JP2806563B2 - Sizing composition for papermaking - Google Patents

Description

The present invention relates to a sizing composition for papermaking. More specifically, a novel ketene dimer sizing composition that is effective in the neutral or higher pH range, has a high concentration, good storage stability and dispersion stability, and does not require time to develop the sizing effect. It is about things.

[Conventional technology]

Conventionally, saponified rosin size and emulsion rosin size have been used as sizing agents for papermaking, and aluminum sulfate has been used as a fixing agent. However, the use of aluminum sulfate lowers papermaking pH, causing problems such as corrosion of papermaking machinery, contamination of wastewater, deterioration of paper, and restrictions on diversified paper quality. Another problem is that the use of calcium carbonate, which is produced in large quantities and is inexpensive in Japan, as a filler is restricted.

Therefore, development of a neutral sizing agent has been promoted in order to solve the above-mentioned problem of the rosin-based sizing agent-aluminum sulfate.

As a result, ketene dimer compounds, succinic anhydride compounds, copolymers of cationic monomers and hydrophobic monomers, cationized petroleum resins, cationized fatty acid amides, etc. are currently being developed and marketed as neutral sizing agents. Among them, ketene dimer compounds are considered to be the most effective and are widely used.

[Problems to be solved by the invention]

However, the ketene dimer sizing agent has a problem that it takes time to develop the size effect. Although this problem is pointed out by the expression "poor start-up", when the aqueous working fluid is applied to paper immediately after sizing with a ketene dimer sizing agent, the size effect is still insufficient. Since it does not appear, the amount of liquid absorption of the aqueous processing liquid is increased, which causes a problem that the application amount cannot be controlled.

In addition, the sizing composition must be given sufficient consideration for stability, but ketene dimer compounds are generally used by dispersing them in a colloidal form in an aqueous continuous phase containing starch, particularly cationized starch. However, at that time, there is a problem that it is very difficult to obtain a stable aqueous dispersion because the ketene dimer compound is a substance having high reactivity with water. Thus, there is the disadvantage that the dispersion loses homogeneity during storage, gelling or precipitation occurs, or the size effect is attenuated by hydrolysis of the ketene dimer over time.

Further, there is a problem in that the concentration of the emulsion cannot be increased due to poor dispersion stability, so that the cost of transporting and filling the product is increased, and the cost is disadvantageous.

In order to solve these problems, Japanese Patent Application Laid-Open No. 58-197397
Japanese Patent Laid-Open Publication Nos. Sho 59-26592, Sho 60-88196, and the like have been proposed, but none of them have been able to obtain a sufficient effect yet.

For these reasons, the use of conventional sizing compositions is currently limited.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, using a starch derivative having a higher cationic property than in the past, the cationic starch derivative and an anionic dispersant were dissolved in water together with a ketene dimer. It has been found that by blending, a sizing composition having a good rise in size, a high concentration, and excellent storage stability and dispersion stability can be obtained, and the present invention has been completed.

That is, the present invention provides (A) a ketene dimer compound represented by the following general formula (I), (Wherein R ₁ and R ₂ represent the same or different hydrocarbon groups having 8 to 30 carbon atoms.) And (B) a process wherein the degree of substitution (DS) of the cationic group per anhydroglucose unit is in the following range: It is an object of the present invention to provide a papermaking sizing composition comprising an aqueous dispersion containing starch, 0.1 <DS ≦ 1.0 and (C) an anionic dispersant having a sulfonic acid group or a sulfate group.

As the ketene dimer compound used in the present invention,
It is a compound represented by the above general formula (I), and any of various known ketene dimer compounds can be used. In the general formula (I), R ₁ and R ₂ represent the same or different hydrocarbon groups having 8 to 30 carbon atoms. Examples of the hydrocarbon groups include decyl, dodecyl, tetradecyl, hexadecyl,
Examples include alkyl groups such as octadecyl and eicodecyl, alkenyl groups such as tetradecenyl, hexadecenyl and octadecenyl, alkyl-substituted phenyl groups such as octylphenyl and nonylphenyl, alkyl-substituted cycloalkyl groups such as nonylcyclohexyl, and aralkyl groups such as phenylethyl. Of these, an alkyl group is preferred. These ketene dimer compounds are used alone or in combination of two or more.

In order to obtain the cationized starch used in the present invention, potato starch, corn starch, tapioca starch, wheat starch and other starches can be used as the raw starch.

Moreover, in order to increase the concentration of the sizing composition for papermaking, the cationic starch derivative must be reduced in molecular weight. Examples of the method for reducing the molecular weight include a method of hydrolyzing with a mineral acid such as hydrochloric acid and sulfuric acid, a method of oxidizing with an oxidizing agent such as sodium hypochlorite, hydrogen peroxide and cutting the molecule.

The cationic group may be a 3-chloro-2-hydroxypropyltrimethylammonium chloride, a glycidyltrimethylammonium chloride, a diethylaminoethyl in the presence of an alkali metal or alkaline earth metal hydroxide or an alkali substance such as quaternary ammonium hydroxide. It can be introduced by reacting a raw material starch with a cationizing agent such as chloride.

The degree of this cationization, when expressed as the degree of substitution DS (DS = the number of moles of the substituent per mol of anhydrous glucose), must satisfy 0.1 <DS ≦ 1.0.

When preparing a sizing composition using the modified starch of the present invention, the viscosity of the starch paste is preferably 5 to 3000 centipoise when a 4% by weight aqueous solution is measured at 25 ° C. with a BM viscometer.

The processed starch is required to have high size liquid stability. Conventionally, in order to increase the stability of size liquid, in addition to cationization reaction, introduction of nonionic group by etherification and esterification reaction,
Further, an operation for removing inorganic ions was required. However, the processed starch has not only improved sizing stability, storage stability, and dispersion stability only by the cationization reaction when the degree of substitution exceeds 0.1, but also increases the degree of sizing. Contribute. When the degree of substitution exceeds 1.0, the yield of the cationization reaction is significantly reduced, which is economically disadvantageous.

The anionic dispersant may be selected from the group consisting of sulfonic acid groups, sulfate groups, and salts thereof.
It is a kind or a mixture of two or more kinds. Specifically, dialkyl sulfosuccinate, (hydroxy) alkane sulfonate, alkylbenzene sulfonate,
Alkyl naphthalene sulfonate, alkyl phenoxy polyoxyethylene propyl sulfonate, polyoxyethylene alkyl-sulfophenyl ethers, N-methyl-N-oleyltaurine sodium, N-alkyl sulfosuccinate monoamide disodium salt, lignin sulfonate , (Alkyl) naphthalene sulfonate-formaldehyde condensate, sulfate of fatty acid alkyl ester, alkyl sulfate, polyoxyethylene alkyl ether sulfate, fatty acid monoglyceride sulfate, polyoxyethylene alkyl phenyl ether sulfate And polyoxyethylene styryl phenyl ether sulfate.

The constituent ratio of each component of the sizing composition of the present invention is 5 to 30% by weight for the ketene dimer, 10 to 100% by weight based on the ketene dimer for the modified starch, and ketene for the anionic dispersant. 0.1 to 10 for dimer
% By weight.

The sizing composition of the present invention can be produced by various known and commonly used production methods. For example, a ketene dimer compound, a processed starch having a cationic group and an anionic dispersant are mixed in an aqueous medium at a temperature equal to or higher than the melting point of the ketene dimer compound, and a homomixer, a high-pressure discharge homogenizer, an ultrasonic emulsifier, or the like is used. Or a ketene dimer compound is dissolved in a water-insoluble organic solvent such as toluene, dichloroethane, etc., and mixed in an aqueous medium containing a processed starch having a cationic group and an anionic dispersant; A method in which the water-insoluble organic solvent is distilled off under reduced pressure after uniformly dispersing with a high-pressure discharge homogenizer, an ultrasonic emulsifier or the like can be used.

It is desirable that the particle size of the dispersed phase of the sizing composition obtained by the above-mentioned method is 5 μm or less, preferably 2 μm or less. If the particle size of the dispersed phase is too large, the dispersion system tends to lose uniformity during storage. In particular, when the particle size is 5 microns or more, a ketene dimer-based aqueous dispersion having a high concentration and excellent storage stability is used. Hard to get.

The sizing composition thus obtained can be used by a conventionally known method. That is, either one of the internal sizing method and the surface sizing method may be used, or both may be used simultaneously.

When the internal sizing method is used, the sizing composition for papermaking of the present invention is added to the aqueous dispersion of pulp in an amount of 0.02 to 3 solids% by weight, preferably 0.05 to 3% by dry weight of the pulp.
Add ~ 2 solids wt%.

Pulp raw materials include bleached or unbleached pulp such as kraft pulp and sulfite pulp, unbleached chemical pulp, groundwood pulp, mechanical pulp, thermomechanical pulp, etc. Any of used paper pulp such as deinked used paper can be used.

Additives such as fillers such as calcium carbonate, talc, and titanium oxide, dyes, dry paper strength improvers, wet paper strength improvers, retention aids, and the like may be used as necessary. In addition, starch, polyvinyl alcohol, size press, gate roll coater, bill blade coater, calender, etc.
Dyes, coating colors, surface sizing agents, anti-slip agents, etc. may be applied as needed.

When used for the surface sizing method, size press, gate roll coater, bill blade coater,
The sizing composition for papermaking of the present invention may be added to a surface coating liquid applied by a calender or the like so that 0.005 to 0.5 g / m ² (dry weight) is applied to the paper surface.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples, Comparative Examples, and Production Examples, but the present invention is not limited to these Examples. In the Examples, Comparative Examples and Production Examples,% means% by weight unless otherwise specified, and parts means parts by weight.

Further, the stability test and the size effect test were performed and evaluated as follows.

[Stability Test] With respect to the sizing compositions obtained in the respective Examples and Comparative Examples, the dispersion state of the sizing agent after being left at 5, 20, and 32 ° C. for one month was examined. The results are shown in Tables 1 and 2. The evaluation criteria for the stability test are as follows.

 A: The viscosity is stable, and no aggregation between particles is observed.

：: Viscosity is stable, but partial aggregation between particles is observed.

 Δ: The viscosity is slightly increased, but it can be used.

 ×: Viscosity was remarkable and unusable.

 XX: After emulsification, it solidified (gelled) within 2 to 3 days.

[Size effect test] 0.15% of the sizing composition for papermaking obtained above was added to a pulp slurry (BKP L / N = 8/2, Canadian Standard Freeness 360 ml) having a concentration of 0.24%, and a polyamide epichlorohydrin resin was used as a fixing agent. (Product name sponge
After adding 0.05% of 557H Dick Hercules Co., Ltd. and stirring for 1 minute, a wet paper having a basis weight of 60 g / m ² was obtained with a hand-making apparatus manufactured by Noble & Wood. In addition, papermaking pH
Was 7.0. The wet paper was pressed until the moisture content became 59.0%, and then dried with a drum dryer at 80 ° C. for 90 seconds. Immediately after drying, paper having a moisture content of 3.5% was obtained. Immediately, the degree of Stekigt sizing of the paper was measured in accordance with JISP-8122. The remaining pieces of paper were stored for 7 days in an atmosphere of 20 ° C. and a relative humidity of 65%, and the sizing degree after 7 days was measured. In addition, the addition rate of the above-mentioned chemicals is a solid content weight% with respect to dry pulp weight.

[Production Example of Modified Starch, Comparative Production Example] Production Example 1 Hydrogen peroxide-treated corn starch (water 12%)
114 parts) and stirred at 85 ° C. for 1 hour. next,
Reduce the temperature to 60 ° C or lower, 3.4 parts of 50% sodium hydroxide, 7
5% glycidyl trimethyl ammonium chloride 18.7
And stirred for 4.5 hours. Thereafter, the temperature is lowered to 30 ° C. or lower, and 121 parts of water and 1.8 parts of 98% sulfuric acid are added. The resulting modified starch solution had a cationic group substitution degree of 0.12 and a viscosity (25%).
C) was 12 centipoise with a 4% aqueous solution.

Production Example 2 A modified starch was produced in the same manner as in Production Example 1, except that the amount of 75% glycidyltrimethylammonium chloride was changed to 36 parts. The resulting modified starch solution had a cationic group substitution degree of 0.21 and a viscosity (25 ° C.) of 4%.
The aqueous solution was 13.5 centipoise.

Production Example 3 A modified starch was produced in the same manner as in Production Example 1 except that the amount of 75% glycidyltrimethylammonium chloride was changed to 58 parts. The obtained modified starch solution has a cationic group substitution degree of 0.29 and a viscosity (25 ° C.) of 4%.
The aqueous solution was 13.5 centipoise.

Production Example 4 111 parts of hypochlorous acid-treated potato starch (containing 10% of water) was added to 220 parts of water, and the mixture was stirred at 40 ° C. for 0.5 hour. Then, 50
14 parts of sodium hydroxide, raise the temperature to 65 ° C
Stir for hours. Further, 53 parts of 50% 3-chloro-2-hydroxypropyltrimethylammonium chloride is added, the temperature is raised to 70 ° C., and the mixture is stirred for 3 hours. Then the temperature
At 30 ° C. or lower, add 136 parts of water and 5.4 parts of 90% acetic acid. The resulting modified starch solution has a degree of substitution of the cationic group of 0.18,
The viscosity (25 ° C.) was 5 centipoise in a 4% aqueous solution.

Comparative Production Example 1 A modified starch was produced in the same manner as in Production Example 1, except that the amount of 75% glycidyltrimethylammonium chloride was changed to 8 parts. The obtained modified starch had a degree of cationic group substitution of 0.05 and a viscosity (25 ° C.) of 12.5 centipoise in a 4% aqueous solution.

Comparative Production Example 2 4.5 parts of 50% sodium hydroxide and 50 parts of sodium sulfate were dissolved in 125 parts of water, and corn starch (containing 10% water) was used.
Quickly put in one copy. Next, 5 parts of diethylaminoethyl chloride was added, and the mixture was stirred at 45 ° C for 5 hours.
Lower to 40 ° C and add 8 parts of propylene oxide.
Stir for hours. In addition, add 18 parts of 35% hydrogen peroxide water,
Stir for 4 hours. Thereafter, the pH is lowered to 4.5 by adding dilute hydrochloric acid, the reaction product is separated by filtration, washed with water and dried. The resulting modified starch has a degree of substitution of diethylaminoethyl group of 0.05 and a degree of substitution of hydroxypropyl group of 0.1.
0, viscosity (25 ° C.) was 10 centipoise with 8% aqueous solution.

Example 1 The amount of lignin sulfonic acid which is 30% by weight of the solid content based on ketene dimer, the processed starch solution prepared in Production Example 1 and the amount of lignin sulfonic acid which is 1% by weight of the solid content based on water and ketene dimer Sodium (hereinafter abbreviated as SLS) is mixed. The mixture is heated at about 90-95 ° C. for about 1 hour, cooled to 70 ° C. and then adjusted to pH 3.5 with 15% sulfuric acid.

Next, the raw material linear saturated fatty acid composition of the mixture was C14 = 2.2.
% C16 = 39.2% C18 = 58.6%, and after addition of ketene dimer (hereinafter referred to as ketene dimer A) produced using hydrogenated tallow as a starting material,
After emulsifying at a pressure of 2000 kg / cm ² using a high pressure discharge homogenizer, the mixture was diluted and cooled to obtain a sizing composition having a ketene dimer content of 15% and a solid content of about 20%.

The dispersion stability of this sizing composition was evaluated by the above-described test evaluation method. The results were ◎ at 5 ° C., ◎ at 20 ° C., and ◎ at 32 ° C. In addition, the results of the size effect test showed that the degree of Stighit sizing was 12 seconds immediately after papermaking and 30 seconds after seven days of papermaking.

Comparative Example 1 A sizing composition having a ketene dimer content of 15% and a solid content of about 20% was obtained in the same manner as in Example 1 except that the modified starch was produced in Comparative Production Example 1. The dispersion stability was poor at 5 ° C., × at 20 ° C., and XX at 32 ° C.

Example 2 and Comparative Example 2 The same procedure as in Example 1 was repeated except that the modified starch was replaced with the one manufactured in Production Example 2 (Example 2) and the one manufactured in Comparative Production Example 2 (Comparative Example 2). Ketene dimer min 15
% And a solid content of about 20%. The dispersion stability and size effect (Stekigt sizing degree) are as shown in Table 1 below.

Examples 3 to 7, Comparative Examples 3 to 5 Ketene dimer, modified starch, quantitative relationship other than changing the type of anionic dispersant as shown in Table-2, and all other conditions were the same as in Example 1. A sizing composition having a dimer content of 15% and a solid content of about 20% was obtained. Table 2 shows their dispersion stability and size effect (Stekigt sizing degree).

Comparing the same kind of ketene dimer from Table-2,
Example 6 shows better size effect and dispersion stability than Comparative Example 3. Similarly, Example 7 is superior to Comparative Example 4. Examples 3, 4, and 5 show better dispersion stability than Comparative Example 5.

〔The invention's effect〕

The papermaking sizing composition of the present invention has an excellent size effect,
In particular, there is an effect that the rising of the size is good and the dispersion stability is also excellent.

Continuation of the front page (56) References JP-A-60-258245 (JP, A) JP-A-60-139896 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21H 3 / 02

Claims (1)

(57) [Claims] 1. A ketene dimer compound represented by the following general formula: (Wherein R ₁ and R ₂ represent the same or different hydrocarbon groups having 8 to 30 carbon atoms) and (B) a modified starch having a substitution degree (DS) of a cationic group per anhydroglucose unit in the following range: And an aqueous dispersion containing 0.1 <DS ≦ 1.0 and (C) an anionic dispersant having a sulfonic acid group or a sulfate group.