetraallyl pyromellitate, N, N, N ′, N′-tetraallyl-1,4-diaminobutane, tetraallylamine (salt), and tetra An allyloxyethane etc. can be mentioned, These may be used individually by 1 type and may use 2 or more types together.

  Examples of the N-substituted (meth) acrylamide include N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl ( Mention may be made of (meth) acrylamide and Nt-octyl (meth) acrylamide.

  Examples of the monomer having a crosslinking action by having a vinyl group and a chain transfer point include N-methylolacrylamide, glycidyl acrylate, and glycidyl methacrylate, and these may be used alone. Two or more kinds may be used in combination.

  Examples of the silicon monomer include 3-acryloyloxymethyltrimethoxysilane, 3-methacryloyloxymethyltrimethoxysilane, 3-acryloyloxypropyldimethoxymethylsilane, 3-methacryloyloxypropyldimethoxymethylsilane, 3 -Acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropylmethyldichlorosilane, 3-methacryloyloxypropylmethyldichlorosilane, 3-acryloyloxyoctadecyltriacetoxysilane, 3 -Methacryloyloxyoctadecyltriacetoxysilane, 3-acryloyloxy-2,5-dimethylhexyldiacetoxymethylsilane, 3-methacryloyloxy-2,5-dimethylhex Luzia Seto carboxymethyl silane, and it can be exemplified vinyl dimethylacetoxysilane like, which may be used singly or in combination of two or more.

  Examples of the water-soluble aziridinyl compound include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, and 4,4′-bis (ethyleneimine). And carbonylamino) diphenylmethane. These may be used alone or in combination of two or more.

  Examples of the water-soluble polyfunctional epoxy compound include (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, and (poly) glycerin triglycidyl ether. These may be used alone or in combination of two or more.

  Other monomers that can be used when synthesizing the (meth) acrylamide polymer include nonionic vinyl monomers. Examples of nonionic vinyl monomers include (meth) acrylic acid esters, (meth) acrylonitrile, styrene, styrene derivatives, vinyl acetate, vinyl propionate, methyl vinyl ether, N- (2-hydroxyethyl) acrylamide, and the like. These may be used alone or in combination of two or more.

  The amount of each monomer constituting the (meth) acrylamide polymer is determined by the internal bond strength and burst strength of the paper when the paper strength agent containing the resulting (meth) acrylamide polymer is used. It is possible to determine the paper strength such as the degree, and the performance such as the yield of paper drainage, fine fiber, filler and the like at the time of paper making.

  The monomer constituting the (meth) acrylamide polymer must be (meth) acrylamide and an ionic vinyl monomer, and the total amount of these monomers and other copolymerizable monomers is 100 mol% with respect to (meth) acrylamide. Is usually 100 to 45 mol%, preferably 98 to 74 mol%, and the ionic vinyl monomer is usually 0 to 55 mol%, preferably 2 to 26 mol%. The other copolymerizable monomer is used in place of a part of the (meth) acrylamide, and is usually used in an amount of 0 to 20 mol%, preferably 0.01 to 10 mol%.

  In addition, the usage-amount of a cationic vinyl monomer and an anionic vinyl monomer in an ionic vinyl monomer is 0-27.5 mol% normally, respectively.

  In carrying out the polymerization of the monomer, a conventionally known polymerization initiator can be used. Specific examples of the polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, and the like. Peroxides of sodium, bromate such as sodium bromate and potassium bromate, perborates such as sodium perborate and ammonium perborate, percarbonates such as sodium percarbonate, potassium percarbonate and ammonium percarbonate And perphosphates such as sodium perphosphate, potassium perphosphate, and ammonium perphosphate. These polymerization initiators can be used singly or in combination of two or more, and can be used as a redox polymerization initiator in combination with a reducing agent. Examples of the reducing agent include sulfites such as sodium sulfite, bisulfites such as sodium bisulfite, organic amines such as N, N, N ′, N′-tetramethylethylenediamine, and reducing sugars such as aldose. it can. Moreover, these reducing agents may be used individually by 1 type, and may use 2 or more types together. Further, as polymerization initiators other than those described above, azobisisobutyronitrile, 2,2′-azobis-2-amidinopropane hydrochloride, 2,2′-azobis-2,4′-dimethylvaleronitrile, 4,4 An azo polymerization initiator such as' -azobis-4-cyanovaleric acid and salts thereof can also be used.

Moreover, a conventionally well-known chain transfer agent can be used together with a paper strength agent as needed. Conventionally known chain transfer agents include compounds having one or more hydroxyl groups in the molecule, compounds containing one or more mercapto groups in the molecule, and one or more carbon-carbons in the molecule. Examples thereof include compounds having an unsaturated bond, hypophosphorous acid and the like.
Examples of the compound having one or more hydroxyl groups in the molecule include oligomers and polymers such as isopropyl alcohol, butanol, ethylene glycol, glycerin alcohols, polyethylene oxide, polyglycerin, glucose, ascorbic acid, sucrose, etc. Saccharides and vitamins.
Examples of the compound containing one or more mercapto groups in the molecule include butyl mercaptan, mercaptoethanol, thioglycolic acid and its ester, mercaptopropionic acid and its ester, thioglycerin, cysteamine and its salt, etc. Can do.
Examples of the compound having one or more carbon-carbon unsaturated bonds in the molecule include (meth) allyl alcohol and ester derivatives thereof, (meth) allylamine, diallylamine, dimethallylamine and amide derivatives thereof, triallylamine, and trimetallic. Examples include ruamine, (meth) allylsulfonic acid and salts thereof, allyl sulfides, and allyl mercaptans.

  As a paper strength agent that can be used in the present invention, a (meth) acrylamide polymer is synthesized by using a monomer and a solvent (an organic solvent) in a predetermined reaction vessel under an inert gas atmosphere such as nitrogen. And the chain transfer agent as necessary, and under stirring, the polymerization initiator is added to start the polymerization, whereby the paper strength that can be used in the paperboard production method of the present invention A (meth) acrylamide polymer as an agent is obtained.

  The cation-modified (meth) acrylamide polymer by the Hofmann decomposition reaction may be any (meth) acrylamide polymer that has been cation-modified by Hoffman decomposition reaction, and (meth) acrylamide polymer before modification may be (meta) ) Copolymers with nonionic monomers, cationic monomers, and anionic monomers copolymerizable with acrylamide, and those in which a crosslinkable monomer or a chain transfer agent is used in combination.

  Examples of the nonionic monomer copolymerizable with the (meth) acrylamide include acrylonitrile, (meth) acrylic acid ester, vinyl acetate and the like.

  Examples of the cationic monomer copolymerizable with (meth) acrylamide include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, allylamine, diallylamine and the like. Vinyl monomers having amino groups or salts of inorganic or organic acids thereof or tertiary amino group-containing vinyl monomers and methyl chloride, benzyl chloride, dimethyl sulfate, epichlorohydrin, glycidyl trimethyl ammonium chloride, 3-chloro-2 -Vinyl monomers having a quaternary ammonium group obtained by a reaction with a quaternizing agent such as hydroxypropyltrimethylammonium chloride.

  Examples of the anionic monomer copolymerizable with (meth) acrylamide include acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, fumaric acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, (meth) Examples thereof include vinyl monomers such as allylsulfonic acid or sodium, potassium and ammonium salts thereof.

  Examples of the crosslinkable vinyl monomer copolymerizable with (meth) acrylamide include bis (meth) acrylamides such as methylolacrylamide, methylenebis (meth) acrylamide, and ethylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, and diethylene glycol. Di (meth) acrylates such as di (meth) acrylate and polyethylene glycol di (meth) acrylate, divinyl esters such as divinyl adipate and divinyl sebacate, epoxy acrylates, urethane acrylates, divinylbenzene, 1,3,3 5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, triallyl trimellitate, triallylamine, N, N-diallylacrylamide, tetramethylol Tan tetraacrylate, tetraallyl pyromellitate acrylate, N with N-substituted amido group, N- dimethyl acrylamide, N- hydroxyethyl acrylamide.

  The cation-modified (meth) acrylamide polymer by the Hofmann decomposition reaction may be copolymerized with one or a plurality of monomers copolymerizable with the (meth) acrylamide. % Is 60% or more.

  As a method for producing the (meth) acrylamide polymer, various conventionally known methods can be employed. For example, in a reaction vessel equipped with a stirrer and a nitrogen gas introduction tube, the aforementioned monomers and water are charged, and as a polymerization initiator, peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, ammonium hydroperoxide, Or a redox initiator that combines a peroxide and a reducing agent such as bisulfite, or a water-soluble azo polymerization initiator such as 2,2-azobis- (2-amidinopropane) hydrochloride, If necessary, a polymerization regulator or chain transfer agent such as isopropyl alcohol, allyl alcohol, sodium hypophosphite, mercaptoethanol, thioglycolic acid or the like is appropriately used, and the reaction is carried out at a reaction temperature of 20 to 90 ° C. for 1 to 5 hours. The desired (meth) acrylamide polymer can be obtained.

  The cation modification by the Hofmann decomposition reaction of the (meth) acrylamide polymer may be the same as the conventional method. For example, by adding a hypohalite and an alkali catalyst to the aqueous solution of the aforementioned (meth) acrylamide polymer, the (meth) acrylamide polymer and the hypochlorite are reacted in the alkaline region, Thereafter, an acid is added to adjust the pH to 3.5 to 5.5, or a poly (meth) acrylamide is adjusted by Hofmann decomposition reaction in the presence of choline chloride (for example, JP-A-53-109545). ), A method of adjusting by adding a quaternary reaction product of a tertiary amine having a hydroxyl group and benzyl chloride or a derivative thereof in the Hofmann decomposition reaction (for example, Japanese Patent Publication No. 58-8682), as a stabilizer in the Hoffman decomposition reaction In the method of adjusting by adding an organic polyvalent amine (for example, Japanese Examined Patent Publication No. 60-17322), or in the Hofmann decomposition reaction A method of adjusting by adding a specific cationic compounds as stabilizers Te (e.g., JP-B 62-45884 Publication), and the like.

  As starches, raw starch, which is starch itself, cationized starch obtained by performing various modifications using starch as a raw material, oxidized starch, amphoteric starch, etc., and these starches and the above-mentioned chemically modified starches are enzyme-modified. Enzyme-modified starch and the like can be used. Examples of the starch include starches obtained from various plants such as potato, sweet potato, tapioca, wheat, rice, corn, etc., and derivatives thereof include acetylation, phosphate ester of the starch. Examples thereof include modified starch such as modified starch and the like. These can be used in the form of powder or solution.

  Cationized starch means starch having a cationic group introduced by a cation modification reaction, oxidized starch means starch having an anionic group introduced by an oxidation reaction, and amphoteric starch has both a cationic group and an anionic group. It means the introduced starch.

  In introducing a cationic group of starch, for example, starch or a derivative thereof is a known cationizing agent such as 3-chloro-2-hydroxypropyl, trimethylammonium chloride, glycidyltrimethylammonium chloride, dimethylaminoethyl chloride, or the like. It can be obtained by reacting in the presence of

  As the starch having a cationic group, starch having reduced viscosity can also be used. Examples of the viscosity reducing method include an oxidizing agent treatment or a method of performing enzymatic degradation as enzyme modification.

  As the oxidizing agent, conventionally known and commonly used oxidizing agents can be used. Specific examples of the oxidizing agent include hypochlorites such as sodium hypochlorite, potassium hypochlorite, and ammonium hypochlorite, and persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate. , Peroxides such as benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, bromates such as sodium bromate and potassium bromate, sodium perborate, perboric acid Perborate such as ammonium, percarbonate such as sodium percarbonate, potassium percarbonate, ammonium percarbonate, perphosphate such as sodium perphosphate, potassium perphosphate, ammonium perphosphate may be used. it can. The oxidizing agent can be used alone or in combination of two or more.

  Examples of starch degrading enzymes used for enzymatic degradation include α-amylase, β-amylase, γ-amylase, and isoamylase produced by various bacteria, yeasts, animals and plants. Among these, α-amylase is most preferable in that it does not generate excessive low molecular weight substances or monosaccharides.

  The starches after cooking preferably have a viscosity of a 1% solid content aqueous solution at 25 ° C. of 5 to 10,000 mPa · s, more preferably 5 to 1,000 mPa · s.

<Pitch control agent>
In the paperboard manufacturing method of the present invention, it is preferable to add a pitch control agent to the pulp slurry. Examples of pitch control agents include organic pitch control agents and inorganic pitch control agents.

  The organic pitch control agent is a cationic polymer such as a cationic polymer obtained by polymerization containing at least one cationic monomer, an amine-epihalohydrin resin, a polyethyleneimine, a polyethyleneimine modified product, a polyvinylamine, or the like. Examples thereof include compounds, nonionic dispersants, and anionic surfactants.

  Examples of the cationic monomer used in the cationic polymer include compounds represented by the following formulas (4) to (6), diallylamines, and the like. These may be used alone, but may be used in combination of two or more. it can.

(In the formula (4), A is oxygen or NH, n is an integer of 2 to 4, R ¹² is H or a methyl group, R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ are the same or different carbons. The lower alkyl group of 1 to 3 and X ⁻ and Y ⁻ represent the same or different anionic groups.)

  Specific cationic monomers of the formula (4) include 2-hydroxy-N, N, N, N ′, N′-pentamethyl-N ′-(3- (meth) acryloylaminopropyl) -1,3. -Propanediammonium dichloride, 2-hydroxy-N-benzyl-N, N-diethyl-N ', N'-dimethyl-N'-(2- (meth) acryloyloxyethyl) -1,3-propanediammonium di- Examples include bromide.

（但し、式（５）中、Ａは酸素又はＮＨ、ｎは２〜４の整数、Ｒ¹⁸はＨ又はメチル基、Ｒ¹⁹、Ｒ²⁰は同一又は異なる炭素数１〜３の低級アルキル基を示す。）

(In the formula (5), A represents oxygen or NH, n represents an integer of 2 to 4, R ¹⁸ represents H or a methyl group, R ¹⁹ and R ²⁰ represent the same or different lower alkyl groups having 1 to 3 carbon atoms. Show.)

  Specific cationic monomers of the above formula (5) include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and the like.

（但し、式（６）中、Ａは酸素又はＮＨ、ｎは２〜４の整数、Ｒ²¹はＨ又はメチル基、Ｒ²²、Ｒ²³は同一又は異なる炭素数１〜３の低級アルキル基、Ｒ²⁴は低級アルキル基又はベンジル基、Ｚ⁻はアニオン性基を示す。）

(In the formula (6), A is oxygen or NH, n is an integer of 2 to 4, R ²¹ is H or a methyl group, R ²² and R ²³ are the same or different lower alkyl groups having 1 to 3 carbon atoms, R ²⁴ represents a lower alkyl group or a benzyl group, and Z ⁻ represents an anionic group.)

  As a specific cationic monomer of the above formula (6), the cationic monomer represented by the above formula (6) is converted to an appropriate quaternizing agent such as alkyl halide, dialkyl carbonate, alkyl tosylate, alkyl mesylate, dialkyl. It is obtained by quaternization with sulfuric acid, benzyl halide, etc., for example, N-ethyl-N, N-dimethyl- (2- (meth) acryloyloxyethyl) ammonium bromide, N-benzyl-N, N-dimethyl- ( 3- (meth) acryloylaminopropyl) ammonium chloride and the like.

  Examples of diallylamines include diallylamine, diallylmethylamine, and diallyldimethylammonium chloride.

  The cationic polymer preferably contains 10 mol% or more of a cationic monomer, and other copolymerizable monomers include acrylonitrile, (meth) acrylamide, (meth) acrylic acid methyl ester, and (meth) acrylic acid. Nonionic monomers such as ethyl esters, α, β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, α, β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, and styrene sulfonic acid , Unsaturated sulfonic acids such as vinyl sulfonic acid, and salts thereof, for example, anionic monomers such as sodium salt, potassium salt, ammonium salt, etc., and conventionally known chain transfer agents and crosslinking agents are used. May be.

  There is no restriction | limiting in particular as a polymerization method of the said cationic polymer, A conventionally well-known method is employable.

  Furthermore, as described above, the cationic monomer of formula (5) is not only subjected to the polymerization reaction after quaternization with the quaternizing agent, but also the cationic monomer belonging to the above formula (5), etc. Can be quaternized with the above quaternizing agent during or after the polymerization reaction. In this case, all may be quaternized, but some may be quaternized.

  The amine-epihalohydrin resin can be obtained by reacting amines with epihalohydrin. The amine that can be used as the amine is not particularly limited as long as it is an amine having an amino group capable of reacting with at least one epihalohydrin in the molecule, but is not limited to primary amine, secondary amine, tertiary amine. One or more amines selected from the group consisting of amines, alkylene diamines, polyalkylene polyamines, and alkanol amines are preferred.

  Examples of the amine include methylamine, ethylamine, propylamine, isopropylamine, allylamine, n-butylamine, sec-butylamine, tert-butylamine, cyclohexylamine, cyclooctylamine, dimethylamine, diethylamine, dipropylamine, methylethylamine, Methylpropylamine, trimethylamine, triethylamine, tripropylamine, triisopropylamine, ethylenediamine, trimethylenediamine, and propylenediamine, N, N dimethylaminopropylamine, 1,3-diaminocyclohexyl, 1,4-diaminocyclohexyl, diethylenetriamine, Triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, monoethanolamine Diethanolamine, N- methylethanolamine, triethanolamine, N, N- diethylethanolamine, N, N- dimethylethanolamine and the like.

  As epihalohydrin, epichlorohydrin, epibromohydrin and the like can be used, and these can be used alone or in admixture of two or more. Epichlorohydrin is preferable as the epihalohydrin.

  There is no restriction | limiting in particular as a polymerization method of the said amine-epihalohydrin resin, A conventionally well-known method is employable.

  Examples of the inorganic pitch control agent include aluminum sulfate (sulfuric acid band), polyaluminum chloride, polyaluminum silicate sulfate, polyaluminum compound such as polyaluminum hydroxide, polyiron sulfate, zirconium carbonate, bentonite, talc (fine powder), etc. Is mentioned.

<Yield agent>
In the paperboard manufacturing method of the present invention, it is preferable to add a retention agent to the pulp slurry. Examples of the retention agent include an organic retention agent and an inorganic retention agent.

  Examples of the organic retention agent include acrylamide polymers, starches, polyvinyl alcohols, and celluloses. Some of these also function as a paper strength agent, but those for the purpose of improving the yield have a larger molecular weight and higher aggregability than the paper strength agent. The ionicity of the retention agent may be any of cationic, anionic, amphoteric, and nonionic, and two or more kinds can be appropriately combined. Moreover, the structure of the polymer constituting the organic retention agent may have any of a linear structure, a branched structure, and a crosslinked structure.

  Examples of inorganic retention agents include bentonite, colloidal silicic acid, and aluminum compounds.

  In the paperboard manufacturing method of the present invention, an aluminum compound is added to the pulp slurry as necessary. Examples of the aluminum compound include water-soluble aluminum compounds such as aluminum sulfate (sulfuric acid band), polyaluminum chloride, alumina sol, polysulfuric acid aluminum silicate, aluminum silicate sol, and polyaluminum hydroxide. Bands and polyaluminum chloride are preferred. These aluminum compounds can be used alone or in combination of two or more. It is preferable not to use an aluminum compound, and when it is used, it is preferable to use the aluminum compound in an amount of 1% by mass or less, and 0.1 to 0.5% by mass based on the solid content of the pulp slurry. More preferred.

<Location and amount of sizing composition added>
In the method for producing paperboard of the present invention, the location where the sizing composition is added is not particularly limited, but it is preferably added between the beating machine outlet and the inlet inlet of the papermaking process. Moreover, it can also be divided and added not only to one place but to several places. Furthermore, you may mix with the other chemical | medical agent used at a papermaking process, and may add to a pulp slurry.

  The addition rate per pulp solid content of the sizing agent composition is an active ingredient, preferably 0.03 to 1% by mass, more preferably 0.05 to 0.3% by mass. When the amount is less than the above range, the size effect may be insufficient, and when used beyond the above range, the effect may reach a peak.

<Location and amount of paper strength agent added>
When the paper strength agent is added to the pulp slurry in the paperboard production method of the present invention, the addition location is not particularly limited, but it is preferably added between the beating machine outlet and the inlet inlet in the papermaking process. Moreover, it can also be divided and added to not only one place but several places.

  The addition ratio of the paper strength agent per pulp solid content is preferably 0.02 to 3% by mass, more preferably 0.05 to 1% by mass. If it is less than 0.02% by mass, the paper strength effect may be insufficient, and even if it exceeds 3% by mass, the effect may reach its peak.

<Location and amount of yield agent added>
When the yield agent is added to the pulp slurry in the paperboard manufacturing method of the present invention, the addition location is not particularly limited, but it is preferably added at a location with good mixing between the beating machine outlet and the inlet outlet in the papermaking process. . Moreover, it is sufficient to divide and add not only to one place but to multiple places, and 1 type, or 2 or more types of retention agents may be used.

  The addition rate of the retention agent per pulp solid content is preferably 0.005 to 2% by mass, more preferably 0.01 to 1% by mass.

<Pitch control agent addition location and amount>
When the pitch control agent is added to the pulp slurry in the paperboard manufacturing method of the present invention, the addition location is not particularly limited, but it is added at a location with good mixing between the beating machine outlet and the inlet outlet in the papermaking process. preferable. Moreover, it is sufficient to divide and add not only to one place but to several places, and 1 type, or 2 or more types of pitch control agents may be used.

  When adding the said pitch control agent to a pulp slurry, the addition rate per pulp solid content becomes like this. Preferably it is 0.005-1 mass%, More preferably, it is 0.01-0.5 mass%. If the addition rate is less than 0.005% by mass, the antifouling effect may be poor, and if the addition rate exceeds 1% by mass, fixing of paper strength agents and the like may be reduced.

  In addition to the above additives, the pulp slurry contains wet paper strength agents such as polyamide polyamine epichlorohydrin resin, and fillers such as calcium carbonate such as light calcium carbonate and heavy calcium carbonate, clay, and titanium oxide. There is no problem in using them together as appropriate.

  A paperboard base paper can be produced by dehydrating and drying a slurry in which a pulp slurry and a chemical such as a paper strength agent and a sizing agent are mixed by a conventional method.

  After producing the paperboard base as described above, the coating liquid can be applied to the surface of the paperboard base as necessary.

  For coating liquid, surface paper strength agent, surface sizing agent, anti-slip agent, antiseptic, antifoaming agent, viscosity modifier, rust inhibitor, mold release agent, flame retardant, dye, water repellent, ruler However, it is preferable that the coating liquid contains a surface paper strength agent and / or a surface sizing agent.

About the coating amount of a surface paper strength agent, it is 0.05-5 g / m < ² > normally by solid content, Preferably it is 0.1-2 g / m < ² >. Moreover, about the coating amount of a surface sizing agent, it is 0.01-1 g / m < ² > normally by solid content, Preferably it is 0.02-0.1 g / m < ² >.
The density | concentration of the surface sizing agent contained in a coating liquid is 0.1-5 mass% normally, Preferably it is 0.2-1 mass%.
Further, coating amount of the coating solution containing the surface sizing agent, 0.01 to 1 g / ^{m 2} in solids, preferably 0.02~0.1g / ^{m 2.} Within the above range, the size effect is particularly good.

  The coating liquid can be applied to paper by a known method, for example, size press, film press, gate roll coater, rod metalling coater, blade coater, calendarer, bar coater, knife coater, air knife coater. It is possible to apply using. Moreover, spray coating can also be performed.

<Surface paper strength agent>
Examples of the surface paper strengthening agent include synthetic polymers such as acrylamide resins and polyvinyl alcohols, and natural polymers of polysaccharides such as starches, celluloses, chitosan, alginic acid, and carrageenan. Among these, acrylamide resins are preferably used.

  Acrylamide resins may be anionic, cationic or nonionic, and at least acrylamides and, if necessary, ionic vinyl monomers, nonionic vinyl monomers and crosslinking agents, etc. Can be obtained by copolymerization with a copolymerizable monomer.

  As the acrylamides, acrylamide and methacrylamide are preferable, and N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N- Any one or more of N-substituted (meth) acrylamides such as t-octyl (meth) acrylamide can be used in combination with acrylamide and methacrylamide.

  Examples of the ionic vinyl monomer include an anionic vinyl monomer and a cationic vinyl monomer.

  Examples of the anionic vinyl monomer include α, β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, and salts such as alkali metal salts and ammonium salts such as sodium salts and potassium salts, maleic acid, and fumaric acid. Α, β-unsaturated dicarboxylic acids such as acid, itaconic acid, citraconic acid and the like, salts such as alkali metal salts and ammonium salts such as sodium salt and potassium salt, aconitic acid, 3-butene-1,2,3- Α, β-unsaturated tricarboxylic acids such as tricarboxylic acid and 4-pentene-1,2,4-tricarboxylic acid, and salts such as alkali metal salts and ammonium salts such as sodium salt and potassium salt thereof, (meth) allylsulfone Organic sulfone such as acid, vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid Acids and salts thereof such as alkali metal salts and ammonium salts such as sodium and potassium salts, phosphonic acids such as vinylphosphonic acid and α-phenylvinylphosphonic acid, and alkali metal salts and ammonium salts such as sodium and potassium salts thereof Etc., and one or more of these can be used.

  Examples of the cationic vinyl monomer include a vinyl monomer having a primary amino group, a vinyl monomer having a secondary amino group, a vinyl monomer having a tertiary amino group, and a vinyl monomer having a quaternary ammonium salt.

  Examples of the vinyl monomer having a primary amino group include allylamine, methallylamine, and salts thereof. These salts include inorganic acid salts such as hydrochloride and sulfate, and organic acid salts such as formate and acetate.

  Examples of the vinyl monomer having a secondary amino group include diallylamine, dimethallylamine, and salts thereof. These salts include inorganic acid salts such as hydrochloride and sulfate, and organic acid salts such as formate and acetate.

  Further, as the vinyl monomer having a secondary amino group, vinyl monomers having the primary amino group such as allylamine and methallylamine, and alkyl halides such as methyl chloride and methyl bromide, benzyl chloride, and benzyl bromide are used. Examples thereof include monomers converted into secondary amine acid salts by reaction with aralkyl halides, dimethyl sulfate, dialkyl sulfates such as diethyl sulfate, epichlorohydrin and the like.

  Examples of the vinyl monomer having a tertiary amino group include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, diethylaminopropyl acrylate, and diethylaminopropyl methacrylate. And dialkylaminoalkyl (meth) acrylamides such as dialkylaminoalkyl (meth) acrylates, dimethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide, diethylaminopropyl acrylamide, and diethylaminopropyl methacrylamide, and salts thereof. it can. These salts include inorganic acid salts such as hydrochloride and sulfate, and organic acid salts such as formate and acetate.

  Further, as the vinyl monomer having a tertiary amino group, vinyl monomers having the secondary amino group such as diallylamine and dimethallylamine, and alkyl halides such as methyl chloride and methyl bromide, aralkyl such as benzyl chloride and benzyl bromide. Examples thereof include monomers converted into acid salts of tertiary amines by reaction with any one of halides, alkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epichlorohydrin.

  Examples of the vinyl monomer having a quaternary ammonium salt include diallyldimethylammonium chloride, dimethallyldimethylammonium chloride, diallyldiethylammonium chloride, and diethyldimethallylammonium chloride.

  Examples of the vinyl monomer having a quaternary ammonium salt include a vinyl monomer obtained by reacting the vinyl monomer having a tertiary amino group with a quaternizing agent. Examples of the quaternizing agent include alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, alkyl sulfates such as dimethyl sulfate and diethyl sulfate, epichlorohydrin, 3-chloro- Examples include 2-hydroxypropyltrimethylammonium chloride and glycidyltrialkylammonium chloride.

  Specific examples of vinyl monomers having the quaternary ammonium salts include acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyldimethylbenzylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride, and acryloyloxypropyldimethyl. Examples include benzylammonium chloride and methacryloyloxypropyldimethylbenzylammonium chloride.

  Examples of the nonionic vinyl monomer include esters of alcohol and (meth) acrylic acid, styrene, styrene derivatives, (meth) acrylonitrile, vinyl acetate, vinyl propionate, methyl vinyl ether, and the like, one or two of these. It can be used above.

  Examples of the crosslinking agent include di (meth) acrylates such as ethylene glycol di (meth) acrylate and diethylene glycol di (meth) acrylate, and bis (meta) such as methylene bis (meth) acrylamide and N, N-bisacrylamide acetic acid. ) Bifunctional vinyl monomers such as acrylamides, divinyl adipate, diallyl malate, N-methylolacrylamide, diallyldimethylammonium, glycidyl (meth) acrylate, 1,3,5-triacryloylhexahydro-S-triazine, Trifunctional amine monomers such as triallylamine, triallyl isocyanurate, triallyl trimellitate, tetramethylolmethane tetraacrylate, tetraallyl pyromellilate, tetraallylamine salt, tetraallyloxy Tetrafunctional vinyl monomers such as ethane.

  In addition, water-soluble aziridinyl compounds such as tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, (poly) ethylene glycol diglycidyl ether, (poly) Water-soluble polyfunctional epoxy compounds such as glycerin diglycidyl ether, 3- (meth) acryloxymethyltrimethoxysilane, 2- (meth) acrylamide-2-methylpropyltrimethoxysilane, vinyldimethylmethoxysilane, vinyltrichlorosilane, Examples thereof include silicon compounds such as vinyltriphenoxysilane and 2- (meth) acrylamide-2-methylpropyltriacetoxysilane, and these can be used alone or in combination.

  In order to obtain the acrylamide resins, ureas and ammonium salts can be added before and after the monomers are polymerized, and it is particularly preferable to add ureas before the reaction. Examples of ureas include urea, thiourea, ethylene urea, and ethylene thiourea. Examples of ammonium salts include ammonium sulfate and ammonium phosphate. These can be used alone or in combination. . Among these, it is particularly preferable economically to use urea or ammonium sulfate. The amount of urea used is preferably 5 to 30% by mass with respect to the total amount of monomers such as acrylamides.

  The mass ratio of the acrylamide component and the ionic monomer component used in the acrylamide resin is acrylamide component / ionic monomer component = 100 to 50/0 to 50, preferably 98 to 80/2 to 20.

  The reaction for obtaining acrylamide resins is charged in a predetermined reaction vessel so that the total concentration of monomers that are constituents of acrylamide resins is 5 to 50% by mass, preferably 10 to 40% by mass. The polymerization initiator is used and the reaction temperature is 40 to 100 ° C. and the reaction is performed for 1 to 10 hours. Of course, according to the characteristics of the monomer component used, the reaction can be carried out by continuously dropping the monomer or adding the monomer in portions.

  The polymerization initiator used for the reaction of acrylamide-based resins is not particularly limited, and known and conventional ones are used. Examples of radical polymerization initiators include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, and di-tert-butyl peroxide, and bromic acid. Bromate such as sodium and potassium bromate, perborate such as sodium perborate, potassium perborate and ammonium perborate, percarbonate such as sodium percarbonate, potassium percarbonate and ammonium percarbonate, percarbonate Examples thereof include perphosphates such as sodium phosphate, potassium perphosphate, and ammonium perphosphate.

  These polymerization initiators can be used alone, but can also be used as a redox polymerization initiator in combination with a reducing agent. Examples of the reducing agent include sulfites, bisulfites, organic amines such as N, N, N ′, N′-tetramethylethylenediamine, 2,2′-azobis-2-amidinopropane hydrochloride, azobisisobutyronitrile. 2,2′-azobis-2,4-dimethylvaleronitrile, azo compounds such as 4,4′-azobis-4-cyanovaleric acid, and reducing sugars such as aldose. Two or more of these polymerization initiators may be used in combination. The usage-amount of a polymerization initiator is 0.01-5 mass% normally with respect to the total amount of the monomer used for acrylamide resin.

  Acrylamide resins are aqueous solutions having a solid concentration of 5 to 50% by mass, preferably 10 to 40% by mass, and a viscosity at 25 ° C. (Brookfield rotational viscometer) of 500 to 15,000 mPa · s, preferably 1,000 to 10,000 mPa · s. If it exceeds 15,000 mPa · s, the coating workability may deteriorate, and if it is less than 500 mPa · s, the effect of improving the specific burst strength and surface strength may be inferior.

The pH of acrylamide resins can be adjusted as appropriate using an acid or alkali after the reaction is completed. Examples of acids and alkalis include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, organic acids such as formic acid, acetic acid and propionic acid, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, sodium carbonate and potassium carbonate Alkali metal carbonates such as ammonia, amine bases such as ammonia, methylamine and dimethylamine can be used.

  Examples of the polyvinyl alcohols include cationic polyvinyl alcohol, anionic polyvinyl alcohol, amphoteric polyvinyl alcohol, and nonionic polyvinyl alcohol.

  Examples of the cationic polyvinyl alcohol include polyvinyl alcohol having a tertiary amino group and polyvinyl alcohol having a quaternary ammonium salt. Examples of the anionic polyvinyl alcohol include polyvinyl alcohol having a carboxyl group. The amphoteric polyvinyl alcohol refers to polyvinyl alcohol having a cationic group such as a tertiary amino group and an anionic group simultaneously.

  The polyvinyl alcohols are produced by various methods, and are usually produced by hydrolysis or alcoholysis (alcoholization) of a polyvinyl ester. The polyvinyl ester includes a homopolymer of vinyl ester, a copolymer of two or more vinyl esters, a copolymer of vinyl ester and other ethylenically unsaturated monomers, and the like. Here, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl pivalate and the like can be used as the vinyl ester. Among these, industrially manufactured and inexpensive vinyl acetate can be preferably used. There are various other ethylenically unsaturated monomers copolymerizable with the vinyl ester, and there is no particular limitation. For example, α-olefin, halogen-containing monomer, carboxylic acid-containing monomer, (Meth) acrylic acid ester, vinyl ether, sulfonic acid-containing monomer, amide group-containing monomer, amino group-containing monomer, quaternary ammonium salt-containing monomer, silyl group-containing monomer, hydroxyl group-containing monomer Examples thereof include monomers and acetyl group-containing monomers.

  The polyvinyl alcohols are not particularly limited as to the degree of polymerization, but usually the degree of polymerization is preferably 300 to 4000. The saponification degree of polyvinyl alcohols is not particularly limited, but is usually 60 to 100 mol%, preferably 80 to 100 mol%, and more preferably 95 to 100 mol%.

  Examples of the starches include raw starch that is starch itself, chemically modified starch such as oxidized starch, cationized starch, and amphoteric starch obtained by performing various modifications using starch as a raw material, and these starches and the chemically modified starch are enzymatically modified. Enzyme-modified starch and the like can be used. Examples of the starch include starch obtained from various plants such as potato, sweet potato, tapioca, wheat, rice, corn, etc., and derivatives thereof include acetylation, phosphate esterification and the like of the starch. Examples thereof include modified or treated starch. These can be used in the form of powder or solution.

  Cationized starch means starch having a cationic group introduced by a cation modification reaction, oxidized starch means starch having an anionic group introduced by an oxidation reaction, and amphoteric starch has both a cationic group and an anionic group. It means the introduced starch.

  As the oxidizing agent for starches, a conventionally known and commonly used oxidizing agent can be used. Specific examples of the oxidizing agent include hypochlorites such as sodium hypochlorite, potassium hypochlorite, and ammonium hypochlorite, and persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate. , Peroxides such as benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, bromates such as sodium bromate and potassium bromate, sodium perborate, perboric acid Perborate such as ammonium, percarbonate such as sodium percarbonate, potassium percarbonate, ammonium percarbonate, perphosphate such as sodium perphosphate, potassium perphosphate, ammonium perphosphate may be used. it can. These oxidizing agents can be used alone or in combination of two or more.

  In introducing a cationic group into starch, for example, starch or a derivative thereof is a known cationizing agent such as 3-chloro-2-hydroxypropyl, trimethylammonium chloride, glycidyltrimethylammonium chloride or dimethylaminoethyl chloride. It is obtained by reacting in the presence of a catalyst.

  Examples of starch degrading enzymes used for enzymatic degradation include α-amylase, β-amylase, γ-amylase, and isoamylase produced by various bacteria, yeasts, animals and plants. Among these, α-amylase is most preferable in that it does not generate excessive low molecular weight substances or monosaccharides.

  The aqueous solution viscosity of the starch after cooking is not particularly limited. Usually, the viscosity of an aqueous solution having a solid content of 10% at 25 ° C. is 1 to 1000 mPa · s, preferably 5 to 500 mPa in a Brookfield viscometer. · S, more preferably 10 to 100 mPa · s.

  Examples thereof include carboxymethyl cellulose such as cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose. These can be used in the form of powder or solution.

In addition, it is preferable that the coating liquid density | concentration at the time of coating a surface paper strength agent as a coating liquid is 0.1-15 mass%. Coating weight sizing degree of the base paper, it can appropriately be set considering the other, 0.05-5 g / ^{m 2} typically with solids, preferably 0.1-2 g / ^{m 2.}

<Surface sizing agent>
As the surface sizing agent, known anionic surface sizing agents or cationic surface sizing agents can be used.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded.

(Examples 1-9, Comparative Examples 1-10)
Preparation of water dispersible sizing agent An alkenyl succinic anhydride (AS1533, manufactured by Seiko PMC Co., Ltd., 15 parts by mass) and each of the substances shown in Tables 1 to 3 were mixed in the proportions shown in Tables 1 to 3. And an aqueous polymer dispersant (SP1808, manufactured by Seiko PMC Co., Ltd., 18.3 parts by mass) are mixed using a universal homogenizer (manufactured by Nippon Shiki Seisakusho Co., Ltd.) at 10,000 rpm for 60 seconds, and water is added. An aqueous dispersible sizing agent having 1% by mass of alkenyl succinic anhydride and a particle size of 0.8 μm was obtained. In addition, the fatty acid ester in the Examples described in Tables 1 to 3 has a viscosity at 1 atm and 20 ° C. of 100 mPa · S or less.

Dirt evaluation (adhesiveness)
The ASA hydrolyzate and each substance shown in Tables 1 to 3 were mixed to prepare a sample. About each sample, the tensile stress in 30 degreeC was measured using the tacking tester (The apparatus which contacts a measurement sample and measures the load at the time of pulling apart). The larger the value of tensile stress, the higher the tackiness of the sample, and the easier it is to adhere as dirt in the papermaking system. Note that ASA hydrolyzate is produced from ASA in the papermaking system, and is extremely sticky than ASA, and easily becomes soiled in the papermaking process. For this tackiness evaluation, ASA hydrolyzate is used instead of ASA. It was.

Dirt evaluation (hydrolysis rate of water-dispersible sizing agent)
The water-dispersible sizing agent was diluted to a concentration of 0.02% by mass with diluted water having a hardness of 300 ppm (calcium carbonate), and an aqueous sodium hydroxide solution was added dropwise for 45 minutes with stirring so as to be constant at 40 ° C. and pH 8. From the amount of sodium hydroxide added dropwise, the hydrolysis rate of the water dispersible sizing agent was calculated. A higher hydrolysis rate indicates a faster hydrolysis rate. The faster the hydrolysis rate, the faster the ASA hydrolyzate is produced, which indicates that contamination is likely to occur. In most cases, contamination occurs when the hydrolysis rate is 70% or more.

Dirt evaluation (stability of fatty acid ester)
A slurry of the water dispersible sizing agent (concentration 0.1% by mass) and light calcium carbonate (Tama Pearl 121, manufactured by Okutama Kogyo Co., Ltd., concentration 1% by mass) prepared as described above was prepared, and the slurry was prepared at 40 ° C. for 48 hours. After stirring, decomposition of the fatty acid ester was confirmed by ¹ H-NMR. Dirt is easily generated when the fatty acid ester is decomposed.

  It can be seen from Table 1 that by mixing a specific fatty acid ester with ASA, it is possible to reduce the tackiness of the ASA hydrolyzate and to reduce the hydrolysis rate of ASA. However, although fatty acid polyvalent esters that can be non-cellulose reactive sizing agents other than specific fatty acid esters can reduce the tackiness, ASA is rapidly hydrolyzed, like glycerin and palmitic acid esters or stearic acid esters. In the case of a polyvalent fatty acid ester, the effect of reducing the tackiness was not observed. Moreover, since polyhydric fatty acid ester was solid, it could not be emulsified. Furthermore, as a lipophilic substance that can be a non-cellulose-reactive sizing agent other than the specific fatty acid ester, paraffin oil and soybean oil were examined, and the tackiness reducing effect of the ASA hydrolyzate was not observed. In addition, the effect of slowing the hydrolysis rate of ASA was not observed. Further, when palm oil that can be used as a raw material for fatty acid esters was examined, the effect of reducing the hydrolysis rate of ASA was not seen at all, although the effect of reducing the tackiness of the ASA hydrolyzate was observed.

  From Table 2, when the proportion of the specific fatty acid ester is as small as 5% by mass, the effect of reducing tackiness is small, and the hydrolysis rate of the ASA emulsion is fast (exceeds 70% by mass). On the other hand, when the proportion of the ester is large, there is no difference in the effect between 50% by mass and 60% by mass. Therefore, the effect of mixing the specific fatty acid ester with ASA reaches a peak at 50% by mass, and the specific fatty acid. Since the reduction of the size effect by increasing the proportion of the ester may be a problem, the mixing amount of the specific fatty acid ester is preferably 10 to 50% by mass.

  It can be seen from Table 3 that specific fatty acid esters having a small number of carbon atoms in the alcohol portion of esters such as specific fatty acid methyl and ethyl decompose in 48 hours. When the specific fatty acid ester is decomposed, the above-described antifouling effect is lowered. Therefore, when there is a long-term retention of the sizing composition exceeding 48 hours, the alcohol part of the fatty acid ester has 4 or more carbon atoms. It is desirable that

(Examples 11-25, Comparative Examples 11-20)
Preparation of water-dispersible sizing agent Implemented except that each substance described in Tables 1 to 3 and each substance described in Tables 4 to 6 were used in the ratios described in Tables 4 to 6 instead of their use ratios A water dispersible sizing agent was prepared in the same manner as in Example 1. In addition, the fatty acid ester in the Examples described in Tables 4 to 6 has a viscosity at 1 atm and 20 ° C. of 100 mPa · S or less.

Dirt evaluation (dirt adhesion to metal plate)
Canadian standard freeness 315, corrugated used paper pulp adjusted to 15% ash, 0.2% by weight of water dispersible sizing agent prepared as described above as an active ingredient, and a pitch control agent (AC7314) based on pulp solids (Manufactured by Seiko PMC Co., Ltd.) with respect to the solid content of the pulp so that the solid content is 0.05% by mass, diluted to 0.8% by mass with water having an electric conductivity of 100 mS / m, and then polymer A yield agent (NR12MLS, manufactured by Hymo Co., Ltd.) was added to the pulp solid content so that the solid content was 0.02% by mass. The pH of this pulp slurry was 7.2. Moreover, when the alkalinity of the pulp slurry was measured as described above, it was 108 ppm. After stirring this pulp slurry at 45 ° C. for 60 minutes, according to a conventional method, hand-pulling is performed with a square sheet machine to a basis weight of 100 g / m ² , a metal sheet is placed on the wet paper, and 4.2 kgf for 2 minutes. A flat press was performed. The metal plate was peeled off from the wet paper, and the amount of dirt adhered to the metal plate was visually evaluated in five stages (1 is the case where the dirt is the least, the evaluation value is increased as the dirt increases, and the dirt is the most. Case was 5). The greater the amount of dirt attached to the metal plate, the easier it is for dirt to adhere in the papermaking system.

Size evaluation Canadian standard freeness 311, corrugated used paper pulp adjusted to 15% ash content, 0.2% by mass of water dispersible sizing agent prepared as described above with respect to pulp solid content, pitch control agent (AC7314, manufactured by Seiko PMC Co., Ltd.) When the combined chemicals are evaluated so that the solid content is 0.05% by mass with respect to the solid content of the pulp, the combined chemicals listed in Table 3 are sequentially added to the pulp solid content. After being added to the usage ratio in Table 6 and diluted to 0.8% by mass with water having an electric conductivity of 100 mS / m, a polymer yield agent (NR12MLS, manufactured by Hymo Co.) was added to the pulp solids. It added so that it might become 0.02 mass% as solid content with respect to min. The pH of this pulp slurry was 7.2. Moreover, when the alkalinity of the pulp slurry was measured as described above, it was 110 ppm. The pulp slurry was stirred at 45 ° C. for 60 minutes, then hand-pulled with a noble and wood sheet machine to a basis weight of 80 g / m ² and dried under conditions of a drum dryer at 100 ° C. for 80 seconds. The obtained paper was conditioned for 24 hours in a constant temperature and humidity chamber at 23 ° C. and 50% RH, and then the Cobb sizing degree for 120 seconds was measured according to JIS P 8140.

Explanation of abbreviations in Table 6 AC7314: Organic cationic pitch control agent DS4416 manufactured by Seiko PMC Co., Ltd. Amphoteric acrylamide paper strengthening agent DH4162 manufactured by Seiko PMC Co., Ltd. Hoffman modified acrylamide paper strengthening agent Cato304 manufactured by Seiko PMC Co., Ltd. Cationic starch made from NSC Japan Co., Ltd. and used in paste form Cato 3210: Made from Nippon NSC Co., Ltd. Amphoteric starch cooked in paste form

It can be seen from Table 4 that the fatty acid ester having a specific structure is mixed with ASA, and this mixture is added to a specific pulp slurry, whereby the amount of dirt attached can be reduced (Examples 11 to 16). ).
However, it can be seen that in the case of the fatty acid ester comprising a polyhydric alcohol having no specific structure of the present invention, there is almost no effect of reducing dirt (Comparative Examples 11-14). Moreover, when paraffin oil, soybean oil, and palm oil were examined as lipophilic substances other than fatty acid esters, it was found that there was no soil reduction effect (Comparative Examples 15 to 17).

  From Table 4, in the size evaluation, a fatty acid ester having a specific structure is mixed with ASA, and this mixture is added to a specific pulp slurry, so that a substituted succinic anhydride of 45 ° C. and 60 minutes in a papermaking system is hydrolyzed. It can be seen that even when sufficient time has elapsed for the size effect to decrease due to the decomposition, the excellent size effect is exhibited (Examples 11 to 16). However, in the case of the fatty acid ester which consists of polyhydric alcohol which does not have the specific structure of this invention, it turns out that a size effect is low (Comparative Examples 11-14).

  It can be seen from Table 5 that the proportion of the fatty acid ester having a specific structure of the present invention mixed with ASA is preferably 10 to 50% (Examples 11 and 17 to 19). If it is less than 10%, the effect of preventing stains is small, and if it exceeds 50%, the size effect is remarkably reduced (Comparative Examples 18 to 20).

  From Table 6, as the chemicals used in papermaking, organic cationic pitch control agent (AC7314), Hoffman modified acrylamide paper strength agent (DH4162), and sulfuric acid band have excellent antifouling effect, and organic cationic pitch control. It can be seen that the agent (AC7314), the Hoffman-modified acrylamide-based paper strength agent (DH4162), the cationized starch (Cato304), and the amphoteric starch (Cato3210) are excellent in the size improvement effect (Examples 11, 20 to 25). In particular, it can be seen that the organic cationic pitch control agent (AC7314) and the Hoffman-modified acrylamide paper strength agent (DH4162) are excellent in both the antifouling effect and the size improvement effect (Example 20). 22).

Claims (7)

(A) It is liquid under the conditions of 1 atm and 20 ° C., and a mixture of a fatty acid ester represented by the structural formula of the following formula (1) and (B) a substituted succinic anhydride is used as an emulsion, and
The sizing composition, wherein the mass ratio [(A) :( B)] of the (A) fatty acid ester and the (B) substituted succinic anhydride is 50:50 to 10:90.
R ¹ —COO—R ² Formula (1)
(However, R ¹ in the formula represents an alkyl group or alkenyl group having 5 to 30 carbon atoms, R ^{2 in} the formula represents an alkyl group having 1 to 30 carbon atoms, and R ¹ and R ² are the same. Or different.) The sizing composition according to claim 1, wherein (A) the fatty acid ester has 4 to 30 carbon atoms of R ² in the formula (1).   A papermaking method for reducing stains in a papermaking system using the sizing composition according to claim 1. (1) pH is 6.5 to 8.5,
(2) Alkalinity is 50 to 400 ppm, and (3) Conductivity is 50 to 250 mS / m.
To the pulp slurry,
(4) A method for producing paperboard, wherein papermaking is performed by adding the sizing composition according to claim 1. (A) fatty acid ester, a manufacturing method of paperboard according to claim 4 carbon atoms of ^{R 2} is from 4 to 30 in the formula (1). A board control method according to claim 4 or 5, wherein a pitch control agent is added to the pulp slurry according to claim 4. The method for producing a paperboard according to any one of claims 4 to 6, wherein a polyacrylamide polymer and / or starch is added to the pulp slurry according to claim 4 as a paper strength agent.