JP2017179661A - Emulsion type sizing agent for paper making, manufacturing method of paper and paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an emulsion type sizing agent using an alkylene ketene dimer, excellent in storage stability and mechanical stability and good in size property.SOLUTION: There is provided an emulsion type sizing agent for making paper containing (A) an anionic group-containing polyacrylamide which is a reaction product of monomers (α) consisting of an anionic vinyl monomer (a1) containing a sulfo group-containing unsaturated monomer (a1-1) of more than 95 mass%, a hydrophobic vinyl monomer (a2) having a C4 to 12 hydrocarbon group as a substituent and (meth)acryl amide (a3), (B) a ketene dimer composition which is a mixture of an alkyl ketene dimer having 2 C14 to 16 alkyl groups and a ketene dimer different from the ketene dimer and (C) a water-soluble aluminum compound.SELECTED DRAWING: None

Description

  The present invention relates to an emulsion type sizing agent for papermaking using an alkyl ketene dimer.

  Conventionally, alkenyl succinic anhydride (ASA) and alkyl ketene dimer (AKD), which are so-called reactive sizing agents, are used for neutral papermaking. Both exhibit good sizing effects due to reaction with hydroxyl groups on pulp fibers, but AKD is more prevalent because ASA is highly hydrolyzable and easily soils the papermaking system.

  AKD is usually used for papermaking in the form of an emulsion using some dispersant. However, due to the reactivity of AKD with water, the emulsion is difficult to store stably for a long time, loses its sizing ability over time, and its mechanical stability is insufficient. Such a problem is easily manifested in an emulsion in which the concentration of AKD is increased in consideration of transportation costs and the like.

  In view of the above problem, Patent Document 1 discloses an emulsion-type sizing agent obtained by emulsifying a predetermined AKD together with a water-soluble aluminum salt in the presence of an anionic group-containing polyacrylamide as a protective colloid. , Storage stability, mechanical stability and size effect are all good.

  However, according to the study by the present applicant, the emulsion-type sizing agent described in Patent Document 1 does not necessarily have the size performance currently required in the field, and also has storage stability and mechanical stability. It turns out that it is not enough.

JP-A-2-19592

  An object of the present invention is to provide an emulsion-type sizing agent using AKD, which has excellent storage stability and mechanical stability, and also has good size properties.

  In order to improve the emulsion type sizing agent described in Patent Document 1, the present inventor firstly has a ketene dimer having a relatively long carbon chain of an alkyl group for the purpose of enhancing its size effect and mechanical stability. AKD containing a large amount of the monomer was selected as the emulsion.

  Then, when the AKD was emulsified, studies were made on a protective colloid that can be stored for a long period of time and can also provide mechanical stability. As a result, surprisingly, it is an anionic group-containing polyacrylamide, which increases the ratio of the sulfo group-containing unsaturated monomer in the anionic unsaturated monomer and has a specific carbon number as the hydrophobic unsaturated monomer. It was found that those using monomers having the above substituents can be successfully used as the intended protective colloids.

  This invention is completed by the said ingenuity, and relates to the emulsion type | mold size agent for paper manufacture shown below, the manufacturing method of paper using the same, and the paper obtained using this.

水溶性アルミニウム化合物（Ｃ）と、
を含有する製紙用エマルジョン型サイズ剤。 1. Anionic vinyl monomer (a1) containing more than 95% by mass of sulfo group-containing unsaturated monomer (a1-1), hydrophobic vinyl monomer (a2) having a hydrocarbon group having 4 to 12 carbon atoms as a substituent An anionic group-containing polyacrylamide (A) which is a reaction product of the monomer group (α) consisting of (meth) acrylamide (a3),
An alkyl ketene dimer (b1) represented by the following general formula (1) (wherein R ₁ and R ₂ are alkyl groups having 14 to 20 carbon atoms and may be the same or different) and the following general formula (1 An alkyl ketene dimer composition (B) containing an alkyl ketene dimer (b2) other than) in a range where the mass ratio [(b1) / (b2)] is 70/30 to 99/1;

A water-soluble aluminum compound (C);
An emulsion type sizing agent for papermaking.

2. (A1-1) The sizing agent according to item 1, wherein the component contains (meth) allylsulfonic acid (salt) and / or styrenesulfonic acid (salt).

3. (A1) The sizing agent according to item 1 or 2, wherein the component further contains α, β unsaturated dicarboxylic acid (salt) (a1-2) in a range of less than 5% by mass.

4). The component (a2) is an alkyl (meth) acrylate (a2-1) having an acyclic alkyl group having 4 to 12 carbon atoms and / or an alkyl (meth) acrylate having a cyclic alkyl group having 6 to 12 carbon atoms (a2- The sizing agent according to any one of Items 1 to 3, comprising 2).

5. (C) The sizing agent according to any one of Items 1 to 4, wherein the component contains aluminum sulfates.

6). The sizing agent according to any one of Items 1 to 5, further comprising a surfactant (D).

7). A method for producing paper, wherein the paper is made by adding the sizing agent according to any one of Items 1 to 6 to a pulp slurry under neutral conditions.

8). Paper obtained by the manufacturing method of said claim | item 7.

  The sizing agent of the present invention is excellent in stability against mechanical share, can be stably stored at a high concentration for a long period of time, and has a good size effect. The sizing agent can be used in any form of a surface sizing agent and an internally added sizing agent, but has a particularly good effect as an internally added sizing agent.

  The paper emulsion type sizing agent of the present invention comprises a predetermined anionic group-containing polyacrylamide (A) (hereinafter also referred to as (A) component), a predetermined alkyl ketene dimer (B) (hereinafter referred to as (B) component). And a water-soluble aluminum compound (C) (hereinafter also referred to as component (C)), and optionally a surfactant (D) (hereinafter also referred to as component (D)). is there.

  The component (A) is a predetermined anionic vinyl monomer (a1) (hereinafter also referred to as (a1) component), a predetermined hydrophobic vinyl monomer (a2) (hereinafter also referred to as (a2) component) and (meta). ) A reaction product of a monomer group (α) (hereinafter also referred to as (α) component) consisting of acrylamide (a3) (hereinafter also referred to as component (a3)).

  The component (a1) contains a sulfo group-containing unsaturated monomer (a1-1) (hereinafter also referred to as the component (a1-1)), and the content is set to be greater than 95% by mass. There is a feature in the point. By doing so, the component (A) according to the present invention contains a relatively large number of sulfo groups as an anionic functional group. As a result, such (A) component is excellent in the dispersibility of the below-mentioned (B) component, and contributes well to all of the size effect of the sizing agent, storage stability, and mechanical stability which concern on this invention. From this viewpoint, the content of the component (a1-1) in the component (a1) is preferably 96% by mass or more, and more preferably 98% by mass or more.

  As the component (a1-1), various known monomers can be used without particular limitation as long as they are polymerizable unsaturated monomers having at least one sulfo group in the molecule. Specific examples include (meth) allyl sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and salts thereof, and two or more thereof can be used in combination. Examples of the compound constituting the salt include sodium hydroxide, potassium hydroxide, ammonia, triethylamine and the like (hereinafter the same applies when referred to as a salt). Among these, it is preferable to use at least (meth) allylsulfonic acid and / or a salt thereof in order to easily adjust the molecular weight of the component (A) and to improve the storage stability of the emulsion according to the present invention.

  The component (a1) may include α, β unsaturated dicarboxylic acid (salt) (a1-2) (hereinafter also referred to as the component (a1-2)). However, as the content increases, the storage stability and mechanical stability of the sizing agent of the present invention tend to deteriorate. Therefore, when the component (a1-2) is used, the content in the component (a1) is preferably less than 5% by mass, preferably less than 4% by mass, and more preferably less than 2% by mass.

  As the component (a1-2), various known monomers can be used without particular limitation as long as they are polymerizable unsaturated monomers having two carboxyl groups in the molecule. Specific examples include maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, fumaric acid, muconic acid, and salts thereof.

  The component (a1) may contain other anionic vinyl monomers (hereinafter also referred to as the component (a1-3)) as necessary. Specifically, for example, α, β-unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid and salts thereof, and phosphoric acid ester group-containing unsaturated monomer such as phosphoric acid ester of (meth) acrylic acid hydroxyalkyl ester. A mass is mentioned. Although the content rate of (a1-3) component in (a1) component is not specifically limited, Usually, it is less than 5 mass%, Preferably it is less than 3 mass%.

  The content of the component (a1) in the component (α) is not particularly limited, but from the viewpoint of balancing the hydrophilicity and hydrophobicity of the component (A) and improving the long-term storage stability of the emulsion according to the present invention, Usually, it is about 5-50 mass%, Preferably it is about 10-30 mass%.

  As the component (a2), various known compounds can be used without particular limitation as long as they are (meth) acrylic acid alkyl esters having an alkyl group having 4 to 12 carbon atoms in the molecule. Specifically, an alkyl (meth) acrylate (a2-1) having an acyclic alkyl group having 4 to 12 carbon atoms (hereinafter also referred to as (a2-1) component) and / or a cyclic group having 6 to 12 carbon atoms. Examples thereof include alkyl (meth) acrylate (a2-2) having an alkyl group (hereinafter also referred to as (a2-2) component).

  Examples of the component (a2-1) include n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl acrylate, octyl ( Examples include meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and the like, and two or more kinds can be used in combination. Among these, those having 6 to 12 carbon atoms in the alkyl group are particularly preferable from the viewpoint of balancing the hydrophilicity and hydrophobicity of the component (A) and improving the long-term storage stability of the emulsion according to the present invention. .

  Examples of the component (a2-2) include cyclohexyl (meth) acrylate, benzyl acrylate, phenoxy (meth) acrylate, and isoboronyl (meth) acrylate, and two or more kinds can be used in combination. Among these, cyclohexyl (meth) acrylate is particularly preferable from the viewpoint of balancing the hydrophilicity and hydrophobicity of the component (A) and improving the long-term storage stability of the emulsion according to the present invention.

  The content of the component (a2) in the component (α) is not particularly limited, but from the viewpoint of balancing the hydrophilicity and hydrophobicity of the component (A) and improving the long-term storage stability of the emulsion according to the present invention, Usually, it is about 5-50 mass%, Preferably it is about 10-40 mass%.

  When the component (a2-1) and the component (a2-2) are used in combination, their mass ratio [(a2-1) / (a2-2)] is not particularly limited, but the hydrophilicity and hydrophobicity of the component (A) From the viewpoint of long-term storage stability of the emulsion according to the present invention, it is usually about 10/90 to 90/10, preferably about 30/70 to 70/30.

  Examples of the component (a3) include acrylamide and / or methacrylamide.

  The content of the component (a3) in the component (α) is not particularly limited, but is usually about 30 to 90% by mass, preferably about 40 to 70% by mass from the viewpoint of improving the long-term storage stability of the emulsion according to the present invention. It is.

  The component (α) may include components other than the components (a1) to (a3) (hereinafter also referred to as (a4) component) as necessary.

  As the component (a4), for example, as a hydrophobic vinyl monomer other than the component (a2), methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, Tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylonitrile, vinyl acetate, α-olefin having about 6 to 22 carbon atoms, vinylpyrrolidone, styrene, α-methylstyrene, vinyltoluene, etc. Is mentioned. Although the content rate of this hydrophobic vinyl monomer in ((alpha)) component is not specifically limited, Usually, it is less than 10 mass%.

  Other components (a4) include tertiary amino groups such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide (meta ) Acrylate, and cationic vinyl monomers such as a reaction product of the tertiary amino group-containing (meth) acrylate and a quaternizing agent. Examples of the quaternizing agent include methyl chloride, benzyl chloride, dimethyl sulfate and epichlorohydrin. However, from the viewpoint of long-term storage stability of the emulsion according to the present invention, the content of the cationic vinyl monomer in the component (α) is usually preferably less than 10% by mass.

  The manufacturing method of (A) component is not specifically limited, Various well-known methods are employable. Specifically, for example, the component (α) may be radically polymerized in a solvent in the presence of an initiator under conditions of about 70 to 140 ° C. and about 1 to 10 hours. Moreover, the addition order of each component which makes ((alpha)) component is not specifically limited, either. Examples of the initiator include azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-methylvaleronitrile, benzoyl peroxide, cumene hydroperoxide, t-butyl. Examples thereof include hydroperoxide, dicumyl peroxide and lauryl peroxide, persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate, and various redox polymerization catalysts. Examples of the solvent include water, benzene, toluene, acetone, methyl ethyl ketone, n-propyl alcohol, and isopropyl alcohol.

  (A) Although the physical property of a component is not specifically limited, From a viewpoint of the long-term storage stability of the emulsion which concerns on this invention, the weight average molecular weight (Polyethylene oxide conversion value by a gel permeation chromatography method) is 2,000-50,000. The viscosity of the 25% by mass solution (in terms of solid content) is about 5 to 600 mPa · s.

The component (B) is an alkyl ketene dimer (b1) represented by the following general formula (1) (wherein R ₁ and R ₂ are alkyl groups having 14 to 20 carbon atoms and may be the same or different). And an alkyl ketene dimer (b2) other than the following general formula (1) in a range in which the mass ratio [(b1) / (b2)] is 70/30 to 99/1.

  Examples of the alkyl group having 14 to 20 carbon atoms include a tetradecyl group, a hexadecyl group, an octadecyl group, and an eicosyl group. These alkyl groups may be branched.

  In addition, as an alkyl group having less than 14 carbon atoms and an alkyl group having more than 20 carbon atoms, for example, a butyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a docosyl group, a tetracosyl group, a hexacosyl group, An octacosyl group etc. are mentioned.

  Like the component (B), an AKD containing a large amount of ketene dimer derived from a fatty acid having a relatively large number of carbon atoms is usually difficult to emulsify. However, in the case of the present invention, the predetermined component (A) Therefore, an emulsion excellent in both storage stability and mechanical stability can be obtained.

The carbon number of R ₁ and R ₂ can be measured by various known methods using a pyrolysis gas chromatograph / mass spectrometer.

  As the component (C), various known compounds can be used without particular limitation as long as they are water-soluble aluminum compounds used as auxiliary materials for sizing agents. Specific examples include aluminum sulfates such as aluminum sulfate, basic aluminum sulfate and aluminum sulfate oxalate; aluminum chlorides such as aluminum chloride and basic aluminum chloride; aluminum nitrate and the like. it can. Among these, aluminum sulfates are particularly preferable in consideration of economy and versatility.

  As the component (D), various known surfactants can be used. Specifically, an anionic surfactant and a nonionic surfactant are mentioned, for example.

  Examples of the anionic surfactant include dialkyl sulfosuccinate, alkane sulfonate, α-olefin sulfonate, polyoxyethylene alkyl ether sulfosuccinate, polyoxyethylene styryl phenyl ether sulfosuccinate, naphthalene. Examples include sulfonate formalin condensate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polystyrene sulfonate, and the like.

  Examples of nonionic surfactants include polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene sorbitan fatty acid ester, sugar ester, and the like.

In the emulsion type sizing agent according to the present invention, the content of the component (A), the component (B) and the component (C) is not particularly limited. However, in consideration of the balance of the intended effect of the present invention, usually, (All solid content conversion). The emulsion type sizing agent of the present invention is also characterized by a relatively high content of component (B) and a high concentration.
(A) Component: about 3 to 20% by mass, preferably about 5 to 15% by mass (B) Component: about 80 to 95% by mass, preferably about 83 to 90% by mass (C) Component: 0.05 to 1 About mass%, preferably about 0.1 to 0.5 mass%

  Further, the content of the component (D) is not particularly limited, but is generally about 0.05 to 5% by mass, preferably 0.5 to 2% by mass from the viewpoint of improving the long-term storage stability of the emulsion according to the present invention. %.

  The sizing agent of the present invention may contain trimellitic acid trialkyl ester from the viewpoint of improving storage stability. The number of carbon atoms of the alkyl group is not particularly limited, but is usually about 8 to 10. Specific examples of the ester include triisodecyl trimellitic acid, trinormal decyl trimellitic acid, tri-2-ethylhexyl trimellitic acid, and trinormal octyl trimellitic acid. On the other hand, the trimellitic acid trialkyl ester is unclear for a detailed reason, but when the sizing agent of the present invention is used in an internal addition mode, the size effect of the obtained paper tends to be impaired. Therefore, the amount used is usually less than 1 part by mass, preferably less than 0.1 part by mass, and more preferably less than 0.01 part by mass with respect to 100 parts by mass of component (B).

  The sizing agent of the present invention can be produced by various known methods. Specifically, for example, by adding the component (B), the component (C) and, if necessary, the component (D) simultaneously or sequentially to the solution of the component (A), and stirring and mixing by a known means, The desired emulsion type sizing agent is obtained. Examples of the stirring / mixing means include a homomixer, a high-pressure discharge type homogenizer, and an ultrasonic emulsifier.

  Various additives may be included in the sizing agent of the present invention. Specific examples include antifoaming agents, anti-slip agents, antiseptics, rust preventives, thickeners, pH adjusters, antioxidants, film increasing aids, pigments, dyes, and starches. Examples of the starch include oxidized starch, phosphate esterified starch, enzyme-modified starch, APS-modified starch, cationized starch, and amphoteric starch.

  The sizing agent of the present invention has a milky white appearance, the viscosity at a solid content concentration of 30% by mass is usually about 3 to 100 mPa · s, the pH is usually about 3 to 6, and the average particle size (laser diffraction / scattering type) The measured value by a particle size measuring device) is usually about 0.3 to 2 μm.

  The sizing agent of the present invention can be used as either a surface sizing agent or an internally added sizing agent, but exhibits the desired size effect particularly when used as an internally sizing agent.

The surface sizing means is not particularly limited, and various known methods can be employed. Examples of the coating means include an impregnation method, a bar coater method, a calendar method, a spray method, a method such as a two-roll size press, and a film transfer method such as a gate roll size press and a shim size press. Moreover, although the coating amount of the sizing agent of this invention is not specifically limited, Usually, it is about 0.001-2g / m < ² > (solid content) in conversion of solid content. The paper to be coated is not particularly limited, and examples thereof include newspaper, writing paper, wallpaper, PPC paper, inkjet paper, printing paper, liner, and core.

  The means for internal addition sizing is not particularly limited, and various known methods can be employed. Specifically, the sizing agent of the present invention is added to a pulp slurry together with a filler, a fixing agent, a paper strength enhancer, a filler retention agent, and, if necessary, the component (C), and then papermaking is performed by conventional means. Can be done. The addition amount of the sizing agent is not particularly limited, but is usually about 0.01 to 2.0% by mass, preferably about 0.05 to 1.0% by mass, based on the pulp, in terms of solid content. Further, the pH of the papermaking system is not particularly limited, but since the sizing agent of the present invention is suitable for neutral papermaking, the pH is usually about pH 6 to 9, preferably about 7 to 8.

  A paper strength enhancer can be used in combination for both surface sizing and internal sizing. Specifically, for example, cationized starch, polyamide polyamine resin epichlorohydrin modified product, dicyandiamide resin epichlorohydrin modified product, styrene-dimethylaminoethyl methacrylate copolymer epichlorohydrin modified product, polyacrylamide Mannich modified product, acrylamide-dimethyl Examples thereof include aminoethyl methacrylate copolymers, polyacrylamide Hofmann degradation products, and copolymers of dialkyl diallylammonium chloride and sulfur dioxide.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to these examples. In each example, all parts and% are based on mass unless otherwise specified. The physical property value of each example is a value measured by the following method.

(viscosity)
It is a measured value at 25 ° C. using a Brookfield rotational viscometer (manufactured by Tokyo Keiki Co., Ltd., VISCOMETER).

(Synthesis of component (A))
Synthesis example 1
In a flask equipped with a stirrer, a condenser, a dropping funnel, a nitrogen inlet tube and a thermometer, 115.2 g of acrylamide, 27.0 g of sodium methallylsulfonate, 14.4 g of 2-ethylhexyl acrylate, 23.4 g of cyclohexyl methacrylate, isopropyl alcohol 272.7 g and ion-exchanged water 256.3 g were charged, and the mixture was heated to 50 ° C. under nitrogen gas bubbling while stirring. 18.3 g of 10% aqueous solution of ammonium persulfate was added, the temperature was raised to 80 ° C. and kept at the same temperature for 3 hours, and then diluted by adding 205.0 g of ion exchange water, isopropyl alcohol was distilled off, the concentration was adjusted, An anionic group-containing polyacrylamide (A) having a solid content concentration of 25% was obtained. Table 1 shows the viscosities immediately after synthesis of the component (A).

Synthesis Examples 2-14, Comparative Synthesis Examples 1-7
In Production Example 1, an anionic group-containing polyacrylamide was synthesized in the same manner as in Production Example 1 except that the types and amounts of the respective components were changed to Table 1.

SMAS: sodium methallyl sulfonate NASS: sodium styrene sulfonate IA: itaconic acid 2EHA: 2-ethylhexyl acrylate BA: butyl acrylate CHA: cyclohexyl acrylate CHMA: cyclohexyl methacrylate AM: acrylamide DM: dimethylaminoethyl methacrylate

Example 1
350 g of alkyl ketene dimer (from a mixture of 5% palmitic acid chloride and 95% stearic acid chloride) (described as C18 in Table 2), 226 g of Synthesis Example 1 as component (A), surfactant (naphthalene) 10.5 g of 40% aqueous solution of sodium sulfonate formalin condensate (trade name “Demol NL”, manufactured by Kao Corporation), 16.9 g of aluminum sulfate aqueous solution (containing 8% as Al ₂ O ₃ ), 48% sodium hydroxide aqueous solution After charging 5.3 g and 399 g of deionized water, heating to 70 to 80 ° C. and pre-dispersing with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), then under the condition of 40 MPa at the same temperature The mixture was forcedly dispersed twice by passing through a high-pressure homogenizer (APV, manufactured by Gaulin). Then, it cooled to 25 degreeC and diluted with water, and obtained the emulsion type sizing agent of solid content concentration 30%. Immediately after the production, the viscosity at 25 ° C. was measured using a B-type viscometer after placing the sample in a 225 ml mayonnaise bottle. The results are shown in Table 2.

Examples 2 to 21 and Comparative Examples 1 to 9
Using the types and amounts used in Table 2 of component (A) and component (B), component (C), surfactant, and trimellitic acid trialkyl ester (C8, C10), Example 1 and An emulsion type sizing agent was obtained in the same procedure. Further, the viscosity at 25 ° C. of each sizing agent was measured in the same manner as in Example 1. However, the sizing agent of Comparative Example 5 was in the form of a highly viscous cream and could not be measured. Further, in Example 18 and Comparative Example 1, as the component (B), a mixture (described as C16 / C18 in Table 2) using a mixture of 35% palmitic acid chloride and 65% stearic acid chloride was used. In Example 17, the component (B) used was a mixture of 90% behenic acid chloride and 10% stearic acid chloride (described as C22 in Table 2).

(Storage stability)
About each emulsion type sizing agent of the said Example and a comparative example (except the thing of the comparative example 5. Hereafter, it is the same.) Put a sample in a 225 ml mayonnaise bottle, and the viscosity (B type after storing at 30 degreeC for one month) Viscometer: 25 ° C.) was measured.

(Mechanical stability)
50 g of the emulsion sizing agent of Example 1 above was weighed into a container of a Marlon stability tester (manufactured by Shinsei Sangyo Co., Ltd.), temperature 25 ° C., load 10 kg, rotation speed 1000 r. p. m. After adding a mechanical shear for 5 minutes, the resulting aggregate was removed with a 350 mesh wire mesh, and the mechanical stability was calculated according to the following equation. The mechanical stability of the emulsion type sizing agents of other examples and comparative examples was similarly evaluated.

Mechanical stability (%) = (absolute dry mass of aggregate / absolute dry mass of sample emulsion sizing agent) × 100

(Size performance evaluation)
To L-BKP, tap water having an amount of pulp solid content of 2.0% was added and beaten using a Niagara beater until 345 ml Canadian Standard Freeness was achieved. Next, the beaten pulp slurry was further diluted with tap water to adjust the pulp solid content concentration to 1.0%. To this pulp slurry, the emulsion sizing agent according to Example 1 was added in an amount of 0.12% (solid content) with respect to the pulp solid content. Further, light calcium carbonate in an amount of 10% (solid content) with respect to the pulp solid content (Tama Pearl TP-121 manufactured by Okutama Kogyo Co., Ltd.) and a sulfate band in an amount of 1.0% (solid content) (Alum) (Wako Pure Chemical Industries, Ltd., aluminum sulfate, 14-18 hydrate), and commercially available cationized starch in an amount of 0.5% (solid content) (Oji Cornstarch Co., Ltd.) Oji Ace K-100) and a yield improver (Percoll 47 (cationic polyacrylamide polymer) manufactured by Kyowa Sangyo Co., Ltd.) in an amount of 0.01% (solid content) were further added. Thereafter, hand-made paper was prepared with a standard sheet machine paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd.) so that the basis weight was 70 g / m ² . The papermaking pH at this time was 7.8 to 8.0. The hand-wetted wet paper was press-dehydrated with a load of 3.5 kgW / cm ² for 2 minutes and then dried with a rotary dryer at 100 ° C. for 1 minute. After drying, after conditioning for 24 hours in a constant temperature and humidity chamber (23 ° C., 50% relative humidity), the basis weight is 70.2 ± 0.5 g / m ² and the density is 0.57 ± 0.5 g / cm ³ . A test paper was obtained and subjected to the following evaluation. The same number of test papers were obtained in the same manner for the emulsion type sizing agents of other examples and comparative examples.

(Paper quality evaluation)
The basis weight was measured according to JIS P 8124, and the density was measured according to JIS P 8118.

(Performance evaluation)
Steech human sizing degree: Measured based on JIS P 8122.

Claims (8)

Anionic vinyl monomer (a1) containing more than 95% by mass of sulfo group-containing unsaturated monomer (a1-1), hydrophobic vinyl monomer (a2) having a hydrocarbon group having 4 to 12 carbon atoms as a substituent An anionic group-containing polyacrylamide (A) which is a reaction product of the monomer group (α) consisting of (meth) acrylamide (a3),
An alkyl ketene dimer (b1) represented by the following general formula (1) (wherein R ₁ and R ₂ are alkyl groups having 14 to 20 carbon atoms and may be the same or different) and the following general formula (1 An alkyl ketene dimer composition (B) containing an alkyl ketene dimer (b2) other than) in a range where the mass ratio [(b1) / (b2)] is 70/30 to 99/1;

A water-soluble aluminum compound (C);
An emulsion type sizing agent for papermaking. The sizing agent according to claim 1, wherein the component (a1-1) comprises (meth) allylsulfonic acid (salt) and / or styrenesulfonic acid (salt). The sizing agent according to claim 1 or 2, wherein the component (a1) further comprises an α, β unsaturated dicarboxylic acid (salt) (a1-2) in a range of less than 5% by mass. The component (a2) is an alkyl (meth) acrylate (a2-1) having an acyclic alkyl group having 4 to 12 carbon atoms and / or an alkyl (meth) acrylate having a cyclic alkyl group having 6 to 12 carbon atoms (a2- The sizing agent according to claim 1, comprising 2). The sizing agent according to any one of claims 1 to 4, wherein the component (C) contains aluminum sulfates. The sizing agent according to any one of claims 1 to 5, further comprising a surfactant (D). A paper manufacturing method, wherein the paper is made by adding the sizing agent according to any one of claims 1 to 6 to a pulp slurry under neutral conditions. Paper obtained by the production method according to claim 7.