JPH10212697A - Surface-sizing composition for paper making and surface-sizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition that can reduce foaming and staining in a coating system and can improve its operability, even when the coating solution is prepared by admixing a surface strength-improving agent to the composition, by dispersing the phase to be dispersed (dispersion phase) containing ketene dimer and a specific fatty acid in a disperse (matrix) phase containing water and protective colloid. SOLUTION: (A) The phase to be dispersed containing ketene dimer, of the formula (R<1> and R<2> are independently hydrocarbon group residues of 8-30 carbon atoms) and a specific fatty acid in an amount of 3-10wt.% on the solid basis is dispersed in the matrix (disperse) phase containing water and protective colloid. The fatty acid to be added to the phase to be dispersed is a 12-24C saturated fatty acids as tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid or tetracosanoic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface sizing composition for papermaking and a method for sizing the surface of paper using the same.

[0002]

2. Description of the Related Art In recent years, neutral sizing has been introduced from the viewpoints of making white water closed in a paper making process, using inexpensive calcium carbonate having a high degree of whiteness as a filler, and coat-broking. As the sizing agent used for this neutral sizing, conventionally, substituted cyclic dicarboxylic anhydrides, ketene dimer compounds, copolymers of cationic monomers and hydrophobic monomers, cationized petroleum resins, cationized fatty acid amides, etc. Among them, ketene dimer sizing agents are widely used because of their simplicity in use and the ability to impart strong sizing properties with a small amount of addition (JP-B-63-38479, JP-B-1). -2
No. 7200).

[0003] In addition, the sizing method includes an internal sizing method and a surface sizing method. When a ketene dimer sizing agent is used as a surface sizing agent, it is necessary to increase the surface strength of paper to improve printability. For the purpose, a mixed solution for coating is often prepared in combination with a surface strength improver such as oxidized starch.

[0004]

However, the mixed solution for coating has foaming properties due to the surface strength improver. If the foaming of the mixture for coating is remarkable, dirt may be generated in a system such as a vibrating screen or a closed screen provided for removing foreign substances in the sizing agent, and the operability and the obtained paper may be reduced. There is a problem such as a decrease in quality. The present invention seeks to solve such a problem.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems. As a result, in the solid content of the dispersed phase of the aqueous emulsion type ketene dimer sizing agent, according to the papermaking surface sizing composition containing a specific amount of a fatty acid as a ketene dimer raw material,
When a coating solution comprising the sizing composition and a surface strength improver is used, unexpectedly, due to the defoaming action of the added fatty acid, foaming in the coating system and generation of dirt in the system are reduced,
It has been found that operability can be greatly improved. The present invention has been completed based on such new findings.

That is, the present invention relates to a ketene dimer paper surface sizing composition comprising a ketene dimer-containing dispersed phase and water and a protective colloid-containing dispersed phase, wherein the solid content in the dispersed phase is as follows: , Having 10 to 3 carbon atoms
The present invention relates to a paper sizing composition containing 3 to 10% by weight of the fatty acid 2. The present invention also resides in a surface sizing method, which comprises using the above-described surface sizing composition for papermaking.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The ketene dimer used in the present invention is not particularly limited, and a known ketene dimer can be used. The ketene dimer has the general formula:

Embedded image (Wherein R ¹ and R ² each represent a hydrocarbon residue having 8 to 30 carbon atoms, preferably 10 to 22 carbon atoms).
Examples of R ¹ and R ² include an alkyl group, an alkenyl group, and an aryl group. Specific examples include alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and eicosyl groups, and alkenyl groups such as decenyl, tridecenyl, hexadecenyl, octadecenyl and eicosenyl groups. These ketene dimers can be used alone or as a mixture. Further, even those synthesized from natural fatty acids, tallow oil, hardened tallow oil, etc. may be used.

As the fatty acid having 10 to 32 carbon atoms, various saturated or unsaturated fatty acids can be mentioned. Specifically, examples of the saturated fatty acid include decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), and eicosanoic acid ( Arachiic acid), docosanoic acid (behenic acid), tetraconic acid (lignoceric acid), octacosanoic acid (montanic acid), and triacontanic acid (melicic acid). Examples of unsaturated fatty acids include palmitoleic acid, oleic acid, linoleic acid, linoleic acid, erucic acid and the like. Among these fatty acids, carbon such as tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachinic acid), docosanoic acid (behenic acid), and tetracosanoic acid (lignoceric acid) Saturated fatty acids of numbers 12 to 24 are preferred.
Each of these fatty acids can be used alone or as a mixture of a plurality of fatty acids.

As described above, the surface sizing composition for papermaking of the present invention is characterized in that a specific amount of fatty acid is contained in the solid content of the phase to be dispersed of the ketene dimer sizing agent. That is, the amount of the fatty acid used is 3 to 10% by weight, preferably 4 to 8% by weight of the solid content in the dispersed phase in the ketene dimer sizing agent. When the amount of the fatty acid used is less than 3% by weight, the effect of suppressing foaming and preventing stains is small, and does not contribute to improvement in operability. If the used amount of the fatty acid exceeds 10% by weight, the size performance is reduced, and it is difficult to obtain the required paper quality. In addition, fatty acids are
It may be added separately to the ketene dimer, or a predetermined amount of the raw material fatty acid may remain during the production of the ketene dimer.

The ketene dimer sizing agent can be produced by a conventionally known method. For example, ketene dimer (containing fatty acid) and protective colloid are mixed in a hot water solvent,
It is obtained by uniformly dispersing with a known mixer such as a homomixer or a high-pressure discharge homogenizer.

Known protective colloids can be used. Examples thereof include cationic dispersants such as cationized starch, nonionic dispersants such as polyvinyl alcohol and oxidized starch, and anionic dispersants such as ligninsulfonate and naphthalenesulfonate formaldehyde condensate. These can be used alone or in combination of two or more.

The obtained ketene dimer sizing agent has a solid concentration of about 10 to 30% by weight. The weight ratio of the dispersed phase / dispersed phase is usually 50 to 96/50 to 50
4. The viscosity is 100 cps or less, and the pH is 6.
It is preferably 5 or less.

The paper sizing composition containing the ketene dimer sizing agent thus obtained is usually used in combination with a surface strength improver such as an oxidized starch paste solution or an aqueous polyvinyl alcohol solution. Is prepared as a mixture. In the mixed solution for coating, the surface sizing composition for papermaking is about 0.005 to 1% by weight (solid content), and the surface strength improver is about 1 to 20% by weight (solid content). In preparing the mixture for coating, a water-soluble polymer-type sizing agent such as a styrene-maleic acid copolymer may be used in combination.

The means for sizing the paper surface using the paper-making surface sizing composition is not particularly limited, and various means can be employed. Specifically, it is applied by a size press, a gate roll coater, a bill blade, a calender or the like. The coating amount of the coating mixture is not particularly limited, but usually the coating amount of the papermaking surface sizing composition contained in the mixture is 0.003 to 1 g / m ² (dry weight). , Preferably 0.01 to 0.2 g / m ² . In addition, the type of base paper to be surface-sized is not particularly limited. Paper using ordinary pulp raw materials, ie bleached or unbleached high-yield pulp such as kraft pulp, sulfite pulp, etc., bleached or unbleached chemical pulp, groundwood pulp, mechanical pulp, thermomechanical pulp, etc. Any paper using waste paper pulp, such as waste paper, corrugated paper, and deinked waste paper, can be used.

According to the surface sizing composition for papermaking of the present invention, even when a coating solution used in combination with a surface strength improver is used, a predetermined amount of ketene dimer sizing agent is contained in the dispersed phase. Since the fatty acid acts like an antifoaming agent, foaming and contamination in the system are reduced, and operability and quality of the obtained paper are improved.

[0016]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. All percentages are based on weight. Example 1 872 g of a mixed solution of cationized starch and sodium naphthalenesulfonate-formaldehyde condensate previously gelatinized at 90 ° C. for 1 hour (as solids, 30.4 g of cationized starch and sodium naphthalenesulfonate-formaldehyde condensate 1) .6 g), and 128 g of molten ketene dimer as a phase to be dispersed.
(Composition ratio: stearic acid 65%, palmitic acid 30%,
A mixture of free fatty acids (composition ratio: 65% of stearic acid, 30% of palmitic acid, 5% of myristic acid, 3% by weight) obtained by using 5% of myristic acid as a raw material was mixed at 75 ° C. Using a high-pressure discharge homogenizer, the mixture was emulsified at a pressure (gauge pressure) of 300 kg / cm ² and further cooled to obtain a ketene dimer sizing agent. Solids concentration 16%, viscosity 6 centipoise, pH 4.5
Met.

Examples 2-5, Comparative Examples 1-2 Ketene dimer sizing agents were obtained in the same manner as in Example 1, except that the content of free fatty acids in ketene dimer was changed as shown in Table 1. . The ketene dimer used in each of these examples was prepared from the same raw material as the fatty acid raw material for producing the ketene dimer described in Example 1; Only the free fatty acid content in the dimer (note that
The composition ratio of the free fatty acid in each ketene dimer is also the same as that in the ketene dimer of Example 1).

[0018]

[Table 1]

The ketene dimer sizing agents obtained in Examples and Comparative Examples were filtered through a 350 mesh wire gauze, but there were almost no filtration residues.
Was less than.

<Evaluation of Performance> As shown in Table 2, ketene dimer-based sizing agents, surface strength improvers, and water-soluble polymer sizing agents of different types and amounts were used to prepare mixed liquids for coating. All figures are% by weight solids. As a water-soluble polymer type sizing agent in Table 2, a styrene-maleic acid copolymer was used.

[0021]

[Table 2]

The following performance evaluations were performed on the surface sizing compositions for papermaking obtained in Examples and Comparative Examples. Table 3 shows the evaluation results.

(Foamability)-<Mixer foamability test> 0.25 g of light calcium carbonate was added to 500 g of the mixture for coating shown in Table 2, and the mixture was adjusted at 70 ° C. and placed in a 1-liter beaker kept warm. The mixture was whipped for 5 minutes using a hand mixer (Matsubara Corp .; MS-101H).
Immediately transfer the foamed liquid to a 1-liter graduated cylinder,
The total liquid volume in which the liquid and the foam were mixed was measured. Table 3 shows the results. The reason for adding and evaluating light calcium carbonate is to reproduce the effect of the light calcium carbonate contained in the base paper migrating into the coating liquid at the experimental level in the surface sizing in the actual machine. .

(Agglomerate adhesion amount) --- <In-line filter test> 12.5 g of light calcium carbonate was added to 2.5 kg of the mixture for coating shown in Table 2, and the temperature was adjusted and maintained at 70 ° C. Using the set in-line filter, a circulation test was performed at a flow rate of 5 liters / minute for 1 hour, aggregates on the filter surface were scraped off from the filter surface, and the weight was measured after drying. Table 3 shows the results. In addition,
This indicates that the larger the amount of aggregates attached, the more easily stains occur in the system. The evaluation with the addition of light calcium carbonate is based on the same reason as shown in the foaming test.

(Paper sizing properties) A mixture of the paper sizing agent composition and the oxidized starch and / or PVA shown in Table 2 was converted into a neutral, weakly sized paper by a lab size press. After coating, the paper was measured for the degree of Stechig sizing. Table 3 shows the obtained results. Each papermaking condition,
The sizing conditions and measurement conditions of the sizing test are shown below.

(1) Base paper Pulp: LBKP (Canadian standard freeness 400 ml) Filler: Light calcium carbonate (Tamapearl 121,
Okutama Kogyo Co., Ltd.), adjusted so that calcium carbonate in paper becomes 12% Fixing agent: cationized starch (CATO302, manufactured by Oji National), solid content 0.5% based on pulp weight Sizing agent: ketene dimer system Sizing agent (size pine K
-902-20 Arakawa Chemical Co., Ltd.), solid content 0.05% based on pulp weight Yield improver: Cationic polyacrylamide polymer (Percoll 47, manufactured by Kyowa Sangyo), solid content 0.02% based on pulp weight PH: 8.0 Order of addition: Pulp-filler-fixing agent-sizing agent-yield improver Paper making: Tappy square hand-making machine Press: 3.5 kgW / cm ² × 2 minutes Drying: rotary dryer, 100 ° C / 40 seconds Basis weight: 70g / m ²

(2) Size press Pressing speed: 100 m / min Nip pressure: 10 kg / cm Coating temperature: 60 ° C. Coating amount of coating mixture: about 30 g / m ² (3) Drying condition Using a rotary dryer And dried at 105 ° C. for 40 seconds.

(4) Sizing test: Stekihito sizing test (JIS P-8122) Four sides of the test paper were bent upward to form a boat, and 2% NH ₄
1% FeC from above while floating on SCN aqueous solution
dropped l ₃ aqueous solution to drop test paper, two solutions was measured the time (seconds) until spots red thiocyanate iron contact to penetrate the paper 3 appears.

[0029]

[Table 3]

[0030]

As is clear from Table 3, Evaluation Examples 1 to 1
Sizing composition of the present invention found in No. 5 (Examples 1 to 5)
Were evaluated using the ketene dimer sizing agent (Comparative Examples 1 and 2) to which no fatty acid was added.
Compared to the case of 0, even when the surface strength improver is used in combination, foaming is small, and the amount of aggregates that cause stains in the system is small.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masato Nakajima 3-4-133 Imafukuminami, Joto-ku, Osaka-shi, Osaka Arakawa Chemical Industry Co., Ltd. (72) Inventor Jun Ikeda Imafuku-minami, Joto-ku, Osaka-shi Arakawa Chemical Industry Co., Ltd.

Claims (2)

[Claims] 1. A dispersed phase containing a ketene dimer,
In the ketene dimer paper surface sizing composition comprising a dispersed phase containing water and a protective colloid, a fatty acid having 10 to 32 carbon atoms as a solid content in the dispersed phase is 3-1 to 1 as a solid content.
A surface sizing composition for papermaking containing 0% by weight. 2. A paper surface sizing method, comprising using the papermaking surface sizing composition according to claim 1.